Bronchiolitis Obliterans Research Articles

Infectious and Non-Infectious Pulmonary Complications in HCT Patients Treated with Post Transplant Cyclophosphamide (PTCy) Based Gvhd Prophylaxis

Introduction: Pulmonary complications are a leading cause of mortality and morbidity amongst pts undergoing hematopoietic stem cell transplantation (HCT). Increasingly, allogeneic HCT recipients are undergoing HCT with PTCy based GVHD prophylaxis. While lower rates of severe GVHD has been reported with PTCy, increased infection and organ toxicity has also been seen compared with standard calcineurin inhibitor (CNI) prophylaxis. The incidence and outcomes of pulmonary complications, both infectious and non-infectious/immune in pts receiving PTCy remain poorly characterized. Therefore, we aimed to assess for these in this study. Methods: We performed a retrospective review of pts between 2012-2022 who underwent 1st allogeneic BMT and received PTCy as part of GVHD prophylaxis. We identified pts requiring hospitalization for pulmonary complications. Infectious cases were categorized as bacterial, fungal, viral, or mixed. Bacterial pneumonia was defined as fever, cough, dyspnea, purulence sputum, and new or progressive radiographic evidence of infiltrate not explained by a non-infectious cause, treated with at least 5 days of antibiotics. Viral and fungal pneumonia were diagnosed based on identified organism. Noninfectious complications included idiopathic pulmonary syndrome (IPS), diffuse alveolar hemorrhage (DAH), cryptogenic organizing pneumonia (COP), and bronchiolitis obliterans syndrome (BOS). IPS was defined as radiographic evidence of alveolar infiltrates, dyspnea, cough, increased work of breathing or oxygen requirements, exclusion of infection or alternate pathology, and treated with high-dose systemic corticosteroids. DAH was defined as radiographic evidence of widespread alveolar injury, increased work of breathing or oxygen requirements, and persistent and progressive bloody return on BAL. COP was defined as pathologic evidence of organizing pneumonia on transbronchial lung biopsy in the absence of pathogens. BOS was defined as FEV1/FVC <0.7 and FEV1 <75% with a ≥10% decline over <2 years. Results: A total of 224 pts were identified. Median age at HCT was 55 years (20-78) (Table 1). 138 (64%) were male. The median comorbidity index (HCT-CI) score was 3 and median Karnofsky Performance Score was 80. 56%(n=125) pts underwent HCT with nonmyoablative conditioning, 78% (n=157) underwent HCT with a haploidentical donor, and 65% (n=145) of grafts were peripheral blood. 4%(n=10) were current smokers at time of HCT, 38% (n=84) were former smokers. 16% (n=35) had an existing diagnosis of asthma or COPD. 72 (32%) pts were hospitalized for pneumonia at any point after HCT. There were 23 bacterial pneumonias (30%), 20 viral (27%), 13 fungal (18%), and 12 were mixed (17%) (Table 2). There were 4 pts (6%)with documented pneumonia of unknown etiology due to rapid progression to death or hospice. 10 pts (4%) developed IPS with a median onset of 153 days (20-354). 2 pts (1%) developed COP with a mean onset of 754 days (388 - 1119). 5 pts (2%) developed BOS with a median onset of 336 days (153-677). 8 pts (4%) developed DAH with a median onset of 48 days (20-152). Among all patients, 57 pts (25%) required mechanical ventilation at any point post-HCT, and 18 pts (8%) were prescribed home oxygen at any point post-HCT. Overall, 80pts (77%) died due to non-relapse causes. 29 deaths (28%) were pulmonary related, (21 (20%) infectious and 8 (8%) noninfectious). Of the noninfectious pulmonary deaths, 3 pts died due to IPS, and 5 died due to DAH. Conclusion: In our cohort of pts receiving PTCy based GVHD prophylaxis, significant infectious pulmonary complications were common and were fatal in 9.4% of pts. Infections were the major driver of pulmonary related mortality, however, we observed noninfectious/immunologic pulmonary complications at a rate within or only slightly below the previously reported ranges among transplanted pts predominantly receiving CNI based prophylaxis.

UBA1 Mutations Identify a Rare but Distinct Subtype of Myelodysplastic Syndromes

Background Mutations in UBA1 are associated with VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome, an adult-onset inflammatory disorder (Beck DB et al. NEJM 2020). Approximately 40% of VEXAS patients are also diagnosed with myelodysplastic syndromes (MDS). We previously profiled UBA1 p.M41 mutations in a select subset of the International Working Group for MDS (IWG-PM) cohort (Bernard E et al. NEJM Evid 2022) including 375 male patients lacking disease-defining mutations or established disease classification by WHO guidelines, and identified 28 patients (7%) with UBA1 p.M41T/V/L mutations (Cohort A, Sirenko M et al. Blood 2022). However, the prevalence and characteristics of UBA1 mutations in MDS have not been systematically evaluated in a representative MDS population. Methods We used targeted next-generation sequencing of the full UBA1 locus to profile 2027 diagnostic and treatment-naive MDS samples (Cohort B, 61% male) ascertained through the IWG-PM (Figure 1). Clinical associations of UBA1 mutations were evaluated and clinical history was reviewed for inflammatory conditions when available. Results In Cohort B, 35 UBA1 mutations in 34 (1.7%) patients were identified, of which 20 (0.97%) had likely pathogenic variants and 14 had variants of unknown significance (VUS). Likely pathogenic variants included 13 p.M41T/V/L mutation (variant allele fraction [VAF] range 0.013-0.94), and 7 non-p.M41 mutations where 6/7 had VAF>0.35: 2 with p.S56F (VAF 0.87 and 0.93), 2 p.A478S (VAF 0.72 and 0.80), 2 p.S621C (VAF 0.80 and 0.82) and 1 p.Y55H (VAF 0.025). Three VUS were in female patients. 204 cases were profiled by both assays and of those, all 8 ddPCR positive cases were identified by NGS with concordant VAF (R2=0.999 p<0.0001). Integration of Cohort A and B (n=2,198) yielded 40 patients (all male, median age 72; range 44-89 years) with pathogenic UBA1 variants. The WHO 2016 classification (available for n=38 of 40) was MDS-SLD/MLD (25), MDS-EB1 (4), MDS-U (3), CMML (2), MDS-RS-MLD (1), aCML (1), MDS/MPN-RS-T (1), MDS/MPN-U (1). Patients had a median of 1 myeloid gene mutation in addition to UBA1 (range: 0-4) with most frequent co-occurring events in TET2 (n=12), DNMT3A (n = 10), ASXL1 (n=3), SF3B1 (n=3) and loss of the Y chromosome (n=5). In 8 patients with pathogenic UBA1 > 2% VAF and co-occurring DNMT3A mutations, DNMT3A and UBA1 VAF were correlated (slope = 0.88, r = 0.87, p = 0.0005), suggesting that co-mutation may lead to clonal expansion. Conversely, TET2 co-mutations were either subclonal (n=4) or clonal (n=8) to UBA1. Among patients with pathogenic UBA1 variants, the majority had IPSS-M Very-Low/Low risk (73% 27/37). In contrast, patients with VUS were more likely to have Moderate or High risk (64% 7/11). Partial clinical history was available for 33 cases with pathogenic UBA1 variants. 50% (9/18) had inflammatory-rheumatic disease (IRD) including psoriatic arthritis, relapsing polychondritis, Sweet syndrome, bronchiolitis obliterans with organizing pneumonia, ear chondritis, and rosacea. 3 patients had more than one IRD. 8 were treated for IRD with steroids (n=6) or methotrexate (n=2). 4 patients had MGUS. Other manifestations included vacuoles (4/8), thromboembolic disease (5/16), non-infection fever (5/14), weight loss (4/14), ocular symptoms (5/15), arthralgia (3/16), chondritis (5/15), and other inflammation (6/14). IRD diagnosis usually preceded MDS (average time 0.28 years; range 16.5 years prior to 1.4 years after). Three patients transformed to acute myeloid leukemia (AML). One patient had a low VAF UBA1 p.M41V (0.0002 by ddPCR) and TET2, SF3B1, FLT3, and ASXL2 co-mutations at baseline. The second had UBA1 p.S56F (VAF 0.868) and a Chr 7q deletion. The third had VUS UBA1 p.R869L (VAF 0.222) and IRF1, NFE2 and RRAS co-mutations. Among the other UBA1-mutant patients that died or were censored after 1 year (n=37), none transformed to AML. Conclusion Within the large, representative, diagnostic and well-characterized IWG-PM MDS cohort, we find likely pathogenic UBA1 mutations in 1% of patients, with enrichment in male patients with few or no mutations in myeloid driver genes (7%). UBA1-mutant patients were predominantly IPSS-M low risk with a median of 1 additional mutation, usually in DNMT3A or TET2. UBA1 mutations may define a distinct subset of MDS and its recognition in future guidelines will improve the management of patients with MDS/VEXAS overlap.

Mitochondrial Pyruvate Carrier Inhibition Mitigates Murine Chronic Graft Versus Host Disease By Attenuating the Germinal Center Reaction

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potent therapy for many hematopoietic diseases and malignancies. However, the long-term efficacy of allo-HSCT is limited by the development of chronic graft versus host disease (cGVHD). During cGVHD, interactions between donor-derived T follicular helper cells (TFH) and germinal center B cells (GCB) result in the production of alloreactive class-switched affinity-matured antibodies that attack host tissues, causing multi-organ damage and tissue fibrosis. Novel treatment approaches are warranted to treat cGVHD since it is often refractory to current broad immune suppressive drugs. In this study we sought to delineate the metabolic dependencies of germinal center (GC) immune cells to discover new strategies to treat active murine cGVHD. We utilized a multi-organ mouse model of cGVHD that includes bronchiolitis obliterans (BO), a severe cGVHD manifestation seen in the clinic. Toward that end, B10.BR (H2 k) recipients received myeloablative conditioning with cyclophosphamide and total body irradiation before receiving MHC mismatched C57BL/6 (H2 b) donor T cell depleted bone marrow with (cGVHD) or without (BM only control) a low dose of splenic T cells. First, we sought to assess the metabolic dependencies of TFH during cGVHD progression through Seahorse metabolic flux assays. TFH sorted early (D28) from cGVHD mice were highly glycolytic with an increased extracellular acidification rate (ECAR) and less reliant on oxidative phosphorylation (OXPHOS) as reflected by a decreased oxygen consumption rate (OCR). However, TFH sorted later (D49) from cGVHD mice demonstrated a dramatic shift in their metabolic profile to a decreased ECAR and an increased OCR indicating a transition from glycolysis towards OXPHOS as disease progresses. To understand which substrates are driving increased OXPHOS and to identify promising metabolic targets, we performed unbiased metabolomics of sort purified TFH from BM only and cGVHD mice on D49 post-transplantation (Fig A). Among the top fifty differential metabolites, cGVHD TFH had a decreased abundance of anaplerotic amino acids (serine, glutamine) and an increased abundance of multiple breakdown products of anaplerotic amino acids (tryptophan, leucine), indicative of increased replenishment of tricarboxylic acid (TCA) cycle intermediates. Notably these metabolomics data showed a decreased abundance of glutamine which is consistent with an increase in glutaminolysis, validating our prior findings that TFH cells that cause cGVHD/BO depend on glutaminolysis ( Johnson MO, Cell 2018). Additionally, there was an increased abundance of pyruvate, which can be transported into mitochondria to fuel the TCA cycle through the mitochondrial pyruvate carrier (MPC). Based on these findings we chose to target the MPC since it has a central role in tying pyruvate to the TCA cycle and OXPHOS. We assessed the effect of an MPC inhibitor (7ACC1) on the GC reaction utilizing an ex vivo co-culture assay of TFH and B cells. 7ACC1 added to this co-culture system resulted in a significant reduction in the production of class-switched immunoglobulin compared to vehicle treatment. To assess the in vivo efficacy, we administered 7ACC1 daily through intraperitoneal injections after establishment of cGVHD (Days 28-49) in the cGVHD/BO mouse model. 7ACC1 treatment resulted in a significant reduction of the GC reaction with significantly decreased TFH and GCB frequencies. Additionally, there was a significant improvement in cGVHD disease severity as evidenced by assessing pulmonary function tests in anesthetized, intubated and mechanically ventilated mice using plethysmography. In contrast to the high resistance and low compliance seen in cGVHD/BO mice, 7ACC1 treated recipients had significantly improved lung function, comparable to the BM only controls (Fig B). In summary, inhibiting MPC mediated transport of pyruvate represents a novel approach to stifling the metabolic demands of TFH as their energy dependency shifts from glycolysis towards OXPHOS during the course of cGVHD/BO disease progression.

Clinical risk factors and prognostic model for patients with bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation.

Bronchiolitis obliterans syndrome (BOS) is a common and potentially devastating noninfectious pulmonary complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Currently, predictive tools for BOS are not available. We aimed to identify the clinical risk factors and establish a prognostic model for BOS in patients who undergo allo-HSCT. We retrospectively identified a cohort comprising 195 BOS patients from 6100 consecutive patients who were allografted between 2008 and 2022. The entire cohort was divided into a derivation cohort and a validation cohort based on the time of transplantation. Via multivariable Cox regression methods, declining forced expiratory volume at 1 s (FEV1) to <40%, pneumonia, cGVHD except lung, and respiratory failure were found to be independent risk factors for the 3-year mortality of BOS. A risk score called FACT was constructed based on the regression coefficients. The FACT model had an AUC of 0.863 (95% CI: 0.797-0.928) in internal validation and 0.749 (95% CI: 0.621-0.876) in external validation. The calibration curves showed good agreement between the FACT-predicted probabilities and actual observations. The FACT risk score will help to identify patients at high risk and facilitate future research on developing novel, effective interventions to personalize treatment.

Transcriptome analysis reveals the impact of NETs activation on airway epithelial cell EMT and inflammation in bronchiolitis obliterans

Bronchiolitis obliterans (BO) is a chronic airway disease that was often indicated by the pathological presentation of narrowed and irreversible airways. However, the molecular mechanisms of BO pathogenesis remain unknown. Although neutrophil extracellular traps (NETs) can contribute to inflammatory disorders, their involvement in BO is unclear. This study aims to identify potential signaling pathways in BO by exploring the correlations between NETs and BO. GSE52761 and GSE137169 datasets were downloaded from gene expression omnibus (GEO) database. A series of bioinformatics analyses such as differential expression analysis, gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG), and gene set enrichment analysis (GSEA) were performed on GSE52761 and GSE137169 datasets to identify BO potential signaling pathways. Two different types of BO mouse models were constructed to verify NETs involvements in BO. Additional experiments and bioinformatics analysis using human small airway epithelial cells (SAECs) were also performed to further elucidate differential genes enrichment with their respective signaling pathways in BO. Our study identified 115 differentially expressed genes (DEGs) that were found up-regulated in BO. Pathway enrichment analysis revealed that these genes were primarily involved in inflammatory signaling processes. Besides, we found that neutrophil extracellular traps (NETs) were formed and activated during BO. Our western blot analysis on lung tissue from BO mice further confirmed NETs activation in BO, where neutrophil elastase (NE) and myeloperoxidase (MPO) expression were found significantly elevated. Transcriptomic and bioinformatics analysis of NETs treated-SAECs also revealed that NETs-DEGs were primarily associated through inflammatory and epithelial-to-mesenchymal transition (EMT) -related pathways. Our study provides novel clues towards the understanding of BO pathogenesis, in which NETs contribute to BO pathogenesis through the activation of inflammatory and EMT associated pathways. The completion of our study will provide the basis for potential novel therapeutic targets in BO treatment.

Clonal GZMK +CD8 + t Cells Are Identified As a Hallmark of Pathogenesis of Cgvhd-Induced Bronchiolitis Obliterans Syndrome after Allogeneic Hematopoietic Stem Cell Transplantation

Chronic graft-versus-host disease (cGVHD), as the main cause of non-relapse mortality (NRM), remains the major complication leading to reduced patient-reported quality of life (QoL) and increased incidence of secondary malignancies in long-term transplant recipients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Bronchiolitis obliterans syndrome (BOS) is a late-stage complication of cGVHD involving the lungs and one of its most devastating outcomes. BOS currently has no satisfactory therapeutic approaches partly due to the limited understanding of pathogenic mechanisms. To generate a comprehensive immune atlas of patients with cGVHD, we have enrolled 22 patients with cGVHD and 11 patients without cGVHD following allo-HSCT and collected their peripheral blood mononuclear cell (PBMC) samples, respectively. According to the organs involved in cGVHD, 10 patients had cGVHD with only skin involvement (abbreviated as cGVHD-skin here), 12 patients had lung involvement with diagnosed cGVHD-BOS. By applying mass cytometry, bulk RNA-sequencing and cytokine array, we revealed that circulating Granzyme K (GZMK)-expressing CD8 + T cells were accumulated in cGVHD-BOS patients. As lung fibrosis is one of the hallmarks of cGVHD-BOS, we next explore whether it is related to the increase of our identified GZMK + CD8 + T cells. We performed in vitro culture of human embryonic lung fibroblast HFL-1 cells in the presence or absence of 100ng/ml human GZMK. Supporting our hypothesis, GZMK dramatically boosted the expression levels of fibrosis-related genes including collagen type I alpha 1 chain (COL1A1), fibronectin (FN1), detected by both RT-qPCR and western blotting, suggesting an important role of GZMK in the pathogenesis of cGVHD-BOS. In order to validate the role of GZMK +CD8 + T cells in cGVHD-BOS, we established murine cGVHD-BOS model after allo-HSCT. We next performed 10×genomics single-cell RNA sequencing (scRNA-seq) and paired single-cell TCR sequencing analysis of engrafted living donor mouse immune cells (FVS510 - H2 b+ H2 k- CD45 +), which were isolated from lung tissues of cGVHD-BOS mice (n=3) and of control mice (n=3), respectively. We identified three T cell clusters that highly expressed Gzmk as well as CCR5, namely CD8 EX Gzmk, CD8 EM CCL4 and CD8 EFF Gzma. Total Gzmk +CD8 + T cells were significantly enriched in lungs of cGVHD-BOS mice compared with those of control mice ( p &amp;lt; 0.01), in which CD8 EX Gzmk and CD8 EM CCL4 cells were significantly dominant in lung tissues of cGVHD-BOS mice. We further explored the unique transcriptional states of Gzmk + CD8 + T cells in lungs of cGVHD-BOS mice. Compared with Gzmk - CD8 + T cells in cGVHD-BOS lungs, GO pathway enrichment analysis showed that Gzmk + CD8 + T cells are highly cytotoxic subtypes with migratory features. Notably, Gzmk + CD8 + T cell subsets, CD8-EX-Gzmk and CD8-EM-CCL4, also exhibited significantly higher numbers of TCR clonotypes in BOS lungs compared to controls, which confirmed that GZMK +CD8 + T cells infiltrated and expanded in lungs of cGVHD-BOS mice. Furthermore, we observed that three Gzmk + CD8 + T cell subsets had highly overlapping TCR repertoires, indicating that similar immunodominant epitopes may drive the clonal expansion of Gzmk + CD8 + T cells. Finally, to further explore novel promising drugs to treat cGVHD-BOS by inhibition of the expression of GZMK in T cells, we screened 40 small molecular drugs, which were selected from a library containing 932 drugs targeting epigenetic regulators, to treat T cells for 48h. We revealed that Bosutinib, the second-generation BCR-ABL1-targeting tyrosine kinase inhibitor (TKI), could inhibit GZMK expression on CD8 + T cells in vitro. More importantly, the reduced lung resistance with restored lung compliance were observed in cGVHD-BOS mice treated with Bosutinib, suggesting that Bosutinib had effect on reducing of lung stiffness and pulmonary fibrosis. Multiple immunofluorescence staining confirmed that Bosutinib treatment could reduce the infiltration of Gzmk +CD8 +T cells and collagen deposition in lungs of cGVHD-BOS mice. Our data shed light on the new therapeutic approaches for cGVHD-BOS.

ACC1 Inhibition Enhances Treg Gvhd Treatment Efficacy through Regulation of Mitochondrial Fusion and Elongation

Regulatory T-cells (Treg) play a critical role in preventing autoimmune and alloimmune reactions. Clinical trials demonstrated that Treg adoptive transfer significantly reduced but did not uniformly eliminate grades II-IV graft-vs-host disease (GVHD). Treg more dominantly rely on fatty acid oxidation (FAO) as a fuel source, in contrast to glycolytic conventional T-cells. We hypothesized that increasing FAO would augment Treg efficacy by increasing potency and persistence, thereby ultimately decreasing the Treg cell number required to enhance Treg-mediated GVHD reduction. The FAO and fatty acid synthesis (FAS) pathways compete for acetyl-CoA use. Acetyl-CoA carboxylase-1 (ACC1) skews acetyl-CoA toward FAS and results in downstream inhibition of CPT1a, the rate-limiting enzyme in FAO. ACC1 deletion or inhibition skews naive CD4 T-cell toward FAO, favoring Treg over Th17 differentiation. To precisely determine the role of ACC1 on in vivo Treg-mediated suppression of GVHD, we tested the effects of a 2-hour treatment of murineTreg with ND630, a pharmacological inhibitor of ACC1 currently in clinical trials for hepatic steatosis, or Treg-specific ACC1 knockout (KO). ACC1 inhibition or KO increased in vitro Treg suppressive function, and when infused into mice with established bronchiolitis obliterans (BOS) and chronic GVHD (cGVHD), ACC1KO Treg were more potent than wild-type Treg in reversing BOS pulmonary resistance (FigA), a finding consistent in each of 3 replicate transplants. Mechanistically, both ND630 treated Treg and ACC1KO Treg demonstrated an increased oxygen consumption rate (OCR), a surrogate for mitochondrial oxidative phosphorylation (OXPHOS), a critical source of ATP for Treg. This was associated with an increase in uptake of BoDipyC16, a synthetic fatty acid, suggesting exogenous fatty acids may drive the increase in OXPHOS through FAO. IACS, an OXPHOS inhibitor, abrogated OCR augmentation and precluded increased suppressive function after ND630 treatment, indicating a critical role for OXPHOS in driving Treg suppressor function. To directly evaluate effects on Treg mitochondria, where OXPHOS occurs, Treg were stained with MitoTracker dyes that measure mitochondrial mass and membrane potential, two key surrogate measurements for mitochondrial function. Compared to controls, ND630 treated and ACC1KO Treg each showed increased mitochondrial mass and membrane potential, as well as enhanced mitochondrial polarization (membrane potential to mass ratio), which is required for full Treg functionality. Expansion and scanning electron microscopic analysis of Treg mitochondria revealed enhanced mitochondrial fusion and elongation after ND630 treatment ( FigB). This mitochondrial structural change boosts OXPHOS, consistent with a direct effect of ACC1 inhibition/KO on mitochondrial fitness. In light of these mitochondrial morphology changes, we hypothesized that directly modifying the mitochondria itself, without inhibiting ACC1, might result in augmented Treg function. Consistent with this hypothesis, a 2-hour treatment with the combination of M1 (mitochondrial fusion promoter) and mDIVI1 (mitochondrial fission inhibitor), significantly enhanced Treg function in vitro, and enhanced Treg OCR to a similar degree as ND630. Electron microscopy confirmed that M1/mDIVI1 treatment resulted in a similar degree of mitochondrial fusion as ND630 treatment. Similar to ACC1KO Treg, M1/mDIVI1 treated Treg were more potent than control Treg in reversing established cGVHD. To further explore mitochondrial fusion effects on Treg function, we used siRNA to knockdown the critical mitochondrial fusion protein mitofusin 1 (MFN1). A 50% decrease in MFN1 protein significantly decreased Treg in vitro functionality and OCR, and treatment of MFN1 knockdown Treg with ND630 had no functional or metabolic effect (FigC), pointing to mitochondrial fusion as a critical component of the mechanism for ACC1 inhibition/KO. In summary, ACC1 inhibition or deletion amplifies murine Treg potency resulting in superior metabolic fitness, and greater efficacy in treating cGVHD mice with established BOS, in part through enhancing mitochondrial fusion. Since ND630 is already under investigation in patients, ACC1 inhibition with ND630 could be readily translatable for clinical trials with a goal of utilizing Tregs with inhibited or deleted ACC1 to improve GVHD therapy.

Budesonide Added to Post-Transplantation Cyclophosphamide, Tacrolimus and Mycophenolate Mofetil for Prevention of Graft-Versus-Host Disease

Background: Topically active corticosteroids have been shown to effectively treat inflammatory bowel disease with a systemic steroid-sparing effect. However, previous studies have not demonstrated their efficacy in preventing graft-versus-host disease (GVHD) when combined with the standard GVHD prophylaxis regimen consisting of calcineurin inhibitors and methotrexate. We hypothesized that the addition of orally administered ileal-controlled-release budesonide to the post-transplant cyclophosphamide (PTCy)-based regimen could effectively prevent severe acute gastrointestinal GVHD. In this study, we present outcomes of the first 43 consecutively treated patients (pts) with the PTCy-tacrolimus (T), mycophenolate mofetil (M) and budesonide (B) (PTCy-TMB) as a GVHD prophylaxis regimen after allogeneic stem cell transplantation (alloSCT). Methods: Pts with hematologic malignancies received their first alloSCT at our institution between 05/2020-04/2023. Thirty one pts received conditioning with fludarabine (160 mg/m 2) + melphalan (100-140 mg/m 2) + TBI (2-4Gy) or thiotepa 5 mg/kg. Twelve pts received fludarabine (150mg/m 2) + cyclophosphamide (29mg/kg) and TBI 4Gy ± ATG (4.5 mg/kg). GVHD prophylaxis consisted of Cy (50 mg/kg on D+3 and +4), T (trough goal 6-10 ng/mL), M (15mg/kg TID) and budesonide (3 mg TID) starting on D+5 and continued until D+90 followed by a weekly taper if no acute GVHD (aGVHD) occurred. T was continued for at least 6 months followed by a taper, unless otherwise indicated. Results: The median age was 50 years (range 22-73), 39 pts had hematologic malignancies including AML (N=14), ALL (N=11) and NHL (N=8). Seven pts (16%) classified as high/very-high DRI. The median of HCT-CI was 4 (range 0-7). Donors were haploidentical (N=32), MSD (N=8), MUD (N=1), MMSD (1) and MMUD (N=1). PBSCs were used in 28 pts (65%). Thirty pts (70%) received RIC regimens. Median follow-up was 407 days (range 91-996 days). At day 100, the cumulative incidence (CI) of grade 2 aGVHD was 7.0% (95%CI 1.8-17.2), while none developed grade 3-4 aGVHD (Figure 1). One patient had severe chronic GVHD (bronchiolitis obliterans) with CI at 2 years of 3.2% (95%CI 0-14.0). The CI of any systemic steroid use at D+100 and D+180 was 30.2% (95%CI 17.4-44.1) and 44.8% (95%CI 28.9-59.5), respectively. Among the pts who received treatment for aGVHD, the median cumulative systemic steroid exposure (in prednisone equivalents) was 1,318 mg (IQR 623-3,775) at D+100 and 1,325 mg (IQR 525-1,640) at D+180, with a median treatment duration of 40 days (IQR 25-110). At 1 year, the OS, PFS, GRFS, relapse and NRM were 79.6% (95%CI 61.4-89.9), 69.8% (95%CI 51.6-82.3), 66.6% (95%CI 48.4-79.8), 15.3% (95%CI 6.2-28.2) and 14.9% (95%CI 5.3-29.1), respectively. The 1-year CI of newly diagnosed/worsening hyperglycemia and Cushing syndrome was 18.2% (95%CI 7.9-31.9) and 5.0% (95%CI 0.9-14.2), respectively. 3 pts (7%) required insulin treatment. The median absolute lymphocyte count (ALC) at day 30, 90 and 180 was 200/mcL, 300/mcL and 500/mcL, respectively, with no differences in the median ALC at D+180 among pts with and without GVHD. Median cell numbers of CD3 +, CD3 +/CD4 +, CD3 +/CD8 +, CD19 + and CD56 + at 1, 3, 6 months post-transplant were D+30 - 63/mcL, 18/mcL, 34/mcL, 1/mcL, 87/mcL, D+90 - 111/mcL, 64/mcL, 34/mcL, 9/mcL, 216/mcL and D+180 - 269/mcL , 78/mcL , 126/mcL , 7/mcL, 189/mcL, respectively. After 10/2022 pts were tested routinely for Reg3α and ST2 (baseline and retested if developed any signs/symptoms of aGVHD). Among 18 tested pts at baseline, the median number (range) of Reg3α and ST2 at baseline was 28 ng/mL (16-90) and 23,308 pg/mL (4,678-56,226), respectively. Three low-risk pts developed grade 1 aGVHD (N=2) and grade 2 aGVHD (N=1). Fourteen pts with GI sign/symptoms after transplant showed median number (range) of Reg3α and ST2 of 78 ng/mL (16-837) and 34,904 pg/mL (13,329-160,000), respectively. Only one pt with high-risk aGVHD algorithm developed grade 2 aGVHD (Figure 1). Conclusions: The addition of budesonide to PTCy-based GVHD prophylaxis regimen (PTCy-TMB) is feasible and appears to be effective in preventing severe GI aGVHD, without compromising transplant outcomes and immunologic reconstitution.

ALVR106, an Off-the-Shelf, Multivirus-Specific T-Cell Therapy, for the Treatment of Respiratory Viral Infections: Results from a Phase 1, First-in-Human, Dose-Ranging Trial

Background: Community-acquired respiratory viruses such as influenza (Flu), human metapneumovirus (hMPV), parainfluenza virus (PIV), and respiratory syncytial virus (RSV) are leading causes of morbidity and mortality after hematopoietic cell transplant (HCT) or solid organ transplant (SOT). While these viruses may begin in the upper respiratory tract, ~50% of cases progress to the lower respiratory tract, potentially leading to more severe conditions such as pneumonia, bronchiolitis, bronchiolitis obliterans, and chronic lung allograft dysfunction. ALVR106 is an allogeneic, off-the-shelf, polyclonal, multi-respiratory virus T-cell therapy specific for Flu, hMPV, PIV, and RSV. ALVR106 is generated by exposing peripheral blood mononuclear cells to peptide mixtures followed by ex vivo expansion in presence of activating cytokines. The expanded T cells are Th1-polarized, polyfunctional, and selectively able to kill viral target cells. ALVR106 cells have not shown alloreactivity, attesting to their selectivity and safety for use in HCT or SOT. Methods: In this first-in-human, placebo (PBO)-controlled, dose-ranging trial, HCT or SOT recipients 17 years or older with upper or mild lower respiratory tract infections (URTI/LRTI) caused by Flu, hMPV, PIV, or RSV were randomized in a 3:1 ratio to receive ALVR106 or PBO. Four doses of ALVR106 ranging from 1 × 10 5 cells/kg to 2 × 10 6 cells/kg were planned to be given to 4 cohorts of 4 patients each. Patients receive up to 2 infusions of ALVR106 or PBO once every 14 days and will be followed for up to 1 year. The primary objective was safety as measured by treatment emergent adverse events (AEs), AEs of special interest (acute and chronic graft vs host disease (GvHD), cytokine release syndrome (CRS), infusion related reactions (IRR), and progressive dyspnea), and clinical laboratory abnormalities from baseline (BL) through 12 weeks after the last infusion. Secondary endpoints included evaluation of antiviral activity by qualitative PCR assay by nasal swab and a composite endpoint through D28 which included change from BL in Radiation Therapy Oncology Group Lung Toxicity Scale Grade and viral detection from nasal swab. Patients with an improvement in symptoms or undetectable virus were considered partial responders (PR); those with improved symptoms and undetectable virus were complete responders (CR), and those whose condition did not improve or worsen from BL were non-responders (NR). To assess functional T-cell immune reconstitution and frequency of circulating virus-specific T cells, IFN-g virus-specific ELISpot analysis was performed on serial blood samples over time. ELISpot results will be presented. Preliminary study results presented herein will be unblinded at the time of data presentation. Results: 16 patients were dosed: four in Cohorts (C) 1 and 2, five in C3, and three in C4. Table shows BL demographics, disease characteristics, and blinded results for safety and antiviral activity by composite endpoint. Cohorts 2, 3, and 4 had at least 1 patient with mild LRTI at BL, no patients in C1 had LRTI. All patients received at least 1 infusion. No patients with Flu were enrolled. In these blinded results, no differences were seen in rate or severity of AEs among cohorts. Four patients (25%) had AEs possibly related to treatment (ALVR106 or PBO); all were Grade 1 (mild) in severity. These related events were reported in 1 patient each: diarrhea, ear pressure, neutrophil count decrease, and 1 patient had pyrexia, cGvHD oral, and aGvHD skin. Eight patients (50%) had serious AEs (SAEs), none related to treatment. One patient (6%) in C3 had G2 progressive dyspnea not related to treatment. One patient (6%) in C1 had Grade I aGVHD skin and cGVHD oral; both were considered possibly related to treatment (ALVR106 or PBO). No patients had Grade II-IV aGVHD, cGVHD, IRR, or CRS. No clinically significant changes from BL or trends over time in lab abnormalities or vital signs were seen. At Day 28, all patients in C1 and C2 had undetectable respiratory virus via nasal swab, except 1 patient in C1 who missed D28 visit due to COVID-19; 4/5 (80%) in C3 were undetectable; and 2/3 (67%) in C4 were undetectable. Conclusion: In this ongoing trial-the first-in-human, double-blind, PBO-controlled trial of virus-specific T cell therapy in transplant recipients with respiratory infection-ALVR106 was safe and well tolerated, supporting its continued evaluation in HCT and SOT recipients.

Inhibition of Bromodomain and Extraterminal Domain (BET) Proteins Alleviates Chronic Graft- Versus-Host-Disease Via Modulating the CXCR5/CXCL13 Axis

Introduction: Chronic graft-versus-host disease (cGVHD) is a severe complication of allogeneic hematopoietic cell transplant (allo-HCT) often leading to transplant-mediated mortality. Studies have shown that T follicular helper cells (Tfh) upregulate CXCR5 and migrate into the lymphoid organ follicles in response to CXCL13 promoting germinal center (GC) B cell proliferation and differentiation of plasma cells resulting in pathogenic antibody production and profibrotic pathways associated with cGVHD. In contrast, T follicular regulatory cells (Tfr) modulate the magnitude of the GC response; thus, the balance of Tfr/Tfh could be crucial to mitigating cGVHD.Bromodomain and extra-terminal domain (BET) proteins are epigenetic readers influencing transcription of a multitude of inflammatory genes and our lab has previously reported pharmacological inhibition of BET, through OPN-51107, improves survivability and limits disease progression in murine models of acute GVHD that led to opening the first-in-human clinical trial of OPN-51107 in steroid refractory acute GVHD. We demonstrated BET proteins to be important in modulating acute GVHD pathogenesis, however, mechanisms of BET regulation within cGVHD are largely unknown. Here, using OPN-51107 we aim to further investigate mechanisms of cGVHD pathogenesis and identify successful BET inhibition-based therapeutic approaches. Methods: We used a Bronchiolitis Obliterans model (B6-&amp;gt;B10.br) of cGVHD. Mice were administered 120mg/kg cyclophosphamide (D-3 and D-2) and 8Gy irradiation (D-1) as a conditioning regimen followed by B6 T-cell depleted bone marrow cells with and without CD45.1 B6 splenocytes. Mice that did not receive allogeneic splenocytes served as controls and did not develop GVHD. Recipients of allogeneic splenocytes were treated with a BET inhibitor - OPN-51107 at 10mg/kg 3x/weekly, or vehicle, from D28-54(+ 4) via oral gavage. Resting lung elastance and resistance was measured using the Flexivent system. At the time of lung function analysis, lung and liver tissue was harvested and stained via Hesson's Trichrome to identify and quantify collagen deposition. We performed immunofluorescence to quantify alveolar alloantibody deposition. Spleen and lung cells were stimulated with PMA/I and analyzed via spectral flow cytometry. An inflammatory murine cytokine array (#ARY006, R&amp;D Systems) was used to analyze circulating plasma cytokine levels. Results: BET inhibition via OPN-51107 treatment decreased lung resistance (vehicle vs OPN-51107 =1.16Rrs vs 0.83Rrs p&amp;lt;0.05) and elastance (vehicle vs. OPN-51107=62Ers vs. 45Ers p&amp;lt;0.05). OPN-51107 treatment also significantly reduced alveolar antibody (Ig) deposition per area compared to vehicle (vehicle vs. OPN-51107= 4.91% vs. 3.3% p=0.01) and collagen deposition (vehicle vs. OPN-51107=19.0% vs. 12.9% p&amp;lt;0.05) and liver (vehicle vs. OPN-51107=19.3% vs. 2.35% p&amp;lt;0.0001). Congruently, BET inhibition decreased B220-CD19- CD138+mature plasma cells (vehicle vs. OPN-51107=15% vs 9.1% p&amp;lt;0.05) in the lung. Serum cytokine array analysis revealed a significant decrease in circulating CXCL13, relevant to Tfh migration as well as a decrease in other proinflammatory cytokines - CXCL9, MCP-1, IL3, RANTES and G-CSF important for macrophage activation and pathogenicity in OPN-51107 compared to vehicle treated mice. BET inhibition reduced splenic Tfh while increasing Tfr, thereby increasing Tfr:Tfh ratio (vehicle vs. OPN-51107= 5% vs. 9% p&amp;lt;0.05). Furthermore, total splenic CD19+ B-cells (vehicle vs. OPN51107= 70% vs. 33% p&amp;lt;0.001) as well as CXCR5 expression on B-cells were decreased in OPN-51107 treated mice (MFI vehicle vs. OPN-51107= 4744 vs. 571.5 p&amp;lt;0.0001). Conclusion: OPN-51107 improved lung function which correlated with significantly decreased lung fibrosis and antibody deposition in a BO model of cGVHD. BET inhibition reduces cGVHD immune pathology through decreased inflammatory cytokine production, promotion of GC Tfr cell population and modulates B-cell proliferation and/or trafficking. Significance: Using OPN-51107 in a BO model of cGVHD we demonstrate that BET inhibition is a feasible therapeutic strategy to reduce disease severity and improve lung function.

A Novel Protocol Improves Engraftment in Tαβ + Cell Depleted Haplo-HSCT for Patients with Thalassemia Major

Background: Hematopoietic stem cell transplantation (HSCT) remains a proven curative approach for patients with thalassemia major (TM) over long-term practice. However, achieving successful engraftment and managing graft-versus-host disease (GVHD) continue to pose significant challenges. While low incidence of GVHD has been observed in Tαβ + cell-depleted HSCT (TDH) from haploidentical donors, graft failure (GF) remains a considerable concern, particularly in patients with TM. To enhance the engraftment in TM-TDH, we conducted this prospective/retrospective single-center clinical study. Method: A total of 137 patients diagnosed with TM received TDH at the BMT-center, Taixin Hospital, between March 2021 and April 2023. The median age of the patients was 7 years (ranging from 2 to 19 years), with 89 males and 48 females. The median follow-up time was 408 days (ranging from 99 to 857 days). The conditioning regimen consisted of Thymoglobulin on -day 21, followed by 3-Gy total body irradiation on -day 11. On -day 10, the patients received an infusion of donor lymphocytes (2*10 8/kg), followed by cyclophosphamide (Cy) at a dose of 50mg/kg on days -8, -7, and -2, and 25mg/kg on day -1. Additionally, blood-concentration adjusted busulfan was administered on days -6 to -4, fludarabine at a dose of 40mg/kg on days -6 to -2, and thiotepa at 10mg/kg on day -3. For GVHD prophylaxis, short-term (&amp;lt; 6 months) low-dose tacrolimus or sirolimus with or without mycophenolate mofetil was used. The mean infused CD34+ cells were 31.09 (ranging from 14.25 to 61.12) *10 6/kg, TCRγδ+ cells were 39.49 (ranging from 5.18 to 140.39) *10 6/kg, and NK cells were 109.18 (ranging from 27.52 to 309.41) *10 6/kg, respectively. The targeted infusion of TCRαβ+ cells was aimed at 1.5-2.0*10 5/kg. Results: Out of the 137 patients, 133 achieved successful engraftment (97.1%) with median engraftment times of 16 days (ranging from 9 to 48 days) for ANC to reach 0.5x10 9/L, 11 days (ranging from 1 to 23 days) for HB to reach 80g/L, and 10 days (ranging from 5 to 22 days) for platelets to reach 20x10 9/L, respectively. GF was observed in four patients. Among them, two patients with GF underwent salvage alternative donor second HSCT on +day 19 and +day 32, respectively, and are currently thalassemia-free. One patient received infusion of cryopreserved auto-peripheral blood stem cell and continues to live with TM. Unfortunately, four patients passed away, with one GF patient dying from suspected virus myocarditis on +day 11, one potentially due to virus hepatitis or hepatic GVHD on day +188, and the remaining two from virus bronchiolitis obliterans on +day 211 and +day 254, respectively. The overall survival (OS) and thalassemia-free survival (TFS) rates were 96.5% and 94.3%, respectively. The incidence of GF and transplant-related mortality (TRM) were 2.9% and 3.5%, respectively (Fig.). Acute GVHD of grade I-II and grade III-IV was observed in 10.53% and 9.02% of patients, respectively, while mild and moderate chronic GVHD occurred in 7(5.1%) and 1(0.7%) patient(s), respectively. The incidence of veno-occlusive disease was mild and limited. C onc lusion: The current study demonstrates the efficacy of a novel protocol in enhancing engraftment in TDH for patients with TM and with low incidence of both acute GvHD and chronic GvHD. This approach represents a significant advancement in the field of TM-TDH. Fig.1 Curve of OS, TFS, TRM and Rejection in TM-TDH

Current Status and Trends in Lung Transplant Research Funded by the National Natural Science Foundation of China.

This study aimed to analyze research projects on lung transplant funded by the National Natural Science Foundation of China from 1986 to 2022 and to provide a scientific reference for lung transplant research. We identified research hotspots and frontiers in the field of lung transplant research using CiteSpace visualization. From 1986 to 2022, the National Natural Science Foundation of China funded 93 projects related to lung transplant, with an average of 2.51 projects and ¥0.94 million annually. The National Natural Science Foundation of China funded 30 institutions across 20 provinces, with general and youth science foundation projects comprising 45.16% and 41.93% of the total projects, respectively. The main categories of disciplines included H0113 respiratory intervention, tracheal reconstruction, and lung transplantation; H1105 organ transplantation and transplant immunization; and H0109 acute lung injury and acute respiratory distress syndrome. The research hotspots mainly included ischemia-reperfusion injury, gene regulation, obliterative bronchiolitis, rejection reaction, T cells, and stem cells. The 6 main research clusters were ischemia-reperfusion injury, immune tolerance, obliterative bronchiolitis, stem cells, pulmonary fibrosis, and rejection reaction. The main key word bursts in the past 5 years were "vein endothelial" and "ex vivo lung perfusion." In the past 37 years, National Natural Science Foundation of China-funded projects have significantly advanced the clinical application and basic research of lung transplantation. However, compared with developed countries and other solidorgan transplantations, several problems still require attention and improvements in lung transplant research in China.

Effects of respiratory flora regulation on microbial environment and IL-10/STAT3 signaling pathway in the bronchiolitis obliterans after lung transplantation.

Our purpose of this study was to explore the application effect of respiratory flora regulation in bronchiolitis obliterans after lung transplantation, and its regulatory effect on the microbial environment of the lesion and the IL-10/STAT3 signaling pathway. 25 clean-grade C57BL/6 male mice and 5 BALB/c male mice were selected for orthotopic tracheal transplantation and postoperative respiratory flora regulation in a hospital animal room from Jan 2019 to Dec 2021. Next, the changes in the microbial environment and the IL-10/STAT3 signaling pathway before and after respiratory flora regulation were compared, so as to evaluate the regulatory effect of this method. The Simpson index did not show a significant difference before and after respiratory flora regulation intervention (P>0.05). However, the Chao1, ACE, Shannon, and Actinobacteria dominant indices were higher after the intervention. There were significant changes in the abundance of Proteobacteria, Bacteroidetes, Acidobacteria, Firmicutes, Propionibacterium, Corynebacterium, Staphylococcus, and Streptococcus after the intervention (P<0.05). Additionally, IL-10 and STAT3 levels were higher after the intervention and showed significant differences (P<0.05) compared to before. Regulating the respiratory tract flora can improve the microbial environment of bronchiolitis obliterans post-lung transplantation. This helps balance the respiratory flora, increase IL-10 and STAT3 levels, and aid in the recovery of inflammatory responses.

Sirolimus Long-Term Tolerability and Impact on Kidney Function in Lung Transplantation: A Single-Center Experience

After lung transplant, 2 common complications are calcineurin inhibitor (CNI) induced nephrotoxicity and bronchiolitis obliterans syndrome. The objective of this study was to investigate the long-term effects of sirolimus conversion after lung transplantation. This was a retrospective cohort study of patients who had undergone lung transplantation at a single center from June 2003 to December 2016. We compared patients converted to a sirolimus-based regimen to those maintained on our standard tacrolimus-based regimen. Kidney function, pulmonary function, and immunosuppression concentrations were compared between the groups. Additionally, indications, toxicity monitoring parameters, and discontinuation rates for sirolimus were collected. During the study period, 176 of the 205 patients who underwent lung transplants were converted to a sirolimus-containing regimen (86%). The most common reason for sirolimus initiation was impairment of kidney function or CNI-associated neurotoxicity. Sirolimus was initiated at a median of 150 days post-transplantation and continued for a medium time of 5.02 (2.27-7.85) years. Of those patients converted to sirolimus, 39 (22%) had sirolimus subsequently discontinued secondary to an adverse event. No difference in pulmonary function was found between the groups at 1- and 3-years post-transplantation. In the sirolimus group, the median estimated glomerular filtration rate improved by 8.6 mL/min/1.73 m2 at 3 months post-conversion (P < .001), which was maintained at both 1 and 3 years (P=.014 and .025, respectively). Sirolimus is a viable immunosuppressant option after lung transplant, which successfully allows for the reduction or withdrawal of the CNI, resulting in sustained improvement in kidney function.

Trichosanthin-derived peptide Tk-PQ attenuates immune rejection in mouse tracheal allotransplant model by suppressing PI3K-Akt and inducing type II immune polarization

Obliterative bronchiolitis (OB) is one of the main complications affecting long-term survival of post-lung transplantation patients. In this study, we evaluated the efficacy of Tk-PQ (a peptide derived from trichosanthin) in alleviating OB in a mouse ectopic tracheal transplant model. We found that post-transplantation treatment of Tk-PQ significant ameliorated OB symptoms including luminal occlusion, epithelial cells loss and fibrosis in the allograft. In addition, Tk-PQ promoted immune suppressive environment by inducing Th2 polarization and increasing Treg population which in turn led to elevated levels of anti-inflammatory cytokines IL-4, IL-10, IL-33 and decreased levels of pro-inflammatory IL-1β. Mechanistically, we used transcriptome analysis of splenic T cells from allografted mice to show that Tk-PQ treatment down-regulated the PI3K-Akt signaling pathway. Indeed, the immune suppression phenotypes of Tk-PQ was recapitulated by a PI3K inhibitor LY294002. Taken together, Tk-PQ regulates post-transplantation immuno-rejection by modulating the balance of T cell response via the PI3K-Akt pathway, making it a promising peptide based immune rejection suppressant for patients receiving allotransplant.

Risk factors and clinical characteristics of acute and chronic cutaneous graft-versus-host disease in pediatric patients undergoing hematopoietic stem cell transplantation.

Acute and chronic cutaneous graft-versus-host disease (GVHD) are common complications following hematopoietic stem cell transplantation (HSCT) in pediatric patients. In this retrospective study, we explored the risk factors and clinical characteristics of acute and chronic cutaneous GVHD in a case series of children undergoing HSCT at a tertiary referral hospital. We found that 36% of acute cutaneous GVHD was severe and these patients were more likely to have an unrelated donor, and that children with acute cutaneous GVHD who progressed to chronic cutaneous GVHD had a higher proportion of malignant diseases, total body irradiation, and bronchiolitis obliterans compared to those who did not progress to chronic cutaneous GVHD. Our study highlights the importance of identifying and monitoring these high-risk patients to improve the clinical management and outcomes of cutaneous GVHD in pediatric HSCT recipients.

Chronic Lung Allograft Dysfunction Is Associated with Significant Disability after Lung Transplantation-A Burden of Disease Analysis in 1025 Cases.

Chronic lung allograft dysfunction (CLAD) is the leading cause of death after the first postoperative years of lung transplantation (LTx). To assess the number of disability-adjusted life years (DALYs) per patient with severe CLAD. The clinical and demographic data of patients who received their lung transplantation between 2010 and 2020 in the Hanover Medical School (Germany) were evaluated. A total of 1025 lung transplant patients were followed for a median of 51 months (4.25 years); the median age at transplantation was 52.8 (interquartile range (IQR) 19) years. More than a quarter of transplant patients (271/1025 or 26.4%) developed CLAD, mostly (60%) of the bronchiolitis obliterans syndrome (BOS) phenotype. Of the CLAD patients, 99, or 36.5%, suffered from significant disability, which on average occurred after 2 years (IQR 2.55). The survival of CLAD patients with disability after transplantation was significantly lower compared to that of patients without CLAD (median 4.04 versus 5.41 years). Adjusted to the DALY estimation approach, CLAD patients lost 1.29 life years (YLL) and lived for 0.8 years with their disability (YLD), adding up to 2.09 DALYs (range 1.99-2.72) per patient. CLAD after lung transplantation is a major public health problem and is associated with substantial disability and costs. Further work is needed to develop therapeutic interventions that reduce its development.

Early chest CT abnormalities to predict the subsequent occurrence of chronic lung allograft dysfunction

IntroductionChronic lung allograft dysfunction (CLAD) can take two forms: bronchiolitis obliterans syndrome (BOS) or restrictive allograft syndrome (RAS). The aim was to determine if chest-CT abnormalities after lung transplantation (LTx) could predict CLAD before respiratory functional deterioration.Materials and methodsThis monocentric retrospective study analyzed consecutive patients who underwent LTx from January 2015 to December 2018. Initial CT post-LTx (CTi) and a follow-up CT at least 9 months post-LTx (CTf) were reviewed. CLAD was defined as a persistent respiratory functional decline (> 20% of basal FEV1) outside acute episode. A Cox regression was performed in univariate, then in multivariate analysis (including features with p < 0.01 in univariate or of clinical importance) to determine risk factors for CLAD. Subgroup analyses were made for BOS, RAS, and death.ResultsAmong 118 LTx patients (median (min–max) 47 (18–68) years), 25 developed CLAD during follow-up (19 BOS). The median time to CLAD since LTx was 570 days [150–1770]. Moderate pulmonary artery stenosis (30–50%) was associated with the occurrence of CLAD on CTi (hazard ratio HR = 4.6, CI [1.6–13.2]) and consolidations and pleural effusion on CTf (HR = 2.6, CI [1.3–4.9] and HR = 4.5, CI [1.5–13.6] respectively). The presence of mosaic attenuation (HR = 4.1, CI [1.4–12.5]), consolidations (HR = 2.6, CI [1.3–5.4]), and pleural effusions (p = 0.01, HR = 5.7, CI [1.4–22.3]) were risk factors for BOS on CTf. The consolidations (p = 0.029) and pleural effusions (p = 0.001) were risk factors for death on CTf.ConclusionsCTi and CTf in the monitoring of LTx patients could predict CLAD. Moderate pulmonary artery stenosis, mosaic pattern, parenchyma condensations, and pleural effusions were risk factors for CLAD.Critical relevance statementThere is a potential predictive role of chest CT in the follow-up of LTx patients for chronic lung allograft dysfunction (CLAD). Early chest CT should focus on pulmonary artery stenosis (risk factor for CLAD in this study). During the follow-up (at least 9 months post-LTx), parenchymal consolidations and pleural effusions were shown to be risk factors for CLAD, and death in subgroup analyses.Key points• Pulmonary artery stenosis (30–50%) on initial chest-CT following lung transplantation predicts CLAD HR = 4.5; CI [1.6–13.2].• Pleural effusion and consolidations 1 year after lung transplantation predict CLAD and death.• Early evaluation of lung transplanted patients should evaluate pulmonary artery anastomosis.Graphical

Impact of lung transplantation on diastolic dysfunction in recipients with pretransplant pulmonary hypertension

ObjectivePulmonary hypertension can cause left ventricular diastolic dysfunction through ventricular interdependence. Moreover, diastolic dysfunction has been linked to adverse outcomes after lung transplant. The impact of lung transplant on diastolic dysfunction in recipients with pretransplant pulmonary hypertension is not defined. In this cohort, we aimed to assess the prevalence of diastolic dysfunction, the change in diastolic dysfunction after lung transplant, and the impact of diastolic dysfunction on lung transplant outcomes. MethodsIn a large, single-center database from January 2011 to September 2021, single or bilateral lung transplant recipients with pulmonary hypertension (mean pulmonary artery pressure > 20 mm Hg) were retrospectively identified. Those without a pre- or post-transplant echocardiogram within 1 year were excluded. Diastolic dysfunction was diagnosed and graded according to the American Society of Echocardiography 2016 guideline on assessment of diastolic dysfunction (present, absent, indeterminate). McNemar's test was used to examine association between diastolic dysfunction pre- and post-transplant. Kaplan–Meier and Cox regression analysis were used to assess associations between pre–lung transplant diastolic dysfunction and post–lung transplant 1-year outcomes, including mortality, major adverse cardiac events, and bronchiolitis obliterans syndrome grade 1 or higher–free survival. ResultsOf 476 primary lung transplant recipients, 205 with pulmonary hypertension formed the study cohort (mean age, 56.6 ± 11.9 years, men 61.5%, mean pulmonary artery pressure 30.5 ± 9.8 mm Hg, left ventricular ejection fraction < 55% 9 [4.3%]). Pretransplant, diastolic dysfunction was present in 93 patients (45.4%) (grade I = 8, II = 84, III = 1), absent in 16 patients (7.8%), and indeterminate in 89 patients (43.4%), and 7 patients (3.4%) had missing data. Post-transplant, diastolic dysfunction was present in 7 patients (3.4%) (grade I = 2, II = 5, III = 0), absent in 164 patients (80.0%), and indeterminate in 15 patients (7.3%), and 19 patients (9.3%) had missing data. For those with diastolic dysfunction grades in both time periods (n = 180), there was a significant decrease in diastolic dysfunction post-transplant (148/169 patients with resolved diastolic dysfunction; McNemar's test P < .001). Pretransplant diastolic dysfunction was not associated with major adverse cardiac events (hazard ratio [HR], 1.08, 95% CI, 0.72-1.62; P = .71), bronchiolitis obliterans syndrome–free survival (HR, 0.67, 95% CI, 0.39-1.56; P = .15), or mortality (HR, 0.70, 95% CI, 0.33-1.46; P = .34) at 1 year. ConclusionsDiastolic dysfunction is highly prevalent in lung transplant candidates with normal left ventricular systolic function and pulmonary hypertension, and resolves in most patients after lung transplant regardless of patient characteristics. Pre–lung transplant diastolic dysfunction was not associated with adverse lung or cardiac outcomes after lung transplant. Collectively, these findings suggest that the presence of diastolic dysfunction in lung transplant recipients with pulmonary hypertension has no prognostic significance, and as such diastolic dysfunction and the associated clinical syndrome of heart failure with preserved ejection fraction should not be considered a relative contraindication to lung transplant in such patients.

Evaluation of safety and efficacy of allogeneic adipose tissue-derived mesenchymal stem cells in pediatric bronchiolitis obliterans syndrome (BoS) after allogeneic hematopoietic stem cell transplantation (allo-HSCT)

BackgroundAllo-HSCT is a definite approach for the management of a wide variety of lethal and debilitating malignant and non-malignant disorders. However, its two main complications, acute and chronic graft-versus-host disease (GVHD), exert significant morbidities and mortalities. BoS, as a manifestation of chronic lung GVHD, is a gruesome complication of allo-HSCT, and for those with steroid-refractory disease, no approved second-line therapies exist. Mesenchymal stem cells (MSCs) exert anti-inflammatory and growth-promoting effects, and their administration against a wide range of inflammatory and neurologic disorders, as well as GVHD, has been associated with promising outcomes. However, literature on the safety and effectiveness of MSC therapy for BoS and pediatric cGVHD is scarce.MethodsWe designed a single-arm trial to administer adipose tissue (AT)-derived MSCs to pediatric patients with refractory BoS after allo-HSCT. AT-MSCs from obese, otherwise healthy donors were cultured in an ISO class 1 clean room and injected into the antecubital vein of eligible patients with a dose of 1 × 106/kg. The primary endpoints included a complete or partial response to therapy [in terms of increased forced expiratory volume in one second (FEV1) values and steroid dose reduction] and its safety profile.ResultsFour eligible patients with a median age of 6.5 years were enrolled in the study. Steroid-induced osteoporosis and myopathy were present in three cases. A partial response was evident in three cases after a single injection of AT-MSCs. The treatment was safe and tolerable, and no treatment-related adverse events were noted. Two patients developed manageable COVID-19 infections one and 4 months after AT-MSC injection. After a median follow-up duration of 19 months, all cases are still alive and have had no indications for lung transplantation.ConclusionsAT-MSCs could be safely administered to our pediatric cases with BoS post-allo-HSCT. Considering their advanced stage of disease, their sub-optimal functional capacity due to steroid-induced complications, and COVID-19 infection post-treatment, we believe that AT-MSC therapy can have possible efficacy in the management of pediatric BoS. The conduction of further studies with larger sample sizes and more frequent injections is prudent for further optimization of AT-MSC therapy against BoS.Trial registration Iranian Registry of Clinical Trials (IRCT), IRCT20201202049568N2. Registered 22 February 2021, https://en.irct.ir/trial/53143.