Lung Allograft Rejection Research Articles

Resolution of Acute Lung Allograft Rejection Detected by Probe-based Confocal Laser Endomicroscopy.

Resolution of Acute Lung Allograft Rejection Detected by Probe-based Confocal Laser Endomicroscopy.

Successful prevention of BK-polyomavirus nephropathy using extracorporeal photopheresis for immunosuppression minimisation following severe BK polyomavirus replication after kidney transplantation in a double lung transplant recipient, a case report

BackgroundBK-polyomavirus (BKpyV) nephropathy (BKVN) is associated with end-stage kidney disease in kidney and non-kidney solid organ transplantation, with no curative treatment.Case presentationA 45-year-old woman with a past medical history of double lung transplantation subsequently developed end-stage kidney disease, of undetermined origin. One month after receiving a kidney transplant, a diagnosis of early BKVN was suspected, and in retrospect was a reasonable cause for the loss of her native kidneys. Minimisation of immunosuppression, achieved through extracorporeal photopheresis, allowed clearance of BKpyV and so prevented nephropathy. Both lung and kidney grafts had a satisfactory and stable function after one year of follow-up, with no rejection.ConclusionsExtracorporeal photopheresis may have facilitated minimisation of immunosuppression and BKpyV clearance without lung allograft rejection.

QuantiFERON CMV Test and CMV Serostatus in Lung Transplant: Stratification Risk for Infection, Chronic and Acute Allograft Rejection.

The QuantiFERON CMV (QCMV) test evaluates specific adaptive immune system activity against CMV by measuring IFN-γ released by activated CD8+ T lymphocytes. We aimed to evaluate the QCMV test as a predictive tool for CMV manifestations and acute or chronic lung allograft rejection (AR and CLAD) in lung transplant (LTx) patients. A total of 73 patients were divided into four groups based on donor and recipient (D/R) serology for CMV and QCMV assay: group A low-risk for CMV infection and disease (D-/R-); group B and C at intermediate-risk (R+), group B with non-reactive QCMV and group C with reactive QCMV; group D at high-risk (D+/R-). Group D patients experienced higher viral replication; no differences were observed among R+ patients of groups B and C. D+/R- patients had a higher number of AR events and group C presented a lower incidence of AR. Prevalence of CLAD at 24 months was higher in group B with a higher risk of CLAD development (OR 6.33). The QCMV test allows us to identify R+ non-reactive QCMV population as the most exposed to onset of CLAD. This population had a higher, although non-significant, susceptibility to AR compared to the R+ population with reactive QCMV.

IL-10 Is Critical for Regulation of Cytotoxic CD4+NKG7+ T Cells in Lung Allograft Rejection but Is Not Required for Allograft Acceptance.

Lung transplant remains the primary therapeutic option for patients with end-stage lung disease, but long-term survival rates remain suboptimal compared with other solid organ transplants. Acute cellular rejection (ACR) is a significant challenge in lung transplant recipients, with T cell-mediated mechanisms playing a major role. IL-10 is known for its immunoregulatory function, although its specific role in lung allograft rejection remains unclear. Using the mouse orthotopic lung transplant model, we investigated the role of IL-10 in regulating alloeffector T cell responses. Unexpectedly, we found that IL-10 was not required for early costimulation blockade-induced allograft acceptance. However, IL-10 deficiency or blockade resulted in increased CD4+ T cell numbers, proliferation, graft infiltration, and alloeffector responses. In the absence of IL-10, CD4+ T cell responses predominated over CD8 responses during ACR in contrast to wild-type mice. Type 1 immunity (IFN-γ) responses along with elevated CD4+NKG7+ and CD4+CD107a+ responses predominated during ACR, highlighting a critical regulatory role for IL-10 in modulating CD4+ T cell alloimmune responses. We further demonstrated increased colocalization of NKG7 and CD107a in CD4+ T cells from IL-10-deficient allografts, suggesting coordination in cytotoxic activity. Together, our findings highlight a critical role for IL-10 in regulation of cytotoxic CD4+NKG7+ T cells, an effector population that needs further investigation to elucidate their role in lung allograft rejection.

Hepatitis C viremic lung transplantation to aviremic recipients: Comprehensive outcomes and post-transplant viremia.

Direct-acting antiviral (DAA) therapy has revolutionized solid organ transplantation by providing an opportunity to utilize organs from HCV-viremic donors. Though transplantation of HCV-viremic donor organs into aviremic recipients is safe in the short term, midterm data on survival and post-transplant complications is lacking. We provide a midterm assessment of complications of lung transplantation (LT) up to 2 years post-transplant, including patient and graft survival between HCV-viremic transplantation (D+) and HCV-aviremic transplantation (D-). This is a retrospective cohort study including 500 patients from 2018 to 2022 who underwent LT at our quaternary care institution. Outcomes of patients receiving D+ grafts were compared to those receiving D- grafts. Recipients of HCV antibody+ but PCR- grafts were treated as D- recipients. We identified 470 D- and 30 D+ patients meeting inclusion criteria. Crude mortality did not differ between groups (p=.43). Patient survival at years 1 and 2 did not differ between D+ and D- patients (p=.89, p=.87, respectively), and graft survival at years 1 and 2 did not differ between the two groups (p=.90, p=.88, respectively). No extrahepatic manifestations or fibrosing cholestatic hepatitis (FCH) occurred among D+ recipients. D+ and D- patients had similar rates of post-transplant chronic lung allograft rejection (CLAD) (p=6.7%vs. 12.8%, p=.3), acute cellular rejection (60.0%vs. 58.0%, p=.8) and antibody-mediated rejection (16.7%vs. 14.2%, p=.7). There is no difference in midterm patient or graft survival between D+ and D-LT. No extrahepatic manifestations of HCV occurred. No differences in any type of rejection including CLAD were observed, though follow-up for CLAD was limited. These results provide additional support for the use of HCV-viremic organs in selected recipients in LT.

Disulfiram, an Anti-alcoholic Drug, Targets Macrophages and Attenuates Acute Rejection in Rat Lung Allografts.

Macrophages contribute to post-transplant lung rejection. Disulfiram (DSF), an anti-alcoholic drug, has an anti-inflammatory effect and regulates macrophage chemotactic activity. Here, we investigated DSF efficacy in suppressing acute rejection post-lung transplantation. Male Lewis rats (280-300g) received orthotopic left lung transplants from Fisher 344 rats (minor histocompatibility antigen-mismatched transplantation). DSF (0.75mg/h) monotherapy or co-solvent only (50% hydroxypropyl-β-cyclodextrin) as control was subcutaneously administered for 7 days (n = 10/group). No post-transplant immunosuppressant was administered. Grades of acute rejection, infiltration of immune cells positive for CD68, CD3, or CD79a, and gene expression of monocyte chemoattractant protein and pro-inflammatory cytokines in the grafts were assessed 7 days post-transplantation. The DSF-treated group had significantly milder lymphocytic bronchiolitis than the control group. The infiltration levels of CD68+ or CD3+ cells to the peribronchial area were significantly lower in the DSF than in the control groups. The normalized expression of chemokine ligand 2 and interleukin-6 mRNA in allografts was lower in the DSF than in the control groups. Validation assay revealed interleukin-6 expression to be significantly lower in the DSF than in the control groups. DSF can alleviate acute rejection post-lung transplantation by reducing macrophage accumulation around peripheral bronchi and suppressing pro-inflammatory cytokine expression.

(86) - Divergent Transcriptional Features of Obstructive and Restrictive Forms of Chronic Lung Allograft Rejection Modeled in a Single Mouse Strain Combination

(86) - Divergent Transcriptional Features of Obstructive and Restrictive Forms of Chronic Lung Allograft Rejection Modeled in a Single Mouse Strain Combination

Coordinated elimination of bacterial taxa optimally attenuates alloimmunity and prolongs allograft survival

This study aimed to dissect the relationship between specific gut commensal bacterial subgroups, their functional metabolic pathways, and their impact on skin allograft outcome and alloimmunity. We previously showed that oral broad-spectrum antibiotic (Abx) pretreatment in mice delayed skin, heart, and lung allograft rejection and dampened alloimmune responses. Here, rationally designed Abx combinations targeting major bacterial groups were used to elucidate their individual contribution to modulating alloimmune responses. Abx cocktails targeting intestinal gram-negative, gram-positive, or anaerobic/gram-positive bacteria by oral gavage, all delayed skin allograft rejection, and reduced alloreactive T cell priming to different extents. Notably, the most pronounced extension of skin allograft survival and attenuation of alloimmunity were achieved when all gut bacterial groups were simultaneously targeted. These results suggest a model in which the strength of the alloimmune response is additively tuned up by gut microbial diversity. Shotgun metagenomic sequencing enabled strain-level resolution and identified a shared commensal, Parabacteroides distasonis, as the most enriched following all Abx treatments. Oral administration of P.distasonis to mice harboring a diverse microbiota significantly prolonged skin allograft survival, identifying a probiotic with therapeutic benefit in transplantation.

Donor IL-17 receptor A regulates LPS-potentiated acute and chronic murine lung allograft rejection.

Chronic lung allograft dysfunction (CLAD) is a major complication after lung transplantation that results from a complex interplay of innate inflammatory and alloimmune factors, culminating in parenchymal and/or obliterative airway fibrosis. Excessive IL-17A signaling and chronic inflammation have been recognized as key factors in these pathological processes. Herein, we developed a model of repeated airway inflammation in mouse minor alloantigen-mismatched single-lung transplantation. Repeated intratracheal LPS instillations augmented pulmonary IL-17A expression. LPS also increased acute rejection, airway epithelial damage, and obliterative airway fibrosis, similar to human explanted lung allografts with antecedent episodes of airway infection. We then investigated the role of donor and recipient IL-17 receptor A (IL-17RA) in this context. Donor IL-17RA deficiency significantly attenuated acute rejection and CLAD features, whereas recipient IL-17RA deficiency only slightly reduced airway obliteration in LPS allografts. IL-17RA immunofluorescence positive staining was greater in human CLAD lungs compared with control human lung specimens, with localization to fibroblasts and myofibroblasts, which was also seen in mouse LPS allografts. Taken together, repeated airway inflammation after lung transplantation caused local airway epithelial damage, with persistent elevation of IL-17A and IL-17RA expression and particular involvement of IL-17RA on donor structural cells in development of fibrosis.

Differentiation between lung allograft rejection and infection using donor-derived cell-free DNA and pathogen detection by metagenomic next-generation sequencing

BackgroundIn lung transplant recipients (LTRs), the primary causes of mortality are rejection and infection, which often present similar symptoms, making differentiation challenging. This study aimed to explore the diagnostic efficacy of plasma donor-derived cell-free DNA (dd-cfDNA) in conjunction with metagenomic next-generation sequencing (mNGS) for pathogen detection in differentiation between lung allograft rejection and infection in LTRs experiencing new-onset pulmonary complications. MethodsWe conducted a retrospective study on 188 LTRs who underwent lung or heart-lung transplantation at our institution from 2015 to 2021. The LTRs were categorized into three groups: stable, rejection, and infection. We measured plasma dd-cfDNA levels and utilized both mNGS and culture methods to identify pathogens in the bronchoalveolar lavage fluid (BALF). ResultsThe rejection group exhibited the highest levels of plasma dd-cfDNA (median 1.34 %, interquartile range [IQR] 1.06–2.19 %) compared to the infection group (median 0.72 %, IQR 0.62–1.07 %) and the stable group (median 0.69 %, IQR 0.58–0.78 %) (both p < 0.001). Within the infection group, a significantly higher level of dd-cfDNA was observed in the cytomegalovirus infection subgroup (p < 0.001), but not in the fungal (p > 0.05) or bacterial infection subgroups (p > 0.05), when compared to the stable group. Elevated dd-cfDNA levels, in combination with negative mNGS results, strongly indicated lung allograft rejection, with a positive predictive value and negative predictive value of 88.7 % and 99.2 %, respectively. ConclusionsPlasma dd-cfDNA in combination with BALF pathogen detection by mNGS shows satisfactory accuracy in differentiating lung allograft rejection from infectious complications.

Lung Transplant Recipients and COVID-19: Report of Two Cases.

Although the WHO has declared the end of the pandemic emergency, COVID-19 still poses a threat to immunocompromised patients. The COVID-19 pandemic has spread throughout the world over the last two years, causing a significant number of deaths. After three years, SARS-CoV-2 has lost its initial lethality but has shown a significantly worse prognosis for immunocompromised patients, especially those who have undergone lung transplantation, compared with the general population. This paper presents two compelling case studies that highlight the complex challenges of COVID-19 infection in lung transplant recipients. The first case involves a patient who received a bilateral lung transplant for pulmonary artery hypertension in 2009, followed by a kidney transplant in 2022. Surprisingly, despite an initially favorable clinical course after contracting COVID-19, the patient deteriorated rapidly and died within a few days due to extensive lung involvement. This case highlights the unpredictable nature of COVID-19 and its potentially devastating impact on lung transplant recipients. The second case involves a patient who underwent bilateral lung transplantation five years earlier for chronic obstructive pulmonary disease (COPD). This individual also contracted COVID-19 and had pre-existing complications, including chronic lung allograft rejection (CLAD) and diffuse bronchial stenosis. Following viral infection, the patient's clinical condition deteriorated rapidly, with worsening bronchial stenosis. This case highlights the ability of COVID-19 to exacerbate pre-existing pulmonary complications in transplant recipients. These cases highlight the urgent need for increased vigilance and tailored management strategies when dealing with COVID-19 in lung transplant recipients. The unpredictable and detrimental course of the disease observed in these patients highlights the importance of implementing stringent preventive measures, such as vaccination and strict adherence to infection control protocols, in this vulnerable population. Further research is essential to gain a full understanding of the unique dynamics of COVID-19 in lung transplant recipients and to develop targeted interventions to improve their outcomes.

A Breath of Fresh Air - Lung Transplantation Has Come of Age

A boundless spectrum of chronic lung diseases is said to effect over 500 million persons globally. Lung transplantation is a well-established therapeutic option for patients suffering from end-stage lung diseases, however waitlist mortality and primary graft failure remain major determinants as post-transplantation 5-year survival is just above 50 percent. Recent innovations in lung transplantation have been aimed at increasing organ availability, improving allograft quality, function, and longevity. Ex-vivo Lung Perfusion (EVLP) is an exciting modality responsible for multiple paths of lung allograft reconditioning as well as significantly extending preservation times. Mechanical circulatory support (MCS), specifically extracorporeal membrane oxygenation (ECMO) has consistently gained popularity not only for its use as a bridge to transplantation, but also its intraoperative role. In tandem, EVLP and ECMO have shown promising results in increasing the number of lung transplantations performed, therefore decreasing waitlist mortality. Primary graft dysfunction (PGD) and chronic lung allograft rejection (CLAD) continue to be the most feared predictors of poor outcomes. In this review we will highlight the historical progression of lung transplantation, its encumbrance, and the most recent advancements in promising techniques for long-term allograft protection and patient survival.

(100) Phosphorylated S6 Ribosomal Protein as an Additional Marker of Antibody-Mediated Rejection in Lung Allografts: A Multicentre Study

(100) Phosphorylated S6 Ribosomal Protein as an Additional Marker of Antibody-Mediated Rejection in Lung Allografts: A Multicentre Study

Downregulation of a tumor suppressor gene LKB1 in lung transplantation as a biomarker for chronic murine lung allograft rejection.

We recently demonstrated decreased tumor suppressor gene liver kinase B1 (LKB1) level in lung transplant recipients diagnosed with bronchiolitis obliterans syndrome. STE20-related adaptor alpha (STRADα) functions as a pseudokinase that binds and regulates LKB1 activity. A murine model of chronic lung allograft rejection in which a single lung from a B6D2F1 mouse was orthotopically transplanted into a DBA/2J mouse was employed. We examined the effect of LKB1 knockdown using CRISPR-CAS9 in vitro culture system. Significant downregulation of LKB1 and STRADα expression was found in donor lung compared to recipient lung. STRADα knockdown significantly inhibited LKB1, pAMPK expression but induced phosphorylated mammalian target of rapamycin (mTOR), fibronectin, and Collagen-I, expression in BEAS-2B cells. LKB1 overexpression decreased fibronectin, Collagen-I, and phosphorylated mTOR expression in A549 cells. We demonstrated that downregulation of LKB1-STRADα pathway accompanied with increased fibrosis, results in development of chronic rejection following murine lung transplantation.

(1273) Anti-Alcohol Drug to Target Macrophages Attenuates Acute Rejection in Rat Lung Allografts

(1273) Anti-Alcohol Drug to Target Macrophages Attenuates Acute Rejection in Rat Lung Allografts

(238) Downregulation of LKB1-Stradα Pathway in Circulating Exosomes as a Biomarker for Chronic Murine Lung Allograft Rejection

(238) Downregulation of LKB1-Stradα Pathway in Circulating Exosomes as a Biomarker for Chronic Murine Lung Allograft Rejection

The mitigating effect of exogenous carbon monoxide on chronic allograft rejection and fibrosis post-lung transplantation.

Small airway inflammation and fibrosis or bronchiolitis obliterans (BO) is the predominant presentation of chronic lung allograft dysfunction (CLAD) post-lung transplantation. Carbon monoxide (CO) is a critical endogenous signaling transducer with known anti-inflammatory and anti-fibrotic effects but its therapeutic potential in CLAD remains to be fully elucidated. Here we investigate the effect of inhaled CO in modulating chronic lung allograft rejection pathology in a murine orthotopic lung transplant model of BO (B6D2F1/J→DBA/2J). Additionally, the effects of CO on the activated phenotype of mesenchymal cells isolated from human lung transplant recipients with CLAD were studied. Murine lung allografts treated with CO (250 ppm×30 minutes twice daily from days 7 to 40 post-transplantation) demonstrated decreased immune cell infiltration, fibrosis, and airway obliteration by flow cytometry, trichrome staining, and morphometric analysis, respectively. Decreased total collagen, with levels comparable to isografts, was noted in CO-treated allografts by quantitative hydroxyproline assay. In vitro, CO (250 ppm×16h) was effective in reversing the fibrotic phenotype of human CLAD mesenchymal cells with decreased collagen I and β-catenin expression as well as an inhibitory effect on ERK1/2 MAPK, and mTORC1/2 signaling. Sildenafil, a phosphodiesterase 5 inhibitor, partially mimicked the effects of CO on CLAD mesenchymal cells and was partially effective in decreasing collagen deposition in murine allografts, suggesting the contribution of cGMP-dependent and -independent mechanisms in mediating the effect of CO. These results suggest a potential role for CO in alleviating allograft fibrosis and mitigating chronic rejection pathology post-lung transplant.

Donor Batf3 inhibits murine lung allograft rejection and airway fibrosis

Chronic lung allograft dysfunction (CLAD) limits survival after lung transplantation. Noxious stimuli entering the airways foster CLAD development. Classical dendritic cells (cDCs) link innate and adaptive immunity and exhibit regional and functional specialization in the lung. The transcription factor basic leucine zipper ATF-like 3 (BATF3) is absolutely required for the development of type 1 cDCs (cDC1s), which reside in the airway epithelium and have variable responses depending on the context. We studied the role of BATF3 in a mouse minor alloantigen-mismatched orthotopic lung transplant model of CLAD with and without airway inflammation triggered by repeated administration of intratracheal lipopolysaccharide (LPS). We found that cDC1s accumulated in allografts compared with isografts and that donor cDC1s were gradually replaced by recipient cDC1s. LPS administration increased the number of cDC1s and enhanced their state of activation. We found that Batf3-/- recipient mice experienced reduced acute rejection in response to LPS; in contrast, Batf3-/- donor grafts underwent enhanced lung and skin allograft rejection and drove augmented recipient cluster of differentiation 8+ T-cell expansion in the absence of LPS. Our findings suggest that donor and recipient cDC1s have differing and context-dependent roles and may represent a therapeutic target in lung transplantation.

Application of plasma donor-derived cell free DNA for lung allograft rejection diagnosis in lung transplant recipients

BackgroundDonor-derived cell-free DNA (dd-cfDNA) has been applied to monitor acute rejection (AR) in kidney and heart transplantation. This study was aimed to investigate the application of dd-cfDNA levels in the diagnosis of AR and chronic lung allograft dysfunction (CLAD) among the lung transplantation recipients (LTRs).MethodsOne hundred and seventy LTRs were enrolled at the First Affiliated Hospital of Guangzhou Medical University between 1 June 2015 and 30 March 2021. Patients were divided into 4 groups: stable group, AR group, infection group and CLAD group. The level of dd-cfDNA was analyzed using target region sequencing and the performance characteristics of dd-cfDNA for diagnosis of AR and CLAD were determined, respectively.ResultsKruskal–Wallis test showed that there were some significant differences in the level of dd-cfDNA (%) among the 4 groups, with p < 0.001. Among them, the level of dd-cfDNA (%) was highest (median 2.17, IQR [1.40–3.82]) in AR group, and higher in CLAD group (median 1.07, IQR [0.98–1.31]), but lower in infection group (median 0.71, IQR [0.57–1.07]) and lowest in stable group (median 0.71, IQR [0.61–0.84]). AUC-ROC curve analysis showed that the threshold of dd-cfDNA for AR was 1.17%, with sensitivity being 89.19% and specificity being 86.47%, and the optimal threshold of 0.89% was determined of CLAD, with sensitivity being 95.00% and specificity of 76.99%.ConclusionsPlasma dd-cfDNA could be a useful tool for the assessment of lung allograft rejection, including AR and CLAD, and holds promise as a noninvasive biomarker for “allograft injury” in both acute and chronic rejection following lung transplantation.

Cross-Regulation of F-Box Protein FBXL2 with T-bet and TNF-α during Acute and Chronic Lung Allograft Rejection.

Chronic lung allograft dysfunction is the major barrier to long-term survival in lung transplant recipients. Evidence supports type 1 alloimmunity as the predominant response in acute/chronic lung rejection, but the immunoregulatory mechanisms remain incompletely understood. We studied the combinatorial F-box E3 ligase system: F-box protein 3 (FBXO3; proinflammatory) and F-box and leucine-rich repeat protein 2 (FBXL2; anti-inflammatory and regulates TNFR-associated factor [TRAF] protein). Using the mouse orthotopic lung transplant model, we evaluated allografts from BALB/c → C57BL/6 (acute rejection; day 10) and found significant induction of FBXO3 and diminished FBXL2 protein along with elevated T-bet, IFN-γ, and TRAF proteins 1-5 compared with isografts. In the acute model, treatment with costimulation blockade (MR1/CTLA4-Ig) resulted in attenuated FBXO3, preserved FBXL2, and substantially reduced T-bet, IFN-γ, and TRAFs 1-5, consistent with a key role for type 1 alloimmunity. Immunohistochemistry revealed significant changes in the FBXO3/FBXL2 balance in airway epithelia and infiltrating mononuclear cells during rejection compared with isografts or costimulation blockade-treated allografts. In the chronic lung rejection model, DBA/2J/C57BL/6F1 > DBA/2J (day 28), we observed persistently elevated FBXO3/FBXL2 balance and T-bet/IFN-γ protein and similar findings from lung transplant recipient lungs with chronic lung allograft dysfunction versus controls. We hypothesized that FBXL2 regulated T-bet and found FBXL2 was sufficient to polyubiquitinate T-bet and coimmunoprecipitated with T-bet on pulldown experiments and vice versa in Jurkat cells. Transfection with FBXL2 diminished T-bet protein in a dose-dependent manner in mouse lung epithelial cells. In testing type 1 cytokines, TNF-α was found to negatively regulate FBXL2 protein and mRNA levels. Together, our findings show the combinatorial E3 ligase FBXO3/FBXL2 system plays a role in the regulation of T-bet through FBXL2, with negative cross-regulation of TNF-α on FBXL2 during lung allograft rejection.