Risk Of Chronic Lung Allograft Dysfunction Research Articles

Identification and Validation of a Threshold for Early Posttransplant Bronchoalveolar Fluid Hyaluronan that Distinguishes Lung Recipients at Risk for CLAD

BackgroundFew tools exist for early identification of patients at risk for chronic lung allograft dysfunction (CLAD). We previously showed hyaluronan (HA), a matrix molecule that regulates lung inflammation and fibrosis, accumulates in bronchoalveolar lavage fluid (BALF) and blood in CLAD. We aimed to determine if early posttransplant HA elevations inform CLAD risk. MethodsHA was quantified in 3080 BALF and 1323 blood samples collected over the first posttransplant year in 743 adult lung recipients at 5 centers. The relationship between BALF or blood HA and CLAD was assessed using Cox models with a time-dependent binary covariate for “elevated” HA. Potential thresholds for elevated HA were examined using a grid search between the 50th and 85th percentile. The optimal threshold was identified using fit statistics, and the association between the selected threshold and CLAD was internally validated through iterative resampling. A multivariable Cox model using the selected threshold was performed to evaluate the association of elevated HA with CLAD considering other factors that may influence CLAD risk. ResultsBALF HA levels >19.1ng/mL (65th percentile), had the largest hazard ratio for CLAD (HR 1.70, 95% CI 1.25–1.31; p<0.001), optimized fit statistics, and demonstrated robust reproducibility. In a multivariable model, the occurrence of BALF HA >19.1 ng/mL in the first posttransplant year conferred a 66% increase in the hazards for CLAD (adjusted HR 1.66, 95% CI 1.19–2.32; p=0.003). Blood HA was not significantly associated with CLAD. ConclusionsWe identified and validated a precise threshold for BALF HA in the first posttransplant year that distinguishes patients at increased CLAD risk.

Mitigating the risk of inflammatory type primary graft dysfunction by applying an integrated approach to assess, modify and match risk factors in lung transplantation.

Long-term outcome following lung transplantation remains one of the poorest of all solid organ transplants with a 1- and 5-year survival of 85% and 59% respectively for adult lung transplant recipients and with 50% of patients developing chronic lung allograft dysfunction (CLAD) in the first 5 years following transplant. Reducing the risk of inflammatory type primary graft dysfunction (PGD) is vital for improving both short-term survival following lung transplantation and long-term outcome due to the association of early inflammatory-mediated damage to the allograft and the risk of CLAD. PGD has a multifactorial aetiology and high-grade inflammatory-type PGD is the result of cumulative insults that may be incurred in one or more of the three variables of the transplantation continuum: the donor lungs, the recipient and intraoperative process. We set out a conceptual framework which uses a fully integrated approach to this transplant continuum to attempt to identify and, where possible, modify specific donor, recipient and intraoperative PGD risk with the goal of reducing inflammatory-type PGD risk for an individual recipient. We also consider the concept and risk-benefit of matching lung allografts and recipients on the basis of donor and recipient PGD-risk compatibility. The use of ex vivo lung perfusion (EVLP) and the extended preservation of lung allografts on EVLP will be explored as safe, non-injurious EVLP may enable extensive inflammatory testing of specific donor lungs and has the potential to provide a platform for targeted therapeutic interventions on lung allografts.

Immunomodulatory soluble HLA-G and HLA-E are associated with rapidly deteriorating CLAD and HCMV viremia after lung transplantation

Plasma-soluble (s)HLA-G and sHLA-E are immunoregulatory proteins that balance the activation of NKG2A+ immune cells. In lung-transplant recipients (LTRs), dysregulated NKG2A+ natural killer cell responses may result in high-level HCMV replication as well as chronic lung allograft dysfunction (CLAD), and especially the development of rapidly deteriorating CLAD is associated with high mortality. We thus analyzed the kinetics and function of sHLA-G and sHLA-E in follow-up samples of N=76 LTRs to evaluate whether these immunoregulatory proteins are associated with the risk for CLAD and high-level HCMV replication. Here, we demonstrate that rapidly deteriorating CLAD LTRs are hallmarked by continually low (<107 ng/mL) sHLA-G levels. In contrast, high sHLA-E levels were associated with the following development of high-level (>1000 copies/mL) HCMV episodes. Thus, sHLA-G and sHLA-E may serve as novel biomarkers for the development of rapidly deteriorating CLAD and high-level HCMV replication in LTRs.

Specific human leucocyte antigen-DQ risk epitope mismatches are associated with chronic lung allograft dysfunction after lung transplantation

A high-risk epitope mismatch (REM) (found in DQA1∗05 + DQB1∗02/DQB1∗03:01) is associated with de novo donor specific antibodies after lung transplantation (LTx). Chronic lung allograft dysfunction (CLAD) remains a barrier to LTx survival. This study aimed to measure the association between DQ REM and the risk of CLAD and death after LTx. A retrospective analysis of LTx recipients at a single center was conducted between January 2014 and April 2019. Molecular typing at human leucocyte antigen-DQA/DQB identified DQ REM. Multivariable competing risk and Cox regression models were used to measure the association between DQ REM, time-to-CLAD, and time-to-death. DQ REM was detected in 96/268 (35.8%), and DQ REM de novo donor specific antibodies were detected in 34/96 (35.4%). CLAD occurred in 78 (29.1%), and 98 (36.6%) recipients died during follow-up. When analyzed as a baseline predictor, DQ REM status was associated with CLAD (subdistribution hazard ratio (SHR), 2.19; 95% confidence interval [CI], 1.40-3.43; P = .001). After adjustment for time-dependent variables, DQ REM dn-DSA (SHR, 2.43; 95% CI, 1.10-5.38; P = .029) and A-grade rejection score (SHR, 1.22; 95% CI, 1.11-1.35; P = <.001), DQ REM status was not independently associated with CLAD. DQ REM was not associated with death (hazard ratio, 1.18; 95% CI, 0.72-1.93; P = .51). Classification of DQ REM may identify patients at risk of poor outcomes and should be incorporated into clinical decision-making.

IL-33 mediates Pseudomonas induced airway fibrogenesis and is associated with CLAD.

Long term outcomes of lung transplantation are impacted by the occurrence of chronic lung allograft dysfunction (CLAD). Recent evidence suggests a role for the lung microbiome in the occurrence of CLAD, but the exact mechanisms are not well defined. We hypothesize that the lung microbiome inhibits epithelial autophagic clearance of pro-fibrotic proteins in an IL-33 dependent manner, thereby augmenting fibrogenesis and risk for CLAD. Autopsy derived CLAD and non-CLAD lungs were collected. IL-33, P62 and LC3 immunofluorescence was performed and assessed using confocal microscopy. Pseudomonas aeruginosa (PsA), Streptococcus Pneumoniae (SP), Prevotella Melaninogenica (PM), recombinant IL-33 or PsA-lipopolysaccharide was co-cultured with primary human bronchial epithelial cells (PBEC) and lung fibroblasts in the presence or absence of IL-33 blockade. Western blot analysis and quantitative reverse transcription (qRT) PCR was performed to evaluate IL-33 expression, autophagy, cytokines and fibroblast differentiation markers. These experiments were repeated after siRNA silencing and upregulation (plasmid vector) of Beclin-1. Human CLAD lungs demonstrated markedly increased expression of IL-33 and reduced basal autophagy compared to non-CLAD lungs. Exposure of co-cultured PBECs to PsA, SP induced IL-33, and inhibited PBEC autophagy, while PM elicited no significant response. Further, PsA exposure increased myofibroblast differentiation and collagen formation. IL-33 blockade in these co-cultures recovered Beclin-1, cellular autophagy and attenuated myofibroblast activation in a Beclin-1 dependent manner. CLAD is associated with increased airway IL-33 expression and reduced basal autophagy. PsA induces a fibrogenic response by inhibiting airway epithelial autophagy in an IL-33 dependent manner.

Plasma CXCL9 and CXCL10 at allograft injury predict chronic lung allograft dysfunction

Histopathologic lung allograft injuries are putative harbingers for chronic lung allograft dysfunction (CLAD). However, the mechanisms responsible are not well understood. CXCL9 and CXCL10 are potent chemoattractants of mononuclear cells and potential propagators of allograft injury. We hypothesized that these chemokines would be quantifiable in plasma, and would associate with subsequent CLAD development. In this prospective multicenter study, we evaluated 721 plasma samples for CXCL9/CXCL10 levels from 184 participants at the time of transbronchial biopsies during their first-year post-transplantation. We determined the association between plasma chemokines, histopathologic injury, and CLAD risk using Cox proportional hazards models. We also evaluated CXCL9/CXCL10 levels in bronchoalveolar lavage (BAL) fluid and compared plasma to BAL with respect to CLAD risk. Plasma CXCL9/CXCL10 levels were elevated during the injury patterns associated with CLAD, acute rejection, and acute lung injury, with a dose-response relationship between chemokine levels and CLAD risk. Importantly, there were strong interactions between injury and plasma CXCL9/CXCL10, where histopathologic injury associated with CLAD only in the presence of elevated plasma chemokines. We observed similar associations and interactions with BAL CXCL9/CXCL10 levels. Elevated plasma CXCL9/CXCL10 during allograft injury may contribute to CLAD pathogenesis and has potential as a minimally invasive immune monitoring biomarker.

The Normalised Acute Rejection Score in the First Year Post Transplant and Its Association with CLAD

<h3>Purpose</h3> The Acute Rejection Score (A-score) is a measure of the burden of acute cellular rejection (ACR) over time in lung transplant (Ltx) recipients which is often incorporated into multivariate analyses assessing LTx outcomes. We aim to assess the correlation between A-score at 6 and 12 months post Ltx and chronic lung allograft dysfunction (CLAD). <h3>Methods</h3> We performed a retrospective cohort analysis on adult 1^st double LTx recipients from January 2003 to March 2018, with minimum 6 months of follow-up and 1 or more evaluable transbronchial biopsies (TBBX) in the 1^st year post Ltx. A-score was calculated at 6 months (approximated as 210 days) and 1 year (400 days) post-LTx as the sum of all ACR histologic A-grades, divided by the number of TBBX up to that time point. AX grade biopsies were excluded from the calculation. CLAD was determined according to 2019 ISHLT guidelines. Kaplan-Meier curves were compared using the Log-Rank test. <h3>Results</h3> Of 828 1^st double lung transplants, 31 were excluded with less than 6 months of follow-up and 23 had no evaluable biopsies in the first year post Ltx (final n=774). Mean follow-up was 2102 days to graft failure (death or retransplant) or last available pulmonary function test. 345 patients (45%) developed CLAD. Mean A-score was 0.37 and 0.32 at 210 and 400 days, respectively; median non-zero A-score was 0.5 and 0.4. Kaplan-Meier curves comparing A-score 0 with scores above and below the median were not significantly different (p=0.08 and 0.78 for 210 and 400 days) (Figure A,B). Log-rank comparison of only non-zero groups was not significant (p=0.78 and 0.93 at 210 and 400 days). <h3>Conclusion</h3> A-score at 210 and 400 days post Ltx, when setting a cutoff at the median, is not significantly associated with CLAD. Further study with Cox proportional hazard modelling of the A-score as a continuous and time-dependent variable will be conducted to assess the impact on the risk of CLAD.

Azithromycin Prophylaxis after Lung Transplantation is Associated with Improved Survival and Graft Function

Azithromycin prophylaxis (AP) has been shown in a clinical trial to reduce the cumulative incidence of death or chronic lung allograft dysfunction (CLAD) onset in lung transplant recipients. However, there has been a lack of follow-up data on the long-term efficacy of this strategy in larger cohorts. Our program began using AP in 2010. Our objective was to evaluate the association between AP survival as well as CLAD and baseline lung allograft dysfunction (BLAD). We hypothesized that patients receiving AP would show equivalent survival and but reduced rates of CLAD and BLAD. We studied all double lung transplant recipients transplanted in our program between 2004-2016. We defined AP as any use of azithromycin prior to CLAD onset. The primary endpoint was death or retransplantation. We defined CLAD status, grade and subtype according to the 2019 ISHLT consensus criteria and BLAD in accordance with our previous published definition. We analyzed survival using proportional hazards regression with AP as a time-varying covariate, adjusting for recipient age, gender, transplant type, underlying diagnosis, year of transplant and induction. We used logistic regression to assess the relationship between AP and baseline allograft dysfunction (BLAD), defined as a failure to achieve both FEV1 and FVC ≥80% predicted on 2 consecutive tests ≥3 weeks apart. 445 patients were included and 344 (77%) were given AP with median time to azithromycin of 51 days [25th-75th quartile 20-211]. Patients receiving AP were more likely to receive induction with IL-2 receptor antagonists (57% vs. 35%; p<0.001) and had shorter mechanical ventilation (54 [29-150] vs. 96 [48-245] hours; p<0.001) and hospital stay (23 [18-36] days vs. 29 [19-44] days; p=0.016). AP was associated with improved survival (hazard ratio [HR] 0.60 [95% confidence interval [CI] 0.44-0.84]; p=0.002) in our adjusted model, as well as a reduced risk of CLAD onset (HR 0.64 [95% CI 0.44-0.94]; p=0.025) and reduced risk for BLAD (odds ratio 0.55 [95% CI 0.35-0.86]; p=0.009) in unadjusted models. Azithromycin prophylaxis is associated with improved survival after lung transplantation, possibly through improved baseline function and a reduced CLAD risk. This corroborates prior trial results, and suggest AP implementation would be beneficial for lung transplant recipients.

A Functional Polymorphism in C3 is Associated with Worse CLAD-Free Survival

Excessive activation of the complement system has been associated with fibrosis and other adverse outcomes in multiple organ systems. We hypothesized that lung transplant (LTx) recipients with a genetic predisposition to complement activation would be at increased risk for chronic lung allograft dysfunction (CLAD). We conducted a retrospective study of adult primary LTx recipients from 2008-2015 at Barnes-Jewish Hospital. Genotyping was done using the Taqman assay on salivary DNA for rs2230199, a known functional polymorphism (C3R102G, minor allele frequency (C)=15%), which is associated with more efficient complement activation on hemolysis assays. Our primary outcome was CLAD-free survival. Analysis included Kaplan-Meier curves with Chi-Square testing, and a multivariable Cox regression model for CLAD-free survival. External validation was conducted in LTx recipients at the University of California, San Francisco. 176 patients were included. 111 (63%) had wild-type C3 (G/G), whereas 64 (36%) had the C3R102G polymorphism (57 - C/G, 7 - C/C). C3R102G was associated with increased risk for CLAD (HR 2.71, 95% CI 1.27 - 5.79, p= 0.01). There was no increased risk for primary graft dysfunction or acute cellular rejection. In a multivariable Cox-proportional hazards model including age, sex, race, LTx type, and pre-LTx diagnosis, C3R102G was associated with increased risk of the composite outcome (CLAD or death, Figure). In the validation cohort, C3R102G remained a significant risk factor for this composite outcome on multivariable analysis (n=322, aHR 1.5, 95% CI 1.03 - 2.2, p=0.03). In a subgroup analysis in both cohorts, C3R102G remained a significant risk factor for CLAD or death when accounting for age, lung allocation score, post-LTx Gram-negative infection and donor-specific antibodies. In two independent cohorts, recipient C3R102G risk alleles are associated with worse CLAD-free survival. These findings support a mechanistic link between complement activation and CLAD.

The Impact of Inadequate ("AX") Transbronchial Biopsies on Post-lung Transplant CLAD or Death.

Procuring a good quality transbronchial-biopsy sample is essential for diagnosing acute cellular rejection after lung transplantation (LT). Insufficient transbronchial-biopsy samples are graded "AX." We hypothesized that AX samples may be associated with a higher risk for chronic lung allograft dysfunction (CLAD) or death/retransplant, through a potential anatomic or physiologic underlying pulmonary process or because of undiagnosed acute cellular rejection episodes. We conducted a single-center, retrospective, cohort study drawn from all consecutive adult, first, bilateral LT between 1999 and 2015. We reviewed all biopsies obtained within the first year posttransplant and compared outcomes of patients with ≥1 AX to patients with no AX. Association of any AX or percent AX with time to CLAD or death/retransplant was assessed using Cox Proportional Hazards models. The cohort consisted of 809 patients with a median of 6 (interquartile range 5-6) biopsies and 16.7% (interquartile range 0-25) AX samples within the first year posttransplant. Four hundred thirty-nine (54.3%) subjects had ≥1 AX sample obtained within the time period. Median time to CLAD or death/retransplant, from 1 year posttransplant, was 761 (320, 1587) and 1200 (662, 2308) days, respectively. In the multivariable analysis, there was no difference in risk for CLAD (hazard ratio = 1.05, 95% confidence interval, 0.87-1.28, P = 0.60), or death/retransplant (hazard ratio = 1.14, 95% confidence interval, 0.92-1.42, P = 0.24) between patients with ≥1 AX biopsy versus none. Among subjects with ≥1 AX, having >50% AX biopsies was not associated with outcome. This is the first study to demonstrate that AX biopsies are not associated with an increased risk of CLAD or death/retransplant after LT and may not require to repeat the biopsy.

The impact of first untreated subclinical minimal acute rejection on risk for chronic lung allograft dysfunction or death after lung transplantation.

Acute cellular rejection (ACR) is a significant risk factor for chronic lung allograft dysfunction (CLAD). Although clinically manifest and higher grade (≥A2) ACR is generally treated with augmented immunosuppression, management of minimal (grade A1) ACR remains controversial. In our program, patients with subclinical and spirometrically stable A1 rejection (StA1R) are routinely not treated with augmented immunosuppression. We hypothesized that an untreated first StA1R does not increase the risk of CLAD or death compared to episodes of spirometrically stable no ACR (StNAR). The cohort was drawn from all consecutive adult, first, bilateral lung transplantations performed between 1999 and 2017. Biopsies obtained in the first-year posttransplant were paired with (forced expiratory volume in 1second FEV1 ). The first occurrence of StA1R was compared to a time-matched StNAR. The risk of CLAD or death was assessed using univariable and multivariable Cox proportional hazards models. The analyses demonstrated no significant difference in risk of CLAD or death in patients with a first StA1R compared to StNAR. This largest study to date shows that, in clinically stable patients, an untreated first A1 ACR in the first-year posttransplant is not significantly associated with an increased risk for CLAD or death. Watchful-waiting approach may be an acceptable tactic for stable A1 episodes in lung transplant recipients.

Early Identification of Chronic Lung Allograft Dysfunction: The Need of Biomarkers

A growing number of patients with end-stage lung disease have benefited from lung transplantation (LT). Improvements in organ procurement, surgical techniques and intensive care management have greatly increased short-term graft survival. However, long-term outcomes remain limited, mainly due to the onset of chronic lung allograft dysfunction (CLAD), whose diagnosis is based on permanent loss of lung function after the development of irreversible lung lesions. CLAD is associated with high mortality and morbidity, and its exact physiopathology is still only partially understood. Many researchers and clinicians have searched for CLAD biomarkers to improve diagnosis, to refine the phenotypes associated with differential prognosis and to identify early biological processes that lead to CLAD to enable an early intervention that could modify the inevitable degradation of respiratory function. Donor-specific antibodies are currently the only biomarkers used in routine clinical practice, and their significance for accurately predicting CLAD is still debated. We describe here significant studies that have highlighted potential candidates for reliable and non-invasive biomarkers of CLAD in the fields of imaging and functional monitoring, humoral immunity, cell-mediated immunity, allograft injury, airway remodeling and gene expression. Such biomarkers would improve CLAD prediction and allow differential LT management regarding CLAD risk.

Lung Bile Acid as Biomarker of Microaspiration and Its Relationship to Lung Inflammation

Purpose Gastroesophageal reflux disease (GERD) is thought to expose the lungs to refluxed gastric contents leading to injury and chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Prior small studies showed correlations between lung bile acids and CLAD/survival. The goal of this study was to determine whether bile acid levels in the bronchoalveolar lavage (BAL) correlate with GERD, concurrent lung allograft inflammation, or development of CLAD. Methods The cohort consisted of 25 GERD-positive and 50 GERD-negative adult sequential LTRs who underwent 24h pH/impedance reflux testing and BAL collection within 6 months post-transplant. Bile acids - taurocholic acid (TCA), glycocholic acid (GCA), and cholic acid (CA) - were measured using LC-MS/MS mass spectrometry; 10 cytokines were quantified using a multiplex assay. Levels were compared between groups using generalized linear models. Spearman correlations between biomarkers were assessed. The relationship between biomarkers and time to CLAD was examined using Cox proportional hazards models. Results TCA was significantly higher in BALs of GERD-positive patients compared to GERD-negative (0.4 vs. 0.1, p=0.04), with no significant differences in GCA, CA, or cytokines. Importantly, there were correlations (adjusted for 10 multiple comparisons) between TCA and GCA and inflammatory markers IL-6, CXCL8, CCL2, IL-1β, CCL5, IL-1α, and IL-12p70 (Fig 1A). Additionally, TCA (HR 1.37, p=0.04), IL-6 (HR 1.59, p=0.012), S100A8 (HR 1.39, p=0.033), and CCL2 (HR 1.41, p=0.03) at the time of the BAL were significantly associated with time to CLAD, independent of GERD status (Fig 1B shows additional Kaplan-Meier analysis). Conclusion BAL TCA correlates with GERD, concurrent innate immune inflammation, as well as risk of CLAD. We propose that BAL TCA levels, in conjunction with inflammatory marker measurements, may be useful in identifying LTRs with chronic aspiration of enteric contents that have a higher risk of subsequent adverse outcomes.

Regulatory T Cells in Asymptomatic ISHLT Grade A1 Rejection and the Risk of Chronic Lung Allograft Dysfunction

Purpose Chronic lung allograft dysfunction (CLAD) is the main obstacle to long-term survival after lung transplantation . Predictive biomarkers for CLAD are required for future studies and clinical interventions. Transbronchial biopsy (TBBx) tissue in patients with asymptomatic minimal (ISHLT grade A1) acute cellular rejection , which is not treated, affords an opportunity to study the content of rejection lesions as a determinant of subsequent clinical events. We examined the ratio of regulatory T cells (Tregs, which express Foxp3) to T effector cells (Teff) in TBBx as a predictor of outcome. We hypothesized that higher Treg content in A1 lesions would indicate a lower risk of subsequent acute rejection and CLAD. Methods We identified 10 patients who developed early CLAD ( formalin fixed paraffin embedded sections from each TBBx were stained via immunofluorescence for CD3 to detect T cells, and FoxP3 to detect Tregs. The proportion of Foxp3+ nuclei in 10 random clusters of CD3+ cells was determined using ImageJ software and analyzed with GraphPad Prism. Results Contrary to our hypothesis, we observed a higher content of FoxP3+ cells in those with early onset CLAD relative to those who remained CLAD-free for 5 years (Fig 1). Additionally, those with fewer than 3.12% FoxP3+ cells tended to have longer CLAD-free survival (Fig 2). Subsequent acute rejection did not differ between the groups. Conclusion A higher content of Foxp3+ cells in first asymptomatic A1 lesions may predict increased CLAD risk. Additionally, a similar rate of subsequent acute rejection episodes in the two groups suggests Treg infiltration has a greater influence on chronic rather than acute alloimmune responses. Our findings may reflect increased T cell activity in those with early CLAD relative to those who remained CLAD-free.

B Cells Drive Chronic Lung Allograft Rejection after Ischemia-Reperfusion Injury in Mouse Lung Transplantation

Purpose Chronic lung allograft dysfunction (CLAD) is the primary obstacle to long-term survival after lung transplantation (LTX). Ischemia-reperfusion injury (IRI) increases the risk of CLAD in humans but the underlying mechanisms are not well understood. In a mouse minor alloantigen mismatched LTX model (C57BL/10 [B10] →C57BL/6 [B6]), we observed that IRI augments formation of B cell-rich tertiary lymphoid organs (TLOs) and chronic rejection in allografts but not isografts. We therefore hypothesized that B cells may link IRI with chronic rejection. Methods B10→B6 LTX with extended graft preservation (6 hours at 4°C followed by 45 minutes at 37°Cand 15 minutes at room temperature during anastomosis), which augments acute rejection, fibrosis, and TLO formation, was employed. Anti-CD20 antibody (aCD20: n=9) or isotype control (Iso: n=10) were given i.p. on days -2, +2, +7, +14, and +21. Peripheral blood was longitudinally assessed by flow cytometry after LTX. Grafts were assessed with histology, flow cytometry and immunofluorescence 28 days after LTX. Results aCD20 treatment effectively depleted CD19+ or B220+ B cells in peripheral blood (Figure A) and lung grafts (Figure B). Acute rejection (ISHLT A grade), peribronchial fibrosis, and airways with obliterative bronchiolitis (%OB) were lower in aCD20 mice (1.8, 1.4, and 13.1% respectively) than in Iso mice (3.1, 2.6, and 46.7% respectively) (Figure C). TLOs containing CD3+, CD19+, and peripheral node addressin (PNAd)+cells were also reduced (Figure D). Conclusion In this model of IRI-augmented chronic rejection, B cell depletion attenuated acute rejection, airway fibrosis, and lymphoid neogenesis. Our observations suggest that B cell activation and recruitment may be directly involved in the augmentation of CLAD in LTX recipients experiencing IRI.

Graft Loss and CLAD-Onset Is Hastened by Viral Pneumonia After Lung Transplantation.

Community-acquired respiratory virus (CARV) infections occur frequently after lung transplantation and may adversely impact outcomes. We hypothesized that while asymptomatic carriage would not increase the risk of chronic lung allograft dysfunction (CLAD) and graft loss, severe infection would. All lung transplant cases between January 2000 and July 2013 performed at our center were reviewed for respiratory viral samples. Each isolation of virus was classified according to clinical level of severity: asymptomatic, symptomatic without pneumonia, and viral pneumonia. Multivariate Cox modeling was used to assess the impact of CARV isolation on progression to CLAD and graft loss. Four thousand four hundred eight specimens were collected from 563 total patients, with 139 patients producing 324 virus-positive specimens in 245 episodes of CARV infection. Overall, the risk of CLAD was elevated by viral infection (hazard ratio [HR], 1.64; P < 0.01). This risk, however, was due to viral pneumonia alone (HR, 3.94; P < 0.01), without significant impact from symptomatic viral infection (HR, 0.97; P = 0.94) nor from asymptomatic viral infection (HR, 0.99; P = 0.98). The risk of graft loss was not increased by asymptomatic CARV infection (HR, 0.74; P = 0.37) nor symptomatic CARV infection (HR, 1.39; P = 0.41). Viral pneumonia did, however, significantly increase the risk of graft loss (HR, 2.78; P < 0.01). With respect to CARV, only viral pneumonia increased the risk of both CLAD and graft loss after lung transplantation. In the absence of pneumonia, respiratory viruses had no impact on measured outcomes.

CXCR3 Ligands Are Associated with the Continuum of Diffuse Alveolar Damage to Chronic Lung Allograft Dysfunction

After lung transplantation, insults to the allograft generally result in one of four histopathologic patterns of injury: (1) acute rejection, (2) lymphocytic bronchiolitis, (3) organizing pneumonia, and (4) diffuse alveolar damage (DAD). We hypothesized that DAD, the most severe form of acute lung injury, would lead to the highest risk of chronic lung allograft dysfunction (CLAD) and that a type I immune response would mediate this process. Determine whether DAD is associated with CLAD and explore the potential role of CXCR3/ligand biology. Transbronchial biopsies from all lung transplant recipients were reviewed. The association between the four injury patterns and subsequent outcomes were evaluated using proportional hazards models with time-dependent covariates. Bronchoalveolar lavage (BAL) concentrations of the CXCR3 ligands (CXCL9/MIG, CXCL10/IP10, and CXCL11/ITAC) were compared between allograft injury patterns and "healthy" biopsies using linear mixed-effects models. The effect of these chemokine alterations on CLAD risk was assessed using Cox models with serial BAL measurements as time-dependent covariates. There were 1,585 biopsies from 441 recipients with 62 episodes of DAD. An episode of DAD was associated with increased risk of CLAD (hazard ratio, 3.0; 95% confidence interval, 1.9-4.7) and death (hazard ratio, 2.3; 95% confidence interval, 1.7-3.0). There were marked elevations in BAL CXCR3 ligand concentrations during DAD. Furthermore, prolonged elevation of these chemokines in serial BAL fluid measurements predicted the development of CLAD. DAD is associated with marked increases in the risk of CLAD and death after lung transplantation. This association may be mediated in part by an aberrant type I immune response involving CXCR3/ligands.