What Lies beneath: Preformed Autoantibodies and Lung Transplantation

Self-reactive antibodies associated with bronchiolitis obliterans syndrome subtype of chronic lung allograft dysfunction

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) remains the major limitation in long term survival after lung transplantation. Our objective is to evaluate for the presence of autoantibodies to self-antigens, which is a pathway along with complex interplay with immune as well as non-immune mechanisms that leads to a fibroproliferative process resulting in CLAD.

METHODS

Serum profiles of IgG autoantibodies were evaluated using customized proteomic microarray with 124 antigens. Output from microarray analyzed as antibody scores is correlated with bronchiolitis obliterans (BOS) subtype of CLAD using Mann-Whitney U test or Fisher exact test. Autoantibodies were evaluated for their predictive value for progressive BOS using a Cox proportional hazard model. BOS free survival and overall survival was analyzed using Kaplan-Meier survival analysis.

RESULTS

Forty- two patients included in the study are grouped into "stable BOS" and "progressive BOS" for comparisons. Pulmonary fibrosis is the major indication for lung transplantation in our cohort. Progressive BOS group had significantly worse survival (p < 0.005). Sixteen IgG autoantibodies are significantly elevated at baseline in progressive BOS group. Six among them correlated with worse BOS free survival (p < 0.05). In addition, these six IgG autoantibodies remain elevated at three months and one year after lung transplantation.

CONCLUSION

Pre-existing IgG autoantibodies correlate with progressive BOS and survival in a single center, small cohort of lung transplant recipients. Further validation with larger sample size, external cohort and confirmation with additional tissue, bronchoalveolar lavage samples are necessary to confirm the preliminary findings in our study.

Pre-existing self-reactive IgA antibodies associated with primary graft dysfunction after lung transplantation

BACKGROUND

Primary graft Dysfunction (PGD) results in significant mortality and morbidity after lung transplantation (LT). The objective of this study was to evaluate if pre-existing antibodies to self-antigens in sera of LT recipients are associated with PGD.

METHODS

The serum profiles of IgG and IgA autoantibodies were analyzed using a customized proteomic microarray bearing 124 autoantigens. Autoantibodies were analyzed using Mann-Whitney U test or Fisher exact test. The association of the autoantibodies with clinical phenotypes and survival was analyzed by Kaplan-Meier Survival Analysis. Receiver operating curve characteristics (ROC) were calculated to evaluate the predictive value of the autoantibodies for PGD.

RESULTS

51 patients were included in this study. Autoantigen microarray analysis on the pre-transplantation samples identified 17 IgA and 3 IgG autoantibodies which were significantly higher in recipients who developed PGD compared to those who did not (adjusted p < .05 and fold change>1.5). 6 IgA Abs were significantly associated with survival. Taken as a panel, an elevation of 6 IgA Abs had significant predictive value for PGD. Area under the curve value for the panel was 0.9413 for PGD with ROC analysis. Notably, 6 of the 17 IgA autoantigen targets are belong to proteoglycan family of extracellular matrix proteins.

CONCLUSION

Pre-existing IgG and IgA autoantibodies in LT patients correlate with PGD and with survival in a single center, small cohort of lung transplant recipients. Further validation is needed to confirm the findings in the study.

Prevalence of antibodies to lung self-antigens (Kα1 tubulin and collagen V) and donor specific antibodies to HLA in lung transplant recipients and implications for lung transplant outcomes: Single center experience

PURPOSE

For patients with end stage lung disease, lung transplantation (LT) remains the only definitive treatment option. Long term survival post LT is limited by acute and chronic allograft dysfunction. Antibodies to lung self-antigens Kα1Tubulin and collagen V (autoantibodies) have been implicated in adverse outcomes post LT. The aim of our study was to determine the prevalence of autoantibodies in pre- and post-transplant sera, evaluate the impact on post-transplant outcomes.

METHODS

In a prospective observational cohort analysis, 44 patients were enrolled who received LT between 09/01/2014 and 10/31/2015. Pre- and post-transplant sera were analyzed using enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies to collagen I, collagen V, and K-alpha 1 tubulin. The outcome variables are presence of primary graft dysfunction (PGD), cumulative acute cellular rejection (ACR), treatment with pulse steroids for clinical rejection, association with DSA, and onset of Bronchiolitis Obliterans Syndrome (BOS).

RESULTS

In our cohort, 33 patients (75%) tested positive for the presence of autoantibodies. Pre-transplant autoantibodies were present in 23 patients (70%). Only a small percentage (26%) cleared these antibodies with standard immunosuppression. Some developed de novo post-transplant (n = 10). PGD was observed in 34% of our cohort, however the presence of autoantibodies did not correlate with increase in the incidence or severity of PGD. The prevalence of donor specific antibodies (DSA) in the entire cohort was 73%, with an increased prevalence of DSA noted in the autoantibody positive group (78.7% vs. 54.5%) than in the autoantibody negative group. BOS was observed in 20% of the cohort, with a median time to onset of 291 days' post-transplant. Patients with pre-transplant autoantibodies had a statistically significant decrease in BOS-free survival (p = 0.029 by log-rank test).

CONCLUSIONS

In our cohort, we observed a high prevalence of autoantibodies and DSA in lung transplant recipients. Pre-transplant autoantibodies were associated with de novo development of DSA along with a decrease in BOS-free survival. Limitations to our study include the small sample size and single center enrollment, along with limited time for follow-up.