Dysregulated MicroRNA Expression and Chronic Lung Allograft Rejection in Recipients With Antibodies to Donor HLA.

The pathogenesis of chronic rejection, Bronchiolitis Obliterans Syndrome (BOS) following lung transplantation (LT) is poorly understood. We hypothesized that development of antibodies to HLA (DSA) is associated with dysregulation of microRNA (miRNA) that predisposes BOS. Towards this, miRNA profiling of mononuclear cells from 10 stable LT (DSA(-) BOS(-) ), 10 LT with DSA(+) BOS(-) (DSA group) and 10 LT with DSA(+) BOS(+) (BOS group) were performed. Prediction by mirPath indicated that differential miRNAs in DSA(+) BOS(-) compared to stable are significantly up-regulated (relative fold >2, p < 0.05) for TGF-ß and B cell receptor signal pathways. A total of seventy-four miRNAs were up-regulated and six miRNAs were down regulated in LT with DSA(+) BOS(+) when compared to stable (relative fold >2, p < 0.05). There was also significant enrichment of cell cycle and gap junction pathways. An inverse correlation between expression of two key miRNAs and their target genes were observed: miR-369-5p and miR-548d were down regulated in DSA(+) LT while their gene targets in TGF-ß signal pathways were up-regulated. In addition, miR-628-5p and miR-134 were down regulated and their target genes (B cell development) were up-regulated. Therefore, we conclude that alloimmunity induced changes in miRNAs affecting the TGF-ß and B cell receptor signal pathways play important roles in BOS development.

Antibodies to K-α 1 tubulin and collagen V are associated with chronic rejection after lung transplantation.

Bronchiolitis obliterans syndrome (BOS), the clinical correlate of chronic rejection after lung transplantation, is the leading obstacle to better long-term outcomes. We previously instituted a clinical protocol to screen for donor-specific human leukocyte antigen (HLA) antibodies (DSA) and a preemptive antibody-directed therapy protocol consisting of rituximab and/or intravenous immune globulin. In this study, we retrospectively analyzed serum samples from lung transplant recipients (n = 108) for antibodies to self-antigens (K-α 1 tubulin and collagen V) before and after antibody-directed therapy and correlated the results with the subsequent development of BOS. Seventy-two of the 108 recipients developed antibodies to self-antigens. There was a correlation between the development of antibodies to self-antigens and DSA. Sixteen of the 54 patients who had antibodies to self-antigens and were treated with antibody-directed therapy cleared the antibodies, and they were significantly less likely to develop BOS than those who had persistent antibodies. Furthermore, those who cleared DSA after treatment but had persistent antibodies to self-antigens were significantly more likely to develop BOS than those who cleared these antibodies. We conclude that antibodies to self-antigens are an important risk factor for the development of BOS.

Activation of human airway epithelial cells by non-HLA antibodies developed after lung transplantation: a potential etiological factor for bronchiolitis obliterans syndrome.

BACKGROUND: The main cause of morbidity and mortality after lung transplantation (LT) is bronchiolitis obliterans syndrome (BOS). Anti-HLA antibodies development after LT has been shown to play an important role in BOS pathogenesis. However, the nature of non-HLA antibodies developed after LT and their role in BOS pathogenesis have not been determined. METHODS: Sera from 16 BOS+ patients and 11 BOS- patients were collected at 12, 24, 36, and 48 months after LT. Anti-HLA class I and class II antibodies were absorbed with pooled human platelets and pooled human lymphoblastoid cell lines, respectively. Then, the presence of non-HLA antibodies against several cell lines from different origin was determined by flow cytometric analysis. Antibody-positive samples were tested for induction of proliferation and growth factor production in two selected airway epithelial cell (AEC) lines. RESULTS: Five of 16 BOS+ patients (31.2%) and 0 of 11 BOS- patients (0%) developed anti-AEC antibodies after LT (P=0.05). No reactivity against endothelial cells, lymphocytes, monocytes, or granulocytes was detected. Further analysis of two selected sera demonstrated the development of reactivity against a 60-kDa antigen expressed by 60% of AEC lines and only 12% of cell lines from other tissues. Antibody binding to this antigen induced intracellular Ca++ influx, tyrosine phosphorylation, proliferation, and up-regulation of transforming growth factor-beta and heparin-binding epidermal growth factor mRNA transcription in AECs. CONCLUSIONS: These results indicate that anti-AEC antibodies may play a role in the immunopathogenesis of BOS in the absence of anti-HLA antibodies.