Immune response to HLA and non-HLA antigens play a significant role in the development of chronic and acute rejection (AR), bronchiolitis obliterans syndrome (BOS), following human lung transplant (LTx). The goal of this study is to determine whether exosomes are induced during lung allograft rejection and to define its antigenic compositions (HLA, lung associated self-antigens (SAgs)) and microRNAs (miRNAs). Exosomes were isolated from bronchoalveolar lavage (BAL) and sera from LTx recipients (LTxR) diagnosed with AR, BOS, or stable. Specificity of isolated exosomes were defined by flow cytometry and western blot using expression of CD63 and Annexin-V respectively. Expression of SAgs, Collagen-V (Col-V) and Kα1 tubulin (Kα1T), were examined by transmission electron microscopy and HLA by flow cytometry using allele specific Abs. miRNAs were profiled by Affymetrix miRNA array and comparative miRNA pathway analysis were performed with DIANA-mirPath. Differentially expressed miRNA were validated in independent cohorts using qRT-PCR. Donor HLA antigens and SAgs were detected on the surface of exosomes isolated from LTxR diagnosed with AR and BOS, but not in stable, indicating that immune responses can lead to exosome generation and release into body fluids. Exosomes expressing Col-V were isolated from sera of LTxR months prior to diagnosis of AR (3 months) and BOS (6 months) suggesting exosomes with SAgs can be a non-invasive rejection biomarker. The global miRNA analysis demonstrated that there were 123 miRNAs detectable in sera exosomes. Exosomes isolated from sera and BAL from AR and BOS demonstrated significantly higher expression of immunoregulatory miRNAs AR (miR-92a, miR-182) and BOS (miR-92a), miR-182, miR-142-5p, miR-155, compared with stable. Exosomes are induced and released into circulation (sera and BAL) following AR and BOS and isolated exosomes express donor HLA and SAgs (Col-V and Kα1T). Pathway analysis using global miRNA profile demonstrated significant increases in several immunoregulatory miRNAs (miR-92a, miR-182, miR-142-5p, and miR-155) suggesting that released exosomes may play an important role in the immuno-pathogenesis of AR and BOS following human LTx.

CITATION INFORMATION: Gunasekaran M, Xu Z, Nayak D, Sharma M, Hachem R, Mohanakumar T. Exosomes with Lung Associated Self-Antigens (Collagen V and K alpha 1 Tubulin): Role in Rejection Following Human Lung Transplantation. Am J Transplant. 2016;16 (suppl 3).

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