Characterization of immune responses to cardiac self-antigens myosin and vimentin in human cardiac allograft recipients with antibody-mediated rejection and cardiac allograft vasculopathy

Background: Herein we study the role of donor-specific antibodies (DSA) to mismatched human leukocyte antigen (HLA) and antibodies (Abs) to the cardiac self-antigens myosin (MYO) and vimentin (VIM) in the pathogenesis of acute antibody-mediated rejection (AMR) in the early post-transplant period (EP, <12 months) and cardiac allograft vasculopathy (CAV) in the late post-transplant period (LP, >12 months) after heart transplantation (HTx). Methods: One hundred forty-eight HTx recipients (65 in EP, 83 in LP) were enrolled in the study. Development of DSA was determined by Luminex. Circulating Abs against MYO and VIM in sera were measured using enzyme-linked immunoassay (ELISA). Frequency of CD4⁺ T-helper cells (CD4⁺ Th) secreting interferon (IFN)-γ, interleukin (IL)-17, IL-10 or IL-5 specific to either MYO or VIM were analyzed in vitro using ELISpot assays. Results: AMR patients were more likely DSA positive (AMR^-: 15%; AMR⁺: 70%; p = 0.03) and demonstrated increased Abs to MYO (AMR^-: 144 ± 115 μg/ml; AMR⁺: 285 ± 70 μg/ml; p = 0.033) and VIM (AMR^-: 37 ± 19 μg/ml; AMR⁺: 103 ± 43 μg/ml; p = 0.014). AMR patients demonstrated increased IL-5 CD4⁺ Th cells specific to MYO (5.2 ± 0.9 fold, p = 0.003) and VIM (7.3 ± 2.9-fold, p = 0.004) and decreased IL-10 CD4⁺ Th cells specific to MYO (2.2 ± 0.4-fold, p = 0.009) and VIM (1.7 ± 0.2-fold, p = 0.03). CAV patients were more likely DSA positive (CAV ^-: 25%; CAV⁺: 79%; p = 0.03) and demonstrated increased Abs to MYO (CAV^-: 191 ± 120 μg/ml; CAV⁺: 550 ± 98 μg/ml; p = 0.025) and VIM (CAV^-: 55 ± 25 μg/ml; CAV⁺: 255 ± 49 μg/ml; p = 0.001). CAV patients demonstrated increased IL-17 CD4⁺ Th cells specific to MYO (10.5 ± 7.3-fold, p = 0.002) and VIM (7.0 ± 3.9-fold, p = 0.003). Conclusions: The presence of DSA in AMR and CAV is significantly associated with development of Abs to MYO and VIM in post-HTx patients. Induction of high CD4⁺ Th cells specific to cardiac self-antigens that secrete predominantly IL-5 and IL-17 plays a significant role in the development of Abs to self-antigens leading to AMR and CAV, respectively.