Detection of citrate synthase-reacting autoantibodies after heart transplantation: an epitope mapping study

Abstract

Autoimmune mechanisms play an important role in the pathogenesis of allograft vasculopathy following heart transplantation, but the autoantigens involved have been only sparsely studied. Citrate synthase (CS) enzyme is a conserved molecule, and, as an important mitochondria1 autoantigen, it is protected by the "immunological homunculus". Tissue destruction and alteration of the immune regulatory mechanisms can induce pathological immune response against CS in other autoimmune diseases. In our present study we aimed to detect CS-specific autoantibodies in heart transplant patients, therefore, prospective, randomised clinical tests were conducted on 33 heart transplant patients and compared with -1 30 healthy blood donors. The level and isotype of CS antibodies were detected by simple binding indirect enzyme-linked immunosorbent assay (ELISA). The epitope specificities of the autoantibodies were measured on synthetic overlapping peptide sequences of CS enzyme by an indirect multi-pin ELISA method. Mainly IgM isotype CS autoantibodies were found in healthy controls, while IgG was found at higher levels and frequency (fourtimes higher) in heart transplant patients. Autoantibodies of IgG isotype recognise different epitopes than do autoantibodies of IgM isotype, even within the same group and individual. New epitope-specific IgG and IgM isotype autoantibodies appeared in heart transplant patients when compared with the controls. Our findings suggest a possible role of CS-specific autoantibodies in the pathomechanism of allograft vasculopathy .

Correlation of natural autoantibodies and cardiovascular disease-related anti-bacterial antibodies in pericardial fluid of cardiac surgery patients

“…Relative excess of anti-CS IgM natural autoantibodies in the pericardial fluid CS has been characterized as an autoantigen recognized by the natural immune system in humans. We have documented previously that anti-CS IgM natural antibodies are continuously present in plasma of healthy controls and that anti-CS IgG levels increase in patients with autoimmune diseases and heart transplantation [25,26,35]; however, no data have been published regarding the anti-CS antibodies in PF. The anti-CS IgM and IgG natural autoantibodies were measured by an in-house ELISA developed and validated in our laboratory.…”

Following Natural Autoantibodies: Further Immunoserological Evidence Regarding Their Silent Plasticity and Engagement in Immune Activation

“…As nAAbs, we used anti-citrate synthase (CS) antibodies; CS is a pacemaker enzyme in the Krebs cycle and is commonly used as a quantitative marker enzyme for the content of intact mitochondria [83,84]. As proven by the scientific literature [21,[32][33][34][35][36][37]46,85,86], CS-specific autoantibodies can be considered a prominent example of nAAbs.…”

An autoantigen profile of human A549 lung cells reveals viral and host etiologic molecular attributes of autoimmunity in COVID-19

“… Gene Protein COVID A549 infection Inter-actome DS-affinity AutoAg ref. up down up down 1.0 M 0.5 M 2 A2M Alpha-2-macroglobulin D + [ 54 ] 2 ACLY ATP-citrate synthase U D U D + [ 55 ] 9 ACTA2 Actin, aortic smooth muscle U D U D + [ 56 ] 8 ACTB Actin, cytoplasmic 1 U D U D + [ 57 ] 5 ACTBL2 Beta-actin-like protein 2 U D U D + [ 57 ] 20 ACTN1 Alpha-actinin-1 …”