The Influence of Anti-PAR 1 and Anti-ACE 2 Antibody Levels on the Course of Specific Glomerulonephritis Types

<b>Background:</b> Anti-PAR 1 (protease-activated receptor 1) and anti-ACE 2 (angiotensin 2-converting enzyme 2) antibodies are a kind of non-HLA (human leukocyte antigens) antibodies postulated to be of significance in autoimmunological diseases and organ transplantation. <b>Methods:</b> We assessed anti-PAR 1 and anti-ACE 2 antibody levels in patients with membranous nephropathy <i>n</i>= 18, focal and segmental glomerulosclerosis (FSGS) <i>n</i> = 25, lupus nephritis (LN) <i>n</i> = 17, IgA nephropathy <i>n</i> = 14, mesangial proliferative (non-IgA) glomerulonephritis <i>n</i> = 6, c-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) vasculitis <i>n</i> = 40, p (perinuclear)-ANCA vasculitis <i>n</i> = 16, and compared them with a healthy control group <i>n</i> = 22. Next, we observed the clinical course of the patients (creatinine, total protein, and albumin) up to 2 years and correlated the results with the level of antibodies. <b>Results:</b> The anti-PAR 1 antibody level was lower in membranous nephropathy and FSGS compared to the control group. Anti-PAR 1 antibody levels were higher in secondary compared to primary glomerulonephritis. Both anti-PAR 1 and anti-ACE 2 antibody levels correlated positively (in focal and segmental glomerulosclerosis) or negatively (in lupus nephritis) with total protein and albumin at different time points of observation. Anti-PAR 1 and anti-ACE 2 antibody levels correlated also with creatinine level at one time point of observation in IgA nephropathy. Anti-PAR 1 and anti-ACE 2 antibodies correlated with each other in membranous nephropathy, FSGS, and p- and c-ANCA vasculitis (<i>p</i> < 0.05). <b>Conclusions:</b> The anti-PAR 1 antibody level was lower in membranous nephropathy and focal and segmental glomerulosclerosis compared to the control group. Anti-PAR 1 antibody levels tend to be higher in secondary compared to primary glomerulonephritis.