Background C-reactive protein (CRP) has 2 natural isomers, C-reactive protein pentamer (pCRP) and C-reactive protein monomer (mCRP). The levels of CRP are significantly elevated in patients with anti-neutrophil cytoplasmic antibody（ANCA)-associated vasculitis (AAV). mCRP not only can cause the activation of endothelial cells, platelets, leukocytes, and complements, but also have a proinflammatory structural subtype that can localise and deposit in inflammatory tissues, so it is an important mediator of a variety of clinical diseases, such as Ischemia/Reis perfusion (I/R) injury, Alzheimer's disease, age-related macular degeneration, and cardiovascular disease. Complications of myocardial infarction occurred（n=4) in 37 AAV patients we collected, so it is speculated that mCRP may be related to cardiovascular disease in patients.
Methods Brain natriuretic peptide (BNP) and mCRP in plasma were tested by enzyme-linked immunosorbent assay (ELISA). The Acute ST-segment elevation myocardial infarction（STEMI) diagnosed by Coronary angiography and then calculated the Gensini score. Echocardiography: ejection fraction （EF%)，left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular mass index (LVMI). Glomerular filtration rate (eGFR) was calculated based on serum creatinine, age, and gender.
Results The plasma levels of mCRP in AAV was significantly higher than that in healthy volunteers (P<0.001). There were 4 STEMI complications in AAV. We compared mCRP and CRP levels with STEMI complication and without STEMI complications in AAV, the plasma levels of mCRP was higher, however the plasma levels of CRP was lower in STEMI. Plasma levels of mCRP correlated with Birmingham vasculitis activity score (BVAS), eGFR, BNP, EF%, LVEDV, LVESV, LVMI ( r =0.404, P =0.013; r =-0.341, P =0.039; r =0.349, P =0.034; r =-0.362, P =0.027; r =0.375, P =0.022; r =0.334, P =0.043; r =0.736, P <0.001) and STEMI complications’ Gensini score (r=0.977, P=0.023) in AAV, however CRP didn’t correlate with BNP, EF%, LVEDV, LVESV, LVMI and Gensini score.
Conclusions The plasma levels of mCRP related to cardiovascular diseases in AAV patients.