Objective:To explore the relationship between the expressions of P21,P27 and proliferating cell nuclear antigen(PCNA)in glomerular mesangial tissue and poor renal prognosis in patients with immunoglobulin A(IgA)nephropathy.Methods:A total of 145 patients with IgA nephropathy treated in Xiaogan Central Hospital from April 2017 to August 2019 were selected as the research object.The expressions of P21,P27 and PCNA in glomerular mesangial tissue were detected by immunohistochemistry.All patients were followed up for 24 months,and the prognosis were counted.The expressions of P21,P27 and PCNA in glomerular mesangial tissue of patients with different prognosis were compared and the influencing factors of poor prognosis in patients with IgA nephropathy were analyzed by Logistic regression analysis.Results:The expression rates of P21,P27 and PCNA positive cells in glomerular mesangial tissue of patients with IgA nephropathy were(38.69±6.83)%,(55.94±8.08)%,(33.47±5.72)%,respectively.The incidence rete of poor prognosis in patients with IgA nephropathy was 17.24%,and the expression rates of P21 and PCNA positive cells in glomerular mesangial tissue of patients with poor prognosis were higher than those in good prognosis group(P<0.05),while the expression rate of P27 positive cells was lower than that in good prognosis group(P<0.05).Logistic multiple regression analysis showed that elevated diastolic blood pressure,increased 24 h proteinuria,mesangial cell proliferation,segmental glomerulosclerosis,renal tubular atrophy/interstitial fibrosis,crescentic body,increased expression rates of P21 and PCNA positive cells and decreased expression rate of P27 positive cells were all risk factors affecting the poor prognosis of patients with IgA nephropathy(P<0.05).Conclusion:There are positive expressions of P21,P27 and PCNA in glomerular mesangial tissue of IgA nephropathy.The expression rates of P21 and PCNA positive cells in glomerular mesangial tissue of of patients with poor prognosis of IgA nephropathy are higher than those with good prognosis,while the expression rate of P27 protein positive cells is lower than those with good prognosis,which are risk factors for poor prognosis of patients with IgA nephropathy.