Dendritic cell and M2 macrophages are associated with the severity of disease in IgA nephropathy patients

Objective To investigate the number and distribution of dendritic cells (DCs), macrophages and M2 macrophages in renal tissues of patients with IgA nephropathy (IgAN) and their correlation with clinicopathological parameters, and explore its role in the progression of IgAN. Methods Renal tissue samples from 42 patients aged ≥18 years with IgAN were collected by kidney biopsy in Guangdong Provincial People's Hospital from January 2018 to June 2018. The patients were divided into different groups according to Oxford classification and Lee grade classification criteria. The distribution and number of DCs (CD209), macrophages (CD68) and M2 macrophages (CD68 and CD206) were detected by immunohistochemistry. Spearman correlation test was used to analyze the correlation between the number of DCs and macrophages in renal tissues and clinical pathological parameters. Results The number of DCs in the glomeruli of the M1, T0 and C1 groups increased significantly compared with the M0, T1 and C0 groups, and the number of DCs in the renal interstitium of the T1 group increased significantly compared with the T0 group (all P<0.05). The number of glomerular macrophages in group C1 was significantly higher than that in group C0. The number of macrophages in S1, T1 and Lee IV-V tubulointerstitial groups was significantly higher than that in S0, T0 and Lee II-III groups (P<0.05). The number of M2 macrophages in the S1, T1 and Lee IV-V groups was significantly higher in the tubulointerstitial group than in the S0, T0 and Lee II-III groups (all P<0.05). The blood urea nitrogen, serum creatinine and 24 h urine protein levels in the T1 and Lee IV-V groups were significantly higher than those in the T0 and Lee II-III groups, and the serum albumin levels in the Lee IV-V group were significantly lower (all P<0.05). Spearman correlation analysis showed that the number of DCs in renal interstitium was positively correlated with the proportion of tubulointerstitial fibrosis. There were a positive correlation between the proportion of glomerular segmental sclerosis and tubulointerstitial fibrosis and renal interstitial macrophages and M2 macrophages. The number of M2 macrophages was positively correlated with serum creatinine and 24 h urine protein (both P<0.05). Conclusions The number of DCs and M2 macrophages in kidneys are positively correlated with the clinicopathological features of IgAN patients, which indicates that they may be associated with disease progression. Key words: Glomerulonephritis, IgA; Dendritic cells; Macrophages; Biopsy; Fluoroimmunoassay