Expression and significance of Toll-like receptor 4 in renal tissue and peripheral blood of children with idiopathic nephrotic syndrome

Abstract

Objective To investigate the expression and significance of Toll-like receptor 4 (TLR4) in renal tissue and peripheral blood of children with idiopathic nephrotic syndrome(INS). Methods The renal biopsy tissues of 78 children with INS diagnosed in the First Affiliated Hospital of Xinxiang Medical University from October 2015 to June 2018 and normal renal tissues of 21 children (control group 1) were collected, and the expressions of TLR4 in the renal tissue was detected by using immunohistochemical method.The expression of TLR4 in different renal pathological types and clinical types of INS was compared, and the correlation of TLR4 with 24-hour urinary protein and serum albumin was analyzed.The expression levels of TLR4 in peripheral blood of children with INS before and after treatment (active stage and remission stage) and 23 healthy children (control group 2) were detected by enzyme linked immunosorbent assay(ELISA). The serum expression levels of TLR4 in different renal pathological types and clinical types of INS were compared, and the correlation of TLR4 with 24-hour urinary protein and serum albumin was analyzed; The correlation between TLR4 expression in renal tubules and in the serum of children with INS was also analyzed. Results (1)Compared with the expression of TLR4 in normal renal tissues[(0.93±0.26)%], the expression of TLR4 in glomeruli and interstitium of all pathological types of INS [mesangial proliferative glomerulonephritis (MsPGN): (0.93 ± 0.21)%, focal segmental glomerulosclerosis (FSGS): (1.02±0.25)%, membranous glomerulonephritis(MN): (1.03±0.09)%, minimal change disease(MCD): (1.02±0.27)%]was not significantly different (F=0.741, P=0.562), but the expression of TLR4 in renal tubules[MCD: (82.94±4.62)%, MN: (63.54±1.98)%, MsPGN(42.32±2.97)%, FSGS: (22.60±2.07)%] was significantly increased (F=1 929.842, P<0.01), Especially, the expression of TLR4 in renal tubules of MCD type INS was significantly higher than that of MN, MsPG N and FSGS [MCD: (82.94±4.62)%, MN: (63.54±1.98)%, MsPGN: (42.32±2.97)%, FSGS: (22.60±2.07)%], and the differences were statistically significant(all P<0.01). TLR4 expression in renal tubules was the highest in steroid-sensitive nephrotic syndrome (SSNS) type and the lowest in INS patients with steroid-resistant nephrotic syndrome (SRNS) type, and the differences were statistically significant(F=220.951, P<0.01). (2)The expression of serum TLR4 in INS children at the active stage [MsPNG: (143.36±12.99) ng/L, FSGS(75.94±7.29) ng/L, MN(210.22±14.66) ng/L, MCD(283.93±21.58) ng/L]was significantly higher than that in INS children at remission stage [MsPNG: (29.51±4.93) ng/L, FSGS(15.66±3.78) ng/L, MN(45.40±5.73) ng/L, MCD(62.29±7.90) ng/L]and control group 2[(0.69 ± 0.33) ng/L], and the differences were statistically significant(all P<0.01); the expression of serum TLR4 in INS children at remission stage was significantly higher than that in the control group 2 (F=286.287, P<0.01). TLR4 had the highest expression level in serum of MCD type INS children at active and remission stages, followed by MN and FSGS successively.The expression of serum TLR4 was highest in SSNS and lowest in SRNS, and the differences were statistically significant (F=147.438, P<0.01). (3)The expression of TLR4 in renal tubules of children with INS[(62.82 ±20.94)%]was positively correlated with the expression of TLR4 in serum[(213.26±73.33) ng/L] (r=0.852, P< 0.05). The expression levels of TLR4 in renal tubules and serum of INS patients at active stage were positively correlated with 24-hour urinary protein level[(123.05±33.55) mg/kg] (r=0.401, 0.427, all P<0.05), and negatively correlated with serum albumin level[(19.54±3.55)g/L] (r=-0.602, -0.617, all P<0.05). Conclusions The expression of TLR4 in renal tubules and serum of children with INS increases, and may be related to different renal pathological types and clinical types of children with INS, as well as disease activity. Key words: Toll-like receptor 4; Kidney tissue; Serum; Idiopathic nephrotic syndrome; Child