Curcumin ameliorates the pathogenesis of IgA nephropathy by regulating intestinal mucosal immunity through inhibition of Toll-like receptor 9/myeloid differentiation factor 88/nuclear factor kappa B signaling pathway
10.3760/cma.j.cn441217-20241122-01148
- VernacularTitle:姜黄素通过抑制Toll样受体9/髓分化因子88/核因子κB信号通路调节肠黏膜免疫改善IgA肾病
- Author:
Ziyang YE
1
;
Qi DUAN
;
Feng WU
;
Xiaotong LI
;
Sijie ZHANG
;
Yafeng LI
Author Information
1. 山西中医药大学第三临床学院，晋中 030619
- Publication Type:Journal Article
- Keywords:
Curcumin;
Glomerulonephritis, IgA;
Caco-2 cells;
Toll-like receptors;
Mucosal immunity
- From:
Chinese Journal of Nephrology
2025;41(5):358-371
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the role of curcumin (Cur) in improving IgA nephropathy (IgAN) and its related mechanisms.Methods:Fifty 7-month-old miR-23b knockout (miR-23b -/-) mice weighing (25±5) g were used to establish an IgAN disease model, and were randomly divided into IgAN group, IgAN+Cur (150 mg/kg) group and IgAN+Cur (300 mg/kg) group using simple randomisation. Sixteen healthy 7-month-old weighing (25±3) g C57BL/6J wild-type mice served as the normal control group. IgAN+Cur (150 mg/kg) and IgAN+Cur (300 mg/kg) groups were respectively gavaged continuously with 150 mg/kg Cur and 300 mg/kg Cur for 8 weeks, and the normal control and IgAN groups were gavaged continuously with an equal dose of 0.9% sodium chloride solution for 8 weeks. The samples of urine, serum, intestinal fluid, intestinal tissues, kidney tissues and liver tissues were collected from each group. In vitro experiments, human cloned colon adenocarcinoma (Caco-2) cells were divided into blank control (Ctrl), Ctrl+Cur (10 μmol/L), Ctrl+ Cur (60 μmol/L), tumor necrosis factor-α（TNF-α), TNF-α+Cur (10 μmol/L) and TNF-α+Cur (60 μmol/L) groups. Enzyme-linked immunosorbent assay was used to detect serum alanine transaminase, aspartate transaminase, secretory IgA (sIgA), creatinine, blood urea nitrogen, 24 h urine microalbumin, as well as sIgA, TNF-α, interleukin（IL)-6 and IL-1β in the intestinal fluids. HE staining was used to observe the effect of Cur on liver tissues, the hyperplasia of glomerular mesangial zone in kidney tissues and the morphological and structural changes of intestinal epithelial barrier, and the histopathological damage scores were performed respectively. PAS staining was used to observe the changes of glomerular basement membrane and mesangial matrix. Immunofluorescence was used to observe the deposition of immune complexes in the glomerular mesangial zone. Real-time quantitative PCR was used to detect the mRNA expression levels of B-cell activating factor ( BAFF) and a proliferation inducing ligand ( APRIL). Western blotting was used to detect the protein expression levels of tight junction proteins zonula occluden-1 (ZO-1) and occludin in the mouse intestinal tissues. The potential targets of Cur in IgAN were predicted. Western blotting was used to detect the protein expression levels of tight junction proteins, as well as Toll-like receptor 9 (TLR9), myeloid differentiation primary response protein (MyD88), nuclear factor-κB p65 (NF-κB p65) and p-NF-κB p65. Results:Genetic identification results revealed that all IgAN model mice exhibited the miR-23b -/- genotype, confirming successful model establishment. Seven-month-old mice were subsequently selected for Cur treatment. Histopathological analysis demonstrated no significant differences in hepatic tissue morphology across groups, with comparable liver histopathological injury scores and unaltered liver function parameters, thereby validating the safety of Cur administration. Compared with the normal control group, IgAN mice displayed elevated levels of serum sIgA, serum creatinine, blood urea nitrogen and 24 h urine microalbumin (all P<0.05). Renal pathological results revealed severe mesangial hypercellularity in glomeruli, higher glomerular injury scores, and notable glomerular mesangial deposits of IgA, IgG and complement C3 in IgAN mice (all P<0.05). Additionally, intestinal pathological alterations were observed, including structural changes in intestinal epithelium and Peyer's patches, accompanied by significantly higher intestinal histopathological injury scores in IgAN mice ( P<0.05). Intestinal epithelial expression levels of ZO-1 and occludin were significantly reduced, while sIgA, TNF-α, IL-1β and IL-6 in intestinal fluid were elevated (all P<0.05). Serum FITC fluorescence intensity was markedly increased, and intestinal tissue exhibited upregulated mRNA expression of BAFF and APRIL (all P<0.05). Following Cur treatment, serum sIgA level and renal function indices in mice showed partial recovery (all P<0.05). Renal pathological improvements included alleviated mesangial hypercellularity, reduced glomerular injury scores, and diminished glomerular immune complex deposition (all P<0.05). Intestinal pathologies, including epithelial and Peyer's patch lesions, were mitigated, with decreased intestinal histopathological injury scores ( P<0.05). Additionally, intestinal tight junction protein expression levels were upregulated, intestinal fluid sIgA level was reduced, inflammatory markers were attenuated, serum FITC fluorescence intensity was declined, and intestinal BAFF and APRIL mRNA expression levels were downregulated (all P<0.05). In vitro experiments demonstrated that TNF-α exposure reduced tight junction protein expression in Caco-2 cells, whereas Cur treatment reversed the effect (all P<0.05). Target prediction analysis revealed that Cur effectively bound to TLR9 structural domain in IgAN. Experimental validation confirmed that Cur treatment suppressed the upregulated protein expression levels of TLR9, MyD88, NF-κB p65 and p-NF-κB p65 in intestinal tissues of IgAN mice (all P<0.05). Conclusion:Cur has a significant effect in the treatment of IgAN and can regulate intestinal mucosal immunity by inhibiting the TLR9/MyD88/NF-κB signaling pathway, thereby reducing renal injury and protecting the kidneys.
