Modulating the gut microbiota and inflammation is involved in the effect of diosgenin against diabetic nephropathy in rat

Abstract

Background: Diabetic nephropathy (DN) is a severe complication of diabetes, which has been increasingly associated with gut microbiota dysbiosis and inflammatory dysregulation.

Objective: This study investigates the dual therapeutic potential of diosgenin (DIO), a steroidal sapogenin, in modulating the gut-kidney axis and NLRP3 inflammasome activity in a streptozotocin (STZ)-induced DN rat model.

Methods: Oral DIO administration (20 mg/kg, 8 weeks) was used to treat the DN rats. The study assessed the effects on metabolic and renal function parameters, renal apoptosis and fibrosis, gut microbiota diversity, and NLRP3 inflammasome activation in the kidney.

Results: DIO treatment ameliorated the progression of DN, improving metabolic and renal function. It attenuated renal apoptosis and fibrosis and restored gut microbiota diversity, particularly enriching the abundance of Lachnospiraceae and Eubacterium. Mechanistically, DIO suppressed NLRP3 inflammasome activation in the kidney, disrupted the LPS-TLR4/NF-κB signaling cascade, and reduced systemic pro-inflammatory cytokines (IL-1β, IL-6).

Conclusion: DIO is a multitarget agent that addresses both gut microbiota homeostasis and NLRP3-driven inflammation, presenting a novel therapeutic strategy for DN through modulation of the gut-kidney axis.

Keywords: NLRP3 inflammasome; anti-inflammatory; diabetic nephropathy; diosgenin; gut microbiota.

FIGURE 1

DIO ameliorated glucose metabolism and kidney injury in DN rats after 8 weeks of administration. (A) The structure of diosgenin (DIO). (B) Serum glucose, (C) Urine microalbumin. (D) Serum creatinine. (E) Urine urea nitrogen, (F) The renal index. (G) H&E staining, (H) PAS staining and (I) Masson staining of representative kidney sections, photographed at ×200 magnification. ^* P < 0.05, ^** P < 0.01, ^*** P < 0.001, compared with DN group.

FIGURE 2

DIO blocked STZ-induced cell apoptosis of kidney in DN rats. (A) The kidney sections were stained with TUNEL and measured by confocal microscope. The apoptotic cells showed green fluorescence (200×). (B) The statistics of TUNEL-positive cells (%). ^* P < 0.05, ^** P < 0.01, ^*** P < 0.001, compared with DN group.

FIGURE 3

DIO attenuated renal fibrosis in DN. (A) Representative immunohistochemical staining of fibronectin and collagen IV in renal tissues in mouse model. (B) Renal expression of fibrosis markers including fibronectin, collagenin IV, vimentin, and α-SMA in DN rats. Densitometric analysis of (C) fibronectin, (D) collagenin IV, (E) vimentin, and (F) α-SMA. ^* P < 0.05, ^** P < 0.01, ^*** P < 0.001, compared with DN group.

FIGURE 4

DIO suppressed renal inflammation. (A) Immunohistochemical staining of IL-1β, IL-6 and TNF-α in renal tissues. (B) Western blot analysis of NLRP3, Cleaved caspase-1 and IL-1β. The ratio of Western blot analysis of (C) NLRP3, (D) Cleaved caspase-1, (E) IL-1β. ^* P < 0.05, ^** P < 0.01, ^*** P < 0.001, compared with DN group.

FIGURE 5

DIO suppressed colon inflammation and improved gut barrier. Representative photomicrographs of HE-stained small intestine sections and photomicrographs of immunofluorescence for Claudlin-1 and ZO-1 at ×200 magnification.

FIGURE 6

DIO altered gut microbiota in DN rats. (A) ACE index. (B) Chao1 index. (C) Shannon index curve. (D) Rank abundance curve. (E–G) Weighted UniFrac PCoA (Principal coordinates analysis). (H) Relative abundance at phylum level. (I) Relative abundance at genus level. (J) Relative abundance of the significantly-altered bacteria at the genus level. Data are represented as means ± SD (n = 5). ^* P < 0.05, ^** P < 0.01 and ^*** P < 0.001 indicated significant difference between compared groups.