Role of the IL-6/STAT3 Signaling Axis in the Protective Effect of Selenomethionine Against Zearalenone-Induced Hepatic Inflammatory Injury in Rabbits

Abstract

Zearalenone (ZEA), a mycotoxin primarily generated by the Fusarium species, constitutes a prevalent contaminant in both human and animal feedstuffs. Chronic exposure to this mycotoxin induces hepatic inflammatory responses in livestock species including rabbits, ultimately leading to organ damage. Selenomethionine (SeMet), an organic selenium source recognized for its antioxidant properties and anti-inflammatory bioactivity, demonstrates protective benefits in animals through its detoxification mechanism and growth promotion. The present study investigated the protective effect of SeMet against ZEA-induced hepatic inflammation and elucidated its underlying mechanisms. Fifty healthy 90-day-old rabbits were randomly divided into five groups: control, ZEA-exposed and three SeMet-supplemented groups receiving 0.2, 0.35 or 0.5 mg/kg via dietary inclusion. After two weeks of SeMet pretreatment, ZEA administration (1.2 mg/kg B.W.) was imitated via oral gavage daily for one week in both the ZEA group and three SeMet-treated groups. As a result, ZEA exposure induced the significant structural disruption of the hepatic lobules, accompanied by increased collagen deposition, elevated pro-inflammatory cytokine profiles (IL-6, IL-1β, TNF-α) and reduced anti-inflammatory mediator levels (IL-10, TGF-β). SeMet supplementation alleviated ZEA-induced histological alterations, including inflammatory cell infiltration and collagen accumulation. Biochemical analysis indicated the restoration of inflammatory markers to near-normal levels when treated with SeMet. Notably, immunohistochemical results showed that SeMet significantly reduced the protein levels of IL-6 and its downstream target STAT3 under ZEA exposure. These findings indicated that SeMet attenuated ZEA-induced hepatic inflammation by modulating the IL-6/STAT3 signaling axis, with dietary supplementation of 0.35 mg/kg SeMet exhibiting the most significant effect on alleviating ZEA-induced hepatic inflammatory injury.

Keywords: IL-6/STAT3 signaling axis; hepatic injury; inflammatory cytokines; selenomethionine; zearalenone.

Figure 1

Effects of SeMet on liver tissue structure in rabbits exposed to ZEA. Representative graphs of liver sections stained with HE (20× magnification; scale bar = 50 μm): Black arrows, inflammatory cell infiltration (n = 5). Treatments represented as (A) control, (B) ZEA-challenged group, (C) SeMet-L group, (D) SeMet-M group and (E) SeMet-H group. Control group exhibited orderly arranged hepatocytes and hepatic sinusoids around central vein and intact structural integrity. ZEA-challenged group displayed disorganized hepatocyte alignment, dilated and congested sinusoids and inflammatory infiltration. Groups pretreated with different doses of SeMet showed notably ameliorated histoarchitectural damage, with most pronounced improvement (p < 0.05) in medium-dose group.

Figure 2

Hepatic fibrosis assessment in rabbit livers. (A) Sirius red staining results; (B) quantification of collagen fiber content. Sirius red staining revealed elevated collagen deposition in the ZEA-challenged group, predominantly localized to ductule or vascular walls. SeMet pretreatment reduced the accumulation of collagen, with the medium-dose group showing the most significant reduction (p < 0.001). Minimal collagen deposition was observed in the control group. Top row: 10× magnification, scale bar = 100 μm. Bottom row: Enlarged views (20×magnification) of boxed regions in the top row, scale bar = 50 μm (n = 5).

Figure 3

ELISA analysis results of hepatic inflammatory cytokine levels. (A–E): The contents of interleukin-10 (IL-10), transforming growth factor-β (TGF-β), interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in rabbit livers, respectively (n = 5).

Figure 4

mRNA expression levels of IL-6/STAT3 pathway-related genes in hepatic tissues. (A–E) The relative mRNA abundances of IL-6, STAT3, IL-10, IL-1β and TNF-α in rabbit livers (n = 5).

Figure 5

Immunohistochemistry analysis of IL-6 and STAT3 proteins in rabbit livers after ZEA exposure. (A) Representative photomicrograph showing IL-6 and STAT3 immunohistochemical staining. (B,C) Quantification of IL-6 and STAT3 protein-positive areas, respectively. Magnification: 10×; scale bar: 100 μm (n = 5).

Figure 6

The scheme outlining the experimental design for animal grouping and drug administration (n = 5).