Sodium Humate Combined with Low-Dose Cefixime Alleviates Intestinal Injury in ETEC Infection via Inhibition of the TLR4/NF-κB Pathway

This study aimed to evaluate the protective effects of sodium humate (HNa) alone and in combination with low-dose cefixime (CFM) in mice infected with enterotoxigenic Escherichia coli (ETEC). An ETEC infection mouse model was established to compare the effects of individual or combined interventions on physiological parameters, intestinal morphology, barrier function, levels of specific intestinal bacterial groups, cell proliferation/apoptosis, and inflammatory pathways. The results showed that the HNa + CFM combination significantly promoted body weight recovery, ameliorated damage to jejunal villus structure and ultrastructure, and increased the mRNA expression of mucins (MUC1/2/3) and tight junction proteins (ZO-1, Occludin, Claudin-1) compared to the ETEC group. Concurrently, the combined treatment significantly reduced fecal E. coli counts and increased the abundance of Lactobacillus and Bifidobacterium, promoted epithelial repair by upregulating proliferation-related genes (EGFR, PCNA, TGF-β1), and decreased the Bax/Bcl-2 ratio. Furthermore, the combined intervention significantly reduced serum LPS levels and consequently suppressed ETEC-induced activation of the TLR4/MyD88/NF-κB pathway, as evidenced by reduced protein expression of TLR4 and MyD88, decreased phosphorylation of IκBα and p65, and diminished nuclear accumulation of NF-κB p65, leading to downregulation of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and elevation of IL-10. In conclusion, the combined application of HNa and low-dose CFM showed additional protective benefits against ETEC infection. These effects were associated with multi-targeted repair of the intestinal barrier, modulation of measured bacterial levels, and suppression of excessive inflammatory responses. This strategy offers a potential approach for the clinical management of bacterial enteritis and reducing antibiotic dependence.