A synbiotic consisting of Lactiplantibacillus plantarum S58 and β-glucan ameliorates exertional heat stroke-induced intestinal barrier injury via modulating the MAPK pathway and gut microbiota in rats

Abstract

Exertional heat stroke (EHS) is a severe and potentially life-threatening condition that primarily affects healthy individuals engaged in strenuous physical activity under hot and humid environments, representing an escalating public health challenge in the context of global climate change. This study evaluated the preventive potential of a synbiotic formulation containing Lactiplantibacillus plantarum S58 and β-glucan (S58/βG) in a rat model of EHS. Rats received S58/βG pretreatment for 14 or 28 days before EHS induction, and a range of indicators including core temperature, intestinal histopathology, tight junction protein expression, MAPK signaling pathway activation, epithelial apoptosis, and gut microbiota composition were systematically assessed. The results demonstrated that S58/βG effectively enhanced thermotolerance, maintained intestinal integrity, and mitigated systemic organ injury. Mechanistically, it inhibited the phosphorylation of p38 and ERK, attenuated epithelial apoptosis, and maintained the expression of ZO-1, occludin, and E-cadherin. Moreover, S58/βG modulated the gut microbiota by progressively increasing beneficial bacteria and reducing potentially pathogenic bacteria over time. These findings demonstrate, for the first time, that S58/βG confers protection against EHS by concurrently modulating the gut microbiota and MAPK pathway, highlighting its potential as a dietary intervention to prevent EHS in vulnerable populations.