Heat stress (HS) can be detrimental to the gut health of swine. Many negative outcomes induced by HS are increasingly recognized as including modulation of intestinal microbiota. In turn, the intestinal microbiota is a unique ecosystem playing a critical role in mediating the host stress response. Therefore, we aimed to characterize gut microbiota of pigs' exposure to short-term HS, to explore a possible link between the intestinal microbiota and HS-related changes, including serum
cytokines, oxidation status, and intestinal epithelial barrier function. Our findings showed that HS led to intestinal morphological and integrity changes (villus height, serum
diamine oxidase [DAO], serum D-
lactate and the relative expressions of
tight junction proteins), reduction of serum
cytokines (
interleukin [IL]-8,
IL-12,
interferon-gamma [IFN-γ]), and
antioxidant activity (higher
glutathione [GSH] and
malondialdehyde [MDA] content, and lower
superoxide dismutase [SOD]). Also,
16S rRNA sequencing analysis revealed that although there was no difference in microbial α-diversity, some HS-associated composition differences were revealed in the ileum and cecum, which partly led to an imbalance in the production of
short-chain fatty acids including
propionate acid and
valerate acid. Relevance networks revealed that HS-derived changes in bacterial genera and microbial metabolites, such as Chlamydia, Lactobacillus, Succinivibrio, Bifidobacterium, Lachnoclostridium, and
propionic acid, were correlated with oxidative stress, intestinal barrier dysfunction, and
inflammation in pigs. Collectively, our observations suggest that intestinal damage induced by HS is probably partly related to the gut microbiota
dysbiosis, though the underlying mechanism remains to be fully elucidated.