Expression of heat shock proteins 27 and 72 correlates with specific commensal microbes in different regions of porcine gastrointestinal tract

Abstract

The gastrointestinal (GI) tract of mammals is inhabited by trillions of microorganisms, resulting in exceedingly complex networking. The interaction between distinct bacterial species and the host immune system is essential in maintaining homeostasis in the gut ecosystem. For instance, the gut commensal microbiota dictates intestinal mucosa maturation and its abundant immune components, such as cytoprotective heat shock proteins (HSP). Here we examined physiological expression of HSP in the normal porcine GI tract and found it to be gut region- and cell type-specific in response to dietary components, microbes, and microbial metabolites to which the mucosa surface is exposed. Correlations between HSP72 expression and ileal Lactobacillus spp. and colonic clostridia species, and between HSP27 expression and uronic acid ingestion, were important interplays identified here. Thus this study provides novel insights into host-microbe interactions shaping the immune system that are modifiable by dietary regime.

Gut epithelial inducible heat-shock proteins and their modulation by diet and the microbiota

“…35,38,58,65 Thus, strong immunostaining of iHSP proteins is observed in villi of the small intestine and in upper-crypt epithelial cells in the colon, with virtually no staining along the crypts at either site. Of note, ileal Peyer's patches stained strongly for iHSPs in the pig, but the precise identity of the iHSP-containing cells was not disclosed.…”

“…70 Further links between the gut commensal microbiota and iHSPs in vivo were recently demonstrated in growing pigs. 65 Ileal HSP27 was found to correlate negatively with particular luminal bacteria (Lactobacillus reuteri and Enterobacteriaceae) ( Table 4). 65 Ileal iHSP correlated positively with lactic acid-producing bacteria and L. johnsonii.…”

“…58 A higher relative concentration of iHSP proteins was recorded in the distal ileum than in the proximal colon in growing pigs, suggesting higher microbial stimulation in the former in this species. 65 Data from humans are scant. One study reported immune detection of iHSP70 in the small intestine and the colon.…”

“…Of note, ileal Peyer's patches stained strongly for iHSPs in the pig, but the precise identity of the iHSP-containing cells was not disclosed. 65 In summary, iHSPs are expressed and are located in GECs in close contact with the lumen, and their tissue concentration essentially reflects the influence of the gut microbiota. Data on the expression of mHSPs and eHSPs in GECs are lacking.…”

“…35 Butyrate-induced expression of iHSP was protective against oxidant stress. 35 Importantly, Liu et al 65 observed in growing pigs that colonic iHSP was negatively correlated with propionic acid concentration and positively correlated with the percentage of isobutyrate in digesta. Surprisingly, however, they did not find correlations between iHSP and n-butyrate concentrations in this study.…”