Proper function of the intestinal barrier plays a crucial role to maintain normal health by selectively absorbing nutrients and keeping out pathogens. Increased gut permeability is a feature of several diseases, including metabolic syndrome, but whether it is a cause or a consequence is unknown. We therefore examined the impact on intestinal barrier function of streptozotocin (STZ) -induced diabetes in C57BL/6J mice that were fed either standard chow or high-fat high-sucrose (HFHS) diet for 13wk. Moderate hyperglycemia was induced by low-dose i.p. STZ injection and 12wk later, intestinal tissues were collected and processed for quantification of colonic mucin and tight junction proteins. In both HFHS- and chow-fed mice, STZ treatment resulted in significantly elevated blood glucose levels compared to vehicle-treated controls (HFHS blood glucose 249.1 mg/dL vs. 157.5 mg/dL, p=0.0008; chow 330.2 mg/dL vs. 139.7mg/dL, p=0.0005) . In HFHS-fed mice, STZ hyperglycemia was associated with reductions of both the colonic mucin layer, as measured by Alcian Blue (AB) staining (percent area 52.6 vs. 62.4, p<0.0001) , and the tight junction protein E-cadherin (percent area 34.7 vs. 55.9, p=0.0029) . In non-obese chow-fed mice, however, STZ-induced hyperglycemia had no significant impact on AB mucin staining or E-cadherin protein abundance. Similarly, levels of colonic mucins and E-cadherin were inversely correlated with blood glucose levels in HFHS-fed mice (AB R2=0.43, p=0.0116; E-cadherin R2=0.30, p=0.0439) , but not in chow-fed mice. We conclude that while the combination of hyperglycemia and diet-induced-obesity is sufficient to impair intestinal barrier function, neither obesity nor diabetes in isolation is sufficient to induce this effect. Our additional finding that the magnitude of colonic dysfunction is correlated with the degree of hyperglycemia implicates excess glucose as a potential driver of obesity-associated impairment of intestinal barrier function.
K.L.Francis: None. K.M.Alonge: None. S.J.W.Hu: None. B.N.Phan: None. T.P.Doan: None. C.A.Krutzsch: None. Z.Maat: None. J.M.Scarlett: None. M.W.Schwartz: None.
National Institutes of Health T32 DK007742