EFFECT OF LACTATE IN A MURINE MODEL OF COLITIS

IRAPORDA, C; ROMANIN, D; CAYET, D; SIRARD, JC; GARROTE, G; ABRAHAM, AG; RUMBO, M

San Miguel de Tucumán

Simposio; IV Simposio Internacional de Bacterias Lácticas; 2015

CERELA CONICET

We have previously shown that the non bacterial fraction of kefir milk can modulateinflammatory activation of intestinal epithelial cells and that lactate present in thisfraction may be the principal component responsible of this property. In order to linkthe in vitro capacity of lactate to the in vivo effect, we evaluated the potential toprotect mice from TNBS‐induced colitis. 22‐25g 6‐weeks old Balb/c mice wereemployed. Lactate 200 mM was administered either orally or by intrarectal instillation(200 μl); control groups received water intake or an instillation of PBS. Experimentalcolitis was induced 5 days after oral intake or 2 h after instillations, by intrarectaladministration of 0.5 mg of TNBS in 50% ethanol or 50% ethanol as control. Animalswere sacrificed after 48h. With the aim of study the possible mechanism involved inthe immunomodulatory activity the in vitro Caco‐2 ccl20:luc cell reporter system wasused. We evaluated the effect of preincubation of cells with different concentration oflactate and glycolysis inhibitors (such as 2‐deoxyglucose, 3 bromo‐priruvate or sodiumoxamate) and analyzed the glucose intake, lactate production and luciferase activityinduced by flagelin (Flic). In the in vivo TNBS‐induced colitis model, no significantvariation in weight and no signs of inflammation were observed in vehicle groups.Characteristic features of colitis, colonic inflammation with several epithelial damagewere observed in PBS‐treated group, leading to an inflammation score of 4.67 ±2.34,and higher concentration of serum IL‐6 after 24 h (p<0.05). No signs of protectionwere observed in mice that received lactate orally. In contrast, group pre‐treatedintrarectaly with lactate showed lower colonic inflammation with lower levels ofserum IL‐6 (p<0.05). It is known that cells involved in immune response mayexperiment a metabolic reprogramming in order to produce the appropriate effect.Although stimulation of Caco‐2 ccl20:luc cells with Flic did not produce a significantincrease in glucose intake and lactate production, the treatment with lactate orglycolysis inhibitors impaired CCL20 production induced by Flic in a dose‐responsemanner, indicating that the glycolytic pathway is involved in epithelial cell response. Inconclusion, increase in lactate concentration in colon could be involved inperturbation of metabolic reprogramming of intestinal epithelial cells and resultsprotective for TNBS‐induced colitis.