Abstract

D-lactate is a metabolite originating from bacterial metabolism that accumulates as a result of dietary distur-bances in cattle, leading to ruminal acidosis. D-lactate exerts functions as a metabolic signal inducing metabolic reprogramming and extracellular trap (ET) release in polymorphonuclear leucocytes (PMNs). We previously demonstrated that D-lactate induces metabolic reprogramming via hypoxia-induced factor 1 alpha (HIF-1 alpha) stabilization in bovine fibroblast-like synoviocytes (FLSs). In the present study, the role of HIF-1 in ET formation induced by D-lactate was assessed. HIF-1 alpha stabilization in PMNs was controlled by mitochondrial reactive oxygen species (mtROS) release. Furthermore, inhibition of mitochondrial complex I and scavenging of mtROS decreased D-lactate-triggered ETosis. D-lactate-enhanced HIF-1 alpha accumulation was dependent on the PI3K/Akt pathway but independent of GSK-38 activity. Pharmacological blockade of the PI3K/Akt/HIF-1 and GSK-38 axes inhibited D -lactate-triggered ETosis and downregulated PDK1 and LDHA expression. However, only GSK-38 inhibition decreased the expression of glycogen metabolism enzymes and prevented the decline in glycogen stores induced by D-lactate exposure. The results of this study suggest that mtROS, PI3K/Akt/HIF-1 and GSK-38 axes regulate carbohydrate metabolism adaptations that support D-lactate-induced ET formation in cattle.