Lactate Stimulates IL-4 and IL-13 Production in Activated HuT-78 T Lymphocytes Through a Process That Involves Monocarboxylate Transporters and Protein Hyperacetylation.

Mucosal cells of the gastrointestinal and female reproductive tract are constantly exposed to l- and d-lactate of bacterial origin. These compounds not only protect the host from pathogen colonization but also modulate the activity of mucosal immune cells, thereby playing an important role in inflammatory host responses. In this study, we demonstrated that exposure of anti-CD3/CD28 or phorbol 12-myristate 13-acetate (PMA)/ionomycin-activated HuT-78 T lymphocyte cells to 10-20 mM d-lactate significantly increased IL-4 and IL-13 production. Interestingly, the d-lactate isomer, exclusively produced locally by gut or cervicovaginal microbiota, was found to be more potent than the l-isomer. Interestingly, neither of the strong histone deacetylase inhibitors [structurally similar butyrate and suberoylanilide hydroxamic acid (SAHA)] was as effective in the stimulation of IL-13 production as d-lactate. Lactate transport through monocarboxylate transporters was required for lactate-enhanced IL-13 production in a manner that was not hydroxycarboxylic acid receptor 1-dependent. Furthermore, lactate treatment increased the acetylation of GATA-3, a critical regulator of Th1/Th2 differentiation and resulted in H3 and H4 histone hyperacetylation state, which is a characteristic feature of transcriptionally active chromatin. Both lactate isomers also enhanced IL4 and IL13 promoter-driven activity of reporter constructs in murine and human cells. Together, these findings demonstrate that a local millimolar concentration of l- or d-lactate may play an important role in the modulation of inflammation-mediated processes.