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Background Intestinal inflammation disrupts the microbiota composition leading to an expansion of Enterobacteriaceae family members (dysbiosis). Associated with this shift in microbiota composition is a profound change in the metabolic landscape of the intestine. It is unclear how changes in metabolite availability during gut inflammation impact microbial and host physiology. Results We investigated microbial and host lactate metabolism in murine models of infectious and non-infectious colitis. During inflammation-associated dysbiosis, lactate levels in the gut lumen increased. The disease-associated spike in lactate availability was significantly reduced in mice lacking the lactate dehydrogenase A subunit in intestinal epithelial cells. Commensal E. coli and pathogenic Salmonella, representative Enterobacteriaceae family members, utilized lactate via the respiratory L-lactate dehydrogenase LldD to increase fitness. Furthermore, mice lacking the lactate dehydrogenase A subunit in intestinal epithelial cells exhibited lower levels of inflammation in a model of non-infectious colitis. Conclusions The release of lactate by intestinal epithelial cells during gut inflammation impacts the metabolism of gut-associated microbial communities. These findings suggest that during intestinal inflammation and dysbiosis, changes in metabolite availability can perpetuate colitis-associated disturbances of microbiota composition.

A mutation associated with nearly 1/3 of human diffuse large B cell lymphomas (DLBCLs) has been identified within MyD88. This mutation correlates with tumor cell proliferation and survival involving spontaneous and sustained activation of NF-κB signaling. MyD88 is a central signaling adapter for the Interleukin-1 (IL-1R) and Toll-like receptors (TLRs). In normal healthy cells, MyD88 is thought to be held in an auto-inhibitory state with its own death and TIR domains fused together in negative self-regulation until activated by appropriate receptor mediated ligand engagement. Observation CADD derived small molecule compounds inhibit MyD88 dimer formation and protect against Staphylococcal enterotoxin B (SEB) induced death in animal models. Hypothesis Based on this observation we hypothesize that MyD88 specific small molecule inhibitors may be useful in treating DLBCLs bearing MyD88L265P. Approach Using in vitro and in vivo studies we characterize MyD88 specific SMIs for the ability to inhibit tumor cell proliferation and signaling in cancer cells bearing the oncogenic mutation MyD88L265P. Results 1) MyD88 SMIs are able to inhibit cell proliferation of DLBCLs bearing the MyD88L265P as measured by MTS cell proliferation assay, 2) recombinant MyD88 and SMIs exhibit unique binding chromatograms in comparison to DMSO controls as measured by thermal shift assay and 3) MyD88 SMIs are partially able to inhibit LPS activated TLR4 cell NF-kB signaling in comparison to the TLR4 specific inhibitor TAK242. Future studies defining the molecular mechanism of this mutation with additional human patient tumor isolates will inform and propel development of novel therapeutics to counteract both inflammation as well as tumor formation.

A recurring single amino acid somatic mutation associated with human diffuse large B cell lymphomas (DLBCLs), correlates with tumor cell proliferation and survival involving spontaneous and sustained activation of MyD88-dependent NF-κB and Janus Kinase (JAK) signaling pathways. MyD88 acts as a central signaling adapter for mediating innate and cytokine driven inflammation for the Interleukin-1 (IL-1R) and Toll-like receptors (TLRs). Computer aided molecular modeling of MyD88 and in silico screening have identified and functionally characterized MyD88 specific small molecule compounds shown to protect against Staphylococcal enterotoxin B (SEB) induced death in animal models. We hypothesize that MyD88 specific small molecule compounds may also be useful in treating DLBCLs bearing the oncogenic mutation MYD88L265P. Using in vitro and in vivo studies we evaluate MyD88 specific small molecule compounds for the ability to inhibit tumor cell proliferation and signaling in human patient cancer cells OCI Ly3 bearing the oncogenic mutation MYD88 L265P and OCI Ly19 DLBCLs. Previously we identified differences in the ability of MyD88 small molecule compounds to inhibit cell proliferation in activated human B cell lymphoma cells bearing the MyD88 L265P mutation. We now correlate these differences with a reduction of MyD88 interaction with IRAK in small molecule treated OCI-Ly3 cells bearing the MYD88 L265P mutation in comparison to OCI-Ly19 (wt-MyD88) and treated controls, as measured by CoIP. We continue to characterize MyD88 specific small molecule compounds that target MyD88 dimerization for their ability to reduce MyD88 containing signaling complexes in DLBCLs bearing MYD88 L265P mutation.