A Novel Approach to Restore Epithelial Barrier Homeostasis to Treat Inflammatory Bowel Disease

SUMMARY Intestinal barrier function is compromised in enteric and systemic diseasesincluding infectious enterocolitisfood allergyceliac diseasegraft versus host diseaseGvHDand inflammatory bowel diseaseIBDThe co founders of Thelium Therapeutics discovered the central role of myosin light chain kinaseMLCKin barrier regulation and demonstrated that targeted intestinal epithelial MLCK inhibition limits experimental IBD and GvHDUnfortunatelysevere toxicities associated with barrier independent MLCK functions in epithelia and other tissuese gsmooth musclepreclude therapeutic targeting of MLCK enzymatic activityWe recently reportedGraham et alNature Medicinethat a specific MLCK splice variantMLCKis central to barrier regulation and depends on interactions mediated by immunoglobulin cell adhesion molecule domainIgCAMWe solved the IgCAMcrystal structureidentified a drug binding pocket unique to IgCAMand screened a library ofdrug like moleculesOne compoundDivertinbound IgCAMprevented cytokine induced MLCKrecruitmentmyosin II regulatory light chain phosphorylationand barrier dysfunctionCriticallyDivertin did not inhibit MLCK enzymatic functionepithelial wound healingor smooth muscle contractionand in vivo toxicity studies failed to identify adverse effectsDivertin prevented acute TNF induced barrier loss in vivomiceand ex vivohuman intestinal biopsiesand restored immune mediated barrier loss in vivoILknockout miceFinallyDivertin delayed onset and prevented progression of experimental immune mediatedT cell transferIBDas indicated by barrier preservation and restorationreduced mucosal immune activationand enhanced survivalAlthough useful as a tool compoundDivertin lacks characteristics required for a lead compoundThis proposal will overcome that obstacle to clinical application of Divertin by discovering lead compounds with similar activitiesCutting edgephysics based rational design and molecular dynamic simulation methods has already been used to probe an expansive compound library and identify those with predicted high affinity binding to the MLCKIgCAMcrystal structureThose molecules will be subjected to a rank order screening funnel to identify compounds with suitable MLCKbinding affinitiesefficacy in preserving and restoring epithelial barrier functionand absence of enzymatic inhibitory activityThese lead compounds will be suitable for optimization and development to facilitate IND enabling studies for a first in class barrier restorative therapy to manage gastrointestinal and systemic diseases PROJECT NARRATIVE The epithelial cells that line the inside of the intestines form a barrierAlthough this barrier must be selectively permeable in order to allow absorption of nutrients and water as well as secretion of waste productsexcessive permeability has been implicated as an early step in development of intestinal and systemic diseasesThe proposed studies will advance lead discovery efforts towards a first in class therapeutic thatby repairing the intestinal barrierwill serve as both a preventative agent and a treatment for active disease