Characterizing NLRP11 Activation by Mycobacteria to Enhance Innate Immune Responses

About This Grant

The NLRP11 protein is only expressed in primates and participates in the activation of the canonical NLRP3 and non-canonical caspase-4 inflammasome activation after infection with gram-negative bacteria. We found that the atypical gram-positive pathogen Mycobacterium tuberculosis (Mtb) and the opportunistic pathogen M. kansasii both activate the non-canonical NLRP11 inflammasome in a caspase-4/5-dependent pathway. In specific aim 1.1 we propose to screen a collection of mycobacterial species, including Mtb strains of the major documented lineages, to characterize which ones are being recognized by the NLRP11/caspase-4 inflammasome. In specific aim 1.2 we will screen subcellular fractions of Mtb to identify which one contains the ligand(s) being detected by NLRP11 and/or caspase-4. Finally, in specific aim 2 we propose a genetic gain-of-function screen to discover the genes in Mtb that encode for the putative ligand(s). The discovery of a novel ligand originating from the atypical gram-positive Mtb will of great significance for structure-function analysis of the NLRP11/caspase-4 inflammasome. Also, the knowledge could potentially be exploited to overexpress the ligand in the current tuberculosis vaccine strain to improve its immunogenicity.