Host gene-encoded severe lung TB: from genes to potential pathways

We are reporting that the two-locus genotype -2518 MCP-1 GG -1607 MMP-1 2G/2G promotes the expression of hyper-inflammation in response to M. tuberculosis infection, inducing extensive tissue damage and severe TB disease. Carriers of this two-locus genotype have a 13-fold higher chance of developing severe disease and 6.5-fold higher chance of developing permanent lesions, and a 3.864-fold higher chance of delayed response to first-line standardized treatment than carriers of any other relevant combination of genotypes at those two loci. Thus, these persons have an increased likelihood of poor health-related quality of life and of transmitting M. tuberculosis to other members of the community. In addition, through the analysis of human lung tissues, serum/plasma, and in vitro experiments, including in vitro infections of THP-1 cells with M. tuberculosis and micro-array analysis, we determined that this hyper-inflammation state is potentially driven by the MCP-1/MMP-1/PAR-1 pathway. Hence, we are providing markers for the identification of TB cases that may develop severe pulmonary disease and delayed response to treatment, and are providing the basis for development of novel host-targeted clinical interventions to ameliorate the severity of pulmonary TB.