Mouse Anti-M. tuberculosis 38kDa Monoclonal antibody, clone CHO/2300/4986

Mycobacterium tuberculosis (M. tuberculosis) has coevolved with humans for millennia and developed multiple mechanisms to evade host immunity. Restoring host immunity in order to improve outcomes and potentially shorten existing therapy will require identification of the full complement by which host immunity is inhibited. Perturbation of host DNA methylation is a mechanism induced by chronic infections such as HIV, HPV, lymphocytic choriomeningitis virus (LCMV), and schistosomiasis to evade host immunity. Here, we evaluated the DNA methylation status of patients with tuberculosis (TB) and their asymptomatic household contacts and found that the patients with TB have DNA hypermethylation of the IL-2/STAT5, TNF/NF-kappa B, and IFN-gamma signaling pathways. We performed methylation-sensitive restriction enzyme-quantitative PCR (MSRE-qPCR) and observed that multiple genes of the IL-12/IFN-gamma signaling pathway (IL12B, IL12RB2, TYK2, IFNGR1, JAK1, and JAK2) were hypermethylated in patients with TB. The DNA hypermethylation of these pathways was associated with decreased immune responsiveness with decreased mitogen-induced upregulation of IFN-gamma, TNF, IL-6, CXCL9, CXCL10, and IL-1 beta production. The DNA hypermethylation of the IL-12/IFN-gamma pathway was associated with decreased IFN-gamma-induced gene expression and decreased IL-12-inducible upregulation of IFN-gamma. This study demonstrates that immune cells from patients with TB are characterized by DNA hypermethylation of genes critical to mycobacterial immunity resulting in decreased mycobacteria-specific and nonspecific immune responsiveness.

SerB2 is an essential phosphoserine phosphatase (PSP) that has been shown to be involved in Mycobacterium tuberculosis (Mtb) immune evasion mechanisms, and a drug target for the development of new antitubercular agents. A highly similar (91.0%) orthologous enzyme exists in the surrogate organism Mycobacterium marinum (Mma) and could have acquired similar properties. By homology modeling, we show that the two PSPs are expected to exhibit almost identical architectures. MmaSerB2 folds into a homodimer formed by two intertwined subunits including two ACT regulatory domains followed by a catalytic core typical of HAD (haloacid dehalogenase) phosphatases. Their in vitro catalytic properties are closely related as MmaSerB2 also depends on Mg2 thorn for the dephosphorylation of its substrate, Ophospho-L-serine (PS), and is most active at neutral pH and temperatures around 40 degrees C. Moreover, an enzyme kinetics study revealed that the enzyme is inhibited by PS as well, but at lower concentrations than MtbSerB2. Substrate inhibition could occur through the binding of PS in the second active site and/ or at the ACT domains interface. Finally, previously described beta-carboline MtbSerB2 inhibitors also decrease the phosphatase activity of MmaSerB2. Altogether, these results provide useful information when M.marinum is used as a model to study immune evasion in tuberculosis. (c) 2020 Elsevier Inc. All rights reserved.