LpqH

Mycobacteria express a number of pathogen-associated molecular patterns (PAMPs) on their surface. These are known to be recognized by certain pathogen recognition receptors (see below NOD-like receptors - NLR). Mycobacterial lipoproteins are important representatives of these PAMPs. The 19 kDa surface antigen LpqH plays an important role in the interaction between host and pathogen as well as in pleiotropic immune regulation. The protein is associated with host evolution and the maintenance of chronic infection.

LpqH is a 19 KDa lipoprotein anchored in the cell membrane that is involved in TLR2-dependent inhibition of MHC class II expression and antigen processing.

The lipoprotein plays an intricate role in the interactions between bacteria and the host immune system; some effects favor the host (induces interleukin 1-beta and IL-12 p40 (IL12B), both of which enhance the host immune response), while others favor the mycobacteria (increases growth in monocyte-derived macrophages and decreases MHC class II (MHC-II) expression and antigen processing in the host).

Induces the release of IL-12 p40 (IL12B, a proinflammatory cytokine) by monocyte cell lines via TLR2 and CD14.

Induces host (human) monocytes to produce TNF-alpha, IL-6 and IL-12 p40; LpqH is a more potent trigger than PstS1.

Inhibits MHC-II expression and antigen processing in host (mouse) macrophages via TLR2 (independent of TLR4), probably via lipid modification.

Identification of the antibody epitope of LpqH that is targeted by the natural mucosal immune system of an asymptomatic individual should be useful for future vaccine strategies.

1. Chatterjee S et al. (2022) High-resolution crystal structure of LpqH, an immunomodulatory surface lipoprotein of Mycobacterium tuberculosis reveals a distinct fold and a conserved cleft on its surface. Int J Biol Macromol 210:494-503.
2. Lancioni CL et al. (2011) Mycobacterium tuberculosis lipoproteins directly regulate human memory CD4(+) T cell activation via Toll-like receptors 1 and 2. Infect Immun 79:663-673.
3. Stewart GR et al. (2005) Effect of deletion or overexpression of the 19-kilodalton lipoprotein Rv3763 on the innate response to Mycobacterium tuberculosis. Infect Immun 73:6831-6837.