Regulatory T Cells in Mycobacterium tuberculosis Infection

Abstract

Anti-inflammatory regulatory T cells have lately attracted attention as part of the immune response to Mycobacterium tuberculosis infection, where they counterbalance the protective but pro-inflammatory immune response mediated by Th17 cells and especially by the better-known Th1 cells. In chronic infectious diseases there is a delicate balance between pro- and anti-inflammatory responses. While Th1 and Th17 are needed in order to control infection by Mycobacterium tuberculosis, the inflammatory onset can ultimately become detrimental for the host. In this review, we assess current information on the controversy over whether counterbalancing regulatory T cells are promoting pathogen growth or protecting the host.

Keywords: Th17 cells; Treg cells; inflammation; tolerance; tuberculosis.

Figure 1

Hypothesis on the role of the balance between Tregs and Th17 cells in the development of TB. In a context of immunosuppression, where Tregs are predominant over Th17, Mtb disseminates more easily (A). The immune balance between these populations gives place to the encapsulation and control of lung lesions (B). If there is a high Th17 response, inflammation and neutrophils recruitment fuel the growth of the granuloma and development of TB (C).