Th1 and Th17 Cells in Tuberculosis: Protection, Pathology, and Biomarkers

Abstract

The outcome of Mycobacterium tuberculosis (Mtb) infection ranges from a complete pathogen clearance through asymptomatic latent infection (LTBI) to active tuberculosis (TB) disease. It is now understood that LTBI and active TB represent a continuous spectrum of states with different degrees of pathogen “activity,” host pathology, and immune reactivity. Therefore, it is important to differentiate LTBI and active TB and identify active TB stages. CD4+ T cells play critical role during Mtb infection by mediating protection, contributing to inflammation, and regulating immune response. Th1 and Th17 cells are the main effector CD4+ T cells during TB. Th1 cells have been shown to contribute to TB protection by secreting IFN-γ and activating antimycobacterial action in macrophages. Th17 induce neutrophilic inflammation, mediate tissue damage, and thus have been implicated in TB pathology. In recent years new findings have accumulated that alter our view on the role of Th1 and Th17 cells during Mtb infection. This review discusses these new results and how they can be implemented for TB diagnosis and monitoring.

Evaluation of the Anti-Mycobacterial, Anti-Oxidative and Anti-Proliferative Activities of Rubia Cordifolia Ethanolic Leaf Extract Sub-Fractions in Human Lymphocytes and Neutrophils

“…The other part of the investigations focused on screening the antioxidant and anti-proliferative activities of the ethanolic leaf extracts sub-fractions. Pro-inflammatory mediators play a significant part in protective immunity in tuberculosis and their maintenance and strict control is important to avoid immunopathic cases due to excessive and inappropriate production (Lyadova and Panteleev, 2015;Amaral et.al., 2016;Piñeros et.al., 2017). Only three of the sub-fractions: KF2-3.2B, K2F-3.3B and K2F-3.4 exhibited dose-dependent antioxidant and anti-proliferative activities that attained prominence from 50 µg/ml to 200 µg/ml.…”

The use of Phyllanthus niruri L. as an immunomodulator for the treatment of infectious diseases in clinical settings

“…IFN-γ is biologically involved in the activation of macrophages and natural immunity, promotion of antigen-presenting cells, and development of T-helper phenotype and humoral immunity [47]. Defects in IFN-γ secretion due to depressed Th1 responses are prevalent in TB patients [48].…”

Antigen-Specific IFN-γ Responses Correlate with the Activity of M. tuberculosis Infection but Are Not Associated with the Severity of Tuberculosis Disease

“…The concept is supported by the increased susceptibility of IFN- γ -deficient mice to experimental TB [4–6] and severe mycobacterial infections in humans bearing mutations in IFN- γ /IFN- γ axis [7–9]. However, several recent studies contradict this concept and suggest new roles for IFN- γ during TB (reviewed in [10]). In particular, in recent experimental studies IFN- γ was suggested to contribute to protection by inhibiting neutrophilic inflammation, whereas its role in the inhibition of Mtb replication was questioned [11–13].…”