Toll-Like Receptor 4 as an Immune Receptor AgainstMycobacterium tuberculosis: A Systematic Review

OBJECTIVE: To review the main Mycobacterium tuberculosis (Mtb) pathogen-associated molecular patterns (PAMPs) and the roles played by toll-like receptor (TLR)4 in determination of Mtb infection outcome. METHODS: Several scientific databases, including Scopus, PubMed, and Google Scholar, were used for searching appropriate research articles from the literature for information on our topic. RESULTS: TLR4 plays positive roles in induction of immune responses against Mtb and participates in eradication of the infection. Some limited investigations approved the roles of TLR4 in induction of apoptosis in macrophages during tuberculosis (TB) and attenuation of immune responses in some situations. CONCLUSIONS: TB outcome appears to be dependent on TLR4/Mtb interaction and several factors, including bacterial load and immune or nonimmune cells, as hosts. Also, other TLR/Mtb interactions can affect TLR4 responses.