mTORC1 mediates peptidoglycan induced inflammatory cytokines expression and NF-κB activation in macrophages

Area of Science:

• Immunology
• Cell Biology
• Microbiology

Background:

• Peptidoglycan (PGN) is a key bacterial cell wall component, particularly in Gram-positive bacteria, known to trigger inflammatory responses.
• The mammalian target of rapamycin (mTOR) pathway is implicated in regulating inflammatory cytokine production, but its specific role in PGN-induced inflammation remains unclear.

Purpose of the Study:

• To investigate the role and regulatory mechanisms of the mTOR signaling pathway in peptidoglycan-induced cytokine expression in mouse macrophages.
• To elucidate how mTORC1 influences the secretion of pro-inflammatory (IL-6, TNF-α) and anti-inflammatory (IL-10) cytokines.

Main Methods:

• Primary mouse macrophages were stimulated with peptidoglycan.
• Cytokine secretion levels (IL-6, TNF-α, IL-10) were measured.
• The activation of signaling pathways, including mTORC1, NF-κB, and STAT3, was analyzed.
• TLR1/TLR2 dependency was assessed.

Main Results:

• Peptidoglycan dose- and time-dependently upregulated IL-6, TNF-α, and IL-10 secretion.
• mTORC1 positively regulated IL-6 and TNF-α production while negatively regulating IL-10.
• mTORC1 mediated NF-κB activation through IκB-α degradation.
• The study identified involvement of mTOR, NF-κB, and STAT3 pathways via TLR1/TLR2.

Conclusions:

• The mTORC1 pathway is a critical regulator of the innate immune response to bacterial peptidoglycan in macrophages.
• mTORC1 modulates both pro- and anti-inflammatory cytokine balance during PGN exposure.
• This highlights mTORC1 as a potential therapeutic target for modulating bacterial-induced inflammation.