Toll-like receptor 2 selectively modulates Ras isoforms expression in Leishmania major infection

Area of Science:

• Immunology
• Cell Biology
• Molecular Biology

Background:

• Leishmania infection impacts macrophage Ras and Toll-like receptor-2 (TLR2) expression.
• TLR2 plays a crucial role in innate immune responses and macrophage function.

Purpose of the Study:

• To investigate if TLR2 selectively modulates Ras isoforms expression in macrophages.
• To elucidate the specific signaling pathways involved in TLR2-mediated Ras isoform regulation during Leishmania infection.

Main Methods:

• Macrophages were stimulated with TLR2 ligands (Pam3CSK4, PGN, FSL).
• Ras isoforms expression was analyzed using lentiviral-expressed TLR1-shRNA, TLR2-deficient macrophages, and siRNA transfection for MyD88, TIRAP, IRAK1, and IRAK4.
• Cytokine expression (IL-10, TGF-β) and signaling inhibition were assessed.

Main Results:

• TLR2 ligands selectively modulated Ras isoforms (K-Ras, N-Ras, H-Ras) expression in macrophages.
• TLR1 knockdown and TLR2 deficiency reversed these modulations.
• MyD88, TIRAP, IRAK1, and IRAK4 were identified as key adaptors in this pathway.
• Pam3CSK4-induced changes in Ras isoforms were dependent on IL-10, but IL-10 or TGF-β signaling inhibition did not directly regulate Ras isoforms.

Conclusions:

• TLR2 specifically regulates Ras isoforms expression in macrophages during Leishmania infection.
• The modulation is dependent on MyD88, TIRAP, and IRAKs signaling pathways.
• IL-10 and TGF-β signaling are downstream effectors rather than direct regulators of TLR2-mediated Ras isoform changes.