Leishmania infection of macrophages results in altered Ras isoforms expression and Toll-like receptor-2 (TLR2) expression and functions. Therefore, we examined whether TLR2 would selectively alter Ras isoforms' expression in macrophages. We observed that TLR2 ligands- Pam3CSK4, peptidoglycan (PGN), and FSL- selectively modulated the expression of Ras isoforms in BALB/c-derived elicited macrophages. Lentivirally-expressed TLR1-shRNA significantly reversed this Ras isoforms expression profile. TLR2-deficient L. major-infected macrophages and the lymph node cells from the L. major-infected mice showed similarly reversed Ras isoforms expression. Transfection of the macrophages with the siRNAs for the adaptors- Myeloid Differentiation factor 88 (MyD88) and Toll-Interleukin-1 Receptor (TIR) domain-containing adaptor protein (TIRAP)- or Interleukin-1 Receptor-Associated Kinases (IRAKs)- IRAK1 and IRAK4- significantly inhibited the L. major-induced down-regulation of K-Ras, and up-regulation of N-Ras and H-Ras, expression. The TLR1/TLR2-ligand Pam3CSK4 increased IL-10 and TGF-β expression in macrophages. Pam3CSK4 upregulated N-Ras and H-Ras, but down-regulated K-Ras, expression in C57BL/6 wild-type, but not in IL-10-deficient, macrophages. IL-10 or TGF-β signaling inhibition selectively regulated Ras isoforms expression. These observations indicate the specificity of the TLR2 regulation of Ras isoforms and their selective modulation by MyD88, TIRAP, and IRAKs, but not IL-10 or TGF-β, signaling.
Keywords: Leishmania; Lipophosphoglycan; Macrophages; Ras isoforms; TLR signaling.
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