Concanavalin A induced expression of Toll-like receptors in murine peritoneal macrophages in vitro

The differential expression of Toll-like receptors (TLRs 1–9) and their associated proteins in murine peritoneal macrophages in vitro, on treatment with plant lectin concanavalin A (Con A) has been investigated. It is observed that there is enhanced expression of TLRs 2–9 and downstream molecules—MyD88, IRAK1, TRAF6 and IRF3 in murine peritoneal macrophages on in vitro treatment with Con A. Pretreatment of macrophages with inhibitors of JNK, p38, p42/44 and NF-κB, significantly decreased the Con A induced expression of TLRs. When cells are pre-treated with Con A and subsequently treated with TLR ligands—Zymosan A, PolyI:C, LPS, CpG DNA, there is enhanced production of proinflammatory cytokines (TNF-α, IL-1β, IL-12 and IFN-γ,), nitric oxide and iNOS expression in murine peritoneal macrophages. The results suggest that treatment of macrophages with Con A renders them more susceptible to subsequent activation and induction of proinflammatory cytokines and nitric oxide production by different TLR ligands.