Effect of Toll-like receptor 4 deficiency on clinical severity and expression of Th1/Th2/Th17-associated cytokines in a murine model of experimental autoimmune neuritis.

Abstract

The aim was to observe the effect of Toll-like receptor 4 (TLR4) deficiency on clinical severity and expression of Th1/Th2/Th17-associated cytokines in experimental autoimmune neuritis (EAN). We selected C57BL/10 wild type (WT) mice and TLR4 knockout (KO) mice with the C57BL/10 background for induction of the EAN model by immunizing mice twice (days 0 and 8) via subcutaneous injection of 180 μg P0 peptide 180-199 emulsion in 25 μl of PBS and 0.5 mg Mycobacterium tuberculosis (Difco, USA) in 25 μl of Freund's incomplete adjuvant into the back of mice. The concentrations of serum cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF) were determined using the Ms Th1/Th2/Th17 CBA kit. We found that TLR4 deficiency could attenuate the clinical severity and delay the onset of EAN. Moreover, our data showed that the sera levels of IFN-γ, TNF, IL-6 and IL-17A were elevated in the WT mice with EAN when compared with the naive WT mice, but only the production of IL-17A was significantly lower in the TLR4 KO mice with EAN than in their WT counterparts. Based on these findings, TLR4 may contribute to the pathogenesis of EAN by regulating Th17 cells and the production of Th17-associated factors. However, the exact mechanism remains unclear and more evidence is needed to elucidate its role in EAN.