[Pneumococcal HSP40 induces the immune response in mouse macrophages via p38MAPK and JNK signaling pathways]

To investigate the mechanism of immune response in mouse macrophage induced by Pneumococcal heat shock protein 40 (HSP40).

After recombinant HSP40 (rHSP40) underwent expression detection and purification, lipopolysaccharide (LPS) was removed from it. Then rHSP40 was used to stimulate bone marrow derived macrophages (BMDMs) derived from C57BL/6 wild-type mice. The mRNA levels of tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), IL-1β, IL-23p19, IL-12p40, IL-12p35 and IL-10 in BMDMs were determined by reverse transcription PCR; the expressions of TNF-α, IL-6 and IL-12p40 were measured by ELISA. After stimulated by rHSP40, the levels of TNF-α and IL-6 expressed by wide-type, TLR2-/- and TLR4-/- BMDMs were detected by ELISA. The effects of the pretreatment of mitogen-activated protein kinases (MAPK) inhibitors on the secretion of TNF-α and IL-6 induced by rHSP40 were also evaluated by ELISA in BMDMs. The phosphorylation levels of p38MAPK and c-Jun N-terminal kinase (JNK) were determined by Western blotting.

The rHSP40 protein reached a purity of more than 90%. It significantly enhanced the phosphorylation levels of p38MAPK and JNK as well as the expressions of TNF-α and IL-6. The p38MAPK and JNK inhibitors significantly suppressed the expressions of TNF-α and IL-6. The expressions of TNF-α and IL-6 in TLR4-/- BMDMs significantly decreased compared with wide-type BMDMs.

HSP40-induced immune response of mouse macrophages is regulated by p38MAPK and JNK signaling pathways, and this induction process depends on TLR4.