Trichinella spiralis HSP70 Modulates Macrophage Immunity via TLR2/MyD88/ERK, Reducing Muscle Larval Burden by 28% in Mice

Trichinellosis is a significant zoonotic parasitic disease, causing public health concerns and economic losses globally. Current treatments and preventive measures are often insufficient, highlighting the urgent need for effective vaccine candidates. Trichinella spiralis heat shock protein 70 (Ts-HSP70) has emerged as a promising immunomodulatory agent for vaccine development. However, the precise molecular mechanisms by which Ts-HSP70 interacts with host immune cells and orchestrates immune responses, particularly involving key innate immune receptors like Toll-like receptor 2 (TLR2), remain largely undefined.

Researchers investigated the immunomodulatory role of recombinant Ts-HSP70 (rTs-HSP70) in vitro using RAW264.7 macrophages. They confirmed the interaction between rTs-HSP70 and mouse TLR2 via co-immunoprecipitation and fluorescence colocalization assays. Macrophages were stimulated with rTs-HSP70 to assess effects on proliferation, phagocytosis, nitric oxide (NO) production, reactive oxygen species (ROS) generation, and cytokine mRNA expression via qPCR. Furthermore, the study explored the activation of NF-κB and MAPK signaling pathways. For in vivo assessment, rTs-HSP70 encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles was administered to mice to evaluate specific antibody responses and protective efficacy against Trichinella spiralis infection.

In vitro, rTs-HSP70 significantly enhanced RAW264.7 macrophage proliferation and phagocytic activity. It also markedly increased NO and ROS production, key indicators of macrophage activation. Gene expression analysis revealed that rTs-HSP70 upregulated the mRNA levels of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α, alongside the anti-inflammatory cytokine IL-10. These findings suggest a broad activation of macrophage immune functions. Furthermore, the study demonstrated that rTs-HSP70 induced the activation of both NF-κB and MAPK signaling pathways, crucial for immune gene expression. Functional inhibition assays specifically indicated that ERK activation, a component of the MAPK pathway, was partially dependent on the TLR2/MyD88 signaling axis. This establishes a direct mechanistic link. > In the in vivo mouse model, rTs-HSP70 encapsulated in PLGA nanoparticles elicited robust specific antibody responses and conferred partial protection, resulting in a 28.0% reduction in muscle larval burden.