Motolimod

A challenge for cancer vaccines is to elicit immune responses of sufficient magnitude to control malignant tumor growth and spread. In this study, we iteratively screened a panel of 22 lipid-phase vaccine adjuvants in mice for the elicitation of neoantigen-specific CD8⁺ T cell responses, using an integrated peptide-lipid nanoparticle approach. CL401, a dual Toll-like receptor 2/7 (TLR2/7) adjuvant rapidly induced neoantigen-specific T cell responses and improved lymphatic drainage and uptake of the particle. Additional rounds of in vivo screening identified complementary adjuvants which targeted TLR4 (3D6A-PHAD adjuvant), TLR8 (motolimod), and inflammasome (QS-21) pathways and synergized to enhance cytokine secretion in antigen presenting cells and vaccine-elicited neoantigen-specific CD8⁺ T cells. Co-delivery of adjuvants and antigens led to effective immune responses which regressed large established tumors, synergized with immune checkpoint blockade, and inhibited lung nodules in an experimental metastasis model, without overt toxicity or reactogenicity. We conclude that iterative adjuvant screening, performed in mice in vivo, can identify useful adjuvant combinations that hold potential for therapeutic cancer vaccine research.

Innate immunity significantly contributes to SSc pathogenesis. TLR8 is an important innate immune mediator that is implicated in autoimmunity and fibrosis. However, the expression, mechanism of action, and pathogenic role of TLR8 in SSc remain unclear. The aim of this study was to explore the roles and underlying mechanisms of TLR8 in SSc.

The expression of TLR8 was analysed, based on a public dataset, and then verified in skin tissues and skin fibroblasts of SSc patients. The role of TLR8 in inflammation and fibrosis was investigated using a TLR8-overexpression vector, activator (VTX-2337), inhibitor (cu-cpt-8m), and TLR8 siRNA in skin fibroblasts. The pathogenic role of TLR8 in skin inflammation and fibrosis was further validated in a bleomycin (BLM)-induced mouse skin inflammation and fibrosis model.

TLR8 levels were significantly elevated in SSc skin tissues and myofibroblasts, along with significant activation of the TLR8 pathway. In vitro studies showed that overexpression or activation of TLR8 by a recombinant plasmid or VTX-2337 upregulated IL-6, IL-1β, COL I, COL III and α-SMA in skin fibroblasts. Consistently, both TLR8-siRNA and cu-cpt-8m reversed the phenotypes observed in TLR8-activating fibroblasts. Mechanistically, TLR8 induces skin fibrosis and inflammation in a manner dependent on the MAPK, NF-κB and SMAD2/3 pathways. Subcutaneous injection of cu-cpt-8m significantly alleviated BLM-induced skin inflammation and fibrosis in vivo.

TLR8 might be a promising therapeutic target for improving the treatment strategy for skin inflammation and fibrosis in SSc.