Reprogrammed MDSCs promote Th1-dominant antitumour response via CD40 induced by autocrine TNF-α after combining cryo-thermal therapy with IL6 and IL17A neutralization.

Background: Mounting evidence shows that myeloid-derived suppressor cells (MDSCs) reprogramming can significantly enhance the outcomes of immunotherapy. However, the therapeutic potential of targeting MDSCs alone is limited by persistent immunosuppressive cytokines and cellular crosstalk. In our previous study, we found that novel cryo-thermal therapy (CTT) can drive MDSCs maturation and induce CD4⁺ T helper type (Th)1-dominant differentiation, improving long-term survival in spontaneous high metastatic mouse models. Considering the established roles of Interleukin (IL)-6 and IL-17A in non-small cell lung cancer (NSCLC) progression and immune evasion, we developed a combination strategy integrating cytokine neutralization with CTT (combination therapy) in LLC1 tumor-bearing mice. Although the combination therapy successfully promoted MDSCs maturation and Th1 differentiation, the underlying mechanistic basis remained unclear.

Methods: The combination therapy was implemented in LLC1 tumor-bearing mice. We then observed its impacts on MDSCs maturation and Th1 differentiation and explored the related mechanisms by examining various aspects including the expression of CD40, the reactive oxygen species (ROS)-nuclear factor-kappa B (NF-κB) pathway, and the induction of tumor necrosis factor-α (TNF-α).

Results: It was observed that the combination therapy increased the expression of CD40 on MDSCs through the ROS-NF-κB pathway-dependent TNF-α induction. This TNF-α-mediated CD40 upregulation facilitated Th1 polarization via CD40L engagement on CD4⁺ T cells. Our results provided the first mechanistic evidence that autocrine TNF-α production by reprogrammed MDSCs governs CD40 expression following combination therapy.

Conclusion: Our research elucidated the methods and mechanisms of MDSCs reprogramming and offered a promising therapeutic strategy for patients with NSCLC and other types of cancer.