Cione, Marcos Vinícios Pinheiro

Abstract Lung cancer is the leading cause of cancer-related deaths worldwide, and despite advances in treatment, immune suppression remains an obstacle to effective therapy. Effector CD4+ T cells (CD4+ Teff) are critical for antitumor immunity, but their function is often inhibited by regulatory T cells (Treg), which accumulate in lung tumors and mediate suppressive functions through multiple mechanisms. This suppression leads to tumor progression and poor patient outcomes. However, the mechanisms underlying Treg-mediated suppression are not fully understood. Herein, we identify the extracellular adenosine 5-triphosphate receptor P2RX7 as a key regulator of Treg function in lung tumors. In a murine lung cancer model induced by Lewis lung carcinoma cells, we found that P2RX7 enhanced the suppressive capacity of tumor-infiltrating Tregs, promoting tumor growth. In T cell–specific P2RX7-knockout (P2RX7-KO) mice, reduced Treg infiltration was accompanied by increased CD4+ Teff accumulation and improved tumor control. Treg-specific P2RX7-KO mice exhibited reduced tumor growth, confirming a Treg-intrinsic role of P2RX7. Suppression assays revealed that tumor-infiltrating wild-type Tregs had greater suppressive activity compared with P2RX7-KO Tregs, which failed to inhibit type 1 and follicular helper T–like responses. This was associated with increased tumor-specific IgG production by lung B cells in P2RX7-KO mice. We also observed that wild-type Tregs expressed higher levels of the immunosuppressive molecule CTLA-4 when compared with P2RX7-KO Tregs. Thus, we conclude that P2RX7 expression on Tregs is essential for their suppressive function in lung cancer and targeting P2RX7 may constitute a strategy to improve lung cancer treatment by alleviating Treg-mediated immune suppression.

Abstract Description Vaccination is essential for preventing viral infections and promoting public health; however, its efficacy may vary due to factors such as the nature of the pathogen, vaccine type, and individual immune response. It is known that intranasal immunizations can enhance the immune response by stimulating tissue-resident memory T cells (TRMs), which promote early viral clearance at the infection site. Our study aims to optimize the generation and maintenance of TRMs in the lungs using purinergic signaling components as adjuvants. For this, we crossed B knockout mice with hACE2 mice, generating a B cell-deficient lineage capable of internalizing active SARS-CoV-2 (BKO-hACE2). C57BL/6 and BKO-hACE2 mice were immunized with inactivated SARS-CoV-2 receiving one intravenous dose followed by three intranasal booster doses. After 30 days, lungs were analyzed by flow cytometry and histopathology. Additionally, we evaluated the effects of ATP (0.5 mM to 10 mM) during immunizations, finding that lower doses (0.5 mM) increased the frequency of TRMs (CD4+ and CD8+), while higher doses reduced this population. This suggests that ATP may interact with the P2X7 receptor, promoting either proliferation or cell death. Although infection data did not provide conclusive evidence of T cell-mediated protection in the absence of antibodies, the potential of ATP as a possible adjuvant opens new avenues for enhancing immune responses in experimental models. Funding Sources FAPESP - 2023/15373-9 Topic Categories Viral Immunology (VIR)