Nascimento, Rogério Silva do

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)

SUMMARY Tuberculosis induces diverse lesions, such as necrotic pneumonia, contributing to disease progression and transmission. Despite advances in understanding the role of ATP-gated P2RX7 ion channels in developing severe forms of tuberculosis, the regulation of this important signaling pathway remains unclear. Herein, we show that the ectonucleotidase CD39 plays an essential regulatory role in TB progression by preventing lung tissue damage, bacterial dissemination, and excessive inflammatory responses. Mechanistically, through its enzymatic activity on the cellular surface, CD39 protects infected macrophages from undergoing necrotic death mediated by P2RX7 activation. We proposed that by protecting macrophages from P2RX7-mediated cell death and bacterial dissemination, CD39 prevents the development of necrotic lesions. Altogether, these findings uncover a significant role for CD39 as an essential component of the molecular regulation underlying the development of severe tuberculosis. GRAPHICAL ABSTRACT Brief In tuberculosis, necrotic granuloma-like structures release extracellular ATP (eATP), which triggers P2RX7-mediated immune cell death. CD39 degrades eATP, preventing P2RX7 activation and promoting macrophage survival, thereby limiting inflammation, tissue damage, and bacterial dissemination.