Generation and characterization of CD43-floxed mice for conditional ablation in hematopoietic cells and T cells in immunity against pulmonary fungal infections - PROJECT SUMMARY Small Grant Program R03 proposal aims to generate CD43-floxed mice using the CRISPR-Cas9 technology and characterize the cell-specific antifungal functions of CD43 in hematopoietic and T cells using conditional CD43 KO mice. The preclinical model systems have been invaluable, providing insights into the human system, understanding the immune mechanisms, developing vaccines and immune therapeutics, and facilitating novel discoveries relevant to human medicine. Fungal infections, in the face of a lack of vaccines, cause significant mortality, rivaling TB and malaria, and instigated devastating complications during the COVID-19 pandemic. Further, the continuous rise in the immune-compromised or suppressed population by both nosocomial and non-nosocomial factors, as well as the expansion of fungal habitat due to climate change, has heightened the risk of fungal infections and posed a horde of public health challenges. A major limitation in the immune control of respiratory fungal infections is a lack of knowledge of protective host defense mechanisms, both innate and adaptive. Sialophorin (CD43) is implicated in viral, bacterial, parasitic, and fungal infections. CD43 research has shed light on its costimulatory/inhibitory, adhesive/anti-adhesive cell property, inhibiting or promoting apoptosis, receptor microbes/microbial product, binding several ligands, and in the aggressiveness of several lymphoid, myeloid, and epithelial cancer cells. The functionality and expression in several cell types with often counterintuitive phenotypes in the functions of CD43 have clouded our understanding and myopic views of its cell-specific functions. Regrettably, CD43-floxed mice are unavailable and are necessary to address much confounding research, including ours. Our preliminary data showed that CD43 (using global KO) is essential for immunity in a mouse model of pulmonary fungal infections, but we unexpectedly found its role in non-hematopoietic cells, contrary to our understanding its role in hematopoietic cells. In line with this, differing from the mouse model of viral infection, we found an essential role of CD43 (using global CD43 KO) for CD8+ T cell responses to fungal vaccinations and vaccine immunity. Therefore, we propose generating a CD43-floxed mouse to address the cell-specific role of CD43 in immunity against fungal infections by developing conditional CD43 KO. Our overarching hypothesis is that CD43 is integral in hematopoietic and non-hematopoietic cell responses in immunity against respiratory fungal infection. We aim to (1) generate CD43-floxed mice using the CRISPR-Cas9 technology to develop conditional KO mice and (2) Characterize CD43-floxed mice by generating conditional KO mice for immunity against fungal pneumonia and responses to the fungal vaccine. The outcomes of our projects will help advance our understanding of the cell- specific functions of CD43 during fungal infection and open universal applications in biomedical research to address confounding roles of CD43 in infectious, transplantation, tumor, and auto-immunity research thrusting new immunotherapeutic avenues.
