Role of innate immunity in tumor microenvironment of HPV-associated anal cancer: The hypothetical beneficial role of γδ T cells.

Abstract

HPV infection plays a crucial role in the formation of the tumor microenvironment, especially in tumors associated with the genital tract, anus, and oropharyngeal region. In this manuscript, we will discuss the main genetic characteristics of HPV and its transmission mechanisms, with a specific focus on the expression of the oncogenes E6 and E7. We will also address the major tumors HPV can generate and their associated epidemiology. In particular, persistent HPV infection induces the release of pro-inflammatory cytokines (such as IL-6 and IL-8), which promote angiogenesis and the recruitment of immunosuppressive immune cells. We will describe on the immune response to the infection, specifically in adaptive immunity, where the virus reduces the expression of MHC class I molecules on infected cells, preventing recognition by cytotoxic T cells. The innate immune response against HPV infection is often ineffective, allowing the virus to persist and contribute to tumor progression. The focus of this work will be on the innate response mediated by γδ T lymphocytes, a subset of CD3 + T cell. Indeed, they recognize HPV-infected cells without the need for antigen presentation by MHC molecules, secrete pro-inflammatory cytokines like IFN-γ and TNF-α, and directly kill HPV-infected cells through cytotoxic mechanisms. In summary, γδ T lymphocytes play an important role in the innate and adaptive immune response against HPV, but the effectiveness of their action can be reduced by the immune evasion mechanisms mediated by the virus. This may occur through the creation of an immunosuppressive environment with the release of immunosuppressive cytokines (such as IL-10 and TGF-β) that inhibit the function of these cells, allowing the virus to persist and contribute to tumor progression. This mechanism has not been well studied in the emerging anal cancer induced by HPV infection, so tracing the state of the art on these aspects could lead to an increase in research in this area and promote the creation of specific immunotherapies that enhance the role of these cells.