Innate immune cells in oral squamous cell carcinoma: Characteristics and therapeutic potential

Innate immune cells play an important role in the immune system and are mainly responsible for the rapid response to foreign pathogens, damaged tissues, or abnormal cells. However, their immunophenotype in oral squamous cell carcinoma (OSCC) is altered due to the influence of various components within the tumour microenvironment, including tumour cells, cancer associated fibroblasts, and the extracellular matrix. This immunophenotypic shift results in the suppression of anti-tumour-related immune functions and active participation in further remodelling of the tumour microenvironment. These remodelled innate immune cells are further involved in crosstalk with other components within the tumour microenvironment (TME), resulting in tumour immune reprogramming via multiple pathways in a positive feedback manner. This process facilitates tumour development, metastasis, and immune evasion, while impeding the efficacy of tumour immunotherapy. Consequently, disrupting the positive feedback loop through which innate immune cells are remodelled and actively reprogrammed within the tumour microenvironment may improve therapeutic outcomes and prognosis of patients with OSCC. Therefore, this article aimed to provide an overview of the reprogramming patterns of innate immune cells within the TME of OSCC, and the major pathways through which these cells participate in the regulation of TME. Additionally, this review summarises and discusses therapeutic approaches targeting innate immune cells in OSCC, and provides novel insights for the development of treatment strategies targeting the functions of innate immune cells in OSCC.