ABSTRACT
Background: Head and neck squamous cell carcinoma (HNSCCs) is a common cancer type with a high mortality rate and poor prognosis. Recent studies have focused on the role of immune checkpoints in HNSCC progression and in their potential use as prognostic markers and immunotherapeutic candidates. Some immune checkpoints, such as PD-1 and PD-L1, have been studied thoroughly in HNSCC. Other molecules, such as indoleamine 2,3-dioxygenase 1 (IDO1), have been investigated minimally. Methods: IDO1 expression, prognostic potential, and association with the immune profile of HNSCC were explored using online databases, including GEPIA, UALCAN, TIMER2.0, cBioPortal, and LinkedOmics, which utilize TCGA datasets and are freely available for use. For validation purposes, seven pairs of primary and metastatic HNSCC were immunostained for IDO1. Results: Our analysis revealed significantly higher expression of IDO1 in HNSCC, especially in HPV+ SCCs compared with healthy control tissue. However, IDO1 expression showed weak to no prognostic potential for overall and disease-free survival in HNSCC. IDO1 expression in HNSCC was positively correlated with several immune-related molecules, including most of the immune checkpoints. Additionally, GO enrichment analysis revealed that several immune-related pathways are positively correlated with IDO1 expression in HNSCC, such as response to type I interferon and lymphocyte-mediated immunity pathways. Finally, IDO1 expression positively correlated with infiltration of most of the immune cells in HNSCC, such as CD4+ T cells, CD8+ T cells, M1 and M2 macrophages, dendritic cells, and B cells. Conclusion: IDO1 expression is closely correlated with the immune profile of the HNSCC. This observation should be explored further to elucidate the potential of targeting IDO1 as a novel immunotherapeutic approach for HNSCC.
ABSTRACT
A newly identified virus appeared in Wuhan, China, in December 2019, was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and caused the coronavirus disease 2019 (COVID-19). SARS-CoV-2 presents similarities with two previous coronavirus pandemics, MERS (Middle East Respiratory Syndrome) and SARSCoV, concerning phylogenetic origin, structural composition, and clinical symptoms, thus, leading to common pathogenic mechanisms. The purpose of this review is to declare the role of interleukin-6 (IL-6) in the pathogenesis, prognosis, and treatment of COVID-19 by comparing its effect on SARS-CoV and MERS cases. Increased levels of IL-6 comprise the key for the stimulation of cytokine storm and the progression of SARS, MERS, and COVID-19 cases. Especially, in COVID-19 patients, the overactivation of NF-kΒ, which is caused by the binding of coronavirus spike protein S to alveolar epithelial cells, up-regulates IL-6 and promotes its systematic circulation, causing alveolar damage and extrapulmonary injury. Additionally, IL-6 can be used to evaluate respiratory failure and identify asymptomatic patients. Tocilizumab (TCZ), a monoclonal antibody which blocks IL-6 signaling, comprises a remedial option against COVID-19. TCZ improves oxygenation, reduces fever, and decreases levels of IL-6. IL-6 plays a major role in the pathogenesis of cytokine storm and the progression of COVID-19 and may be used as a therapeutic target against COVID-19. However, further research is needed concerning the relation of IL-6 in COVID-19 cases, and more clinical trials are required to declare TCZ as a treatment option.