No abstract

Tumor cells overcome anti-tumor responses in part through immunosuppressive mechanisms. There are several immune modulatory mechanisms. Among them, adenosine is an important factor which is generated by both cancer and immune cells in tumor microenvironment to suppress anti-tumor responses. Two cell surface expressed molecules including CD73 and CD39 catalyze the generation of adenosine from adenosine triphosphate (ATP). The generation of adenosine can be enhanced under metabolic stress like tumor hypoxic conditions. Adenosine exerts its immune regulatory functions through four different adenosine receptors (ARs) including A1, A2A, A2B, and A3 which are expressed on various immune cells. Several studies have indicated the overexpression of adenosine generating enzymes and ARs in various cancers which was correlated with tumor progression. Since the signaling of ARs enhances tumor progression, their manipulation can be promising therapeutic approach in cancer therapy. Accordingly, several agonists and antagonists against ARs have been designed for cancer therapy. In this review, we will try to clarify the role of different ARs in the immunopathogenesis, as well as their role in the treatment of cancer.

Background The recent pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has elevated several clinical and scientific questions. These include how host genetic factors influence the pathogenesis and disease susceptibility. Therefore, the aim of this study was to evaluate the impact of interferon lambda 3 and 4 (IFNL3/4) gene polymorphisms and clinical parameters on the resistance and susceptibility to coronavirus disease 2019 (COVID-19) infection. Methods A total of 750 SARS-CoV-2 positive patients (375 survivors and 375 nonsurvivors) were included in this study. All single-nucleotide polymorphisms (SNPs) on IFNL3 (rs12979860, rs8099917, and rs12980275) and IFNL4 rs368234815 were genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) method. Results In this study, a higher viral load (low PCR Ct value) was shown in nonsurvivor patients. In survivor patients, the frequency of the favorable genotypes of IFNL3/4 SNPs (rs12979860 CC, rs12980275 AA, rs8099917 TT, and rs368234815 TT/TT) was significantly higher than in nonsurvivor patients. Multivariate logistic regression analysis has shown that a higher low-density lipoprotein (LDL), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and PCR Ct value, and lower 25-hydroxyvitamin D, and also IFNL3 rs12979860 TT, IFNL3 rs8099917 GG, IFNL3 rs12980275 GG, and IFNL4 rs368234815 ∆G/∆G genotypes were associated with the severity of COVID-19 infection. Conclusions The results of this study proved that the severity of COVID-19 infection was associated with clinical parameters and unfavorable genotypes of IFNL3/IFNL4 SNPs. Further studies in different parts of the world are needed to show the relationship between severity of COVID-19 infection and host genetic factors.