Recombinant CD137-Fc, its synthesis, and applications for improving the immune system functions, such as tumor immunotherapy and to reduce the inflammation due to the novel coronavirus

Soluble CD137 as a potential biomarker for severe COVID-19

Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a highly pathogenic infection responsible for the world pandemic in 2020. COVID-19 is characterized by an increased number of critically ill patients with a high risk of health care system collapse. Therefore, the search for severity biomarkers and potential therapies is crucial. In this study, we evaluated SARS-CoV-2 -induced cytokines, cytokines receptors and growth factors profile, in critical COVID-19 patients admitted in intensive care unit (ICU) aiming to identify potential biomarkers and therapeutic targets. We designed a prospective study enrolling 62 adults with severe COVID-19 during the first two Brazilian COVID-19 waves (from May to July 2020 and December 2020 to May 2021), convenience samples recruitment in first 24 hours and then, every 4 days until day 20 of ICU admission from a tertiary hospital in São Paulo, Brazil. Controls were healthy blood donors. Whole blood was used to evaluate 17 cytokines, cytokines receptors and growth factors. Due to low mortality rate, we used the need of mechanical ventilation as primary endpoint. In our analysis, we found a different pattern in soluble CD137 (sCD137) in critically ill patients with COVID-19, with a direct relationship between increased levels and worse clinical outcome. sCD137 was related with increased risk of mechanical ventilation and World Health Organization (WHO) clinical score for disease severity. CD137 is a tumor necrosis factor receptor (TNF) family member, mainly responsible for T-cell activation. Soluble isoforms of immune checkpoints competitively regulate function of their membrane-bound counterparts. Our study demonstrated the onward increase in sCD137 levels during severe SARS-CoV-2 infection and its correlation with worse outcomes, suggesting sCD137 as a potential reliable severity biomarker.

Recombinant CD137-Fc, its synthesis, and applications for improving the immune system functions, such as tumor immunotherapy and to reduce the inflammation due to the novel coronavirus

CD137 (ILA/4-1BB), a member of tumor necrosis factor receptor superfamily, is one of the most important T cell costimulatory molecules. Interaction of this molecule with its ligand transmits a two-way signal that activates both T lymphocyte and antigen presenting cells. The soluble form of CD137 (sCD137) reduces the activity of its membrane isoform and is associated with T lymphocyte activation-induced cell death. Recombinant CD137-Fc may be used to treat cancers, autoimmune disorders and viral infections. It may also be useful for management of coronavirus infection. The 1276 bp DNA sequence encoded CD137-Fc recombinant protein was prepared and subcloned into lentiviral vector and expressed in transduced CHO-K1 eukaryotic cells. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot analysis, and enzyme-linked immunosorbent assay analysis results demonstrated that the expression of the 70-kDa CD137-Fc molecule was detectable without any degradation. This study helps to confirm previous research suggesting the use of this recombinant protein as a promising solution for the treatment of virus infections. CD137-Fc fusion protein could also make immunotherapy more effective for some diseases. This product is widely used in novel medical treatments, including cell-based immunotherapy such as dendritic cell, CAR T and CAR NK therapy. Its production and usage in research and treatment is noticeable also in current coronavirus disease 2019 pandemic.