Two-Step In Vitro Model to Evaluate the Cellular Immune Response to SARS-CoV-2

Juliana G. Melgaço; Tamiris Azamor; Andréa M. V. Silva; José Henrique R. Linhares; Tiago P. dos Santos; Ygara S. Mendes; Sheila M. B. de Lima; Camilla Bayma Fernandes; Jane da Silva; Alessandro F. de Souza; Luciana N. Tubarão; Danielle Brito e Cunha; Tamires B. S. Pereira; Catarina E. L. Menezes; Milene D. Miranda; Aline R. Matos; Braulia C. Caetano; Jéssica S. C. C. Martins; Thyago L. Calvo; Natalia F. Rodrigues; Carolina Q. Sacramento; Marilda M. Siqueira; Milton O. Moraes; Sotiris Missailidis; Patrícia C. C. Neves; Ana Paula D. Ano Bom

Two-Step In Vitro Model to Evaluate the Cellular Immune Response to SARS-CoV-2

2021

The cellular immune response plays an important role in COVID-19, caused by SARS-CoV-2. This feature makes use of in vitro models’ useful tools to evaluate vaccines and biopharmaceutical effects. Here, we developed a two-step model to evaluate the cellular immune response after SARS-CoV-2 infection-induced or spike protein stimulation in peripheral blood mononuclear cells (PBMC) from both unexposed and COVID-19 (primo-infected) individuals (Step1). Moreover, the supernatants of these cultures were used to evaluate its effects on lung cell lines (A549) (Step2). When PBMC from the unexposed were infected by SARS-CoV-2, cytotoxic natural killer and nonclassical monocytes expressing inflammatory cytokines genes were raised. The supernatant of these cells can induce apoptosis of A549 cells (mock vs. Step2 [mean]: 6.4% × 17.7%). Meanwhile, PBMCs from primo-infected presented their memory CD4<sup>+</sup> T cells activated with a high production of IFNG and antiviral genes. Supernatant from past COVID-19 subjects contributed to reduce apoptosis (mock vs. Step2 [ratio]: 7.2 × 1.4) and to elevate the antiviral activity (iNOS) of A549 cells (mock vs. Step2 [mean]: 31.5% × 55.7%). Our findings showed features of immune primary cells and lung cell lines response after SARS-CoV-2 or spike protein stimulation that can be used as an in vitro model to study the immunity effects after SARS-CoV-2 antigen exposure.

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