Protective factors in the elderly: comparative iPSC-derived astrocytes proteome in Brazilian centenarians vs critically ill adults with COVID-19

COVID-19 has posed significant challenges globally, with Brazil being one of the hardest-hit countries due to the emergence of the Gamma.P1 variant of the SARS-CoV-2 virus. Despite the grim statistics of COVID-19-related deaths, there were notable cases of centenarians exhibiting resilience to severe illness caused by the virus. In this study, we aimed to elucidate the proteomic signatures associated with SARS-CoV-2 infection and individual factors that confer protection or susceptibility in human astrocytes derived from iPSC originated from mild infected centenary patients (n=4, CENT) and critically ill adults (n=3, ADU). Our analysis was focused on the Gamma.P1 (GAM) and Wuhan (WU) infection variants but also compared the response to age. Each patient-derived sample in the study has three conditions: cells infected with WU and GAM variant of SARS-CoV-2 virus, or the non-infected cells used as Control (Ctrl) for 21 samples in the cohort. DIA-MS analysis of astrocyte cells identified 6054 proteins and >3000 were quantified for each comparison group. Differential protein expression analysis was conducted to compare infected cells vs Ctrl considering age, virus type, and global infection as variables, revealing 1214 differentially regulated proteins (p<0.05, log |FC|>1). Functional enrichment analysis of CENT-derived astrocytes exhibited robust activation of gene expression regulation and cellular stress response pathways in response to infection, potentially contributing to their resilience against severe COVID-19. Notably, the enrichment in processes related to RNA stability, DNA damage response, and immune activation suggests a coordinated cellular defense mechanism against viral infection. In contrast, ADU-derived astrocytes showed a different response profile to viral infection. While they also exhibited immune activation, there was a prominent enrichment in proteolysis, metabolic processes, and protein complex organization. This indicates a more pronounced metabolic and proteolytic response in adult astrocytes, which may contribute to the pathogenesis of severe COVID-19 in this age group. Furthermore, functional enrichment analysis highlighted specific pathways modulated by SARS-CoV-2 infection. In CENT-derived astrocytes, pathways related to RNA stabilization, p53-mediated signaling, and cellular stress response were significantly enriched, indicating a concerted effort to mitigate the effects of viral stress. In ADU-derived astrocytes, processes associated with proteolysis, macromolecular complex assembly, and immune activation were predominant, reflecting a distinct cellular response profile. Overall, our findings provide valuable insights into the molecular mechanisms underlying COVID-19 pathology and the differential response of astrocytes to infection in mild centenarians vs critically ill adults for two virus strains.

Keywords: COVID-19, Wuhan, Gamma.P1, Brazilian centenarians, astrocytes, proteomic, DIA-MS