Avaliação do impacto do tratamento com a bactéria lática Weissella paramesenteroides WpK4 na resposta imunológica desencadeada in vitro pelo SARS-CoV-2 e in vivo pela proteína N do vírus

Abstract

A rapid and efficient inflammatory response is essential in controlling viral infection by individuals infected with SARS-CoV-2. However, what is observed in severe cases of COVID-19 is an excessive production of pro-inflammatory cytokines, known as a cytokine storm, accompanied by significant lung inflammation that triggers severe tissue damage and rapid progression to death. Therefore, inhibiting viral replication and modulating the inflammatory process to prevent an exacerbated immune response could be interesting therapeutic strategies to aid in the treatment of COVID-19. The lactic acid bacterium Weissella paramesenteroides WpK4, isolated from the nasal cavity of a healthy piglet, has shown a therapeutic potential in approaches against excessive inflammation in models. Therefore, this study aimed to evaluate the immunomodulatory role of WpK4 in COVID-19. To assess the impact of WpK4 treatment, Calu-3 lung cells were treated with the bacterium one hour after SARS-CoV-2 infection (therapeutic approach); one hour before infection viral (prophylactic approach); and also, with the combination of the bacterium pre-incubated for one hour with the SARS-CoV-2 virus (combination approach). In these in vitro experiments we observed inhibition of viral replication, resulting in a decrease in viral titers; an increase in the expression of the pro-inflammatory genes TNFA, IL1B, and CXCL10, as well as the antiviral gene IFNB; and inhibition of SARS-CoV-2-dependent increase in ACE2 expression in Calu-3 cells. These findings suggest a pro-inflammatory role of WpK4 that contributes to the control of the infection caused by SARS-CoV-2 in the cells. To investigate the underlying mechanisms of this apparent antiviral effect, as well as to understand the role of WpK4 in modulating the inflammatory response, C57BL/6 mice were intranasally inoculated with the N protein of SARS-CoV-2. In this model, the prophylactic administration of WpK4 exhibited a pro-inflammatory effect, resulting in moderate lung inflammation in the animals. In the therapeutic treatment, mild inflammation was observed, with no increase in cytokine levels in the bronchoalveolar lavage fluid. Conversely, severe pulmonary inflammation was detected in animals treated with the combination of the bacterium and protein N. Protein expression analysis by ELISA revealed an increase in the production of IL6, PTX3 and TNFA in these animals. The detrimental effect of the combination of the bacterium with the N protein needs further investigation. However, the data from therapeutic and prophylactic approaches indicate that WpK4 plays a pro-inflammatory role, has the potential to inhibit viral replication, and, when administered after exposure to the viral protein, may mitigate lung damage.