Papel da Pentraxina 3 na infecção pelo vírus SARS-CoV-2 e na inflamação pulmonar induzida pela proteína Nucleocapsídeo

Abstract

COVID-19 is a disease caused by the SARS-CoV-2 virus, that typically presents with mild symptoms but can evolve into severe manifestations such as systemic inflammation, acute respiratory distress syndrome (ARDS), thromboembolic complications, and cardiac damage, potentially leading to death. The risk of developing severe COVID-19 is associated with comorbidities, such as cardiovascular diseases, obesity, and chronic inflammation, among others. Understanding the disease mechanism is essential for identifying risks and improving clinical management. Pentraxin 3 (PTX3) is an acute-phase inflammatory protein associated with a poor prognosis in COVID-19. PTX3 is elevated in certain disease comorbidities, and studies suggest that this protein correlates with respiratory failure and mortality, serving as a more accurate predictor than C-reactive protein and IL-6. However, the role of PTX3 in COVID-19 has not yet been fully elucidated. This study aimed to characterize the role of PTX3 in SARS-CoV-2 infection and inflammation through in vitro and in vivo approaches. We performed a viral neutralization assay using Vero cells to assess whether PTX3 interferes with SARS-CoV-2 entry into cells. The virus (MOI: 0.01) was incubated with recombinant human PTX3 (rhPTX3) at different concentrations for 1 hour before the infection of Vero cells. The results showed that PTX3 does not interfere with viral entry, regardless of the dose used, suggesting that PTX3 does not affect the initial infection. To evaluate viral replication human lung cells (Calu-3) were treated with PTX3 1 hour before or after infection with Sars-Vov-2, simulating conditions in which PTX3 could be increased either before or after infection, respectively. The combination of PTX3 and the virus, pre-incubated for 1 hour, was also tested to evaluate whether the interaction between the virus and the protein could influence viral replication and the inflammatory response. Viral titration and RT-qPCR analyses were performed at 3, 8, 12, 18, 24, 36, 48, and 72 hours post-infection. The results indicated that PTX3 does not affect viral replication over time but downregulated the expression of the ACE2 receptor gene, TMPRSS2 protease, and the inflammatory genes TNFA, IL1B, PTX3, and IFNA. In post-infection treatment, rhPTX3 increased the expression of IFNB, CXCL10, and CXCL11, while other approaches attenuated the expression of these genes. In in vivo assays, pulmonary inflammation was induced in C57BL/6 mice by intranasal administration of the SARS-CoV-2 N protein (pN). We observed that treatment with recombinant mouse PTX3 (rmPTX3) administered 3 hours after pN resulted in more intense inflammatory responses, with greater tissue damage, increased cell counts in the bronchoalveolar lavage (BAL), and a more pronounced positive modulation of inflammatory cytokines compared to when treatment was administered before or concurrently with pN administration. Taken together, our results suggest that the role of PTX3 may vary depending on the stage of COVID-19, with initial protective effects and possible exacerbation of the inflammatory response in later stages when elevated following infection. Thus, PTX3 may represent a potential therapeutic target in COVID-19, depending on the timing of intervention.