Colchicine reduces the activation of NLRP3 inflammasome in COVID-19 patients.

OBJECTIVE: To evaluate whether colchicine treatment was associated with the inhibition of NLRP3 inflammasome activation in patients with COVID-19. METHODS: We present a post hoc analysis from a double-blinded placebo-controlled randomized clinical trial (RCT) on the effect of colchicine for the treatment of COVID-19. Serum levels of NOD-like receptor protein 3 (NLRP3) inflammasome products-active caspase-1 (Casp1p20), IL-1ß, and IL-18-were assessed at enrollment and after 48-72 h of treatment in patients receiving standard-of-care (SOC) plus placebo vs. those receiving SOC plus colchicine. The colchicine regimen was 0.5 mg tid for 5 days, followed by 0.5 mg bid for another 5 days. RESULTS: Thirty-six patients received SOC plus colchicine, and thirty-six received SOC plus placebo. Colchicine reduced the need for supplemental oxygen and the length of hospitalization. On Days 2-3, colchicine lowered the serum levels of Casp1p20 and IL-18, but not IL-1ß. CONCLUSION: Treatment with colchicine inhibited the activation of the NLRP3 inflammasome, an event triggering the 'cytokine storm' in COVID-19. TRIAL REGISTRATION NUMBERS: RBR-8jyhxh.

ANTIVIRAL RESPONSE OF NATURAL KILLER CELLS IN EARLY STAGE OF COVID-19 PATIENTS

Backgroung: COVID-19 pandemic (SARS-CoV-2) has affected an increasing number of people worldwide, with death rates higher than previous viral epidemics. It is possible that NK cells, known to have great cytokine secreting potential are competent at the onset of the condition and that in some individuals, the viral load is able to exhaust them. Balance between tolerant (CD27- CD11b-), secretory (CD27+ CD11b-/ CD27+ CD11b+) and cytotoxic (CD27- CD11b+) NK cells involved in the inflammatory response and their anti-SARS-CoV-2 activity are still not well established. Strategies that can restore function of NK cells against the virus are worth investigating. Here, we aimed to characterize NK cells frequency, functional subtypes and maturation in early phase of COVID-19 patients, by Multiparametric Flow Cytometry (MFC). Methods: Peripheral blood from 15 COVID-19 patients in early stage of infection (day 1-14, confirmed by RT-PCR), categorized according comorbidities in: G1 (not oncologic;n = 6), G2 (oncologic;n = 3), G3 (hematologic neoplasms;n = 3) and G4 (without comorbidities;n = 3), and 10 healthy samples enrolled the study. Clinical and laboratorial data were collected from electronic medical records. Samples were stained with CD45, CD19, CD3, CD56, CD11b, CD27, acquired on a FACS Canto II (BD Biosciences) and data analyzed with FlowJo V10 software. Results: A lower frequency of lymphocytes was observed in the disease when compared to controls (P < 0.0001) and frequency of NK cells were similar in both groups (P = 0.6605). Although frequency of CD27- CD11b- NK cells was lower in the disease (P = 0.0109), there was a significantly higher frequency of CD27+ CD11b- NK cells in COVID-19 samples when compared to controls (P < 0.0001), featuring a mostly immature profile in the disease. On the other hand, no statistical significance was observed regarding the frequencies of CD27+ CD11b+ (P = 0.1370) and CD27- CD11b+ NK cells with a more mature profile (P = 0.3094). Amongst disease groups, no statistical significance was found regarding frequency of NK cells and G1 showed lower frequency of CD27- CD11b- NK cells (P = 0.0226), while G3 group had an increased frequency of CD27+ CD11b- NK cells (P = 0.0238) when compared to the other groups and controls. Finally, no statistical significance was found in the frequency of CD27+ CD11b+ (P = 0.6691) and CD27- CD11b+ (P = 0.6270) NK cells between disease groups and controls. Conclusion: Although the frequency of NK cells did not show a significant difference between COVID-19 patients and healthy controls, our findings showed a possible change in their maturation profile, which seems to be inversely proportional to normal, with the frequency of CD27+ CD11b- NK cells considerably higher in the disease. This phenotype is directly associated with secretory function of a more immature NK cell and is responsible for triggering inflammatory responses that could lead to severe respiratory failure, what seems to be consistent with COVID-19 profile. A high frequency of cytotoxic cells was observed, which seemed to be similar to what we found in normal heathy samples. Even though unregulated maturation might be associated to a dysfunctional mature NK cell, additional studies of cytotoxicity and activation of NK cells in COVID-19 are required to affirm whether there is functional exhaustion or hyperactivation of the cytotoxic subtypes of these cells.

Prevalence of virological and serological markers of SARS-CoV-2 infection in the population of Ribeirão Preto, Southeast Brazil: an epidemiological survey

INTRODUCTION: This epidemiological household survey aimed to estimate the prevalence of the current and past SARS-CoV-2 infections in Ribeirão Preto, a municipality of southeast Brazil. METHODS: The survey was conducted in two phases using a clustered sampling scheme. The first phase spanned May 1-3 and involved 709 participants. The second phase spanned June 11-14, 2020, and involved 646 participants. RESULTS: During the first phase, RT-PCR performed on nasopharyngeal swabs was positive at 0.14%. The serological tests were positive in 1.27% of the patients during the first phase and 2.79% during the second phase. People living in households with more than five members had a prevalence of 10.83% (95%CI: 1.58-74.27) higher than those living alone or with someone other. Considering the proportion of the positive serological test results with sex and age adjustments, approximately 2.37% (95%CI: 1.32-3.42) of the population had been cumulatively infected by mid-June 2020, which is equivalent to 16,670 people (95%CI: 9,267-24,074). Considering that 68 deaths from the disease in the residents of the city had been confirmed as at the date of the second phase of the survey, the infection fatality rate was estimated to be 0.41% (95%CI: 0.28-0.73). Our results suggest that approximately 88% of the cases of SARS-CoV-2 infection at the time of the survey were not reported to the local epidemiological surveillance service. CONCLUSIONS: The findings of this study provide in-depth knowledge of the COVID-19 pandemic in Brazil and are helpful for the preventive and decision-making policies of public managers.