MicroRNA 205-5p and COVID-19 adverse outcomes: Potential molecular biomarker and regulator of the immune response

Coronavirus disease 2019 (COVID-19) is an acute respiratory infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The uncontrolled systemic inflammatory response, resulting from the release of large amounts of pro-inflammatory cytokines, is the main mechanism behind severe acute respiratory syndrome and multiple organ failure, the two main causes of death in COVID-19. Epigenetic mechanisms, such as gene expression regulation by microRNAs (miRs), may be at the basis of the immunological changes associated with COVID-19. Therefore, the main objective of the study was to evaluate whether the expression of miRNAs upon hospital admission could predict the risk of fatal COVID-19. To evaluate the level of circulating miRNAs, we used serum samples of COVID-19 patients collected upon hospital admission. Screening of differentially expressed miRNAs in fatal COVID-19 was performed by miRNA-Seq and the validation of miRNAs by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The Mann-Whitney test and receiver operating characteristic (ROC) curve were used to validate the miRNAs, whose potential signaling pathways and biological processes were identified through an in silico approach. A cohort of 100 COVID-19 patients was included in this study. By comparing the circulating levels of miRs between survivors and patients who died due to complications of the infection, we found that the expression of miR-205-5p was increased in those who died during hospitalization, and the expression of both miR-205-5p (area under the curve [AUC] = 0.62, 95% confidence interval [CI] = 0.5-0.7, P = 0.03) and miR-206 (AUC = 0.62, 95% CI = 0.5-0.7, P = 0.03) was increased in those who lately evolved to severe forms of the disease (AUC = 0.70, 95% CI = 0.6-0.8, P = 0.002)."In silico" analysis revealed that miR-205-5p has the potential to enhance the activation of NLPR3 inflammasome and to inhibit vascular endothelial growth factor (VEGF) pathways. Impaired innate immune response against SARS-CoV-2 may be explained by epigenetic mechanisms, which could form early biomarkers of adverse outcomes.

Thrombosis Occurrence in COVID-19 Compared With Other Infectious Causes of ARDS: A Contemporary Cohort

Thrombosis occurrence in coronavirus disease 2019 (COVID-19) has been mostly compared to historical cohorts of patients with other respiratory infections. We retrospectively evaluated the thrombotic events that occurred in a contemporary cohort of patients hospitalized between March and July 2020 for acute respiratory distress syndrome (ARDS) according to the Berlin Definition and compared those with positive and negative real-time polymerase chain reaction results for wild-type severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) using descriptive analysis. The association between COVID-19 and thrombotic risk was evaluated using logistic regression. 264 COVID-19-positive (56.8% male, 59.0 years [IQR 48.6-69.7], Padua score on admission 3.0 [2.0-3.0]) and 88 COVID-19-negative patients (58.0% male, 63.7 years [51.2-73.5], Padua score 3.0 [2.0-5.0]) were included. 10.2% of non-COVID-19 and 8.7% of COVID-19 patients presented≥1 clinically relevant thrombotic event confirmed by imaging exam. After adjustment for sex, Padua score, intensive care unit stay, thromboprophylaxis, and hospitalization length, the odds ratio for thrombosis in COVID-19 was 0.69 (95% CI, 0.30-1.64). We, therefore, conclude that infection-induced ARDS carries an inherent thrombotic risk, which was comparable between patients with COVID-19 and other respiratory infections in our contemporary cohort.

Adenosine diphosphate-induced aggregation is enhanced in platelets obtained from patients with thrombotic primary antiphospholipid syndrome (t-PAPS): Role of P2Y12 -cAMP signaling pathway

BACKGROUND

Thrombotic antiphospholipid syndrome (t-PAPS) is characterized by arterial, venous, or microvascular occlusions, which are explained, in part, by the presence of antiphospholipid (aPL) antibodies. Although there is much evidence indicating that isolated aPL antibodies increase the activity of platelets obtained from healthy volunteers, platelet function in t-PAPS has not been as widely studied.

OBJECTIVE

To evaluate platelet reactivity in t-PAPS patients.

METHODS

Platelet aggregation, protein expression, and cyclic nucleotide levels were carried out in platelet rich plasma (PRP) or washed platelets (WPs) obtained from t-PAPS or healthy volunteers.

RESULTS

ADP-induced aggregation was significantly higher in PRP obtained from t-PAPS than obtained from the control. The protein expression of P2Y12 receptor and Gs alpha was significantly higher and lower, respectively in WPs from t-PAPS patients. In PRP incubated with iloprost or sodium nitroprusside, the residual platelet reactivity induced by ADP was still higher in PRP from t-PAPS than from the control. Lower intracellular levels of cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) were observed in unstimulated PRP from t-PAPS patients. The protein expression of soluble guanylate cyclase subunits and phosphodiesterases types 3 and 5 did not differ. The antiplatelet activity of ticagrelor was similar between the groups and cilostazol significantly potentiated this response. Isolated aPL antibodies obtained from t-PAPS patients potentiated ADP-induced aggregation in healthy platelets but did not affect the inhibitory responses induced by iloprost or sodium nitroprusside.

CONCLUSIONS

The overexpression of P2Y12 receptor, accompanied by lower levels of cAMP and cGMP levels produced greater amplitude of ADP aggregation in platelets from t-PAPS patients.