Incorporation of 5 methylcytidine alleviates innate immune response to self-amplifying RNA vaccine (preprint)

In order to improve vaccine effectiveness and safety profile of existing synthetic RNA-based vaccines, we have developed a self-amplifying RNA (saRNA)-based vaccine expressing membrane-anchored receptor binding domain (RBD) of SARS-CoV-2 S protein (S-RBD) and have demonstrated that a minimal dose of this saRNA vaccine elicits robust immune responses. Results from a recent clinical trial with 5-methylcytidine (5mC) incorporating saRNA vaccine demonstrated reduced vaccine-induced adverse effects while maintaining robust humoral responses. In this study, we investigate the mechanisms accounting for induction of efficient innate and adaptive immune responses and attenuated adverse effects induced by the 5mC-incorporated saRNA. We show that the 5mC-incorporating saRNA platform leads to prolonged and robust expression of antigen, while induction of type-I interferon (IFN-I), a key driver of reactogenicity, is attenuated in peripheral blood mononuclear cells (PBMCs), but not in macrophages and dendritic cells. Interestingly, we find that the major cellular source of IFN-I production in PBMCs is plasmacytoid dendritic cells (pDCs), which is attenuated upon 5mC incorporation in saRNA. In addition, we demonstrate that monocytes also play an important role in amplifying proinflammatory responses. Furthermore, we show that the detection of saRNA is mediated by a host cytosolic RNA sensor, RIG-I. Importantly, 5mC-incorporating saRNA vaccine candidate produced robust IgG responses against S-RBD upon injection in mice, thus providing strong support for the potential clinical use of 5mC-incorporating saRNA vaccines.

JAK inhibition reduces SARS-CoV-2 liver infectivity and modulates inflammatory responses to reduce morbidity and mortality.

Using AI, we identified baricitinib as having antiviral and anticytokine efficacy. We now show a 71% (95% CI 0.15 to 0.58) mortality benefit in 83 patients with moderate-severe SARS-CoV-2 pneumonia with few drug-induced adverse events, including a large elderly cohort (median age, 81 years). An additional 48 cases with mild-moderate pneumonia recovered uneventfully. Using organotypic 3D cultures of primary human liver cells, we demonstrate that interferon-α2 increases ACE2 expression and SARS-CoV-2 infectivity in parenchymal cells by greater than fivefold. RNA-seq reveals gene response signatures associated with platelet activation, fully inhibited by baricitinib. Using viral load quantifications and superresolution microscopy, we found that baricitinib exerts activity rapidly through the inhibition of host proteins (numb-associated kinases), uniquely among antivirals. This reveals mechanistic actions of a Janus kinase-1/2 inhibitor targeting viral entry, replication, and the cytokine storm and is associated with beneficial outcomes including in severely ill elderly patients, data that incentivize further randomized controlled trials.

Clinical Characteristics and Risk Factors of Respiratory Failure in a Cohort of Young Patients Requiring Hospital Admission with SARS-CoV2 Infection in Spain: Results of the Multicenter SEMI-COVID-19 Registry.

BACKGROUND: Age is a risk factor for COVID severity. Most studies performed in hospitalized patients with SARS-CoV2 infection have shown an over-representation of older patients and consequently few have properly defined COVID-19 in younger patients who require hospital admission. The aim of the present study was to analyze the clinical characteristics and risk factors for the development of respiratory failure among young (18 to 50 years) hospitalized patients with COVID-19. METHODS: This retrospective nationwide cohort study included hospitalized patients from 18 to 50 years old with confirmed COVID-19 between March 1, 2020, and July 2, 2020. All patient data were obtained from the SEMI-COVID Registry. Respiratory failure was defined as the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2 ratio) ≤200 mmHg or the need for mechanical ventilation and/or high-flow nasal cannula or the presence of acute respiratory distress syndrome. RESULTS: During the recruitment period, 15,034 patients were included in the SEMI-COVID-19 Registry, of whom 2327 (15.4%) were younger than 50 years. Respiratory failure developed in 343 (14.7%), while mortality occurred in 2.3%. Patients with respiratory failure showed a higher incidence of major adverse cardiac events (44 (13%) vs 14 (0.8%), p<0.001), venous thrombosis (23 (6.7%) vs 14 (0.8%), p<0.001), mortality (43 (12.5%) vs 7 (0.4%), p<0.001), and longer hospital stay (15 (9-24) vs 6 (4-9), p<0.001), than the remaining patients. In multivariate analysis, variables associated with the development of respiratory failure were obesity (odds ratio (OR), 2.42; 95% confidence interval (95% CI), 1.71 to 3.43; p<0.0001), alcohol abuse (OR, 2.40; 95% CI, 1.26 to 4.58; p=0.0076), sleep apnea syndrome (SAHS) (OR, 2.22; 95% CI, 1.07 to 3.43; p=0.032), Charlson index ≥1 (OR, 1.77; 95% CI, 1.25 to 2.52; p=0.0013), fever (OR, 1.58; 95% CI, 1.13 to 2.22; p=0.0075), lymphocytes ≤1100 cells/µL (OR, 1.67; 95% CI, 1.18 to 2.37; p=0.0033), LDH >320 U/I (OR, 1.69; 95% CI, 1.18 to 2.42; p=0.0039), AST >35 mg/dL (OR, 1.74; 95% CI, 1.2 to 2.52; p=0.003), sodium <135 mmol/L (OR, 2.32; 95% CI, 1.24 to 4.33; p=0.0079), and C-reactive protein >8 mg/dL (OR, 2.42; 95% CI, 1.72 to 3.41; p<0.0001). CONCLUSIONS: Young patients with COVID-19 requiring hospital admission showed a notable incidence of respiratory failure. Obesity, SAHS, alcohol abuse, and certain laboratory parameters were independently associated with the development of this complication. Patients who suffered respiratory failure had a higher mortality and a higher incidence of major cardiac events, venous thrombosis, and hospital stay.

Effect of in-hospital treatment with angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on mortality and complications in patients hospitalized for COVID-19: a large Spanish cohort study. (preprint)

BackgroundThe use of ACEI (Angiotensin-Converting Enzyme Inhibitor) and ARB (Angiotensin II Receptor Blocker) in COVID-19 remains controversial. Our main aim was to describe the effect of ACEI/ARB treatment during COVID-19 hospitalization on mortality and complications. MethodsRetrospective, observational, multicenter study, part of the SEMI-COVID-19 Registry, comparing patients with COVID-19 treated with ACEI/ARB during hospitalization to those not treated. The primary endpoint was incidence of the composite outcome of prognosis (IMV [Invasive Mechanical Ventilation], NIMV [Non-Invasive Mechanical Ventilation], ICU admission [Intensive Care Unit], and/or all-cause mortality). The secondary endpoint was incidence of MACE (Major Adverse Cardiovascular Events). We evaluated both outcomes in patients whose treatment with ACEI/ARB continued or was withdrawn during hospitalization. ResultsBetween February and June 2020, 11,205 patients were included, with mean age 67 years (SD=16.3) and 43.1% female; 2,162 patients received ACEI/ARB treatment. ACEI/ARB treatment showed a protective effect on all-cause mortality (p<.0001). In hypertensive patients it was also protective in terms of IMV, ICU admission, and the composite outcome of prognosis (p<.0001 for all). No differences were found in incidence of MACE. Patients previously treated with ACEI/ARB who continued treatment during hospitalization had a lower incidence of the composite outcome of prognosis than those whose treatment was withdrawn (RR 0.67, 95%CI 0.63-0.76). ARB had a more beneficial effect on survival than ACEI (HR 0.77, 95%CI 0.62-0.96). ConclusionACEI/ARB treatment during COVID-19 hospitalization had a protective effect on mortality. The benefits were greater in hypertensive patients, those who continued treatment during hospitalization, and those taking ARB. SummaryTreatment with ACEI/ARB during COVID-19 hospitalization showed a beneficial effect on mortality in the general population. The benefit was greater in hypertensive patients, in those who maintained treatment during hospitalization and those taking ARB.