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Preprint in English | medRxiv | ID: ppmedrxiv-22273418


BackgroundTherapeutic effects of steroids on acute respiratory distress syndrome (ARDS) requiring mechanical ventilation (MV) have been reported. However, predictive indicators of early weaning from MV post-treatment have not yet been defined, making treating established ARDS challenging. Interleukin (IL)-6 has been associated with the pathogenesis of ARDS. ObjectiveOur aim was to clarify clinical utility of IL-6 level in ventilated patients with established ARDS. MethodsClinical, treatment, and outcome data were evaluated in 119 invasively ventilated patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-mediated ARDS. Plasma levels of IL-6 and C-reactive protein (CRP) were measured on days 1, 4, and 7 after intubation. ResultsFifty-two patients were treated with dexamethasone (steroid group), while the remaining 67 patients were not (non-steroid group). Duration of MV use was significantly shorter in the steroid group compared to non-steroid group (11.5{+/-}0.6 vs. 16.1{+/-}1.0 days, P = 0.0005, respectively) along with significantly decreased levels of IL-6 and CRP. Even when restricted to the steroid group, among variables post-MV, IL-6 level on day 7 was most closely correlated with duration of MV use (Spearmans rank correlation coefficient [{rho}] = 0.73, P < 0.0001), followed by CRP level on day 7 and the percentage change in IL-6 or CRP levels between day 1 and day 7. Moreover, among these variables, IL-6 levels on day 7 showed the highest accuracy for withdrawal from MV within 11 days (AUC: 0.88), with optimal cutoff value of 20.6 pg/mL. Consistently, the rate of MV weaning increased significantly earlier in patients with low IL-6 ([≤] 20.6 pg/mL) than in those with high IL-6 (> 20.6 pg/mL) (log-rank test P < 0.0001). ConclusionsIn invasively ventilated patients with established ARDS due to SARS-CoV-2, plasma IL-6 levels served as a predictor of early withdrawal from MV after dexamethasone administration.

Preprint in English | medRxiv | ID: ppmedrxiv-22269723


BackgroundAcute respiratory distress syndrome (ARDS) with COVID-19 is aggravated by hyperinflammatory responses even after the peak of viral load has passed; however, its underlying mechanisms remain unclear. Alveolar epithelial injury is reported to be a very early event in ARDS with COVID-19. Herein, we assessed whether necrosis of alveolar epithelial cells and subsequent releases of damage associated molecular patterns (DAMPs) at an early disease stage aggravates ARDS with COVID-19 MethodsWe analyzed the levels of cytokeratin18-M65, an epithelial total cell death marker; CK18-M30, an epithelial apoptosis-specific marker; and HMGB-1, one of the DAMPs released from necrotic cells, in patients with COVID-19 with and without ARDS and healthy adults, in addition to the circulating alveolar epithelial and endothelial injury markers, namely sRAGE, angiopoietin-2, and surfactant protein-D. Molecular mechanisms of alveolar epithelial cell death and effects of neutralization on alveolar tissue injury were assessed using a mouse model mimicking COVID-19-induced ARDS. ResultsCOVID-19-induced ARDS was characterized by the elevation of sRAGE, an epithelial injury marker, at a very early disease stage. Although both serum levels of CK18-M65 and CK18-M30 were elevated in COVID-19-induced ARDS, the median CK18-M30/M65 ratio, an indicator of the fraction of apoptosis among total epithelial cell death, was 31.5% in serum from COVID-19 patients with ARDS, a value significantly lower than that of non-ARDS patients or healthy subjects. Moreover, the median M30/M65 ratio in bronchoalveolar lavage fluid (BALF) in COVID-19-induced ARDS was 27.8%, indicating that alveolar epithelial cell death is mainly caused by necrosis. Serum levels of HMGB-1 were also significantly elevated in ARDS versus non-ARDS patients. In a mouse model mimicking COVID-19-induced ARDS, the ratio of CK18-M30 to a total epithelial cell death marker in BALF was also lower than that in control subjects. Moreover, the alveolar epithelial cell necrosis involved two forms of programmed necrosis: necroptosis and pyroptosis. Finally, neutralization of HMGB-1 attenuated alveolar tissue injury in the mouse model. ConclusionsNecrosis, including necroptosis and pyroptosis, seems to be the primary form of alveolar epithelial cell death and subsequent release of DAMPs is a potential driver of COVID-19-induced ARDS.

Preprint in English | medRxiv | ID: ppmedrxiv-20158410


SARS-CoV-2 neutralizing antibodies confer protective immunity against reinfection. We have developed a rapid test for screening SARS-CoV-2 neutralization antibodies using genome-free virus-like particles incorporated with a small luciferase peptide, HiBiT. Their entry into LgBiT-expressing target cells reconstitutes NanoLuc luciferase readily detected by a luminometer. This newly developed HiBiT-tagged Virus-like particle-based Neutralization Test (hiVNT) can readily quantify SARS-CoV-2 neutralizing antibodies within three hours with a high-throughput in a low biosafety setting. Moreover, the neutralizing activity obtained from hiVNT was highly consistent with that measured by the conventional neutralization test using authentic SARS-CoV-2. Furthermore, antibody responses to both viral spike and nucleocapsid proteins correlated with the neutralization activity assessed by hiVNT. Our newly-developed hiVNT could be instrumental to survey individuals for the presence of functional neutralizing antibody against SARS-CoV-2.