The Human Phospholipase B-II Precursor (HPLBII-P) in Urine as a Novel Biomarker of Glomerular Activity in COVID-19 and Diabetes Mellitus (preprint)

The human phospholipase B-II precursor (HPLBII-P) was originally purified from white blood cells but is also found in other cellular structures such as kidney glomeruli and tubuli. The objective of this report was to investigate the relationship of HPLBII-P in urine to acute kidney injury in patients with COVID-19 Methods Urine was collected at admission from 132 COVID-19 patients admitted to the intensive care units (ICU) because of respiratory failure. HPLBII-P was measured by a sensitive ELISA. For comparison, HNL was measured in urine, by the ELISA configured with mabs 763/8F, as a sign of tubular affection in addition to routine biomarkers of kidney disease Results Overall, the concentrations of urinary HPLBII-P were almost 3-fold higher in COVID-19 patients as compared to healthy controls (p

Echocardiographic characterisation in severe Covid-19 with respiratory failure - an observational study. (preprint)

ObjectiveWe aimed to investigate cardiac effects of severe SARS-CoV-2 and the importance of echocardiography-assessment and biomarkers. MethodsThis is an observational study of the first patients admitted to intensive care due to SARS-CoV-2-respiratory failure. Thirty-four underwent echocardiography of which twenty-five were included, compared to forty-four non-echo patients. Exclusion was based on absence of normofrequent sinus rhythm and/or mechanical respiratory support. Biomarkers were analysed on clinical indication. ResultsMortality was higher in the echo-compared to non-echo group (44 % vs. 16%, p<0.05). Right-sided parameters were not under significant strain. Tricuspid valve regurgitation velocity indicated how increased pulmonary pressure was associated with mortality (survivors: 2.51 {+/-} 0.01 m/s vs. non-survivors: 3.06 {+/-} 0.11 m/s, p<0.05), before multiple comparison-correction. Setting cut-off for pulmonary hypertension to 2.8 m/s generated p<0.01 using frequency distribution testing. Cardiac markers, high sensitivity cardiac troponin I and N-terminal pro brain natriuretic peptide, and D-dimer were higher in the echocardiography group. (hs-TnI (ng/L): echo : 133 {+/-} 45 vs. non-echo: 81.3 {+/-} 45, p<0.01; NT-proBNP (ng/L): echo: 2959 {+/-} 573 vs. non-echo: 1641 {+/-} 420, p<0.001; D-dimer (mg/L): echo: 16.1 {+/-} 3.7 vs. non-echo: 6.1 {+/-} 1.5, p<0.01) and non-survivor group (hs-TnI (ng/L): survivors: 59.1 {+/-} 21 vs. non-survivors: 211 {+/-} 105, p<0.0001; NT-proBNP (ng/L): survivors: 1310 {+/-} 314 vs. non-survivors: 4065 {+/-} 740, p<0.0001; D-dimer (mg/L): survivors: 7.2 {+/-} 1.5 vs. non-survivors: 17.1 {+/-} 4.8, p<0.01). Tricuspid regurgitation velocity was positively correlated with cardiac troponin I (r=0.93, r2=0.74, p<0.001). ConclusionsThese results suggest there is no negative effect on cardiac function in critical SARS-CoV-2. Pulmonary pressure appears higher amongst non-survivors indicating pulmonary disease as the driver of mortality. Echocardiography was more commonly performed in the non-survivor group, and cardiac biomarkers as well as D-dimer was higher in the non-survivor group suggesting they carry negative prognostic values. Trial registration numberThis is an observational study from patients included in "Clinical trials NCT04316884" Strength and limitations of this study- The patient cohort is recruited from consecutive patients admitted to the ICU in need of mechanical respiratory support independent of background which makes it relevant to clinical practice. - The echocardiographic image acquisition was carried out by hospital assigned agents on clinical indication, which makes the results applicable in a clinical setting. - Since the image acquisition was carried out on a clinical indication, the results may be skewed towards the false positive if applied to all Covid19 patients.

Genome-wide Association Study of Long COVID (preprint)

Infections can lead to persistent or long-term symptoms and diseases such as shingles after varicella zoster, cancers after human papillomavirus, or rheumatic fever after streptococcal infections(1,2). Similarly, infection by SARS-CoV-2 can result in Long COVID, a condition characterized by symptoms of fatigue and pulmonary and cognitive dysfunction(3-5). The biological mechanisms that contribute to the development of Long COVID remain to be clarified. We leveraged the COVID-19 Host Genetics Initiative(6,7) to perform a genome-wide association study for Long COVID including up to 6,450 Long COVID cases and 1,093,995 population controls from 24 studies across 16 countries. We identified the first genome-wide significant association for Long COVID at the FOXP4 locus. FOXP4 has been previously associated with COVID-19 severity(6), lung function(8), and cancers(9), suggesting a broader role for lung function in the pathophysiology of Long COVID. While we identify COVID-19 severity as a causal risk factor for Long COVID, the impact of the genetic risk factor located in the FOXP4 locus could not be solely explained by its association to severe COVID-19. Our findings further support the role of pulmonary dysfunction and COVID-19 severity in the development of Long COVID.

Sustained IFN signaling is associated with delayed development of SARS-CoV-2-specific immunity (preprint)

Plasma RNAemia, delayed antibody responses and inflammation predict COVID-19 outcomes, but the mechanisms underlying these immunovirological patterns are poorly understood. We profile 782 longitudinal plasma samples from 318 hospitalized COVID-19 patients. Integrated analysis using k-means reveal four patient clusters in a discovery cohort: mechanically ventilated critically-ill cases are subdivided into good prognosis and high-fatality clusters (reproduced in a validation cohort), while non-critical survivors are delineated by high and low antibody responses. Only the high-fatality cluster is enriched for transcriptomic signatures associated with COVID-19 severity, and each cluster has distinct RBD-specific antibody elicitation kinetics. Both critical and non-critical clusters with delayed antibody responses exhibit sustained IFN signatures, which negatively correlate with contemporaneous RBD-specific IgG levels and absolute SARS-CoV-2-specific B and CD4+ T cell frequencies. These data suggest that the Interferon paradox previously described in murine LCMV models is operative in COVID-19, with excessive IFN signaling delaying development of adaptive virus-specific immunity.

Aquaporin 3 modulates the risk of death conferred by dehydration in COVID-19 (preprint)

Severe COVID-19 has been associated with dehydration. Recently, a genetic variant near the aquaporin 3 (AQP3) water channel was associated with severe COVID-19 (rs60840586:G, Odds Ratio: 1.07, P=2.5*10-9). We show that dehydration is associated COVID-19 mortality (OR = 2.06 [95% CI = 1.62-2.65], P = 9.13*10-9), and is modulated by interaction with rs60840586:G genotype (OR = 1.95 [95% CI = 1.22-3.28], P = 0.0075).

Central nervous system biomarkers GFAp and NfL associate with post-acute cognitive impairment and fatigue following critical COVID-19 (preprint)

Background A high proportion of patients with coronavirus disease 2019 (COVID-19) experience post-acute COVID-19, including neuropsychiatric symptoms. Objective signs of central nervous system (CNS) damage can be investigated using CNS biomarkers such as glial fibrillary acidic protein (GFAp), neurofilament light chain (NfL) and total tau (t-tau). We have examined whether CNS biomarkers can predict fatigue and cognitive impairment 3–6 months after discharge from the intensive care unit (ICU) in critically ill COVID-19 patients.Methods Fifty-seven COVID-19 patients admitted to the ICU were included with analysis of CNS biomarkers in blood at the ICU and at follow up. Cognitive dysfunction and fatigue were assessed with the Montreal Cognitive Assessment (MoCA) and the Multidimensional Fatigue inventory (MFI-20).Results Elevated GFAp is associated to the development of mild cognitive dysfunction at follow-up (p = 0.01), especially in women (p = 0.005). Patients experiencing different dimensions of fatigue at follow-up had significantly lower GFAp, specifically in general fatigue (p = 0.009), physical fatigue (p = 0.004), mental fatigue (p = 0.001), and reduced motivation (p = 0.001). Women showed a more pronounced decrease in GFAp compared to men, except for mental fatigue where men showed a more pronounced GFAp decrease compared to women. NfL was lower in patients experiencing reduced motivation (p = 0.004).Conclusion Our findings suggest that GFAp and NfL are associated with neuropsychiatric outcome after critical COVID-19.Trial registration: The study was registered à priori (clinicaltrials.gov: NCT04316884 registered on 2020-03-13 and NCT04474249 registered on 2020-06-29).

Proteome-wide Mendelian randomization implicates nephronectin as an actionable mediator of the effect of obesity on COVID-19 severity (preprint)

Obesity is a major risk factor for COVID-19 severity; however, the underlying mechanism is not fully understood. Considering that obesity influences the human plasma proteome, we sought to identify circulating proteins mediating the effects of obesity on COVID-19 severity. We first screened 4,907 plasma proteins to identify proteins influenced by body mass index (BMI) using Mendelian randomization (MR). This yielded 1,216 proteins, whose effects on COVID-19 severity were assessed, again using MR. This two-step approach identified nephronectin (NPNT), for which a one standard deviation increase was associated with severe COVID-19 (odds ratio = 1.71, 95% CI: 1.45-2.02, P = 1.63 x 10-10). Colocalization analyses indicated that an NPNT splice isoform drove this effect. Overall, NPNT mediates 3.7% of the total effect of BMI on severe COVID-19. Finally, we found that decreasing body fat mass and increasing fat-free mass can lower NPNT levels and thus may improve COVID-19 outcomes. These findings provide actionable insights into how obesity influences COVID-19 severity.

A global systematic analysis of the occurrence, severity, and recovery pattern of long COVID in 2020 and 2021 (preprint)

ImportanceWhile much of the attention on the COVID-19 pandemic was directed at the daily counts of cases and those with serious disease overwhelming health services, increasingly, reports have appeared of people who experience debilitating symptoms after the initial infection. This is popularly known as long COVID. ObjectiveTo estimate by country and territory of the number of patients affected by long COVID in 2020 and 2021, the severity of their symptoms and expected pattern of recovery DesignWe jointly analyzed ten ongoing cohort studies in ten countries for the occurrence of three major symptom clusters of long COVID among representative COVID cases. The defining symptoms of the three clusters (fatigue, cognitive problems, and shortness of breath) are explicitly mentioned in the WHO clinical case definition. For incidence of long COVID, we adopted the minimum duration after infection of three months from the WHO case definition. We pooled data from the contributing studies, two large medical record databases in the United States, and findings from 44 published studies using a Bayesian meta-regression tool. We separately estimated occurrence and pattern of recovery in patients with milder acute infections and those hospitalized. We estimated the incidence and prevalence of long COVID globally and by country in 2020 and 2021 as well as the severity-weighted prevalence using disability weights from the Global Burden of Disease study. ResultsAnalyses are based on detailed information for 1906 community infections and 10526 hospitalized patients from the ten collaborating cohorts, three of which included children. We added published data on 37262 community infections and 9540 hospitalized patients as well as ICD-coded medical record data concerning 1.3 million infections. Globally, in 2020 and 2021, 144.7 million (95% uncertainty interval [UI] 54.8-312.9) people suffered from any of the three symptom clusters of long COVID. This corresponds to 3.69% (1.38-7.96) of all infections. The fatigue, respiratory, and cognitive clusters occurred in 51.0% (16.9-92.4), 60.4% (18.9-89.1), and 35.4% (9.4-75.1) of long COVID cases, respectively. Those with milder acute COVID-19 cases had a quicker estimated recovery (median duration 3.99 months [IQR 3.84-4.20]) than those admitted for the acute infection (median duration 8.84 months [IQR 8.10-9.78]). At twelve months, 15.1% (10.3-21.1) continued to experience long COVID symptoms. Conclusions and relevanceThe occurrence of debilitating ongoing symptoms of COVID-19 is common. Knowing how many people are affected, and for how long, is important to plan for rehabilitative services and support to return to social activities, places of learning, and the workplace when symptoms start to wane. Key PointsO_ST_ABSQuestionC_ST_ABSWhat are the extent and nature of the most common long COVID symptoms by country in 2020 and 2021? FindingsGlobally, 144.7 million people experienced one or more of three symptom clusters (fatigue; cognitive problems; and ongoing respiratory problems) of long COVID three months after infection, in 2020 and 2021. Most cases arose from milder infections. At 12 months after infection, 15.1% of these cases had not yet recovered. MeaningThe substantial number of people with long COVID are in need of rehabilitative care and support to transition back into the workplace or education when symptoms start to wane.

Exome-wide association study to identify rare variants influencing COVID-19 outcomes: Results from the Host Genetics Initiative (preprint)

Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,048 severe disease cases and 571,009 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75-10.05, p=5.41x10-7). These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.

Chest dual energy CT to assess the effects of steroids on lung function in severe COVID-19 patients (preprint)

Background: Steroids have been shown to reduce inflammation, hypoxic pulmonary vasoconstriction (HPV) and lung oedema. Based on evidences from clinical trials, steroids are widely used in severe COVID-19. However, the effect on lung aeration and perfusion in this group of patients are unexplored. Objective: Profiting by dual energy computed tomography (DECT), we investigated whether steroids affect HPV in severe COVID-19 and whether they reduce lung oedema and improve gas distribution. Methods: . Severe COVID-19 patients included in a single-center prospective observational study at the intensive care unit at Uppsala University Hospital who had undergone DECT were enrolled in the current study. Patients’ cohort was divided in two groups depending on the administration of steroids. From each patient’s DECT, 20 inflation maps and 20 perfusion maps, evenly distributed along the cranial-caudal axis, were analyzed. To estimate HPV, perfusion distribution was analyzed in both the whole lung and the hypoinflated areas. Total lung weight, index of lung oedema, was estimated. Results: . Sixty patients were analyzed, whereof 43 received steroids. Patients exposed to steroids showed a better (non-perfused area 10% vs 15%, p Conclusions: . The use of steroids was associated with impaired HPV and reduced lung oedema in severe COVID-19. This is consistent with previous findings in other diseases. Moreover, reduced lung weight and a more homogeneous distribution of gas within the lung were shown in patients treated with steroids.Trial registration: Clinical Trials ID: NCT04316884, Registered March 13, 2020

Loss of Y in leukocytes as a risk factor for critical COVID-19 in men (preprint)

COVID-19 shows an unexplained, strong male bias for severity and mortality. Loss of Y (LOY) in myeloid cells is a risk factor candidate in COVID-19 because of associations with many age-related diseases and its effect on transcription of immune genes. We report the highest levels of LOY in cells that are crucial for the development of severe COVID-19 phenotype, such as low-density neutrophils, granulocytes, and monocytes reaching 46%, 32%, and 29%, respectively, from men with critical COVID-19 (n=139). LOY in sorted subpopulations of leukocytes correlated with increased thrombocyte count, thromboembolic events, invasive mechanical ventilation and a history of vessel disease. In recovered patients, LOY decreased in whole blood and peripheral blood mononuclear cells. Moreover, sc-RNA-seq analysis of CD14+ monocytes from 30 COVID-19 males and 34 controls revealed pervasive transcriptional downregulation in LOY-cells, notably affecting HLA class I and II genes important for antigen presentation. The data support a link between LOY and emergency myelopoiesis as well as the role of LOY in modulation of COVID-19 severity. Our results might also be relevant for other viral infections showing similar male bias.

Limitations of the ARDS criteria during high-flow oxygen or non-invasive ventilation: Evidence from critically ill COVID-19 patients (preprint)

Introduction: The ratio of partial pressure of arterial oxygen to inspired oxygen fraction (PaO2/FIO2) during invasive mechanical ventilation (MV) is used as criteria to grade the severity of respiratory failure in acute respiratory distress syndrome (ARDS). During the SARS-CoV2 pandemic the use of PaO2/FIO2 ratio has been increasingly used in non-invasive respiratory support such as high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV). The grading of hypoxemia in non-invasively ventilated patients is uncertain. The main hypothesis, investigated in this study, was that the PaO2/FIO2 ratio does not change when switching between MV, NIV and HFNC. Methods This was a sub-study of a single-center prospective observational study of patients admitted to the intensive care unit (ICU) at Uppsala University Hospital in Sweden for critical COVID-19. In a steady state condition, the PaO2/FIO2 ratio was recorded before and after any change between two of the studied respiratory support techniques (i.e., HFNC, NIV and MV). Results A total of 148 patients were included in the present analysis. We find that any change in respiratory support from or to HFNC caused a significant change in PaO2/FIO2 ratio (up to 48 mmHg, from HFNC to MV). Changes in respiratory support between NIV and MV did not show consistent change in PaO2/FIO2 ratio. In patients classified as mild to moderate ARDS during MV, the change from HFNC to MV showed a variable increase in PaO2/FIO2 ratio ranging between 52 and 140 mmHg (median of 127 mm Hg). This made prediction of ARDS severity during MV from the apparent ARDS grade during HFNC impossible. Conclusion HFNC is associated with lower PaO2/FIO2 ratio than either NIV or MV in the same patient, while NIV and MV provided similar PaO2/FIO2 and thus ARDS grade by Berlin definition. The large variation of PaO2/FIO2 ratio precludes using ARDS grade as a measure of pulmonary damage during HFNC.

Common, low-frequency, rare, and ultra-rare coding variants contribute to COVID-19 severity. (preprint)

The combined impact of common and rare exonic variants in COVID-19 host genetics is currently insufficiently understood. Here, common and rare variants from whole exome sequencing data of about 4,000 SARS-CoV-2-positive individuals were used to define an interpretable machine learning model for predicting COVID-19 severity. Firstly, variants were converted into separate sets of Boolean features, depending on the absence or the presence of variants in each gene. An ensemble of LASSO logistic regression models was used to identify the most informative Boolean features with respect to the genetic bases of severity. The Boolean features selected by these logistic models were combined into an Integrated PolyGenic Score that offers a synthetic and interpretable index for describing the contribution of host genetics in COVID-19 severity, as demonstrated through testing in several independent cohorts. Selected features belong to ultra-rare, rare, low-frequency, and common variants, including those in linkage disequilibrium with known GWAS loci. Noteworthly, around one quarter of the selected genes are sex-specific. Pathway analysis of the selected genes associated with COVID-19 severity reflected the multi-organ nature of the disease. The proposed model might provide useful information for developing diagnostics and therapeutics, while also being able to guide bedside disease management.

Clinical echocardiography does not indicate cardiac dysfunction in critically ill Covid-19 patients (preprint)

ObjectiveWe aimed to investigate the acute cardiac effects of severe SARS-CoV-2. MethodsThis is an observational study generated from the first 79 patients admitted to Uppsala intensive care due to respiratory failure with SARS-CoV-2 infection. 34 underwent echocardiography of which 25 were included in the study and compared to 44 non-echo patients. Exclusion was based on absence of normofrequent sinus rhythm and mechanical respiratory support. Biomarker analysis was carried out on all patients. ResultsMortality was increased in the echo compared to non-echo group (44 % vs. 16%, p<0.05). Right sided dimensions and functional parameters were not affected. Tricuspid regurgitation velocity indicated how increased pulmonary artery pressure was associated with mortality (survivors (n=5): 2.51 {+/-} 0.01 m/s vs. non-survivors (n=5): 3.06 {+/-} 0.11 m/s, p<0.05). Cardiac markers and D-dimer correlated to initiation of echocardiography (hs-TnI (ng/L): echo (n=23): 133 {+/-} 45 vs. non-echo (n=41): 81.3 {+/-} 45, p<0.01; NTproBNP (ng/L): echo (n=25): 2959 {+/-} 573 vs. non-echo (n=42): 1641 {+/-} 420, p<0.001; D-dimer (mg/L): echo (n=25): 16.1 {+/-} 3.7 vs. non-echo (n=43: 6.1 {+/-} 1.5, p<0.01) and mortality (hs-TnI (ng/L): survivors (n=48): 59.1 {+/-} 21 vs. non-survivors (n=17): 211 {+/-} 105, p<0.0001; NT-proBNP (ng/L): survivors (n=47): 1310 {+/-} 314 vs. non-survivors (n=20): 4065 {+/-} 740, p<0.0001; D-dimer (mg/L): survivors (n=50): 7.2 {+/-} 1.5 vs. non-survivors (n=18): 17.1 {+/-} 4.8, p<0.01). All intervals refer to standard error of the mean. Tricuspid regurgitation velocity was correlated with troponin I (r=0.93, r2=0.74, p<0.001, n=10). ConclusionsThese results suggest that there is no clear negative effect on cardiac function in critical SARS-CoV-2. There are indications that pulmonary pressure elevation carries a negative predictive outcome suggesting pulmonary disease as the driver of mortality. Cardiac biomarkers as well as D-dimer carry predictive value. Trial registration numberPatients were included in "Clinical trials NCT04316884" Article summaryO_ST_ABSStrength and limitations of this studyC_ST_ABS- The patient body is recruited from all patients admitted to ICU in need of mechanical respiratory support independent of background which makes it relevant to clinical practice. - The echocardiographic image acquisition was carried out by hospital assigned agents on clinical indication, which makes the results applicable in a clinical setting. - Since the image acquisition was carried out on a clinical indication, the results may be skewed towards the false positive if applied to all Covid19 patients.

ECG with Prior Myocardial Infarction Pattern or acute ST-T Pathology is Associated with Death in Critically Ill COVID-19 Patients (preprint)

Background: We investigated the prevalence of ECG abnormalities and their association with mortality, organ dysfunction and cardiac biomarkers in a cohort of COVID-19 patients admitted to the intensive care unit (ICU).Methods: This cohort study included patients with COVID-19 admitted to the ICU of a tertiary hospital in Sweden. ECG, clinical data and laboratory findings during ICU stay were extracted from medical records and ECGs obtained near ICU admission were reviewed by two independent physicians. Results: Eighty patients had an acceptable ECG near ICU-admission. In the entire cohort 30-day mortality was 28%. Compared to patients with normal ECG, among whom 30-day mortality was 16%, patients with ECG fulfilling criteria for prior myocardial infarction had higher mortality, 63%, odds ratio (OR) 9.61 (95% confidence interval (CI) 2.02-55.6) adjusted for Simplified Acute Physiology Score 3 and patients with ST-T abnormalities had 50% mortality and OR 6.05 (95% CI 1.82-21.3) in univariate analysis. Both prior myocardial infarction pattern and ST-T pathology were associated with need for vasoactive treatment and higher peak plasma levels of troponin-I, NT-pro-BNP (N-terminal pro-Brain Natriuretic Peptide), and lactate during ICU stay compared to patients with normal ECG. Conclusion: ECG with prior myocardial infarction pattern or acute ST-T pathology at ICU admission is associated with death, need for vasoactive treatment and higher levels of biomarkers of cardiac damage and strain in severely ill COVID-19 patients, and should alert clinicians to a poor prognosis.Trial registration: ClinicalTrials ID: NCT04316884. Registered 20 March 2020, https://clinicaltrials.gov/ct2/show/NCT04316884. 

COVID-19 Antibody Testing of Patients Admitted to the ICU by a Novel, Point-of-Care Assay, and the Relationship to Survival (preprint)

Diagnosing persons infected by COVID-19 is key to the control of the pandemic. It has, however, become increasingly important to identify those who have had the infection by measurement of circulating antibodies against Sars-COV-2 of the IgM and IgG type. In this report we show the development of a rapid and sensitive point-of-care assay for the measurement of IgG antibodies against the two spike proteins, S1 and S2, of the Sars-COV-2 virus.MethodThe AgPlus electrochemical technology was applied and the S1 and S2 proteins were biotinylated and immobilized onto streptavidin coated magnetic particles as the capture component of the assay. The IgG antibodies bound to the particles were detected by anti-human IgG and the signal expressed as nC (nano Coulomb). Assay time was <10 min.ResultsPlasma (n=211) from 117 SARS-Cov-2 PCR positive patients and from 78 persons with samples taken before the COVID-19 pandemic were analysed. The sensitivity and specificity of the assay were 91.9% and 100%, respectively. The assay was highly correlated to a predicate and FDA-approved IgG antibody ELISA (r=0.81). The IgG response was significantly lower in patients who died during their ICU stay.ConclusionsA poor IgG response after a COVID-19 infection is a serious risk factor as to death. A sensitive, rapid and accurate IgG antibody POC assay should be useful in the daily management and evaluation of COVID-19 infected patients.

Elevated Angiopoietin-2 inhibits thrombomodulin-mediated anticoagulation in critically ill COVID-19 patients (preprint)

Several studies suggest that hypercoagulation and endothelial dysfunction play central roles in severe forms of COVID-19. Here, we hypothesized that the high levels of the inflammatory cytokine Angiopoietin-2 (ANGPT2) reported in hospitalized COVID-19 patients might promote hypercoagulation through ANGPT2 binding to thrombomodulin with resulting inhibition of thrombin/thrombomodulin-mediated physiological anticoagulation. We therefore investigated plasma samples taken at two timepoints from 20 critically ill COVID-19 patients in intensive care regarding ANGPT2 levels and coagulation markers in comparison with 20 healthy blood donors. We found that ANGPT2 levels were increased in the COVID-19 patients in correlation with disease severity, hypercoagulation, and mortality. To test causality, we administered ANGPT2 to wildtype mice and found that it shortened bleeding time in a tail injury model. In further support of a role for ANGPT2 in physiological coagulation, bleeding time was increased in endothelial-specific Angpt2 knockout mice. Using in vitro assays, we found that ANGPT2 inhibited thrombomodulin-mediated anticoagulation and protein C activation in human donor plasma. Our data reveal a novel mechanism for ANGPT2 in hypercoagulation and suggest that Angiopoietin-2 inhibition may be tested in the treatment of hypercoagulation in severe COVID-19, as well as in certain other conditions, including sepsis.

The Impact of Viremia on Organ Failure, Biomarkers and Mortality in a Swedish Cohort of Critically ill COVID-19 Patients (preprint)

BackgroundThe spread of virus via the blood stream has been suggested to contribute to extra pulmonary organ failure in Coronavirus disease 2019 (COVID-19). We assessed SARS-CoV-2 RNAemia (RNAemia) and the association between RNAemia and inflammation, organ failure and mortality in critically ill COVID-19 patients.MethodsIn a tertiary center we included all patients with PCR verified COVID-19 and consent admitted to ICU. SARS-CoV-2 RNA copies above 1000/ml measured by PCR in plasma was defined as RNAemia and used as surrogate for viremia.ResultsOf the 92 patients RNAemia was found in 31 (34%) and RNA in plasma was detected in 63 (58%). Hypertension and corticosteroid treatment was more common in patients with RNAemia . RNAemia levels were higher in patients with RAAS-inhibitor treatment or corticosteroid treatment than those without. Extra-pulmonary organ failure biomarkers and the extent of organ failure were similar in patients with and without RNAemia, but the former group had more renal replacement therapy and higher mortality (26 vs 16%; 35 vs 16%, respectively, p=0.04). RNAemia was not an independent predictor of death at 30 days after adjustment for age. ConclusionSARS-CoV2 RNA copies in plasma is a common finding in ICU patients with COVID-19. Although viremia was not associated with extra pulmonary organ failure it was more common in patients who did not survive to 30 days after ICU admission.Trial registrationClinicalTrials NCT04316884

Circulating Proteins Influencing COVID-19 Susceptibility and Severity: a Mendelian Randomization Study (preprint)

Proteins detectable in peripheral blood may influence COVID-19 susceptibility or severity. However, understanding which circulating proteins are etiologically involved is difficult because their levels may be influenced by COVID-19 itself and also subject to confounding factors. To identify circulating proteins influencing COVID-19 susceptibility and severity we undertook a large-scale two-sample Mendelian randomization (MR) study, since this study design can rapidly scan hundreds of circulating proteins and reduces bias due to confounding and reverse causation. We began by identifying the genetic determinants of 955 circulating proteins in up to 10,708 SARS-CoV-2 uninfected individuals, retaining only single nucleotide polymorphisms near the gene encoded by the circulating protein. We then undertook an MR study to estimate the effect of these proteins on COVID-19 susceptibility and severity using the Host Genetics Initiative. We found that a standard deviation increase in OAS1 levels was associated with reduced COVID-19 death or ventilation (N = 2,972 cases / 284,472 controls; OR = 0.48, P = 7x10-8), COVID-19 hospitalization (N = 6,492 / 1,012,809; OR = 0.60, P = 2x10-7) and COVID-19 susceptibility (N = 17,607 / 1,345,334; OR = 0.81, P = 6x10-5). Results were consistent despite multiple sensitivity analyses probing MR assumptions. OAS1 is an interferon-stimulated gene that promotes viral RNA degradation. Other potentially implicated proteins included IL10RB. Available medicines, such as interferon-beta-1b, increase OAS1 and could be explored for their effect on COVID-19 susceptibility and severity.

Critical Illness Polyneuropathy and Myopathy in COVID-19 Patients: A Prospective Observational Intensive Care Unit Cross-Sectional Cohort Study (preprint)

Background: Several reports on neurological complications associated with SARS-CoV-2 infection have been published. However, systematic description on intensive care unit acquired weakness (ICUAW) are still missing. Methods: The objective was to determine the incidence and characteristics of critical illness polyneuropathy (CIN) and myopathy (CIM) in patients with severe COVID-19. We also aimed to describe the electrophysiological features and their relation to plasma biomarkers for neuronal injury. This was a prospective observational intensive care unit cohort study. All adult patients admitted to the general intensive care unit (ICU) at Uppsala University Hospital, Uppsala, Sweden, between March 13 and June 8, 2020 were screened for inclusion. Patients with PCR confirmed COVID-19 were included. All patients were admitted to intensive care treatment due to severe COVID-19, including intravenous anaesthesia, opioid anaelgesia, neuromuscular blockade and mechanical ventilation. Associations of clinical, electrophysiological (sensory and motor conduction studies and electromyography) and biomarker data [neurofilament light chain (NfL), glial fibrillary acidic protein (GFAp) and tau] were studied between COVID-19 patients who developed CIN/CIM and those who did not. Results: 111 COVID-19 patients were included, 11 (11 males, mean age: 64 years) developed CIN/CIM whereas 100 (74 males, mean age: 61 years) did not (non-CIN/CIM). The CIN/CIM incidence was higher in COVID-19 patients compared to a general ICU-population treated during 2019 (9.9% vs 3.4%). In particular CIN was more frequent in the COVID-19 ICU cohort (50%) compared with the non-COVID-19 ICU cohort (0%, p=0.008). NfL and GFAp levels were higher in the CIN/CIM group both at the early (<9 days) and late time points (>11 days) compared with the non-CIN/CIM group (both p=0.001) and correlated with nerve amplitudes. Conclusions: CIN/CIM, in particular CIN, were more prevalent among COVID-19 patients than an ICU treated control cohort and should be considered in the differential diagnostic workup and the further rehabilitation of COVID-19 patients. COVID-19 patients who later developed ICUAW had significantly higher NfL and GFAp in the early phase of ICU care, which suggests their potential as predictive biomarkers. Trial registration: The study protocol was registered (ClinicalTrialsID:NCT04316884). Mechanisms for Organ Dysfunction in Covid-19 (UMODCOVID19) March 18, 2020.