Clathrin-Mediated Albumin Clearance in Alveolar Epithelial Cells of Murine Precision-Cut Lung Slices.

A hallmark of acute respiratory distress syndrome (ARDS) is an accumulation of protein-rich alveolar edema that impairs gas exchange and leads to worse outcomes. Thus, understanding the mechanisms of alveolar albumin clearance is of high clinical relevance. Here, we investigated the mechanisms of the cellular albumin uptake in a three-dimensional culture of precision-cut lung slices (PCLS). We found that up to 60% of PCLS cells incorporated labeled albumin in a time- and concentration-dependent manner, whereas virtually no uptake of labeled dextran was observed. Of note, at a low temperature (4 °C), saturating albumin receptors with unlabeled albumin and an inhibition of clathrin-mediated endocytosis markedly decreased the endocytic uptake of the labeled protein, implicating a receptor-driven internalization process. Importantly, uptake rates of albumin were comparable in alveolar epithelial type I (ATI) and type II (ATII) cells, as assessed in PCLS from a SftpcCreERT2/+: tdTomatoflox/flox mouse strain (defined as EpCAM+CD31-CD45-tdTomatoSPC-T1α+ for ATI and EpCAM+CD31-CD45-tdTomatoSPC+T1α- for ATII cells). Once internalized, albumin was found in the early and recycling endosomes of the alveolar epithelium as well as in endothelial, mesenchymal, and hematopoietic cell populations, which might indicate transcytosis of the protein. In summary, we characterize albumin uptake in alveolar epithelial cells in the complex setting of PCLS. These findings may open new possibilities for pulmonary drug delivery that may improve the outcomes for patients with respiratory failure.

Long-term comprehensive cardiopulmonary phenotyping of COVID-19.

BACKGROUND: Persistent symptoms after initial COVID-19 infection are common and are frequently referred to by the umbrella terms "post-COVID syndrome" and "long COVID". The sheer number of affected patients pose an increasing challenge to healthcare systems worldwide. To date, our understanding of the pathophysiology of the post-COVID syndrome remains poor and the extent to which persistent cardiopulmonary abnormalities contribute to the symptom complex is unclear. We sought to determine the presence and impact of cardiopulmonary sequelae after COVID-19 in longitudinal assessment. METHODS: We report on 71 patients who underwent comprehensive, longitudinal testing in regular intervals for up to 12 months after their initial COVID-19 diagnosis. Testing included pulmonary function testing, cardiopulmonary exercise testing, dedicated left and right heart echocardiography, lung ultrasonography, and cardiac MRI. RESULTS: Our results demonstrate that subjective quality of life after COVID-19 (EQ-5D visual acuity scale, VAS, 67.4 for patients treated as outpatient, 79.2 for patients admitted to the general floor, 71.8 for patients treated in an ICU) is not related to the severity of the initial infection. Maximal exercise capacity is also reduced (VO2max 79% predicted, SD ± 19%); however, this is driven in large parts by patients who had initially required ICU-level of care. The degree of objective reduction in exertion did not correlate with quality of life scores. Pulmonary function testing revealed mild and persistent reduction in DLCO over the first 12 months without significant restrictive or obstructive lung disease. Left and right heart function was intact with good RV function and intact RV/PA coupling, imaging findings suggestive of myocarditis were uncommon (7% of patients). CONCLUSION: A reduction in exercise capacity after COVID-19 is common, but is most prominent in patients previously treated in the ICU and more likely related to deconditioning or fatigue than to cardiopulmonary impairment. Subjective quality of life scores are independent of the severity of initial infection and do not correlate with objective measures of cardiopulmonary function. In our cohort, persistent cardiopulmonary impairment after COVID-19 was uncommon. The post-COVID syndrome is unlikely to be the result of cardiopulmonary sequalae and may reflect a post-ICU syndrome in some. Trial registration Registered on clinicaltrials.gov (NCT04442789), Date: June 23, 2020.

Physical Activity and Mental Health of Patients with Pulmonary Hypertension during the COVID-19 Pandemic.

The aim of the study was to analyze the effect of personal restrictions on physical activity, mental health, stress experience, resilience, and sleep quality in patients with pulmonary hypertension (PH) during the "lockdown" period of the COVID-19 pandemic. In total, 112 PH patients and 52 age-matched healthy control subjects completed a questionnaire on the topics of physical activity, mental health, resilience, and sleep quality. PH patients had significantly lower physical activity, mental health, and sleep quality compared to age-matched healthy controls. Physical activity positively correlated with mental health and sleep quality in the PH group. Mental wellbeing and life satisfaction could be predicted by total physical activity, sleep, stress level, and resilience. PH patients appeared as an especially vulnerable group, demanding interventions to promote an active lifestyle and protect mental health in these patients. This could be helpful in counseling on how to carry out physical activity while maintaining infection control.

Extracorporeal Carbon Dioxide Removal Using a Renal Replacement Therapy Platform to Enhance Lung-Protective Ventilation in Hypercapnic Patients With Coronavirus Disease 2019-Associated Acute Respiratory Distress Syndrome.

Coronavirus disease 2019 (COVID-19)-associated acute respiratory distress syndrome (ARDS) is associated with high mortality. Lung-protective ventilation is the current standard of care in patients with ARDS, but it might lead to hypercapnia, which is independently associated with worse outcomes. Extracorporeal carbon dioxide removal (ECCO2R) has been proposed as an adjuvant therapy to avoid progression of clinical severity and limit further ventilator-induced lung injury, but its use in COVID-19 has not been described yet. Acute kidney injury requiring renal replacement therapy (RRT) is common among critically ill COVID-19 patients. In centers with available dialysis, low-flow ECCO2R (<500 mL/min) using RRT platforms could be carried out by dialysis specialists and might be an option to efficiently allocate resources during the COVID-19 pandemic for patients with hypercapnia as the main indication. Here, we report the feasibility, safety, and efficacy of ECCO2R using an RRT platform to provide either standalone ECCO2R or ECCO2R combined with RRT in four hypercapnic patients with moderate ARDS. A randomized clinical trial is required to assess the overall benefit and harm. Clinical Trial Registration: ClinicalTrials.gov. Unique identifier: NCT04351906.

Immunoglobulin deficiency as an indicator of disease severity in patients with COVID-19.

Despite the pandemic status of COVID-19, there is limited information about host risk factors and treatment beyond supportive care. Immunoglobulin G (IgG) could be a potential treatment target. Our aim was to determine the incidence of IgG deficiency and associated risk factors in a cohort of 62 critically ill patients with COVID-19 admitted to two German ICUs (72.6% male, median age: 61 yr). Thirteen (21.0%) of the patients displayed IgG deficiency (IgG < 7 g/L) at baseline (predominant for the IgG1, IgG2, and IgG4 subclasses). Patients who were IgG-deficient had worse measures of clinical disease severity than those with normal IgG levels (shorter duration from disease onset to ICU admission, lower ratio of [Formula: see text] to [Formula: see text], higher Sequential Organ Failure Assessment score, and higher levels of ferritin, neutrophil-to-lymphocyte ratio, and serum creatinine). Patients who were IgG-deficient were also more likely to have sustained lower levels of lymphocyte counts and higher levels of ferritin throughout the hospital stay. Furthermore, patients who were IgG-deficient compared with those with normal IgG levels displayed higher rates of acute kidney injury (76.9% vs. 26.5%; P = 0.001) and death (46.2% vs. 14.3%; P = 0.012), longer ICU [28 (6-48) vs. 12 (3-18) days; P = 0.012] and hospital length of stay [30 (22-50) vs. 18 (9-24) days; P = 0.004]. Univariable logistic regression showed increasing odds of 90-day overall mortality associated with IgG-deficiency (odds ratio 5.14, 95% confidence interval 1.3-19.9; P = 0.018). IgG deficiency might be common in patients with COVID-19 who are critically ill, and warrants investigation as both a marker of disease severity as well as a potential therapeutic target.

Severe organising pneumonia following COVID-19.

Various forms of diffuse parenchymal lung disease have been proposed as potential consequences of severe COVID­19. We describe the clinical, radiological and histological findings of patients with COVID­19-associated acute respiratory distress syndrome who later developed severe organising pneumonia including longitudinal follow-up. Our findings may have important implications for the therapeutic modalities in the late-phase of severe COVID­19 and might partially explain why a subgroup of COVID­19 patients benefits from systemic corticosteroids.

Impact of SARS-CoV-2 pandemic on pulmonary hypertension out-patient clinics in Germany: a multi-centre study.

Pulmonary hypertension is frequently underdiagnosed, and referral is delayed with subsequent impact on outcomes. During the SARS-CoV-2 pandemic, restrictions on daily life and changes in hospitals' daily routine care were introduced in Germany. This multi-centre study provides evidence for a negative influence of these restrictions on patient care in pulmonary hypertension expert referral centres.