ABSTRACT
BackgroundA significant proportion of patients experience prolonged pulmonary, cardiocirculatory or neuropsychiatric symptoms after Coronavirus disease 2019 (COVID-19), termed post-acute sequelae of COVID (PASC). Lung manifestations of PASC include cough, dyspnea on exertion and persistent radiologic abnormalities and have been linked to viral persistence, ongoing inflammation and immune dysregulation. So far, there is limited data on lung histopathology and tissue-based immune cell subtyping in PASC. Methods51 unvaccinated patients (median age, 40 years; 43% female) with a median of 17 weeks (range, 2-55 weeks) after mild SARS-CoV-2 infection (without hospitalization) underwent full clinical evaluation including high-resolution computed tomography (HR-CT) and transbronchial biopsy. We used RT-PCR/FISH and immunohistochemistry (nucleocapsid/spike/CD3/CD4/CD8) for residual SARS-CoV-2 detection and T lymphocyte subtyping, respectively. We assessed interstitial fibrosis and macrophage profiles by transmission electron microscopy (TEM) and immunofluorescence multiplex staining, while cytokine profiling in bronchoalveolar lavage (BAL) fluid was performed by legendplex immunoassay. ResultsDyspnea on exertion was the leading symptom of pulmonary PASC in our cohort. In 16% and 42.9% of patients, FEV1 and MEF50 were [≤] 80% and 35.3% showed low attenuation volume (LAV) in >5% of lung area, in line with airflow obstruction. There was a significant correlation between oxygen pulse and time since COVID (p=0.009). Histopathologically, PASC manifested as organizing pneumonia (OP), fibrinous alveolitis and increased CD4+ T cell infiltrate predominantly around airways (bronchiolitis), while the residual virus components were detectable in only a single PASC patient (2%). T cell infiltrates around small airways were inversely correlated with time since COVID, however, this trend failed to reach statistical significance. We identified discrete interstitial fibrosis and a pro-fibrotic macrophage subtype (CD68/CD163/S100A9) as well as significantly elevated interleukin 1{beta} in BAL fluid from PASC patients (p=0.01), but H-scores for fibrotic macrophage population did not correlate with severity of clinical symptoms or T cell infiltration. InterpretationWe show decreased FEV1/MEF50 and increased LAV in line with obstructive lung disease due to CD4+ T cell-predominant bronchiolitis as well as evidence of pro-fibrotic signaling in a subset of unvaccinated PASC patients. Since our results point towards self-limiting inflammation of small airways without detectable viral reservoirs, it remains unclear whether pulmonary symptoms in PASC are SARS-CoV-2-specific or represent a general response to viral infection. Still, evidence of pro-fibrotic signaling should warrant clincal follow-up and further research into possible long-time fibrotic remodeling in PASC patients. Key pointsO_LIDyspnea on exertion is the leading clinical manifestation of PASC in the lung C_LIO_LIa minority of pts have significantly impaired lung function (FVC/TLC[≤]80% or DLCO[≤]70%) in spiroergometry and/or radiologic abnormalities, oxygen pulse seems to normalize over time O_LI16% and 42.9% of pts have FEV1 and MEF50[≤]80% and 35.3% have LAV>5% of lung area, in line with airflow obstruction due to bronchiolitis C_LI C_LIO_LIResidual virus was not detectable in the lung tissue of all but one PASC patient (2%) C_LIO_LIHistologically, PASC may manifest as T cell-mediated bronchiolitis, OP and fibrinous alveolitis C_LIO_LIThere is evidence of fibrotic remodeling (ultrastructural interstitial fibrosis, pro-fibrotic macrophage subpopulation, pro-fibrotic cytokine IL-1{beta} in BAL) but this did not correlate with the degree of T cell infiltrate/bronchiolitis C_LI
ABSTRACT
BackgroundRecovery from coronavirus disease 2019 (COVID-19) can be impaired by the persistence of symptoms or new-onset health complications, commonly referred to as Long COVID. In a subset of patients, Long COVID is associated with immune system perturbations of unknown etiology, which could be related to compromised immunoregulatory mechanisms. ObjectiveThe aim of this scoping review was to investigate if regulatory T cell (Treg) dysregulation is observable beyond the acute illness and if it might be involved in Long COVID immunopathology. DesignA systematic search of studies investigating Tregs during COVID-19 convalescence was conducted on MEDLINE (via Pubmed) and Web of Science. ResultsThe literature search yielded 17 relevant studies, of which three included a distinct cohort of patients with Long COVID. The reviewed studies suggest that the Treg population of COVID-19 patients can reconstitute quantitatively and functionally during recovery. However, the comparison between recovered and seronegative controls revealed that an infection-induced dysregulation of the Treg compartment can be sustained for at least several months. The small number of studies investigating Tregs in Long COVID allowed no firm conclusions to be drawn about their involvement in the syndromes etiology. Yet, even almost one year post-infection Long COVID patients exhibit significantly altered proportions of Tregs within the CD4+ T cell population. ConclusionsPersistent alterations in cell frequency in Long COVID patients indicate that Treg dysregulation might be linked to immune system-associated sequelae. Future studies should aim to address the association of Treg adaptations with different symptom clusters and blood parameters beyond the sole quantification of cell frequencies while adhering to consensualized phenotyping strategies.
ABSTRACT
BackgroundAcute respiratory distress syndrome (ARDS) is the major cause of death in coronavirus disease 2019 (COVID-19). Multiple autopsy-based reports of COVID-19 lung pathology describe diffuse alveolar damage (DAD), organizing pneumonia (OP) and fibrotic change, but data on early pathological changes as well as during progression of the disease are rare. Research questionComparison of histopathological and ultrastructural findings in paired transbronchial biopsies (TBBs) and autopsy material from three patients with confirmed SARS-CoV-2-infection. MethodsWe prospectively enrolled 3 patients with confirmed SARS-CoV-2 infection. Full clinical evaluation was performed including high-resolution computed tomography (HR-CT). We took TBBs at different time points during the disease and autopsy tissue samples after the patients death. ResultsSARS-CoV-2 was detected by RT-PCR and/or FISH in all TBBs. Lung histology revealed pneumocyte hyperplasia and capillary congestion in one patient who died short after hospital admission with detectable virus in 1/2 autopsy samples from the lung. SARS-CoV-2 was detected in 2/2 autopsy samples from a patient with a fulminant course of the disease and very short latency between biopsy and autopsy, both showing widespread DAD. In a third patient with a prolonged course, i.e. five weeks of ICU treatment with ECMO, autopsy samples showed extensive interstitial fibrosis without detectable virus by RT-PCR and/or FISH. InterpretationWe report the course of COVID-19 in paired TBB and autopsy samples from three patients at an early stage, in rapidly progressive and in a prolonged disease course. Our findings illustrate vascular, organizing and fibrotic patterns of COVID-19-induced lung injury and suggest an early spread of SARS-CoV-2 from the upper airways to the lung periphery with diminishing viral load during disease.
ABSTRACT
Artificial gravity protocols are used to improve g-tolerance of aviators and discussed as countermeasure during prolonged space flight. Little is known about the impact of artificial gravity on the red blood cells (RBC). The purpose of the study was to test how artificial gravity affects RBC deformability and aggregation, which are important determinants of microcirculation. Nine male subjects were exposed to two hypergravity protocols using a short arm human centrifuge: a continuous (CONT) protocol with constant +2Gz for 30min and an intermittent (INTER) protocol with repeated intervals of +2Gz and rest. Blood was sampled pre and post interventions to measure basal blood parameters, RBC nitrite, RBC deformability, aggregation, and to determine the shear rate balancing aggregation and disaggregation (γ at dIsc min). To test for orthostasis effects, five male subjects were asked to stay for 46min, corresponding to the length of the centrifuge protocols, with blood sampling pre and post intervention. Artificial gravity programs did not affect basal blood parameters or RBC nitrite levels; a marker for RBC deformability influencing nitric oxide. The INTER program did not affect any of the tested parameters. The CONT program did not remarkably affect RBC deformability or γ at dIsc min but significantly aggravated aggregation. Orthostasis effects were thus excluded. The results indicate that continuous artificial gravity, especially with higher g-forces applied, may negatively affect the RBC system and that for a prolonged space flight intermittent but not continuous artificial gravity might represent an appropriate countermeasure.
Subject(s)
Erythrocyte Aggregation/physiology , Erythrocyte Deformability/physiology , Gravity, Altered/adverse effects , Adult , Humans , Male , Nitric Oxide/metabolism , Nitrites/metabolismABSTRACT
The present article summarizes recent data presented at the Exercise and Hemorheology symposium during the 15th Conference of the European Society for Clinical Hemorheology and Microcirculation (June 28-July 1, Pontresina, Switzerland, 2009). The review starts with several unresolved paradoxes in exercise hemorheology. Then, we focus on the potential hemorheological and immunological mechanisms involved in the adverse events sometimes reported in exercising sickle cell trait carriers, and the role of habitual physical activity. In a fourth part, new results on the effects of acute hypoxia on blood rheology are presented. Finally, we will discuss recent experimental evidences on the role of exercise on the regulation of nitric oxide synthesizing mechanisms in red blood cell.
Subject(s)
Exercise/physiology , Hemorheology/physiology , Humans , Sickle Cell Trait/bloodABSTRACT
<p><b>AIM</b>Nitric oxide (NO)-mediated smooth muscle relaxation causes penile erections. The endothelial NO synthase (eNOS) coenzyme tetrahydrobiopterin (BH4) converts eNOS-mediated catalytic activity from oxygen radical to NO production, improving endothelial function and vascular smooth muscle relaxation.</p><p><b>METHODS</b>Using quantitative immunohistochemistry, 8-isoprostane and nitrotyrosine concentrations were compared in cavernosal tissue from 17 potent and 7 impotent men, and the effect of single oral doses of BH4 on penile rigidity and tumescence was investigated. The pharmacodynamic effect of single oral doses of BH4 on penile rigidity and tumescence was investigated in a randomized, placebo-controlled, double-blind cross-over fashion in 18 patients with erectile dysfunction (ED) while receiving visual sexual stimulation.</p><p><b>RESULTS</b>8-Isoprostane content in endothelium and smooth muscle was significantly higher in impotent patient samples; the level of nitrotyrosine was unchanged in ED patients. Relative to placebo, a single dose of 200 mg BH4 led to a mean increase in duration of > 60% penile rigidity (33.5 min [95% confidence interval (CI): 13.1-49.3] at base and 29.4 min [95% CI: 8.9-42.2] at tip). A 500-mg dose increased the relative duration of > 60% penile rigidity by 36.1 min (95% CI: 16.3-51.8) at the base and 33.7 min (95% CI: 11.4-43.9) at the tip. Treatments were well tolerated.</p><p><b>CONCLUSION</b>BH4 treatment is suggested to switch eNOS catalytic activity from super-oxide to NO formation, leading to a reduced formation of free radical reaction product 8-isoprostane without alteration of nitrotyrosine. The observed results make BH4 a suitable candidate as an ED treatment through reconstitution of altered catalytic activity of the eNOS.</p>
Subject(s)
Adolescent , Adult , Aged , Humans , Male , Middle Aged , Biopterins , Therapeutic Uses , Cross-Over Studies , Dinoprost , Double-Blind Method , Erectile Dysfunction , Drug Therapy , Immunohistochemistry , In Vitro Techniques , Muscle, Smooth, Vascular , Chemistry , Nitric Oxide , Physiology , Penile Erection , Physiology , Penis , Chemistry , TyrosineABSTRACT
<p><b>OBJECTIVE</b>To study the significance by analyzing the expression of angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2) in the tissues of squamous cell carcinoma (SCC) of the head and neck areas and in normal mucosa tissues.</p><p><b>METHODS</b>The expression of Ang-1 and Ang-2 in 45 tumor samples and 7 normal mucosa tissues were determined by the immunohistochemical method with avidin-biotin-peroxidase complex technique. The results were scored by two independent observers and analyzed statistically.</p><p><b>RESULTS</b>The positive expression of Ang-1 and Ang-2 existed in the endothelial cells, epithelial cells and also in SCC cells. The positive expression rates of Ang-1 in tumor samples was 78% in the endothelial cells, and 87% in SCC cells. The positive expression rates of Ang-2 in tumor samples was 69% in the endothelial cells, and 76% in SCC cells. The scores of positive expression of Ang-1 and Ang-2 were higher in endothelial cells and in SCC cells of tumor tissues than that of normal mucosa tissues (rank sum test, P < 0. 05). There was positive correlation between the expression of Ang-1 and Ang-2 in the endothelial cells and also in SCC cells (Chi-square test with contingency table, P < 0.05). Ang-1 expression in endothelial cells of tumor tissues was higher in clinical stage III-IV than that in clinical stage I-II (rank sum test, P < 0.05). Ang-2 expression in both endothelial cells and SCC cells, were higher in clinical stage II-IV than that in clinical stage I-II (rank sum test, P < 0.05). There was no statistical significance for degrees of Ang-1 and Ang-2 expression in different histological grades (P > 0.05).</p><p><b>CONCLUSIONS</b>The expressions of Ang-1 and Ang-2 in advanced SCC were remarkable. Ang-1 and Ang-2 may play a critical role during the progress of SCC of head and neck areas.</p>
