In an add-on study of the WHO Solidarity trial, Norwegian investigators examined the effect of remdesivir and hydroxychloroquine on the degree of clinical respiratory failure, on SARS-CoV-2 viral load in the oropharynx, and on levels of inflammatory variables in plasma or serum.
The association between pulmonary sequelae and markers of disease severity, as well as pro-fibrotic mediators, were studied in 108 patients 3 months after hospital admission for COVID-19. The COPD assessment test (CAT-score), spirometry, diffusion capacity of the lungs (DLCO), and chest-CT were performed at 23 Norwegian hospitals included in the NOR-SOLIDARITY trial, an open-labelled, randomised clinical trial, investigating the efficacy of remdesivir and hydroxychloroquine (HCQ). Thirty-eight percent had a CAT-score ≥ 10. DLCO was below the lower limit of normal in 29.6%. Ground-glass opacities were present in 39.8% on chest-CT, parenchymal bands were found in 41.7%. At admission, low pO2/FiO2 ratio, ICU treatment, high viral load, and low antibody levels, were predictors of a poorer pulmonary outcome after 3 months. High levels of matrix metalloproteinase (MMP)-9 during hospitalisation and at 3 months were associated with persistent CT-findings. Except for a negative effect of remdesivir on CAT-score, we found no effect of remdesivir or HCQ on long-term pulmonary outcomes. Three months after hospital admission for COVID-19, a high prevalence of respiratory symptoms, reduced DLCO, and persistent CT-findings was observed. Low pO2/FiO2 ratio, ICU-admission, high viral load, low antibody levels, and high levels of MMP-9 were associated with a worse pulmonary outcome.
Background
Although coronavirus disease 2019 (COVID‐19) is primarily a respiratory infection, mounting evidence suggests that the gastrointestinal tract is involved in the disease, with gut barrier dysfunction and gut microbiota alterations being related to disease severity. Whether these alterations persist and are related to long‐term respiratory dysfunction remains unknown.
Methods
Plasma was collected during hospital admission and after 3 months from the NOR‐Solidarity trial (n = 181) and analyzed for markers of gut barrier dysfunction and inflammation. At the 3‐month follow‐up, pulmonary function was assessed by measuring the diffusing capacity of the lungs for carbon monoxide (DLCO). Rectal swabs for gut microbiota analyses were collected (n = 97) and analyzed by sequencing the 16S rRNA gene.
Results
Gut microbiota diversity was reduced in COVID‐19 patients with respiratory dysfunction, defined as DLCO below the lower limit of normal 3 months after hospitalization. These patients also had an altered global gut microbiota composition, with reduced relative abundance of 20 bacterial taxa and increased abundance of five taxa, including Veillonella, potentially linked to fibrosis. During hospitalization, increased plasma levels of lipopolysaccharide‐binding protein (LBP) were strongly associated with respiratory failure, defined as pO2/fiO2 (P/F ratio) <26.6 kPa. LBP levels remained elevated during and after hospitalization and were associated with low‐grade inflammation and respiratory dysfunction after 3 months.
Conclusion
Respiratory dysfunction after COVID‐19 is associated with altered gut microbiota and persistently elevated LBP levels. Our results should be regarded as hypothesis generating, pointing to a potential gut–lung axis that should be further investigated in relation to long‐term pulmonary dysfunction and long COVID.
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