Prognostic value of serum Krebs von den Lungen-6 (KL-6) levels in COVID-19 pneumonia.

BACKGROUND AND OBJECTIVES: Krebs von den Lungen-6 (KL-6), expressed by damaged type II pneumocytes, is useful in the diagnosis and severity assessment of many diffuse interstitial lung diseases. The objective of our study was to determine the prognostic value of the initial KL-6 plasma level in COVID-19 pneumonia. METHODS: All patients hospitalized for a suspected COVID-19 pneumonia between March and May 2020 in our Chest department of a French university hospital were included. KL-6 serum concentrations were measured within 72 h of diagnostic suspicion by chemiluminescence enzyme immunoassay Survival analysis was performed using a Cox regression and modeled by a Kaplan-Meier curve. RESULTS: Sixty-six COVID-19 patients (average age = 64 ± 14 years, 71.2 % males) with KL-6 serum measurement were included. Median KL-6 serum concentration was 409 ± 312 U/mL. KL-6 was significantly higher in men (p = 0.003), elders (p = 0.0001) and in patients with greater Charlson's score (p = 0.002). Higher KL-6 concentration was significantly associated with in-hospital mortality (HR: 8.66; 95 % CI:1.1-69.2, p = 0.014), radiological extension of lesions on chest CT scan (p = 0.004) and higher WHO severity score (p = 0.042), but not with admission in intensive care unit. In 9 (14 %) non-surviving COVID-19 patients, KL-6 serum concentration increased whereas it remained stable or decreased in survivors. At 3 months follow-up (n = 48), DLCO was negatively correlated with the initial KL-6 value (r = 0.47, p = 0.001), while FVC, FEV1 and MRC score were not. CONCLUSION: Initial KL-6 serum concentration is significantly associated with in-hospital mortality, unfavorable outcome, and persistent impairment of DLCO at 3 months. Initial KL-6 plasma determination appears as a prognostic biomarker in COVID-19 pneumonia.

Cell and cytokine analyses from bronchoalveolar lavage in non-critical COVID-19 pneumonia.

Cell and cytokine analyses from bronchoalveolar lavage (BAL) in non-critically ill patients with COVID-19 pneumonia are poorly described. This study focused on patients hospitalized in the non-intensive care unit for either suspected COVID-19 pneumonia or persistent respiratory symptoms following proven COVID-19 pneumonia. Overall, 54 patients who underwent BAL between April 2020 and February 2021 for suspected or follow-up of proven COVID-19 pneumonia were included. Based on SARS-CoV-2 polymerase chain reaction test results and clinical follow-up, three pulmonary disease groups were defined: non-COVID-19 (n = 20), acute COVID-19 (n = 13), and post-COVID-19 (n = 24) pneumonia patients. Cytological and cytokine analyses were performed on BAL fluid (IL-1ß, IL-6, IL-8, IL-10, TNF-α, IFN-γ, HGF, and TGF-ß), with investigators blinded to the patient groups. Lymphocytic alveolitis with plasmocytes was observed in acute COVID-19 pneumonia, returning to normal post-COVID-19. The highest cytokine levels were observed in COVID-19 patients, with significantly increased IFN-γ, IL-10, and HGF levels compared to non-COVID-19 patients, while significantly decreased IL-6, IL-8, IL-10, IFN-γ, TNF-α, and HGF levels were noted in post-COVID-19 patients. In COVID-19 patients, correlations between IL-10, TNF-α and IFN-γ concentrations were found. Lymphocytic alveolitis with plasmacytosis was found in non-critical COVID-19 pneumonia This alveolitis is associated with the presence of IL-6, IL-8, IL-10, TNF-α, IFN-γ and HGF. Alveolitis and cytokines levels decreased in post-COVID-19 pneumonia.

Sleep Apnea in Idiopathic Pulmonary Fibrosis: A Molecular Investigation in an Experimental Model of Fibrosis and Intermittent Hypoxia.

BACKGROUND: High prevalence of obstructive sleep apnea (OSA) is reported in incident and prevalent forms of idiopathic pulmonary fibrosis (IPF). We previously reported that Intermittent Hypoxia (IH), the major pathogenic element of OSA, worsens experimental lung fibrosis. Our objective was to investigate the molecular mechanisms involved. METHODS: Impact of IH was evaluated on C57BL/6J mice developing lung fibrosis after intratracheal instillation of Bleomycin (BLM). Mice were Pre-exposed 14 days to IH before induction of lung fibrosis or Co-challenged with IH and BLM for 14 days. Weight loss and survival were daily monitored. After experimentations, lungs were sampled for histology, and protein and RNA were extracted. RESULTS: Co-challenge or Pre-exposure of IH and BLM induced weight loss, increased tissue injury and collagen deposition, and pro-fibrotic markers. Major worsening effects of IH exposure on lung fibrosis were observed when mice were Pre-exposed to IH before developing lung fibrosis with a strong increase in sXBP1 and ATF6N ER stress markers. CONCLUSION: Our results showed that IH exacerbates BLM-induced lung fibrosis more markedly when IH precedes lung fibrosis induction, and that this is associated with an enhancement of ER stress markers.