Next-generation proteomics of serum extracellular vesicles combined with single-cell RNA sequencing identifies MACROH2A1 associated with refractory COVID-19.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is widespread; however, accurate predictors of refractory cases have not yet been established. Circulating extracellular vesicles, involved in many pathological processes, are ideal resources for biomarker exploration. METHODS: To identify potential serum biomarkers and examine the proteins associated with the pathogenesis of refractory COVID-19, we conducted high-coverage proteomics on serum extracellular vesicles collected from 12 patients with COVID-19 at different disease severity levels and 4 healthy controls. Furthermore, single-cell RNA sequencing of peripheral blood mononuclear cells collected from 10 patients with COVID-19 and 5 healthy controls was performed. RESULTS: Among the 3046 extracellular vesicle proteins that were identified, expression of MACROH2A1 was significantly elevated in refractory cases compared to non-refractory cases; moreover, its expression was increased according to disease severity. In single-cell RNA sequencing of peripheral blood mononuclear cells, the expression of MACROH2A1 was localized to monocytes and elevated in critical cases. Consistently, single-nucleus RNA sequencing of lung tissues revealed that MACROH2A1 was highly expressed in monocytes and macrophages and was significantly elevated in fatal COVID-19. Moreover, molecular network analysis showed that pathways such as "estrogen signaling pathway," "p160 steroid receptor coactivator (SRC) signaling pathway," and "transcriptional regulation by STAT" were enriched in the transcriptome of monocytes in the peripheral blood mononuclear cells and lungs, and they were also commonly enriched in extracellular vesicle proteomics. CONCLUSIONS: Our findings highlight that MACROH2A1 in extracellular vesicles is a potential biomarker of refractory COVID-19 and may reflect the pathogenesis of COVID-19 in monocytes.

Case report: Acute exacerbation of interstitial pneumonia related to messenger RNA COVID-19 vaccination.

Messenger RNA (mRNA) vaccines that protect against COVID-19 are widely used in many countries owing to their high efficacy and safety profiles. Recently, few severe adverse events, such as anaphylaxis and myocarditis, were reported in healthy individuals. The safety of mRNA COVID-19 vaccines has not been adequately studied in patients with interstitial lung disease. We report 2 cases of acute exacerbation of preexisting interstitial pneumonia associated with mRNA COVID-19 vaccination. In both cases, lung disease was stable before the vaccination. Initial responses to steroid therapy were unfavorable, and intravenous cyclophosphamide was administered in both cases. Both patients were diagnosed with vaccine-related exacerbation of interstitial pneumonia based on laboratory results, radiologic features, and the observed clinical course, which lacked other causative events. We suggest that clinicians should note the possibility of acute exacerbation of pneumonia after mRNA COVID-19 vaccination and carefully monitor patients with interstitial lung disease.

COVID-19 in a human T-cell lymphotropic virus type-1 carrier.

This is the first report of COVID-19 in a human T-cell lymphotropic virus type-1 (HTLV-1) carrier. HTLV-1 infection can cause immune dysfunction even in asymptomatic carriers. This case highlights the need for guidance on management of COVID-19-HTLV-1 coinfection, specifically on the appropriate use of corticosteroid treatment while considering secondary infection.

COVID-19 in a patient with sporadic lymphangioleiomyomatosis awaiting lung transplantation.

Coronavirus disease 2019 (COVID-19) is an emerging viral disease with a mortality that depends on the individual's condition. Underlying comorbidities are major risk factors for COVID-19-related morbidity and mortality. However, information regarding the clinical course of COVID-19 in patients with rare respiratory system diseases is lacking. Here, we present a case of severe COVID-19 in a patient with advanced sporadic lymphangioleiomyomatosis (LAM) who was awaiting lung transplantation. She experienced a marked worsening of her respiratory status despite the limited size of the infiltrations seen on chest computed tomography. She responded to treatment with dexamethasone and remdesivir, and did not require mechanical ventilation. She recovered her pre-COVID-19 respiratory function. This case illustrates that patients with severe lung parenchymal destruction due to advanced LAM are at risk of worsening hypoxemia, but may not have a bad outcome if managed appropriately. Prevention and early diagnosis of COVID-19 are crucial in patients with advanced LAM. Future studies are needed to improve understanding of the clinical features and optimal treatment of COVID-19 in patients with LAM.

Fatal cytomegalovirus pneumonia in a critically ill patient with COVID-19.

Coronavirus disease 2019 (COVID-19) can cause severe lymphopenia and respiratory failure requiring prolonged invasive mechanical ventilation (MV). COVID-19 patients with severe lymphopenia or respiratory failure are at risk of developing secondary infections. Here, we present the needle autopsy findings of a critically ill patient with COVID-19 who required reintubation and prolonged MV, and eventually died of secondary cytomegalovirus (CMV) pneumonia. This case highlights the potential risk of long-term steroid use and the need for routine monitoring for CMV infection in critically ill patients with COVID-19.