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Cysteinyl leukotriene (cysLT) overproduction and eosinophil activation are hallmarks of aspirin-exacerbated respiratory disease (AERD). However, pathogenic mechanisms of AERD remain to be clarified. Here, we aimed to find the significance of transforming growth factor beta 1 (TGF-β1) in association with cysteinyl leukotriene E 4 (LTE 4 ) production, leading to eosinophil degranulation. To evaluate levels of serum TGF-β1, first cohort enrolled AERD (n = 336), ATA (n = 442) patients and healthy control subjects (HCs, n = 253). In addition, second cohort recruited AERD (n = 34) and ATA (n = 25) patients to investigate a relation between levels of serum TGF-β1 and urinary LTE 4 . The function of TGF-β1 in LTE 4 production was further demonstrated by ex vivo (human peripheral eosinophils) or in vivo (BALB/c mice) experiment. As a result, the levels of serum TGF-β1 were significantly higher in AERD patients than in ATA patients or HCs ( P = .001; respectively). Moreover, levels of serum TGF-β1 and urinary LTE 4 had a positive correlation ( r = 0.273, P = .037). In the presence of TGF-β1, leukotriene C 4 synthase (LTC 4 S) expression was enhanced in peripheral eosinophils to produce LTE 4 , which sequentially induced eosinophil degranulation via the p38 pathway. When mice were treated with TGF-β1, significantly induced eosinophilia with increased LTE 4 production in the lung tissues were noted. These findings suggest that higher levels of TGF-β1 in AERD patients may contribute to LTE 4 production via enhancing LTC 4 S expression which induces eosinophil degranulation, accelerating airway inflammation.

To investigate the immune response and mechanisms associated with severe coronavirus disease 2019 (COVID-19), we performed single-cell RNA sequencing on nasopharyngeal and bronchial samples from 19 clinically well-characterized patients with moderate or critical disease and from five healthy controls. We identified airway epithelial cell types and states vulnerable to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In patients with COVID-19, epithelial cells showed an average three-fold increase in expression of the SARS-CoV-2 entry receptor ACE2, which correlated with interferon signals by immune cells. Compared to moderate cases, critical cases exhibited stronger interactions between epithelial and immune cells, as indicated by ligand–receptor expression profiles, and activated immune cells, including inflammatory macrophages expressing CCL2, CCL3, CCL20, CXCL1, CXCL3, CXCL10, IL8, IL1B and TNF. The transcriptional differences in critical cases compared to moderate cases likely contribute to clinical observations of heightened inflammatory tissue damage, lung injury and respiratory failure. Our data suggest that pharmacologic inhibition of the CCR1 and/or CCR5 pathways might suppress immune hyperactivation in critical COVID-19.Single-cell analysis of COVID-19 patient samples identifies activated immune pathways that correlate with severe disease.

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has led to a global public health crisis. In elderly individuals and those with comorbidities, COVID-19 is associated with high mortality, frequently caused by acute respiratory distress syndrome. We examine in situ expression of SARS-CoV-2 in airways and lung obtained at autopsy of individuals with confirmed COVID-19 infection. Seven autopsy cases (male, N = 5; female, N = 2) with reverse transcriptase-polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection and a median age of 66 years (range, 50–77 years) were evaluated using a rabbit polyclonal antibody against SARS Nucleocapsid protein in correlation with clinical parameters. The median time from symptom onset to death was 9 days (range, 6–31 days), from hospitalization 7 days (range, 1–21 days), from positive RT-PCR 7 days (range, 0–18 days), and from intensive care unit admission defining onset of respiratory failure 3 days (range, 1–18 days). Chest imaging identified diffuse airspace disease in all patients corresponding to acute and (N = 5) or organizing (N = 2) diffuse alveolar damage (DAD) on histologic examination. Among five patients with acute-phase DAD (≤7 days from onset of respiratory failure), SARS-CoV-2 was detected in pulmonary pneumocytes and ciliated airway cells (N = 5), and in upper airway epithelium (N = 2). In two patients with organizing DAD (>14 days from onset of respiratory failure), no virus was detected in lungs or airways. No endothelial cell infection was observed. The findings suggest that SARS-CoV-2 infection of epithelial cells in lungs and airways of patients with COVID-19 who developed respiratory failure can be detected during the acute phase of lung injury and is absent in the organizing phase.

The authors report the emergence and isolation of a previously unknown betacoronavirus, the seventh member of the family of coronaviruses that infect humans, in Wuhan, China. Findings in three patients are described.

Coronavirus disease 2019 (COVID-19) is known to cause multi-organ dysfunction 1 – 3 during acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with some patients experiencing prolonged symptoms, termed post-acute sequelae of SARS-CoV-2 (refs.  4 , 5 ). However, the burden of infection outside the respiratory tract and time to viral clearance are not well characterized, particularly in the brain 3 , 6 – 14 . Here we carried out complete autopsies on 44 patients who died with COVID-19, with extensive sampling of the central nervous system in 11 of these patients, to map and quantify the distribution, replication and cell-type specificity of SARS-CoV-2 across the human body, including the brain, from acute infection to more than seven months following symptom onset. We show that SARS-CoV-2 is widely distributed, predominantly among patients who died with severe COVID-19, and that virus replication is present in multiple respiratory and non-respiratory tissues, including the brain, early in infection. Further, we detected persistent SARS-CoV-2 RNA in multiple anatomic sites, including throughout the brain, as late as 230 days following symptom onset in one case. Despite extensive distribution of SARS-CoV-2 RNA throughout the body, we observed little evidence of inflammation or direct viral cytopathology outside the respiratory tract. Our data indicate that in some patients SARS-CoV-2 can cause systemic infection and persist in the body for months. A study reports the distribution, replication and persistence of SARS-CoV-2 throughout the human body including in the brain at autopsy from acute infection to more than seven months following symptom onset.

The pathophysiologic causes of obstructive sleep apnea (OSA) likely vary among patients but have not been well characterized. To define carefully the proportion of key anatomic and nonanatomic contributions in a relatively large cohort of patients with OSA and control subjects to identify pathophysiologic targets for future novel therapies for OSA. Seventy-five men and women with and without OSA aged 20-65 years were studied on three separate nights. Initially, the apnea-hypopnea index was determined by polysomnography followed by determination of anatomic (passive critical closing pressure of the upper airway [Pcrit]) and nonanatomic (genioglossus muscle responsiveness, arousal threshold, and respiratory control stability; loop gain) contributions to OSA. Pathophysiologic traits varied substantially among participants. A total of 36% of patients with OSA had minimal genioglossus muscle responsiveness during sleep, 37% had a low arousal threshold, and 36% had high loop gain. A total of 28% had multiple nonanatomic features. Although overall the upper airway was more collapsible in patients with OSA (Pcrit, 0.3 [-1.5 to 1.9] vs. -6.2 [-12.4 to -3.6] cm H2O; P <0.01), 19% had a relatively noncollapsible upper airway similar to many of the control subjects (Pcrit, -2 to -5 cm H2O). In these patients, loop gain was almost twice as high as patients with a Pcrit greater than -2 cm H2O (-5.9 [-8.8 to -4.5] vs. -3.2 [-4.8 to -2.4] dimensionless; P = 0.01). A three-point scale for weighting the relative contribution of the traits is proposed. It suggests that nonanatomic features play an important role in 56% of patients with OSA. This study confirms that OSA is a heterogeneous disorder. Although Pcrit-anatomy is an important determinant, abnormalities in nonanatomic traits are also present in most patients with OSA.

The coronavirus SARS-CoV-2 is the causative agent of the ongoing severe acute respiratory disease pandemic COVID-19. Tissue and cellular tropism is one key to understanding the pathogenesis of SARS-CoV-2. We investigate the expression and subcellular localization of the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), within the upper (nasal) and lower (pulmonary) respiratory tracts of human donors using a diverse panel of banked tissues. Here, we report our discovery that the ACE2 receptor protein robustly localizes within the motile cilia of airway epithelial cells, which likely represents the initial or early subcellular site of SARS-CoV-2 viral entry during host respiratory transmission. We further determine whether ciliary ACE2 expression in the upper airway is influenced by patient demographics, clinical characteristics, comorbidities, or medication use, and show the first mechanistic evidence that the use of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARBs) does not increase susceptibility to SARS-CoV-2 infection through enhancing the expression of ciliary ACE2 receptor. These findings are crucial to our understanding of the transmission of SARS-CoV-2 for prevention and control of this virulent pathogen. Understanding how SARS-CoV-2 gains initial entry into the human body is a key step towards the development of prophylaxes and therapeutics for COVID-19. Here, the authors show that ACE2, the receptor for SARS-CoV-2, is abundantly expressed in the motile cilia of the human nasal and respiratory tract and is not affected by the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers.

SARS-CoV-2, a β-coronavirus, has rapidly spread across the world, highlighting its high transmissibility, but the underlying morphogenesis and pathogenesis remain poorly understood. Here, we characterize the replication dynamics, cell tropism and morphogenesis of SARS-CoV-2 in organotypic human airway epithelial (HAE) cultures. SARS-CoV-2 replicates efficiently and infects both ciliated and secretory cells in HAE cultures. In comparison, HCoV-NL63 replicates to lower titers and is only detected in ciliated cells. SARS-CoV-2 shows a similar morphogenetic process as other coronaviruses but causes plaque-like cytopathic effects in HAE cultures. Cell fusion, apoptosis, destruction of epithelium integrity, cilium shrinking and beaded changes are observed in the plaque regions. Taken together, our results provide important insights into SARS-CoV-2 cell tropism, replication and morphogenesis. Here, the authors characterize replication of SARS-CoV-2 in human airway epithelial (HAE) cultures and show that it can infect ciliated and secretory cells, affects transepithelial electrical resistance and causes plaque-like cytopathic effects associated with apoptosis.

The immunopathology of coronavirus disease 2019 (COVID-19) remains enigmatic, causing immunodysregulation and T cell lymphopenia. Monocytic myeloid-derived suppressor cells (M-MDSCs) are T cell suppressors that expand in inflammatory conditions, but their role in acute respiratory infections remains unclear. We studied the blood and airways of patients with COVID-19 across disease severities at multiple time points. M-MDSC frequencies were elevated in blood but not in nasopharyngeal or endotracheal aspirates of patients with COVID-19 compared with healthy controls. M-MDSCs isolated from patients with COVID-19 suppressed T cell proliferation and IFN-γ production partly via an arginase 1-dependent (Arg-1-dependent) mechanism. Furthermore, patients showed increased Arg-1 and IL-6 plasma levels. Patients with COVID-19 had fewer T cells and downregulated expression of the CD3ζ chain. Ordinal regression showed that early M-MDSC frequency predicted subsequent disease severity. In conclusion, M-MDSCs expanded in the blood of patients with COVID-19, suppressed T cells, and were strongly associated with disease severity, indicating a role for M-MDSCs in the dysregulated COVID-19 immune response.

Novel reassortant avian influenza H7N9 virus and pandemic 2009 H1N1 (H1N1pdm) virus cause human infections, while avian H7N2 and swine H1N1 virus mainly infect birds and pigs, respectively. There is no robust in vitro model for assessing the infectivity of emerging viruses in humans. Based on a recently established method, we generated long-term expanding 3D human airway organoids which accommodate four types of airway epithelial cells: ciliated, goblet, club, and basal cells. We report differentiation conditions which increase ciliated cell numbers to a nearly physiological level with synchronously beating cilia readily discernible in every organoid. In addition, the differentiation conditions induce elevated levels of serine proteases, which are essential for productive infection of human influenza viruses and low-pathogenic avian influenza viruses. We also established improved 2D monolayer culture conditions for the differentiated airway organoids. To demonstrate the ability of differentiated airway organoids to identify human-infective virus, 3D and 2D differentiated airway organoids are applied to evaluate two pairs of viruses with known distinct infectivity in humans, H7N9/Ah versus H7N2 and H1N1pdm versus an H1N1 strain isolated from swine (H1N1sw). The human-infective H7N9/Ah virus replicated more robustly than the poorly human-infective H7N2 virus; the highly human-infective H1N1pdm virus replicated to a higher titer than the counterpart H1N1sw. Collectively, we developed differentiated human airway organoids which can morphologically and functionally simulate human airway epithelium. These differentiated airway organoids can be applied for rapid assessment of the infectivity of emerging respiratory viruses to human.