Patient Outcomes in CMV and SARS-CoV-2 Coinfection

This study examines clinical outcomes in patients with cytomegalovirus (CMV) and SARS-CoV-2 coinfection. Between June and November 2020, previously immunocompetent patients with SARS-CoV-2 and CMV coinfection were identified at Houston Methodist Hospital as part of routine clinical correlation by a molecular pathologist. SARS-CoV-2 nasopharyngeal specimens were analyzed by real time reverse-transcriptase polymerase chain reaction (RT-PCR). All CMV tests were performed on plasma or bronchoalveolar lavage (BAL) specimens and analyzed by competitive polymerase chain reaction. 65 previously immunocompetent patients with CMV and SARS-CoV-2 coinfection were identified. Patient demographics include 41 male patients (63%) and 24 female patients (37%) ranging in age from 34 to 86 years (mean: 66.04, median 68). Documented pre-existing conditions include 27 patients with hypertension 41.5%), 19 patients with diabetes mellitus (29.2%), 9 patients with coronary artery disease (13.8%), and 3 patients with asthma (4.6%). Eight patients (12.3%) had no documented pre-existing conditions. The plasma CMV viral load ranged from <300 to 21,566 IU/mL. The CMV PCR results from bronchoalveolar lavage and bronchial wash specimens ranged from <300 to 59,127 IU/mL. CMV PCR was initially negative in 10 patients then positive on serial testing. 60 patients were critically ill requiring ventilator support (92.3%). 47 patients (72.3%) expired, 7 patients (10.8%) were transferred to a long term acute care facility, 3 patients (4.6%) were discharged to a rehabilitation facility, 3 patients (4.6%) were discharged home, and 1 patient (1.5%) remained in-patient at the time of analysis. The prevalence of CMV seropositivity and medical comorbidities increases with age. Reactivation of latent CMV is a known occurrence in critically ill patients that is associated with poor outcomes. The majority of the patients in our cohort were 50 years old, and all were severely to critically ill with a mortality rate of 72.3% These findings suggest CMV portends a worse prognosis in patients with COVID-19. These findings also demonstrate the importance of clinical correlation in molecular testing.

Barotrauma in a Previously Healthy and Young COVID-19 Patient: an Autopsy Case Report

Introduction/Objective Since the emergence of a novel SARS-CoV-2 virus caused coronavirus disease 2019 (COVID-19), a great number of autopsy studies have been published. However, histopathologic studies focused on pulmonary barotrauma are very rare. Here we report an autopsy confined to the lungs on a young COVID-19 patient. Methods/Case Report The patient was a 37-year-old male, non-smoker, with no significant past medical history, and a body mass index of 24.1, who presented with shortness of breath and cough. A computerized tomography (CT) showed features of atypical pneumonia. The main abnormal laboratory data included elevated partial thromboplastin time, fibrinogen, and D-Dimer. The patient had been on mechanical ventilation for 35 days, and was complicated by recurrent pneumothoraces, hypotension, and worsening hypoxia. An autopsy limited to the lungs was performed after the patient expired. Grossly, the lungs showed increased weight, adhesions on visceral pleural surface, patchy consolidation and dilated subpleural cysts. Histological examination revealed cystically dilated/remodeled airspaces with extensive coagulative necrosis, focal alveolar hemorrhage and edema, focal confluent fibrosis, and subpleural blebs. Fresh fibrinous thrombi were seen in small- and medium-sized vessels. Viral cytopathic changes or significant inflammation were not observed. The findings in the lungs were consistent with barotrauma in COVID-19. Results (if a Case Study enter NA) NA. Conclusion This case demonstrates various histopathologic changes of the lungs in a previously healthy and young COVID-19 patient with prolonged hospital course of mechanical ventilation. The features of diffuse alveolar damage with inflammation usually seen in the early stage of barotrauma are not identified. Our findings in the lungs may represent the histopathologic characteristics of the later stage of barotrauma in COVID-19.

TIME MANAGEMENT AND RISK FACTORS IN LIFE-THREATENING ANCA-VASCULITIS

BackgroundAccuracy of diagnosis and prompt therapeutic intervention are the mainstay in patients with ANCA-associated vasculitis(AAV) suffering from life-threatening complications [1].However, there is no definition of therapeutic window in vital AAV, nor its impact on patient outcome regarding length of hospital stay, intensive care unit(ICU) admission or survival.ObjectivesThe aim of the study is to analyze the process of care from the perspective of time management in vital organ involvement AAV patients and to identify potential risk factors for ICU admission.MethodsA retrospective multicenter study identified AAV patients with life-threatening organ involvement, defined as alveolar hemorrhage, rapidly progressive renal failure, myocarditis and cerebral granuloma. Demographic data was collected. Key time frames were recorded, namely the interval from acute symptom onset to hospital presentation, days until imaging(plain X-ray, cardiac ultrasound, CT-scan), time to therapeutic intervention with corticosteroids or biologic/non-biologic immunosuppression(cyclophosphamide or rituximab) and to renal replacement therapy(RRT) or plasmapheresis. Time to ICU admission, hospital length-of-stay, Birmingham Vasculitis Activity Score(BVAS) were also noted. Statistical analysis was performed using SPSS and Chi-square and Pearson correlation tests were applied.Results66 patients with AAV were enrolled, out of which 17 fulfilled inclusion criteria. Mean age in the study group was 58.6±11.1 years old,10 patients(58.8%) were females and 7 (41.2%) males.11(64.7%) patients were c-ANCA positive, while 6 (35.3%) had p-ANCA and all were diagnosed with AAV prior to life-threatening event. Two patients had COVID-19 triggered AAV.In the study group, the most frequent critical organ suffering was rapidly progressive renal failure(12), followed by alveolar hemorrhages(10), 2 cerebral granulomas and one acute myocarditis. Three patients(17.6%) had more than one vital manifestation. Ten patients(58.8%) had more than three additional non-organ-threatening manifestations. Mean interval from AAV diagnosis to emergency admission was 30.1± 61.1 days, median 3 and from severe episode onset to hospitalization 1.65±0.18 days, median 1. There was only one death in the study group. Three patients were admitted in the ICU in 0.59±1.5 days following hospital presentation and required either RRT or plasma exchange within 2.66 days. Imaging examination was performed unanimously the day upon hospital admission. All patients received corticosteroids in the first 5.95±14.3 days, while immunosuppression was given to 13(76.5%) patients within 11.5±15.5 days from hospitalization.12 patients(70.5%) suffered from associated infections. Mean BVAS(13.6±6.76) correlated to ICU admission(p 0.013, r 0.58).Patients in ICU revealed higher BVAS(22±9.53) versus non-ICU(11.8±4.76).Hospital length of stay was 14.7±10.7 days(median 14) and showed no relationship to the type of severe organ involvement. The need for ICU caring was dominant in males(p 0.05) and confirmed in patients with proteinuria(p 0.012) and at least two major organ damage.ConclusionThis study shows that severity risk factors for potential ICU admission for life-threatening AAV appear to be male gender, proteinuria and the number of affected organs.Moreover, BVAS should be considered a useful tool to predict patients' risk for intensive care management since a higher score indicates a more aggressive disease.However, time to investigational or therapeutic intervention did not correlate to patient outcome in AAV.References[1]Geetha, D., Seo, P. (2011). Life-Threatening Presentations of ANCA-Associated Vasculitis. In: Khamashta, M., Ramos-Casals, M. (eds) Autoimmune Diseases. Springer, London. https://doi.org/10.1007/978-0-85729-358-9_8Acknowledgements:NIL.Disclosure of InterestsNone Declared.

The Foggy Lungs: A Case Report on Pulmonary Alveolar Proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare interstitial lung disease characterized by macrophage dysfunction leading to the accumulation of surfactant in the alveoli and bronchiolar spaces, leading to impaired gas exchange and severe hypoxemia. The underlying mechanisms of PAP are not fully understood, but it is believed to involve impaired clearance of surfactant and abnormal immune responses. Diagnosis of PAP typically involves imaging studies and bronchoscopy, and treatment options include whole-lung lavage, pharmacotherapy, and lung transplantation. We report PAP in a 56-year-old female who worked in a dental office and had no prior diagnosis of lung disease.

Rapid Generation of Pulmonary Organoids from Induced Pluripotent Stem Cells by Co-Culturing Endodermal and Mesodermal Progenitors for Pulmonary Disease Modelling.

Differentiation of induced pluripotent stem cells to a range of target cell types is ubiquitous in monolayer culture. To further improve the phenotype of the cells produced, 3D organoid culture is becoming increasingly prevalent. Mature organoids typically require the involvement of cells from multiple germ layers. The aim of this study was to produce pulmonary organoids from defined endodermal and mesodermal progenitors. Endodermal and mesodermal progenitors were differentiated from iPSCs and then combined in 3D Matrigel hydrogels and differentiated for a further 14 days to produce pulmonary organoids. The organoids expressed a range of pulmonary cell markers such as SPA, SPB, SPC, AQP5 and T1α. Furthermore, the organoids expressed ACE2 capable of binding SARS-CoV-2 spike proteins, demonstrating the physiological relevance of the organoids produced. This study presented a rapid production of pulmonary organoids using a multi-germ-layer approach that could be used for studying respiratory-related human conditions.

Role of angiotensin II in SARS-CoV-2 pathophysiology in a hamster model of COVID-19

OBJECTIVES/GOALS: Hamsters develop COVID-19 similarly to people because the SARS-CoV-2 spike protein binds with high affinity to hamster ACE2 resulting in host cell entry and replication. Our goal was to establish a hamster model that mirrors the lung and brain pathophysiology observed in COVID-19. METHODS/STUDY POPULATION: Hamsters infected with SARS CoV-2 are sacrificed on day 1 and day 6 postinfection. Lung histopathology scoring model was implemented for assessment all pathological relevant changes in the lungs of infected animals on tissue sections stained with hematoxylin and eosin. To quantify the extent and severity of lung pathology, two scoring systems were used: the first evaluated all relevant changes in the lungs of the infected animals and the second evaluated only the pathology associated with the pulmonary vasculature. Percentage of airway affected, airway severity, bronchiolar epithelial hyperplasia, alveoli affected, alveolar severity, type II pneumocyte hyperplasia and vessels affected were analyzed. Total airway score plus total lung alveolar score give lung histopathology score. RESULTS/ANTICIPATED RESULTS: Compared to the control hamster, the hamsters day 1 postinfection, exhibited a higher total airway score [9.00 ± 1.35 vs. 0.25 ± 0.1;p DISCUSSION/SIGNIFICANCE: Establishing this outstanding small animal model of COVID-19 will facilitate studies investigating diagnostics, prognosis and response to treatment in COVID-19 disease. These studies will provide insights that will complement on-going clinical trials on angiotensin type 1 receptor (AT1R) blockers (ARBs) in COVID-19.

A novel mouse model of COVID-19

OBJECTIVES/GOALS: Rodents are the most widely used experimental animals to study disease mechanisms due to their availability and cost-effectiveness. An international drive to investigate the pathophysiology of COVID-19 is inhibited by the resistance of rats and mice to SARS-CoV-2 infection. Our goal was to establish an appropriate small animal model. METHODS/STUDY POPULATION: To recreate the cytokine storm that is associated with COVID-19, we injected angiotensin converting enzyme 2 knockout (ACE2KO) mice (C57BI/6 strain) with lipopolysaccharide (LPS) intraperitoneally and measured the expression of multiple cytokines as a function of time and LPS dose. We then chose a minimum dose (500ug/kg) and time (3h) when multiple cytokines were elevated to measure lung injury scores using a point-counting technique on tissue sections stained with hematoxylin and eosin. The data are expressed as mean percentage of grid points lying within the peribronchial and superficial area in up to 20 fields. Percentage of peribronchial and superficial intrapulmonary hemorrhage, congestion, neutrophil infiltration and area of alveolar space were all assessed. RESULTS/ANTICIPATED RESULTS: Compared to the wildtype group (WT-G), the LPS-injected ACE2KO mice (LPS-G) exhibited a higher percentage of peribronchial intrapulmonary hemorrhage [(%): LPS-G, 10.56 ± 2.06 vs. WT-G, 5.59 ± 0.53;p DISCUSSION/SIGNIFICANCE: Establishing this novel mouse model of COVID-19 will facilitate studies investigating tissue-specific mechanisms of pathogenesis in this disease. This model can also be used to discover novel therapeutic targets and the design of clinical trials focusing on diagnostics, treatments and outcomes in COVID-19.

Proposed cardio-pulmonary model to investigate the effects of COVID-19 on the cardiovascular system.

In this paper, we propose a new mathematical model of cardiovascular system coupled with a respiratory system to study the effects of COVID-19 on global blood circulation parameters using the lumped parameters model. We use the fourth-order Runge-Kutta method for solving the sets of equations of motion. We validate our model by showing that the simulated flows in pulmonary and aortic valves corroborate, respectively, the results established by Smith et al. [IFAC Proceedings Volumes, 39 (2006) 453-458]. Then we examine the effects of the new coronavirus (covid-19) on the cardiopulmonary system through the impact of the high respiratory frequency and the variation of the alveoli volume. To achieve this aim, we propose a new exponential law for the time varying of the pulmonary resistance. It appears that when the respiratory frequency grows, the delay between the systemic artery flow and the flow in the pulmonary artery diminishes. Therefore, the efficiency of the cardiac pump is reduced. Moreover, our results also show that variations of the alveoli volume cause the increment of the pleural pressure in the vascular cavities that induces an exponential growth of the pulmonary resistance. Furthermore, this growth of the pulmonary resistance provokes the augmentation of pressure in some organs and its reduction in others. We found that patient with covid-19 having a prior history of cardiovascular diseases is exposed to a severe case of inflammation/damage of certain organs than those with no history of cardiovascular disease.

Impaired cell-cell communication and axon guidance because of pulmonary hypoperfusion during postnatal alveolar development.

BACKGROUND: Pulmonary hypoperfusion is common in children with congenital heart diseases (CHDs) or pulmonary hypertension (PH) and causes adult pulmonary dysplasia. Systematic reviews have shown that some children with CHDs or PH have mitigated clinical outcomes with COVID-19. Understanding the effects of pulmonary hypoperfusion on postnatal alveolar development may aid in the development of methods to improve the pulmonary function of children with CHDs or PH and improve their care during the COVID-19 pandemic, which is characterized by cytokine storm and persistent inflammation. METHODS AND RESULTS: We created a neonatal pulmonary hypoperfusion model through pulmonary artery banding (PAB) surgery at postnatal day 1 (P1). Alveolar dysplasia was confirmed by gross and histological examination at P21. Transcriptomic analysis of pulmonary tissues at P7(alveolar stage 2) and P14(alveolar stage 4) revealed that the postnatal alveolar development track had been changed due to pulmonary hypoperfusion. Under the condition of pulmonary hypoperfusion, the cell-cell communication and axon guidance, which both determine the final number of alveoli, were lost; instead, there was hyperactive cell cycle activity. The transcriptomic results were further confirmed by the examination of axon guidance and cell cycle markers. Because axon guidance controls inflammation and immune cell activation, the loss of axon guidance may explain the lack of severe COVID-19 cases among children with CHDs or PH accompanied by pulmonary hypoperfusion. CONCLUSIONS: This study suggested that promoting cell-cell communication or supplementation with guidance molecules may treat pulmonary hypoperfusion-induced alveolar dysplasia, and that COVID-19 is less likely to cause a cytokine storm in children with CHD or PH accompanied by pulmonary hypoperfusion.

Angiotensin-converting enzyme-2 and interleukin-12 serum level as indicator to severity between COVID-19 patients

The Coronavirus, one of the most rapidly spreading respiratory viruses, caused a worldwide epidemic that killed about six million people. This led to the fast development of several vaccines and drugs to reduce disease severity and speed patient recovery. This study aimed to identify the serum levels of each of the angiotensin-converting enzyme-2 and interleukin-12 .The severity of infection in coronavirus COVID-19 patients was compared to immune levels of these cytokines and receptors in the different cases of COVID-19 patients. This case-control study included 90 blood samples from COVID-19 patients with ages between 15-80 years. Results revealed that the serum levels of both angiotensin-converting enzyme-2 ( ACE-2) and interleukin-12 (IL-12) were measured in COVID-19 patients and the results were compared using an independent T-test, it was found that their levels for interleukin-12 revealed a significant difference (P ≤0.05) in the serum levels of severe cases when compared with non-severe cases. There was an increase in the serum level of IL-12 in severe cases was 33.340 ng/L, in the serum level and in non-severe cases was 20.913 ng/L. ( P ≤0.000), and for angiotensin-converting enzyme-2 this study revealed a significant difference in ACE-2 serum levels in severe cases (P ≤0.05) when compared with the non-severe cases of patients with COVID 19. The serum level of ACE-2 in severe cases was 11.023 ng/ml, and in non-severe cases, it was 5.443ng/ml ( P ≤0.000). It was concluded that the emerging coronavirus works to create an immune storm represented by raising the serum levels of both ACE-2 and IL-12 that contribute to the damage to the alveoli in severely COV-19 patients.

Function of epithelial stem cell in the repair of alveolar injury.

Alveoli are the functional units of blood-gas exchange in the lung and thus are constantly exposed to outside environments and frequently encounter pathogens, particles and other harmful substances. For example, the alveolar epithelium is one of the primary targets of the SARS-CoV-2 virus that causes COVID-19 lung disease. Therefore, it is essential to understand the cellular and molecular mechanisms by which the integrity of alveoli epithelial barrier is maintained. Alveolar epithelium comprises two cell types: alveolar type I cells (AT1) and alveolar type II cells (AT2). AT2s have been shown to function as tissue stem cells that repair the injured alveoli epithelium. Recent studies indicate that AT1s and subgroups of proximal airway epithelial cells can also participate alveolar repair process through their intrinsic plasticity. This review discussed the potential mechanisms that drive the reparative behaviors of AT2, AT1 and some proximal cells in responses to injury and how an abnormal repair contributes to some pathological conditions.

Identifying Community-Acquired Pneumonia During the COVID-19 Pandemic

* Pneumonia is an infection of the alveoli characterized by fever, cough, and pulmonary infiltrate. * Prior to COVID-19, the most common pathogens found in adults hospitalized with pneumonia were rhinovirus, influenza, and Streptococcus pneumoniae. * The identification of a pathogen is increased in severe cases of pneumonia and when multiple detection techniques are used. * Blood cultures are not recommended for routine cases of pneumonia. * SARS-CoV-2 and influenza testing is recommended when either is prevalent in the community. * Healthy patients with suspected bacterial community-acquired pneumonia and who are otherwise suitable for discharge can be treated with a course of oral antibiotics for five to seven days. * Patients with comorbidities who are appropriate for discharge should be treated with either an amoxicillin/clavulanic acid or a cephalosporin in addition to treatment with a macrolide or doxycycline for seven days. * The concept of healthcare-associated pneumonia is not useful to identify patients at increased risk for infection from drug-resistant organisms. * Scoring tools can be used to support clinical judgment in determining patients with a low mortality risk who may be appropriate for outpatient treatment. * The effectiveness of monoclonal antibodies and antivirals is subject to change because of the potential development of resistance to newer variants.

The Beneficial Effects of QIAPI 1® against Pentavalent Arsenic-Induced Lung Toxicity: A Hypothetical Model for SARS CoV2-I nduced Lung Toxicity.

Exposure to environmental toxicants such as Arsenic (As) can result in As-induced alterations in immune regulators. Consequently, people who are more prone to viral infections like influenza A or B, H1N1, SARS CoV (Severe Acute Respiratory Syndrome Coronavirus), and SARS CoV2 may develop a susceptibility to immune responses in their lungs because our previous reports delineated the ability of QIAPI 1®, a melanin precursor, to dissociate water molecules with simultaneous therapeutic efficacy against central nervous system (CNS) diseases, retinopathy, and As-induced renal toxicity. Considering the commonalitie of lung pathology of SARS CoV and As-induced toxicity, the aim of this study is to decipher the efficacy of QIAPI 1® against pentavalent As-induced lung toxicity by examining the pulmonary pathology. Hematoxylin & Eosin (H&E) staining was used for ascertaining the lung pathology in Wistar rat models. Animals were divided into 3 groups: control group, group treated with pentavalent As, and a group treated with pentavalent As and QIAPI 1®. There were no significant changes in lung histopathology in the control group as indicated by intact morphology. The As-treated group revealed damage to the histoarchitecture with pulmonary edema, interstitial fibrosis, diffuse alveolar damage, Bronchiolitis obliterans organizing pneumonia (BOOP)-lesions, formation of hyaline membrane, multinucleated giant pneumocytes, atypical pneumocytes, inflammatory cell infiltration, and interstitial edema. The group treated with As and QIAPI 1® significantly associated with mitigated histological signs of lung inflammation induced by Arsenic. Therefore, QIAPI 1® can be recommended as antagonistic to Asinduced lung toxicity. In conclusion, this model could be preferred as a hypothetical model to examine the efficacy of QIAPI 1® in SARS CoV2-induced pulmonary damage. Future studies are warranted to delineate the efficacy of QIAPI 1® against SARS CoV and SARS CoV2 lung pathology.

AI-guided discovery of the invariant host response to viral pandemics.

BACKGROUND: Coronavirus Disease 2019 (Covid-19) continues to challenge the limits of our knowledge and our healthcare system. Here we sought to define the host immune response, a.k.a, the "cytokine storm" that has been implicated in fatal COVID-19 using an AI-based approach. METHOD: Over 45,000 transcriptomic datasets of viral pandemics were analyzed to extract a 166-gene signature using ACE2 as a 'seed' gene; ACE2 was rationalized because it encodes the receptor that facilitates the entry of SARS-CoV-2 (the virus that causes COVID-19) into host cells. An AI-based approach was used to explore the utility of the signature in navigating the uncharted territory of Covid-19, setting therapeutic goals, and finding therapeutic solutions. FINDINGS: The 166-gene signature was surprisingly conserved across all viral pandemics, including COVID-19, and a subset of 20-genes classified disease severity, inspiring the nomenclatures ViP and severe-ViP signatures, respectively. The ViP signatures pinpointed a paradoxical phenomenon wherein lung epithelial and myeloid cells mount an IL15 cytokine storm, and epithelial and NK cell senescence and apoptosis determine severity/fatality. Precise therapeutic goals could be formulated; these goals were met in high-dose SARS-CoV-2-challenged hamsters using either neutralizing antibodies that abrogate SARS-CoV-2•ACE2 engagement or a directly acting antiviral agent, EIDD-2801. IL15/IL15RA were elevated in the lungs of patients with fatal disease, and plasma levels of the cytokine prognosticated disease severity. INTERPRETATION: The ViP signatures provide a quantitative and qualitative framework for titrating the immune response in viral pandemics and may serve as a powerful unbiased tool to rapidly assess disease severity and vet candidate drugs. FUNDING: This work was supported by the National Institutes for Health (NIH) [grants CA151673 and GM138385 (to DS) and AI141630 (to P.G), DK107585-05S1 (SD) and AI155696 (to P.G, D.S and S.D), U19-AI142742 (to S. C, CCHI: Cooperative Centers for Human Immunology)]; Research Grants Program Office (RGPO) from the University of California Office of the President (UCOP) (R00RG2628 & R00RG2642 to P.G, D.S and S.D); the UC San Diego Sanford Stem Cell Clinical Center (to P.G, D.S and S.D); LJI Institutional Funds (to S.C); the VA San Diego Healthcare System Institutional funds (to L.C.A). GDK was supported through The American Association of Immunologists Intersect Fellowship Program for Computational Scientists and Immunologists. ONE SENTENCE SUMMARY: The host immune response in COVID-19.

Application of an evidence-based, out-patient treatment strategy for COVID-19: Multidisciplinary medical practice principles to prevent severe disease.

The COVID-19 pandemic has devastated individuals, families, and institutions throughout the world. Despite the breakneck speed of vaccine development, the human population remains at risk of further devastation. The decision to not become vaccinated, the protracted rollout of available vaccine, vaccine failure, mutational forms of the SARS virus, which may exhibit mounting resistance to our molecular strike at only one form of the viral family, and the rapid ability of the virus(es) to hitch a ride on our global transportation systems, means that we are will likely continue to confront an invisible, yet devastating foe. The enemy targets one of our human physiology's most important and vulnerable life-preserving body tissues, our broncho-alveolar gas exchange apparatus. Notwithstanding the fear and the fury of this microbe's potential to raise existential questions across the entire spectrum of human endeavor, the application of an early treatment intervention initiative may represent a crucial tool in our defensive strategy. This strategy is driven by evidence-based medical practice principles, those not likely to become antiquated, given the molecular diversity and mutational evolution of this very clever "world traveler".

Reversed-engineered human alveolar lung-on-a-chip model.

Here, we present a physiologically relevant model of the human pulmonary alveoli. This alveolar lung-on-a-chip platform is composed of a three-dimensional porous hydrogel made of gelatin methacryloyl with an inverse opal structure, bonded to a compartmentalized polydimethylsiloxane chip. The inverse opal hydrogel structure features well-defined, interconnected pores with high similarity to human alveolar sacs. By populating the sacs with primary human alveolar epithelial cells, functional epithelial monolayers are readily formed. Cyclic strain is integrated into the device to allow biomimetic breathing events of the alveolar lung, which, in addition, makes it possible to investigate pathological effects such as those incurred by cigarette smoking and severe acute respiratory syndrome coronavirus 2 pseudoviral infection. Our study demonstrates a unique method for reconstitution of the functional human pulmonary alveoli in vitro, which is anticipated to pave the way for investigating relevant physiological and pathological events in the human distal lung.

SARS-CoV-2 infection of primary human lung epithelium for COVID-19 modeling and drug discovery.

Coronavirus disease 2019 (COVID-19) is the latest respiratory pandemic caused by severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). Although infection initiates in the proximal airways, severe and sometimes fatal symptoms of the disease are caused by infection of the alveolar type 2 (AT2) cells of the distal lung and associated inflammation. In this study, we develop primary human lung epithelial infection models to understand initial responses of proximal and distal lung epithelium to SARS-CoV-2 infection. Differentiated air-liquid interface (ALI) cultures of proximal airway epithelium and alveosphere cultures of distal lung AT2 cells are readily infected by SARS-CoV-2, leading to an epithelial cell-autonomous proinflammatory response with increased expression of interferon signaling genes. Studies to validate the efficacy of selected candidate COVID-19 drugs confirm that remdesivir strongly suppresses viral infection/replication. We provide a relevant platform for study of COVID-19 pathobiology and for rapid drug screening against SARS-CoV-2 and emergent respiratory pathogens.

Heterogeneous groups of alveolar type II cells in lung homeostasis and repair.

Alveoli are the gas-exchanging units of the lung, and the alveolar barrier is often a key battleground where pathogens, allergens, and other insults from the environment are encountered. This is seen in the current coronavirus disease 2019 (COVID-19) pandemic, as alveolar epithelium is one of the major targets of SARS-COV-2, the virus that causes COVID-19. Thus, it is essential to understand the mechanisms in order to maintain the integrity of alveoli epithelium. Alveolar type II (AT2) cells behave as tissue stem cells that repair alveoli epithelium during steady-state replacement and after injury. However, not all AT2 cells are equal in their ability for self-renewal or differentiation. Through marker gene identification, lineage tracing, and single-cell RNA-sequencing (scRNA-seq), distinct subpopulations of AT2 cells have been identified that play the progenitor role in a different context. The revelation of AT2 heterogeneity has brought new insights into the role of AT2 cells in various lung disease settings and potentiates the finding of more therapeutics targets. In this mini review, we discuss the recently identified subpopulations of AT2 cells and their functions under steady-state, postinjury, and pathological conditions.

Part II. high-dose methotrexate with leucovorin rescue for severe COVID-19: An immune stabilization strategy for SARS-CoV-2 induced 'PANIC' attack.

Here, in Part II of a duology on the characterization and potential treatment for COVID-19, we characterize the application of an innovative treatment regimen for the prevention of the transition from mild to severe COVID-19, as well as detail an intensive immunotherapy intervention hypothesis. We propose as a putative randomized controlled trial that high-dose methotrexate with leucovorin (HDMTX-LR) rescue can abolish 'PANIC', thereby 'left-shifting' severe COVID-19 patients to the group majority of those infected with SARS-CoV-2, who are designated as having mild, even asymptomatic, disease. HDMTX-LR is endowed with broadly pleiotropic properties and is a repurposed, generic, inexpensive, and widely available agent which can be administered early in the course of severe COVID-19 thus rescuing the critical and irreplaceable gas-exchange alveoli. Further, we describe a preventative treatment intervention regimen for those designated as having mild to moderate COVID-19 disease, but who exhibit features which herald the transition to the severe variant of this disease. Both of our proposed hypothesis-driven questions should be urgently subjected to rigorous assessment in the context of randomized controlled trials, in order to confirm or refute the contention that the approaches characterized herein, are in fact capable of exerting mitigating, if not abolishing, effects upon SARS-CoV-2 triggered 'PANIC Attack'. Confirmation of our immunotherapy hypothesis would have far-reaching ramifications for the current pandemic, along with yielding invaluable lessons which could be leveraged to more effectively prepare for the next challenge to global health.

Part I. SARS-CoV-2 triggered 'PANIC' attack in severe COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic has produced a world-wide collapse of social and economic infrastructure, as well as constrained our freedom of movement. This respiratory tract infection is nefarious in how it targets the most distal and highly vulnerable aspect of the human bronchopulmonary tree, specifically, the delicate yet irreplaceable alveoli that are responsible for the loading of oxygen upon red cell hemoglobin for use by all of the body's tissues. In most symptomatic individuals, the disease is a mild immune-mediated syndrome, with limited damage to the lung tissues. About 20% of those affected experience a disease course characterized by a cataclysmic set of immune activation responses that can culminate in the diffuse and irreversible obliteration of the distal alveoli, leading to a virtual collapse of the gas-exchange apparatus. Here, in Part I of a duology on the characterization and potential treatment for COVID-19, we define severe COVID-19 as a consequence of the ability of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to trigger what we now designate for the first time as a 'Prolific Activation of a Network-Immune-Inflammatory Crisis', or 'PANIC' Attack, in the alveolar tree. In Part II we describe an immunotherapeutic hypothesis worthy of the organization of a randomized clinical trial in order to ascertain whether a repurposed, generic, inexpensive, and widely available agent is capable of abolishing 'PANIC'; thereby preventing or mitigating severe COVID-19, with monumental ramifications for world health, and the global pandemic that continues to threaten it.