Extracellular Vesicle Associated miRNAs Regulate Signaling Pathways Involved in COVID-19 Pneumonia and the Progression to Severe Acute Respiratory Corona Virus-2 Syndrome

BackgroundExtracellular vesicles (EVs) are mediators of cell-to-cell communication in inflammatory lung diseases. They function as carriers for miRNAs which regulate mRNA transcripts and signaling pathways after uptake into recipient cells. We investigated whether miRNAs associated with circulating EVs regulate immunologic processes in COVID-19.MethodsWe prospectively studied 20 symptomatic patients with COVID-19 pneumonia, 20 mechanically ventilated patients with severe COVID-19 (severe acute respiratory corona virus-2 syndrome, ARDS) and 20 healthy controls. EVs were isolated by precipitation, total RNA was extracted, profiled by small RNA sequencing and evaluated by differential gene expression analysis (DGE). Differentially regulated miRNAs between groups were bioinformatically analyzed, mRNA target transcripts identified and signaling networks constructed, thereby comparing COVID-19 pneumonia to the healthy state and pneumonia to severe COVID-19 ARDS.ResultsDGE revealed 43 significantly and differentially expressed miRNAs (25 downregulated) in COVID-19 pneumonia when compared to controls, and 20 miRNAs (15 downregulated) in COVID-19 ARDS patients in comparison to those with COVID-19 pneumonia. Network analysis for comparison of COVID-19 pneumonia to healthy controls showed upregulated miR-3168 (log2FC=2.28, padjusted<0.001), among others, targeting interleukin-6 (IL6) (25.1, 15.2 - 88.2 pg/ml in COVID-19 pneumonia) and OR52N2, an olfactory smell receptor in the nasal epithelium. In contrast, miR-3168 was significantly downregulated in COVID-19 ARDS (log2FC=-2.13, padjusted=0.003) and targeted interleukin-8 (CXCL8) in a completely activated network. Toll-like receptor 4 (TLR4) was inhibited in COVID-19 pneumonia by miR-146a-5p and upregulated in ARDS by let-7e-5p.ConclusionEV-derived miRNAs might have important regulative functions in the pathophysiology of COVID-19: CXCL8 regulates neutrophil recruitment into the lung causing epithelial damage whereas activated TLR4, to which SARS-CoV-2 spike protein binds strongly, increases cell surface ACE2 expression and destroys type II alveolar cells that secrete pulmonary surfactants; both resulting in pulmonary-capillary leakage and ARDS. These miRNAs may serve as biomarkers or as possible therapeutic targets.

Depletion of Numb and Numblike in Murine Lung Epithelial Cells Ameliorates Bleomycin-Induced Lung Fibrosis by Inhibiting the β-Catenin Signaling Pathway

Idiopathic pulmonary fibrosis (IPF) represents the most aggressive form of pulmonary fibrosis (PF) and is a highly debilitating disorder with a poorly understood etiology. The lung epithelium seems to play a critical role in the initiation and progression of the disease. A repeated injury of lung epithelial cells prompts type II alveolar cells to secrete pro-fibrotic cytokines, which induces differentiation of resident mesenchymal stem cells into myofibroblasts, thus promoting aberrant deposition of extracellular matrix (ECM) and formation of fibrotic lesions. Reactivation of developmental pathways such as the Wnt-β-catenin signaling cascade in lung epithelial cells plays a critical role in this process, but the underlying mechanisms are still enigmatic. Here, we demonstrate that the membrane-associated protein NUMB is required for pathological activation of β-catenin signaling in lung epithelial cells following bleomycin-induced injury. Importantly, depletion of Numb and Numblike reduces accumulation of fibrotic lesions, preserves lung functions, and increases survival rates after bleomycin treatment of mice. Mechanistically, we demonstrate that NUMB interacts with casein kinase 2 (CK2) and relies on CK2 to activate β-catenin signaling. We propose that pharmacological inhibition of NUMB signaling may represent an effective strategy for the development of novel therapeutic approaches against PF.

Pulmonary Alveolar Microlithiasis: A Unique Case of Familial PAM Complicated by Transplant Rejection

Background. Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterized by the deposition of calcium phosphate microliths or calcospherites, within the alveolar airspace. Typical imaging findings demonstrate a “sandstorm” appearance due to bilateral, interstitial sand-like micronodularities with basal predominance. Methods and Results. We describe an unusual case of a 48-year-old male with severe, familial PAM ultimately treated with a bilateral lung transplant. Conclusions. PAM is a rare lung disease caused by a mutation in the SLC34A2 gene, which encodes for a sodium-phosphate cotransporter in type II alveolar cells, leading to accumulation of intra-alveolar phosphate causing microlith formation. PAM has an indolent course but can progress to chronic hypoxic respiratory failure, ultimately requiring lung transplant, the only known effective treatment.

Type II alveolar cells with constitutive expression of MHCII and limited antigen presentation capacity contribute to improved respiratory viral disease outcomes

Type II alveolar cells (AT2s) are critical for basic respiratory homeostasis and tissue repair after lung injury. Prior studies indicate that AT2s also express major histocompatibility complex II (MHCII) molecules, but how MHCII expression by AT2s is regulated and how it contributes to host defense remain unclear. Here we show that AT2s express high levels of MHCII independent of conventional inflammatory stimuli, and that selective loss of MHCII from AT2s in mice results in the worsening of respiratory virus disease following influenza and Sendai virus infections. We also find that AT2s exhibit MHCII presentation capacity that is substantially limited in comparison to professional antigen presenting cells. The combination of constitutive MHCII expression and restrained presentation may position AT2s to contribute to lung adaptive immune responses in a measured fashion, without over-amplifying damaging inflammation.

Pathogenesis and Possible Drug Targets for Covid-19

Coronavirus (CoVs) is a large family of enveloped, single-stranded, positive-sense RNA viruses that infect a wide range of vertebrates. They are extensively found in bats and also in many other birds and mammals including humans. SARS-CoV-2 is a global pandemic and originated from Wuhan States of China. The SARS-CoV-2 is more genetically similar to zoonotic SARS-CoV and less similar to MERS-CoV. The viral surface spike protein of SARS-CoV-2 binds to the human angiotensin-converting enzyme-2 (ACE-2) receptor of Type II alveolar cells of the lungs and it appears to be the major portal of entry by this virus. The subsequent activation of the spike protein by transmembrane protease-2 and in addition to lung, ACE-2 is highly expressed in heart followed by kidney and intestinal epithelium. SARS-CoV-2 infects more men than women due to ACE-2 receptor on the cells increased with age and generally it was higher in men than in women. The incubation period for this virus varies from place to place and asystematic symptoms are also commonly seen in infected patients. There are a number of pharmaceuticals already being tried and are in different phase levels of testing, but a better understanding of the underlying pathobiology is required. In this circumstance, this article will briefly review the underlying principle for ACE-2 receptor as a specific target. Despite ACE-2 serving as the portal for infection, the role of ACE inhibitors or angiotensin receptor blockers requires further investigation.

COVID - 19 infection: Angiotensin II has a major role in the mortality rate. Low dose of inhaled Nitric oxide may be the treatment.

Since who characterized COVID-19 as a pandemic, all scientists and clinicians studied the viral effects on the various organs and tissues of the infected patients. The virus irreversible binding to the ACE2 in the target cell in the lungs is the first step of the viral deleterious pathway to invade the target tissues. As the virus replicates and its number increase, the ACE2 in lung type II alveolar cells become inactive. ACE2 is also located in the arterial and venous endothelial cells and arterial smooth muscle cells in most organs. ACE2 is the enzyme catalyzing the conversion of angiotensin II to angiotensin (1–7). The accumulated angiotensin II has a paracrine effect in the pulmonary system in increasing the mean pulmonary pressure and vasoconstriction affect the lungs. One of the suggested treatments is the use of low dose inhaled nitric oxide, which has minimal systemic effects. Treatment with low dose inhaled Nitric oxide can be done first to preserve the patient's condition and as a quick solution at first, and then inject him with angiotensin (1,7) for varying periods to maintain the rate of angiotensin II / angiotensin (1,7) which will provide two antagonists to the angiotensin II to decrease its effect on the infected tissue. In addition, this will increase the blood flow to the infected tissue, which will decrease the virus effect and will enhance the immune response. The nitric oxide usage will also increase the immune response, which will lower the infection period. Angiotensin (1,7) has anti - angiotensin II effect and should be used as a potential treatment.

COVID - 19 infection: the perspectives on Angiotensin II role

Since who characterized COVID-19 as a pandemic, all scientists and clinicians studied the viral effects on the various organs and tissues of the infected patients. The virus irreversible binding to the ACE2 in the target cell in the lungs is the first step of the viral deleterious pathway to invade the target tissues. As the virus replicates and its number increase, the ACE2 in lung type II alveolar cells become inactive. ACE2 is also located in the arterial and venous endothelial cells and arterial smooth muscle cells in most organs. ACE2 is the enzyme catalyzing the conversion of angiotensin II to angiotensin (1–7). Nitric oxide Should be tested as a potential treatment.

DENTAL CONSIDERATIONS AMIDST COVID-19 SCARE

A Novel coronavirus (2019-nCoV) identified in Wuhan city of china capable of causing life threatening respiratory illness declared as a pandemic by WHO and has become a global fear among the community and healthcare professionals in 2020. 2019-nCoV is a positive stranded RNA virus having an origin from bats targets the host cells via the enzyme Angiotensin Converting enzyme 2(ACE2), which is most abundant in the type II alveolar cells of the lungs. This virus has usual incubation period of approximate 5 days and typically spread from one person to another via respiratory droplets produced during coughing and sneezing. Spread of this virus in the community has been reported through direct transmission route such as cough, droplet transmission, aerosols, salivary route, ocular and through the contact spread. As the dental practice compels dentists to come in face to face contact with the patients and aerosols during certain dental procedures leading to the heightened risk of 2019-nCoV transmission from infected patients. We hereby make an attempt to discuss 2019-nCoV infection spread in the community and among dentist, including precautions and considerations pertaining to the practice of dentistry amidst 2019-nCoV scare.

Single-cell RNA expression profiling of ACE2, the receptor of SARS-CoV-2

A novel coronavirus SARS-CoV-2 was identified in Wuhan, Hubei Province, China in December of 2019. According to WHO report, this new coronavirus has resulted in 76,392 confirmed infections and 2,348 deaths in China by 22 February, 2020, with additional patients being identified in a rapidly growing number internationally. SARS-CoV-2 was reported to share the same receptor, Angiotensin-converting enzyme 2 (ACE2), with SARS-CoV. Here based on the public database and the state-of-the-art single-cell RNA-Seq technique, we analyzed the ACE2 RNA expression profile in the normal human lungs. The result indicates that the ACE2 virus receptor expression is concentrated in a small population of type II alveolar cells (AT2). Surprisingly, we found that this population of ACE2-expressing AT2 also highly expressed many other genes that positively regulating viral entry, reproduction and transmission. This study provides a biological background for the epidemic investigation of the COVID-19, and could be informative for future anti-ACE2 therapeutic strategy development.