Bronchial Epithelial Cells Promote the Differentiation of Th2 Lymphocytes in Airway Microenvironment through Jagged/Notch-1 Signaling after RSV Infection

Examining the contribution of Notch signaling to lung disease development

Notch pathway is a widely observed signaling system that holds pivotal functions in regulating various developmental cellular functions and operations. The Notch signaling mechanism is crucial for lung homeostasis, damage, and restoration. Based on increasing evidence, the Notch pathway has been identified, as critical for fibrosis and subsequently, the development of chronic fibroproliferative conditions in various organs and tissues. Recent research indicates that deregulation of Notch signaling correlates with the pathogenesis of significant pulmonary conditions, particularly chronic obstructive pulmonary disease (COPD), pulmonary fibrosis, asthma, pulmonary arterial hypertension (PAH), lung carcinoma, and pulmonary abnormalities in some hereditary disorders. In various cellular and tissue environments, and across both physiological and pathological conditions, multiple consequences of Notch activation have been observed. Studies have ascertained that the Notch signaling cascade exhibits close associations with various other signaling systems. This study provides an updated overview of Notch signaling's role, especially its link to fibrosis and its potential therapeutic implications. This study sheds light on the latest findings regarding the mechanisms and outcomes of irregular or lacking Notch activity in the onset and development of pulmonary diseases. As our insight into this signaling mechanism suggests that modulating Notch signaling might hold potential as a valuable additional therapeutic approach in upcoming research.

How early life respiratory viral infections impact airway epithelial development and may lead to asthma

Childhood asthma is a common chronic disease of the airways that results from host and environment interactions. Most risk factor studies of asthma point to the first year of life as a susceptibility window of mucosal exposure that directly impacts the airway epithelium and airway epithelial cell development. The development of the airway epithelium, which forms a competent barrier resulting from coordinated interactions of different specialized cell subsets, occurs during a critical time frame in normal postnatal development in the first year of life. Understanding the normal and aberrant developmental trajectory of airway epithelial cells is important in identifying pathways that may contribute to barrier dysfunction and asthma pathogenesis. Respiratory viruses make first contact with and infect the airway mucosa. Human rhinovirus (HRV) and respiratory syncytial virus (RSV) are mucosal pathogens that are consistently identified as asthma risk factors. Respiratory viruses represent a unique early life exposure, different from passive irritant exposures which injure the developing airway epithelium. To replicate, respiratory viruses take over the host cell transcriptional and translational processes and exploit host cell energy metabolism. This takeover impacts the development and differentiation processes of airway epithelial cells. Therefore, delineating the mechanisms through which early life respiratory viral infections alter airway epithelial cell development will allow us to understand the maturation and heterogeneity of asthma and develop tools tailored to prevent disease in specific children. This review will summarize what is understood about the impact of early life respiratory viruses on the developing airway epithelium and define critical gaps in our knowledge.

Expert consensus on the diagnosis, treatment, and prevention of respiratory syncytial virus infections in children

BACKGROUND

Respiratory syncytial virus (RSV) is the leading global cause of respiratory infections and is responsible for about 3 million hospitalizations and more than 100,000 deaths annually in children younger than 5 years, representing a major global healthcare burden. There is a great unmet need for new agents and universal strategies to prevent RSV infections in early life. A multidisciplinary consensus development group comprising experts in epidemiology, infectious diseases, respiratory medicine, and methodology aims to develop the current consensus to address clinical issues of RSV infections in children.

DATA SOURCES

The evidence searches and reviews were conducted using electronic databases, including PubMed, Embase, Web of Science, and the Cochrane Library, using variations in terms for "respiratory syncytial virus", "RSV", "lower respiratory tract infection", "bronchiolitis", "acute", "viral pneumonia", "neonatal", "infant" "children", and "pediatric".

RESULTS

Evidence-based recommendations regarding diagnosis, treatment, and prevention were proposed with a high degree of consensus. Although supportive care remains the cornerstone for the management of RSV infections, new monoclonal antibodies, vaccines, drug therapies, and viral surveillance techniques are being rolled out.

CONCLUSIONS

This consensus, based on international and national scientific evidence, reinforces the current recommendations and integrates the recent advances for optimal care and prevention of RSV infections. Further improvements in the management of RSV infections will require generating the highest quality of evidence through rigorously designed studies that possess little bias and sufficient capacity to identify clinically meaningful end points.

Multiplex Quantitative Analysis of 9 Compounds of Scutellaria baicalensis Georgi in the Plasma of Respiratory Syncytial Virus-Infected Mice Based on HPLC-MS/MS and Pharmacodynamic Effect Correlation Analysis

According to traditional Chinese medicine, Scutellaria baicalensis Georgi possesses the therapeutic properties of heat-clearing, dampness-drying, diarrhea alleviation, and detoxification, making it a clinically used remedy for respiratory infections. The objective of this study was to investigate the changes in constituent content, pharmacodynamic effects, and material basis of Scutellaria baicalensis Georgi in the plasma of mice infected with respiratory syncytial virus (RSV). The results showed that a sensitive and efficient high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method was established in this study. Multiple quantitative analyses of Baicalein, Apigenin-7-glucuronide, Baicalin, Oroxylin A 7-O-beta-d-glucuronide, Wogonoside, Norwogonin, Wogonin, Chrysin, and Oroxylin A in mouse plasma revealed a bimodal absorption phenomenon within the time frame of 0.167 h to 6 h post-administration, with the exception of chrysin. Following 6 h of administration, the concentrations of 9 components continued to decrease until they became undetectable. In comparison to the model group, all administered groups exhibited significant reductions in lung index and viral load, with their lung index repair rate and viral suppression rate aligning with the blood concentration-time curve. Finally, through the application of the gray correlation analysis method, we identified Baicalein, Baicalin, Oroxylin A 7-O-beta-d-glucuronide, Wogonoside, Norwogonin, and Wogonin as potential pharmacodynamic material bases of Scutellaria baicalensis Georgi against RSV infection.

Alveolar macrophages and airway hyperresponsiveness associated with respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is a ubiquitous pathogen of viral bronchiolitis and pneumonia in children younger than 2 years of age, which is closely associated with recurrent wheezing and airway hyperresponsiveness (AHR). Alveolar macrophages (AMs) located on the surface of the alveoli cavity are the important innate immune barrier in the respiratory tract. AMs are recognized as recruited airspace macrophages (RecAMs) and resident airspace macrophages (RAMs) based on their origins and roaming traits. AMs are polarized in the case of RSV infection, forming two macrophage phenotypes termed as M1-like and M2-like macrophages. Both M1 macrophages and M2 macrophages are involved in the modulation of inflammatory responses, among which M1 macrophages are capable of pro-inflammatory responses and M2 macrophages are capable of anti-proinflammatory responses and repair damaged tissues in the acute and convalescent phases of RSV infection. Polarized AMs affect disease progression through the alteration of immune cell surface phenotypes as well as participate in the regulation of T lymphocyte differentiation and the type of inflammatory response, which are closely associated with long-term AHR. In recent years, some progress have been made in the regulatory mechanism of AM polarization caused by RSV infection, which participates in acute respiratory inflammatory response and mediating AHR in infants. Here we summarized the role of RSV-infection-mediated AM polarization associated with AHR in infants.

Assemblies of JAG1 and JAG2 determine tracheobronchial cell fate in mucosecretory lung disease

Mucosecretory lung disease compromises airway epithelial function and is characterized by goblet cell hyperplasia and ciliated cell hypoplasia. Goblet and ciliated cell types are derived from tracheobronchial stem/progenitor cells via a Notch-dependent mechanism. Although specific arrays of Notch receptors regulate cell fate determination, the function of the ligands Jagged1 (JAG1) and JAG2 is unclear. This study examined JAG1 and JAG2 function using human air-liquid-interface cultures that were treated with γ-secretase complex (GSC) inhibitors, neutralizing peptides/antibodies, or WNT/β-catenin pathway antagonists/agonists. These experiments revealed that JAG1 and JAG2 regulated cell fate determination in the tracheobronchial epithelium; however, their roles did not adhere to simple necessity and sufficiency rules. Biochemical studies indicated that JAG1 and JAG2 underwent posttranslational modifications that resulted in generation of a JAG1 C-terminal peptide and regulated the abundance of full-length JAG2 on the cell surface. GSC and glycogen synthase kinase 3 were implicated in these posttranslational events, but WNT agonist/antagonist studies and RNA-Seq indicated a WNT-independent mechanism. Collectively, these data suggest that posttranslational modifications create distinct assemblies of JAG1 and JAG2, which regulate Notch signal strength and determine the fate of tracheobronchial stem/progenitor cells.

The Recombinant Eg.P29-Mediated miR-126a-5p Promotes the Differentiation of Mouse Naive CD4+ T Cells via DLK1-Mediated Notch1 Signal Pathway

Cystic echinococcosis (CE) is a zoonotic parasitic disease spread worldwide caused by Echinococcus granulosus (Eg), which sometimes causes serious damage; however, in many cases, people are not aware that they are infected. A number of recombinant vaccines based on Eg are used to evaluate their effectiveness against the infection. Our previous report showed that recombinant Eg.P29 (rEg.P29) has a marvelous immunoprotection and can induce Th1 immune response. Furthermore, data of miRNA microarray in mice spleen CD4⁺ T cells showed that miR-126a-5p was significantly elevated 1 week after immunization by using rEg.P29. Therefore, in this perspective, we discussed the role of miR-126a-5p in the differentiation of naive CD4⁺ T cells into Th1/Th2 under rEg.P29 immunization and determined the mechanisms associated with delta-like 1 homolog (DLK1) and Notch1 signaling pathway. One week after P29 immunization of mice, we found that miR-126a-5p was significantly increased and DLK1 expression was decreased, while Notch1 pathway activation was enhanced and Th1 response was significantly stronger. The identical conclusion was obtained by overexpression of mmu-miR-126a-5p in primary naive CD4⁺ T cells in mice. Intriguingly, mmu-miR-126a-5p was significantly raised in serum from mice infected with protoscolex in the early stages of infection and markedly declined in the late stages of infection, while has-miR-126-5p expression was dramatically reduced in serum from CE patients. Taken together, we show that miR-126a-5p functions as a positive regulator of Notch1-mediated differentiation of CD4⁺ T cells into Th1 through downregulating DLK1 in vivo and in vitro. Hsa-miR-126-5p is potentially a very promising diagnostic biomarker for CE.

RSV Promotes Epithelial Neuroendocrine Phenotype Differentiation through NODAL Signaling Pathway

Background

Respiratory syncytial virus (RSV) infects infants and children, predisposing them to development of asthma during adulthood. Epithelial neuroendocrine phenotypes may be associated with development of asthma. This study hopes to ascertain if RSV infection promotes epithelial neuroendocrine phenotypes through the NODAL signaling pathway.

Methods

The GSE6802 data set was obtained from the GEO database, and the differential genes were analyzed using the R language. An in vitro model was constructed with RSV infected human respiratory epithelial cells, and then real-time qPCR and immunofluorescence were used to detect the expression of different epithelial biomarkers and airway neuropeptides. The acute and chronic infection model of RSV infection was established by intranasal injection of RSV into guinea pigs. Immunohistochemistry and Western blot were used to detect the expression of pulmonary neuroendocrine cells markers ENO2 and neuropeptides.

Results

The expression levels of ENO2, SP, CGRP, and NODAL/ACTRII were significantly higher in the RSV infection group than those of the control group, which were abrogated by siRNA-NODAL. In vivo, we found that the expression levels of ENO2, SP, and CGRP were significantly higher than that of the control group.

Conclusion

RSV promotes epithelial neuroendocrine phenotypes through the NODAL signaling pathway.

Oral administration of Clostridium butyricum rescues streptomycin-exacerbated respiratory syncytial virus-induced lung inflammation in mice

Changes in the intestinal microbiota indirectly impact the health of mucosa distal to the intestine, particularly the respiratory tract. However, the effects of intestinal microbiota dysbiosis on the regulation of respiratory syncytial virus (RSV) infection are not clear. In this study, we examined the effects of altering the intestinal microbiota on the pulmonary immune response against RSV infection. BALB/c mice were treated with streptomycin before infection with RSV to study the altered immune response. The ingestion of streptomycin led to a marked alteration in the intestinal microbiota with a reduced abundance of Lactobacillus and Clostridium genera, followed by greatly aggravated pulmonary inflammation in response to RSV infection. This aggravated inflammation was associated with a dysregulated immune response against RSV infection, characterized by the increased expression of IFN-γ and IL-17 and increased pulmonary M1-like macrophage polarization, and decreased expression of IL-5. Supplementation of Clostridium butyricum (CB) prevented aggravated inflammation and the dysregulated immune response characterized by greater M2 polarization of pulmonary macrophages and decreased release of IFN-γ and IL-17 as well as increased IL-5 levels. Furthermore, in vitro and in vivo experiments identified that butyrate, the main metabolite produced by CB, promoted M2 polarization of macrophages in RSV-infected mice exposed to streptomycin. Together, these results demonstrate the mechanism by which intestinal microbiota modulate the pulmonary immune response to RSV infection.

Evidence of a dysregulated vitamin D endocrine system in SARS-CoV-2 infected patient's lung cells

Although a defective vitamin D endocrine system has been widely suspected to be associated in SARS-CoV-2 pathobiology, the status of the vitamin D endocrine system and vitamin D-modulated genes in lung cells of patients infected with SARS-CoV-2 remains unknown. To understand the significance of the vitamin D endocrine system in SARS-CoV-2 pathobiology, computational approaches were applied to transcriptomic datasets from bronchoalveolar lavage fluid (BALF) cells of such patients or healthy individuals. Levels of vitamin D receptor, retinoid X receptor, and CYP27A1 in BALF cells of patients infected with SARS-CoV-2 were found to be reduced. Additionally, 107 differentially expressed, predominantly downregulated genes, as potentially modulated by vitamin D endocrine system, were identified in transcriptomic datasets from patient's cells. Further analysis of differentially expressed genes provided eight novel genes with a conserved motif with vitamin D-responsive elements, implying the role of both direct and indirect mechanisms of gene expression by the dysregulated vitamin D endocrine system in SARS-CoV-2-infected cells. Protein-protein interaction network of differentially expressed vitamin D-modulated genes were enriched in the immune system, NF-κB/cytokine signaling, and cell cycle regulation as top predicted pathways that might be affected in the cells of such patients. In brief, the results presented here povide computational evidence to implicate a dysregulated vitamin D endocrine system in the pathobiology of SARS-CoV-2 infection.

Innate Immune Components that Regulate the Pathogenesis and Resolution of hRSV and hMPV Infections

The human respiratory syncytial virus (hRSV) and human Metapneumovirus (hMPV) are two of the leading etiological agents of acute lower respiratory tract infections, which constitute the main cause of mortality in infants. However, there are currently approved vaccines for neither hRSV nor hMPV. Moreover, despite the similarity between the pathology caused by both viruses, the immune response elicited by the host is different in each case. In this review, we discuss how dendritic cells, alveolar macrophages, neutrophils, eosinophils, natural killer cells, innate lymphoid cells, and the complement system regulate both pathogenesis and the resolution of hRSV and hMPV infections. The roles that these cells play during infections by either of these viruses will help us to better understand the illnesses they cause. We also discuss several controversial findings, relative to some of these innate immune components. To better understand the inflammation in the lungs, the role of the respiratory epithelium in the recruitment of innate immune cells is briefly discussed. Finally, we review the main prophylactic strategies and current vaccine candidates against both hRSV and hMPV.

CARsomes inhibit airway allergic inflammation in mice by inducing antigen-specific Th2 cell apoptosis

BACKGROUND

Skewed T helper (Th)2 response plays a crucial role in the pathogenesis of allergic diseases. The therapeutic efficacy for allergic diseases is unsatisfactory currently. This study aims to regulate the skewed Th2 response with CARsomes.

METHODS

The CARsome consisted of an epitope of Dermatophagoides farina-1 (Derf1), a segment of the anti-DEC205 antibody, the scFv, and an open reading frame of perforin. This fusion protein binds to DEC205 molecule on the surface of exosomes derived from dendritic cells (DC). The effects of CARsome on inducing antigen (Ag)-specific Th2 cell apoptosis were assessed both in vivo and in vitro.

RESULTS

Exposure to CARsomes in the culture induced Ag-specific Th2 cell apoptosis. Injection of CARsomes through the vein puncture also induced Ag-specific Th2 cell apoptosis in the lungs of sensitized mice. CARsomes could induce Ag-specific regulatory T cells. Administration of CARsomes efficiently inhibited experimental allergic airway inflammation.

CONCLUSIONS

The CARsomes can inhibit allergic airway inflammation by inducing Ag-specific Th2 cell apoptosis and induce Ag-specific regulatory T cells. The data suggest that CARsomes have the translational potential to be used to treat allergic airway inflammation.

Unbiased analysis of peripheral blood mononuclear cells reveals CD4 T cell response to RSV matrix protein

Respiratory syncytial virus (RSV) is the most important cause of respiratory tract illness especially in young infants that develop severe disease requiring hospitalization, and accounting for 74,000–126,000 admissions in the United States (Rezaee et al., 2017; Resch, 2017). Observations of neonatal and infant T cells suggest that they may express different immune markers compared to T-cells from older children. Flow cytometry analysis of cellular responses using “conventional” anti-viral markers (IL2, IFN-γ, TNF, IL10 and IL4) upon RSV-peptide stimulation detected an overall low RSV response in peripheral blood. Therefore we sought an unbiased approach to identify RSV-specific immune markers using RNA-sequencing upon stimulation of infant PBMCs with overlapping peptides representing RSV antigens. To understand the cellular response using transcriptional signatures, transcription factors and cell-type specific signatures were used to investigate breadth of response across peptides. Unexpected from the ICS data, M peptide induced a response equivalent to the F-peptide and was characterized by activation of GATA2, 3, STAT3 and IRF1. This along with upregulation of several unconventional T cell signatures was only observed upon M-peptide stimulation. Moreover, signatures of natural RSV infections were identified from the data available in the public domain to investigate similarities between transcriptional signatures from PBMCs and upon peptide stimulation. This analysis also suggested activation of T cell response upon M-peptide stimulation. Hence, based on transcriptional response, markers were chosen to validate the role of M-peptide in activation of T cells. Indeed, CD4+CXCL9+ cells were identified upon M-peptide stimulation by flow cytometry. Future work using additional markers identified in this study could reveal additional unconventional T cells responding to RSV infections in infants. In conclusion, T cell responses to RSV in infants may not follow the canonical Th1/Th2 patterns of effector responses but include additional functions that may be unique to the neonatal period and correlate with clinical outcomes.

COVID-19 in the heart and the lungs: could we "Notch" the inflammatory storm?

From January 2020, coronavirus disease (COVID-19) originated in China has spread around the world. The disease is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The presence of myocarditis, cardiac arrest, and acute heart failure in COVID-19 patients suggests the existence of a relationship between SARS-CoV-2 infection and cardiac disease. The Notch signalling is a major regulator of cardiovascular function and it is also implicated in several biological processes mediating viral infections. In this report we discuss the possibility to target Notch signalling to prevent SARS-CoV-2 infection and interfere with the progression of COVID-19- associated heart and lungs disease.

Suppressive effects of S100A8 and S100A9 on neutrophil apoptosis by cytokine release of human bronchial epithelial cells in asthma

S100A8 and S100A9 are important proteins in the pathogenesis of allergy. Asthma is an allergic lung disease, characterized by bronchial inflammation due to leukocytes, bronchoconstriction, and allergen-specific IgE. In this study, we examined the role of S100A8 and S100A9 in the interaction of cytokine release from bronchial epithelial cells, with constitutive apoptosis of neutrophils. S100A8 and S100A9 induce increased secretion of neutrophil survival cytokines such as MCP-1, IL-6 and IL-8. This secretion is suppressed by TLR4 inhibitor), LY294002, AKT inhibitor, PD98059, SB202190, SP600125, and BAY-11-7085. S100A8 and S100A9 also induce the phosphorylation of AKT, ERK, p38 MAPK and JNK, and activation of NF-κB, which were blocked after exposure to TLR4i, LY294002, AKTi, PD98059, SB202190 or SP600125. Furthermore, supernatants collected from bronchial epithelial cells after S100A8 and S100A9 stimulation suppressed the apoptosis of normal and asthmatic neutrophils. These inhibitory mechanisms are involved in suppression of caspase 9 and caspase 3 activation, and BAX expression. The degradation of MCL-1 and BCL-2 was also blocked by S100A8 and S100A9 stimulation. Essentially, neutrophil apoptosis was blocked by co-culture of normal and asthmatic neutrophils with BEAS-2B cells in the presence of S100A8 and S100A9. These findings will enable elucidation of asthma pathogenesis.

Allergy and Atopic Diseases: An Update on Experimental Evidence

Over the last decades, an increasing appearance of allergies and atopic disorders, such as asthma, dermatitis, and rhinitis, has been observed. The mechanisms of these disorders remain unclear, and therefore the development of novel therapies is limited. Current treatments are often symptomatic, nonspecific, or may have severe side effects. Further insights into the mechanisms of the underlying disease pathogenesis could reveal novel targets for treatment. In this review, we provide an update on recent basic and translational studies that offer novel insights and opportunities for the treatment of patients with atopic disorders.

Effects of combination of mizolastine and proteoglycan on chronic urticaria: a randomized controlled trial

The present study aimed to observe the therapeutic effect of combined mizolastine and proteoglycan in chronic urticaria. The patients were randomly divided into the treatment group (n = 56) and the control group (n = 44). The treatment group was medicated with calcium gluconate (10 mg/ time, 1 time/day), vitamin D3 (intramuscular 10 mg/time, 1 time/week), mizolastine (10 mg/time, 1 time/day), and proteoglycan (1.2 g/time, 3 times/day), while the control group was administered with the same drugs except proteoglycan for 4 weeks. After treatment with combined mizolastine and proteoglycan, therapeutic effect with symptoms decline index (SDI) more than 60% was significant different (44 vs. 24, p = 0.000973) and the relapse rate after 2 months was significantly lower (17.9% vs. 38.6%, p = 0.0202). Using ELISA, we found that the IFN-γ (37.88 ± 4.27 pg/mL vs. 21.91 ± 4.95 pg/mL, p = 0.028) levels were specifically increased in the experiment group. The combination of mizolastine plus proteoglycan is effective in treating chronic urticaria with better therapeutic effect and lower relapse rate through promoting IFN-γ production.