The role of Th17 and Treg responses in the pathogenesis of RSV infection

Immune Response to Respiratory Viral Infections

The respiratory system is constantly exposed to viral infections that are responsible for mild to severe diseases. In this narrative review, we focalized the attention on respiratory syncytial virus (RSV), influenza virus, and severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infections, responsible for high morbidity and mortality in the last decades. We reviewed the human innate and adaptive immune responses in the airways following infection, focusing on a particular population: newborns and pregnant women. The recent Coronavirus disease-2019 (COVID-19) pandemic has highlighted how our interest in viral pathologies must not decrease. Furthermore, we must increase our knowledge of infection mechanisms to improve our future defense strategies.

The imbalance of pulmonary Th17/Treg cells in BALB/c suckling mice infected with respiratory syncytial virus-mediated intestinal immune damage and gut microbiota changes

The immune response induced by respiratory syncytial virus (RSV) infection is closely related to changes in the composition and function of gastrointestinal microorganisms. However, the specific mechanism remains unknown and the pulmonary-intestinal axis deserves further study. In this study, the mRNA levels of ROR-γt and Foxp3 in the lung and intestine increased first and then decreased. IL-17 and IL-22 reached the maximum on the third day after infection in the lung, and on the second day after infection in the small intestine and colon, respectively. RegⅢγ in intestinal tissue reached the maximum on the third day after RSV infection. Moreover, the genus enriched in the RSV group was Aggregatibacter, and Proteus was reduced. RSV infection not only causes Th17/Treg cell imbalance in the lungs of mice but also leads to the release of excessive IL-22 from the lungs through blood circulation which binds to IL-22 receptors on the intestinal surface, inducing RegⅢγ overexpression, impaired intestinal Th17/Treg development, and altered gut microbiota composition. Our research reveals a significant link between the pulmonary and intestinal axis after RSV infection.

IMPORTANCE

RSV is the most common pathogen causing acute lower respiratory tract infections in infants and young children, but the complex interactions between the immune system and gut microbiota induced by RSV infection still requires further research. In this study, it was suggested that RSV infection in 7-day-old BALB/c suckling mice caused lung inflammation and disruption of Th17/Treg cells development, and altered the composition of gut microbiota through IL-22 induced overexpression of RegⅢγ, leading to intestinal immune injury and disruption of gut microbiota. This research reveals that IL-22 may be the link between the lung and gut. This study may provide a new insight into the intestinal symptoms caused by RSV and other respiratory viruses and the connection between the lung and gut axis, as well as new therapeutic ideas for the treatment of RSV-infected children.

Chitinase 3-like 1 plays a pivotal role in airway response of RSV infection via regulating DC functional transition

BACKGROUND

Dendritic cells (DCs) contribute to immune imbalance and airway hyperresponsiveness (AHR) induced by respiratory syncytial virus (RSV). The aim of present study was to explore the mechanism of RSV regulating naive T cell differentiation through DCs.

METHODS

We generated a Lentivirus shRNA expression vector to knock down CHI3L1 in mouse lungs and bone marrow-derived dendritic cells (BMDCs). Then we investigated the effect of CHI3L1 knockdown on MAPK/ERK pathway, PI3K/AKT pathway, mature DCs represented by molecular markers, naive T cell differentiation and related cytokine expression in vitro and in vivo models of RSV.

RESULTS

RSV elevated CHI3L1 expression in lung DCs and BMDCs. Knockdown of CHI3L1 impeded RSV-induced activation of MAPK/ERK and PI3K/AKT signaling pathways, attenuated CD86 and OX40L expression in mature DCs, reduced the proportion of Th2 and Th17 cells, and increased the proportion of Treg cells. In addition, by blocking CHI3L1, RSV-infected mice shown relief of airway resistance, the downregulation of Th2/Th17 like cytokines IL-4, IL-13 and IL-17 levels, and the upregulation of IL-10.

CONCLUSION

Our data show that CHI3L1 promotes RSV induced immune imbalance and airway hyperresponsiveness by regulating the functional transformation of DCs.

Regulatory T cells in lung disease and transplantation

Pulmonary disease can refer to the disease of the lung itself or the pulmonary manifestations of systemic diseases, which are often connected to the malfunction of the immune system. Regulatory T (Treg) cells have been shown to be important in maintaining immune homeostasis and preventing inflammatory damage, including lung diseases. Given the increasing amount of evidence linking Treg cells to various pulmonary conditions, Treg cells might serve as a therapeutic strategy for the treatment of lung diseases and potentially promote lung transplant tolerance. The most potent and well-defined Treg cells are Foxp3-expressing CD4+ Treg cells, which contribute to the prevention of autoimmune lung diseases and the promotion of lung transplant rejection. The protective mechanisms of Treg cells in lung disease and transplantation involve multiple immune suppression mechanisms. This review summarizes the development, phenotype and function of CD4+Foxp3+ Treg cells. Then, we focus on the therapeutic potential of Treg cells in preventing lung disease and limiting lung transplant rejection. Furthermore, we discussed the possibility of Treg cell utilization in clinical applications. This will provide an overview of current research advances in Treg cells and their relevant application in clinics.

Increased blood immune regulatory cells in severe COVID-19 with autoantibodies to type I interferons

The hallmark of severe COVID-19 is an uncontrolled inflammatory response, resulting from poorly understood immunological dysfunction. While regulatory T (Treg) and B (Breg) cells, as the main elements of immune homeostasis, contribute to the control of hyperinflammation during COVID-19 infection, we hypothesized change in their levels in relation to disease severity and the presence of autoantibodies (auto-Abs) to type I IFNs. Cytometric analysis of blood of 62 COVID-19 patients with different severities revealed an increased proportion of conventional (cTreg; CD25+FoxP3+) and unconventional (uTreg; CD25-FoxP3+) Tregs, as well as the LAG3+ immune suppressive form of cTreg/uTreg, in the blood of severe COVID-19 cases compared to the milder, non-hospitalized cases. The increase in blood levels of cTreg/uTreg, but not LAG3+ cTreg/uTreg subtypes, was even higher among patients with severe COVID-19 and auto-Abs to type I IFNs. Regarding Bregs, compared to the milder, non-hospitalized cases, the proportion of IL-35+ and IL-10+ Bregs was elevated in the blood of severe COVID-19 patients, and to a higher extent in those with auto-Abs to type I IFNs. Moreover, blood levels of cTreg, LAG3+ cTreg/uTreg, and IL-35+ and IL-10+ Breg subtypes were associated with lower blood levels of proinflammatory cytokines such as IL-6, IL-17, TNFα, and IL-1β. Interestingly, patients who were treated with either tocilizumab and/or a high dose of Vitamin D had higher blood levels of these regulatory cells and better control of the proinflammatory cytokines. These observations suggest that perturbations in the levels of immunomodulatory Tregs and Bregs occur in COVID-19, especially in the presence of auto-Abs to type I IFNs.

IgGκ Signal Peptide Enhances the Efficacy of an Influenza Vector Vaccine against Respiratory Syncytial Virus Infection in Mice

Intranasal vaccination using influenza vectors is a promising approach to developing vaccines against respiratory pathogens due to the activation of the mucosa-associated immune response. However, there is no clear evidence of a vector design that could be considered preferable. To find the optimal structure of an influenza vector with a modified NS genomic segment, we constructed four vector expressing identical transgene sequences inherited from the F protein of the respiratory syncytial virus (RSV). Two vectors were designed aiming at transgene accumulation in the cytosol. Another two were supplemented with an IgGκ signal peptide prior to the transgene for its extracellular delivery. Surprisingly, adding the IgGκ substantially enhanced the T-cell immune response to the CD8 epitope of the transgene. Moreover, this strategy allowed us to obtain a better protection of mice from the RSV challenge after a single intranasal immunization. Protection was achieved without antibodies, mediated by a balanced T-cell immune response including the formation of the RSV specific effector CD8+ IFNγ+/IL10+-producing cells and the accumulation of Treg cells preventing immunopathology in the lungs of infected mice. In addition to the presented method for optimizing the influenza vector, our results highlight the possibility of achieving protection against RSV through a respiratory-associated T-cell immune response alone.

Risk Factors Associated with Severe RSV Infection in Infants: What Is the Role of Viral Co-Infections?

The respiratory syncytial virus (RSV) represents the leading cause of viral lower respiratory tract infections (LRTI) in children worldwide and is associated with significant morbidity and mortality rates. The clinical picture of an RSV infection differs substantially between patients, and the role of viral co-infections is poorly investigated. During two consecutive winter seasons from October 2018 until February 2020, we prospectively included children up to 2 years old presenting with an acute LRTI, both ambulatory and hospitalized. We collected clinical data and tested nasopharyngeal secretions for a panel of 16 different respiratory viruses with multiplex RT-qPCR. Disease severity was assessed with traditional clinical parameters and scoring systems. A total of 120 patients were included, of which 91.7% were RSV positive; 42.5% of RSV-positive patients had a co-infection with at least one other respiratory virus. We found that patients suffering from a single RSV infection had higher pediatric intensive care unit (PICU) admission rates (OR = 5.9, 95% CI = 1.53 to 22.74), longer duration of hospitalization (IRR = 1.25, 95% CI = 1.03 to 1.52), and a higher Bronchiolitis Risk of Admission Score (BRAS) (IRR = 1.31, 95% CI = 1.02 to 1.70) compared to patients with RSV co-infections. No significant difference was found in saturation on admission, O2 need, or ReSViNET-score. In our cohort, patients with a single RSV infection had increased disease severity compared to patients with RSV co-infections. This suggests that the presence of viral co-infections might influence the course of RSV bronchiolitis, but heterogeneity and small sample size in our study prevents us from drawing strong conclusions. IMPORTANCE RSV is worldwide the leading cause of serious airway infections. Up to 90% of children will be infected by the age of 2. RSV symptoms are mostly mild and typically mimic a common cold in older children and adolescents, but younger children can develop severe lower respiratory tract disease, and currently it is unclear why certain children develop severe disease while others do not. In this study, we found that children with a single RSV infection had a higher disease severity compared to patients with viral co-infections, suggesting that the presence of a viral co-infection could influence the course of an RSV bronchiolitis. As preventive and therapeutic options for RSV-associated disease are currently limited, this finding could potentially guide physicians to decide which patients might benefit from current or future treatment options early in the course of disease, and therefore, warrants further investigation.

Mucosal Vaccination with Live Attenuated Bordetella bronchiseptica Protects against Challenge in Wistar Rats

Bordetella bronchiseptica (Bb) is a Gram-negative bacterium responsible for canine infectious respiratory disease complex (CIRDC). Several vaccines targeting this pathogen are currently licensed for use in dogs, but their mechanism of action and the correlates of protection are not fully understood. To investigate this, we used a rat model to examine the immune responses induced and the protection conferred by a canine mucosal vaccine after challenge. Wistar rats were vaccinated orally or intranasally on D0 and D21 with a live attenuated Bb vaccine strain. At D35, the rats of all groups were inoculated with 10³ CFU of a pathogenic strain of B. bronchiseptica. Animals vaccinated via either the intranasal or the oral route had Bb-specific IgG and IgM in their serum and Bb-specific IgA in nasal lavages. Bacterial load in the trachea, lung, and nasal lavages was lower in vaccinated animals than in non-vaccinated control animals. Interestingly, coughing improved in the group vaccinated intranasally, but not in the orally vaccinated or control group. These results suggest that mucosal vaccination can induce mucosal immune responses and provide protection against a Bb challenge. This study also highlights the advantages of a rat model as a tool for studying candidate vaccines and routes of administration for dogs.

Gut microbiota induces hepatic steatosis by modulating the T cells balance in high fructose diet mice

Metabolic diseases are often associated with high fructose (HF) consumption. HF has also been found to alter the gut microbiota, which then favors the development of nonalcoholic fatty liver disease. However, the mechanisms underlying of the gut microbiota on this metabolic disturbance are yet to be determined. Thus, in this study, we further explored the effect the gut microbiota concerning the T cells balance in an HF diet mouse model. We fed mice 60% fructose-enriched diet for 12 weeks. At 4 weeks, HF diet did not affect the liver, but it caused injury to the intestine and adipose tissues. After 12 weeks, the lipid droplet aggregation was markedly increased in the liver of HF-fed mice. Further analysis of the gut microbial composition showed that HF decreased the Bacteroidetes/Firmicutes ratio and increased the levels of Blautia, Lachnoclostridium, and Oscillibacter. In addition, HF can increase the expression of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in the serum. T helper type 1 cells were significantly increased, and regulatory T(Treg) cells were markedly decreased in the mesenteric lymph nodes of the HF-fed mice. Furthermore, fecal microbiota transplantation alleviates systemic metabolic disorder by maintaining liver and intestinal immune homeostasis. Overall, our data indicated that intestinal structure injury and intestinal inflammation might be early, and liver inflammation and hepatic steatosis may be a subsequent effect following HF diets. Gut microbiota disorders impairing the intestinal barrier function and triggering immune homeostasis imbalance may be an importantly responsible for long-term HF diets induced hepatic steatosis.

Clinical characteristics and differential cytokine expression in hospitalized Taiwanese children with respiratory syncytial virus and rhinovirus bronchiolitis

BACKGROUND

Viral bronchiolitis presents a heterogeneous spectrum. In this study, we investigated the clinical characteristics and the cytokines/chemokines profiles among respiratory syncytial virus (RSV), rhinovirus (RV), and their dual infection in Taiwanese children with viral bronchiolitis.

METHOD

This study was conducted between October 2014 and June 2017. Viral etiology was identified using a Luminex respiratory virus panel and blood cytokines were evaluated using a MILLIPLEX MAP Human Cytokine/Chemokine Panel. Cytokine/Chemokine expressions were compared by clinical severity, steroid treatment, and viral entities.

RESULTS

A total of 184 patients were evaluated; at least one respiratory virus was identified in 163 (88.6%) patients. RSV and RV were the two leading viral etiologies, with 25.5% and 17.3%, respectively. RV bronchiolitis has a comparable severity to RSV but is more common in children of an older age with a history of recurrent wheezing and blood eosinophilia. Decreased tumor necrosis factor-alpha (TNF-α) and interferon gamma (INF-γ) levels were correlated with clinical severity. Patients infected with RV exhibited higher levels of Interleukin (IL)-22, IL-23, IL-25, IL-31, and IL-33 (p < 0.05), whereas those with RSV had higher levels of TNF-α, INF-γ, and IL-10 (p < 0.05). Systemic steroid treatment was associated with higher expressions of IL-4, IL-8, IL-13, and MIP-1α levels (p < 0.05). Cluster analysis revealed a high correlation of IL-33 and IL-31(R² = 0.9731, p < 0.0001).

CONCLUSION

Different viral infections elicited the characteristic clinical presentation and immune profiles in bronchiolitis. Our findings also highlight the role of the IL-33/IL-31 axis in the immunopathogenesis of bronchiolitis.

Regulatory T cells (Tregs) in liver fibrosis

The ability of the human liver to both synthesize extracellular matrix(ECM), as well as regulate fibrogenesis, are integral functions to maintaining homoeostasis. Chronic liver injury stimulates fibrogenesis in response to the imbalance between ECM accumulation and fibrosis resolution. Liver disease that induces fibrogenesis is associated with multiple risk factors like hepatitis infection, schistosomiasis, alcohol, certain drugs, toxicants and emerging aetiology like diabetes and obesity. The activation of hepatic stellate cells (HSCs), whose function is to generate and accumulate ECM, is a pivotal event in liver fibrosis. Simultaneously, HSCs selectively promote regulatory T-cells (Tregs) in an interleukin-2-dependent pattern that displays a dual relationship. On the one hand, Tregs can protect HSCs from NK cell attack, while on the other hand, they demonstrate an inhibitory effect on HSCs. This paper reviews the dual role of Tregs in liver fibrogenesis which includes its promotion of immunosuppression, as well as its activation of fibrosis. In particular, the balance between Tregs and the Th17 cell population, which produce interleukin (IL)-17 and IL-22, is explored to demonstrate their key role in maintaining homoeostasis and immunoregulation. The contradictory roles of Tregs in liver fibrosis in different immune microenvironments and molecular pathways need to be better understood if they are to be deployed to manage this disease.

Severely ill and high-risk COVID-19 patients exhibit increased peripheral circulation of CD62L+ and perforin+ T cells

Introduction

The emergence of SARS-CoV-2, which causes COVID-19, has led to over 400 million reported cases worldwide. COVID-19 disease ranges from asymptomatic infection to severe disease and may be impacted by individual immune differences.

Methods

We used multiparameter flow cytometry to compare CD4+ and CD8+ T cell responses in severe (ICU admitted) and non-severe (admitted to observational unit) hospitalized COVID-19 patients.

Results

We found that patients with severe COVID- 19 had greater frequencies of CD4+ T cells expressing CD62L compared to non-severe patients and greater frequencies of perforin+ CD8+ T cells compared to recovered patients. Furthermore, greater frequencies of CD62L+ CD4+ and CD8+ T cells were seen in severely ill diabetic patients compared to non-severe and non-diabetic patients, and increased CD62L+ CD4+ T cells were also seen in severely ill patients with hypertension.

Discussion

This is the first report to show that CD62L+ T cells and perforin+ T cells are associated with severe COVID-19 illness and are significantly increased in patients with high-risk pre-existing conditions including older age and diabetes. These data provide a potential biological marker for severe COVID-19.

The immunomodulation role of Th17 and Treg in renal transplantation

Kidney transplantation (KT) is an ultimate treatment of end-stage chronic kidney disease, which can meet a lot of complications induced by immune system. With under-controlled immunosuppression, the patient will obtain a good prognosis. Otherwise, allograft disfunction will cause severe organ failure and even immune collapse. Acute or chronic allograft dysfunction after KT is related to Th17, Treg, and Th17/Treg to a certain extent. Elevated Th17 levels may lead to acute rejection or chronic allograft dysfunction. Treg mainly plays a protective role on allografts by regulating immune response. The imbalance of the two may further aggravate the balance of immune response and damage the allograft. Controlling Th17 level, improving Treg function and level, and adjusting Th17/Treg ratio may have positive effects on longer allograft survival and better prognosis of receptors.

Decoding the role of immune T cells: A new territory for improvement of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a new emerging concept and is associated with metabolic dysfunction, generally replacing the name of nonalcoholic fatty liver disease (NAFLD) due to heterogeneous liver condition and inaccuracies in definition. The prevalence of MAFLD is rising by year due to dietary changes, metabolic disorders, and no approved therapy, affecting a quarter of the global population and representing a major economic problem that burdens healthcare systems. Currently, in addition to the common causative factors like insulin resistance, oxidative stress, and lipotoxicity, the role of immune cells, especially T cells, played in MAFLD is increasingly being emphasized by global scholars. Based on the diverse classification and pathophysiological effects of immune T cells, we comprehensively analyzed their bidirectional regulatory effects on the hepatic inflammatory microenvironment and MAFLD progression. This interaction between MAFLD and T cells was also associated with hepatic-intestinal immune crosstalk and gut microbiota homeostasis. Moreover, we pointed out several T-cell-based therapeutic approaches including but not limited to adoptive transfer of T cells, fecal microbiota transplantation, and drug therapy, especially for natural products and Chinese herbal prescriptions. Overall, this study contributes to a better understanding of the important role of T cells played in MAFLD progression and corresponding therapeutic options and provides a potential reference for further drug development.

Bioinformatics and systems biology approaches to identify the effects of COVID-19 on neurodegenerative diseases: A review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease (COVID-19), has been devastated by COVID-19 in an increasing number of countries and health care systems around the world since its announcement of a global pandemic on 11 March 2020. During the pandemic, emerging novel viral mutant variants have caused multiple outbreaks of COVID-19 around the world and are prone to genetic evolution, causing serious damage to human health. As confirmed cases of COVID-19 spread rapidly, there is evidence that SARS-CoV-2 infection involves the central nervous system (CNS) and peripheral nervous system (PNS), directly or indirectly damaging neurons and further leading to neurodegenerative diseases (ND), but the molecular mechanisms of ND and CVOID-19 are unknown. We employed transcriptomic profiling to detect several major diseases of ND: Alzheimer 's disease (AD), Parkinson' s disease (PD), and multiple sclerosis (MS) common pathways and molecular biomarkers in association with COVID-19, helping to understand the link between ND and COVID-19. There were 14, 30 and 19 differentially expressed genes (DEGs) between COVID-19 and Alzheimer 's disease (AD), Parkinson' s disease (PD) and multiple sclerosis (MS), respectively; enrichment analysis showed that MAPK, IL-17, PI3K-Akt and other signaling pathways were significantly expressed; the hub genes (HGs) of DEGs between ND and COVID-19 were CRH, SST, TAC1, SLC32A1, GAD2, GAD1, VIP and SYP. Analysis of transcriptome data suggests multiple co-morbid mechanisms between COVID-19 and AD, PD, and MS, providing new ideas and therapeutic strategies for clinical prevention and treatment of COVID-19 and ND.

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.

Integrated relationship of nasopharyngeal airway host response and microbiome associates with bronchiolitis severity

Bronchiolitis is a leading cause of infant hospitalizations but its immunopathology remains poorly understood. Here we present data from 244 infants hospitalized with bronchiolitis in a multicenter prospective study, assessing the host response (transcriptome), microbial composition, and microbial function (metatranscriptome) in the nasopharyngeal airway, and associate them with disease severity. We investigate individual associations with disease severity identify host response, microbial taxonomical, and microbial functional modules by network analyses. We also determine the integrated relationship of these modules with severity. Several modules are significantly associated with risks of positive pressure ventilation use, including the host-type I interferon, neutrophil/interleukin-1, T cell regulation, microbial-branched-chain amino acid metabolism, and nicotinamide adenine dinucleotide hydrogen modules. Taken together, we show complex interplays between host and microbiome, and their contribution to disease severity.

CD4+ T cell activation and inflammation in NASH-related fibrosis

Liver fibrosis is a common pathological feature of end stage liver failure, a severe life-threatening disease worldwide. Nonalcoholic fatty liver disease (NAFLD), especially its more severe form with steatohepatitis (NASH), results from obesity, type 2 diabetes and metabolic syndrome and becomes a leading cause of liver fibrosis. Genetic factor, lipid overload/toxicity, oxidative stress and inflammation have all been implicated in the development and progression of NASH. Both innate immune response and adaptive immunity contribute to NASH-associated inflammation. Innate immunity may cause inflammation and subsequently fibrosis via danger-associated molecular patterns. Increasing evidence indicates that T cell-mediated adaptive immunity also provokes inflammation and fibrosis in NASH via cytotoxicity, cytokines and other proinflammatory and profibrotic mediators. Recently, the single-cell transcriptome profiling has revealed that the populations of CD4+ T cells, CD8+ T cells, γδ T cells, and TEMs are expanded in the liver with NASH. The activation of T cells requires antigen presentation from professional antigen-presenting cells (APCs), including macrophages, dendritic cells, and B-cells. However, since hepatocytes express MHCII molecules and costimulators, they may also act as an atypical APC to promote T cell activation. Additionally, the phenotypic switch of hepatocytes to proinflammatory cells in NASH contributes to the development of inflammation. In this review, we focus on T cells and in particular CD4+ T cells and discuss the role of different subsets of CD4+ T cells including Th1, Th2, Th17, Th22, and Treg in NASH-related liver inflammation and fibrosis.

The Pathogenic Aspects of Human Parvovirus B19 NS1 Protein in Chronic and Inflammatory Diseases

Background

The nonstructural protein (NS1) of human parvovirus B19 (hPVB19) is considered to be a double-edged sword in its pathogenesis. NS1 protein promotes cell death by apoptosis in erythroid-lineage cells and is also implicated in triggering and the progression of various inflammation and autoimmune disorders.

Objectives

We investigated the possible role of hPVB19 NS1 in the modulation of proinflammatory cytokines in nonpermissive HEK-293T cells.

Methods

A plasmid containing the fully sequenced NS1 gene (pCMV6-AC-GFP-NS1) was transfected into HEK-293T cells. Transfection efficiency was assessed by fluorescent microscopy over time. Mock (pCMV6-AC-GFP) transfected cells were used as controls. The percentage of apoptotic cells was measured by flow cytometry at 24, 48, and 72 h posttransfection. Interleukin 6 (IL-6) mRNA, as a pleiotropic cytokine, was measured by real-time PCR. Furthermore, cellular supernatants were collected to determine the type and quantity of cytokines produced by mock- and NS1-transfected cells using flow cytometry.

Results

Fold change in the expression level of IL-6 mRNA in transfected cells after 72 hr of incubation was found to be 3.01 when compared with mock-transfected cells; however, cell apoptosis did not happen over time. Also, the concentration of cytokines such as IL-2, IL-6, IL-9, IL-17A, IL-21, IL-22, interferon (IFN)-γ, and tumor necrosis factor α (TNF-α) increased in NS1-transfected cells.

Conclusions

Overall, our results indicated that proinflammatory cytokine levels had increased following the expression of hPVB19 NS1 in HEK-293T cells, consistent with a role for NS1 expression facilitating the upregulation of inflammatory reactions. Therefore, hPVB19 NS1 function may play a role in the progression of some chronic and inflammatory diseases.

COVID-19 immunotherapy: Treatment based on the immune cell-mediated approaches

Multiple efforts are currently underway to control and treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19) worldwide. Despite all efforts, the virus that emerged in Wuhan city has rapidly spread globally and led to a public health emergency of international concern (PHEIC) due to the lack of approved antiviral therapy. Nevertheless, SARS-CoV-2 has had a significant influence on the evolution of cellular therapeutic approaches. Adoptive immune cell therapy is innovative and offers either promising prophylactic or therapy for patients with moderate-to-severe COVID-19. This approach is aimed at developing safety and providing secure and effective therapy in combination with standard therapy for all COVID-19 infected individuals. Based on the effective results of previous studies on both inflammatory and autoimmune diseases, various immune cell therapies against COVID-19 have been reviewed and discussed. It must be considered that the application of cell therapy for treatment and to eliminate infected respiratory cells could result in excessive inflammation, so this treatment must be used in combination with other treatments, despite its many beneficial efforts.

COVID-19 and the role of cytokines in this disease

Studies have shown that SARS-CoV-2 has the ability to activate and mature proinflammatory cytokines in the body. Cytokine markers are a group of polypeptide signalling molecules that can induce and regulate many cellular biological processes by stimulating cell receptors at the surface. SARS-CoV-2 has been shown to be associated with activation of innate immunity, and an increase in neutrophils, mononuclear phagocytes, and natural killer cells has been observed, as well as a decrease in T cells including CD4+ and CD8. It is noteworthy that during the SARS-CoV-2 infection, an increase in the secretion or production of IL-6 and IL-8 is seen in COVID-19 patients along with a decrease in CD4+ and CD8+ and T cells in general. SARS-CoV-2 has been shown to significantly increase Th2, Th1/Th17 cells and antibody production in the body of patients with COVID-19. Specific immune profiles of SARS-CoV-2 infection can lead to secondary infections and dysfunction of various organs in the body. It has been shown that Interleukins (such as IL-1, IL-4, IL-6, IL-7, IL-10, IL-12, IL-17, and IL-18), IFN-γ, TNF-α,TGF-β and NF-κB play major roles in the body's inflammatory response to SARS-CoV-2 infection. The most important goal of this review is to study the role of inflammatory cytokines in COVID-19.

Upper respiratory tract bacterial-immune interactions during respiratory syncytial virus infection in infancy

BACKGROUND

The risk factors determining short- and long-term morbidity following acute respiratory infection (ARI) due to respiratory syncytial virus (RSV) in infancy remain poorly understood.

OBJECTIVES

Our aim was to examine the associations of the upper respiratory tract (URT) microbiome during RSV ARI in infancy with the acute local immune response and short- and long-term clinical outcomes.

METHODS

We characterized the URT microbiome by 16S ribosomal RNA sequencing and assessed the acute local immune response by measuring 53 immune mediators with high-throughput immunoassays in 357 RSV-infected infants. Our short- and long-term clinical outcomes included several markers of disease severity and the number of wheezing episodes in the fourth year of life, respectively.

RESULTS

We found several specific URT bacterial-immune mediator associations. In addition, the Shannon ⍺-diversity index of the URT microbiome was associated with a higher respiratory severity score (β =.50 [95% CI = 0.13-0.86]), greater odds of a lower ARI (odds ratio = 1.63 [95% CI = 1.10-2.43]), and higher number of wheezing episodes in the fourth year of life (β = 0.89 [95% CI = 0.37-1.40]). The Jaccard β-diversity index of the URT microbiome differed by level of care required (P = .04). Furthermore, we found an interaction between the Shannon ⍺-diversity index of the URT microbiome and the first principal component of the acute local immune response on the respiratory severity score (P = .048).

CONCLUSIONS

The URT microbiome during RSV ARI in infancy is associated with the acute local immune response, disease severity, and number of wheezing episodes in the fourth year of life. Our results also suggest complex URT bacterial-immune interactions that can affect the severity of the RSV ARI.

Crucial role of T cells in NAFLD-related disease: A review and prospect

Nonalcoholic fatty liver disease (NAFLD) includes a series of hepatic manifestations, starting with liver steatosis and potentially evolving towards nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis or even hepatocellular carcinoma (HCC). Its incidence is increasing worldwide. Several factors including metabolic dysfunction, oxidative stress, lipotoxicity contribute to the liver inflammation. Several immune cell-mediated inflammatory processes are involved in NAFLD in which T cells play a crucial part in the progression of the disease. In this review, we focus on the role of different subsets of both conventional and unconventional T cells in pathogenesis of NAFLD. Factors regarding inflammation and potential therapeutic approaches targeting immune cells in NASH are also discussed.

Myasthenia gravis: The pharmacological basis of traditional Chinese medicine for its clinical application

We aimed to investigate the target and signal pathway of Smilacis Glabrae Rhixoma (SGR) in the treatment of myasthenia gravis (MG) based on network pharmacology, and to explore its potential molecular mechanism. The main active components of SGR were searched in the pharmacology database of traditional Chinese medicine systems, and analysis platform. The related targets of SGR were obtained by Genecards, connective tissue disease, therapeutic target database, Drugbank, and Online Mendelian Inheritance in Man database. Moreover, the target information was corrected through UniProtKB and also, this data integrated to draw the "Ingredients-targets" network of SGR. Protein interaction analysis was performed in data platform, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways as well as enrichment analysis on disease-drug target was carried out through metascape online platform. A total of 15 active components were collected from SGR, which correspond to 159 targets; There were 1758 MG-related targets; there are 81 targets related to both drug components and diseases, including 12 key targets. In GO bioaccumulation analysis, 1933 GO items were gathered, which were mainly related to the metabolism of active oxygen species and the active factors of postsynaptic neurotransmitter receptor. According to KEGG analysis, SGR may play a role in the treatment of MG through phosphatidylinositol-3-kinase-protein kinase B signaling pathway, T-cell receptor, cAMP, tumor necrosis factor (TNF), and interleukin-17 (IL-17) signaling pathway, Th17 cell differentiation, endocrine resistance, hepatitis, and some cancer pathways. This study shows that SGR mainly treat myasthenia gravis through the regulation of TNF, MAPK1, JUN, TP53 and other targets, T-cell receptor, TNF, and IL-17 signaling pathway, Th17 cell differentiation and other pathways, which reflects the characteristics of multicomponent, multitarget, and multichannel of traditional Chinese medicine, and providing a certain pharmacological basis for the follow-up study.

COVID-19 immunopathology with emphasis on Th17 response and cell-based immunomodulation therapy: Potential targets and challenges

The role of the immune system against coronavirus disease 2019 (COVID-19) is unknown in many aspects, and the protective or pathologic mechanisms of the immune response are poorly understood. Pro-inflammatory cytokine release and a consequent cytokine storm can lead to acute respiratory distress syndrome (ARDS) and result in multi-organ failure. There are many T cell subsets during anti-viral immunity. The Th17-associated response, as a pro-inflammatory pathway, and its consequent outcomes in many autoimmune disorders play a fundamental role in progression of systemic hyper-inflammation during COVID-19. Therapeutic strategies based on immunomodulation therapy could be helpful for targeting hyper-inflammatory immune responses in COVID-19, especially Th17-related inflammation and hyper-cytokinemia. Cell-based immunotherapeutic approaches including mesenchymal stem cells (MSCs), tolerogenic dendritic cells (tolDCs) and regulatory T cells (Tregs) seem to be promising strategies as orchestrators of the immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this review, we highlight Th17-related immunopathology of SARS-CoV-2 infection and discuss cell-based immunomodulatory strategies and their mechanisms for regulation of the hyper-inflammation during COVID-19.

The role of TNFR2+ Tregs in COVID-19: An overview and a potential therapeutic strategy

COVID-19 is a multi-faceted disease ranging from asymptomatic to severely ill condition that primarily affects the lungs and could advance to other organs as well. It's causing factor, SARS-CoV-2 is recognized to develop robust cell-mediated immunity that responsible to either control or exaggerate the infection. As an important cell subset that control immune responses and are significantly dysregulated in COVID-19, Tregs is proposed to be considered for COVID-19 management. Among its hallmark, TNFR2 is recently recognized to play important role in the function and survival of Tregs. This review gathers available TNFR2 agonists to directly target Tregs as a potential approach to overcome immune dysregulation that affect the severity in COVID-19. Furthermore, this review performs a rigid body docking of TNF-TNFR2 interaction and such interaction with TNFR2 agonist to predict the optimal targeting approach.

Interleukin-17-A multifaceted cytokine in viral infections

Viral infections are a major threat to the human population due to the lack of selective therapeutic measures. The morbidity and mortality reported worldwide are very alarming against viral pathogens. The proinflammatory environment is required for viral inhibition by initiating the host immune response. The host immune response fights these pathogens by secreting different cytokines. Interleukin-17 (IL-17) a proinflammatory cytokine mainly produced by T helper type 17 cells, plays a vital role in the regulation of host immune response against various pathogens, including viruses. However, dysregulated production of IL-17 induces chronic inflammation, autoimmune disorders, and may lead to cancer. Recent studies suggest that IL-17 is not only involved in the antiviral immune response but also promotes virus-mediated illnesses. In this review, we discuss the protective and pathogenic role of IL-17 against various viral infections. A detailed understanding of IL-17 during viral infections could contribute to improve therapeutic measures and enable the development of an efficient and safe IL-17 based immunotherapy.

Crosstalk of Microorganisms and Immune Responses in Autoimmune Neuroinflammation: A Focus on Regulatory T Cells

Regulatory T cells (Tregs) are the major determinant of peripheral immune tolerance. Many Treg subsets have been described, however thymus-derived and peripherally induced Tregs remain the most important subpopulations. In multiple sclerosis, a prototypical autoimmune disorder of the central nervous system, Treg dysfunction is a pathogenic hallmark. In contrast, induction of Treg proliferation and enhancement of their function are central immune evasion mechanisms of infectious pathogens. In accordance, Treg expansion is compartmentalized to tissues with high viral replication and prolonged in chronic infections. In friend retrovirus infection, Treg expansion is mainly based on excessive interleukin-2 production by infected effector T cells. Moreover, pathogens seem also to enhance Treg functions as shown in human immunodeficiency virus infection, where Tregs express higher levels of effector molecules such as cytotoxic T-lymphocyte-associated protein 4, CD39 and cAMP and show increased suppressive capacity. Thus, insights into the molecular mechanisms by which intracellular pathogens alter Treg functions might aid to find new therapeutic approaches to target central nervous system autoimmunity. In this review, we summarize the current knowledge of the role of pathogens for Treg function in the context of autoimmune neuroinflammation. We discuss the mechanistic implications for future therapies and provide an outlook for new research directions.

A Systematic Review and Meta-analysis of Animal Studies Investigating the Relationship Between Serum Antibody, T Lymphocytes, and Respiratory Syncytial Virus Disease

BACKGROUND

Respiratory syncytial virus (RSV) infections occur in human populations around the globe, causing disease of variable severity, disproportionately affecting infants and older adults (>65 years of age). Immune responses can be protective but also contribute to disease. Experimental studies in animals enable detailed investigation of immune responses, provide insights into clinical questions, and accelerate the development of passive and active vaccination. We aimed to review the role of antibody and T-cell responses in relation to RSV disease severity in animals.

METHODS

Systematic review and meta-analysis of animal studies examining the association between T-cell responses/phenotype or antibody titers and severity of RSV disease. The PubMed, Zoological Record, and Embase databases were screened from January 1980 to May 2018 to identify animal studies of RSV infection that assessed serum antibody titer or T lymphocytes with disease severity as an outcome. Sixty-three studies were included in the final review.

RESULTS

RSV-specific antibody appears to protect from disease in mice, but such an effect was less evident in bovine RSV. Strong T-cell, Th1, Th2, Th17, CD4/CD8 responses, and weak Treg responses accompany severe disease in mice.

CONCLUSIONS

Murine studies suggest that measures of T-lymphocyte activity (particularly CD4 and CD8 T cells) may be predictive biomarkers of severity. Further inquiry is merited to validate these results and assess relevance as biomarkers for human disease.

Molecular Mechanism of Jinchan Oral Liquid in the Treatment of Children with Respiratory Syncytial Virus Pneumonia Based on Network Pharmacology and Molecular Docking Technology

Objective

Exploration of the underlying molecular mechanism of Jinchan Oral Liquid (JOL) in treating children with the respiratory syncytial virus (RSV) pneumonia to provide new evidence for the clinical application.

Methods

The active components and target genes of JOL were screened by the TCMSP database. The targets of RSV pneumonia were obtained from the GeneCards, OMIM, DrugBank, and PharmGKB database. Then, we constructed the active component-target network and screened the core genes. The overlaps were screened for PPI network analysis, GO analysis, and KEGG analysis. Finally, result validation was performed by molecular docking.

Results

According to the screening criteria of the ADME, 74 active compounds of JOL were obtained; after removing redundant targets, we selected 180 potential targets. By screening the online database, 893 RSV pneumonia-related targets were obtained. A total of 82 overlapping genes were chosen by looking for the intersection. The STRING online database was used to acquire PPI relationships, and 16 core genes were obtained. GO and KEGG analyses showed that the main pathways of JOL in treating RSV pneumonia include TNF signaling pathway and IL17 signaling pathway. The molecular docking results showed that the active compounds of JOL had a good affinity with the core genes.

Conclusion

In this study, we preliminarily discussed the main active ingredients, related targets, and pathways of JOL and predicted the pharmacodynamic basis and the potential therapeutic mechanisms of RSV pneumonia. In summary, the network pharmacology strategy may be helpful for the discovery of multitarget drugs against complex diseases.

Novel Insights into the Role of Probiotics in Respiratory Infections, Allergies, Cancer, and Neurological Abnormalities

In recent years, probiotics have attracted public attention and transformed the social perception of microorganisms, convening a beneficial role/state on human health. With aging, the immune system, body physiology, and intestinal microbiota tend to change unfavorably, resulting in many chronic conditions. The immune-mediated disorders can be linked to intestinal dysbiosis, consequently leading to immune dysfunctions and a cluster of conditions such as asthma, autoimmune diseases, eczema, and various allergies. Probiotic bacteria such as Lactobacillus and Bifidobacterium species are considered probiotic species that have a great immunomodulatory and anti-allergic effect. Moreover, recent scientific and clinical data illustrate that probiotics can regulate the immune system, exert anti-viral and anti-tumoral activity, and shields the host against oxidative stress. Additionally, microbiota programming by probiotic bacteria can reduce and prevent the symptoms of respiratory infections and ameliorate the neurological status in humans. This review describes the most recent clinical findings, including safe probiotic therapies aiming to medicate respiratory infections, allergies, cancer, and neurological disorders due to their physiological interconnection. Subsequently, we will describe the major biological mechanism by which probiotic bacteriotherapy expresses its anti-viral, anti-allergic, anticancer, and neuro-stimulatory effects.

The Alterations in and the Role of the Th17/Treg Balance in Metabolic Diseases

Chronic inflammation plays an important role in the development of metabolic diseases. These include obesity, type 2 diabetes mellitus, and metabolic dysfunction-associated fatty liver disease. The proinflammatory environment maintained by the innate immunity, including macrophages and related cytokines, can be influenced by adaptive immunity. The function of T helper 17 (Th17) and regulatory T (Treg) cells in this process has attracted attention. The Th17/Treg balance is regulated by inflammatory cytokines and various metabolic factors, including those associated with cellular energy metabolism. The possible underlying mechanisms include metabolism-related signaling pathways and epigenetic regulation. Several studies conducted on human and animal models have shown marked differences in and the important roles of Th17/Treg in chronic inflammation associated with obesity and metabolic diseases. Moreover, Th17/Treg seems to be a bridge linking the gut microbiota to host metabolic disorders. In this review, we have provided an overview of the alterations in and the functions of the Th17/Treg balance in metabolic diseases and its role in regulating immune response-related glucose and lipid metabolism.

Hyperglycemia results in decreased immune cell infiltration and increased viral load in the lung in a mouse model of RSV infection

Respiratory Syncytial virus (RSV) infection is a feared disease in vulnerable populations with impaired immune responses. There is currently no vaccine against RSV and young children along with elderly people are at increased risk of severe or sometimes life-threatening RSV infection. Hyperglycemia with immunomodulatory patterns can impact on infectious disease outcomes and immune system responses in diabetic patients. Even though research continues to uncover the complex mechanisms underlying RSV immunopathogenesis and diabetes mellitus disease separately, limited information is available about interaction between these two phenomena. Here, we evaluated the influence of hyperglycemia as the hallmark of diabetes mellitus disease on the pathogenesis and immunopathogenesis of RSV in a mouse model. In this experiment, hyperglycemia was induced by intraperitoneal injection of Streptozotocin (STZ), and after diabetes confirmation, mice were infected with RSV-A2, and the immune responses were followed for 5 days until the mice were sacrificed. Analyses on airway immune cell influx, T-Lymphocyte subtypes, cytokines secretion, lung histopathology, and viral load were conducted. Our results showed that hyperglycemia resulted in reduced lung immune cells infiltration totally and it was associated with decreased pathological damage of the lung. Following RSV infection in hyperglycemic mice, the ratio of CD4/CD8 T-Lymphocytes due to CD8+ depletion, increased. Furthermore, the level of IFN-γ and IL-17A cytokines decreased, whereas IL-10 showed an upward trend and the viral load increased in hyperglycemic mice compared with normoglycemic mice. In conclusion, these findings indicate that hyperglycemia can ameliorate and downregulate RSV-induced inflammatory and antiviral responses, and result in increment of viral load.

ER stress protein PERK promotes inappropriate innate immune responses and pathogenesis during RSV infection

The activation of dendritic cells (DC) during respiratory viral infections is central to directing the immune response and the pathologic outcome. In these studies, the effect of RSV infection on development of ER stress responses and the impact on innate immunity was examined. The upregulation of ER stress was closely associated with the PERK pathway through the upregulation of CHOP in RSV infected DC. The inhibition of PERK corresponded with decreased EIF2a phosphorylation but had no significant effect on Nrf2 in DC, two primary pathways regulated by PERK. Subsequent studies identified that by blocking PERK activity in infected DC an altered ER stress response and innate cytokine profile was observed with the upregulation of IFNβ and IL-12, coincident to the down regulation of IL-1β. When mitochondria respiration was assessed in PERK deficient DC there were increased dysfunctional mitochondria after RSV infection that resulted in reduced oxygen consumption rates (OCR) and ATP production indicating altered cellular metabolism. Use of a CD11c targeted genetic deleted murine model, RSV infection was characterized by reduced inflammation and diminished mucus staining as well as reduced mucus-associated gene gob5 expression. The assessment of the cytokine responses showed decreased IL-13 and IL-17 along with diminished IL-1β in the lungs of PERK deficient infected mice. When PERK-deficient animals were assessed in parallel for lung leukocyte numbers, animals displayed significantly reduced myeloid and activated CD4 and CD8 T cell numbers. Thus, the PERK activation pathway may provide a rational target for altering the severe outcome of an RSV infection through modifying immune responses.

Propolis antiviral and immunomodulatory activity: a review and perspectives for COVID-19 treatment

OBJECTIVES

Viral outbreaks are a frequent concern for humans. A great variety of drugs has been used to treat viral diseases, which are not always safe and effective and may induce adverse effects, indicating the need for new antiviral drugs extracted from natural sources. Propolis is a bee-made product exhibiting many biological properties. An overview of viruses, antiviral immunity, propolis safety and its immunomodulatory and antiviral action is reported, as well as perspectives for coronavirus disease 2019 (COVID-19) treatment. PubMed platform was used for data collection, searching for the keywords "propolis", "virus", "antiviral", "antimicrobial" and "coronavirus".

KEY FINDINGS

Propolis is safe and exerts antiviral and immunomodulatory activity; however, clinical trials should investigate its effects on individuals with viral diseases, in combination or not with antiviral drugs or vaccines.

SUMMARY

Regarding COVID-19, the effects of propolis should be investigated directly on the virus in vitro or on infected individuals alone or in combination with antiviral drugs, due to its immunomodulatory and anti-inflammatory action. Propolis administration simultaneously with vaccines should be analyzed, due to its adjuvant properties, to enhance the individuals' immune response. The search for therapeutic targets may be useful to find out how propolis can help to control COVID-19.

Long non-coding RNA GAS5 regulates Th17/Treg imbalance in childhood pneumonia by targeting miR-217/STAT5

The imbalance of helper T (Th) 17 and regulatory T (Treg) cells plays an important role in the pathogenesis of pneumonia. This study aims to investigate the role and mechanism of long non-coding RNA growth arrest-specific 5 (GAS5) in the differentiation of Th17 cells and Tregs in childhood pneumonia. Expression of GAS5, miR-217, signal transducer and activator of transcription-5 (STAT5), receptor-related orphan receptor γt (RORγt), and transcription factor Forkhead box P3 (Foxp3) were examined by qRT-PCR and western blot. The percentage of Th17 cells and Tregs in CD4⁺ T cells were measured by flow cytometry. The interaction between miR-217 and GAS5 or STAT5 was analyzed by luciferase reporter assay. Downregulated GAS5 expression and Treg cell percentage, and upregulated Th17 cell percentage were observed in pneumonia patients when compared with the healthy controls. Furthermore, GAS5 overexpression corrected the imbalanced Th17/Treg in peripheral blood CD4⁺ T cells derived from pneumonia patients, and this effect was reversed by miR-217 mimic and STAT5 silencing. Mechanistically, GAS5 acted as a sponge of miR-217 to reduce binding of miR-217 to its target STAT5, leading to upregulation of STAT5 expression. Taken together, GAS5 corrects the Treg/Th17 imbalance by targeting the miR-217/STAT5 axis in childhood pneumonia.

T Helper 17 Response to Severe Acute Respiratory Syndrome Coronavirus 2: A Type of Immune Response with Possible Therapeutic Implications

The initial immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) includes an interferon-dependent antiviral response. A late and uncontrolled inflammatory response characterized by high activity of proinflammatory cytokines and the recruitment of neutrophils and macrophages develops in predisposed individuals and is potentially harmful in some cases. Interleukin (IL)-17 is one of the many cytokines released during coronavirus disease 2019 (COVID-19). IL-17 is crucial in recruiting and activating neutrophils, cells that can migrate to the lung, and are heavily involved in the pathogenesis of COVID-19. During the infection T helper 17 (Th17) cells and IL-17-related pathways are associated with a worse outcome of the disease. All these have practical consequences considering that some drugs with therapeutic targets related to the Th17 response may have a beneficial effect on patients with SARS-CoV-2 infection. Herein, we present the arguments underlying our assumption that blocking the IL-23/IL-17 axis using targeted biological therapies as well as drugs that act indirectly on this pathway such as convalescent plasma therapy and colchicine may be good therapeutic options.

A multifunctional nanoparticle as a prophylactic and therapeutic approach targeting respiratory syncytial virus

Respiratory Syncytial Virus (RSV) has been a major health concern globally for decades, yet no effective prophylactic or treatment regimen is available. The key viral proteins responsible for RSV pathology include the fusion protein (F), the immunomodulatory non-structural-protein 1 (NS1) and the phosphoprotein (P) involved in viral replication. Herein, we developed a novel shell-core multifunctional nanosystem with dual payload: a plasmid construct encoding for shRNAs against NS1 and P, and an anti-fusion peptide (HR2D). Anti-ICAM1 antibody conjugated on the nanoparticle (NP) surface is used to target RSV infected cells. Our data show the potential of this nanosystem as a prophylactic and/or a therapeutic regimen against RSV infection. Furthermore, therapy of RSV infected mice with this nanosystem, in addition to reducing viral load, modulated expression of Th2 and allergy-associated cytokines such as IL4, IL-13 and IL-17 indicating a direct role of this nanosystem in the mechanisms involved in the immunoregulation of disease pathogenesis.

Addition of probiotics to antibiotics improves the clinical course of pneumonia in young people without comorbidities: a randomized controlled trial

This study was aimed at investigating the clinical efficacy of probiotics in pneumonia patients. To this end, we enrolled 80 participants diagnosed with pneumonia at Naval Pohang Hospital, Pohang, Korea, from May 2016 to January 2017. The participants were randomly assigned to the control and probiotic groups depending on whether they received probiotics. All participants clinically improved but 22.6% of the participants complained of abnormal stool habits after pneumonia treatment. In comparison, fever duration was significantly shorter in the probiotic group, and the group exhibited an improved general condition. The probiotic group also showed better stool characteristics according to the Bristol stool scale (P = 0.009). Notably, the serum hs-CRP levels were significantly lower in the probiotic group at 2 weeks of treatment (P = 0.015), and all participants in the probiotic group achieved their levels within the normal range. Flow cytometry was used to analyze T-helper 17 (Th17) cells and regulatory T cells (Tregs). Tregs were promoted and the Th17 cell/Treg ratio was suppressed after 2 weeks of treatment in the probiotic group (P = 0.007 and 0.037, respectively). This study demonstrated that probiotics improved clinical symptoms and normalized inflammatory biomarker levels in patients with pneumonia. Early infection and inflammation recovery may be due to the immunomodulatory effects of probiotics by facilitating the subset of Tregs and suppressing the Th17 cell/Treg ratio.

The role of Th17 cells in viral infections

The present review provides an overview of recent advances regarding the function of Th17 cells and their produced cytokines in the progression of viral diseases. Viral infections alone do not lead to virus-induced malignancies, as both genetic and host safety factors are also involved in the occurrence of malignancies. Acquired immune responses, through the differentiation of Th17 cells, form the novel components of the Th17 cell pathway when reacting with viral infections all the way from the beginning to its final stages. As a result, instead of inducing the right immune responses, these events lead to the suppression of the immune system. In fact, the responses from Th17 cells during persistent viral infections causes chronic inflammation through the production of IL-17 and other cytokines which provide a favorable environment for tumor growth and its development. Additionally, during the past decade, these cells have been understood to be involved in tumor progression and metastasis. However, further research is required to understand Th17 cells' immune mechanisms in the vast variety of viral diseases. This review aims to determine the roles and effects of the immune system, especially Th17 cells, in the progression of viral diseases; which can be highly beneficial for the diagnosis and treatment of these infections.

Genetic influences on viral-induced cytokine responses in the lung

Infection with respiratory viruses such as influenza, respiratory syncytial virus and coronavirus provides a difficult immunological challenge for the host, where a balance must be established between controlling viral replication and limiting damage to the delicate lung structure. Although the genetic architecture of host responses to respiratory viral infections is not yet understood, it is clear there is underlying heritability that influences pathogenesis. Immune control of virus replication is essential in respiratory infections, but overt activation can enhance inflammation and disease severity. Cytokines initiate antiviral immune responses but are implicated in viral pathogenesis. Here, we discuss how host genetic variation may influence cytokine responses to respiratory viral infections and, based on our current understanding of the role that cytokines play in viral pathogenesis, how this may influence disease severity. We also discuss how induced pluripotent stem cells may be utilised to probe the mechanistic implications of allelic variation in genes in virus-induced inflammatory responses. Ultimately, this could help to design better immune modulators, stratify high risk patients and tailor anti-inflammatory treatments, potentially expanding the ability to treat respiratory virus outbreaks in the future.

Regulatory T cells: A potential weapon to combat COVID-19?

Since the end of December 2019, a novel coronavirus SARS-CoV-2 began to spread, an infection disease termed COVID-19. The virus has spread throughout the world in a short period of time, resulting in a pandemic. The number of reported cases in global reached 5 695 596 including 352 460 deaths, as of May 27, 2020. Due to the lack of effective treatment options for COVID-19, various strategies are being tested. Recently, pathologic studies conducted by two teams in China revealed immunopathologic abnormalities in lung tissue. These results have implications for immunotherapy that could offer a novel therapy strategy for combating lethal viral pneumonia. This review discusses the clinical and pathological features of COVID-19, the roles of immune cells in pathological processes, and the possible avenues for induction of immunosuppressive T regulatory cells attenuating lung inflammation due to viral infection. It is our hope that these proposals may both be helpful in understanding the novel features of SARS-CoV-2 pneumonia as well as providing new immunological strategies for treating the severe sequelae of disease manifestations seen in people infected with SARS-CoV-2.

A Case for Targeting Th17 Cells and IL-17A in SARS-CoV-2 Infections

SARS-CoV-2, the virus causing COVID-19, has infected millions and has caused hundreds of thousands of fatalities. Risk factors for critical illness from SARS-CoV-2 infection include male gender, obesity, diabetes, and age >65. The mechanisms underlying the susceptibility to critical illness are poorly understood. Of interest, these comorbidities have previously been associated with increased signaling of Th17 cells. Th17 cells secrete IL-17A and are important for clearing extracellular pathogens, but inappropriate signaling has been linked to acute respiratory distress syndrome. Currently there are few treatment options for SARS-CoV-2 infections. This review describes evidence linking risk factors for critical illness in COVID-19 with increased Th17 cell activation and IL-17 signaling that may lead to increased likelihood for lung injury and respiratory failure. These findings provide a basis for testing the potential use of therapies directed at modulation of Th17 cells and IL-17A signaling in the treatment of COVID-19.

Increased Adiposity Associated With Increased Length of Stay for Infants With Bronchiolitis

OBJECTIVES

Excess adiposity upregulates proinflammatory adipokines in infancy that have also been implicated in the pathogenesis of bronchiolitis. The association between excess adiposity and severity of disease in bronchiolitis is unclear. We sought to examine the association between adiposity and length of hospitalization and risk of PICU transfer in children with bronchiolitis.

METHODS

We conducted a retrospective cohort study examining infants 24 months and younger hospitalized at an academic children's hospital with bronchiolitis, grouped by weight status (BMI z score and ponderal index). Data were extracted from the medical record, including the following relevant covariates: age, sex, race and/or ethnicity, and International Classification of Diseases, 10th Revision codes. Outcomes included length of stay (LOS) and PICU transfer. We used multiple regression to examine the association between each anthropometric measure and LOS and likelihood of PICU transfer.

RESULTS

There were 765 children in the final sample, 599 without a significant comorbidity (eg, prematurity, congenital heart disease). The median LOS was 2.8 days (interquartile range 1.7-4.9 days). LOS increased with increasing ponderal index quartile (P = .001). After accounting for age and significant comorbidities, we used multivariable regression to identify a significant association between increasing ponderal index and LOS (P = .04) and no association between BMI and LOS. Logistic regression did not reveal an association between either anthropometric measure and PICU transfer.

CONCLUSIONS

In this study, we identified an association between a measure of excess adiposity in infants and length of hospitalization for bronchiolitis. Further work is needed to confirm this association, examine potential mechanisms, and account for other potential confounders.

Network pharmacology to dissect the mechanisms of Yinlai Decoction for pneumonia

BACKGROUND

Pneumonia is a common respiratory disorder, which brings an enormous financial burden to the medical system. However, the current treatment options for pneumonia are limited because of drug resistance and side effects. Our previous study preliminarily confirmed that Yinlai Decoction (YD), a common prescription for pneumonia in clinical practice, can regulate the expression of inflammatory factors, but the mechanisms are unknown yet.

METHODS

In our work, a method named network pharmacology was applied, which investigated the underlying mechanisms of herbs based on a variety of databases. We obtained bioactive ingredients of YD on TCMSP database and collected potential targets of these ingredients by target fishing. Then the pneumonia-related targets database was built by TTD, Drugbank, HPO, OMIM, and CTD. Based on the matching targets between YD and pneumonia, the PPI network was built by STRING to analyze the interactions among these targets and then input into Cytoscape for further topological analysis. DAVID and KEGG were utilized for GO and pathway enrichment analysis. Then rat model based on LPS stimulated pneumonia was used to verify the possible mechanism of YD in treating pneumonia.

RESULTS

Sixty-eight active ingredients, 103 potential targets and 8 related pathways, which likely exert a number of effects, were identified. Three networks were constructed using Cytoscape, which were herb-component-network, YD-pneumonia target network, and herb-component-YD target-pneumonia network. YD was verified to treat LPS-induced pneumonia by regulating the inflammatory factor IL-6, which was a predicted target.

CONCLUSION

Network analysis indicated that YD could alleviate the symptoms and signs of pneumonia through regulating host immune inflammatory response, angiogenesis and vascular permeability, the barrier function of the airway epithelial cells, hormone releasing and cell growth, proliferation, and apoptosis.

RSV Reprograms the CDK9•BRD4 Chromatin Remodeling Complex to Couple Innate Inflammation to Airway Remodeling

Respiratory syncytial virus infection is responsible for seasonal upper and lower respiratory tract infections worldwide, causing substantial morbidity. Self-inoculation of the virus into the nasopharynx results in epithelial replication and distal spread into the lower respiratory tract. Here, respiratory syncytial virus (RSV) activates sentinel cells important in the host inflammatory response, resulting in epithelial-derived cytokine and interferon (IFN) expression resulting in neutrophilia, whose intensity is associated with disease severity. I will synthesize key findings describing how RSV replication activates intracellular NFκB and IRF signaling cascades controlling the innate immune response (IIR). Recent studies have implicated a central role for Scg1a1⁺ expressing progenitor cells in IIR, a cell type uniquely primed to induce neutrophilic-, T helper 2 (Th2)-polarizing-, and fibrogenic cytokines that play distinct roles in disease pathogenesis. Molecular studies have linked the positive transcriptional elongation factor-b (P-TEFb), a pleiotrophic chromatin remodeling complex in immediate-early IIR gene expression. Through intrinsic kinase activity of cyclin dependent kinase (CDK) 9 and atypical histone acetyl transferase activity of bromodomain containing protein 4 (BRD4), P-TEFb mediates transcriptional elongation of IIR genes. Unbiased proteomic studies show that the CDK9•BRD4 complex is dynamically reconfigured by the innate response and targets TGFβ-dependent fibrogenic gene networks. Chronic activation of CDK9•BRD4 mediates chromatin remodeling fibrogenic gene networks that cause epithelial mesenchymal transition (EMT). Mesenchymal transitioned epithelial cells elaborate TGFβ and IL6 that function in a paracrine manner to expand the population of subepithelial myofibroblasts. These findings may account for the long-term reduction in pulmonary function in children with severe lower respiratory tract infection (LRTI). Modifying chromatin remodeling properties of the CDK9•BRD4 coactivators may provide a mechanism for reducing post-infectious airway remodeling that are a consequence of severe RSV LRTIs.

Novel decoy cellular vaccine strategy utilizing transgenic antigen-expressing cells as immune presenter and adjuvant in vaccine prototype against SARS-CoV-2 virus

A novel approach modifying cells to express viral markers to elicit protective immunity responses (decoy cellular vaccination) in the prevention of COVID-19 disease is currently being explored. Our approach entails utilizing SARS-CoV-2 Spike antigen-expressing, non-replicating cells as carriers and presenters of immunogenic antigens, so called “I-cells”. By using irradiated cells as presenting vehicles of SARS-CoV-2 viral antigens(s) in a cellular context, these presented viral proteins can be recognized by the host immune system, thus, an efficient protective immune response might be elicited. Another advantage of this strategy is that the manufacturing process is scalable and yields uniform cell products allowing for “off-the-shelf” frozen supply availability. To prevent engraftment and proliferation of the cells after administration, the cells will be irradiated post-harvesting abolishing in vivo replication potential.

Specifically, immunoreactive Spike-1 proteins from SARS-CoV-2 are expressed on the surface of irradiated target I-cells. Utilizing this innovative strategy, these viral antigen-displaying decoy cells will be developed as a vaccine to protect against COVID-19 disease.

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A novel decoy cellular vaccination approach being developed to fight against COVID-19 disease.

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Viral antigen-expressing, non-replicating cells used as both a carrier and antigen-presenting vehicle.

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Scalable manufacturing could allow rapid “off-the-shelf” supply availability.

In vitro model for the assessment of human immune responses to subunit RSV vaccines

Respiratory syncytial virus (RSV) is the single most important cause of serious lower respiratory tract disease in infants and young children worldwide and a high priority for vaccine development. Despite over 50 years of research, however, no vaccine is yet available. One block to vaccine development is an incomplete understanding of the aberrant memory response to the formalin-inactivated RSV vaccine (FI-RSV) given to children in the 1960s. This vaccine caused enhanced respiratory disease (ERD) with later natural RSV infection. Concern that any non-live virus vaccine may also cause ERD has blocked development of subunit vaccines for young children. A number of animal FI-RSV studies suggest various immune mechanisms behind ERD. However, other than limited data from the original FI-RSV trial, there is no information on the human ERD-associated responses. An in vitro model with human blood specimens may shed light on the immune memory responses likely responsible for ERD. Memory T cell responses to an antigen are guided by the innate responses, particularly dendritic cells that present an antigen in conjunction with co-stimulatory molecules and cytokine signaling. Our in vitro model involves human monocyte derived dendritic cells (moDC) and allogenic T cell cultures to assess innate responses that direct T cell responses. Using this model, we evaluated human responses to live RSV, FI-RSV, and subunit RSV G vaccines (G-containing virus-like particles, G-VLP). Similar to findings in animal studies, FI-RSV induced prominent Th2/Th17-biased responses with deficient type-1 responses compared to live virus. Responses to G-VLPs were similar to live virus, i.e. biased towards a Th1 and not a Th2/Th17. Also mutating CX3C motif in G gave a more pronounced moDC responses associated with type-1 T cell responses. This in vitro model identifies human immune responses likely associated with ERD and provides another pre-clinical tool to assess the safety of RSV vaccines.

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.