Bronchiolitis and recurrent wheezing are distinguished by type 2 innate lymphoid cells and immune response

Disease Severity and Cytokine Expression in the Rhinovirus-Induced First Wheezing Episode

Wheezing children infected with rhinovirus (RV) have a markedly increased risk of subsequently developing recurrencies and asthma. No previous studies have assessed the association between cytokine response and the severity of acute illness in the first wheezing episode in children infected with RV. Forty-seven children treated both as inpatients and as outpatients infected with RV only, aged 3-23 months, with severe first wheezing episodes were recruited. During acute illness, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with anti-CD3/anti-CD28 in vitro. A multiplex ELISA was used to quantitatively identify 56 different cytokines. The mean age of the children was 17 months, 74% were males, 79% were hospitalized, and 33% were sensitized. In adjusted analyses, the inpatient group was characterized by decreased expressions of interferon gamma (IFN-γ), interleukin 10 (IL-10), macrophage inflammatory protein 1 alpha (MIP-1α), RANTES (CCL5), and tumor necrosis factor-alpha (TNF-α) and an increased expression of ENA-78 (CXCL5) compared to the outpatient group. The cytokine response profiles from the PBMCs were different between the inpatient and outpatient groups. Our results support that firmly controlled interplay between pro-inflammatory and anti-inflammatory responses are required during acute viral infection to absolve the initial infection leading, to less severe illness.

RIPK1 and RIPK3 inhibitors: potential weapons against inflammation to treat diabetic complications

Diabetes mellitus is a metabolic disease that is characterized by chronic hyperglycemia due to a variety of etiological factors. Long-term metabolic stress induces harmful inflammation leading to chronic complications, mainly diabetic ophthalmopathy, diabetic cardiovascular complications and diabetic nephropathy. With diabetes complications being one of the leading causes of disability and death, the use of anti-inflammatories in combination therapy for diabetes is increasing. There has been increasing interest in targeting significant regulators of the inflammatory pathway, notably receptor-interacting serine/threonine-kinase-1 (RIPK1) and receptor-interacting serine/threonine-kinase-3 (RIPK3), as drug targets for managing inflammation in treating diabetes complications. In this review, we aim to provide an up-to-date summary of current research on the mechanism of action and drug development of RIPK1 and RIPK3, which are pivotal in chronic inflammation and immunity, in relation to diabetic complications which may be benefit for explicating the potential of selective RIPK1 and RIPK3 inhibitors as anti-inflammatory therapeutic agents for diabetic complications.

Torque Teno Virus in Nasopharyngeal Aspirate of Children With Viral Respiratory Infections

BACKGROUND

Torque teno virus (TTV) is a ubiquitous anellovirus responsible for persistent infections and is considered a marker of immune function. The role of TTV as a facilitator of respiratory infections (RIs) is unknown.

OBJECTIVES

Our aim was to estimate, in a prospective study, the prevalence of TTV in the nasopharyngeal aspirate (NPA) of hospitalized children <5 years old, with RIs and correlate them with outcomes and immune response.

PATIENTS AND METHODS

NPA was taken for testing of 16 respiratory viruses by reverse transcription-polymerase chain reaction (PCR), TTV PCR, and immunologic study.

RESULTS

Sixty hospitalized children with an RI were included. A total of 51/60 patients had positive common respiratory viral (CRV) identification. A total of 23/60 (38.3%) children were TTV+ in NPA. TTV+ patients had other CRVs in 100% of cases versus 78.3% in TTV- ( P = 0.029). The TTV+ patients tended to be older, have fever, and to need pediatric intensive care unit admission more often than TTV- patients. Abnormal chest radiograph was more frequent in the TTV+ patients, odds ratios 2.6 (95% CI: 1.3-5.2). The genetic expression of filaggrin (involved in epithelial barrier integrity) was lower in TTV+ patients; however, the levels of filaggrin in the NPA were increased.

CONCLUSIONS

TTV infection is common in children with RI and could be associated with abnormal imaging in radiograph, greater severity and an alteration in filaggrin gene expression and protein release.

Reduced miR-146a-5p Is a Biomarker of Infant Respiratory Diseases Contributing to Immune Dysregulation in Small Airway Epithelial Cells

Respiratory diseases such as bronchiolitis, and those with wheezing episodes, are highly important during infancy due to their potential chronicity. Immune response dysregulation is critical in perpetuating lung damage. Epigenetic modifications including microRNA (miRNA) post-transcriptional regulation are among the factors involved in alleviating inflammation. We evaluated the expression of miR-146a-5p, a previously described negative regulator of immunity, in infants with respiratory diseases, in order to study epigenetic regulation of the immune response. Nasopharyngeal aspirate (NPA) was obtained from infants with bronchiolitis (ongoing and post-disease) or with wheezing episodes in addition to healthy controls. Virus presence was determined by nested PCR, while miRNA and gene expression were studied in cells from NPAs using qPCR. Healthy small airway epithelial cells (SAECs) were used as an in vitro model. We observe a reduction in miR-146a-5p expression in infants with either of the two diseases compared to controls, suggesting the potential of this miRNA as a disease biomarker. Post-bronchiolitis, miR-146a-5p expression increases, though without reaching levels of healthy controls. MiR-146a-5p expression correlates inversely with the immune-related gene PTGS2, while its expression correlates directly with TSLP. When heathy donor SAECs are stimulated by poly:IC, we observe an increase in miR-146a-5p, with wounds having a synergistic effect. In conclusion, infants with respiratory diseases present reduced miR-146a-5p expression, possibly affecting immune dysregulation.

Alarmins and innate lymphoid cells 2 activation: A common pathogenetic link connecting respiratory syncytial virus bronchiolitis and later wheezing/asthma?

Severe respiratory syncytial virus (RSV) infection in infancy is associated with increased risk of recurrent wheezing in childhood. Both acute and long-term alterations in airway functions are thought to be related to inefficient antiviral immune response. The airway epithelium, the first target of RSV, normally acts as an immunological barrier able to elicit an effective immune reaction but may also be programmed to directly promote a Th2 response, independently from Th2 lymphocyte involvement. Recognition of RSV transcripts and viral replication intermediates by bronchial epithelial cells brings about release of TSLP, IL-33, HMGB1, and IL-25, dubbed "alarmins." These epithelial cell-derived proteins are particularly effective in stimulating innate lymphoid cells 2 (ILC2) to release IL-4, IL-5, and IL-13. ILC2, reflect the innate counterparts of Th2 cells and, when activate, are potent promoters of airway inflammation and hyperresponsiveness in RSV bronchiolitis and childhood wheezing/asthma. Long-term epithelial progenitors or persistent epigenetic modifications of the airway epithelium following RSV infection may play a pathogenetic role in the short- and long-term increased susceptibility to obstructive lung diseases in response to RSV in the young. Additionally, ILC2 function may be further regulated by RSV-induced changes in gut microbiota community composition that can be associated with disease severity in infants. A better understanding of the alarmin-ILC interactions in childhood might provide insights into the mechanisms characterizing these immune-mediated diseases and indicate new targets for prevention and therapeutic interventions.

Role of ILC2 in Viral-Induced Lung Pathogenesis

Innate lymphoid type-2 cells (ILC2) are a population of innate cells of lymphoid origin that are known to drive strong Type 2 immunity. ILC2 play a key role in lung homeostasis, repair/remodeling of lung structures following injury, and initiation of inflammation as well as more complex roles during the immune response, including the transition from innate to adaptive immunity. Remarkably, dysregulation of this single population has been linked with chronic lung pathologies, including asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrotic diseases (IPF). Furthermore, ILC2 have been shown to increase following early-life respiratory viral infections, such as respiratory syncytial virus (RSV) and rhinovirus (RV), that may lead to long-term alterations of the lung environment. The detrimental roles of increased ILC2 following these infections may include pathogenic chronic inflammation and/or alterations of the structural, repair, and even developmental processes of the lung. Respiratory viral infections in older adults and patients with established chronic pulmonary diseases often lead to exacerbated responses, likely due to previous exposures that leave the lung in a dysregulated functional and structural state. This review will focus on the role of ILC2 during respiratory viral exposures and their effects on the induction and regulation of lung pathogenesis. We aim to provide insight into ILC2-driven mechanisms that may enhance lung-associated diseases throughout life. Understanding these mechanisms will help identify better treatment options to limit not only viral infection severity but also protect against the development and/or exacerbation of other lung pathologies linked to severe respiratory viral infections.