Effect of HMGB1 on monocyte immune function in respiratory syncytial virus bronchiolitis

High-mobility group box 1 emerges as a therapeutic target for asthma

High-mobility group box 1 (HMGB1) is a highly conserved nonhistone nuclear protein found in the calf thymus and participates in a variety of intracellular processes such as DNA transcription, replication and repair. In the cytoplasm, HMGB1 promotes mitochondrial autophagy and is involved in in cellular stress response. Once released into the extracellular, HMGB1 becomes an inflammatory factor that triggers inflammatory responses and a variety of immune responses. In addition, HMGB1 binding with the corresponding receptor can activate the downstream substrate to carry out several biological effects. Meanwhile, HMGB1 is involved in various signaling pathways, such as the HMGB1/RAGE pathway, HMGB1/NF-κB pathway, and HMGB1/JAK/STAT pathway, which ultimately promote inflammation. Moreover, HMGB1 may be involved in the pathogenesis of asthma by regulating downstream signaling pathways through corresponding receptors and mediates a number of signaling pathways in asthma, such as HMGB1/TLR4/NF-κB, HMGB1/RAGE, HMGB1/TGF-β, and so forth. Accordingly, HMGB1 emerges as a therapeutic target for asthma.

Monocyte and neutrophil to lymphocyte ratios in hospitalized children with RSV bronchiolitis

OBJECTIVE

Acute bronchiolitis is the most common cause of hospitalization in young children. Data on monocyte-to-lymphocyte-ratio (MLR) and neutrophil-to-lymphocyte-ratio (NLR) as biomarkers are limited. We aim to evaluate these ratios in children hospitalized with respiratory syncytial virus (RSV) bronchiolitis and their value as biomarkers for severe clinical outcomes.

STUDY DESIGN

A single-center retrospective cohort study of children aged <2 years hospitalized due to RSV bronchiolitis, between January 2018 and March 2022, with a complete blood count upon admission. We divided the cohort into quartiles based on MLR and NLR values. We examined associations between quartiles and four clinical severity outcomes.

RESULTS

A total of 2038 children (median age: 4.4 months, IQR: 1.9-9.8) were included in the study. The median MLR and NLR values for quartiles 1-4 were 0.14, 0.22, 0.30, 0.47, and 0.37, 0.70, 1.16, 2.29, respectively. Children with higher MLR had higher hospitalization rates to the pediatric intensive care unit (PICU) (Q1 2.4%, Q4 9.4%, p < .001), extended hospital stays (Q1 19.4%, Q4 32%, p < .001), and lower minimal oxygen saturation (Q1 90%, Q4 87%, p < .001). Cut-off values of 0.34 for MLR and 0.67 for NLR optimally identified PICU admissions. In a model accounting for age and sex, the fourth MLR quartile had an RR of 3.4 (95% CI: 1.76-7.22) and successfully predicted PICU admissions (area under the curve = 0.73; 95% CI: 0.681-0.789).

CONCLUSIONS

MLR and NLR are potential biomarkers for identifying children with RSV bronchiolitis at a higher risk for severe outcomes, specifically PICU admission.

Oxidative stress and ROS-mediated cellular events in RSV infection: potential protective roles of antioxidants

Respiratory syncytial virus (RSV), a member of the Pneumoviridae family, can cause severe acute lower respiratory tract infection in infants, young children, immunocompromised individuals and elderly people. RSV is associated with an augmented innate immune response, enhanced secretion of inflammatory cytokines, and necrosis of infected cells. Oxidative stress, which is mainly characterized as an imbalance in the production of reactive oxygen species (ROS) and antioxidant responses, interacts with all the pathophysiologic processes above and is receiving increasing attention in RSV infection. A gradual accumulation of evidence indicates that ROS overproduction plays an important role in the pathogenesis of severe RSV infection and serves as a major factor in pulmonary inflammation and tissue damage. Thus, antioxidants seem to be an effective treatment for severe RSV infection. This article mainly reviews the information on oxidative stress and ROS-mediated cellular events during RSV infection for the first time.

Acteoside attenuates RSV-induced lung injury by suppressing necroptosis and regulating metabolism

Background: Necroptosis and inflammation are closely related to the pathogenesis of respiratory syncytial virus (RSV). Acteoside (AC), a natural phenylpropanoid glycoside from Kuding Tea, has significant anti-RSV effect. However, the roles of AC on RSV-induced lung necroptosis and inflammation are yet to be elucidated.

Methods: The effects of AC were investigated in BALB/c mice and A549 cells. Lung histopathology was observed through H&amp;E staining. The viral titer was assessed via plaque assay. The RSV-F expression was determined by RT-qPCR and immunohistochemistry assay. The levels of cytokines were detected by ELISA and RT-qPCR. The necroptosis rate and mitochondrial membrane potential were evaluated via flow cytometry. The expressions of HMGB1/NF-κB and RIP1/RIP3/MLKL/PGAM5/DRP1 were detected by western blot. Additionally, untargeted metabolomics was conducted to investigate the metabolic profiles and related metabolic pathways via Gas Chromatography-Mass Spectrometry.

Results: The results showed that compared with the RSV-infected group, AC treatment significantly attenuated lung pathological damage, virus replication, and cytokines levels. AC also alleviated RSV-induced necroptosis and mitochondrial dysfunction in vitro and in vivo. Moreover, AC treatment down-regulated the expression of HMGB1, p-Iκbα/Iκbα, p-p65/p65, RIP1, RIP3, MLKL, PGAM5, and DRP1. Furthermore, metabolomic analyses suggested that the perturbations in major metabolites of AC therapy were related to variations in amino acid and energy metabolism.

Conclusion: Our findings validated the beneficial effects of AC in suppressing necroptosis and regulating metabolism, suggesting AC may be a new drug candidate for RSV infection.

Depression of long non-coding RNA SOX2 overlapping transcript attenuates lipopolysaccharide-induced injury in bronchial epithelial cells via miR-455-3p/phosphatase and tensin homolog axis and phosphatidylinositol 3-kinase/protein kinase B pathway

Airway inflammation is associated with various respiratory diseases, and previous research has confirmed that long non-coding RNAs (lncRNAs) play imperative roles in inflammatory responses. However, the function of lncRNA SOX2 overlapping transcript (SOX2-OT) in airway inflammation remains enigmatic. This study aimed to investigate the effects of SOX2-OT on lipopolysaccharide (LPS)–induced cell injury in human bronchial epithelial cells, BEAS-2B, and its potential mechanisms. The results showed increased cell apoptotic ratio, production of inflammatory cytokines, higher expression of adhesion molecules and activation of NF-κB in LPS–stimulated BEAS-2B cells. In LPS–stimulated BEAS-2B cells, SOX2-OT up-regulation and miR-455-3p down-regulation emerged simultaneously. SOX2-OT knockdown or miR-455-3p over-expression restrained LPS–induced inflammation and injury. SOX2-OT sponged to miR-455-3p and functioned as a ceRNA. In addition, phosphatase and tensin homolog (PTEN) served as an endogenous target of miR-455-3p to modulate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway and disturb the alleviated consequence of miR-455-3p over-expression on LPS–induced BEAS-2B cell inflammation and cell injury. Our data demonstrated that SOX2-OT plays a pivotal role in LPS–induced inflammation and injury in BEAS-2B cells and exerts its function through the miR-455-3p/PTEN axis and modulation of the PI3K/AKT pathway.