Endoplasmic reticulum stress in airway hyperresponsiveness

Causal associations between pediatric asthma and united airways disease: a two-sample Mendelian randomization analysis

Background

Prior observational research has indicated a potential link between pediatric asthma and united airways disease (UAD). However, these findings could be subject to confounding factors and reverse causation. Therefore, our study utilizes Mendelian randomization (MR) method to further investigate the causal relationship between pediatric asthma and UAD.

Methods

We conducted a comprehensive two-sample Mendelian randomization (MR) analysis to investigate the association between pediatric asthma and seven groups of UAD, including chronic sinusitis, chronic rhinitis, nasopharyngitis and pharyngitis, chronic diseases of tonsils and adenoids, chronic laryngitis and laryngotracheitis, chronic bronchitis, bronchiectasis, chronic obstructive pulmonary disease (COPD). The present study employed a range of methods for two-sample MR analysis, including inverse variance weighted (IVW), MR-Egger regression, Simple mode, weighted median, and weighted models. The conclusion of the MR analysis primarily relies on the IVW results, while other analytical methods are utilized as supplementary evidence to ensure result robustness in this MR analysis. And sensitivity analyses were conducted, including heterogeneity test, horizontal pleiotropy test, MR-PRESSO test, and leave-one-out analysis to validate the results.

Results

The results of the MR analysis indicate significant causal effects of pediatric asthma on chronic rhinitis, nasopharyngitis and pharyngitis (IVW: OR = 1.15, 95%CI: 1.05-1.26, p-value = 0.003), chronic diseases of tonsils and adenoids (IVW: OR = 1.07, 95%CI: 1.00-1.15, p-value = 0.038), chronic bronchitis (IVW: OR = 1.51, 95%CI: 1.42-1.62, p-value <0.001), bronchiectasis (IVW: OR = 1.51, 95%CI: (1.30-1.75), p-value <0.001), and COPD (IVW: OR = 1.43, 95%CI: 1.34-1.51, p-value <0.001). However, no significant causal association was observed between pediatric asthma and chronic sinusitis (IVW: OR = 1.00, 95%CI: 1.00-1.00, p-value = 0.085), chronic laryngitis and laryngotracheitis (IVW: OR = 1.05, 95%CI: 0.90-1.21, p-value = 0.558).

Conclusion

Our findings support a potential causal relationship between pediatric asthma and UAD, suggesting that pediatric asthma may be a potential risk factor for various UAD.

Research on the Mechanism and Application of Acupuncture Therapy for Asthma: A Review

Asthma is a high-risk disease based on airway hyperresponsiveness (AHR). In this review, we found that there are many studies on clinical therapy for asthma that focus on the efficacy of acupuncture therapy and its mechanisms, including the functional connectivity of different brain regions, with the aid of functional magnetic resonance imaging (fMRI), immune responses/cell recognition (innate lymphoid cells and balance of Th1/Th2 and Treg/Th17), intracellular mechanism (autophagy, endoplasmic reticulum stress, and epigenetic alteration), and ligand-receptor/chemical signaling pathway (neurotransmitter, hormone, and small molecules). In this review, we summarized the clinical and experimental evidence for the mechanisms of acupuncture therapy in asthma to offer insights into drug discovery and clinical therapy. Given the paucity of clinical studies on the mechanisms of acupuncture in the treatment of asthma, this review notably included studies based on animal models to investigate the mechanisms of acupuncture in the treatment of asthma.

Edaravone alleviated allergic airway inflammation by inhibiting oxidative stress and endoplasmic reticulum stress

Oxidative stress and endoplasmic reticulum stress (ERS) was associated with the development of asthma. Edaravone (EDA) plays a classical role to prevent the occurrence and development of oxidative stress-related diseases. Herein, we investigated the involvement and signaling pathway of EDA in asthma, with particular emphasis on its impact on type 2 innate lymphoid cells (ILC2) and CD4+T cells, and then further elucidated whether EDA could inhibit house dust mite (HDM)-induced allergic asthma by affecting oxidative stress and ERS. Mice received intraperitoneally injection of EDA (10 mg/kg, 30 mg/kg), dexamethasone (DEX) and N-acetylcysteine (NAC), with the latter two used as positive control drugs. DEX and high dose of EDA showed better therapeutic effects in alleviating airway inflammation and mucus secretion in mice, along with decreasing eosinophils and neutrophils in bronchoalveolar lavage fluid (BALF) than NAC. Further, the protein levels of IL-33 in lung tissues were inhibited by EDA, leading to reduced activation of ILC2s in the lung. EDA treatment alleviated the activation of CD4+ T cells in lung tissues of HDM-induced asthmatic mice and reduced Th2 cytokine secretion in BALF. ERS-related markers (p-eIF2α, IRE1α, CHOP, GRP78) were decreased after treatment of EDA compared to HDM group. Malondialdehyde (MDA), glutathione (GSH), hydrogen peroxide (H2O2), and superoxide dismutase (SOD) were detected to evaluate the oxidant stress in lung tissues. EDA showed a protective effect against oxidant stress. In conclusion, our findings demonstrated that EDA could suppress allergic airway inflammation by inhibiting oxidative stress and ERS, suggesting to serve as an adjunct medication for asthma in the future.

Protective effects of myricetin on airway inflammation and oxidative stress in ovalbumin-induced asthma mice

Myricetin, a flavonoid isolated from many edible vegetables and fruits, has multiple biological effects, including anti-inflammatory and anti-tumor effects. Myricetin could inhibit mast cell degranulation in vitro, and it reduced the eosinophil content in bronchoalveolar lavage fluid (BALF) of ovalbumin (OVA)-sensitized mice. However, it remains unclear whether myricetin alleviates airway hyperresponsiveness (AHR), airway inflammation, and oxidative stress in asthma. Here, we investigated whether myricetin attenuated AHR, airway inflammation, and eosinophil infiltration in lungs of asthmatic mice. Mice were sensitized with OVA, then injected intraperitoneally with myricetin to investigate anti-inflammatory and antioxidant effects of myricetin. Moreover, we examined its effects on human bronchial epithelial BEAS-2B cells stimulated with TNF-α and IL-4, in vitro. Myricetin effectively mitigated eosinophil infiltration, AHR, and goblet cell hyperplasia in lung, and it reduced Th2 cytokine expression in BALF from asthmatic mice. Myricetin effectively promoted glutathione and superoxide dismutase productions and mitigated malondialdehyde expressions in mice by promoting Nrf2/HO-1 expression. Myricetin also reduced the production of proinflammatory cytokines, eotaxins, and reactive oxygen species in BEAS-2B cells. Myricetin effectively suppressed ICAM-1 expression in inflammatory BEAS-2B cells, which suppressed monocyte cell adherence. These results suggested that myricetin could effectively improve asthma symptoms, mainly through blocking Th2-cell activation, which reduced oxidative stress, AHR, and airway inflammation.

Fine particulate matter promotes airway inflammation and mucin production by activating endoplasmic reticulum stress and the IRE1α/NOD1/NF‑κB pathway

Fine particulate matter (PM2.5) is a type of small particle that is <2.5 µm in diameter that may cause airway inflammation. Thus, the present study aimed to explore the effects of PM2.5 on endoplasmic reticulum (ER) stress and airway inflammation in human airway epithelial cells. For this purpose, HBE135‑E6E7 airway epithelial cells were cultured and exposed to specific concentrations of PM2.5 for various periods of time, and cell viability was determined using a Cell Counting Kit‑8 assay. The results of the present study demonstrated that exposure to PM2.5 increased the mRNA and protein expression levels of interleukin (IL)‑6, tumor necrosis factor (TNF)‑α and mucin 5AC (MUC5AC). Moreover, the expression levels of ER stress‑related proteins, such as glucose‑regulated protein 78, CCAAT‑enhancer binding protein homologous protein, activating transcription factor 6, protein kinase R‑like ER kinase (PERK), phosphorylated (p‑)PERK, inositol‑requiring enzyme 1α (IRE1α) and p‑IRE1α, and nucleotide‑binding oligomerization domain 1 (NOD1) expression levels were increased following exposure to PM2.5. Transfection with IRE1α small interfering RNA (siRNA) led to the increased production of IL‑6, TNF‑α and MUC5AC. Moreover, the expression of NOD1 and the translocation of NF‑κB p65 were inhibited following transfection with IRE1α siRNA. In addition, the results of the present study demonstrated that transfection with NOD1 siRNA decreased the production of IL‑6, TNF‑α and MUC5AC, and decreased the translocation of NF‑κB p65. The expression levels of IL‑6, TNF‑α and MUC5AC were increased in the HBE135‑E6E7 cells following treatment with C12‑iE‑DAP, a NOD1 agonist. Moreover, treatment with C12‑iE‑DAP led to the activation of NF‑κB p65. Collectively, the results of the present study suggest that PM2.5 promotes airway inflammation and mucin production by activating ER stress in HBE135‑E6E7 airway epithelial cells, and that the IRE1α/NOD1/NF‑κB pathway may be involved in this process.

The Effects of a Transgelin-2 Agonist Administered at Different Times in a Mouse Model of Airway Hyperresponsiveness

Airway hyperresponsiveness (AHR) is one of the most important features of asthma. Our previous study showed that inhaled transgelin-2 agonist, TSG12, effectively reduced pulmonary resistance in a mouse model of asthma in a dose-dependent manner. However, the optimal administration time of TSG12 to reduce AHR and the pharmacological effects are still unclear. In this study, the effects of TSG12 inhalation before and during AHR occurrence were examined. The results showed that the pulmonary resistance was reduced by 57% and the dynamic compliance was increased by 46% in the TSG12 Mch group (atomize TSG12 10 min before methacholine, p &lt; 0.05 vs. model). The pulmonary resistance was reduced by 61% and the dynamic compliance was increased by 47% in the TSG12 + Mch group (atomize TSG12 and methacholine together, p &lt; 0.05 vs. model). Quantitative real-time PCR showed that the gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 6.4-, 1.9-, and 2.8-fold, respectively, in the TSG12 Mch group. The gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 3.2-, 1.4-, and 1.9-fold, respectively, in the TSG12 + Mch group. The results suggested that TSG12 effectively reduces pulmonary resistance when TSG12 inhalation occurred both before and during AHR occurrence. Gene expression levels of transgelin-2 and myosin light chain were significantly up-regulated when TSG12 inhalation occurred before AHR occurrence. This study may provide a basis for the administration time of TSG12 for asthma treatment in the future.