MicroRNA-21 Inhibition Suppresses Alveolar M2 Macrophages in an Ovalbumin-Induced Allergic Asthma Mice Model

Research progress on the relationship between phenotype and signaling pathways of pulmonary macrophages and asthma

OBJECTIVE

The purpose of this study is to systematically investigate the different phenotypes and functional analyses of macrophages in lung tissue.

DATA SOURCES

A search was performed using three databases (Web of Science, Science Direct, and MEDLINE) for all relevant studies published from January 1, 2019, to December 31, 2023.

STUDY SELECTIONS

This systematic review complied with the PRlSMA document's requirements, including studies related to the signaling pathway relationship between pulmonary macrophages and asthma phenotype. The search includedstudies published in English or French lanquage, and was based on title, abstract, and complete textDocuments not meeting inclusion requirements were excluded.

RESULTS

We have identified studies published within the past five years that meet the criteria for inclusion in this review. We found that asthma is a heterogeneous chronic inflammatory lung disease, and lung tissue macrophages are important immune cells in the respiratory tract. Pulmonary macrophages are also heterogeneous, as they have different subgroups with varying effector functions depending on the environment. They have different phenotypes and biological functions in different disease environments. The phenotypic changes of pulmonary macrophages occur during asthma, and the study of the different phenotypes and functions of macrophages in lung tissue is of great significance for treatment.

CONCLUSIONS

This review summarizes current literature and provides a detailed introduction to the role of macrophages as key inflammatory mediators in the pathogenesis of asthma, as well as existing knowledge gaps. In addition, we propose that regulatory macrophages may prevent the development of asthma by producing IL-10, and regulating the polarization of pulmonary macrophages may be a new direction for asthma treatment.

Mesenchymal Stromal Cell Therapy Alleviates Ovalbumin-Induced Chronic Airway Remodeling by Suppressing M2 Macrophage Polarization

Chronic asthma is characterized by airway hyperresponsiveness, inflammation, and remodeling. Previous studies have shown that mesenchymal stromal/stem cells (MSCs) exert anti-inflammatory effects on asthma via regulation of the immune cells. However, the therapeutic mechanism of MSCs, especially the mechanism of airway remodeling in chronic asthma, remains to be elucidated. Here, we aimed to investigate the therapeutic effect of MSCs on airway remodeling in chronic asthma and explored the mechanisms by analyzing the polarization phenotype of macrophages in the lungs. We established a mouse model of chronic asthma induced by ovalbumin (OVA) and evaluated the effect of MSCs on airway remodeling. The data showed that MSCs treatment before the challenge exerted protective effects on OVA-induced chronic asthma, i.e., decreased the inflammatory cell infiltration, Th2 cytokine levels, subepithelial extracellular matrix deposition, and transforming growth factor β (TGF-β)/Smad signaling. Additionally, we found that MSCs treatment markedly suppressed macrophage M2 polarization in lung tissue. At the same time, MSCs treatment inhibited NF-κB p65 nuclear translocation, ER stress, and oxidative stress in the OVA-induced chronic allergic airway remodeling mice model. In conclusion, these results demonstrated that MSCs treatment prevents OVA-induced chronic airway remodeling by suppressing macrophage M2 polarization, which may be associated with the dual inhibition of ER stress and oxidative stress. This discovery may provide a new theoretical basis for the future clinical application of MSCs.

The effect of bioactivity of airway epithelial cells using methacrylated gelatin scaffold loaded with exosomes derived from bone marrow mesenchymal stem cells

The current evidence provides support for the involvement of bone marrow mesenchymal stem cells (BMSCs) in the regulation of airway epithelial cells. However, a comprehensive understanding of the underlying biological mechanisms remains elusive. This study aimed to isolate and characterize BMSC-derived exosomes (BMSC-Exos) and epithelial cells (ECs) through primary culture. Subsequently, the impact of BMSC-Exos on ECs was assessed in vitro, and sequencing analysis was conducted to identify potential molecular mechanisms involved in these interactions. Finally, the efficacy of BMSC-Exos was evaluated in animal models in vivo. In this study, primary BMSCs and ECs were efficiently isolated and cultured, and high-purity Exos were obtained. Upon uptake of BMSC-Exos, ECs exhibited enhanced proliferation (p < .05), while migration showed no difference (p > .05). Notably, invasion demonstrated significant difference (p < .05). Sequencing analysis suggested that miR-21-5p may be the key molecule responsible for the effects of BMSC-Exos, potentially mediated through the MAPK or PI3k-Akt signaling pathway. The in vivo experiments showed that the presence of methacrylated gelatin (GelMA) loaded with BMSC-Exos in composite scaffold significantly enhanced epithelial crawling in the patches in comparison to the pure decellularized group. In conclusion, this scheme provides a solid theoretical foundation and novel insights for the research and clinical application of tracheal replacement in the field of tissue engineering.

Celastrol alleviates airway hyperresponsiveness and inflammation in obese asthma through mediation of alveolar macrophage polarization

Obese asthma is a unique asthma phenotype that decreases sensitivity to inhaled corticosteroids, and currently lacks efficient therapeutic medication. Celastrol, a powerful bioactive substance obtained naturally from the roots of Tripterygium wilfordii, has been reported to possess the potential effect of weight loss in obese individuals. However, its role in the treatment of obese asthma is not fully elucidated. In the present study, diet-induced obesity (DIO) mice were used with or without ovalbumin (OVA) sensitization, the therapeutic effects of celastrol on airway hyperresponsiveness (AHR) and airway inflammation were examined. We found celastrol significantly decreased methacholine-induced AHR in obese asthma, as well as reducing the infiltration of inflammatory cells and goblet cell hyperplasia in the airways. This effect was likely due to the inhibition of M1-type alveolar macrophages (AMs) polarization and the promotion of M2-type macrophage polarization. In vitro, celastrol yielded equivalent outcomes in Lipopolysaccharide (LPS)-treated RAW264.7 macrophage cells, featuring a reduction in the expression of M1 macrophage makers (iNOS, IL-1β, TNF-α) and heightened M2 macrophage makers (Arg-1, IL-10). Mechanistically, the PI3K/AKT signaling pathway has been implicated in these processes. In conclusion, we demonstrated that celastrol assisted in mitigating various parameters of obese asthma by regulating the balance of M1/M2 AMs polarization.

Blocking group 2 innate lymphoid cell activation and macrophage M2 polarization: potential therapeutic mechanisms in ovalbumin-induced allergic asthma by calycosin

BACKGROUND

Calycosin, a flavonoid compound extracted from Astragalus membranaceus, has shown anti-asthma benefits in house dust mite-induced asthma. Recent studies have suggested that innate-type cells, including group 2 innate lymphoid cells (ILC2s) and macrophages, serve as incentives for type 2 immunity and targets for drug development in asthma. This work focuses on the effects of calycosin on the dysregulated ILC2s and macrophages in allergic asthma.

METHODS

In vivo, the asthmatic mouse model was established with ovalbumin (OVA) sensitization and challenge, and calycosin was intraperitoneally administered at doses of 20 and 40 mg/kg. In vivo, mouse primary ILC2s were stimulated with interleukin (IL)-33 and mouse RAW264.7 macrophages were stimulated with IL-4 and IL-13 to establish the cell models. Cells were treated with calycosin at doses of 5 and 10 µM.

RESULTS

In vivo, we observed significantly reduced numbers of eosinophils, neutrophils, monocyte macrophages and lymphocytes in the bronchoalveolar lavage fluid (BALF) of OVA-exposed mice with 40 mg/kg calycosin. Histopathological assessment showed that calycosin inhibited the airway inflammation and remodeling caused by OVA. Calycosin markedly decreased the up-regulated IL-4, IL-5, IL-13, IL-33, and suppression tumorigenicity 2 (ST2) induced by OVA in BALF and/or lung tissues of asthmatic mice. Calycosin repressed the augment of arginase 1 (ARG1), IL-10, chitinase-like 3 (YM1) and mannose receptor C-type 1 (MRC1) levels in the lung tissues of asthmatic mice. In vivo, calycosin inhibited the IL-33-induced activation as well as the increase of IL-4, IL-5, IL-13 and ST2 in ILC2s. Calycosin also repressed the increase of ARG1, IL-10, YM1 and MRC1 induced by IL-4 and IL-13 in RAW264.7 macrophages. In addition, we found that these changes were more significant in 40 mg/kg calycosin treatment than 20 mg/kg calycosin.

CONCLUSIONS

Collectively, this study showed that calycosin might attenuate OVA-induced airway inflammation and remodeling in asthmatic mice via preventing ILC2 activation and macrophage M2 polarization. Our study might contribute to further study of asthmatic therapy.

miR-21-5p Modulates Airway Inflammation and Epithelial-Mesenchymal Transition Processes in a Mouse Model of Combined Allergic Rhinitis and Asthma Syndrome

INTRODUCTION

Combined allergic rhinitis and asthma syndrome (CARAS) is a concurrent allergic symptom of diseases of allergic rhinitis and asthma. However, the mechanism of CARAS remains unclear. The study aimed to investigate the impact of microRNA-21 (miR-21) on CARAS via targeting poly (ADP-ribose) polymerase-1 (PARP-1) and phosphoinositide 3-kinase (PI3K)/AKT pathways.

METHODS

The levels of miR-21-5p and PARP-1 in CARAS patients were detected by quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). An ovalbumin-sensitized mouse model of CARAS was established. And knock down of miR-21-5p was constructed by intranasally administering with miR-21-5p shRNA-encoding adeno-associated virus vector. Airway resistance and airway inflammatory response were detected. ELISA was used to evaluate IL-4/IL-5/IL-13 levels in bronchoalveolar lavage fluid (BALF). Expression levels of E-cadherin, fibronectin, and α-SMA were determined using Western blotting. The levels of PARP-1 and the activation of PI3K/AKT were assayed.

RESULTS

Downregulation of miR-21-5p relieved pathophysiological symptoms of asthma including airway hyperreactivity and inflammatory cell infiltration. Downregulation of miR-21-5p significantly reduced the levels of IL4, IL-5, and IL-13 in BALF. Additionally, downregulation of miR-21-5p inhibited the epithelial-mesenchymal transition (EMT) process in CARAS mice. Furthermore, miR-21-5p regulated PARP-1 and was involved in PI3K/AKT activation in CARAS mice.

CONCLUSION

Downregulation of miR-21-5p ameliorated CARAS-associated lung injury by alleviating airway inflammation, inhibiting the EMT process, and regulating PARP-1/PI3K/AKT in a mouse model of CARAS.

The Roles of MicroRNAs in Asthma and Emerging Insights into the Effects of Vitamin D3 Supplementation

Asthma is one of the most common chronic non-communicable diseases worldwide, characterized by variable airflow limitation secondary to airway narrowing, airway wall thickening, and increased mucus resulting from chronic inflammation and airway remodeling. Current epidemiological studies reported that hypovitaminosis D is frequent in patients with asthma and is associated with worsening the disease and that supplementation with vitamin D3 improves asthma symptoms. However, despite several advances in the field, the molecular mechanisms of asthma have yet to be comprehensively understood. MicroRNAs play an important role in controlling several biological processes and their deregulation is implicated in diverse diseases, including asthma. Evidence supports that the dysregulation of miR-21, miR-27b, miR-145, miR-146a, and miR-155 leads to disbalance of Th1/Th2 cells, inflammation, and airway remodeling, resulting in exacerbation of asthma. This review addresses how these molecular mechanisms explain the development of asthma and its exacerbation and how vitamin D3 may modulate these microRNAs to improve asthma symptoms.

Regulation of Macrophage Polarization in Allergy by Noncoding RNAs

Allergy is a type 2 immune reaction triggered by antigens known as allergens, including food and environmental substances such as peanuts, plant pollen, fungal spores, and the feces and debris of mites and insects. Macrophages are myeloid immune cells with phagocytic abilities that process exogenous and endogenous antigens. Upon activation, they can produce effector molecules such as cytokines as well as anti-inflammatory molecules. The dysregulation of macrophage function can lead to excessive type 1 inflammation as well as type 2 inflammation, which includes allergic reactions. Thus, it is important to better understand how macrophages are regulated in the pathogenesis of allergies. Emerging evidence highlights the role of noncoding RNAs (ncRNAs) in macrophage polarization, which in turn can modify the pathogenesis of various immune-mediated diseases, including allergies. This review summarizes the current knowledge regarding this topic and considers three classes of ncRNAs: microRNAs, long ncRNAs, and circular ncRNAs. Understanding the roles of these ncRNAs in macrophage polarization will provide new insights into the pathogenesis of allergies and identify potential novel therapeutic targets.

FoxO4 mediates macrophage M2 polarization by promoting LXA4R expression in an ovalbumin-induced allergic asthma model in mice

BACKGROUND

Asthma imposes a heavy burden due to its high prevalence. Forkhead box O4 (FoxO4) proteins participate in the modulation of cell progression. However, the role and mechanism of FoxO4 in asthma remains uncharted.

METHODS

An allergic asthma model was constructed by the induction of ovalbumin and interleukin (IL)-4 in mice and monocyte/macrophage-like Raw264.7 cells, respectively. The role and mechanism of FoxO4 in asthma was determined by pathological staining, immunofluorescence assay, measurement of inflammatory cells in the blood, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blot analysis, and flow cytometry.

RESULTS

Ovalbumin treatment triggered an obvious inflammatory cell infiltration with a prominent increase in F4/80⁺ cell numbers. The relative messenger RNA (mRNA) and protein expressions of FoxO4 were increased in both ovalbumin-induced mice and interleukin-4 (IL-4)-induced Raw264.7 cells. Inhibition of FoxO4 via AS1842856 reduced inflammatory cell infiltration, the number of Periodic Acid Schiff+ (PAS+) goblet cells, the numbers of inflammatory cells in the blood, and the airway resistance in ovalbumin-induced mice. Besides, interference of FoxO4 decreased the number of F4/80⁺CD206⁺ cells, and the relative protein expressions of CD163 and Arg1 in vivo and in vitro. Mechanically, suppression of FoxO4 diminished the relative mRNA and protein expressions of LXA4R in both ovalbumin-induced mice and IL-4-induced Raw264.7 cells. Overexpression of LXA4R reversed the outcomes caused by repression of FoxO4, including airway resistance, the number of F4/80+ cells, the proportion of CD206+ cells in ovalbumin-induced mice, and the proportion of F4/80⁺CD206⁺ cells in IL-4-induced Raw264.7 cells.

CONCLUSION

FoxO4/LXA4R axis mediated macrophage M2 polarization in allergic asthma.

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in allergic airway inflammation

As a pattern recognition receptor which activates innate immune system, toll-like receptor 2 (TLR2) has been reportedly mediates allergic airway inflammation (AAI), yet the underlying mechanism remains elusive. Here, in a murine AAI model, TLR2^-/- mice showed decreased airway inflammation, pyroptosis and oxidative stress. RNA-sequencing revealed that allergen-induced hif1 signaling pathway and glycolysis were significantly downregulated when TLR2 was deficient, which were confirmed by lung protein immunoblots. Glycolysis inhibitor 2-Deoxy-d-glucose (2-DG) inhibited allergen-induced airway inflammation, pyroptosis, oxidative stress and glycolysis in wild type (WT) mice, while hif1α stabilizer ethyl 3,4-dihydroxybenzoate (EDHB) restored theses allergen-induced changes in TLR2^-/- mice, indicating TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in AAI. Moreover, upon allergen challenge, lung macrophages were highly activated in WT mice but were less activated in TLR2^-/- mice, 2-DG replicated while EDHB reversed such effect of TLR2 deficiency on lung macrophages. Likewise, both in vivo and ex vivo WT alveolar macrophages (AMs) exhibited higher TLR2/hif1α expression, glycolysis and polarization activation in response to ovalbumin (OVA), which were all inhibited in TLR2^-/- AMs, suggesting AMs activation and metabolic switch are dependent on TLR2. Finally, depletion of resident AMs in TLR2^-/- mice abolished while transfer of TLR2^-/- resident AMs to WT mice replicated the protective effect of TLR2 deficiency on AAI when administered before allergen challenge. Collectively, we suggested that loss of TLR2-hif1α-mediated glycolysis in resident AMs ameliorates allergic airway inflammation that inhibits pyroptosis and oxidative stress, therefore the TLR2-hif1α-glycolysis axis in resident AMs may be a novel therapeutic target for AAI.

Electroacupuncture-induced activation of GABAergic system alleviates airway inflammation in asthma model by suppressing TLR4/MyD88/NF-κB signaling pathway

BACKGROUND

Electroacupuncture (EA) has been shown to attenuate airway inflammation in asthmatic mice; however, the underlying mechanism is not fully understood. Studies have shown that EA can significantly increase the inhibitory neurotransmitter γ-aminobutyric acid (GABA) content in mice, and can also increase the expression level of GABA type A receptor (GABAAR). Furthermore, activating GABAAR may relieve inflammation in asthma by suppressing toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-kappa B (NF-κB) signaling pathway. Therefore, this study aimed to investigate the role of GABAergic system and TLR4/MyD88/NF-κB signaling pathway in asthmatic mice treated with EA.

METHODS

A mouse model of asthma was established, and a series of methods including Western blot and histological staining assessment were employed to detect the level of GABA, and expressions of GABAAR and TLR4/MyD88/NF-κB in lung tissue. In addition, GABAAR antagonist was used to further validate the role and mechanism of GABAergic system in mediating the therapeutic effect of EA in asthma.

RESULTS

The mouse model of asthma was established successfully, and EA was verified to alleviate airway inflammation in asthmatic mice. The release of GABA and the expression of GABAAR were significantly increased in asthmatic mice treated with EA compared with untreated asthmatic mice ( P  < 0.01), and the TLR4/MyD88/NF-κB signaling pathway was down-regulated. Moreover, inhibition of GABAAR attenuated the beneficial effects of EA in asthma, including the regulation of airway resistance and inflammation, as well as the inhibitory effects on TLR4/MyD88/NF-κB signaling pathway.

CONCLUSION

Our findings suggest that GABAergic system may be involved in mediating the therapeutic effect of EA in asthma, possibly by suppressing the TLR4/MyD88/NF-κB signaling pathway.

Recent miRNA Research in Asthma

PURPOSE OF REVIEW

The study of microRNA in asthma has revealed a vibrant new level of gene regulation underlying asthma pathology. Several miRNAs have been shown to be important in asthma, influencing various biological mechanisms which lead to asthma pathology and symptoms. In addition, miRNAs have been proposed as biomarkers of asthma affection status, asthma severity, and asthma treatment response. We review all recent asthma-miRNA work, while also presenting comprehensive tables of all miRNA results related to asthma.

RECENT FINDINGS

We here reviewed 63 recent studies published reporting asthma and miRNA research, and an additional 14 reviews of the same. We summarized the information for both adult and childhood asthma, as well as research on miRNAs in asthma-COPD overlap syndrome (ACOs), and virus-induced asthma exacerbations. We attempted to present a comprehensive collection of recently published asthma-associated miRNAs as well as tables of all published asthma-related miRNA results.

Blockade of Mbd2 by siRNA-loaded liposomes protects mice against OVA-induced allergic airway inflammation via repressing M2 macrophage production

Objective

To address the role of methyl-CpG-binding domain 2 (MBD2) in the pathogenesis of asthma and its potential as a target for the asthmatic therapy.

Methods

Studies were conducted in asthmatic patients and macrophage-specific Mbd2 knockout mice to dissect the role of MBD2 in asthma pathogenesis. Additionally, RNAi-based therapy with Mbd2 siRNA-loaded liposomes was conducted in an ovalbumin (OVA)-induced allergic airway inflammation mouse model.

Results

Asthmatic patients and mice challenged with OVA exhibited upregulated MBD2 expression in macrophages, especially in alternatively activated (M2) macrophages. In particular, macrophage-specific knockout of Mbd2 protected mice from OVA-induced allergic airway inflammation and suppressed the M2 program. Notably, intratracheal administration of liposomes carrying Mbd2 siRNA decreased the expression of Mbd2 and prevented OVA-induced allergic airway inflammation in mice, as indicated by the attenuated airway inflammation and mucus production.

Conclusions

The above data indicate that Mbd2 implicates in the pathogenesis of asthma predominantly by regulating the polarization of M2 macrophages, which supports that Mbd2 could be a viable target for treatment of asthma in clinical settings.

Role of Obesity in Inflammation and Remodeling of Asthmatic Airway

Obesity is considered as an important risk factor for the onset of asthma and plays a key role in enhancing the disease's severity. Obese asthmatic individuals represent a distinct phenotype of asthma that is associated with additional symptoms, more severe exacerbation, decreased response to standard medication, and poor quality of life. Obesity impairs the function of the lung airway in asthmatic individuals, leading to increased inflammation and severe remodeling of the bronchus; however, the molecular events that trigger such changes are not completely understood. In this manuscript, we review the current findings from studies that focused on understanding the role of obesity in modulating the functions of airway cells, including lung immune cells, epithelial cells, smooth muscle cells, and fibroblasts, leading to airway inflammation and remodeling. Finally, the review sheds light on the current knowledge of different therapeutic approaches for treating obese asthmatic individuals. Given the fact that the prevalence of asthma and obesity has been increasing rapidly in recent years, it is necessary to understand the molecular mechanisms that play a role in the disease pathophysiology of obese asthmatic individuals for developing novel therapies.

Epithelial‑derived exosomes promote M2 macrophage polarization via Notch2/SOCS1 during mechanical ventilation

Alveolar macrophages (AMs) play an essential role in ventilator-induced lung injury (VILI). Exosomes and their cargo, including microRNAs (miRNAs/miRs) serve as regulators of the intercellular communications between macrophages and epithelial cells (ECs), and are involved in maintaining homeostasis in lung tissue. The present study found that exosomes released by ECs subjected to cyclic stretching promoted M2 macrophage polarization. It was demonstrated that miR-21a-5p, upregulated in epithelial-derived exosomes, increased the percentage of M2 macrophages by suppressing the expression of Notch2 and the suppressor of cytokine signaling 1 (SOCS1). The overexpression of Notch2 decreased the percentage of M2 macrophages. However, these effects were reversed by the downregulation of SOCS1. The percentage of M2 macrophages was increased in both short-term high- and low-tidal-volume mechanical ventilation, and the administration of exosomes-derived from cyclically stretched ECs had the same function. However, the administration of miR-21a-5p antagomir decreased M2 macrophage activation induced by cyclically stretched ECs or ventilation. Thus, the present study demonstrates that the intercellular transferring of exosomes from ECs to AMs promotes M2 macrophage polarization. Exosomes may prove to be a novel treatment for VILI.

Betanin Dose-Dependently Ameliorates Allergic Airway Inflammation by Attenuating Th2 Response and Upregulating cAMP-PKA-CREB Pathway in Asthmatic Mice

Allergic asthma is a refractory disease that affects hundreds of millions of people worldwide. Betanin is a natural plant-derived nutrient and possesses health-promoting properties. The effects of betanin on allergic asthma remain unknown. Herein, the effects and mechanisms of betanin on allergic asthma were explored in ovalbumin (OVA)-induced BALB/c mice. Betanin in doses of 0, 20, 60, and 180 mg/kg was applied. Peripheral inflammatory cells, IgE, pulmonary pathology, T cell subsets, cytokine levels, protein expressions of the cAMP-PKA-CREB/CREM pathway, and gut microbial profile were measured. The 60 and 180 mg/kg/day betanin doses significantly downregulated IgE, eotaxin, eosinophil infiltration, mucus hyperproduction, and Th2. A 180 mg/kg/day betanin dose also significantly reduced percentages of Th17, Tc17, and Tc2 and Th2- and Th17-signature cytokines and upregulated the cAMP-PKA-CREB pathway. Additionally, 20 mg/kg/day betanin altered the gut microbial profile. In conclusion, betanin dose-dependently alleviated allergic asthma and upregulated the cAMP-PKA-CREB pathway in mice. This study provides a novel nutritional strategy to treat allergic asthma.

Rosiglitazone ameliorated airway inflammation induced by cigarette smoke via inhibiting the M1 macrophage polarization by activating PPARγ and RXRα

BACKGROUND

Rosiglitazone, an exogenous ligand of PPARγ, plays an important anti-inflammatory role during the inflammation caused by cigarette smoke (CS). CS exposure induces pulmonary inflammation via activating macrophage polarization. However, the effects of rosiglitazone on macrophage polarization induced by CS are unclear.

METHODS

36 male Wistar rats were randomly divided into 3 groups: control, CS and ROSI. In the CS group, rats were passively exposed to cigarette smoke for consecutive 3 months. In the ROSI group, rats were treated with rosiglitazone (3 mg/kg/day, ip) during CS exposure period. Alveolar macrophages of rats were isolated and cultured with CSE. The slices of lung tissues were stained with hematoxylin and eosin. The histomorphology was observed to evaluate emphysema and the pulmonary function was detected. Cells in bronchoalveolar lavage fluid (BALF) were examined and the expression of cytokines TNF-α and IL-1β was detected by ELISA and qPCR. The alveolar macrophage polarization was evaluated by immunohistochemistry and flow cytometry assay in vivo and by qPCR in vitro. The protein level of PPARγ and RXRα was measured by Western blot.

RESULTS

CS exposure induced significant emphysema, diminished FEV0.2/FVC, elevated PEF, and higher level of total cells, neutrophils and cytokines (TNF-α and IL-1β) in BALF compared with control group, whereas rosiglitazone partly ameliorated above disorders. CS exposure activated M1 and M2 macrophage polarization in vivo and in vitro, whereas rosiglitazone inhibited CS induced M1 macrophage polarization and decreased the ratio of M1/M2. The effects of rosiglitazone on macrophage polarization were partly blocked after AMs treated with the antagonists of PPARγ and RXRα, and were synergistically enhanced by the agonist of RXRα. CS exposure decreased the expression of PPARγ and RXRα in lung tissues and AMs, and rosiglitazone partly reversed CS-mediated suppression of PPARγ and RXRα.

CONCLUSION

Rosiglitazone ameliorated the emphysema and inflammation in lung tissues induced by CS exposure via inhibiting the M1 macrophage polarization through activating PPARγ and RXRα.

MicroRNA-21 released from mast cells-derived extracellular vesicles drives asthma in mice by potentiating airway inflammation and oxidative stress

OBJECTIVE

Mast cells-derived extracellular vesicles (EVs) play vital roles in various physiological and pathophysiological conditions. However, the cargoes of mast cells-derived EVs in asthma have not been established. Here, we set to identify the role of microRNA-21 (miRNA-21) from mast cells-derived EVs in ozone- and lipopolysaccharide (LPS)-induced mouse airway epithelial cells (MIC-iCell-a006 cells) and asthmatic mice.

METHODS

After ozone or LPS treatment, MIC-iCell-a006 cells were subjected to a microarray analysis to screen differentially expressed miRNAs, and then co-cultured with EVs. miR-21 was silenced in cells, followed by CCK-8, scratch, and Transwell assays. Mice were challenged with ovalbumin, and antioxidant enzymes and inflammatory cell infiltration were assessed after EVs and miR-21 inhibitor treatments. The relation between miR-21 and DDAH1 was evaluated by Dual-luciferase assay, and changes in Wnt/β-catenin pathway related proteins were examined by western blot. Finally, the involvement of the DDAH1/Wnt/β-catenin axis in miR-21-mediated oxidative stress and inflammation was verified by rescue experiments.

RESULTS

miR-21 expression was upregulated in MIC-iCell-a006 cells induced by ozone or LPS. miR-21 was enriched in mast cells-derived EVs, and EVs increased miR-21 expression in MIC-iCell-a006 cells. miR-21 inhibitor increased cell activity and alleviated oxidative stress and inflammation. In asthmatic mice, miR-21 expression was increased, and EVs decreased antioxidant enzymes and increased inflammatory cells, whose effects were reversed by miR-21 knockdown. miR-21 targeted DDAH1 to mediate the Wnt/β-catenin signaling, and down-regulation of DDAH1 inhibited the action of miR-21 inhibitor.

CONCLUSION

The miR-21 secreted from mast cells-derived EVs promotes oxidative stress and inflammatory responses in asthmatic mice via the DDAH1/Wnt/β-catenin signaling axis.

Coronavirus infection: An immunologists' perspective

Coronavirus infections are frequent viral infections in several species. As soon as the severe acute respiratory syndrome (SARS) appeared in the early 2000s, most of the research focused on pulmonary disease. However, disorders in immune response and organ dysfunctions have been documented. Elderly individuals with comorbidities exhibit worse outcomes in all the coronavirus that cause SARS. Disease severity in SARS-CoV-2 infection is related to severe inflammation and tissue injury, and effective immune response against the virus is still under analysis. ACE2 receptor expression and polymorphism, age, gender and immune genetics are factors that also play an essential role in patients' clinical features and immune responses and have been partially discussed. The present report aims to review the physiopathology of SARS-CoV-2 infection and propose new research topics to understand the complex mechanisms of viral infection and viral clearance.