The role of autophagy in allergic inflammation: a new target for severe asthma.
ABSTRACT: Autophagy has been investigated for its involvement in inflammatory diseases, but its role in asthma has been little studied. This study aimed to explore the possible role of autophagy and its therapeutic potential in severe allergic asthma. BALB/c mice were sensitized with ovalbumin (OVA) on days 0 and 14, followed by primary OVA challenge on days 28-30. The mice received a secondary 1 or 2% OVA challenge on days 44-46. After the final OVA challenge, the mice were assessed for airway responsiveness (AHR), cell composition and cytokine levels in bronchoalveolar lavage fluid (BALF). LC3 expression in lung tissue was measured by western blot and immunofluorescence staining. Autophagosomes were detected by electron microscopy. 3-Methyladenine (3-MA) treatment and Atg5 knockdown were applied to investigate the potential role of autophagy in allergic asthma mice. AHR, inflammation in BALF and LC3 expression in lung tissue were significantly increased in the 2% OVA-challenged mice compared with the 1% OVA-challenged mice (P<0.05). In addition, eosinophils showed prominent formation of autophagosomes and increased LC3 expression compared with other inflammatory cells in BALF and lung tissue. After autophagy was inhibited by 3-MA and Atg5 shRNA treatment, AHR, eosinophilia, interleukin (IL)-5 levels in BALF and histological inflammatory findings were much improved. Finally, treatment with an anti-IL-5 antibody considerably reduced LC3 II expression in lung homogenates. Our findings suggest that autophagy is closely correlated with the severity of asthma through eosinophilic inflammation, and its modulation may provide novel therapeutic approaches for severe allergic asthma.
Project description:This study aimed to investigate the anti-allergic effects of Lactobacillus plantarum K37 (K37) on airway hyperresponsiveness (AHR) and systemic allergic responses in ovalbumin (OVA)-sensitized and -challenged BALB/c mice. Heat-inactivated K37 (105, 107, and 109 CFU/mouse, day) were orally administered to OVA-sensitized BALB/c mice to investigate their effects on AHR, immunoglobulin (Ig) and cytokine production. The results showed that K37 dose-dependently lowered the serum levels of IgE, OVA-specific IgE and OVA-specific IgG1, ameliorated AHR induced by methacholine and suppressed eosinophil infiltration in bronchoalveolar lavage fluid (BALF). The cytokine production in spleen cells culture and BALF showed that K37 drove the immune responses toward T-helper cell type 1 (Th1) responses, elevated levels of IL-2 and IFN-?, and reduced of IL-4, IL-5 and IL-13. K37 also improved cell infiltration in lung sections. Our results demonstrated that oral administration of K37 alleviated effectively the allergic responses in vivo. Thus, K37 can be a good source material and a promising candidate for prophylactic and therapeutic treatments of allergic diseases, like asthma.
Project description:Suhuang antitussive capsule (Suhuang), a traditional Chinese medication, is found effective in treating chronic cough and cough variant asthma (CVA). This study aimed to determine the possible effects and underlying mechanisms of Suhuang on chronic ovalbumin (OVA)-induced airway hyperresponsiveness (AHR), inflammation, and remodeling in mice. Mice were randomly assigned to six experimental groups: control, OVA model with or without Suhuang (low dose: 3.5 g/kg, middle dose: 7.0 g/kg, high dose: 14.0 g/kg), or dexamethasone (2.5 mg/kg). AHR, inflammatory cells, cytokines in bronchoalveolar lavage fluid (BALF), lung pathology, mucus production, and airway remodeling were examined. We found Suhuang treated at lower doses effectively inhibited OVA-induced AHR, airway inflammation, mucus production and collagen deposition around the airway. High dose of Suhuang reduced most of the inflammatory hallmarks while exerted inconsiderable effects on the number of macrophages in BALF and AHR. At all doses, Suhuang significantly reduced the levels of interlukin (IL) -13 and transforming growth factor (TGF)-?1, but had little effects on IL-4, IL-5, IL-17A and interferon (IFN)-?. Thus, Suhuang administration alleviates the pathological changes of chronic asthma likely through inhibition of IL-13 and TGF-?1. Suhuang might be a promising therapy for patients with allergic asthma in the future.
Project description:Allergic asthma is a lifelong airway condition that affects people of all ages. In recent decades, asthma prevalence continues to increase globally, with an estimated number of 250,000 annual deaths attributed to the disease. Although inhaled corticosteroids and ?-adrenergic receptor agonists are the primary therapeutic avenues that effectively reduce asthma symptoms, profound side effects may occur in patients with long-term treatments. Therefore, development of new therapeutic strategies is needed as alternative or supplement to current asthma treatments. Sesamin is a natural polyphenolic compound with strong anti-oxidative effects. Several studies have reported that sesamin is effective in preventing hypertension, thrombotic tendency, and neuroinflammation. However, it is still unknown whether sesamin can reduce asthma-induced allergic inflammation and airway hyperresponsiveness (AHR). Our study has revealed that sesamin exhibited significant anti-inflammatory effects in ovalbumin (OVA)-induced murine asthma model. We found that treatments with sesamin after OVA sensitization and challenge significantly decreased expression levels of interleukin-4 (IL-4), IL-5, IL-13, and serum IgE. The numbers of total inflammatory cells and eosinophils in BALF were also reduced in the sesamin-treated animals. Histological results demonstrated that sesamin attenuated OVA-induced eosinophil infiltration, airway goblet cell hyperplasia, mucus occlusion, and MUC5AC expression in the lung tissue. Mice administered with sesamin showed limited increases in AHR compared with mice receiving vehicle after OVA challenge. OVA increased phosphorylation levels of I?B-? and nuclear expression levels of NF-?B, both of which were reversed by sesamin treatments. These data indicate that sesamin is effective in treating allergic asthma responses induced by OVA in mice.
Project description:It is well-established that bacterial and viral infections have an exacerbating effect on allergic asthma, particularly aggravating respiratory symptoms, such as airway hyperresponsiveness (AHR). The mechanism by which these infections alter AHR is unclear, but some studies suggest that Toll-like receptors (TLRs) play a role. In this study, we investigated the impact of TLR3 and TLR4 ligands on AHR and airway inflammation in a model of pre-established allergic inflammation. Female BALB/c mice were sensitised and challenged intranasally (i.n.) with either PBS or ovalbumin (OVA) and subsequently i.n. challenged with poly (I:C) (TLR3) or LPS (TLR4) for four consecutive days. The response to methacholine was measured in vivo; cellular and inflammatory mediators were measured in blood, lung tissue and broncheoalveolar lavage fluid (BALF). OVA challenge resulted in an increase in AHR to methacholine, as well as increased airway eosinophilia and TH2 cytokine production. Subsequent challenge with TLR agonists resulted in a significant increase in AHR, but decreased TLR-specific cellular inflammation and production of immune mediators. Particularly evident was a decline in LPS-induced neutrophilia and neutrophil-associated cytokines following LPS and poly (I:C) treatment. The present data indicates that TLRs may play a pivotal role in AHR in response to microbial infection in allergic lung inflammation. These data also demonstrate that aggravated AHR occurs in the absence of an exacerbation in airway inflammation and that allergic inflammation impedes a subsequent inflammatory response to TLRs. These results may parallel clinical signs of microbial asthma exacerbation, including an extended duration of illness and increased respiratory symptoms.
Project description:Obesity is a known risk factor for allergic asthma. It has been recognized as a key player in the pathogenesis of several inflammatory disorders via activation of macrophages, which is also vital to the development of allergic asthma. We investigated the mechanism of obesity-related asthma and whether treating obesity through exercise or diet ameliorates the severity of asthma in the obesity-related asthma model. We generated diet-induced obesity (DIO) in C57BL/6 mice by high-fat-feeding and ovalbumin-induced asthma (lean-OVA or DIO-OVA). The DIO-OVA mice were then treated with tumor necrosis factor (TNF)-? neutralizing antibody as a TNF-? blockade or a Cl2MDP-containing liposome to induce an alveolar macrophage deficiency. To treat obesity, the DIO-OVA mice were under dietary restrictions or exercised. The pathophysiological and immunological responses were analyzed. Airway hyperresponsiveness (AHR), serum IgE and TNF-? levels in the lung tissue increased in the DIO-OVA mice compared to the lean-OVA mice. Both the TNF-? blockade and depletion of alveolar macrophages in the DIO-OVA mice decreased AHR compared to the DIO-OVA mice. Treating obesity by exercise or through dietary means also reduced pulmonary TNF-? levels and AHR in the DIO-OVA mice. These results suggest that restoring normal body weight is an appropriate strategy for reducing TNF-? levels, and controlling inflammation may help improve asthma severity and control in obesity-related asthma.
Project description:Asthma is a chronic inflammatory disease of airways mediated by T-helper 2 (Th2) cells involving complex signaling pathways. Although resveratrol has previously been shown to attenuate allergic asthma, the role of miRNA in this process has not been studied. We investigated the effect of resveratrol on ovalbumin-induced experimental allergic asthma in mice. To that end, BALB/c mice were immunized with ovalbumin (OVA) intraperitoneally followed by oral gavage of vehicle (OVA-veh) or resveratrol (100 mg/kg body) (OVA-res). On day 7, the experimental groups received intranasal challenge of OVA followed by 7 days of additional oral gavage of vehicle or resveratrol. At day 15, all mice were euthanized and bronchioalveolar fluid (BALF), serum and lung infiltrating cells were collected and analyzed. The data showed that resveratrol significantly reduced IL-5, IL-13, and TGF-? in the serum and BALF in mice with OVA-induced asthma. Also, we saw a decrease in CD3+CD4+, CD3+CD8+, and CD4+IL-4+ cells with increase in CD4+CD25+FOXP3+ cells in pulmonary inflammatory cell infiltrate in OVA-res group when compared to OVA-veh. miRNA expression arrays using lung infiltrating cells showed that resveratrol caused significant alterations in miRNA expression, specifically downregulating the expression of miR-34a. Additionally, miR-34a was found to target <i>FOXP3</i>, as evidenced by enhanced expression of <i>FOXP3</i> in the lung tissue. Also, transfection studies showed that miR-34a inhibitor upregulated <i>FOXP3</i> expression while miR-34a-mimic downregulated <i>FOXP3</i> expression. The current study suggests that resveratrol attenuates allergic asthma by downregulating miR-34a that induces increased expression of <i>FOXP3</i>, a master regulator of Treg development and functions.
Project description:Stressed or injured cells release ATP into the extracellular milieu via the pannexin1 (Panx1) channels, which is the basis of inflammation in a variety of conditions, including allergic lung inflammation. Although the role of Panx1 in mediating inflammation has been well established, the role of its mimetic peptide, 10Panx1, which inhibits ATP release from Panx1 channels, in allergic asthma remains understudied. The aim of this study was to evaluate the effects of using 10Panx1 to inhibit Panx1 channel in a murine model of ovalbumin (OVA)-induced asthma. We demonstrate that blockade of Panx1 significantly attenuated goblet cell hyperplasia and inflammatory cell infiltration into the lungs of OVA-sensitized mice. Inhibition of Panx1 also reduced the total and eosinophil cell numbers in the bronchoalveolar lavage fluid (BALF) and reduced expression of CCL11 and CCL2 in lung tissues from mice. Moreover, we detected lower levels of IL-5 and IL-13 in the culture supernatant of OVA-restimulated splenocytes from 10Panx1-treated mice. Collectively, our findings suggest that Panx1 inhibition of allergen-mediated lung inflammation has the potential to suppress allergic responses in asthma.
Project description:Asthma is a chronic respiratory condition, with airway hyperresponsiveness (AHR) and inflammation as hallmarks. The hypothesis that the substantially increased expression of arginase 1 in activated macrophages limits the availability of L-arginine for nitric oxide synthesis, and thus increases AHR in lungs of mice with experimentally induced allergic asthma was recently refuted by several studies. In the present study, we tested the hypothesis that, instead, a low circulating concentration of arginine aggravates AHR in the same murine asthma model. Female FVB F/A2 tg/tg transgenic mice, which overexpress rat arginase 1 in their enterocytes, exhibit a ~?50% decrease of their plasma L-arginine concentration.Adult female F/A2 tg/tg mice and their wild-type littermates (F/A2 wt/wt ) were sensitized and challenged with ovalbumin (OVA/OVA). Lung function was assessed with the flexiVent™ system. Adaptive changes in the expression of arginine-metabolizing or -transporting enzymes, chemokines and cytokines, and lung histology were quantified with qPCR, ELISA, and immunohistochemistry, respectively.Reduction of circulating L-arginine concentration significantly increased AHR in OVA/OVA-treated mice and, to a lesser extent, even in PBS/OVA-treated mice. The pulmonary inflammatory response in OVA/OVA-treated F/A2 tg/tg and F/A2 wt/wt mice was comparable. OVA/OVA-treated F/A2 tg/tg mice differed from similarly treated female mice, in which arginase 1 expression in lung macrophages was eliminated, by a complete absence of an adaptive increase in the expression of arginine-metabolizing or -transporting enzymes.A reduction of the circulating L-arginine concentration rather than the macrophage-mediated increase of arginine catabolism worsens AHR.
Project description:<h4>Background</h4>Adverse health effects of tobacco smoke arise partly from its influence on innate and adaptive immune responses, leading to impaired innate immunity and host defense. The impact of smoking on allergic asthma remains unclear, with various reports demonstrating that cigarette smoke enhances asthma development but can also suppress allergic airway inflammation. Based on our previous findings that immunosuppressive effects of smoking may be largely attributed to one of its main reactive electrophiles, acrolein, we explored the impact of acrolein exposure in a mouse model of ovalbumin (OVA)-induced allergic asthma.<h4>Methods</h4>C57BL/6 mice were sensitized to ovalbumin (OVA) by intraperitoneal injection with the adjuvant aluminum hydroxide on days 0 and 7, and challenged with aerosolized OVA on days 14-16. In some cases, mice were also exposed to 5 ppm acrolein vapor for 6 hrs/day on days 14-17. Lung tissues or brochoalveolar lavage fluids (BALF) were collected either 6 hrs after a single initial OVA challenge and/or acrolein exposure on day 14 or 48 hrs after the last OVA challenge, on day 18. Inflammatory cells and Th1/Th2 cytokine levels were measured in BALF, and lung tissue samples were collected for analysis of mucus and Th1/Th2 cytokine expression, determination of protein alkylation, cellular thiol status and transcription factor activity.<h4>Results</h4>Exposure to acrolein following OVA challenge of OVA-sensitized mice resulted in markedly attenuated allergic airway inflammation, demonstrated by decreased inflammatory cell infiltrates, mucus hyperplasia and Th2 cytokines. Acrolein exposure rapidly depleted lung tissue glutathione (GSH) levels, and induced activation of the Nrf2 pathway, indicated by accumulation of Nrf2, increased alkylation of Keap1, and induction of Nrf2-target genes such as HO-1. Additionally, analysis of inflammatory signaling pathways showed suppressed activation of NF-?B and marginally reduced activation of JNK in acrolein-exposed lungs, associated with increased carbonylation of RelA and JNK.<h4>Conclusion</h4>Acrolein inhalation suppresses Th2-driven allergic inflammation in sensitized animals, due to direct protein alkylation resulting in activation of Nrf2 and anti-inflammatory gene expression, and inhibition of NF-?B or JNK signaling. Our findings help explain the paradoxical anti-inflammatory effects of cigarette smoke exposure in allergic airways disease.
Project description:Matrix metalloproteinases (MMPs) modulate development, inflammation, and repair in lungs. Tissue inhibitors of MMPs (TIMPs) interact with MMPs, controlling the intensity and nature of the response to injury. Absence of MMP-9, -2, and -8 activities is associated with altered lung inflammation during allergic sensitization. To test the hypothesis that the absence of TIMP-1 enhances allergic lung inflammation, airway hyperreactivity (AHR), and lung remodeling in asthma, we studied TIMP-1 null (TIMP-1 KO) mice and their WT controls using an ovalbumin (OVA) asthma model. TIMP-1 KO mice, compared to WT controls, developed an asthma phenotype characterized by AHR, pronounced cellular lung infiltrates, greater reduction in lung compliance, enhanced Th2 cytokine mRNA and protein expression, and altered collagen lung content associated with enhanced MMP-9 activity. Our findings support the hypothesis that TIMP-1 plays a protective role by preventing AHR and modulating inflammation, remodeling, and cytokine expression in an animal model of asthma.