Deficiency of decorin induces expression of Foxp3 in CD4⁺CD25⁺ T cells in a murine model of allergic asthma

Plumbagin alleviates obesity-related asthma: Targeting inflammation, oxidative stress, and the AMPK pathway

BACKGROUND

Obesity-related asthma, a specific type of asthma, tends to have more severe symptoms and more frequent exacerbations, and it is insensitive to standard medications. Plumbagin (PLB) has many positive effects on human health. However, it remains unclear whether PLB protects against obesity-related asthma. The study investigated the effect of PLB on obesity-related asthma.

METHODS

Four-week-old male C57BL6/J mice were fed either standard-chow diet or high-fat diet (HFD). The mice were sensitized to 100 μg ovalbumin (OVA) once a week and intraperitoneally injected with 1 mg/kg PLB once daily from Week 10 to 11 and then challenged with 10 μg OVA twice a day on Week 12. The lung tissue and bronchoalveolar lavage fluid (BALF) were collected 48 h after the first OVA challenge.

RESULTS

HFD enhanced inflammatory cell infiltration within the airways and increased total inflammatory cell and eosinophil counts, levels of eosinophil-related inflammatory cytokines, including interleukin-4 (IL-4), IL-5, and eotaxin in BALF, and oxidative stress in the lung tissues of asthmatic mice. PLB reduced inflammatory cell infiltration in the airway walls, levels of eosinophil-related inflammatory cytokines in BALF, and oxidative stress in lung tissues of obese asthmatic mice. In addition, PLB restored HFD-induced decreases in adenosine monophosphate-activated protein kinase (AMPK) phosphorylation.

CONCLUSION

The study suggested that HFD exacerbated inflammation and oxidative stress, while PLB probably alleviated inflammation and oxidative stress and activated AMPK pathway to attenuate obesity-associated asthma. Thus, PLB likely had the potential to treat obesity-related asthma.

Peanut allergen induces more serious allergic reactions than other allergens involving MAPK signaling pathways

There is no universally accepted uniform research to classify the severity of allergic reactions triggered by different food allergens. We established a food allergy model based on repeated intragastric administrations of proteins from peanut, egg, milk, or soybean mixed with cholera toxin followed by oral food challenges with a high dose of the sensitizing proteins. Increased specific IgE, specific IgG1, allergic symptom scores, histamine, murine mast cell proteases-1, vascular leakage, Th2 cytokines, and mast cell infiltration in the lungs and intestine were found in the allergic groups via enzyme-linked immunosorbent assay, hematoxylin-eosin, and toluidine blue staining. Each sensitized group showed a decrease in body temperature and Th1 cytokines after oral food challenge. The increased levels of Th2 cytokines, IL-25, IL-33, and TSLP, and related asthma genes ARG1, DCN, LTB4R1 and NFKBIA as well as the activation of MAPK signaling pathways were also revealed by quantitative real-time PCR and western blotting. In terms of the severity of food allergies, peanut allergy was the most serious followed by egg and milk, and soybean allergy was the least severe. Compared to other allergic groups, asthma genes were regulated through the MAPK signaling pathways to produce related Th2 cytokines in peanut allergy; consequently, mice in the peanut group exhibited more severe allergic reactions. Comparison of the severity of food allergies is required for the development of milder prevention for severe food allergies.

The Role of Decorin in Autoimmune and Inflammatory Diseases

Decorin is an extracellular matrix protein that belongs to the family of small leucine-rich proteoglycans. As a matrix protein, the first discovered role of decorin is participating in collagen fibril formation. Many other functions of decorin in various biological processes have been subsequently identified. Decorin is involved in an extensive signaling network and can interact with other extracellular matrix components, growth factors, receptor tyrosine kinases, and various proteases. Decorin has been shown to be involved in wound repair, cell cycle, angiogenesis, tumor metastasis, and autophagy. Recent evidence indicates that it also plays a role in immune regulation and inflammatory diseases. This review summarizes the characteristics of decorin in immune and inflammatory diseases, including inflammatory bowel disease (IBD), Sjögren's syndrome (SS), chronic obstructive pulmonary disease (COPD), IgA nephropathy, rheumatoid arthritis (RA), spondyloarthritis (SpA), osteoarthritis, multiple sclerosis (MS), idiopathic inflammatory myopathies (IIM), and systemic sclerosis (SSc) and discusses the potential role in these disorders.

Agnuside mitigates OVA-LPS induced perturbed lung homeostasis via modulating inflammatory, autophagy, apoptosis-fibrosis response and myeloid lineages in mice model of allergic asthma

Attributes of agnuside, a nontoxic, iridoid glycoside have been advocated for inflammatory disorders. However, information on its efficacy in alleviating allergic asthma largely remain ambiguous and yet to be deciphered. Present study aimed to assess efficacy of agnuside in targeting vicious circle of oxi-inflammation, autophagy and fibrosis, together with investigating its underlying molecular mechanism during OVA-LPS induced allergic asthma. Results revealed that agnuside showed prophylactic effect in assuaging asthmatic lung architecture impairment (p ≤ 0.01) as indicated by suppression of inflammatory cell infiltration, congestion, fibrosis, airway remodeling and alveolar collapse in OVA-LPS sensitized group. Decreased expression level (p ≤ 0.05) of allergic inflammatory mediators such as IgE, Th1/Th2, IL-4/IFN-γ, IL-4/IL-10, chemokines, endopeptidases and TGF-β, Smad2/4, Caspase9/3, connexin 43/50 observed in agnuside treatments. Analysis of redox molecular signaling cascade and autophagic proteins revealed concurrent upregulation in p-NF-κB, p-PI3K, p-Akt, p-p38, p-Stat3 activation, GATA3, LC3B expression and reduction in Bcl2/Bax, Beclin1 and p62 expression in sensitized mice (p ≤ 0.05) which were intensely counteracted by administration of agnuside. Suppression in myeloid cells activation and augmentation (p ≤ 0.001) of Tregs established modulatory attribute of agnuside for innate and adaptive immune response during allergic asthma. Collectively, these outcomes confer prophylactic attribute of agnuside and signify it as promising strategy to thwart allergic asthma.

Asthma reduces glioma formation by T cell decorin-mediated inhibition of microglia

To elucidate the mechanisms underlying the reduced incidence of brain tumors in children with Neurofibromatosis type 1 (NF1) and asthma, we leverage Nf1 optic pathway glioma (Nf1^OPG) mice, human and mouse RNAseq data, and two different experimental asthma models. Following ovalbumin or house dust mite asthma induction at 4-6 weeks of age (WOA), Nf1^OPG mouse optic nerve volumes and proliferation are decreased at 12 and 24 WOA, indicating no tumor development. This inhibition is accompanied by reduced expression of the microglia-produced optic glioma mitogen, Ccl5. Human and murine T cell transcriptome analyses reveal that inhibition of microglia Ccl5 production results from increased T cell expression of decorin, which blocks Ccl4-mediated microglia Ccl5 expression through reduced microglia NFκB signaling. Decorin or NFκB inhibitor treatment of Nf1^OPG mice at 4-6 WOA inhibits tumor formation at 12 WOA, thus establishing a potential mechanistic etiology for the attenuated glioma incidence observed in children with asthma.

Communications via the Small Leucine-rich Proteoglycans: Molecular Specificity in Inflammation and Autoimmune Diseases

Inflammation is a highly regulated biological response of the immune system that is triggered by assaulting pathogens or endogenous alarmins. It is now well established that some soluble extracellular matrix constituents, such as small leucine-rich proteoglycans (SLRPs), can act as danger signals and trigger aseptic inflammation by interacting with innate immune receptors. SLRP inflammatory signaling cascade goes far beyond its canonical function. By choosing specific innate immune receptors, coreceptors, and adaptor molecules, SLRPs promote a switch between pro- and anti-inflammatory signaling, thereby determining disease resolution or chronification. Moreover, by orchestrating signaling through various receptors, SLRPs fine-tune inflammation and, despite their structural homology, regulate inflammatory processes in a molecule-specific manner. Hence, the overarching theme of this review is to highlight the molecular and functional specificity of biglycan-, decorin-, lumican-, and fibromodulin-mediated signaling in inflammatory and autoimmune diseases.

Proteoglycan neofunctions: regulation of inflammation and autophagy in cancer biology

Inflammation and autophagy have emerged as prominent issues in the context of proteoglycan signaling. In particular, two small, leucine-rich proteoglycans, biglycan and decorin, play pivotal roles in the regulation of these vital cellular pathways and, as such, are intrinsically involved in cancer initiation and progression. In this minireview, we will address novel functions of biglycan and decorin in inflammation and autophagy, and analyze new emerging signaling events triggered by these proteoglycans, which directly or indirectly modulate these processes. We will critically discuss the dual role of proteoglycan-driven inflammation and autophagy in tumor biology, and delineate the potential mechanisms through which soluble extracellular matrix constituents affect the microenvironment associated with inflammatory and neoplastic diseases.

Decorin interacting network: A comprehensive analysis of decorin-binding partners and their versatile functions

Decorin, a prototype small leucine-rich proteoglycan, regulates a vast array of cellular processes including collagen fibrillogenesis, wound repair, angiostasis, tumor growth, and autophagy. This functional versatility arises from a wide array of decorin/protein interactions also including interactions with its single glycosaminoglycan side chain. The decorin-binding partners encompass numerous categories ranging from extracellular matrix molecules to cell surface receptors to growth factors and enzymes. Despite the diversity of the decorin interacting network, two main roles emerge as prominent themes in decorin function: maintenance of cellular structure and outside-in signaling, culminating in anti-tumorigenic effects. Here we present contemporary knowledge regarding the decorin interacting network and discuss in detail the biological relevance of these pleiotropic interactions, some of which could be targeted by therapeutic interventions.