Asthma, obesity, and microbiota: A complex immunological interaction

Alteration of salivary Streptococcus is associated with statin therapy in older adults: a cohort study

Background

Salivary microbiome alterations are associated with chronic diseases, such as cardiovascular disease, diabetes, and dementia. These chronic diseases often coexist in older adults, leading to polypharmacy. This situation complicates the relationship between systemic diseases and salivary microbiome dysbiosis. Previous studies have demonstrated the association of the human gut microbiome with common prescription drug use, including polypharmacy. However, a comprehensive analysis of the salivary microbiome and prescription drugs is yet to be conducted in older adults. Therefore, in this study, we performed a multivariate analysis to investigate the relationship between salivary microbiomes and host variables, including prescribed drugs, cognitive function, and oral health, in Japanese older adults with different disease backgrounds.

Methods

We enrolled non-hospitalised 82 older adults aged ≥70 years from a Japanese village community, and collected metadata, including age, sex, body mass index, cognitive function, oral health, alcohol consumption, smoking, and common prescription drug information. We performed multivariate analyses and functional predictions on the salivary microbiome based on 16S ribosomal RNA gene amplicon sequencing, including the metadata as potential confounders.

Results

We observed a relationship between the human salivary microbiome and prescribed drug use in Japanese older adults with a heterogeneous background of comorbidities. The effects of several prescribed drugs, such as statins, proton pump inhibitors, and transporter/symporter inhibitors, on the salivary microbiome diversity were more prominent than those of host variables, including age, sex, and oral health. Notably, statin use was strongly correlated with a decrease in the Streptococcus abundance. Furthermore, statin intensity and obesity may be associated with altering the salivary microbiome, including functional predictions for vitamin biosynthesis and purine nucleotide degradation pathways in statin users.

Conclusion

Our multivariate analysis, adjusted for prescribed drug use and non-use, revealed the drug-specific alteration of salivary microbiome composition in Japanese older adults with comorbidities. To our knowledge, this study is the first to described the association of common prescription drug use with salivary microbiome alterations in older adults. Our findings indicated that prescribed drug use is a key factor in understanding the link between salivary microbiome changes and systemic diseases in older adults.

Glycolysis in asthma: Its role and potential as a diagnostic or therapeutic target

Asthma is a heterogeneous disease characterized by chronic airway inflammation and hyperresponsiveness. A number of immune cells are involved in asthma pathogenesis, such as eosinophils, mast cells, T lymphocytes and neutrophils, as well as airway epithelial cells. Glycolysis plays a crucial role in glucose metabolism, and serves as a bridge between metabolic and inflammatory dysfunction. Research has found that abnormal glycolytic metabolism in various immune cells may contribute to the pathogenesis of asthma by inducing dysregulation in congenital and adaptive immune responses. Therefore, the inhibition of glycolysis can be a viable approach to prevent airway inflammation in asthma. The present study reviews the relationship between glycolysis and inflammatory cells in different asthma subtypes, and its potential therapeutic significance.

Involucrasin B suppresses airway inflammation in obese asthma by inhibiting the TLR4-NF-κB-NLRP3 pathway

BACKGROUND

Obese asthma is an asthma phenotype that causes more severe lung inflammation and airway hyperresponsiveness than allergic asthma and it is resistant to conventional therapy. Involucrasin B (IB) is a dihydroflavonoid isolated from Shuteria involucrata (Wall.) Wight & Arn., a traditional "Dai" and "Wa" medicine was used in southern China to treat the "phlegm and wetness of sputum" (obesity disease) as well as lung inflammation. However, whether IB can ameliorate obese asthma remains unclear, and the underlying mechanisms and molecular expression in obese asthma specifically targeted by IB are still not fully understood.

METHODS

An in vivo C57BL/6 J mouse model of obese asthma was established using house dust mites (HDMs) and high-fat diet (HFD) as inducers to evaluate the therapeutic effect of IB. An in vitro cell culture of human THP-1 monocytic cell culture was used to investigate the effect of IB after the treatment with lipopolysaccharide (LPS) and palmitic acid (PA).

RESULTS

In vivo, we found that intervention with IB improved airway hyperresponsiveness and lung histopathology and significantly inhibited the secretion of relevant inflammatory factors, such as interleukin (IL)-1β, IL-17A, and IL-22 in bronchoalveolar lavage fluid, and total-IgE and HDM-IgE in serum compared with the model group (HFD+HDM). The findings indicate that IB could decrease the expression of granulocyte receptor 1 (Gr-1) and neutrophil extracellular traps (NETs) in lung tissue, as well as the expression of NLR family pyrin domain containing 3 (NLRP3) and inducible nitric oxide synthase in M1 macrophages (M1). IB also reduced the population of ILC3/Th17 cells, which are responsible for producing IL-17A, a crucial mediator of neutrophil-mediated inflammation, confirming that the therapeutic effect of IB in obesity-related asthma was related to neutrophils and M1 cells. In addition, IB regulated lipid metabolism and inhibited the production of macrophages in adipose tissue. The in vitro results revealed that IB inhibited the secretion of IL-1β, IL-18, and tumor necrosis factor-α (TNF-α) from THP-1 cells, and the expression of NLRP3-related protein in THP-1 cells compared with the model groups (LPS, PA, and LPS+PA), confirming that the action of IB involved the TLR4-NF-κB-NLRP3 pathway.

CONCLUSION

This study demonstrated the therapeutic effect of IB in obese asthma for the first time and further clarified its mechanistic pathway as the TLR4-NF-κB-NLRP3 pathway.

The Impact of High-Fructose Diet and Co-Sensitization to House Dust Mites and Ragweed Pollen on the Modulation of Airway Reactivity and Serum Biomarkers in Rats

The topic of ragweed pollen (RW) versus house dust mites (HDMs) has often been deliberated, but the increasing incidence of co-sensitization between them has been scarcely addressed. Utilizing Sprague Dawley rats, we explored the effects of co-sensitization with the combination of HDMs and RW pollen extracts in correlation with high-fructose diet (HFrD) by in vitro tracheal reactivity analysis in isolated organ bath and biological explorations. Our findings unveiled interrelated connections between allergic asthma, dyslipidemia, and HFrD-induced obesity, shedding light on their compounding role through inflammation. The increased CRP values and airway hyperresponsiveness to the methacholine challenge suggest a synergistic effect of obesity on amplifying the existing inflammation induced by asthma. One of the major outcomes is that the co-sensitization to HDMs and RW pollen led to the development of a severe allergic asthma phenotype in rats, especially in those with HFrD. Therefore, the co-sensitization to these allergens as well as the HFrD may play a crucial role in the modulation of systemic inflammation, obesity, and airway reactivity.

TRP channels associated with macrophages as targets for the treatment of obese asthma

Globally, obesity and asthma pose significant health challenges, with obesity being a key factor influencing asthma. Despite this, effective treatments for obese asthma, a distinct phenotype, remain elusive. Since the discovery of transient receptor potential (TRP) channels in 1969, their value as therapeutic targets for various diseases has been acknowledged. TRP channels, present in adipose tissue cells, influence fat cell heat production and the secretion of adipokines and cytokines, which are closely associated with asthma and obesity. This paper aims to investigate the mechanisms by which obesity exacerbates asthma-related inflammation and suggests that targeting TRP channels in adipose tissue could potentially suppress obese asthma and offer novel insights into its treatment.

Daqing formula ameliorated allergic asthma and airway dysbacteriosis in mice challenged with ovalbumin and ampicillin

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a chronic airway inflammatory disease that can lead to several complications caused by bacterial infections. However, recurrent attacks of the disease require long-term use of antibiotics, resulting in lung dysbiosis and poor outcomes. Daqing Formula (DQF) is a well-known herbal medicine in Pharmacopoeia of China, which is widely used for various stimuli-induced lower respiratory diseases, including asthma, bronchitis, and pneumonia. Thus, it has been demonstrated to be a plant-derived broad-spectrum antibiotic for treating and preventing various acute and chronic respiratory diseases.

AIM OF THE STUDY

This study evaluated the efficacy and possible mechanism of DQF on allergic asthma and airway dysbiosis.

METHODS AND MATERIALS

The mice were co-challenged with ovalbumin and ampicillin to induce allergic asthma combined with airway dysbacteriosis. The populations of lung microbiota were detected by using 16s DNA sequencing. The levels of asthmatic markers in BALF were detected by ELISA. The levels of Th1/Th2 cytokines in splenic CD4+ cells of mice were analyzed by flow cytometry. The expressions of the GSK-3β signaling pathway in the lung tissues of asthmatic mice and eosinophils were detected by western blotting assay. The inhibition of DQF on the production of pro-inflammatory cytokines in eosinophils of asthmatic mice.

RESULTS

The results showed that treatment with DQF at 200-800 mg/kg doses significantly reduced the frequency of nasal rubbing and lung inflammation as well as the number of total cells, eosinophils, and macrophages in bronchoalveolar lavage fluid. It decreased the relative abundances of Streptococcus, Cuoriavidus, and Moraxella, increased Akkermansia and Prevotella_6 in lung tissues of asthmatic mice, and inhibited the growth of Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and their resistant strains in vitro. Furthermore, DQF reduced the levels of eotaxin, TSLP, IL-4, IL-5, IL-25, and IL-33, but enhanced IFN-γ and IL-12 in BALF. It elevated the population of Th1 cells, inhibited eosinophil activation, and downregulated the expressions of p-GSK-3β, p-p65, nuclear β-catenin, and p-STAT3 in the lung tissues of asthmatic mice.

CONCLUSIONS

The results revealed that DQF reduced airway inflammation, ameliorated lung dysbiosis, shifted the Th1/Th2 balance, and inhibited eosinophil activation in asthmatic mice, indicating its potential for severe asthma treatment.

Differential Modulation of Mouse Intestinal Organoids with Fecal Luminal Factors from Obese, Allergic, Asthmatic Children

Asthma is a multifactorial condition that can be associated with obesity. The phenotypes of asthma in lean and obese patients are different, with proinflammatory signatures being further elevated in the latter. Both obesity and asthma are associated with alterations in intestinal barrier function and immunity, and with the composition of the intestinal microbiota and food consumption. In this study, we aimed to establish an organoid model to test the hypothesis that the intestinal content of lean and obese, allergic, asthmatic children differentially regulates epithelial intestinal gene expression. A model of mouse jejunum intestinal organoids was used. A group of healthy, normal-weight children was used as a control. The intestinal content of asthmatic obese children differentially induced the expression of inflammatory and mitochondrial response genes (Tnf-tumor necrosis factor, Cd14, Muc13-mucin 13, Tff2-Trefoil factor 2 and Tff3, Cldn1-claudin 1 and 5, Reg3g-regenerating family member 3 gamma, mt-Nd1-NADH dehydrogenase 1 and 6, and mt-Cyb-mitochondrial cytochrome b) via the RAGE-advanced glycosylation end product-specific receptor, NF-κB-nuclear factor kappa b and AKT kinase signal transduction pathways. Fecal homogenates from asthmatic normal-weight and obese children induce a differential phenotype in intestinal organoids, in which the presence of obesity plays a major role.

Obesity-Associated Non-T2 Mechanisms in Obese Asthmatic Individuals

Obesity and asthma are two common health issues that have shown increased prevalence in recent years and have become a significant socioeconomic burden worldwide. Obesity increases asthma incidence and severity. Obese asthmatic individuals often experience increased exacerbation rates, enhanced airway remodeling, and reduced response to standard corticosteroid therapy. Recent studies indicate that obesity-associated non-T2 factors such as mechanical stress, hyperinsulinemia, systemic inflammation, adipose tissue mediators, metabolic dysregulation, microbiome dysbiosis, and high-fat-diet are responsible for increased asthma symptoms and reduced therapeutic response in obese asthmatic individuals. This manuscript reviews the recent findings highlighting the role of obesity-associated factors that contribute to airway hyper-reactivity, airway inflammation and remodeling, and immune cell dysfunction, consequently contributing to worsening asthma symptoms. Furthermore, the review also discusses the possible future therapies that might play a role in reducing asthma symptoms by diminishing the impact of obesity-associated non-T2 factors.

Mendelian randomization analysis to analyze the genetic causality between different levels of obesity and different allergic diseases

BACKGROUND

The causal relationship between obesity and different allergic diseases remains controversial.

METHODS

The Two Sample MR package and Phenoscanner database were used to obtain and filter Genome-Wide Association Study (GWAS) data from the Open GWAS database. Mendelian randomization (MR) analysis was used to study the causal relationship between different levels of obesity and different allergic diseases. The data sets related to obesity and asthma were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened by the limma package. Cluster Profiler and GO plot packages were used for enrichment analysis to verify the results of MR analysis.

RESULTS

Two-sample MR analysis showed a causal relationship between obesity and childhood allergy (age < 16), allergic asthma and atopic dermatitis (P < 0.05). In addition, there was also a causal relationship between allergic asthma and obesity (P < 0.05), while there was no genetic causal relationship between obesity and allergic rhinitis, eczema, lactose intolerance and so on (P > 0.05). Subgroup analysis revealed a causal relationship between both class 1 and class 2 obesity and childhood allergy (age < 16) (P < 0.05). Obesity class 1 was associated with allergic asthma, while obesity class 3 was associated with atopic dermatitis (P < 0.05). Bioinformatics analysis shows that there were common DEGs between obesity and allergic asthma.

CONCLUSION

Obesity is a risk factor for childhood allergy (age < 16), allergic asthma and atopic dermatitis, while allergic asthma is also a risk factor for obesity. Class 1 and class 2 obesity are both causally associated with childhood allergy (age < 16). In addition, there is a causal relationship between milder obesity and allergic asthma, while heavier obesity is causally related to atopic dermatitis.

Whole Blood Expression Levels of Long Noncoding RNAs: HOTAIRM1, GAS5, MZF1-AS1, and OIP5-AS1 as Biomarkers in Adolescents with Obesity-Related Asthma

Asthma is a heterogeneous entity encompassing distinct endotypes and varying phenotypes, characterized by common clinical manifestations, such as shortness of breath, wheezing, and variable airflow obstruction. Two major asthma endotypes based on molecular patterns are described: type 2 endotype (allergic-asthma) and T2 low endotype (obesity-related asthma). Long noncoding RNAs (lncRNAs) are transcripts of more than 200 nucleotides in length, currently involved in many diverse biological functions, such as chromatin remodeling, gene transcription, protein transport, and microRNA processing. Despite the efforts to accurately classify and discriminate all the asthma endotypes and phenotypes, if long noncoding RNAs could play a role as biomarkers in allergic asthmatic and adolescent obesity-related asthma, adolescents remain unknown. To compare expression levels of lncRNAs: HOTAIRM1, OIP5-AS1, MZF1-AS1, and GAS5 from whole blood of Healthy Adolescents (HA), Obese adolescents (O), allergic asthmatic adolescents (AA) and Obesity-related asthma adolescents (OA). We measured and compared expression levels from the whole blood of the groups mentioned above through RT-q-PCR. We found differentially expressed levels of these lncRNAs between the groups of interest. In addition, we found a discriminative value of previously mentioned lncRNAs between studied groups. Finally, we generated an interaction network through bioinformatics. Expression levels of OIP5-AS1, MZF1-AS1, HOTAIRM1, and GAS5 in whole blood from the healthy adolescent population, obese adolescents, allergic asthma adolescents, and obesity-related asthma adolescents are differently expressed. Moreover, these lncRNAs could act as molecular biomarkers that help to discriminate between all studied groups, probably through molecular mechanisms with several genes and miRNAs implicated.