Breaking the steroid barrier: Emerging biomarkers and targeted therapies for type 2-low asthma

Diagnosis and Treatment Options for T2-Low Asthma.

Background: Type 2 (T2)-low asthma can be severe and corticosteroid-resistant. Airway epithelial cells play a pivotal role in the development of asthma, and mitochondria dysfunction is involved in the pathogenesis of asthma. However, the role of epithelial mitochondria dysfunction in T2-low asthma remains unknown.Methods: Differentially expressed genes (DEGs) were identified using gene expression omnibus (GEO) dataset GSE4302, which is originated from airway epithelial brushings from T2-high (n = 22) and T2-low asthma patients (n = 20). Gene set enrichment analysis (GSEA) was implemented to analyze the potential biological pathway involved between T2-low and T2-high asthma. T2-low asthma related genes were identified using weighted gene co-expression network analysis (WGCNA). The mitochondria-related genes (Mito-RGs) were referred to the Molecular Signatures Database (MSigDB). T2-low asthma related mitochondria (T2-low-Mito) DEGs were obtained by intersecting the DEGs, T2-low asthma related genes, and Mito-RGs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) was performed to further explore the potential function of the T2-low-Mito DEGs. In addition, the hub genes were further identified by protein-protein interaction (PPI), and the expressions of hub genes were verified in another GEO dataset GSE67472 and bronchial brushings from patients recruited at Tongji Hospital.Results: Six hundred and ninety-two DEGs, including 107 downregulated genes and 585 upregulated genes were identified in airway epithelial brushings from T2-high and T2-low asthma patients included in GSE4302 dataset. GSEA showed that mitochondrial ATP synthesis coupled electron transport is involved in T2-low asthma. Nine hundred and four T2-low asthma related genes were identified using WGCNA. Twenty-two T2-low-Mito DEGs were obtained by intersecting the DEGs, T2-low asthma and Mito-RGs. The GO enrichment analysis of the T2-low-Mito DEGs showed significant enrichment of mitochondrial respiratory chain complex assembly, and respiratory electron transport chain. PPI network was constructed using 22 T2-low-Mito DEGs, and five hub genes, ATP5G1, UQCR10, NDUFA3, TIMM10, and NDUFAB1, were identified. Moreover, the expression of these hub genes was validated in another GEO dataset, and our cohort of asthma patients.Conclusion: This study suggests that mitochondria dysfunction contributes to T2-low asthma.

Anti-aminoacyl-tRNA synthetase-interacting multifunctional protein-1 antibody improves airway inflammation in mice with house dust mite induced asthma

Asthma is a heterogeneous and complex condition characterized by chronic airway inflammation, which may be clinically stratified into three main phenotypes: type 2 (T2) low, T2-high allergic, and T2-high non-allergic asthma. This real-world study investigated whether phenotyping patients with asthma using non-invasive parameters could be feasible to characterize the T2-low and T2-high asthma phenotypes in clinical practice. This cross-sectional observational study involved asthmatic outpatients (n = 503) referring to the Severe Asthma Centre of the San Luigi Gonzaga University Hospital. Participants were stratified according to the patterns of T2 inflammation and atopic sensitization. Among outpatients, 98 (19.5%) patients had T2-low asthma, 127 (25.2%) T2-high non-allergic, and 278 (55.3%) had T2-high allergic phenotype. In comparison to T2-low, allergic patients were younger (OR 0.945, p < 0.001) and thinner (OR 0.913, p < 0.001), had lower smoke exposure (OR 0.975, p < 0.001) and RV/TLC% (OR 0.950, p < 0.001), higher prevalence of asthma severity grade 5 (OR 2.236, p < 0.05), more frequent rhinitis (OR 3.491, p < 0.001) and chronic rhinosinusitis with (OR 2.650, p < 0.001) or without (OR 1.919, p < 0.05) nasal polyps, but less common arterial hypertension (OR 0.331, p < 0.001). T2-high non-allergic patients had intermediate characteristics. Non-invasive phenotyping of asthmatic patients is possible in clinical practice. Identifying characteristics in the three main asthma phenotypes could pave the way for further investigations on useful biomarkers for precision medicine.

PurposeWe evaluated the role of serum amyloid A1 (SAA1) in the pathogenesis of airway inflammation according to the phenotype of asthma.MethodsOne hundred twenty-two asthmatic patients and 60 healthy control subjects (HCs) were enrolled to measure SAA1 levels. The production of SAA1 from airway epithelial cells (AECs) and its effects on macrophages and neutrophils were investigated in vitro and in vivo.ResultsThe SAA1 levels were significantly higher in sera of asthmatic patients than in those of HCs (P = 0.014); among asthmatics, patients with neutrophilic asthma (NA) showed significantly higher SAA1 levels than those with non-NA (P < 0.001). In vitro, polyinosinic:polycytidylic acid (Poly I-C) treatment markedly enhanced the production of SAA1 from AECs, which was further augmented by neutrophils; SAA1 could induce the production of interleukin (IL)-6, IL-8, and S100 calcium-binding protein A9 from AECs. Additionally, SAA1 activated neutrophils and macrophages isolated from peripheral blood of asthmatics, releasing neutrophil extracellular traps (NETs) and secreting proinflammatory cytokines presenting M1 phenotype, respectively. In ovalbumin-induced asthma mice, Poly I-C treatment significantly increased SAA1 levels as well as IL-17A/interferon-gamma/IL-33 levels in bronchoalveolar lavage fluid (BALF), leading to airway hyperresponsiveness and inflammation. The highest levels of SAA1 and neutrophilia were noted in the BALF and sera of the NA mouse model, followed by the mixed granulocytic asthma (MA) model. Especially, SAA1 induced IL-17/retinoic acid receptor-related orphan receptor γt expression from activated CD4+ T lymphocytes in asthmatic mice.ConclusionsThe results show that SAA1 could induce neutrophilic airway inflammation by activating neutrophils along with NET formation, M1 macrophages, and Th2/Th17 predominant cells, contributing to the phenotype of NA or MA.

T2-low asthma represents between 30-40% of severe asthma patients. It is less well defined compared to the allergic and eosinophilic asthma (T2-high asthma). There are no specific biomarkers for T2-low asthma but is often connected with the smoking, air pollution and obesity. Most of the patients have late onset asthma with more symptoms that are induced by exercise and cold exposure with frequent infective exacerbations and bronchiectasis. The responce to inhaled steroid treatment is poor, so the available therapeutic options and the targeted therapies effective in both T2-high and T2-low asthma like new anti-TSLP monoclonal antibody tezepelumab are discussed. Ongoing trials with sophisticated transcriptomic and proteomic characterisations of different T2-low asthma patients should provide us tools to better characterise these patients and choose the precise therapeutic approaches.

The NLRP3 inflammasome and NF-κB signaling pathways play crucial roles in orchestrating inflammation and immune defense.​ This review explores the intricate relationship between these pathways and epigenetic regulation, a field of growing importance in understanding immune responses. Epigenetic modifications, including DNA methylation, histone modifications, and non-coding RNAs (ncRNAs), significantly influence the activity of genes involved in these pathways, thereby modulating inflammatory responses. The review provides a comprehensive overview of current research on how epigenetic mechanisms interact with and regulate the NLRP3 inflammasome and NF-κB signaling pathways. It delves into advanced epigenetic concepts such as RNA modifications and 3D genome organization, and their impact on immune regulation. Furthermore, the implications of these findings for developing novel therapeutic strategies targeting epigenetic regulators in inflammatory diseases are discussed. By synthesizing recent advancements in this rapidly evolving field, this review underscores the critical role of epigenetic regulation in immune signaling and highlights the potential for epigenetic-based therapies in treating a wide range of inflammatory conditions, including autoimmune disorders and cancer.

Asthma, a common chronic inflammatory condition in the airways, significantly impacts individuals across all age groups and poses a substantial global health burden. Despite the availability of conventional treatments, a considerable proportion of asthmatic patients continue to experience uncontrolled asthma symptoms. This review focuses on neutrophilic asthma (NA), a challenging endotype characterized by lower lung function, a higher frequency of symptom exacerbations, and a poorer response to standard therapies. NA is typically diagnosed by an increase presence of airway neutrophils, as identified by sputum profile analysis. However, this method is not always available in resource-limited settings. Therefore, NA remains a public health concern that is still under-researched and under-diagnosed. Immune cell activation and their extracellular traps (ETs) could initiate the inflammatory signaling pathways, resulting in airway damage in asthma. These ETs released significant quantities of extracellular DNA, a process governed by the cytokines interleukin (IL)-8 and tumor necrosis factor-alpha. As a result, several investigations have identified these molecules as established biomarkers and explored therapies desinged to modulate neutrophil ETs (NETs), monocyte ETs (MoETs), and M1 macrophage ETs (M1ETs). Recent findings indicate that C-C motif chemokine ligand 4 like 2, calcium-binding protein A9, serum amyloid A1, and IL-1β promote NET formation, whereas monocyte chemoattractant protein-1 and soluble regulation of tumorigenicity 2 are essential components of MoETs and M1ETs. Therefore, these biomarkers are emerging as predictors for NETs, MoETs, and M1ETs. This review aims to discuss the pathophysiology, diagnostic criteria, and treatment options for NA, emphasizing the role of NETs, MoETs, and M1ETs in exacerbating airway inflammation.

News Beyond Our Pages

Asthma is primarily divided into two categories: type 2 (T2-high) and non-type 2 (T2-low). A relationship between asthma severity and vitamin D deficiency has been identified, but its impact on each asthma endotype remains unknown. We clinically examined the influence of vitamin D on patients with T2-high (n = 60) or T2-low asthma (n = 36) compared with controls (n = 40). Serum 25(OH)D levels, inflammatory cytokines and spirometry were measured. Mouse models were then used to further analyze the effects of vitamin D on both asthmatic endotypes. BALB/c mice were fed with vitamin D-deficient (LVD), -sufficient (NVD), or -supplemented diets (HVD) throughout lactation and offspring followed the same diet after weaning. Offspring were sensitized/challenged with ovalbumin (OVA) to establish "T2-high" asthma or OVA combined with ozone exposure (OVA + ozone) to induce "T2-low" asthma. Spirometry and serum, bronchoalveolar lavage fluid (BALF), and lung tissues were analyzed. Serum 25(OH)D levels were decreased in asthmatic patients compared with controls. Patients with vitamin D deficiency (Lo) had varying degrees of elevation of the pro-inflammatory cytokines IL-5, IL-6, and IL-17A, decreased expression of the anti-inflammatory cytokine IL-10, and altered forced expiratory volume in the first second as a percentage of predicted value (FEV1%pred) in both asthmatic endotypes. Vitamin D status had a stronger correlation with FEV1%pred in T2-low asthma than T2-high asthma, and 25(OH)D level was only positively linked to maximal mid-expiratory flow as a percentage of predicted value (MMEF%pred) in the T2-low group. Inflammation, hyperresponsiveness, and airway resistance (RL) was increased in both asthma models compared with controls while vitamin D deficiency further increased airway inflammation and airway obstruction. These findings were particularly prominent in T2-low asthma. The potential function and mechanisms of vitamin D and both asthma endotypes should be studied individually, and further analysis of the potential signaling pathways involved with vitamin D on T2-low asthma is warranted.

<b>Rationale:</b> There is a limited number of biomarkers to identify different phenotypes in childhood asthma, most reflecting type 2-inflammation. It is largely unknown whether such phenotyping can distinguish disease persistency and trajectories. <b>Method:</b> We included 338 children from the COPSAC₂₀₀₀ at-risk mother-child cohort. Asthma was diagnosed continuously during the whole follow-up period. Specific airway resistance (sRaw) was measured at every visit from age 3. T2-high vs. T2-low asthma was defined at age 7 as asthma with vs. without aeroallergen sensitization (≥ 0.35 kU_A/L) and/or fractional exhaled nitric oxide ≥ 20 ppb and/or blood eosinophil count ≥ 0.5 x 10⁹/L. Differences in lung function trajectories and persistent asthma by age 18 was analysed using linear mixed models and odds-ratio. <b>Results:</b> At age 7, 50 children had asthma including 26 children with T2-high and 24 with T2-low asthma. Of children with T2-high asthma, 12 (46.2 %) had persistent asthma as compared to 4 (16.7 %) with T2-low; OR=4.29 [1.14–16.1]; p=0.031. For T2-high vs. T2-low asthma, the median age of onset was 3.6 and 1.8 respectively (p=0.004) and mean duration of asthma was 9.91 vs. 5.86 years respectively (p=0.07). sRaw was 18 % higher through childhood in children with T2-high compared to T2-low asthma, Figure 1. <b>Conclusion:</b> The T2-high pediatric asthma phenotype has higher persistency and worse long-term lung function compared to T2-low.

It remains unclear whether phenotyping of type 2-high (T2-high) asthma can distinguish clinical characteristics and lung function trajectories in childhood. To explore differences between T2-high and T2-low asthma from birth to age 18 years. We included 47 children with asthma and 165 as a control group from the Copenhagen Prospective Studies on Asthma in Childhood2000 mother-child cohort. T2-high and T2-low asthma was defined at age 7 by sensitization to aeroallergens, elevated eosinophilic blood count, and/or elevated fractional nitric oxide. Lung function measurements included whole-body plethysmography, spirometry, exercise test, cold air provocation, and methacholine challenge. Differences in lung function trajectories and traits were analyzed using linear mixed models, Wilcoxon rank-sum test, Fisher's exact test, and Quasi-Poisson regression. At age 7 years, 47 had asthma (26 T2-high, 21 T2-low). By age 18, 12 (46.2%) with T2-high had persistent asthma whereas 2 (9.2%) with T2-low; OR 8.14 [1.57-42.34]. Specific airway resistance (sRaw) was 12.5% higher through childhood in children with T2-high asthma (estimate 0.53 [0.06; 1.01]); lung function was more reversible (OR 3.37 [1.03-11.00] for spirometry and OR 2.60 [1.17; 5.75] for sRaw), and they had increased airway hyperresponsiveness (AHR) to methacholine (as shown by 41% lower dose required to cause a 20% drop in lung function (estimate -0.70 [-1.18; -0.23])). There was no significant difference in exacerbation rate and other lung function measurements. Childhood T2-high asthma differs from T2-low asthma in terms of onset, duration, airway resistance, and airway responsiveness.

The Inhibitory Role of Hydrogen Sulfide in Airway Hyperresponsiveness and Inflammation in a Mouse Model of Asthma

Amyloid plaques, mainly composed of abnormally aggregated amyloid β-protein (Aβ) in the brain parenchyma, and neurofibrillary tangles (NFTs), consisting of hyperphosphorylated tau protein aggregates in neurons, are two pathological hallmarks of Alzheimer's disease (AD). Aβ fibrils and tau aggregates in the brain are closely associated with neuroinflammation and synapse loss, characterized by activated microglia and dystrophic neurites. Genome-wide genetic association studies revealed important roles of innate immune cells in the pathogenesis of late-onset AD by recognizing a dozen genetic risk loci that modulate innate immune activities. Furthermore, microglia, brain resident innate immune cells, have been increasingly recognized to play key, opposing roles in AD pathogenesis by either eliminating toxic Aβ aggregates and enhancing neuronal plasticity or producing proinflammatory cytokines, reactive oxygen species, and synaptotoxicity. Aggregated Aβ binds to toll-like receptor 4 (TLR4) and activates microglia, resulting in increased phagocytosis and cytokine production. Complement components are associated with amyloid plaques and NFTs. Aggregated Aβ can activate complement, leading to synapse pruning and loss by microglial phagocytosis. Systemic inflammation can activate microglial TLR4, NLRP3 inflammasome, and complement in the brain, leading to neuroinflammation, Aβ accumulation, synapse loss and neurodegeneration. The host immune response has been shown to function through complex crosstalk between the TLR, complement and inflammasome signaling pathways. Accordingly, targeting the molecular mechanisms underlying the TLR-complement-NLRP3 inflammasome signaling pathways can be a preventive and therapeutic approach for AD.

IntroductionSepsis-associated acute kidney injury (SA-AKI) is a highly lethal condition with a rapid onset, and effective treatments are lacking because the molecular pathogenesis remains unclear. Tubular epithelial cells (TECs) have increasingly been recognized as driving forces in the progression of kidney diseases, partly through the release of extracellular vesicles (EVs) carrying proinflammatory cargos. However, the role of TEC-derived EVs on neutrophil extracellular traps (NETs) formation, which is an established feature of sepsis, and SA-AKI remains unclear.MethodsEVs isolated from phosphate buffer saline (PBS)/lipopolysaccharide (LPS)-treated TECs were injected intravenously into C57BL/6J wild type mice to determine whether TECs-derived EVs can directly induce NETs formation and kidney injury. Proteomics and single-cell RNA sequencing analysis were used to screen the key molecules that mediate the effects of TECs-derived EVs. EVs secretion from TECs and serum amyloid A1 (SAA1) expression in TECs were specifically inhibited via adeno-associated virus (AAVs). Finally, the association between SAA1 level in plasma EVs and clinical features of septic patients was determined.ResultsThis study demonstrated that EVs secreted from LPS-stimulated TECs exacerbated AKI by promoting NETs formation. Specifically blocking EVs secretion from TECs via AAVs reduced NETs formation and alleviated LPS-induced AKI. Bioinformatics analysis suggested that LPS increased SAA1 expression in TECs, and then released extracellularly through EVs. Further mechanistic studies revealed that SAA1 packaged in TECs-derived EVs was responsible for NETs formation and AKI via activation of the TLR4/p38 MAPK signaling pathway in neutrophils. Specifically inhibiting SAA1 upregulation in TECs via AAVs also reduced NETs formation and alleviated LPS-induced AKI. Interestingly, modulating EVs release from TECs or SAA1 expression in TECs also alleviated remote lung injury induced by LPS, indicated that TECs-derived EVs may participate in kidney‒lung crosstalk during sepsis. Furthermore, plasma TECs-derived EVs proportion and SAA1 expression in plasma EVs may be promising prognostic indexes for SA-AKI patients.DiscussionHere, we explored a new mode of TECs-neutrophils crosstalk mediated by EVs during SA-AKI, and strategies to modify TECs-derived EVs and the cargo SAA1 could be a new avenue for developing therapeutics against SA-AKI.