Shedding light on corticosteroid-resistant type 2-high severe asthma

Biomarkers in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition. The pathogenesis involves genetic, environmental, and immunological factors as well as a barrier dysfunction of the epidermis. Biomarkers may play a significant role in diagnosis, severity assessment, and treatment monitoring of AD. They are categorizable into diagnostic and prognostic as well as severity and stratification biomarkers, offering the potential for a more personalized treatment approach. Although there have been tremendous therapeutic advancements with interleukin (IL) antagonists and Janus kinase (JAK) inhibitors, the domain of biomarkers still requires further research to clarify their place in the diagnosis and prognosis of AD to unravel a better scientific basis for personalized medical care for patients with AD. This article reviews the various biomarkers in relation to the different AD phenotypes and endotypes.

DMOG protects against murine IL-33-induced pulmonary type 2 inflammation through HIF-1 pathway in innate lymphoid cells

One of the traditional methods of treating allergy is to avoid the allergen, protocol that has long been used in high altitude clinics. It has been hypothesized that the therapeutic effect of high altitude on allergy is due to allergen avoidance, exposure to sunlight and reduced stress. However, the contribution of environmental elements like low oxygen pressure and hypoxia remains underexplored. In this study, we examined the role of hypoxia in the development of type 2 lung inflammation. Mice were administered with papain or recombinant IL-33 intra-nasally to induce type 2 lung inflammation. Some of them were treated additionally with the prolyl hydroxylase (PHD) inhibitor DMOG, which mimics hypoxia. DMOG treatment exhibited an inhibitory effect on the lung inflammation induced by papain or IL-33, operating in a manner independent of T and B cells. The anti-inflammatory effect of DMOG was accompanied by a downregulation of IL-5 and IL-13 in innate lymphoid cells (ILCs), which was abolished in HIF-1α deficient mice. Collectively, our findings suggest that DMOG's modulatory effect on IL-5 and IL-13 operates through the HIF-1 pathway, resulting in a reduction in type 2 lung inflammation. These findings underscore the role of the PHD-HIF pathway in IL-5 and IL-13 expression in lung ILCs and pharmacological inhibition of PHD might be a novel therapeutic candidate for type 2 lung inflammation.

The ketone body β-hydroxybutyrate mitigates ILC2-driven airway inflammation by regulating mast cell function

Ketone bodies are increasingly understood to have regulatory effects on immune cell function, with β-hydroxybutyrate (BHB) exerting a predominantly anti-inflammatory response. Dietary strategies to increase endogenous ketone body availability such as the ketogenic diet (KD) have recently been shown to alleviate inflammation of the respiratory tract. However, the role of BHB has not been addressed. Here, we observe that BHB suppresses group 2 innate lymphoid cell (ILC2)-mediated airway inflammation. Central to this are mast cells, which support ILC2 proliferation through interleukin-2 (IL-2). Suppression of the mast cell/IL-2 axis by BHB attenuates ILC2 proliferation and the ensuing type 2 cytokine response and immunopathology. Mechanistically, BHB directly inhibits mast cell function in part through GPR109A activation. Similar effects are achieved with either the KD or 1,3-butanediol. Our data reveal the protective role of BHB in ILC2-driven airway inflammation, which underscores the potential therapeutic value of ketone body supplementation for the management of asthma.

Circulating microRNA-15b-5p as a biomarker for asthma-COPD overlap

BACKGROUND

It remains unclear how to characterize different subtypes of asthma and chronic obstructive pulmonary disease (COPD). We previously described serum periostin and chitinase-3-like protein 1 (YKL-40) as useful markers for asthma-COPD overlap (ACO). MicroRNAs (miRNAs) are now recognized as markers for identifying the pathophysiological features in several diseases. This study aimed to identify circulating miRNAs that could discriminate patients with ACO from patients with asthma or COPD.

METHODS

This study included two independent cohorts. First, we screened 84 miRNAs for expression levels in patients with ACO (n = 6) or asthma (n = 6) using a quantitative real-time PCR array. The miRNAs showing at least a 2-fold difference in the discovery phase were analyzed in 30 patients each with asthma, COPD, or ACO in the replication phase. The diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Nine miRNAs were identified in the discovery phase. Five of these miRNAs (miR-148a-3p, miR-15b-5p, miR-223-3p, miR-23a-3p, and miR-26b-5p) had lower levels in ACO patients and could discriminate between ACO patients and patients with either asthma or COPD. miR-15b-5p was the most accurate miRNA for the discrimination of patients with ACO (AUROC, 0.71). Moreover, the combined assessment of miR-15b-5p, serum periostin, and YKL-40 (AUROC, 0.80) improved diagnostic accuracy for ACO compared with the combined model of periostin and YKL-40 (AUROC, 0.69).

CONCLUSIONS

Circulating miR-15b-5p is a potential marker for identifying patients with ACO. By elucidating the molecular pathways controlled by miRNAs, we may better understand the pathophysiology of ACO.

Biologics or immunotherapeutics for asthma?

Asthma is now recognised as a heterogenous inflammatory disease of the lung based on cellular infiltrates and transcriptional profiles of blood and airway cells. Four distinct subgroups have been defined, eosinophilic (T2), neutrophilic (T1), mixed eosinophilic/neutrophilic and paucigranulocytic. Patients can also be stratified at a molecular level into T2-high, T2-low and/or T1 based on their gene signatures. Current treatments for asthma have been centred on administration of steroids and/or bronchodilators for the relief of bronchoconstriction and inflammation. These treatments are not always effective and often have limited efficacy during exacerbations. Eosinophil expansion and homing to tissues, bronchoconstriction, IgE production and mucus hypersecretion (hallmark features of asthma) are regulated by the type 2 cytokines IL-4, IL-5 and IL-13, the latter of which can induce the expression of the eosinophil chemotactic factors CCL11 and CCL24. A number of new generation biologics (monoclonal antibodies) targeting pathways regulated by the T2 cytokines IL-5 and IL-4/13 (IL-4 receptor alpha) have yielded effective therapies for eosinophil induced exacerbations of severe asthma. Despite these advances, difficulties still remain in treating all exacerbations, and this may reflect the contribution of other inflammatory cells such as neutrophils to pathogenesis. This review describes the effectiveness of targeting T2 pathways, emerging approaches and identifies the potential next steps for therapeutic intervention.