Skin barrier-related molecules and pathophysiology of asthma

Association between psoriasis and asthma: a systematic review and bidirectional meta-analysis

BACKGROUND

The risk of asthma in patients with psoriasis has been identified in previous studies, but the bidirectional association between the two has not been fully explored.

METHODS

We thoroughly searched PubMed, Embase, and the Cochrane Library to find relevant observational studies published from the inception of these databases to October 2023. All the risk and bias assessments were analyzed by STATA 16.0. Where the heterogeneity was less than 50%, the fixed effect model was utilized. While where the level of heterogeneity was more than 50%, the random effect model was applied. Moreover, to identify publication bias, a visual funnel chart, and Egger's test were applied.

RESULTS

A total of 12,396,911 participants from 16 studies, published between 2011 and 2023 were included in this meta-analysis. We found that psoriasis patients had a higher risk of developing asthma (OR = 1.48, 95%CI 1.28-1.68). Meanwhile, asthma patients also had a higher overall risk of developing psoriasis (OR = 1.33, 95%CI 1.23-1.44). In the subgroup analysis, we found that the type of study, age, and severity of the psoriasis were significant factors in the survey of asthma risk in psoriasis patients.

CONCLUSIONS

In the present systematic review and meta-analysis, we found a bidirectional association between psoriasis and asthma with significantly increased risk. As a result, clinicians should make patients aware of the connection between the two, particularly adolescents or patients with moderate to severe psoriasis who need to be informed about the rising likelihood of developing asthma.

TRIAL REGISTRATION

Registration number CRD42023390111 .

Understanding the key issues in the treatment of uncontrolled persistent asthma with type 2 inflammation

Asthma is a complex respiratory disease that varies in severity and response to treatment. Several asthma phenotypes with unique clinical and inflammatory characteristics have been identified. Endotypes, based on distinct molecular profiles, help to further elucidate the heterogeneity within asthma. Type 2 inflammation, involving both the innate (type 2 innate lymphoid cell) and adaptive (T-helper type 2 cells) immune systems, underpins the complex pathophysiology of chronic inflammation in asthma, as well as the presence of comorbid disease (e.g. chronic rhinosinusitis with nasal polyps, allergic rhinitis and atopic dermatitis). Type 2 inflammation is characterised by upregulation of the type 2 cytokines interleukin (IL)-4, IL-5 and IL-13, IgE-mediated release of immune mediators and dysfunction of epithelial or epidermal barriers. Targeting these key proximal type 2 cytokines has shown efficacy in recent studies adopting a personalised approach to treatment using targeted biologics. Elevated levels of biomarkers downstream of type 2 cytokines, including fractional exhaled nitric oxide, serum IgE and blood and sputum eosinophils, have been linked to mechanisms involved in type 2 inflammation. They have the potential to aid diagnosis, and to predict and monitor response to treatment. The objective of this review is to summarise the current understanding of the biology of type 2 inflammation in asthma, examine its influence on type 2 inflammatory comorbidities, and discuss how type 2 inflammatory biomarkers can be harnessed to further personalise treatments in the age of biologic medicines.

Intradermal Delivery of Antigens Enhances Specific IgG and Diminishes IgE Production: Potential Use for Vaccination and Allergy Immunotherapy

Skin is protected by a tough but flexible multilayered barrier and is a front line for immune responses against invading particles. For many years now, skin has been a tissue where certain vaccines are injected for the prevention of infectious disease, however, the detailed mechanisms of the skin immune response are not yet well understood. Using thin and small injection needles, we carefully injected OVA into a restricted region of mouse skin, i.e., intradermal (ID), and examined the antibody response in comparison with subcutaneous (SC) injection or epicutaneous patch administration of OVA. Epicutaneous patches induced a high IgE response against OVA, but IgG production was low. High IgG production was induced by both ID and SC injection, moreover, ID injection induced higher IgG production without any adjutants. Furthermore, OVA-specific IgE production was diminished by ID injection. We found that ID injection could efficiently stimulate skin resident DCs, drive Th1-biased conditions and diminish IgE production. The ID injection response was regulated by Langerin+ dermal DCs, because OVA was taken up mainly by these cells and, after transiently deleting them, the IgE response was no longer diminished and IgG1 production was enhanced. We also tested whether ID injection might be an effective allergy treatment by attempting to inhibit ongoing IgE production in mice with experimentally induced high serum IgE levels. Multiple ID injections of OVA were shown to prevent elevation of serum OVA-specific IgE after repeated allergen challenge. In contrast, SC OVA injection could only transiently inhibit the OVA-specific IgE production. These findings indicated that ID injection results in higher induction of antigen-specific IgG, and thus may be useful for vaccine delivery with little or no adjuvant components. Moreover, the observed diminishment of IgE and induction of Th1-biased immune responses suggest that ID may be a useful injection route for allergy immunotherapy.

IL-25 and IL-33 Contribute to Development of Eosinophilic Airway Inflammation in Epicutaneously Antigen-Sensitized Mice

BACKGROUND

IL-25, IL-33 and TSLP are produced predominantly by epithelial cells and are known to induce Th2-type cytokines. Th2-type cytokines are involved not only in host defense against nematodes, but also in the development of Th2-type allergic diseases. TSLP was reported to be crucial for development of allergic airway inflammation in mice after inhalation of allergens to which they had been sensitized epicutaneously (EC) beforehand. However, the roles of IL-25 and IL-33 in the setting remain unclear.

METHODS

Mice deficient in IL-25 and IL-33 were sensitized EC with ovalbumin (OVA) and then challenged intranasally with OVA. Airway inflammation, the number of inflammatory cells in bronchoalveolar lavage fluids (BALFs) and airway hyperresponsiveness (AHR) in the mice were determined, respectively, by histological analysis, with a hemocytometer, and by using plethysmograph chambers with a ventilator. Expression of mRNA in the skin and lungs was determined by quantitative PCR, while the BALF levels of myeloperoxidase (MPO) and eosinophil peroxidase (EPO) and the serum levels of IgE were determined by ELISA.

RESULTS

Normal OVA-specific Th2- and Th17-cell responses of lymph nodes and spleens were observed in IL-25-deficient (IL-25-/-) and IL-33-/- mice after EC sensitization with OVA. Nevertheless, the number of eosinophils, but not neutrophils, in the BALFs, and the levels of Th2 cytokines, but not Th17 cytokines, in the lungs were significantly decreased in the IL-25-/- and IL-33-/- mice pre-sensitized EC with OVA, followed by inhalation of OVA, whereas their levels of AHR and OVA-specific serum IgE were normal.

CONCLUSIONS

Both IL-25 and IL-33 are critical for induction of Th2-type cytokine-mediated allergic airway eosinophilia, but not Th17-type cytokine-mediated airway neutrophilia, at the local sites of lungs in the challenge phase of mice sensitized EC with OVA. They do not affect OVA-specific T-cell induction in the sensitization phase.

FLG P478S polymorphisms and environmental risk factors for the atopic march in Taiwanese children: a prospective cohort study

BACKGROUND

Little is known about the role of genetic and environmental modifiers in atopic march.

OBJECTIVE

To investigate the effects of filaggrin (FLG) P478S polymorphisms and environmental factors on the risk of asthma in a cohort of children with atopic dermatitis (AD).

METHODS

In 2010, 3,246 children from Childhood Environment and Allergic Diseases Cohort Study cohort were recruited. There were 485 children with AD who were invited for further clinical evaluation. Environmental exposures and skin prick tests for allergens were collected at 3 years of age and the development of asthma was determined at 6 years. Multivariate logistic regressions were performed to estimate the association between genetic and environmental factors and the development asthma in children with AD.

RESULTS

Of 397 children with AD who completed the follow-up, 97 developed asthma. After controlling for potential confounders, only mite sensitizations (odds ratio 1.89, 95% confidence interval 1.10-3.25) and the FLG TT genotype (odds ratio 2.26, 95% confidence interval 1.33-3.84) were significantly associated with the development of asthma in children with AD. Mite sensitizations and FLG variants had a synergistic effect on the development of asthma. When children with FLG variants were exposed to mite, the risk for asthma was compounded compared with those with FLG variants without mite exposure (odds ratio 3.58, 95% confidence interval 1.81-7.08).

CONCLUSION

Mite sensitization and the FLG TT genotype couldt be associated with the development of atopic march.