Non-IgE-reactive allergen peptides deteriorate the skin barrier in house dust mite-sensitized atopic dermatitis patients

Genome-based analysis for the identification of candidate genes associated with skin-photosensitization tolerance in sheep

In ruminant livestock, skin photosensitization, caused by the ingestion of toxic plants, is relatively common and affects animal production. In this study, genotyping data from the Illumina OvineSNP50 BeadChip from two Italian local sheep breeds (Leccese and Altamurana) were used to identify putative genomic regions associated with response to skin photosensitization. We identified four genomic regions harbouring several candidate genes related to dermatitis, immune response, and coat color, that could be potentially involved in modulating photosensitization in sheep. These findings enhance our understanding of the genetic mechanisms underlying skin photosensitization in sheep and provide valuable insights into livestock adaptation to local environmental pressure.

Advances of the exposome at individual levels and prevention in atopic dermatitis

Atopic dermatitis (AD), or eczema, is an inflammatory skin disease related to environmental factors. As a heterogeneous disease, it presents with complex phenotypes and endotypes. A variety of intrinsic and extrinsic factors can promote the development of AD. While there has been extensive discussion on environmental exposure at the population and community levels, discourse on exposome at individual levels in AD remains insufficient. For example, allergens, microorganisms, parasites, dietary factors, and psychological factors such as stress and anxiety play important roles in AD development. Microorganisms, in particular, exhibit altered composition and diversity on the skin of AD patients, influencing skin barrier integrity and immune responses. The impact of certain microorganisms, such as fungi and viruses, on AD has garnered increasing attention because of their important role in maintaining skin homeostasis. Dietary factors, including sugar intake and histamine-rich foods, may modulate AD risk and severity, although findings are controversial. Allergens, particularly house dust mite allergens, and aeroallergens, exacerbate AD symptoms by promoting inflammation and barrier dysfunction. Since AD is often the first step in the atopic march, its primary prevention measures are crucial. Some preventive measures involving microorganisms, diet, and moisturizers remain controversial. Effective preventive strategies necessitate a clear understanding of the complex mechanisms of AD, especially host-microbe-environment interactions. This review summarizes recent advances in understanding various risk and protective factors, as well as primary prevention measures for AD.

The novel house dust mite allergen Der p 39 exacerbates atopic dermatitis-like inflammation in mice by inducing skin barrier dysfunction

Background

House dust mite (HDM) allergens can induce or exacerbate allergic inflammation, including atopic dermatitis (AD). Substances that damage the epithelial barrier can trigger or worsen AD. The mechanism by which the novel HDM allergen Der p 39 induces allergic inflammation remains unclear. Our aim was to investigate the effects of Der p 39 on AD-like inflammation and associated mechanisms.

Methods

Dinitrochlorobenzene (DNCB) and Der p 39 were utilized to establish AD model mice. Inflammation severity was evaluated with physiological and morphological assays. The effects of Der p 39 on inflammatory cytokine release and skin barrier protein expression were examined in HaCaT cells (human epidermal keratinocytes). Mitogen-activated protein kinase (MAPK) activation was examined by western blots. MAPK inhibitors were employed to assess MAPK involvement in filaggrin expression.

Results

Der p 39 worsened allergic inflammation (tissue thickness) in murine ears pretreated with 1% DNCB. Compared to controls, Der p 39-sensitized tissues showed epidermal and dermal thickening with elevated numbers of mast cells and eosinophils in inflammatory lesions. Der p 39 increased transcription and production of pro-inflammatory interleukins (ILs), down-regulated expression of the skin barrier proteins filaggrin and loricrin, and upregulated phosphorylation of ERK, JNK and p38 in HaCaT cells. Inhibition of MAPK signaling rescued filaggrin expression in Der p 39-treated cells.

Conclusions

The HDM allergen Der p 39 enhances allergic inflammation and promotes MAPK pathway-mediated epidermal barrier dysfunction, suggesting that Der p 39 may possess pathogenic and clinically relevant immunomodulatory potential.

Omics in allergy and asthma

This review explores the transformative impact of omics technologies on allergy and asthma research in recent years, focusing on advancements in high-throughput technologies related to genomics and transcriptomics. In particular, the rapid spread of single-cell RNA sequencing has markedly advanced our understanding of the molecular pathology of allergic diseases. Furthermore, high-throughput genome sequencing has accelerated the discovery of monogenic disorders that were previously overlooked as ordinary intractable allergic diseases. We also introduce microbiomics, proteomics, lipidomics, and metabolomics, which are quickly growing areas of research interest, although many of their current findings remain inconclusive as solid evidence. By integrating these omics data, we will gain deeper insights into disease mechanisms, leading to the development of precision medicine approaches that promise to enhance treatment outcomes.

Stiffness-Dependent Lysyl Oxidase Regulation through Hypoxia-Inducing Factor 1 Drives Extracellular Matrix Modifications in Psoriasis

Psoriasis is a common chronic inflammatory skin disease characterized by a thickened epidermis with elongated rete ridges and massive immune cell infiltration. It is currently unclear what impact mechanoregulatory aspects may have on disease progression. Using multiphoton second harmonic generation microscopy, we found that the extracellular matrix was profoundly reorganized within psoriatic dermis. Collagen fibers were highly aligned and assembled into thick, long collagen bundles, whereas the overall fiber density was reduced. This was particularly pronounced within dermal papillae extending into the epidermis. Furthermore, the extracellular matrix-modifying enzyme lysyl oxidase was highly upregulated in the dermis of patients with psoriasis. In vitro experiments identified a previously unreported link between hypoxia-inducing factor 1 stabilization and lysyl oxidase protein regulation in mechanosensitive skin fibroblasts. Lysyl oxidase secretion and activity directly correlated with substrate stiffness and were independent of hypoxia and IL-17. Finally, single-cell RNA-sequencing analysis identified skin fibroblasts expressing high amounts of lysyl oxidase and confirmed elevated hypoxia-inducing factor 1 expression in psoriasis. Our findings suggest a potential yet undescribed mechanical aspect of psoriasis. Deregulated mechanical forces hence may be involved in initiating or maintaining of a positive feedback loop in fibroblasts and contribute to tissue stiffening and diminished skin elasticity in psoriasis, potentially exacerbating disease pathogenesis.

Skin Barrier in Atopic Dermatitis

A compromised permeability barrier is a hallmark of atopic dermatitis (AD). Localized to the outermost skin layer, the stratum corneum (SC) is critically dependent on terminal differentiation of epidermal keratinocytes, which transform into protein-rich corneocytes surrounded by extracellular lamellae of unique epidermal lipids, conferring permeability barrier function. These structures are disrupted in AD. A leaky barrier is prone to environmental insult, which in AD elicits type 2-dominant inflammation, in turn resulting in a vicious cycle further impairing the SC structure. Therapies directed at enforcing SC structure and anti-inflammatory strategies administered by topical and systemic route as well as UV therapy have differential effects on the permeability barrier. The expanding armamentarium of therapeutic modalities for AD treatment warrants optimization of their effects on permeability barrier function.