IL‐13, periostin and dipeptidyl‐peptidase‐4 reveal endotype‐phenotype associations in atopic dermatitis

Background: The heterogeneous (endo)phenotypes of atopic dermatitis (AD) require precision medicine. Currently, systemic therapy is recommended to patients with an Eczema Area and Severity Index (EASI) ≥ 16. Previous studies have demonstrated an improved treatment response to the anti‐interleukin (IL)‐13 antibody tralokinumab in AD subgroups with elevated levels of the IL‐13‐related biomarkers dipeptidyl‐peptidase (DPP)‐4 and periostin. Methods: Herein, 373 AD patients aged ≥12 years were stratified by IL‐13$^{high}$, periostin$^{high}$ and DPP‐4$^{high}$ endotypes using cross‐sectional data from the ProRaD cohort Bonn. “High” was defined as >80th quantile of 47 non‐atopic controls. We analyzed endotype‐phenotype associations using machine‐learning gradient boosting compared to logistic regression. Results: Atopic dermatitis severity and eosinophils correlated with IL‐13 and periostin levels. Correlations of IL‐13 with EASI were stronger in patients with increased (rs = 0.482) than with normal (rs = 0.342) periostin levels. We identified eosinophilia >6% and an EASI range of 5.5–17 dependent on the biomarker combination to be associated with increasing probabilities of biomarker$^{high}$ endotypes. Also patients with mild‐to‐low‐moderate severity (EASI < 16) featured increased biomarkers (IL‐13$^{high}$: 41%, periostin$^{high}$: 48.4%, DPP‐4$^{high}$: 22.3%). Herthoge sign (adjusted Odds Ratio (aOR) = 1.89, 95% Confidence Interval (CI) [1.14–3.14]) and maternal allergic rhinitis (aOR = 2.79–4.47) increased the probability of an IL‐13$^{high}$‐endotype, “dirty neck” (aOR = 2.83 [1.32–6.07]), orbital darkening (aOR = 2.43 [1.08–5.50]), keratosis pilaris (aOR = 2.21 [1.1–4.42]) and perleche (aOR = 3.44 [1.72–6.86]) of a DPP‐4$^{high}$‐endotype. Conclusions: A substantial proportion of patients with EASI < 16 featured high biomarker levels suggesting systemic impact of skin inflammation already below the current cut‐off for systemic therapy. Our findings facilitate the identification of patients with distinct endotypes potentially linked to response to IL‐13‐targeted therapy

Atopic dermatitis: Correlation of distinct risk factors with age of onset in adulthood compared to childhood

Background: Atopic dermatitis (AD) has long been regarded as a primarily pediatric disease. However, there is growing evidence for a high rate of adult-onset AD. We aimed to characterize factors associated with adult-onset versus childhood-onset AD and controls. Methods: We analyzed cross-sectional data of the CK-CARE-ProRaD cohorts Bonn, Augsburg, Davos, Zürich of 736 adult patients stratified by age of AD onset (childhood-onset <18 years: 76.4% (subsets: 0 to 2; ≥2 to 6; ≥7 to 11; ≥12 to 18); adult-onset ≥18 years: 23.6% (subsets: ≥18 to 40; ≥41 to 60; ≥61) and 167 controls (91 atopic, 76 non-atopic)). Results: We identified active smoking to be associated with adult-onset AD versus controls (adjusted Odds Ratio (aOR) = 5.54 [95% Confidence Interval: 1.06-29.01] vs. controls$^{non-atopic}$ , aOR = 4.03 [1.20-13.45] vs. controls$^{atopic}$ ). Conjunctivitis showed a negative association versus controls$^{atopic}$ (aOR = 0.36 [0.14-0.91]). Food allergy (aOR = 2.93 [1.44-5.96]), maternal food allergy (aOR = 9.43 [1.10-80.95]), palmar hyperlinearity (aOR = 2.11 [1.05-4.25]), and academic background (aOR = 2.14 [1.00-4.54]) increased the odds of childhood-onset AD versus controls$^{atopic}$. Shared AD-associated factors were maternal AD (4-34x), increased IgE (2-20x), atopic stigmata (2-3x) with varying effect sizes depending on AD onset and control group. Patients with adult-compared to childhood-onset had doubled odds of allergic rhinitis (aOR = 2.15 [1.12-4.13]), but reduced odds to feature multiple (3-4) atopic comorbidities (aOR = 0.34 [0.14-0.84]). Adult-onset AD, particularly onset ≥61 years, grouped mainly in clusters with low contributions of personal and familial atopy and high frequencies of physical inactivity, childhood-onset AD, particularly infant-onset, mainly in "high-atopic"-clusters. Conclusions: The identified associated factors suggest partly varying endo- and exogeneous mechanisms underlying adult-onset versus childhood-onset AD. Our findings might contribute to better assessment of the individual risk to develop AD throughout life and encourage prevention by non-smoking and physical activity as modifiable lifestyle factors

Combination of two epitope identification techniques enables the rational design of soy allergen Gly m 4 mutants

Detailed IgE-binding epitope analysis is a key requirement for the understanding and development of diagnostic and therapeutic agents to address food allergies. An IgE-specific linear peptide microarray with random phage peptide display for the high-resolution mapping of IgE-binding epitopes of the major soybean allergen Gly m 4, which is a homologue to the birch pollen allergen Bet v 1 is combined. Three epitopes are identified and mapped to a resolution of four key amino acids, allowing the rational design and the production of three Gly m 4 mutants with the aim to abolish or reduce the binding of epitope-specific IgE. In ELISA, the binding of the mutant allergens to polyclonal rabbit-anti Gly m 4 serum as well as IgE purified from Gly m 4-reactive soybean allergy patient sera is reduced by up to 63% compared to the wild-type allergen. Basophil stimulation experiments using RBL-SX38 cells loaded with patient IgE are showed a decreased stimulation from 25% for the wild-type Gly m 4 to 13% for one mutant. The presented approach demonstrates the feasibility of precise mapping of allergy-related IgE-binding epitopes, allowing the rational design of less allergenic mutants as potential therapeutic agent

Frontostriatal functional connectivity correlates with repetitive behaviour across autism spectrum disorder and obsessive-compulsive disorder

Background: Autism spectrum disorder (ASD) and obsessive-compulsive disorder (OCD) are neurodevelopmental disorders with considerable overlap in terms of their defining symptoms of compulsivity/repetitive behaviour. Little is known about the extent to which ASD and OCD have common versus distinct neural correlates of compulsivity. Previous research points to potentially common dysfunction in frontostriatal connectivity, but direct comparisons in one study are lacking. Here, we assessed frontostriatal resting-state functional connectivity in youth with ASD or OCD, and healthy controls. In addition, we applied a cross-disorder approach to examine whether repetitive behaviour across ASD and OCD has common neural substrates. Methods: A sample of 78 children and adolescents aged 8-16 years was used (ASD n = 24; OCD n = 25; healthy controls n = 29), originating from the multicentre study COMPULS. We tested whether diagnostic group, repetitive behaviour (measured with the Repetitive Behavior Scale-Revised) or their interaction was associated with resting-state functional connectivity of striatal seed regions. Results: No diagnosis-specific differences were detected. The cross-disorder analysis, on the other hand, showed that increased functional connectivity between the left nucleus accumbens (NAcc) and a cluster in the right premotor cortex/middle frontal gyrus was related to more severe symptoms of repetitive behaviour. Conclusions: We demonstrate the fruitfulness of applying a cross-disorder approach to investigate the neural underpinnings of compulsivity/repetitive behaviour, by revealing a shared alteration in functional connectivity in ASD and OCD. We argue that this alteration might reflect aberrant reward or motivational processing of the NAcc with excessive connectivity to the premotor cortex implementing learned action patterns

A systematic review on the quantitative relationship between structural and functional network connectivity strength in mammalian brains

The mammalian brain is composed of densely connected and interacting regions, which form structural and functional networks. An improved understanding of the structure-function relation is crucial to understand the structural underpinnings of brain function and brain plasticity after injury. It is currently unclear how functional connectivity strength relates to structural connectivity strength. We obtained an overview of recent papers that report on correspondences between quantitative functional and structural connectivity measures in the mammalian brain. We included network studies in which functional connectivity was measured with resting-state fMRI, and structural connectivity with either diffusion-weighted MRI or neuronal tract tracers. Twenty-seven of the 28 included studies showed a positive structure-function relationship. Large inter-study variations were found comparing functional connectivity strength with either quantitative diffusion-based (correlation coefficient (r) ranges: 0.18-0.82) or neuronal tracer-based structural connectivity measures (r = 0.24-0.74). Two functional datasets demonstrated lower structure-function correlations with neuronal tracer-based (r = 0.22 and r = 0.30) than with diffusion-based measures (r = 0.49 and r = 0.65). The robust positive quantitative structure-function relationship supports the hypothesis that structural connectivity provides the hardware from which functional connectivity emerges. However, methodological differences between the included studies complicate the comparison across studies, which emphasize the need for validation and standardization in brain structure-function studies