Dupilumab-associated ocular surface disease is characterized by a shift from Th2/Th17 toward Th1/Th17 inflammation

BACKGROUND

Dupilumab is used for the treatment of atopic dermatitis (AD). Approximately one third of AD patients develop a dupilumab-associated ocular surface disease (DAOSD), of which the pathomechanism is poorly understood. This study aimed at investigating inflammatory markers in tear fluids of patients on dupilumab therapy.

METHODS

Tear fluids were collected from AD patients with DAOSD (ADwDAOSD), AD patients without DAOSD (ADw/oDAOSD), and non-AD patients before and during dupilumab therapy, and analyzed using a specialized proteomic approach quantifying inflammatory markers. The ocular surface microbiome was determined by next generation sequencing technology.

RESULTS

Upon dupilumab therapy, an upregulation of 31 inflammatory markers was observed in DAOSD tear fluids compared to baseline in AD patients. While IL-12B was upregulated in both ADwDAOSD and ADw/oDAOSD groups, the pattern of inflammatory markers significantly differed between groups and over time. In the ADwDAOSD group, a shift from a mixed Th2/Th17 pattern at baseline toward a Th1/Th17 profile under dupilumab was observed. Furthermore, an upregulation of remodeling and fibrosis markers was seen in DAOSD. Semantic map and hierarchical cluster analyses of baseline marker expression revealed four clusters distinguishing between AD and non-AD as well as ADwDAOSD and ADw/oDAOSD patient groups. In a pilot study, dupilumab therapy was associated with a decrease in richness of the ocular surface microbiome.

CONCLUSIONS

DAOSD is characterized by a Th1/Th17 cytokine profile and an upregulation of markers known to promote remodeling and fibrosis. The expression pattern of inflammatory markers in tear fluids at baseline might serve as a prognostic factor for DAOSD.

The Role of Regulatory T Cells in Allergic Diseases: Collegium Internationale Allergologicum (CIA) Update 2024

BACKGROUND

Allergy represents a major health problem of increasing prevalence worldwide with a high socioeconomic impact. Our knowledge on the molecular mechanisms underlying allergic diseases and their treatments has significantly improved over the last years. The generation of allergen-specific regulatory T cells (Tregs) is crucial in the induction of healthy immune responses to allergens, preventing the development and worsening of allergic diseases.

SUMMARY

In the last decades, intensive research has focused on the study of the molecular mechanisms involved in Treg development and Treg-mediated suppression. These mechanisms are essential for the induction of sustained tolerance by allergen-specific immunotherapy (AIT) after treatment discontinuation. Compelling experimental evidence demonstrated altered suppressive capacity of Tregs in patients suffering from allergic rhinitis, allergic asthma, food allergy, or atopic dermatitis, as well as the restoration of their numbers and functionality after successful AIT.

KEY MESSAGE

The better understanding of the molecular mechanisms involved in Treg generation during allergen tolerance induction might well contribute to the development of novel strategies for the prevention and treatment of allergic diseases.

Dictamnine Ameliorates DNFB-Induced Atopic Dermatitis Like Skin Lesions in Mice by Inhibiting M1 Macrophage Polarization and Promoting Autophagy

Autophagy and M1 macrophage polarization play important roles in the regulation of inflammation in atopic dermatitis (AD). Dictamnine is one of the main ingredients in Cortex Dictamni, a widely used traditional Chinese medicine for the treatment of dermatitis. In the present study, we investigated the anti-inflammatory effects of dictamnine on AD like skin lesions and M1 macrophage polarization. A 2,4-dinitrofluorobenzene (DNFB) triggered AD like skin lesions models in mice was established to identify the ameliorative effects of dictamnine on AD in vivo. In addition, an M1 macrophage polarization model was co-stimulated by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) using phorbol myristate acetate (PMA) differentiated THP-1 cells, to investigate the effect of dictamnine on promoting autophagy and inhibiting inflammatory factor release. Dictamnine suppressed DNFB-induced skin inflammation by inhibiting M1 macrophage polarization, up-regulating the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3) expression, and promoting macrophage autophagy at inflammatory sites. Dictamnine also could reduce the release of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1), and interleukin-8 (IL-8), and down-regulate the mRNA expression of these genes in LPS-IFN-γ triggered M1 polarized macrophages. Dictamnine ameliorates AD like skin lesions by inhibiting M1 macrophage polarization and promoting autophagy. Hence, dictamnine is expected to be a potential therapeutic candidate for AD.

Binding, Neutralization and Internalization of the Interleukin-13 Antibody, Lebrikizumab

INTRODUCTION

IL-13 is the primary upregulated cytokine in atopic dermatitis (AD) skin and is the pathogenic mediator driving AD pathophysiology. Lebrikizumab, tralokinumab and cendakimab are therapeutic monoclonal antibodies (mAb) that target IL-13.

METHODS

We undertook studies to compare in vitro binding affinities and cell-based functional activities of lebrikizumab, tralokinumab and cendakimab.

RESULTS

Lebrikizumab bound IL-13 with higher affinity (as determined using surface plasma resonance) and slower off-rate. It was more potent in neutralizing IL-13-induced effects in STAT6 reporter and primary dermal fibroblast periostin secretion assays than either tralokinumab or cendakimab. Live imaging confocal microscopy was employed to determine the mAb effects on IL-13 internalization into cells via the decoy receptor IL-13Rα2, using A375 and HaCaT cells. The results showed that only the IL-13/lebrikizumab complex was internalized and co-localized with lysosomes, whereas IL-13/tralokinumab or IL-13/cendakimab complexes did not internalize.

CONCLUSION

Lebrikizumab is a potent, neutralizing high-affinity antibody with a slow disassociation rate from IL-13. Additionally, lebrikizumab does not interfere with IL-13 clearance. Lebrikizumab has a different mode of action to both tralokinumab and cendakimab, possibly contributing to the clinical efficacy observed by lebrikizumab in Ph2b/3 AD studies.

Increased Expression of Toll-Like Receptor (TLR) 2 and TLR6 on Peripheral Blood Monocytes by Induction of Staphylococcal Enterotoxin B During Exacerbation of Atopic Dermatitis Patients

Background

Atopic dermatitis (AD) is a chronic and recurrent inflammatory skin disease that can be triggered by various precipitating factors, including colonization by Staphylococcus aureus (S. aureus). The toll-like receptor (TLR), which belongs to the family of pattern recognition receptors (PRR), can recognize components of S. aureus, such as staphylococcal enterotoxin B (SEB). This receptor is known to be expressed on monocytes. However, the understanding of the role of SEB in the pathogenesis of AD through the TLR pathway, especially TLR2 and TLR6, is not widely known.

Purpose

To investigate the expression of TLR2 and TLR6 on peripheral blood monocytes induced by SEB during AD exacerbations.

Patients and Methods

Twenty AD patients and 20 healthy subjects as a control group were selected. A 5 mL blood sample from each subject was taken for monocyte culture, which was induced by SEB for three days, and the outcomes were assessed by flow cytometry to evaluate TLR2 and TLR6 expression.

Results

The expression of TLR2 on peripheral blood monocytes in AD patients was increased compared to healthy controls (p = 0.000), but not for the expression of TLR6 (p = 0.304). In the AD group, TLR2 and TLR6 expression on peripheral blood monocytes after being induced by SEB was significantly increased compared to before induction (p = 0.025 and p = 0.023, respectively), but not in the control group (p = 0.737 and p = 0.100, respectively).

Conclusion

There is significantly increased expression of TLR2 and TLR6 on peripheral blood monocytes induced by SEB during exacerbation in AD patients.

The intestinal microbiome and the role of probiotics/prebiotics in the therapeutic approach of atopic dermatitis: A review

Atopic dermatitis (AD) is the most common chronic inflammatory skin condition, characterized by multiple recurrent eczematous lesions and intense itchiness. It is a multifactorial skin disorder involving an association between genetic and environmental factors that lead to a defect of the epithelial barrier in conjunction with immunological dysregulation. Over the last decade, there has been an increasing understanding of the role of the human microbiota in preserving skin integrity and that a shift in the homeostasis of these microorganisms may lead to dysbiosis and disease. Diversity in the intestinal microbiome and its role in the etiopathogenesis of AD has been described and has become of great interest. In this report, we have reviewed the importance of the gut microbiome and the possible mechanism in the pathogenesis of AD as well as the therapeutic impact of probiotics and prebiotics

Autophagy and Skin Diseases

Autophagy is a highly conserved lysosomal degradation system that involves the creation of autophagosomes, which eventually fuse with lysosomes and breakdown misfolded proteins and damaged organelles with their enzymes. Autophagy is widely known for its function in cellular homeostasis under physiological and pathological settings. Defects in autophagy have been implicated in the pathophysiology of a variety of human diseases. The new line of evidence suggests that autophagy is inextricably linked to skin disorders. This review summarizes the principles behind autophagy and highlights current findings of autophagy's role in skin disorders and strategies for therapeutic modulation.

Mimics of Dermatitis

Dermatitis is a common condition frequently encountered by dermatologists. The diagnosis of dermatitis can be challenging because this condition is often multifactorial, and many skin diseases that can mimic dermatitis should be considered in the differential diagnosis. It is important to recognize and be familiar with these conditions because some of them can represent signs of systemic disease or malignancies and misdiagnosis can lead to mismanagement and adverse outcomes for the patient.

Position statement on the role of nurses in therapeutic patient education in atopic dermatitis

In chronic skin diseases such as atopic dermatitis (AD), therapeutic failure due to poor patient adherence to treatment is commonly reported. Therapeutic patient education (TPE) is an approach to improve self-management and adherence. Several studies demonstrated that TPE programmes have positive effects on disease management resulting in decreased disease severity and improved quality of life in AD patients. Various healthcare professionals (dermatologists, nurses, psychologists, dieticians) have been involved. TPE performed by trained dermatology nurses are highly efficient and improve various health-related outcomes. The aim of this position paper is to analyse the aims, modalities and efficacy of TPE in AD, to identify specific roles of dermatology nurses, to assess qualification requirements, and to propose practical recommendations. Potential activities of nurses in ongoing and future TPE programmes for AD patients will be discussed.

Evidence for Lysosomal Dysfunction within the Epidermis in Psoriasis and Atopic Dermatitis

Atopic dermatitis and psoriasis are frequent chronic inflammatory skin diseases. Autophagy plays a substantial role in the homeostasis of an organism. Loss or impairment of autophagy is associated with multiple diseases. To investigate the possibility that autophagy plays a role in atopic dermatitis and psoriasis, we investigated the levels of key ATG proteins in human skin specimens as well as in primary human epidermal keratinocytes exposed to inflammatory stimuli in vitro. Although TNF-α facilitated the induction of autophagy in an initial phase, it reduced the levels and enzymatic activities of lysosomal cathepsins in later time periods, resulting in autophagy inhibition. Therefore, TNF-α appears to play a dual role in the regulation of autophagy. The relevance of these in vitro findings was supported by the observation that the protein levels of cathepsins D and L are decreased in both psoriasis and atopic dermatitis skin specimens. Taken together, this study suggests that TNF-α blocks autophagy in keratinocytes after long-term exposure, a mechanism that may contribute to the chronicity of inflammatory diseases of the skin and, perhaps, of other organs.

Eosinophils in skin diseases

Eosinophil infiltration is a common finding in a broad spectrum of skin diseases, despite the fact that the skin is devoid of eosinophils under physiologic conditions. Although cutaneous eosinophilia is reactive, cytokine-mediated in most cases, diseases with an intrinsic mutation-mediated clonal expansion of eosinophils can also manifest on the skin. As eosinophils are involved in host defense, regulate immune responses, generate pruritus, induce remodeling and fibrosis, and can cause tissue damage, they have the capacity to actively contribute to the pathogenesis of diseases. Recent research provided deeper insights in the mechanisms, e.g., bacterial and viral clearance, blister formation, recruitment of cytotoxic T cells, and generation of pruritus, by which eosinophils might come into action. This review aims at providing an overview on the clinical presentations of eosinophil-associated dermatoses and the current understanding of their pathogenic role in these diseases. Further, we discuss the effects of therapies targeting eosinophils.

Topical therapy of atopic dermatitis with a focus on pimecrolimus

Atopic dermatitis (AD) is a chronic and relapsing, inflammatory skin disease characterized by impaired skin barrier function and immune system dysregulation that results in dryness, skin microbiome dysbiosis and intense pruritus. It is highly heterogeneous, and its management is demanding. Patients with AD are at greater risk of comorbidities such as attention-deficit hyperactivity disorder as well as other atopic diseases. Early-onset AD cases typically improve or resolve in late childhood; however, it is proposed that the prevalence of persistent or adult-onset AD is higher than previously thought. Basic therapy consists of emollient application and trigger avoidance, and when insufficient, topical corticosteroids (TCS) are the first-line treatment. However, corticophobia/steroid aversion and TCS side-effects, particularly on sensitive skin areas, lead to low compliance and insufficient disease control. Several long- and short-term randomized controlled and daily practice studies have demonstrated that topical calcineurin inhibitors, such as pimecrolimus, have similar anti-inflammatory effects to low-to-medium strength TCS, reduce pruritus and improve the quality of life of patients. In addition, pimecrolimus does not cause skin atrophy, is steroid-sparing and has a good safety profile, with no evidence for an increased risk of malignancies or skin infections. In general, pimecrolimus cream is well-accepted and well-tolerated, encouraging patient adherence and leading to its use by many physicians as a preferred therapy for children and sensitive skin areas.

Impact of Atopic Dermatitis and Chronic Hand Eczema on Quality of Life Compared With Other Chronic Diseases

: The aim of this study was to conduct 3 literature reviews to examine the impact of atopic dermatitis (AD) and chronic hand eczema (CHE) on health-related quality of life (HRQoL) compared with other chronic conditions by comparing reported utility scores of 4 commonly used generic HRQoL instruments. A systematic search was performed using PubMed, ScienceDirect, MEDLINE, EMBASE, Health Technology Assessment database, and ScHARRHUD. Inclusion criteria included, but were not limited to, patients of any age, studies from any location, publications reporting utility data based on EuroQoL 5 dimensions, the EuroQoL 5-dimension Visual Analog Scale, the Short-Form Health Survey, and the Short-Form 6 Dimensions in the English language. Inclusion criteria were met by 16 articles for AD, 25 articles for chronic conditions, and 9 articles for CHE. The findings of this review highlight that the disutility and loss in HRQoL of patients with AD and CHE are similar to or higher than other chronic conditions, such as cancer or hepatitis.

The impact of medium dose UVA1 phototherapy on pruritus, DLQI and SCORAD index in patients with atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is featured by pruritus, which causes diminished quality of life. Little clinical data exists concerning the use, efficacy and side effects of UVA1 phototherapy in AD patients.

AIM

To determine the effectiveness of medium-dose UVA1 phototherapy in AD treatment.

MATERIAL AND METHODS

Thirty-six patients with AD were irradiated with medium-dose UVA1 (45 J/cm2) as monotherapy for 4 weeks for a total of 20 sessions (daily irradiations during weekdays only). Clinical status was evaluated with the visual analogue scale for pruritus, Dermatology Life Quality Index (DLQI) for evaluating general well-being and the SCORAD index. All parameters were measured twice: before and after phototherapy.

RESULTS

UVA1 phototherapy resulted in a significant (p < 0.001) decrease in pruritus, improvement in DLQI (p < 0.001) and SCORAD (p < 0.001). Before phototherapy, the intensity of pruritus and SCORAD index correlated with DLQI (r = 0.34, p < 0.05 and r = 0.61, p < 0.05, respectively). Similarly, after irradiation, pruritus correlated with DLQI, and SCORAD index correlated with DLQI (r = 0.51, p < 0.05 and r = 0.55, p < 0.05, respectively). No severe adverse effects were noted during the study.

CONCLUSIONS

Phototherapy with medium-dose UVA1 irradiation exerts a significant antipruritic effect, decreases the severity of the disease and improves the quality of life of AD patients. This technique can therefore be used as a safe and effective treatment method.

Staphylococcal superantigen-like 12 induces the production of interleukin 4 in murine basophils

S. aureus is associated with atopic dermatitis (AD). Several staphylococcal products including cell wall components, protease, and exotoxins, are thought to be involved in allergic inflammation of AD via activating immune cells such as T cells and mast cells. None of the staphylococcal exotoxins has been reported to activate a primary IL-4 inducer, basophils, that are known to produce large amounts of IL-4 in response to allergens as well as IgE-independent stimuli such as mites and helminth proteases. In this study, we investigated the ability of staphylococcal superantigen-like (SSL) family to activate basophils. SSL12, reported its activity to activate mast cells, induced the production of IL-4 in bone marrow derived basophils. SSL12 also evoked the release of IL-4 in freshly isolated murine basophils in bone marrow cells, as the depletion of basophils by basophils-specific antibodies against high-affinity IgE receptor and CD49b diminished the responsiveness of bone marrow cells for SSL12. These results propose the novel immune regulatory activity of SSL12 by inducing IL-4 in basophils, that contributes to the development of allergic inflammation disorders and the immune evasion of the cocci.

Epigenetic alterations in skin homing CD4+CLA+ T cells of atopic dermatitis patients

T cells expressing the cutaneous lymphocyte antigen (CLA) mediate pathogenic inflammation in atopic dermatitis (AD). The molecular alterations contributing to their dysregulation remain unclear. With the aim to elucidate putative altered pathways in AD we profiled DNA methylation levels and miRNA expression in sorted T cell populations (CD4⁺, CD4⁺CD45RA⁺ naïve, CD4⁺CLA⁺, and CD8⁺) from adult AD patients and healthy controls (HC). Skin homing CD4⁺CLA⁺ T cells from AD patients showed significant differences in DNA methylation in 40 genes compared to HC (p < 0.05). Reduced DNA methylation levels in the upstream region of the interleukin-13 gene (IL13) in CD4⁺CLA⁺ T cells from AD patients correlated with increased IL13 mRNA expression in these cells. Sixteen miRNAs showed differential expression in CD4⁺CLA⁺ T cells from AD patients targeting genes in 202 biological processes (p < 0.05). An integrated network analysis of miRNAs and CpG sites identified two communities of strongly interconnected regulatory elements with strong antagonistic behaviours that recapitulated the differences between AD patients and HC. Functional analysis of the genes linked to these communities revealed their association with key cytokine signaling pathways, MAP kinase signaling and protein ubiquitination. Our findings support that epigenetic mechanisms play a role in the pathogenesis of AD by affecting inflammatory signaling molecules in skin homing CD4⁺CLA⁺ T cells and uncover putative molecules participating in AD pathways.

Food allergy and atopic dermatitis

Atopic dermatitis (AD), characterized by intense pruritus, eczematous lesions, and a relapsing disease course, is a chronic inflammatory skin disease that affects both children and adults. AD often begins in infancy and is associated with atopic diseases in the personal or family history.1 Environmental factors may trigger AD by affecting the skin barrier and by triggering inflammation. The elicitation of T-helper type 2 cytokines further impairs the epidermal barrier and leads to the penetration of irritants and allergens into the epidermis and thereby perpetuating inflammation. The presence of AD and its severity has been shown to positively correlate with risk of developing food allergy (FA). Children with AD are estimated to be six times more likely to develop FA compared with their healthy peers. It has been reported that nearly 40% of children with moderate-to-severe AD have immunoglobulin E (IgE) mediated FA compared with only 6% in the general population. Although analysis of experimental data has linked skin inflammation in AD to FA, with food challenges reproducing symptoms and avoidance diets improving AD, elimination diets are not known to cure AD and may have unfavorable consequences, such as loss of tolerance, which leads to immediate-type allergy, including anaphylaxis, nutritional deficiencies, growth failure, and reduction of quality of life for the patient and family. Exacerbation of AD can be inaccurately attributed to foods. Individuals with AD are often sensitized to foods with positive testing results, however, able to tolerate the food. In light of widespread ordering and commercial availability of serum specific IgE for FA, testing for FA is recommended only if, from a detailed clinical history, immediate-type allergic symptoms occur with ingestion of food, or in infants with AD who do not improve with optimal skin care.

Management of Allergic Patients During the COVID-19 Pandemic in Asia

Although a viral infection is a major triggering factor of asthma and allergic diseases, asthma is suggested to be not a predisposing condition for coronavirus disease 2019 (COVID-19) infection. However, patients with severe asthma/allergic disease requiring systemic corticosteroids or immunosuppressive agents may be at higher risk of more severe clinical course of this infectious disease. For allergic patients who have been followed up at an allergy clinic in our region, it is recommended that they (patients with asthma, rhinitis, atopic dermatitis or chronic urticaria) continue to receive maintenance therapy and be in a well-controlled status. Patients who have used biologics (currently available for targeting type 2 inflammation) and allergen immunotherapy should continue the treatment while minimizing hospital and face-to-face visits. It is essential to wear protective equipment for the protection of health care workers as well as patients. We report this consensus to support allergists and clinical immunologists to make optimal decisions under the urgent situation in Asia.

IL-15 Expression Pattern in Atopic Dermatitis

BACKGROUND

An increased expression of interleukin (IL)-15, a cytokine with a key role in stimulating innate and adaptive immune cells, such as dendritic cells (DC), natural killer cells, and T cells, has been observed in infectious and inflammatory diseases, including autoimmune diseases as well as cancer. Atopic dermatitis (AD) is a common inflammatory skin disease characterized by a type 2 immune response.

OBJECTIVE

To explore the expression of IL-15 and its pattern in AD skin.

METHOD

Immunofluorescence staining was performed on skin specimens of AD skin, nonlesional AD skin (AD NL), and normal skin (NS) using antibodies directed against IL-15 and CD3, mast cell tryptase, eosinophil cationic protein, CD68, CD11b, CD1a, and vimentin.

RESULTS

A significantly higher IL-15 expression in AD and AD NL was observed in both the epidermis (p = 0.0003) and the dermis (p = 0.0154) as compared to NS. Cells expressing IL-15 were mainly keratinocytes, CD1a+ DC, CD11b+ DC, CD68+ macrophages, and vimentin+ fibroblasts. In AD, an increase in the relative numbers of IL-15 expressing CD1a+ DC, macrophages, and fibroblasts was noted.

CONCLUSION

Our results demonstrate an expression of IL-15 in AD similar to that of eosinophilic esophagitis which is also a type 2 disease. IL-15 may serve as a therapeutic target for AD.

Recent Advances in Clinical Allergy and Immunology 2019

The immune system has vital functions for homeostasis and host defense. Thus, imbalances of the immune system whether associated with allergy, hypersensitivity, or autoimmunity are of great importance, as is manifest from common diseases such as atopic diseases, urticaria, and angioedema, and drug hypersensitivity reactions. These can affect patients' quality of life and can generate high costs for health care. Epidemiological studies have provided evidence for changing patterns of allergic diseases caused by lifestyle and climate changes which have consequences for medical care. Deeper insights into the pathogenesis of allergic/immunologic diseases, combined with novel technologies, provide improved diagnostic options and treatment measures. This review will summarize novel aspects of the epidemiology, pathogenic mechanisms, as well as disease management in the fields of allergy and clinical immunology.

Allergy and Atopic Diseases: An Update on Experimental Evidence

Over the last decades, an increasing appearance of allergies and atopic disorders, such as asthma, dermatitis, and rhinitis, has been observed. The mechanisms of these disorders remain unclear, and therefore the development of novel therapies is limited. Current treatments are often symptomatic, nonspecific, or may have severe side effects. Further insights into the mechanisms of the underlying disease pathogenesis could reveal novel targets for treatment. In this review, we provide an update on recent basic and translational studies that offer novel insights and opportunities for the treatment of patients with atopic disorders.

Elevated Gestational IL-13 During Fetal Development Is Associated With Hyperactivity and Inattention in Eight-Year-Old Children

Maternal immune activation (MIA) during fetal development leads to behavioral and psychological disorders in the offspring. Concomitantly, insufficient supply of polyunsaturated fatty acids (PUFAs) is suspected to contribute to early neuronal maldevelopment due to the immune modulatory capabilities of PUFAs. However, human data are missing considering both of these aspects and their impact on children's behavioral outcomes. In line, this study aimed to elucidate the influence of gestational cytokines and PUFA-containing lipids during late pregnancy on behavioral sequelae in childhood, particularly focusing on an immune activation shaped by a history of maternal atopic diseases instead of a pathogen-mediated immune response. Based on the prospective mother-child cohort LINA we assessed the unstimulated blood cytokine profiles and concentrations of PUFA-containing lipids of 293 mothers at the 34th week of pregnancy. Maternal history of atopic diseases was obtained from questionnaires and behavior in eight-year-old children was assessed by the standardized Strength and Difficulties Questionnaires (SDQ) generating scores for hyperactivity/inattention, emotional symptoms, conduct problems, and peer relationship problems. Elevated IL-13 increased the risk for the child to show behavioral difficulties, in particular, hyperactive/inattentive behavior [adj. OR (95% CI): 2.47 (1.51-4.02), n = 255 vs. 38] at the age of eight years. Although the presence of maternal atopic dermatitis (AD) was associated with increased gestational IL-13 concentrations [adj. MR (95% CI): 1.17 (1.04-1.32)], no effect on children's behavioral difficulties was observed. However, a decrease in the PUFA containing lipid species PC aa C38:6 was not only associated with an increased gestational IL-13 concentration but also mediated the indirect effect of low PC aa C38:6 concentrations on children's abnormal behavior independent of maternal AD. We additionally assessed whether maternal IL-13 and PC aa C38:6 concentrations translate their effect by altering children's cord blood PC aa C38:6 and IL-13. While also the children's cord blood IL-13 was related to children's behavior, no effect of children's PC aa C38:6 was observed. This is the first study demonstrating that elevated gestational IL-13 increases the risk for children to develop behavioral difficulties. Analyses suggest that a reduced supply of gestational PC aa C38:6 contributes to elevated gestational IL-13 leading to behavioral sequelae in the offspring.