Increasing Comorbidities Suggest that Atopic Dermatitis Is a Systemic Disorder

Effect of isoliquiritigenin for the treatment of atopic dermatitis-like skin lesions in mice

Atopic dermatitis (AD) is a common chronic inflammatory skin disease characterized with high heterogeneity. Recent studies have suggested that it is driven by both terminal keratinocyte differentiation defects and type 2 immune responses. The mainstay steroid topical therapy has severe side effect and new treatment is in demand. Isoliquiritigenin (ISLG) is a small phenolic bioactive molecule from licorice that has shown multiple pharmacological effects against cancer, inflammatory disorder, and cardiovascular diseases. ISLG was evaluated in AD-like lesion model induced by the repetitive application of 2,4-dinitrochlorobenzene (DNCB) in BALB/c mice. Overall symptom score, serological and molecular changes of the skin lesions were evaluated. ISLG could ameliorate the overall manifestation of AD-like symptoms including scratching behavior incidence and skin lesion severity. At blood level, ISLG significantly suppressed the DNCB-induced IgE and Th2 cytokines up-regulation. At skin lesion site, ISLG also inhibited DNCB-induced pro-inflammatory cytokines like TNF-α, IL-6 as well as IL-4 expressions. In a human monocyte model THP-1, ISLG suppressed the up-regulation of CD86 and CD54 and abolished the DNCB-induced p38-α and ERK activation, suggesting a molecular mechanism for ISLG therapy. This study indicated that ISLG could be a potential therapeutic agent for the treatment of AD.

Expert Perspectives on Management of Moderate-to-Severe Atopic Dermatitis: A Multidisciplinary Consensus Addressing Current and Emerging Therapies

Atopic dermatitis (AD) is a common, chronic, relapsing, inflammatory skin disease that affects children and adults. Until recently, the only Food and Drug Administration-approved systemic treatment option for patients with moderate-to-severe AD was systemic steroids, which are not recommended by current guidelines and are commonly associated with disease rebound. Instead, clinicians choose from several off-label immunosuppressants, which can have serious adverse effects. A significant number of these patients go untreated. Research on the immunopathogenesis of AD has paved the way for new, targeted, systemic therapies for moderate-to-severe AD. In early 2017, the Food and Drug Administration approved dupilumab for adults with moderate-to-severe AD whose disease is not adequately controlled with topical therapies. Although the national guidelines can be very helpful to clinicians, the process for updating them does not allow for timely incorporation of novel therapies. A steering committee of AD experts, including dermatologists, allergists, and a patient advocacy group representative, developed recommendations on the basis of a literature review and expert opinion to help clinicians understand how new therapies fit into the current treatment paradigm and to provide practical recommendations for assessing AD severity, treatment response, and treatment failure.

Moderate-to-severe atopic dermatitis patients show increases in serum C-reactive protein levels, correlating with skin disease activity

Background: Atopic dermatitis (AD), the most common chronic inflammatory skin disease, is evolving as a systemic disease, and associated systemic inflammation is possibly linked to increases in cardiovascular disease.

Methods: We assessed levels of the inflammatory marker CRP in 59 patients with moderate-to-severe AD compared to matched healthy controls, and to determine correlation with skin disease severity. Clinical severity was measured using SCORing of Atopic Dermatitis (SCORAD) and body surface area (BSA). Control subjects (n=118), matched by age, gender, smoking status and ethnicity, were obtained from the National Health and Nutrition Survey (NHANES).

Results: AD patients had significantly increased serum CRP levels compared to controls (0.7±1.0 vs. 0.4±0.7mg/dl; p=0.001), and 52.5% of them showed CRP levels >0.3mg/dl, predicting high cardiovascular risk. CRP levels were significantly correlated with both SCORAD (r=0.427, p=0.0008) and BSA (r=0.407, p=0.0015).  IgE levels in AD were highly elevated (median 2903U/ml, IQR [234,10655]), but only weakly correlated with SCORAD (r=0.282, p=0.0427) and BSA (r=0.382, p=0.0052), but not with CRP levels. AD patients also showed increased LDH levels, but without significant correlations with disease severity (SCORAD, BSA) or CRP.

Conclusions: Our study strongly supports CRP as a marker for disease severity in moderate-to-severe AD patients, further demonstrating its chronic systemic nature.

Etiology of epithelial barrier dysfunction in patients with type 2 inflammatory diseases

Epithelial barriers of the skin, gastrointestinal tract, and airway serve common critical functions, such as maintaining a physical barrier against environmental insults and allergens and providing a tissue interface balancing the communication between the internal and external environments. We now understand that in patients with allergic disease, regardless of tissue location, the homeostatic balance of the epithelial barrier is skewed toward loss of differentiation, reduced junctional integrity, and impaired innate defense. Importantly, epithelial dysfunction characterized by these traits appears to pre-date atopy and development of allergic disease. Despite our growing appreciation of the centrality of barrier dysfunction in initiation of allergic disease, many important questions remain to be answered regarding mechanisms disrupting normal barrier function. Although our external environment (proteases, allergens, and injury) is classically thought of as a principal contributor to barrier disruption associated with allergic sensitization, there is a need to better understand contributions of the internal environment (hormones, diet, and circadian clock). Systemic drivers of disease, such as alterations of the endocrine system, metabolism, and aberrant control of developmental signaling, are emerging as new players in driving epithelial dysfunction and allergic predisposition at various barrier sites. Identifying such central mediators of epithelial dysfunction using both systems biology tools and causality-driven laboratory experimentation will be essential in building new strategic interventions to prevent or reverse the process of barrier loss in allergic patients.

The atopic dermatitis blood signature is characterized by increases in inflammatory and cardiovascular risk proteins

Beyond classic “allergic”/atopic comorbidities, atopic dermatitis (AD) emerges as systemic disease with increased cardiovascular risk. To better define serum inflammatory and cardiovascular risk proteins, we used an OLINK high-throughput proteomic assay to analyze moderate-to-severe AD (n = 59) compared to psoriasis (n = 22) and healthy controls (n = 18). Compared to controls, 10 proteins were increased in serum of both diseases, including Th1 (IFN-γ, CXCL9, TNF-β) and Th17 (CCL20) markers. 48 proteins each were uniquely upregulated in AD and psoriasis. Consistent with skin expression, AD serum showed up-regulation of Th2 (IL-13, CCL17, eotaxin-1/CCL11, CCL13, CCL4, IL-10), Th1 (CXCL10, CXCL11) and Th1/Th17/Th22 (IL-12/IL-23p40) responses. Surprisingly, some markers of atherosclerosis (fractalkine/CX3CL1, CCL8, M-CSF, HGF), T-cell development/activation (CD40L, IL-7, CCL25, IL-2RB, IL-15RA, CD6) and angiogenesis (VEGF-A) were significantly increased only in AD. Multiple inflammatory pathways showed stronger enrichment in AD than psoriasis. Several atherosclerosis mediators in serum (e.g. E-selectin, PI3/elafin, CCL7, IL-16) correlated with SCORAD, but not BMI. Also, AD inflammatory mediators (e.g. MMP12, IL-12/IL-23p40, CXCL9, CCL22, PI3/Elafin) correlated between blood and lesional as well as non-lesional skin. Overall, the AD blood signature was largely different compared to psoriasis, with dysregulation of inflammatory and cardiovascular risk markers, strongly supporting its systemic nature beyond atopic/allergic association.

Atopic Dermatitis and Comorbidities: Added Value of Comprehensive Dermatoepidemiology

Atopic dermatitis is common and in its severe form is devastating. This chronic inflammatory dermatosis is part of the atopic syndrome, which includes asthma, food allergies, and hay fever and is known to be associated with mental health disorders. In line with psoriasis, several recent observational studies using national survey and linkage data have suggested a link between atopic dermatitis and cardiovascular disease. The atopic dermatitis field can benefit from the past experiences in psoriasis research and should not follow the same path, but, rather, aim for a more comprehensive approach from the beginning. A recent German consortium studying links between atopic dermatitis and cardiovascular disease first screened a large claims database, followed by analyses of more deeply phenotyped (birth) cohorts with longitudinal data. In addition, genetic and metabolic analyses assessing the predisposition of patients with atopic dermatitis for cardiovascular disease were performed. Overall, the association between atopic dermatitis and cardiovascular disease was at most modest, but in more refined cohorts the cardiovascular risk profile and genetic architecture was comparable. A more integrated approach could create clarity about the clinical relevance of cardiovascular disease in individuals with atopic dermatitis sooner, avoid speculation that affects patient care, and save scientific resources.

Association of atopy and tentative diagnosis of skin cancer - results from occupational skin cancer screenings

BACKGROUND

The relationship between atopic conditions and carcinoma of the skin has been described inconsistently. Population-based data providing information on atopic diseases as well as on skin cancer are sparse.

OBJECTIVE

To determine the correlation between atopy and prevalence of precanceroses, non-melanoma skin cancer and malignant melanoma (MM), while taking into account known risk factors for skin cancer.

METHODS

Data from occupational skin cancer screenings were analysed in a cross-sectional study. Dermatologists performed whole body examinations and collected medical histories. Subjects comprised all employees (16-70 years) examined from 2006 to 2014. 'Atopy' was defined by clinical screening diagnosis and/or by participant-reported, pre-existing atopic dermatitis, allergic asthma or other specified allergies confirmed by a physician. Tentative screening diagnoses of skin cancer related to actinic keratosis, basal cell carcinoma and malignant melanoma.

RESULTS

The study cohort comprised 90 265 employees (mean age 43 ± 11 years, 58.5% male), 30.7% of whom were ever diagnosed with an atopic disease. Persons with atopic conditions recorded in their medical history and at the time of screening had a significantly lower prevalence of actinic keratosis (AK), basal cell carcinoma (BCC) and MM. After controlling for age, sex and relevant risk factors (skin type, childhood sun burns), atopy remained significantly protective against BCC (OR 0.77) and MM (OR 0.53).

CONCLUSION

Design limitations of the study include that all findings of skin cancer were based on clinical examination only and must therefore be considered tentative diagnoses. Furthermore, owing to the cross-sectional study design, causal pathways cannot be proven. However, analyses of data from such a large and general population-based cohort afford valuable insights into the relationship between atopic diseases and skin cancer. They provide the grounds for prospective cohort studies to evaluate and dissect the underlying mechanism.

The immunology of atopic dermatitis and its reversibility with broad-spectrum and targeted therapies

Atopic dermatitis (AD), the most common chronic inflammatory skin disease, is driven by both terminal keratinocyte differentiation defects and strong type 2 immune responses. In contrast to chronic plaque-type psoriasis, AD is now understood to be a much more heterogeneous disease, with additional activation of T_H22, T_H17/IL-23, and T_H1 cytokine pathways depending on the subtype of the disease. In this review we discuss our current understanding of the AD immune map in both patients with early-onset and those with chronic disease. Clinical studies with broad and targeted therapeutics have helped to elucidate the contribution of various immune axes to the disease phenotype. Importantly, immune activation extends well beyond lesional AD because nonlesional skin and the blood component harbor AD-specific inflammatory changes. For this reason, future therapeutics will need to focus on a systemic treatment approach, especially in patients with moderate-to-severe disease.

Advances in atopic dermatitis and urticarial in 2016

This review highlights recent key advances in the pathology and therapies of inflammatory skin diseases, focusing on atopic dermatitis (AD) and chronic spontaneous urticaria (CSU). Regarding AD, transcriptomic analysis with human samples revealed different immune profiles between childhood and adult AD. Phase III clinical trials of dupilumab, an anti-IL-4 receptor α antibody, in the treatment of AD have successfully finished, and dupilumab will appear in clinical practice as the first biologic for AD in 2017. In addition, a novel biologic that targets IL-31 shows promising results in a phase II trial. As for the skin microbiome study, novel insights into the mechanisms of microbial dysbiosis, such as colonization of Staphylococcus aureus, a common feature of AD, were proposed. Regarding CSU, autoreactive CD4⁺ T cells that react to FcεRI were discovered, which might contribute to the development of CSU. These findings provide new insights into the pathogenesis of AD and CSU and will lead to more specific and personalized treatments.

"Inflammatory skin march" in atopic dermatitis and psoriasis

BACKGROUND

Comorbidities of cardiovascular diseases (CVDs), metabolic syndrome and autoimmune diseases with systemic inflammation are recent topics in medicine. Inflammatory skin diseases such as atopic dermatitis and psoriasis are an active source of diverse proinflammatory cytokines and chemokines, which are readily detectable in the circulation and are likely to be involved in developing comorbidities.

EVIDENCE

Both atopic dermatitis and psoriasis are frequently comorbid with CVD, metabolic syndrome and autoimmune diseases, the consequence of which is called "inflammatory skin march", "psoriatic march" or "march of psoriasis".

CONCLUSION

In this review, we summarize the epidemiological evidence and pathogenetic concepts regarding inflammatory skin march in atopic dermatitis and psoriasis.

The etiopathogenesis of atopic dermatitis: barrier disruption, immunological derangement, and pruritus

Atopic dermatitis (AD) is a common chronic skin inflammatory disorder characterized by recurrent eczema accompanied by an intractable itch that leads to an impaired quality of life. Extensive recent studies have shed light on the multifaceted pathogenesis of the disease. The complex interplay among skin barrier deficiency, immunological derangement, and pruritus contributes to the development, progression, and chronicity of the disease. Abnormalities in filaggrin, other stratum corneum constituents, and tight junctions induce and/or promote skin inflammation. This inflammation, in turn, can further deteriorate the barrier function by downregulating a myriad of essential barrier-maintaining molecules. Pruritus in AD, which may be due to hyperinnervation of the epidermis, increases pruritogens, and central sensitization compromises the skin integrity and promotes inflammation. There are unmet needs in the treatment of AD. Based on the detailed evidence available to date, certain disease mechanisms can be chosen as treatment targets. Numerous clinical trials of biological agents are currently being conducted and are expected to provide treatments for patients suffering from AD in the future. This review summarizes the etiopathogenesis of the disease and provides a rationale for choosing the novel targeted therapy that will be available in the future.

Systemic immune mechanisms in atopic dermatitis and psoriasis with implications for treatment

Atopic dermatitis (AD) and psoriasis are inflammatory skin diseases that negatively affect patients' quality of life. Although distinctions exist between these diseases, both are characterized by erythematous, thickened epidermal lesions that vary in intensity and affected body surface area. Early models of aetiology attributed symptoms of both diseases to cutaneous inflammation at lesion sites, but recent studies have established that activated immune mediators in the circulation drive disease severity. Activation of T helper 2 (Th2) and Th22 cells in the circulation appears to be the principal initiator of acute AD pathology, with the emergence of Th1 and Th17/interleukin (IL)-23 pathway activation marking the transition to a chronic state. The Th17/IL-23 pathway also has an important role in psoriasis. The role of systemic inflammation in AD and psoriasis is supported by the occurrence of non-cutaneous comorbidities that affect patients, most of which intensify morbidity and disability associated with lesional skin. Atopic dermatitis is associated with allergic disorders consisting of the "atopic march," whereas psoriasis is frequently accompanied by psoriatic arthritis. Patients with both disorders are at significantly higher risk of obesity, metabolic disorders, and cardiovascular diseases, all of which feature inflammatory components in their pathology models. These insights have led to novel therapeutics aimed at addressing psoriasis by targeting tumor necrosis factor- and Th17-related cytokine pathways. The success of these agents in psoriasis management is driving new therapeutic approaches for moderate-to-severe AD, including agents targeting the Th2 and Th17/Th22 cytokine pathways.