Patrick M. Brunner

Increasing Comorbidities Suggest that Atopic Dermatitis Is a Systemic Disorder

Atopic dermatitis comorbidities extend well beyond the march to allergic conditions (food allergy, asthma, allergic rhinitis, allergic conjunctivitis, and eosinophilic esophagitis), suggesting both cutaneous and systemic immune activation. In reviewing atopic dermatitis comorbidities, Councilors of the International Eczema Council found a strong pattern of immune activation in peripheral blood and the propensity to both skin and systemic infections. Associations with cardiovascular, neuropsychiatric, and malignant diseases were increasingly reported, but confirmation of their link with atopic dermatitis requires longitudinal studies. Given the possibility of atopic dermatitis-related systemic immune activation, future investigations of new interventions should concurrently examine the impact on these comorbidities.

Efficacy and safety of ustekinumab treatment in adults with moderate-to-severe atopic dermatitis.

Atopic dermatitis (AD) is the most common inflammatory skin disease, but treatment options for moderate‐to‐severe disease are limited. Ustekinumab is an IL‐12/IL‐23p40 antagonist that suppresses Th1, Th17 and Th22 activation, commonly used for psoriasis patients. We sought to assess efficacy and safety of ustekinumab in patients with moderate‐to‐severe AD. In this phase II, double‐blind, placebo‐controlled study, 33 patients with moderate‐to‐severe AD were randomly assigned to either ustekinumab (n=16) or placebo (n=17), with subsequent crossover at 16 weeks, and last dose at 32 weeks. Background therapy with mild topical steroids was allowed to promote retention. Study endpoints included clinical (SCORAD50) and biopsy‐based measures of tissue structure and inflammation, using protein and gene expression studies. The ustekinumab group achieved higher SCORAD50 responses at 12, 16 (the primary endpoint) and 20 weeks compared to placebo, but the difference between groups was not significant. The AD molecular profile/transcriptome showed early robust gene modulation, with sustained further improvements until 32 weeks in the initial ustekinumab group. Distinct and more robust modulation of Th1, Th17 and Th22 but also Th2‐related AD genes was seen after 4 weeks of ustekinumab treatment (i.e. MMP12, IL‐22, IL‐13, IFN‐γ, elafin/PI3, CXCL1 and CCL17; P<.05). Epidermal responses (K16, terminal differentiation) showed faster (4 weeks) and long‐term regulation (32 weeks) from baseline in the ustekinumab group. No severe adverse events were observed. Ustekinumab had clear clinical and molecular effects, but clinical outcomes might have been obscured by a profound “placebo” effect, most likely due to background topical glucocorticosteroids and possibly insufficient dosing for AD.

Immunologic, microbial, and epithelial interactions in atopic dermatitis

OBJECTIVE To provide an overview of studies contributing to the understanding of immunologic, microbial, and epithelial interactions in atopic dermatitis. DATA SOURCES PubMed literature review (2000-2017) and meeting abstracts from recent international dermatology conferences. STUDY SELECTIONS Articles discussing primarily human disease. RESULTS Clinical studies showed that atopic dermatitis is a type 2 immune-centered disease with a systemic inflammatory component but with heterogeneous treatment responses. This suggests that other factors are likely involved in shaping the skin disease phenotype, including microbial dysbiosis and epidermal barrier dysfunction. CONCLUSION Recent clinical investigation has significantly expanded our knowledge on disease pathogenesis in atopic dermatitis, and current and future clinical trials will most likely further help to elucidate this complex, heterogeneous skin disease.

Efficacy and safety of fezakinumab (an IL-22 monoclonal antibody) in adults with moderate-to-severe atopic dermatitis inadequately controlled by conventional treatments: A randomized, double-blind, phase 2a trial

Background: Interleukin 22 promotes epidermal hyperplasia and inhibits skin barrier function. Objective: Evaluate interleukin 22 blockade in adults with moderate‐to‐severe atopic dermatitis (AD). Methods: We performed a randomized, double‐blind, placebo‐controlled trial with intravenous fezakinumab monotherapy every 2 weeks for 10 weeks, with follow‐up assessments until 20 weeks. The change in SCOring AD (SCORAD) score from baseline at 12 weeks served as the primary end point. Results: At 12 weeks, the mean declines in SCORAD for the entire study population were 13.8 ± 2.7 in the fezakinumab arm and 8.0 ± 3.1 in the placebo arm (P = .134). In the severe AD patient subset (with a baseline SCORAD of ≥50), SCORAD decline was significantly stronger in the drug‐treated patients than placebo‐treated patients at 12 weeks (21.6 ± 3.8 vs 9.6 ± 4.2, P = .029) and 20 weeks (27.4 ± 3.9 vs 11.5 ± 5.1, P = .010). At 12 weeks, improvements in body surface area involvement in the entire population were significantly stronger in the drug‐treated than placebo‐treated patients (12.4% ± 2.4 vs 6.2% ± 2.7; P = .009), and in the severe AD subset, the decline in Investigator Global Assessment was significantly higher in the drug‐treated than placebo‐treated patients (0.7 ± 0.2 vs 0.3 ± 0.1; P = .034). All scores showed progressive improvements after last dosing (10 weeks) until end of study (20 weeks). Common adverse events were upper respiratory tract infections. Limitations: The limited sample size and lack of assessment with Eczema Area and Severity Index and a pruritus numerical rating scale were limiting factors. Significance was primarily obtained in severe AD. Conclusion: Fezakinumab was well‐tolerated, with sustained clinical improvements after last drug dosing.

Alterations in B-cell subsets in pediatric patients with early atopic dermatitis

Background B cells undergo maturation and class‐switching in response to antigen exposure and T‐cell help. Early B‐cell differentiation has not been defined in patients with early‐onset atopic dermatitis (AD). Objective We sought to define the frequency of B‐cell subsets associated with progressive B‐cell maturation and IgE class‐switching. Methods We studied 27 children and 34 adults with moderate‐to‐severe AD (mean SCORAD score, 55 and 65, respectively) and age‐matched control subjects (15 children and 27 adults). IgD/CD27 and CD24/CD38 core gating systems and an 11‐color flow cytometric panel were used to determine the frequencies of circulating B‐cell subsets. Serum total and allergen‐specific IgE (sIgE) levels were measured by using ImmunoCAP. Results Compared with adults, children showed T‐cell predominance in the skin. Circulating CD19+CD20+ B‐cell counts were lower in patients with pediatric AD than in control subjects (24% vs 33%, P = .04), whereas CD3+ T‐cell counts were higher (62% vs 52%, P = .05). A decreased B‐cell/T‐cell lymphocyte ratio with age was observed only in pediatric control subjects (r = −0.48, P = .07). In pediatric patients with AD, a positive correlation was observed between B‐cell/T‐cell ratio and nonswitched memory B‐cell counts (r = 0.42, P = .03). Higher frequencies of positive sIgE levels were seen in pediatric patients with AD (P < .0001). Diverse sIgE levels correlated with SCORAD scores and age of pediatric patients with AD (P < .01). Positive correlations were observed between activated B‐cell and memory T‐cell counts (P < .02). In patients with AD, IgE sensitization to most allergens clustered with age, TH1, TH2, total IgE levels, and B‐cell memory subsets. Conclusions Peripheral B and T cells are altered in pediatric patients with early AD, but T cells predominate in skin lesions.

Interleukin‐17 Alters the Biology of Many Cell Types Involved in the Genesis of Psoriasis, Systemic Inflammation, and Associated Comorbidities

Psoriasis is a chronic, immune‐mediated, systemic inflammatory disease that is defined by a characteristic skin reaction produced when elevated levels of inflammatory cytokines such as interleukin (IL)‐17 alter the growth and differentiation of skin cells. The pathogenesis of comorbid conditions associated with psoriasis, including psoriatic arthritis, cardiovascular disease, obesity, metabolic syndrome, liver disorders, renal disease and depression, is also largely affected by inflammation. In this review, we examine the effect of IL‐17 on the inflammatory pathways in a variety of different cell types, including keratinocytes, as well as epithelial cells of the colon, kidney, gut and liver. Additionally, we investigate the role of IL‐17 in mediating the psoriasis‐associated comorbidities detailed above.

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.

Early-onset pediatric atopic dermatitis is characterized by T H 2/T H 17/T H 22-centered inflammation and lipid alterations

Background: Although atopic dermatitis (AD) often starts in early childhood, detailed tissue profiling of early‐onset AD in children is lacking, hindering therapeutic development for this patient population with a particularly high unmet need for better treatments. Objective: We sought to globally profile the skin of infants with AD compared with that of adults with AD and healthy control subjects. Methods: We performed microarray, RT‐PCR, and fluorescence microscopy studies in infants and young children (<5 years old) with early‐onset AD (<6 months disease duration) compared with age‐matched control subjects and adults with longstanding AD. Results: Transcriptomic analyses revealed profound differences between pediatric patients with early‐onset versus adult patients with longstanding AD in not only lesional but also nonlesional tissues. Although both patient populations harbored TH2‐centered inflammation, pediatric AD also showed significant TH17/TH22 skewing but lacked the TH1 upregulation that characterizes adult AD. Pediatric AD exhibited relatively normal expression of epidermal differentiation and cornification products, which is downregulated in adults with AD. Defects in the lipid barrier (eg, ELOVL fatty acid elongase 3 [ELOVL3] and diacylglycerol o‐acyltransferase 2 [DGAT2]) and tight junction regulation (eg, claudins 8 and 23) were evident in both groups. However, some lipid‐associated mediators (eg, fatty acyl‐CoA reductase 2 and fatty acid 2‐hydroxylase) showed preferential downregulation in pediatric AD, and lipid barrier genes (FA2H and DGAT2) showed inverse correlations with transepidermal water loss, a functional measure of the epidermal barrier. Conclusions: Skin samples from children and adult patients with AD share lipid metabolism and tight junction alterations, but epidermal differentiation complex defects are only present in adult AD, potentially resulting from chronic immune aberration that is not yet present in early‐onset disease.

Nonlesional atopic dermatitis skin shares similar T‐cell clones with lesional tissues

Atopic dermatitis (AD) is characterized by robust immune activation. Various T‐cell subsets, including Th2/Th22 cells, are increased in lesional and nonlesional skin. However, there is conflicting literature on the diversity of the T‐cell receptor (TCR) repertoire in lesional AD, and its relation to nonlesional skin remains unclear.

Baseline IL-22 expression in patients with atopic dermatitis stratifies tissue responses to fezakinumab

Background: IL‐22 is potentially a pathogenic cytokine in patients with atopic dermatitis (AD), but the molecular effects of IL‐22 antagonism have not been defined in human subjects. Objective: We sought to evaluate the cellular and molecular effects of IL‐22 blockade in tissues from patients with moderate‐to‐severe AD. Methods: We assessed lesional and nonlesional skin from 59 patients with moderate‐to‐severe AD treated with anti–IL‐22 (fezakinumab) versus placebo (2:1) using transcriptomic and immunohistochemistry analyses. Results: Greater reversal of the AD genomic profile was seen with fezakinumab versus placebo, namely 25.3% versus 10.5% at 4 weeks (P = 1.7 × 10−5) and 65.5% versus 13.9% at 12 weeks (P = 9.5 × 10−19), respectively. Because IL‐22 blockade showed clinical efficacy only in patients with severe AD, we used baseline median IL‐22 mRNA expression to stratify for high (n = 30) and low (n = 29) IL‐22 expression groups. Much stronger mean transcriptomic improvements were seen with fezakinumab in the IL‐22–high drug‐treated group (82.8% and 139.4% at 4 and 12 weeks, respectively) than in the respective IL‐22–high placebo‐treated group (39.6% and 56.3% at 4 and 12 weeks) or the IL‐22–low groups. Significant downregulations of multiple immune pathways, including TH1/CXCL9, TH2/CCL18/CCL22, TH17/CCL20/DEFB4A, and TH22/IL22/S100As, were restricted to the IL‐22–high drug group (P < .05). Consistently, tissue predictors of clinical response were mostly genes involved in T‐cell and dendritic cell activation and differentiation. Conclusions: This is the first report showing a profound effect of IL‐22 blockade on multiple inflammatory pathways in AD. These data, supported by robust effects in patients with high IL‐22 baseline expression, suggest a central role for IL‐22 in AD, indicating the need for a precision medicine approach for improving therapeutic outcomes in patients with AD.