Tiffany C. Scharschmidt

Estrogen receptor beta-selective transcriptional activity and recruitment of coregulators by phytoestrogens.

Estrogens used in hormone replacement therapy regimens may increase the risk of developing breast cancer. Paradoxically, high consumption of plant-derived phytoestrogens, particularly soybean isoflavones, is associated with a low incidence of breast cancer. To explore the molecular basis for these potential different clinical outcomes, we investigated whether soybean isoflavones elicit distinct transcriptional actions from estrogens. Our results demonstrate that the estrogen 17β-estradiol effectively triggers the transcriptional activation and repression pathways with both estrogen receptors (ERs) ERα and ERβ. In contrast, soybean isoflavones (genistein, daidzein, and biochanin A) are ERβ-selective agonists of transcriptional repression and activation at physiological levels. The molecular mechanism for ERβ selectivity by isoflavones involves their capacity to create an activation function-2 surface of ERβ that has a greater affinity for coregulators than ERα. Phytoestrogens may act as natural selective estrogen receptor modulators that elicit distinct clinical effects from estrogens used for hormone replacement by selectively recruiting coregulatory proteins to ERβ that trigger transcriptional pathways.

FILAGGRIN DEFICIENCY CONFERS A PARACELLULAR BARRIER ABNORMALITY THAT REDUCES INFLAMMATORY THRESHOLDS TO IRRITANTS AND HAPTENS

BACKGROUND Mutations in the human filaggrin gene (FLG) are associated with atopic dermatitis (AD) and are presumed to provoke a barrier abnormality. Yet additional acquired stressors might be necessary because the same mutations can result in a noninflammatory disorder, ichthyosis vulgaris. OBJECTIVE We examined here whether FLG deficiency alone suffices to produce a barrier abnormality, the basis for the putative abnormality, and its proinflammatory consequences. METHODS By using the flaky-tail mouse, which lacks processed murine filaggrin because of a frameshift mutation in the gene encoding profilaggrin that mimics some mutations in human AD, we assessed whether FLG deficiency provokes a barrier abnormality, further localized the defect, identified its subcellular basis, and assessed thresholds to irritant- and hapten-induced dermatitis. RESULTS Flaky-tail mice exhibit low-grade inflammation with increased bidirectional, paracellular permeability of water-soluble xenobiotes caused by impaired lamellar body secretion and altered stratum corneum extracellular membranes. This barrier abnormality correlates with reduced inflammatory thresholds to both topical irritants and haptens. Moreover, when exposed repeatedly to topical haptens at doses that produce no inflammation in wild-type mice, flaky-tail mice experience a severe AD-like dermatosis with a further deterioration in barrier function and features of a T(H)2 immunophenotype (increased CRTH levels plus inflammation, increased serum IgE levels, and reduced antimicrobial peptide [mBD3] expression). CONCLUSIONS FLG deficiency alone provokes a paracellular barrier abnormality in mice that reduces inflammatory thresholds to topical irritants/haptens, likely accounting for enhanced antigen penetration in FLG-associated AD.

Autosomal ichthyosis with hypotrichosis syndrome displays low matriptase proteolytic activity and is phenocopied in ST14 hypomorphic mice

Human autosomal recessive ichthyosis with hypotrichosis (ARIH) is an inherited disorder recently linked to homozygosity for a point mutation in the ST14 gene that causes a G827R mutation in the matriptase serine protease domain (G216 in chymotrypsin numbering). Here we show that human G827R matriptase has strongly reduced proteolytic activity toward small molecule substrates, as well as toward its candidate epidermal target, prostasin. To further investigate the possible contribution of low matriptase activity to ARIH, we generated an ST14 hypomorphic mouse strain that displays a 100-fold reduction in epidermal matriptase mRNA levels. Interestingly, unlike ST14 null mice, ST14 hypomorphic mice were viable and fertile but displayed a spectrum of abnormalities that strikingly resembled ARIH. Thus, ST14 hypomorphic mice developed hyperproliferative and retention ichthyosis with impaired desquamation, hypotrichosis with brittle, thin, uneven, and sparse hair, and tooth defects. Biochemical analysis of ST14 hypomorphic epidermis revealed reduced prostasin proteolytic activation and profilaggrin proteolytic processing, compatible with a primary role of matriptase in this process. This work strongly indicates that reduced activity of a matriptase-prostasin proteolytic cascade is the etiological origin of human ARIH and provides an important mouse model for the exploration of matriptase function in ARIH, as well as multiple other physiological and pathological processes.

Cutting Edge: Regulatory T Cells Facilitate Cutaneous Wound Healing.

Foxp3-expressing regulatory T cells (Tregs) reside in tissues where they control inflammation and mediate tissue-specific functions. The skin of mice and humans contain a large number of Tregs; however, the mechanisms of how these cells function in skin remain largely unknown. In this article, we show that Tregs facilitate cutaneous wound healing. Highly activated Tregs accumulated in skin early after wounding, and specific ablation of these cells resulted in delayed wound re-epithelialization and kinetics of wound closure. Tregs in wounded skin attenuated IFN-γ production and proinflammatory macrophage accumulation. Upon wounding, Tregs induce expression of the epidermal growth factor receptor (EGFR). Lineage-specific deletion of EGFR in Tregs resulted in reduced Treg accumulation and activation in wounded skin, delayed wound closure, and increased proinflammatory macrophage accumulation. Taken together, our results reveal a novel role for Tregs in facilitating skin wound repair and suggest that they use the EGFR pathway to mediate these effects.

Matriptase-Deficient Mice Exhibit Ichthyotic Skin with a Selective Shift in Skin Microbiota

Suppressor of tumorigenicity 14 (St14) encodes matriptase, a serine protease, which regulates processing of profilaggrin to filaggin in vivo. Here, we report that transgenic mice with 1% of wild-type St14 levels (St14(hypo/-)) display aberrant processing of profilaggrin and model human ichthyotic skin phenotypes. Scaling of the skin appears at 1 week of age with underlying epidermal acanthosis and orthohyperkeratosis as well as a CD4+ T-cell dermal infiltrate. Upregulation of antimicrobial peptides occurs when challenged by exposure to the postnatal environment. Direct genomic sequencing of bacterial 16S rRNA genes to query microbial diversity identifies a significant shift in both phylogeny and community structure between St14(hypo/-) mice and control littermates. St14(hypo/-) mice have a selective shift in resident skin microbiota with a decrease of the dominant genus of skin bacteria, Pseudomonas and an accompanying increase of Corynebacterium and Streptococcus. St14(hypo/-) mice provide early evidence that the cutaneous microbiome can be specifically altered by genetic state, which may play an important role in modulating skin disease.

Neurogenic Rosacea: A Distinct Clinical Subtype Requiring a Modified Approach to Treatment

Rosacea is generally categorized into 4 distinct clinical subtypes: erythematotelangiectatic, papulopustular, phymatous, and ocular.1 Granulomatous rosacea, rosacea fulminans, and perioral dermatitis have been described as additional variants.2 Herein we describe 14 patients with rosacea and prominent neurologic symptoms, who represent another distinct subset of rosacea meriting a unique approach to management.

Modeling Atopic Dermatitis with Increasingly Complex Mouse Models

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disorder that affects approximately 15% of children in the United States. A complex disorder, AD is characterized by both skin barrier impairment and immunologic abnormalities, including decreased innate immune function and a polarized adaptive immune response. Mouse models have demonstrated the complex interdependence of immune cell-keratinocyte interactions and teased apart gene-environment relationships in a controlled setting. In this issue, Nagelkerken et al. present a mouse model with transgenic expression of apolipoprotein C1 that disrupts the skin lipid barrier and manifests many hallmark features of AD.

Paradoxical Benefits of Psychological Stress in Inflammatory Dermatoses Models Are Glucocorticoid Mediated

Acute psychological stress (PS) mobilizes metabolic responses that are of immediate benefit to the host, but the current medical paradigm holds that PS exacerbates systemic and cutaneous inflammatory disorders. Although the adverse consequences of PS are usually attributed to neuroimmune mechanisms, PS also stimulates an increase in endogenous glucocorticoids (GCs) that compromises permeability barrier homeostasis, stratum corneum cohesion, wound healing, and epidermal innate immunity in normal skin. Yet, if such PS-induced increases in GC were uniformly harmful, natural selection should have eliminated this component of the stress response. Hence, we hypothesized here instead that stress-induced elevations in endogenous GC could benefit, rather than aggravate, cutaneous function and reduce inflammation in three immunologically diverse mouse models of inflammatory diseases. Indeed, superimposed exogenous (motion-restricted) stress reduced, rather than aggravated inflammation and improved epidermal function in all three models, even normalizing serum IgE levels in the atopic dermatitis model. Elevations in endogenous GC accounted for these apparent benefits, because coadministration of mifepristone prevented stress-induced disease amelioration. Thus, exogenous stress can benefit rather than aggravate cutaneous inflammatory dermatoses through the anti-inflammatory activity of increased endogenous GC.

Immune Reconstitution Reactions in Human Immunodeficiency Virus–Negative Patients: Report of a Case and Review of the Literature

BACKGROUND Immune reconstitution inflammatory syndrome (IRIS) is a phenomenon initially described in patients with human immunodeficiency virus. Upon initiation of combination antiretroviral therapy, recovery of cellular immunity triggers inflammation to a preexisting infection or antigen that causes paradoxical worsening of clinical disease. A similar phenomenon can occur in human immunodeficiency virus-negative patients, including pregnant women, neutropenic hosts, solid-organ or stem cell transplant recipients, and patients receiving tumor necrosis factor inhibitors. OBSERVATIONS We report a case of leprosy unmasking and downgrading reaction after stem cell transplantation that highlights some of the challenges inherent to the diagnosis of IRIS, especially in patients without human immunodeficiency virus infection, as well as review the spectrum of previously reported cases of IRIS reactions in this population. CONCLUSIONS The mechanism of immune reconstitution reactions is complex and variable, depending on the underlying antigen and the mechanism of immunosuppression or shift in immune status. Use of the term IRIS can aid our recognition of an important phenomenon that occurs in the setting of immunosuppression or shifts in immunity but should not deter us from thinking critically about the distinct processes that underlie this heterogeneous group of conditions.

Epidermal barrier dysfunction in non-atopic HIV: evidence for an "inside-to-outside" pathogenesis.

TO THE EDITOR Xerosis is one of the most common cutaneous manifestations in HIV infection. Although reportedly affecting up to 20–30% of patients with HIV (Rowe et al., 1999; Lee et al., 2007), the underlying cause of this xerosis has not yet been elucidated. In a further subgroup, xerosis is complicated by an atopic dermatitis (AD)-like rash or xerotic eczema. Xerosis is reportedly more common in HIV-infected individuals with CD4 cell counts p200 ml, and treatment with protease inhibitors, such as indinavir, provokes xerosis even in patients with higher CD4 counts (Lee et al., 2007). Impaired epidermal barrier function is now closely linked to the pathogenesis of AD (Palmer et al., 2006; Weidinger et al., 2006; Sandilands et al., 2007), where defective stratum corneum (SC) barrier function in turn predisposes to repeated antigen penetration, leading to Th2-dominant inflammation (Fallon et al., 2009; Scharschmidt et al., 2009). Accordingly, overexpression of the Th2 cytokine (IL-4) in transgenic mice causes spontaneous AD (Lee and Flavell, 2004). But the chronic barrier abnormality in AD also stimulates production of epidermal cytokines and growth factors that stimulate inflammation (‘‘cytokine cascade’’), eventually recruiting Th2 cells, which in turn produce cytokines, such as IL-4, that further compromises barrier function (‘‘outside-inside-back to outside’’) hypothesis (Elias and Steinhoff, 2008; Elias et al., 2008). Although it is widely believed that HIV-associated xerosis and xerotic eczema reflect a worsening of pre-existent AD (Parkin et al., 1987; Cockerell 1991), HIV infection itself provokes a Th2 immunophenotype (Klein et al., 1997), and as noted above, Th2 cytokines themselves downregulate barrier function (Kurahashi et al., 2008), as well as ceramide synthesis (Hatano et al., 2005), and expression of several differentiation-related structural proteins (Howell et al., 2007, 2008). Hence, we hypothesized that a primary, infection-triggered Th2-dominant immune abnormality could drive subsequent epidermal changes in HIV. Accordingly, we assessed here cutaneous permeability barrier status in a cohort of HIVþ subjects, with no previous or current history of either AD or mucosal atopy. These HIVþ , non-atopic patients display abnormal basal barrier function that becomes much more prominent in a subgroup of HIVþ patients with xerotic eczema. Moreover, CD4þ cell nadirs (o150ml) correlated significantly with prominent skin dryness, but in this non-atopic cohort, antiretroviral therapy aggravated neither barrier function, xerosis, nor SC hydration, suggesting that protease inhibitor (PI)-related xerosis and xerotic eczema could occur primarily or only in HIVþ patients with previous or concurrent AD/atopy. We first assessed basal barrier function over non-lesional skin sites in 21 HIVþ patients (age 47±SD 7.4, two female patients) and six age, sex, and pigment-type matched controls (age 45±SD 9.6, one female patient). The mean duration of HIV infection in these subjects was 12.1±SD 6.4 years. A random group of seven HIVþ patients was genotyped for the three most common filaggrin mutations (that is, R501X, 2282del4, and R2447X), and none carried mutations, despite the fact that several of the patients showed abnormal barrier function and clinical xerosis (Supplementary Table 1). Most of our patients were on treatment with anti-retroviral drugs (n1⁄4 17, 81%), including a protease inhibitor (n1⁄413, 62%). Nine patients displayed clinically normal skin, whereas nine others had xerosis, and a further three patients displayed xerosis plus generalized xerotic eczema. HIVþ patients with no signs of eczema displayed abnormal basal barrier function (Figure 1a), including subjects without xerosis (E3fold increase in transepidermal water loss (TEWL) rates (6.4±0.7 vs 2.2±0.3; Po0.001). Finally, even patients who were off antiretroviral treatment displayed elevated TEWL rates, showing that the barrier abnormality in HIVþ patients cannot be ascribed to antiretroviral therapy. The barrier abnormality became much more prominent in a subgroup of three patients with xerotic eczema (10.5±1.1 vs 2.2±0.3, Po0.001), and these patients displayed significantly reduced SC hydration (35.3±3.2 vs 53.2±2.0, P1⁄40.002) and a higher surface pH (6.0±0.6 vs 5.2±0.1, Po0.05), compared with HIV patients without eczema (Figure 2). Finally, SC integrity/ cohesion, surface pH, SC hydration and barrier recovery kinetics did not significantly differ in the HIVþ versus control groups as a whole (Figure 2). We next assessed epidermal function in relation to patients’ historically lowest CD4 counts (CD4 nadir) in these continuously monitored patients. Barrier function was abnormal in HIVþ patients, whether CD4 nadirs were less than or greater than 150ml (data not shown). Similarly, SC integrity/cohesion and barrier recovery rates were comparable in patients with low CD4 nadirs versus nadirs 4150ml (not shown). Although HIV patients with CD4þ nadir o150 ml displayed worse subjectand physician-rated visual dryness Abbreviations: AD, atopic dermatitis; KLK, kallikrein; PI, protease inhibitor; RA, retinoic acid; SC, stratum corneum; TEWL, transepidermal water loss