Netherton syndrome: defective kallikrein inhibition in the skin leads to skin inflammation and allergy

Physiological Effects of Soat1 Inactivation on Homeostasis of the Mouse Ocular Surface

Purpose

Soat1/SOAT1 have been previously reported to be critical for the biosynthesis of cholesteryl esters (CEs) in the mouse Meibomian glands (MGs) as the loss of function led to an arrest of CE production and a substantial accumulation of nonesterified cholesterol in the meibum, causing an increase in its melting temperature. The purpose of this study was to further investigate the role of Soat1 in meibogenesis and ocular surface physiology.

Methods

The mouse ocular features of knockout Soat1-/- and wild type (WT) mice were studied using various ophthalmic and histological techniques, mouse lipidomes were monitored using liquid chromatography/mass spectrometry, whereas their transcriptomes were compared to characterize the effects of the mutation on the gene expression profiles in the MG and cornea.

Results

Soat1-/- mice displayed increased tear production and severe corneal abnormalities, such as corneal thinning, (neo)vascularization, ulceration, and opacification that progressed with aging. Transcriptomic analyses led to identification of a range of significantly disrupted pathways, which included general and specific lipid metabolism-related pathways, keratinization, angiogenesis/(neo)vascularization, muscle contraction, and several other pathways. In addition, histological and histochemical experiments revealed morphological changes in the MG, cornea, and conjunctiva in Soat1-/- mice. Notably, the mRNA microarray expression level of Soat1 in WT MGs (log2 17.5) was 1000 × of that in the mouse cornea (log2 7.5).

Conclusions

These findings suggest a direct involvement of Soat1/SOAT1 in MGs in maintaining ocular surface homeostasis, in general, and corneal health, specifically.

Netherton Syndrome in Thai Children: A Report of Two Cases With a Literature Review

Netherton syndrome (NS) is a severe autosomal recessive disorder characterized by the triad of congenital ichthyosiform erythroderma, trichorrhexis invaginata, and atopic diathesis. We report two cases that experienced severe congenital exfoliative dermatitis, recurrent infections, and allergic conditions. Examinations of hair under the light microscope revealed trichorrhexis invaginata. Whole exome sequencing identified homologous pathogenic mutations of SPINK5. Optimal skincare and proper nutritional support could improve patients' quality of life.

ECRG2/SPINK7 Tumor Suppressor as Modulator of DNA Damage Response

Esophageal Cancer-Related Gene 2 (ECRG2), also known as Serine Peptidase Inhibitor Kazal type 7 (SPINK7), is a novel tumor suppressor gene from the SPINK family of genes that exhibits anticancer potential. ECRG2 was originally identified during efforts to discover genes involved in esophageal tumorigenesis. ECRG2 was one of those genes whose expression was absent or reduced in primary human esophageal cancers. Additionally, absent or reduced ECRG2 expression was also noted in several other types of human malignancies. ECRG2 missense mutations were identified in various primary human cancers. It was reported that a cancer-derived ECRG2 mutant (valine to glutamic acid at position 30) failed to induce cell death and caspase activation triggered by DNA-damaging anticancer drugs. Furthermore, ECRG2 suppressed cancer cell proliferation in cultured cells and grafted tumors in animals and inhibited cancer cell migration/invasion and metastasis. ECRG2 also was identified as a negative regulator of Hu-antigen R (HuR), an oncogenic RNA-binding protein that is known to regulate mRNA stability and the expression of transcripts corresponding to many cancer-related genes. ECRG2 function is important also for the regulation of inflammatory responses and the maintenance of epithelial barrier integrity in the esophagus. More recently, ECRG2 was discovered as one of the newest members of the pro-apoptotic transcriptional targets of p53. Two p53-binding sites (BS-1 and BS-2) were found within the proximal region of the ECRG2 gene promoter; the treatment of DNA-damaging agents in cancer cells significantly increased p53 binding to the ECRG2 promoter and triggered a strong ECRG2 promoter induction following DNA damage. Further, the genetic depletion of ECRG2 expression significantly impeded apoptotic cell death induced by DNA damage and wild-type p53 in cancer cells. These findings suggest that the loss of ECRG2 expression, commonly observed in human cancers, could play important roles in conferring anticancer drug resistance in human cancers. Thus, ECRG2 is a novel regulator in DNA damage-induced cell death that may also be a potential target for anticancer therapeutics.

Mini-PBPK-Based Population Model and Covariate Analysis to Assess the Complex Pharmacokinetics and Pharmacodynamics of RO7449135, an Anti-KLK5/KLK7 Bispecific Antibody in Cynomolgus Monkeys

RO7449135, an anti-kallikrein (KLK)5/KLK7 bispecific antibody, is in development as a potential therapy against Netherton's syndrome (NS). In cynomolgus monkey studies, RO7449135 bound to KLK5 and KLK7, causing considerable accumulation of total KLKs, but with non-dose-proportional increase. To understand the complex PKPD, a population model with covariate analysis was developed accounting for target binding in skin and migration of bound targets from skin to blood. The covariate analysis suggested the animal batch as the categorical covariate impacting the different KLK5 synthesis rates between the repeat-dose study and single-dose study, and the dose as continuous covariate impacting the internalization rate of the binary and ternary complexes containing KLK7. To comprehend the mechanism underlying, we hypothesized that inhibition of KLK5 by RO7449135 prevented its cleavage of the pro-enzyme of KLK7 (pro-KLK7) and altered the proportion between pro-KLK7 and KLK7. Besides the pro-KLK7, RO7449135 can interact with other proteins like LEKTI through KLK7 connection in a dose-dependent manner. The different high-order complexes formed by RO7449135 interacting with pro-KLK7 or LEKTI-like proteins can be subject to faster internalization rate. Accounting for the dose and animal batch as covariates, the model-predicted free target suppression is well aligned with the visual target engagement check. The population PKPD model with covariate analysis provides the scientific input for the complex PKPD analysis, successfully predicts the target suppression in cynomolgus monkeys, and thereby can be used for the human dose projection of RO7449135.

Dupilumab in the treatment of genodermatosis: A systematic review

Dupilumab interferes with the signaling pathways of IL-4 and IL-13 and is effective in treating atopic dermatitis. Specific genodermatoses, including Netherton syndrome, epidermolysis bullosa pruriginosa, and hyper-IgE syndrome, are Th2 skewed diseases with activation of type 2 inflammation. We performed this systematic review to investigate the therapeutic role of dupilumab in the treatment of genodermatosis. A systematic search was conducted of the PubMed, Embase, Web of Science, and Cochrane databases from inception to December 13, 2021. The review included studies with relevant terms including "dupilumab," "genodermatosis", "Netherton syndrome", "ichthyosis", "epidermolysis bullosa" and "hyper-IgE syndrome". The initial search yielded 2,888 results, of which 28 studies and 37 patients with genodermatosis were enrolled. The assessed genodermatoses included Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with genetic disorders. Most of the reported cases showed significant clinical improvement after the initiation of dupilumab treatment without major adverse events. Decreased immunoglobulin E levels and cytokine normalization have also been documented. In conclusion, Dupilumab may have a potential therapeutic role in certain genodermatoses skewed towards T helper 2 (Th2) immunity, including Netherton syndrome, epidermolysis bullosa pruriginosa, hyper-IgE syndrome, Hailey-Hailey disease, and severe eczema associated with some genetic disorders.

Prevalence of and risk factors for nutritional deficiency and food allergy in a cohort of 21 patients with Netherton syndrome

BACKGROUND

Netherton syndrome (NS; OMIM: 256500) is a rare autosomal recessively inherited disease due to SPINK5 mutations. Hair and inflammatory skin involvement are variable along with allergies. Morbidity and mortality are high, particularly in infancy. A detailed clinical analysis of a NS patient cohort should broaden the understanding of nutritional challenges and allergic comorbidities.

METHODS

In this retrospective monocentric cohort study, medical and dietetic records of pediatric NS patients, presenting between 1999 and 2018, were reviewed. The severity of skin involvement was assessed according to the extent of the body surface area (BSA) affected by erythema.

RESULTS

We identified 21 patients with NS (median age 11.6 years). Within the first 6 months of life, requirements for fluid and kcals/protein were high for all patients (average 228 ml/kg/day) and infants had an average of 1.9 feed changes (range 0-4) due to food intolerance. Clinical evidence for IgE-mediated food allergy was present in 84.2% (16/19 children, 2 no data) with a range of 1-12 food allergies per patient. In 75%, more than one food had to be avoided. Specific IgE levels were falsely positive in 38.3% and 8/18 patients (44.4%). One-third (5/15; 6 no data) of patients, all with severe disease, had anaphylactic reactions following ingestion of fish (n = 2), sesame (n = 1), cow's milk (n = 1), and both peanut and egg (n = 1).

CONCLUSIONS

Our data emphasize feeding difficulties in children with NS and reveal an unexpectedly higher prevalence of food allergies that gives evidence to the importance of early coordinated multidisciplinary care for overcoming these challenges in NS.

Eosinophilic esophagitis: Immune mechanisms and therapeutic targets

Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease of the oesophagus and is clinically characterized by upper gastrointestinal (GI) symptoms including dysphagia and esophageal food impaction. Histopathologic manifestations, which include intraepithelial eosinophilic inflammation and alterations of the esophageal squamous epithelium, such as basal zone hyperplasia (BZH) and dilated intercellular spaces (DIS), are thought to contribute to esophageal dysfunction and disease symptoms. Corroborative clinical and discovery science-based studies have established that EoE is characterized by an underlying allergic inflammatory response, in part, related to the IL-13/CCL26/eosinophil axis driving dysregulation of several key epithelial barrier and proliferative regulatory genes including kallikrein (KLK) serine proteases, calpain 14 (CAPN14) and anoctamin 1 (ANO1). The contribution of these inflammatory and proliferative processes to the clinical and histological manifestations of disease are not fully elucidated. Herein, we discuss the immune molecules and cells that are thought to underlie the clinical and pathologic manifestations of EoE and the emerging therapeutics targeting these processes for the treatment of EoE.

Cell death in skin function, inflammation, and disease

Cell death is an essential process that plays a vital role in restoring and maintaining skin homeostasis. It supports recovery from acute injury and infection and regulates barrier function and immunity. Cell death can also provoke inflammatory responses. Loss of cell membrane integrity with lytic forms of cell death can incite inflammation due to the uncontrolled release of cell contents. Excessive or poorly regulated cell death is increasingly recognised as contributing to cutaneous inflammation. Therefore, drugs that inhibit cell death could be used therapeutically to treat certain inflammatory skin diseases. Programmes to develop such inhibitors are already underway. In this review, we outline the mechanisms of skin-associated cell death programmes; apoptosis, necroptosis, pyroptosis, NETosis, and the epidermal terminal differentiation programme, cornification. We discuss the evidence for their role in skin inflammation and disease and discuss therapeutic opportunities for targeting the cell death machinery.

Revisiting the Roles of Filaggrin in Atopic Dermatitis

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

Netherton syndrome subtypes share IL-17/IL-36 signature with distinct IFN-α and allergic responses

BACKGROUND

Netherton syndrome (NS) is a rare recessive skin disorder caused by loss-of-function mutations in SPINK5 encoding the protease inhibitor LEKTI (lymphoepithelial Kazal-type-related inhibitor). NS patients experience severe skin barrier defects, display inflammatory skin lesions, and have superficial scaling with atopic manifestations. They present with typical ichthyosis linearis circumflexa (NS-ILC) or scaly erythroderma (NS-SE).

OBJECTIVE

We used a combination of several molecular profiling methods to comprehensively characterize the skin, immune cells, and allergic phenotypes of NS-ILC and NS-SE patients.

METHODS

We studied a cohort of 13 patients comprising 9 NS-ILC and 4 NS-SE.

RESULTS

Integrated multiomics revealed abnormal epidermal proliferation and differentiation and IL-17/IL-36 signatures in lesion skin and in blood in both NS endotypes. Although the molecular profiles of NS-ILC and NS-SE lesion skin were very similar, nonlesion skin of each disease subtype displayed distinctive molecular features. Nonlesion and lesion NS-SE epidermis showed activation of the type I IFN signaling pathway, while lesion NS-ILC skin differed from nonlesion NS-ILC skin by increased complement activation and neutrophil infiltration. Serum cytokine profiling and immunophenotyping of circulating lymphocytes showed a T_H2-driven allergic response in NS-ILC, whereas NS-SE patients displayed mainly a T_H9 axis with increased CCL22/MDC and CCL17/TARC serum levels.

CONCLUSIONS

This study confirms IL-17/IL-36 as the predominant signaling axes in both NS endotypes and unveils molecular features distinguishing NS-ILC and NS-SE. These results identify new therapeutic targets and could pave the way for precision medicine of NS.

Defining the Protease and Protease Inhibitor (P/PI) Proteomes of Healthy and Diseased Human Skin by Modified Systematic Review

Proteases and protease inhibitors (P/PIs) are involved in many biological processes in human skin, yet often only specific families or related groups of P/PIs are investigated. Proteomics approaches, such as mass spectrometry, can define proteome signatures (including P/PIs) in tissues; however, they struggle to detect low-abundance proteins. To overcome these issues, we aimed to produce a comprehensive proteome of all P/PIs present in normal and diseased human skin, in vivo, by carrying out a modified systematic review using a list of P/PIs from MEROPS and combining this with key search terms in Web of Science. Resulting articles were manually reviewed against inclusion/exclusion criteria and a dataset constructed. This study identified 111 proteases and 77 protease inhibitors in human skin, comprising the serine, metallo-, cysteine and aspartic acid catalytic families of proteases. P/PIs showing no evidence of catalytic activity or protease inhibition, were designated non-peptidase homologs (NPH), and no reported protease inhibitory activity (NRPIA), respectively. MMP9 and TIMP1 were the most frequently published P/PIs and were reported in normal skin and most skin disease groups. Normal skin and diseased skin showed significant overlap with respect to P/PI profile; however, MMP23 was identified in several skin disease groups, but was absent in normal skin. The catalytic profile of P/PIs in wounds, scars and solar elastosis was distinct from normal skin, suggesting that a different group of P/PIs is responsible for disease progression. In conclusion, this study uses a novel approach to provide a comprehensive inventory of P/PIs in normal and diseased human skin reported in our database. The database may be used to determine either which P/PIs are present in specific diseases or which diseases individual P/PIs may influence.

A Novel SPINK5 Gene Mutation Associated with Netherton Syndrome in an Omani Patient

Netherton syndrome (NS) is an autosomal recessive primary immunodeficiency. It is characterised by substantial skin barrier defects and is often misdiagnosed as severe atopic dermatitis or hyper-immunoglobulin E syndrome. Although more than 80 NS-associated pathogenic mutations in the serine peptidase inhibitor kazal type 5 (SPINK5) gene have been reported worldwide, only one has been reported in the Arab population to date. We report the case of a novel association between the c.1887+1G>A mutation in the SPINK5 gene and NS in an Omani-Arab patient born in 2014 who was managed at a paediatric immunology clinic in Muscat, Oman. Accurate genetic diagnosis facilitated tailored clinical management of the index patient and enabled the provision of genetic counselling and offering of future reproductive options to the individuals related to the index patient.

A KLK4 proteinase substrate capture approach to antagonize PAR1

Proteinase-activated receptor-1 (PAR1), triggered by thrombin and other serine proteinases such as tissue kallikrein-4 (KLK4), is a key driver of inflammation, tumor invasiveness and tumor metastasis. The PAR1 transmembrane G-protein-coupled receptor therefore represents an attractive target for therapeutic inhibitors. We thus used a computational design to develop a new PAR1 antagonist, namely, a catalytically inactive human KLK4 that acts as a proteinase substrate-capture reagent, preventing receptor cleavage (and hence activation) by binding to and occluding the extracellular R41-S42 canonical PAR1 proteolytic activation site. On the basis of in silico site-saturation mutagenesis, we then generated KLK4S207A,L185D, a first-of-a-kind 'decoy' PAR1 inhibitor, by mutating the S207A and L185D residues in wild-type KLK4, which strongly binds to PAR1. KLK4S207A,L185D markedly inhibited PAR1 cleavage, and PAR1-mediated MAPK/ERK activation as well as the migration and invasiveness of melanoma cells. This 'substrate-capturing' KLK4 variant, engineered to bind to PAR1, illustrates proof of principle for the utility of a KLK4 'proteinase substrate capture' approach to regulate proteinase-mediated PAR1 signaling.

Functional role of kallikrein 5 and proteinase-activated receptor 2 in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic, food antigen-driven, inflammatory disease of the esophagus and is associated with impaired barrier function. Evidence is emerging that loss of esophageal expression of the serine peptidase inhibitor, kazal type 7 (SPINK7), is an upstream event in EoE pathogenesis. Here, we provide evidence that loss of SPINK7 mediates its pro-EoE effects via kallikrein 5 (KLK5) and its substrate, protease-activated receptor 2 (PAR2). Overexpression of KLK5 in differentiated esophageal epithelial cells recapitulated the effect of SPINK7 gene silencing, including barrier impairment and loss of desmoglein-1 expression. Conversely, KLK5 deficiency attenuated allergen-induced esophageal protease activity, modified commensal microbiome composition, and attenuated eosinophilia in a murine model of EoE. Inhibition of PAR2 blunted the cytokine production associated with loss of SPINK7 in epithelial cells and attenuated the allergen-induced esophageal eosinophilia in vivo. Clinical samples substantiated dysregulated PAR2 expression in the esophagus of patients with EoE, and delivery of the clinically approved drug α1 antitrypsin (A1AT, a protease inhibitor) inhibited experimental EoE. These findings demonstrate a role for the balance between KLK5 and protease inhibitors in the esophagus and highlight EoE as a protease-mediated disease. We suggest that antagonizing KLK5 and/or PAR2 has potential to be therapeutic for EoE.

The molecular mechanisms underlying acrosome biogenesis elucidated by gene-manipulated mice

Sexual reproduction requires the fusion of two gametes in a multistep and multifactorial process termed fertilization. One of the main steps that ensures successful fertilization is acrosome reaction. The acrosome, a special kind of organelle with a cap-like structure that covers the anterior portion of sperm head, plays a key role in the process. Acrosome biogenesis begins with the initial stage of spermatid development, and it is typically divided into four successive phases: the Golgi phase, cap phase, acrosome phase, and maturation phase. The run smoothly of above processes needs an active and specific coordination between the all kinds of organelles (endoplasmic reticulum, trans-golgi network and nucleus) and cytoplasmic structures (acroplaxome and manchette). During the past two decades, an increasingly genes have been discovered to be involved in modulating acrosome formation. Most of these proteins interact with each other and show a complicated molecular regulatory mechanism to facilitate the occurrence of this event. This Review focuses on the progresses of studying acrosome biogenesis using gene-manipulated mice and highlights an emerging molecular basis of mammalian acrosome formation.

Secukinumab Therapy for Netherton Syndrome

Importance

Netherton syndrome (NS) is a rare, severe genetic disorder of cornification with high morbidity. Treatment for NS has been notoriously difficult. Recent studies showed an upregulated helper T cell (TH) 17/interleukin 23 (IL-23) pathway in NS, suggesting the possibility of treatment strategies that target IL-17.

Objective

To evaluate the clinical response of NS to treatment with the IL-17 antagonist secukinumab.

Design, Setting, and Participants

This case series study reports the experience of compassionate use therapy with secukinumab in 4 patients with severe NS, including 2 children, from December 1, 2018, to December 1, 2019, with 3 patients still undergoing treatment at the time of final analysis. Data were analyzed from December 1, 2018, to December 1, 2019.

Main Outcomes and Measures

Expression of IL-17 in the skin was evaluated by immunohistochemical analysis, and serum cytokine concentrations were measured using a commercially available assay. Treatment response was assessed using the Ichthyosis Area and Severity Index (IASI) total score, including measures of erythema and scaling, the Dermatology Life Quality Index (DLQI), and the 5-D itch scale.

Results

In all 4 patients (age range, 9-27 years; 3 male and 1 female), immunostaining with an IL-17A antibody showed an increased number of positive cells in lesional skin. Cytokine assessment in serum samples revealed increased levels of CCL20. Treatment duration with secukinumab was 3 to 12 months at the time of this report. After 3 months of therapy, IASI scores were reduced by 44% to 88%, DLQI scores were reduced by 40% to 76%, and 5-D itch scale scores were reduced by 27% to 62%. This outcome was sustained at the 6-month follow-up. Two patients with an erythrodermic phenotype showed marked improvement of all parameters. A refractory palmoplantar eczematous eruption occurred in 2 patients, and a candidal nail infection developed in 2 patients. No severe adverse events were reported.

Conclusions and Relevance

This initial case series reporting the use of anti-IL-17 therapy in NS demonstrated marked cutaneous improvement, particularly in 2 pediatric patients with erythrodermic phenotypes. Further studies are needed to evaluate the long-term benefit of this potential treatment modality.

Establishment of an induced pluripotent stem cell line (SAHGMUi001-A) from a patient with Netherton syndrome carrying SPINK5 mutation

Netherton syndrome (NS) is a rare, autosomal recessive hereditary skin disease caused by mutations in SPINK5 gene, characterized with severe skin barrier damage. A human induced pluripotent stem cell (iPSC) line has been established with electroporation method from urine-derived cells of a NS patient carrying a compound heterozygous mutation c.2260A > T (p.K754X) and c.2423C > T(p.T808I) in SPINK5 gene. This iPSC line may serve as a valuable model for the research of pathogenesis of NS, and the mechanisms and therapeutics for skin barrier damage.

Initial Evidence of Distinguishable Bacterial and Fungal Dysbiosis in the Skin of Patients with Atopic Dermatitis or Netherton Syndrome

Atopic dermatitis (AD) is an inflammatory skin disease in which epidermal barrier impairment, often owing to FLG null mutations, precedes immune hyperresponsiveness. Ichthyosis vulgaris is characterized by FLG null mutations and noninflamed dry skin. Netherton syndrome (NS), caused by SPINK5 null mutations, is characterized by generalized erythroderma with scaling and atopic manifestations. The goal of this work was to evaluate associations between specific skin disease features, such as ichthyotic and/or atopic manifestations, and the skin bacterial and fungal microbiota. Taxon diversity showed greater variation in the bacterial microbiota than in the fungal microbiota in the skin diseases. The relative abundances of Firmicutes (Staphylococcus) and Actinobacteria (Corynebacterium) were augmented in ichthyosis vulgaris, AD, and NS, whereas those of Proteobacteria/Enhydrobacter and Bacteroidetes were reduced, regardless of body site. Furthermore, proportions of Staphylococcus were correlated with transepidermal water loss and serum IgE levels. Nevertheless, the skin of patients with low to mild AD was overcolonized with Staphylococcus epidermidis and not with Staphylococcus aureus. Ascomycota were increased in both AD and NS, but from expansion of different fungal species. Finally, the expansion of pathologic bacteria in AD and NS might be supported by surrounding fungi. Thus, distinguishable bacterial and fungal skin dysbiosis in AD, NS, and ichthyosis vulgaris emphasizes disease-specific pathomechanisms.

Netherton Syndrome: Insights into Pathogenesis and Clinical Implications

Netherton syndrome (NS) is a rare skin disorder involving the skin, hair, and immune system. Pathological manifestations are due to unopposed kallikrein peptidase activity because of a SPINK5 gene deficiency. In their article, Gouin et al. explore the role of kallikrein 14 in the stratum granulosum, defining it as an important player implicated in the pathogenesis of NS hair shaft anomalies.

Netherton syndrome: Temporary response to dupilumab

Netherton syndrome (NS) is an orphan disease characterized by congenital ichthyosis, hair abnormalities, and atopy, with limited treatment options. We achieved temporary improvement only during the initial 6 weeks of treatment with dupilumab, which differs from the sustained improvement observed in 2 other recently published cases. Although the clinical presentation of atopy and increased pre-allergic cytokines in NS patients suggest that dupilumab may be beneficial, larger studies are required.

Cytokinocytes: the diverse contribution of keratinocytes to immune responses in skin

The skin serves as the primary interface between our body and the external environment and acts as a barrier against entry of physical agents, chemicals, and microbes. Keratinocytes make up the main cellular constitute of the outermost layer of the skin, contributing to the formation of the epidermis, and they are crucial for maintaining the integrity of this barrier. Beyond serving as a physical barrier component, keratinocytes actively participate in maintaining tissue homeostasis, shaping, amplifying, and regulating immune responses in skin. Keratinocytes act as sentinels, continuously monitoring changes in the environment, and, through microbial sensing, stretch, or other physical stimuli, can initiate a broad range of inflammatory responses via secretion of various cytokines, chemokines, and growth factors. This diverse function of keratinocytes contributes to the highly variable clinical manifestation of skin immune responses. In this Review, we highlight the highly diverse functions of epidermal keratinocytes and their contribution to various immune-mediated skin diseases.

The Skin as a Window into Primary Immune Deficiency Diseases: Atopic Dermatitis and Chronic Mucocutaneous Candidiasis

Primary immune deficiency diseases characteristically present with recurrent, severe, or unusual infections. These infections may often involve the skin, with mucocutaneous candidal infections seen in a variety of different primary immune deficiencies. Primary immune deficiencies may also present with noninfectious cutaneous complications, of which eczema is the most common. In a patient with suspected primary immune deficiency, the presence of eczema or candidal skin infections offers critical information about the underlying immune defect, either the presence of atopy or defect in the T_H17 pathway, respectively. These skin manifestations also are often early or heralding findings of the underlying immunologic disease. Therefore, awareness of associations between these skin findings and specific immune deficiencies may aide in the early detection and treatment of serious or life-threatening immunologic defects. This review specifically will focus on the primary immune deficiencies commonly associated with eczema or mucocutaneous candidiasis.

The role of kallikreins in inflammatory skin disorders and their potential as therapeutic targets

The skin is a vital organ of the human body, serving numerous protective and functional roles that are essential for survival. Residing in the epidermis are various epidermal proteases responsible for the establishment and regulation of barrier function. The human tissue kallikrein-related peptidase family conserves homeostasis of the skin barrier through their roles in desquamation, antimicrobial defense, innate immune response, and barrier maintenance. The activity of kallikreins is tightly regulated and dysregulation of kallikrein activity is seen to contribute to the formation of several inflammatory skin disorders. This review highlights the roles of kallikreins in skin homeostasis and pathologies. Due to their part in these skin disorders, inhibitors of the skin kallikreins have become attractive therapeutics. Over the past few years, both natural and synthetic inhibitors of several kallikreins have been identified and are undergoing further development as treatments to restore compromised barrier function. This review summarizes the kallikrein inhibitors under development for this purpose. These inhibitors remain promising therapeutics in cases of severe skin inflammation not well managed by current therapies.

Skin barrier lipid enzyme activity in Netherton patients is associated with protease activity and ceramide abnormalities

Individuals with Netherton syndrome (NTS) have increased serine protease activity, which strongly impacts the barrier function of the skin epidermis and leads to skin inflammation. Here, we investigated how serine protease activity in NTS correlates with changes in the stratum corneum (SC) ceramides, which are crucial components of the skin barrier. We examined two key enzymes involved in epidermal ceramide biosynthesis, β-glucocerebrosidase (GBA) and acid-sphingomyelinase (ASM). We compared in situ expression levels and activities of GBA and ASM between NTS patients and controls and correlated the expression and activities with i) SC ceramide profiles, ii) in situ serine protease activity, and iii) clinical presentation of patients. Using activity-based probe labeling, we visualized and localized active epidermal GBA, and a newly developed in situ zymography method enabled us to visualize and localize active ASM. Reduction in active GBA in NTS patients coincided with increased ASM activity, particularly in areas with increased serine protease activity. NTS patients with scaly erythroderma exhibited more pronounced anomalies in GBA and ASM activities than patients with ichthyosis linearis circumflexa. They also displayed a stronger increase in SC ceramides processed via ASM. We conclude that changes in the localization of active GBA and ASM correlate with i) altered SC ceramide composition in NTS patients, ii) local serine protease activity, and iii) the clinical manifestation of NTS.

Recent advances in potential targets for eosinophilic esophagitis treatments

Introduction: Diagnostic and therapeutic strategies in eosinophilic esophagitis (EoE) are constantly evolving. Recently, the improved understanding of EoE pathogenesis has led to identification of a variety of other potential targets that have never been considered before.Areas covered: In September 2019, we performed structured literature searches in Medline and PubMed, Cochrane meta-analyses, and abstracts of international congresses to review new potential therapeutic approaches for EoE.Expert opinion: The advent of omics disciplines has been helping in finding new molecular targets in EoE pathogenesis and may provide future guidance for deep phenotyping of the disease and therefore facilitate the possibility of personalized medicine. Interestingly, these new treatments should be focused on the restoration of epithelial barrier dysfunction, downregulation of specific molecular pathways of eosinophilic inflammation, and finally, prevention of esophageal remodeling. In this review, we highlight the most recent insights in EoE pathogenesis, which open new pathways for developing new therapeutic targets for clinical practice.

Hair abnormality in Netherton syndrome observed under polarized light microscopy

BACKGROUND

Trichorrhexis invaginata, the main diagnostic feature of Netherton syndrome, is often difficult to detect, especially in adult patients.

OBJECTIVE

We sought to describe a characteristic feature of hairs in Netherton syndrome using a polarized light microscope and the underlying histopathologic changes.

METHODS

Hairs obtained from 8 patients with Netherton syndrome were observed under polarized light, and we evaluated the correlation between number of band-like patterns and disease severity.

RESULTS

Under polarized microscopy, the hair shafts of 8 patients showed a characteristic band-like pattern under polarized light that was not observed in healthy control individuals or patients with atopic dermatitis. This discontinuity of polarized light shows a band-like pattern in which the bands mostly ranged from 0.1 to 1.0 mm in width. The observed ratio of this finding was significantly higher than that of trichorrhexis invaginata observed under light microscopy, and patients with severe dermatitis tended to have a higher ratio than those with less severe dermatitis.

LIMITATIONS

Comparative examination among other congenital ichthyoses was not performed.

CONCLUSIONS

A band-like pattern in hairs with polarized light microscopy can be seen in Netherton syndrome and may have potential utility as a diagnostic marker.

[Fatal outcome of Netherton syndrome due to excessive use of topical corticosteroids in an adult patient]

INTRODUCTION

Netherton syndrome (NS) is a rare disease caused by SPINK5 mutations associated with ichthyosis (erythroderma and desquamation), alopecia and atopic manifestations. There are no effective treatments. Topical corticosteroids may be used for a limited period in the event of eczema. Herein we report on a patient with fatal complications related to misuse of topical corticosteroids.

PATIENTS AND METHODS

A 38-year-old woman with NS had been using betamethasone for about ten years for severe pruritus. Consumption was estimated at 7.2kg per year. On examination, she had osteoporosis, Cushing's syndrome, corticotropic insufficiency and inframammary, axillary, and intergluteal superinfected intertrigo. During hospitalization for necrotic leg wounds on severe skin atrophy, she sustained a fracture on falling down. The course was marked by the onset of septic shock of unknown etiology, complicated by acute adrenal insufficiency leading to fatal multi-organ failure.

DISCUSSION

Many iatrogenic cases related to topical corticosteroids in children have been reported in the literature, including one case of fatal outcome (CMV infection) in an infant. Such iatrogenic cases are rarer in adults and we observed no fatal cases. In NS, the adverse effects of topical corticosteroids are amplified due to the major defect in the skin barrier which enhances the systemic passage of these drugs. In the absence of any effective therapeutic alternative, weaning patients off topical corticosteroids is usually difficult.

CONCLUSION

This case illustrates the severity of iatrogenic effects secondary to misuse of topical corticosteroids in NS as well as the need to find effective new treatments for this syndrome.

Control of cell death-associated danger signals during cornification prevents autoinflammation of the skin

The function of the skin as a barrier to the environment is mainly achieved by the outermost layers of the epidermis. In the granular layer, epidermal keratinocytes undergo the last steps of their terminal differentiation program resulting in cornification. The coordinated conversion of living keratinocytes into corneocytes, the building blocks of the cornified layer, represents a unique form of programmed cell death. Recent studies have identified numerous genes that are specifically expressed in terminally differentiated keratinocytes and, surprisingly, this genetic program does not only include mediators of cornification but also suppressors of pyroptosis, another mode of programmed cell death. Pyroptosis is activated by inflammasomes, leads to the release of interleukin-1 (IL-1) family cytokines, and thereby activates inflammation. In addition, inhibitors of potentially pro-inflammatory proteases and enzymes removing danger-associated cytoplasmic DNA are expressed in differentiated keratinocytes. We propose the concept of cornification as an inherently hazardous process in which damaging side effects are actively suppressed by protective mechanisms. In support of this hypothesis, loss-of-function mutations in epidermal protease inhibitors and IL-1 family antagonists suffice to induce autoinflammation. Similarly, exogenous disturbances of either cornification or its accompanying control mechanisms may be starting points for skin inflammation. Further studies into the relationship between cornification, pyroptosis and other forms of cell death will help to define the initiation phase of inflammatory skin diseases and offer new targets for disease prevention and therapy.

Mechanisms of gastrointestinal allergic disorders

Gastrointestinal (GI) allergic disease is an umbrella term used to describe a variety of adverse, food antigen-driven, immune-mediated diseases. Although these diseases vary mechanistically, common elements include a breakdown of immunologic tolerance, a biased type 2 immune response, and an impaired mucosal barrier. These pathways are influenced by diverse factors such as diet, infections, exposure to antibiotics and chemicals, GI microbiome composition, and genetic and epigenetic elements. Early childhood has emerged as a critical period when these factors have a dramatic impact on shaping the immune system and therefore triggering or protecting against the onset of GI allergic diseases. In this Review, we will discuss the latest findings on the molecular and cellular mechanisms that govern GI allergic diseases and how these findings have set the stage for emerging preventative and treatment strategies.

Loss of kallikrein-related peptidase 7 exacerbates amyloid pathology in Alzheimer's disease model mice

Deposition of amyloid‐β (Aβ) as senile plaques is one of the pathological hallmarks in the brains of Alzheimer's disease (AD) patients. In addition, glial activation has been found in AD brains, although the precise pathological role of astrocytes remains unclear. Here, we identified kallikrein‐related peptidase 7 (KLK7) as an astrocyte‐derived Aβ degrading enzyme. Expression of KLK7 mRNA was significantly decreased in the brains of AD patients. Ablation of Klk7 exacerbated the thioflavin S‐positive Aβ pathology in AD model mice. The expression of Klk7 was upregulated by Aβ treatment in the primary astrocyte, suggesting that Klk7 is homeostatically modulated by Aβ‐induced responses. Finally, we found that the Food and Drug Administration‐approved anti‐dementia drug memantine can increase the expression of Klk7 and Aβ degradation activity specifically in the astrocytes. These data suggest that KLK7 is an important enzyme in the degradation and clearance of deposited Aβ species by astrocytes involved in the pathogenesis of AD.

Kallikrein 5 inhibitors identified through structure based drug design in search for a treatment for Netherton Syndrome

Netherton syndrome (NS) is a rare and debilitating severe autosomal recessive genetic skin disease with high mortality rates particularly in neonates. NS is caused by loss-of-function SPINK5 mutations leading to unregulated kallikrein 5 (KLK5) and kallikrein 7 (KLK7) activity. Furthermore, KLK5 inhibition has been proposed as a potential therapeutic treatment for NS. Identification of potent and selective KLK5 inhibitors would enable further exploration of the disease biology and could ultimately lead to a treatment for NS. This publication describes how fragmentation of known trypsin-like serine protease (TLSP) inhibitors resulted in the identification of a series of phenolic amidine-based KLK5 inhibitors 1. X-ray crystallography was used to find alternatives to the phenol interaction leading to identification of carbonyl analogues such as lactam 13 and benzimidazole 15. These reversible inhibitors, with selectivity over KLK1 (10-100 fold), provided novel starting points for the guided growth towards suitable tool molecules for the exploration of KLK5 biology.

Cross-sectional survey on disease severity in Japanese patients with harlequin ichthyosis/ichthyosis: Syndromic forms and quality-of-life analysis in a subgroup

BACKGROUND

Congenital ichthyoses (CIs) adversely affect quality of life (QOL) in patients. However, the effects of CIs on patient QOL have not been studied sufficiently.

OBJECTIVE

To investigate the association between disease severity and QOL in patients with harlequin ichthyosis (HI) and ichthyosis: syndromic forms (ISFs) METHODS: Clinical information of patients with HI and ISFs from 2010 to 2015 were obtained from 100 dermatology departments/divisions of principal institutes/hospitals throughout Japan. We examined the relationship between disease severity and QOL in patients with HI and ISFs. Patients who were aged 8 years or older and participated in a multicenter retrospective questionnaire survey in Japan were assessed by dermatology life quality index (DLQI, range of 0-30) and clinical ichthyosis score (range of 0-100).

RESULTS

Netherton syndrome patients had a significantly higher risk of allergy to food or environmental allergens than patients with other phenotypes. Keratitis-ichthyosis-deafness (KID) syndrome patients showed a significantly higher risk of skin infections than patients with other phenotypes. Complete data on DLQI were obtained from 13 patients, whose median age was 21 (8-71) years. Nine patients were male, and 4 were female. Systemic retinoids were administrated to 2 of the 3 HI patients. The Spearman's correlation coefficient between the clinical ichthyosis score and DLQI was 0.611 (P < 0.05).

CONCLUSION

We confirmed that Netherton syndrome and KID syndrome patients have a higher risk of allergy to food or environmental allergens and of skin infections, respectively. QOL impairment correlates with disease severity in HI and ISFs patients.

Netherton syndrome; neuropsychological and psychosocial functioning of child and adult patients and their parents

Background:

Netherton syndrome is a rare severe skin disease. Clinical experience showed considerable psychosocial burdens among Netherton syndrome patients/families. Their (neuro)psychological functioning has never been investigated.

Objective:

To investigate neuropsychological/psychosocial functioning of Netherton syndrome patients and parents.

Methods:

A total of 12 Netherton syndrome patients and/or parents completed neuropsychological tests, semi-structured-interviews, and psychological-questionnaires.

Results:

Intelligence results showed disharmonic profiles, with below-average scores on processing speed. Neuropsychological problems and unfavorable outcomes on health-related quality of life, illness-appearance-related problems, and negative social consequences among patients/parents were found. Psychopathological (emotional) problems were reported; stigmatization, bullying was common among Netherton syndrome patients.

Conclusion:

Compared with normative data, Netherton syndrome patients showed neuropsychological and psychosocial problems. Standard follow-up is necessary to identify problems at early stage.

Human hyper-IgE syndrome: singular or plural?

Spectacular progress has been made in the characterization of human hyper-IgE syndrome (HIES) over the last 50 years. HIES is a primary immunodeficiency defined as an association of atopy in a context of very high serum IgE levels, characteristic bacterial and fungal diseases, low-level clinical and biological inflammation, and various non-hematopoietic developmental manifestations. Somewhat arbitrarily, three disorders were successively put forward as the underlying cause of HIES: autosomal dominant (AD) STAT3 deficiency, the only disorder corresponding to the original definition of HIES, and autosomal recessive (AR) DOCK8 and PGM3 deficiencies, in which atopy and high serum IgE levels occur in a context of manifestations not seen in patients with typical HIES. Indeed, these three disorders disrupt different molecular pathways, affect different cell types, and underlie different clinical phenotypes. Surprisingly, several other inherited inborn errors of immunity in which serum IgE levels are high, sometimes almost as high as those in HIES patients, are not considered to belong to the HIES group of diseases. Studies of HIES have been further complicated by the lack of a high serum IgE phenotype in all mouse models of the disease other than two Stat3 mutant strains. The study of infections in mutant mice has helped elucidate only some forms of HIES and infection. Mouse models of these conditions have also been used to study non-hematopoietic phenotypes for STAT3 deficiency, tissue-specific immunity for DOCK8 deficiency, and cell lineage maturation for PGM3 deficiency. We review here the history of the field of HIES since the first clinical description of this condition in 1966, together with the three disorders commonly referred to as HIES, focusing, in particular, on their mouse models. We propose the restriction of the term "HIES" to patients with an AD STAT3-deficiency phenotype, including the most recently described AR ZNF341 deficiency, thus excluding AR DOCK8 and PGM3 deficiencies from the definition of this disease.

SPINK2 deficiency causes infertility by inducing sperm defects in heterozygotes and azoospermia in homozygotes

Azoospermia, characterized by the absence of spermatozoa in the ejaculate, is a common cause of male infertility with a poorly characterized etiology. Exome sequencing analysis of two azoospermic brothers allowed the identification of a homozygous splice mutation in SPINK2, encoding a serine protease inhibitor believed to target acrosin, the main sperm acrosomal protease. In accord with these findings, we observed that homozygous Spink2 KO male mice had azoospermia. Moreover, despite normal fertility, heterozygous male mice had a high rate of morphologically abnormal spermatozoa and a reduced sperm motility. Further analysis demonstrated that in the absence of Spink2, protease-induced stress initiates Golgi fragmentation and prevents acrosome biogenesis leading to spermatid differentiation arrest. We also observed a deleterious effect of acrosin overexpression in HEK cells, effect that was alleviated by SPINK2 coexpression confirming its role as acrosin inhibitor. These results demonstrate that SPINK2 is necessary to neutralize proteases during their cellular transit toward the acrosome and that its deficiency induces a pathological continuum ranging from oligoasthenoteratozoospermia in heterozygotes to azoospermia in homozygotes.

Serine protease inhibitors to treat inflammation: a patent review (2011-2016)

INTRODUCTION

Inflammation is a physiological part of the complex biological response of tissues to counteract various harmful signals. This process involves diverse actors such as immune cells, blood vessels, and nerves as sources of mediators for inflammation control. Among them serine proteases are key elements in both physiological and pathological inflammation.

AREAS COVERED

Serine protease inhibitors to treat inflammatory diseases are being actively investigated by various industrial and academic institutions. The present review covers patent literature on serine protease inhibitors for the therapy of inflammatory diseases patented between 2011 and 2016.

EXPERT OPINION

Serine proteases regulating inflammation are versatile enzymes, usually involved in proinflammatory cytokine production and activation of immune cells. Their dysregulation during inflammation can have devastating consequences, promoting various diseases including skin and lung inflammation, neuroinflammation, and inflammatory arthritis. Several serine proteases were selected for their contribution to inflammatory diseases and significant efforts that are spread to develop inhibitors. Strategies developed for inhibitor identification consist on either peptide-based inhibitor derived from endogenous protein inhibitors or small-organic molecules. It is also worth noting that among the recent patents on serine protease inhibitors related to inflammation a significant number are related to retinal vascular dysfunction and skin diseases.

Atopic dermatitis and the metabolic syndrome

Atopic dermatitis is a common chronic inflammatory skin disease affecting about 10% to 20% of the general population. Disturbances in lipid metabolism contribute to defective lipid lamellae of the stratum corneum. The relationship of the metabolic syndrome and atopic dermatitis, on the contrary, remains unclear, because there are contradictory results from various trials.

TSLP-activated dendritic cells induce human T follicular helper cell differentiation through OX40-ligand

T follicular helper cells (Tfh) are implicated in various pathological conditions, but how they differentiate in Th2-skewed environments is unknown. Pattarini et al. delineate a pathway for human Tfh differentiation induced by TSLP through OX40L, relevant to atopic dermatitis.

T follicular helper cells (Tfh) are important regulators of humoral responses. Human Tfh polarization pathways have been thus far associated with Th1 and Th17 polarization pathways. How human Tfh cells differentiate in Th2-skewed environments is unknown. We show that thymic stromal lymphopoietin (TSLP)–activated dendritic cells (DCs) promote human Tfh differentiation from naive CD4 T cells. We identified a novel population, distinct from Th2 cells, expressing IL-21 and TNF, suggestive of inflammatory cells. TSLP-induced T cells expressed CXCR5, CXCL13, ICOS, PD1, BCL6, BTLA, and SAP, among other Tfh markers. Functionally, TSLP-DC–polarized T cells induced IgE secretion by memory B cells, and this depended on IL-4Rα. TSLP-activated DCs stimulated circulating memory Tfh cells to produce IL-21 and CXCL13. Mechanistically, TSLP-induced Tfh differentiation depended on OX40-ligand, but not on ICOS-ligand. Our results delineate a pathway of human Tfh differentiation in Th2 environments.

KLK5 and KLK7 Ablation Fully Rescues Lethality of Netherton Syndrome-Like Phenotype

Netherton syndrome (NS) is a severe skin disease caused by the loss of protease inhibitor LEKTI, which leads to the dysregulation of epidermal proteases and severe skin-barrier defects. KLK5 was proposed as a major protease in NS pathology, however its inactivation is not sufficient to rescue the lethal phenotype of LEKTI-deficient mice. In this study, we further elucidated the in vivo roles of the epidermal proteases in NS using a set of mouse models individually or simultaneously deficient for KLK5 and KLK7 on the genetic background of a novel NS-mouse model. We show that although the ablation of KLK5 or KLK7 is not sufficient to rescue the lethal effect of LEKTI-deficiency simultaneous deficiency of both KLKs completely rescues the epidermal barrier and the postnatal lethality allowing mice to reach adulthood with fully functional skin and normal hair growth. We report that not only KLK5 but also KLK7 plays an important role in the inflammation and defective differentiation in NS and KLK7 activity is not solely dependent on activation by KLK5. Altogether, these findings show that unregulated activities of KLK5 and KLK7 are responsible for NS development and both proteases should become targets for NS therapy.

Transcriptome reveals the overexpression of a kallikrein gene cluster (KLK1/3/7/8/12) in the Tibetans with high altitude-associated polycythemia

High altitude-associated polycythemia (HAPC) is a very common disease. However, it the disease is still unmanageable and the related molecular mechanisms remain largely unclear. In the present study, we aimed to explore the molecular mechanisms responsible for the development of HAPC using transcriptome analysis. Transcriptome analysis was conducted in 3 pairs of gastric mucosa tissues from patients with HAPC and healthy residents at a similar altitude. Endoscopy and histopathological analyses were used to examine the injury to gastric tissues. Molecular remodeling was performed for the interaction between different KLK members and cholesterol. HAPC was found to lead to morphological changes and pathological damage to the gastric mucosa of patients. A total of 10,304 differentially expressed genes (DEGs) were identified. Among these genes, 4,941 DEGs were upregulated, while 5,363 DEGs were downregulated in the patients with HAPC (fold change ≥2, P<0.01 and FDR <0.01). In particular, the kallikrein gene cluster (KLK1/3/7/8/12) was upregulated >17-fold. All the members had high-score binding cholesterol, particularly for the polymers of KLK7. The kallikrein gene cluster (KLK1/3/7/8/12) is on chromosome 19q13.3-13.4. The elevated levels of KLK1, KLK3, KLK7, KLK8 and KLK12 may be closely associated with the hypertension, inflammation, obesity and other gastric injuries associated with polycythemia. The interaction of KLKs and cholesterol maybe play an important role in the development of hypertension. The findings of the present study revealed that HAPC induces gastric injury by upregulating the kallikrein gene cluster (KLK1/3/7/8/12), which can bind cholesterol and result in kallikrein hypertension. These findings provide some basic information for understanding the molecular mechanisms responsible for HAPC and HAPC-related diseases.

Selective Substrates and Inhibitors for Kallikrein-Related Peptidase 7 (KLK7) Shed Light on KLK Proteolytic Activity in the Stratum Corneum

Proteases have pivotal roles in the skin's outermost layer, the epidermis. In the stratum corneum, serine proteases from the kallikrein-related peptidase (KLK) family have been implicated in several key homeostatic processes, including desquamation. However, the precise contribution of specific KLKs to each process remains unclear. To address this, we used a chemical biology approach and designed selective substrates and inhibitors for KLK7, the most abundant KLK protease in the stratum corneum. The resulting KLK7 inhibitor is the most potent inhibitor of this protease reported to date (K_i = 140 pM), and displays at least 1,000-fold selectivity over several proteases that are related by function (KLK5 and KLK14) or specificity (chymotrypsin). We then used substrates and inhibitors for KLK5, KLK7, and KLK14 to explore the activity of each protease in the stratum corneum using casein zymography and an ex vivo desquamation assay. These experiments provide the most detailed assessment of each KLK's contribution to corneocyte shedding in the plantar stratum corneum, revealing that inhibition of KLK7 alone is sufficient to block shedding, whereas KLK5 is also a major contributor. Collectively, these findings unveil chemical tools for studying KLK activity and demonstrate their potential for characterizing KLK biological functions in epidermal homeostasis.

Primary immunodeficiencies associated with eosinophilia

Background

Eosinophilia is not an uncommon clinical finding. However, diagnosis of its cause can be a dilemma once common culprits, namely infection, allergy and reactive causes are excluded. Primary immunodeficiency disorders (PID) are among known differentials of eosinophilia. However, the list of PIDs typically reported with eosinophilia is small and the literature lacks an inclusive list of PIDs which have been reported with eosinophilia. This motivated us to review the literature for all PIDs which have been described to have elevated eosinophils as this may contribute to an earlier diagnosis of PID and further the understanding of eosinophilia.

Methods

A retrospective PubMed, and Google Scholar search using the terms “eosinophilia” and “every individual PID” as classified by Expert Committee of the International Union of Immunological Societies with the limit of the English language was performed. Results were assessed to capture case(s) which reported eosinophilia in the context of PID conditions. Absolute eosinophil counts (AEC) were retrieved from manuscripts whenever reported.

Results

In addition to the typical PID conditions described with eosinophilia, we document that MHC class II deficiency, CD3γ deficiency, STAT1 deficiency (AD form), Kostmann disease, cyclic neutropenia, TCRα deficiency, Papillon-Lefevre syndrome, CD40 deficiency, CD40L deficiency, anhidrotic ectodermal dysplasia with immune deficiency, ataxia-telangiectasia, common variable immunodeficiency disorders (CVID), Blau syndrome, CARD9 deficiency, neonatal onset multisystem inflammatory disease or chronic infantile neurologic cutaneous and articular syndrome (NOMID/CINCA), chronic granulomatous disease, MALT1 deficiency and Roifman syndrome have been noted to have elevated eosinophils. Severe eosinophilia (>5.0 × 10⁹/L) was reported in Omenn syndrome, Wiskott Aldrich syndrome, ADA deficiency, autoimmune lymphoproliferative syndrome, immunodysregulation polyendocrinopathy enteropathy X-linked, STAT3 deficiency, DOCK8 deficiency, CD40 deficiency, MHC II deficiency, Kostmann disease, Papillon-Lefevre syndrome, and CVID.

Conclusions

This literature review shows that there is an extensive list of PIDs which have been reported with eosinophilia. This list helps clinicians to consider an extended differential diagnoses when tasked with exclusion of PID as a cause for eosinophilia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13223-016-0130-4) contains supplementary material, which is available to authorized users.

Eosinophilia Associated with Disorders of Immune Deficiency or Immune Dysregulation

Increased serum eosinophil levels have been associated with multiple disorders of immune deficiency or immune dysregulation. Although primary immunodeficiency diseases are rare, it is important to consider these in the differential diagnosis of patients with eosinophilia. In this review, the clinical features, laboratory findings, diagnosis, and genetic basis of disease of several disorders of immune deficiency or dysregulation are discussed. The article includes autosomal dominant hyper IgE syndrome, DOCK8 deficiency, phosphoglucomutase 3 deficiency, ADA-SCID, Omenn syndrome, Wiskott-Aldrich syndrome, Loeys-Dietz syndrome, autoimmune lymphoproliferative syndrome, immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, Comel-Netherton syndrome, and severe dermatitis, multiple allergies, and metabolic wasting syndrome.

Kallikrein-related peptidases (KLKs) as emerging therapeutic targets: focus on prostate cancer and skin pathologies

INTRODUCTION

Tissue kallikrein and the kallikrein-related peptidases (KLKs) constitute a family of 15 homologous secreted serine proteases with trypsin- or chymotrypsin-like activities, which participate in a broad spectrum of physiological procedures. Deregulated expression and/or activation of the majority of the family members have been reported in several human diseases, thereby making KLKs ideal targets for therapeutic intervention.

AREAS COVERED

In the present review, we summarize the role of KLKs in normal human physiology and pathology, focusing on prostate cancer and skin diseases. Furthermore, we discuss the recent advances in the development of KLK-based therapies. A great number of diverse engineered KLKs inhibitors with improved potency, selectivity and immunogenicity have been synthesized by redesigning examples that are endogenous and naturally occurring. Moreover, encouraging results have been documented using KLKs-based vaccines and immunotherapies, as well as KLKs-mediated activation of pro-drugs. Finally, KLKs-targeting aptamers and KLKs-based imaging tools represent novel approaches towards the exploitation of KLKs' therapeutic value.

EXPERT OPINION

The central/critical roles of KLK family in several human pathologies highlight KLKs as attractive molecular targets for developing novel therapeutics.