CHILD syndrome: A modified pathogenesis-targeted therapeutic approach

Treatments for Non-Syndromic Inherited Ichthyosis, Including Emergent Pathogenesis-Related Therapy

The term 'inherited ichthyosis' refers to a heterogeneous group of mendelian disorders of cornification that involve the integument with varying degrees of scaling. The management of ichthyosis poses a challenge for most physicians. Treatment options proposed in the literature include moisturizers, topical keratolytics, topical and systemic vitamin D analogues, and topical and systemic retinoids; however, some of these modalities are less reliable than others. Despite the therapeutic impasse imposed by the options above, the emergence of pathogenesis-based treatments along with novel gene therapies appear promising and hold the potential to halt or even revert disorders that arise from single genetic mutations, although research is still quite lacking in this domain. Hence, this review aims to highlight the various treatment modalities available for the management of the cutaneous manifestations of non-syndromic inherited ichthyosis, with an added emphasis on pathogenesis-targeted therapies.

New developments in the molecular treatment of ichthyosis: review of the literature

Ichthyosis covers a wide spectrum of diseases affecting the cornification of the skin. In recent years, new advances in understanding the pathophysiology of ichthyosis have been made. This knowledge, combined with constant development of pathogenesis-based therapies, such as protein replacement therapy and gene therapy, are rather promising for patients with inherited skin diseases. Several ongoing trials are investigating the potency of these new approaches and various studies have already been published. Furthermore, a lot of case series report that biological therapeutics are effective treatment options, mainly for Netherton syndrome and autosomal recessive congenital ichthyosis. It is expected that some of these new therapies will prove their efficacy and will be incorporated in the treatment of ichthyosis.

Ichthyosis and hereditary cornification disorders in dogs

The stratum corneum (SC), the outermost layer of the epidermis, serves a crucial role in maintaining body hydration and protection from environmental insults. When the stratum corneum is injured or when the genetic blueprints are flawed, the body is at risk of dehydration, secondary infections and allergen sensitization. Advancements in veterinary dermatology have revealed a wide gamut of disease from relatively benign to lethal that specifically arise from flawed structural proteins, enzymes or lipids needed to create the corneocytes and lipid bilayers of the SC. Some conditions closely mimic their human counterparts while others are unique to the dog. This review will focus on forms of ichthyosis in the dog.

The Forgotten Phacomatoses: A Neuroimaging Review of Rare Neurocutaneous Disorders

Phakomatoses, or neurocutaneous syndromes, are a heterogeneous group of rare genetic disorders that predominantly affect structures arising from the embryonic ectoderm, namely the skin, eye globe, retina, tooth enamel, and central nervous system. Other organs are also involved in some syndromes, mainly cardiovascular, pulmonary, renal, and musculoskeletal systems. Currently, more than sixty distinct entities belonging to this category have been described in the literature. Common phakomatoses include conditions like Neurofibromatosis and Tuberous sclerosis. Several review papers have focused on various aspects of these common conditions, including clinical presentation, genetic and molecular basis, and neuroimaging features. In this review, we focus on rare neurocutaneous syndromes: Melanophakomatoses (Ie, Neurocutaneous Melanosis, and Incontinentia Pigmenti), Vascular Phakomatoses (Ie, Ataxia Telangiectasia and PHACE Syndrome), and other conditions such as Cowden Syndrome, Basal Nevus Syndrome, Schwannomatosis, Progressive Facial Hemiatrophy, Gomez-Lopez-Hernandez Syndrome, Wyburn-Mason Syndrome, CHILD Syndrome, and Proteus Syndrome. We also review the neuroradiologic manifestations of these conditions as a guide for neurologists and neuroradiologists in their daily practice.

Ichthyoses-A Clinical and Pathological Spectrum from Heterogeneous Cornification Disorders to Inflammation

Ichthyoses are inborn keratinization disorders affecting the skin only (non-syndromic) or are associated with diseases of internal organs (syndromic). In newborns, they can be life-threatening. The identification of the gene defects resulted in reclassification and a better understanding of the pathophysiology. Histopathologic patterns include orthohyperkeratosis with a reduced or well-developed stratum granulosum, hyperkeratosis with ortho- and parakeratosis with preserved or prominent stratum granulosum, and epidermolytic ichthyosis. Another pattern features “perinuclear vacuoles and binucleated keratinocytes”, which is associated with keratin mutations. Some ichthyoses are histologically defined by psoriasis-like features, and distinct subtypes show follicular hyperkeratosis. In addition to histological and immunohistochemical methods, these patterns allow a better histopathologic diagnosis.

NSDHL promotes triple-negative breast cancer metastasis through the TGFβ signaling pathway and cholesterol biosynthesis

PURPOSE

Metastasis is the main cause of breast cancer mortality. Recent studies have proved that lipid metabolic reprogramming plays critical roles in breast cancer carcinogenesis and metastasis. We aim to identify critical lipid metabolism genes in breast cancer metastasis.

METHODS

We designed and cloned a CRISPR pooled library containing lipid metabolic gene guide RNAs and performed a genetic screen in vivo. Transwell assay and animal experiments were used to evaluate cell metastatic ability in vitro or in vivo, respectively. We performed immunohistochemistry with breast cancer tissue microarray to study the clinical significance of NSDHL.

FINDINGS

We identified a cholesterol metabolic enzyme, NSDHL, as a potential metastatic driver in triple-negative breast cancer. NSDHL was highly expressed in breast cancer tissues and predicted a poor prognosis. NSDHL knockdown significantly suppressed cell proliferation and migration. Mechanistically, NSDHL activated the TGFβ signaling pathway by inhibiting the endosomal degradation of TGFβR2. In addition, blocking the upstream metabolism of NSDHL with ketoconazole rescued cancer metastasis and TGFβR2 degradation. However, the inactivation of NSDHL (Y151X) did not rescue the migration ability and the TGFβR2 protein expression.

CONCLUSION

Taken together, our findings established that NSDHL serves as a metastatic driver, and its function depends on its enzyme activity in cholesterol biosynthesis and is mediated by the NSDHL-TGFβR2 signal pathway. Our study indicated that NSDHL and steroid biosynthesis may serve as new drug targets for patients with advanced breast cancer.

Topical cholesterol/lovastatin for the treatment of porokeratosis: A pathogenesis-directed therapy

BACKGROUND

Porokeratosis is associated with mevalonate pathway gene mutations. Therapeutic options are few and often limited in efficacy. We hypothesized that topical therapy that aims to replenish cholesterol, an essential mevalonate pathway end-product, and block the accumulation of mevalonate pathway toxic metabolites could alleviate porokeratosis.

OBJECTIVE

To study the efficacy of topical cholesterol/lovastatin in different variants of porokeratosis.

METHODS

We enrolled a series of 5 porokeratosis patients,1 with disseminated superficial actinic porokeratosis, 2 with porokeratosis palmaris et plantaris disseminata, and 2 with linear porokeratosis. Patients were genotyped before initiation of therapy. Patients then applied topical cholesterol/lovastatin twice daily to a unilaterally defined treatment area for up to 3 months. The response was evaluated and patients photographed at every visit.

RESULTS

Three patients had MVD mutations, and 2 patients had PMVK mutations. Treatment with topical cholesterol/lovastatin (but not cholesterol alone) resulted in near complete clearance of disseminated superficial actinic porokeratosis lesions after 4 weeks of therapy and moderate improvement of porokeratosis palmaris et plantaris disseminata lesions and linear porokeratosis lesions. There were no adverse events.

LIMITATIONS

Case series design with a small number of patients.

CONCLUSION

Topical cholesterol/lovastatin is an effective and well-tolerated therapy for porokeratosis that underscores the utility of a pathogenesis-based therapy that replaces deficient end products and prevents accumulation of potentially toxic precursors.

A missense variant in the NSDHL gene in a Chihuahua with a congenital cornification disorder resembling inflammatory linear verrucous epidermal nevi

Congenital hemidysplasia with ichthyosiform nevus and limb defects syndrome in humans is a genodermatosis characterized by inflammatory linear verrucous epidermal nevi (ILVEN), often showing a striking lateralization pattern. It is caused by variants in the NSDHL gene encoding a 3β-hydroxysteroid dehydrogenase involved in the cholesterol biosynthesis pathway. In the present study, we investigated a female Chihuahua, which showed clinical and histological signs of ILVEN. We performed a candidate gene analysis in the affected animal. This analysis revealed a single missense variant in the NSDHL gene in the affected dog (XM_014111859.2:c.700G>A). The variant is predicted to cause a non-conservative amino acid change from glycine to arginine, XP_013967334.1:p.(Gly234Arg). The mutant allele was absent from WGS data of 594 genetically diverse dogs and eight wolves. Sanger sequencing confirmed that the variant was heterozygous in the affected dog and absent from 22 control Chihuahuas. Based on the knowledge about the functional impact of NSDHL variants in dogs and other species, c.700G>A is probably pathogenic and a convincing candidate causative variant for the observed skin lesions in the affected Chihuahua.

Use of Topical Glycolic Acid Plus a Lovastatin-Cholesterol Combination Cream for the Treatment of Autosomal Recessive Congenital Ichthyoses

Importance

Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of disorders caused by defects in signaling pathways involved in epidermal proliferation and differentiation, leading to a wide range of skin manifestations. Therapeutic options are limited and often unsatisfactory. Topical cholesterol and statin as a combined formulation has proven successful in the treatment of patients with CHILD syndrome (congenital hemidysplasia ichthyosis and limb defects).

Objective

To assess change in disease severity score after a 3-month therapeutic regimen consisting of a glycolic acid, 10% to 20%, cream and a combination cream of lovastatin, 2%, with cholesterol, 2%, in the treatment of ARCI.

Design, Setting, and Participants

This case series of 15 patients with ARCI was conducted at the American University of Beirut, a referral center in the Middle East region for genodermatoses, between May 2017 and January 2018. No age groups were excluded; all patients were from the Middle East area; and all were initially not responsive to treatment with hydrating creams in combination with urea creams, 30% to 40%, or glycolic acid, 10% to 20%. Excluded were patients who had been taking systemic retinoids within 3 months before the start of the study.

Interventions

A 3-month therapeutic regimen of glycolic acid, 10% to 20%, cream and a combination of lovastatin, 2%, with cholesterol, 2%, cream.

Main Outcomes and Measures

Percentage change in disease severity scores following 2 and 3 months of study treatment.

Results

Of the 15 patients included in the study, 10 were male (mean age, 11.2 years; age range, 2-38 years). The average percentage reduction in the disease severity score was 33.7% at 2 months (from 60.8 to 40.2) and 57.5% at 3 months (from 60.8 to 21.9). Adverse effects were mild and consisted mainly of irritation and burning.

Conclusions and Relevance

These findings suggest a benefit from a treatment regimen consisting of glycolic acid, 10% to 20%, and a combination of lovastatin, 2%, with cholesterol, 2%, in the treatment of ARCI. This combination of creams might also prove to be beneficial in other types of ichthyoses and other dermatological diseases with a defective skin barrier.

Genetic variant in the NSDHL gene in a cat with multiple congenital lesions resembling inflammatory linear verrucous epidermal nevi

BACKGROUND

The feline counterpart of human inflammatory linear verrucous epidermal nevus (ILVEN) has been described; however, the possible underlying developmental defect has not been investigated.

OBJECTIVE

To report a case of multiple ILVEN-like lesions in a cat with a genetic variant in the NSDHL gene.

ANIMALS

A 2-year-old, female, domestic short hair cat with a history of multiple alopecic, verrucous, hyperpigmented and erythematous skin lesions, following Blaschko's lines on the head, the limbs, the trunk and paw pads.

METHODS AND RESULTS

According to the clinical and histopathological findings, a diagnosis of multiple ILVEN-like lesions was made. Genetic investigation revealed a heterozygous missense variant in the X-chromosomal NSDHL gene predicted to lead to a loss-of-function of the NSDHL protein.

CONCLUSIONS AND CLINICAL IMPORTANCE

To the best of the authors' knowledge, this is the first case of feline ILVEN-like lesions in which a genetic cause has been proposed. Future studies to establish a causal relationship between NSDHL variants and skin lesions might lead to pathogenesis-directed treatments.