Ex-vivo gene therapy restores LEKTI activity and corrects the architecture of Netherton syndrome-derived skin grafts

Netherton syndrome (NS) is a debilitating congenital skin disorder caused by mutations in the SPINK5 gene encoding the lymphoepithelial Kazal-type-related inhibitor (LEKTI). It is characterized by defective keratinization, recurrent infections, and hypernatraemic dehydration with a mortality rate of about 10% in the first year of life. Currently, there are no curative treatments for NS. We have developed a HIV-1 based, self-inactivating lentiviral vector to express SPINK5 in keratinocytes as part of an ex-vivo gene therapy strategy for NS. High transduction efficiency was achieved in NS keratinocytes and reconstitution of LEKTI expression was confirmed in previously deficient cells. These genetically corrected keratinocytes were further tested in an in vitro organotypic culture (OTC) system and in vivo mouse/human skin engraftment model. Results showed correction of epidermal architecture in both OTCs and regenerated skin grafts. Importantly, the results from corrected skin grafts indicated that even where detectable LEKTI expression was restored to a limited numbers of cells, a wider bystander benefit occurred around these small populations. As LEKTI is a secreted protein, the genetically modified graft may provide not only an immediate local protective barrier, but also act as a source of secreted LEKTI providing a generalized benefit following ex-vivo gene therapy.

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

Netherton syndrome (NS) is an orphan genetic skin disease with a profound skin barrier defect and severe allergic manifestations. NS is caused by loss of function mutations in SPINK5 encoding lympho-epithelial Kazal-type inhibitor (LEKTI), a secreted multi-domain serine protease inhibitor expressed in stratified epithelia. Studies in mouse models and in NS patients have established that unopposed kallikrein 5 activity triggers stratum corneum detachment and activates PAR-2 signaling, leading to the autonomous production of pro-allergic and pro-inflammatory mediators. This emerging knowledge on NS pathogenesis has highlighted a central role for protease regulation in skin homeostasis but also in the complexity of the disease, and holds the promise of new specific treatments.

Toward Combined Cell and Gene Therapy for Genodermatoses

To date, more than 200 monogenic, often devastating, skin diseases have been described. Because of unmet medical needs, development of long-lasting and curative therapies has been consistently attempted, with the aim of correcting the underlying molecular defect. In this review, we will specifically address the few combined cell and gene therapy strategies that made it to the clinics. Based on these studies, what can be envisioned for the future is a patient-oriented strategy, built on the specific features of the individual in need. Most likely, a combination of different strategies, approaches, and advanced therapies will be required to reach the finish line at the end of the long and winding road hampering the achievement of definitive treatments for genodermatoses.

Rapid and easy diagnosis of Netherton syndrome with dermoscopy

BACKGROUND

Netherton syndrome is a rare autosomal recessive disease demonstrating ichthyosis linearis circumflexa, atopic findings, and hair shaft anomalies. Trichorrhexis invaginata is the pathognomonic hair shaft anomaly seen in this syndrome.

OBJECTIVE

In recent years, hair shaft anomalies have been described as "matchstick" and "golf tee" signs. We present a patient with Netherton syndrome diagnosed by the presence of matchstick and golf tee hairs in addition to trichorrhexis invaginata.

Netherton syndrome and its multifaceted defective protein LEKTI

Netherton syndrome (NS, OMIM 256500) is a rare autosomal recessive disorder manifesting with congenital ichthyosis, a specific hair shaft abnormality named trichorrhexis invaginata, and atopic manifestations. Because of severe complications frequently occurring in the neonatal period, NS prognosis can be poor in infancy. NS is due to loss-of-function mutations in the SPINK5 gene and to the consequent lack of expression of its encoded protein LEKTI in the skin and all stratified epithelial tissues. Following the identification of the NS causative gene and protein, specific diagnostic tools have been developed, thus breaking up the challenge of distinguishing NS from other congenital ichthyoses with overlapping features, and from severe, early-onset forms of atopic dermatitis or psoriasis. Intensive efforts to extend the knowledge into the pathomechanisms of NS have also been made. However, NS management is still problematic due to the lack of specific treatment and unmet needs. This overview summarizes the current state of the art in NS research with an emphasis on the progress made toward disease-specific innovative therapy development.

Developing a Core Outcome Set for Netherton Syndrome: An International Multi-Stakeholder e-Delphi Consensus Study

INTRODUCTION

Netherton syndrome (NS; OMIM#256500) is a rare and severe disorder of epidermal maturation and keratinization caused by pathogenic variants in the serine protease inhibitor Kazal type 5 (SPINK5), leading to severe skin barrier impairment. Although effective treatment is crucial for NS patients, there is a lack of knowledge on what the best treatment options are for these patients. Large heterogeneity in reported outcomes and measurement instruments hinders accurate comparison of treatment results across studies and the development of a treatment guideline. Therefore, we aimed to develop a core outcome set (COS) for NS that can be used in clinical care and research.

METHODS

This study was performed in accordance with the recommendations of the Core Outcome Measures in Effectiveness Trials (COMET) initiative. After identification of outcomes through a literature search and classification based on the International Classification of Functioning and taxonomies published by the COMET initiative, discussion groups were organized at the 2nd International Netherton Congress 2022 to finalize the provisional outcome list. Through a 2-round e-Delphi, 41 stakeholders (patients and family members, professionals, and representatives of industry) from 14 countries rated the importance of the outcomes using a 9-point Likert scale. An online consensus meeting attended by 14 stakeholders finalized the COS.

RESULTS

The COS for NS comprised 21 outcomes in 10 domains. These included four "skin" outcomes, two "sensation" outcomes, two "side-effects of treatment" outcomes, one "vitality" outcome, one "emotional functioning" outcome, two "physical development" outcomes, two "nutrition" outcomes, two "infections" outcomes, two "allergies" outcomes, and three "assessment results" outcomes.

CONCLUSION

In this study, consensus was reached on 21 outcomes to be included in the COS for NS. The selection of outcomes in the COS underlines that NS not only affects the skin but is a disease requiring a broad multidisciplinary approach in clinical care and research. International implementation of this COS will lead to more uniform reporting, thereby enabling comparison of study results, which may facilitate future treatment guideline development. The next step is to further conceptually define the outcomes and reach consensus on how to measure these.

INTRODUCTION

Netherton syndrome (NS; OMIM#256500) is a rare and severe disorder of epidermal maturation and keratinization caused by pathogenic variants in the serine protease inhibitor Kazal type 5 (SPINK5), leading to severe skin barrier impairment. Although effective treatment is crucial for NS patients, there is a lack of knowledge on what the best treatment options are for these patients. Large heterogeneity in reported outcomes and measurement instruments hinders accurate comparison of treatment results across studies and the development of a treatment guideline. Therefore, we aimed to develop a core outcome set (COS) for NS that can be used in clinical care and research.

METHODS

This study was performed in accordance with the recommendations of the Core Outcome Measures in Effectiveness Trials (COMET) initiative. After identification of outcomes through a literature search and classification based on the International Classification of Functioning and taxonomies published by the COMET initiative, discussion groups were organized at the 2nd International Netherton Congress 2022 to finalize the provisional outcome list. Through a 2-round e-Delphi, 41 stakeholders (patients and family members, professionals, and representatives of industry) from 14 countries rated the importance of the outcomes using a 9-point Likert scale. An online consensus meeting attended by 14 stakeholders finalized the COS.

RESULTS

The COS for NS comprised 21 outcomes in 10 domains. These included four "skin" outcomes, two "sensation" outcomes, two "side-effects of treatment" outcomes, one "vitality" outcome, one "emotional functioning" outcome, two "physical development" outcomes, two "nutrition" outcomes, two "infections" outcomes, two "allergies" outcomes, and three "assessment results" outcomes.

CONCLUSION

In this study, consensus was reached on 21 outcomes to be included in the COS for NS. The selection of outcomes in the COS underlines that NS not only affects the skin but is a disease requiring a broad multidisciplinary approach in clinical care and research. International implementation of this COS will lead to more uniform reporting, thereby enabling comparison of study results, which may facilitate future treatment guideline development. The next step is to further conceptually define the outcomes and reach consensus on how to measure these.