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KLK5 Inactivation Reverses Cutaneous Hallmarks of Netherton Syndrome.

ABSTRACT: Netherton Syndrome (NS) is a rare and severe autosomal recessive skin disease which can be life-threatening in infants. The disease is characterized by extensive skin desquamation, inflammation, allergic manifestations and hair shaft defects. NS is caused by loss-of-function mutations in SPINK5 encoding the LEKTI serine protease inhibitor. LEKTI deficiency results in unopposed activities of kallikrein-related peptidases (KLKs) and aberrantly increased proteolysis in the epidermis. Spink5?/? mice recapitulate the NS phenotype, display enhanced epidermal Klk5 and Klk7 protease activities and die within a few hours after birth because of a severe skin barrier defect. However the contribution of these various proteases in the physiopathology remains to be determined. In this study, we developed a new murine model in which Klk5 and Spink5 were both knocked out to assess whether Klk5 deletion is sufficient to reverse the NS phenotype in Spink5?/? mice. By repeated intercrossing between Klk5?/? mice with Spink5?/? mice, we generated Spink5?/?Klk5?/? animals. We showed that Klk5 knock-out in Lekti-deficient newborn mice rescues neonatal lethality, reverses the severe skin barrier defect, restores epidermal structure and prevents skin inflammation. Specifically, using in situ zymography and specific protease substrates, we showed that Klk5 knockout reduced epidermal proteolytic activity, particularly its downstream targets proteases KLK7, KLK14 and ELA2. By immunostaining, western blot, histology and electron microscopy analyses, we provide evidence that desmosomes and corneodesmosomes remain intact and that epidermal differentiation is restored in Spink5?/?Klk5?/?. Quantitative RT-PCR analyses and immunostainings revealed absence of inflammation and allergy in Spink5?/?Klk5?/? skin. Notably, Il-1?, Il17A and Tslp levels were normalized. Our results provide in vivo evidence that KLK5 knockout is sufficient to reverse NS-like symptoms manifested in Spink5?/? skin. These findings illustrate the crucial role of protease regulation in skin homeostasis and inflammation, and establish KLK5 inhibition as a major therapeutic target for NS.

SUBMITTER: Furio L

PROVIDER: S-EPMC4577096 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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KLK5 Inactivation Reverses Cutaneous Hallmarks of Netherton Syndrome.

Furio Laetitia L Pampalakis Georgios G Michael Iacovos P IP Nagy Andras A Sotiropoulou Georgia G Hovnanian Alain A

PLoS genetics 20150921 9

Netherton Syndrome (NS) is a rare and severe autosomal recessive skin disease which can be life-threatening in infants. The disease is characterized by extensive skin desquamation, inflammation, allergic manifestations and hair shaft defects. NS is caused by loss-of-function mutations in SPINK5 encoding the LEKTI serine protease inhibitor. LEKTI deficiency results in unopposed activities of kallikrein-related peptidases (KLKs) and aberrantly increased proteolysis in the epidermis. Spink5⁻/⁻ mice ...[more]

PMID: 26390218

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Project description:ImportanceNetherton 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.ObjectiveTo evaluate the clinical response of NS to treatment with the IL-17 antagonist secukinumab.Design, setting, and participantsThis 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 measuresExpression 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.ResultsIn 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 relevanceThis 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.

Project description:BACKGROUND:Netherton syndrome (NS) is a rare life-threatening syndrome caused by SPINK5 mutations leading to a skin barrier defect and a severe atopic diathesis. NS patients are prone to bacterial infections, but the understanding of the underlying immune deficiency is incomplete. RESULTS:We analyzed blood lymphocyte phenotypes and function in relation to clinical infections in 11 Finnish NS patients, aged 3 to 17?years, and healthy age-matched controls. The proportion of B cells (CD19+) and naïve B cells (CD27-, IgD+) were high while memory B cells (CD27+) and switched memory B cells (CD27+IgM-IgD-), crucial for the secondary response to pathogens, was below or in the lowest quartile of the reference values in 8/11 (73%) and 9/11 (82%) patients, respectively. The proportion of activated non-differentiated B cells (CD21low, CD38low) was below or in the lowest quartile of the reference values in 10/11 (91%) patients. Despite normal T cell counts, the proportion of naïve CD4+ T cells was reduced significantly and the proportion of CD8+ T central memory significantly elevated. An increased proportion of CD57+ CD8+ T cells indicated increased differentiation potential of the T cells. The proportion of cytotoxic NK cells was elevated in NS patients in phenotypic analysis based on CD56DIM, CD16+ and CD27- NK cells but in functional analysis, decreased expression of CD107a/b indicated impaired cytotoxicity. The T and NK cell phenotype seen in NS patients also significantly differed from that of age-matched atopic dermatitis (AD) patients, indicating a distinctive profile in NS. The frequency of skin infections correlated with the proportion of CD62L+ T cells, naïve CD4+ and CD27+ CD8+ T cells and with activated B cells. Clinically beneficial intravenous immunoglobulin therapy (IVIG) increased naïve T cells and terminal differentiated effector memory CD8+ cells and decreased the proportion of activated B cells and plasmablasts in three patients studied. CONCLUSIONS:This study shows novel quantitative and functional aberrations in several lymphocyte subpopulations, which correlate with the frequency of infections in patients with Netherton syndrome. IVIG therapy normalized some dysbalancies and was clinically beneficial.

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KLK5 Inactivation Reverses Cutaneous Hallmarks of Netherton Syndrome.

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KLK5 Inactivation Reverses Cutaneous Hallmarks of Netherton Syndrome.

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