[Show abstract][Hide abstract] ABSTRACT: Netherton syndrome (NS) is a severe genetic skin disease in which absence of a key protease inhibitor causes congenital exfoliative erythroderma, eczematous-like lesions, and atopic manifestations. Several proteases are overactive in NS, including kallikrein-related peptidase (KLK) 5, KLK7, and elastase-2 (ELA2), which are suggested to be part of a proteolytic cascade initiated by KLK5. To address the role of KLK5 in NS, we have generated a new transgenic murine model expressing human KLK5 in the granular layer of the epidermis (Tg-KLK5). Transgene expression resulted in increased proteolytic activity attributable to KLK5 and its downstream targets KLK7, KLK14, and ELA2. Tg-KLK5 mice developed an exfoliative erythroderma with scaling, growth delay, and hair abnormalities. The skin barrier was defective and the stratum corneum was detached through desmosomal cleavage. Importantly, Tg-KLK5 mice displayed cutaneous and systemic hallmarks of severe inflammation and allergy with pruritus. The skin showed enhanced expression of inflammatory cytokines and chemokines, infiltration of immune cells, and markers of Th2/Th17/Th22 T cell responses. Moreover, serum IgE and Tslp levels were elevated. Our study identifies KLK5 as an important contributor to the NS proteolytic cascade and provides a new and viable model for the evaluation of future targeted therapies for NS or related diseases such as atopic dermatitis.
Journal of Experimental Medicine 02/2014; · 13.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Food-grade lactic acid bacteria (LAB) are good candidates for the development of oral vectors, and are attractive alternatives to attenuated pathogens, for mucosal delivery strategies. In this review, we summarize recent results on the use of LAB as mucosal delivery vectors for therapeutic proteins and DNA vaccines. Most of this work has been based on the model LAB, Lactococcus lactis, which is suitable for the heterologous expression of therapeutic proteins. Recombinant lactococci and lactobacilli strains expressing antiproteases and antioxidant enzymes have been tested successfully for their prophylactic and therapeutic effects in murine models of colitis. Recombinant lactococci secreting autoantigens have been found to be effective for the treatment of type 1 diabetes. Also, recombinant lactococci delivering DNA were able to prevent a bovine β-lactoglobulin (BLG)-allergic reaction in mice. We believe that these various coherent findings demonstrate the potential value of using LAB, particularly lactococci and lactobacilli strains, to develop novel vectors for the therapeutic delivery of proteins to mucosal surfaces. Further tests and in particular human clinical trials are now important next steps to conclude on the benefit of these approaches for human health.
Current opinion in microbiology 07/2013; · 7.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Elafin, a natural protease inhibitor expressed in healthy intestinal mucosa, has pleiotropic anti-inflammatory properties in vitro and in animal models. We found that mucosal expression of Elafin is diminished in patients with inflammatory bowel disease (IBD). This defect is associated with increased elastolytic activity (elastase-like proteolysis) in colon tissue. We engineered two food-grade strains of lactic acid bacteria (LAB) to express and deliver Elafin to the site of inflammation in the colon to assess the potential therapeutic benefits of the Elafin-expressing LAB. In mouse models of acute and chronic colitis, oral administration of Elafin-expressing LAB decreased elastolytic activity and inflammation and restored intestinal homeostasis. Furthermore, when cultures of human intestinal epithelial cells were treated with LAB secreting Elafin, the inflamed epithelium was protected from increased intestinal permeability and from the release of cytokines and chemokines, both of which are characteristic of intestinal dysfunction associated with IBD. Together, these results suggest that oral delivery of LAB secreting Elafin may be useful for treating IBD in humans.
Science translational medicine 10/2012; 4(158):158ra144. · 10.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Netherton syndrome (NS) is a severe skin disease caused by loss-of-function mutations in SPINK5 (serine protease inhibitor Kazal-type 5) encoding the serine protease inhibitor LEKTI (lympho-epithelial Kazal type-related inhibitor). Here, we disclose new SPINK5 defects in 12 patients, who presented a clinical triad suggestive of NS with variations in inter- and intra-familial disease expression. We identified a new and frequent synonymous mutation c.891C>T (p.Cys297Cys) in exon 11 of the 12 NS patients. This mutation disrupts an exonic splicing enhancer sequence and causes out-of-frame skipping of exon 11. Haplotype analysis indicates that this mutation is a founder mutation in Greece. Two other new deep intronic mutations, c.283-12T>A in intron 4 and c.1820+53G>A in intron 19, induced partial intronic sequence retention. A new nonsense c.2557C>T (p.Arg853X) mutation was also identified. All mutations led to a premature termination codon resulting in no detectable LEKTI on skin sections. Two patients with deep intronic mutations showed residual LEKTI fragments in cultured keratinocytes. These fragments retained some functional activity, and could therefore, together with other determinants, contribute to modulate the disease phenotype. This new founder mutation, the most frequent mutation described in European populations so far, and these unusual intronic mutations, widen the clinical and molecular spectrum of NS and offer new diagnostic perspectives for NS patients.
[Show abstract][Hide abstract] ABSTRACT: Netherton syndrome (NS) is a severe genodermatosis characterized by abnormal scaling and constant atopic manifestations. NS is caused by mutations in SPINK5 (Serine Protease INhibitor Kazal-type 5), which encodes LEKTI (LymphoEpithelial Kazal Type-related Inhibitor). Lack of LEKTI causes stratum corneum detachment secondary to epidermal proteases hyperactivity. Whereas a skin barrier defect is generally regarded as a major cause for atopy, we previously identified a cell-autonomous signaling cascade that triggers pro-Th2 cytokine thymic stromal lymphopoietin (TSLP) production in LEKTI-deficient epidermis. This signaling is initiated by unrestricted kallikrein 5 (KLK5) activity, which directly activates proteinase-activated receptor 2 (PAR2)-mediated expression of TSLP and favors a cutaneous proallergic microenvironment independently of the environment and of the adaptive immune system. To further confirm these results in vivo, we generated Spink5/Par2 double knockout (DKO) mice. At embryonic day 19.5, these mice display a dramatic decrease in TSLP expression, although stratum corneum detachment persists, confirming the role of the KLK5-PAR2 cascade in TSLP-mediated early proallergic signaling. However, deletion of Par2 in adult DKO-grafted skin does not rescue the inflammatory phenotype probably resulting from stratum corneum detachment. We conclude that several mechanisms trigger and maintain the inflammatory phenotype in NS. These include skin barrier impairment, mechanical stress secondary to stratum corneum detachment, as well as protease-induced proinflammatory and proallergic pathways, including PAR2-mediated overexpression of TSLP.
Journal of Investigative Dermatology 12/2010; 130(12):2736-42. · 6.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A growing body of evidence suggests that the multifunctional protein E4F1 is involved in signaling pathways that play essential roles during normal development and tumorigenesis. We generated E4F1 conditional knockout mice to address E4F1 functions in vivo in newborn and adult skin. E4F1 inactivation in the entire skin or in the basal compartment of the epidermis induces skin homeostasis defects, as evidenced by transient hyperplasia in the interfollicular epithelium and alteration of keratinocyte differentiation, followed by loss of cellularity in the epidermis and severe skin ulcerations. E4F1 depletion alters clonogenic activity of epidermal stem cells (ESCs) ex vivo and ends in exhaustion of the ESC pool in vivo, indicating that the lesions observed in the E4F1 mutant skin result, at least in part, from cell-autonomous alterations in ESC maintenance. The clonogenic potential of E4F1 KO ESCs is rescued by Bmi1 overexpression or by Ink4a/Arf or p53 depletion. Skin phenotype of E4F1 KO mice is also delayed in animals with Ink4a/Arf and E4F1 compound gene deficiencies. Our data identify a regulatory axis essential for ESC-dependent skin homeostasis implicating E4F1 and the Bmi1-Arf-p53 pathway.
Proceedings of the National Academy of Sciences 11/2010; 107(49):21076-81. · 9.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The human epidermis serves 2 crucial barrier functions: it protects against water loss and prevents penetration of infectious agents and allergens. The physiology of the epidermis is maintained by a balance of protease and antiprotease activities, as illustrated by the rare genetic skin disease Netherton syndrome (NS), in which impaired inhibition of serine proteases causes severe skin erythema and scaling. Here, utilizing mass spectrometry, we have identified elastase 2 (ELA2), which we believe to be a new epidermal protease that is specifically expressed in the most differentiated layer of living human and mouse epidermis. ELA2 localized to keratohyalin granules, where it was found to directly participate in (pro-)filaggrin processing. Consistent with the observation that ELA2 was hyperactive in skin from NS patients, transgenic mice overexpressing ELA2 in the granular layer of the epidermis displayed abnormal (pro-)filaggrin processing and impaired lipid lamellae structure, which are both observed in NS patients. These anomalies led to dehydration, implicating ELA2 in the skin barrier defect seen in NS patients. Thus, our work identifies ELA2 as a major new epidermal protease involved in essential pathways for skin barrier function. These results highlight the importance of the control of epidermal protease activity in skin homeostasis and designate ELA2 as a major protease driving the pathogenesis of NS.
The Journal of clinical investigation 02/2010; 120(3):871-82. · 15.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Proteinase inhibitors are of high pharmaceutical interest and are drug candidates for a variety of indications. Specific kallikrein inhibitors are important for their antitumor activity and their potential application to the treatment of skin diseases. In this study we describe the synthesis of domain 6 of the kallikrein inhibitor Lympho-Epithilial Kazal-Type Inhibitor (LEKTI) by the fragment condensation method and site-directed cystine bridge formation. To obtain the linear LEKTI precursor, the condensation was best performed in solution, coupling the protected fragment 1-22 to 23-68. This method yielded LEKTI domain 6 of high purity and equipotent to the recombinantly produced peptide.
[Show abstract][Hide abstract] ABSTRACT: A minority of collodion babies, called 'self-healing collodion babies', heal spontaneously. We describe a novel clinical phenotype of acral self-healing collodion baby caused by a new TGM1 mutation. The proband, born to healthy parents, presented at birth as a collodion baby strictly localized to the extremities. The skin condition returned to normal at the age of 3 weeks. The older sister was born as a generalized collodion baby; the condition then developed into lamellar ichthyosis. Molecular analysis of TGM1 revealed three novel mutations in the family. The proband was compound heterozygous for the p.Val359Met and p.Arg396His mutations, whereas the older sister was compound heterozygous for p.Arg396His and a deletion mutation c.1922_1926+2delGGCCTGT. Structural modelling of the p.Val359Met mutation suggested a minor disruption of the protein structure, whereas a modification of protein-protein interaction was predicted for p.Arg396His. These predictions corroborated the analysis of recombinant transglutaminase (TGase)-1 proteins carrying the p.Val359Met and p.Arg396His mutations. Both showed decreased levels of protein expression: p.Val359Met displayed residual activity (12.8%), while p.Arg396His caused a dramatic loss of activity (3.3%). These observations demonstrate for the first time that TGM1 mutations can be associated with acral self-healing collodion baby, and expand the clinical spectrum of TGase-1 deficiency.
British Journal of Dermatology 07/2009; 161(2):456-63. · 3.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Netherton syndrome (NS) is a severe genetic skin disease with constant atopic manifestations that is caused by mutations in the serine protease inhibitor Kazal-type 5 (SPINK5) gene, which encodes the protease inhibitor lymphoepithelial Kazal-type-related inhibitor (LEKTI). Lack of LEKTI causes stratum corneum detachment secondary to epidermal proteases hyperactivity. This skin barrier defect favors allergen absorption and is generally regarded as the underlying cause for atopy in NS. We show for the first time that the pro-Th2 cytokine thymic stromal lymphopoietin (TSLP), the thymus and activation-regulated chemokine, and the macrophage-derived chemokine are overexpressed in LEKTI-deficient epidermis. This is part of an original biological cascade in which unregulated kallikrein (KLK) 5 directly activates proteinase-activated receptor 2 and induces nuclear factor kappaB-mediated overexpression of TSLP, intercellular adhesion molecule 1, tumor necrosis factor alpha, and IL8. This proinflammatory and proallergic pathway is independent of the primary epithelial failure and is activated under basal conditions in NS keratinocytes. This cell-autonomous process is already established in the epidermis of Spink5(-/-) embryos, and the resulting proinflammatory microenvironment leads to eosinophilic and mast cell infiltration in a skin graft model in nude mice. Collectively, these data establish that uncontrolled KLK5 activity in NS epidermis can trigger atopic dermatitis (AD)-like lesions, independently of the environment and the adaptive immune system. They illustrate the crucial role of protease signaling in skin inflammation and point to new therapeutic targets for NS as well as candidate genes for AD and atopy.
Journal of Experimental Medicine 06/2009; 206(5):1135-47. · 13.21 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: LEKTI is a 15-domain serine proteinase inhibitor whose defective expression underlies the severe autosomal recessive ichthyosiform skin disease, Netherton syndrome. Here, we show that LEKTI is produced as a precursor rapidly cleaved by furin, generating a variety of single or multidomain LEKTI fragments secreted in cultured keratinocytes and in the epidermis. The identity of these biological fragments (D1, D5, D6, D8-D11, and D9-D15) was inferred from biochemical analysis, using a panel of LEKTI antibodies. The functional inhibitory capacity of each fragment was tested on a panel of serine proteases. All LEKTI fragments, except D1, showed specific and differential inhibition of human kallikreins 5, 7, and 14. The strongest inhibition was observed with D8-D11, toward KLK5. Kinetics analysis revealed that this interaction is rapid and irreversible, reflecting an extremely tight binding complex. We demonstrated that pH variations govern this interaction, leading to the release of active KLK5 from the complex at acidic pH. These results identify KLK5, a key actor of the desquamation process, as the major target of LEKTI. They disclose a new mechanism of skin homeostasis by which the epidermal pH gradient allows precisely regulated KLK5 activity and corneodesmosomal cleavage in the most superficial layers of the stratum corneum.
Molecular Biology of the Cell 10/2007; 18(9):3607-19. · 4.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: SPINK5 (serine protease inhibitor Kazal-type 5), encoding the protease inhibitor LEKTI (lympho-epithelial Kazal-type related inhibitor), is the defective gene in Netherton syndrome (NS), a severe inherited keratinizing disorder. We have recently demonstrated epidermal protease hyperactivity in Spink5(-/-) mice resulting in desmosomal protein degradation. Herein, we investigated the molecular mechanism underlying the epidermal defect in 15 patients with NS. We demonstrated that, in a majority of patients, desmoglein 1 (Dsg1) and desmocollin 1 (Dsc1) were dramatically reduced in the upper most living layers of the epidermis. These defects were associated with premature degradation of corneodesmosomes. Stratum corneum tryptic enzyme (SCTE)-like and stratum corneum chymotryptic enzyme (SCCE)-like activities were increased, suggesting that these proteases participate in the premature degradation of corneodesmosomal cadherins. SCTE and SCCE expression was extended to the cell layers where Dsg1 and Dsc1 immunostaining was reduced. In contrast, a subset of six patients with normal epidermal protease activity or residual LEKTI expression displayed apparently normal cadherin expression and less severe disease manifestations. This suggests a degree of correlation between cadherin degradation and clinical severity. This work further supports the implication of premature corneodesmosomal cadherin degradation in the pathogenesis of NS and provides evidence for additional factors playing a role in disease expression.
Journal of Investigative Dermatology 08/2006; 126(7):1622-32. · 6.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lympho-epithelial Kazal-type-related inhibitor (LEKTI) is a putative serine protease inhibitor encoded by serine protease inhibitor Kazal-type 5 (SPINK5). It is strongly expressed in differentiated keratinocytes in normal skin but expression is markedly reduced or absent in Netherton syndrome (NS), a severe ichthyosis caused by SPINK5 mutations. At present, however, both the precise intracellular localization and biological roles of LEKTI are not known. To understand the functional role of LEKTI, we examined the localization of LEKTI together with kallikrein (KLK)7 and KLK5, possible targets of LEKTI, in the human epidermis, by confocal laser scanning microscopy and immunoelectron microscopy. In normal skin, LEKTI, KLK7, and KLK5 were all found in the lamellar granule (LG) system, but were separately localized. LEKTI was expressed earlier than KLK7 and KLK5. In NS skin, LEKTI was absent and an abnormal split in the superficial stratum granulosum was seen in three of four cases. Collectively, these results suggest that in normal skin the LG system transports and secretes LEKTI earlier than KLK7 and KLK5 preventing premature loss of stratum corneum integrity/cohesion. Our data provide new insights into the biological functions of LG and the pathogenesis of NS.
Journal of Investigative Dermatology 03/2005; 124(2):360-6. · 6.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mutations in SPINK5, encoding the serine protease inhibitor LEKTI, cause Netherton syndrome, a severe autosomal recessive genodermatosis. Spink5(-/-) mice faithfully replicate key features of Netherton syndrome, including altered desquamation, impaired keratinization, hair malformation and a skin barrier defect. LEKTI deficiency causes abnormal desmosome cleavage in the upper granular layer through degradation of desmoglein 1 due to stratum corneum tryptic enzyme and stratum corneum chymotryptic enzyme-like hyperactivity. This leads to defective stratum corneum adhesion and resultant loss of skin barrier function. Profilaggrin processing is increased and implicates LEKTI in the cornification process. This work identifies LEKTI as a key regulator of epidermal protease activity and degradation of desmoglein 1 as the primary pathogenic event in Netherton syndrome.