TRPV3-Activated PARP1/AIFM1/MIF Axis through Oxidative Stress Contributes to Atopic Dermatitis.

TRPV3 is a temperature-sensitive calcium-permeable channel. In previous studies, we noticed prominent TUNEL-positive keratinocytes in patients with Olmsted syndrome and Trpv3+/G568V mice, both of which carry gain-of-function variants in the TRPV3 gene. However, it remains unclear how the keratinocytes die and whether this process contributes to more skin disorders. In this study, we showed that gain-of-function variant or pharmacological activation of TRPV3 resulted in poly(ADP-ribose) polymerase 1 (PARP1)/AIFM1/macrophage migration inhibitory factor axis-mediated parthanatos, which is an underestimated form of cell death in skin diseases. Chelating calcium, scavenging ROS, or inhibiting nitric oxide synthase effectively rescued the parthanatos, indicating that TRPV3 regulates parthanatos through calcium-mediated oxidative stress. Furthermore, inhibiting PARP1 downregulated TSLP and IL33 induced by TRPV3 activation in HaCaT cells, reduced immune cell infiltration, and ameliorated epidermal thickening in Trpv3+/G568V mice. Marked parthanatos was also detected in the skin of MC903-treated mice and patients with atopic dermatitis, whereas inhibiting PARP1 largely alleviated the MC903-induced dermatitis. In addition, stimulating parthanatos in mouse skin with methylnitronitrosoguanidine recapitulated many features of atopic dermatitis. These data demonstrate that the TRPV3-regulated parthanatos-associated PARP1/AIFM1/macrophage migration inhibitory factor axis is a critical contributor to the pathogenesis of Olmsted syndrome and atopic dermatitis, suggesting that modulating the PARP1/AIFM1/macrophage migration inhibitory factor axis is a promising therapy for these conditions.

Inhibition of Ca2+-permeable TRPV3 and inflammatory cytokine release by honokiol and magnolol in human epidermal keratinocytes.

Transient receptor potential vanilloid-3 (TRPV3) ion channels are prominently expressed in keratinocytes, playing a vital role in skin functions. Honokiol and magnolol (H&M) the primary bioactive constituents in Magnolia officinalis extract, demonstrate anti-inflammatory and skin-protective properties. Nevertheless, the underlying mechanism regarding their effect on Ca2+-permeable ion channels remain unclear. Our purpose in this study is to investigate the effect of H&M on TRPV3 and cytokine release in normal human epidermal keratinocytes (NHEKs), including its gain-of-function (GOF) mutants (G573S and G573C) associated with Olmstead syndrome. We performed whole-cell patch-clamp, fura-2 spectrofluorimetry to investigate channels activity, CCK-8 assay to analyze cell death and enzyme-linked immunosorbent assay to assess the cytokine release from NHEKs. H&M inhibited the TRPV3 current (ITRPV3) and cytosolic calcium increase in NHEKs, HEK293T cells overexpressing hTRPV3 and its GOF mutants. Moreover, the release of pro-inflammatory cytokines (interleukin-6 and -8) from keratinocytes stimulated by TRPV3 agonist was effectively suppressed by H&M. Our findings provide insights into the mechanism underlying the anti-inflammatory effects of H&M, highlighting their potential in treating skin diseases.

Novel Insights into the Role of Keratinocytes-Expressed TRPV3 in the Skin.

TRPV3 is a non-selective cation channel that is highly expressed in keratinocytes in the skin. Traditionally, keratinocytes-expressed TRPV3 is involved in multiple physiological and pathological functions of the skin, such as itching, heat pain, and hair development. Although the underlying mechanisms by which TRPV3 functions in vivo remain obscure, recent research studies suggest that several cytokines and EGFR signaling pathways may be involved. However, there have also been other studies with opposite results that question the role of TRPV3 in heat pain. In addition, an increasing number of studies have suggested a novel role of TRPV3 in promoting skin regeneration, indicating that TRPV3 may become a new potential target for regulating skin regeneration. This paper not only reviews the role of keratinocytes-expressed TRPV3 in the physiological and pathological processes of itching, heat pain, hair development, and skin regeneration, but also reviews the relationship between TRPV3 gene mutations and skin diseases such as atopic dermatitis (AD) and Olmsted syndrome (OS). This review will lay a foundation for further developing our understanding of the mechanisms by which TRPV3 is involved in itching, heat pain, and hair development, as well as the treatments for TRPV3-related skin diseases.

Two for two: Dual therapy with erlotinib and acitretin for twins with severe keratoderma in Olmsted syndrome.

Olmsted syndrome (OS) is a rare genetic disorder, characterized by painful palmoplantar keratoderma (PPK), periorificial and intertriginous hyperkeratoses, and alopecia. Fewer than 75 cases have been described. Variants in TRPV3 result in constitutive activation of transient receptor potential vanilloid 3, leading to increased epidermal growth factor receptor (EGFR) signaling, palmoplantar epidermal hyperproliferation, and exquisite lesional pain. We describe pre-school aged twins with OS with partial improvement from oral erlotinib, an EGFR inhibitor, but dramatic reduction of their persistent palmoplantar thickening and pain from adding acitretin.

An intronic splice-site variant in MBTPS2 underlies ichthyosis follicularis with atrichia and photophobia syndrome.

Ichthyosis follicularis with atrichia and photophobia (IFAP) syndrome is a rare genodermatosis characterized by a classic triad of follicular ichthyosis, alopecia, and photophobia. We report a Chinese patient displaying features of IFAP triad along with painful palmoplantar keratoderma, recurrent infections, periorificial keratotic plaques, nail dystrophy, and pachyonychia. Whole-exome sequencing revealed an intronic variant (NM_015884.3: exon7:c.970+5G>A) in the gene MBTPS2. Sanger sequencing confirmed that the variant segerated with phenotype in the family. Sequencing of cDNAs derived from the patient indicated the variant introduced a new splice donor site, leading to partial skipping of exon 7 (r.951_970del). An in vitro mini-gene assay also revealed abnormal splicing of exon 7. This study presents a case complicated with X-linked IFAP syndrome and Olmsted syndrome, and highlights the significance of using validation assays to identify the pathogenicity of intronic variants in MBTPS2.

Research Development in Patients with Olmsted Syndrome / 罕见病研究

Olmsted syndrome (OS) is an extremely rare hereditary skin disease, that is usually characterized by mutilating palmoplantar keratoderma (PPK) and periorificial keratotic plaques. The diagnosis of this disease depends primarily on the clinical presentation and OS has to be differentiated from other disorders associated with hyperkeratosis. In recent years, there have been many advances in molecular genetic research on the pathogenesis of the disease. The genes that can cause disease after specific mutations include TRPV3, MBTPS2/S2P and PERP. Therefore, genetic testing has become one of the important methods for the diagnosis of this disease.OS treatment is difficult, and conventional therapy uses topical drugs to soften the cuticle of the skin, or oral Avi A.Excision of palmoplantar keratosis may also be used for constricting rings that severely restrict movement, but they often reoccur after initial improvement. In terms of precision treatment, researchers have tried the small molecule drugs erlotinib and sirolimus and have achieved some results. This paper summarizes the etiology, pathogenesis, clinical manifestations, diagnosis, treatment and prognosis of OS, in order to improve the clinicans' awareness of OS.

Inhibition of temperature-sensitive TRPV3 channel by two natural isochlorogenic acid isomers for alleviation of dermatitis and chronic pruritus.

Genetic gain-of-function mutations of warm temperature-sensitive transient receptor potential vanilloid 3 (TRPV3) channel cause Olmsted syndrome characterized by severe itching and keratoderma, indicating that pharmacological inhibition of TRPV3 may hold promise for therapy of chronic pruritus and skin diseases. However, currently available TRPV3 tool inhibitors are either nonselective or less potent, thus impeding the validation of TRPV3 as therapeutic target. Using whole-cell patch-clamp and single-channel recordings, we report the identification of two natural dicaffeoylquinic acid isomers isochlorogenic acid A (IAA) and isochlorogenic acid B (IAB) that selectively inhibit TRPV3 currents with IC50 values of 2.7 ± 1.3 and 0.9 ± 0.3 µmol/L, respectively, and reduce the channel open probability to 3.7 ± 1.2% and 3.2 ± 1.1% from 26.9 ± 5.5%, respectively. In vivo evaluation confirms that both IAA and IAB significantly reverse the ear swelling of dermatitis and chronic pruritus. Furthermore, the isomer IAB is able to rescue the keratinocyte death induced by TRPV3 agonist carvacrol. Molecular docking combined with site-directed mutations reveals two residues T636 and F666 critical for the binding of the two isomers. Taken together, our identification of isochlorogenic acids A and B that act as specific TRPV3 channel inhibitors and gating modifiers not only provides an essential pharmacological tool for further investigation of the channel pharmacology and pathology, but also holds developmental potential for treatment of dermatitis and chronic pruritus.

Beyond Ca2+ signalling: the role of TRPV3 in the transport of NH4.

Mutations of TRPV3 lead to severe dermal hyperkeratosis in Olmsted syndrome, but whether the mutants are trafficked to the cell membrane or not is controversial. Even less is known about TRPV3 function in intestinal epithelia, although research on ruminants and pigs suggests an involvement in the uptake of NH4+. It was the purpose of this study to measure the permeability of the human homologue (hTRPV3) to NH4+, to localize hTRPV3 in human skin equivalents, and to investigate trafficking of the Olmsted mutant G573S. Immunoblotting and immunostaining verified the successful expression of hTRPV3 in HEK-293 cells and Xenopus oocytes with trafficking to the cell membrane. Human skin equivalents showed distinct staining of the apical membrane of the top layer of keratinocytes with cytosolic staining in the middle layers. Experiments with pH-sensitive microelectrodes on Xenopus oocytes demonstrated that acidification by NH4+ was significantly greater when hTRPV3 was expressed. Single-channel measurements showed larger conductances in overexpressing Xenopus oocytes than in controls. In whole-cell experiments on HEK-293 cells, both enantiomers of menthol stimulated influx of NH4+ in hTRPV3 expressing cells, but not in controls. Expression of the mutant G573S greatly reduced cell viability with partial rescue via ruthenium red. Immunofluorescence confirmed cytosolic expression, with membrane staining observed in a very small number of cells. We suggest that expression of TRPV3 by epithelia may have implications not just for Ca2+ signalling, but also for nitrogen metabolism. Models suggesting how influx of NH4+ via TRPV3 might stimulate skin cornification or intestinal NH4+ transport are discussed.

MBTPS2, a membrane bound protease, underlying several distinct skin and bone disorders.

The MBTPS2 gene on the X-chromosome encodes the membrane-bound transcription factor protease, site-2 (MBTPS2) or site-2 protease (S2P) which cleaves and activates several signaling and regulatory proteins from the membrane. The MBTPS2 is critical for a myriad of cellular processes, ranging from the regulation of cholesterol homeostasis to unfolded protein responses. While its functional role has become much clearer in the recent years, how mutations in the MBTPS2 gene lead to several human disorders with different phenotypes including Ichthyosis Follicularis, Atrichia and Photophobia syndrome (IFAP) with or without BRESHECK syndrome, Keratosis Follicularis Spinulosa Decalvans (KFSD), Olmsted syndrome, and Osteogenesis Imperfecta type XIX remains obscure. This review presents the biological role of MBTPS2 in development, summarizes its mutations and implicated disorders, and discusses outstanding unanswered questions.

Case of Olmsted Syndrome with Essential Thrombocytosis Misdiagnosed as Acrodermatitis Enteropathica.

Olmsted syndrome is a rare genodermatosis. Palmoplantar keratoderma and periorificial keratodermic plaques are the most important clinical findings. Additional findings associated with a large number of systems may accompany such as teeth, nail deformities, alopecia, mental retardation, and bone-joint anomalies. Therefore, it is difficult to make a differential diagnosis from other palmoplantar keratodermas. It also needs to be differentiated from acrodermatitis enteropathica because of periorificial plaques. The absence of regression in lesions with zinc treatment excludes this disease. We present here an Olmsted syndrome case with essential thrombocytosis for the first time.

Olmsted Syndrome with Lateral Supraciliary Madarosis and Clubbing: A Rare Case Report.

Olmsted syndrome (OS) is a rare congenital, mutilating palmoplantar keratoderma first described by Olmsted in 1927. It starts in the neonatal period or in childhood, and has a slow but progressive disabling course. We report the case of a 16-year-old boy who presented with keratoderma of the palm and soles since childhood with lateral supraciliary madarosis and clubbing. The patient was started on oral retinoids and topical keratolytics and had partial improvement in 2 months. Keratoderma of the palms and soles along with lateral supraciliary madarosis and clubbing in our case is a very rare finding, and to the best of our knowledge, has not been reported so far.

Olmsted Syndrome Caused by a Heterozygous p.Gly568Val Missense Mutation in TRPV3 Gene.

Olmsted syndrome (OS) is a rare congenital skin disorder characterized by severe palmoplantar and periorificial keratoderma, alopecia, onychodystrophy, and severe pruritus. Recently, pathogenic 'gain-of-function' mutations of the transient receptor potential vanilloid 3 gene (TRPV3), which encodes a cation channel involved in keratinocyte differentiation and proliferation, hair growth, inflammation, pain and pruritus, have been identified to cause OS. Due to the rarity, the pattern of inheritance of OS is still unclear. We report a case of OS in a 3-year-old Korean girl and its underlying gene mutation. The patient presented with a disabling, bilateral palmoplantar keratoderma with onychodystrophy. She also exhibited pruritic eczematous skin lesions around her eyes, ears and gluteal fold. Genetic analysis identified a heterozygous p.Gly568Val missense mutation in the exon 13 of TRPV3. To our knowledge, this is the first case of OS in the Korean population showing a missense mutation p.Gly573Ser.

Olmsted Syndrome Caused by a Heterozygous p.Gly568Val Missense Mutation in TRPV3 Gene

Olmsted syndrome (OS) is a rare congenital skin disorder characterized by severe palmoplantar and periorificial keratoderma, alopecia, onychodystrophy, and severe pruritus. Recently, pathogenic ‘gain-of-function‘ mutations of the transient receptor potential vanilloid 3 gene (TRPV3), which encodes a cation channel involved in keratinocyte differentiation and proliferation, hair growth, inflammation, pain and pruritus, have been identified to cause OS. Due to the rarity, the pattern of inheritance of OS is still unclear. We report a case of OS in a 3-year-old Korean girl and its underlying gene mutation. The patient presented with a disabling, bilateral palmoplantar keratoderma with onychodystrophy. She also exhibited pruritic eczematous skin lesions around her eyes, ears and gluteal fold. Genetic analysis identified a heterozygous p.Gly568Val missense mutation in the exon 13 of TRPV3. To our knowledge, this is the first case of OS in the Korean population showing a missense mutation p.Gly573Ser.

Mutilating Keratoderma with Concomitant Alopecia and Keratoses Follicularis Spinulosa Decalvans: X-Linked Olmsted Syndrome and its Response to Isotretinoin.

We report a case of mutilating keratoderma with alopecia and keratoses follicularis spinulosa decalvans (KFSD), which was initially diagnosed as ectodermal dysplasia and Olmsted syndrome but was revisited as a case of X-linked Olmsted (XLO) syndrome. We focus on this uncommon entity (XLO) to highlight the differentials of alopecia with palmoplantar keratoderma.

Identification of a heterozygous p.Gly568Val missense mutation in the TRPV3 gene in a Japanese patient with Olmsted syndrome: In silico analysis of TRPV3.

Olmsted syndrome is a very rare congenital disorder, characterized by palmoplantar keratoderma and periorificial keratotic lesions. Recently, TRPV3 was reported to be a causative gene of Olmsted syndrome. We identified a heterozygous missense mutation of TRPV3, c.1703G>T, p.Gly568Val, in a Japanese patient with Olmsted syndrome. To the best of our knowledge, this is the first report of a Japanese patient with Olmsted syndrome harboring a missense mutation in TRPV3. We conducted in silico analysis of TRPV3 to evaluate whether the p.Gly568Val leads to structural changes in the TRPV3 selectivity filter. The selectivity filter was shown to become dilated and hyperpermeable as a result of genetic mutation (p.Gly573Ser, p.Tr692Gly or p.Gly568Val) as well as after a change in temperature (300 K to 310 K). In silico analysis of TRPV3 could be a useful approach in predicting mutation-induced activated states of ion channels, and thus enrich our understanding of the pathogenesis of Olmsted syndrome.

Decreases in 15-lipoxygenase metabolites in Olmsted syndrome model rats.

BACKGROUND: Olmsted syndrome (OS) is a congenital dermatosis characterized by palmoplantar keratoderma and periorificial keratotic plaque. TRPV3 (transient receptor potential vanilloid subtype 3) encodes a thermosensitive Ca2+ channel and is the causative gene of OS. However, the molecular mechanism that causes the pathological development of OS is unclear. OBJECTIVE: We aimed to investigate the molecular mechanisms underlying OS pathology from the perspective of lipid metabolism. METHODS: Comprehensive lipidomics and microarray analyses were conducted on tissue samples from a non-lesional skin area of OS model rats (Ht rats) and from wild type (WT) rats as the control. RESULTS: Infiltration of leukocytes such as eosinophils and neutrophils and an increase in the fibrotic region were detected in the unaffected skin area of Ht rats compared with the WT rats. Among about 600 lipid species examined, the levels of 15-lipoxygenase (LOX) metabolites, the precursors of anti-inflammatory and pro-resolving lipid mediators, and dihydroceramides decreased by ≥16-fold in Ht rats compared with WT rats. Consistent with the decreases in the 15-LOX metabolites, expression levels of the genes that encode the 15-LOXs, Alox15 and Alox15b, were largely reduced. Conversely, increased expression levels were detected of Il36b, Ccl20, Cxcl1, and Cxcl2, which encode cytokines/chemokines, and S100a8 and S100a9, which encode the Ca2+ binding proteins that are implicated in epidermal proliferation. CONCLUSION: The pro-inflammatory state in the unaffected skin of Ht rats caused by decreases in 15-LOX metabolites and increases in cytokines/chemokines may contribute to the pathogenesis of OS.

TRPV3 mutants causing Olmsted Syndrome induce impaired cell adhesion and nonfunctional lysosomes.

TRPV3 is a non-selective cationic channel and is important for several physiological functions. It can be activated by physiological temperature and selective endogenous and exogenous compounds. TRPV3 is one of the key ion channel involved in Ca2+-signaling in keratinocyte and thus involved in skin-related functions. Recently, naturally occurring mutations in TRPV3, namely G573A, G573S, G573C and W692G have been detected which are linked with the development of pathophysiological conditions such as Olmsted Syndrome (OS) and other skin disorders. Our qualitative and quantitative data suggests that these naturally occurring TRPV3 mutants are mainly restricted in the ER. Expression of OS-mutants cause impaired vesicular trafficking resulting reduced surface localization of these mutants and other membrane proteins too. OS-mutants also cause reduced cell adhesion, altered distribution and less number of lysosomes. Our data confirms that TRPV3 is a lysosomal protein suggesting that Olmsted Syndrome is a lysosomal disorder. These findings may have a broad implication in the context of keratinocyte functions, skin-degeneration and in skin-cancer.