Search

Toxic epidermal necrolysis (TEN) is a fatal drug-induced skin reaction triggered by common medications and is an emerging public health issue1–3. Patients with TEN undergo severe and sudden epidermal detachment caused by keratinocyte cell death. Although molecular mechanisms that drive keratinocyte cell death have been proposed, the main drivers remain unknown, and there is no effective therapy for TEN4–6. Here, to systematically map molecular changes that are associated with TEN and identify potential druggable targets, we utilized deep visual proteomics, which provides single-cell-based, cell-type-resolution proteomics7,8. We analysed formalin-fixed, paraffin-embedded archived skin tissue biopsies of three types of cutaneous drug reactions with varying severity and quantified more than 5,000 proteins in keratinocytes and skin-infiltrating immune cells. This revealed a marked enrichment of type I and type II interferon signatures in the immune cell and keratinocyte compartment of patients with TEN, as well as phosphorylated STAT1 activation. Targeted inhibition with the pan-JAK inhibitor tofacitinib in vitro reduced keratinocyte-directed cytotoxicity. In vivo oral administration of tofacitinib, baricitinib or the JAK1-specific inhibitors abrocitinib or upadacitinib ameliorated clinical and histological disease severity in two distinct mouse models of TEN. Crucially, treatment with JAK inhibitors (JAKi) was safe and associated with rapid cutaneous re-epithelialization and recovery in seven patients with TEN. This study uncovers the JAK/STAT and interferon signalling pathways as key pathogenic drivers of TEN and demonstrates the potential of targeted JAKi as a curative therapy.

Acute generalized exanthematous pustulosis (AGEP) is a severe adverse cutaneous drug reaction. Although an involvement of drug-specific T cells has been reported, the physiopathology of AGEP and mechanism of neutrophilic skin inflammation remain incompletely understood. Recently, mutations in IL-36RN, the gene encoding the IL-36 receptor antagonist, have been reported to be more frequent in AGEP patients and pustular psoriasis. Here, we show that IL-36 cytokines, in particular IL-36γ, are highly expressed in lesional skin of AGEP patients, keratinocytes and macrophages being a major source of IL-36γ. Such an IL-36γ overexpression was not observed in patients with drug-induced maculopapular rash. In vitro, the causative drug specifically induced IL-36γ release either directly by the patient’s peripheral blood monocytes or indirectly by keratinocytes in the presence of autologous peripheral blood mononuclear cells. Such culprit drug induction of IL-36γ secretion in vitro was specific for AGEP and involved toll-like receptor 4 sensing the drug/albumin complex as a danger signal. Our results suggest that IL-36γ secretion by monocytes/macrophages and keratinocytes in response to culprit drug exposure likely plays a key role in the pathogenesis of AGEP.

We previously developed a drug-induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) severity (DDS) score that may predict DIHS/DRESS-associated complications (DACs), including myocarditis, gastrointestinal bleeding, and autoimmune diseases.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening, severe mucocutaneous adverse reactions. Severity prediction at early onset is urgently required for treatment. However, previous prediction scores have been based on data of blood tests.

OBJECTIVE: To analyze the relationship between clinical benefits and immunological changes in patients with systemic sclerosis (SSc) treated with autologous hematopoietic stem cell transplantation (HSCT). METHODS: Ten patients with SSc were treated with high-dose cyclophosphamide followed by highly purified CD34+ cells (n = 5) or unpurified grafts (n = 5). Two groups of patients were retrospectively constituted based on their clinical response (good responders, n = 7; and poor responders, n = 3). As well as clinical findings, immunological reconstitution through autologous HSCT was assessed by fluorescence-activated cell sorter analysis, quantification of signal joint T cell receptor rearrangement excision circles (sjTREC), reflecting the thymic function, and foxp3, a key gene of regulatory T cells, mRNA levels. RESULTS: Patients’ clinical and immunological findings were similar between good and poor responders, or CD34-purified and unpurified groups at inclusion. The sjTREC values were significantly suppressed at 3 months after autologous HSCT in good responders compared with poor responders (p = 0.0152). Reconstitution of CD4+CD45RO– naive T cells was delayed in good responders compared with poor responders. The phenotype of other lymphocytes, cytokine production in T cells, and foxp3 gene expression levels after autologous HSCT did not correlate with clinical response in good or poor responders. Clinical and immunological findings after autologous HSCT were similar between CD34-purified and unpurified groups. CONCLUSION: Our results suggest that immunosuppression intensity, sufficient to induce transient suppression of thymic function, is attributable to the feasible clinical response in patients with SSc treated with autologous HSCT. Appropriate monitoring of sjTREC values may predict clinical benefits in transplanted SSc patients after autologous HSCT.

Several lines of evidence have demonstrated that various cancers are derived from cancer stem cells (CSCs), which are thought to originate from either tissue stem or progenitor cells. However, recent studies have suggested that the origin of CSCs could be bone marrow-derived cells (BMDCs); for example, gastric cancer, which follows persistent gastric inflammation, appears to originate from BMDCs. Although our previous research showed the capability of BMDCs to differentiate into epidermal keratinocytes, it has yet to be determined whether skin CSCs originate from BMDCs. To assess the possibility that BMDCs could be the origin of CSCs in skin squamous cell carcinoma (SCC), we used a mouse model of UVB-induced skin SCC. We detected a low percentage of BMDCs in the lesions of epidermal dysplasia (0.59%), SCC in situ(0.15%), and SCC (0.03%). Furthermore, we could not find any evidence of clonal BMDC expansion. In SCC lesions, we also found that most of the BMDCs were tumor-infiltrating hematopoietic cells. In addition, BMDCs in the SCC lesions lacked characteristics of epidermal stem cells, including expression of stem cell markers (CD34, high α6 integrin) and the potential retention of BrdU label. These results indicate that BMDCs are not a major source of malignant keratinocytes in UVB-induced SCC. Therefore, we conclude that BMDCs are not the origin of CSCs in UVB-induced SCC.

Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS) is one example of a severe delayed T-cell–mediated adverse drug reaction. DIHS/DRESS presents with fever, widespread rash and facial edema, organ involvement, and hematological abnormalities, including eosinophilia and atypical lymphocytosis. DIHS/DRESS is associated with relapse 2 to 4 weeks after acute symptoms, often coinciding with reactivation of prevalent chronic persistent human herpesviruses such as human herpesvirus 6, EBV, and cytomegalovirus. The mortality of DIHS/DRESS is up to 10% and often related to unrecognized myocarditis and cytomegalovirus complications, with longer-term consequences that contribute to morbidity including autoimmune diseases such as thyroiditis. It is essential that all potential drug causes, including all new drugs introduced within the 8 weeks preceding onset of DIHS/DRESS symptoms, are identified. All potential drug culprits, as well as drugs that are closely related structurally to the culprit drug, should be avoided in the future. Systemic corticosteroids have remained the mainstay for the treatment of DIHS/DRESS with internal organ involvement. Steroid-sparing agents, such as cyclosporine, mycophenolate mofetil, and monthly intravenous immune globulin, have been successfully used for treatment, and careful follow-up for cytomegalovirus reactivation is recommended. Strong associations between HLA class I alleles and DIHS/DRESS predisposition include HLA-B∗13:01 and dapsone, HLA-B∗58:01 and allopurinol, and HLA-B∗32:01 and vancomycin. These have opened a pathway for prevention, risk stratification, and earlier diagnosis. Single-cell sequencing and other studies of immunopathogenesis promise to identify targeted treatment approaches.

Inherited tooth enamel hypoplasia occurs due to mutations in genes that encode major enamel components. Enamel hypoplasia also has been reported in junctional epidermolysis bullosa, caused by mutations in the genes that encode type XVII collagen (COL17), a component of the epithelial-mesenchymal junction. To elucidate the pathological mechanisms of the enamel hypoplasia that arise from the deficiency of epithelial-mesenchymal junction molecules, such as COL17, we investigated tooth formation in our recently established Col17−/−and Col17rescued mice. Compared with wild-type mice, the incisors of the Col17−/−mice exhibited reduced yellow pigmentation, diminished iron deposition, delayed calcification, and markedly irregular enamel prisms, indicating the presence of enamel hypoplasia. The molars of the Col17−/−mice demonstrated advanced occlusal wear. These abnormalities were corrected in the Col17rescued humanized mice. Thus, the Col17−/−mice clearly reproduced the enamel hypoplasia in human patients with junctional epidermolysis bullosa. We were able to investigate tooth formation in the Col17−/−mice because the Col17−/−genotype is not lethal. Col17−/−mouse incisors had poorly differentiated ameloblasts that lacked enamel protein-secreting Tomes' processes and reduced mRNA expression of amelogenin, ameloblastin, and of other enamel genes. These findings indicated that COL17 regulates ameloblast differentiation and is essential for normal formation of Tomes' processes. In conclusion, COL17 deficiency disrupts the epithelial-mesenchymal interactions, leading to both defective ameloblast differentiation and enamel malformation.

Angiogenesis is a complex process which is critical for the growth, invasion, and metastasis of tumors. In the past ten years numerous new agents have been developed as angiogenesis inhibitors. Angiogenesis inhibitors can be classified by their targeted area of the angiogenic process; (1) VEGF and its receptors VEGFR (e.g. Bevacizumab); (2) tyrosine kinases within endothelial cells (Sunitinib); (3) proliferation of endothelial cells (Endostatin); (4) MMPs (Marimastat); (5) intercellular interactions via integrins (Cilengitide) and (6) combinations of the above mechanisms (Thalidomide). Some showed anti-tumor effects with objective responses and stable disease, and some disappeared from clinical use due to unexpected side effects or insufficient efficacies. Further investigations of combined therapies including angiogenesis inhibitors will shed light on the treatment of advanced and metastasized malignancies.

Pigment epithelium-derived factor (PEDF) has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, and is involved in the pathogenesis of angiogenic eye disease such as proliferative diabetic retinopathy. However, a functional role for PEDF in tumor growth and angiogenesis remains to be determined. Melanoma is one of the most highly invasive and metastatic tumors. Malignant Melanoma is an increasingly common malignancy and also one the most invasive and metastatic tumors, and its mortality rates have been rapidly increasing above those of any other cancer in recent years. Surgical resection and systemic chemotherapy are the main therapeutic strategies for the treatment of malignant melanoma. However, these approaches are insufficiently effective and may be associated with significant adverse effects. Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries, is required for tumors to grow, invade and metastasize. Tumor vessels are genetically stable, and less likely to accumulate mutations that allow them to develop drug resistance in a rapid manner. Therefore, targeting vasculatures that support tumor growth, rather than cancer cells, is currently considered the most promising approach to malignant melanoma therapy. Now, novel anti-angiogenic agents with tolerable side effects are actually desired for the treatment of patients with malignant melanoma. In this paper, we review the current understanding of anti-angiogenic therapy for malignant melanoma, especially focusing on PEDF, which was recently identified as the most potent endogenous inhibitor of angiogenesis in the mammalian eye.

Recent clinical studies have reported an increased risk for various types of cancers in patients with diabetes. Diabetes is characterized by increased oxidative stress conditions. Hyperglycemia induces oxidative stress generation in a variety of cells via various metabolic pathways, thus causing oxidative DNA damage, an initial step of carcinogenesis. There is accumulating evidence that advanced glycation end products (AGE), senescent macroprotein derivatives formed at an accelerated rate under normal aging process and diabetes, are involved in the development and progression of cancers. AGE stimulate oxidative stress generation through the interaction with a receptor for AGE (RAGE), while oxidative stress generation promotes the formation of AGE and increases the expression of RAGE. These findings suggest that the crosstalk between the AGE-RAGE system and oxidative stress generation may form a positive feedback loop, thus further increasing the risk for cancers in patients with diabetes. This paper reviews current knowledge about the role of AGE-RAGE system in the development of various types of cancers.

Malignant melanoma is one of the most highly invasive and metastatic tumors. Melanoma is an increasingly common malignancy as well, and its mortality rates have been rapidly increasing above those of any other cancer in recent years. Surgical resection and systemic chemotherapy are the main therapeutic strategies for the treatment of malignant melanoma. However, these approaches are insufficiently effective and may be associated with significant adverse effects. Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries, is required for tumors to grow, invade and metastasize. Tumor vessels are genetically stable, and less likely to accumulate mutations that allow them to develop drug resistance in a rapid manner. Therefore, targeting vasculatures that support tumor growth, rather than cancer cells, is considered the most promising approach to malignant melanoma therapy. Now, novel anti-angiogenic agents with tolerable side effects is actually desired for the treatment of patients with malignant melanoma. In this paper, we review the current understanding of anti-angiogenic therapy for malignant melanoma, especially focusing on pigment epithelium-derived factor (PEDF), which was recently identified as the most potent endogenous inhibitor of angiogenesis in the mammalian eye. We also discuss here the involvement of a receptor for advanced glycation end products (RAGE) in angiogenesis, melanoma growth and metastasis, and the therapeutic implications of the blockers of RAGE in this devastating disorder.

Melanin, which is responsible for virtually all visible skin, hair, and eye pigmentation in humans, is synthesized, deposited, and distributed in subcellular organelles termed melanosomes. A comprehensive determination of the protein composition of this organelle has been obstructed by the melanin present. Here, we report a novel method of removing melanin that includes in-solution digestion and immobilized metal affinity chromatography (IMAC). Together with in-gel digestion, this method has allowed us to characterize melanosome proteomes at various developmental stages by tandem mass spectrometry. Comparative profiling and functional characterization of the melanosome proteomes identified ~1500 proteins in melanosomes of all stages, with ~600 in any given stage. These proteins include 16 homologous to mouse coat color genes and many associated with human pigmentary diseases. Approximately 100 proteins shared by melanosomes from pigmented and nonpigmented melanocytes define the essential melanosome proteome. Proteins validated by confirming their intracellular localization include PEDF (pigment-epithelium derived factor) and SLC24A5 (sodium/potassium/calcium exchanger 5, NCKX5). The sharing of proteins between melanosomes and other lysosome-related organelles suggests a common evolutionary origin. This work represents a model for the study of the biogenesis of lysosome-related organelles.

Atopic dermatitis is a chronic inflammatory skin disorder that often involves some ophthalmic features. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that is associated with the generation of cell-mediated immune responses. Although serum MIF levels may be elevated in severe atopic dermatitis, the quantity of MIF in regional ocular fluid remains unknown. We measured MIF levels in tears (lacrimal fluid) of patients with atopic dermatitis. Tear samples were collected from 16 patients with atopic dermatitis, 10 patients with allergic conjunctivitis, and 15 healthy control subjects. The clinical severity of atopic dermatitis was evaluated according to the Scoring Atopic Dermatitis (SCORAD) index. The index was calculated by summing the following scores: extent criteria, intensity criteria, and subjective symptoms. Macrophage migration inhibitory factor levels were determined by a human MIF enzyme-linked immunosorbent assay. All comparisons were two-tailed, and Pvalues <0.01 were considered as statistically significant.The mean MIF concentration in lacrimal fluid collected from healthy control subjects was 0.69±0.2 ng/ml. The mean tear MIF levels were 17.87±6.3 ng/ml in moderate-to-severe atopic dermatitis (SCORAD=15, P=0.002), 0.93±0.08 ng/ml in mild atopic dermatitis (SCORAD<15), and 2.76±0.86 ng/ml in allergic conjunctivitis (P=0.008).A proinflammatory cytokine MIF level was elevated in tears as well as serum in cases of severe atopic dermatitis. These results suggest that MIF may play an important role in the induction or enhancement of ophthalmic features related to severe atopic dermatitis.

Migration inhibitory factor (MIF) responds to tissue damage and regulates inflammatory and immunological processes. To elucidate the function of MIF in cutaneous wound healing, we analyzed MIF knockout (KO) mice. After the excision of wounds from the dorsal skin of MIF KO and wild-type (WT) mice, healing was significantly delayed in MIF KO mice compared to WT mice. Lipopolysaccharide treatment significantly increased [3H]thymidine uptake in WT mouse fibroblasts compared to MIF KO mouse fibroblasts. Furthermore, there was a significant reduction in fibroblast and keratinocyte migration observed in MIF KO mice after 1-oleoyl-2-lysophosphatidic acid treatment. We subsequently examined whether MIF-impregnated gelatin slow-release microbeads could accelerate skin wound healing. Injection of more than 1.5 μg/500 μl of MIF-impregnated gelatin microbeads around a wound edge accelerated wound healing compared to a single MIF injection without the use of microbeads. MIF-impregnated gelatin microbeads also accelerated skin wound healing in C57BL/6 mice and diabetic db/dbmice. Furthermore, incorporating MIF-impregnated gelatin microbeads into an artificial dermis implanted into MIF KO mice accelerated procollagen production and capillary formation. These findings suggest that MIF is crucial in accelerating cutaneous wound healing and that MIF-impregnated gelatin microbeads represent a promising treatment to facilitate skin wound healing.

Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries, is required for tumors to grow, invade, and metastasize. Vascular endothelial growth factor (VEGF), a specific mitogen to endothelial cells, is a crucial factor for tumor angiogenesis. In this study, we investigated whether minodronate, a newly developed nitrogen-containing bisphosphonate, could inhibit melanoma growth and improve survival in nude mice by suppressing the VEGF signaling. We found here that minodronate inhibited melanoma growth and improved survival in nude mice by suppressing the tumor-associated angiogenesis and macrophage infiltration. Minodronate completely inhibited the VEGF-induced increase in DNA synthesis and tube formation in endothelial cells by suppressing NADPH oxidase-mediated reactive oxygen species generation and Ras activation. Furthermore, minodronate inhibited the VEGF-induced expression of intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 in endothelial cells. Minodronate decreased DNA synthesis and increased apoptotic cell death of cultured melanoma cells as well. Our present study suggests that minodronate might suppress melanoma growth and improve survival in nude mice by two independent mechanisms; one is by blocking the VEGF signaling in endothelial cells, and the other is by inducing apoptotic cell death of melanoma. The present study provides a novel potential therapeutic strategy for the treatment of melanoma.

Pigment epithelium-derived factor (PEDF) has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, and is involved in the pathogenesis of angiogenic eye disease such as proliferative diabetic retinopathy. However, a functional role for PEDF in tumor growth and angiogenesis remains to be determined. In this study, we have investigated both the in vitroand in vivogrowth characteristics of human malignant melanoma G361 cell lines, stably transfected to overexpress human PEDF. Expression levels of PEDF proteins in melanoma cell lines G361 and A375 were comparable with that of human cultured melanocytes, whereas vascular endothelial growth factor levels in two tumor cell lines were much stronger than that in normal melanocytes. Overexpression of PEDF was found to significantly inhibit tumor growth and vessel formation in G361 nude mice xenografts. Furthermore, in vitroproliferation rates of G361 cells were decreased in PEDF-transfected cells. PEDF proteins showed dose-dependent induced growth retardation and apoptotic cell death in nontransfected G361 cells, which were completely prevented by treatment with antibodies against the Fas ligand. Our present study highlights two beneficial effects of PEDF treatment on melanoma growth and expansion; one is the suppression of tumor angiogenesis, and the other is induction of Fas ligand-dependent apoptosis in tumor cells. PEDF therefore might be a promising novel therapeutic agent for treatment of patients with melanoma.

The pathogeneses of toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS), both severe blistering diseases usually associated with drug intake, are not fully elucidated. Histologically, both TEN and SJS are characterized by extensive keratinocyte apoptosis. Previous studies have shown that keratinocyte apoptosis in TEN and SJS was induced by a suicidal interaction between Fas and Fas ligand (FasL), which are both expressed by keratinocytes. However, our preliminary examinations demonstrated that FasL is hardly detected on keratinocytes. We hypothesized that soluble FasL (sFasL) is secreted by peripheral blood mononuclear cells (PBMCs), and this interacts with the Fas expressed on keratinocytes in TEN and SJS. To justify this hypothesis, we investigated whether sFasL secreted by PBMCs could induce the keratinocyte apoptosis in TEN and SJS. Enzyme-linked immunosorbent assay analysis demonstrated that there was no significant sFasL increase in any samples of healthy controls (<40 pg/ml, n= 14) and patients with an ordinary erythema multiforme-type drug eruption (41.5 ± 3.1 pg/ml, n= 14), whereas high concentrations are detected in all samples of TEN and SJS patients (TEN: 131.5 ± 57.4 pg/ml, n= 8; SJS: 119.1 ± 41.0 pg/ml, n= 14) (P< 0.0001). In vitroanalysis using cultured keratinocytes revealed that the sera of TEN and SJS patients induced abundant keratinocyte apoptosis compared to erythema multiforme-type drug eruption sera. Furthermore, on stimulation with the causal drug, PBMCs obtained from TEN and SJS patients secreted high levels of sFasL. Taken together, these results indicate that sFasL secreted by PBMCs, not keratinocytes, plays a crucial role in the apoptosis and pathomechanism of TEN and SJS, and that the serum sFasL level may be a good indicator for the early diagnosis of TEN and SJS.

Angiogenesis is an ordered process requiring the inter‐play of numerous cellular and humoral factors. Studies over the past 20 years have identified several growth factors, cytokines, and enzymes that promote blood vessel formation. Most have revealed how individual factors promote an angiogenic phenotype in endothelial cells in vitro or contribute to blood vessel formation in vivo. However, the fundamental question that remains unanswered is how the cellular microenvironment contributes to angiogenesis. Fibrocytes are a recently characterized mesenchymal cell type isolated from peripheral blood that rapidly enter subcutaneously implanted wound chambers and sites of tissue injury. Here we describe the induction of an angiogenic phenotype in microvascular endothelial cells in vitro and promotion of angiogenesis in vivo by cultured fibrocytes. Fibrocytes constitutively secrete extracellular matrix‐degrading enzymes, primarily matrix metalloproteinase 9, which promotes endothelial cell invasion. In addition, fibrocytes secrete several proangiogenic factors including VEGF, bFGF, IL‐8, PDGF, and hematopoietic growth factors that promote endothelial cell migration, proliferation, and/or tube formation. By contrast, they do not produce representative antiangiogenic factors. Finally, both autologous fibrocytes and fibrocyte‐conditioned media were found to induce blood vessel formation in vivo using the Matrigel angiogenesis model.—Hartlapp, I., Abe, R., Saeed, R. W., Peng, T., Voelter, W., Bucala, R., Metz, C. N. Fibrocytes induce an angiogenic phenotype in cultured endothelial cells and promote angiogenesis in vivo. FASEB J.15, 2215–2224 (2001)

Neutrophil extracellular traps induced by drug-specific CD8+T cells initiate SJS/TEN.

Macrophage migration inhibitory factor (MIF) is known to function as a cytokine, hormone, and glucocorticoid-induced immunoregulator. In this study, we reported for the first time that human melanocytes and melanoma cells express MIF mRNA and produce MIF protein. Immunohistochemical analysis demonstrated that MIF was mostly localized in the cytoplasm of melanocytes and G361 cells, a widely available human melanoma cell line. In particular, strong positive staining was observed at the dendrites of these cells. Expression of MIF mRNA and production of MIF protein were much higher in human melanoma cells such as G361, A375, and L32 than in normal cultured melanocytes. To assess the role of MIF overexpression in melanoma cells, G361 cells were transfected with an antisense human MIF plasmid. The results demonstrated that the cell growth rate of the transfected cells was markedly suppressed, suggesting that MIF participates in the mechanism of proliferation of melanoma cells. To further evaluate the function of MIF, we employed the Boyden chamber method to examine the effect on tumor cell migration and found that MIF enhanced the migration of G361 cells in a dose-dependent manner. Furthermore, we administered anti-MIF antibody into tumor (G361 cells in a Millipore chamber)-bearing mice to assess the effect on tumor-associated angiogenesis. The anti-MIF antibody significantly suppressed tumor-induced angiogenesis. Taken together, these results indicated that it is likely that MIF may function as a novel growth factor that stimulates incessant growth and invasion of melanoma concomitant with neovascularization.

Macrophage migration inhibitory factor (MIF) is one of the immunoregulatory cytokines involved in T-cell activation and delayed-type hypersensitivity. To elucidate involvement of this cytokine in the pathogenesis of atopic dermatitis (AD), we examined serum MIF concentrations of patients with AD and non-atopic normal healthy individuals. The mean serum MIF concentration of the AD patients (n= 36) was 36.4 ± 3.7 ng/ml (mean ± SEM), whereas that of the non-atopic dermatitis patients (n= 17) or healthy individuals (n= 61) were 13.1 ± 1.8 or 6.5 ± 0.45 ng/ml, respectively. Accordingly, immunohistochemistry of the inflammatory skin lesion of an AD patient demonstrated that MIF protein was diffusely expressed throughout the whole epidermal layer. After 4-week steroid ointment treatment, the MIF concentration decreased as clinical symptoms improved. The serum level of TNF-α was also decreased in parallel with that of MIF. Considering the T-cell dysfunction and disordered cytokine-network reported in AD, it was strongly suggested that MIF was a critical protein for immunoregulation in the pathophysiological mechanism of AD. In this context, MIF may become a useful laboratory parameter to comprehend the clinical course of the disease.

Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) is a life-threatening cutaneous adverse drug reaction (cADR). Distinguishing SJS/TEN from nonsevere cADRs is difficult, especially in the early stages of the disease.

Circulating exosomal miR-375-3ppromotes keratinocyte apoptosis via XIAPrepression in Stevens-Johnson syndrome and toxic epidermal necrolysis.

Angiosarcoma is a rare malignant tumor derived from endothelial cells, and its prognosis is poor because advanced angiosarcoma is often resistant to taxane therapy. Endoglin (CD105) acts as a coreceptor for TGF-β signaling and is overexpressed in tumor-associated endothelial cells and enhances tumor angiogenesis. Numerous clinical trials are testing the effectiveness of anti-endoglin antibodies in various types of malignancies. Here, we investigated the role of endoglin in the pathogenesis of angiosarcoma and whether endoglin inhibition results in antitumor activity. Endoglin was overexpressed in angiosarcoma, and its inhibition was effective in promoting apoptosis and the suppression of migration, invasion, tube formation, and Warburg effect in angiosarcoma cells. Knockdown of endoglin activated caspase 3/7 that is essential for apoptosis, reduced survivin levels, and decreased paxillin and vascular endothelial cadherin phosphorylation and matrix metalloproteinase 2 and matrix metalloproteinase 9 activities in angiosarcoma cells. Although endoglin is a coreceptor that regulates TGF-β signaling, the antitumor effect of endoglin in angiosarcoma was not based on Smad signaling regulation but on non-Smad TGF-β signaling. Taken together, these results indicated that endoglin could be a novel therapeutic target for angiosarcoma.

Loss-of-function mutations in dystonin (DST) can cause hereditary sensory and autonomic neuropathy type 6 (HSAN-VI) or epidermolysis bullosa simplex (EBS). Recently, DST-related diseases were recognized to be more complex than previously thought because a patient exhibited both neurological and skin manifestations, whereas others display only one or the other. A single DST locus produces at least three major DST isoforms: DST-a (neuronal isoform), DST-b (muscular isoform) and DST-e (epithelial isoform). Dystonia musculorum (dt) mice, which have mutations in Dst, were originally identified as spontaneous mutants displaying neurological phenotypes. To reveal the mechanisms underlying the phenotypic heterogeneity of DST-related diseases, we investigated two mutant strains with different mutations: a spontaneous Dst mutant (Dstdt-23Rbrc mice) and a gene-trap mutant (DstGt mice). The Dstdt-23Rbrc allele possesses a nonsense mutation in an exon shared by all Dst isoforms. The DstGt allele is predicted to inactivate Dst-a and Dst-b isoforms but not Dst-e. There was a decrease in the levels of Dst-a mRNA in the neural tissue of both Dstdt-23Rbrc and DstGt homozygotes. Loss of sensory and autonomic nerve ends in the skin was observed in both Dstdt-23Rbrc and DstGt mice at postnatal stages. In contrast, Dst-e mRNA expression was reduced in the skin of Dstdt-23Rbrc mice but not in DstGt mice. Expression levels of Dst proteins in neural and cutaneous tissues correlated with Dst mRNAs. Because Dst-e encodes a structural protein in hemidesmosomes (HDs), we performed transmission electron microscopy. Lack of inner plaques and loss of keratin filament invasions underneath the HDs were observed in the basal keratinocytes of Dstdt-23Rbrc mice but not in those of DstGt mice; thus, the distinct phenotype of the skin of Dstdt-23Rbrc mice could be because of failure of Dst-e expression. These results indicate that distinct mutations within the Dst locus can cause different loss-of-function patterns among Dst isoforms, which accounts for the heterogeneous neural and skin phenotypes in dt mice and DST-related diseases.

We previously have found that advanced glycation end products (AGE), senescent macroproteins formed at an accelerated rate in diabetes, arise in vivonot only from glucose but also from reducing sugars. Furthermore, we recently have shown that glyceraldehyde‐ and glycolaldehyde‐derived AGE (glycer‐ and glycol‐AGE) are mainly involved in loss of pericytes, the earliest histopathological hallmark of diabetic retinopathy. However, the effects of these AGE proteins on angiogenesis, another vascular derangement in diabetic retinopathy, remain to be elucidated. In this study, we investigated whether these AGE proteins elicit changes in cultured endothelial cells that are associated with angiogenesis. When human skin microvascular endothelial cells (EC) were cultured with glycer‐AGE or glycol‐AGE, growth and tube formation of EC, the key steps of angiogenesis, were significantly stimulated. The AGE‐induced growth stimulation was significantly enhanced in AGE receptor (RAGE)‐overexpressed EC. Furthermore, AGE increased transcriptional activity of nuclear factor‐κB (NF‐κB) and activator protein‐1 (AP‐1) and then up‐regulated mRNA levels of vascular endothelial growth factor (VEGF) and angiopoietin‐2 (Ang‐2) in EC. Cerivastatin, a hydroxymethylglutaryl CoA reductase inhibitor; pyrrolidinedithiocarbamate; or curcumin was found to completely prevent the AGE‐induced increase in NF–κB and AP‐1 activity, VEGF mRNA up‐regulation, and the resultant increase in DNA synthesis in microvascular EC. These results suggest that the AGE‐RAGE interaction elicited angiogenesis through the transcriptional activation of the VEGF gene via NF‐κB and AP‐1 factors. By blocking AGE‐RAGE signaling pathways, cerivastatin might be a promising remedy for treating patients with proliferative diabetic retinopathy.

Inherited skin disorders have been reported recently to have sporadic normal-looking areas, where a portion of the keratinocytes have recovered from causative gene mutations (revertant mosaicism). We observed a case of recessive dystrophic epidermolysis bullosa treated with cultured epidermal autografts (CEAs), whose CEA-grafted site remained epithelized for 16 years. We proved that the CEA product and the grafted area included cells with revertant mosaicism. Based on these findings, we conducted an investigator-initiated clinical trial of CEAs from clinically revertant skin for recessive dystrophic epidermolysis bullosa. The donor sites were analyzed by genetic analysis, immunofluorescence, electron microscopy, and quantification of the reverted mRNA with deep sequencing. The primary endpoint was the ulcer epithelization rate per patient at 4 weeks after the last CEA application. Three patients with recessive dystrophic epidermolysis bullosa with 8 ulcers were enrolled, and the epithelization rate for each patient at the primary endpoint was 87.7%, 100%, and 57.0%, respectively. The clinical effects were found to persist for at least 76 weeks after CEA transplantation. One of the three patients had apparent revertant mosaicism in the donor skin and in the post-transplanted area. CEAs from clinically normal skin are a potentially well-tolerated treatment for recessive dystrophic epidermolysis bullosa.

The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system induces site-specific double-strand breaks, which stimulate cellular DNA repair through either the homologous recombination or non-homologous end-joining pathways. The non-homologous end-joining pathway, which is activated more frequently than homologous recombination, is prone to introducing small insertions and/or deletions at the double-strand break site, leading to changes in the reading frame. We hypothesized that the non-homologous end-joining pathway is applicable to genetic diseases caused by a frameshift mutation through restoration of the reading frame. Recessive dystrophic epidermolysis bullosa is a hereditary skin disorder caused by mutations in COL7A1. In this study, we applied gene reframing therapy to a recurrent frameshift mutation, c.5819delC, in COL7A1, which results in a premature termination codon. CRISPR/Cas9 targeting this specific mutation site was delivered to recessive dystrophic epidermolysis bullosa patient fibroblasts. After genotyping a large collection of gene-edited fibroblast clones, we identified a significant number (17/50) of clones in which the frameshift in COL7A1was restored. The reframed COL7 was functional, as shown by triple-helix formation assay in vitro, and was correctly distributed in the basement membrane zone in mice. Our data suggest that mutation site-specific non-homologous end-joining might be a highly efficient gene therapy for inherited disorders caused by frameshift mutations.

Annexin A1 secreted from drug-stimulated monocytes contributes to keratinocyte necroptosis in serious drug-related adverse events in skin.

In this decade, novel strategy against cancer, antiangiogeneic therapy, was attempted. A major microenvironmental event in tumor growth and expansion is the ‘angiogenic switch’, an alteration in the balance of pro-angiogenic and anti-angiogenic molecules that leads to tumor neovascularization. Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries or circulating endothelial ceslls, is required for tumors to grow, invade and metastasize. Tumor vessels are genetically quite stable, and less likely to accumulate mutations that allow them to develop drug resistance in a rapid manner. Therefore, targeting vasculature that supports tumor growth, rather than cancer cells themselves, is considered the most promising approach to cancer therapy. In this issue, we describe the possible antiangiogenesis basis of this therapeutic strategy. Circulating endothelial cell (CEC) and progenitor (CEP) number and viability are modulated in various pathological conditions including cancer. Martin-Padura and Bertolini [1] described CEC and CEP play an important role in cancer progression and metastasis. Indeed, emerging clinical data support that CEC and CEP kinetics and viability might predict the efficacy on anticancer drug combinations that include antiangiogenic agents. On the basis of these observations, CEC and CEP measurements have attractive potential diagnostic and therapeutic applications for malignant diseases. Among ‘angiogeneic cytokine’, macrophage migration inhibitor factor (MIF) is a highly conserved and evolutionarily ancient mediator with pleiotropic effects that has been implicated in tumor growth and progression. Bifulco et al. [2] reviewed MIFs function in multiple processes fundamental to tumorigenesis such as tumor proliferation, evasion of apoptosis, angiogenesis and invasion. These pleiotropic functional aspects are paralleled by MIFs unique signaling properties, which involve activation of the ERK-1/2 and AKT pathways. These properties reflect features central to growth regulation, apoptosis and cell cycle control than is typical for an immune cytokine. The significance of these pro-tumorigenic properties has found support in several in vitro and in vivo models of cancer and in the positive association between MIF production and tumor aggressiveness and metastatic potential in a variety of human tumors. Pigment epithelium-derived factor (PEDF) has recently been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, and is involved in the pathogenesis of angiogenic eye disease such as proliferative diabetic retinopathy. Abe et al. [3] reviewed a functional role for PEDF in tumor growth and angiogenesis. Recent studies reported the antitumor potential of PEDF in various cancer based on its antiangiogenic properties and PEDF direct inhibitory effect via tumor cell apoptosis. The discovery and evaluation of antiangiogenic substances initially relied on methods such as various models that use the cornea to assess blood vessel growth. Although they are important for understanding the mechanisms of blood vessel induction, these models do not represent tumor angiogenesis and are poorly suited to drug discovery. Amoh et al. [4] have utilized multicolored fluorescent proteins to develop imaging models of tumor angiogenesis, which are clinically-relevant imageable models to visualize and quantify angiogenesis and efficacy of inhibitors. Angiogenesis is a complex process which is critical for the growth, invasion, and metastasis of tumors. Fujita et al. [5] reviewed recent progress in this clinical filed. In the past ten years numerous new agents have been developed as angiogenesis inhibitors. Angiogenesis inhibitors can be classified by their targeted area of the angiogenic process; (1) VEGF and its receptors VEGFR (e.g. Bevacizumab); (2) tyrosine kinases within endothelial cells (Sunitinib); (3) proliferation of endothelial cells (Endostatin); (4) MMPs (Marimastat); (5) intercellular interactions via integrins (Cilengitide) and (6) combinations of the above mechanisms (Thalidomide). Some show anti-tumor effects with objective responses and stable disease, and some disappeared from clinical use due to unexpected side effects or insufficient efficacies. Further investigations of combined therapies including angiogenesis inhibitors will shed light on the treatment of advanced and metastasized malignancies.