Effect of tannic acid on skin barrier function.

In this study, we investigated how tannic acid (TA) protects the skin from inflammation caused by external irritation. The effects of TA were evaluated using a mouse 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced skin inflammation model and a reconstructed human epidermal model. We then used Lucifer Yellow for visual confirmation of TA's suppression effect at the stratum corneum (SC) surface. TA treatment of the skin prevented Lucifer Yellow from permeating the skin. This result suggests that TA acts as a barrier against external stimulants such as TPA and artificial sweat on the SC surface.

Effects of different base agents on prediction of skin irritation by sodium lauryl sulfate using patch testing and repeated application test.

Animal testing for cosmetics was banned in the European Union (EU) in 2013; therefore, human tests to predict and ensure skin safety such as the patch test or usage test are now in demand in Japan as well as in the EU. In order to investigate the effects of different bases on the findings of tests to predict skin irritation, we performed patch testing (PT) and the repeated application test (RAT) using sodium lauryl sulfate (SLS), a well-known irritant, dissolved in 6 different base agents to examine the effects of these bases on skin irritation by SLS. The bases for PT were distilled water, 50% ethanol, 100% ethanol, a gel containing 50% ethanol, white petrolatum, and hydrophilic cream. The concentrations of SLS were 0.2% and 0.5%. Twelve different base combinations were applied to the normal back skin of 19 individuals for 24h. RAT was performed with distilled water, 50% ethanol, 100% ethanol, a gel containing 50% ethanol, white petrolatum, and hydrophilic cream containing SLS at concentrations of 0.2%, 2%, and 5%, being applied to the arms of the same PT subjects. The test preparation of each base was applied at the same site, with 0.2% SLS being used in the first week, 2% SLS in the following week, and 5% SLS in the final week. The results of PT revealed that skin irritation scores varied when SLS at the same concentration was dissolved in a different base. The results of RAT showed that although skin irritation appeared with every base at a concentration of 5%, the positive rate was approximately the same. In conclusion, our results suggest that skin irritation elicited in PT depends on the base, while in RAT, it does not depend on the type of base employed.

Glycyrrhetinic acid inhibits contact hypersensitivity induced by trichophytin via dectin-1.

Trichophyton infection is highly prevalent and tends to be recurrent. Therefore, it is important to develop new therapeutic agents. Previously, we established a mouse model of Trichophyton-induced contact hypersensitivity (CHS) and demonstrated that dectin-1 was involved in inflammation induced by trichophytin, the Trichophyton antigen. Here, we used that model to investigate glycyrrhetinic acid (GA) from plants of the genus Glycyrrhiza as a potential anti-inflammatory agent against superficial mycoses. GA suppressed swelling and the expression of inflammatory cytokines, including macrophage inflammatory protein (MIP)-2, interleukin (IL)-6, tumor necrosis factor (TNF)-α and interferon (IFN)-γ mRNA. Anti-MIP-2 antibody suppressed trichophytin-induced inflammation, and antidectin-1 antibody suppressed zymosan-induced MIP-2 production in keratinocyte cells. These results suggest that MIP-2 is produced by dectin-1 activation and is involved in inflammation associated with CHS to trichophytin. GA also suppressed zymosan-induced MIP-2 and interleukin (IL)-8, production in mouse and human macrophages and keratinocytes. Furthermore, GA suppressed the phosphorylation of spleen tyrosine kinase (Syk) and inhibitor of nuclear factor-kappa B (IκBα) and the degradation of IκBα in zymosan-simulated RAW264.7 cells. The results of this study suggest that GA suppresses inflammation induced by trichophytin, partly by the downregulation of Syk phosphorylation.

Optimal evaluation time point for patch testing to predict skin irritation of commercial topical drugs.

To develop patch testing (PT) that better reflects the skin irritation resulting from repeated applications, we methodically classified PT results and examined correlations between these results with results from repeated application tests. A total of 115 commercial topical drugs were used for patch testing. In two groups of 30 healthy individuals with normal back skin, 55 or 60 commercial topical drugs were applied to the back for 24 h. Skin reactions were scored for each group at 2 and 24 h after patch removal. Based on time-dependent changes in skin reaction at each evaluation time, PT results were classified into six different types. For repeated application testing, a total of 17 products with different types of PT results were selected. A total of 104 healthy individuals divided into three groups (n = 22-52 each) received application of 6-7 test materials, differing for each group, for 3 weeks on both arms. Incidences of positive symptoms induced by repeated drug application excluding transient erythema showed a greater correlation with reaction levels at 24 h after patch removal than 2 h after patch removal. Many test materials that triggered a high incidence of positive symptoms after repeated application also exhibited erythema or greater reaction up to 24 h after patch removal. PT offers a useful test system for predicting skin irritation that develops after repeated application of topical drug. Moreover, assessment at 24 h after patch removal is suggested as the optimal evaluation time point to reflect the results of repeated application tests.

Study of the usefulness of patch testing and use test to predict the safety of commercial topical drugs.

Patch testing (PT) can be used to identify allergens and irritants responsible for contact allergic and irritant dermatitis, respectively. However, the reproducibility of PT and correlation between PT and use test has not been fully evaluated. The aim of the present study was to examine the reproducibility of PT and its usefulness in assessing the safety of topical drugs. A total of 55 topical drugs were applied to the backs of two groups of subjects for either 24 or 48 h, and skin irritant reactions were graded at 2 and 24 h after patch removal. For the repeat open application test, six topical drugs with different irritation scores were applied to the arms of two groups of subjects twice daily for 3 weeks, and local symptoms were recorded. The mean irritation scores were similar between the two PT groups. The percentage of subjects positive for symptoms provoked by the use tests was similar between the two groups. The mean irritation scores 24 h after patch removal correlated with the skin symptoms provoked by the use test. PT was reproducible and the results correlated with the use test results. PT is a useful method for evaluating the safety of commercial topical drugs.

Analysis of Trichophyton antigen-induced contact hypersensitivity in mouse.

BACKGROUND: Trichophyton-induced superficial skin mycosis is a common infectious human disease, but the immunological mechanism against Trichophyton infection is unclear with regard to many points. Since Trichophyton cannot colonize mice, guinea pigs were used in previous experiments on Trichophyton infection. However, it is difficult to perform immunological and genetic analyses in guinea pigs. OBJECTIVE: The objective of this study was to establish a mouse Trichophytin-associated inflammation model of superficial skin mycosis in which immunological and genetic analyses can be performed. METHODS: We established a mouse Trichophyton-induced contact hypersensitivity model by applying Trichophytin, the Trichophyton antigen, extracted from Trichophyton mentagrophytes, to mice. Using a Th1-dominant strain, C57BL/6, and a Th2-dominant strain, BALB/c, we investigated the expression of inflammatory cytokines and receptors of the innate immune system for fungi, TLR4, TLR2, and dectin-1, and their influences on responses of the acquired immune system. RESULTS: In C57BL/6 mice, expressions of IFN-γ and IL-17 A in regional lymph nodes and IL-1ß, IFN-γ, IL-6, and IL-23 in the inflammatory auricular skin were enhanced by Trichophytin challenge, suggesting that not only Th1 cells but also Th17 cells were induced. In BALB/c mice, expressions of IL-4 in regional lymph nodes, and TSLP and IL-4 in the auricular skin were enhanced by Trichophytin challenge. Interestingly, dectin-1-neutralizing antibody inhibited the promotion of IFN-γ production in C57BL/6 mice, and dectin-1-expressing immune cells had crucial actions in Trichophyton-induced IFN-γ production. CONCLUSION: These results suggest that inflammatory mediators differently regulate Trichophytin-induced contact hypersensitivity on the basis of the status of host immunity.

Matrix proteins of basement membrane of intrahepatic bile ducts are degraded in congenital hepatic fibrosis and Caroli's disease.

Congenital hepatic fibrosis (CHF) and Caroli's disease are though to result from ductal plate malformation, and the basal laminar components play important roles in biliary differentiation during development. To clarify the involvement of basal laminar components in the ductal plate malformation, this study examined the immunohistochemical expression of laminin and type IV collagen in the livers of CHF and Caroli's disease. Using the polycystic kidney (PCK) rat, an animal model of Caroli's disease with CHF, in vivo and in vitro experiments were also performed. Immunostaining showed that basement membrane expression of laminin and type IV collagen around intrahepatic bile ducts was degraded in CHF, Caroli's disease, and the PCK rats. The degradation of laminin and type IV collagen around bile ducts was also observed in foci of cholangiocarcinoma in situ of Caroli's disease. In vitro, PCK cholangiocytes were found to overexpress plasminogen and a serine proteinase, the tissue-type plasminogen activator (tPA). When PCK cholangiocytes were cultured in Matrigel, the amounts of laminin and collagen in the gel were significantly reduced, and addition of alpha2-antiplasmin in the culture medium inhibited the degradation of laminin and collagen in Matrigel. These results suggest that biliary overexpression of plasminogen and tPA leads to the generation of excessive amounts of plasmin, and subsequent plasmin-dependent lysis of the extracellular matrix molecules may contribute to the biliary dysgenesis in CHF and Caroli's disease, including progressive cystic dilatation of the intrahepatic bile ducts in Caroli's disease. In addition, it is suggested that once cholangiocarcinoma in situ develops in the biliary epithelium of CHF and Caroli's disease, it tends to transform into invasive carcinoma, due to instability of the basement membrane of the bile ducts.

Cholangiocytes with mesenchymal features contribute to progressive hepatic fibrosis of the polycystic kidney rat.

The polycystic kidney (PCK) rat is an animal model of Caroli's disease with congenital hepatic fibrosis, in which the mechanism of progressive hepatic fibrosis remains unknown. This study aimed to clarify the mechanism of hepatic fibrosis of the PCK rat from the viewpoint of the contribution of pathological cholangiocytes. In liver sections of the PCK rats, intrahepatic bile ducts were constituted by two different phenotypes: bile ducts lined by cuboidal-shaped and flat-shaped cholangiocytes. The flat-shaped cholangiocytes showed reduced immunohistochemical expression of the biliary epithelial marker cytokeratin 19 and positive immunoreactivity for vimentin and fibronectin. When cultured cholangiocytes of the PCK rat were treated with transforming growth factor (TGF)-beta1, a potent inducer of epithelial-mesenchymal transition, induction of vimentin, fibronectin, and collagen expression occurred in the PCK cholangiocytes. Although the TGF-beta1 treatment reduced cytokeratin 19 expression, the epithelial cell features characterized by the expression of E-cadherin and zonula occludens-1 was maintained, and alpha-smooth muscle actin expression was not induced in the cholangiocytes. Cholangiocytes of the PCK rat may acquire mesenchymal features in response to TGF-beta1 and participate in progressive hepatic fibrosis by producing extracellular matrix molecules, which seems to be a different event from epithelial-mesenchymal transition.

Innate immune response to double-stranded RNA in biliary epithelial cells is associated with the pathogenesis of biliary atresia.

UNLABELLED: Infections of Reoviridae consisting of a double-stranded RNA (dsRNA) genome are a possible cause of biliary atresia (BA). The aim of the present study is to clarify the pathophysiological function of dsRNA viruses in the pathogenesis of BA. The expression of dsRNA pattern-recognizing receptors, Toll-like receptor 3 (TLR3), retinoic acid inducible gene I (RIG-I), melanoma differentiation-associated gene-5 (MDA-5), and dsRNA-activated protein kinase R (PKR) was constitutively detected in cultured human biliary epithelial cells (BECs). Stimulation with polyinosinic-polycytidylic acid [poly(I:C), a synthetic analog of viral dsRNA] induced the activation of transcription factors [nuclear factor (NF)-kappaB and interferon regulatory factor 3 (IRF3)] and the production of interferon-beta1 (IFN-beta1) and MxA as potent antiviral responses. Moreover, poly(I:C) up-regulated the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and both poly(I:C) and TRAIL reduced the viability of cultured human BECs by enhancing apoptosis. Experiments in vivo using tissue sections of extrahepatic bile ducts from patients with BA and controls (choledochal cysts and nonbiliary diseases) showed that the activation of NF-kappaB, interferon regulatory factor-3 (IRF-3), and PKR, and the enhancement of TRAIL and single-stranded DNA (ssDNA)-positive apoptosis were significant in BA, although extrahepatic bile ducts diffusely and constantly expressed TLR3 in all diseases. CONCLUSION: dsRNA viruses could directly induce the expression of TRAIL and apoptosis in human biliary epithelial cells as a result of the biliary innate immune response, supporting the notion that Reoviridae infections are directly associated with the pathogenesis of cholangiopathies in cases of BA.

Inhibition of intrahepatic bile duct dilation of the polycystic kidney rat with a novel tyrosine kinase inhibitor gefitinib.

The polycystic kidney (PCK) rat represents a liver and kidney cyst pathology corresponding to Caroli's disease with congenital hepatic fibrosis and autosomal recessive polycystic kidney disease. We previously reported that an epidermal growth factor receptor tyrosine kinase inhibitor, gefitinib (Iressa), significantly inhibited the abnormal growth of biliary epithelial cells of PCK rats in vitro. This study investigated the effects of gefitinib on cyst pathogenesis of the PCK rat both in vitro and in vivo. A three-dimensional culture model of biliary epithelial cells in the collagen gel matrix was used for in vitro analysis. For in vivo experiments, PCK and control rats were treated with gefitinib between 3 and 10 weeks of age. In vitro, gefitinib had strong inhibitory effects on biliary cyst formation of PCK rats. In vivo, treatment with gefitinib significantly inhibited the cystic dilatation of the intrahepatic bile ducts of PCK rats, which was accompanied by improvement of liver fibrosis. By contrast, no beneficial effects were observed on renal cyst development because of the treatment. These results suggest that signaling pathways mediated by epidermal growth factor receptor are involved in biliary dysgenesis of the PCK rat, with the mechanisms of cyst progression being different between the liver and kidney.

Diffuse expression of heparan sulfate proteoglycan and connective tissue growth factor in fibrous septa with many mast cells relate to unresolving hepatic fibrosis of congenital hepatic fibrosis.

BACKGROUND AND AIMS: Congenital hepatic fibrosis (CHF) is characterized by dense portal/septal fibrosis and bile duct proliferation and tortuosity. In this study, the roles and significance of fibrosis-related cells and molecules in the process of progressive and unresolving fibrosis of CHF were examined in comparison with other fibrotic liver diseases. METHODS: Seven CHF livers were examined, and a total of 74 control livers (chronic viral hepatitis (CVH), alcoholic fibrosis/cirrhosis (F/C), extrahepatic biliary obstruction and livers showing non-specific reactive changes) were used as controls. All of these livers were wedge biopsied or surgically resected ones, and were formalin fixed and paraffin embedded. In addition to histologic observations, expression of heparan sulfate proteoglycan (HSPG), connective tissue growth factor (CTGF), mast cell-specific tryptase, alpha-smooth muscle actin for activated hepatic stellate cells (HSC) or myofibroblasts (MF) were immunohistochemically surveyed. HSPG and CTGF at mRNA were also examined by in situ hybridization. RESULTS: Portal/septal fibrosis of CHF were mature collagenous and elastic fiber poor, when compared with controls. HSPG and CTGF were diffusely abundant in fibrous portal tracts/septa in CHF, while they were more or less accentuated at periportal areas in alcoholic F/C and CVH. In CHF, the number of interface and portal/septal MF was increased from mild-to-moderate degree, while their increase was moderate to marked in alcoholic F/C and CVH, particularly F3/F4. While activated HSC were frequent in alcoholic F/C and CVH and they were continuous with interface MF, activated HSC in CHF were scanty. Instead, mast cells were increased in portal/septal fibrosis of CHF. Portal mononuclear cells and endothelial cells were positive for HSPG mRNA, and mononuclear cells for CTGF mRNA, and such cells were accentuated around proliferated bile ducts and ductules in CHF. CONCLUSIONS: Abundant CTGF retained diffusely in HSPG in the fibrous portal tracts/septa may be responsible for non-resolving hepatic fibrosis in CHF, and many mast cells and portal MF not related to HSC may causally relate to such characteristic finding in CHF.

Activation of the MEK5/ERK5 cascade is responsible for biliary dysgenesis in a rat model of Caroli's disease.

Polycystic kidney (PCK) rats exhibit a multiorgan cyst pathology similar to human autosomal recessive polycystic kidney disease, and are proposed as an animal model of Caroli's disease with congenital hepatic fibrosis (CHF). This study investigated the expression and function of selected components of the mitogen activated protein kinase (MAPK) pathway in cultured intrahepatic biliary epithelial cells (BECs) of PCK rats. Compared to the proliferative activity of cultured BECs of control rats, those of the PCK rats were hyperresponsive to epidermal growth factor (EGF). The increase in BEC proliferation was accompanied by overexpression of MAPK/extracellular signal-regulated protein kinase (ERK) kinase 5 (MEK5), and subsequent phosphorylation of ERK5 in vitro. The increased proliferative activity was significantly inhibited by the transfection of short interfering RNA against MEK5 mRNA. An EGF receptor tyrosine kinase inhibitor, gefitinib ("Iressa", ZD1839), also significantly inhibited the abnormal growth of cultured BECs of PCK rats. By contrast, treatment with PD98059 and U0126, inhibitors for MEK1/2, was less effective. These results suggest that the activation of the MEK5-ERK5 cascade plays a pivotal role in the biliary dysgenesis of PCK rats, and also provide insights into the pathogenesis of Caroli's disease with CHF. As the MEK5-ERK5 interaction is highly specific, it may represent a potential target of therapy.

Type1 and type2 memory T cells imbalance shown by expression of intrahepatic chemokine receptors relates to pathogenesis of primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is characterized by the immunopathologic destruction of interlobular bile ducts. Generally, immunereaction induced by the antigenetic stimulation is divided to cellular and humoral reactions, which are regulated by type1 and type2 memory T cells, respectively. The relative strength of type1 and type2 responses is an important factor in the pathophysiology of immune-mediated diseases. Chemokine receptors are disproportionally expressed in type1 and type2 T cells, providing a basis for tissue-specific recruitment of helper and cytotoxic T cell subsets. In this study, the expression of CXC chemokine receptor 3 (CXCR3) and CC chemokine receptor 4 (CCR4), which are preferentially expressed on type1 and type2, respectively, were examined to clarify their imbalance in the PBC liver tissue (23 cases). As a control, 16 livers of chronic viral hepatitis (CVH) were used. Reverse transcription-polymerase chain reaction and semiquantitative analysis revealed that the relative ratio of CXCR3/CCR4 mRNAs was higher in early PBC (0.76+/-0.56) rather than in advanced PBC (0.25+/-0.11), and was comparable to that in active CVH (0.67+/-0.43). By immunohistochemistry, the ratio of CXCR3-/CCR4-positive mononuclear cells in portal tracts of early PBC (4.77+/-1.70) is significantly higher than that of advanced PBC (3.11+/-1.26), and also than that of mild and of active CVH. In early PBC, mononuclear cells positive for CXCR3 were dense around the damaged bile ducts. These data suggest that the enhanced shift toward type1 occurs in portal tracts of early PBC and that the imbalance of type1/type2 changes during the course of PBC. This study provides further support for the state of enhanced type1 response in early PBC and potentially offers a possibility to suppress the bile duct lesions and to prevent the progression of PBC from early to advanced stages by reversing the type1/type2 imbalance.