Role of IL‐10 and TGF‐β in melanoma

IL‐10 and TGF‐β are immunosuppressive cytokines expressed in tumors including melanoma and, therefore, deemed major cause for failing antitumor immune responses. Re‐evaluating their role, we compared their expression by quantitative RT‐PCR in melanoma and skin of healthy individuals, tested their induction in dendritic cells and T cells co‐cultured with tumor cells, and their effects on the immune cells. Both cytokines as well as their receptors were expressed in melanoma at significantly lower levels than in healthy skin. Consequently, the expressions of IL‐10‐responsive SOCS‐3 and TGF‐β‐responsive Smad‐7 were low in tumors but high in healthy skin. T cells co‐cultured with tumor cells developed an anergic state without increased IL‐10 or TGF‐β expression. In vitro tumor‐induced immature dendritic cells produced high IL‐10 levels and less efficiently induced T‐cell proliferation. Nonetheless, they could be induced to mature, and blocking IL‐10 did not alter the capacity of the resulting mature dendritic cells to stimulate T cells. Mature dendritic cells co‐cultured with tumor cells produced increased IL‐10 but decreased TGF‐β and more efficiently induced T‐cell proliferation. The lack of correlation of IL‐10 and TGF‐β with immune deficits in situ and in vitro suggests re‐evaluating their roles in cancer.     

REGγ accelerates melanoma formation by regulating Wnt/β‐catenin signalling pathway

It has been reported that the proteasome activator REGγ is associated with multiple oncogenic pathways in human cancers. However, the role of REGγ in the development of melanoma and the underlying mechanisms remain unclear. In this study, we attempted to investigate the effects of REGγ on human melanoma cell proliferation in vitro and in vivo. We demonstrated that knockdown of REGγ inhibited melanoma cell growth and arrested melanoma cell at G1 phase. Furthermore, depletion of REGγ also inhibited the xenograft growth of human melanoma. Mechanistically, REGγ activates Wnt/β‐catenin signal pathway by degrading GSK‐3β in melanoma cell lines and mouse models. Transient knockdown of β‐catenin effectively blocked cell proliferation in REGγ wild‐type melanoma cells. In human melanoma samples, REGγ was overexpressed and positively correlated with β‐catenin levels. This study demonstrates that REGγ is a central molecule in the development of melanoma by regulating Wnt/β‐catenin pathway. This suggests that targeting REGγ could be an alternative therapeutic approach for melanoma.     

Transforming growth factor‐β enhances matrix metalloproteinase‐2 expression and activity through AKT in fibroblasts derived from angiofibromas in patients with tuberous sclerosis complex

Background Patients with tuberous sclerosis complex (TSC) develop fibrous tumours in the brain, skin, kidney, heart and lungs due to TSC1/2 mutations. In the skin, patients develop angiofibromas that have vascular and fibrotic components in which transforming growth factor (TGF)‐β and matrix metalloproteinase (MMP)‐2 are important. Objectives To investigate if the TGF‐β axis and MMP‐2 play an important role in the pathogenesis of TSC angiofibromas. Methods Samples from TSC angiofibromas and normal skin were measured for expression of TGF‐β and MMP‐2 by immunohistochemistry and real‐time polymerase chain reaction. Fibroblasts grown from TSC angiofibromas (TSC fibroblasts) were incubated with TGF‐β. Expression of ERK, AKT and S6K was measured by Western blotting, and MMP‐2 expression and activity were determined by enzyme‐linked immunosorbent assay and gelatin zymography, respectively. Results There was an increase in the expression of TGF‐β and MMP‐2 in TSC tumours compared with those in normal skin. The baseline expression of MMP‐2 was increased in conditioned medium from TSC fibroblasts. In addition, TGF‐β enhanced MMP‐2 production and activity, which could be abrogated by pretreatment with an AKT inhibitor (LY294002) but not with rapamycin. Finally, there was a significant colocalization of TGF‐β and MMP‐2 in the TSC tumours. Conclusions There is an increase of MMP‐2 as a result of TGF‐β acting through AKT in TSC tumour cells. This regulation of the TGF‐β–AKT–MMP‐2 axis is independent of mammalian target of rapamycin (mTOR) signalling. In addition to targeting the mTOR pathway, targeting TGF‐β simultaneously could block dysregulated tissue remodelling in TSC tumours.     

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF‐β/Smad pathway

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars. To investigate the therapeutic effects of loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that loureirin B dose‐dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α ‐ smooth muscle actin (α ‐ SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α ‐ SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, loureirin B effectively inhibited TGF‐β1‐induced upregulation of ColI, ColIII and α‐SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF‐β1‐stimulated fibroblasts. Taken together, this study demonstrates that loureirin B could downregulate the expression of fibrosis‐related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF‐β1‐induced fibrosis, during which TGF‐β1/Smad2/3 pathway is likely involved. These findings suggest that loureirin B is a potential therapeutic compound for HS treatment.     

CD109, a novel TGF‐β antagonist,decreases fibrotic responses in a hypoxic wound model

Excessive extracellular matrix deposition that occurs in many fibrotic skin disorders such as hypertrophic scarring and scleroderma is often associated with hypoxia. CD109 is a novel TGF‐β co‐receptor and TGF‐β antagonist shown to inhibit TGF‐β‐induced extracellular matrix protein production in vitro. We examined whether CD109 is able to regulate extracellular matrix deposition under low oxygen tension in vivo using transgenic mice overexpressing CD109 in the epidermis. By creating dorsal bipedicle skin flaps with centrally located excisional wounds in these mice and their wild‐type littermates, we generated a novel murine hypoxic wound model. Mice were sacrificed on 7 or 14 days post‐wounding, and tissues were harvested for histological and biochemical analysis. Hypoxic wounds in both transgenic and wild‐type mice showed increased levels of HIF‐1α and delayed wound closure, validating this model in mice. Hypoxic wounds in CD109 transgenic mice demonstrated decreased collagen type 1 and fibronectin expression, and reduced dermal thickness on day 7 post‐wounding as compared to those in wild‐type mice and to non‐hypoxic control wounds. These results suggest that CD109 decreases extracellular matrix production and fibrotic responses during hypoxic wound healing. Manipulating CD109 levels may have potential therapeutic value for the treatment of fibrotic skin disorders associated with poor oxygen delivery.     

Treatment of refractory bullous pemphigoid with IFN‐α‐2b: A case report

We reported a patient with refractory bullous pemphigoid (BP), who had a higher level of eosinophils and serum IgE. The case showed less response to various therapies. Edematous erythema and new blisters appeared constantly. Considering IFN‐α‐2b treatment could significantly decrease blood eosinophils, we therefore expected that IFN‐α‐2b could be effective in the treatment of BP. After treated with IFN‐α‐2b, the patient's good response to the treatment suggested our hypothesis.     

Histamine suppresses regulatory T cells mediated by TGF‐β in murine chronic allergic contact dermatitis

Regulatory T cells (Tregs) suppress effector T cells and ameliorate contact hypersensitivity (CH); however, the role of Tregs in chronic allergic contact dermatitis (CACD) has not been assessed. Repeated elicitation of CH has been used to produce CACD models in mice. We previously showed that the presence of histamine facilitates the creation of eczematous lesions in this model using histidine decarboxylase (HDC) (?/?) mice. Therefore, the effects of histamine on Tregs in the CACD model were investigated in this study. CACD was developed by repeated epicutaneous application of 2, 4, 6‐trinitro‐1‐chlorobenzene (TNCB) on HDC (+/+) and HDC (?/?) murine skin to assess the effects of histamine in CACD. Histamine aggravated CACD in the murine model and suppressed the number of Tregs in the skin. Histamine also suppressed the level of TGF‐β1 in this model. Recombinant TGF‐β1 or anti‐TGF‐β1 antibody was injected into the dorsal dermis of HDC (+/+) mice daily just before TNCB challenge to determine the effects of histamine‐regulated TGF‐β on the Treg population in CACD. Recombinant TGF‐β1 injection promoted the infiltration of Tregs in the skin and the production of IL‐10; however, anti‐TGF‐β1 antibody injection suppressed the number of Tregs in the skin and the production of IL‐10. Histamine suppresses the number of Tregs in CACD, and this effect is mediated by TGF‐β.     

Integrin αE(CD103) is induced but plays no pathogenic role in psoriasiform skin lesions of TGFβ1 transgenic mice

T‐cells expressing α_E(CD103), an integrin induced by TGFβ on T‐cells in vitro, accumulate within epithelia in inflammatory disorders, including psoriasis. However, it is unclear, if and how α_E(CD103) contributes to skin inflammation. Using two complementary approaches, we have investigated α_E(CD103) in psoriasis‐like skin inflammation of mice with transgenic epidermal expression of human TGFβ1: α_E(CD103) was inhibited by function‐blocking antibodies in vivo, and double‐mutants with additional α_E(CD103)‐depletion were generated in two different genetic backgrounds. Epidermal hTGFβ1 expression was associated with prominent expression of α_E(CD103) on infiltrating cells. However, neither treatment with α_E(CD103)‐blocking antibodies nor deficiency of α_E(CD103) in double‐mutant mice altered the psoriasis‐like phenotype. In addition, histopathological and flow cytometric analyses revealed similar pathological skin alterations and lymphocyte subgroups in the different mouse strains. Thus, while α_E(CD103) expression is indeed associated with hTGFβ1 in vivo, it has little, if any, influence on the course of the psoriasis‐like phenotype in K5.hTGFβ1 transgenic mice.