Martina Gatzka

Reduced CD18 Levels Drive Regulatory T Cell Conversion into Th17 Cells in the CD18hypo PL/J Mouse Model of Psoriasis

Defective development and function of CD4+CD25high+Foxp3+ regulatory T cells (Tregs) contribute to the pathogenesis of psoriasis and other autoimmune diseases. Little is known about the influence of adhesions molecules on the differentiation of Foxp3+ Tregs into proinflammatory Th17 cells occurring in lesional skin and blood of psoriasis patients. In the CD18hypo PL/J mouse model of psoriasis, reduced expression of CD18/β2 integrin to 2–16% of wild-type levels is associated with progressive loss of Tregs, impaired cell–cell contact between Tregs and dendritic cells (DCs), as well as Treg dysfunction as reported earlier. In the present investigation, Tregs derived from CD18hypo PL/J mice were analyzed for their propensity to differentiate into IL-17–producing Th17 cells in vivo and in in vitro Treg–DC cocultures. Adoptively transferred CD18hypo PL/J Tregs were more inclined toward conversion into IL-17–producing Th17 cells in vivo in an inflammatory as well as noninflammatory environment compared with CD18wt PL/J Tregs. Addition of neutralizing Ab against CD18 to Treg–DC cocultures in vitro promoted conversion of CD18wt PL/J Tregs to Th17 cells in a dose-dependent manner similar to conversion rates of CD18hypo PL/J Tregs. Reduced thymic output of naturally occurring Tregs and peripheral conversion of Tregs into Th17 cells therefore both contribute to the loss of Tregs and the psoriasiform dermatitis observed in CD18hypo PL/J mice. Our data overall indicate that CD18 expression levels impact Treg development as well as Treg plasticity and that differentiation of Tregs into IL-17–producing Th17 cells is distinctly facilitated by a subtotal deficiency of CD18.

Reduction of CD18 promotes expansion of inflammatory γδ T cells collaborating with CD4+ T cells in chronic murine psoriasiform dermatitis.

IL-17 is a critical factor in the pathogenesis of psoriasis and other inflammatory diseases. The impact of γδ T cells, accounting for an important source of IL-17 in acute murine IL-23– and imiquimod-induced skin inflammation, in human psoriasis is still unclear. Using the polygenic CD18hypo PL/J psoriasis mouse model spontaneously developing chronic psoriasiform dermatitis due to reduced CD18/β2 integrin expression to 2–16% of wild-type levels, we investigated in this study the influence of adhesion molecule expression on generation of inflammatory γδ T cells and analyzed the occurrence of IL-17–producing γδ and CD4+ T cells at different disease stages. Severity of CD18hypo PL/J psoriasiform dermatitis correlated with a loss of skin-resident Vγ5+ T cells and concurrent skin infiltration with IL-17+, IL-22+, and TNF-α+ γδTCRlow cells preceded by increases in Vγ4+ T cells in local lymph nodes. In vitro, reduced CD18 levels promoted expansion of inflammatory memory-type γδ T cells in response to IL-7. Similar to IL-17 or IL-23/p19 depletion, injection of diseased CD18hypo PL/J mice with anti-γδTCR Abs significantly reduced skin inflammation and largely eliminated pathological γδ and CD4+ T cells. Moreover, CD18hypo γδ T cells induced allogeneic CD4+ T cell responses more potently than CD18wt counterparts and, upon adoptive transfer, triggered psoriasiform dermatitis in susceptible hosts. These results demonstrate a novel function of reduced CD18 levels in generation of pathological γδ T cells that was confirmed by detection of increases in CD18low γδ T cells in psoriasis patients and may also have implications for other inflammatory diseases.

A Dermatologist's Ammunition in the War Against Smoking: A Photoaging App

This viewpoint reviews the perspectives for dermatology as a specialty to go beyond the substantial impact of smoking on skin disease and leverage the impact of skin changes on a persons self-concept and behavior in the design of effective interventions for smoking prevention and cessation.

T-cell plasticity in inflammatory skin diseases--the good, the bad, and the chameleons.

According to the concept of T‐cell plasticity, peripheral T cells – once differentiated into a specific T cell subset – may, in response to new environmental cues or signaling alterations, adopt the phenotype of a different helper cell subset with regard to cytokine production and regulatory functions. In a variety of T cell‐mediated inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, and psoriasis, T‐cell plasticity – in particular the conversion of regulatory T cells (Tregs) to IL‐17‐producing inflammatory cells – has recently been described as key pathomechanism contributing to the aggravation of inflammatory symptoms and disease chronification. Apart from psoriasis, the phenomenon of immune cell plasticity may also have a role in other inflammatory conditions of the skin showing a T cell component and/or an IL‐17‐mediated pathology, such as lichen planus, lupus erythematosus, blistering diseases, allergic disorders, and others. This review summarizes the basic molecular mechanisms regulating T‐cell fate decisions and plasticity in inflamed skin and in other lymphoid organs. Moreover, it explores the effect of established targeted therapies as well as alternative concepts with a focus on how to prevent the unwanted conversion of “helpful” T cells and other beneficial immune cells to pathological inflammatory vermin.

Senescent fibroblast-derived Chemerin promotes squamous cell carcinoma migration

Aging is associated with a rising incidence of cutaneous squamous cell carcinoma (cSCC), an aggressive skin cancer with the potential for local invasion and metastasis. Acquisition of a senescence-associated secretory phenotype (SASP) in dermal fibroblasts has been postulated to promote skin cancer progression in elderly individuals. The underlying molecular mechanisms are largely unexplored. We show that Chemerin, a previously unreported SASP factor released from senescent human dermal fibroblasts, promotes cSCC cell migration, a key feature driving tumor progression. Whereas the Chemerin abundance is downregulated in malignant cSCC cells, increased Chemerin transcripts and protein concentrations are detected in replicative senescent fibroblasts in vitro and in the fibroblast of skin sections from old donors, indicating that a Chemerin gradient is built up in the dermis of elderly. Using Transwell® migration assays, we show that Chemerin enhances the chemotaxis of different cSCC cell lines. Notably, the Chemerin receptor CCRL2 is remarkably upregulated in cSCC cell lines and human patient biopsies. Silencing Chemerin in senescent fibroblasts or the CCRL2 and GPR1 receptors in the SCL-1 cSCC cell line abrogates the Chemerin-mediated chemotaxis. Chemerin triggers the MAPK cascade via JNK and ERK1 activation, whereby the inhibition impairs the SASP- or Chemerin-mediated cSCC cell migration. Taken together, we uncover a key role for Chemerin, as a major factor in the secretome of senescent fibroblasts, promoting cSCC cell migration and possibly progression, relaying its signals through CCRL2 and GPR1 receptors with subsequent MAPK activation. These findings might have implications for targeted therapeutic interventions in elderly patients.

Loss of p53 compensates osteopenia in murine Mysm1 deficiency

Histone modifications critically contribute to the epigenetic orchestration of bone homeostasis—in part, by modifying the access of transcription factors to specific genes involved in the osteogenic differentiation process of bone marrow mesenchymal stem cells (MSCs) and osteoblasts. Based on our previous finding that histone H2A deubiquitinase 2A‐DUB/Mysm1 interacts with the p53 axis in hematopoiesis and tissue development, we analyzed the molecular basis of the skeletal phenotype of Mysm1‐deficient mice and dissected the underlying p53‐dependent and ‐independent mechanisms. Visible morphologic, skeletal deformations of young Mysm1‐deficient mice— including a kinked and truncated tail and shortened long bones—were associated with osteopenia of long bones. On the cellular level, Mysm1‐deficient primary osteoblasts displayed reduced potential to differentiate into mature osteoblasts, as indicated by decreased expression of osteogenic markers. Reduced osteogenic differentiation capacity of Mysm1‐deficient osteoblasts was accompanied by an impaired induction of osteogenic transcription factor Runx2. Osteogenic differentiation of Mysm1−/− MSCs, however, was not compromised in vitro. In line with defective hematopoietic development of Mysm1‐deficient mice, Mysm1−/− osteoclasts had reduced resorption activity and were more prone to apoptosis in TUNEL assays. Skeletal alterations and osteopenia of Mysm1‐deficient mice were phenotypically completely rescued by simultaneous ablation of p53 in p53−/−Mysm1−/− double‐deficient mice— although p53 deficiency did not restore Runx2 expression in Mysm1−/− osteoblasts on the molecular level but, instead, enhanced proliferation and osteogenic differentiation of MSCs. In summary, our results demonstrate novel roles for Mysm1 in osteoblast differentiation and osteoclast formation, resulting in osteopenia in Mysm1‐deficient mice that could be abrogated by the loss of p53 from increased osteogenic differentiation of Mysm1−/−p53−/− MSCs.— Haffner‐Luntzer, M., Kovtun, A., Fischer, V., Prystaz, K., Hainzl, A., Kroeger, C. M., Krikki, I., Brinker, T. J., Ignatius, A., Gatzka, M. Loss of p53 compensates osteopenia in murine Mysml deficiency. FASEB J. 32, 1957–1968 (2018). www.fasebj.org

MYSM1/2A-DUB is an epigenetic regulator in human melanoma and contributes to tumor cell growth

Histone modifying enzymes, such as histone deacetylases (HDACs) and polycomb repressive complex (PRC) components, have been implicated in regulating tumor growth, epithelial-mesenchymal transition, tumor stem cell maintenance, or repression of tumor suppressor genes - and may be promising targets for combination therapies of melanoma and other cancers. According to recent findings, the histone H2A deubiquitinase 2A-DUB/Mysm1 interacts with the p53-axis in hematopoiesis and tissue differentiation in mice, in part by modulating DNA-damage responses in stem cell and progenitor compartments. Based on the identification of alterations in skin pigmentation and melanocyte specification in Mysm1-deficient mice, we hypothesized that MYSM1 may be involved in melanoma formation. In human melanoma samples, expression of MYSM1 was increased compared with normal skin melanocytes and nevi and co-localized with melanocyte markers such as Melan-A and c-KIT. Similarly, in melanoma cell lines A375 and SK-MEL28 and in murine skin, expression of the deubiquitinase was detectable at the mRNA and protein level that was inducible by growth factor signals and UVB exposure, respectively. Upon stable silencing of MYSM1 in A375 and SK-MEL-28 melanoma cells by lentivirally-mediated shRNA expression, survival and proliferation were significantly reduced in five MYSM1 shRNA cell lines analyzed compared with control cells. In addition, MYSM1-silenced melanoma cells proliferated less well in softagar assays. In context with our finding that MYSM1 bound to the c-MET promoter region in close vicinity to PAX3 in melanoma cells, our data indicate that MYSM1 is an epigenetic regulator of melanoma growth and potentially promising new target for tumor therapy.Histone modifying enzymes, such as histone deacetylases (HDACs) and polycomb repressive complex (PRC) components, have been implicated in regulating tumor growth, epithelial-mesenchymal transition, tumor stem cell maintenance, or repression of tumor suppressor genes - and may be promising targets for combination therapies of melanoma and other cancers. According to recent findings, the histone H2A deubiquitinase 2A-DUB/Mysm1 interacts with the p53-axis in hematopoiesis and tissue differentiation in mice, in part by modulating DNA-damage responses in stem cell and progenitor compartments. Based on the identification of alterations in skin pigmentation and melanocyte specification in Mysm1-deficient mice, we hypothesized that MYSM1 may be involved in melanoma formation. In human melanoma samples, expression of MYSM1 was increased compared with normal skin melanocytes and nevi and co-localized with melanocyte markers such as Melan-A and c-KIT. Similarly, in melanoma cell lines A375 and SK-MEL-28 and in murine skin, expression of the deubiquitinase was detectable at the mRNA and protein level that was inducible by growth factor signals and UVB exposure, respectively. Upon stable silencing of MYSM1 in A375 and SK-MEL-28 melanoma cells by lentivirally-mediated shRNA expression, survival and proliferation were significantly reduced in five MYSM1 shRNA cell lines analyzed compared with control cells. In addition, MYSM1-silenced melanoma cells proliferated less well in softagar assays. In context with our finding that MYSM1 bound to the c-MET promoter region in close vicinity to PAX3 in melanoma cells, our data indicate that MYSM1 is an epigenetic regulator of melanoma growth and potentially promising new target for tumor therapy.

A skin cancer prevention photoageing intervention for secondary schools in Brazil delivered by medical students: protocol for a randomised controlled trial.

Introduction The incidence of melanoma is increasing faster than any other major cancer both in Brazil and worldwide. The Southeast of Brazil has especially high incidences of melanoma, and early detection is low. Exposure to UV radiation represents a primary risk factor for developing melanoma. Increasing attractiveness is a major motivation for adolescents for tanning. A medical student-delivered intervention that harnesses the broad availability of mobile phones as well as adolescents’ interest in their appearance may represent a novel method to improve skin cancer prevention. Methods and analysis We developed a free mobile app (Sunface), which will be implemented in at least 30 secondary school classes, each with 21 students (at least 30 classes with 21 students for control) in February 2018 in Southeast Brazil via a novel method called mirroring. In a 45 min classroom seminar, the students’ altered three-dimensional selfies on tablets are ‘mirrored’ via a projector in front of their entire class, showing the effects of unprotected UV exposure on their future faces. External block randomisation via computer is performed on the class level with a 1:1 allocation. Sociodemographic data, as well as skin type, ancestry, UV protection behaviour and its predictors are measured via a paper–pencil questionnaire before as well as at 3 and 6 months postintervention. The primary end point is the group difference in the 30-day prevalence of daily sunscreen use at a 6-month follow-up. Secondary end points include (1) the difference in daily sunscreen use at a 3-month follow-up, (2) if a self-skin examination in accordance with the ABCDE rule was performed within the 6-month follow-up and (3) the number of tanning sessions. Ethics and dissemination Ethical approval was obtained from the ethics committee of the University of Itauna. Results will be disseminated at conferences and in peer-reviewed journals. Trial registration number NCT03178240; Pre-results.

Skin under Tnf influence: how regulatory T cells work against macrophages in psoriasis

Tumour necrosis factor (TNF)‐α and interleukin (IL)‐17 are key cytokines driving psoriasis and other inflammatory autoimmune diseases, and thus represent effective targets for anti‐psoriatic therapy. In a recent issue of The Journal of Pathology, Leite Dantas et al explore a mouse model of TNF‐mediated psoriasiform dermatitis and arthritis with doxycyclin‐inducible general overexpression of human TNF (ihTNFtg) mice for the contributions of macrophages and T cells in skin inflammation – with some unexpected and interesting findings. Although T cells are commonly known as major proinflammatory players in psoriasis, in the ihTNFtg mouse model macrophages were the predominant cells causing inflammation, and T cells, represented by Foxp3+ regulatory T cells, mainly formed the opposition to keep inflammation in check. In addition to offering a new perspective on potential alternative initiation mechanisms in psoriatic skin inflammation, this constellation illustrates how cellular networks in inflammatory conditions evolve according to the prevailing cytokine, and may help to explain individual responses to either anti‐TNF‐α or anti‐IL‐17 therapy regimens in psoriasis. Copyright

Skin under Tnf influence: How Tregs work against macrophages in psoriasis.

Tumour necrosis factor (TNF)‐α and interleukin (IL)‐17 are key cytokines driving psoriasis and other inflammatory autoimmune diseases, and thus represent effective targets for anti‐psoriatic therapy. In a recent issue of The Journal of Pathology, Leite Dantas et al explore a mouse model of TNF‐mediated psoriasiform dermatitis and arthritis with doxycyclin‐inducible general overexpression of human TNF (ihTNFtg) mice for the contributions of macrophages and T cells in skin inflammation – with some unexpected and interesting findings. Although T cells are commonly known as major proinflammatory players in psoriasis, in the ihTNFtg mouse model macrophages were the predominant cells causing inflammation, and T cells, represented by Foxp3+ regulatory T cells, mainly formed the opposition to keep inflammation in check. In addition to offering a new perspective on potential alternative initiation mechanisms in psoriatic skin inflammation, this constellation illustrates how cellular networks in inflammatory conditions evolve according to the prevailing cytokine, and may help to explain individual responses to either anti‐TNF‐α or anti‐IL‐17 therapy regimens in psoriasis. Copyright