Reduced TRPC Channel Expression in Psoriatic Keratinocytes Is Associated with Impaired Differentiation and Enhanced Proliferation

Psoriasis is a characteristic inflammatory and scaly skin condition with typical histopathological features including increased proliferation and hampered differentiation of keratinocytes. The activation of innate and adaptive inflammatory cellular immune responses is considered to be the main trigger factor of the epidermal changes in psoriatic skin. However, the molecular players that are involved in enhanced proliferation and impaired differentiation of psoriatic keratinocytes are only partly understood. One important factor that regulates differentiation on the cellular level is Ca2+. In normal epidermis, a Ca2+ gradient exists that is disturbed in psoriatic plaques, favoring impaired keratinocyte proliferation. Several TRPC channels such as TRPC1, TRPC4, or TRPC6 are key proteins in the regulation of high [Ca2+]ex induced differentiation. Here, we investigated if TRPC channel function is impaired in psoriasis using calcium imaging, RT-PCR, western blot analysis and immunohistochemical staining of skin biopsies. We demonstrated substantial defects in Ca2+ influx in psoriatic keratinocytes in response to high extracellular Ca2+ levels, associated with a downregulation of all TRPC channels investigated, including TRPC6 channels. As TRPC6 channel activation can partially overcome this Ca2+ entry defect, specific TRPC channel activators may be potential new drug candidates for the topical treatment of psoriasis

Changes in the sex hormone profile of male patients with moderate-to-severe plaque-type psoriasis under systemic therapy: results of a prospective longitudinal pilot study

Patients with moderate-to-severe plaque-type psoriasis exhibit increased cardiovascular mortality. Recent publications point towards psoriasis-induced insulin resistance as an important pathomechanism driving cardiovascular comorbidity in these patients. As the hormonal status in general and sex hormone-binding globulin (SHBG) in particular serve as sensitive indicators for insulin resistance, we analysed these parameters in the context of a set of multiple additional clinical and laboratory measurements in a cohort of male patients. Of 33 consecutively enrolled male patients receiving continuous systemic therapy for their moderate-to-severe plaque-type psoriasis, 23 male patients for whom all parameters could be collected over a 24-week treatment period were included in this analysis. At baseline, testosterone levels varied between 212 and 660 ng/ml (median: 377.0), and SHBG between 11.9 and 46.0 nmol/l (median: 29.2), thus documenting lack of hypogonadism among these patients. Clinically, 19/23 patients experienced at least a 50% reduction in their PASI under therapy. Using a multivariate regression model to further analyse the sub-group of patients responding to treatment, hs-CRP, PASI, leptin and resistin all improved under effective systemic anti-inflammatory therapy, thus losing their significant influence on SHBG. SHBG performed well as a sensitive biomarker for insulin resistance and systemic inflammation in these patients. Its improvement, as well as the reduction of resistin serum levels, most likely reflects a state of reduced cardiovascular risk in patients undergoing effective continuous systemic therapy. Long-term safety data, generated e.g. from psoriasis registries, are needed to assess whether this effect translates into reduced cardiovascular mortality

CELLULAR RESPONSES TO EGG-OIL (CHARISMON©)

Egg-oil (Charismon©) is known for its beneficial action in wound healing and other skin irritancies and its antibacterial activity. The physiological basis for these actions has been investigated using cells in culture: HaCaT-cells (immortalized human keratinocytes), human endothelial cells in culture (HUVEC), peripheral blood mononuclear lymphocytes (PBML) and a full thickness human skin model (FTSM). Emphasis was on the influence of egg-oil on cell migration and IL-8 production in HaCaT cells, respiration, mitochondrial membrane potential, reactive oxygen (ROS) production and proliferation in HUVEC and HaCaT cells, cytokine and interleukin production in PBML and UV-light induced damage of FTSM. IL-8 production by HaCaT cells is stimulated by egg-oil whilst in phythemagglutinin-activated PBMLs production of the interleukins IL-2, IL-6, IL-10 and IFN-γ and TFN-α is reduced. ROS-production after H2O2 stimulation first is enhanced but later on reduced. Respiration becomes activated due to partial uncoupling of the mitochondrial respiratory chain and proliferation of HaCaT and HUVEC is reduced. Recovery of human epidermis cells in FTSM after UV-irradiation is strongly supported by egg-oil. These results support the view that egg-oil acts through reduction of inflammatory processes and ROS production. Both these processes are equally important in cellular aging as in healing of chronic wounds

Psoriasis patients show signs of insulin resistance

BACKGROUND: Recent observations suggest that psoriasis is a risk factor for the development of coronary artery calcification which in turn represents an indicator for atherosclerosis. OBJECTIVE: To clarify a possible pathogenetic link between psoriasis and atherosclerosis, we studied the metabolic state of patients with psoriasis. METHODS: Thirty-nine consecutive patients with moderate-to-severe plaque-type psoriasis were enrolled in the study. Detailed information was obtained on the patients' clinical picture and history of psoriasis, smoking habits and medication. The body mass index (BMI) of the patients was calculated. Laboratory investigations focused on values for inflammation, lipid profile and multiple cytokines. The intima-media thickness of the carotid artery was measured by ultrasound, and an oral glucose tolerance test was performed to calculate the homeostasis model assessment of insulin resistance (HOMA). RESULTS: Numerous well-recognized correlations such as between BMI and HOMA (P < 0.02) as well as BMI and vessel wall thickness (P < 0.05) were successfully reproduced, thus confirming consistency of our dataset. With regard to psoriasis, we observed a significant correlation between the Psoriasis Area and Severity Index (PASI) score and insulin secretion. Moreover, the PASI score was significantly correlated with serum resistin levels--a cytokine known to be increased in insulin resistance. CONCLUSIONS: Taken together, several measurements indicative of insulin resistance were found to be significantly correlated with the PASI score. The concept of insulin resistance as a consequence of chronic inflammation and possible pathogenetic cause for comorbidities known to be associated with psoriasis is supported by these data. Our findings validate further studies on larger cohorts as well as interventional studies

Effective continuous systemic therapy of severe plaque-type psoriasis is accompanied by amelioration of biomarkers of cardiovascular risk: results of a prospective longitudinal observational study

BACKGROUND: Severe psoriasis is associated with significant cardiovascular mortality. OBJECTIVES: We investigated the effects of continuous systemic therapy on the cardiovascular risk of patients with severe plaque-type psoriasis. METHODS: A total of 42 consecutive patients receiving systemic treatment for their severe plaque-type psoriasis were included. The clinical course was monitored over 24 weeks. Initially as well as after 12 and 24 weeks, oral glucose tolerance tests were performed along with comprehensive laboratory monitoring. RESULTS: Responding patients, defined as a Psoriasis Area and Severity Index (PASI)-50 response, showed correlations between the PASI and high-sensitive C-reactive protein (r = 0.45, P = 0.03) as well as with vascular endothelial growth factor (r = 0.76, P = 0.007). The adipokine resistin was positively and the potentially cardio-protective adiponectin was negatively correlated with the PASI (r = 0.50, P = 0.02 and r = -0.56, P = 0.007, respectively). Oral glucose tolerance tests yielded a correlation between the PASI and plasma levels for C-peptide (r = 0.73, P = 0.02) at t = 120 min in patients with a pathological Homeostasis Model Assessment (>2.5), indicating that the state of peripheral insulin resistance is driven at least in part by the severity of the psoriatic inflammation. Correlations between the change of adipokine levels and change in PASI were more pronounced among patients with better clinical improvement (PASI-75 vs. PASI-50). CONCLUSIONS: We document an amelioration of biomarkers of cardiovascular risk in patients with severe plaque-type psoriasis responding to continuous systemic therapy. The impact on the patients'metabolic state was found to be better if the psoriatic inflammation was controlled for longer. Future studies need to compare the cardioprotective effects of different treatment modalities, based on hard clinical endpoints

Systemic therapy of plaque-type psoriasis ameliorates endothelial cell function: results of a prospective longitudinal pilot trial

Severe psoriasis is associated with significant cardiovascular mortality. We therefore investigated the effects of systemic therapy on the cardiovascular risk of psoriasis patients. Thirteen consecutive patients receiving fumaric acid esters were included and followed for 24 weeks both clinically and by means of laboratory monitoring, 10 completed the study. Eight of ten patients showed a PASI-50 response. Two of three patients with clinical insulin resistance (Homeostasis Model Assessment of insulin resistance >2.5) showed normal insulin responsiveness at the end of the study. Clinical improvement was paralleled by a reduction of high-sensitive CRP serum levels (median -25%). There was a trend toward reduced serum levels for the vascular endothelial growth factor (median -10%) and resistin (median -4%), while the potentially cardio-protective adiponectin showed a trend toward increased serum levels under therapy (median +19%). Systemic endothelial function assessed by venous occlusion plethysmography revealed an improvement of endothelial vasodilator function after 24 weeks of treatment (p < 0.02). This is the first prospective study documenting an amelioration of endothelial cell function in patients with moderate-to-severe plaque-type psoriasis under effective continuous systemic therapy. Future studies need to compare the cardioprotective effects of different treatment modalities, based on hard end points such as the rate of myocardial infarction

Specific TRPC6 Channel Activation, a Novel Approach to Stimulate Keratinocyte Differentiation*S⃞

The protective epithelial barrier in our skin undergoes constant regulation, whereby the balance between differentiation and proliferation of keratinocytes plays a major role. Impaired keratinocyte differentiation and proliferation are key elements in the pathophysiology of several important dermatological diseases, including atopic dermatitis and psoriasis. Ca2+ influx plays an essential role in this process presumably mediated by different transient receptor potential (TRP) channels. However, investigating their individual role was hampered by the lack of specific stimulators or inhibitors. Because we have recently identified hyperforin as a specific TRPC6 activator, we investigated the contribution of TRPC6 to keratinocyte differentiation and proliferation. Like the endogenous differentiation stimulus high extracellular Ca2+ concentration ([Ca2+]o), hyperforin triggers differentiation in HaCaT cells and in primary cultures of human keratinocytes by inducing Ca2+ influx via TRPC6 channels and additional inhibition of proliferation. Knocking down TRPC6 channels prevents the induction of Ca2+- and hyperforin-induced differentiation. Importantly, TRPC6 activation is sufficient to induce keratinocyte differentiation similar to the physiological stimulus [Ca2+]o. Therefore, TRPC6 activation by hyperforin may represent a new innovative therapeutic strategy in skin disorders characterized by altered keratinocyte differentiation

Transcriptional induction of junctional adhesion molecule-C gene expression in activated T cells

Junctional adhesion molecule (JAM)-C is an Ig superfamily protein, which is involved in the regulation of various inflammatory and vascular events such as transendothelial leukocyte migration. JAM-C is expressed highly on the surface of endothelial cells and platelets, whereas expression in T lymphocytes is not well studied. To investigate the specific gene regulation of JAM-C in T lymphocytes, we determined JAM-C expression in quiescent and activated human T cells. Treatment with the polyclonal T cell activator PHA increased surface and total JAM-C expression in T cells time- and dose-dependently, as determined by flow cytometry and immunoblot analysis. In contrast, no up-regulation of JAM-A in activated T cells was detectable. The highest level of JAM-C up-regulation by PHA was observed in CD3+forkhead box P3+ and CD4+CD25high T cells. Moreover, TCR activation with combined anti-CD3 and anti-CD28 stimulation induced JAM-C expression in T cells. JAM-C induction occurred at the mRNA level, suggesting a transcriptional regulatory mechanism of JAM-C expression. Accordingly, we studied the regulation of the human JAM-C gene promoter in transiently transfected T cells. Luciferase activity of a JAM-C promoter gene construct with three potential consensus sites for the transcription factor NFAT was induced markedly in activated T cells. Finally, pretreatment with two pharmacological inhibitors of calcineurin, cyclosporin A, and FK-506, but not with MAPK inhibitors, blocked JAM-C induction in activated T cells. In summary, JAM-C is up-regulated in activated human T lymphocytes via a transcriptional mechanism, suggesting a potential role of JAM-C in T cell functions