J. Hunyadi

Investigation of micronized titanium dioxide penetration in human skin xenografts and its effect on cellular functions of human skin-derived cells

Abstract:  Titanium dioxide (TiO2) nanoparticles are ubiquitously used materials in everyday life (e.g. paints, household products and plastic goods). However, despite the wide array of common applications, their pathogenetic role was also suggested under certain conditions (e.g. pulmonary neoplasias and lung fibrosis). From a dermatological point of view, it is also of great importance that TiO2 also serves as a physical photoprotective agent in sunscreens and is widely used in various cosmetic products. However, the effect of TiO2 on human cutaneous functions is still unknown. Therefore, in the current study, we investigated the in vivo penetration of TiO2 via human skin transplanted to immunodeficient mice and, furthermore, we measured the in vitro effects of nanoparticles on various functional properties of numerous epidermal and dermal cells in culture. Hereby, using various nuclear microscopy methods, we provide the first evidence that TiO2 nanoparticles in vivo do not penetrate through the intact epidermal barrier. However, we also report that TiO2, when exposed directly to cell cultures in vitro, exerts significant and cell‐type dependent effects on such cellular functions as viability, proliferation, apoptosis and differentiation. Therefore, our novel findings will hopefully inspire one to systemically explore in future, clinically oriented trials whether there is indeed a risk from micronized TiO2‐containing products on skin with an impaired stratum corneum barrier function.

Detection of Poly(ADP-ribose) Polymerase Activation in Oxidatively Stressed Cells and Tissues Using Biotinylated NAD Substrate

Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme activated by DNA damage. Activated PARP cleaves NAD+ into nicotinamide and (ADP-ribose) and polymerizes the latter on nuclear acceptor proteins. Over-activation of PARP by reactive oxygen and nitrogen intermediates represents a pathogenetic factor in various forms of inflammation, shock, and reperfusion injury. Using a novel commercially available substrate, 6-biotin-17-nicotinamide-adenine-dinucleotide (bio-NAD+), we have developed three applications, enzyme cytochemistry, enzyme histochemistry, and cell ELISA, to detect the activation of PARP in oxidatively stressed cells and tissues. With the novel assay we were able to detect basal and hydrogen peroxide-induced PARP activity in J774 macrophages. We also observed that mitotic cells display remarkably elevated PARP activity. Hydrogen peroxide-induced PARP activation could also be detected in wild-type peritoneal macrophages but not in macrophages from PARP-deficient mice. Application of hydrogen peroxide to the skin of mice also induced bio-NAD+ incorporation in the keratinocyte nuclei. Hydrogen peroxide-induced PARP activation and its inhibition by pharmacological PARP inhibitors could be detected in J774 cells with the ELISA assay that showed good correlation with the traditional [3H]-NAD incorporation method. The bio-NAD+ assays represent sensitive, specific, and non-radioactive alternatives for detection of PARP activation.

Elevated rate of Thelper1 (TH1) lymphocytes and serum IFN-γ levels in psoriatic patients

Abstract Several disorders are known to be associated with altered Thelper1/Thelper2 (T H 1/T H 2) cytokine balance. Psoriasis is characterized by increased systemic and local production of T H 1 and pro-inflammatory cytokines. Furthermore recent data indicate the dominant presence of T H 1 lymphocytes in the circulation and T H 1 and Tcytotoxic1 (T C 1) cells in lesional skin of psoriatic patients. In order to assess the systemic T H 1/T H 2 imbalance in psoriasis most of the studies so far tested isolated peripheral mononuclear cells. As a new approach we applied a whole blood flow cytometric assay to determine the rate of circulating T H 1/T H 2 and T C 1/Tcytotoxic2 (T C 2) lymphocytes based on their intracellular IFN-γ, IL-4 and IL-10 expression. Besides, serum levels of these cytokines were determined in healthy controls and psoriatic patients by commercial ELISAs. In psoriatic patients we found significantly ( P + /IFN-γ + lymphocytes (30.3±8.8%) while the percent of CD4 + /IL-4 + cells (0.37±0.31%) were significantly ( P + /IFN-γ + : 20.1±7.3% and CD4 + /IL-4 + : 0.78±0.44%). The IL-10-positive CD4 + and CD8 + cells also had higher rate in psoriasis, but the difference between patients and controls was not significant, similarly to the rate of CD8 + /IFN-γ + and CD8 + /IL-4 + lymphocytes. Beside cellular expression, serum IFN-γ levels were also significantly higher (control: 4.9±6.4 pg/ml; psoriatic patients: 35.9±47.0 pg/ml; P H 1/T H 2 balance in psoriasis measured in non-separated whole blood T cells.

Nitric oxide‐peroxynitrite‐poly(ADP‐ribose) polymerase pathway in the skin

Abstract: In the last decade it has become well established that in the skin, nitric oxide (NO), a diffusable gas, mediates various physiologic functions ranging from the regulation of cutaneous blood flow to melanogenesis. If produced in excess, NO combines with superoxide anion to form peroxynitrite (ONOO–), a cytotoxic oxidant that has been made responsible for tissue injury during shock, inflammation and ischemia‐reperfusion. The opposite effects of NO and ONOO– on various cellular processes may explain the ‘double‐edged sword’ nature of NO depending on whether or not cellular conditions favour peroxynitrite formation. Peroxynitrite has been shown to activate the nuclear nick sensor enzyme, poly(ADP‐ribose) polymerase (PARP). Overactivation of PARP depletes the cellular stores of NAD+, the substrate of PARP, and the ensuing ‘cellular energetic catastrophy’ results in necrotic cell death. Whereas the role of NO in numerous skin diseases including wound healing, burn injury, psoriasis, irritant and allergic contact dermatitis, ultraviolet (UV) light‐induced sunburn erythema and the control of skin infections has been extensively documented, the intracutaneous role of peroxynitrite and PARP has not been fully explored. We have recently demonstrated peroxynitrite production, DNA breakage and PARP activation in a murine model of contact hypersensitivity, and propose that the peroxynitrite‐PARP route represents a common pathway in the pathomechanism of inflammatory skin diseases. Here we briefly review the role of NO in skin pathology and focus on the possible roles played by peroxynitrite and PARP in various skin diseases.

Increased frequency of intracellular interleukin (IL)-13 and IL-10, but not IL-4, expressing CD4+ and CD8+ peripheral T cells of patients with atopic dermatitis.

Summary Background  A number of studies exist demonstrating the increased expression of type 2 cytokines and decreased capacity to produce interferon‐γ (IFN‐γ) in peripheral blood mononuclear cells (PBMCs) of patients with atopic dermatitis (AD).

Is there penetration of titania nanoparticles in sunscreens through skin? A comparative electron and ion microscopy study

We report on a comparative study by Transmission Electron Microscopy (HRTEM) and Scanning Transmission Ion Microscopy (STIM) combined with Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-Ray Emission (PIXE) on ultra-thin and thin cross-sections, respectively, of various skin samples (porcine skin, healthy human skin, human skin grafted on a severe combined immuno-deficient mouse model) to which we applied topically various formulations containing titanium dioxide (TiO2) nanoparticles with primary particle sizes in the range from 20–100 nm. Whereas the HRTEM and STIM/PIXE images reveal clear differences – mainly related to the different thickness of the cross-sections – they unambiguously show that penetration of TiO2 nanoparticles is restricted to the topmost 3–5 corneocyte layers of the stratum corneum (SC).

Basophil CD63 expression assay on highly sensitized atopic donor leucocytes—a useful method in chronic autoimmune urticaria

Background  The autoimmune subclass of chronic idiopathic urticaria (CU) has been characterized by the occurrence of biologically relevant IgG antibodies against the IgE molecule or the α chain of the high‐affinity Fcɛ receptor (FcɛRIα) on basophils and mast cells. These antibodies are usually detected by autologous serum skin testing and confirmed by histamine release studies, immunoblotting, or enzyme‐linked immunosorbent assay, but not always.

Treatment of recalcitrant venous leg ulcers with autologous keratinocytes in fibrin sealant: a multinational randomized controlled clinical trial.

In a multicenter trial, the effect of a commercially available combination of autologous keratinocytes (3–6 × 106/mL) with fibrin sealant (Tissucol Duo S Immuno, Baxter Hyland Immuno) on the healing of recalcitrant venous leg ulcers (duration >3 months) was compared with standard care. The primary endpoint was time to healing, and the secondary endpoint was number of healed ulcers in both groups. Both groups received compression therapy with short‐stretch bandages. Forty‐four (38.3%) of the 116 patients who had BioSeed®‐S treatment achieved complete healing of the target ulcer compared with 24 (22.4%) of 109 patients who received standard treatment. The advantage for treatment with BioSeed®‐S over standard treatment was statistically significant (chi‐square test: p=0.0106). Time to complete healing of ulcers: the log‐rank test for equality over strata revealed a superiority of treatment with BioSeed®‐S+compression (median: 176 days) over compression+standard care (median >201 days) (p<0.0001). This study, to date the largest multicenter study with autologous keratinocytes, provides evidence for its efficacy in the treatment of patients with therapy‐resistant chronic venous leg ulcers.

Significant correlation between the CD63 assay and the histamine release assay in chronic urticaria

Background  Antibodies directed to the α subunit of the high affinity IgE receptor and the IgE molecule are proposed to be of pathogenetic relevance in a group of patients with chronic urticaria (CU). The diagnosis of autoimmune chronic urticaria (ACU) is difficult; the autologous serum skin test (ASST) seems to be a useful screening test, but reliable, additional confirmatory methods are needed.

Altered cytokine expression of peripheral blood lymphocytes in polymyositis and dermatomyositis

Objective: To investigate the intracellular and soluble cytokine levels and T cell subsets in peripheral blood of patients with active and inactive polymyositis and dermatomyositis. Methods: The frequencies of T and B lymphocytes, T helper (Th), and T cytotoxic (Tc) cells and of interferon γ (IFNγ), interleukin (IL)4, and IL10 expression of CD4+ or CD8+ cells were determined by flow cytometry. The concentrations of soluble cytokines were measured with commercial enzyme linked immunosorbent assays. Results: In active dermatomyositis there was a decreased percentage of T (CD3+) lymphocytes and Tc (CD8+) lymphocytes, decreased IFNγ expression of CD4+ and CD8+ cells, but an increase in B and IL4 producing CD4+ lymphocyte frequencies. These prominent changes disappeared in the inactive stage of the disease. In polymyositis no significant change in these lymphocyte subsets or in intracellular cytokine expression could be detected in either the active or the inactive form. The frequency of IL4+/IFNγ+ Th cells was calculated and a significantly increased Th2/Th1 frequency was found in active dermatomyositis, and a decreased frequency in inactive dermatomyositis, compared with the control population. Conclusions: There appears to be a difference between polymyositis and dermatomyositis in the level of peripheral blood lymphocytes and their intracellular cytokine content. These findings provide further evidence for a difference in the pathogenesis of polymyositis and dermatomyositis.