The role of keratinocyte cytokines in inflammation and immunity

Human relevance of in vivo and in vitro skin irritation tests for hazard classification of pesticides

Background: Test methods to inform hazard characterization and labeling of pesticides to protect human health are typically conducted using laboratory animals, and for skin irritation/corrosion the rabbit Draize test is currently required by many regulatory agencies. Although the Draize test is generally regarded to provide protective classifications for human health, new approach methodologies (NAMs) have been developed that offer more human relevant models that circumvent the uncertainty associated with species differences that exist between rabbits and humans. Despite wide applicability and use of these test methods across a broad range of chemicals, they have not been widely adopted for testing pesticides and pesticidal formulations. One of the barriers to adoption of these methods in this sector is low concordance with results from the Draize rabbit test, particularly for chemicals within the mild to moderate irritation spectrum.

Methods: This review compares and contrasts the extent to which available models used in skin irritation testing mimic the anatomy and physiology of human skin, and how each aligns with the known key events leading to chemically-induced adverse skin irritation and corrosion. Doing so fully characterizes the human relevance of each method.

Results: As alternatives to the rabbit Draize test, several protocols using ex vivo, in chemico, and in vitro skin models are available as internationally harmonized test guidelines. These methods rely on a variety of models of human skin, including excised rodent skin, synthetic biochemical models of barrier function, cell culture systems, and reconstructed human tissue models. We find these models exhibit biological and mechanistic relevance aligned with human skin irritation responses. Further, recent retrospective analyses have shown that the reproducibility of the Draize test is less than 50% for mild and moderate responses, with many of the replicate predictions spanning more than one category (e.g., a moderate response reported in one study followed by a non-irritant response reported in another study).

Conclusions: Based on this comparative evaluation, we recommend top-down and bottom-up testing strategies that use the most human relevant in vitro test methods for skin irritation and corrosion classification of pesticides and pesticide formulations. To further discriminate among mild and non-irritant formulations, optimization of a cytokine release protocol and subsequent analyses of reference formulation test results is recommended.

Humulus japonicus ameliorates irritant contact dermatitis by suppressing NF‑κB p65‑dependent inflammatory responses in mice

As a type of contact dermatitis (CD), irritant CD (ICD) is an acute skin inflammation caused by external irritants, such as soap, water and chemicals. Humulus japonicus (HJ) is a herbal medicine widely distributed in Asian countries and has anti-inflammatory, antimicrobial and antioxidant effects. The current study aimed to investigate the anti-dermatitis effect of HJ on ICD and determine the molecular basis of this effect using 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced dermatitis mice models and lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Mice were orally administered HJ and luteolin, the major compound in HJ, and topically administered TPA on the right ear to induce dermatitis. Topical application of TPA induced ear redness, oedema and increased infiltration of neutrophils and macrophages, which ameliorated following HJ and luteolin administration. The gene expression levels of inflammatory cell migrating chemokines, chemokine ligand 3 (CCL3) and chemokine (C-X-C motif) ligand 2 (CXCL2), and pro-inflammatory cytokine, IL-1β, were reduced in the ears of HJ- and luteolin-treated mice. HJ and luteolin also inhibited the gene expression of chemokines, CCL3 and CXCL2, and pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α, in LPS-stimulated RAW264.7 cells. Moreover, HJ and luteolin decreased the expression levels of two key inflammatory enzymes, cyclooxygenase-2 (COX2) and inducible nitric oxide synthase (iNOS), and total and active phosphorylation of NF-κB p65. These results suggest that HJ could have a protective effect against ICD by suppressing inflammatory responses; therefore, HJ is a promising therapeutic strategy for ICD treatment.

Sebaceous immunobiology - skin homeostasis, pathophysiology, coordination of innate immunity and inflammatory response and disease associations

This review presents several aspects of the innovative concept of sebaceous immunobiology, which summarizes the numerous activities of the sebaceous gland including its classical physiological and pathophysiological tasks, namely sebum production and the development of seborrhea and acne. Sebaceous lipids, which represent 90% of the skin surface lipids in adolescents and adults, are markedly involved in the skin barrier function and perifollicular and dermal innate immune processes, leading to inflammatory skin diseases. Innovative experimental techniques using stem cell and sebocyte models have clarified the roles of distinct stem cells in sebaceous gland physiology and sebocyte function control mechanisms. The sebaceous gland represents an integral part of the pilosebaceous unit and its status is connected to hair follicle morphogenesis. Interestingly, professional inflammatory cells contribute to sebocyte differentiation and homeostasis, whereas the regulation of sebaceous gland function by immune cells is antigen-independent. Inflammation is involved in the very earliest differentiation changes of the pilosebaceous unit in acne. Sebocytes behave as potent immune regulators, integrating into the innate immune responses of the skin. Expressing inflammatory mediators, sebocytes also contribute to the polarization of cutaneous T cells towards the Th17 phenotype. In addition, the immune response of the perifollicular infiltrate depends on factors produced by the sebaceous glands, mostly sebaceous lipids. Human sebocytes in vitro express functional pattern recognition receptors, which are likely to interact with bacteria in acne pathogenesis. Sex steroids, peroxisome proliferator-activated receptor ligands, neuropeptides, endocannabinoids and a selective apoptotic process contribute to a complex regulation of sebocyte-induced immunological reaction in numerous acquired and congenital skin diseases, including hair diseases and atopic dermatitis.

Interleukin-1α and Interleukin-8 Release by Human Keratinocyte Cell Culture Treated with Surfactants

The effects of four cosmetic surfactants on interleukin (IL)-1α and IL-8 release from human keratinocytes were studied to investigate the feasibility of using these effects for the prediction of the irritation potential of chemicals. After exposure of cells to surfactants, the amounts of IL-1α and IL-8 released into culture medium were measured by ELISA. Cytotoxicity was evaluated by using the neutral red uptake (NRU) cytotoxicity assay. Cytokine release was increased 7–15 times by sodium lauryl sulphate (SLS), laurtrimonium chloride, cocamidopropyl betaine (CPB) and Oleth-5 at cytotoxic concentrations. IL-8 release was increased 3–4 times by SLS, CPB and Oleth-5 at subcytotoxic concentrations. After exposure to SLS, IL-1α was released within 1 hour, suggesting that IL-1α release is associated with membrane damage, whereas IL-8 release continued for 24 hours, suggesting that IL-8 was produced within the cells. Cytotoxicity tests and IL-8 release assays were also performed on seven other surfactants. The results show that moderate irritants CPB and PEG-4 dioleate, which have weak cytotoxic effects, significantly increased IL-8 release from human keratinocytes. It is suggested that measurement of IL-8 release is useful for predicting the irritation potential of chemicals which cannot be detected by using the NRU cytotoxicity assay.

Microfluidics-based skin irritation test using in vitro 3D angiogenesis platform

A global ban on animal experiments has been proposed. Hence, it is imperative to develop alternative models. Artificial skin models should reflect the responses of subcutaneous blood vessels and the immune system to elucidate disease and identify cosmetics' base materials. Notably, in vivo skin-irritation cascades involve disruption of the epidermal barrier and the release of proinflammatory mediators in response to chemical stimuli. Such proinflammatory factors promote angiogenesis and blood vessel permeability, as observed in irritant contact dermatitis. As an alternative to animal models, we propose a novel skin-irritation model based on a three-dimensional in vitro angiogenesis platform, in which irritated keratinocytes biochemically stimulate vascular endothelial growth factors. Our microfluidic platform hosts interactions between keratinocytes and dermal fibroblasts, which promote angiogenic sprouting. We use sodium lauryl sulfate (SLS) and steartrimonium chloride (SC) as chemical irritants. The irritative effects of SLS and SC are of particular interest due to the ubiquity of both SLS and SC in cosmetics. SLS was observed to significantly affect angiogenic performance, with increasing sprout length. Further promotion of vessel sprouting and lumen formation was observed with 10, 20, and 60 μM of SC, despite its classification as nonirritating and use in supposedly safe formulations. This platform provides an alternative to animal testing as a basis for testing cosmetics and pharmaceutical substances, in addition to serving as a disease model for irritant contact dermatitis.

IL6Rα function in myeloid cells modulates the inflammatory response during irritant contact dermatitis

Irritant contact dermatitis (ICD) is characterized by epidermal hyperplasia, infiltration of leucocytes into lesional skin and inflammatory cytokine release. The cellular infiltrate during ICD comprises primarily cells of the myeloid lineage. Our group has previously shown that the cytokine IL-6 confers a protective effect to lesional skin during ICD. How IL-6Rα function in myeloid cells is involved in the inflammatory response during ICD is, however, unknown. In the present study, utilizing a chemical model of ICD, it is shown that mice with a myeloid-specific knockout of the IL-6Rα (IL-6Rα^Δmyeloid ) display an exaggerated inflammatory response to benzalkonium chloride (BKC) and Jet propellant-8 (JP8) fuel, two well-characterized irritants relative to littermate control. Results from immunohistochemical and flow cytometric analyses revealed that IL-6Rα^Δmyeloid mouse skin displayed increased epidermal hyperplasia and inflammatory monocyte influx into lesional skin but lower numbers of resident macrophages relative to littermate controls after irritant exposure. Multiplex immunoassay revealed significantly higher levels of pro-inflammatory cytokines IL-1α and TNF-α, but reduced expression of chemokine proteins including CCL2-5, CCL7, CCL11, CXCL1 and CXCL10 in IL-6Rα^Δmyeloid mouse skin relative to littermate control following irritant exposure. These results highlight a previously unknown role of IL-6Rα function in myeloid cells in modulating the inflammatory response and myeloid population dynamics during ICD.

Expression of suppressor of cytokine signaling 3 (SOCS3) and interleukin-6 (-174-G/C) polymorphism in atopic conditions

Hypersensitivity of the immune system is caused by elevated immunoglobulin E (IgE) levels in the serum, in response to a discrete allergen leading to allergic reactions. IgE-mediated inflammation is regulated by the cascade of defense related signaling molecules including interleukin-6 (IL-6) that plays pivotal role in the survival and maturation of mast cells during an allergic reaction. IL-6 mediated defense responses are tightly regulated by Suppressor of Cytokine Signaling 3 (SOCS3), an inhibitory molecules of Janus Kinase-Signal Transducers and Activators of Transcription (JAK-STAT) signaling, in a negative feedback mechanism. The given study focuses on the assessment of crosstalk between SOCS3 and IL-6 to unravel the molecular significance of SOCS3 and IL-6 in the diagnosis and prognosis of allergy. The expression study of SOCS3 through real-time PCR analysis revealed, a 5.9 mean fold increase in SOCS3 expression in atopic cases in comparison to control cases. Moreover, IL-6 has, also, been found significantly enhanced in the serum level of atopic cases (26.4 pg/ml) as compared to control cases (3.686 pg/ml). Female population was found to be at a higher risk to develop atopic condition than male population as females exhibited higher expression of both SOCS3 and IL-6 than males. Furthermore, the polymorphic study of IL-6 promoter region (IL-6 174-G/C) in atopic population has reasserted the importance of SOCS3 and IL-6 in the diagnosis and prognosis of allergy. Expression of SOCS3 and IL-6 serum levels were found to be highly correlated. Therefore establishing the role of IL-6 (-174-G/C) polymorphism on the expression of SOCS3 and IL-6 in atopic cases. Notably, the study established SOCS3 and IL-6 as potential targets for the diagnosis/prognosis of allergy and for the development of reliable therapeutic strategies to control atopic conditions in the near future.

Keratinocyte-specific deletion of the IL-6RΑ exacerbates the inflammatory response during irritant contact dermatitis

Irritant Contact Dermatitis (ICD) is the most common occupational skin disorder. During ICD, keratinocytes initiate the inflammatory cascade by producing cytokines including IL-6. This laboratory previously reported that IL-6 deficiency exacerbates skin inflammation during ICD, yet the role of the IL-6Rα in keratinocyte function has yet to be elucidated. To investigate how IL-6Rα function in keratinocytes influences the inflammatory response during ICD, keratinocyte-specific IL-6Rα KO (IL6ra^Δker) and WT mice were exposed to two well-known occupational irritants; JP-8 jet fuel, and benzalkonium chloride (BKC), or acetone control for three days. Dermatitis lesions were collected and flow cytometric and immunohistochemical analyses revealed that IL6ra^Δker skin displayed increased populations of CD11b⁺CD45⁺ and F4/80⁺ cells respectively relative to WT. However, IL6ra^Δker mouse skin contained reduced numbers of γδ T cells relative to WT. Furthermore, IL6ra^Δker skin expressed increased levels of pro-inflammatory cytokines including IL-1β, IL-22, and CCL4 but decreased levels of anti-inflammatory cytokines IL-4 and IL-10. These results indicate that epidermal keratinocyte IL-6Rα function modulates epidermal hyperplasia, immune cell infiltration into skin and cytokine expression during ICD and suggests that the previously reported protective effect of IL-6 during ICD might be mediated primarily by keratinocyte derived IL-6Rα.

Gentiana scabra Bunge roots alleviates skin lesions of contact dermatitis in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The roots and rhizomes of Gentiana scabra Bunge in the family Gentianaceae comprise a major herbal medicine for skin diseases caused by wind-heat or dampness-heat in China, Japan and Korea. This treatment can clear away heat and dry dampness and purge fire from the liver and gallbladder.

AIM OF THE STUDY

This study was designed to investigate the therapeutic potential and anti-inflammatory effects of G. scabra, roots and rhizomes.

MATERIALS AND METHODS

Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) revealed the presence of gentiopicrin in the roots and rhizomes of G. scabra. We then investigated the effects of ethanol extract of G. scabra, roots and rhizomes (EEGS) on skin lesions and thickness, erythema and melanin index, histopathological abnormalities, and cytokine and chemokine production in mice with contact dermatitis (CD) induced by 1-fluoro-2,4-dinitrofluorobenzene (DNFB). Moreover, the effects of EEGS on body weights and spleen body weight ratio were evaluated.

RESULTS

Topical application of EEGS alleviated skin lesions such as surface roughness, excoriations and scabs on the skin of CD mice, as well as prevented skin enlargement, and lowered the erythema and melanin index. In addition, EEGS prevented hyperkeratosis, epidermal hyperplasia and immune cell infiltration, and inhibited TNF-α, IFN-γ, IL-6 and MCP-1 production in inflamed tissues. EEGS did not affect changes in body weights and spleen body weight ratio in contrast to dexamethasone.

CONCLUSIONS

These data indicate that the roots and rhizomes of G. scabra can be used as anti-inflammatory agents for CD with relative safety and that its therapeutic mechanisms are related to regulation of pro-inflammatory cytokines such as TNF-α and IFN-γ.

Extracellular vesicles derived from Malassezia furfur stimulate IL-6 production in keratinocytes as demonstrated in in vitro and in vivo models

BACKGROUND

Malassezia is one of the commensal microorganisms colonized on human skin and has been shown to be related to several inflammatory cutaneous disorders. Previous studies indicated that Malassezia. sympodialis (M. sympodialis) can produce extracellular vesicles, however, the immunoregulatory function of Malassezia extracellular vesicles on keratinocytes has not been studied.

OBJECTIVE

To investigate the extracellular vesicular production capability of Malassezia. furfur (M. furfur) and examine their immunoregulatory effects both in vitro and in vivo.

METHODS

Extracellular vesicles derived from M. furfur were isolated by sequential ultracentrifugation procedure. Their structure and diameter were determined by negative stain TEM and NTA, respectively. Confocal microscopy was used to visualize the internalization of these nanoparticles into HaCaT cells and mice epidermal keratinocytes. The expressions of inflammatory cytokines were screened using PCR Array assay and validated in vitro by qPCR and ELISA assays. In vivo cytokine production was measured by the IHC method. The role of NF-κB in such process was evaluated in HaCaT cells by western blot assay.

RESULTS

Our results showed that M. furfur produced ovoid-shaped nanoparticles, which could be then internalized into HaCaT cells, as well as mice epidermal keratinocytes. IL-6 expression was significantly enhanced in response to extracellular vesicular stimulation both in vitro and in vivo, in which process the activation of NF-κB was involved.

CONCLUSION

M. furfur has the ability to release extracellular vesicles, which can be internalized into keratinocytes and promote the production of IL-6 with the involvement of NF-κB dependent pathway. Such findings reveal some important new insights into Malassezia pathogenesis and therapy.

In vitro characterization of cutaneous immunotoxicity of immortalized human keratinocytes (HaCaT) exposed to reactive and disperse textile dyes

Several synthetic dyes are used by textile industry for supplying the market of colored clothes. However, these chemicals have been associated with a variety of adverse human health effects, including textile dermatitis. Thus, there is a growing concern to identify textile dyes potentially as skin immunotoxicants. The aim of this in vitro study was to characterize the immunotoxic potential of reactive (Reactive Green 19 [RG19], Reactive Blue 2 [RB2], Reactive Black 5 [RB5]) and disperse (Disperse Red 1 [DR1]) textile dyes using a dermal cell line. For this purpose, a cell-based approach was conducted with immortalized human keratinocytes (KC) (HaCaT) using selected biomarkers of cutaneous inflammation including modulation of matrix metalloproteinases (MMP), oxidative stress such as reactive oxygen species (ROS) generation, and inflammatory cytokine profile. DR1 was the only dye able to trigger an immune response such as release of IL-12 cytokine, a potent co-stimulator of T helper 1 cell, which may be considered as a skin immunotoxicant. The reactive dyes including RB5 that were previously reported as skin sensitizers failed to induce inflammatory reactions under the conditions tested. The reactive dyes studied may pose a risk to human KC by induction of effects related to modulation of MMP-2 (RB5) and -9 (RB5 and RB2) and generation of ROS (RG19 and RB2). Thus, all these dyes need to be used with caution to avoid undesirable effects to consumers who may be exposed dermally.

Sebum lipids influence macrophage polarization and activation

BACKGROUND

As lipids are known to regulate macrophage functions, it is reasonable to suppose that a sebocyte-macrophage axis mediated by sebum lipids may exist.

OBJECTIVES

To investigate if sebocytes could contribute to the differentiation, polarization and function of macrophages with their secreted lipids.

METHODS

Oil Red O lipid staining and Raman spectroscopy were used to assess the dermal lipid content and penetration. Immunohistochemistry was used to analyse the macrophage subsets. Human peripheral blood monocytes were differentiated in the presence of either supernatant from human SZ95 sebocytes or major sebum lipid components and activated with Propionibacterium acnes. Macrophage surface markers and their capacity to uptake fluorescein isothiocyanate-conjugated P. acnes were detected by fluorescence-activated cell sorting measurements. Cytokine protein levels were evaluated by enzyme-linked immunosorbent assay and Western blot analysis.

RESULTS

Sebaceous gland-rich skin had an increased dermal lipid content vs. sebaceous gland-poor skin to which all the tested sebum component lipids could contribute by penetrating the dermoepidermal barrier. Of the lipids, oleic acid and linoleic acid promoted monocyte differentiation into alternatively activated macrophages. Moreover, linoleic acid also had an anti-inflammatory effect in P. acnes-activated macrophages, inhibiting the secretion of interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α. Squalene, palmitic acid, stearic acid and oleic acid augmented the secretion of IL-1β, even in the absence of P. acnes, whereas oleic acid had a selective effect of inducing IL-1β but downregulating IL-6 and TNF-α secretion.

CONCLUSIONS

Our results suggest a role for sebaceous glands in modulating innate immune responses via their secreted lipids that are of possible pathological and therapeutic relevance.

Imaging of Abdominal and Pelvic Manifestations of Graft-Versus-Host Disease After Hematopoietic Stem Cell Transplant

OBJECTIVE

Graft-versus-host disease (GVHD) is a common complication of hematopoietic stem cell transplant (HSCT). GVHD predominantly affects the skin, gastrointestinal system and hepatobiliary systems. Imaging findings in the gastrointestinal tract include bowel wall thickening with mucosal enhancement, mesenteric edema, and vascular engorgement. In the hepatobiliary system, hepatosplenomegaly, periportal edema, bile duct dilatation, and gallbladder and biliary wall thickening are seen. Although the imaging findings of GVHD are nonspecific, with a known history of HSCT, GVHD should be considered.

CONCLUSION

GVHD is a serious complication of HSCT, which involves multiple organ systems, with imaging manifestations most commonly seen in the gastrointestinal tract and hepatobiliary system. Knowledge of the imaging manifestations of GVHD, which alone may be relatively nonspecific, taken in conjunction with clinical history including the timing and type of HSCT, laboratory values, stool studies, and dermatologic findings can increase radiologist confidence in suggesting this diagnosis.

Safer topical treatment for inflammation using 5α-tetrahydrocorticosterone in mouse models

Use of topical glucocorticoid for inflammatory skin conditions is limited by systemic and local side-effects. This investigation addressed the hypothesis that topical 5α-tetrahydrocorticosterone (5αTHB, a corticosterone metabolite) inhibits dermal inflammation without affecting processes responsible for skin thinning and impaired wound healing. The topical anti-inflammatory properties of 5αTHB were compared with those of corticosterone in C57Bl/6 male mice with irritant dermatitis induced by croton oil, whereas its effects on angiogenesis, inflammation, and collagen deposition were investigated by subcutaneous sponge implantation. 5αTHB decreased dermal swelling and total cell infiltration associated with dermatitis similarly to corticosterone after 24 h, although at a five fold higher dose, but in contrast did not have any effects after 6 h. Pre-treatment with the glucocorticoid receptor antagonist RU486 attenuated the effect of corticosterone on swelling at 24 h, but not that of 5αTHB. After 24 h 5αTHB reduced myeloperoxidase activity (representative of neutrophil infiltration) to a greater extent than corticosterone. At equipotent anti-inflammatory doses 5αTHB suppressed angiogenesis to a limited extent, unlike corticosterone which substantially decreased angiogenesis compared to vehicle. Furthermore, 5αTHB reduced only endothelial cell recruitment in sponges whereas corticosterone also inhibited smooth muscle cell recruitment and decreased transcripts of angiogenic and inflammatory genes. Strikingly, corticosterone, but not 5αTHB, reduced collagen deposition. However, both 5αTHB and corticosterone attenuated macrophage infiltration into sponges. In conclusion, 5αTHB displays the profile of a safer topical anti-inflammatory compound. With limited effects on angiogenesis and extracellular matrix, it is less likely to impair wound healing or cause skin thinning.

Potential applications of keratinocytes derived from human embryonic stem cells

Although skin grafting is one of the most advanced cell therapy technique, wide application of skin substitutes is hampered by the difficulty in securing sufficient amount of epidermal substitute. Additionally, in understanding the progression of skin aging and disease, and in screening the cosmetic and pharmaceutical products, there is lack of a satisfactory human skin-specific in vitro model. Recently, human embryonic stem cells (hESCs) have been proposed as an unlimited and reliable cell source to obtain almost all cell types present in the human body. This review focuses on the potential off-the-shelf use of hESC-derived keratinocytes for future clinical applications as well as a powerful in vitro skin model to study skin function and integrity, host-pathogen interactions and disease pathogenesis. Furthermore, we discuss the industrial applications of hESC-derived keratinized multi-layer epithelium which provides a human-like test platform for understanding disease pathogenesis, evaluation of new therapeutic modalities and assessment of the safety and efficacy of skin cosmetics and therapeutics. Overall, we conclude that the hESC-derived keratinocytes have great potential for clinical, research and industrial applications.

Association of disease severity with IL-1 levels in methotrexate-treated psoriasis patients

Interleukin-1 plays a key role in inflammation and keratinocyte activation. It is an important mediator in the initiation and maintenance of psoriatic plaques and may represent an attractive therapeutic target. The aim of this study is to evaluate the effect of Methotrexate (MTX) on IL-1 α and IL-1 β levels in both plasma and skin biopsy of patients with psoriasis and to investigate their association with clinical disease activity. Forty-five control subjects and 58 patients with psoriasis were recruited for this study. The patients were treated with 7.5 mg of MTX per week for 12 weeks. Folic acid was given at 5 mg once daily except on the day of MTX for 12 weeks. Blood samples and lesional skin biopsy were taken. Disease severity was assessed by Psoriasis Area Severity Index (PASI) score. IL-1 levels in plasma and skin biopsy were analysed using ELISA. PASI score declined significantly (P < 0.001) from day 0 to 12 weeks of MTX treatment. IL-1 α level in plasma and skin biopsy was reduced at day 0 sample and elevated significantly (P < 0.001) after MTX treatment. IL-1β level in plasma and skin biopsy was higher at day 0 sample and reduced significantly (P < 0.001) after MTX treatment. IL-1α levels and PASI score showed inverse correlation score before and after treatment with MTX. Whereas IL-1β levels showed positive correlation before and after treatment with MTX. Decreasing IL-1β levels by MTXs in psoriasis may block the Th17 differentiation. This shows the therapeutic effect of MTX in controlling the immunopathogenesis of psoriasis.

Cytokines and chemokines in irritant contact dermatitis

Irritant contact dermatitis is a result of activated innate immune response to various external stimuli and consists of complex interplay which involves skin barrier disruption, cellular changes, and release of proinflammatory mediators. In this review, we will focus on key cytokines and chemokines involved in the pathogenesis of irritant contact dermatitis and also contrast the differences between allergic contact dermatitis and irritant contact dermatitis.

The Use of In Vitro Systems for Evaluating Immunotoxicity: The Report and Recommendations of an ECVAM Workshop

This is the report of a workshop organised by the European Centre for the Validation of Alternative Methods (ECVAM). ECVAM's main goal, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods that are of importance to the biosciences and which replace, reduce or refine the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures that would enable it to become well informed about the state-of-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organization of ECVAM workshops on specific topics, at which small groups of invited experts would review the current status of various types of in vitro tests and their potential uses, and make recommendations about the best ways forward (Anonymous, 1994). The workshop on "The use of in vitro systems for evaluating Immunotoxicity" was held at ECVAM (Ispra), Italy, on 24th-26th November 2003. The participants represented academia, national organizations, international regulatory bodies and industry. The aim of the workshop was to review the state-of-the-art in the field of in vitro immunotoxicology, and to develop strategies towards the replacement of in vivo testing. At the end of this report are listed the recommendations that should be considered for prevalidation and validation of relevant and reliable procedures, that could replace the use of animals in chemical and cosmetics toxicity testing.

Use of a serum-free reconstituted epidermis as a skin pharmacological model

This study is aimed at assessing some of the possibilities offered by a new kind of three-dimensional skin culture in the field of toxicity and skin inflammation. The Reconstituted Epidermis used is presently the only skin model on the market in which normal human keratinocytes are allowed to grow and to differentiate in a chemically defined culture medium. The response of this original tissue to chemical (anionic and cationic surfactants) and physical (UVB radiation) insults was compared with human keratinocytes in monolayer culture and assessed through histological analysis, cell viability quantification and interleukin-1alpha (IL-1alpha) release measurement. For the surfactants and the UVB radiation a clear relationship was shown between the amount of IL-1alpha released and both the cell viability and the histological appearance of the skin. Sublethal doses of UV radiation induced exclusively an increase of intracellular amount of IL-1alpha, the magnitude of which seemed to be time dependent. The irritating potential of various kinds of cosmetic creams was then assessed using this skin model and compared with human irritation data. The intensity of erythema and oedema induced by a 48-hr human patch test was consistent with the amount of IL-1alpha secreted in the medium, the histological appearance of the Reconstituted Epidermis and the cell viability.

Impact of tumour necrosis factor-α polymorphisms on irritant contact dermatitis

BACKGROUND

Genetic variations in genes coding for cytokines involved in skin inflammation may alter their expression, thus changing the susceptibility to irritant contact dermatitis (ICD).

OBJECTIVES

To determine the prevalence of polymorphisms in the cytokine genes TNFA-238 and TNFA-308 in patients with occupational ICD, and to compare it with that in controls.

METHODS

In a case-control study, 478 patients with occupational ICD of the hands were genotyped for TNFA-238 and TNFA-308 polymorphisms. The results were compared with those for 393 apprentices from the same high-risk occupations (controls).

RESULTS

For a carrier of a variant TNFA-238A allele, the odds ratio (OR) of acquiring ICD was 0.57 [95% confidence interval (CI) 0.34-0.97], suggesting a protective effect of the A allele. The genotype distributions were 94.4% wild type (G/G), 5.6% heterozygous (G/A) and 0% homozygous for variant allele (A/A) in patients, and 90.9%, 8.5%, and 0.6%, respectively in controls. In contrast, carriers of the variant TNFA-308A allele had an increased risk of ICD [OR 1.33; 95% CI 1.05-1.74; G/G 66.4%, G/A 31.2%, and A/A 2.4% (patients) versus 73.5%, 24.6%, 1.9% in controls].

CONCLUSIONS

Individuals with a TNFA-238 polymorphism are less prone and those with a TNFA-308 polymorphism are more prone to develop ICD of the hands, suggesting a protective versus a detrimental effect of the A allele respectively.

Hexavalent chromium induced ROS formation, Akt, NF-kappaB, and MAPK activation, and TNF-alpha and IL-1alpha production in keratinocytes

In certain cell types, it has been found that, hexavalent chromium could increase ROS formation, activate cell signaling and stimulate the release of cytokines. But, in keratinocytes, these effects have not yet fully been demonstrated. Our aim is to observe the above effects of hexavalent chromium on keratinocytes. By utilizing HaCaT cells and the skin of albino guinea pigs, we showed that hexavalent chromium could increase ROS formation, activate the Akt, NF-kB, and MAPK pathways as well as increase the production of cytokines, including TNF-alpha and IL-1alpha. The release of these cytokines from keratinocytes is considered to be a key participant in the pathogenesis of contact hypersensitivity. Among cement workers, chromium hypersensitivity is an important occupational skin disease issue. Therefore, the observations of our study help us better understand the role of hexavalent chromium on the development of chromium hypersensitivity, which might provide clues for clinicians in the development of chemopreventative agents for the prevention of chromium hypersensitivity among cement workers.

Zingiber officinale protects HaCaT cells and C57BL/6 mice from ultraviolet B-induced inflammation

Ultraviolet (UV) light is a physical carcinogen, and UV irradiation from sunlight has negative effects on human skin. UVB-induced inflammation is linked to excessive induction of various inflammatory cytokines/chemokines in many types of cells, including keratinocytes. The purpose of this study was to investigate the anti-inflammatory effect of water extract of Zingiber officinale, gingerol, and shogaol on UVB-induced skin damage in the human keratinocyte cell line HaCaT and C57BL/6 mice. To test for an effective compound to protect against inflammation in UV-damaged skin, we prepared a water extract of ginger rhizomes and examined the effects of Z. officinale, gingerol, and shogaol on cell viability and cytokine/chemokine production in UV-irradiated HaCaT cells. We also investigated the in vivo relevance of these findings in C57BL/6 mice using hematoxylin and eosin staining and cytokine measurements. A water extract of Z. officinale, gingerol, and shogaol inhibited production of cytokines in UVB-irradiated HaCaT cells effectively. Treatment with Z. officinale attenuated UVB-induced hyperplasia, infiltration of leukocytes, and dilation of blood vessels in the dermis of mice. Z. officinale, gingerol, and shogaol show potential as anti-inflammatory agents to protect skin against UVB irradiation damage.

Development of an in vitro model for radiation-induced effects on oral keratinocytes

Changes in epithelial cell activity and the production of pro-inflammatory cytokines were examined utilizing an organotypic culture system as an in vitro model to study the effects of radiation on oral keratinocytes to simulate what is thought to occur in radiation-induced oral mucositis. Monolayer cultures of oral keratinocyte were irradiated by varying the dose. Cell injury was assessed using a colony forming efficiency (CFE) assay. Third passage oral keratinocytes were seeded onto AlloDerm to form a 3D construct of an ex vivo produced oral mucosa equivalent (EVPOME) which was irradiated with 0, 1, 3 and 8Gy. Formalin-fixed sections of the EVPOME were used for histology and immunohistochemistry to examine proliferative capacity. Epithelial cell viability of EVPOME was measured by MTT assay. Spent culture medium was used to determine post-radiation pro-inflammatory cytokine production. Basal cells became more swollen and pyknotic as radiation increased, implying loss of cell viability also determined by MTT assay. The number of Ki-67 immunopositive cells and CFE showed negative correlation with radiation, indicating loss of cell proliferative capacity. The production of pro-inflammatory cytokines, IL-1alpha and IL-8, tended to increase in a radiation dose dependent manner. The EVPOME lacking submucosal cellular components was a useful model.

Effects of a Brazilian herbal compound as a cosmetic eyecare for periorbital hyperchromia ("dark circles")

BACKGROUND

Evidence suggests that periorbital hyperchromia (dark circles) occurs mainly as a consequence of postinflammatory hemodynamic congestion producing a typical bruising aspect on the lower eyelids.

AIMS

To evaluate the clinical effects of Pfaffia paniculata/Ptychopetalum olacoides B./Lilium candidum L.-associated compound (PPLAC) on periorbital hyperchromia and to study in vitro its underlying anti-inflammatory and antioxidant mechanisms.

METHODS

Twenty-one volunteers presenting with periorbital hyperchromia received a serum sample containing 5.0% PPLAC, which was applied topically in the periorbital area twice a day for 28 days. Skin color was measured using variations in the individual typological angle (DeltaITA(0)) and skin luminance (DeltaL*) calculated in the area around the eyes and in the adjacent area. Colorimetric readings were taken at the onset and end of the 28-day treatment. Volunteers were also asked to fill out a questionnaire concerning the improvement in "dark circles." The anti-inflammatory and antioxidant effects of PPLAC were measured by quantification of prostaglandin E(2), leukotriene B(4), histamine, and superoxide dismutase levels using an in vitro model of human skin culture.

RESULTS

Topical application of PPLAC led to a significant improvement in skin luminance and tone in the periorbital area, which was demonstrated by increased values of ITA(0) and L* in about 90% of volunteers. In addition, subjects reported reduced intensity and improved appearance of "dark circles." A dose-dependent decreased production of inflammatory mediators, concomitant to increased antioxidant enzyme levels, was observed in our in vitro studies, under basal and lipopolysaccharide-stimulated conditions.

CONCLUSIONS

Although the precise mechanisms related to PPLAC remain to be clarified, our results indicate that the reduction in the inflammatory process as well as the antioxidant protection against deleterious elements may be considered as an integral approach to preserve the integrity of vascular endothelium, preventing the hemodynamic congestion that culminates in the formation of "dark circles" around the eyes.

Pathology of graft-versus-host disease in the gastrointestinal tract

Graft-versus-host disease (GVHD), a common complication of hematopoietic stem cell transplantation, is a clinical syndrome that requires synthesis of clinical, laboratory, and histopathologic findings for diagnosis. The gastrointestinal (GI) tract is commonly affected, and pathologists must recognize subtle morphologic alterations in GI mucosal biopsies to make the diagnosis and to rule out other causes of GI dysfunction such as cytomegalovirus infection and drug effects. This review summarizes the histopathologic features of GVHD in the GI tract and outlines recent recommendations for reporting of GI biopsies with suspected GVHD.

[Immunology of allergic contact dermatitis]

Eczema is one of the most common skin diseases in dermatological practice. The broad medical definition of eczema includes any acute but non-infectious inflammatory reaction of the skin. The relative homogeneity of both the clinical and histological manifestations of eczema is in stark contrast to the profound pathogenetic differences of its various forms. The group of contact dermatitis can be divided into two main categories: irritant and allergic. Irritant contact dermatitis is due to a principally non- immunological inflammatory reaction of the skin to various physical or chemical irritants. In sharp contrast, allergic contact dermatitis is an antigen-specific cellular immune response of the skin, which in general requires prior antigen-recognition and priming of immune cells. A comprehensive understanding of the complex interactions between immune cells, inflammatory mediators and adhesion molecules in the underlying pathogenesis of allergic contact dermatitis is key for a better functional understanding and the development of new therapeutic strategies.

G2A plays proinflammatory roles in human keratinocytes under oxidative stress as a receptor for 9-hydroxyoctadecadienoic acid

G2A is a stress-inducible G protein-coupled receptor for oxidized free fatty acids, such as 9-hydroxyoctadecadienoic acid (HODE). As skin is routinely and pathologically exposed to many oxidative stresses such as UV radiation, chemical agents, and inflammation that might induce both G2A expression and production of G2A ligands, we examined G2A function in human keratinocytes. G2A was expressed in human epidermis, normal human epidermal keratinocytes (NHEK), and an immortalized human keratinocyte cell line (HaCaT). 9(S)-HODE evoked intracellular calcium mobilization and secretion of cytokines, including IL-6, IL-8, and GM-CSF in NHEK cells. These responses became prominent in HaCaT cells by overexpression of G2A. 9(S)-HODE inhibited proliferation of NHEK cells by suppressing DNA synthesis and arresting the cell cycle in the G0/1-phase. On the other hand, 13(S)-HODE, another major oxidative product from linoleate, showed little or no effect on either cytokine secretion or on proliferation in NHEK cells. A small interfering RNA designed to downregulate G2A caused suppression of 9(S)-HODE-induced inhibitory effects on proliferation of NHEK cells. UVB and H(2)O(2) induced G2A expression and caused oxidation of linoleate to produce 9-HODE in HaCaT cells. These results suggest that 9-HODE-G2A signaling plays proinflammatory roles in skin under oxidative conditions.

Interplay among oxidants, antioxidants, and cytokines in skin disorders: Present status and future considerations

The pathogenicity of skin disorders involves a complexity of physiological, immunological, environmental, and genetic phenomena. This review focuses on cross-talks between two main agents, the oxidants and cytokines network, which have recently been found to play important roles in the pathophysiology of a large variety of skin disorders, including carcinogenesis, UVB irradiation damages, inflammatory processes, and a series of diseases such as, psoriasis, pyoderma gangrenosum, atopic dermatitis, irritant contact dermatitis, and bacterial skin infections. In particular the review discusses the question how an interplay between oxidants and cytokines might be beneficial in wound-healing and in therapeutic strategies in clinical settings. These involve topical applications and oral administration of antioxidant and inflammatory-cytokines-neutralizing antibodies. Monitoring cytokine expression in skin disorders (inflammatory versus anti-inflammatory, or Th1 versus Th2 types of cytokines) will definitely help to evaluate the severity of injury, its type, and its role in therapy. Furthermore, it is expected that future studies should explore the possible roles of the synergistic interactions between antioxidants and cytokines and their impact on the Th1/Th2 cytokine networks balances.

IL-4 suppresses UVB-induced apoptosis in skin

In this study, cutaneous role of IL-4 in UVB-induced apoptosis was investigated using transgenic mice with skin-specific expression of IL-4 (IL-4 Tg mice). The transgenic mice did not show any gross clinical abnormalities. However, epidermis was thickened and increased MHC class II positive cells were detected as well as enhanced expression of inflammatory cytokines such as IL-1 and TNF-alpha in skin. In addition, histological analysis revealed increased infiltration of lymphocytes, acanthosis, hyperkeratosis, and parakeratosis in skin of IL-4 Tg mice. The physiological effect of IL-4 overexpression in skin against environmental stimulus such as UVB was investigated by irradiating wild-type and IL-4 Tg mice with UVB followed by evaluation of apoptosis. The result demonstrated suppressed apoptosis in epidermis of IL-4 Tg mice compared with wild-type mice. To further assess anti-apoptotic function of IL-4 in keratinocytes, stable cell clones were made where IL-4 was constitutively overexpressed and examined for UVB-induced apoptosis. The results showed that apoptosis was remarkably decreased in IL-4 over-expressing cell clones compared with that in mock transfected cells. Collectively, data presented here shows that IL-4 has an inhibitory effect against UVB-induced apoptosis in keratinocytes, suggesting that IL-4 may be an important regulator in cutaneous immunity against UVB.

Determination of interleukin-1α in human NCTC 2544 keratinocyte cells as a predictor of skin irritation from lysine-based surfactants

Lysine derivative surfactants are a class of amino acid-based surfactants synthesized as lecithin analogues that deserve particular attention because of their low toxicity and high biocompatibility. To complete the toxicological profile of these surfactants, IL-1 alpha production (cell-associated and release to the culture medium) was determined as an in vitro method for predicting skin irritation. In addition, an MTT assay was used as a viability marker in keratinocytes NCTC 2544. Keratinocytes are a biologically relevant target for developing in vitro techniques to assess skin irritants: moreover, they are the principal source of the proinflammatory cytokine IL-1 alpha in the epidermis. Lysine derivatives proved to be less potent in stimulating IL-1 alpha synthesis and induced a lower release of this cytokine into the culture medium when compared to the anionic surfactant sodium dodecyl sulfate. Due to their low irritancy potential, lysine-based surfactants may offer promising applications in pharmaceutical and cosmetic preparations.

Serum levels of TNF-alpha, IFN-gamma, IL-6, IL-8, IL-12, IL-17, and IL-18 in patients with active psoriasis and correlation with disease severity

Recent progress in the understanding of psoriasis has shown that the regulation of local and systemic cytokines plays an important role in its pathogenesis. The most often used psoriasis score is the psoriasis area and severity index (PASI). A simple laboratory test from a blood sample would be an attractive, patient-independent, and observer-independent marker of disease severity. To this end, we evaluated the association of serum levels of some proinflammatory cytokines in vivo and their correlation with severity of psoriasis. The serum levels of cytokines levels were determined with the use of the ELISA method. All mean values except IL-17 levels of patients were significantly higher than those of controls. There was a significant correlation between serum levels of IFN-γ, IL-12, IL-17, and IL-18, and severity of the disease. Psoriasis can be described as a T-cell-mediated disease, with a complex role for a variety of cytokines, which has led to the development of new immunomodulatory therapies. In this study, serum TNF-α, IFN-γ, IL-6, IL-8, IL-12, and IL-18 levels were significantly higher in active psoriatic patients than in controls. Furthermore, high levels of IFN-γ, IL-12, and IL-18 correlated with the clinical severity and activity of psoriasis, and those measurements of serum levels of these cytokines may be objective parameters for the disease severity.

Stimulation of epidermal calcium gradient loss and increase in TNF-alpha and IL-1alpha expressions by glycolic acid in murine epidermis

In a previous study, we reported that alpha-hydroxy acids (AHA), such as glycolic acid and lactic acid, did not induce any significant changes in transepidermal water loss for normal murine skin. The ultrastructural observations, however, showed that the extent of lamellar body exocytosis significantly increased. Because AHA can theoretically decrease the calcium ion concentration by chelation, topical AHA may induce the loss of epidermal calcium gradient by lowering the calcium ion concentration in the granulocytes and, subsequently, induce lamellar body secretion. The aim of this study is to verify that glycolic acid could modulate the epidermal calcium gradient and increase lamellar body exocytosis. Seventy per cent of glycolic acid aqueous solution was applied to the normal skin of hairless mice and biochemical and morphological studies were performed. The loss of epidermal calcium gradient was observed in glycolic-acid-applied skin of hairless mice and subsequent barrier function recovery processes, such as an increase in lamellar body secretion, were observed. The extracellular glycolic acid was found to inhibit the change in intracellular calcium ion concentration in response to extracellular calcium ion concentration changes in the cultured mouse keratinocyte in vitro. The protein and mRNA expressions of tumour necrosis factor-alpha and interleukin-1alpha in the murine epidermis were significantly increased after glycolic acid application. An in vitro study using cultured keratinocytes suggested that glycolic acid could lower the calcium ion concentration, at least in part, through the chelating effects of the glycolic acid on the cationic ions.

Nadifloxacin, an antiacne quinolone antimicrobial, inhibits the production of proinflammatory cytokines by human peripheral blood mononuclear cells and normal human keratinocytes

BACKGROUND

Acne vulgaris is a chronic inflammatory disease involving colonization of Propionibacterium acnes (P. acnes), activation of neutrophils and lymphocytes. Circumstantial evidence suggests that antigen-independent and -dependent immune responses against P. acnes are involved in the pathogenesis of inflammatory acne. Epidermal keratinocytes are also suggested to be involved in initiation and progression of cutaneous inflammation. Nadifloxacin, a fluorinated quinolone, has potent antimicrobial activities against Gram-negative and -positive microbes and is used to treat multiple inflamed acne lesions. However, its effect on immune conferring cells such as mononuclear cells and keratinocytes has not been examined.

OBJECTIVE

To evaluate the possible involvement of potential anti-inflammatory activity of nadifloxacin in its therapeutic effect on inflammatory acne, we examined the effects of nadifloxacin, in comparison with other antibiotics used to treat acne vulgaris, on cytokine production by human peripheral blood mononuclear cells (PBMC) and keratinocytes.

METHODS

Cytokine production by PBMC was determined after treatment with heat-killed P. acnes in the presence or absence of antimicrobials using a real-time PCR and ELISA. Cultured human epidermal keratinocytes were stimulated by IFN-gamma plus IL-1beta and the effects of antimicrobials were examined by using ELISA.

RESULTS

Nadifloxacin as well as macrolide antibiotics and clindamycin inhibited IL-12 and IFN-gamma production by PBMC stimulated by heat-killed P. acnes. The drug also inhibited the IL-1alpha, Il-6, IL-8 and GM-CMS production by keratinocytes treated with IFN-gamma plus IL-1beta.

CONCLUSIONS

Inhibitory effects of nadifloxacin to activate T cells and keratinocytes may be involved at least in part in the mechanism of its therapeutic effect against inflammatory acne.

The role of interleukin 10 in the pathogenesis and potential treatment of skin diseases

Interleukin 10 (IL-10) is a key cytokine produced by a multitude of immune effector cells and possesses distinct regulatory effects on immune functioning in the skin. In this article we report the current understanding of the immunobiology of IL-10 and identify the role of IL-10 in cutaneous infection as well as in autoimmune and neoplastic processes. We reviewed the literature to examine the function of IL-10 in different cutaneous disorders. IL-10 can influence and potentially treat T1/T2 differentiation, antigen-presenting cell functioning, antigen-presenting cell-mediated T-cell activation, and T-cell, B-cell, and mast cell growth and differentiation that is aberrant in various disease processes. The literature consensus is that the multitude of effects of IL-10 contribute to the pathogenesis of different skin disorders. In certain circumstances IL-10 could represent novel therapeutic approaches to treating cutaneous diseases.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be acquainted with the role of IL-10 in many infectious diseases, autoimmune skin disease, inflammatory processes, and malignancy. Its possible role in the resolution of various skin diseases should be better understood.