Cytokines as therapeutic targets in skin inflammation

Cheungsam Seed Husk Extract Reduces Skin Inflammation through Regulation of Inflammatory Mediator in TNF-α/IFN-γ-Induced HaCaT Cells

Cannabis contains numerous natural components and has several effects such as anticancer, anti-inflammatory and antioxidant. Cheungsam is a variety of non-drug-type hemp, developed in Korea and is used for fiber (stem) and oil (seed). The efficacy of Cheungsam on skin is not yet known, and although there are previous studies on Cheungsam seed oil, there are no studies on Cheungsam seed husk. In this study, we investigated the potential of Cheungsam seed husk ethanol extract (CSSH) to alleviate skin inflammation through evaluating the gene and protein expression levels of inflammatory mediators. The results showed that CSSH reduced pro-inflammatory cytokines (IL-1β, IL-6, IL-8, MCP-1 and CXCL10) and atopic dermatitis-related cytokines (IL-4, CCL17, MDC and RANTES) in TNF-α/IFN-γ-induced HaCaT cells. Furthermore, ERK, JNK and p38 phosphorylation were decreased and p-p65, p-IκBα, NLRP3, caspase-1, p-JAK1 and p-STAT6 were suppressed after CSSH treatment. CSSH significantly increased the level of the skin barrier factors filaggrin and involucrin. These results suggest that Cheungsam seed husk ethanol extract regulates the mechanism of skin inflammation and can be used as a new treatment for skin inflammatory diseases.

The Association of Oleic Acid and Dexamethasone Acetate into Nanocapsules Enables a Reduction in the Effective Corticosteroid Dose in a UVB Radiation-Induced Sunburn Model in Mice

Dexamethasone has a high anti-inflammatory efficacy in treating skin inflammation. However, its use is related to the rebound effect, rosacea, purple, and increased blood glucose levels. Nanotechnology approaches have emerged as strategies for drug delivery due to their advantages in improving therapeutic effects. To reduce dexamethasone-related adverse effects and improve the anti-inflammatory efficacy of treatments, we developed nanocarriers containing this corticosteroid and oleic acid. Nanocapsules and nanoemulsion presented dexamethasone content close to the theoretical value and controlled dexamethasone release in an in vitro assay. Gellan gum-based hydrogels were successfully prepared to employ the nanostructured systems. A permeation study employing porcine skin showed that hydrogels containing non-nanoencapsulated dexamethasone (0.025%) plus oleic acid (3%) or oleic acid (3%) plus dexamethasone (0.025%)-loaded nanocapsules provided a higher amount of dexamethasone in the epidermis compared to non-nanoencapsulated dexamethasone (0.5%). Hydrogels containing oleic acid plus dexamethasone-loaded nanocapsules effectively inhibited mice ear edema (with inhibitions of 89.26 ± 3.77% and 85.11 ± 2.88%, respectively) and inflammatory cell infiltration (with inhibitions of 49.58 ± 4.29% and 27.60 ± 11.70%, respectively). Importantly, the dexamethasone dose employed in hydrogels containing the nanocapsules that effectively inhibited ear edema and cell infiltration was 20-fold lower (0.025%) than that of non-nanoencapsulated dexamethasone (0.5%). Additionally, no adverse effects were observed in preliminary toxicity tests. Our study suggests that nanostructured hydrogel containing a reduced effective dose of dexamethasone could be a promising therapeutic alternative to treat inflammatory disorders with reduced or absent adverse effects. Additionally, testing our formulation in a clinical study on patients with skin inflammatory diseases would be very important to validate our study.

N-Methyl-(2S,4R)-trans-4-hydroxy-L-proline isolated Sideroxylon obtusifolium attenuates TPA-induced irritant contact dermatitis in mice

Dermatitis is defined as a set of inflammatory diseases that affect the skin, with varied causes. Among the different types of dermatitis, contact dermatitis is the most prevalent. Although the current therapy is often effective, it is associated with adverse effects and the possibility of drug tolerance. N-Methyl-(2S, 4R)-trans-4-hydroxy-L-proline is a L-proline amino acid derivative found in the leaves of Sideroxylon obtusifolium, a species traditionally used to treat inflammatory diseases. The aim of this study was to investigate the topical anti-inflammatory effect of N-methyl-(2S, 4R)-trans-4-hydroxy-L-proline (NMP) in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced irritant contact dermatitis in mice. Topically administered NMP, at doses of 0.03 - 0.50 mg/ear, reduced TPA-induced ear edema and neutrophil migration, as evidenced by low tissue myeloperoxidase activity and verified by histological examination. In addition, NMP (0.06 mg/ear) reduced tissue levels of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β, INF-γ and MCP-1) and of the anti-inflammatory cytokine IL-10, and reduced gene expression of TNF-α, IL-6 and IL-1β increased by TPA. The data suggest that N-methyl-(2S, 4R)-trans-4-hydroxy-L-proline acts as a topical anti-inflammatory agent that decreases the expression of inflammatory cytokines, making it useful for the treatment of skin inflammation. Further investigations are necessary for its development as a therapeutic agent.

An Overview of Nanoemulgels for Bioavailability Enhancement in Inflammatory Conditions via Topical Delivery

The anti-inflammatory drugs that are generally available possess the disadvantage of hydrophobicity, which leads to poor permeability and erratic bioavailability. Nanoemulgels (NEGs) are novel drug delivery systems that aim to improve the solubility and permeability of drugs across the biological membrane. The nano-sized droplets in the nanoemulsion enhance the permeation of the formulation, along with surfactants and co-surfactants that act as permeation enhancers and can further improve permeability. The hydrogel component of NEG helps to increase the viscosity and spreadability of the formulation, making it ideal for topical application. Moreover, oils that have anti-inflammatory properties, such as eucalyptus oil, emu oil and clove oil, are used as oil phases in the preparation of the nanoemulsion, which shows a synergistic effect with active moiety and enhances its overall therapeutic profile. This leads to the creation of hydrophobic drugs that possess enhanced pharmacokinetic and pharmacodynamic properties, and simultaneously avoid systemic side effects in individuals with external inflammatory disorders. The nanoemulsion's effective spreadability, ease of application, non-invasive administration, and subsequent ability to achieve patient compliance make it more suitable for topical application in the combat of many inflammatory disorders, such as dermatitis, psoriasis, rheumatoid arthritis, osteoarthritis and so on. Although the large-scale practical application of NEG is limited due to problems regarding its scalability and thermodynamic instability, which arise from the use of high-energy approaches during the production of the nanoemulsion, these can be resolved by the advancement of an alternative nanoemulsification technique. Considering the potential advantages and long-term benefits of NEGs, the authors of this paper have compiled a review that elaborates the potential significance of utilizing nanoemulgels in a topical delivery system for anti-inflammatory drugs.

Single-cell profiles reveal distinctive immune response in atopic dermatitis in contrast to psoriasis

BACKGROUND

Understanding the complex orchestrated inflammation in atopic dermatitis (AD), one of the most common chronic inflammatory diseases worldwide, is essential for therapeutic approaches. However, a comparative analysis on the single-cell level of the inflammation signatures correlated with the severity is missing so far.

METHODS

We applied single-cell RNA and T-cell receptor (TCR) sequencing on immune cells enriched from skin biopsies and matched blood samples of AD in comparison with psoriasis (PS) patients.

RESULTS

Clonally propagated skin-derived T cells showed disease-specific TCR motifs shared between patients which was more pronounced in PS compared to AD. The disease-specific T-cell clusters were mostly of a Th2/Th22 sub-population in AD and Th17/Tc17 in PS, and their numbers were associated with severity scores in both diseases. Herein, we provide for the first time a list that associates cell type-specific gene expression with the severity of the two most common chronic inflammatory skin diseases. Investigating the cell signatures in the patients´ PBMCs and skin stromal cells, a systemic involvement of type-3 inflammation was clearly detectable in PS circulating cells, while in AD inflammatory signatures were most pronounced in fibroblasts, pericytes, and keratinocytes. Compositional and functional analyses of myeloid cells revealed the activation of antiviral responses in macrophages in association with disease severity in both diseases.

CONCLUSION

Different disease-driving cell types and subtypes which contribute to the hallmarks of type-2 and type-3 inflammatory signatures and are associated with disease activities could be identified by single-cell RNA-seq and TCR-seq in AD and PS.

Eczema is a shared risk factor for anxiety and depression: A meta-analysis and systematic review

Globally, anxiety and depression are the most common psychiatric disorders that add large burdens to individuals and society; however, the mechanisms underlying these disorders are unclear. Several studies have found that eczema is a shared risk factor for both these conditions. We identified and evaluated eligible observational studies from EMBASE and PubMed. In total, 20 relevant cohort and case-control studies comprising 141,910 patients with eczema and 4,736,222 control participants fulfilled our established criteria. Information extracted included study design, location, sample size, sex distribution of cases and controls or reference cohorts, measurements of outcomes, odds ratio (OR) with 95% confidence interval (CI), and adjusted factors for exposure associated with outcome risk. The meta-analysis was performed by calculating the pooled OR with 95% CI, and heterogeneity was assessed using Cochrane Q and I2 statistics. The pooled effect showed a positive association (n = 4,896,099, OR = 1.63, 95% CI [1.42-1.88], p<0.001) between eczema and depression or anxiety, with positive associations also observed in the depression (n = 4,878,746, OR = 1.64, 95% CI [1.39-1.94], p<0.001) and anxiety (n = 4,607,597, OR = 1.68, 95% CI [1.27-2.21], p<0.001) groups. Subgroup and sensitivity analyses confirmed that these findings were stable and reliable. This study suggests that eczema is associated with an increased risk of developing depression and anxiety, which may assist clinicians in the prevention or treatment of these disorders.

Skin Immunosenescence and Type 2 Inflammation: A Mini-Review With an Inflammaging Perspective

Skin-resident stromal cells, including keratinocytes, fibroblasts, adipocytes, and immune cells including Langerhans cells, dendritic cells, T cells, and innate lymphoid cells, and their functional products work in concert to ensure the realization of skin barrier immunity. However, aging-induced immunosenescence predisposes the elderly to pruritic dermatoses, including type 2 inflammation-mediated. Inflammaging, characterized by chronic low level of pro-inflammatory cytokines released from senescent cells with the senescence-associated secretory phenotype (SASP), may drive immunosenescence and tangle with type 2 inflammatory dermatoses. The present mini-review summarizes current evidence on immunosenescence and type 2 inflammation in the skin and further focuses on future needs from an inflammaging perspective to clarify their complexity.

Effect of 1-MHz ultrasound on the proinflammatory interleukin-6 secretion in human keratinocytes

Keratinocytes, the main cell type of the skin, are one of the most exposed cells to environmental factors, providing a first defence barrier for the host and actively participating in immune response. In fact, keratinocytes express pattern recognition receptors that interact with pathogen associated molecular patterns and damage associated molecular patterns, leading to the production of cytokines and chemokines, including interleukin (IL)-6. Herein, we investigated whether mechanical energy transported by low intensity ultrasound (US) could generate a mechanical stress able to induce the release of inflammatory cytokine such IL-6 in the human keratinocyte cell line, HaCaT. The extensive clinical application of US in both diagnosis and therapy suggests the need to better understand the related biological effects. Our results point out that US promotes the overexpression and secretion of IL-6, associated with the activation of nuclear factor-κB (NF-κB). Furthermore, we observed a reduced cell viability dependent on exposure parameters together with alterations in membrane permeability, paving the way for further investigating the molecular mechanisms related to US exposure.

Tagitinin F has anti-inflammatory, anti-nociceptive and anti-matrix metalloproteinase properties: An in silico, in vitro and in vivo study

Sesquiterpene lactones (SL) are natural bioactive molecules indicated as potential scaffolds for anti-inflammatory and analgesic drug design. However, their anti-inflammatory applicability remains underestimated since the impact of SL on inflammatory nociception and tissue repair are overlooked. Thus, we used an integrated in silico, in vitro and in vivo framework to investigate the impact of tagitinin F (TAG-F) on lipopolysaccharide (LPS)-challenged macrophages, excisional skin wounds, and carrageenan-induced paw edema and mechanical hyperalgesia in mice. RAW 264.7 macrophages in culture were challenged with LPS and treated with TAG-F (5, 10, 50 and 100 μM). The paw of BALB/c mice was injected with carrageenan and treated with 0.5% and 1% TAG-F. Excisional wounds were also produced in BALB/c mice and treated with 0.5% and 1% TAG-F. Our results indicated a consistent concentration-dependent downregulation in 5-lipoxygenase, cyclooxygenase 1 and 2 (COX-1 and COX-2), matrix metalloproteinase 1 and 2 (MMP-1 and MMP-2) activities; as well as attenuation in prostaglandin E2 (PGE2), leukotriene B4 (LTB4) and tumor necrosis factor-α (TNF-α) production in both in vitro and in vivo models. In vivo, TAG-F also attenuated carrageenan-induced paw edema and mechanical hyperalgesia in mice. From the excisional skin wound, TAG-F was still effective in reducing neutrophils and macrophages infiltration and stimulating collagen deposition in the scar tissue, accelerating tissue maturation. Together, our findings indicate that the anti-inflammatory effect of TAG-F is more comprehensive than previously suggested, exerting a significant impact on the control of edema, inflammatory pain and modulating central metabolic processes linked to skin wound healing.

Skin immunity and its dysregulation in atopic dermatitis, hidradenitis suppurativa and vitiligo

While the epidermis is the frontline defense against infections and indeed, it is a peripheral lymphoid organ, the same immunological mechanisms may initiate and sustain pathological conditions. Indeed, a deregulated action against exogenous pathogens could activate a T cell response in atopic dermatitis, hidradenitis suppurativa and vitiligo. Atopic dermatitis (AD) is a chronic inflammatory skin condition with a complex pathophysiology. Although T helper 2 immunity dysregulation is thought to be the main cause of AD etiopathogenesis, the triggering mechanism is not well understood, and the treatment is often difficult. As the AD, hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a dramatic impact on the quality of life of the affected patients. The exact pathophysiology of HS is still unclear, but many evidences report a follicular obstruction and subsequent inflammation with TNF-α, interleukin (IL)-1β, IL-10, and IL-17 involvement. Vitiligo is an autoimmune epidermal disorder which consists of melanocytes destruction and skin depigmentation. Melanocytes destruction is mainly due to their increased oxidative-stress sensitivity with a consequent activation of innate first and adaptative immunity (CD8⁺ T cells) later. The understanding of the triggering mechanisms of AD, HS and Vitiligo is pivotal to outline novel therapies aimed at regaining the physiological immune homeostasis of healthy skin. The aim of this review is to provide new insight on the pathogenesis of these skin diseases and to highlight on the new therapeutic approaches adopted in the treatment of AD, HS and Vitiligo.

Alnus Sibirica Extracts Suppress the Expression of Inflammatory Cytokines Induced by Lipopolysaccharides, Tumor Necrosis Factor-α, and Interferon-γ in Human Dermal Fibroblasts

The effects of Alnus sibirica (AS) extracts on cytokine expression induced by inflammatory stimulants were examined in human dermal fibroblasts (HDFs) and RAW264.7 cells. The anti-oxidative effect and effect on cell viability of AS extracts were evaluated, and four extracts with the highest anti-oxidative effects were selected. HDFs and RAW264.7 cells were treated with inflammatory stimulants, and the expression of cytokines involved in acute (IL-6 and IL-10) and chronic (IL-18) inflammation, the initiation of the immune response (IL-33), and non-specific immune responses (IL-1β, IL-8, and TNF-α) were determined using a reverse-transcription polymerase chain reaction. LPS increased the expression of all the cytokines, except for IL-18; however, AS extracts, particularly AS2 and AS4, reduced this increase, and TNF-α treatment markedly increased the expression of cytokines related to non-specific immune responses. IFN-γ treatment induced no significant changes, except for increased IL-33 expression in HDFs. AS extracts inhibited the increase in the expression of IL-33 and other cytokines in HDFs. Thus, the exposure of HDFs and RAW264.7 cells to inflammatory stimulants increased the expression of cytokines related to all the inflammatory processes. HDFs are involved not only in simple tissue regeneration but also in inflammatory reactions in the skin. AS2 and AS4 may offer effective therapy for related conditions.

Control of cell death-associated danger signals during cornification prevents autoinflammation of the skin

The function of the skin as a barrier to the environment is mainly achieved by the outermost layers of the epidermis. In the granular layer, epidermal keratinocytes undergo the last steps of their terminal differentiation program resulting in cornification. The coordinated conversion of living keratinocytes into corneocytes, the building blocks of the cornified layer, represents a unique form of programmed cell death. Recent studies have identified numerous genes that are specifically expressed in terminally differentiated keratinocytes and, surprisingly, this genetic program does not only include mediators of cornification but also suppressors of pyroptosis, another mode of programmed cell death. Pyroptosis is activated by inflammasomes, leads to the release of interleukin-1 (IL-1) family cytokines, and thereby activates inflammation. In addition, inhibitors of potentially pro-inflammatory proteases and enzymes removing danger-associated cytoplasmic DNA are expressed in differentiated keratinocytes. We propose the concept of cornification as an inherently hazardous process in which damaging side effects are actively suppressed by protective mechanisms. In support of this hypothesis, loss-of-function mutations in epidermal protease inhibitors and IL-1 family antagonists suffice to induce autoinflammation. Similarly, exogenous disturbances of either cornification or its accompanying control mechanisms may be starting points for skin inflammation. Further studies into the relationship between cornification, pyroptosis and other forms of cell death will help to define the initiation phase of inflammatory skin diseases and offer new targets for disease prevention and therapy.

Chemical composition, antioxidant and anti-inflammatory activities of the essential oils from male and female specimens of Baccharis punctulata (Asteraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Baccharis punctulata (Asteraceae), popularly known as "Chíllka saru saru" in Bolivia, has been used by rural communities in Bustillo Province of the Potosi Department for treatment of asthma, luxations and contusions.

AIM OF THE STUDY

To analyze the chemical composition of the essential oils obtained from leaves of female (BPF) and male (BPM) specimens and evaluate their anti-inflammatory and antioxidant properties.

MATERIAL AND METHODS

Chemical composition analyses of Baccharis punctulata essential oils isolated by hidrodistillation from leaves of male and female specimens were performed by GC-FID-MS. The in vivo anti-inflammatory activity was evaluated using the model of TPA (12-O-tetradecanoylphorbol-13-acetate) induced ear edema, and the polymorphonuclear cell migration was evaluated by mieloperoxidase (MPO) and analyzed histologically. To measure the reactive oxygen species (ROS) in the inflamed tissue, the DCFH-DA fluorescent probe was used. The chemical in vitro antioxidant activity of essential oils was determined using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical assay.

RESULTS

The chemical analysis showed high proportion of sesquiterpenes in the volatiles samples obtained from BPM, such as δ-elemene (14.29%), germacrene D (11.29%) and bicyclogermacrene (10.90%), and in the sample from BPF, bicyclogermacrene (42.44%), germacrene D (21.18%) and β-caryophyllene (14.06%). A statistical difference (p < 0.05) on chemical composition between both essential oils was observed. Topical administration of both BPM and BPF essential oils was able to inhibit the formation of TPA-induced edema in the treated groups. Isolated administration of TPA promoted an increase in MPO enzyme activity, and inhibition of the increase of MPO activity was observed when animals were treated with BFP at concentrations of 0.1 mg/ear (13.69 ± 0.20%), 0.3 mg/ear (22.35 ± 0.11%), and 1.0 mg/ear (44.98 ± 0.27%). Topical treatment with BPM was able to inhibit MPO activity at 22.40 ± 0.29% (0.1 mg/ear), 36.49 ± 0.07% (0.3 mg/ear) and 52.19 ± 0.28% (1.0 mg/ear). The positive control of dexamethasone (DEXA, 0.1 mg/ear) was able to revert the increase in the enzymatic activity of MPO caused by TPA (65.16%). Histological analysis showed that topical application of TPA promoted intense cellular infiltration. This inflammatory parameter was reduced with the topical application of the BPF and BPM oil samples as well as with DEXA. The results observed in the ROS and DPPH tests suggest that both samples were able to reduce the inflammatory cells influx and have in vitro antioxidant properties, respectively.

CONCLUSIONS

This study presents, for the first time, the chemical composition of the essential oils obtained from leaves of male and female specimens of Baccharis punctulata, and their anti-inflammatory and antioxidant activities. The results presented by the volatile samples in our biotests support traditional uses of this plant species.

Nanoemulsion strategy of pioglitazone for the treatment of skin inflammatory diseases

Pioglitazone (PGZ) is a peroxisome proliferator-activated receptor agonist. Its role in the inflammatory response modulation paves the way for additional therapeutic applications. The purpose of this study was to develop a pioglitazone nanoemulsion (PGZ-NE) in order to investigate its anti-inflammatory efficacy on the skin. To that end, an NE vehicle developed for skin delivery was optimized and characterized. The resulting PGZ-NE showed good anti-inflammatory efficacy by decreasing the expression of inflammatory cytokines IL-6, IL-1β and TNF-α. The properties of the developed nanocarrier allowed achievement of a high permeation flux of PGZ through the skin as well as a high retained amount in the skin, likely due to the depot effect of ingredients, which assured a prolonged local action, with good skin tolerability among participating individuals. Consequently, these results suggest that PGZ-NE may be used as an alternative treatment for inflammatory skin diseases such as rosacea, atopic dermatitis or psoriasis.

Inflammatory mediators causing cutaneous chronic itch in some diseases via transient receptor potential channel subfamily V member 1 and subfamily A member 1

Chronic itch with an itch-scratch vicious circle is a significant problem in a large amount of diseases. Some of these diseases, such as psoriasis, atopic dermatitis, prurigo nodularis, Sézary syndrome, uremic pruritus, diabetes and jaundice, are common. For a very long time, chronic itch has been a thorny problem with few effective treatments. Because of this, itch researchers and dermatologists seek to find the mechanisms among chronic itch, inflammatory cytokines and neurons. As an immediate area of research focus, we are going to find the peripheral cross-talk between neurons and skin cells. Two receptors, named transient receptor potential channel vanilloid 1 and transient receptor potential channel ankyrin transmembrane protein 1, have been shown to play important roles in chronic itch. Many advances have been made so far this decade. This review talks about the updated mechanism of itch-related inflammatory cytokines via transient receptor potential channels in cutaneous chronic itch and corresponding diseases. The search for itch-related inflammatory mediators and the structure of transient receptor potential channels this decade could deepen our understanding of the mechanism of itch and help us find more treatments of chronic itch in the future.

Nasturtium officinale R. Br. effectively reduces the skin inflammation induced by croton oil via glucocorticoid receptor-dependent and NF-κB pathways without causing toxicological effects in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammatory skin diseases treatments currently used cause adverse effects. Nasturtium officinale (watercress) is used popularly as an anti-inflammatory. However, until now, no study proved its effectiveness as a topical treatment to inflammatory skin diseases. The topical anti-inflammatory activity of N. officinale crude extract leaves (NoE) on an irritant contact dermatitis (ICD) model croton oil-induced in mice was investigated.

MATERIALS AND METHODS

ICD models were induced by a single (1 mg/ear; acute) or repeated (0.4 mg/ear; chronic; 9 days total) croton oil application. NoE and dexamethasone solutions' (diluted in acetone; 20 μL/ear) or NoE gel, dexamethasone gel and base gel (15 mg/ear) were topically applied immediately after croton oil application. The NoE topical anti-inflammatory effect was evaluated for inflammatory parameters (ear edema, inflammatory cells infiltration, and inflammatory cytokines levels). NoE topical anti-inflammatory mechanism (NF-κB pathway and effect glucocorticoid-like) were assessed by western blot and ear edema analyses, respectively. UHPLC-MS/MS chromatography, gels accelerated stability and preliminary study of adverse effects was also performed.

RESULTS

UHPLC-MS/MS of the NoE revealed the presence of coumaric acid, rutin, and ferulic acid. NoE gels stability study showed no relevant changes at low temperature. NoE, dexamethasone, NoE gel and dexamethasone gel inhibited the ear edema croton oil-induced by 82 ± 6% (1 mg/ear), 99 ± 1% (0.1 mg/ear), 81 ± 8% (3%) and 70 ± 6% (0.5%) for the acute model, and 49 ± 7% (1 mg/ear), 80 ± 4% (0.1 mg/ear), 41 ± 8% (3%) and 46 ± 14% (0.5%) for the chronic model, respectively. The same treatments also reduced the inflammatory cells infiltration by 62 ± 3% (1 mg/ear), 97 ± 2% (0.1 mg/ear), 60 ± 3% (3%) and 66 ± 6% (0.5%) for the acute model, respectively, and 25 ± 8% (1 mg/ear) to NoE and 83 ± 13% to dexamethasone to the chronic model. NoE and NoE gel reduced the pro-inflammatory cytokines levels (acute ICD model) by 62 ± 5% and 71 ± 3% (MIP-2) and 32 ± 3% and 44 ± 4% (IL-1β), while dexamethasone solution's and gel reduced by 79 ± 7% and 44 ± 4% to MIP-2 and 98 ± 2% and 83 ± 9% to IL-1β, respectively. NoE' and dexamethasone' solutions inhibited the reduction of IkB-α protein expression induced by croton oil by 100% and 80 ± 14%, respectively. Besides, the mifepristone (glucocorticoid receptor antagonist) pre-treatment prevented the topical anti-edematogenic effect of NoE' and dexamethasone' solutions by 61 ± 5% to NoE and 78 ± 16% to dexamethasone. The repeated topical application of NoE did not cause adverse effects.

CONCLUSION

Our results suggest the N. officinale use in the cutaneous inflammatory process treatment and demonstrate the NoE potential to develop a promising topical anti-inflammatory agent to treat inflammatory disorders.

Anti-inflammatory effect of external use of escin on cutaneous inflammation: possible involvement of glucocorticoids receptor

Escin, as an internally applied anti-inflammatory agent, has been widely used in the treatment of inflammation and edema resulting from trauma or operation in the clinic. However, the effect of its external use on cutaneous inflammation and edema remains unexplored. In the present study, the anti-inflammatory and anti-edematous effects of external use of escin were studied in carrageenan-induced paw edema and histamine-induced capillary permeability in rats, paraxylene-induced ear swelling in mice, and cotton pellet-induced granuloma in rats. Effects of external use of escin gel on prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were determined by ELISA. The anti-inflammatory mechanism was explored by detecting the expression of glucocorticoid receptor (GR) with Western blotting and Real-time PCR analyses, with further exploration of nuclear factor-κB (NF-κB), p38 mitogen-activated protein kinase (P38MAPK) and activator protein-1 (AP-1) expressions. We demonstrated that external use of escin showed significant anti-inflammatory effects on acute and chronic inflammation in different animal models and its anti-inflammatory effects might be related to down-regulation of PGE2, TNF-α, and IL-1β. The results also showed that escin exerted its anti-inflammatory effects by promoting the expression of GR, with the possible mechanism being inhibition of the expressions of GR-related signaling molecules such as NF-κB and AP-1.

Toward Immunocompetent 3D Skin Models

3D human skin models provide a platform for toxicity testing, biomaterials evaluation, and investigation of fundamental biological processes. However, the majority of current in vitro models lack an inflammatory system, vasculature, and other characteristics of native skin, indicating scope for more physiologically complex models. Looking at the immune system, there are a variety of cells that could be integrated to create novel skin models, but to do this effectively it is also necessary to understand the interface between skin biology and tissue engineering as well as the different roles the immune system plays in specific health and disease states. Here, a progress report on skin immunity and current immunocompetent skin models with a focus on construction methods is presented; scaffold and cell choice as well as the requirements of physiologically relevant models are elaborated. The wide range of technological and fundamental challenges that need to be addressed to successfully generate immunocompetent skin models and the steps currently being made globally by researchers as they develop new models are explored. Induced pluripotent stem cells, microfluidic platforms to control the model environment, and new real-time monitoring techniques capable of probing biochemical processes within the models are discussed.

The ARE-binding protein Tristetraprolin (TTP) is a novel target and mediator of calcineurin tumor suppressing function in the skin

An increased incidence of skin inflammatory diseases is frequently observed in organtransplanted patients being treated with calcineurin inhibitor-based immunosuppressive agents. The mechanism of increased skin inflammation in this context has however not yet been clarified. Here we report an increased inflammation following inhibition of calcineurin signaling seen in both chemically induced mouse skin tumors and in tumors grafted from H-rasV12 expressing primary human keratinocytes (HKCs). Following UVB or TPA treatment, we specifically found that deletion of the calcineurin gene in mouse keratinocytes (MKCs) resulted in increased inflammation, and this was accompanied by the enhanced production of pro-inflammatory cytokines, such as TNFα, IL-8 and CXCL1. Furthermore, expression of the RNA-binding protein, tristetraprolin (TTP) was down-regulated in response to calcineurin inhibition, wherein TTP was shown to negatively regulate the production of pro-inflammatory cytokines in keratinocytes. The induction of TTP following TPA or UVB treatment was attenuated by calcineurin inhibition in keratinocytes, and correspondingly, disruption of calcineurin signaling down-regulated the amounts of TTP in both clinical and H-rasV12-transformed keratinocyte tumor models. Our results further demonstrated that calcineurin positively controls the stabilization of TTP in keratinocytes through a proteasome-dependent mechanism. Reducing the expression of TTP functionally promoted tumor growth of H-rasV12 expressing HKCs, while stabilizing TTP expression counteracted the tumor-promoting effects of calcineurin inhibition. Collectively these results suggest that calcineurin signaling, acting through TTP protein level stabilization, suppresses keratinocyte tumors by downregulating skin inflammation.

Inflammatory and Noninflammatory Itch: Implications in Pathophysiology-Directed Treatments

Itch is the main chief complaint in patients visiting dermatologic clinics and has the ability to deeply impair life quality. Itch results from activation of cutaneous nerve endings by noxious stimuli such as inflammatory mediators, neurotransmitters and neuropeptides, causing itch signal transduction from peripheral skin, through the spinal cord and thalamus, to the brain cortex. Primarily noninflammatory diseases, such as uremic pruritus, cause itch through certain pruritogens in the skin. In inflammatory skin diseases, atopic dermatitis (AD) is the prototypic disease causing intensive itch by aberrant skin inflammation and epidermal barrier disruption. Recent understanding of disease susceptibility, severity markers, and mechanisms have helped to develop targeted therapy for itch in AD, including monoclonal antibodies against IL-4, IL-13, thymic stromal lymphopoietin (TSLP), IgE and IL-31. Promising effects have been observed in some of them. In this review, we summarized targeted therapies for inflammatory itch in AD and for managing abnormal itch transductions in other common itching skin diseases.

The caspase-1 inhibitor CARD18 is specifically expressed during late differentiation of keratinocytes and its expression is lost in lichen planus

BACKGROUND

CARD18 contains a caspase recruitment domain (CARD) via which it binds to caspase-1 and thereby inhibits caspase-1-mediated activation of the pro-inflammatory cytokine interleukin (IL)-1β.

OBJECTIVES

To determine the expression profile and the role of CARD18 during differentiation of keratinocytes and to compare the expression of CARD18 in normal skin and in inflammatory skin diseases.

METHODS

Human keratinocytes were induced to differentiate in monolayer and in 3D skin equivalent cultures. In some experiments, CARD18-specific siRNAs were used to knock down expression of CARD18. CARD18 mRNA levels were determined by quantitative real-time PCR, and CARD18 protein was detected by Western blot and immunofluorescence analyses. In situ expression was analyzed in skin biopsies obtained from healthy donors and patients with psoriasis and lichen planus.

RESULTS

CARD18 mRNA was expressed in the epidermis at more than 100-fold higher levels than in any other human tissue. Within the epidermis, CARD18 was specifically expressed in the granular layer. In vitro CARD18 was strongly upregulated at both mRNA and protein levels in keratinocytes undergoing terminal differentiation. In skin equivalent cultures the expression of CARD18 was efficiently suppressed by siRNAs without impairing stratum corneum formation. Epidermal expression of CARD18 was increased after ultraviolet (UV)B irradiation of skin explants. In skin biopsies of patients with psoriasis no consistent regulation of CARD18 expression was observed, however, in lesional epidermis of patients with lichen planus, CARD18 expression was either greatly diminished or entirely absent whereas in non-lesional areas expression was comparable to normal skin.

CONCLUSIONS

Our results identify CARD18 as a differentiation-associated keratinocyte protein that is altered in abundance by UV stress. Its downregulation in lichen planus indicates a potential role in inflammatory reactions of the epidermis in this disease.

AP-1 Expression and its Clinical Relevance in Immune Disorders and Cancer

The inflammatory response is known to have a significant role in certain autoimmune diseases and malignancies. We review current knowledge regarding the functions of activator protein 1 (AP-1) as an important modulator in several immune disorders and carcinomas. AP-1 is overexpressed in rheumatoid arthritis and in long-term allogeneic hematopoietic stem cell transplantation survivors; however, decreased expression of AP-1 has been observed in psoriasis, systematic lupus erythematosus and in patients who do not survive after hematopoietic stem cell transplantation. AP-1 also is implicated in the control of various cancer cells. Higher levels of AP-1 components are present in breast and endometrial carcinomas, colorectal cancer and in acute myeloid leukemia, Hodgkin׳s lymphoma and anaplastic large cell lymphoma, with downregulation in ovarian and gastric carcinomas and in patients with chronic myelogenous leukemia. AP-1 may enable the development of helpful markers to identify early-stage disease or to predict severity.

Hydroalcoholic extract of Sapium glandulatum (Vell.) Pax displays potent anti-inflammatory activities through a glucocorticoid receptor-dependent pathway

BACKGROUND

Ethnobotanical studies of the Sapium genus reveal that many species are widely used in several countries as therapeutic drugs and they are widely used in folk medicine for treatment of different diseases, including skin inflammation. This raises interest in the study of the pharmacological properties and phytochemical composition of these plants. The biological properties of Sapium glandulatum, a native species of southern Brazil, has not been reported in the literature.

PURPOSE

The aim of the present study was to investigate the anti-inflammatory action of the hydroalcoholic extract of Sapium glandulatum (EHSG) leaves in mouse models of acute or chronic skin inflammation.

STUDY DESIGN/METHODS

Topical effects of EHSG were evaluated in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema in the ear. Systemic effects of the extract were studied in a TPA-induced ear edema model, as well as in a carrageenan-induced paw edema model. To gain insight into the mechanism by which EHSG blocked inflammation, we evaluated the role of glucocorticoid receptors (GR) using the TPA-induced ear edema model and also measured specific binding in a glucocorticoid assay. Possible adverse effects of EHSG were evaluated after multiple treatments with the extract in the skin atrophy model on the ear and with the alkaline comet assay.

RESULTS

EHSG presented potent anti-inflammatory activity when applied topically in acute and chronic models, inhibiting edema formation and leukocyte migration as well as expression pro-inflammatory cytokines IL-1β, IL-6 and TNF-α in the tissue. Similar anti-inflammatory effects were found following oral treatment in both ear and paw edema models. Strikingly, the EHSG-induced blockade of leukocyte migration was reversed by mifepristone, a GR antagonist. Additionally, a specific binding assay revealed that ESGH interacts with GR. Multiple treatments with EHSG failed to induce adverse effects when evaluated in the skin atrophy model and bone marrow genotoxicity test.

CONCLUSION

Taken together, our data suggest that EHSG is a potential source of anti-inflammatory tool compounds for the treatment of pro-inflammatory-derived skin diseases, and its mechanism of action may be, at least in part, via the GR pathway.