Mouse Model Of Skin Inflammation Research Articles

157 IL-10+ regulatory B cell migration into inflamed skin limits cutaneous inflammation

To maintain skin homeostasis several types of leukocytes exist in or are recruited into the skin. While most of these leukocytes are well characterized, the roles of skin-associated B cells remain largely unknown. Our lab previously demonstrated that a subset of IL-10+ regulatory B cells preferentially migrates into the inflamed skin of mice, a process that required α4β1 integrin. Thus, we hypothesized that B regulatory cells suppress skin inflammation and that impaired migration of these cells into the skin exacerbates skin inflammation. To test this hypothesis, we used two mouse models of skin inflammation: (i) IL-17-dominated psoriasiform skin inflammation induced by imiquimod (IMQ) cream and (ii) IFN-γ-mediated cutaneous delayed contact hypersensitivity elicited by dinitrofluorobenzene (DNFB). Furthermore, we employed a mouse model with a B cell-specific tamoxifen-inducible deletion of α4-integrin (Itga4). Here, we found that inducing the deletion of Itga4 in B cells led to a significant decreased in skin-associated IL-10+ B cells in inflamed skin and included both conventional B2 (CD19+B220highCD43-) and innate-like B1 (CD19+B220-/lowCD43+) cells. The decrease accumulation of IL-10+ regulatory B cells was associated with a significant increase in the clinical and histopathological parameters of skin inflammation in both skin inflammation models. Thus, our data show a crucial function of skin-homing IL-10+ regulatory B cells in the suppression of IL-17- and IFN-γ-dominated skin inflammation; supporting the notion that B regulatory cells are critical players in the cutaneous environment during inflammatory skin diseases.

Inflammatory Skin-Derived Cytokines Accelerate Osteoporosis in Mice with Persistent Skin Inflammation.

Secondary osteoporosis can also be caused by chronic inflammatory skin disease as well as rheumatoid arthritis or inflammatory bowel disease. However, the exact role of osteoporosis in inflammatory skin conditions has not been elucidated. Using a mouse model of dermatitis, we investigated the pathophysiology of osteoporosis in inflammatory skin conditions and the therapeutic impact of osteoporosis medication on inflammatory skin disease. We employed model mice of spontaneous skin inflammation, specifically overexpressing human caspase-1 in the epidermis. Bone density and the expression of various mRNAs in the femur were examined by micro CT and RT-PCR. The effects of minodronate and anti-RANKL antibody on bone structure, histology, and femur blood flow were studied. The mouse model of skin inflammation showed a marked decrease in bone density compared to wild-type littermates with abnormalities in both bone resorption and formation. Minodronate improved bone density by decreasing osteoclasts, but anti-RANKL antibody did not improve. In the dermatitis model, the blood flow in the bone marrow was decreased, and minodronate restored this parameter. A model of persistent dermatitis exhibited marked osteoporosis, but the impact of chronic dermatitis on osteoporosis has not been thoroughly investigated. We should explore the pathogenesis of osteoporosis in skin inflammatory diseases.

Successful Regulatory T Cell-Based Therapy Relies on Inhibition of T Cell Effector Function and Enrichment of FOXP3+ Cells in a Humanized Mouse Model of Skin Inflammation.

Background Recent clinical trials using regulatory T cells (Treg) support the therapeutic potential of Treg-based therapy in transplantation and autoinflammatory diseases. Despite these clinical successes, the effect of Treg on inflamed tissues, as well as their impact on immune effector function in vivo, is poorly understood. Therefore, we here evaluated the effect of human Treg injection on cutaneous inflammatory processes in vivo using a humanized mouse model of human skin inflammation (huPBL-SCID-huSkin). Methods SCID beige mice were transplanted with human skin followed by intraperitoneal (IP) injection of 20‐40 × 106 allogeneic human PBMCs. This typically results in human skin inflammation as indicated by epidermal thickening (hyperkeratosis) and changes in dermal inflammatory markers such as the antimicrobial peptide hBD2 and epidermal barrier cytokeratins K10 and K16, as well as T cell infiltration in the dermis. Ex vivo-expanded human Treg were infused intraperitoneally. Human cutaneous inflammation and systemic immune responses were analysed by immunohistochemistry and flow cytometry. Results We confirmed that human Treg injection inhibits skin inflammation and the influx of effector T cells. As a novel finding, we demonstrate that human Treg injection led to a reduction of IL-17-secreting cells while promoting a relative increase in immunosuppressive FOXP3+ Treg in the human skin, indicating active immune regulation in controlling the local proinflammatory response. Consistent with the local control (skin), systemically (splenocytes), we observed that Treg injection led to lower frequencies of IFNγ and IL-17A-expressing human T cells, while a trend towards enrichment of FOXP3+ Treg was observed. Conclusion Taken together, we demonstrate that inhibition of skin inflammation by Treg infusion, next to a reduction of infiltrating effector T cells, is mediated by restoring both the local and systemic balance between cytokine-producing effector T cells and immunoregulatory T cells. This work furthers our understanding of Treg-based immunotherapy.

γ分泌酶抑制剂阻断Notch-Hes1信号通路对银屑病样皮炎小鼠γδT17细胞表达的影响

Objective To evaluate the effect of Notch-Hes1 signaling blockade by a γ-secretase inhibitor on the expression of γδT17 cells in a mouse model of psoriasis-like skin inflammation. Methods Forty-five healthy specific pathogen-free (SPF) male BALB/c mice were randomly divided into control group, model group and intervention group by simple random sampling. The model group and intervention group were both topically treated with imiquimod 5% cream (62.5 mg once a day) on the shaved back, the intervention group were then intraperitoneally injected with the γ-secretase inhibitor DAPT (10 mg/kg once a day) immediately after topical application of imiquimod, and the control group were topically treated with equivalent amount of vaseline once a day. After 6-day treatment, psoriasis area and severity index (PASI) was used to evaluate changes of skin lesions. On day 7, blood samples were obtained from all the mice through heart puncture after anesthetization, and spleen and skin tissues were acquired to prepare single cell suspension. Spleen index was compared among the 3 groups. Skin tissues on the mouse back were resected and subjected to hematoxylin-eosin staining to observe histopathological changes. Flow cytometry was performed to determine the percentage of γδT17 cells in the spleen and skin tissues, real-time reverse transcription (RT) -PCR to measure the mRNA expression of Hes1 in single cell suspension of the spleen, and enzyme-linked immunosorbent assay (ELISA) to determine the serum level of interleukin (IL) -17A. Statistical analysis was carried out by using one-way analysis of variance and repeated measures analysis of variance for comparison of indices among groups, and Pearson correlation analysis for evaluating the correlation between different indices. Results Twenty-four hours after the final treatment, the intervention group showed milder psoriasis-like skin inflammation, lower PASI score, and milder degree of epidermal thickening and dermal inflammatory cell infiltration compared with the model group. The model group showed significantly increased spleen index (12.534 ± 1.636) , proportions of γδT17 cells in the spleen (24.659% ± 4.603%) and skin tissues (22.127% ± 5.670%) , mRNA expression of Hes1 in the spleen (4.867 ± 0.543) , and serum level of IL-17A ([22.478 ± 2.776] ng/L) compared with the control group (all P < 0.01) . However, the above indices were significantly lower in the intervention group (9.449 ± 1.040, 14.966% ± 5.770%, 13.631% ± 5.946%, 2.541 ± 0.347, [18.639 ± 1.816] ng/L) than in the model group (all P < 0.01) . In the model group and intervention group, there were positive correlations between the proportions of γδT17 cells in the spleen and serum levels of IL-17A (r = 0.56, 0.53 respectively, both P < 0.05) , between the proportions of γδT17 cells in skin lesions and PASI scores (r = 0.56, 0.52 respectively, both P < 0.05) , as well as between the mRNA expression of Hes1 in the spleen and the proportions of γδT17 cells (r = 0.61, 0.58 respectively, both P < 0.05) or serum levels of IL-17A (r = 0.60, 0.54 respectively, both P < 0.05) . Conclusion Notch-Hes1 signaling blockade by γ-secretase inhibitor can markedly inhibit the expression of γδT17 cells, and effectively alleviate the severity of psoriasis-like skin inflammation in mouse models. Key words: Psoriasis; Amyloid precursor protein secretases; Receptors, Notch; Th17 cells; Interleukin-17; Hes1; γδT17 cells; γ-Secretase inhibitor

Role of bulge epidermal stem cells and TSLP signaling in psoriasis.

Psoriasis is a common inflammatory skin disease involving a cross‐talk between epidermal and immune cells. The role of specific epidermal stem cell populations, including hair follicle stem cells (HF‐SCs) in psoriasis is not well defined. Here, we show reduced expression of c‐JUN and JUNB in bulge HF‐SCs in patients with scalp psoriasis. Using lineage tracing in mouse models of skin inflammation with inducible deletion of c‐Jun and JunB, we found that mutant bulge HF‐SCs initiate epidermal hyperplasia and skin inflammation. Mechanistically, thymic stromal lymphopoietin (TSLP) was identified in mutant cells as a paracrine factor stimulating proliferation of neighboring non‐mutant epidermal cells, while mutant inter‐follicular epidermal (IFE) cells are lost over time. Blocking TSLP in psoriasis‐like mice reduced skin inflammation and decreased epidermal proliferation, VEGFα expression, and STAT5 activation. These findings unravel distinct roles of HF‐SCs and IFE cells in inflammatory skin disease and provide novel mechanistic insights into epidermal cell interactions in inflammation.

682 Characterization of a novel selective non-steroidal glucocorticoid receptor agonist with low systemic exposure and reduced potential for skin atrophy

Topical glucocorticoids (GCs) are widely used drugs in dermatology but are associated with both local and systemic adverse effects. With the aim to provide an effective but safer topical treatment, we here describe LEO 134310, a novel non-steroidal glucocorticoid receptor (GR) agonist with low systemic exposure and reduced potential for induction of skin atrophy. LEO 134310 is a full GR agonist with high affinity for GR and nanomolar potency in human PBMCs. Furthermore, selectivity for GR was demonstrated within a panel of nuclear hormone receptors, including the mineralocorticoid receptor, which has been associated with induction of skin atrophy. Topical treatment with LEO 134310 in human skin explants resulted in full agonism, measured by GR target engagement, with maximal effects comparable to BMV and CP, although at higher dosage strength. The lower potency of LEO 134310 in human skin explants could be explained by a combination of lower skin penetration, metabolism in the skin and in vitro potency. LEO 134310 was rapidly deactivated in the blood and other compartments by enzymatic hydrolysis, leading to low systemic exposure of active parent compound. Consequently, a 10-fold higher therapeutic index was achieved with LEO 134310 compared to BMV and CP in the TPA-induced skin inflammation mouse model. Induction of skin atrophy after topical treatment with LEO 134310 in minipigs was minimal in contrast to significant epidermal thinning induced by treatment with CP and BMV. In conclusion, LEO 134310 may potentially offer an improved topical treatment solution for patients with inflammatory skin diseases.

Cariniana domestica fruit peels present topical anti-inflammatory efficacy in a mouse model of skin inflammation.

To investigate the topical anti-inflammatory activity of the crude extract of Cariniana domestica fruit peels (CdE), its dichloromethane, n-butanol, and ethyl acetate (EtAc) fractions, and steroids (β-sitosterol, lupeol, and stigmasterol) isolated from the EtAc fraction in models of irritant contact dermatitis (ICD) croton oil-induced in mice. We induced skin inflammation by single (acute; 1mg/ear) and multiple (chronic; 0.4mg/ear) croton oil application. We topically applied C. domestica (CdE, fractions, and gel formulations) and β-sitosterol, lupeol, and stigmasterol immediately after applying croton oil. HPLC-DAD chromatography of the EtAc fraction and stability of the gel formulations were verified. HPLC-DAD of the EtAc fraction revealed the stigmasterol, lupeol, and β-sitosterol presence. CdE and EtAc fraction gels showed no organoleptic or pH changes at room temperatures. CdE and dichloromethane, n-butanol, and EtAc (1mg/ear) fractions decreased the acute ear edema with maximum inhibition (Imax) of 97 ± 2, 86 ± 1, 81 ± 4, and 95 ± 2%, respectively. CdE and EtAc fraction gel presented similar effects, with respective Imax of 85 ± 6% (3%;15mg/ear) and 82 ± 2% (1%;15mg/ear). β-sitosterol (7.5μg/ear), lupeol (10μg/ear), and stigmasterol (5.7μg/ear) also reduced this parameter by 46 ± 8, 51 ± 7, and 62 ± 7%, respectively. All topical treatments reduced the inflammatory cells' infiltration in the acute ICD model. CdE reduced the ear edema by 77 ± 4% (1mg/ear) and the inflammatory cell infiltration in the chronic ICD model. CdE's anti-inflammatory effect was accompanied by a minimum development of adverse effects. C. domestica demonstrates a promising potential for the development of a topical anti-inflammatory agent. Graphical abstract Cariniana domestica, popularly known as jequitibá-roxo, presented topical anti-inflammatory activity in an acute and chronic irritant contact dermatitis croton oil-induced in mice. The crude extract (solutions and gel formulations) and different fractions obtained from fruit peels of C. domestica showed topical antiinflammatory activity on skin inflammation models with minimum adverse effects in preliminary toxicological studies (behavior and biochemical parameters). Moreover, the HPLC analysis revealed the presence of β-sitosterol, stigmasterol and lupeol, which also presented topical anti-inflammatory effect in the acute irritant contact dermatitis croton oil-induced. Our findings support the use of this species as a promising topical antiinflammatory agent.

Neutralization of IL-17C Reduces Skin Inflammation in Mouse Models of Psoriasis and Atopic Dermatitis

IL-17C is a functionally distinct member of the IL-17 family that was believed to play a role in the pathogenesis of psoriasis. Here we confirmed that IL-17C is involved in psoriasis and explored potential roles for IL-17C in atopic dermatitis (AD). An anti-IL-17C antibody, MOR106, was generated that potently and selectively binds to human and mouse IL-17C, thereby inhibiting the binding of IL-17C to its IL-17RE receptor. The antibody inhibited cutaneous inflammation in an IL-23-induced psoriatic-like skin inflammation model. In lesional skin of patients with AD, IL-17C expression levels were increased and localized to keratinocytes and infiltrating immune cells. To determine the contribution of IL-17C to AD pathogenesis, MOR106 was tested in two distinct invivo models. In the calcipotriol-induced AD model, ear skin inflammation, TSLP, and IL-33 protein production in ears was suppressed by MOR106. Consistently, in the flaky tail strain mouse model, spontaneous development of AD-like skin inflammation was reduced by MOR106. Moreover, serum IgE levels, number of mast cells in skin and T helper type 2-related cytokines IL-4 and CCL17 in serum were all reduced. Overall, our resultsindicate that IL-17C is a central mediator of skin inflammation beyond psoriasis and is relevant in particular in AD.

Development of nanoparticles from natural lipids for topical delivery of thymol: Investigation of its anti-inflammatory properties.

Wound healing involves the integration of biological and molecular events and, in case of chronic wounds, the use of drugs can be associated to side effects. Therefore, there is a search for alternatives therapeutics that encompass minimal toxicity. The use of natural compounds is an attractive approach for treating inflammatory disorders, wounds and burns. In this context, thymol has antimicrobial, antioxidant and antiseptic properties and is a promising compound in wound healing and inflammation management. However, essential oils and their constituents such as thymol present high volatility and can also easily decompose, thereby the encapsulation of these compounds into nanoparticles may be an efficient approach to modulate the release of the active ingredient, to increase the physical stability and to eventually reduce the toxicity. The aims of this work were to encapsulate thymol in nanostructured lipid carriers (NLCs) composed of natural lipids and assess its in vivo anti-inflammatory and antipsoriatic activity. The carrier containing thymol was produced by sonication method and showed 107.7 (±3.8) nm of size, zeta potential of -11.6 (±2.9) mV and entrapment efficiency of 89.1 (±4.2)%. Thymol-NLCs were incorporated into a gel and the final formulation presented rheological characteristics and pH suitable for topic application. In addition, the gel containing thymol-NLCs was tested in vivo on two different mouse models of skin inflammation, showing anti-inflammatory activity. Finally, this formulation was tested in an imiquimod-induced psoriasis mouse model and showed improved healing, compared to negative control. Therefore, thymol-NLCs is an interesting formulation for future treatment of inflammatory skin diseases.

Topically Applied Carvedilol Attenuates Solar Ultraviolet Radiation Induced Skin Carcinogenesis.

In previous studies, the β-blocker carvedilol inhibited EGF-induced epidermal cell transformation and chemical carcinogen-induced mouse skin hyperplasia. As exposure to ultraviolet (UV) radiation leads to skin cancer, the present study examined whether carvedilol can prevent UV-induced carcinogenesis. Carvedilol absorbs UV like a sunscreen; thus, to separate pharmacological from sunscreen effects, 4-hydroxycarbazole (4-OHC), which absorbs UV to the same degree as carvedilol, served as control. JB6 P+ cells, an established epidermal model for studying tumor promotion, were used for evaluating the effect of carvedilol on UV-induced neoplastic transformation. Both carvedilol and 4-OHC (1 μmol/L) blocked transformation induced by chronic UV (15 mJ/cm2) exposure for 8 weeks. However, EGF-mediated transformation was inhibited by only carvedilol but not by 4-OHC. Carvedilol (1 and 5 μmol/L), but not 4-OHC, attenuated UV-induced AP-1 and NF-κB luciferase reporter activity, suggesting a potential anti-inflammatory activity. In a single-dose UV (200 mJ/cm2)-induced skin inflammation mouse model, carvedilol (10 μmol/L), applied topically after UV exposure, reduced skin hyperplasia and the levels of cyclobutane pyrimidine dimers, IL1β, IL6, and COX-2 in skin. In SKH-1 mice exposed to gradually increasing levels of UV (50-150 mJ/cm2) three times a week for 25 weeks, topical administration of carvedilol (10 μmol/L) after UV exposure increased tumor latency compared with control (week 18 vs. 15), decreased incidence and multiplicity of squamous cell carcinomas, while 4-OHC had no effect. These data suggest that carvedilol has a novel chemopreventive activity and topical carvedilol following UV exposure may be repurposed for preventing skin inflammation and cancer. Cancer Prev Res; 10(10); 598-606. ©2017 AACR.

MiR-146b Probably Assists miRNA-146a in the Suppression of Keratinocyte Proliferation and Inflammatory Responses in Psoriasis

miR-146a inhibits inflammatory responses in human keratinocytes and in different mouse models of skin inflammation. Little is known about the role of miR-146b in the skin. In this study, we confirmed the increased expression of miR-146a and miR-146b (miR-146a/b) in the lesional skin of patients with psoriasis. The expression of miR-146a was approximately twofold higher than that of miR-146b in healthy human skin, and it was more strongly induced by stimulation of proinflammatory cytokines in keratinocytes and fibroblasts. miR-146a/b target genes regulating inflammatory responses or proliferation were altered in the skin of patients with psoriasis, among which FERMT1 was verified as a direct target of miR-146a. In silico analysis of genome-wide data from >4,000 psoriasis cases and >8,000 controls confirmed a moderate association between psoriasis and genetic variants in the miR-146a encoding gene. Transfection of miR-146a/b suppressed and inhibition enhanced keratinocyte proliferation and the expression of psoriasis-related target genes. Enhanced expression of miR-146a/b-influenced genes was detected in cultured keratinocytes from miR-146a-/- and skin fibroblasts from miR-146a-/- and miR-146b-/- mice stimulated with psoriasis-associated cytokines as compared with wild-type mice. Our results indicate that besides miR-146a, miR-146b is expressed and might be capable of modulation of inflammatory responses and keratinocyte proliferation in psoriatic skin.

TRIM21 is important in the early phase of inflammation in the imiquimod-induced psoriasis-like skin inflammation mouse model.

Tripartite motif-containing protein 21 (TRIM21) regulates pro-inflammatory cytokines and type I interferons and acts as an autoantigen in certain autoimmune diseases, but TRIM21 has not been investigated in psoriasis. It has been suggested that TRIM21 may have a dual function; in the early phase of inflammation, it may function as a stimulator; but upon immune stimulation, its ubiquitinating mode of action may shift from stabilization to degradation of IRF3 causing inhibition of the immune responses. The imiquimod (IMQ)-induced psoriasis-like mouse model displays features similar to those of human psoriasis. However, chronicity is lacking in this model. We investigated whether the role of TRIM21 in psoriasis was pro-inflammatory or anti-inflammatory. We hypothesized that a shift of the TRIM21-ubiquitinating mode of action may explain the lack of chronicity in the IMQ-induced psoriasis-like mouse model. We showed that TRIM21 expression is increased in lesional psoriatic skin and in the early phase of IMQ-induced inflammation both in vitro and in vivo. Surprisingly, inflammation was significantly less pronounced in TRIM21 knockout mice than in wild-type mice as shown by ear thickness measured at days 8, 9 and 10 after treatment start, by spleen weight as a marker of systemic effect of IMQ at 10days after treatment start and by expression of IL-12p40 at days 3 and 10 after treatment start and IL-17A at day 3 after treatment start. Therefore, induction of TRIM21 expression cannot explain the lack of chronicity in the IMQ-induced psoriasis-like skin inflammation mouse model.

Multiple Immunosuppressive Effects of CpG-c41 on Intracellular TLR-Mediated Inflammation.

A growing body of literature suggests that most chronic autoimmune diseases are associated with inappropriate inflammation mediated by Toll-like receptor (TLR) 3, TLR7/8, or TLR9. Therefore, research into blocking TLR activation to treat these disorders has become a hot topic. Here, we report the immunomodulatory properties of a nonstimulatory CpG-containing oligodeoxynucleotide (CpG-ODN), CpG-c41, which had previously only been known as a TLR9 antagonist. In this study, we found that both in vitro and in vivo CpG-c41 decreased levels of various proinflammatory factors that were induced by single activation or coactivation of intracellular TLRs, but not membrane-bound TLRs, no matter what downstream signal pathways the TLRs depend on. Moreover, CpG-c41 attenuated excessive inflammation in the imiquimod-induced psoriasis-like mouse model of skin inflammation by suppressing immune cell infiltration and release of inflammatory factors. We also found evidence that the immunosuppressive effects of CpG-c41 on other intracellular TLRs are mediated by a TLR9-independent mechanism. These results suggest that CpG-c41 acts as an upstream of signaling cascades, perhaps on the processes of ligand internalization and transfer. Taken together, these results suggest that CpG-c41 disrupts various aspects of intracellular TLR activation and provides a deeper insight into the regulation of innate immunity.

Leptin deficiency in mice counteracts imiquimod (IMQ)-induced psoriasis-like skin inflammation while leptin stimulation induces inflammation in human keratinocytes.

Leptin is an adipocyte-derived cytokine secreted mostly by adipose tissue. Serum leptin levels are elevated in obese individuals and correlate positively with body mass index (BMI). Interestingly, serum leptin levels are also elevated in patients with psoriasis and correlate positively with disease severity. Psoriasis is associated with obesity; patients with psoriasis have a higher incidence of obesity, and obese individuals have a higher risk of developing psoriasis. Additionally, obese patients with psoriasis experience a more severe degree of psoriasis. In this study, we hypothesised that leptin may link psoriasis and obesity and plays an aggravating role in psoriasis. To investigate leptin's role in psoriasis, we applied the widely accepted imiquimod (IMQ)-induced psoriasis-like skin inflammation mouse model on leptin-deficient (ob/ob) mice and evaluated psoriasis severity. Moreover, we stimulated human keratinocytes with leptin and investigated the effect on proliferation and expression of pro-inflammatory proteins. In ob/ob mice, clinical signs of erythema, infiltration and scales in dorsal skin and inflammation in ear skin, as measured by ear thickness, were attenuated and compared with wt mice. Moreover, IL-17A and IL-22 mRNA expression levels, as well as increased epidermal thickness, were significantly less induced. In vitro, the effect of leptin stimulation on human keratinocytes demonstrated increased proliferation and induced secretion of several pro-inflammatory proteins; two hallmarks of psoriasis. In conclusion, leptin deficiency attenuated IMQ-induced psoriasis-like skin inflammation in a mouse model, and leptin stimulation induced a pro-inflammatory phenotype in human keratinocytes, thus, supporting an aggravating role of leptin in psoriasis.

Imiquimod-induced psoriasis-like skin inflammation in mouse model

&lt;p&gt;Psoriasis is a skin disorder characterized by skin inflammation and plaques. Induction of psoriasis in animal model include following steps: a) Selection of animal model, b) Hair removing from the back or ear, c) treatment of skin with Aldara, a cream containing 5% imiquimod and d) Observation. Imiquimod-induced skin inflammation in animal model resembles with psoriasis.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Video Clip:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;a href="https://youtube.com/v/QY-RESHbH-U"&gt;Psoriaisis-like skin:&lt;/a&gt; 9 min 10 sec&lt;/p&gt;

Efficacy and Pharmacology of the NLRP3 Inflammasome Inhibitor CP-456,773 (CRID3) in Murine Models of Dermal and Pulmonary Inflammation

A critical component of innate immune response to infection and tissue damage is the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome, and this pathway and its activation products have been implicated in the pathophysiology of a variety of diseases. NLRP3 inflammasome activation leads to the cleavage of pro-IL-1β and pro-IL-18, as well as the subsequent release of biologically active IL-1β, IL-18, and other soluble mediators of inflammation. In this study, we further define the pharmacology of the previously reported NLRP3 inflammasome-selective, IL-1β processing inhibitor CP-456,773 (also known as MCC950), and we demonstrate its efficacy in two in vivo models of inflammation. Specifically, we show that in human and mouse innate immune cells CP-456,773 is an inhibitor of the cellular release of IL-1β, IL-1α, and IL-18, that CP-456,773 prevents inflammasome activation induced by disease-relevant soluble and crystalline NLRP3 stimuli, and that CP-456,773 inhibits R848- and imiquimod-induced IL-1β release. In mice, CP-456,773 demonstrates potent inhibition of the release of proinflammatory cytokines following acute i.p. challenge with LPS plus ATP in a manner that is proportional to the free/unbound concentrations of the drug, thereby establishing an in vivo pharmacokinetic/pharmacodynamic model for CP-456,773. Furthermore, CP-456,773 reduces ear swelling in an imiquimod cream-induced mouse model of skin inflammation, and it reduces airway inflammation in mice following acute challenge with house dust mite extract. These data implicate the NLRP3 inflammasome in the pathogenesis of dermal and airway inflammation, and they highlight the utility of CP-456,773 for interrogating the contribution of the NLRP3 inflammasome and its outputs in preclinical models of inflammation and disease.

IL-23 induced in keratinocytes by endogenous TLR4 ligands polarizes dendritic cells to drive IL-22 responses to skin immunization.

Atopic dermatitis (AD) is a Th2-dominated inflammatory skin disease characterized by epidermal thickening. Serum levels of IL-22, a cytokine known to induce keratinocyte proliferation, are elevated in AD, and Th22 cells infiltrate AD skin lesions. We show that application of antigen to mouse skin subjected to tape stripping, a surrogate for scratching, induces an IL-22 response that drives epidermal hyperplasia and keratinocyte proliferation in a mouse model of skin inflammation that shares many features of AD. DC-derived IL-23 is known to act on CD4(+) T cells to induce IL-22 production. However, the mechanisms that drive IL-23 production by skin DCs in response to cutaneous sensitization are not well understood. We demonstrate that IL-23 released by keratinocytes in response to endogenous TLR4 ligands causes skin DCs, which selectively express IL-23R, to up-regulate their endogenous IL-23 production and drive an IL-22 response in naive CD4(+) T cells that mediates epidermal thickening. We also show that IL-23 is released in human skin after scratching and polarizes human skin DCs to drive an IL-22 response, supporting the utility of IL-23 and IL-22 blockade in AD.

Oncostatin M overexpression induces skin inflammation but is not required in the mouse model of imiquimod-induced psoriasis-like inflammation.

Oncostatin M (OSM) has been reported to be overexpressed in psoriasis skin lesions and to exert proinflammatory effects in vitro on human keratinocytes. Here, we report the proinflammatory role of OSM in vivo in a mouse model of skin inflammation induced by intradermal injection of murine OSM-encoding adenovirus (AdOSM) and compare with that induced by IL-6 injection. Here, we show that OSM potently regulates the expression of genes involved in skin inflammation and epidermal differentiation in murine primary keratinocytes. In vivo, intradermal injection of AdOSM in mouse ears provoked robust skin inflammation with epidermal thickening and keratinocyte proliferation, while minimal effect was observed after AdIL-6 injection. OSM overexpression in the skin increased the expression of the S100A8/9 antimicrobial peptides, CXCL3, CCL2, CCL5, CCL20, and Th1/Th2 cytokines, in correlation with neutrophil and macrophage infiltration. In contrast, OSM downregulated the expression of epidermal differentiation genes, such as cytokeratin-10 or filaggrin. Collectively, these results support the proinflammatory role of OSM when it is overexpressed in the skin. However, OSM expression was not required in the murine model of psoriasis induced by topical application of imiquimod, as demonstrated by the inflammatory phenotype of OSM-deficient mice or wild-type mice treated with anti-OSM antibodies.

Heme oxygenase-1-mediated anti-inflammatory effects of tussilagonone on macrophages and 12-O-tetradecanoylphorbol-13-acetate-induced skin inflammation in mice

The dried flower buds of Tussilago farfara L. have been used in traditional medicine, mainly as an antitussive in the treatment of cough and other respiratory problems. In the present study, we investigated the anti-inflammatory signaling pathway via the upregulation of heme oxygenase-1 (HO-1) in response to tussilagonone (TGN), a sesquiterpene compound isolated from T. farfara. TGN induced HO-1 expression and nuclear factor-E2-related factor 2 (Nrf2) activation in RAW 264.7 cells. Nuclear translocation of Nrf2 by TGN also increased in a time- and dose-dependent manner, indicating that TGN induced HO-1 via the Nrf2 pathway. Consistent with the notion that HO-1 has anti-inflammatory properties, TGN suppressed inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression and reduced the mRNA expression of proinflammatory cytokines, as well as nitric oxide (NO) and prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. TGN inhibited the phosphorylation and degradation of inhibitory κB-α (IκB-α) and the nuclear translocation of nuclear factor (NF)-κB. However, a specific inhibitor of HO-1 reversed the TGN-mediated suppression of NO production and knockdown of HO-1 by small interfering RNA abrogated inhibitory effects of TGN on iNOS and COX-2 protein expression and NF-κB nuclear translocation. Furthermore, TGN reduced iNOS and COX-2 expression in a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation mouse model. Taken together, these findings suggest an important role for TGN-induced HO-1 activation in regulating inflammatory responses. Moreover, TGN is a potent therapeutic candidate for targeting the crosstalk between Nrf2/HO-1 and the NF-κB signaling pathway in the prevention or treatment of inflammation-associated diseases.

Imiquimod Treatment Causes Systemic Disease in Mice Resembling Generalized Pustular Psoriasis in an IL-1 and IL-36 Dependent Manner.

Generalized pustular psoriasis (GPP) is a severe form of psoriasis that can be caused by missense mutations in the interleukin-36 (IL-36) receptor antagonist. In addition to neutrophil rich skin inflammation, GPP patients typically also experience anorexia, fever, malaise, and pain. The imiquimod-induced skin inflammation mouse model has rapidly become a popular way to study plaque psoriasis, which typically does not involve symptoms of systemic disease. In this model, neutrophil recruitment to the skin is dependent upon the inflammatory mediators IL-1, via its receptor IL-1R1, and IL-36α. Unexpectedly, we observed that mice also exhibited signs of anorexia (weight loss and decreased food intake), general malaise (decreased activity and loss of interest in building nests), and pain (nose bulging and hunched posture). A scoring system allowing quantitative comparisons of test groups was developed. Female mice were found to develop more severe disease than male mice. Furthermore, mice deficient in both IL-1R1 and IL-36α are nearly disease-free, while mice lacking only one of these inflammatory mediators have less severe disease than wild type mice. Hence, the imiquimod-induced skin inflammation mouse model recapitulates not only plaque psoriasis, but also the more severe symptoms, that is, anorexia, malaise, and pain, seen in GPP.