Interleukin-17 and interferon-gamma synergize in the enhancement of proinflammatory cytokine production by human keratinocytes

Preliminary study of histamine H4 receptor expressed on human CD4+ T cells and its immunomodulatory potency in the IL-17 pathway of psoriasis

BACKGROUND

Previous studies have shown the expression of histamine H₄ receptor (H4R) on CD4⁺ T cells, especially human CD4⁺ T_h2-polarized T cells.

OBJECTIVE

This study aimed to investigate the role of H4R on these effector T cells in psoriasis.

METHODS

We enrolled three patients each with active psoriasis, inactive psoriasis, scalp seborrheic dermatitis, and three normal controls, and compared the basal expression of H4R mRNA in their peripheral blood CD4⁺ T cells. Then, we identified H4R expression in dermal CD4⁺ T cells. Furthermore, we investigated H4R expression after stimulating separated peripheral blood CD4⁺ T cells with several inflammatory cytokines.

RESULTS

The results showed higher H4R expression in the active psoriasis group compared to the inactive psoriasis group. It was interesting that interleukin (IL)-23, which is a representative cytokine contributing to T_h17 cell differentiation, stimulated H4R expression significantly. After adding a selective H4R antagonist (JNJ-7777120) while the CD4⁺ T cells were polarized into T_h17 cells, we observed a tendency toward suppressed IL-17 secretion.

CONCLUSIONS

Histamine stimulation influences the IL-17 pathway in psoriasis via the fourth histamine receptor subtype, H4R, on CD4⁺ T cells. The immunomodulatory roles of H4R suggest its potency as a new therapeutic target for obstinate psoriasis.

IL-17 Blockade in Psoriasis

IL-17A both directly induces and synergizes with other cytokines to promote autoimmune tissue inflammation. Secukinumab and ixekizumab are monoclonal antibodies (mAb) that inhibit interleukin-17A. These two agents were recently approved for treatment of psoriasis, and secukinumab is also approved for treatment of two spondyloarthropathies, psoriatic arthritis and ankylosing spondylitis.

Helminth Immunomodulation in Autoimmune Disease

Helminths have evolved to become experts at subverting immune surveillance. Through potent and persistent immune tempering, helminths can remain undetected in human tissues for decades. Redirecting the immunomodulating "talents" of helminths to treat inflammatory human diseases is receiving intensive interest. Here, we review therapies using live parasitic worms, worm secretions, and worm-derived synthetic molecules to treat autoimmune disease. We review helminth therapy in both mouse models and clinical trials and discuss what is known on mechanisms of action. We also highlight current progress in characterizing promising new immunomodulatory molecules found in excretory/secretory products of helminths and their potential use as immunotherapies for acute and chronic inflammatory diseases.

Establishing a Role for Interleukin-17 in Atopic Dermatitis-Related Skin Inflammation

BACKGROUND

Although CD4⁺ T cells are known to contribute to the pathology of atopic dermatitis (AD), the role of T helper 17 cells and interleukin (IL)-17 in skin inflammation remains poorly understood. The aim of this study was to characterize the role of IL-17 in AD-related inflammation and immunopathology.

METHODS

Blood samples were collected from 87 children with AD and 60 healthy control subjects. In addition, 10 skin biopsies from each group were collected. Skin and serum expression levels of IL-17 were analyzed by immunohistochemistry and enzyme-linked immunosorbent assay, respectively. 2,4-Dinitrochlorobenzene (DNCB)-sensitized IL-17 knockout and wild-type mice were used as an animal model of skin AD. The messenger ribonucleic acid expression levels of T helper types 1 and 2 cytokines isolated from mouse skin biopsies were determined by quantitative polymerase chain reaction. Cytokine expression profiles of concanavalin A-stimulated splenocytes and IL-17-treated HaCaT keratinocytes were determined.

RESULTS

IL-17 expression levels were significantly elevated in the skin, but not in the serum, of patients with AD compared with healthy control subjects. Compared with control subjects, skin lesions from AD animal models exhibited significantly reduced epidermal and dermal thicknesses, as well as reduced messenger ribonucleic acid expression levels of T helper type 2 cytokines IL-4 and IL-13. Concanavalin A-stimulated splenocytes isolated from DNCB-treated IL-17 knockout mice showed significantly less production of IL-4 and IL-5 compared with wild-type controls. IL-6 and IL-8 production by IL-17-stimulated HaCaT cells was blocked by inhibitors of p38 kinase and extracellular signal-regulated kinase.

CONCLUSIONS

IL-17 may mediate AD-related immune dysregulation by amplifying the inflammatory response.

Inflammatory Disorders Associated with Allergy: Overview of Immunopathogenesis and Implications for Treatment

A number of chronic inflammatory diseases are associated with IgE-mediated immunologic hypersensitivity, including atopic dermatitis, chronic rhinosinusitis, and asthma. Pathogenetic studies of well-characterized patient groups has allowed investigators to more precisely define the molecular pathways involved in these diseases. Specific cytokines and chemokines, as well as other unique proteins, have now been identified in each of these common disorders and a number of medications are currently in development for inhibiting their actions. Continual refinement of our understanding of the pathogenesis of these diseases will undoubtedly yield increasingly precise, and potentially more effective, treatments.

Blocking IL-17A Alleviates Diabetic Retinopathy in Rodents

BACKGROUND/AIMS

Interleukin (IL)-17A, a proinflammatory cytokine, has been implicated in several autoimmune diseases. However, it is unclear whether IL-17A is involved in diabetic retinopathy (DR), one of the most serious complications of autoimmune diabetes. This study aimed to demonstrate that IL-17A exacerbates DR by affecting retinal Müller cell function.

METHODS

High glucose (HG)-treated rat Müller cell line (rMC-1) was exposed to IL-17A, anti-IL-17A-neutralizing monoclonal antibody (mAb) or/and anti-IL-17 receptor (R)A-neutralizing mAb for 24 h. For in vivo study, DR was induced by intraperitoneal injections of streptozotocin (STZ). DR model mice were treated with anti-IL-17A mAb or anti-IL-17RA mAb in the vitreous cavity. Mice that were prepared for retinal angiography were sacrificed two weeks after intravitreal injection, while the rest were sacrificed two days after intravitreal injection.

RESULTS

IL-17A production and IL-17RA expression were increased in both HG-treated rMC-1 and DR retina. HG induced rMC-1 activation and dysfunction, as determined by the increased GFAP, VEGF and glutamate levels as well as the downregulated GS and EAAT1 expression. IL-17A exacerbated the HG-induced rMC-1 functional disorders, whereas either anti-IL-17A mAb or anti-IL-17RA mAb alleviated the HG-induced rMC-1 disorders. Intravitreal injections with anti-IL-17A mAb or anti-IL-17RA mAb in DR model mice reduced Müller cell dysfunction, vascular leukostasis, vascular leakage, tight junction protein downregulation and ganglion cell apoptosis in the retina.

CONCLUSIONS

IL-17A aggravates DR-like pathology at least partly by impairing retinal Müller cell function. Blocking IL-17A is a potential therapeutic strategy for DR.

MCPIP1/Regnase-1 Restricts IL-17A- and IL-17C-Dependent Skin Inflammation

The IL-17 family cytokines IL-17A and IL-17C drive the pathogenesis of psoriatic skin inflammation, and anti-IL-17A Abs were recently approved to treat human psoriasis. Little is known about mechanisms that restrain IL-17 cytokine-mediated signaling, particularly IL-17C. In this article, we show that the endoribonuclease MCP-1-induced protein 1 (MCPIP1; also known as regnase-1) is markedly upregulated in human psoriatic skin lesions. Similarly, MCPIP1 was overexpressed in the imiquimod (IMQ)-driven mouse model of cutaneous inflammation. Mice with an MCPIP1 deficiency (Zc3h12a^+/-) displayed no baseline skin inflammation, but they showed exacerbated pathology following IMQ treatment. Pathology in Zc3h12a^+/- mice was associated with elevated expression of IL-17A- and IL-17C-dependent genes, as well as with increased accumulation of neutrophils in skin. However, IL-17A and IL-17C expression was unaltered, suggesting that the increased inflammation in Zc3h12a^+/- mice was due to enhanced downstream IL-17R signaling. Radiation chimeras demonstrated that MCPIP1 in nonhematopoietic cells is responsible for controlling skin pathology. Moreover, Zc3h12a^+/-Il17ra^-/- mice given IMQ showed almost no disease. To identify which IL-17RA ligand was essential, Zc3h12a^+/-Il17a^-/- and Zc3h12a^+/-Il17c^-/- mice were given IMQ; these mice had reduced but not fully abrogated pathology, indicating that MCPIP1 inhibits IL-17A and IL-17C signaling. Confirming this hypothesis, Zc3h12a^-/- keratinocytes showed increased responsiveness to IL-17A and IL-17C stimulation. Thus, MCPIP1 is a potent negative regulator of psoriatic skin inflammation through IL-17A and IL-17C. Moreover, to our knowledge, MCPIP1 is the first described negative regulator of IL-17C signaling.

Cytokines IL-17 and IL-22 in the host response to infection

Cytokines IL-17 and IL-22 play pivotal roles in host defense against microbes and in the development of chronic inflammatory diseases. These cytokines are produced by cells that are often located in epithelial barriers, including subsets of T cells and innate lymphoid cells. In general, IL-17 and IL-22 can be characterized as important cytokines in the rapid response to infectious agents, both by recruiting neutrophils and by inducing the production of antimicrobial peptides. Although each cytokine induces an innate immune response in epithelial cells, their functional spectra are generally distinct: IL-17 mainly induces an inflammatory tissue response and is involved in the pathogenesis of several autoimmune diseases, whereas IL-22 is largely protective and regenerative. In this review, we compare IL-17 and IL-22, describing overlaps and differences in their cellular sources as well as their regulation, signaling, biological functions and roles during disease, with a focus on the contribution of these cytokines to the gut mucosal barrier during bacterial infection.

Increased IL17A, IFNG, and FOXP3 Transcripts in Moderate-Severe Psoriasis: A Major Influence Exerted by IL17A in Disease Severity

Psoriasis is a chronic and recurrent dermatitis, mediated by keratinocytes and T cells. Several proinflammatory cytokines contribute to formation and maintenance of psoriatic plaque. The Th1/Th17 pathways and some of IL-1 family members were involved in psoriasis pathogenesis and could contribute to disease activity. Therefore, we sought to analyse skin transcript levels of IL17A, IL22, RORC, IL8, IFNG, IL33, IL36A, FOXP3, and IL10 and correlate with clinic of patients with plaque-type psoriasis. In order to conduct that, we collected punch biopsies from lesional skin and obtained tissue RNA. After reverse transcription, qRT-PCR quantified the relative mRNA expression. The main results revealed increased transcripts levels of IL17A, IFNG, and FOXP3 in moderate-severe patients. Despite this, only IL17A can increase the chance to worsen disease severity. We also observed many significant positive correlations between each transcript. In conclusion, IL17A is elevated in lesional skin from psoriasis patients and plays crucial role in disease severity.

Decreased expression of IL-27 in moderate-to-severe psoriasis and its anti-inflammation role in imiquimod-induced psoriasis-like mouse model

BACKGROUND

Psoriasis is a high-incident T-cell-mediated autoimmune disease mainly affecting the skin. Interleukin (IL)-27 is a novel member of the IL-6/IL-12 cytokine family, which plays a versatile role in the differentiation and function of distinct T cell subsets. Previous studies uncovered that IL-27 promoted the onset of psoriasis through enhancing the differentiation of T helper (Th) 1 cells. However, the role of IL-27 in other psoriasis-related Th lineages, especially Th17 cells, remains elusive.

OBJECTS

The study aimed to investigate the role of IL-27 in the progression of psoriasis and its underlying mechanisms, particularly its influence on Th1 and Th17.

METHODS

IL-27 and IL-27 receptor α (IL-27Rα) expressions in normal and lesional skin were determined by immunohistochemistry and western blot analysis. Serum levels of IL-27 and IL-10 were measured by ELISA. Expression levels of IL-27 and IL-27 receptor (IL-27R) mRNA in the skin tissue and peripheral blood mononuclear cells (PBMC) were assessed by quantitative polymerase chain reaction (PCR) analysis. To explore the function of IL-27 in vivo, we used imiquimod (IMQ)-induced psoriasis mouse model. We treated mice with IL-27 or its antagonist, evaluated disease severity and detected the cytokine secretion from splenic CD4+ T cells by flow cytometric analysis and the expression levels of IL-17 and IFN-γ in serum and skin lesion.

RESULTS

The expression levels of IL-27 and IL-27Rα were significantly reduced in the moderate-to-severe psoriatic lesions, along with a consistent decrease in serum IL-27 levels, compared with those of healthy control subjects. Moreover, subcutaneous administration of IL-27 recombinant protein lessened severity of IMQ-induced psoriasis-like cutaneous lesions, whereas IL-27p28 antagonist exaggerated the disease severity. Further analysis revealed that IL-27 significantly repressed IL-17 secretion from CD4+ T lymphocytes. Also administration of IL-27 decreased IL-17A level while IL-27p28 antagonist increased IL-17A level in serum and psoriasis-like lesion in the IMQ-treated mice.

CONCLUSION

Our results suggest that IL-27 might predominantly play a protective role in the pathogenesis of psoriasis through abrogating Th17 differentiation. The potential therapeutic benefit of harnessing IL-27 in treating psoriasis awaits future investigation.

A multistrain probiotic formulation attenuates skin symptoms of atopic dermatitis in a mouse model through the generation of CD4+Foxp3+ T cells

BACKGROUND

Atopic dermatitis (AD) is characterized by chronic inflammation of the skin. AD develops mainly in infants and young children. It induces skin disorders and signals the initiation of the allergic march including allergic asthma and rhinitis. Probiotics modify intestinal microbial populations in a beneficial way for human and animal hosts by reducing inflammatory cytokines.

OBJECTIVE

As a result of their immunomodulatory properties, probiotics have been considered a promising therapeutic option for the prevention and treatment of AD.

DESIGN

In this study, we examined the effects of GI7, a potential probiotic mixture consisting of seven strains of bifidobacteria and lactic acid bacteria, on AD in a mouse model.

RESULTS

Administration of GI7 for 8 weeks reduced AD-like skin lesions and induced changes in the levels of serum markers such as immunoglobulin E and cytokines related to T helper (Th)1 and Th2 cells, and in skin barrier genes. Alleviation of AD seems to be associated with GI7-induced generation of CD4⁺Foxp3⁺ regulatory T cells.

CONCLUSIONS

The probiotic mixture may have potential to improve symptoms of AD.

Cytokine and chemokine profiles of aqueous humor and serum in horses with uveitis measured using multiplex bead immunoassay analysis

OBJECTIVE

To determine whether horses with clinically diagnosed Equine Recurrent Uveitis (ERU) and those with Leptospirosis infection have a specific cytokine profile in their aqueous humor (AH) and serum that differs from horses with uveitis secondary to other ocular inflammatory processes and from horses with normal eyes.

ANIMALS STUDIED

Twenty-five client-owned horses with uveitis that were presented to the North Carolina State University Ophthalmology Service, and four University-owned horses without history or clinical signs of ocular disease.

PROCEDURE

Samples of AH and serum were obtained from horses with ERU (n=13), acute or non-recurrent uveitis (UV; n=7), uveitis secondary to infectious keratitis (IK; n=5), and normal eyes (N; n=4). Cytokine levels in AH and serum were quantified using a multiplex bead immunoassay. Leptospiral antibody titers in serum and AH and PCR for Leptospiral DNA in AH were performed.

RESULTS

In the AH of horses with ERU, increased levels of IL-1a, IL-4, IL-6, IL-8, IL-12p70, FGF-2, G-CSF, and RANTES were measured compared to UV, IK and N eyes, but the differences were not significant. However, IL-10 was significantly higher in ERU eyes compared to IK and N (P=0.029; 0.013), and IP-10 in ERU eyes was significantly higher than in UV and N (P=0.004). Furthermore, MCP-1 was significantly higher in ERU than N (P=0.04). In the serum, increased levels of IL-1a, IL-4, IL-6, IL-8, IL-12p70, fractalkine, and G-CSF were measured in horses with ERU, but the levels were not significantly higher than those observed in UV, IK, or N horses. However, serum IP-10 levels in horses with ERU were significantly higher than in UV and N horses (P=0.005) and MCP-1 levels were significantly higher in ERU than N (P=0.03). Horses with marked ocular inflammation had significantly higher serum levels of G-CSF, IL-1a, fractalkine, IL-13, IL-4, IL-17a, IL-12p70, IFN-γ, and MCP-1. Elevated IL-10 in AH was significantly associated with disease chronicity, both overall and in ERU eyes (P=0.049), and in horses with positive ocular leptospiral titers or leptospiral PCR, significant elevations of IL-10 (P=0.0018; 0.0032) and IP-10 (P=0.0342; 0.043) were detected in the AH compared to leptospiral negative eyes.

CONCLUSIONS

The anti-inflammatory cytokine IL-10 and the pro-inflammatory cytokine IP-10 appear to play an important role in ERU. Further studies are needed to further clarify and characterize cytokine profiles of specific ocular inflammatory diseases, but multiplex bead immunoassay technology shows promise as a diagnostically valuable tool.

Characterization of Th17 and FoxP3(+) Treg Cells in Paediatric Psoriasis Patients

Psoriasis is one of the most common inflammatory skin conditions affecting both children and adults. Growing evidence indicates that T-helper 17 (Th17) cells and CD4(+) CD25(+) regulatory T (Treg) cells play an important role in the pathogenesis of psoriasis. However, the relationship between Th17 and Treg cells and their dynamic variations in paediatric psoriasis remain unclear. In this study, we found that both Th17 and FoxP3(+) Treg cells and the ratio of Th17 to Treg cell frequency in the peripheral circulation were increased in patients with paediatric psoriasis and were positively correlated with the disease severity. The function of Treg to suppress CD4(+) CD25(-) T cell proliferation and IFN-γ secretion was impaired during the onset of psoriasis. After disease remission, both the Th17 and Treg cell frequencies were decreased, and the suppressive function of the Treg cells was obviously restored. However, neither Treg cells from the disease onset nor those after remission can regulate IL-17 secretion by CD4(+) T cells. These findings will further our understanding of the associations between Th17 and Treg cells in paediatric psoriasis and their influence on disease severity.

Circulating T-helper 17 cells and associated cytokines in psoriasis

BACKGROUND

Recently, a new population of IL-17-producing CD4 T helper (Th) cells, named Th17, was identified and shown to be involved in various inflammatory and autoimmune diseases, including psoriasis.

AIM

To determine the frequency of Th17 cells and related cytokines in peripheral blood of patients with psoriasis, and to analyse their association with disease severity.

METHODS

This was a prospective study comprising 34 patients with psoriasis and 24 healthy controls. Clinicoepidemiological details of patients were recorded, and severity of psoriasis was assessed by means of the Psoriasis Area and Severity Index. Circulating Th1 and Th17 cells in untreated patients with psoriasis and healthy controls were quantified by flow cytometry. In sera collected from patients with psoriasis and healthy controls, concentrations of IL-17A and IL-23 were examined by ELISA.

RESULTS

Increased frequencies of CD4+ IL-17A+ T cells were seen in peripheral blood of patients with psoriasis vulgaris (P < 0.001). Although serum IL-17A and IL-23 concentrations were higher in patients with psoriasis than in controls, the results did not reach statistical significance. We could not find any correlation between the studied T cells or related cytokines and the disease severity.

CONCLUSION

Increased serum levels of circulating Th17 cells and related cytokines may contribute to the cutaneous pathology of psoriasis, as well as the inflammatory process that is a hallmark of psoriasis.

T-helper 17 cytokines (interleukins 17, 21, 22, and 6, and tumor necrosis factor-α) in patients with alopecia areata: association with clinical type and severity

BACKGROUND

Alopecia areata (AA) is an organ-specific autoimmune disease characterized by T-cell infiltrates and cytokine production. T-helper 17 (Th17) cells are crucially involved in the pathogenesis of autoimmune diseases.

OBJECTIVES

Our aim was to assess the association of Th17 with AA. We examined interleukin (IL)-17, IL-21, IL-22, IL-6, and tumor necrosis factor-alpha (TNF-α) levels in the serum of patients with AA and studied their association with clinical type and severity of AA.

SUBJECTS AND METHODS

The serum concentrations of IL-17, IL-21, IL-22, IL-6, and TNF-α were measured in 47 patients with AA and 40 healthy controls. The clinical type of AA was determined, and the severity of hair loss was assessed in accordance with the Alopecia Areata Investigational Assessment Guideline criteria.

RESULTS

The serum concentrations of IL-17, IL-21, IL-22, IL-6, and TNF-α were significantly higher in patients with AA as compared with healthy controls (mean: IL-17 33.23 ± 11.58 vs. 4.62 ± 1.88 pg/ml; P = 0.000, IL-21 62.10 ± 6.11 vs. 48.38 ± 3.31 pg/ml; P = 0.000, IL-22 19.27 ± 3.36 vs. 7.09 ± 1.62 pg/ml; P = 0.000, IL-6 17.18 ± 3.08 vs. 4.59 ± 1.66 pg/ml; P = 0.000, TNF-α 19.94 ± 3.59 vs. 9.95 ± 2.42 pg/ml; P = 0.000, respectively). There were significant positive correlations between serum IL-17, TNF-α, and disease severity. There was also significant positive correlation between serum IL-22 and duration of AA.

CONCLUSION

Our results showed high serum levels of Th17 cytokines among patients with AA that may suggest a functional role of these cytokines in the pathogenesis of this important skin disease. It could also provide the rationale for new treatment strategies in AA.

IL-17+ CD8+ T cells: Differentiation, phenotype and role in inflammatory disease

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IL-17A (IL-17) is produced by multiple cell subsets, including CD8+ T cells.

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The presence of IL-17+ CD8+ T cells in human inflammatory diseases suggests these cells may contribute to immunopathology.

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Increased knowledge of human IL-17+ CD8+ T cells will enhance our overall understanding of their role in human disease.

The pro-inflammatory cytokine interleukin-17A (IL-17) has been the subject of research by many groups worldwide. IL-17 expression is often associated with a specific subset of CD4+ T cells (the so-called Th17 cells); however various other immune cell subsets can also synthesise and express IL-17, including CD8+ T cells. Here we review recent data regarding the presence of IL-17+ CD8+ T cells (also known as Tc17 cells) in human inflammatory disease, discuss current knowledge regarding the culture conditions required for the differentiation of these cells in humans and mice, and describe key phenotypic and functional features. Collectively, this information may shed light on the potential pathogenic role that IL-17+ CD8+ T cells may play in human inflammatory disease.

Therapeutic antibodies that target inflammatory cytokines in autoimmune diseases

Inflammatory cytokines are key regulators of immune responses. Persistent and excessive production of inflammatory cytokines underscores the development of autoimmune diseases. Therefore, neutralizing inflammatory cytokines or antagonizing their receptor function is considered as a useful therapeutic strategy to treat autoimmune diseases. To achieve the success of such a strategy, understanding of the complex actions of these cytokines and cytokine networks is required. In this review we focus on four inflammatory cytokines--tumor necrosis factor α (TNFα), interleukin-6 (IL-6), IL-23 and IL-17--and dissect how the dysregulation of these cytokines regulates autoimmune diseases. On the basis of pre-clinical and clinical data, we specifically discuss the therapeutic rationale for targeting these cytokines and describe the potential adverse effects.

Crohn's disease and skin

Crohn's disease is a chronic inflammatory bowel disease potentially involving any segment of the gastrointestinal tract. Extra-intestinal manifestations may occur in 6%-40% of patients, and disorders of the skin are among the most common. This manuscript will review skin manifestations associated to Crohn's disease, with a particular focus on lesions associated to anti-tumour necrosis factor therapy.

The roles and functional mechanisms of interleukin-17 family cytokines in mucosal immunity

The mucosal immune system serves as our front-line defense against pathogens. It also tightly maintains immune tolerance to self-symbiotic bacteria, which are usually called commensals. Sensing both types of microorganisms is modulated by signalling primarily through various pattern-recognition receptors (PRRs) on barrier epithelial cells or immune cells. After sensing, proinflammatory molecules such as cytokines are released by these cells to mediate either defensive or tolerant responses. The interleukin-17 (IL-17) family members belong to a newly characterized cytokine subset that is critical for the maintenance of mucosal homeostasis. In this review, we will summarize recent progress on the diverse functions and signals of this family of cytokines at different mucosal edges.

What's new in the physiopathology of acne?

There are four central factors that contribute to acne physiopathology: the inflammatory response, colonization with Propionibacterium acnes, increased sebum production and hypercornification of the pilosebaceous duct. In addition, research in the areas of diet and nutrition, genetics and oxidative stress is also yielding some interesting insights into the development of acne. In this paper we review some of the most recent research and novel concepts revealed in this work, which has been published by researchers from diverse academic disciplines including dermatology, immunology, microbiology and endocrinology. We discuss the implications of their findings (particularly in terms of opportunities to develop new therapies), highlight interrelationships between these novel factors that could contribute to the pathology of acne, and indicate where gaps in our understanding still exist.

Inhibition of imiquimod-induced psoriasis-like dermatitis in mice by herbal extracts from some Indian medicinal plants

Psoriasis is a chronic autoimmune human skin disorder that is characterized by excessive proliferation of keratinocytes, scaly plaques, severe inflammation and erythema. The pathophysiology of psoriasis involves interplay between epidermal keratinocytes, T lymphocytes, leukocytes and vascular endothelium. Increased leukocyte recruitment and elevated levels of cytokines, growth factors and genetic factors like interleukin (IL)-1β, IL-6, IL-17, IL-22, IL-23, tumour necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, toll-like receptor (TLR)-2, signal transducer and activator of transcription (STAT-3), 15-lipoxygenase (LOX)-2, coiled-coil alpha-helical rod protein 1 (CCHCR1), steroidogenic acute regulatory protein (StAR) and vitamin D receptor (VDR) are the most critical factors governing the exacerbation of psoriasis. In the present study, an attempt was made to elucidate the preventive role of herbal extracts of four dermo-protective Ayurvedic plants, Tinospora cordifolia (TC), Curcuma longa (CL), Celastrus paniculatus (CP) and Aloe vera (AV), against psoriasis-like dermatitis. Parkes (P) strain mice were initially induced with psoriasis-like dermatitis using topical application of imiquimod (IMQ, 5 %), followed by subsequent treatment with the herbal extracts to examine their curative effect on the psoriasis-like dermatitis-induced mice. The extracts were orally/topically administered to mice according to their ED/LD50 doses. Phenotypical observations, histological examinations, and semi-quantitative reverse transcription PCR (RT-PCR) analyses of the skin and blood samples of the control, IMQ-treated and herbal extract-treated psoriasis-like dermatitis-induced mice lead to the conclusion that the combination extract from all the plants was instrumental in downregulating the overexpressed cytokines, which was followed by the CL extract. Moreover, lesser yet positive response was evident from CP and TC extracts. The results suggest that these plants can prove to have tremendous preventive potential against the disease and can open the way to new therapeutic strategies for psoriasis treatment.

A sand fly salivary protein vaccine shows efficacy against vector-transmitted cutaneous leishmaniasis in nonhuman primates

Currently, there are no commercially available human vaccines against leishmaniasis. In rodents, cellular immunity to salivary proteins of sand fly vectors is associated to protection against leishmaniasis, making them worthy targets for further exploration as vaccines. We demonstrate that nonhuman primates (NHP) exposed to Phlebotomus duboscqi uninfected sand fly bites or immunized with salivary protein PdSP15 are protected against cutaneous leishmaniasis initiated by infected bites. Uninfected sand fly-exposed and 7 of 10 PdSP15-immunized rhesus macaques displayed a significant reduction in disease and parasite burden compared to controls. Protection correlated to the early appearance of Leishmania-specific CD4(+)IFN-γ(+) lymphocytes, suggesting that immunity to saliva or PdSP15 augments the host immune response to the parasites while maintaining minimal pathology. Notably, the 30% unprotected PdSP15-immunized NHP developed neither immunity to PdSP15 nor an accelerated Leishmania-specific immunity. Sera and peripheral blood mononuclear cells from individuals naturally exposed to P. duboscqi bites recognized PdSP15, demonstrating its immunogenicity in humans. PdSP15 sequence and structure show no homology to mammalian proteins, further demonstrating its potential as a component of a vaccine for human leishmaniasis.

Interleukin-17 potently increases non-small cell lung cancer growth

The aim of the present study was to explore the effects of interleukin (IL)-17 on the growth and metastasis of tumors that were subcutaneously implanted into C57BL/6 mice. Lewis lung carcinoma (LLC) cells were subcutaneously injected into C57BL/6 mice followed by intraperitoneal injection of mouse recombinant IL-17 protein (IL-17 groups) or phosphate-buffered saline (control groups). Tumor growth and metastasis were assessed by measuring the size and weight of tumors and cervical lymph nodes, respectively. Cytokine expression in tumor masses was quantified by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. CCR2-positive macrophage infiltration in tumor masses was detected by flow cytometric analysis. The proliferation and migration of LLC cells, stimulated by the IL-17 protein were detected by Cell Counting kit (CCK)-8 and wound scratch assays in vitro. Tumors were grafted into the C57BL/6 mice. The mice that were intraperitoneally injected with IL-17 exhibited significantly larger tumors compared with the control mice. After day 7 of injection and beyond, the weight of cervical lymph nodes in IL-17 groups was higher than that in the control mice. It was also demonstrated that the number of CCR2-positive macrophages that infiltrated the tumor masses in the IL-17 groups was higher than that of the control mice. CD34 expression in vascular endothelial cells was also higher in tumors grafted in IL-17 mice than those grafted in control mice. Furthermore, the tumor tissue mRNA and protein expression levels of vascular endothelial growth factor, matrix metalloproteinase (MMP)-2, MMP-9 and tumor necrosis factor-α were greater in mice from the IL-17 group than the control mice, while levels of migration inhibitory factor and thrombospondin-1 were lower in mice from the IL-17 group than in the control. IL-17 also increased the migration of LLC cells in vitro. In conclusion, IL-17 exhibited the ability to promote tumor growth by increasing angiogenesis, metastasis and increasing CCR2+ macrophage infiltration into tumors.

Advances in T Helper 17 Cell Biology: Pathogenic Role and Potential Therapy in Multiple Sclerosis

The discovery of the T helper (Th) 17 lineage, involved in the protection against fungal and extracellular bacterial infections, has profoundly revolutionized our current understanding of T cell-mediated responses in autoimmune diseases, including multiple sclerosis (MS). Indeed, recent data demonstrate the pathogenic role of Th17 cells in autoimmune disorders. In particular, studies in MS and in its animal model (EAE, experimental autoimmune encephalomyelitis) have revealed a crucial role of Th17 cells in the pathogenesis of autoimmune demyelinating diseases in both mice and humans. Over the past years, several important aspects concerning Th17 cells have been elucidated, such as the factors which promote or inhibit their differentiation and the effector cytokines which mediate their responses. The identification of the features endowing Th17 cells with high pathogenicity in MS is of particular interest, and discoveries in Th17 cell biology and function could lead to the design of new strategies aimed at modulating the immune response in MS. Here, we will discuss recent advances in this field, with particular focus on the mechanisms conferring pathogenicity in MS and their potential modulation.

Update on psoriasis immunopathogenesis and targeted immunotherapy

Over recent years, significant progress has been made in characterisation of the underlying pathogenic mechanisms in psoriasis, a common cutaneous disease that is associated with major systemic co-morbidity and reduced life expectancy. Basic science discoveries have informed the design of novel therapeutic approaches, many of which are now under evaluation in late-stage clinical trials. Here we describe the complex interplay between immune cell types and cytokine networks that acts within self-perpetuating feedback loops to drive cutaneous inflammation in psoriasis. Genetic studies have been pivotal in the construction of the disease model and more recently have uncovered a distinct aetiology for rare, pustular variants of psoriasis. The translation of mechanistic insights into potential advancements in clinical care will also be described, including several treatments that target the interleukin-23 (IL-23)/T17 immune axis.

Phase 3 Studies Comparing Brodalumab with Ustekinumab in Psoriasis

BACKGROUND

Early clinical studies suggested that the anti-interleukin-17 receptor A monoclonal antibody brodalumab has efficacy in the treatment of psoriasis.

METHODS

In two phase 3 studies (AMAGINE-2 and AMAGINE-3), patients with moderate-to-severe psoriasis were randomly assigned to receive brodalumab (210 mg or 140 mg every 2 weeks), ustekinumab (45 mg for patients with a body weight ≤100 kg and 90 mg for patients >100 kg), or placebo. At week 12, patients receiving brodalumab were randomly assigned again to receive a brodalumab maintenance dose of 210 mg every 2 weeks or 140 mg every 2 weeks, every 4 weeks, or every 8 weeks; patients receiving ustekinumab continued to receive ustekinumab every 12 weeks, and patients receiving placebo received 210 mg of brodalumab every 2 weeks. The primary aims were to evaluate the superiority of brodalumab over placebo at week 12 with respect to at least a 75% reduction in the psoriasis area-and-severity index score (PASI 75) and a static physician's global assessment (sPGA) score of 0 or 1 (clear or almost clear skin), as well as the superiority of brodalumab over ustekinumab at week 12 with respect to a 100% reduction in PASI score (PASI 100).

RESULTS

At week 12, the PASI 75 response rates were higher with brodalumab at the 210-mg and 140-mg doses than with placebo (86% and 67%, respectively, vs. 8% [AMAGINE-2] and 85% and 69%, respectively, vs. 6% [AMAGINE-3]; P<0.001); the rates of sPGA scores of 0 or 1 were also higher with brodalumab (P<0.001). The week 12 PASI 100 response rates were significantly higher with 210 mg of brodalumab than with ustekinumab (44% vs. 22% [AMAGINE-2] and 37% vs. 19% [AMAGINE-3], P<0.001). The PASI 100 response rates with 140 mg of brodalumab were 26% in AMAGINE-2 (P=0.08 for the comparison with ustekinumab) and 27% in AMAGINE-3 (P=0.007). Rates of neutropenia were higher with brodalumab and with ustekinumab than with placebo. Mild or moderate candida infections were more frequent with brodalumab than with ustekinumab or placebo. Through week 52, the rates of serious infectious episodes were 1.0 (AMAGINE-2) and 1.3 (AMAGINE-3) per 100 patient-years of exposure to brodalumab.

CONCLUSIONS

Brodalumab treatment resulted in significant clinical improvements in patients with moderate-to-severe psoriasis. (Funded by Amgen; AMAGINE-2 and AMAGINE-3 ClinicalTrials.gov numbers, NCT01708603 and NCT01708629.).

Potential role of Th17 cells in the pathogenesis of type 2 autoimmune pancreatitis

Th17 cells have been shown to play an important role in the pathogenesis of a variety of autoimmune diseases. The aim of this study was to investigate the potential role of Th17 cells in autoimmune pancreatitis (AIP). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine gene expression of the signature cytokines of Th17 cells IL-17A and IL-21 and of the Th17 lineage-specific transcription factor retinoic acid receptor-related orphan receptor C (RORC) in human tissue specimens of AIP, classical chronic pancreatitis (CP), and normal pancreas (NP). Infiltrating immune cells were characterized by immunohistochemistry (IHC). Gene expression of IL-17A, IL-21, and RORC were found to be significantly increased in AIP. Accordingly, the number of Th17 cells was significantly increased in AIP compared to NP or CP. Both gene expression analysis and IHC revealed a clear difference between type 1 and 2 AIP. In the periductal compartment of type 2 AIP, which is characterized by granulocytic epithelial lesions (GELs), the number of infiltrating Th17 cells and neutrophilic granulocytes was significantly increased compared to type 1 AIP. Our data suggest that Th17 cells play a role in the pathogenesis of AIP, in particular of type 2 AIP. Cross-talk between Th17 cells and neutrophilic granulocytes mediated via IL-17A may be a potential mechanism by which neutrophils are recruited to the duct and acinar cells with subsequent destruction, a process that is pathognomonic for type 2 AIP.

Targeting IL-17 with ixekizumab in patients with psoriasis

Psoriasis is a multifactorial chronic inflammatory skin disease of unknown etiology. Knowledge of the pathophysiology of psoriasis has evolved and identified IL-17 as a key pro-inflammatory mediator in psoriasis creating new medical avenues. Several agents targeting IL-17 or its receptor are in clinical trials for the treatment of moderate-to-severe psoriasis. This review focuses on the biological rationale and the results of clinical trials with ixekizumab, a humanized IgG4 monoclonal antibody. The currently available Phase I to III data indicate that ixekizumab is a well-tolerated promising drug, although long-term data of efficacy and safety are needed before ixekizumab and other IL-17 targeting therapeutics can find their place in clinical practice.

Mining the human autoantibody repertoire: isolation of potent IL17A-neutralizing monoclonal antibodies from a patient with thymoma

Anti-cytokine autoantibodies have been widely reported to be present in human plasma, both in healthy subjects and in patients with underlying autoimmune conditions, such as autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) or thymic epithelial neoplasms. While often asymptomatic, they can cause or facilitate a wide range of diseases including opportunistic infections. The potential therapeutic value of specific neutralizing anti-cytokine autoantibodies has not been thoroughly investigated. Here we used mammalian cell display to isolate IL17A-specific antibodies from a thymoma patient with proven high-titer autoantibodies against the same. We identified 3 distinct clonotypes that efficiently neutralized IL17A in a cell-based in vitro assay. Their potencies were comparable to those of known neutralizing antibodies, including 2, AIN457 (secukinumab) and ixekizumab that are currently in clinical development for the treatment of various inflammatory disorders. These data clearly demonstrate that the human autoantibody repertoire can be mined for antibodies with high therapeutic potential for clinical development.

HSP27 modulates survival signaling in endosulfan-exposed human peripheral blood mononuclear cells treated with curcumin

Endosulfan, a well-known organochlorine pesticide, induces apoptosis and depletion of reduced glutathione (GSH) in human peripheral blood mononuclear cells (PBMC). Thus, for the amelioration of its effect, antioxidant and antiapoptotic potential of curcumin was evaluated. For ascertaining the attenuating effect of curcumin, various biochemical indices of cell damage such as cytotoxicity, oxidative stress, apoptosis (phosphatidylserine externalization, DNA fragmentation, and cytochrome c) in human PBMC was evaluated following endosulfan exposure (0-100 µM). To assess the role of HSP27 on endosulfan-induced apoptosis, the expression of HSP27 was examined. Curcumin (25 µM) increased cell viability significantly. As evident from the restoration of GSH, antiapoptotic potential was directly proportional to their antioxidant nature of curcumin. The present study indicates that the beneficial effect of curcumin on endosulfan-induced cytotoxicity is related to the induced synthesis of HSP27, emphasizing its antioxidant and therapeutic potential as well as underscoring the mechanism of pesticide-induced toxicity at cellular level. Taken together, these findings suggest that curcumin protects against endosulfan-induced immunotoxicity in human PBMC by attenuating apoptosis.

The role of Th17-associated cytokines in the pathogenesis of experimental autoimmune uveitis (EAU)

The proinflammatory and pathogenic function of Th17 cells in autoimmune diseases have been established but the mechanism by which such cells cause disease remains to be determined. Inflammatory cytokines produced by Th17 cells may either promote or inhibit disease development. The major cytokines produced by the uveitogenic T cells, such as IL-17 and IL-22, are not always pathogenic, and the disease-inducing ability of pathogenic T cells is not immediately correlated to the amount of cytokine they produce. Future studies identifying factors causing increased Th17 responses and determining the types of cells that regulating Th17 autoreactive T cells should facilitate our effort of understanding Th17-mediated disease pathogenesis.

Cross Talk between Proliferative, Angiogenic, and Cellular Mechanisms Orchestred by HIF-1α in Psoriasis

Psoriasis is a chronic inflammatory skin disease where the altered regulation in angiogenesis, inflammation, and proliferation of keratinocytes are the possible causes of the disease, and the transcription factor “hypoxia-inducible factor 1-alpha” (HIF-1α) is involved in the homeostasis of these three biological phenomena. In this review, the role of HIF-1α in the cross talk between the cytokines and cells of the immunological system involved in the pathogenesis of psoriasis is discussed.

Therapeutic Potential of IL-17-Mediated Signaling Pathway in Autoimmune Liver Diseases

Emerging evidence reveals that various cytokines and tissue microenvironments contribute to liver inflammation and autoimmunity, and IL-17 family is one of highlights acknowledged. Although the implication of IL-17 family in most common autoimmune diseases (such as psoriasis, inflammatory bowel disease, and rheumatoid arthritis) has been extensively characterized, the role of this critical family in pathophysiology of autoimmune liver diseases (AILD) still needs to be clarified. In the review, we look into the intriguing biology of IL-17 family and further dissect on the intricate role of IL-17-mediated pathway in AILD. Considering encouraging data from preclinical and clinical trials, IL-17 targeted therapy has shown promises in several certain autoimmune conditions. However, blocking IL-17-mediated pathway is just beginning, and more fully investigation and reflection are required. Taking together, targeting IL-17-mediated responses may open up new areas of potential clinical treatment for AILD.

IL-17A gene transfer induces bone loss and epidermal hyperplasia associated with psoriatic arthritis

BACKGROUND

Psoriatic arthritis (PsA) is a chronic inflammatory disease characterised by clinical features that include bone loss and epidermal hyperplasia. Aberrant cytokine expression has been linked to joint and skin pathology; however, it is unclear which cytokines are critical for disease initiation. Interleukin 17A (IL-17A) participates in many pathological immune responses; however, its role in PsA has not been fully elucidated.

OBJECTIVE

To determine the role of IL-17A in epidermal hyperplasia and bone destruction associated with psoriatic arthritis.

DESIGN

An in vivo gene transfer approach was used to investigate the role of IL-17A in animal models of inflammatory (collagen-induced arthritis) and non-inflammatory (receptor activator of NF-κB ligand (RANKL)-gene transfer) bone loss.

RESULTS

IL-17A gene transfer induced the expansion of IL-17RA(+)CD11b(+)Gr1(low) osteoclast precursors and a concomitant elevation of biomarkers indicative of bone resorption. This occurred at a time preceding noticeable joint inflammation, suggesting that IL-17A is critical for the induction of pathological bone resorption through direct activation of osteoclast precursors. Moreover, IL-17A induced a second myeloid population CD11b(+)Gr1(high) neutrophil-like cells, which was associated with cutaneous pathology including epidermal hyperplasia, parakeratosis and Munro's microabscesses formation.

CONCLUSIONS

Collectively, these data support that IL-17A can play a key role in the pathogenesis of inflammation-associated arthritis and/or skin disease, as observed in PsA.

Ixekizumab for treatment of psoriasis

Psoriasis is a prevalent chronic inflammatory skin disease of unknown etiology. Recent advances in understanding the pathogenesis of psoriasis suggest that IL-17 is a key proinflammatory mediator present in the skin. Several agents targeting IL-17 or its receptor are in clinical trials for the treatment of psoriasis. This review focuses on the biological rationale and the results of clinical trials with ixekizumab, a humanized IgG4 monoclonal antibody. Ixekizumab binds the IL-17A homodimer, thereby blocking the binding of IL-17A to the IL-17 receptor. The currently available Phase I-III data indicate that ixekizumab is a promising drug, although long-term data of efficacy and safety are needed before ixekizumab and other IL-17 targeting therapeutics can find their place in clinical practice.

Cytokine crowdsourcing: multicellular production of TH17-associated cytokines

In the 2 decades since its discovery, IL-17A has become appreciated for mounting robust, protective responses against bacterial and fungal pathogens. When improperly regulated, however, IL-17A can play a profoundly pathogenic role in perpetuating inflammation and has been linked to a wide variety of debilitating diseases. IL-17A is often present in a composite milieu that includes cytokines produced by TH17 cells (i.e., IL-17F, IL-21, IL-22, and IL-26) or associated with other T cell lineages (e.g., IFN-γ). These combinatorial effects add mechanistic complexity and more importantly, contribute differentially to disease outcome. Whereas TH17 cells are among the best-understood cell types that secrete IL-17A, they are frequently neither the earliest nor dominant producers. Indeed, non-TH17 cell sources of IL-17A can dramatically alter the course and severity of inflammatory episodes. The dissection of the temporal regulation of TH17-associated cytokines and the resulting net signaling outcomes will be critical toward understanding the increasingly intricate role of IL-17A and TH17-associated cytokines in disease, informing our therapeutic decisions. Herein, we discuss important non-TH17 cell sources of IL-17A and other TH17-associated cytokines relevant to inflammatory events in mucosal tissues.

Th17 differentiation and their pro-inflammation function

CD4(+) T helper cells are classical but constantly reinterpreted T-cell subset, playing critical roles in a diverse range of inflammatory responses or diseases. Depending on the cytokines they release and the immune responses they mediate, CD4(+) T cells are classically divided into two major cell populations: Th1 and Th2 cells. However, recent studies challenged this Th1/Th2 paradigm by discovering several T-helper cell subsets with specific differentiation program and functions, including Th17 cells, Treg cells, and Tfh cells. In this chapter, we summarize the current understanding and recent progresses on the Th17 lineage differentiation and its effector impacts on variety of inflammatory responses or disease pathogenesis.

Protective effect of a germline, IL-17-neutralizing antibody in murine models of autoimmune inflammatory disease

Monoclonal antibodies (mAbs) inhibiting cytokines have recently emerged as new drug modalities for the treatment of chronic inflammatory diseases. Interleukin-17 (IL-17) is a T-cell-derived central mediator of autoimmunity. Immunization with Qβ-IL-17, a virus-like particle based vaccine, has been shown to produce autoantibodies in mice and was effective in ameliorating disease symptoms in animal models of autoimmunity. To characterize autoantibodies induced by vaccination at the molecular level, we generated mouse mAbs specific for IL-17 and compared them to germline Ig sequences. The variable regions of a selected hypermutated high-affinity anti-IL-17 antibody differed in only three amino acid residues compared to the likely germline progenitor. An antibody, which was backmutated to germline, maintained a surprisingly high affinity (0.5 nM). The ability of the parental hypermutated antibody and the derived germline antibody to block inflammation was subsequently tested in murine models of multiple sclerosis (experimental autoimmune encephalomyelitis), arthritis (collagen-induced arthritis), and psoriasis (imiquimod-induced skin inflammation). Both antibodies were able to delay disease onset and significantly reduced disease severity. Thus, the mouse genome unexpectedly encodes for antibodies with the ability to functionally neutralize IL-17 in vivo.

Cytokines in psoriasis

Psoriasis is a common inflammatory skin disease with an incompletely understood etiology. The disease is characterized by red, scaly and well-demarcated skin lesions formed by the hyperproliferation of epidermal keratinocytes. This hyperproliferation is driven by cytokines secreted by activated resident immune cells, an infiltrate of T cells, dendritic cells and cells of the innate immune system, as well as the keratinocytes themselves. Psoriasis has a strong hereditary character and has a complex genetic background. Genome-wide association studies have identified polymorphisms within or near a number of genes encoding cytokines, cytokine receptors or elements of their signal transduction pathways, further implicating these cytokines in the psoriasis pathomechanism. A considerable number of inflammatory cytokines have been shown to be elevated in lesional psoriasis skin, and the serum concentrations of a subset of these also correlate with psoriasis disease severity. The combined effects of the cytokines found in psoriasis lesions likely explain most of the clinical features of psoriasis, such as the hyperproliferation of keratinocytes, increased neovascularization and skin inflammation. Thus, understanding which cytokines play a pivotal role in the disease process can suggest potential therapeutic targets. A number of cytokines have been therapeutically targeted with success, revolutionizing treatment of this disease. Here we review a number of key cytokines implicated in the pathogenesis of psoriasis.