Molecular characterization of human skin response to diphencyprone at peak and resolution phases: therapeutic insights

Diphencyprone reduces the CD8+ lymphocytes and IL-4 and enhences IgG2a/IgG1 ratio in pathogenicity of acute leishmania major infection in BALB/c mice

BACKGROUND

The exact role of different immune cells and cytokines in control or promotion of intracellular growth of leishmania has still remained a controversial topic. The aim of the present study was to study effects of cellular changes and relevant cytokines in cell mediated immunity by diphencyprone (DCP) in pathogenicity of acute L.major infection in BALB/c mice.

METHODS

45 healthy female BALB/c mice were injected with L. major promastigotes under the base of tail. The mice were randomly divided to three groups of 15 mice: (1) control group without any treatment. (2) acetone group: Acetone was applied topically on the cutaneous lesions weekly and (3) DCP group: DCP was applied topically on the cutaneous lesions with increasing concentrations to induce local allergy. The mice were followed by the end of eighth week, and then macroscopic changes, histopathology, immunology studies, and organ parasite burden were determined.

RESULTS

In DCP group, in comparison to other groups the ulcer size and parasite burden in ulcer site and spleen increased, significantly. There was a deep lymphohistiocytic infiltration in the ulcer site. Total IgG, IgG1, and IgG2a levels as well as IgG2a/IgG1 ratio and intracellular IFN-gamma in CD8+ lymphocytes were significantly higher. IL4 and T CD8+ lymphocytes were significantly lower in DCP group. The IgG2a/IgG1 ratio was more than 1 in all groups.

CONCLUSION

Our findings demonstrated that DCP reduced the CD8+ lymphocytes and IL-4 production. In spite of increased IgG2a/IgG1 ratio, the parasite burden and inflammation severity increased in infected mice. The results can show the pivotal role of CD8+ lymphocytes in conjunction with Th1 lymphocytes in the control of acute leishmania infection in mice.

Delayed type hypersensitivity reactions to various allergens may differently model inflammatory skin diseases

BACKGROUND

Treatment of inflammatory skin diseases, including atopic dermatitis (AD) and psoriasis, is undergoing transformative changes, highlighting the need to develop experimental models of skin inflammation in humans to predict treatment responses.

METHODS

We topically or intradermally administered four common sensitizers (dust mite (DM), diphencyprone (DPCP), nickel (Ni), and purified protein derivative (PPD)) to the backs of 40 healthy patients and the skin hypersensitivity response was biopsied and evaluated using immunohistochemistry, RNA-seq, and RT-PCR.

RESULTS

All agents induced strong increases in cellular infiltrates (T-cells and dendritic cells) as compared to untreated skin (p < .05), with variable T helper polarization. Overall, DPCP induced the strongest immune responses across all pathways, including innate immunity (IL-1α, IL-8), Th1 (IFNγ, CXCL10), Th2 (IL-5, CCL11), and Th17 (CAMP/LL37) products, as well as the highest regulatory tone (FOXP3, IL-34, IL-37) (FDR <0.01). Nickel induced Th17 (IL-17A), Th1 (CXCL10) and Th2 (IL-4R) immune responses to a lesser extent than DPCP (p < .05). PPD induced predominantly Th1 (IFNγ, CXCL10, STAT1) and Th17 inflammation (IL-17A) (p < .05). DM induced modulation of Th2 (IL-13, CCL17, CCL18), Th22 (IL-22), and Th17/Th22 (S100A7/9/12) pathways (p < .05). Barrier defects that characterize both AD and psoriasis were best modeled by DPCP and Ni, followed by PPD, including downregulation of terminal differentiation (FLG, FLG2, LOR, LCEs), tight junction (CLDN1/CLDN8), and lipid metabolism (FA2H, FABP7)-related markers.

CONCLUSION

Our data imply that DPCP induced the strongest immune response across all pathways, and barrier defects characteristic of AD and psoriasis.

Unique protein signatures evolve during the course of a delayed-type hypersensitivity reaction in human skin

Diphencyprone (DPCP) is a hapten that causes a delayed-type hypersensitivity reaction when applied topically. It has clinical uses in the treatment of various conditions such as melanoma metastases, warts, and alopecia areata, but the mechanisms are currently not well understood in humans. To further characterize the immunologic effects of DPCP, the authors performed a proteomic analysis of normal skin of eight healthy volunteers following a single application of DPCP and compared them with placebo-treated skin from the same volunteers. A total of 96 proteins were examined using the Olink immuno-oncology panel at 3 days (peak response), 14 days (partially resolved response), and 120 days (completely resolved response). Our analysis revealed significant upregulation of markers of immune cell activation (interleukin [IL] 8), vascular and tissue remodeling (matrix metallopeptidase 12 [MMP12], nitric oxide synthase 3 [NOS3]), antineoplastic markers (granzyme B [GZMB]), and the Th1 axis (interferon gamma [IFNG], chemokine (C-X-C motif) ligand [CXCL] 9, CXCL10, CXCL11) at days 3 and 14 compared with placebo (p < 0.05). In addition, several negative regulators of immune function such as programmed cell death 1 (PD1), programmed cell death ligand 1 (PDL1) (p < 0.001), and lymphocyte activation gene 3 (LAG3) (p < 0.05) were significantly upregulated at days 3 and 14. This induction of negative regulators may explain the seemingly paradoxical therapeutic benefits of DPCP in autoimmune conditions such as alopecia areata. The current analysis also indicated IL-4 upregulation only at day 3, followed by IL-12 upregulation only at day 14, suggesting a transient Th2 response followed by Th1 polarization. Overall, these data suggest a complex and evolving immunological delayed-type hypersensitivity response to a single application of DPCP over time. Future proteomic studies of samples from patients with melanoma metastases, warts, and alopecia areata treated long term with DPCP are needed to further evaluate its pharmacologic mechanisms.

A systematic review on the treatment of pediatric severe alopecia areata by topical immunotherapy or Anthralin (contact sensitization) or low-level light/laser therapy (LLLT): focus on efficacy, safety, treatment duration, recurrence, and follow-up based on clinical studies

INTRODUCTION

Alopecia areata (AA) in its extensive and severe forms is treatment-challenging, especially in pediatrics.

METHOD

A PRISMA-compliant systematic review of seven electronic databases was searched by the terms "alopecia areata," "pediatric," "topical immunotherapy," "Anthralin," and "light therapy" from inception until March 2021. All the alternative names of the disease and therapies have been included in the search terms. 790 articles went to title abstract review by two independent reviewers. In the subsequent level, a review of the full text of studies was conducted.

RESULTS

Finally, 10 relevant articles in terms of content structure, subject coverage, and purpose, were selected for further review. The highest percentages of complete hair regrowth were 79.6% and 63.61% by SADBE (topical immunotherapy) and laser therapy. By Anthralin (contact sensitization), the complete response rate was below 50% (between 30 and 35%). Regarding average response, the most effective methods were local immunotherapy (with an average effectiveness of 53.8%), laser therapy (52.55%), and the use of Anthralin-induced contact dermatitis (30.86%), respectively. However, recurrence rate-after treatment with induced contact dermatitis by topical medications like Anthralin (contact sensitization)-was lower (mean 43.53%) in comparison with local immunotherapy (57%). In topical immunotherapy, light base therapy, and contact sensitization, the highest percentage of complete hair regrowth and the average response rate were (63.61% and 52.55%), (79.6% and 53.8%) and (32% and 30.8%), respectively. These methods are considered safe in children.

CONCLUSION

A high and more than 50% efficacy in hair regrowth could be expected by topical immunotherapy and light/laser therapy method. No serious side effects have been observed by these methods that are well tolerated in children. Therefore, a combination of local immunotherapy and light/laser therapy could be suggested for the treatment of extensive AA in children. The use of Anthralin could be associated with a lower but more durable response. These points are important for patient selection in individualized situations.

Application of Topical Immunotherapy in the Treatment of Alopecia Areata: A Review and Update

Treatment of extensive or recalcitrant alopecia areata (AA) is a major clinical challenge. Even after thorough investigation of several medications, its treatment outcomes have remained unsatisfactory. While there is no US Food and Drug Administration-approved medication for AA yet, topical immunotherapy has been a well-documented treatment option. Dinitrochlorobenzene, squaric acid dibutylester, and diphenylcyclopropenone are three substances that have demonstrated efficacy in the treatment of extensive or recalcitrant AA. Despite being commonly used, the mechanism underlying topical immunotherapy is not well-elucidated and a wide range of clinical efficacies have been reported in the literature. The aim of this review was to summarize and update the pharmacology, mechanism of action, therapeutic efficacy, and tolerability of topical immunotherapy in the treatment of AA.

Quantitative and Spatial Analysis of CD8+/PD-1 Tumor-Infiltrating Lymphocytes as a Predictive Biomarker for Clinical Response of Melanoma In-Transit Metastases to Topical Immunotherapy

Background

Melanoma in-transit metastases (ITMs) are a challenge to treat and associated with systemic disease and poor prognosis. Topical diphencyprone (DPCP), a potent contact sensitizer, is an established treatment for melanoma ITMs. This exploratory study investigated the utility of BRAF mutation status, CD8, PD-1, PD-L1, and TILs distribution as biomarkers for response of ITMs to topical immunotherapy (DPCP).

Methods

The ITM deposits of 40 patients treated with DPCP were subjected to biomarker analysis for BRAF status, CD8 and PD-1 expression on tumor-infiltrating lymphocytes (TILs), and tumor PD-L1 expression. Response to DPCP and overall survival (OS) were compared by biomarker status.

Results

After 12 weeks, 10 patients (25%) had a complete response, 12 patients (30%) had a partial response, and 18 patients (45%) had no response. No significant association was found between any individual biomarker and response to DPCP or OS. The BRAF mutation rate was 25% (10/40). All the patients with a complete response had BRAF wild-type tumor. Peritumoral CD8+ T-cells were associated with complete response (P = 0.041). Both CD8+ and PD-1 expressions were highly correlated (P < 0.0001), and the highest levels of PD-1 expression were detected at the peritumoral interface (P = 0.0004). Only two cases were PD-L1-positive, and both had a complete response to DPCP (P = 0.043).

Conclusion

Patients who have BRAF wild-type tumor are more likely to experience a complete response to DPCP. Peritumoral TILs and PD-1 expressions may predict a better response to DPCP. Expression of PD-L1 may be associated with a complete response to DPCP. A larger prospective study is required.

Cross-sectional study of blood biomarkers of patients with moderate to severe alopecia areata reveals systemic immune and cardiovascular biomarker dysregulation

BACKGROUND

Although there is increased understanding of the alopecia areata (AA) pathogenesis based on studies in scalp tissues, little is known about its systemic profile.

OBJECTIVE

To evaluate the blood proteomic signature of AA and determine biomarkers associated with increased disease severity.

METHODS

In a cross-sectional study, we assessed 350 inflammatory and cardiovascular proteins using OLINK high-throughput proteomics in patients with moderate to severe AA (n = 35), as compared with healthy individuals (n = 36), patients with moderate to severe psoriasis (n = 19), and those with atopic dermatitis (n = 49).

RESULTS

Seventy-four proteins were significantly differentially expressed between AA and control individuals (false discovery rate, <.05) including innate immunity (interleukin [IL] 6/IL-8), T helper (Th) type 1 (interferon [IFN] γ/CXCL9/CXCL10/CXCL11), Th2 (CCL13/CCL17/CCL7), Th17 (CCL20/PI3/S100A12), and cardiovascular-risk proteins (OLR1/OSM/MPO/PRTN3). Eighty-six biomarkers correlated with AA clinical severity (P < .05), including Th1/Th2, and cardiovascular/atherosclerosis-related proteins, including SELP/PGLYRP1/MPO/IL-18/OSM (P < .05). Patients with AA totalis/universalis showed the highest systemic inflammatory tone, including cardiovascular risk biomarkers, compared to control individuals and even to patients with atopic dermatitis and those with psoriasis. The AA profile showed some Th1/Th2 differences in the setting of concomitant atopy.

LIMITATIONS

Our analysis was limited to 350 proteins.

CONCLUSION

This study defined the abnormalities of moderate to severe AA and associated circulatory biomarkers. It shows that AA has systemic immune, cardiovascular, and atherosclerosis biomarker dysregulation, suggesting the need for systemic treatment approaches.

Human "TH9" cells are a subpopulation of PPAR-γ+ TH2 cells

Although T_H1, T_H2, and T_H17 cells are well-defined T_H cell lineages in humans, it remains debated whether IL-9-producing T_H cells represent a bona fide "T_H9" lineage. Our understanding of the cellular characteristics and functions of IL-9-producing T_H cells in humans is still nascent. Here, we report that human IL-9-producing T_H cells express the chemokine receptors CCR4 and CCR8, produce high levels of IL-5 and IL-13, and express T_H2 lineage-associated transcription factors. In these cells, IL-9 production is activation dependent, transient, and accompanied by down-regulation of T_H2 cytokines, leading to an apparent "T_H9" phenotype. IL-9⁺ T_H2 cells can be distinguished from "conventional" T_H2 cells based on their expression of the transcription factor PPAR-γ. Accordingly, PPAR-γ is induced in naïve T_H cells by priming with IL-4 and TGF-β ("T_H9" priming) and is required for IL-9 production. In line with their identity as early activated T_H2 cells, IL-9⁺ T_H2 cells are found in acute allergic skin inflammation in humans. We propose that IL-9-producing T_H cells are a phenotypically and functionally distinct subpopulation of T_H2 cells that depend on PPAR-γ for full effector functions.

Topical and intralesional therapies for in-transitmelanoma

This report surveys the role of topical and intralesional agents in the management of in-transit melanoma. The extent and progression of in-transit disease is highly variable and many patients can have a protracted period of locoregional control. These agents are useful in the management of patients who have progressed beyond local surgical excision in whom more aggressive therapies, such as isolated limb infusion or use of talimogene laherparepvec, are not appropriate or have failed. In general, these agents are modestly effective and associated with frequent but only minor toxicity. As the mechanism of action of many of these agents includes initiation of a local immune response, combinations with immune checkpoint inhibitors are currently being explored.

Immunomodulatory effects of topical diphencyprone for the treatment of acute urban cutaneous leishmaniasis

BACKGROUND AND OBJECTIVE

Efficacious and safe treatments are lacking for cutaneous leishmaniasis (CL). This study investigates the efficacy of adding diphencyprone immunotherapy to conventional meglumine antimoniate (MA) treatment for acute urban CL.

METHODS

This randomized controlled pilot study included 46 patients with acute CL. They were randomly allocated to receive either combination of diphencyprone immunotherapy with intralesional MA (intervention; N = 23) or intralesional MA alone (control; N = 23) weekly. The size and duration of lesions were measured at the baseline and after that at 4th, 8th, 12th, and 24th weeks. Data were analyzed in SPSS and p < .05 was considered significant.

RESULTS

The groups showed no significant difference in duration of lesions, but number of injections was significantly higher in the control group compared with the intervention group (p < .001). Size and induration of lesions was significantly reduced in both groups during the course of study (p < .001). The intervention group showed significantly lower induration of lesions in 4th, 8th, and 12th week compared with controls (p < .05).

CONCLUSION

Combination of diphencyprone with MA resulted in earlier resolution of acute CL lesions with a relatively acceptable rate of adverse effects, compared with intralesional MA alone.

Recent advances in localized immunotherapy of skin cancers

Skin cancer is the most frequent malignancy in humans. The immune system has long been known to have an important role in defeating cancer. Immunotherapy, which includes various strategies to enhance tumor immunity, currently represents an exciting option for the treatment of skin cancers. Local immunotherapy is a promising therapeutic approach and may improve response rates without inducing systemic toxicity. Here, we review the main localized immunotherapies for the management of skin cancer with a special focus on advanced melanoma, nonmelanoma skin cancer and primary cutaneous lymphoma.

Tissue Resident CD8 Memory T Cell Responses in Cancer and Autoimmunity

Resident memory (T_RM) cells are a distinct tissue-localized T cell lineage that is crucial for protective immunity in peripheral tissues. While a great deal of effort has focused on defining their role in immunity to infections, studies now reveal T_RM cells as a vital component of the host immune response to cancer. Characterized by cell-surface molecules including CD103, CD69, and CD49a, T_RM-like tumor-infiltrating lymphocytes (TILs) can be found in a wide range of human cancers, where they portend improved prognosis. Recent studies in mouse tumor models have shown that T_RM cells are induced by cancer vaccines delivered in peripheral tissue sites, or by the depletion of regulatory T cells. Such tumor-specific T_RM cells are recognized as both necessary and sufficient for long-lived protection against tumors in peripheral tissue locations. T_RM responses against tumor/self-antigens can concurrently result in the development of pathogenic T_RM responses to self, with a growing number of autoimmune diseases and inflammatory pathologies being attributed to T_RM responses. This review will recount the path to discovering the importance of resident memory CD8 T cells as they pertain to cancer immunity. In addition to highlighting key studies that directly implicate T_RM cells in anti-tumor immunity, we will highlight earlier work that implicitly suggested their importance. Informed by studies in infectious disease models, and instructed by a clear role for T_RM cells in autoimmunity, we will discuss strategies for therapeutically promoting T_RM responses in settings where they don't naturally occur.

Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan

Epidemiological evidence indicates that regular physical activity and/or frequent structured exercise reduces the incidence of many chronic diseases in older age, including communicable diseases such as viral and bacterial infections, as well as non-communicable diseases such as cancer and chronic inflammatory disorders. Despite the apparent health benefits achieved by leading an active lifestyle, which imply that regular physical activity and frequent exercise enhance immune competency and regulation, the effect of a single bout of exercise on immune function remains a controversial topic. Indeed, to this day, it is perceived by many that a vigorous bout of exercise can temporarily suppress immune function. In the first part of this review, we deconstruct the key pillars which lay the foundation to this theory-referred to as the "open window" hypothesis-and highlight that: (i) limited reliable evidence exists to support the claim that vigorous exercise heightens risk of opportunistic infections; (ii) purported changes to mucosal immunity, namely salivary IgA levels, after exercise do not signpost a period of immune suppression; and (iii) the dramatic reductions to lymphocyte numbers and function 1-2 h after exercise reflects a transient and time-dependent redistribution of immune cells to peripheral tissues, resulting in a heightened state of immune surveillance and immune regulation, as opposed to immune suppression. In the second part of this review, we provide evidence that frequent exercise enhances-rather than suppresses-immune competency, and highlight key findings from human vaccination studies which show heightened responses to bacterial and viral antigens following bouts of exercise. Finally, in the third part of this review, we highlight that regular physical activity and frequent exercise might limit or delay aging of the immune system, providing further evidence that exercise is beneficial for immunological health. In summary, the over-arching aim of this review is to rebalance opinion over the perceived relationships between exercise and immune function. We emphasize that it is a misconception to label any form of acute exercise as immunosuppressive, and, instead, exercise most likely improves immune competency across the lifespan.

Topical Immunotherapy of Alopecia Areata: A Large Retrospective Study

INTRODUCTION

Topical immunotherapy is frequently used in the treatment of alopecia areata (AA) although few studies report long-term follow-up. Our goals were to determine the efficacy and the prognostic factors of topical immunotherapy in a large cohort of patients with AA treated in the departments of Dermatology and Venereology of Bergamo, Como and Pavia, from 1978 to January 2016.

METHODS

A total of 252 patients with AA were evaluated retrospectively.

RESULTS

All our patients developed an allergic reaction to a 2% solution of dinitrochlorobenzene (DNCB) or squaric acid dibutylester (SADBE) or diphenylcyclopropenone (DPCP). No patients discontinued therapy because of side effects. In total 112 patients (44.05%, p < 0.001) had a good response. Statistical analysis revealed that the main prognostic factors influencing the clinical results were the severity of hair loss at the beginning of therapy, the duration of AA, a history of atopy (particularly eczema), and the early development of sensitization to the three sensitizers.

CONCLUSION

Topical immunotherapy in patients with AA is quite effective, mostly well tolerated, and provides prolonged therapeutic benefits.

Epidermal cornification is preceded by the expression of a keratinocyte-specific set of pyroptosis-related genes

The homeostasis of the epidermis depends on keratinocyte differentiation and cornification, a mode of programmed cell death that does not elicit inflammation. Here, we report that cornification is associated with the expression of specific genes that control multiple steps of pyroptosis, another form of cell death that involves the processing and release of interleukin-1 family (IL1F) cytokines. Expression levels of pro-inflammatory IL1A and IL1B and of the pyroptotic pore-forming gasdermin (GSDM) D were downregulated during terminal differentiation of human keratinocytes in vitro. By contrast, negative regulators of IL-1 processing, including NLR family pyrin domain containing 10 (NLRP10) and pyrin domain-containing 1 (PYDC1), the anti-inflammatory IL1F members IL-37 (IL1F7) and IL-38 (IL1F10), and GSDMA, were strongly induced in differentiated keratinocytes. In human tissues, these keratinocyte differentiation-associated genes are expressed in the skin at higher levels than in any other organ, and mammalian species, that have lost the epidermal cornification program during evolution, i.e. whales and dolphins, lack homologs of these genes. Together, our results suggest that human epidermal cornification is accompanied by a tight control of pyroptosis and warrant further studies of potential defects in the balance between cornification and pyroptosis in skin pathologies.

TH9 cells in skin disorders

Interleukin 9 secreting T_H9 cells have been proposed as the latest addition to the family of T helper cell subsets. While a growing body of evidence from animal models points to important roles for these cells in allergic inflammation of the lung, autoinflammation of the gastrointestinal tract, and tumor immunity, their role in skin immunity and skin immunopathology remains poorly defined. Interestingly, studies of T helper cells from healthy humans suggest that T_H9 cells are predominantly skin-homing and skin-resident and that they are involved in protection against extracellular pathogens. Thus, T_H9 cells have entered the stage as potential mediators of cutaneous pathology. However, under which conditions and by which mechanisms these cells contribute to skin immunity and disease still has to be investigated. Here, we review our current understanding of T_H9 cells as skin-tropic T helper cells and their involvement in skin pathology. Further, we discuss open questions with regard to the intricate nature of interleukin 9 producing T helper cells.

Biomarkers of alopecia areata disease activity and response to corticosteroid treatment

Alopecia areata (AA) is a common inflammatory disease targeting the anagen-stage hair follicle. Different cytokines have been implicated in the disease profile, but their pathogenic role is not yet fully determined. We studied biopsies of pretreatment lesional and non-lesional (NL) scalp and post-treatment (intra-lesional steroid injection) lesional scalp of 6 patchy patients with AA using immunohistochemistry and gene expression analysis. Immunohistochemistry showed increases in CD3(+) , CD8(+) T cells, CD11c(+) dendritic cells and CD1a(+) Langerhans cells within and around hair follicles of pretreatment lesional scalp, which decreased upon treatment. qRT-PCR showed in pretreatment lesional scalp (compared to NL) significant increases (P < 0.05) in expression of inflammatory markers (IL-2, IL-2RA, JAK3, IL-15), Th1 (CXCL10 and CXCL9), Th2 (IL-13, CCL17 and CCL18), IL-12/IL-23p40 and IL-32. Among these, we observed significant downregulation with treatment in IL-12/IL-23p40, CCL18 and IL-32. We also observed significant downregulation of several hair keratins in lesional scalp, with significant upregulation of KRT35, KRT75 and KRT86 in post-treatment lesional scalp. This study shows concurrent activation of Th1 and Th2 immune axes as well as IL-23 and IL-32 cytokine pathways in lesional AA scalp and defined a series of response biomarkers to corticosteroid injection. Clinical trials with selective antagonists coupled with cytokine-pathway biomarkers will be necessary to further dissect pathogenic immunity.

The tryptophan metabolism enzyme L-kynureninase is a novel inflammatory factor in psoriasis and other inflammatory diseases

BACKGROUND

Many human diseases arise from or have pathogenic contributions from a dysregulated immune response. One pathway with immunomodulatory ability is the tryptophan metabolism pathway, which promotes immune suppression through the enzyme indoleamine 2,3-dioxygenase (IDO) and subsequent production of kynurenine. However, in patients with chronic inflammatory skin disease, such as psoriasis and atopic dermatitis (AD), another tryptophan metabolism enzyme downstream of IDO, L-kynureninase (KYNU), is heavily upregulated. The role of KYNU has not been explored in patients with these skin diseases or in general human immunology.

OBJECTIVE

We sought to explore the expression and potential immunologic function of the tryptophan metabolism enzyme KYNU in inflammatory skin disease and its potential contribution to general human immunology.

METHODS

Psoriatic skin biopsy specimens, as well as normal human skin, blood, and primary cells, were used to investigate the immunologic role of KYNU and tryptophan metabolites.

RESULTS

Here we show that KYNU(+) cells, predominantly of myeloid origin, infiltrate psoriatic lesional skin. KYNU expression positively correlates with disease severity and inflammation and is reduced on successful treatment of psoriasis or AD. Tryptophan metabolites downstream of KYNU upregulate several cytokines, chemokines, and cell adhesions. By mining data on several human diseases, we found that in patients with cancer, IDO is preferentially upregulated compared with KYNU, whereas in patients with inflammatory diseases, such as AD, KYNU is preferentially upregulated compared with IDO.

CONCLUSION

Our results suggest that tryptophan metabolism might dichotomously modulate immune responses, with KYNU as a switch between immunosuppressive versus inflammatory outcomes. Although tryptophan metabolism is increased in many human diseases, how tryptophan metabolism is proceeding might qualitatively affect the immune response in patients with that disease.

Diphencyprone Treatment of Alopecia Areata: Postulated Mechanism of Action and Prospects for Therapeutic Synergy with RNA Interference

Diphencyprone (DPCP) is a potent topical sensitizing agent that has been used since the late 1970s by physicians for the treatment of alopecia areata (AA), viral warts (human papillomavirus) and cutaneous metastases of melanoma. Although to date the compound is not approved as a drug by the FDA or EMA, physicians have continued to use DPCP because of its proven effects in these dermatological conditions. The use of the drug has been highly variable because of differences in compounding, and as a result, the literature reports vary widely in the concentrations used for sensitization and challenge treatment with DPCP. The efficacy of DPCP has generally been ascribed to immunological reactions by the host. Inducing inflammation with a contact sensitizer is counterintuitive to treating AA, an autoimmune disorder. We have hypothesized that the body's attempt to downregulate the inflammation caused by the contact sensitizer may also ameliorate AA. Studies using microarray and miRNA profiling may provide information about how DPCP induces inflammation in human skin at different times. Gene targets and microRNAs identified through these data may be modulated by an RNA interference approach to enhance DPCP efficacy and response rates. In addition, this approach may result in the discovery and development of drugs that are more potent and selective for the treatment of AA.

Unique microRNAs appear at different times during the course of a delayed-type hypersensitivity reaction in human skin

Diphencyprone (DPCP) is a hapten that induces delayed-type hypersensitivity (DTH) reactions. MicroRNAs (miRNAs) are short non-coding RNAs that negatively regulate gene expression and have been implicated in various inflammatory skin diseases, but their role in DTH reactions is not well understood. We generated global miRNA expression profiles (using next-generation sequencing) of DPCP reactions in skin of seven healthy volunteers at 3, 14 and 120 days after challenge. Compared to placebo-treated sites, DPCP-challenged skin at 3 days (peak inflammation) had 127 miRNAs significantly deregulated. At 14 days (during resolution of inflammation), 43 miRNAs were deregulated and, at 120 days (when inflammation had completely resolved), six miRNAs were upregulated. While some miRNAs have been observed in psoriasis or atopic dermatitis, most of the deregulated miRNAs have not yet been studied in the context of skin biology or immunology. Across the three time points studied, many but not all miRNAs were uniquely expressed. As various miRNAs may influence T cell activation, this may indicate that the miRNAs exclusively expressed at different time points function to promote or resolve skin inflammation, and therefore, may inform on the paradoxical ability of DPCP to treat both autoimmune conditions (alopecia areata) and conditions of ineffective immunity (melanoma).

Psoriasis is characterized by deficient negative immune regulation compared to transient delayed-type hypersensitivity reactions

Diphencyprone (DPCP) is a hapten that causes delayed-type hypersensitivity (DTH) reactions in human skin, and is used as a topical therapeutic for alopecia areata, warts, and cutaneous melanoma metastases.  We examined peak DTH reactions induced by DPCP (3 days post-challenge) by comprehensive gene expression and histological analysis.  To better understand how these DTH reactions naturally resolve, we compared our DPCP biopsies to those from patients with psoriasis vulgaris, a chronic inflammatory disease that does not resolve.  By both microarray and qRT-PCR, we found that psoriasis lesional skin has significantly lower expression of many negative immune regulators compared to peak DPCP reactions.  These regulators include: interleukin-10, cytotoxic T lymphocyte-associated 4 (CTLA4), programmed cell death 1 (PD1), programmed cell death 1 ligand 1 (PDL1), programmed cell death 1 ligand 2 (PDL2), and indoleamine 2,3-dioxygenase (IDO1).  Their decreased expression was confirmed at the protein level by immunohistochemistry.  To more completely determine the balance of positive vs. negative immune regulators in both DPCP reactions and psoriasis, we developed one comprehensive gene list for positive regulatory (inflammatory) genes, and another for negative regulatory (immunosuppressive) genes, through Gene Ontology terms and literature review.  With this approach, we found that DPCP reactions have a higher ratio of negative to positive regulatory genes (both in terms of quantity and expression levels) than psoriasis lesional skin.  These data suggest that the disease chronicity that distinguishes psoriasis from transient DTH reactions may be related to absence of negative immune regulatory pathways, and induction of these is therefore of therapeutic interest.  Further study of these negative regulatory mechanisms that are present in DPCP reactions, but not in psoriasis, could reveal novel players in the pathogenesis of chronic inflammation.  The DPCP system used here thus provides a tractable model for primary discovery of pathways potentially involved in immune regulation in peripheral tissues.

Comparative genomic profiling of synovium versus skin lesions in psoriatic arthritis

Objective

To our knowledge, there is no broad genomic analysis comparing skin and synovium in psoriatic arthritis (PsA). Also, there is little understanding of the relative levels of cytokines and chemokines in skin and synovium. The purpose of this study was to better define inflammatory pathways in paired lesional skin and affected synovial tissue in patients with PsA.

Methods

We conducted a comprehensive analysis of cytokine and chemokine activation and genes representative of the inflammatory processes in PsA. Paired PsA synovial tissue and skin samples were obtained from 12 patients on the same day. Gene expression studies were performed using Affymetrix HGU133 Plus 2.0 arrays. Confirmatory quantitative real-time polymerase chain reaction (PCR) was performed on selected transcripts. Cell populations were assessed by immunohistochemistry and immunofluorescence.

Results

Globally, gene expression in PsA synovium was more closely related to gene expression in PsA skin than to gene expression in synovium in other forms of arthritis. However, PsA gene expression patterns in skin and synovium were clearly distinct, showing a stronger interleukin-17 (IL-17) gene signature in skin than in synovium and more equivalent tumor necrosis factor (TNF) and interferon-γ gene signatures in both tissues. These results were confirmed with real-time PCR.

Conclusion

This is the first comprehensive molecular comparison of paired lesional skin and affected synovial tissue samples in PsA. Our results support clinical trial data showing that PsA skin and joint disease are similarly responsive to TNF antagonists, while IL-17 antagonists have better results in PsA skin than in PsA joints. Genes selectively expressed in PsA synovium might direct future therapies for PsA.

Common clonal origin of central and resident memory T cells following skin immunization

Central memory T (TCM) cells in lymph nodes (LNs) and resident memory T (TRM) cells in peripheral tissues have distinct roles in protective immunity. Both are generated after primary infections, but their clonal origins have been unclear. To address this question, we immunized mice through the skin with a protein antigen, a chemical hapten, or a non-replicating poxvirus. We then analyzed antigen-activated T cells from different tissues using high-throughput sequencing (HTS) of the gene encoding the T cell receptor (TCR) β-chain (Trb, also known as Tcrb) using CDR3 sequences to simultaneously track thousands of unique T cells. For every abundant TRM cell clone generated in the skin, an abundant TCM cell clone bearing the identical TCR was present in the LNs. Thus, antigen-reactive skin TRM and LN TCM cell clones were derived from a common naive T cell precursor after skin immunization, generating overlapping TCR repertoires. Although they bore the same TCR, TRM cells mediated rapid contact hypersensitivity responses, whereas TCM cells mediated delayed and attenuated responses. Studies in human subjects confirmed the generation of skin TRM cells in allergic contact dermatitis. Thus, immunization through skin simultaneously generates skin TRM and LN TCM cells in similar numbers from the same naive T cells.

Suppression of antigen-specific adaptive immunity by IL-37 via induction of tolerogenic dendritic cells

IL-1 family member IL-37 limits innate inflammation in models of colitis and LPS-induced shock, but a role in adaptive immunity remains unknown. Here, we studied mice expressing human IL-37b isoform (IL-37tg) subjected to skin contact hypersensitivity (CHS) to dinitrofluorobenzene. CHS challenge to the hapten was significantly decreased in IL-37tg mice compared with wild-type (WT) mice (-61%; P < 0.001 at 48 h). Skin dendritic cells (DCs) were present and migrated to lymph nodes after antigen uptake in IL-37tg mice. When hapten-sensitized DCs were adoptively transferred to WT mice, antigen challenge was greatly impaired in mice receiving DCs from IL-37tg mice compared with those receiving DCs from WT mice (-60%; P < 0.01 at 48 h). In DCs isolated from IL-37tg mice, LPS-induced increase of MHC II and costimulatory molecule CD40 was reduced by 51 and 31%, respectively. In these DCs, release of IL-1β, IL-6, and IL-12 was reduced whereas IL-10 secretion increased (37%). Consistent with these findings, DCs from IL-37tg mice exhibited a lower ability to stimulate syngeneic and allogeneic naive T cells as well as antigen-specific T cells and displayed enhanced induction of T regulatory (Treg) cells (86%; P < 0.001) in vitro. Histological analysis of CHS skin in mice receiving hapten-sensitized DCs from IL-37tg mice revealed a marked reduction in CD8(+) T cells (-74%) but an increase in Treg cells (2.6-fold). Together, these findings reveal that DCs expressing IL-37 are tolerogenic, thereby impairing activation of effector T-cell responses and inducing Treg cells. IL-37 thus emerges as an inhibitor of adaptive immunity.