Project description:We found that keratinocytes (KCs) (from healthy subjects) stimulated with nickel were characterized by a specific miRNA signature that were different from vehicle-stimulated KCs.
Project description:We found that peripheral blood mononuclear cells (PBMCs) (from subjects with allergy to nickel) stimulated with nickel were characterized by a specific miRNA signature that were different from vehicle-stimulated PBMCs.
Project description:Our findings demonstrate that nickel-challenged skin in subjects with allergy to nickel is characterized by a specific miRNA signature compared to vehicle-challenged skin. In addition, we found that miRNA expression changes are different in allergic contact dermatitis (ACD to nickel) compared to irritant contact dermatitis (ICD).
Project description:The cytokine IL-9, derived primarily from T-helper 9 (Th9) lymphocytes, promotes expansion of the Th2 subset and is implicated in the mechanisms of allergic asthma. We hypothesize that IL-9 also has a role in human allergic contact dermatitis (ACD). To investigate this hypothesis, skin biopsy specimens of positive patch-test sites from non-atopic patients were assayed using quantitative PCR and immunohistochemistry. The cytokines IFN-γ, IL-4, IL-17A, IL-9, and PU.1, a Th9 associated transcription factor, were elevated when compared with paired normal skin. Immunohistochemistry on ACD skin biopsies identified PU.1+ CD3+ and PU.1+ CD4+ cells, consistent with Th9 lymphocytes, in the inflammatory infiltrate. Peripheral blood mononuclear cells from nickel-allergic patients, but not nonallergic controls, show significant IL-9 production in response to nickel. Blocking studies with mAbs to HLA-DR (but not HLA-A, -B, -C) or chloroquine significantly reduced this nickel-specific IL-9 production. In addition, blockade of IL-9 or IL-4 enhanced allergen-specific IFN-γ production. A contact hypersensitivity model using IL-9(-/-) mice shows enhanced Th1 lymphocyte immune responses, when compared with wild-type mice, consistent with our human in vitro data. This study demonstrates that IL-9, through its direct effects on Th1 and ability to promote IL-4 secretion, has a regulatory role for Th1 lymphocytes in ACD.
Project description:Allergic contact dermatitis (ACD) is well recognized as an adverse event associated with implantable medical devices that contain allergenic materials like nickel; however, other cutaneous consequences of chronic exposure to allergens in implanted devices are not well understood. Here, we present a clinical case of Marjolin's ulcer, an invasive squamous cell carcinoma (SCC) that developed in response to chronic ACD caused by an orthopedic implant. We used a standard murine model of contact hypersensitivity to determine whether chronic ACD promotes skin carcinogenesis. Chronic application of 1-fluoro-2,4-dinitrobenzene (DNFB) to carcinogen-treated skin led to the development of papillomas and aggressive SCC. DNFB-driven chronic ACD was marked by type 2 inflammation, which mediated skin carcinogenesis, as mice unable to mount an inflammatory response were less likely to develop skin tumors. Importantly, we found similar tumor-promoting inflammation surrounding the SCC in our patient. Our findings demonstrate that chronic ACD caused by constant exposure to an allergen can promote tumorigenesis at skin sites with preexisting cancer-initiated cells. Moreover, our results suggest that patients with implantable devices placed in close proximity to the skin should be monitored for ACD and highlight the importance of patch testing prior to the placement of such devices.
Project description:This study aimed to investigate the signaling pathways induced by MI in the skin test of individuals with MI-sensitized ACD, comparing them to healthy controls. Individuals initially testing positive only for MI were recruited at the Contact Dermatitis Clinic at Hospital das Clínicas of São Paulo, re-exposed to MI or saline, and biopsied 48 hours after exposure. Negative controls for the patch test were also exposed to MI and saline for comparison. Histopathological and transcriptomic (RNAseq) analyses identified two groups among the ACD patients: Group A (GA), with more pronounced histopathological features such as spongiosis and microvesicles, and Group B (GB), which showed milder reactions and absence of spongiosis. In GA, a total of 1588 genes were upregulated and 2090 downregulated in response to MI, compared to GB. These differentially expressed genes (DEGs) were associated with inflammation and neurological signaling, such as IL-24, IL-9, IL-13, and NTRK1, while IL-37 and IL-18 were downregulated. Similarly, GA compared to the MI-negative ACD group showed 1169 upregulated and 321 downregulated genes. DEG validation in GA through qPCR confirmed increased expression of NTRK1, IL-9, IL-6, IL-13, and CXCL8, with a reduction in IL-18. Protein analysis of IL-24 and IL-9 revealed higher expression in the dermal layer of GA. These results indicate distinct transcriptional profiles in MI-sensitized individuals, despite positive patch tests in all cases. The observed heterogeneity, not previously described in ACD, points to new potential therapeutic targets, such as IL-9, IL-37, and NTRK1. Furthermore, the study suggests that inflammatory and neurological cytokines, such as IL-9 and NTRK1, play key roles in the pathogenesis of ACD.
Project description:BackgroundLong-term use of most immunosuppressants to treat allergic contact dermatitis (ACD) generates unavoidable severe side effects, warranting discovery or development of new immunosuppressants with good efficacy and low toxicity is urgently needed to treat this condition. Hispidulin, a flavonoid compound that can be delivered topically due to its favorable skin penetrability properties, has recently been reported to possess anti-inflammatory and immunosuppressive properties. However, no studies have investigated the effect of hispidulin on Th1 cell activities in an ACD setting.MethodsA contact hypersensitivity (CHS) mouse model was designed to simulate human ACD. The immunosuppressive effect of hispidulin was investigated via ear thickness, histologic changes (i.e., edema and spongiosis), and interferon-gamma (IFN-γ) gene expression in 1-fluoro-2,4-dinitrobenzene (DNFB)-sensitized mice. Cytotoxicity, total number of CD4+ T cells, and percentage of IFN-γ-producing CD4+ T cells were also investigated in vitro using isolated CD4+ T cells from murine spleens.ResultsTopically applied hispidulin effectively inhibited ear swelling (as measured by reduction in ear thickness), and reduced spongiosis, IFN-γ gene expression, and the number of infiltrated immune cells. The inhibitory effect of hispidulin was observed within 6 h after the challenge, and the observed effects were similar to those effectuated after dexamethasone administration. Hispidulin at a concentration up to 50 μM also suppressed IFN-γ-producing CD4+ T cells in a dose-dependent manner without inducing cell death, and without a change in total frequencies of CD4+ T cells among different concentration groups.ConclusionThe results of this study, therefore, suggest hispidulin as a novel compound for the treatment of ACD via the suppression of IFN-γ production in Th1 cells.
Project description:Allergic contact dermatitis (ACD) is a common inflammatory skin disease with a prevalence of approximately 20% in the European population. ACD is caused by contact allergens that are reactive chemicals able to modify non-immunogenic self-proteins to become immunogenic proteins. The most frequent contact allergens are metals, fragrances, and preservatives. ACD clinically manifests as pruritic eczematous lesions, erythema, local papules, and oedema. ACD is a T cell-mediated disease, involving both CD4+ and CD8+ T cells. In addition, ?? T cells appear to play an important role in the immune response to contact allergens. However, it is debated whether ?? T cells act in a pro- or anti-inflammatory manner. A special subset of ?? T cells, named dendritic epidermal T cells (DETC), is found in the epidermis of mice and it plays an important role in immunosurveillance of the skin. DETC are essential in sensing the contact allergen-induced stressed environment. Thus, allergen-induced activation of DETC is partly mediated by numerous allergen-induced stress proteins expressed on the keratinocytes (KC). Several stress proteins, like mouse UL-16-binding protein-like transcript 1 (Mult-1), histocompatibility 60 (H60) and retinoic acid early inducible-1 (Rae-1) ?-? family in mice and major histocompatibility complex (MHC) class I-chain-related A (MICA) in humans, are upregulated on allergen-exposed KC. Allergen-induced stress proteins expressed on the KC are consequently recognized by NKG2D receptor on DETC. This review focuses on the role of ?? T cells in ACD, with DETC in the spotlight, and on the role of stress proteins in contact allergen-induced activation of DETC.
Project description:BackgroundNickel-induced allergic contact dermatitis (nACD) remains a major occupational skin disorder, significantly impacting the quality of life of suffering patients. Complex cellular compositional changes and associated immunological pathways are partly resolved in humans; thus, the impact of nACD on human skin needs to be further elucidated.MethodsTo decipher involved immunological players and pathways, human skin biopsies were taken at 0, 2, 48, and 96 hours after nickel patch test in six nickel-allergic patients. Gene expression profiles were analyzed via microarray.ResultsLeukocyte deconvolution of nACD-affected skin identified major leukocyte compositional changes at 48 and 96 hours, including natural killer (NK) cells, macrophage polarization, and T-cell immunity. Gene set enrichment analysis mirrored cellular-linked functional pathways enriched over time. NK cell infiltration and cytotoxic pathways were uniquely found in nACD-affected skin compared to sodium lauryl sulfate-induced irritant skin reactions.ConclusionThese results highlight key immunological leukocyte subsets as well as associated pathways in nACD, providing insights into pathophysiology with the potential to unravel novel therapeutic targets.