Contact Hypersensitivity Response Research Articles

Differential effect of Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) on leukocyte infiltration during contact hypersensitivity responses.

Background2′–4′ Dinitrofluorobenzene (DNFB) induced contact hypersensitivity is an established model of contact sensitivity and leukocyte migration. Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) deficient mice were used to examine the role of PECAM-1 in the migration capacity of several different leukocyte populations after primary and secondary application.Resultsγδ T lymphocytes, granulocytes, and Natural Killer cells were most affected by PECAM-1 deficiency at the primary site of application. γδ T lymphocytes, granulocytes, DX5+ Natural Killer cells, and, interestingly, effector CD4+ T lymphocytes were most affected by the loss of PECAM-1 at the secondary site of application.ConclusionsPECAM-1 is used by many leukocyte populations for migration, but there are clearly differential effects on the usage by each subset. Further, the overall kinetics of each population varied between primary and secondary application, with large relative increases in γδ T lymphocytes during the secondary response.

Expression of CD73 slows down migration of skin dendritic cells, affecting the sensitization phase of contact hypersensitivity reactions in mice

BackgroundApplication of haptens to the skin induces release of immune stimulatory ATP into the extracellular space. This “danger” signal can be converted to immunosuppressive adenosine (ADO) by the action of the ectonucleotidases CD39 and CD73, expressed by skin and immune cells. Thus, the expression and regulation of CD73 by skin derived cells may have crucial influence on the outcome of contact hypersensitivity (CHS) reactions. ObjectiveTo investigate the role of CD73 expression during 2,4,6-trinitrochlorobenzene (TNCB) induced CHS reactions. MethodsWild type (wt) and CD73 deficient mice were subjected to TNCB induced CHS. In the different mouse strains the resulting ear swelling reaction was recorded along with a detailed phenotypic analysis of the skin migrating subsets of dendritic cells (DC). ResultsIn CD73 deficient animals the motility of DC was higher as compared to wt animals and in particular after sensitization we found increased migration of Langerin+ DC from skin to draining lymph nodes (LN). In the TNCB model this led to a stronger sensitization as indicated by increased frequency of interferon-γ producing T cells in the LN and an increased ear thickness after challenge. ConclusionCD73 derived ADO production slows down migration of Langerin+ DC from skin to LN. This may be a crucial mechanism to avoid over boarding immune reactions against haptens.

Abstract 2221: Honokiol stimulates immune reactivity in UV-irradiated skin through DNA demethylation-dependent functional activation of dendritic cells in mice

Abstract Solar ultraviolet radiation (UVR), and in particular UVB spectrum (290-320 nm), are considered as a complete carcinogen for cutaneous malignancies. The over-exposure of UVR suppresses the development of allergic contact hypersensitivity (CHS) response in both laboratory animals as well as in humans. CHS response is considered to be a prototypic T-cell mediated immune response. UVR-induced suppression of immune sensitivity has been implicated in skin cancer risk. Therefore, the treatment options which can inhibit UVB-induced suppression of immune sensitivity may be useful in the management of skin cancers, including both melanoma and non-melanoma. Previously, we have shown that topical treatment of honokiol inhibits UVB induced immune suppression, which was associated with the reduction in UVB-induced inflammatory mediators in the mouse skin. Here, we have further determined the underlying mechanism of action of honokiol on UVR-induced immunosuppression including its effect on epigenetic regulators and their relationship with immune sensitivity in mouse skin. Topical treatment of C3H/HeN mice with honokiol (0.5 and 1.0 mg/cm2 skin area) in hydrophilic-cream based topical formulation significantly inhibits UVB-induced suppression of CHS response (P<0.01-0.005), which was associated with reduced levels of DNA methylation as well as Dnmt activity in the mouse skin compared with non-honokiol-treated and UVB-exposed control mice. To characterize the cell population responsible for the honokiol mediated inhibition of UVB-induced immunosuppression, we used an adoptive transfer approach. DNA-methylated (most of cells) dendritic cells (DCs), isolated from the draining lymph nodes of donor mice that had been UVB-exposed and sensitized to 2,4,-dinitrofluorobenzene (DNFB) with and without honokiol (0.5 and 1.0 mg/cm2 skin area) treatment, were transferred into naïve recipient mice. The CHS response of the recipient mice to DNFB was then measured. Honokiol treatment of UVB-exposed donor mice relieved this suppression of the CHS response in naïve mice, while the recipient mice, obtained DNA-methylated DCs from UVB-exposed donor mice that were not treated with honokiol, showed significant suppression in the CHS response. The restoration of CHS response in mice receiving DCs from honokiol treated, UV-exposed donor mice was also associated with enhanced secretion of Th1-type cytokines compared with the Th1-type cytokines from the DCs obtained from non-honokiol-treated and UVB-exposed donor mice. These data suggest that honokiol mediated inhibition of UVB induced suppression of CHS response is associated with functional activation of dendritic cells and that is dependent on DNA demethylation in DCs. Note: This abstract was not presented at the meeting. Citation Format: Santosh K. Katiyar, Tripti Singh, Harish C. Pal, Ram Prasad. Honokiol stimulates immune reactivity in UV-irradiated skin through DNA demethylation-dependent functional activation of dendritic cells in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2221. doi:10.1158/1538-7445.AM2017-2221

Dietary grape seed proanthocyanidins inactivate regulatory T cells by promoting NER-dependent DNA repair in dendritic cells in UVB-exposed skin.

Ultraviolet B (UVB) radiation induces regulatory T cells (Treg cells) and depletion of these Treg cells alleviates immunosuppression and inhibits photocarcinogenesis in mice. Here, we determined the effects of dietary grape seed proanthocyanidins (GSPs) on the development and activity of UVB-induced Treg cells. C3H/HeN mice fed a GSPs (0.5%, w/w)-supplemented or control diet were exposed to UVB (150 mJ/cm2) radiation, sensitized to 2,4-dinitrofluorobenzene (DNFB) and sacrificed 5 days later. FACS analysis indicated that dietary GSPs decrease the numbers of UVB-induced Treg cells. ELISA analysis of cultured sorted Treg cells indicated that secretion of immunosuppressive cytokines (interleukin-10, TGF-β) was significantly lower in Treg cells from GSPs-fed mice. Dietary GSPs also enhanced the ability of Treg cells from wild-type mice to stimulate production of IFNγ by T cells. These effects of dietary GSPs on Treg cell function were not found in XPA-deficient mice, which are incapable of repairing UVB-induced DNA damage. Adoptive transfer experiments revealed that naïve recipients that received Treg cells from GSPs-fed UVB-irradiated wild-type donors that had been sensitized to DNFB exhibited a significantly higher contact hypersensitivity (CHS) response to DNFB than mice that received Treg cells from UVB-exposed mice fed the control diet. There was no significant difference in the CHS response between mice that received Treg cells from UVB-irradiated XPA-deficient donors fed GSPs or the control diet. Furthermore, dietary GSPs significantly inhibited UVB-induced skin tumor development in wild-type mice but not in XPA-deficient mice. These results suggest that GSPs inactivate Treg cells by promoting DNA repair in dendritic cells in UVB-exposed skin.

Honokiol inhibits ultraviolet radiation-induced immunosuppression through inhibition of ultraviolet-induced inflammation and DNA hypermethylation in mouse skin

Ultraviolet (UV) radiation exposure induces immunosuppression, which contributes to the development of cutaneous malignancies. We investigated the effects of honokiol, a phytochemical found in plants of the genus Magnolia, on UVB-induced immunosuppression using contact hypersensitivity (CHS) as a model in C3H/HeN mice. Topical application of honokiol (0.5 and 1.0 mg/cm2 skin area) had a significant preventive effect on UVB-induced suppression of the CHS response. The inflammatory mediators, COX-2 and PGE2, played a key role in this effect, as indicated by honokiol inhibition of cyclooxygenase-2 (COX-2) expression and PGE2 production in the UVB-exposed skin. Honokiol application also inhibited UVB-induced DNA hypermethylation and its elevation of the levels of TET enzyme, which is responsible for DNA demethylation in UVB-exposed skin. This was consistent with the restoration of the CHS response in mice treated with the DNA demethylating agent, 5-aza-2′-deoxycytidine, after UVB exposure. There was no significant difference in the levels of inhibition of UVB-induced immunosuppression amongst mice that were treated topically with available anti-cancer drugs (imiquimod and 5-fluorouracil). This study is the first to show that honokiol has the ability to inhibit UVB-induced immunosuppression in preclinical model and, thus, has potential for use as a chemopreventive strategy for UVB radiation-induced malignancies.

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent.

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models. Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Imaging protective mast cells in living mice during severe contact hypersensitivity.

Contact hypersensitivity (CHS) is a common skin disease induced by epicutaneous sensitization to haptens. Conflicting results have been obtained regarding pathogenic versus protective roles of mast cells (MCs) in CHS, and this has been attributed in part to the limitations of certain models for studying MC functions in vivo. Here we describe a fluorescent imaging approach that enables in vivo selective labeling and tracking of MC secretory granules by real-time intravital 2-photon microscopy in living mice, and permits the identification of such MCs as a potential source of cytokines in different disease models. We show using this method that dermal MCs release their granules progressively into the surrounding microenvironment, but also represent an initial source of the antiinflammatory cytokine IL-10, during the early phase of severe CHS reactions. Finally, using 3 different types of MC-deficient mice, as well as mice in which IL-10 is ablated specifically in MCs, we show that IL-10 production by MCs can significantly limit the inflammation and tissue pathology observed in severe CHS reactions.

A rare subset of skin-tropic regulatory T cells expressing Il10/Gzmb inhibits the cutaneous immune response

Abstract We reported that Foxp3+ regulatory T cells (Tregs) migrating from the skin to the draining lymph node have a strong immunosuppressive effect on contact hypersensitivity (CHS) response. However, the Treg subsets that regulate the CHS response remain poorly defined. In this study, we used a combination of single-cell real-time PCR high-dimensional gene expression profiling data with spatiotemporal information about cellular movement from the mice expressing the photoconvertible protein KikGR to elucidate the role and characteristics of Treg subsets in CHS response. We found that although immunosuppressive genes Ctla4 and Tgfb1 were expressed in the majority of Tregs, Il10-expressing Tregs were rare and unexpectedly, the majority of Il10-expressing Tregs co-expressed Gzmb and displayed Th1-skewing. Furthermore, Gzmb-/Il10-expressing Treg subsets expressed the novel markers CD43 and CCR5. CD43+ CCR5+ CXCR3− Tregs highly expressed skin-tropic chemokine receptors CCR4 and CCR8. We also measured the retention of Treg subsets within inflamed skin using KikGR mice, and found that the subset of Tregs that was most highly retained in the skin, CD43+ CCR5+ CXCR3− Tregs, had superior in vivo inhibitory function to other Treg subsets. These results suggested that even if only present in small numbers, highly activated Tregs that co-express Gzmb and Il10 and that have the capacity to remain in inflamed tissue are likely to be clinically relevant due to the role of these molecules in the control of excessive immune responses. Taken together, the identification of a rare Treg subset co-expressing multiple immunosuppressive molecules and having tissue-remaining capacity offers a novel strategy for the control of skin inflammatory responses.

549 Hyaluronan synthase 3 induces epidermal hyaluronan production by hapten stimulation and modulate contact hypersensitivity response

549 Hyaluronan synthase 3 induces epidermal hyaluronan production by hapten stimulation and modulate contact hypersensitivity response

573 Arginase1/Nos2 imbalance in macrophages mediates cutaneous contact hypersensitivity responses

573 Arginase1/Nos2 imbalance in macrophages mediates cutaneous contact hypersensitivity responses

A unique CD9+CD80+ regulatory B cell inhibits contact hypersensitivity response

A unique CD9+CD80+ regulatory B cell inhibits contact hypersensitivity response

Corrigendum to "Inhibition of 2,4-dinitrofluorobenzene-induced contact hypersensitivity reaction by antidepressant drugs" [Pharmacol. Rep. 65 (2013) 1237-1246

Corrigendum to "Inhibition of 2,4-dinitrofluorobenzene-induced contact hypersensitivity reaction by antidepressant drugs" [Pharmacol. Rep. 65 (2013) 1237-1246

Dermal γδ T Cells Do Not Freely Re-Circulate Out of Skin and Produce IL-17 to Promote Neutrophil Infiltration during Primary Contact Hypersensitivity.

The role of mouse dermal γδ T cells in inflammatory skin disorders and host defense has been studied extensively. It is known that dendritic epidermal T cells (DETC) have a monomorphic γδ T cell receptor (TCR) and reside in murine epidermis from birth. We asked if dermal γδ cells freely re-circulated out of skin, or behaved more like dermal resident memory T cells (TRM) in mice. We found that, unlike epidermal γδ T cells (DETC), dermal γδ cells are not homogeneous with regard to TCR, express the tissue resident T cell markers CD69 and CD103, bear skin homing receptors, and produce IL-17 and IL-22. We created GFP+: GFP− parabiotic mice and found that dermal γδ T cells re-circulate very slowly—more rapidly than authentic αβ TCR TRM, but more slowly than the recently described dermal αβ TCR T migratory memory cells (TMM). Mice lacking the TCR δ gene (δ-/-) had a significant reduction of 2,4-dinitrofluorobenzene (DNFB)-induced contact hypersensitivity (CHS). We created mice deficient in dermal γδ T cells but not DETC, and these mice also showed a markedly reduced CHS response after DNFB challenge. The infiltration of effector T cells during CHS was not reduced in dermal γδ T cell-deficient mice; however, infiltration of Gr-1+CD11b+ neutrophils, as well as ear swelling, was reduced significantly. We next depleted Gr-1+ neutrophils in vivo, and demonstrated that neutrophils are required for ear swelling, the accepted metric for a CHS response. Depletion of IL-17-producing dermal Vγ4+ cells and neutralization of IL-17 in vivo, respectively, also led to a significantly reduced CHS response and diminished neutrophil infiltration. Our findings here suggest that dermal γδ T cells have an intermediate phenotype of T cell residence, and play an important role in primary CHS through producing IL-17 to promote neutrophil infiltration.

Suppressive Effects of Mesenchymal Stem Cells in Adipose Tissue on Allergic Contact Dermatitis.

BackgroundAllergic contact dermatitis (ACD), which is accelerated by interferon (IFN)-γ and suppressed by interleukin (IL)-10 as regulators, is generally self-limited after removal of the contact allergen. Adipose tissue-derived multipotent mesenchymal stem cells (ASCs) potentially exert immunomodulatory effects. Considering that subcutaneous adipose tissue is located close to the site of ACD and includes mesenchymal stem cells (MSCs), the MSCs in adipose tissue could contribute to the self-limiting course of ACD.ObjectiveThe aims of the present study were to elucidate the effects of MSCs in adipose tissue on ACD and to examine any cytokine-mediated mechanisms involved.MethodsEar thickness in a C57BL/6 mouse model of ACD using contact hypersensitivity (CHS) elicited by 2,4,6-trinitro-1-chlorobenzene was evaluated as a marker of inflammation level. Five and nine mice were injected with ASCs and phosphate-buffered saline (PBS), respectively. After ASC or PBS injection, real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay were performed.ResultsHistology showed that CHS was self-limited and ear thickness was suppressed by ASCs in a dose-dependent manner. IFN-γ expression in the elicited skin site and regional lymph nodes was significantly lower in ASC-treated mice than in control mice. IL-10 expression did not differ between treated and control mice. The suppressive effects of ASCs on CHS response did not differ between IL-10 knock-out C57BL/6 mice and wild-type mice.ConclusionThe present findings suggest that MSCs in adipose tissue may contribute to the self-limiting course of ACD through decreased expression of IFN-γ, but not through increased expression of IL-10.

Liver-specific natural killer cells: discovery, validation, and functions

Nature killer (NK) cells are an important component of the innate immune system. Most of our current knowledge about NK cells is derived from previous studies of conventional NK cells that are circulating and widely distributed. With predominant functions in innate immunity, the liver contains abundant NK cells with phenotypic and functional heterogeneity. As compared with conventional NK cells, liver-specific NK cells exhibit unique phenotypic features and require different transcription factors for their development. Moreover, liver-specific NK cells are tissue-resident cells and have the ability to mount contact hypersensitivity responses. These findings have greatly motivated the study of tissue-specific NK cell subsets that are distinct from conventional NK cells. In this review, we summarize the research background and discovery of liver-specific NK cells and discuss their developmental requirements and functional properties.

Visualization of the T Cell Response in Contact Hypersensitivity.

Contact hypersensitivity (CHS) is the most basic murine model for type IV hypersensitivity. This dermatitis model is mediated by hapten-sensitized, skin-infiltrating T cells. Recent intravital imaging studies have demonstrated the dynamic migratory property of skin-infiltrating T cells and the orchestrated interaction of T cells with dermal dendritic cells. Multiphoton microscopy enables the direct, three-dimensional, and minimally invasive imaging of in vivo skin samples with high spatiotemporal resolution. Here, we describe a basic method for the intravital imaging of skin-infiltrating T cells in the DNFB-induced CHS response.

Mast Cells Limit the Exacerbation of Chronic Allergic Contact Dermatitis in Response to Repeated Allergen Exposure.

Allergic contact dermatitis is a chronic T cell-driven inflammatory skin disease that is caused by repeated exposure to contact allergens. Based on murine studies of acute contact hypersensitivity, mast cells (MCs) are believed to play a role in its pathogenesis. The role of MCs in chronic allergic contact dermatitis has not been investigated, in part because of the lack of murine models for chronic contact hypersensitivity. We developed and used a chronic contact hypersensitivity model in wild-type and MC-deficient mice and assessed skin inflammatory responses to identify and characterize the role of MCs in chronic allergic contact dermatitis. Ear swelling chronic contact hypersensitivity responses increased markedly, up to 4-fold, in MC-deficient KitW-sh/W-sh (Sash) and MCPT5-Cre+iDTR+ mice compared with wild-type mice. Local engraftment with MCs protected Sash mice from exacerbated ear swelling after repeated oxazolone challenge. Chronic contact hypersensitivity skin of Sash mice exhibited elevated levels of IFN-γ, IL-17α, and IL-23, as well as increased accumulation of Ag-specific IFN-γ-producing CD8+ tissue-resident memory T (TRM) cells. The CD8+ T cell mitogen IL-15, which was increased in oxazolone-challenged skin of Sash mice during the accumulation of cutaneous TRM cells, was efficiently degraded by MCs in vitro. MCs protect from the exacerbated allergic skin inflammation induced by repeated allergen challenge, at least in part, via effects on CD8+ TRM cells. MCs may notably influence the course of chronic allergic contact dermatitis. A better understanding of their role and the underlying mechanisms may lead to better approaches for the treatment of this common, disabling, and costly condition.

The Short-Chain Fatty Acid Sodium Butyrate Functions as a Regulator of the Skin Immune System

There is evidence that gut commensal microbes affect the mucosal immune system via expansion of regulatory T cells (Tregs) in the colon. This is mediated via short-chain fatty acids, bacterial metabolites generated during fiber fermentation, which include butyrate, propionate, and acetate. We postulated that short-chain fatty acids produced by commensal skin bacteria may also activate resident skin Tregs, the activity of which is diminished in certain inflammatory dermatoses. Sodium butyrate (SB) either injected subcutaneously or applied topically onto the ears of hapten-sensitized mice significantly reduced the contact hypersensitivity reaction. This effect was histone acetylation-dependent because suppression was abrogated by anacardic acid, a histone acetyltransferase inhibitor. The genes encoding for the Treg-specific transcription factor foxp3 and for IL-10 were up-regulated upon treatment with sodium butyrate, as determined by quantitative real-time reverse transcription-PCR. Immunofluorescence analysis showed enhanced numbers of Foxp3-positive cells in sodium butyrate-treated skin. Additionally, CD4+CD25- nonregulatory human T cells exerted suppressive features upon incubation with sodium butyrate. This indicates that Tregs can be induced by short-chain fatty acids, suggesting (i) that resident skin microbes may prevent exaggerated inflammatory responses by exerting a down-regulatory function and thereby maintaining a stable state under physiologic conditions and (ii) that short-chain fatty acids may be used therapeutically to mitigate inflammatory skin reactions.

Inhibitory effect of clove methanolic extract and eugenol on dendritic cell functions

Caryophyllata Flos or clove is widely used as a condiment and in Chinese medicine. It reportedly helps relieve asthma and allergies; however, the underlying mechanisms remain unclear. In particular, the mechanism affecting dendritic cells (DCs), which play a critical role in the immune response, remains unknown. In this study, we examine the effects of Caryophyllata Flos methanolic extract (CFME) and its major compound, eugenol, on DC functions. Our results showed that CFME and eugenol significantly inhibited DC activation and maturation. The IC50s of CFME and eugenol were approximately 25 µg/mL and 50 µM, respectively. CFME and eugenol halted T-cell proliferation. Contact hypersensitivity responses were inhibited in mice cosensitized with either CFME or eugenol. We demonstrated for the first time that clove and its major active ingredient, eugenol, exhibited a significant immunosuppressive effect on DC functions, revealing that clove is a functional food that can ameliorate chronic inflammation and autoimmunity.

Aquaporin-9-expressing neutrophils are required for the establishment of contact hypersensitivity

Aquaporins (AQPs, AQP0-12) are membrane water/glycerol channel proteins that participate in various cellular functions in many cell types. AQP9 is expressed in several immune cells including neutrophils; however, its role in cutaneous immune response remains unknown. Here we show the involvement of AQP9 in skin allergic inflammation using AQP9 knockout (AQP9−/−) mice and the contact hypersensitivity (CHS) model. First, AQP9−/− mice showed impairment of CHS responses to 2,4-dinitrofluorobenzene (DNFB) compared with wild-type (WT) mice. The sensitization phase of CHS was examined by evaluating the immune cells accumulated in skin draining lymph nodes (LNs) after DNFB application. Adoptive transfer of AQP9−/− LNs cells into the ears of WT recipients resulted in impaired CHS response, indicating the defect of sensitization in AQP9−/−. IL-17 production was decreased in AQP9−/− compared with WT LNs cells, though the T cell proliferation and IFN-gamma production levels were comparable. WT mice showed high neutrophil accumulation in LNs at 18 h after DNFB application, but it was diminished in AQP9−/− mice. In accordance, we found the attenuation of AQP9−/− neutrophil migration to LNs after DNFB application. Furthermore, the neutrophil migration in response to CCR7 ligands was suppressed in AQP9−/− using chemotaxis chambers. Finally, we found that the administration of Gr-1 (neutrophil) antibody during the sensitization phase suppressed IL-17 production from LNs cells as well as CHS response in WT mice, suggesting the implication of neutrophils for IL-17 production during the development of CHS. These data suggest that AQP9-expressing neutrophils play an important role in the sensitization phase of CHS through their migration function.