Effect of a topical steroid on gene expressions for chemokines in mice with contact hypersensitivity

Modulation of allergic contact dermatitis via gut microbiota modified by diet, vitamins, probiotics, prebiotics, and antibiotics

Allergic contact dermatitis is one of the most common recorded occupational diseases. There are many different substances that the skin comes into contact with on a daily basis and that can cause ACD, e.g., preservatives, surfactants, and antimicrobial agents. The development of a mouse model of ACD has provided insight into the immune mechanisms involved. Drugs used in the treatment of skin diseases have many side effects. Therefore, alternative methods of suppressing the immune response to reduce the symptoms of skin diseases are being sought. In recent years, high hopes have been placed on dietary modulation and supplementation to affect the intestinal microbial composition and promote anti-inflammatory responses. In addition, other studies have shown the crucial role of intestinal microbiota in many immune-mediated diseases. Recognition and characterization of pro- and anti-inflammatory nutrients and supplements may be crucial to support the treatment of diseases such as atopic dermatitis, acne vulgaris, psoriasis, and allergic contact dermatitis.

Inhibitory effects of dietary soy isoflavone and gut microbiota on contact hypersensitivity in mice

Soy isoflavones (SIs) are abundant in soybeans and have inhibitory effects on contact hypersensitivity (CHS), which is often used as a mouse model for allergic contact dermatitis (ACD); however, their therapeutic mechanisms remain unknown. We studied the suppressive activity of dietary SI and gut microbiota on dinitrofluorobenzene (DNFB)-induced CHS. Low-dose SI diets alleviated DNFB-induced ear swelling and oedema and decreased infiltration of Gr-1-positive cells into ear tissue. In addition, dietary SIs also decreased interleukin-1β and chemokine (C-X-C motif) ligand 1 production in ear tissue compared to controls. Furthermore, ciprofloxacin and metronidazole treatments blocked the suppressive activity of dietary SIs on CHS, whereas vancomycin treatment had a marginal effect. These antibiotic treatments differed in their effects on the gut microbiota composition. These results demonstrated that consumption of physiologically relevant doses of SIs reduced CHS symptoms, and suggested that the gut microbiota influenced their suppressive activities on CHS.

Impact of soymilk consumption on 2,4-dinitrofluorobenzene-induced contact hypersensitivity and gut microbiota in mice

Soymilk is rich in phytochemicals such as soy isoflavones (SIs) and soyasaponins (SSs). Dietary SIs and SSs display inhibitory effects on contact hypersensitivity (CHS), which was reported in a mouse model for allergic contact dermatitis (ACD); however, the beneficial effects of soymilk consumption on CHS remain unknown. Here, we studied the effects of drinking soymilk on CHS and gut microbiota. Soymilk consumption attenuated ear oedema and swelling, decreased the infiltration of Gr-1-positive cells into ear tissues, and reduced the production of chemokine (C-X-C motif) ligand 2 and triggering receptor expressed on myeloid cells-1 in ear tissues. The analysis of bacterial 16S ribosomal RNA gene sequences indicated that CHS caused changes in the gut microbiota structure and that consuming soymilk reduced these changes. These results suggest that soymilk consumption may be of therapeutic value for patients with ACD and may help control the balance of intestinal microbiota.

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

Foxp3⁺ regulatory T cells (Tregs) migrating from the skin to the draining lymph node (dLN) have a strong immunosuppressive effect on the cutaneous immune response. However, the subpopulations responsible for their inhibitory function remain unclear. We investigated single-cell gene expression heterogeneity in Tregs from the dLN of inflamed skin in a contact hypersensitivity model. The immunosuppressive genes Ctla4 and Tgfb1 were expressed in the majority of Tregs. Although Il10-expressing Tregs were rare, unexpectedly, the majority of Il10-expressing Tregs co-expressed Gzmb and displayed Th1-skewing. Single-cell profiling revealed that CD43⁺ CCR5⁺ Tregs represented the main subset within the Il10/Gzmb-expressing cell population in the dLN. Moreover, CD43⁺ CCR5⁺ CXCR3⁻ Tregs expressed skin-tropic chemokine receptors, were preferentially retained in inflamed skin and downregulated the cutaneous immune response. 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.

Update of immune events in the murine contact hypersensitivity model: toward the understanding of allergic contact dermatitis

Allergic contact dermatitis (ACD) is one of the most common skin diseases, consisting of sensitization and elicitation phases. With the advancement of technology and the discovery of new types of immune cells, our knowledge of the immunological mechanisms of contact hypersensitivity (CHS) as a murine model of ACD has expanded significantly in the past decade. For example, by introducing regulatory T cells, CD4(+) T-helper 17 cells, and Langerin-positive dermal dendritic cells, the initiation and termination mechanism of CHS has been revealed. In addition, the role of mast cells in CHS, long a matter of debate, has become apparent by developing conditional mast cell-deficient mice. Moreover, the role of the innate immunity system, such as that of Toll-like receptor signaling, has made a breakthrough in this field. In this review, we will integrate the recent advancement of immunological mechanisms of both the sensitization and elicitation phases of CHS into the classic view, and we will discuss updated mechanisms on its development and future directions.

Role of four major components in the effect of Si-Ni-San, a traditional Chinese prescription, against contact sensitivity in mice

Previously, we demonstrated the inhibitory effects of Si-Ni-San, a traditional Chinese prescription, on picryl chloride-induced ear contact sensitivity (PCl-CS). This study aimed to evaluate the role of the four major constituents contained in the prescription (saikosaponins, paeoniflorin, naringin and glycyrrhizin) in the inhibitory effect. When administered during the induction phase, saikosaponin a and glycyrrhizin showed significant inhibitory effects, while paeoniflorin and naringin did not. These components in Si-Ni-San also inhibited the activation and proliferation of T lymphocytes as well as the production of cytokines such as tumour necrosis factor-alpha and interferon-gamma to different extents. Saikosaponin a and paeoniflorin dose-dependently reduced the splenocyte adhesion to type I collagen, while glycyrrhizin only showed a slight tendency. Furthermore, treatment with glycyrrhizin or saikosaponin a, rather than paeoniflorin or naringin, moderately inhibited the matrix metalloproteinase (MMP)-2 activity of the splenocytes from PCl-CS mice, and the combination of all four components showed a strong inhibition against MMP-2. Moreover, the components markedly decreased the serum level of nitric oxide in PCl-sensitized mice. The results indicated that saikosaponin a and glycyrrhizin may be the major contributors in the alleviation effect of Si-Ni-San on contact sensitivity, and paeoniflorin and naringin may exhibit a co-operative effect.

Nitric oxide inhibits T cell adhesion and migration by down-regulation of β1-integrin expression in immunologically liver-injured mice

Our previous study has reported that nitric oxide (NO) exerts a protective role in immunologically liver-injured mice induced by delayed-type hypersensitivity to picryl chloride. To explore the mechanism of the protection, we have now examined the effect of NO on T cell adhesion and migration. First, we isolated hepatocytes and nonparenchymal cells from the liver-injured mice and separated the nonparenchymal cells into Kupffer cell-enriched and lymphocyte-enriched populations. When these hepatocytes or the fractions of nonparenchymal cells were co-cultured with spleen T cells of the liver-injured mice in a Transwell system, the adhesive potential of the T cells was significantly inhibited in the presence of hepatocytes or the Kupffer cell-enriched population but not the lymphocyte-enriched population of nonparenchymal cells. This effect was dependent on NO production. The NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) could reverse this inhibition of cell adhesion and also decrease NO production. To confirm this effect of NO on T cells, we further examined the role of exogenous or endogenous NO on the adhesive activity of the Jurkat T cell line. As a result, the NO donor, S-nitroso-N-acetyl penicillamine (SNAP) caused a dose-dependent inhibition of the adhesion of Jurkat T cells. Furthermore, the binding ability of Jurkat T cells to collagen decreased gradually after co-incubation with macrophages stimulated by LPS+IFN-gamma, an effect which correlated well with the increasing NO level in the medium. Such opposite changes in cell adhesion and in NO production were also markedly reversed by L-NMMA. Moreover, treatment with SNAP reduced adhesion, transmigration, matrix metalloproteinase-9 production and beta1-integrin expression of spleen T cells of the liver-injured mice. Taken together, these findings suggest that NO can function as a down-regulator of T cell mobility, which might be one of the mechanisms by which NO exerts its protective effect in T cell-mediated liver injury.

Anti-inflammatory activities of aqueous extract from Radix Ophiopogon japonicus and its two constituents

To provide some pharmacological evidence for its clinical use in inflammatory diseases, anti-inflammatory effect of the aqueous extract from Radix Ophiopogon japonicus (ROJ-ext), a traditional Chinese herb, was examined in mouse and rat models. ROJ-ext significantly inhibited xylene-induced ear swelling and carrageenan-induced paw edema in mice when given orally at doses of 25 and 50 mg/kg. Moreover, ROJ-ext also remarkably suppressed carrageenan-induced pleural leukocyte migration in rats and zymosan A-evoked peritoneal total leukocyte and neutrophil migration in mice, while had no obvious effect on pleural prostaglandin E2 level. Furthermore, two active compounds were isolated from ROJ-ext and identified as ruscogenin and ophiopogonin D. As the results, ROJ-ext, ruscogenin and ophiopogonin D dose-dependently reduced phorbol-12-myristate-13-acetate (PMA)-induced adhesion of HL-60 cells to ECV304 cells, with IC50 of 42.85 microg/ml, 7.76 nmol/l and 1.38 nmol/l, respectively. However, they showed no inhibitory effect on PMA-induced cyclooxygense-2 (COX-2) mRNA expression in ECV304 cells. Ruscogenin and ophiopogonin D also notably decreased zymosan A-induced peritoneal leukocyte migration, in comparison with ROJ-ext. These results demonstrate that ROJ-ext presents remarkable anti-inflammatory activity and ruscogenin and ophiopogonin D are two of its active components, which supported its traditional use in the treatment of various diseases associated with inflammation.

Aqueous extract from aerial parts of Artemisia vestita, a traditional Tibetan medicine, reduces contact sensitivity in mice by down-regulating the activation, adhesion and metalloproteinase production of T lymphocytes

In the present paper, the effect of the aqueous extract from aerial parts of Artemisia vestita (AV-ext), a traditional Tibetan medicine, on ear contact sensitivity was examined. AV-ext significantly reduced the ear swelling when administered during the induction phase of picryl-chloride (PCl)-induced ear contact sensitivity in mice. The extract also showed a dose-dependent inhibition on lymphocyte proliferation and IL-2 production in Con A-activated spleen cells. The proliferation inhibition was confirmed in the mixed lymphocytes reaction. Furthermore, the adhesion of the isolated spleen cells from PCl-sensitized mice to type IV collagen was significantly decreased in a dose-dependent manner by AV-ext. Such decrease was also seen in AV-ext-treated Jurkat T cells and the T cells purified from above spleen cells. The purified spleen T cells from PCl-sensitized mice produced more matrix metalloproteinase-9 (MMP-9) than naive T cells, and AV-ext remarkably reduced MMP-9 production both in vivo and in vitro. These results suggest that AV-ext may alleviate contact sensitivity through blocking the activation of T lymphocytes and decreasing their localization to the inflammatory sites via down-regulating the potential of cell adhesion and metalloproteinase production.