The effect of synthetic retinoid, Am80, on T helper cell development and antibody production in murine collagen-induced arthritis

Tamibarotene Ameliorates Bleomycin-Induced Dermal Fibrosis by Modulating Phenotypes of Fibroblasts, Endothelial Cells, and Immune Cells

Tamibarotene (Am80) is a synthetic retinoid that modulates the pathologic processes of various autoimmune and inflammatory diseases and their animal models. We here investigated the therapeutic potential of Am80 against systemic sclerosis using its animal models. Am80 significantly attenuated dermal and hypodermal fibrosis in bleomycin (BLM)-treated mice and tight skin 1 mice, respectively. Consistently, Am80 significantly suppressed the expression of various molecules related to tissue fibrosis, including transforming growth factor-β1, connective tissue growth factor, IL-4, IL-10, IL-13, IL-17A, tumor necrosis factor-α, IFN-γ, and monocyte chemotactic protein 1 in the lesional skin of BLM-treated mice. Furthermore, Am80 decreased the proportion of effector T cells, while increasing that of naïve T cells among CD4+ T cells in the draining lymph nodes of BLM-treated mice. Moreover, a series of BLM-induced pathologic events, including endothelial-to-mesenchymal transition; ICAM-1 expression in endothelial cells; the infiltration of macrophages, mast cells, and lymphocytes; and M2 macrophage differentiation, were attenuated by Am80. Importantly, Am80 directly reversed the profibrotic phenotype of transforming growth factor-β1-treated dermal fibroblasts, suppressed ICAM-1 expression in endothelial cells, and promoted M1 macrophage differentiation in vitro. Collectively, Am80 inhibits the development of experimental dermal fibrosis by reversing the profibrotic phenotype of various cell types and would be a candidate for therapeutic drugs against dermal fibrosis of systemic sclerosis.

Abrogation of CC chemokine receptor 9 ameliorates collagen-induced arthritis of mice

INTRODUCTION

Biological drugs are effective in patients with rheumatoid arthritis (RA), but increase severe infections. The CC chemokine receptor (CCR) 9 antagonist was effective for Crohn's disease without critical adverse effects including infections in clinical trials. The present study was carried out to explore the pathogenic roles of chemokine (C-C motif) ligand (CCL) 25 and its receptor, CCR9, in autoimmune arthritis and to study if the CCR9 antagonist could be a new treatment for RA.

METHODS

CCL25 and CCR9 expression was examined with immunohistochemistry and Western blotting. Concentration of interleukin (IL)-6, matrix metalloproteinase (MMP)-3 and tumor necrosis factor (TNF)-α was measured with enzyme-linked immunosorbent assays. Effects of abrogating CCR9 on collagen-induced arthritis (CIA) was evaluated using CCR9-deficient mice or the CCR9 antagonist, CCX8037. Fluorescence labeled-CD11b+ splenocytes from CIA mice were transferred to recipient CIA mice and those infiltrating into the synovial tissues of the recipient mice were counted.

RESULTS

CCL25 and CCR9 proteins were found in the RA synovial tissues. CCR9 was expressed on macrophages, fibroblast-like synoviocytes (FLS) and dendritic cells in the synovial tissues. Stimulation with CCL25 increased IL-6 and MMP-3 production from RA FLS, and IL-6 and TNF-α production from peripheral blood monocytes. CIA was suppressed in CCR9-deficient mice. CCX8037 also inhibited CIA and the migration of transferred CD11b+ splenocytes into the synovial tissues.

CONCLUSIONS

The interaction between CCL25 and CCR9 may play important roles in cell infiltration into the RA synovial tissues and inflammatory mediator production. Blocking CCL25 or CCR9 may represent a novel safe therapy for RA.

Cannabinoid receptor 2 as a potential therapeutic target in rheumatoid arthritis

Background

Some of cannabinoids, which are chemical compounds contained in marijuana, are immunosuppressive. One of the receptors, CB receptor 1 (CB₁), is expressed predominantly by the cells in the central nervous system, whereas CB receptor 2 (CB₂) is expressed primarily by immune cells. Theoretically, selective CB₂ agonists should be devoid of psychoactive effects. In this study, we investigated therapeutic effects of a selective CB₂ agonist on arthritis.

Methods

The expression of CB₂ was analyzed with immunohistochemistry and Western blotting. Interleukin (IL)-6, matrix metalloproteinase-3 (MMP-3), and chemokine (C-C motif) ligand 2 (CCL2) were quantified with enzyme-linked immunosorbent assays (ELISA). Osteoclastogenesis was assessed with tartrate-resistant acid phosphatase staining and the resorption of coated-calcium phosphate. Effect of JWH133, a selective CB₂ agonist, on murine collagen type II (CII)-induced arthritis (CIA) was evaluated with arthritis score, and histological and radiographic changes. IFN-γ and IL-17 production by CII-stimulated splenocytes and serum anti-CII Ab were analyzed by ELISA.

Results

Immunohistochemistry showed that CB₂ was expressed more in the synovial tissues from the rheumatoid joints than in those from the osteoarthritis joints. CB₂ expression on RA FLS was confirmed with Western blot analysis. JWH133 inhibited IL-6, MMP-3, and CCL2 production from tumor necrosis factor-α-stimulated fibroblast-like synoviocytes (FLS) derived from the rheumatoid joints, and osteoclastogenesis of peripheral blood monocytes. Administration of JWH133 to CIA mice reduced the arthritis score, inflammatory cell infiltration, bone destruction, and anti-CII IgG1 production.

Conclusion

The present study suggests that a selective CB₂ agonist could be a new therapy for RA that inhibits production of inflammatory mediators from FLS, and osteoclastogenesis.

Could retinoids be a potential treatment for rheumatic diseases?

Retinoid, a derivative of vitamin A, is a general term used to describe compounds that bind to and activate retinoic acid receptors [RARs (RARα, RARβ, and RARγ)] and/or retinoid X receptors [RXRs (RXRα, RXRβ, and RXRγ)]. They have been shown to surpress the differentiation of Th1/Th17 cells and induce the development of Th1/regulatory T cells. They also affect the proliferation of B cells as both an inducer and suppressor. Furthermore, retinoids may induce the maturation of dendritic cells and production of interleukin-10 from monocytes/macrophages. We recently demonstrated that retinoids suppressed the production of reactive oxygen species, the release of elastase from neutrophils by inhibiting mitogen-activated protein kinase signals, and both the migration speed and chemotaxis directionality of neutrophils. Retinoids, such as all-trans retinoic acid and tamibarotene, were previously shown to have positive effects on animal models of several rheumatic diseases, including arthritis, myositis, and vasculitis in vivo. Moreover, retinoids have been used in a pilot study to effectively treat patients with lupus nephritis and systemic sclerosis. We herein reviewed the effects of retinoids on immune cells, animal models of rheumatic diseases, and rheumatic patients.

Necessity of lysophosphatidic acid receptor 1 for development of arthritis

OBJECTIVE

Lysophosphatidic acid (LPA) is a bioactive lipid that binds to a group of cell surface G protein-coupled receptors (LPA receptors 1-6 [LPA1-6 ]) and has been implicated as an important mediator of angiogenesis, inflammation, and cancer growth. This study was undertaken to analyze the effects of LPA1 on the development of arthritis.

METHODS

Expression of LPA receptors on synovial tissue was analyzed by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. The effects of abrogation of LPA1 on collagen-induced arthritis (CIA) were evaluated using LPA1 -deficient mice or LPA1 antagonist. Migrating fluorescence-labeled CD11b+ splenocytes, which were transferred into the synovium of mice with CIA, were counted. CD4+ naive T cells were incubated under Th1-, Th2-, or Th17-polarizing conditions, and T helper cell differentiation was assessed. Osteoclast formation from bone marrow cells was examined.

RESULTS

LPA1 was highly expressed in the synovium of patients with rheumatoid arthritis (RA) compared with that of patients with osteoarthritis. LPA1 -deficient mice did not develop arthritis following immunization with type II collagen (CII). LPA1 antagonist also ameliorated murine CIA. Abrogation of LPA1 was associated with reductions in cell infiltration, bone destruction in the joints, and interleukin-17 production from CII-stimulated splenocytes. Infiltration of transferred CD11b+ macrophages from LPA1 -deficient mice into the synovium was suppressed compared with infiltration of macrophages from wild-type mice. LPA1 antagonist inhibited the infiltration of macrophages from wild-type mice. Differentiation into Th17, but not Th1 or Th2, and osteoclast formation were also suppressed under conditions of LPA1 deficiency or LPA1 inhibition in vitro.

CONCLUSION

Collectively, these results indicate that LPA/LPA1 signaling contributes to the development of arthritis via cellular infiltration, Th17 differentiation, and osteoclastogenesis. Thus, LPA1 may be a promising target molecule for RA therapy.

Synthetic retinoid Am80 ameliorates chronic graft-versus-host disease by down-regulating Th1 and Th17

Chronic GVHD (cGVHD) is a main cause of late death and morbidity after allogeneic hematopoietic cell transplantation, but its pathogenesis remains unclear. We investigated the roles of Th subsets in cGVHD with the use of a well-defined mouse model of cGVHD. In this model, development of cGVHD was associated with up-regulated Th1, Th2, and Th17 responses. Th1 and Th2 responses were up-regulated early after BM transplantation, followed by a subsequent up-regulation of Th17 cells. Significantly greater numbers of Th17 cells were infiltrated in the lung and liver from allogeneic recipients than those from syngeneic recipients. We then evaluated the roles of Th1 and Th17 in cGVHD with the use of IFN-γ-deficient and IL-17-deficient mice as donors. Infusion of IFN-γ(-/-) or IL-17(-/-) T cells attenuated cGVHD in the skin and salivary glands. Am80, a potent synthetic retinoid, regulated both Th1 and Th17 responses as well as TGF-β expression in the skin, resulting in an attenuation of cutaneous cGVHD. These results suggest that Th1 and Th17 contribute to the development of cGVHD and that targeting Th1 and Th17 may therefore represent a promising therapeutic strategy for preventing and treating cGVHD.