Yi-Fu Yang

A non-peptide CCR5 antagonist inhibits collagen-induced arthritis by modulating T cell migration without affecting anti-collagen T cell responses

The chemokine receptors CCR5 and CXCR3 have been implicated as playing a central role in directing a Th1 inflammatory response. Here, we investigated whether a synthetic CCR5 antagonist affects the process of T cell migration to sites of inflammation. Immunization of DBA/1 mice with type II collagen resulted in typical arthritis, which is associated with cellular infiltration. Treatment with a CCR5 antagonist strikingly affected the development of arthritis by reducing both incidence and severity of disease. There was no substantial difference between collagen‐immunized mice with and without antagonist treatment in the induction of anti‐collagen T cell responses and the capacity to produce IL‐12. This endogenous IL‐12 functioned to induce comparable levels of CCR5 in these two immunized groups of T cells. Whereas a massive infiltration of inflammatory cells including CCR5+ T cells occurred in the joints of mice immunized without antagonist, cellular infiltration in the antagonist‐treated group was only marginal. These results indicate that administration of a CCR5 antagonist inhibits the development of arthritis not by affecting the generation of collagen‐sensitized T cells but by interfering with their migration to joint lesions.

Investigation of the immunosuppressive activity of artemether on T-cell activation and proliferation

Artemisinin and its derivatives exhibit potent immunosuppressive activity. The purpose of the current study was to examine the immunosuppressive activity of artemether directly on T lymphocytes and to explore its potential mode of action.

Oral administration of artemisinin analog SM934 ameliorates lupus syndromes in MRL/lpr mice by inhibiting Th1 and Th17 cell responses

OBJECTIVE SM934, an artemisinin derivative, possesses potent antiproliferative and antiinflammatory properties. The aim of this study was to examine the effects and explore the mechanisms of SM934 to treat autoimmune disease in lupus-prone female MRL/lpr mice. METHODS In vitro, the effects of SM934 on the activation of polyclonal CD4+ T cells and the differentiation of naive CD4+ T cells were examined. In vivo, the preventative or therapeutic effects of SM934 in MRL/lpr mice were investigated. Ex vivo, the mechanisms of treatment were explored according to the immunologic correlates of disease. RESULTS In vitro, SM934 inhibited interferon-γ (IFNγ) and interleukin-17 (IL-17) production from polyclonal CD4+ T cells activated by T cell receptor engagement and the differentiation of naive CD4+ T cells into Th1 and Th17 cells, but not Treg cells. In vivo, 12-week-old MRL/lpr mice treated with SM934 for 4 weeks showed significantly ameliorated proteinuria and renal lesion severity; decreased levels of blood urea nitrogen, serum IFNγ, and serum anti-double-stranded DNA antibodies; decreased spleen size; and a lower percentage of CD3+B220+CD4-CD8- T cells; 16-week-old MRL/lpr mice treated with SM934 for 8 weeks avoided severe proteinuria and survived longer. Ex vivo, SM934 treatment elevated the percentage of Treg cells, inhibited the development of Th1 and Th17 cells, and impeded the comprehensive activation of STAT-1, STAT-3, and STAT-5 proteins in splenocytes. CONCLUSION Taken together, the results of this study demonstrated that the artemisinin analog SM934 had therapeutic effects in lupus-prone female MRL/lpr mice by inhibiting both Th1 cell and Th17 cell responses. Moreover, this study indicated that both IFNγ and IL-17 are required for the elicitation and development of murine lupus.

The new water-soluble artemisinin derivative SM905 ameliorates collagen-induced arthritis by suppression of inflammatory and Th17 responses

Our previous study showed that SM905, a novel artemisinin derivative, exhibited potent immunosuppressive activity. In this study, we evaluate preventive and therapeutic effect of SM905 on collagen‐induced arthritis (CIA) in DBA/1 mice, and investigate its mechanisms both in inflammatory and autoimmune aspects of the disease.

IL-12 as well as IL-2 upregulates CCR5 expression on T cell receptor-triggered human CD4+ and CD8+ T cells.

The expression of chemokine receptors on leukocytes is related to their activation state. However, the exact mechanism underlying the induction of each chemokine receptor is poorly understood. Here, we investigated how CCR5, a chemokine receptor implicated in T cell trafficking and HIV infection, is induced in human T cells. CCR5 was marginally detected on a freshly prepared human peripheral blood mononuclear cell (PBMC) population. Long-term (8-day) stimulation of PBMC with IL-2 resulted in high levels of CCR5 expression on T cells. IL-12 failed to induce CCR5 on T cells in such a directly stimulated PBMC population. Stimulation of PBMC T cells with anti-CD3 plus anti-CD28 induced detectable albeit very low levels of CCR5 along with the induction of IL-12 receptor. However, these TCR-triggered T cells expressed much higher levels of CCR5 when stimulated with IL-12. Although IL-2 also induced CCR5 expression, CCR5 expression was more potent in IL-12 than IL-2 stimulation. These results indicate that, in addition to IL-2, IL-12 plays an important role in the induction of CCR5 expression on T cells, particularly TCR-triggered T cells.

COX-2 inhibitors ameliorate experimental autoimmune encephalomyelitis through modulating IFN-γ and IL-10 production by inhibiting T-bet expression

The COX-2 inhibitors Rofecoxib (Rof) and Lumiracoxib (Lum) were evaluated in experimental autoimmune encephalomyelitis (EAE), the model of multiple sclerosis (MS). Administration of Rof and Lum significantly reduced the incidence and severity of EAE, which was associated with the inhibition of MOG 35-55 lymphocyte recall response, anti-MOG 35-55 T cell responses, and modulation of cytokines production. In vitro Rof and Lum inhibited primary T cells proliferation and modulated cytokine production. These findings highlight the fact that Rof and Lum likely prevents EAE by modulating Th1/Th2 response, and suggest its utility in the treatment of MS and other autoimmune diseases.

A Mandatory Role for STAT4 in IL-12 Induction of Mouse T Cell CCR5

IL-12 was recently shown to induce CCR5 on TCR-triggered mouse T cells. Considering that STAT4 is the most critical of IL-12 signaling molecules, this study investigated the role for STAT4 in the induction of CCR5 expression. IL-12R was induced by stimulation with anti-CD3 plus anti-CD28 mAb similarly on T cells from wild-type (WT) and STAT4-deficient (STAT4−/−) mice, but the levels of IL-12R induced on IFN-γ-deficient (IFN-γ−/−) T cells were lower compared with WT T cells. Exposure of TCR-triggered WT T cells to IL-12 induced CCR5 expression. In contrast, TCR-triggered STAT4−/− T cells failed to express CCR5 in response to IL-12. IL-12 stimulation induced detectable albeit reduced levels of CCR5 expression on IFN-γ−/− T cells. Addition of rIFN-γ to cultures of IFN-γ−/− T cells, particularly to cultures during TCR triggering resulted in restoration of CCR5 expression. However, CCR5 expression was not induced in STAT4−/− T cells by supplementation of rIFN-γ. These results indicate that for the induction of CCR5 on T cells, 1) STAT4 plays an indispensable role; 2) such a role is not substituted by simply supplementing rIFN-γ; and 3) IFN-γ amplifies CCR5 induction depending on the presence of STAT4.

SM934 Treated Lupus-Prone NZB×NZW F1 Mice by Enhancing Macrophage Interleukin-10 Production and Suppressing Pathogenic T Cell Development

BACKGROUND Artemisinin and its derivatives were reported to possess strong regulatory effects on inflammation and autoimmune diseases. This study was designed to examine the therapeutic effects and underlying mechanisms of SM934, a water-soluble artemisinin analogue, on lupus-prone female NZB × NZW F(1) mice. METHODOLOGY/PRINCIPAL FINDINGS NZB/W F(1) mice were treated orally with SM934 for 3 or 6 months respectively to investigate the effect on clinical manifestations and immunological correlates. To further explore the mechanisms of SM934, ovalbumin (OVA)-immunized or interferon (IFN)-γ-elicited C57BL/6 mice were used. In vivo, treatment with SM934 for 3 or 6 months significantly delayed the progression of glomerulonephritis and increased the survival rate of NZB/W F(1) mice. Clinical improvement was accompanied with decreased Th1-related anti-double-strand DNA (dsDNA) IgG2a and IgG3 Abs, serum interleukin (IL)-17, and increased Th2-related anti-dsDNA IgG1 Ab, serum IL-10 and IL-4. SM934 treatment also suppressed the accumulation of effector/memory T cells, induced the apoptosis of CD4(+) T cells, while enhancing the development of regulatory T cells in NZB/W F(1) mice. In addition, SM934 treatment promoted the IL-10 production of macrophages from NZB/W F(1) mice, OVA-immunized C57BL/6 mice and IFN-γ-elicited C57BL/6 mice. In vitro, SM934 enhanced IL-10 production from primary macrophages stimulated with IFN-γ. CONCLUSIONS/SIGNIFICANCE The results of this study demonstrated that artemisinin analogue SM934 had therapeutic effects on lupus-prone female NZB/W F(1) mice by inhibiting the pathogenic helper T cell development and enhancing anti-inflammatory cytokine IL-10 production.

A novel artemisinin derivative, 3-(12-beta-artemisininoxy) phenoxyl succinic acid (SM735), mediates immunosuppressive effects in vitro and in vivo.

AbstractAim:To study the immunosuppressive activity of SM735 {[3 -(12-β-artemisininoxy)] phenoxyl succinic acid}, a synthetic artemisinin derivative with nonsteroidal anti-inflammatory drug structure, with the aim of finding potential immunosuppressive agents.Methods:Concanavalin A (ConA), lipopolysaccharide (LPS), and mixed lymphocyte reaction (MLR), were used to induce the proliferation of splenocytes, and [3H]-thymidine incorporation was used to evaluate the proliferation of splenocytes. Cytokine production was promoted with ConA, LPS, or PMA plus ionomycin, and was detected with the enzyme-linked immunosorbent assay. Dinitrofluorobenzene (DNFB) and sheep red blood cells (SRBC) were used to induce delayed-type hypersensitivity and quantitative hemolysis of SRBC (QHS) mouse models, as criteria for the evaluation of in vivo immune activity.Results:SM735 strongly inhibited the proliferation of splenocytes induced by ConA, LPS, or MLR, with IC50 values of 0.33 μmol/L, 0.27 μmol/L, and 0.51 μmol/L, respectively. When compared with a CC50 value of 53.1 μmol/L, SM735 had a favorable safety range. SM735 dose-dependently inhibited proinflammatory cytokine production [including interleukins (IL)-12, interferon (IFN)-γ and IL-6] induced by LPS or PMA plus ionomycin. Upon ConA stimulation, SM735 suppressed IFN-γ in a dose-dependent manner, but did not affect IL-2 secretion. SM735 also strongly suppressed both T-cell-mediated delayed-type hypersensitivity (DTH) and B-cell-mediated QHS reactions.Conclusion:SM735 had strong immunosuppressive activity in vitro and in vivo, suggesting a potential role for SM735 as an immunosuppressive agent, and established the groundwork for further research onSM735.

(5R)-5-Hydroxytriptolide (LLDT-8), a novel triptolide derivative, prevents experimental autoimmune encephalomyelitis via inhibiting T cell activation

A novel triptolide derivative (5R)-5-hydroxytriptolide (LLDT-8) has been shown to have potent immunosuppressive activities. Here LLDT-8 was evaluated in experimental autoimmune encephalomyelitis (EAE), the model of multiple sclerosis (MS). LLDT-8 reduced the incidence and severity of EAE, which was associated with the inhibition of the MOG 35-55 lymphocyte recall response, anti-MOG 35-55 T cell responses, interleukin (IL)-2 and interferon (IFN)-gamma production. In vitro, LLDT-8 inhibited primary T cells proliferation, division, IL-2 and IFN-gamma production stimulated with anti-CD3/28. These findings highlight the fact that LLDT-8 prevents EAE by suppressing T cell proliferation and activation, with a potential for treatment of MS.