Interleukin-10 prevents experimental allergic encephalomyelitis in rats

CD11b+Ly-6C(hi) suppressive monocytes in experimental autoimmune encephalomyelitis

Innate immune cells may regulate adaptive immunity by balancing different lineages of T cells and providing negative costimulation. In addition, CD11b(+)Gr-1(+) myeloid-derived suppressor cells have been described in tumor, parasite infection, and severe trauma models. In this study, we observe that splenic CD11b(+) cells markedly increase after experimental autoimmune encephalomyelitis (EAE) immunization, and they suppress T cell proliferation in vitro. Although >80% of CD11b(+) cells express varying levels of Gr-1, only a small population of CD11b(+)Ly-6C(high) inflammatory monocytes (IMC) can efficiently suppress T cell proliferation and induce T cell apoptosis through the production of NO. IFN-gamma produced by activated T cells is essential to induce IMC suppressive function. EAE immunization increases the frequencies of IMC in the bone marrow, spleen, and blood, but not in the lymph nodes. At the peak of EAE, IMC represent approximately 30% of inflammatory cells in the CNS. IMC express F4/80 and CD93 but not CD31, suggesting that they are immature monocytes. Furthermore, IMC have the plasticity to up-regulate NO synthase 2 or arginase 1 expression upon different cytokine treatments. These findings indicate that CD11b(+)Ly-6C(high) IMC induced during EAE priming are powerful suppressors of activated T cells. Further understanding of suppressive monocytes in autoimmune disease models may have important clinical implications for human autoimmune diseases.

Abnormal Tr1 differentiation in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). In the recent years, accumulating evidence has supported an immunosuppressive role for regulatory T cells (Tregs). Most studies in the context of autoimmunity have focused on the defects of the CD4+CD25 high Tregs. However, we recently demonstrated an altered function of Tr1 Treg cells in MS, characterized by a lack of IL-10 secretion. Therefore, several major regulatory T cell defects are involved in human autoimmune disease. Hence, the induction of Tregs or the stimulation of Treg activity may be beneficial for the treatment of such diseases.

Endogenous interleukin-10 produced by antigen-irrelevant cells promotes the development of experimental murine allergic conjunctivitis

Interleukin (IL)-10 is known to act as an immunoregulatory cytokine in both T helper cell 1 (Th1)- and Th2-mediated immune responses. Here, we ask whether IL-10 regulates the development of experimental allergic conjunctivitis (EC), a Th2-mediated inflammatory disease. Wild-type (WT) and IL-10 knockout (IL-10 KO) mice were immunized with ragweed (RW) and then repeatedly challenged with RW in eye drops. Twenty-four hours after the final challenge, conjunctivas were harvested for histological analysis, while the blood and spleens were used to determine the RW-specific immunoglobulin levels in serum and proliferation or cytokine responses and splenocyte transfer, respectively. The IL-10 KO mice had significantly less severe EC (as determined by conjunctival eosinophil infiltration) than the WT mice and evinced greater RW-specific splenocyte proliferation and cytokine production. However, the RW-specific immunoglobulin levels of the two strains did not differ. When the splenocytes from RW-primed WT mice were transferred into IL-10 KO or WT mice, the IL-10 KO mice showed significantly less conjunctival eosinophil infiltration. In contrast, when the splenocytes from RW-primed IL-10 KO or WT mice were transferred into WT mice, both splenocyte populations generated equivalent severe EC. These data indicate that IL-10 does not serve as an immunoregulatory cytokine in the development of EC. Instead, it appears that IL-10 produced by antigen-irrelevant cells acts in the effector phase to promote the development of EC.

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.

Strain-specific differences in the effects of cyclosporin A and FK506 on the survival and regeneration of axotomized retinal ganglion cells in adult rats

The immune response can influence neuronal viability and plasticity after injury, effects differing in strains of rats with different susceptibility to autoimmune disease. We assessed the effects of i.p. injections of cyclosporin A (CsA) or FK506 on adult retinal ganglion cell (RGC) survival and axonal regeneration into peripheral nerve (PN) autografted onto the cut optic nerve of rats resistant (Fischer F344) or vulnerable (Lewis) to autoimmune disease. Circulating and tissue CsA and FK506 levels were similar in both strains. Three weeks after autologous PN transplantation the number of viable beta-III tubulin-positive RGCs was significantly greater in CsA- and FK506-treated F344 rats compared with saline-injected controls. RGC survival in Lewis rats was not significantly altered. In F344 rats, retrograde labeling of RGCs revealed that CsA or FK506 treatment significantly increased the number of RGCs that regenerated an axon into a PN autograft; however these agents had no beneficial effect on axonal regeneration in Lewis rats. PN grafts in F344 rats also contained comparatively more pan-neurofilament immunoreactive axons. In both strains, 3 weeks after transplantation CsA or FK506 treatment resulted in increased retinal macrophage numbers, but only in F344 rats was this increase significant. At this time-point PN grafts in both strains contained many macrophages and some T cells. T cell numbers in Lewis rats were significantly greater than in F344 animals. The increased RGC axonal regeneration seen in CsA- or FK506-treated F344 but not Lewis rats shows that modulation of immune responses after neurotrauma has complex and not always predictable outcomes.

Cytokine changes during interferon-beta therapy in multiple sclerosis: correlations with interferon dose and MRI response

We investigated serum (IL-10 and IL-12p70) and cellular cytokine levels (IL-10, IL-12p40, IL-12p70, IFN-gamma) in stimulated PBMC over 24 weeks in 15 relapsing-remitting multiple sclerosis (MS) patients randomized to receive once-weekly (qw) IFN-beta-1a 30 microg intramuscularly (IM) (n=8) or three-times-weekly (tiw) IFN-beta-1a 44 microg subcutaneously (SC) (n=7). Overall, IFN-beta treatment increased cellular IL-10 (p<0.01) levels and the ratios of cellular IL-10/IL-12p40 (p<0.01) and IL-10/IL-12p70 (p<0.02) while cellular IFN-gamma levels were reduced (p<0.01). Serum IL-10 levels were decreased in non-responders to therapy based on MRI-defined criteria (p<0.01) but did not change in responders over the course of treatment. In addition, non-responders demonstrated a decrease in serum IL-10/IL-12p70 ratio (p=0.031) and a decrease in cellular IL-12p70 (p<0.02). A decrease in cellular IFN-gamma was observed in responders (p=0.013). This is the first study that compares cytokine changes between the two IFN-beta regimes and demonstrates that serum IL-10 levels decrease in those patients who continue to have active MRI lesions while on interferon-beta therapy.

Anti-Ischemic Effect of Selectin Blocker Through Modulation of Tumor Necrosis Factor-α and Interleukin-10

BACKGROUND

Preliminary studies in our laboratories indicate that a recently discovered synthetic drug, TBC-1269, acts as a multiple selectin blocker and provides protection against tissue damage in rats that are subjected to severe liver ischemia/reperfusion. Here, we report that this effect is dose and time dependent, with its effects acting through the modulation of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70-80%) hepatic ischemia and 3 h of reperfusion were divided into eight groups (n=6/group): sham, ischemic control (IC), three groups of TBC-1269-treated animals at different concentrations (10, 20, 40, mg/kg) and another three groups of TBC-1269 given at 40 mg/kg at different times of administration: 15 min prereperfusion but after ischemia (no pretreatment), at the time of reperfusion, and at 15 min after reperfusion. The parameters measured at 3 h of reperfusion included liver function tests (alanine aminotransferase and aspartate aminotransferase), histopathology analysis and measurements using enzyme-linked immunosorbent assay in serum of TNF-alpha and IL-10. Statistical analysis included analysis of variance with P values of <0.05 for significance. Results were expressed as mean +/- SD.

RESULTS

The liver function tests showed statistically significant differences between the ischemic control group and both the sham group and the group treated with 40 mg/kg at the time of reperfusion (40@RP). These results correlated well with the histopathological analysis in that we found no difference in vacuolization, congestion, and necrosis between the 40@RP group and the sham group. The TNF-alpha and the IL-10 also reflected the protection observed in histopathology, with a decrease in TNF- alpha from the high levels observed in the IC (32 +/- 2.32 pg/mL) to a lower level of 8.5 +/- 4.04 mg observed in the 40@RP group, and an increment in the levels of the protective IL-10 from 2.8 +/- 2.9 pg/mL in the IC group versus 37.9 +/- 11.6 pg/mL in the 40@RP treated group (P<0.05). Lower doses and different times of administration of TBC-1269 did not show a protective effect. The IC group showed no difference in damage by histopathology or liver enzymes compared to the rest of the groups, except the 40@RP group.

CONCLUSION

In this work, we demonstrated that the small molecule multiple selectin inhibitor (TBC-1269) offered significant protection for the ischemic liver when given at 40 mg/kg at the time of perfusion. Lower doses and different times of administration did not show the optimal drug effect. The protection observed in the liver function tests (alanine aminotransferase and aspartate aminotransferase) and histopathology in this group was also reflected in the significant decrease in serum TNF-alpha and equally significant increase in serum protective IL-10.

Ryanodine receptor antagonism protects the ischemic liver and modulates TNF-alpha and IL-10

BACKGROUND

Dantrolene is a ryanodine receptor and intracellular calcium antagonist. The ryanodine receptor (RyR) Ca(2+) release channel mobilizes Ca(2+) from internal stores to support a variety of cellular functions, including the inflammatory response after ischemia and reperfusion. The pharmacological mechanism of dantrolene is associated with the inhibition of the release of Ca(2+) from the skeletal muscle sarcoplasmic reticulum (SR). We hypothesized that dantrolene could exert a protective effect in our model of liver ischemia and reperfusion by modulating TNF-alpha and IL-10.

MATERIAL AND METHODS

Mice subjected to 90 min of partial (70 to 80%) hepatic ischemia and 3 h of reperfusion were divided into five groups (n = 6/group): sham, ischemic control, and the dantrolene 1 mg/kg group studied at three times of administration: 15 min before reperfusion (DAN-PRE), at the time of reperfusion (DAN-RP), and 15 min after reperfusion (DAN-POS). The parameters measured at 3 h of reperfusion included serum liver function tests alanine aminotransferase (ALT) and aspartate aminotransferase (AST), TNF-alpha, and IL-10 in serum and liver histology.

RESULTS

It was demonstrated that the RyR intracellular calcium antagonist dantrolene offered the most significant protection for the ischemic liver when given before reperfusion and at the time of reperfusion. AST significantly differed between the control group and the DAN-PRE and DAN-RP groups (P < 0.05). ALT showed a statistically significant decrease in the DAN-PRE treated group and a decrease, although not significant, in the DAN-RP. Histological examination demonstrated a significant decrease in vacuolization in the same both groups (P < 0.05). Necrosis was significantly diminished when dantrolene was used at the time of reperfusion; congestion decreased in the same groups but without statistical significant difference. The levels of TNF-alpha were significantly decreased in the DAN-RP group. There was a decrease in TNF-alpha in the DAN-PRE group but not statistically significant. IL-10 reflected the protection observed in necrosis and vacuolization in the histopathology with an increment at the time of reperfusion (P < 0.05). DAN-POS did not exert a protective effect in ALT, AST, liver histology, or cytokine response.

CONCLUSION

For the first time the ryanodine receptor antagonist dantrolene offered significant functional and structural protection of the ischemic liver when given at the time for reperfusion and partial protection when given prereperfusion. RyR inhibition approach down-regulated the expression of TNF-alpha and induced an increment of the protective cytokine IL-10 when administered at the time of reperfusion. There was no protective effect of dantrolene after reperfusion.

Altered neuroantigen-specific cytokine secretion in a Th2 environment reduces experimental autoimmune encephalomyelitis

Activation of Th2 cells suppresses clinical experimental autoimmune encephalitis (EAE), demyelination and expression of genes associated with Th1-mediated inflammation. Despite both reduced central nervous system inflammation and IFN-gamma induced MHC class II expression by microglia, the composition of CNS infiltrates in Th2-protected mice were similar to mice with EAE. Analysis of the CNS infiltrating cells by flow cytometry suggests that protection did not correlate with abrogation of CD4+ T cell recruitment, preferential recruitment of donor Th2 cells or an increased frequency of CD25+ CD4+ T cells. By contrast, protection correlated with an increased frequency of neuroantigen-specific Th2 cells infiltrating the CNS. These data suggest that a peripheral Th2 cytokine environment influences both potential antigen presenting cells as well as recruitment and/or retention of neuroAg-specific Th2 CD4+ T cells.

Intrasplenic electro-transfer of IL-4 encoding plasmid DNA efficiently inhibits rat experimental allergic encephalomyelitis

Most of the previous studies in which cytokine DNA plasmids were delivered by systemic administration exhibited only marginal therapeutic effects, if any, in the EAE model. One strategy to overcome this limitation would be to determine the optimal delivery route leading to significant beneficial effects both in early (prophylactic) and late (therapeutic) treatments. To address this issue, we directly compared the effects of intrasplenic (i.s.) and intramuscular (i.m.) electro-transfer of interleukin-4 (IL-4) DNA in the rat experimental allergic encephalomyelitis (EAE) model. In the preventive experiment, rats received i.m. (25 or 150 microg) or i.s. (25 microg) administration of IL-4 DNA followed by in vivo electroporation the day before MBP immunization. In the late treatment experiment, rats were treated with i.m. (150 microg) or i.s. (25 microg) administration of IL-4 DNA with electroporation 10 days after MBP immunization. As a control the same amount of vector DNA was used. Macroscopic analysis indicated that the onset of moderate to severe EAE in rats treated with i.s. transfer of 25 microg of IL-4 DNA was prevented on a significant level compared with i.m. 25 microg of the IL-4 DNA transfer group or the control group in the preventive experiments. More importantly, i.s. transfer of 25 microg of IL-4 DNA considerably suppressed the severity of EAE in late treatment experiments while i.m. transfer of 150 microg of IL-4 DNA had little effect. The MBP-specific expression of IFN-gamma from stimulated splenocytes was considerably decreased by the i.s. IL-4 DNA transfer group both in the preventive and therapeutic experiments while i.m. transfer had this effect only in the preventive protocol. Histological analysis showed that spinal cord inflammation was considerably reduced in the i.s. IL-4 DNA transfer group. These data provide the first demonstration that i.s. electro-transfer of IL-4 DNA is more effective both in the prevention and modulation of EAE than i.m. transfer and that i.s. electro-gene transfer may present a new approach to cytokine therapy in autoimmune diseases.

Treatment of passive experimental autoimmune encephalomyelitis in SJL mice with a recombinant TCR ligand induces IL-13 and prevents axonal injury

The major goal of this study was to evaluate the efficacy and mechanism of a rTCR ligand (RTL) construct (I-A(s)/proteolipid protein (PLP)-139-151 peptide = RTL401) for treatment of SJL/J mice developing passive experimental autoimmune encephalomyelitis (EAE) that did not involve coimmunization with the highly inflammatory CFA. Our results demonstrated clearly that RTL401 was highly effective in treating passive EAE, with kinetics of recovery from disease very similar to treatment of actively induced EAE. The potent RTL401 treatment effect was reflected by a partial reduction of infiltrating mononuclear cells into CNS, minimal inflammatory lesions in spinal cord, and preservation of axons injured in vehicle-treated mice during the progression of EAE. Interestingly, in the absence of CFA, RTL401 treatment strongly enhanced production of the Th2 cytokine, IL-13, in spleen, blood, and spinal cord tissue, with variable effects on other Th1 and Th2 cytokines, and no significant effect on the Th3 cytokine, TGF-beta1, or on FoxP3 that is expressed by regulatory T cells. Moreover, pretreatment of PLP-139-151-specific T cells with RTL401 in vitro induced high levels of secreted IL-13, with lesser induction of other pro- and anti-inflammatory cytokines. Given the importance of IL-13 for protection against EAE, these data strongly implicate IL-13 as a dominant regulatory cytokine induced by RTL therapy. Pronounced IL-13 levels coupled with marked reduction in IL-6 levels secreted by PLP-specific T cells from blood after treatment of mice with RTL401 indicate that IL-13 and IL-6 may be useful markers for following effects of RTL therapy in future clinical trials in multiple sclerosis.

Adenovirus-mediated gene delivery of interleukin-10, but not transforming growth factor beta, ameliorates the induction of Graves' hyperthyroidism in BALB/c mice

Interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) are well known anti-inflammatory cytokines. We have studied the effect of adenovirus-mediated IL-10 and TGF-beta gene delivery on the induction of Graves' hyperthyroidism in our mouse model that involves repeated injections of adenovirus expressing the thyrotropin receptor A subunit (AdTSHR). We first constructed adenoviruses encoding the two cytokines (AdIL10 and AdTGF(beta)) and confirmed expression by in vitro infection of COS cells. Susceptible BALB/c mice were injected twice with AdTSHR alone or together with AdIL10 or AdTGF(beta), and bled two weeks after the second immunization. Significantly elevated serum thyroxine levels were seen in 26% of mice immunized with AdTSHR and AdIL10 versus 61% with AdTSHR alone. Levels of thyroid stimulating antibody, but not nonstimulating antibody, were also decreased, and TSHR-specific splenocyte secretion of interferon-gamma in recall assays was impaired in mice treated with AdIL10. In contrast, AdTGF(beta) had little effect on hyperthyroidism. Overall, our findings demonstrate that gene delivery of IL-10, but not TGF-beta, suppresses the induction of Graves' hyperthyroidism in a mouse model. However, the effect of IL-10 is less powerful than we observed previously with T helper type 2-inducers including adenovirus expressing IL-4, Shistosoma mansoni infection or alpha-galactosylceramide.

Interleukin-10 in murine metal-induced systemic autoimmunity

Systemic autoimmune diseases have a complicated and largely unknown aetiology and pathogenesis, but they are at least partly obeying the rules of an ordinary immune response. Cytokines are therefore important in the pathogenesis as demonstrated by the recent success in treating rheumatoid arthritis with anti-cytokine agents. The suppressive functions in the immune system have lately received much interest. One of the cytokines in focus in this respect is interleukin (IL)-10. We recently observed that in heavy-metal induced systemic autoimmunity, genetically resistant mice show a strong increase in IL-10 mRNA expression, which was not seen in susceptible mice. We have therefore examined the possible regulating effect of IL-10 on the induction and manifestation of systemic autoimmunity in this model. We took two approaches: a targeted mutation of the IL-10 gene in a strain resistant to heavy metal-induced autoimmunity, and treatment with recombinant IL-10 in the genetically susceptible A.SW strain during the induction of autoimmunity by metals. The wild-type C57BL/6 J (B6-WT) strain did not react with lymphoproliferation, polyclonal B cell activation, anti-nucleoar autoantibodies (ANoA) or tissue immune-complex (IC) deposits in response to inorganic mercury (Hg) or silver (Ag). However, serum IgG1 and IgE showed a modest increase during Hg treatment, while Ag caused a weak increase in IgE and IgG2a. The B6.129P2-Il10(tm1Cgn)/J strain (IL-10-deficient mice) did not develop antinucleolar antibodies (ANoA) during Hg treatment, but showed a higher median titre of homogeneous ANA compared with Hg-treated B6-WT mice. Both control and Hg-treated (but not Ag-treated) IL-10-deficient mice showed an increase in splenic weight and serum IgG1 compared with B6-WT control and Hg-treated mice. An early, significant increase in serum IgE was seen in Hg-treated IL-10-deficient and WT mice compared with the controls; the increase was 42- and sixfold, respectively. During ongoing intense treatment with rIL-10 in combination with Hg the susceptible A.SW mice showed a reduced development of ANoA and antichromatin antibodies, as well as serum IgE, compared with mice receiving Hg but not rIL-10. In conclusion, IL-10 suppresses several aspects of HgIA, but is not crucial for resistance to heavy metal-induced autoimmunity. Peroral silver treatment suppresses the spontaneous immune activation seen in IL-10-deficient mice.

IL-10-dependent infectious tolerance after the treatment of experimental allergic encephalomyelitis with redirected CD4+CD25+ T lymphocytes

How small numbers of CD4+CD25+ regulatory T cells suppress autoimmune responses in vivo is unclear. In this report we analyze the immunomodulatory activity of CD4+CD25+ T cells that are antigen-specifically redirected against myelin basic protein (MBP)89-101-specific autoreactive T cells by a MBP89-101-IA(s)-zeta chimeric receptor. We have previously shown that these redirected regulatory T cells are highly potent in treating a model autoimmune disease, experimental allergic encephalomyelitis. We show here that they have only limited effect in vivo on autoreactive T cell proliferation and therefore do not act by deleting or suppressing the expansion of pathologic effector cells. Rather, the redirected CD4+CD25+ T cells divert the pathologic T helper 1 self-specific T cell response to one characterized by high IL-10 and lower IL-4 production. Significantly, when isolated from the inducing CD4+CD25+ regulatory T cells, these self-specific T cells can independently suppress the autoreactive T cell response and experimental allergic encephalomyelitis development in an IL-10-dependent manner. These results provide evidence that CD4+CD25+ regulatory T cells can manipulate the adaptive immune response in vivo through the infectious induction of tolerance, specifically by promoting the formation of antigen-specific, IL-10-secreting regulatory T cells.

Co-infection with Trypanosoma brucei brucei prevents experimental autoimmune encephalomyelitis in DBA/1 mice through induction of suppressor APCs

The immune system has co-evolved with the infectious agents that challenge it, and in response pathogens have developed different mechanisms to subvert host immunity. A wealth of evidence suggests that infections are important components in the development of a functional immune system, and understanding the modulation of the host immune system by pathogens may offer new therapeutic strategies in a non-infectious setting. We investigated how infection with the protozoan parasite Trypanosoma brucei brucei (Tbb) modulates the autoimmune response to recombinant myelin oligodendrocyte glycoprotein (rMOG) in DBA/1 mice. Mice harbouring a Tbb infection did not develop experimental autoimmune encephalomyelitis (EAE) induced by immunization with rMOG in CFA, an animal model for the human autoimmune disease multiple sclerosis. Additionally, mice infected with the parasite at the time of immunization or 1 week later developed less severe EAE than uninfected controls. Protected mice displayed a markedly diminished rMOG-specific proliferation and IFNgamma production in lymph node cells and had correspondingly low titres of serum anti-rMOG IgG. Antigen-presenting cells (APCs) from spleens of Tbb-infected mice presented rMOG less efficiently to rMOG-specific T cells in vitro than did splenic APCs from uninfected mice and could also inhibit antigen-specific proliferation in control in vitro cultures. This suppressive effect is at least in part due to increased release of IL-10. Transfer of splenic APCs from Tbb-infected mice into mice immunized with rMOG-CFA 7 days previously abrogated disease significantly. These findings indicate that infections can prevent autoimmunity and that APCs might be used as immunomodulants.

IL-10-dependent suppression of experimental allergic encephalomyelitis by Th2-differentiated, anti-TCR redirected T lymphocytes

We previously showed that transgenically expressed chimeric Ag-MHC-zeta receptors can Ag-specifically redirect T cells against other T cells. When the receptor's extracellular Ag-MHC domain engages cognate TCR on an Ag-specific T cell, its cytoplasmic zeta-chain stimulates the chimeric receptor-modified T cell (RMTC). This induces effector functions such as cytolysis and cytokine release. RMTC expressing a myelin basic protein (MBP) 89-101-IAs-zeta receptor can be used therapeutically, Ag-specifically treating murine experimental allergic encephalomyelitis (EAE) mediated by MBP89-101-specific T cells. In initial studies, isolated CD8+ RMTC were therapeutically effective whereas CD4+ RMTC were not. We re-examine here the therapeutic potential of CD4+ RMTC. We demonstrate that Th2-differentiated, though not Th1-differentiated, CD4+ MBP89-101-IAs-zeta RMTC prevent actively induced or adoptively transferred EAE, and treat EAE even after antigenic diversification of the pathologic T cell response. The Th2 RMTC both Th2-deviate autoreactive T cells and suppress autoantigen-specific T cell proliferation. IL-10 is critical for the suppressive effects. Anti-IL-10R blocks RMTC-mediated modulation of EAE and suppression of autoantigen proliferation, as well as the induction of IL-10 production by autoreactive T cells. In contrast to IL-10, IL-4 is required for IL-4 production by, and hence Th2 deviation of autoreactive T cells, but not the therapeutic activity of the RMTC. These results therefore demonstrate a novel immunotherapeutic approach for the Ag-specific treatment of autoimmune disease with RMTC. They further identify an essential role for IL-10, rather than Th2-deviation itself, in the therapeutic effectiveness of these redirected Th2 T cells.

IL-4 and IL-10 modulate autoimmune haemolytic anaemia in NZB mice

New Zealand Black (NZB) mice spontaneously develop autoimmune haemolytic anaemia (AIHA). Here the effect of injecting NZB mice with plasmids encoding IL-4 (pIL-4) or IL-10 (pIL-10) on NZB disease was tested. Both constructs delayed the development of anaemia as judged by increased haematocrit values as compared with controls, but neither altered the IgG1 to IgG2 red blood cell (RBC) bound autoantibody levels. The increased haematocrit value was associated temporally with increased RBC bound IgG in NZB mice treated with pIL-10, but not pIL-4. By contrast, up-regulation of splenic macrophage FcgammaRIIb2 mRNA was associated temporally with increased haematocrit values in NZB mice given pIL-4. However, no such increase occurred in NZB mice that inhaled a peptide containing a dominant T-cell epitope, although this treatment is known to bias the autoimmune response towards Th2 and to reduce the severity of anaemia. It is considered that IL-4 treatment, in part, ameliorates NZB anaemia by increasing the expression of the inhibitory FcgammaRIIb2 and thereby reducing the capacity of splenic macrophages to phagocytose autoantibody coated RBC, but that this mechanism does not explain the beneficial effects of the inhaled peptide.

Brain microglia and blood-derived macrophages: molecular profiles and functional roles in multiple sclerosis and animal models of autoimmune demyelinating disease

Microglia and macrophages, one a brain-resident, the other a mostly hematogenous cell type, represent two related cell types involved in the brain pathology in multiple sclerosis and its autoimmune animal model, the experimental allergic encephalomyelitis. Together, they perform a variety of different functions: they are the primary sensors of brain pathology, they are rapidly recruited to sites of infection, trauma or autoimmune inflammation in experimental allergic encephalomyelitis and multiple sclerosis and they are competent presenters of antigen and interact with T cells recruited to the inflamed CNS. They also synthesise a variety of molecules, such as cytokines (TNF, interleukins), chemokines, accessory molecules (B7, CD40), complement, cell adhesion glycoproteins (integrins, selectins), reactive oxygen radicals and neurotrophins, that could exert a damaging or a protective effect on adjacent axons, myelin and oligodendrocytes. The current review will give a detailed summary on their cellular response, describe the different classes of molecules expressed and their attribution to the blood derived or brain-resident macrophages and then discuss how these molecules contribute to the neuropathology. Recent advances using chimaeric and genetically modified mice have been particularly telling about the specific, overlapping and nonoverlapping roles of macrophages and microglia in the demyelinating disease. Interestingly, they point to a crucial role of hematogenous macrophages in initiating inflammation and myelin removal, and that of microglia in checking excessive response and in the induction and maintenance of remission.

The effects of interferon-beta on interleukin-10 in multiple sclerosis patients

The incidence of the neuropathological lesions and the severity of the clinical symptoms in multiple sclerosis (MS) are correlated with the amount of the transferred autoreactive T cells. The balance between the T helper 1 (Th1) and T helper 2 (Th2) cytokine phenotypes may affect the activity of the disease in MS patients. Interleukin-10 (IL-10) is a cytokine secreted by Th2 cells. Thus, it has been thought that inducing IL-10 may have therapeutic effects in the treatment of MS patients. In this study, in order determine whether different types of prophylaxis change the secretion of IL-10, we measured the levels of IL-10 in relapsing-remitting type multiple sclerosis (RRMS) patients receiving interferon-beta 1b (IFN-beta 1b) or azathioprine (AZA). Our study consisted of RRMS patients (n=45) and healthy subjects (n=15) as control group. Patients were categorized into three groups as those receiving either IFN-beta 1b or AZA and those not receiving prophylaxis. Each group was compared with the control group. Serum IL-10 levels were determined using ELISA method. IL-10 levels of those receiving IFN-beta 1b were found to be significantly higher than that of other groups. These results support that the ability of inducing anti-inflammatory cytokine IL-10 plays a role in the clinical advantage of IFN-beta 1b in MS treatment.

Role of Microglia and Macrophages in Eae

Microglia and macrophages are related cell types that play an important role in the pathogenesis of MS and EAE. This chapters reviews the role of these cells in the normal brain and their contribution to inflammatory demyelinating disease, including their role in antigen presentation, co-stimulation, and production of cytokines and other inflammatory mediators

In situ detection of intracerebral cytokine expression after human brain contusion

The study was undertaken to analyze intracerebral expression of pro- and anti-inflammatory cytokines after traumatic brain injury (TBI) in man in order to compare the findings with previous experimental data regarding the pathogenesis of secondary brain injury. Contused brain tissue biopsies were obtained from 12 consecutive patients undergoing surgery for brain contusions 3 h to 5 days after trauma. Cytokine expression was analyzed by in situ hybridization and immunohistochemistry. In patients undergoing surgery less than 24 h after trauma, strong expression of both the pro-inflammatory cytokines interleukin (IL)-1-beta, IL-6 and interferon (IFN)-gamma and the anti-inflammatory cytokine IL-4 was detected. In patients undergoing surgery between 3 and 5 days after trauma, IL-4 expression was significantly lower (P < 0.05) compared to the patients operated early. IL-1-beta and IFN-gamma expression remained strong in comparison to IL-6 and IL-4 expression (P < 0.05). Immunohistochemistry for IL-1-beta confirmed that the protein was produced with a temporal and regional pattern that corresponded to in situ hybridization results. The study provides in situ data on intracerebral cytokine expression after contusion in the clinical setting. Strong intracerebral cytokine expression occurs in the perilesional zone both in the early and the delayed phase after traumatic brain injury in humans. The temporal regulation of pro- and anti-inflammatory cytokines differs which reveals different therapeutic windows for pharmacological intervention.

mRNA expression of proinflammatory cytokines in mouse CNS correlates with replication rate of semliki forest virus but not with the strain of viral proteins

Tissue expression in viral infection of immunological effector molecules may depend on virus structure or replication or both. We analyzed cytokine mRNA expression in the central nervous system (CNS) of Balb/c mice during viral infection with Semliki Forest virus (SFV) clones, which varied either in structure or virulence or both. Highly neurovirulent SFV4 effectively induced IFN-gamma, TNF-alpha, IL-6 and TGF-beta, but its avirulent derivative V4-opal with nsP3 arginine-476 to opal mutation, elicited only weak induction of these cytokines. Structurally different, avirulent rA774, obtained by cloning from avirulent SFV A7(74) strain, did not induce synthesis of proinflammatory Th1 or Th2 cytokines in murine CNS, but increased synthesis of TGF-beta transcripts. In contrast, structurally identical but moderately virulent rA774-arg virus with sense codon at opal position in nsP3, markedly stimulated synthesis of IFN-gamma, TNF-alpha, and IL-10 transcripts, without, however, reaching the levels elicited by lethal SFV4. The rA774-arg clone was more potent in attracting peripheral immune cells into the CNS than the completely avirulent strains. In conclusion, induction of proinflammatory cytokine mRNA in the CNS by SFV infection seemed to correlate with the rate of viral replication and was not significantly influenced by the virus envelope or nonstructural protein primary structure. The results also have relevance for development of CNS gene therapy vectors as SFV4 and A774 display differences in CNS infection characteristics.

Peroxisome proliferator-activated receptor alpha agonists as therapy for autoimmune disease

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily. PPAR gamma ligands, which include the naturally occurring PG metabolite 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), as well as thiazolidinediones, have been shown to have anti-inflammatory activity. The PPAR alpha agonists, gemfibrozil, ciprofibrate, and fenofibrate, have an excellent track history as oral agents used to treat hypertriglyceridemia. In the present study, we demonstrate that these PPAR alpha agonists can increase the production of the Th2 cytokine, IL-4, and suppress proliferation by TCR transgenic T cells specific for the myelin basic protein Ac1-11, as well as reduce NO production by microglia. Oral administration of gemfibrozil and fenofibrate inhibited clinical signs of experimental autoimmune encephalomyelitis. More importantly, gemfibrozil was shown to shift the cytokine secretion of human T cell lines by inhibiting IFN-gamma and promoting IL-4 secretion. These results suggest that PPAR alpha agonists such as gemfibrozil and fenofibrate, may be attractive candidates for use in human inflammatory conditions such as multiple sclerosis.

Schistosoma mansoniand α-Galactosylceramide: Prophylactic Effect of Th1 Immune Suppression in a Mouse Model of Graves’ Hyperthyroidism

Graves' hyperthyroidism, an organ-specific autoimmune disease mediated by stimulatory thyrotropin receptor (TSHR) autoantibodies, has been considered a Th2-dominant disease. However, recent data with mouse Graves' models are conflicting. For example, we recently demonstrated that injection of BALB/c mice with adenovirus coding the TSHR induced Graves' hyperthyroidism characterized by mixed Th1 and Th2 immune responses against the TSHR, and that transient coexpression of the Th2 cytokine IL-4 by adenovirus skewed Ag-specific immune response toward Th2 and suppressed disease induction. To gain further insight into the relationship between immune polarization and Graves' disease, we evaluated the effect of Th2 immune polarization by helminth Schistosoma mansoni infection and alpha-galactosylceramide (alpha-GalCer), both known to bias the systemic immune response to Th2, on Graves' disease. S. mansoni infection first induced mixed Th1 and Th2 immune responses to soluble worm Ags, followed by a Th2 response to soluble egg Ags. Prior infection with S. mansoni suppressed the Th1-type anti-TSHR immune response, as demonstrated by impaired Ag-specific IFN-gamma secretion of splenocytes and decreased titers of IgG2a subclass anti-TSHR Abs, and also prevented disease development. Similarly, alpha-GalCer suppressed Ag-specific splenocyte secretion of IFN-gamma and prevented disease induction. However, once the anti-TSHR immune response was fully induced, S. mansoni or alpha-GalCer was ineffective in curing disease. These data support the Th1 theory in Graves' disease and indicate that suppression of the Th1-type immune response at the time of Ag priming may be crucial for inhibiting the pathogenic anti-TSHR immune response.

Local adeno-associated virus-mediated interleukin 10 gene transfer has disease-modifying effects in a murine model of Sjögren's syndrome

Female nonobese diabetic (NOD) mice develop spontaneous autoimmune sialadenitis and loss of salivary flow, and are a widely used model of Sjögren's syndrome. We examined the feasibility of local salivary gland immunomodulatory gene delivery to alter these sequelae in NOD mice. We constructed recombinant adeno-associated virus (rAAV) vectors encoding either human interleukin 10 (rAAVhIL-10) or beta-galactosidase (rAAVLacZ, control vector). Mice received rAAVhIL-10 or rAAVLacZ by retrograde submandibular ductal instillation either at age 8 weeks (early, before onset of sialadenitis), or at 16 weeks (late, after onset of sialadenitis). As a systemic treatment control, separate mice received intramuscular delivery of rAAVhIL-10 at each time point. Both submandibular and intramuscular delivery of vector led to low circulating levels of hIL-10. After submandibular administration of rAAVhIL-10, salivary flow rates at 20 weeks for both the early and late treatment groups were significantly higher than for both rAAVLacZ-administered and untreated mice. Systemic delivery of rAAVhIL-10 led to improved salivary flow in the late treatment group. Inflammatory infiltrates in submandibular glands, however, were significantly reduced only in mice receiving rAAVhIL-10 locally in the salivary gland compared with mice receiving this vector intramuscularly, or rAAVLacZ or no treatment. In addition, after submandibular rAAVhIL-10 delivery, NOD mice exhibited significantly lower blood glucose, and higher serum insulin, levels than all other groups, indicating some systemic benefit of this treatment. These studies show that expression of hIL-10 by rAAV vectors can have disease-modifying effects in the salivary glands of NOD mice, and suggest that local immunomodulatory gene transfer may be useful for managing the salivary gland pathology in Sjögren's syndrome.

RDP58, a novel immunomodulatory peptide, ameliorates clinical signs of disease in the Lewis rat model of acute experimental autoimmune encephalomyelitis

The therapeutic value of a novel immunomodulatory peptide, RDP58, was investigated in the acute experimental autoimmune encephalomyelitis (EAE) model of Multiple Sclerosis (MS). RDP58 is a 10-amino acid peptide with two major activities: (i) inhibition of inflammatory TH1 cytokines such as TNFalpha, IFNgamma, and IL12 and (ii) up-regulation of heme oxygenase-1 (HO-1) expression. Experiments in which EAE-induced Lewis rats exhibit an acute monophasic episode of disease demonstrated that a single intracerebroventricular injection of RDP58 is effective in preventing clinical signs of disease. The therapeutic effect on disease activity was observed at all pre-onset administration times and at all doses tested. Consistent with disease activity in vivo, RDP58-treated animals had reduced cellular infiltration within the spinal cord along with decreased TNFalpha expression levels. The data in this proof of concept study support the premise that RDP58, as a platform molecule, may be a promising new therapeutic intervention in autoimmune and inflammatory diseases.

The role of interleukin 10 in the pathogenesis and potential treatment of skin diseases

Interleukin 10 (IL-10) is a key cytokine produced by a multitude of immune effector cells and possesses distinct regulatory effects on immune functioning in the skin. In this article we report the current understanding of the immunobiology of IL-10 and identify the role of IL-10 in cutaneous infection as well as in autoimmune and neoplastic processes. We reviewed the literature to examine the function of IL-10 in different cutaneous disorders. IL-10 can influence and potentially treat T1/T2 differentiation, antigen-presenting cell functioning, antigen-presenting cell-mediated T-cell activation, and T-cell, B-cell, and mast cell growth and differentiation that is aberrant in various disease processes. The literature consensus is that the multitude of effects of IL-10 contribute to the pathogenesis of different skin disorders. In certain circumstances IL-10 could represent novel therapeutic approaches to treating cutaneous diseases.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should be acquainted with the role of IL-10 in many infectious diseases, autoimmune skin disease, inflammatory processes, and malignancy. Its possible role in the resolution of various skin diseases should be better understood.

Induction of IL-10 in rat peritoneal macrophages and dendritic cells by glatiramer acetate

Glatiramer acetate (GLAT) is a mixture of basic polypeptides that have been shown to suppress experimental autoimmune encephalomyelitis (EAE). As Copaxone, GLAT is approved for the treatment of relapsing-remitting multiple sclerosis (MS). Different immunomechanisms have been suggested to contribute to the beneficial effects of GLAT which rely on blockade of MHC class II molecules or cross-recognition with myelin basic protein (MBP). Because GLAT could also inhibit experimental autoimmunity not related to myelin proteins, we searched for additional, less-restricted immunomodulatory actions of GLAT. Using freshly isolated resident peritoneal macrophages from naive Lewis rats, it is shown that GLAT profoundly modulates cytokine secretion of the cells. In unseparated macrophages (MPhi) and MPhi of low density, GLAT enhanced constitutive and LPS-induced production of interleukin 10 (IL-10) while LPS-induced synthesis of tumor necrosis factor-alpha (TNF-alpha) was dose-dependently suppressed by GLAT. Although both basic proteins GLAT and MBP facilitated adherence of MPhi, MBP had opposite effects on cytokine production suggesting unique properties of GLAT. In contrast to MPhi, peritoneal mast cells produced only little amounts of cytokines. The inductive effect of GLAT on IL-10 production by antigen-presenting cells was also observed in bone marrow-derived rat dendritic cells (DCs) which, unlike MPhi, were not suppressed in their production of TNF-alpha. Induction of IL-10 in different antigen-presenting cells is a new immunomodulatory mechanism of GLAT. In part, it goes along with the inhibition of TNF-alpha and may be a common basis for the known beneficial effects of GLAT on various cellular autoimmune responses including MS.

IFN-inducible protein 10/CXC chemokine ligand 10-independent induction of experimental autoimmune encephalomyelitis

In multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), autoaggressive T cells traffic into the CNS and induce disease. Infiltration of these pathogenic T cells into the CNS has been correlated with the expression of the chemokine IFN-inducible protein (IP)10/CXC chemokine ligand (CXCL)10, a chemoattractant for activated T cells, and its receptor CXCR3, in the CNS of both MS patients and mice with EAE. In the present study, we report that targeted deletion of IP-10 did not diminish the expression, severity, or histopathology of EAE induced by active immunization with 100 micro g of myelin oligodendrocyte glycoprotein peptide (MOG)p35-55. However, we found that IP-10-deficient mice had a lower threshold for expression of disease compared with wild-type littermates. EAE induced by immunization with 5 micro g of MOGp35-55 resulted in more severe disease characterized by a greater number of CNS lesions and infiltrating mononuclear cells in IP-10-deficient mice compared with wild-type controls. IP-10-deficient mice immunized with MOGp35-55 demonstrated increased levels of IFN-inducible T cell alpha-chemokine/CXCL11 mRNA in the CNS and decreased levels of monokine induced by IFN-gamma/CXCL9 mRNA in draining lymph nodes, suggesting differential compensation for loss of IP-10 in lymphoid vs parenchymal tissue compartments. EAE in IP-10-deficient mice induced by low-dose immunization was associated with enhanced Ag-specific Th1 responses in the draining lymph node, which corresponded with diminished lymph node TGF-beta1 expression. Our data demonstrated that IP-10 was not required for the trafficking of pathogenic T cells into the CNS in EAE but played an unexpected role in determining the threshold of disease susceptibility in the periphery.

Theiler's virus infection: a model for multiple sclerosis

Both genetic background and environmental factors, very probably viruses, appear to play a role in the etiology of multiple sclerosis (MS). Lessons from viral experimental models suggest that many different viruses may trigger inflammatory demyelinating diseases resembling MS. Theiler's virus, a picornavirus, induces in susceptible strains of mice early acute disease resembling encephalomyelitis followed by late chronic demyelinating disease, which is one of the best, if not the best, animal model for MS. During early acute disease the virus replicates in gray matter of the central nervous system but is eliminated to very low titers 2 weeks postinfection. Late chronic demyelinating disease becomes clinically apparent approximately 2 weeks later and is characterized by extensive demyelinating lesions and mononuclear cell infiltrates, progressive spinal cord atrophy, and axonal loss. Myelin damage is immunologically mediated, but it is not clear whether it is due to molecular mimicry or epitope spreading. Cytokines, nitric oxide/reactive nitrogen species, and costimulatory molecules are involved in the pathogenesis of both diseases. Close similarities between Theiler's virus-induced demyelinating disease in mice and MS in humans, include the following: major histocompatibility complex-dependent susceptibility; substantial similarities in neuropathology, including axonal damage and remyelination; and paucity of T-cell apoptosis in demyelinating disease. Both diseases are immunologically mediated. These common features emphasize the close similarities of Theiler's virus-induced demyelinating disease in mice and MS in humans.

Molecular mechanisms of interleukin-10-mediated inhibition of NF-kappaB activity: a role for p50

Nuclear factor kappa B (NF-kappaB) is a transcription factor pivotal for the development of inflammation. A dysregulation of NF-kappaB has been shown to play an important role in many chronic inflammatory diseases including rheumatoid arthritis, inflammatory bowel disease and psoriasis. Although classical NF-kappaB, a heterodimer composed of the p50 and p65 subunits, has been well studied, little is known about gene regulation by other hetero- and homodimeric forms of NF-kappaB. While p65 possesses a transactivation domain, p50 does not. Indeed, p50/p50 homodimers have been shown to inhibit transcriptional activity. We have recently shown that Interleukin-10 exerts its anti-inflammatory activity in part through the inhibition of NF-kappaB by blocking IkappaB kinase activity and by inhibiting NF-kappaB already found in the nucleus. Since the inhibition of nuclear NF-kappaB could not be explained by an increase of nuclear IkappaB, we sought to further investigate the mechanisms involved in the inhibition of NF-kappaB by IL-10. We show here that IL-10 selectively induced nuclear translocation and DNA-binding of p50/p50 homodimers in human monocytic cells. TNF-alpha treatment led to a strong translocation of p65 and p50, whereas pretreatment with IL-10 followed by TNF-alpha blocked p65 translocation but did not alter the strong translocation of p50. Furthermore, macrophages of p105/p50-deficient mice exhibited a significantly decreased constitutive production of MIP-2alpha and IL-6 in comparison to wild type controls. Surprisingly, IL-10 inhibited high constitutive levels of these cytokines in wt macrophages but not in p105/p50 deficient cells. Our findings suggest that the selective induction of nuclear translocation and DNA-binding of the repressive p50/p50 homodimer is an important anti-inflammatory mechanism utilized by IL-10 to repress inflammatory gene transcription.

Cytokine shifts and tolerance in experimental autoimmune encephalomyelitis

Cytokines play an important role in the pathogenesis of both multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Effective treatments for both diseases have been shown to alter cytokines in the central nervous system and in activated mononuclear cells. EAE is an animal model that mimics many aspects of multiple sclerosis, and has been widely used to study the mechanisms of disease and therapeutic approaches to multiple sclerosis. Cytokines play an important role in regulation of disease expression in EAE, and in tolerance to disease induction. In this review, we will summarize the current findings on the role of cytokine shifts in the induction of tolerance in EAE. In addition, we will discuss modulation of EAE by altered expression of members of the cytokineregulated Jak/STAT intracellular signaling pathway.

The multifaceted relationship between IL-10 and adaptive immunity: putting together the pieces of a puzzle

Interleukin-10 (IL-10) is a pleiotropic cytokine that modulates the function of several adaptive immunity-related cells. Although generally considered an immunosuppressive molecule, IL-10 possesses immunostimulatory properties in several in vitro and in vivo models. These very different outcomes are believed to depend upon experimental conditions, the dominant immune effector mediating a given immune response, the timing of IL-10 production/administration, and IL-10 dose and/or location of expression. In the present work, we review the current knowledge regarding IL-10 activity on adaptive immunity related cells, emphasize new insights on IL-10 molecular/cellular targets, and summarize the available data on the relationship between IL-10 and some pathological conditions (e.g. infectious diseases, autoimmunity, allergy, cancer and transplantation) involving adaptive immunity.

Effect of intranasal administration of semliki forest virus recombinant particles expressing reporter and cytokine genes on the progression of experimental autoimmune encephalomyelitis

We have initiated studies to determine the feasibility of employing the Semliki Forest virus (SFV) expression system as a central nervous system (CNS) vector. We investigated the effects of infecting Balb/c mice intranasally (i.n.) with recombinant SFV particles expressing the enhanced green fluorescent protein (EGFP) reporter gene. EGFP expression was detected by fluorescence microscopy in the olfactory bulb as early as 1 day postinfection. No pathological changes were associated with infection. Viral RNA could be detected in the olfactory mucosa only, whereas fluorescence was detected in axons in the olfactory bulb, indicating that only the expressed protein was present. A vector expressing interleukin 10 (IL-10) was constructed and shown to induce good cytokine expression in cultured cells. IL-10 expression in the nasal passage and olfactory bulb of infected mice was enhanced following i.n. administration of such particles. Mice induced for experimental autoimmune encephalomyelitis (EAE) were treated i.n. with vectors expressing EGFP and IL-10 and with empty vector. The EGFP-expressing and empty vectors were found to exacerbate EAE, whereas that expressing IL-10 ameliorated EAE. It is concluded that the mice showed a significant biological response when treated i.n. with recombinant SFV particles and that such particles administered by the i.n. route have potential as a noninvasive vector for protein delivery to the CNS.

Role of interferon-gamma and nitric oxide in the neuropathogenesis of avirulent Semliki Forest virus infection

Semliki Forest virus (SFV) infection of mice provides a useful model for the analysis of viral neuropathogenesis. In this study, the roles of interferon (IFN)-gamma and nitric oxide (NO) in the pathogenesis of SFV infection were assessed using mice deficient in inducible nitric oxide synthase (iNOS-/-), an enzyme important in the production of NO, and mice deficient in IFN-gamma receptor (IFN-gammaR-/-). Gene-knockout and wildtype mice were infected intranasally with the avirulent A7 strain of SFV and neuropathological lesions were correlated with levels of IFN-gamma, tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 in the olfactory bulbs and frontal cortex. Lesions in IFN-gammaR-/- mice were characterized by higher levels of neuronal necrosis than in wildtype mice. The higher levels of neuronal necrosis were associated with increased levels of SFV antigen in neurones and increased numbers of macrophages and B cells. Relative differences in the severity of demyelination between IFN-gammaR-/- and wildtype mice were not detected. Similar levels of neuronal necrosis and SFV antigen labelling occurred in iNOS-/- mice and wildtype mice and levels of demyelination and macrophage infiltration in the iNOS-/- mice were lower than those in the wildtype strain. A rapid, but transient increase in the concentration of IFN-gamma was demonstrated in the frontal cortex of all infected mice samples. IL-10 levels in the frontal cortex and olfactory bulbs of SFV-infected iNOS-/- mice exceeded those present in the wildtype mice. This study, taken with our previous reports, provides further evidence that type 1 T cell responses are important in the control of brain viral clearance and the prevention of neuronal necrosis, but not in the development of demyelination.

Autoimmune diseases as the loss of active "self-control"

Converging experimental evidence indicates that the clinical expression of autoimmunity is under the control of T cell-mediated immunoregulatory circuits. Several types of suppressor T cells have been described. Some of them are closely dependent upon cytokines such as TH2 cells and Tr1 cells. Others appear to rely more on cell-cell contact (such as CD25+ CD62L+ T cells), although some cytokines, notably TGF-beta, may be involved in their growth or their mode of action. It is tempting to separate suppressor cells that appear spontaneously, such as CD25+ T cells and NKT cells (innate immunoregulation), from those that are only observed after antigen administration, such as TH2 cells and Tr1 cells (adaptive immunoregulation). The role of these diverse cell types in the control of the onset or the progression of autoimmune diseases is likely, but still a matter of debate. A central question is to determine whether immune dysregulation precedes the burst of pathogenic autoimmunity.

Interleukin-10 therapy--review of a new approach

Interleukin (IL)-10 is an important immunoregulatory cytokine produced by many cell populations. Its main biological function seems to be the limitation and termination of inflammatory responses and the regulation of differentiation and proliferation of several immune cells such as T cells, B cells, natural killer cells, antigen-presenting cells, mast cells, and granulocytes. However, very recent data suggest IL-10 also mediates immunostimulatory properties that help to eliminate infectious and noninfectious particles with limited inflammation. Numerous investigations, including expression analyses in patients, in vitro and animal experiments suggest a major impact of IL-10 in inflammatory, malignant, and autoimmune diseases. So IL-10 overexpression was found in certain tumors as melanoma and several lymphomas and is considered to promote further tumor development. Systemic IL-10 release is a powerful tool of the central nervous system to prevent hyperinflammatory processes by activation of the neuro-endocrine axis following acute stress reactions. In contrast, a relative IL-10 deficiency has been observed and is regarded to be of pathophysiological relevance in certain inflammatory disorders characterized by a type 1 cytokine pattern such as psoriasis. Recombinant human IL-10 has been produced and is currently being tested in clinical trials. This includes rheumatoid arthritis, inflammatory bowel disease, psoriasis, organ transplantation, and chronic hepatitis C. The results are heterogeneous. They give new insight into the immunobiology of IL-10 and suggest that the IL-10/IL-10 receptor system may become a new therapeutic target.

Gene therapy in autoimmune, demyelinating disease of the central nervous system

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS), where suspected autoimmune attack causes nerve demyelination and progressive neurodegeneration and should benefit from both anti-inflammatory and neuroprotective strategies. Although neuroprotection strategies are relatively unexplored in MS, systemic delivery of anti-inflammatory agents to people with MS has so far been relatively disappointing. This is most probably because of the limited capacity of these molecules to enter the target tissue, because of exclusion by the blood-brain barrier. The complex natural history of MS also means that any therapeutic agents will have to be administered long-term. Gene therapy offers the possibility of site-directed, long-term expression, and is currently being preclinically investigated in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. While some immune effects may be targeted in the periphery using DNA vaccination, strategies both viral and nonviral are being developed to target agents into the CNS either via direct delivery or using the trafficking properties of cell-carrier systems. Targeting of leucocyte activation, cytokines and nerve growth factors have shown some promising benefit in animal EAE systems, the challenge will be their application in clinical use.

Proinflammatory effects of exogenously administered IL-10 in experimental autoimmune orchitis

We studied the effects of exogenously administered recombinant murine interleukin (IL)-10 on the development of experimental autoimmune orchitis (EAO) in C3H/He mice. IL-10 significantly augments histological signs of EAO when administered for 6 consecutive days from days 15 to 20 after primary immunisations with testicular germ cells. These data demonstrate that IL-10, in addition to its well-known antiinflammatory property, also has proinflammatory functions capable of up-regulating testicular immunoinflammatory processes in vivo.

Regional and temporal expression patterns of interleukin-10, interleukin-10 receptor and adhesion molecules in the rat spinal cord during chronic relapsing EAE

Adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mediate leukocyte infiltration into the CNS, in experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). Because exogenous interleukin-10 (IL-10) inhibits ICAM-1 and VCAM-1 expression and clinical EAE, we hypothesize that endogenous IL-10 signaling may suppress expression of adhesion molecules. In a rat model of chronic relapsing EAE, expression levels of IL-10 and its receptor (IL-10R1), ICAM-1 and VCAM-1 mRNA in the spinal cord are markedly increased, whereas levels of IL-10 mRNA remain relatively low. The temporal pattern of mRNA and protein expression showed marked differences between spinal cord levels. During relapse, IL-10, IL-10R1, ICAM-1, VCAM-1 mRNA levels and neurological scores show positive correlations. We conclude that endogenous IL-10 is not a crucial factor inhibiting adhesion molecule expression in this model.

Therapeutic approaches in multiple sclerosis: lessons from failed and interrupted treatment trials

The therapy for multiple sclerosis (MS) has changed dramatically over the past decade. Recent immunobiological findings and current pathophysiological concepts together with advances in biotechnology, improvements in clinical trial design and development of magnetic resonance imaging have led to a variety of evaluable therapeutic approaches in MS. However, in contrast to the successfully introduced and established immunomodulatory therapies (e.g. interferon-beta and glatiramer acetate), there have been a remarkable number of therapeutic failures as well. Despite convincing immunological concepts, impressive data from animal models and promising results from phase I/II studies, the drugs and strategies investigated showed no benefit or even turned out to have unexpectedly severe adverse effects. Although to date there is no uniformly accepted model for MS, there is agreement on the significance of inflammatory events mediated by autoreactive T cells in the CNS. These can be modified therapeutically at the individual steps of a hypothetical pathogenetic cascade. Crucial corners like: the prevalence and peripheral activation of CNS-autoreactive T cells in the periphery;adhesion and penetration of T cells into the CNS;local activation and proliferation and;de- and remyelination processes can be targeted through their putative mediators. Like a 'specificity pyramid', therapeutic approaches therefore cover from general immunosuppression up to specific targeting of T-cell receptor peptide major histocompatibility (MHC) complex. We discuss in detail clinical MS trials that failed or were discontinued for other reasons. These trials include cytokine modulators [tumour necrosis factor (TNF)-alpha antagonists, interleukin-10, interleukin-4, transforming growth factor-beta2], immunosuppressive agents (roquinimex, gusperimus, sulfasalazine, cladribine), inducers of remyelination [intravenous immunoglobulins (IVIg)], antigen-derived therapies [oral tolerance, altered peptide ligands (APL), MHC-Peptide blockade], T cell and T-cell receptor directed therapies (T cell vaccination, T-cell receptor peptide vaccination), monoclonal antibodies against leucocyte differentiation molecules (anti-CD3, anti-CD4), and inactivation of circulating T cells (extracorporeal photopheresis). The main conclusions that can be drawn from these 'negative' experiences are as follows. Theoretically promising agents may paradoxically increase disease activity (lenercept, infliximab), be associated with unforeseen adverse effects (e.g. roquinimex) or short-term favourable trends may reverse with prolonged follow-up (e.g. sulfasalzine). One should not be too enthusiastic about successful trials in animal models (TNFalpha blockers; oral tolerance; remyelinating effect of IVIg) nor be irritated by non-scientific media hype (deoxyspergualine; bone marrow transplantation). More selectivity can imply less efficacy (APL, superselective interventions like T-cell receptor vaccination) and antigen-related therapies can stimulate rather than inhibit encephalitogenic cells. Failed strategies are of high importance for a critical revision of assumed immunopathological mechanisms, their neuroimaging correlates, and for future trial design. Since failed trials add to our growing understanding of multiple sclerosis, 'misses' are nearly as important to the scientific process as the 'hits'.

Effects of combination therapy of beta-interferon 1a and prednisone on serum immunologic markers in patients with multiple sclerosis

Beta-interferon (beta-IFN) has a proven treatment effect on relapsing-remitting multiple sclerosis (MS), presumably through its regulatory properties on T-cell activation and cytokine production. This paper examines whether combination therapy of beta-IFN with prednisone would enhance immunoregulatory effects of beta-IFN by measuring serum levels of selected proinflammatory cytokines and soluble T-cell activation markers associated with MS. The selected markers were analyzed in MS patients treated with beta-IFN alone (n = 22) and beta-IFN combined with a low daily dose of prednisone (n = 33), as compared with those in 27 healthy controls at baseline and at a three-month interval for one year. The study confirmed that beta-IFN treatment inhibited serum levels of tumor necrosis factor-alpha (TNFalpha) and intracellular adhesion molecule-1 (ICAM-1) in patients with MS. However, combination therapy did not significantly enhance the inhibitory effect of beta-IFN treatment on the production of TNFalpha, interleukin (IL)-12, IL-2R, and ICAM-1, while the addition of prednisone antagonized the effect of beta-IFN on up-regulation of IL-10 and soluble CD95. No difference in the occurrence of binding antibodies to beta-IFN was found between the two treatment groups. The findings are important for the understanding of the role of combination therapy in the treatment of MS.

Synergistic inhibitory activities of interleukin-10 and dexamethasone on human CD4+ T cells

BACKGROUND

We have previously demonstrated that interleukin (IL)-10 synergizes with dexamethasone (Dex) in inhibiting proliferation of human T cells, stimulated in an antigen-presenting cell (APC)-dependent manner. Because IL-10 effectively inhibits APC accessory functions, the synergism could have been a result of its effect on APC. We then investigated the effects of Dex and IL-10 on T-cell subpopulations, stimulated in an APC-independent manner.

METHODS

CD4 and CD8 T cells were stimulated with anti-CD3, with or without Dex and IL-10, alone or in combination. Proliferation, glucocorticoid (GC) receptor binding, anti-CD3-induced tyrosine phosphorylation, IL-2 production, and expression of IL-2 receptor alpha, beta, and gamma chains were evaluated. The pharmacologic interactions were analyzed using the isobole method.

RESULTS

IL-10 synergized with Dex in inhibiting CD4 but not CD8 T-cell proliferation. The synergism was not associated with modifications of GC receptor number or affinity, nor with modifications of anti-CD3-induced tyrosine phosphorylation. IL-10 synergized with Dex in inhibiting IL-2 production and increased Dex inhibitory effect on the expression of the IL-2 receptor alpha chain, which is up-regulated by CD3 stimulation and IL-2. Only Dex inhibited the beta and gamma chain expression, which, interestingly, is not up-regulated by IL-2. IL-2, as well as IL-7 and IL-15, reversed the effects of IL-10 but not those of Dex.

CONCLUSIONS

IL-10 synergizes with Dex in inhibiting CD4 T-cell proliferation. Its synergizing effect is mediated by the inhibition of IL-2 production. Dex exerts additional activities, such as the inhibition of beta and gamma chain expression. Therefore, IL-10 could be useful for the enhancement of GC-based immunosuppressive therapies.

Intranasal peptide-induced peripheral tolerance: the role of IL-10 in regulatory T cell function within the context of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a T cell-mediated autoimmune disease commonly employed as a model for multiple sclerosis. Extensive studies have demonstrated that EAE may be prevented or ameliorated by the intranasal administration of soluble peptides representing encephalitogenic epitopes. There is increasing evidence that this peptide administration may function via the generation of regulatory cells. The mechanism of action of these cells remains controversial and it seems likely that it may vary between experimental models. At present the majority of work on regulatory cells has centred on characterising naturally occurring regulators, or those generated artificially ex vivo, and less is known about induced regulatory cells produced following peptide administration. This report aims to briefly outline the evidence for the existence of natural regulatory T cells and to introduce the sub-types of induced regulatory T cells now recognised. In several of these regulatory cell systems investigated to date, interleukin-10 (IL-10) has been shown to be important in cell function. This has not been directly investigated in a model employing peptide therapy to induce peripheral tolerance, hence the purpose of this study was to investigate the role of IL-10 in the generation of these regulatory cells. This work has employed both a TCR transgenic mouse system, for predominantly in vitro studies of cell function, and an IL-10 knock-out mouse strain to investigate in vivo disease protection. The results summarised in this report demonstrate that IL-10 is fundamentally important in the generation of disease protection following intranasal peptide therapy.

The role of interleukin-10 in autoimmune disease: systemic lupus erythematosus (SLE) and multiple sclerosis (MS)

Interleukin-10 (IL-10) is an immunoregulatory cytokine that plays a crucial role in inflammatory and immune reactions. It has potent anti-inflammatory and immunosuppressive activities on myeloid cell functions which forms a solid basis for its use in acute and chronic inflammatory diseases. Here, we discuss the role of IL-10 in autoimmune diseases and examine its beneficial effects in cellular-based autoimmune diseases such as multiple sclerosis (MS) or its involvement in humoral-based autoimmune diseases such as systemic lupus erythematosus (SLE). Inhibition of the immune stimulatory activities of IL-10 may provide novel approaches in the treatment of humoral autoimmune diseases, infectious diseases and cancer.