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Coupling of peripheral tolerance to endogenous interleukin 10 promotes effective modulation of myelin-activated T cells and ameliorates experimental allergic encephalomyelitis.

Legge KL, Min B, Bell JJ, Caprio JC, Li L, Gregg RK, Zaghouani H - J. Exp. Med. (2000)

Bottom Line: Although promising results have been obtained from these studies that define mechanisms of T cell modulation, efficacy, practicality, and toxicity, concerns remain unsolved, thereby justifying further investigations to define alternatives for effective downregulation of aggressive T cells.Indeed, it is shown that animals with ongoing active experimental allergic encephalomyelitis dramatically reduce the severity of their paralysis when treated with adjuvant free aggregated Ig-PLP1.Moreover, IL-10 displays bystander antagonism on unrelated autoreactive T cells, allowing for reversal of disease involving multiple epitopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA.

ABSTRACT
Several immune-based approaches are being considered for modulation of inflammatory T cells and amelioration of autoimmune diseases. The most recent strategies include simulation of peripheral self-tolerance by injection of adjuvant free antigen, local delivery of cytokines by genetically altered T cells, and interference with the function of costimulatory molecules. Although promising results have been obtained from these studies that define mechanisms of T cell modulation, efficacy, practicality, and toxicity, concerns remain unsolved, thereby justifying further investigations to define alternatives for effective downregulation of aggressive T cells. In prior studies, we demonstrated that an immunoglobulin (Ig) chimera carrying the encephalitogenic proteolipid protein (PLP)1 peptide corresponding to amino acid sequence 139-151 of PLP, Ig-PLP1, is presented to T cells approximately 100-fold better than free PLP1. Here, we demonstrate that aggregation endows Ig-PLP1 with an additional feature, namely, induction of interleukin (IL)-10 production by macrophages and dendritic cells, both of which are antigen-presenting cells (APCs). These functions synergize in vivo and drive effective modulation of autoimmunity. Indeed, it is shown that animals with ongoing active experimental allergic encephalomyelitis dramatically reduce the severity of their paralysis when treated with adjuvant free aggregated Ig-PLP1. Moreover, IL-10 displays bystander antagonism on unrelated autoreactive T cells, allowing for reversal of disease involving multiple epitopes. Therefore, aggregated Ig-PLP1 likely brings together a peripheral T cell tolerance mechanism emanating from peptide presentation by APCs expressing suboptimal costimulatory molecules and IL-10 bystander suppression to drive a dual-modal T cell modulation system effective for reversal of autoimmunity involving several epitopes and diverse T cell specificities.

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Neutralization of Ig-PLP1–induced endogenous IL-10 restores severity of paralysis. (a) SJL/J mice (eight per group) were induced for EAE with 100 μg PLP1, and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg agg Ig-PLP1 plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-PLP1 + anti-IL-10); 300 μg agg Ig-PLP1 plus 500 μg rat IgG (agg Ig-PLP1 + rat IgG); 300 μg agg Ig-W (agg Ig-W); or 300 μg agg Ig-W plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-W + anti-IL-10). All the injections were done intraperitoneally in PBS. (b) Exogenous IL-10 synergizes with sol Ig-PLP1 to reduce the severity of EAE. Groups of mice (eight per group) were induced for EAE with 100 μg PLP1 and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg sol Ig-PLP1 (sol Ig-PLP1); 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg sol Ig-PLP1 plus 400 U recombinant IL-10 (sol Ig-PLP1 + IL-10); or 300 μg agg Ig-W (agg Ig-W).
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Figure 8: Neutralization of Ig-PLP1–induced endogenous IL-10 restores severity of paralysis. (a) SJL/J mice (eight per group) were induced for EAE with 100 μg PLP1, and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg agg Ig-PLP1 plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-PLP1 + anti-IL-10); 300 μg agg Ig-PLP1 plus 500 μg rat IgG (agg Ig-PLP1 + rat IgG); 300 μg agg Ig-W (agg Ig-W); or 300 μg agg Ig-W plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-W + anti-IL-10). All the injections were done intraperitoneally in PBS. (b) Exogenous IL-10 synergizes with sol Ig-PLP1 to reduce the severity of EAE. Groups of mice (eight per group) were induced for EAE with 100 μg PLP1 and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg sol Ig-PLP1 (sol Ig-PLP1); 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg sol Ig-PLP1 plus 400 U recombinant IL-10 (sol Ig-PLP1 + IL-10); or 300 μg agg Ig-W (agg Ig-W).

Mentions: As IL-10 has been defined to antagonize Th1 cytokines 55 and possibly interfere with inflammatory functions, we postulated that the effectiveness of agg Ig-PLP1 in T cell modulation and reversal of disease lies on inadequate peptide presentation by APCs expressing minimal costimulatory molecules and the inhibitory function of IL-10 produced by such APCs. To test this hypothesis, mice were induced for EAE with PLP1 peptide, and when the signs of paralysis became apparent, the mice were given agg Ig-PLP1 together with anti–IL-10 antibody and assessed for reduction in disease severity. The results presented in Fig. 8 a indicate that the severity of paralysis was restored when in vivo IL-10 was neutralized by the anti–IL-10 antibody. In fact, mice treated with agg Ig-PLP1 alone had a mean maximal clinical score of 1.1 ± 0.5, whereas the mice injected with both agg Ig-PLP1 and anti–IL-10 antibody had a score of 3.0 ± 0.3, which is comparable to the 3.3 ± 0.3 (P > 0.23) score seen in mice treated with agg Ig-W. Furthermore, control mice given agg Ig-PLP1 together with rat IgG, instead of anti–IL-10 antibody, did not restore disease severity and had a mean maximal score of 1.6 ± 0.2. Injection of anti–IL-10 antibody together with agg Ig-W neither reduced nor exacerbated the severity of disease. These results indicate that agg Ig-PLP1–induced IL-10 plays a significant role in controlling disease severity, and that for the effects of IL-10 to occur, a specific interaction between APCs and the target T cells is required. In support of this statement is the observation that treatment with sol Ig-PLP1 plus exogenous IL-10 reduces the severity of paralysis to the same extent as agg Ig-PLP1 (Fig. 8 b). Sol Ig-PLP1, which does not induce detectable levels of IL-10, ameliorates the disease slightly with a mean maximal score of 2.5 ± 0.3, whereas sol Ig-PLP1 together with exogenous IL-10 further reduces the disease to a mean maximal clinical score of 1.1 ± 0.3, which is comparable to the 1.1 ± 0.5 score obtained with mice treated with agg Ig-PLP1. Furthermore, for endogenous IL-10 to modulate the disease, a physical bridging of the APCs to the T cells seems to be required. This conclusion is drawn from the observation that treatment of diseased mice with a mixture of agg Ig-W and free PLP1 peptide, instead of agg Ig-PLP1, did not reduce the severity of disease (Fig. 9). Overall, effective T cell downregulation requires physical interaction between IL-10–producing APCs and the target pathogenic T cell. The likely explanation for this requirement is that IL-10 as a paracrine cytokine needs to be in close proximity to T cells in order to achieve antagonism.


Coupling of peripheral tolerance to endogenous interleukin 10 promotes effective modulation of myelin-activated T cells and ameliorates experimental allergic encephalomyelitis.

Legge KL, Min B, Bell JJ, Caprio JC, Li L, Gregg RK, Zaghouani H - J. Exp. Med. (2000)

Neutralization of Ig-PLP1–induced endogenous IL-10 restores severity of paralysis. (a) SJL/J mice (eight per group) were induced for EAE with 100 μg PLP1, and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg agg Ig-PLP1 plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-PLP1 + anti-IL-10); 300 μg agg Ig-PLP1 plus 500 μg rat IgG (agg Ig-PLP1 + rat IgG); 300 μg agg Ig-W (agg Ig-W); or 300 μg agg Ig-W plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-W + anti-IL-10). All the injections were done intraperitoneally in PBS. (b) Exogenous IL-10 synergizes with sol Ig-PLP1 to reduce the severity of EAE. Groups of mice (eight per group) were induced for EAE with 100 μg PLP1 and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg sol Ig-PLP1 (sol Ig-PLP1); 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg sol Ig-PLP1 plus 400 U recombinant IL-10 (sol Ig-PLP1 + IL-10); or 300 μg agg Ig-W (agg Ig-W).
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Figure 8: Neutralization of Ig-PLP1–induced endogenous IL-10 restores severity of paralysis. (a) SJL/J mice (eight per group) were induced for EAE with 100 μg PLP1, and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg agg Ig-PLP1 plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-PLP1 + anti-IL-10); 300 μg agg Ig-PLP1 plus 500 μg rat IgG (agg Ig-PLP1 + rat IgG); 300 μg agg Ig-W (agg Ig-W); or 300 μg agg Ig-W plus 500 μg rat anti–mouse IL-10 antibody, 2A5 (agg Ig-W + anti-IL-10). All the injections were done intraperitoneally in PBS. (b) Exogenous IL-10 synergizes with sol Ig-PLP1 to reduce the severity of EAE. Groups of mice (eight per group) were induced for EAE with 100 μg PLP1 and on days 9, 13, and 17 were given intraperitoneally in PBS 300 μg sol Ig-PLP1 (sol Ig-PLP1); 300 μg agg Ig-PLP1 (agg Ig-PLP1); 300 μg sol Ig-PLP1 plus 400 U recombinant IL-10 (sol Ig-PLP1 + IL-10); or 300 μg agg Ig-W (agg Ig-W).
Mentions: As IL-10 has been defined to antagonize Th1 cytokines 55 and possibly interfere with inflammatory functions, we postulated that the effectiveness of agg Ig-PLP1 in T cell modulation and reversal of disease lies on inadequate peptide presentation by APCs expressing minimal costimulatory molecules and the inhibitory function of IL-10 produced by such APCs. To test this hypothesis, mice were induced for EAE with PLP1 peptide, and when the signs of paralysis became apparent, the mice were given agg Ig-PLP1 together with anti–IL-10 antibody and assessed for reduction in disease severity. The results presented in Fig. 8 a indicate that the severity of paralysis was restored when in vivo IL-10 was neutralized by the anti–IL-10 antibody. In fact, mice treated with agg Ig-PLP1 alone had a mean maximal clinical score of 1.1 ± 0.5, whereas the mice injected with both agg Ig-PLP1 and anti–IL-10 antibody had a score of 3.0 ± 0.3, which is comparable to the 3.3 ± 0.3 (P > 0.23) score seen in mice treated with agg Ig-W. Furthermore, control mice given agg Ig-PLP1 together with rat IgG, instead of anti–IL-10 antibody, did not restore disease severity and had a mean maximal score of 1.6 ± 0.2. Injection of anti–IL-10 antibody together with agg Ig-W neither reduced nor exacerbated the severity of disease. These results indicate that agg Ig-PLP1–induced IL-10 plays a significant role in controlling disease severity, and that for the effects of IL-10 to occur, a specific interaction between APCs and the target T cells is required. In support of this statement is the observation that treatment with sol Ig-PLP1 plus exogenous IL-10 reduces the severity of paralysis to the same extent as agg Ig-PLP1 (Fig. 8 b). Sol Ig-PLP1, which does not induce detectable levels of IL-10, ameliorates the disease slightly with a mean maximal score of 2.5 ± 0.3, whereas sol Ig-PLP1 together with exogenous IL-10 further reduces the disease to a mean maximal clinical score of 1.1 ± 0.3, which is comparable to the 1.1 ± 0.5 score obtained with mice treated with agg Ig-PLP1. Furthermore, for endogenous IL-10 to modulate the disease, a physical bridging of the APCs to the T cells seems to be required. This conclusion is drawn from the observation that treatment of diseased mice with a mixture of agg Ig-W and free PLP1 peptide, instead of agg Ig-PLP1, did not reduce the severity of disease (Fig. 9). Overall, effective T cell downregulation requires physical interaction between IL-10–producing APCs and the target pathogenic T cell. The likely explanation for this requirement is that IL-10 as a paracrine cytokine needs to be in close proximity to T cells in order to achieve antagonism.

Bottom Line: Although promising results have been obtained from these studies that define mechanisms of T cell modulation, efficacy, practicality, and toxicity, concerns remain unsolved, thereby justifying further investigations to define alternatives for effective downregulation of aggressive T cells.Indeed, it is shown that animals with ongoing active experimental allergic encephalomyelitis dramatically reduce the severity of their paralysis when treated with adjuvant free aggregated Ig-PLP1.Moreover, IL-10 displays bystander antagonism on unrelated autoreactive T cells, allowing for reversal of disease involving multiple epitopes.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA.

ABSTRACT
Several immune-based approaches are being considered for modulation of inflammatory T cells and amelioration of autoimmune diseases. The most recent strategies include simulation of peripheral self-tolerance by injection of adjuvant free antigen, local delivery of cytokines by genetically altered T cells, and interference with the function of costimulatory molecules. Although promising results have been obtained from these studies that define mechanisms of T cell modulation, efficacy, practicality, and toxicity, concerns remain unsolved, thereby justifying further investigations to define alternatives for effective downregulation of aggressive T cells. In prior studies, we demonstrated that an immunoglobulin (Ig) chimera carrying the encephalitogenic proteolipid protein (PLP)1 peptide corresponding to amino acid sequence 139-151 of PLP, Ig-PLP1, is presented to T cells approximately 100-fold better than free PLP1. Here, we demonstrate that aggregation endows Ig-PLP1 with an additional feature, namely, induction of interleukin (IL)-10 production by macrophages and dendritic cells, both of which are antigen-presenting cells (APCs). These functions synergize in vivo and drive effective modulation of autoimmunity. Indeed, it is shown that animals with ongoing active experimental allergic encephalomyelitis dramatically reduce the severity of their paralysis when treated with adjuvant free aggregated Ig-PLP1. Moreover, IL-10 displays bystander antagonism on unrelated autoreactive T cells, allowing for reversal of disease involving multiple epitopes. Therefore, aggregated Ig-PLP1 likely brings together a peripheral T cell tolerance mechanism emanating from peptide presentation by APCs expressing suboptimal costimulatory molecules and IL-10 bystander suppression to drive a dual-modal T cell modulation system effective for reversal of autoimmunity involving several epitopes and diverse T cell specificities.

Show MeSH
Related in: MedlinePlus