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Blocking GluR2-GAPDH ameliorates experimental autoimmune encephalomyelitis.

Zhai D, Lee FH, D'Souza C, Su P, Zhang S, Jia Z, Zhang L, Wong AH, Liu F - Ann Clin Transl Neurol (2015)

Bottom Line: We found that protein complex composed of the GluR2 subunit of AMPA receptors and GAPDH (glyceraldehyde-3-phosphate dehydrogenase) was present at significantly higher levels in postmortem tissue from MS patients and in EAE mice, an animal model for MS.This peptide greatly improves neurological function in EAE mice, reduces neuron death, rescues demyelination, increases oligodendrocyte survival, and reduces axonal damage in the spinal cords of EAE mice.More importantly, our peptide has no direct suppressive effect on naive T-cell responses or basal neurotransmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Centre for Addiction and Mental Health Toronto, Ontario, Canada, M5T 1R8.

ABSTRACT

Objective: Multiple sclerosis (MS) is the most common disabling neurological disease of young adults. The pathophysiological mechanism of MS remains largely unknown and no cure is available. Current clinical treatments for MS modulate the immune system, with the rationale that autoimmunity is at the core of MS pathophysiology.

Methods: Experimental autoimmune encephalitis (EAE) was induced in mice with MOG35-55 and clinical scoring was performed to monitor signs of paralysis. EAE mice were injected intraperitoneally with TAT-fusion peptides daily from day 10 until day 30 after immunization, and their effects were measured at day 17 or day 30.

Results: We report a novel target for the development of MS therapy, which aimed at blocking glutamate-mediated neurotoxicity through targeting the interaction between the AMPA (2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl) propanoic acid) receptor and an interacting protein. We found that protein complex composed of the GluR2 subunit of AMPA receptors and GAPDH (glyceraldehyde-3-phosphate dehydrogenase) was present at significantly higher levels in postmortem tissue from MS patients and in EAE mice, an animal model for MS. Next, we developed a peptide that specifically disrupts the GluR2 -GAPDH complex. This peptide greatly improves neurological function in EAE mice, reduces neuron death, rescues demyelination, increases oligodendrocyte survival, and reduces axonal damage in the spinal cords of EAE mice. More importantly, our peptide has no direct suppressive effect on naive T-cell responses or basal neurotransmission.

Interpretation: The GluR2 -GAPDH complex represents a novel therapeutic target for the development of medications for MS that work through a different mechanism than existing treatments.

No MeSH data available.


Related in: MedlinePlus

TAT-G-Gpep treatment diminishes the activated immune response in experimental autoimmune encephalitis (EAE) mice. (A) EAE mice in all groups showed an increase in CD4+ T-cell proliferation when presented with 10 μg/mL of MOG. TAT-G-Gpep administration significantly reduced this proliferative response. **P < 0.01; ***P < 0.001. (B) Representative images of Iba1-immunolabeled macrophages/microglia in sham, TAT-G-Gpep-Sc, nontreated and TAT-G-Gpep-treated mouse spinal cords. Scale bar = 100 μm. (C) Quantification of the number of Iba1+ cells in the dorsal and ventral horns revealed significantly more macrophages/microglia residing in scrambled peptide, nontreated and peptide-treated mice when compared to sham. Peptide treatment significantly reduced the amount Iba1+ cells when compared to scrambled peptide or nontreated mice. All data are shown as mean ± SEM; **P < 0.01 versus sham; +P < 0.01. (D, E) TAT-G-Gpep treatment in EAE mice resulted in a significant reduction in IL-17 (D) and IFN-γ (E) levels when compared to nontreated or TAT-G-Gpep-Sc treated mice. *P < 0.05.
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fig04: TAT-G-Gpep treatment diminishes the activated immune response in experimental autoimmune encephalitis (EAE) mice. (A) EAE mice in all groups showed an increase in CD4+ T-cell proliferation when presented with 10 μg/mL of MOG. TAT-G-Gpep administration significantly reduced this proliferative response. **P < 0.01; ***P < 0.001. (B) Representative images of Iba1-immunolabeled macrophages/microglia in sham, TAT-G-Gpep-Sc, nontreated and TAT-G-Gpep-treated mouse spinal cords. Scale bar = 100 μm. (C) Quantification of the number of Iba1+ cells in the dorsal and ventral horns revealed significantly more macrophages/microglia residing in scrambled peptide, nontreated and peptide-treated mice when compared to sham. Peptide treatment significantly reduced the amount Iba1+ cells when compared to scrambled peptide or nontreated mice. All data are shown as mean ± SEM; **P < 0.01 versus sham; +P < 0.01. (D, E) TAT-G-Gpep treatment in EAE mice resulted in a significant reduction in IL-17 (D) and IFN-γ (E) levels when compared to nontreated or TAT-G-Gpep-Sc treated mice. *P < 0.05.

Mentions: EAE has been regarded as a primarily CD4+ T-cell-mediated condition. Current clinical treatment for MS targets the inflammatory process through immunosuppression.2,23,24 Thus, it is important to determine the effects of the TAT-G-Gpep peptide on CD4+ T-cell activation and proliferation. We first determined the effects of the TAT-G-Gpep peptide on the immune system of EAE mice in vivo using T-cell recall response assays. Since we showed that the motor function of EAE mice treated with TAT-G-Gpep peptide improved considerably by day 17 after immunization (Fig.1F), we examined CD4+ T-cell proliferation in draining lymph node cells of EAE mice at that time. Cells were CFSE-labeled and restimulated with MOG35-55in vitro for 3 days. As seen in Figure4A, CD4+ T-cells from EAE mice without treatment or treated with control peptide proliferated vigorously upon MOG35-55 restimulation. In contrast, CD4+ T-cells from EAE mice treated with TAT-G-Gpep had a significantly reduced proliferative response to MOG35-55 restimulation, suggesting that TAT-G-Gpep can dampen an already activated immune response. As MS is closely associated with inflammation, we then tested whether TAT-G-Gpep affects microglial/macrophage recruitment on mouse spinal cord sections against ionized calcium-binding adapter molecule 1 Iba1 in all groups and quantified Iba1-immunolabeled microglia/macrophages in the dorsal and ventral horn regions. As shown in Figure4B and C, the number of Iba1+ cells was significantly increased in EAE mice without treatment or treated with control peptide when compare to sham group, while TAT-G-Gpep administration significantly decreased Iba1-cells in EAE mice. Consistent with this, levels of both IFN-γ and IL-17, two key proinflammatory cytokines involved in the pathogenesis of EAE, were reduced in supernatants of EAE mice treated with TAT-G-G peptide. Levels in supernatants from EAE mice treated with control peptide were similar to those from untreated EAE mice. These results reinforce our finding that TAT-G-Gpep is able to modulate the inflammatory response in the EAE model.


Blocking GluR2-GAPDH ameliorates experimental autoimmune encephalomyelitis.

Zhai D, Lee FH, D'Souza C, Su P, Zhang S, Jia Z, Zhang L, Wong AH, Liu F - Ann Clin Transl Neurol (2015)

TAT-G-Gpep treatment diminishes the activated immune response in experimental autoimmune encephalitis (EAE) mice. (A) EAE mice in all groups showed an increase in CD4+ T-cell proliferation when presented with 10 μg/mL of MOG. TAT-G-Gpep administration significantly reduced this proliferative response. **P < 0.01; ***P < 0.001. (B) Representative images of Iba1-immunolabeled macrophages/microglia in sham, TAT-G-Gpep-Sc, nontreated and TAT-G-Gpep-treated mouse spinal cords. Scale bar = 100 μm. (C) Quantification of the number of Iba1+ cells in the dorsal and ventral horns revealed significantly more macrophages/microglia residing in scrambled peptide, nontreated and peptide-treated mice when compared to sham. Peptide treatment significantly reduced the amount Iba1+ cells when compared to scrambled peptide or nontreated mice. All data are shown as mean ± SEM; **P < 0.01 versus sham; +P < 0.01. (D, E) TAT-G-Gpep treatment in EAE mice resulted in a significant reduction in IL-17 (D) and IFN-γ (E) levels when compared to nontreated or TAT-G-Gpep-Sc treated mice. *P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig04: TAT-G-Gpep treatment diminishes the activated immune response in experimental autoimmune encephalitis (EAE) mice. (A) EAE mice in all groups showed an increase in CD4+ T-cell proliferation when presented with 10 μg/mL of MOG. TAT-G-Gpep administration significantly reduced this proliferative response. **P < 0.01; ***P < 0.001. (B) Representative images of Iba1-immunolabeled macrophages/microglia in sham, TAT-G-Gpep-Sc, nontreated and TAT-G-Gpep-treated mouse spinal cords. Scale bar = 100 μm. (C) Quantification of the number of Iba1+ cells in the dorsal and ventral horns revealed significantly more macrophages/microglia residing in scrambled peptide, nontreated and peptide-treated mice when compared to sham. Peptide treatment significantly reduced the amount Iba1+ cells when compared to scrambled peptide or nontreated mice. All data are shown as mean ± SEM; **P < 0.01 versus sham; +P < 0.01. (D, E) TAT-G-Gpep treatment in EAE mice resulted in a significant reduction in IL-17 (D) and IFN-γ (E) levels when compared to nontreated or TAT-G-Gpep-Sc treated mice. *P < 0.05.
Mentions: EAE has been regarded as a primarily CD4+ T-cell-mediated condition. Current clinical treatment for MS targets the inflammatory process through immunosuppression.2,23,24 Thus, it is important to determine the effects of the TAT-G-Gpep peptide on CD4+ T-cell activation and proliferation. We first determined the effects of the TAT-G-Gpep peptide on the immune system of EAE mice in vivo using T-cell recall response assays. Since we showed that the motor function of EAE mice treated with TAT-G-Gpep peptide improved considerably by day 17 after immunization (Fig.1F), we examined CD4+ T-cell proliferation in draining lymph node cells of EAE mice at that time. Cells were CFSE-labeled and restimulated with MOG35-55in vitro for 3 days. As seen in Figure4A, CD4+ T-cells from EAE mice without treatment or treated with control peptide proliferated vigorously upon MOG35-55 restimulation. In contrast, CD4+ T-cells from EAE mice treated with TAT-G-Gpep had a significantly reduced proliferative response to MOG35-55 restimulation, suggesting that TAT-G-Gpep can dampen an already activated immune response. As MS is closely associated with inflammation, we then tested whether TAT-G-Gpep affects microglial/macrophage recruitment on mouse spinal cord sections against ionized calcium-binding adapter molecule 1 Iba1 in all groups and quantified Iba1-immunolabeled microglia/macrophages in the dorsal and ventral horn regions. As shown in Figure4B and C, the number of Iba1+ cells was significantly increased in EAE mice without treatment or treated with control peptide when compare to sham group, while TAT-G-Gpep administration significantly decreased Iba1-cells in EAE mice. Consistent with this, levels of both IFN-γ and IL-17, two key proinflammatory cytokines involved in the pathogenesis of EAE, were reduced in supernatants of EAE mice treated with TAT-G-G peptide. Levels in supernatants from EAE mice treated with control peptide were similar to those from untreated EAE mice. These results reinforce our finding that TAT-G-Gpep is able to modulate the inflammatory response in the EAE model.

Bottom Line: We found that protein complex composed of the GluR2 subunit of AMPA receptors and GAPDH (glyceraldehyde-3-phosphate dehydrogenase) was present at significantly higher levels in postmortem tissue from MS patients and in EAE mice, an animal model for MS.This peptide greatly improves neurological function in EAE mice, reduces neuron death, rescues demyelination, increases oligodendrocyte survival, and reduces axonal damage in the spinal cords of EAE mice.More importantly, our peptide has no direct suppressive effect on naive T-cell responses or basal neurotransmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Centre for Addiction and Mental Health Toronto, Ontario, Canada, M5T 1R8.

ABSTRACT

Objective: Multiple sclerosis (MS) is the most common disabling neurological disease of young adults. The pathophysiological mechanism of MS remains largely unknown and no cure is available. Current clinical treatments for MS modulate the immune system, with the rationale that autoimmunity is at the core of MS pathophysiology.

Methods: Experimental autoimmune encephalitis (EAE) was induced in mice with MOG35-55 and clinical scoring was performed to monitor signs of paralysis. EAE mice were injected intraperitoneally with TAT-fusion peptides daily from day 10 until day 30 after immunization, and their effects were measured at day 17 or day 30.

Results: We report a novel target for the development of MS therapy, which aimed at blocking glutamate-mediated neurotoxicity through targeting the interaction between the AMPA (2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl) propanoic acid) receptor and an interacting protein. We found that protein complex composed of the GluR2 subunit of AMPA receptors and GAPDH (glyceraldehyde-3-phosphate dehydrogenase) was present at significantly higher levels in postmortem tissue from MS patients and in EAE mice, an animal model for MS. Next, we developed a peptide that specifically disrupts the GluR2 -GAPDH complex. This peptide greatly improves neurological function in EAE mice, reduces neuron death, rescues demyelination, increases oligodendrocyte survival, and reduces axonal damage in the spinal cords of EAE mice. More importantly, our peptide has no direct suppressive effect on naive T-cell responses or basal neurotransmission.

Interpretation: The GluR2 -GAPDH complex represents a novel therapeutic target for the development of medications for MS that work through a different mechanism than existing treatments.

No MeSH data available.


Related in: MedlinePlus