Therapeutic vaccine for acute and chronic motor neuron diseases: implications for amyotrophic lateral sclerosis

Abstract

Therapeutic vaccination with Copaxone (glatiramer acetate, Cop-1) protects motor neurons against acute and chronic degenerative conditions. In acute degeneration after facial nerve axotomy, the number of surviving motor neurons was almost two times higher in Cop-1-vaccinated mice than in nonvaccinated mice, or in mice injected with PBS emulsified in complete Freund's adjuvant (P < 0.05). In mice that express the mutant human gene Cu/Zn superoxide dismutase G93A (SOD1), and therefore simulate the chronic human motor neuron disease amyotrophic lateral sclerosis, Cop-1 vaccination prolonged life span compared to untreated matched controls, from 211 +/- 7 days (n = 15) to 263 +/- 8 days (n = 14; P < 0.0001). Our studies show that vaccination significantly improved motor activity. In line with the experimentally based concept of protective autoimmunity, these findings suggest that Cop-1 vaccination boosts the local immune response needed to combat destructive self-compounds associated with motor neuron death. Its differential action in CNS autoimmune diseases and neurodegenerative disorders, depending on the regimen used, allows its use as a therapy for either condition. Daily administration of Cop-1 is an approved treatment for multiple sclerosis. The protocol for non-autoimmune neurodegenerative diseases such as amyotrophic lateral sclerosis, remains to be established by future studies.

Figure 1

Rescue of motor neurons by Cop-1 administered after facial nerve axotomy. Retrograde neuronal labeling after injection of FluoroGold into the whiskerpad showed no differences in the localization or amount of motor neurons in the intact facial nucleus between mice immunized with PBS in CFA (A) and mice injected with Cop-1 in CFA (C). In contrast, the lesioned facial nucleus in control mice pretreated with PBS in CFA contained significantly fewer labeled motor neurons than that of the lesioned facial nucleus in mice pretreated with Cop-1 in CFA (B vs. D).

Figure 2

Cop-1 vaccination protects RGCs against glutamate toxicity. (A) C57BL/6J mice (n = 6) were immunized with Cop-1 emulsified in CFA. Ten days later the mice were subjected to unilateral intraocular injection of toxic amounts of glutamate (200 nmol). As controls, we used a group of mice injected with glutamate only (n = 7) and a group of mice (n = 8) that were immunized with PBS in CFA 10 days before being exposed to glutamate. Three days after their exposure to glutamate, the RGCs were retrogradely labeled. Retinas were excised 1 week after their exposure to glutamate. RGC survival was assessed by counting the labeled cells, and is expressed as mean ± SEM per mm². A two-tailed Student's t test was used for statistical analysis. (B) C57BL/6J mice were immunized with Cop-1 in CFA at the indicated time points before receiving unilateral intraocular injections of toxic amounts of glutamate (200 nmol). After an additonal 7 days they were killed, their retinas were excised, and RGC survival was assessed. Mice that received only glutamate were used as controls. Protection is expressed in terms of RGC survival, calculated as a percentage of RGC survival in control mice.

Figure 3

Life expectancy in ALS mice immunized with Cop-1. (A) Nonvaccinated controls (n = 15) became paralyzed in one or more limbs and died by the age of 211 ± 7 days (mean ± SEM). Cop-1-treated mice survived for 263 ± 8 days. Survival data (expressed by mortality as a function of age in days) were analyzed by the Mantel–Cox test or Cox's proportional hazards regression analysis. Statistical significance was tested by one-way ANOVA, followed by a post hoc Student–Neuman–Keuls procedure with the SPSS-PC software program (SPSS, Chicago). (B) Average rotary activity measured at the indicated time points in Cop-1-treated and untreated mice. Data are expressed as the mean ± SEM. Rotarod testing and weight were compared by ANOVA. Statistical significance was tested by one-way ANOVA followed by a post hoc Student–Neuman–Keuls procedure with the SPSS-PC software program. Differences between treated and untreated mice were observed between days 12 and 20 (P < 0.06), between weeks 21 and 24 (P < 0.008), and between weeks 25 and 28 (P < 0.002).