Matrine treatment reduces retinal ganglion cell apoptosis in experimental optic neuritis.

Inflammatory demyelination and axonal injury of the optic nerve are hallmarks of optic neuritis (ON), which often occurs in multiple sclerosis and is a major cause of visual disturbance in young adults. Although a high dose of corticosteroids can promote visual recovery, it cannot prevent permanent neuronal damage. Novel and effective therapies are thus required. Given the recently defined capacity of matrine (MAT), a quinolizidine alkaloid derived from the herb Radix Sophorae flavescens, in immunomodulation and neuroprotection, we tested in this study the effect of matrine on rats with experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. MAT administration, started at disease onset, significantly suppressed optic nerve infiltration and demyelination, with reduced numbers of Iba1+ macrophages/microglia and CD4+ T cells, compared to those from vehicle-treated rats. Increased expression of neurofilaments, an axon marker, reduced numbers of apoptosis in retinal ganglion cells (RGCs). Moreover, MAT treatment promoted Akt phosphorylation and shifted the Bcl-2/Bax ratio back towards an antiapoptotic one, which could be a mechanism for its therapeutic effect in the ON model. Taken as a whole, our results demonstrate that MAT attenuated inflammation, demyelination and axonal loss in the optic nerve, and protected RGCs from inflammation-induced cell death. MAT may therefore have potential as a novel treatment for this disease that may result in blindness.

Valproic acid attenuates inflammation of optic nerve and apoptosis of retinal ganglion cells in a rat model of optic neuritis.

AIMS: Optic neuritis (ON) is an inflammatory disease of the optic nerve, which often occurs in patients with multiple sclerosis (MS) and leads to retinal ganglion cell (RGC) death and even severe visual loss. Valproic acid (VPA) is a short-chain branched fatty acid with anti-epileptic, neuro-protective and anti-inflammatory effects. Here, we examined the effects of VPA in experimental autoimmune encephalomyelitis (EAE) rats and explored the underlying mechanisms. MAIN METHODS: EAE was induced by subcutaneous injection with myelin basic protein, emulsified with complete Freund's adjuvant and Mycobacterium tuberculosis H37Ra into the Lewis rats. Subsequently, animals in the VPA groups were treated orally with VPA (250 or 500 mg/kg) once a day for 13 days. KEY FINDINGS: VPA treatment significantly attenuated inflammation and microgliosis in optic nerve in EAE-ON rats, as evidenced by the decrease in the mRNA levels of interferon (INF)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-17, and inducible nitric oxide synthase (iNOS), the suppression in nuclear factor (NF)-κB signal pathway as well as the down-regulation of CD11b expression in optic nerve. Additionally, the apoptotic RGCs were remarkably increased in the EAE retina, which was inhibited by VPA treatment. Consistent with the TUNEL staining, VPA administration also obviously suppressed the ratio of Bax: Bcl-2 and the expression of cleaved caspase-3 and PARP in optic nerve in EAE rats. SIGNIFICANCE: Our findings demonstrated that VPA treatment could prevent inflammation responses and RGC apoptosis in optic nerve in EAE-ON rats, suggesting that VPA may be available for optic nerve protection during ON.

Calpain inhibition attenuates apoptosis of retinal ganglion cells in acute optic neuritis.

PURPOSE: Optic neuritis (ON), inflammation of the optic nerve, is strongly associated with the pathogenesis of multiple sclerosis (MS) and is initiated by the attack of autoreactive T cells against self-myelin antigens, resulting in demyelination, degeneration of retinal ganglion cells (RGCs), and cumulative visual impairment. METHODS: Experimental autoimmune encephalomyelitis (EAE) was induced in Lewis rats on day 0, and animals received daily intraperitoneal injections of calpain inhibitor (calpeptin) or vehicle from day 1 until killed. Retinal cell death was analyzed by DNA fragmentation, and surviving ganglion cells were quantified after double labeling of retinal tissue with TUNEL and Brn3a. The expression of apoptotic and inflammatory proteins was determined by Western blotting. RESULTS: It was demonstrated that calpain inhibition downregulates expression of proapoptotic proteins and the proinflammatory molecule nuclear factor-kappa B (NF-κB) in the retina of Lewis rats with acute EAE. Immunofluorescent labeling revealed that apoptotic cells in the RGC layer of vehicle-treated EAE animals were Brn3a positive, and a moderate dose of calpeptin dramatically reduced the frequency of apoptotic RGCs. CONCLUSIONS: These results suggest that calpain inhibition might be a useful supplement to immunomodulatory therapies such as corticosteroids in ON, due to its neuroprotective effect on RGCs.

[Optic neuritis and vitamin C].

Twenty five patients with optic neuritis (ON) of unknown etiology were treated with a high dosage of intravenous vitamin C. We measured blood levels of vitamin A, B1, B2, B6, B12, C, E, folate and zinc. All levels were compared with the normal values of our laboratory. The blood level of vitamin C (p < 0.001) was significantly less than the mean value of the normal. The blood levels of vitamin E, B6 (p < 0.01) and zinc (p < 0.001) also significantly decreased. Intravenous administration of vitamin C was given in those patients with decreased blood level of vitamin C. In order to compare the effect on vision by this treatment, the amplitude of recovery of vision, the time needed to attain the maximum vision, and the speed of visual recovery were analyzed. The results were compared with groups receiving other treatments. That is, Group A received intravenous administration of high dosage of vitamin C, Group B, intravenous pulse administration of corticosterone, Group C, oral administration of corticosterone, and Group D, oral administration of vitamin B12. Vision was significantly improved in all groups. There was no significant difference in improvement of visual acuity. Intravenous administration of vitamin C can be evaluated as the method of choice for the treatment of patients with ON. A possible mode of action by vitamin C on free radicals is discussed.

Disruption of the blood-brain barrier in experimental optic neuritis: immunocytochemical co-localization of H2O2 and extravasated serum albumin.

PURPOSE: To probe the role of endogenous hydrogen peroxide (H2O2) in the pathogenesis of disruption of the blood-brain barrier (BBB) associated with experimental allergic encephalomyelitis (EAE), an animal model for primary central nervous system demyelination. METHODS: Strain-13 guinea pigs were sensitized for EAE with central myelin in complete Freund's adjuvant. Magnetic resonance imaging with Gd-DTPA was performed twice a week for 2 weeks to assess disruption of the BBB, in vivo, by the enhancement of the optic nerves. Two weeks after antigenic sensitization, ultracytochemical localization of endogenous H2O2 was performed using the cerium perhydroxide method, with co-localization of endogenous serum albumin extravasation using gold-labeled antibodies against serum albumin. Examination of blood vessels for perivascular immunogold-labeled serum albumin and H2O2 derived reaction product began in the optic nerve head and proceeded toward the retrobulbar optic nerve until a total of 20 vessels were evaluated per animal. RESULTS: Magnetic resonance imaging revealed Gd-DTPA enhancement of the optic nerves in all animals sensitized for EAE. Optic nerve ultrastructure revealed colloidal gold-labeled antibodies against serum albumin in the perivascular and adjacent interstitial spaces of capillaries and small venules in which H2O2 derived cerium perhydroxide reaction product was also simultaneously evident. Immunogold-labeled serum albumin was predominantly confined to the intravascular compartment of the optic nerve in the absence of perivascular H2O2 and/or perivascular foci of inflammatory cells. The difference between the mean percentage of blood vessels (61.8%) with co-localization of perivascular immunogold-labeled serum albumin and cerium perhydroxide reaction product, to the mean percentage of blood vessels (9.5%) with perivascular immunogold-labeled serum albumin in the absence of cerium perhydroxide, was statistically significant (P = 0.0019). CONCLUSIONS: Endogenous H2O2, found at the foci of BBB disruption, may be one of the mediators involved in the alteration of vascular permeability in experimental optic neuritis.