Neuroprotection without Immunomodulation Is Not Sufficient to Reduce First Relapse Severity in Experimental Autoimmune Encephalomyelitis

Abstract

Objectives: Multiple sclerosis can be characterized by a strong neuroinflammatory and progressive neurodegenerative component leading to prolonged disability. The synthetic compound R(+)WIN55,212-2 is reported to be neuroprotective at moderate doses and both neuroprotective and immunomodulatory at high doses, most likely due to differences in receptor affinities. In order to investigate the effects of neuroprotection and immunomodulation in an animal model of multiple sclerosis, we examined the impact of increasing concentrations of R(+)WIN55,212-2 on the inflammatory profile in CNS during first relapse and related this to demyelination, axonal degeneration and relapse severity. Methods: Experimental autoimmune encephalomyelitis was induced in Dark Agouti rats and treatment with R(+)WIN55,212-2 was initiated at symptom debut. The animals were scored clinically throughout the experiment, and axonal degeneration, demyelination, T cells, microglia/macrophages, TNF-α, IL-12, IFN-γ, IL-10 and the T_H17 response were estimated at the peak of the first relapse. Results: Treatment with high-dose R(+)WIN55,212-2 (10 and 20 mg/kg) significantly improved the clinical performance of the animals during relapse. Interestingly, treatment at any dosage did not affect the brain levels of TNF-α, IL-12 and IFN-γ (T_H1 response), whereas high-dose cannabinoid treatment reduced the number of T cells and microglia/macrophages in addition to the T_H17 response. At the same time, we observed a significant reduction in axonal degeneration in all treatment groups whereas only high-dose treatment resulted in reduced demyelination. Conclusion: High-dose R(+)WIN55,212-2 treatment reduces demyelination and axonal degeneration and has immunomodulatory effects which significantly improve clinical performance, whereas a reduction in axonal degeneration on its own, induced by 5 mg/kg R(+)WIN55,212-2, has no impact on first relapse severity.

Cannabinoid Treatment Renders Neurons Less Vulnerable Than Oligodendrocytes in Experimental Autoimmune Encephalomyelitis

“…Our previous experiments demonstrated that immunosuppressive cannabinoid doses reduced demyelination and axonal degeneration as well as improved clinical performance (Hasseldam & Johansen, 2010). Here, we further investigate the mechanisms involved in neuroprotection following low dose cannabinoid treatment in EAE.…”

“…EAE was induced by immunization with 20 µg of the extracellular domain of rat Myelin Oligodendrocyte Glycoprotein (amino acids 1-125, MOG 1-125 ), as described previously (Hasseldam & Johansen, 2010). …”

“…The spinal cord was removed and immersed in fixative (4% phosphate-buffered formaldehyde) for paraffin embedding and the brain was snap-frozen and kept at -80 • C until homogenization, as described previously (Hasseldam & Johansen, 2010). For qRT-PCR one randomly chosen hemisphere underwent RNA purification using Trizol (Invitrogen, Carlsbad, California) according to the manufacturer's instructions.…”

“…Cannabinoid treatment have shown both neuroprotective and immunomodulatory effects at high doses in animal models including Experimental Autoimmune Encephalomyelitis (EAE)-a model that shares essential pathological features with MS (Croxford et al, 2008;Hasseldam & Johansen, 2010). Our previous experiments demonstrated that immunosuppressive cannabinoid doses reduced demyelination and axonal degeneration as well as improved clinical performance (Hasseldam & Johansen, 2010).…”

Neuroprotection in Experimental Autoimmune Encephalomyelitis and Progressive Multiple Sclerosis by Cannabis-Based Cannabinoids

“…These probably cause significant stress-responses that are known to be immunosuppressive in EAE (Bolton et al 1997). Importantly, there is no solid data to suggest that doses of medical cannabis cause significant immunosuppressive effects in MS, following analysis of peripheral immune responses (Killestein et al 2003;Katona et al 2005;Sexton et al 2014 (Pryce et al2003;Croxford et al 2008;Webb et al 2008;Hasseldam and Johansen 2010;Hernández-Torres et al 2014;BernalChico et al 2015). In EAE, this is seen by a better functional recovery and a reduced accumulation of disability following paralytic attack Baker et al 2011;Al-Izki et al 2014).…”