No abstract

Multiple neurodegenerative diseases (NDDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD) are being suggested to have common cellular and molecular pathological mechanisms, characterized mainly by protein misfolding and aggregation. These large inclusions, most likely, represent an end stage of a molecular cascade; however, the soluble misfolded proteins, which take part in earlier steps of this cascade, are the more toxic players. These pathological proteins, which characterize each specific disease, lead to the selective vulnerability of different neurons, likely resulting from a combination of different intracellular mechanisms, including mitochondrial dysfunction, ER stress, proteasome inhibition, excitotoxicity, oxidative damage, defects in nucleocytoplasmic transport, defective axonal transport and neuroinflammation. Damage within these neurons is enhanced by damage from the nonneuronal cells, via inflammatory processes that accelerate the progression of these diseases. In this review, while acknowledging the hallmark proteins which characterize the most common NDDs; we place specific focus on the common overlapping mechanisms leading to disease pathology despite these different molecular players and discuss how this convergence may occur, with the ultimate hope that therapies effective in one disease may successfully translate to another.

Background Amyotrophic lateral sclerosis (ALS) is a fatal multifactorial neurodegenerative disease characterized by the selective death of motor neurons. Cytosolic phospholipase A2 alpha (cPLA2α) upregulation and activation in the spinal cord of ALS patients has been reported. We have previously shown that cPLA2α upregulation in the spinal cord of mutant SOD1 transgenic mice (SOD1G93A) was detected long before the development of the disease, and inhibition of cPLA2α upregulation delayed the disease’s onset. The aim of the present study was to determine the mechanism for cPLA2α upregulation. Methods Immunofluorescence analysis and western blot analysis of misfolded SOD1, cPLA2α and inflammatory markers were performed in the spinal cord sections of SOD1G93A transgenic mice and in primary motor neurons. Over expression of mutant SOD1 was performed by induction or transfection in primary motor neurons and in differentiated NSC34 motor neuron like cells. Results Misfolded SOD1 was detected in the spinal cord of 3 weeks old mutant SOD1G93A mice before cPLA2α upregulation. Elevated expression of both misfolded SOD1 and cPLA2α was specifically detected in the motor neurons at 6 weeks with a high correlation between them. Elevated TNFα levels were detected in the spinal cord lysates of 6 weeks old mutant SOD1G93A mice. Elevated TNFα was specifically detected in the motor neurons and its expression was highly correlated with cPLA2α expression at 6 weeks. Induction of mutant SOD1 in primary motor neurons induced cPLA2α and TNFα upregulation. Over expression of mutant SOD1 in NSC34 cells caused cPLA2α upregulation which was prevented by antibodies against TNFα. The addition of TNFα to NSC34 cells caused cPLA2α upregulation in a dose dependent manner. Conclusions Motor neurons expressing elevated cPLA2α and TNFα are in an inflammatory state as early as at 6 weeks old mutant SOD1G93A mice long before the development of the disease. Accumulated misfolded SOD1 in the motor neurons induced cPLA2α upregulation via induction of TNFα.

Multiple sclerosis (MS) is a widespread chronic neuroinflammatory and neurodegenerative disease. Microglia play a crucial role in the pathogenesis of MS via the release of cytokines and reactive oxygen species, e.g., nitric oxide. Research involving the role of phytocannabinoids in neuroinflammation is currently receiving much attention. Cannabigerol is a main phytocannabinoid, which has attracted significant pharmacological interest due to its non-psychotropic nature. In this research, we studied the effects of cannabigerol on microglial inflammation in vitro, followed by an in vivo study. Cannabigerol attenuated the microglial production of nitric oxide in BV2 microglia and primary glial cells; concomitant treatment of the cells with cannabigerol and telmisartan (a neuroprotective angiotensin receptor blocker) decreased nitric oxide production additively. Inducible nitric oxide synthase (iNOS) expression was also reduced by cannabigerol. Moreover, tumor necrosis factor-α (TNF-α), a major cytokine involved in MS, was significantly reduced by cannabigerol in both cell cultures. Next, we studied the effects of cannabigerol in vivo using a mice model of MS, experimental autoimmune encephalomyelitis (EAE). The clinical scores of EAE mice were attenuated upon cannabigerol treatment; additionally, lumbar sections of EAE mice showed enhanced neuronal loss (relative to control mice), which was restored by cannabigerol treatment. Altogether, the set of experiments presented in this work indicates that cannabigerol possesses an appealing therapeutic potential for the treatment of MS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the degeneration of motor neurons. Mutations in the superoxide dismutase (SOD1) gene, causing protein misfolding and aggregation, were suggested as the pathogenic mechanisms involved in familial ALS cases. In the present study, we investigated the potential therapeutic effect of C4 and C5, two derivatives of the chemical chaperone 4-phenylbutyric acid (4-PBA). By combining in vivo and in vitro techniques, we show that, although C4 and C5 successfully inhibited amyloid aggregation of recombinant mutant SOD1 in a dose-dependent manner, they failed to suppress the accumulation of misfolded SOD1. Moreover, C4 or C5 daily injections to SOD1G93A mice following onset had no effect on either the accumulation of misfolded SOD1 or the neuroinflammatory response in the spinal cord and, consequently, failed to extend the survival of SOD1G93A mice or to improve their motor symptoms. Finally, pharmacokinetic (PK) studies demonstrated that high concentrations of C4 and C5 reached the brain and spinal cord but only for a short period of time. Thus, our findings suggest that use of such chemical chaperones for ALS drug development may need to be optimized for more effective results.