Cerebrospinal Fluid from Sporadic Amyotrophic Lateral Sclerosis Patients Induces Mitochondrial and Lysosomal Dysfunction

Abstract

In our laboratory, we have developed (1) an in vitro model of sporadic Amyotrophic Lateral Sclerosis (sALS) involving exposure of motor neurons to cerebrospinal fluid (CSF) from sALS patients and (2) an in vivo model involving intrathecal injection of sALS-CSF into rat pups. In the current study, we observed that spinal cord extract from the in vivo sALS model displayed elevated reactive oxygen species (ROS) and mitochondrial dysfunction. Quantitative proteomic analysis of sub-cellular fractions from spinal cord of the in vivo sALS model revealed down-regulation of 35 mitochondrial proteins and 4 lysosomal proteins. Many of the down-regulated mitochondrial proteins contribute to alterations in respiratory chain complexes and organellar morphology. Down-regulated lysosomal proteins Hexosaminidase, Sialidase and Aryl sulfatase also displayed lowered enzyme activity, thus validating the mass spectrometry data. Proteomic analysis and validation by western blot indicated that sALS-CSF induced the over-expression of the pro-apoptotic mitochondrial protein BNIP3L. In the in vitro model, sALS-CSF induced neurotoxicity and elevated ROS, while it lowered the mitochondrial membrane potential in rat spinal cord mitochondria in the in vivo model. Ultra structural alterations were evident in mitochondria of cultured motor neurons exposed to ALS-CSF. These observations indicate the first line evidence that sALS-CSF mediated mitochondrial and lysosomal defects collectively contribute to the pathogenesis underlying sALS.

Linking mitochondrial dysfunction, metabolic syndrome and stress signaling in Neurodegeneration

“…Overexpression of FUS protein provokes death in primary cortical neurons and motor neuronal NSC34 cells via the mitochondrial apoptotic pathway which is independent of transactive response DNA-binding protein-43 [76]. Recently, sALS-CSF induced overexpression of the pro-apoptotic mitochondrial protein BNIP3L has also been reported to be associated with induced neurotoxicity, elevated ROS and lowered mitochondrial membrane potential, which collectively contribute to the pathogenesis of ALS [77].…”

Human Spinal Motor Neurons Are Particularly Vulnerable to Cerebrospinal Fluid of Amyotrophic Lateral Sclerosis Patients

“…These models mainly include primary murine cortical or spinal MN cultures and spinal cord neuroblastoma hybrid cell line NSC34 cultures. A multitude of phenotypes could be observed by this including aggregation of transactive response DNA binding protein 43 kDA (TDP-43) in the case of ALS-frontotemporal dementia (FTLD)-CSF [8], neurofilament abnormalities [9], gliosis [10], endoplasmic reticulum (ER)-stress [6], mitochondrial dysfunction [11] and Golgi fragmentation [6,12]. In addition, intrathecal infusion of ALS-CSF in an in vivo rat model mimicked neuropathological changes similar to the ones found in postmortem tissue of ALS patients [4].…”

Immunoglobulins G from Sera of Amyotrophic Lateral Sclerosis Patients Induce Oxidative Stress and Upregulation of Antioxidative System in BV-2 Microglial Cell Line

“…On the other hand, treatment with sALS CSF caused disbalance in astrocytic cytokines, elevating production and release of proinflammatory, and decreasing anti-inflammatory cytokines and beneficial trophic factors, with impaired regulation of ROS, nitric oxide (NO), and glutamate ( 22 ). Elevated ROS and cellular peroxide levels, as well as increased mitochondrial SOD (MnSOD) activity were found in spinal cord extracts of pups intrathecally injected with sALS CSF ( 23 ), stressing out the role of oxidative stress. However, mice intraperitoneally injected with sALS IgG showed increased levels of both pro- and anti-inflammatory cytokines in the spinal cord, causing initial morphological and electrophysiological manifestations of degeneration, but with no actual death of spinal motor neurons ( 24 ).…”