Neuroprotective Effect of Apolipoprotein D in Cuprizone-Induced Cell Line Models: A Potential Therapeutic Approach for Multiple Sclerosis and Demyelinating Diseases

Zebrafish as a Model for Multiple Sclerosis

Background: Zebrafish have become a key model organism in neuroscience research because of their unique advantages. Their genetic, anatomical, and physiological similarities to humans, coupled with their rapid development and transparent embryos, make them an excellent tool for investigating various aspects of neurobiology. They have specifically emerged as a valuable and versatile model organism in biomedical research, including the study of neurological disorders such as multiple sclerosis. Multiple sclerosis is a chronic autoimmune disease known to cause damage to the myelin sheath that protects the nerves in the brain and spinal cord. Objective: This review emphasizes the importance of continued research in both in vitro and in vivo models to advance our understanding of MS and develop effective treatments, ultimately improving the quality of life for those affected by this debilitating disease. Conclusions: Recent studies show the significance of zebrafish as a model organism for investigating demyelination and remyelination processes, providing new insights into MS pathology and potential therapies.

Anti-inflammatory Effects of Umbilical Cord Mesenchymal Stem Cell and Autologous Conditioned Serum on Oligodendrocyte, Astrocyte, and Microglial Specific Gene in Cuprizone Animal Model

BACKGROUND

Inflammation, myelin loss, astrocytosis, and microgliosis are pathological signs of the autoimmune and demyelinating disease known as multiple sclerosis (MS). Axonal and neuronal degenerations have basic molecular pathways. The remyelination process can be influenced by the secretome of mesenchymal stem cells due to their capacity for immunomodulation, differentiation, and neuroprotection. Microglial cells are divided into two subgroups: M1 and M2 phenotypes. A crucial component of the microglial function is the colony stimulating factor 1 receptor (CSF1R). We aimed to evaluate the immunomodulating effects of secretome and conditioned serum on the microglial phenotypes and improvement of demyelination in a cuprizone model of MS.

METHODS

The study used 48 male C57BL/6 mice, which were randomly distributed into 6 subgroups (n = 8), i.e., control, cuprizone, MSC (confluency 40% and 80%) secretome group, and blood derived conditioned serum (autologous and humanized). The animals were fed with 0.2% cuprizone diet for 12 weeks. Supplements were injected into the lateral tail vein using a 27-gauge needle every 3 days 500 μl per injection.

RESULTS

At 14 days after transplantation, animals from each group were sacrificed and analyzed by Real time PCR. The results showed that the administration of MSC secretome can efficiently reduce expression of pro-inflammatory cytokines (IL-1, IL6 and TNF-α) in the corpus callosum; also, conditioned serum downregulated IL-1. Moreover, the oligodendrocyte-specific gene was upregulated by secretome and conditioned serum treatment. Also, the expression of microglial- specific gene was reduced after treatment.

CONCLUSION

These findings demonstrated that the secretome isolated from MSCs used as a therapy decreased and increased the M1 and M2 levels, respectively, to control neuroinflammation in CPZ mice. In conclusion, the current study showed the viability of devising a method to prepare suitable MSCs and secreted factor to cure neurodegenerative diseases, as well as the capability of regulating MSC secretome patterns by manipulating the cell density.

Apolipoprotein D as a Potential Biomarker in Neuropsychiatric Disorders

Neuropsychiatric disorders (NDs) are a diverse group of pathologies, including schizophrenia or bipolar disorders, that directly affect the mental and physical health of those who suffer from them, with an incidence that is increasing worldwide. Most NDs result from a complex interaction of multiple genes and environmental factors such as stress or traumatic events, including the recent Coronavirus Disease (COVID-19) pandemic. In addition to diverse clinical presentations, these diseases are heterogeneous in their pathogenesis, brain regions affected, and clinical symptoms, making diagnosis difficult. Therefore, finding new biomarkers is essential for the detection, prognosis, response prediction, and development of new treatments for NDs. Among the most promising candidates is the apolipoprotein D (Apo D), a component of lipoproteins implicated in lipid metabolism. Evidence suggests an increase in Apo D expression in association with aging and in the presence of neuropathological processes. As a part of the cellular neuroprotective defense machinery against oxidative stress and inflammation, changes in Apo D levels have been demonstrated in neuropsychiatric conditions like schizophrenia (SZ) or bipolar disorders (BPD), not only in some brain areas but in corporal fluids, i.e., blood or serum of patients. What is not clear is whether variation in Apo D quantity could be used as an indicator to detect NDs and their progression. This review aims to provide an updated view of the clinical potential of Apo D as a possible biomarker for NDs.

The Lipocalin Apolipoprotein D Functional Portrait: A Systematic Review

Apolipoprotein D is a chordate gene early originated in the Lipocalin protein family. Among other features, regulation of its expression in a wide variety of disease conditions in humans, as apparently unrelated as neurodegeneration or breast cancer, have called for attention on this gene. Also, its presence in different tissues, from blood to brain, and different subcellular locations, from HDL lipoparticles to the interior of lysosomes or the surface of extracellular vesicles, poses an interesting challenge in deciphering its physiological function: Is ApoD a moonlighting protein, serving different roles in different cellular compartments, tissues, or organisms? Or does it have a unique biochemical mechanism of action that accounts for such apparently diverse roles in different physiological situations? To answer these questions, we have performed a systematic review of all primary publications where ApoD properties have been investigated in chordates. We conclude that ApoD ligand binding in the Lipocalin pocket, combined with an antioxidant activity performed at the rim of the pocket are properties sufficient to explain ApoD association with different lipid-based structures, where its physiological function is better described as lipid-management than by long-range lipid-transport. Controlling the redox state of these lipid structures in particular subcellular locations or extracellular structures, ApoD is able to modulate an enormous array of apparently diverse processes in the organism, both in health and disease. The new picture emerging from these data should help to put the physiological role of ApoD in new contexts and to inspire well-focused future research.

Cuprizone-Induced Neurotoxicity in Human Neural Cell Lines Is Mediated by a Reversible Mitochondrial Dysfunction: Relevance for Demyelination Models

Suitable in vivo and in vitro models are instrumental for the development of new drugs aimed at improving symptoms or progression of multiple sclerosis (MS). The cuprizone (CPZ)-induced murine model has gained momentum in recent decades, aiming to address the demyelination component of the disease. This work aims at assessing the differential cytotoxicity of CPZ in cells of different types and from different species: human oligodendroglial (HOG), human neuroblastoma (SH-SY5Y), human glioblastoma (T-98), and mouse microglial (N-9) cell lines. Moreover, the effect of CPZ was investigated in primary rat brain cells. Cell viability was assayed by oxygen rate consumption and by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-based (MTT) method. Our results demonstrated that CPZ did not cause death in any of the assayed cell models but affected mitochondrial function and aerobic cell respiration, thus compromising cell metabolism in neural cells and neuron-glia co-cultures. In this sense, we found differential vulnerability between glial cells and neurons as is the case of the CPZ-induced mouse model of MS. In addition, our findings demonstrated that reduced viability was spontaneous reverted in a time-dependent manner by treatment discontinuation. This reversible cell-based model may help to further investigate the role of mitochondria in the disease, and study the molecular intricacies underlying the pathophysiology of the MS and other demyelinating diseases.