Effect of Cladribine on Neuronal Apoptosis: New Insight of In Vitro Study in Multiple Sclerosis Therapy

Cladribine induces apoptosis, neuroinflammation, mitochondrial oxidative stress, tau phosphorylation and Aβ (1-42) pathway in the hippocampus: An in vivo approach

Cladribine is a purine nucleoside found to enhance toxic amyloid protein and cause memory impairment. Patients following chemotherapy treatment commonly suffer from cognitive deficits more prevalent in the elderly than adults. A previous research study revealed that cladribine has a high affinity to the brain, increases the level of amyloid precursor protein, and results in learning deficits. The study was designed to validate an animal model of cladribine administration to rats through mitochondrial oxidative stress, inflammation, apoptosis, tau phosphorylation, and amyloid-β (1-42) accumulation. In this study, all rats were orally given cladribine (0.5 and 1 mg/kg) for 28 days, resulting in impaired spatial memory confirmed by behavioural activity. On day 29, all rats were euthanized, and the hippocampal tissues were isolated and used for the estimation of neuroinflammatory markers, biochemicals parameters (glutathione, catalase, lipid peroxidation, and nitrite), amyloid-β (1-42) level, neurotransmitters, and nuclear factor kappa B analysis. Cladribine administration significantly elevated cytokines release, dysbalanced neurotransmitter concentration, and promoted the Aβ accumulation and hyperphosphorylation of tau protein. Our study outcome confirmed that cladribine produces cognitive impairment via activation of Nuclear factor kappa B, mitochondrial oxidative stress and dysbalanced of the endogenous antioxidant defence system.

Design, synthesis and bioevaluation of 1,2,4-thiadiazolidine-3,5-dione derivatives as potential GSK-3β inhibitors for the treatment of Alzheimer's disease

Tideglusib is a non-competitive GSK-3β inhibitor which contain 1,2,4-thiadiazolidine-3,5-dione moiety, and now mainly used for progressive supranuclear palsy due to the lack of some primary cognitive endpoints and secondary endpoints in a phase IIb trail for Alzheimer's disease. Additionally, insufficient evidence exists to support that there are obvious covalent bonds between Tideglusib and GSK-3β. Targeted covalent inhibition strategy could improve the binding efficiency, selectivity and duration of kinase inhibitors. Based on the above premise, two series of targeted compounds with acryloyl warheads were designed and synthesized. The kinase inhibitory activity of the selected compound 10a with better neuroprotective effect improved 2.7 fold than that of Tideglusib. After the preliminary screening of GSK-3β inhibition and neuroprotective activity, the mechanism action of the selected compound 10a was investigated in vitro and in vivo. The results confirmed that 10a with excellent selectivity among the whole tested kinases could significantly reduce the expressions of APP and p-Tau via increasing the level of p-GSK-3β. The pharmacodynamic assay in vivo showed that 10a could markedly improve the learning and memory functions in AD mice induced by AlCl₃ combined with d-galactose. At the same time, the damage of hippocampal neurons in AD mice was obviously reduced. Accordingly, the introduction of acryloyl warheads could increase the GSK-3β inhibitory activity of 1,2,4-thiadiazolidine-3,5-dione derivatives, and the selected compound 10a deserves further research as an effective GSK-3β inhibitor for the potential treatment of AD.

Real-Life Experience of the Effects of Cladribine Tablets on Lymphocyte Subsets and Serum Neurofilament Light Chain Levels in Relapsing Multiple Sclerosis Patients

Although cladribine induces sustained reductions in peripheral T and B lymphocytes, little is known about its effect on axonal damage reduction in multiple sclerosis (MS), which could be demonstrated by assessing the serum neurofilament light chain (sNfL) levels. We investigated the reduction/reconstitution of different lymphocyte subsets (LS) by verifying the correlation with no evidence of disease activity (NEDA) and the variation in sNfL levels during cladribine treatment. We analysed 33 highly active relapsing MS patients and followed them up for 12 ± 3.3 months; blood samples were collected at treatment start (W0) and after 8, 24 and 48 weeks. Seventeen patients (60.7%) showed NEDA during the first treatment. At week 8, we observed a significant decrease in B memory cells, B regulatory 1 CD19+/CD38+ and B regulatory 2 CD19+/CD25+, a significant increase in T regulatory CD4+/CD25+, a slight increase in T cytotoxic CD3+/CD8+ and a non-significant decrease in T helper CD3+/CD4+. Starting from week 24, the B subsets recovered; however, at week 48, CD19+/CD38+ and CD19+/CD25+ reached values near the baseline, while the Bmem were significantly lower. The T cell subsets remained unchanged except for CD4+/CD25+, which increased compared to W0. The LS changes were not predictive of NEDA achievement. The sNfL levels were significantly lower at week 24 (p = 0.046) vs. baseline. These results could demonstrate how cladribine, by inflammatory activity depletion, can also reduce axonal damage, according to the sNfL levels.

Cladribine treatment improves cortical network functionality in a mouse model of autoimmune encephalomyelitis

Background

Cladribine is a synthetic purine analogue that interferes with DNA synthesis and repair next to disrupting cellular proliferation in actively dividing lymphocytes. The compound is approved for the treatment of multiple sclerosis (MS). Cladribine can cross the blood–brain barrier, suggesting a potential effect on central nervous system (CNS) resident cells. Here, we explored compartment-specific immunosuppressive as well as potential direct neuroprotective effects of oral cladribine treatment in experimental autoimmune encephalomyelitis (EAE) mice.

Methods

In the current study, we compare immune cell frequencies and phenotypes in the periphery and CNS of EAE mice with distinct grey and white matter lesions (combined active and focal EAE) either orally treated with cladribine or vehicle, using flow cytometry. To evaluate potential direct neuroprotective effects, we assessed the integrity of the primary auditory cortex neuronal network by studying neuronal activity and spontaneous synaptic activity with electrophysiological techniques ex vivo.

Results

Oral cladribine treatment significantly attenuated clinical deficits in EAE mice. Ex vivo flow cytometry showed that cladribine administration led to peripheral immune cell depletion in a compartment-specific manner and reduced immune cell infiltration into the CNS. Histological evaluations revealed no significant differences for inflammatory lesion load following cladribine treatment compared to vehicle control. Single cell electrophysiology in acute brain slices was performed and showed an impact of cladribine treatment on intrinsic cellular firing patterns and spontaneous synaptic transmission in neurons of the primary auditory cortex. Here, cladribine administration in vivo partially restored cortical neuronal network function, reducing action potential firing. Both, the effect on immune cells and neuronal activity were transient.

Conclusions

Our results indicate that cladribine exerts a neuroprotective effect after crossing the blood–brain barrier independently of its peripheral immunosuppressant action.

Cladribine Tablets for Relapsing-Remitting Multiple Sclerosis: A Clinician's Review

Multiple sclerosis (MS) is a chronic neurodegenerative disease characterized by inflammation and demyelination for which there is currently no cure; therefore, the aim of therapy is to reduce the risk of relapse and disability progression. The treatment options for MS have increased greatly in recent years with the development of several disease-modifying therapies (DMTs) and the advent of immune reconstitution therapy (IRT). IRTs are administered in short-dosing periods to produce long-term effects on the immune system. Treatment with an IRT is based on the 3Rs: reduction, repopulation, and reconstitution of lymphocytes, which leads to restoration of immune effector functions. Cladribine tablets represent a selective, high-efficacy, oral form of IRT for patients with MS that targets lymphocytes and spares innate immune cells. Patients require only two weekly treatment courses, with each course comprising two treatment weeks, in Years 1 and 2; therefore, cladribine tablets are associated with a lower monitoring burden than many other DMTs, while short dosing periods can help to improve adherence. This review provides an overview of IRT and offers the clinician's perspective on the current MS treatment landscape, with a focus on practical advice for the management of patients undergoing treatment with cladribine tablets based on the most recent evidence available, including risks associated with COVID-19 and recommendations for vaccination in patients with MS.