Transgenic and physiological mouse models give insights into different aspects of amyotrophic lateral sclerosis

Ropinirole hydrochloride remedy for amyotrophic lateral sclerosis - Protocol for a randomized, double-blind, placebo-controlled, single-center, and open-label continuation phase I/IIa clinical trial (ROPALS trial)

Introduction

Amyotrophic lateral sclerosis (ALS) is an intractable and incurable neurological disease. It is a progressive disease characterized by muscle atrophy and weakness caused by selective vulnerability of upper and lower motor neurons. In disease research, it has been common to use mouse models carrying mutations in responsible genes for familial ALS as pathological models of ALS. However, there is no model that has reproduced the actual conditions of human spinal cord pathology. Thus, we developed a method of producing human spinal motor neurons using human induced pluripotent stem cells (iPSCs) and an innovative experimental technique for drug screening. As a result, ropinirole hydrochloride was eventually discovered after considering such results as its preferable transitivity in the brain and tolerability, including possible adverse reactions. Therefore, we explore the safety, tolerability and efficacy of ropinirole hydrochloride as an ALS treatment in this clinical trial.

Methods

The ROPALS trial is a single-center double-blind randomized parallel group-controlled trial of the safety, tolerability, and efficacy of the ropinirole hydrochloride extended-release tablet (Requip CR) at 2- to 16-mg doses in patients with ALS. Twenty patients will be recruited for the active drug group (fifteen patients) and placebo group (five patients). All patients will be able to receive the standard ALS treatment of riluzole if not changed the dosage during this trial. The primary outcome will be safety and tolerability at 24 weeks, defined from the date of randomization. Secondary outcome will be the efficacy, including any change in the ALS Functional Rating Scale-Revised (ALSFRS-R), change in the Combined Assessment of Function and Survival (CAFS), and the composite endpoint as a sum of Z-transformed scores on various clinical items. Notably, we will perform an explorative search for a drug effect evaluation using the patient-derived iPSCs to prove this trial concept. Eligible patients will have El Escorial Possible, clinically possible and laboratory-supported, clinically probable, or clinically definite amyotrophic lateral sclerosis with disease duration less than 60 months (inclusive), an ALSFRS-R score ≥2 points on all items and age from 20 to 80 years.

Conclusion

Patient recruitment began in December 2018 and the last patient is expected to complete the trial protocol in November 2020.

Trial registration

Current controlled trials UMIN000034954 and JMA-IIA00397.

Protocol version

version 1.6 (Date; 5/Apr/2019).

The Biosynthesis, Signaling, and Neurological Functions of Bile Acids

Bile acids (BA) are amphipathic steroid acids synthesized from cholesterol in the liver. They act as detergents to expedite the digestion and absorption of dietary lipids and lipophilic vitamins. BA are also considered to be signaling molecules, being ligands of nuclear and cell-surface receptors, including farnesoid X receptor and Takeda G-protein receptor 5. Moreover, BA also activate ion channels, including the bile acid-sensitive ion channel and epithelial Na⁺ channel. BA regulate glucose and lipid metabolism by activating these receptors in peripheral tissues, such as the liver and brown and white adipose tissue. Recently, 20 different BA have been identified in the central nervous system. Furthermore, BA affect the function of neurotransmitter receptors, such as the muscarinic acetylcholine receptor and γ-aminobutyric acid receptor. BA are also known to be protective against neurodegeneration. Here, we review recent findings regarding the biosynthesis, signaling, and neurological functions of BA.

Cytoplasmic functions of TDP-43 and FUS and their role in ALS

TAR DNA-binding protein of 43 kDa (TDP-43) and fused in sarcoma (FUS) are RNA binding proteins (RBPs) primarily located in the nucleus, and involved in numerous aspects of RNA metabolism. Both proteins can be found to be depleted from the nucleus and accumulated in cytoplasmic inclusions in two major neurodegenerative conditions, amyotrophic lateral sclerosis and frontotemporal dementia. Recent evidences suggest that, in addition to their nuclear functions, both TDP-43 and FUS are involved in multiple processes in the cytoplasm, including mRNA stability and transport, translation, the stress response, mitochondrial function and autophagy regulation. Here, we review the most recent advances in understanding their functions in the cytoplasm and how these are affected in disease.

Experimental Motor Neuron Disease Induced in Mice with Long-Term Repeated Intraperitoneal Injections of Serum from ALS Patients

In an earlier study, signs of commencing degeneration of spinal motor neurons were induced in mice with short-term intraperitoneal injections of immunoglobulin G (IgG) taken from patients with amyotrophic lateral sclerosis (ALS). Since in that study, neither weakness nor loss of motor neurons was noted, to test whether the ALS IgG in this paradigm has the potential to evoke relentless degeneration of motor neurons, treatment with repeated injections over a longer period was carried out. Mice were systematically injected intraperitoneally with serum taken from ALS patients over a 75-day period. At selected time points, the isometric force of the limbs, number of spinal motor neurons and their intracellular calcium levels were determined. Furthermore, markers of glial activation and the motoneuronal uptake of human IgG were monitored. During this period, gliosis and progressive motoneuronal degeneration developed, which led to gradual loss of spinal motor neurons, more than 40% at day 21, along with decreasing muscle strength in the limbs. The inclusion-like accumulation of IgG appeared in the perikarya with the increase of intracellular calcium in the cell bodies and motor nerve terminals. Our results demonstrate that ALS serum can transfer motor neuron disease to mice.

Impact of traumatic brain injury on amyotrophic lateral sclerosis: from bedside to bench

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the loss of upper and lower motor neurons, which manifests clinically as progressive weakness. Although several epidemiological studies have found an association between traumatic brain injury (TBI) and ALS, there is not a consensus on whether TBI is an ALS risk factor. It may be that it can cause ALS in a subset of susceptible patients, based on a history of repetitive mild TBI and genetic predisposition. This cannot be determined based on clinical observational studies alone. Better preclinical models are necessary to evaluate the effects of TBI on ALS onset and progression. To date, only a small number of preclinical studies have been performed, mainly in the superoxide dismutase 1 transgenic rodents, which, taken together, have mixed results and notable methodological limitations. The more recent incorporation of additional animal models such as Drosophila flies, as well as patient-induced pluripotent stem cell-derived neurons, should facilitate a better understanding of a potential functional interaction between TBI and ALS.