The updated development of blood-based biomarkers for Huntington's disease

Growth Factors and Their Application in the Therapy of Hereditary Neurodegenerative Diseases

Hereditary neurodegenerative diseases (hNDDs) such as Alzheimer's, Parkinson's, Huntington's disease, and others are primarily characterized by their progressive nature, severely compromising both the cognitive and motor abilities of patients. The underlying genetic component in hNDDs contributes to disease risk, creating a complex genetic landscape. Considering the fact that growth factors play crucial roles in regulating cellular processes, such as proliferation, differentiation, and survival, they could have therapeutic potential for hNDDs, provided appropriate dosing and safe delivery approaches are ensured. This article presents a detailed overview of growth factors, and explores their therapeutic potential in treating hNDDs, emphasizing their roles in neuronal survival, growth, and synaptic plasticity. However, challenges such as proper dosing, delivery methods, and patient variability can hinder their clinical application.

Advances in Clinical Therapies for Huntington's Disease and the Promise of Multi-Targeted/Functional Drugs Based on Clinicaltrials.gov

Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder characterized by a triad of motor, cognitive, and psychiatric problems. Caused by CAG repeat expansion in the huntingtin gene (HTT), the disease involves a complex network of pathogenic mechanisms, including synaptic dysfunction, impaired autophagy, neuroinflammation, oxidative damage, mitochondrial dysfunction, and extrasynaptic excitotoxicity. Although current therapies targeting the pathogenesis of HD primarily aim to reduce mHTT levels by targeting HTT DNA, RNA, or proteins, these treatments only ameliorate downstream pathogenic effects. While gene therapies, such as antisense oligonucleotides, small interfering RNAs and gene editing, have emerged in the field of HD treatment, their safety and efficacy are still under debate. Therefore, pharmacological therapy remains the most promising breakthrough, especially multi-target/functional drugs, which have diverse pharmacological effects. This review summarizes the latest progress in HD drug development based on clinicaltrials.gov search results (Search strategy: key word "Huntington's disease" in HD clinical investigational drugs registered as of December 31, 2023), and highlights the key role of multi-target/functional drugs in HD treatment strategies.

High Levels of Mutant Huntingtin Protein in Tear Fluid From Huntington's Disease Gene Expansion Carriers

OBJECTIVE

Huntington's disease (HD) is an autosomal dominant, fully penetrant, neurodegenerative disease that most commonly affects middle-aged adults. HD is caused by a CAG repeat expansion in the HTT gene, resulting in the expression of mutant huntingtin (mHTT). Our aim was to detect and quantify mHTT in tear fluid, which, to our knowledge, has never been measured before.

METHODS

We recruited 20 manifest and 13 premanifest HD gene expansion carriers, and 20 age-matched controls. All patients underwent detailed assessments, including the Unified Huntington's Disease Rating Scale (UHDRS) total motor score (TMS) and total functional capacity (TFC) score. Tear fluid was collected using paper Schirmer's strips. The level of tear mHTT was determined using single-molecule counting SMCxPRO technology.

RESULTS

The average tear mHTT levels in manifest (67,223 ± 80,360 fM) and premanifest patients (55,561 ± 45,931 fM) were significantly higher than those in controls (1,622 ± 2,179 fM). We noted significant correlations between tear mHTT levels and CAG repeat length, "estimated years to diagnosis," disease burden score and UHDRS TMS and TFC. The receiver operating curve demonstrated an almost perfect score (area under the curve [AUC] = 0.9975) when comparing controls to manifest patients. Similarly, the AUC between controls and premanifest patients was 0.9846. The optimal cutoff value for distinguishing between controls and manifest patients was 4,544 fM, whereas it was 6,596 fM for distinguishing between controls and premanifest patients.

CONCLUSION

Tear mHTT has potential for early and noninvasive detection of alterations in HD patients and could be integrated into both clinical trials and clinical diagnostics.

The characteristic and prognostic role of blood inflammatory markers in patients with Huntington's disease from China

Objectives

This study aims to elucidate the role of peripheral inflammation in Huntington's disease (HD) by examining the correlation of peripheral inflammatory markers with clinical manifestations and disease prognosis.

Methods

This investigation involved 92 HD patients and 92 matched healthy controls (HCs). We quantified various peripheral inflammatory markers and calculated their derived metrics including neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio (LMR), and systemic immune-inflammation index (SII). Clinical assessments spanning cognitive, motor, and disease severity were administered. Comparative analysis of inflammatory markers and clinical correlations between HD and controls was performed. Kaplan-Meier survival analysis and Cox regression model were used to assess the effect of inflammatory markers on survival.

Results

The study revealed that HD patients had significantly reduced lymphocyte counts, and LMR. Conversely, NLR, PLR, and SII were elevated compared to HCs. Lymphocyte levels inversely correlated with the age of onset and monocyte levels inversely correlated with the UHDRS-total functional capacity (TFC) scores. After adjusting for age, sex, and CAG repeat length, lymphocyte count, NLR, PLR, and SII were significantly correlated with the progression rate of TFC scores. Elevated levels of white blood cells and monocytes were associated with an increased risk of disability and mortality in the HD cohort.

Conclusion

Our findings indicate that HD patients display a distinct peripheral inflammatory profile with increased NLR, PLR, and SII levels compared to HCs. The peripheral inflammation appears to be linked with accelerated disease progression and decreased survival in HD.

Perinatal Tissue-Derived Stem Cells: An Emerging Therapeutic Strategy for Challenging Neurodegenerative Diseases

Over the past 20 years, stem cell therapy has been considered a promising option for treating numerous disorders, in particular, neurodegenerative disorders. Stem cells exert neuroprotective and neurodegenerative benefits through different mechanisms, such as the secretion of neurotrophic factors, cell replacement, the activation of endogenous stem cells, and decreased neuroinflammation. Several sources of stem cells have been proposed for transplantation and the restoration of damaged tissue. Over recent decades, intensive research has focused on gestational stem cells considered a novel resource for cell transplantation therapy. The present review provides an update on the recent preclinical/clinical applications of gestational stem cells for the treatment of protein-misfolding diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). However, further studies should be encouraged to translate this promising therapeutic approach into the clinical setting.

Metabolomics: An Emerging "Omics" Platform for Systems Biology and Its Implications for Huntington Disease Research

Huntington's disease (HD) is a progressive, fatal neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. The precise mechanisms of HD progression are poorly understood; however, it is known that there is an expansion of the trinucleotide cytosine-adenine-guanine (CAG) repeat in the Huntingtin gene. Important new strategies are of paramount importance to identify early biomarkers with predictive value for intervening in disease progression at a stage when cellular dysfunction has not progressed irreversibly. Metabolomics is the study of global metabolite profiles in a system (cell, tissue, or organism) under certain conditions and is becoming an essential tool for the systemic characterization of metabolites to provide a snapshot of the functional and pathophysiological states of an organism and support disease diagnosis and biomarker discovery. This review briefly highlights the historical progress of metabolomic methodologies, followed by a more detailed review of the use of metabolomics in HD research to enable a greater understanding of the pathogenesis, its early prediction, and finally the main technical platforms in the field of metabolomics.