Plasma TDP-43 Reflects Cortical Neurodegeneration and Correlates with Neuropsychiatric Symptoms in Huntington's Disease

Small RNAs in plasma extracellular vesicles define biomarkers of premanifest changes in Huntington's disease

Despite the advances in the understanding of Huntington's disease (HD), there is a need for molecular biomarkers to categorize mutation carriers during the preclinical stage of the disease preceding functional decline. Small RNAs (sRNAs) are a promising source of biomarkers since their expression levels are highly sensitive to pathobiological processes. Here, using an optimized method for plasma extracellular vesicles (EVs) purification and an exhaustive analysis pipeline of sRNA sequencing data, we show that EV-sRNAs are downregulated early in mutation carriers and that this deregulation is associated with premanifest cognitive performance. Seven candidate sRNAs (tRF-Glu-CTC, tRF-Gly-GCC, miR-451a, miR-21-5p, miR-26a-5p, miR-27a-3p and let7a-5p) were validated in additional subjects, showing a significant diagnostic accuracy at premanifest stages. Of these, miR-21-5p was significantly decreased over time in a longitudinal study; and miR-21-5p and miR-26a-5p levels correlated with cognitive changes in the premanifest cohort. In summary, the present results suggest that deregulated plasma EV-sRNAs define an early biosignature in mutation carriers with specific species highlighting the progression and cognitive changes occurring at the premanifest stage.

Pathomechanisms of behavioral abnormalities in Huntington disease: an update

Huntington disease (HD), a devastating autosomal-dominant neurodegenerative disease caused by an expanded CAG trinucleotide repeat, is clinically characterized by a triad of symptoms including involuntary motions, behavior problems and cognitive deficits. Behavioral symptoms with anxiety, irritability, obsessive-compulsive behaviors, apathy and other neuropsychiatric symptoms, occurring in over 50% of HD patients are important features of this disease and contribute to impairment of quality of life, but their pathophysiology is poorly understood. Behavior problems, more frequent than depression, can be manifest before obvious motor symptoms and occur across all HD stages, usually correlated with duration of illness. While specific neuropathological data are missing, the relations between gene expression and behavior have been elucidated in transgenic models of HD. Disruption of interneuronal communications, with involvement of prefronto-striato-thalamic networks and hippocampal dysfunctions produce deficits in multiple behavioral domains. These changes that have been confirmed by multistructural neuroimaging studies are due to a causal cascade linking molecular pathologies (glutamate-mediated excitotoxicity, mitochondrial dysfunctions inducing multiple biochemical and structural alterations) and deficits in multiple behavioral domains. The disruption of large-scale connectivities may explain the variability of behavior profiles and is useful in understanding the biological backgrounds of functional decline in HD. Such findings offer new avenues for targeted treatments in terms of minimizing neurobehavioral impairment in HD.

SERUM TRANSACTIVE RESPONSE DNA BINDING PROTEIN 43 ASSOCIATES WITH POOR SHORT-TERM NEUROLOGIC OUTCOME AFTER RETURN OF SPONTANEOUS CIRCULATION FOLLOWING CARDIAC ARREST

ABSTRACT

Objective : To explore the association of serum transactive response DNA binding protein 43 (TDP-43) with 28-day poor neurologic outcome in patients with return of spontaneous circulation (ROSC) after cardiac arrest. Methods : We performed a study between January and December 2023. Eligible patients with ROSC following cardiac arrest were enrolled. Their baseline characteristics were collected, and serum levels of TDP-43, tumor necrosis factor-α, interleukin-6 and 10, C-reactive protein, and neuron-specific enolase (NSE) at 24 h after ROSC were measured. The neurologic function was assessed by the cerebral performance category scores on day 28 after ROSC. Results : A total of 92 patients were included, with 51 and 41 patients in the good and poor neurologic outcome groups, respectively. Serum TDP-43 was significantly higher in the poor than the good neurologic outcome group ( P < 0.05). Univariate and multivariate logistic regression analyses showed that TDP-43, Witnessed CA, IL-6, and NSE were associated with poor 28-day neurologic outcome (all P < 0.05). Restricted cubic spline analysis revealed that TDP-43 at the serum level of 11.64 pg/mL might be an ideal cutoff value for distinguishing between good and poor neurologic outcomes. Area under curve of serum TDP-43 (AUC = 0.78) was close to that of serum NSE (AUC = 0.82). A dynamic nomogram prediction model that combined TDP-43, Witnessed CA, IL-6, and NSE was constructed and validated. Conclusion : Elevated serum TDP-43 level was associated with and could be used together with Witnessed CA, IL-6, and NSE to predict poor 28-day neurologic outcome in patients after ROSC following cardiac arrest.

In vivo diagnosis of TDP-43 proteinopathies: in search of biomarkers of clinical use

TDP-43 proteinopathies are a heterogeneous group of neurodegenerative disorders that share the presence of aberrant, misfolded and mislocalized deposits of the protein TDP-43, as in the case of amyotrophic lateral sclerosis and some, but not all, pathological variants of frontotemporal dementia. In recent years, many other diseases have been reported to have primary or secondary TDP-43 proteinopathy, such as Alzheimer's disease, Huntington's disease or the recently described limbic-predominant age-related TDP-43 encephalopathy, highlighting the need for new and accurate methods for the early detection of TDP-43 proteinopathy to help on the stratification of patients with overlapping clinical diagnosis. Currently, TDP-43 proteinopathy remains a post-mortem pathologic diagnosis. Although the main aim is to determine the pathologic TDP-43 proteinopathy in the central nervous system (CNS), the ubiquitous expression of TDP-43 in biofluids and cells outside the CNS facilitates the use of other accessible target tissues that might reflect the potential TDP-43 alterations in the brain. In this review, we describe the main developments in the early detection of TDP-43 proteinopathies, and their potential implications on diagnosis and future treatments.

Molecular Investigations of Protein Aggregation in the Pathogenesis of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disorder characterized by selective loss of lower and upper motor neurons (MNs) in the brain and spinal cord, resulting in paralysis and eventually death due to respiratory insufficiency. Although the fundamental physiological mechanisms underlying ALS are not completely understood, the key neuropathological hallmarks of ALS pathology are the aggregation and accumulation of ubiquitinated protein inclusions within the cytoplasm of degenerating MNs. Herein, we discuss recent insights into the molecular mechanisms that lead to the accumulation of protein aggregates in ALS. This will contribute to a better understanding of the pathophysiology of the disease and may open novel avenues for the development of therapeutic strategies.

A Glimpse of Molecular Biomarkers in Huntington's Disease

Huntington's disease (HD) is a devastating neurodegenerative disorder that is caused by an abnormal expansion of CAG repeats in the Huntingtin (HTT) gene. Although the main symptomatology is explained by alterations at the level of the central nervous system, predominantly affecting the basal ganglia, a peripheral component of the disease is being increasingly acknowledged. Therefore, the manifestation of the disease is complex and variable among CAG expansion carriers, introducing uncertainty in the appearance of specific signs, age of onset and severity of disease. The monogenic nature of the disorder allows a precise diagnosis, but the use of biomarkers with prognostic value is still needed to achieve clinical management of the patients in an individual manner. In addition, we need tools to evaluate the patient's response to potential therapeutic approaches. In this review, we provide a succinct summary of the most interesting molecular biomarkers that have been assessed in patients, mostly obtained from body fluids such as cerebrospinal fluid, peripheral blood and saliva.