Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Promising use of metformin in treating neurological disorders: biomarker-guided therapies

Neurological disorders are a diverse group of conditions that affect the nervous system and include neurodegenerative diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease), cerebrovascular conditions (stroke), and neurodevelopmental disorders (autism spectrum disorder). Although they affect millions of individuals around the world, only a limited number of effective treatment options are available today. Since most neurological disorders express mitochondria-related metabolic perturbations, metformin, a biguanide type II antidiabetic drug, has attracted a lot of attention to be repurposed to treat neurological disorders by correcting their perturbed energy metabolism. However, controversial research emerges regarding the beneficial/detrimental effects of metformin on these neurological disorders. Given that most neurological disorders have complex etiology in their pathophysiology and are influenced by various risk factors such as aging, lifestyle, genetics, and environment, it is important to identify perturbed molecular functions that can be targeted by metformin in these neurological disorders. These molecules can then be used as biomarkers to stratify subpopulations of patients who show distinct molecular/pathological properties and can respond to metformin treatment, ultimately developing targeted therapy. In this review, we will discuss mitochondria-related metabolic perturbations and impaired molecular pathways in these neurological disorders and how these can be used as biomarkers to guide metformin-responsive treatment for the targeted therapy to treat neurological disorders.

Increased retinal venule diameter as a prognostic indicator for recurrent cerebrovascular events: a prospective observational study

Microvasculature of the retina is considered an alternative marker of cerebral vascular risk in healthy populations. However, the ability of retinal vasculature changes, specifically focusing on retinal vessel diameter, to predict the recurrence of cerebrovascular events in patients with ischemic stroke has not been determined comprehensively. While previous studies have shown a link between retinal vessel diameter and recurrent cerebrovascular events, they have not incorporated this information into a predictive model. Therefore, this study aimed to investigate the relationship between retinal vessel diameter and subsequent cerebrovascular events in patients with acute ischemic stroke. Additionally, we sought to establish a predictive model by combining retinal veessel diameter with traditional risk factors. We performed a prospective observational study of 141 patients with acute ischemic stroke who were admitted to the First Affiliated Hospital of Jinan University. All of these patients underwent digital retinal imaging within 72 hours of admission and were followed up for 3 years. We found that, after adjusting for related risk factors, patients with acute ischemic stroke with mean arteriolar diameter within 0.5-1.0 disc diameters of the disc margin (MAD0.5-1.0DD) of ≥ 74.14 μm and mean venular diameter within 0.5-1.0 disc diameters of the disc margin (MVD0.5-1.0DD) of ≥ 83.91 μm tended to experience recurrent cerebrovascular events. We established three multivariate Cox proportional hazard regression models: model 1 included traditional risk factors, model 2 added MAD0.5-1.0DD to model 1, and model 3 added MVD0.5-1.0DD to model 1. Model 3 had the greatest potential to predict subsequent cerebrovascular events, followed by model 2, and finally model 1. These findings indicate that combining retinal venular or arteriolar diameter with traditional risk factors could improve the prediction of recurrent cerebrovascular events in patients with acute ischemic stroke, and that retinal imaging could be a useful and non-invasive method for identifying high-risk patients who require closer monitoring and more aggressive management.

Vagal pathways for systemic regulation of glucose metabolism

Maintaining blood glucose at an appropriate physiological level requires precise coordination of multiple organs and tissues. The vagus nerve bidirectionally connects the central nervous system with peripheral organs crucial to glucose mobilization, nutrient storage, and food absorption, thereby presenting a key pathway for the central control of blood glucose levels. However, the precise mechanisms by which vagal populations that target discrete tissues participate in glucoregulation are much less clear. Here we review recent advances unraveling the cellular identity, neuroanatomical organization, and functional contributions of both vagal efferents and vagal afferents in the control of systemic glucose metabolism. We focus on their involvement in relaying glucoregulatory cues from the brain to peripheral tissues, particularly the pancreatic islet, and by sensing and transmitting incoming signals from ingested food to the brain. These recent findings - largely driven by advances in viral approaches, RNA sequencing, and cell-type selective manipulations and tracings - have begun to clarify the precise vagal neuron populations involved in the central coordination of glucose levels, and raise interesting new possibilities for the treatment of glucose metabolism disorders such as diabetes.

Artificial intelligence-assisted repair of peripheral nerve injury: a new research hotspot and associated challenges

Artificial intelligence can be indirectly applied to the repair of peripheral nerve injury. Specifically, it can be used to analyze and process data regarding peripheral nerve injury and repair, while study findings on peripheral nerve injury and repair can provide valuable data to enrich artificial intelligence algorithms. To investigate advances in the use of artificial intelligence in the diagnosis, rehabilitation, and scientific examination of peripheral nerve injury, we used CiteSpace and VOSviewer software to analyze the relevant literature included in the Web of Science from 1994-2023. We identified the following research hotspots in peripheral nerve injury and repair: (1) diagnosis, classification, and prognostic assessment of peripheral nerve injury using neuroimaging and artificial intelligence techniques, such as corneal confocal microscopy and coherent anti-Stokes Raman spectroscopy; (2) motion control and rehabilitation following peripheral nerve injury using artificial neural networks and machine learning algorithms, such as wearable devices and assisted wheelchair systems; (3) improving the accuracy and effectiveness of peripheral nerve electrical stimulation therapy using artificial intelligence techniques combined with deep learning, such as implantable peripheral nerve interfaces; (4) the application of artificial intelligence technology to brain-machine interfaces for disabled patients and those with reduced mobility, enabling them to control devices such as networked hand prostheses; (5) artificial intelligence robots that can replace doctors in certain procedures during surgery or rehabilitation, thereby reducing surgical risk and complications, and facilitating postoperative recovery. Although artificial intelligence has shown many benefits and potential applications in peripheral nerve injury and repair, there are some limitations to this technology, such as the consequences of missing or imbalanced data, low data accuracy and reproducibility, and ethical issues (e.g., privacy, data security, research transparency). Future research should address the issue of data collection, as large-scale, high-quality clinical datasets are required to establish effective artificial intelligence models. Multimodal data processing is also necessary, along with interdisciplinary collaboration, medical-industrial integration, and multicenter, large-sample clinical studies.

Dual-directional regulation of spinal cord injury and the gut microbiota

There is increasing evidence that the gut microbiota affects the incidence and progression of central nervous system diseases via the brain-gut axis. The spinal cord is a vital important part of the central nervous system; however, the underlying association between spinal cord injury and gut interactions remains unknown. Recent studies suggest that patients with spinal cord injury frequently experience intestinal dysfunction and gut dysbiosis. Alterations in the gut microbiota can cause disruption in the intestinal barrier and trigger neurogenic inflammatory responses which may impede recovery after spinal cord injury. This review summarizes existing clinical and basic research on the relationship between the gut microbiota and spinal cord injury. Our research identified three key points. First, the gut microbiota in patients with spinal cord injury presents a key characteristic and gut dysbiosis may profoundly influence multiple organs and systems in patients with spinal cord injury. Second, following spinal cord injury, weakened intestinal peristalsis, prolonged intestinal transport time, and immune dysfunction of the intestine caused by abnormal autonomic nerve function, as well as frequent antibiotic treatment, may induce gut dysbiosis. Third, the gut microbiota and associated metabolites may act on central neurons and affect recovery after spinal cord injury; cytokines and the Toll-like receptor ligand pathways have been identified as crucial mechanisms in the communication between the gut microbiota and central nervous system. Fecal microbiota transplantation, probiotics, dietary interventions, and other therapies have been shown to serve a neuroprotective role in spinal cord injury by modulating the gut microbiota. Therapies targeting the gut microbiota or associated metabolites are a promising approach to promote functional recovery and improve the complications of spinal cord injury.

Soluble p75 neurotrophic receptor as a reliable biomarker in neurodegenerative diseases: what is the evidence?

Neurodegenerative diseases are often misdiagnosed, especially when the diagnosis is based solely on clinical symptoms. The p75 neurotrophic receptor (p75NTR) has been studied as an index of sensory and motor nerve development and maturation. Its cleavable extracellular domain (ECD) is readily detectable in various biological fluids including plasma, serum and urine. There is evidence for increased p75NTR ECD levels in neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis, age-related dementia, schizophrenia, and diabetic neuropathy. Whether p75NTR ECD could be used as a biomarker for diagnosis and/or prognosis in these disorders, and whether it could potentially lead to the development of targeted therapies, remains an open question. In this review, we present and discuss published studies that have evaluated the relevance of this emerging biomarker in the context of various neurodegenerative diseases. We also highlight areas that require further investigation to better understand the role of p75NTR ECD in the clinical diagnosis and management of neurodegenerative disorders.

Trends in Research Payments for Diabetic Macular Edema from 2015 to 2021

Purpose

To evaluate characteristics of research payments for diabetic macular edema (DME) studies and correlations to current management trends.

Design

Retrospective cross-sectional study.

Subjects

Research payments for DME.

Methods

Studies with keywords of "diabetic macular edema" or "DME" in the title were extracted from the Centers of Medicare & Medicaid Services Open Payments database from 2015 to 2021. Recipients, payors, and payment amounts were identified. Industry funding was compared with public research funding by the National Eye Institute (NEI).

Main Outcome Measures

Trends and total value of industry and public fundings for DME from 2015 to 2021.

Results

From 2015 to 2021, 451 beneficiaries received 6062 industry payments for a total of $120 148 997.41 for DME-related research. The total value of industry funding increased from $8 225 859.08 in 2015 to $50 092 778.45 in 2021. Of the 6062 industry payments, 5367 (88.5%) were reported by male recipients compared with 695 (11.5%) female beneficiaries. Payments to female recipients increased from 60 (7.1%) in 2015 to 335 (13.7%) in 2021. In comparison, public funding for DME-related research from the NEI was comprised of $18 863 266.00 to 17 principal investigators from 2015 to 2021. The total value of public funding increased from $973 590.00 in 2015 to $3 354 376.00 in 2021. Of 59 public research payments, 46 (78.0%) were reported by male recipients and 13 (22.0%) by female recipients. Payments to female recipients increased from 1 (25.0%) in 2015 to 3 (30.0%) in 2021. The most highly invested product by industry were anti-VEGF agents, accounting for $89 955 595.20 (74.9%) of total payment value.

Conclusions

There was an increase in both industry and public-sponsored funding for DME-related research from 2015 to 2021. There seemed to be a possible discrepancy in both industry and public funding based on sex for DME studies during the study period.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Cell metabolism pathways involved in the pathophysiological changes of diabetic peripheral neuropathy

Diabetic peripheral neuropathy is a common complication of diabetes mellitus. Elucidating the pathophysiological metabolic mechanism impels the generation of ideal therapies. However, existing limited treatments for diabetic peripheral neuropathy expose the urgent need for cell metabolism research. Given the lack of comprehensive understanding of energy metabolism changes and related signaling pathways in diabetic peripheral neuropathy, it is essential to explore energy changes and metabolic changes in diabetic peripheral neuropathy to develop suitable treatment methods. This review summarizes the pathophysiological mechanism of diabetic peripheral neuropathy from the perspective of cellular metabolism and the specific interventions for different metabolic pathways to develop effective treatment methods. Various metabolic mechanisms (e.g., polyol, hexosamine, protein kinase C pathway) are associated with diabetic peripheral neuropathy, and researchers are looking for more effective treatments through these pathways.

Exosomes derived from impaired liver aggravate alveolar bone loss via shuttle of Fasn in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) exacerbates irreversible bone loss in periodontitis, but the mechanism of impaired bone regeneration caused by the abnormal metabolic process of T2DM remains unclear. Exosomes are regarded as the critical mediator in diabetic impairment of regeneration via organ or tissue communication. Here, we find that abnormally elevated exosomes derived from metabolically impaired liver in T2DM are significantly enriched in the periodontal region and induced pyroptosis of periodontal ligament cells (PDLCs). Mechanistically, fatty acid synthase (Fasn), the main differentially expressed molecule in diabetic exosomes results in ectopic fatty acid synthesis in PDLCs and activates the cleavage of gasdermin D. Depletion of liver Fasn effectively mitigates pyroptosis of PDLCs and alleviates bone loss. Our findings elucidate the mechanism of exacerbated bone loss in diabetic periodontitis and reveal the exosome-mediated organ communication in the "liver-bone" axis, which shed light on the prevention and treatment of diabetic bone disorders in the future.