Trehalose Inhibits Aβ Generation and Plaque Formation in Alzheimer's Disease

Targeting lysosomal quality control as a therapeutic strategy against aging and diseases

Previously, lysosomes were primarily referred to as the digestive organelles and recycling centers within cells. Recent discoveries have expanded the lysosomal functional scope and revealed their critical roles in nutrient sensing, epigenetic regulation, plasma membrane repair, lipid transport, ion homeostasis, and cellular stress response. Lysosomal dysfunction is also found to be associated with aging and several diseases. Therefore, function of macroautophagy, a lysosome-dependent intracellular degradation system, has been identified as one of the updated twelve hallmarks of aging. In this review, we begin by introducing the concept of lysosomal quality control (LQC), which is a cellular machinery that maintains the number, morphology, and function of lysosomes through different processes such as lysosomal biogenesis, reformation, fission, fusion, turnover, lysophagy, exocytosis, and membrane permeabilization and repair. Next, we summarize the results from studies reporting the association between LQC dysregulation and aging/various disorders. Subsequently, we explore the emerging therapeutic strategies that target distinct aspects of LQC for treating diseases and combatting aging. Lastly, we underscore the existing knowledge gap and propose potential avenues for future research.

Unlocking Trehalose's versatility: A comprehensive Journey from biosynthesis to therapeutic applications

For over forty years, a sugar of rare configuration known as trehalose (two molecules of glucose linked at their 1-carbons), has been recognised for more than just its roles as a storage compound. The ability of trehalose to protect an extensive range of biological materials, for instance cell lines, tissues, proteins and DNA, has sparked considerable interest in the biotechnology and pharmaceutical industries. Currently, trehalose is now being investigated as a promising therapeutic candidate for human use, as it has shown potential to reduce disease severity in various experimental models. Despite its diverse biological effects, the precise mechanism underlying this observation remain unclear. Therefore, this review delves into the significance of trehalose biosynthesis pathway in the development of novel drug, investigates the inhibitors of trehalose synthesis and evaluates the binding efficiency of T6P with TPS1. Additionally, it also emphasizes the knowledge about the protective effect of trehalose on modulation of autophagy, combating viral infections, addressing the conditions like cancer and neurodegenerative diseases based on the recent advancement. Furthermore, review also highlight the trehalose's emerging role as a surfactant in delivering monoclonal antibodies that will further broadening its potential application in biomedicines.

Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

Effect of trehalose on mortality and disease severity in ICU-admitted patients: Protocol for a triple-blind, randomized, placebo-controlled clinical trial

Background

Improvement in organ failure in intensive care unit (ICU) patients is accompanied by lower mortality rate. A disaccharide, trehalose is a candidate to improve organ failure and survival by autophagy induction and enhancing oxidative stress defense. The aim of this study is to assess the effectiveness of trehalose in improving clinical outcome and reducing mortality in ICU patients.

Methods

a triple-blind, randomized, placebo-controlled, two arm, parallel-group, superiority clinical trial will enroll 200 ICU-admitted patients at Imam Reza hospital, Mashhad, Iran. The patients will be randomly allocated to receive either a 100 ml solution of 15 % trehalose or normal saline intravenously. Primary outcomes include ICU mortality and 60-day mortality, while secondary outcomes focus on blood parameters on day 5 and length of hospital/ICU stay.

Conclusion

Trehalose has demonstrated beneficial effects in diverse patients; however, no study has evaluated its effect in all ICU-admitted patients. Consequently, this study provides an opportunity to investigate whether trehalose's anti-inflammatory effects, mediated by inducing autophagy and enhancing oxidative stress defense, can play a role in reducing mortality and improving clinical outcomes in the critically ill patients. If successful, trehalose could offer a potential therapeutic approach in the ICU setting.

Protective effect of trehalose sugar on amyloid-membrane interactions using BLM electrophysiology

Alzheimer's disease (AD) is a neurodegenerative disease characterized by dementia and memory loss in the elderly population. The amyloid-β peptide (Aβ) is one of the main pathogenic factors in AD and is known to cause damage to neuronal cellular membranes. There is no cure currently available for AD, and new approaches, including preventive strategies, are highly desirable. In this work, we explore the possibility of protecting neuronal membranes from amyloid-induced damage with naturally existing sugar trehalose. Trehalose has been shown to protect plant cellular membranes in extreme conditions and modify Aβ misfolding. We hypothesize that trehalose can protect the neuronal membrane from amyloid toxicity. In this work, we studied the protective effect of trehalose against Aβ1-42-induced damage in model lipid membranes (DPPC/POPC/cholesterol) using atomic force microscopy and black lipid membrane electrophysiology. Our results demonstrate that Aβ1-42 damaged membranes and led to ionic current leakage across these membranes due to the formation of various defects and pores. The presence of trehalose reduced the ion current across membranes caused by Aβ1-42 peptide damage, thus efficiently protecting the membranes. These findings suggest that the trehalose sugar can potentially be useful in protecting neuronal membranes against amyloid toxicity in AD.

Alimentary Treatment with Trehalose in a Pharmacological Model of Alzheimer's Disease in Mice: Effects of Different Dosages and Treatment Regimens

In the treatment of experimental neurodegeneration with disaccharide trehalose, various regimens are used, predominantly a 2% solution, drunk for several weeks. We studied the effects of different regimens of dietary trehalose treatment in an amyloid-β (Aβ) 25-35-induced murine model of Alzheimer's disease (AD). Aβ-treated mice received 2% trehalose solution daily, 4% trehalose solution daily (continuous mode) or every other day (intermittent mode), to drink for two weeks. We revealed the dose-dependent effects on autophagy activation in the frontal cortex and hippocampus, and the restoration of behavioral disturbances. A continuous intake of 4% trehalose solution caused the greatest activation of autophagy and the complete recovery of step-through latency in the passive avoidance test that corresponds to associative long-term memory and learning. This regimen also produced an anxiolytic effect in the open field. The effects of all the regimens studied were similar in Aβ load, neuroinflammatory response, and neuronal density in the frontal cortex and hippocampus. Trehalose successfully restored these parameters to the levels of the control group. Thus, high doses of trehalose had increased efficacy towards cognitive impairment in a model of early AD-like pathology. These findings could be taken into account for translational studies and the development of clinical approaches for AD therapy using trehalose.

Neuroprotective effects of chaperone-mediated autophagy in neurodegenerative diseases

ABSTRACT

Chaperone-mediated autophagy is one of three types of autophagy and is characterized by the selective degradation of proteins. Chaperone-mediated autophagy contributes to energy balance and helps maintain cellular homeostasis, while providing nutrients and support for cell survival. Chaperone-mediated autophagy activity can be detected in almost all cells, including neurons. Owing to the extreme sensitivity of neurons to their environmental changes, maintaining neuronal homeostasis is critical for neuronal growth and survival. Chaperone-mediated autophagy dysfunction is closely related to central nervous system diseases. It has been shown that neuronal damage and cell death are accompanied by chaperone-mediated autophagy dysfunction. Under certain conditions, regulation of chaperone-mediated autophagy activity attenuates neurotoxicity. In this paper, we review the changes in chaperone-mediated autophagy in neurodegenerative diseases, brain injury, glioma, and autoimmune diseases. We also summarize the most recent research progress on chaperone-mediated autophagy regulation and discuss the potential of chaperone-mediated autophagy as a therapeutic target for central nervous system diseases.

Exploiting sweet relief for preeclampsia by targeting autophagy-lysosomal machinery and proteinopathy

The etiology of preeclampsia (PE), a severe complication of pregnancy with several clinical manifestations and a high incidence of maternal and fetal morbidity and mortality, remains unclear. This issue is a major hurdle for effective treatment strategies. We recently demonstrated that PE exhibits an Alzheimer-like etiology of impaired autophagy and proteinopathy in the placenta. Targeting of these pathological pathways may be a novel therapeutic strategy for PE. Stimulation of autophagy with the natural disaccharide trehalose and its lacto analog lactotrehalose in hypoxia-exposed primary human trophoblasts restored autophagy, inhibited the accumulation of toxic protein aggregates, and restored the ultrastructural features of autophagosomes and autolysosomes. Importantly, trehalose and lactotrehalose inhibited the onset of PE-like features in a humanized mouse model by normalizing autophagy and inhibiting protein aggregation in the placenta. These disaccharides restored the autophagy-lysosomal biogenesis machinery by increasing nuclear translocation of the master transcriptional regulator TFEB. RNA-seq analysis of the placentas of mice with PE indicated the normalization of the PE-associated transcriptome profile in response to trehalose and lactotrehalose. In summary, our results provide a novel molecular rationale for impaired autophagy and proteinopathy in patients with PE and identify treatment with trehalose and its lacto analog as promising therapeutic options for this severe pregnancy complication.

Salivary biomarkers: The early diagnosis of Alzheimer's disease

The precise identification of Alzheimer's disease and other prevalent neurodegenerative diseases remains a difficult issue that requires the development of early detection of the disease and inexpensive biomarkers that can replace the present cerebrospinal fluid and imaging biomarkers. Blood biomarkers, such as amyloid and neurofilament light, have been emphasized as an important and practical tool in a testing or examination procedure thanks to advancements in ultra-sensitive detection techniques. Although saliva is not currently being researched for neurodegenerative diseases, it is an important source of biomarkers that can be used for the identification of diseases and has some advantages over other biofluids. While this may be true for most people, getting saliva from elderly people presents some significant challenges. In this overview, we will first discuss how saliva is created and how aging-related illnesses may affect the amount and kind of saliva produced. The findings support the use of salivary amyloid protein, tau species, and novel biomarkers in the diagnosis of Alzheimer's disease.

Trehalose improves the movement ability of AβarcDrosophila by restoring the damaged mitochondria

Background

The deposition of Aβ42 has been regarded as one of the important pathological features of Alzheimer's disease (AD). However, drug development for Aβ42 toxicity has been progressed slowly.

Objective

Our aim was to introduce the effect and related mechanism of trehalose on an Aβarc (arctic mutant Aβ42) Drosophila AD model.

Methods

The human Aβarc was expressed in Drosophila to construct the AD model. Trehalose was added to the culture vial. The movement ability was determined by detecting climbing ability and flight ability. Enzyme-linked immunosorbent assay was used to detect the levels of Aβarc, ATP, and lactate. Electron microscopy assay, mitochondrial membrane potential assay, and mitochondrial respiration assay were used to assess the mitochondrial structure and function.

Results

Trehalose strongly improved the movement ability of Aβarc Drosophila in a concentration gradient-dependent manner. Furthermore, trehalose increased the content of ATP and decreased the content of Aβarc and lactate both in the brain and thorax of Aβarc Drosophila. More importantly, the mitochondrial structure and function were greatly improved by trehalose treatment in Aβarc Drosophila.

Conclusion

Trehalose improves movement ability at least partly by reducing the Aβarc level and restoring the mitochondrial structure and function in Aβarc Drosophila.

miR-146a aggravates cognitive impairment and Alzheimer disease-like pathology by triggering oxidative stress through MAPK signaling

INTRODUCTION

Mir-146a-5p has been widely recognized as a critical regulatory element in the immune response. However, recent studies have shown that miR-146a-5p may also be involved in the development of Alzheimer disease (AD). Regrettably, the related mechanisms are poorly understood. Here, we investigated the effects of miR-146a in mice models and SH-SY5Y cells treated with amyloid β (Aβ)1-42.

METHODS

To create a model of AD, SH-SY5Y cells were treated with Aβ1-42 and mice received intracerebroventricular injections of Aβ1-42. Then, the transcriptional levels of miR-146a were estimated by real-time PCR. We transiently transfected the miR-146a-5p mimic/inhibitor into cells and mice to study the role of miR-146a. The role of signaling pathways including p38 and reactive oxygen species (ROS) was studied by using specific inhibitors. Aβ and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aβ expression was analyzed by immunofluorescence and histochemical examinations.

RESULTS

Aβ1-42-stimulated SH-SY5Y cells displayed increased transcriptional levels of miR-146a and APP. Moreover, the p38 MAPK signaling pathway and ROS production were activated upon stimulation with a miR-146a-5p mimic. However, treatment with a miR-146a-5p inhibitor decreased the levels of APP, ROS, and p-p38 MAPK. A similar phenomenon was also observed in the animals treated with Aβ1-42, in which miR-146a upregulation increased the expression of Aβ, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aβ deposition and ROS accumulation via the p-p38 signaling pathway.

CONCLUSIONS

Our research demonstrates that miR-146a-5pa increases Aβ deposition by triggering oxidative stress through activation of MAPK signaling.

Profiling neuroprotective potential of trehalose in animal models of neurodegenerative diseases: a systematic review

Trehalose, a unique nonreducing crystalline disaccharide, is a potential disease-modifying treatment for neurodegenerative diseases associated with protein misfolding and aggregation due to aging, intrinsic mutations, or autophagy dysregulation. This systematic review summarizes the effects of trehalose on its underlying mechanisms in animal models of selected neurodegenerative disorders (tau pathology, synucleinopathy, polyglutamine tract, and motor neuron diseases). All animal studies on neurodegenerative diseases treated with trehalose published in Medline (accessed via EBSCOhost) and Scopus were considered. Of the 2259 studies screened, 29 met the eligibility criteria. According to the SYstematic Review Center for Laboratory Animal Experiment (SYRCLE) risk of bias tool, we reported 22 out of 29 studies with a high risk of bias. The present findings support the purported role of trehalose in autophagic flux and protein refolding. This review identified several other lesser-known pathways, including modifying amyloid precursor protein processing, inhibition of reactive gliosis, the integrity of the blood-brain barrier, activation of growth factors, upregulation of the downstream antioxidant signaling pathway, and protection against mitochondrial defects. The absence of adverse events and improvements in the outcome parameters were observed in some studies, which supports the transition to human clinical trials. It is possible to conclude that trehalose exerts its neuroprotective effects through both direct and indirect pathways. However, heterogeneous methodologies and outcome measures across the studies rendered it impossible to derive a definitive conclusion. Translational studies on trehalose would need to clarify three important questions: 1) bioavailability with oral administration, 2) optimal time window to confer neuroprotective benefits, and 3) optimal dosage to confer neuroprotection.

Targeting lipophagy in macrophages improves repair in multiple sclerosis

Foamy macrophages containing abundant intracellular myelin remnants are an important pathological hallmark of multiple sclerosis. Reducing the intracellular lipid burden in foamy macrophages is considered a promising therapeutic strategy to induce a phagocyte phenotype that promotes central nervous system repair. Recent research from our group showed that sustained intracellular accumulation of myelin-derived lipids skews these phagocytes toward a disease-promoting and more inflammatory phenotype. Our data now demonstrate that disturbed lipophagy, a selective form of autophagy that helps with the degradation of lipid droplets, contributes to the induction of this phenotype. Stimulating autophagy using the natural disaccharide trehalose reduced the lipid load and inflammatory phenotype of myelin-laden macrophages. Importantly, trehalose was able to boost remyelination in the ex vivo brain slice model and the in vivo cuprizone-induced demyelination model. In summary, our results provide a molecular rationale for impaired metabolism of myelin-derived lipids in macrophages, and identify lipophagy induction as a promising treatment strategy to promote remyelination.Abbreviations: Baf: bafilomycin a1; BMDM: bone marrow-derived macrophage; CD68: CD68 antigen; CNS: central nervous system; LD: lipid droplet; LIPE/HSL: lipase, hormone sensitive; LPS: lipopolysaccharide; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MBP: myelin basic protein; MGLL: monoglyceride lipase; MS: multiple sclerosis; NO: nitric oxide; NOS2/iNOS: nitric oxide synthase 2, inducible; ORO: oil red o; PNPLA2: patatin-like phospholipase domain containing 2; PLIN2: perilipin 2; TEM: transmission electron microscopy; TFEB: transcription factor EB; TOH: trehalose.

Proteostasis unbalance in prion diseases: Mechanisms of neurodegeneration and therapeutic targets

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are progressive neurodegenerative disorders of the central nervous system that affect humans and animals as sporadic, inherited, and infectious forms. Similarly to Alzheimer's disease and other neurodegenerative disorders, any attempt to reduce TSEs' lethality or increase the life expectancy of affected individuals has been unsuccessful. Typically, the onset of symptoms anticipates the fatal outcome of less than 1 year, although it is believed to be the consequence of a decades-long process of neuronal death. The duration of the symptoms-free period represents by itself a major obstacle to carry out effective neuroprotective therapies. Prions, the infectious entities of TSEs, are composed of a protease-resistant protein named prion protein scrapie (PrP^Sc) from the prototypical TSE form that afflicts ovines. PrP^Sc misfolding from its physiological counterpart, cellular prion protein (PrP^C), is the unifying pathogenic trait of all TSEs. PrP^Sc is resistant to intracellular turnover and undergoes amyloid-like fibrillation passing through the formation of soluble dimers and oligomers, which are likely the effective neurotoxic entities. The failure of PrP^Sc removal is a key pathogenic event that defines TSEs as proteopathies, likewise other neurodegenerative disorders, including Alzheimer's, Parkinson's, and Huntington's disease, characterized by alteration of proteostasis. Under physiological conditions, protein quality control, led by the ubiquitin-proteasome system, and macroautophagy clears cytoplasm from improperly folded, redundant, or aggregation-prone proteins. There is evidence that both of these crucial homeostatic pathways are impaired during the development of TSEs, although it is still unclear whether proteostasis alteration facilitates prion protein misfolding or, rather, PrP^Sc protease resistance hampers cytoplasmic protein quality control. This review is aimed to critically analyze the most recent advancements in the cause-effect correlation between PrP^C misfolding and proteostasis alterations and to discuss the possibility that pharmacological restoring of ubiquitin-proteasomal competence and stimulation of autophagy could reduce the intracellular burden of PrP^Sc and ameliorate the severity of prion-associated neurodegeneration.

Trehalose Attenuates Learning and Memory Impairments in Aged Rats via Overexpression of miR-181c

MicroRNAs have been recognized as important regulators of the aging process. Trehalose, a natural disaccharide, displays protective effects against neuronal impairment through several mechanisms. However, little is known about the interactive effects of aging and trehalose on behavioral function and underlying miRNA expression patterns in the hippocampus of young and old rats. Male Wistar rats were divided into four groups. Two groups of aged (24 months) and young (4 months) rats were administered 2% trehalose solution for 30 days. Two other groups of aged and young rats received regular tap water. At the end of treatment, rats were assessed for cognitive behavior using the Morris water maze test. The expression level of miR-181c and mir-34c was also measured by qRT-PCR. We found that trehalose treatment reduced learning and memory impairment in old rats compared to control old animals (p < 0.05). In contrast, cognitive performance was not significantly improved in trehalose-treated young rats in comparison with young controls (p > 0.05). We also showed that the expression level of miR-181c was significantly increased in trehalose-treated rats (p < 0.01). However, analysis of miR-34c expression level indicated no significant difference between trehalose-treated old rats and non-treated old animals (p > 0.05). Our results indicated that trehalose treatment improved learning and memory function in aged rats by targeting miR-181c. Therefore, trehalose administration may provide a therapeutic strategy to ameliorate age-associated cognitive impairment.

Disaccharide Trehalose in Experimental Therapies for Neurodegenerative Disorders: Molecular Targets and Translational Potential

Induction of autophagy is a prospective approach to the treatment of neurodegeneration. In the recent decade, trehalose attracted special attention. It is an autophagy inducer with negligible adverse effects and is approved for use in humans according to FDA requirements. Trehalose has a therapeutic effect in various experimental models of diseases. This glucose disaccharide with a flexible α-1-1'-glycosidic bond has unique properties: induction of mTOR-independent autophagy (with kinase AMPK as the main target) and a chaperone-like effect on proteins imparting them natural spatial structure. Thus, it can reduce the accumulation of neurotoxic aberrant/misfolded proteins. Trehalose has an anti-inflammatory effect and inhibits detrimental oxidative stress partially owing to the enhancement of endogenous antioxidant defense represented by the Nrf2 protein. The disaccharide activates lysosome and autophagosome biogenesis pathways through the protein factors TFEB and FOXO1. Here we review various mechanisms of the neuroprotective action of trehalose and touch on the possibility of pleiotropic effects. Current knowledge about specific features of trehalose pharmacodynamics is discussed. The neuroprotective effects of trehalose in animal models of major neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases are examined too. Attention is given to translational transition to clinical trials of this drug, especially oral and parenteral routes of administration. Besides, the possibility of enhancing the therapeutic benefit via a combination of mTOR-dependent and mTOR-independent autophagy inducers is analyzed. In general, trehalose appears to be a promising multitarget tool for the inhibition of experimental neurodegeneration and requires thorough investigation of its clinical capabilities.

Regulation of the Human IL-10RB Gene Expression by Sp8 and Sp9

BACKGROUND

Interleukin-10 (IL-10) is a classic anti-inflammatory cytokine that exerts its effects via the receptor complexes IL-10RA and IL-10RB. Loss of IL-10RB results in many diseases. Moreover, IL-10RB is closely associated with neuronal survival and synaptic formation. However, the regulation of IL-10RB gene expression remains elusive.

OBJECTIVE

To investigate whether the expression of IL-10RB gene is increased in brain of Alzheimer's disease (AD) and its transcriptional regulation.

METHODS

We examined the gene expression of AD patient brain from public database and detected the protein expression of AD model mouse brain by western blot. We constructed a variety of reporter gene plasmids with different lengths or mutation sites, tested the promoter activity and defined the functional region of the promoter with the luciferase reporter assay. The protein-DNA binding between transcription factors and the promoter was analyzed using chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA).

RESULTS

We found that the IL-10RB is elevated in the brain of AD patient and AD model mice. The minimal promoter of the IL-10RB gene is located in the -90 to +51 bp region (relative to the transcriptional start site) and is sufficient for high-level expression of the IL-10RB gene. Transcription factors Sp8 and Sp9 bind to the IL-10RB promoter in vitro. The overexpression or knockdown of Sp8 and Sp9 affected the IL-10RB promoter activity and its gene expression.

CONCLUSION

Our study functionally characterized the promoter of the IL-10RB gene and demonstrated that Sp8 and Sp9 regulated its expression.

Neuroprotective Effects of Oligosaccharides in Rehmanniae Radix on Transgenic Caenorhabditis elegans Models for Alzheimer’s Disease

Rehmanniae Radix (RR, the dried tuberous roots of Rehmannia glutinosa (Gaertn.) DC.) is an important traditional Chinese medicine distributed in Henan, Hebei, Inner Mongolia, and Northeast in China. RR is frequently used to treat diabetes mellitus, cardiovascular disease, osteoporosis and aging-related diseases in a class of prescriptions. The oligosaccharides and catalpol in RR have been confirmed to have neuroprotective effects. However, there are few studies on the anti-Alzheimer’s disease (AD) effect of oligosaccharides in Rehmanniae Radix (ORR). The chemical components and pharmacological effects of dried Rehmannia Radix (DRR) and prepared Rehmannia Radix (PRR) are different because of the different processing methods. ORR has neuroprotective potential, such as improving learning and memory in rats. Therefore, this study aimed to prove the importance of oligosaccharides in DRR (ODRR) and PRR (OPRR) for AD based on the Caenorhabditis elegans (C. elegans) model and the different roles of ODRR and OPRR in the treatment of AD. In this study, we used paralysis assays, lifespan and stress resistance assays, bacterial growth curve, developmental and behavioral parameters, and ability of learning and memory to explore the effects of ODRR and OPRR on anti-AD and anti-aging. Furthermore, the accumulation of reactive oxygen species (ROS); deposition of Aβ; and expression of amy-1, sir-2.1, daf-16, sod-3, skn-1, and hsp-16.2 were analyzed to confirm the efficacy of ODRR and OPRR. OPRR was more effective than ODRR in delaying the paralysis, improving learning ability, and prolonging the lifespan of C. elegans. Further mechanism studies showed that the accumulation of ROS, aggregation, and toxicity of Aβ were reduced, suggesting that ORR alleviated Aβ-induced toxicity, in part, through antioxidant activity and Aβ aggregation inhibiting. The expression of amy-1 was downregulated, and sir-2.1, daf-16, sod-3, and hsp-16.2 were upregulated. Thus, ORR could have a possible therapeutic effect on AD by modulating the expression of amy-1, sir-2.1, daf-16, sod-3, and hsp-16.2. Furthermore, ORR promoted the nuclear localization of daf-16 and further increased the expression of sod-3 and hsp-16.2, which significantly contributed to inhibiting the Aβ toxicity and enhancing oxidative stress resistance. In summary, the study provided a new idea for the development of ORR.

Functional and transcriptional profiling of microglial activation during the chronic phase of TBI identifies an age-related driver of poor outcome in old mice

Elderly patients with traumatic brain injury (TBI) have greater mortality and poorer outcomes than younger individuals. The extent to which old age alters long-term recovery and chronic microglial activation after TBI is unknown, and evidence for therapeutic efficacy in aged mice is sorely lacking. The present study sought to identify potential inflammatory mechanisms underlying age-related outcomes late after TBI. Controlled cortical impact was used to induce moderate TBI in young and old male C57BL/6 mice. At 12 weeks post-injury, aged mice exhibited higher mortality, poorer functional outcomes, larger lesion volumes, and increased microglial activation. Transcriptomic analysis identified age- and TBI-specific gene changes consistent with a disease-associated microglial signature in the chronically injured brain, including those involved with complement, phagocytosis, and autophagy pathways. Dysregulation of phagocytic and autophagic function in microglia was accompanied by increased neuroinflammation in old mice. As proof-of-principle that these pathways have functional importance, we administered an autophagic enhancer, trehalose, in drinking water continuously for 8 weeks after TBI. Old mice treated with trehalose showed enhanced functional recovery and reduced microglial activation late after TBI compared to the sucrose control group. Our data indicate that microglia undergo chronic changes in autophagic regulation with both normal aging and TBI that are associated with poorer functional outcome. Enhancing autophagy may therefore be a promising clinical therapeutic strategy for TBI, especially in older patients.

Trehalose Reduces Nerve Injury Induced Nociception in Mice but Negatively Affects Alertness

Trehalose, a sugar from fungi, mimics starvation due to a block of glucose transport and induces Transcription Factor EB- mediated autophagy, likely supported by the upregulation of progranulin. The pro-autophagy effects help to remove pathological proteins and thereby prevent neurodegenerative diseases such as Alzheimer’s disease. Enhancing autophagy also contributes to the resolution of neuropathic pain in mice. Therefore, we here assessed the effects of continuous trehalose administration via drinking water using the mouse Spared Nerve Injury model of neuropathic pain. Trehalose had no effect on drinking, feeding, voluntary wheel running, motor coordination, locomotion, and open field, elevated plus maze, and Barnes Maze behavior, showing that it was well tolerated. However, trehalose reduced nerve injury-evoked nociceptive mechanical and thermal hypersensitivity as compared to vehicle. Trehalose had no effect on calcium currents in primary somatosensory neurons, pointing to central mechanisms of the antinociceptive effects. In IntelliCages, trehalose-treated mice showed reduced activity, in particular, a low frequency of nosepokes, which was associated with a reduced proportion of correct trials and flat learning curves in place preference learning tasks. Mice failed to switch corner preferences and stuck to spontaneously preferred corners. The behavior in IntelliCages is suggestive of sedative effects as a “side effect” of a continuous protracted trehalose treatment, leading to impairment of learning flexibility. Hence, trehalose diet supplements might reduce chronic pain but likely at the expense of alertness.

Mitophagy pathways and Alzheimer's disease: From pathogenesis to treatment

Alzheimer's disease (AD) is an age-dependent, incurable mental illness that is associated with the accumulation of aggregates of amyloid-beta (Aβ) and hyperphosphorylated tau fragments (p-tau). Detailed studies on postmortem AD brains, cell lines, and mouse models of AD have shown that numerous cellular alterations, including mitochondrial deficits, synaptic disruption and glial/astrocytic activation, are involved in the disease process. Mitophagy is a cellular process by which damaged/weakened mitochondria are selectively eliminated from the cell. In AD, impairments in mitophagy trigger the gradual accumulation of defective mitochondria. This review will focus on the recent progress in understanding the molecular mechanisms and pathological role of mitophagy and its implications for AD pathogenesis. We will also discuss the novel concept of the regulation of mitophagy as a therapeutic avenue for the prevention and treatment of AD.

miR-146a aggravates cognitive impairment and Alzheimer disease-like pathology by triggering oxidative stress through MAPK signaling

INTRODUCTION

Mir-146a-5p has been widely recognized as a critical regulatory element in the immune response. However, recent studies have shown that miR-146a-5p may also be involved in the development of Alzheimer disease (AD). Regrettably, the related mechanisms are poorly understood. Here, we investigated the effects of miR-146a in mice models and SH-SY5Y cells treated with amyloid β (Aβ)1-42.

METHODS

To create a model of AD, SH-SY5Y cells were treated with Aβ1-42 and mice received intracerebroventricular injections of Aβ1-42. Then, the transcriptional levels of miR-146a were estimated by real-time PCR. We transiently transfected the miR-146a-5p mimic/inhibitor into cells and mice to study the role of miR-146a. The role of signaling pathways including p38 and reactive oxygen species (ROS) was studied by using specific inhibitors. Aβ and amyloid-beta precursor protein (APP)levels were measured by immunoblotting. Furthermore, Aβ expression was analyzed by immunofluorescence and histochemical examinations.

RESULTS

Aβ1-42-stimulated SH-SY5Y cells displayed increased transcriptional levels of miR-146a and APP. Moreover, the p38 MAPK signaling pathway and ROS production were activated upon stimulation with a miR-146a-5p mimic. However, treatment with a miR-146a-5p inhibitor decreased the levels of APP, ROS, and p-p38 MAPK. A similar phenomenon was also observed in the animals treated with Aβ1-42, in which miR-146a upregulation increased the expression of Aβ, p-p38, and ROS, while the inhibition of miR-146a had the opposite effect. This suggests that miR-146a increases Aβ deposition and ROS accumulation via the p-p38 signaling pathway.

CONCLUSIONS

Our research demonstrates that miR-146a-5pa increases Aβ deposition by triggering oxidative stress through activation of MAPK signaling.

The interplay between lipid and Aβ amyloid homeostasis in Alzheimer's Disease: risk factors and therapeutic opportunities

Alzheimer's Diseases (AD) is characterized by the accumulation of amyloid deposits of Aβ peptide in the brain. Besides genetic background, the presence of other diseases and an unhealthy lifestyle are known risk factors for AD development. Albeit accumulating clinical evidence suggests that an impaired lipid metabolism is related to Aβ deposition, mechanistic insights on the link between amyloid fibril formation/clearance and aberrant lipid interactions are still unavailable. Recently, many studies have described the key role played by membrane bound Aβ assemblies in neurotoxicity. Moreover, it has been suggested that a derangement of the ubiquitin proteasome pathway and autophagy is significantly correlated with toxic Aβ aggregation and dysregulation of lipid levels. Thus, studies focusing on the role played by lipids in Aβ aggregation and proteostasis could represent a promising area of investigation for the design of valuable treatments. In this review we examine current knowledge concerning the effects of lipids in Aβ aggregation and degradation processes, focusing on the therapeutic opportunities that a comprehensive understanding of all biophysical, biochemical, and biological processes involved may disclose.