The role of inflammation and endoplasmic reticulum stress in obesity-related cognitive impairment

MTCH2 Suppresses Thermogenesis by Regulating Autophagy in Adipose Tissue

Stimulating adipose tissue thermogenesis has emerged as a promising strategy for combating obesity, with uncoupling protein 1 (UCP1) playing a central role in this process. However, the mechanisms that suppress adipose thermogenesis and energy dissipation in obesity are not fully understood. This study identifies mitochondrial carrier homolog 2 (MTCH2), an obesity susceptibility gene, as a negative regulator of energy homeostasis across flies, rodents, and humans. Notably, adipose-specific MTCH2 depletion in mice protects against high-fat-diet (HFD)-induced obesity and metabolic disorders. Mechanistically, MTCH2 deficiency promotes energy expenditure by stimulating thermogenesis in brown adipose tissue (BAT) and browning of subcutaneous white adipose tissue (scWAT), accompanied by upregulated UCP1 protein expression, enhanced mitochondrial biogenesis, and increased lipolysis in BAT and scWAT. Using integrated RNA sequencing and proteomic analyses, this study demonstrates that MTCH2 is a key suppressor of thermogenesis by negatively regulating autophagy via Bcl-2-dependent mechanism. These findings highlight MTCH2's critical role in energy homeostasis and reveal a previously unrecognized link between MTCH2, thermogenesis, and autophagy in adipose tissue biology, positioning MTCH2 as a promising therapeutic target for obesity and related metabolic disorders. This study provides new opportunities to develop treatments that enhance energy expenditure.

Astrocyte involvement in metabolic regulation and disease

Astrocytes, the predominant glial cell type in the mammalian brain, influence a wide variety of brain parameters including neuronal energy metabolism. Exciting recent studies have shown that obesity and diabetes can impact on astrocyte function. We review evidence that dysregulation of astrocytic lipid metabolism and glucose sensing contributes to dysregulation of whole-body energy balance, thermoregulation, and insulin sensitivity. In addition, we consider the overlooked topic of the sex-specific roles of astrocytes and their response to hormonal fluctuations that provide insights into sex differences in metabolic regulation. Finally, we provide an update on potential ways to manipulate astrocyte function, including genetic targeting, optogenetic and chemogenetic techniques, transplantation, and tailored exosome-based therapies, which may lead to improved treatments for metabolic disease.

Okra seed polysaccharides mitigate neuroinflammation and cognitive impairment via modulation of Nrf2/HO-1, HMGB1/RAGE/TLR4/NF-κB, NLRP3/Caspase-1, JAK-2/STAT-3, AMPK/SIRT1/m-TOR, PI3K/AKT/CREB/BDNF/TrkB and PERK/CHOP/Bcl-2 axes

Global healthcare systems are under tremendous strain due to the increasing prevalence of neurodegenerative disorders. Growing data suggested that overconsumption of high-fat/high-carbohydrates diet (HFHCD) is associated with enhanced incidence of metabolic alterations, neurodegeneration, and cognitive dysfunction. Functional foods have gained prominence in curbing metabolic and neurological deficits. Consequently, this study endeavored to explore effects of purified Okra seed polysaccharides (OP) (Abelmoschus esculentus (L.) Moench) against HFHCD-induced metabolic alterations and cognitive dysfunction, with elucidating underlying contributed mechanistic pathways. OP hydrolysate was analyzed using GC-MS analysis. The biological study encompassed two phases, the first phase I (model establishment phase), for 3 months, involved a control group, fed standard diet, and HFHCD group. The second phase (phase II) where HFHCD fed rats were re-divided into 3 equal subgroups, 1st subgroup received HFHCD, whereas second and third subgroups received OP, 200 or 400 mg/kg/day, respectively, for 28 days. GC-MS characterized OP as an arabinogalactouranan and revealed the monosaccharide composition as galacturonic acid: arabinose: glucose: galactose: rhamnose: xylose in ratio of 28.2: 23.3: 11.5: 4.2: 3.5: 2.0. The findings demonstrated that OP dose-dependently mitigated HFHCD-induced rise in body weights, lipid profiles, levels of blood glucose and disruption in behavioral outcomes, neurotransmitters, together with histopathological alterations in brain. Moreover, OP dose-dependently improved redox, neuroinflammatory, endoplasmic reticulum (ER) stress, autophagic and apoptotic biomarkers. OP can be regarded as promising functional food candidate to hamper HFHCD-induced metabolic alterations and cognitive deficit, via enhancing Nrf2/HO-1, AMPK/SIRT1 and PI3K/AKT/CREB axes, long with dampening of HMGB1/RAGE/TLR4, NLRP3/Caspase-1, JAK-2/STAT-3 and PERK/CHOP axes.

The clinical features and potential mechanisms of cognitive disorders in peripheral autoimmune and inflammatory diseases

According to a study from World Health Organization's Global Burden of Disease, mental and neurological disorders have accounted for 13% of global diseases in recent years and are on the rise. Neuropsychiatric conditions or neuroinflammatory disorders are linked by the presence of an exaggerated immune response both peripherally and in the central nervous system (CNS). Cognitive dysfunction (CD) encompasses a complex group of diseases and has frequently been described in the field of autoimmune diseases, especially in multiple non-CNS-related autoimmune diseases. Recent studies have provided various hypotheses regarding the occurrence of cognitive impairment in autoimmune diseases, including that abnormally activated immune cells can disrupt the integrity of the blood-brain barrier (BBB) to trigger a central neuroinflammatory response. When the BBB is intact, autoantibodies and pro-inflammatory molecules in peripheral circulation can enter the brain to activate microglia, inducing CNS inflammation and CD. However, the mechanisms explaining the association between the immune system and neural function and their contribution to diseases are uncertain. In this review, we used clinical statistics to illustrate the correlation between CD and autoimmune diseases that do not directly affect the CNS, summarized the clinical features and mechanisms by which autoimmune diseases trigger cognitive impairment, and explored existing knowledge regarding the link between CD and autoimmune diseases from the perspective of the field of neuroimmunology.

An investigation of the endoplasmic reticulum stress in obesity exposure in the prenatal period

OBJECTIVES

Exposure to maternal obesity has been shown to make offspring more prone to cognitive and metabolic disorders later in life. Although the underlying mechanisms are unclear, the role of endoplasmic reticulum (ER) stress in the fetal programming process is remarkable. ER stress can be activated by many chronic diseases, including obesity and diabetes. Therefore, our study aimed to investigate the role of ER stress caused by maternal diet-induced obesity in the offspring hippocampus. We also evaluated the protective effect of N-acetylcysteine (NAC) against ER stress.

METHODS

A rat obesity model was created by providing a high-fat (60 % kcal) diet. N-acetylcysteine (NAC) was administered at a dosage of 150 mg/kg via the intragastric route. The animals were mated at the age of 12 weeks. The same diet was maintained during pregnancy and lactation. The experiment was terminated on the postnatal 28th day, and the offspring's brain tissues were examined. Immunohistochemical staining for ER stress markers was performed on sections taken from tissues after routine histological procedures.

RESULTS

The results revealed increased GRP78, PERK, and eIF2α immunoreactivities in the hippocampal dentate gyrus (DG) and cornu ammonis 1 (CA1) regions in the obese group offspring, while the expression of those markers in those regions normalized with NAC supplementation (p < 0.01). Statistical analysis of XBP1 immunoreactivity H-scores revealed no difference between the study groups (p > 0.05).

DISCUSSION

These results suggest that exposure to obesity during the prenatal period may cause increased ER stress in hippocampal neurons, which have an important role in the regulation of learning, memory and behavior, and this may contribute to decreased cognitive performance. On the other hand, NAC stands out as an effective agent that can counteract hippocampal ER stress.

DeepGAMI: deep biologically guided auxiliary learning for multimodal integration and imputation to improve genotype-phenotype prediction

BACKGROUND

Genotypes are strongly associated with disease phenotypes, particularly in brain disorders. However, the molecular and cellular mechanisms behind this association remain elusive. With emerging multimodal data for these mechanisms, machine learning methods can be applied for phenotype prediction at different scales, but due to the black-box nature of machine learning, integrating these modalities and interpreting biological mechanisms can be challenging. Additionally, the partial availability of these multimodal data presents a challenge in developing these predictive models.

METHOD

To address these challenges, we developed DeepGAMI, an interpretable neural network model to improve genotype-phenotype prediction from multimodal data. DeepGAMI leverages functional genomic information, such as eQTLs and gene regulation, to guide neural network connections. Additionally, it includes an auxiliary learning layer for cross-modal imputation allowing the imputation of latent features of missing modalities and thus predicting phenotypes from a single modality. Finally, DeepGAMI uses integrated gradient to prioritize multimodal features for various phenotypes.

RESULTS

We applied DeepGAMI to several multimodal datasets including genotype and bulk and cell-type gene expression data in brain diseases, and gene expression and electrophysiology data of mouse neuronal cells. Using cross-validation and independent validation, DeepGAMI outperformed existing methods for classifying disease types, and cellular and clinical phenotypes, even using single modalities (e.g., AUC score of 0.79 for Schizophrenia and 0.73 for cognitive impairment in Alzheimer's disease).

CONCLUSION

We demonstrated that DeepGAMI improves phenotype prediction and prioritizes phenotypic features and networks in multiple multimodal datasets in complex brains and brain diseases. Also, it prioritized disease-associated variants, genes, and regulatory networks linked to different phenotypes, providing novel insights into the interpretation of gene regulatory mechanisms. DeepGAMI is open-source and available for general use.

Effect of Heat Stress on Hippocampal Neurogenesis: Insights into the Cellular and Molecular Basis of Neuroinflammation-Induced Deficits

Heat stress is known to result in neuroinflammation, neuronal damage, and disabilities in learning and memory in animals and humans. It has previously been reported that cognitive impairment caused by neuroinflammation may at least in part be mediated by defective hippocampal neurogenesis, and defective neurogenesis has been linked to aberrantly activated microglial cells. Moreover, the release of cytokines within the brain has been shown to contribute to the disruption of cognitive functions in several conditions following neuroinflammation. In this review, we summarize evolving evidence for the current understanding of inflammation-induced deficits in hippocampal neurogenesis, and the resulting behavioral impairments after heat stress. Furthermore, we provide valuable insights into the molecular and cellular mechanisms underlying neuroinflammation-induced deficits in hippocampal neurogenesis, particularly relating to cognitive dysfunction following heat stress. Lastly, we aim to identify potential mechanisms through which neuroinflammation induces cognitive dysfunction, and elucidate how neuroinflammation contributes to defective hippocampal neurogenesis. This review may therefore help to better understand the relationship between hippocampal neurogenesis and heat stress.

A HBDI-Based Fluorescent Probe for Labeling Endoplasmic Reticulum in Living Cells

The endoplasmic reticulum (ER) is an important organelle in eukaryotic cells and is closely involved in the synthesis and processing of proteins, as well as the storage, regulation, and release of calcium. A series of signaling pathways within the ER play a crucial part in the pathogenesis of various diseases, including cancer. Thus, it is necessary to design ER-targeting probes to monitor these signaling pathways. Additionally, precision medicine also requires new ER-targeting group to facilitate the delivery of drug cargoes to the ER. However, only a limited number of ER-targeting groups have been used for the design of fluorescent probes for ER imaging in living cells, as well as the development of ER-targeted drug delivery systems. Herein, a new ER-targeting fluorescent probe (BDI-ER) was designed and prepared. BDI-ER contains the hydrophilic fluorophore, derived from the core structure of GFP, and two hydrophobic octadecane chains. The amphipathic nature of BDI-ER facilitates localization in the ER. Live cell imaging demonstrated selective localization of BDI-ER towards ER compared to other organelles. Additionally, co-localization imaging in various cell lines indicate that BDI-ER is effective at targeting the ER.

Lipotoxicity suppresses the synthesis of growth hormone in pituitary somatotrophs via endoplasmic reticulum stress

Lipotoxicity has been shown to cause dysfunction of many organs and tissues. However, it is unclear whether lipotoxicity is harmful to the somatotrophs, a kind of cell that synthesize growth hormone (GH) in the pituitary. In this study, we performed an epidemiological study, serum levels of triglyceride (TG) and GH showed a negative correlation, even after adjustment for potential confounders. In an animal study, male Sprague‐Dawley rats were fed a high‐fat diet (HFD) or a control diet for 28 weeks. HFD rats showed impaired GH synthesis, resulting in a decrease in circulating GH levels. The expression of pituitary Pit‐1, a key transcription factor of GH, was inhibited. We found that the inositol‐requiring enzyme 1α (IRE1α) pathway of endoplasmic reticulum (ER) stress was triggered in HFD rat pituitary glands and palmitic acid‐treated GH3 cells, respectively. On the contrary, applying 4‐phenyl butyric acid (4‐PBA) to alleviate ER stress or 4µ8c to specifically block the IRE1α pathway attenuated the impairment of both Pit‐1 and GH expression. In conclusion, we demonstrated that lipotoxicity directly inhibits the synthesis of GH, probably by reducing Pit‐1 expression. The IRE1α signaling pathway of ER stress may play an important role in this process.

Updated Role of Neuropeptide Y in Nicotine-Induced Endothelial Dysfunction and Atherosclerosis

Cardiovascular disease is the leading cause of death worldwide. Endothelial dysfunction of the arterial vasculature plays a pivotal role in cardiovascular pathogenesis. Nicotine-induced endothelial dysfunction substantially contributes to the development of arteriosclerotic cardiovascular disease. Nicotine promotes oxidative inflammation, thrombosis, pathological angiogenesis, and vasoconstriction, and induces insulin resistance. However, the exact mechanism through which nicotine induces endothelial dysfunction remains unclear. Neuropeptide Y (NPY) is widely distributed in the central nervous system and peripheral tissues, and it participates in the pathogenesis of atherosclerosis by regulating vasoconstriction, energy metabolism, local plaque inflammatory response, activation and aggregation of platelets, and stress and anxiety-related emotion. Nicotine can increase the expression of NPY, suggesting that NPY is involved in nicotine-induced endothelial dysfunction. Herein, we present an updated review of the possible mechanisms of nicotine-induced atherosclerosis, with a focus on endothelial cell dysfunction associated with nicotine and NPY.

The Role of Hypothalamic Inflammation in Diet-Induced Obesity and Its Association with Cognitive and Mood Disorders

Obesity is often associated with cognitive and mood disorders. Recent evidence suggests that obesity may cause hypothalamic inflammation. Our aim was to investigate the hypothesis that there is a causal link between obesity-induced hypothalamic inflammation and cognitive and mood disorders. Inflammation may influence hypothalamic inter-connections with regions important for cognition and mood, while it may cause dysregulation of the Hypothalamic-Pituitary-Adrenal (HPA) axis and influence monoaminergic systems. Exercise, healthy diet, and glucagon-like peptide receptor agonists, which can reduce hypothalamic inflammation in obese models, could improve the deleterious effects on cognition and mood.

Dysbiosis is one of the risk factor for stroke and cognitive impairment and potential target for treatment

More than 50 million people have various forms of cognitive impairment basically caused by neurodegenerative diseases, such as Alzheimer's, Parkinson's, and cerebrovascular diseases as well as stroke. Often these conditions coexist and exacerbate one another. The damaged area in post-stroke dementia may lead to neurodegenerative lesions. Gut microbiome functions like an endocrine organ by generating bioactive metabolites that can directly or indirectly impact human physiology. An alteration in the composition and function of intestinal flora, i.e. gut dysbiosis, is implicated in neurodegenerative and cerebrovascular diseases. Additionally, gut dysbiosis may accelerate the progression of cognitive impairment. Dysbiosis may result from obesity; metabolic disorders, cardiovascular disease, and sleep disorders, Lack of physical activity is associated with dysbiosis as well. These may coexist in various patterns in older people, enhancing the risk, incidence, and progression of cerebrovascular lesions, neurodegenerative disorders, and cognitive impairment, creating a vicious circle. Recently, it has been reported that several metabolites produced by gut microbiota (e.g., trimethylamine/trimethylamine N-oxide, short-chain fatty acids, secondary bile acids) may be linked to neurodegenerative and cerebrovascular diseases. New treatment modalities, including prebiotic and probiotics, may normalize the gut microbiota composition, change the brain-gut barrier, and decrease the risk of the pathology development. Fecal microbiota transplantation, sometimes in combination with other methods, is used for remodeling and replenishing the symbiotic gut microbiome. This promising field of research is associated with basic findings of bidirectional communication between body organs and gut microbiota that creates new possibilities of pharmacological treatments of many clinical conditions. The authors present the role of gut microbiota in physiology, and the novel therapeutic targets in modulation of intestinal microbiota Personalized therapies based on their personal genome make up could offer benefits by modulating microbiota cross-talk with brain and cardiovascular system. A healthy lifestyle, including pre and probiotic nutrition is generally recommended. Prevention may also be enhanced by correcting gut dysbiosis resulting a reduced risk of post-stroke cognitive impairment including dementia.

Neural Underpinnings of Obesity: The Role of Oxidative Stress and Inflammation in the Brain

Obesity prevalence is increasing at an unprecedented rate throughout the world, and is a strong risk factor for metabolic, cardiovascular, and neurological/neurodegenerative disorders. While low-grade systemic inflammation triggered primarily by adipose tissue dysfunction is closely linked to obesity, inflammation is also observed in the brain or the central nervous system (CNS). Considering that the hypothalamus, a classical homeostatic center, and other higher cortical areas (e.g. prefrontal cortex, dorsal striatum, hippocampus, etc.) also actively participate in regulating energy homeostasis by engaging in inhibitory control, reward calculation, and memory retrieval, understanding the role of CNS oxidative stress and inflammation in obesity and their underlying mechanisms would greatly help develop novel therapeutic interventions to correct obesity and related comorbidities. Here we review accumulating evidence for the association between ER stress and mitochondrial dysfunction, the main culprits responsible for oxidative stress and inflammation in various brain regions, and energy imbalance that leads to the development of obesity. Potential beneficial effects of natural antioxidant and anti-inflammatory compounds on CNS health and obesity are also discussed.

In silico toxicity evaluation of Salubrinal and its analogues

This paper reports on a comprehensive in silico toxicity assessment of Salubrinal and its analogues containing a cinnamic acid residue or quinoline ring using the online servers admetSAR, ADMETlab, ProTox, ADVERPred, Pred-hERG and Vienna LiverTox. Apart from rare exceptions, in all 55 studied structures, mild or practical absence of acute toxicity was predicted for rats (III or IV toxicity class). Cardiotoxic, hepatotoxic and immunotoxic effects were predicted for Salubrinal and its analogues. We constructed models of the main predicted anti-targets hERG, BSEP, MRP3, MRP4 and AhR using the principle of homologous modeling. Molecular docking studies were carried out with the obtained models. We carried out molecular docking for all targets using AutoDock Vina, implemented in the PyRx 0.8 software package. According to the results of molecular docking, the compounds analyzed are potential moderate or weak hERG blockers. Induction of cholestasis and, as a consequence, liver damage by these drugs, directly related to inhibition of BSEP, MRP3 and MRP4, most likely will not be observed. Interaction with AhR for the studied compounds is impossible for steric reasons and, as a consequence, toxic effects on the immune and other organ systems associated with the activation of the AhR signaling pathway are excluded.

Association Between Lipid Accumulation Product and Mild Cognitive Impairment in Patients with Type 2 Diabetes

BACKGROUND

Diabetes may increase the risk of conversion of mild cognitive impairment (MCI) to dementia. Lipid accumulation product (LAP), an index of visceral obesity, has been shown to be a powerful predictor of insulin resistance and type 2 diabetes (T2D). However, little attention has been paid to the relationship between LAP and MCI in T2D.

OBJECTIVE

We aimed to investigate the association between the LAP index and MCI in patients with T2D.

METHODS

In total, 220 hospitalized patients with T2D, including 113 MCI patients and 107 patients with normal cognition, were enrolled in this cross-sectional study. We collected demographic, anthropometric, and biochemical data on each subject. The LAP index was calculated according to the following formulas: [waist circumference (WC) (cm) - 65]×triglyceride (TG) (mmol/L) for males and [WC (cm) - 58] ×TG (mmol/L) for females.

RESULTS

Compared with patients with normal cognition, MCI patients were older and had a higher LAP index, WC, body mass index, and glycosylated hemoglobin A1c level, as well as a lower Montreal Cognitive Assessment score and education level (p < 0.05). After adjusting for confounding factors, LAP index was associated with MCI (OR = 1.047, 95% CI = 1.031-1.063, p < 0.01). The area under the ROC curve (AUC) for the LAP index was higher than that for WC and BMI.

CONCLUSION

A high LAP index is associated with an increased risk of MCI in T2D patients. The LAP index appears to be a good indicator of risk of MCI in patients with T2D.