Glutamine Improves Oxidative Stress through the Wnt3a/β-Catenin Signaling Pathway in Alzheimer's Disease In Vitro and In Vivo

Glutamine Promotes Porcine Intestinal Epithelial Cell Proliferation through the Wnt/β-Catenin Pathway

Glutamine (Gln) is a critical nutrient required by neonatal mammals for intestinal growth, especially for newborn piglets. However, the mechanisms underlying the role of Gln in porcine intestinal epithelium development are not fully understood. The objective of the current study was to explore the possible signaling pathway involved in the promotion of porcine intestinal epithelial cell (IPEC-J2) proliferation by Gln. The results showed that 1 mM Gln promoted IPEC-J2 cell proliferation, and tandem mass tag proteomics revealed 973 differentially expressed proteins in Gln-treated IPEC-J2 cells, 824 of which were upregulated and 149 of which were downregulated. Moreover, gene set enrichment analysis indicated that the Wnt signaling pathway is activated by Gln treatment. Western blotting analysis further confirmed that Gln activated the Wnt/β-catenin signaling pathway. In addition, Gln increased not only cytosolic β-catenin but also nuclear β-catenin protein expression. LF3 (a β-catenin/TCF4 interaction inhibitor) assay and β-catenin knockdown demonstrated that Gln-mediated promotion of Wnt/β-catenin signaling and cell proliferation were blocked. Furthermore, the inhibition of TCF4 expression suppressed Gln-induced cell proliferation. These findings further confirmed that Wnt/β-catenin signaling is involved in the promotion of IPEC-J2 cell proliferation by Gln. Collectively, these findings demonstrated that Gln positively regulated IPEC-J2 cell proliferation through the Wnt/β-catenin pathway. These data greatly enhance the current understanding of the mechanism by which Gln regulates intestinal development.

Gut microbiota in combination with blood metabolites reveals characteristics of the disease cluster of coronary artery disease and cognitive impairment: a Mendelian randomization study

Background

The coexistence of coronary artery disease (CAD) and cognitive impairment has become a common clinical phenomenon. However, there is currently limited research on the etiology of this disease cluster, discovery of biomarkers, and identification of precise intervention targets.

Methods

We explored the causal connections between gut microbiota, blood metabolites, and the disease cluster of CAD combined with cognitive impairment through two-sample Mendelian randomization (TSMR). Additionally, we determine the gut microbiota and blood metabolites with the strongest causal associations using Bayesian model averaging multivariate Mendelian randomization (MR-BMA) analysis. Furthermore, we will investigate the mediating role of blood metabolites through a two-step Mendelian randomization design.

Results

We identified gut microbiota that had significant causal associations with cognitive impairment. Additionally, we also discovered blood metabolites that exhibited significant causal associations with both CAD and cognitive impairment. According to the MR-BMA results, the free cholesterol to total lipids ratio in large very low density lipoprotein (VLDL) was identified as the key blood metabolite significantly associated with CAD. Similarly, the cholesteryl esters to total lipids ratio in small VLDL emerged as the primary blood metabolite with a significant causal association with dementia with lewy bodies (DLB). For the two-step Mendelian randomization analysis, we identified blood metabolites that could potentially mediate the association between genus Butyricicoccus and CAD in the potential causal links.

Conclusion

Our study utilized Mendelian randomization (MR) to identify the gut microbiota features and blood metabolites characteristics associated with the disease cluster of CAD combined with cognitive impairment. These findings will provide a meaningful reference for the identification of biomarkers for the disease cluster of CAD combined with cognitive impairment as well as the discovery of targets for intervention to address the problems in the clinic.

The essential role of glutamine metabolism in diabetic cardiomyopathy: A review

Diabetic cardiomyopathy (DCM) is a pathophysiological condition caused by diabetes mellitus and is the leading cause of diabetes mellitus-related mortality. The pathophysiology of DCM involves various processes, such as oxidative stress, inflammation, ferroptosis, and abnormal protein modification. New evidence indicates that dysfunction of glutamine (Gln) metabolism contributes to the pathogenesis of DCM by regulating these pathophysiological mechanisms. Gln is a conditionally essential amino acid in the human body, playing a vital role in maintaining cell function. Although the precise molecular mechanisms of Gln in DCM have yet to be fully elucidated, recent studies have shown that supplementing with Gln improves cardiac function in diabetic hearts. However, excessive Gln may worsen myocardial injury in DCM by generating a large amount of glutamates or increasing O-GlcNacylation. To highlight the potential therapeutic method targeting Gln metabolism and its downstream pathophysiological mechanisms, this article aims to review the regulatory function of Gln in the pathophysiological mechanisms of DCM.

Glutamine inhibits inflammation, oxidative stress, and apoptosis and ameliorates hyperoxic lung injury

Glutamine (Gln) is the most widely acting and abundant amino acid in the body and has anti-inflammatory properties, regulates body metabolism, and improves immune function. However, the mechanism of Gln's effect on hyperoxic lung injury in neonatal rats is unclear. Therefore, this work focused on examining Gln's function in lung injury of newborn rats mediated by hyperoxia and the underlying mechanism. We examined body mass and ratio of wet-to-dry lung tissue weights of neonatal rats. Hematoxylin and eosin (HE) staining was performed to examine histopathological alterations of lung tissues. In addition, enzyme-linked immunoassay (ELISA) was conducted to measure pro-inflammatory cytokine levels within bronchoalveolar lavage fluid (BALF). Apoptosis of lung tissues was observed using TUNEL assay. Western blotting was performed for detecting endoplasmic reticulum stress (ERS)-associated protein levels. The results showed that Gln promoted body weight gain, significantly reduced pathological damage and oxidative stress in lung tissue, and improved lung function in neonatal rats. Gln reduced pro-inflammatory cytokine release as well as inflammatory cell production in BALF and inhibited apoptosis in lung tissue cells. Furthermore, we found that Gln could downregulate ERS-associated protein levels (GRP78, Caspase-12, CHOP) and inhibit c-Jun N-terminal kinase (JNK) and inositol-requiring enzyme 1 alpha (IRE1α) phosphorylation. These results in an animal model of bronchopulmonary dysplasia (BPD) suggest that Gln may have a therapeutic effect on BPD by reducing lung inflammation, oxidative stress, and apoptosis and improving lung function; its mechanism of action may be related to the inhibition of the IRE1α/JNK pathway.

Momordica charantia polysaccharide ameliorates D-galactose-induced aging through the Nrf2/β-Catenin signaling pathway

Aging is widely thought to be associated with oxidative stress. Momordica charantia (MC) is a classic vegetable and traditional herbal medicine widely consumed in Asia, and M. charantia polysaccharide (MCP) is the main bioactive ingredient of MC. We previously reported an antioxidative and neuroprotective effect of MCP in models of cerebral ischemia/reperfusion and hemorrhage injury. However, the role played by MCP in neurodegenerative diseases, especially during aging, remains unknown. In this study, we investigated the protective effect of MCP against oxidative stress and brain damage in a D-galactose-induced aging model (DGAM). The Morris water maze test was performed to evaluate the spatial memory function of model rats. The levels of malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were measured and telomerase activity was determined. The results showed that MCP treatment attenuated spatial memory dysfunction induced by D-galactose. In addition, MCP increased antioxidant capacity by decreasing MDA and increasing SOD and GSH levels. MCP treatment also improved telomerase activity in aging rats. Mechanistically, MCP promoted the entry of both Nrf2 and β-Catenin into the nucleus, which is the hallmark of antioxidation signaling pathway activation. This study highlights a role played by MCP in ameliorating aging-induced oxidative stress injury and reversing the decline in learning and memory capacity. Our work provides evidence that MCP administration might be a potential antiaging strategy.

Boswellic acids ameliorate neurodegeneration induced by AlCl3: the implication of Wnt/β-catenin pathway

Alzheimer's disease (AD) is a neurodegenerative disease (ND) that represents the principal cause of dementia. Effective treatment is still lacking. Without prevention, Alzheimer's disease (AD) incidence is expected to triple within 30 years. The risk increases in highly polluted areas and is positively linked to chronic aluminum (Al) exposure. Canonical Wingless-Int (Wnt)/β-catenin pathway has been found to play a considerable role in ND pathogenesis. Resins of Boswellia serrata (frankincense) have been used traditionally for their psychoactive activity, in addition to their memory-boosting effects. Boswellic acids (BA) are pentacyclic triterpenes. They have antioxidant, anti-inflammatory, antinociceptive, and immunomodulatory activities. This study aimed to elucidate the role of the Wnt/β-catenin pathway in BA protective activity against aluminum-induced Alzheimer's disease. For 6 weeks, rats were treated daily with AlCl3 (100 mg/kg/i.p.) either alone or with BA (125 or 250 mg/kg PO). Results indicated that BA significantly improved learning and memory impairments induced by AlCl3 treatment. Moreover, BA treatment significantly decreased acetylcholinesterase levels and reduced amyloid-beta (Aβ) expression. In addition, BA ameliorated the increased expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), inhibited lipid peroxidation, and increased total antioxidants in the brain. Indeed, BA significantly suppressed AlCl3-induced decrease of brain-derived neurotrophic factor, pGSK-3β (Ser 9), and β-catenin. BA (250 mg/kg) showed a significant protective effect compared to a lower dose. The results conclude that BA administration modulated the expression of Wnt/β-catenin pathway-related parameters, contributing to BA's role against Al-induced Alzheimer's disease. Effect of Boswellic acids on AlCl3-induced neurodegenerative changes. ChE cholinesterase, Ach acetylcholine, BDNF brain-derived neurotrophic factor, IL-1β interleukin-1β, TNF-α tumor necrosis factor-α.

Low-dose exposure to phytosynthesized gold nanoparticles combined with glutamine deprivation enhances cell death in the cancer cell line HeLa via oxidative stress-mediated mitochondrial dysfunction and G0/G1 cell cycle arrest

Cancer cells use nutrients like D-glucose (Glc) and L-glutamine (Q) more efficiently for their development. This increased nutritional dependency of malignant cells has been commonly employed in various in vitro and in vivo models of anticancer therapies. This study utilized a combination of a low dose (25 μg mL^-1) of S2, a phytosynthesized gold nanoparticle (AuNP) that was previously proven to be non-toxic, and deprivation of extracellular glutamine as an anticancer strategy in the human cervical cancer cell line HeLa. We discovered that 24 h Q deprivation led to a less significant decrease in the viability of HeLa cells while a low dose of S2 caused a non-significant reduction in the viability of HeLa cells. However, combining these two treatments resulted in highly significant inhibition of cell growth, as measured by the MTT test and morphological examination. Glutamine starvation in HeLa cells was found to induce cellular uptake of S2 via clathrin-mediated endocytosis, thus facilitating the improved antitumor effects of the combined treatment. Flow cytometry-based assays using fluorescent probes H₂DCFDA and MitoSOX Red confirmed that this combination therapy involved the development of oxidative stress conditions owing to a surplus of cytosolic reactive oxygen species (cytoROS) and mitochondrial superoxide (mtSOX) generation. Furthermore, the investigated combinatorial treatment also indicated mitochondrial inactivity and disintegration, as evidenced by the drop in the mitochondrial membrane potential (Δψ_m) and the decrease in the mitochondrial mass (mtMass) in a flow-cytometric assay utilizing the probes. Tetramethylrhodamine ethyl ester and MitoTracker Green FM, respectively. Cell cycle arrest in the G0/G1 phase, induction of cell death via apoptosis/necrosis, and inhibition of migration capacities of HeLa cells were also seen after the combined treatment. Thus, this research provides insight into a new combinatorial approach for reducing the dose of nanoparticles and increasing their efficacy to better inhibit the growth of human cervical cancer cells by leveraging their extracellular glutamine dependence.

Ginkgolide B inactivates the NLRP3 inflammasome by promoting autophagic degradation to improve learning and memory impairment in Alzheimer's disease

The NLR family, pyrin domain containing 3 (NLRP3) inflammasome drives the progression of Alzheimer's disease (AD). Ginkgolide B (GB) is a potential anti-inflammatory compound that controls neuro-inflammation. The aim of this study was to evaluate the effect of GB on the NLRP3 inflammasome in AD. The effect of GB on the conversion between the M1 and M2 microglial phenotype was examined using quantitative real-time PCR and immunostaining. Western blotting assays and ELISA were used to detect changes in neuro-inflammation following GB treatment, including the NLRP3 inflammasome pathway and autophagy. In order to evaluate the cognitive function of male senescence-accelerated mouse prone 8 (SAMP8) mice, behavioral tests, including the Morris water maze and novel object recognition tests, were performed. GB significantly decreased the intracellular pro-inflammatory cytokine levels in lipopolysaccharide-treated BV2 cells and improved cognitive behavior in SAMP8 mice. Moreover, GB deactivated the NLRP3 inflammasome, and this effect was dependent on autophagy. Ubiquitination was associated with GB-induced autophagic NLRP3 degradation. These results were further validated in the hippocampus of SAMP8 mice. Thus, GB exerted a neuroprotective effect on the cognitive function of SAMP8 mice by suppressing the activation of NLRP3 inflammasome via autophagic degradation.

Down-regulation of microRNA-342-5p or Up-regulation of Wnt3a Inhibits Angiogenesis and Maintains Atherosclerotic Plaque Stability in Atherosclerosis Mice

Evidence has demonstrated that microRNA-342-5p (miR-342-5p) is implicated in atherosclerosis (AS), but little is known regarding its intrinsic regulatory mechanisms. Here, we aimed to explore the effect of miR-342-5p targeting Wnt3a on formation of vulnerable plaques and angiogenesis of AS. ApoE^-/- mice were fed with high-fat feed for 16 w to replicate the AS vulnerable plaque model. miR-342-5p and Wnt3a expression in aortic tissues of AS were detected. The target relationship between miR-342-5p and Wnt3a was verified. Moreover, ApoE^-/- mice were injected with miR-342-5p antagomir and overexpression-Wnt3a vector to test their functions in serum lipid levels, inflammatory and oxidative stress-related cytokines, aortic plaque stability and angiogenesis in plaque of AS mice. miR-342-5p expression was enhanced and Wnt3a expression was degraded in aortic tissues of AS mice and miR-342-5p directly targeted Wnt3a. Up-regulating Wnt3a or down-regulating miR-342-5p reduced blood lipid content, inflammatory and oxidative stress levels, the vulnerability of aortic tissue plaque and inhibited angiogenesis in aortic plaque of AS mice. Functional studies show that depleting miR-342-5p can stabilize aortic tissue plaque and reduce angiogenesis in plaque in AS mice via restoring Wnt3a.

The effect of glutamine supplementation on serum levels of some inflammatory factors, oxidative stress, and appetite in COVID-19 patients: a case-control study

Background

Malnutrition is seen in COVID-19 patients, and reducing malnutrition with appropriate therapies may improve these patients' health. This case–control study aimed to assess and compare serum levels of some inflammatory factors, oxidative stress, and appetite in COVID-19 patients with respiratory infections that receive glutamine treatment with a control group.

Methods

In this study, patients who consented to use glutamine were considered as the case group and other patients who did not use glutamine were considered as a control group. Two hundred twenty-two COVID-19 patients (51.2 ± 6.7) using l-Glutamine and 230 COVID-19 patients (51.3 ± 8.2) with similar age, gender, and clinical status, as the control group, were included in the study. For 5 days, the case group consumed 10 g of glutamine supplement three times per day. At the end of the 5 days, blood samples were taken again to test for serum levels of IL1β, tumor necrosis factor-α, malondialdehyde, and total antioxidant capacity, then all data were analyzed.

Results

Serum levels of β-1 interleukin, tumor necrosis factor-α and hs-CRP were significantly reduced with five days of glutamine supplementation (p < 0.05), and patients’ appetite during 5 days of glutamine supplementation compared with the control group had a significant increase (p < 0.05).

Conclusion

Glutamine supplementation in COVID-19 patients with respiratory infection significantly reduces serum levels of interleukin-1 β, hs-CRP, and tumor necrosis factor-α and significantly increases appetite, so glutamine supplementation may be useful for COVID-19 patients in the hospital.

miR‑130b regulates PTEN to activate the PI3K/Akt signaling pathway and attenuate oxidative stress‑induced injury in diabetic encephalopathy

Diabetic encephalopathy (DE) is one of the main chronic complications of diabetes, and is characterized by cognitive defects. MicroRNAs (miRNAs/miRs) are widely involved in the development of diabetes-related complications. The present study evaluated the role of miR-130b in DE and investigated its mechanisms of action. PC12 cells and hippocampal cells were exposed to a high glucose environment to induce cell injuries to mimic the in vitro model of DE. Cells were transfected with miR-130b mimic, miR-130b inhibitor and small interfering RNA (si)-phosphatase and tensin homolog (PTEN) to evaluate the protective effect of the miR-130b/PTEN axis against oxidative stress in high glucose-stimulated cells involving Akt activity. Furthermore, the effect of agomir-130b was also assessed on rats with DE. The expression of miR-130b was reduced in the DE models in vivo and in vitro. The administration of miR-130b mimic increased the viability of high glucose-stimulated cells, prevented apoptosis, increased the activity of superoxide dismutase (SOD), decreased the malondialdehyde (MDA) content, activated Akt protein levels and inhibited the mitochondria-mediated apoptotic pathway. The administration of miR-130b inhibitor exerted opposite effects, while si-PTEN reversed the effects of miR-130b inhibitor. In vivo, the administration of agomir-130b attenuated cognitive disorders and neuronal damage, increased SOD activity, reduced the MDA content, activated Akt protein levels and inhibited the mitochondria-mediated apoptosis pathway in rats with DE. On the whole, these results suggest that miR-130b activates the PI3K/Akt signaling pathway to exert protective effects against oxidative stress injury via the regulation of PTEN in rats with DE.

Wnt-Independent and Wnt-Dependent Effects of APC Loss on the Chemotherapeutic Response

Resistance to chemotherapy occurs through mechanisms within the epithelial tumor cells or through interactions with components of the tumor microenvironment (TME). Chemoresistance and the development of recurrent tumors are two of the leading factors of cancer-related deaths. The Adenomatous Polyposis Coli (APC) tumor suppressor is lost in many different cancers, including colorectal, breast, and prostate cancer, and its loss correlates with a decreased overall survival in cancer patients. While APC is commonly known for its role as a negative regulator of the WNT pathway, APC has numerous binding partners and functional roles. Through APC's interactions with DNA repair proteins, DNA replication proteins, tubulin, and other components, recent evidence has shown that APC regulates the chemotherapy response in cancer cells. In this review article, we provide an overview of some of the cellular processes in which APC participates and how they impact chemoresistance through both epithelial- and TME-derived mechanisms.