N-Acetylcysteine (NAC) Ameliorates Lipid-Related Metabolic Dysfunction in Bone Marrow Stromal Cells-Derived Adipocytes

Fatty infiltration in the musculoskeletal system: pathological mechanisms and clinical implications

Fatty infiltration denotes the anomalous accrual of adipocytes in non-adipose tissue, thereby generating toxic substances with the capacity to impede the ordinary physiological functions of various organs. With aging, the musculoskeletal system undergoes pronounced degenerative alterations, prompting heightened scrutiny regarding the contributory role of fatty infiltration in its pathophysiology. Several studies have demonstrated that fatty infiltration affects the normal metabolism of the musculoskeletal system, leading to substantial tissue damage. Nevertheless, a definitive and universally accepted generalization concerning the comprehensive effects of fatty infiltration on the musculoskeletal system remains elusive. As a result, this review summarizes the characteristics of different types of adipose tissue, the pathological mechanisms associated with fatty infiltration in bone, muscle, and the entirety of the musculoskeletal system, examines relevant clinical diseases, and explores potential therapeutic modalities. This review is intended to give researchers a better understanding of fatty infiltration and to contribute new ideas to the prevention and treatment of clinical musculoskeletal diseases.

Selenium-dependent glutathione peroxidase 1 regulates transcription of elongase 3 in murine tissues

We have previously shown dysregulated lipid metabolism in tissues of glutathione peroxidase 1 (GPX1) overexpressing (OE) or deficient (KO) mice. This study explored underlying mechanisms of GPX1 in regulating tissue fatty acid (FA) biosynthesis. GPX1 OE, KO, and wild-type (WT) mice (n = 5, male, 3-6 months old) were fed a Se-adequate diet (0.3 mg/kg) and assayed for liver and adipose tissue FA profiles and mRNA levels of key enzymes of FA biosynthesis and redox-responsive transcriptional factors (TFs). These three genotypes of mice (n = 5) were injected intraperitoneally with diquat, ebselen, and N-acetylcysteine (NAC) at 10, 50, and 50 mg/kg of body weight, respectively, and killed at 0 and 12 h after the injections to detect mRNA levels of FA elongases and desaturases and the TFs in the liver and adipose tissue. A luciferase reporter assay with targeted deletions of mouse Elovl3 promoter was performed to determine transcriptional regulations of the gene by GPX1 mimic ebselen in HEK293T cells. Compared with WT, GPX1 OE and KO mice had 9-42% lower (p < 0.05) and 36-161% higher (p < 0.05) concentrations of C20:0, C22:0, and C24:0 in these two tissues, respectively, along with reciprocal increases and decreases (p < 0.05) of Elovl3 transcripts. Ebselen and NAC decreased (p < 0.05), whereas diquat decreased (p < 0.05), Elovl3 transcripts in the two tissues. Overexpression and knockout of GPX1 decreased (p < 0.05) and increased (p < 0.05) ELOVL3 levels in the two tissues, respectively. Three TFs (GABP, SP1, and DBP) were identified to bind the Elovl3 promoter (-1164/+33 base pairs). Deletion of DBP (-98/-86 base pairs) binding domain in the promoter attenuated (13%, p < 0.05) inhibition of ebselen on Elovl3 promoter activation. In summary, GPX1 overexpression down-regulated very long-chain FA biosynthesis via transcriptional inhibition of the Elovl3 promoter activation.

Effects of Mangiferin on LPS-Induced Inflammation and SARS-CoV-2 Viral Adsorption in Human Lung Cells

The growing interest in natural bioactive molecules, as an approach to many pathological contexts, is widely justified by the necessity to overcome the disadvantageous benefit-risk ratio related to traditional therapies. Among them, mangiferin (MGF) shows promising beneficial properties such as antioxidant, anti-inflammatory, and immunomodulatory effects. In this study, we aimed to investigate the antioxidant and anti-inflammatory properties of MGF on lipopolysaccharide (LPS)-induced lung NCI-H292 cells, focusing on its role against COVID-19 adsorption. In order to obtain this information, cells treated with LPS, with or without MGF, were analyzed performing wound healing, gene expression of inflammatory cytokines, GSH quantification, and JC-1 staining. Moreover, the inhibition of viral adsorption was evaluated microbiologically and the results were further confirmed by molecular docking analysis. In this regard, MGF downregulates the expression of several inflammatory factors, enhances GSH levels, promotes the wound healing rate, and restores the mitochondrial dysfunction caused by LPS. In addition, MGF significantly inhibits SARS-CoV-2 adsorption as shown by the gene expression of ACE2 and TMPRSS-2, and furtherly confirmed by microbiological and molecular modeling evaluation. Although more investigations are still needed, all data obtained constitute a solid background, demonstrating the cytoprotective role of MGF in inflammatory mechanisms including COVID-19 infection.

Retinoic acid-induced 1 gene haploinsufficiency alters lipid metabolism and causes autophagy defects in Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder characterized by cognitive and behavioral symptoms, obesity, and sleep disturbance, and no therapy has been developed to alleviate its symptoms or delay disease onset. SMS occurs due to haploinsufficiency of the retinoic acid-induced-1 (RAI1) gene caused by either chromosomal deletion (SMS-del) or RAI1 missense/nonsense mutation. The molecular mechanisms underlying SMS are unknown. Here, we generated and characterized primary cells derived from four SMS patients (two with SMS-del and two carrying RAI1 point mutations) and four control subjects to investigate the pathogenetic processes underlying SMS. By combining transcriptomic and lipidomic analyses, we found altered expression of lipid and lysosomal genes, deregulation of lipid metabolism, accumulation of lipid droplets, and blocked autophagic flux. We also found that SMS cells exhibited increased cell death associated with the mitochondrial pathology and the production of reactive oxygen species. Treatment with N-acetylcysteine reduced cell death and lipid accumulation, which suggests a causative link between metabolic dyshomeostasis and cell viability. Our results highlight the pathological processes in human SMS cells involving lipid metabolism, autophagy defects and mitochondrial dysfunction and suggest new potential therapeutic targets for patient treatment.

Bone Regeneration and Oxidative Stress: An Updated Overview

Bone tissue engineering is a complex domain that requires further investigation and benefits from data obtained over past decades. The models are increasing in complexity as they reveal new data from co-culturing and microfluidics applications. The in vitro models now focus on the 3D medium co-culturing of osteoblasts, osteoclasts, and osteocytes utilizing collagen for separation; this type of research allows for controlled medium and in-depth data analysis. Oxidative stress takes a toll on the domain, being beneficial as well as destructive. Reactive oxygen species (ROS) are molecules that influence the differentiation of osteoclasts, but over time their increasing presence can affect patients and aid the appearance of diseases such as osteoporosis. Oxidative stress can be limited by using antioxidants such as vitamin K and N-acetyl cysteine (NAC). Scaffolds and biocompatible coatings such as hydroxyapatite and bioactive glass are required to isolate the implant, protect the zone from the metallic, ionic exchange, and enhance the bone regeneration by mimicking the composition and structure of the body, thus enhancing cell proliferation. The materials can be further functionalized with growth factors that create a better response and higher chances of success for clinical use. This review highlights the vast majority of newly obtained information regarding bone tissue engineering, such as new co-culturing models, implant coatings, scaffolds, biomolecules, and the techniques utilized to obtain them.

Total flavonoids of Rhizoma Drynariae combined with calcium attenuate osteoporosis by reducing reactive oxygen species generation

In the present study, the effects of total flavonoids of Rhizoma Drynariae (TFRD) and calcium carbonate (CaCO₃) on osteoporosis (OP) were assessed in a rat model of OP. For this purpose, 36 Sprague-Dawley rats, aged 3 months, were randomly divided into a group undergoing sham surgery (sham-operated group), model group (OP group), CaCO₃ group (OP + CaCO₃ group), TFRD group (OP + TFRD group), TFRD combined with CaCO₃ group (OP + TFRD + CaCO₃ group) and TFRD and CaCO₃ combined with N-acetyl cysteine group (OP + TFRD + CaCO₃ + NAC group). The rat model of OP was established by bilateral ovariectomy. The changes in bone mineral density (BMD), bone volume parameters and bone histopathology in the rats from each group were observed. The levels of serum reactive oxygen species, superoxide dismutase (SOD), malondialdehyde, glutathione peroxidase (GSH-Px), interleukin (IL)-6, IL-1β, TNF-α, and the levels of bone tissue runt-related transcription factor 2 (RUNX2), osteoprotegerin (OPG), osteocalcin (BGP), PI3K, p-PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR) and p-mTOR were measured in the rats of each group. The induction of OP was associated with a marked decrease in BMD, bone mineral content, bone volume fraction and trabecular thickness, and decreased serum levels of SOD and GSH-Px. Moreover, the expressions of RUNX2, OPG, BGP were downregulated and an upregulation of p-PI3K, p-AKT and p-mTOR were observed in osteoporotic rats. However, treatment with TFRD and CaCO₃ restored all the aforementioned parameters to almost normal values. Furthermore, the findings on histopathological evaluation were consistent with the biochemical observations. Taken together, the findings of the present study demonstrated that TFRD and CaCO₃ significantly increased the antioxidant capacity in rats with OP, increased BMD and reduced bone mineral loss, and may be useful for the prevention and treatment of OP.

Mild exacerbation of obesity- and age-dependent liver disease progression by senolytic cocktail dasatinib + quercetin

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and represents a growing challenge in terms of prevention and treatment. A minority of affected patients develops inflammation, subsequently fibrosis, cirrhosis and hepatocellular carcinoma (HCC). HCC is a leading cause of cancer-related death. An increased number of senescent cells correlate with age-related tissue degeneration during NAFLD-induced HCC. Senolytics are promising agents that target selectively senescent cells. Previous studies showed that whereas a combination of the senolytic drugs dasatinib and quercetin (D + Q) reduced NAFLD in mice, D + Q lacked efficacy in removing doxorubicin-induced β-gal-positive senescent cells in human HCC xenografted mice. Whether D + Q has an effect on the age-associated spectrum of NAFLD-inflammation-HCC remains unknown.

METHODS

Here, we utilized an established model of age- and obesity-associated HCC, the low dose diethylnitrosamine (DEN)/high fat diet (HFD), a regimen promoting liver inflammation and tumorigenesis over a long period of 9 months. Four groups of mice each were created: group 1 included control untreated mice; group 2 included mice treated with D + Q; group 3 included mice undergoing the DEN/HFD protocol; group 4 included mice undergoing the DEN/HFD protocol with the administration of D + Q. At the end of the chemical/dietary regimen, we analyzed liver damage and cell senescence by histopathology, qPCR and immunoblotting approaches.

RESULTS

Unexpectedly, D + Q worsened liver disease progression in the DEN/HFD mouse model, slightly increasing histological damage and tumorigenesis, while having no effect on senescent cells removal.

CONCLUSIONS

In summary, using an animal model that fully recapitulates NAFLD, we demonstrate that these compounds are ineffective against age-associated NAFLD-induced HCC. Video Abstract.

Critical Assessment of In Vitro and In Vivo Models to Study Marrow Adipose Tissue

PURPOSE OF THE REVIEW

The purpose of this review is to describe the in vitro and in vivo methods that researchers use to model and investigate bone marrow adipocytes (BMAds).

RECENT FINDINGS

The bone marrow (BM) niche is one of the most interesting and dynamic tissues of the human body. Relatively little is understood about BMAds, perhaps in part because these cells do not easily survive flow cytometry and histology processing and hence have been overlooked. Recently, researchers have developed in vitro and in vivo models to study normal function and dysfunction in the BM niche. Using these models, scientists and clinicians have noticed that BMAds, which form bone marrow adipose tissue (BMAT), are able to respond to numerous signals and stimuli, and communicate with local cells and distant tissues in the body. This review provides an overview of how BMAds are modeled and studied in vitro and in vivo.

Bilirubin Safeguards Cardiorenal and Metabolic Diseases: a Protective Role in Health

PURPOSE OF REVIEW

To discuss recent advances indicating that bilirubin safeguards against cardiorenal and metabolic diseases.

RECENT FINDINGS

Several investigations from human patient populations and experimental animal models have shown that bilirubin improves cardiorenal and metabolic dysfunction. The latest studies found an entirely new function of bilirubin suggesting that it acts as a hormone signaling molecule capable of activating nuclear receptors for burning fat, which may explain several of its protective actions. This review highlights the current findings (within the last 3 years) regarding cardiorenal and metabolic protective effects of bilirubin and the latest mechanism(s) that may be mediating these effects.

CRISPR Cas9-mediated deletion of biliverdin reductase A (BVRA) in mouse liver cells induces oxidative stress and lipid accumulation

Obesity is the predominant cause of non-alcoholic fatty liver disease (NAFLD), which is associated with insulin resistance and diabetes. NAFLD includes a spectrum of pathologies that starts with simple steatosis, which can progress to non-alcoholic steatohepatitis (NASH) with the commission of other factors such as the enhancement of reactive oxygen species (ROS). Biliverdin reductase A (BVRA) reduces biliverdin to the antioxidant bilirubin, which may serve to prevent NAFLD, and possibly the progression to NASH. To further understand the role of BVRA in hepatic function, we used CRISPR-Cas9 technology to target the Blvra gene in the murine hepa1c1c7 hepatocyte cell line (BVRA KO). BVRA activity and protein levels were significantly lower in BVRA KO vs. wild-type (WT) hepatocytes. Lipid accumulation under basal and serum-starved conditions was significantly (p < 0.05) higher in BVRA KO vs. WT cells. The loss of BVRA resulted in the reduction of mitochondria number, decreased expression of markers of mitochondrial biogenesis, uncoupling, oxidation, and fusion, which paralleled reduced mitochondrial oxygen consumption. BVRA KO cells exhibited increased levels of ROS generation and decreased levels of superoxide dismutase mRNA expression. In conclusion, our data demonstrate a critical role for BVRA in protecting against lipid accumulation and oxidative stress in hepatocytes, which may serve as a future therapeutic target for NAFLD and its progression to NASH.

In vitro mitochondrial-targeted antioxidant peptide induces apoptosis in cancer cells

Introduction

Reactive oxygen species (ROS) are major contributors to cancer and involved in numerous tumor proliferation signaling pathways. Mitochondria are the major ROS-producing organelles, and ROS are produced from the synthesis of adenosine triphosphate and cell metabolism.

Methods

A novel mitochondria-targeted peptide, namely KRSH, was synthesized and characterized. KRSH consists of four amino acids; lysine and arginine contain positively charged groups that help KRSH target the mitochondria, while tyrosine and cysteine neutralize excessive endogenous ROS, thereby inhibiting tumorigenesis.

Results

The results indicated that KRSH is specifically inhibiting the growth of HeLa and MCF-7 cancer cell lines. However, MCF10A cells can resist the effects of KRSH even in a relative higher concentration. The dichloro-dihydro-fluorescein diacetate and MitoSOX^TM Red assay suggested that KRSH drastically decreased the level of ROS in cancer cells. The mitochondrial depolarization assay indicated that treatment with KRSH at a dose of 50 nM may decrease the mitochondrial membrane potential leading to apoptosis of HeLa and MCF-7 cells.

Conclusion

In other studies, investigating rat liver mitochondria, the uptake of KRSH may reach 80% compared with that for mitoquinone. Therefore, KRSH was designed as a superior peptide antioxidant and a mitochondria-targeting anticancer agent.

Loss of hepatic PPARα promotes inflammation and serum hyperlipidemia in diet-induced obesity

Agonists for PPARα are used clinically to reduce triglycerides and improve high-density lipoprotein (HDL) cholesterol levels in patients with hyperlipidemia. Whether the mechanism of PPARα activation to lower serum lipids occurs in the liver or other tissues is unknown. To determine the function of hepatic PPARα on lipid profiles in diet-induced obese mice, we placed hepatocyte-specific peroxisome proliferator-activated receptor-α (PPARα) knockout (Ppara^HepKO) and wild-type (Ppara^fl/fl) mice on high-fat diet (HFD) or normal fat diet (NFD) for 12 wk. There was no significant difference in weight gain, percent body fat mass, or percent body lean mass between the groups of mice in response to HFD or NFD. Interestingly, the Ppara^HepKO mice on HFD had worsened hepatic inflammation and a significant shift in the proinflammatory M1 macrophage population. These changes were associated with higher hepatic fat mass and decreased hepatic lean mass in the Pparα^HepKO on HFD but not in NFD as measured by Oil Red O and noninvasive EchoMRI analysis (31.1 ± 2.8 vs. 20.2 ± 1.5, 66.6 ± 2.5 vs. 76.4 ± 1.5%, P < 0.05). We did find that this was related to significantly reduced peroxisomal gene function and lower plasma β-hydroxybutyrate in the Ppara^HepKO on HFD, indicative of reduced metabolism of fats in the liver. Together, these provoked higher plasma triglyceride and apolipoprotein B100 levels in the Ppara^HepKO mice compared with Ppara^fl/fl on HFD. These data indicate that hepatic PPARα functions to control inflammation and liver triglyceride accumulation that prevent hyperlipidemia.

Beneficial Effects of Pomegranate Peel Extract and Probiotics on Pre-adipocyte Differentiation

The beneficial effects of pomegranate are due to the ellagitannins and anthocyanins content, which are protective toward a wide variety of diseases including inflammatory diseases. Many investigators have reported that pomegranate waste (peel and seeds) extracts, made from waste product of industrial processing, show free radical scavenger and a potent antioxidant capacity. Pomegranate extracts (PEs) were also reported to possess noteworty antibacterial, antiviral, hypolipidemic, and anti-inflammatory bioactivities thanks to the polyphenolic compounds content, which includes punicalagins, gallic acid, and ellagic acid derivatives. The focus of the present manuscript was to study the prebiotic potentiality of a PE, soluble in water, and characterized through HPLC-PDA-ESI/MS ⁿ for its phenolic content. Moreover, since it has been reported that pomegranate extracts decreased the level of lipids in the blood and that a number of probiotic strains have been shown to affect adipogenesis in cell culture, this study was also performed to test the in vitro effects of PE and probiotic L. rhamnosus GG ATCC 53103 strain (LGG) on 3T3-L1 cell line. PE and probiotics substantially reduced the triglyceride content and intracellular lipid increase, compared to the control group. However, the combination treatment of PE and LGG filtered spent broth (SB) was the most effective in reducing triglyceride content and intracellular lipid accumulation. The mRNA expression levels of the main transcriptional factors implicated in adipocyte differentiation were substantially lower in 3T3-L1 cells treated with PE and LGG filtered SB. These results evidenced that a synergistic effect of probiotics and polyphenols contained in PE may affect in vitro adipogenesis and may contribute in development of new nutraceutical/probiotic-based remedies to prevent and to treat obesity.

High Glucose Level Impairs Human Mature Bone Marrow Adipocyte Function Through Increased ROS Production

Bone marrow adipocytes (BMAds) accumulate in aging, menopause, and metabolic diseases such as Type 2 diabetes. These osteoporotic conditions are associated with oxidative stress and hyperglycemia which are both considered as critical factors underlying bone fragility. Glucose excess and reactive oxygen species (ROS) are known to favor adipogenesis over osteoblastogenesis. In this study, we investigated whether high glucose exposure could determine dysfunction of mature BMAds, specifically through ROS production. The effects of low (LG, 5 mM) or high glucose (HG, 25 mM) concentrations were examined using human bone mesenchymal stromal cells (hBMSCs) in the time course of differentiation, and, up to 21 days once adipocytes were mature. HG did not alter the adipocyte differentiation process of hBMSCs. Yet, after 21 days under HG exposure, PPARG, CEBPA, and adiponectin mRNA expressions were decreased. These alterations were also observed following adipogenic inducer withdrawal as well as in adipocytes fully differentiated in LG then cultured in HG for the last 11 days. Without inducers, HG condition also led to decreased leptin mRNA level. Importantly, intracellular and extracellular ROS concentrations measured using Amplex Red were significantly raised by 50% under HG exposure. This rise was observed once adipocytes ended differentiation and was reproduced within the different cell culture settings without any cytotoxicity. Among genes involved in ROS metabolism, the mRNA level of the H₂O₂ generating enzyme NOX4 was found upregulated in the presence of HG. Following cell separation, mature BMAds were shown to overproduce ROS and to display the gene alterations in contrast to non-lipid-laden cells. Finally, a non-lethal treatment with a pro-oxidant agent under LG condition reduces the mRNA levels of PPARG, adiponectin, and leptin as the HG condition does in the absence of inducers, and amplifies the effect of glucose excess on gene expression. HG concentration drives mature BMAds toward altered expression of the main adipokines and transcriptional factors. These perturbations are associated with a rise in ROS generation likely mediated through enhanced expression of NOX4. Mature BMAds are thus responsive to changes in glucose and ROS concentrations, which is relevant regarding with their phenotype and function in age- or metabolic disease-related osteoporosis.