Oxidative and endoplasmic reticulum stress is impaired in leukocytes from metabolically unhealthy vs healthy obese individuals

Effects of flaxseed supplementation on inflammatory biomarkers: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Several studies reported the benefits of flaxseed on inflammatory biomarkers, while others reported conflicting findings. Thus, the aim of this meta-analysis was to assess the impacts of flaxseed on inflammatory biomarkers in adults. Databases including Embase, PubMed, Scopus, and Web of Sciences were searched till February 2024. The 54 RCTs were included in the final analysis, which involved 3000 individuals from 12 countries. Overall, the flaxseed supplementation had a significant reduction in C-reactive protein (CRP) (SMD = -0.46; 95 % CI: -0.70, -0.23, P < 0.001; I2 = 82.9 %, P < 0.001), and interleukin 6 (IL-6) (SMD = -0.64, 95 % CI: -1.13, -0.16, P = 0.010; I2 = 92.7, P < 0.001). Furthermore, flaxseed did not significantly change the concentration of tumor necrosis factor α (TNF-α) (SMD = -0.17; 95 % CI: -0.63, 0.29, P = 0.467; I2 = 92, P < 0.001). Flaxseed supplementation significantly decreased serum concentrations of CRP and IL-6, but not TNF-a. Thus, this meta-analysis suggests that the current evidence supports the potential benefits of flaxseed in managing inflammatory conditions.

Dietary Phytochemical Index in Relation to Metabolic Health Status, Serum Adropin, and Brain-Derived Neurotrophic Factor Levels in Adults

Background

Little is known about the relationship between dietary intake of phytochemicals with metabolic health status and underlying mechanisms.

Objectives

Little is known about the relationship between dietary intake of phytochemicals with metabolic health status and underlying mechanisms. We hypothesized that dietary phytochemical index (DPI) improves metabolic health status by ameliorating serum concentrations of brain-derived neurotrophic factor (BDNF) and adropin.

Methods

A cross-sectional study was performed in 527 adults (286 males and 241 females). The dietary intakes of participants were collected by a 168-item food frequency questionnaire, and DPI was estimated as a percentage of energy intake derived from phytochemical-rich foods. Anthropometric variables, blood pressure, glycemic and lipid profiles, and biochemical variables were assessed. The metabolically unhealthy (MU) phenotype was determined based on the definition presented by Wildman et al.

Results

The MU phenotype was identified in 51.4% of male and 32.0% of female participants. Participants in the third tertile of DPI had 59% lower odds of MU than those in the first tertile (OR: 0.41; 95% CI: 0.19, 0.87) after considering potential confounders. Stratified analysis by sex and body mass index indicated that DPI was inversely related to MU phenotype in females (OR: 0.28; 95% CI: 0.08, 0.97) and normal-weight individuals (OR: 0.11; 95% CI: 0.02, 0.62). DPI was also inversely associated with hyperglycemia, hypertriglyceridemia, and chronic inflammation. Nonsignificant reduced odds of low BDNF (OR: 0.87; 95% CI: 0.42, 1.84) and adropin (OR: 0.75; 95% CI: 0.31, 1.79) were observed in individuals in the top tertile of DPI compared with those in the bottom tertile.

Conclusions

This study showed that individuals with higher dietary intake of phytochemicals had lower odds of MU, particularly females and normal-weight individuals. No significant relationship was observed between serum BDNF and adropin with phytochemical intake.

Effect of a Very Low-Calorie Diet on Oxidative Stress, Inflammatory and Metabolomic Profile in Metabolically Healthy and Unhealthy Obese Subjects

The purpose of the study was to determine the impact of weight loss through calorie restriction on metabolic profile, and inflammatory and oxidative stress parameters in metabolically healthy (MHO) and unhealthy (MUHO) obese individuals. A total of 74 subjects (34 MHO and 40 MUHO) received two cycles of a very low-calorie diet, alternating with a hypocaloric diet for 24 weeks. Biochemical, oxidative stress, and inflammatory markers, as well as serum metabolomic analysis by nuclear magnetic resonance, were performed at baseline and at the end of the intervention. After the diet, there was an improvement in insulin resistance, as well as a significant decrease in inflammatory parameters, enhancing oxidative damage, mitochondrial membrane potential, glutathione, and antioxidant capacity. This improvement was more significant in the MUHO group. The metabolomic analysis showed a healthier profile in lipoprotein profile. Lipid carbonyls also decrease at the same time as unsaturated fatty acids increase. We also display a small decrease in succinate, glycA, alanine, and BCAAs (valine and isoleucine), and a slight increase in taurine. These findings show that moderate weight reduction leads to an improvement in lipid profile and subfractions and a reduction in oxidative stress and inflammatory markers; these changes are more pronounced in the MUHO population.

Differences in the levels of inflammatory markers between metabolically healthy obese and other obesity phenotypes in adults: A systematic review and meta-analysis

AIMS

The aim of this study was to systematically review and analyze differences in the levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) comparing metabolically healthy but obese (MHO) with metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), and metabolically unhealthy obese (MUO) subjects.

DATA SYNTHESIS

We searched PubMed, Embase, Web of Science, and Scopus for studies that matched the relevant search terms. Differences in inflammatory marker levels between MHO and the other three phenotypes were pooled as standardized mean differences (SMD) or differences of medians (DM) using a random-effects model. We included 91 studies reporting data on 435,007 individuals. The CRP levels were higher in MHO than in MHNO subjects (SMD = 0.63, 95% CI: 0.49, 0.76; DM = 0.83 mg/L, 95% CI: 0.56, 1.11). The CRP levels were higher in MHO than in MUNO subjects (SMD = 0.16, 95% CI: 0.05, 0.28; DM = 0.39 mg/L, 95% CI: 0.09, 0.69). The CRP levels were lower in MHO than in MUO individuals (SMD = -0.43, 95% CI: -0.54, -0.31; DM = -0.82 mg/L, 95% CI: -1.16, -0.48). The IL-6 levels in MHO were higher than in MHNO while lower than in MUO subjects. The TNF-α levels in MHO were higher than in MHNO individuals.

CONCLUSIONS

This review provides evidence that CRP levels in MHO are higher than in MHNO and MUNO subjects but lower than in MUO individuals. Additionally, IL-6 levels in MHO are higher than in MHNO but lower than in MUO subjects, and TNF-α levels in MHO are higher than in MHNO individuals.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO number: CRD42021234948.

The potential role of omentin-1 in obesity-related metabolic dysfunction-associated steatotic liver disease: evidence from translational studies

BACKGROUND

Obesity, characterized by visceral adipose tissue (VAT) expansion, is closely associated with metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). Recent research has highlighted the crucial role of the adipose tissue-liver axis in the development of MASLD. In this study, we investigated the potential role of omentin-1, a novel adipokine expressed by VAT, in obesity-related MASLD pathogenesis.

METHODS

Through in silico analysis of differentially expressed genes in VAT from obese patients with and without MASH, we identified omentin-1 as a significant candidate. To validate our findings, we measured omentin-1 levels in VAT and plasma of lean controls and obese patients with biopsy-proven MASLD. Additionally, we assessed omentin-1 expression in the VAT of diet-induced mice MASLD model. In vitro and ex vivo studies were conducted to investigate the effects of omentin-1 on MASLD-related mechanisms, including steatosis, inflammation, endoplasmic reticulum (ER) stress, and oxidative stress. We also analyzed the impact of D-glucose and insulin on VAT omentin-1 levels ex vivo.

RESULTS

Compared to the lean group, the obese groups exhibited significantly lower VAT and plasma levels of omentin-1. Interestingly, within the obese groups, omentin-1 is further decreased in MASH groups, independent of fibrosis. Likewise, VAT of mice fed with high-fat diet, showing histological signs of MASH showed decreased omentin-1 levels as compared to their control diet counterpart. In vitro experiments on fat-laden human hepatocytes revealed that omentin-1 did not affect steatosis but significantly reduced TNF-α levels, ER stress, and oxidative stress. Similar results were obtained using ex vivo VAT explants from obese patients upon omentin-1 supplementation. Furthermore, omentin-1 decreased the mRNA expression of NF-κB and mitogen-activated protein kinases (ERK and JNK). Ex vivo VAT explants showed that D-glucose and insulin significantly reduced omentin-1 mRNA expression and protein levels.

CONCLUSIONS

Collectively, our findings suggest that reduced omentin-1 levels contribute to the development of MASLD. Omentin-1 supplementation likely exerts its beneficial effects through the inhibition of the NF-κB and MAPK signaling pathways, and it may additionally play a role in the regulation of glucose and insulin metabolism. Further research is warranted to explore omentin-1 as a potential therapeutic target and/or biomarker for MASLD.

Adherence to the Mediterranean diet as a possible additional tool to be used for screening the metabolically unhealthy obesity (MUO) phenotype

BACKGROUND

The terms metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) categorize subjects with obesity based on the presence or absence of cardio-metabolic risk factors. Detecting MUO phenotype is crucial due to the high risk of cardio-metabolic complications, requiring tailored and intensive follow-up. However, diagnosing MUO is time-consuming and costly. Thus, we aimed to investigate the role of Mediterranean diet (MD) in determining MHO/MUO phenotypes and whether adherence to MD could serve as an additional screening tool for MUO phenotype.

METHODS

The study population of this cross-sectional observational study consisted of 275 subjects with obesity. We assessed their lifestyle habits (physical activity and smoking habits), anthropometric measurements (weight, height, waist circumference, body mass index), blood pressure, metabolic parameters, inflammatory marker (high sensitivity C reactive protein levels), adherence to MD (by PREvención con DIetaMEDiterránea (PREDIMED) questionnaire), and MHO/MUO phenotypes.

RESULTS

The study included 275 individuals with obesity (256F/19M; 34.0 ± 10.5 years; BMI 38.3 ± 5.95 kg/m2). Among them, 114 (41.5%) exhibited MHO phenotype, while 161 (58.5%) had MUO phenotype. MHO phenotype exhibited favorable anthropometric and cardio-metabolic profiles, characterized by lower waist circumference (p < 0.001), BMI (p < 0.001), insulin resistance (p < 0.001), blood pressure (p < 0.001), inflammation (p < 0.001), and lipid levels (p < 0.001) compared to MUO phenotype. Notably, we found that MHO phenotype had higher adherence to MD (p < 0.001) and consumed more extra virgin olive oil (EVOO) (p < 0.001), vegetables (p < 0.001), fruits (p < 0.001), legumes (p = 0.001), fish (p < 0.001), wine (p = 0.008), and nuts (p = 0.001), while reporting lower intake of red/processed meats (p < 0.001), butter, cream, margarine (p = 0.008), soda drinks (p = 0.006), and commercial sweets (p = 0.002) compared to MUO phenotype. Adherence to MD (p < 0.001) and EVOO (p = 0.015) intake were identified as influential factors in determining the presence of MUO/MHO phenotypes. Furthermore, a PREDIMED score < 5 proved to be the most sensitive and specific cut-point value for predicting the presence of MUO phenotype (p < 0.001).

CONCLUSION

High adherence to MD was associated with MHO phenotype. Moreover, we suggest that a specific cut-off of the PREDIMED score could be an indicator to discriminate patients with MUO/MHO phenotypes and therefore help in identifying patients at higher cardiovascular risk who will require specific dietary intervention.

Sarcopenic Obesity: Involvement of Oxidative Stress and Beneficial Role of Antioxidant Flavonoids

Sarcopenic obesity, which refers to concurrent sarcopenia and obesity, is characterized by decreased muscle mass, strength, and performance along with abnormally excessive fat mass. Sarcopenic obesity has received considerable attention as a major health threat in older people. However, it has recently become a health problem in the general population. Sarcopenic obesity is a major risk factor for metabolic syndrome and other complications such as osteoarthritis, osteoporosis, liver disease, lung disease, renal disease, mental disease and functional disability. The pathogenesis of sarcopenic obesity is multifactorial and complicated, and it is caused by insulin resistance, inflammation, hormonal changes, decreased physical activity, poor diet and aging. Oxidative stress is a core mechanism underlying sarcopenic obesity. Some evidence indicates a protective role of antioxidant flavonoids in sarcopenic obesity, although the precise mechanisms remain unclear. This review summarizes the general characteristics and pathophysiology of sarcopenic obesity and focuses on the role of oxidative stress in sarcopenic obesity. The potential benefits of flavonoids in sarcopenic obesity have also been discussed.

Expression and localization of NRF2/Keap1 signalling pathway genes in mouse preimplantation embryos exposed to free fatty acids

Obese women experience greater incidence of infertility, with reproductive tracts exposing preimplantation embryos to elevated free fatty acids (FFA) such as palmitic acid (PA) and oleic acid (OA). PA treatment impairs mouse preimplantation development in vitro, while OA co-treatment rescues blastocyst development of PA treated embryos. In the present study, we investigated the effects of PA and OA treatment on NRF2/Keap1 localization, and relative antioxidant enzyme (Glutathione peroxidase; Gpx1, Catalase; Cat, Superoxide dismutase; Sod1 and γ-Glutamylcysteine ligase catalytic unit; Gclc) mRNA levels, during in vitro mouse preimplantation embryo development. Female mice were superovulated, mated, and embryos cultured in the presence of bovine Serum albumin (BSA) control or PA, or OA, alone (each at 100 μM) or PA + OA combined (each at 100 μM) treatment. NRF2 displayed nuclear localization at all developmental stages, whereas Keap1 primarily displayed cytoplasmic localization throughout control mouse preimplantation development in vitro. Relative transcript levels of Nrf2, Keap1, and downstream antioxidants significantly increased throughout control mouse preimplantation development in vitro. PA treatment significantly decreased blastocyst development and the levels of nuclear NRF2, while OA and PA + OA treatments did not. PA and OA treatments did not impact relative mRNA levels of Nrf2, Keap1, Gpx1, Cat, Sod1 or Gclc. Our outcomes demonstrate that cultured mouse embryos display nuclear NRF2, but that PA treatment reduces nuclear NRF2 and thus likely impacts NRF2/KEAP1 stress response mechanisms. Further studies should investigate whether free fatty acid effects on NRF2/KEAP1 contribute to the reduced fertility displayed by obese patients.

The Harm of Metabolically Healthy Obese and the Effect of Exercise on Their Health Promotion

Obesity and obesity-related diseases [type 2 diabetes, cardiovascular disease (CVD), and cancer] are becoming more common, which is a major public health concern. Metabolically healthy obesity (MHO) has become a type of obesity, accounting for a large proportion of obese people. MHO is still harmful to health. It was discovered that MHO screening criteria could not well reflect health hazards, whereas visceral fat, adiponectin pathway, oxidative stress, chronic inflammation, and histological indicators at the microlevel could clearly distinguish MHO from health control, and the biological pathways involved in these micro indicators were related to MHO pathogenesis. This review reveals that MHO’s micro metabolic abnormality is the initial cause of the increase of disease risk in the future. Exploring the biological pathway of MHO is important in order to develop an effective mechanism-based preventive and treatment intervention strategy. Exercise can correct the abnormal micro metabolic pathway of MHO, regulate metabolic homeostasis, and enhance metabolic flexibility. It is a supplementary or possible alternative to the traditional healthcare prevention/treatment strategy as well as an important strategy for reducing MHO-related health hazards.

Circulating TRB3 and GRP78 levels in type 2 diabetes patients: crosstalk between glucose homeostasis and endoplasmic reticulum stress

PURPOSE

Endoplasmic reticulum (ER) stress is implicated in the development of type 2 diabetes mellitus (T2DM) and insulin resistance. Tribbles homolog 3 (TRB3) is a pseudokinase upregulated by ER stress and hyperglycemia. Glucose-regulated protein 78 (GRP78) is an ER stress protein that is overexpressed under ER stress conditions. The current study aimed to investigate serum levels of TRB3 and GRP78, as an ER stress marker, in T2DM patients and their correlations with the metabolic profile.

METHODS

Fifty-seven patients with type 2 diabetes and 23 healthy control subjects were evaluated for serum concentrations of TRB3, GRP78, and AGEs by enzyme-linked immunosorbent assay (ELISA). Fasting plasma glucose (FPG), HbA1c, lipid profile, TNF-α and insulin were also measured, and insulin resistance was calculated using a homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

Serum concentrations of TRB3, GRP78, AGEs, and TNF-α were significantly higher in T2DM patients compared to the healthy controls. Moreover, a statistically significant positive correlation was observed between plasma concentrations of TRB3 and FPG, HbA1c, HOMA-IR, and AGE. GRP78 levels were positively correlated with HbA1c and AGEs. There was also a positive correlation between GRP78 and TRB3. AGEs levels were positively correlated with the levels of FPG, HbA1c, HOMA-IR, and TNF-α.

CONCLUSION

The current findings suggest that TRB3 and GRP78 may contribute to the pathogenesis of T2DM and might be considered as a therapeutic targets for the treatment of this disease.

The Effect of Daily Methylsulfonylmethane (MSM) Consumption on High-Density Lipoprotein Cholesterol in Healthy Overweight and Obese Adults: A Randomized Controlled Trial

Interventions to decrease inflammation and improve metabolic function hold promise for the prevention of obesity-related diseases. Methylsulfonylmethane (MSM) is a naturally occurring compound that demonstrates antioxidant and anti-inflammatory effects. Improvements in measures of metabolic health have been observed in mouse models of obesity and diabetes following MSM treatment. However, the effects of MSM on obesity-related diseases in humans have not been investigated. Therefore, the purpose of this investigation was to determine whether MSM supplementation improves cardiometabolic health, and markers of inflammation and oxidative status. A randomized, double-blind, placebo-controlled design was utilized with a total of 22 overweight or obese adults completing the study. Participants received either a placebo (white rice flour) or 3 g MSM daily for 16 weeks. Measurements occurred at baseline and after 4, 8, and 16 weeks. Outcome measures included fasting glucose, insulin, blood lipids, blood pressure, body composition, metabolic rate, and markers of inflammation and oxidative status. The primary finding of this work shows that high-density lipoprotein cholesterol was elevated at 8 and 16 weeks of daily MSM consumption compared to baseline, (p = 0.008, p = 0.013). Our findings indicate that MSM supplementation may improve the cholesterol profile by resulting in higher levels of high-density lipoprotein cholesterol.

Comparisons of the effects of different flaxseed products consumption on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases: systematic review and a dose-response meta-analysis of randomized controlled trials

BACKGROUND

Flaxseed is widely used as a functional food for its rich sources of linolenic acid, lignans and dietary fibers in the world. This systematic review and dose-response meta-analysis on randomized controlled trials (RCTs) is first to evaluate effects of different flaxseed products (whole flaxseed, oil and lignans) on lipid profiles, inflammatory and anthropometric parameters in patients with dyslipidemia related diseases.

METHODS

Literature search was performed in PubMed, Embase, Cochrane Central, Scopus, and Web of Science from the inception dates to January, 2020. Weighted mean differences with the 95% confidence interval (CI) were pooled using fix or random-effects models.

RESULTS

Thirty-one RCTs involving 1,698 participants were included. The present meta-analysis revealed that flaxseed consumption had an overall beneficial effect on serum TC, LDL-C, TG, apo B and IL-6 in patients with dyslipidemia related diseases, but not on apo A, HDL-C, hs-CRP, CRP and anthropometric indices. However, different flaxseed products showed obviously different effects. Whole flaxseed supplementation significantly reduced TC (- 11.85 mg/dl, 95% CI - 20.12 to - 3.57, P = 0.005), LDL-C (- 10.51 mg/dl, 95% CI - 14.96 to - 6.06, P < 0.001), TG (- 19.77 mg/dl, 95% CI - 33.61 to - 5.94, P = 0.005), apolipoprotein B (- 5.73 mg/dl, 95% CI - 7.53 to - 3.93, P < 0.001), TC/HDL-C (- 0.10, 95% CI - 0.19 to - 0.003, P = 0.044) and weight (- 0.40 kg, 95% CI - 0.76 to - 0.05, P = 0.027); Lignans supplementation significantly reduced TC (- 17.86 mg/dl, P = 0.004), LDL-C (- 15.47 mg/dl, P < 0.001) and TC/HDL-C (- 0.45, P = 0.04). Although flaxseed oil supplementation had no such lowering-effect on lipid, meta-analysis revealed its lowering-effect on IL-6 (- 0.35 pg/ml, P = 0.033) and hs-CRP (- 1.54 mg/l, P = 0.004). Subgroup analysis revealed that whole flaxseed decreased TC, LDL-C and TG levels irrespective of country and the intervention time prescribed, but was more pronounced when the dose of whole flaxseed was ≤ 30 g/day (TC: WMD - 13.61 mg/mL; LDL-C: WMD - 10.52 mg/mL; TG: WMD - 23.52 mg/mL), rather not a dose > 30 g/day. Moreover, a linear relationship between dose of whole flaxseed and absolute changes in C-reactive protein (P = 0.036) and a nonlinear relationship between with IL-6 (P < 0.001) were detected.

CONCLUSIONS

Flaxseed intervention suggested the positive effects on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases. Of these, whole flaxseed and lignans play an important role in reducing blood lipid, while flaxseed oil mainly plays in anti-inflammatory. Lipid- and weight-lowering was significant when whole flaxseed was consumed at doses < 30 mg/d, for lipid status with mixed dyslipidemia and patients with BMI > 25.

GPX7 Facilitates BMSCs Osteoblastogenesis via ER Stress and mTOR Pathway

Emerging evidence indicates extensive oxidative stress is a consequence of obesity which impairs bone formation. Glutathione peroxidase 7 (GPX7) is a conserved endoplasmic reticulum (ER) retention protein, lacking of which causes accumulation of reactive oxygen species (ROS) and promotes adipogenesis. Since the imbalance between osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cell (BMSC) leads to severe bone diseases such as osteoporosis, it is critical to investigate the potential protective role of Gpx7 in osteogenesis. Here, we provide evidence that deficiency of Gpx7 reduces osteogenesis, but increases adipogenesis in both human BMSCs (hBMSCs) and mouse mesenchymal stem cell line. Interestingly, further studies indicate this defect can be alleviated by the ER stress antagonist, but not the ROS inhibitor, unveiling an unexpected finding that, unlike adipogenesis, lacking of Gpx7 inhibits osteogenesis mediating by induced ER stress instead of enhanced ROS. Furthermore, the mTOR signalling pathway is found down‐regulation during osteogenic differentiation in Gpx7‐deficient condition, which can be rescued by relief of ER stress. Taken together, for the first time we identify a novel function of Gpx7 in BMSCs’ osteogenic differentiation and indicate that Gpx7 may protect against osteoporotic deficits in humans through ER stress and mTOR pathway interplay.

Transitions in Metabolic Health and Associations With Arterial Stiffness Progression Across Body Mass Index Categories

[Figure: see text].

Obesity, metabolic health and omics: Current status and future directions

The growing obesity epidemic is becoming a major public health concern, and the associated costs represent a considerable burden on societies. Among the most common complications of severe obesity are the development of hypertension, dyslipidemia, type 2 diabetes, cardiovascular disease, and various types of cancer. Interestingly, some obese individuals have a favorable metabolic profile and appear to be somehow protected from the detrimental effects of excessive adipose tissue accumulation. These individuals remain normoglycemic, insulin sensitive, and hypotensive with proper blood lipid levels, despite their high body mass index and/or waist circumference. Multiple independent observations have led to the concept of the metabolically healthy obese (MHO) phenotype, yet no consensus has been reached to date regarding a universal definition or the main mechanism behind this phenomenon. Recent technological advances and the use of high-throughput analysis techniques have revolutionized different areas of biomedical research. A multi-omics approach, which is used to investigate changes at different molecular levels in an organism or tissue, may provide valuable insights into the interplay between the molecules or pathways and the roles of different factors involved in the mechanisms underlying metabolic health deterioration. The aim of this review is to present the current status regarding the use of omics technologies to investigate the MHO phenotype, as well as the results of targeted analyses conducted in MHO individuals.

Metabolic Syndrome and Autophagy: Focus on HMGB1 Protein

Metabolic syndrome (MetS) affects the population worldwide and results from several factors such as genetic background, environment and lifestyle. In recent years, an interplay among autophagy, metabolism, and metabolic disorders has become apparent. Defects in the autophagy machinery are associated with the dysfunction of many tissues/organs regulating metabolism. Metabolic hormones and nutrients regulate, in turn, the autophagy mechanism. Autophagy is a housekeeping stress-induced degradation process that ensures cellular homeostasis. High mobility group box 1 (HMGB1) is a highly conserved nuclear protein with a nuclear and extracellular role that functions as an extracellular signaling molecule under specific conditions. Several studies have shown that HMGB1 is a critical regulator of autophagy. This mini-review focuses on the involvement of HMGB1 protein in the interplay between autophagy and MetS, emphasizing its potential role as a promising biomarker candidate for the early stage of MetS or disease's therapeutic target.

Characterization of Differentially Expressed Circulating miRNAs in Metabolically Healthy versus Unhealthy Obesity

Obese individuals without metabolic comorbidities are categorized as metabolically healthy obese (MHO). MicroRNAs (miRNAs) may be implicated in MHO. This cross-sectional study explores the link between circulating miRNAs and the main components of metabolic syndrome (MetS) in the context of obesity. We also examine oxidative stress biomarkers in MHO vs. metabolically unhealthy obesity (MUO). We analysed 3536 serum miRNAs in 20 middle-aged obese individuals: 10 MHO and 10 MUO. A total of 159 miRNAs were differentially expressed, of which, 72 miRNAs (45.2%) were higher and 87 miRNAs (54.7%) were lower in the MUO group. In addition, miRNAs related to insulin signalling and lipid metabolism pathways were upregulated in the MUO group. Among these miRNAs, hsa-miR-6796-5p and hsa-miR-4697-3p, which regulate oxidative stress, showed significant correlations with glucose, triglycerides, HbA1c and HDLc. Our results provide evidence of a pattern of differentially expressed miRNAs in obesity according to MetS, and identify those related to insulin resistance and lipid metabolism pathways.

Mitochondria and T2D: Role of Autophagy, ER Stress, and Inflammasome

Type 2 diabetes (T2D) is one of the main current threats to human health. Both T2D and its numerous clinical complications are related to mitochondrial dysfunction and oxidative stress. Over the past decade, great progress has been made in extending our knowledge about the signaling events regulated by mitochondria. However, the links among mitochondrial impairment, oxidative stress, autophagy, endoplasmic reticulum (ER) stress, and activation of the inflammasome still need to be clarified. In light of this deficit, we aim to provide a review of the existing literature concerning the complicated crosstalk between mitochondrial impairment, autophagy, ER stress, and the inflammasome in the molecular pathogenesis of T2D.

Systemic Oxidative Stress and Visceral Adipose Tissue Mediators of NLRP3 Inflammasome and Autophagy Are Reduced in Obese Type 2 Diabetic Patients Treated with Metformin

Obesity is a low-grade inflammatory condition affecting a range of individuals, from metabolically healthy obese (MHO) subjects to type 2 diabetes (T2D) patients. Metformin has been shown to display anti-inflammatory properties, though the underlying molecular mechanisms are unclear. To study whether the effects of metformin are mediated by changes in the inflammasome complex and autophagy in visceral adipose tissue (VAT) of obese patients, a biopsy of VAT was obtained from a total of 68 obese patients undergoing gastric bypass surgery. The patients were clustered into two groups: MHO patients and T2D patients treated with metformin. Patients treated with metformin showed decreased levels of all analyzed serum pro-inflammatory markers (TNFα, IL6, IL1β and MCP1) and a downwards trend in IL18 levels associated with a lower production of oxidative stress markers in leukocytes (mitochondrial ROS and myeloperoxidase (MPO)). A reduction in protein levels of MCP1, NFκB, NLRP3, ASC, ATG5, Beclin1 and CHOP and an increase in p62 were also observed in the VAT of the diabetic group. This downregulation of both the NLRP3 inflammasome and autophagy in VAT may be associated with the improved inflammatory profile and leukocyte homeostasis seen in obese T2D patients treated with metformin with respect to MHO subjects and endorses the cardiometabolic protective effect of this drug.

Effect of high-fat diet on peripheral blood mononuclear cells and adipose tissue in early stages of diet-induced weight gain

Subcutaneous adipose tissue (scAT) and peripheral blood mononuclear cells (PBMC) play a significant role in obesity-associated systemic low-grade inflammation. High-fat diet (HFD) is known to induce inflammatory changes in both scAT and PBMC. However, the time course of the effect of HFD on these systems is still unknown. The aim of the present study was to determine the time course of the effect of HFD on PBMC and scAT. New Zealand white rabbits were fed HFD for 5 or 10 weeks (i.e. HFD-5 and HFD-10) or regular chow (i.e. control (CNT)-5 and CNT-10). Thereafter, metabolic and inflammatory parameters of PBMC and scAT were quantified. HFD induced hyperfattyacidaemia in HFD-5 and HFD-10 groups, with the development of insulin resistance in HFD-10, while no changes were observed in scAT lipid metabolism and inflammatory status. HFD activated the inflammatory pathways in PBMC of HFD-5 group and induced modified autophagy in that of HFD-10. The rate of fat oxidation in PBMC was directly associated with the expression of inflammatory markers and tended to inversely associate with autophagosome formation markers in PBMC. HFD affected systemic substrate metabolism, and the metabolic, inflammatory and autophagy pathways in PBMC in the absence of metabolic and inflammatory changes in scAT. Dietary approaches or interventions to avert HFD-induced changes in PBMC could be essential to prevent metabolic and inflammatory complications of obesity and promote healthier living.

Increased Oxidized High-Density Lipoprotein/High-Density Lipoprotein-Cholesterol Ratio as a Potential Indicator of Disturbed Metabolic Health in Overweight and Obese Individuals

BACKGROUND

We evaluated the qualitative characteristics of high-density lipoprotein (HDL) particles in metabolically healthy and unhealthy overweight and obese subjects.

METHODS

The study involved 115 subject individuals classified as metabolically healthy and unhealthy, as in overweight and obese groups. Commercial enzyme-linked immunosorbent assay (ELISA) kits were used to measure oxidized HDL (OxHDL) and serum amyloid A (SAA) concentrations. Lipoprotein subfractions were separated using nondenaturing gradient gel electrophoresis.

RESULTS

An independent association was shown between increased OxHDL/HDL-cholesterol ratio and the occurrence of metabolically unhealthy phenotype in the overweight and obese groups. The OxHDL/HDL-cholesterol ratio showed excellent and acceptable diagnostic accuracy in determination of metabolic health phenotypes (overweight group, AUC = 0.881; obese group, AUC = 0.765). Accumulation of smaller HDL particles in metabolically unhealthy subjects was verified by lipoprotein subfraction analysis. SAA concentrations did not differ significantly between phenotypes.

CONCLUSIONS

Increased OxHDL/HDL-cholesterol ratio may be a potential indicator of disturbed metabolic health in overweight and obese individuals.

Impact of metabolically healthy obesity on the risk of incident gastric cancer: a population-based cohort study

BACKGROUND

The risk of colon or breast cancer in metabolically healthy obese (MHO) were lower than that in metabolically abnormal obese (MAO). We hypothesized that the risk of incident gastric cancer in MHO is lower than that in MAO.

METHODS

This historical cohort study included 19,685 Japanese individuals who received health-checkup programs from 2003 to 2016. Each subject was classified as metabolically healthy (MH) (no metabolic abnormalities) or metabolically abnormal (MA) (one or more metabolic abnormalities), according to four metabolic factors (hypertension, impaired fasting glucose, hypertriglyceridemia and low HDL-cholesterol). Obese (O) or non-obese (NO) was classified by a BMI cutoff of 25.0 kg/m². Hazard ratios of metabolic phenotypes for incident gastric cancer were calculated by the Cox proportional hazard model with adjustments for age, sex, alcohol consumption, smoking and exercise.

RESULTS

Over the median follow-up period of 5.5 (2.9-9.4) years, incident rate of gastric cancer was 0.65 per 1000 persons-years. Incident rate of MHNO, MHO, MANO and MAO were 0.33, 0.25, 0.80 and 1.21 per 1000 persons-years, respectively. Compared with MHNO, the adjusted hazard ratios for development of gastric cancer were 0.69 (95% CI 0.04-3.39, p = 0.723) in MHO, 1.16 (95% CI 0.63-2.12, p = 0.636) in MANO and 2.09 (95% CI 1.10-3.97, p = 0.024) in MAO.

CONCLUSIONS

This study shows that individuals with MAO, but not those with MHO, had an elevated risk for incident gastric cancer. Thus, we should focus more on the presence of metabolic abnormalities rather than obesity itself for incident gastric cancer.

The Mitochondrial Antioxidant SS-31 Modulates Oxidative Stress, Endoplasmic Reticulum Stress, and Autophagy in Type 2 Diabetes

Mitochondrial dysfunction has been shown to play a central role in the pathophysiology of type 2 diabetes (T2D), and mitochondria-targeted agents such as SS-31 are emerging as a promising strategy for its treatment. We aimed to study the effects of SS-31 on leukocytes from T2D patients by evaluating oxidative stress, endoplasmic reticulum (ER) stress and autophagy. Sixty-one T2D patients and 53 controls were included. Anthropometric and analytical measurements were performed. We also assessed reactive oxygen species (ROS) production, calcium content, the expression of ER stress markers GRP78, CHOP, P-eIF2α, and autophagy-related proteins Beclin1, LC3 II/I, and p62 in leukocytes from T2D and control subjects treated or not with SS-31. Furthermore, we have evaluated the action of SS-31 on leukocyte-endothelium interactions. T2D patients exhibited elevated ROS concentration, calcium levels and presence of ER markers (GRP78 and CHOP gene expression, and GRP78 and P-eIF2α protein expression), all of which were reduced by SS-31 treatment. SS-31 also led to a drop in BECN1 gene expression, and Beclin1 and LC3 II/I protein expression in T2D patients. In contrast, the T2D group displayed reduced p62 protein levels that were restored by SS-31. SS-20 (with non-antioxidant activity) did not change any analyzed parameter. In addition, SS-31 decreased rolling flux and leukocyte adhesion, and increased rolling velocity in T2D patients. Our findings suggest that SS-31 exerts potentially beneficial effects on leukocytes of T2D patients modulating oxidative stress and autophagy, and ameliorating ER stress.

Transition from metabolically benign to metabolically unhealthy obesity and 10-year cardiovascular disease incidence: The ATTICA cohort study

BACKGROUND/OBJECTIVES

Metabolically benign obesity remains a scientific field of considerable debate. The aim of the present work was to evaluate whether metabolically healthy obese (MHO) status is a transient condition which propagates 10-year cardiovascular disease (CVD) onset.

METHODS

A prospective longitudinal study was conducted during 2001-2012, the ATTICA study studying 1514 (49.8%) men and 1528 (50.2%) women (aged >18 years old) free of CVD and residing in the greater Athens area, Greece. Follow-up assessment of first combined CVD event (2011-2012) was achieved in n = 2020 participants; of them, 317 (15.7%) incident cases were identified. Obesity was defined as body mass index ≥30 kg/m2 and healthy metabolic status as absence of all NCEP ATP III (2005) metabolic syndrome components (excluding waist circumference).

RESULTS

The MHO prevalence was 4.8% (n = 146) with 28.2% of obese participants presenting metabolically healthy status at baseline. Within this group, 52% developed unhealthy metabolic status during the 10-year follow up. MHO vs. metabolically healthy non-obese participants had a higher likelihood of presenting with 10-year CVD events, yet only the subset of them who lost their baseline status reached the level of significance (Hazard Ratio (HR) = 1.43, 95% Confidence Interval (95% CI) 1.02, 2.01). Sensitivity analyses revealed that MHO status was independently associated with elevated CVD risk in women and participants with low adherence to the Mediterranean diet, low grade inflammation, and insulin resistance.

CONCLUSIONS

MHO status is a transient condition where weight management is demanded to prevent the establishment of unhealthy cardiometabolic features. The existence of obese persons who remain "longitudinally" resilient to metabolic abnormalities is an emerging area of future research.

Moderate weight loss attenuates chronic endoplasmic reticulum stress and mitochondrial dysfunction in human obesity

OBJECTIVE

In obese patients undergoing caloric restriction, there are several potential mechanisms involved in the improvement of metabolic outcomes. The present study further explores whether caloric restriction can modulate endoplasmic reticulum (ER) stress and mitochondrial function, as both are known to be mechanisms underlying inflammation and insulin resistance (IR) during obesity.

METHODS

A total of 64 obese patients with BMI ≥35 kg/m2 underwent a dietary program consisting of 6 weeks of a very-low-calorie diet followed by 18 weeks of low-calorie diet. We evaluated changes in the metabolic and inflammatory markers -TNFα, hsCRP, complement component 3 (C3c), and retinol binding protein 4 (RBP4)-, in the ER stress markers and modulators -eIF2α-P, sXBP1, ATF6, JNK-P, CHOP, GRP78, and SIRT1-, and in mitochondrial function parameters -mitochondrial reactive oxygen species (mROS), glutathione peroxidase 1 (GPX1), cytosolic Ca2+, and mitochondrial membrane potential.

RESULTS

The dietary intervention produced an 8.85% weight loss associated with enhanced insulin sensitivity, a less marked atherogenic lipid profile, and a decrease in systemic inflammation (TNFα, hsCRP) and adipokine levels (RBP4 and C3c). Chronic ER stress was significantly reduced (ATF6-CHOP, JNK-P) and expression levels of SIRT1 and GRP78 - a Ca2+-dependent chaperone - were increased and accompanied by the restoration of Ca2+ depots. Furthermore, mROS production and mitochondrial membrane potential improvement were associated with the up-regulation of the antioxidant enzyme GPX1.

CONCLUSIONS

Our data provide evidence that moderate weight loss attenuates systemic inflammation and IR and promotes the amelioration of ER stress and mitochondrial dysfunction, increasing the expression of chaperones, SIRT1 and antioxidant GPX1.

Metabolically Healthy versus Unhealthy Morbidly Obese: Chronic Inflammation, Nitro-Oxidative Stress, and Insulin Resistance

Metabolically heathy obesity is characterised by the presence of obesity in the absence of metabolic disturbances. The aim of our study was to analyse pro-inflammatory, nitro-oxidative stress, and insulin-resistance (IR) markers in metabolically healthy morbidly obese (MHMO) with respect to metabolically unhealthy morbidly obese (MUHMO) with metabolic syndrome (MS) and to identify the potential predictors of MS in the MHMO group. Two groups of MHMO and MUHMO with MS were analysed. We evaluated serum high sensitivity C reactive protein (hsCRP), tumor necrosis factor alpha (TNF-α), chemerin, nitrite and nitrate (NOx), total oxidant status (TOS), total antioxidant response (TAR), fasting blood glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR.) MHMO have similar hsCRP and TNF-α values as the MUHMO with MS, while chemerin was significantly lower in MHMO. NOx was higher in MUHMO with MS patients, while no difference regarding TOS and TAR was found between the two groups. HOMA-IR and insulin values were lower in MHMO as compared to the MUHMO with MS group. Insulin, HOMA-IR, and chemerin were identified predictors of MS in MHMO. In conclusion, MHMO and MUHMO display similarities and differences in terms of chronic inflammation, nitro-oxidative stress, and IR. Markers of IR and chemerin are possible predictors of MS in MHMO.

Favourable metabolic profile sustains mitophagy and prevents metabolic abnormalities in metabolically healthy obese individuals

BACKGROUND

Obesity-mediated oxidative stress results in mitochondrial dysfunction, which has been implicated in the pathogenesis of metabolic syndrome and T2DM. Recently, mitophagy, a cell-reparative process has emerged as a key facet in maintaining the mitochondrial health, which may contribute to contain the metabolic abnormalities in obese individuals. However, the status of mitophagy in metabolically healthy obese (MHO) and metabolically abnormal diabetic obese (MADO) subjects remains to be elucidated. Hence, the present study aims to unravel the alterations in mitochondrial oxidative stress (MOS) and mitophagy in these subjects.

METHODS

60 subjects including MHNO (metabolically healthy non-obese), MHO and MADO were enrolled as per the Asian criteria for obesity (n = 20 each). Biochemical parameters, MOS indices, transcriptional and translational expression of mitophagy markers (PINK1, PARKIN, MFN2, NIX, LC3-II, and LAMP-2), and transmission electron microscopic (TEM) studies were performed in peripheral blood mononuclear cells.

RESULTS

The MHO subjects displayed a favorable metabolic profile, despite accompanied by an increased adiposity as compared to the MHNO group; while MADO group exhibited several metabolic abnormalities, inspite of similar body composition as MHO subjects. A progressive rise in the MOS was observed in MHO and MADO subjects as compared to the MHNO group, and it showed a positive and significant correlation with the body composition in these groups. Further, mitophagy remained unaltered in the MHO group, while it was significantly downregulated in the MADO group. In addition, TEM studies revealed a significant increase in the percentage of damaged mitochondria in MADO patients as compared to other groups, while MHO and MHNO groups did not show any significant alterations for the same.

CONCLUSION

A favorable metabolic profile and moderate levels of MOS in the MHO group may play a crucial role in the sustenance of mitophagy, which may further limit the aggravation of MOS, inflammation, and emergence of metabolic aberrations in contrast to MADO subjects, who exhibited multiple metabolic abnormalities and attenuated mitophagy. Therefore, these MHO subjects are likely to be at a lower risk of developing metabolic syndrome and T2DM.