ARTICLE | doi:10.20944/preprints202204.0052.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: Carbohydrates; keto diet; IRS; C-peptide
Online: 7 April 2022 (04:03:54 CEST)
Abstract: Carbohydrates form the major source of energy in Asian diets. A lower carbohydrate diet became the recommended golden standard for healthy lifestyle. However, the effects of low-carbohydrates diet on health in apparently healthy individuals have been poorly studied, especially in relation to insulin resistance syndrome (IRS). A total of 120 healthy weight participants with no previous history of a major medical condition and an average BMI of ≤ 25kg/m2 were recruited. Self-reported dietary intake and objective physical activity by accelerometry were tracked for seven days. Participants were divided into three categories according to their dietary intake of carbohydrates. Blood samples were collected for metabolic markers analysis. HOMA of insulin resistance (HOMA-IR), β-cell function (HOMA-B) and C-peptide were used to evaluate glucose homeostasis. The consumption of low carbohydrates (less than 45% of total energy) significantly correlated with higher HOMA-IR, Lower HOMA-β % compared to moderate carbohydrate intake (between 45% to 65%). However, only the HOMA-β % was significantly influenced by carbohydrates intake. Moreover, low carbohydrates intake was significantly associated with elevated C-peptide secretion. The substitution of carbohydrates with other macronutrients, such as fat and proteins in the Atkins/ketogenic diet, resulted in a pronounced induction of IRS-related inflammatory markers; FGF2, IP-10, IL-6, IL-17A, MDC and reduction of IL-13. Overall, the presented data highlight, for the first time, that low carbohydrate intake results in significant glucose homeostasis imbalance that may be driven by a heightened state of inflammatory response.
ARTICLE | doi:10.20944/preprints202103.0708.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Adolescents; high sensitivity C-reactive protein; Insulin-like growth factor binding proteins; Obesity; Oxidized Low-Density Lipoprotein; Predictive diagnostics
Online: 29 March 2021 (16:33:20 CEST)
Insulin-like growth factor binding proteins (IGFBPs) are critical modulators of the metabolism. In adults, IGFBPs are associated with obesity and insulin resistance but the association of IGFBPs with metabolic homeostasis in children and adolescents is not fully characterized. In this study we investigated the association of plasma IGFBPs (IGFBP-1, 3 and 7) with weight status, central adiposity and cardiovascular disease markers Hs-CRP and Ox-LDL. A total of 420 adolescents (age 11-14 years) were randomly recruited from public middle schools in Kuwait. IGFBPs were measured using bead-based multiplexing while Hs-CRP and Ox-LDL were measured using ELISA. IGFBP-1 levels were significantly lower in obese and overweight participants compared to normal weight children. Only IGFBP-1 was negatively associated with waist circumference to height (WC/Ht) ratio. IGFBP-1 was negatively correlated with Hs-CRP while IGFBP-3 and IGFBP-7 were negatively correlated with Ox-LDL. These data demonstrate a robust negative association of IGFBP-1, but not IGFBP-3 or -7, with overweight and obesity, and the inflammation marker Hs-CRP. Central adiposity (WC/Ht ratio) was a stronger predictor of IGFBP-1 than BMI-for-age z-score. IGFBP-1 could thus be used as a sensitive predictive diagnostic tool for obesity and its subsequent effects in screening and monitoring of obesity-related metabolic complications in adolescents.
ARTICLE | doi:10.20944/preprints202307.1342.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: ER stress; metabolic stress; obesity; metabolic syndrome; inflammation; TNF-α; ROS; CHOP; HIF-1α; MAPK/NF-κB
Online: 20 July 2023 (02:35:45 CEST)
Obesity and metabolic syndrome involve chronic low-grade inflammation called metabolic inflammation as well as metabolic derangements from increased endotoxin and free fatty acids. It is debated whether the endoplasmic reticulum (ER) stress in monocytic cells can contribute to amplify metabolic inflammation; if so, by which mechanism(s). To test this, metabolic stress was induced in THP-1 monocytic cells by treatments with lipopolysaccharide (LPS), palmitic acid (PA), or oleic acid (OA), in the presence or absence of ER stressor thapsigargin (TG). Gene expression of tumor necrosis factor (TNF)-α and markers of ER/oxidative stress was determined by qRT-PCR, TNF-α protein by ELISA, ROS by DCFH-DA assay, HIF-1α/p38/ERK-1,2/NF-κB phosphorylation by immunoblotting, and insulin sensitivity by glucose-uptake assay. Regarding clinical analyses, adipose TNF-α was assessed by qRT-PCR/IHC and plasma TNF-α/hs-CRP/MDA/OX-LDL by ELISA. We found that the cooperative interaction between metabolic and ER stresses promoted TNF-α, ROS, CHOP, ATF6, SOD2, and NRF2 expression (P≤0.0183),. However, glucose uptake was not impaired. TNF-α amplification was dependent on HIF-1α/p38/NF-κB phosphorylation, while MAPK/NF-κB inhibitors and antioxidants/ROS scavengers attenuated TNF-α production (P≤0.05). Individuals with obesity displayed increased adipose TNF-α gene/protein expression as well as elevated plasma levels of TNF-α, CRP, MDA, and OX-LDL (P≤0.05). Our findings support a cooperative interaction between metabolic and ER stresses, favoring inflammation by triggering TNF-α production via the ROS/CHOP/HIF-1α and MAPK/NF-κB dependent mechanisms. This study also shows the therapeutic potential of ROS scavengers/anti-oxidants in inflammatory conditions involving metabolic/ER stresses.
ARTICLE | doi:10.20944/preprints202212.0194.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: Caveolin 1; Obesity; Adipose tissue; Metabolic inflammation; Cytokines; TNF-α; NF-κB
Online: 12 December 2022 (06:02:18 CET)
Obesity is characterized by chronic low-grade inflammation. Caveolin-1 (CAV1), a structural and functional protein found in adipose tissues (AT), is augmented in obese individuals. We aimed to define the inflammatory mediators that influence CAV1 gene regulation and associated mechanism in obesity. Using subcutaneous AT from 27 (7 lean/20 obese) normoglycemic individuals, in vitro human adipocyte models, and in vivo mice models, we found elevated CAV1 expression in obese AT and a positive correlation between the gene expression of CAV1, tumor necrosis factor alpha (TNF-α), and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB). CAV1 gene expression was associated with that of proinflammatory cytokines/chemokines, and their cognate receptor (r ≥ 0.447, p ≤ 0.030) but not with anti-inflammatory markers. CAV1 expression was correlated with CD163, indicating a prospective role for CAV1 in adipose inflammatory microenvironment. Unlike wild-type animals, mice lacking TNF-α exhibited reduced levels of CAV1 mRNA/proteins, which were elevated by administering exogenous TNF-α. Mechanistically, TNF-α induces CAV1 gene transcription by mediating NF-kB binding to its two regulatory elements located in the CAV1 proximal regulatory region. The interplay between CAV1 and TNF-α signaling pathway is interesting and has potential as a target for therapeutic interventions in obesity and metabolic syndromes.
ARTICLE | doi:10.20944/preprints202207.0081.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: adolescents; high sensitivity C-reactive protein; Interleukin 6; Leucine-rich α-2 glycoprotein 1; obesity; TNF-α
Online: 6 July 2022 (03:25:10 CEST)
Leucine-rich α-2 glycoprotein1 (LRG1) is a member of the leucine-rich repeat (LRR) family that was implicated in multiple diseases including cancer, aging and heart failure as well as diabetes and obesity. LRG1 plays a key role in diet-induced hepatosteatosis and insulin resistance by mediating the crosstalk between adipocytes and hepatocytes. LRG1 also promotes hepatosteatosis by upregulating de novo lipogenesis in the liver and suppressing fatty acid β oxidation. In this study, we investigated the association of LRG1 with obesity markers including leptin and other adipokines in adolescents (11-14 years; n=425). BMI-for-age classification based on WHO growth charts was used to define obesity. Plasma LRG1 was measured by ELISA while other markers were measured by multiplexing assay. Median (IQR) of LRG1 levels was higher in obese [30 (25, 38) µg/mL] and overweight [30 (24, 39) µg/mL] adolescents, compared to normal-weight participants [27 (22, 35) µg/mL]. The highest tertile of LRG1 had an OR [95%CI] of 2.55 [1.44, 4.53] for obesity. LRG1 was positively correlated to plasma levels of HsCRP (R=0.2), Leptin (R=0.2) and Chemerin (R=0.24) with p<0.001. Additionally, it was positively associated with plasma level of IL6 (R=0.17) and IL10 (R=0.14) but not TNF-α. In conclusion, LRG1 levels are increased in obese kids and associate with increased levels of adipogenic markers. These results suggest the usefulness of LRG1 as an early biomarker for obesity and its related pathologies in adolescents.
ARTICLE | doi:10.20944/preprints202105.0258.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: ANGPTL3-DOCK7; irisin; c-peptide; triglyceride; interleukin 13; lipid metabolism; insulin resistance; Arab population
Online: 12 May 2021 (07:28:31 CEST)
ANGPTL3 is an important regulator of lipid metabolism. Its inhibition in people with hypercholesteremia reduces plasma lipid levels dramatically. Genome-wide association studies have associated ANGPTL3 variants with lipid traits. Irisin, an exercise modulated protein, has been associated with lipid metabolism. Intracellular accumulation of lipids impairs insulin action and contributes to metabolic disorders. In this study, we evaluate the impact of ANGPTL3 variants on levels of irisin and markers associated with lipid metabolism and insulin resistance. ANGPTL3 rs1748197 and rs12130333 variants were genotyped in a cohort of 278 Arab individuals from Kuwait. Levels of irisin and other metabolic markers were measured by ELISA. Significance of association signals was assessed using Bonferroni-corrected P-values and empirical P-values. The study variants were significantly associated with low levels of c-peptide and irisin. Levels of c-peptide and irisin were mediated by interaction between carrier genotypes (GA+AA) at rs1748197 and measures of IL13 and TG, respectively. While levels of c-peptide and IL13 were directly correlated in individuals with reference genotype, they were inversely correlated in individuals with carrier genotype. Irisin correlated positively with TG which is strong in individuals with carrier genotypes. These observations illustrate ANGPTL3 as a potential link connecting lipid metabolism, insulin resistance and cardioprotection.
ARTICLE | doi:10.20944/preprints202104.0655.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: Meteorin-like hormone, irisin, adipomyokines, bone markers, Osteoactivin , Syndecan, OPG, Osteonectin, type 2 diabetes, obesity.
Online: 26 April 2021 (10:57:31 CEST)
The musculoskeletal system consisting of bones and muscles have been recognized as endocrine organs secreting hormones that are involved in regulating metabolic and inflammatory pathways. Obesity and type 2 diabetes (T2D) are associated with several musculoskeletal system complications. We hypothesized that an interaction exists between adipomyokines namely, irisin and METRNL, and various bone markers in individuals with obesity and T2D. A total of 228 individuals were enrolled in this study, including 124 non-diabetic and 104 T2D. A Multiplex assay was used to assess the level of various bone markers namely Osteoactivin, Syndecan, osteoprotegerin (OPG) and osteonectin/SPARC. Our data shows elevated levels of Osteoactivin, Syndecan, OPG and SPARC in T2D as compared to non-T2D individuals (p ≤ 0.05). Using Spearman’s correlation, irisin was positively correlated only with Osteoactivin and OPG (p < 0.05). Similarly, a positive association was observed between METRNL and Osteoactivin (p < 0.05). The strong positive association shown in our study between irisin, METRNL and various bone markers emphasises the strong interaction between these organs. This suggests that a dysregulation in the functional interaction between these molecules could play a possible role in the development of bone and muscle related complications that are associated with obesity and T2D.
ARTICLE | doi:10.20944/preprints202011.0497.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: ONC201; colorectal cancer cells; DDIT3; CHOP; BAK/BAX pathway
Online: 19 November 2020 (08:42:43 CET)
The imipramine ONC201 exerts a novel anti-proliferative activity over a wide spectrum of cancer cell types. ONC201 activates integrated stress response pathway that is associated with induction of Damage Inducible Transcript 3 (DDIT3, also known as C/EBP homologous protein or CHOP). We questioned whether the ONC201/CHOP crosstalk is regulated by diverse signaling pathways in non-metastatic versus metastatic cancer cell lines. Therefore, the Dukes' type B colorectal adenocarcinoma non-metastatic (SW480) and metastatic (LS-174T) cell lines were treated with ONC201. Cell proliferation and apoptosis were evaluated by MTT assay, flow cytometry analysis, gene expression was assessed by Affymetrix microarray, and key regulatory proteins were validated by Western blot assays. Unlike LS-174T cells, SW480 cells were resistant to ONC201 treatment. Gene ontology pathway enrichment analysis of differentially expressed genes revealed substantial differences between LS-174T and SW480 responsiveness to ONC201 treatment. In both cell lines, CHOP expression was upregulated in response to ONC201 treatment, however, its upstream regulatory mechanisms were not identical. Although, PERK, ATF6 and IRE1 ER-stress pathways were found to upregulated CHOP in both cell types, the BAK/BAX pathway was a notable regulator of CHOP in the metastatic LS-174T cells alone. In addition, CHOP RNA splicing profiles were varied between the two cell lines, which was further modified in response to ONC201 treatments. In conclusion, we delineated the signaling mechanisms regulating the expression of CHOP in non-metastatic versus metastatic colorectal cells in response to ONC201 treatment. The observed differences were related to cellular plasticity and metabolic reprogramming.
ARTICLE | doi:10.20944/preprints202007.0327.v1
Subject: Medicine And Pharmacology, Clinical Medicine Keywords: Obstructive sleep apnea; Metabolomics; Triglycerides; Phosphocholines; Ceramides; Apnea Hypopnea Index; Polysomnography; Lipid metabolism; Multilevel Sleep Surgery
Online: 15 July 2020 (09:19:05 CEST)
Background: Obstructive sleep apnea (OSA) is caused by partial or complete obstruction of the upper airways. Corrective surgeries aim at removing obstructions in the nasopharynx, oropharynx, and hypopharynx. OSA is associated with increased risk of various metabolic diseases. Our objective was to evaluate the effect of surgery on the plasma metabolome. Methods: This study included 39 OSA patients who underwent Multilevel Sleep Surgery (MLS). Clinical and anthropometric measures were taken at baseline and 5 months after surgery. Results: The mean Apnea Hypopnea Index (AHI) significantly dropped from 22.0 ± 18.5 events/hour to 8.97 ± 9.57 events/hour (p-Value <0.001). The Epworth’s sleepiness Score (ESS) dropped from 12.8 ± 6.23 to 2.95 ± 2.40 (p-Value <0.001) indicating success of the surgery in treating OSA. Plasma levels of metabolites, phosphocholines (PC) PC.41.5, PC.42.3, ceremide (Cer) Cer.44.0, and triglyceride (TG) TG.53.6, TG.55.6 and TG.56.8 were decreased (p-Value<0.05) whereas lysophosphatidylcholines (LPC) 20.0 and PC.39.3 were increased (p-Value<0.05) after surgery. Conclusion: This study highlights the success of MLS in treating OSA. Treatment of OSA resulted in improvement in metabolic status that was characterized by decreased TG, PCs and Cer metabolites post-surgery indicating that the success of the surgery positively impacted the metabolic status of these patients.
ARTICLE | doi:10.20944/preprints202310.0273.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: NAFLD; SMPD3; Lipotoxicity; HepG2; TNF-α; sphingomyelin pathway; RNA sequencing; Oil Red O staining; fat accumulation; Obesity
Online: 5 October 2023 (09:27:30 CEST)
Background: Non-alcoholic fatty liver disease (NAFLD) is manifested by hepatic steatosis, insulin resistance, hepatocyte death, and systemic inflammation. Obesity induces steatosis and chronic inflammation in the liver. However, the precise mechanism underlying hepatic steatosis in the setting of obesity remains unclear. Here we report studies that address this question. Methods: 14 weeks on high-fat diet (HFD) with high sucrose, C57BL/6 mice revealed a phenotype of liver steatosis. Transcriptional profiling analysis of the liver tissues was performed using RNA sequencing (RNA-seq). Results: Our RNA-seq data revealed 692 differentially expressed genes involved in processes of lipid metabolism, oxidative stress, immune responses, and cell proliferation. Notably, the gene encoding neutral sphingomyelinase SMPD3, was predominantly upregulated in the liver tissues of the mice displaying a phenotype of steatosis. Moreover, nSMase2 activity was elevated in these tissues of the liver. Pharmacological and genetic inhibition of nSMase2 prevented intracellular lipid accumulation and TNFα-induced inflammation in in-vitro HepG2-steatosis cellular model. Furthermore, nSMase2 inhibition ameliorates oxidative damage by rescuing PPARα and prevent cell death associated with high glucose/oleic acid-induced fat accumulation in HepG2 cells. Conclusions: Collectively, our findings highlight the prominent role of nSMase2 in hepatic steatosis which could serve as a potential therapeutic target for NAFLD and other hepatic steatosis-linked disorders.