Mechanisms of Insulin Action and Insulin Resistance

Physiological Reviews, Journal Year: 2018, Volume and Issue: 98(4), P. 2133 - 2223

Published: Aug. 1, 2018

The 1921 discovery of insulin was a Big Bang from which vast and expanding universe research into action resistance has issued. In the intervening century, some discoveries have matured, coalescing solid fertile ground for clinical application; others remain incompletely investigated scientifically controversial. Here, we attempt to synthesize this work guide further mechanistic investigation inform development novel therapies type 2 diabetes (T2D). rational such necessitates detailed knowledge one key pathophysiological processes involved in T2D: resistance. Understanding resistance, turn, requires normal action. review, both physiology pathophysiology are described, focusing on three target tissues: skeletal muscle, liver, white adipose tissue. We aim develop an integrated physiological perspective, placing intricate signaling effectors that carry out cell-autonomous response context tissue-specific functions generate coordinated organismal response. First, section II, effects direct, tissue reviewed, beginning at receptor working downstream. Section III considers critical underappreciated role crosstalk whole body action, especially essential interaction between lipolysis hepatic gluconeogenesis. is then described IV. Special attention given pathways become resistant setting chronic overnutrition, alternative explanation phenomenon ‟selective resistanceˮ presented. Sections V, VI, VII critically examine evidence against several putative mediators V reviews linking bioactive lipids diacylglycerol, ceramide, acylcarnitine resistance; VI impact nutrient stresses endoplasmic reticulum mitochondria discusses non-cell autonomous factors proposed induce including inflammatory mediators, branched-chain amino acids, adipokines, hepatokines. Finally, VIII, propose model links these final common metabolite-driven gluconeogenesis ectopic lipid accumulation.

Language: Английский

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AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease

Hepatology, Journal Year: 2023, Volume and Issue: 77(5), P. 1797 - 1835

Published: Feb. 2, 2023

PREAMBLE The study of NAFLD has intensified significantly, with more than 1400 publications since 2018, when the last American Association for Study Liver Diseases (AASLD) Guidance document was published.1 This new AASLD reflects many advances in field pertinent to any practitioner caring patients and emphasizes noninvasive risk stratification therapeutics. A separate guideline focused on management context diabetes been written jointly by Clinical Endocrinology AASLD.2 Given significant growth pediatric NAFLD, it will not be covered here allow a robust discussion diagnosis upcoming Pediatric Guidance. "Guidance" differs from "Guideline" that is bound Grading Recommendations, Assessment Development Evaluation system. Thus, actionable statements rather formal recommendations are provided herein. highest available level evidence used develop these statements, and, where high-level available, expert opinion guidance inform clinical practice. Key points highlight important concepts relevant understanding disease its management. most profound practice biomarkers Biomarkers tests (NITs) can clinically either exclude advanced diseases or identify those high probability cirrhosis.3,4 NIT "cut points" vary populations studied, underlying severity, setting. Those proposed this meant aid decision-making clinic interpreted isolation. Identifying "at-risk" NASH (biopsy-proven stage 2 higher fibrosis) recent area interest. Although definitive staging remain linked histology, tools now assess likelihood fibrosis, predict progression decompensation, make decisions, some degree, response treatment. There an ongoing debate over nomenclature fatty liver disease, which had finalized at time published. At culmination rigorous consensus process, intended change advance without negative impact awareness, trial endpoints, drug development/approval process. Furthermore, should emergence newly recognized subtypes address heterogeneity, including role alcohol, therapy. Input central all stages process ensure minimization nomenclature-related stigma. DEFINITIONS overarching term includes grades refers population ≥5% hepatocytes display macrovesicular steatosis absence readily identified alternative cause (eg, medications, starvation, monogenic disorders) individuals who drink little no alcohol (defined as < 20 g/d women <30 men). spectrum NAFL, characterized hepatic may accompanied mild inflammation, NASH, additionally presence inflammation cellular injury (ballooning), finally cirrhosis, bands fibrous septa leading formation cirrhotic nodules, earlier features longer fully appreciated biopsy. UPDATE ON EPIDEMIOLOGY AND NATURAL HISTORY prevalence rising worldwide parallel increases obesity metabolic comorbid (insulin resistance, dyslipidemia, obesity, hypertension).5,6 adults estimated 25%–30% general population7–9 varies setting, race/ethnicity, geographic region studied but often remains undiagnosed.10–14 associated economic burden attributable substantial.15–17 challenging determine certainty; however, 14% asymptomatic undergoing colon cancer screening.14 also highlights publication prior prospective study,18 fibrosis (stage increased >2-fold. supported projected rise 2030, defined bridging (F3) compensated cirrhosis (F4), increase disproportionately, mirroring doubling NASH.5,19 As such, incidence HCC, death related likewise expected 2- 3-fold 2030.5 further, NASH-related already indication transplantation >65 years age par overall.20–22 Natural history Data meta-analyses pooled studies demonstrate steatohepatitis primary predictors progression.23–25 collinearity between induces makes independent contribution adverse outcomes multivariable analyses.26,27 determinant outcomes, liver-related morbidity mortality nonhepatic malignancy observed even initial biopsy.25 Nevertheless, least (F2), referred have demonstrably mortality.24,28 Fibrosis influenced factors such severity genomic profile, environmental factors. meta-analysis placebo-treated 35 trials found minimal progression, suggesting nonpharmacologic (frequent visits/monitoring, dietary lifestyle counseling, changes) reduce progression.29 An cohorts longitudinal paired biopsies30 demonstrated rate one per 7 versus 14 NAFL.30 determined biopsy noninvasively, because changes require biannual screening HCC well varices monitoring signs symptoms decompensation.31,32 Among decompensation ranges 3% 20% year.12,33–35 common causes overall cardiovascular (CVD) malignancy, followed disease. amount histologically strongly development death.24,26,36,37 Bridging exponentially greater fibrosis.23,24,35 In 1773 patients, all-cause 0–2 0.32 100 person-years, compared 0.89 person-years 1.76 cirrhosis. After correcting multiple factors, (HR, 6.8; 95% CI, 2.2–21.3).35 Cirrhosis regression 6-fold reduction events trials.38Key points: Patients F2–4 considered NASH. rates depending baseline genetic, individual environmental, determinants. CVD malignancies fibrosis; predominates fibrosis. MOLECULAR CELLULAR PATHOGENESIS NAFL substantially govern supply disposition acids, diacylglycerols, ceramides, cholesterol, phospholipids, other intrahepatic lipids. Energy oversupply limited adipose tissue expansion contribute insulin resistance disease.39 When energy intake exceeds needs disposal capacity, carbohydrates, form sugars fructose, sucrose, glucose), drive accumulation fat de novo lipogenesis (DNL).40,41 substantial interindividual heterogeneity DNL among NAFLD.42,43 addition, type consumed plays saturated unsaturated consumption (Figure 1).44–46FIGURE 1: Pathogenic drivers therapeutic targets. Overview major mechanisms lead phenotype consequences, leveraged therapeutically. Not shown areas genetic polymorphisms play modifying types fats [saturated vs. polyunsaturated acid (PUFA)], gut microbiome, uric acid, periodic hypoxia (sleep apnea) influence pathways. driver adipocytes their ability store triglyceride inducing cell stress exceeded, activates inflammatory pathways resistance. Understanding facilitates rational therapies Specific sites intervention might prevent resolve include interventions modulate food portion sizes, bariatric surgery, satiety regulators), exercise, thermogenesis), improve adipocyte sensitivity [eg, peroxisome proliferator-activated receptor (PPAR)γ ligands], impair acetyl-coenzyme carboxylase synthase inhibitors), oxidative metabolism (PPARα ligands thyroid hormone beta agonists), attenuate death, fibrogenesis. Therapeutic agents affecting throughout body potential beneficial effects peptide analogs fibroblast factor-19, factor-21, glucagon-like peptide-1, gastric inhibitory peptide, glucagon) nuclear drugs target PPARα, PPARδ, PPARγ, β, farnesoid X receptor. Abbreviations: ER, endoplasmic reticulum; CVD, disease.Insulin nearly universal present liver, tissue, muscle.47 Adipose release free acids (lipolysis) fasting state48 worsens NASH.39,47,49 Important frequency intensity activation brown energy-consuming thermogenic phenotype, counterregulatory diminish reductions calorie intake.39,50 desire engage regular exercise personal, community, corporate, societal, legislative thus roles contributing pathophysiology impeded diagnostic therapeutics.51 driven substrate overload heavily impacting hepatocyte lipid handling.43 Genetic I148M polymorphism PNPLA3 impairs lipolysis droplets,52 proteins transmembrane 6 superfamily member (TM6SF2), cholesterol metabolism,53 MBOAT7, influences phospholipid metabolism.54 Recently, loss-of-function variants HSD17B13, gene encodes enzyme localizes droplets hepatocytes, protection against progressive HCC.55 Rare mutations CIDEB, protein needed DNL,56 protective.57 host additional review beyond scope guidance, activity progression.49,58–63 Additional production, exposure products derived perhaps low magnesium levels, phenotype.64–69 Transcriptomic profiling large further our progression.70,71 lipotoxic recruitment resident macrophages, contributes hepatocellular stellate part complex interplay types.60,72,73 markers consistent finding pathogenesis humans uncertain.74Key Fundamental elements imbalance nutrient delivery utilization coupled dysfunction. Interindividual differences dietary, behavioral, course. Systemic particularly stemming dysfunctional progression. Insulin promotes COMORBID CONDITIONS ASSOCIATED WITH closely precedes abnormalities hypertension).47,61,75–77 Having several confers histological mortality.8,47,78–81 association comorbidities reflect bidirectional interactions endocrine organs pancreas, muscle) through secretion hepatokines regulate metabolism, action, glucose metabolism,82–88 adipokines, myokines.39,89,90 Obesity progression.91–93 Body distribution contributory (Table 1). Android distribution, truncal subcutaneous visceral irrespective mass index (BMI).94–99 contrast, gynoid predominantly hips buttocks, appears protective NAFLD.39,100 Visceral fat, metabolically active mediates majority risk.101–105 becomes stressed, dysfunctional, inflamed, signaling progressively impaired, promoting inappropriate inflammation.47,106,107 TABLE 1 - Initial evaluation patient History Weight history; medical comorbidities; current medications; family T2DM, cirrhosis; OSA; use, amount, pattern duration Physical examination android gynoid, lipodystrophic), dorsal-cervical pad, acanthosis nigricans), firm splenomegaly, prominent abdominal veins, ascites, gynecomastia, spider angiomata, palmar erythema) Laboratory Hepatic panel, CBC platelets, plasma glycated hemoglobin (A1c), creatinine urine microalbumin ratio, hepatitis C if previously screened. Consider appropriate steatosis/steatohepatitis (). elevated chemistries present: autoimmune serologies, transferrin saturation, ceruloplasmin, alpha-1 antitrypsin genotype, CBC, complete blood count; OSA, obstructive sleep apnea; mellitus. Type mellitus (T2DM) T2DM impactful factor HCC.108–111 pathogenic both surprising (ranging 30% 75%)10,112,113 developing fibrosis.93,114–117 T2DM. there length biases, underscore strong relationship NAFLD. epidemiological studies. Early course, sensitivity,47 overt diabetes. 5-fold incident diabetes,75,118–121 therefore, screened progresses, so does failure, making manage.107 glycemic control NAFLD/NASH controversial, small showing poor fibrosis,68,122 whereas corroborated finding.116,117,123 described diabetes, much lower coexistent BMI).124,125 Hypertension commonly hypertension across spectrum, 6.5 early 14.5 cirrhosis.35 clearly additive respect NASH126,127 progression.30 Whether mechanistically inverse, manifestations drivers, established.128,129 Dyslipidemia twice likely exhibit NAFLD,120 serum subfractions atherogenic NAFLD.130,131 resolution improved HDL levels favorably lipoprotein subfractions, although unclear what extent mechanism intervention.132–134 progress they continue coronary artery disease135 despite normalization lipids lipoproteins due synthetic failure.130,136 Management dyslipidemia use moderate-intensity high-intensity statins first-line therapy based atherosclerotic scores. Combination hypolipemic agents, ezetimibe, PCSK-9 inhibitors, inclisiran, bempedoic fibrates, omega 3 icosapent ethyl, monotherapy statin achieve goals. Statins safe demonstrable mortality.137–140 However, practice, underused extensive data demonstrating safety, cirrhosis.141–144 future risk, confirmatory needed.138 safely decompensated statin-induced population,144 caution warranted. transplantation, careful monitoring.136 severely triglycerides >500 mg/dL), combination fibrates prescription grade omega-3 pancreatitis. Fibrates concentrations ≥200 mg/dL HDL-C <40 mg/dL. high-risk individuals, ethyl indicated adjunct risk. Pioglitazone optimization concomitant benefits profile. Caution taken myopathy. Obstructive apnea (OSA) OSA NAFLD,145 suggest histology.146–151 Intermittent hypoxia, critical consequence mitochondrial dysfunction,145 dysregulation metabolism,152,153 worse resistance,154–156 DNL.157 overweight obese polysomnography NAFLD158; independently drives unclear. exists heart arrhythmias, atrial fibrillation.159–167 Perturbed endothelial function, higher-risk nature lesions, impaired ischemic compensatory support link CVD.130,168–170 prospectively observational cohort, cardiac same stages; number relatively low.35 Optimizing goal reducing improving NAFLD.36,171,172 Aggressively treating conditions hypertension, hyperglycemia smoking cessation recommended decrease risk.173 Chronic kidney (CKD) cross-sectional (n=28,000 individuals) 2-fold CKD.174 overall, specifically, microvascular diabetic complications, especially CKD.175,176 Recently published CRN CKD stages.35 determined.Guidance statements: 1. 2. Limited exist safety efficacy could 3. Hypertriglyceridemia managed supplementation fibrates. 4. 5. Prevalence Death thus, adherence age-appropriate survival. INITIAL EVALUATION OF PATIENT incidentally noted imaging chemistries. It note normal values laboratories true alanine aminotransferase (ALT) 29 33 U/L men 19 25 women.177 comorbidities, assessment intake, exclusion physical profile atypical comorbidities) additional/alternate etiologies, less excluded 2). fibrosing isolation explain exaggerated specific contexts 2).178 Several exacerbate during 3). gene-based currently familial aggregation supports gene-environment fibrosis.209,210 consider testing Condition scenario Diagnostic test Treatment Hypobetalipoproteinemia Low LDL, triglycerides, malabsorption ApoB level, (MTTP, PCSK-9) Low-fat diet, fat-soluble vitamin LAL deficiency Markedly LDL-C HDL-C, xanthelasma, hypersplenism, young age, predominately microvesicular Enzyme assay, replacement Nutrient carnitine, choline) Anorexia, short bowel, bypass surgeries Supplementation Wilson Younger neuropsychiatric symptoms, alkaline phosphatase, ceruloplasmin 24-h copper; quantitative copper Chelation Celiac Iron deficiency, pain, bloating, D bone loss, diarrhea, dermatitis herpetiformis Tissue transglutaminase IgA, duodenal Gluten-free diet ApoB, apolipoprotein B; high-density cholesterol; immunoglobulin A; LAL, lysosomal lipase; LDL-C, LDL cholesterol. Drugs mechanistic links Drug Mechanism Histological References Amiodarone Promotion DNL, impairment β-oxidation steatohepatitis, phospholipidosis, 179–184 5-FU Accumulation catabolites capacity metabolize 185–188 Irinotecan Induces dysfunction, autophagy Steatohepatitis 189–194 Tamoxifen Estrogen modulator, promotion β-oxidation. *May Steatosis 195–203 Methotrexate Mitochondrial (inhibits electron transport chain), canals Hering Steatosis, 204–206 Corticosteroids Exacerbation

Language: Английский

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Molecular phenomics and metagenomics of hepatic steatosis in non-diabetic obese women

Nature Medicine, Journal Year: 2018, Volume and Issue: 24(7), P. 1070 - 1080

Published: June 25, 2018

Language: Английский

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Cellular and Molecular Mechanisms of Metformin Action

Endocrine Reviews, Journal Year: 2020, Volume and Issue: 42(1), P. 77 - 96

Published: Sept. 8, 2020

Metformin is a first-line therapy for the treatment of type 2 diabetes, due to its robust glucose-lowering effects, well-established safety profile, and relatively low cost. While metformin has been shown have pleotropic effects on glucose metabolism, there general consensus that major effect in patients with diabetes mostly mediated through inhibition hepatic gluconeogenesis. However, despite decades research, mechanism by which inhibits this process still highly debated. A key reason these discrepant likely inconsistency dosage across studies. Widely studied mechanisms action, such as complex I leading AMPK activation, only observed context supra-pharmacological (>1 mM) concentrations, do not occur clinical setting. Thus, challenged recent years new proposed. Based observation alters cellular redox balance, redox-dependent action described several groups. Recent studies clinically relevant (50-100 μM) concentrations inhibit gluconeogenesis substrate-selective manner both vitro vivo, supporting action. Here, we review current literature regarding metformin's molecular

Language: Английский

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Trends in insulin resistance: insights into mechanisms and therapeutic strategy

Signal Transduction and Targeted Therapy, Journal Year: 2022, Volume and Issue: 7(1)

Published: July 6, 2022

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into medically manageable chronic condition. Insulin is key peptide hormone and mediates the systemic glucose metabolism in different tissues. resistance (IR) disordered biological response for stimulation through disruption molecular pathways target Acquired conditions genetic factors have been implicated IR. Recent biochemical studies suggest that dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids toxic lipid metabolites promote IR other associated with several groups abnormal syndromes include obesity, diabetes, dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), abnormalities. Although no medication specifically approved treat IR, we summarized lifestyle changes pharmacological medications used as efficient intervention improve sensitivity. Ultimately, systematic discussion complex mechanism will help identify potential new targets closely

Language: Английский

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An Integrated Understanding of the Rapid Metabolic Benefits of a Carbohydrate-Restricted Diet on Hepatic Steatosis in Humans

Cell Metabolism, Journal Year: 2018, Volume and Issue: 27(3), P. 559 - 571.e5

Published: Feb. 15, 2018

Language: Английский

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Unraveling the Regulation of Hepatic Gluconeogenesis

Frontiers in Endocrinology, Journal Year: 2019, Volume and Issue: 9

Published: Jan. 23, 2019

Hepatic gluconeogenesis, de novo glucose synthesis from available precursors, plays a crucial role in maintaining homeostasis to meet energy demands during the prolonged starvation animals. The abnormally increased rate of hepatic gluconeogenesis contributes hyperglycemia diabetes. Gluconeogenesis is regulated on multiple levels, such as hormonal secretion, gene transcription and posttranslational modification. We review here molecular mechanisms underlying transcriptional regulation response nutritional changes. nutrient state determines hormone release, which instigates signaling cascades liver modulate activities various factors through post-translational modifications phosphorylation, methylation acetylation. AMP-activated protein kinase (AMPK) can mediate some factors, however its remains uncertain. Metformin, primary hypoglycemic agent type 2 diabetes, ameliorates predominantly suppression gluconeogenesis. Several have been proposed be metformin's mode action.

Language: Английский

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Gluconeogenesis in Cancer: Function and Regulation of PEPCK, FBPase, and G6Pase

Trends in cancer, Journal Year: 2018, Volume and Issue: 5(1), P. 30 - 45

Published: Dec. 20, 2018

Language: Английский

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AMPK signaling in diabetes mellitus, insulin resistance and diabetic complications: A pre-clinical and clinical investigation

Biomedicine & Pharmacotherapy, Journal Year: 2021, Volume and Issue: 146, P. 112563 - 112563

Published: Dec. 29, 2021

Diabetes mellitus (DM) is considered as a main challenge in both developing and developed countries, lifestyle has changed its management seems to be vital. Type I type II diabetes are the kinds they result hyperglycemia patients related complications. The gene expression alteration can lead development of DM AMP-activated protein kinase (AMPK) an energy sensor with aberrant various diseases including cancer, cardiovascular DM. present review focuses on understanding AMPK role Inducing signaling promotes glucose that importance for ameliorating hyperglycemia. Further investigation reveals enhancing insulin sensitivity treatment diabetic patients. Furthermore, upregulation inhibits stress cell death β cells preventing development. clinical studies have shown improving complications such brain disorders. improve neuropathy, nephropathy, liver reproductive alterations occurring during For exerting protective impacts, interacts other molecular pathways PGC-1α, PI3K/Akt, NOX4 NF-κB among others. Therefore, providing therapeutics based targeting beneficial amelioration

Language: Английский

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Regulation of glucose and lipid metabolism in health and disease

Science China Life Sciences, Journal Year: 2019, Volume and Issue: 62(11), P. 1420 - 1458

Published: Oct. 31, 2019

Language: Английский

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