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PURPOSE: Vascular and immune dysfunction are hallmarks of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections and coronavirus disease 2019 (COVID-19). Although our understanding of the pathogenesis of COVID-19 has rapidly evolved, much of the focus has been on the immune mechanisms underlying COVID-19. In addition to immune dysfunction, vascular injury is also associated with COVID-19 and is a major driver of clinical deterioration in SARS-CoV-2 infections. The glycocalyx (GAC), a sugar-based shell that surrounds all mammalian cells, is an important regulator of vascular and immune responses. In sepsis, vascular dysfunction contributes to acute respiratory distress syndrome (ARDS) by altering vessel integrity, promoting thrombosis, and accelerating inflammation, all of which are also present in COVID-19. Observational studies in sepsis have found an association between levels of circulating GAC degradation products with both organ dysfunction and mortality. Although vascular dysfunction is a hallmark of COVID-19, it remains unclear whether GAC disruption occurs in COVID-19 and if GAC disruption contributes to the clinical progression of COVID-19. METHODS: In this prospective cohort study, we measured the GAC components syndecan-1 (SDC1) and hyaluronan (Hyal) along with inflammatory cytokines in 12 hospitalized COVID-19 patients and 8 healthy controls (HC). RESULTS: In agreement with other studies, we found that inflammatory cytokines are elevated in hospitalized COVID-19 patients compared with HC [median (IQR), all units picograms per milliliter: IL-6 4.65 (3.32-9.16) vs 0.69 (0.55-0.89), p < 0.001; TNFα 4.49 (1.87-8.03) vs 0.04 (0.04-0.84), p < 0.001]. Additionally, we found that the GAC components SDC1 and Hyal are also elevated in COVID-19 patients [median (IQR), all units picograms per milliliter: SDC1: 247.37 (101.43-458.26) vs 84.8 (52.88-123.59), p = 0.036; Hyal: 26.41 (16.4-35.1) vs 3.01 (1.66-4.61), p < 0.001]. CONCLUSION: We propose that GAC markers offer insights into the pathobiology of COVID-19, potentially guide therapeutic approaches, and could aid in early risk stratification that is particularly beneficial in phasic diseases such as COVID-19.
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COVID-19 , Sepse , Animais , Humanos , SARS-CoV-2 , Estudos Prospectivos , Glicocálix , Citocinas , MamíferosRESUMO
OBJECTIVE: The goal of this investigation was to evaluate circulating and skeletal muscle inflammatory biomarkers between maintenance hemodialysis (MHD) and demographic-matched control subjects (CON) before and after ingestion of a protein-rich meal. DESIGN AND METHODS: CON (n = 8; 50 ± 2 years; 31 ± 1 kg/m2) and MHD patients (n = 8; 56 ± 5 years; 32 ± 2 kg/m2) underwent a basal blood draw and muscle biopsy and serial blood draws after the ingestion of a mixed meal on a nondialysis day. Plasma advanced glycation end products (AGEs) and markers of oxidation were assessed via liquid chromatography-tandem mass spectrometry before and after the meal (+240 min). Circulating inflammatory cytokines and soluble receptors for AGE (sRAGE) isoforms (endogenous secretory RAGEs and cleaved RAGEs) were determined before and after the meal (+240 min). Basal muscle was probed for inflammatory cytokines and protein expression of related signaling components (RAGE, Toll-like receptor 4, oligosaccharyltransferase subunit 48, TIR-domain-containing adapter-inducing interferon-ß, total IκBα, and pIκBα). RESULTS: Basal circulating AGEs were 7- to 343-fold higher (P < .001) in MHD than those in CON, but only MG-H1 increased in CON after the meal (P < .001). There was a group effect (MHD > CON) for total sRAGEs (P = .02) and endogenous secretory RAGEs (P < .001) and a trend for cleaved RAGEs (P=.09), with no meal effect. In addition, there was a group effect (MHD < CON; P < .05) for circulating fractalkine, interleukin (IL)10, IL17A, and IL1ß and a trend (P < .10) for IL6 and macrophage inflammatory protein 1 alpha, whereas tumor necrosis factor alpha was higher in MHD (P < .001). In muscle, Toll-like receptor 4 (P = .03), TIR-domain-containing adapter-inducing interferon-ß (P = .002), and oligosaccharyltransferase subunit 48 (P = .02) expression was lower in MHD than that in CON, whereas IL6 was higher (P = .01) and IL8 (P = .08) tended to be higher in MHD. CONCLUSION: Overall, MHD exhibited an exaggerated, circulating, and skeletal muscle inflammatory biomarker environment, and the meal did not appreciably affect the inflammatory status.
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Produtos Finais de Glicação Avançada , Receptor 4 Toll-Like , Humanos , Produtos Finais de Glicação Avançada/metabolismo , Interleucina-6 , Biomarcadores , Interferon beta , Ingestão de AlimentosRESUMO
PURPOSE: Acute heart failure (AHF) syndromes manifest increased inflammation and vascular dysfunction; however, mechanisms that integrate the two in AHF remain largely unknown. The glycocalyx (GAC) is a sugar-based shell that envelops all mammalian cells. Much GAC research has focused on its role in vascular responses, with comparatively little known about how the GAC regulates immune cell function. METHODS: In this study, we sought to determine if GAC degradation products are elevated in AHF patients, how these degradation products relate to circulating inflammatory mediators, and whether the monocyte GAC (mGAC) itself modulates monocyte activation. Inflammatory markers and GAC degradation products were profiled using ELISAs. Flow cytometry was used to assess the mGAC and RNA-seq was employed to understand the role of the mGAC in regulating inflammatory activation programs. RESULTS: In a cohort of hospitalized AHF patients (n = 17), we found that (1) the GAC degradation product heparan sulfate (HS) was elevated compared with age-matched controls (4396 and 2903 ng/mL; p = 0.01) and that (2) HS and soluble CD14 (a marker of monocyte activation) levels were closely related (Pearson's r = 0.65; p = 0.002). Mechanistically, Toll-like receptor (TLR) activation of human monocytes results in GAC remodeling and a decrease in the mGAC (71% compared with no treatment; p = 0.0007). Additionally, we found that ex vivo enzymatic removal of HS and disruption of the mGAC triggers human monocyte activation and amplifies monocyte inflammatory responses. Specifically, using RNA-seq, we found that enzymatic degradation of the mGAC increases transcription of inflammatory (IL6, CCL3) and vascular (tissue factor/F3) mediators. CONCLUSION: These studies indicate that the mGAC is dynamically remodeled during monocyte activation and that mGAC remodeling itself may contribute to the heightened inflammation associated with AHF.
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Chemokines and their receptors play important roles in vascular homeostasis, development, and angiogenesis. Little is known regarding the molecular signaling mechanisms activated by CCL28 chemokine via its primary receptor CCR10 in endothelial cells (ECs). Here, we test the hypothesis that CCL28/CCR10 signaling plays an important role in regulating skin wound angiogenesis through endothelial nitric oxide synthase (eNOS)-dependent Src, PI3K, and MAPK signaling. We observed nitric oxide (NO) production in human primary ECs stimulated with exogenous CCL28, which also induced direct binding of CCR10 and eNOS resulting in inhibition of eNOS activity. Knockdown of CCR10 with siRNA lead to reduced eNOS expression and tube formation suggesting the involvement of CCR10 in EC angiogenesis. Based on this interaction, we engineered a myristoylated 7 amino acid CCR10-binding domain (Myr-CBD7) peptide and showed that this can block eNOS interaction with CCR10, but not with calmodulin, resulting in upregulation of eNOS activity. Importantly, topical administration of Myr-CBD7 peptide on mouse dermal wounds not only blocked CCR10-eNOS interaction, but also enhanced expression of eNOS, CD31, and IL-4 with reduction of CCL28 and IL-6 levels associated with improved wound healing. These results point to a potential therapeutic strategy to upregulate NO bioavailability, enhance angiogenesis, and improve wound healing by disrupting CCL28-activated CCR10-eNOS interaction.
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Quimiocinas CC/metabolismo , Neovascularização Fisiológica , Óxido Nítrico Sintase Tipo III/metabolismo , Receptores CCR10/metabolismo , Pele/fisiopatologia , Cicatrização , Animais , Quimiocinas CC/genética , Células Endoteliais da Veia Umbilical Humana , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase Tipo III/genética , Receptores CCR10/genética , Pele/lesõesRESUMO
PURPOSE: Aerobic (AE) and resistance (RE) exercise elicit unique adaptations in skeletal muscle. The purpose here was to compare the post-exercise response of mTOR signaling and select autophagy markers in skeletal muscle to acute AE and RE. METHODS: In a randomized, cross-over design, six untrained men (27 ± 3 years) completed acute AE (40 min cycling, 70% HRmax) and RE (8 sets, 10 repetitions, 65% 1RM). Muscle biopsies were taken at baseline, and at 1 h and 4 h following each exercise. Western blot analyses were performed to examine total and phosphorylated protein levels. Upstream regulator analyses of skeletal muscle transcriptomics were performed to discern the predicted activation states of mTOR and FOXO3. RESULTS: Compared to AE, acute RE resulted in greater phosphorylation (P < 0.05) of mTORSer2448 at 4 h, S6K1Thr389 at 1 h, and 4E- BP1Thr37/46 during the post-exercise period. However, both AE and RE increased mTORSer2448 and S6K1Thr389 phosphorylation at 4 h (P < 0.05). Upstream regulator analyses revealed the activation state of mTOR was increased for both AE (z score, 2.617) and RE (z score, 2.789). No changes in LC3BI protein were observed following AE or RE (P > 0.05), however, LC3BII protein was decreased after both AE and RE at 1 h and 4 h (P < 0.05). p62 protein content was also decreased at 4 h following AE and RE (P < 0.05). CONCLUSION: Both acute AE and RE stimulate mTOR signaling and similarly impact select markers of autophagy. These findings indicate the early adaptive response of untrained human skeletal muscle to divergent exercise modes is not likely mediated through large differences in mTOR signaling or autophagy.
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Autofagia/fisiologia , Exercício Físico/fisiologia , Proteínas Musculares/metabolismo , Músculo Esquelético/fisiologia , Serina-Treonina Quinases TOR/metabolismo , Adaptação Fisiológica/fisiologia , Adulto , Humanos , Masculino , Treinamento Resistido/métodosRESUMO
Type 2 diabetes mellitus (T2DM) is a risk factor for the development of late-onset Alzheimer's disease (AD). However, the mechanism underlying the development of late-onset AD is largely unknown. Here we show that levels of the endothelial-enriched protein caveolin-1 (Cav-1) are reduced in the brains of T2DM patients compared with healthy aging, and inversely correlated with levels of ß-amyloid (Aß). Depletion of Cav-1 is recapitulated in the brains of db/db (Leprdb ) diabetic mice and corresponds with recognition memory deficits as well as the upregulation of amyloid precursor protein (APP), BACE-1, a trending increase in ß-amyloid Aß42/40 ratio and hyperphosphorylated tau (p-tau) species. Importantly, we show that restoration of Cav-1 levels in the brains of male db/db mice using adenovirus overexpressing Cav-1 (AAV-Cav-1) rescues learning and memory deficits and reduces pathology (i.e., APP, BACE-1 and p-tau levels). Knocking down Cav-1 using shRNA in HEK cells expressing the familial AD-linked APPswe mutant variant upregulates APP, APP carboxyl terminal fragments, and Aß levels. In turn, rescue of Cav-1 levels restores APP metabolism. Together, these results suggest that Cav-1 regulates APP metabolism, and that depletion of Cav-1 in T2DM promotes the amyloidogenic processing of APP and hyperphosphorylation of tau. This may suggest that depletion of Cav-1 in T2DM underlies, at least in part, the development of AD and imply that restoration of Cav-1 may be a therapeutic target for diabetic-associated sporadic AD.SIGNIFICANCE STATEMENT More than 95% of the Alzheimer's patients have the sporadic late-onset form (LOAD). The cause for late-onset Alzheimer's disease is unknown. Patients with Type 2 diabetes mellitus have considerably higher incidence of cognitive decline and AD compared with the general population, suggesting a common mechanism. Here we show that the expression of caveolin-1 (Cav-1) is reduced in the brain in Type 2 diabetes mellitus. In turn, reduced Cav-1 levels induce AD-associated neuropathology and learning and memory deficits. Restoration of Cav-1 levels rescues these deficits. This study unravels signals underlying LOAD and suggests that restoration of Cav-1 may be an effective therapeutic target.
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Doença de Alzheimer/metabolismo , Encéfalo/patologia , Caveolina 1/genética , Diabetes Mellitus Tipo 2/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/genética , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Encéfalo/metabolismo , Caveolina 1/metabolismo , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/patologia , Modelos Animais de Doenças , Masculino , Camundongos , FosforilaçãoRESUMO
BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive hepatic fat accumulation. Increased hepatic saturated fats and decreased hepatic polyunsaturated fats may be particularly lipotoxic, contributing to metabolic dysfunction. We compared hepatic lipid subspecies in adults with and without NAFLD, and examined links with hallmark metabolic and clinical characteristics of NAFLD. METHODS AND RESULTS: Nineteen adults with NAFLD (total hepatic fat:18.8 ± 0.1%) were compared to sixteen adults without NAFLD (total hepatic fat: 2.1 ± 0.01%). 1H-MRS was used to assess hepatic lipid subspecies. Methyl, allylic, methylene, and diallylic proton peaks were measured. Saturation, unsaturation, and polyunsaturation indices were calculated. Whole-body phenotyping in a subset of participants included insulin sensitivity (40 mU/m2 hyperinsulinemic-euglycemic clamps), CT-measured abdominal adipose tissue depots, exercise capacity, and serum lipid profiles. Participants with NAFLD exhibited more saturated and less unsaturated hepatic fat, accompanied by increased insulin resistance, total and visceral adiposity, triglycerides, and reduced exercise capacity compared to controls (all P < 0.05). All proton lipid peaks were related to insulin resistance and hypertriglyceridemia (P < 0.05). CONCLUSION: Participants with NAFLD preferentially stored excess hepatic lipids as saturated fat, at the expense of unsaturated fat, compared to controls. This hepatic lipid profile was accompanied by an unhealthy metabolic phenotype.
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Dislipidemias/diagnóstico , Metabolismo dos Lipídeos , Lipidômica/métodos , Fígado/metabolismo , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Espectroscopia de Prótons por Ressonância Magnética , Adulto , Idoso , Biomarcadores/metabolismo , Estudos de Casos e Controles , Estudos Transversais , Dislipidemias/metabolismo , Dislipidemias/fisiopatologia , Tolerância ao Exercício , Feminino , Humanos , Resistência à Insulina , Fígado/fisiopatologia , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Obesidade Abdominal , Fenótipo , Valor Preditivo dos TestesRESUMO
Skeletal muscle insulin resistance is a hallmark of Type 2 diabetes (T2DM) and may be exacerbated by protein modifications by methylglyoxal (MG), known as dicarbonyl stress. The glyoxalase enzyme system composed of glyoxalase 1/2 (GLO1/GLO2) is the natural defense against dicarbonyl stress, yet its protein expression, activity, and regulation remain largely unexplored in skeletal muscle. Therefore, this study investigated dicarbonyl stress and the glyoxalase enzyme system in the skeletal muscle of subjects with T2DM (age: 56 ± 5 yr.; BMI: 32 ± 2 kg/m2) compared with lean healthy control subjects (LHC; age: 27 ± 1 yr.; BMI: 22 ± 1 kg/m2). Skeletal muscle biopsies obtained from the vastus lateralis at basal and insulin-stimulated states of the hyperinsulinemic (40 mU·m-2·min-1)-euglycemic (5 mM) clamp were analyzed for proteins related to dicarbonyl stress and glyoxalase biology. At baseline, T2DM had increased carbonyl stress and lower GLO1 protein expression (-78.8%), which inversely correlated with BMI, percent body fat, and HOMA-IR, while positively correlating with clamp-derived glucose disposal rates. T2DM also had lower NRF2 protein expression (-31.6%), which is a positive regulator of GLO1, while Keap1 protein expression, a negative regulator of GLO1, was elevated (207%). Additionally, insulin stimulation during the clamp had a differential effect on NRF2, Keap1, and MG-modified protein expression. These data suggest that dicarbonyl stress and the glyoxalase enzyme system are dysregulated in T2DM skeletal muscle and may underlie skeletal muscle insulin resistance. Whether these phenotypic differences contribute to the development of T2DM warrants further investigation.
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Diabetes Mellitus Tipo 2/enzimologia , Resistência à Insulina , Lactoilglutationa Liase/metabolismo , Carbonilação Proteica , Músculo Quadríceps/enzimologia , Adulto , Aldeído Redutase/metabolismo , Glicemia/metabolismo , Estudos de Casos e Controles , Feminino , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Humanos , Insulina/sangue , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Masculino , Pessoa de Meia-Idade , Fator 2 Relacionado a NF-E2/metabolismo , Triose-Fosfato Isomerase/metabolismoRESUMO
Although there is evidence for metabolic dysfunction and chronic inflammation in Alzheimer's disease (AD), circulating levels of soluble receptor for advanced glycation end products (sRAGE) and the receptor for advanced glycation end products (RAGE) ligand S100B have not been characterized. sRAGE is an important mediator in disease as it can act as a ligand decoy for RAGE and attenuate downstream inflammatory signaling. Cognitively healthy elderly and AD participants with and without type 2 diabetes (n = 135) were stratified according to the clinical dementia rating (CDR; 0 = normal cognition (NC); ≥0.5 = AD). Total serum sRAGE, endogenous secretory RAGE (esRAGE), and S100B were assayed via ELISAs, and cleaved RAGE (cRAGE) and the cRAGE : esRAGE ratio were calculated. cRAGE : esRAGE was lower in AD compared to NC (p < 0.05). Metabolic substratifications were used to investigate the factors that influence sRAGE pathology in AD. Stratification by BMI classification, median fat mass, median HOMA-IR, median insulin, and median amylin were all metabolic or anthropometric factors which significantly interacted with sRAGE profiles within AD subjects. There were no significant differences in serum S100B between groups. These characterizations of sRAGE contribute evidence to the link between impaired metabolism and cognitive decline due to AD.
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Doença de Alzheimer/metabolismo , Isoformas de Proteínas/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Idoso , Feminino , Produtos Finais de Glicação Avançada/metabolismo , Humanos , Insulina/metabolismo , Masculino , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismoRESUMO
The soluble receptor for advanced glycation end products (sRAGE) may be protective against inflammation associated with obesity and type 2 diabetes (T2DM). The aim of this study was to determine the distribution of sRAGE isoforms and whether sRAGE isoforms are associated with risk of T2DM development in subjects spanning the glucose tolerance continuum. In this retrospective analysis, circulating total sRAGE and endogenous secretory RAGE (esRAGE) were quantified via ELISA, and cleaved RAGE (cRAGE) was calculated in 274 individuals stratified by glucose tolerance status (GTS) and obesity. Group differences were probed by ANOVA, and multivariate ordinal logistic regression was used to test the association between sRAGE isoform concentrations and the proportional odds of developing diabetes, vs. normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). When stratified by GTS, total sRAGE, cRAGE, and esRAGE were all lower with IGT and T2DM, while the ratio of cRAGE to esRAGE (cRAGE:esRAGE) was only lower (P < 0.01) with T2DM compared with NGT. When stratified by GTS and obesity, cRAGE:esRAGE was higher with obesity and lower with IGT (P < 0.0001) compared with lean, NGT. In ordinal logistic regression models, greater total sRAGE (odds ratio, 0.91; P < 0.01) and cRAGE (odds ratio, 0.84; P < 0.01) were associated with lower proportional odds of developing T2DM. Reduced values of sRAGE isoforms observed with both obesity and IGT are independently associated with greater proportional odds of developing T2DM. The mechanisms by which each respective isoform contributes to obesity and insulin resistance may reveal novel treatment strategies for diabetes.
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Diabetes Mellitus Tipo 2/sangue , Intolerância à Glucose/sangue , Obesidade/sangue , Receptor para Produtos Finais de Glicação Avançada/sangue , Adolescente , Adulto , Idoso , Envelhecimento/metabolismo , Glicemia/análise , Índice de Massa Corporal , Diabetes Mellitus Tipo 2/complicações , Progressão da Doença , Feminino , Intolerância à Glucose/complicações , Teste de Tolerância a Glucose , Hemoglobinas Glicadas/análise , Humanos , Isomerismo , Masculino , Pessoa de Meia-Idade , Obesidade/complicações , Sobrepeso/sangue , Sobrepeso/complicações , Receptor para Produtos Finais de Glicação Avançada/química , Estudos Retrospectivos , Adulto JovemRESUMO
BACKGROUND: Increased dietary whole-grain intake may protect against cardiovascular disease (CVD). OBJECTIVE: The objective was to evaluate the efficacy of whole grains compared with refined grains on body composition, hypertension, and related mediators of CVD in overweight and obese adults. METHODS: We conducted a double-blind, randomized, controlled crossover trial in 40 overweight or obese men and women aged <50 y with no known history of CVD. Complete whole-grain and refined-grain diets were provided for two 8-wk periods, with a 10-wk washout between diets. Macronutrient composition was matched, except for the inclusion of either whole grains or refined grains (50 g/1000 kcal in each diet). Measurements included blood pressure, body composition, blood lipids and adiponectin, and markers of inflammation and glycemia. RESULTS: Thirty-three participants (6 men and 27 women) completed the trial [mean ± SD age: 39 ± 7 y; mean ± SD body mass index (in kg/m2): 33.1 ± 4.3]. Decreases in diastolic blood pressure were -5.8 mm Hg (95% CI: -7.7, -4.0 mm Hg) after the whole-grain diet and -1.6 mm Hg (95% CI: -4.4, 1.3 mm Hg) after the control diet (between effect, P = 0.01). Decreases in plasma adiponectin were -0.1 (95% CI: -0.9, 0.7) after the whole-grain diet and -1.4 (95% CI: -2.6, -0.3) after the control diet (between effect, P = 0.05). Decreases in diastolic blood pressure correlated with the circulating adiponectin concentration (r = 0.35, P = 0.04). Substantial reductions in body weight, fat loss, systolic blood pressure, total cholesterol, and LDL cholesterol were observed during both diet periods, with no relevant difference between them. CONCLUSIONS: The improvement in diastolic blood pressure was >3-fold greater in overweight and obese adults when they consumed a whole-grain compared with a refined-grain diet. Because diastolic blood pressure predicts mortality in adults aged <50 y, increased whole-grain intake may provide a functional approach to control hypertension. This may benefit patients at risk of vascular-related morbidity and mortality. This trial was registered at clinicaltrials.gov as NCT01411540.
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Doenças Cardiovasculares/prevenção & controle , Dieta , Sobrepeso , Grãos Integrais , Adulto , Glicemia , Pressão Sanguínea , Composição Corporal , Método Duplo-Cego , Feminino , Humanos , Resistência à Insulina , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
Insulin is a vasoactive hormone that regulates vascular homeostasis by maintaining balance of endothelial-derived NO and ET-1. Although there is general agreement that insulin resistance and the associated hyperinsulinemia disturb this balance, the vascular consequences for hyperinsulinemia in isolation from insulin resistance are still unclear. Presently, there is no simple answer for this question, especially in a background of mixed reports examining the effects of experimental hyperinsulinemia on endothelial-mediated vasodilation. Understanding the mechanisms by which hyperinsulinemia induces vascular dysfunction is essential in advancing treatment and prevention of insulin resistance-related vascular complications. Thus, we review literature addressing the effects of hyperinsulinemia on vascular function. Furthermore, we give special attention to the vasoregulatory effects of hyperinsulinemia on skeletal muscle, the largest insulin-dependent organ in the body. This review also characterizes the differential vascular effects of hyperinsulinemia on large conduit vessels versus small resistance microvessels and the effects of metabolic variables in an effort to unravel potential sources of discrepancies in the literature. At the cellular level, we provide an overview of insulin signaling events governing vascular tone. Finally, we hypothesize a role for hyperinsulinemia and insulin resistance in the development of CVD.
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Hiperinsulinismo , Resistência à Insulina , Insulina/metabolismo , Músculo Esquelético , Doenças Vasculares , Animais , Humanos , Hiperinsulinismo/metabolismo , Hiperinsulinismo/fisiopatologia , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Óxido Nítrico/metabolismo , Doenças Vasculares/metabolismo , Doenças Vasculares/fisiopatologiaRESUMO
The objective of this study was to establish whether alterations in the REDD1-mTOR axis underlie skeletal muscle insensitivity to insulin in Type 2 diabetic (T2D), obese individuals. Vastus lateralis muscle biopsies were obtained from lean, control and obese, T2D subjects under basal and after a 2-h hyperinsulinemic (40 mU·m(-2)·min(-1))-euglycemic (5 mM) clamp. Muscle lysates were examined for total REDD1, and phosphorylated Akt, S6 kinase 1 (S6K1), 4E-BP1, ERK1/2, and MEK1/2 via Western blot analysis. Under basal conditions [(-) insulin], T2D muscle exhibited higher S6K1 and ERK1/2 and lower 4E-BP1 phosphorylation (P < 0.05), as well as elevations in blood cortisol, glucose, insulin, glycosylated hemoglobin (P < 0.05) vs. lean controls. Following insulin infusion, whole body glucose disposal rates (GDR; mg/kg/min) were lower (P < 0.05) in the T2D vs. the control group. The basal-to-insulin percent change in REDD1 expression was higher (P < 0.05) in muscle from the T2D vs. the control group. Whereas, the basal-to-insulin percent change in muscle Akt, S6K1, ERK1/2, and MEK1/2 phosphorylation was significantly lower (P < 0.05) in the T2D vs. the control group. Findings from this study propose a REDD1-regulated mechanism in T2D skeletal muscle that may contribute to whole body insulin resistance and may be a target to improve insulin action in insulin-resistant individuals.
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Diabetes Mellitus Tipo 2/metabolismo , Insulina/farmacologia , Complexos Multiproteicos/metabolismo , Músculo Esquelético/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Fatores de Transcrição/metabolismo , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina , Pessoa de Meia-Idade , Complexos Multiproteicos/genética , Músculo Esquelético/efeitos dos fármacos , Serina-Treonina Quinases TOR/genética , Fatores de Transcrição/genéticaRESUMO
Plasma glucose, insulin, and C-peptide responses during an OGTT are informative for both research and clinical practice in type 2 diabetes. The aim of this study was to use such information to determine insulin sensitivity and insulin secretion so as to calculate an oral glucose disposition index (DI(OGTT)) that is a measure of pancreatic ß-cell insulin secretory compensation for changing insulin sensitivity. We conducted an observational study of n = 187 subjects, representing the entire glucose tolerance continuum from normal glucose tolerance to type 2 diabetes. OGTT-derived insulin sensitivity (S(I OGTT)) was calculated using a novel multiple-regression model derived from insulin sensitivity measured by hyperinsulinemic euglycemic clamp as the independent variable. We also validated the novel S(I OGTT) in n = 40 subjects from an independent data set. Plasma C-peptide responses during OGTT were used to determine oral glucose-stimulated insulin secretion (GSIS(OGTT)), and DI(OGTT) was calculated as the product of S(I OGTT) and GSIS(OGTT). Our novel S(I OGTT) showed high agreement with clamp-derived insulin sensitivity (typical error = +3.6%; r = 0.69, P < 0.0001) and that insulin sensitivity was lowest in subjects with impaired glucose tolerance and type 2 diabetes. GSIS(OGTT) demonstrated a significant inverse relationship with S(I OGTT). GSIS(OGTT) was lowest in normal glucose-tolerant subjects and greatest in those with impaired glucose tolerance. DI(OGTT) was sequentially lower with advancing glucose intolerance. We hereby derive and validate a novel OGTT-derived measurement of insulin sensitivity across the entire glucose tolerance continuum and demonstrate that ß-cell compensation for changing insulin sensitivity can be readily calculated from clinical variables collected during OGTT.
Assuntos
Alostase , Diabetes Mellitus Tipo 2/diagnóstico , Intolerância à Glucose/diagnóstico , Resistência à Insulina , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Estado Pré-Diabético/diagnóstico , Glicemia/análise , Estudos de Coortes , Dinamarca , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Diagnóstico Diferencial , Progressão da Doença , Feminino , Técnica Clamp de Glucose , Intolerância à Glucose/sangue , Intolerância à Glucose/metabolismo , Intolerância à Glucose/fisiopatologia , Teste de Tolerância a Glucose , Hemoglobinas Glicadas/análise , Humanos , Insulina/sangue , Secreção de Insulina , Masculino , Pessoa de Meia-Idade , Ohio , Estado Pré-Diabético/sangue , Estado Pré-Diabético/metabolismo , Estado Pré-Diabético/fisiopatologiaRESUMO
Glyoxalase I (GLO1) is the primary enzyme for detoxification of the reactive dicarbonyl methylglyoxal (MG). Loss of GLO1 promotes accumulation of MG resulting in a recapitulation of diabetic phenotypes. We previously demonstrated attenuated GLO1 protein in skeletal muscle from individuals with type 2 diabetes (T2D). However, whether GLO1 attenuation occurs prior to T2D and the mechanisms regulating GLO1 abundance in skeletal muscle are unknown. GLO1 expression and activity were determined in skeletal muscle tissue biopsies from 15 lean healthy individuals (LH, BMI: 22.4 ± 0.7) and 5 individuals with obesity (OB, BMI: 32.4 ± 1.3). GLO1 protein was attenuated by 26 ± 0.3 % in OB compared to LH skeletal muscle (p = 0.019). Similar reductions for GLO1 activity were observed (p = 0.102). NRF2 and Keap1 expression were equivocal between groups despite a 2-fold elevation in GLO1 transcripts in OB skeletal muscle (p = 0.008). GLO1 knock-down (KD) in human immortalized myotubes promoted downregulation of muscle contraction and organization proteins indicating the importance of GLO1 expression for skeletal muscle function. SIRT1 KD had no effect on GLO1 protein or activity whereas, SIRT2 KD attenuated GLO1 protein by 28 ± 0.29 % (p < 0.0001) and GLO1 activity by 42 ± 0.12 % (p = 0.0150). KD of NAMPT also resulted in attenuation of GLO1 protein (28 ± 0.069 %, p = 0.003), activity (67 ± 0.09 %, p = 0.011) and transcripts (50 ± 0.13 %, p = 0.049). Neither the provision of the NAD+ precursors NR nor NMN were able to prevent this attenuation in GLO1 protein. However, NR did augment GLO1 specific activity (p = 0.022 vs NAMPT KD). These perturbations did not alter GLO1 acetylation status. SIRT1, SIRT2 and NAMPT protein levels were all equivocal in skeletal muscle tissue biopsies from individuals with obesity and lean individuals. These data implicate NAD+-dependent regulation of GLO1 in skeletal muscle independent of altered GLO1 acetylation and provide rationale for exploring NR supplementation to rescue attenuated GLO1 abundance and activity in conditions such as obesity.
Assuntos
Citocinas , Lactoilglutationa Liase , Músculo Esquelético , Nicotinamida Fosforribosiltransferase , Obesidade , Sirtuína 2 , Humanos , Músculo Esquelético/metabolismo , Lactoilglutationa Liase/metabolismo , Lactoilglutationa Liase/genética , Nicotinamida Fosforribosiltransferase/metabolismo , Nicotinamida Fosforribosiltransferase/genética , Sirtuína 2/metabolismo , Sirtuína 2/genética , Citocinas/metabolismo , Masculino , Obesidade/metabolismo , Obesidade/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Fator 2 Relacionado a NF-E2/genética , Feminino , Adulto , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Regulação da Expressão Gênica , Pessoa de Meia-Idade , Sirtuína 1/metabolismo , Sirtuína 1/genéticaRESUMO
Background: Postural instability and gait difficulties (PIGD) are a significant cause of falls, mobility loss, and lower quality of life in Parkinson's disease (PD). The connection between PD progression and diminished strength in the lower limbs has been acknowledged. However, the identification of specific muscle groups linked to PIGD and non-PIGD motor features is still unknown. Objective: To explore the relationship between the strength of specific lower limb muscle groups, along with muscle mass, and their associations with PIGD, PIGD subtypes, and non-PIGD motor features in PD. Methods: 95 PD participants underwent detailed motor and non-motor test batteries, including lower limb isometric strength testing and whole-body lean mass assessments. Correlation analysis and univariate and multivariate linear/logistic forward stepwise regression were performed to test associations between PIGD and non-PIGD motor features with normalized value (z-score) of lower limb muscle strength and measures of lean mass. Results: Multivariate regression analysis, adjusted for age, gender, and levodopa equivalent dose, revealed that hip abductor strength was significantly associated with overall PIGD motor severity ratings (p < 0.001), impaired balance (p < 0.001), and non-PIGD Parkinsonian motor features (p < 0.001). Conversely, hip extensor strength was significantly associated with falls, slow walking, and FoG motor features (p=0.016; p=0.003; p=0.020, respectively). Conclusion: We found that lower hip abductor strength was associated with PIGD and non-PIGD motor features. The association between non-PIGD motor features may suggest specific vulnerability of the hip abductors as part of a proposed brain-muscle loop hypothesis in PD. Moreover, lower hip extensor strength correlated with falls, slow walking, and FoG.
RESUMO
Tendon biomechanical properties and fibril organization are altered in patients with diabetes compared to healthy individuals, yet few biomarkers have been associated with in vivo tendon properties. We investigated the relationships between in vivo imaging-based tendon properties, serum variables, and patient characteristics across healthy controls (n = 14, age: 45 ± 5 years, body mass index [BMI]: 24 ± 1, hemoglobin A1c [HbA1c]: 5.3 ± 0.1%), prediabetes (n = 14, age: 54 ± 5 years, BMI: 29 ± 2; HbA1c: 5.7 ± 0.1), and type 2 diabetes (n = 13, age: 55 ± 3 years, BMI: 33 ± 2, HbA1c: 6.7 ± 0.3). We used ultrasound speckle-tracking and measurements from magnetic resonance imaging (MRI) to estimate the patellar tendon in vivo tangent modulus. Analysis of plasma c-peptide, interleukin-1ß (IL-1ß), IL-6, IL-8, tumor necrosis factor-α (TNF-α), adiponectin, leptin, insulin-like growth factor 1 (IGF-1), and C-reactive protein (CRP) was completed. We built regression models incorporating statistically significant covariates and indicators for the clinically defined groups. We found that tendon cross-sectional area normalized to body weight (BWN CSA) and modulus were lower in patients with type 2 diabetes than in healthy controls (p < 0.05). Our regression analysis revealed that a model that included BMI, leptin, high-density lipoprotein (HDL), low-density lipoprotein (LDL), age, and group explained ~70% of the variability in BWN CSA (R2 = 0.70, p < 0.001). For modulus, including the main effects LDL, groups, HbA1c, age, BMI, cholesterol, IGF-1, c-peptide, leptin, and IL-6, accounted for ~54% of the variability in modulus (R2 = 0.54, p < 0.05). While BWN CSA and modulus were lower in those with diabetes, group was a poor predicter of tendon properties when considering the selected covariates. These data highlight the multifactorial nature of tendon changes with diabetes and suggest that blood variables could be reliable predictors of tendon properties.
Assuntos
Diabetes Mellitus Tipo 2 , Ligamento Patelar , Estado Pré-Diabético , Humanos , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/fisiopatologia , Pessoa de Meia-Idade , Masculino , Feminino , Estado Pré-Diabético/sangue , Estado Pré-Diabético/fisiopatologia , Ligamento Patelar/diagnóstico por imagem , Adulto , Fenômenos Biomecânicos , Estudos de Casos e Controles , Imageamento por Ressonância Magnética , UltrassonografiaRESUMO
BACKGROUND: Exercise intolerance is common among adults with heart failure (HF) and is a strong prognostic indicator. We examined maximal inspiratory pressure (MIP) as an indicator of maximal and submaximal exercise capacity in older HF patients. METHODS: Fifty-one patients age ≥ 50 years with HF underwent MIP testing via the PrO2 device. Peak oxygen uptake (VO2), 6 min walk distance (6MWD), 30 s sit-to-stand test (STS), gait speed (GS), grip strength and lower extremity muscle strength [one-repetition maximum (1RM)] were measured. Correlation and exploratory multiple regression analyses investigated relationships between MIP, left ventricular ejection fraction (LVEF), age, body mass index (BMI) and physical function. MIP was then stratified by median (64 cm H2O), and endpoints were compared between median groups. RESULTS: The median age was 69 years [interquartile range (IQR): 66-73], and the median LVEF was 36.5% (IQR: 30%-45%). Regression identified MIP as an independent predictor for grip strength, 6MWD, 1RM weight and 30 s STS after adjustment for age, BMI and LVEF. MIP greater than the median (n = 25) independently predicted and reflected greater peak VO2 [14.2 (12.8-18.1) vs. 11.5 (9.7-13.0) mL/kg/min; P = 0.0007] as well as 6MWD, 1RM, 30 s STS and GS (all P < 0.05). CONCLUSION: The analysis demonstrates that MIP is a novel biometric for exercise tolerance in adults with HF. Assessments of MIP are safe and convenient, with the potential to enhance routine HF surveillance and provide novel biometrics to guide HF therapeutics.
RESUMO
Impaired fasting glucose (IFG) blunts the reversal of impaired glucose tolerance (IGT) after exercise training. Metabolic inflexibility has been implicated in the etiology of insulin resistance; however, the efficacy of exercise on peripheral and hepatic insulin sensitivity or substrate utilization in adults with IFG, IGT, or IFG + IGT is unknown. Twenty-four older (66.7 ± 0.8 yr) obese (34.2 ± 0.9 kg/m(2)) adults were categorized as IFG (n = 8), IGT (n = 8), or IFG + IGT (n = 8) according to a 75-g oral glucose tolerance test (OGTT). Subjects underwent 12-wk of exercise (60 min/day for 5 days/wk at â¼85% HRmax) and were instructed to maintain a eucaloric diet. A euglycemic hyperinsulinemic clamp (40 mU·m(2)·min(-1)) with [6,6-(2)H]glucose was used to determine peripheral and hepatic insulin sensitivity. Nonoxidative glucose disposal and metabolic flexibility [insulin-stimulated respiratory quotient (RQ) minus fasting RQ] were also assessed. Glucose incremental area under the curve (iAUCOGTT) was calculated from the OGTT. Exercise increased clamp-derived peripheral and hepatic insulin sensitivity more in adults with IFG or IGT alone than with IFG + IGT (P < 0.05). Exercise reduced glucose iAUCOGTT in IGT only (P < 0.05), and the decrease in glucose iAUCOGTT was inversely correlated with the increase in peripheral but not hepatic insulin sensitivity (P < 0.01). Increased clamp-derived peripheral insulin sensitivity was also correlated with enhanced metabolic flexibility, reduced fasting RQ, and higher nonoxidative glucose disposal (P < 0.05). Adults with IFG + IGT had smaller gains in clamp-derived peripheral insulin sensitivity and metabolic flexibility, which was related to blunted improvements in postprandial glucose. Additional work is required to assess the molecular mechanism(s) by which chronic hyperglycemia modifies insulin sensitivity following exercise training.
Assuntos
Exercício Físico/fisiologia , Intolerância à Glucose/metabolismo , Resistência à Insulina , Obesidade/metabolismo , Estado Pré-Diabético/metabolismo , Idoso , Glicemia/metabolismo , Jejum/sangue , Jejum/metabolismo , Feminino , Intolerância à Glucose/sangue , Teste de Tolerância a Glucose , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/sangue , Obesidade/complicações , Fenótipo , Educação Física e Treinamento , Estado Pré-Diabético/sangueRESUMO
BACKGROUND: Alternate day fasting (ADF; ad libitum "feed day", alternated with 25% energy intake "fast day"), is effective for weight loss and cardio-protection in obese individuals. Whether these effects occur in normal weight and overweight individuals remains unknown. This study examined the effect of ADF on body weight and coronary heart disease risk in non-obese subjects. METHODS: Thirty-two subjects (BMI 20-29.9 kg/m2) were randomized to either an ADF group or a control group for 12 weeks. RESULTS: Body weight decreased (P < 0.001) by 5.2 ± 0.9 kg (6.5 ± 1.0%) in the ADF group, relative to the control group, by week 12. Fat mass was reduced (P < 0.001) by 3.6 ± 0.7 kg, and fat free mass did not change, versus controls. Triacylglycerol concentrations decreased (20 ± 8%, P < 0.05) and LDL particle size increased (4 ± 1 Å, P < 0.01) in the ADF group relative to controls. CRP decreased (13 ± 17%, P < 0.05) in the ADF group relative to controls at week 12. Plasma adiponectin increased (6 ± 10%, P < 0.01) while leptin decreased (40 ± 7%, P < 0.05) in the ADF group versus controls by the end of the study. LDL cholesterol, HDL cholesterol, homocysteine and resistin concentrations remained unchanged after 12 weeks of treatment. CONCLUSION: These findings suggest that ADF is effective for weight loss and cardio-protection in normal weight and overweight adults, though further research implementing larger sample sizes is required before solid conclusion can be reached.