Genetically defined favourable adiposity is not associated with a clinically meaningful difference in clinical course in people with type 2 diabetes but does associate with a favourable metabolic profile.

AIMS: Change in weight, HbA1c , lipids, blood pressure and cardiometabolic events over time is variable in individuals with type 2 diabetes. We hypothesised that people with a genetic predisposition to a more favourable adiposity distribution could have a less severe clinical course/progression. METHODS: We involved people with type 2 diabetes from two UK-based cohorts: 11,914 individuals with GP follow-up data from the UK Biobank and 723 from Salford. We generated a 'favourable adiposity' genetic score and conducted cross-sectional and longitudinal studies to test its association with weight, BMI, lipids, blood pressure, medication use and risk of myocardial infarction and stroke using 15 follow-up time points with 1-year intervals. RESULTS: The 'favourable adiposity' genetic score was cross-sectionally associated with higher weight (effect size per 1 standard deviation higher genetic score: 0.91 kg [0.59,1.23]) and BMI (0.30 kg/m2 [0.19,0.40]), but higher high-density lipoprotein (0.02 mmol/L [0.01,0.02]) and lower triglycerides (-0.04 mmol/L [-0.07, -0.02]) in the UK Biobank at baseline, and this pattern of association was consistent across follow-up. There was a trend for participants with higher 'favourable adiposity' genetic score to have lower risk of myocardial infarction and/or stroke (odds ratio 0.79 [0.62, 1.00]) compared to those with lower score. A one standard deviation higher score was associated with lower odds of using lipid-lowering (0.91 [0.86, 0.97]) and anti-hypertensive medication (0.95 [0.91, 0.99]). CONCLUSIONS: In individuals with type 2 diabetes, having more 'favourable adiposity' alleles is associated with a marginally better lipid profile long-term and having lower odds of requiring lipid-lowering or anti-hypertensive medication in spite of relatively higher adiposity.

Assessment of global long interspersed nucleotide element-1 (LINE-1) DNA methylation in a longitudinal cohort of type 2 diabetes mellitus (T2DM) individuals.

INTRODUCTION: Recent studies have indicated that methylation of the LINE-1 elements is associated with an increased risk of worsening carbohydrate metabolism. It has been shown that overall DNA methylation of LINE-1 elements could be considered as a risk factor for T2DM and its complications, independent of other established risk factors. METHODS: A total of 794 T2DM individuals from Salford, UK were included in this study (60% men n = 470). All patients had clinical and metabolic variables measured in 2002 (baseline outcomes) and annually through to 2016. Global LINE-1 DNA methylation was measured at four CpG sites. The QIAGEN PyroMark Q96 MD pyrosequencer was used to quantify methylation. RESULTS: The overall mean ± SD global LINE-1 methylation was 75.81 ± 3.25%. Cross-sectional linear regression analysis at baseline year 2002 showed that LINE-1 methylation was a significant predictor of diastolic BP (adjusted beta coefficient ß = -0.25), estimated glomerular filtration rate (eGFR) (ß = -0.48) and cholesterol HDL ratio (ß = -0.04). A 10% increase in LINE-1 methylation was associated with a lower diastolic BP by 2.5 mm Hg, a lower eGFR by 4.8 ml/min/1.73 m2 and decreased cholesterol/HDL ratio by 0.4 mmol/L. Longitudinal analysis over the 14-year-follow-up periods showed that global LINE-1 methylation at baseline was associated with lower BMI in women [ß = -0.25] and lower cholesterol: HDL ratio [ß = -0.07]. A 10% increase in LINE-1 methylation was associated with reduction in BMI by 2.5 kg/m2 in women and reduction in cholesterol:HDL ratio by 0.7 mmol/L. CONCLUSION: In a 14-year longitudinal cohort of T2DM individuals, relations between global LINE-1 DNA methylation status and specific metabolic markers were seen. Also, a higher degree of DNA methylation was predictive of less weight gain over time in women.

Statins inhibit insulin-like growth factor action in first trimester placenta by altering insulin-like growth factor 1 receptor glycosylation.

The rapid rise in obesity, metabolic syndrome and type 2 diabetes is one of the major healthcare problems of the Western world. Affected individuals are often treated with statins (3-hydroxy-3-methylglutaryl co-enzyme A [HMG CoA] reductase inhibitors) to reduce circulating cholesterol levels and the risk of developing cardiovascular disease; given the evolving demographic profile of these conditions, such drugs are increasingly prescribed to women of reproductive age. We have previously shown that exposure of placental tissue to statins inhibits the action of insulin-like growth factors (IGF)-I and -II which are key regulators of trophoblast proliferation and placental development. N-linked glycans in the IGF receptor, IGF1R, influence its presentation at the cell surface. This study aimed to determine whether statins, which are known to affect N-glycosylation, modulate IGF1R function in placenta. Treatment of first trimester villous tissue explants with statins (pravastatin or cerivastatin) or inhibitors of N-glycosylation (tunicamycin, deoxymannojirimycin or castanospermine) altered receptor distribution in trophoblast and attenuated proliferation induced by IGF-I or IGF-II (Ki67; P < 0.05, n = 5). Decreased binding of Phaseolus vulgaris lectin and phytohaemagglutinin to IGF1R immunoprecipitated from treated explants demonstrated reduced levels of complex N-linked glycans. Co-incubation of tissue explants with statins and farnesyl pyrophosphate (which increases the supply of dolichol intermediates), prevented statin-mediated disruption of IGF1R localization and reversed the negative effect on IGF-mediated trophoblast proliferation. These data suggest that statins attenuate IGF actions in the placenta by inhibiting N-linked glycosylation and subsequent expression of mature IGF1R at the placental cell surface.

Reverse cardiac remodelling and renal functional improvement following bilateral renal artery stenting for flash pulmonary oedema.

Acute flash pulmonary oedema (AFPO) is a life-threatening syndrome almost unique to patients with atheromatous renovascular disease (ARVD). Although recurrent AFPO is a widely accepted indication to consider renal revascularization, this is based on a number of case reports/series describing a successful outcome post-procedure. There is limited literature on the pathophysiological mechanisms and treatment effects of revascularization to support this clinical decision making. We report the case of a 65-year-old lady who presented with three episodes of AFPO. Investigations revealed severe bilateral renal artery stenosis. Post-revascularization, she experienced substantial improvement in energy levels and New York Heart Association class, with improvement in her blood pressure and renal function. Post-procedure, there were dramatic improvements in her cardiac morphology and function that were sustained at 1 year (ejection fraction improved from 39 to 65%, left ventricular mass decreased from 161 to 116 g) as well as renal function (isotopic glomerular filtration rate increased from 22.4 to 34.2 mL/min). This report provides new insights into the pathophysiological relationships between renal and cardiac changes in AFPO; the extent of the cardiac morphological changes was striking and unexpected.

Apposite insulin-like growth factor (IGF) receptor glycosylation is critical to the maintenance of vascular smooth muscle phenotype in the presence of factors promoting osteogenic differentiation and mineralization.

Vascular calcification is strongly linked with increased morbidity and mortality from cardiovascular disease. Vascular calcification is an active cell-mediated process that involves the differentiation of vascular smooth muscle cells (VSMCs) to an osteoblast-like phenotype. Several inhibitors of this process have been identified, including insulin-like growth factor-I (IGF-I). In this study, we examined the role of the IGF receptor (IGFR) and the importance of IGFR glycosylation in the maintenance of the VSMC phenotype in the face of factors known to promote osteogenic conversion. IGF-I (25 ng/ml) significantly protected VSMCs from ß-glycerophosphate-induced osteogenic differentiation (p < 0.005) and mineral deposition (p < 0.01). Mevalonic acid depletion (induced by 100 nm cerivastatin) significantly inhibited these IGF protective effects (p < 0.01). Mevalonic acid depletion impaired IGFR processing, decreased the expression of mature IGFRs at the cell surface, and inhibited the downstream activation of Akt and MAPK. Inhibitors of N-linked glycosylation (tunicamycin, deoxymannojirimycin, and deoxynojirimycin) also markedly attenuated the inhibitory effect of IGF-I on ß-glycerophosphate-induced mineralization (p < 0.05) and activation of Akt and MAPK. These results demonstrate that alterations in the glycosylation of the IGFR disrupt the ability of IGF-I to protect against the osteogenic differentiation and mineralization of VSMCs by several interrelated mechanisms: decreased IGFR processing, reduced IGFR cell-surface expression, and reduced downstream signaling via the Akt and MAPK pathways. IGF-I thus occupies a critical position in the maintenance of normal VSMC phenotype and protection from factors known to stimulate vascular calcification.

Methylation Status of Exon IV of the Brain-Derived Neurotrophic Factor (BDNF)-Encoding Gene in Patients with Non-Diabetic Hyperglycaemia (NDH) before and after a Lifestyle Intervention.

BDNF signalling in hypothalamic neuronal circuits is thought to regulate mammalian food intake. In light of this, we investigated how a lifestyle intervention influenced serum levels and DNA methylation of BDNF gene in fat tissue and buffy coat of NDH individuals. In total, 20 participants underwent anthropometric measurements/fasting blood tests and adipose tissue biopsy pre-/post-lifestyle (6 months) intervention. DNA was extracted from adipose tissue and buffy coat, bisulphite converted, and pyrosequencing was used to determine methylation levels in exon IV of the BDNF gene. RNA was extracted from buffy coat for gene expression analysis and serum BDNF levels were measured by ELISA. No differences were found in BDNF serum levels, but buffy coat mean BDNF gene methylation decreased post-intervention. There were correlations between BDNF serum levels and/or methylation and cardiometabolic markers. (i) Pre-intervention: for BDNF methylation, we found positive correlations between mean methylation in fat tissue and waist-hip ratio, and negative correlations between mean methylation in buffy coat and weight. (ii) Post-intervention: we found correlations between BDNF mean methylation in buffy coat and HbA1c, BDNF methylation in buffy coat and circulating IGFBP-2, and BDNF serum and insulin. Higher BDNF % methylation levels are known to reduce BNDF expression. The fall in buffy coat mean BDNF methylation plus the association between lower BDNF methylation (so potentially higher BDNF) and higher HbA1c and serum IGFBP-2 (as a marker of insulin sensitivity) and between lower serum BDNF and higher circulating insulin are evidence for the degree of BDNF gene methylation being implicated in insulinisation and glucose homeostasis, particularly after lifestyle change in NDH individuals.

Bariatric Surgery-induced High-density Lipoprotein Functionality Enhancement Is Associated With Reduced Inflammation.

BACKGROUND: Emerging evidence suggests an association between impaired high-density lipoprotein (HDL) functionality and cardiovascular disease (CVD). HDL is essential for reverse cholesterol transport (RCT) and reduces inflammation and oxidative stress principally via paraoxonase-1 (PON1). RCT depends on HDL's capacity to accept cholesterol (cholesterol efflux capacity [CEC]) and active transport through ATP-binding cassette (ABC) A1, G1, and scavenger receptor-B1 (SR-B1). We have studied the impact of Roux-en-Y gastric bypass (RYGB) in morbidly obese subjects on RCT and HDL functionality. METHODS: Biomarkers associated with increased CVD risk including tumour necrosis factor-α (TNF-α), high-sensitivity C-reactive protein (hsCRP), myeloperoxidase mass (MPO), PON1 activity, and CEC in vitro were measured in 44 patients before and 6 and 12 months after RYGB. Overweight but otherwise healthy (mean body mass index [BMI] 28 kg/m2) subjects acted as controls. Twelve participants also underwent gluteal subcutaneous adipose tissue biopsies before and 6 months after RYGB for targeted gene expression (ABCA1, ABCG1, SR-B1, TNF-α) and histological analysis (adipocyte size, macrophage density, TNF-α immunostaining). RESULTS: Significant (P < 0.05) improvements in BMI, HDL-cholesterol, hsCRP, TNF-α, MPO mass, PON1 activity, and CEC in vitro were observed after RYGB. ABCG1 (fold-change, 2.24; P = 0.005) and ABCA1 gene expression increased significantly (fold-change, 1.34; P = 0.05). Gluteal fat adipocyte size (P < 0.0001), macrophage density (P = 0.0067), and TNF-α immunostaining (P = 0.0425) were reduced after RYBG and ABCG1 expression correlated inversely with TNF-α immunostaining (r = -0.71; P = 0.03). CONCLUSION: RYGB enhances HDL functionality in association with a reduction in adipose tissue and systemic inflammation.

Reduced pericellular sensitivity to IGF-I in fibroblasts from girls with Turner syndrome: a mechanism to impair clinical responses to GH.

Girls with Turner syndrome (TS) are treated with supraphysiological doses of growth hormone (GH) to improve final height; however in some girls, the growth response can be poor. This may reflect aberrations in GH and/or IGF-I actions at the cellular level, and thus this study compared the response of skin fibroblasts from normal children (n = 5) and girls with TS (n = 8) to GH, IGF-I, or a combination, by assessing the IGF binding protein (IGFBP) profile of conditioned medium harvested over 7 d. The two cell types had a comparable IGFBP profile; IGFBP-3 and IGFBP-4 were the most abundant species. TS fibroblasts produced more IGFBP-3 (d 7, 51.4 ± 45 ng/mL versus 20 ± 22 ng/mL; p < 0.05) than control cells; levels of IGFBP-4 were similar (21 ± 12 ng/mL versus 30 ± 21 ng/mL). GH did not influence IGFBP production. IGF-I treatment did not affect IGFBP-4 levels but enhanced the production of IGFBP-3 by both cell types (p < 0.05). However, the response of TS fibroblasts to IGF-I was approximately half that observed in normal cells (p < 0.05). Altered IGF-I activity, because of reduced bioavailability and/or reduced sensitivity, could contribute to the need for high GH doses in TS and for the poor response to GH in some girls with TS.

Androgen receptor-reduced sensitivity is associated with increased mortality and poorer glycaemia in men with type 2 diabetes mellitus: a prospective cohort study.

INTRODUCTION: Hypogonadism is associated with poorer glycaemic outcomes/increased all-cause and cardiovascular morbidity/mortality in type 2 diabetes mellitus (T2DM). Increasing CAG repeat number within exon-1 of the androgen receptor (AR) gene is associated with increased AR resistance/insulin resistance. METHODS: We determined in a long-term 14-year follow-up cohort of 423 T2DM Caucasian men, the association between baseline androgen status/CAG repeat number (by PCR then Sequenom sequencing) and metabolic/cardiovascular outcomes. RESULTS: Metabolic outcomes: Lower total testosterone was associated with higher BMI (kg/m2) at 14-year-follow-up: regression coefficient -0.30 (95% confidence interval -0.445 to -0.157), P = 0.0001. The range of CAG repeat number was 9-29 repeats. Higher CAG repeat number in exon-1 of the AR gene was associated with higher follow-up HbA1c2016 - each unit increase in CAG repeat-associated with an increment of 0.1% in HbA1C2016 (P = 0.04), independent of baseline testosterone. Cardiovascular outcomes and mortality: At an average of 14-year-follow-up, 55.8% of hypogonadal men had died vs 36.1% of eugonadal men (P = 0.001). There was a 'u' shaped relation between number of CAG repeats and mortality. Twenty-one CAG repeats were associated with an up to nearly 50% lower mortality rate than <21 CAG repeats and >21 CAG repeats - independent of baseline testosterone level. CONCLUSION: A higher number of CAG repeats at the AR gene associates with higher future HbA1c. There was a 'u' shaped relation between CAG repeat number and mortality rate. Determination of CAG repeat number may become part of assessment of androgen status/its consequences for men with T2DM.

Circulating microRNA changes in patients with impaired glucose regulation.

We analysed if levels of four miRNAs would change after a lifestyle intervention involving dietary and exercises in prediabetes. MiRNAs previously shown to be associated with diabetes (Let-7a, Let-7e, miR-144 and miR-92a) were extracted from serum pre- and post-intervention. mRNA was extracted from fat-tissue for gene expression analyses. The intervention resulted in increased Let-7a and miR-92a. We found correlations between miRNAs and clinical variables (triglycerides, cholesterol, insulin, weight and BMI). We also found correlations between miRNAs and target genes, revealing a link between miR-92a and IGF system. A lifestyle intervention resulted in marked changes in miRNAs. The association of miRNAs with insulin and the IGF system (both receptors and binding proteins) may represent a mechanism of regulating IGFs metabolic actions.

Lifestyle intervention in individuals with impaired glucose regulation affects Caveolin-1 expression and DNA methylation.

AIMS: We investigated whether a lifestyle intervention could influence expression and DNA methylation of diabetes-related genes in patients with impaired glucose regulation (IGR), the results were compared to bariatric surgery, considering it an intensive change. METHODS: Twenty participants with IGR had adipose tissue biopsy and blood collected pre- and post-lifestyle (6 months) intervention; 12 obese patients had subcutaneous fat taken before and after bariatric surgery. RNA/DNA was extracted from all samples and underwent qPCR. DNA was bisulphite converted and 12 CpG sites of Caveolin-1 (CAV1) promoter were pyrosequenced. RESULTS: lifestyle intervention resulted in opposite direction changes in fat tissue and blood for CAV1 expression and DNA methylation and these changes were correlated between tissues, while no significative differences were found in CAV1 expression after bariatric surgery. CONCLUSIONS: Our findings suggest a role for CAV1 in modulating adipocyte function as a consequence of lifestyle changes, as exercises and diet. These results may provide insights into new therapeutic targets for diabetes prevention.

Data Independent Acquisition Mass Spectrometry Can Identify Circulating Proteins That Predict Future Weight Loss with a Diet and Exercise Programme.

We investigated biological determinants that would associate with the response to a diet and weight loss programme in impaired glucose regulation (IGR) people using sequential window acquisition of all theoretical fragment ion spectra (SWATH) mass spectrometry (MS), a data acquisition method which complement traditional mass spectrometry-based proteomics techniques. Ten women and 10 men with IGR underwent anthropometric measurements and fasting blood tests. SWATH MS was carried out with subsequent immunoassay of specific peptide levels. After a six-month intervention, 40% of participants lost 3% or more in weight, 45% of patients remained within 3% of their starting weight and 15% increased their weight by 3% or more. Hemoglobin A1c (HbA1C) level was reduced with weight loss with improvements in insulin sensitivity. SWATH MS on pre-intervention samples and subsequent principal component analysis identified a cluster of proteins associated with future weight loss, including insulin-like growth factor-II (IGF-II) and Vitamin D binding protein. Individuals who lost 3% in weight had significantly higher baseline IGF-II levels than those who did not lose weight. SWATH MS successfully discriminated between individuals who were more likely to lose weight and potentially improve their sensitivity to insulin. A higher IGF-II baseline was predictive of success with weight reduction, suggesting that biological determinants are important in response to weight loss and exercise regimes. This may permit better targeting of interventions to prevent diabetes in the future.

Male hypogonadism: 14-year prospective outcome in 550 men with type 2 diabetes.

INTRODUCTION: Hypogonadism is more prevalent in men with type 2 diabetes (T2DM) (25%-40%) than in men without T2DM. Hypogonadism has been associated with poorer glycaemic outcomes and increased cardiovascular morbidity/mortality. We report a 14-year follow-up study to evaluate the influence of baseline testosterone level on T2DM outcomes. RESEARCH DESIGN AND METHODS: A total of 550 men with T2DM underwent baseline total testosterone and dihydrotestosterone measurement by tandem mass spectrometry. Mean age of the men was 59.7 ± 12 (mean ± SD) years. Sex hormone-binding globulin (SHBG) was measured and free testosterone estimated. Patients were followed up between 2002 and 2016. Mean follow-up period was 12.2 ± 4 years using the Salford (UK) Integrated Health Records system. RESULTS: Mean baseline total testosterone was 13.7 ± 5.8 nmol/L, and mean free testosterone was 245.7 ± 88.0 pmol/L. Mean for low total testosterone (<10 nmol/L) was 7.6 ± 2.0 nmol/L (n = 154) and 142 men had a free testosterone <190 pmol/L. During the 14-year duration follow-up, 22% of men experienced a myocardial infarction, 18% experienced a stroke, 11% developed angina, 14% underwent coronary revascularization. About 38% of the men initially recruited died. A lower total testosterone was associated with a higher body mass index (kg/m2) at follow-up: regression coefficient -0.30 (95% CI -0.445 to -0.157), P = 0.0001. The mortality rate was higher in patients with lower total testosterone compared to normal baseline total testosterone (5.0% vs 2.8% per year, P < 0.0001). A similar phenomenon was seen for dihydrotestosterone (4.3% vs 2.9% per year, P = 0.002) for normal vs low dihydrotestosterone) and for lower SHBG. Over the whole follow-up period 36.1% (143/396), men with normal baseline testosterone died vs 55.8% (86/154) of hypogonadal men at baseline. In Cox regression, the age-adjusted hazard ratio (HR) for higher mortality associated with low total testosterone was 1.54 (95% CI: 1.2-2.0, P < 0.002), corresponding to a 3.2 year reduced life expectancy for hypogonadal T2DM men. CONCLUSION: Low testosterone and dihydrotestosterone levels are associated with higher all-cause mortality in T2DM men. Hypogonadal men with T2DM should be considered as very high risk for cardiovascular events/death.

The impact of abnormalities in IGF and inflammatory systems on the metabolic syndrome.

OBJECTIVE: Low plasma levels of IGF-I, particularly when coupled with low levels of the potentially inhibitory IGF binding protein (IGFBP)-1 and higher levels of C-reactive protein (CRP), have been implicated in the pathogenesis of metabolic syndrome X and cardiovascular disease. We report the relative contributions of IGFBP-1 and CRP to the occurrence of the metabolic syndrome in a healthy population cohort to establish the extent to which these factors may contribute to subsequent risk of cardiovascular disease. RESEARCH DESIGN AND METHODS: The volunteers in the study were all participants in the Ely study, a continuing population-based cohort in Ely, Cambridgeshire, U.K. Of 839 individuals studied, 154 (18.4%) fulfilled criteria for the metabolic syndrome. RESULTS: Subjects with the metabolic syndrome had lower IGFBP-1 (14.4 microg/l [95% CI 12.9-16.0] vs. 25.4 [24.1-26.7], P < 0.001) and higher CRP (1.9 mg/l [1.6-2.2] vs. 1.0 [0.9-1.1], P < 0.001). Logistic regression, adjusted for age, sex, fasting insulin, and IGF-I, demonstrated a striking 14-fold increased risk for the metabolic syndrome (odds ratio 14.1 [4.1-48.4], P < 0.001) in individuals with a CRP value in the highest tertile and IGFBP-1 levels below the median. CONCLUSIONS: The combination of a high CRP concentration coupled with a low IGFBP-1 results in a dramatic increase in an individual's risk of having the metabolic syndrome. Further elucidation of the biological processes linking the IGF and inflammatory systems may allow the identification of novel therapeutic targets for cardiovascular risk reduction.

Insulin-like growth factor-II and insulin-like growth factor binding protein-2 prospectively predict longitudinal elevation of HDL-cholesterol in type 2 diabetes.

INTRODUCTION: Associations of insulin-like growth factor-II (IGF-II) and insulin-like growth factor binding protein-2 (IGFBP-2) with cardiovascular risk have been inadequately studied. We hypothesized that IGF-II and IGFBP-2 associate with longitudinal trends in lipid profiles in type 2 diabetes patients. SUBJECTS AND METHODS: Four hundred and eighty nine subjects with type 2 diabetes (age 27-87 years) from the Salford Diabetes Cohort were studied. Longitudinal clinical information was extracted for an eight-year period (2002-2009) from an integrated electronic dataset of primary care and hospital data. RESULTS: There were 294 male subjects and mean age was 62.9 years. At baseline, IGF-II concentration was 602 ng/mL. HDL cholesterol at baseline was associated with log-IGF-II concentration in a model adjusted for age, gender, baseline body-mass index (BMI), estimated glomerular filtration rate (eGFR) and lipid-lowering therapy. IGFBP-1 and IGFBP-2 were associated with high HDL-cholesterol. A higher circulating IGF-II concentration at baseline was also associated with longitudinal increase in HDL-cholesterol in mixed-effects regression analyses independent of IGF-I, IGFBP-1, IGFBP-2, IGFBP-3, age, gender, eGFR, BMI and lipid-lowering therapy. Log-transformed baseline concentrations of IGFBP-1 and IGFBP-2 were also associated with longitudinal elevation in HDL-cholesterol. No association was observed for IGF-II or IGFBP-2 with longitudinal LDL cholesterol trends. CONCLUSION: Our analyses based on 'real world' data demonstrate that higher baseline IGF-II and IGFBP-2 predict increased HDL concentration over time, implicating IGF-II in modulation of circulating HDL-cholesterol concentrations.

Atorvastatin administration is associated with dose-related changes in IGF bioavailability.

OBJECTIVE: IGF levels, their binding proteins (IGFBPs) and high-dose statin therapy have been linked to the development of diabetes. We aimed to identify whether atorvastatin caused dose-related changes in IGF proteins. DESIGN AND METHODS: We measured IGF1, IGF2, IGFBP1 and IGFBP3 concentrations at baseline, 6 and 12 months in Protection Against Nephropathy in Diabetes with Atorvastatin trial participants with type 2 diabetes randomised to 10 mg (n=59) vs 80 mg (n=60) of atorvastatin (n=119; mean (S.D.): age 64 (10) years; 83% male; HbA1c 61 (10) mmol/mol; blood pressure 131/73 mmHg). RESULTS: Atorvastatin was associated with overall reductions in circulating IGF1, IGF2 and IGFBP3 concentrations (P<0.05 for all changes). The adjusted mean (95% CI) between-group differences that indicate dose-related changes in IGF proteins were not significant for IGF1: -3 (-21 to 14) ng/ml; IGF2: -23 (-65 to 18) ng/ml and IGFBP3: -0.34 (-0.71 to 0.03) µg/ml, negative values indicating numerically greater lowering with high dose. The IGFBP1 concentration did not change with atorvastatin therapy overall but the adjusted mean (95% CI) between-group difference indicating a dose-related change in log IGFBP1 was highly significant -0.41 (-0.69 to 0.13, P=0.004). CONCLUSION: IGF1, IGF2 and IGFBP3 concentrations decreased following atorvastatin therapy. A differential effect of low- vs high-dose atorvastatin on IGFBP1 concentrations was observed with likely implications for IGF bioavailability. The dose-related differential impact of atorvastatin treatment on concentration of IGF proteins merits investigation as a mechanism to explain the worsening of glucose tolerance with statin therapy.

IGFBP2 is a biomarker for predicting longitudinal deterioration in renal function in type 2 diabetes.

OBJECTIVE: Insulin-like growth factors are implicated in the development of diabetic nephropathy. IGF-binding protein 2 (IGFBP2) and IGF2 are expressed in the kidney, but their associations with diabetic nephropathy are unclear. We therefore tested the hypothesis that circulating levels of IGF2 and IGFBP2 predict longitudinal renal function in individuals with type 2 diabetes. DESIGN AND METHODS: IGFBP2 and IGF2 measurements were performed in 436 individuals (263 males) with type 2 diabetes. Linear mixed-effect regression analysis was used to model the relationship between plasma IGFBP2 concentration and longitudinal changes in estimated glomerular filtration rate (eGFR) over an 8-year period. Analyses were also performed for IGF1, IGF2, IGFBP1 and IGFBP3 concentrations as predictors of longitudinal renal outcomes. RESULTS: High IGFBP2 concentration at baseline was associated with a decreased eGFR over an 8-year period (ß=-0.02, (95% confidence interval -0.03 to -0.01), P<0.001). High IGFBP1, IGFBP2 and IGFBP3 were also associated with low baseline eGFR concentration. CONCLUSION: This study demonstrates that IGFBP2 is a predictor of longitudinal deterioration of renal function in type 2 diabetes.

The effect of atorvastatin on serum lipoproteins in acromegaly.

OBJECTIVE: Acromegaly is associated with long-term adverse effects on cardiovascular mortality and morbidity. Reducing growth hormone secretion improves well-being and symptoms, but may not significantly improve the lipoprotein profile. An additional approach to cardiovascular risk reduction in acromegaly may therefore be to target lipoprotein metabolism directly. In this study we investigated the effect of statin treatment. DESIGN: Double blind, placebo-controlled, crossover study of the effects on circulating lipoproteins of atorvastatin 10 mg daily vs. placebo. Each treatment was given for 3 months in random order. SUBJECTS: Eleven patients with acromegaly. MEASUREMENTS: Lipids, lipoproteins, apolipoproteins, enzyme activity and calculated cardiovascular risk. RESULTS: Atorvastatin treatment compared to placebo resulted in a significant decrease in serum cholesterol (5.85 +/- 1.04 mmol/l vs. 4.22 +/- 0.69 mmol/l; mean +/- SD; P < 0.001), low-density lipoprotein (LDL) cholesterol (2.95 +/- 1.07 mmol/l vs. 1.82 +/- 0.92 mmol/l; P < 0.001), very low-density lipoprotein (VLDL) cholesterol (0.31 (0.21-0.47) mmol vs. 0.23 (0.13-0.30) mmol/l median (interquartile range); P < 0.05), apolipoprotein B (111 +/- 28 mg/dl vs. 80 +/- 18 mg/dl; P < 0.001), and calculated coronary heart disease risk (6.8 (3.3-17.9) vs. 2.8 (1.5-5.7)% over next 10 years; P < 0.01). Serum triglyceride was 1.34 (1.06-1.71) mmol/l on placebo and 1.14 (0.88-1.48) mmol/l on atorvastatin (ns). HDL cholesterol, apolipoprotein A1 and Lp(a) concentrations and cholesteryl ester transfer protein and lecithin: cholesterol acyl transferase activities were also not significantly altered. CONCLUSION: Atorvastatin treatment was safe, well tolerated and effective in improving the atherogenic lipoprotein profile in acromegaly.

Abrogation of insulin-like growth factor-I (IGF-I) and insulin action by mevalonic acid depletion: synergy between protein prenylation and receptor glycosylation pathways.

The vasculoprotective effects of hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors (statins) correlate with cholesterol lowering. HMG-CoA reductase inhibitors also disrupt cellular processes by the depletion of isoprenoids and dolichol. Insulin and insulin-like growth factor (IGF) signaling appear particularly prone to such disruption as intracellular receptor processing requires dolichol for correct N-glycosylation, whereas downstream signaling through Ras requires the appropriate prenylation (farnesol). We determined how HMG-CoA reductase inhibition affected the mitogenic effects of IGF-I and metabolic actions of insulin in 3T3-L1 cells and examined the respective roles of receptor glycosylation and Ras prenylation. IGF-I- and insulin-induced proliferation was significantly reduced by all statins tested, although cerivastatin (10 nm) had the greatest effect (p < 0.005). Although inhibitors of Ras prenylation induced similar results (10 microm FTI-277 89% +/- 7.4%, p < 0.01), the effect of HMG-CoA reductase inhibition could only be partially reversed by farnesyl pyrophosphate refeeding. Treatment with statins resulted in decreased membrane expression of receptors and accumulation of proreceptors, suggesting disruption of glycosylation-dependent cleavage. Glycosylation inhibitors inhibited IGF-I-induced proliferation (tunicamycin p < 0.005, castanospermine p < 0.01, deoxymannojirimycin p < 0.01). High concentrations of statin were necessary to impair insulin-mediated glucose uptake (300 nm = 33% +/- 12% p < 0.05), and this process was not effected by farnesyl transferase inhibition. Gycosylation inhibitors mimicked the effect of statin treatment (tunicamycin p < 0.001, castanospermine p < 0.05, deoxymannojirimycin p < 0.05), and there was insulin proreceptor accumulation. These data imply that HMG-CoA reductase inhibitors disrupt IGF-I signaling by combined effects on Ras prenylation and IGF receptor glycosylation, whereas insulin signaling is only affected by disrupted receptor glycosylation.

A substitution model of dietary manipulation is an effective means of optimising lipid profile, reducing C-reactive protein and increasing insulin-like growth factor-1.

There are two key methods in which fat intake may be manipulated; the 'substitution model' and the 'reduction model'. However insufficient information is known about the mechanisms of dietary fat reduction in individuals who have successfully reduced their fat intake, to be clear as to which strategy offers the greatest chance of success. Our objective was to ascertain the most effective dietary intervention for improving cardiovascular risk profile. Eighty female volunteers (high fat consumers) were recruited. Each subject was randomly allocated into one of the following groups. Substitution of high-fat foods was made with reduced-fat products, by the reduction of high-fat foods, by a combination of substitution and reduction strategies, or no advice was given. Each intervention lasted 3 months. Anthropometric measures and fasting blood samples were taken at baseline and follow-up. The substitution intervention resulted in weight loss (mean -1.4 (95 % CI -2.4, -0.2) kg) and reduced percentage body fat (mean -1.3 (95% CI -2.0, -0.5)%). There was no significant weight change with the other interventions. Fasting triacylglycerols (-0.2 (SEM 0.07) mm; P=0.04), cholesterol and C-reactive protein (CRP) levels (0.8 (SEM 0.2) mg/l; P=0.04) fell with the substitution intervention, but not with the other interventions. Insulin-like growth factor-1 increased with both substitution and reduction (P=0.02). There was no significant change in fasting insulin or glucose with any intervention. The substitution model of dietary intervention is effective even over a relatively short interval of time in reducing fasting total cholesterol, triacylglycerols and CRP. Although the group size for the present study was small and involved females only, it has significant implications for population intervention strategies.