Effect of bariatric surgery on plasma levels of oxidised phospholipids, biomarkers of oxidised LDL and lipoprotein(a).

BACKGROUND: Obesity is associated with adverse cardiovascular outcomes and this is improved following bariatric surgery. Oxidised phospholipids (OxPL) are thought to reflect the pro-inflammatory effects of lipoprotein(a) [Lp(a)], and both are independent predictors of cardiovascular disease. OBJECTIVE: Our study sought to determine the impact of bariatric surgery on OxPL, biomarkers of oxidised LDL (OxLDL) and Lp(a). METHODS: This is a prospective, observational study of 59 patients with severe obesity undergoing bariatric surgery. Blood samples were obtained prior to surgery and at 6 and 12 months after. Sixteen patients attending the tertiary medical weight management clinic at the same centre were also recruited for comparison. Lipid and metabolic blood parameters, OxLDL, OxPL on apolipoprotein B-100 (OxPL-apoB), IgG and IgM autoantibodies to MDA-LDL, IgG and IgM apoB-immune complexes and Lp(a) were measured. RESULTS: Reduction in body mass index (BMI) was significant following bariatric surgery, from median 48 kg/m2 at baseline to 37 kg/m2 at 6 months and 33 kg/m2 at 12 months. OxPL-apoB levels decreased significantly at 12 months following surgery [5.0 (3.2-7.4) to 3.8 (3.0-5.5) nM, p = 0.001], while contrastingly, Lp(a) increased significantly [10.2 (3.8-31.9) to 16.9 (4.9-38.6) mg/dl, p = 0.002]. There were significant post-surgical decreases in IgG and IgM biomarkers, particularly at 12 months, while OxLDL remained unchanged. CONCLUSIONS: Bariatric surgery results in a significant increase in Lp(a) but reductions in OxPL-apoB and other biomarkers of oxidised lipoproteins, suggesting increased synthetic capacity and reduced oxidative stress. These biomarkers might be clinically useful to monitor physiological effects of weight loss interventions.

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.

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.

The use of eGFR and ACR to predict decline in renal function in people with diabetes.

BACKGROUND: There have been few attempts to estimate progression of kidney disease in people with diabetes in a single large population with predictive modelling. The aim of this study was to investigate the rate of progression of chronic kidney disease in people with diabetes according to their estimated glomerular filtration rate (eGFR) and presence of albuminuria. METHODS: Data were collected on all people with diabetes in Salford, UK, where an eGFR could be calculated using the four-variable MDRD formula and urinary albumin-creatinine ratio (uACR) was available. All data between 2001 and 2007 were used in the model. Classification of albuminuria status was based on the average of their first two uACR measurements. A longitudinal mixed effect dynamic regression model was fitted to the data. Parameters were estimated by maximum likelihood. RESULTS: For the analysis of the population, average progression of eGFR, uACR and drug prescribing were available in 3431 people. The regression model showed that in people with diabetes and macroalbuminuria, eGFR declined at 5.7% per annum, while the eGFR of those with microalbuminuria or without albuminuria declined at 1.5% and 0.3% per annum, respectively, independently of age (P < 0.0001). CONCLUSIONS: The longitudinal effect of time on eGFR showed that people with diabetes and macroalbuminuria have an estimated 19 times more rapid decline in renal function compared with those without albuminuria. This study demonstrates that the progression of kidney disease in diabetic people without albuminuria is relatively benign compared with those with albuminuria.

Effects of hormone replacement therapy on insulin-like growth factor (IGF)-I, IGF-II and IGF binding protein (IGFBP)-1 to IGFBP-4: implications for cardiovascular risk.

OBJECTIVE: Hormone replacement therapy (HRT) in postmenopausal women is controversial, with an elevated cardiovascular event rate for combined estrogen-progestogen but no adverse cardiovascular effect and possible cumulative benefit for estrogen alone. Here we measured the effects of differing estrogen/progestogen combinations on the insulin-like growth factor (IGF)/IGF binding protein (IGFBP) system which has been implicated in the pathophysiological mechanisms underlying cardiovascular disease, higher IGFBP-1 levels having been linked with a reduced cardiovascular risk. DESIGN: Oral conjugated equine estrogens (CEE) alone, or in combination with the increasingly androgenic progestogens medroxyprogesterone acetate, desogestrel or norethisterone, were given in a randomized triple crossover fashion to 35 healthy postmenopausal women. Serum concentrations of IGFs and the principal circulating IGFBPs were measured. RESULTS: Circulating IGF-I, IGFBP-3 and IGF-I/IGFBP-3 molar ratio were significantly reduced by CEE. These effects were reversed by progestogens according to their androgenicity. Plasma IGFBP-1 concentration increased from baseline to CEE alone. This rise was opposed by progestogens of increasing androgenicity. IGFBP-2 levels fell and IGFBP-4 increased with CEE, with no further change with addition of progestogens. CEE increased the proportional contribution of IGFBP-1 and IGFBP-4 to total IGFBP binding and decreased the IGFBP-3 contribution. This was reversed by progestogens. CONCLUSION: There are marked changes in molar ratios of the IGFBPs in relation to estrogen/progestogens in HRT. The effect of progestogens on IGF bioavailability could be an important determinant of the longer-term risks of specific HRT preparations by opposing the potentially beneficial effects of CEE alone on cardiovascular risk.