Insulin resistance is associated with decreased circulating mannan-binding lectin concentrations in women with polycystic ovary syndrome

High MBL-expressing genotypes are associated with deterioration in renal function in type 2 diabetes

Introduction

Accumulating evidence support that mannan-binding lectin (MBL) is a promising prognostic biomarker for risk-stratification of diabetic micro- and macrovascular complications. Serum MBL levels are predominately genetically determined and depend on MBL genotype. However, Type 1 diabetes (T1D) is associated with higher MBL serum levels for a given MBL genotype, but it remains unknown if this is also the case for patients with T2D. In this study, we evaluated the impact of MBL genotypes on renal function trajectories serum MBL levels and compared MBL genotypes in newly diagnosed patients with T2D with age- and sex-matched healthy individuals. Furthermore, we evaluated differences in parameters of insulin resistance within MBL genotypes.

Methods

In a cross-sectional study, we included 100 patients who were recently diagnosed with T2D and 100 age- and sex-matched individuals. We measured serum MBL levels, MBL genotype, standard biochemistry, and DEXA, in all participants. A 5-year clinical follow-up study was conducted, followed by 12-year data on follow-up biochemistry and clinical status for the progression to micro- or macroalbuminuria for the patients with T2D.

Results

We found similar serum MBL levels and distribution of MBL genotypes between T2D patients and healthy individuals. The serum MBL level for a given MBL genotype did not differ between the groups neither at study entry nor at 5-year follow-up. We found that plasma creatinine increased more rapidly in patients with T2D with the high MBL expression genotype than with the medium/low MBL expression genotype over the 12-year follow-up period (p = 0.029). Serum MBL levels did not correlate with diabetes duration nor with HbA1c. Interestingly, serum MBL was inversely correlated with body fat percentage in individuals with high MBL expression genotypes both at study entry (p=0.0005) and 5-years follow-up (p=0.002).

Discussion

Contrary to T1D, T2D is not per se associated with increased MBL serum level for a given MBL genotype or with diabetes duration. Serum MBL was inversely correlated with body fat percentage, and T2D patients with the high MBL expression genotype presented with deterioration of renal function.

Extreme insulin resistance during pregnancy: a therapeutic challenge

SUMMARY

During pregnancy, maternal tissues become increasingly insensitive to insulin in order to liberate nutritional supply to the growing fetus, but occasionally insulin resistance in pregnancy becomes severe and the treatment challenging. We report a rare and clinically difficult case of extreme insulin resistance with daily insulin requirements of 1420 IU/day during pregnancy in an obese 36-year-old woman with type 2 diabetes (T2D) and polycystic ovary syndrome (PCOS). The woman was referred to the outpatient clinic at gestational week 12 + 2 with a hemoglobin A1c (HbA1c) at 59 mmol/mol. Insulin treatment was initiated immediately using Novomix 30, and the doses were progressively increased, peaking at 1420 units/day at week 34 + 4. At week 35 + 0, there was an abrupt fall in insulin requirements, but with no signs of placental insufficiency. At week 36 + 1 a, healthy baby with no hypoglycemia was delivered by cesarean section. Blood samples were taken late in pregnancy to search for causes of extreme insulin resistance and showed high levels of C-peptide, proinsulin, insulin-like growth factor (IGF-1), mannan-binding-lectin (MBL) and leptin. CRP was mildly elevated, but otherwise, levels of inflammatory markers were normal. Insulin antibodies were undetectable, and no mutations in the insulin receptor (INSR) gene were found. The explanation for the severe insulin resistance, in this case, can be ascribed to PCOS, obesity, profound weight gain, hyperleptinemia and inactivity. This is the first case of extreme insulin resistance during pregnancy, with insulin requirements close to 1500 IU/day with a successful outcome, illustrating the importance of a close interdisciplinary collaboration between patient, obstetricians and endocrinologists.

LEARNING POINTS

This is the first case of extreme insulin resistance during pregnancy, with insulin requirements of up to 1420 IU/day with a successful outcome without significant fetal macrosomia and hypoglycemia. Obesity, PCOS, T2D and high levels of leptin and IGF-1 are predictors of severe insulin resistance in pregnancy. A close collaboration between patient, obstetricians and endocrinologists is crucial for tailoring the best possible treatment for pregnant women with diabetes, beneficial for both the mother and her child.

Changes in insulin sensitivity and insulin secretion during pregnancy and post partum in women with gestational diabetes

INTRODUCTION

The metabolic abnormalities underlying gestational diabetes mellitus (GDM) include increased insulin resistance and beta cell defects, but it is essential to clarify how insulin resistance and insulin secretion develop post partum in order to decide when and how to screen for type 2 diabetes. The purpose of the present study was to characterize and compare changes in insulin sensitivity, insulin secretion and hormonal status around parturition and 6 months post partum in women with gestational diabetes.

RESEARCH DESIGN AND METHODS

A longitudinal experimental study was performed at Aarhus University Hospital, Denmark. Eight women with GDM were examined at three identical visits: in late pregnancy (LP) between gestational age 34+0 and 36+6, early post partum (EPP) between 12 and 34 days post partum, and late post partum (LPP) 6 months post partum. An intravenous glucose tolerance test was performed, followed by a hyperinsulinemic euglycemic clamp. Blood samples were collected to assess metabolic, hormonal and inflammatory markers at each visit.

RESULTS

First and second phase insulin secretion and C-peptide concentrations were higher in late pregnancy than post partum (p<0.001). Insulin sensitivity index (ISI) was different at all three visits: ISI_LP=0.03±0.004, ISI_EPP=0.09±0.008 and ISI_LPP=0.07±0.008) (p<0.001). Also, significant changes in lipids, leptin, glucagon, growth hormone and insulin-like growth factor-1 were seen when comparing the visits.

CONCLUSIONS

Insulin sensitivity improves immediately after delivery in women with GDM but seems to deteriorate within the first 6 months post partum. Our findings underline the importance of having an increased awareness of the profound risk of developing type 2 diabetes after GDM.

TRIAL REGISTRATION NUMBER

NCT02770079.

Elevated Serum Mannose Levels as a Marker of Polycystic Ovary Syndrome

Background: Recent reports have highlighted the role of monosaccharide biosynthesis in the pathogenesis of polycystic ovary syndrome (PCOS), suggesting that these processes may serve as a biomarker in PCOS. Mannose is the main monosaccharide for protein glycosylation in mammals; however, the correlation between mannose and PCOS remains largely unknown. Materials and Methods: A total of 132 Chinese Han women were recruited at Shengjing Hospital of China Medical University. Mannose levels were measured in serum samples collected from 71 patients with PCOS (29 lean, 42 obese) and 61 control subjects (28 lean, 33 obese). Receiver operating characteristics (ROC) curves were prepared to compare the diagnostic performance of mannose and hormonal parameters, individually or in combination. Multivariate logistic regression analysis was used to assess whether serum mannose levels were associated with PCOS after adjusting for other co-variables. Results: We showed that serum mannose levels were significantly increased in PCOS patients compared with control subjects regardless of obese status, and hyperandrogenic PCOS patients had higher serum mannose levels than normo-androgenic PCOS and control subjects. In addition, serum mannose levels were significantly correlated with serum androgen levels. Mannose had an area under the curve (AUC) of 73% at a cutoff value of 225.79 ng/mL with a sensitivity of 66.2% and specificity of 73.8% for predicting PCOS. There were no differences between mannose, total testosterone, free testosterone, or dehydroepiandrosterone sulfate in the reliability of predicting PCOS using the method outlined by Hanley and McNeil. Combining mannose and total testosterone resulted in a higher AUC of 83.3%, and had moderate sensitivity (78.9%) and specificity (77%) for predicting PCOS. The positive and negative predictive values were 80% and 75.8%, respectively. Multivariate logistic regression revealed that higher serum mannose levels were strongly associated with an increased risk of PCOS (P = 0.016; odds ratio, 5.623; 95% confidence interval, 1.371-23.070). Conclusion: Taken together, substantially elevated serum mannose levels are significantly associated with PCOS, highlighting the importance of further research into the role of mannose in the pathogenesis of PCOS.

The complement system is dysfunctional in metabolic disease: Evidences in plasma and adipose tissue from obese and insulin resistant subjects

The relationship among chronic low-grade inflammation, insulin resistance and other obesity-associated metabolic disturbances is increasingly recognized. The possible mechanisms that trigger these immunologic alterations remain to be fully understood. The complement system is a crucial element of immune defense system, being important in the activation of innate and adaptative immune response, promoting the clearance of apoptotic and damaged endogenous cells and participating in processes of tissue development, degeneration, and regeneration. Circulating components of the complement system appear to be dysregulated in obesity-associated metabolic disturbances. The activation of the complement system is also evident in adipose tissue from obese subjects, in association with subclinical inflammation and alterations in glucose metabolism. The possible contribution of some components of the complement system in the development of insulin resistance and obesity-associated metabolic disturbances, and the possible role of complement system in adipose tissue physiology is reviewed here. The modulation of the complement system could constitute a potential target in the pathophysiology and therapy of obesity and associated metabolic disease.

Mannose-binding lectin is required for the effective clearance of apoptotic cells by adipose tissue macrophages during obesity

Obesity is accompanied by the presence of chronic low-grade inflammation manifested by infiltration of macrophages into adipose tissue. Mannose-binding lectin (MBL), a soluble mediator of innate immunity, promotes phagocytosis and alters macrophage function. To assess the function of MBL in the development of obesity, we studied wild-type and MBL(-/-) mice rendered obese using a high-fat diet (HFD). Whereas no gross morphological differences were observed in liver, an HFD provoked distinct changes in the adipose tissue morphology of MBL(-/-) mice. In parallel with increased adipocyte size, MBL(-/-) mice displayed an increased influx of macrophages into adipose tissue. Macrophages were polarized toward an alternatively activated phenotype known to modulate apoptotic cell clearance. MBL deficiency also significantly increased the number of apoptotic cells in adipose tissue. Consistent with these observations, recombinant MBL enhanced phagocytic capacity of the stromal vascular fraction isolated from adipose tissue and modulated uptake of apoptotic adipocytes by macrophages. Despite changes in macrophage abundance and polarity, the absence of MBL did not affect systemic insulin resistance. Finally, in humans, lower levels of circulating MBL were accompanied by enhanced macrophage influx in subcutaneous adipose tissue. We propose a novel role for MBL in the recognition and clearance of apoptotic adipocytes during obesity.

High-Sensitivity C-Reactive Protein in Patients with Polycystic Ovary Syndrome

Objective: To assess the inflammation evaluated by high sensitivity C ReactiveProtein (hsCRP) in women with polycystic ovary syndrome (PCOS) compared withhealthy women without PCOS. Methods: This was a retrospective, case control,observational study. The study group included 31 patients with PCOS and 29 healthypatients matched for age and body mass index (BMI) but without PCOS (controlgroup). PCOS was diagnosed using Rotterdam criteria. Results: Patients with PCOShad higher mean hsCRP levels compared with healthy controls: 3.89±2.75 mg/l inPCOS group and 2.61±1.81 mg/l in the control group, p=0.04. The difference was nolonger significant after adjustment for BMI. In the PCOS group hsCRP waspositively correlated with BMI, waist circumference, visceral fat area, body fat massand glycated hemoglobin (HbA1c). Conclusion: hsCRP levels are increased inpatients with PCOS and are correlated with obesity, fat accumulation and not withthe presence of PCOS per se.

Meta-analysis of cardiovascular disease risk markers in women with polycystic ovary syndrome

BACKGROUND

The relation between polycystic ovary syndrome (PCOS) and cardiovascular disease (CVD) remains unclear. In an attempt to provide high-quality evidence on the relation between PCOS and CVD, relevant literature for CVD risk markers [C-reactive protein (CRP), homocysteine (Hcy), tumor necrosis factor-alpha (TNF-α), plasminogen activator inhibitor-1 (PAI-1), lipoprotein (a) [Lp(a)], advanced glycation end-products (AGEs), vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), asymmetric dimethylarginine (ADMA), endothelin-1 (ET-1) and fibrinogen] in women with PCOS was reviewed and analyzed.

METHODS

A systematic search was conducted electronically using specific eligibility criteria. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated and combined appropriately. To ensure synthesis of the best available evidence, sensitivity analyses were performed. RESULTS A total of 130 data sets were included in 11 different outcomes, involving 7174 and 5076 CVD markers in women with PCOS and controls, respectively. Women with PCOS demonstrated significantly elevated CRP [WMD (95% CI) 0.99 (0.77-1.21)], Hcy [2.25 (1.46-3.03)], PAI-1 antigen [16.96 (7.25-26.28)], PAI-1 activity [0.71 (0.18-1.23)], VEGF [1.72 (0.96-2.48)], ADMA [0.19 (0.08-0.3)], AGEs [3.91 (2.36-5.45)] and Lp(a) [0.81 (0.58-1.04)] concentrations compared with controls, yet with significant between-study heterogeneity. Borderline significance (not robust in the sensitivity analyses) was detected for TNF-α [0.75 (0.07-1.44)], ET-1 [1.06 (0.52-1.59)] and fibrinogen [0.20 (0.01-0.39)], whereas no difference was detected for IL-6 [0.71 (-0.16 to 1.59)]. CONCLUSIONS Women with PCOS have increased serum concentrations of CVD risk markers compared with controls. Whether this apparent risk is translated into increased incidence of CVD in later life remains to be elucidated.

Circulating inflammatory markers in polycystic ovary syndrome: a systematic review and metaanalysis

OBJECTIVE

To perform a review and metaanalysis of the studies evaluating the status of serum inflammatory markers in women with polycystic ovary syndrome (PCOS).

DESIGN

Systematic review and metaanalysis of articles published in English before January 2010 and identified using the PubMed search engine.

SETTING

Academic hospital.

PATIENT(S)

Women with PCOS and appropriate controls.

INTERVENTION(S)

Measurement of serum concentrations of inflammatory markers by high-sensitivity techniques.

MAIN OUTCOME MEASURE(S)

Metaanalyses of the mean difference in serum C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) concentrations among patients with PCOS and appropriate controls, applying random-effects models to limit interstudy variability, and using appropriate estimates of evidence dissemination bias.

RESULT(S)

Metaanalysis of the 31 articles meeting inclusion criteria showed that circulating CRP was 96% higher in women with PCOS compared to controls (95% confidence interval, 71%-122%; z = 7.32) without evidence of dissemination bias (Egger's regression intercept, 0.45; 95% confidence interval, -2.30 to 3.21). These findings persisted after excluding five studies with mismatches in body mass, frequency of obesity, or both, between women with PCOS and controls. Metaanalyses involving 10 studies of IL-6, and nine studies of TNF-α revealed no statistically significant differences between PCOS and controls.

CONCLUSION(S)

Women with PCOS exhibit an elevation in circulating CRP that is independent of obesity. This finding corroborates existing molecular evidence of the chronic low-grade inflammation that may underpin the pathogenesis of this disorder.