Anemia is associated with an elevated serum level of high-molecular-weight adiponectin in patients with type 2 diabetes independently of renal dysfunction

New Insights into Adiponectin and Leptin Roles in Chronic Kidney Disease

Chronic kidney disease (CKD) is commonly associated with a high burden of comorbidities and poor clinical outcomes. Malnutrition–inflammation–atherosclerosis syndrome is common in the more severe stages of CKD, suggesting a close interplay for these three comorbid conditions. Both malnutrition and obesity are associated with a disturbed adipokine profile and inflammation, contributing to a higher risk of cardiovascular disease (CVD) events. Adiponectin and leptin have important roles in carbohydrate and lipid metabolism, and in the inflammatory process. The effects of adiponectin and leptin alterations in CKD, which are usually increased, and their association with the different comorbidities found in CKD, will be focused on to understand their crosstalk with the risk of CVD events. Nonetheless, although adiponectin and leptin contribute to a higher risk of CVD events, further studies are warranted to fully clarify their roles, especially when different comorbidities exist.

Novel Iron Parameters in Patients with Type 2 Diabetes Mellitus in Relation to Kidney Function

BACKGROUND/AIMS

Anemia of chronic disease is a common feature in diabetes and chronic kidney disease. Hepcidin is the key element involved in iron metabolism; however, studies on new indices of iron status are still ongoing. The aim of the study was to assess novel iron parameters in patients with type 2 diabetes mellitus in relation to kidney function.

METHODS

The study included 80 type 2 diabetic patients and 23 healthy volunteers. Standard laboratory measurements were used to measure the iron status, complete blood count, creatinine, the estimated glomerular filtration rate (eGFR), serum lipids, and brain natriuretic peptides (BNPs). Commercially available kits were used to measure hepcidin-25, the soluble transferrin receptor (sTfR), growth differentiation factor-15 (GDF-15), and hypoxia-inducible factor-1 alpha.

RESULTS

Anemia was present in 65% of the studied patients. The control group was found to have significantly higher hepcidin, sTfR, and GDF-15, and lower hemoglobin and iron. When compared with patients with eGFR values ≥60 mL/min/1.73 m² and <60 mL/min/1.73 m², we found that patients with higher eGFR had higher hemoglobin, ferritin, and HIF-1 alpha, lower BNP, and were younger. We found that levels of HIF-1 alpha are negligible in the studied population and were related to age only in patients with eGFR values ≥60 mL/min/1.73 m².

CONCLUSION

A comprehensive assessment of iron status is rarely performed. Novel biomarkers of iron metabolism are not generally related to kidney function. Whether the assessment of HIF-1 alpha would be a marker of efficient anemia therapy with HIF-prolyl hydroxylase inhibitors is still a matter for further study.

Low serum adiponectin level is associated with better physical health-related quality of life in chronic kidney disease

Hyperadiponectemia is paradoxically associated with renal disease progression and mortality in chronic kidney disease (CKD). Its association with health-related quality of life (HR-QOL) is unknown. This study aimed to verify the association between adiponectin and HR-QOL in Korean pre-dialysis CKD cohort. This cross-sectional study analyzed 1551 pre-dialysis CKD patients from KNOW-CKD (KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease). Participants were categorized into three tertiles (T1–T3) according to adiponectin levels. HR-QOL was assessed using SF-36. High physical component summary (PCS) and mental component summary (MCS) were defined as highest quartile of each score. Multivariate logistic regression was used to analyze odds ratio (OR) and 95% confidence interval (CI) for high PCS and MCS. Prevalence of high PCS were 33.3%, 27.5%, and 17.0% and that of high MCS were 31.7%, 24.8%, and 21.3% for T1, T2, and T3 (both p for trend < 0.001). The adjusted OR [95% CI] of T1 and T2 in reference to T3 were 1.56 [1.09–2.23] and 1.19 [0.85–1.68] for high PCS and 1.19 [0.85–1.68] and 0.94 [0.68–1.29] for high MCS. Serum adiponectin level was inversely associated with physical HR-QOL in Korean pre-dialysis CKD patients. This relationship was independent of various cardiovascular risk factors.

High serum adiponectin is associated with anemia development in chronic kidney disease: The results from the KNOW-CKD study

BACKGROUND

Adiponectin is an adipokine secreted by adipocytes. A low adiponectin level is a significant risk factor of diabetes mellitus and cardiovascular disease. Recent studies have shown that adiponectin is negatively associated with hematopoiesis and predicts the development of anemia in the general population. In chronic kidney disease (CKD) patients, circulating adiponectin level is paradoxically elevated and the role of adiponectin is complex. Therefore, we evaluated the relationship between adiponectin and anemia in these patients.

METHODS

This prospective longitudinal study included 2113 patients from the KNOW-CKD study (KoreaN cohort study for Outcome in patients With CKD), after excluding 125 without data on adiponectin levels. Hemoglobin levels were measured yearly during a mean follow-up period of 23.7 months. Anemia was defined as hemoglobin levels of <13.0 and 12.0 g/dL for men and women, respectively.

RESULTS

Mean patient age was 53.6 ± 12.2 years, and 1289 (61%) were men. The mean estimated glomerular filtration rate (eGFR) was 50.4 ± 30.2 mL min^-1 1.73 m^-2. Serum adiponectin level was inversely associated with body mass index, eGFR, log-transformed C-reactive protein, and positively with Charlson comorbidity index, urine protein to creatinine ratio, and high density lipoprotein cholesterol. In addition, serum adiponectin level was also negatively correlated with hemoglobin level and reticulocyte production index in both men and women. In multivariable linear regression analysis after adjustment of multiple confounders, adiponectin was negatively associated with hemoglobin (men, β = -0.219, P < .001; women, β = -0.09, P = .025). Among 1227 patients without anemia at baseline, 307 newly developed anemia during the follow-up period. In multivariable Cox regression analysis after adjustment of confounders, high adiponectin level was significantly associated with an increased risk of incident anemia (per 1 µg/mL increase, hazard ratio, 1.02; 95% confidence interval 1.01-1.04; P = .001).

CONCLUSIONS

A high serum adiponectin level is independently associated with a low hemoglobin level and predicts the development of anemia in patients with CKD. These findings reveal the potential role of adiponectin in CKD-related anemia.

Synthetic peptides designed to modulate adiponectin assembly improve obesity-related metabolic disorders

BACKGROUND AND PURPOSE

Adiponectin, an adipokine possessing profound insulin-sensitizing and anti-inflammatory properties, is a potent biotherapeutic agent . The trimeric adiponectin subunit assembles into hexameric and functionally important higher molecular weight (HMW) forms, controlled by the endoplasmic reticulum protein 44 (ERp44). Obesity-induced ER stress decreases the HMW form in serum, contributing to the development of insulin resistance and Type 2 diabetes. In this study, a panel of synthetic peptides, designed to target ERp44-adiponectin interactions, were tested for their effects on circulating levels of HMW adiponectin.

EXPERIMENTAL APPROACH

Peptides derived from the ERp44 binding region of adiponectin and immunoglobulin IgM were synthesized with or without a cell-penetrating sequence. Cultures of 3T3-L1 adipocytes were incubated with the peptides for assessing the assembly and secretion of HMW adiponectin. Mice given standard chow or a high-fat diet were treated acutely or chronically, with the peptides to investigate the therapeutic effects on insulin sensitivity and energy metabolism.

RESULTS

The designed peptides interfered with ERp44-adiponectin interactions and modulated adiponectin assembly and release from adipocytes. In particular, IgM-derived peptides facilitated the release of endogenous adiponectin (especially the HMW form) from adipose tissue, enhanced its circulating level and the ratio of HMW-to-total-adiponectin in obese mice. Long-term treatment of mice fed with high-fat diet by IgM-derived peptides reduced the circulating lipid levels and improved insulin sensitivity.

CONCLUSIONS AND IMPLICATIONS

Targeting ERp44-adiponectin interactions with short peptides represents an effective strategy to treat of obesity-related metabolic disorders, such as insulin resistance and Type 2 diabetes.

Management of anemia in patients with diabetic kidney disease: A consensus statement

This consensus statement focuses on the window of opportunity, which exists while treating patients with diabetic kidney disease and anemia.

Hypoadiponectinemia and the presence of metabolic syndrome in patients with chronic kidney disease: results from the KNOW-CKD study

BACKGROUND

In patients with chronic kidney disease, metabolic syndrome has been demonstrated to be the culprit behind diverse complications. Adiponectin is known to have anti-atherogenic and cardio-protective effects. Meanwhile, the relationship between adiponectin and metabolic syndrome in patients with chronic kidney disease has not been clarified. The aim of this study was to elucidate the relationship between adiponectin level and metabolic syndrome in patients with chronic kidney disease.

METHODS

The KoreaN Cohort Study for Outcome in Patients with Chronic Kidney Disease is a cohort study that enrolled subjects with chronic kidney disease throughout South Korea. From February 2011 to July 2014, data were collected from 1332 patients with chronic kidney disease.

RESULTS

The mean age of the patients was 53.5 years and 803 patients (60.7%) were men. The median adiponectin level was 10.7 μg/mL and 585 (44.3%) patients had metabolic syndrome. In multiple linear regression analysis, log adiponectin was positively associated with high-density lipoprotein cholesterol levels (β = 0.006), whereas it was negatively associated with serum albumin (β = -0.284), triglyceride (log β = -0.288), high sensitivity C-reactive protein (log β = -0.058) levels and estimated glomerular filtration rate (β = -0.005). Multiple logistic regression analysis indicated that low adiponectin level was independently associated with a higher risk of metabolic syndrome (per 1 μg/mL increase; odds ratio = 0.953, 95% confidence interval = 0.898-0.970, P < 0.001) after adjustment for multiple confounding factors.

CONCLUSIONS

Hypoadiponectinemia is independently associated with the presence of metabolic syndrome in patients with chronic kidney disease.

Adiponectin, hemoglobin, and cardiovascular risk in an indigenous siberian population

OBJECTIVES

Adipose tissue hypoxia appears to play a role in promoting chronic inflammation and the development of obesity-related cardiovascular and metabolic diseases, yet the underlying mechanisms are not well understood. The aim of the present research is to examine whether adiponectin levels (an adipocyte-derived hormone with anti-inflammatory properties) are inversely correlated with hemoglobin levels in an indigenous Siberian population.

METHODS

The study was conducted among 252 Yakut adults (≥18 years; 135 females) from Berdygestiakh, Sakha Republic, Russia. Measurements included anthropometric dimensions (body mass index [BMI], waist circumference [WC], and percent body fat) and blood levels of hemoglobin and adiponectin.

RESULTS

Yakut females had higher adiponectin concentrations than males (15.1 ± 9.8 vs. 11.7 ± 10.6 µg/ml; P < 0.001), whereas males had higher hemoglobin levels (14.4 ± 1.4 vs. 12.6 ± 1.5 g/dL; P < 0.001). Body composition measures in both sexes were negatively associated with adiponectin and positively associated with hemoglobin. After adjusting for central adiposity and smoking, adiponectin levels were negatively correlated with hemoglobin levels in men (P < 0.05), but not in women (P = 0.511).

CONCLUSIONS

This investigation provides some support for the involvement of hypoxia-related dysregulation of adiponectin associated with obesity and potentially cardiovascular disease. Am. J. Hum. Biol. 28:580-583, 2016. © 2015 Wiley Periodicals, Inc.

Serum Adiponectin and Glomerular Filtration Rate in Patients with Type 2 Diabetes

High serum adiponectin has been increased in several conditions of kidney disease. Only sparse and conflicting results have been reported in patients with type 2 diabetes (T2D), a subgroup of individuals who are at high risk for renal dysfunction. The aim of this study was to fill up this gap of knowledge by investigating such association in a large sample of Italian diabetic patients. The association between serum adiponectin levels and estimated glomerular filtration rate (eGFR by Chronic Kidney Disease-Epidemiology Collaboration CKD-EPI equation) was investigated in 1,243 patients with T2D from two cross-sectional Italian studies: 878 from San Giovanni Rotondo (SGR) and 365 from Foggia (FG). Serum adiponectin was inversely associated with eGFR in SGR [β (standard error, SE) for 1 standard deviation (SD) of adiponectin = -3.26 (0.64)] and in FG [β(SE)=-5.70(1.28)] sample, as well as in the two studies combined [β(SE)=-3.99(0.59)];(p<0.0001 for all). In this combined analysis, the association was still significant after adjusting for sex, smoking habits, body mass index (BMI), waist circumference, diabetes duration, glycated hemoglobin (HbA1c), albumin creatinine ratio (ACR) and anti-hyperglycemic, anti-hypertensive and anti-dyslipidemic treatments [β (SE)= -2.19 (0.59), p = 0.0001]. A stronger association between each SD adiponectin increment and low eGFR was observed among patients with micro-/macro-albuminuria, as compared to those with normo-albuminuria [adjusted β(SE)=-4.42(1.16) ml/min/1.73m² vs. -1.50 (0.67) ml/min/1.73m², respectively; p for adiponectin-by-albuminuric status = 0.022]. For each adiponectin SD increment, the odds of having eGFR < 60 ml/min/1.73m² increased by 41% (odds ratio, OR = 1.41; 95% confidence interval, CI 1.21–1.64) in SGR sample, 53% (OR = 1.53; 95% CI 1.21–1.94) in FG sample, and 44% (OR = 1.44; 95%CI 1.27–1.64) in the two studies considered together (p<0.0001 for all). In the combined sample, further adjustment for the above mentioned covariates did not change the observed association (OR = 1.36; 95%CI 1.16–1.60; p<0.0001). Our study, so far the largest addressing the relationship between serum adiponectin and GFR in T2D, strongly suggests that the paradoxical inverse association, previously reported in different clinical sets, is also observed in diabetic patients. Further studies are needed to unravel the biology underlying this counterintuitive relationship.

High serum adiponectin is associated with low blood haemoglobin in elderly men: the Swedish MrOS study

OBJECTIVES

Blood haemoglobin (Hb) concentration declines in elderly men, whilst the level of the adipocyte-derived protein adiponectin increases with age. The association between erythropoiesis and adiponectin in elderly men is unclear. The aim of this study was to determine whether adipokines such as adiponectin and leptin are associated with anaemia and Hb concentration in elderly community-dwelling men.

DESIGN AND SETTING

The Gothenburg part of the population-based Swedish Osteoporotic Fractures in Men (MrOS) cohort (n = 1010; median age 75.3 years, range 69-81).

MAIN OUTCOME MEASURES

We investigated the associations between levels of adiponectin and Hb before and after adjusting for potential confounders [i.e. age, body composition, erythropoietin (EPO), total oestradiol, leptin, cystatin C and iron and B vitamin status].

RESULTS

In these elderly men, age was negatively associated with Hb (r = -0.12, P < 0.001) and positively associated with adiponectin level (r = 0.13, P < 0.001). In age-adjusted partial correlations, Hb and adiponectin levels were negatively correlated (r = -0.20, P < 0.001); this association remained significant after multivariable adjustment for age, body composition, EPO, fasting insulin, sex hormones, leptin and ferritin. Age-adjusted mean adiponectin concentrations were significantly higher in anaemic men (66/1005; Hb <130 g L(-1) ) compared to nonanaemic men (14.0 vs. 11.7 μg mL(-1) , P < 0.05). In multivariate analysis, adiponectin together with EPO, total oestradiol, insulin, albumin, transferrin saturation, HDL cholesterol, cystatin C, total body fat mass and free thyroxine, but not leptin, explained 35% of the variation in Hb level. These results remained essentially unchanged after exclusion of men with diabetes.

CONCLUSIONS

Serum adiponectin, but not leptin, was negatively and independently associated with Hb. This finding suggests a possible role of adiponectin in the age-related decline in Hb level observed in apparently healthy elderly men.

Predicting the emergence of anemia--A large cohort study

BACKGROUND AND OBJECTIVES

We aimed to find predictors for development of anemia in a large cohort of adults.

PATIENTS AND METHODS

Cohort study of a large health database from a screening center at the Rabin Medical Center in Israel, between the years 2000-2013. We asked which variables, known at the first visit, would predict anemia at the last visit. Multivariable analysis was conducted using stepwise logistic regression analysis. Odds ratios (ORs) for anemia with 95% confidence intervals (CIs) were calculated.

RESULTS

Our cohort included 10,577 people. At baseline 4.4% were diagnosed with anemia and excluded. Therefore, 10,093 subjects, with a mean age of 42.3 ± 9 years comprised our study sample. At the end of follow-up of 4.7 ± 3.1 years, 307 developed anemia (3%). In men, independent predictors for development of anemia were diabetes mellitus (OR 3.00, 95% CI 1.41-6.39), age (OR 1.03, 95% CI 1.03-1.05, for 1 year increment), low MCV (OR 0.92, 95% CI 0.89-0.96, for every 1 fL unit increment) and elevated platelet count (OR 1.004, 95% CI 1.00-1.01 for 1000/μL unit increment). For women, high total serum protein level was a strong predictor for anemia (OR 3.44, 95% CI 2.33-5.08 for 1mg/dL increment) as well as low triglycerides (OR 0.996, 95% CI 0.993-1.000 for 1mg/dL increment).

CONCLUSIONS

Subgroups who are prone to develop anemia include men with diabetes, and women with an elevated serum protein level and low triglycerides.

Higher levels of adiponectin in vascular endothelial cells are associated with greater brachial artery flow-mediated dilation in older adults

Adiponectin, an adipocyte-derived protein, exerts anti-atherosclerotic effects on the vascular endothelium. Recently adiponectin protein has been reported in murine vascular endothelial cells, however, whether adiponectin is present in human vascular endothelial cells remains unexplored. We sought to examine 1) adiponectin protein in vascular endothelial cells collected from older adults free of overt cardiovascular disease; 2) the relation between endothelial cell adiponectin and in vivo vascular endothelial function; and 3) the relation between endothelial cell adiponectin, circulating (plasma) adiponectin and related factors. We measured vascular endothelial function (brachial artery flow-mediated dilation using ultrasonography), vascular endothelial cell adiponectin (biopsy coupled with quantitative immunofluorescence) and circulating adiponectin (Mercodia, ELISA) in older, sedentary, non-smoking, men and women (55-79 years). We found that higher endothelial cell adiponectin was related with greater flow-mediated dilation (r = 0.43, P < 0.05) and greater flow-mediated dilation normalized for shear stress (r = 0.56, P < 0.01), but was not related with vascular smooth muscle responsiveness to nitric oxide (r = 0.04, P = 0.9). Vascular endothelial cell adiponectin was not related with circulating adiponectin (r = -0.14, P = 0.6). Endothelial cell and circulating adiponectin were differentially associated with adiposity, metabolic and other factors, but both were inversely associated with renal function (r = 0.44 to 0.62, P ≤ 0.04). In conclusion, higher endothelial cell adiponectin levels are associated with higher vascular endothelial function, independent of circulating adiponectin levels in older adults.

Anemia and reduced renal function are independent predictors of elevated serum adiponectin in elderly women

AIM

Although higher adiponectin levels predict a low risk of type 2 diabetes, elevated adiponectin levels predict higher mortality in older persons.

METHODS

We examined the associations of adiponectin with anthropometric, metabolic and hematological variables and renal function in 361 community-dwelling elderly women aged 76±8. Renal function was assessed using the estimated glomerular filtration rate (eGFR).

RESULTS

By univariate analysis, hemoglobin (r=-0.307, p<0.001) and creatinine-based eGFR (r=-0.121, p<0.05) were inversely associated with adiponectin. After adjustment for percentage body fat, HDL cholesterol and serum leptin, hemoglobin and creatinine-based eGFR remained independent predictors of adiponectin (standardized β coefficient=-0.248, p<0.0001, and -0.101, p=0.03, respectively). A similar but stronger relationship was observed between adiponectin and cystatin C-based eGFR (standardized β coefficient=-0.180, p=0.02). Elderly women with anemia had higher serum adiponectin than those without anemia (17.7±9.1 vs. 14.1±7.0 µg/mL, p=0.001). Women with creatinine-based eGFR <45 mL/min/1.73 m2 (19.2±10.6 µg/mL) had higher adiponectin than those with eGFR ≥45 -< 60 mL/min/1.73 m(2) (14.4±6.9 µg/mL) and those with eGFR ≥60 mL/min/1.73 m(2) (14.5±7.4 µg/mL, p<0.05).

CONCLUSIONS

We conclude that hemoglobin and eGFR are independently associated with serum adiponectin in community-dwelling elderly women. Anemia and reduced renal function may contribute to elevated adiponectin levels in the elderly and may represent important confounders of the relationship between elevated adiponectin and mortality in this population.

Adiponectin in renal disease--a review of the evidence as a risk factor for cardiovascular and all-cause mortality

Adiponectin, an adipokine, was discovered in 1995. The initial evidence led to the study of adiponectin as a determinant of insulin sensitivity and blood glucose levels. The literature then evolved to reports of the inverse association of adiponectin with incident Type 2 diabetes mellitus and coronary heart disease. Shortly thereafter, reports of a positive association with heart failure and mortality appeared and were replicated. We review here the basic science evidence and clinical studies of the role of renal function and kidney disease as a determinant of adiponectin.

Total and HMW adiponectin is independently associated with B-type natriuretic peptide and anemia in chronic hemodialysis patients

OBJECTIVE

A number of vasculo-protective roles have been reported for adiponectin. In contrast, higher, rather than lower, plasma adiponectin levels are associated with an increased risk of cardiovascular disease and mortality in patients undergoing hemodialysis (HD). The mechanisms by which high adiponectin levels are associated with adverse outcome are unclear.

METHODS

This study measured the level of total and high molecular weight (HMW) adiponectins in 70 patients with HD patients (age: 65.2±8.6 years, man/woman: 30/40), and examined the association between adiponectins, metabolic and echocardiographic parameters.

RESULTS

Women had a significantly higher total, HMW levels and HMW to total ratio than men. The levels of total and HMW adiponectin were positively correlated with those of HDL-cholesterol and B-type natriuretic peptide (BNP) levels, and negatively associated with body mass index (BMI), triglyceride, high sensitive-C reactive protein (CRP) and hemoglobin levels. A multiple linear regression analysis showed that HMW adiponectin had an independent association with BMI (β=-0.270, p=0.003), HDL-cholesterol (β=0.356, p<0.001), hemoglobin (β=-0.180, p=0.034) and BNP (β=0.200, p=0.014) as total did adiponectin.

CONCLUSION

Anemia and BNP levels had independent influence on the total and HMW adiponectin levels in chronic HD patients.

Elevation of serum high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension: association with arterial stiffness and hypercoagulability

AIM

Orthostatic hypotension is a hallmark of diabetic autonomic neuropathy and is associated with increased mortality. The serum level of adiponectin is elevated in patients with heart failure or renal failure. In the present study, we measured serum levels of total and high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension. We also investigated the relationship between the presence of orthostatic hypotension and various clinical variables in patients with Type 2 diabetes.

METHODS

We studied 105 patients with Type 2 diabetes. Orthostatic hypotension was defined as a decrease of 20 mmHg or more in systolic blood pressure and/or 10 mmHg in diastolic blood pressure when blood pressure was measured for 3 min while standing. The brachial-ankle pulse-wave velocity was also measured as an index of arterial stiffness.

RESULTS

Orthostatic hypotension was found in 30 patients with diabetes (28.6%). The haematocrit and estimated glomerular filtration rate were significantly lower in patients with orthostatic hypotension than in those without it. Brachial-ankle pulse-wave velocity and serum total and high molecular weight adiponectin were significantly higher in patients with orthostatic hypotension than in those without. Furthermore, the high molecular weight/total adiponectin ratio was higher in patients with orthostatic hypotension than in those without and hypertension was more common in patients with orthostatic hypotension. Plasma prothrombin F1 + 2, a coagulation maker, was higher in patients with orthostatic hypotension than in those without, while there were no differences of fibrinolytic markers between the two groups. Multivariate analysis showed that HDL cholesterol, haematocrit, F1 + 2, brachial-ankle pulse-wave velocity and a decline of systolic blood pressure on standing were independent determinants of high molecular weight adiponectin.

CONCLUSIONS

Patients with Type 2 diabetes and orthostatic hypotension had an elevated serum level of high molecular weight adiponectin, which was associated with the simultaneous presence of renal dysfunction, anaemia, arterial stiffness and hypercoagulability.

Novel avenues of drug discovery and biomarkers for diabetes mellitus

Globally, developed nations spend a significant amount of their resources on health care initiatives that poorly translate into increased population life expectancy. As an example, the United States devotes 16% of its gross domestic product to health care, the highest level in the world, but falls behind other nations that enjoy greater individual life expectancy. These observations point to the need for pioneering avenues of drug discovery to increase life span with controlled costs. In particular, innovative drug development for metabolic disorders such as diabetes mellitus becomes increasingly critical given that the number of diabetic people will increase exponentially over the next 20 years. This article discusses the elucidation and targeting of novel cellular pathways that are intimately tied to oxidative stress in diabetes mellitus for new treatment strategies. Pathways that involve wingless, β-nicotinamide adenine dinucleotide (NAD(+)) precursors, and cytokines govern complex biological pathways that determine both cell survival and longevity during diabetes mellitus and its complications. Furthermore, the role of these entities as biomarkers for disease can further enhance their utility irrespective of their treatment potential. Greater understanding of the intricacies of these unique cellular mechanisms will shape future drug discovery for diabetes mellitus to provide focused clinical care with limited or absent long-term complications.

Determinants of serum high molecular weight (HMW) adiponectin levels in patients with coronary artery disease: associations with cardio-renal-anemia syndrome

OBJECTIVE

A low serum adiponectin level is associated with a high incidence of coronary artery disease (CAD) in the healthy population. Paradoxically, serum adiponectin is elevated in patients with severe CAD or chronic heart failure. We investigated the determinants of serum high molecular weight (HMW) adiponectin in patients with CAD.

PATIENTS AND METHODS

We studied 228 consecutive patients with CAD confirmed by angiography. Anemia was defined as a hemoglobin of <13.0 g/dL in men and<12.0 g/dL in women. A high plasma B-type natriuretic-peptide (BNP) was defined as >100 pg/mL. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min for more than 3 months. The patients with CAD were divided into eight groups according to the presence or absence of anemia, high BNP, and/or CKD.

RESULTS

In all 228 patients with CAD, serum HMW adiponectin correlated positively with age, high-density-lipoprotein cholesterol (HDL-C), and BNP, while this parameter showed negative correlations with body mass index, insulin resistance, triglycerides, eGFR, and hemoglobin. Multivariate analysis showed that HDL-C, BNP, gender, and age were independently associated with the HMW adiponectin. Serum HMW adiponectin was lower in CAD patients with than without metabolic syndrome. Serum HMW adiponectin and the HMW/total adiponectin ratio were highest in CAD patients who had anemia, high BNP, and CKD among the groups.

CONCLUSION

In patients with CAD, metabolic syndrome is associated with a lower serum HMW adiponectin, while the presence of anemia, high BNP, and CKD is associated with elevation of the serum HMW adiponectin.

Hemoglobin is associated with serum high molecular weight adiponectin in Japanese community-dwelling persons

AIM

Serum high molecular weight (HMW) adiponectin improves insulin sensitivity, and a decreased level of serum HMW adiponectin has been reported as a risk factor for the development of diabetes and coronary heart disease. This association may be further confounded by the hemoglobin status, which is involved in the development of atherosclerosis.

METHODS

A cross-sectional study was carried out in 2002. Study participants, consisting of 897 men aged 61±14 (mean±standard deviation) years and 1,148 women aged 63±12 years, were randomly recruited from a single community at the time of their annual health examination.

RESULTS

Serum HMW adiponectin levels were lowered dose-dependently with an increased hemoglobin level. Stepwise multiple linear regression analyses for serum HMW adiponectin revealed that the hemoglobin status was independently and significantly associated with serum HMW adiponectin levels as well as sex, age, body mass index (BMI), alcohol consumption, total cholesterol, triglycerides, high density lipoprotein cholesterol, antilipidemic medication, uric acid, serum gamma glutamyltransferase, and insulin resistance. Inclusion of hemoglobin levels in the model further increased the coefficient of determination. In stratified analysis, mean serum HMW adiponectin levels were significantly and similarly decreased as hemoglobin levels increased in men, ages ≥ 65 years, BMI < 23.0 kg/m(2), alcohol drinkers, and lower insulin resistance, and there were significant interactions between the two groups for BMI, alcohol consumption and insulin resistance.

CONCLUSION

Hemoglobin status is inversely associated with serum HMW adiponectin levels in community-dwelling persons, especially those aged ≥ 65 years, BMI < 23.0 kg/m(2), alcohol drinkers, and lower insulin resistance groups.

Relation between serum high molecular weight adiponectin and serum ferritin or prohepcidin in patients with type 2 diabetes

An increase of serum ferritin, an indicator of body iron store, is associated with insulin resistance and with an increased risk of type 2 diabetes in the general population. A low serum adiponectin is also associated with insulin resistance. Recently, hepcidin was identified as a regulator of iron metabolism. We investigated whether serum adiponectin was associated with serum ferritin or prohepcidin, a precursor of hepcidin, in healthy subjects and patients with type 2 diabetes. We studied 65 healthy subjects and 104 patients with type 2 diabetes. A serum ferritin concentration ≥ 300 ng/ml for men or ≥ 150 ng/ml for women was defined as hyperferritinemia. Serum ferritin was significantly higher and serum prohepcidin was significantly lower in diabetic patients than in control subjects. Serum total and high molecular weight (HMW) adiponectin correlated negatively with serum ferritin in control subjects or diabetic patients, while serum total and HMW adiponectin correlated positively with serum prohepcidin in diabetic patients, but not in control subjects. Serum total and HMW adiponectin were lower in patients with hyperferritinemia than in those without it. In conclusion, serum ferritin was increased in type 2 diabetic patients, while serum prohepcidin was decreased. A high serum ferritin was associated with insulin resistance, and with low serum total and HMW adiponectin in patients with type 2 diabetes.

Early apoptotic vascular signaling is determined by Sirt1 through nuclear shuttling, forkhead trafficking, bad, and mitochondrial caspase activation

Complications of diabetes mellitus (DM) weigh heavily upon the endothelium that ultimately affect multiple organ systems. These concerns call for innovative treatment strategies that employ molecular pathways responsible for cell survival and longevity. Here we show in a clinically relevant model of DM with elevated D-glucose that endothelial cell (EC) SIRT1 is vital for the prevention of early membrane apoptotic phosphatidylserine externalization and subsequent DNA degradation supported by studies with modulation of SIRT1 activity and gene knockdown of SIRT1. Furthermore, during elevated D-glucose exposure, we show that SIRT1 is sequestered in the cytoplasm of ECs, but specific activation of SIRT1 shuttles the protein to the nucleus to allow for cytoprotection. The ability of SIRT1 to avert apoptosis employs the activation of protein kinase B (Akt1), the post-translational phosphorylation of the forkhead member FoxO3a, the blocked trafficking of FoxO3a to the nucleus, and the inhibition of FoxO3a to initiate a "pro-apoptotic" program as shown by complimentary gene knockdown studies of FoxO3a. Vascular apoptotic oversight by SIRT1 extends to the direct modulation of mitochondrial membrane permeability, cytochrome c release, Bad activation, and caspase 1 and 3 activation, since inhibition of SIRT1 activity and gene knockdown of SIRT1 significantly accentuate cascade progression while SIRT1 activation abrogates these apoptotic elements. Our work identifies vascular SIRT1 and its control over early apoptotic membrane signaling, Akt1 activation, post-translational modification and trafficking of FoxO3a, mitochondrial permeability, Bad activation, and rapid caspase induction as new avenues for the treatment of vascular complications during DM.

Diabetes mellitus: channeling care through cellular discovery

Diabetes mellitus (DM) impacts a significant portion of the world's population and care for this disorder places an economic burden on the gross domestic product for any particular country. Furthermore, both Type 1 and Type 2 DM are becoming increasingly prevalent and there is increased incidence of impaired glucose tolerance in the young. The complications of DM are protean and can involve multiple systems throughout the body that are susceptible to the detrimental effects of oxidative stress and apoptotic cell injury. For these reasons, innovative strategies are necessary for the implementation of new treatments for DM that are generated through the further understanding of cellular pathways that govern the pathological consequences of DM. In particular, both the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)), nicotinamide, and the growth factor erythropoietin offer novel platforms for drug discovery that involve cellular metabolic homeostasis and inflammatory cell control. Interestingly, these agents and their tightly associated pathways that consist of cell cycle regulation, protein kinase B, forkhead transcription factors, and Wnt signaling also function in a broader sense as biomarkers for disease onset and progression.

FOXO3a governs early and late apoptotic endothelial programs during elevated glucose through mitochondrial and caspase signaling

Mechanisms that preserve endothelial cell (EC) integrity remain elusive, but are critical for new strategies directed against endocrine disorders such as diabetes mellitus (DM). Here we demonstrate in primary cerebral ECs with a clinically relevant model of elevated d-glucose that Akt1 and the post-translational modification and subcellular trafficking of the forkhead transcription factor FoxO3a are critical for early apoptotic membrane signaling and subsequent degradation of nuclear DNA. FoxO3a also directly governs apoptotic mitochondrial signal transduction pathways, since gene knockdown of FoxO3a prevents mitochondrial membrane depolarization as well as the release of cytochrome c. Control of this apoptotic cascade extends to the rapid and progressive activation of caspases. The presence of FoxO3a is necessary for cleaved (active) caspase 1 and 3 expression, since loss of FoxO3a abrogates the induction of caspase activity. Our work identifies Akt1, FoxO3a and closely aligned pathways as key therapeutic targets during impaired glucose tolerance and DM.