Andrew H. Frankel

Urinary monocyte chemoattractant protein-1 (MCP-1) and connective tissue growth factor (CCN2) as prognostic markers for progression of diabetic nephropathy

Profibrotic growth factors and inflammatory chemokines have been implicated in the pathogenesis of diabetic nephropathy (DN). However, measurement of urinary monocyte chemoattractant protein-1 (MCP-1) and connective tissue growth factor (CCN2) as prognostic markers has not previously been reported, and neither have two such molecules in urine been examined in a single study of DN. In this prospective observational study, 43 adult diabetic patients were studied, 40 were followed up for 6years. Urinary MCP-1/creatinine ratios were found to be significantly higher in patients with macroalbuminuria (3.3- and 2.1-fold higher (p<0.01) than normoalbuminuric and microalbuminuric patients, respectively). CCN2 exhibited a pattern different from that of urinary MCP-1. Urinary CCN2/creatinine ratios were greatly elevated in both microalbuminuric and macroalbuminuric patients (125- and 74-fold higher than normoalbuminuric patients, respectively, p<0.01 and p<0.05, respectively). Further, urinary CCN2, but not MCP-1, correlated with progression of microalbuminuria (R=0.49, p<0.05). In contrast, MCP-1, but not CCN2, correlated with the rate of eGFR decline for all patients (R=0.61, p<0.0001), reflective of its predictive value in patients with macroalbuminuria, but not for patients with microalbuminuria or normoalbuminuria. In conclusion, increased urinary CCN2 is associated with the early progression of DN, whereas MCP-1 is associated with later stage disease.

Oral cholecalciferol decreases albuminuria and urinary TGF-β1 in patients with type 2 diabetic nephropathy on established renin-angiotensin-aldosterone system inhibition.

The anti-inflammatory, antifibrotic, and antiproteinuric properties of vitamin D have been defined in studies using active vitamin D analogs. In this prospective observational study we determined whether nutritional vitamin D repletion can have additional beneficial effects in patients with type 2 diabetic nephropathy already established on renin-angiotensin-aldosterone system inhibition. During a 7-month period, 63 patients were enrolled and those with low levels of 25(OH)D were treated with oral cholecalciferol for 4 months. Baseline serum 25(OH)D and 1,25(OH)(2)D showed no significant correlation with baseline urinary MCP-1, TGF-β1, or albuminuria measured as the urinary albumin-to-creatinine ratio. Of the 63 patients, 54 had insufficient or deficient levels of serum 25(OH)D and 49 complied with cholecalciferol therapy and follow-up. Both 25(OH)D and 1,25(OH)(2)D were significantly increased at 2 and 4 months of treatment. Albuminuria and urinary TGF-β1 decreased significantly at both time points compared to their baseline values, while urinary MCP-1 did not change. Thus, in the short term, dietary vitamin D repletion with cholecalciferol had a beneficial effect in delaying the progression of diabetic nephropathy above that due to established renin-angiotensin-aldosterone system inhibition.

Effect of bariatric surgery-induced weight loss on renal and systemic inflammation and blood pressure: a 12-month prospective study.

BACKGROUND Bariatric surgery improves arterial hypertension and renal function; however, the underlying mechanisms and effect of different surgical procedures are unknown. In the present prospective study, we compared the 12-month follow-up results after Roux-en-Y gastric bypass, laparoscopic adjustable gastric banding, and laparoscopic sleeve gastrectomy on weight loss, hypertension, renal function, and inflammatory status. METHODS A total of 34 morbidly obese patients were investigated before, one and 12 months after Roux-en-Y gastric bypass (n = 10), laparoscopic adjustable gastric banding (n = 13), and laparoscopic sleeve gastrectomy (n = 11) for hypertension, kidney function, urinary and serum cytokine levels of macrophage migration inhibitory factor, monocyte chemotactic protein-1, and chemokine ligand-18. RESULTS At 12 months after surgery, the patients in all 3 treatment arms showed a significant decrease in the mean body mass index, mean arterial pressure, and urinary and serum inflammatory markers (all P < .001). The reduction in urinary and serum cytokine levels correlated directly with body weight loss (P < .05). Patients with impaired renal function at baseline (corresponding to serum cystatin C >.8 mg/L) had a marked improvement in renal function 12 months after surgery (P < .05). CONCLUSION Surgically induced weight loss is associated with a marked decrease in renal and systemic inflammation and arterial hypertension and improvement in renal function in patients with pre-existing renal impairment. These effects appear to be independent of surgical procedure. The improvement in renal inflammation could be 1 of the mechanisms contributing to the beneficial effects of bariatric surgery on arterial blood pressure, proteinuria, and renal function.

Assessing glycemic control in maintenance hemodialysis patients with type 2 diabetes.

OBJECTIVE Optimizing glycemic control in diabetic patients undergoing maintenance hemodialysis requires accurate assessment. We hypothesize that 1) 48-h continuous glucose monitoring (CGM) provides additional, clinically relevant, information to that provided by the A1C measurement and 2) glycemic profiles differ significantly between day on and day off dialysis. RESEARCH DESIGN AND METHODS With the use of GlucoDay S, 48-h CGM was performed in 19 type 2 diabetic subjects undergoing hemodialysis to capture consecutive 24-h periods on and off dialysis. Energy intake was calculated using food diaries. A1C was assayed by a high-performance liquid chromatography method. RESULTS CGM data were available for 17 subjects (13 male) with a mean (range) age of 61.5 years (42–79 years) and diabetes duration of 18.8 years (4–30 years). The 24-h CGM area under the glucose curve and 24-h mean glucose values were significantly higher during the day off dialysis than on dialysis (5,932.1 ± 2,673.6 vs. 4,694 ± 1,988.0 mmol · 3 min−1 · l−1, P = 0.022, and 12.6 ± 5.6 vs. 9.8 ± 3.8 mmol/l, P = 0.013, respectively), independent of energy intake. Asymptomatic hypoglycemia occurred in 4 subjects, 3 within 24 h of dialysis, and the glucose nadir in 14 subjects occurred within 24 h of dialysis. CONCLUSIONS Glucose values are significantly lower on dialysis days than on nondialysis days despite similar energy intake. The risk of asymptomatic hypoglycemia was highest within 24 h of dialysis. Physicians caring for patients undergoing hemodialysis need to be aware of this phenomenon and consider enhanced glycemic monitoring after a hemodialysis session. CGM provides glycemic information in addition to A1C, which is potentially relevant to clinical management.

Renal cytokines improve early after bariatric surgery

Bariatric surgery has been suggested to improve arterial hypertension and renal function. This prospective controlled observational study aimed to investigate changes in renal inflammation, renal function and arterial blood pressure before and after bariatric surgery.

The effect of bariatric surgery on renal function and disease: a focus on outcomes and inflammation

Renal dysfunction and disease, including hyperfiltration, proteinuria and hypofiltration, are commonly associated with obesity. Diabetic kidney disease is also common in obese cohorts. Weight loss interventions, including bariatric surgery, can effectively reduce weight and improve renal outcomes. Some of this effect may be due to the remission of Type 2 diabetes and hypertension. However, other mechanisms, including the resolution of inflammatory processes, may also contribute. The effect of bariatric surgery on renal function has only recently become a focus of particular investigation. In this study, we will review the effects of bariatric surgery on obesity-associated kidney disease. We will discuss the pitfalls in assessing renal function in obese cohorts and will examine the effect of bariatric surgery on renal function and urinary protein excretion using different mechanisms. We will give particular attention to the evidence for bariatric surgery in cohorts with established renal disease and suggest future directions. In particular, we will outline the evidence for inflammation as an important therapeutic target, and the emerging medical therapies being considered to exploit this target in obesity- and diabetes-related kidney disease.

Sodium and water handling after gastric bypass surgery in a rat model

BACKGROUND It was the aim to investigate the influence of gastric bypass on renal sodium and water handling. The relationship between sodium and water absorption along the gastrointestinal tract and their renal excretion is poorly understood. Beneficial effects on blood pressure have been seen after bariatric surgery before significant weight loss has occurred. METHODS Male Wistar rats (348 ± 19 g) underwent either gastric bypass (n = 14) or sham operation (n = 7) and were given a low-sodium diet with deionized water ad libitum. Before and after surgery, the rats received an oral sodium load (1.5 mmol/kg) as hyperosmolar saline (616 mM), and were then placed in individual metabolic cages so the urine volume, sodium content, and water intake for 8 hours could be recorded. The urine sodium concentration was also measured. RESULTS The rats that had undergone gastric bypass had a significantly lower body weight than the sham-operated controls throughout the follow-up period (346 ± 21 g versus 501.3 ± 8.0 g at day 60; P = .0004). An oral sodium load after gastric bypass led to an increase in water intake (.07 ± .01 mL/g versus .03 ± .01 mL/g; P = .023), urine output (.03 ± .01 mL/g versus .02 ± .002 mL/g; P = .027), and sodium excretion (65.99 ± 10.7 mol versus 31.71 ± 8.7 mol; P = .020). No change was seen in water intake, urine output, or sodium excretion after sham surgery. CONCLUSION Urine output, water intake, and sodium excretion are all increased after gastric bypass surgery in rats given an oral sodium load compared with sham-operated controls. More rapid excretion, and less retention, of a dietary sodium load could be a part of the mechanism underlying the beneficial effect of bariatric surgery on blood pressure.

Early detection of subclinical left ventricular myocardial dysfunction in patients with chronic kidney disease

AIMS To identify subclinical left ventricular (LV) myocardial dysfunction using speckle tracking echocardiography (STE) in patients with chronic kidney disease (CKD), preserved LV ejection fraction (LVEF), and no cardiovascular history or symptoms. METHODS AND RESULTS Cross-sectional comparisons of conventional and STE parameters were performed between controls and patients with different stages of CKD. CKD patients were followed up for major adverse cardiovascular events (MACEs). We recruited 106 CKD patients and 38 controls. Mean age was 54.4 ± 15.1 and 36.9 ± 11.5 years, respectively (P < 0.001), with 49.1 vs. 52.6% being female (P = 0.705). There were 29 (27.4%) patients with CKD stages 1/2, 38 (35.8%) with stage 3, and 39 (36.8%) with stages 4/5. Global longitudinal strain (GLS) was more impaired when moving from controls to CKD stages 4/5 (-20.67 ± 3.06, -20.39 ± 2.29, -18.33 ± 3.81, -18.01 ± 2.64, controls vs. CKD stages 1/2, vs. CKD stage 3, vs. CKD stages 4/5, respectively, Padjusted = 0.016), whereas LV twist (16.2 ± 4.8, 18.51 ± 4.36, 19.91 ± 5.35, 24.6 ± 5.35, Padjusted < 0.001) and LV twist rate (101.7 ± 30.3, 110.4 ± 30.1, 121 ± 31.4, 154.8 ± 36.7, Padjusted < 0.001) increased. Risk factor-adjusted GLS (standardized beta β = -0.245, P = 0.025), strain rate (SR) [global longitudinal strain rates (GLSRs); β = -0.236, P = 0.019], and early diastolic longitudinal strain rate (GLSRe; β = 0.247, P = 0.019) were significantly associated with estimated glomerular filtration rate (eGFR), whereas LV twist (β = -0.432, P < 0.001), LV twist rate (β = -0.433, P < 0.001), and number of segments with diastolic dysfunction (β = -340, P < 0.001) were inversely and independently associated with eGFR. Impaired GLS (more than -16%) was observed in almost a quarter of CKD patients and associated with a reduced estimated MACE-free survival at 12-month follow-up (88.5 vs 93.7%, Plogrank = 0.038). CONCLUSION In CKD patients with no cardiovascular symptoms or history and preserved LVEF, STE can identify subclinical abnormalities of both systolic (decreased GLS and GLSR, increased LV twist, and twist rate) and diastolic (decreased GLSRe and increased number of segments with diastolic dysfunction) LV function.

Urine Proteomics and Biomarkers in Renal Disease

The application of urine proteomics is a useful approach to the study of the proteins involved in healthy and diseased kidneys and may provide a noninvasive approach to assess disease activity and to monitor clinical response in patients with renal diseases. This technique may provide an additional tool in clinical trials and for the assessment of prognosis for patients. Both soluble proteins and membrane-bound (exosomal) proteins may be studied, and multiple approaches are available. Discovery proteomics is an unbiased approach to detect novel proteins in urine samples. Mass spectrometry (MS) is often needed to identify specific protein fragments. Targeted proteomics often involves specific immunoassays or modified MS, which enables a hypothesis-based design. These approaches may be integrated. For example, specific proteins may be identified by the discovery approach or laboratory study of disease mechanisms. These proteins will then be studied further by targeted proteomics. In order to translate to clinical practice, the specific assays need vigorous validation by means of sufficiently statistically powered clinical trials.

Improved blood pressure, nitric oxide and asymmetric dimethylarginine are independent after bariatric surgery

Background Obesity is associated with hypertension, but the exact mechanism is not fully understood. Bariatric surgery significantly decreases weight and blood pressure (BP). Low plasma nitric oxide (NO) and raised asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO, concentrations are associated with both obesity and hypertension. Correlations between the changes in these parameters were studied after bariatric surgery. Methods Weight, BP, plasma ADMA and NO were measured in 29 obese patients (24 female, 5 male) before and six weeks after bariatric surgery. Results Patients were 39.2 ± 1.2 (mean ± SEM) years old and weighed 126 ± 3 kg. Six weeks after the surgery, patients had lost 10 ± 0.7 kg (P < 0.0001) and mean arterial pressure (MAP) decreased by 11 ± 1.0 mmHg (P < 0.0001). The plasma ADMA concentration decreased by 24 ± 2% from 5 ± 0.4 to 4.0 ± 0.3 μmol/L (P < 0.0001). The plasma total nitrite concentration increased by 15 ± 1% from 51.4 ± 2.6 to 60 ± 3 μmol/L (P < 0.0001). The correlation between the decrease of ADMA and increase of NO subsequent to weight loss was significant (P < 0.0001). However, MAP was not correlated to the changes in ADMA or NO. Conclusions After bariatric surgery, beneficial changes in BP, NO and ADMA occur, but our findings suggest that these BP changes are independent of changes in the NO–ADMA axis. Other causes for the changes in BP should therefore be considered.