Pablo E. Pergola

Cutaneous Active Vasodilation in Humans Is Mediated by Cholinergic Nerve Cotransmission

During heat stress, increases in blood flow in nonglabrous skin in humans are mediated through active vasodilation by an unknown neurotransmitter mechanism. To investigate this mechanism, a three-part study was performed to determine the following: (1) Is muscarinic receptor activation necessary for active cutaneous vasodilation? We iontophoretically applied atropine to a small area of forearm skin. At that site and an untreated control site, we measured the vasomotor (laser-Doppler blood flow [LDF]) and sudomotor (relative humidity) responses to whole-body heat stress. Blood pressure was monitored. Cutaneous vascular conductance (CVC) was calculated (LDF divided by mean arterial pressure). Sweating was blocked at treated sites only. CVC rose at both sites (P < .05 at each site); thus, cutaneous active vasodilation is not effected through muscarinic receptors. (2) Are nonmuscarinic cholinergic receptors present on cutaneous arterioles? Acetylcholine (ACh) was iontophoretically applied to forearm skin at sites pretreated by atropine iontophoresis and at untreated sites. ACh increased CVC at untreated sites (P < .05) but not at atropinized sites. Thus, the only functional cholinergic receptors on cutaneous vessels are muscarinic. (3) Does cutaneous active vasodilation involve cholinergic nerve cotransmission? Botulinum toxin was injected intradermally in the forearm to block release of ACh and any coreleased neurotransmitters. Heat stress was performed as in part 1 of the study. At treated sites, CVC and relative humidity remained at baseline levels during heat stress (P > .05). Active vasodilator and sudomotor responses to heat stress were abolished by botulinum toxin. We conclude that cholinergic nerve activation mediates cutaneous active vasodilation through release of an unknown cotransmitter, not through ACh.

Targeting the transcription factor Nrf2 to ameliorate oxidative stress and inflammation in chronic kidney disease

Oxidative stress and inflammation are mediators in the development and progression of chronic kidney disease (CKD) and its complications, and they are inseparably linked as each begets and amplifies the other. CKD-associated oxidative stress is due to increased production of reactive oxygen species (ROS) and diminished antioxidant capacity. The latter is largely caused by impaired activation of Nrf2, the transcription factor that regulates genes encoding antioxidant and detoxifying molecules. Protective effects of Nrf2 are evidenced by amelioration of oxidative stress, inflammation, and kidney disease in response to natural Nrf2 activators in animal models, while Nrf2 deletion amplifies these pathogenic pathways and leads to autoimmune nephritis. Given the role of impaired Nrf2 activity in CKD-induced oxidative stress and inflammation, interventions aimed at restoring Nrf2 may be effective in retarding CKD progression. Clinical trials of the potent Nrf2 activator bardoxolone methyl showed significant improvement in renal function in CKD patients with type 2 diabetes. Results of the ongoing BEACON trial investigating the effect of this drug on time to end-stage renal disease or cardiovascular death will help further characterize the efficacy of Nrf2 pharmacological modulation in CKD. This article provides an overview of the role of impaired Nrf2 activity in the pathogenesis of CKD-associated oxidative stress and inflammation and the potential utility of targeting Nrf2 in the treatment of CKD.

Effect of Bardoxolone Methyl on Kidney Function in Patients with T2D and Stage 3b-4 CKD

Background/Aims: Bardoxolone methyl, a novel synthetic triterpenoid, induces Nrf2, a transcription factor known to play a key role in decreasing oxidative stress and the production of pro-inflammatory molecules. Methods: This exploratory multi-center, open-label study assessed the clinical activity and safety of bardoxolone methyl in 20 patients with moderate to severe chronic kidney disease and type 2 diabetes. Patients received 25 mg of bardoxolone methyl daily for 28 days, followed by 75 mg daily for another 28 days. Results: The study achieved its primary efficacy endpoint, as demonstrated by a significant increase from baseline in estimated glomerular filtration rate (eGFR) of 7.2 ml/min/1.73 m2 (p < 0.001). Improvements were seen in approximately 90% of patients and showed a dose- and time-dependent increase in eGFR. The eGFR change paralleled a significant reduction in serum creatinine (–0.3 mg/dl) and blood urea nitrogen (–4.9 mg/dl), along with an increase in creatinine clearance (+14.6 ml/min/1.73 m2), without a change in the 24-hour creatinine excretion rate. Markers of vascular injury and inflammation were improved by treatment with bardoxolone. No life-threatening adverse events or drug-related serious adverse events were reported. Conclusions: The results describe an apparent increase in kidney function following relatively short-term treatment with bardoxolone methyl, a promising new agent that warrants placebo-controlled studies to define its long-term effects on renal function.

The Secondary Prevention of Small Subcortical Strokes (SPS3) study.

Background Small subcortical strokes, also known as lacunar strokes, comprise more than 25% of brain infarcts, and the underlying vasculopathy is the most common cause of vascular cognitive impairment. How to optimally prevent stroke recurrence and cognitive decline in S3 patients is unclear. The aim of the Secondary Prevention of Small Subcortical Strokes study (Trial registration: NCT00059306) is to define strategies for reducing stroke recurrence, cognitive decline, and major vascular events. Methods Secondary Prevention of Small Subcortical Strokes is a randomised, multicentre clinical trial (n=3000) being conducted in seven countries, and sponsored by the US NINDS/NIH. Patients with symptomatic small subcortical strokes in the six-months before and an eligible lesion on magnetic resonance imaging are simultaneously randomised, in a 2 × 2 factorial design, to antiplatelet therapy – 325 mg aspirin daily plus 75 mg clopidogrel daily, vs. 325 mg aspirin daily plus placebo, double-blind – and to one of two levels of systolic blood pressure targets –‘intensive’ (<130 mmHg) vs. ‘usual’ (130–149 mmHg). Participants are followed for an average of four-years. Time to recurrent stroke (ischaemic or haemorrhagic) is the primary outcome and will be analysed separately for each intervention. The secondary outcomes are the rate of cognitive decline and major vascular events. The primary and most secondary outcomes are adjudicated centrally by those unaware of treatment assignment. Conclusions Secondary Prevention of Small Subcortical Strokes will address several important clinical and scientific questions by testing two interventions in patients with recent magnetic resonance imaging-defined lacunar infarcts, which are likely due to small vessel disease. The results will inform the management of millions of patients with this common vascular disorder.

Kidney transplantation during the first trimester of pregnancy : Immunosuppression with mycophenolate mofetil, tacrolimus, and prednisone

We present a case of living, related-donor kidney transplantation during the first trimester of pregnancy. The patient received mycophenolate mofetil (MMF), tacrolimus, and prednisone throughout the entire pregnancy. This is the first reported case of use of MMF during pregnancy. The mother did well, except for mild preeclampsia and mild renal insufficiency at term. The baby girl was born prematurely at week 353/7. The only possible teratogenic effects detected included hypoplastic nails and short fifth fingers. No chromosomal abnormalities were found. The child is growing and developing normally. Although we do not recommend the use of mycophenolate mofetil during pregnancy based on this experience, it is reassuring to know that a successful outcome can be expected in mothers treated with MMF during pregnancy.

A 12-Week, Double-Blind, Placebo-Controlled Trial of Ferric Citrate for the Treatment of Iron Deficiency Anemia and Reduction of Serum Phosphate in Patients With CKD Stages 3-5

BACKGROUND Iron deficiency anemia and serum phosphate levels > 4.0mg/dL are relatively common in chronic kidney disease stages 3 to 5 and are associated with higher risks of progressive loss of kidney function, cardiovascular events, and mortality. STUDY DESIGN Double-blind, placebo-controlled, randomized trial. SETTING & PARTICIPANTS 149 patients with estimated glomerular filtration rates < 60 mL/min/1.73 m(2), iron deficiency anemia (hemoglobin, 9.0-12.0 g/dL; transferrin saturation [TSAT]≤ 30%, serum ferritin ≤ 300 ng/mL), and serum phosphate levels ≥ 4.0 to 6.0mg/dL. Use of intravenous iron or erythropoiesis-stimulating agents was prohibited. INTERVENTION Randomization to treatment for 12 weeks with ferric citrate coordination complex (ferric citrate) or placebo. OUTCOMES & MEASUREMENTS Coprimary end points were change in TSAT and serum phosphate level from baseline to end of study. Secondary outcomes included change from baseline to end of treatment in values for ferritin, hemoglobin, intact fibroblast growth factor 23 (FGF-23), urinary phosphate excretion, and estimated glomerular filtration rate. RESULTS Ferric citrate treatment increased mean TSAT from 22% ± 7% (SD) to 32% ± 14% and reduced serum phosphate levels from 4.5 ± 0.6 to 3.9 ± 0.6 mg/dL, while placebo exerted no effect on TSAT (21% ± 8% to 20% ± 8%) and less effect on serum phosphate level (4.7 ± 0.6 to 4.4 ± 0.8 mg/dL; between-group P<0.001 for each). Ferric citrate increased hemoglobin levels (from 10.5 ± 0.8 to 11.0 ± 1.0 g/dL; P<0.001 vs placebo), reduced urinary phosphate excretion 39% (P<0.001 vs placebo), and reduced serum intact FGF-23 levels from a median of 159 (IQR, 102-289) to 105 (IQR, 65-187) pg/mL (P=0.02 vs placebo). The incidence and severity of adverse effects were similar between treatment arms. LIMITATIONS The study is limited by relatively small sample size and short duration and by having biochemical rather than clinical outcomes. CONCLUSIONS Short-term use of ferric citrate repletes iron stores, increases hemoglobin levels, and reduces levels of serum phosphate, urinary phosphate excretion, and FGF-23 in patients with chronic kidney disease stages 3 to 5.

Reactive Carbonyls and Polyunsaturated Fatty Acids Produce a Hydroxyl Radical-like Species A POTENTIAL PATHWAY FOR OXIDATIVE DAMAGE OF RETINAL PROTEINS IN DIABETES

The pattern of oxidized amino acids in aortic proteins of nonhuman primates suggests that a species resembling hydroxyl radical damages proteins when blood glucose levels are high. However, recent studies argue strongly against a generalized increase in diabetic oxidative stress, which might instead be confined to the vascular wall. Here, we describe a pathway for glucose-stimulated protein oxidation and provide evidence of its complicity in diabetic microvascular disease. Low density lipoprotein incubated with pathophysiological concentrations of glucose became selectively enriched in ortho-tyrosine and meta-tyrosine, implicating a hydroxyl radical-like species in protein damage. Model system studies demonstrated that the reaction pathway requires both a reactive carbonyl group and a polyunsaturated fatty acid, involves lipid peroxidation, and is blocked by the carbonyl scavenger aminoguanidine. To explore the physiological relevance of the pathway, we used mass spectrometry and high pressure liquid chromatography to quantify oxidation products in control and hyperglycemic rats. Hyperglycemia raised levels of ortho-tyrosine, meta-tyrosine, and oxygenated lipids in the retina, a tissue rich in polyunsaturated fatty acids. Rats that received aminoguanidine did not show this increase in protein and lipid oxidation. In contrast, rats with diet-induced hyperlipidemia in the absence of hyperglycemia failed to exhibit increased protein and lipid oxidation products in the retina. Our observations suggest that generation of a hydroxyl radical-like species by a carbonyl/polyunsaturated fatty acid pathway might promote localized oxidative stress in tissues vulnerable to diabetic damage. This raises the possibility that antioxidant therapies that specifically inhibit the pathway might delay the vascular complications of diabetes.

Rationale and Trial Design of Bardoxolone Methyl Evaluation in Patients with Chronic Kidney Disease and Type 2 Diabetes : The Occurrence of Renal Events (BEACON)

Background: Chronic kidney disease (CKD) associated with type 2 diabetes mellitus constitutes a global epidemic complicated by considerable renal and cardiovascular morbidity and mortality, despite the provision of inhibitors of the renin-angiotensin-aldosterone system (RAAS). Bardoxolone methyl, a synthetic triterpenoid that reduces oxidative stress and inflammation through Nrf2 activation and inhibition of NF-κB was previously shown to increase estimated glomerular filtration rate (eGFR) in patients with CKD associated with type 2 diabetes mellitus. To date, no antioxidant or anti-inflammatory therapy has proved successful at slowing the progression of CKD. Methods: Herein, we describe the design of Bardoxolone Methyl Evaluation in Patients with Chronic Kidney Disease and Type 2 Diabetes: the Occurrence of Renal Events (BEACON) trial, a multinational, multicenter, double-blind, randomized, placebo-controlled Phase 3 trial designed to determine whether long-term administration of bardoxolone methyl (on a background of standard therapy, including RAAS inhibitors) safely reduces renal and cardiac morbidity and mortality. Results: The primary composite endpoint is time-to-first occurrence of either end-stage renal disease or cardiovascular death. Secondary endpoints include the change in eGFR and time to occurrence of cardiovascular events. Conclusion: BEACON will be the first event-driven trial to evaluate the effect of an oral antioxidant and anti-inflammatory drug in advanced CKD.

Metabolic factors in the development of hepatic steatosis and altered mitochondrial gene expression in vivo

The objective of the study was to understand the role in vivo of elevated plasma free fatty acids (FFA), insulin, and glucose levels in the development of steatosis and altered mitochondrial gene/protein expression. We studied 4 groups of Sprague-Dawley rats: (1) high-fat diet (HFD), (2) high-dose streptozotocin-induced diabetes (T1DM), (3) low-dose streptozotocin-induced diabetic rats on an HFD (T2DM), and (4) controls. Liver histology and expression of genes/proteins related to mitochondrial fatty acid oxidation and biogenesis were analyzed. Despite an attempt to compensate by increasing expression of genes of fatty acid oxidation (carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase), the HFD and diabetic groups developed marked steatosis and suffered a significant reduction in mitochondrial biogenesis gene expression (nuclear respiratory factor 1/transcriptional factor A, mitochondrial). In T2DM rats, the combination of high glucose and FFA unexpectedly did not lead to greater fat accumulation than HFD alone. Greater steatosis in HFD vs T2DM (P < .001) correlated with impairment in the gene expression of PPAR-α (ie, fatty acid oxidation) and PGC1α, a major coactivator for mitochondrial biogenesis. Steatosis was not severe in insulin-deficient T1DM rats despite very elevated FFA and glucose levels. Increased carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase/PPAR-α gene expression suggested inadequate adaptation to high FFA in both T1DM/T2DM rats. Hyperinsulinemia combined with elevated FFA is the key metabolic factor driving hepatic lipogenesis in vivo (HFD rats). Mitochondrial biogenesis (nuclear respiratory factor 1; transcriptional factor A, mitochondrial) is highly susceptible to FFA-induced steatosis. In contrast, hyperglycemia does not have an additive effect (T2DM) and leads to only a modest degree of steatosis in the absence of hyperinsulinemia, even when FFA are extremely elevated as in T1DM rats.

Race and Sex Differences in Hypertension Control in CKD : Results From the Kidney Early Evaluation Program (KEEP)

BACKGROUND African American men with chronic kidney disease (CKD) progress to end-stage renal disease more rapidly than African American women or whites. Uncontrolled hypertension worsens CKD, and disparities in hypertension control may contribute to disparities in CKD progression. STUDY DESIGN Cross-sectional. SETTING & PARTICIPANTS 10,827 individuals with CKD and self-reported hypertension screened in the Kidney Early Evaluation Program. PREDICTORS African American race, sex. OUTCOMES Hypertension control (blood pressure <130 mm Hg systolic and/or <80 mm Hg diastolic). MEASUREMENTS Self-report, physical examination (blood pressure), laboratory data (serum creatinine, microalbuminuria by urine dipstick). We calculated estimated glomerular filtration rates by using the 4-variable isotope dilution mass spectrometry Modification of Diet in Renal Disease Study equation. We classified CKD as early (stages 1 to 2) or late (stages 3 to 5) based on estimated glomerular filtration rate and microalbuminuria. RESULTS In individuals with early CKD, African American women (odds ratio [OR], 1.47; 95% confidence interval [CI], 1.14 to 1.88), white men (OR, 1.85; 95% CI, 1.39 to 2.46), and white women (OR, 1.69; 95% CI, 1.28 to 2.22) had greater odds of hypertension control (blood pressure <130/80 mm Hg) than African American men. In individuals with late CKD, white men (OR, 1.66; 95% CI, 1.10 to 2.52) and white women (OR, 1.67; 95% CI, 1.13 to 2.46) had greater odds of hypertension control than African American men. No differences were seen between African American men and women with late CKD. LIMITATIONS No information for medication regimens. CONCLUSIONS African American men with CKD have poorly controlled hypertension compared with African American women and whites, particularly in the early stages of disease. Efforts to aggressively treat hypertension in this population may help narrow the race and sex disparities in progression to end-stage renal disease.