Comanagement of diabetic kidney disease by the primary care provider and nephrologist.

DKD is a complex and multifaceted disease. A substantial portion of patients remain unable to attain clinical targets for glycosylated hemoglobin, lipids, and blood pressure. Improving outcomes requires multifactorial interventions that are best delivered through collaborative care. Targets for improvement should include screening, diagnosis, and early referral. Following referral, the patient should be cared for in an integrated framework using the 4 elements of an effective DKD care delivery model: clear roles and responsibilities, integrated QI programs, MDT approach, and effective communication facilitated through access to a shared EMR. Given the differences in the pathophysiology of DM in the renal population, a nephrologist and endocrinologist can be invaluable in improving care for this population. Large-scale trials are needed to validate the cost and usefulness of collaborative care as current data are insufficient. Based on available data, models such as the one proposed here should serve to maximize the strengths of individual providers and provide improved quality of care to patients.

Activated CD4+ T cells target mesangial antigens and initiate glomerulonephritis.

AIMS: The role of kidney infiltrating T cells in the pathology of lupus nephritis is unclear. This study was undertaken to investigate whether CD4+ T cell responses to a surrogate mesangial antigen can initiate glomerulonephritis. METHODS: Ovalbumin (OVA) was deposited in the glomerular mesangium of C57BL/6 (B6) mice using anti-α8-integrin immunoliposomes (α8ILs). This was followed by injection of activated OVA-reactive CD4+ transgenic OT2 T cells. Trafficking of antigen-specific OT2 T cells to kidneys and lymph nodes was studied by flow cytometry. Glomerular pathology and immune cell infiltration was characterized by immunostaining. Role of CCR2 deficiency on T cell-mediated glomerulonephritis was investigated using B6.ccr2(-/-) mice. RESULTS: α8ILs delivered OVA specifically to the renal glomeruli. Adoptively transferred OT2 T cells preferentially accumulated in renal lymph nodes and in the renal cortex. Kidneys showed glomerular inflammation with recruitment of endogenous T cells, dendritic cells and macrophages. T cell-mediated inflammation induced mesangial cell activation and an increase in glomerular MCP1 and fibronectin. The formation of inflammatory foci was driven by Ly6C monocytes and was CCR2 dependent. CONCLUSIONS: The findings from this study show that T cells reactive with antigens in the mesangium are sufficient to initiate glomerular pathology. Antigen-specific CD4 T cells act by inducing glomerular MCP1 production which mediates recruitment of inflammatory monocytes resulting in glomerulonephritis. Thus, down-modulation of T cell responses within the kidneys of lupus patients will be a beneficial therapeutic approach.

Factors affecting response and tolerability to ferumoxytol in nondialysis chronic kidney disease patients.

BACKGROUND: Ferumoxytol is a unique intravenous (i.v.) iron therapy. This report examines factors affecting hemoglobin response to i.v. ferumoxytol, and the relationship between hematologic parameters, concomitant erythropoiesis-stimulating agents (ESA), and adverse events (AEs) in nondialysis CKD patients. METHODS: A series of post-hoc efficacy and safety analyses were performed using pooled data from two identically designed Phase III studies in 608 nondialysis CKD patients randomized to receive two 510 mg i.v. injections of ferumoxytol within 5 ± 3 days versus oral iron. RESULTS: Ferumoxytol resulted in a significant increase in hemoglobin in the presence and absence of ESA, and across a range of baseline hemoglobin, transferrin saturation, ferritin, and reticulocyte hemoglobin content levels. Adverse event rates with ferumoxytol were similar across quartiles of change in hemoglobin; there were no trends suggesting an increased rate of cardiovascular AEs with higher maximum achieved hemoglobin or faster rate of hemoglobin rise. There was no meaningful difference in the rate of AEs, serious AEs, and cardiovascular AEs between patients receiving or not receiving ESA. CONCLUSIONS: These analyses add to the knowledge of predictors of response and safety outcomes associated with i.v. iron therapy in nondialysis CKD patients.

Monocyte/macrophage chemokine receptor CCR2 mediates diabetic renal injury.

Monocyte/macrophage recruitment correlates strongly with the progression of renal impairment in diabetic nephropathy (DN). C-C chemokine receptor (CCR)2 regulates monocyte/macrophage migration into injured tissues. However, the direct role of CCR2-mediated monocyte/macrophage recruitment in diabetic kidney disease remains unclear. We report that pharmacological blockade or genetic deficiency of CCR2 confers kidney protection in Ins2(Akita) and streptozotocin (STZ)-induced diabetic kidney disease. Blocking CCR2 using the selective CCR2 antagonist RS504393 for 12 wk in Ins2(Akita) mice significantly attenuated albuminuria, the increase in blood urea nitrogen and plasma creatinine, histological changes, and glomerular macrophage recruitment compared with vehicle. Furthermore, mice lacking CCR2 (CCR2(-/-)) mimicked CCR2 blockade by reducing albuminuria and displaying less fibronectin mRNA expression and inflammatory cytokine production compared with CCR2(+/+) mice, despite comparable blood glucose levels. Bone marrow-derived monocytes from CCR2(+/+) or CCR2(-/-) mice adoptively transferred into CCR2(-/-) mice reversed the renal tissue-protective effect in diabetic CCR2(-/-) mice as evaluated by increased urinary albumin excretion and kidney macrophage recruitment, indicating that CCR2 is not required for monocyte migration from the circulation into diabetic kidneys. These findings provide evidence that CCR2 is necessary for monocyte/macrophage-induced diabetic renal injury and suggest that blocking CCR2 could be a novel therapeutic approach in the treatment of DN.

Vascular access for HD: aligning payment with quality.

The Fistula First Breakthrough Initiative (FFBI) has improved the awareness of the value of fistula creation in patients with end-stage renal disease (ESRD). The FFBI Health Policy Workgroup has been charged with reviewing the relationship of policy and economic issues to this project. This article reviews the efforts and successes of renal community clinical activities and reemphasizes the economic impact of fistula creation and catheter reduction on the health care system. Major obstacles are discussed, and existing tools and efforts designed to address them are outlined. The FFBI Health Policy Workgroup then identifies less frequently recognized barriers to the achievement of the FFBI goals and suggests solutions to them. It concludes that nephrologists need to assume the leadership role and drive fistula creation and central venous catheter reduction to achieve programmatic success.

Chronic sphingosine 1-phosphate 1 receptor activation attenuates early-stage diabetic nephropathy independent of lymphocytes.

Sphingosine 1-phosphate (S1P), a pleiotropic lipid mediator, binds to five related G-protein-coupled receptors to exert its effects. As S1P1 receptor (S1P1R) activation blocks kidney inflammation in acute renal injury, we tested whether activation of S1P1Rs ameliorates renal injury in early-stage diabetic nephropathy (DN) in rats. Urinary albumin excretion increased in vehicle-treated diabetic rats (single injection of streptozotocin), compared with controls, and was associated with tubule injury and increased urinary tumor necrosis factor-α (TNF-α) at 9 weeks. These effects were significantly reduced by FTY720, a non-selective, or SEW2871, a selective S1P1R agonist. Interestingly, only FTY720 was associated with reduced total lymphocyte levels. Albuminuria was reduced by SEW2871 in both Rag-1 (T- and B-cell deficient) and wild-type diabetic mice after 6 weeks, suggesting that the effect was independent of lymphocytes. Another receptor, S1P3R, did not contribute to the FTY720-mediated protection, as albuminuria was also reduced in diabetic S1P3R knockout mice. Further, both agonists restored WT-1 staining along with podocin and nephrin mRNA expression, suggesting podocyte protection. This was corroborated in vitro, as SEW2871 reduced TNF-α and vascular endothelial growth factor mRNA expression in immortalized podocytes grown in media containing high glucose. Whether targeting kidney S1P1Rs will be a useful therapeutic measure in DN will need direct testing.

Pulmonary renal syndrome and emergency therapy.

The pulmonary renal syndrome is a symptom complex with simultaneous involvement of the kidneys and lungs. While this can be related to any concomitant kidney and lung dysfunction, the usual connotation is that of kidney dysfunction associated with pulmonary hemorrhage frequently manifesting as hemoptysis. Many causes of the pulmonary renal syndrome have been defined, and therapy is directed at the underlying etiologic factor for the syndrome. At times the presentation is life-threatening. In those situations emergency therapy must be initiated as soon as possible. A number of therapies are now available for this syndrome including pulse methylprednisolone and plasmapheresis. Emerging novel therapies show promise of augmenting the armamentarium of the clinician's therapeutic options. This review addresses the author's approach to the elaboration of the etiology of pulmonary renal syndrome and the therapeutic options available to the clinician.

Ferumoxytol for the treatment of anemia in chronic kidney disease.

Iron deficiency anemia is a common occurrence in patients with chronic kidney disease and many patients do not respond well to supplementation with oral iron. There are now five intravenous iron preparations available for use in the chronic kidney disease patient, with ferumoxytol being the most recently approved agent. As opposed to previously available intravenous irons, ferumoxytol has the advantage of not needing a test dose, allowing a large dose of iron (510 mg) to be given in a short period of time by bolus injection, and no reported cases of anaphylaxis. Ferumoxytol has advantages for use in the outpatient setting to treat iron deficiency, in patients with chronic kidney disease not yet on dialysis and in patients on peritoneal dialysis. The use of ferumoxytol in the hemodialysis population where thrice weekly intravenous access is the norm is less clear. Cost-effectiveness studies and post-approval studies on ferumoxytol as well as changes in the cost structure of dialysis reimbursement will likely have a large impact on the use of this new agent.

The mortality risk associated with higher hemoglobin: is the therapy to blame?

Recent trials have demonstrated a trend for increased mortality when patients with end-stage renal disease (ESRD) or chronic kidney disease (CKD) are treated with erythropoietin-stimulating agents (ESAs) to hemoglobin levels higher than recommended (>13 g/dl). Recent studies suggest that higher doses of ESAs, in themselves, may be at least partly responsible for this mortality risk. This is important, as more than 90% of patients with ESRD and approximately 20% of patients with CKD receive ESAs. Two new studies address this.

Effects of pyridoxamine in combined phase 2 studies of patients with type 1 and type 2 diabetes and overt nephropathy.

BACKGROUND/AIMS: Treatments of diabetic nephropathy (DN) delay the onset of end-stage renal disease. We report the results of safety/tolerability studies in patients with overt nephropathy and type 1/type 2 diabetes treated with pyridoxamine, a broad inhibitor of advanced glycation. METHODS: The two 24-week studies were multicenter Phase 2 trials in patients under standard-of-care. In PYR-206, patients were randomized 1:1 and had baseline serum creatinine (bSCr) or=2.0 but or=1.3 mg/dl, type 2 diabetes), a treatment effect was observed on the rise in serum creatinine (p = 0.007). No differences in urinary albumin excretion were seen. Urinary TGF-beta1 also tended to decrease with pyridoxamine (p = 0.049) as did the CML and CEL AGEs. CONCLUSION: These data provide a foundation for further evaluation of this AGE inhibitor in DN.

A nephritogenic peptide induces intermolecular epitope spreading on collagen IV in experimental autoimmune glomerulonephritis.

This group previously identified a peptide p13 of alpha3(IV)NC1 domain of type IV collagen that induces experimental autoimmune glomerulonephritis (EAG) in rats with generation of antibodies to sites on alpha3(IV)NC1 external to the peptide as a result of intramolecular epitope spreading. It was hypothesized that intermolecular epitope spreading to other collagen IV chains also was induced. Rats were immunized with nephritogenic peptide that was derived from the amino terminal part of rat alpha3(IV)NC1 domain, and serum and kidney eluate were examined for antibodies to both native and recombinant NC1 domains of collagen IV. Peptide induced EAG with proteinuria and decreased renal function and glomerular basement membrane IgG deposits. Sera from these rats were examined by ELISA, which revealed reactivity not only to immunizing peptide but also to human and rat alpha3(IV)NC1 and to human alpha4(IV)NC1 domains. Kidney eluate that was depleted of alpha3(IV)NC1 antibodies still reacted to alpha4(IV)NC1, and alpha3(IV)NC1 column-bound antibody reacted with alpha3(IV)NC1. There was minimal reactivity to other collagen chains. Eluate that was adsorbed to NC1 hexamer from rat glomerular basement membrane lost all reactivity to glomerular constituents, and the eluted antibodies reacted to alpha3(IV)NC1 and alpha4(IV)NC1 domains. These studies show that a T cell epitope of alpha3(IV)NC1 induces EAG, intramolecular epitope spreading along alpha3(IV)NC1, and intermolecular epitope spreading to alpha4(IV)NC1 domain with minimal or no reactivity to other collagen chains or glomerular constituents. This is the first demonstration in EAG of intermolecular epitope spreading and identification of the spread epitopes.

Adenosine A2A receptor activation attenuates inflammation and injury in diabetic nephropathy.

We previously demonstrated the anti-inflammatory effects and renal tissue protection in response to adenosine A(2A)-receptor (A(2A)R) activation in acute renal injury. We sought to extend these studies and determine the efficacy of A(2A)R agonists in a chronic model of renal injury. We hypothesized that A(2A) agonists mediate renal tissue protection in diabetic nephropathy by reducing glomerular inflammation. Diabetes was induced with single intravenous injection of streptozotocin in Sprague-Dawley rats (50 mg/kg). Increases in urinary albumin excretion (UAE) and plasma creatinine at week 6 in the diabetes group (26- and 6-fold over control, respectively) were markedly reduced by continuous subcutaneous administration of ATL146e (10 ng x kg(-1) x min(-1)), a selective A(2A) agonist. The increase in UAE in the diabetes group was associated with a significant reduction in the expression of slit diaphragm-associated molecules compared with control (nephrin; P < 0.05 and podocin; P < 0.005) that was reversed by ATL146e treatment. Diabetes led to an increase in urinary excretion of monocyte chemoattractant protein-1 (705% of control), TNF-alpha (1,586% of control), IFN-gamma (298% of control), kidney fibronectin mRNA (457% of control), and glomerular infiltration of macrophages (764% of control), effects significantly reduced by ATL146e treatment. Mesangial expansion and basement membrane thickness were reduced with ATL146e. To further confirm the selectivity of ATL146e, we used wild-type (WT) or A(2A)knockout (A(2A)-KO) mice. Four weeks after diabetes, UAE increased significantly in both WT and A(2A)-KO diabetic mice (3.0- and 3.3-fold over control). A(2A) agonist treatment blocked the increase in UAE in WT diabetic mice (P < 0.001), whereas it had no effect on the A(2A)-KO diabetic mice. These results demonstrate that chronic A(2A)R activation in diabetic rats 1) ameliorates histological and functional changes in kidneys induced by diabetes and 2) causes reduced inflammation associated with diabetic nephropathy.

The safety and efficacy of ferumoxytol therapy in anemic chronic kidney disease patients.

BACKGROUND: Administration of safe and effective iron therapy in patients with chronic kidney disease is a time consuming process. This phase II clinical trial studied ferumoxytol, a semi-synthetic carbohydrate-coated iron oxide administered by rapid intravenous injection to anemic chronic kidney disease patients (predialysis or undergoing peritoneal dialysis). METHODS: Inclusion criteria included hemoglobin < or =12.5 g/dL and transferrin saturation < or =35%. Twenty-one adult patients were randomized to receive ferumoxytol in a regimen of 4 doses of 255 mg iron in 2 weeks or 2 doses of 510 mg iron in 1 to 2 weeks. Ferumoxytol was administered at a rate of up to 30 mg iron/sec. RESULTS: The maximum hemoglobin response following ferumoxytol administration occurred at 6 weeks, increasing from a baseline of 10.4 +/- 1.3 g/dL to 11.4 +/- 1.2 g/dL (P < 0.05). Ferritin increased from a baseline of 232 +/- 216 ng/mL to a maximum of 931 +/- 361 ng/mL at 2 weeks (P < 0.05), while the baseline transferrin saturation increased from 21 +/- 10% to 37 +/- 22% at 1 week (P < 0.05). Seven adverse events in 5 patients during this trial were deemed possibly related to ferumoxytol, none serious. These events included constipation, chills, tingling, a gastrointestinal viral syndrome, delayed pruritic erythematous rash, and transient pain at the injection site. CONCLUSION: Although larger studies are required, this small study demonstrates that ferumoxytol can be safe and effective in increasing iron stores, is associated with an increased hemoglobin response, and is well tolerated at a rapid infusion rate.

Pharmacokinetic study of ferumoxytol: a new iron replacement therapy in normal subjects and hemodialysis patients.

BACKGROUND: Currently available intravenous iron preparations are not ideal, either because of safety concerns or dose limitations. We investigated the safety and pharmacokinetics of ferumoxytol, a new iron replacement therapy, in normal subjects and hemodialysis patients. METHODS: In a randomized, double-blind, ascending-dose study in normal volunteers (n = 41), 6 subjects received placebo, and 8 subjects each received ferumoxytol, at 1, 2 or 4 mg iron/kg, injected at 60 mg iron/min. The remaining subjects received 4 mg iron/kg at injection rates of 90 (n = 3), 180 (n = 3) or 1,800 mg iron/min (n = 5). In the second, open-label, ascending-dose study, 20 hemodialysis patients received 125 or 250 mg of iron over 5 min. RESULTS: In normal subjects, the blood half-life of ferumoxytol increased with increasing dose from 9.3 to 14.5 h (p < 0.05) but not with increasing rate of injection. The drug half-life in hemodialysis patients was similar to normal subjects. Ferumoxytol was not removed with hemodialysis. Serum iron (p < 0.001), transferrin saturation (p < 0.001) and ferritin increased in both populations. No serious adverse events were attributable to ferumoxytol. CONCLUSION: Ferumoxytol was well tolerated in this study. Its pharmacokinetic properties and simplicity of administration suggest that it will be an attractive form of iron replacement therapy.

Molecular mapping of the Goodpasture's epitope for glomerulonephritis.

Goodpasture's syndrome is an autoimmune disease characterized by pulmonary hemorrhage, glomerulonephritis, and antiglomerular basement membrane (GBM) antibodies. We have studied a rat model with chimeric proteins (CPs) consisting of portions of the nephritogenic non-collagenous domain of alpha3 type IV collagen (alpha3(IV)NC1) and non-nephritogenic alpha1(IV)NC1. CPs with aminoterminal alpha3 that contains the major epitope for Goodpasture antibody binding induced EAG. We next immunized with D3, an alpha1(IV)NC1 CP with 69AA of alpha3(IV)NC1 (binds Goodpasture sera), D4, the D3 construct shortened by 4 AA (nonbinding), P9 and P10, single AA mutants (nonbinding) and S2, an alpha1(IV)NC1 with nine AA of alpha3(IV)NC1 (binding). GBM, S2 and D3 induced EAG. GBM immunized rats had intense IgG deposits but S2 and D3 rats had minimal deposits. A 13 mer rat peptide encompassing the aminoterminal site induced EAG sans antibody, while peptides not encompassing the region failed to induce GN. Asparagine at position 19 rather than isoleucine was essential for disease induction. These studies define critical limited AA sequences of alpha3(IV)NC1 associated with glomerulonephritis without antibody, and demonstrate that this region contains a T-cell epitope responsible for induction of glomerulonephritis.