Tipu S. Puri

C5a promotes development of experimental lupus nephritis which can be blocked with a specific receptor antagonist.

The MRL/lpr murine SLE model has widespread complement activation and deposition of complement fragments in affected tissues. The potent anaphylatoxin C5a has the potential to play a key role in the pathogenesis of lupus nephritis. We found that renal expression of C5aR mRNA and protein was significantly increased in MRL/lpr mice compared to control MRL/+ mice. To examine the role of C5a signaling through C5aR, a specific small molecule antagonist (a) of C5aR was administered continuously to MRL/lpr mice from 13 to 19 wks of age. Littermate controls were given vehicle alone. The progressive impairment in renal function exhibited in the control group was prevented by C5aRa treatment. Infiltration of neutrophils and macrophages into kidneys was significantly reduced in animals treated with C5aRa compared to controls. Furthermore, renal expression of IL‐1β and MIP‐2 mRNA as well as the extent of apoptosis were significantly decreased with blockade of C5aR, indicating their dependence upon signals delivered through C5aR. Thus, pharmacological blockade of C5aR reduces disease manifestations in experimental lupus nephritis. These data support an important role for the C5a anaphylatoxin in lupus nephritis, and that blockade of C5aR represents a potentially viable treatment for human lupus nephritis.

Vascular Remodeling and Arterial Calcification Are Directly Mediated by S100A12 (EN-RAGE) in Chronic Kidney Disease

Background: The proinflammatory cytokine S100A12 (also known as EN-RAGE) is associated with cardiovascular morbidity and mortality in hemodialysis patients. In the cur- rent study, we tested the hypothesis that S100A12 expressed in vascular smooth muscle in nonatherosclerosis-prone C57BL/6J mice on normal rodent chow diet, but exposed to the metabolic changes of chronic kidney disease (CKD), would develop vascular disease resembling that observed in patients with CKD. Methods: CKD was induced in S100A12 transgenic mice and wild-type littermate mice not expressing human S100A12 by surgical ligation of the ureters. The aorta was analyzed after 7 weeks of elevated BUN (blood urea nitrogen), and cultured aortic smooth muscle cells were studied. Results: We found enhanced vascular medial calcification in S100A12tg mice subjected to CKD. Vascular calcification was mediated, at least in part, by activation of the receptor for S100A12, RAGE (receptor for advanced glycation endproducts), and by enhanced oxidative stress, since inhibition of NADPH-oxidase Nox1 and limited access of S100A12 to RAGE attenuated the calcification and gene expression of osteoblastic genes in cultured vascular smooth muscle cells. Conclusion: S100A12 augments CKD-triggered osteogenesis in murine vasculature, reminiscent of features associated with enhanced vascular calcification in patients with chronic and end-stage kidney disease.

Chronic kidney disease induced in mice by reversible unilateral ureteral obstruction is dependent on genetic background.

Chronic kidney disease (CKD) begins with renal injury; the progression thereafter depends upon a number of factors, including genetic background. Unilateral ureteral obstruction (UUO) is a well-described model of renal fibrosis and as such is considered a model of CKD. We used an improved reversible unilateral ureteral obstruction (rUUO) model in mice to study the strain dependence of development of CKD after obstruction-mediated injury. C57BL/6 mice developed CKD after reversal of three or more days of ureteral obstruction as assessed by blood urea nitrogen (BUN) measurements (>40 mg/dl). In contrast, BALB/c mice were resistant to CKD with up to 10 days ureteral obstruction. During rUUO, C57BL/6 mice exhibited pronounced inflammatory and intrinsic proliferative cellular responses, disruption of renal architecture, and ultimately fibrosis. By comparison, BALB/c mice had more controlled and measured extrinsic and intrinsic responses to injury with a return to normal within several weeks after release of ureteral obstruction. Our findings provide a model that allows investigation of the genetic basis of events during recovery from injury that contribute to the development of CKD.

S100/Calgranulin-Mediated Inflammation Accelerates Left Ventricular Hypertrophy and Aortic Valve Sclerosis in Chronic Kidney Disease in a Receptor for Advanced Glycation End Products–Dependent Manner

Objective—S100A12 and fibroblast growth factor 23 are biomarkers of cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). We tested the hypothesis that human S100/calgranulin would accelerate cardiovascular disease in mice subjected to CKD. Approach and Results—A bacterial artificial chromosome of the human S100/calgranulin gene cluster containing the genes and regulatory elements for S100A8, S100A9, and S100A12 was expressed in C57BL/6J mouse (hBAC-S100) to generate a novel humanized mouse model. CKD was induced by ureteral ligation, and hBAC-S100 mice and wild-type mice were studied after 10 weeks of chronic uremia. hBAC-S100 mice with CKD showed increased fibroblast growth factor 23 in the hearts, left ventricular hypertrophy, diastolic dysfunction, focal cartilaginous metaplasia, and calcification of the mitral and aortic valve annulus together with aortic valve sclerosis. This phenotype was not observed in wild-type mice with CKD or in hBAC-S100 mice lacking the receptor for advanced glycation end products with CKD, suggesting that the inflammatory milieu mediated by S100/receptor for advanced glycation end products promotes pathological cardiac hypertrophy in CKD. In vitro, inflammatory stimuli including interleukin-6, tumor necrosis factor-&agr;, lipopolysaccarides, or serum from hBAC-S100 mice upregulated fibroblast growth factor 23 mRNA and protein in primary murine neonatal and adult cardiac fibroblasts. Conclusions—Myeloid-derived human S100/calgranulin is associated with the development of cardiac hypertrophy and ectopic cardiac calcification in a receptor for advanced glycation end products–dependent manner in a mouse model of CKD. We speculate that fibroblast growth factor 23 produced by cardiac fibroblasts in response to cytokines may act in a paracrine manner to accelerate left ventricular hypertrophy and diastolic dysfunction in hBAC-S100 mice with CKD.

Characterization of novel VEGF (vascular endothelial growth factor)-C splicing isoforms from mouse

VEGF (vascular endothelial growth factor)-C is a major growth factor implicated in various physiological processes, such as angiogenesis and lymphangiogenesis. In the present paper, we report the identification of three short VEGF-C splicing isoforms (VEGF-C62, VEGF-C129 and VEGF-C184) from immortalized mouse kidney PTECs (proximal tubular epithelial cells). Semi-quantitative RT (reverse transcription)-PCR analysis showed these isoforms were universally expressed to varying degrees in different tissues with high expression levels in the kidney. In immortalized PTECs and podocytes, VEGF-C62 can activate phosphorylation of FAK (focal adhesion kinase) and promote cell adhesion to substratum. Cell survival was also increased by VEGF-C62 treatment in the absence of serum. VEGF-C62 can also reduce cell proliferation in PTECs and podocytes. Nucleolin was one of the proteins that associated with VEGF-C62 in pull-down assays using GST (glutathione transferase) fusion proteins as bait, indicating different protein binding requirements for VEGF-C62 compared with VEGF-C. In conclusion, these newly identified VEGF-C isoforms represent a new class of proteins, which are potentially involved in epithelial cell adhesion and proliferation through novel receptor pathways.

Longitudinal changes in MRI markers in a reversible unilateral ureteral obstruction mouse model: Preliminary experience

To evaluate longitudinal changes in renal oxygenation and diffusion measurements in a model of reversible unilateral ureteral obstruction (rUUO) which has been shown to induce chronic renal functional deficits in a strain dependent way. C57BL/6 mice show higher degree of functional deficit compared with BALB/c mice. Because hypoxia and development of fibrosis are associated with chronic kidney diseases and are responsible for progression, we hypothesized that MRI measurements would be able to monitor the longitudinal changes in this model and will show strain dependent differences in response. Here blood oxygenation level dependent (BOLD) and diffusion MRI measurements were performed at three time points over a 30 day period in mice with rUUO.

Contrasting Effects of Systemic Monocyte/Macrophage and CD4+ T Cell Depletion in a Reversible Ureteral Obstruction Mouse Model of Chronic Kidney Disease

Using a reversible UUO model (rUUO), we have demonstrated that C57BL/6 mice are susceptible to development of CKD after obstruction-mediated kidney injury while BALB/c mice are resistant. We hypothesized that selective systemic depletion of subpopulations of inflammatory cells during injury or repair might alter the development of CKD. To investigate the impact of modification of Th-lymphocytes or macrophage responses on development of CKD after rUUO, we used an anti-CD4 antibody (GK1.5) or liposomal clodronate to systemically deplete CD4+ T cells or monocyte/macrophages, respectively, prior to and throughout the rUUO protocol. Flow cytometry and immunohistochemistry confirmed depletion of target cell populations. C57BL/6 mice treated with the GK1.5 antibody to deplete CD4+ T cells had higher BUN levels and delayed recovery from rUUO. Treatment of C57BL/6 mice with liposomal clodronate to deplete monocyte/macrophages led to a relative protection from CKD as assessed by BUN values. Our results demonstrate that modulation of the inflammatory response during injury and repair altered the susceptibility of C57BL/6 mice to development of CKD in our rUUO model.

Title Page. Formal Assessment of Donor Kidney Function Should Be Mandatory

other chronic conditions post-kidney donation. Anything else is trying to be heroic and potentially jeopardizing the health of the donor. Clearly, the authors do not see a problem with using a donor at risk as long as iothalamate GFR is 1 80 ml/min/1.73 m 2 . We firmly believe that if donor safety is a priority, then any donor at risk, irrespective of GFR, should not be considered a donor. In specific instances, patients who are obese or have glucose intolerance, may be considered for standard treatment and later considered for kidney donation. However, accepting these patients with risk factors because iothalamate GFR is 1 80 ml/min/1.73 m 2 is simply not acceptable, nor ethical, knowing the cumulative risk of chronic disease these factors may pose. One can argue that the risk of developing kidney failure in a donor who developed diabetes or hypertension later in life does not depend on whether the donor has one or two kidneys. This is probably true, but we have no scientific evidence to back this up, and therefore absolute caution is necessary. We believe that the currently available creatinine clearance and eGFR methods are easy to use, have no significant costs or side effects and the results should be within the normally accepted range ( 1 90 and ! 150 ml/min/1.73 m 2 ) in a ‘normal’ healthy individual for acceptance as a kidney donor. There is data to suggest that MDRD underestimates GFR at GFR 1 60 ml/min/1.73 m 2 , so the cutoff point of 90 ml/min/1.73 m 2 should pose no problem. In We read with interest the positive role of formal glomerular filtration (GFR) assessment of living kidney donors using radionuclide by Tan et al. [1] . Although they present a logical narrative of why formal assessment of GFR should be performed in all potential kidney donors, they fail to recognize that the kidney donor must be normal to ensure no immediate or long-term harm is incurred. Donor safety must always be the top priority and emotional issues around the growing waitlist, shortage of organs or both should not be an excuse to select suboptimal donors for increasing the donor pool. Patients in renal failure are already receiving some form of life-sustaining therapy and it is not rational to risk the health of another person for the sake of improving the quality of life of the recipient [2] . The authors wrote, ‘ We therefore recommend more accurate and rigorous testing of kidney function in donors who are compromised by middle or older age, hypertension or glucose intolerance. Such donors are prone to glomerulopenia, and hence at risk of developing progressive loss of kidney function following a halving of their nephron mass ’. In our opinion, we should not even consider these ‘compromised’ individuals as potential donors. Let us shoot straight and put an end to this ethical and emotional dilemma. A potential donor is either normal or not. Normal is defined as the absence of any chronic condition and risk factors for renal disease, hypertension, diabetes and Published online: February 18, 2011 Nephrology American Journal of