A Study of Neuromyelitis Optica Spectrum Disorders (NMOSD): Disease Pattern Based on Antibody Status.

Introduction: Neuromyelitis optica (NMO) is a central demyelinating disorder, predominantly affecting the optic nerves and spinal cord and autoimmune basis. We aimed to analyze the clinical, laboratory, and imaging features associated with NMO spectrum disorders (NMOSD) according to the aquaporin 4 antibody (AQP4-Ab) serology status. Methods: The inclusion of the patients was based on the Wingerchuk criteria (2006) for NMO, known antibody status and has minimum 1-year follow-up. We analyzed and compared 46 patients with known antibody status. Results: AQP4-Ab positivity was 56.5%. The male to female ratio in the seropositive group was 1:7.7 and 1:1.2 in the seronegative group. The mean age of onset in seropositive patients was 36.8 years (vs 28.8 years in seronegative NMOSD patients). Clinical feature, cerebrospinal fluid (CSF) and magnetic resonance imaging (MRI) features were also different, but data from two subsets did not reach statistical significance. The relapse rate was higher in AQP4 positive NMOSD (84.6% vs 55% in the seronegative group). The recovery rate for AQP4 positive patients was poor (15%). Summary: We found differences in age, gender, and prognosis between the two groups. Antibody status may be a guiding factor in deciding the treatment approach during the first attack of NMOSD.

Negative Impact of Vestibular Suppressant Drugs on Provocative Positional Tests of BPPV: A Study from the Western Part of India.

AIMS: To study the impact of vestibular suppressant drugs (VSD) on provocative positional tests (PPT) in patients with benign paroxysmal positional vertigo (BPPV). SETTINGS AND DESIGN: A prospective case-control observational study. MATERIALS AND METHODS: Patients with a history suggestive of BPPV were tested for PPT. Patients with vertiginous symptoms and with nystagmus on PPT were classified as objective BPPV (O-BPPV, control group), while those without nystagmus with no alternate diagnosis were classified as subjective BPPV (S-BPPV, case group). Details of VSD treatment were noted in all the patients. In both groups, patients were instructed to discontinue VSD and were further assigned as the VSD and non-VSD subgroups. Patients were followed for 2 months with PPT every week. PPT positive patients were treated by vestibular rehabilitation maneuvers. STATISTICS: Student t-test with two-tailed, unpaired, was used for continuous scale and Chi-square test for categorical differences between the two groups. RESULTS: 295 consecutive BPPV patients were enrolled in the study, 55 in the S-BPPV group and 240 in the O-BPPV group. Significantly higher proportion of patients in the S-BPPV group were on VSD at presentation, 80.00% vs. 53.75% (OR 2.52; 95% CI: 1.30-4.86), P = 0.006. In an unadjusted analysis of the S-BPPV group following discontinuation of VSD, PPT became positive in 79.54% of patients as compared to 18.19% in the non-VSD group (OR 35.0; 95% CI: 6.2-197.3), P < 0.001. CONCLUSION: A higher proportion of S-BPPV patients were receiving VSD in comparison to O-BPPV at the initial visit. The PPT converted positive four times higher after ceasing the VSD in S-BPPV patients. STUDY DESIGN: Prospective case-control observational study.

Management of Cardiovascular Disease in Kidney Disease Study: Rationale and Design.

INTRODUCTION: Atherosclerosis, inflammation, and vascular stiffness are prominent interrelated risk factors contributing to the high incidence of cardiovascular disease (CVD) in patients with CKD. Conventional CVD management strategies in CKD largely target atherosclerotic CVD and have had a limited impact on the cardiovascular mortality in this population. Multiple in vivo and in vitro studies and epidemiological evidence from the rheumatologic cohorts have shown that low-dose hydroxychloroquine has beneficial effects on inflammation, endothelial function, insulin sensitivity, and metabolic syndrome. Our recent proof-of-concept animal study showed that hydroxychloroquine has marked protection against atherosclerosis and vascular stiffness. We hypothesize that hydroxychloroquine has the potential to provide significant cardiovascular benefits in patients with CKD. METHODS: The Management of Cardiovascular disease in Kidney disease study (NCT03636152) is a phase 2B, randomized, double-blind, placebo-controlled trial evaluating the effects of low-dose hydroxychloroquine therapy on the parameters of atherosclerosis, inflammation, and vascular stiffness in patients with CKD. The study plans to enroll 100 CKD patients estimated to be at high cardiovascular risk by a combination of low estimated glomerular filtration rate and albuminuria and treat them for 18 months with hydroxychloroquine or placebo in 1:1 allocation. RESULTS: The study will assess the change in the total carotid plaque volume as measured by serial noncontrast carotid MRI as the primary outcome and the serial changes in plasma inflammation markers, vascular stiffness, renal function, and the composition characteristics of the carotid plaque as secondary outcome measures. DISCUSSION/CONCLUSION: The results of this trial will provide the proof-of-applicability for hydroxychloroquine in the CVD in CKD. If positive, this trial should lead to phase-3 trials with clinical end points for this potentially transformative, novel, and inexpensive therapy for CVD in CKD.

Home run-results of a chronic kidney disease Telemedicine Patient Education Study.

BACKGROUND: Chronic kidney disease (CKD) incidence is increasing and associated mortality and morbidity are high. Educating patients is effective in delaying progression and establishing optimal renal replacement therapy (RRT). Tele-education/telemedicine (TM) can be an effective tool to provide such education, but there are no available data quantifying its effectiveness. We attempted to establish such evidence correlating the effect of education in patient choices and with the start of actual RRT. We present results from a 3-year pilot study evaluating the effectiveness of comprehensive predialysis education (CPE) through TM for CKD patients compared with a standard care group [face to face (FTF)]. The patient's ability to choose RRT was the primary endpoint. METHODS: This was a randomized controlled study providing CPE over three classes at nine sites (one FTF and eight TM). Three assessment tools were utilized to compare groups: CKD knowledge, literacy and quality of life. RESULTS: A total of 47.1% of FTF and 52.2% of TM patients reported not having enough information to choose a modality. This decreased by the third visit (FTF 7.4%, TM 13.2%). Home modality choices more than doubled in both groups (FTF 25.8-67.7%, TM 22.2-50.1%). In patients that completed one visit and needed to start RRT, 47% started on a home modality or received a pre-emptive transplant (home hemodialysis 6%, peritoneal dialysis 38%, transplant 3%). CONCLUSIONS: Results show almost 90% (TM 87%, FTF 95%) of the attendees could choose a modality after education. Home modality choices doubled. Patients were able to make an informed choice regardless of the modality of education.

Autophagy Function and Regulation in Kidney Disease.

Autophagy is a dynamic process by which intracellular damaged macromolecules and organelles are degraded and recycled for the synthesis of new cellular components. Basal autophagy in the kidney acts as a quality control system and is vital for cellular metabolic and organelle homeostasis. Under pathological conditions, autophagy facilitates cellular adaptation; however, activation of autophagy in response to renal injury may be insufficient to provide protection, especially under dysregulated conditions. Kidney-specific deletion of Atg genes in mice has consistently demonstrated worsened acute kidney injury (AKI) outcomes supporting the notion of a pro-survival role of autophagy. Recent studies have also begun to unfold the role of autophagy in progressive renal disease and subsequent fibrosis. Autophagy also influences tubular cell death in renal injury. In this review, we reported the current understanding of autophagy regulation and its role in the pathogenesis of renal injury. In particular, the classic mammalian target of rapamycin (mTOR)-dependent signaling pathway and other mTOR-independent alternative signaling pathways of autophagy regulation were described. Finally, we summarized the impact of autophagy activation on different forms of cell death, including apoptosis and regulated necrosis, associated with the pathophysiology of renal injury. Understanding the regulatory mechanisms of autophagy would identify important targets for therapeutic approaches.

Long-term Adverse Events Associated With Acute Kidney Injury.

Acute kidney injury (AKI) occurs in approximately 10% to 15% of hospital-admitted patients and is associated with in-hospital mortality of 50% in patients requiring renal replacement therapy. Recently, multiple observational studies have demonstrated that patients who survive AKI have significant long-term consequences including cardiovascular events, progression to advanced-stage chronic kidney disease (CKD), and mortality. A direct link between AKI and CKD is provided by studies that demonstrate that some patients with normal renal function who develop AKI requiring dialysis never recover. In addition, in a large pediatric AKI population, 10% of the cohort developed CKD within 1 to 3 years. In a systemic review and meta-analysis in which 13 cohort studies were analyzed, patients with AKI had a hazard ratio (HR) of 8.8 for developing CKD, HR of 3.1 of developing end-stage kidney disease, and HR of 2.0 for mortality. AKI was also independently associated with risk for cardiovascular disease and congestive heart failure. These studies indicate that AKI is associated with important, long-term consequences and that AKI has become an important contributor to the end-stage kidney disease population. Prospective ongoing studies will better define the cause-effect relationship and delineate potential biomarkers that would identify AKI patients at risk for CKD, cardiovascular events, and mortality.

Effects of a Comprehensive Predialysis Education Program on the Home Dialysis Therapies: A Retrospective Cohort Study.

BACKGROUND: Improvement in the rates of home dialysis has been a desirable but difficult-to-achieve target for United States nephrology. Provision of comprehensive predialysis education (CPE) in institutes with established home dialysis programs has been shown to facilitate a higher home dialysis choice amongst chronic kidney disease (CKD) patients. Unfortunately, limited data have shown the efficacy of such programs in the United States or in institutes with small home dialysis (HoD) programs. METHODS: We report the retrospective findings examining the efficacy of a CPE program in the early period after its establishment, with reference to its impact on the choice and growth of a small HoD program. RESULTS: Over the initial 22 months since its inception, 108 patients were enrolled in the CPE clinic. Seventy percent of patients receiving CPE chose HoD, of which 55% chose peritoneal dialysis (PD) and 15% chose home hemodialysis (HHD). Rates of HoD choice were similar across the spectrum of socio-economic variables. Of just over half (54.6%) of those choosing to return for more than 1 session, 25.3%, changed their modality preference after the first education session, and nearly all reached a final modality selection by the end of the third visit. Initiation of the CPE program resulted in a 216% growth in HoD census over the same period and resulted in near doubling of HoD prevalence to 38% of all dialysis patients. CONCLUSIONS: Comprehensive patient education improves the choice and prevalence of HoD therapies. We further find that 3 sessions of CPE may provide needed resources for the large majority of subjects for adequate decision-making.

Carbamylated Low-Density Lipoprotein (cLDL)-Mediated Induction of Autophagy and Its Role in Endothelial Cell Injury.

Patients with chronic kidney disease (CKD) have high risk of cardiovascular complications. Plasma levels of carbamylated proteins produced by urea-derived isocyanate or thiocyanate are elevated in CKD patients and that they are significant predictors of cardiovascular events and all-cause mortality. Carbamylated LDL (cLDL) has pro-atherogenic properties and is known to affect major biological processes relevant to atherosclerosis including endothelial cell injury. The underlying mechanisms of cLDL-induced endothelial cell injury are not well understood. Although autophagy has been implicated in atherosclerosis, cLDL-mediated induction of autophagy and its role in endothelial cell injury is unknown. Our studies demonstrate that human coronary artery endothelial cells (HCAECs) respond to cLDL by specific induction of key autophagy proteins including LC3-I, beclin-1, Atg5, formation of lipid-conjugated LC3-II protein, and formation of punctate dots of autophagosome-associated LC3-II. We demonstrated that autophagy induction is an immediate response to cLDL and occurred in a dose and time-dependent manner. Inhibition of cLDL-induced autophagy by a specific siRNA to LC3 as well as by an autophagy inhibitor provided protection from cLDL-induced cell death and DNA fragmentation. Our studies demonstrate that autophagy plays an important role in cLDL-mediated endothelial cell injury and may provide one of the underlying mechanisms for the pathogenesis of cLDL-induced atherosclerosis in CKD patients.

Combined Central and Peripheral Demyelination.

Demyelinating disorders are very common, but remains isolated to the part of nervous system they involve. However, infrequently, combined involvement of central and peripheral nervous system with demyelinating process have been described. We report one such rare case, with possible theories of common etiological basis. We present a middle aged male patient with Chronic Inflammatory Demyelinating Polyneuropathy(CIDP), who responded to immuno-modulation. Subsequently, he developed Acute Transverse Myelitis (ATM). Recently a common substrate protein, NF186 has been described as responsible for this rare clinical entity.

Association of Urinary Biomarkers of Inflammation, Injury, and Fibrosis with Renal Function Decline: The ACCORD Trial.

BACKGROUND AND OBJECTIVES: Current measures for predicting renal functional decline in patients with type 2 diabetes with preserved renal function are unsatisfactory, and multiple markers assessing various biologic axes may improve prediction. We examined the association of four biomarker-to-creatinine ratio levels (monocyte chemotactic protein-1, IL-18, kidney injury molecule-1, and YKL-40) with renal outcome. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We used a nested case-control design in the Action to Control Cardiovascular Disease Trial by matching 190 participants with ≥40% sustained eGFR decline over the 5-year follow-up period to 190 participants with ≤10% eGFR decline in a 1:1 fashion on key characteristics (age within 5 years, sex, race, baseline albumin-to-creatinine ratio within 20 µg/mg, and baseline eGFR within 10 ml/min per 1.73 m(2)), with ≤10% decline. We used a Mesoscale Multiplex Platform and measured biomarkers in baseline and 24-month specimens, and we examined biomarker associations with outcome using conditional logistic regression. RESULTS: Baseline and 24-month levels of monocyte chemotactic protein-1-to-creatinine ratio levels were higher for cases versus controls. The highest quartile of baseline monocyte chemotactic protein-1-to-creatinine ratio had fivefold greater odds, and each log increment had 2.27-fold higher odds for outcome (odds ratio, 5.27; 95% confidence interval, 2.19 to 12.71 and odds ratio, 2.27; 95% confidence interval, 1.44 to 3.58, respectively). IL-18-to-creatinine ratio, kidney injury molecule-1-to-creatinine ratio, and YKL-40-to-creatinine ratio were not consistently associated with outcome. C statistic for traditional predictors of eGFR decline was 0.70, which improved significantly to 0.74 with monocyte chemotactic protein-1-to-creatinine ratio. CONCLUSIONS: Urinary monocyte chemotactic protein-1-to-creatinine ratio concentrations were strongly associated with sustained renal decline in patients with type 2 diabetes with preserved renal function.

Autophagy in acute kidney injury.

Autophagy is a conserved multistep pathway that degrades and recycles damaged organelles and macromolecules to maintain intracellular homeostasis. The autophagy pathway is upregulated under stress conditions including cell starvation, hypoxia, nutrient and growth-factor deprivation, endoplasmic reticulum stress, and oxidant injury, most of which are involved in the pathogenesis of acute kidney injury (AKI). Recent studies demonstrate that basal autophagy in the kidney is vital for the normal homeostasis of the proximal tubules. Deletion of key autophagy proteins impaired renal function and increased p62 levels and oxidative stress. In models of AKI, autophagy deletion in proximal tubules worsened tubular injury and renal function, highlighting that autophagy is renoprotective in models of AKI. In addition to nonselective sequestration of autophagic cargo, autophagy can facilitate selective degradation of damaged organelles, particularly mitochondrial degradation through the process of mitophagy. Damaged mitochondria accumulate in autophagy-deficient kidneys of mice subjected to ischemia-reperfusion injury, but the precise mechanisms of regulation of mitophagy in AKI are not yet elucidated. Recent progress in identifying the interplay of autophagy, apoptosis, and regulated necrosis has revived interest in examining shared pathways/molecules in this crosstalk during the pathogenesis of AKI. Autophagy and its associated pathways pose potentially unique targets for therapeutic interventions in AKI.

Proteolytic processing and inactivation of CCL2/MCP-1 by meprins.

Monocyte chemotactic protein 1 (CCL2/MCP-1) is a small chemokine involved in the recruitment and trafficking of mononuclear immune cells to inflammation sites. Our studies demonstrate that the metalloendopeptidases meprin A (purified from kidney cortex), recombinant meprin α, and recombinant meprin ß can all process CCL2/MCP-1. The cleavage sites were determined by amino acid sequencing and mass spectrometry analysis of the generated products, and the biological activity of the products was evaluated by chemotactic migration assay using THP-1 cells. The cleavage sites generated by the meprin isoforms revealed that meprin A and meprin α cleaved the N-terminal domain of mouse CCL2/MCP-1 at the Asn6 and Ala7 bond, resulting in significant reduction in the chemotactic activity of the cleaved CCL2/MCP-1. Meprin ß was unable to cleave the N-terminus of mouse CCL2/MCP-1 but cleaved the C-terminal region between Ser74 and Glu75. Human CCL2/MCP-1 that lacks the murine C-terminal region was also cleaved by meprin α at the N-terminus resulting in significant loss of CCL2/MCP-1 biological activity, whereas meprin ß did not affect the biological activity. These studies suggest that meprin α and meprin ß may play important roles in regulating the CCL2/MCP-1 chemokine activity during inflammation.

Impact of Hydroxychloroquine on Atherosclerosis and Vascular Stiffness in the Presence of Chronic Kidney Disease.

Cardiovascular disease is the largest cause of morbidity and mortality among patients with chronic kidney disease (CKD) and end-stage kidney disease, with nearly half of all deaths attributed to cardiovascular disease. Hydroxychloroquine (HCQ), an anti-inflammatory drug, has been shown to have multiple pleiotropic actions relevant to atherosclerosis. We conducted a proof-of-efficacy study to evaluate the effects of hydroxychloroquine in an animal model of atherosclerosis in ApoE knockout mice with and without chronic kidney disease. Forty male, 6-week-old mice were divided into four groups in a 2 x 2 design: sham placebo group; sham treatment group; CKD placebo group; and CKD treatment group. CKD was induced by a two-step surgical procedure. All mice received a high-fat diet through the study duration and were sacrificed after 16 weeks of therapy. Mice were monitored with ante-mortem ultrasonic echography (AUE) for atherosclerosis and vascular stiffness and with post-mortem histology studies for atherosclerosis. Therapy with HCQ significantly reduced the severity of atherosclerosis in CKD mice and sham treated mice. HCQ reduced the area of aortic atherosclerosis on en face examination by approximately 60% in HCQ treated groups compared to the non-treated groups. Additionally, therapy with HCQ resulted in significant reduction in vascular endothelial dysfunction with improvement in vascular elasticity and flow patterns and better-preserved vascular wall thickness across multiple vascular beds. More importantly, we found that presence of CKD had no mitigating effect on HCQ's anti-atherosclerotic and vasculoprotective effects. These beneficial effects were not due to any significant effect of HCQ on inflammation, renal function, or lipid profile at the end of 16 weeks of therapy. This study, which demonstrates structural and functional protection against atherosclerosis by HCQ, provides a rationale to evaluate its use in CKD patients. Further studies are needed to define the exact mechanisms through which HCQ confers these benefits.

Evidence Suggesting a Role of Iron in a Mouse Model of Nephrogenic Systemic Fibrosis.

Nephrogenic systemic fibrosis is associated with gadolinium contrast exposure in patients with reduced kidney function and carries high morbidity and mortality. We have previously demonstrated that gadolinium contrast agents induce in vivo systemic iron mobilization and in vitro differentiation of peripheral blood mononuclear cells into ferroportin (iron exporter)-expressing fibrocytic cells. In the present study we examined the role of iron in a mouse model of nephrogenic systemic fibrosis. Chronic kidney disease was induced in 8-week-old male Balb/C mice with a two-step 5/6 nephrectomy surgery. Five groups of mice were studied: control (n = 5), sham surgery control (n = 5), chronic kidney disease control (n = 4), chronic kidney disease injected with 0.5 mmol/kg body weight of Omniscan 3 days per week, for a total of 10 injections (n = 8), and chronic kidney disease with Omniscan plus deferiprone, 125 mg/kg, in drinking water (n = 9). Deferiprone was continued for 16 weeks until the end of the experiment. Mice with chronic kidney disease injected with Omniscan developed skin changes characteristic of nephrogenic systemic fibrosis including hair loss, reddening, ulceration, and skin tightening by 10 to 16 weeks. Histopathological sections demonstrated dermal fibrosis with increased skin thickness (0.25±0.06 mm, sham; 0.34±+0.3 mm, Omniscan-injected). Additionally, we observed an increase in tissue infiltration of ferroportin-expressing, fibrocyte-like cells accompanied by tissue iron accumulation in the skin of the Omniscan-treated mice. The deferiprone-treated group had significantly decreased skin thickness (p<0.05) and significantly decreased dermal fibrosis compared to the Omniscan-only group. In addition, iron chelation prevented tissue infiltration of ferroportin-expressing, fibrocyte-like cells. Our in vitro experiments demonstrated that exposure to Omniscan resulted in the release of catalytic iron and this was prevented by the iron chelator deferiprone. Deferiprone inhibited the differentiation of human peripheral blood mononuclear cells into ferroportin-expressing cells by immunohistochemical staining and western blot analysis. Our studies support an important role of iron in the pathophysiology of gadolinium chelate toxicity and nephrogenic systemic fibrosis.

Recent advances in understanding the pathogenesis of atherosclerosis in CKD patients.

A need exists for developing new therapies to improve cardiovascular outcomes in end-stage kidney disease. Three new areas that address novel pathophysiological mechanisms and/or therapeutic approaches toward cardiovascular events in chronic kidney disease patients include the use of an anti-inflammatory agent, the role of catalytic iron, and protein carbamylation. In preliminary studies, hydroxychloroquine, which has multiple anti-inflammatory properties, preserved vascular compliance for the aorta and major vessels, as well as reduced the extent of severity of atherosclerosis in ApoE-/- mice. The ability of iron to rapidly and reversibly cycle between 2 oxidation states makes iron potentially hazardous by enabling it to participate in the generation of powerful oxidant species. We have shown that high catalytic iron in the general population is associated with a 4-fold increase in prevalent cardiovascular disease (CVD), even after accounting for traditional risk factors. In addition, the highest levels of catalytic iron are present in dialysis patients and, more specifically, patients with prevalent CVD have several-fold higher catalytic iron levels compared with controls without CVD. These data suggest the utility of iron chelators for preventing and treating CVD in patients with chronic kidney disease and should be further investigated. Carbamylation of proteins results from nonenzymatic chemical modification by isocyanic acid derived from urea and an alternative route, the myeloperoxidase-catalyzed oxidation of thiocyanate. We have shown carbamylated low-density lipoprotein to have all the major biological effects relevant to atherosclerosis including endothelial cell injury, increased expression of cell adhesion molecules, and vascular smooth muscle cell proliferation. In 2 separate clinical studies, plasma levels of carbamylated protein independently predicted an increased risk of CVD and death.

Inhibition of cytochrome P450 2E1 and activation of transcription factor Nrf2 are renoprotective in myoglobinuric acute kidney injury.

Rhabdomyolysis accounts for ∼10% of acute kidney injuries. In glycerol-induced myoglobinuric acute kidney injury, we found an increase in the nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear protein, a key redox-sensitive transcription factor, and Nrf2-regulated genes and proteins including upregulation of heme oxygenase-1. In in vitro studies, pretreatment of LLC-PK1 cells with an activator of Nrf2 before myoglobin exposure significantly decreased oxidant generation and cytotoxicity, whereas Nrf2 inhibition and gene silencing exacerbated the injury. Chlormethiazole, a specific CYP2E1 transcription inhibitor, prevented an increase in catalytic iron in the kidneys, decreased oxidative stress, blocked nuclear translocation of the Nrf2 protein, decreased heme oxygenase-1 upregulation, and provided functional and histological protection against acute kidney injury. CYP2E1 inhibitors and gene silencing in renal tubular epithelial cells significantly decreased reactive oxygen species generation and provided marked protection against myoglobin-induced cytotoxicity. Thus, during CYP2E1-induced oxidative stress, the transcription factor Nrf2 has a pivotal role in the early adaptive response. Inhibition of CYP2E1 coupled with the prior induction of Nrf2 may be a valuable tool to reduce CYP2E1-mediated rhabdomyolysis-induced acute kidney injury.

ADAM10 is the major sheddase responsible for the release of membrane-associated meprin A.

Meprin A, composed of α and ß subunits, is a membrane-bound metalloproteinase in renal proximal tubules. Meprin A plays an important role in tubular epithelial cell injury during acute kidney injury (AKI). The present study demonstrated that during ischemia-reperfusion-induced AKI, meprin A was shed from proximal tubule membranes, as evident from its redistribution toward the basolateral side, proteolytic processing in the membranes, and excretion in the urine. To identify the proteolytic enzyme responsible for shedding of meprin A, we generated stable HEK cell lines expressing meprin ß alone and both meprin α and meprin ß for the expression of meprin A. Phorbol 12-myristate 13-acetate and ionomycin stimulated ectodomain shedding of meprin ß and meprin A. Among the inhibitors of various proteases, the broad spectrum inhibitor of the ADAM family of proteases, tumor necrosis factor-α protease inhibitor (TAPI-1), was most effective in preventing constitutive, phorbol 12-myristate 13-acetate-, and ionomycin-stimulated shedding of meprin ß and meprin A in the medium of both transfectants. The use of differential inhibitors for ADAM10 and ADAM17 indicated that ADAM10 inhibition is sufficient to block shedding. In agreement with these results, small interfering RNA to ADAM10 but not to ADAM9 or ADAM17 inhibited meprin ß and meprin A shedding. Furthermore, overexpression of ADAM10 resulted in enhanced shedding of meprin ß from both transfectants. Our studies demonstrate that ADAM10 is the major ADAM metalloproteinase responsible for the constitutive and stimulated shedding of meprin ß and meprin A. These studies further suggest that inhibiting ADAM 10 activity could be of therapeutic benefit in AKI.

Challenges and advances in the treatment of AKI.

Treating or preventing AKI requires treating or preventing a rise in serum creatinine as well as the immediate and remote clinical consequences associated with AKI. Because a substantial number of patients with AKI progress to ESRD, identifying patients likely to progress and halting progression are important goals for treating AKI. Many therapies for AKI are being developed, including RenalGuard Therapy, which aims to maintain high urine output; α-melanocyte-stimulating hormone, with anti-inflammatory and antiapoptotic activities; alkaline phosphatase, which detoxifies proinflammatory substances; novel, small interfering RNA, directed at p53 activation; THR-184, a peptide agonist of bone morphogenetic proteins; removal of catalytic iron, important in free-radical formation; and cell-based therapies, including mesenchymal stem cells in vivo and renal cell therapy in situ. In this review, we explore what treatment of AKI really means, discuss the emerging therapies, and examine the windows of opportunity for treating AKI. Finally, we provide suggestions for accelerating the pathways toward preventing and treating AKI, such as establishing an AKI network, implementing models of catalytic philanthropy, and directing a small percentage of the Medicare ESRD budget for developing therapies to prevent and treat AKI and halt progression of CKD.

Carbamylated-oxidized LDL: proatherosclerotic effects on endothelial cells and macrophages.

AIM: Both oxidized LDL and carbamylated LDL are considered important for initiating atherosclerosis in patients with end-stage kidney disease through vascular endothelial cell dysfunction or injury. However their effects on each other and their relationship related to pro-atherosclerotic effects on endothelial cells and macrophages have not been investigated. In this study, we analyzed the competition between LDL carbamylation and oxidation, tested biological effects of carbamylated-oxidized LDL (coxLDL) toward the endothelial cells, assessed its ability to cause foam cell development, and determined the roles of scavenger receptors in this process. METHODS: Cross-competition between carbamylation and oxidation of LDL particles was tested using cell-free fluorescent ligand-receptor assay. Pro-atherogenic properties (cell proliferation, cytotoxicity, and foam cell formation) of all LDL isoforms were tested in vitro and ex vivo using endothelial cells and peritoneal macrophages. In addition, coxLDL was assessed in human sera and in vivo atherosclerotic plaques which were developed in mouse model of uremia-induced atherosclerosis. RESULTS: Our data suggest that there is potential competition between carbamylation and oxidation of LDL, and that oxidation is a much stronger inhibitor of carbamylation than vice versa. coxLDL is highly cytotoxic to endothelial cells and strongly induce their proliferation measured by DNA synthesis. All three tested LDL isoforms demonstrated strong ability for transformation of primary mouse peritoneal macrophages to foam cells using predominantly CD36 scavenger receptor. coxLDL was the most potent inducer of foam cell development and macrophages/foam cell injury assessed by cell count and TUNEL, respectively. Finally, LDL particles modified by oxidation and carbamylation were detected in blood and shown to co-localize in atherosclerotic plaques in mice. CONCLUSION: Our study demonstrated that LDL particles can be simultaneously carbamylated and oxidized and modifications are likely coexisting in the same LDL particle. We also demonstrated proatherosclerotic properties of coxLDL and proposed its role in atherosclerosis.