Alteration of the maximal renal water excretion capacity with kidney function and age in human

PURPOSE

The kidney's capability to concentrate and dilute urine is crucial to maintaining body fluid compartments and plasma osmolality. Advanced age and chronic kidney disease (CKD) result in decreased maximal urine concentration. Less is known regarding urine dilution ability. The primary purpose of this study was to determine the relationship between maximal renal water excretion and renal function, age, and gender in humans.

METHODS

This monocentric retrospective study includes patients referred to the Department of Clinical Physiology in Toulouse University Hospital to measure the glomerular filtration rate (mGFR) between April 2013 and February 2018. mGFR was assessed using inulin renal clearance and required ample hydration. We quantified the effects of age, gender and mGFR have on water excretion ability, which was assessed by minimal urinary osmolality (minUosm) and maximal free water clearance (maxCH2O).

RESULTS

666 patients were included (mean age 51 ± 14 years, 53% female). Mean mGFR was 82 ± 25 mL/min/1.73m2. MinUosm after hydration was higher in patients with renal insufficiency while maxCH2O was markedly lower. Age was also, with a weaker effect, associated with decreased in water excretion, independently of mGFR. MaxCH2O clearance was similar in both genders, whereas minUosm was lower in women, possibly resulting from a lower osmotic load.

DISCUSSION

This study shows a decrease in maximal urinary dilution capacity and free water clearance with CKD and age, without gender difference. These alterations are mild but must be considered when a significant water intake is required or in the case of hyponatremia.

CCL7 chemokine is a marker but not a therapeutic target of acute kidney injury

BACKGROUND

Chemokines orchestrate immune cells activation and infiltration during acute kidney injury (AKI).

OBJECTIVES

We aim to test whether deletion of C-C Chemokine Ligand 7 (CCL7), a small chemokine related to CCL2 (MCP-1), may modulate AKI development and progression toward kidney fibrosis.

METHOD

Expression of CCL7 was quantified in murine cortical tubular (MCT) cells exposed to myoglobin or lipopolysaccharide or submitted to metabolic reprogramming. Kidney function (BUN, glomerular filtration rate), expression of CCL7 receptors, and kidney infiltration by inflammatory cells (F4/80+ macrophages, MPO+ neutrophils, and B220+ B-cells) were assessed in wt and Ccl7-/- mice submitted to 3 different models of AKI or kidney fibrosis (uni/bilateral ischemia/reperfusion injury (u/bIRI) and rhabdomyolysis).

RESULTS

Toxin exposure of MCT cells, as well as metabolic reprogramming recapitulating AKI changes, led to a dramatic up-regulation of CCL7. In vivo, kidney expression of Ccl7 and Ccl2 significantly increased after AKI and remained increased beyond the acute phase (30 days after uIRI). The expression of the CCL7 receptors was heterogeneous and varied with time. Kidney function, expression of CCL7 receptors and Ccl2, and the number of inflammatory cells within kidneys were similar in wt and Ccl7-/- mice at baseline and at day 2 after AKI. 30 days after uIRI, kidney fibrosis was similar in both mouse strains.

CONCLUSIONS

Despite strong induction of CCL7 after AKI, CCL7 deficiency does not prevent AKI and the transition toward kidney fibrosis and should probably not be further explored as a potential target to prevent or treat AKI.

Teaching pharmacovigilance to French medical students during the COVID-19 pandemic: Interest of distance learning clinical reasoning sessions

BACKGROUND

Considering data from the literature in favor of active educational intervention to teach pharmacovigilance, we describe an innovative model of distance learning clinical reasoning sessions (CRS) of pharmacovigilance with 3rd year medical French students.

METHODS

The three main objectives were to identify the elements necessary for the diagnosis of an adverse drug reaction, report an adverse drug reaction and perform drug causality assessment. The training was organized in 3 stages. First, students practiced clinical reasoning (CRS) by conducting fictive pharmacovigilance telehealth consultations. Second, students wrote a medical letter summarizing the telehealth consultation and analyzing the drug causality assessment. This letter was sent to the teacher for a graded evaluation. In the third stage was a debriefing course with all the students.

RESULTS

Of the 293 third-year medical students enrolled in this course, 274 participated in the distance learning CRS. The evaluation received feedback from 195 students, with an average score of 8.85 out of 10. The qualitative evaluation had only positive feedback. The students appreciated the different format of the teaching, with the possibility to be active.

CONCLUSION

Through distance CRS of pharmacovigilance, medical students' competences to identify and report adverse drug reactions were tested. The students experienced the pharmacovigilance skills necessary to detect adverse drug reactions in a manner directly relevant to patient care. The overall evaluation of the students is in favor of this type of method.

Clinical decision-making training using the Script Concordance Test and simulation: A pilot study for pediatric residents

BACKGROUND

Each year, new pediatric residents begin their shifts in the pediatric emergency room. While technical skills are often acquired during workshops, non-technical skills such as communication, professionalism, situational awareness, or decision-making are rarely tested. Simulation enables non-technical skills to be developed in situations frequently encountered in pediatric emergencies. Adopting an innovative approach, we combined two pedagogical methods: the Script Concordance Test (SCT) and simulation to improve clinical reasoning and non-technical skills of first-year pediatric residents in dealing with clinical situations involving febrile seizures. The aim of this work is to report the feasibility of such a combined training.

METHODS

The first-year pediatric residents participated in a training session on how to manage a child attending the emergency department with a febrile seizure. At the beginning of the session, the trainees had to complete the SCT (seven clinical situations) and then participated in three simulation scenarios. Student satisfaction was assessed by means of a questionnaire at the end of the session.

RESULTS

In this pilot study, 20 residents participated in the training. The SCT scores for the first-year pediatric residents were lower and more widely distributed than those of the experts with better concordance for diagnostic items compared to investigation or treatment items. All were satisfied with the teaching methods employed. Further sessions on additional topics relating to the management of pediatric emergency cases were requested.

CONCLUSION

Although limited by the small size of our study, this combination of teaching methods was possible and seemed promising for the development of non-technical skills of pediatric residents. These methods are in line with the changes being made to the third cycle of medical studies in France and can be adapted to other situations and other specialties.

Machine Learning-Based Urine Peptidome Analysis to Predict and Understand Mechanisms of Progression to Kidney Failure

Introduction

The identification of patients with chronic kidney disease (CKD) at risk of progressing to kidney failure (KF) is important for clinical decision-making. In this study we assesed whether urinary peptidome (UP) analysis may help classify patients with CKD and improve KF risk prediction.

Methods

The UP was analyzed using capillary electrophoresis coupled to mass spectrometry in a case-cohort sample of 1000 patients with CKD stage G3 to G5 from the French CKD-Renal Epidemiology and Information Network (REIN) cohort. We used unsupervised and supervised machine learning to classify patients into homogenous UP clusters and to predict 3-year KF risk with UP, respectively. The predictive performance of UP was compared with the KF risk equation (KFRE), and evaluated in an external cohort of 326 patients.

Results

More than 1000 peptides classified patients into 3 clusters with different CKD severities and etiologies at baseline. Peptides with the highest discriminative power for clustering were fragments of proteins involved in inflammation and fibrosis, highlighting those derived from α-1-antitrypsin, a major acute phase protein with anti-inflammatory and antiapoptotic properties, as the most significant. We then identified a set of 90 urinary peptides that predicted KF with a c-index of 0.83 (95% confidence interval [CI]: 0.81-0.85) in the case-cohort and 0.89 (0.83-0.94) in the external cohort, which were close to that estimated with the KFRE (0.85 [0.83-0.87]). Combination of UP with KFRE variables did not further improve prediction.

Conclusion

This study shows the potential of UP analysis to uncover new pathophysiological CKD progression pathways and to predict KF risk with a performance equal to that of the KFRE.

Mapping of the amniotic fluid proteome of fetuses with congenital anomalies of the kidney and urinary tract identifies plastin 3 as a protein involved in glomerular integrity

Congenital anomalies of the kidney and the urinary tract (CAKUT) are the first cause of chronic kidney disease in childhood. Several genetic and environmental origins are associated with CAKUT, but most pathogenic pathways remain elusive. Considering the amniotic fluid (AF) composition as a proxy for fetal kidney development, we analyzed the AF proteome from non-severe CAKUT (n = 19), severe CAKUT (n = 14), and healthy control (n = 22) fetuses using LC-MS/MS. We identified 471 significant proteins that discriminated the three AF groups with 81% precision. Among them, eight proteins independent of gestational age (CSPG4, LMAN2, ENDOD1, ANGPTL2, PRSS8, NGFR, ROBO4, PLS3) were associated with both the presence and the severity of CAKUT. Among those, five were part of a protein-protein interaction network involving proteins previously identified as being potentially associated with CAKUT. The actin-bundling protein PLS3 (plastin 3) was the only protein displaying a gradually increased AF abundance from control, via non-severe, to severe CAKUT. Immunohistochemistry experiments showed that PLS3 was expressed in the human fetal as well as in both the fetal and the postnatal mouse kidney. In zebrafish embryos, depletion of PLS3 led to a general disruption of embryonic growth including reduced pronephros development. In postnatal Pls3-knockout mice, kidneys were macroscopically normal, but the glomerular ultrastructure showed thickening of the basement membrane and fusion of podocyte foot processes. These structural changes were associated with albuminuria and decreased expression of podocyte markers including Wilms' tumor-1 protein, nephrin, and podocalyxin. In conclusion, we provide the first map of the CAKUT AF proteome that will serve as a reference for future studies. Among the proteins strongly associated with CAKUT, PLS3 did surprisingly not specifically affect nephrogenesis but was found as a new contributor in the maintenance of normal kidney function, at least in part through the control of glomerular integrity. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Impact of menopausal status on kidney adaptation after unilateral nephrectomy for kidney donation in women

INTRODUCTION

Although living kidney donation is not a high-risk surgery, there is still a need to identify situations at risk of kidney disease after uninephrectomy. Estrogens exhibit a protective role against various nephropathies. The aim of this study was to assess renal adaptation following nephrectomy according to menopausal status in women.

METHODS

A prospective bicentric study including living women donors measured glomerular filtration rate (GFR) (inulin or ^51-Cr-EDTA clearances) and kidney volume (using CT-scan and 3-dimensional reconstruction), before and after 1-year post-uninephrectomy. Renal adaptation was compared according to menopausal status.

RESULTS

Sixteen non-menopausal women and 18 menopausal women were included. One year following uninephrectomy, the mean decrease in GFR (global population) was - 32 ± 12 ml/min/1.73 m², and the mean increase in remnant kidney volume was + 32 ± 13 cm³/1.73 m². No significant difference was observed between the two groups for both the decrease in GFR (-32.9 ± 13.3 in non-menopausal vs - 31.5 ± 9.9 in menopausal, ml/min/1.73 m², p = 0.84), and the increase in kidney volume (+ 36.1 ± 13.4 in non-menopausal vs + 28.1 ± 12.5 in menopausal, cm³/1.73 m², p = 0.09).

DISCUSSION

Menopausal status did not influence kidney adaptation following uninephrectomy, and in this respect is not a potential limiting factor for living kidney donation.

Urine osmolality predicts calcium-oxalate crystallization risk in patients with recurrent urolithiasis

Our aim was to investigate the validity of osmolality from 24-h urine collection in examining the risk for calcium-oxalate (CaOx) kidney stone formation in patients with recurrent urolithiasis. Three hundred and twelve subjects (males/females: 184/128) from France with a history of recurrent kidney stones from confirmed or putative CaOx origin were retrospectively included in the study (46 ± 14 years, BMI: 25.3 ± 5.0 kg·m^-2). Tiselius' crystallization risk index (CRI) was calculated based on urinary calcium, oxalate, citrate, magnesium, and volume from 24-h samples. The diagnostic ability of 24-h urine osmolality to classify patients as high risk for kidney stone crystallization was examined through the receivers operating characteristics analysis. High risk for CaOx crystallization was defined as CRI > 1.61 and > 1.18, for males and females, respectively. The accuracy of urine osmolality to diagnose risk of CaOx stone formation (AUC, area under the curve) for females was 84.6%, with cut-off point of 501 mmol·kg^-1 (sensitivity: 83.3%, specificity: 76.0%). Males had AUC of 85.8% with threshold of 577 mmo·kg^-1 (sensitivity: 85.5%, specificity: 77.6%). A negative association was found between 24-h urine volume and osmolality (r = - 0.63, P < 0.001). Also, a positive association was found between 24-h urine osmolality and CRI (r = 0.65, P < 0.001), as well as urea excretion with CRI (r = 0.37, P < 0.001). In conclusion, urine osmolality > 501 and > 577 mmol·kg^-1, in female and in male, respectively, was associated with a risk for CaOx kidney stone formation in patients with a history of recurrent urolithiasis. Thus, when CaOx origin is confirmed or suspected, 24-h urine osmolality provides a simple way to define individualized target of urine dilution to prevent urine crystallization and stone formation.

Mutation affecting the conserved acidic WNK1 motif causes inherited hyperkalemic hyperchloremic acidosis

Gain-of-function mutations in with no lysine (K) 1 (WNK1) and WNK4 genes are responsible for familial hyperkalemic hypertension (FHHt), a rare, inherited disorder characterized by arterial hypertension and hyperkalemia with metabolic acidosis. More recently, FHHt-causing mutations in the Kelch-like 3-Cullin 3 (KLHL3-CUL3) E3 ubiquitin ligase complex have shed light on the importance of WNK's cellular degradation on renal ion transport. Using full exome sequencing for a 4-generation family and then targeted sequencing in other suspected cases, we have identified new missense variants in the WNK1 gene clustering in the short conserved acidic motif known to interact with the KLHL3-CUL3 ubiquitin complex. Affected subjects had an early onset of a hyperkalemic hyperchloremic phenotype, but normal blood pressure values"Functional experiments in Xenopus laevis oocytes and HEK293T cells demonstrated that these mutations strongly decrease the ubiquitination of the kidney-specific isoform KS-WNK1 by the KLHL3-CUL3 complex rather than the long ubiquitous catalytically active L-WNK1 isoform. A corresponding CRISPR/Cas9 engineered mouse model recapitulated both the clinical and biological phenotypes. Renal investigations showed increased activation of the Ste20 proline alanine-rich kinase-Na+-Cl- cotransporter (SPAK-NCC) phosphorylation cascade, associated with impaired ROMK apical expression in the distal part of the renal tubule. Together, these new WNK1 genetic variants highlight the importance of the KS-WNK1 isoform abundance on potassium homeostasis.

Clinical characteristics of familial hypocalciuric hypercalcaemia type 1: A multicentre study of 77 adult patients

OBJECTIVE

Familial hypocalciuric hypercalcaemia type 1 (FHH1), related to heterozygous loss-of-function mutations of the calcium-sensing receptor gene, is the main differential diagnosis for primary hyperparathyroidism. The aim of our study was to describe clinical characteristics of adult patients living in France with a genetically confirmed FHH1.

DESIGN AND PATIENTS

This observational, retrospective, multicentre study included 77 adults, followed up in 32 clinical departments in France, with a genetic FHH1 diagnosis between 2001 and 2012.

RESULTS

Hypercalcaemia was diagnosed at a median age of 53 years [IQR: 38-61]. The diagnosis was made after clinical manifestations, routine analysis or familial screening in 56, 34 and 10% of cases, respectively, (n = 58; data not available for 19 patients). Chondrocalcinosis was present in 11/51 patients (22%), bone fractures in 8/56 (14%) and renal colic in 6/55 (11%). The median serum calcium was 2.74 mmol/L [IQR: 2.63-2.86 mmol/L], the median plasma parathyroid hormone level was 4.9 pmol/L [3.1-7.1], and the median 24-hour urinary calcium excretion was 2.8 mmol/24 hours [IQR: 1.9-4.0]. Osteoporosis (dual X-ray absorptiometry) or kidney stones (renal ultrasonography) were found in 6/38 patients (16%) and 9/32 patients (28%), respectively. Fourteen patients (18%) underwent parathyroid surgery; parathyroid adenoma was found in three patients (21%) and parathyroid hyperplasia in nine patients (64%). No correlation between genotype and phenotype was established.

CONCLUSION

This large cohort study demonstrates that FHH1 clinical characteristics can be atypical in 33 patients (43%). Clinicians should be aware of this rare differential diagnosis in order to adopt an appropriate treatment strategy.

Hydration for health hypothesis: a narrative review of supporting evidence

PURPOSE

An increasing body of evidence suggests that excreting a generous volume of diluted urine is associated with short- and long-term beneficial health effects, especially for kidney and metabolic function. However, water intake and hydration remain under-investigated and optimal hydration is poorly and inconsistently defined. This review tests the hypothesis that optimal chronic water intake positively impacts various aspects of health and proposes an evidence-based definition of optimal hydration.

METHODS

Search strategy included PubMed and Google Scholar using relevant keywords for each health outcome, complemented by manual search of article reference lists and the expertise of relevant practitioners for each area studied.

RESULTS

The available literature suggest the effects of increased water intake on health may be direct, due to increased urine flow or urine dilution, or indirect, mediated by a reduction in osmotically -stimulated vasopressin (AVP). Urine flow affects the formation of kidney stones and recurrence of urinary tract infection, while increased circulating AVP is implicated in metabolic disease, chronic kidney disease, and autosomal dominant polycystic kidney disease.

CONCLUSION

In order to ensure optimal hydration, it is proposed that optimal total water intake should approach 2.5 to 3.5 L day^-1 to allow for the daily excretion of 2 to 3 L of dilute (< 500 mOsm kg^-1) urine. Simple urinary markers of hydration such as urine color or void frequency may be used to monitor and adjust intake.

Kinin B1 receptor: a potential therapeutic target in sepsis-induced vascular hyperpermeability

Background

In sepsis, the endothelial barrier becomes incompetent, with the leaking of plasma into interstitial tissues. VE-cadherin, an adherens junction protein, is the gatekeeper of endothelial cohesion. Kinins, released during sepsis, induce vascular leakage and vasodilation. They act via two G-protein coupled receptors: B1 (B1R) and B2 (B2R). B1R is inducible in the presence of pro-inflammatory cytokines, endotoxins or after tissue injury. It acts at a later stage of sepsis and elicits a sustained inflammatory response. The aim of our study was to investigate the relationships between B1R and VE-cadherin destabilization in vivo in a later phase of sepsis.

Methods

Experimental, prospective study in a university research laboratory. We used a polymicrobial model of septic shock by cecal ligation and puncture in C57BL6 male mice or C57BL6 male mice that received a specific B1R antagonist (R-954). We studied the influence of B1R on sepsis-induced vascular permeability 30 h after surgery for several organs, and VE-cadherin expression in the lung and kidneys by injecting R-954 just before surgery. The 96-h survival was determined in mice without treatment or in animals receiving R-954 as a “prophylactic” regimen (a subcutaneous injection of 200 µg/kg, prior to CLP and 24 h after CLP), or as a “curative” regimen (injection of 100 µg/kg at H6, H24 and H48 post-surgery).

Results

B1R inactivation helps to maintain MAP above 65 mmHg but induces different permeability profiles depending on whether or not organ perfusion is autoregulated. In our model, VE-cadherin was destabilized in vivo during septic shock. At a late stage of sepsis, the B1R blockade reduced the VE-cadherin disruption by limiting eNOS activation. The survival rate for mice that received R-954 after sepsis induction was higher than in animals that received an antagonist as a prophylactic treatment.

Conclusions

B1R antagonizing reduced mortality in our model of murine septic shock by limiting the vascular permeability induced by VE-cadherin destabilization through maintenance of the macrohemodynamics, consequently limiting organ dysfunctions.

Tibial post fracture pain is reduced in kinin receptors deficient mice and blunted by kinin receptor antagonists

BACKGROUND

Tibial fracture is associated with inflammatory reaction leading to severe pain syndrome. Bradykinin receptor activation is involved in inflammatory reactions, but has never been investigated in fracture pain.

METHODS

This study aims at defining the role of B1 and B2-kinin receptors (B1R and B2R) in a closed tibial fracture pain model by using knockout mice for B1R (B1KO) or B2R (B2KO) and wild-type (WT) mice treated with antagonists for B1R (SSR 240612 and R954) and B2R (HOE140) or vehicle. A cyclooxygenase (COX) inhibitor (ketoprofen) and an antagonist (SB366791) of Transient Receptor Potential Vaniloid1 (TRPV1) were also investigated since these pathways are associated with BK-induced pain in other models. The impact on mechanical and thermal hyperalgesia and locomotion was assessed by behavior tests. Gene expression of B1R and B2R and spinal cord expression of c-Fos were measured by RT-PCR and immunohistochemistry, respectively.

RESULTS

B1KO and B2KO mice demonstrated a reduction in post-fracture pain sensitivity compared to WT mice that was associated with decreased c-Fos expression in the ipsilateral spinal dorsal horn in B2KO. B1R and B2R mRNA and protein levels were markedly enhanced at the fracture site. B1R and B2R antagonists and inhibition of COX and TRPV1 pathways reduced pain in WT. However, the analgesic effect of the COX-1/COX-2 inhibitor disappeared in B1KO and B2KO. In contrast, the analgesic effect of the TRPV1 antagonist persisted after gene deletion of either receptor.

CONCLUSIONS

It is suggested that B1R and B2R activation contributes significantly to tibial fracture pain through COX. Hence, B1R and B2R antagonists appear potential therapeutic agents to manage post fracture pain.

Resistance to Insulin in Patients with Gitelman Syndrome and a Subtle Intermediate Phenotype in Heterozygous Carriers: A Cross-Sectional Study

BACKGROUND

Gitelman syndrome is a salt-losing tubulopathy caused by mutations in the SLC12A3 gene, which encodes the thiazide-sensitive sodium-chloride cotransporter. Previous studies suggested an intermediate phenotype for heterozygous carriers.

METHODS

To evaluate the phenotype of heterozygous carriers of pathogenic SLC12A3 mutations, we performed a cross-sectional study of patients with Gitelman syndrome, heterozygous carriers, and healthy noncarriers. Participants measured their BP at home for three consecutive days before hospital admission for blood and urine sampling and an oral glucose tolerance test.

RESULTS

We enrolled 242 participants, aged 18-75 years, including 81 heterozygous carriers, 82 healthy noncarriers, and 79 patients with Gitelman syndrome. The three groups had similar age, sex ratio, and body mass index. Compared with healthy noncarriers, heterozygous carriers showed significantly higher serum calcium concentration (P=0.01) and a trend for higher plasma aldosterone (P=0.06), but measures of home BP, plasma and urine electrolytes, renin, parathyroid hormone, vitamin D, and response to oral glucose tolerance testing were similar. Patients with Gitelman syndrome had lower systolic BP and higher heart rate than noncarriers and heterozygote carriers; they also had significantly higher fasting serum glucose concentration, higher levels of markers of insulin resistance, and a three-fold higher sensitivity to overweight. According to oral glucose tolerance testing, approximately 14% of patients with Gitelman syndrome were prediabetic, compared with 5% of heterozygous carriers and 4% of healthy noncarriers.

CONCLUSIONS

Heterozygous carriers had a weak intermediate phenotype, between that of healthy noncarriers and patients with Gitelman syndrome. Moreover, the latter are at risk for development of type 2 diabetes, indicating the heightened importance of body weight control in these patients.

Effect of Increased Daily Water Intake in Premenopausal Women With Recurrent Urinary Tract Infections: A Randomized Clinical Trial

IMPORTANCE

Increased hydration is often recommended as a preventive measure for women with recurrent cystitis, but supportive data are sparse.

OBJECTIVE

To assess the efficacy of increased daily water intake on the frequency of recurrent cystitis in premenopausal women.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, open-label, controlled, 12-month trial at a clinical research center (years 2013-2016). Among 163 healthy women with recurrent cystitis (≥3 episodes in past year) drinking less than 1.5 L of fluid daily assessed for eligibility, 23 were excluded and 140 assigned to water or control group. Assessments of daily fluid intake, urinary hydration, and cystitis symptoms were performed at baseline, 6- and 12-month visits, and monthly telephone calls.

INTERVENTIONS

Participants were randomly assigned to drink, in addition to their usual fluid intake, 1.5 L of water daily (water group) or no additional fluids (control group) for 12 months.

MAIN OUTCOMES AND MEASURES

Primary outcome measure was frequency of recurrent cystitis over 12 months. Secondary outcomes were number of antimicrobial regimens used, mean time interval between cystitis episodes, and 24-hour urinary hydration measurements.

RESULTS

The mean (SD) age of the 140 participants was 35.7 (8.4) years, and the mean (SD) number of cystitis episodes in the previous year was 3.3 (0.6). During the 12-month study period, the mean (SD) number of cystitis episodes was 1.7 (95% CI, 1.5-1.8) in the water group compared with 3.2 (95% CI, 3.0-3.4) in the control group, with a difference in means of 1.5 (95% CI, 1.2-1.8; P < .001). Overall, there were 327 cystitis episodes, 111 in the water group and 216 in the control group. The mean number of antimicrobial regimens used to treat cystitis episodes was 1.9 (95% CI, 1.7-2.2) and 3.6 (95% CI, 3.3-4.0), respectively, with a difference in means of 1.7 (95% CI, 1.3-2.1; P < .001). The mean time interval between cystitis episodes was 142.8 (95% CI, 127.4-160.1) and 84.4 (95% CI, 75.4-94.5) days, respectively, with a difference in means of 58.4 (95% CI, 39.4-77.4; P < .001). Between baseline and 12 months, participants in the water group, compared with those in the control group, had increased mean (SD) urine volume (1.4 [0.04] vs 0.1 [0.04] L; P < .001) and voids (2.4 [0.2] vs -0.1 [0.2]; P < .001) and decreased urine osmolality (-402.8 [19.6] vs -24.0 [19.5] mOsm/kg; P < .001).

CONCLUSIONS AND RELEVANCE

Increased water intake is an effective antimicrobial-sparing strategy to prevent recurrent cystitis in premenopausal women at high risk for recurrence who drink low volumes of fluid daily.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02444975.

Syndrome of inappropriate anti-diuresis induces volume-dependent hypercalciuria

Hyponatremia is associated with bone demineralization. We hypothesized that, during hyponatremia, calciuria and calcium balance depend on volemic status. We evaluated calciuria in patients with hyponatremia, secondary to SIAD or hypovolemia. Patients with SIAD exhibited a volemic expansion that was associated with hypercalciuria. Calciuria was proportional to markers of volemia.

INTRODUCTION

Chronic mild hyponatremia has been associated with bone demineralization of unknown mechanisms. During chronic hyponatremia, arginine-vasopressin secretion can result from hypovolemia or from syndrome of inappropriate anti-diuresis (SIAD) that leads to a slightly volemic expansion. Since volemia determines renal calcium excretion and balance, we evaluated calcium homeostasis in patients with chronic hyponatremia, related to SIAD or to hypovolemia.

METHODS

We retrospectively included all patients referred to our Department between May 2006 and May 2014 for hyponatremia, resulting from SIAD or chronic hypovolemia. None had edema, cirrhosis, cardiac, or renal insufficiency. Exploration included estimation of volemia, extracellular fluid volume (ECFV) measurement with inulin, and calcium homeostasis.

RESULTS

In total, the SIAD and hypovolemic groups included 22 and 7 patients, respectively. The SIAD group exhibited signs of increased volemia: higher glomerular filtration rate, higher fractional excretion of uric acid, and lower plasma renin. ECFV exceeded that of the hypovolemic group and was above usual values. There was no difference between the two groups regarding plasma calcium, PTH, and vitamin D. However, in the SIAD group, calciuria was higher than in the hypovolemic group, reaching levels of hypercalciuria. Furthermore, there was a positive correlation between calciuria and markers of volemia.

CONCLUSIONS

Our results show that SIAD results in a volemic expansion tendency that is associated with a decrease in renal calcium reabsorption and thus hypercalciuria, whereas in the hypovolemic group, calciuria was not increased. Therefore, renal loss of calcium and bone demineralization in SIAD patients could be partly induced by volemic expansion.

Prevention of Recurrent Acute Uncomplicated Cystitis by Increasing Daily Water in Premenopausal Women: A Prospective, Randomized, Controlled Study

Background

Increased hydration is commonly recommended as a preventive measure for women with recurrent acute uncomplicated cystitis (rAUC), but supportive data are sparse. The aim of this study was to assess the efficacy of increased daily water intake on the frequency of rAUC in premenopausal women.

Methods

140 healthy premenopausal asymptomatic women drinking less than 1.5 L of total fluid daily (24 hours) and suffering from rAUC (³3 episodes in the past year) were randomized to receive, in addition to their usual daily fluid intake, either 1.5 L water daily (water group) or no additional fluids (control group), for 12 months. Assessments of daily water and total fluid intake, urine volume and osmolality, number of urine voids, and occurrence of AUC symptoms and a reminder to notify investigators of any such symptoms were performed at baseline, 6- and 12-month clinic visits in addition to monthly telephone calls. The primary outcome was frequency of rAUC episodes (³1 AUC symptom and ³10³ CFU/mL of a uropathogen in voided urine) over 12 months.

Results

Between baseline and 12 month’s follow-up, the water group, compared with the control group, had statistically significant increases in mean daily water intake (1.15 vs. −0.01 L), total fluid intake (1.65 vs. 0.03 L), urine volume (1.40 vs. 0.04 L), and number of urine voids (2.2 vs. −0.2), and a decrease in urine osmolality (−408 vs. −35 mOsm/Kg). The mean number of rAUC episodes in the water group was significantly less than in the control group (1.6 vs. 3.1; odds ratio 0.52, 95% CI 0.46–0.60, 
P < 0.0001) (figure shows cumulative sum of AUC episodes over 12 months in both study groups). The mean number of antimicrobial regimens used to treat AUC events was 1.8 in the water group vs. 3.5 in the control group (P < 0.0001). In addition, the mean number of days to first rAUC and the mean number of days between rAUC episodes was longer in the water group compared with the control group (148 vs. 93,
 P = 0.0005 and 143 vs. 85, P < 0.0001, respectively).

Conclusions

Our results provide strong evidence that increased water intake is an effective antimicrobial-sparing preventive strategy for women with rAUC. Increasing daily water intake by approximately 1.5 L reduced rAUC episodes by 48% and antimicrobial regimens by 47% over 12 months.

Disclosures

M. Vecchio, Danone Research: Employee, Salary. A. Iroz, Dzanone Research: Employee, Salary. I. Tack, Danone Research: Consultant, Consulting fee and Speaker honorarium. Q. Dornic, Danone research: Employee, Salary. I. Seksek, Danone Research: Employee, Salary.

Sepsis modeling in mice: ligation length is a major severity factor in cecal ligation and puncture

Background

The cecal ligation and puncture (CLP) model, a gold standard in sepsis research, is associated with an important variability in mortality. While the number of punctures and needle size is well described in CLP animal studies, the length of cecal ligation is often not. The relationship between cecal ligation and survival in mice is briefly reported in the literature; therefore, we devised an investigation in mice of the consequences of three standardized cecal ligation lengths on mortality and the severity of the ensued sepsis.

Methods

Male C57BL/6J mice underwent standardized CLP. The cecum was ligated at 5, 20, or 100 % of its total length and further perforated by a single 20-G puncture. Mortality was analyzed. We assessed blood lactate, serum creatinine levels, and serum cytokines (TNF-α, IL-1β, IL-6, and IL-10) after procedure in a control group and in ligated mice.

Results

Mortality was directly related to ligation length: median survival was 24 h for the “100 %” group and 44 h for the “20 %” group. Blood lactate increased proportionally with the ligation length. At 6 h post-procedure, pro-inflammatory cytokines significantly increased in the ligated group with significantly higher serum levels of IL-6 in the 100 % group compared to the other ligated groups. The 20 % group exhibited the characteristics of septic shock with hypotension below 65 mmHg, pro-inflammatory balance, organ dysfunction, and hyperlactatemia.

Conclusions

Cecal ligation length appears to be a major limiting factor in the mouse CLP model. Thus, this experimental model should be performed with high consistency in future protocol designs.

Familial Hypocalciuric Hypercalcemia Types 1 and 3 and Primary Hyperparathyroidism: Similarities and Differences

CONTEXT

Familial hypocalciuric hypercalcemia (FHH) is a genetically heterogeneous condition resembling primary hyperparathyroidism (PHPT) but not curable by surgery; FHH types 1, 2, and 3 are due to loss-of-function mutations of the CASR, GNA11, or AP2S1 genes, respectively.

OBJECTIVE

This study aimed to compare the phenotypes of patients with genetically proven FHH types 1 or 3 or PHPT.

DESIGN, SETTING, AND PATIENTS

This was a mutation analysis in a large cohort, a cross-sectional comparison of 52 patients with FHH type 1, 22 patients with FHH type 3, 60 with PHPT, and 24 normal adults.

INTERVENTION

There were no interventions.

MAIN OUTCOME MEASURES

Abnormalities of the CASR, GNA11, and AP2S1 genes, blood calcium, phosphate, and PTH concentrations, urinary calcium excretion were measured.

RESULTS

In 133 families, we detected 101 mutations in the CASR gene, 68 of which were previously unknown, and in 19 families, the three recurrent AP2S1 mutations. No mutation was detected in the GNA11 gene. Patients with FHH type 3 had higher plasma calcium concentrations than patients with FHH type 1, despite having similar PTH concentrations and urinary calcium excretion. Renal tubular calcium reabsorption levels were higher in patients with FHH type 3 than in those with FHH type 1. Plasma calcium concentration was higher whereas PTH concentration and urinary calcium excretion were lower in FHH patients than in PHPT patients. In patients with FHH or PHPT, all data groups partially overlapped.

CONCLUSION

In our population, AP2S1 mutations affect calcium homeostasis more severely than CASR mutations. Due to overlap, the risk of confusion between FHH and PHPT is high.

Beneficial effects of levobupivacaine regional anaesthesia on postoperative opioid induced hyperalgesia in diabetic mice

Background

Diabetic neuropathy is one of the most common complications of diabetes and causes various problems in daily life. The aim of this study was to assess the effect of regional anaesthesia on post surgery opioid induced hyperalgesia in diabetic and non-diabetic mice.

Methods

Diabetic and non-diabetic mice underwent plantar surgery. Levobupivacaine and sufentanil were used before surgery, for sciatic nerve block (regional anaesthesia) and analgesia, respectively. Diabetic and non-diabetic groups were each randomly assigned to three subgroups: control, no sufentanil and no levobupivacaine; sufentanil and no levobupivacaine; sufentanil and levobupivacaine. Three tests were used to assess pain behaviour: mechanical nociception; thermal nociception and guarding behaviours using a pain scale.

Results

Sufentanil, alone or in combination with levobupivacaine, produced antinociceptive effects shortly after administration. Subsequently, sufentanil induced hyperalgesia in diabetic and non-diabetic mice. Opioid-induced hyperalgesia was enhanced in diabetic mice. Levobupivacaine associated to sufentanil completely prevented hyperalgesia in both groups of mice.

Conclusion

The results suggest that regional anaesthesia can decrease opioid-induced hyperalgesia in diabetic as well as in non-diabetic mice. These observations may be clinically relevant for the management of diabetic patients.

[Urinary tract infections: Economical impact of water intake]

BACKGROUNDS

This study aims to estimate the impact of preventing urinary tract infections (UTI), using a strategy of increased water intake, from the payer's perspective in the French health care system.

METHODS

A Markov model enables a comparison of health care costs and outcomes for a virtual cohort of subjects with different levels of daily water intake. The analysis of the budgetary impact was based on a period of 5years. The analysis was based on a 25-year follow-up period to assess the effects of adequate water supply on long-term complications.

RESULTS

The authors estimate annual primary incidence of UTI and annual risk of recurrence at 5.3% and 30%, respectively. Risk reduction associated with greater water intake reached 45% and 33% for the general and recurrent populations, respectively. The average total health care cost of a single UTI episode is €1074; for a population of 65 millions, UTI management represents a cost of €3.700 millions for payers. With adequate water intake, the model indicates a potential cost savings of €2.288 millions annually, by preventing 27 million UTI episodes. At the individual level, the potential cost savings is approximately €2915.

CONCLUSIONS

Preventing urinary tract infections using a strategy of adequate water intake could lead to significant cost savings for a public health care system. Further studies are needed to assess the effectiveness of such an approach.

Indomethacin, amiloride, or eplerenone for treating hypokalemia in Gitelman syndrome

Patients with Gitelman syndrome (GS), an inherited salt-losing tubulopathy, are usually treated with potassium-sparing diuretics or nonsteroidal anti-inflammatory drugs and oral potassium and magnesium supplementations. However, evidence supporting these treatment options is limited to case series studies. We designed an open-label, randomized, crossover study with blind end point evaluation to compare the efficacy and safety of 6-week treatments with one time daily 75 mg slow-release indomethacin, 150 mg eplerenone, or 20 mg amiloride added to constant potassium and magnesium supplementation in 30 patients with GS (individual participation: 48 weeks). Baseline plasma potassium concentration was 2.8±0.4 mmol/L and increased by 0.38 mmol/L (95% confidence interval [95% CI], 0.23 to 0.53; P<0.001) with indomethacin, 0.15 mmol/L (95% CI, 0.02 to 0.29; P=0.03) with eplerenone, and 0.19 mmol/L (95% CI, 0.05 to 0.33; P<0.01) with amiloride. Fifteen patients became normokalemic: six with indomethacin, three with eplerenone, and six with amiloride. Indomethacin significantly reduced eGFR and plasma renin concentration. Eplerenone and amiloride each increased plasma aldosterone by 3-fold and renin concentration slightly but did not significantly change eGFR. BP did not significantly change. Eight patients discontinued treatment early because of gastrointestinal intolerance to indomethacin (six patients) and hypotension with eplerenone (two patients). In conclusion, each drug increases plasma potassium concentration in patients with GS. Indomethacin was the most effective but can cause gastrointestinal intolerance and decreased eGFR. Amiloride and eplerenone have similar but lower efficacies and increase sodium depletion. The benefit/risk ratio of each drug should be carefully evaluated for each patient.

Long term metabolic syndrome induced by a high fat high fructose diet leads to minimal renal injury in C57BL/6 mice

Metabolic syndrome can induce chronic kidney disease in humans. Genetically engineered mice on a C57BL/6 background are highly used for mechanistic studies. Although it has been shown that metabolic syndrome induces cardiovascular lesions in C57BL/6 mice, in depth renal phenotyping has never been performed. Therefore in this study we characterized renal function and injury in C57BL/6 mice with long-term metabolic syndrome induced by a high fat and fructose diet (HFFD). C57BL/6 mice received an 8 months HFFD diet enriched with fat (45% energy from fat) and drinking water enriched with fructose (30%). Body weight, food/water consumption, energy intake, fat/lean mass ratio, plasma glucose, HDL, LDL, triglycerides and cholesterol levels were monitored. At 3, 6 and 8 months, renal function was determined by inulin clearance and measure of albuminuria. At sacrifice, kidneys and liver were collected. Metabolic syndrome in C57BL/6 mice fed a HFFD was observed as early 4 weeks with development of type 2 diabetes at 8 weeks after initiation of diet. However, detailed analysis of kidney structure and function showed only minimal renal injury after 8 months of HFFD. HFFD induced moderate glomerular hyperfiltration (436,4 µL/min vs 289,8 µL/min; p-value=0.0418) together with a 2-fold increase in albuminuria only after 8 months of HFFD. This was accompanied by a 2-fold increase in renal inflammation (p-value=0.0217) but without renal fibrosis or mesangial matrix expansion. In addition, electron microscopy did not show alterations in glomeruli such as basal membrane thickening and foot process effacement. Finally, comparison of the urinary peptidome of these mice with the urinary peptidome from humans with diabetic nephropathy also suggested absence of diabetic nephropathy in this model. This study provides evidence that the HFFD C57BL/6 model is not the optimal model to study the effects of metabolic syndrome on the development of diabetic kidney disease.

Relation between urinary hydration biomarkers and total fluid intake in healthy adults

BACKGROUND/OBJECTIVES

In sedentary adults, hydration is mostly influenced by total fluid intake and not by sweat losses; moreover, low daily fluid intake is associated with adverse health outcomes. This study aimed to model the relation between total fluid intake and urinary hydration biomarkers.

SUBJECTS/METHODS

During 4 consecutive weekdays, 82 adults (age, 31.6±4.3 years; body mass index, 23.2±2.7 kg/m(2); 52% female) recorded food and fluid consumed, collected one first morning urine (FMU) void and three 24-h (24hU) samples. The strength of linear association between urinary hydration biomarkers and fluid intake volume was evaluated using simple linear regression and Pearson's correlation. Multivariate partial least squares (PLS) modeled the association between fluid intake and 24hU hydration biomarkers.

RESULTS

Strong associations (|r| &#8805; 0.6; P<0.001) were found between total fluid intake volume and 24hU osmolality, color, specific gravity (USG), volume and solute concentrations. Many 24hU biomarkers were collinear (osmolality versus color: r=0.49-0.76; USG versus color: r=0.46-0.78; osmolality versus USG: 0.86-0.97; P<0.001). Measures in FMU were not strongly correlated to intake. Multivariate PLS and simple linear regression using urine volume explained >50% of the variance in fluid intake volume (r(2)=0.59 and 0.52, respectively); however the error in both models was high and the limits of agreement very large.

CONCLUSIONS

Hydration biomarkers in 24hU are strongly correlated with daily total fluid intake volume in sedentary adults in free-living conditions; however, the margin of error in the present models limits the applicability of estimating fluid intake from urinary biomarkers.

Hnf-1β transcription factor is an early hif-1α-independent marker of epithelial hypoxia and controls renal repair

Epithelial repair following acute kidney injury (AKI) requires epithelial-mesenchyme-epithelial cycling associated with transient re-expression of genes normally expressed during kidney development as well as activation of growth factors and cytokine-induced signaling. In normal kidney, the Hnf-1β transcription factor drives nephrogenesis, tubulogenesis and epithelial homeostasis through the regulation of epithelial planar cell polarity and expression of developmental or tubular segment-specific genes. In a mouse model of ischemic AKI induced by a 2-hours hemorrhagic shock, we show that expression of this factor is tightly regulated in the early phase of renal repair with a biphasic expression profile (early down-regulation followed by transient over-expression). These changes are associated to tubular epithelial differentiation as assessed by KSP-cadherin and megalin-cubilin endocytic complex expression analysis. In addition, early decrease in Hnf1b expression is associated with the transient over-expression of one of its main target genes, the suppressor of cytokine signaling Socs3, which has been shown essential for renal repair. In vitro, hypoxia induced early up-regulation of Hnf-1β from 1 to 24 hours, independently of the hypoxia-inducible factor Hif-1α. When prolonged, hypoxia induced Hnf-1β down-regulation while normoxia led to Hnf-1β normalization. Last, Hnf-1β down-regulation using RNA interference in HK-2 cells led to phenotype switch from an epithelial to a mesenchyme state. Taken together, we showed that Hnf-1β may drive recovery from ischemic AKI by regulating both the expression of genes important for homeostasis control during organ repair and the state of epithelial cell differentiation.

Renal functional decline and glomerulotubular injury are arrested but not restored by release of unilateral ureteral obstruction (UUO)

Murine unilateral ureteral obstruction (UUO), a major model of progressive kidney disease, causes loss of proximal tubular mass and formation of atubular glomeruli. Adult C57BL/6 mice underwent a sham operation or reversible UUO under anesthesia. In group 1, kidneys were harvested after 7 days. In group 2, the obstruction was released after 7 days, and a physiological study of both kidneys was performed 30 days later. Renal blood flow (RBF), glomerular filtration rate (GFR), urine protein, and albumin excretion were measured after ligation of either the left or right ureter. Glomerular volume (periodic acid-Schiff), glomerulotubular integrity and proximal tubular mass (Lotus tetragonolobus lectin), and interstitial collagen (Sirius red) were measured by histomorphometry. Obstructed kidney weight was reduced by 15% at 7 days but was not different from sham after a 30-day recovery. Glomerular volume and proximal tubular area of the obstructed kidney were reduced by 55% at 7 days, but normalized after 30 days. Interstitial collagen deposition increased 2.4-fold after 7 days of UUO and normalized after release. However, GFR and RBF were reduced by 40% and urine albumin/protein ratio was increased 2.8-fold 30 days after release of UUO. This was associated with a 50% reduction in glomerulotubular integrity despite a 30-day recovery (P < 0.05 for all data). We conclude that release of 7-day UUO can arrest progression but does not restore normal function of the postobstructed kidney. Although the remaining intact nephrons have hypertrophied, glomerular injury is revealed by albuminuria. These results suggest that glomerulotubular injury should become the primary target of slowing progressive kidney disease.

GFR estimation using standardized cystatin C in kidney transplant recipients

BACKGROUND

The utility of serum cystatin C (SCysC) as a filtration marker in kidney transplantation is uncertain. We took advantage of the recent validation of a reference calibrator for SCysC and of newly developed CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations (2012) expressed for use with standardized SCysC level to reassess the performance of SCysC as a filtration marker in kidney transplant recipients.

STUDY DESIGN

Study of diagnostic test accuracy.

SETTING & PARTICIPANTS

670 kidney transplant recipients from 3 centers undergoing glomerular filtration rate (GFR) measurements from December 2006 to November 2012.

INDEX TEST

Estimated GFR (eGFR) using the 2012 SCysC-based and serum creatinine (SCr)/SCysC-based CKD-EPI equations (eGFR(cys) and eGFR(cr-cys), respectively) and the 2009 SCr-based CKD-EPI equation (eGFR(cr)), with SCysC and SCr measured at a single laboratory between April 2011 and June 2011.

REFERENCE TEST

Measured GFR (mGFR) using urinary clearance of inulin.

RESULTS

Bias (the difference between mGFR and eGFR) was significantly smaller for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (-2.82 and -0.54 vs +4.4 mL/min/1.73 m(2), respectively; P < 0.001). Precision (standard deviation of the mean bias) also was better for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (12 and 11 vs 13 mL/min/1.73 m(2) [P < 0.001 for both comparisons]). Accuracy (percentage of GFR estimates within 30% of mGFR) was greater for eGFR(cys) and eGFR(cr-cys) versus eGFR(cr) (81% and 86% vs 75%, respectively [P = 0.004 and P < 0.001]). Net reclassification index with respect to mGFR of 30 mL/min/1.73 m(2) for eGFR(cr-cys) and eGFR(cys) versus eGFR(cr) was 18.8% [95% CI, 8.6%-28.9%] and 22.5% [95% CI, 10.2%-34.9%].

LIMITATIONS

Patients were exclusively of European descent; association with transplant outcome was not evaluated.

CONCLUSIONS

Our data validate the use of both the newly developed SCysC-based and SCr/SCysC-based CKD-EPI equations (2012) in kidney transplant recipients. Both equations perform better than the SCr-based CKD-EPI equation (2009).

Increased water intake as a prevention strategy for recurrent urolithiasis: major impact of compliance on cost-effectiveness

PURPOSE

We evaluated the economic impact of preventing recurrent stones using a strategy of increased water intake and determined the impact of compliance on cost-effectiveness for the French health care system.

MATERIALS AND METHODS

A Markov model was constructed to compare costs and outcomes for recurrent kidney stone formers with less than 2 L vs 2 L or more daily fluid intake. Model assumptions included an annual prevalence of 120,000 stone episodes in France, 14.4% annual risk of stone recurrence and a 55% risk reduction in subjects with adequate water intake. Costs were based on resource use as estimated by a panel of experts and official national price lists. Outcomes were from the perspective of the public health payer, and encompassed direct and indirect costs.

RESULTS

The total cost of an episode of urolithiasis was estimated at €4,267 including the cost of treatment and complications. This corresponds to an annual budget impact of €88 million for recurrent stones based on 21,000 stone events. Assuming 100% compliance with fluid intake recommendations of 2 L daily, 11,572 new stones might be prevented, resulting in a cost savings of €49 million. Compliance with water intake in only 25% of patients would still result in 2,893 fewer stones and a cost savings of €10 million. Varying the costs of managing stones had a smaller impact on outcomes since in many patients stones do not form. Varying the incidence of complications did not change the incidence of stones and had a negligible effect on overall cost.

CONCLUSIONS

Preventing recurrent urolithiasis has a significant cost savings potential for a payer as a result of a reduced stone burden. However, compliance is an important factor in determining cost-effectiveness.

Do kidney histology lesions predict long-term kidney function after liver transplantation?

Histological renal lesions observed after liver transplantation are complex, multifactorial, and interrelated. The aims of this study were to determine whether kidney lesions observed at five yr after liver transplantation can predict long-term kidney function. Ninety-nine liver transplant patients receiving calcineurin inhibitor (CNI)-based immunosuppression, who had undergone a kidney biopsy at 60±48 months post-transplant, were included in this follow-up study. Kidney biopsies were scored according to the Banff classification. Estimated glomerular filtration rate (eGFR) was assessed at last follow-up, that is, 109±48 months after liver transplantation. eGFR decreased from 92±33 mL/min at transplantation to 63±19 mL/min after six months, to 57±17 mL/min at the kidney biopsy, to 54±24 mL/min at last follow-up (p<0.0001). At last follow-up, only three patients required renal replacement therapy. After the kidney biopsy, 13 patients were converted from CNIs to mammalian target of rapamycin inhibitors, but no significant improvement in eGFR was observed after conversion. Elevated eGFR at six months post-transplant and a lower fibrous intimal thickening score (cv) observed at five yr post-transplant were the two independent predictive factors for eGFR≥60 mL/min at nine yr post-transplant. Long-term kidney function seems to be predicted by the kidney vascular lesions.

Bradykinin inhibits high glucose- and growth factor-induced collagen synthesis in mesangial cells through the B2-kinin receptor

Mesangial matrix expansion is an early lesion leading to glomeruloclerosis and chronic renal diseases. A beneficial effect is achieved with angiotensin I-converting enzyme inhibitors (ACEI), which also favor bradykinin (BK) B2 receptor (B2R) activation. To define the underlying mechanism, we hypothesized that B2R activation could be a negative regulator of collagen synthesis in mesangial cells (MC). We investigated the effect of BK on collagen synthesis and signaling in MC. Inflammation was evaluated by intercellular adhesion molecule-1 (ICAM-1) expression. BK inhibited collagen I and IV synthesis stimulated by high glucose, epithelial growth factor (EGF), and transforming growth factor-β (TGF-β) but did not alter ICAM-1. Inhibition of collagen synthesis was B2R but not B1R mediated. PKC or phosphatidylinositol 3-kinase (PI3K) inhibitors mimicked the BK effect. B2R activation inhibited TGF-β- and EGF-induced Erk1/2, Smad2/3, Akt S473, and EGFR phosphorylation. A phosphatase inhibitor prevented BK effects. The in vivo impact of B2R on mesangial matrix expansion was assessed in streptozotocin-diabetic rodents. Deletion of B2R increased mesangial matrix expansion and albuminuria in diabetic mice. In diabetic rats, matrix expansion and albuminuria were prevented by ACEI but not by ACEI and B2R antagonist cotreatment. Consistently, the lowered BK content of diabetic glomeruli was restored by ACEI. In conclusion, deficient B2R activation aggravated mesangial matrix expansion in diabetic rodents whereas B2R activation reduced MC collagen synthesis by a mechanism targeting Erk1/2 and Akt, common pathways activated by EGF and TGF-β. Taken together, the data support the hypothesis of an antifibrosing effect of B2R activation.

Impact of growth hormone hypersecretion on the adult human kidney

Acromegaly is most often secondary to a GH-secreting pituitary adenoma with increased Insulin-like Growth Factor type 1 (IGF-1) level. The consequences of GH/IGF-1 hypersecretion reflect the diversity of action of these hormones. The genes of the GH receptor (GHR), IGF-1, IGF-1 receptor (IGF-1R) and IGF-binding proteins (IGF-BP) are physiologically expressed in the adult kidney, suggesting a potential role of the somatotropic axis on renal structure and functions. The expression of these proteins is highly organized and differs according to the anatomical and functional segments of the nephron suggesting different roles of GH and IGF-1 in these segments. In animals, chronic exposure to high doses of GH induces glomerulosclerosis and increases albuminuria. Studies in patients with GH hypersecretion have identified numerous targets of GH/IGF-1 axis on the kidney: 1) an impact on renal filtration with increased glomerular filtration rate (GFR), 2) a structural impact with an increase in kidney weight and glomerular hypertrophy, and 3) a tubular impact leading to hyperphosphatemia, hypercalciuria and antinatriuretic effects. Despite the increased glomerular filtration rate observed in patients with GH hypersecretion, GH is an inefficient treatment for chronic renal failure. GH and IGF-1 seem to be involved in the physiopathology of diabetic nephropathy; this finding offers the possibility of targeting the GH/IGF-1 axis for the prevention and the treatment of diabetic nephropathy.

Risk factors of chronic kidney disease in HIV-infected patients

BACKGROUND AND OBJECTIVES

The main aim of this study was determining the risk factors of chronic kidney disease (CKD) in HIV-1-infected patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients were followed from seven large HIV reference centers in France that maintain prospective databases on HIV-1-infected patients. The main outcome was the time to CKD defined as two consecutive measures of estimated GFR ≤60 ml/min per 1.73 m² over ≥3 months. A Cox's model with delayed entry was used to search predictive factors of time to CKD.

RESULTS

From 1993 to 2006, 349 out of 7378 patients were found to have CKD. Of these, 166 had hypertension, 33 had diabetes, and 26 were antiretroviral therapy-naïve. Occurrence of acute kidney injury (hazard ratio [HR] = 2.40) and hypertension (HR = 2.39) were strongly associated with an increased risk of CKD. Patients with a durable level of CD4 count >200 cells/mm³ had a lower risk of CKD (HR = 0.63). Recent exposure to indinavir (HR = 2.03), totenofovir (HR = 1.55), and abacavir (HR = 1.37) were associated with an increased risk of CKD. Past exposure to tenofovir was also associated with an increased risk of CKD (HR = 2.23), and a trend toward significance was observed for past exposure to indinavir (HR = 1.28).

CONCLUSIONS

CKD was not rare in HIV-infected patients and occurs preferentially in HIV-infected patients exposed to certain ARVs, specifically abacavir, indinavir and tenofovir. This requires closer monitoring of renal function in patients exposed to one of these drugs.