Association of HLA B- and T-cell molecular mismatches with HLA antibodies, rejection, and graft survival in pediatric kidney transplantation.

BACKGROUND: Optimizing graft survival and diminishing human leukocyte antigen (HLA) sensitization are essential for pediatric kidney transplant recipients. More precise HLA matching predicting epitope mismatches could reduce alloreactivity. We investigated the association of predicted HLA B- and T-cell molecular mismatches with the formation of de novo donor-specific antibodies, HLA antibodies, rejection, and graft survival. METHODS: Forty-nine pediatric kidney transplant recipients transplanted from 2009 to 2020 were retrospectively studied. Donors and recipients were high-resolution HLA typed, and recipients were screened for HLA antibodies posttransplant. HLA-EMMA (HLA Epitope MisMatch Algorithm) and PIRCHE-II (Predicted Indirectly ReCognizable HLA Epitopes) predicted the molecular mismatches. The association of molecular mismatches and the end-points was explored with logistic regression. RESULTS: Five recipients (11%) developed de novo donor-specific antibodies. All five had de novo donor-specific antibodies against HLA class II, with four having HLA-DQ antibodies. We found no associations between PIRCHE-II or HLA-EMMA with de novo donor-specific antibodies, HLA sensitization, graft loss, or rejection. However, we did see a tendency towards an increased odds ratio in PIRCHE-II predicting de novo donor-specific antibodies formation, with an odds ratio of 1.12 (95% CI: 0.99; 1.28) on HLA class II. CONCLUSION: While the study revealed no significant associations between the number of molecular mismatches and outcomes, a notable trend was observed - indicating a reduced risk of dnDSA formation with improved molecular match. It is important to acknowledge, however, that the modest population size and limited observed outcomes preclude us from making definitive conclusions.

Exploration of complement split products in plasma and urine as biomarkers of kidney graft rejection.

INTRODUCTION: The complement system, consisting of more than thirty different soluble and cell-bound proteins, exerts essential functions both in the innate and adaptive immune systems and is believed to be an important contributor to allograft injury in kidney transplantation. The anaphylatoxins C3a and C5a are powerful chemoattractants, recruiting immune effector cells toward the site of complement activation and enhance T-cell response, while C3dg binding to CR2 on B-cells, enhances B-cell immunity at several stages of the B-cell differentiation. Complement split products in plasma and urine could reflect ongoing inflammation and tissue injury. We, therefore, investigated if complement split products increase in plasma and urine in kidney transplant recipients with rejection. METHOD: In this case-control feasibility study, complement factors C3a, C3dg, C4a, and C5a were measured in plasma and C3dg and sC5b-9 associated C9 neoantigen in urine in 15 kidney transplant recipients with rejection (cases) and 15 kidney transplant recipients without (controls). The groups were matched on the type of transplantation and the time from transplantation to sampling. The complement split products were compared (i) between cases and controls and (ii) within the rejection group over time, comparing the measurements at rejection with measurements where the kidney transplant recipients were clinically stable. Possible moderators were explored, and results adjusted accordingly. P values < 0.05 were considered significant. Plasma C3dg was analyzed by immune-electrophoresis, plasma C3a, plasma C4a, and plasma C5a by flow cytometry, and urine C3dg and urine C9neo by ELISA. RESULTS: In plasma, there were no significant differences between the rejection and the control group. However, steroids and pretransplant C3dg levels significantly influenced C3dg. Within the rejection group, plasma C3a and C3dg were significantly higher at the time of rejection compared to the stable phase (p < 0.01). In urine, C3dg/creatinine and C9 neoantigen/creatinine ratios were not different between the rejection and the control group. Urine C3dg/creatinine and urine C9 neoantigen/creatinine ratios correlated to urine albumin and significantly increased after the transplantation (p < 0.001). CONCLUSION: This study shows increased plasma C3a and C3dg in kidney transplant recipients, primarily with T cell mediated rejection. This finding suggests that consecutive measurements of C3a and C3dg in plasma could be applicable to monitor alloreactivity in kidney transplant recipients. Urine complement split products are unsuitable as rejection biomarkers since the permeability of the glomerular filtration barrier strongly influences them. Prospective longitudinal studies on plasma C3a and C3dg dynamics will be needed to validate present findings.

Relationships and dynamics in families with a child with a kidney transplant-A study of parents' everyday life experiences.

BACKGROUND: Paediatric kidney transplantation is often the best choice of treatment for kidney failure with replacement therapy and represents an important change in the child's well-being. There are, however, still a number of challenges in addition to the parental role. The magnitude of intensive parental caregiving and support required by children with a kidney transplant could be disruptive to family relationships and dynamics. OBJECTIVE: To explore the experiences of family relationships and dynamics among parents of a child with a kidney transplant. DESIGN: An explorative study using a qualitative method. PARTICIPANTS: Twelve parents (seven mothers and five fathers) of seven children with a kidney transplant were included. APPROACH: A phenomenological-hermeneutic approach was applied. METHOD: Semistructured, individual interviews were conducted. The data were analysed using Ricoeur's theory of interpretation on three levels: naïve reading, structural analysis and critical interpretation and discussion. FINDINGS: Three themes were generated: Emotions during ups and downs in everyday life; Balancing different needs among children; and Opportunities and having consideration in the family. CONCLUSION: Relationships between parents that are based on mutual emotional support are significant and essential during periods of severe illness in a child. Parents who are alone or emotionally marked by their child's disease history feel vulnerable and struggle to overcome challenges. Different health situations among siblings lead to challenges in bringing up the children and emotional dilemmas among parents that impact family dynamics. Resilience in parents is a shifting phenomenon that can influence how they deal with family relationships and dynamics.

Parenting a child with a kidney transplant-A study of everyday life experiences.

BACKGROUND: Kidney transplantation in children shows excellent long-term outcomes. However, parents feel responsible for ensuring that their child adheres to complex medical interventions. The dual role - as both parent and medical caregiver - gives rise to fatigue, stress, and emotional pain. Parental and family functioning are critically important to a child's disease course, development and well-being. OBJECTIVE: To explore the experiences and perspectives of mothers and fathers of children with a kidney transplant. DESIGN: An explorative study using a qualitative method. PARTICIPANTS: Twelve parents (seven mothers and five fathers) of seven children with a kidney transplant. APPROACH: A qualitative exploratory study taking a phenomenological-hermeneutic approach. METHOD: Semi-structured individual interviews were conducted. The data were analysed using Ricoeur's theory of narrative and interpretation on three levels: naïve reading, structural analysis, and critical interpretation and discussion. FINDINGS: Four themes were generated: Kidney transplantation as a turning point, the importance of a close collaboration with health care professionals, being the child's voice, and managing the dual role as a parent, and medical caregiver in everyday life. CONCLUSION: Child kidney transplantation led to a transformation in the child, on the physical, mental, and social levels; however, the child was still in need of special attention and support. Problems with the kidney graft functioning resulted in frustration and disappointment in parents. Teamwork between a child's parents became evident, in coping with the dual role as a parent and medical caregiver. Parents aimed to maintain a clear structure related to medication and disease-related treatment. A close and trustful relationship and collaboration with health care professionals were significant and included listening to the voice of the child.

Siblings of children with chronic kidney disease: A qualitative study of everyday life experiences.

BACKGROUND: Chronic kidney disease in children has an impact on all family members. Healthy siblings, in particular, may experience negative psychological and emotional symptoms. Little attention has been paid to how they experience everyday family life and the impact of their sibling's disease. OBJECTIVES: To explore perspectives on and experiences of everyday life among siblings of children with chronic kidney disease. DESIGN: An explorative study with a qualitative method. PARTICIPANTS: Seven siblings (7-13 years) of children with chronic kidney disease (5-16 years) were included. APPROACH: The study took a phenomenological-hermeneutical approach. Semistructured individual interviews were conducted. The data were analysed using Ricoeur's theory of narrative and interpretation, on three levels: naïve reading, structural analysis and critical interpretation and discussion. FINDINGS: Three themes emerged: The illness is in the background or comes to the fore, being concerned for and taking care of the sick sibling and the importance of bonds with relatives or other significant adults. CONCLUSION: In everyday life, participants experienced that their sick sibling's illness was either in the background or came to the fore. They needed to adapt to periods of hospitalisation. They felt a need to be attentive to, take care of and have concern for the sick brother or sister. Conflicts caused feelings of loneliness; however, having knowledge about the disease provided security and meaning. Being introduced to the healthcare professionals was significant. It was important to have close relationships with friends and other adults, which gave rise to feelings of self-confidence and being supported.

The significance of relationships and dynamics in families with a child with end-stage kidney disease: A qualitative study.

AIM AND OBJECTIVES: To explore experiences and the significance of relationships and dynamics among family members living with a child with severe kidney disease. BACKGROUND: Chronic kidney disease (CKD) in children is often incurable, leading to irreversible kidney damage. End-stage kidney failure in a child impacts daily life and routines, requiring significant social adaptation for all family members. However, little is known about how individual family members experience relationships, interactions and dynamics within the family. DESIGN: A qualitative exploratory study taking a phenomenological-hermeneutic approach. METHOD: Data were collected through semi-structured individual interviews with seven fathers, seven mothers, five children with end-stage kidney disease and five siblings. The data were analysed using Ricoeur's theory of narrative and interpretation, on three levels: naïve reading; structural analysis; and critical interpretation and discussion. The Consolidated Criteria for Reporting Qualitative Research checklist has been used (see Supporting Information). RESULTS: All family members experienced relationships within and outside the family as a significant part of everyday life. The well-being of the sick child had an impact on the dynamics and emotional well-being of all family members. Siblings were in need of support; however, being fair could be challenging for parents. CONCLUSION: CKD in a child has an impact on family dynamics and on the relationships between family members. Family members are vulnerable and in need of practical help and emotional support from close relatives, friends, health professionals and other individuals around them. RELEVANCE TO CLINICAL PRACTICE: In clinical practice, the ability to reflect on, or interpret, a range of situations by initiating a dialogue is essential to shape both an individual perspective and the perspective of the entire family unit.

Everyday life experiences in families with a child with kidney disease.

BACKGROUND: Chronic kidney disease in children is a complex medical and psychosocial disease with factors that differ from the adult disease in significant ways. Among parents, there is uncertainty about disease progression and lack of confidence in caring for the child. The disease has an impact on the emotional and social well-being of the whole family. OBJECTIVES: To investigate everyday life experiences from the perspectives of members of a family that includes a child with end stage renal disease. METHOD: The study took a phenomenological-hermeneutical approach. Semi-structured individual interviews were conducted with seven fathers, seven mothers, five children with kidney disease and five siblings. The data were analysed using Ricoeur's theory of narrative and interpretation, on three levels: naïve reading, structural analysis, critical interpretation and discussion. RESULTS: It was significant that everyday life and caring for the child were structured around parents' energy reserves. The disease left its mark and changes to daily life caused anxiety, especially for siblings. The search for normalcy was significant and, although the families coped with conditions around the disease, it could be a challenge. CONCLUSION: Family members feel vulnerable and concerned and need attention, support and care. Limitations in everyday life cause a dilemma, and the well-being of one family member has an impact on the well-being of the family as a whole. IMPLICATIONS FOR PRACTICE: Health care professionals should focus on the impact of the family's experiences and needs, and the parents' role in family relationships, to support the entire family unit.

Effect of spironolactone for 1 yr on endothelial function and vascular inflammation biomarkers in renal transplant recipients.

Kidney transplantation is associated with increased cardiovascular risk. Endothelial dysfunction and vascular inflammation contribute to negative outcome. In experimental models, mineralocorticoid receptor antagonists improved endothelial function and reduced inflammation. The present study tested the hypothesis that the mineralocorticoid receptor antagonist spironolactone improves endothelial function and reduces vascular inflammation in renal transplant patients. Eighty prevalent renal transplant patients from an ongoing, double-blind randomized placebo-controlled trial were included. Paired plasma samples before and after 1 yr of treatment (n = 39 in the spironolactone-treated group and 41 in the placebo-treated group) were used to determine markers of endothelial dysfunction (nitrite, nitrate, cGMP, arginine, citrulline, ornithine, asymmetric dimethylarginine, symmetric dimethylarginine, NG-monomethyl-l-arginine, von Willebrand factor, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor 1 antigen) and markers of inflammation (intercellular adhesion molecule, vascular adhesion molecule, high-sensitivity C-reactive protein, and serum amyloid protein A). The median time since the transplantation was 4.6 (0.12-22.3) yr in the spironolactone-treated group and 2.1 (0.17-13.9) yr in the placebo-treated group (P > 0.05). Spironolactone increased plasma aldosterone (P < 0.001) and K+ (P < 0.001). Blood pressure did not change significantly. No significant differences were detected between groups in any of the measured markers of endothelial dysfunction or inflammation except in the subgroup analysis of patients with diabetes, where spironolactone decreased nitrite compared with placebo. In this study, mineralocorticoid receptor antagonism did not improve biomarkers of endothelial dysfunction or vascular inflammation in prevalent renal transplant patients. Further studies are needed to evaluate the potential beneficial effect of early or late mineralocorticoid receptor antagonism on vascular outcomes in renal transplant patients.

The effect of spironolactone on calcineurin inhibitor induced nephrotoxicity: a multicenter randomized, double-blind, clinical trial (the SPIREN trial).

BACKGROUND: Calcineurin inhibitor induced nephrotoxicity contributes to late allograft failure in kidney transplant patients. Evidence points towards aldosterone to play a role in the development of fibrosis in multiple organs. Animal studies have indicated a beneficial effect of mineralocorticoid receptor antagonists preventing calcineurin inhibitor induced nephrotoxicity. Only few studies have explored this effect in humans. The objective of this study is to evaluate the effect of spironolactone on glomerular filtration rate and fibrosis in kidney transplant patients. METHOD: Prospective, double-blind, randomized, clinical trial including 170 prevalent kidney transplant patients. Patients are randomized to spironolactone 25-50 mg/day or placebo for three years. Primary outcome is glomerular filtration rate evaluated by chrome-EDTA clearance. Secondary outcomes are 24-h protein excretion, amount of interstitial fibrosis in renal allograft biopsies, and cardiovascular events. As an exploratory outcome, we aim to identify markers of fibrosis in blood and urine. DISCUSSION: Long term allograft survival remains a key issue in renal transplantation, partly due to calcineurin inhibitor induced nephrotoxicity. Evidence from animal- and small human studies indicate a beneficial effect of mineralocorticoid receptor antagonism on renal function and fibrosis. This study aims to test this hypothesis in a sufficiently powered randomized clinical trial. Results might influence the future management of long term allograft survival in renal transplantation. TRIAL REGISTRATION: ClinicalTrials.gov identifier (05/17/2012): NCT01602861 . EudraCT number (05/31/2011): 2011-002243-98.

Internal dysregulation of the renin system in patients with stable liver cirrhosis.

Sodium retention in cirrhosis is associated with changes in the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system (SNS), and the glomerular filtration rate (GFR). We hypothesized that in cirrhosis the acute reactions of RAAS and SNS to volume expansion are qualitatively intact, but occurring from elevated baseline levels. Acute cardiovascular, neurohumoral and renal responses to central blood volume changes were studied in cirrhotic patients and healthy controls. In patients, baseline plasma renin concentration (PRC) was elevated 5-fold compared to controls (p < .001); it increased during standing (+144%, p < .001) and remained elevated during subsequent sitting (+118%, p < .001). At baseline, plasma angiotensin II (pANGII) was not elevated significantly (14 ± 2 vs. 9 ± 2 pg/mL) in contrast to plasma aldosterone (pAldo, +160%, p < .001). During orthostatic RAAS activation, the rise in pAngII per unit increase in PRC was 0.04 pg AngII/mIU and 0.48 pg AngII/mIU in patients and controls, respectively (p < .001); similarly, the change in pAldo per unit change in pANGII was 3.6 in patients and 14.5 pg/pg in controls (p < .001). Plasma noradrenaline was elevated in the patients, but the dynamic changes were virtually identical to those of controls. During standing, abrupt decreases in renal blood flow (-63%, p < .001) and GFR (-42% p < .04) occurred only in patients. In conclusion, in stable cirrhosis, static and dynamic dysregulation exists within the RAAS; in the supine position pAngII levels are inappropriately low, and the AngII-mediated regulation of aldosterone secretion is severely impeded. In cirrhotic patients, profound reductions in renal blood flow and GFR occur during standing.

The second report of the Nordic Pediatric Renal Transplantation Registry 1997-2012: More infant recipients and improved graft survivals.

The NPRTSG has collected data on pediatric KTx since 1994. The registry archives information from all centers that perform pediatric KTx in Denmark, Finland, Norway, and Sweden and has 100% coverage. The first NPRTSG report was published in 1998 and was based on data collected in the 1982─1996 period. The present report provides data on 602 pediatric KTx in the Nordic countries from 1997 to 2012. Comparison of the patient demographics and one- and three-yr graft survivals between the two time cohorts revealed no significant change in the recipient and donor demographics. The number of transplantations increased by approximately 30%, doubling the recipients below the age of two yr. The use of Tac and mycophenolate as primary immunosuppression increased from practically 0% to 50% and 40%, respectively. The one- and three-yr graft survivals improved significantly (p < 0.001), especially among the youngest recipients with transplant from DD. In these patients, the one-yr survival improved from 70% to 94.6% and the three-yr graft survival from 60% to 94.6%, respectively. The improved graft survival may be at least partly due to changes in immunosuppression strategies, but also greater experience may also be of importance.

Long-term experience of steroid-free pediatric renal transplantation: effects on graft function, body mass index, and longitudinal growth.

Increased focus on the potential negative side effects of steroid usage in pediatric transplantation has led to steroid minimization or steroid-free transplantation. In this study, we report results after complete steroid avoidance in renal transplantation in the period 1994-2009. We evaluate the effects of complete steroid avoidance on allograft function, BMI, and linear growth. The majority of transplanted children were induced with antithymocyte globulin and immunosuppressed with a calcineurin inhibitor and mycophenolate mofetil. Steroids were given only when rejection occurred or due to comorbidities. Anthropometric data were collected from 65 transplantations in 60 children. Patient survival was 93%; graft survival was 81% after five yr (N = 42) and 63% after 10 yr (N = 16). Acute rejection within the first year of transplantation was 9%. The distribution of the children's BMI before transplantation was normal; the mean BMI-SDS was 0.21 before transplantation, and this value remained stable during the next five yr. Post-transplantation the children demonstrated significant improved growth as the mean height-SDS increased significantly from -1.7 to -1.1. Catch-up growth was most pronounced in the youngest (< six yr). Steroid-free immunosuppression in pediatric renal transplantation is safe and protects against steroid-induced obesity and short stature.

The renal arterial resistive index and stage of chronic kidney disease in patients with renal allograft.

OBJECTIVE: The study investigated the optimal threshold value of renal arterial resistive index as assessed by Doppler ultrasonography determining chronic kidney disease stage 4 or higher in patients with renal allograft. METHODS: In a cross-sectional study the renal arterial resistive index were obtained in interlobar arteries by Doppler ultrasonography in 78 patients with renal allograft. The stage of chronic kidney disease was determined by the estimated glomerular filtration rate equation. RESULTS: The median renal arterial resistive index was 0.61 (interquartile range, 0.56 to 0.66). We observed a significant association between renal arterial resistive index above the upper quartile and chronic kidney disease stage 4 or higher (relative risk, 4.64; 95% confidence interval, 1.71 to 12.55; p = 0.003 by Fisher's exact test). Multivariate logistic regression analysis showed that renal arterial resistive indices (p = 0.02) and time since transplantation (p = 0.04), but not age, gender, or blood pressure were significantly associated with chronic kidney disease stage 4 or higher. CONCLUSION: A renal arterial resistive index higher than 0.66 may determine the threshold value of chronic kidney disease stage 4 or higher in patients with renal allograft.

[Renal failure in a couple caused by Puumala hantavirus]. / Nyresvigt hos ægtepar forårsaget af Puumala-Hantavirus.

In Scandinavia Puumala hantavirus causes nephropathia epidemica (NE), characterised by an acute debut of fever, headache, increasing back and abdominal pain, thrombocytopenia, increasing azotemia parameters, as well as microscopic haematuria and mild proteinuria. In some cases transitory myopia can be found. The diagnosis is made with a relevant clinical history and serology, and in most cases a kidney biopsy is not necessary. There is a risk of missing cases of NE as in this case, where a couple became infected by Puumala Hantavirus in a high-risk area but became ill in an area with a low prevalence.

Bile acids modulate glucocorticoid metabolism and the hypothalamic-pituitary-adrenal axis in obstructive jaundice.

BACKGROUND & AIMS: Suppression of the hypothalamic-pituitary-adrenal axis occurs in cirrhosis and cholestasis and is associated with increased concentrations of bile acids. We investigated whether this was mediated through bile acids acting to impair steroid clearance by inhibiting glucocorticoid metabolism by 5beta-reductase. METHODS: The effect of bile acids on glucocorticoid metabolism was studied in vitro in hepatic subcellular fractions and hepatoma cells, allowing quantitation of the kinetics and transcript abundance of 5beta-reductase. Metabolism was subsequently examined in vivo in rats following dietary manipulation or bile duct ligation. Finally, glucocorticoid metabolism was assessed in humans with obstructive jaundice. RESULTS: In rat hepatic cytosol, chenodeoxycholic acid competitively inhibited 5beta-reductase (K(i) 9.19+/-0.40 microM) and reduced its transcript abundance (in H4iiE cells) and promoter activity (reporter system, HepG2 cells). In Wistar rats, dietary chenodeoxycholic acid (1% w/w chow) inhibited hepatic 5beta-reductase activity, reduced urinary excretion of 3alpha,5beta-tetrahydrocorticosterone and reduced adrenal weight. Conversely, a fat-free diet suppressed bile acid levels and increased hepatic 5beta-reductase activity, supplementation of the fat-free diet with CDCA reduced 5beta-reductase activity, and urinary 3alpha,5beta-reduced corticosterone. Cholestasis in rats suppressed hepatic 5beta-reductase activity and transcript abundance. In eight women with obstructive jaundice, relative urinary excretion of 3alpha,5beta-tetrahydrocortisol was significantly lower than in healthy controls. CONCLUSION: These data suggest a novel role for bile acids in inhibiting hepatic glucocorticoid clearance, of sufficient magnitude to suppress hypothalamic-pituitary-adrenal axis activity. Elevated hepatic bile acids may account for adrenal insufficiency in liver disease.

Differential effects of immunosuppressive drugs on COX-2 activity in vitro and in kidney transplant patients in vivo.

BACKGROUND: It was hypothesized that calcineurin inhibitors suppress vascular cyclooxygenase (COX)-2 and exert a reciprocal influence on in vivo prostacyclin and thromboxane. This could contribute to cardiovascular morbidity in transplanted patients. METHODS: The ability of immunosuppressives to suppress vascular COX-2 expression in vitro was studied in cultured human vascular smooth muscle cells. Blood and urine samples were collected from 28 renal transplant patients before and 2, 4 and 6 h after intake of immunosuppressives and from 11 controls. ELISA was used to measure (1) plasma 6-keto-PGF1alpha and TxB2; (2) urine excretion of PGI-M and TxB(2); (3) 6-keto-PGF1alpha in the whole-blood COX-2 assay; and (4) TxB2 in the whole-blood COX-1 assay. Platelet aggregation was measured optically. RESULTS: COX-2 in cultured vascular smooth muscle cells was suppressed by cyclosporine A (CsA); tacrolimus and rapamycin had no effect. Human renal arteries and vascular smooth muscle expressed calcineurin Abeta and Agamma isoforms. CsA had no effect on plasma 6-keto-PGF1alpha, whole-blood COX-2 activity or PGI-M urine excretion; after rapamycin intake, the former two increased. Plasma TxB2 did not change after drug intake. TxB2 in the COX-1 assay and urine excretion of TxB2 was significantly lower in tacrolimus- and rapamycin-treated patients compared to the CsA group. Platelet aggregation was increased significantly in the CsA group. CONCLUSIONS: Although CsA suppressed COX-2 in cultured vascular smooth muscle cells, systemic prostacyclin was not suppressed by either CsA or tacrolimus in vivo. Rapamycin and tacrolimus may actively suppress platelet and renal thromboxane formation. Differential changes in prostanoids may have implications for long-term cardiovascular hazard in patients treated with immunosuppressives.

Plasmin in nephrotic urine activates the epithelial sodium channel.

Proteinuria and increased renal reabsorption of NaCl characterize the nephrotic syndrome. Here, we show that protein-rich urine from nephrotic rats and from patients with nephrotic syndrome activate the epithelial sodium channel (ENaC) in cultured M-1 mouse collecting duct cells and in Xenopus laevis oocytes heterologously expressing ENaC. The activation depended on urinary serine protease activity. We identified plasmin as a urinary serine protease by matrix-assisted laser desorption/ionization time of-flight mass spectrometry. Purified plasmin activated ENaC currents, and inhibitors of plasmin abolished urinary protease activity and the ability to activate ENaC. In nephrotic syndrome, tubular urokinase-type plasminogen activator likely converts filtered plasminogen to plasmin. Consistent with this, the combined application of urokinase-type plasminogen activator and plasminogen stimulated amiloride-sensitive transepithelial sodium transport in M-1 cells and increased amiloride-sensitive whole-cell currents in Xenopus laevis oocytes heterologously expressing ENaC. Activation of ENaC by plasmin involved cleavage and release of an inhibitory peptide from the ENaC gamma subunit ectodomain. These data suggest that a defective glomerular filtration barrier allows passage of proteolytic enzymes that have the ability to activate ENaC.

Report of the first human case of Caulobacter sp. infection.

A Caulobacter sp. isolate was recovered from the dialysis fluid of a patient undergoing peritoneal dialysis. Bacterial identification included electron microscopy and 16S rDNA sequencing. To our knowledge, this is the first report of human Caulobacter infection. Special growth requirements suggest that Caulobacter spp. may be overlooked in the clinical microbiology laboratory.

Renal sodium retention in cirrhotic rats depends on glucocorticoid-mediated activation of mineralocorticoid receptor due to decreased renal 11beta-HSD-2 activity.

Downregulation of the renal glucocorticoid-metabolizing enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD-2) during liver cirrhosis may allow activation of the mineralocorticoid receptor (MR) by glucocorticoids and contribute to sodium retention. We tested this hypothesis in male Wistar rats with decompensated liver cirrhosis and ascites 7 wk after bile duct ligation (BDL). Renal 11beta-HSD-2 mRNA, protein, and activity were significantly decreased in decompensated rats. The urinary Na(+)/K(+) ratio was reduced by 40%. Renal epithelial sodium channel (ENaC) mRNA and immunostaining were only slightly affected. Complete metabolic studies, including fecal excretion, showed that the BDL rats had avid renal sodium retention. Treatment of the BDL rats with dexamethasone suppressed endogenous glucocorticoid production, normalized total sodium balance and renal sodium excretion, and reduced ascites formation to the same degree as direct inhibition of MR with K-canrenoate. Total potassium balance was negative in the BDL rats, whereas renal potassium excretion was unchanged. In the distal colon, expression of ENaC was increased in BDL rats. Fecal potassium excretion was increased in cirrhotic rats, and this was corrected by treatment with K-canrenoate but not dexamethasone. We conclude that development of sodium retention and decompensation in cirrhotic rats is associated with downregulation of renal 11beta-HSD-2 activity and inappropriate activation of renal sodium reabsorption by endogenous glucocorticoids. In addition, the overall potassium loss in the BDL model is due to increased fecal potassium excretion, which is associated with upregulation of ENaC in distal colon.