Fabry Disease Presenting as End-Stage Kidney Disease.

Background: Fabry disease (FD) is an X-linked disorder due to a pathogenic variant of the GLA gene that codes for the alpha-galactosidase enzyme. The reduced or absent activity of the enzyme results in lysosomal accumulation of globotriosylceramide and its derivative, globotriaosylsphingosine, in a variety of cells, leading to a variety of complications including cardiac, renal, and cerebrovascular disorders. Early diagnosis is critically important for the selection of therapeutic treatments, which are essential for improving outcomes. Here we present a case of FD diagnosed at the time of end-stage kidney disease presentation. Summary: A 40-year-old man with a history of seizures presented with increased serum creatinine, nephrotic rage proteinuria, and new-onset hypertension. A renal biopsy revealed numerous, whorled, and lamellated cytoplasmic inclusions in podocytes, glomerular peritubular capillary endothelial cells, mesangial cells, arterial myocytes, and interstitial macrophages. Ultrastructural analysis confirmed the presence of glycosphingolipid inclusions and enlarged lysosomes packed with multi-lamellated structures ("zebra" bodies). The findings were suggestive of a lysosomal storage disorder, and testing for alpha-galactosidase A levels revealed near-absent enzyme activity, confirming the diagnosis of advanced FD. Key Messages: The diagnosis of FD can be challenging as the manifestations of the disease are nonspecific, and patients can present early with classical symptoms or late with non-classical patterns of involvement. We will discuss strategies to identify the disorder early by reviewing the classical and non-classical presentations and further outline currently available and potential future treatment options.

The effect of the interdialytic interval on cognitive function in patients on haemodialysis.

BACKGROUND: Cognitive deficits are common among individuals on haemodialysis (HD). The degree of dysfunction may shift over the course of the interdialytic interval. OBJECTIVES: To use ecological momentary assessment (EMA) to examine the relationship between the length of the interdialytic interval and reports of cognitive dysfunction. DESIGN: A quantitative study whereby each patient's cognitive functioning was measured during both short and long interdialytic intervals. PARTICIPANTS: Adults maintained on HD (Female n = 15, Male n = 11; MAge = 42.7 ± 15.8 years) were drawn from a standalone HD unit within a large university medical centre. MEASUREMENTS: Tests of baseline neurocognitive functioning were undertaken (Mini-Mental Status Examination, Digit Span, California Verbal Learning Test, Benton Visual Retention Test, Trail-Making Test) and smartphone-based electronic diary reports of cognitive impairment were made around six times each day for one week. RESULTS: Cognitive function and aptitude in this sample, although low, did not reflect clinically-significant impairment, with a mean Mini-Mental Status Exam score of 25.7 ± 3.0. Diary reports of cognitive impairment were also minimal, with an overall mean rating of .22 out of 5. Contrary to expectations, cognitive impairment was significantly greater on the one-day interdialytic days than on Day 2 of the two-day interdialytic interval (ß = .094, p = .017). CONCLUSIONS: Although cognitive impairment appears to be mild in stable, young patients with end stage renal disease, volumetric disruptions caused by HD may exacerbate such dysfunction.

Effects of end-stage renal disease and dialysis modalities on blood ammonia level.

INTRODUCTION: Uremia results in a characteristic breath odor (uremic fetor) which is largely due to its high ammonia content. Earlier studies have shown a strong correlation between breath ammonia and blood urea levels and a 10-fold reduction in breath ammonia after hemodialysis in patients with chronic kidney disease. Potential sources of breath ammonia include: (i) local ammonia production from hydrolysis of urea in the oropharyngeal and respiratory tracts by bacterial flora, and (ii) release of circulating blood ammonia by the lungs. While the effects of uremia and hemodialysis on breath ammonia are well known their effects on blood ammonia are unknown and were explored here. METHODS: Blood samples were obtained from 23 hemodialysis patients (immediately before and after dialysis), 14 peritoneal dialysis patients, and 10 healthy controls. Blood levels of ammonia, creatinine, urea, and electrolytes were measured. FINDINGS: No significant difference was found in baseline blood ammonia between hemodialysis, peritoneal dialysis and control groups. Hemodialysis procedure led to a significant reduction in urea concentration (P < 0.001) which was paradoxically accompanied by a modest but significant (P < 0.05) rise in blood ammonia level in 10 of the 23 patients studied. Change in blood ammonia pre- and post-hemodialysis correlated with change in serum bicarbonate levels (r = 0.61, P < 0.01). On subgroup analysis of patients who had a rise in blood ammonia levels after dialysis, there was a strong correlation with drop in mean arterial pressure (r = 0.88, P < 0.01). The nadir intradialytic systolic blood pressure trended lower in the hemodialysis patients who had a rise in blood ammonia compared to the patients who manifested a fall in blood ammonia (124 ± 8 vs. 136 ± 6 mmHg respectively, P = 0.27). DISCUSSION: Fall in blood urea following hemodialysis in ESRD patients was paradoxically accompanied by a modest rise in blood ammonia levels in 43% of the patients studied, contrasting prior reported effects of hemodialysis on breath ammonia. In this subgroup of patients, changes in blood ammonia during hemodialysis correlated with rise in blood bicarbonate and fall in mean arterial blood pressure.

Selecting SNPs informative for African, American Indian and European Ancestry: application to the Family Investigation of Nephropathy and Diabetes (FIND).

BACKGROUND: The presence of population structure in a sample may confound the search for important genetic loci associated with disease. Our four samples in the Family Investigation of Nephropathy and Diabetes (FIND), European Americans, Mexican Americans, African Americans, and American Indians are part of a genome- wide association study in which population structure might be particularly important. We therefore decided to study in detail one component of this, individual genetic ancestry (IGA). From SNPs present on the Affymetrix 6.0 Human SNP array, we identified 3 sets of ancestry informative markers (AIMs), each maximized for the information in one the three contrasts among ancestral populations: Europeans (HAPMAP, CEU), Africans (HAPMAP, YRI and LWK), and Native Americans (full heritage Pima Indians). We estimate IGA and present an algorithm for their standard errors, compare IGA to principal components, emphasize the importance of balancing information in the ancestry informative markers (AIMs), and test the association of IGA with diabetic nephropathy in the combined sample. RESULTS: A fixed parental allele maximum likelihood algorithm was applied to the FIND to estimate IGA in four samples: 869 American Indians; 1385 African Americans; 1451 Mexican Americans; and 826 European Americans. When the information in the AIMs is unbalanced, the estimates are incorrect with large error. Individual genetic admixture is highly correlated with principle components for capturing population structure. It takes ~700 SNPs to reduce the average standard error of individual admixture below 0.01. When the samples are combined, the resulting population structure creates associations between IGA and diabetic nephropathy. CONCLUSIONS: The identified set of AIMs, which include American Indian parental allele frequencies, may be particularly useful for estimating genetic admixture in populations from the Americas. Failure to balance information in maximum likelihood, poly-ancestry models creates biased estimates of individual admixture with large error. This also occurs when estimating IGA using the Bayesian clustering method as implemented in the program STRUCTURE. Odds ratios for the associations of IGA with disease are consistent with what is known about the incidence and prevalence of diabetic nephropathy in these populations.

Altered intestinal microbial flora and impaired epithelial barrier structure and function in CKD: the nature, mechanisms, consequences and potential treatment.

Chronic kidney disease (CKD) results in systemic inflammation and oxidative stress which play a central role in CKD progression and its adverse consequences. Although many of the causes and consequences of oxidative stress and inflammation in CKD have been extensively explored, little attention had been paid to the intestine and its microbial flora as a potential source of these problems. Our recent studies have revealed significant disruption of the colonic, ileal, jejunal and gastric epithelial tight junction in different models of CKD in rats. Moreover, the disruption of the epithelial barrier structure and function found in uremic animals was replicated in cultured human colonocytes exposed to uremic human plasma in vitro We have further found significant changes in the composition and function of colonic bacterial flora in humans and animals with advanced CKD. Together, uremia-induced impairment of the intestinal epithelial barrier structure and function and changes in composition of the gut microbiome contribute to the systemic inflammation and uremic toxicity by accommodating the translocation of endotoxin, microbial fragments and other noxious luminal products in the circulation. In addition, colonic bacteria are the main source of several well-known pro-inflammatory uremic toxins such as indoxyl sulfate, p-cresol sulfate, trimethylamine-N-oxide and many as-yet unidentified retained compounds in end-stage renal disease patients. This review is intended to provide an overview of the effects of CKD on the gut microbiome and intestinal epithelial barrier structure and their role in the pathogenesis of systemic inflammation and uremic toxicity. In addition, potential interventions aimed at mitigating these abnormalities are briefly discussed.

Genome-Wide Association and Trans-ethnic Meta-Analysis for Advanced Diabetic Kidney Disease: Family Investigation of Nephropathy and Diabetes (FIND).

Diabetic kidney disease (DKD) is the most common etiology of chronic kidney disease (CKD) in the industrialized world and accounts for much of the excess mortality in patients with diabetes mellitus. Approximately 45% of U.S. patients with incident end-stage kidney disease (ESKD) have DKD. Independent of glycemic control, DKD aggregates in families and has higher incidence rates in African, Mexican, and American Indian ancestral groups relative to European populations. The Family Investigation of Nephropathy and Diabetes (FIND) performed a genome-wide association study (GWAS) contrasting 6,197 unrelated individuals with advanced DKD with healthy and diabetic individuals lacking nephropathy of European American, African American, Mexican American, or American Indian ancestry. A large-scale replication and trans-ethnic meta-analysis included 7,539 additional European American, African American and American Indian DKD cases and non-nephropathy controls. Within ethnic group meta-analysis of discovery GWAS and replication set results identified genome-wide significant evidence for association between DKD and rs12523822 on chromosome 6q25.2 in American Indians (P = 5.74x10-9). The strongest signal of association in the trans-ethnic meta-analysis was with a SNP in strong linkage disequilibrium with rs12523822 (rs955333; P = 1.31x10-8), with directionally consistent results across ethnic groups. These 6q25.2 SNPs are located between the SCAF8 and CNKSR3 genes, a region with DKD relevant changes in gene expression and an eQTL with IPCEF1, a gene co-translated with CNKSR3. Several other SNPs demonstrated suggestive evidence of association with DKD, within and across populations. These data identify a novel DKD susceptibility locus with consistent directions of effect across diverse ancestral groups and provide insight into the genetic architecture of DKD.

Association of serum lipids with outcomes in Hispanic hemodialysis patients of the West versus East Coasts of the United States.

BACKGROUND: Paradoxical associations exist between serum lipid levels and mortality in patients on maintenance hemodialysis (MHD) including those of Hispanic origin. However, there are significant racial and ethnic variations in patients of 'Hispanic' background. We hypothesized that clinically meaningful differences existed in the association between lipids and survival in Hispanic MHD patients on the West versus East Coast. METHODS: We examined the survival impact of serum lipids in a 2-year cohort of 15,109 MHD patients of Hispanic origin being treated in California, Texas, representing the West versus New York, New Jersey and Florida representing the East Coast, using Cox models with various degrees of adjustments. RESULTS: The association of serum total and HDL cholesterol with mortality follows a U-shaped pattern in Hispanic patients residing in the West. This is in contrast to Hispanic patients in the East Coast whose survival seems to improve with increasing total and HDL cholesterol levels. Elevated serum LDL levels in Hispanic patients on the West Coast are associated with a significant increase in mortality, while this association is not observed in patients residing on the East Coast. CONCLUSIONS: Substantial differences exist in the association of serum lipids with mortality in MHD patients of Hispanic background depending on whether they reside on the West or East Coast of the United States. These geographical variances most likely reflect ethnic, racial and genetic distinctions, which are usually ignored. Future studies should take into account these critical variations in a population of patients who make up a significant portion of our society.

The Chronic Kidney Disease - Colonic Axis.

Chronic kidney disease (CKD) has long been known to cause significant gastrointestinal and colonic pathology. Recent advances in understanding of the role of colonic bacterial microbiome and its function and composition in health and disease have revealed previously unappreciated effects of CKD-associated colonic pathology on the development of uremic complications. CKD can result in profound changes in the microbiome composition and biosynthetic pattern, and the structure and function of the colon. Increases in bacteria that produce urease, uricase, p-cresol- and indole-forming enzymes and the depletion of bacteria that possess short chain fatty acid forming enzymes have been described in human and animal models. Disruption of the colonic epithelial tight junction in different animal models of CKD has been reported and is largely due to the conversion of luminal urea to ammonia by urease possessing bacteria. Together, these changes contribute to the pathogenesis of systemic inflammation and uremic toxicity by allowing the translocation of endotoxin and microbial fragments into the circulation. Additionally, colonic bacteria are the main source of several well-known pro-inflammatory uremic toxins such as indoxyl sulfate, P-cresol sulfate. This review is intended to provide an overview of the effects of CKD on the colonic microbiome and the intestinal epithelial barrier structure and function and their role in the pathogenesis the systemic inflammation and uremic toxicity.

Timing of return to dialysis in patients with failing kidney transplants.

In the last decade, the number of patients starting dialysis after a failed kidney transplant has increased substantially. These patients appear to be different from their transplant-naïve counterparts, and so may be the timing of dialysis therapy initiation. An increasing number of studies suggest that in transplant-naïve patients, later dialysis initiation is associated with better outcomes. Very few data are available on timing of dialysis reinitiation in failed transplant recipients, and they suggest that an earlier return to dialysis therapy tended to be associated with worse survival, especially among healthier and younger patients and women. Failed transplant patients may also have unique issues such as continuation of immunosuppression versus withdrawal or the need for remnant allograft nephrectomy with regard to dialysis reinitiation. These patients may have a different predialysis preparation work-up, worse blood pressure control, higher or lower serum phosphorus levels, lower serum bicarbonate concentration, and worse anemia management. The choice of dialysis modality may also represent an important question for these patients, even though there appears to be no difference in mortality between patients starting peritoneal versus hemodialysis. Finally, failed transplant patients returning to dialysis appear to have a higher mortality rate compared with transplant-naïve incident dialysis patients, especially in the first several months of dialysis therapy. In this review, we will summarize the available data related to the timing of dialysis initiation and outcomes in failed kidney transplant patients after returning to dialysis.

Exposure to potentially toxic hydrocarbons and halocarbons released from the dialyzer and tubing set during hemodialysis.

BACKGROUND: Although much is known about the effect of chronic kidney failure and dialysis on the composition of solutes in plasma, little is known about their impact on the composition of gaseous compounds in exhaled breath. This study was designed to explore the effect of uremia and the hemodialysis (HD) procedure on the composition of exhaled breath. Breath samples were collected from 10 dialysis patients immediately before, during, and after a dialysis session. To determine the potential introduction of gaseous compounds from dialysis components, gasses emitted from dialyzers, tubing set, dialysate, and water supplies were collected. STUDY DESIGN: Prospective cohort study. PARTICIPANTS: 10 HD patients and 10 age-matched healthy individuals. PREDICTOR: Predictors include the dialyzers, tubing set, dialysate, and water supplies before, during, and after dialysis. OUTCOMES: Changes in the composition of exhaled breath. MEASUREMENTS: A 5-column/detector gas chromatography system was used to measure hydrocarbon, halocarbon, oxygenate, and alkyl nitrate compounds. RESULTS: Concentrations of 14 hydrocarbons and halocarbons in patients' breath rapidly increased after the onset of the HD treatment. All 14 compounds and 5 others not found in patients' breath were emitted from the dialyzers and tubing sets. Contrary to earlier reports, exhaled breath ethane concentrations in our dialysis patients were virtually unchanged during the HD treatment. LIMITATIONS: Single-center study with a small sample size may limit the generalizability of the findings. CONCLUSIONS: The study documented the release of several potentially toxic hydrocarbons and halocarbons to patients from the dialyzer and tubing sets during the HD procedure. Because long-term exposure to these compounds may contribute to the morbidity and mortality in dialysis population, this issue should be considered in the manufacturing of the new generation of dialyzers and dialysis tubing sets.

Effect of uremia on structure and function of immune system.

End-stage renal disease (ESRD) is simultaneously associated with immune activation, marked by systemic inflammation, and immune deficiency. Systemic inflammation contributes to atherosclerosis, cardiovascular disease, cachexia, and anemia, whereas immune deficiency leads to impaired response to vaccination, and increased incidence and severity of microbial infections. ESRD-associated inflammation and immune deficiency are associated with the following: (a) general expansion of monocytes and elevations of their basal integrin, Toll-like receptor (TLR)-2, TLR-4 expression, cytokine production, and reactive oxygen species (ROS) generation and reduced phagocytic capacity, (b) depletion and impaired inhibitory activity of regulatory T cells, (c) spontaneous activation, degranulation, increased basal ROS production, decreased phagocytic capacity, and increased apoptosis of the circulating polymorphonuclear leukocytes, (d) upregulation of ROS production machinery and chemokine expression in the cellular constituents of various tissues, highlighting participation of nonimmune cells in the prevailing inflammatory state, (e) depletion of the antigen-presenting dendritic cells, (f) reduced CD4/CD8 T cell ratio and depletion of naïve and central memory T cells, (g) diffuse B cell lymphopenia leading to impaired humoral immunity, and (h) increased proinflammatory activity of low-density lipoprotein and reduced anti-inflammatory capacity of high-density lipoprotein. Thus, ESRD-associated inflammation is due to activation of innate immune system, orchestrated by monocytes, macrophages, granulocytes, and cellular constituents of other organs/tissues. This is coupled with immune deficiency that is caused by depletion of dendritic cells, naïve and central memory T cells and B cells, and impaired phagocytic function of polymorphonuclear leukocytes and monocytes.

Effect of hemodialysis and diet on the exhaled breath methanol concentration in patients with ESRD.

OBJECTIVES: End-stage renal disease (ESRD) causes accumulation of nitrogenous waste products and acid-base, mineral, fluid, and electrolyte disorders, which are partially corrected by hemodialysis (HD). While the effects of ESRD and dialysis on body fluid composition are well known, the effects on composition of expired breath are uncertain. Methanol is produced from unabsorbable complex carbohydrates by the colonic microbiome. Dietary restrictions of fruits and vegetables aimed at limiting potassium intake lower the intake of dietary fibers; the reduced fiber intake can in turn reduce production of methanol and its appearance in the exhaled breath. In this study, we investigated the inter- and intradialytic changes in the breath methanol levels. DESIGN AND METHOD: Ten ESRD patients were studied during HD procedures at 3- and 2-day interdialytic intervals. On each occasion, 20 exhaled breath and room air samples were collected using evacuated canisters. Ten age-matched normal subjects served as controls. The samples were analyzed on a unique 6-column/detector gas chromatography system. RESULTS: Seven ESRD patients consuming renal diet had lower methanol concentration (90 ± 29 ppbv) than the 3 patients consuming high-fiber diet (340 ± 48 ppbv, P ≤ .0006) and the 10 controls consuming unrestricted diets (202 ± 80 ppbv, P ≤ .001). HD significantly lowered breath methanol (60% ± 12%), paralleling the fall in serum urea concentration (70% ± 6%). The predialysis methanol concentration was slightly higher at 3-day than the 2-day interdialytic intervals. CONCLUSION: Dietary restriction of fruits and vegetables lowers methanol production by the gut microbial flora in ESRD patients. Perhaps, methanol is a reliable breath biomarker to monitor individuals' daily fiber intake. Breath methanol is dramatically reduced by HD, reflecting its efficient removal.

Salutary effects of hemodialysis on low-density lipoprotein proinflammatory and high-density lipoprotein anti-inflammatory properties in patient with end-stage renal disease.

End-stage renal disease (ESRD) causes oxidative stress, inflammation, low-density lipoprotein (LDL) oxidation, high-density lipoprotein (HDL) deficiency and accelerated atherosclerosis. Uptake of oxidized LDL by macrophages results in foam cell and plaque formation. HDL mitigates atherosclerosis via reverse cholesterol transport and inhibition of LDL oxidation. ESRD heightens LDL inflammatory activity and suppresses HDL anti-inflammatory activity. The effect of hemodialysis on the LDL and HDL inflammatory properties is unknown. By removing the potential pro-oxidant/proinflammatory uremic toxins, dialysis may attenuate LDL inflammatory and HDL anti-inflammatory properties. Conversely, exposure to dialyzer membrane and tubing and influx of impurities from dialysate can intensify LDL and HDL inflammatory activities. This study examined the effect of hemodialysis on LDL and HDL inflammatory activities. Plasma samples were obtained from 12 normal control and 26 ESRD patients before and after hemodialysis with (16 patients) or without (10 patients) heparinization. HDL and LDL were isolated and tested for monocyte chemotactic activity in cultured endothelial cells. ESRD patients had increased LDL chemotactic activity, reduced HDL anti-inflammatory activity, paraoxonase and glutathione peroxidase levels, and elevated plasma IL-6 before dialysis. Hemodialysis partially improved LDL inflammatory and HDL anti-inflammatory activities and enhanced patients' HDL ability to suppress their LDL inflammatory activity. The salutary effect on LDL inflammatory activity was significantly greater in patients dialyzed with than those without heparin. ESRD heightens LDL inflammatory and impairs HDL anti-inflammatory activities. Hemodialysis partially improves LDL and HDL inflammatory activities. The salutary effects of hemodialysis are in part mediated by heparin, which is known to possess lipolytic and antioxidant properties.

Examination of association with candidate genes for diabetic nephropathy in a Mexican American population.

BACKGROUND AND OBJECTIVES: Diabetic nephropathy (DN) is a multifactorial complication characterized by persistent proteinuria in susceptible individuals with type 1 and type 2 diabetes. Disease burden in people of Mexican-American descent is particularly high, but there are only a few studies that characterize genes for DN in this ethnic group. Two genes, carnosine dipeptidase 1 (CNDP1) and engulfment and cell motility 1 (ELMO1) previously showed association with DN in other ethnic groups. CNDP1 and ELMO1 were examined along with eight other genes that are less well characterized for DN in a new study of Mexican-Americans. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The target sample was patients of Mexican-American ancestry collected from three centers: 455 patients with DN and 437 controls with long-term diabetes but no incident nephropathy. Forty-two, 227, and 401 single nucleotide polymorphisms (SNPs) in CNDP1, ELMO1, and the other eight genes, respectively, were examined. RESULTS: No region in CNDP1 or ELMO1 showed significant P values. Of the other eight candidate genes, an association of DN with a SNP pair, rs2146098 and rs6659783, was found in hemicentin 1 (HMCN1) (unadjusted P = 6.1 x 10(-5)). Association with a rare haplotype in this region was subsequently identified. CONCLUSIONS: The associations in CNDP1 or ELMO1 were not replicable; however, an association of DN with HMCN1 was found. Additional work at this and other loci will enable refinement of the genetic hypotheses regarding DN in the Mexican-American population to find therapies for this debilitating disease.

Upregulation of monocyte/macrophage HGFIN (Gpnmb/Osteoactivin) expression in end-stage renal disease.

BACKGROUND AND OBJECTIVES: Hematopoietic growth factor-inducible neurokinin 1 (HGFIN), also known as Gpnmb and osteoactivin, is a transmembrane glycoprotein that is expressed in numerous cells, including osteoclasts, macrophages, and dendritic cells. It serves as an osteoblast differentiation factor, participates in bone mineralization, and functions as a negative regulator of inflammation in macrophages. Although measurable at low levels in monocytes, monocyte-to-macrophage transformation causes substantial increase in HGFIN expression. HGFIN is involved in systemic inflammation, bone demineralization, and soft tissue vascular calcification. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We explored HGFIN expression in monocytes and monocyte-derived macrophages in 21 stable hemodialysis patients and 22 control subjects. RESULTS: Dialysis patients exhibited marked upregulation of colony-stimulating factor and IL-6 and significant downregulation of IL-10 in intact monocytes and transformed macrophages. HGFIN expression in intact monocytes was negligible in control subjects but conspicuously elevated (8.6-fold) in dialysis patients. As expected, in vitro monocyte-to-macrophage transformation resulted in marked upregulation of HGFIN in cells obtained from both groups but much more so in dialysis patients (17.5-fold higher). Upregulation of HGFIN and inflammatory cytokines in the uremic monocyte-derived macrophages occurred when grown in the presence of either normal or uremic serum, suggesting the enduring effect of the in vivo uremic milieu on monocyte/macrophage phenotype and function. CONCLUSIONS: Uremic macrophages exhibit increased HGFIN gene and protein expression and heightened expression of proinflammatory and a suppressed expression of anti-inflammatory cytokines. Further studies are needed to determine the role of heightened monocyte/macrophage HGFIN expression in the pathogenesis of ESRD-induced inflammation and vascular and soft tissue calcification.

Effect of end-stage renal disease on B-lymphocyte subpopulations, IL-7, BAFF and BAFF receptor expression.

BACKGROUND: End-stage renal disease (ESRD) results in increased susceptibility to infections, impaired response to vaccination and diffuse B-cell lymphopenia. However, the precise nature and mechanism of ESRD-induced B-cell lymphopenia remains unclear. Therefore, we studied the distribution of major B-cell subsets, B-cell growth, differentiation and survival factors, IL-7 and BAFF, and their receptors in 21 haemodialysis patients and 21 controls. METHODS: Innate B1 cells (CD19+, CD5+), conventional B2 cells (CD19+, CD5-), newly formed transitional B cells (CD19+, CD10+, CD27-), naïve B cells (CD19+, CD27-) and memory B cells (CD19+, CD27+) and BAFF receptor were quantified by flow cytometry. Plasma IL-7, BAFF, IL-6, TNF-alpha and IL-10 were measured by ELISA. RESULTS: The ESRD group exhibited significant reductions of all B-cell subpopulations except for transitional B cells that were less severely affected. No significant difference was found in B-cell apoptosis between the ESRD and control groups. Moreover, plasma IL-7 and BAFF levels were elevated in ESRD patients, therefore excluding their deficiencies as a possible culprit. However, BAFF receptor expression was significantly reduced in transitional but not mature B cells in the ESRD group. Interestingly, B-cell activation with the TLR9 agonist resulted in significantly greater production of IL-6 and TNF alpha but not IL-10 in the ESRD group. CONCLUSIONS: Thus, despite elevation of B-cell growth, differentiation and survival factors, ESRD patients exhibited diffuse reduction of B-cell subpopulations. This was associated with the down-regulation of BAFF receptor in transitional B cells. The latter can, in part, contribute to B-cell lymphopenia by promoting resistance to the biological actions of BAFF that is a potent B-cell differentiation and survival factor.

Human uraemic plasma stimulates release of leptin and uptake of tumour necrosis factor-alpha in visceral adipocytes.

BACKGROUND: End-stage renal disease (ESRD) is commonly associated with anorexia, malnutrition and inflammation. In addition to serving as the primary reservoir for energy storage, adipocytes produce numerous pro- and anti-inflammatory mediators and regulate food intake by releasing the appetite-suppressing (leptin) and appetite-stimulating (adiponectin) hormones. Under normal conditions, release of leptin is stimulated by feeding to prevent excess intake, and release of adiponectin is stimulated by fasting to induce feeding. However, under certain pathological conditions such as inflammation, maladaptive release of these hormones leads to anorexia, wasting and malnutrition and simultaneously intensifies inflammation. Anorexia, malnutrition and inflammation in ESRD are frequently accompanied by hyper-leptinaemia. This study was designed to test the hypothesis that uraemic plasma may stimulate leptin release and suppress adiponectin release in normal adipocytes. METHODS: Visceral adipose tissue was harvested from normal rats, and adipocytes were isolated and incubated for 2-4 h in media containing 90% plasma from 12 ESRD patients (before and after haemodialysis) and 12 normal control subjects. RESULTS: The ESRD group had a marked elevation of plasma TNF-alpha, IL-6, IL-8 and leptin concentrations before and after haemodialysis. Incubation in media containing plasma from the ESRD group elicited a much greater leptin release by adipocytes than that containing normal plasma. Post-dialysis plasma evoked an equally intense leptin release. The rise in leptin release was coupled with a parallel fall in TNF-alpha concentration in the incubation media. In contrast to leptin, adiponectin release in the presence of uraemic plasma was similar to that found with the control plasma. CONCLUSIONS: Exposure to uraemic plasma induces exuberant release of leptin that is coupled with avid uptake of TNF-alpha by visceral adipocytes. These observations confirm the role of TNF-alpha, formerly known as cachexin, in the over-production and release of leptin in patients with ESRD.

In vitro stimulation of HDL anti-inflammatory activity and inhibition of LDL pro-inflammatory activity in the plasma of patients with end-stage renal disease by an apoA-1 mimetic peptide.

Features of end-stage renal disease such as oxidative stress, inflammation, hypertension, and dyslipidemia are associated with accelerated atherosclerosis and increased risk of death from cardiovascular disease. By inhibiting the formation and increasing the disposal of oxidized lipids, HDL exerts potent antioxidant and anti-inflammatory actions. Given that apolipoproteinA-1 can limit atherosclerosis, we hypothesized that an apolipoproteinA-1 mimetic peptide, 4F, may reduce the proinflammatory properties of LDL and enhance the anti-inflammatory properties of HDL in uremic plasma. To test this, plasma from each of 12 stable hemodialysis patients and age-matched control subjects was incubated with 4F or vehicle. The isolated HDL and LDL fractions were added to cultured human aortic endothelial cells to quantify monocyte chemotactic activity, thus measuring their pro- or anti-inflammatory index. The LDL from the hemodialysis patients was more pro-inflammatory and their HDL was less anti-inflammatory than those of the control subjects. Pre-incubation of the plasma from the hemodialysis patients with 4F decreased LDL pro-inflammatory activity and enhanced HDL anti-inflammatory activity. Whether 4F or other apolipoproteinA-1 mimetic peptides will have any therapeutic benefit in end-stage renal disease will have to be examined directly in clinical studies.

Antioxidant therapy does not ameliorate oxidative stress and inflammation in patients with end-stage renal disease.

Oxidative stress and inflammation are common manifestations and major mediators of cardiovascular and many other complications of end-stage renal disease (ESRD). Oxidative stress and inflammation are intimately interrelated as each can cause the other. The present study tested the hypothesis that antioxidant therapy may alleviate oxidative stress and improve inflammation in ESRD patients. We studied 37 hemodialysis patients, of whom 20 were treated daily with a combination of vitamin E, 800 lU; vitamin C, 250 mg; vitamin B6, 100 mg; vitamin B12, 250 microg; and folic acid, 10 mg; whereas 17 patients were given placebo for 8 weeks. Predialysis levels of f-2 isoprostane and protein carbonyl (markers of oxidative stress), C-reactive protein (CRP) and IL6 (markers/ mediators of inflammation) were measured prior to and at 4 and 8 weeks after the onset of therapy. Kt/V, predialysis and postdialysis blood pressure, blood hemoglobin, erythropoietin requirement, plasma ferritin and transferrin saturation, and nutritional indexes were similar among the 2 groups at baseline and remained virtually unchanged throughout the study period. Likewise, plasma f-2 isoprostane, protein carbonyl, CRP, and IL-6 levels remained unchanged and were unaffected by antioxidant administration. In conclusion, the addition of a potent antioxidant cocktail to conventional vitamin supplements had no effect on severity of ESRD-induced oxidative stress, inflammation, hypertension, anemia, or nutritional disorders in hemodialysis patients. Thus, high doses of vitamins beyond the routinely prescribed vitamin supplements do not appear to be indicated in this population.

Plasma phospholipid transfer protein, cholesteryl ester transfer protein and lecithin:cholesterol acyltransferase in end-stage renal disease (ESRD).

BACKGROUND: Chronic kidney disease (CKD) results in accelerated atherosclerosis that is primarily caused by inflammation, oxidative stress and impaired triglyceride and HDL metabolisms. Several plasma proteins including phospholipid transfer protein (PTLP), cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyltransferase (LCAT) affect HDL metabolism. PLTP transfers phospholipids and free cholesterol from triglyceride-rich lipoproteins to HDL, phospholipids between HDL particles and facilitates cholesterol efflux from cells. CETP catalyzes the transfer of cholesteryl esters from HDL to LDL in exchange for triglycerides, and LCAT catalyzes esterification of free cholesterol on the surface of HDL. Given the role of these proteins in the regulation of HDL metabolism, we examined the effect of ESRD on plasma PLTL, CETP and LCAT. METHODS: A group of 21 stable ESRD patients maintained on haemodialysis and a group of 21 age-matched normal control individuals were included in the study. Plasma apolipoprotein A-1, PLTP, CETP and LCAT levels were measured. RESULTS: Plasma triglyceride concentration was elevated and plasma HDL cholesterol, apolipoprotein A-1 and LCAT concentrations were significantly reduced, whereas plasma PLTP and CETP concentrations and activities were unchanged in the ESRD patients. CONCLUSIONS: These findings point to acquired LCAT and Apo A-1 deficiencies and tend to exclude dysregulation of PLTP or CETP in the pathogenesis of HDL abnormalities in haemodialysis patients.