Hypercholesterolemia in Progressive Renal Failure Is Associated with Changes in Hepatic Heparan Sulfate - PCSK9 Interaction.

BACKGROUND: Dyslipidemia is an important risk factor in CKD. The liver clears triglyceride-rich lipoproteins (TRL) via LDL receptor (LDLR), LDLR-related protein-1 (LRP-1), and heparan sulfate proteoglycans (HSPGs), mostly syndecan-1. HSPGs also facilitate LDLR degradation by proprotein convertase subtilisin/kexin type 9 (PCSK9). Progressive renal failure affects the structure and activity of hepatic lipoprotein receptors, PCSK9, and plasma cholesterol. METHODS: Uninephrectomy- and aging-induced CKD in normotensive Wistar rats and hypertensive Munich-Wistar-Frömter (MWF) rats. RESULTS: Compared with 22-week-old sex- and strain-matched rats, 48-week-old uninephrectomized Wistar-CKD and MWF-CKD rats showed proteinuria, increased plasma creatinine, and hypercholesterolemia (all P<0.05), which were most apparent in hypertensive MWF-CKD rats. Hepatic PCSK9 expression increased in both CKD groups (P<0.05), with unusual sinusoidal localization, which was not seen in 22-week-old rats. Heparan sulfate (HS) disaccharide analysis, staining with anti-HS mAbs, and mRNA expression of HS polymerase exostosin-1 (Ext-1), revealed elongated HS chains in both CKD groups. Solid-phase competition assays showed that the PCSK9 interaction with heparin-albumin (HS-proteoglycan analogue) was critically dependent on polysaccharide chain length. VLDL binding to HS from CKD livers was reduced (P<0.05). Proteinuria and plasma creatinine strongly associated with plasma cholesterol, PCSK9, and HS changes. CONCLUSIONS: Progressive CKD induces hepatic HS elongation, leading to increased interaction with PCSK9. This might reduce hepatic lipoprotein uptake and thereby induce dyslipidemia in CKD. Therefore, PCSK9/HS may be a novel target to control dyslipidemia.

Sodium thiosulfate improves renal function and oxygenation in L-NNA-induced hypertension in rats.

Sodium thiosulfate, a reversible oxidation product of hydrogen sulfide, has vasodilating and anti-oxidative properties, making it an attractive agent to alleviate damaging effects of hypertension. In experimental settings, inhibition of nitric oxide synthase causes hypertension, renal dysfunction and damage. We hypothesized that thiosulfate would attenuate renal injury and improve renal function, hemodynamics and the efficiency of oxygen utilization for sodium reabsorption in hypertensive renal disease. Additionally, thiosulfate co-administration would further improve these variables when compared to inhibiting the renin-angiotensin system alone. Nitric oxide synthase was inhibited in Sprague Dawley rats by administering N-ω-nitro-L-arginine (L-NNA) in the food for three weeks. After one week, rats were split into two groups; without and with thiosulfate in the drinking water. In a parallel study, rats given N-ω-nitro-L-arginine and the angiotensin converting enzyme inhibitor lisinopril at a relatively low dose in their food were divided into two groups; without and with thiosulfate in the drinking water. Treatment with thiosulfate alleviated hypertension (mean 190 vs. 229 mmHg), lowered plasma urea (mean 11.3 vs. 20.0 mmol/L) and improved the terminal glomerular filtration rate (mean 503 vs. 260 µl/min/100 gbw), effective renal plasma flow (mean 919 vs. 514 µl/min/100 gbw) and oxygen utilization for sodium reabsorption (mean 14.3 vs. 8.6 µmol/µmol). Combining thiosulfate with lisinopril further lowered renal vascular resistance (mean 43 vs. 63 mmHg/ml/min/100 gbw) and prevented glomerulosclerosis. Thus, our results suggest that thiosulfate has therapeutic potential in hypertensive renal disease and might be of value when added to standard antihypertensive therapies.

Complement activation and long-term graft function in ABO-incompatible kidney transplantation.

BACKGROUND: ABO-incompatible and ABO-compatible kidney transplantation are equivalent in terms of short-term graft and patient survival. This is thought to be the result of ABO-incompatible graft accommodation, which occurs when anti-blood group antibodies re-occur after transplantation but somehow do not yield their detrimental effect. The underlying mechanism is unclear, but one of the hypotheses is that this is the result of complement inhibition. Since virtually all ABO-incompatible graft biopsies are C4d positive, this complement inhibition must occur somewhere in the complement cascade after the formation of C4d has already taken place, but where exactly is unclear. It is also unclear whether complement inhibition is complete. Incomplete accommodation could explain why recent studies have shown that long-term graft function in ABO-incompatible transplantation is somewhat inferior to ABO-compatible kidney transplantation. AIM: To unravel the relationship between pre-transplant anti-ABO antibodies, complement activation, and long-term graft function. METHODS: We included all 27 ABO-incompatible transplantations that were performed between 2008 and 2013 at the Academic Medical Center Amsterdam and the University Medical Center Groningen. For each ABO-incompatible transplantation, we included four ABO-compatible controls matched by age, sex, and transplantation date. RESULTS: Graft and patient survival were not significantly different. The slope of kidney function during five-year follow-up was also not significantly different, but ABO-incompatible recipients did have a lower kidney function at three months (creatinine clearance 58 vs 69 mL/min, P = 0.02, Modification of Diet in Renal Disease 46 vs 52 mL/min/1.73 m2, P = 0.08), due to a high rate of early rejection (33% vs 15%, P = 0.03), mostly T-cell mediated. Pre-transplant anti-ABO IgG titers were positively correlated with C5b-9 staining, which itself was positively correlated with the occurrence of T-cell mediated rejection. This may be the result of concurrent C5a formation, which could function as a costimulatory signal for T-cell activation. CONCLUSION: Co-stimulation of T-cell activation by ongoing complement activation by anti-ABO antibodies may be responsible for an impaired long-term graft function in ABO-incompatible kidney transplantation.

Subclinical Changes in Deceased Donor Kidney Proteomes Are Associated With 12-month Allograft Function Posttransplantation-A Preliminary Study.

BACKGROUND: Cerebral injury during donation after brain death may induce systemic damage affecting long-term kidney function posttransplantation. Conventional evaluation of donor organ quality as a triage for transplantation is of limited utility. METHODS: We compared donor kidneys yielding opposing extremes of the continuum of posttransplantation outcomes by several common kidney biopsy evaluation techniques, including Kidney Donor Profile Index and Remuzzi scoring, and analyzed tissue from a minimal sample cohort using label-free quantitation mass spectrometry. Further assessment of the proteomic results was performed by orthogonal quantitative comparisons of selected key proteins by immunoblotting. RESULTS: We show that common evaluation techniques of kidney biopsies were not predictive for posttransplantation outcomes. In contrast, despite the limited cohort size, the proteomic analysis was able to clearly differentiate between kidneys yielding extreme posttransplantation outcome differences. Pathway analysis of the proteomic data suggested that outcome-related variance in protein abundance associated with profibrotic, apoptosis, and antioxidant proteins. Immunoblotting confirmation further supported this observation. CONCLUSIONS: We present preliminary data indicating that there is scope for existing evaluation approaches to be supplemented by the analysis of proteomic differences. Furthermore, the observed outcome-related variance in a limited cohort was supported by immunoblotting and is consistent with mechanisms previously implicated in the development of injury and cytoprotection in kidney transplantation.

[An unexpected pathology report of a sentinel lymph node]. / Onverwachte bevinding in de schildwachtklier.

A 60-year-old woman was treated for breast carcinoma. She underwent a total mastectomy with sentinel node biopsy of her right breast. Pathologic examination of the sentinel lymph node showed an unusual large nodal naevus.

Nonesterified fatty acids and development of graft failure in renal transplant recipients.

BACKGROUND: Chronic transplant dysfunction is the most common cause of graft failure on the long term. Proteinuria is one of the cardinal clinical signs of chronic transplant dysfunction. Albumin-bound fatty acids (FA) have been hypothesized to be instrumental in the etiology of renal damage induced by proteinuria. We therefore questioned whether high circulating FA could be associated with an increased risk for future development of graft failure in renal transplant recipients (RTR). To this end, we prospectively investigated the association of fasting concentrations of circulating nonesterified FA (NEFA) with the development of graft failure in RTR. METHODS: Baseline measurements were performed between 2001 and 2003 in outpatient RTR with a functioning graft of more than 1 year. Follow-up was recorded until May 19, 2009. Graft failure was defined as return to dialysis or retransplantation. RESULTS: We included 461 RTR at a median (interquartile range [IQR]) of 6.1 (3.3-11.3) years after transplantation. Median (IQR) fasting concentrations of NEFA were 373 (270-521) µM/L. Median (IQR) follow-up for graft failure beyond baseline was 7.1 (6.1-7.5) years. Graft failure occurred in 23 (15%), 14 (9%), and 9 (6%) of RTR across increasing gender-specific tertiles of NEFA (P=0.04). In a gender-adjusted Cox-regression analysis, log-transformed NEFA level was inversely associated with the development of graft failure (hazard ratio, 0.61; 95% confidence interval, 0.47-0.81; P<0.001). CONCLUSIONS: In this prospective cohort study in RTR, we found an inverse association between fasting NEFA concentrations and risk for development of graft failure. This association suggests a renoprotective rather than a tubulotoxic effect of NEFA. Further studies on the role of different types of NEFA in the progression of renal disease are warranted.

Are brain and heart tissue prone to the development of thiamine deficiency?

Thiamine deficiency is a continuing problem leading to beriberi and Wernicke's encephalopathy. The symptoms of thiamine deficiency develop in the heart, brain and neuronal tissue. Yet, it is unclear how rapid thiamine deficiency develops and which organs are prone to development of thiamine deficiency. We investigated these issues in a thiamine deficient animal model. Twenty-four male Lewis rats were fed a thiamine deficient diet, which contained 0.04% of normal thiamine intake. Six control rats were fed 200 µg of thiamine per day. Every week a group of six rats on the thiamine-deficient diet was sacrificed and blood, urine and tissue were stored. Blood and tissue transketolase activity, thiamine and thiamine metabolites were measured and PCR of thiamine transporter-1 (ThTr-1) was performed. Transketolase activity was significantly reduced in red blood cells, liver, lung, kidney and spleen tissue after two weeks of thiamine deficient diet. In brain tissue, transketolase activity was not reduced after up to four weeks of thiamine deficient diet. The amount of thiamine pyrophosphate was also significantly conserved in brain and heart tissue (decrease of 31% and 28% respectively), compared to other tissues (decrease of ~70%) after four weeks of thiamine deficient diet. There was no difference between tissues in ThTr-1 expression after four weeks of thiamine deficient diet. Despite the fact that the heart and the brain are predilection sites for complications from thiamine deficiency, these tissues are protected against thiamine deficiency. Other organs could be suffering from thiamine deficiency without resulting in clinical signs of classic thiamine deficiency in beriberi and Wernicke's encephalopathy.

A double-blind, randomized, placebo-controlled clinical trial on benfotiamine treatment in patients with diabetic nephropathy.

OBJECTIVE: To investigate the effect of benfotiamine on urinary albumin excretion (UAE) and the tubular damage marker kidney injury molecule-1 (KIM-1) in patients with type 2 diabetes and nephropathy. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes and UAE equivalent to 15-300 mg/24 h, despite ACE inhibitors (ACE-Is) or angiotensin receptor blockers (ARBs), were randomly assigned to 12 weeks of benfotiamine (900 mg/day) (n = 39) or placebo (n = 43). RESULTS: Compared with placebo, benfotiamine treatment resulted in significant improvement of thiamine status (P < 0.001). Benfotiamine treatment did not significantly decrease 24-h UAE or 24-h KIM-1 excretion. CONCLUSIONS: In patients with type 2 diabetes and nephropathy, high-dose benfotiamine treatment for 12 weeks in addition to ACE-Is or ARBs did not reduce UAE or KIM-1 excretion, despite improvement of thiamine status.

High plasma hemopexin activity is an independent risk factor for late graft failure in renal transplant recipients.

Chronic low-grade inflammation is involved in late renal transplant dysfunction. Recent studies suggest a role for hemopexin, an acute phase protein, in kidney damage. We investigated whether hemopexin activity (Hx) predicts graft failure in renal transplant recipients (RTRs). In 557 RTRs with functioning grafts for >or=1 year, Hx was measured in citrate-plasma. RTRs were divided according to Hx into two groups; A: sextile 1-5 (464 RTRs, 83%) and B: sextile 6 (92 RTRs, 17%). Hx [median (IQR) 11.1 (3.3-19.1) arbitrary units] was measured at 6.0 (2.6-11.5) years post-transplant. RTRs with high Hx (group B) had significantly higher urinary protein excretion (UP) and diastolic blood pressure than group A, despite significantly more prevalent use of renin-angiotensin-aldosterone system inhibitors. After follow-up [4.6 (3.8-5.2) years], incidence of graft failure in group A was 25 (5%) and in group B 14 (15%,P = 0.0009) After adjustment for high-sensitivity C-reactive protein (hsCRP), UP and other potential confounders, Hx remained an independent predictor of graft failure [HR = 2.5 (95% CI 1.2-5.3), P = 0.01]. In conclusion, elevated Hx predicts late graft failure in RTRs, independent of hsCRP and UP. This suggests that Hx measurement, next to measurement of creatinine clearance and UP, could be of value for the identification of RTRs at risk for graft failure.

Tissue thiamine deficiency as potential cause of delayed graft function after kidney transplantation: thiamine supplementation of kidney donors may improve transplantation outcome.

Delayed graft function is an important medical problem after renal transplantation. It occurs in approximately 30% of cases, and is not only associated with more prolonged and complicated hospitalisation, but also with earlier graft loss on the long-term. Delayed graft function is the consequence of acute tubular necrosis caused by ischaemia-reperfusion injury, with insufficiently opposed toxic effects of reactive oxygen species and insufficient ATP regeneration. An optimal tissue thiamine status is pivotal for scavenging of reactive oxygen species and regeneration of ATP. There are several reasons to suppose that tissue thiamine availability is suboptimal in donor kidneys prior to reperfusion in transplantation. These reasons include a high prevalence of untreated thiamine deficiency at admission of donors to intensive care units, quick exhaustion of body thiamine stores during periods of non-feeding or inappropriate feeding during hospital stays of donors, and loss of the water-soluble vitamin into water-based organ preservation solutions. We therefore hypothesize that a suboptimal tissue thiamine status is a cause of delayed graft function after renal transplantation, and that it can be prevented with thiamine supplementation.