Role of CaMKII in diabetes induced vascular injury and its interaction with anti-diabetes therapy.

Diabetes mellitus is a metabolic disorder denoted by chronic hyperglycemia that drives maladaptive structural changes and functional damage to the vasculature. Attenuation of this pathological remodeling of blood vessels remains an unmet target owing to paucity of information on the metabolic signatures of this process. Ca2+/calmodulin-dependent kinase II (CaMKII) is expressed in the vasculature and is implicated in the control of blood vessels homeostasis. Recently, CaMKII has attracted a special attention in view of its chronic upregulated activity in diabetic tissues, yet its role in the diabetic vasculature remains under investigation.This review highlights the physiological and pathological actions of CaMKII in the diabetic vasculature, with focus on the control of the dialogue between endothelial (EC) and vascular smooth muscle cells (VSMC). Activation of CaMKII enhances EC and VSMC proliferation and migration, and increases the production of extracellular matrix which leads to maladaptive remodeling of vessels. This is manifested by activation of genes/proteins implicated in the control of the cell cycle, cytoskeleton organization, proliferation, migration, and inflammation. Endothelial dysfunction is paralleled by impaired nitric oxide signaling, which is also influenced by CaMKII signaling (activation/oxidation). The efficiency of CaMKII inhibitors is currently being tested in animal models, with a focus on the genetic pathways involved in the regulation of CaMKII expression (microRNAs and single nucleotide polymorphisms). Interestingly, studies highlight an interaction between the anti-diabetic drugs and CaMKII expression/activity which requires further investigation. Together, the studies reviewed herein may guide pharmacological approaches to improve health-related outcomes in patients with diabetes.

Gender, age and nationality differences in chronic kidney disease prevalence in the emirate of Abu Dhabi, UAE.

AIM: We aimed to better understand the prevalence of chronic kidney disease in Abu Dhabi, UAE, where a very diverse ethnic population lives, each with their own risk profile. METHODS: Data were analysed on all patients who were tested for serum creatinine in December 2019 for 4 years within our healthcare network. We analysed data for kidney disease by age, gender and nationality to study differences in prevalence and risk. RESULTS: The entire cohort (EC) consisted 1 925 672 samples from 703 122 patients. 24% of patients had GFR < 90 mL/min/1.73 m2 (CKD2-5), 4% had more severe kidney dysfunction (CKD3-5) and 2% had UACR >3 mg/mmol and with GFR > 90 (CKD1). The long follow-up (LFU) group comprised 45.6% of patients who had eGFR on at least two occasions more than 90 days apart, and of these 19.5% had sustained eGFR <90, and 5.2% had CKD3-5. Males had lower eGFR than females in the EC (RR 1.68) and the LFU group (RR 1.76). Emirati Females had the lowest prevalence in the EC (2.9%) and expatriate females in the LFU (3.5%) groups. The relative risks of CKD in expatriate males were highest in the EC (2.14) and the LFU (2.39) groups. When we looked at the age distribution by nationality there were highly significant differences in some populations being highly represented at younger ages. CONCLUSION: The prevalence of kidney disease in Abu Dhabi has a male predominance, with younger expatriates highly represented. A targeted strategy to identify those at high risk may identify early CKD to prevent progression to end-stage kidney disease.

Effect of the phosphate binder sucroferric oxyhydroxide in dialysis patients on endogenous calciprotein particles, inflammation, and vascular cells.

BACKGROUND: Calciprotein particles (CPPs), colloidal mineral-protein nanoparticles, have emerged as potential mediators of phosphate toxicity in dialysis patients, with putative links to vascular calcification, endothelial dysfunction and inflammation. We hypothesized that phosphate binder therapy with sucroferric oxyhydroxide (SO) would reduce endogenous CPP levels and attenuate pro-calcific and pro-inflammatory effects of patient serum towards human vascular cells in vitro. METHODS: This secondary analysis of a randomised controlled crossover study compared the effect of 2-week phosphate binder washout with high-dose (2000 mg/day) and low-dose (250 mg/day) SO therapy in 28 haemodialysis patients on serum CPP levels, inflammatory cytokine/chemokine arrays and human aortic smooth muscle cell (HASMC) and coronary artery endothelial cell (HCAEC) bioassays. RESULTS: In our cohort (75% male, 62 ± 12 years) high-dose SO reduced primary (amorphous) and secondary (crystalline) CPP levels {-62% [95% confidence interval (CI) -76 to -44], P < .0001 and -38% [-62 to -0.14], P < .001, respectively} compared with washout. Nine of 14 plasma cytokines/chemokines significantly decreased with high-dose SO, with consistent reductions in interleukin-6 (IL-6) and IL-8. Exposure of HASMC and HCAEC cultures to serum of SO-treated patients reduced calcification and markers of activation (IL-6, IL-8 and vascular cell adhesion protein 1) compared with washout. Serum-induced HASMC calcification and HCAEC activation was ameliorated by removal of the CPP-containing fraction from patient sera. Effects of CPP removal were confirmed in an independent cohort of chronic kidney disease patients. CONCLUSIONS: High-dose SO reduced endogenous CPP formation in dialysis patients and yielded serum with attenuated pro-calcific and inflammatory effects in vitro.

Effect of lanthanum carbonate on serum calciprotein particles in patients with stage 3-4 CKD-results from a placebo-controlled randomized trial.

BACKGROUND: Calciprotein particles (CPP) are colloidal aggregates of calcium phosphate and the mineral-binding protein fetuin-A, and are potential mediators of cardiovascular disease in chronic kidney disease (CKD). Emerging evidence suggests non-calcium-containing phosphate binders may reduce serum CPP in patients with kidney failure who require dialysis; however, it is unclear whether similar interventions are effective in patients with earlier stages of CKD. METHODS: The IMpact of Phosphate Reduction On Vascular End-points in CKD (IMPROVE-CKD) was a multi-centre, placebo-controlled, randomized trial of lanthanum carbonate on cardiovascular markers in 278 participants with stage 3b/4 CKD. In this pre-specified exploratory analysis, primary (CPP-I) and secondary CPP (CPP-II) were measured in a sub-cohort of participants over 96 weeks. Treatment groups were compared using linear mixed-effects models and the relationship between serum CPP and pulse wave velocity (PWV) and abdominal aortic calcification (AAC) was examined. RESULTS: A total of 253 participants had CPP data for baseline and at least one follow-up timepoint and were included in this analysis. The mean age was 62.4 ± 12.6 years, 32.0% were female and the mean estimated glomerular filtration rate (eGFR) was 26.6 ± 8.3 mL/min/1.73 m2. Baseline median serum CPP-I was 14.9 × 104 particles/mL [interquartile range (IQR) 4.6-49.3] and median CPP-II was 3.3 × 103 particles/mL (IQR 1.4-5.4). There was no significant difference between treatment groups at 96 weeks in CPP-I [22.8% (95% confidence interval -39.2, 36.4), P = 0.65] or CPP-II [-18.3% (95% confidence interval -40.0, 11.2), P = 0.20] compared with a placebo. Serum CPP were not correlated with baseline PWV or AAC, or with the progression of either marker. CONCLUSIONS: Lanthanum carbonate was not associated with a reduction of CPP at 96 weeks when compared with a placebo in a CKD cohort.

Dominant protection from HLA-linked autoimmunity by antigen-specific regulatory T cells.

Susceptibility and protection against human autoimmune diseases, including type I diabetes, multiple sclerosis, and Goodpasture disease, is associated with particular human leukocyte antigen (HLA) alleles. However, the mechanisms underpinning such HLA-mediated effects on self-tolerance remain unclear. Here we investigate the molecular mechanism of Goodpasture disease, an HLA-linked autoimmune renal disorder characterized by an immunodominant CD4+ T-cell self-epitope derived from the α3 chain of type IV collagen (α3135-145). While HLA-DR15 confers a markedly increased disease risk, the protective HLA-DR1 allele is dominantly protective in trans with HLA-DR15 (ref. 2). We show that autoreactive α3135-145-specific T cells expand in patients with Goodpasture disease and, in α3135-145-immunized HLA-DR15 transgenic mice, α3135-145-specific T cells infiltrate the kidney and mice develop Goodpasture disease. HLA-DR15 and HLA-DR1 exhibit distinct peptide repertoires and binding preferences and present the α3135-145 epitope in different binding registers. HLA-DR15-α3135-145 tetramer+ T cells in HLA-DR15 transgenic mice exhibit a conventional T-cell phenotype (Tconv) that secretes pro-inflammatory cytokines. In contrast, HLA-DR1-α3135-145 tetramer+ T cells in HLA-DR1 and HLA-DR15/DR1 transgenic mice are predominantly CD4+Foxp3+ regulatory T cells (Treg cells) expressing tolerogenic cytokines. HLA-DR1-induced Treg cells confer resistance to disease in HLA-DR15/DR1 transgenic mice. HLA-DR15+ and HLA-DR1+ healthy human donors display altered α3135-145-specific T-cell antigen receptor usage, HLA-DR15-α3135-145 tetramer+ Foxp3- Tconv and HLA-DR1-α3135-145 tetramer+ Foxp3+CD25hiCD127lo Treg dominant phenotypes. Moreover, patients with Goodpasture disease display a clonally expanded α3135-145-specific CD4+ T-cell repertoire. Accordingly, we provide a mechanistic basis for the dominantly protective effect of HLA in autoimmune disease, whereby HLA polymorphism shapes the relative abundance of self-epitope specific Treg cells that leads to protection or causation of autoimmunity.

Serum Calciprotein Monomers and Chronic Kidney Disease Progression.

INTRODUCTION: Elevated levels of fibroblast growth factor-23 (FGF23) in chronic kidney disease (CKD) are associated with progression of CKD. FGF23 inhibits proximal tubular phosphate reabsorption, raising phosphate concentrations in the tubular fluid of functioning nephrons, predisposing to spontaneous precipitation of calcium phosphate crystals and resultant tubular injury. Calciprotein monomers (CPM) form spontaneously in biological fluids when clusters of calcium phosphate ions are bound by the liver-derived glycoprotein fetuin-A. Serum CPM are elevated in CKD and are postulated to trigger FGF23 secretion. CPM are also readily filtered at the glomerulus into the tubular fluid, suggesting that higher CPM levels could be associated with progression of CKD via FGF23-mediated increased phosphate load but also through direct effects in the proximal tubule. METHODS: ACADEMIC was a prospective observational study of 200 stable outpatients with CKD stages 3 and 4. Participants were followed until commencement of dialysis or death. In this study, we examined a sub-cohort of 189 participants who had baseline serum available for measurement of CPM. Cox proportionate hazard regression models were used to examine the association between CPM and a composite kidney disease outcome (commencement of dialysis or reduction in estimated glomerular filtration rate [eGFR] >30%). Linear regression models were used to examine the association between CPM and annualized eGFR slope. RESULTS: Relative to the lowest tertile, the highest tertile of CPM was associated with increased risk of the composite kidney disease outcome in univariate models and after sequential adjustment for conventional risk factors for progression of CKD (adjusted hazard ratio 4.22; 95% confidence interval [CI] 1.91, 9.33, p < 0.001). Natural log-transformed CPM was also inversely associated with eGFR slope in univariate and multivariate adjusted models (adjusted ß-coefficient -1.66, 95% CI: -3.10, -0.22, p = 0.024). In exploratory mediation analysis, the association between serum CPM and eGFR slope was partially mediated by iFGF23; however, the majority of the association was direct and independent of the iFGF23 pathway. CONCLUSION: Elevated levels of CPM are associated with the progression of CKD. This association was partially mediated via FGF23, consistent with recent evidence that FGF23 predisposes to spontaneous precipitation of calcium phosphate crystals leading to tubular injury. However, serum CPM also appeared to have a direct association with eGFR slope, raising the possibility that CPM may also be associated with progression of CKD through additional pathways.

Relationship Between Urinary Phosphate and All-Cause and Cardiovascular Mortality in a National Population-Based Longitudinal Cohort Study.

OBJECTIVES: High dietary phosphate intake may lead to adverse outcomes including cardiovascular disease (CVD). Urinary phosphate excretion, a marker of intestinal phosphate absorption, may be a more reliable marker of phosphate homeostasis in steady state than serum phosphate. Studies report good agreement between urine phosphate-to-creatinine ratio (uPiCr) and 24-hour urinary phosphate; however, whether uPiCr is associated with increased risk of CVD or mortality remains uncertain. This study aimed to assess the relationship between uPiCr and all-cause and CVD mortality. DESIGN AND METHODS: This is an observational longitudinal cohort study using data from the population-based national Australian Diabetes, Obesity and Lifestyle study (n = 10,014 participants). Non-linear association between uPiCr and all-cause and CVD mortality was assessed using fractional polynomial transformations. Cox proportional hazards regression models were used to estimate adjusted hazard ratios for all-cause and CVD mortality. RESULTS: Median age [interquartile range] was 50 [41-62] years, and 46% were male. Median uPiCr was 1.38 [1.02-1.79] mmol/mmol. Median follow-up time was 16.9 years with 1,735 deaths. uPiCr was associated with all-cause and CVD mortality in univariate models and when adjusted for age and gender. However, associations were not significant in multivariate models. Sensitivity analyses excluding participants with chronic kidney disease (CKD) revealed a significant J-shaped association between uPiCr and all-cause mortality. Urine phosphate alone showed an association with increased all-cause mortality in a similar J-shape relationship. CONCLUSION: Although no association between uPiCr and all-cause and CVD mortality was observed in multivariate analyses in the whole cohort, a significant relationship between uPiCr and mortality in those without CKD suggests that uPiCr may have predictive validity for future adverse outcomes in people with no CKD.

The effect of increasing dialysate magnesium on calciprotein particles, inflammation and bone markers: post hoc analysis from a randomized controlled clinical trial.

BACKGROUND: The formation of calciprotein particles (CPPs) may be an important component of the humoral defences against ectopic calcification. Although magnesium (Mg) has been shown to delay the transition of amorphous calcium-/phosphate-containing primary CPP (CPP-1) to crystalline apatite-containing secondary CPP (CPP-2) ex vivo, effects on the endogenous CPP pool are unknown. METHODS: We used post hoc analyses from a randomized double-blind parallel-group controlled clinical trial of 28 days treatment with high dialysate Mg of 2.0 mEq/L versus standard dialysate Mg of 1.0 mEq/L in 57 subjects undergoing maintenance hemodialysis for end-stage kidney disease. CPP load, markers of systemic inflammation and bone turnover were measured at baseline and follow-up. RESULTS: After 28 days of treatment with high dialysate Mg, serum total CPP (-52%), CPP-1 (-42%) and CPP-2 (-68%) were lower in the high Mg group (all P < 0.001) but were unchanged in the standard dialysate Mg group. Tumour necrosis factor-α (-20%) and interleukin-6 (-22%) were also reduced with high dialysate Mg treatment (both P < 0.01). High dialysate Mg resulted in higher levels of bone-specific alkaline phosphatase (a marker of bone formation) (+17%) but lower levels of tartrate-resistant acid phosphatase 5 b (a marker of bone resorption; -33%) (both P < 0.01). Inflammatory cytokines and bone turnover markers were unchanged in the standard dialysate Mg group over the same period. CONCLUSIONS: In this exploratory analysis, increasing dialysate Mg was associated with reduced CPP load and systemic inflammation and divergent changes in markers of bone formation and resorption.

Hepatitis B related dilemmas in the renal unit.

Testing for hepatitis B in dialysis patients is routine, but newer and more sensitive detection methods mean that there is sometimes confusion around viral loads and occult infection. There are frequently difficult choices surrounding isolation and treatment. Here we describe the use of HBV serology and DNA testing in decisions around patients with end-stage renal disease. We also suggest isolation decisions based on our current understanding of the virus and its infectivity.

A Randomized Trial on the Effect of Phosphate Reduction on Vascular End Points in CKD (IMPROVE-CKD).

BACKGROUND: Hyperphosphatemia is associated with increased fibroblast growth factor 23 (FGF23), arterial calcification, and cardiovascular mortality. Effects of phosphate-lowering medication on vascular calcification and arterial stiffness in CKD remain uncertain. METHODS: To assess the effects of non-calcium-based phosphate binders on intermediate cardiovascular markers, we conducted a multicenter, double-blind trial, randomizing 278 participants with stage 3b or 4 CKD and serum phosphate >1.00 mmol/L (3.10 mg/dl) to 500 mg lanthanum carbonate or matched placebo thrice daily for 96 weeks. We analyzed the primary outcome, carotid-femoral pulse wave velocity, using a linear mixed effects model for repeated measures. Secondary outcomes included abdominal aortic calcification and serum and urine markers of mineral metabolism. RESULTS: A total of 138 participants received lanthanum and 140 received placebo (mean age 63.1 years; 69% male, 64% White). Mean eGFR was 26.6 ml/min per 1.73 m2; 45% of participants had diabetes and 32% had cardiovascular disease. Mean serum phosphate was 1.25 mmol/L (3.87 mg/dl), mean pulse wave velocity was 10.8 m/s, and 81.3% had abdominal aortic calcification at baseline. At 96 weeks, pulse wave velocity did not differ significantly between groups, nor did abdominal aortic calcification, serum phosphate, parathyroid hormone, FGF23, and 24-hour urinary phosphate. Serious adverse events occurred in 63 (46%) participants prescribed lanthanum and 66 (47%) prescribed placebo. Although recruitment to target was not achieved, additional analysis suggested this was unlikely to have significantly affected the principle findings. CONCLUSIONS: In patients with stage 3b/4 CKD, treatment with lanthanum over 96 weeks did not affect arterial stiffness or aortic calcification compared with placebo. These findings do not support the role of intestinal phosphate binders to reduce cardiovascular risk in patients with CKD who have normophosphatemia. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Australian Clinical Trials Registry, ACTRN12610000650099.

The potential role of antibodies against minor blood group antigens in renal transplantation.

Blood group antigens are red blood cell (RBC) surface markers comprising specific carbohydrate moieties attached to the glycolipids and glycoproteins within the membrane. In addition to the major ABO blood group antigens, at least 35 minor blood group antigens have been defined to date. These antigens have immunogenic potential and may cause a transfusion reaction. There is evidence for renal expression of antigens from the Kidd, MNS, Duffy and Lewis groups and therefore the potential for antibodies directed against these antigens to cross-react in a transplanted kidney. In individuals lacking a specific RBC antigen, antibodies may develop after de novo exposure to that antigen, in addition to the potential presence of pre-existing innate antibodies. Relatively little attention has been paid to non-ABO system antibodies, with most reports in the literature focusing on transfusion reactions rather than on any putative role in allograft rejection. Here, we review each of these antigens in the context of renal transplantation and what limited evidence there is on how such immunological risk may be assessed and managed.

αKlotho-FGF23 interactions and their role in kidney disease: a molecular insight.

Following the serendipitous discovery of the ageing suppressor, αKlotho (αKl), several decades ago, a growing body of evidence has defined a pivotal role for its various forms in multiple aspects of vertebrate physiology and pathology. The transmembrane form of αKl serves as a co-receptor for the osteocyte-derived mineral regulator, fibroblast growth factor (FGF)23, principally in the renal tubules. However, compelling data also suggest that circulating soluble forms of αKl, derived from the same source, may have independent homeostatic functions either as a hormone, glycan-cleaving enzyme or lectin. Chronic kidney disease (CKD) is of particular interest as disruption of the FGF23-αKl axis is an early and common feature of disease manifesting in markedly deficient αKl expression, but FGF23 excess. Here we critically discuss recent findings in αKl biology that conflict with the view that soluble αKl has substantive functions independent of FGF23 signalling. Although the issue of whether soluble αKl can act without FGF23 has yet to be resolved, we explore the potential significance of these contrary findings in the context of CKD and highlight how this endocrine pathway represents a promising target for novel anti-ageing therapeutics.

Monitoring skin temperature at the wrist in hospitalised patients may assist in the detection of infection.

BACKGROUND: Measuring temperature has always been a key observation in the diagnosis of infection. No studies have examined the usefulness of measuring temperature at the wrist to detect infection. AIM: We sought to determine whether a watch measuring wrist temperature could accurately identify patients who are infected. METHODS: Prospective cross-sectional pilot study of temperature monitoring in an unselected patients in a tertiary referral adult nephrology unit. RESULTS: One hundred and four data recording sessions revealed 88 useful data sets, with recording failures in the others. Patients were retrospectively classified as having no infection (Group A, n = 60), clinically diagnosed infection with less than 24 h of treatment with antibiotics (Group B, n = 5), and clinically diagnosed infection with greater than 24 h on antibiotics (Group C, n = 23). There was a significantly higher average maximum temperature in Group B (mean (SEM)) 38°C (0.6) compared with Groups A (36.1°C (0.1)) and C (36.3°C (0.3)). Based on receiver operating characteristics (ROC) a cut-off temperature of ≥37.5°C gave sensitivity 80% and specificity 98%. Mean electrodermal activity was significantly higher in Groups B and C. CONCLUSIONS: ROC of peripheral skin temperature measurements suggest that such a device may identify many patients requiring treatment for infection. This proof of principle study showed value in using a wearable device in the detection of infection and its potential as an early warning or monitoring device.

Vascular calcification in skin and subcutaneous tissue in patients with chronic and end-stage kidney disease.

BACKGROUND: Vascular calcification (VC) is well described in large- and medium-sized vessels in patients with chronic kidney disease (CKD), especially in those with end-stage kidney disease (ESKD) on dialysis. Medial calcification is particularly prevalent in this population and contributes to arterial stiffness and increased cardiovascular mortality and morbidity. Apart from in the setting of calciphylaxis, few studies have assessed skin and subcutaneous calcification and associations with abnormalities of bone and mineral metabolism in patients with CKD. METHODS: We performed a single-centre observational study to evaluate incisional skin tissue samples from three anatomical sites in patients with different stages of CKD undergoing elective surgery. We compared these samples to skin samples of a control cohort without CKD. Staining for calcification was performed with von Kossa method. A subgroup of skin samples were assessed by RT-PCR for upregulation of pro-calcific gene transcripts for tissue non-specific alkaline phosphatase (TNAP) and Runt-related transcription factor 2 (RUNX2). RESULTS: Forty-five patients were evaluated, 34 with CKD (including ESKD) and 11 control patients. VC was identified in 15 skin samples (13 CKD/ESKD and 2 controls). VC was present in the dermal and subcutaneous tissues of the neck, abdomen and arm samples. Two different histological types of VC were identified: speckled medial calcification and internal elastic lamina calcification. Presence of perieccrine calcification was identified in 14 samples, 10 with concurrent VC. There were no significant differences in serum parathyroid hormone, phosphate or calcium in patients with or without VC. Expression of TNAP or RUNX2 was not increased in samples from patients with ESKD or those with histological evidence of calcification. CONCLUSION: This study reports the novel finding of dermal and subcutaneous calcification in multiple anatomical locations in 38% of patients with advanced CKD/ESKD undergoing elective surgery but free from calciphylaxis.

Noninfectious mixed cryoglobulinaemic glomerulonephritis and monoclonal gammopathy of undetermined significance: a coincidental association?

BACKGROUND: Cryoglobulins are cold-precipitable immunoglobulins that may cause systemic vasculitis including cryoglobulinaemic glomerulonephritis (CGN). Type 1 cryoglobulins consist of isolated monoclonal immunoglobulin (mIg), whereas mixed cryoglobulins are typically immune complexes comprising either monoclonal (type 2) or polyclonal (type 3) Ig with rheumatoid activity against polyclonal IgG. Only CGN related to type 1 cryoglobulins has been clearly associated with monoclonal gammopathy of undetermined significance (MGUS) using the conventional serum-, urine- or tissue-based methods of paraprotein detection. CASE PRESENTATION: We present four patients with noninfectious mixed (type 2 or 3) CGN and MGUS. Two patients had type 2 cryoglobulinaemia, one had type 3 cryoglobulinaemia, and one lacked definitive typing of the serum cryoprecipitate. The serum monoclonal band was IgM-κ in all four cases. Treatments included corticosteroids, cyclophosphamide, plasma exchange, and rituximab. At median 3.5 years' follow-up, no patient had developed a haematological malignancy or advanced chronic kidney disease. Other potential causes of mixed cryoglobulinaemia were also present in our cohort, notably primary Sjögren's syndrome in three cases. CONCLUSION: Our study raises questions regarding the current designation of type 2 CGN as a monoclonal gammopathy of renal significance, and the role of clonally directed therapies for noninfectious mixed CGN outside the setting of haematological malignancy.

Profiling histone modifications in the normal mouse kidney and after unilateral ureteric obstruction.

Posttranslational modification of nucleosomal histones is a major determinant of chromatin structure and gene activity. In the present study, we hypothesized that unilateral ureteric obstruction (UUO), a widely used model of tubulointerstitial injury, would be associated with a distinct pattern of histone modifications (marks) in the kidney. Mass spectrometry was used to profile 63 different histone marks in normal mouse kidneys and those after 10 days of UUO. A subsequent histochemical analysis further examined examples of specific marks that changed significantly after UUO for which antisera are available. Histone marks were much more widely distributed and abundant in the normal kidney than is usually appreciated. Although aggregate analysis of the mass spectrometry results revealed net differences between control and UUO groups, residue-specific variations were subtle. Of the 16/63 significant changes (P < 0.05), only 8 changes were quantitatively different by >5%. Nevertheless, we identified several that are not usually examined in the kidney, including marks in the globular domain of core histones (H3:K79), linker histones (H1.4), and histone variants (H3.1:K27 and H3.3:K27). In several cases, there were complementary changes in different marks on the same amino acid. Using H3:K79ME2 as an example, mark enrichment was heterogeneous but largely colocalized with active transcription in a subset of tubular pathology. In conclusion, our study highlights the importance of unbiased screening in examining histone marks. Simultaneous changes in multiple marks on the same amino acid indicate a coordinated histone mark signature. The heterogeneous enrichment of marks, even within the same tubule, highlights the importance of regulatory context.

Outcomes of cinacalcet withdrawal in Australian dialysis patients.

BACKGROUND: Secondary hyperparathyroidism (SHPT) in chronic kidney disease is associated with cardiovascular and bone pathology. Measures to achieve parathyroid hormone (PTH) target values and control biochemical abnormalities associated with SHPT require complex therapies, and severe SHPT often requires parathyroidectomy or the calcimimetic cinacalcet. In Australia, cinacalcet was publicly funded for dialysis patients from 2009 to 2015 when funding was withdrawn following publication of the EVOLVE study, which resulted in most patients on cinacalcet ceasing therapy. We examined the clinical and biochemical outcomes associated with this change at Australian renal centres. AIM: To assess changes to biochemical and clinical outcomes in dialysis patients following cessation of cinacalcet. METHODS: We conducted a retrospective study of dialysis patients who ceased cinacalcet after August 2015 in 11 Australian units. Clinical outcomes and changes in biochemical parameters were assessed over a 24- and 12-month period, respectively, from cessation of cinacalcet. RESULTS: A total of 228 patients was included (17.7% of all dialysis patients from the units). Patients were aged 63 ± 15 years with 182 patients on haemodialysis and 46 on peritoneal dialysis. Over 24 months following cessation of cinacalcet, we observed 26 parathyroidectomies, 3 episodes of calciphylaxis, 8 fractures and 50 deaths. Eight patients recommenced cinacalcet, meeting criteria under a special access scheme. Biochemical changes from baseline to 12 months after cessation included increased levels of serum PTH from 54 (interquartile range 27-90) pmol/L to 85 (interquartile range 41-139) pmol/L (P < 0.0001), serum calcium from 2.3 ± 0.2 mmol/L to 2.5 ± 0.1 mmol/L (P < 0.0001) and alkaline phosphatase from 123 (92-176) IU/L to 143 (102-197) IU/L (P < 0.0001). CONCLUSION: Significant increases in serum PTH, calcium and alkaline phosphatase occurred over a 12-month period following withdrawal of cinacalcet. Longer-term follow up will determine if these biochemical and therapeutic changes are associated with altered rates of parathyroidectomies and cardiovascular mortality and morbidity.

Green dialysis survey: Establishing a baseline for environmental sustainability across dialysis facilities in Victoria, Australia.

AIM: The Green Dialysis Survey aimed to (i) establish a baseline for environmental sustainability (ES) across Victorian dialysis facilities; and (ii) guide future initiatives to reduce the environmental impact of dialysis delivery. METHODS: Nurse unit managers of all Victorian public dialysis facilities received an online link to the survey, which asked 107 questions relevant to the ES of dialysis services. RESULTS: Responses were received from 71/83 dialysis facilities in Victoria (86%), representing 628/660 dialysis chairs (95%). Low energy lighting was present in 13 facilities (18%), 18 (25%) recycled reverse osmosis water and seven (10%) reported use of renewable energy. Fifty-six facilities (79%) performed comingled recycling but only 27 (38%) recycled polyvinyl chloride plastic. A minority educated staff in appropriate waste management (n = 30;42%) or formally audited waste generation and segregation (n = 19;27%). Forty-four (62%) provided secure bicycle parking but only 33 (46%) provided shower and changing facilities. There was limited use of tele- or video-conferencing to replace staff meetings (n = 19;27%) or patient clinic visits (n = 13;18%). A minority considered ES in procurement decisions (n = 28;39%) and there was minimal preparedness to cope with climate change. Only 39 services (49%) confirmed an ES policy and few had ever formed a green group (n = 14; 20%) or were currently undertaking a green project (n = 8;11%). Only 15 facilities (21%) made formal efforts to raise awareness of ES. CONCLUSION: This survey provides a baseline for practices that potentially impact the environmental sustainability of dialysis units in Victoria, Australia. It also identifies achievable targets for attention.

Deterioration of Cortical Bone Microarchitecture: Critical Component of Renal Osteodystrophy Evaluation.

BACKGROUND: Cortical bone is a significant determinant of bone strength and its deterioration contributes to bone fragility. Thin cortices and increased cortical porosity have been noted in patients with chronic kidney disease (CKD), but the "Turnover Mineralization Volume" classification of renal osteodystrophy does not emphasize cortical bone as a key parameter. We aimed to assess trabecular and cortical bone microarchitecture by histomorphometry and micro-CT in patients with CKD G5 and 5D (dialysis). METHODS: Transiliac bone biopsies were performed in 14 patients undergoing kidney transplantation (n = 12) and parathyroidectomy (n = 2). Structural parameters were analysed by histomorphometry and micro-CT including trabecular bone volume, thickness (TbTh), number (TbN) and separation and cortical thickness (CtTh) and porosity (CtPo). Indices of bone remodelling and mineralisation were obtained and relationships to bone biomarkers examined. Associations were determined by Spearman's or Pearson's rank correlation coefficients. RESULTS: By micro-CT, trabecular parameters were within normal ranges in most patients, but all patients showed very low CtTh (127 ± 44 µm) and high CtPo (60.3 ± 22.5%). CtPo was inversely related to TbN (r = -0.56; p = 0.03) by micro-CT and to TbTh (r = -0.60; p = 0.024) by histomorphometry and correlated to parathyroid hormone values (r = 0.62; p = 0.021). By histomorphometry, bone turnover was high in 50%, low in 21% and normal in 29%, while 36% showed abnormal patterns of mineralization. Significant positive associations were observed between osteoblast surface, osteoclast surface, mineralization surface and bone turnover markers. CONCLUSIONS: Deterioration of cortical -microarchitecture despite predominantly normal trabecular parameters reinforces the importance of comprehensive cortical evaluation in patients with CKD.