Recommendations for culturally safe clinical kidney care for First Nations Australians: a guideline summary.

INTRODUCTION: First Nations Australians display remarkable strength and resilience despite the intergenerational impacts of ongoing colonisation. The continuing disadvantage is evident in the higher incidence, prevalence, morbidity and mortality of chronic kidney disease (CKD) among First Nations Australians. Nationwide community consultation (Kidney Health Australia, Yarning Kidneys, and Lowitja Institute, Catching Some Air) identified priority issues for guideline development. These guidelines uniquely prioritised the knowledge of the community, alongside relevant evidence using an adapted GRADE Evidence to Decision framework to develop specific recommendations for the management of CKD among First Nations Australians. MAIN RECOMMENDATIONS: These guidelines explicitly state that health systems have to measure, monitor and evaluate institutional racism and link it to cultural safety training, as well as increase community and family involvement in clinical care and equitable transport and accommodation. The guidelines recommend earlier CKD screening criteria (age ≥ 18 years) and referral to specialists services with earlier criteria of kidney function (eg, estimated glomerular filtration rate [eGFR], ≤ 45 mL/min/1.73 m2 , and a sustained decrease in eGFR, > 10 mL/min/1.73 m2 per year) compared with the general population. CHANGES IN MANAGEMENT AS RESULT OF THE GUIDELINES: Our recommendations prioritise health care service delivery changes to address institutional racism and ensure meaningful cultural safety training. Earlier detection of CKD and referral to nephrologists for First Nations Australians has been recommended to ensure timely implementation to preserve kidney function given the excess burden of disease. Finally, the importance of community with the recognition of involvement in all aspects and stages of treatment together with increased access to care on Country, particularly in rural and remote locations, including dialysis services.

Muscle fiber type-specific autophagy responses following an overnight fast and mixed meal ingestion in human skeletal muscle.

The aim of the present study was to investigate the fiber type-specific abundance of autophagy-related proteins after an overnight fast and following ingestion of a mixed meal in human skeletal muscle. Twelve overweight, healthy young male volunteers underwent a 3-h mixed meal tolerance test following an overnight fast. Blood samples were collected in the overnight-fasted state and throughout the 180-min postmeal period. Skeletal muscle biopsies were collected in the fasted state, and at 30 and 90 min after meal ingestion. Protein content of key autophagy markers and upstream signaling responses were measured in whole muscle and pooled single fibers using immunoblotting. In the fasted state, type I fibers displayed lower LC3B-I but higher LC3B-II abundance and higher LC3B-II/LC3B-I ratio compared with type II fibers (P < 0.05). However, there were no fiber type differences in p62/SQSTM1, unc-51 like autophagy activating kinase (ULK1), ATG5, or ATG12 (P > 0.05). Compared with the fasted state, there was a reduction in LC3B-II abundance, indicative of lower autophagosome content, in whole muscle and in both type I and type II fibers following meal ingestion (P < 0.05). This reduction in autophagosome content occurred alongside similar increases in p-AktS473 and p-mTORS2448 in both type I and type II muscle fibers (P < 0.05). In human skeletal muscle, type I fibers have a greater autophagosome content than type II fibers in the overnight-fasted state despite comparable abundance of other key upstream autophagy proteins. Autophagy is rapidly inhibited in both fiber types following the ingestion of a mixed meal.NEW & NOTEWORTHY This study examined the fiber type-specific content of key autophagy proteins in human muscle. We showed that markers of autophagosome content are higher in type I fibers in the overnight-fasted state, whereas autophagy is rapidly inhibited in both type I and type II fibers after the ingestion of a mixed meal.

Ectonucleoside triphosphate diphosphohydrolase-1 (CD39) impacts TGF-ß1 responses: insights into cardiac fibrosis and function following myocardial infarction.

Extracellular purine nucleotides and nucleosides released from activated or injured cells influence multiple aspects of cardiac physiology and pathophysiology. Ectonucleoside triphosphate diphosphohydrolase-1 (ENTPD1; CD39) hydrolyzes released nucleotides and thereby regulates the magnitude and duration of purinergic signaling. However, the impact of CD39 activity on post-myocardial infarction (MI) remodeling is incompletely understood. We measured the levels and activity of ectonucleotidases in human left ventricular samples from control and ischemic cardiomyopathy (ICM) hearts and examined the impact of ablation of Cd39 expression on post-myocardial infarction remodeling in mice. We found that human CD39 levels and activity are significantly decreased in ICM hearts (n = 5) compared with control hearts (n = 5). In mice null for Cd39, cardiac function and remodeling are significantly compromised in Cd39-/- mice following myocardial infarction. Fibrotic markers including plasminogen activator inhibitor-1 (PAI-1) expression, fibrin deposition, α-smooth muscle actin (αSMA), and collagen expression are increased in Cd39-/- hearts. Importantly, we found that transforming growth factor ß1 (TGF-ß1) stimulates ATP release and induces Cd39 expression and activity on cardiac fibroblasts, constituting an autocrine regulatory pathway not previously appreciated. Absence of CD39 activity on cardiac fibroblasts exacerbates TGF-ß1 profibrotic responses. Treatment with exogenous ectonucleotidase rescues this profibrotic response in Cd39-/- fibroblasts. Together, these data demonstrate that CD39 has important interactions with TGF-ß1-stimulated autocrine purinergic signaling in cardiac fibroblasts and dictates outcomes of cardiac remodeling following myocardial infarction. Our results reveal that ENTPD1 (CD39) regulates TGF-ß1-mediated fibroblast activation and limits adverse cardiac remodeling following myocardial infarction.NEW & NOTEWORTHY We show that CD39 is a critical modulator of TGF-ß1-mediated fibroblast activation and cardiac remodeling following myocardial infarction via modulation of nucleotide signaling. TGF-ß1-induced CD39 expression generates a negative feedback loop that attenuates cardiac fibroblast activation. In the absence of CD39 activity, collagen deposition is increased, elastin expression is decreased, and diastolic dysfunction is worsened. Treatment with ecto-apyrase attenuates the TGF-ß1-induced profibrotic cardiac fibroblast phenotype, revealing a novel approach to combat post-myocardial infarction cardiac fibrosis.

Burnstock oration - purinergic signalling in kidney transplantation.

Kidney transplantation is the preferred treatment for individuals with kidney failure offering improved quality and quantity of life. Despite significant advancements in short term graft survival, longer term survival rates have not improved greatly mediated in large by chronic antibody mediated rejection. Strategies to reduce the donor kidney antigenic load may translate to improved transplant survival. CD39 on the vascular endothelium and on circulating cells, in particular regulatory T cells (Treg), is upregulated in response to hypoxic stimuli and plays a critical role in regulating the immune response removing proinflammatory ATP and generating anti-inflammatory adenosine. Herein, the role of CD39 in reducing ischaemia-reperfusion injury (IRI) and on Treg within the context of kidney transplantation is reviewed.

Too much sugar does not just make us fat; it can also make us sick.

The post-COVID-19 care era is likely to see a burgeoning of metabolic dysfunction and chronic kidney disease. Attention to self-care, including nutrition, will underpin the management of those affected. The damaging effects of sugar-sweetened beverages are well documented and profound and counter many accepted medical treatments. Government leadership is urgently required with explicit and strong messaging to avoid sugar-sweetened beverages.

Impact of COVID-19 on the worsening crisis of chronic kidney disease: the imperative to fund early detection is now.

The number of Australians affected by kidney disease will increase as the impacts of COVID-19 infection on kidney health are realised. Chronic kidney disease (CKD) imposes significant health and economic burdens from dialysis costs, loss of employment, premature death and increased admissions to hospital. Screening for kidney disease must be integrated into post-COVID-19 care; however, currently there is no reimbursement for kidney health checks in primary care. Early detection can reduce the progression of CKD by as much as 50% and thus the imperative to fund the Kidney Health Check is now.

Re-imaging healthcare delivery in the era of COVID-19.

The COVID-19 pandemic has exposed the deficiencies of the current healthcare system in terms of a disconnect between primary and tertiary care and increasing subspecialisation, the focus on acute episodic care rather than on prevention in a time where chronic disease prevails and an inefficient use of healthcare resources. Herein, we present the case for an alternative model of healthcare delivery - shared medical appointments - which are efficient, effective and empowering and can be transitioned to the virtual environment successfully. We highlight the barriers to implementation and how these can be overcome.

DNA methylation profiling identifies epigenetic differences between early versus late stages of diabetic chronic kidney disease.

BACKGROUND: We investigated a cross-sectional epigenome-wide association study of patients with early and late diabetes-associated chronic kidney disease (CKD) to identify possible epigenetic differences between the two groups as well as changes in methylation across all stages of diabetic CKD. We also evaluated the potential of using a panel of identified 5'-C-phosphate-G-3' (CpG) sites from this cohort to predict the progression of diabetic CKD. METHODS: This cross-sectional study recruited 119 adults. DNA was extracted from blood using the Qiagen QIAampDNA Mini Spin Kit. Genome-wide methylation analysis was performed using Illumina Infinium MethylationEPIC BeadChips (HM850K). Intensity data files were processed and analysed using the minfi and MissMethyl packages for R. We examined the degree of methylation of CpG sites in early versus late diabetic CKD patients for CpG sites with an unadjusted P-value <0.01 and an absolute change in methylation of 5% (n = 239 CpG sites). RESULTS: Hierarchical clustering of the 239 CpG sites largely separated the two groups. A heat map for all 239 CpG sites demonstrated distinct methylation patterns in the early versus late groups, with CpG sites showing evidence of progressive change. Based on our differentially methylated region (DMR) analysis of the 239 CpG sites, we highlighted two DMRs, namely the cysteine-rich secretory protein 2 (CRISP2) and piwi-like RNA-mediated gene silencing 1 (PIWIL1) genes. The best predictability for the two groups involved a receiver operating characteristics curve of eight CpG sites alone and achieved an area under the curve of 0.976. CONCLUSIONS: We have identified distinct DNA methylation patterns between early and late diabetic CKD patients as well as demonstrated novel findings of potential progressive methylation changes across all stages (1-5) of diabetic CKD at specific CpG sites. We have also identified associated genes CRISP2 and PIWIL1, which may have the potential to act as stage-specific diabetes-associated CKD markers, and showed that the use of a panel of eight identified CpG sites alone helps to increase the predictability for the two groups.

Overexpression of Human CD55 and CD59 or Treatment with Human CD55 Protects against Renal Ischemia-Reperfusion Injury in Mice.

Deficiency in the membrane-bound complement regulators CD55 and CD59 exacerbates renal ischemia-reperfusion injury (IRI) in mouse models, but the effect of increasing CD55 and CD59 activity has not been examined. In this study, we investigated the impact of overexpression of human (h) CD55 ± hCD59 or treatment with soluble rhCD55 in a mouse model of renal IRI. Unilaterally nephrectomised mice were subjected to 18 (mild IRI) or 22 min (moderate IRI) warm renal ischemia, and analyzed 24 h after reperfusion for renal function (serum creatinine and urea), complement deposition (C3b/c and C9), and infiltration of neutrophils and macrophages. Transgenic mice expressing hCD55 alone were protected against mild renal IRI, with reduced creatinine and urea levels compared with wild type littermates. However, the renal function of the hCD55 mice was not preserved in the moderate IRI model, despite a reduction in C3b/c and C9 deposition and innate cell infiltration. Mice expressing both hCD55 and hCD59, on the other hand, were protected in the moderate IRI model, with significant reductions in all parameters measured. Wild type mice treated with rhCD55 immediately after reperfusion were also protected in the moderate IRI model. Thus, manipulation of CD55 activity to increase inhibition of the C3 and C5 convertases is protective against renal IRI, and the additional expression of hCD59, which regulates the terminal complement pathway, provides further protection. Therefore, anti-complement therapy using complement regulatory proteins may provide a potential clinical option for preventing tissue and organ damage in renal IRI.

CD39 and CD73 activity are protective in a mouse model of antiphospholipid antibody-induced miscarriages.

OBJECTIVE: Antiphospholipid syndrome (APS) is a systemic autoimmune disorder of young adults associated with devastating pregnancy complications (recurrent miscarriages, preeclampsia and low birth weight) and vascular complications including thrombosis. The key components implicated in pathogenesis of APS are the complement cascade and tissue factor (TF) activity causing inflammation and coagulation. Purinergic signalling involving catabolism of ATP to adenosine by cell-surface enzymes CD39 and CD73 has anti-inflammatory and anti-thrombotic effects. We studied whether activities of CD39 and CD73 are important in preventing the development of miscarriages in APS. METHODS: We studied frequency of miscarriages and decidual pathology following passive transfer of human aPL-ab to pregnant wildtype mice, and mice deficient in CD39 and CD73, and also transgenic mice exhibiting 2-3X higher CD39 activity. RESULTS: aPL-ab infusion in pregnant CD39-or CD73-knockout mice triggers an increase in miscarriages, associated with increased TF expression and complement deposition as well as elevated oxidative stress and pro-inflammatory TNF-α and IL-10 expression within the placental decidua. In contrast, aPL-ab induced miscarriages are prevented in mice over-expressing CD39, with reduced decidual TF expression and C3d deposition, diminished lipid peroxidation (4-hydroxynonenal or 4-HNE positive lipid adducts), and reduced TNF-α expression. CONCLUSION: We demonstrate a protective role for CD39 in APS and provide rationale for both the development of endothelial cell-targeted soluble CD39 as a novel therapeutic for APS and analysis of perturbations in the purinergic pathway to explain human disease.

The adenosine, adrenergic and opioid pathways in the regulation of insulin secretion, beta cell proliferation and regeneration.

Insulin, a key hormone produced by pancreatic beta cells precisely regulates glucose metabolism in vertebrates. In type 1 diabetes, the beta cell mass is destroyed, a process triggered by a combination of environmental and genetic factors. This ultimately results in absolute insulin deficiency and dysregulated glucose metabolism resulting in a number of detrimental pathophysiological effects. The traditional focus of treating type 1 diabetes has been to control blood sugar levels through the administration of exogenous insulin. Newer approaches aim to replace the beta cell mass through pancreatic or islet transplantation. Type 2 diabetes results from a relative insulin deficiency for the prevailing insulin resistance. Treatments are generally aimed at reducing insulin resistance and/or augmenting insulin secretion and the use of insulin itself is often required. It is increasingly being recognized that the beta cell mass is dynamic and increases insulin secretion in response to beta cell mitogens and stress signals to maintain glycemia within a very narrow physiological range. This review critically discusses the role of adrenergic, adenosine and opioid pathways and their interrelationship in insulin secretion, beta cell proliferation and regeneration.

CD39-adenosinergic axis in renal pathophysiology and therapeutics.

Extracellular ATP interacts with purinergic type 2 (P2) receptors and elicits many crucial biological functions. Extracellular ATP is sequentially hydrolyzed to ADP and AMP by the actions of defined nucleotidases, such as CD39, and AMP is converted to adenosine, largely by CD73, an ecto-5'-nucleotidase. Extracellular adenosine interacts with P1 receptors and often opposes the effects of P2 receptor activation. The balance between extracellular ATP and adenosine in the blood and extracellular fluid is regulated chiefly by the activities of CD39 and CD73, which constitute the CD39-adenosinergic axis. In recent years, several studies have shown this axis to play critical roles in transport of water/sodium, tubuloglomerular feedback, renin secretion, ischemia reperfusion injury, renal fibrosis, hypertension, diabetic nephropathy, transplantation, inflammation, and macrophage transformation. Important developments include global and targeted gene knockout and/or transgenic mouse models of CD39 or CD73, biological or small molecule inhibitors, and soluble engineered ectonucleotidases to directly impact the CD39-adenosinergic axis. This review presents a comprehensive picture of the multiple roles of CD39-adenosinergic axis in renal physiology, pathophysiology, and therapeutics. Scientific advances and greater understanding of the role of this axis in the kidney, in both health and illness, will direct development of innovative therapies for renal diseases.

AMP and adenosine are both ligands for adenosine 2B receptor signaling.

Adenosine is considered the canonical ligand for the adenosine 2B receptor (A2BR). A2BR is upregulated following kidney ischemia augmenting post ischemic blood flow and limiting tubular injury. In this context the beneficial effect of A2BR signaling has been attributed to an increase in the pericellular concentration of adenosine. However, following renal ischemia both kidney adenosine monophosphate (AMP) and adenosine levels are substantially increased. Using computational modeling and calcium mobilization assays, we investigated whether AMP could also be a ligand for A2BR. The computational modeling suggested that AMP interacts with more favorable energy to A2BR compared with adenosine. Furthermore, AMPαS, a non-hydrolyzable form of AMP, increased calcium uptake by Chinese hamster ovary (CHO) cells expressing the human A2BR, indicating preferential signaling via the Gq pathway. Therefore, a putative AMP-A2BR interaction is supported by the computational modeling data and the biological results suggest this interaction involves preferential Gq activation. These data provide further insights into the role of purinergic signaling in the pathophysiology of renal IRI.

Bone health in chronic kidney disease-mineral and bone disorder: a clinical case seminar and update.

The metabolic abnormalities affecting bone in the setting of chronic kidney disease (CKD) are complex with overlapping and interacting aetiologies and have challenging diagnostic and management strategies. Disturbances in calcium, phosphate, fibroblast growth factor 23, parathyroid hormone concentrations and vitamin D deficiency are commonly encountered and contribute to the clinical syndromes of bone disorders in CKD, including hyperparathyroidism, osteomalacia, osteoporosis and adynamic bone disease. Mineral and bone abnormalities may also persist or arise de novo post-renal transplantation. The Kidney Disease Improving Global Outcomes organisation describes these mineral metabolism derangements and skeletal abnormalities as 'CKD Mineral and Bone Disorder'. Patients with this disorder have an increased risk of fracture, cardiovascular events and overall increased mortality. In light of the recently updated 2017 guidelines from the Kidney Disease Improving Global Outcomes, we present a clinical case-based discussion to highlight the complexities of investigating and managing the bone health of patients with CKD with a focus on these updates.

Phase 1/2 study of mogamulizumab, a defucosylated anti-CCR4 antibody, in previously treated patients with cutaneous T-cell lymphoma.

This phase 1/2 study evaluated the efficacy of mogamulizumab, a defucosylated, humanized, anti-CC chemokine receptor 4 monoclonal antibody, in 41 pretreated patients with cutaneous T-cell lymphoma. No dose-limiting toxicity was observed and the maximum tolerated dose was not reached in phase 1 after IV infusion of mogamulizumab (0.1, 0.3, and 1.0 mg/kg) once weekly for 4 weeks followed by a 2-week observation. In phase 2, patients were dosed with 1.0 mg/kg mogamulizumab according to the same schedule for the first course followed by infusion every 2 weeks during subsequent courses until disease progression. The most frequent treatment-emergent adverse events were nausea (31.0%), chills (23.8%), headache (21.4%), and infusion-related reaction (21.4%); the majority of events were grade 1/2. There were no significant hematologic effects. Among 38 evaluable patients, the overall response rate was 36.8%: 47.1% in Sézary syndrome (n = 17) and 28.6% in mycosis fungoides (n = 21). Eighteen of 19 (94.7%) patients with ≥B1 blood involvement had a response in blood, including 11 complete responses. Given the safety and efficacy of mogamulizumab, phase 3 investigation of mogamulizumab is warranted in cutaneous T-cell lymphoma patients. This trial was registered at www.clinicaltrials.gov as #NCT00888927.

Development of a novel strategy to target CD39 antithrombotic activity to the endothelial-platelet microenvironment in kidney ischemia-reperfusion injury.

Kidney ischemia-reperfusion injury (IRI) is common during transplantation. IRI is characterised by inflammation and thrombosis and associated with acute and chronic graft dysfunction. P-selectin and its ligand PSGL-1 are cell adhesion molecules that control leukocyte-endothelial and leukocyte-platelet interactions under inflammatory conditions. CD39 is the dominant vascular nucleotidase that facilitates adenosine generation via extracellular ATP/ADP-phosphohydrolysis. Adenosine signalling is protective in renal IRI, but CD39 catalytic activity is lost with exposure to oxidant stress. We designed a P-selectin targeted CD39 molecule (rsol.CD39-PSGL-1) consisting of recombinant soluble CD39 that incorporates 20 residues of PSGL-1 that bind P-selectin. We hypothesised that rsol.CD39-PSGL-1 would maintain endothelial integrity by focusing the ectonucleotidase platelet-inhibitory activity and reducing leukocyte adhesion at the injury site. The rsol.CD39-PSGL-1 displayed ADPase activity and inhibited platelet aggregation ex vivo, as well as bound with high specificity to soluble P-selectin and platelet surface P-selectin. Importantly, mice injected with rsol.CD39-PSGL-1 and subjected to renal IRI showed significantly less kidney damage both biochemically and histologically, compared to those injected with solCD39. Furthermore, the equivalent dose of rsol.CD39-PSGL-1 had no effect on tail template bleeding times. Hence, targeting recombinant CD39 to the injured vessel wall via PSGL-1 binding resulted in substantial preservation of renal function and morphology after IRI without toxicity. These studies indicate potential translational importance to clinical transplantation and nephrology.

Role of the CD39/CD73 Purinergic Pathway in Modulating Arterial Thrombosis in Mice.

OBJECTIVE: Circulating blood cells and endothelial cells express ectonucleoside triphosphate diphosphohydrolase-1 (CD39) and ecto-5'-nucleotidase (CD73). CD39 hydrolyzes extracellular ATP or ADP to AMP. CD73 hydrolyzes AMP to adenosine. The goal of this study was to examine the interplay between CD39 and CD73 cascade in arterial thrombosis. APPROACH AND RESULTS: To determine how CD73 activity influences in vivo thrombosis, the time to ferric chloride-induced arterial thrombosis was measured in CD73-null mice. In response to 5% FeCl3, but not to 10% FeCl3, there was a significant decrease in the time to thrombosis in CD73-null mice compared with wild-type mice. In mice overexpressing CD39, ablation of CD73 did not inhibit the prolongation in the time to thrombosis conveyed by CD39 overexpression. However, the CD73 inhibitor α-ß-methylene-ADP nullified the prolongation in the time to thrombosis in human CD39 transgenic (hC39-Tg)/CD73-null mice. To determine whether hematopoietic-derived cells or endothelial cell CD39 activity regulates in vivo arterial thrombus, bone marrow transplant studies were conducted. FeCl3-induced arterial thrombosis in chimeric mice revealed a significant prolongation in the time to thrombosis in hCD39-Tg reconstituted wild-type mice, but not on wild-type reconstituted hCD39-Tg mice. Monocyte depletion with clodronate-loaded liposomes normalized the time to thrombosis in hCD39-Tg mice compared with hCD39-Tg mice treated with control liposomes, demonstrating that increased CD39 expression on monocytes protects against thrombosis. CONCLUSIONS: These data demonstrate that ablation of CD73 minimally effects in vivo thrombosis, but increased CD39 expression on hematopoietic-derived cells, especially monocytes, attenuates in vivo arterial thrombosis.

Mineral adaptations following kidney transplantation.

Klotho is predominantly expressed in the kidney and reported to have antioxidant and antifibrotic properties. Soluble Klotho (sKl), the circulating protein cleaved from membrane-bound Klotho, is reduced significantly with kidney disease and inversely associated with mortality. sKl has not been thoroughly evaluated prospectively after kidney transplantation. Incident kidney transplant recipients (KTRs) were prospectively evaluated pretransplantation, 1, 12 and 52 weeks post-transplantation. Basic biochemistry, sKl and intact FGF23 were measured. Within-subject comparisons were evaluated using repeat-measure anova or Friedman's analysis. Effects of immunosuppression and biochemical parameters on sKl and FGF-23 over time were analysed using mixed-effects modelling. Median serum creatinine (sCr) at 1 week was 116 (92-142) µmol/l, and at 52 weeks, all 29 KTRs had a functioning graft with median sCr of 111 (97-131) µmol/l. Compared with baseline, sKl was increased at 52 weeks following an initial decline at 1 week (P < 0.005 and P < 0.01, respectively), while FGF23 was considerably reduced at 52 weeks (P < 0.001). In a mixed-effects model, an increased sKl was not associated with reduction in immunosuppression or evaluated biochemical parameters. Modest increase in sKl is observed one-year postkidney transplantation with excellent early graft function suggesting factors beyond renal capacity may influence circulating sKl. FGF23 normalization was observed. Longer term evaluation in transplantation, specifically addressing the effects of immunosuppression, is required to understand the pathophysiology of the sKl/FGF23 axis and potential for modification.

Evaluation of CD4+ CD25+/- CD39+ T-cell populations in peripheral blood of patients following kidney transplantation and during acute allograft rejection.

AIM: Regulatory T cells (Treg) are important in mediating immune tolerance and outcomes of allotransplantation. CD4+ CD25+ CD39+ co-expression identifies memory Treg; CD4+ CD25- CD39+ memory T effectors. We sought to determine CD4+ CD25+/- CD39+ expression from the peripheral blood of patients with end stage renal failure, following transplantation and during episodes of acute cellular rejection. METHODS: CD4+ T cells were isolated from peripheral blood leucocytes and analysed for CD25 and CD39 expression by flow cytometry. Treg suppressive function was measured by suppression of autologous effector T-cell proliferation by Treg in co-culture. RESULTS: CD4+ CD25+/- CD39+ T-cell subsets were tracked longitudinally in the peripheral blood of 17 patients following renal transplantation. Patients with acute T-cell-mediated rejection diagnosed on biopsy had reduced CD4+ CD25+ CD39+ mTreg (P < 0.05) and CD4+ CD25- CD39+ mTeff (P < 0.01) cells compared with non-rejecting patients. CD4+ CD25+ CD39+ mTreg (P < 0.05) and CD4+ CD25- CD39+ mTeff (P = 0.057) were reduced in long-term transplant patients (>1 year) compared with non-immunosuppressed controls. Interestingly, remaining CD4+ CD25+ CD39+ mTreg in the stable transplant patients displayed more potent suppressive capacity compared with non-immunosuppressed controls (83.2% ± 3.1% vs 45.7% ± 8.0%, nTeff:Treg ratio 8:1, P < 0.01). CONCLUSION: CD4+ CD25+ CD39+ mTreg and CD4+ CD25- CD39+ mTeff in peripheral blood can be tracked in renal transplant patients. Acute cellular rejection was accompanied by reduced mTreg and mTeff. Determining changes in these T-cell subsets may help to identify patients with, or at high risk of, renal allograft rejection.