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.

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.

Ectonucleoside triphosphate diphosphohydrolase-1 (CD39) impacts TGF-β1 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 β1 (TGF-β1) 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-β1 profibrotic responses. Treatment with exogenous ectonucleotidase rescues this profibrotic response in Cd39-/- fibroblasts. Together, these data demonstrate that CD39 has important interactions with TGF-β1-stimulated autocrine purinergic signaling in cardiac fibroblasts and dictates outcomes of cardiac remodeling following myocardial infarction. Our results reveal that ENTPD1 (CD39) regulates TGF-β1-mediated fibroblast activation and limits adverse cardiac remodeling following myocardial infarction.NEW & NOTEWORTHY We show that CD39 is a critical modulator of TGF-β1-mediated fibroblast activation and cardiac remodeling following myocardial infarction via modulation of nucleotide signaling. TGF-β1-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-β1-induced profibrotic cardiac fibroblast phenotype, revealing a novel approach to combat post-myocardial infarction cardiac fibrosis.

Re‐imaging health care delivery in the era of COVID‐19

The COVID‐19 pandemic has exposed the deficiencies of the current healthcare system of the 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, empowering and can be transitioned to the virtual environment successfully. We highlight the barriers to implementation and how these can be overcome.

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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-Akt^S473 and p-mTOR^S2448 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.

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.

Blood Plasma Metabolites in Diabetes-Associated Chronic Kidney Disease: A Focus on Lipid Profiles and Cardiovascular Risk

Background

We investigated a cross-sectional metabolomic analysis of plasma and urine of patients with early and late stage diabetes associated chronic kidney disease (CKD), inclusive of stages 1–5 CKD, to identify potential metabolomic profiles between the two groups.

Methods

This cross-sectional study recruited 119 adults. Metabolomic biomarkers were quantified in 119 non-fasted plasma and 57 urine samples using a high-throughput proton Nuclear Magnetic Resonance platform. Analyses were conducted using R with the ggforestplot package. Linear regression models were minimally adjusted for age, sex, and body mass index and p-values were adjusted for multiple comparisons using the Benjamini-Hockberg method with a false discovery rate of 0.05.

Results

Apolipoprotein A1 concentration (ApoA1) was reduced (adj. p = 0.04) and apolipoprotein B/apolipoprotein A1 ratio (ApoB/ApoA1) was increased (adj. p = 0.04) in late CKD compared with early CKD. Low-density lipoprotein triglyceride (LDL-TG) had an increased concentration (adj. p = 0.01), while concentrations of high-density lipoprotein cholesterol (HDL-C) were reduced (adj. p = 0.04) in late CKD compared to early stages of disease.

Conclusion

Our results highlight the presence of abnormal lipid metabolism namely significant reduction in the protective ApoA1 and significant increase in atherogenic ApoB/ApoA1 ratio. The study also demonstrates significantly elevated levels of triglyceride-rich lipoproteins such as LDL-TG. We illustrate the significant reduction in protective HDL-C in individuals with diabetic CKD. It explores a detailed plasma lipid profile that significantly differentiates between the late and early CKD groups as well as each CKD stage. The study of complex metabolite profiles may provide additional data required to enable more specific cardiovascular risk stratification.

Clinicians' perspectives on equity of access to dialysis and kidney transplantation for rural people in Australia: a semistructured interview study

OBJECTIVES

People with chronic kidney disease requiring dialysis or kidney transplantation in rural areas have worse outcomes, including an increased risk of hospitalisation and mortality and encounter many barriers to accessing kidney replacement therapy. We aim to describe clinicians' perspectives of equity of access to dialysis and kidney transplantation in rural areas.

DESIGN

Qualitative study with semistructured interviews.

SETTING AND PARTICIPANTS

Twenty eight nephrologists, nurses and social workers from 19 centres across seven states in Australia.

RESULTS

We identified five themes: the tyranny of distance (with subthemes of overwhelming burden of travel, minimising relocation distress, limited transportation options and concerns for patient safety on the roads); supporting navigation of health systems (reliance on local champions, variability of health literacy, providing flexible models of care and frustrated by gatekeepers); disrupted care (without continuity of care, scarcity of specialist services and fluctuating capacity for dialysis); pervasive financial distress (crippling out of pocket expenditure and widespread socioeconomic disadvantage) and understanding local variability (lacking availability of safe and sustainable resources for dialysis, sensitivity to local needs and dependence on social support).

CONCLUSIONS

Clinicians identified geographical barriers, dislocation from homes and financial hardship to be major challenges for patients in accessing kidney replacement therapy. Strategies such as telehealth, outreach services, increased service provision and patient navigators were suggested to improve access.

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.

Coprocytobiology: A Technical Review of Cytological Colorectal Cancer Screening in Fecal Samples

GRAPHICAL ABSTRACT

Gut Microbiome Composition Remains Stable in Individuals with Diabetes-Related Early to Late Stage Chronic Kidney Disease

(1) Background: Individuals with diabetes and chronic kidney disease display gut dysbiosis when compared to healthy controls. However, it is unknown whether there is a change in dysbiosis across the stages of diabetic chronic kidney disease. We investigated a cross-sectional study of patients with early and late diabetes associated chronic kidney disease to identify possible microbial differences between these two groups and across each of the stages of diabetic chronic kidney disease. (2) Methods: This cross-sectional study recruited 95 adults. DNA extracted from collected stool samples were used for 16S rRNA sequencing to identify the bacterial community in the gut. (3) Results: The phylum Firmicutes was the most abundant and its mean relative abundance was similar in the early and late chronic kidney disease group, 45.99 ± 0.58% and 49.39 ± 0.55%, respectively. The mean relative abundance for family Bacteroidaceae, was also similar in the early and late group, 29.15 ± 2.02% and 29.16 ± 1.70%, respectively. The lower abundance of Prevotellaceae remained similar across both the early 3.87 ± 1.66% and late 3.36 ± 0.98% diabetic chronic kidney disease groups. (4) Conclusions: The data arising from our cohort of individuals with diabetes associated chronic kidney disease show a predominance of phyla Firmicutes and Bacteroidetes. The families Ruminococcaceae and Bacteroidaceae represent the highest abundance, while the beneficial Prevotellaceae family were reduced in abundance. The most interesting observation is that the relative abundance of these gut microbes does not change across the early and late stages of diabetic chronic kidney disease, suggesting that this is an early event in the development of diabetes associated chronic kidney disease. We hypothesise that the dysbiotic microbiome acquired during the early stages of diabetic chronic kidney disease remains relatively stable and is only one of many risk factors that influence progressive kidney dysfunction.

Potential for Novel Biomarkers in Diabetes-Associated Chronic Kidney Disease: Epigenome, Metabolome, and Gut Microbiome

Diabetes-associated chronic kidney disease is a pandemic issue. Despite the global increase in the number of individuals with this chronic condition together with increasing morbidity and mortality, there are currently only limited therapeutic options to slow disease progression. One of the reasons for this is that the current-day "gold standard" biomarkers lack adequate sensitivity and specificity to detect early diabetic chronic kidney disease (CKD). This review focuses on the rapidly evolving areas of epigenetics, metabolomics, and the gut microbiome as potential sources of novel biomarkers in diabetes-associated CKD and discusses their relevance to clinical practice. However, it also highlights the problems associated with many studies within these three areas-namely, the lack of adequately powered longitudinal studies, and the lack of reproducibility of results which impede biomarker development and clinical validation in this complex and susceptible population.

The protective effects of human milk-derived peptides on the pancreatic islet biology

Several epidemiological studies support the protective role of breastfeeding in reducing the risk for type 1 diabetes. Human breast milk is the perfect nutrition for infants and contains many complex proteins, lipids and carbohydrates. In this study, we examined the physiological effects of human milk-derived opioid peptides, β-casomorphins (BCM), and compared them with bovine-milk-derived opioid peptides on pancreatic hormone regulation and β-cell regeneration. Exposure of wild-type zebrafish embryos to 50 µg/ml of human BCM-5 and -7 from 3 days post fertilisation until 6 days post fertilisation resulted in an increased insulin domain of expression while exposure to bovine BCM-5 and -7 significantly reduced the insulin domain of expression as analysed by whole-mount in situ hybridisation. These changes may be accounted for by reduced insulin expression or β-cell number and were mitigated by the µ-opioid receptor antagonist, naloxone. The effect of BCM on β-cell regeneration was assessed following ablation of β-cells in Tg (ins: CFP-NTR) zebrafish from 3 days post fertilisation to 4 days post fertilisation, followed by exposure of bovine and human BCM-5 and -7 (50 µg/ml) from 4 days post fertilisation until 7 days post fertilisation. The regenerative capacity of β-cells was not impeded following exposure to human BCM-5 and -7, whereas the capacity of β-cells to regenerate following bovine BCM-5 and -7 exposure was reduced. Our data suggest that human BCM-5 and -7 may promote β-cell development and enable the regeneration of β-cells, while the bovine-milk-derived peptides, BCM-5 and -7, play an opposite role. These data may provide some biological explanation for the protective effect of breastfeeding on the development of type 1 diabetes.

Identification of Potential Biomarkers of Chronic Kidney Disease in Individuals with Diabetes: Protocol for a Cross-sectional Observational Study

Background

The importance of identifying people with diabetes and progressive kidney dysfunction relates to the excess morbidity and mortality of this group. Rates of cardiovascular disease are much higher in people with both diabetes and kidney dysfunction than in those with only one of these conditions. By the time these people are identified in current clinical practice, proteinuria and renal dysfunction are already established, limiting the effectiveness of therapeutic interventions. The identification of an epigenetic or blood metabolite signature or gut microbiome profile may identify those with diabetes at risk of progressive chronic kidney disease, in turn providing targeted intervention to improve patient outcomes.

Objective

This study aims to identify potential biomarkers in people with diabetes and chronic kidney disease (CKD) associated with progressive renal injury and to distinguish between stages of chronic kidney disease. Three sources of biomarkers will be explored, including DNA methylation profiles in blood lymphocytes, the metabolomic profile of blood-derived plasma and urine, and the gut microbiome.

Methods

The cross-sectional study recruited 121 people with diabetes and varying stages (stages 1-5) of chronic kidney disease. Single-point data collection included blood, urine, and fecal samples in addition to clinical data such as anthropometric measurements and biochemical parameters. Additional information obtained from medical records included patient demographics, medical comorbidities, and medications.

Results

Data collection commenced in January 2018 and was completed in June 2018. At the time of submission, 121 patients had been recruited, and 119 samples remained after quality control. There were 83 participants in the early diabetes-associated CKD group with a mean estimated glomerular filtration rate (eGFR) of 61.2 mL/min/1.73 m2 (early CKD group consisting of stage 1, 2, and 3a CKD), and 36 participants in the late diabetic CKD group with a mean eGFR of 23.9 mL/min/1.73 m2 (late CKD group, consisting of stage 3b, 4, and 5), P<.001. We have successfully obtained DNA for methylation and microbiome analyses using the biospecimens collected via this protocol and are currently analyzing these results together with the metabolome of this cohort of individuals with diabetic CKD.

Conclusions

Recent advances have improved our understanding of the epigenome, metabolomics, and the influence of the gut microbiome on the incidence of diseases such as cancers, particularly those related to environmental exposures. However, there is a paucity of literature surrounding these influencers in renal disease. This study will provide insight into the fundamental understanding of the pathophysiology of CKD in individuals with diabetes, especially in novel areas such as epigenetics, metabolomics, and the kidney-gut axis.

International Registered Report Identifier (IRRID)

DERR1-10.2196/16277

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.

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.

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.

DNA methylation profiling of genomic DNA isolated from urine in diabetic chronic kidney disease: A pilot study

Aim

To characterise the genomic DNA (gDNA) yield from urine and quality of derived methylation data generated from the widely used Illuminia Infinium MethylationEPIC (HM850K) platform and compare this with buffy coat samples.

Background

DNA methylation is the most widely studied epigenetic mark and variations in DNA methylation profile have been implicated in diabetes which affects approximately 415 million people worldwide.

Methods

QIAamp Viral RNA Mini Kit and QIAamp DNA micro kit were used to extract DNA from frozen and fresh urine samples as well as increasing volumes of fresh urine. Matched buffy coats to the frozen urine were also obtained and DNA was extracted from the buffy coats using the QIAamp DNA Mini Kit. Genomic DNA of greater concentration than 20μg/ml were used for methylation analysis using the HM850K array.

Results

Irrespective of extraction technique or the use of fresh versus frozen urine samples, limited genomic DNA was obtained using a starting sample volume of 5ml (0–0.86μg/mL). In order to optimize the yield, we increased starting volumes to 50ml fresh urine, which yielded only 0–9.66μg/mL A different kit, QIAamp DNA Micro Kit, was trialled in six fresh urine samples and ten frozen urine samples with inadequate DNA yields from 0–17.7μg/mL and 0–1.6μg/mL respectively. Sufficient genomic DNA was obtained from only 4 of the initial 41 frozen urine samples (10%) for DNA methylation profiling. In comparison, all four buffy coat samples (100%) provided sufficient genomic DNA.

Conclusion

High quality data can be obtained provided a sufficient yield of genomic DNA is isolated. Despite optimizing various extraction methodologies, the modest amount of genomic DNA derived from urine, may limit the generalisability of this approach for the identification of DNA methylation biomarkers of chronic diabetic kidney disease.

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.

A1 beta-casein milk protein and other environmental pre-disposing factors for type 1 diabetes

Globally type 1 diabetes incidence is increasing. It is widely accepted that the pathophysiology of type 1 diabetes is influenced by environmental factors in people with specific human leukocyte antigen haplotypes. We propose that a complex interplay between dietary triggers, permissive gut factors and potentially other influencing factors underpins disease progression. We present evidence that A1 β-casein cows’ milk protein is a primary causal trigger of type 1 diabetes in individuals with genetic risk factors. Permissive gut factors (for example, aberrant mucosal immunity), intervene by impacting the gut’s environment and the mucosal barrier. Various influencing factors (for example, breastfeeding duration, exposure to other dietary triggers and vitamin D) modify the impact of triggers and permissive gut factors on disease. The power of the dominant trigger and permissive gut factors on disease is influenced by timing, magnitude and/or duration of exposure. Within this framework, removal of a dominant dietary trigger may profoundly affect type 1 diabetes incidence. We present epidemiological, animal-based, in vitro and theoretical evidence for A1 β-casein and its β-casomorphin-7 derivative as dominant causal triggers of type 1 diabetes. The effects of ordinary milk containing A1 and A2 β-casein and milk containing only the A2 β-casein warrant comparison in prospective trials.

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.

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.

CD39 overexpression does not attenuate renal fibrosis in the unilateral ureteric obstructive model of chronic kidney disease

Chronic kidney disease has multiple etiologies, but its single, hallmark lesion is renal fibrosis. CD39 is a key purinergic enzyme in the hydrolysis of ATP and increased CD39 activity on regulatory T cells (Treg) is protective in adriamycin-induced renal fibrosis. We examined the effect of overexpression of human CD39 on the development of renal fibrosis in the unilateral ureteric obstructive (UUO) model, a model widely used to study the molecular and cellular factors involved in renal fibrosis. Mice overexpressing human CD39 (CD39Tg) and their wild-type (WT) littermates were subjected to UUO; renal histology and messenger RNA (mRNA) levels of adenosine receptors and markers of renal fibrosis were examined up to 14 days after UUO. There were no differences between CD39Tg mice and WT mice in the development of renal fibrosis at days 3, 7, and 14 of UUO. Relative mRNA expression of the adenosine A_2A receptor and endothelin-1 were higher in CD39Tg than WT mice at day 7 post UUO, but there were no differences in markers of fibrosis. We conclude that human CD39 overexpression does not attenuate the development of renal fibrosis in the UUO model. The lack of protection by CD39 overexpression in the UUO model is multifactorial due to the different effects of adenosinergic receptors on the development of renal fibrosis.

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-β-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.

Abstract 341: The Role of Nucleotidase in Arterial Thrombosis

Objective: To determine how leukocyte nucleotidase affects arterial thrombosis.

Approach and Results: Ectonucleoside triphosphate diphosphohydrolase-1 (CD39) is expressed on circulating cells, endothelium and smooth muscle cells where it hydrolyzes extracellular ATP or ADP to AMP. We have demonstrated that transgenic mice with a global overexpression of human CD39 (hCD39-Tg) are protected against ferric chloride-induced carotid artery thrombosis. Furthermore, transplant of hCD39-Tg bone marrow into WT recipient mice increases the time to thrombosis when compared to recipient mice (wild-type or hCD39-Tg) receiving wild-type bone marrow. Based upon these data and previously published work, we hypothesized that CD39 expression on leukocytes is responsible for the prolongation of the time to thrombosis measured in hCD39-Tg mice. To test this hypothesis, we first performed ex vivo mixing experiments. Addition of hCD39-Tg monocytes to WT blood inhibits the expression of activated glycoprotein IIb/IIIa on platelets in response to ADP as measured by FACS analysis (Baseline: 1224 ± 94.9 MFI vs hCD39-Tg monocytes: 663.5 ± 61.5 activated glycoprotein IIb/IIIa MFI: n=4; p< 0.001). Subsequently, in vivo we demonstrated that monocytes with increased CD39 contribute to extending the time to thrombosis. Clodronate liposome depletion of monocytes (WT: 69% decrease; hCD39-Tg: 63% decrease) resulted in a normalization of the time to thrombosis in hCD39-Tg mice (8.0 ± 1.07 minutes, n = 10) when compared to control loaded liposomes (120.0 ± 0.0, n = 14). No changes in the time to thrombosis were detected in wild-type mice treated with clodronate (8.6 ± 1.35 minutes, n = 8) or control liposomes (7.8 ± 0.80 minutes, n=8).

Conclusion: Increased expression of CD39 on monocytes can inhibit platelet activation and extend the time to thrombosis following ferric chloride-induced carotid artery injury.

Adenosine receptor expression in the development of renal fibrosis following ischemic injury

Long-term renal allograft survival has not improved despite improvements in short term outcomes. Graft loss is characterized histologically by the development of interstitial fibrosis and tubular atrophy (IFTA). Mechanisms underlying the development of IFTA are multifactorial and include ischemia-reperfusion injury (IRI). Therapeutic options to reduce IFTA include management of immunologic causes, such as rejection, but despite these efforts IFTA can still occur and leads to the inexorable destruction of the transplanted kidney. The adenosine A2B receptor (A2BR) has recently been implicated in the development of renal fibrosis. We performed an observational study to examine the mRNA expression of the adenosine receptors after renal ischemia up to the development of renal fibrosis in a mouse model of unilateral IRI. A2BR was the only adenosine receptor that showed elevated expression following ischemia until the development of renal fibrosis 4 weeks after injury. At 2 weeks after ischemia, increased expression of the fibrotic markers transforming growth factor β and Collagen-1α was observed. Expression of hypoxia inducible factor 1α and endothelin-1, which lie downstream of A2BR activation and have been recognized to promote renal fibrosis, were also significantly up-regulated at 2 weeks after ischemia. Expression of fibrotic markers returned to baseline by 4 weeks after ischemia, indicating resolution of injury with the concurrent development of renal fibrosis and reduced renal function. Our data suggest that A2BR may be a therapeutic target in reducing the development of renal fibrosis after ischemia.

Abstract 75: Ischemic Heart Failure is Exacerbated in CD39-null Mice

Background: CD39 (ectonucleoside triphosphate diphosphohydrolase) is a nucleotidase expressed on endothelial cells, vascular smooth muscles cells, and leukocytes. CD39 plays a key role in vascular homeostasis, hydrolyzing extracellular ATP and ADP. CD39 has been shown to be important in models of ischemic preconditioning and cardiac ischemia reperfusion. However, the effect of CD39 activity on functional recovery of heart after myocardial infarction (MI) has not been evaluated.

Hypothesis: Genetic ablation of CD39 expression exacerbates post-myocardial infarction cardiac function and fibrosis.

Methods: Wild-type (WT) and CD39-null mice were subjected to coronary artery ligation. Cardiac function and protein evaluation of fibrotic markers was performed at day 28 post-MI.

Results: Evaluation at Day 28 post-MI revealed that while mice of both genotypes had similarly reduced ejection fraction and equally compromised contractile function (dP/dtmax), there was a more pronounced negative effect on lusitropy (dP/dtmin) and increased left ventricular end-diastolic pressure in CD39-null mice. Therefore, cd39 gene ablation associates with the development of worsening cardiac performance. Histological analysis revealed increased collagen deposition and abundance of alpha-smooth muscle actin (αSMA) positive interstitial cells in the CD39-null hearts compared to WT hearts. To quantify these findings immunoblot analysis for collagen and αSMA was performed. We found that collagen and αSMA were increased at Day 28 post-MI, in CD39-null hearts compared to WT hearts.

Conclusion: CD39 ablation has detrimental effects on post-MI recovery, resulting in diminished cardiac performance and increased fibrosis.

A case of triple pathology: seronegative anti-glomerular basement membrane antibody-mediated glomerulonephritis and membranous nephropathy in a patient with underlying diabetic kidney disease

In diabetic patients with acute kidney injury (AKI), kidney biopsy often reveals non-diabetic kidney pathology. This case describes a patient with known Type 1 diabetes who presented with AKI, nephrotic syndrome and haematuria. Combination pathology of seronegative anti-glomerular basement membrane antibody-mediated glomerulonephritis (anti-GBM GN), membranous nephropathy (MN) and diabetic nephropathy (DN) was demonstrated. Strong linear GBM IgG-staining on biopsy with crescentic GN and clinical AKI led to a diagnosis of anti-GBM GN, although serum antibodies were not detectable. Features of DN, Kimmelstiel-Wilson nodules and albumin staining were also present, along with features of MN, such as subepithelial deposits on electron microscopy. Despite treatment with immunosuppression and plasmapheresis, there was no recovery of kidney function. Coexisting anti-GBM GN and MN is well recognized, but the concurrent diagnosis with DN has not been described.

Spectrum of renal disease in diabetes

The spectrum of renal disease in patients with diabetes encompasses both diabetic kidney disease (including albuminuric and non-albuminuric phenotypes) and non-diabetic kidney disease. Diabetic kidney disease can manifest as varying degrees of renal insufficiency and albuminuria, with heterogeneity in histology reported on renal biopsy. For patients with diabetes and proteinuria, the finding of non-diabetic kidney disease alone or superimposed on the changes of diabetic nephropathy is increasingly reported. It is important to identify non-diabetic kidney disease as some forms are treatable, sometimes leading to remission. Clinical indications for a heightened suspicion of non-diabetic kidney disease and hence consideration for renal biopsy in patients with diabetes and nephropathy include absence of diabetic retinopathy, short duration of diabetes, atypical chronology, presence of haematuria or other systemic disease, and the nephrotic syndrome.

Impaired natriuretic response to high-NaCl diet plus aldosterone infusion in mice overexpressing human CD39, an ectonucleotidase (NTPDase1)

Extracellular nucleotides acting through P2 receptors facilitate natriuresis. To define how purinergic mechanisms are involved in sodium homeostasis, we used transgenic (TG) mice that globally overexpress human CD39 (hCD39, NTPDase1), an ectonucleotidase that hydrolyzes extracellular ATP/ADP to AMP, resulting in an altered extracellular purine profile. On a high-sodium diet (HSD, 3.5% Na(+)), urine volume and serum sodium were significantly higher in TG mice but sodium excretion was unaltered. Furthermore, TG mice showed an attenuated fall in urine aldosterone with HSD. Western blot analysis revealed significantly lower densities (∼40%) of the β-subunit of the epithelial sodium channel (ENaC) in medulla, and the major band (85-kDa) of γ-ENaC in TG mice cortex. To evaluate aldosterone-independent differences, in a second experiment, aldosterone was clamped by osmotic minipump at 20 μg/day, and mice were fed either an HSD or a low-sodium diet (LSD, 0.03% Na(+)). Here, no differences in urine volume or osmolality, or serum aldosterone were found, but TG mice showed a modest, yet significant impairment in late natriuresis (days 3 and 4). Several major sodium transporters or channel subunits were differentially expressed between the genotypes. HSD caused a downregulation of Na-Cl cotransporter (NCC) in both genotypes; and had higher cortical levels of NCC, Na-K-ATPase (α-1 subunit), and α- and γ-ENaC. The Na-K-2Cl cotransporter (NKCC2) was downregulated by HSD in wild-type mice, but it increased in TG mice. In summary, our data support the concept that extracellular nucleotides facilitate natriuresis; they also reveal an aldosterone-independent downregulation of major renal sodium transporters and channel subunits by purinergic signaling.

Recurrent Mycobacterium haemophilum in a renal transplant recipient

Mycobacterium haemophilum is a rare isolate of non-tuberculous Mycobacterium which has been reported to affect immunocompromised patients. We report a case of a 32-year-old renal transplant patient with M.  haemophilum infection initially involving his left sinus which was treated with appropriate antimicrobial therapy for thirteen months. Two weeks after cessation of antibiotics the infection rapidly recurred in his skin and soft tissues of his hands and feet. This case highlights the difficult diagnostic and therapeutic implications of atypical infections in transplant patients. To our knowledge this is the first reported case of relapsed M.  haemophilum infection in a renal transplant recipient.

Abstract 19: CD39 Expression on Circulating Blood Components Prolongs the Time to Ferric Chloride--Induced Carotid Artery Thrombosis in Mice

Objective: To determine the effect of increased CD39 expression on circulating blood components on in vivo arterial thrombosis in mice.

Approach and Results: We have previously demonstrated that increased global expression of hCD39 conveys an anti-thrombotic phenotype in mice suggesting a pivotal role for CD39 in modulating the balance between a pro-thrombotic and anti-thrombotic milieu. We hypothesized the expression of CD39 on circulating blood components can regulate occlusive thrombus formation. Bone marrow transplantations were performed (WT to WT; WT to hCD39-Tg; hCD39-Tg to hCD39-Tg; hCD39-Tg to WT) to determine the contribution of CD39 expressed on circulating blood cells and platelets on occlusive arterial thrombus formation in mice. Complete blood counts and fluorescence-activated cell sorting (FACS) analyses were performed on whole blood obtained from mice 60 days after transplantation of bone marrow. No significant differences in the circulating levels of white blood cells, red blood cells, and platelets were observed between the groups. FACS analysis confirmed that the circulating blood components were reconstituted from the transplanted bone marrow. Carotid artery thrombosis was induced by ferric chloride (FeCl 3 ) application and the time to thrombotic occlusion (blood flow of 0 ml/min) was measured. The operator was blinded to the animal genotype and treatment during all experiments. Transplantation of CD39-Tg bone marrow into WT mice resulted in a marked resistance to thrombosis (CD39-Tg to WT: 315.7.00 ± 54.6 min; WT to WT: 7.58 ± 0.89 min; P <0.001). CD39-Tg mice that received WT bone marrow demonstrated a significantly lower time to vessel occlusion than CD39-Tg mice that received CD39-Tg bone marrow (WT to CD39-Tg: 17.15 ± 6 min; CD39-Tg to CD39-Tg 414.3 ± 61.95 min; P <0.001).

Conclusion: Increased expression of CD39 on circulating bone-marrow-derived blood components markedly prolongs the time to carotid artery occlusion following ferric-chloride-induced injury in mice.

The Role of Ectonucleotidases CD39 and CD73 and Adenosine Signaling in Solid Organ Transplantation

Extracellular adenosine is a potent immunomodulatory molecule that accumulates in states of inflammation. Nucleotides such as adenosine triphosphate and adenosine diphosphate are release from injured and necrotic cells and hydrolyzed to adenosine monophosphate and adenosine by the concerted action of the ectonucleotidases CD39 and CD73. Accumulating evidence suggest that purinergic signaling is involved in the inflammatory response that accompanies acute rejection and chronic allograft dysfunction. Modification of the purinergic pathway has been shown to alter graft survival in a number of solid organ transplant models and the response to ischemia–reperfusion injury (IRI). Furthermore, the purinergic pathway is intrinsically involved in B and T cell biology and function. Although T cells have traditionally been considered the orchestrators of acute allograft rejection, a role for B cells in chronic allograft loss is being increasingly appreciated. This review focuses on the role of the ectonucleotidases CD39 and CD73 and adenosine signaling in solid organ transplantation including the effects on IRI and T and B cell biology.

Overexpression of CD39 protects in a mouse model of preeclampsia

CD39 (NTPDase1), a critical immune and vascular ecto-nucleotidase, hydrolyses pro-inflammatory and pro-thrombotic nucleotides (adenosine-5'-triphosphate (ATP) and adenosine diphosphate) to adenosine. In humans, CD39 is the dominant ecto-nucleotidase in placental trophoblastic tissues and modulates ATP-dependent trophoblastic functions. CD39 is an integral component of regulatory T cells (Treg), which are central to immunological tolerance and maintenance of normal pregnancy. We examined the impact of CD39 overexpression in a mouse model of preeclampsia. Matings were performed between virginal BALB/c female (wild-type (WT) or CD39 transgenic (CD39TG)) and C57BL/6 male mice. On days 10 and 12 of pregnancy BALB/c Th1-polarized cells were injected. Systolic blood pressure (SBP) was measured throughout pregnancy. Mice were sacrificed at day 15 of pregnancy. Following transfer of Th1-polarized cells, SBP of pregnant WT mice increased (118 ± 3 mmHg to 142 ± 5 mmHg). Although ultrastructural changes were evident in the kidney this was not accompanied by significant proteinuria. SBP remained unchanged (115 ± 2 mmHg to 114 ± 3 mmHg) in pregnant CD39TG mice without evidence of renal lesions. We conclude that gestational hypertension can be induced in mice following transfer of maternally derived Th1-polarized cells and that overexpression of CD39 is protective in this model.

Differential migration of passenger leukocytes and rapid deletion of naive alloreactive CD8 T cells after mouse liver transplantation

Donor passenger leukocytes (PLs) from transplanted livers migrate to recipient lymphoid tissues, where they are thought to induce the deletion of donor-specific T cells and tolerance. Difficulties in tracking alloreactive T cells and PLs in rats and in performing this complex surgery in mice have limited progress in identifying the contribution of PL subsets and sites and the kinetics of T cell deletion. Here we developed a mouse liver transplant model in which PLs, recipient cells, and a reporter population of transgenic CD8 T cells specific for the graft could be easily distinguished and quantified in allografts and recipient organs by flow cytometry. All PL subsets circulated rapidly via the blood as soon as 1.5 hours after transplantation. By 24 hours, PLs were distributed differently in the lymph nodes and spleen, whereas donor natural killer and natural killer T cells remained in the liver and blood. Reporter T cells were activated in both liver and lymphoid tissues, but their numbers dramatically decreased within the first 48 hours. These results provide the first unequivocal demonstration of the differential recirculation of liver PL subsets after transplantation, and show that alloreactive CD8 T cells are deleted more rapidly than initially reported. This model will be useful for dissecting early events leading to the spontaneous acceptance of liver transplants.

Sustained function of genetically modified porcine lungs in an ex vivo model of pulmonary xenotransplantation

BACKGROUND

Xenotransplantation could provide a solution to the donor shortage that is currently the major barrier to solid-organ transplantation. The ability to breed pigs with multiple genetic modifications provides a unique opportunity to explore the immunologic challenges of pulmonary xenotransplantation.

METHODS

Explanted lungs from wild-type and 3 groups of genetically modified pigs were studied: (i) α1,3-galactosyltransferase gene knockout (GTKO); (ii) GTKO pigs expressing the human complementary regulatory proteins CD55 and CD59 (GTKO/CD55-59); and (iii) GTKO pigs expressing both CD55-59 and CD39 (GTKO/CD55-59/CD39). The physiologic, immunologic and histologic properties of porcine lungs were evaluated on an ex vivo rig after perfusion with human blood.

RESULTS

Lungs from genetically modified pigs demonstrated stable pulmonary vascular resistance and better oxygenation of the perfusate, and survived longer than wild-type lungs. Physiologic function was inversely correlated with the degree of platelet sequestration into the xenograft. Despite superior physiologic profiles, lungs from genetically modified pigs still showed evidence of intravascular thrombosis and coagulopathy after perfusion with human blood.

CONCLUSIONS

The ability to breed pigs with multiple genetic modifications, and to evaluate lung physiology and histology in real-time on an ex vivo rig, represent significant advances toward better understanding the challenges inherent to pulmonary xenotransplantation.