P2X7 receptor knockout does not alter renal function or prevent angiotensin II-induced kidney injury in F344 rats.

P2X7 receptors mediate immune and endothelial cell responses to extracellular ATP. Acute pharmacological blockade increases renal blood flow and filtration rate, suggesting that receptor activation promotes tonic vasoconstriction. P2X7 expression is increased in kidney disease and blockade/knockout is renoprotective. We generated a P2X7 knockout rat on F344 background, hypothesising enhanced renal blood flow and protection from angiotensin-II-induced renal injury. CRISPR/Cas9 introduced an early stop codon into exon 2 of P2rx7, abolishing P2X7 protein in kidney and reducing P2rx7 mRNA abundance by ~ 60% in bone-marrow derived macrophages. The M1 polarisation response to lipopolysaccharide was unaffected but P2X7 receptor knockout suppressed ATP-induced IL-1ß release. In male knockout rats, acetylcholine-induced dilation of the renal artery ex vivo was diminished but not the response to nitroprusside. Renal function in male and female knockout rats was not different from wild-type. Finally, in male rats infused with angiotensin-II for 6 weeks, P2X7 knockout did not reduce albuminuria, tubular injury, renal macrophage accrual, and renal perivascular fibrosis. Contrary to our hypothesis, global P2X7 knockout had no impact on in vivo renal hemodynamics. Our study does not indicate a major role for P2X7 receptor activation in renal vascular injury.

Endothelin-1 Mediates the Systemic and Renal Hemodynamic Effects of GPR81 Activation.

GPR81 (G-protein-coupled receptor 81) is highly expressed in adipocytes, and activation by the endogenous ligand lactate inhibits lipolysis. GPR81 is also expressed in the heart, liver, and kidney, but roles in nonadipose tissues are poorly defined. GPR81 agonists, developed to improve blood lipid profile, might also provide insights into GPR81 physiology. Here, we assessed the blood pressure and renal hemodynamic responses to the GPR81 agonist, AZ'5538. In male wild-type mice, intravenous AZ'5538 infusion caused a rapid and sustained increase in systolic and diastolic blood pressure. Renal artery blood flow, intrarenal tissue perfusion, and glomerular filtration rate were all significantly reduced. AZ'5538 had no effect on blood pressure or renal hemodynamics in Gpr81-/- mice. Gpr81 mRNA was expressed in renal artery vascular smooth muscle, in the afferent arteriole, in glomerular and medullary perivascular cells, and in pericyte-like cells isolated from kidney. Intravenous AZ'5538 increased plasma ET-1 (endothelin 1), and pretreatment with BQ123 (endothelin-A receptor antagonist) prevented the pressor effects of GPR81 activation, whereas BQ788 (endothelin-B receptor antagonist) did not. Renal ischemia-reperfusion injury, which increases renal extracellular lactate, increased the renal expression of genes encoding ET-1, KIM-1 (Kidney Injury Molecule 1), collagen type 1-α1, TNF-α (tumor necrosis factor-α), and F4/80 in wild-type mice but not in Gpr81-/- mice. In summary, activation of GPR81 in vascular smooth muscle and perivascular cells regulates renal hemodynamics, mediated by release of the potent vasoconstrictor ET-1. This suggests that lactate may be a paracrine regulator of renal blood flow, particularly relevant when extracellular lactate is high as occurs during ischemic renal disease.

Transcription controls growth, cell kinetics and cholesterol supply to sustain ACTH responses.

Chronic ACTH exposure is associated with adrenal hypertrophy and steroidogenesis. The underlying molecular processes in mice have been analysed by microarray, histological and immunohistochemical techniques. Synacthen infused for 2 weeks markedly increased adrenal mass and plasma corticosterone levels. Microarray analysis found greater than 2-fold changes in expression of 928 genes (P < 0.001; 397 up, 531 down). These clustered in pathways involved in signalling, sterol/lipid metabolism, cell proliferation/hypertrophy and apoptosis. Signalling genes included some implicated in adrenal adenomas but also upregulated genes associated with cyclic AMP and downregulated genes associated with aldosterone synthesis. Sterol metabolism genes were those promoting cholesterol supply (Scarb1, Sqle, Apoa1) and disposal (Cyp27a1, Cyp7b1). Oil red O staining showed lipid depletion consistent with reduced expression of genes involved in lipid synthesis. Genes involved in steroidogenesis (Star, Cyp11a1, Cyp11b1) were modestly affected (P < 0.05; <1.3-fold). Increased Ki67, Ccna2, Ccnb2 and Tk1 expression complemented immunohistochemical evidence of a 3-fold change in cell proliferation. Growth arrest genes, Cdkn1a and Cdkn1c, which are known to be active in hypertrophied cells, were increased >4-fold and cross-sectional area of fasciculata cells was 2-fold greater. In contrast, genes associated with apoptosis (eg Casp12, Clu,) were downregulated and apoptotic cells (Tunel staining) were fewer (P < 0.001) and more widely distributed throughout the cortex. In summary, long-term steroidogenesis with ACTH excess is sustained by genes controlling cholesterol supply and adrenal mass. ACTH effects on adrenal morphology and genes controlling cell hypertrophy, proliferation and apoptosis suggest the involvement of different cell types and separate molecular pathways.

Hyperglycemia-induced Renal P2X7 Receptor Activation Enhances Diabetes-related Injury.

Diabetes is a leading cause of renal disease. Glomerular mesangial expansion and fibrosis are hallmarks of diabetic nephropathy and this is thought to be promoted by infiltration of circulating macrophages. Monocyte chemoattractant protein-1 (MCP-1) has been shown to attract macrophages in kidney diseases. P2X7 receptors (P2X7R) are highly expressed on macrophages and are essential components of pro-inflammatory signaling in multiple tissues. Here we show that in diabetic patients, renal P2X7R expression is associated with severe mesangial expansion, impaired glomerular filtration (≤40ml/min/1.73sq.m.), and increased interstitial fibrosis. P2X7R activation enhanced the release of MCP-1 in human mesangial cells cultured under high glucose conditions. In mice, P2X7R-deficiency prevented glomerular macrophage attraction and collagen IV deposition; however, the more severe interstitial inflammation and fibrosis often seen in human diabetic kidney diseases was not modelled. Finally, we demonstrate that a P2X7R inhibitor (AZ11657312) can reduce renal macrophage accrual following the establishment of hyperglycemia in a model of diabetic nephropathy. Collectively these data suggest that P2X7R activation may contribute to the high prevalence of kidney disease found in diabetics.

Purinergic signaling in kidney disease.

Nucleotides are key subunits for nucleic acids and provide energy for intracellular metabolism. They can also be released from cells to act physiologically as extracellular messengers or pathologically as danger signals. Extracellular nucleotides stimulate membrane receptors in the P2 and P1 family. P2X are ATP-activated cation channels; P2Y and P1 are G-protein coupled receptors activated by ATP, ADP, UTP, and UDP in the case of P2 or adenosine for P1. Renal P2 receptors influence both vascular contractility and tubular function. Renal cells also express ectonucleotidases that rapidly hydrolyze extracellular nucleotides. These enzymes integrate this multireceptor purinergic-signaling complex by determining the nucleotide milieu to titrate receptor activation. Purinergic signaling also regulates immune cell function by modulating the synthesis and release of various cytokines such as IL1-ß and IL-18 as part of inflammasome activation. Abnormal or excessive stimulation of this intricate paracrine system can be pro- or anti-inflammatory, and is also linked to necrosis and apoptosis. Kidney tissue injury causes a localized increase in ATP concentration, and sustained activation of P2 receptors can lead to renal glomerular, tubular, and vascular cell damage. Purinergic receptors also regulate the activity and proliferation of fibroblasts, promoting both inflammation and fibrosis in chronic disease. In this short review we summarize some of the recent findings related to purinergic signaling in the kidney. We focus predominantly on the P2X7 receptor, discussing why antagonists have so far disappointed in clinical trials and how advances in our understanding of purinergic signaling might help to reposition these compounds as potential treatments for renal disease.

Intussusception after monovalent human rotavirus vaccine in Australia: severity and comparison of using healthcare database records versus case confirmation to assess risk.

BACKGROUND: Surveillance for intussusception (IS) has been recommended in countries using rotavirus vaccine, but can be resource intensive. There is little data about the relative severity of rotavirus vaccine-associated IS compared with other IS cases. We collected detailed clinical data on all cases to evaluate the validity of ICD coding for IS in routinely collected data and case severity. METHODS: Hospitalizations and emergency department presentations coded as IS in infants aged <12 months from July 1, 2007, to June 30, 2010, were classified using Brighton criteria by case note review. We used self-controlled case series analysis to estimate IS risk after vaccination for all and only Brighton level 1 cases. RESULTS: Of 179 unique episodes coded as IS, 110 (61%) met Brighton level 1 criteria; self-controlled case series analysis found a relative incidence of IS in days 1-7 after the first dose of RV1 of 11.1 (95% confidence interval: 2.6-48.0). When all coded episodes of IS were included, relative incidence was 4.0 (95% confidence interval: 1.3-12.7). The proportion of Brighton 1 cases requiring surgery was 39% for those within 21 days of vaccine receipt and 34% for others (P = 0.67). CONCLUSIONS: Using ICD-coded cases without individual confirmation yielded a lower point estimate of risk for IS post rotavirus vaccination; however, the risk remained statistically compatible with that for chart confirmed cases only. Analysis using healthcare databases to evaluate risk of IS if conducted without case confirmation may be insufficient to confirm a low-level risk. IS episodes after vaccination were not more severe.

NSW annual immunisation coverage report, 2011.

UNLABELLED: This annual report, the third in the series, documents trends in immunisation coverage in NSW for children, adolescents and the elderly, to the end of 2011. METHODS: Data from the Australian Childhood Immunisation Register, the NSW School Immunisation Program and the NSW Population Health Survey were used to calculate various measures of population coverage. RESULTS: During 2011, greater than 90% coverage was maintained for children at 12 and 24 months of age. For children at 5 years of age the improvement seen in 2010 was sustained, with coverage at or near 90%. For adolescents, there was improved coverage for all doses of human papillomavirus vaccine, both doses of hepatitis B vaccine, varicella vaccine and the dose of diphtheria, tetanus and acellular pertussis given to school attendees in Years 7 and 10. Pneumococcal vaccination coverage in the elderly has been steadily rising, although it has remained lower than the influenza coverage estimates. CONCLUSION: This report provides trends in immunisation coverage in NSW across the age spectrum. The inclusion of coverage estimates for the pneumococcal conjugate, varicella and meningococcal C vaccines in the official coverage assessments for 'fully immunised' in 2013 is a welcome initiative.

NSW annual immunisation coverage report, 2010.

UNLABELLED: This annual report, the second in the series, documents trends in immunisation coverage in NSW for children, adolescents and the elderly, to the end of 2010. METHODS: Data from the Australian Childhood Immunisation Register, the NSW School Immunisation Program and the NSW Population Health Survey were used to calculate various measures of population coverage, coverage for Aboriginal children and vaccination timeliness for all children. RESULTS: Over 90% coverage has been reached for children at 12 and 24 months of age. For children at 5 years of age there was an improvement during 2010 in timeliness for vaccines due at 4 years and coverage almost reached 90%. Delayed receipt of vaccines is still an issue for Aboriginal children. For adolescents, there is good coverage for the first and second doses of human papillomavirus vaccine and the dose of diphtheria, tetanus and acellular pertussis. The pneumococcal vaccination rate in the elderly has been steadily rising, although it has remained lower than the influenza coverage estimates. CONCLUSION: Completion of the recommended immunisation schedule at the earliest appropriate age should be the next public health goal at both the state and local health district level. Official coverage assessments for 'fully immunised' should include the 7-valent pneumococcal conjugate and meningococcal C vaccines, and wider dissemination should be considered.

NSW Annual Immunisation Coverage Report, 2009.

AIMS: This is the first in a series of annual immunisation coverage reports that document trends in NSW for a range of standard measures derived from Australian Childhood Immunisation Register data, including overall coverage at standard age milestones and for individual vaccines. This report includes data up to and including 2009. METHODS: Data from the Australian Childhood Immunisation Register, the NSW Health Survey and the NSW School Immunisation Program were used to calculate various measures of population coverage relating to childhood vaccines, adult influenza and pneumococcal vaccines and adolescent vaccination, respectively. RESULTS: Immunise Australia Program targets have been reached for children at 12 and 24 months of age but not for children at 5 years of age. Delayed receipt of vaccines is an issue for vaccines recommended for Aboriginal children. Pneumococcal vaccination in the elderly has been steadily rising, although it has remained lower than the influenza coverage estimates. For adolescents, there is better coverage for the first and second doses of human papillomavirus vaccine and the dose of dTpa than for varicella. CONCLUSION: This comprehensive analysis provides important baseline data for NSW against which future reports can be compared to monitor progress in improving immunisation coverage. Immunisation at the earliest appropriate age should be a public health goal for countries such as Australia where high levels of vaccine coverage at milestone ages have been achieved.

Vaccine preventable diseases and vaccination policy for indigenous populations.

There are many similarities regarding the health status of Indigenous people in the 4 English-speaking developed countries of North America and the Pacific (United States, Canada, Australia, New Zealand), where they are all now minority populations. Although vaccines have contributed to the reduction or elimination of disease disparities for many infections, Indigenous people continue to have higher morbidity and mortality from many chronic and infectious diseases compared with the general populations in their countries. This review summarizes the available data on the epidemiology of vaccine-preventable diseases in Indigenous populations in these 4 countries in the context of the vaccination strategies used and their impact, with the aim of identifying successful strategies with the potential for wider implementation.

How reliable are Australian Childhood Immunisation Register coverage estimates for indigenous children? An assessment of data quality and coverage.

Low levels of reporting indigenous status to the Australian Childhood Immunisation Register (ACIR) in the past have resulted in reduced confidence in vaccination coverage data for Aboriginal and Torres Straight Islander children. This study shows that the reporting of indigenous status has improved from 42% of the estimated national cohort of Indigenous children aged 12 to 14 months in 2002 to 95% in 2005. Over that period diphtheria-tetanus-pertussis (DTP) vaccination coverage estimates for Indigenous children increased slightly from 86.0% to 86.9%. Data by state and territory or remoteness are also presented. ACIR vaccination coverage estimates for Indigenous children can now be used with confidence for program planning at the national and jurisdictional level.