apyrase and Acute-Kidney-Injury

ATP and its ultimate degradation product adenosine are potent extracellular signalling molecules that elicit a variety of pathophysiological functions in the kidney through the activation of P2 and P1 purinergic receptors, respectively. Extracellular purines can modulate immune responses, balancing inflammatory processes and immunosuppression; indeed, alterations in extracellular nucleotide and adenosine signalling determine outcomes of inflammation and healing processes. The functional activities of ectonucleotidases such as CD39 and CD73, which hydrolyse pro-inflammatory ATP to generate immunosuppressive adenosine, are therefore pivotal in acute inflammation. Protracted inflammation may result in aberrant adenosinergic signalling, which serves to sustain inflammasome activation and worsen fibrotic reactions. Alterations in the expression of ectonucleotidases on various immune cells, such as regulatory T cells and macrophages, as well as components of the renal vasculature, control purinergic receptor-mediated effects on target tissues within the kidney. The role of CD39 as a rheostat that can have an impact on purinergic signalling in both acute and chronic inflammation is increasingly supported by the literature, as detailed in this Review. Better understanding of these purinergic processes and development of novel drugs targeting these pathways could lead to effective therapies for the management of acute and chronic kidney disease.

Topics: 5'-Nucleotidase; Acute Kidney Injury; Adenosine; Adenosine Triphosphate; Animals; Antigens, CD; Apyrase; Carcinoma, Renal Cell; Diabetic Nephropathies; Graft Rejection; Humans; Immune Tolerance; Inflammation; Kidney Diseases; Kidney Neoplasms; Kidney Transplantation; Macrophages; Polycystic Kidney Diseases; Receptors, Purinergic P1; Receptors, Purinergic P2; Renal Insufficiency, Chronic; Reperfusion Injury; Signal Transduction; T-Lymphocytes, Regulatory

Unfettered inflammation is a leading cause of multiple organ failures in sepsis. The anti‑inflammatory role of cluster of differentiation (CD)39 has been previously reported. The present study aimed to investigate the role of unfettered inflammation in sepsis‑induced acute kidney injury (AKI). Lipopolysaccharide (LPS) was introduced to construct a sepsis mouse model. Kidney function and pathological changes in mice were measured at 12, 24 and 48 h. CD39 overexpression and inhibition vectors were transfected into renal tubular epithelial (HK‑2) cells, followed by LPS treatment (10 µg/ml), and the cell viability changes at 24 h after treatment were assessed and the expression of NLR family pyrin domain containing 3 (NLRP3), cleaved caspase‑1 and CD39 were determined by performing ELISAs. Cell apoptosis and reactive oxygen species (ROS) levels were determined by flow cytometry. It was found that after LPS administration, kidney injury was the most serious at 24 h in mice. CD39 overexpression could suppress the upregulation of pro‑inflammatory cytokines induced by LPS treatment. In addition, the cell apoptosis and ROS level exhibited an obvious decrease, while cell viability increased. The NLRP3 expression and activity also showed a great inhibition in CD39‑overexpressed cells. By contrast to CD39 overexpression, CD39 inhibition promoted the activation of the NLRP3 inflammasome. These data indicate the protective role of CD39 in LPS‑induced renal tubular epithelial cell damage through inhibiting NLRP3 inflammasome activation and that CD39 might be a potential therapeutic target in sepsis‑induced AKI.

Topics: Acute Kidney Injury; Animals; Antigens, CD; Apoptosis; Apyrase; Cell Survival; Cytokines; Disease Models, Animal; Epithelial Cells; Inflammasomes; Inflammation; Kidney Tubules; Male; Mice; Mice, Inbred C57BL; NLR Family, Pyrin Domain-Containing 3 Protein; Reactive Oxygen Species; Sepsis; Signal Transduction

Renal ischemia-reperfusion injury (IRI) leads to acute kidney injury and renal fibrosis. CD39 is a key purinergic enzyme in the hydrolysis of adenosine triphosphate (ATP) and increased CD39 enzymatic activity protects from acute IRI but its effect on renal fibrosis is not known.. Using a mouse model of unilateral renal IRI, the effects of increased CD39 activity (using soluble apyrase and mice expressing human CD39 transgene) on acute and chronic renal outcomes were examined. Nucleotide (ATP, adenosine diphosphate, adenosine monophosphate) and nucleoside (adenosine and inosine) levels were quantified by high-performance liquid chromatography. Soluble apyrase reduced acute renal injury at 24 hours and renal fibrosis at 4 weeks post-IRI, compared with vehicle-treated mice.. Soluble apyrase reduced renal ATP, adenosine diphosphate, and adenosine monophosphate, but not adenosine levels, during ischemia. In comparison with wild-type littermates, hCD39 transgenic mice were protected from acute renal injury at 24 hours, but had increased renal fibrosis at 4 weeks post-IRI. hCD39 transgene expression was localized to the vascular endothelium at baseline and did not affect total renal nucleotide and nucleoside levels during ischemia. However, hCD39 transgene was more widespread at 4 weeks post-IRI and was associated with higher renal adenosine levels at 4 weeks post-IRI compared with wild-type littermates.. A single dose of apyrase administration before IRI protects from both acute and chronic renal injuries and may have clinical application in protection from ischemic-induced renal injury. Furthermore, transgenic expression of hCD39 is associated with increased renal fibrosis after ischemia.

Topics: Acute Kidney Injury; Adenine Nucleotides; Animals; Antigens, CD; Apyrase; Chronic Disease; Disease Models, Animal; Enzyme Induction; Enzyme Inhibitors; Fibrosis; Genetic Predisposition to Disease; Humans; Hydrolysis; Kidney; Male; Mice, Inbred C57BL; Mice, Transgenic; Phenotype; Receptors, Adrenergic, beta-2; Reperfusion Injury; RNA, Messenger; Time Factors

Previous studies showed increased extracellular nucleotides during renal ischemia-reperfusion. While nucleotides represent the main source for extracellular adenosine and adenosine signaling contributes to renal protection from ischemia, we hypothesized a role for ecto-nucleoside-triphosphate-diphosphohydrolases (E-NTPDases) in renal protection. We used a model of murine ischemia-reperfusion and in situ ischemic preconditioning (IP) via a hanging weight system for atraumatic renal artery occlusion. Initial studies with a nonspecific inhibitor of E-NTPDases (POM-1) revealed inhibition of renal protection by IP. We next pursued transcriptional responses of E-NTPDases (E-NTPDase1-3, and 8) to renal IP, and found a robust and selective induction of E-NTPDase1/CD39 transcript and protein. Moreover, based on clearance studies, plasma electrolytes, and renal tubular histology, IP protection was abolished in gene-targeted mice for cd39 whereas increased renal adenosine content with IP was attenuated. Furthermore, administration of apyrase reconstituted renal protection by IP in cd39-/- mice. Finally, apyrase treatment of wild-type mice resulted in increased renal adenosine concentrations and a similar degree of renal protection from ischemia as IP treatment. Taken together, these data identify CD39-dependent nucleotide phosphohydrolysis in renal protection. Moreover, the present studies suggest apyrase treatment as a novel pharmacological approach to renal diseases precipitated by limited oxygen availability.

Topics: Acute Kidney Injury; Adenosine; Animals; Antigens, CD; Apyrase; Female; Ischemic Preconditioning; Kidney; Kidney Function Tests; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Renal Artery; Renal Circulation; Reperfusion Injury