Kidney injury enhances renal G-CSF expression and modulates granulopoiesis and human neutrophil CD177 in vivo.

Kidney injury significantly increases overall mortality. Neutrophilic granulocytes (neutrophils) are the most abundant human blood leukocytes. They are characterized by a high turnover rate, chiefly controlled by granulocyte colony stimulating factor (G-CSF). The role of kidney injury and uremia in regulation of granulopoiesis has not been reported. Kidney transplantation, which inherently causes ischemia-reperfusion injury of the graft, elevated human neutrophil expression of the surface glycoprotein CD177. CD177 is among the most G-CSF-responsive neutrophil genes and reversibly increased on neutrophils of healthy donors who received recombinant G-CSF. In kidney graft recipients, a transient rise in neutrophil CD177 correlated with renal tubular epithelial G-CSF expression. In contrast, CD177 was unaltered in patients with chronic renal impairment and independent of renal replacement therapy. Under controlled conditions of experimental ischemia-reperfusion and unilateral ureteral obstruction injuries in mice, renal G-CSF mRNA and protein expression significantly increased and systemic neutrophilia developed. Human renal tubular epithelial cell G-CSF expression was promoted by hypoxia and proinflammatory cytokine interleukin 17A in vitro. Clinically, recipients of ABO blood group-incompatible kidney grafts developed a larger rise in neutrophil CD177. Their grafts are characterized by complement C4d deposition on the renal endothelium, even in the absence of rejection. Indeed, complement activation, but not hypoxia, induced primary human endothelial cell G-CSF expression. Our data demonstrate that kidney injury induces renal G-CSF expression and modulates granulopoiesis. They delineate differential G-CSF regulation in renal epithelium and endothelium. Altered granulopoiesis may contribute to the systemic impact of kidney injury.

Donor treatment with a PHD-inhibitor activating HIFs prevents graft injury and prolongs survival in an allogenic kidney transplant model.

Long-term survival of renal allografts depends on the chronic immune response and is probably influenced by the initial injury caused by ischemia and reperfusion. Hypoxia-inducible transcription factors (HIFs) are essential for adaptation to low oxygen. Normoxic inactivation of HIFs is regulated by oxygen-dependent hydroxylation of specific prolyl-residues by prolyl-hydroxylases (PHDs). Pharmacological inhibition of PHDs results in HIF accumulation with subsequent activation of tissue-protective genes. We examined the effect of donor treatment with a specific PHD inhibitor (FG-4497) on graft function in the Fisher-Lewis rat model of allogenic kidney transplantation (KTx). Orthotopic transplantation of the left donor kidney was performed after 24 h of cold storage. The right kidney was removed at the time of KTx (acute model) or at day 10 (chronic model). Donor animals received a single dose of FG-4497 (40 mg/kg i.v.) or vehicle 6 h before donor nephrectomy. Recipients were followed up for 10 days (acute model) or 24 weeks (chronic model). Donor preconditioning with FG-4497 resulted in HIF accumulation and induction of HIF target genes, which persisted beyond cold storage. It reduced acute renal injury (serum creatinine at day 10: 0.66 +/- 0.20 vs. 1.49 +/- 1.36 mg/dL; P < 0.05) and early mortality in the acute model and improved long-term survival of recipient animals in the chronic model (mortality at 24 weeks: 3 of 16 vs. 7 of 13 vehicle-treated animals; P < 0.05). In conclusion, pretreatment of organ donors with FG-4497 improves short- and long-term outcomes after allogenic KTx. Inhibition of PHDs appears to be an attractive strategy for organ preservation that deserves clinical evaluation.

HIF-1alpha subunit and vasoactive HIF-1-dependent genes are involved in carbon monoxide-induced cerebral hypoxic stress response.

Hypoxia-inducible transcription factor-1 (HIF-1) is the most important component of cellular and molecular adaptive responses to hypoxia. We aimed to analyze effects of systemic hypoxia and CO exposure on the oxygen-regulated alpha-subunit of HIF-1 and HIF-1-dependent vasoactive target genes in rat brain. Brains of adult Sprague-Dawley rats were investigated after incubation for 3 and 12 h under normoxia, hypoxia (8% O(2)) and CO 0.1% (n = 10 per group). Upon 3 h of exposure, hypoxia and CO-induced accumulation of HIF-1alpha protein in brain homogenates assessed by Western blot analysis. In contrast to hypoxia HIF-1alpha signals decreased markedly during 12 h-exposure to CO. By immunohistochemistry, intensive HIF-1alpha-positive staining was found in neurons of the cortex and hippocampus. Cerebral expression of vasoactive target genes adrenomedullin (ADM) and vascular endothelial growth factor (VEGF) showed up-regulation during both hypoxia and CO exposure indicating functional activation of HIF-1. Hypoxia increased ADM (P < 0.05) and VEGF mRNA levels within 3 h (P < 0.01) which persisted up to 12 h of exposure (ADM, P < 0.05; VEGF, P < 0.001). Similarly, CO inhalation led to early up-regulation of VEGF (3 h: P < 0.05; 12 h: P < 0.01), but a more delayed increase of ADM mRNA levels (3 h: n.s., 12 h: P < 0.01). We suggest that CO-induced oxygen deprivation is a potent stimulus to cerebral HIF-1-regulated hypoxic stress responses even though its effects are more transient than exposure to hypoxia.

Immediate recovery of renal function after orthotopic liver transplantation in a patient with hepatorenal syndrome requiring hemodialysis for more than 8 months.

Severe liver dysfunction may lead to impairment of renal function without an underlying renal pathology. This phenomenon is called hepatorenal syndrome (HRS), which is associated with a poor prognosis showing a median survival of less than 2 months if renal replacement therapy is necessary. Liver transplantation is the best therapeutic option to regain renal function, but because of poor survival, these patients often die before transplantation. Herein we report a 37-year-old patient with ethyl-toxic liver cirrhosis who underwent hemodialysis due to HRS type I for more than 8 months. After living donor liver transplantation, diuresis immediately resumed, renal function soon recovered, and intermittent hemodialysis was stopped at 18 days after transplantation. Renal function was stable with a serum creatinine <2 mg/dL during the last 5 years posttransplantation. As far as we know, only a few cases of an anuric patient suffering from HRS have been reported with a survival beyond 8 months and full recovery of renal function after liver transplantation. This underlined that renal replacement therapy in HRS should be considered as a possible bridging method to liver transplantation even for longer periods.

Amelioration of anemia after kidney transplantation in severe secondary oxalosis.

INTRODUCTION: In small bowel disease such as M. Crohn, the intestinal absorption of oxalate is increased. Severe calcium oxalate deposition in multiple organs as consequence of enteric hyperoxaluria may lead to severe organ dysfunction and chronic renal failure. The management of hemodialyzed patients with short bowel syndrome may be associated with vascular access problems and oxalate infiltration of the bone marrow leading to pancytopenia. Although the risk of recurrence of the disease is very high after renal transplantation, it may be the ultimate therapeutic alternative in secondary hyperoxaluria. CASE: Here, we report a patient with enteric oxalosis due to Crohn's disease. He developed end-stage renal disease, erythropoietin-resistant anemia, oxalate infiltration of the bone marrow and severe vascular access problems. Following high-urgency kidney transplantation, daily hemodiafiltration of 3 hours was performed for 2 weeks to increase oxalate clearance. Despite tubular and interstitial deposition of oxalate in the renal transplant, the patient did not require further hemodialysis and the hematocrit levels normalized. DISCUSSION: Early treatment of hyperoxaluria due to short bowel syndrome is essential to prevent renal impairment. Declining renal function leads to a further increase in oxalate accumulation and consecutive oxalate deposition in the bone marrow or in the vascular wall. If alternative treatments such as special diet or daily hemodialysis are insufficient, kidney transplantation may be a therapeutic alternative in severe cases of enteric oxalosis despite a possible recurrence of the disease.

Expression of hypoxia-inducible transcription factors in developing human and rat kidneys.

Early kidney development is associated with the coordinated branching of the renal tubular and vascular system and hypoxia has been proposed to be a major regulatory factor in this process. Under low oxygen levels, the hypoxia-inducible transcription factor (HIF) regulates the expression of genes involved in angiogenesis, erythropoiesis and glycolysis. To investigate the role of HIF in kidney development, we analyzed the temporal and spatial expression of the oxygen regulated HIF-1alpha and -2alpha subunits at different stages of rat and human kidney development. Using double-staining procedures, localization of the HIF target geneproducts vascular endothelial growth factor (VEGF) and endoglin was studied in relation to HIFalpha. In both species, we found marked nuclear expression of HIF-1alpha in medullary and cortical collecting ducts and in glomerular cells. In contrast, HIF-2alpha was expressed in interstitial and peritubular cells podocytes of the more mature glomeruli. After completion of glomerulogenesis and nephrogenesis, HIF-1alpha and -2alpha were no longer detectable. The HIF-target gene VEGF colocalized with HIF-1alpha protein in glomeruli and medullary collecting ducts. HIF-2alpha colocalized with the endothelium-associated angiogenic factor, endoglin. Both HIFalpha isoforms are activated in the developing kidney in a cell-specific and temporally controlled manner, indicating a regulatory role of oxygen tension in nephrogenesis. HIF-1alpha seems to be primarily involved in tubulogenesis and HIF-2alpha in renal vasculogenesis. Both isoforms are found in glomerulogenesis, potentially having synergistic effects.