Genetic potential for an acute inflammatory response in IgA glomerulonephritis in mice

Mice selected on the basis of an acute inflammatory response (AIR) can provide information about the immunopathological mechanisms of glomerulonephritis. We studied the differences between mice selected for a maximal AIR (AIRmax that attract more polymorphonuclear cells to the site of injury) or a minimal AIR (AIRmin that attract more mononuclear cells) in an experimental model of IgA nephropathy in order to investigate the effect of genetic background on glomerular disease progression and the participation of the monocyte chemoattractant protein-1 (MCP-1) chemokine. IgA nephropathy was induced by intraperitoneal ovalbumin injection and bile duct ligation in AIRmax and AIRmin mice. Histological changes, urinary protein/creatinine ratio, serum IgA levels, immunofluorescence for IgA, IgG and complement C3 fraction, immunohistochemistry for macrophages and MCP-1, and MCP-1 levels in macerated kidney were determined. Mesangial IgA deposition was seen only in AIRmin mice, which presented more renal lesions. Increased serum IgA levels (1.5 ± 0.4 vs 0.3 ± 0.1 mg/mL, P < 0.001), high glomerular MCP-1 expression and decreased monocyte/macrophage infiltration in the interstitial area (0.3 ± 0.3 vs 1.1 ± 0.9 macrophages/field, P < 0.05) were detected in AIRmin mice compared to AIRmax mice. No glomerular monocyte/macrophage infiltration was detected in either strain. In spite of the absence of IgA deposition, AIRmax mice presented discrete or absent mesangial proliferation. The study showed that there are differences between mice selected for AIRmax and AIRmin with respect to serum IgA levels, histological damage and MCP-1 chemokine production after ovalbumin injection in combination with bile duct ligation.

Impact of initial exposure to calcineurin inhibitors on kidney graft function of patients at high risk to develop delayed graft function

We conducted a retrospective analysis of the influence of full doses of calcineurin inhibitors [8-10 mg kg-1 day-1 cyclosporine (N = 80), or 0.2-0.3 mg kg-1 day-1 tacrolimus (N = 68)] administered from day 1 after transplantation on the transplant outcomes of a high-risk population. Induction therapy was used in 13% of the patients. Patients also received azathioprine (2 mg kg-1 day-1, N = 58) or mycophenolate mofetil (2 g/day, N = 90), and prednisone (0.5 mg kg-1 day-1, N = 148). Mean time on dialysis was 79 ± 41 months, 12% of the cases were re-transplants, and 21% had panel reactive antibodies >10%. In 43% of donors the cause of death was cerebrovascular disease and 27% showed creatinine above 1.5 mg/dL. The incidence of slow graft function (SGF) and delayed graft function (DGF) was 15 and 60%, respectively. Mean time to last dialysis and to nadir creatinine were 18 ± 15 and 34 ± 20 days, respectively. Mean creatinine at 1 year after transplantation was 1.48 ± 0.50 mg/dL (DGF 1.68 ± 0.65 vs SGF 1.67 ± 0.66 vs immediate graft function (IGF) 1.41 ± 0.40 mg/dL, P = 0.089). The incidence of biopsy-confirmed acute rejection was 22% (DGF 31%, SGF 10%, IGF 8%). One-year patient and graft survival was 92.6 and 78.4%, respectively. The incidence of cytomegalovirus disease, post-transplant diabetes mellitus and malignancies was 28, 8.1, and 0%, respectively. Compared to previous studies, the use of initial full doses of calcineurin inhibitors without antibody induction in patients with SGF or DGF had no negative impact on patient and graft survival.

Renal and extrarenal manifestations of autosomal dominant polycystic kidney disease

The objective of the present study was to determine the frequency of the most common clinical features in patients with autosomal dominant polycystic kidney disease in a sample of the Brazilian population. The medical records of 92 patients with autosomal dominant polycystic kidney disease attended during the period from 1985 to 2003 were reviewed. The following data were recorded: age at diagnosis, gender, associated clinical manifestations, occurrence of stroke, age at loss of renal function (beginning of dialysis), and presence of a family history. The involvement of abdominal viscera was investigated by ultrasonography. Intracranial alterations were prospectively investigated by magnetic resonance angiography in 42 asymptomatic patients, and complemented with digital subtraction arteriography when indicated. Mean age at diagnosis was 35.1 ± 14.9 years, and mean serum creatinine at referral was 2.4 ± 2.8 mg/dL. The most frequent clinical manifestations during the disease were arterial hypertension (63.3%), lumbar pain (55.4%), an abdominal mass (47.8%), and urinary infection (35.8%). Loss of renal function occurred in 27 patients (mean age: 45.4 ± 9.5 years). The liver was the second organ most frequently affected (39.1%). Stroke occurred in 7.6% of the patients. Asymptomatic intracranial aneurysm was detected in 3 patients and arachnoid cysts in 3 other patients. In conclusion, the most common clinical features were lumbar pain, arterial hypertension, abdominal mass, and urinary infection, and the most serious complications were chronic renal failure and stroke. Both intracranial aneurysms and arachnoid cysts occurred in asymptomatic patients at a frequency of 7.14%.

Increased expression of p38 mitogen- activated protein kinase is related to the acute renal lesions induced by gentamicin

Mitogen-activated protein kinases (MAPK) may be involved in the pathogenesis of acute renal failure. This study investigated the expression of p-p38 MAPK and nuclear factor kappa B (NF-kappaB) in the renal cortex of rats treated with gentamicin. Twenty rats were injected with gentamicin, 40 mg/kg, im, twice a day for 9 days, 20 with gentamicin + pyrrolidine dithiocarbamate (PDTC, an NF-kappaB inhibitor), 14 with 0.15 M NaCl, im, twice a day for 9 days, and 14 with 0.15 M NaCl , im, twice a day for 9 days and PDTC, 50 mg kg-1 day-1, ip, twice a day for 15 days. The animals were killed 5 and 30 days after the last of the injections and the kidneys were removed for histological, immunohistochemical and Western blot analysis and for nitrate determination. The results of the immunohistochemical study were evaluated by counting the p-p38 MAPK-positive cells per area of renal cortex measuring 0.05 mm². Creatinine was measured by the Jaffé method in blood samples collected 5 and 30 days after the end of the treatments. Gentamicin-treated rats presented a transitory increase in plasma creatinine levels. In addition, animals killed 5 days after the end of gentamicin treatment presented acute tubular necrosis and increased nitrate levels in the renal cortex. Increased expression of p-p38 MAPK and NF-kappaB was also observed in the kidneys from these animals. The animals killed 30 days after gentamicin treatment showed residual areas of interstitial fibrosis in the renal cortex, although the expression of p-p38 MAPK in their kidneys did not differ from control. Treatment with PDTC reduced the functional and structural changes induced by gentamicin as well as the expression of p-p38 MAPK and NF-kappaB. The increased expression of p-p38 MAPK and NF-kappaB observed in these rats suggests that these signaling molecules may be involved in the pathogenesis of tubulointerstitial nephritis induced by gentamicin.

Translational models of coronary artery disease, myocardial infarction and heart failure. Development, validation and in vivo imaging studies using positron emission tomography

Coronary artery disease is an atherosclerotic disease, which leads to narrowing of coronary arteries, deteriorated myocardial blood flow and myocardial ischaemia. In acute myocardial infarction, a prolonged period of myocardial ischaemia leads to myocardial necrosis. Necrotic myocardium is replaced with scar tissue. Myocardial infarction results in various changes in cardiac structure and function over time that results in “adverse remodelling”. This remodelling may result in a progressive worsening of cardiac function and development of chronic heart failure. In this thesis, we developed and validated three different large animal models of coronary artery disease, myocardial ischaemia and infarction for translational studies. In the first study the coronary artery disease model had both induced diabetes and hypercholesterolemia. In the second study myocardial ischaemia and infarction were caused by a surgical method and in the third study by catheterisation. For model characterisation, we used non-invasive positron emission tomography (PET) methods for measurement of myocardial perfusion, oxidative metabolism and glucose utilisation. Additionally, cardiac function was measured by echocardiography and computed tomography. To study the metabolic changes that occur during atherosclerosis, a hypercholesterolemic and diabetic model was used with [18F] fluorodeoxyglucose ([18F]FDG) PET-imaging technology. Coronary occlusion models were used to evaluate metabolic and structural changes in the heart and the cardioprotective effects of levosimendan during post-infarction cardiac remodelling. Large animal models were used in testing of novel radiopharmaceuticals for myocardial perfusion imaging. In the coronary artery disease model, we observed atherosclerotic lesions that were associated with focally increased [18F]FDG uptake. In heart failure models, chronic myocardial infarction led to the worsening of systolic function, cardiac remodelling and decreased efficiency of cardiac pumping function. Levosimendan therapy reduced post-infarction myocardial infarct size and improved cardiac function. The novel 68Ga-labeled radiopharmaceuticals tested in this study were not successful for the determination of myocardial blood flow. In conclusion, diabetes and hypercholesterolemia lead to the development of early phase atherosclerotic lesions. Coronary artery occlusion produced considerable myocardial ischaemia and later infarction following myocardial remodelling. The experimental models evaluated in these studies will enable further studies concerning disease mechanisms, new radiopharmaceuticals and interventions in coronary artery disease and heart failure.

Incidence of heart failure in infarcted rats that die spontaneously

The present study reports for the first time the incidence of congestive heart failure (CHF) in previously infarcted rats that died spontaneously. Previously, pulmonary (PWC) and hepatic (HWC) water contents were determined in normal rats: 14 control animals were evaluated immediately after sacrifice, 8 placed in a refrigerator for 24 h, and 10 left at room temperature for 24 h. In the infarcted group, 9 rats died before (acute) and 28 died 48 h after (chronic) myocardial infarction. Thirteen chronic animals were submitted only to autopsy (N = 13), whereas PWC and HWC were also determined in the others (N = 15). Seven rats survived 48 h and died during anesthesia. Notably, PWC differed in normal rats: ambient (75.7 ± 1.3%) < control (77.5 ± 0.7%) < refrigerator (79.1 ± 1.4%) and there were no differences with respect to HWC. No clinical signs of CHF (dyspnea, lethargy or foot edema) were observed in infarcted rats before death. PWC was elevated in all chronic and anesthetized rats. HWC was increased in 48% of chronic and in all anesthetized rats. Our data showed that PWC needs to be evaluated before 24 h post mortem and that CHF is the rule in chronic infarcted rats suffering natural death. The congestive syndrome cannot be diagnosed correctly in rats by clinical signs alone, as previously proposed.

Glycyrrhizin attenuates endotoxin- induced acute liver injury after partial hepatectomy in rats

Massive hepatectomy associated with infection induces liver dysfunction, or even multiple organ failure and death. Glycyrrhizin has been shown to exhibit anti-oxidant and anti-inflammatory activities. The aim of the present study was to investigate whether glycyrrhizin could attenuate endotoxin-induced acute liver injury after partial hepatectomy. Male Wistar rats (6 to 8 weeks old, weighing 200-250 g) were randomly assigned to three groups of 24 rats each: sham, saline and glycyrrhizin. Rats were injected intravenously with lipopolysaccharide (LPS) 24 h after 70% hepatectomy. Glycyrrhizin, pre-administered three times with 24 h intervals 48 h before hepatectomy, prolonged the survival of rats submitted to partial hepatectomy and LPS injection, compared with saline controls. Glycyrrhizin was shown to attenuate histological hepatic changes and significantly reduced serum levels of aspartate aminotransferase, alanine aminotransferase, and lactic dehydrogenase, at all the indicated times (6 rats from each were sacrificed 1, 3, 6, and 9 h after LPS injection), compared with saline controls. Glycyrrhizin also significantly inhibited hepatocyte apoptosis by down-regulating the expression of caspase-3 and inhibiting the release of cytochrome C from mitochondria into the cytoplasm. The anti-inflammatory activity of glycyrrhizin may rely on the inhibition of release of tumor necrosis factor-a, myeloperoxidase activity, and translocation of nuclear factor-kappa B into the nuclei. Glycyrrhizin also up-regulated the expression of proliferating cell nuclear antigen, implying that it might be able to promote regeneration of livers harmed by LPS. In summary, glycyrrhizin may represent a potent drug protecting the liver against endotoxin-induced injury, especially after massive hepatectomy.

The role of stress-activated protein kinase signaling in renal pathophysiology

Two major stress-activated protein kinases are the p38 mitogen-activated protein kinase (MAPK) and the c-Jun amino terminal kinase (JNK). p38 and JNK are widely expressed in different cell types in various tissues and can be activated by a diverse range of stimuli. Signaling through p38 and JNK is critical for embryonic development. In adult kidney, p38 and JNK signaling is evident in a restricted pattern suggesting a normal physiological role. Marked activation of both p38 and JNK pathways occurs in human renal disease, including glomerulonephritis, diabetic nephropathy and acute renal failure. Administration of small molecule inhibitors of p38 and JNK has been shown to provide protection from renal injury in different types of experimental kidney disease through inhibition of renal inflammation, fibrosis, and apoptosis. In particular, a role for JNK signaling has been identified in macrophage activation resulting in up-regulation of pro-inflammatory mediators and the induction of renal injury. The ability to provide renal protection by blocking either p38 or JNK indicates a lack of redundancy for these two signaling pathways despite their activation by common stimuli. Therefore, the stress-activated protein kinases, p38 and JNK, are promising candidates for therapeutic intervention in human renal diseases.

Glomerular filtration is reduced by high tidal volume ventilation in an in vivo healthy rat model

Mechanical ventilation has been associated with organ failure in patients with acute respiratory distress syndrome. The present study examines the effects of tidal volume (V T) on renal function using two V T values (8 and 27 mL/kg) in anesthetized, paralyzed and mechanically ventilated male Wistar rats. Animals were randomized into two groups of 6 rats each: V T8 (V T, 8 mL/kg; 61.50 ± 0.92 breaths/min; positive end-expiratory pressure, 3.0 cmH2O; peak airway pressure (PAW), 11.8 ± 2.0 cmH2O), and V T27 (V T, 27 mL/kg; 33.60 ± 1.56 breaths/min; positive end-expiratory pressure, none, and PAW, 22.7 ± 4.0 cmH2O). Throughout the experiment, mean PAW remained comparable between the two groups (6.33 ± 0.21 vs 6.50 ± 0.22 cmH2O). For rats in the V T27 group, inulin clearance (mL·min-1·body weight-1) decreased acutely after 60 min of mechanical ventilation and even more significantly after 90 min, compared with baseline values (0.60 ± 0.05 and 0.45 ± 0.05 vs 0.95 ± 0.07; P < 0.001), although there were no differences between groups in mean arterial pressure or gasometric variables. In the V T8 group, inulin clearance at 120 min of mechanical ventilation remained unchanged in relation to baseline values (0.72 ± 0.03 vs 0.80 ± 0.05). The V T8 and V T27 groups did not differ in terms of serum thiobarbituric acid reactive substances (3.97 ± 0.27 vs 4.02 ± 0.45 nmol/mL) or endothelial nitric oxide synthase expression (94.25 ± 2.75 vs 96.25 ± 2.39%). Our results show that glomerular filtration is acutely affected by high tidal volume ventilation but do not provide information about the mechanism.

Effect of castration on renal glycosaminoglycans and their urinary excretion in male and female rats with chronic renal failure

Glycosaminoglycans (GAGs) participate in a variety of processes in the kidney, and evidence suggests that gender-related hormones participate in renal function. The aim of this study was to analyze the relationship of GAGs, gender, and proteinuria in male and female rats with chronic renal failure (CRF). GAGs were analyzed in total kidney tissue and 24-h urine of castrated (c), male (M), and female (F) Wistar control (C) rats (CM, CMc, CF, CFc) and after 30 days of CRF induced by 5/6 nephrectomy (CRFM, CRFMc, CRFF, CRFFc). Total GAG quantification and composition were determined using agarose and polyacrylamide gel electrophoresis, respectively. Renal GAGs were higher in CF compared to CM. CRFM presented an increase in renal GAGs, heparan sulfate (HS), and proteinuria, while castration reduced these parameters. However, CRFF and CRFFc groups showed a decrease in renal GAGs concomitant with an increase in proteinuria. Our results suggest that, in CRFM, sex hormones quantitatively alter GAGs, mainly HS, and possibly the glomerular filtration barrier, leading to proteinuria. The lack of this response in CRFMc, where HS did not increase, corroborates this theory. This pattern was not observed in females. Further studies of CRF are needed to clarify gender-dependent differences in HS synthesis.

Pulmonary hypertension due to acute respiratory distress syndrome

Our aims were to describe the prevalence of pulmonary hypertension in patients with acute respiratory distress syndrome (ARDS), to characterize their hemodynamic cardiopulmonary profiles, and to correlate these parameters with outcome. All consecutive patients over 16 years of age who were in the intensive care unit with a diagnosis of ARDS and an in situ pulmonary artery catheter for hemodynamic monitoring were studied. Pulmonary hypertension was diagnosed when the mean pulmonary artery pressure was >25 mmHg at rest with a pulmonary artery occlusion pressure or left atrial pressure <15 mmHg. During the study period, 30 of 402 critically ill patients (7.46%) who were admitted to the ICU fulfilled the criteria for ARDS. Of the 30 patients with ARDS, 14 met the criteria for pulmonary hypertension, a prevalence of 46.6% (95% CI; 28-66%). The most common cause of ARDS was pneumonia (56.3%). The overall mortality was 36.6% and was similar in patients with and without pulmonary hypertension. Differences in patients' hemodynamic profiles were influenced by the presence of pulmonary hypertension. The levels of positive end-expiratory pressure and peak pressure were higher in patients with pulmonary hypertension, and the PaCO2 was higher in those who died. The level of airway pressure seemed to influence the onset of pulmonary hypertension. Survival was determined by the severity of organ failure at admission to the intensive care unit.

Hydrogen sulfide in posthemorrhagic shock mesenteric lymph drainage alleviates kidney injury in rats

Posthemorrhagic shock mesenteric lymph (PHSML) is a key factor in multiple organ injury following hemorrhagic shock. We investigated the role of hydrogen sulfide (H2S) in PHSML drainage in alleviating acute kidney injury (AKI) by administering D,L-propargylglycine (PPG) and sodium hydrosulfide hydrate (NaHS) to 12 specific pathogen-free male Wistar rats with PHSML drainage. A hemorrhagic shock model was established in 4 experimental groups: shock, shock+drainage, shock+drainage+PPG (45 mg/kg, 0.5 h prehemorrhage), and shock+drainage+NaHS (28 µmol/kg, 0.5 h prehemorrhage). Fluid resuscitation was performed after 1 h of hypotension, and PHMSL was drained in the last three groups for 3 h after resuscitation. Renal function and histomorphology were assessed along with levels of H2S, cystathionine-γ-lyase (CSE), Toll-like receptor 4 (TLR4), interleukin (IL)-10, IL-12, and tumor necrosis factor (TNF)-α in renal tissue. Hemorrhagic shock induced AKI with increased urea and creatinine levels in plasma and higher H2S, CSE, TLR4, IL-10, IL-12, and TNF-α levels in renal tissue. PHSML drainage significantly reduced urea, creatinine, H2S, CSE, and TNF-α but not TLR4, IL-10, or IL-12. PPG decreased creatinine, H2S, IL-10, and TNF-α levels, but this effect was reversed by NaHS administration. In conclusion, PHSML drainage alleviated AKI following hemorrhagic shock by preventing increases in H2S and H2S-mediated inflammation.

Prognostic effect of high-flux hemodialysis in patients with chronic kidney disease

We investigated the prognostic effects of high-flux hemodialysis (HFHD) and low-flux hemodialysis (LFHD) in patients with chronic kidney disease (CKD). Both an electronic and a manual search were performed based on our rigorous inclusion and exclusion criteria to retrieve high-quality, relevant clinical studies from various scientific literature databases. Comprehensive meta-analysis 2.0 (CMA 2.0) was used for the quantitative analysis. We initially retrieved 227 studies from the database search. Following a multi-step screening process, eight high-quality studies were selected for our meta-analysis. These eight studies included 4967 patients with CKD (2416 patients in the HFHD group, 2551 patients in the LFHD group). The results of our meta-analysis showed that the all-cause death rate in the HFHD group was significantly lower than that in the LFHD group (OR=0.704, 95%CI=0.533-0.929, P=0.013). Additionally, the cardiovascular death rate in the HFHD group was significantly lower than that in the LFHD group (OR=0.731, 95%CI=0.616-0.866, P<0.001). The results of this meta-analysis clearly showed that HFHD decreases all-cause death and cardiovascular death rates in patients with CKD and that HFHD can therefore be implemented as one of the first therapy choices for CKD.

Acute but not chronic metabolic acidosis potentiates the acetylcholine-induced reduction in blood pressure: an endothelium-dependent effect

Metabolic acidosis has profound effects on vascular tone. This study investigated the in vivo effects of acute metabolic acidosis (AMA) and chronic metabolic acidosis (CMA) on hemodynamic parameters and endothelial function. CMA was induced by ad libitum intake of 1% NH4Cl for 7 days, and AMA was induced by a 3-h infusion of 6 M NH4Cl (1 mL/kg, diluted 1:10). Phenylephrine (Phe) and acetylcholine (Ach) dose-response curves were performed by venous infusion with simultaneous venous and arterial blood pressure monitoring. Plasma nitrite/nitrate (NOx) was measured by chemiluminescence. The CMA group had a blood pH of 7.15±0.03, which was associated with reduced bicarbonate (13.8±0.98 mmol/L) and no change in the partial pressure of arterial carbon dioxide (PaCO2). The AMA group had a pH of 7.20±0.01, which was associated with decreases in bicarbonate (10.8±0.54 mmol/L) and PaCO2 (47.8±2.54 to 23.2±0.74 mmHg) and accompanied by hyperventilation. Phe or ACh infusion did not affect arterial or venous blood pressure in the CMA group. However, the ACh infusion decreased the arterial blood pressure (ΔBP: -28.0±2.35 mm Hg [AMA] to -4.5±2.89 mmHg [control]) in the AMA group. Plasma NOx was normal after CMA but increased after AMA (25.3±0.88 to 31.3±0.54 μM). These results indicate that AMA, but not CMA, potentiated the Ach-induced decrease in blood pressure and led to an increase in plasma NOx, reinforcing the effect of pH imbalance on vascular tone and blood pressure control.

Averting the legacy of kidney disease - focus on childhood

World Kidney Day 2016 focuses on kidney disease in childhood and the antecedents of adult kidney disease that can begin in earliest childhood. Chronic kidney disease (CKD) in childhood differs from that in adults, in that the largest diagnostic group among children includes congenital anomalies and inherited disorders, with glomerulopathies and kidney disease as a consequence of diabetes being relatively uncommon. In addition, many children with acute kidney injury will ultimately develop sequelae that may lead to hypertension and CKD in later childhood or in adult life. Children born early or who are small-for-date newborns have relatively increased risk for the development of CKD later in life. Persons with a high-risk birth and early childhood history should be watched closely in order to help detect early signs of kidney disease in time to provide effective prevention or treatment. Successful therapy is feasible for advanced CKD in childhood; there is evidence that children fare better than adults, if they receive kidney replacement therapy including dialysis and transplantation, although only a minority of children may require this ultimate intervention. Because there are disparities in access to care, effort is needed so that children with kidney disease, wherever they live, may be treated effectively, irrespective of their geographic or economic circumstances. Our hope is that the World Kidney Day will inform the general public, policy makers and caregivers about the needs and possibilities surrounding kidney disease in childhood.