Complement Modulation of Anti-Aging Factor Klotho in Ischemia/Reperfusion Injury and Delayed Graft Function.

Klotho is an anti-aging factor mainly produced by renal tubular epithelial cells (TEC) with pleiotropic functions. Klotho is down-regulated in acute kidney injury in native kidney; however, the modulation of Klotho in kidney transplantation has not been investigated. In a swine model of ischemia/reperfusion injury (IRI), we observed a remarkable reduction of renal Klotho by 24 h from IRI. Complement inhibition by C1-inhibitor preserved Klotho expression in vivo by abrogating nuclear factor kappa B (NF-kB) signaling. In accordance, complement anaphylotoxin C5a led to a significant down-regulation of Klotho in TEC in vitro that was NF-kB mediated. Analysis of Klotho in kidneys from cadaveric donors demonstrated a significant expression of Klotho in pre-implantation biopsies; however, patients affected by delayed graft function (DGF) showed a profound down-regulation of Klotho compared with patients with early graft function. Quantification of serum Klotho after 2 years from transplantation demonstrated significant lower levels in DGF patients. Our data demonstrated that complement might be pivotal in the down-regulation of Klotho in IRI leading to a permanent deficiency after years from transplantation. Considering the anti-senescence and anti-fibrotic effects of Klotho at renal levels, we hypothesize that this acquired deficiency of Klotho might contribute to DGF-associated chronic allograft dysfunction.

Emotional symptoms, quality of life and cytokine profile in hemodialysis patients.

BACKGROUND: Mental disorders are frequent in hemodialysis (HD) patients. Depression and anxiety along with physical co-morbidity affect quality of life (QOL). Uremia is associated with inflammation and release of cytokines by lymphomonocytes. Inflammatory cytokines are relevant in depression. The aim of this study was to assess the psychological alterations and QOL in HD patients, and to correlate them with pattern of cytokine production. PATIENTS: 30 HD patients and 20 subjects with CKD Stage I-II K-DOQI. Psychometric tests were administered: 1) Hospital Anxiety and Depression Scale (HADS) composed of an anxiety subscale (HADS-A) and a depression subscale (HADS-D); 2) Kidney Disease Quality of Life (KDQOL) modified, including a cognitive function subscale (KDQOL-CF). Whole blood samples collected at beginning of HD session were diluted with RPMI/heparin and incubated for 24 h in presence of lipopolysaccharide (LPS). IL-1Gamma, IL-6, TNF-alpha and IL-10 were assayed on supernatants and results were normalized per number of lymphomonocytes (ng/106 cells). RESULTS: A depressive mood was more frequent in HD patients (50%) than controls (20%, p < 0.0001). No difference for anxiety (HD = 43%, controls = 45%) was observed. QOL score was significantly lower in HD than controls (p = 0.006) and correlated inversely with HADS total, HADS-A and HADS-D (p < 0.0001). Albumin, Kt/V and phosphate were comparable in patients with or without anxiety or depression. Cytokine production was significantly higher in HD patients than controls (IL-1beta p = 0.05; IL-6 p = 0.010; TNF-alpha p < 0.0001; IL-10, p = 0.0019). HD patients with the HADS-A positive for anxiety showed higher IL-6 production (p = 0.026), while IL-1beta levels were not associated with symptoms of depression. KDQOL-CF correlated inversely with levels of IL-6, TNF-alpha and IL-10. CONCLUSIONS: HD patients have symptoms of depression and anxiety that negatively affect QOL. These symptoms are independent of the efficiency of dialysis and nutritional status. On the contrary, IL-6 is linked to the presence of psychological discomfort in these patients.

Platelet-leukocyte interactions in hemodialysis patients: culprit or bystander?

The formation of circulating platelet-leukocyte complexes has been observed in a variety of conditions and may be pathophysiologically significant. Platelet-leukocyte interactions in fact facilitate metabolic cooperation and mutual activation, which may be of relevance in many biological processes including inflammation, atherogenesis and hemostasis. During hemodialysis procedure, the series of reactions that can occur upon blood contact with the foreign membrane surface may involve a variety of changes affecting almost every cellular and plasmatic component of the blood. This article reviews the evidence for abnormal interactions between circulating platelets and leukocytes in uremic patients undergoing maintenance hemodialysis and the pathophysiologic implications which may stem from such interactions.

Clinical relevance of cytokine production in hemodialysis.

Blood-dialyzer interaction in hemodialysis has the potential to activate mononuclear cells leading to the production of inflammatory cytokines. The extent of activation is dependent on the dialyzer material used and is considered an index of biocompatibility. Cytokines, such as interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and IL-6, may induce an inflammatory state and are believed to play a significant role in dialysis-related morbidity. The interleukin hypothesis suggests that the release of proinflammatory cytokines acts as an underlying pathophysiologic event in hemodialysis-related acute manifestations, such as fever and hypotension. Nevertheless, a cytokine overproduction may alter sleep pattern in chronic hemodialyzed patients, thus explaining the presence of sleep disorders in these patients. A potential role of cytokines in chronic-related morbidity has also been suggested. High levels of some inflammatory cytokines are often associated with anemia caused by hyporesponsiveness to erythropoietin. Cytokine production may also play a relevant role in bone remodeling by regulating osteoblast/osteoclast cell functions and parathyroid hormone (PTH). Finally, cytokine release may have a long-term deleterious effect on mortality of uremic patients by altering immune response and increasing susceptibility to infections. Bioincompatibility of dialytic membranes may also contribute to malnutrition in dialysis patients by increasing the monocyte release of catabolic cytokines such as TNF-alpha and IL-6. Bioincompatible dialytic treatment may induce an inappropriate monocyte activation and cytokine production, which, in turn, may mediate some of the immune and metabolic dysfunction associated with hemodialysis. The use of biocompatible dialytic membranes appears to reduce the monocyte activation and to improve the survival of hemodialysis patients.

C5b-9 generation and cytokine production in hemodialyzed patients.

The role of the complement system in the induction of cytokine release is controversial. Plasma terminal C complex C5b-9 along with Bb and C4d fragments were evaluated in 22 patients during routine acetate or bicarbonate hemodialysis using cuprophane membranes and hemodiafiltration (HDF) or acetate-free-biofiltration (AFB) using polyacrylonitrile (PAN) membranes. In a subgroup of six uremic patients we also evaluated the release of tumor necrosis factor (TNF alpha) and interleukin-6 (IL-6) from monocytes before and after six subsequent sessions with bicarbonate-cuprophane, HDF and AFB-PAN. At beginning of the dialysis increased plasma C5b-9 levels were found in patients treated by acetate or bicarbonate-cuprophane. Moreover, a rapid significant (P < 0.001) increase of C5b-9 levels occurred in both groups 15 minutes after the onset of the hemodialysis procedure with a plateau at 180 minutes. In contrast, only a slight increase in the plasma C5b-9 levels was observed in patients dialysed with HDF or AFB using PAN membranes. This increase was more pronounced with HDF at 0 minutes compared with controls. A positive linear correlation was found in all patients between C5b-9 generation and plasma Bb levels at different times in the dialysis session. The production of C4d fragment remained unchanged in all groups, indicating that C5b-9 complex generation is due to the prevalent alternative complement pathway activation. The pattern of cytokine production strictly resembled the complement system activation and C5b-9 generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological significance of the C3 nephritic factor in membranoproliferative glomerulonephritis.

Serum levels of the C3 nephritic factor (C3NeF), an IgG autoantibody directed against the C3bBb convertase of the alternative complement pathway, and of eight complement components (C1q, C4, C3, C3d, C5, C9, fB and properdin) were measured in 109 serum samples from 27 patients with idiopathic membranoproliferative glomerulonephritis (MPGN) (type I, 20 cases, and type II, 7 cases) and 14 patients with secondary MPGN. Correlations between the concentrations of C3NeF, serum complement levels and progression of the renal damage were studied during the course of the disease in 14 patients with C3NeF activity. The results showed that (1) C3NeF activity was more frequent in patients with type II MPGN than in patients with type I disease; nevertheless there was a high incidence of this splitting activity in patients with secondary MPGN, (2) high levels of the complement components were present in patients with MPGN, (3) low levels of C3 occurred frequently in type II disease and in secondary MPGN, (4) there was no correlation between C3, fB and C3NeF levels, (5) the presence of C3NeF was associated with a more rapid deterioration of renal function. Longitudinal studies showed that serum levels of C3NeF were not satisfactory for monitoring the clinical course of the illness and, in this respect, are similar to the levels of other autoantibodies in patients with autoimmune disease. As MPGN is a clinical syndrome with various pathogeneses, we suggest that the autoantibody, C3NeF, should be considered only as a marker of some forms of MPGN.

Influence of different dialyzer membranes on plasma fibronectin levels in hemodialyzed patients.

Plasma fibronectin (FN) was assayed in 30 patients with chronic renal failure under conservative therapy, 60 uremic patients undergoing periodic hemodialysis, and 7 patients treated by hemofiltration. Plasma FN was significantly lower in uremic patients on conservative therapy and in those who received intermittent hemodialysis than in the control group. No difference was seen between mean FN concentrations using different dialyzer membranes. Nevertheless, plasma FN levels were significantly higher in subjects after intermittent hemofiltration. There was no evidence of activation of the coagulation system or of any correlation between FN and fibrinogen values. These findings suggest that conventional hemodialysis is not effective in improving the low levels of plasma FN found in uremic patients, whereas intermittent hemofiltration raises FN. These differences may be due to the fact that during hemofiltration, even when using the same dialyzer membranes as in conventional hemodialysis, some "substances" with high molecular weight that could block the synthesis of FN could be removed.

[Significance of immunocomplexes and complement in renal transplantation. Preliminary data]. / Significato degli immunocomplessi e del complemento nel trapianto renale. Dati preliminari.

The authors have measured circulating immune complexes (ic) and some components (C1q, C4, C3 and properdin factor B) in 87 serum samples obtained during the follow-up of five renal transplantation. Results showed high serum levels of ic with normal renal function of the graft especially in one patient, and an increase of the values in some rejection crises. The behaviour of the complement system was variable for the different components, while frequently low properdin factor B serum levels were noticed in some renal transplantations during the normal function of the graft and during the rejection crisis. In conclusion, the Authors report that a) high levels of ic can be seen also in grafts with normal function and their presence may be correlated with viral infections; b) an increase of ic during the rejection crisis is due to humoral immune response; c) the reduction of C3 and C1q associated to an increase of ic has been frequently seen, and finally; d) the low levels of properdin factor B show a probable intervention of the alternative complement pathway in the rejection crisis.

[The IL-6 soluble receptors in hemodialyzed patients]. / Il ruolo dei recettori solubili dell'interleuchina-6 nei pazienti in trattamento dialitico.

Pro-inflammatory cytokines, in addition to their role in host defence, can be considered a disease mediator; therefore, a reduction in cytokine synthesis or its effects is becoming a target of many diseases. Interleukin-6 (IL-6) is a pro-inflammatory cytokine that could play a role in several clinical problems related to dialysis treatment. Biological activities of IL-6 could be modulated by two soluble circulating receptors, namely sIL-6R and sgp130. sIL-6R can enhance the inflammatory effects of IL-6 and; therefore, is an "agonistically" acting molecule. On the contrary, sgp130 efficiently binds the IL-6/sIL-6R complex with "antagonistic" effects. In this study we evaluated sgp130 release by peripheral blood mononuclear cells (PBMC) harvested from 10 healthy controls (CON) and 11 end-stage renal disease (ESRD) patients undergoing renal dialysis therapy RDT) with cellulosic hemophan membrane (HD). We also evaluated gp130 gene expression by reverse transcriptase polymerase chain reaction (RT-PCR). gp130 is the membrane bound receptor of IL-6 that could be proteolytically cleaved to generate soluble sgp130. Our results demonstrated that HD. at basal conditions, showed a higher release of sgp130 as compared with CON. We also demonstrated by RT-PCR at basal conditions a higher gene expression of gp130 in HD, as compared with CON. These results took place in the absence of any mitogenic stimulation and suggest that in HD patients an inflammatory subclinical status increases sgp130 release. The results obtained after lipopolysaccharide (LPS) stimulation confirm the role of inflammation on the increased release of sgp130 in HD patients.

[Chronic inflammation and cardiovascular risk in hemodialysis]. / Infiammazione cronica e rischio cardiovascolare in emodialisi.

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Traditional risk factors are common in ESRD patients, but they alone may not be sufficient to account for the high prevalence of CVD in this population. Recent clinical evidence demonstrates that chronic inflammation, a non traditional risk factor which is commonly observed in ESRD patients, may be associated with the presence of poor nutritional parameters and progressive atherosclerotic CVD. Based on these observations, the presence in ESRD patients of a syndrome consisting in malnutrition, signs of systemic chronic inflammation and atherosclerosis (MIA syndrome) has recently been suggested. A central role in this syndrome is played by the proinflammatory cytokines generated in response to factors such as chronic renal failure and infectious-inflammatory co-morbid disease. It is now clear that the immune response, both innate and adaptive, is the main cause of inflammation characterising atherosclerosis. As there is as yet no recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various inflammatory treatment strategies on the nutritional and cardiovascular status as well as the outcome in these patients.

[Chorea in hemodialysis: Is chorea just a neurological syndrome or is it related to uremia or dialysis?]. / Corea in emodializzato: sindrome strettamente neurologica o correlata all'uremia e alla dialisi?

Chronic renal failure and haemodialysis patients are prone to develop encephalopathy. The causes of encephalopathy are often unclear. Clinical signs of encephalopathy in the uraemic patient often overlap with several other affections causing neurological disorders. Whenever basal ganglia are anatomically involved, movement disorders arise, including chorea. Some acute and chronic neurological syndromes associated with chronic uraemia have consistently been reported (uraemic encephalopathy, dialysis disequilibrium syndrome, dialysis dementia, nephroangiosclerosis neuropathy and ageing neuropathy). Other clinical conditions in which neurological involvement exists are not so frequent in both haemodialysis patients and in the general population (Wernicke's encefalopathy, Creutzfeldt-Jacob disease). Because of the non specific symptoms and the very heterogeneous aetiology, a careful physical examination should be performed in haemodialysis patients with clinical signs of encephalopathy and the main metabolic alterations should be sought; moreover, central nervous system imaging examination is often appropriate. In case of basal ganglia anatomical involvement, supported by findings of imaging techniques, it is necessary to evaluate individual causes of encephalopathy by means of more accurate tests including analysis of cerebro-spinal fluid, measurement of plasma levels of vitamin B components and laboratory tests searching for more uncommon diseases such as Huntington's chorea and Wilson's disease.

[Evaluation of quality of life by improving the uraemic anaemia status]. / Miglioramento dello stato anemico e valutazione della qualita' di vita del paziente in trattamento dialitico sostitutivo. Applicazione del ciclo dell'"audit" ad una unita' di nefrologia e dialisi.

BACKGROUND: Anaemia is one of the most common signs of chronic uraemia that determines an increase in both morbidity and mortality, as well as a deterioration in the quality of life of affected patients. We evaluated the impact of the application of the European Best Practice Anaemia Guidelines to the quality of life of dialysed patients. PATIENTS AND METHODS: We studied for 12 months (from December 2000 to November 2001) 62 patients in haemodialysis and 22 patients in peritoneal dialysis. For the statistical analysis the following parameters were examined: haemoglobin levels, TSAT, and weekly doses of Epo. To assess the quality of life we asked the patients, at the initial visit and 12 months after treatment, to fill out the "Medical Outcome Study Short Form 36 items Heath Survey" and "Kidney Disease Quality of Life". RESULTS: The significant increase in TSAT levels attained in haemodialysed patients (p = 0.03) induced an increase in haemoglobin levels and consequent reduction in EPO administration (p = 0.04). During the study, a significant improvement in General Health (GH) (p = 0.03) was observed. At the end of the treatment, Physical Functioning (PF) (p = 0.04), Role and Physical Health (RP) (p = 0.02) and Social Functioning (SF) (p = 0.005) showed significant variations. CONCLUSIONS: The application of the European Best Practice Anaemia Guidelines improves the management of anaemia and the Global Health Assessment in uraemic patients. These data demonstrate how inappropriate anaemia management can negatively affect the quality of life of these patients and increase the medical costs.

[DRG's and cost/efficacy indicators in nephrology and dialysis. Results at a hospital division]. / DRG e indicatori di costo/efficacia in nefrologia e dialisi. Risultati in una Divisione ospedaliera.

The Diagnosis Related Groups (DRGs) classification system correlates hospital performance with their relative costs and encourages more efficient productive processes. We report the following parameters: a) the distribution of hospital discharges according to the Major Diagnostic Categories (MDCs) and DRGs; b) the relationship between mean length of stay and threshold values; c) economic analysis of the cost-reimbursement pay-off. The results showed that 71.3% of DRGs belonged to nephro-urological MDC 11 and 28.7% in other internal MDCs (mainly involving cardiac and respiratory system). Of the latter, 67.7% were utilized for dialysis and transplant patients and kidney donors. In MDC 11 the most common DRGs were: the surgical DRG 315, produced by the vascular accesses for hemodialysis and by insertion of Tenckoff catheter for peritoneal dialysis, DRG 316 by cases of acute and chronic renal failure, DRG 332 by biopsy-proven glomerulonephritides. The length of stay was most commonly within range of one-third of threshold value for specific DRG; there was a low percentage of one-day stays and outlier cases. The economic analysis demonstrated that mean daily reimbursement sum was 590,714 ITL. Analysis of the overall costs yielded a mean daily cost of 455,838 ITL. In conclusion, quality indicators show that, appropriately, our specialist activity is largely devoted to the diagnosis and treatment of acute and chronic nephropathies and complications following dialysis and renal transplant.

Complement-dependent NADPH oxidase enzyme activation in renal ischemia/reperfusion injury.

NADPH oxidase plays a central role in mediating oxidative stress during heart, liver, and lung ischemia/reperfusion injury, but limited information is available about NADPH oxidase in renal ischemia/reperfusion injury. Our aim was to investigate the activation of NADPH oxidase in a swine model of renal ischemia/reperfusion damage. We induced renal ischemia/reperfusion in 10 pigs, treating 5 of them with human recombinant C1 inhibitor, and we collected kidney biopsies before ischemia and 15, 30, and 60 min after reperfusion. Ischemia/reperfusion induced a significant increase in NADPH oxidase 4 (NOX-4) expression at the tubular level, an upregulation of NOX-2 expression in infiltrating monocytes and myeloid dendritic cells, and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis along with a marked upregulation of NADPH-dependent superoxide generation. This burden of oxidative stress was associated with an increase in tubular and interstitial expression of the myofibroblast marker α-smooth muscle actin (α-SMA). Interestingly, NOX-4 and NOX-2 expression and the overall NADPH oxidase activity as well as α-SMA expression and 8-oxo-7,8-dihydro-2'-deoxyguanosine synthesis were strongly reduced in C1-inhibitor-treated animals. In vitro, when we incubated tubular cells with the anaphylotoxin C3a, we observed an enhanced NADPH oxidase activity and α-SMA protein expression, which were both abolished by NOX-4 silencing. In conclusion, our findings suggest that NADPH oxidase is activated during ischemia/reperfusion in a complement-dependent manner and may play a potential role in the pathogenesis of progressive renal damage in this setting.

The clinical role of contrast-enhanced ultrasound in the evaluation of renal artery stenosis and diagnostic superiority as compared to traditional echo-color-Doppler flow imaging.

AIM: The purpose of this study was to investigate the feasibility of contrast-enhanced ultrasound (CEUS) in the evaluation of renal artery stenosis as compared with traditional techniques: echo color Doppler (ECD) investigation and selective angiography .CEUS is a technique based on the injection of an intravascular biocompatible tracer, namely an intravenous contrast galactose microparticle suspension containing microbubbles (Levovist), that has a similar rheology to that of red blood cells, allowing quantification of renal tissue perfusion. METHODS: A population of 120 hypertensive patients (82 men, mean age 55) with a systolic abdominal murmur and/or a diagnosis of poly-districtual atherosclerosis was studied by ECD and CEUS (Levovist). Selective angiography was performed in patients with renal artery stenosis demonstrated by one of the two ultrasonographic techniques. RESULTS: Forty of the 120 patients in the study population showed renal artery stenosis at one of the two ultrasound techniques: ECD identified renal artery stenosis in 33 cases and CEUS in 38. Instead, selective angiography had detected renal artery stenosis in 38 patients, the same with renal artery stenosis diagnosed by CEUS. Thus, CEUS sensitivity, specificity and accuracy were similar to those of angiography while six false negatives and two false positives were obtained with ECD. CONCLUSION: Our results suggest that this renal CEUS is a promising, new, non-invasive method for screening patients with suspected renal artery stenosis. This technique appears to be superior to traditional ECD flow imaging for diagnosing renal artery stenosis and so may be an important aid in cardiovascular diagnostics.

Relation of C. pneumoniae antibodies to inflammation and atherosclerosclerosis in dialysis patients.

AIM: the aim of this study was to investigate the association between the presence of antibodies to C. pneumoniae, some markers of inflammation and the presence of preclinical atherosclerotic lesions in hemodyalisis (HD) patients treated with different dialytic membranes. METHODS: C. pneumoniae antibodies were measured by microimmunofluorescence in blood samples of 68 chronic HD patients and in 120 healthy blood donors. Intima-media thickness (IMT) of carotid and of femoral arteries, eco-color doppler of sovraortic trunk and lower limb vessels were evaluated. Plasma levels of C-reactive protein (CRP) and terminal complement (C) complex, C5b-9, were measured. RESULTS: HD patients treated by cellulosic membranes have significantly higher plasma levels of C5b-9 and of CRP compared to those treated by synthetic membranes. A significantly higher prevalence of IgG antibodies to C. pneumoniae and also at higher titre was observed in HD patients in comparison to the controls (66% vs. 28%). The carotid artery mean wall thickness was significantly lower in C. pneumoniae seronegative patients than C. pneumoniae seropositive patients. Similar results were obtained for limb arteries. The use of cellulosic membranes, but not synthetic membranes, was associated with higher carotid IMT and this was independent of the C. pneumoniae serology status. CONCLUSION: in addition to known risk factors, the type of dialytic membrane used may contribute to the progression of atherosclerosis lesions in HD patients. Our data strengthen the evidences that C. pneumoniae infection under high inflammatory status might be a further risk factor for progression of atherosclerosis in HD patients, particularly in those treated with cellulosic membranes.

Bone morphogenetic protein-2 may represent the molecular link between oxidative stress and vascular stiffness in chronic kidney disease.

Oxidative stress and vascular calcifications are emergent risk factors for the accelerated atherosclerosis process featuring chronic kidney disease (CKD). Vascular calcification is an active process similar to bone modelling, where BMP-2 may play a pathogenic role. Aim of our study was to investigate the link between oxidative stress, BMP-2 protein expression and vascular disease in CKD. We enrolled 85 CKD patients (K-DOQI stage II or higher) and 41 healthy individuals. 8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-OHdG) was used as a marker of oxidative stress. Brachial-ankle pulse wave velocity (baPWV) was used as a measure of arterial stiffness. BMP-2 serum levels were significantly higher in CKD patients than in controls (p<0.0001). Serum 8-OHdG levels were significantly higher in CKD patients compared to controls (p<0.05). BMP-2 serum levels were inversely associated with eGFR (r=-0.3; p=0.01) and directly correlated with 8-OHdG serum concentrations (r=-0.3; p=0.03). Arterial stiffness was inversely correlated with eGFR (r=-0.4; p=0.001) and directly correlated with BMP-2 (r=0.3; p=0.03), 8-OHdG (r=0.4, p=0.02) and phosphorus serum levels (r=0.3; p=0.007). In a multiple regression model, phosphorus and BMP-2 were independently correlated with baPWV. In vitro exposure to H(2)O(2) induced a time and dose-dependent increase in BMP-2 expression in an immortalized endothelial cell line. Moreover, H(2)O(2) pre-incubation of cultured vascular smooth muscle cell enhanced the BMP-2-induced up-regulation of ALPL, an osteoblastic phenotype marker. Our data suggest that in CKD BMP-2 may represent the molecular link between oxidative stress and arterial stiffness due to vascular calcification.