Vincenzo Panichi

C-Reactive Protein and Interleukin-6 Levels Are Related to Renal Function in Predialytic Chronic Renal Failure

Background: Several studies have provided convincing evidence that in apparently healthy subjects elevated serum levels of plasma C-reactive protein (CRP) are associated with an increased risk of experiencing myocardial infarction and sudden cardiac death. It has been claimed that, in dialytic patients, the hepatic synthesis of this ‘acute phase response’ plasma protein is primarily induced by the macrophage-derived interleukin 6 (IL-6). Little information is available, however, regarding CRP and IL-6 plasma levels in pre-dialytic renal failure. Methods: Plasma CRP by a modification of the laser nephelometry technique, IL-6 and serum albumin were determined in 103 chronic pre-dialytic patients (mean age 50 ± 6.3 years; creatinine clearance (Cr.cl.) 36.3 ± 23.1 ml/min). Results: CRP was >5 mg/l (normal upper range) in 42% of the global population. CRP and IL-6 were significantly related (r = 0.35, p < 0.0004). CRP and IL-6 were related to renal function (CRP vs. Cr.cl., r = –0.56, p < 0.0001; IL-6 vs. Cr.cl., r = –0.55, p < 0.0001, Spearman correlation coefficient). When patients were divided in tertiles according to renal function, CRP median value resulted 7.9 mg/l (interquartile interval: 5–12) in the first tertile (Cr.cl. <18.5 ml/min), 4.0 mg/l (3–6) in the second tertile (Cr.cl. 18.5–45 ml/min) and 3.2 mg/l (2.7–4.0) in the last tertile (Cr.cl. >45 ml/min) (p < 0.0001). A negative correlation between CRP and S-albumin was also found (r = –0.52, p < 0.0001, Spearman correlation coefficient). Conclusions: IL-6 and CRP were increased and were inversely related to creatinine clearance in our population of 103 chronic predialytic patients. The possibility of a decreased renal clearance of CRP and/or cytokines as a cause of an activated acute-phase response is discussed. A negative correlation between CRP and S-albumin was found confirming the link between chronic inflammation and malnutrition in chronic renal patients.

C REACTIVE PROTEIN IN PATIENTS WITH CHRONIC RENAL DISEASES

Base-line serum levels of plasma C-reactive protein (CRP) are predictive of future myocardial infarction and sudden cardiac death in apparently healthy subjects, suggesting the hypothesis that chronic inflammation might be important in the pathogenesis of atherothrombosis. CRP production is mediated by several inflammatory mediators: interleukin 6 (IL-6) is currently felt to be the major cytokine influencing the acute phase response. CRP and other acute phase proteins are elevated in dialysis patients and cardiovascular diseases represent the single largest cause of mortality in chronic renal failure patients. Little information is available, however regarding CRP and IL-6 plasma levels in pre-dialysis renal failure. Plasma CRP was determined by a modification of the laser nephelometry technique; IL-6 by immunoassay (RD System); and fibrinogen, serum albumin, cholesterol, triglycerides, hematocrit, white blood cell count, erythrocytic sedimentation rate (ESR) and urinary protein levels by standard laboratory techniques. Results were obtained in 102 chronic pre-dialysis patients whose mean age was 53 ± 5.8 years with a mean creatinine clearance (CCr) of 52 ± 37 mL/min). CRP was greater than 5 mg/L in 25% of the global population. CRP and IL-6 were 4.0 ± 4.6 mg/L and 5.8 ± 5.6 pg/mL, respectively and were not significantly correlated (r = 0.11, p = n.s.). CRP and IL-6 were however related with renal function (CRP versus CCr r = −0.40 p < 0.001; IL-6 versus CCr r = −0.45; p < 0.001). When patients were divided in two groups according to renal function, CRP resulted 7.4 ± 6.3 mg/L in the group of patients with a CCr lower than 20 mL/min (n = 32) and 2.76 ± 4.35 in the group of patients with a CCr higher than 20mL/min (n = 70) (p < 0.0001). CRP and IL-6 were positively related with ESR (r = 0.32 and 0.46 respectively). Serum albumin levels were not significantly different in the two groups of patients (3.2 ± 0.4 versus 3.0 ± 0.5 g/dL). CRP and serum albumin were not significantly related (r = 0.17). CRP and IL-6 correlated positively with ESR (r = 0.32 and 0.46 respectively). In pre-dialysis patients we have demonstrated an increase in both CRP and IL-6 that occurs as renal function decreases. These data provided evidence of the activation – even in the predialysis phase of renal failure – of mechanisms known to contribute to the enhanced cardiovascular morbidity and mortality of the uremic syndrome.

Anaemia and resistance to erythropoiesis-stimulating agents as prognostic factors in haemodialysis patients: results from the RISCAVID study

BACKGROUND Resistance to erythropoiesis-stimulating agents (ESAs) is often associated with chronic inflammation. Here, we investigated how anaemia, ESA resistance and the plasma levels of biological markers of inflammation could influence all-cause and cardiovascular disease morbidity and mortality. METHODS Seven hundred and fifty-three haemodialysis (HD) patients (mean age 66 ± 14.2 years, mean dialytic age 70 ± 77 months and diabetes 18.8%) were enrolled and followed-up for 36 months. Demographic, clinical and laboratory data, co-morbidity conditions, administered drugs, all-cause mortality and fatal/non-fatal cardiovascular (CV) events were recorded. We measured ESA resistance index, C-reactive protein (CRP) and interleukin-6 (IL-6). RESULTS Six hundred and fifty-one patients (86.4%) received ESAs. Patients with haemoglobin level <11 g/dL (n = 225) showed increased risk of CV [relative risk (RR) 1.415, 95% confidence interval (CI) 1.046-1.914] and overall mortality (RR 1.897, 95% CI 1.423-2.530) versus patients with haemoglobin levels >11 g/dL. ESA resistance values categorized into quartiles (Quartile I <5.6, Quartile II 5.7-9.6, Quartile III 9.7-15.4 and Quartile IV >15.4) correlated with all-cause mortality and fatal/non-fatal CV events (RR 1.97, 95% CI 1.392-2.786; RR 1.619, 95% CI 1.123-2.332, respectively). Furthermore, albumin was significantly reduced versus reference patients and correlated with all-cause mortality and CV events; CRP levels were higher in hyporesponders (Quartile IV) (P < 0.001) and predicted all-cause mortality and CV events. IL-6 but not CRP was a strong predictor of ESA resistance. CONCLUSIONS ESA responsiveness can be considered a strong prognostic factor in HD patients and seems to be tightly related to protein-energy wasting and inflammation.

An Overview of Haemodialysis and Oxidant Stress

Today’s patient population is increasingly older. Patients with chronic renal failure therefore start extracorporeal substitutive treatment having congestive heart failure, chronic liver disease, diabetes and so forth. In these patients, however, long-term haemodialytic treatment may add further aggravation on their pre-existing pathological conditions. Oxidative stress and alterations in lipid metabolism are caused by haemodialysis mainly due to (1) bioincompatibility type of reactions such as production of reactive oxygen species by inflammatory cells due to complement-mediated or -independent pathways, and (2) the imbalance between oxidants and antioxidants due to the diffusive loss of hydrophilic vitamins such as ascorbic acid. The events related to the oxidant stress may sustain a state of chronic inflammation. Recent advances suggest that atherosclerosis and proliferation of the smooth muscle are initiated and sustained by inflammatory mechanisms. Therefore, attempts to counterbalance the prooxidant effect of haemodialysis and to reduce the chronic inflammatory state will be presented.

Oxidative Stress and Inflammatory Reaction Modulation by White Wine

Abstract: Wine and olive oil, essential components of the Mediterranean diet, are considered important factors for a healthy life style. Tyrosol (T) and caffeic acid (CA) are found in both extra virgin olive oil and in white wine. Three white wines from the northeast Italy and four white wines from Germany were analyzed for their content of T and CA. These compounds were tested for their antioxidant activity and their capacity to modulate three different cytokines: IL‐1β, IL‐6, and TNF‐α, which are currently considered to be the major cytokines influencing the acute phase of the inflammatory response. Furthermore, the antioxidant activity of T and CA was analyzed by monitoring the oxidation of a redox‐sensitive probe by using laser scanning confocal microscopy. T and CA, applied at nanomolar range, were found to significantly reduce the generation of oxidants induced by azobis‐amidinopropanedihydrochloride. Peripheral blood mononuclear cells (PBMC) from healthy volunteers were incubated at 37°C for 12 hours with 100 ng LPS (E. coli and P. maltofilia). Increasing doses of T and CA (150 nM to 300 μM) were added and cell‐associated IL‐1β and TNF‐α were determined by immunoreactive tests after three freeze‐thaw cycles. IL‐6 release was also determined in cell surnatants. LPS‐stimulated PBMC showed a significant increase in cytokine release, while T and CA, used at nanomolar concentrations, were able to modulate their expression. Taken together, these results suggest a remarkable effect of white wine non‐alcoholic compounds on oxidative stress and inflammatory reaction.

Plasma C-reactive protein in hemodialysis patients: A cross-sectional, longitudinal clinical survey

In hemodialysis patients, C-reactive protein (CRP), an acute-phase reactant, is a sensitive and independent marker of malnutrition, anemia, and amyloidosis. The aim of the present studies was to evaluate CRP and interleukin 6 levels in plasma samples from long-term hemodialysis patients on different extracorporeal modalities associated with or without backfiltration. Two hundred and forty-seven patients were recruited in eight hospital-based centers. All patients had been on their dialytic modality for at least 6 months. At enrollment, 46 hemodialysis patients out of 247 (18.6%) had clinical evidence of pathologies known to be associated with high CRP values. The 201 remaining patients were defined as clinically stable and were on conventional hemodialysis (34%), hemodiafiltration with infusion volumes <10 liters/session (10%), hemodiafiltration with infusion volumes <20 liters/session (32%), and double-chamber hemodiafiltration with infusion volumes <10 liters/session (22%). Analysis of CRP values in the clinically stable patients showed that an unexpectedly high proportion (47%) of the patients had CRP values higher than 5 mg/l (taken as the upper limit in normal human subjects). The values of CRP and interleukin 6 were significantly higher in hemodiafiltration with infusion volumes <10 liters/session than in hemodiafiltration with infusion volumes >20 liters/session, in hemodialysis and in double-chamber hemodiafiltration. The same pattern occurred after 6 months of follow-up in 171 out of 201 clinically stable patients. Hemodialytic conditions that expose to the risk of backfiltration such as low exchange volume hemodiafiltration may induce a chronic inflammatory state as reflected by increased plasma values of both CRP and interleukin 6, thus suggesting the need for hemodialytic strategies that reduce (hemodialysis with low-permeability membranes or hemodiafiltration with infusion volumes >20 liters) or eliminate (double-chamber hemodiafiltration) backfiltration of bacteria-derived contaminants.

Resveratrol, a component of wine and grapes, in the prevention of kidney disease

Abstract: Ischemia is an inciting factor in 50% of incidences of acute renal failure, and it increases the risk of organ rejection after renal transplantation. We have previously demonstrated that resveratrol (RSV) reduces ischemia‐reperfusion (I/R) injury of rat kidney both by antioxidant and anti‐inflammatory mechanisms. However, a clear morphological demonstration of this activity has not been made. To answer this question we have performed a new set of experiments following the experimental protocol reported below to investigate the effects of I/R injury and RSV pretreatment on kidney morphology by computerized morphometric analysis. Both renal arteries were clamped for 40 minutes in 40 male Wistar rats (b.w. 220 ± 20 g); 20 rats were pretreated with RSV 1 μM e.v. 40 minutes before clamping. All animals were reperfused for 24 hours and then sacrificed. Histological examination showed tissue conservation in treated rats. I/R‐induced glomerular collapse (as revealed by mean glomerular volume and glomerular shape factor) was significantly reduced by RSV pretreatment. Capillary tuft/Bowmans capsule area ratio was enhanced in the I/R group suggesting tubular hypertension. RSV pre‐treatments significantly reduced this parameter to the control value. The number of platelet clots in the capillary tuft and tubular necrosis were also reduced by RSV versus I/R group. l‐NAME administration worsened both functional and structural damage. Finally, cGMP urinary levels were markedly reduced from 12.1 ± 8.4 nmol/day to 0.10 ± 0.10 nmol/day in the I/R group. RSV provided cGMP (5.01 ± 1.5 nmol/day, P < 0.05). As expected, l‐NAME administration significantly reduced cGMP in urine (0.71 ± 0.6 nmol/day). The present study confirms the protective effect of RSV pretreatment in I/R injury of rat kidney and suggests multiple mechanisms of action.

PLASMA C-REACTIVE PROTEIN IS LINKED TO BACKFILTRATION ASSOCIATED INTERLEUKIN-6 PRODUCTION

Bacterial contamination of dialysate may enhance cytokine production in hemodialysis. The authors tested the hypothesis that C-reactive protein and interleukin-6 (IL-6) may be linked in a large group of patients exposed to backfiltration of dialysate over a long period of observation. Plasmas stored in a recently published multicenter study were reevaluated. Plasma C-reactive protein and IL-6 concentrations in patients with chronic uremia undergoing hemodiafiltration, which is known to be associated with backfiltration (Group II, 12 patients), were compared with those found in patients treated with a modified hemodiafiltration modality without backfiltration (Group I, 16 patients), and in patients shifted from one modality to the other (Group III, 27 patients), and in 10 patients on hemodialysis (Group IV) in a 1 year multicenter study. Plasma C-reactive and IL-6 both increased significantly (p < 0.002), but slowly (after 8 months) in Group II compared with I, and during the 4 month period in hemodiafiltration with backfiltration in Group III. Backfiltration of dialysate with a moderate to low degree of contamination may enhance synthesis of cytokine and C-reactive protein in the long term. Thus, the relevance for dialytic strategies aiming at improving dialysate quality or at reducing backfiltration is highlighted.

C-Reactive Protein as a Marker of Chronic Inflammation in Uremic Patients

Cardiovascular complications caused by an accelerated atherosclerotic disease represent the largest single cause of mortality in chronic renal failure patients. The rapidly developing atherosclerosis of the uremic syndrome appears to be caused by a synergism of different mechanisms, such as malnutrition, oxidative stress and genetic factors. Recent studies provide evidence that chronic inflammation plays an important role in the pathogenesis of cardiovascular diseases. Elevated serum levels of plasma C-reactive protein (CRP) are associated with an increased risk of experiencing myocardial infarction and sudden cardiac death in apparently healthy subjects. Several recently published papers have confirmed this strong association between CRP and the extent and severity of the atherosclerotic processes. In patients affected by predialytic renal failure, increased levels of CRP and interleukin (IL)-6 were recorded in 25% of our population; CRP and IL-6 were inversely related with renal function. These data suggest the activation – even in the predialytic phase of renal failure – of mechanisms known to contribute to the enhanced cardiovascular morbidity and mortality of the uremic syndrome. In recent years we have investigated the hypothesis that the chronic inflammatory state of the uremic patient could at least in part be due to the dialytic technique. We provide evidence suggesting that the increase of CRP in stable dialytic patients may be due to the stimulation of monocyte/macrophage by backfiltration of dialysate contaminants.

Treatment with 1,25-dihydroxyvitamin D3 preserves glomerular slit diaphragm-associated protein expression in experimental glomerulonephritis.

In this study, we investigated the effect of 1,25(OH)2D3 on proteinuria and on the alteration of slit diaphragm-associated proteins induced by anti-Thy 1.1 in Wistar rats. Four groups of animals were studied: group I, anti-Thy 1.1 treated rats; group II, anti-Thy1.1 treated group that at day 2, after the onset of overt proteinuria, started the treatment with 1,25(OH)2D3; group III, normal control rats injected with vehicle alone; group IV, rats that received only 1,25(OH)2D3. At day 2, in group I and II, before the administration of 1,25(OH)2D3, protein excretion was significantly increased when compared to controls. Overt proteinuria was maintained until day 14 in group I whereas in group II protein excretion was significantly reduced from day 3 to day 14. Moreover, treatment with 1,25(OH)2D3 abrogated podocytes injury, detected as desmin expression and loss of nephrin and zonula occludens-1 (ZO-1), two slit diaphragm-associated proteins, and glomerular polyanion staining, that were observed in group I. In conclusion, these results suggest that 1,25(OH)2D3 administrated with a therapeutic regiment may revert proteinuria, counteracting glomerular podocyte injury.