Chrysoula Nicolaou

Telomerase Activity Is Decreased in Peripheral Blood Mononuclear Cells of Hemodialysis Patients

Background: Telomerase preserves telomere length and structure, preventing cellular senescence, which is associated with alteration of the chromosomal ends. We hypothesized that telomerase activity is altered in peripheral blood mononuclear cells (PBMCs) of hemodialysis (HD) patients. To investigate this hypothesis as well as the relationship between telomerase and inflammation, we measured the activity of this reverse transcriptase as well as the level of several inflammatory markers in PBMCs and serum of an end-stage renal failure (ESRF) population and a non-renal-failure group of subjects. Methods: In PBMCs isolated from 42 HD and 39 non-renal-failure subjects of the same age (51.0 ± 12.4 and 51.4 ± 12.1 years, respectively) telomerase activity was measured using PCR-ELISA; the method was based on the telomeric repeat amplification protocol. Results: Telomerase activity in PBMCs was detected in 18 (42.9%) HD and 28 (71.8%) non-renal-failure subjects (p = 0.013). Among positive subjects, percent telomerase activity in PBMCs was significantly higher in non-renal- failure (117 ± 112 %) than in HD (47.6 ± 57.1 %) subjects (p = 0.008). Detectable telomerase activity was lower in long-term than in short-term HD patients (13.3 ± 8.9 vs. 75.0 ± 64.8%, respectively, p = 0.015). Although higher in HD group, inflammatory indexes (C-reactive protein, interleukin-6, IL-6, soluble IL-6 and soluble gp130) were not correlated to telomerase activity in PBMCs. Conclusion: Telomerase activity in PBMCs is reduced in HD patients. It seems that, at least in this type of cell in this population, defense from senescence, as assessed by telomerase activity, is altered and associated with the chronicity of uremia/HD procedure.

Exploring Inflammation in Hemodialysis Patients: Persistent and Superimposed Inflammation

Background: Inflammation is frequently elevated, and seems to be episodic in hemodialysis (HD) patients. Whether, its episodic character is due to the temporal variability, in periods free of clinical events, of the inflammatory indices or due, to the acute phase response induced by common inflammatory stimuli, has not been investigated yet in a longitudinal study. This study explores inflammation forms, characteristics and causes which are probably related to the high cardiovascular disease (CVD) morbidity in HD patients. Methods: In 37 HD patients, high-sensitivity C-reactive protein (hs-CRP), serum amyloid A (SAA) and interleukin-6 (IL-6) were weekly measured for 16 consecutive weeks. Inflammatory clinical events, in the week before every measurement, were recorded. Repeated measures ANOVA were applied for statistical analysis. Results: Fifty-one of 533 patient-weeks were positive for a clinical event. Mean ± SD (range) hs-CRP was 7.01 ± 16.06 (0.2–169) mg/l for all the weeks of the study, 38.25 ± 39.35 (2.1–169) mg/l for the weeks with clinical events and 3.70 ± 3.86 (0.2–26.1) mg/l for the weeks free of events. Variations for SAA and IL-6 were similar. ‘Clinical events’ strongly influenced acute-phase proteins and IL-6 levels. The effect of the factor ‘time’ (as assessed by inflammatory indices variation in weekly repeated measurements) was significant for all the 3 indices measured, independently of the factor ‘clinical events’. Conclusions: In periods free of clinical events, microinflammation characterizes HD patients and fluctuates in time. Inflammation due to common clinical events is added, periodically, to this microinflammation. The high level persistent microinflammation as well as the superimposed – due to clinical events – inflammation could be related to the CVD in these patients.

Serum oxidized low-density lipoprotein is inversely correlated to telomerase activity in peripheral blood mononuclear cells of haemodialysis patients

Background:  Telomerase preserves telomeres’ function and structure preventing cellular senescence. Its activity is reduced in peripheral blood mononuclear cells (PBMC) of haemodialysis (HD) patients. The purpose of this study is to investigate the potential correlation between increased oxidative stress/inflammation and telomerase activity in PBMC of HD patients.

Treatment with Fluvastatin Rapidly Modulates, via Different Pathways, and in Dependence on the Baseline Level, Inflammation in Hemodialysis Patients

Background: Hemodialysis (HD) patients are frequently in an elevated inflammatory state which is correlated to the atherosclerosis-related and overall morbidity and mortality in this population. Statins, beyond their antilipidemic effects, are also considered to have anti-inflammatory, immunomodulating and antioxidant properties. The individual response of HD patients to a short course of fluvastatin, the mechanisms involved in the immunomodulating and anti-inflammatory effects of this drug and the time interval to the appearance of these effects are investigated in this longitudinal study. Methods: In a group of 51 HD patients, fluvastatin 40 mg/day was administered for 4 weeks. Serial measurements of the lipid profile, C-reactive protein (CRP), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), interleukin-10 (IL-10), and serum oxidized LDL (ox-LDL), were performed before, during, and after the treatment period. Results: Total cholesterol was significantly reduced after 14 days of treatment with fluvastatin (from mean ± SD 216.7 ± 34.3 to 179.2 ± 42.3 mg/dl, p < 0.001). IL-6 and ox-LDL were reduced on day 28 (p < 0.001 and p < 0.01, respectively) and IL-10 was increased on day 14 (p = 0.05); CRP did not change significantly during the treatment period while sIL-6R was increased on day 28 of fluvastatin administration (p < 0.05). In a subgroup of patients with CRP, IL-6, sIL-6R, and ox-LDL baseline serum values ≧ the median and IL-10 ≤ the median, CRP was reduced on day 28 of fluvastatin treatment (p < 0.01), IL-6 and ox-LDL were reduced earlier, on day 14 (p = 0.05 and p < 0.05, respectively) while sIL-6R did not change significantly during the treatment period. Conclusions: Treatment with fluvastatin rapidly modulates inflammation in HD patients. Enhancement of anti-inflammatory mechanisms and attenuation of the inflammatory and oxidative state contribute to this modulation. Patients in an elevated baseline inflammatory state respond more rapidly and effectively to the treatment. This immediate and multi-potent action of the statins could be clinically useful in acute atherosclerosis complications or in the treatment of chronic inflammation in HD patients.

Release of Interleukin-6 and Its Soluble Receptors by Activated Peripheral Blood Monocytes Is Elevated in Hypocholesterolemic Hemodialysis Patients

Background: A reverse association between cholesterol level and cardiovascular disease mortality is observed in hemodialysis (HD) patients; this paradoxical relationship may be explained by the coexistence of inflammation. Interleukin-6 (IL-6) is a central regulator of inflammation; its action is augmented by the soluble IL-6 receptor (sIL-6R) and inhibited by the soluble gp130 (sgp130). In order to investigate the potential association of inflammation with cholesterol levels in the HD population, release of soluble IL-6 components by peripheral blood mononuclear cells (PBMCs) was measured in two groups of HD patients with distinctly different lipid profile and in a control group. Methods: Twenty-two HD patients with low serum cholesterol (range 85–171 mg/dl), 23 HD patients with high cholesterol (189–342 mg/dl) and 21 normolipidemic non-renal failure subjects were enrolled in the study. IL-6, sIL-6R and sgp130 were measured by ELISA in the serum and in the supernatant collected from cell cultures of activated or resting PBMCs isolated from all three groups. Results: Serum IL-6 and sgp130 level was higher while sIL-6R was lower in both groups of HD patients compared to the control group. The ex-vivo release of the IL-6 and sgp130 by unstimulated PBMCs did not differ significantly between the three groups but that of the sIL-6R was higher in non-renal failure than in hypercholesterolemic HD subjects. Production of sIL-6R by stimulated PBMCs was higher in low-cholesterol HD patients (p < 0.001) and the same was valid for the sgp130 release (p = 0.034). Release of IL-6 by activated PBMCs was higher in the low-cholesterol compared to the high-cholesterol HD patients group (p = 0.011 for post hoc test). Major serum lipid fractions were inversely correlated to IL-6 and sIL-6R production from stimulated PBMCs in HD but not in non-renal failure subjects. Finally, release of the sgp130 by PBMCs was significantly reduced in 13 hypertriglyceridemic – and hypercholesterolemic – HD patients. Conclusion: Production of soluble components of a crucial pro-inflammatory and potentially atherogenic cytokine, namely the IL-6, by stimulated PBMCs appears to be inversely correlated with the serum cholesterol levels in HD patients.

Serum and peripheral blood mononuclear cells infectious burden: Correlation to inflammation and atherosclerosis in haemodialysis patients

Background:  Infectious agents may be implicated in the inflammatory atherosclerotic process. Not only specific microorganisms but also the infectious burden, defined as the number of pathogens to which a patient is exposed, has been associated with atherosclerosis. In the present study, the infectious burden, determined directly (by identification of viable pathogens in peripheral blood mononuclear cells (PBMC)) and indirectly (by serum antibodies detection) is correlated to the inflammatory and atherosclerotic status in haemodialysis (HD) patients, a population at high risk for cardiovascular disease.

Correlation Between Flagellin A (flaA) Genotypes and Antimicrobial Susceptibility Patterns of Campylobacter jejuni Strains Isolated from Children with Gastroenteritis in Athens, Greece

AbstractBackground and Objective:Campylobacter jejuni is one of the most common enteric pathogens worldwide. The bacterium is transmitted to humans via contaminated food and water. In the majority of cases the disease is self-limiting, but treatment is indicated in immunocompromised patents, in severe cases with septicemia, and in children. The subtyping of clinical, animal, and food C. jejuni isolates is very important for epidemiological studies. In the present study, 192 Campylobacter jejuni isolates characterized by pulsed-field gel electrophoresis (PFGE) of SmaI digested genomic DNA were further examined with respect to their antimicrobial resistance and their flagellin A (flaA) genotypes in order to disclose any correlation between a certain flaA type and a specific antimicrobial susceptibility pattern. Methods:C. jejuni clinical isolates were collected from infected children up to 14 years of age from five general hospitals in the area of Attica, Greece, during the period 2004-7. C. jejuni strain isolation and identification from stool samples were performed by conventional bacteriological methods. SmaI restriction fragments were prepared as described previously for the PFGE analysis. Antimicrobial susceptibility was tested and interpreted by determination of the minimal inhibitory concentration (MIC) by use of the agar dilution method as described by the Clinical Laboratory Standards Institute. FlaA typing was performed by PCR amplification of the corresponding gene, and the product was digested with DdeI and visualized by agarose gel electrophoresis. Data were analyzed using the software Gene Profiler 1-D Gel Analysis and Data Basing for Windows®. Results: A statistically significant correlation between certain flaA genotypes (flaA 17 Greece [GR], flaA 19 GR and flaA 39 GR) and resistance to some antimicrobial agents (ampicillin, amoxicillin/clavulinic acid [co-amoxiclav], erythromycin, nalidixic acid, and ciprofloxacin) was detected in C. jejuni strains isolated from infected children. Conclusions: Further investigations on a molecular basis are warranted in order to clarify whether certain C. jejuni flaA types are associated with specific antimicrobial resistance attributes.