Telomeres are specialized nucleoprotein structures located at the end of linear chromosomes and telomerase is the enzyme responsible for telomere elongation. Telomerase activity is a key component of many cancer cells responsible for rapid cell division but it has also been found by many laboratories around the world that telomere/telomerase biology is dysfunctional in many other chronic conditions as well. These conditions are characterized by chronic inflammation, a situation mostly overlooked by physicians regarding patient treatment. Among others, these conditions include diabetes, renal failure, chronic obstructive pulmonary disease, etc. Since researchers have in many cases identified the association between telomerase and inflammation but there are still many missing links regarding this correlation, the latest findings about this phenomenon will be discussed by reviewing the literature. Our focus will be describing telomere/telomerase status in chronic diseases under the prism of inflammation, reporting molecular findings where available and proposing possible future approaches.

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.

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.

Patients suffering from renal failure exhibit an impaired immune system function. We wanted to investigate the transcription of the tumor suppressor genesp53andRBto record, if these cells could be stimulatedin vitroin order to divide, after the addition of antigenic and inflammatory factors. This expression was measured by real-time PCR in peripheral blood mononuclear cells (PBMCs) from three different groups: ten healthy individuals, ten patients with chronic kidney disease (CKD), and ten dialysis patients with end stage renal disease (ESRD). The transcription rate of these genes was also measured after the cultivation of PBMCs under four different conditions: just with the culture medium, with lipopolysaccharide (LPS), with C-reactive protein (CRP), and with lipoxin A₄(LXA₄)-LPS. Our results show that in most cases after the cultivation with additives, the transcription levels were higher in dialysis patients compared to those of the other two groups. Our findings serve as indications of cellular senescence on a molecular level, while it seems that these cells are less easily stimulatedin vitroin order to duplicate.