The Telomere/Telomerase System in Chronic Inflammatory Diseases. Cause or Effect?

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

Determination of telomerase activity on molecular level in b-lymphocytes from patients suffering from renal failure and its correlation with immunologic and biochemic factors

Telomeres are specialized nucleoprotein structures located at the extremities of linear chromosomes which become shortened after each round of cell division. After several cell duplications, telomere length becomes critically short causing genetic instability and thus cell cycle arrest. At this point, if telomeres do not become longer the cell will die. Telomeres are elongated only by telomerase, an enzyme that after development is active in just a handful of cell types in a mature organism. Such cells are lymphocytes.The aim of this study was to investigate the activity of telomerase protein in lymphocytes from chronic kidney disease and hemodialysis patients and to try and uncover if there is a relationship between this activity and the concentration of certain inflammation markers in these patients. These markers were TNF-a, CRP, IL-10 and IL-6. In addition the expression of telomerase catalytic subunit gene (hTERT) was measured in both patients groups and in healthy controls while the expression of tumor suppressor genes p53 and RB was also investigated. Enzymatic activity and gene expression were measured immediately after cell isolation and after the completion of 4 distinct cell cultures (with the addition of LPS or CRP or LPS-LXA4 and without the addition of any specific factor) while inflammation markers were calculated in the blood serum of patients and controls.Renal failure is characterized by a gradual decline in GFR and cause a variety of symptoms from almost every system of the particular organism. In recent years chronic inflammation has emerged as a very crucial mortality and morbidity factor in these patients. The results of this study show that a decrease in telomerase activity is observed in renal failure a fact that is associated with high rates of inflammation markers. In the meantime, even when culture conditions are changed lymphocytes from renal patients are less easy to be stimulated in vitro to divide when compared to healthy individuals. If inflammation is the cause for the decline in telomerase activity remains to be investigated.Τα τελομερή αποτελούν ιδιαίτερες νουκλεοπρωτεϊνικές δομές στα άκρα των ευθύγραμμων χρωμοσωμάτων τα οποία μειώνονται σε μήκος μετά από κάθε κυτταρική διαίρεση. Μετά από ορισμένο αριθμό διαιρέσεων, τα τελομερή βρίσκονται πλέον σε κρίσιμα μικρό μήκος και ως αποτέλεσμα προκαλείται γενετική αστάθεια η οποία έχει ως επακόλουθο την παύση του κυτταρικού κύκλου. Στο σημείο αυτό, αν τα τελομερή δεν επιμηκυνθούν, το κύτταρο θα πεθάνει. Τα τελομερή επιμηκύνονται μόνο από την τελομεράση, ένα ένζυμο που μετά την ανάπτυξη βρίσκεται ενεργοποιημένο σε ελάχιστους τύπους κυττάρων ενός ώριμου οργανισμού, όπως για παράδειγμα είναι τα λεμφοκύτταρα.Σκοπός αυτής της εργασίας ήταν να διερευνηθεί η ενεργότητα της τελομεράσης σε λεμφοκύτταρα ασθενών με χρόνια νεφρική ανεπάρκεια, αιμοκαθαρόμενους ή μη καθώς και να βρεθεί, αν υπάρχει, κάποια συσχέτιση μεταξύ αυτής της ενζυμικής δράσης και της συγκέντρωσης στο αίμα συγκεκριμένων παραγόντων φλεγμονής δηλαδή του TNF-a, της CRP, της IL-10 και της IL-6. Ταυτόχρονα στις δύο ομάδες ασθενών (αιμοκαθαρόμενοι και νεφροπαθείς μη αιμοκαθαρόμενοι) αλλά και στους φυσιολογικούς μάρτυρες, μελετήθηκε η έκφραση του γονιδίου της καταλυτικής υπομονάδας της τελομεράσης hTERT, καθώς και των ογκοκατασταλτικών γονιδίων p53 και RB. Η ενζυμική ενεργότητα και η γονιδιακή έκφραση μετρήθηκαν τόσο αμέσως μετά την απομόνωση των λεμφοκυττάρων όσο και μετά από 4 συγκεκριμένες κυτταροκαλλιέργειες (με προσθήκη LPS ή CRP ή LPS-LXA4, και χωρίς την προσθήκη κάποιου παράγοντα) ενώ οι παράγοντες φλεγμονής υπολογίστηκαν στον ορό αίματος ασθενών και μαρτύρων.Η χρόνια νεφρική ανεπάρκεια χαρακτηρίζεται από προοδευτική μείωση του ρυθμού σπειραματικής διήθησης και προκαλεί συμπτώματα από όλα σχεδόν τα συστήματα ενός οργανισμού. Σχετικά πρόσφατα αποκαλύφθηκε πως η χρόνια φλεγμονή αποτελεί έναν σημαντικό παράγοντα νοσηρότητας και θνητότητας στους ασθενείς αυτούς. Τα αποτελέσματα της έρευνας έδειξαν πως στη χρόνια νεφρική ανεπάρκεια προκαλείται μείωση της δραστηριότητας της τελομεράσης, γεγονός που συνδυάζεται με υψηλούς τίτλους παραγόντων φλεγμονής. Ταυτόχρονα παρά τις διάφορες αλλαγές στις συνθήκες καλλιέργειας τα κύτταρα των ασθενών ενεργοποιούνται in vitro δυσκολότερα ώστε να διαιρεθούν συγκριτικά με τους φυσιολογικούς μάρτυρες. Αν η φλεγμονή είναι αυτή που προκαλεί τη μειωμένη ενζυμική δραστικότητα είναι ακόμη προς διερεύνηση

The Telomere/Telomerase System in Chronic Inflammatory Diseases. Cause or Effect?

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

The Telomere/Telomerase System in Chronic Inflammatory Diseases. Cause or Effect?

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

Transcription of the tumor suppressor genes p53 and rb in lymphocytes from patients with chronic kidney disease: Evidence of molecular senescence?

Patients suffering from renal failure exhibit an impaired immune system function. We wanted to investigate the transcription of the tumor suppressor genes p53 and RB to record, if these cells could be stimulated in vitro in 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 A(LXA-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 stimulated in vitro in order to duplicate. © 2012 Vasileios Kordinas et al

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 sgp 130 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. Copyright (C) 2005 S. Karger AG, Basel

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. Methods: Telomerase activity was measured by PCR-ELISA in PBMC isolated from a group of 42 HD patients and 39 subjects with estimated glomerular filtration rate >= 80 mL/min (control group). Serum oxidized low-density lipoprotein (ox-LDL), tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) were also measured in both groups by ELISA. Results: Ox-LDL was negatively correlated to percentage telomerase activity in PBMC (r = -0.506, P = 0.000 in the whole group of 81 HD and normal subjects and r = -0.559, P < 0.001 in HD patients). TNF was also inversely associated with percentage telomerase activity in the whole group studied (r= -0.492, P= 0.000) while IL-10 was not. In stepwise multiple linear regression, taking into consideration the most important characteristics of the HD patients and control group, the only significant predictors for percentage telomerase activity in PBMC were ox-LDL and TNF (beta = -0.421, t= -4.083, P= 0.000 and beta= -0.381, t= -3.691, P= 0.000, respectively) while examining separately HD patients, the predictors for the same parameter were ox-LDL and HD duration (beta = -0.671, t = -4.709, P = 0.000 and beta= -0.349, t = -2.447, P = 0.023, respectively). Conclusion: Ox-LDL serum level is inversely correlated to telomerase activity in PBMC of HD patients. Our study proposes a new consequence of increased oxidative stress in HD patients: the premature cellular senescence potentially related to atherosclerosis through LDL oxidation

Is there a connection between inflammation, telomerase activity and the transcriptional status of telomerase reverse transcriptase in renal failure?

Telomerase is involved in the elongation of telomeres. It remains active in very few types of cell in mature organisms. One such cell type is the lymphocytes. In this study, we investigated the activity and expression of telomerase in lymphocytes from renal failure patients and compared it to that for normal controls. Inflammation status was determined at the same time. The enzyme activity was measured using PCR-ELISA with peripheral blood mononuclear cells (PBMCs) from three groups: 53 healthy individuals, 50 patients with chronic kidney disease (CKD) and 50 dialysis patients. In the same cell populations, the expression of the reverse transcriptase of the human telomerase gene (hTERT) was measured via real-time PCR. The inflammationstatus of these individuals was determined by calculating the interleukin 6 (IL-6), IL-10, C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-a) serum concentrations via ELISA. The lowest levels of telomerase activity were detected in CKD, and this group had the highest IL-6 and CRP values and the lowest hTERT expression. The dialysis group showed significant differences in comparison to the normal subjects and to the CKD patients. Further studies are warranted in order to explore the way inflammation influences telomerase activity and hTERT expression. © University of Wrocław, Poland 2015