Lymphocyte telomere dynamics and telomerase activity in inflammatory bowel disease: effect of drugs and smoking

Pulmonary, Hepatic, and Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Telomere Biology Disorders

PURPOSE OF THE REVIEW

This study aimed to summarize evidence and provide consensus-based guidelines for management of transplantation in patients with telomere biology disorders (TBD). Specifically, this review focuses on clinical management of lung, liver, and bone marrow transplantation in TBD patients.

RECENT FINDINGS

TBD patients have specific unique biological vulnerabilities such as T cell immunodeficiency, susceptibility to infections, hypersensitivity to chemotherapy and radiation, and cytopenias. Furthermore, multiple organ involvement at diagnosis makes clinical management especially challenging due to higher degree of organ damage, and stress-induced telomeric crisis. Sequential and combined organ transplants, development of novel radiation and alkylator-free conditioning regimen, and use of novel drugs for graft-versus-host disease prophylaxis are some of the recent updates in the field. Multidisciplinary management is essential to optimize transplant outcomes in patients with TBD. In this review, we provide consensus-based transplant management guidelines for clinical management of transplant in TBD.

A new face of old cells: An overview about the role of senescence and telomeres in inflammatory bowel diseases

Cellular senescence is a pivotal factor contributing to aging and the pathophysiology of age-related diseases. Despite the presence of inflammation and abnormal immune system function in both inflammatory bowel diseases (IBD) and senescence, the relationship between the two remains largely unexplored. Therefore, our study aimed to investigate the intricate connection between cellular senescence, telomeres, and IBD. The review highlights the presence of senescence markers, particularly p16 and p21, in IBD patients, suggesting their potential association with disease progression and mucosal inflammation. We emphasize the critical role of macrophages in eliminating senescent cells and how disturbance in effective clearance may contribute to persistent senescence and inflammation in IBD. Additionally, we shed light on the involvement of telomeres in IBD, as their dysfunction impairs enterocyte function and disrupts colonic barrier integrity, potentially exacerbating the pathogenesis of the disease. Targeting senescence and telomere dysfunctions holds promise for the development of innovative therapeutic approaches to mitigate intestinal inflammation and alleviate symptoms in IBD patients. By unraveling the precise role of senescence in IBD, we can pave the way for the discovery of novel therapeutic interventions that effectively address the underlying mechanisms of intestinal inflammation, offering hope for improved management and treatment of IBD patients.

Immune-mediated inflammatory diseases and leukocyte telomere length: A Mendelian randomization study

Objective: To elucidate the potential causality of leukocyte telomere length (LTL) with immune-mediated inflammatory diseases (IMIDs), we conducted a Mendelian randomization (MR) study. Methods: The genetically predicted causation between LTL and IMIDs was evaluated using a two-sample MR method. We analyzed 16 major IMIDs, which included systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), ulcerative colitis (UC), Crohn's disease (CD), ankylosing spondylitis (AS), sicca syndrome (SS), rheumatoid arthritis (RA), type 1 diabetes (T1D), primary sclerosing cholangitis (PSC), idiopathic pulmonary fibrosis (IPF), atopic dermatitis (AD), sarcoidosis, hypothyroidism, hyperthyroidism, psoriasis, and childhood asthma. The random-effects inverse-variance weighted (IVW) method was performed as the main analytical approach in MR. Various sensitivity analyses, including MR-Egger, MR robust adjusted profile score (MR-RAPS), weighted median, MR pleiotropy residual sum and outlier (MR-PRESSO) methods, weighted mode, radial plot, and radial regression, were used to guarantee the robustness of the results and detect horizontal pleiotropy. Cochran's Q value was calculated to check for heterogeneity, and the MR Steiger approach was used to test the causal direction. Results: The MR results indicated significant inverse associations of LTL with risks of psoriasis (OR: 0.77, 95% CI: 0.66-0.89, and p = 3.66 × 10^-4), SS (OR: 0.75, CI: 0.58-0.98, and p = 0.03), RA (OR: 0.77, 95% CI: 0.68-0.88, and p = 9.85 × 10^-5), hypothyroidism (OR: 0.84, 95% CI: 0.78-0.91, and p = 7,08 × 10^-6), hyperthyroidism (OR: 0.60, 95% CI: 0.44-0.83, and p = 1.90 × 10^-3), sarcoidosis (OR: 0.67, 95% CI: 0.54-0.83, and p = 2.60 × 10^-4), and IPF (OR: 0.41, 95% CI: 0.29-0.58, and p = 4.11 × 10^-7) in the FinnGen study. We observed that longer LTL was associated with an increased risk of AS susceptibility (OR: 1.51, 95% CI: 1.18-1.94, and p = 9.66 × 10^-4). The results of the IVW method showed no causal relationship between TL and SLE (OR: 0.92, 95% CI: 0.62-1.38, and p = 0.69) in the FinnGen study; however, a significantly positive correlation was shown between LTL and SLE in another larger GWAS (OR: 1.87, 95% CI: 1.37-2.54, and p = 8.01 × 10^-5). Conclusion: Our findings reveal that abnormal LTL has the potential to increase the risk of IMIDs. Therefore, it could be treated as a predictor and may provide new potential treatment targets for IMIDs. However, the change of LTL may not be the direct cause of IMIDs. Further studies should aim at the pathogenic mechanism or potential protective effects of LTL in IMIDs.

Telomeres: New players in immune-mediated inflammatory diseases?

Telomeres are repetitive DNA sequences located at the ends of linear chromosomes that preserve the integrity and stability of the genome. Telomere dysfunctions due to short telomeres or altered telomere structures can ultimately lead to replicative cellular senescence and chromosomal instability, both mechanisms being hallmarks of ageing. Chronic inflammation, oxidative stress and finally telomere length (TL) dynamics have been shown to be involved in various age-related non-communicable diseases (NCDs). Immune-mediated inflammatory diseases (IMIDs), including affections such as inflammatory bowel disease, psoriasis, rheumatoid arthritis, spondyloarthritis and uveitis belong to this group of age-related NCDs. Although in recent years, we have witnessed the emergence of studies in the literature linking these IMIDs to TL dynamics, the causality between these diseases and telomere attrition is still unclear and controversial. In this review, we provide an overview of available studies on telomere dynamics and discuss the utility of TL measurements in immune-mediated inflammatory diseases.

Cost-Effective Trap qPCR Approach to Evaluate Telomerase Activity: an Important Tool for Aging, Cancer, and Chronic Disease Research

OBJECTIVES

Telomeres are a terminal "DNA cap" that prevent chromosomal fusion and degradation. However, aging is inherent to life, and so is the loss of terminal sequences. Telomerase is a specialized reverse transcriptase encoded by self-splicing introns that counteract chromosome erosion. Telomerase activity is observed during early embryonic development, but after the blastocyst stage, the expression of telomerase reduces. The consequences of either insufficient or unrestrained telomerase activity underscore the importance of ongoing studies aimed at elucidating the regulation of telomerase activity in humans. In the present study, we aimed to standardize a simplified telomerase repeat-amplification protocol (TRAP) assay to detect telomerase activity in unstimulated and PHA-stimulated mononuclear cells.

METHODS AND RESULTS

Our optimized qPCR-based can efficiently evaluate telomerase activity. Quantification of protein and DNA between unstimulated and PHA-stimulated peripheral blood mononuclear cells revealed cellular activation and cell-cycle entry. The assay also showed that relative telomerase activity is significantly different between these two conditions, supporting the applicability of the assay. Furthermore, our findings corroborated that telomerase activity decreases with age.

CONCLUSIONS

Telomeres and telomerase are implicated in aging and development of chronic diseases and cancer; however, difficulty in accessing commercial kits to investigate these aspects is a critical constraint in health surveillance studies. Our optimized assay was successfully used to differentiate telomerase activity between unstimulated and stimulated cells, clearly showing the reactivation of telomerase upon cell activation. This assay is affordable, reproducible, and can be executed in resource-limited settings.

The impact of tobacco smoking on treatment choice and efficacy in inflammatory bowel disease

Smoking significantly increases the risk of developing and worsens Crohn's disease (CD), yet protects against the development and reduces the severity of ulcerative colitis. It is less clear whether smoking impacts the efficacy of therapeutics in inflammatory bowel disease (IBD). We review the literature regarding the relationship between smoking and the efficacy of medical and surgical therapy in IBD. Smoking is associated with alterations in thiopurine metabolism and may affect time to disease relapse. The outcomes of anti-tumor necrosis factor therapy in active smokers appear neutral with data lacking for newer biologics. Smoking increases the risk of postoperative recurrence in those requiring resection for CD, likely attributable to perturbations of the gut microbiota although further implications of these for disease onset/progression and treatment efficacy remain unclear. Multiple lifestyle and psychosocial confounders are likely under-recognized cofactors in the association between smoking and IBD. Despite the widely promulgated risks associated with cigarette smoking in CD, more incisive data are required to further elucidate the actual relationship between smoking and disease pathways, while accounting for the several negative cofactors prevalent in smokers which cast uncertainty on the magnitude of the direct effect of smoking on disease pathophysiology and the efficacy of therapy.

Aging Kidney and Aging-Related Disease

With the development of society and improvement of health care, the life span is much longer than before, which brings serious aging problems. Among all the aging problems, renal aging grows to be nonnegligible issue. The aging process of kidney is always accompanied with structural and functional changes. Molecular changes, including Klotho and Sirtuins, are the basic causes of phenotypical changes. Cell senescence and cell autophagy play fundamental roles in the process of renal aging. To effectively intervene in the process of renal aging, different methods have been tried separately, which could produce different effects. Effective intervention of renal aging could be meaningful for healthy state of the whole body.

Telomerase activity, telomere length and hTERT DNA methylation in peripheral blood mononuclear cells from monozygotic twins with discordant smoking habits

Increased telomerase expression has been implicated in the pathogenesis of lung cancer and, since the primary cause of lung cancer is smoking, an association between telomerase reactivation and tobacco smoke has been proposed. In this work an investigation has been performed to assess the relationship between tobacco smoke exposure and telomerase activity (TA) in peripheral blood mononuclear cells of healthy smokers. The methylation status of the catalytic subunit of telomerase hTERT was concurrently investigated to assess the possible association between epigenetic modifications of hTERT and TA. Besides, the association between smoke and telomere length (TL) has been evaluated. Healthy monozygotic twins with discordant smoking habits were selected as study population to minimize inter-individual differences because of demographic characteristics and genetic heterogeneity. Statistically significant higher values of TA and TL were observed in smokers compared to nonsmoker co-twins. The multivariate analysis of data showed, besides smoking habits (P = 0.02), an influence of gender (P = 0.006) and BMI (P = 0.001) on TA and a borderline effect of gender (P = 0.05) on TL. DNA methylation analysis, focused on 100 CpG sites mapping in hTERT, highlighted nine CpG sites differentially methylated in smokers. When co-twins were contrasted, selecting as variables the intra-twin difference in TA and hTERT DNA methylation, a statistically significant inverse correlation (P = 0.003) was observed between TA and DNA methylation at the cg05521538 site. In conclusion, these results indicate an association of tobacco smoke with TA and TL and suggest a possible association between smoke-induced epigenetic effects and TA in healthy smokers. Environ. Mol. Mutagen. 58:551-559, 2017. © 2017 Wiley Periodicals, Inc.

Chronic kidney disease and premature ageing

Chronic kidney disease (CKD) shares many phenotypic similarities with other chronic diseases, including heart failure, chronic obstructive pulmonary disease, HIV infection and rheumatoid arthritis. The most apparent similarity is premature ageing, involving accelerated vascular disease and muscle wasting. We propose that in addition to a sedentary lifestyle and psychosocial and socioeconomic determinants, four major disease-induced mechanisms underlie premature ageing in CKD: an increase in allostatic load, activation of the 'stress resistance response', activation of age-promoting mechanisms and impairment of anti-ageing pathways. The most effective current interventions to modulate premature ageing-treatment of the underlying disease, optimal nutrition, correction of the internal environment and exercise training-reduce systemic inflammation and oxidative stress and induce muscle anabolism. Deeper mechanistic insight into the phenomena of premature ageing as well as early diagnosis of CKD might improve the application and efficacy of these interventions and provide novel leads to combat muscle wasting and vascular impairment in chronic diseases.

Effects of smoking on human telomerase reverse transcriptase expression in the skin

BACKGROUND

Telomeres are DNA-protein complexes that cap chromosomal ends, promoting chromosome stability. Telomerase is a ribonucleoprotein complex with a direct telomere protective function. Telomere shortening represents lifetime exposure to oxidative stress and is negatively correlated with age, smoking, and mortality. Smoking increases oxidative DNA modification and thus may influence telomere dynamics and human telomerase reverse transcriptase (hTERT) activity.

OBJECTIVES

This study investigated the effect of smoking on hTERT expression in the skin of smokers and non-smokers.

METHODS

A cross-sectional study in 20 current smokers and 20 non-smokers was conducted. Three-mm punch skin biopsies were obtained. Biopsies were examined in routine hematoxylin and eosin staining and immunohistochemistry to investigate expression of hTERT.

RESULTS

All skin biopsies from smokers and non-smokers showed cytoplasmic staining in epidermal cells. Sections positive for hTERT expression showed nuclear and some nucleolar staining in cells of the basal and suprabasal layers. In the dermis, hTERT expression was present in some skin appendages. The epidermis of smokers showed positive hTERT in 55% and negative hTERT in 45% of biopsies. The epidermis of non-smokers showed positive hTERT in 70% and negative hTERT in 30% of biopsies (P > 0.05). Among smokers, 20% showed positive and 80% showed negative hTERT expression in the dermis. Among non-smokers, 30% showed positive and 70% showed negative hTERT expression in the dermis. A higher mean pack year value was found in subjects with negative rather than positive hTERT expression (P < 0.01). In addition, pack year was inversely correlated with hTERT expression in the epidermis (P < 0.05): as pack year increased, hTERT expression decreased. Mean pack year values were higher in subjects with negative rather than positive hTERT expression in the dermis (P < 0.01).

CONCLUSIONS

This research focused on smoking as a lifestyle factor that may alter telomere length and subsequently telomerase kinetics in the skin. Findings showed a higher percentage of negative hTERT in the epidermis and dermis among smokers compared with non-smokers and a higher percentage of positive hTERT expression among non-smokers (not significant). The results of this work showed a statistically significant higher mean pack year count among cases with negative rather than positive hTERT expression in the epidermis and dermis. Pack year count was inversely correlated to hTERT scoring in the epidermis (percentage of cells stained) and hTERT expression in the dermis. Thus, smoking may affect telomerase activity in the skin, thereby contributing to skin aging.

Altered mRNA expression of telomere binding proteins (TPP1, POT1, RAP1, TRF1 and TRF2) in ulcerative colitis and Crohn's disease

AIMS

To determine mRNA expression of telomeric binding proteins in inflammatory bowel disease (IBD), and to note any effects of pharmacotherapy on telomere binding protein expression.

METHODS

Peripheral blood mononuclear cells (PBMC) obtained from 31 IBD patients and 13 controls were activated with phytohaemagglutinin and purified to yield activated (CD25+) T lymphocytes. TPP1, POT1, RAP1, TRF1 and TRF2 mRNA expression in PBMC and activated T lymphocytes was measured with RT-PCR.

RESULTS

In activated (CD25+) T lymphocytes, mean TRF2 mRNA levels were lower in both UC (6.6 vs 10, p=0.004) and CD subjects (6.9 vs 10; p=0.004). Similarly. in activated (CD25+) T lymphocytes mean RAP1 mRNA expression was significantly lower in UC subjects (4.5 vs 9.8, p=0.029) but not in CD subjects. In resting PBMC, mean TRF1 mRNA levels were lower in both UC (2.6 vs 3.5; p=0.008) and CD subjects (1.0 vs 3.5; p=0.04). No difference in PBMC and activated (CD25+) T lymphocytes mRNA levels of TPP1 and POT1 were noted in either UC or CD subjects. An association with 5-aminosalicylate therapy (R(2)=0.4) was only detected with RAP1 mRNA expression. TRF2 mRNA expression was inversely associated with disease duration only in UC subjects (p=0.05; R(2)=-0.6).

CONCLUSIONS

The downregulation of TRF2 and RAP1 mRNA expression in CD25+ T-lymphocytes in IBD suggests that these telomere binding proteins play a role in telomere regulation and may contribute to the telomeric fusions and chromosomal abnormalities observed in UC. These findings may also indicate a systemic process of telomere uncapping which could represent a biomarker for IBD associated cancer risk.

Mechanisms underlying development of ulcerative colitis-associated colorectal carcinoma

Ulcerative colitis (UC) is a chronic inflammatory disease of the gastrointestinal tract arising from the genetic predisposing factor and the abnormality of the immune system. Long-term course of UC may cause the development of several complications, such as colorectal carcinoma. The mechanisms underlying the development of UC-associated colorectal carcinoma, involving a series of changes from genetic materials to signal transduction, are extremely complicated and differ from those behind the development of sporadic colorectal carcinoma. This article discusses the mechanisms underlying the development of UC-associated colorectal carcinoma.

Correlation of telomere length and telomerase activity with occult ovarian insufficiency

BACKGROUND

Occult ovarian insufficiency is associated with infertility, impaired response to ovarian stimulation, and reduced live birth rates in women treated with assisted reproductive technologies. Although a decline in ovarian follicle number is expected with age, the proximate causes of occult ovarian insufficiency in young women remain poorly understood. Abnormalities in telomere length and telomerase activity in human granulosa cells may serve as molecular markers for this condition.

METHODS

A cross-sectional study was performed. Subjects (37 yr old or less) undergoing in vitro fertilization were classified as cases of occult ovarian insufficiency or controls with mechanical infertility (male or tubal factor). Granulosa cells were acquired at the time of oocyte retrieval to quantify telomere length and telomerase activity.

RESULTS

Fifty-four women were enrolled. Human granulosa cell telomerase activity was demonstrated, and lack of granulosa cell telomerase activity was associated with occult ovarian insufficiency (odds ratio, 11.0; 95% confidence interval, 1.3-495.6; P = 0.02). Telomeres were shorter in women with occult ovarian insufficiency than in controls (relative telomere/single copy gene ratio, 1.88 vs. 3.15; P = 0.039).

CONCLUSIONS

Aberrant telomere homeostasis is associated with occult ovarian insufficiency in young women. This finding is consistent with the presence of telomeric attenuation that has been shown in multiple age-related conditions.

Ulcerative colitis is a disease of accelerated colon aging: evidence from telomere attrition and DNA damage

BACKGROUND & AIMS

Telomere shortening is implicated in cancer and aging and might link these 2 biologic events. We explored this hypothesis in ulcerative colitis (UC), a chronic inflammatory disease that predisposes to colorectal cancer and in which shorter telomeres have been associated with chromosomal instability and tumor progression.

METHODS

Telomere length was measured by quantitative polymerase chain reaction in colonocytes and leukocytes of 2 different sets of UC patients and compared with normal controls across a wide range of ages. For a subset of patients, telomere length was measured in epithelium and stroma of right and left colon biopsy specimens. A third set of biopsy specimens was analyzed for phosphorylation of histone H2AX (gammaH2AX), a DNA damage signal, by immunofluorescence and for telomere length by quantitative fluorescence in situ hybridization. Relationships between telomere length, gammaH2AX intensity, age, disease duration, and age of disease onset were explored.

RESULTS

Colonocyte telomeres shorten with age almost twice as rapidly in UC patients as in normal controls. This extensive shortening occurs within approximately 8 years of disease duration. Leukocyte telomeres are slightly shorter in UC patients than in controls, but telomeres of colon stromal cells are unaffected. gammaH2AX intensity is higher in colonocytes of UC patients than in controls and is not dependent on age or telomere length.

CONCLUSIONS

Colonocytes of UC patients show premature shortening of telomeres, which might explain the increased and earlier risk of cancer in this disease. Shorter leukocyte telomeres and increased gammaH2AX in colonocytes might reflect oxidative damage secondary to inflammation.

Telomere length assessment: biomarker of chronic oxidative stress?

Telomeres are nucleoprotein structures, located at the ends of chromosomes and are subject to shortening at each cycle of cell division. They prevent chromosomal ends from being recognized as double strand breaks and protect them from end to end fusion and degradation. Telomeres consist of stretches of repetitive DNA with a high G-C content and are reported to be highly sensitive to damage induced by oxidative stress. The resulting DNA strand breaks can be formed either directly or as an intermediate step during the repair of oxidative bases. In contrast to the majority of genomic DNA, there is evidence that telomeric DNA is deficient in the repair of single strand breaks. Since chronic oxidative stress plays a major role in the pathophysiology of several chronic inflammatory diseases, it is hypothesized that telomere length is reducing at a faster rate during oxidative stress. Therefore, assessment of telomere length might be a useful biomarker of disease progression. In this review several features of telomere length regulation, their relation with oxidative stress, and the potential application of measurement of telomere length as biomarker of chronic oxidative stress, will be discussed.

Short telomere length and breast cancer risk: a study in sister sets

Telomeres consist of a tandem repeats of the sequence TTAGGG at the ends of chromosomes and play a key role in the maintenance of chromosomal stability. Previous studies indicated that short telomeres are associated with increased risk for human bladder, head and neck, lung, and renal cell cancer. We investigated the association between white blood cell telomere length and breast cancer risk among 268 family sets (287 breast cancer cases and 350 sister controls). Telomere length was assessed by quantitative PCR. The mean telomere length was shorter in cases (mean, 0.70; range, 0.03-1.95) than in unaffected control sisters (mean, 0.74; range, 0.03-2.29), but no significant difference was observed (P = 0.11). When subjects were categorized according to the median telomere length in controls (0.70), affected sisters had shorter telomeres compared with unaffected sisters after adjusting for age at blood donation and smoking status [odds ratio (OR), 1.3; 95% confidence interval (95% CI), 0.9-1.8], but the association was not statistically significant. The association by quartile of telomere length (Q4 shortest versus Q1 longest) also supported an increase in risk from shorter telomere length, although the association was not statistically significant (OR, 1.6; 95% CI, 0.9-2.7). This association was more pronounced among premenopausal women (OR, 2.1; 95% CI, 0.8-5.5) than postmenopausal women (OR, 1.3; 95% CI, 0.5-3.6 for Q4 versus Q1). If these associations are replicated in larger studies, they provide modest epidemiologic evidence that shortened telomere length may be associated with breast cancer risk.

Cancer surveillance in inflammatory bowel disease: new molecular approaches

PURPOSE OF REVIEW

Patients with chronic inflammatory bowel disease, such as ulcerative colitis and Crohn's disease, have an increased risk of colorectal cancer. Life-long colonoscopy surveillance is performed to detect the presence of dysplasia, but this approach is expensive and time-consuming. Thus, there is intensive research to identify molecular factors with prognostic value. This review summarizes recent research, with a special emphasis on the mechanisms underlying these molecular alterations.

RECENT FINDINGS

The role of chromosomal instability in the progression to inflammatory bowel disease-associated colorectal cancer is clear and likely relates to chronic cycles of injury, inflammation, repair and telomere shortening. The role of microsatellite instability has been a subject of discussion, and data suggest that microsatellite instability in inflammatory bowel disease might be different from microsatellite instability in sporadic colorectal cancer. Methylation, as a mechanism of gene silencing, also plays a role in ulcerative colitis tumorigenesis. Chronic inflammation has been linked to p53 activation and oxidative stress, contributing to the extensive genomic DNA damage observed in ulcerative colitis.

SUMMARY

Improved understanding of the molecular biology of cancer progression in inflammatory bowel disease will hopefully lead to the identification of useful prognostic biomarkers. Efforts are needed to prove the clinical utility of the most promising markers now identified.