Peripheral Blood Telomere Length Research Articles

Abstract LB096: Telomere length as a predictor of therapy response and survival in patients diagnosed with ovarian carcinoma

Abstract Impaired telomere length (TL) maintenance in ovarian tissue may play a pivotal role in epithelial ovarian carcinoma (OvC) onset. TL in either target or surrogate tissue (blood) is currently being investigated as a predictor in anti-OvC therapy or as a biomarker of the disease progression, respectively. There is presently an urgent need for an appropriate approach to chemotherapy response prediction. We performed a monochrome multiplex qPCR measurement of TL in peripheral blood and tumor tissues of 209 OvC patients. Methylation status and gene expression of shelterin complex and telomerase catalytic subunit (hTERT) were determined within tumor tissues by High-Throughput DNA methylation profiling and RNA sequencing (RNA-Seq) analysis, respectively. The patients sensitive to cancer treatment (n=46) had shorter telomeres in peripheral blood cells compared to those treatment-resistant (n=93; P=0.037). Cancer tissue TL lower than the median predisposed to better overall survival (P=0.002). Gene expression of TPP1, which recruits telomerase to telomeres, was positively associated with TL in tumor tissue (P=0.026). TL measured in peripheral blood cells could serve as a marker of platinum therapy response in OvC patients. Additionally, TL determined in tumor tissue provides information on OvC patients' overall survival. The study was financed by the project NPO (LX22NPO05102), the Czech Health Research Council (NU21-03-00145), and the Czech Science Foundation (21-27902S). Citation Format: Kristyna Tomasova, Karolina Seborova, Michal Kroupa, Josef Horak, Ludmila Vodickova, Lukas Rob, Martin Hruda, Marcela Mrhalova, Alena Bartakova, Jiri Bouda, Thomas Fleischer, Vessela Kristensen, Pavel Vodicka, Radka Vaclavikova. Telomere length as a predictor of therapy response and survival in patients diagnosed with ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB096.

Telomere length of various blood and bone marrow cells in patients with aplastic anemia

Background. Aplastic anemia proceeds with bone marrow failure and is associated with immunological suppression of normal blood stem cells’ proliferation, which lead to bone marrow aplasia. autoimmune aggression and internal defects of blood stem cell that cause abnormal hematopoiesis are being actively studied. An important role in the pathogenesis of the aplastic anemia is played by instability of telomere length (TL). determination of the initial TL makes it possible to clearly differentiate between the aplastic anemia and dyskeratosis congenita. also, it helps to identify the group of patients with short telomeres for prediction of therapy response. Aim. To investigation the TL of various blood and bone marrow cells in patients with aplastic anemia before treatment. Materials and methods. The group of patients with aplastic anemia was investigated (n = 45). blood donors (n = 32) and bone marrow donors (n = 10) of different ages were included in the reference group. adult patients with dyskeratosis congenita (n = 5) were included in the comparison group. Relative and absolute tl was identified in peripheral blood and bone marrow mononuclear cells, monocytes, lymphocytes by flow-FISH technique (combination of flow cytometry and fluorescence in situ hybridization). Results. Relative and absolute TL was comparable in different blood and bone marrow cells in patients with aplastic anemia before treatment. TL in peripheral blood and bone marrow mononuclear cells wasn’t significantly differed in groups of patients with aplastic anemia and healthy donors. Telomeres in patients with dyskeratosis congenita were identified as “ultrashort” and were significantly shorter than in patients with aplastic anemia. Conclusion. Determination of TL in patients with aplastic anemia is modern examination method, which is a necessary step of differential diagnosis between aplastic anemia and dyskeratosis congenita, which is the disease from group of constitutional bone marrow aplasia. It is preferred to identify the TL in adult patients with aplastic anemia by the flow-FISH. It is necessary to investigate the TL to predict treatment response and to identify risks of developing adverse experiences, which include relapse and clonal evolution.

Germline Loss-of-Function Mutations in MDM4 Cause p53-Dependent Hematopoietic Cell Death in Patients with Variable Bone Marrow Failure Phenotypes

The mouse double minute 4 (MDM4) negatively regulates p53 through the p53/MDM2/MDM4 regulatory network and is commonly overexpressed in several cancers. Here, we describe two unrelated pedigrees with germline MDM4 mutations with clinical features of bone marrow (BM) failure. Patient 1 (P1) presented at the age of 11 months with chronic pure red cell aplasia requiring chronic red blood cell transfusions and BM findings with absent erythroid precursors and dysplastic megakaryocytes. Patient 2 (P2) presented at age of 4 weeks with neutropenia with hypogranulation of neutrophils and a normocellular bone marrow with hypoplastic myelopoiesis and dysplasia of all three lineages. Both patients had normal chromosomal breakage and normal for age telomere length in peripheral blood. Whole genome and panel sequencing identified germline heterozygous variants in MDM4: p.Leu31Thrfs*15 in P1 and p.T454M in P2 as the only relevant candidate variants. Both mutations are absent in >140 thousand individuals in gnomAD database, and the constraint analysis indicates that MDM4 gene is intolerant to missense variation (observed to expected (O/E) ratio of 181/258, Z-score 1.71) and highly intolerant to protein truncating variation (O/E: 0/27 with a pLI score of 1). MDM4 protein consists of four key domains: p53 binding N-terminus, an acidic region, a zinc finger domain, and a C-terminal RING domain, which heterodimerizes with MDM2 to ubiquitinate and promote p53 degradation. MDM4 p.T454M missense mutation found in P2 was previously reported by Toufektchan et al. in 2020 in one patient with BM failure phenotype with short telomeres who carried additional TERT variant. The MDM4 p.T454M mutation was shown to result in lower protein levels (consistent with a loss-of-function effect) and had altered capacity to dimerize with the MDM2 RING domain, causing p53 hyperactivity. MDM4 p.Leu31Thrfs*15 mutation described in P1 is localized in the N-terminal p53 binding domain and results in RNA transcript loss, as confirmed by us in patient cells using RNA sequencing showing a two-fold reduction of the dominant transcript [ENST00000367182.8]. This was corroborated by Western blot demonstrating decreased levels of MDM4 protein. We sought to elucidate the impact of p.Leu31Thrfs*15 and p.T454M mutations on hematopoiesis and regulation of p53 expression. In two human induced pluripotent stem cell (iPSC) lines derived from male and female healthy donors, we knocked-in the MDM4 p.T454M and p.Leu31Thrfs*15 mutations by CRISPR/Cas9 engineering. Of note, MDM4 p.Leu31Thrfs*15 homozygous knock-in line could not be established despite multiple attempts. We discovered statistically significant decreased erythroid and myeloid differentiation capacity from MDM4-mutant iPSCs compared to isogenic control iPSCs (p <0.05). There were statistically significantly more AnnexinV+/DAPI+ mutant iPSC-derived myeloid and erythroid progenitors compared to isogenic control-derived progenitors (p <0.05), pointing to a higher rate of cell death in MDM4-mutant cells. We further demonstrated increased expression of p53 and p21 proteins in MDM4 p.Leu31Thrfs*15 iPSC clones. To better understand the loss-of-function effect of MDM4, we knocked out MDM4 in healthy CD34+ cells using CRISPR/Cas9 editing. Knock out of MDM4 with an efficiency of >80% was achieved in multiple biological replicates, resulting in increased p53 activity and fewer blast-forming erythroid (BFU-E) and myeloid colonies compared to control cells that were Cas9-edited at the AAVS1 safe harbor locus. This impairment was rescued by disruption of TP53 gene. Sequencing of individual BFU-E colonies did not reveal any cells with biallelic loss of MDM4, while similar percentages of unedited colonies and heterozygous disrupted MDM4 colonies were detected. Xenotransplantation studies using immunodeficient NBSGW mice are currently underway to explore the impact of MDM4-edited CD34+ cells in vivo. In summary, we describe two patients with germline loss-of-function MDM4 mutations that cause p53 hyperactivity which causes the unifying feature of hematopoietic defect across a BMF disorder spectrum without telomere shortening. Sharma and Bhoopalan are equal contributors

Urinary cadmium and peripheral blood telomere length predict the risk of renal function impairment: a study of 547 community residents of Shanxi, China.

Few reports have investigated the predictive value of urinary cadmium (UCd) and telomere length on renal function impairment. Therefore, we constructed nomogram models, using a cross-sectional survey to analyze the potential function of UCd and telomere length in renal function impairment risk. We randomly selected two community populations in Shanxi, China, and general information of the subjects was collected through face-to-face questionnaire surveys. Venous blood of subjects was collected to detect absolute telomere length (ATL) by real-time quantitative chain reaction (RT-PCR). Collecting urinary samples detected UCd and urinary N-acetyl-β-d-glucosaminidase (UNAG). Estimated glomerular filtration rate (eGFR) was obtained based on serum creatinine (SCr). Nomogram models on risk prediction analysis of renal function impairment was constructed. After adjusting for other confounding factors, UCd (β = 0.853, 95% confidence interval (CI): 0.739 ~ 0.986) and ATL (β = 1.803, 95%CI: 1.017 ~ 1.154) were independent risk influencing factors for increased UNAG levels, and the risk factors for eGFR reduction were UCd (β = 1.011, 95%CI: 1.187 ~ 1.471), age (β = 1.630, 95%CI: 1.303 ~ 2.038), and sex (β = 0.181, 95%CI: 0.105 ~ 0.310). Using UCd, ATL, sex, and age to construct the nomogram, and the C-statistics 0.584 (95%CI: 0.536 ~ 0.632) and 0.816 (95%CI: 0.781 ~ 0.851) were obtained by internal verification of the calibration curve, C-statistics revealed nomogram model validation was good and using decision curve analysis (DCA) confirmed a good predictive value of the nomogram models. In a nomogram model, ATL, UCd, sex, and age were detected as independent risk factors for renal function impairment, with UCd being the strongest predictor.

Hypoplastic Myelodysplastic Syndrome: Clinical, Histopathological and Molecular Characterization

Introduction and AimsHypoplastic Myelodysplasic Syndrome (h-MDS) has distinct features compared to normo- or hypercellular MDS, with a higher response rate to immunosuppressive therapy and more favorable prognosis. However, to date, reproducible diagnostic criteria for h-MDS have not been clearly defined, making differential diagnosis from other bone marrow failure (BMF) syndromes challenging. Based on a large and well-annotated consecutive cohort of patients with BM hypocellularity from two tertiary centres, we aimed to delineate the clinical, histopathological and molecular features of h-MDS.MethodsOf 1262 consecutive adult patients analyzed at King's College Hospital, London, UK and IRCCS Policlinico San Matteo & University of Pavia, Italy: 533 patients had a hypocellular BM, including 205 MDS patients with BM cellularity ≤25%, 77 MDS with reduced age-adjusted BM cellularity, 139 with Aplastic Anemia (AA), 97 with a diagnosis of Idiopathic Cytopenia of Undetermined Significance (ICUS) and 15 with congenital BMF (c-BMF) and 729 with normo- or hypercellular MDS (n-MDS).ResultsComparison of clinical features and outcome of patients with h-MDS as defined by a BM cellularity ≤25% (n=205) and those with a reduced age-adjusted cellularity (n=77) did not detect any significant differences. Therefore, a reduced age-adjusted BM cellularity was adopted as a criterion to define h-MDS (n=282). Compared with patients with n-MDS, those with h-MDS were significantly younger, displayed higher levels of hemoglobin (p=.01), lower neutrophil and platelet counts and lower percentage of BM blasts, ring sideroblasts (RS) and CD34+cells as determined by immunohistochemistry (all p<.001). No significant difference was observed in the distribution of chromosomal abnormalities. A significantly higher prevalence of PNH clones was observed in h-MDS (24% vs 2%, p<.001). Those patients with h-MDS showed a significantly lower risk of leukemic evolution compared with n-MDS (4-year cumulative incidence 14% vs 26%, p=.003). Comparing h-MDS with AA, h-MDS showed a significantly higher percentage of RS (p=.004), BM blasts, dysmegakaryopoiesis and dysgranulopoiesis (p<.001), BM fibrosis (p=.002), clusters of CD34+ cells and chromosomal abnormalities (p<.001). H-MDS patients showed a significantly higher risk of leukemic evolution compared with AA (4-year cumulative incidence 14% vs 0%, p<.001).Targeted sequencing of 24 commonly mutated myeloid genes was performed on 358 patients (73 h-MDS, 45 AA and 240 n-MDS). Twenty-five patients with h-MDS (34%) showed one or more somatic mutation (median 1; range 1-4). Comparing h-MDS to n-MDS revealed a significantly lower number of mutations per subject and variant allele frequency (VAF) (p<.001). Moreover, a significantly lower number of mutations per patient and VAF were observed in AA compared to h-MDS (p=.031 and p=.003, respectively). Thirty-seven patients with a hypocellular BM had a peripheral blood telomere length (TL) ≤1st percentile and/or a germline mutation consistent with a diagnosis of c-BMF, leading to an estimated prevalence of unidentified c-BMF of 13% in cases without robust morphological evidence of MDS.Based on these findings, we defined a diagnostic score (h-score), including variables with the highest specificity for MDS: dysmegakaryopoiesis, dysgranulopoiesis, BM fibrosis, clusters of CD34+ cells, RS 2-14%, BM blasts 2-4% (score 1); RS≥15% and BM blasts ≥5% (score 2). By applying ROC analysis, a cut off value of 2 was associated with the highest specificity for MDS (0.98). Notably, 71% of patients with a hypoplastic BM and low h-score (0-1) had no evidence of clonal disease by cytogenetic or mutation analyses or had a mutation pattern consistent with age-related clonal hematopoiesis. These patients showed a significantly better OS and lower risk of leukemic evolution (P<.001).ConclusionsIntegration of cyto-histological and genetic features in patients with a hypocellular BM identifies two distinct groups, one with clinical and genetic features highly consistent with a clonal disease with high risk of leukemic evolution, and one with features more consistent with a non-malignant bone marrow failure. Furthermore, we identified relevant enrichment of patients with previously undiagnosed c-BMF. DisclosuresKulasekararaj:Akari Therapeutics Plc: Consultancy, Honoraria; Alexion Pharmaceuticals: Consultancy, Honoraria; Ra Pharmaceuticals: Consultancy, Honoraria; Achillion pharmaceuticals: Consultancy, Honoraria.

Inverse changes in telomere length between the blood and brain in depressive-like mice

BackgroundTelomeres are nucleoprotein complexes located at the end of chromosomes. Previous studies have confirmed that telomere length is reduced in the peripheral blood of depression patients. However, studies regarding whether telomere length is altered in brain regions associated with depression are limited. It remains unclear whether the peripheral blood telomere length indicates telomere variation in the brain. MethodsUsing quantitative PCR, we measured telomere length in five brain regions (prefrontal cortex, amygdala, nucleus accumbens, paraventricular nucleus, and hippocampus) from depressive-like mice and in peripheral blood from depressive-like mice and major depressive disorder (MDD) patients. We also examined the expression of telomerase- and alternative lengthening of telomere (ALT)-related genes in the prefrontal cortex and amygdala of depressive-like mice. ResultsTelomeres were shortened in the peripheral blood of depressive-like mice and MDD patients, but were elongated in the prefrontal cortex and amygdala compared with healthy controls. We also observed that the expression of ALT-related genes increased in the prefrontal cortex and amygdala. LimitationsThe amount of human sample was limited. The mechanism of telomere lengthening in the brain of depressive-like mice was not well explained. Mice and humans have inherently different telomere and telomere maintenance systems. ConclusionThese findings illustrate that the telomere length in the peripheral blood may not indicate the dynamics of telomere length in the brain. They offer a new perspective on variable telomere length in different brain regions affected in depression and provide a new basis for understanding the relationship between variable telomere length and MDD.

Predictive and prognostic significance of telomerase levels/telomere length in tissues and peripheral blood in head and neck squamous cell carcinoma

A growing body of evidence indicates that the expression of TERT, the catalytic subunit of telomerase, is a biological marker of progression in several cancers. We investigated the predictive and prognostic role of TERT levels and telomere length in tissues and peripheral blood in patients with head and neck squamous cell carcinoma (HNSCC). High TERT levels in cancer tissues were independently associated with worse response to therapy (odds ratio [OR]:6.26), regional failure (hazard ratio [HR]:5.75), progression (HR:2.12), and death (HR:3.53). Longer telomeres in the mucosa surrounding the tumor (SM) were independently associated with a lower risk of mucosal failure (HR:0.39). While telomere length in peripheral blood mononuclear cells (PBMC) significantly decreased with age, no correlation was found between age and telomere length in SM. No associations were found between TERT levels in plasma and telomere length in PBMC and the prognostic variables. High levels of TERT transcripts in cancer cells represent a reliable prognostic marker for identifying HNSCC patients with risk of progression. The altered relationship of telomere length to age in SM compared with PBMC suggests that in a subset of cases the phenotypically normal SM constitutes an acquired telomere-shortened epithelial field prone to genetic instability.

Rare Protein-Altering Telomere-related Gene Variants in Patients with Chronic Hypersensitivity Pneumonitis.

Rationale: Rare genetic variants in telomere-related genes have been identified in familial, idiopathic, and rheumatoid arthritis-associated pulmonary fibrosis. Short peripheral blood leukocyte (PBL) telomere length predicts poor outcomes in chronic hypersensitivity pneumonitis (CHP).Objectives: Determine the prevalence and clinical relevance of rare protein-altering variants in telomere-related genes in patients with CHP.Methods: Next-generation sequences from two CHP cohorts were analyzed to identify variants in TERT (telomerase reverse transcriptase), TERC (telomerase RNA component), DKC1 (dyskerin pseudouridine synthase 1), RTEL1 (regulator of telomere elongation helicase 1), PARN (poly[A]-specific RNase), and TINF2 (TERF1-interacting nuclear factor 2). To qualify, variants were required to have a minor allele frequency less than 0.005 and be predicted to be damaging to protein function. Variant status (binary variable) was used in statistical association tests, including Cox proportional hazard models for transplant-free survival. PBL telomere length was measured using quantitative PCR.Measurements and Main Results: Qualifying variants were identified in 16 of 144 patients (11.1%; 95% confidence interval [CI], 6.5-17.4) in the discovery cohort and 17 of 209 patients (8.1%; 95% CI, 4.8-12.7) in the replication cohort. Age- and ancestry-adjusted PBL telomere length was significantly shorter in the presence of a variant in both cohorts (discovery: -561 bp; 95% CI, -933 to -190; P = 0.003; replication: -612 bp; 95% CI, -870 to -354; P = 5.30 × 10-6). Variant status was significantly associated with transplant-free survival in both cohorts (discovery: age-, sex-, and ancestry-adjusted hazard ratio, 3.73; 95% CI, 1.92-7.28; P = 0.0001; replication: hazard ratio, 2.72; 95% CI, 1.26-5.88; P = 0.011).Conclusions: A substantial proportion of patients diagnosed with CHP have rare, protein-altering variants in telomere-related genes, which are associated with short peripheral blood telomere length and significantly reduced transplant-free survival.

The aging lung: tissue telomere shortening in health and disease

BackgroundTelomere shortening has been associated with several lung diseases. However, telomere length is generally measured in peripheral blood leucocytes rather than in lung tissue, where disease occurs. Consequently, telomere dynamics have not been established for the normal human lung nor for diseased lung tissue. We hypothesized an age- and disease-dependent shortening of lung tissue telomeres.MethodsAt time of (re-)transplantation or autopsy, 70 explant lungs were collected: from unused donors (normal, n = 13) and patients with cystic fibrosis (CF, n = 12), chronic obstructive pulmonary disease (COPD, n = 11), chronic hypersensitivity pneumonitis (cHP, n = 9), bronchiolitis obliterans syndrome (BOS) after prior transplantation (n = 11) and restrictive allograft syndrome (RAS) after prior transplantation (n = 14). Lungs were inflated, frozen and then scanned using CT. Four tissue cores from distinct lung regions were sampled for analysis. Disease severity was evaluated using CT and micro CT imaging. DNA was extracted from the samples and average relative telomere length (RTL) was determined using real-time qPCR.ResultsThe normal lungs showed a decrease in RTL with age (p < 0.0001). Of the diseased lungs, only BOS and RAS showed significant RTL decrease with increasing lung age (p = 0.0220 and p = 0.0272 respectively). Furthermore, we found that RTL showed considerable variability between samples within both normal and diseased lungs. cHP, BOS and RAS lungs had significant shorter RTL in comparison with normal lungs, after adjustment for lung age, sex and BMI (p < 0.0001, p = 0.0051 and p = 0.0301 respectively). When investigating the relation between RTL and regional disease severity in CF, cHP and RAS, no association was found.ConclusionThese results show a progressive decline in telomere length with age in normal, BOS and RAS lungs. cHP, BOS and RAS lungs demonstrated shorter RTL compared to normal lungs. Lung tissue RTL does not associate with regional disease severity within the lung. Therefore, tissue RTL does not seem to fully reflect peripheral blood telomere length.

BPA exposure is associated with non-monotonic alteration in ESR1 promoter methylation in peripheral blood of men and shorter relative telomere length in peripheral blood of women.

The aim of this study was to evaluate the potential association of urinary Bisphenol A (BPA) levels with estrogen receptor alpha (ESR1) promoter % methylation and relative telomere length in a sample of 482 participants. Urinary BPA concentration was measured using organic phase extraction followed by high performance liquid chromatography mass spectroscopy. Peripheral blood ESR1 promoter % methylation and relative telomere length were measured using direct bisulfite sequencing and real-time polymerase chain reaction, respectively. The mean ± SD urinary BPA concentration adjusted for urinary creatinine was 2.90 ± 4.81 (μg/g creatinine) with a median of 1.86 μg/g creatinine (min-max: <LOD -69.85). There was a potentially non-monotonic relationship between adjusted urinary BPA concentrations and ESR1 promoter % methylation in men. As a matter of fact, for the lowest tertile of ESR1 promoter % methylation, the OR and 95% CI of the middle and highest tertiles of urinary adjusted BPA were 2.54 (1.01-6.39) and 1.64 (0.55-4.86) when compared to the lowest BPA tertile, respectively. After adjustment for potential confounders, similar results remained in men and appeared in the whole cohort. As for relative telomere length, there was a significant trend whereby higher adjusted urinary BPA concentrations were significantly associated with shorter relative telomere length in females. For instance, for the shortest relative telomere length tertile, the OR and 95% CI of the middle and highest tertiles of urinary adjusted BPA were 2.91 (1.38-6.16) and 3.19 (1.57-6.49) when compared to the lowest BPA tertile, respectively. This trend remained significant after adjustment for potential confounders.

Telomerase reverse transcriptase germline mutations and hepatocellular carcinoma in patients with nonalcoholic fatty liver disease.

In an increasing proportion of cases, hepatocellular carcinoma (HCC) develops in patients with nonalcoholic fatty liver disease (NAFLD). Mutations in telomerase reverse transcriptase (hTERT) are associated with familial liver diseases. The aim of this study was to examine telomere length and germline hTERT mutations as associated with NAFLD‐HCC. In 40 patients with NAFLD‐HCC, 45 with NAFLD‐cirrhosis and 64 healthy controls, peripheral blood telomere length was evaluated by qRT‐PCR and hTERT coding regions and intron–exon boundaries sequenced. We further analyzed 78 patients affected by primary liver cancer (NAFLD‐PLC, 76 with HCC). Enrichment of rare coding mutations (allelic frequency <0.001) was evaluated by Burden test. Functional consequences were estimated in silico and by over‐expressing protein variants in HEK‐293 cells. We found that telomere length was reduced in individuals with NAFLD‐HCC versus those with cirrhosis (P = 0.048) and healthy controls (P = 0.0006), independently of age and sex. We detected an enrichment of hTERT mutations in NAFLD‐HCC, that was confirmed when we further considered a larger cohort of NAFLD‐PLC, and was more marked in female patients (P = 0.03). No mutations were found in cirrhosis and local controls, and only one in 503 healthy Europeans from the 1000 Genomes Project (allelic frequency = 0.025 vs. <0.001; P = 0.0005). Mutations with predicted functional impact, including the frameshift Glu113Argfs*79 and missense Glu668Asp, cosegregated with liver disease in two families. Three patients carried missense mutations (Ala67Val in homozygosity, Pro193Leu and His296Pro in heterozygosity) in the N‐terminal template‐binding domain (P = 0.037 for specific enrichment). Besides Glu668Asp, the Ala67Val variant resulted in reduced intracellular protein levels. In conclusion, we detected an association between shorter telomeres in peripheral blood and rare germline hTERT mutations and NAFLD‐HCC.

Exposure to Inorganic Arsenic Is Associated with Increased Mitochondrial DNA Copy Number and Longer Telomere Length in Peripheral Blood.

Background: Exposure to inorganic arsenic (iAs) through drinking water causes cancer. Alterations in mitochondrial DNA copy number (mtDNAcn) and telomere length in blood have been associated with cancer risk. We elucidated if arsenic exposure alters mtDNAcn and telomere length in individuals with different arsenic metabolizing capacity.Methods: We studied two groups in the Salta province, Argentina, one in the Puna area of the Andes (N = 264, 89% females) and one in Chaco (N = 169, 75% females). We assessed arsenic exposure as the sum of arsenic metabolites [iAs, methylarsonic acid (MMA), dimethylarsinic acid (DMA)] in urine (U-As) using high-performance liquid chromatography coupled with hydride generation and inductively coupled plasma mass spectrometry. Efficiency of arsenic metabolism was expressed as percentage of urinary metabolites. MtDNAcn and telomere length were determined in blood by real-time PCR.Results: Median U-As was 196 (5–95 percentile: 21–537) μg/L in Andes and 80 (5–95 percentile: 15–1637) μg/L in Chaco. The latter study group had less-efficient metabolism, with higher %iAs and %MMA in urine compared with the Andean group. U-As was significantly associated with increased mtDNAcn (log2 transformed to improve linearity) in Chaco (β = 0.027 per 100 μg/L, p = 0.0085; adjusted for age and sex), but not in Andes (β = 0.025, p = 0.24). U-As was also associated with longer telomere length in Chaco (β = 0.016, p = 0.0066) and Andes (β = 0.0075, p = 0.029). In both populations, individuals with above median %iAs showed significantly higher mtDNAcn and telomere length compared with individuals with below median %iAs.Conclusions: Arsenic was associated with increased mtDNAcn and telomere length, particularly in individuals with less-efficient arsenic metabolism, a group who may have increased risk for arsenic-related cancer.

Telomerase gene therapy rescues telomere length, bone marrow aplasia, and survival in mice with aplastic anemia

AbstractAplastic anemia is a fatal bone marrow disorder characterized by peripheral pancytopenia and marrow hypoplasia. The disease can be hereditary or acquired and develops at any stage of life. A subgroup of the inherited form is caused by replicative impairment of hematopoietic stem and progenitor cells due to very short telomeres as a result of mutations in telomerase and other telomere components. Abnormal telomere shortening is also described in cases of acquired aplastic anemia, most likely secondary to increased turnover of bone marrow stem and progenitor cells. Here, we test the therapeutic efficacy of telomerase activation by using adeno-associated virus (AAV)9 gene therapy vectors carrying the telomerase Tert gene in 2 independent mouse models of aplastic anemia due to short telomeres (Trf1- and Tert-deficient mice). We find that a high dose of AAV9-Tert targets the bone marrow compartment, including hematopoietic stem cells. AAV9-Tert treatment after telomere attrition in bone marrow cells rescues aplastic anemia and mouse survival compared with mice treated with the empty vector. Improved survival is associated with a significant increase in telomere length in peripheral blood and bone marrow cells, as well as improved blood counts. These findings indicate that telomerase gene therapy represents a novel therapeutic strategy to treat aplastic anemia provoked or associated with short telomeres.

Year in review 2015: Interstitial lung disease, pulmonary vascular disease, pulmonary function, sleep and ventilation, cystic fibrosis and paediatric lung disease.

Keywords: interstitial lung disease; lung function; paediatric lung disease; pulmonary vascular disease; sleep

Oxidative stress, telomere shortening, and DNA methylation in relation to low-to-moderate occupational exposure to welding fumes.

Evidence suggests that exposure to welding fumes is a risk factor for lung cancer. We examined relationships between low‐to‐moderate occupational exposure to particles from welding fumes and cancer‐related biomarkers for oxidative stress, changes in telomere length, and alterations in DNA methylation. We enrolled 101 welders and 127 controls (all currently nonsmoking men) from southern Sweden. We performed personal sampling of respirable dust and measured 8‐oxodG concentrations in urine using a simplified liquid chromatography tandem mass spectrometry method. Telomere length in peripheral blood was measured by quantitative polymerase chain reaction. Methylation status of 10 tumor suppressor genes was determined by methylation‐sensitive high‐resolution melting analysis. All analyses were adjusted for age, body mass index, previous smoking, passive smoking, current residence, and wood burning stove/boiler at home. Welders were exposed to respirable dust at 1.2 mg/m3 (standard deviation, 3.3 mg/m3; range, 0.1–19.3), whereas control exposures did not exceed 0.1 mg/m3 (P < 0.001). Welders and controls did not differ in 8‐oxodG levels (β = 1.2, P = 0.17) or relative telomere length (β = −0.053, P = 0.083) in adjusted models. Welders showed higher probability of adenomatous polyposis coli (APC) methylation in the unadjusted model (odds ratio = 14, P = 0.014), but this was not significant in the fully adjusted model (P = 0.052). Every working year as a welder was associated with 0.0066 units shorter telomeres (95% confidence interval −0.013 to −0.00053, P = 0.033). Although there were no clear associations between concentrations of respirable dust and the biomarkers, there were modest signs of associations between oxidative stress, telomere alterations, DNA methylation, and occupational exposure to low‐to‐moderate levels of particles. Environ. Mol. Mutagen. 56:684–693, 2015. © 2015 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc.

Telomere length in children environmentally exposed to low-to-moderate levels of lead

Shorter relative telomere length in peripheral blood is a risk marker for some types of cancers and cardiovascular diseases. Several environmental hazards appear to shorten telomeres, and this shortening may predispose individuals to disease. The aim of the present cross-sectional study was to assess the effect of environmental exposure to lead on relative telomere length (rTL) in children. A cohort of 99 8-year-old children was enrolled from 2007–2010. Blood lead concentrations (B-Pb) were measured by graphite furnace atomic absorption spectrometry, and blood rTL was measured by quantitative PCR.The geometric mean of B-Pb was 3.28μg/dl (range: 0.90–14.2), and the geometric mean of rTL was 1.08 (range: 0.49–2.09). B-Pb was significantly inversely associated with rTL in the children (rS=−0.25, p=0.013; in further analyses both log-transformed-univariate regression analysis β=−0.13, p=0.026, and R2adj 4%; and β=−0.12, p=0.056 when adjusting for mothers' smoking during pregnancy, Apgar score, mother's and father's ages at delivery, sex and mother's education, R2adj 12%, p=0.011). The effect of lead remained significant in children without prenatal tobacco exposure (N=87, rS=−0.24, p=0.024; in further analyses, β=−0.13, p=0.029, and R2adj 4%). rTL was not affected by sex, the concentrations of other elements in the blood (i.e., cadmium and selenium concentrations), or oxidative injury parameters (total antioxidant status, 8-hydroxydeoxyguanosine and thiobarbituric acid-reactive substances).Lead exposure in childhood appears to be associated with shorter telomeres, which might contribute to diseases, such as cardiovascular disease. The inverse association between blood lead level and the telomeres in children emphasizes the importance of further reducing lead levels in the environment.

Telomere Length and Recurrence Risk after Curative Resection in Patients with Early-Stage Non–Small-Cell Lung Cancer: A Prospective Cohort Study

We hypothesized that telomere length in peripheral blood would have significant predictive value for risk of recurrence after curative resection in non-small-cell lung cancer (NSCLC). This prospective study included 473 patients with histologically confirmed early stage NSCLC who underwent curative therapy at MD Anderson Cancer Center between 1995 and 2008. Relative telomere length (RTL) of peripheral leukocytes was measured by real-time polymerase chain reaction. The risk of recurrence was estimated as hazard ratios (HRs) and 95% confidence intervals (CIs) using a multivariable Cox proportional hazard regression model. Median duration of follow-up was 61 months, and 151 patients (32%) had developed recurrence at time of analysis. Patients who developed recurrence had significantly longer mean RTL compared with those without recurrence (1.13 versus 1.07, p = 0.046). A subgroup analysis indicates that women had longer RTL compared with men (1.12 versus 1.06, p = 0.025), and the patients with adenocarcinoma demonstrated longer RTL compared with those with other histologic types (1.11 versus 1.05, p = 0.042). To determine whether longer RTL in women and adenocarcinoma subgroup would predict risk of recurrence, multivariate Cox analysis adjusting for age, sex, stage, pack year and treatment regimens was performed. Longer telomeres were significantly associated with higher risk of developing recurrence in women (hazard ratio [HR], 2.25; 95% confidence interval [CI], 1.02-4.96, p = 0.044) and adenocarcinoma subgroups (HR, 2.19; 95% CI, 1.05-4.55, p = 0.036). The increased risk of recurrence due to long RTL was more apparent in women with adenocarcinoma (HR, 2.67; 95% CI, 1.19-6.03, p = 0.018). This is the first prospective study to suggest that long RTL is associated with recurrence in early stage NSCLC after curative resection. Women and adenocarcinoma seem to be special subgroups in which telomere biology may play an important role.

Short and long telomeres increase risk of amnestic mild cognitive impairment

Peripheral blood telomere length has been associated with age-related conditions including Alzheimer's disease (AD). This suggests that telomere length may identify subjects at increased risk of AD. Thus, we investigated the associations of peripheral blood telomere length with amnestic mild cognitive impairment (aMCI), a putative precursor of AD, among Mayo Clinic Study of Aging participants who were prospectively followed for incident aMCI. We matched 137 incident aMCI cases (mean age 81.1 years, [range 70.9–90.8]; 49.6% men) by age and sex to 137 cognitively normal controls. We measured telomere length (T/S ratio) at baseline using quantitative PCR. Compared to the middle T/S quintile (Q3), the risk of aMCI was elevated for subjects with the shortest (Q1: HR, 2.85, 95% Confidence interval [CI] 0.98, 8.25; p=0.05) and the longest telomere lengths (Q5: HR, 5.58, 95%CI, 2.21, 14.11; p=0.0003). In this elderly cohort, short and long telomeres were associated with increased risk of aMCI. Our findings suggest that both long and short telomere lengths may play a role in the pathogenesis of aMCI, and may be markers of increased risk of aMCI.

Effect of leukocyte telomere length on total and regional brain volumes in a large population-based cohort.

Telomere length has been associated with dementia and psychological stress, but its relationship with human brain size is unknown. To determine if peripheral blood telomere length is associated with brain volume. Peripheral blood leukocyte telomere length and brain volumes were measured for 1960 individuals in the Dallas Heart Study, a population-based, probability sample of Dallas County, Texas, residents, with a median (25th-75th percentile) age of 50 (42-58) years. Global and 48 regional brain volumes were assessed from the automated analysis of magnetic resonance imaging. Telomere length and global and regional brain volumes. Leukocyte telomere length was associated with total cerebral volume (β [SE], 0.06 [0.01], P <.001) including white and cortical gray matter volume (β [SE], 0.04 [0.01], P = .002; β [SE], 0.07 [0.02], P <.001, respectively), independent of age, sex, ethnicity, and total intracranial volume. While age was associated with the size of most subsegmental regions of the cerebral cortex, telomere length was associated with certain subsegmental regions. Compared with age, telomere length (TL) explained a sizeable proportion of the variance in volume of the hippocampus, amygdala, and inferior temporal region (hippocampus: βTL [SE], 0.08 [0.02], R2, 0.91% vs βage [SE], -0.16 [0.02], R2, 3.80%; amygdala: βTL [SE], 0.08 [0.02], R2, 0.78% vs βage [SE],-0.19 [0.02], R2,4.63%; inferior temporal: βTL [SE], 0.07 [0.02], R2, 0.92% vs βage [SE], -0.14 [0.02], R2, 3.98%) (P <.001 for all). The association of telomere length and the size of the inferior and superior parietal, hippocampus, and fusiform regions was stronger in individuals older than 50 years than younger individuals (inferior parietal: β>50 [SE], 0.13 [0.03], P <.001 vs β≤50 [SE], 0.02 [0.02], P = .51, P for interaction = .001; superior parietal: β>50 [SE], 0.11 [0.03], P <.001 vs β≤50 [SE], 0.01 [0.02], P = .71, P for interaction = .004; hippocampus: β>50 [SE], 0.10 [0.03], P = .004 vs β≤50 [SE], 0.05 [0.02], P = .07, P for interaction = .04; fusiform: β>50 [SE], 0.09 [0.03], P = .002, β≤50 [SE], 0.03 [0.02], P = .31, P for interaction = .03). The volume of the hippocampus, amygdala, superior and inferior temporal, precuneus, lateral orbitofrontal, posterior cingulate, thalamus and ventral diencephalon were independently associated with telomere length after adjustment for all covariates (age, gender, ethnicity, total intracranial volume, body mass index, blood pressure, diabetes, smoking status, and APOE genotype). To our knowledge, this is the first population-based study to date to evaluate telomere length as an independent predictor of global and regional brain size. Future studies are needed to determine how telomere length and anatomic structural changes are related to cognitive function, dementia, and psychological disease.

Immune senescence and cancer in elderly patients: Results from an exploratory study

BackgroundThe challenge of immune senescence has never been addressed in elderly cancer patients. This study compares the thymic output and peripheral blood telomere length in ≥70year old cancer patients. Patients and methodsFifty-two elderly cancer patients and 39 age-matched controls without personal history of cancer were enrolled. All patients underwent a Comprehensive Geriatric Assessment (CGA), from which a multidimensional prognostic index (MPI) score was calculated. Peripheral blood samples were studied for naïve and recent thymic emigrant (RTE) CD4+ and CD8+ cells by flow cytometry. T-cell receptor rearrangement excision circle (TREC) levels, telomere length and telomerase activity in peripheral blood cells were quantified by real-time PCR. ResultsThe percentages of CD8+ naïve and CD8+ RTE cells and TREC levels were significantly lower in cancer patients than in controls (p=0.003, p=0.004, p=0.031, respectively). Telomere lengths in peripheral blood cells were significantly shorter in cancer patients than in controls (p=0.046) and did not correlate with age in patients, whereas it did in controls (r=−0.354, p=0.031). Short telomere (≤median)/low TREC (≤median) profile was associated with higher risk of cancer (OR=3.68 [95% CI 1.22–11.11]; p=0.021). Neither unfitness on CGA nor MPI score were significantly related to thymic output or telomere length in either group. ConclusionsImmune senescence is significantly worse in elderly cancer patients than in age-matched controls. The low thymic output and the shorter telomeres in peripheral blood cells of cancer patients may reflect a pre-existing condition which facilitates the onset of malignancies in elderly people.