Role of telomeres and associated maintenance genes in Type 2 Diabetes Mellitus: A review

Hidradenitis suppurativa associated telomere-methylome dysregulations in blood

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic debilitating disease with a significant burden of both organic and psychological comorbidities. It has been shown that certain telomere-related genes (TRGs) affect a wide range of diseases, including HS and its associated comorbidities, but their exact role in HS pathogenesis is still unknown.

OBJECTIVES

To determine whether TRG methylomes can be used as biomarkers in HS.

METHODS

Using the Illumina HumanMethylation450 BeadChip array, we examined methylation variations associated with TRGs in HS cases and age-, sex- and ethnicity-matched healthy controls. The study utilized integrated bioinformatics statistical methods, such as a false discovery rate (FDR), the area under the receiver operating characteristic curve (AUC) and principal component analysis.

RESULTS

There were a total of 585 different differentially methylated CpG sites identified in 585 TRGs associated with HS (474 hypomethylated and 111 hypermethylated) (FDR p-value < 0.05). A number of these CpGs have been identified as being involved in increased pain sensitivity including EPAS1, AHR, CSNK1D, DNMT1, IKBKAP, NOS3, PLCB1 and PRDM16 genes; GABRB3 as a potential alcohol addiction marker; DDB1, NSMCE2 and HNRNPA2B1 associated with cancers. Pathway analysis identified 67 statistically significant pathways, including DNA repair, telomere maintenance, mismatch repair and cell cycle control (p < 0.001).

CONCLUSION

The disruption of TRGs leads to the shortening of telomeres, which is associated with HS progression, ageing, cellular senescence and an increased risk of various diseases, including cancer and associated comorbidities, such as metabolic syndrome, cardiovascular disease and inflammatory disorders. Further research is necessary to better understand the underlying mechanisms and establish causal links between TRGs and HS. The present study is the first effort to comprehend potential pathomechanisms of sporadic HS cases concentrating on PBMC methylome since ours.

Associations between telomere attrition, genetic variants in telomere maintenance genes, and non-small cell lung cancer risk in the Jammu and Kashmir population of North India

BACKGROUND

Telomeres are repetitive DNA sequences located at the ends of chromosomes, playing a vital role in maintaining chromosomal integrity and stability. Dysregulation of telomeres has been implicated in the development of various cancers, including non-small cell lung cancer (NSCLC), which is the most common type of lung cancer. Genetic variations within telomere maintenance genes may influence the risk of developing NSCLC. The present study aimed to evaluate the genetic associations of select variants within telomere maintenance genes in a population from Jammu and Kashmir, North India, and to investigate the relationship between telomere length and NSCLC risk.

METHODS

We employed the cost-effective and high-throughput MassARRAY MALDI-TOF platform to assess the genetic associations of select variants within telomere maintenance genes in a population from Jammu and Kashmir, North India. Additionally, we used TaqMan genotyping to validate our results. Furthermore, we investigated telomere length variation and its relation to NSCLC risk in the same population using dual-labeled fluorescence-based qPCR.

RESULTS

Our findings revealed significant associations of TERT rs10069690 and POT1 rs10228682 with NSCLC risk (adjusted p-values = 0.019 and 0.002, respectively), while TERF2 rs251796 and rs2975843 showed no significant associations. The TaqMan genotyping validation further substantiated the associations of TERT rs10069690 and rs2242652 with NSCLC risk (adjusted p-values = 0.02 and 0.003, respectively). Our results also demonstrated significantly shorter telomere lengths in NSCLC patients compared to controls (p = 0.0004).

CONCLUSION

This study highlights the crucial interplay between genetic variation in telomere maintenance genes, telomere attrition, and NSCLC risk in the Jammu and Kashmir population of North India. Our findings suggest that TERT and POT1 gene variants, along with telomere length, may serve as potential biomarkers and therapeutic targets for NSCLC in this population. Further research is warranted to elucidate the underlying mechanisms and to explore the potential clinical applications of these findings.

Telomeres in clinical diabetes research - Moving towards precision medicine in diabetes care?

The early prediction of health outcomes for people with diabetes mellitus is desirable, as are adjunct therapies to reduce the related chronic complications and risk of premature death. The length of telomeres, protective caps on chromosome ends, is influenced by genetic and acquired factors, and shorter telomeres have been associated with and predictive of adverse cardiometabolic outcomes. Many studies have shown associations between telomere length in white blood cells (WBC) and diabetes per se and its chronic complications, and some studies show that telomeres do not always progressively shorten in people with diabetes. With the pandemic of diabetes and taking into consideration the calculations of residual risk using existent risk equations, additional tests to stratify subject risk are desirable. In this evolving era of precision medicine for people with diabetes, this 'global biomarker' of WBC telomere length may be useful to help predict health outcomes, to monitor health status, and may be a therapeutic target. We comment on the field of telomere investigations in diabetes, including recommending areas for further clinical research.

Lifespan and telomere length variation across populations of wild-derived African killifish

Telomeres and telomerase prevent the continuous erosion of chromosome-ends caused by lifelong cell division. Shortened telomeres are associated with age-related pathologies. While short telomere length is positively correlated with increased lethality at the individual level, in comparisons across species short telomeres are associated with long (and not short) lifespans. Here, we tested this contradiction between individual and evolutionary patterns in telomere length using African annual killifish. We analysed lifespan and telomere length in a set of captive strains derived from well-defined wild populations of Nothobranchius furzeri and its sister species, N. kadleci, from sites along a strong gradient of aridity which ultimately determines maximum natural lifespan. Overall, males were shorter-lived than females, and also had shorter telomeres. Male lifespan (measured in controlled laboratory conditions) was positively associated with the amount of annual rainfall in the site of strain origin. However, fish from wetter climates had shorter telomeres. In addition, individual fish which grew largest over the juvenile period possessed shorter telomeres at the onset of adulthood. This demonstrates that individual condition and environmentally-driven selection indeed modulate the relationship between telomere length and lifespan in opposite directions, validating the existence of inverse trends within a single taxon. Intraindividual heterogeneity of telomere length (capable to detect very short telomeres) was not associated with mean telomere length, suggesting that the shortest telomeres are controlled by regulatory pathways other than those that determine mean telomere length. The substantial variation in telomere length between strains from different environments identifies killifish as a powerful system in understanding the adaptive value of telomere length.

Telomere Attrition With Concomitant hTERT Overexpression Involved in the Progression of Gastric Cancer May Have Prognostic and Clinical Implications in High-Risk Population Group From North India

Genetic instabilities exacerbated by the dysfunction of telomeres can lead to the development of cancer. Nearly 90% of all human malignancies are linked with telomere dysregulation and overexpression of telomerase, an enzyme that catalyzes the synthesis of telomeric DNA repeats at the ends of chromosomes. The burden of gastric cancer continues to inflict a deterring impact on the global health scenario, accounting for over one million new cases in 2020. The disease is asymptomatic in its early stages of progression, which is attributed to the poor prognosis and overall surge in mortality rate worldwide. Exploiting telomere physiology can provide extensive mechanistic insight into telomere-associated gastric cancer progression and its use as a target in a variety of therapeutic interventions. In this study, we aimed to evaluate the clinical implications of c-Myc, human telomerase reverse transcriptase (hTERT) expression, and telomere length in patients with gastric cancer. A total of 57 gastric cancer cases and adjacent controls were included in the study. RT-PCR and immunohistochemistry were used to assess the expression levels of c-Myc and hTERT. The relative telomere length was measured by MMQPCR using the Cawthon method. Our results indicated that the shorter telomere and increased hTERT expression were associated with gastric cancer progression. The study also highlighted the role of short telomeres and increased expression of hTERT in gastric cancer progression and its association with various etiological risk factors, transcriptional activators, and overall survival among the ethnic Kashmiri population of North India.

Shortened leukocyte telomere length as a potential biomarker for predicting the progression of atrial fibrillation from paroxysm to persistence in the short-term

This study aimed to assess the role of leukocyte telomere length (LTL) in the development of atrial fibrillation (AF) among Chinese patients.This is a cross-sectional study. A total of 350 patients from June 2016 to December 2017 were retrospectively analyzed. These included 219 AF patients and 131 with sinus rhythm in the control group. Quantitative real-time PCR was used to measure relative LTL.The relative LTLs of all subjects (n = 350) ranged from 0.4 to 2.41 (0.98 ± 0.29), showing a significant negative correlation (P < .001) with age. The AF-group had significantly shorter LTLs (0.93 ± 0.26 vs 1.07 ± 0.33, P < .001) and were older (61.50 ± 6.49 vs 59.95 ± 6.17, P = .028) than controls. LTLs among patients with persistent AF (PsAF), paroxysmal AF (PAF), and controls were significantly different (P < .001), with LTLs of PsAF patients being the shortest and controls being the longest. After adjusting for possible confounding factors, the PsAF group still showed significantly shorter LTLs than the PAF and control groups (P = .013 and P = .001, respectively). After an 18-month follow-up, 20 out of 119 PAF patients had progressed into PsAF and a relative LTL of ≤0.73 was an independent predictor for progression of PAF into PsAF.LTL was found to be shorter in patients with AF than in age-matched individuals with sinus rhythm and positively correlated with severity of AF. LTL shortening could be an independent risk factor for progression from paroxysmal AF to persistent AF in the short term.

Association of matrix metalloproteinase-2 gene polymorphisms with susceptibility to type 2 diabetes: A case control study

AIMS

Genetic variations mediating MMP-2 expression may result in individual differences in susceptibility to particular diseases. Our aim was to investigate the possible association of certain MMP-2 gene variants with the susceptibility of type 2 diabetes (T2D) in a Tunisian population.

SUBJECTS AND METHODS

A retrospective case-control study involving 310 normoglycemic control subjects and 791 T2D patients was conducted. Genotyping of MMP-2 variants was performed by real time PCR.

RESULTS

Minor allele frequencies (MAF) of the rs243865 and the rs243866 MMP-2, were significantly different between T2D cases and controls. Setting homozygous wild-type genotype carrier as reference, a reduced risk of T2D was seen with the rs243865 and the rs243866 genotypes. Haploview analysis revealed limited linkage disequilibrium between the tested MMP-2 and variants, with most haplotypes (99.5%) captured by 7 MMP-2 haplotypes. Taking the GCCC haplotype as reference for MMP-2 (OR = 1.00), a reduced frequency of TTCC haplotypes (P = 0.04) and the GTCC haplotype (P = 3.5 · 10^-5) was noted in T2D which indicates a protective nature of these two haplotypes for T2D development.

CONCLUSION

To the best of our knowledge, the present study is the first to demonstrate a consistent association of the rs243865 and rs243866 genotype with a protection for T2D.

Idiopathic pulmonary fibrosis beyond the lung: understanding disease mechanisms to improve diagnosis and management

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disorder with an estimated median survival time of 3–5 years after diagnosis. This condition occurs primarily in elderly subjects, and epidemiological studies suggest that the main risk factors, ageing and exposure to cigarette smoke, are associated with both pulmonary and extrapulmonary comorbidities (defined as the occurrence of two or more disorders in a single individual). Ageing and senescence, through interactions with environmental factors, may contribute to the pathogenesis of IPF by various mechanisms, causing lung epithelium damage and increasing the resistance of myofibroblasts to apoptosis, eventually resulting in extracellular matrix accumulation and pulmonary fibrosis. As a paradigm, syndromes featuring short telomeres represent archetypal premature ageing syndromes and are often associated with pulmonary fibrosis. The pathophysiological features induced by ageing and senescence in patients with IPF may translate to pulmonary and extrapulmonary features, including emphysema, pulmonary hypertension, lung cancer, coronary artery disease, gastro-oesophageal reflux, diabetes mellitus and many other chronic diseases, which may lead to substantial negative consequences in terms of various outcome parameters in IPF. Therefore, the careful diagnosis and treatment of comorbidities may represent an outstanding chance to improve quality of life and survival, and it is necessary to contemplate all possible management options for IPF, including early identification and treatment of comorbidities.

Cell Therapy for Critical Limb Ischemia: Advantages, Limitations, and New Perspectives for Treatment of Patients with Critical Diabetic Vasculopathy

PURPOSE OF REVIEW

To provide a highlight of the current state of cell therapy for the treatment of critical limb ischemia in patients with diabetes.

RECENT FINDINGS

The global incidence of diabetes is constantly growing with consequent challenges for healthcare systems worldwide. In the UK only, NHS costs attributed to diabetic complications, such as peripheral vascular disease, amputation, blindness, renal failure, and stroke, average £10 billion each year, with cost pressure being estimated to get worse. Although giant leaps forward have been registered in the scope of early diagnosis and optimal glycaemic control, an effective treatment for critical limb ischemia is still lacking. The present review aims to provide an update of the ongoing work in the field of regenerative medicine. Recent advancements but also limitations imposed by diabetes on the potential of the approach are addressed. In particular, the review focuses on the perturbation of non-coding RNA networks in progenitor cells and the possibility of using emerging knowledge on molecular mechanisms to design refined protocols for personalized therapy. The field of cell therapy showed rapid progress but has limitations. Significant advances are foreseen in the upcoming years thanks to a better understanding of molecular bottlenecks associated with the metabolic disorders.

The Interplay of the Genetic Architecture, Aging, and Environmental Factors in the Pathogenesis of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing lung disease of indeterminate etiology and limited therapeutic options. The initiation, development, and progression of IPF are influenced by genetic predisposition, aging, and host and environmental factors, but the magnitude of the contribution of each of them and the sequence of the pathogenic events are uncertain. Current evidence indicates that accumulated environmental exposures in a genetically predisposed individual, usually over 60 years of age, leads to phenotypic and functional alterations of the lung epithelium. Aberrant activation of epithelial cells results, through a complex release of numerous mediators, in the local expansion of peculiar subsets of aggressive fibroblasts and myofibroblasts, which are crucial effector cells of fibrotic remodeling and loss of the normal lung architecture and function. Progressive increase of the mechanical stiffness activates cell-autonomous and matrix-dependent processes contributing to the perpetuation of the fibrotic response. This Perspective provides an integral overview of the major risk factors underpinning the pathogenesis of IPF, including gene variants, aging alterations, environmental factors, host risk factors, and epigenetic reprogramming.

Shortening of the leucocytes' telomeres length in T2DM independent of age and telomerase activity

AIMS

This study aimed to examine the role of plasma telomerase (TE), plasma insulin, patient's age and disease duration in determination of the leucocytes' telomeres length (LTL) in T2DM.

METHODS

Blood samples from Kuwaiti patients with T2DM (110) and non-diabetic subjects (94) were analyzed by SYBR Green Quantitative PCR for estimation of the Absolute Human Telomere Length and by ELISA for estimation of the TE activity and insulin level. The body mass index (BMI) and HOMA-IR were calculated.

RESULTS

The results revealed marked shortening of the LTL in T2DM compared with the non-diabetic subjects (6.068, 2.276-11.652 vs. 10.979, 6.495-23.402 kb), p < 0.001, while the TE concentration was comparable between the two groups (3.16, 0.00-6.02 vs. 4.16, 1.38-7.94 U/L, respectively), p 0.100. Importantly, in T2DM the LTL did not vary significantly with the disease duration (1 month to 40 years), p 0.959, and did not correlate with age, BMI, insulin-resistance, or glycemic parameters. Interestingly, there was a positive correlation between the LTL and insulin levels in T2DM (CC 0.211, p 0.0419). Finally, in non-diabetic subjects, HbA1c ≥ 6% was associated significantly with shorter LTL, this observation together with the lack of association of the LTL with the disease duration, suggests a causal role of short telomeres in T2DM development.

CONCLUSIONS

This study confirmed the LTL shortening in T2DM in Kuwaiti Arabs, and showed that the LTL was independent of age and TE activity but positively influenced by insulin levels. Furthermore, the study suggested that telomeres shortening could be a risk factor for T2DM.

Dual labeled fluorescence probe based qPCR assay to measure the telomere length

Telomeres are highly repetitive regions capping the chromosomes and composed of multiple units of hexa-nucleotides, TTAGGG, making their quantification difficult. Most of the methods developed to estimate telomeres are extensively cumbersome or expensive. The quantitative polymerase chain reaction (qPCR) based assay is relatively easy and cheaper method that applies SyBr Green dye chemistry to measure telomere length. SyBr Green dye fluoresces after intercalation into the double stranded DNA (dsDNA), thus detection of unspecific products has been a limitation as it may affect quantitation of telomeres. To overcome this limitation of SyBr Green dye, we developed a dual labeled fluorescence probe based quantitative polymerase chain reaction (qPCR) to measure the telomere length. This highly efficient, yet cost effective and easy method, utilizes a probe that targets primarily the telomeric DNA and this increases accuracy of an existing qPCR method.

The influence of TERC, TERT and ACYP2 genes polymorphisms on plasma telomerase concentration, telomeres length and T2DM

Telomeres are duplex tandem repeats of DNA sequence 5'-TTAGGG-3' at chromosomal ends synthesized by telomerase enzyme (TE). Telomeres length (TL) shortening is associated with age and age-related disorders. Recently, we demonstrated marked leukocytes TL (LTL) shortening in T2DM. To set the relationship between the TE, LTL and T2DM, we analyzed samples from 212 Kuwaiti subjects, 112 patients withT2DM and 100 non-diabetic subjects. The plasma TE and fasting insulin were measured by ELISA, the LTL was estimated by qPCR and three SNPs of genes related to TL; TERC rs12696304 (C/G), TERT rs2736100 (C/A) and ACYP2 rs6713088 (C/G) were genotyped by rtPCR. Results revealed comparable TE levels and alleles/genotypes between the cases and controls with no influence of either on the LTL. Interestingly, although the plasma concentration of the TE was generally low, it was significantly influenced by the TERT and ACYP2 but not TERC polymorphisms. The CC genotype carriers of rs2736100 (C/A) had significantly higher plasma TE levels compared to CA and AA carriers, p 0.009 and p 0.047, respectively, and the A-allele was associated with low TE, p 0.018. Similarly, significantly higher TE levels were detected in CC carriers of ACYP2 rs6713088 (C/G) compared with GC carriers, p 0.002, and the G-allele was associated with low TE, p 0.009. Finally, the TERT and ACYP2 polymorphisms had an influence on blood glucose levels. In conclusion, the telomeres shortening in T2DM was not due to TE deficiency or gene polymorphisms, while the TE levels were significantly associated with the TERT and ACYP2 but not TERC polymorphisms.

Analogous telomeres shortening and different metabolic profile: hypertension versus hypertension/type 2 diabetes mellitus comorbidity

Background

Eukaryotes chromosomal ends are capped and protected by telomeres, which are noncoding DNA repeats synthesized by telomerase enzyme. The telomerase enzyme is a nucleoprotein encoded by TERC and TERT genes. Naturally, the length of the telomeres shortens with each cell cycle but the shortening is fastened in certain age-related diseases like hypertension (HTN) and type 2 diabetes mellitus (T2DM).

Materials and methods

Blood samples (n = 171) were obtained from Kuwaiti subjects with HTN, and HTN/T2DM comorbidity (HTN-DM) and healthy subjects. The leukocyte telomere length (LTL) was measured by SYBR green quantitative rtPCR, and plasma telomerase enzyme was measured by ELISA, in addition, three single nucleotide polymorphisms (SNPs) in telomere-related genes; TERC rs12696304GC, TERT rs2736100CA, and ACYP2 rs6713088GC were genotyped by real-time PCR.

Results

Marked LTL shortening in subjects with HTN and HTN-DM compared to healthy subjects, P = 0.043 and P < 0.001, respectively, was noticed. On the contrary, the plasma telomerase enzyme levels and minor allele frequencies and genotypes of the tested SNPs were comparable between the study groups, except for TERT (CA) genotype which was over-represented in HTN (P = 0.037). Furthermore, the comparisons between HTN and HTN-DM revealed significantly higher total cholesterol (P = 0.015) and LDL-C (P = 0.008) in HTN, while higher insulin levels (P < 001), HOMA-IR (P < 001), and BMI (P = 0.004) were observed in HTN-DM.

Conclusion

This study showed comparable LTL shortening in HTN and HTN-DM, irrespective of plasma telomerase enzyme levels or tested TERC, TERT, and ACYP2 gene polymorphisms, although HTN and HTN-DM differed in several metabolic markers. More studies are required to affirm these observations.

Telomere Maintenance Genes are associated with Type 2 Diabetes Susceptibility in Northwest Indian Population Group

Telomere length attrition has been implicated in various complex disorders including Type 2 Diabetes (T2D). However, very few candidate gene association studies have been carried out worldwide targeting telomere maintenance genes. In the present study, variants in various critical telomere maintenance pathway genes for T2D susceptibility in Northwest Indian population were explored. With case-control candidate gene association study design, twelve variants from seven telomere maintenance genes were evaluated. Amongst these five variants, rs9419958 (OBFC1), rs4783704 (TERF2), rs16847897 (TERC/LRRC31), rs10936599 (TERC/MYNN), and rs74019828 (CSNK2A2) showed significant association with T2D (at p-value ≤ 0.003, threshold set after Bonferroni correction) in the studied population. In silico analyses of these variants indicated interesting functional roles that warrant experimental validations. Findings showed that variants in telomere maintenance genes are associated with pathogenesis of T2D in Northwest Indian population. We anticipate further, such candidate gene association studies in other Indian populations and worldwide would contribute in understanding the missing heritability of T2D.

Vitamin D metabolites influence expression of genes concerning cellular viability and function in insulin producing β-cells (INS1E).Gene. 2020;746:144649. [PMID: 32251702 DOI: 10.1016/j.gene.2020.144649]

BACKGROUND

Studies have shown that vitamin D can enhance glucose-stimulated insulin secretion (GSIS) and change the expression of genes in pancreatic β-cells. Still the mechanisms linking vitamin D and GSIS are unknown.

MATERIAL AND METHODS

We used an established β-cell line, INS1E. INS1E cells were pre-treated with 10 nM 1,25(OH)₂vitamin D or 10 nM 25(OH)vitamin D for 72 h and stimulated with 22 mM glucose for 60 min. RNA was extracted for gene expression analysis.

RESULTS

Expression of genes affecting viability, apoptosis and GSIS changed after pre-treatment with both 1,25(OH)₂vitamin D and 25(OH)vitamin D in INS1E cells. Stimulation with glucose after pre-treatment of INS1E cells with 1,25(OH)₂vitamin D resulted in 181 differentially expressed genes, whereas 526 genes were differentially expressed after pre-treatment with 25(OH)vitamin D.

CONCLUSION

Vitamin D metabolites may affect pancreatic β-cells and GSIS through changed gene expression for genes involved in β-cell function and viability.

Early life tobacco exposure and children's telomere length: The HELIX project

Telomere length and mitochondrial DNA content are considered biomarkers of cellular aging, oxidative stress, and inflammation, but there is almost no information on their association with tobacco smoke exposure in fetal and early life. The aim of this study was to assess whether prenatal and childhood tobacco exposure were associated with leukocyte telomere length (LTL) and mitochondrial DNA (mtDNA) content in children. As part of a multi-centre European birth cohort study HELIX (Human Early-Life Exposome) (n = 1396) we assessed maternal smoking status during pregnancy through questionnaires, and through urinary cotinine levels that were then used to classify women as not exposed to smoking (<10 µg/L), exposed to secondhand smoke (SHS) (10-50 µg/L) and active smokers (>50 µg/L). When the children were around 8 years of age (range: 5.4-12.0 years), childhood SHS tobacco smoke exposure was assessed through an extensive questionnaire and through measurements of urinary cotinine (<3.03 µg/L non-detected, >3.03 µg/L detected). Leukocyte mtDNA content and LTL were measured in the children at 8 years employing real time polymerase chain reaction (qPCR). Effect estimates were calculated using multivariate linear regression models for prenatal and childhood exposures adjusted for potential confounders. Maternal cotinine levels indicative of SHS exposure during pregnancy were associated with a decrease of 3.90% in LTL in children (95% CI: -6.68, -0.91), compared with non-smoking, whereas the association for maternal cotinine levels indicative of active smoking did not reach statistical significance (-3.24%; 95% CI: -6.59, 0.21). Childhood SHS tobacco exposure was not associated with LTL in children. Global SHS exposure during childhood was associated with an increase of 3.51% (95% CI: 0.78, 6.27) in mtDNA content. Our findings suggest that tobacco smoke exposure during pregnancy, even at SHS levels, may accelerate telomere shortening in children and thus induce biological aging from an early age.

Association between common telomere length genetic variants and telomere length in an African population and impacts of HIV and TB

Prior studies in predominantly European (Caucasian) populations have discovered common genetic variants (single nucleotide polymorphisms, SNPs) associated with leukocyte telomere length (LTL), but whether these same variants affect LTL in non-Caucasian populations are largely unknown. We investigated whether six genetic variants previously associated with LTL (TERC (rs10936599), TERT (rs2736100), NAF1 (7675998), OBFC1 (rs9420907), ZNF208 (rs8105767), and RTEL1 (rs755017)) are correlated with telomere length (TL) in peripheral blood mononuclear cells (PBMCs) in a cohort of Africans living with and without HIV and undergoing evaluation for tuberculosis (TB). We found OBFC1 and the genetic sum score of the effect alleles across all six loci to be associated with shorter TL (adjusted for age, gender, HIV status, and smoking pack-years (p < 0.02 for both OBFC1 and the genetic sum score). In an analysis stratified by HIV status, the genetic sum score is associated with LTL in both groups with and without HIV. On the contrary, a stratified analysis according to TB status revealed that in the TB-positive subgroup, the genetic sum score is not associated with LTL, whereas the relationship remains in the TB-negative subgroup. The different impacts of HIV and TB on the association between the genetic sum score and LTL indicate different modes of modification and suggest that the results found in this cohort with HIV and TB participants may not be applied to the African general population. Future studies need to carefully consider these confounding factors.

Association of newly identified genetic variant rs2853677 of TERT with non-small cell lung cancer and leukemia in population of Jammu and Kashmir, India

BACKGROUND

Telomere genetics has recently been emerged as an important field in molecular oncology. Various genome-wide association studies in different population groups have revealed that polymorphisms in Telomere maintenance gene (TERT) gene located on 5p15.33 is associated with susceptibility to leukemia and lung cancer risk. However, association of TERT with leukemia and lung cancer risk in north Indian population groups is still unknown. This study observed the association between genetic variant rs2853677 of TERT and leukemia and lung cancer in the state of Jammu and Kashmir, India.

METHODS

A total of 781 subjects, out of which 381 cases (203 leukemic patients and 178 non-small cell lung cancer patients NSCLC) and 400 healthy controls were recruited for the study. Genetic variant rs2853677of TERT was detected using the real-time and Taqman Chemistry. Hardy-Weinberg Equilibrium was assessed using the chi square test. The allele and genotype- specific risks were estimated as odds ratio with 95% confidence interval.

RESULTS

We observed that variant rs2853677 was strongly associated with lung cancer and leukemia risk with an odds ratio (OR) =1.8 (1.03-3.2 at 95% CI); p value (adjusted) = 0.03; odds ratio (OR) =2.9 (1.4-5.5.at 95% CI); p value (adjusted) = 0.002, respectively.

CONCLUSION

The results of this study suggested that rs2853677 of TERT signifies association in multiple cancers and suggests that it can become potential marker for diagnosis of non-small cell lung cancer and leukemia. The study will provide an insight in understanding the genetic etiology and highlights the role of telomere-associated pathways in non-small cell lung cancer and leukemia. However, it would be quite interesting to explore the contribution of this variant in other cancers as well.

Leucocyte Telomere Length and Glucose Tolerance Status in Mixed-Ancestry South Africans

Telomeres are DNA-tandem repeats situated at the ends of chromosomes and are responsible for genome stabilization. They are eroded by increased cell division, age and oxidative stress with shortened leucocyte telomeres (LTL) being associated with inflammatory disorders, including Type II diabetes. We assessed LTL in 205 participants across glucose tolerance groups at baseline and after three years in the mixed ancestry population of South Africa which have been shown to have high rates of obesity and T2DM. Baseline and follow-up data included glucose tolerance status, anthropometric measurements, lipids, insulin, γ-glutamyl transferase (GGT), cotinine, and HbA1c. Telomere length was measured using the absolute telomere q-PCR method performed on a Bio-Rad MiniOpticon Detector. No significant difference was detected in LTL across glucose tolerance groups at both time points, including in subjects who showed a deterioration of their glucose tolerance status. There was, however, a significant negative correlation between LTL and age which was more pronounced in diabetes (r = −0.18, p = 0.04) and with GGT (r = −0.16, p = 0.027). This longitudinal study has demonstrated that LTL shortening is not evident within three years, nor is it associated with glycaemia. Further studies in a larger sample and over a longer time period is required to confirm these results.

Early Senescence and Leukocyte Telomere Shortening in SCHIZOPHRENIA: A Role for Cytomegalovirus Infection?

Schizophrenia is a severe, chronic mental disorder characterized by delusions and hallucinations. Several evidences support the link of schizophrenia with accelerated telomeres shortening and accelerated aging. Thus, schizophrenia patients show higher mortality compared to age-matched healthy donors. The etiology of schizophrenia is multifactorial, involving genetic and environmental factors. Telomere erosion has been shown to be accelerated by different factors including environmental factors such as cigarette smoking and chronic alcohol consumption or by psychosocial stress such as childhood maltreatment. In humans, telomere studies have mainly relied on measurements of leukocyte telomere length and it is generally accepted that individuals with short leukocyte telomere length are considered biologically older than those with longer ones. A dysregulation of both innate and adaptive immune systems has been described in schizophrenia patients and other mental diseases supporting the contribution of the immune system to disease symptoms. Thus, it has been suggested that abnormal immune activation with high pro-inflammatory cytokine production in response to still undefined environmental agents such as herpesviruses infections can be involved in the pathogenesis and pathophysiology of schizophrenia. It has been proposed that chronic inflammation and oxidative stress are involved in the course of schizophrenia illness, early onset of cardiovascular disease, accelerated aging, and premature mortality in schizophrenia. Prenatal or neonatal exposures to neurotropic pathogens such as Cytomegalovirus or Toxoplasma gondii have been proposed as environmental risk factors for schizophrenia in individuals with a risk genetic background. Thus, pro-inflammatory cytokines and microglia activation, together with genetic vulnerability, are considered etiological factors for schizophrenia, and support that inflammation status is involved in the course of illness in schizophrenia.

Emerging role of nutrition and the non-coding landscape in type 2 diabetes mellitus: A review of literature

With the advent of recent advances in molecular techniques and whole genome sequencing, we have come to know that the non-coding landscape (including non-coding RNAs, tRNAs and even telomeres) plays a major role in the regulation of cellular processes. Furthermore, the deregulation of this landscape has been found to contribute to and even bring about the pathogenesis of a large number of diseases. One of such diseases is diabetes mellitus (type 2 specifically) whose incidence rate and global burden is constantly increasing. Nutrition has been proven to be a key player in the development, onset and control of type 2 diabetes mellitus. Additionally, non-coding DNA based molecular markers are emerging as biomarkers of T2D, susceptibility, and perhaps dietary supplements can modulate non-coding DNA based markers expression and function in T2D management. In this review, we provide a brief overview of the developmental origins and genetics of type 2 diabetes mellitus, how each component of the non-coding landscape contributes to the development and progression of the disease and finally we discuss how dietary interventions modulate the non-coding landscape in T2D.

State of the Science: Using Telomeres as Biomarkers During the First 1,000 Days of Life

Telomere biology shows promise as an integrative biomarker of exposures and increased occurrence of chronic disease and early mortality. This integrative review examined the state of the science regarding toxicokinetic risks and maternal factors in humans and in vivo models that are correlated with telomere length during the first 1,000 days of life. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses framework assisted in guiding this integrative by aiding researchers in identifying, selecting, and critically appraising the literature. Ovid MEDLINE, CINAHL, Cochrane Systematic Reviews, Web of Science, and SCOPUS databases were searched. The initial search yielded a total of 381 published articles. Full-text screening resulted in 19 articles retained for review (14 quasi-experimental studies and five experimental studies). Findings suggest a relationship between toxicokinetic exposures creating inflammation or oxidative stress (i.e., smoking) and maternal health conditions such as sleep apnea to shorter telomere length in children below 2 years old.

Leukocyte telomere length correlates with glucose control in adults with recently diagnosed type 2 diabetes

AIMS

We investigated leukocyte relative telomere length (TL) in patients with type 2 diabetes (T2D) diagnosed for no longer than five years and its association with clinical and biochemical variables.

METHODS

Peripheral blood leukocyte relative TL was investigated in 108 patients with T2D (87 women, 21 men) and 125 (37 women, 88 men) age-matched control subjects with normal glucose tolerance, by quantitative polymerase chain reaction. Multiple linear regression analysis was used to examine the association between relative TL and demographic, anthropometric and biochemical indicators of metabolic control among patients with T2D.

RESULTS

Patients with T2D had a median time since diagnosis of 1 year and most were on metformin monotherapy, with satisfactory glucose control determined by HbA1c levels. Median relative TL was not different between patients with T2D and control subjects. However, multiple linear regression analyses showed that relative TL was inversely associated with time since T2D diagnosis, fasting plasma glucose levels and HbA1c levels, but not with HbA1c levels assessed in the preceding 5-12 months, after adjustment for age, sex and body mass index.

CONCLUSION

This study suggests that relative TL is not shorter in patients with recently diagnosed T2D, but is inversely correlated with glucose levels, even among patients with overall satisfactory glucose control.

Idiopathic pulmonary fibrosis: Clinical behavior and aging associated comorbidities

Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible and usually lethal lung disease of unknown etiology. Once considered as a relatively homogeneous, slowly progressive disease, is now recognized that the clinical behavior shows substantial heterogeneity, including an accelerated variant, and the presence of acute exacerbations. In addition, since IPF largely affects individuals over 60 years of age, the patients are at increased risk of several comorbidities that in turn have a remarkable clinical impact on the disease and increases mortality rate. Among others, combined pulmonary fibrosis and emphysema, secondary pulmonary arterial hypertension, lung cancer, and cardiovascular diseases are frequently associated with IPF and impact survival. For these reasons clinical phenotypes and comorbidities should be timely identified and managed. The aim of this review is to describe the common pulmonary and extra-pulmonary comorbidities in IPF, as well as the putative mechanisms involved.