Premature telomere shortening in polymorphonuclear neutrophils from patients with systemic lupus erythematosus is related to the lupus disease activity

Association of phenotypic frailty and hand grip strength with telomere length in SLE

OBJECTIVE

Frailty and objective hand grip strength (one of the components of the frailty phenotype) are both risk factors for worse health outcomes in SLE. Whether telomere length, an established cellular senescence marker, is a biologic correlate of the frailty phenotype and hand grip strength in patients with SLE is not clear. First, we aimed to evaluate differences in telomere length between frail and non-frail women with SLE and then assessed whether frailty or hand grip strength is differentially associated with telomere length after adjusting for relevant confounders.

METHODS

Women ≥18 years of age with validated SLE enrolled at a single medical centre. Fried frailty status (which includes hand grip strength), clinical characteristics and telomere length were assessed cross-sectionally. Differences between frail and non-frail participants were evaluated using Fisher's exact or Wilcoxon rank-sum tests. The associations between frailty and hand grip strength and telomere length were determined using linear regression.

RESULTS

Of the 150 enrolled participants, 131 had sufficient data for determination of frailty classification; 26% were frail with a median age of 45 years. There was a non-significant trend towards shorter telomere length in frail versus non-frail participants (p=0.07). Hand grip strength was significantly associated with telomere length (beta coefficient 0.02, 95% CI 0.004, 0.04), including after adjustment for age, SLE disease activity and organ damage, and comorbidity (beta coefficient 0.02, 95% CI 0.002, 0.04).

CONCLUSIONS

Decreased hand grip strength, but not frailty, was independently associated with shortened telomere length in a cohort of non-elderly women with SLE. Frailty in this middle-aged cohort may be multifactorial rather than strictly a manifestation of accelerated ageing.

Telomere length and its association with systemic lupus erythematosus in an Asian population: A Mendelian randomization study

OBJECTIVES

To investigate whether shorter telomere length is a causal risk factor for systemic lupus erythematosus (SLE) in the Asian population.

METHODS

We applied the two-sample Mendelian randomization (MR) method to the pooled statistics from a genome-wide association study (GWAS) of 6,707 SLE cases and 16,047 controls. We selected nine single-nucleotide polymorphisms (SNPs) with genome-wide significance as instrumental variables for telomere length. The main analysis was carried out by the random-effects inverse-variance weighted (IVW) method. Horizontal pleiotropy was evaluated by the intercept of MR-Egger regression.

RESULTS

A potentially causal relationship between longer genetically predicted telomere length and increased risk of systemic lupus erythematosus (OR = 1.72, 95%CI: 1.21, 2.46, p = 0.01) was observed. The MR-Egger regression demonstrated an intercept proximal to zero (intercept = 0.017, p = 0.69), which does not provide evidence of the presence of horizontal pleiotropy.

CONCLUSIONS

Our findings provided evidence supporting a potential causal relationship between longer telomere length and increased risk of systemic lupus erythematosus.

Telomere length, oxidative and epigenetic changes in blood DNA of patients with exacerbated psoriasis vulgaris

BACKGROUND

The pathogenesis of psoriasis vulgaris involves changes in DNA molecules, genomic instability, telomere attrition, and epigenetic alterations among them. These changes are also considered important mechanisms of aging in cells and tissues.

OBJECTIVE

This study dealt with oxidation damage, telomere length and methylation status in DNA originating from peripheral blood of 41 psoriatic patients and 30 healthy controls.

METHODS

Oxidative damage of serum DNA/RNA was determined immunochemically. Real-time PCR was used for the analysis of the telomere length. ELISA technique determined levels of 5-methylcytosine in blood cells' DNA.

RESULTS

Oxidative damage of serum DNA/RNA was higher in patients than in controls (median, 3758 vs. 2286pg/mL, p<0.001). A higher length of telomeres per chromosome was found in patients whole-cell DNA than in controls (3.57 vs. 3.04 kilobases, p=0.011). A negative correlation of the length of telomeres with an age of the control subjects was revealed (Spearman's rho=-0.420, p=0.028). Insignificantly different levels of 5-methylcytosine in patients and controls were observed (33.20 vs. 23.35%, p=0.234). No influences of sex, smoking, BMI, PASI score, and metabolic syndrome on the methylation status were found.

STUDY LIMITATIONS

i) A relatively small number of the participants, particularly for reliable subgroup analyses, ii) the Caucasian origin of the participants possibly influencing the results of the parameters determined, and iii) Telomerase activity was not directly measured in serum or blood cells.

CONCLUSION

The study demonstrated increased levels of oxidized DNA/RNA molecules in the serum of patients with exacerbated psoriasis vulgaris. The results were minimally influenced by sex, the presence of metabolic syndrome, or cigarette smoking. In the psoriatic blood cells' DNA, the authors observed longer telomeres compared to healthy controls, particularly in females. Insignificantly higher global DNA methylation in psoriasis cases compared to the controls indicated marginal clinical importance of this epigenetic test performed in the blood cells' DNA.

Pilot study on accelerated aging in lupus using epigenetic biomarkers of age

OBJECTIVE

Despite an important increase in lifespan over the last decades, patients with systemic lupus erythematosus (SLE) still have to face a high morbi-mortality, particularly related to cardiovascular diseases, infections and cancers. Such events are more commonly found during old age in the general population, raising the hypothesis of an acceleration of the aging process in SLE patients. In this pilot study, we wanted to test the hypothesis that SLE would be associated with an accelerated biological aging measured by the epigenetic clocks models.

METHODS

We applied DNA methylation-based biomarkers of age in publicly available datasets of SLE patients. For every SLE patient and control included in the dataset, we calculated their epigenetic age and a measure of epigenetic age acceleration, according to Horvath's epigenetic clock model.

RESULTS

We included in our analysis two distinct DNA methylation datasets of 30 subjects (among which 15 with SLE) and 55 subjects (among which 30 with SLE), respectively. In both datasets, there was a statistically significant correlation between chronological age and epigenetic age. We did not observe any statistically significant difference in the measure of epigenetic age acceleration between SLE patients and controls.

CONCLUSION

We did not observe any evidence of an accelerated biological aging in SLE patients, according to Horvath's epigenetic clock model.

Association of the PINX1 Variant rs6984094, Which Lengthens Telomeres, with Systemic Lupus Erythematosus Susceptibility in Chinese Populations

A recent genome-wide association study (GWAS) of Asian ancestry reported that single nucleotide polymorphism (SNP) in TERT (telomerase reverse transcriptase) was associated with systemic lupus erythematosus (SLE). TERT has a critical role in maintaining the chromosomal stability and the length of telomere. Given that only a small portion of the genetic heritability of SLE has been explained so far, we aimed to identify novel loci in telomere-related genes responsible for SLE susceptibility in Chinese populations. We performed a comprehensive genetic association analysis of SLE with telomere-related genes. To identify functional significance, we analyzed the publicly available HaploReg v4.1 and RegulomeDB databases. Differential gene expression analysis was also performed using ArrayExpress. A novel signal of PINX1 rs6984094 was identified (P _discovery = 4.13 × 10^-2, OR = 0.58, 95% CI 0.35-0.98) and successfully replicated (P _replication = 5.73 × 10^-3, OR = 0.45, 95% CI 0.26-0.81). Multiple layers of functional analysis suggested that the PINX1 rs6984094 risk T allele exhibited increased nuclear protein binding. We also observed an increased expression of PINX1 mRNA in peripheral blood mononuclear cells from SLE patients compared with healthy controls. Overall, we observed a novel genetic association between PINX1 (encodes the PinX1 protein, an inhibitory telomerase enzyme that lengthens telomeres) and SLE susceptibility in Chinese populations.

Sustained high expression of multiple APOBEC3 cytidine deaminases in systemic lupus erythematosus

APOBEC3 (A3) enzymes are best known for their role as antiviral restriction factors and as mutagens in cancer. Although four of them, A3A, A3B, A3F and A3G, are induced by type-1-interferon (IFN-I), their role in inflammatory conditions is unknown. We thus investigated the expression of A3, and particularly A3A and A3B because of their ability to edit cellular DNA, in Systemic Lupus Erythematosus (SLE), a chronic inflammatory disease characterized by high IFN-α serum levels. In a cohort of 57 SLE patients, A3A and A3B, but also A3C and A3G, were upregulated ~ 10 to 15-fold (> 1000-fold for A3B) compared to healthy controls, particularly in patients with flares and elevated serum IFN-α levels. Hydroxychloroquine, corticosteroids and immunosuppressive treatment did not reverse A3 levels. The A3AΔ3B polymorphism, which potentiates A3A, was detected in 14.9% of patients and in 10% of controls, and was associated with higher A3A mRNA expression. A3A and A3B mRNA levels, but not A3C or A3G, were correlated positively with dsDNA breaks and negatively with lymphopenia. Exposure of SLE PBMCs to IFN-α in culture induced massive and sustained A3A levels by 4 h and led to massive cell death. Furthermore, the rs2853669 A > G polymorphism in the telomerase reverse transcriptase (TERT) promoter, which disrupts an Ets-TCF-binding site and influences certain cancers, was highly prevalent in SLE patients, possibly contributing to lymphopenia. Taken together, these findings suggest that high baseline A3A and A3B levels may contribute to cell frailty, lymphopenia and to the generation of neoantigens in SLE patients. Targeting A3 expression could be a strategy to reverse cell death and the generation of neoantigens.

Impact of Delaying Antiretroviral Treatment during Primary HIV Infection on Telomere Length

BACKGROUND

Telomere length (TL) shortens during aging, HIV-seroconversion and untreated chronic HIV infection. It is unknown whether early antiretroviral therapy (ART) start is associated with less TL shortening during primary HIV infection (PHI).

METHODS

We measured TL in peripheral blood mononuclear cells by quantitative PCR in participants of the Zurich PHI Study with samples available for >6 years. We obtained uni-/multivariable estimates from mixed-effects models and evaluated the association of delaying ART start or interrupting ART with baseline and longitudinal TL.

RESULTS

In 105 participants with PHI (median age 36 years, 9% women), median ART delay was 25, 42, and 60 days, respectively, in the 1 st (shortest), 2 nd, and 3 rd (longest) ART delay tertile. First ART delay tertile was associated with longer baseline TL (p for trend=0.034), and longer TL over 6 years, but only with continuous ART (p<0.001), not if ART was interrupted >12 months (p=0.408). In multivariable analysis, participants in the 2 nd and 3 rd ART delay tertile had 17.6% (5.4-29.7%; p=0.004) and 21.5% (9.4-33.5%; p<0.001) shorter TL, after adjustment for age, with limited effect modification by clinical variables.

DISCUSSION

In PHI, delaying ART start for even a matter of weeks was associated with significant and sustained TL shortening.

Telomere dysfunction promotes small vessel vasculitis via the LL37-NETs-dependent mechanism

Background

Small vessel vasculitis (SVV) is a group of systemic autoimmune diseases that are mediated by neutrophil extracellular traps (NETs) in response to cathelicidin LL37, an aging molecular marker, which could be induced by telomere dysfunction. Therefore, in this study, we evaluated the hypothesis that telomere dysfunction in neutrophils may promote SVV via an LL37-NETs-dependent mechanism.

Methods

We contrasted the release of neutrophil NETs from mice with telomere dysfunction, mice with DNA damage and wide-type mice. Neutrophil telomere length, the expression of LL37, and the formation of NETs were measured in SVV patients and healthy controls (HCs). The co-expression of γH2AX, LL37, and NETs were detected in SVV patients to evaluate the association of the immune aging of neutrophils and pro-inflammatory conditions. LL37 inhibitor was used to verify its key role in NETs release in SVV patients and DNA damage mice.

Results

We found that NETs were over-induced by telomere dysfunction and DNA damage in mice, which may be associated with a marked increase in LL37. For patients with SVV, telomeres in neutrophils were significantly shortened, which was also associated with higher levels of LL37 and NETs. Inhibition of LL37 reduced the NETs released from neutrophils.

Conclusions

Taken together, the results of these studies suggest that dysfunction of telomeres may promote SVV through the mechanism of LL37-dependent NETs. Thus, targeting the LL37-NETs may be a novel therapy for SVV.

Molecular and Cellular Bases of Immunosenescence, Inflammation, and Cardiovascular Complications Mimicking "Inflammaging" in Patients with Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an archetype of systemic autoimmune disease, characterized by the presence of diverse autoantibodies and chronic inflammation. There are multiple factors involved in lupus pathogenesis, including genetic/epigenetic predisposition, sexual hormone imbalance, environmental stimulants, mental/psychological stresses, and undefined events. Recently, many authors noted that "inflammaging", consisting of immunosenescence and inflammation, is a common feature in aging people and patients with SLE. It is conceivable that chronic oxidative stresses originating from mitochondrial dysfunction, defective bioenergetics, abnormal immunometabolism, and premature telomere erosion may accelerate immune cell senescence in patients with SLE. The mitochondrial dysfunctions in SLE have been extensively investigated in recent years. The molecular basis of normoglycemic metabolic syndrome has been found to be relevant to the production of advanced glycosylated and nitrosative end products. Besides, immunosenescence, autoimmunity, endothelial cell damage, and decreased tissue regeneration could be the results of premature telomere erosion in patients with SLE. Herein, the molecular and cellular bases of inflammaging and cardiovascular complications in SLE patients will be extensively reviewed from the aspects of mitochondrial dysfunctions, abnormal bioenergetics/immunometabolism, and telomere/telomerase disequilibrium.

Association of chronic fatigue syndrome with premature telomere attrition

Background

Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a severely debilitating condition of unknown etiology. The symptoms and risk factors of ME/CFS share features of accelerated aging implicated in several diseases. Using telomere length as a marker, this study was performed to test the hypothesis that ME/CFS is associated with accelerated aging.

Methods

Participant (n = 639) data came from the follow-up time point of the Georgia CFS surveillance study. Using the 1994 CFS Research Case Definition with questionnaire-based subscale thresholds for fatigue, function, and symptoms, participants were classified into four illness groups: CFS if all criteria were met (n = 64), CFS-X if CFS with exclusionary conditions (n = 77), ISF (insufficient symptoms/fatigue) if only some criteria were met regardless of exclusionary conditions (n = 302), and NF (non-fatigued) if no criteria and no exclusionary conditions (n = 196). Relative telomere length (T/S ratio) was measured using DNA from whole blood and real-time PCR. General linear models were used to estimate the association of illness groups or T/S ratio with demographics, biological measures and covariates with significance set at p < 0.05.

Results

The mean T/S ratio differed significantly by illness group (p = 0.0017); the T/S ratios in CFS (0.90 ± 0.03) and ISF (0.94 ± 0.02) were each significantly lower than in NF (1.06 ± 0.04). Differences in T/S ratio by illness groups remained significant after adjustment for covariates of age, sex, body mass index, waist–hip ratio, post-exertional malaise and education attainment. Telomere length was shorter by 635, 254 and 424 base pairs in CFS, CFS-X and ISF, respectively, compared to NF. This shorter telomere length translates to roughly 10.1–20.5, 4.0–8.2 and 6.6–13.7 years of additional aging in CFS, CFS-X and ISF compared to NF respectively. Further, stratified analyses based on age and sex demonstrated that the association of ME/CFS with short telomeres is largely moderated by female subjects < 45 years old.

Conclusions

This study found a significant association of ME/CFS with premature telomere attrition that is largely moderated by female subjects < 45 years old. Our results indicate that ME/CFS could be included in the list of conditions associated with accelerated aging. Further work is needed to evaluate the functional significance of accelerated aging in ME/CFS.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1414-x) contains supplementary material, which is available to authorized users.

The shortening telomere length of T lymphocytes maybe associated with hyper‑function in servere aplastic anemia

Severe aplastic anemia (SAA) is a primary disorder of severe bone marrow failure characterizing with extreme pancytopenia and a profound diminution of bone marrow progenitor cells, which is associated with T cell hyper‑function. Abnormal telomere shortening of bone marrow mononuclear cell has been reported in AA, which may lead to genomic instability, and result in cell senescence or apoptosis. Notably, certain studies identfieid that lymphocytes of shortening telomere length have undergone apoptosis escape in autoimmune diseases. In order to investigate the association between telomere lengths and function of T lymphocytes in SAA, the relative telomere lengths (RTLs) of different subtypes of T lymphocytes were investigated by flow‑fluorescent in situ hybridization in 30 patients with SAA and 25 healthy controls. Then the levels of expression of cluster of differentiation 28 (CD28), CD158 and CD70 were measured, which represent the function of T lymphocytes. The apoptosis rate and the cell cycle progression of CD8+T lymphocytes, and the level of secretion interferon‑γ and tumor necrosis factor‑α were also measured. Finally, the correlation between telomere length and these functional events of CD8+T lymphocytes was analyzed in patients with SAA. The results showed that RTLs of CD8+T lymphocytes in SAA were significantly shorter compared with those in controls. Furthermore, in patients with SAA, CD8+T lymphocytes are associated with T cell hyper‑function, which is related to the RTL. Thus, the shorter RTLs of CD8+T lymphocytes in SAA may be associated with hyper‑function of these cells, which contribute to the pathogenesis of SAA.

Assessment of Telomere Length, Phenotype, and DNA Content

Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior cell separation. After cells are stained for surface immunofluorescence, antigen-antibody complexes are covalently cross-linked onto cell membranes before FISH with a telomere-specific probe. Cells with long telomeres are included as internal standards. Addition of a DNA dye permits exclusion of proliferating cells during data analysis. DNA ploidy measurements of cells of interest and internal standard are performed on separate aliquots in parallel to Flow-FISH. Telomere fluorescence of G0/1 cells of subpopulations and internal standards obtained from Flow-FISH are normalized for DNA ploidy, and telomere length in subsets of interest is expressed as a fraction of the internal standard telomere length. © 2017 by John Wiley & Sons, Inc.

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

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

Association between shortened telomere length and systemic lupus erythematosus: a meta-analysis

Objective We aimed to evaluate the relationship between telomere length and systemic lupus erythematosus (SLE). Methods PUBMED and EMBASE databases were searched; meta-analyses were performed comparing telomere length in SLE patients and healthy controls, and on SLE patients in subgroups based on ethnicity, sample type, assay method and data type. Results Eight studies including 472 SLE patients and 365 controls were ultimately selected which showed that telomere length was significantly shorter in the SLE group than in the control group (standardized mean difference (SMD) = -0.835, 95% confidence interval (CI) = -1.291 to -0.380, p = 3.3 × 10^-4). Stratification by ethnicity showed significantly shortened telomere length in the SLE group in Caucasian, Asian and mixed populations (SMD = -0.455, 95% CI = -0.763 to -0.147, p = 0.004; SMD = -0.887, 95% CI = -1.261 to -0.513, p = 3.4 × 10^-4; SMD = -0.535, 95% CI = -0.923 to -0.147, p = 0.007; respectively). Furthermore, telomere length was significantly shorter in the SLE group than in the control group in whole blood and peripheral blood mononuclear cell groups (SMD = -0.361, 95% CI = -0.553 to -0.169, p = 2.3 × 10^-4; SMD = -1.546, 95% CI = -2.583 to -0.510, p = 0.003; respectively); a similar trend was observed in leukocyte groups (SMD = -0.699, 95% CI = -1.511 to -0.114, p = 0.092). Meta-analyses based on assay method or data type revealed similar associations. Conclusions Our meta-analysis demonstrated that telomere length was significantly shorter in patients with SLE, regardless of ethnicity, sample type or assay method evaluated.

Soluble CD163 is associated with shortened telomere length in HIV-infected patients

Telomere length (TL) and immune activation markers were measured in a cohort of HIV-infected (n = 102) and age-matched non-HIV-infected (n = 41) men. TL was significantly shorter in HIV-infected compared with non-HIV-infected subjects (P = 0.04). Univariate analysis revealed a strong inverse relationship of TL to sCD163, and thus, monocyte/macrophage activation, among the HIV group (ρ = -0.30, P = 0.003). In multivariate modeling among the whole group, HIV-positive serostatus (P = 0.06) and sCD163 (P = 0.05) remained predictors of TL controlling for age and smoking status. Our data demonstrate that increased immune activation relates to shorter TL in HIV.

The effect of pro-inflammatory conditioning and/or high glucose on telomere shortening of aging fibroblasts

Cardiovascular disease and diabetes have been linked to shorter telomeres, but it is not yet clear which risk factors contribute to shorter telomeres in patients. Our aim was to examine whether pro-inflammatory conditioning, in combination or not with high glucose, result in a higher rate of telomere shortening during in vitro cellular ageing. Human fibroblasts from four donors were cultured for 90 days in: 1) medium lacking ascorbic acid only, 2) 10 mM buthionine sulphoximine (BSO) (pro-oxidant), 3) 25 mM D-glucose, 4) 1 ng/ml IL1B and 5) 25 mM D-glucose+1 ng/ml IL1B. Telomere length was measured with qPCR and intracellular reactive oxygen species (ROS) content and cell death with flow cytometry. Cultures treated with high glucose and BSO displayed a significantly lower growth rate, and cultures treated with IL1B showed a trend towards a higher growth rate, compared to the control [Glucose:0.14 PD/day, p<0.001, BSO: 0.11 PD/day, p = 0.006 and IL1B: 0.19 PD/day, p = 0.093 vs.

CONTROL

0.16 PD/day]. Telomere shortening with time was significantly accelerated in cultures treated with IL1B compared to the control [IL1B:-0.8%/day (95%CI:-1.1, -0.5) vs.

CONTROL

-0.6%/day (95%CI:-0.8, -0.3), p = 0.012]. The hastening of telomere shortening by IL1B was only in part attenuated after adjustment for the number of cell divisions [IL1B:-4.1%/PD (95%CI:-5.7, -2.4) vs.

CONTROL

-2.5%/PD (95%CI:-4.4, -0.7), p = 0.067]. The intracellular ROS content displayed 69% increase (p = 0.033) in BSO compared to the control. In aging fibroblasts, pro-inflammatory conditioning aggravates the shortening of telomeres, an effect which was only in part driven by increased cell turnover. High glucose alone did not result in greater production of ROS or telomere shortening.

Telomere shortening in human diseases

The discovery of telomeres dates back to the early 20th century. In humans, telomeres are heterochromatic structures with tandem DNA repeats of 5'-TTAGGG-3' at the chromosomal ends. Telomere length varies greatly among species and ranges from 10 to 15 kb in humans. With each cell division, telomeres shorten progressively because of the 'end-replication problem'. Short or dysfunctional telomeres are often recognized as DNA DSBs, triggering cell-cycle arrest and result in cellular senescence or apoptotic cell death. Therefore, telomere shortening serves as an important tumor-suppressive mechanism by limiting cellular proliferative capacity by regulating senescence checkpoint activation. Although telomeres serve as a mitotic clock to cells, they also confer capping on chromosomes, with help from telomere-associated proteins. Over the past decades, many studies of telomere biology have demonstrated that telomeres and telomere-associated proteins are implicated in human genetic diseases. In addition, it has become more apparent that accelerated telomere erosion is associated with a myriad of metabolic and inflammatory diseases. Moreover, critically short or unprotected telomeres are likely to form telomeric fusions, leading to genomic instability, the cornerstone for carcinogenesis. In light of these, this minireview summarizes studies on telomeres and telomere-associated proteins in human diseases. Elucidating the roles of telomeres involved in the mechanisms underlying pathogenesis of these diseases may open up new possibilities for novel molecular targets as well as provide important diagnostic and therapeutic implications.

Shortened telomere length in patients with systemic lupus erythematosus

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) have a higher rate of premature death compared to the general population, suggesting a phenotype of premature senescence in SLE. Telomere length can be used to assess overall biologic aging. This study was undertaken to address the hypothesis that patients with SLE have reduced telomere length.

METHODS

Telomere length was measured cross-sectionally in whole blood from SLE patients and age-matched healthy female controls, using real-time quantitative polymerase chain reaction. SLE-related and cardiovascular risk factors were assessed.

RESULTS

We compared telomere length in 63 SLE patients and 63 matched controls with a median age of 50.8 years (interquartile range [IQR] 37-59 years) and 49.9 years (IQR 32-60 years), respectively. The median relative telomere length in SLE patients was 0.97 (IQR 0.47-1.57), compared to 1.53 (IQR 0.82-2.29) in controls (P = 0.0008). We then extended our cohort to measure telomere length in 164 SLE patients. Shorter telomere length was associated with Ro antibodies (β ± SE -0.36 ± 0.16; P = 0.023), and longer telomere length was associated with steroid therapy (0.29 ± 0.14; P = 0.046). We also noted an association of longer telomere length with increasing body mass index (β ± SE 0.07 ± 0.01; P < 0.0001) and tobacco smoking (0.64 ± 0.26; P = 0.016), as well as with the presence of carotid plaque (0.203 ± 0.177; P = 0.032).

CONCLUSION

Telomere length is shortened in SLE patients compared to controls and does not appear to be a reflection of disease activity or immune cell turnover. Subsets of patients such as those positive for Ro antibodies may be particularly susceptible to premature biologic aging. The predictive value of telomere length as a biomarker of future risk of damage/mortality in SLE requires longitudinal evaluation.

Systemic lupus erythematosus and vitamin D deficiency are associated with shorter telomere length among African Americans: a case-control study

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease that disproportionately affects African American females. The causes of SLE are unknown but postulated to be a combination of genetic predisposition and environmental triggers. Vitamin D deficiency is one of the possible environmental triggers. In this study we evaluated relationships between vitamin D status, cellular aging (telomere length) and anti-telomere antibodies among African American Gullah women with SLE. The study population included African American female SLE patients and unaffected controls from the Sea Island region of South Carolina. Serum 25-hydroxyvitamin D levels were measured using a nonchromatographic radioimmunoassay. Telomere length was measured in genomic DNA of peripheral blood mononuclear cells (PBMCs) by monochrome multiplex quantitative PCR. Anti-telomere antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients with SLE had significantly shorter telomeres and higher anti-telomere antibody titers compared to age- and gender-matched unaffected controls. There was a positive correlation between anti-telomere antibody levels and disease activity among patients and a significant correlation of shorter telomeres with lower 25-hydroxyvitamin D levels in both patients and controls. In follow-up examination of a subset of the patients, the patients who remained vitamin D deficient tended to have shorter telomeres than those patients whose 25-hydroxyvitamin D levels were repleted. Increasing 25-hydroxyvitamin D levels in African American patients with SLE may be beneficial in maintaining telomere length and preventing cellular aging. Moreover, anti-telomere antibody levels may be a promising biomarker of SLE status and disease activity.

Telomere length in patients with systemic lupus erythematosus and its associations with carotid plaque

OBJECTIVE

To evaluate telomere length (TL) between patients with SLE and healthy controls and to test if TL is associated with carotid plaque.

METHODS

A pilot study of 154 patients with SLE and 152 controls was performed from the SOLVABLE (Study of Lupus Vascular and Bone Long-Term Endpoints) cohort. Demographic and cardiovascular disease (CVD) factors were collected at baseline. The presence or absence of plaque was evaluated by B-mode US. Genomic DNA was isolated from whole peripheral blood. TL was quantified using real-time quantitative PCR.

RESULTS

SLE women had a short TL compared with healthy controls (4.57 vs 5.44 kb, P = 0.03). SLE women showed shorter TL than controls across all age groups: <35 years (4.38 vs 6.37 kb), 35-44 years (4.52 vs 5.30 kb), 45-54 years (4.77 vs 5.68 kb) and ≥55 years (4.60 vs 4.71 kb). Among patients with SLE and carotid plaque there was a trend towards shorter TL at a younger age and it was significantly lower in the 35- to 44-year age group when compared with controls (P = 0.025). Multiple logistic regression analysis indicated a risk of carotid plaque with older age [odds ratio (OR) 1.09; 95% CI 1.06, 1.12] but not with TL (OR 1.05; 95% CI 0.97, 1.13).

CONCLUSION

SLE women had significantly shorter TL than controls. SLE women trended towards shorter TL at a younger age. When carotid plaque was identified, the younger SLE women had shorter TL. Only older age but not shorter TL was independently associated with carotid plaque. Additional studies are needed to confirm if TL is a novel biomarker for cardiovascular disease in SLE.

Immunopathogenesis of primary biliary cirrhosis: an old wives' tale

Primary biliary cirrhosis (PBC) is a cholestatic liver disease characterised by the autoimmune destruction of the small intrahepatic bile ducts. The disease has an unpredictable clinical course, but may progress to fibrosis and cirrhosis. Although medical treatment with urseodeoxycholic acid is largely successful, some patients may progress to liver failure requiring liver transplantation. PBC is characterised by the presence of disease specific anti-mitochondrial (AMA) antibodies, which are pathognomonic for PBC development. The disease demonstrates an overwhelming female preponderance and virtually all women with PBC present in middle age. The reasons for this are unknown; however several environmental and immunological factors may be involved. As the immune systems ages, it become less self tolerant, and mounts a weaker response to pathogens, possibly leading to cross reactivity or molecular mimicry. Some individuals display immunological changes which encourage the development of autoimmune disease. Risk factors implicated in PBC include recurrent urinary tract infection in females, as well as an increased prevalence of reproductive complications. These risk factors may work in concert with and possibly even accelerate, immune system ageing, contributing to PBC development. This review will examine the changes that occur in the immune system with ageing, paying particular attention to those changes which contribute to the development of autoimmune disease with increasing age. The review also discusses risk factors which may account for the increased female predominance of PBC, such as recurrent UTI and oestrogens.

Neutrophils in the pathogenesis and manifestations of SLE

Systemic lupus erythematosus (SLE) is an autoimmune disease of unclear etiology that affects mostly women of childbearing age. Profound abnormalities in both innate and adaptive immunity triggered by genetic and environmental factors are well documented to play an important part in the pathogenesis of SLE. Nonetheless, the role of neutrophils--the most abundant immune cell type--in the pathology of this disease has been unclear. Over the past decade, compelling evidence has emerged that implicates neutrophils in the initiation and perpetuation of SLE and also in the resultant organ damage frequently observed in patients with this disease. SLE-derived low-density granulocytes (LDGs) induce vascular damage and synthesize increased amounts of type I interferons and, as such, could play a prominent part in the pathogenesis of SLE. Furthermore, increased cell death and enhanced extracellular trap formation observed in SLE-derived neutrophils might have key roles in the induction of autoimmunity and the development of organ damage in patients with SLE. Together, these events could have significant deleterious effects and promote aberrant immune responses in this disease. This Review highlights the role of neutrophils in the pathogenesis of SLE, with a particular focus on the putative deleterious effects of LDGs and neutrophil extracellular trap formation.

Changes in the expression of telomere maintenance genes might play a role in the pathogenesis of systemic lupus erythematosus

Previous studies demonstrated that telomerase activity increased while telomere length shortened in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE). This study aimed to examine the changes of telomere maintenance genes and their clinical significance in SLE. The mRNA level of telomeric proteins in PBMCs, including shelterin complex (TRF1, TRF2, POT1, TPP1, TIN2 and hRAP1), a set of multifunctional proteins involved in telomere maintenance (MRE11, KU80 and RPA1), and Ki67, was measured using real-time quantitative PCR in 56 SLE patients (36 treated and 20 untreated; 32 with renal involvement and 24 without renal involvement) and 46 healthy subjects (controls). The expression of TPP1, TIN2, POT1 and KU80 was significantly reduced while that of TRF2 and MRE11 increased in SLE patients ( p < 0.05, respectively); significant difference was not found in the expression of TRF1, hRAP1, RPA1 and Ki67 ( p > 0.05, respectively). The expression of TRF2, MRE11 and Ki67 was much higher in untreated SLE patients than in controls or treated SLE patients ( p < 0.05, respectively); the expression of hRAP1 was much higher in SLE patients with renal involvement than in controls or SLE patients without renal involvement ( p < 0.05, respectively). Significant positive correlation was found between level of KU80 and C3, TPP1 and TIN2, TPP1 and POT1, while significant negative correlation was found between KU80 and serum total globulins, TIN2 and RF, TPP1 and SLEDAI score ( p < 0.05, respectively). In conclusion, altered expression of telomere maintenance genes might be involved in the pathogenesis of SLE. Further study in expression and functions of telomeric proteins would be needed.

Immunosenescence and rheumatoid arthritis: does telomere shortening predict impending disease?

The pathogenesis of RA, a disabling autoimmune disease, is incompletely understood. Early in the development of RA there appears to be loss of immune homeostasis and regulation, and premature immunosenescence. While identification of risk factors and understanding of the phases of RA pathogenesis are advancing, means of accurately predicting an individual's risk of developing RA are currently lacking. Telomere length has been proposed as a potential new biomarker for the development of RA that could enhance prediction of this serious disease. Studies examining telomere length in relation to RA have found that telomere erosion appears to proceed more rapidly in subjects with RA than in healthy controls, and that telomere lengths are shorter in those with the RA-risk HLA-shared epitope genes. These studies have been small, however, with retrospective or cross-sectional designs. The potential role of telomere shortening as an independent biomarker for future RA risk, perhaps strongly genetically determined by HLA-SE genes, after controlling for known risk factors such as smoking, body mass index and immunosuppressant medication use, as well as systemic inflammation, is an unanswered question.

The telomere/telomerase system in autoimmune and systemic immune-mediated diseases

Telomeres are specialized nucleoproteic structures that cap and protect the ends of chromosomes. They can be elongated by the telomerase enzyme, but in telomerase negative cells, telomeres shorten after each cellular division because of the end replicating problem. This phenomenon leads ultimately to cellular senescence, conferring to the telomeres a role of biological clock. Oxidative stress, inflammation and increased cell renewal are supplementary environmental factors that accelerate age-related telomere shortening. Similar to other types of DNA damage, very short/dysfunctional telomeres activate a DNA response pathway leading to different outcomes: DNA repair, cell senescence or apoptosis. During the last 10 years, studies on the telomere/telomerase system in autoimmune and/or systemic immune-mediated diseases have revealed its involvement in relevant physiopathological processes. Here, we present a literature review of telomere and telomerase homeostasis in systemic inflammatory diseases including systemic lupus erythematosus, rheumatoid arthritis and granulomatous diseases. The available data indicate that both telomerase activity and telomere length are modified in various systemic immune-mediated diseases and appear to be connected with premature immunosenescence. Studies on the telomere/telomerase system open new research avenues for the basic understanding and for therapeutic approaches of these pathologies.

[Telomeres and telomerase: relevance and future prospects in systemic lupus erythematosus]

Telomeres are specialized structures that cap and protect the end of chromosomes. Telomeres progressively shorten after each cellular division unless an enzyme, the telomerase, counteracts. Telomeres are implicated in cellular senescence, acting like a biological clock. Telomere length and telomerase activity are important in the physiopathology of cancer. In the past years, research has focused on them in order to find new therapeutic targets. Yet, oxidative stress, inflammation and increased leucocytes renewal are major environmental factors associated with telomeres shortening acceleration and thus in concordance with biological age. Thus, telomeric erosion induces cell apoptosis; indeed, apoptotic cell clearance is impaired in systemic lupus. Considering these elements and data resulting from oncology, telomere/telomerase couple was studied during the last decade in systemic lupus erythematosus. The objective was to know if this couple could have an implication in the physiopathology of this disease. A systematic review of literature is proposed about telomere and/or telomerase in systemic lupus erythematosus in order to discuss their physiopathological implication. Among 273 tested patients, telomere seems to be eroded and telomerase activity insufficiently increased but correlated to the activity of the disease. The analysis of telomere length and telomerase activity could be useful as prognosis factor or disease activity index. Telomere erosion could reflect an accelerated replicative senescence of the immune system. The role of the regulator T lymphocytes has not yet been precised. Standardized studies on larger population could be realized in systemic lupus and open new avenues of research and/or therapy based upon the telomere/telomerase biology.

Differing patterns of peripheral blood leukocyte telomere length in rheumatologic diseases

Telomeres progressively shorten with repeated somatic tissue cell division, their length being an indicator of cellular ageing. Telomeric dysfunction may be implicated in a variety of diseases. We measured mean telomere length in peripheral blood leukocytes (PBL) from patients with various rheumatologic diseases. Mean PBL telomere length was measured using real-time quantitative polymerase chain reaction (Q-PCR) assay in a control population (n=130; age range: 3-94 years) and in subjects diagnosed with rheumatoid arthritis (RA; n=86; age range: 31-82 years), psoriatic arthritis (PA; n=56; age range: 26-79 years) and ankylosing spondylitis (AS; n=59; age range: 21-75 years). These diseases are associated with chronic systemic inflammatory activity. Telomere length was also quantified in subjects with osteoarthritis (OA; n=34; age range: 43-82 years) and osteoporosis (OP; n=35; age range: 59-95 years), diseases without a chronic systemic inflammatory component. Telomere length in OA showed no differences from age-matched controls (p=0.234), but was significantly shorter in OP (p=0.001). Telomere length was significantly longer than controls in RA (p=0.015), PA (p<0.001) and AS (p<0.001). Different patterns in telomere length from PBL are evidenced in rheumatologic pathologies, possibly dependent on the presence or absence of chronic systemic inflammation.

Telomeres and immunological diseases of aging

A defining feature of the eukaryotic genome is the presence of linear chromosomes. This arrangement, however, poses several challenges with regard to chromosomal replication and maintenance. To prevent the loss of coding sequences and to suppress gross chromosomal rearrangements, linear chromosomes are capped by repetitive nucleoprotein structures, called telomeres. Each cell division results in a progressive shortening of telomeres that, below a certain threshold, promotes genome instability, senescence, and apoptosis. Telomeric erosion, maintenance, and repair take center stage in determining cell fate. Cells of the immune system are under enormous proliferative demand, stressing telomeric intactness. Lymphocytes are capable of upregulating telomerase, an enzyme that can elongate telomeric sequences and, thus, prolong cellular lifespan. Therefore, telomere dynamics are critical in preserving immune function and have become a focus for studies of immunosenescence and autoimmunity. In this review, we describe the role of telomeric nucleoproteins in shaping telomere architecture and in suppressing DNA damage responses. We summarize new insights into the regulation of telomerase activity, hereditary disorders associated with telomere dysfunction, the role of telomere loss in immune aging, and the impact of telomere dysfunction in chronic inflammatory disease.

Assessment of telomere length, phenotype, and DNA content

Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior cell separation. After cells are stained for surface immunofluorescence, antigen-antibody complexes are covalently cross-linked onto cell membranes before FISH with a telomere-specific probe. Cells with long telomeres are included as internal standards. Addition of a DNA dye permits exclusion of proliferating cells during data analysis. DNA ploidy measurements of cells of interest and internal standard are performed on separate aliquots in parallel to Flow-FISH. Telomere fluorescence of G(0/1) cells of subpopulations and internal standards obtained from Flow-FISH are normalized for DNA ploidy and telomere length in subsets of interest is expressed as a fraction of the internal standard telomere length.

Telomere length analysis in monocytes and lymphocytes from patients with systemic lupus erythematosus using multi-color flow-FISH

In order to analyse telomere length in subsets of human peripheral blood lymphocytes and monocytes, we modified a recently developed multicolor flow- fluorescent in situ hybridization (FISH) methodology that combines flow-FISH and antibody staining for cell surface antigens. We analysed telomere length of peripheral blood mononuclear cells in a group of 22 patients with systemic lupus erythematosus (SLE) and 20 age-matched healthy donors. We found that neither CD4+, CD8+, CD19+ cells nor CD14+ monocytes have significantly shorter telomeres compared with their healthy counterparts. On the basis of these findings, we then used monocyte telomere length as internal reference in order to control for intra-individual variability in telomere length. By using this approach, we could demonstrate significant telomere shortening in all three lymphocyte subsets (in all cases P < 0.05) compared with monocytes. However, these differences did not vary significantly between SLE patients and controls. In summary, telomere lengths in subpopulations of hematopoietic cells can be monitored in patients with SLE using multicolor flow-FISH. While confirming data by other groups on telomere length in lymphocyte subpopulations, our data argue against an increased proliferation rate of peripheral blood monocytes reflected by accelerated telomere shortening in patients with SLE.