Telomeres, telomerase, and lupus: the long and short of it

The regulatory feedback of inflammatory signaling and telomere/telomerase complex dysfunction in chronic inflammatory diseases

Inflammation is believed to play a role in the progression of numerous human diseases. Research has shown that inflammation and telomeres are involved in a feedback regulatory loop: inflammation increases the rate of telomere attrition, leading to telomere dysfunction, while telomere components also participate in regulating the inflammatory response. However, the specific mechanism behind this feedback loop between inflammatory signaling and telomere/telomerase complex dysfunction has yet to be fully understood. This review presents the latest findings on this topic, with a particular focus on the detailed regulation and molecular mechanisms involved in the progression of aging, various chronic inflammatory diseases, cancers, and different stressors. Several feedback loops between inflammatory signaling and telomere/telomerase complex dysfunction, including NF-κB-TERT feedback, NF-κB-RAP1 feedback, NF-κB-TERC feedback, STAT3-TERT feedback, and p38 MAPK-shelterin complex-related gene feedback, are summarized. Understanding the latest discoveries of this feedback regulatory loop can help identify novel potential drug targets for the suppression of various inflammation-associated diseases.

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.

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.

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

We investigated whether premature telomeric loss occurred in peripheral polymorphonuclear neutrophils (PMN) as well as mononuclear cells (MNC) from patients with systemic lupus erythematosus (SLE). We measured the telomere length of MNC and PMN in 60 SLE patients and 26 sex-, race- and age-matched healthy volunteers by Southern blotting with chemiluminescence method. The possible predisposing factors associated with telomere change were also analysed. We found the telomere length of MNC and PMN shortened with age in different degrees in both SLE and control groups. Compared to the control group, the telomere length was shortened in both SLE-MNC (6.08 kb in SLE versus 6.71 kb in control, P = 0.0008) and PMN (6.24 kb in SLE versus 6.75 kb in control, P = 0.0025). The average reduction in telomere length in SLE patients was equivalent to a premature senescence of 16.5 years in MNC and 13.4 years in PMN. In addition, the accelerated telomere shortening was more prominent in SLE patients younger than 45 years old. SLE disease activity (SLEDAI) contributed remarkably to the accelerated telomere erosion, at least in PMN. Moreover, the telomere length of MNC was significantly shorter than PMN in the same SLE patients with leukopenia and lymphopenia. These data suggested that MNC and PMN from patients with SLE displayed premature and accelerated telomere shortening that SLE is an independent factor for it.

Telomerase activity and telomere length of peripheral blood mononuclear cells in SLE patients

We evaluated the clinical significance of the telomerase activity and telomere length of peripheral blood mononuclear cells (PBMC) in systemic lupus erythematosus (SLE). PBMC were isolated from 55 patients with SLE and the telomerase activity was measured by TRAP assay. The telomere length of PBMC was also measured in 30 of these subjects. As a control group, 45 healthy adults with no particular clinical history were studied. The results were compared with clinical data. In patients with active SLE, the telomerase activity of PBMC was significantly increased compared with the control group. In patients with inactive SLE, the PBMC telomerase activity was not different compared with the controls in their 20s, 30s and 40s, but it was significantly increased compared with the controls in their 50s. In SLE patients, the telomerase activity of PBMC was significantly correlated with modified SLEDAI. The telomere length of PBMC in younger SLE patients tended to be shorter than that in the controls, but no difference was observed in older patients. The correlation coefficient between the telomerase activity and telomere length of PBMC in SLE patients was not significant. Abnormalities in the telomerase activity and telomere length observed in SLE patients are considered to be important findings for evaluation of the pathology of SLE.

Telomeres and Human Aging: Facts and Fibs

Can telomere dynamics, defined by telomere length and attrition rate, provide information about the biology of human aging above and beyond that provided by chronological age? Accruing data suggest that it can. White blood cells (WBCs) have been used as the primary model in attempts to decipher links between aging, aging-related disorders, and telomere dynamics in humans. The WBC model may be appropriate in clinical settings, provided that we fully appreciate its drawbacks and limitations. On the basis of WBC telomere data, it is evident that age-adjusted telomere length is highly variable, highly heritable, longer in women than men, and shorter in people who harbor a host of age-related disorders, whose common denominators may prove to be increased oxidative stress and inflammation. It appears that shorter age-adjusted WBC telomere length augurs a greater risk of morbidity and premature mortality in the elderly. However, it is unsettled whether human telomere dynamics is only a proxy for fundamental mechanisms that govern the course of aging or a key determinant in its progression.

Helicobactor pylori infection is closely associated with telomere reduction in gastric mucosa

OBJECTIVE

To investigate differential reduction in telomere DNA in tissue components of gastric mucosa with respect to Helicobactor pylori infection.

MATERIALS AND METHODS

The telomere content was examined by fluorescent in situ hybridization with the (TTAGGG)(4) probe. To compare the signal intensities from the probe (telomere volume) with telomere length, five gastric carcinoma cell lines were used. Telomere volumes were examined in 9 healthy persons, 124 non-cancer patients, and 86 gastric cancer patients.

RESULTS

Telomere volume showed a linear correlation with telomere length measured by Southern blotting in gastric carcinoma cells. In healthy persons without H. pylori infection, the telomere volumes of gastric epithelial tissues were 70-79% that of intramucosal lymphocytes (internal control). In 124 patients without gastric cancer, telomere volume of H.-PYLORI-infected mucosa was significantly less than that of H.-pylori-negative mucosa in both metaplastic and non- metaplastic tissues (p < 0.0001). In 86 gastric cancer patients, telomere volumes in intestinal metaplasia adjacent to cancer were 75% that of intestinal metaplasia of non-cancer patients (p = 0.0001). hTERT expression was detected in 6 cancer-associated and 2 cancer-negative intestinal metaplasia specimens, in which telomere volume was markedly reduced.

CONCLUSION

H. pylori infection is closely associated with telomere reduction in gastric epithelium.