Measurement of Telomere Length Dynamics by Flow-FISH

Scientific Reports. 2023 Jan 6; 13 (1): 304.

Authors: Rolles B, Ferreira MSV, Vieri M, Rheinwalt KP, Schmitz SM, Alizai PH, Neumann U, Brümmendorf TH, Beier F, Ulmer TF, Tometten M.

• Telomeres are the end structures of chromosomes and they have a variety of functions, including protection and stabilization of the chromosomal architecture as well as preserving the integrity and organization of the DNA.
• Obesity has negative effects on comorbidities, health-related quality of life, and survival. Telomere length (TL) changes after bariatric surgery have been reported, but the studies are contradictory, and analyses using state-of-the-art techniques for TL measurement, such as flow-FISH, are sparse.

• Patient cohort. The cohort consisted of 45 patients with obesity undergoing bariatric surgery at the Department of Surgery and Transplantation (University Hospital RWTH Aachen). The inclusion criteria were BMI ≥ 40 kg/m² or BMI ≥ 35 kg/m² with secondary diseases, minimum age of 18 years, and insufficient response during a structured conservative program for weight reduction.
• TL measurement via flow-FISH. We prepared the samples after thawing for cell denaturation and stained them with a telomere-specific (CCCTAA)3-peptide nucleic acid (PNA) FITC-labeled FISH probe for DNA hybridization, combined with DNA counterstaining. Fluorescence intensity was measured via an FC-500 using forward scatter (cell volume) and LDS 751 for identification of the cell subsets (thymocytes, lymphocytes, and granulocytes).
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• The initial absolute lymphocyte and granulocyte TL (n = 45 and n = 43, respectively) are shown in the figure. Compared to healthy controls, the lymphocyte aaTL of all patients before surgery was significantly shortened, while the granulocyte aaTL was no different. Moreover, the lymphocyte TL was significantly shorter than that of the granulocytes.

Fig. 1 Left: Absolute and age-adjusted (aa) telomere length (TL) in peripheral blood before bariatric surgery. Right: Difference (∆) of the absolute telomere length (TL) of the follow-up population after bariatric surgery (n = 35).

• We observed a significant increase in the absolute lymphocyte TL in patients with a BMI loss ≥ 10 kg/m² (n = 20; P = 0.003) compared to patients with a BMI loss < 10 kg/m² (n = 15; P = 0.54). Of note, similar findings were observed for the granulocyte TL. Here, we observed a significant increase in the absolute granulocyte TL in patients with a BMI loss ≥ 10 kg/m² (n = 18; P = 0.031) compared to patients with a less pronounced weight loss (n = 14; P = 0.64).

The study confirmed that patients suffering from obesity have significantly shorter lymphocyte TL using flow-FISH. Along with and dependent on the degree of weight reduction after bariatric surgery, TL significantly increased in both lymphocytes and granulocytes after a mean of 5.5 months. The results show that bariatric surgery affects not only body weight but also biomarkers of aging, such as TL.

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Reference

1. Rolles B, et al. (2023). "Telomere length dynamics measured by flow-FISH in patients with obesity undergoing bariatric surgery." Sci Rep. 13 (1), 304.

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