High-intensity interval training modulates retinal microvascular phenotype and DNA methylation of p66^Shc gene: a randomized controlled trial (EXAMIN AGE)

Lukas Streese^1†, AbdulWaheed Khan^2†, Arne Deiseroth¹, Shafaat Hussain², Rosa Suades², Andre Tiaden³, Diego Kyburz³, Francesco Cosentino²*, and Henner Hanssen¹

¹Department of Sport, Exercise and Health, Medical Faculty, University of Basel, Birsstrasse 320 B, 4052 Basel, Switzerland; ²Cardiology Unit, Department of Medicine Solna, Karolinska Institute, Karolinska Universitetssjukhuset, Solna S1:02 171 76 Stockholm, Sweden; and ³Department of Rheumatology, University Hospital, University of Basel, Spitalstrasse 21/ Petersgraben 4, 4031 Basel, Switzerland

* Corresponding author. Tel: +46 8 517 75 398, Fax: +46 8 34 49 64, Email: [email protected]

^† Lukas Streese and Abdul Waheed Khan contributed equally to this work.

Aims Impairments of retinal vessel diameter are associated with major adverse cardiovascular (CV) events. Promoter DNA methylation is a repressor of the mitochondrial adaptor p66^Shc gene transcription, a key driver of ageing-induced reactive oxygen species. The study aimed to investigate whether high-intensity interval training (HIIT) affects retinal microvascular phenotype as well as p66^Shc expression and oxidative stress in ageing subjects with increased CV risk from the EXAMIN AGE cohort.

Methods and results Eighty-four sedentary subjects (mean age 59.4 ± 7.0 years) with ≥2 CV risk factors were randomized into either a 12-week HIIT or standard physical activity recommendations. Retinal arteriolar and venular diameters were measured by use of a retinal vessel analyser. As a marker of oxidative stress plasma 3-nitrotyrosine (3-NT) level was determined by ELISA. Gene expression of p66^Shc and DNA methylation were assessed in mononuclear cells by RT-qPCR and methylated-DNA capture (MethylMiner Enrichment Kit) coupled with qPCR, respectively. High-intensity interval training reduced body mass index, fat mass, low-density lipoprotein and increased muscle mass, as well as maximal oxygen uptake (VO₂max). Moreover, HIIT restored microvascular phenotype by inducing retinal arteriolar widening (pre: 175 ± 14 µm vs. post: 181 ± 13 µm, P = 0.001) and venular narrowing (pre: 222 ± 14 µm vs. post: 220 ± 14 µm, P = 0.007). After HIIT, restoration of p66^Shc promoter methylation (P = 0.034) reduced p66^Shc gene expression (P = 0.037) and, in turn, blunted 3-NT plasma levels (P = 0.002).

Conclusion High-intensity interval training rescues microvascular dysfunction in ageing subjects at increased CV risk. Exercise-induced reprogramming of DNA methylation of p66^Shc gene may represent a putative mechanistic link whereby exercise protects against age-related oxidative stress.

Clinical trial registration  ClinicalTrials.gov: NCT02796976 (https://clinicaltrials.gov/ct2/show/NCT02796976).

Keywords Ageing • Retinal microcirculation • Oxidative stress • p66Shc gene • DNA methylation • Exercise

Take home figure Exercise-induced improvement of microvascular phenotype and reprogramming of p66^Shc DNA methylation. High-intensity interval training improves microvascular phenotype. Reprogramming of DNA methylation mark on p66^Shc gene promoter may represent a mechanistic link whereby physical exercise protects against age-related oxidative stress in the microcirculation.