Autophagy Guided Interventions to Modify the Phenotype of Danon Disease

Dor Yadin Cardiac Surgery, Felsenstein Research Center. Rabin Medical Center, Sackler School of Medicine, Tel Aviv University, Petach Tiqwa, Israel Cardiology, Leviev Heart Center, Sheba Medical Center and Sackler School of Medicine, Tel Aviv University, Ramat Gan, Israel Zachary Petrover Cardiac Surgery, Felsenstein Research Center. Rabin Medical Center, Sackler School of Medicine, Tel Aviv University, Petach Tiqwa, Israel Life Science, Bar-Ilan university, Israel Asher Shainberg Life Science, Bar-Ilan university, Israel Dan Aravot Cardiac Surgery, Felsenstein Research Center. Rabin Medical Center, Sackler School of Medicine, Tel Aviv University, Petach Tiqwa, Israel Ronny Alcalai Cardiology, Hadassah Medical Center, University Hospital, Jerusalem, Israel Jon Seidman Genetics, Harvard Medical School, Boston, MA, USA Edith Hochhauser Cardiac Surgery, Felsenstein Research Center. Rabin Medical Center, Sackler School of Medicine, Tel Aviv University, Petach Tiqwa, Israel Michael Arad Cardiology, Leviev Heart Center, Sheba Medical Center and Sackler School of Medicine, Tel Aviv University, Ramat Gan, Israel

Background: Mutations in the lysosome-associated membrane protein-2 gene (LAMP2) produce an X-linked Danon disease (DD), manifested by ventricular hypertrophy, myocardial fibrosis, and progressive heart failure. Defects in LAMP2 impair lysosomal function and fusion thereby leading to an accumulation of autophagosomes. Mice carrying a human LAMP2^Δ6 mutation develop mild cardiac hypertrophy followed by fibrosis, dilatation and reduced systolic function. The cardiac phenotype in DD mice is aggravated by angiotensin.
Aims: We hypothesized that targeting autophagy will modify the DD phenotype.

Methods: 14-week-old LAMP2^Δ6 and control SvEv mice were treated with 4 weeks of caloric restriction (CR - 35% reduced caloric intake) or high-fat diet (HFD - 42% fat chow) protocols. Mice underwent echocardiography and were sacrificed. Myocardial fibrosis was quantitated from Masson’s Trichrome stained sections. Hydroxyproline assay for collagen, TBARS for oxidative stress, gene expression and protein analysis were performed in frozen tissue specimens.

Results: CR showed a trend for improving fractional shortening (FS) in control mice but impaired it in DD (35±10% vs 24±8%, p<0.05). Concomitantly it aggravated fibrosis in DD without significantly affecting oxidative stress. HFD did not affect the left ventricular dimensions or function in DD but induced dilated cardiomyopathy in control mice (by reducing FS 29.0±7.5 to 10.8±5.9%, P<0.05, and increasing the left ventricular diastolic dimension 3.8±0.6 to 4.3±0.6 mm). There was a significant increase in myocardial fibrosis and TBARS in HFD fed normal mice but not in DD. Pharmacological interventions to activate or inhibit autophagy by rapamycin and chloroquine, respectively, produced similar effects. Gene expression analysis indicated activation of the proteasome, endoplasmic reticulum stress and fibrosis-related genes (TGFb and CTGF) in DD. HFD reduced gene activation in DD but increased them in control mice.

Conclusions: Interventions to inhibit autophagy such as HFD and avoiding stress may attenuate disease progression in DD.

Presentation