Restoration of impaired lysosomal function mitigates drusen-like deposit formation and cell death in Malattia Leventinese
Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa
Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa
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Research Article Cell biology Ophthalmology

Restoration of impaired lysosomal function mitigates drusen-like deposit formation and cell death in Malattia Leventinese

Abstract

Malattia Leventinese (MAL) is an inherited macular degeneration disorder characterized by retinal drusen formation in adolescence, leading to vision loss. A mutation in the fibulin-3 gene (EFEMP1) causes MAL; however, the mechanisms underlying disease onset and drusen formation remain unclear. In this study, we generated induced pluripotent stem cell–derived retinal pigment epithelial (iPSC-RPE) cells from a patient with MAL to investigate disease mechanisms and potential therapies. MAL iPSC-RPE exhibited fibulin-3 and apolipoprotein E (ApoE) aggregation, increased endoplasmic reticulum stress, and enhanced apoptosis. Long-term culture with photoreceptor outer segments led to drusen-like deposits containing ApoE, complement components, and collagen IV accumulation, and it showed activation of matrix metalloproteinase-2 (MMP2). Untargeted lipid analysis revealed increased hexosylceramide and bis-monoacylglycerophosphate levels in MAL iPSC-RPE cells. A key pathological feature was lysosomal dysfunction associated with altered regulation of lysosomal gene programs, including reduced transcription factor EB transcript levels. Treatment with trehalose, a lysosome-modulating compound, increased lysosomal content and function, reducing drusen-like deposit formation, inhibiting MMP2 activation, and suppressing apoptosis. This study highlighted lysosomal dysfunction as a contributor to RPE damage, drusen-like deposit accumulation, and extracellular matrix degradation. Pharmacological restoration of lysosomal function alleviated these defects, suggesting therapeutic potential for MAL and other drusen-related diseases, including age-related macular degeneration.

Authors

Yumi Inoue, Hanako O. Ikeda, Masayuki Hata, Yuto Iida, Keiko Okamoto-Furuta, Isao Asaka, Makoto Arita, Akitaka Tsujikawa

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Figure 4

Increased hexosylceramide and bis-monoacylglycerophosphate levels in MAL iPSC-RPE cells revealed by lipidomic analyses.

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Increased hexosylceramide and bis-monoacylglycerophosphate levels in MAL...
iPSC-RPE cells were cultured for 4 weeks, followed by an additional 4 weeks of incubation in the presence or absence of POS. (A–D) Quantitative analysis of lipid species intensity and total lipid abundance using untargeted liquid chromatography–mass spectrometry and statistical analysis of NOR and MAL iPSC-RPE cells. (A and B) Hexosylceramide. (C and D) Bis-monoacylglycerophosphate (BMP). (E) Immunostaining of cross-sections of NOR and MAL iPSC-RPE cells treated with POS for lysobisphosphatidic acid (LBPA, red), phalloidin (green), and DAPI (blue). Scale bar: 20 μm. (F and G) Expression levels of phospholipase D family member 3 (PLD3, F) and α/β hydrolase domain containing 6 (ABHD6, G). The y axis represents expression levels in log2 TPM (transcripts per million). (H) Comparison of intracellular free cholesterol levels. *P < 0.05, **P < 0.01, ***P < 0.005; 1-way ANOVA followed by the Tukey-Kramer test (A–D, F, and G), a linear mixed-effects model followed by Tukey’s HSD test in (H), n = 3. Data are shown as mean ± SD.