Molecular underpinnings of induced degenerative heterogeneity in the retinal pigment epithelium.

Cigarette smoke condensate (CSC) administration to mice induced distinct healthy and dedifferentiated RPE cell clusters identifiable by snRNA-seq and single nuclear ATAC sequencing.

• Both aged vehicle-treated mice and young CSC-treated mice showed distinct healthy and dedifferentiated RPE clusters.
• The study used snRNA-seq and single nuclear ATAC sequencing (snATAC-seq) to characterize these populations.
• CSC was administered to both young and aged mice to model smoke-induced changes.
• Similar dedifferentiated and healthy RPE populations were identified in mice exposed to cigarette smoke for 4 months.

Dedifferentiated RPE cells exhibited globally decreased chromatin accessibility and reduced expression of genes linked to hallmarks of aging.

• snATAC-seq revealed globally decreased chromatin accessibility in dedifferentiated RPE clusters.
• Expression of genes linked to 'hallmarks of aging' was decreased in dedifferentiated RPE.
• This pattern was observed in both aged vehicle- and young CSC-treated mice.
• The epigenetic changes are consistent with the hypothesis that smoke induces epigenetic-mediated degenerative RPE heterogeneity.

Young dedifferentiated RPE exhibited compensatory upregulation of hallmarks of aging-related genes including mitochondrial function and proteostasis, whereas aged dedifferentiated RPE did not.

• Young, dedifferentiated RPE upregulated hallmarks of aging-related genes including those involved in mitochondrial function and proteostasis.
• Aged dedifferentiated RPE lacked this compensatory upregulation.
• The absence of this compensatory response in aged RPE was associated with decreased survival following CSC treatment.
• Decreased survival in aged dedifferentiated RPE was experimentally verified with TUNEL labeling.

Similar populations of dedifferentiated and healthy RPE were identified in human donor macular RPE from a smoker and a donor with early AMD, but not from a nonsmoker donor.

• Human donor tissue analysis identified comparable RPE heterogeneity in macular RPE from a donor who smoked.
• A donor with early AMD also showed similar dedifferentiated RPE populations.
• A nonsmoker donor did not show these dedifferentiated RPE populations.
• This finding links smoke-induced RPE heterogeneity in mice to human AMD-relevant pathology.

Cigarette smoking is a powerful risk factor for age-related macular degeneration (AMD), the leading worldwide cause of blindness among the elderly, and induces epigenetic changes that can cause degenerative heterogeneity.

• AMD is described as 'the leading worldwide cause of blindness among the elderly.'
• RPE cell heterogeneity is identified as 'a key change' in AMD.
• Cigarette smoking is described as 'a powerful risk factor for AMD.'
• The study hypothesized that smoke induces epigenetic-mediated degenerative RPE heterogeneity as a mechanism linking smoking to AMD.

Degenerative cellular heterogeneity that includes an abnormal RPE cluster can jeopardize cell survival and represents a hallmark of ocular aging.

• The presence of a dedifferentiated abnormal cluster within RPE was associated with compromised cell survival.
• This degenerative heterogeneity was identified as 'a hallmark of ocular aging.'
• TUNEL labeling was used to experimentally verify decreased survival in aged RPE following CSC treatment.
• The findings were consistent across both mouse models and human donor tissue.