A new study published in the Proceedings of the National Academy of Sciences explains how cigarette smoke can accelerate aging in the eye and help cause age-related macular degeneration (AMD). AMD is the leading worldwide cause of visual impairment and blindness among people age 50 and older, and people who smoke are four times more likely to develop AMD than non-smokers.
The researchers used experiments in mice and tests of donated human retinal pigmented epithelial (RPE) cells. They compared RPE cells from 3-month and 12-month mice after both acute and chronic cigarette smoke exposure, noting that those mouse ages roughly correspond to young adulthood and late middle age in humans. The team injected cigarette smoke condensate and sampled cells three, six, and ten days later, and they also examined mice exposed to smoke daily for four months. Using genetic sequencing, they identified dysfunctional RPE clusters and measured chromatin accessibility. Chromatin is the condensed DNA–RNA–protein structure that determines which genes are turned on or off.
Acute exposure produced dysfunctional RPE clusters with lower expression of core RPE function genes, reduced chromatin accessibility, and decreased expression of so-called "hallmarks of aging" genes. These hallmarks include processes such as genomic instability, shortening of chromosome ends (telomeres), and disruption of mitochondria. The molecular changes mirrored characteristics seen in human AMD and a distinct subset of aging genes appeared only in dysfunctional cells of young mice. Similar differences were seen after four months of daily smoke exposure.
In tests of donated human RPE cells—from two people without AMD who did not smoke, one person without AMD who smoked, and one person with early AMD—the team identified 1,698 genes with shared changes between dysfunctional human and mouse RPE cells. The researchers say these shared genes may be relevant to AMD development and progression. Handa said the next steps are to determine which changes are temporary and which are permanent and to study how age and continuous smoke exposure contribute to eye damage and comorbidities in late-stage AMD. The study was supported by the National Institutes of Health, the Research to Prevent Blindness Stein Innovation Award, and a BrightFocus Foundation macular degeneration research grant. Handa is on the scientific advisory boards for Character Biosciences, Cirrus Pharmaceuticals, and Seeing Medicines.
Difficult words
- age-related macular degeneration — disease causing vision loss in older adults
- chromatin accessibility — how accessible DNA is inside cells
- cigarette smoke condensate — liquid particles collected from burned tobacco smoke
- genetic sequencing — reading the order of DNA letters
- hallmark — a typical process that shows biological aginghallmarks of aging
- genomic instability — frequent changes or damage in the genome
- telomere — protective end of a chromosome that shortenstelomeres
- mitochondrion — cell structure that produces most of energymitochondria
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How do the combined mouse experiments and tests of donated human cells strengthen the evidence linking smoking to AMD? Give specific examples from the article.
- Based on the study's findings, what practical actions could people take to reduce their risk of AMD? Explain your reasons.
- What further research would you prioritize to decide which cellular changes are temporary versus permanent? Describe one study you would design and why.
Related articles
African leaders urged to fix health financing at UNGA80
At the 80th UN General Assembly in New York, Obinna Ebirim urges African countries to press for fairer donor partnerships and to increase domestic health funding. He highlights staff shortages, weak infrastructure and the National Health Fellows Programme.
Diet may help exercise for people with high blood sugar
A study in mice found a high‑fat, low‑carbohydrate ketogenic diet can lower high blood sugar and change muscles so they respond better to aerobic exercise. Researchers say diet and exercise together give the greatest benefit and people still need testing.
Keeping healthy habits during the holidays
The holiday season often disrupts regular health routines. Samantha Harden of Virginia Tech recommends realistic, small changes—like habit stacking, gamifying activities, involving others and travel tips—and a broader view of well‑being so breaks are not failure.
Plague and the role of human fleas in Madagascar
The plague is still endemic in some countries, including Madagascar. Researchers found that the human flea Pulex irritans contributes to outbreaks and that household conditions and insecticide use influence flea levels and control efforts.
Needle-free spray delivers last-resort antibiotics
Researchers developed a needle-free spray-mist device to push last-resort antibiotics through the skin into infected tissue. The method aims to treat drug-resistant infections while reducing organ damage linked to intravenous delivery.