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Lutein Leads to a Decrease of Factor D Secretion by Cultured Mature Human Adipocytes
Yuan Tian1, Aize Kijlstra1, Johan Renes2
1University Eye Clinic Maastricht, Postbus 5800, 6202 AZ Maastricht, Netherlands.
Insights
Lutein supplementation may lower circulating factor D (FD) levels by inhibiting its production in fat cells. This finding could explain previous observations in age-related macular degeneration (AMD) patients.
Area of Science:
- Ophthalmology
- Immunology
- Nutritional Science
Background:
- Age-related macular degeneration (AMD) pathogenesis involves the complement system.
- Factor D (FD), a key enzyme in the complement alternative pathway, is decreased by lutein supplementation.
- Adipose tissue synthesizes FD and stores lutein.
Purpose of the Study:
- To investigate if lutein affects factor D (FD) synthesis in adipocytes.
- To explore the mechanism behind reduced circulating FD levels after lutein supplementation.
Main Methods:
- Mature human adipocytes were cultured and treated with lutein (50 μg/mL).
- Factor D (FD) mRNA and protein expression were measured after 24 and 48 hours of incubation.
Main Results:
- Lutein significantly inhibited FD mRNA expression in adipocytes.
- Lutein reduced FD protein release into the cell culture supernatant.
Conclusions:
- Lutein may block adipocyte production of factor D (FD).
- This inhibition could explain the observed decrease in circulating FD levels in individuals supplemented with lutein, potentially impacting AMD progression.
Abstract:
Purpose. Complement plays an important role in the pathogenesis of age related macular degeneration (AMD) and trials are currently being conducted to investigate the effect of complement inhibition on AMD progression. We previously found that the plasma level of factor D (FD), which is the rate limiting enzyme of the complement alternative pathway, was significantly decreased following lutein supplementation. FD is synthesized by adipose tissue, which is also the main storage site of lutein. In view of these findings we tested the hypothesis whether lutein could affect FD synthesis by adipocytes. Methods. A cell line of mature human adipocytes was incubated with 50 μg/mL lutein for 24 and 48 h, whereafter FD mRNA and protein expression were measured. Results. Lutein significantly inhibited adipocyte FD mRNA expression and FD protein release into adipocyte culture supernatants. Conclusions. Our earlier observations showing that a daily lutein supplement in individuals with early signs of AMD lowered the level of circulating FD might be caused by blocking adipocyte FD production.
