Ocular localization of circulating bacterial lipopolysaccharide

Area of Science:

• Immunology
• Microbiology
• Pharmacology

Background:

• Bacterial lipopolysaccharide (LPS) is a major component of Gram-negative bacteria.
• LPS plays a critical role in the host immune response and pathogenesis of infections.
• Understanding LPS tissue distribution is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the tissue distribution of a specific bacterial lipopolysaccharide (LPS) from Salmonella minnesota (Re595) after intravenous injection in rabbits.
• To determine if LPS preferentially accumulates in ocular tissues.

Main Methods:

• Intravenous injection of radiolabeled (125I) Salmonella minnesota Re595 LPS in rabbits.
• Quantification of LPS localization using gamma radiation spectrometry and radioautography.
• Utilized fluorescein-labeled antibody for LPS detection.
• Employed radiolabeled albumin and fibrinogen to assess vascular permeability.

Main Results:

• LPS primarily localized in the liver and spleen.
• Nanogram quantities of LPS were detected in the eye at 30 minutes post-injection.
• Increased LPS accumulation was observed in iris-ciliary processes and aqueous humor compared to the posterior segment at 2 hours.
• No histological evidence of LPS localization in iris-ciliary processes was found via radioautography or antibody staining.

Conclusions:

• LPS does not show preferential localization within the eye.
• However, LPS does accumulate in ocular tissues, specifically the iris-ciliary processes and aqueous humor.
• The localized accumulation suggests LPS may exert local effects within the eye despite not being a primary target organ.