Downregulation of Endotoxin-Induced Uveitis by Intravitreal Injection of Vasoactive Intestinal Peptide Encapsulated in Liposomes

• Published in: Investigative ophthalmology & visual science Vol. 48; no. 7; pp. 3230 - 3238
• Main Authors: Lajavardi, Laure, Bochot, Amelie, Camelo, Serge, Goldenberg, Brigitte, Naud, Marie-Christine, Behar-Cohen, Francine, Fattal, Elias, de Kozak, Yvonne
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01-07-2007; Association for Research in Vision and Ophtalmology
• Subjects: Animals; Aqueous Humor - metabolism; Biological and medical sciences; Cytokines - genetics; Down-Regulation; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Immunotherapy; Injections; Lipopolysaccharides; Liposomes; Lymph Nodes - metabolism; Macrophages - immunology; Male; Medical sciences; Microscopy, Confocal; Microscopy, Fluorescence; Neutrophils - immunology; Ophthalmology; Phosphatidylethanolamines; Polyethylene Glycols; Rats; Rats, Inbred Lew; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Salmonella typhimurium; Uvea diseases; Uveitis - genetics; Uveitis - metabolism; Vasoactive Intestinal Peptide - administration & dosage; Vasoactive Intestinal Peptide - pharmacokinetics; Vertebrates: nervous system and sense organs; Vitreous Body - drug effects; Vitreous Body - metabolism; Encapsulation; Toxin; Eye disease; Uveitis; Vasoactive intestinal peptide; Liposome; Vitreous body; Uvea disease; Injection; Ophthalmology; Endotoxin
• ISSN: 0146-0404; 1552-5783; 1552-5783
• DOI: 10.1167/iovs.06-1305

To reestablish the immunosuppressive microenvironment of the eye, disrupted by ocular inflammation during endotoxin-induced uveitis (EIU), by means of intravitreal injection of vasoactive intestinal peptide (VIP) in saline or encapsulated in liposomes, to increase its bioavailability and efficiency.
EIU was induced in Lewis rats by subcutaneous injection of lipopolysaccharide (LPS). Simultaneously, animals were intravitreally injected with saline, saline/VIP, VIP-loaded liposomes (VIP-Lip), or unloaded liposomes. EIU severity and cellular infiltration were assessed by clinical examination and specific immunostaining. VIP concentration was determined in ocular fluids by ELISA. Ocular expression of inflammatory cytokine and chemokine mRNAs was detected by semiquantitative RT-PCR. Biodistribution of rhodamine-conjugated liposomes (Rh-Lip) was analyzed by immunohistochemistry in eyes and regional cervical lymph nodes (LNs).
Twenty-four hours after intravitreal injection of VIP-Lip, VIP concentration in ocular fluids was 15 times higher than after saline/VIP injection. At that time, EIU clinical severity, ocular infiltrating polymorphonuclear leukocytes (PMNs), and, to a lesser extent, ED1(+) macrophages, as well as inflammatory cytokine and chemokine mRNA expression, were significantly reduced in VIP-Lip-injected rats compared with rats injected with saline/VIP, unloaded liposomes, or saline. Rh-Lip was distributed in vitreous, ciliary body, conjunctiva, retina, and sclera. It was internalized by macrophages and PMNs, and VIP colocalized with liposomes at least up to 14 days after injection. In cervical LNs, resident macrophages internalized VIP-Rh-Lip, and some adjacent lymphocytes showed VIP expression.
VIP was efficient at reducing EIU only when formulated in liposomes, which enhanced its immunosuppressive effect and controlled its delivery to all tissues affected by or involved in ocular inflammation.