Prevention of Endotoxin-Induced Uveitis in Rats by Plant Sterol Guggulsterone

Abstract

PURPOSE To investigate the anti-inflammatory effects of guggulsterone, an antioxidant and anti-tumor agent, in endotoxin-induced uveitis (EIU) in rats and to elucidate the underlying molecular mechanism(s) related to ocular inflammation. METHODS EIU was induced by subcutaneous injection of lipopolysaccharide (LPS) (150 ug) in Lewis rats treated with guggulsterone (30 mg/kg body wt, i.p) or its carrier. After 24 h the rats were sacrificed, eyes were enucleated and aqueous humors (AqH) were collected. The number of infiltrating cells, levels of metrix metalloproteinase-2 (MMP-2), nitric oxide (NO), and prostaglandin E2 (PGE2) were determined in AqH by specific ELISAs. An antibody array was used to measure the expression of various inflammatory cytokines in AqH. The expression of MMP-2, iNOS, Cox-2, phospho-IκB and phospho-NF-κB were determined immunohistochemically. Human primary non-pigment ciliary epithelial cells (HNPECs) were used to determine the in vitro efficacy of guggulsterone on LPS-induced inflammatory response. RESULTS Compared to control, the EIU rat eye AqH had significantly higher number of infiltrating cells, total protein, and inflammatory markers such as MMP-2, NO, and PGE2 and treatment of guggulsterone prevented EIU-induced increases. Further, guggulsterone also prevented the expression of MMP-2, iNOS, and Cox-2 proteins as well as IκB and NF-κB in various eye tissues. Moreover, in cultured HNPECs guggulsterone inhibited LPS-induced expression of inflammatory proteins. CONCLUSIONS Our results for the first time demonstrate that the plant sterol guggulsterone suppresses the ocular inflammation in EIU suggesting that supplementation of guggulsterone could be a novel approach for the treatment of ocular inflammation.

Antidiabetic Drug Metformin Suppresses Endotoxin-Induced Uveitis in Rats

“…8 However, prescription-based use of many of these agents, such as guggulsterone, 60 ethyl pyruvate, 61 lutein, 62 and astazanthin, 63 in humans for the treatment of uveitis has not materialized for various reasons. Prominent reasons that limit their use in humans are lack of toxicity studies, lack of knowledge on safe dosage range, potential toxicity on higher therapeutic dosage, and lack of studies to determine safe delivery methods.…”

Anti-Inflammatory Effect of the Proteasome Inhibitor Bortezomib on Endotoxin-Induced Uveitis in Rats

“…[7][8][9][10][11][12] Proteasomal degradation of the inhibitory factor IjB is necessary for NF-jB activation, and the inhibition of proteasome function theoretically maintains NF-jB in the inactive state in the cytosol and prevents its nuclear translocation. Proteasome inhibition is effective in treating several animal models of autoimmune disease, and to our knowledge our study is the first to demonstrate its antiinflammatory effect in EIU.…”

“…Several experimental studies have noted that there is increased expression of activated NF-jB associated with EIU, and that the inhibition of NF-jB can halt inflammation. [7][8][9][10][11][12] NFjB is an ubiquitous transcription factor, and it regulates the transcription of a wide range of genes responsible for inflammation, such as cytokines, chemokines, cell-adhesion molecules, and stress-response proteins. 13 Several inflammatory mediators, including interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-a, interferon (IFN)-c, monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS), and cyclo-oxygenase (COX)-2, are increased in animals with EIU and seem to be up-regulated by NF-jB.…”

“…13 Several inflammatory mediators, including interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-a, interferon (IFN)-c, monocyte chemoattractant protein (MCP)-1, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS), and cyclo-oxygenase (COX)-2, are increased in animals with EIU and seem to be up-regulated by NF-jB. [7][8][9][10]12,[14][15][16][17] The ubiquitin-proteasome system is the major nonlysosomal system for intracellular protein degradation and is crucial in maintaining basic cellular functions, such as cell cycle progression and apoptosis. This system also is involved in many pathologic conditions, including cancer, ischemiareperfusion injury, autoimmune disease, inflammation, and allograft rejection.…”

Herbal Drugs for Ophthalmic Use

“…This study reported that hot water extract of Scutellariae radix may have an inhibitory effect on experimental anterior uveitis induced by lipopolysaccharide (LPS) in pigmented rabbits. Berberine from Berberis aristata ( daaru haridra in Ayurveda), plant sterol guggulsterone, polyphenols from Lonicera caerulea L. and Aronia extract, anthocyanins from Vaccinium myrtillus L., and Gingko biloba have exhibited potent anti-infl ammatory activity against endotoxin-induced uveitis in vivo (Kalariya et al 2010 ;Jin et al 2006 ;Ohgami et al 2005 ;Yao et al 2010 ). Plant pigments such as, fucoxanthin, lutein, and Lycium have been reported to show protection against LPS-induced uveitis; however further investigations elucidating the working mechanism are anticipated.…”