Topicai Administration Of Diminazene Aceturate Decreases Inflammation Of Endotoxin-Induced Uveitis

Purpose:Our previous study demonstrated that intraperitoneal injection of Diminazene Aceturate (DIZE) attenuated uveitis by activating ocular angiotensin-converting enzyme 2 (ACE2). Here we investigated the anti-inflammatory effects on the ocular anterior segment by topical administration of DIZE solution and to explore the downstream target molecules involved in the anti-inflammatory mechanism after ACE2 activation.Methods:Endotoxin-induced uveitis (EIU) in rats was induced by subcutaneous injection of lipopolysaccharides (LPS,200μg) in 0.1 ml of sterile saline. DIZE (0.025,0.05 or 0.1%) and dexamethasone (0.1%) solutions applied topically (10 μl eyedrops) to both eyes every two hours for 6 times before and after LPS injection. The inflammation of the ocular anterior segment was observed and the clinical scores were evaluated at 24 h after LPS injection. The total protein concentration and levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) in aqueous humor were determined.CD11b positive cells in the iris ciliary body (ICB) were stained by immunohistochemistry. The mRNA levels of inflammatory cytokines and mediators including IL-1β,TNF-α, COX-2 and iNOS or NF-κB subunit p65 in ICB were analyzed by real time RT-PCR. The protein expression of NF-κB p65 and phosphorylated protein of p38 MAPK was detected by Western blotting.Results:Topical administration of DIZE decreased clinical scores and the total protein concentration as well as TNF-α and IL-6 levels in the aqueous humor. Meanwhile, the mRNA levels of inflammatory cytokines and mediators including IL-1β, TNF-α, COX-2 and iNOS in ICB were down-regulated. DIZE reduced recruitment of CD11b positive cells adajcent to the ICB. Furthermore, DIZE down-regulated the expressions of NF-κB subunit p65 at protein and mRNA levels, and inhibited phosphorylation of p38 MAPK protein in ICB.Conclusions:Topical administration of DIZE suppressed ocular inflammation in EIU and decreased the levels of inflammatory cytokines. DIZE attenuated the activation of NF-κB and p38 MAPK in EIU, which may be associated with ACE2 mediated anti-inflammatory effects. Our data provided further evidence that DIZE may represent a novel class of drug for the management of ocular inflammation.