Escheriehia coil lipopolysaeeharide-induced endophthalmitis and cytokine expression

Abstract

Objective To observe the histopathologic features and expression patterns of tumor necrosis factor-α (TNF-α), interleukin-1β(IL-1β) and Escherichia coli lipopolysaccharide (LPS) in the rat vitreous with LPS induced-endophthalmitis. Methods Wistar rats were randomly divided into saline control group (SC, 136 rats),endophthalmitis group (EO, 168 rats)and blank control group (BC, 12 rats). EO group received an intravitreal injection of 5βl LPS; SC group received 5μl sterile saline and no intervention for BC group. Six, 12, 24, 48, and 72 hours, 5 and 7 days after injection, intraocular inflammation were observed and the eyes and vitreous were collected for histopathological examination and measurement of TNF-α, IL-1β and LPS expression. Results Severe inflammatory responses in the eyes were observed in EO group between six and 72 hours after LPS injection, ocular inflammation subsided seven days after LPS injection. In the vitreous, a peak neutrophil count was observed at 24 hours (1224. 64±132.2) cells/eye that rapidly declined at 72 hours (342. 25± 47. 7) cells/eye. The levels of TNF-α and IL-1β in EO group were peaked at 24 hours with (996.18±89.45) and(5556±1440) pg/L, respectively;Persisted at 48 hours and began to decline rapidly thereafter. Seven days after LPS injection, levels of TNF-α and IL-1β returned to baseline with (22.16 ±5.84) and (73.7±18. 7) pg/L, respectively. LPS concentration in EO group decrease rapidly at 72 hours with (11.03±3.41) ng and disappear on days 7 with (0.22±0.08) ng after LPS injection. Conclusions Massive neutrophils infiltration, high levels expression of TNF-α and IL-1β and spontaneous elimination of bacterial elements in vitreous cavity were major pathologic characteristics in this experimental model. The expression patterns of TNF-α, IL-1β were in accord with LPS clearance process. Key words: Endotoxins; Endophthalmitis/pathotogy; Interleukin-1beta; Tumor necrosis factoralpha; Endotoxins; Animal experimentation