Purpose: To investigate the roles of activation of macrophages isolated from C3H/HeN and C3H/HeJ mice and stimulated by lipopolysaccharide (LPS), and toll-like receptor 4-mediated signal transduction in the development of acute anterior uveitis.
Methods: Establish animal models with acute anterior uveitis by intraperitoneal injection of vibrio cholera endotoxin into C3H/HeN mice (wild type) and C3H/HeJ mice (toll-like receptor 4 (TLR4) gene defection type). Peritoneal macrophages were obtained from C3H/HeN and C3H/HeJ mice. Immunofluorescence staining was used to identify the F4/80+ positive cells (iris, peritoneal macrophages) and to observe the expression of TLR4, myeloid differentiation factor 88 (MyD88), and nuclear factor kappa B (NF-κB), with or without LPS (1 μg/ml). To investigate the importance of TLR4 in the signal pathway, a group, blocked by anti-TLR4 antibody before LPS stimulation, was added to theC3H/HeN mice sample.
Results: In vitro, in C3H/HeN mice, Iris posterior synechia was found 24 h later. However, an inflammation reaction was not found in the anterior chamber of the C3H/HeJ mice. In cell culture, TLR4 expression was observed in peritoneal macrophages of the C3H/HeN mice, both with and without LPS stimulation. TLR4 was primarily expressed in the membrane and no significant difference in inflorescence intensity (p=0.081) was found among the groups. MyD88 was expressed in the cytoplasm and the nucleus. There is statistical significance in the fluorescence intensity among groups of C3H/HeN mice (p<0.0001). NF-κB was primarily expressed in the cytoplasm before LPS stimulation. However, this occurred 1 h after LPS stimulation and could be observed in the nucleus. Three hours after LPS stimulation, the expression of NF-κB could not be detected in the cytoplasm or the nucleus. The fluorescence intensity of TLR4 and MyD88 expression showed no significant difference (p=0.113) between the anti-TLR4 antibody pretreatment group and the other groups of C3H/HeN mice. However, in the anti-TLR4 antibody pretreatment group, 1 h to 24 h after LPS stimulation, NF-κB only expressed in the cell membrane. Peritoneal macrophages from all groups of C3H/HeJ mice showed no obvious changes in morphology and size after LPS stimulation (p=0.257). TLR4 was primarily expressed in the cell membrane, and fluorescence intensity showed no statistical significance (p=0.228); MyD88 was expressed in the cytoplasm and the nucleus and there was no significant difference in fluorescence intensity among the groups (p=0.108); NF- κB was expressed in the cytoplasm, without LPS stimulation; however, 1 h after LPS stimulation, it appeared in the cell membrane and persisted until 24 h.
Conclusions: Acute anterior uveitis can be induced in wild-type mice, but it cannot be induced in TLR4 gene-deficient mice. The variation of expression of TLR4, and its downstream signal transduction molecules, MyD88 and NF-κB, after LPS stimulation in vitro, suppose the potential role of a TLR4-MyD88-dependent pathway in the pathogenesis of acute anterior uveitis. The blockage of this pathway by anti-TLR4 may signal a new direction in the treatment of acute anterior uveitis.