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Expression of toll-like receptor 4 in uvea-resident tissue macrophages during endotoxin-induced uveitis.

Chen W, Hu X, Zhao L, Li S, Lu H - Mol. Vis. (2009)

Bottom Line: During the inflammatory response phase (0-48 h after injection), the proportion of CD163+ tissue macrophages having a round morphology increased (p<0.001 by one-way ANOVA) concurrently with a decrease in the proportion of dendritiform CD163+ cells.The results of the present study indicate that TLR4 expression increased in the iris and iris tissue macrophages expressed TLR4 during EIU.This has significant implications for the understanding of ocular inflammation and for interpreting the potential role of Gram-negative bacteria in the pathogenesis of acute anterior uveitis.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.

ABSTRACT

Purpose: To investigate the dynamics and distribution of toll-like receptor 4 (TLR4)-positive cells and resident tissue macrophages in the uvea during endotoxin-induced uveitis (EIU) in Wistar rats.

Methods: Wistar rats (n=40) received a footpad injection of 200 microg of Vibrio cholera lipopolysaccharide (LPS), and the intensity of anterior segment inflammation was evaluated after the LPS injection. Ten rats each were killed 6, 12, 24 and 48 h after injection. Ten normal Wistar rats were killed as controls (0 h). The iris-ciliary body complex and choroids from each eye were removed and subdivided into segments. Immunohistochemical localization of TLR4 and a resident tissue macrophage marker, cluster of differentiation 163 (CD163), was performed on whole mount isolated iris-ciliary body complexes and choroids. TLR4+ and CD163+ cells in the iris were manually counted, and the cell density (cells/mm(2)) was calculated. The distribution patterns and phenotypes of cells expressing these two proteins were further characterized by double-labeled immunofluorescence studies.

Results: The iris-ciliary body complex did not express TLR4 in normal rats. TLR4+ cells were detectable in the iris stroma 6 h after injection, and the number significantly increased (p<0.001 by one-way ANOVA) 12, 24, and 48 h after injection. The morphology of TLR4+ cells hardly changed 12-48 h after injection. CD163 was expressed in the uvea in all rats. During the inflammatory response phase (0-48 h after injection), the proportion of CD163+ tissue macrophages having a round morphology increased (p<0.001 by one-way ANOVA) concurrently with a decrease in the proportion of dendritiform CD163+ cells. These changes occurred mainly in the macrophages located in the stroma bordering the iris endothelial layer. Double-labeling immunofluorescence demonstrated the co-expression of TLR4 and CD163 in round stroma cells with TLR4 located at the cell membrane and CD163 in the cytoplasm. TLR4+ cells could not be detected in choroids in any of the rats.

Conclusions: The results of the present study indicate that TLR4 expression increased in the iris and iris tissue macrophages expressed TLR4 during EIU. This has significant implications for the understanding of ocular inflammation and for interpreting the potential role of Gram-negative bacteria in the pathogenesis of acute anterior uveitis.

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Related in: MedlinePlus

CD163+ cells displayed different morphologies at different layers in the iris 48 h after LPS injection. This figure shows different stromal layers from the epithelial to endothelial (from A to F) in the same field. Dendritiform cells are located in the stroma adjacent to the epithelial layer (A) while round-pleiomorphic cells are adjacent to the endothelial layer (F). The cells that arrows and arrowheads point to represent the same cells, respectively. Original magnification: A–F 400X.
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f5: CD163+ cells displayed different morphologies at different layers in the iris 48 h after LPS injection. This figure shows different stromal layers from the epithelial to endothelial (from A to F) in the same field. Dendritiform cells are located in the stroma adjacent to the epithelial layer (A) while round-pleiomorphic cells are adjacent to the endothelial layer (F). The cells that arrows and arrowheads point to represent the same cells, respectively. Original magnification: A–F 400X.

Mentions: The rat CD163 antigen has been identified as an ectodermal dysplasia 2 (ED2) antigen [20], and monoclonal antibody ED2 is a well recognized anti-rat tissue macrophage marker. The network of CD163+ tissue macrophages in the current study was predominantly of dendritiform appearance during the first 6 h after LPS injection (Figure 4A,B). At 12 h, the morphology of the positive cells in the iris was markedly changed. The cells possessed fewer dendritic processes, and the proportion of round-ovoid cells was increased (Figure 4C–E). The percentage of cells with round-pleiomorphic appearance increased from 13% in the control rats before injection to approximately 80% of the cell population 12–48 h after injection (p<0.001; Figure 2D). The changes occurred mainly in the macrophages located in the stroma near the iris endothelial layer (Figure 5A–F). During the EIU inflammatory process, there was little change in the total density of CD163+ cells (Figure 2C). However, 48 h after injection, small, round, distinctive positive cells were observed (Figure 4E).


Expression of toll-like receptor 4 in uvea-resident tissue macrophages during endotoxin-induced uveitis.

Chen W, Hu X, Zhao L, Li S, Lu H - Mol. Vis. (2009)

CD163+ cells displayed different morphologies at different layers in the iris 48 h after LPS injection. This figure shows different stromal layers from the epithelial to endothelial (from A to F) in the same field. Dendritiform cells are located in the stroma adjacent to the epithelial layer (A) while round-pleiomorphic cells are adjacent to the endothelial layer (F). The cells that arrows and arrowheads point to represent the same cells, respectively. Original magnification: A–F 400X.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2664840&req=5

f5: CD163+ cells displayed different morphologies at different layers in the iris 48 h after LPS injection. This figure shows different stromal layers from the epithelial to endothelial (from A to F) in the same field. Dendritiform cells are located in the stroma adjacent to the epithelial layer (A) while round-pleiomorphic cells are adjacent to the endothelial layer (F). The cells that arrows and arrowheads point to represent the same cells, respectively. Original magnification: A–F 400X.
Mentions: The rat CD163 antigen has been identified as an ectodermal dysplasia 2 (ED2) antigen [20], and monoclonal antibody ED2 is a well recognized anti-rat tissue macrophage marker. The network of CD163+ tissue macrophages in the current study was predominantly of dendritiform appearance during the first 6 h after LPS injection (Figure 4A,B). At 12 h, the morphology of the positive cells in the iris was markedly changed. The cells possessed fewer dendritic processes, and the proportion of round-ovoid cells was increased (Figure 4C–E). The percentage of cells with round-pleiomorphic appearance increased from 13% in the control rats before injection to approximately 80% of the cell population 12–48 h after injection (p<0.001; Figure 2D). The changes occurred mainly in the macrophages located in the stroma near the iris endothelial layer (Figure 5A–F). During the EIU inflammatory process, there was little change in the total density of CD163+ cells (Figure 2C). However, 48 h after injection, small, round, distinctive positive cells were observed (Figure 4E).

Bottom Line: During the inflammatory response phase (0-48 h after injection), the proportion of CD163+ tissue macrophages having a round morphology increased (p<0.001 by one-way ANOVA) concurrently with a decrease in the proportion of dendritiform CD163+ cells.The results of the present study indicate that TLR4 expression increased in the iris and iris tissue macrophages expressed TLR4 during EIU.This has significant implications for the understanding of ocular inflammation and for interpreting the potential role of Gram-negative bacteria in the pathogenesis of acute anterior uveitis.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.

ABSTRACT

Purpose: To investigate the dynamics and distribution of toll-like receptor 4 (TLR4)-positive cells and resident tissue macrophages in the uvea during endotoxin-induced uveitis (EIU) in Wistar rats.

Methods: Wistar rats (n=40) received a footpad injection of 200 microg of Vibrio cholera lipopolysaccharide (LPS), and the intensity of anterior segment inflammation was evaluated after the LPS injection. Ten rats each were killed 6, 12, 24 and 48 h after injection. Ten normal Wistar rats were killed as controls (0 h). The iris-ciliary body complex and choroids from each eye were removed and subdivided into segments. Immunohistochemical localization of TLR4 and a resident tissue macrophage marker, cluster of differentiation 163 (CD163), was performed on whole mount isolated iris-ciliary body complexes and choroids. TLR4+ and CD163+ cells in the iris were manually counted, and the cell density (cells/mm(2)) was calculated. The distribution patterns and phenotypes of cells expressing these two proteins were further characterized by double-labeled immunofluorescence studies.

Results: The iris-ciliary body complex did not express TLR4 in normal rats. TLR4+ cells were detectable in the iris stroma 6 h after injection, and the number significantly increased (p<0.001 by one-way ANOVA) 12, 24, and 48 h after injection. The morphology of TLR4+ cells hardly changed 12-48 h after injection. CD163 was expressed in the uvea in all rats. During the inflammatory response phase (0-48 h after injection), the proportion of CD163+ tissue macrophages having a round morphology increased (p<0.001 by one-way ANOVA) concurrently with a decrease in the proportion of dendritiform CD163+ cells. These changes occurred mainly in the macrophages located in the stroma bordering the iris endothelial layer. Double-labeling immunofluorescence demonstrated the co-expression of TLR4 and CD163 in round stroma cells with TLR4 located at the cell membrane and CD163 in the cytoplasm. TLR4+ cells could not be detected in choroids in any of the rats.

Conclusions: The results of the present study indicate that TLR4 expression increased in the iris and iris tissue macrophages expressed TLR4 during EIU. This has significant implications for the understanding of ocular inflammation and for interpreting the potential role of Gram-negative bacteria in the pathogenesis of acute anterior uveitis.

Show MeSH
Related in: MedlinePlus