Inhibition of endotoxin-induced uveitis and potentiation of cyclooxygenase-2 protein expression by alpha-melanocyte-stimulating hormone.

PURPOSE: The efficacy of alpha-melanocyte-stimulating hormone (alpha-MSH) on endotoxin-induced uveitis (EIU) was investigated in rats. Several studies have demonstrated that there are various inflammatory reactions mediated by an alpha-MSH receptor in macrophages. In addition, as it is known that cyclooxygenase (COX)-2 is induced by a variety of stimuli and plays an important role in inflammation, COX-2 expression was also investigated in macrophage cells treated with alpha-MSH in vitro to clarify its anti-inflammatory effect. METHODS: EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). The number of infiltrating cells and protein concentration in the aqueous humor collected 24 hours after the LPS treatment was determined. The levels of prostaglandin (PG)-E2, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 production were determined. RAW 264.7 cells were pretreated with various concentrations of alpha-MSH for 24 hours and subsequently incubated with 10 microg/mL LPS for 24 hours. COX-2 protein expression was analyzed by Western blot analysis. RESULTS: alpha-MSH suppressed the development of EIU in a dose-dependent fashion. The treatment with alpha-MSH reduced the PGE2, TNF-alpha, IL-6, and MCP-1 concentrations in aqueous humor. The COX-2 protein expression in the alpha-MSH group decreased. CONCLUSIONS: This study suggests that alpha-MSH has an antiocular inflammatory effect, by suppression of PGE2, TNF-alpha, IL-6, and MCP-1 production and blocking of COX-2 expression.

Effect of human cationic antimicrobial protein 18 Peptide on endotoxin-induced uveitis in rats.

PURPOSE: Human cationic antimicrobial protein 18 (hCAP18, 18 kDa) was originally identified in leukocytes on the basis of its antimicrobial activity. The peptide composed of the 27 C-terminal amino acids of hCAP18 (hCAP18(109-135)) binds lipopolysaccharide (LPS). The purpose of the present study was to investigate the effects of hCAP18 peptide on endotoxin-induced uveitis (EIU) in rats. METHODS: EIU was induced by footpad injection of LPS. Each rat was injected intravenously with 1, 10, or 100 micro g hCAP18 peptide in 0.1 mL of PBS immediately after LPS injection in male Lewis rats. At 24 hours after LPS injection, enzyme-linked immunosorbent assay was performed to evaluate concentrations of protein, nitric oxide (NO), tumor necrosis factor (TNF)-alpha, prostaglandin (PG)-E2, interleukin (IL)-6, monocyte chemoattractant protein (MCP)-1 and macrophage inflammatory protein (MIP)-2 in aqueous humor. Also, EIU was evaluated by counting inflammatory cells in aqueous humor. RESULTS: hCAP18 peptide at 10 and 100 micro g significantly suppressed an LPS-induced increase in the number of inflammatory cells and the levels of protein, NO, TNF-alpha, PGE2, MCP-1, and MIP-2. The anti-inflammatory effect of 10 micro g hCAP18 peptide was as strong as that of 100 micro g hCAP18 peptide. Treatment with 1 micro g hCAP18 peptide did not suppress EIU, compared with the LPS group. CONCLUSIONS: The present results indicate that hCAP18 peptide suppresses development of EIU. A possible mechanism for the ocular anti-inflammatory effect of hCAP18 peptide is that it suppresses onset of LPS-triggered inflammatory reactions by binding directly to LPS.

Involvement of p27KIP1 in the proliferation of the developing corneal endothelium.

PURPOSE: To examine the involvement of p27(KIP1) in the regulation of the proliferation of the developing corneal endothelium. METHODS: Central and peripheral corneas in C57Bl6 mice at postnatal day (P)1, P11, and 12 weeks after birth were analyzed by immunocytochemistry with anti-p27(KIP1), -p57(KIP2), and -proliferating cell nuclear antigen (PCNA) antibodies. Nuclear staining was performed with 4',6'-diamino-2-phenylindole (DAPI) in wholemounts of corneal endothelium of the center and peripheral cornea in wild-type and p27(KIP1) knockout (-/-) mice at 12 weeks of age. p27(KIP1-/-) and control mice were injected with bromodeoxyuridine (BrdU) once on P7, twice per day on P8 and P9, and once on P10 and then were analyzed by a BrdU cell-proliferation assay on P11. RESULTS: On P1, p27(KIP1) immunoreactivity was detected in a small number of corneal endothelial cells, and many endothelial cells expressed PCNA. At P11 and 12 weeks after birth, p27(KIP1) immunoreactivity was detected in many corneal endothelial cells. PCNA-positive cells in the endothelium were rare on P11 and completely absent at 12 weeks after birth. p57(KIP2) was not detected in either corneal epithelium or endothelium at P1, P11, or 12 weeks after birth. In wholemounts of corneal endothelium at 12 weeks of age, the number of endothelial nuclei in the p27(KIP1-/-) mice was significantly higher than that in wild-type mice in both the center and peripheral regions of the cornea. In the BrdU assay, positive cells were abundant in the corneal endothelium of p27(KIP1-/-) mice, whereas there were few positive cells in control mice. PCNA immunoreactivity in the endothelium of the p27(KIP1-/-) mice was completely absent at 12 weeks after birth. CONCLUSIONS: These results suggest that p27(KIP1) is involved in the regulation of proliferation in the endothelium of the developing cornea.

Anti-inflammatory effects of alpha-melanocyte-stimulating hormone against rat endotoxin-induced uveitis and the time course of inflammatory agents in aqueous humor.

PURPOSE: We examined the effects of the immunosuppressive neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) on rat endotoxin-induced uveitis, and to measure the expression of inflammatory cytokines and chemokines with and without the alpha-MSH treatment over the course of the disease. METHODS: We injected Lewis rats once with Salmonella typhimurium lipopolysaccharide (LPS) to induce uveitis. The rats were given intravenous injections of 250, 500 or 1000 microg of alpha-MSH. The eyes were examined over the next 24 h for inflammation. Aqueous humor was collected 6, 12 and 24 h after endotoxin injections and the number of infiltrating cells were counted in anterior chamber. In addition, we assayed the concentration of protein, nitric oxide, TNF-alpha, IL-6, MCP-1 and MIP-2. RESULTS: Rats injected with alpha-MSH showed a significant decrease in the number of infiltrating cells in anterior chamber. Moreover, alpha-MSH-treated rats with endotoxin-induced uveitis (EIU) showed significantly lower concentrations of protein, nitric oxide, proinflammatory cytokines and chemokines in their aqueous humor. Even the early stages of EIU were suppressed by the injection of alpha-MSH. CONCLUSIONS: Our results demonstrate that the immunosuppressive neuropeptide alpha-MSH inhibits the early induction events of endotoxin-induced inflammation in the eye; therefore, suppresses the subsequent infiltration of cells and intraocular production of inflammatory cytokines and chemokines in eyes. alpha-MSH has a possibility of being a therapeutic strategy for anterior uveitis.