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S.A. McClellan, C. Goshgarian, R.P. Barrett, L.D. Hazlett; Characterization of PMN and Macrophages in Innate Immunity to P. aeruginosa . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1445.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the source of iNOS in susceptible C57Bl/6 (B6) vs. resistant BALB/c mice after P. aeruginosa ocular infection and to characterize in vitro PMN and macrophage (Mϕ) cytokine production. Methods: iNOS in PMN and Mϕ was detected in corneas at 1-5 days p.i. by dual-label immunostaining with antibodies against PMN/GR-1, Mϕ/F4/80, and iNOS. Cells were isolated from blood and incubated in vitro with the bacteria. Supernatants were analyzed by ELISA for levels of IL-1ß, MIP–2 and MIP–1α. Results: Mϕ were the predominant source of iNOS in both mouse strains. At 1 day p.i., there was no difference between the two mouse groups in F480+ Mϕ or dual-labeled cells. At 3 days p.i., the number of Mϕ (single and dual-labeled) in BALB/c mice was greater, but by 5 days p.i., both single and dual- labeled cells had decreased in BALB/c mice. GR-1+ PMN and dual-labeled cells were greater in BALB/c at 1 day p.i., but by 3 days p.i., B6 mice had more GR-1+ PMN and at 5 days p.i., more GR-1+ and dual-labeled cells were present in B6 cornea. In vitro, blood PMN and Mϕ from the two groups were incubated with bacteria and cytokines measured in culture supernatants. For PMN, similar levels of IL-1ß were detected at 4 h of culture in both mouse groups. MIP-2 and MIP-1α proteins were higher in BALB/c PMN at both 2 and 4 h. In Mϕ, more IL-1ß was detected at 4 h in BALB/c vs. B6 mice. Mϕ from BALB/c mice secreted more MIP-2 at 2 and 4 h. In contrast, Mϕ from B6 mice had greater MIP-1α protein levels at 4 h. No cytokines/chemokines were detected in culture supernatants at 0 h [or in cell lysates (0-4 h)] and all differences were significant at p<0.05. Conclusions: Mϕ are the major source of iNOS in B6 and BALB/c mice after P. aeruginosa ocular infection. When cells from the two mouse strain were tested in vitro, PMN and Mϕ disparately upregulated pro-inflammatory cytokines/chemokines early in response to the bacteria. Whether the latter occurs in vivo has not been directly tested, but if so, could contribute to the disparate response to infection in the two mouse strains.
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