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Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

Sahu RP, Rezania S, Ocana JA, DaSilva-Arnold SC, Bradish JR, Richey JD, Warren SJ, Rashid B, Travers JB, Konger RL - PLoS ONE (2014)

Bottom Line: Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications.Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis.These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

View Article: PubMed Central - PubMed

Affiliation: Departments of Pathology & Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America.

ABSTRACT
Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased chronic inflammation in response to phorbol ester application. In this present study, we demonstrate that topical application of the non-hydrolysable PAF mimetic (carbamoyl-PAF (CPAF)), exerts a potent, dose-dependent, and short-lived edema response in WT mice, but not Ptafr -/- mice or mice deficient in c-Kit (c-KitW-sh/W-sh mice). Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications. Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis. The ability of CPAF to suppress acute and chronic inflammatory changes in response to PMA application(s) was PAF-R dependent, as CPAF had no effect on basal or PMA-induced inflammation in Ptafr-/- mice. Moreover, c-Kit appears to be necessary for the anti-inflammatory effects of CPAF, as CPAF had no observable effect in c-KitW-sh/W-sh mice. These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

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Dose and time related acute ear inflammation changes in response to topical CPAF.1A. Topical CPAF dose-dependently induces rapid inflammatory responses as measured by ear thickness measurements. One ear of WT and Ptafr (-/-) were treated with one of three doses of CPAF (20 µl of a 0.1, 0.3, and 1.0 mM solution for a total treatment dose of 2, 6, or 20 nmole CPAF per ear). The contralateral ear was treated with acetone alone (VEH). Ear thickness was measured prior to treatment and 2 hours after treatment. After the pretreatment ear thickness values were subtracted, the mean and SEM were plotted (n = 4 for 20 nmole and n = 8 for 2 & 6 nmole CPAF & VEH treated mouse ears). 1B. Topical CPAF treatment induces a rapid, but transient increase in inflammation as measured by ear thickness changes. One ear of wildtype (WT) and Ptafr (-/-) mice was treated with 20 µl of CPAF (20 nmoles of a 0.1 mM solution in acetone) and 20 µl of acetone (VEH) was applied to the contralateral ear. Ear thickness was measured just prior to reagent application and at 1, 2, 4, and 8 hours after application. Results represent the mean and SEM (n = 4 mice) after subtracting the pretreatment ear thickness. CPAF induced a significant increase in ear thickness in WT mice relative to the WT+VEH treated ears. *, p<0.05; **, p<0.01; ***; p<0.001; 2-tailed t-test.
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pone-0111608-g001: Dose and time related acute ear inflammation changes in response to topical CPAF.1A. Topical CPAF dose-dependently induces rapid inflammatory responses as measured by ear thickness measurements. One ear of WT and Ptafr (-/-) were treated with one of three doses of CPAF (20 µl of a 0.1, 0.3, and 1.0 mM solution for a total treatment dose of 2, 6, or 20 nmole CPAF per ear). The contralateral ear was treated with acetone alone (VEH). Ear thickness was measured prior to treatment and 2 hours after treatment. After the pretreatment ear thickness values were subtracted, the mean and SEM were plotted (n = 4 for 20 nmole and n = 8 for 2 & 6 nmole CPAF & VEH treated mouse ears). 1B. Topical CPAF treatment induces a rapid, but transient increase in inflammation as measured by ear thickness changes. One ear of wildtype (WT) and Ptafr (-/-) mice was treated with 20 µl of CPAF (20 nmoles of a 0.1 mM solution in acetone) and 20 µl of acetone (VEH) was applied to the contralateral ear. Ear thickness was measured just prior to reagent application and at 1, 2, 4, and 8 hours after application. Results represent the mean and SEM (n = 4 mice) after subtracting the pretreatment ear thickness. CPAF induced a significant increase in ear thickness in WT mice relative to the WT+VEH treated ears. *, p<0.05; **, p<0.01; ***; p<0.001; 2-tailed t-test.

Mentions: In a previous study [7] and in Fig 1A, we show that a single topical application of increasing doses of the non-hydrolyzable PAF-R agonist, CPAF, results in a dose-dependent increase in ear thickness at two hours after application. In Fig 1B, a time course study demonstrates that CPAF-induced ear thickness changes occur rapidly, with significant increases in ear thickness noted by 1 hour after application and peak ear thickness was noted at 2 hrs. Importantly, following a single application of CPAF the changes in ear thickness were transient and declined to near baseline by 8 hours after application. The rapid and transient nature of the response strongly suggests that changes in vascular permeability leading to edema formation are largely responsible for the changes in ear thickness. This is consistent with the well-known ability of PAF to induce vasodilation and vascular permeability [37]. To rule out PAF-R independent effects [38], mice with germline loss of the Ptafr gene (Ptafr-/- mice) were also treated with CPAF. At all doses studied, topical CPAF application failed to elicit an inflammatory reaction in Ptafr-/- mice (Figs 1A&B), verifying the specificity of the pharmacological effect.


Topical application of a platelet activating factor receptor agonist suppresses phorbol ester-induced acute and chronic inflammation and has cancer chemopreventive activity in mouse skin.

Sahu RP, Rezania S, Ocana JA, DaSilva-Arnold SC, Bradish JR, Richey JD, Warren SJ, Rashid B, Travers JB, Konger RL - PLoS ONE (2014)

Dose and time related acute ear inflammation changes in response to topical CPAF.1A. Topical CPAF dose-dependently induces rapid inflammatory responses as measured by ear thickness measurements. One ear of WT and Ptafr (-/-) were treated with one of three doses of CPAF (20 µl of a 0.1, 0.3, and 1.0 mM solution for a total treatment dose of 2, 6, or 20 nmole CPAF per ear). The contralateral ear was treated with acetone alone (VEH). Ear thickness was measured prior to treatment and 2 hours after treatment. After the pretreatment ear thickness values were subtracted, the mean and SEM were plotted (n = 4 for 20 nmole and n = 8 for 2 & 6 nmole CPAF & VEH treated mouse ears). 1B. Topical CPAF treatment induces a rapid, but transient increase in inflammation as measured by ear thickness changes. One ear of wildtype (WT) and Ptafr (-/-) mice was treated with 20 µl of CPAF (20 nmoles of a 0.1 mM solution in acetone) and 20 µl of acetone (VEH) was applied to the contralateral ear. Ear thickness was measured just prior to reagent application and at 1, 2, 4, and 8 hours after application. Results represent the mean and SEM (n = 4 mice) after subtracting the pretreatment ear thickness. CPAF induced a significant increase in ear thickness in WT mice relative to the WT+VEH treated ears. *, p<0.05; **, p<0.01; ***; p<0.001; 2-tailed t-test.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222871&req=5

pone-0111608-g001: Dose and time related acute ear inflammation changes in response to topical CPAF.1A. Topical CPAF dose-dependently induces rapid inflammatory responses as measured by ear thickness measurements. One ear of WT and Ptafr (-/-) were treated with one of three doses of CPAF (20 µl of a 0.1, 0.3, and 1.0 mM solution for a total treatment dose of 2, 6, or 20 nmole CPAF per ear). The contralateral ear was treated with acetone alone (VEH). Ear thickness was measured prior to treatment and 2 hours after treatment. After the pretreatment ear thickness values were subtracted, the mean and SEM were plotted (n = 4 for 20 nmole and n = 8 for 2 & 6 nmole CPAF & VEH treated mouse ears). 1B. Topical CPAF treatment induces a rapid, but transient increase in inflammation as measured by ear thickness changes. One ear of wildtype (WT) and Ptafr (-/-) mice was treated with 20 µl of CPAF (20 nmoles of a 0.1 mM solution in acetone) and 20 µl of acetone (VEH) was applied to the contralateral ear. Ear thickness was measured just prior to reagent application and at 1, 2, 4, and 8 hours after application. Results represent the mean and SEM (n = 4 mice) after subtracting the pretreatment ear thickness. CPAF induced a significant increase in ear thickness in WT mice relative to the WT+VEH treated ears. *, p<0.05; **, p<0.01; ***; p<0.001; 2-tailed t-test.
Mentions: In a previous study [7] and in Fig 1A, we show that a single topical application of increasing doses of the non-hydrolyzable PAF-R agonist, CPAF, results in a dose-dependent increase in ear thickness at two hours after application. In Fig 1B, a time course study demonstrates that CPAF-induced ear thickness changes occur rapidly, with significant increases in ear thickness noted by 1 hour after application and peak ear thickness was noted at 2 hrs. Importantly, following a single application of CPAF the changes in ear thickness were transient and declined to near baseline by 8 hours after application. The rapid and transient nature of the response strongly suggests that changes in vascular permeability leading to edema formation are largely responsible for the changes in ear thickness. This is consistent with the well-known ability of PAF to induce vasodilation and vascular permeability [37]. To rule out PAF-R independent effects [38], mice with germline loss of the Ptafr gene (Ptafr-/- mice) were also treated with CPAF. At all doses studied, topical CPAF application failed to elicit an inflammatory reaction in Ptafr-/- mice (Figs 1A&B), verifying the specificity of the pharmacological effect.

Bottom Line: Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications.Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis.These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

View Article: PubMed Central - PubMed

Affiliation: Departments of Pathology & Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America.

ABSTRACT
Platelet activating factor (PAF) has long been associated with acute edema and inflammatory responses. PAF acts by binding to a specific G-protein coupled receptor (PAF-R, Ptafr). However, the role of chronic PAF-R activation on sustained inflammatory responses has been largely ignored. We recently demonstrated that mice lacking the PAF-R (Ptafr-/- mice) exhibit increased cutaneous tumorigenesis in response to a two-stage chemical carcinogenesis protocol. Ptafr-/- mice also exhibited increased chronic inflammation in response to phorbol ester application. In this present study, we demonstrate that topical application of the non-hydrolysable PAF mimetic (carbamoyl-PAF (CPAF)), exerts a potent, dose-dependent, and short-lived edema response in WT mice, but not Ptafr -/- mice or mice deficient in c-Kit (c-KitW-sh/W-sh mice). Using an ear inflammation model, co-administration of topical CPAF treatment resulted in a paradoxical decrease in both acute ear thickness changes associated with a single PMA application, as well as the sustained inflammation associated with chronic repetitive PMA applications. Moreover, mice treated topically with CPAF also exhibited a significant reduction in chemical carcinogenesis. The ability of CPAF to suppress acute and chronic inflammatory changes in response to PMA application(s) was PAF-R dependent, as CPAF had no effect on basal or PMA-induced inflammation in Ptafr-/- mice. Moreover, c-Kit appears to be necessary for the anti-inflammatory effects of CPAF, as CPAF had no observable effect in c-KitW-sh/W-sh mice. These data provide additional evidence that PAF-R activation exerts complex immunomodulatory effects in a model of chronic inflammation that is relevant to neoplastic development.

Show MeSH
Related in: MedlinePlus