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Uteroglobin represses allergen-induced inflammatory response by blocking PGD2 receptor-mediated functions.

Mandal AK, Zhang Z, Ray R, Choi MS, Chowdhury B, Pattabiraman N, Mukherjee AB - J. Exp. Med. (2004)

Bottom Line: These effects are abrogated by recombinant UG treatment.Here we report that DP signaling is mediated via p38 mitogen-activated protein kinase, p44/42 mitogen-activated protein kinase, and protein kinase C pathways in a cell type-specific manner leading to nuclear factor-kappaB activation stimulating COX-2 gene expression.Further, we found that recombinant UG blocks DP-mediated nuclear factor-kappaB activation and suppresses COX-2 gene expression.

View Article: PubMed Central - PubMed

Affiliation: Bldg. 10, Rm. 9S241, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.

ABSTRACT
Uteroglobin (UG) is an antiinflammatory protein secreted by the epithelial lining of all organs communicating with the external environment. We reported previously that UG-knockout mice manifest exaggerated inflammatory response to allergen, characterized by increased eotaxin and Th2 cytokine gene expression, and eosinophil infiltration in the lungs. In this study, we uncovered that the airway epithelia of these mice also express high levels of cyclooxygenase (COX)-2, a key enzyme for the production of proinflammatory lipid mediators, and the bronchoalveolar lavage fluid (BALF) contain elevated levels of prostaglandin D2. These effects are abrogated by recombinant UG treatment. Although it has been reported that prostaglandin D2 mediates allergic inflammation via its receptor, DP, neither the molecular mechanism(s) of DP signaling nor the mechanism by which UG suppresses DP-mediated inflammatory response are clearly understood. Here we report that DP signaling is mediated via p38 mitogen-activated protein kinase, p44/42 mitogen-activated protein kinase, and protein kinase C pathways in a cell type-specific manner leading to nuclear factor-kappaB activation stimulating COX-2 gene expression. Further, we found that recombinant UG blocks DP-mediated nuclear factor-kappaB activation and suppresses COX-2 gene expression. We propose that UG is an essential component of a novel innate homeostatic mechanism in the mammalian airways to repress allergen-induced inflammatory responses.

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Molecular mechanism(s) of DP signaling is cell type specific. PGD2 stimulation of BSM-2146 cells induces tyrosine phosphorylation of p38 (A) and p44/42 (B), whereas in NIH-3T3 cells such treatment leads to tyrosine phosphorylation of only p38 MAPK (C). Moreover, p38 MAPK inhibitor, SB203580, inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (D). In BSM-2146 cells, rUG (1 μM) treatment inhibits PGD2-mediated phosphorylation of both p44/42 and p38 MAPK (E), and in NIH-3T3 cells rUG inhibits phosphorylation of only p38 MAPK (F).
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fig4: Molecular mechanism(s) of DP signaling is cell type specific. PGD2 stimulation of BSM-2146 cells induces tyrosine phosphorylation of p38 (A) and p44/42 (B), whereas in NIH-3T3 cells such treatment leads to tyrosine phosphorylation of only p38 MAPK (C). Moreover, p38 MAPK inhibitor, SB203580, inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (D). In BSM-2146 cells, rUG (1 μM) treatment inhibits PGD2-mediated phosphorylation of both p44/42 and p38 MAPK (E), and in NIH-3T3 cells rUG inhibits phosphorylation of only p38 MAPK (F).

Mentions: Although our results demonstrate that PGD2 stimulates COX-2 expression via DP, the molecular mechanisms of DP signaling, until now, remained unclear. Thus, we studied the mechanism(s) of DP signaling using our in vitro experimental system. The prostanoids signal through specific G protein–coupled receptors, and it has been reported that many agonists of these receptors activate the MAPK pathway (28). Thus, we analyzed the phosphorylation-dependent activation of kinase pathways. We treated the cells with PGD2 for varying lengths of time and analyzed tyrosine phosphorylation of MAPK by Western blot analysis using anti–phospho p38-MAPK (Tyr-182) and anti–phospho p44/42-MAPK (Tyr-204) antibodies. PGD2 stimulates the phosphorylation of both p38- (Fig. 4 A) and p44/42-MAPK (Fig. 4 B) in BSM-2146 cells, whereas in NIH-3T3 cells PGD2 stimulates the phosphorylation of p38 (Fig. 4 C) but not p44/42 MAPK (not depicted). These results indicate that DP signaling is mediated via the p38 and p44/42 MAPK pathways in a cell type–specific manner. We further confirmed the above findings by analyzing the effects of specific p38 MAPK inhibitor, SB203580, at varying concentrations, on PGD2-induced COX-2 expression in NIH-3T3 cells. The results show that SB203580 inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (Fig. 4 D). Most importantly, we found that rUG treatment inhibits PGD2-stimulated tyrosine phosphorylation of both p38 and p44/42 MAPK in BSM-2146 (Fig. 4 E) and p38 MAPK in NIH-3T3 cells (Fig. 4 F).


Uteroglobin represses allergen-induced inflammatory response by blocking PGD2 receptor-mediated functions.

Mandal AK, Zhang Z, Ray R, Choi MS, Chowdhury B, Pattabiraman N, Mukherjee AB - J. Exp. Med. (2004)

Molecular mechanism(s) of DP signaling is cell type specific. PGD2 stimulation of BSM-2146 cells induces tyrosine phosphorylation of p38 (A) and p44/42 (B), whereas in NIH-3T3 cells such treatment leads to tyrosine phosphorylation of only p38 MAPK (C). Moreover, p38 MAPK inhibitor, SB203580, inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (D). In BSM-2146 cells, rUG (1 μM) treatment inhibits PGD2-mediated phosphorylation of both p44/42 and p38 MAPK (E), and in NIH-3T3 cells rUG inhibits phosphorylation of only p38 MAPK (F).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211805&req=5

fig4: Molecular mechanism(s) of DP signaling is cell type specific. PGD2 stimulation of BSM-2146 cells induces tyrosine phosphorylation of p38 (A) and p44/42 (B), whereas in NIH-3T3 cells such treatment leads to tyrosine phosphorylation of only p38 MAPK (C). Moreover, p38 MAPK inhibitor, SB203580, inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (D). In BSM-2146 cells, rUG (1 μM) treatment inhibits PGD2-mediated phosphorylation of both p44/42 and p38 MAPK (E), and in NIH-3T3 cells rUG inhibits phosphorylation of only p38 MAPK (F).
Mentions: Although our results demonstrate that PGD2 stimulates COX-2 expression via DP, the molecular mechanisms of DP signaling, until now, remained unclear. Thus, we studied the mechanism(s) of DP signaling using our in vitro experimental system. The prostanoids signal through specific G protein–coupled receptors, and it has been reported that many agonists of these receptors activate the MAPK pathway (28). Thus, we analyzed the phosphorylation-dependent activation of kinase pathways. We treated the cells with PGD2 for varying lengths of time and analyzed tyrosine phosphorylation of MAPK by Western blot analysis using anti–phospho p38-MAPK (Tyr-182) and anti–phospho p44/42-MAPK (Tyr-204) antibodies. PGD2 stimulates the phosphorylation of both p38- (Fig. 4 A) and p44/42-MAPK (Fig. 4 B) in BSM-2146 cells, whereas in NIH-3T3 cells PGD2 stimulates the phosphorylation of p38 (Fig. 4 C) but not p44/42 MAPK (not depicted). These results indicate that DP signaling is mediated via the p38 and p44/42 MAPK pathways in a cell type–specific manner. We further confirmed the above findings by analyzing the effects of specific p38 MAPK inhibitor, SB203580, at varying concentrations, on PGD2-induced COX-2 expression in NIH-3T3 cells. The results show that SB203580 inhibits PGD2-induced COX-2 mRNA expression in a dose-dependent manner (Fig. 4 D). Most importantly, we found that rUG treatment inhibits PGD2-stimulated tyrosine phosphorylation of both p38 and p44/42 MAPK in BSM-2146 (Fig. 4 E) and p38 MAPK in NIH-3T3 cells (Fig. 4 F).

Bottom Line: These effects are abrogated by recombinant UG treatment.Here we report that DP signaling is mediated via p38 mitogen-activated protein kinase, p44/42 mitogen-activated protein kinase, and protein kinase C pathways in a cell type-specific manner leading to nuclear factor-kappaB activation stimulating COX-2 gene expression.Further, we found that recombinant UG blocks DP-mediated nuclear factor-kappaB activation and suppresses COX-2 gene expression.

View Article: PubMed Central - PubMed

Affiliation: Bldg. 10, Rm. 9S241, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.

ABSTRACT
Uteroglobin (UG) is an antiinflammatory protein secreted by the epithelial lining of all organs communicating with the external environment. We reported previously that UG-knockout mice manifest exaggerated inflammatory response to allergen, characterized by increased eotaxin and Th2 cytokine gene expression, and eosinophil infiltration in the lungs. In this study, we uncovered that the airway epithelia of these mice also express high levels of cyclooxygenase (COX)-2, a key enzyme for the production of proinflammatory lipid mediators, and the bronchoalveolar lavage fluid (BALF) contain elevated levels of prostaglandin D2. These effects are abrogated by recombinant UG treatment. Although it has been reported that prostaglandin D2 mediates allergic inflammation via its receptor, DP, neither the molecular mechanism(s) of DP signaling nor the mechanism by which UG suppresses DP-mediated inflammatory response are clearly understood. Here we report that DP signaling is mediated via p38 mitogen-activated protein kinase, p44/42 mitogen-activated protein kinase, and protein kinase C pathways in a cell type-specific manner leading to nuclear factor-kappaB activation stimulating COX-2 gene expression. Further, we found that recombinant UG blocks DP-mediated nuclear factor-kappaB activation and suppresses COX-2 gene expression. We propose that UG is an essential component of a novel innate homeostatic mechanism in the mammalian airways to repress allergen-induced inflammatory responses.

Show MeSH
Related in: MedlinePlus