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Group V Secretory PLA2 Alternative Activation of Macrophages Contributes to Pulmonary Inflammation Induced by House Dust Mite
AB270 Abstracts
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Group V Secretory PLA2 Alternative Activation of Macrophages Contributes to Pulmonary Inflammation Induced by House Dust Mite B. Balestrieri, G. Giannattasio, D. Fujioka, S. Ota, H. Katz, J. A. Boyce; Brigham and Women’s Hospital/Harvard Medical School, Boston, MA. RATIONALE: Group V secretory phospholipase A2 (sPLA2) regulates phagocytosis of pathogens by macrophages and processing of house dust mite allergens by dendritic cells. Because mice lacking group V sPLA2 showed markedly diminished pulmonary inflammation and Th2-polarized immune responses to an extract (Df) of house dust mite Dermatophagoides farinae, we evaluated the role of group V sPLA2 in alternative activation of macrophages, an important event in allergic pulmonary inflammation. METHODS: WT and group V sPLA2 (Pla2g5)-/- littermates were challenged intranasally with Df twice/week for 3 weeks and lung histological analysis was performed. Lung mRNA encoding alternative macrophage markers Relm-a, and YM-1 was measured by qPCR. Lung interstitial macrophages (IM) and bone marrow alternative activated macrophages (BMAAm) were analyzed by FACS. BMAAm were adoptively transferred by i.v. injection. RESULTS: Compared with saline-treated controls, the expression of Relm-a was strongly induced in the lung of Df-treated WT mice and the mRNA of Relm-a, and YM-1 were higher in the lung of Df-treated WT mice than in Df-treated Pla2g5-/- mice. Df-treated Pla2g5-/- IM had decreased expression of Relm-a, CD206 and CD204 compared to Df-treated WT IM. Pla2g5-/- BMAAm had also lower expression of those markers compared to WT BMAAm. When transferred in WT mice, WT BMAAm were able to induce more pulmonary inflammation than Pla2g5-/- BMAAm. CONCLUSIONS: Intrinsic expression of group V sPLA2 is essential for alternate activation of macrophages and regulates allergen-induced lung inflammation. These data suggest that group V sPLA2 and AAm represent a therapeutic target for treatment of allergic and inflammatory disorders of the lung.
J ALLERGY CLIN IMMUNOL FEBRUARY 2011
1048
Impaired Lymph-Node Homing of Dendritic Cells (DC) in Allergen-Challenged Surfactant Protein D Deficient (SPD-/-) Mice is Associated with Lack of Ccr7 and Reduced Expression of Signal Regulatory Protein-Alpha (Sirp-a) L. R. Forbes1,2, C. Koziol-White2, B. Ducka2, M. Fehrenbach2, A. Haczku2; 1Children’s Hospital of Philadelphia, Philadelphia, PA, 2University of Pennsylvania, Philadelphia, PA. RATIONALE: We previously showed that the immunoprotective epithelial molecule, SP-D, constitutively engages SIRP-a on the surface of pulmonary innate immune cells. SIRP-a has been implicated in lymph-node homing of DC. We hypothesized that myeloid DC accumulation in the airways of SP-D-/- mice is due, at least partly, to a failure of lymph node-directed DC migration. METHODS: Wild-type (wt) and SPD-/- mice received sensitization and challenge with Aspergillus fumigatus (Af) and were i.v. injected with a phagocyte label, PKH-26. Bronchoalveolar lavage fluid (BAL) was harvested before (0h), 24h and 96h after Af inhalation. Immunohistochemistry and multicolor FACS analysis was used to assess BAL CD11b1/CD11c1/MHC-II1 DC for expression of SIRP-a, Ccr4 (mediates epithelial migration) and Ccr7 (mediates lymph node homing). RESULTS: Bone-marrow derived (CD11b1) phagocytic (PKH1), Ccr41 DC gradually accumulated up to 96h after Af inhalation. The number of Ccr71 DC peaked at 24h but disappeared from the airways by 96h after Af suggesting a lymph-node directed efflux. Lack of SP-D resulted in increased numbers of myeloid DC in the airways and decreased DC recovery from the thoracic lymph nodes. In comparison with wt, SP-D-/- DC had strikingly diminished Ccr7 expression 24h after Af challenge. This was associated with a reduced SIRP-a1 cells in the BAL of SP-D-/- mice. CONCLUSIONS: Migration of activated myeloid DC to the epithelium is followed by lymph node homing of the Ccr71 cells after Af challenge. We propose that an impaired lymph node homing of DC in SP-D-/- mice is due to lack of SIRP-a ligation and inability to express Ccr7.
TUESDAY
1047
Group V Secretory PLA2 Alternative Activation of Macrophages Contributes to Pulmonary Inflammation Induced by House Dust Mite B. Balestrieri, G. Giannattasio, D. Fujioka, S. Ota, H. Katz, J. A. Boyce; Brigham and Women’s Hospital/Harvard Medical School, Boston, MA. RATIONALE: Group V secretory phospholipase A2 (sPLA2) regulates phagocytosis of pathogens by macrophages and processing of house dust mite allergens by dendritic cells. Because mice lacking group V sPLA2 showed markedly diminished pulmonary inflammation and Th2-polarized immune responses to an extract (Df) of house dust mite Dermatophagoides farinae, we evaluated the role of group V sPLA2 in alternative activation of macrophages, an important event in allergic pulmonary inflammation. METHODS: WT and group V sPLA2 (Pla2g5)-/- littermates were challenged intranasally with Df twice/week for 3 weeks and lung histological analysis was performed. Lung mRNA encoding alternative macrophage markers Relm-a, and YM-1 was measured by qPCR. Lung interstitial macrophages (IM) and bone marrow alternative activated macrophages (BMAAm) were analyzed by FACS. BMAAm were adoptively transferred by i.v. injection. RESULTS: Compared with saline-treated controls, the expression of Relm-a was strongly induced in the lung of Df-treated WT mice and the mRNA of Relm-a, and YM-1 were higher in the lung of Df-treated WT mice than in Df-treated Pla2g5-/- mice. Df-treated Pla2g5-/- IM had decreased expression of Relm-a, CD206 and CD204 compared to Df-treated WT IM. Pla2g5-/- BMAAm had also lower expression of those markers compared to WT BMAAm. When transferred in WT mice, WT BMAAm were able to induce more pulmonary inflammation than Pla2g5-/- BMAAm. CONCLUSIONS: Intrinsic expression of group V sPLA2 is essential for alternate activation of macrophages and regulates allergen-induced lung inflammation. These data suggest that group V sPLA2 and AAm represent a therapeutic target for treatment of allergic and inflammatory disorders of the lung.
J ALLERGY CLIN IMMUNOL FEBRUARY 2011
1048
Impaired Lymph-Node Homing of Dendritic Cells (DC) in Allergen-Challenged Surfactant Protein D Deficient (SPD-/-) Mice is Associated with Lack of Ccr7 and Reduced Expression of Signal Regulatory Protein-Alpha (Sirp-a) L. R. Forbes1,2, C. Koziol-White2, B. Ducka2, M. Fehrenbach2, A. Haczku2; 1Children’s Hospital of Philadelphia, Philadelphia, PA, 2University of Pennsylvania, Philadelphia, PA. RATIONALE: We previously showed that the immunoprotective epithelial molecule, SP-D, constitutively engages SIRP-a on the surface of pulmonary innate immune cells. SIRP-a has been implicated in lymph-node homing of DC. We hypothesized that myeloid DC accumulation in the airways of SP-D-/- mice is due, at least partly, to a failure of lymph node-directed DC migration. METHODS: Wild-type (wt) and SPD-/- mice received sensitization and challenge with Aspergillus fumigatus (Af) and were i.v. injected with a phagocyte label, PKH-26. Bronchoalveolar lavage fluid (BAL) was harvested before (0h), 24h and 96h after Af inhalation. Immunohistochemistry and multicolor FACS analysis was used to assess BAL CD11b1/CD11c1/MHC-II1 DC for expression of SIRP-a, Ccr4 (mediates epithelial migration) and Ccr7 (mediates lymph node homing). RESULTS: Bone-marrow derived (CD11b1) phagocytic (PKH1), Ccr41 DC gradually accumulated up to 96h after Af inhalation. The number of Ccr71 DC peaked at 24h but disappeared from the airways by 96h after Af suggesting a lymph-node directed efflux. Lack of SP-D resulted in increased numbers of myeloid DC in the airways and decreased DC recovery from the thoracic lymph nodes. In comparison with wt, SP-D-/- DC had strikingly diminished Ccr7 expression 24h after Af challenge. This was associated with a reduced SIRP-a1 cells in the BAL of SP-D-/- mice. CONCLUSIONS: Migration of activated myeloid DC to the epithelium is followed by lymph node homing of the Ccr71 cells after Af challenge. We propose that an impaired lymph node homing of DC in SP-D-/- mice is due to lack of SIRP-a ligation and inability to express Ccr7.
TUESDAY