Biphasic Effect of Prostaglandin E2 on Osteoclast Formation in Spleen Cell Cultures: Role of the EP2 Receptor

Inflammation after intracerebral hemorrhage (ICH) is a key component to secondary brain injury, a major cause of morbidity and disability after ICH. Prostaglandin E2 (PGE 2 ) plays an important role in modulating inflammatory responses and in many neurologic disorders. PGE 2 binds with high affinity to the G-protein-coupled receptors EP1, EP2, EP3, and EP4, which collectively mediate its neuroimmunomodulatory effects. We and others have documented that the EP2 receptor mediates the neuroprotective properties of PGE 2 in neuronal cultures and in the middle cerebral artery occlusion model of ischemia/reperfusion-induced brain injury. The present study aimed to investigate the role of EP2 receptor signaling on anatomical and functional outcomes after ICH. The collagenase model was used to induce an ICH in wildtype (WT) and EP2 -/- mice (n=8-11/group). After 72h, mice were sacrificed and brains collected for Cresyl Violet staining and lesion volume quantification. The EP2 -/- displayed significantly reduced lesion volumes when compared to WT controls (p<0.005). The EP2 -/- also showed reduced cortical and striatal microglial activation (p<0.05), and less cortical astrocyte activation (p<0.05). Collectively, these results suggest that PGE 2 -EP2 receptor signaling aggravates ICH-induced brain injury in vivo, which is in contrast to previous reports in stroke models, highlighting the dynamic role of the EP2 receptor in modulating inflammatory responses following brain damage. Further investigations are necessary in order to identify the mechanism of EP2-mediated hematoma resolution. Additional studies using a selective EP2 receptor antagonist could lead to the development of improved drugs that minimize the side effects often associated with anti-inflammatory medications in order to help prevent or improve neurologic recovery following ICH.

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Knockout of the Murine Prostaglandin EP2 Receptor Impairs Osteoclastogenesis in Vitro*

Endocrinology ◽

10.1210/endo.141.6.7518 ◽

2000 ◽

Vol 141 (6) ◽

pp. 2054-2061 ◽

Cited By ~ 72

Author(s):

Xiaodong Li ◽

Yosuke Okada ◽

Carol C. Pilbeam ◽

Joseph A. Lorenzo ◽

Christopher R. J. Kennedy ◽

...

Keyword(s):

Spleen Cell ◽

Cell Cultures ◽

Messenger Rna ◽

Osteoblastic Cells ◽

Spleen Cells ◽

Dihydroxyvitamin D ◽

Macrophage Colony Stimulating Factor ◽

Macrophage Colony ◽

Ep2 Receptor

Abstract Prostaglandin E2 (PGE2) stimulates the formation of osteoclast-like tartrate-resistant acid phosphatase-positive multinucleated cells (TRAP + MNC) in vitro. This effect likely results from stimulation of adenylyl cyclase, which is mediated by two PGE2 receptors, designated EP2 and EP4. We used cells from mice in which the EP2 receptor had been disrupted to test its role in the formation of TRAP + MNC. EP2 heterozygous (±) mice in a C57BL/6 x 129/SvEv background were bred to produce homozygous null (EP2 −/−) and wild-type (EP2 +/+) mice. PGE2, PTH, or 1,25 dihydroxyvitamin D increased TRAP+ MNC in 7-day cultures of bone marrow cells from EP2 +/+ mice. In cultures from EP2 −/− animals, responses to PGE2, PTH, and 1,25 dihydroxyvitamin D were reduced by 86%, 58%, and 50%, respectively. A selective EP4 receptor antagonist (EP4RA) further inhibited TRAP+ MNC formation in both EP2 +/+ and EP2 −/− cultures. In cocultures of spleen and calvarial osteoblastic cells, the response to PGE2 or PTH was reduced by 92% or 85% when both osteoblastic cells and spleen cells were from EP2− /− mice, by 88% or 68% when only osteoblastic cells were from EP2 −/− mice and by 58% or 35% when only spleen cells were from EP2 −/− mice. PGE2 increased receptor activator of nuclear factor (NF)-kB ligand (RANKL) messenger RNA expression in osteoblastic and bone marrow cell cultures from EP2 +/+ mice 2-fold but had little effect on cells from EP2 −/− mice. Spleen cells cultured with RANKL and macrophage colony stimulating factor produced TRAP+ MNC. PGE2 increased the number of TRAP+ MNC in spleen cell cultures from EP2 +/+ mice but not in cultures from EP2 −/− mice. EP4RA had no effect on the PGE2 response in spleen cell cultures. PGE2 decreased the expression of messenger RNA for granulocyte-macrophage colony stimulating factor in spleen cell cultures from EP2+ /+ mice but had little effect on cells from EP2 −/− mice. These data demonstrate that the prostaglandin EP2 receptor plays a role in the formation of osteoclast-like cells in vitro. A major defect in EP2 −/− mice appears to be in the capacity of osteoblastic cells to stimulate osteoclast formation. In addition, there appears to be a defect in the response of cells of the osteoclastic lineage to PGE2 in EP2 −/− mice.

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Protective Role of Nitric Oxide inStaphylococcus aureus Infection in Mice

Infection and Immunity ◽

10.1128/iai.66.3.1017-1022.1998 ◽

1998 ◽

Vol 66 (3) ◽

pp. 1017-1022 ◽

Cited By ~ 65

Author(s):

Sanae Sasaki ◽

Tomisato Miura ◽

Shinsuke Nishikawa ◽

Kyogo Yamada ◽

Mayuko Hirasue ◽

...

Keyword(s):

Nitric Oxide ◽

Spleen Cell ◽

Cell Cultures ◽

Protective Role ◽

Inos Mrna ◽

No Production ◽

Necrosis Factor Alpha ◽

Tnf Α ◽

Ifn Γ

ABSTRACT This study was carried out to determine the role of nitric oxide (NO) in Staphylococcus aureus infection in mice. NO production in spleen cell cultures was induced by heat-killed S. aureus. Expression of mRNA of the inducible isoform of NO synthase (iNOS) was induced in the spleens and kidneys of S. aureus-infected mice. When mice were treated with monoclonal antibodies (MAbs) against tumor necrosis factor alpha (TNF-α) or gamma interferon (IFN-γ) before S. aureus infection, the induction of iNOS mRNA expression in the kidneys was inhibited. These MAbs also inhibited NO production in spleen cell cultures stimulated with heat-killed S. aureus. NO production in the spleen cell cultures and levels of urinary nitrate plus nitrite were suppressed by treatment with aminoguanidine (AG), a selective inhibitor of iNOS. The survival rates of AG-treated mice were significantly decreased by either lethal or sublethal S. aureusinfections. However, an effect of AG administration on bacterial growth was not observed in the spleens and kidneys of mice during either type of infection. Production of TNF-α and IFN-γ was not affected by AG treatment in vitro and in vivo. These results suggest that NO plays an important role in protection from lethality by the infection, but the protective role of NO in host resistance against S. aureusinfection was not proved. Moreover, our results show that TNF-α and IFN-γ regulate NO production while NO may not be involved in the regulation of the production of these cytokines during S. aureus infection.

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Reduction of Allergic Lung Disease by Mucosal Application of Toxoplasma gondii-Derived Molecules: Possible Role of Carbohydrates

Frontiers in Immunology ◽

10.3389/fimmu.2020.612766 ◽

2021 ◽

Vol 11 ◽

Author(s):

Elke Korb ◽

Mirjana Drinić ◽

Angelika Wagner ◽

Nora Geissler ◽

Aleksandra Inic-Kanada ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Spleen Cell ◽

Cell Cultures ◽

Ex Vivo ◽

Inflammatory Cells ◽

Heat Inactivation ◽

Parasitic Infections ◽

Type 2 Cytokines

BackgroundThe hygiene hypothesis suggests a link between parasitic infections and immune disorders, such as allergic diseases. We previously showed that infection with Toxoplasma gondii or systemic application of T. gondii tachyzoites lysate antigen (TLA) in a prophylactic, but not therapeutic protocol, prevented allergic airway inflammation in mice. Here we tested the effect of prophylactic and therapeutic application of TLA via the mucosal route.MethodsMice were intranasally treated with TLA either i) prior to sensitization, ii) during sensitization and challenge, or iii) after sensitization with ovalbumin (OVA). Recruitment of inflammatory cells to the lung, cytokine levels in restimulated lung and spleen cell cultures as well as levels of OVA-specific antibodies in serum were measured. In parallel, the effect of native TLA, heat-inactivated (hiTLA) or deglycosylated TLA (dgTLA) on sensitized splenocytes was evaluated ex vivo.ResultsWhen applied together with OVA i) during systemic sensitization and local challenge or ii) exclusively during local challenge, TLA reduced infiltration of eosinophils into the lung, OVA-specific type 2 cytokines in restimulated lung cell cultures, and partially, type 2 cytokines in restimulated spleen cell cultures in comparison to allergic controls. No beneficial effect was observed when TLA was applied prior to the start of sensitization. Analysis of epitope sugars on TLA indicated a high abundance of mannose, fucose, N-acetylglucosamine, and N-acetylgalactosamine. Deglycosylation of TLA, but not heat-inactivation, abolished the potential of TLA to reduce type 2 responses ex vivo, suggesting a significant role of carbohydrates in immunomodulation.ConclusionWe showed that mucosal application of TLA reduced the development of experimental allergy in mice. The beneficial effects depended on the timing of the application in relation to the time point of sensitization. Not only co-application, but also therapy in sensitized/allergic animals with native TLA reduced local allergic responses. Furthermore, we show that TLA is highly glycosylated and glycoconjugates seem to play a role in anti-allergic effects. In summary, given the powerful modulatory effect that TLA exhibits, understanding its exact mechanisms of action may lead to the development of novel immunomodulators in clinical application.

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THYMUS-INDEPENDENT (B) CELL PROLIFERATION IN SPLEEN CELL CULTURES OF MOUSE RADIATION CHIMERAS STIMULATED BY PHYTOHEMAGGLUTININ OR ALLOGENEIC CELLS

Journal of Experimental Medicine ◽

10.1084/jem.136.4.962 ◽

1972 ◽

Vol 136 (4) ◽

pp. 962-967 ◽

Cited By ~ 32

Author(s):

P.-F. Piguet ◽

P. Vassalli

Keyword(s):

T Cell ◽

Spleen Cell ◽

Cell Cultures ◽

Bone Marrow Cells ◽

Spleen Cells ◽

Radiation Chimeras ◽

Lymphocyte Cultures ◽

Mixed Lymphocyte Cultures

Spleen cell cultures of radiation chimeras (thymectomized, lethally irradiated mice repopulated with bone marrow cells and thymocytes bearing different chromosomal markers) were stimulated by phytohemagglutinin (PHA) and F1 allogeneic spleen cells. Karyotypic analyses showed a marked predominance of T mitoses on the 2nd and 3rd days of culture followed by a strong predominance of B mitoses on the 4th and 5th days. Analysis of cells undergoing their first mitoses showed that the majority of T mitoses on day 3 resulted from continuous T cell division, and that most cells entering their first mitoses at that time were of B type. Mixed lymphocyte cultures (MLC) of chimeras immunized against allogeneic spleen cells showed sometimes, but not always, a response different from "primary" MLC, with an earlier and stronger predominance of BM mitoses. The role of stimulated T cells in the induction of B mitoses was shown by (a) the incapacity of T-depleted spleen cells to be stimulated by PHA or in primary or secondary MLC, and (b) the restoration of the mitotic response of B cells to PHA by adding to the T cell-depleted culture either a very small number of T cell (identified by their different karyotype: "in vitro chimeras") or the cell-free supernatant of a 24 hr MLC.

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