Limits...
CD137 ligand activated microglia induces oligodendrocyte apoptosis via reactive oxygen species.

Yeo YA, Martínez Gómez JM, Croxford JL, Gasser S, Ling EA, Schwarz H - J Neuroinflammation (2012)

Bottom Line: CD137L signaling is also important for microglia activation in vivo, since CD137L-deficient mice exhibited profoundly less microglia activation during experimental autoimmune encephalomyelitis (EAE) which is a well-established murine model for neuroinflammation and human multiple sclerosis (MS).In vitro co-culture confirmed that CD137L-activated microglia induces apoptosis in oligodendrocytes, and identified reactive oxygen species as the mechanism of apoptosis induction.These data demonstrate activating effects of CD137L signaling to microglia, and show for the first time that the CD137 receptor/ligand system may be a mediator of neuroinflammatory and neurodegenerative disease, by activating microglia which in turn kill oligodendrocytes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive #14-02T, Singapore, 117599, Singapore.

ABSTRACT
CD137 (4-1BB, TNFRSF9), a member of the tumor necrosis factor (TNF) receptor family, is a potent T cell co-stimulatory molecule. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC) as a transmembrane protein and transmits activating signals into APC. In this study we investigated the effects of CD137L signaling in microglia, the resident APC in the central nervous system. In vitro, the murine microglia cell lines BV-2 and N9, as well as primary murine microglia responded with activation as evidenced by adherence and secretion of proinflammatory cytokines, MMP-9, and soluble intercellular adhesion molecule (ICAM). CD137L signaling is also important for microglia activation in vivo, since CD137L-deficient mice exhibited profoundly less microglia activation during experimental autoimmune encephalomyelitis (EAE) which is a well-established murine model for neuroinflammation and human multiple sclerosis (MS). Also CD137 is expressed in the CNS of mice during EAE. Activated microglia has been reported to mediate the destruction of axonal myelin sheaths and cause the death of oligodendrocytes, the main pathogenic mechanisms in EAE and MS. Corresponding to the lower microglia activation there were also fewer apoptotic oligodendrocytes in the CNS of CD137L-deficient mice. In vitro co-culture confirmed that CD137L-activated microglia induces apoptosis in oligodendrocytes, and identified reactive oxygen species as the mechanism of apoptosis induction. These data demonstrate activating effects of CD137L signaling to microglia, and show for the first time that the CD137 receptor/ligand system may be a mediator of neuroinflammatory and neurodegenerative disease, by activating microglia which in turn kill oligodendrocytes.

Show MeSH

Related in: MedlinePlus

CD137L-activated microglia induces oligodendrocyte apoptosis via ROS. (A) BV-2 cells were cultured on uncoated plates (PBS) or plates coated with Fc or CD137-Fc protein for 24 h, and were then stimulated with 0.4 μg of PMA for 1 h, stained with DHR123 before production of ROS was quantified by flow cytometry. White histogram: No DHR123. The number in the panel indicates the percentage of positive cells. (B) BV-2 cells were co-cultured with OLN93 cells at a 1:1 ratio with or without 10,000 U/mL catalase. The rate of apoptosis of cultures was determined after 24 h by 7-AAD and Annexin V staining. Numbers in quadrants indicate percentages of cells. (C) The percentages of 7-AAD+ OLN93 cells with and without catalase treatment of B are presented as means ± standard deviations of triplicate measurements. * P < 0.05; ** P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3420242&req=5

Figure 5: CD137L-activated microglia induces oligodendrocyte apoptosis via ROS. (A) BV-2 cells were cultured on uncoated plates (PBS) or plates coated with Fc or CD137-Fc protein for 24 h, and were then stimulated with 0.4 μg of PMA for 1 h, stained with DHR123 before production of ROS was quantified by flow cytometry. White histogram: No DHR123. The number in the panel indicates the percentage of positive cells. (B) BV-2 cells were co-cultured with OLN93 cells at a 1:1 ratio with or without 10,000 U/mL catalase. The rate of apoptosis of cultures was determined after 24 h by 7-AAD and Annexin V staining. Numbers in quadrants indicate percentages of cells. (C) The percentages of 7-AAD+ OLN93 cells with and without catalase treatment of B are presented as means ± standard deviations of triplicate measurements. * P < 0.05; ** P < 0.01.

Mentions: CD137L-activated monocytes have been shown to induce apoptosis in of T cells when they are in co-culture, and this cell death was mediated by ROS [24]. Therefore, we hypothesized that a similar mechanism may be responsible for the induction of oligodendrocyte death by CD137L-activated microglia. Indeed, CD137L engagement on BV-2 cells induced ROS production (Figure 5A), and when catalase, a hydrogen peroxide scavenger, was added to the co-culture the killing of oligodendrocytes by activated microglia was prevented (Figure 5B). The percentages of late apoptotic and/or dead OLN93 cells for the different conditions are quantitatively depicted in (Figure 5C).


CD137 ligand activated microglia induces oligodendrocyte apoptosis via reactive oxygen species.

Yeo YA, Martínez Gómez JM, Croxford JL, Gasser S, Ling EA, Schwarz H - J Neuroinflammation (2012)

CD137L-activated microglia induces oligodendrocyte apoptosis via ROS. (A) BV-2 cells were cultured on uncoated plates (PBS) or plates coated with Fc or CD137-Fc protein for 24 h, and were then stimulated with 0.4 μg of PMA for 1 h, stained with DHR123 before production of ROS was quantified by flow cytometry. White histogram: No DHR123. The number in the panel indicates the percentage of positive cells. (B) BV-2 cells were co-cultured with OLN93 cells at a 1:1 ratio with or without 10,000 U/mL catalase. The rate of apoptosis of cultures was determined after 24 h by 7-AAD and Annexin V staining. Numbers in quadrants indicate percentages of cells. (C) The percentages of 7-AAD+ OLN93 cells with and without catalase treatment of B are presented as means ± standard deviations of triplicate measurements. * P < 0.05; ** P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3420242&req=5

Figure 5: CD137L-activated microglia induces oligodendrocyte apoptosis via ROS. (A) BV-2 cells were cultured on uncoated plates (PBS) or plates coated with Fc or CD137-Fc protein for 24 h, and were then stimulated with 0.4 μg of PMA for 1 h, stained with DHR123 before production of ROS was quantified by flow cytometry. White histogram: No DHR123. The number in the panel indicates the percentage of positive cells. (B) BV-2 cells were co-cultured with OLN93 cells at a 1:1 ratio with or without 10,000 U/mL catalase. The rate of apoptosis of cultures was determined after 24 h by 7-AAD and Annexin V staining. Numbers in quadrants indicate percentages of cells. (C) The percentages of 7-AAD+ OLN93 cells with and without catalase treatment of B are presented as means ± standard deviations of triplicate measurements. * P < 0.05; ** P < 0.01.
Mentions: CD137L-activated monocytes have been shown to induce apoptosis in of T cells when they are in co-culture, and this cell death was mediated by ROS [24]. Therefore, we hypothesized that a similar mechanism may be responsible for the induction of oligodendrocyte death by CD137L-activated microglia. Indeed, CD137L engagement on BV-2 cells induced ROS production (Figure 5A), and when catalase, a hydrogen peroxide scavenger, was added to the co-culture the killing of oligodendrocytes by activated microglia was prevented (Figure 5B). The percentages of late apoptotic and/or dead OLN93 cells for the different conditions are quantitatively depicted in (Figure 5C).

Bottom Line: CD137L signaling is also important for microglia activation in vivo, since CD137L-deficient mice exhibited profoundly less microglia activation during experimental autoimmune encephalomyelitis (EAE) which is a well-established murine model for neuroinflammation and human multiple sclerosis (MS).In vitro co-culture confirmed that CD137L-activated microglia induces apoptosis in oligodendrocytes, and identified reactive oxygen species as the mechanism of apoptosis induction.These data demonstrate activating effects of CD137L signaling to microglia, and show for the first time that the CD137 receptor/ligand system may be a mediator of neuroinflammatory and neurodegenerative disease, by activating microglia which in turn kill oligodendrocytes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive #14-02T, Singapore, 117599, Singapore.

ABSTRACT
CD137 (4-1BB, TNFRSF9), a member of the tumor necrosis factor (TNF) receptor family, is a potent T cell co-stimulatory molecule. CD137 ligand (CD137L) is expressed by antigen presenting cells (APC) as a transmembrane protein and transmits activating signals into APC. In this study we investigated the effects of CD137L signaling in microglia, the resident APC in the central nervous system. In vitro, the murine microglia cell lines BV-2 and N9, as well as primary murine microglia responded with activation as evidenced by adherence and secretion of proinflammatory cytokines, MMP-9, and soluble intercellular adhesion molecule (ICAM). CD137L signaling is also important for microglia activation in vivo, since CD137L-deficient mice exhibited profoundly less microglia activation during experimental autoimmune encephalomyelitis (EAE) which is a well-established murine model for neuroinflammation and human multiple sclerosis (MS). Also CD137 is expressed in the CNS of mice during EAE. Activated microglia has been reported to mediate the destruction of axonal myelin sheaths and cause the death of oligodendrocytes, the main pathogenic mechanisms in EAE and MS. Corresponding to the lower microglia activation there were also fewer apoptotic oligodendrocytes in the CNS of CD137L-deficient mice. In vitro co-culture confirmed that CD137L-activated microglia induces apoptosis in oligodendrocytes, and identified reactive oxygen species as the mechanism of apoptosis induction. These data demonstrate activating effects of CD137L signaling to microglia, and show for the first time that the CD137 receptor/ligand system may be a mediator of neuroinflammatory and neurodegenerative disease, by activating microglia which in turn kill oligodendrocytes.

Show MeSH
Related in: MedlinePlus