Related Experiment Videos
Microglia activation is essential for BMP7-mediated retinal reactive gliosis
Subramanian Dharmarajan1,2, Debra L Fisk3, Christine M Sorenson4
1Department of Biology, Indiana University-Purdue University Indianapolis, 723 W Michigan St, SL306, Indianapolis, IN, 46202, USA.
Background:
Our previous studies have shown that BMP7 is able to trigger activation of retinal macroglia. However, these studies showed the responsiveness of Müller glial cells and retinal astrocytes in vitro was attenuated in comparison to those in vivo, indicating other retinal cell types may be mediating the response of the macroglial cells to BMP7. In this study, we test the hypothesis that BMP7-mediated gliosis is the result of inflammatory signaling from retinal microglia.
Methods:
Adult mice were injected intravitreally with BMP7 and eyes harvested 1, 3, or 7 days postinjection. Some mice were treated with PLX5622 (PLX) to ablate microglia and were subsequently injected with control or BMP7. Processed tissue was analyzed via immunofluorescence, RT-qPCR, or ELISA. In addition, cultures of retinal microglia were treated with vehicle, lipopolysaccharide, or BMP7 to determine the effects of BMP7-isolated cells.
Results:
Mice injected with BMP7 showed regulation of various inflammatory markers at the RNA level, as well as changes in microglial morphology. Isolated retinal microglia also showed an upregulation of BMP-signaling components following treatment. In vitro treatment of retinal astrocytes with conditioned media from activated microglia upregulated RNA levels of gliosis markers. In the absence of microglia, the mouse retina showed a subdued gliosis and inflammatory response when exposed to BMP7.
Conclusions:
Gliosis resulting from BMP7 is mediated through an inflammatory response from retinal microglia.
Insights
Bone morphogenetic protein 7 (BMP7) triggers retinal gliosis via inflammatory signals from microglia. Ablating microglia significantly reduces BMP7-induced gliosis and inflammation in the mouse retina.
Area of Science:
- Ophthalmology
- Neuroscience
- Immunology
Background:
- Previous studies indicated Bone Morphogenetic Protein 7 (BMP7) activates retinal macroglia.
- In vitro studies showed attenuated Müller glial cell and retinal astrocyte responses to BMP7 compared to in vivo.
- This suggests other retinal cell types mediate BMP7's macroglial response.
Purpose of the Study:
- To test the hypothesis that BMP7-mediated gliosis results from inflammatory signaling by retinal microglia.
- To investigate the role of microglia in BMP7-induced retinal responses.
Main Methods:
- Adult mice received intravitreal BMP7 injections; eyes were harvested at 1, 3, or 7 days.
- Microglia were ablated using PLX5622 (PLX) before BMP7 or control injection.
- Tissue analysis included immunofluorescence, RT-qPCR, and ELISA; isolated retinal microglia were also treated with BMP7.
Main Results:
- BMP7 injection altered inflammatory markers and microglial morphology in mice.
- Isolated retinal microglia showed upregulated BMP-signaling components after BMP7 treatment.
- Microglia-conditioned media induced gliosis markers in retinal astrocytes; gliosis was subdued in microglia-ablated retinas.
Conclusions:
- BMP7-induced gliosis is mediated by inflammatory signaling from retinal microglia.
- Retinal microglia play a crucial role in mediating BMP7's effects on the retina.