Bim expression modulates the pro-inflammatory phenotype of retinal astroglial cells

Artesunate mitigates choroidal neovascularization and scar formation

Angiogenesis, although required during eye development, has a causative effect in many ocular diseases. Aberrant neovascularization contributes to the progression of neovascular age-related macular degeneration (nAMD), a vision-threaten disease in aging Americans. Since increased amounts of vascular endothelial growth factor (VEGF) drives neovascularization during the pathogenesis of nAMD the standard of care are anti-VEGF therapies attempt to disrupt this vicious cycle. These current anti-VEGF therapies try to maintain vascular homeostasis while abating aberrant neovascularization but regrettably don't prevent fibrosis or scar formation. In addition, some patients demonstrate an incomplete response to anti-VEGF therapy as demonstrated by progressive vision loss. Here, we show choroidal endothelial cells (ChEC) incubated with artesunate demonstrated decreased migration and inflammatory and fibrotic factor expression, which corresponded with decreased sprouting in a choroid/retinal pigment epithelium (RPE) explant sprouting angiogenesis assay. To assess the efficacy of artesunate to curtail neovascularization in vivo, we utilized laser photocoagulation-induced rupture of the Bruch's membrane to induce choroidal neovascularization (CNV). Artesunate significantly inhibited CNV and the accompanying fibrotic scar, perhaps due in part to its ability to inhibit mononuclear phagocyte (MP) recruitment. Thus, artesunate shows promise in inhibiting both CNV and fibrosis.

Calcitonin gene-related peptide regulates spinal microglial activation through the histone H3 lysine 27 trimethylation via enhancer of zeste homolog-2 in rats with neuropathic pain

BACKGROUND

Calcitonin gene-related peptide (CGRP) as a mediator of microglial activation at the transcriptional level may facilitate nociceptive signaling. Trimethylation of H3 lysine 27 (H3K27me3) by enhancer of zeste homolog 2 (EZH2) is an epigenetic mark that regulates inflammatory-related gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K27me3 in microglial activation after nerve injury, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain.

METHODS

Microglial cells (BV2) were treated with CGRP and differentially enrichments of H3K27me3 on gene promoters were examined using ChIP-seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on microglial activation and EZH2/H3K27me3 signaling in CCI-induced neuropathic pain.

RESULTS

Overexpressions of EZH2 and H3K27me3 were confirmed in spinal microglia of CCI rats by immunofluorescence. CGRP treatment induced the increased of H3K27me3 expression in the spinal dorsal horn and cultured microglial cells (BV2) through EZH2. ChIP-seq data indicated that CGRP significantly altered H3K27me3 enrichments on gene promoters in microglia following CGRP treatment, including 173 gaining H3K27me3 and 75 losing this mark, which mostly enriched in regulation of cell growth, phagosome, and inflammation. qRT-PCR verified expressions of representative candidate genes (TRAF3IP2, BCL2L11, ITGAM, DAB2, NLRP12, WNT3, ADAM10) and real-time cell analysis (RTCA) verified microglial proliferation. Additionally, CGRP treatment and CCI increased expressions of ITGAM, ADAM10, MCP-1, and CX3CR1, key mediators of microglial activation in spinal dorsal horn and cultured microglial cells. Such increased effects induced by CCI were suppressed by CGRP antagonist and EZH2 inhibitor, which were concurrently associated with the attenuated mechanical and thermal hyperalgesia in CCI rats.

CONCLUSION

Our findings highly indicate that CGRP is implicated in the genesis of neuropathic pain through regulating microglial activation via EZH2-mediated H3K27me3 in the spinal dorsal horn.