Evolution of Otx paralogue usages in early patterning of the vertebrate head

AbstractTo assess evolutional changes in the expression pattern of Otx paralogues, expression analyses were undertaken in fugu, bichir, skate and lamprey. Together with those in model vertebrates, the comparison suggested that a gnathostome ancestor would have utilized all of Otx1, Otx2 and Otx5 paralogues in organizer and anterior mesendoderm for head development. In this animal, Otx1 and Otx2 would have also functioned in specification of the anterior neuroectoderm at presomite stage and subsequent development of forebrain/midbrain at somite stage, while Otx5 expression would have already been specialized in epiphysis and eyes. Otx1 and Otx2 functions in anterior neuroectoderm and brain of the gnathostome ancestor would have been differentially maintained by Otx1 in a basal actinopterygian and by Otx2 in a basal sarcopterygian. Otx5 expression in head organizer and anterior mesendoderm seems to have been lost in the teleost lineage after divergence of bichir, and also from the amniotes after divergence of amphibians as independent events. Otx1 expression was lost from the organizer in the tetrapod lineage. In contrast, in a teleost ancestor prior to whole genome duplication, Otx1 and Otx2 would have both been expressed in the dorsal margin of blastoderm, embryonic shield, anterior mesendoderm, anterior neuroectoderm and forebrain/midbrain, at respective stages of head development. Subsequent whole genome duplication and the following genome changes would have caused different Otx paralogue usages in each teleost lineage. Lampreys also have three Otx paralogues; their sequences are highly diverged from gnathostome cognates, but their expression pattern is well related to those of skate Otx cognates

Changes in the deep vasculature assessed using anterior segment OCT angiography following trabecular meshwork targeted minimally invasive glaucoma surgery

The effect of trabecular meshwork (TM)-targeted minimally invasive glaucoma surgery (MIGS) on the vasculature assessed using anterior segment (AS)-optical coherence tomography angiography (OCTA) has not been established. In this prospective, longitudinal study, we investigated changes in the deep vasculature following TM-targeted MIGS using AS-OCTA for open-angle glaucoma in 31 patients. AS-OCTA images of the sclera and conjunctiva at the nasal corneal limbus were acquired preoperatively and 3 months postoperatively, and the vessel densities (VDs) of the superficial (conjunctival) and deep (intrascleral) layers were calculated. The VDs before and after MIGS were compared, and the factors associated with the change in VD following MIGS were analyzed. The mean deep VD decreased from 11.98 ± 6.80% at baseline to 10.42 ± 5.02% postoperatively (P = 0.044), but superficial VD did not change (P = 0.73). The multivariate stepwise regression analysis revealed that deep VD reduction was directly associated with IOP reduction (P < 0.001) and preoperative IOP (P = 0.007) and inversely associated with preoperative deep VD (P < 0.001). The deep VD reduction following MIGS was significant in the successful group (21 eyes) (P = 0.032) but not in the unsuccessful group (10 eyes) (P = 0.49). The deep VDs assessed using AS-OCTA decreased following TM-targeted MIGS, especially in the eyes with good surgical outcomes

Prediction of trabecular meshwork-targeted micro-invasive glaucoma surgery outcomes using anterior segment OCT angiography

前眼部OCTAを用いた線維柱帯切開術効果予測 --房水主流出路の可視化による緑内障手術予後予測の可能性--. 京都大学プレスリリース. 2021-09-09.We performed a prospective, longitudinal study to investigate the association between the preoperative intrascleral vasculature assessed using anterior segment (AS)-optical coherence tomography angiography (OCTA) and surgical outcomes of trabecular meshwork-targeted micro- or minimally invasive glaucoma surgery (MIGS). We included 37 patients with primary open-angle glaucoma. Preoperative AS-OCTA images of the sclero-conjunctiva of the nasal corneal limbus were acquired in the superficial (conjunctival) and deep (intrascleral) layers. The vessel densities (VDs) of each layer were measured separately in the entire area, limbal side, and fornix area. Surgical success was determined by postoperative intraocular pressure (IOP) and IOP reduction. Twenty-three and 14 eyes were classified as having successful and unsuccessful outcomes, respectively. The deep VDs of the entire area and fornix area were significantly lower in the successful group (P = 0.031 and P = 0.009). The success rate was significantly higher for eyes with a lower deep VD than for eyes with a higher deep VD. A greater IOP reduction was significantly associated with lower deep VD in the fornix area (P = 0.022) and higher preoperative IOP (P < 0.001). These results indicate that intrascleral vasculature assessed using preoperative AS-OCTA was negatively correlated with surgical success and IOP reduction resulting from trabecular meshwork-targeted MIGS. AS-OCTA images might help predict MIGS outcomes

The formation of an angiogenic astrocyte template is regulated by the neuroretina in a HIF-1-dependent manner

AbstractThe vascular and nervous systems display a high degree of cross-talk and depend on each other functionally. In the vascularization of the central nervous system, astrocytes have been thought to sense tissue oxygen levels in hypoxia-inducible factors (HIFs)-dependent manner and control the vascular growth into the hypoxic area by secreting VEGF. However, recent genetic evidences demonstrate that not only astrocyte HIFs but also astrocyte VEGF expression is dispensable for developmental angiogenesis of the retina. This study demonstrates that hypoxia-inducible factor 1 alpha subunit (HIF-1α), a key transcription factor involved in cellular responses to hypoxia, is most abundantly expressed in the neuroretina, especially retinal progenitor cells (RPCs). A neuroretina-specific knockout of HIF-1α (αCre+Hif1α flox/flox) showed impaired vascular development characterized by decreased tip cell filopodia and reduced vessel branching. The astrocyte network was hypoplastic in αCre+Hif1α flox/flox mice. Mechanistically, platelet-derived growth factor A (PDGF-A), a mitogen for astrocytes, was downregulated in the neuroretina of αCre+Hif1α flox/flox mice. Supplementing PDGF-A restored reduced astrocytic and vascular density in αCre+Hif1α flox/flox mice. Our data demonstrates that the neuroretina but not astrocytes acts as a primary oxygen sensor which ultimately controls the retinal vascular development by regulating an angiogenic astrocyte template