No abstract

A subset of patients with autoimmune diseases including rheumatoid arthritis (RA) and lupus appear to be exposed continually to interferon (IFN) as evidenced by elevated expression of IFN induced genes in blood cells. In lupus, detection of endogenous chromatin complexes by the innate sensing machinery is the suspected driver for the IFN, but the actual mechanisms remain unknown in all of these diseases. We investigated in two randomized clinical trials the effects on RA patients of baminercept, a lymphotoxin-beta receptor-immunoglobulin fusion protein that blocks the lymphotoxin-αβ/LIGHT axis. Administration of baminercept led to a reduced RNA IFN signature in the blood of patients with elevated baseline signatures. Both RA and SLE patients with a high IFN signature were lymphopenic and lymphocyte counts increased following baminercept treatment of RA patients. These data demonstrate a coupling between the lymphotoxin-LIGHT system and IFN production in rheumatoid arthritis. IFN induced retention of lymphocytes within lymphoid tissues is a likely component of the lymphopenia observed in many autoimmune diseases.ClinicalTrials.gov NCT00664716.

Assembly of the ocular anterior segment (AS) is a critical event during development of the vertebrate visual system. Failure in this process leads to anterior segment dysgenesis (ASD), which is characterized by congenital blindness and predisposition to glaucoma. The anterior segment is largely formed via a neural crest-derived population, the Periocular Mesenchyme (POM). In this study, we aimed to characterize POM behaviors and transcriptional identities during early establishment of the zebrafish AS. Two-color fluorescent in situ hybridization suggested that early AS associated POM comprise of a heterogenous population. In vivo and time-course imaging analysis of POM distribution and migratory dynamics analyzed using transgenic zebrafish embryos (Tg[foxc1b:GFP], Tg[foxd3:GFP], Tg[pitx2:GFP], Tg[lmx1b.1:GFP], and Tg[sox10:GFP]) revealed unique AS distribution and migratory behavior among the reporter lines. Based on fixed timepoint and real-time analysis of POM cell behavior a comprehensive model for colonization of the zebrafish AS was assembled. Furthermore, we generated single cell transcriptomic profiles (scRNA) from our POM reporter lines and characterized unique subpopulation expression patterns. Based on scRNA clustering analysis we observed cluster overlap between neural crest associated (sox10/foxd3), POM (pitx2) and finally AS specified cells (lmx1b, and foxc1b). scRNA clustering also revealed several novel markers potentially associated with AS development and/or function including lum, fmoda, adcyap1b, tgfbi, and hmng2. Taken together, our data indicates that AS-associated POM, or Anterior Segment Mesenchyme (ASM), is not homogeneous but rather comprised of several subpopulations with differing colonization patterns, migration behavior, and transcriptomic profiles.

Vertebrate retinal development requires timely and precise fusion of the optic fissure (OF). Failure of this event leads to congenital vision impairment in the form of coloboma. Recent studies have suggested hyaloid vasculature to be involved in OF fusion. In order to examine this link, we analyzed OF fusion and hyaloid vasculogenesis in the zebrafish pax2a noi mutant line. We first determined that pax2a −/− embryos fail to accumulate F-actin in the OF prior to basement membrane (BM) degradation. Furthermore, using 3D and live imaging we observed reduced OF hyaloid vascularization in pax2a −/− embryos. When examining the connection between pax2a loss of function and hyaloid vasculature, we observed significant reduction of talin1 expression, a regulator of hyaloid vasculature. In addition, cranial VEGF expression was found to be reduced in pax2a −/− embryos. Pharmacological inhibition of VEGF signaling phenocopied the pax2a −/− vasculature, F-actin and BM degradation phenotypes. Lastly, we determined that OF associated hyaloid vasculature is a source of mmp2, mmp14a and mmp14b expression and showed that mmp2 is functionally necessary for degradation of OF BM. Taken together we propose a pax2a driven mechanism that ensures proper and timely hyaloid vasculature invasion of the OF in order to facilitate availability of the BM remodeler mmp2. Ocular development is a highly conserved process amongst vertebrate species. Assembly of the hemispherical, retinal structure from an initially flat sheet of cells requires many complex morphogenetic movements. One such morphogenetic movement involves the invagination of the optic vesicle which results in a fissure forming at the ventral region of the developing retina. This fissure, known as the choroid or optic fissure (OF), enables hyaloid vasculature cell migration into the developing retina and subsequent establishment of the hyaloid vasculature. Hyaloid vasculature is a temporary circulatory system required for ocular development, and in most cases will degenerate once mature blood vessels begin to grow 1-4. As soon as the hyaloid vasculature has been established, the two opposing retinal epithelial sheets of the OF will undergo fusion. Thereby, they encase the ganglion cell axons localized in the optic stalk and complete retinal morphogenesis. Failure of OF fusion leads to a congenital blinding disorder known as coloboma 5-7. Coloboma is a prevalent cause of pediatric blindness, accounting for approximately 10% of cases worldwide 6,8. This makes it one of the leading causes of pediatric blindness. Coloboma is a spectrum disorder presenting unilaterally or bilaterally and ranging in severity from minor visual impairment, to complete blindness in the affected eye 9. This spectrum of severity is associated with the location and degree to which the OF was able to fuse and the severity of subsequent loss of ganglion cell axons 7. Coloboma has been studied for many decades in many different species. Work over this time has led to a general outline of the signaling and morphogen...

Establishment of the ocular anterior segment (AS) is a critical event during development of the vertebrate visual system. Failure in this process leads to Anterior Segment Dysgenesis (ASD), which is characterized by congenital blindness and predisposition to glaucoma. The anterior segment is largely formed via a neural crest-derived population, the Periocular Mesenchyme (POM). In this study, we aimed to characterize POM behaviors and identities during zebrafish AS development. POM distributions and migratory dynamics were analyzed using transgenic zebrafish embryos (Tg[foxC1b:GFP], Tg[foxD3:GFP], Tg[pitx2:GFP], Tg[lmx1b.1:GFP], and Tg[sox10:GFP] throughout the course of early AS development (24-72hpf). In vivo imaging analysis revealed unique AS distribution and migratory behavior among the reporter lines, suggesting AS mesenchyme (ASM) is a heterogenous population. This was confirmed using double in situ hybridization. Furthermore, we generated ASM transcriptomic profiles from our reporter lines and using a four-way comparison analysis uncovered unique ASM subpopulation expression patterns. Taken together, our data reveal for the first time that AS-associated POM is not homogeneous but rather comprised of several unique subpopulations identifiable by their distributions, behaviors, and transcriptomic profiles.