Background The critical role for chronic inflammation in the development of thoracic aortic aneurysms and dissections (TAADs) has been recognized in both experimental and clinical settings. However, challenges remain on translating this knowledge to clinical applications. In this study, we tested the hypothesis that TLR-7 signaling triggered by self-RNAs substantiates chronic inflammation, promoting TAAD formation. Methods A mouse TAAD model induced by SMC-specific deletion of Tgfbr1 (Tgfbr1iko) was used. Results In this model, the expression of TLR-7 was progressively upregulated during the early stages, resulting in a two-fold differential at 2 weeks compared with control aortas (P = .003). RNAScope assays showed that cells located in the media and adventitia were responsible for the upregulation. Additionally, immunofluorescence staining showed that TLR-7 is induced in human TAADs. Treatment with hydroxychloroquine, which inhibits TLR-7 receptor function, significantly decreased the number of intimal and medial tears (P = .026) and mitigated intramural hemorrhage (P = .007) compared with vehicle controls (n = 7/group). Further assays with bone marrow derived dendritic cells demonstrated that RNAs, particularly small RNAs, extracted from TAADs induced significantly higher interferon α/β levels compared with normal aortas (P = .025). Similarly, RNAs extracted from Tgfbr1iko SMCs induced higher levels of interferon α, IP-10, and MCP1 compared with those harvested from wild-type smooth muscle cells. Necroptosis (labeled with RIPK3 and pMLKL) and RNA oxidation (labeled with 8-OHG) were evident in the media of TAADs, and might serve as the source for the endogenous TLR-7 ligand. Finally, treatment with the TLR-7 specific inhibitor, M5049, at a dose of 1.0 or 5.0 mg/kg/day via oral gavage prevented dilation of TAADs at four weeks compared with vehicle controls (9% vs 8% vs 23%; P < .001). Conclusions Self-RNAs released from stressed and dying cells is associated with chronically inflamed aortic tissue and promotes TAAD development via triggering TLR-7 signaling. Blocking TLR-7 signaling may represent a novel strategy to treat human TAADs.

Background: Regulatory T cells (Tregs) suppress inflammation in atherosclerosis, and therefore have the therapeutic potential to decrease the risk of myocardial infarction and stroke. However, there is currently no method to generate antigen specific Tregs that target atherosclerosis. We therefore engineered Tregs that express a chimeric antigen receptor (CAR) targeting malonaldehyde-modified low-density lipoprotein cholesterol (MDA-LDL), the most common form of oxidized LDL and a key molecular component of atherosclerosis. Methods: Novel single chain variable fragments (scFv) were synthesized using sequences from antibodies targeting human MDA-LDL. OxidizedLDL specific CARs (ox-CARs) were subsequently engineered by fusing each scFv to an IgG4 hinge, CD28 transmembrane, and CD28/CD3z cytoplasmic domains. CD4+ CD25+ CD127low/e Tregs were purified from human blood via fluorescent activated cell sorting and lentivirally transduced to express the novel ox-CARs (ox-CAR-Tregs). Human atherosclerotic plaques were obtained from patients undergoing carotid endarterectomy. Autologous ox-CAR-Tregs were analyzed for activation after ex vivo coculture with carotid endarterectomy samples. Results: A rationally designed panel of 42 ox-CARs were engineered using scFv derived from 12 antibodies targeting MDA-LDL. We first assessed CAR expression and activation in Jurkat T cells to identify promising oxCAR variants for further evaluation in human Tregs. After culture in the presence of MDA-LDL, six ox-CAR-Treg variants consistently showed significant activation, compared with controls, based on CD71 expression, cytokine expression, and proliferation in the absence of CD3/28 stimulation. Human atherosclerotic samples were identified to have substantial amounts of MDA-LDL epitopes using immunohistochemistry. Autologous ox-CAR-Tregs showed a dose-dependent increase in CD71 expression after ex vivo co-culture with atherosclerotic plaque. Conclusions: An optimized CAR targeting MDA-LDL activates Tregs Q10 when cultured with human atherosclerotic plaque ex vivo.

Cytauxzoon felis is a tick-borne piroplasmid hemoparasite that causes life-threatening disease in cats. Despite the critical role that ticks play in disease transmission and development, our knowledge regarding the C. felis life cycle remains limited to the feline hosts and no stage of the parasite has been identified or investigated in ticks. Sporozoites are the infectious stage of piroplasmids that are transmitted by ticks. In other tick-borne piroplasmids, sporozoites have played a key role in disease prevention and management. We believe sporozoites have similar potential for cytauxzoonosis. Therefore, the objective of this study is to evaluate different molecular and microscopic techniques to detect C. felis sporozoites in tick salivary glands (SG). A total of 140 Amblyomma americanum ticks that were fed on C. felis-infected cats as nymphs were included for this study. Specifically, dissected SGs were quartered and subjected to C. felis RT-PCR, RNAscope in situ hybridization (ISH), histology, direct azure staining, and transmission electron microscopy (TEM). Cytauxzoon felis RT-PCR was also performed on half tick (HT) carcasses after SG dissection. Cytauxzoon felis RNA was detected in SGs of 17 ticks. Of these, 7 ticks had microscopic visualization via ISH and/or TEM. The remaining 10 ticks had only molecular detection of C. felis in SGs via RT-PCR without visualization. Cytauxzoon felis RNA was detected solely in HT carcasses via RT-PCR in 9 additional ticks. In ISH-positive tick SGs, hybridization signals were present in cytoplasms of SG acinar cells. TEM captured rare C. felis organisms with characteristic ultrastructural features of piroplasmid parasites. This study describes the first direct visualization of any developing stage of C. felis in ticks. Forthcoming studies should employ a combination of molecular and microscopic techniques to investigate the C. felis life cycle in A. americanum.

RESULTS : Uniform Manifold Approximation and Projection clustering identified distinct expression signatures from the ganglion cell layer(GCL), inner nuclear layer(INL), retinal pigment epithelium (RPE)/choroid/sclera, optic nerve, and ciliary body (Fig, 1) but not the outer nuclear layer(ONL) which was contaminated with expression from other layers. Our findings highlight Clu, C4b, Apoe, and C1qa genes (z-score 3.0, 2.4, 2.3, and 2.2) as potential markers of disease in the RPE. Gene Set Enrichment analysis between rd6 and WT eyes showed upregulation of glycolysis and carbon metabolism pathways in the GCL and Rap1, Hippo and lysosome pathways in the RPE/Choroid/sclera. The ribosomal pathway was downregulated in these layers. No significant pathways were found in the INL, ciliary body or optic nerve.

RESULTS : After quality control and data integration, 17,401 nuclei were isolated from 26,471 original droplets, derived from macular samples of 4 patients without retinal disease and 3 patients with POAG. The proportion of retinal ganglion cells in glaucomatous retina was significantly lower than that in healthy retina (p=0.024). An activated subpopulation of Müller glia was identified in both healthy and glaucomatous retina by cell clustering. Cross-species analysis comparing zebrafish and humans identified YAP1 activation as a differentiator between zebrafish and human glial activation. Human retinal explants cultured with N3B1P3C demonstrated significant proliferation of GS+ Muller cells (p=0.044).

* Alfredo Dueñas Rey Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Víctor López-Soriano Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Zelia Corradi Radboudumc Department of Human Genetics, Nijmegen, Gelderland, Netherlands * Claire-Marie Dhaenens Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, Lille, France * Manon Bouckaert Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Jasper Verwilt Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium OncoRNALab, Cancer Research Institute Ghent, Ghent, Belgium * Avril M Watson Newcastle University Faculty of Medical Sciences, Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom * Majlinda Lako Newcastle University Faculty of Medical Sciences, Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom * Eva D’haene Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Karla Alejandra Ruiz Ceja Telethon Institute of Genetics and Medicine, Napoli, Campania, Italy * Sandro Banfi Telethon Institute of Genetics and Medicine, Napoli, Campania, Italy * Miriam Bauwens Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Frans P Cremers Radboudumc Department of Human Genetics, Nijmegen, Gelderland, Netherlands * Steve Lefever Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Elfride De Baere Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium * Frauke Coppieters Universitair Ziekenhuis Gent Centrum Medische Genetica Gent, Gent, Belgium Department of Biomolecular Medicine, Universiteit Gent Faculteit Geneeskunde en Gezondheidswetenschappen, Gent, Belgium

METHODS : Retinal, optic nerve head (ONH) and distal optic nerve (ON) tissues from 8 juvenile 10-12 week-old cats (4 males and 4 females) with feline congenital glaucoma (FCG) and 5 age-matched normal control cats (3 males and 2 females) were used. Data for weekly intraocular pressure (IOP) and optic nerve axon counts were available for all subjects. Protein and gene expression in tissue cryosections were examined by immunofluorescence labeling (IF) and RNAscope in situ hybridization (ISH), respectively. Retinal tissue was IF labeled for myeloid cell marker, IBA-1 and flat-mounted. ISH for markers of infiltrating monocytes/macrophages (_CCR2_) and proinflammatory cytokines (_IL1A_, _C1QA_, _TNF_) was performed. Microglia were identified by IF of homeostatic microglial marker, P2RY12. Microscopy images wereanalyzed using Image J, QuPath and Imaris. Two-tailed unpaired t-test or Mann-Whitney test or ANOVA were used for between-group comparisons (p

RESULTS : All 4 Wnt ligands, 4 Wnt inhibitors, and Fzd7 were preferentially expressed in the basal layer of the cornea and limbus compared to the suprabasal layer (_P_

RESULTS : Short-term lineage tracing data showed that _Lrig1_, _Lgr6_ and _Axin2_ label basal cells in MG ducts and acini. Long-term lineage tracing results showed that clones of labeled cells persist through multiple rounds of ductal and acinar renewal and give rise to differentiated progeny, identifying _Lrig1_+, _Lgr6_+ and _Axin2+_ ductal and acinar basal cells as self-renewing SCs. Forced expression of GLI2ΔN enhanced basal proliferation, caused expansion of _Lrig1_+ SCs, and lead to replacement of lipid-filled meibocytes by proliferative and poorly differentiated acinar cells. Transcriptional profiling of GLI2ΔN-expressing and control MGs revealed that forced GLI2ΔN expression caused greatly increased expression of _Lrig1_ and _Lgr6_ and suppressed expression of meibocyte differentiation genes.

PURPOSE : Methylenetetrahydrofolate reductase (_MTHFR_) is a critical enzyme in the folate/methionine/homocysteine pathway. Variants in _MTHFR, _notably _677C>T,_ have_ _been associated with glaucoma as well as Alzheimer’s disease and vascular dementia, suggesting an overlapping mechanism in brain and eye. However, mechanisms driving increased risk are not known, hindering the development of new treatments. Approximately 30% of individuals carry at least one copy of _MTHFR677C>T_, causing a 50% decrease in MTHFR enzyme efficiency. Reduced efficiency can lead to high levels of homocysteine in blood, resulting in vascular inflammation and increased risk for vascular damage. We hypothesize that vascular-specific expression of _MTHFR677C>T_ drives damaging effects in the retinal vasculature, priming the environment for additional risk.

RESULTS : PR-specific expression of _PRLΔE1_ was observed in the following canine models of progressive inherited retinal degeneration (IRD): _RPGR_-XLPRA1 and _NPHP5_-LCA. In _RPGR_-XLPRA2 carrier retinas that undergo random X-inactivation, patches of_ PRLΔE1 _expression correlated with patches of PR degeneration. However, we did not observe expression of _PRLΔE1_ 24 hrs and 2 wks after light exposure that triggers acute rod loss in the canine RHO-T4R model of adRP. No _PRLΔE1 _expression was seen either in the _CNGB3_-ACHM3 retina that undergoes extremely slow cone degeneration. In _RPGR-_XLPRA1 and _RPGR-_XLPRA2 dogs subretinally-injected with an AAV-_RPGR_ vector, _PRLΔE1 _was completely absent in treated PRs while robust expression was seen in diseased/untreated areas.

METHODS : 8-week wild-type mice were used to determine gene (_Htr1b_) expression. RNAscope _in situ_ hybridization (ISH) was performed on retinal cryosections and imaged using confocal microscopy. Whole field flash electroretinograms (ERGs) were used to record scotopic and photopic amplitudes in 22 mice (8 _Htr1b_-/-; 8 _Htr1b_+/-; 6 WT). Positive scotopic threshold response (pSTR), b-wave, and a-wave amplitudes were recorded. Visual behavior was evaluated in _Htr1b_-/- mice and controls by assessing the scotopic and photopic optokinetic response. Gratings of variable spatial frequency or contrast were presented to evaluate spatial frequency threshold and contrast sensitivity threshold, respectively. We performed retinal histology and _in vivo_ SD-OCT imaging on 8-week _Htr1b_-/- animals to quantify retinal layer thickness. Retinal layers (GCL, IPL, INL, OPL, and ONL) were measured as a percentage of total retinal thickness and compared to age and sex-matched wild-type controls.RGC numbers were determined from whole-mount retinas which were prepared and visualized with confocal microscopy. RBPMS-positive cells were counted semi-automatically using an ImageJ extension. Total cell density was normalized to image size.