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Research Square Jun 2024Background - Glaucoma is a complex multifactorial disease where apoptosis and inflammation represent two key pathogenic mechanisms. However, the relative contribution of...
Background - Glaucoma is a complex multifactorial disease where apoptosis and inflammation represent two key pathogenic mechanisms. However, the relative contribution of apoptosis versus inflammation in axon degeneration and death of retinal ganglion cells (RGCs) is not well understood. In glaucoma, caspase-8 is linked to RGC apoptosis, as well as glial activation and neuroinflammation. To uncouple these two pathways and determine the extent to which caspase-8-mediated inflammation and/or apoptosis contributes to the death of RGCs, we used the caspase-8 D387A mutant mouse ( ) in which a point mutation in the auto-cleavage site blocks caspase-8-mediated apoptosis but does not block caspase-8-mediated inflammation. Methods- Intracameral injection of magnetic microbeads was used to elevate the intraocular pressure (IOP) in wild-type, Fas deficient Fas , and mice. IOP was monitored by rebound tonometry. Two weeks post microbead injection, retinas were collected for microglia activation analysis. Five weeks post microbead injection, visual acuity and RGC function were assessed by optometer reflex (OMR) and pattern electroretinogram (pERG), respectively. Retina and optic nerves were processed for RGC and axon quantification. Two- and five-weeks post microbead injection, expression of the necrosis marker, RIPK3, was assessed by qPCR. Results- Wild-type, Fas , and mice showed similar IOP elevation as compared to saline controls. A significant reduction in both visual acuity and pERG that correlated with a significant loss of RGCs and axons was observed in wild-type but not in Fas mice. The mice displayed a significant reduction in visual acuity and pERG amplitude and loss of RGCs and axons similar to that in wild-type mice. Immunostaining revealed equal numbers of activated microglia, double positive for P2ry12 and IB4, in the retinas from microbead-injected wild-type and mutant mice. qPCR analysis revealed no induction of RIPK3 in wild-type or mice at two- or five-weeks post microbead injection. Conclusions- Our results demonstrate that caspase-8-mediated extrinsic apoptosis is not involved in the death of RGCs in the microbead-induced mouse model of glaucoma implicating caspase-8-mediated inflammation, but not apoptosis, as the driving force in glaucoma progression. Taken together, these results identify the caspase-8-mediated inflammatory pathway as a potential target for neuroprotection in glaucoma.
PubMed: 38947028
DOI: 10.21203/rs.3.rs-4409426/v1 -
Research Square Jun 2024Melanoma-associated retinopathy (MAR) is a paraneoplastic syndrome associated with cutaneous metastatic melanoma in which patients develop vision deficits that include...
Melanoma-associated retinopathy (MAR) is a paraneoplastic syndrome associated with cutaneous metastatic melanoma in which patients develop vision deficits that include reduced night vision, poor contrast sensitivity, and photopsia. MAR is caused by autoantibodies targeting TRPM1, an ion channel found in melanocytes and retinal ON-bipolar cells (ON-BCs). The visual symptoms arise when TRPM1 autoantibodies enter ON-BCs and block the function of TRPM1, thus detection of TRPM1 autoantibodies in patient serum is a key criterion in diagnosing MAR. Electroretinograms are used to measure the impact of TRPM1 autoantibodies on ON-BC function and represent another important diagnostic tool for MAR. To date, MAR case reports have included one or both diagnostic components, but only for a single time point in the course of a patient's disease. Here, we report a case of MAR supported by longitudinal analysis of serum autoantibody detection, visual function, ocular inflammation, vascular integrity, and response to slow-release intraocular corticosteroids. Integrating these data with the patient's oncological and ophthalmological records reveals novel insights regarding MAR pathogenesis, progression, and treatment, which may inform new research and expand our collective understanding of the disease. In brief, we find TRPM1 autoantibodies can disrupt vision even when serum levels are barely detectable by western blot and immunohistochemistry; intraocular dexamethasone treatment alleviates MAR visual symptoms despite high levels of circulating TRPM1 autoantibodies, implicating antibody access to the retina as a key factor in MAR pathogenesis. Elevated inflammatory cytokine levels in the patient's eyes may be responsible for the observed damage to the blood-retinal barrier and subsequent entry of autoantibodies into the retina.
PubMed: 38946992
DOI: 10.21203/rs.3.rs-4595829/v1 -
Proceedings. International Conference... Oct 2023The Ultra-Wide-Field (UWF) retina images have attracted wide attentions in recent years in the study of retina. However, accurate registration between the UWF images and...
The Ultra-Wide-Field (UWF) retina images have attracted wide attentions in recent years in the study of retina. However, accurate registration between the UWF images and the other types of retina images could be challenging due to the distortion in the peripheral areas of an UWF image, which a 2D warping can not handle. In this paper, we propose a novel 3D distortion correction method which sets up a 3D projection model and optimizes a dense 3D retina mesh to correct the distortion in the UWF image. The corrected UWF image can then be accurately aligned to the target image using 2D alignment methods. The experimental results show that our proposed method outperforms the state-of-the-art method by 30%.
PubMed: 38946915
DOI: 10.1109/icip49359.2023.10223163 -
Journal of Materials Chemistry. B Jul 2024Topical treatment of vitreoretinal diseases remains a challenge due to slow corneal uptake and systemic clearance. Exosomes are emerging nanocarriers for drug delivery...
Topical treatment of vitreoretinal diseases remains a challenge due to slow corneal uptake and systemic clearance. Exosomes are emerging nanocarriers for drug delivery due to biocompatibility and cellular targeting properties. To apply them for retinal targeting the topical route, exosomes must traverse various ocular barriers including the cornea, lens, vitreous humor (VH), and the retina itself. Here we engineered high-purity milk-derived exosomes by anchoring arginine-rich cationic motifs PEG lipid insertion on their surface. Modification enabled exosomes to use weak-reversible electrostatic interactions with anionic glycosaminoglycan (GAG) and water content of the tissue to enhance their transport rate and retention. Addition of cationic motifs neutralized the anionic surface charge of exosomes (-24 to -2 mV) without impacting size or morphology. Cationic-motif-modified exosomes exhibited two-fold faster steady state diffusivity through bovine corneas compared to unmodified exosomes. Fluorescence recovery after photobleaching confirmed that cationic-motif-modified exosomes can diffuse through VH without steric hindrance. In healthy VH, cationic-motif-modified exosomes demonstrated stronger binding resulting in three-fold lower average diffusivity that enhanced by six-fold in 50% GAG-depleted VH recapitulating advanced liquefaction. Cationic-motif-modified exosomes penetrated through the full-thickness of porcine retinal explants resulting in ten-fold higher uptake in photoreceptors and three-fold greater transfection with encapsulated eGFP mRNA compared to unmodified exosomes. Cationic-motif-modified exosomes are safe to use as they did not adversely affect the mechanical swelling properties of the cornea or lens nor impact retinal cell viability. Cationic-motif-modified exosomes, therefore, offer themselves as a cell-free nanocarrier platform for gene delivery to retinal photoreceptors potentially the topical route.
PubMed: 38946491
DOI: 10.1039/d4tb00849a -
Journal of Neuro-ophthalmology : the... Jul 2024Although cupping of the optic nerve is classically a sign of glaucomatous optic neuropathy, it has been shown that cupping can sometimes occur after an episode of optic...
Optic Disc Cupping in Neuromyelitis Optica Spectrum Disorder, Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease, and Multiple Sclerosis and Its Relationship With Optical Coherence Tomography Parameters: A Multicenter Study.
BACKGROUND
Although cupping of the optic nerve is classically a sign of glaucomatous optic neuropathy, it has been shown that cupping can sometimes occur after an episode of optic neuritis (ON). The purpose of this study was to compare cupping in patients after ON from multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and to investigate the relationship between cupping and retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thinning.
METHODS
This was a retrospective cohort involving patients (≥18 years) with ON from 3 institutions. Patients were eligible if they had optical coherence tomography (Cirrus, OCT) performed ≥6 months after a single unilateral ON. The amount of thinning and cupping was estimated from the difference in the OCT parameters between affected and unaffected eyes. Univariable and multivariable regressions were used to investigate the relationship between cupping and ON etiology. Pearson correlation was used to investigate the relationship between cupping and RNFL and GCC.
RESULTS
Eighty-six subjects (MS: 35, NMOSD: 26, and MOGAD: 25) were included. There was no significant difference in gender and race between the groups, and most patients (86.1%) were female. Patients with NMOSD were significantly older than patients with MS or MOGAD (P = 0.002). In the univariate model, cupping was significantly higher in the NMOSD group (P = 0.017); however, after adjusting for age, GCC, and RNFL of the affected eye, the difference was no longer statistically significant (P = 0.949). The correlation between cupping asymmetry and RNFL and GCC of the affected eye was inversely strong in patients with MS (R = -0.60 and R = -0.64, respectively), inversely moderate in patients with MOGAD (R = -0.34 and R = -0.40, respectively), and weak in patients with NMOSD (R = -0.03 and R = -0.17, respectively).
CONCLUSIONS
Our results demonstrated that cupping after ON is correlated with RNFL and GCC thinning; although cupping was overall greater in the NMOSD group, once adjusted for age, RNFL, and GCC, it did not differ among patients with MS, NMOSD, and MOGAD.
PubMed: 38946028
DOI: 10.1097/WNO.0000000000002204 -
Experimental Eye Research Jun 2024Ocular complications of diabetes mellitus (DM) are the leading cause of vision loss. Ocular inflammation often occurs in the early stage of DM; however, there are no...
Ocular complications of diabetes mellitus (DM) are the leading cause of vision loss. Ocular inflammation often occurs in the early stage of DM; however, there are no proven quantitative methods to evaluate the inflammatory status of eyes in DM. The 18 kDa translocator protein (TSPO) is an evolutionarily conserved cholesterol binding protein localized in the outer mitochondrial membrane. It is a biomarker of activated microglia/macrophages; however, its role in ocular inflammation is unclear. In this study, fluorine-18-DPA-714 ([F]-DPA-714) was evaluated as a specific TSPO probe by cell uptake, cell binding assays and micro positron emission tomography (microPET) imaging in both in vitro and in vivo models. Primary microglia/macrophages (PMs) extracted from the cornea, retina, choroid or sclera of neonatal rats with or without high glucose (50 mM) treatment were used as the in vitro model. Sprague-Dawley (SD) rats that received an intraperitoneal administration of streptozotocin (STZ, 60 mg/kg once) were used as the in vivo model. Increased cell uptake and high binding affinity of [F]-DPA-714 were observed in primary PMs under hyperglycemic stress. These findings were consistent with cellular morphological changes, cell activation, and TSPO up-regulation. [F]-DPA-714 PET imaging and biodistribution in the eyes of DM rats revealed that inflammation initiates in microglia/macrophages in the early stages (3 weeks and 6 weeks), corresponding with up-regulated TSPO levels. Thus, [F]-DPA-714 microPET imaging may be an effective approach for the early evaluation of ocular inflammation in DM.
PubMed: 38945519
DOI: 10.1016/j.exer.2024.109986 -
Experimental Eye Research Jun 2024Aging is a major risk factor for the development or the worsening of retinal degenerative conditions. The intricate network of the neural retina determined that the...
Aging is a major risk factor for the development or the worsening of retinal degenerative conditions. The intricate network of the neural retina determined that the retinal aging is a complicated process. The aim of this study is to delineate the transcriptomic changes of major retinal neurons during aging in C57BL/6 mice at single-cell level. We analyzed the transcriptional profiles of the photoreceptor, bipolar, amacrine, and Müller glial cells of 1.5-2 and 24-30 months old mice using single-cell RNA sequencing technique. We selectively confirmed the differences in gene expression using immunofluorescence staining and RNA in situ hybridization analysis. We found that each retinal cell type had unique changes upon aging. However, they all showed signs of dysregulated glucose and energy metabolism, and perturbed proteostasis. In particular, old Müller glia exhibited the most profound changes, including the upregulation of cell metabolism, stress-responses, antigen-presentation and immune responses and metal ion homeostasis. The dysregulated gliogenesis and differentiation was confirmed by the presence of Müller glia expressing rod-specific genes in the inner nuclear layer and the outer plexiform layer of the old retina. We further pinpointed the specific loss of GABAergic amacrine cells in old retina. Our study emphasized changes of amacrine and Müller glia during retinal aging, provided resources for further research on the molecular and cellular regulatory mechanisms underlying aging-associated retinal deterioration.
PubMed: 38945518
DOI: 10.1016/j.exer.2024.109985 -
Experimental Eye Research Jun 2024Aging changes the responsiveness of our immune defense, and this decline in immune reactivity plays an important role in the increased susceptibility to infections that...
Aging changes the responsiveness of our immune defense, and this decline in immune reactivity plays an important role in the increased susceptibility to infections that marks progressing age. Aging is also the most pronounced risk factor for development of age-related macular degeneration (AMD), a disease that is characterized by dysfunctional retinal pigment epithelial (RPE) cells and loss of central vision. We have previously shown that acute systemic viral infection has a large impact on the retina in young mice, leading to upregulation of chemokines in the RPE/choroid (RPE/c) and influx of CD8 T cells in the neuroretina. In this study, we sought to investigate the impact of systemic infection on the RPE/c in aged mice to evaluate whether infection in old age could play a role in the pathogenesis of AMD. We found that systemic infection in mice led to upregulation of genes from the crystallin family in the RPE/c from aged mice, but not in the RPE/c from young mice. Crystallin alpha A (CRYAA) was the most upregulated gene, and increased amounts of CRYAA protein were also detected in the aged RPE/c. Increased CRYAA gene and protein expression has previously been found in drusen and choroid from AMD patients, and this protein has also been linked to neovascularization. Since both drusen and neovascularization are important hallmarks of advanced AMD, it is interesting to speculate if upregulation of crystallins in response to infection in old age could be relevant for the pathogenesis of AMD.
PubMed: 38945517
DOI: 10.1016/j.exer.2024.109984 -
Journal of Stroke and Cerebrovascular... Jun 2024transient ischemic attack (TIA) is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, with clinical...
PURPOSE
transient ischemic attack (TIA) is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, with clinical symptoms typically lasting less than one hour, and without evidence of acute infarction. In this type of ischemic event, there are no data about a possible cardiac injury tested with troponin. After a stroke, it is well established the cardiac involvement due to a neuro-inflammatory response (recently defined as Stroke Heart Syndrome). The aim of this study is to compare the troponin elevation after a stroke with TIA.
MATERIALS AND METHODS
this is a retrospective, single center study on 565 patients (73 TIAs, 492 stroke). We collected demographic characteristics, cardiovascular risk factors, cardiac data such as troponin, NT-proBNP, left atrial dilatation, etiology of the ischemic event (TOAST classification).
RESULTS
we compare IS and TIA for each TOAST subtype. In all groups no substantial differences were found in demographic and past medical history (p>0.05). However, the maximum troponin level reached were significantly lower in TIAs than IS (p<0.05), except in lacunar etiology were troponin elevation was low also in IS group. We found a trend in favor to IS in the rise and fall troponin elevation over 30% in all the TOAST subgroups, but only in the cryptogenic etiology the difference was significant. About the others cardiac markers of injury, a significant higher rate of elevated NT-proBNP was found in the IS cohort.
CONCLUSIONS
troponin level after TIAs is significantly lower than after IS. Troponin elevation after an ischemic event may be more relevant in patients with higher NT-proBNP levels and older age. More studies are needed to better understand the patho-physiology of this phenomenon after an ischemic event.
PubMed: 38945415
DOI: 10.1016/j.jstrokecerebrovasdis.2024.107844 -
Mucosal Immunology Jun 2024Intestinal stromal cells (SCs), which synthesize the extracellular matrix that gives the mucosa its structure, are newly appreciated to play a role in mucosal...
Intestinal stromal cells (SCs), which synthesize the extracellular matrix that gives the mucosa its structure, are newly appreciated to play a role in mucosal inflammation. Here we show that human intestinal vimentinCD90SMA SCs synthesize retinoic acid (RA) at levels equivalent to intestinal epithelial cells, a function in the human intestine previously attributed exclusively to epithelial cells. Crohn's disease SCs (Crohn's SCs), however, synthesized markedly less RA than SCs from healthy intestine (Normal SCs). We also show that microbe-stimulated Crohn's SCs, which are more inflammatory than stimulated Normal SCs, induced less RA-regulated differentiation of mucosal DCS (circulating pre-DCs and monocyte-derived DCs), leading to the generation of more potent inflammatory IFN-γ/IL-17 T cells than Normal SCs. Explaining these results, Crohn's SCs expressed more DHRS3, a retinaldehyde reductase that inhibits retinol conversion to retinal, and thus synthesized less RA than Normal SCs. These findings uncover a microbe-SC-DC crosstalk in which luminal microbes induce Crohn's disease SCs to initiate and perpetuate inflammation through impaired synthesis of RA.
PubMed: 38945396
DOI: 10.1016/j.mucimm.2024.06.009