Inflammasome activation aggravates choroidal neovascularization.

Inflammasome activation is implicated in diseases of aberrant angiogenesis such as age-related macular degeneration (AMD), though its precise role in choroidal neovascularization (CNV), a characteristic pathology of advanced AMD, is ill-defined. Reports on inhibition of inflammasome constituents on CNV are variable and the precise role of inflammasome in mediating pathological angiogenesis is unclear. Historically, subretinal injection of inflammasome agonists alone has been used to investigate retinal pigmented epithelium (RPE) degeneration, while the laser photocoagulation model has been used to study pathological angiogenesis in a model of CNV. Here, we report that the simultaneous introduction of any of several disease-relevant inflammasome agonists (Alu or B2 RNA, Alu cDNA, or oligomerized amyloid ß (1-40)) exacerbates laser-induced CNV. These activities were diminished or abrogated by genetic or pharmacological targeting of inflammasome signaling constituents including P2rx7, Nlrp3, caspase-1, caspase-11, and Myd88, as well as in myeloid-specific caspase-1 knockout mice. Alu RNA treatment induced inflammasome activation in macrophages within the CNV lesion, and increased accumulation of macrophages in an inflammasome-dependent manner. Finally, IL-1ß neutralization prevented inflammasome agonist-induced chemotaxis, macrophage trafficking, and angiogenesis. Collectively, these observations support a model wherein inflammasome stimulation promotes and exacerbates CNV and may be a therapeutic target for diseases of angiogenesis such as neovascular AMD.

Efficient reduction of the scrolling of Descemet membrane endothelial keratoplasty grafts by engineering the medium.

The Descemet Membrane Endothelial Keratoplasty (DMEK) procedure for corneal transplantation is challenging due to the need to unscroll the donor graft within the recipient's eye. This process of unscrolling is complex, time-consuming, leads to a loss of endothelial cells and, most importantly, can negatively impact the graft's adhesion and integration with the host tissue after surgery. This problem is particularly evident when the graft is young. However, the physics behind this scrolling is not well understood, and therefore no sustainable solution is attained. Here, we propose that the concentration gradient of the medium used during transplant leads to a displacement gradient across the graft thickness, resulting in an out-of-plane folding or scrolling of the graft tissue. Using chitosan bilayer-based experimental models, it is experimentally demonstrated that this diffusion-coupled-deformation phenomenon can successfully explain why younger donor grafts tend to scroll tighter than older ones. Most importantly, we illustrate here through experiments that the medium can be engineered to reduce the scroll tightness and thus reduce the surgical inconveniences and improve post-transplant recovery. STATEMENT OF SIGNIFICANCE: This paper addresses a major issue that surgeons face while doing Descemet Membrane Endothelial Keratoplasty (DMEK) in unscrolling grafts during the graft insertion procedure. The currently used tapping method to unscroll the graft inside the patient's eye significantly reduces endothelial cell count, thus affecting its lifetime. Surprisingly, the physics behind graft scrolling is not well understood, so no sustainable solutions are proposed by the medical community. In this work, we present the underlying mechanism of DMEK graft scroll and illustrate experimentally the reason for scroll tightness through a chitosan bilayer based experiment model. Most importantly, we have successfully demonstrated that the preserving medium of the grafts can be engineered to reduce scroll tightness.

Retinoblastoma: A review of the molecular basis of tumor development and its clinical correlation in shaping future targeted treatment strategies.

Retinoblastoma is a retinal cancer that affects children and is the most prevalent intraocular tumor worldwide. Despite tremendous breakthroughs in our understanding of the fundamental mechanisms that regulate progression of retinoblastoma, the development of targeted therapeutics for retinoblastoma has lagged. Our review highlights the current developments in the genetic, epigenetic, transcriptomic, and proteomic landscapes of retinoblastoma. We also discuss their clinical relevance and potential implications for future therapeutic development, with the aim to create a frontline multimodal therapy for retinoblastoma.

A goat eye, wet lab model for training in Descemet membrane endothelial keratoplasty.

Here we describe a new, non-human, ex-vivo model (goat eye model) for training surgeons in DMEK surgeons. In a wet lab setting, goat eyes were used to obtain a pseudo-DMEK graft of 8 mm from the goat lens capsule that was injected into another goat eye with the same maneuvers described for human DMEK. The DMEK pseudo-graft can be easily prepared, stained, loaded, injected, and unfolded into the goat eye model reproducing the similar maneuvers used for DMEK in a human eye, except for the descemetorhexis, which cannot be performed. The pseudo-DMEK graft behaves similar to human DMEK graft and useful for surgeons to experience and understand steps of DMEK early in learning curve. The concept of a non-human ex-vivo eye model is simple and reproducible and obviates the need for human tissue and the issues of poor visibility in stored corneal tissue.

Role of AS-OCT in Managing Corneal Disorders.

Optical coherence tomography (OCT) is analogous to ultrasound biometry in the cross sectional imaging of ocular tissues. Development of current devices with deeper penetration and higher resolution has made it popular tool in clinics for visualization of anterior segment structures. In this review, the authors discussed the application of AS-OCT for diagnosis and management of various corneal and ocular surface disorders. Further, recent developments in the application of the device for pediatric corneal disorders and extending the application of OCT angiography for anterior segment are introduced.

MSH3 Homology and Potential Recombination Link to SARS-CoV-2 Furin Cleavage Site.

Among numerous point mutation differences between the SARS-CoV-2 and the bat RaTG13 coronavirus, only the 12-nucleotide furin cleavage site (FCS) exceeds 3 nucleotides. A BLAST search revealed that a 19 nucleotide portion of the SARS.Cov2 genome encompassing the furing cleavage site is a 100% complementary match to a codon-optimized proprietary sequence that is the reverse complement of the human mutS homolog (MSH3). The reverse complement sequence present in SARS-CoV-2 may occur randomly but other possibilities must be considered. Recombination in an intermediate host is an unlikely explanation. Single stranded RNA viruses such as SARS-CoV-2 utilize negative strand RNA templates in infected cells, which might lead through copy choice recombination with a negative sense SARS-CoV-2 RNA to the integration of the MSH3 negative strand, including the FCS, into the viral genome. In any case, the presence of the 19-nucleotide long RNA sequence including the FCS with 100% identity to the reverse complement of the MSH3 mRNA is highly unusual and requires further investigations.

DDX17 is an essential mediator of sterile NLRC4 inflammasome activation by retrotransposon RNAs.

Detection of microbial products by multiprotein complexes known as inflammasomes is pivotal to host defense against pathogens. Nucleotide-binding domain leucine-rich repeat (NLR) CARD domain containing 4 (NLRC4) forms an inflammasome in response to bacterial products; this requires their detection by NLR family apoptosis inhibitory proteins (NAIPs), with which NLRC4 physically associates. However, the mechanisms underlying sterile NLRC4 inflammasome activation, which is implicated in chronic noninfectious diseases, remain unknown. Here, we report that endogenous short interspersed nuclear element (SINE) RNAs, which promote atrophic macular degeneration (AMD) and systemic lupus erythematosus (SLE), induce NLRC4 inflammasome activation independent of NAIPs. We identify DDX17, a DExD/H box RNA helicase, as the sensor of SINE RNAs that licenses assembly of an inflammasome comprising NLRC4, NLR pyrin domain­containing protein 3, and apoptosis-associated speck-like protein­containing CARD and induces caspase-1 activation and cytokine release. Inhibiting DDX17-mediated NLRC4 inflammasome activation decreased interleukin-18 release in peripheral blood mononuclear cells of patients with SLE and prevented retinal degeneration in an animal model of AMD. Our findings uncover a previously unrecognized noncanonical NLRC4 inflammasome activated by endogenous retrotransposons and provide potential therapeutic targets for SINE RNA­driven diseases.

Infectious Keratitis: An Update on Role of Epigenetics.

Epigenetic mechanisms modulate gene expression and function without altering the base sequence of DNA. These reversible, heritable, and environment-influenced mechanisms generate various cell types during development and orchestrate the cellular responses to external stimuli by regulating the expression of genome. Also, the epigenetic modifications influence common pathological and physiological responses including inflammation, ischemia, neoplasia, aging and neurodegeneration etc. In recent past, the field of epigenetics has gained momentum and become an increasingly important area of biomedical research As far as eye is concerned, epigenetic mechanisms may play an important role in many complex diseases such as corneal dystrophy, cataract, glaucoma, diabetic retinopathy, ocular neoplasia, uveitis, and age-related macular degeneration. Focusing on the epigenetic mechanisms in ocular diseases may provide new understanding and insights into the pathogenesis of complex eye diseases and thus can aid in the development of novel treatments for these diseases. In the present review, we summarize the clinical perspective of infectious keratitis, role of epigenetics in infectious keratitis, therapeutic potential of epigenetic modifiers and the future perspective.

Identification of fluoxetine as a direct NLRP3 inhibitor to treat atrophic macular degeneration.

The atrophic form of age-related macular degeneration (dry AMD) affects nearly 200 million people worldwide. There is no Food and Drug Administration (FDA)-approved therapy for this disease, which is the leading cause of irreversible blindness among people over 50 y of age. Vision loss in dry AMD results from degeneration of the retinal pigmented epithelium (RPE). RPE cell death is driven in part by accumulation of Alu RNAs, which are noncoding transcripts of a human retrotransposon. Alu RNA induces RPE degeneration by activating the NLRP3-ASC inflammasome. We report that fluoxetine, an FDA-approved drug for treating clinical depression, binds NLRP3 in silico, in vitro, and in vivo and inhibits activation of the NLRP3-ASC inflammasome and inflammatory cytokine release in RPE cells and macrophages, two critical cell types in dry AMD. We also demonstrate that fluoxetine, unlike several other antidepressant drugs, reduces Alu RNA-induced RPE degeneration in mice. Finally, by analyzing two health insurance databases comprising more than 100 million Americans, we report a reduced hazard of developing dry AMD among patients with depression who were treated with fluoxetine. Collectively, these studies identify fluoxetine as a potential drug-repurposing candidate for dry AMD.