SARS-CoV-2 Infection Causes Heightened Disease Severity and Mortality in a Mouse Model of Down Syndrome.

Recent epidemiological studies suggest that individuals with Down syndrome are more susceptible to SARS-CoV-2 infection and have higher rates of hospitalization and mortality than the general population. However, the main drivers behind these disparate health outcomes remain unknown. Herein, we performed experimental infections with SARS-CoV-2 in a well-established mouse model of Down syndrome. We observed similar SARS-CoV-2 replication kinetics and dissemination in the primary and secondary organs between mice with and without Down syndrome, suggesting that both groups have similar susceptibilities to SARS-CoV-2 infection. However, Down syndrome mice exhibited more severe disease as defined by clinical features including symptoms, weight loss, pulmonary function, and survival of mice. We found that increased disease severity in Down syndrome mice could not be attributed solely to increased infectivity or a more dramatic pro-inflammatory response to infection. Rather, results from RNA sequencing suggested that differences in the expression of genes from other physiological pathways, such as deficient oxidative phosphorylation, cardiopulmonary dysfunction, and deficient mucociliary clearance in the lungs may also contribute to heightened disease severity and mortality in Down syndrome mice following SARS-CoV-2 infection.

An ex vivo human precision-cut lung slice platform provides insight into SARS-CoV-2 pathogenesis and antiviral drug efficacy.

COVID-19 has claimed millions of lives since the emergence of SARS-CoV-2, and lung disease appears the primary cause of the death in COVID-19 patients. However, the underlying mechanisms of COVID-19 pathogenesis remain elusive, and there is no existing model where the human disease can be faithfully recapitulated and conditions for the infection process can be experimentally controlled. Herein we report the establishment of an ex vivo human precision-cut lung slice (hPCLS) platform for studying SARS-CoV-2 pathogenicity and innate immune responses, and for evaluating the efficacy of antiviral drugs against SARS-CoV-2. We show that while SARS-CoV-2 continued to replicate during the course of infection of hPCLS, infectious virus production peaked within 2 days, and rapidly declined thereafter. Although most proinflammatory cytokines examined were induced by SARS-CoV-2 infection, the degree of induction and types of cytokines varied significantly among hPCLS from individual donors, reflecting the heterogeneity of human populations. In particular, two cytokines (IP-10 and IL-8) were highly and consistently induced, suggesting a role in the pathogenesis of COVID-19. Histopathological examination revealed focal cytopathic effects late in the infection. Transcriptomic and proteomic analyses identified molecular signatures and cellular pathways that are largely consistent with the progression of COVID-19 in patients. Furthermore, we show that homoharringtonine, a natural plant alkaloid derived from Cephalotoxus fortunei , not only inhibited virus replication but also production of pro-inflammatory cytokines, and ameliorated the histopathological changes of the lungs caused by SARS-CoV-2 infection, demonstrating the usefulness of the hPCLS platform for evaluating antiviral drugs. SIGNIFICANCE: Here we established an ex vivo human precision-cut lung slice platform for assessing SARS-CoV-2 infection, viral replication kinetics, innate immune response, disease progression, and antiviral drugs. Using this platform, we identified early induction of specific cytokines, especially IP-10 and IL-8, as potential predictors for severe COVID-19, and uncovered a hitherto unrecognized phenomenon that while infectious virus disappears at late times of infection, viral RNA persists and lung histopathology commences. This finding may have important clinical implications for both acute and post-acute sequelae of COVID-19. This platform recapitulates some of the characteristics of lung disease observed in severe COVID-19 patients and is therefore a useful platform for understanding mechanisms of SARS-CoV-2 pathogenesis and for evaluating the efficacy of antiviral drugs.

Ocular Surface Disease in Glaucoma Patients.

PURPOSE: To review the most recent studies in the literature regarding the ocular surface in glaucoma patients and treatment options aimed to reduce ocular surface disease in this population. METHODS: We performed a literature search in the electronic databases of PubMed CENT RAL, Google Scholar, EMBASE the Register of Controlled Trials, and Ovid MEDLINE using the following terms: "ocular surface", "dry eye", "glaucoma", "selective laser trabeculoplasty", "glaucoma surgery", "preservatives", "preservative free", "ocular surface disease index", "tear break up time", "MMP-9" and "conjunctival hyperemia". RESULTS: Over the last several years, several studies have demonstrated the changes to the ocular surface in the setting of glaucoma, the best tests for markers of dry eye, and how management can be altered to help address ocular surface disease routinely or in preparation for glaucoma surgery. CONCLUSION: Ocular surface disease in the glaucoma patient population is widely recognized. It should be addressed to maximize patient compliance and quality of life.

Mitochondrial Triglyceride Dysregulation in Optic Nerves Following Indirect Traumatic Optic Neuropathy.

The purpose of this work is to identify mitochondrial optic nerve (ON) lipid alterations associated with sonication-induced traumatic optic neuropathy (TON). Briefly, a mouse model of indirect TON was generated using sound energy concentrated focally at the entrance of the optic canal using a laboratory sonifier (Branson Digital Sonifier 450, Danbury, CT, USA) with a microtip probe. We performed an analysis of a previously generated dataset from high-performance liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS). We analyzed lipids from isolated mitochondria from the ON at 1 day, 7 days, and 14 days post-sonication compared to non-sonicated controls. Lipid abundance alterations in post-sonicated ON mitochondria were evaluated with 1-way ANOVA (FDR-adjusted significant p-value < 0.01), debiased sparse partial correlation (DSPC) network modeling, and partial least squares-discriminant analysis (PLS-DA). We find temporal alterations in triglyceride metabolism are observed in ON mitochondria of mice following sonication-induced optic neuropathy with notable depletions of TG(18:1/18:2/18:2), TG(18:1/18:1/18:1), and TG(16:0/16:0/18:1). Depletion of mitochondrial triglycerides may mediate ON damage in indirect traumatic optic neuropathy through loss energy substrates for neuronal metabolism.

Potential of Application of Iron Chelating Agents in Ophthalmic Diseases.

The investigations discussed in this review indicate that iron may exacerbate different eye diseases. Therefore, it is plausible that reducing cellular or body iron stores could influence disease pathogenesis, so it is logical to consider the iron chelators' potential protective role in the various ophthalmic diseases in the form of topical eye drops or slow releasing injectable compounds as an adjuvant treatment.

Defective INPP5E distribution in NPHP1-related Senior-Loken syndrome.

BACKGROUND: Senior-Loken syndrome is a rare genetic disorder that presents with nephronophthisis and retinal degeneration, leading to end-stage renal disease and progressive blindness. The most frequent cause of juvenile nephronophthisis is a mutation in the nephronophthisis type 1 (NPHP1) gene. NPHP1 encodes the protein nephrocystin-1, which functions at the transition zone (TZ) of primary cilia. METHODS: We report a 9-year-old Senior-Loken syndrome boy with NPHP1 deletion, who presents with bilateral vision decrease and cystic renal disease. Renal function deteriorated to require bilateral nephrectomy and renal transplant. We performed immunohistochemistry, H&E staining, and electron microscopy on the renal sample to determine the subcellular distribution of ciliary proteins in the absence of NPHP1. RESULTS: Immunohistochemistry and electron microscopy of the resected kidney showed disorganized cystic structures with loss of cilia in renal tubules. Phosphoinositides have been recently recognized as critical components of the ciliary membrane and immunostaining of kidney sections for phosphoinositide 5-phosphatase, INPP5E, showed loss of staining compared to healthy control. Ophthalmic examination showed decreased electroretinogram consistent with early retinal degeneration. CONCLUSION: The decreased expression of INPP5E specifically in the primary cilium, coupled with disorganized cilia morphology, suggests a novel role of NPHP1 that it is involved in regulating ciliary phosphoinositide composition in the ciliary membrane of renal tubular cells.

Diarrhea as a Presenting Symptom of Coronavirus Disease 2019 in Children.

Gastroenteritis is common among children and is usually caused by bacterial, viral, or parasitic gastrointestinal infections. The occurrence of gastroenteritis as the only symptom of coronavirus disease 2019 (COVID-19) is an uncommon condition. We present a 16-month-old girl that has recently been admitted to our hospital with vomiting, diarrhea, and lethargy, who was ultimately diagnosed with COVID-19. This case shows that the clinical manifestations of COVID-19 can be misleading in children.

A Review on the Applications of Crowdsourcing in Human Pathology.

The advent of the digital pathology has introduced new avenues of diagnostic medicine. Among them, crowdsourcing has attracted researchers' attention in the recent years, allowing them to engage thousands of untrained individuals in research and diagnosis. While there exist several articles in this regard, prior works have not collectively documented them. We, therefore, aim to review the applications of crowdsourcing in human pathology in a semi-systematic manner. We first, introduce a novel method to do a systematic search of the literature. Utilizing this method, we, then, collect hundreds of articles and screen them against a predefined set of criteria. Furthermore, we crowdsource part of the screening process, to examine another potential application of crowdsourcing. Finally, we review the selected articles and characterize the prior uses of crowdsourcing in pathology.

Ocular Pathology of Oculocerebrorenal Syndrome of Lowe: Novel Mutations and Genotype-Phenotype Analysis.

Mutations in the OCRL1 gene result in the oculocerebrorenal syndrome of Lowe, with symptoms including congenital bilateral cataracts, glaucoma, renal failure, and neurological impairments. OCRL1 encodes an inositol polyphosphate 5-phosphatase which preferentially dephosphorylates phosphatidylinositide 4,5 bisphosphate (PI(4,5)P2). We have identified two novel mutations in two unrelated Lowe syndrome patients with congenital glaucoma. Novel deletion mutations are detected at c.739-742delAAAG in Lowe patient 1 and c.1595-1631del in Lowe patient 2. End stage glaucoma in patient 2 resulted in the enucleation of the eye, which on histology demonstrated corneal keloid, fibrous infiltration of the angle, ectropion uvea, retinal gliosis, and retinal ganglion cell loss. We measured OCRL protein levels in patient keratinocytes and found that Lowe 1 patient cells had significantly reduced OCRL protein as compared to the control keratinocytes. Genotype-phenotype correlation of OCRL1 mutations associated with congenital glaucoma revealed clustering of missense and deletion mutations in the 5-phosphatase domain and the RhoGAP-like domain. In conclusion, we report novel OCRL1 mutations in Lowe syndrome patients and the corresponding histopathologic analysis of one patient's ocular pathology.

In silico investigation of cornea deformation during irrigation/aspiration in phacoemulsification in cataract surgery.

To analyze the stress, strain and displacement of the human cornea under the action of negative intraocular pressure, which occurs during phacoemulsification in cataract surgery, a multidisciplinary approach including biomedical engineering, solid mechanics, numerical analysis, and fluid dynamics was used. Fluid-structure interaction method was implemented using 3-dimensional nonlinear finite element analysis of cornea tissue in conjunction with CFD analysis of anterior chamber fluid flow to study the deformation of the cornea under negative gage pressure during irrigation and aspiration (I/A). The computational model of the eye includes both cornea and sclera. To increase the accuracy of the computational model, both cornea hyperelasticity and thickness variation were included in the analysis. The simulation was performed for both coaxial and bimanual I/A systems with different flow rates. The cornea deformations for various flow rates were evaluated, and the possibility of an unstable anterior chamber was assessed. The results show that the critical pressure in the anterior chamber, which may lead to the surge condition due to buckling of the cornea, is sub-ambient (below zero gauge pressure). Anterior chamber instability occurs at higher volume flow rates for coaxial I/A system compared with that for bimanual system, but the deformation of the cornea is more intense for the bimanual system.

Relationship between saccadic eye movements and formation of the Krukenberg's spindle-a CFD study.

In this research, a series of numerical simulations for evaluating the effects of saccadic eye movement on the aqueous humour (AH) flow field and movement of pigment particles in the anterior chamber (AC) was performed. To predict the flow field of AH in the AC, the unsteady forms of continuity, momentum balance and conservation of energy equations were solved using the dynamic mesh technique for simulating the saccadic motions. Different orientations of the human eye including horizontal, vertical and angles of 10° and 20° were considered. The Lagrangian particle trajectory analysis approach was used to find the trajectories of pigment particles in the eye. Particular attention was given to the relation between the saccadic eye movement and potential formation of Krukenberg's spindle in the eye. The simulation results revealed that the natural convection flow was an effective mechanism for transferring pigment particles from the iris to near the cornea. In addition, the saccadic eye movement was the dominant mechanism for deposition of pigment particles on the cornea, which could lead to the formation of Krukenberg's spindle. The effect of amplitude of saccade motion angle in addition to the orientation of the eye on the formation of Krukenberg's spindle was investigated.

Physiology of aqueous humor dynamic in the anterior chamber due to rapid eye movement.

The nature of aqueous humor (AH) mixing in the anterior chamber (AC) of the human eye due to rapid eye movement (REM) has not been fully understood and has been somewhat a controversial issue. This study uses a computational modeling approach to shed light on this issue. For this purpose a numerical method was developed and used to solve the mathematical equations governing the flow and mixing of aqueous humor motion in the eye subjected to such movements. Based on the experimental measurements available in the literature for the average and maximum amplitudes of the eye movements, a harmonic model for the REM was developed. The corresponding instantaneous and time-averaged velocity fields were evaluated. The simulation results showed that, contrary to earlier reports, the REM led to complex flow structures and a 3-D mixing of AH in the anterior chamber. In addition, the mixing velocity increased in direct proportion to the REM amplitudes. Thus, the AC flow generated by REM could carry nutrients to the posterior surface of the cornea during the sleep. Furthermore, the shear stress acting on the corneal endothelial cells due to REM was computed and compared with that of buoyancy driven flow in the AC due to temperature gradient. It was found that the shear stress generated by REM is much higher than that introduced by the natural convection. A video file for providing a better understanding of the AH mixing process in the AC was also prepared. This video is available on the web.

High glucose and diabetes modulate cellular proteasome function: Implications in the pathogenesis of diabetes complications.

The precise link between hyperglycemia and its deleterious effects on retinal and kidney microvasculature, and more specifically loss of retinal perivascular supporting cells including smooth muscle cell/pericytes (SMC/PC), in diabetes are not completely understood. We hypothesized that differential cellular proteasome activity contributes to sensitivity of PC to high glucose-mediated oxidative stress and vascular rarefaction. Here we show that retinal endothelial cells (EC) have significantly higher proteasome peptidase activity compared to PC. High glucose treatment (HGT) increased the level of total ubiquitin-conjugated proteins in cultured retinal PC and EC, but not photoreceptor cells. In addition, in vitro proteasome activity assays showed significant impairment of proteasome chymotrypsin-like peptidase activity in PC, but not EC. The PA28-α/-ß and PA28-ß/-γ protein levels were also higher in the retina and kidney glomeruli of diabetic mice, respectively. Our results demonstrate, for the first time, that high glucose has direct biological effects on cellular proteasome function, and this modulation might be protective against cellular stress or damage induced by high glucose.

Saccade movements effect on the intravitreal drug delivery in vitreous substitutes: a numerical study.

In this study, the distributions of intravitreal injected drugs in post-vitrectomy human eyes, which are subjected to periodic saccade movements, are investigated. The computational model for the vitreous cavity of human eye is a sphere with one side truncated by the eye lens. A dynamic mesh technique was used to model the eye motion and the unsteady 3-D forms of continuity; Navier-Stokes and concentration transport of drug equations were solved numerically. The numerical model was validated earlier for the vitreous liquid flow field. The predicted drug concentration for idealized geometry was compared with the available analytic solution and excellent agreement was observed. The validated computer model was then used to simulate a real vitreous cavity filled with Balanced Salt Solution or aqueous humor as a vitreous substitute in order to obtain distribution of drugs in the post-vitrectomy eyes or liquefied vitreous. Additionally, effects of locations of drug injection, drug diffusion coefficients and saccade amplitude on the drug distribution and its uniformity were investigated. Although the earlier findings in the literature reported a day or a week as a needed time for drug uniform distribution in the vitreous substitutes, the present work depicts that saccade movements augment the transport of the drug in a way that the uniformity of the drug distribution can be achieved in a matter of minutes. Furthermore, in a vitreous cavity subjected to the saccade movements, the diffusion coefficient of drugs does not significantly affect their distribution after a few minutes. Even the injection location does not matter as uniform distribution is achieved after some time.

Optic nerve disease and axon pathophysiology.

Optic neuropathy is the most common cause of irreversible blindness worldwide. Although the most common optic neuropathy is glaucoma, there are also many other optic neuropathies, for example, those associated with multiple sclerosis, giant cell arteritis, ischemia, and many other diseases. In almost all cases, the pathogenesis involves injury to the retinal ganglion cell axon, with consequent somal and axonal degeneration. This chapter reviews the clinical and pathophysiological properties associated with three of the most common optic neuropathies, as well as recent findings in understanding axonal degeneration. It concludes with a status report on therapies for optic nerve disease, including axoprotection, an approach being studied that has the goal of maintaining axonal integrity and function after injury.

Investigation of saccadic eye movement effects on the fluid dynamic in the anterior chamber.

The aqueous humor (AH) flow in the anterior chamber (AC) due to saccadic movements is investigated in this research. The continuity, Navier-Stokes and energy equations in 3D and unsteady forms are solved numerically and the saccadic motion was modeled by the dynamic mesh technique. Firstly, the numerical model was validated for the saccadic movement of a spherical cavity with analytic solutions and experimental data where excellent agreement was observed. Then, two types of periodic and realistic saccadic motions of the AC are simulated, whereby the flow field is computed for various saccade amplitudes and the results are reported for different times. The results show that the acting shear stress on the corneal endothelial cells from AH due to saccadic movements is much higher than that due to normal AH flow by buoyancy induced due to temperature gradient. This shear stress is higher on the central region of the cornea. The results also depict that eye saccade imposes a 3D complicated flow field in the AC consist of various vortex structures. Finally, the enchantment of heat transfer in the AC by AH mixing as a result of saccadic motion is investigated.

Effect of transcutaneous electrical stimulation on rabbit corneal epithelial cell migration.

PURPOSE: To evaluate the effect of transcutaneous application of electrical stimulation on the rate of corneal epithelial healing in corneal abrasion using an in vivo model of corneal wound healing in the rabbit. METHODS: This was an experimental study including 16 adult Dutch rabbits that were randomly allocated to 2 study groups (8 in each group) to receive transcutaneous electrostimulation or no treatment. The corneal epithelium was lifted from the round limbal border. The rabbits in the study group received transcutaneous electrostimulation for 30 minutes by placing the active electrode (-) on the upper right lid and the passive electrode (+) on the right foot. Photographs of corneal epithelial defects were taken each day until the sixth day by digital photographs and the images were analyzed using software. RESULTS: The healing percentage was significantly higher in those who received transcutaneous electrostimulation at days 2 (P < 0.001), 3 (P < 0.001), 4 (P = 0.001), and 6 (P = 0.014) after the procedure. The healing rate was also significantly higher in the transcutaneous electrostimulation group at days 2 (P < 0.001), 5 (P = 0.022), and 6 (P = 0.044) after the procedure. The healing rate did not differ significantly between the groups at days 3 (P = 0.169) and 4 (P = 0.426). The maximum healing rate was observed in the first 24 hours, and the minimum healing rate was observed during day 3 in the electrical stimulation group. CONCLUSIONS: The transcutaneous application of electrical stimulation can considerably increase the rate of corneal healing, especially in the first 24 hours of healing full surface corneal abrasion.