Increased Glaucoma Case-finding Through Routine Optical Coherence Tomography in Optometry Practice.

OBJECTIVE: Timely detection of glaucoma is key to preventing or delaying vision loss. This study aimed to assess whether the routine use of optical coherence tomography (OCT) by optometrists for detection of glaucomatous changes in the optic nerve and retina increased glaucoma referrals to ophthalmologists. DESIGN: This study was a retrospective review of routinely-collected electronic medical records of patients from a chain of 331 optometry practices in Australia. PARTICIPANTS: Electronic medical records were reviewed for every patient aged 18-99 years who attended an included practice between January 1 and July 31, 2019. METHODS: Odds of referral for glaucoma assessment were compared between practices performing OCT routinely on all patients (OCT practices, n=175) and without OCT (non-OCT practices, n=20). A subset of referrals were assessed by ophthalmologists to determine the false positive referral rate. MAIN OUTCOME MEASURES: The primary outcome measure of this study was referral to an ophthalmologist for glaucoma assessment. A secondary outcome was the rate of false positive referrals, analysed in a subset of patients referred for glaucoma assessment. RESULTS: Records from 994,461 patients (59% female) were included and 10,475 (1.1%) were referred for glaucoma assessment. Most referrals were associated with normal intraocular pressure (non-OCT practices: n=496, 66%; OCT practices: n=6,603, 68%). Referral for glaucoma was higher in OCT practices (n=9,719, 1.1%) compared to non-OCT practices (n=756, 0.8%, age-, gender- and location-adjusted odds ratio 1.39, 95% confidence interval 1.10-1.76). Of 318 referred patients (3%, all from OCT practices) for whom ophthalmologist feedback was available, 68 (21%) were considered not to have glaucoma. CONCLUSIONS: The routine use of OCT in optometric practice may lead to more timely glaucoma detection and prevention of avoidable vision loss.

A biocompatible reverse thermoresponsive polymer for ocular drug delivery.

Age-related macular degeneration (AMD) is a leading cause of vision loss, the treatment of which may require monthly intravitreal injections. This is a burden on patients and health services, and new delivery modalities that reduce injection frequency are required. To that end, we investigated the suitability of a novel reverse thermoresponsive polymer (RTP) as an ocular drug-delivery vehicle. In this work, we detail the structure and synthesis of a novel RTP, and determine drug release curves for two drugs commonly used in the treatment of AMD, bevacizumab and aflibercept. Biocompatibility of the RTP was assessed in vitro in human and rat cell lines and in vivo following intravitreal injection in rats. Bevacizumab demonstrated a more appropriate release profile than aflibercept, with 67% released within 14 days and 78% released in total over a 183-day period. No toxic effects of RTP were seen in human or rat cells in up to 14 days of co-culture with RTP. Following intravitreal injection, intraocular pressure was unaffected by the presence of RTP and no changes in retinal function or structure were observed at 1 week or 1 month post-injection. RTP injection did not cause inflammation, gliosis or apoptosis in the retina. This work demonstrates the potential suitability of the novel RTP as a sustained-release vehicle for ocular drug delivery for anti-neovascular therapies. Optimization of polymer chemistry for optimal drug loading and release is needed.

Metformin induces distinct bioenergetic and metabolic profiles in sensitive versus resistant high grade serous ovarian cancer and normal fallopian tube secretory epithelial cells.

Metformin is a widely used agent for the treatment of diabetes and infertility, however, it has been found to have anti-cancer effects in a variety of malignancies including high grade serous ovarian cancer (HGSC). Studies describing the mechanisms by which metformin affects HGSC are ongoing, but detailed analysis of its effect on the cellular metabolism of both HGSC cells and their precursor, normal fallopian tube secretory epithelial cells (FTSECs), is lacking. We addressed the effects of metformin and the more potent biguanide, phenformin, on HGSC cell lines and normal immortalized FTSECs. Cell proliferation assays identified that FTSECs and a subset of HGSC cell lines are relatively resistant to the anti-proliferative effects of metformin. Bioenergetic and metabolomic analyses were used to metabolically differentiate the metformin-sensitive and metformin-resistant cell lines. Bioenergetically, biguanides elicited a significant decrease in mitochondrial respiration in all HGSC cells and FTSECs. However, biguanides had a greater effect on mitochondrial respiration in metformin sensitive cells. Metabolomic analysis revealed that metformin and phenformin generally induce similar changes in metabolic profiles. Biguanide treatment led to a significant increase in NADH in FTSECs and HGSC cells. Interestingly, biguanide treatment induced changes in the levels of mitochondrial shuttle metabolites, glycerol-3-phopshate (G3P) and aspartate, specifically in HGSC cell lines and not in FTSECs. Greater alterations in G3P or aspartate levels were also found in metformin sensitive cells relative to metformin resistant cells. These data identify bioenergetic and HGSC-specific metabolic effects that correlate with metformin sensitivity and novel metabolic avenues for possible therapeutic intervention.

Glucose deprivation elicits phenotypic plasticity via ZEB1-mediated expression of NNMT.

Glucose is considered the primary energy source for all cells, and some cancers are addicted to glucose. Here, we investigated the functional consequences of chronic glucose deprivation in serous ovarian cancer cells. We found that cells resistant to glucose starvation (glucose-restricted cells) demonstrated increased metabolic plasticity that was dependent on NNMT (Nicotinamide N-methyltransferase) expression. We further show that ZEB1 induced NNMT, rendered cells resistant to glucose deprivation and recapitulated metabolic adaptations and mesenchymal gene expression observed in glucose-restricted cells. NNMT depletion reversed metabolic plasticity in glucose-restricted cells and prevented de novo formation of glucose-restricted colonies. In addition to its role in glucose independence, we found that NNMT was required for other ZEB1-induced phenotypes, such as increased migration. NNMT protein levels were also elevated in metastatic and recurrent tumors compared to matched primary carcinomas, while normal ovary and fallopian tube tissue had no detectable NNMT expression. Our studies define a novel ZEB1/NNMT signaling axis, which elicits mesenchymal gene expression, as well as phenotypic and metabolic plasticity in ovarian cancer cells upon chronic glucose starvation. Understanding the causes of cancer cell plasticity is crucial for the development of therapeutic strategies to counter intratumoral heterogeneity, acquired drug resistance and recurrence in high-grade serous ovarian cancer (HGSC).

Sphingosine kinase 1 is required for TGF-ß mediated fibroblastto- myofibroblast differentiation in ovarian cancer.

Sphingosine kinase 1 (SPHK1), the enzyme that produces sphingosine 1 phosphate (S1P), is known to be highly expressed in many cancers. However, the role of SPHK1 in cells of the tumor stroma remains unclear. Here, we show that SPHK1 is highly expressed in the tumor stroma of high-grade serous ovarian cancer (HGSC), and is required for the differentiation and tumor promoting function of cancer-associated fibroblasts (CAFs). Knockout or pharmacological inhibition of SPHK1 in ovarian fibroblasts attenuated TGF-ß-induced expression of CAF markers, and reduced their ability to promote ovarian cancer cell migration and invasion in a coculture system. Mechanistically, we determined that SPHK1 mediates TGF-ß signaling via the transactivation of S1P receptors (S1PR2 and S1PR3), leading to p38 MAPK phosphorylation. The importance of stromal SPHK1 in tumorigenesis was confirmed in vivo, by demonstrating a significant reduction of tumor growth and metastasis in SPHK1 knockout mice. Collectively, these findings demonstrate the potential of SPHK1 inhibition as a novel stroma-targeted therapy in HGSC.

Succinate dehydrogenase inhibition leads to epithelial-mesenchymal transition and reprogrammed carbon metabolism.

BACKGROUND: Succinate dehydrogenase (SDH) is a mitochondrial metabolic enzyme complex involved in both the electron transport chain and the citric acid cycle. SDH mutations resulting in enzymatic dysfunction have been found to be a predisposing factor in various hereditary cancers. Therefore, SDH has been implicated as a tumor suppressor. RESULTS: We identified that dysregulation of SDH components also occurs in serous ovarian cancer, particularly the SDH subunit SDHB. Targeted knockdown of Sdhb in mouse ovarian cancer cells resulted in enhanced proliferation and an epithelial-to-mesenchymal transition (EMT). Bioinformatics analysis revealed that decreased SDHB expression leads to a transcriptional upregulation of genes involved in metabolic networks affecting histone methylation. We confirmed that Sdhb knockdown leads to a hypermethylated epigenome that is sufficient to promote EMT. Metabolically, the loss of Sdhb resulted in reprogrammed carbon source utilization and mitochondrial dysfunction. This altered metabolic state of Sdhb knockdown cells rendered them hypersensitive to energy stress. CONCLUSIONS: These data illustrate how SDH dysfunction alters the epigenetic and metabolic landscape in ovarian cancer. By analyzing the involvement of this enzyme in transcriptional and metabolic networks, we find a metabolic Achilles' heel that can be exploited therapeutically. Analyses of this type provide an understanding how specific perturbations in cancer metabolism may lead to novel anticancer strategies.

Retinal oxygen saturation: novel analysis method for the oxymap.

PURPOSE: To use a novel image analysis approach to consider how oxygen saturation changes as a function of vessel width and distance from the nerve and between superior and inferior retinal hemifields. METHODS: Ten images were acquired from one eye of 17 participants (mean [standard deviation] age, 28 [4] years; range, 22-38 years) using the Oxymap T1 retinal oximeter. Every pixel identified by the detection algorithm was extracted, and frequency histograms of retinal vessel oxygen saturation were plotted for each vessel diameter (70-170 µm). Histograms were fitted with two Gaussian models to identify peak arteriole and venule oxygen saturation. Mean (±standard error of the mean) arteriole and venule oxygen saturation at each vessel width were calculated. Data were also analyzed in (1) annuli of 100 µm centered on the optic nerve or (2) upper and lower hemifields demarcated by the center of the optic nerve. RESULTS: Venous oxygen saturation was higher in smaller vessels than in larger vessels. Arterial oxygen saturation remained relatively constant with vessel width. Oxygen saturation was lower in veins nearer the optic nerve. The upper retinal hemisphere showed higher venous oxygen saturation compared with the lower hemifield. CONCLUSIONS: The current objective analysis approach provides a more complete picture of retinal oxygen saturation at the posterior pole as a function of vessel width and retinal location.