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Gary W Jerkins,1 Guruprasad R Pattar,2 Shane R Kannarr3 1Advancing Vision Research, Nashville, TN, USA; 2The Eye Care Institute, Louisville, KY, USA; 3Kannarr Eye Care, Pittsburg, KS, USACorrespondence: Gary W JerkinsAdvancing Vision Associates, 4306 Harding Pike, Nashville, TN 37205, USATel +1 615 502-2871Email drjeyeguy@garyjerkins.comAbstract: Keratoconjunctivitis sicca (KCS) is a multifactorial disease characterized by tear hyperosmolarity, inflammation, and ocular surface damage. Cyclosporine A (CsA) is used as an effective disease-modifying agent to improve the signs and symptoms of KCS by reducing inflammation, which interferes with tear production. This review provides an overview of efficacy, safety, and limitations of currently marketed topical CsA formulations—including CsA ophthalmic emulsion, cationic nanoemulsion, and aqueous nanomicelles—and highlights newer technologies for controlled ocular delivery of CsA and their clinical implications. Long available emulsion formulations of CsA are oil-based and have several limitations, including slow onset of efficacy and low intraocular penetration and bioavailability. Aqueous CsA nanomicelle carriers produce rapid improvement in objective signs of KCS such as corneal and conjunctival staining as early as 4 weeks and have acceptable safety profiles. CsA formulations using semifluorinated alkanes or polyaphrons are currently in clinical development, having recently completed Phase 2 studies. Other carriers for CsA currently in the preclinical phase include microemulsions, polymeric aqueous and lyophilized micelles, and hydrogels; these novel formulations have yet to undergo clinical trials. Formulations that improve tissue availability of CsA may be beneficial in clinical practice by providing faster onset of relief and improving patient adherence.Keywords: cyclosporine A, keratoconjunctivitis sicca, emulsion, nanomicelles, OTX-101

Purpose: Dry eye disease is a multifactorial disorder that affects the ocular surface, with symptoms including ocular irritation, impaired vision, and pain. Nicotinic acetylcholine receptor (nAChR) agonists are novel treatments for dry eye disease; this study investigates the nAChR agonist OC-02 (simpinicline solution) as an aqueous nasal spray., Methods: PEARL (Clinical Trial to Evaluate the Efficacy of OC-02 Nasal Spray on Signs and Symptoms of Dry Eye Disease) was a Phase II study that evaluated the efficacy and safety of OC-02 (simpinicline solution) nasal spray (OC-02 SNS) in adult patients with dry eye disease. Patients ≥22 years of age were eligible if they had an Ocular Surface Disease Index score ≥23, corneal fluorescein staining score ≥2 in >1 region or ≥4 for all regions, or Schirmer test score (STS) ≤10 mm; there were no restrictions on eye dryness score (EDS). Patients (N = 165) were randomly assigned 1:1:1:1 to vehicle (control; n = 42) or OC-02 SNS (0.11 mg, 0.55 mg, or 1.1 mg; n = 41 per group) and received a single dose of study drug (100 µL using a nasal spray atomizer) at visit 1 and visit 2 (15-19 days after visit 1). Primary efficacy outcomes were change in the STS from baseline to immediately after treatment administration (visit 1) and change in the EDS from before to 5 minutes after treatment during controlled adverse environment exposure (visit 2)., Findings: Baseline demographic and ocular clinical characteristics were similar across all groups. Single-dose OC-02 SNS improved the signs and symptoms of dry eye disease. For the STS, statistically significant and dose-dependent improvements were found from before to after treatment with OC-02 SNS versus vehicle (least-squares mean change from baseline: vehicle, 3.0 mm; 0.11 mg OC-02 SNS, 9.0 mm; 0.55 mg, 17.5 mm; and 1.1 mg, 19.6 mm). For EDS, statistically significant and dose-dependent improvements were found from before to 5 minutes after treatment with higher doses of OC-02 SNS versus vehicle (least-squares mean change from baseline: vehicle, -6.5; 0.11 mg OC-02 SNS, -9.4; 0.55 mg, -17.4; and 1.1 mg, -20.7). OC-02 SNS was well tolerated: only 2 ocular adverse events were reported (eye pruritis and keratitis), and the most common nonocular events were cough and throat irritation., Implications: Single-dose OC-02 SNS over a range of doses immediately and significantly increased tear production and improved eye dryness. Together with previous studies of OC-01 (varenicline solution) nasal spray, our findings suggest that agonist stimulation of nAChRs in the nasal cavity is a valid and effective mechanism to elicit natural tear production in patients with dry eye disease., Clinicaltrials: gov identifier: NCT03452397., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the safety and effectiveness of the intranasal tear neurostimulator (ITN) in improving dry eye symptoms assessed in a controlled adverse environment (CAE®)., Methods: Study 1: Multicenter, subject-masked, randomized-sequence, crossover design. Single intranasal (active) and extranasal (control) ITN administration during CAE exposure. Study 2: Single-arm, open-label design. Intranasal ITN administration ≥2 times/day for 45 days, CAE assessment at days 0 and 45. In both studies, upon CAE entry, and every 5 min thereafter, subjects assessed eye dryness score (visual analog scale, 0-100 mm; EDS-VAS), and ocular discomfort score (ODS; Ora Calibra™, 0-4), for ≈2 h. Study 1: when ODS was ≥3 at 2 consecutive timepoints, subjects applied ITN intranasally or extranasally for ≈3 min, and again when achieving the same ODS criteria in randomized sequence. Study 2: days 0 and 45, ITN was applied for ≈3 min employing the same ODS criteria as Study 1., Results: Study 1: Significantly greater pre- to post-application reductions in mean [SEM] EDS (-16.5 [1.7] vs -3.1 [1.7], P < 0.0001) and ODS (-0.93 [0.08] vs -0.34 [0.08], P < 0.0001; n = 143) with intranasal vs extranasal stimulation. Study 2: On day 0 (n = 52) and day 45 (n = 48), significant pre- to post-application reductions in mean [SEM] EDS (-15.9 [2.7] and -15.2 [2.4]; P < 0.0001), and ODS (-1.3 [0.2] and -1.3 [0.1]; P < 0.0001). Few device-related adverse events were reported, none serious., Conclusions: Acute symptom relief is significant with the ITN and remains undiminished after daily use., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate efficacy and survival rates of intraocular pressure (IOP)-lowering effect obtained with phacoemulsification (phaco) alone or in combination with canaloplasty (PCP) in patients with open-angle glaucoma (OAG)., Methods: Retrospective chart review of consecutive cases at the Department of Ophthalmology, Indiana University. Visual acuity (VA), IOP, number of medications (Meds), failures, and survival rates of IOP-lowering effect were analyzed. Inclusion criteria were: patients older than 18 years with OAG and cataract. Exclusion criteria were: no light perception vision, prior glaucoma surgery, chronic uveitis, angle-closure glaucoma, and advanced-stage or end-stage OAG. Failure criteria were: IOP>21 mm Hg or <20% reduction, IOP<6 mm Hg, further glaucoma surgeries, and loss of light perception vision., Results: Thirty-seven patients underwent phaco and 32 patients had PCP. Follow-up was 21.8±10.1 versus 18.8±9.6 months for phaco and PCP, respectively (P=0.21). Age (y) (74.7±9.8 vs. 76.1±8.3, P=0.54), sex (P=81), and laser status (P=0.75) were similar between the groups. Preoperatively, mean±SD logMAR VA (0.5±0.7 vs. 0.5±0.5, P=0.77), IOP (16.2±4.6 vs. 18.2±5.1, P=0.13), and Meds (1.4±1.1 vs. 1.3±0.7, P=0.75) were similar for phaco and PCP, respectively. At 24-month phaco (n=17) and PCP (n=11), respectively, mean±SD were: logMAR VA 0.2±0.2 versus 0.4±0.7, P=0.29; IOP 14.1±4.0 versus 12.9±3.8, P=0.43; and Meds 1.5±1.2 versus 0.3±0.5, P=0.005. Rates of successful IOP lowering without medications for phaco versus PCP at 12 months were 34% versus 75%, respectively (P=0.003)., Conclusions: A combination of canaloplasty with phaco results in a decreased number of glaucoma medications and increased survival rate of IOP-lowering effect compared with phaco alone.

Hyperinsulinemia is known to promote the progression/worsening of insulin resistance. Evidence reveals a hidden cost of hyperinsulinemia on plasma membrane (PM) phosphatidylinositol 4,5-bisphosphate (PIP(2))-regulated filamentous actin (F-actin) structure, components critical to the normal operation of the insulin-regulated glucose transport system. Here we delineated whether increased glucose flux through the hexosamine biosynthesis pathway (HBP) causes PIP(2)/F-actin dysregulation and subsequent insulin resistance. Increased glycosylation events were detected in 3T3-L1 adipocytes cultured under conditions closely resembling physiological hyperinsulinemia (5 nm insulin; 12 h) and in cells in which HBP activity was amplified by 2 mm glucosamine (GlcN). Both the physiological hyperinsulinemia and experimental GlcN challenge induced comparable losses of PIP(2) and F-actin. In addition to protecting against the insulin-induced membrane/cytoskeletal abnormality and insulin-resistant state, exogenous PIP(2) corrected the GlcN-induced insult on these parameters. Moreover, in accordance with HBP flux directly weakening PIP(2)/F-actin structure, pharmacological inhibition of the rate-limiting HBP enzyme [glutamine-fructose-6-phosphate amidotransferase (GFAT)] restored PIP(2)-regulated F-actin structure and insulin responsiveness. Conversely, overexpression of GFAT was associated with a loss of detectable PM PIP(2) and insulin sensitivity. Even less invasive challenges with glucose, in the absence of insulin, also led to PIP(2)/F-actin dysregulation. Mechanistically we found that increased HBP activity increased PM cholesterol, the removal of which normalized PIP(2)/F-actin levels. Accordingly, these data suggest that glucose transporter-4 functionality, dependent on PIP(2) and/or F-actin status, can be critically compromised by inappropriate HBP activity. Furthermore, these data are consistent with the PM cholesterol accrual/toxicity as a mechanistic basis of the HBP-induced defects in PIP(2)/F-actin structure and impaired glucose transporter-4 regulation.

We recently found that plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP(2))-regulated filamentous actin (F-actin) polymerization was diminished in hyperinsulinemic cell culture models of insulin resistance. Here we delineated whether increased glucose flux through the hexosamine biosynthesis pathway (HBP) causes the PIP(2)/F-actin dysregulation and insulin resistance induced by hyperinsulinemia. Increased HBP activity was detected in 3T3-L1 adipocytes cultured under conditions closely resembling physiological hyperinsulinemia (5 nm insulin for 12 h) and in cells where HBP activity was amplified by 2 mm glucosamine (GlcN). Both the physiological hyperinsulinemia and experimental GlcN challenge induced comparable losses of PIP(2) and F-actin. In addition to protecting against the insulin-induced membrane/cytoskeletal abnormality and insulin-resistant state, exogenous PIP(2) corrected the GlcN-induced insult on these parameters. Moreover, in accordance with HBP flux directly weakening PIP(2)/F-actin structure, inhibition of the rate-limiting HBP enzyme (glutamine:fructose-6-phosphate amidotransferase) restored PIP(2)-regulated F-actin structure and insulin responsiveness. Conversely, overexpression of glutamine:fructose-6-phosphate amidotransferase was associated with a loss of detectable plasma membrane PIP(2) and insulin sensitivity. A slight decrease in intracellular ATP resulted from amplifying HBP by hyperinsulinemia and GlcN. However, experimental maintenance of the intracellular ATP pool under both conditions with inosine did not reverse the PIP(2)/F-actin-based insulin-resistant state. Furthermore, less invasive challenges with glucose, in the absence of insulin, also led to PIP(2)/F-actin dysregulation. Accordingly, we suggest that the functionality of cell systems dependent on PIP(2) and/or F-actin status, such as the glucose transport system, can be critically compromised by inappropriate HBP activity.

Since trivalent chromium (Cr(3+)) enhances glucose metabolism, interest in the use of Cr(3+)as a therapy for type 2 diabetes has grown in the mainstream medical community. Moreover, accumulating evidence suggests that Cr(3+) may also benefit cardiovascular disease (CVD) and atypical depression. We have found that cholesterol, a lipid implicated in both CVD and neurodegenerative disorders, also influences cellular glucose uptake. A recent study in our laboratory shows that exposure of 3T3-L1 adipocytes to chromium picolinate (CrPic, 10 nM) induces a loss of plasma membrane cholesterol. Concomitantly, accumulation of intracellularly sequestered glucose transporter GLUT4 at the plasma membrane was dependent on the CrPic-induced cholesterol loss. Since CrPic supplementation has the greatest benefit on glucose metabolism in hyperglycemic insulin-resistant individuals, we asked here if the CrPic effect on cells was glucose-dependent. We found that GLUT4 redistribution in cells treated with CrPic occurs only in cells cultured under high glucose (25 mM) conditions that resemble the diabetic-state, and not in cells cultured under non-diabetic (5.5 mM glucose) conditions. Examination of the effect of CrPic on proteins involved in cholesterol homeostasis revealed that the activity of sterol regulatory element-binding protein (SREBP), a membrane-bound transcription factor ultimately responsible for controlling cellular cholesterol balance, was upregulated by CrPic. In addition, ABCA1, a major player in mediating cholesterol efflux was decreased, consistent with SREBP transcriptional repression of the ABCA1 gene. Although the exact mechanism of Cr(3+)-induced cholesterol loss remains to be determined, these cellular responses highlight a novel and significant effect of chromium on cholesterol homeostasis. Furthermore, these findings provide an important clue to our understanding of how chromium supplementation might benefit hypercholesterolemia-associated disorders.

Evidence suggests that chromium supplementation may alleviate symptoms associated with diabetes, such as high blood glucose and lipid abnormalities, yet a molecular mechanism remains unclear. Here, we report that trivalent chromium in the chloride (CrCl3) or picolinate (CrPic) salt forms mobilize the glucose transporter, GLUT4, to the plasma membrane in 3T3-L1 adipocytes. Concomitant with an increase in GLUT4 at the plasma membrane, insulin-stimulated glucose transport was enhanced by chromium treatment. In contrast, the chromium-mobilized pool of transporters was not active in the absence of insulin. Microscopic analysis of an exofacially Myc-tagged enhanced green fluorescent protein-GLUT4 construct revealed that the chromium-induced accumulation of GLUT4-containing vesicles occurred adjacent to the inner cell surface membrane. With insulin these transporters physically incorporated into the plasma membrane. Regulation of GLUT4 translocation by chromium did not involve known insulin signaling proteins such as the insulin receptor, insulin receptor substrate-1, phosphatidylinositol 3-kinase, and Akt. Consistent with a reported effect of chromium on increasing membrane fluidity, we found that chromium treatment decreased plasma membrane cholesterol. Interestingly, cholesterol add-back to the plasma membrane prevented the beneficial effect of chromium on both GLUT4 mobilization and insulin-stimulated glucose transport. Furthermore, chromium action was absent in methyl-beta-cyclodextrin-pretreated cells already displaying reduced plasma membrane cholesterol and increased GLUT4 translocation. Together, these data reveal a novel mechanism by which chromium may enhance GLUT4 trafficking and insulin-stimulated glucose transport. Moreover, these findings at the level of the cell are consistent with in vivo observations of improved glucose tolerance and decreased circulating cholesterol levels after chromium supplementation.

Muscle and fat cells develop insulin resistance when cultured under hyperinsulinemic conditions for sustained periods. Recent data indicate that early insulin signaling defects do not fully account for the loss of insulin action. Given that cortical filamentous actin (F-actin) represents an essential aspect of insulin regulated glucose transport, we tested to see whether cortical F-actin structure was compromised during chronic insulin treatment. The acute effect of insulin on GLUT4 translocation and glucose uptake was diminished in 3T3-L1 adipocytes exposed to a physiological level of insulin (5 nm) for 12 h. This insulin-induced loss of insulin responsiveness was apparent under both low (5.5 mm) and high (25 mm) glucose concentrations. Microscopic and biochemical analyses revealed that the hyperinsulinemic state caused a marked loss of cortical F-actin. Since recent data link phosphatidylinositol 4,5-bisphosphate (PIP(2)) to actin cytoskeletal mechanics, we tested to see whether the insulin-resistant condition affected PIP(2) and found a noticeable loss of this lipid from the plasma membrane. Using a PIP(2) delivery system, we replenished plasma membrane PIP(2) in cells following the sustained insulin treatment and observed a restoration in cortical F-actin and insulin responsiveness. These data reveal a novel molecular aspect of insulin-induced insulin resistance involving defects in PIP(2)/actin regulation.