A novel platelet activating factor receptor antagonist reduces cell infiltration and expression of inflammatory mediators in mice exposed to desiccating conditions after PRK

Combined Therapy With Avastin, a PAF Receptor Antagonist and a Lipid Mediator Inhibited Glioblastoma Tumor Growth

Glioblastoma multiforme (GBM) is an aggressive, highly proliferative, invasive brain tumor with a poor prognosis and low survival rate. The current standard of care for GBM is chemotherapy combined with radiation following surgical intervention, altogether with limited efficacy, since survival averages 18 months. Improvement in treatment outcomes for patients with GBM requires a multifaceted approach due to the dysregulation of numerous signaling pathways. Recently emerging therapies to precisely modulate tumor angiogenesis, inflammation, and oxidative stress are gaining attention as potential options to combat GBM. Using a mouse model of GBM, this study aims to investigate Avastin (suppressor of vascular endothelial growth factor and anti-angiogenetic treatment), LAU-0901 (a platelet-activating factor receptor antagonist that blocks pro-inflammatory signaling), Elovanoid; ELV, a novel pro-homeostatic lipid mediator that protects neural cell integrity and their combination as an alternative treatment for GBM. Female athymic nude mice were anesthetized with ketamine/xylazine, and luciferase-modified U87MG tumor cells were stereotactically injected into the right striatum. On post-implantation day 13, mice received one of the following: LAU-0901, ELV, Avastin, and all three compounds in combination. Bioluminescent imaging (BLI) was performed on days 13, 20, and 30 post-implantation. Mice were perfused for ex vivo MRI on day 30. Bioluminescent intracranial tumor growth percentage was reduced by treatments with LAU-0901 (43%), Avastin (77%), or ELV (86%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 72, 92, and 96%, respectively. Additionally, tumor reduction was confirmed by MRI on day 30, which shows a decrease in tumor volume by treatments with LAU-0901 (37%), Avastin (67%), or ELV (81.5%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 69, 78.7, and 88.6%, respectively. We concluded that LAU-0901 and ELV combined with Avastin exert a better inhibitive effect in GBM progression than monotherapy. To our knowledge, this is the first study that demonstrates the efficacy of these novel therapeutic regimens in a model of GBM and may provide the basis for future therapeutics in GBM patients.

Platelet activating factor in the eye: Physiological roles, diseases and future perspectives

Platelet Activating Factor (PAF) is a known phospholipid mediator of inflammation. Since its first description in 1972, it has emerged as a key regulator of vital cellular signaling functions, as proliferation, cell adhesion, and apoptosis. Evidence suggests that interactions between PAF and its receptor (PAFR) play a critical role in nervous system tissues, including the retina. The retina is a very important constituent of the visual system, along with the cornea, sclera, choroid, iris, and ciliary body, that acts synergistically to provide vision and to maintain optical homeostasis. There is evidence that PAF may regulate a wide range of physiological functions in the visual system tissues, such as eye development, inflammation, epithelial wound healing, and synapsis. Due to their multiple functions, PAF and PAFR also have important pathological and clinical implications in ocular disorders such as Choroidal Neovascularization (CNV), Age Macular Degeneration, (AMD), Diabetic Retinopathy (DR), transplant responses, and pharmacological interactions. Studies with PAFR antagonists have shown promising results such as inhibition of neovascularization and chloroquine-induced retinopathies, as well as reducing inflammation and retinal cell death. Due to the importance of PAFR signaling in the visual system and ophthalmology research, this review aims to provide a general overview of current and future perspectives about PAF in eye biology.

Superior Neuroprotective Efficacy of LAU-0901, a Novel Platelet-Activating Factor Antagonist, in Experimental Stroke

Platelet-activating factor (PAF) accumulates during cerebral ischemia, and inhibition of this process plays a critical role in neuronal survival. Recently, we demonstrated that LAU-0901, a novel PAF receptor antagonist, is neuroprotective in experimental stroke. We used magnetic resonance imaging in conjunction with behavior and immunohistopathology to expand our understanding of this novel therapeutic approach. Sprague–Dawley rats received 2 h middle cerebral artery occlusion (MCAo) and were treated with LAU-0901 (60 mg/kg) or vehicle 2 h from MCAo onset. Behavioral function, T2-weighted imaging (T2WI), and apparent diffusion coefficients were performed on days 1, 3, and 7 after MCAo. Infarct volume and number of GFAP, ED-1, and NeuN-positive cells were conducted on day 7. Behavioral deficit was significantly improved by LAU-0901 treatment compared to vehicle on days 1, 3, and 7. Total lesion volumes computed from T2WI were significantly reduced by LAU-0901 on days 1, 3, and 7 (by 83%, 90%, and 96%, respectively), which was consistent with decreased edema formation. Histopathology revealed that LAU-0901 treatment resulted in significant reduction of cortical and subcortical infarct volumes, attenuated microglial infiltration, and promoted astrocytic and neuronal survival. These findings suggest LAU-0901 is a promising neuroprotectant and provide the basis for future therapeutics in patients suffering ischemic stroke.

Resolvin E1 improves tear production and decreases inflammation in a dry eye mouse model

PURPOSE

Dry eye (DE) is a common ocular surface disease, particularly among women and the elderly, with chronic symptoms of eye irritation and, in severe cases, blurred vision. Several studies have shown that there is an inflammatory component in DE, although the pathogenesis is not thoroughly understood. Resolvin E1 (RvE1; RX-10001) is an endogenous mediator derived from the omega-3 polyunsaturated fatty acid eicosapentaenoic acid and is involved in inflammation resolution and tissue protection. Here we investigated the role of RvE1 in a DE mouse model.

METHODS

Thirteen- to 14-week-old female BALB/C mice were exposed to desiccating conditions. One week after DE exposure, animals were treated topically with drug or vehicle 4 times per day for an additional week. Controls were nontreated animals placed in a normal environment. Schirmer's test was performed before treatment initiation and at days 2 and 4 after treatment. Density of corneal epithelial cells was analyzed in vivo using the Rostock Cornea Module of the Heidelberg Retina Tomograph (HRT-II). Corneas were processed using Western blot analysis and immunofluorescence examination.

RESULTS

Schirmer's test showed a significant decrease in tear production in DE compared with controls. There was no change at 2 and 4 days after treatment with the vehicle, but a significant increase was observed at 2 and 4 days in the RvE1-treated group. The density of the superficial epithelial cells showed a significant decrease after DE compared with controls, which increased after 7 days of RvE1 treatment. Western blot analysis showed that α-smooth muscle actin and cyclooxygenase-2 (COX-2) expression were strongly upregulated after DE and decreased after 7 days of RvE1 treatment. Immunofluorescence confirmed strong positive staining of α-smooth muscle actin and COX-2 in stroma and/or in epithelia after DE, which decreased with RvE1 treatment. The percentage of infiltrating CD⁴+ T cells and CD11b+ cells decreased after RvE1 treatment when compared with DE.

CONCLUSION

RvE1 promotes tear production, corneal epithelial integrity, and a decrease in inflammatory inducible COX-2. In the stroma, RvE1 inhibits keratocyte transformation to myofibroblasts and lowers the number of monocytes/macrophages in this DE mouse model. These results suggest that RvE1 and similar resolvin analogs have therapeutic potential in the treatment of DE.