Identification and pharmacological characterization of the prostaglandin FP receptor and FP receptor variant complexes

New role for the anandamide metabolite prostaglandin F2α ethanolamide: Rolling preadipocyte proliferation

White adipose tissue regulation is key to metabolic health, yet still perplexing. The chief endocannabinoid anandamide metabolite, prostaglandin F2α ethanolamide (PGF2αEA), inhibits adipogenesis, that is, the formation of mature adipocytes. We observed that adipocyte progenitor cells-preadipocytes-following treatment with PGF2αEA yielded larger pellet sizes. Thus, we hypothesized that PGF2αEA might augment preadipocyte proliferation. Cell viability MTT and crystal violet assays, cell counting, and 5-bromo-2'-deoxyuridine incorporation in cell proliferation ELISA analyses confirmed our prediction. Additionally, we discovered that PGF2αEA promotes cell cycle progression through suppression of the expression of cell cycle inhibitors, p21 and p27, as shown by flow cytometry and qPCR. Enticingly, concentrations of this compound that showed no visible effect on cell proliferation or basal transcriptional activity of peroxisome proliferator-activated receptor gamma could, in contrast, reverse the anti-proliferative and peroxisome proliferator-activated receptor gamma-transcription activating effects of rosiglitazone (Rosi). MTT and luciferase reporter examinations supported this finding. The PGF2αEA pharmaceutical analog, bimatoprost, was also investigated and showed very similar effects. Importantly, we suggest the implication of the mitogen-activated protein kinase pathway in these effects, as they were blocked by the selective mitogen-activated protein kinase kinase inhibitor, PD98059. We propose that PGF2αEA is a pivotal regulator of white adipose tissue plasticity, acting as a regulator of the preadipocyte pool in adipose tissue.

Genotype and Phenotype Influence the Personal Response to Prostaglandin Analogues and Beta-Blockers in Spanish Glaucoma and Ocular Hypertension Patients

Analysis of the genotype that predicts the phenotypic characteristics of a cohort of glaucoma and ocular hypertension patients, and the correlation with their personal pharmacological response to beta-blockers (BB) and prostaglandin analogues (PGA). Prospective study that included 139 eyes from 72 patients under BB and/or PGA treatment, and in some cases other types of ocular hypotensive treatments. Five single-nucleotide polymorphisms were genotyped by real-time PCR assays: prostaglandin-F2α receptor (rs3766355, rs3753380); cytochrome-P450 2D6 (rs16947, rs769258); and beta-2-adrenergic receptor (rs1042714). Other studied variables were mean deviation (MD) of visual field, previous ocular interventions, medical treatment, baseline (bIOP), and treated intraocular pressure (tIOP). From a total of 139 eyes, 71 (51.1%) were left eyes. The main diagnosis was primary open angle glaucoma (66.2%). A total of 57 (41%) eyes were under three or more medications (PGA + BB + other) and, additionally, 57 eyes (41%) had had some kind of glaucoma surgery. The mean bIOP and tIOP were 26.55 ± 8.19 and 21.01 ± 5.54 mmHg, respectively. Significant differences in tIOP were found between heterozygous (HT) (21.07 ± 0.607 mmHg) and homozygous (HM) (20.98 ± 0.639 mmHg) rs3766355 with respect to wildtype individuals (16 ± 1.08 mmHg) (p = 0.031). The MD values presented significant differences between wildtype rs3766355 (-2 ± 2.2 dB), HT (-3.87 ± 4 dB), and HM carriers (-9.37 ± 9.51 dB) (p = 0.009). Significant differences were also observed between the MD in wildtype rs3753380 (-6.1 ± 8.67 dB), HT (-9.02 ± 8.63 dB), and HM carriers (-9.51 ± 7.44 dB) (p = 0.017). Patients carrying the variant rs3766355 in HM or HT presented clinically-significantly higher tIOP than wildtype patients. Additionally, some differences in MD were found in rs3766355 and rs3753380 carriers, and the more alleles that were affected, the worse the MD value, meaning greater severity of the glaucoma. Poor response to treatment and more visual field damage may be associated with being a carrier of these mutated alleles.

Anandamide and other N-acylethanolamines: A class of signaling lipids with therapeutic opportunities

N-acylethanolamines (NAEs), including N-palmitoylethanolamine (PEA), N-oleoylethanolamine (OEA), N-arachidonoylethanolamine (AEA, anandamide), N-docosahexaenoylethanolamine (DHEA, synaptamide) and their oxygenated metabolites are a lipid messenger family with numerous functions in health and disease, including inflammation, anxiety and energy metabolism. The NAEs exert their signaling role through activation of various G protein-coupled receptors (cannabinoid CB₁ and CB₂ receptors, GPR55, GPR110, GPR119), ion channels (TRPV1) and nuclear receptors (PPAR-α and PPAR-γ) in the brain and periphery. The biological role of the oxygenated NAEs, such as prostamides, hydroxylated anandamide and DHEA derivatives, are less studied. Evidence is accumulating that NAEs and their oxidative metabolites may be aberrantly regulated or are associated with disease severity in obesity, metabolic syndrome, cancer, neuroinflammation and liver cirrhosis. Here, we comprehensively review NAE biosynthesis and degradation, their metabolism by lipoxygenases, cyclooxygenases and cytochrome P450s and the biological functions of these signaling lipids. We discuss the latest findings and therapeutic potential of modulating endogenous NAE levels by inhibition of their degradation, which is currently under clinical evaluation for neuropsychiatric disorders. We also highlight NAE biosynthesis inhibition as an emerging topic with therapeutic opportunities in endocannabinoid and NAE signaling.

Bimatoprost promotes satiety and attenuates body weight gain in rats fed standard or obesity-promoting diets

Bimatoprost is a synthetic prostamide F_2α analog that down-regulates adipogenesis in vitro. This effect has been attributed to participation in a negative feedback loop that regulates anandamide-induced adipogenesis. A follow-on investigation has now been conducted into the broader metabolic effects of bimatoprost using rats under both normal state and obesity-inducing conditions. Chronic bimatoprost administration attenuated weight gain in a dose dependent-manner in rats fed either standard [max effect -7%] or obesity-promoting diets [max effect -23%] over a 9-10 week period. Consistent with these findings, bimatoprost promoted satiety as measured by decreased food intake [max effect, -7%], gastric emptying [max effect, -33-50%] and decreased circulating concentrations of the gut hormones, ghrelin and GLP-1 [max effect, -33-50%]. Additionally, subcutaneous, and visceral fat mass were distinctly affected by treatment [-30% diet independent]. Taken together, these results suggest that bimatoprost regulates energy homeostasis through promoting satiety and a decrease in food intake. These newly reported activities of bimatoprost reveal an additional method of metabolic disease intervention for potential therapeutic exploitation.

Biosynthesis and metabolism of endocannabinoids and their congeners from the monoacylglycerol andN-acyl-ethanolamine families

The endocannabinoids 2-arachidonoyl-glycerol (2-AG) and N-arachidonoyl-ethanolamine (AEA) are eicosanoids implicated in numerous physiological processes like appetite, adipogenesis, inflammatory pain and inflammation. They mediate most of their physiological effect by activating the cannabinoid (CB) receptors 1 and 2. Other than directly binding to the CB receptors, 2-AG and AEA are also metabolized by most eicosanoid biosynthetic enzymes, yielding many metabolites that are part of the oxyendocannabinoidome. Some of these metabolites have been found in vivo, have the ability to modulate specific receptors and thus potentially influence physiological processes. In this review, we discuss the biosynthesis and metabolism of 2-AG and AEA, as well as their congeners from the monoacyl-glycerol and N-acyl-ethanolamine families, with a special focus on the metabolism by oxygenases involved in arachidonic acid metabolism. We highlight the knowledge gaps in our understanding of the regulation and roles the oxyendocannabinoidome mediators.

[Prospects of the use of prostaglandin analogues in the treatment of patients with thyroid eye disease]

Currently, the only effective method of treatment and rehabilitation of patients with inactive thyroid eye disease (TED) is orbital decompression. This review analyzes the prospects of using prostaglandin analogues (PGF2β) to decrease the volume of orbital fat in order to reduce proptosis and periorbital changes in TED. Despite the fact that the available data on the results of using PGF2β analogues in patients with TED are contradictory, were based on short follow-up periods and involved only a small number of patients, we believe that this topic is a very promising avenue for further research.

Deletion of the gene encoding prostamide/prostaglandin F synthase reveals an important role in regulating intraocular pressure

Prostamide/prostaglandin F synthase (PM/PGFS) is an enzyme with very narrow substrate specificity and is dedicated to the biosynthesis of prostamide F_2α and prostaglandin F_2α (PGF_2α.). The importance of this enzyme, relative to the aldo-keto reductase (AKR) series, in providing functional tissue prostamide F_2α levels was determined by creating a line of PM/PGFS gene deleted mice. Deletion of the gene encoding PM/PGFS (Fam213b / Prxl2b) was accomplished by a two exon disruption. Prostamide F_2α levels in wild type (WT) and PM/PGFS knock-out (KO) mice were determined by LC/MS/MS. Deletion of Fam213b (Prxl2b) had no observed effect on behavior, appetite, or fertility. In contrast, tonometrically measured intraocular pressure was significantly elevated by approximately 4 mmHg in PM/PGFS KO mice compared to littermate WT mice. Outflow facility was measured in enucleated mouse eyes using the iPerfusion system. No effect on pressure dependent outflow facility occurred, which is consistent with the effects of prostamide F_2α and PGF_2α increasing outflow through the unconventional pathway. The elevation of intraocular pressure caused by deletion of the gene encoding the PM/PGFS enzyme likely results from a diversion of the endoperoxide precursor pathway to provide increased levels of those prostanoids known to raise intraocular pressure, namely prostaglandin D₂ (PGD₂) and thromboxane A₂ (TxA₂). It follows that PM/PGFS may serve an important regulatory role in the eye by providing PGF_2α and prostamide F_2α to constrain the influence of those prostanoids that raise intraocular pressure.

Druggable Targets in Endocannabinoid Signaling

Cannabis and cannabinoid-based extracts have long been utilized for their perceived therapeutic value, and support for the legalization of cannabis for medicinal purposes continues to increase worldwide. Since the discovery of Δ⁹-tetrahydrocannabinol (THC) as the primary psychoactive component of cannabis over 50 years ago, substantial effort has been directed toward detection of endogenous mediators of cannabinoid activity. The discovery of anandamide and 2-arachidonoylglycerol as two endogenous lipid mediators of cannabinoid-like effects (endocannabinoids) has inspired exponential growth in our understanding of this essential pathway, as well as the pathological conditions that result from dysregulated endocannabinoid signaling. This review examines current knowledge of the endocannabinoid system including metabolic enzymes involved in biosynthesis and degradation and their receptors, and evaluates potential druggable targets for therapeutic intervention.

A Review of Prostanoid Receptors: Expression, Characterization, Regulation, and Mechanism of Action

Prostaglandin signaling controls a wide range of biological processes from blood pressure homeostasis to inflammation and resolution thereof to the perception of pain to cell survival. Disruption of normal prostanoid signaling is implicated in numerous disease states. Prostaglandin signaling is facilitated by G-protein-coupled, prostanoid-specific receptors and the array of associated G-proteins. This review focuses on the expression, characterization, regulation, and mechanism of action of prostanoid receptors with particular emphasis on human isoforms.

Prostaglandin F2α agonist-induced suppression of 3T3-L1 cell adipogenesis affects spatial formation of extra-cellular matrix

To establish a deepening of the upper eyelid sulcus (DUES) model that can be induced by prostaglandin (PG) analogues, a three-dimension (3D) tissue culture was employed. Upon adipogenesis of the 3T3-L1 organoid, the effects of either Bimatoprost acid (BIM-A), or PGF2α were examined. During the adipogenesis, organoid size, lipid staining by BODIPY and expression of the extracellular matrix (ECM) by immunocytochemistry and/or quantitative PCR were employed. The size of the organoid increased remarkably during the adipogenesis, while such increases were significantly inhibited by the presence of PGF2α or BIM-A. BODIPY positive lipid-laden cells significantly increased during the adipogenesis, while in contrast they were greatly suppressed by the presence of PGF2α. Characteristic and spatial changes in ECM expressions observed upon adipogenesis were greatly modified by the presence of PGs. Our present study using a 3D tissue culture may be a suitable strategy toward understanding disease etiology of DUES.

Matrix Metalloproteinases and Glaucoma Treatment

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade extracellular matrix (ECM) components such as collagen and have important roles in multiple biological processes, including development and tissue remodeling, both in health and disease. The activity of MMPs is influenced by the expression of MMPs and tissue inhibitors of metalloproteinase (TIMPs). In the eye, MMP-mediated ECM turnover in the juxtacanalicular region of the trabecular meshwork (TM) reduces outflow resistance in the conventional outflow pathway and helps maintain intraocular pressure (IOP) homeostasis. An imbalance in the MMP/TIMP ratio may be involved in the elevated IOP often associated with glaucoma. The prostaglandin analog/prostamide (PGA) class of topical ocular hypotensive medications used in glaucoma treatment reduces IOP by increasing outflow through both conventional and unconventional (uveoscleral) outflow pathways. Evidence from in vivo and in vitro studies using animal models and anterior segment explant and cell cultures indicates that the mechanism of IOP lowering by PGAs involves increased MMP expression in the TM and ciliary body, leading to tissue remodeling that enhances conventional and unconventional outflow. PGA effects on MMP expression are dependent on the identity and concentration of the PGA. An intracameral sustained-release PGA implant (Bimatoprost SR) in development for glaucoma treatment can reduce IOP for many months after expected intraocular drug bioavailability. We hypothesize that the higher concentrations of bimatoprost achieved in ocular outflow tissues with the implant produce greater MMP upregulation and more extensive, sustained MMP-mediated target tissue remodeling, providing an extended duration of effect.

Antiglaucoma EP2 Agonists: A Long Road That Led Somewhere

For >2 decades, EP₂ agonists have been the subject of antiglaucoma research and development by scientists in industry and academia around the world. The road has led to the recent approval of the first drug of this class. This article reviews the development of EP₂ agonists from conception to clinical approval, discussing pharmacology, structure, biodistribution, therapeutics, and drug delivery. An extensive list of source references is provided for the reader's benefit.

The Effect of Prostaglandin Analogue Bimatoprost on Thyroid-Associated Orbitopathy

Purpose

We characterize the effect of bimatoprost on orbital adipose tissue in thyroid-associated orbitopathy (TAO) with clinicopathologic correlation.

Methods

Orbital adipose-derived stem cells (OASCs) from types 1 and 2 TAO and control patients with and without exposure to 1 μm bimatoprost were examined via immunohistochemistry, RT-PCR, and Western blot for cell viability, migration capacity, lipid content, adipocyte morphology, mitochondrial content, and levels of adipogenic markers. A retrospective chart review was performed for clinicopathologic correlation. In mice, optical coherence tomography and pattern electroretinography were performed at baseline and at 1 month following a retrobulbar injection of bimatoprost, followed by orbital exenteration for histopathologic examination.

Results

Types 1 and 2 TAO-derived cells had a significantly higher migration capacity and lipid content than those of healthy controls. With the addition of bimatoprost, types 1 and 2 TAO and control adipocytes exhibited a significant decrease in lipid content with morphologic transformation into smaller and multilocular lipid droplets, and an increase in mitochondrial load and UCP-1 expression consistent with an increase in brown adipose tissue turnover. Retrobulbar injection of bimatoprost in mice did not alter the gross morphology, retinal thickness, or ganglion cell function in vivo.

Conclusions

Bimatoprost inhibits adipogenesis in OASCs and upregulates pathways involved in the browning of adipocytes. Furthermore, retrobulbar injection of bimatoprost is tolerated without immediate adverse effects in mice. Our results suggest a potential future application of prostaglandin analogues in the treatment of TAO.

Prostaglandin D2-ethanolamide induces skin cancer apoptosis by suppressing the activity of cellular antioxidants

The combined incidence of melanoma and non-melanoma skin cancer (NMSC) is greater than the incidence of all other malignancies in the US. Previously, we demonstrated that the endocannabinoid, arachidonoyl-ethanolamide (AEA), was a potent inducer of apoptosis in NMSC. The metabolism of AEA to the prostaglandin, PGD₂-EA, was a prerequisite for AEA cytotoxicity. However, the mechanism of PGD₂-EA cell death has not been clearly defined. In the present study, we report that PGD₂-EA causes apoptosis in melanoma and NMSC cells. Mass spectrometry analysis revealed that PGD₂-EA was dehydrated to three J-series prostaglandins; PGJ₂-EA, Δ¹²PGJ₂-EA, and 15deoxy,Δ12,14 PGJ₂-EA. PGD₂-EA inhibited the antioxidant activity of glutathione and thioredoxin which then caused oxidative stress. This increase in oxidative stress was accompanied by the activation of endoplasmic reticulum (ER) stress and apoptosis. The effect of PGD₂-EA was independent of DP1, DP2, and PPARγ receptors suggesting that PGD₂-EA cytotoxicity was mediated by its metabolic product, 15dPGJ₂-EA.

Ocular hypotensive effects of prostaglandin analogs in Japanese patients with normal-tension glaucoma: a literature review

PURPOSE

This paper aimed to evaluate the intraocular pressure (IOP)-lowering effects of prostaglandin analogs (PGAs) in Japanese patients with normal-tension glaucoma (NTG) by reviewing the current literature.

METHODS

In February 2018, database searches were performed in PubMed, Embase, ProQuest, and the Japanese databases JAPICDOC and JMEDPlus. Studies were sorted into two categories: Category 1 consisted of studies of patients with NTG who reported reduced IOP values and Category 2 consisted of studies of patients with NTG who had IOP values at predosing and a final evaluation point. Search terms included ([unoprostone or latanoprost or travoprost or bimatoprost or tafluprost] and [glaucoma] and [Japan or Japanese]). The weighted ocular hypotensive efficacy was calculated. A scatter plot analysis was performed and a regression equation was calculated for each medication. The fitting of each regression equation was evaluated by the least squares method.

RESULTS

Eleven articles were eligible for Category 1 and 25 articles for Category 2. In the rank order of IOP-lowering efficacy of PGAs, bimatoprost was the strongest and latanoprost the weakest. Travoprost and tafluprost had almost the same level of ocular hypotensive effect, and both were stronger than latanoprost. The scatter plot analysis showed that all PGAs reduced IOP by 15%-20%. At higher IOP (17-18 mmHg), the ocular hypotensive effect was almost the same with latanoprost, travoprost, and tafluprost. In contrast, at lower IOP (12-15 mmHg), the IOP reduction with latanoprost was weaker than with travoprost or tafluprost.

CONCLUSION

This literature review of the ocular hypotensive effects of PGAs in Japanese patients with NTG highlighted that PGAs had different ocular hypotensive effects. Ophthalmologists should understand the IOP-lowering profiles of various PGAs and apply them to patients with NTG on a case-by-case basis.

TRIAL REGISTRATION

UMIN Clinical Trials Registry UMIN000032344.

Synthesis and Evaluation of the Novel Prostamide, 15-Deoxy, Δ12,14-Prostamide J2, as a Selective Antitumor Therapeutic

15-deoxy, Δ^12,14-prostaglandin J₂-ethanolamide, also known as 15-deoxy, Δ^12,14-prostamide J₂ (15d-PMJ₂) is a novel product of the metabolism of arachidonoyl ethanolamide (AEA) by COX-2. 15d-PMJ₂ preferentially induced cell death and apoptosis in tumorigenic A431 keratinocytes and B16F10 melanoma cells compared with nontumorigenic HaCaT keratinocytes and Melan-A melanocytes. Activation of the ER stress execution proteins, PERK and CHOP10, was evaluated to determine whether this process was involved in 15d-PMJ₂ cell death. 15d-PMJ₂ increased the phosphorylation of PERK and expression of CHOP10 in tumorigenic but not nontumorigenic cells. The known ER stress inhibitors, salubrinal and 4-phenylbutaric acid, significantly inhibited 15d-PMJ₂-mediated apoptosis, suggesting ER stress as a primary apoptotic mediator. Furthermore, the reactive double bond present within the cyclopentenone structure of 15d-PMJ₂ was identified as a required moiety for the induction of ER stress apoptosis. The effect of 15d-PMJ₂ on B16F10 melanoma growth was also evaluated by dosing C57BL/6 mice with 0.5 mg/kg 15d-PMJ₂ Tumors of animals treated with 15d-PMJ₂ exhibited significantly reduced growth and mean weights compared with vehicle and untreated animals. TUNEL and IHC analysis of tumor tissues showed significant cell death and ER stress in tumors of 15d-PMJ₂-treated compared with control group animals. Taken together, these findings suggest that the novel prostamide, 15d-PMJ₂, possesses potent antitumor activity in vitro and in vivoMol Cancer Ther; 16(5); 838-49. ©2017 AACR.

The Endocannabinoid System as a Therapeutic Target in Glaucoma

Glaucoma is an irreversible blinding eye disease which produces progressive retinal ganglion cell (RGC) loss. Intraocular pressure (IOP) is currently the only modifiable risk factor, and lowering IOP results in reduced risk of progression of the disorder. The endocannabinoid system (ECS) has attracted considerable attention as a potential target for the treatment of glaucoma, largely due to the observed IOP lowering effects seen after administration of exogenous cannabinoids. However, recent evidence has suggested that modulation of the ECS may also be neuroprotective. This paper will review the use of cannabinoids in glaucoma, presenting pertinent information regarding the pathophysiology of glaucoma and how alterations in cannabinoid signalling may contribute to glaucoma pathology. Additionally, the mechanisms and potential for the use of cannabinoids and other novel agents that target the endocannabinoid system in the treatment of glaucoma will be discussed.

Fixed-combination treatments for intraocular hypertension in Chinese patients - focus on bimatoprost-timolol

Glaucoma is a common eye disease that can lead to irreversible vision loss if left untreated. The early diagnosis and treatment of primary open-angle glaucoma is challenging, and visual impairment in Chinese glaucoma patients is a serious concern. Most of these patients need more than one topical antiglaucoma agent to control their intraocular pressures (IOPs). In the People’s Republic of China, the daily cost of different glaucoma medication varies greatly, and the treatment habits differ throughout the country. Prostaglandin analogs (PGAs) are recommended as first-line monotherapy, because of their efficacy and low risk of systemic side effects. Fixed-combination drops, particularly PGA-based fixed combinations, have recently been developed and used in patients with progression or who have failed to achieve their target IOPs. Here, we reviewed the current literature on the use of bimatoprost-timolol fixed combination (BTFC) in the People’s Republic of China. BTFC has achieved good efficacy and tolerability in Chinese clinical trials. In addition, BTFC is more cost effective compared with other fixed combinations available in the People’s Republic of China. Fixed-combination drops may offer benefits, such as keeping the ocular surface healthy, convenience of administration, and improvement in long-term adherence and quality of life. Therefore, BTFC has great potential for the treatment of Chinese glaucoma patients. However, the long-term efficacy of BTFC, comparisons of BTFC with other fixed-combination drugs, and treatment adherence and persistence with treatment in Chinese patients are unknown and will require further study.

4'-O-methylhonokiol increases levels of 2-arachidonoyl glycerol in mouse brain via selective inhibition of its COX-2-mediated oxygenation

BACKGROUND AND PURPOSE

4'-O-methylhonokiol (MH) is a natural product showing anti-inflammatory, anti-osteoclastogenic, and neuroprotective effects. MH was reported to modulate cannabinoid CB2 receptors as an inverse agonist for cAMP production and an agonist for intracellular [Ca2+]. It was recently shown that MH inhibits cAMP formation via CB2 receptors. In this study, the exact modulation of MH on CB2 receptor activity was elucidated and its endocannabinoid substrate-specific inhibition (SSI) of cyclooxygenase-2 (COX-2) and CNS bioavailability are described for the first time.

METHODS

CB2 receptor modulation ([35S]GTPγS, cAMP, and β-arrestin) by MH was measured in hCB2-transfected CHO-K1 cells and native conditions (HL60 cells and mouse spleen). The COX-2 SSI was investigated in RAW264.7 cells and in Swiss albino mice by targeted metabolomics using LC-MS/MS.

RESULTS

MH is a CB2 receptor agonist and a potent COX-2 SSI. It induced partial agonism in both the [35S]GTPγS binding and β-arrestin recruitment assays while being a full agonist in the cAMP pathway. MH selectively inhibited PGE2 glycerol ester formation (over PGE2) in RAW264.7 cells and significantly increased the levels of 2-AG in mouse brain in a dose-dependent manner (3 to 20 mg kg(-1)) without affecting other metabolites. After 7 h from intraperitoneal (i.p.) injection, MH was quantified in significant amounts in the brain (corresponding to 200 to 300 nM).

CONCLUSIONS

LC-MS/MS quantification shows that MH is bioavailable to the brain and under condition of inflammation exerts significant indirect effects on 2-AG levels. The biphenyl scaffold might serve as valuable source of dual CB2 receptor modulators and COX-2 SSIs as demonstrated by additional MH analogs that show similar effects. The combination of CB2 agonism and COX-2 SSI offers a yet unexplored polypharmacology with expected synergistic effects in neuroinflammatory diseases, thus providing a rationale for the diverse neuroprotective effects reported for MH in animal models.

The impact of timolol maleate on the ocular tolerability of fixed-combination glaucoma therapies

Glaucomatous optic atrophy is the second most common cause of blindness worldwide, and lowering intraocular pressure (IOP) is the only proven method to slow or stop the progression of the disease. Approximately 40% of patients with elevated IOP will require more than one medication to obtain a modest 20% reduction in IOP, and as a result, some patients may require two medications, provided in either two separate bottles or in one bottle with the use of fixed-combination therapies. Each therapy has its own unique safety and efficacy profile. Topical beta-blockers have a particularly favorable ocular-tolerability profile, and several studies of fixed-combination medications containing the beta-blocker timolol maleate have shown a lower prevalence of some ocular adverse events for the fixed-combination therapy compared to the non-beta-blocker individual component. In this review, we examined clinical data pertaining to the ocular surface tolerability of fixed-combination medications containing timolol maleate in comparison to the individual components. In particular, preference was given to prospective, randomized, multicenter trials of 3 months in duration or longer that compared a fixed-combination therapy to monotherapy with the individual components. A review of the literature revealed that some fixed-combination therapies can provide a reduced risk of common side effects compared to their individual components, with conjunctival hyperemia and ocular allergy being less frequent in some timolol-containing fixed-combination therapies. This effect appears to be most significant for latanoprost 0.005%, bimatoprost 0.03%, and brimonidine 0.2%.

Functionalization of β-caryophyllene generates novel polypharmacology in the endocannabinoid system

The widespread dietary plant sesquiterpene hydrocarbon β-caryophyllene (1) is a CB2 cannabinoid receptor-specific agonist showing anti-inflammatory and analgesic effects in vivo. Structural insights into the pharmacophore of this hydrocarbon, which lacks functional groups other than double bonds, are missing. A structure-activity study provided evidence for the existence of a well-defined sesquiterpene hydrocarbon binding site in CB2 receptors, highlighting its exquisite sensitivity to modifications of the strained endocyclic double bond of 1. While most changes on this element were detrimental for activity, ring-opening cross metathesis of 1 with ethyl acrylate followed by amide functionalization generated a series of new monocyclic amides (11a, 11b, 11c) that not only retained the CB2 receptor functional agonism of 1 but also reversibly inhibited fatty acid amide hydrolase (FAAH), the major endocannabinoid degrading enzyme, without affecting monoacylglycerol lipase (MAGL) and α,β hydrolases 6 and 12. Intriguingly, further modification of this monocyclic scaffold generated the FAAH- and endocannabinoid substrate-specific cyclooxygenase-2 (COX-2) dual inhibitors 11e and 11f, which are probes with a novel pharmacological profile. Our study shows that by removing the conformational constraints induced by the medium-sized ring and by introducing functional groups in the sesquiterpene hydrocarbon 1, a new scaffold with pronounced polypharmacological features within the endocannabinoid system could be generated. The structural and functional repertoire of cannabimimetics and their yet poorly understood intrinsic promiscuity may be exploited to generate novel probes and ultimately more effective drugs.

Substrate-selective COX-2 inhibition as a novel strategy for therapeutic endocannabinoid augmentation

Pharmacologic augmentation of endogenous cannabinoid (eCB) signaling is an emerging therapeutic approach for the treatment of a broad range of pathophysiological conditions. Thus far, pharmacological approaches have focused on inhibition of the canonical eCB inactivation pathways - fatty acid amide hydrolase (FAAH) for anandamide and monoacylglycerol lipase (MAGL) for 2-arachidonoylglycerol. We review here the experimental evidence that cyclooxygenase-2 (COX-2)-mediated eCB oxygenation represents a third mechanism for terminating eCB action at cannabinoid receptors. We describe the development, molecular mechanisms, and in vivo validation of 'substrate-selective' COX-2 inhibitors (SSCIs) that prevent eCB inactivation by COX-2 without affecting prostaglandin (PG) generation from arachidonic acid (AA). Lastly, we review recent data on the potential therapeutic applications of SSCIs with a focus on neuropsychiatric disorders.

Heterodimerization of mouse orexin type 2 receptor variants and the effects on signal transduction

Orexin-A and Orexin-B play important roles in many physiological processes in which Orexins orchestrate diverse downstream effects via two G-protein coupled receptors: Orexin1R and Orexin2R. Two alternative C-terminus splice variants of the mouse Orexin receptors mOX2alphaR and mOX2betaR have recently been identified. This study explored the possibility of heterodimerization between mOX2alphaR and mOX2betaR, and investigated novel signal transduction characteristics after stimulation. The dimerization of mOX2alphaR and mOX2betaR was confirmed by BRET and co-immunoprecipitation assays. Meanwhile, in HEK293 cells, co-expression of mOX2alphaR and mOX2betaR resulted in a strengthened increase in activation of ERK1/2, with maximal activation at 5 min and 100 nM. Furthermore, heterodimerization also elicits stronger intracellular Ca2+ elevation after Orexin(s) stimulation, followed by a slower decline in intracellular Ca2+ to a steady endpoint Protein Kinase C Inhibitor significantly inhibited these downstream effects. In addition, the cAMP response element reporter activities were significantly reduced, whereas the serum response element luciferase and the T-lymphocyte activation of nuclear factor-responsive element reporter activity were significantly up-regulated after Orexin(s) stimulation. Besides, Orexin-A/-B induced a significantly higher rate of HEK293 cell proliferation in cells co-expressing mOX2alphaR/mOX2betaR compared to the control group. Taken together, we provide conclusive evidence that mOX2alphaR can form a functional heterodimer with mOX2betaR and this leads to increased PKC and decreased protein kinase A activity by ERK signal pathway leading to a significant increase in cell proliferation. The nature of this signaling pathway has significant implications for the role of Orexin in the regulation of physiological processes including the homeostasis of feeding.

Bimatoprost-loaded ocular inserts as sustained release drug delivery systems for glaucoma treatment: in vitro and in vivo evaluation

The purpose of the present study was to develop and assess a novel sustained-release drug delivery system of Bimatoprost (BIM). Chitosan polymeric inserts were prepared using the solvent casting method and characterized by swelling studies, infrared spectroscopy, differential scanning calorimetry, drug content, scanning electron microscopy and in vitro drug release. Biodistribution of ^99mTc-BIM eye drops and ^99mTc-BIM-loaded inserts, after ocular administration in Wistar rats, was accessed by ex vivo radiation counting. The inserts were evaluated for their therapeutic efficacy in glaucomatous Wistar rats. Glaucoma was induced by weekly intracameral injection of hyaluronic acid. BIM-loaded inserts (equivalent to 9.0 µg BIM) were administered once into conjunctival sac, after ocular hypertension confirmation. BIM eye drop was topically instilled in a second group of glaucomatous rats for 15 days days, while placebo inserts were administered once in a third group. An untreated glaucomatous group was used as control. Intraocular pressure (IOP) was monitored for four consecutive weeks after treatment began. At the end of the experiment, retinal ganglion cells and optic nerve head cupping were evaluated in the histological eye sections. Characterization results revealed that the drug physically interacted, but did not chemically react with the polymeric matrix. Inserts sustainedly released BIM in vitro during 8 hours. Biodistribution studies showed that the amount of ^99mTc-BIM that remained in the eye was significantly lower after eye drop instillation than after chitosan insert implantation. BIM-loaded inserts lowered IOP for 4 weeks, after one application, while IOP values remained significantly high for the placebo and untreated groups. Eye drops were only effective during the daily treatment period. IOP results were reflected in RGC counting and optic nerve head cupping damage. BIM-loaded inserts provided sustained release of BIM and seem to be a promising system for glaucoma management.

Prostamide F(2) α receptor antagonism combined with inhibition of FAAH may block the pro-inflammatory mediators formed following selective FAAH inhibition

BACKGROUND AND PURPOSE

Prostamides are lipid mediators formed by COX-2-catalysed oxidation of the endocannabinoid anandamide and eliciting effects often opposed to those caused by anandamide. Prostamides may be formed when hydrolysis of anandamide by fatty acid amide hydrolase (FAAH) is physiologically, pathologically or pharmacologically decreased. Thus, therapeutic benefits of FAAH inhibitors might be attenuated by concomitant production of prostamide F2 α . This loss of benefit might be minimized by compounds designed to selectively antagonize prostamide receptors and also inhibiting FAAH.

EXPERIMENTAL APPROACH

Inhibition of FAAH by a series of selective antagonists of prostamide receptors, including AGN 204396, AGN 211335 and AGN 211336, was assessed using rat, mouse and human FAAH in vitro, together with affinity for human recombinant CB1 and CB2 receptors. Effects in vivo were measured in a model of formalin-induced inflammatory pain in mice.

KEY RESULTS

The prostamide F2 α receptor antagonists were active against mouse and rat FAAH in the low μM range and behaved as non-competitive and plasma membrane-permeant inhibitors. AGN 211335, the most potent inhibitor of rat FAAH (IC50  = 1.2 μM), raised exogenous anandamide levels in intact cells and also bound to cannabinoid CB1 receptors. Both AGN 211335 and AGN 211336 (0.25-1 mg·kg(-1) , i.p.) inhibited the formalin-induced nociceptive response in mice.

CONCLUSIONS AND IMPLICATIONS

Synthetic compounds with indirect agonist activity at cannabinoid receptors and antagonist activity at prostamide receptors can be developed. Such compounds could be used as alternatives to selective FAAH inhibitors to prevent the possibility of prostamide F2 α -induced inflammation and pain.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

Effects of prostaglandin analogues on aqueous humor outflow pathways

Elevated intraocular pressure (IOP) is the most prevalent risk factor for glaucoma. All treatments, whether surgical or pharmaceutical, are aimed at lowering IOP. Prostaglandin analogues are a first line therapy for glaucoma due to their ability to reduce IOP, once-daily dosing, efficacy, and minimal side-effect profile. Whereas prostaglandin analogues have been known to alter aqueous humor outflow through the unconventional (uveoscleral) pathway, more recent evidence suggests their action also occurs through the conventional (trabecular) pathway. Understanding how prostaglandin analogues successfully lower IOP is important, as this information may lead to the discovery of new molecular targets for future therapeutic intervention. This review explores the current understanding of prostaglandin analogue biology as it pertains to IOP reduction and improved aqueous humor outflow facility.

Recent progress in prostaglandin F2α ethanolamide (prostamide F2α) research and therapeutics

Prostamide (prostaglandin ethanolamide) research emerged from two distinct lines of research: 1) the unique pharmacology of the antiglaucoma drug bimatoprost and 2) the discovery that endocannabinoid anandamide was converted by COX-2 to a series of electrochemically neutral prostaglandin (PG) ethanolamides. Bimatoprost pharmacology was found to be virtually identical to that of prostamide F2α. The earliest studies relied on comparison of agonist potencies compared with PGF2α and synthetic prostaglandin F2α (FP) receptor agonists. The subsequent discovery of selective and potent prostamide receptor antagonists (AGN 211334-6, as shown in Fig. 3) was critical for distinguishing between prostamide and FP receptor-mediated effects. The prostamide F2α receptor was then modeled by cotransfecting the wild-type FP receptor with an mRNA splicing variant (altFP4).Bimatoprost is now used therapeutically for treating both glaucoma and eyelash hypotrichosis. Bimatoprost also stimulates hair growth in isolated human scalp hair follicles. A strong effect is also seen in mouse pelage hair, where bimatoprost essentially halves the onset of hair regrowth and the time to achieve full hair regrowth in shaved mice. Beyond glaucoma and hair growth, bimatoprost has potential for reducing fat deposition. Studies to date suggest that preadipocytes are the cellular target for bimatoprost. The discovery of the enzyme prostamide/PGF synthase was invaluable in elucidating the anatomic distribution of prostamide F2α. High expression in the central nervous system provided the impetus for later studies that described prostamide F2α as a nociceptive mediator in the spinal cord. At the translational level, bimatoprost has already provided therapeutics in two distinct areas and the use of both prostamide agonists and antagonists may provide other useful medicaments.

Differential effects of prostaglandin E2-sensitive receptors on contractility of human ocular cells that regulate conventional outflow

PURPOSE

The goal of this study was to functionally compare prostaglandin E2 (PGE2)-sensitive receptors in human primary cells involved in conventional outflow.

METHODS

The expression profile of prostaglandin (PG) receptors in primary cultures of human trabecular meshwork (TM) and Schlemm's canal (SC) cells were determined by quantitative-PCR. The functional activities of endogenous PGE2-sensitive receptors were evaluated using subtype-selective agonists and antagonists with cell impedance technology.

RESULTS

Agonist-sensitive EP1, EP2, and EP4 receptors were present in TM cells, all increasing cell stiffness (or contractility) in a dose-dependent manner. Rank order of efficacy (Emax) for agonists in TM cells were EP1 greater than EP2 greater than EP4 with EC50 1.1 μM, 0.56 μM, and 0.1 μM, respectively, and no functional EP3 receptors were found. Of the four EP receptor subtypes active in SC cells, EP1 and EP3 receptor activation increased cell stiffness, while EP2 and EP4 agonists dose-dependently decreased cell stiffness 47% and 23% with EC50 values of 170 nM and 69 nM, respectively. Consistent with these observations, the Rho kinase inhibitor Y-27632 decreased cell impedance (stiffness) of TM and SC cells (∼60%), while Rho GTPase activator thrombin caused cell impedance to increase in both cell types (168%-190%).

CONCLUSIONS

Cell impedance positively correlates with cellular stiffness/contractility. Because EP2/4 receptors caused decreased cell stiffness in SC, but not in TM cells, both receptors appear to mediate IOP lowering via changes in SC cell stiffness in the conventional outflow pathway.

Anandamide-derived prostamide F2α negatively regulates adipogenesis

Lipid mediators variedly affect adipocyte differentiation. Anandamide stimulates adipogenesis via CB1 receptors and peroxisome proliferator-activated receptor γ. Anandamide may be converted by PTGS2 (COX2) and prostaglandin F synthases, such as prostamide/prostaglandin F synthase, to prostaglandin F2α ethanolamide (PGF2αEA), of which bimatoprost is a potent synthetic analog. PGF2αEA/bimatoprost act via prostaglandin F2αFP receptor/FP alt4 splicing variant heterodimers. We investigated whether prostamide signaling occurs in preadipocytes and controls adipogenesis. Exposure of mouse 3T3-L1 or human preadipocytes to PGF2αEA/bimatoprost during early differentiation inhibits adipogenesis. PGF2αEA is produced from anandamide in preadipocytes and much less so in differentiating adipocytes, which express much less PTGS2, FP, and its alt4 splicing variant. Selective antagonism of PGF2αEA receptors counteracts prostamide effects on adipogenesis, as does inhibition of ERK1/2 phosphorylation. Selective inhibition of PGF2αEA versus prostaglandin F2α biosynthesis accelerates adipogenesis. PGF2αEA levels are reduced in the white adipose tissue of high fat diet-fed mice where there is a high requirement for new adipocytes. Prostamides also inhibit zebrafish larval adipogenesis in vivo. We propose that prostamide signaling in preadipocytes is a novel anandamide-derived antiadipogenic mechanism.

Bimatoprost protects retinal neuronal damage via Akt pathway

Worldwide, prostaglandin analogs, such as bimatoprost, have become the major therapeutic class for medical treatment of glaucoma because of their efficacy and generally well tolerated systemic safety profile. However, the detailed mechanism of the direct action of bimatoprost on retinal ganglion cells (RGC) has rarely been understood. Thus, in this study, we elucidated the mechanism of the protective effects of bimatoprost on RGC against oxidative stress. To examine the protective effects of bimatoprost, cultured RGC with various concentrations of bimatoprost (in both free acid and amide form) were exposed to l-buthionin-(S,R)-sulfoximine (BSO) plus glutamate or serum depletion in vitro and intravitreal injection of N-methyl-D-aspartate (NMDA) was used to induce retinal damage in vivo. To elucidate the protective mechanism of bimatoprost, we used western blot analysis to investigate the phosphorylation of Akt and extracellular signal-regulated kinase (ERK). Bimatoprost significantly reduced BSO plus glutamate- and serum deprivation-induced death in concentration-dependent manners. Bimatoprost induced activation of Akt and ERK, and a phosphatidylinositol 3-kinase inhibitor, LY294002, attenuated the protective effect of bimatoprost. On the other hand, a mitogen-activated protein kinase kinase inhibitor, U0126, exhibited protective effect unexpectedly. Moreover, ERK was more phosphorylated by attenuation of Akt activity in cultured RGC. In an in vivo study, bimatoprost reduced NMDA-induced RGC death. Taken together, these findings indicate that bimatoprost has protective effects on in vitro and in vivo retinal damage, suggesting that the mechanism underlying may be via the Akt pathway, which may modulate the ERK pathway.

The biodisposition and hypertrichotic effects of bimatoprost in mouse skin

Studies on bimatoprost were performed with two objectives: (i) to determine whether bimatoprost possesses hair growth-stimulating properties beyond eyelash hypertrichosis and (ii) to investigate the biodisposition of bimatoprost in skin for the first time. Bimatoprost, at the dose used clinically for eyelash growth (0.03%) and given once daily for 14 days, increased pelage hair growth in C57/black 6 mice. This occurred as a much earlier onset of new hair growth in shaved mice and the time taken to achieve complete hair regrowth, according to photographic documentation and visual assessment. Bimatoprost biodisposition in the skin was determined at three concentrations: 0.01%, 0.03% and 0.06%. Dose-dependent C_max values were obtained (3.41, 6.74, 12.3 μg/g tissue), and cutaneous bimatoprost was well maintained for 24 h following a single dose. Bimatoprost was recovered from the skin only as the intact molecule, with no detectable levels of metabolites. Thus, bimatoprost produces hypertrichosis as the intact molecule.

The prostamide-related glaucoma therapy, bimatoprost, offers a novel approach for treating scalp alopecias

Balding causes widespread psychological distress but is poorly controlled. The commonest treatment, minoxidil, was originally an antihypertensive drug that promoted unwanted hair. We hypothesized that another serendipitous discovery, increased eyelash growth side-effects of prostamide F(2α)-related eyedrops for glaucoma, may be relevant for scalp alopecias. Eyelash hairs and follicles are highly specialized and remain unaffected by androgens that inhibit scalp follicles and stimulate many others. Therefore, we investigated whether non-eyelash follicles could respond to bimatoprost, a prostamide F(2α) analog recently licensed for eyelash hypotrichosis. Bimatoprost, at pharmacologically selective concentrations, increased hair synthesis in scalp follicle organ culture and advanced mouse pelage hair regrowth in vivo compared to vehicle alone. A prostamide receptor antagonist blocked isolated follicle growth, confirming a direct, receptor-mediated mechanism within follicles; RT-PCR analysis identified 3 relevant receptor genes in scalp follicles in vivo. Receptors were located in the key follicle regulator, the dermal papilla, by analyzing individual follicular structures and immunohistochemistry. Thus, bimatoprost stimulates human scalp follicles in culture and rodent pelage follicles in vivo, mirroring eyelash behavior, and scalp follicles contain bimatoprost-sensitive prostamide receptors in vivo. This highlights a new follicular signaling system and confirms that bimatoprost offers a novel, low-risk therapeutic approach for scalp alopecias.

Putative role of prostaglandin receptor in intracerebral hemorrhage

Each year, approximately 795,000 people experience a new or recurrent stroke. Of all strokes, 84% are ischemic, 13% are intracerebral hemorrhage (ICH) strokes, and 3% are subarachnoid hemorrhage strokes. Despite the decreased incidence of ischemic stroke, there has been no change in the incidence of hemorrhagic stroke in the last decade. ICH is a devastating disease 37–38% of patients between the ages of 45 and 64 die within 30 days. In an effort to prevent ischemic and hemorrhagic strokes we and others have been studying the role of prostaglandins and their receptors. Prostaglandins are bioactive lipids derived from the metabolism of arachidonic acid. They sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response. Most prostaglandins are produced from specific enzymes and act upon cells via distinct G-protein coupled receptors. The presence of multiple prostaglandin receptors cross-reactivity and coupling to different signal transduction pathways allow differentiated cells to respond to prostaglandins in a unique manner. Due to the number of prostaglandin receptors, prostaglandin-dependent signaling can function either to promote neuronal survival or injury following acute excitotoxicity, hypoxia, and stress induced by ICH. To better understand the mechanisms of neuronal survival and neurotoxicity mediated by prostaglandin receptors, it is essential to understand downstream signaling. Several groups including ours have discovered unique roles for prostaglandin receptors in rodent models of ischemic stroke, excitotoxicity, and Alzheimer disease, highlighting the emerging role of prostaglandin receptor signaling in hemorrhagic stroke with a focus on cyclic-adenosine monophosphate and calcium (Ca²⁺) signaling. We review current ICH data and discuss future directions notably on prostaglandin receptors, which may lead to the development of unique therapeutic targets against hemorrhagic stroke and brain injuries alike.

An eicosanoid-centric view of atherothrombotic risk factors

Cardiovascular disease is the foremost cause of morbidity and mortality in the Western world. Atherosclerosis followed by thrombosis (atherothrombosis) is the pathological process underlying most myocardial, cerebral, and peripheral vascular events. Atherothrombosis is a complex and heterogeneous inflammatory process that involves interactions between many cell types (including vascular smooth muscle cells, endothelial cells, macrophages, and platelets) and processes (including migration, proliferation, and activation). Despite a wealth of knowledge from many recent studies using knockout mouse and human genetic studies (GWAS and candidate approach) identifying genes and proteins directly involved in these processes, traditional cardiovascular risk factors (hyperlipidemia, hypertension, smoking, diabetes mellitus, sex, and age) remain the most useful predictor of disease. Eicosanoids (20 carbon polyunsaturated fatty acid derivatives of arachidonic acid and other essential fatty acids) are emerging as important regulators of cardiovascular disease processes. Drugs indirectly modulating these signals, including COX-1/COX-2 inhibitors, have proven to play major roles in the atherothrombotic process. However, the complexity of their roles and regulation by opposing eicosanoid signaling, have contributed to the lack of therapies directed at the eicosanoid receptors themselves. This is likely to change, as our understanding of the structure, signaling, and function of the eicosanoid receptors improves. Indeed, a major advance is emerging from the characterization of dysfunctional naturally occurring mutations of the eicosanoid receptors. In light of the proven and continuing importance of risk factors, we have elected to focus on the relationship between eicosanoids and cardiovascular risk factors.

A randomized crossover study comparing tafluprost 0.0015% with travoprost 0.004% in patients with normal-tension glaucoma [corrected]

Purpose:

We compared the intraocular pressure (IOP)-lowering effect of tafluprost 0.0015% once daily with travoprost 0.004% once daily in Japanese patients with normal-tension glaucoma (NTG).

Methods:

One hundred sixteen patients with NTG were randomized to use tafluprost 0.0015% or travoprost 0.004% once daily for 12 weeks, followed by a washout period of 4 weeks between switching medications. IOP was measured at baseline and 4, 8, and 12 weeks of each treatment period.

Results:

Ninety patients completed both treatment periods and had IOP data available for evaluation. In both groups, a significant decrease in IOP was observed for all measurement points compared with baseline values (P < 0.0001). There was no significant difference in IOP at each time point between the two groups. Both drugs were effective (defined as more than 10% IOP reduction) in 39 (43%) of 90 patients; only tafluprost was effective in 26 (29%) patients, and only travoprost was effective in 17 (19%) patients. Eight (9%) patients were nonresponders to both drugs.

Conclusions:

Tafluprost and travoprost were equally effective in lowering IOP in patients with normal-tension glaucoma. However, patients with normal-tension glaucoma may vary in response to each medication.

Iris and periocular adverse reactions to bimatoprost in Japanese patients with glaucoma or ocular hypertension

PURPOSE

To prospectively investigate adverse reactions to bimatoprost in Japanese patients with glaucoma or ocular hypertension. We also examined patient attitudes to adverse reactions via a questionnaire.

METHODS

Fifty-two Japanese patients with glaucoma or ocular hypertension were enrolled. Iridial, eyelid, and eyelash photographs were taken before and at 6 months after bimatoprost treatment. Increase in eyelid pigmentation, iridial pigmentation, eyelash growth and bristle, and vellus hair of the lid was assessed from the photographs. Questionnaires completed by patients provided insight into their subjective judgment of adverse reactions.

RESULTS

Increase in eyelash bristle (53.8%), iris pigmentation (50.0%), eyelash growth (46.2%), vellus hair of the lid (40.4%), and eyelid pigmentation (7.7%) was evident after bimatoprost treatment. The objective and subjective assessments were in agreement in terms of increase in eyelash bristle, eyelash growth, and increase in vellus hair of the lid.

CONCLUSION

Most patients were conscious of these adverse reactions. Before administering bimatoprost, sufficient explanation of potential adverse reactions should be provided; after initiating treatment, careful observation is required.

Prostanoids as regulators of innate and adaptive immunity

Potent, oxygenated lipid molecules called prostanoids regulate a wide variety of physiological responses and pathological processes. Prostanoids are produced by various cell types and act on target cells through specific G protein-coupled receptors. Although prostanoids have historically been considered acute inflammation mediators, studies using specific receptor knockout mice indicate that prostanoids, in fact, regulate various aspects of both innate and adaptive immunity. Each prostanoid, depending on which receptor it acts on, exerts specific effects on immune cells such as macrophages, dendritic cells, and T and B lymphocytes, often in concert with microbial ligands and cytokines, to affect the strength, quality, and duration of immune responses. Prostanoids are also relevant to immunopathology, from inflammation to autoimmunity and cancer. Here, we review the role of prostanoids in regulating immunity, their involvement in immunopathology, and areas of insight that may lead to new therapeutic opportunities.

(R)-Profens are substrate-selective inhibitors of endocannabinoid oxygenation by COX-2

Cyclooxygenase-2 (COX-2) catalyzes the oxygenation of arachidonic acid and the endocannabinoids 2-arachidonoylglycerol and arachidonoylethanolamide. Evaluation of a series of COX-2 inhibitors revealed that many weak competitive inhibitors of arachidonic acid oxygenation are potent inhibitors of endocannabinoid oxygenation. (R) enantiomers of ibuprofen, naproxen and flurbiprofen, which are considered to be inactive as COX-2 inhibitors, are potent 'substrate-selective inhibitors' of endocannabinoid oxygenation. Crystal structures of the COX-2–(R)-naproxen and COX-2–(R)-flurbiprofen complexes verified this unexpected binding and defined the orientation of the (R) enantiomers relative to (S) enantiomers. (R)-Profens selectively inhibited endocannabinoid oxygenation by lipopolysaccharide-stimulated dorsal root ganglion (DRG) cells. Substrate-selective inhibition provides new tools for investigating the role of COX-2 in endocannabinoid oxygenation and a possible explanation for the ability of (R)-profens to maintain endocannabinoid tone in models of neuropathic pain.

Comparison of human ocular distribution of bimatoprost and latanoprost

PURPOSE

This study investigated the ocular distribution of bimatoprost, latanoprost, and their acid hydrolysis products in the aqueous humor, cornea, sclera, iris, and ciliary body of patients treated with a single topical dose of 0.03% bimatoprost or 0.005% latanoprost for understanding concentration-activity relationships.

METHODS

Thirty-one patients undergoing enucleation for an intraocular tumor not affecting the anterior part of the globe were randomized to treatment with bimatoprost or latanoprost at 1, 3, 6 or 12 h prior to surgery. Concentrations of bimatoprost, bimatoprost acid, latanoprost, and latanoprost acid in the human aqueous and ocular tissues were measured using liquid chromatography tandem mass spectrometry.

RESULTS

Following topical administration, intact bimatoprost was distributed in human eyes with a rank order of cornea/sclera >iris/ciliary body >aqueous humor. Bimatoprost acid was also detected in these tissues, where its low levels in the cornea relative to that of latanoprost acid indicated that bimatoprost hydrolysis was limited. Latanoprost behaved as a prodrug that entered eyes predominantly via the corneal route. Levels of latanoprost acid were distributed as cornea >>aqueous humor>iris>sclera>ciliary body.

CONCLUSIONS

Our study provided experimental evidence that levels of bimatoprost in relevant ocular tissues, and not only aqueous humor, are needed to understand the mechanisms by which bimatoprost lowers intraocular pressure (IOP) in human subjects. The data suggest that bimatoprost reached the target tissues favoring the conjunctival/scleral absorption route. Findings of intact bimatoprost in the target ciliary body indicated its direct involvement in reducing IOP. However, bimatoprost acid may have only a limited contribution on the basis that bimatoprost has greater/similar IOP-lowering efficacy than latanoprost, yet bimatoprost acid levels were a fraction of latanoprost acid levels in the aqueous humor and cornea and only sporadically detectable in the ciliary body. In this report, human ocular tissues were examined concurrently with aqueous humor for the in vivo distribution of bimatoprost, bimatoprost acid, latanoprost, and latanoprost acid.

Balancing efficacy and tolerability of prostaglandin analogues and prostaglandin-timolol fixed combinations in primary open-angle glaucoma

BACKGROUND

Lowering intraocular pressure (IOP) is currently the only therapeutic approach that preserves visual function in primary open-angle glaucoma. In making treatment decisions for first- and second-line therapy, the clinician needs to provide an appropriate balance of efficacy and tolerability. Prostaglandin analogues (PGAs) are frequently used as first-line monotherapy, because of their efficacy and low risk of systemic side effects. Similarly, PGA-based fixed combinations are frequently used in patients who progress or fail to achieve the target IOP.

SCOPE

We have reviewed the literature on the management of primary open-angle glaucoma with PGAs, both as monotherapies and in fixed combinations.

FINDINGS

In the clinical trial and meta-analysis data identified, bimatoprost 0.03% seems to be associated with a greater overall ability to lower IOP compared with latanoprost, travoprost or tafluprost, at the cost of a slightly higher incidence of conjunctival hyperaemia. Studies indicate that patients' adherence to treatment is generally better with PGAs than with many other monotherapies. In patients requiring more than one IOP-lowering agent, fixed combination treatments may provide improved adherence and tolerability benefits compared with concomitant use of individual treatments. Bimatoprost/timolol fixed combination appears to be slightly more efficacious than latanoprost/timolol or travoprost/timolol, and tolerability differences between the fixed combinations appear to be slight, probably because the addition of timolol to the PGA component lessens the associated hyperaemia. Surveys on EU physician attitudes appear largely in line with these clinical data.

CONCLUSION

An appropriate balance between efficacy and tolerability ensures optimum IOP lowering and reduces the risk of non-adherence. PGAs largely fulfil this need as monotherapies and as components of combinations.