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Background Dry eye is a condition related to long-term topical eye therapy. We wish to evaluate the effectiveness and tolerability of preservative free prostaglandin drops versus benzalkonium chloride containing prostaglandin drops in the treatment of glaucoma. Methods Patients undergoing prostaglandin monotherapy underwent a washout period of at least 1 month after which baseline measurements of dry eye severity were taken. Patients were randomised to receive either 0.0015% tafluprost drops or 0.005% latanoprost preserved with 0.02% benzalkonium chloride. Repeat measurements were taken after a 2-month interval. Results Thirty-five patients completed randomised treatment. No significant difference between groups was found in objective and subjective measurements of dry eye severity. No significant difference was found in measurement of treatment effectiveness. Conclusion Preservative-free and benzalkonium chloride–containing drops were found to be equally effective in lowering IOP with no significant difference in either subjective or objective measurements of dry eye severity.

Lymphangiogenesis plays an important role in homeostasis, metabolism, and immunity, and also occurs during wound-healing. Here, we examined the roles of prostaglandin E2 (PGE2) receptor (EP) signaling in enhancement of lymphangiogenesis in wound healing processes. The hole-punch was made in the ears of male C57BL/6 mice using a metal ear punch. Healing process and lymphangiogenesis together with macrophage recruitment were analyzed in EP knockout mice. Lymphangiogenesis was up-regulated in the granulation tissues at the margins of punched-hole wounds in mouse ears, and this increase was accompanied by increased expression levels of COX-2 and microsomal prostaglandin E synthase-1. Administration of celecoxib, a COX-2 inhibitor, suppressed lymphangiogenesis in the granulation tissues and reduced the induction of the pro-lymphangiogenic factors, vascular endothelial growth factor (VEGF) -C and VEGF-D. Topical applications of selective EP receptor agonists enhanced the expressions of lymphatic vessel endothelial hyaluronan receptor-1 and VEGF receptor-3. The wound-healing processes and recruitment of CD11b-positive macrophages, which produced VEGF-C and VEGF-D, were suppressed under COX-2 inhibition. Mice lacking either EP3 or EP4 exhibited reduced wound-healing, lymphangiogenesis and recruitment of M2 macrophages, compared with wild type mice. Proliferation of cultured human lymphatic endothelial cells was not detected under PGE2 stimulation. Lymphangiogenesis and recruitment of M2 macrophages that produced VEGF-C/D were suppressed in mice treated with a COX-2 inhibitor or lacking either EP3 or EP4 during wound healing. COX-2 and EP3/EP4 signaling may be novel targets to control lymphangiogenesis in vivo.

Aim To compare 24 h intraocular pressure (IOP) control obtained with preservative free (PF) tafluprost 0.0015% versus branded preservative containing latanoprost 0.005% administered as first choice monotherapy in patients with primary open angle glaucoma (POAG) or ocular hypertension (OHT). Methods This prospective, observer-masked, crossover study included consecutive newly diagnosed patients with POAG or OHT, and baseline IOP between 24 and 33 mm Hg. Qualifying patients underwent baseline untreated 24 h IOP monitoring in habitual positions, with Goldmann tonometry at times 10:00, 14:00, 18:00 and 22:00, and Perkins supine tonometry at times 02:00 and 06:00. They were then randomised to either latanoprost or tafluprost, administered in the evening, for 3 months and then switched to the opposite therapy for another 3 months. 24 h monitoring was repeated at the end of each treatment period. Results 38 patients completed the study. Mean untreated 24 h IOP (24.9 mm Hg) was significantly reduced with both prostaglandins (p<0.001). Tafluprost demonstrated similar mean 24 h efficacy compared with latanoprost (17.8 vs 17.7 mm Hg; p=0.417). Latanoprost demonstrated significantly better 24 h trough IOP (15.9 vs 16.3 mm Hg; p=0.041) whereas tafluprost provided significantly lower 24 h IOP fluctuation (3.2 vs 3.8 mm Hg; p=0.008). No significant difference existed between the two prostaglandins for any adverse event. Conclusions PF tafluprost achieved similar 24 h IOP reduction to branded latanoprost. The current study highlights the importance of complete assessment of efficacy over 24 h. Clinical trials registration NCT01162603.

The prostaglandin D2 receptor 1 (DP1), a member of the prostanoid G protein-coupled receptor (GPCR) family, plays critical roles in allergic responses, sleep regulation, immune modulation, and vasodilation. Here, we present five high-resolution cryo-electron microscopy (cryo-EM) structures of the human DP1 receptor, including an apo structure, two inactive state structures bound to two different inverse agonists developed by ONO Pharmaceutical, and two active state structures in complex with the G s protein and bound to the endogenous agonist PGD2 and its selective derivative BW245C. Structural analysis, complemented by molecular dynamics simulations and site-directed mutagenesis, reveals key residues involved in ligand recognition and suggests a distinct activation mechanism for DP1, which lacks most of the conserved class A GPCR motifs. Notably, the unique residue K76 within the conserved sodium pocket acts as a major activation switch, while amphiphilic helix 8 adopts an unconventional orientation essential for receptor function. These findings offer valuable insights into the structure and function of prostanoid receptors and may facilitate the development of therapeutics targeting DP1. The prostaglandin DP1 receptor plays critical roles in allergic responses, sleep regulation, immune modulation, and vasodilation. Here, authors present atomic structures of DP1 in different states revealing molecular mechanisms of receptor inhibition and activation.

Prostanoids are a series of bioactive lipid metabolites that function in an autacoid manner via activation of cognate G-protein-coupled receptors (GPCRs). Here, we report the crystal structure of human prostaglandin (PG) E receptor subtype EP3 bound to endogenous ligand PGE 2 at 2.90 Å resolution. The structure reveals important insights into the activation mechanism of prostanoid receptors and provides a molecular basis for the binding modes of endogenous ligands. Structural analysis of prostaglandin E receptor EP3, a member of the prostanoid receptor subfamily of GPCRs, in complex with the endogenous agonist PGE 2 reveals important interactions and motions required for receptor activation.

Prostaglandins are thought to be important mediators in the initiation of human labour, however the evidence supporting this is not entirely clear. Determining how, and which, prostaglandins change during pregnancy and labour may provide insight into mechanisms governing labour initiation and the potential to predict timing of labour onset. The current study systematically searched the existing scientific literature to determine how biofluid levels of prostaglandins change throughout pregnancy before and during labour, and whether prostaglandins and/or their metabolites may be useful for prediction of labour. The databases EMBASE and MEDLINE were searched for English-language articles on prostaglandins measured in plasma, serum, amniotic fluid, or urine during pregnancy and/or spontaneous labour. Studies were assessed for quality and risk of bias and a qualitative summary of included studies was generated. Our review identified 83 studies published between 1968–2021 that met the inclusion criteria. As measured in amniotic fluid, levels of PGE 2 , along with PGF 2α and its metabolite 13,14-dihydro-15-keto-PGF 2α were reported higher in labour compared to non-labour. In blood, only 13,14-dihydro-15-keto-PGF 2α was reported higher in labour. Additionally, PGF 2α , PGF 1α , and PGE 2 were reported to increase in amniotic fluid as pregnancy progressed, though this pattern was not consistent in plasma. Overall, the evidence supporting changes in prostaglandin levels in these biofluids remains unclear. An important limitation is the lack of data on the complexity of the prostaglandin pathway outside of the PGE and PGF families. Future studies using new methodologies capable of co-assessing multiple prostaglandins and metabolites, in large, well-defined populations, will help provide more insight as to the identification of exactly which prostaglandins and/or metabolites consistently change with labour. Revisiting and revising our understanding of the prostaglandins may provide better targets for clinical monitoring of pregnancies. This study was supported by the Canadian Institutes of Health Research.

The prostanoid pathway converts polyunsaturated fatty acids (PUFAs) into bioactive lipid mediators, including prostaglandins, thromboxanes and prostacyclins, all of which play vital roles in the immune and reproductive systems in most animal phyla. In crustaceans, PUFAs and prostaglandins have been detected and often associated with female reproductive maturation. However, the presence of prostanoid biosynthesis genes remained in question in these species. In this study, we outlined the prostanoid pathway in the black tiger shrimp Penaeus monodon based on the amplification of nine prostanoid biosynthesis genes: cytosolic phospholipase A2, hematopoietic prostaglandin D synthase, glutathione-dependent prostaglandin D synthase, prostaglandin E synthase 1, prostaglandin E synthase 2, prostaglandin E synthase 3, prostaglandin F synthase, thromboxane A synthase and cyclooxygenase. TBLASTX analysis confirmed the identities of these genes with 51-99% sequence identities to their closest homologs. In addition, prostaglandin F2α (PGF2α), which is a product of the prostaglandin F synthase enzyme, was detected for the first time in P. monodon ovaries along with the previously identified PUFAs and prostaglandin E2 (PGE2) using RP-HPLC and mass-spectrometry. The prostaglandin synthase activity was also observed in shrimp ovary homogenates using in vitro activity assay. When prostaglandin biosynthesis was examined in different stages of shrimp ovaries, we found that the amounts of prostaglandin F synthase gene transcripts and PGF2α decreased as the ovaries matured. These findings not only indicate the presence of a functional prostanoid pathway in penaeid shrimp, but also suggest a possible role of the PGF2α biosynthesis in shrimp ovarian development.

Prostanoids signal through G-protein-coupled receptors to regulate diverse physiological processes. Structures of three prostanoid receptors in inactive and active conformations now uncover the molecular determinants of ligand recognition and receptor activation and offer new opportunities for drug discovery.