phalloidine and Inflammation

Retinal degeneration is a leading cause of visual impairment and blindness worldwide. Microglia reactivity is a hallmark of neurodegenerative diseases and a driving force for retinal cell death and disease progression. Thus, immunomodulation emerges as a potential therapeutic option. AhR deficiency is known to trigger inflammation and previous studies revealed important roles for AhR ligands in neuroprotection without focusing on microglia. Here, we investigate the anti-inflammatory and antioxidant effects of the synthetic aryl hydrocarbon receptor (AhR) ligand 2, 2'-aminophenyl indole (2AI) on microglia reactivity. We showed that 2AI potently reduced pro-inflammatory gene expression and induced antioxidant genes in activated human and murine microglia cells, in LPS-stimulated retinal explants as well as in stressed human ARPE-19 cells. 2AI also diminished LPS-induced nitric oxide (NO) release, their neurotoxic activity on photoreceptor cells, phagocytosis, and migration in murine BV-2 cells as important functional microglia parameters. siRNA-mediated knockdown of AhR partially prevented the previously observed gene regulatory effects in BV-2 cells. Our results show for the first time, that the synthetic AhR agonist 2AI regulates microglia homeostasis, highlighting AhR as a potential drug target for immunomodulatory and antioxidant therapies.

Topics: Animals; Antioxidants; Basic Helix-Loop-Helix Transcription Factors; Cell Line; Cell Movement; Gene Silencing; Homeostasis; Humans; Indoles; Inflammation; Ligands; Lipopolysaccharides; Mice; Microglia; Nitric Oxide; Nitrites; Phagocytosis; Phalloidine; Receptors, Aryl Hydrocarbon; RNA, Small Interfering; Signal Transduction; Wound Healing

Can a specifically acting synthetic spermicide (DSE-37) be combined with a natural microbicide (saponins) for safe, prophylactic contraception?. A 1:1 (w/w) combination of DSE-37 and Sapindus saponins can target sperm and Trichomonas vaginalis precisely without any noticeable off-target effects on somatic cells at effective concentrations.. Broad-spectrum vaginal agents like nonoxynol-9 (N-9) and cellulose sulfate have failed clinically as microbicides due to non-specific off-target effects, whereas agents that specifically target retroviruses have shown promise in clinical trials. DSE-37 and Sapindus saponins, respectively, specifically target human sperm and T. vaginalis in vitro.. A comprehensive study of efficacy and safety was undertaken using in vitro (human cells) and in vivo (rabbit) models. The 1:1 combination of DSE-37 and Sapindus saponins was based on the in vitro spermicidal and anti-Trichomonal activities of the two components. N-9, the spermicide in clinical use, served as reference control. Free sperm thiols were fluorescently glinted to reveal differences in the targets of the test agents.. On/off-target effects were evaluated in vitro against human sperm, T. vaginalis, HeLa, Vk2/E6E7, End1/E6E7 and Lactobacillus jensenii, using standard assays of drug susceptibility, cell viability, flow cytometric assessment of cell apoptosis and qPCR for expression of pro-inflammatory cytokine mRNAs. The spermicidal effect was also recorded live and free thiols on sperm were fluorescently visualized using a commercial kit. In vivo contraceptive efficacy (pregnancy/fertility rates) and safety (vaginal histopathology and in situ immune-labeling of inflammation markers VCAM-1, E-selectin and NFkB) were evaluated in rabbits.. A 0.003% drug 'combination' containing 0.0015% each of DSE-37 and Sapindus saponins in physiological saline irreversibly immobilized 100% human sperm in ∼30 s and eliminated 100% T. vaginalis in 24 h, without causing any detectable toxicity to human cervical (HeLa) cells and Lactobacilli in 24-48 h, in vitro. N-9 at 0.003% exhibited lower microbicidal activity against Trichomonas but failed in spermicidal assays while causing severe toxicity to HeLa cells and Lactobacilli in 12-24 h. The 'combination' of DSE-37 and Sapindus saponins completely prevented pregnancy in rabbits at a vaginal dose of 20 mg (1% in K-Y Jelly), while application of 5% 'combination' in K-Y Jelly for 4 consecutive days caused negligible alterations in epithelial lining of rabbit vagina with only minor changes in levels of inflammation markers. N-9 at a 20 mg vaginal dose prevented pregnancy in 33% animals and a 4-day repeat application of 2% N-9 gel caused severe local toxicity to vaginal epithelium with molecular expression of acute inflammation markers.. The number of animals used for the in vivo efficacy study was limited by the approval of the animal ethics committee.. Anti-Trichomonal contraceptives with specifically acting synthetic component and clinically-proven safe natural component may define a new concept in empowering women to control their fertility and reproductive health.. The study was funded by CSIR-Network Project 'PROGRAM' (BSC0101) and partly by the Ministry of Health and Family Welfare, Government of India (GAP0001). The funding agencies did not play any role in this study and none of the authors had any competing interest(s).

Topics: Aminoquinolines; Animals; Anti-Infective Agents; Contraceptive Agents; Disulfides; Female; HeLa Cells; Humans; Inflammation; L-Lactate Dehydrogenase; Male; Membrane Potential, Mitochondrial; Phalloidine; Rabbits; Sapindus; Semen; Spermatocidal Agents; Spermatozoa; Surface Tension; Surface-Active Agents; Trichomonas vaginalis

Image-based screening, a new and flexible tool in the drug discovery cascade, is amenable to many different targets. This article describes a particular use of the Cellomics ArrayScan in developing a functional screen for histamine H(4) receptor (H(4)R) antagonists that have potential utility in inflammatory diseases of the airways such as asthma, with H(4)R being expressed on a wide variety of immune cells including eosinophils. Exposure to histamine causes eosinophils to migrate from the bloodstream into the tissue where they contribute to inflammation. Migration is manifested through rearrangements of the actin cytoskeleton and phalloidin, a biological peptide, selectively binds F-actin over G-actin and can be used to detect these cytoskeletal changes mediating inflammatory function. A fluorescent conjugate of phalloidin was used to visualize histamine-induced actin polymerization in human eosinophils on the Cellomics ArrayScan. Inhibition of this phenomenon by commercially available histamine receptor antagonists was measured. The selective H(4)R antagonist JNJ7777120 inhibited histamine-induced actin polymerization in eosinophils most potently. This assay illustrates that this phenomenon is mediated through the H(4)R and that the image-based format has enhanced screening utility for identifying selective H(4)R antagonists over traditional flow cytometry methods.

Topics: Actins; Cytoskeleton; Eosinophils; Flow Cytometry; Histamine; Humans; Inflammation; Inhibitory Concentration 50; Models, Biological; Phalloidine; Polymers; Receptors, G-Protein-Coupled; Receptors, Histamine; Receptors, Histamine H4; Sensitivity and Specificity

The regulation of gap junctional communication by histamine was studied in primary cultures of human tonsil high endothelial cells (HUTECs). We evaluated intercellular communication, levels, state of phosphorylation, and cellular distribution of gap junction protein subunits, mainly connexin (Cx)43. Histamine induced a time-dependent reduction in dye coupling (Lucifer yellow) associated with reduction in connexin43 localized at cell-cell appositions (immunofluorescence), without changes in levels and phosphorylation state of connexin43 (immunoblots). These effects were prevented with chlorpheniramine, an H1 receptor blocker; indomethacin, a cyclooxygenase blocker; or GF109203X, a protein kinase C inhibitor. Treatment with phorbol myristate acetate, a protein kinase C activator, and 4bromo (4Br)-A23187, a calcium ionophore, mimicked the histamine-induced effects on dye coupling. 8Bromo-cAMP doubled the dye coupling extent and prevented the histamine-induced reduction in incidence of dye coupling. After 24-h histamine treatment, known to desensitize H1 receptors, reapplication of histamine increased cell coupling in a way prevented by ranitidine, an H2 receptor blocker. Thus, activation of H1 and H2 receptors, which increase intracellular levels of free Ca2+ and cAMP, respectively, may affect gap junctional communication in opposite ways. Stabilization of actin filaments with phalloidine diminished but did not totally prevent histamine-induced cell shape changes and reduction in dye coupling. Hence, the histamine-induced reduction in gap junctional communication between HUTEC is mediated by cytoskeleton-dependent and -independent mechanisms and might contribute to modulate endothelial function in lymphoid tissue.

Topics: Cells, Cultured; Chlorpheniramine; Coloring Agents; Connexin 43; Cyclic AMP; Cyclooxygenase Inhibitors; Cytoskeleton; Dose-Response Relationship, Drug; Endothelial Cells; Enzyme Inhibitors; Gap Junctions; Histamine; Humans; Immunoblotting; Indoles; Indomethacin; Inflammation; Ionophores; Maleimides; Microscopy, Fluorescence; Palatine Tonsil; Phalloidine; Phosphorylation; Protein Kinase C; Tetradecanoylphorbol Acetate; Time Factors