minocycline and Retinal-Diseases

Topics: Anti-Bacterial Agents; Humans; Hyperpigmentation; Minocycline; Retinal Diseases; Sclera

Topics: Aged; Anti-Bacterial Agents; Fluorescein Angiography; Humans; Male; Minocycline; Retinal Diseases; Retinal Pigment Epithelium; Rosacea; Scleral Diseases; Tomography, Optical Coherence; Visual Acuity

Microglia reactivity is a hallmark of retinal degenerations and overwhelming microglial responses contribute to photoreceptor death. Minocycline, a semi-synthetic tetracycline analog, has potent anti-inflammatory and neuroprotective effects. Here, we investigated how minocycline affects microglia in vitro and studied its immuno-modulatory properties in a mouse model of acute retinal degeneration using bright white light exposure.. LPS-treated BV-2 microglia were stimulated with 50 μg/ml minocycline for 6 or 24 h, respectively. Pro-inflammatory gene transcription was determined by real-time RT-PCR and nitric oxide (NO) secretion was assessed using the Griess reagent. Caspase 3/7 levels were determined in 661W photoreceptors cultured with microglia-conditioned medium in the absence or presence of minocycline supplementation. BALB/cJ mice received daily intraperitoneal injections of 45 mg/kg minocycline, starting 1 day before exposure to 15.000 lux white light for 1 hour. The effect of minocycline treatment on microglial reactivity was analyzed by immunohistochemical stainings of retinal sections and flat-mounts, and messenger RNA (mRNA) expression of microglia markers was determined using real-time RT-PCR and RNA-sequencing. Optical coherence tomography (OCT) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) stainings were used to measure the extent of retinal degeneration and photoreceptor apoptosis.. Stimulation of LPS-activated BV-2 microglia with minocycline significantly diminished the transcription of the pro-inflammatory markers CCL2, IL6, and inducible nitric oxide synthase (iNOS). Minocycline also reduced the production of NO and dampened microglial neurotoxicity on 661W photoreceptors. Furthermore, minocycline had direct protective effects on 661W photoreceptors by decreasing caspase 3/7 activity. In mice challenged with white light, injections of minocycline strongly decreased the number of amoeboid alerted microglia in the outer retina and down-regulated the expression of the microglial activation marker translocator protein (18 kDa) (TSPO), CD68, and activated microglia/macrophage whey acidic protein (AMWAP) already 1 day after light exposure. Furthermore, RNA-seq analyses revealed the potential of minocycline to globally counter-regulate pro-inflammatory gene transcription in the light-damaged retina. The severe thinning of the outer retina and the strong induction of photoreceptor apoptosis induced by light challenge were nearly completely prevented by minocycline treatment as indicated by a preserved retinal structure and a low number of apoptotic cells.. Minocycline potently counter-regulates microgliosis and light-induced retinal damage, indicating a promising concept for the treatment of retinal pathologies.

Topics: Animals; Anti-Inflammatory Agents; Caspases; Inflammation Mediators; Light; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Microglia; Minocycline; Nerve Degeneration; Neuroprotective Agents; Nitric Oxide; Retina; Retinal Degeneration; Retinal Diseases

Reprogramming of toll-like receptor 4 (TLR4) by brief ischemia or lipopolysacharide (LPS) contributes to superintending tolerance against destructive ischemia in brain. However, beneficial roles of TLR4 signaling in ischemic retina are not well known. This study demonstrated that preconditioning with LPS 48 h prior to the retinal ischemia prevents the cellular damage in morphology with hematoxylin and eosin (H&E) staining and functions of retina with electroretinogram (ERG), while post-ischemia treatment deteriorated it. The preventive effects of LPS preconditioning showed the cell type-specificity of retinal cells. There was complete rescue of ganglion cells, partial rescue of bipolar and photoreceptor cells or no rescue of amacrine cells, respectively. LPS treatment caused the proliferation and migration of retinal microglia and its preconditioning prevented the ischemia-induced microglial activation. Preventive actions from cell damages following LPS preconditioning prior to retinal ischemia were abolished in TLR4 knock-out mice, and by pre-treatments with anti-TLR4 antibody or minocycline, a microglia inhibitor, which themselves had no effects on the retinal ischemia-induced damages or microglia activation. Thus, this study revealed that TLR4 mediates the LPS preconditioning-induced preventive effects through microglial activation in the retinal ischemia model.

Topics: Animals; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Electroretinography; Eye Proteins; Gene Expression Regulation; Ischemia; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Minocycline; Retina; Retinal Diseases; Signal Transduction; Time Factors; Toll-Like Receptor 4

The involvement of matrix metalloproteinases (MMPs) in ischemic tissue damage and remodeling has been reported by many investigators. Our study was designed to investigate the involvement of MMPs and of tissue inhibitors of metalloproteinases (TIMPs) in rat retinal ischemic injury, the effect of nitric oxide synthase (NOS) inhibitors on MMPs' activity in this model and whether minocycline (an MMP inhibitor) is protective in retinal ischemia.. Ninety-four rats were used in the study. Ischemia was induced by 90 min elevation of intraocular pressure. MMPs' activities and the effect of NOS inhibitors [aminoguanidine (AG) or N-nitro-L-arginine (NNA)] and minocycline on MMPs' activities were assessed by zymography and TIMPs expression by Western analysis. Morphological damage was quantified by morphometry of hematoxylin and eosin-stained retinal sections.. Retinal extracts exhibited activities of proMMP-9 and proMMP-2. The activity of proMMP-9 increased immediately post ischemia (PI) and peaked to 4.6 times that of normal untreated controls in ischemic retinas and to 2.6 times that of controls in retinas of fellow sham-treated eyes at 24 h PI. The relative amount of TIMP-1 increased to 1.9-fold following ischemia and 2.5-fold in fellow sham-treated eyes at 24 h PI. ProMMP-2 activity increased more than two-fold immediately, at 24 h and at 48 h PI in ischemic retinas, and insignificantly in fellow sham-treated eyes. Treatment with 25 mg/kg AG or NNA caused a non-significant increase in proMMP-9 activity at 24 h PI (3.7- and 2.9-fold, respectively, p>0.6). There was no effect of AG or NNA on the activity of proMMP-2. Minocycline significantly attenuated the retinal ischemic damage, primarily by partially preserving ganglion cells and the inner plexiform layer. Minocyline (0.5 mg/ml or 5 mg/ml) inhibited MMPs' activities in ischemic retinal extracts in vitro.. MMPs participated in morphological ischemic damage to rat retina. Treatment with minocycline dramatically attenuated damage to the retina.

Topics: Animals; Blotting, Western; Disease Models, Animal; Enzyme Inhibitors; Guanidines; Ischemia; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Minocycline; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Sprague-Dawley; Retinal Diseases; Retinal Vessels; Tissue Inhibitor of Metalloproteinase-1

To determine whether minocycline, a compound known to protect the retina against light-induced damage in rodent models, and its structurally related analogues would protect photoreceptor cells in primary bovine retinal cell culture against light and oxidative stress.. Minocycline and its analogues were tested in primary retinal cell culture to see whether they would inhibit light or oxidative stress-induced cell death. Primary cell cultures composed of photoreceptors, bipolar cells, and glial cells were prepared from bovine retinas. The extent of cell death induced by light or oxidative stress was assessed by using Sytox Green (Invitrogen-Molecular Probes, Eugene, OR) a nucleic acid dye uptake assay. Differential protection of photoreceptor cells from stress were examined using immunocytochemistry.. Minocycline and methacycline were cytoprotective against light- or oxidative stress-induced damage of bovine primary photoreceptors in culture with an EC(50) < 10 microM. In contrast, structurally related analogues such as demeclocycline, meclocycline, and doxycycline were phototoxic at >3 to >10 microM. Though demeclocycline was found to be phototoxic, it was cytoprotective (EC(50) = 5 microM) against oxidative stress in the absence of exposure to light.. The protective action of minocycline against light-induced damage in the cell-based assays agrees with earlier reports in animal models and suggests that the in vitro assay using bovine primary retinal cell culture is a suitable model for evaluating compounds for retinal protection. Cellular protection or toxicity produced by structurally related compounds show that minor structural modifications can alter the function of minocycline and lead to potent retinal protective compounds.

Topics: Animals; Anti-Bacterial Agents; Apoptosis; Caspases; Cattle; Cell Culture Techniques; Cytoprotection; Fluorescent Antibody Technique, Indirect; Fluorescent Dyes; Light; Minocycline; Neuroglia; Organic Chemicals; Oxidative Stress; Photoreceptor Cells, Vertebrate; Radiation Injuries, Experimental; Reactive Oxygen Species; Retinal Bipolar Cells; Retinal Diseases; tert-Butylhydroperoxide

The purpose of this study was to determine whether minocycline, a semi-synthetic tetracycline derivative, reduces (a) the in vitro neuronal damage occurring after serum deprivation in cultured retinal ganglion cells (RGC-5, a rat ganglion cell line transformed using E1A virus) and/or (b) the in vivo retinal damage induced by N-methyl-D-aspartate (NMDA) intravitreal injection in mice. In addition, we examined minocycline's putative mechanisms of action against oxidative stress and endoplasmic reticulum (ER) stress. In vitro, retinal damage was induced by 24-h serum deprivation, and cell viability was measured by Hoechst 33342 staining or resazurin reduction assay. In cultures of RGC-5 cells maintained in serum-free medium for up to 24 h, the number of cells undergoing cell death was reduced by minocycline (0.2-20 microM). Serum deprivation resulted in increased oxidative stress, as revealed by an increase in the fluorescence intensity for 5-(and-6)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate (CM-H2DCFDA), a reactive oxygen species (ROS) indicator. Minocycline at 2 and 20 microM inhibited this ROS production. However, even at 20 microM minocycline did not inhibit the retinal damage induced by tunicamycin (an ER stress inducer). Furthermore, in mice in vivo minocycline at 90 mg/kg intraperitoneally administered 60 min before an NMDA intravitreal injection reduced the NMDA-induced retinal damage. These findings indicate that minocycline has neuroprotective effects against in vitro and in vivo retinal damage, and that an inhibitory effect on ROS production may contribute to the underlying mechanisms.

Topics: Animals; Benzimidazoles; Benzoxazoles; Cell Count; Cell Death; Cell Line; Culture Media, Serum-Free; Dose-Response Relationship, Drug; Drug Interactions; Endoplasmic Reticulum; Excitatory Amino Acid Agonists; Fluorescent Dyes; Male; Mice; Minocycline; N-Methylaspartate; Neuroprotective Agents; Propidium; Quinolinium Compounds; Rats; Reactive Oxygen Species; Retina; Retinal Diseases; Retinal Ganglion Cells; Tunicamycin

Topics: Aged; Anti-Bacterial Agents; Conjunctival Diseases; Female; Humans; Minocycline; Pigmentation Disorders; Retinal Diseases; Scleral Diseases