Universität zu Köln

Scholz, Rebecca, Sobotka, Markus, Caramoy, Albert, Stempfl, Thomas, Moehle, Christoph and Langmann, Thomas (2015). Minocycline counter-regulates pro-inflammatory microglia responses in the retina and protects from degeneration. J. Neuroinflamm., 12. LONDON: BMC. ISSN 1742-2094

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Abstract

Background: 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. Methods: LPS-treated BV-2 microglia were stimulated with 50 mu g/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. Results: 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. Conclusions: Minocycline potently counter-regulates microgliosis and light-induced retinal damage, indicating a promising concept for the treatment of retinal pathologies.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Scholz, Rebecca UNSPECIFIED UNSPECIFIED UNSPECIFIED Sobotka, Markus UNSPECIFIED UNSPECIFIED UNSPECIFIED Caramoy, Albert UNSPECIFIED UNSPECIFIED UNSPECIFIED Stempfl, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED Moehle, Christoph UNSPECIFIED UNSPECIFIED UNSPECIFIED Langmann, Thomas UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-386930
DOI:	10.1186/s12974-015-0431-4
Journal or Publication Title:	J. Neuroinflamm.
Volume:	12
Date:	2015
Publisher:	BMC
Place of Publication:	LONDON
ISSN:	1742-2094
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FOCAL CEREBRAL-ISCHEMIA; TRANSGENIC MOUSE MODEL; 18 KDA TSPO; MACULAR DEGENERATION; NITRIC-OXIDE; AUTOIMMUNE ENCEPHALOMYELITIS; PHOTORECEPTOR DEATH; DEPENDENT MECHANISM; AGING RETINA; LIGHT DAMAGE Multiple languages Immunology; Neurosciences Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/38693