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Photopic light-mediated down-regulation of local α_1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis.

ABSTRACT: We have reported the gateway reflex, which describes specific neural activations that regulate immune cell gateways at specific blood vessels in the central nervous system (CNS). Four types of gateway reflexes exist, all of which induce alterations in endothelial cells at specific vessels of the blood-brain barrier followed by inflammation in the CNS in the presence of CNS-autoreactive T cells. Here we report a new gateway reflex that suppresses the development of retinal inflammation by using an autoreactive T cell-mediated ocular inflammation model. Exposure to photopic light down-regulated the adrenoceptor pathway to attenuate ocular inflammation by suppressing breaching of the blood-retina barrier. Mechanistic analysis showed that exposure to photopic light down-regulates the expression of α_1A-adrenoceptor (α_1AAR) due to high levels of norepinephrine and epinephrine, subsequently suppressing inflammation. Surgical ablation of the superior cervical ganglion (SCG) did not negate the protective effect of photopic light, suggesting the involvement of retinal noradrenergic neurons rather than sympathetic neurons from the SCG. Blockade of α_1AAR signaling under mesopic light recapitulated the protective effect of photopic light. Thus, targeting regional adrenoceptor signaling might represent a novel therapeutic strategy for autoimmune diseases including those that affect organs separated by barriers such as the CNS and eyes.

SUBMITTER: Stofkova A

PROVIDER: S-EPMC6382936 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe oral immunomodulatory agent laquinimod is currently evaluated for multiple sclerosis (MS) treatment. Phase II and III studies demonstrated a reduction of degenerative processes. In addition to anti-inflammatory effects, laquinimod might have neuroprotective properties, but its impact on the visual system, which is often affected by MS, is unknown. The aim of our study was to investigate potential protective effects of laquinimod on the optic nerve and retina in an experimental autoimmune encephalomyelitis (EAE) model.MethodsWe induced EAE in C57/BL6 mice via MOG35-55 immunization. Animals were divided into an untreated EAE group, three EAE groups receiving laquinimod (1, 5, or 25 mg/kg daily), starting the day post-immunization, and a non-immunized control group. Thirty days post-immunization, scotopic electroretinograms were carried out, and mice were sacrificed for histopathology (HE, LFB), immunohistochemistry (MBP, Iba1, Tmem119, F4/80, GFAP, vimentin, Brn-3a, cleaved caspase 3) of the optic nerve and retina, and retinal qRT-PCR analyses (Brn-3a, Iba1, Tmem119, AMWAP, CD68, GFAP). To evaluate the effect of a therapeutic approach, EAE animals were treated with 25 mg/kg laquinimod from day 16 when 60% of the animals had developed clinical signs of EAE.ResultsLaquinimod reduced neurological EAE symptoms and improved the neuronal electrical output of the inner nuclear layer compared to untreated EAE mice. Furthermore, cellular infiltration, especially recruited phagocytes, and demyelination in the optic nerve were reduced. Microglia were diminished in optic nerve and retina. Retinal macroglial signal was reduced under treatment, whereas in the optic nerve macroglia were not affected. Additionally, laquinimod preserved retinal ganglion cells and reduced apoptosis. A later treatment with laquinimod in a therapeutic approach led to a reduction of clinical signs and to an improved b-wave amplitude. However, no changes in cellular infiltration and demyelination of the optic nerves were observed. Also, the number of retinal ganglion cells remained unaltered.ConclusionFrom our study, we deduce neuroprotective and anti-inflammatory effects of laquinimod on the optic nerve and retina in EAE mice, when animals were treated before any clinical signs were noted. Given the fact that the visual system is frequently affected by MS, the agent might be an interesting subject of further neuro-ophthalmic investigations.

Project description:BACKGROUND: Advances in gene transfer techniques have provided long-term, safe and stable transduction of retinal cells following subretinal injection with adeno-associated viral (AAV) vectors. In this study we investigated whether subretinal injection of AAV2-murine IL-27p28 vector was effective in inhibiting experimental autoimmune uveoretinitis (EAU) induced in B10RIII mice. METHODOLOGY/PRINCIPAL FINDINGS: An AAV2 vector encoding the murine IL-27p28 gene (rAAV2-CMV-mIL-27p28) was prepared and subretinally injected into B10RIII mice (4.35×10(8) vector genome (v.g.)). AAV2 vector mediating green fluorescent protein (rAAV2-CMV-GFP) served as a control (5×10(8) v.g.). The concentration of mIL-27p28 in homogenized eyes and serum was assayed by enzyme linked immunosorbent assay (ELISA) after subretinal injection. Human IRBP(161-180) peptide and Complete Freund's Adjuvant were injected into mice receiving either the rAAV2-CMV-mIL-27p28 or rAAV2-CMV-GFP vector. EAU was evaluated clinically and pathologically. The level of IL-17 and IL-10 in homogenized eyes was measured on day 12 and day 21 following immunization. Delayed type hypersensitivity (DTH) and IRBP(161-180)-specific proliferation of lymphocytes from the spleen and lymph nodes were assayed to examine the influence of the subretinal delivery of rAAV2-CMV-mIL-27p28 on the systemic immune response. IL-27p28 was detectable by ELISA within the eyes from two weeks following subretinal injection of the rAAV2-CMV-mIL-27p28 vector and showed a sustained high expression from day 14 to 9 months with a highest expression at 5 months. Subretinal injection of the vector significantly attenuated the severity of EAU disease clinically and pathologically in association with a significantly decreased IL-17 expression and an increased IL-10 expression. The IL-27p28 vector did not affect the systemic immune response, as determined by DTH and IRBP(161-180)-specific lymphocyte proliferation. CONCLUSIONS/SIGNIFICANCE: A high and stable expression of IL-27p28 was observed for at least 9 months following subretinal delivery of rAAV2-CMV-mIL-27p28. The amelioration of EAU disease severity was associated with a decreased IL-17 expression and an increased IL-10 expression.

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Photopic light-mediated down-regulation of local α_1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis.

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Photopic light-mediated down-regulation of local α1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Photopic light-mediated down-regulation of local α_1A-adrenergic signaling protects blood-retina barrier in experimental autoimmune uveoretinitis.