Chemokine Expression in Murine RPE/Choroid in Response to Systemic Viral Infection and Elevated Levels of Circulating Interferon-γ

Faber, Carsten; Juel, Helene Bæk; Jensen, Benjamin Anderschou Holbech; Christensen, Jan Pravsgaard; Prause, Jan Ulrik; Thomsen, Allan Randrup; Nissen, Mogens Holst

doi:10.1167/iovs.18-25721

Cited by 10 publications

(14 citation statements)

References 55 publications

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“…Our data support the hypothesis that systemic inflammation may contribute to the development of AMD [25,26], as our basal (corresponding to the side of the choroid) pro-inflammatory stimuli induce pro-inflammatory cytokine release in the RPE and a disruption of the RPE barrier function. These results are also supported by a recent in vivo study that showed that a systemic virus infection can alter the expression of chemokines and complement factors in the RPE/choroid [68].…”

Section: Discussionsupporting

confidence: 76%

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

Terheyden

Roider

Klettner

2020

Graefes Arch Clin Exp Ophthalmol

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Purpose Systemic inflammation may be of importance in the development of AMD. RPE cells can recognize danger signals with toll-like receptors (TLR) and may react in a pro-inflammatory manner. In this study, we evaluated the basal and apical secretions of TNFα, IL-6, and IL-1β in primary RPE cells and RPE/choroid explant cells under basolateral stimulation of TLR2, 3, and 4; the effects on barrier function; and their influence on neuronal cell viability. Methods RPE/choroid tissue explants were prepared from porcine eyes and cultivated in modified Ussing chambers; primary porcine RPE cells on transwell plates. Cells were basally stimulated with agonists Pam2CSK4 (Pam; TLR2), polyinosinic/polycytidylic acid (Poly I:C; TLR3), and lipopolysaccharide (LPS; TLR4) for 24 h. Supernatants were evaluated with ELISA for cytokines TNFα, IL-6, and IL-1β. Apical supernatants were applied to SHSY-5Y cells, and cell viability was evaluated in MTT assay. Barrier function was tested by measuring transepithelial electrical resistance (TER) and occludin immunostaining. Results None of the tested TLR agonists was toxic on RPE cells after 24 h of exposure. Unstimulated RPE cells secreted hardly any cytokines. Pam induced IL-6, IL-1ß, and TNFα on the basal and apical sides at all concentrations tested. Poly I:C induced IL-6 and TNFα primarily at the basal side at lower but on both sides at higher concentrations. LPS induced IL-6, IL-1ß, and TNFα apically and basally at all concentrations tested. In the RPE/choroid, a strong difference between apical and basal secretions could be found. IL-6 was constitutively secreted basally, but not apically, but was induced by all agonists on both sides. IL-1ß and TNFα alpha were strongly induced on the basal side by all agonists. TER was reduced by all agonists, with Pam and LPS being effective in all concentrations tested. Occludin expression was unaltered, but the distribution was influenced by the agonists, with a less distinct localization at the cell borders after treatment. None of the agonists or supernatants of treated RPE and RPE/choroid organ cultures exerted any effect on viability of SHSY-5Y cells. Conclusions Danger signals activating TLRs can induce polarized cytokine expression and contribute to the loss of barrier function in the RPE.

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Section: Discussionsupporting

confidence: 76%

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

Terheyden

Roider

Klettner

2020

Graefes Arch Clin Exp Ophthalmol

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“…The cells producing the cytokines remain to be specified. RPE in vivo may produce CCL5 and other cytokines in culture for instance in response to viral infection ( 53 ). Given that we studied dissected retina samples from which the RPE and posterior eyecup was removed, it is however likely that retinal cells not RPE or choroidal cells generate these transcripts.…”

Section: Discussionmentioning

confidence: 99%

Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

2020

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Retinitis Pigmentosa (RP) is a group of inherited retinal diseases characterized by progressive loss of rod followed by cone photoreceptors. An especially early onset form of RP with blindness in teenage years is caused by mutations in mertk, the gene encoding the clearance phagocytosis receptor Mer tyrosine kinase (MerTK). The cause for blindness in mutant MerTK-associated RP (mutMerTK-RP) is the failure of retinal pigment epithelial cells in diurnal phagocytosis of spent photoreceptor outer segment debris. However, the early onset and very fast progression of degeneration in mutMerTK-RP remains unexplained. Here, we explored the role of microglia in the Royal College of Surgeons (RCS) rat model of mutMerTK-RP. We found elevated levels of inflammatory cytokines and CD68 microglia activation marker, and more ionized calcium-binding adapter molecule 1 (Iba-1) positive microglia in RCS retina when compared to wild-type retina as early as postnatal day 14 (P14). Strikingly, renewal of photoreceptor outer segments in P14 wild-type rat retina is still immature with low levels of RPE phagocytosis implying that at this early age lack of this process in RCS rats is unlikely to distress photoreceptors. Although the total number of Iba-1 positive retinal microglia remains constant from P14 to P30, we observed increasing numbers of microglia in the outer retina from P20 implying migration to the outer retina before onset of photoreceptor cell death at ∼P25. Iba-1 and CD68 levels also increase in the retina during this time period suggesting microglia activation. To determine whether microglia affect the degenerative process, we suppressed retinal microglia in vivo using tamoxifen or a combination of tamoxifen and liposomal clodronate. Treatments partly prevented elevation of Iba-1 and CD68 and relocalization of microglia. Moreover, treatments led to partial but significant retention of photoreceptor viability and photoreceptor function. We conclude that loss of the phagocytosis receptor MerTK causes microglia activation and relocalization in the retina before lack of RPE phagocytosis causes overt retinal degeneration, and that microglia activities accelerate loss of photoreceptors in mutMerTK-RP. These results suggest that therapies targeting microglia may delay onset and slow the progression of this blinding disease.

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“…The RPE forms the outer blood-retinal barrier where adhesion and communication between RPE cells is essential to prevent the passage of molecules and ions, and maintain cell polarity. These events allow the correct functioning of the retina and maintain retinal immune privilege [6,7]. Most researchers agree that one of the early events in DR is the dysfunction of RPE, affecting the retina [8].…”

Section: Retinal Pigment Epithelium and Diabetic Retinopathymentioning

confidence: 99%

Elucidating the mechanism of action of alpha-1-antitrypsin using retinal pigment epithelium cells exposed to high glucose. Potential use in diabetic retinopathy

et al. 2020

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Background Alpha-1-antitrypsin is a protein involved in avoidance of different processes that are seen in diabetic retinopathy pathogenesis. These processes include apoptosis, extracellular matrix remodeling and damage of vessel walls and capillaries. Furthermore, because of its antiinflammatory effects, alpha-1-antitrypsin has been proposed as a possible therapeutic approach for diabetic retinopathy. Our group tested alpha-1-antitrypsin in a type 1 diabetes mouse model and observed a reduction of inflammation and retinal neurodegeneration. Thus, shedding light on the mechanism of action of alpha-1-antitrypsin at molecular level may explain how it works in the diabetic retinopathy context and show its potential for use in other retinal diseases. Methods In this work, we evaluated alpha-1-antitrypsin in an ARPE-19 human cell line exposed to high glucose. We explored the expression of different mediators on signaling pathways related to pro-inflammatory cytokines production, glucose metabolism, epithelial-mesenchymal transition and other proteins involved in the normal function of retinal pigment epithelium by RT-qPCR and Western Blot. Results We obtained different expression patterns for evaluated mediators altered with high glucose exposure and corrected with the use of alpha-1-antitrypsin.

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Chemokine Expression in Murine RPE/Choroid in Response to Systemic Viral Infection and Elevated Levels of Circulating Interferon-γ

Cited by 10 publications

References 55 publications

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

Basolateral activation with TLR agonists induces polarized cytokine release and reduces barrier function in RPE in vitro

Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

Elucidating the mechanism of action of alpha-1-antitrypsin using retinal pigment epithelium cells exposed to high glucose. Potential use in diabetic retinopathy

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