Primate neural retina upregulates IL-6 and IL-10 in response to a herpes simplex vector suggesting the presence of a pro-/anti-inflammatory axis

Abstract

Injection of herpes simplex virus vectors into the vitreous of primate eyes induces an acute, transient uveitis. The purpose of this study was to characterize innate immune responses of macaque neural retina tissue to the herpes simplex virus type 1-based gene delivery vector hrR3. PCR array analysis demonstrated the induction of the pro-inflammatory cytokine IL-6, as well as the anti-inflammatory cytokine IL-10, following hrR3 exposure. Secretion of IL-6 was detected by ELISA and cone photoreceptors and Muller cells were the predominant IL-6 positive cell types. RNA in situ hybridization confirmed that IL-6 was expressed in photoreceptor and Muller cells. The IL-10 positive cells in the inner nuclear layer were identified as amacrine cells by immunofluorescence staining with calretinin antibody. hrR3 challenge resulted in activation of NFκB (p65) in Muller glial cells, but not in cone photoreceptors, suggesting a novel regulatory mechanism for IL-6 expression in cone cells. hrR3 replication was not required for IL-6 induction or NFκB (p65) activation. These data suggest a pro-inflammatory (IL-6)/anti-inflammatory (IL-10) axis exists in neural retina and the severity of acute posterior uveitis may be determined by this interaction. Further studies are needed to identify the trigger for IL-6 and IL-10 induction and the mechanism of IL-6 induction in cone cells.

p38MAPK plays a critical role in induction of a pro-inflammatory phenotype of retinal Müller cells following Zika virus infection

“…As an important supporting glial cell in the retina, Müller cell abnormal function has been linked to many retinal diseases (de Hoz et al, 2016; Sauter and Brandt, 2016; Wang et al, 2015b; Zhong et al, 2012). We found that ZIKV not only replicates productively in Müller cells but also induces a robust inflammatory response.…”

“…Müller cells form an architectural support structure across the whole retina and provide homeostatic and metabolic support to retinal neurons, which are assumedly carried out by astrocytes, oligodendrocytes and ependymal cells in other regions of the CNS (Newman and Reichenbach, 1996; Reichenbach and Bringmann, 2013). Under pathological conditions, Müller cells are activated and produce inflammatory cytokines and growth factors that lead to retinal inflammation, vascular leakage and neuronal degeneration in retinopathies including diabetic retinopathy, age-related macular degeneration and uveitis (de Hoz et al, 2016; Sauter and Brandt, 2016; Wang et al, 2015b; Zhong et al, 2012). Since ZIKV has been detected in cells located in the INL, including those with the morphology of Müller cells (Miner et al, 2016), here, we investigated the effects of ZIKV infection on primary mouse retinal Müller cells.…”

Toll-like receptors 4, 5, 6 and 7 are constitutively expressed in non-human primate retinal neurons

“…Some of the TLRs were present in filamentous cells, suggesting they may be expressed by Muller cells, the predominant glial cell type in the retina. To confirm this, we utilized vimentin antibodies as a Muller cell marker (Bhatia et al, 2009; Sauter and Brandt, 2016) and performed double label IF with antibodies to TLRs 4-7. Staining with the anti-vimentin antibody identified a filamentous pattern of Muller cells extending throughout the retina (Fig 4B).…”

“…Some TLRs were expressed in small, round cells in the INL, suggestive of amacrine cell morphology (Fig 3). We performed double label IF with anti-calretinin antibodies, which label AII amacrine cells (de Souza et al, 2016; Kolb et al, 2002; Mills and Massey, 1999; Sauter and Brandt, 2016), and antibodies to TLRs 4-7 to determine if TLRs were expressed by calretinin positive amacrine cells. The staining pattern of the anti-TLR6 antibody clearly indicated TLR6 positive round cells in the INL (Fig 7A).…”

“…Secretion of IL-6 was detected following herpes simplex virus vector transduction of RPE cells (Cai and Brandt, 2008). Recent studies demonstrated that cytokines, including IL-6 and IL-10, as well as TLRs 6 and 7, were upregulated, following herpes simplex vector challenge of non-human primate neural retina tissue (Sauter and Brandt, 2016). To date, a detailed examination of which TLRs are expressed in NHP neural retina, and the cell types expressing them, has not been done.…”