Karine Bigot

CX3CR1+ CD115+ CD135+ common macrophage/DC precursors and the role of CX3CR1 in their response to inflammation.

CX3CR1 expression is associated with the commitment of CSF-1R+ myeloid precursors to the macrophage/dendritic cell (DC) lineage. However, the relationship of the CSF-1R+ CX3CR1+ macrophage/DC precursor (MDP) with other DC precursors and the role of CX3CR1 in macrophage and DC development remain unclear. We show that MDPs give rise to conventional DCs (cDCs), plasmacytoid DCs (PDCs), and monocytes, including Gr1+ inflammatory monocytes that differentiate into TipDCs during infection. CX3CR1 deficiency selectively impairs the recruitment of blood Gr1+ monocytes in the spleen after transfer and during acute Listeria monocytogenes infection but does not affect the development of monocytes, cDCs, and PDCs.

Sirt1 Involvement in rd10 Mouse Retinal Degeneration

PURPOSE Sirtuin1 (Sirt1) is an NAD(+)-dependent deacetylase involved in development, cell survival, stress resistance, energy metabolism, and aging. It is expressed in the mammalian central nervous system (CNS) and is activated during processes associated with neuroprotection. The retinal degeneration 10 (rd10) mouse model of retinitis pigmentosa (RP) was used to investigate the possible role of Sirt1 in this type of retinal degeneration. METHODS Eyes from control and rd10 mice were used. Sirt1 mRNA was detected by in situ hybridization, and its abundance was estimated by semiquantitative RT-PCR. The presence of Sirt1 protein was investigated by immunohistofluorescence and Western blot analysis. The apoptosis of photoreceptor cells was analyzed by terminal dUTP transferase nick-end labeling (TUNEL). Immunolabeling for Sirt1, apoptosis-inducing factor (Aif), and caspase-12 (Casp-12) was performed on retinal tissue sections. RESULTS Sirt1 mRNA and immunoreactivity were observed in normal adult mouse eyes. In the control retina, Sirt1 was immunolocalized mostly to the nucleus. In rd10 mice with retinal degeneration, changes in Sirt1 immunolabeling were observed only in the retinal outer nuclear layer (ONL). The pathologic pattern of Sirt1 immunoreactivity correlated with the start of retinal degeneration in rd10 mice. CONCLUSIONS The results suggest a link between Sirt1 production and retinal degeneration in rd10 mice. The anti-apoptotic, neuroprotective role of Sirt1 in the mouse retina is based on the involvement of Sirt1 in double DNA strand-break repair mechanisms and in maintaining energy homeostasis in photoreceptor cells. The results suggest that the neuroprotective properties of Sirt1 may gradually weaken in rd10 mouse photoreceptor cells.

Morphologic and electroretinographic phenotype of SR-BI knockout mice after a long-term atherogenic diet.

PURPOSE To evaluate functional and ultrastructural changes in the retina of scavenger receptor B1 (SR-BI) knockout (KO) mice consuming a high fat cholate (HFC) diet. METHODS Three-month-old male KO and wild-type (WT) mice were fed an HFC diet for 30 weeks. After diet supplementation, plasma cholesterol levels and electroretinograms were analyzed. Neutral lipids were detected with oil red O, and immunohistochemistry was performed on cryostat ocular tissue sections. The retina, Bruchs membrane (BM), retinal pigment epithelium (RPE), and choriocapillaris (CC) were analyzed by transmission electron microscopy. RESULTS Using the WT for reference, ultrastructural changes were recorded in HFC-fed SR-BI KO mice, including lipid inclusions, a patchy disorganization of the photoreceptor outer segment (POS) and the outer nuclear layer (ONL), and BM thickening with sparse sub-RPE deposits. Within the CC, there was abnormal disorganization of collagen fibers localized in ectopic sites with sparse and large vacuolization associated with infiltration of macrophages in the subretinal space, reflecting local inflammation. These lesions were associated with electroretinographic abnormalities, particularly increasing implicit time in a- and b-wave scotopic responses. Abnormal vascular endothelial growth factor (VEGF) staining was detected in the outer nuclear layer. CONCLUSIONS HFC-fed SR-BI KO mice thus presented sub-RPE lipid-rich deposits and functional and morphologic alterations similar to some features observed in dry AMD. The findings lend further support to the hypothesis that atherosclerosis causes retinal and subretinal damage that increases susceptibility to some forms of AMD.

A novel antiangiogenic and vascular normalization therapy targeted against human CD160 receptor

A monoclonal anti-CD160 antibody inhibits the growth of new vessels in pathological ocular and tumor neoangiogenesis but not in healthy tissues.

Novel Mouse Model of Monocular Amaurosis Fugax

Background and Purpose— Retinal ischemia is a major cause of visual impairment and is associated with a high risk of subsequent ischemic stroke. The retina and its projections are easily accessible for experimental procedures and functional evaluation. We created and characterized a mouse model of global and transient retinal ischemia and provide a comprehensive chronologic profile of some genes that display altered expression during ischemia. Methods— Ischemia and reperfusion were assessed by observing flat-mounted retinas after systemic fluorescein injection. The temporal pattern of gene expression modulation was evaluated by quantitative reverse transcription–polymerase chain reaction from the occurrence of unilateral 30-minute pterygopalatine artery occlusion until 4 weeks after reperfusion. Electroretinograms evaluated functional sequelae 4 weeks after the ischemic episode and were correlated with histologic lesions. Results— This model is the first to reproduce the features of transient monocular amaurosis fugax resulting from ophthalmic artery occlusion. The histologic structure was roughly conserved, but functional lesions affected ganglion cells, inner nuclear layer cells, and photoreceptor cells. We observed an early and strong upregulation of c-fos, c-jun, Cox-2, Hsp70, and Gadd34 gene expression and a late decrease in Hsp70 transcript levels. Conclusions— A murine model of transient retinal ischemia was successfully developed that exhibited the characteristic upregulation of immediate-early genes and persistent functional deficits. The model should prove useful for investigating mechanisms of injury in genetically altered mice and for testing novel neuroprotective drugs.

Non-viral ocular gene therapy, pEYS606, for the treatment of non-infectious uveitis: Preclinical evaluation of the medicinal product

ABSTRACT Non‐infectious uveitis (NIU) is the first cause of blindness that can be cured if optimal anti‐inflammatory therapy can be achieved. Systemic anti‐TNF (Tumor Necrosis Factor) agents have been recently approved for NIU but no local delivery of anti‐TNF is available. For sustained production of secreted therapeutic proteins into the eye, non‐viral gene therapy using plasmid electrotransfer in the ciliary muscle has been proposed. In this paper, we report the development steps of pEYS606, a clinical‐grade plasmid DNA, devoid of antiobiotic selection gene, encoding a fusion protein consisting of the extracellular domain of the soluble p55 TNF‐&agr; receptor linked to the human IgG1 Fc domain (hTNFR‐Is/hIgG1 or Protein 6), with high affinity for human TNF‐&agr;, for non‐viral gene transfer into the ocular ciliary muscle. Electrotransfer of pEYS606 in the ciliary muscle significantly reduced ocular inflammation in two well‐established rat models of uveitis, the endotoxin‐induced uveitis (EIU) and the experimental autoimmune uveitis (EAU). In addition, in EAU, a significant protection of photoreceptors was demonstrated after pEYS606 treatment. The improved pharmacokinetic profile of intraocularly‐secreted protein as compared to direct intravitreous injection of recombinant protein allowed to demonstrate Protein 6 efficacy at very low concentrations. Based on these results, a phase I/II clinical trial is conducted [ClinicalTrials.gov Identifier: NCT03308045].