Project description:Injuries to the retinal pigment epithelium (RPE) and outer retina often result in the accumulation of retinal microglia within the subretinal space. These subretinal microglia play crucial roles in inflammation and resolution, but the mechanisms governing their functions are still largely unknown. Our previous research highlighted the protective functions of choroidal gd T cells in response to RPE injury. In the current study, we employed single-cell RNA sequencing approach to delve deeper into the mechanisms involved. We found that gd T cells were the primary producer of interleukin-17 (IL-17) in the choroid. IL-17 signaled through its receptor on the RPE, subsequently triggering the production of interleukin-6 (IL-6). This cascade of cytokines initiated a metabolic reprogramming of subretinal microglia, enhancing their capacity for lipid metabolism. RPE-specific knockout of IL-17 receptor A led to the dysfunction of subretinal microglia and RPE pathology. Collectively, our findings suggest that responding to RPE injury, the choroidal gd T cells can initiate a protective signaling cascade that ensures the proper functioning of subretinal microglia.
Project description:Illumina Infinium HumanMethylation450 BeadChip data from genomic DNA of retinal pigment epithelium from Age-related Macular Degeneration patients or age-matched controls.
Project description:T cells that encounter cultured ocular pigment epithelial cells in vitro are inhibited from undergoing T cell receptor-triggered activation. Because retinal pigment epithelial (RPE) cells are able to suppress T-cell activation, we studied whether RPE cells could suppress cytokine production by activated T helper (Th) cells. In this study we showed that primary cultured RPE cells greatly suppressed activation of bystander CD4+ T cells in vitro, especially the cytokine production by the target T helper cells (Th1 cells, Th2 cells, Th17 cells, but not Th3 cells). Cultured RPE cells and RPE-supernatants significantly suppressed IL-17 producing CD4+ T cells, and RPE cells fully suppressed polarized Th17 cell lines that induced by recombinant proteins, IL-6 and TGFb2. Moreover, RPE cells failed to suppress IL-17 producing T cells in the presence of rIL-6. In addition, Th17 cells exposed to RPE were suppressed via TGFb, which produce RPE cells. These results indicate that retinal PE cells have immunosuppressive capacity in order to inhibit Th17-type effector T cells. Thus, ocular resident cells play a role in establishing immune regulation in the eye. Retinal pigment epithelium suppresses Th17 cells
Project description:Severe, early-onset photoreceptor (PR) degeneration associated with MERTK mutations is thought to result from failed phagocytosis by retinal pigment epithelium (RPE). Notwithstanding, the severity and onset of PR degeneration in mouse models of Mertk ablation is determined by the hypomorphic expression or the loss of the Mertk paralog Tyro3. Here we find that loss of Mertk and reduced expression/loss of Tyro3 led to RPE inflammation, even before eye-opening. Incipient RPE inflammation cascaded to involve microglia activation and PR degeneration with monocyte infiltration. Inhibition of RPE inflammation with the JAK1/2 inhibitor ruxolitinib mitigated PR degeneration in Mertk -/- mice. Neither inflammation nor severe, early-onset PR degeneration were observed in mice with defective phagocytosis alone. Thus, inflammation drives severe, early-onset PR degeneration-associated with Mertk loss of function.
Project description:Age-related macular degeneration (AMD), featured with dysfunction and loss of retinal pigment epithelium (RPE), is lacking efficient therapeutic approaches. According to our previous studies, human amniotic epithelial stem cells (hAESCs) may serve as a potential seed cell source of RPE cells for therapy because they have no ethical concerns, no tumorigenicity, and little immunogenicity. Herein, trichostatin A and nicotinamide can direct hAESCs differentiation into RPE like cells. The differentiated cells display the morphology, marker expression and cellular function of the native RPE cells, and noticeably express little MHC class II antigens and high level of HLA-G. Importantly, visual function and retinal structure of Royal College of Surgeon (RCS) rats, a classical animal model of retinal degeneration, were rescued after subretinal transplantation with the hAESCs-derived RPE like cells. We established a high-efficient, low-cost and safety-guaranteed system for generating functional RPE cells from hAESCs. These results suggest a novel and ideal therapeutic strategy for retinal degeneration diseases
Project description:Progressive dysfunction and death of photoreceptors occurs in blinding diseases such as age-related macular degeneration and retinitis pigmentosa. The MyD88 protein is a central adaptor molecule for innate immune system Toll-like receptors (TLR) and interleukin-1 receptor (IL-1R), which are active in retinal disease and induce cytokine secretion from inflammatory cells. We recently demonstrated that inhibiting MyD88 in mouse models of retinal degeneration led to increased rod photoreceptor survival, which was associated with altered cytokine expression and increased neuroprotective microglia. However, additional molecular changes associated with MyD88 inhibitor-mediated neuroprotection are not known. Quantitative proteomics using iTRAQ LC-MS/MS is a high-throughput method ideal for providing new information about the molecular mechanisms contributing to photoreceptor protection. In this study, we used isobaric tags for relative and absolute quantification (iTRAQ) labeling followed by liquid chromatography–tandem mass spectrometry (LC-MS/MS) for quantitative proteomic analysis on the rd10 mouse model of retinal degeneration to identify protein pathways changed by MyD88 inhibition. A total of 42 proteins were differentially expressed in retinas from mice treated with MyD88 inhibitor compared with control. Notably, increased expression of multiple crystallins and chaperones that respond to cellular stress and have anti-apoptotic properties were identified in the MyD88 inhibited mice. Additional differentially expressed biological processes included pyrophosphatase activity and peptide biosynthesis. These data suggest that inhibiting MyD88 may enhance chaperone-mediated tissue protective pathways. Therefore, this study provides new insight into molecular events that contribute to photoreceptor protection from modulating inflammation.
Project description:T cells that encounter cultured ocular pigment epithelial cells in vitro are inhibited from undergoing T cell receptor-triggered activation. Because retinal pigment epithelial (RPE) cells are able to suppress T-cell activation, we studied whether RPE cells could suppress cytokine production by activated T helper (Th) cells. In this study we showed that primary cultured RPE cells greatly suppressed activation of bystander CD4+ T cells in vitro, especially the cytokine production by the target T helper cells (Th1 cells, Th2 cells, Th17 cells, but not Th3 cells). Cultured RPE cells and RPE-supernatants significantly suppressed IL-17 producing CD4+ T cells, and RPE cells fully suppressed polarized Th17 cell lines that induced by recombinant proteins, IL-6 and TGFb2. Moreover, RPE cells failed to suppress IL-17 producing T cells in the presence of rIL-6. In addition, Th17 cells exposed to RPE were suppressed via TGFb, which produce RPE cells. These results indicate that retinal PE cells have immunosuppressive capacity in order to inhibit Th17-type effector T cells. Thus, ocular resident cells play a role in establishing immune regulation in the eye.
Project description:Pathogen-associated molecular patterns decisively influence antiviral immune responses, whereas the contribution of endogenous signals of tissue damage, also known as “damage-associated molecular patterns” or “alarmins”, remains ill-defined. We show that interleukin-33 (IL-33), an alarmin released from necrotic cells, is necessary for potent CD8+ T cell (CTL) responses to replicating, prototypic RNA and DNA viruses in mice. IL-33 signaled through its receptor on activated CTLs, enhanced clonal expansion in a MyD88-dependent, CTL-intrinsic fashion, determined polyfunctional effector cell differentiation and was necessary for virus control. Moreover, recombinant IL-33 augmented vaccine-induced CTL responses. Radio-resistant cells of the splenic T cell zone produced IL-33, and efficient CTL responses required IL-33 from radio-resistant cells but not from hematopoietic cells. Thus, alarmin release by radio-resistant cells orchestrates protective antiviral CTL responses. 2 groups (wt vs. ST-/- P14 cells), 3 replicates per group.