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NOD-like Receptors in the Eye: Uncovering Its Role in Diabetic Retinopathy.
Lim, RR, Wieser, ME, Ganga, RR, Barathi, VA, Lakshminarayanan, R, Mohan, RR, Hainsworth, DP, Chaurasia, SS
International journal of molecular sciences. 2020;(3)
Abstract
Diabetic retinopathy (DR) is an ocular complication of diabetes mellitus (DM). International Diabetic Federations (IDF) estimates up to 629 million people with DM by the year 2045 worldwide. Nearly 50% of DM patients will show evidence of diabetic-related eye problems. Therapeutic interventions for DR are limited and mostly involve surgical intervention at the late-stages of the disease. The lack of early-stage diagnostic tools and therapies, especially in DR, demands a better understanding of the biological processes involved in the etiology of disease progression. The recent surge in literature associated with NOD-like receptors (NLRs) has gained massive attraction due to their involvement in mediating the innate immune response and perpetuating inflammatory pathways, a central phenomenon found in the pathogenesis of ocular diseases including DR. The NLR family of receptors are expressed in different eye tissues during pathological conditions suggesting their potential roles in dry eye, ocular infection, retinal ischemia, cataract, glaucoma, age-related macular degeneration (AMD), diabetic macular edema (DME) and DR. Our group is interested in studying the critical early components involved in the immune cell infiltration and inflammatory pathways involved in the progression of DR. Recently, we reported that NLRP3 inflammasome might play a pivotal role in the pathogenesis of DR. This comprehensive review summarizes the findings of NLRs expression in the ocular tissues with special emphasis on its presence in the retinal microglia and DR pathogenesis.
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2.
Can vitamin D protect against age-related macular degeneration or slow its progression?
Kaarniranta, K, Pawlowska, E, Szczepanska, J, Jablkowska, A, Błasiak, J
Acta biochimica Polonica. 2019;(2):147-158
Abstract
Dietary vitamin D plays an important role in maintaining proper vision. Age-related macular degeneration (AMD) is a complex eye disease with unknown pathogenesis. Studies on dietary supplementation and AMD occurrence and progression have produced conflicting results. In its advanced stage, AMD may be associated with apoptosis, pyroptosis or necroptosis of retinal cells. Vitamin D has been reported to play a role in modulating each of these programmed death pathways. Vitamin D is a modulator of the immune system and it acts synergistically with two members of the regulators of complement activation family H and I, whose specific variants are the most important genetic factors for AMD pathogenesis. Angiogenesis is an essential component of the neovascular form of AMD, the most devastating type of the disease and vitamin D is reputed to possess antiangiogenic properties. Cellular DNA damage response is weakened in AMD patients and so it is another process that can be modulated by vitamin D. Finally, impaired autophagy is claimed to play a role in AMD and emerging evidence suggests that vitamin D can influence autophagy. Therefore, several pathways of vitamin D metabolism and AMD pathogenesis overlap, suggesting that vitamin D could modulate the course of AMD.
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3.
The role of the intestinal microbiome in ocular inflammatory disease.
Lin, P
Current opinion in ophthalmology. 2018;(3):261-266
Abstract
PURPOSE OF REVIEW The intestinal commensal microbiota are important in shaping immune cell repertoire and are influenced by host genetics. Because of this intricate interaction, an intestinal dysbiosis has been associated with multiple immune-mediated polygenic diseases. This review summarizes the literature on how alterations in the intestinal microbiota contribute to immune-mediated ocular disease, and how to potentially target the gut microbiome for therapeutic benefit. RECENT FINDINGS Several groups have demonstrated the importance of the intestinal microbiome in uveitis pathogenesis. Two groups showed that altering the microbiota with oral antibiotics results in reduced uveitis severity, and another group demonstrated that a commensal bacterial antigen activates retina-specific autoreactive T cells, potentially indicating a commensal trigger for uveitis. We have found that commensal bacterial metabolites, short chain fatty acids, can suppress autoimmune uveitis. Age-related macular degeneration is associated with an intestinal dysbiosis, which can be influenced by genetic risk alleles and age-related eye disease study (AREDS) supplementation. Strategies that might be effective for targeting the intestinal microbiota might involve several approaches, including the use of antibiotics, drugs that supplement beneficial bacterial components or target inflammatory bacterial strains, dietary strategies or microbial transplantation. SUMMARY The intestinal microbiota are potentially crucial in propagating inflammatory diseases of the eye, and can be targeted for therapeutic benefit.
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4.
Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration.
Kersten, E, Paun, CC, Schellevis, RL, Hoyng, CB, Delcourt, C, Lengyel, I, Peto, T, Ueffing, M, Klaver, CCW, Dammeier, S, et al
Survey of ophthalmology. 2018;(1):9-39
Abstract
Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.
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5.
Ocular Immunity and Inflammation.
Albini, TA, Davis, JL
Developments in ophthalmology. 2016;:38-45
Abstract
Complex immunologic mechanisms are involved in multiple intraocular diseases. The field of immunology has aided greatly in better understanding and treating inflammation in the posterior segment. While traditional therapy has relied on drugs such as corticosteroids and antimetabolites that exert there effects by multiple mechanisms, the more recently developed biologic immune modulators involve specific mechanisms of action with the potential to significantly reduce side effects relative to more traditional agents. Better understanding of diseases such as age-related macular degeneration or diabetic retinopathy has led to the appreciation of immune mechanisms involved in these diseases and has suggested potential targets for therapy.
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6.
An overview of the involvement of interleukin-18 in degenerative retinopathies.
Campbell, M, Doyle, SL, Ozaki, E, Kenna, PF, Kiang, AS, Humphries, MM, Humphries, P
Advances in experimental medicine and biology. 2014;:409-15
Abstract
Age-related macular degeneration (AMD) is the leading cause of central vision loss worldwide and while polymorphisms in genes associated with the immune system have been identified as risk factors for disease development, the underlying pathways and mechanisms involved in disease progression have remained unclear. In AMD, localised inflammatory responses related to particulate matter accumulation and subsequent "sterile" inflammation has recently gained considerable interest amongst basic researchers and clinicians alike. Typically, inflammatory responses in the human body are caused as a result of bacterial or viral infection, however in chronic conditions such as AMD, extracellular particulate matter such as drusen can be "sensed" by the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome, culminating in the release of the two pro-inflammatory cytokines IL-1β and IL-18 in the delicate local tissue of the retina. Identification at the molecular level of mediators of the inflammatory response in AMD may yield novel therapeutic approaches to this common and often severe form of blindness. Here, we will describe the role of IL-18 in AMD and other forms of retinal disorders. We will outline some of the key functions of IL-18 as it pertains to maintaining tissue homeostasis in a healthy and degenerating/diseased retina.
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7.
Complement involvement in neovascular ocular diseases.
Yanai, R, Thanos, A, Connor, KM
Advances in experimental medicine and biology. 2012;:161-83
Abstract
Pathological neovascularization (NV) is a hallmark of late stage neovascular age-related macular degeneration (AMD), diabetic retinopathy (DR), and retinopathy of prematurity (ROP). There is accumulating evidence that alterations in inflammatory and immune system pathways that arise from genetic differences, injury, and disease can predispose individuals to retinal neovascular eye diseases. Yet the mechanism of disease progression with respect to the complement system in these maladies is not fully understood. Recent studies have implicated the complement system as an emerging player in the etiology of several retinal diseases. We will summarize herein several of the complement system pathways known to be involved in ocular neovascular pathologies. Current treatment for many neovascular eye diseases focuses on suppression of NV with laser ablation, photodynamic therapy, or anti-VEGF angiogenic inhibitors. However, these treatments do not address the underlying cause of many of these diseases. A clear understanding of the cellular and molecular mechanisms could bring a major shift in our approach to disease treatment and prevention.
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8.
Zinc: role in immunity, oxidative stress and chronic inflammation.
Prasad, AS
Current opinion in clinical nutrition and metabolic care. 2009;(6):646-52
Abstract
PURPOSE OF REVIEW Zinc is essential for multiple cellular functions including immunity. Many investigators have used zinc supplementation in an attempt to affect the outcome of various diseases. These efforts were aimed at either supporting immunity by zinc administration or correcting the zinc dependent immune functions in zinc deficient individuals. RECENT FINDINGS In this review, recent findings of zinc supplementation in various diseases have been presented. Beneficial therapeutic response of zinc supplementation has been observed in the diarrhea of children, chronic hepatitis C, shigellosis, leprosy, tuberculosis, pneumonia, acute lower respiratory tract infection, common cold, and leishmaniasis. Zinc supplementation was effective in decreasing incidences of infections in the elderly, in patients with sickle cell disease (SCD) and decreasing incidences of respiratory tract infections in children. Zinc supplementation has prevented blindness in 25% of the elderly individuals with dry type of AMD. Zinc supplementation was effective in decreasing oxidative stress and generation of inflammatory cytokines such as TNF-alpha and IL-1beta in elderly individuals and patients with SCD. SUMMARY Zinc supplementation has been successfully used as a therapeutic and preventive agent for many conditions. Zinc functions as an intracellular signal molecule for immune cells.