Does the Microbiome Cause B27-related Acute Anterior Uveitis?

The Relationship Between Gut Microbiome and Ophthalmologic Diseases: A Comprehensive Review

The gut microbiome has been studied in recent years due to its association with various pathological pathways involved in different diseases, caused by its structure, function, and diversity alteration. The knowledge of this mechanism has generated interest in the investigation of its relationship with ophthalmologic diseases. Recent studies infer the existence of a gut-eye microbiota axis, influenced by the intestinal barrier, the blood-retina barrier, and the immune privilege of the eye. A common denominator among ophthalmologic diseases that have been related to this axis is inflammation, which is perpetuated by dysbiosis, causing an alteration of the intestinal barrier leading to increased permeability and, in turn, the release of components such as lipopolysaccharides (LPS), trimethylamine oxide (TMAO), and bacterial translocation. Some theories explain that depending on how the microbiome is composed, a different type of T cells will be activated, while others say that some bacteria can pre-activate T cells that mimic ocular structures and intestinal permeability that allow leakage of metabolites into the circulation. In addition, therapies such as probiotics, diet, and fecal microbiota transplantation (FMT) have been shown to favor the presence of a balanced population of microorganisms that limit inflammation and, in turn, generate a beneficial effect in these eye pathologies. This review aims to analyze how the intestinal microbiome influences various ocular pathologies based on microbial composition and pathological mechanisms, which may provide a better understanding of the diseases and their therapeutic potential.

Exploring the role of gut microbes in spondyloarthritis: Implications for pathogenesis and therapeutic strategies

The gut microbiota plays a pivotal role in regulating host immunity, and dysregulation of this interaction is implicated in autoimmune and inflammatory diseases, including spondyloarthritis (SpA). This review explores microbial dysbiosis and altered metabolic function observed in various forms of SpA, such as ankylosing spondylitis (AS), psoriatic arthritis (PsA), acute anterior uveitis (AAU), and SpA-associated gut inflammation. Studies on animal models and clinical samples highlight the association between gut microbial dysbiosis, metabolic perturbations and immune dysregulation in SpA pathogenesis. These studies have received impetus through next-generation sequencing methods, which have enabled the characterization of gut microbial composition and function, and host gene expression. Microbial/metabolomic studies have revealed potential biomarkers and therapeutic targets, such as short-chain fatty acids, and tryptophan metabolites, offering insights into disease mechanisms and treatment approaches. Further studies on microbial function and its modulation of the immune response have uncovered molecular mechanisms underlying various SpA. Understanding the complex interplay between microbial community structure and function holds promise for improved diagnosis and management of SpA and other autoimmune disorders.

Mechanisms of blood-retinal barrier disruption related to intraocular inflammation and malignancy

Blood-retinal barrier (BRB) disruption is a common accompaniment of intermediate, posterior and panuveitis causing leakage into the retina and macular oedema resulting in vision loss. It is much less common in anterior uveitis or in patients with intraocular lymphoma who may have marked signs of intraocular inflammation. New drugs used for chemotherapy (cytarabine, immune checkpoint inhibitors, BRAF inhibitors, EGFR inhibitors, bispecific anti-EGFR inhibitors, MET receptor inhibitors and Bruton tyrosine kinase inhibitors) can also cause different types of uveitis and BRB disruption. As malignant disease itself can cause uveitis, particularly from breast, lung and gastrointestinal tract cancers, it can be clinically difficult to sort out the cause of BRB disruption. Immunosuppression due to malignant disease and/or chemotherapy can lead to infection which can also cause BRB disruption and intraocular infection. In this paper we address the pathophysiology of BRB disruption related to intraocular inflammation and malignancy, methods for estimating the extent and effect of the disruption and examine why some types of intraocular inflammation and malignancy cause BRB disruption and others do not. Understanding this may help sort and manage these patients, as well as devise future therapeutic approaches.

Unveiling Differential Responses of Granulocytes to Distinct Immunostimulants with Implications in Autoimmune Uveitis

The perception of circulating granulocytes as cells with a predetermined immune response mainly triggered by pathogens is evolving, recognizing their functional heterogeneity and adaptability, particularly within the neutrophil subset. The involvement of these cells in the pathophysiology of autoimmune uveitis has become increasingly clear, yet their exact role remains elusive. We used an equine model for autoimmune-mediated recurrent pan-uveitis to investigate early responses of granulocytes in different inflammatory environments. For this purpose, we performed differential proteomics on granulocytes from healthy and diseased horses stimulated with IL8, LPS, or PMA. Compared to healthy horses, granulocytes from the recurrent uveitis model significantly changed the cellular abundance of 384 proteins, with a considerable number of specific changes for each stimulant. To gain more insight into the functional impact of these stimulant-specific proteome changes in ERU pathogenesis, we used Ingenuity Pathway Analysis for pathway enrichment. This resulted in specific reaction patterns for each stimulant, with IL8 predominantly promoting Class I MHC-mediated antigen processing and presentation, LPS enhancing processes in phospholipid biosynthesis, and PMA, clearly inducing neutrophil degranulation. These findings shed light on the remarkably differentiated responses of neutrophils, offering valuable insights into their functional heterogeneity in a T-cell-driven disease. Raw data are available via ProteomeXchange with identifier PXD013648.

The Microbiome and Uveitis: A Narrative Review

The human intestinal microbiome is composed of hundreds of species and has recently been recognized as an important source of immune homeostasis. While dysbiosis, an altered microbiome from the normal core microbiome, has been associated with both intestinal and extraintestinal autoimmune disorders, including uveitis, causality has been difficult to establish. There are four proposed mechanisms of how the gut microbiome may influence the development of uveitis: molecular mimicry, imbalance of regulatory and effector T cells, increased intestinal permeability, and loss of intestinal metabolites. This review summarizes current literature on both animal and human studies that establish the link between dysbiosis and the development of uveitis, as well as provides evidence for the above mechanisms. Current studies provide valuable mechanistic insights as well as identify potential therapeutic targets. However, study limitations and the wide variability in the intestinal microbiome among populations and diseases make a specific targeted therapy difficult to establish. Further longitudinal clinical studies are required to identify any potential therapeutic that targets the intestinal microbiome.

Persistent Inflammation Associated With HLA-B27 After Pars Plana Vitrectomy With Scleral Buckle Placement

Purpose: To report 2 cases of persistent inflammation associated with human leukocyte antigen-B27 (HLA-B27) after pars plana vitrectomy (PPV) with scleral buckling. Methods: Two cases were analyzed. Results: A 47-year-old man had pars plana vitrectomy (PPV), scleral buckle (SB) placement, and endolaser for a macula-on rhegmatogenous retinal detachment (RRD). A 61-year-old man also had uneventful PPV, SB placement, and endolaser for a macula-off RRD. Postoperatively, both patients reported eye pain and had persistent intraocular inflammation. Both were found to be HLA-B27 positive despite having no previous signs or symptoms that would warrant HLA-B27 testing. Conclusions: Discovering the source of prolonged postoperative inflammation is critical in initiating the correct treatment and removing suspicion of infection. Although intraocular inflammation associated with HLA-B27 does not often present initially after surgery, HLA-B27 testing should be considered in cases of persistent, unexpected postoperative inflammation.

Microbiome in Immune-Mediated Uveitis

In the last decades, personalized medicine has been increasing its presence in different fields of medicine, including ophthalmology. A new factor that can help us direct medicine towards the challenge of personalized treatments is the microbiome. The gut microbiome plays an important role in controlling immune response, and dysbiosis has been associated with immune-mediated diseases such as non-infectious uveitis (NIU). In this review, we gather the published evidence, both in the pre-clinical and clinical studies, that support the possible role of intestinal dysbiosis in the pathogenesis of NIU, as well as the modulation of the gut microbiota as a new possible therapeutic target. We describe the different mechanisms that have been proposed to involve dysbiosis in the causality of NIU, as well as the potential pharmacological tools that could be used to modify the microbiome (dietary supplementation, antibiotics, fecal microbiota transplantation, immunomodulators, or biologic drugs) and, consequently, in the control of the NIU. Furthermore, there is increasing scientific evidence suggesting that the treatment with anti-TNF not only restores the composition of the gut microbiota but also that the study of the composition of the gut microbiome will help predict the response of each patient to anti-TNF treatment.

Mycobiomes of the Ocular Surface in Bacterial Keratitis Patients

Inflammation of the cornea is known as keratitis, and bacteria, fungi, protozoans, and viruses are the etiological agents of this disease. Delayed treatment of keratitis could result in loss of vision and, under certain severity conditions, the removal of an eye and its associated structures. In the current study, the ocular surface (conjunctiva and cornea) mycobiomes of individuals with bacterial keratitis were compared with the ocular mycobiome (conjunctiva) of healthy individuals, free of any ocular morbidity. Mycobiomes were generated through NGS approach using conjunctival swabs and corneal scrapings as the source of DNA from which ITS2 was amplified and sequenced, as a proxy to identify fungi. The results indicated significant changes in the alpha-diversity indices and in the abundance at the phylum and genera level. Hierarchical clustering using a heatmap showed that the mycobiomes were different. Furthermore, NMDS plots also differentiated the mycobiomes in the three cohorts, implying dysbiosis in the mycobiomes of the conjunctivae and corneal scrapings of bacterial keratitis individuals compared to control individuals. A preponderance of negative interactions in the hub genera in the conjunctival swabs of bacterial keratitis individuals compared to healthy controls further re-emphasized the differences in the mycobiomes. The dysbiotic changes at the genera level in conjunctivae and corneal scrapings of bacterial keratitis individuals are discussed with respect to their possible role in causing or exacerbating ocular surface inflammation. These results demonstrate dysbiosis in the ocular mycobiome in bacterial keratitis patients compared to healthy controls for the first time.

The association between intestinal microbiome and autoimmune uveitis

INTRODUCTION AND OBJECTIVES

The microbiome is strongly implicated in a wide spectrum of immune-mediated diseases, whereas gut commensal microbiota plays a pivotal role in immune and intestinal homeostasis.

MATERIALS AND METHODS

A thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items.

RESULTS

Due to complex interactions with the host genetics and other factors, intestinal dysbiosis has been linked to various immune-mediated disorders. In particular, the role of intestinal microbiota in the pathogenesis of uveitis has been demonstrated by several studies, indicating that changes in the microbiome can trigger autoimmune ocular inflammatory processes or affect their severity.

CONCLUSIONS

This review summarizes how alterations in the intestinal microbiota can conduce to immune-mediated ocular pathologies and how microbiome can be targeted in order to form novel therapeutic approaches to treat these severe and potentially blinding conditions.

Inpatient Ophthalmology Consultations

Comprehensive patient care requires an integrated approach that often includes different specialties. Of these specialties, Ophthalmology stands out with its variable pathologic conditions, unique tools, and special examination techniques, which are not part of the standard training of internal medicine or other specialties. The authors review prior studies focused on inpatient ophthalmology consultations, common reasons for inpatient ophthalmology consultation, and the recommended approach to the most common ocular complaints that could present to the inpatient provider. They also shed light on the basic ocular history and eye examination that should be obtained before requesting an ophthalmic evaluation.

Gut microbiota-microRNA interactions in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic autoimmune inflammatory disability that is part of the rheumatic disease group of spondyloarthropathies. AS commonly influences the joints of the axial skeleton. The contributions to AS pathogenesis of genetic susceptibility (particularly HLA-B27 and ERAP-1) and epigenetic modifications, like non-coding RNAs, as well as environmental factors, have been investigated over the last few years. But the fundamental etiology of AS remains elusive to date. The evidence summarized here indicates that in the immunopathogenesis of AS, microRNAs and the gut microbiome perform critical functions. We discuss significant advances in the immunological mechanisms underlying AS and address potential cross-talk between the gut microbiome and host microRNAs. This critical interaction implicates a co-evolutionary symbiotic link between host immunity and the gut microbiome.

Serpiginous Choroiditis Presenting in Association With Clostridium difficile Infection and Ulcerative Colitis

Purpose:

This work reports a case of serpiginous choroiditis (SC) in association with ulcerative colitis and Clostridium difficile infection.

Methods:

A case report is discussed.

Results:

A 35-year-old man with a history of ulcerative colitis and recently treated C difficile infection presented with a rapid decline in central visual acuity in both eyes. Examination findings included geographic creamy-white lesions extending from the peripapillary region in both eyes. Multimodal imaging and negative infectious workup results supported the diagnosis of SC. Visual acuity and examination findings improved after initiation of systemic prednisone therapy. Adalimumab was initiated as a steroid-sparing treatment. At the last follow-up, 5 months after the initial presentation, SC and ulcerative colitis both remain in remission.

Conclusions:

SC has been previously described in patients with systemic disorders, including autoimmune conditions. This patient developed SC following C difficile infection and in the context of active ulcerative colitis. To our knowledge, this is the first report of SC in association with these entities.

Recent Developments in HLA B27 Anterior Uveitis

There has been steady progress in understanding the pathogenesis, clinical features, and effective treatment of acute anterior uveitis (AU) over the past 5 years. Large gene wide association studies have confirmed that AU is a polygenic disease, with overlaps with the seronegative arthropathies and inflammatory bowel diseases, associations that have been repeatedly confirmed in clinical studies. The role of the microbiome in AU has received increased research attention, with recent evidence indicating that human leukocyte antigen B27 (HLA B27) may influence the composition of the gut microbiome in experimental animals. Extensive clinical investigations have confirmed the typical features of acute AU (AAU) and its response to topical, regional and systemic immunosuppressive treatment. Increased understanding of the role of cytokines has resulted in studies confirming the value of anti-cytokine therapy [anti-tumor necrosis factor (anti-TNF) and interleukin 6 (IL-6) therapy] in severe and recurrent cases of AAU, particularly in subjects with an associated spondyloarthopathy (SpA) and in juvenile idiopathic arthritis (JIA)-associated AAU.

Ocular Microbiota and Intraocular Inflammation

The term ocular microbiota refers to all types of commensal and pathogenic microorganisms present on or in the eye. The ocular surface is continuously exposed to the environment and harbors various commensals. Commensal microbes have been demonstrated to regulate host metabolism, development of immune system, and host defense against pathogen invasion. An unbalanced microbiota could lead to pathogenic microbial overgrowth and cause local or systemic inflammation. The specific antigens that irritate the deleterious immune responses in various inflammatory eye diseases remain obscure, while recent evidence implies a microbial etiology of these illnesses. The purpose of this review is to provide an overview of the literature on ocular microbiota and the role of commensal microbes in several eye diseases. In addition, this review will also discuss the interaction between microbial pathogens and host factors involved in intraocular inflammation, and evaluate therapeutic potential of targeting ocular microbiota to treat intraocular inflammation.

Uveitis and the gut microbiota

Uveitis is a heterogeneous collection of inflammatory diseases of the intraocular uveal tissues and adjacent structures, and they collectively are a significant cause of visual morbidity. In recent years, investigating the contribution of the gut microbiota to autoimmunity, including the development of uveitis, has gained interest. Decreased disease severity has been observed in both the induced experimental autoimmune model of uveitis and the spontaneous RI61H model of uveitis in mice treated with oral broad-spectrum antibiotics and raised in germ-free conditions, implicating a role for the gut microbiota in the development of disease in these models. Also, in support of these findings are the differences in the composition of the microbiota that have been reported in uveitis patients. Proposed mechanisms accounting for the microbiota triggering uveitis include antigenic mimicry and dysbiosis leading to dysregulation of the immune system. An improved understanding of these mechanisms will facilitate potential therapeutic approaches including alteration of the microbiota with probiotic treatment and fecal microbiota transplants.

Implicating Dysbiosis of the Gut Fungal Microbiome in Uveitis, an Inflammatory Disease of the Eye

Purpose

In this study, the gut fungal microbiome of uveitis (UVT) patients was generated and compared with healthy controls (HC) to identify dysbiosis in UVT patients and ascertain the role of gut fungal microbiome in disease pathology.

Methods

In the present study, gut fungal microbiomes were analyzed in the fecal samples of HC (n = 24) and UVT patients (n = 14) using high-throughput Illumina sequencing of ITS2 region of the fungal ribosomal RNA. QIIME and R software were used for data analysis.

Results

The gut fungal richness and diversity were significantly decreased in UVT patients compared to HC. Our analyses showed enrichment of several pathogenic fungi including Malassezia restricta, Candida albicans, Candida glabrata, and Aspergillus gracilis in UVT patients. Heatmap and discriminatory OTUs further confirmed the disparities between UVT and HC microbiomes.

Conclusions

This is the first study demonstrating dysbiosis in the gut fungal communities of UVT patients indicating the importance of fungal microbiome in the disease pathology. These initial findings might warrant further investigation into the fungal microbiome, especially interactions between fungal and bacterial that then might give further insight into how probiotics or fecal transplants might benefit.

Alterations in the Ocular Surface Fungal Microbiome in Fungal Keratitis Patients

Keratitis, an inflammatory disease of the eye, when neglected could lead to sight-threatening complications and ultimately blindness. Globally, over a million people are affected by keratitis annually. Keratitis has a microbial etiology and is caused by bacteria, fungi, viruses, etc. The present study compared the ocular surface fungal microbiome of healthy individuals and individuals with fungal keratitis. Fungal microbiomes from the conjunctival swabs of healthy individuals and from conjunctival swabs and corneal scrapings of individuals with fungal keratitis were generated using ITS2 region amplicons. Microbiomes were sequenced using Illumina MiSeq 2 × 250 base pair chemistry with a paired-end protocol. Based on Alpha diversity indices, phylum and genera level diversity, abundance differences, and heat map analysis, the fungal microbiomes of conjunctival swabs and corneal scrapings of individuals with fungal keratitis exhibited dysbiosis (alterations in the diversity and abundance) compared to the ocular surface microbiome of the healthy control individuals. This is the first report indicating dysbiosis in the fungal microbiome of conjunctival swabs and corneal scrapings in individuals with fungal keratitis. A total of 11 genera present in the majority of the eyes constituted the variable core ocular microbiome.

The microbiome and ophthalmic disease

IMPACT STATEMENT

This review describes a growing body of research on relationships between the microbiome and eye disease. Several groups have investigated the microbiota of the ocular surface; dysregulation of this delicate ecosystem has been associated with a variety of pro-inflammatory states. Other research has explored the effects of the gastrointestinal microbiota on ophthalmic diseases. Characterizing the ways these microbiotas influence ophthalmic homeostasis and pathogenesis may lead to research on new techniques for managing ophthalmic disease.

New developments in uveitis associated with HLA B27

PURPOSE OF REVIEW

Uveitis is the most common, clinically apparent, extra-articular manifestation of axial spondyloarthritis. This review summarizes recent publications related to this form of uveitis.

RECENT FINDINGS

Studies published since the start of 2015 address the worldwide prevalence of human leukocyte antigen (HLA) B27-associated uveitis, the prevalence of axial spondyloarthritis among patients with B27-associated acute anterior uveitis (AAU), the genetics of AAU and some of the clinical implications of AAU. Progress has been made in the treatment of uveitis in general and in the treatment of uveitis in association with spondyloarthropathy in particular. The pathogenesis of AAU might derive clues from the above as well as from an understanding of the microbiome and possibly from knowledge derived from uveitis in association with Ebola.

SUMMARY

Although HLA B27-associated uveitis has been recognized since 1973, a variety of recent observations shed new light on this common clinical association with spondyloarthritis.

A Possible Role of Intestinal Microbiota in the Pathogenesis of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the sacroiliac joints and the spine, for which the pathogenesis is thought to be a result of the combination of host genetic factors and environmental triggers. However, the precise factors that determine one’s susceptibility to AS remain to be unraveled. With 100 trillion bacteria residing in the mammalian gut having established a symbiotic relation with their host influencing many aspects of host metabolism, physiology, and immunity, a growing body of evidence suggests that intestinal microbiota may play an important role in AS. Several mechanisms have been suggested to explain the potential role of the microbiome in the etiology of AS, such as alterations of intestinal permeability, stimulation of immune responses, and molecular mimicry. In this review, the existing evidence for the involvement of the microbiome in AS pathogenesis was discussed and the potential of intestinal microbiome-targeting strategies in the prevention and treatment of AS was evaluated.

Ocular manifestations of inflammatory bowel disease

PURPOSE OF REVIEW

Extraintestinal manifestations (EIMs) of inflammatory bowel disease (IBD) are numerous and can often involve the eye. This review highlights the ocular complications associated with IBD including the critical role the ophthalmologist can play in the diagnosis of IBD, the pathogenesis of IBD, its ocular complications, and the treatment of ocular inflammation associated with IBD.

RECENT FINDINGS

Polygenic and environmental influences, as well as gut microbial dysbiosis, have been implicated in the pathogenesis of IBD. IBD and its EIMs appear to respond well to TNFα-targeted biologics.

SUMMARY

IBD is thought to be caused by polygenic and environmental influences, including a dysbiotic gut microbiota. It is a systemic immune-mediated disease with varying types of ocular manifestations that can precede, occur simultaneously, or follow intestinal involvement. The diagnosis of IBD can be confused with other seronegative spondyloarthropathies as well as Behçet's disease. Treatment of IBD-associated ocular inflammation can range from corticosteroids to steroid-sparing immunosuppression such as azathioprine or methotrexate. Refractory disease can respond well to TNFα inhibitors.