Optimising drug therapy for non-infectious uveitis

Emerging Roles of cGAS-STING Signaling in Mediating Ocular Inflammation

Cyclic GMP-AMP (cGAMP) synthase (cGAS), a sensor of cytosolic DNA, recognizes cytoplasmic nucleic acids to activate the innate immune responses via generation of the second messenger cGAMP and subsequent activation of the stimulator of interferon genes (STINGs). The cGAS-STING signaling has multiple immunologic and physiological functions in all human vital organs. It mediates protective innate immune defense against DNA-containing pathogen infection, confers intrinsic antitumor immunity via detecting tumor-derived DNA, and gives rise to autoimmune and inflammatory diseases upon aberrant activation by cytosolic leakage of self-genomic and mitochondrial DNA. Disruptions in these functions are associated with the pathophysiology of various immunologic and neurodegenerative diseases. Recent evidence indicates important roles of the cGAS-STING signaling in mediating inflammatory responses in ocular inflammatory and inflammation-associated diseases, such as keratitis, diabetic retinopathy, age-related macular degeneration, and uveitis. In this review, we summarize the recently emerging evidence of cGAS-STING signaling in mediating ocular inflammatory responses and affecting pathogenesis of these complex eye diseases. We attempt to provide insightful perspectives on future directions of investigating cGAS-STING signaling in ocular inflammation. Understanding how cGAS-STING signaling is modulated to mediate ocular inflammatory responses would allow future development of novel therapeutic strategies to treat ocular inflammation and autoimmunity.

Pathogenesis and current therapies for non-infectious uveitis

Non-infectious uveitis (NIU) is a disorder with various etiologies and is characterized by eye inflammation, mainly affecting people of working age. An accurate diagnosis of NIU is crucial for appropriate therapy. The aim of therapy is to improve vision, relieve ocular inflammation, prevent relapse, and avoid treatment side effects. At present, corticosteroids are the mainstay of topical or systemic therapy. However, repeated injections are required for the treatment of chronic NIU. Recently, new drug delivery systems that may ensure intraocular delivery of therapeutic drug levels have been highlighted. Furthermore, with the development of immunosuppressants and biologics, specific therapies can be selected based on the needs of each patient. Immunosuppressants used in the treatment of NIU include calcineurin inhibitors and antimetabolites. However, systemic immunosuppressive therapy itself is associated with adverse effects due to the inhibition of immune function. In patients with refractory NIU or those who cannot tolerate corticosteroids and immunosuppressors, biologics have emerged as alternative treatments. Thus, to improve the prognosis of patients with NIU, NIU should be managed with different drugs according to the response to treatment and possible side effects.

The Challenge of Treating the Severest Forms of Chronic Noninfectious Posterior and Panuveitis

BACKGROUND

Noninfectious posterior and panuveitis may exhibit a chronic relapsing clinical course and are challenging to treat. Most affected patients are continuously treated with systemic immunosuppressive therapy, which is potentially associated with significant adverse side effects.

METHODS

A cohort of 18 patients presenting with severe noninfectious posterior or panuveitis were evaluated with respect to the clinical course of the disease, with particular focus on best-corrected visual acuity (BCVA), treatment duration, remission rates, reported negative side effects, and the necessity for switching medication.

RESULTS

The mean follow-up was 27.8 months. Although BCVA improved significantly, complete or partial remission was observed in only 66.7% of patients. Of the patients, 72.2% underwent a change in medical treatment due to either adverse events or inefficacy of medication.

CONCLUSION

Despite new immunosuppressive therapies, effective treatment of severe noninfectious posterior and panuveitis remains a major challenge. We discuss the urgent need for novel treatment strategies in order to prevent systemic adverse effects, and to improve visual outcome and quality of life.

Perspectives of Therapeutic Drug Monitoring of Biological Agents in Non-Infectious Uveitis Treatment: A Review

Biological drugs, especially those targeting anti-tumour necrosis factor α (TNFα) molecule, have revolutionized the treatment of patients with non-infectious uveitis (NIU), a sight-threatening condition characterized by ocular inflammation that can lead to severe vision threatening and blindness. Adalimumab (ADA) and infliximab (IFX), the most widely used anti-TNFα drugs, have led to greater clinical benefits, but a significant fraction of patients with NIU do not respond to these drugs. The therapeutic outcome is closely related to systemic drug levels, which are influenced by several factors such as immunogenicity, concomitant treatment with immunomodulators, and genetic factors. Therapeutic drug monitoring (TDM) of drug and anti-drug antibody (ADAbs) levels is emerging as a resource to optimise biologic therapy by personalising treatment to bring and maintain drug concentration within the therapeutic range, especially in those patients where a clinical response is less than expected. Furthermore, some studies have described different genetic polymorphisms that may act as predictors of response to treatment with anti-TNFα agents in immune-mediated diseases and could be useful in personalising biologic treatment selection. This review is a compilation of the published evidence in NIU and in other immune-mediated diseases that support the usefulness of TDM and pharmacogenetics as a tool to guide clinicians’ treatment decisions leading to better clinical outcomes. In addition, findings from preclinical and clinical studies, assessing the safety and efficacy of intravitreal administration of anti-TNFα agents in NIU are discussed.

Anti-Inflammatory Effect of Tacrolimus/Hydroxypropyl-β-Cyclodextrin Eye Drops in an Endotoxin-Induced Uveitis Model

Background: Uveitis is an infrequent disease which constitutes a major cause of ocular morbidity. Correct management is essential, being corticosteroids its cornerstone. In case of contraindication to corticosteroids or treatment failure, the use of topical tacrolimus (TAC) could be an alternative which has already demonstrated safety and effectiveness in other ocular pathologies. However, TAC eye drops are not marketed, thus their elaboration must be carried out in Hospital Pharmacy Departments (HPDs). Methods: 32 Sprague-Dawley rats were divided into 4 groups of 8 rats each: (a) untreated healthy rats (Healthy); (b) untreated Endotoxin-Induced Uveitis model-rats (EIU); (c) EIU-rats treated with standard treatment of dexamethasone ophthalmic drops (DXM) and (d) EIU-rats treated with TAC-hydroxypropyl-β-cyclodextrin eye drops previously developed by our group (TAC-HPβCD). The mRNA expression levels of IL-6, IL-8, MIP-1α and TNF-α, quantitative analysis of leucocytes in aqueous humor and histological evaluation were performed. Results: TAC-HPβCD eye drops demonstrated to reduce ocular inflammation, expression of IL-6, TNF-α, MIP-1α and leukocyte infiltration in aqueous humor. Conclusions: TAC-HPβCD eye drops showed beneficial effect in EIU model in rats, positioning as an alternative for uveitis treatment in case of corticosteroids resistance or intolerance.

Hydrogels-based ophthalmic drug delivery systems for treatment of ocular diseases

An increasing number of people worldwide are affected by eye diseases, eventually leading to visual impairment or complete blindness. Conventional treatment involves the use of eye drops. However, these formulations often confer low ocular bioavailability and frequent dosing is required. Therefore, there is an urgent need to develop more effective drug delivery systems to tackle the current limitations. Hydrogels are multifunctional ophthalmic drug delivery systems capable of extending drug residence time and sustaining release of drugs. In this review, common ocular diseases and corresponding therapeutic drugs are briefly introduced. In addition, various types of hydrogels reported for ophthalmic drug delivery, including in-situ gelling hydrogels, contact lenses, low molecular weight supramolecular hydrogels, cyclodextrin/poly (ethylene glycol)-based supramolecular hydrogels and hydrogel-forming microneedles, are summarized. Besides, marketed hydrogel-based opthalmic formulations and clinical trials are also highlighted. Finally, critical considerations regarding clinical translation of biologics-loaded hydrogels are discussed.

Childhood Uveitis

Childhood uveitis is an ophthalmological challenge, since on the one hand it often remains asymptomatic and difficult to detect, and on the other hand it often has a chronic course and is associated with a high risk of complications threatening the vision. The most important risk factors for childhood uveitis are underlying rheumatic diseases; recommendations for ophthalmological monitoring have been developed together with paediatric rheumatologists. Intermediate and posterior uveitis are rare in children. The therapy must effectively control inflammation and at the same time cause only minimal side effects. Since steroids in particular cause side effects frequently, an immunosuppressive therapy must be initiated early in an interdisciplinary cooperation with paediatric rheumatologists and parents with the goal of minimising steroids.

Recent advances in the management of non-infectious posterior uveitis

PURPOSE

To review the current regimens and novel therapeutic modalities in various stages of research and development for the management of non-infectious posterior uveitis (NIPU).

METHODS

We performed a thorough review of current literature using PubMed, Google Scholar and Clinicaltrials.gov to identify the published literature about the available therapeutics and novel drugs/therapies in different stages of clinical trials.

RESULTS

The current management regimen for non-infectious posterior uveitis includes corticosteroids, immunomodulatory therapies and anti-metabolites. However, NIPU requires long-term management for efficacious remission of the disease and to prevent disease relapse. Long-term safety issues associated with steroids have led to efforts to develop novel therapeutic agents including biological response modulators and immunosuppressants. The current therapeutic agents in various stages of development include calcineurin inhibitors, biologic response modifiers and a more a comprehensive modalities like ocular gene therapy as well as novel drug delivery mechanisms for higher bioavailability to the target tissues, with minimal systemic effects.

CONCLUSION

Novel efficacious therapeutic modalities under development will help overcome the challenges associated with the traditional therapeutic agents.

New Pharmacological Strategies for the Treatment of Non-Infectious Uveitis. A Minireview

Non-infectious uveitis (NIU) is a group of disorders characterized by intraocular inflammation at different levels of the eye. NIU is a leading cause of irreversible blindness in working-age population in the developed world. The goal of uveitis treatment is to control inflammation, prevent recurrences, and preserve vision, as well as minimize the adverse effects of medications. Currently, the standard of care for NIU includes the administration of corticosteroids (CS) as first-line agents, but in some cases a more aggressive therapy is required. This includes synthetic immunosuppressants, such as antimetabolites (methotrexate, mycophenolate mofetil, and azathioprine), calcineurinic inhibitors (cyclosporine, tacrolimus), and alkylating agents (cyclophosphamide, chlorambucil). In those patients who become intolerant or refractory to CS and conventional immunosuppressive treatment, biologic agents have arisen as an effective therapy. Among the most evaluated treatments, TNF-α inhibitors, IL blockers, and anti-CD20 therapy have emerged. In this regard, anti-TNF agents (infliximab and adalimumab) have shown the strongest results in terms of favorable outcomes. In this review, we discuss latest evidence concerning to the effectiveness of biologic therapy, and present new therapeutic approaches directed against immune components as potential novel therapies for NIU.

Cytokine Profiling in Aqueous Humor Samples From Patients With Non-Infectious Uveitis Associated With Systemic Inflammatory Diseases

Non-infectious uveitis are intraocular inflammatory conditions caused by dysregulated activation of the immune response without any detectable infectious agents. The aim of this study was to explore potential markers and therapeutic targets for two distinct types of non-infectious uveitis associated with Behçet's disease (BD) and Vogt Koyanagi Harada (VKH) disease. Concentrations of 27 cytokines were investigated in aqueous humor (AH) samples from patients with active uveitis vs. healthy controls (HC) (n = 10 patients with BD-associated uveitis; n = 10 patients with VKH-associated uveitis; n = 10 HC) using the Bio-Plex Pro^TM human cytokine group I panel. Additionally, leukocytes in AH samples were counted with hemocytometers and characterized by flow cytometry. Eleven cytokines were differentially expressed between patients with uveitis and HC with a median concentration greater than 10 pg/ml. IL-6, IP-10, G-CSF, and IFNγ showed higher concentrations in AH samples from both BD and VKH patients while IL-2, IL-8, IL-13, TNFα, eotaxin, IL-1ra showed statistically significant higher concentrations only in AH samples from BD patients. GM-CSF was the sole cytokine with an opposite profile showing decreased levels in AH samples from BD patients. IL-1ra and IL-6 were detected at higher frequencies in AH samples from BD and VKH patients compared with those from HC while IFNγ and TNFα were not detected in HC. The concentrations of IL-6, IL-8, IP-10, G-CSF, IFNγ, TNFα, eotaxin, IL-1ra positively correlated with the concentrations of leukocytes in AH, suggesting that such cytokines can be produced by immune cells and/or attract and/or promote proliferation and survival of immune cells in these types of uveitis. The correlation matrix of cytokine concentrations in AH samples revealed that IFNγ, TNFα, eotaxin, IL-6, G-CSF highly correlated each other. The ratios of cytokine concentrations between AH and plasma intra-individuals showed that IL-2, IL-6, IP-10, GM-CSF were increased intraocularly. In conclusion, AH sampling followed by multiplex analysis of cytokines should be fostered in non-infectious uveitis to identify cytokines dysregulated intraocularly in each individual laying the groundwork for precision medicine.