A proteomic approach towards understanding the pathogenesis of Mooren's ulcer

Strategies for successful management of moderate and severe Mooren's ulcer at a rural center during the COVID-19 pandemic: Lessons learnt

PURPOSE

This study aimed to report the strategies that evolved in managing Mooren's ulcer (MU) at a resource-limited center in rural India during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This study includes a retrospective analysis of clinically diagnosed MU cases from January 2021 to August 2021 wherein strategies for management were developed. The demographic profile, ulcer clinical features, treatment algorithms (medical and surgical), complications encountered, referral to a higher center, and compliance with medication and follow-up were studied.

RESULTS

The mean age of presentation was 68.1 years (range, 62-73 years), and 90% were men. The median best-corrected visual acuity (BCVA) was 1.26 logarithm of the Minimum Angle of Resolution (LogMAR) (interquartile range (IQR), 0.00-5 logMAR) in the affected eye on presentation, which improved to 0.69 logMAR (IQR, 0.00-3 logMAR) at resolution ( P = 0.442). The first-line management was conjunctival resection and tissue adhesive application (90%). 70% of cases were unilateral, 50% of cases had less than 2 clock hours of involvement, and 50% had less than 50% stromal involvement. Confounding factors included infectious keratitis (2) and corneal perforation (3). The mean duration of follow-up was 96 (1-240) days. The average follow-up visits per patient were 8.8 (1-22). 90% of cases could be managed successfully at the secondary center level with two cases needing a tertiary care referral.

CONCLUSION

MU can be managed effectively by following a systemic strategy of early diagnosis, surgical therapy, and rapid institution of systemic immunosuppression in a remote location-based secondary center. The strategies developed can be a guide for ophthalmologists at remote centers managing patients or who are unable to travel to tertiary institutes.

Unveiling the Web: Exploring the Multifaceted Role of Neutrophil Extracellular Traps in Ocular Health and Disease

Neutrophil extracellular traps (NETs) play an essential role in antimicrobial defense. However, NETs have also been shown to promote and mediate a wide spectrum of diseases, including cancer, diabetes mellitus, cardiovascular diseases, and ocular diseases. Data regarding NETs in ocular diseases remain limited. In physiological conditions, NETs protect the eye from debris and cleave proinflammatory cytokines, including several interleukins. On the other hand, NETs play a role in corneal diseases, such as dry eye disease and ocular graft-versus-host disease, where they promote acinar atrophy and delayed wound healing. Additionally, NET levels positively correlate with increased severity of uveitis. NETs have also been described in the context of diabetic retinopathy. Although increased NET biomarkers are associated with an increased risk of the disease, NETs also assist in the elimination of pathological blood vessels and the regeneration of normal vessels. Targeting NET pathways for the treatment of ocular diseases has shown promising outcomes; however, more studies are still needed in this regard. In this article, we summarize the literature on the protective roles of NETs in the eye. Then, we describe their pathogenetic effects in ocular diseases, including those of the cornea, uvea, and retinal blood vessels. Finally, we describe the therapeutic implications of targeting NETs in such conditions.

A corneo-retinal hypercitrullination axis underlies ocular injury to nitrogen mustard

The vesicant sulfur mustard (SM) is a chemical warfare agent that causes acute and chronic injury to the cornea and proximal anterior segment structures. Despite clinical evidence of SM-exposure causing unexplained retinal deficits, there have been no animal studies conducted to examine the retinal toxicity of this vesciant. The cardinal hallmark of retinal response to stressors or injury is the activation of reactive gliosis, a cellular process largely governed by Müller glia. Previously we showed that corneal exposure to sodium hydroxide elicits rapid induction of reactive gliosis and results in retinal degeneration in a dose-related manner. Based on this evidence, we hypothesized that the vesicant nitrogen mustard (NM), an analog of SM, may also elicit reactive gliosis. To test this idea, we developed a mouse model of NM ocular injury and investigated corneal and retinal effects focusing on citrullination, a posttranslational modification (PTM) of proteins. This PTM was recently linked to alkali injury and has also been shown to occur in retinal degenerative conditions. Here, we demonstrate that corneal exposure to 1% NM causes a synchronous activation of citrullination in both the cornea and retina with hypercitrullination becoming apparent temporally and manifesting with altered cellular expression characteristics. A key finding is that ocular citrullination occurs acutely as early as 1-h post-injury in both the cornea and retina, which underscores a need for expeditious interception of this acute corneal and retinal response. Moreover, exploiting dose response and temporal studies, we uncoupled NM-induced retinal citrullination from its induction of retinal gliosis. Our findings demonstrate that hypercitrullination is a common corneo-retinal mechanism that sensitizes the eye to NM injury and suggests that counteracting hypercitrullination may provide a suitable countermeasure to vesicant injury.

Penetrating keratoplasty and glaucoma valve surgery in recurrent Mooren's disease: A multidisciplinary approach

INTRODUCTION AND IMPORTANCE

The case report highlights the challenges in managing recurrent Mooren's ulcer, a rare and severe form of peripheral ulcerative keratitis.

CASE PRESENTATION

A 49-year-old male, with bilateral Mooren's disease who underwent multiple surgical interventions for visual rehabilitation but developed disease recurrence in the left eye despite being on systemic and topical immunosuppression. The authors report successful long-term visual rehabilitation following a large-graft penetrating keratoplasty and Ahmed glaucoma valve implantation performed under immunosuppressive cover after adequate control of inflammation with intravenous Rituximab.

CLINICAL DISCUSSION

We discuss the traditionally poor survival of penetrating keratoplasty in refractory Mooren's disease due to the recurrence of the disease in the graft. Occurrence of secondary glaucoma is commonly seen in these eyes, which often requires combined filtration surgery and medical management. The first and second line systemic immunosuppression may be insufficient in adequately controlling the disease, and that intravenous monoclonal antibodies, such as Rituximab, may be a promising treatment modality in refractory Mooren's disease prior to embarking on any surgical intervention.

CONCLUSION

Overall, the case report highlights the importance of adequate control of inflammation and the use of immunosuppressive cover in achieving successful outcomes of PK and AGV surgery in Mooren's ulcer. The authors suggest that intravenous Rituximab may be a valuable addition to the management of refractory Mooren's disease, particularly prior to surgical intervention. However, as with any case report, the findings should be interpreted with caution and further research is needed to validate the efficacy of this treatment modality.

Proteomic profiling of human corneal stroma from long-term contact lens wearers reveals activation of inflammatory responses

PURPOSE

To investigate the association between proteomic changes and potential pathogenesis in the human cornea with respect to the duration of wearing soft contact lenses (SCLs).

METHODS

A total of 96 corneal stroma samples, obtained via small incision lenticule extraction (SMILE), were equally grouped according to the duration of wearing SCL: 0Y, did not wear SCL; 5Y, wore SCL for<5 years; 5-10Y, wore SCL for 5-10 years; O10Y, wore SCL for>10 years. Liquid chromatography-tandem mass spectrometry was used to identify and quantify protein profiles in the corneal stroma. Expression levels of CO1A1, CO4A1, NFKB1, and IL6RB were determined using western blot and immunohistochemistry analysis.

RESULTS

This study quantified a total of 5,668 proteins across samples and identified 2,379 differentially expressed proteins (DEPs) with significantly increased abundance in the three SCL-wearing groups compared with that in the non-SCL-wearing group. Compared with those in the 0Y group, the molecular functions of DEPs in the 5Y, 5-10Y, and O10Y groups were mainly related to translation regulator activity, antigen binding, peptidase inhibitor activity, participation in extracellular matrix (ECM) production, complement activation, and inflammatory responses. Pathway enrichment analysis of DEPs showed that the sphingolipid, phosphatidylinositol 3-kinase-protein kinase B, and hypoxia-inducible factor-1 signaling pathways were activated in the human corneal stroma after long-term SCL use.

CONCLUSIONS

Inflammation-related proteomic components in human corneal stroma increased after long-term use of SCL and may act as an essential factor in the molecular pathogenesis of corneal stroma damage.

The Role of Neutrophil Extracellular Traps in the Ocular System

Purpose: Neutrophils remain at the top of congenital and adaptive immune systems. The past 20 years witnessed a steep rise in the interest in neutrophil extracellular traps (NETs), which are a novel type of anti-pathogen mechanism coordinated with neutrophils. However, accumulating data revealed that excessive NETs in the host were associated with exacerbated inflammation, thrombosis, and autoimmunity. Increasing evidence found the participation of NETs in the pathophysiological process of many infectious and sterile diseases in the ocular system. Therefore, we discussed the role of neutrophil extracellular traps in the ocular system in this review.Methods: Articles were searched on PubMed, Embase and Web of science up to December 2021.Results: In this review, we exhibited the protective role of neutrophils patrolling the ocular surface from invading pathogens and their contribution to exacerbated inflammation and thrombogenesis in some ocular diseases. We also discussed the physiological and pathological processes of NET generation to identify novel biomarkers and therapeutic targets to interrupt immoderate NET formation and alleviate NET-induced harmful effects.Conclusions: Neutrophils and NETs are quite important for immune responses in the ocular system, while their negative effects on ocular tissue should also be emphasized, which could serve as novel biomarkers and potential therapeutic targets.

Immunohistochemical staining of immunoglobulin G in healthy equine, canine, and feline corneas

Objective

Establishing an immunohistochemical approach for semi‐quantitative assessment of the presence of immunoglobulin G (IgG) in equine, canine, and feline corneas.

Procedures

Healthy corneas of horses, dogs, and cats, euthanized because of a fatal disease or an unrecoverable trauma unrelated to and without a history of ophthalmic disease were formalin‐fixed, paraffin‐embedded, and determined to be pathomorphologically healthy by light microscopy. Automated immunohistochemistry was performed using primary antibodies against IgG, biotin‐conjugated secondary antibodies, and streptavidin‐peroxidase, as well as diaminobenzidine for visualization. After counterstaining with hematoxylin, epithelium, stroma, Descemet´s membrane (DM), and endothelium were semi‐quantitatively scored for the presence of IgG on a 4‐grade scale (0 = no, 1 = faint, 2 = medium, 3 = strong staining) by light microscopy.

Results

Corneal specimens of 20 horses (40 eyes) with a median age of 15.5 years (range 2–31 years), 12 dogs (21 eyes) with a median age of 10.0 years (range 4–16), and 13 cats (24 eyes) with a median age of 10.0 years (range 2–18) were included in the study. Different sexes and breeds were represented. In all corneas (100%), significant medium signal intensity in the stroma was observed. Variable immunosignal was obtained in epithelium, DM, and endothelium.

Conclusion

This method reproducibly allows for the detection of IgG in healthy equine, canine, and feline corneas, particularly stroma. Semi‐quantitative results evidence medium presence of IgG in the corneal stroma. Further research is needed to evaluate IgG presence in diseased corneas.