Superoxide anion radical as an indirect mediator in ocular inflammatory disease

Intravitreal injection of a superoxide-generating reaction mixture of xanthine oxidase and xanthine, either with or without rabbit plasma, was shown to be a mediator of an intense uveal and retinal inflammation in pigmented and albino rabbits. Controls of heat-inactivated xanthine oxidase with or without rabbit plasma, or plasma by itself, was without effect on ocular tissues. Xanthine alone as a control exhibited little or no inflammatory response. Controls of active xanthine oxidase by itself, or with rabbit plasma, produced a very strong inflammatory response that may represent enzymic reaction with endogenous xanthine. When the superoxide generating reaction mixture was given intravitreally the reaction began in the anterior segment within 16 hours and reached its peak after 2 days. The response in the posterior segment was delayed and did not become evident until after at least 24 hours, and may be due to the close proximity of the anterior chamber to the ciliary processes where cellular exudates first appear. Anterior segment uveitis began to recede after 4 days but posterior segment inflammation persisted beyond 6 days, and in many instances, led to retinitis, and retinal detachment. Superoxide dismutase was effectively used in vitro to quench superoxide in the reaction mixture but it did not prevent inflammatory reactions in vivo because it was found to possess strong toxic qualities of its own in ocular tissues. Other free radicals of oxygen, as well as hydrogen peroxide, can develop with the breakdown of superoxide, and cause tissue damage. A known ability of superoxide to convert a plasma precursor into a factor chemotactic for neutrophils may also cause superoxide production in situ by accumulating neutrophils. Because phagocytes are potential sources of superoxide, this study provides a good experimental model for studying the influence of oxygen free radicals in ocular inflammatory disease.     

Innate immunity of the ocular surface and ocular surface inflammatory disorders

Ocular surface epithelial cells selectively respond to microbial components and induce limited inflammation, whereas immune competent cells such as macrophages can recognize various microbial components through Toll-like receptors (TLRs), induce inflammation, and, thereby, exclude microbes. The difference between macrophages and ocular surface epithelial cells could be due to their dissimilarity in coexistence with commensal bacteria. The unique innate immune response of the ocular surface epithelium might contribute to its coexistence with commensal bacteria. Moreover, we suspect that some ocular surface inflammatory disorders might be caused by abnormality of the mucosal innate immunity. We considered the possibility that there is an association between Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN)--a severe variant of SJS--and a disordered innate immune response. In gene expression analysis of CD14 cells, we found that interleukin-4 receptor (IL-4R) gene expression was different between patients with SJS/TEN and normal control subjects upon lipopolysaccharide (LPS) stimulation: it was downregulated in the former and slightly upregulated in the latter. Furthermore, expression of mRNA specific for IkappaBzeta and interleukin (IL)-1alpha was lower in patients with SJS/TEN than in normal controls after 1-hour culture. We next performed single nucleotide polymorphism (SNP) association analysis of IL-4R, IkappaBzeta, and IL1alpha genes and TLR2 and TLR3--genes associated with innate immunity--in 80 Japanese patients with SJS/TEN and 160 Japanese healthy volunteers. IL4R SNP Gln551Arg (rs.1801275) (P = 0.0004), TLR3 rs.3775296T/G SNP (P = 0.0001) and TLR3 rs.3775290A/G SNP (P = 0.009) showed a significant association with SJS/TEN. IkappaBzeta SNP rs.595788G/A showed a weak inverse association (P = 0.04). Genetic and environmental factors may play a role in an integrated etiology of SJS/TEN, and there is possibly an association between SJS/TEN and a disordered innate immunity.     

Blink-related microtrauma: when the ocular surface harms itself

Superior limbic keratoconjunctivitis results mechanically from blinking under prolonged unphysiological conditions. The pathogenic process is known as blink-related microtrauma. This review aimed to explore the validity of a general theory that besides superior limbic keratoconjunctivitis, there may be other diseases of the ocular surface arising from mechanical microtrauma. A review of relevant clinical and microscopic lesions in a range of ocular surface disorders with possible mechanical aetiology was conducted. New terms were selected to facilitate understanding of such new aetiology. Besides superior limbic keratoconjunctivitis, other ocular surface disorders regarded as primarily derived from blink microtrauma are: other filamentary keratitides; blepharospasm and severe ptosis; canthal/palpebral froth; affections from disordered eyelid lining; and contact lens related damage. A group of secondarily microtraumatic disorders was identified, including the example of microtrauma impacting upon interpalpebral bulbar prominences. Superior limbic keratoconjunctivitis is the archetype of diseases affecting a unique combination; namely, the ocular surface conjoined with its lacrimal fluid. It is only one among many diseases actively generated within the confines of 'a self-harming surface'.     

Time course of rabbit ocular inflammatory response and mediator release after intravitreal endotoxin

An inflammatory response was elicited in the rabbit eye by intravitreal injection of endotoxin. The appearance in aqueous humor of selected metabolites of arachidonic acid metabolism at various times was correlated with the influx of protein and myeloperoxidase activity in the iris-ciliary body. After intravitreal injection of endotoxin, aqueous humor protein levels increased substantially within 2 hr. This aqueous humor protein increase occurred before a significant appearance of prostaglandin E2 (PGE2) in the aqueous humor. Myeloperoxidase activity in the iris-ciliary body, a measure of polymorphonuclear leukocyte (PMN) infiltration, showed little elevation until 6 hr after endotoxin injection and then increased rapidly through 24 hr. The appearance of the leukotriene B4 (LTB4) followed a similar time course: levels in the aqueous humor were partially elevated until 6 hr after endotoxin injection, when levels begin to rise rapidly. These findings are interpreted to demonstrate the dependence of PMN infiltration on the release and accumulation of LTB4; the initial breakdown of the blood-aqueous barrier and influx of protein appears to be independent of significant release of PGE2.     

The potential of lipid mediator networks as ocular surface therapeutics and biomarkers

In the last twenty years an impressive body of evidence in diverse inflammatory animal disease models and human tissues, has established polyunsaturated fatty acids (PUFA) derived specialized-pro-resolving mediators (SPM), as essential mediators for controlling acute inflammation, immune responses, wound healing and for resolving acute inflammation in many non-ocular tissues. SPM pathways and receptors are highly expressed in the ocular surface where they regulate wound healing, nerve regeneration, innate immunity and sex-specific regulation of auto-immune responses. Recent evidence indicates that in the eye these resident SPM networks are important for maintaining ocular surface health and immune homeostasis. Here, we will review and discuss evidence for SPMs and other PUFA-derived mediators as important endogenous regulators, biomarkers for ocular surface health and disease and their therapeutic potential.     

Assessing the ocular surface microbiome in severe ocular surface diseases

PurposeThere is growing evidence for a critical role of the microbiome in ocular health and disease. We performed a prospective, observational study to characterize the ocular surface microbiome (OSM) in four chronic ocular surface diseases (OSDs) and healthy controls.MethodsSterile swabs were used to collect samples from each eye of 39 patients (78 eyes). Sterile technique and multiple controls were used to assess contamination during DNA extraction, amplification and sequencing. Concurrent use of topical antibiotics, steroids, and bandage contact lenses (BCLs) was documented.ResultsDespite the low biomass of the ocular surface, 47/78 (60%) eyes sampled had positive sequencing reads. We observed that half of patients (8/17, 47%) had distinct microbiomes in each eye. Healthy controls had a Lactobacillus/Streptococcus mixture or significant Corynebacterium. Staphylococcus predominated in 4/7 (57%) patients with Stevens-Johnson Syndrome (SJS) in at least one eye, compared to 0/10 healthy controls. Interestingly, 8/11 (73%) eyes with SJS were using BCLs, including 4/5 (80%) eyes dominated by Staphylococcus. Lax eyelid syndrome (LES) and Dry Eye Disease (DED) patients had similar OSMs, with Corynebacterium being the most prevalent bacteria. Alpha diversity was higher in controls and ocular graft-vs-host (oGVHD) patients compared to the other OSDs.ConclusionsOnly 50% of the 39 patients had similar microbiomes in each eye. A majority of healthy eyes had a Lactobacillus/Streptococcus mix or Corynebacterium microbiome. Staphylococcus predominated in SJS, Lactobacillus in oGVHD, and Corynebacterium in DED and LES. There may be an association between different OSDs and the microbiome.     

环孢素A在眼表移植和角膜炎症中的应用

目的探讨环孢素A(Cyclosporine A，CsA)在眼表移植手术和炎症性疾病中的疗效和相关影响因素。方法通过106眼眼表手术(羊膜贴敷71眼、穿透性角膜移植20眼、指环形／全角膜上皮移植15眼)的术后用药和32眼角膜炎症性疾患(干燥性角结膜炎8例16眼、蚕蚀性角膜溃疡3例4眼、单疱角膜基质炎2例2眼、表层点状角膜病变7例10眼)的系统治疗观察，对临床疗效作回顾性研究。用药途径：穿透性角膜移植和指环形／全角膜上皮移植病例，术后口服CsA6w～8w，联合局部0．5％CsA滴眼剂3次～4次／d，持续用药8m～12m；羊膜贴敷者仅在术后0．5％CsA滴眼剂3次／d，持续用药8m～12m；角膜炎症性病例中蚕蚀性角膜溃疡4眼中3眼采用病灶切除后羊膜贴敷联合局部用药，1眼单用0．5％CsA局部滴眼；其他病例按病种不同，分别应用0．1％～0．5％CsA局部滴眼3～4次／d联合相关对因治疗结果135眼治疗者中有128眼随访6m～36m．7眼为新近观察病例，仅随访3m～6m：35眼穿透性角膜移植和指环形／全角膜上皮移植术中，仅3眼因移植排斥致角膜血管化，32眼透明愈合，获得91．4％的移植成功率；所有重症烧伤羊膜贴敷患者，术后眼表重新上皮化且未遗留睑球粘连。70％以上病例瞳孔区角膜维持透明而重获有用视力；角膜炎症性疾病中，4眼蚕蚀性溃疡随访24m～36m均未复发，单疱角膜基质炎和表层点状角膜病变病例均获临床痊愈，干眼症患者症状缓解，Seehirmer实验泪液分泌改善。结论环孢素A是一种亲脂性多肽，易于透过角膜上皮并蓄积于角膜基质；通过选择性抑制辅助性T淋巴细胞发挥良好的免疫抑制和抗炎作用，对眼表移植手术和炎症性眼表疾患有出色的治疗功效。     

Boston ocular surface prosthesis: an Indian experience

Context:

Boston ocular surface prosthesis (BOSP) is a scleral contact lens used in the management of patients who are rigid gas permeable (RGP) failures as with corneal ectasias such as keratoconus and in those patients who have ocular surface disease such as Stevens–Johnson syndrome (SJS).

Aim:

To report utilization of BOSP in a tertiary eye care center in India.

Materials and Methods:

We retrospectively reviewed charts of 32 patients who received BOSP from July 2008 to May 2009. Indications for fitting these lenses, improvement in visual acuity (VA) before and after lens fitting and relief of symptoms of pain and photophobia were noted. Paired t-test was used for statistical analysis using SPSS version 16.0 for Windows.

Results:

Thirty-two patients (43 eyes) received these lenses. These consisted of 23 eyes of 17 patients who failed RGP trials for irregular astigmatism and corneal ectasia such as keratoconus and post radial keratotomy and scar and 20 eyes of 15 patients with SJS. Mean age of RGP failures was 27.94 years. Pre- and post-BOSP wear mean LogMAR VA was 1.13 and 0.29, respectively, in RGP failures. The P value was statistically significant (P < 0.001). In patients with SJS, LogMAR VA was 0.84 ± 0.92 before and 0.56 ± 0.89 after lens wear. The P value was statistically significant (P < 0.001). VA improved by >2 lines in 7/20 eyes (35%) with SJS, with improvement in symptoms.

Conclusion:

BOSP improves VA in patients who have irregular astigmatism as in ectasias and RGP failures and improves vision and symptoms in patients with SJS.     

Corneal expression of the inflammatory mediator CAP37

PURPOSE: CAP37 is a polymorphonuclear neutrophil (PMN)-derived inflammatory protein with potent antibiotic and chemotactic activity. To further investigate the biological significance of CAP37 in infection and inflammation, a well-characterized in vivo rabbit model of bacterial keratitis was selected to study its contribution to host defenses. METHODS: One hundred colony-forming units of log phase Staphylococcus aureus was injected intrastromally. Eyes were enucleated at 5 to 25 hours after infection and CAP37 detected by immunohistochemistry. To identify the mechanism of CAP37 upregulation in corneal epithelium, in vitro studies using immortalized human corneal epithelial cells (HCECs) were undertaken to determine whether proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), induce CAP37. Because adhesion of leukocytes is important in leukocyte-epithelium interactions, the effect of CAP37 on expression of intercellular adhesion molecule (ICAM)-1 on HCECs was determined by flow cytometry. RESULTS: Strong staining for CAP37 was demonstrated in the corneal epithelium, stromal fibroblasts, ciliary epithelium, related limbus, ciliary vascular endothelium, and bulbar conjunctiva in rabbits injected with S. aureus. The most dramatic expression of CAP37 aside from that in the PMNs occurred in the corneal epithelium. The in vitro studies suggest that CAP37 induction is regulated by TNF-alpha and IL-1beta. In addition, ICAM-1 expression on HCECs was increased in response to CAP37. Molecular cloning of corneal epithelial CAP37 indicated strong sequence identity with an extensive region of PMN-CAP37. CONCLUSIONS: The findings in this study describe the extraneutrophilic expression of CAP37 in response to infection and suggest a role for CAP37 in host defense against infection in the eye.     

Dry eye disease: an immune-mediated ocular surface disorder

Dry eye disease is a multifactorial disorder of the tears and ocular surface characterized by symptoms of dryness and irritation. Although the pathogenesis of dry eye disease is not fully understood, it is recognized that inflammation has a prominent role in the development and propagation of this debilitating condition. Factors that adversely affect tear film stability and osmolarity can induce ocular surface damage and initiate an inflammatory cascade that generates innate and adaptive immune responses. These immunoinflammatory responses lead to further ocular surface damage and the development of a self-perpetuating inflammatory cycle. Herein, we review the fundamental links between inflammation and dry eye disease and discuss the clinical implications of inflammation in disease management.