Arachidonic acid cascade and platelet-activating factor in the network of eye inflammatory mediators: therapeutic implications in uveitis

Next-generation nanomaterials: advancing ocular anti-inflammatory drug therapy

Ophthalmic inflammatory diseases, including conjunctivitis, keratitis, uveitis, scleritis, and related conditions, pose considerable challenges to effective management and treatment. This review article investigates the potential of advanced nanomaterials in revolutionizing ocular anti-inflammatory drug interventions. By conducting an exhaustive analysis of recent advancements and assessing the potential benefits and limitations, this review aims to identify promising avenues for future research and clinical applications. The review commences with a detailed exploration of various nanomaterial categories, such as liposomes, dendrimers, nanoparticles (NPs), and hydrogels, emphasizing their unique properties and capabilities for accurate drug delivery. Subsequently, we explore the etiology and pathophysiology of ophthalmic inflammatory disorders, highlighting the urgent necessity for innovative therapeutic strategies and examining recent preclinical and clinical investigations employing nanomaterial-based drug delivery systems. We discuss the advantages of these cutting-edge systems, such as biocompatibility, bioavailability, controlled release, and targeted delivery, alongside potential challenges, which encompass immunogenicity, toxicity, and regulatory hurdles. Furthermore, we emphasize the significance of interdisciplinary collaborations among material scientists, pharmacologists, and clinicians in expediting the translation of these breakthroughs from laboratory environments to clinical practice. In summary, this review accentuates the remarkable potential of advanced nanomaterials in redefining ocular anti-inflammatory drug therapy. We fervently support continued research and development in this rapidly evolving field to overcome existing barriers and improve patient outcomes for ophthalmic inflammatory disorders.

Analysis of differentially expressed genes in individuals with noninfectious uveitis based on data in the gene expression omnibus database

Noninfectious uveitis (NIU), an intraocular inflammation caused by immune-mediated reactions to eye antigens, is associated with systemic rheumatism and several autoimmune diseases. However, the mechanisms underlying the pathogenesis of uveitis are poorly understood. Therefore, we aimed to identify differentially expressed genes (DEGs) in individuals with NIU and to explore its etiologies using bioinformatics tools. GSE66936 and GSE18781 datasets from the gene expression omnibus (GEO) database were merged and analyzed. Functional enrichment analysis was performed, and protein-protein interaction (PPI) networks were constructed. A total of 89 DEGs were identified. Gene ontology (GO) enrichment analysis identified 21 enriched gene sets. Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis identified four core enriched pathways: antigen processing and expression signaling, natural killer (NK) cell-mediated cytotoxicity signaling, glutathione metabolic signal transduction, and arachidonic acid metabolism pathways. PPI network analysis revealed an active component-target network with 40 nodes and 132 edges, as well as several hub genes, including CD27, LTF, NCR3, SLC4A1, CD69, KLRB1, KIR2DL3, KIR3DL1, and GZMK. The eight potential hub genes may be associated with the risk of developing NIU. NK cell-mediated cytotoxicity signaling might be the key molecular mechanism in the occurrence and development of NIU. Our study provided new insights on NIU, its genetics, molecular pathogenesis and new therapeutic targets.

Dexamethasone for Severe COVID-19: How Does It Work at Cellular and Molecular Levels?

The coronavirus disease 2019 (COVID-19) caused by infection of the severe respiratory syndrome coronavirus-2 (SARS-CoV-2) significantly impacted human society. Recently, the synthetic pure glucocorticoid dexamethasone was identified as an effective compound for treatment of severe COVID-19. However, glucocorticoids are generally harmful for infectious diseases, such as bacterial sepsis and severe influenza pneumonia, which can develop respiratory failure and systemic inflammation similar to COVID-19. This apparent inconsistency suggests the presence of pathologic mechanism(s) unique to COVID-19 that renders this steroid effective. We review plausible mechanisms and advance the hypothesis that SARS-CoV-2 infection is accompanied by infected cell-specific glucocorticoid insensitivity as reported for some other viruses. This alteration in local glucocorticoid actions interferes with undesired glucocorticoid to facilitate viral replication but does not affect desired anti-inflammatory properties in non-infected organs/tissues. We postulate that the virus coincidentally causes glucocorticoid insensitivity in the process of modulating host cell activities for promoting its replication in infected cells. We explore this tenet focusing on SARS-CoV-2-encoding proteins and potential molecular mechanisms supporting this hypothetical glucocorticoid insensitivity unique to COVID-19 but not characteristic of other life-threatening viral diseases, probably due to a difference in specific virally-encoded molecules and host cell activities modulated by them.

Leukotriene B4 receptors as therapeutic targets for ophthalmic diseases

Leukotriene B₄ (LTB₄) is an inflammatory lipid mediator produced from arachidonic acid by multiple reactions catalyzed by two enzymes 5-lipoxygenase (5-LOX) and LTA₄ hydrolase (LTA₄H). The two receptors for LTB₄ have been identified: a high-affinity receptor, BLT1, and a low-affinity receptor, BLT2. Our group identified 12(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (12-HHT) as a high-affinity BLT2 ligand. Numerous studies have revealed critical roles for LTB₄ and its receptors in various systemic diseases. Recently, we also reported the roles of LTB₄, BLT1 and BLT2 in the murine ophthalmic disease models of mice including cornea wound, allergic conjunctivitis, and age-related macular degeneration. Moreover, other groups revealed the evidence of the ocular function of LTB₄. In the present review, we introduce the roles of LTB₄ and its receptors both in ophthalmic diseases and systemic inflammatory diseases. LTB₄ and its receptors are putative novel therapeutic targets for systemic and ophthalmic diseases.

Topical non-steroidal anti-inflammatory agents for diabetic cystoid macular oedema

BACKGROUND

Diabetic cystoid macular oedema (CMO) is a condition which involves fluid accumulation in the inner portion of the retina. It often follows changes in retinal blood vessels which enhance the fluid to come out of vessels. Although it may be asymptomatic, symptoms are primarily painless loss of central vision, often with the complaint of seeing black spots in front of the eye.It is reported that CMO may resolve spontaneously, or fluctuate for months, before causing loss of vision. If left untreated or undiagnosed, progression of CMO may lead to permanent visual loss.It has been noted that patients with diabetic retinopathy have elevated inflammatory markers, and therefore it is likely that inflammation aids in the progression of vascular disease in these patients. Several topical non-steroidal anti-inflammatory drugs (NSAIDs) such as ketorolac 0.5%, bromfenac 0.09%, and nepafenac 0.1%, have therefore also been used topically to treat chronic diabetic CMO. Hence this review was conducted to find out the effects of topical NSAIDs in diabetic CMO.

OBJECTIVES

To assess the effects of topical non-steroidal anti-inflammatory drugs (NSAIDs) for diabetic cystoid macular oedema (CMO).

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2015), EMBASE (January 1980 to January 2015), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to January 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 12 January 2015.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs investigating the effects of topically applied NSAIDs in the treatment of people with diabetic CMO aged 18 years of age or over.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and screened all available titles and abstracts for inclusion. There were no discrepancies and we did not have to contact trial investigators for missing data.

MAIN RESULTS

We did not identify any RCTs matching the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

The review did not identify any RCTs investigating the effects of topical NSAIDs in the treatment of diabetic CMO. Most of the studies identified through the electronic searches had been conducted to analyse the effect of topical NSAIDs for pseudophakic CMO.In the absence of high quality evidence, clinicians need to use their clinical judgement and other low level evidence, such as observational non-randomised trials, to decide whether to use topical NSAIDs in cases of diabetic CMO.More research is needed to better understand the cause of this condition and its pathophysiology. This systematic review has identified the need for well designed, adequately powered RCTs to assess possible beneficial and adverse effects of topical NSAIDs in people with diabetic CMO. Future trials should aim to include a large sample size with an adequate follow-up period of up to one year.

Treatment of cystoid macular edema with the new-generation NSAID nepafenac 0.1%

Purpose:

To describe the use of nepafenac 0.1% for cystoid macular edema (CME).

Methods:

This was a multicenter retrospective review of 22 CME cases (20 patients) treated with nepafenac 0.1% (six with concomitant prednisolone acetate 1%) from December 2005 to April 2008: three acute pseudophakic CME cases, 13 chronic/recalcitrant pseudophakic CME cases, and six cases of uveitic CME. Pre- and post-treatment retinal thickness and visual acuity were reported.

Results:

Following treatment for six weeks to six months, six eyes with uveitic CME showed a mean retinal thickness improvement of 227 ± 168.1 μm; mean best-corrected visual acuity (BCVA) improvement was 0.36 ± 0.20 logMAR. All three cases of acute pseudophakic CME improved after four to 10 weeks of nepafenac, with a mean improvement in retinal thickness of 134 ± 111.0 μm. BCVA improved in two patients (0.16 and 0.22 logMAR) but not in the third due to underlying retinal pigment epithelium changes. Thirteen eyes with chronic/recalcitrant pseudophakic CME demonstrated a mean improvement in retinal thickness of 178 ± 128.7 μm after nepafenac and mean BCVA improvement of 0.33 ± 0.19 logMAR.

Conclusion:

The positive outcomes of these 22 eyes strongly suggest that nepafenac 0.1% is a promising drug for the treatment of CME. Additional study under randomized controlled conditions is warranted.

Establishment of a prediction method for premature rupture of membranes in term pregnancy using active ceruloplasmin in cervicovaginal secretion as a clinical marker

AIM

Term pregnancy complicated by premature rupture of membranes (PROM) is thought to be associated in part with subclinical infection, and places mothers and neonates at an increased risk for several complications. Therefore, perinatal care would be greatly helped if a reliable clinical measure were available for predicting the incidence of PROM.

METHODS

One hundred and ninety-six pregnant women who consented to enter this study were screened using a method developed to assess active ceruloplasmin in cervicovaginal secretion as a clinical marker for predicting the incidence of PROM. Cervicovaginal secretions were obtained from the cervical canal at about 36 weeks of pregnancy. The active ceruloplasmin level in the cervicovaginal secretion was measured using an original enzyme-linked immunoabsorbent assay.

RESULTS

Of 196 women, 27 women (13.8%) developed PROM and 169 women (86.2%) did not develop PROM. Active ceruloplasmin in the cervicovaginal secretion was significantly higher in the PROM group than in the non-PROM group (P < 0.001). Analysis using receiver-operating characteristic curves showed that the active ceruloplasmin level (1420.0 ng/mL) proved to be the proper cut-off value to best predict the incidence of PROM.

CONCLUSION

Active ceruloplasmin in the cervicovaginal secretion might be a reliable clinical marker for term PROM.

Effects of L-NAME and timolol on aqueous IL-1beta, IL-6, IL-8, TNF-alpha and NO levels after Nd:YAG laser iridotomy in rabbits

PURPOSE

Pro-inflammatory cytokines are produced by tissues and play a vital role in the host inflammatory response and uveitis. Nitric oxide (NO) can be produced in large amounts as a response to experimentally-induced uveitis or cytokines. In this study, we measured the levels of pro-inflammatory cytokines such as interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor (TNF)-alpha and free-radical in aqueous humor after Nd:YAG laser iridotomy in rabbits, and investigated whether timolol maleate an anti-glaucoma drug, or a NO synthase inhibitor, NG-nitro-L-arginine methyl esther (L-NAME) had an inhibitory effect on these molecules, since L-NAME is a known anti-inflammatory agent in rabbits.

METHODS

Bilateral experimental Nd:YAG laser iridotomy (power 7.5 mJ, mode single burst, aiming beam 4) was performed on 18 rabbits under general plus topical anesthesia. Aqueous humor samples were taken by clear corneal paracentesis preoperatively, and 1 and 24 h postoperatively. Six rabbits (12 eyes) were given bilateral topical timolol maleate 0.5% (Timoptic) drop b.i.d. (group 1), six rabbits (12 eyes) received bilateral 0.1 ml subconjuntival injections of L-NAME (150 mg/kg) (group 2), and six rabbits (12 eyes) were treated with topical balanced salt solution (BSS) b.i.d. (control). RESULTS. Preoperative cytokine and NO levels were comparable in the three groups, with no significant differences. In addition, there was no significant difference in baseline cytokine levels between the right and left eyes. In all groups, pre- and postoperative mean IL-1beta levels were below the detection limit of the assay (<5.0 pg/ml). In the control group, postoperative mean IL-6, IL-8 and NO levels were significantly higher after Nd:YAG laser iridotomy than before (for each, p < 0.01). Timolol and L-NAME both inhibited the rise in IL-8 and TNF-alpha levels. Timolol also inhibited the rise in IL-6 but not NO. L-NAME had an inhibitory effect against NO, but not IL-6.

CONCLUSIONS

L-NAME has an inhibitory effect on IL-8, TNF-alpha and NO, but not on IL-6. Timolol had inhibitory effects on IL-6, IL-8 and TNF-alpha, but not on NO. These preliminary experimental results might help in assssing the effect of Nd:YAG laser iridotomy in aqueous humor, and to understand the inhibitory effects of timolol and L-NAME against these molecules.

Comparison of the effects of argon and neodymium:YAG laser iridotomy on cytokines in the rabbit aqueous humor

PURPOSE

We compared the effects in rabbits of iridotomy using the argon or Nd:YAG laser on cytokines such as interleukin 1-beta (IL-1beta), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor-alpha (TNF-alpha).

METHODS

Twenty pigmented rabbits (20 eyes) underwent argon and Nd:YAG iridotomy under general and topical anesthesia. Group 1 (10 right eyes) was treated with the argon laser and group 2 (10 right eyes) with the Nd:YAG laser, using an equal number of shots and the same laser parameters for each group. Left eyes in both groups were evaluated as controls. Aqueous humor specimens were collected from each eye preoperatively and 1 and 3 days postoperatively.

RESULTS

Aqueous IL-6 and TNF-alpha levels rose more on day 1 in the Nd:YAG group than the argon group. IL-6 and TNF-alpha levels were significantly higher on days 1 and 3 than the pre-operative and control levels (p<0.05). TNF-alpha levels on day 1 were significantly lower in the Nd:YAG than the argon group. There were no significant differences between the two laser groups for IL-6 on days 1 and 3. IL-1beta and IL-8 did not change

CONCLUSIONS

Our findings suggest that cytokines, particularly IL-6 and TNF-alpha, may be inflammatory mediators in the early inflammation following argon and Nd:YAG laser iridotomies. These results also indicate that cytokines contribute to the acute effects of Nd:YAG and argon laser applications on inflammation.

Oral vitamins C and E as additional treatment in patients with acute anterior uveitis: a randomised double masked study in 145 patients

AIM

To investigate the effect of additional oral vitamins C and E on acute anterior uveitis.

METHODS

A placebo controlled double masked study on the effect of vitamin C 500 mg in combination with vitamin E 100 mg twice daily in 145 patients with acute anterior uveitis. As a primary end point variable, laser cell/flare measurements were performed. Best corrected and stenopeic visual acuity (VA) testing and clinical variable scores were measured.

RESULTS

Laser flare measurements (ph/s) before treatment were 207.1 (SD 258) in the vitamin group and 143.6 (156) in the placebo group. After 3 days corresponding values were 80.2 (129) and 54.7 (82), after 7 days 89.2 (187) (12.5) and 85.8 (208), after 14 days 47.1 (109.5) and 40.5 (116) after 28 days 23.1 (53.6) and 23.1 (48), and after 56 days 15.6 (26) and 15.3 (17). There was no significant difference in time trend between the two treatment groups (RMANOVA; p = 0.53). Baseline VA (logMAR) was 0.106 (0.241) in the vitamin group and 0.128 (0.456) in the placebo group. VA after 3 days was 0. 236 (0.293) and 0.344 ( 0.489), after 7 days 0.204 (0.292) and 0.292 (0.479), after 14 days 0.162 (0.274) and 0.193 (0.454), after 28 days 0.096 (0.232) and 0.158 (0.436), and 0.026 (0.213) and 0.106 (0. 437) after 56 days. Although no significant difference in time trend was detected, evaluation of the VA data of the last time point (56 days) by means of the Mann-Whitney test showed a significantly better VA in the vitamin group (p = 0.01).

CONCLUSIONS

There was no significant effect of vitamins C and E on laser flare measurements. The significant effect of the oral vitamins on visual acuity at 8 weeks after start of the oral vitamins C and E may indicate a protective effect in patients with acute anterior uveitis.

Effects of NG-nitro L-arginine and corticosteroids on aqueous humor levels of nitric oxide and cytokines after cataract surgery

PURPOSE

To assess the efficacy of nitric oxide synthesis (NOS) inhibitor, topical steroids, and nonsteroidal anti-inflammatory drugs on aqueous levels of nitric oxide (NO) and cytokines after cataract surgery.

SETTING

Research Laboratory, Inonu University Turgut Ozal Medical Center, Malatya, Turkey.

METHODS

Fifteen rabbits had intercapsular phacoemulsification and were randomly divided into 3 treatment groups: Group 1 was treated with topical prednisolone acetate 1% drops 5 times a day for 1 week; Group 2, flurbiprofen 0.03% drops 5 times a day for 1 week; Group 3, a 0.1 cc subconjunctival injection of NG-nitro L-arginine (L-NAME) (150 mg/kg) 1 day and 3 days after surgery. Three rabbits serving as controls received a subconjunctival injection of an equal volume of balanced salt solution (BSS) at the same times as the L-NAME injections. Aqueous humor specimens were collected from each eye to determine NO and cytokine levels including interleukin-1-beta (IL-1 beta), interleukin-2R (IL-2R), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

The levels of IL-1 beta and IL-6 were higher in Group 2 and the control group than in Groups 1 and 3 at all times. The differences were not statistically significant (P < .05). Nitric oxide and TNF-alpha levels in Groups 1 and 3 were significantly lower than in Groups 2 and the controls 1, 3, and 7 days postoperatively (P < .05).

CONCLUSION

These findings suggest a strong inhibitory effect of NOS inhibitors and corticosteroids on aqueous levels of TNF-alpha and NO and no inhibitory effect on IL-1 beta and IL-6 levels after cataract surgery.

Host/parasite interactions in bacterial endophthalmitis

Bacterial infections within the eye arise as complications of intraocular surgery, penetrating injury, or hematogenous spread from distant anatomical sites. Because: 1) the interior surfaces of the eye are lined with sensitive, nonregenerating tissues, 2) the inner chambers of the eye are relatively sequestered from circulating immunological components, 3) the integrity of blood-ocular barriers provides poor penetration of systemically administered antibiotics, and 4) aqueous and vitreous humor represent rich, relatively acellular culture media; endophthalmitis often progresses rapidly and total loss of vision frequently results. Years of clinical experience have shown that current therapies for endophthalmitis, including antimicrobials, antiinflammatory agents, and vitrectomy, are frequently unsuccessful in ameliorating destruction of intraocular tissues. While bacterial and host factors were thought to play key roles in the course and severity of endophthalmitis, it is only recently that their contributions have been experimentally defined. Molecular-based techniques are gaining increased use in the study of infectious eye diseases. Current findings regarding the host/parasite interactions within the eye are reviewed, and a resulting integrative model of the natural course of endophthalmitis proposed. A molecular-level understanding of the roles of both bacterial and host factors during endophthalmitis will likely reveal potential targets for therapeutic intervention aimed at salvaging vision.

Immunomodulating activity of allopurinol in experimental lens-induced uveitis

PURPOSE

The aim of this study was to evaluate the immunomodulating activity of allopurinol using a model of lens-induced uveitis (LIU) and to compare these effects to those of steroids.

METHODS

We tested the sera of both LIU and control rats against western blots (WB) of SDS-PAGE separations of protein fractions from normal and LIU rat lenses. These blots were scanned using digital image analysis. A newly developed technique was used to compare the complex autoantibody (AAB) repertoires. Five groups of LIU rats were investigated: no treatment; single doses of methylprednisolone (MPR; 7.5 mg/kg body wt.i.v.); allopurinol (AL; 50 mg/kg body wt. i.v.); a combination of both drugs (AL and MPR); repeated application of AL (ALFR; 50 mg/kg body wt.i.v. every 2 weeks during the immunization period and a daily dose of approx. 25 mg/kg body wt. orally).

RESULTS

Immunization induced complex antibody repertoires against lens proteins. Antibody repertoires of LIU rats were identical, regardless of whether the proteins were obtained from control, uveitis eyes, or corresponding healthy eyes of the same individual. AL showed a dose-dependent immunological effect in LIU treatment. Given as a single dose, AL revealed no significant change in the AAB repertoire; however, ALFR showed very clear modification of the AAB repertoires compared to both controls and rats receiving steroids.

CONCLUSIONS

These results suggest dose-dependent effects of allopurinol in LIU treatment. Repeated application during the immunization period induced a strong immunomodulating effect of AL that was not observed after single doses.

Effects of allopurinol and steroids on inflammation and oxidative tissue damage in experimental lens induced uveitis: a biochemical and morphological study

AIMS

To evaluate the effects of allopurinol in lens induced uveitis (LIU) by morphological methods and to compare these effects with those of steroids and a combination of both drugs biochemically and morphologically.

METHODS

Lipid peroxides (LPO) of the retinal tissue were determined by two different methods (thiobarbituric acid assay (TBA) and high performance liquid chromatography expressed as malondialdehyde-like substances). Myeloperoxidase (MPO) activity in the iris/ciliary body complex was analysed spectrophotometrically. Histological changes on three morphological levels of LIU eyes were evaluated.

RESULTS

Both allopurinol and the combination of allopurinol/prednisolone led to a significant reduction in the increaed retinal LPO values. Prednisolone only revealed significant effects on retinal LPO when being measured with the TBA method. MPO activity in iris and ciliary body was significantly reduced in all therapy groups. The morphological evaluation of the sections by two masked investigators revealed a significant reduction (p < 0.05) in the inflammation score in all therapy groups. Morphometric studies using the QUANTIMED system (Leica, Cambridge) showed significantly reduced values (p < 0.05) in the allopurinol group and in the group receiving prednisolone and allopurinol. Prednisolone alone did not lead to a significant reduction in the values.

CONCLUSIONS

The findings show that both allopurinol and steroids exert positive effects on the variables determined in LIU. The effects of steroids are believed to be mostly due to their direct action on inflammatory cells. The recently reported scavenging effects of methylprednisolone should play a minor role in this disease model. Allopurinol and oxypurinol act as direct scavengers of free radicals and hypochlorous acid, which is produced via MPO catalysis, thus leading to a reduction in tissue inflammation and tissue damage.