The effects of oral and topical corticosteroid in rabbit corneas

Identification and Validation of the Pyroptosis-Related Hub Gene Signature and the Associated Regulation Axis in Diabetic Keratopathy

Background

Diabetic keratopathy (DK) poses a significant challenge in diabetes mellitus, yet its molecular pathways and effective treatments remain elusive. The aim of our research was to explore the pyroptosis-related genes in the corneal epithelium of the streptozocin-induced diabetic rats.

Methods

After sixteen weeks of streptozocin intraperitoneal injection, corneal epithelium from three diabetic rats and three normal groups underwent whole-transcriptome sequencing. An integrated bioinformatics pipeline, including differentially expressed gene (DEG) identification, enrichment analysis, protein-protein interaction (PPI) network, coexpression, drug prediction, and immune deconvolution analyses, identified hub genes and key drivers in DK pathogenesis. These hub genes were subsequently validated in vivo through RT-qPCR.

Results

A total of 459 DEGs were screened out from the diabetic group and nondiabetic controls. Gene Set Enrichment Analysis highlighted significant enrichment of the NOD-like receptor, Toll-like receptor, and NF-kappa B signaling pathways. Intersection of DEGs and pyroptosis-related datasets showed 33 differentially expressed pyroptosis-related genes (DEPRGs) associated with pathways such as IL-17, NOD-like receptor, TNF, and Toll-like receptor signaling. A competing endogenous RNA network comprising 16 DEPRGs, 22 lncRNAs, 13 miRNAs, and 3 circRNAs was constructed. After PPI network, five hub genes (Nfkb1, Casp8, Traf6, Ptgs2, and Il18) were identified as upregulated in the diabetic group, and their expression was validated by RT-qPCR in streptozocin-induced rats. Immune infiltration characterization showed that diabetic corneas owned a higher proportion of resting mast cells, activated NK cells, and memory-resting CD4 T cells. Finally, several small compounds including all-trans-retinoic acid, Chaihu Shugan San, dexamethasone, and resveratrol were suggested as potential therapies targeting these hub genes for DK.

Conclusions

The identified and validated hub genes, Nfkb1, Casp8, Traf6, Ptgs2, and Il18, may play crucial roles in DK pathogenesis and serve as therapeutic targets.

Dry Eye Disease: What Is the Role of Vitamin D?

Dry eye disease (DED) is a multifactorial condition resulting from reduced tear secretion from the lacrimal glands, increased tear water evaporation or the production of poor-quality tears. Such tear instability can lead to inflammation and damage of the ocular surface, as well as to abnormal nociception. Historically, tear substitutes and corticosteroids have been the bastion of DED therapy, but a substantial number of patients still suffer from residual symptoms even after being treated with traditional treatments. Aiming to find safe and effective alternative therapies, recent efforts have been focused on the role of vitamin D in the cellular physiology of the eye. Possibly because of its positive effect in modulating the immune and inflammatory responses, the systemic supplementation of vitamin D seems, indeed, to be an effective therapeutic strategy, especially, but not only, for patients affected by DED that does not respond to conventional treatments. In this context, this review focuses on the literature reporting on the pathogenesis and treatment of DED, with a special emphasis on the recent investigations reporting on the potential role of the systemic administration of vitamin D as a therapeutic approach in the management of such condition.

Corneal perforation associated with ocular graft-versus-host disease

Corneal perforation is a rare and serious complication of ocular graft-versus-host disease (oGVHD) patients. This study was to retrospectively report seven corneal perforation patients after allogeneic hematopoietic stem cell transplantation (HSCT). Demographic, hematologic, and ophthalmological data of patients were clarified in detail. Nine eyes of seven corneal perforation patients were clarified (Cases 3 and 6 were bilateral and the others are unilateral). All the cases had other affected GVHD organs, especially skin involvement. The duration between HSCT and corneal perforation was usually long with 21 (17–145) months as median interval, whereas the duration between oGVHD diagnosis and corneal perforation was relatively shorter with 4 (2–81) months as median interval. Most patients presented to ophthalmology department with poor visual acuity, BUT and Schirmer’s test. Eyelid marginal hyperemia and irregularity were observed in most corneal perforation eyes. Keratoplasty or conjunctival flap covering (CFC) surgeries was performed after corneal perforation. After a long-term follow-up for most patients (median 21 months, range: 2–86 months), only two eyes of two patients (22.22%) had a final BCVA of 20/100 or better. Patients involved in both cutaneous GVHD and blepharitis indicate the aggressive development of oGVHD. Early diagnosis, long-term follow-up, and effective multi-disciplinary treatments for oGVHD patients are essential. Corticosteroids and immunosuppressor remain essential, whereas the use of topical corticosteroids should be carefully considered in corneal ulceration patients. In addition, appropriate surgeries should be performed to control oGVHD development in time.

Gomisin M2 alleviates psoriasis‑like skin inflammation by inhibiting inflammatory signaling pathways

Psoriasis, a chronic inflammatory skin disease, is characterized by the excessive proliferation and impaired differentiation of epidermal keratinocytes and is accompanied by the increased infiltration of inflammatory cells. The condition requires long‑term treatment and has no definitive cure. Hence, supplements and therapeutic agents have been intensely investigated. Gomisin M2 (GM2), a lignan extracted from Schisandra chinensis (Turcz). Baill. (Schisandraceae; S. chinensis), has demonstrated diverse pharmacological properties, including anticancer, anti‑inflammatory and antiallergic effects. Based on these findings, the present study examined the effects of GM2 on an imiquimod (IMQ)‑induced psoriasis mouse model and on keratinocytes stimulated by tumor necrosis factor (TNF)‑α and interferon‑γ. IMQ was topically applied to the back skin of mice for 7 consecutive days, and the mice were orally administered CD. These results showed that the oral administration of GM2 suppressed the symptoms of psoriasis, as evidenced by reductions in skin thickness, psoriasis area severity index scores for psoriasis lesions, transepidermal water loss and myeloperoxidase (MPO)‑associated cell infiltration. Furthermore, GM2 reduced the pathologically increased levels of immunoglobulin G2a, MPO and TNF‑α in the serum and T helper (Th)1 and Th17 cell populations in the spleen. GM2 decreased the gene expression of inflammatory‑related cytokines and chemokines and inhibited the expression of signal transducer and activator of transcription 1 and nuclear factor‑κB in the activated keratinocytes. These results suggested that GM2 from S. chinensis is a potential therapeutic candidate to alleviate psoriasis‑like skin inflammation.

Deterioration of wound healing and intense suppression of MMP-9 mRNA expression after short-term administration of different topical glucocorticoids or NSAIDs in an avian model of corneal lesions

Background

Corneal lesions are considered among important ophthalmic conditions in avian patients. Short-term outcome of using anti-inflammatory agents in corneal lesions of birds are not well-described.

Aims

The study evaluates effects of different anti-inflammatory agents on healing of alkali burn-induced corneal lesions in layer hens as an avian model.

Methods

Adult layers were randomly allocated into 7 groups (n=15) as follows: 1. Negative (normal) control (NC), and 2. Positive control (PC) with an experimentally induced-corneal lesion, 3-7. Birds with corneal lesions that were treated with dexamethasone, fluorometholone, prednisolone, ketorolac, or diclofenac eye-drops every 6 hours (QID) for 5 consecutive days.

Results

At the end of the experiment, proper healing was observed in PC group based on lesion area, while treated groups showed statistically larger lesion sizes as compared to PC birds (P<0.05). Although no significant difference was observed among groups, birds treated with ketorolac, diclofenac or fluorometholone had higher histopathological scores for most of the assayed parameters than other groups. Levels of tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) in corneal tissue of different groups were statistically the same. The mRNA expression of matrix metalloproteinase-9 (MMP-9) was increased 2.5 folds in PC group as compared to NC birds. However, birds treated with anti-inflammatory agents showed no detectable expression of MMP-9 mRNA.

Conclusion

Five days of topical administration of non-steroidal anti-inflammatory agents (NSAIDs) or glucocorticoids (GCs) is associated with suppression of MMP-9 mRNA expression in corneal tissue and detrimental effects on wound healing in layers with alkali burn-induced corneal ulcers.

Clinical tolerance of dexamethasone in New Zealand white rabbits

Rabbits have been a popular pet and research species world-wide. In many clinical and research situations, controlling inflammation is necessary for the health of these animals. One of the first drugs commonly employed in veterinary medicine to suppress inflammatory responses is corticosteroids. Unfortunately, steroid use in rabbits is not universally accepted as they are perceived, based on their potent immunosuppressant activity, to negatively impact quality of life. This is may be due, in part, to the lack of well-developed dosing protocols in these animals. This study evaluated the impact of a 5-day IM dexamethasone (Dex, 0.5 mg/kg) protocol on the immunity and clinical health of the New Zealand rabbit. Through two experiments separated by a 10-day washout period, experiment 1 comprised 5-days of dosing with bleedings on day 0, 3, 5 and 7, where experiment 2 consisted of 5-days of dosing with bleedings on day 0, 3 and 5. Animals were monitored twice daily for changes in clinical health. Hematology, T cell subset phenotype, leukocyte cell cycle, histopathology, phagocytosis and oxidative formation were evaluated. Consistent with other species, 5-day dosing with Dex suppressed leukocytes, in particular the T cells (p ≤ 0.003). Interestingly, rabbits failed to show any adverse clinical signs throughout the entire study. This would imply that a 5-day IM Dex (0.5 mg/kg) dosing protocol is well tolerated by New Zealand white rabbits and could be used in rabbits suffering from inflammatory conditions or disease as long as the animal's immune status is closely monitored.

Peripheral ulcerative keratitis

Peripheral ulcerative keratitis (PUK) is an inflammatory condition of the peripheral cornea with hallmark features of epithelial defects and stromal destruction as a result of a complex interplay of factors including host autoimmunity and the peculiar anatomic and physiologic features of the peripheral cornea and environmental factors. PUK may be the result of local or systemic causes and infectious or noninfectious causes. Arriving at a specific etiological diagnosis requires a meticulous clinical workup that may include a battery of laboratory and radiological investigations. Management by a team of internists or rheumatologists and ophthalmologists and judicious use of immunosuppressive agents may yield favorable results minimizing adverse effects. We review current clinical knowledge on the diagnosis and management of PUK.

Tear Film Pharmacokinetics and Systemic Absorption Following Topical Administration of 1% Prednisolone Acetate Ophthalmic Suspension in Dogs

The study aimed to determine the tear film pharmacokinetics following topical administration of 1% prednisolone acetate—assessing whether two drops would provide a superior kinetic profile compared to one drop—and to determine the fraction of an eye drop that reaches the systemic circulation in dogs. Two separate experiments were conducted in eight healthy Beagle dogs: (i) Instillation of 1 drop (35 μL) or 2 drops (70 μL) of 1% prednisolone acetate ophthalmic suspension in each eye, followed by tear collections with Schirmer strips from 0 to 720 min; (ii) Instillation of 1 or 2 drops of 1% prednisolone acetate in both eyes 4 times daily for 3 days, followed by blood collection 10–15 min after each topical administration on Day 3. Tear and blood samples were analyzed with high performance liquid chromatography to determine the levels of prodrug (prednisolone acetate), active metabolite (prednisolone) and total prednisolone (prednisolone_total = prodrug + active metabolite). Prednisolone levels represented 10 and 72% of prednisolone_total concentrations in tears and plasma, respectively, indicating a greater hydrolysis of prodrug in the blood vs. tear compartment. For eyes receiving one or two drops, tear film prednisolone_total concentrations were high (~3.1 mg/mL) immediately following topical administration but rapidly decreased by ~45% at 1 min and ~95% at 15 min. No differences were noted between 1 vs. 2 drops in tear film prednisolone_total concentrations (including maximal concentration, C_max) or residual drug levels in tears at any time point (P ≥ 0.097); however, instillation of 2 drops provided a higher average tear concentration (C_avg) and overall drug exposure to the ocular surface (AUC_last) over the 12-h sampling period (P = 0.009). Average plasma prednisolone_total concentration represented ≤ 2% of the dose applied to the ocular surface, and did not differ significantly for dogs receiving 1 drop (17 ng/mL) or 2 drops (20 ng/mL) 4 times daily for 3 days (P = 0.438). In sum, topical corticotherapy is beneficial for inflammatory conditions of the canine anterior segment given the relatively high concentrations achieved in tears, although caution is warranted to prevent unwanted local or systemic adverse effects.

Matching the Patient to the Intraocular Lens: Preoperative Considerations to Optimize Surgical Outcomes

The intraocular lens (IOL) selection process for patients requires a complex and objective assessment of patient-specific ocular characteristics, including the quality and quantity of corneal astigmatism, health of the ocular surface, and other ocular comorbidities. Potential issues that could be considered complications after surgery, including dry eye disease, anterior or epithelial basement membrane dystrophy, Salzmann nodular degeneration, and pterygium, should be addressed proactively. Aspheric IOLs are designed to eliminate the positive spherical aberration added by traditional IOLs to the pseudophakic visual axis. Spherical aberration may be a consideration with patient selection. Patient desire for increased spectacle independence after surgery is one of the main drivers for the development of multifocal IOLs and extended depth-of-focus (EDOF) IOLs. However, no one single multifocal or EDOF IOL suits all patients' needs. The wide variety of multifocal and EDOF IOLs, their optics, and their respective impact on patient quality of vision have to be understood fully to choose the appropriate IOL for each individual, and surgery has to be customized. Patients who have undergone previous LASIK or who have radial keratotomy and ocular pathologic features, including glaucoma, age-related macular degeneration, and epiretinal membrane, require specific considerations for IOL selection. Subjectively, patient-centered considerations, including visual goals, lifestyle, personality, profession, and hobbies, are key elements for the surgeon to assess and factor into an IOL recommendation. This holistic approach will help surgeons to achieve optimal surgical outcomes and to meet (and exceed) the high expectations of patients.

Systemic Paraquat Intoxication Presenting with Peripheral Ulcerative Keratitis: A Case Report and Literature Review

PURPOSE

To describe a rare case of systemic paraquat poisoning presenting with peripheral ulcerative keratitis.

METHODS

Case report and literature review.

RESULTS

Two days after a mouthful of paraquat ingestion, a 48-year-old man presented with painful oral ulcers, abnormal liver functions, and acute kidney injury, followed by the development of crescent-shaped corneal erosions along the limbus and progressive visual impairment in both eyes. Paraquat-induced peripheral ulcerative keratitis was suspected and the patient was treated with intensive topical steroid along with systemic steroid. He recovered completely with good visual outcomes after treatment.

CONCLUSIONS

Peripheral ulcerative keratitis is usually an immune-mediated ocular condition, and may be a complication associated with systemic paraquat poisoning. Proper diagnosis and adequate treatment are important for visual recovery.

The Immunological Basis of Dry Eye Disease and Current Topical Treatment Options

Homeostasis of the lacrimal functional unit is needed to ensure a well-regulated ocular immune response comprising innate and adaptive phases. When the ocular immune system is excessively stimulated and/or immunoregulatory mechanisms are disrupted, the balance between innate and adaptive phases is dysregulated and chronic ocular surface inflammation can result, leading to chronic dry eye disease (DED). According to the Tear Film and Ocular Surface Society Dry Eye Workshop II definition, DED is a multifactorial disorder of the ocular surface characterized by impairment and loss of tear homeostasis (hyperosmolarity), ocular discomfort or pain, and neurosensory abnormalities. Dysregulated ocular immune responses result in ocular surface damage, which is a further contributing factor to DED pathology. Several therapeutics are available to break the vicious circle of DED and prevent chronic disease and progression, including immunosuppressive agents (steroids) and immunomodulators (cyclosporine and lifitegrast). Given the chronic inflammatory nature of DED, each of these agents is commonly used in clinical practice. In this study, we review the immunopathology of DED and the molecular and cellular actions of current topical DED therapeutics to inform clinical decision making.

Plasma concentration of metformin and dexamethasone after administration through Osseogate

BACKGROUND

Osseogate is a novel drug delivery route through bone marrow involving a modified implant used as the drug delivery system. The purpose of this study was to evaluate the effects of individual drug physicochemical characteristics on the pharmacokinetic behavior when using the Osseogate as administration route.

METHODS

Implant-mediated drug delivery systems (IMDDS) were installed in a total of 18 rabbits. After complete healing, water-soluble metformin hydrochloride was administered to one group (n = 9) while poorly soluble dexamethasone was administered to the other group (n = 9). The release patterns of each group were monitored for two weeks by measuring the plasma concentration of each drug.

RESULTS

Both groups showed relative sustained release. However, metformin hydrochloride showed more rapid diffusion and early termination of drug release compared with dexamethasone.

CONCLUSIONS

The physicochemical properties of drugs significantly affected the release pattern through Osseogate. Further research is required to achieve controlled delivery using this route.

Peripheral Ulcerative Keratitis Associated with Autoimmune Disease: Pathogenesis and Treatment

Peripheral ulcerative keratitis (PUK) is type of crescent-shaped inflammatory damage that occurs in the limbal region of the cornea. PUK is always combined with an epithelial defect and the destruction of the peripheral corneal stroma. PUK may have a connection to systemic conditions, such as long-standing rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Wegener granulomatosis (WG), relapsing polychondritis, classic polyarteritis nodosa and its variants, microscopic polyangiitis, and Churg-Strauss syndrome. However, the most common connection is with RA, which is also the focus of this review. The pathogenesis of PUK is still unclear. It is thought that circulating immune complexes and cytokines exert an important influence on the progression of this syndrome. Treatment is applied to inhibit certain aspects of PUK pathogenesis.

Prednisolone induces apoptosis in corneal epithelial cells through the intrinsic pathway

Glucocorticoid eye drops are one of the most widely used medications in ophthalmology. However, little is known about the effects of glucocorticoids on corneal epithelial cells that are directly exposed to topically-administered glucocorticoids. Here we investigated the effects of prednisolone, a synthetic glucocorticoid analogue frequently used in the clinic, on corneal epithelial cells. Results showed that prednisolone decreased survival of corneal epithelial cells by inhibiting proliferation and inducing apoptosis in a dose-dependent manner. The levels of mitochondrial reactive oxygen species (mtROS), cleaved caspase-3, and -9 were increased by prednisolone. The effects of prednisolone on apoptosis and mtROS were blocked 1) by the glucocorticoid receptor (GR) antagonist RU-38486, 2) in cells with GR siRNA knockdown, and 3) by treatment with N-acetylcysteine. Transcript levels of pro-inflammatory cytokines were increased in corneal epithelial cells upon hyperosmolar stress, but repressed by prednisolone. In NOD.B10.H2^b mice, topical administration of 1% prednisolone increased apoptotic cells in the corneal epithelium. Together, data indicate that prednisolone induces apoptosis in corneal epithelial cells through GR and the intrinsic pathway involving mtROS, caspase-9, and -3. The pro-apoptotic effects of glucocorticoids along with their anti-inflammatory effects should be considered when glucocorticoid eye drops are used in patients with ocular surface disease.