Corneal Inflammatory Reaction Research Articles

NLRP3 Inflammasome-Mediated Pyroptosis Pathway Contributes to the Pathogenesis of Candida albicans Keratitis.

PurposeFungal keratitis is a sight-threatening corneal infection caused by fungal pathogens, and the pathogenic mechanisms have not been fully elucidated. The aim of this study was to determine whether NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis contributes to Candida albicans (C. albicans) keratitis and explore the underlying mechanism.MethodsAn in vivo mouse model of C. albicans keratitis and an in vitro culture model of human corneal epithelial cells (HCECs) challenged with heat-killed C. albicans (HKCA) were established in this study. The degree of corneal infection was evaluated by clinical scoring. Gene expression was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis or immunofluorescence staining was performed to evaluate protein expression. TdT-mediated dUTP nick end labeling (TUNEL) staining was performed to examine the pyroptotic cell death. A lactate dehydrogenase (LDH) release assay was performed to assess cytotoxicity.ResultsCompared with the mock-infected group, we observed that the mRNA levels of NLRP3, caspase-1 (CASP1), interleukin (IL)−1β and gasdermin-D (GSDMD) in C. albicans-infected mice cornea was significantly increased. Our data also demonstrated that the protein expression of NLRP3 and the pyroptosis-related markers apoptosis-associated speck-like protein containing a CARD (ASC), cleaved CASP1, N-GSDMD, cleaved IL-1β and cleaved IL-18 as well as pyroptotic cell death were dramatically elevated in the mouse model of C. albicans keratitis. More importantly, NLRP3 knockdown markedly alleviated pyroptosis and consequently reduced corneal inflammatory reaction in C. albicans keratitis. In vitro, the presence of activated NLRP3 inflammasome and pyroptotic cell death were validated in HCECs exposed to HKCA. Furthermore, the potassium (K+) channel inhibitor glyburide decreased LDH release and suppressed NLRP3 inflammasome activation and pyroptosis in HCECs exposed to HKCA.ConclusionIn conclusion, the current study revealed for the first time that NLRP3 inflammasome activation and pyroptosis occur in C. albicans-infected mouse corneas and HCECs. Moreover, NLRP3 inflammasome-mediated pyroptosis signaling is involved in the disease severity of C. albicans keratitis. Therefore, This NLRP3 inflammasome-dependent pathway may be an attractive target for the treatment of fungal keratitis.

Оценка состояния глазной поверхности у пациентов с отягощенным общесоматическим анамнезом. Ранняя диагностика, способы лечения и профилактики

Introduction. Modern computerisation, frequent use of contact correction, surgical interventions on the visual organ and long-term drug installations often lead to the formation and further progression of dry eye syndrome (DES) with subsequent increased sensitivity and inflammatory symptoms on the conjunctiva and cornea. Purpose. Evaluation of the condition of the eye surface in patients with a burdened general somatic history. Development of measures for prevention, diagnosis and comprehensive treatment of this condition. Material and methods. A retrospective analysis of disease histories and medical records of 108 patients (108 eyes) with phacoemulsification of uncomplicated cataract with IOL implantation was carried out. Patients were divided into three main groups based on the presence of burdening factors of somatic status and the course of the postoperative period: I group included patients with unburdened somatic status and no complications during the course of the postoperative period; II group included patients with burdened general somatic history with complications during the course of the postoperative period; 3rd group included patients with burdened general somatic history with complications during the course of the postoperative period. 3rd group of patients used a special scheme to prevent and treat inflammatory reactions from the eye surface. Results. 1st group patients were less likely to complain and had no clinical manifestations of conjunctival and corneal inflammatory responses. Accordingly, this group of patients did not require additional treatment, which is indicative of the low incidence of complications in this category of patients. II group patients who had been identified as predisposing factors for conjunctival and corneal inflammatory reactions and did not receive additional treatment were more likely to experience complaints and the frequency of clinical manifestations was 20% higher than III group patients. Patients in III group required additional treatment in the postoperative period. Conclusion. Prolonged prescription of high doses of drugs of different groups with different preservative and auxiliary substances content in patients after surgical intervention in some cases leads to damage to the conjunctival and corneal epithelium, which in turn causes an aggravation of symptoms of SSG with the development of inflammatory reaction of the conjunctiva and cornea. The application of preventive measures before and after the surgery leads to a significant reduction in the objective manifestations of the eye surface complications and, as a result, a reduction in the number of complaints from patients about discomfort in the postoperative period. Key words: ocular surface, dry eye syndrome, cataract, allergies, tear film stability.

Protective Effect of Vitamin C against Infancy Rat Corneal Injury Caused by Acute UVB Irradiation.

Purpose Studies have shown that corneas of young children were more susceptible to Ultraviolet B (UVB) radiation damage. However, there exist limited information about the harm of UVB to eyes and preventive measures on infancy. Vitamin C as an antioxidant is widely used to prevent many diseases. Therefore, the aim of this study was to explore the protective effect of vitamin C on the cornea of infant rats with acute UVB injury. Method Thirty-six infant rats were randomly divided into three groups: control (CON) group, UVB (UVB) group, and UVB+vitamin C (UVB+VitC) group. The UVB group was exposed to UVB irradiation (8 J/cm2, 15 min/d, 7 d) and the UVB+vitamin C group suffered the same UVB irradiation treated with vitamin C at the dose of 40 mg/kg via intraperitoneal injection. Then, corneal morphology was detected in vivo and in vitro at 7 d post-UVB exposure. Furthermore, serum inflammatory factors (IL-1, IL-6, and TNF-α) and oxidative status (4-HNE and MDA) were detected by ELISA, and the expression of vascular endothelial growth factor-α (VEGF-α) and superoxide dismutase (SOD) in the cornea was detected by western blot or immunofluorescent staining. Results Slit lamp detection revealed that the area of corneal desquamation and corneal neovascularization in the UVB+VitC group was significantly less than those in the UVB group at 7 d post-UVB exposure (all p < 0.05). OCT results showed that the thickness of the central cornea in the UVB+VitC group was decreased than that in the UVB group (p < 0.05). The serum inflammatory factors (IL-1, IL-6, and TNF-α) and oxidative status (4-HNE and MDA) in the UVB group were significantly increased compared with the CON group (all p < 0.05), while those factors in the UVB+VitC group were decreased compared with those in the UVB group. Furthermore, the expression of VEGF-α in the UVB+VitC group was dramatically decreased compared with that in the UVB group (p < 0.05), and the expression of SOD2 in the UVB+VitC group was dramatically increased compared with that in the UVB group at 7 d post-UVB exposure (p < 0.05). Conclusion Vitamin C could protect infant rats from corneal injury induced by UVB via alleviating corneal edema, improving corneal inflammatory reaction, and decreasing VEGF-α expression.

Observation on the efficacy of retinoic acid for alkali corneal burn in rats

Objective To observe the efficacy of retinoic acid (RA) for the treatment of rats with corneal alkali burn. Methods The corneal alkali burn model of 36 Sprague-Dawley rats was established, all cases were randomly divided into RA group and control group, with 18 cases in each. RA group received RA eye drops and the control group received lysozyme of RA eye drops. The corneal morphology changes, conjunctival goblet cell count and corneal neovascularization area were measured. The number of inflammatory cells and expression of inflammatory factor in the corneal line of rat were observed by HE staining and immunohistochemical staining. Results The corneal neovascular area and inflammatory cell count after corneal alkali burn in RA group were lower than those of the control group. The conjunctival goblet cells count were higher than those of the control group at 4 and 7 days after corneal alkali burn, the difference was not significant at 14 days after corneal alkali burn. The expression of IL-1α, NF-κB and VEGF in the RA group were lower than those in the control group at 4 and 7 days after corneal alkali burn. At 14 days after corneal alkali burn, the VEGF expression in the RA group was lower than that of the control group, but the difference in the expression of IL-1α and NF-κB were not significant between the two group (IL-1α: 1.84±0.15 and 2.01±0.19, t=-2.26, P=0.347; NF-κB: 1.83±0.35 and 2.00±0.33, t=-2.59, P=0.695). Conclusion RA can control corneal inflammatory reaction and neovascularization by inhibiting the expression of IL-1α, NF-κB and VEGF. RA is effective for the treatment of alkali corneal burn. Key words: Retinoic acid; Burn, alkali, corneal; Neovascularization

Visualization of Immune Responses in the Cornea.

The eye has become a useful site for the investigation and understanding of local and systemic immune responses. The ease of access and transparency of the cornea permits direct visualization of ocular structures, blood vessels, and lymphatic vessels, allowing for the tracking of normal and pathological biological processes in real time. As a window to the immune system, we have used the eye to dissect the mechanisms of corneal inflammatory reactions that include innate and adaptive immune responses. We have identified that the ocular microenvironment regulates these immune responses by recruiting different populations of inflammatory cells to the cornea through local production of selected chemokines. Moreover, crosstalk between T cells and macrophages is a common and crucial step in the development of ocular immune responses to corneal alloantigens. This review summarizes the data generated by our group using intravital fluorescent confocal microscopy to capture the tempo, magnitude, and function of innate and adaptive corneal immune responses.

Cauterization of Central Cornea Induces Recruitment of Major Histocompatibility Complex Class II+ Langerhans Cells From Limbal Basal Epithelium

The purpose of this study was to investigate the distribution and characterization of Langerhans cells (LCs) in the rat corneal epithelium and to compare the findings with those obtained earlier in the mouse corneal epithelium. Normal and cauterized corneal tissues were excised from Wistar rats, and immunofluorescence staining for major histocompatibility complex (MHC) class II, CD3, CD11c, CD11b, CD45, CD80(B-1), and CD86(B-2) was performed by confocal microscopy. The density of intraepithelial MHC class II+ LCs was quantified. In the normal corneal epithelium, CD11c+ cells were exclusively distributed in the limbal and peripheral areas. Double staining showed that these cells were CD45 and MHC class II positive and B7 (CD80 or CD86) costimulatory molecules, CD11b, and CD3 negative, exhibiting a dendritic cell phenotype. In cauterized cornea, the expression of MHC class II was significantly enhanced in the limbal basal epithelium. The expression of the activation markers, CD80 and CD86, by MHC class II+ LCs was first present in the limbal basal epithelium as early as 4 hours after corneal inflammation and later throughout the entire corneal epithelium. The present study demonstrates for the first time the distribution and characterization of LCs in the rat corneal epithelium, which largely resembles most of those observed in the mouse cornea. In the cauterized cornea, B7+ LCs were first present in the limbal basal epithelium, suggesting that these cells play an important role in corneal inflammatory reaction.

Recent studies on the distribution and immune characterization of dendritic cells in the corneal epithelium

Langerhans cell-type dendritic cells (DCs) present in the corneal epithelium are capable of taking up, processing, and presenting antigens, leading to the initiation of T-lymphocyte responses. These cells are the professional antigen-presenting cells (APCs) of the corneal epithelium and serves as the critical sentinel cells of the immune system in the ocular surface. A recent study has demonstrated that normal limbal basal epithelium is in fact endowed with a small number of slow-cycling DCs with expression of a limbal stem cell marker, ABCG2. Furthermore, it has been found that central corneal inflammation induces recruitment of major histocompatibility complex (MHC) class II(+) DCs from limbal basal epithelium. These findings suggest that limbal basal epithelial DCs play an important role in corneal inflammatory reaction.

Anti‐inflammatory effects of topical supernatant from human amniotic membrane cell culture on canine deep corneal ulcer after human amniotic membrane transplantation

The objective of this study was to examine the effect of topically applied human amniotic epithelial cell (HAEC) culture supernatant on corneal inflammatory reaction in dogs. Twenty-five dogs were randomly assigned into five groups. The control group consisted of five dogs with normal cornea. Inductions of corneal ulcers were performed using 0.45 cm trephine and human amniotic membrane was transplanted in 20 dogs. These 20 dogs were assigned into four treatment groups: topical antibiotic, topical corticosteroid, topical mock media and topical culture supernatant from HAEC, respectively. Administrations of the testing agents started at 24 h (h) after transplantation four times daily for nine consecutive days. Tears were collected before an operation 24 h after transplantation, but before application of the testing agents on consecutive odd days following transplantation. The concentrations of interleukin-1beta (IL-1beta) and nitric oxide (NO) in tear fluid were measured using canine IL-1beta ELISA kit and Griess assay, respectively. Our analysis indicates that elevations of IL-1beta and NO concentrations are associated with inflammatory conditions in the eyes. Corticosteroid, a reference anti-inflammatory drug, and the culture supernatant from HAEC significantly decreased IL-1beta and NO concentrations. In addition, the clinical signs such as conjunctivitis and neovascularization were decreased in both topical corticosteroid and supernatant from HAEC treated groups. Mock and antibiotic solutions failed to decrease NO and IL-1beta concentrations. In conclusion, topical application of the culture supernatant from HAEC alleviated inflammation in induced-corneal ulcer of dogs, possibly via inhibition of IL-1beta and NO production.

Confocal Microscopic Evidence of Increased Langerhans Cell Activity after Corneal Metal Foreign Body Removal

The purpose of the study was to examine the corneal inflammatory reaction and Langerhans cells with confocal microscopy after metal foreign body removal. Corneal metal foreign body was removed from 9 eyes of 9 consecutive patients 12.1+/-13.6 (4 to 72) hours after superficial angle grinder injury. Both eyes were examined with the Heidelberg Retina Tomograph II (HRT II) Rostock Cornea Module. Morphology and density of epithelium, nerves, metal deposits, keratocytes, endothelium, and Langerhans cells were compared to the uninjured fellow eyes (controls). Irregularity and partially missing superficial epithelium was found in all cases. Around the area of injury prolonged basal and wing epithelial cells were found in all eyes. The basal epithelium density is lower than in the control eye (p=0.043). Density of Langerhans cells (68.1+/-24.2/mm2) was increased in the epithelium, compared to controls (35.2+/-21.8/mm2, p=0.012). Keratocyte and endothelium densities were not different from that of controls. Some keratocytes showed signs of activation and the inhomogeneous background reflectivity revealed extracellular matrix alterations. Inflammatory reaction was observed up to260 micronm depth. The metal foreign body particles had high reflectivity and irregular edge. In vivo confocal microscopy provided additional information to biomicroscopic signs such as epithelial damage and inflammation. It showed the effects of metal foreign bodies in the cornea: nerve damage and Langerhans cell density increase. Langerhans cells seem to play an important role in the inflammatory response after corneal foreign body injuries.

Thymosin β‐4 and the Eye

The cornea epithelium responds to injury by synthesizing several cytokines, growth factors, and tissue remodeling molecules. Proinflammatory cytokines have been implicated in the inflammation that follows corneal epithelial injury and cytokine-mediated processes play a significant role in corneal epithelial wound healing. Poorly regulated corneal inflammatory reactions that occur after injury can retard healing. In turn, persistent corneal epithelial defects and inflammation may lead to ocular morbidity and permanent visual loss. Therefore, treatments with agents that enhance corneal reepithelialization and regulate the inflammatory response without the deleterious side effects of currently used agents, such as corticosteroids, would result in improved clinical outcome and would represent a major advance in the field. Evidence is mounting to support the idea that thymosin beta-4 (Tbeta-4) has multiple, seemingly diverse, cellular functions. In the cornea, as in other tissues, Tbeta-4 promotes cell migration and wound healing, has anti-inflammatory properties, and suppresses apoptosis. Prior studies from our laboratory have demonstrated the potent wound healing and anti-inflammatory effects of Tbeta-4 in numerous models of corneal injury. Recently, we demonstrated that Tbeta-4 suppresses the activation of the transcription factor, nuclear factor-kappa b (NF-kappaB) in TNF-alpha-stimulated cells. TNF-alpha initiates cell signaling pathways that converge on the activation of NF-kappaB, thus both are known mediators of the inflammatory process. These results have important clinical implications for the potential role of Tbeta-4 as a corneal anti-inflammatory and wound-healing agent.

Topical application of culture supernatant from human amniotic epithelial cells suppresses inflammatory reactions in cornea

Human amniotic epithelial cells (HAEC) may be a source of soluble anti-inflammatory factors. The purpose of this study is to determine the effect of topically applied HAEC culture supernatant on corneal inflammatory reactions. HAEC were obtained from a placenta and cultured for 48 hr, and the supernatant was collected. The conditioned medium from HAEC contained small amounts of human interleukin-1 receptor antagonist (IL-1ra). Intrastromal sutures were placed in the cornea of BALB/c mice to induce corneal neovascularisation. Superficial cauterisation was applied to induce recruitment or activation of antigen presenting cells (APCs) in the cornea without neovascularisation. HAEC conditioned medium, placebo, or recombinant human IL-1ra was topically applied three times daily for 2 weeks. Suture-induced corneal neovascularisation was evaluated microscopically for 8 weeks. The cauterised corneas were harvested at 2 weeks, and the MHC class II + APCs were quantified by immunofluorescent staining and confocal microscopy. Inflammatory cytokine gene expression in the cauterised corneas was analyzed by a multiprobe ribonuclease protection assay. Conditioned medium from HAEC led to a profound suppression of corneal neovascularisation and fewer MHC class II + APCs in the epithelium. In contrast, human IL-1ra was only slightly effective in suppressing corneal inflammatory reactions. mRNA expression of murine IL-1ra and IL-1beta in the cauterised corneas was markedly suppressed after application of the conditioned medium. These results suggest that HAEC are a source of soluble anti-inflammatory factors and that conditioned medium from HAEC contains factors other than IL-1ra that suppress corneal inflammation.

Expression of adhesion molecule CD44 on human corneas

AIMSThis study was undertaken to confirm the distribution and expression of the molecule CD44 on human corneas under normal and pathological conditions.METHODSFifty eight corneal buttons from adult patients suffering from...

Ocular immunopathologic findings of experimental onchocerciasis.

Ocular immunopathologic responses of inbred guinea pigs infected with Onchocerca microfilariae from domesticated animals were studied as a laboratory model of human ocular onchocerciasis. A single intracorneal infection of normal guinea pigs with microfilariae produced only minimal ocular lesions. In contrast, intracorneal infection of guinea pigs previously immunized by systemic infection with microfilariae produced intense corneal and uveal inflammation. Transfer of splenic lymphocytes from immunized donors to syngeneic normal recipients substituted effectively for the active immunization. Cell recipients produced marked corneal inflammatory reactions when challenged by a single intracorneal infection. Fresh and cryopreserved microfilariae produced identical reactions. The corneal inflammatory infiltrates were composed primarily of eosinophils, neutrophils, and plasma cells and resembled human onchocercal keratitis. Diethylcarbamazine citrate administration after a challenge intracorneal infection increased the severity of the corneal inflammatory response in immunized animals.