Clinical Features, Antibiotic Susceptibilities, and Outcomes of Endophthalmitis Caused by Streptococcal Infection: Children vs. Adults.

Streptococcus spp. are common causative organisms of endophthalmitis. Analysis of the clinical features, antibiotic susceptibilities, and outcomes of streptococcal endophthalmitis in children and adults may guide future management. Sixty-seven patients (67 eyes) with streptococcal endophthalmitis who were admitted to the Zhongshan Ophthalmic Center between January 2013 and December 2022 were retrospectively reviewed. The mean age was 20.7 ± 21.6 years, and 59.7% were children. Streptococcal infection accounted for 13.9% of culture-proven bacterial endophthalmitis cases; the proportion was higher in children than in adults (32.3% vs. 7.6%, p < 0.01) and increased from 8.1% in 2013-2017 to 20.1% in 2018-2022 (p < 0.01). Eye trauma was the most common etiology in both children and adults (82.5% and 66.7%, respectively). Viridans group streptococci were the most common isolates, followed by S. pneumoniae. The susceptibility rates of the streptococci to vancomycin, cefuroxime, and levofloxacin were 100%, 95.5%, and 93.0%, respectively. The overall mean best-corrected visual acuity increased from 2.74 ± 0.19 logMAR initially to 2.32 ± 0.75 logMAR at the last follow-up (p < 0.05). In conclusion, streptococcal infections have increased in cases of bacterial endophthalmitis in recent years and are more common in children. The commonly used antibiotics, vancomycin, cefuroxime, and fluoroquinolone, showed higher antibiotic susceptibility. After prompt treatment, visual outcomes improved.

Intravitreal slow-release dexamethasone alleviates traumatic proliferative vitreoretinopathy by inhibiting persistent inflammation and Müller cell gliosis in rabbits.

AIM: To evaluate the effects of intravitreal slow-release dexamethasone on traumatic proliferative vitreoretinopathy (PVR) and Müller cell gliosis and preliminarily explored the possible inflammatory mechanism in a rabbit model induced by penetrating ocular trauma. METHODS: Traumatic PVR was induced in the right eyes of pigmented rabbits by performing an 8-mm circumferential scleral incision placed 2.5 mm behind the limbus, followed by treatment with a slow-release dexamethasone implant (Ozurdex) or sham injection. Left eyes were used as normal controls. The intraocular pressure (IOP) was monitored using an iCare tonometer. PVR severity was evaluated via anatomical and histopathological examinations every week for 6wk; specific inflammatory cytokine and proliferative marker levels were measured by quantitative real-time polymerase chain reaction, Western blot, protein chip analysis, or immunofluorescence staining. RESULTS: During the observation period, PVR severity gradually increased. Intense Müller cell gliosis was observed in the peripheral retina near the wound and in the whole retina of PVR group. Ozurdex significantly alleviated PVR development and Müller cell gliosis. Post-traumatic inflammation fluctuated and was persistent. The interleukin-1ß (IL-1ß) mRNA level was significantly upregulated, peaking on day 3 and increasing again on day 21 after injury. The expression of nod-like receptor family pyrin domain containing 3 (NLRP3) showed a similar trend that began earlier than that of IL-1ß expression. Ozurdex suppressed the expression of IL-1ß, NLRP3, and phosphorylated nuclear factor-kappa B (NF-κB). The average IOP after treatment was within normal limits. CONCLUSION: The present study demonstrates chronic and fluctuating inflammation in a traumatic PVR rabbit model over 6wk. Ozurdex treatment significantly inhibites inflammatory cytokines expression and Müller cell gliosis, and thus alleviates PVR severity. This study highlights the important role of IL-1ß, and Ozurdex inhibites inflammation presumably via the NF-κB/NLRP3/IL-1ß inflammatory axis. In summary, Ozurdex provides a potential therapeutic option for traumatic PVR.

Comparative Study of Ocular Pharmacokinetics of Topical 0.3% Gatifloxacin Eye Gel and Solution in Rabbits.

Few articles have reported drug concentrations of different ophthalmic dosage forms in the ocular tissues. This study aimed to determine the ocular pharmacokinetics of gatifloxacin 0.3% eye gel (GTX-Gel) and gatifloxacin 0.3% eye solution (GTX-Sol) at different time intervals after topical instillation in rabbits. A total of 126 healthy New Zealand rabbits were included, of which six rabbits did not receive antibiotics (control group). The remaining rabbits were randomly divided into four groups. GTX-Gel and GTX-Sol (50 µL) were topically instilled every hour in groups A1 and B1, respectively, and every two hours in groups A2 and B2, respectively, for 12 h. Ocular tissues were collected 2, 4, 8, 12, and 24 h after administration. Gatifloxacin concentration was measured using high-performance liquid chromatography coupled with tandem mass spectrometry. The drug reached peak concentrations (Cmax) in all tissues at 8−12 h. With the same administration frequency, the Cmax was higher with GTX-Gel than with GTX-Sol (p < 0.05). Except for the iris-ciliary body, other ocular tissues did not show significant difference (p > 0.05) in gatifloxacin concentration between either pair of groups. Gatifloxacin ophthalmic gel was found to attain significantly higher concentrations than the ophthalmic solution in ocular tissues.

Post-traumatic endophthalmitis caused by streptococcus species in preschool children: clinical features, antibiotic susceptibilities and outcomes.

BACKGROUND/OBJECTIVES: Streptococcus is a common cause of post-traumatic endophthalmitis in children. This study aimed to analyse the clinical features, antibiotic susceptibilities and outcomes of traumatic endophthalmitis caused by streptococcus in preschool children. SUBJECTS/METHODS: Patients aged ≤6 years with traumatic streptococcal endophthalmitis seen at Zhongshan Ophthalmic Center between January 2013 and December 2018 were included in this retrospective study. RESULTS: In total, 21 patients (21 eyes) were included. The mean age of the patients was 3.3 ± 1.7 years, where 57.1% were males. Scissors (28.6%, n = 6) were the most common cause of injury; 86.7% of patients were injured at home. Zone I (80.9%) was the most common wound site; 90.5% of patients presented with a traumatic cataract. In general, Streptococcus pneumoniae (47.6%) was the most common isolate. Viridans group streptococci accounted for 58.3% of cases in children aged 0-3 years, while S. pneumoniae accounted for 66.7% of cases in children aged 4-6 years. The susceptibility rates of streptococcus to cefuroxime, levofloxacin and ofloxacin were 100%, 95.0% and 90.5%, respectively. Although all the patients underwent vitrectomy combined with silicone oil tamponade, the final visual outcomes were no better than counting fingers. CONCLUSIONS: Although S. pneumoniae was the most prevalent organism in general, the dominant species varied between different age groups. The commonly used antibiotics, cefuroxime and fluoroquinolone, showed higher antibiotic susceptibility. Despite prompt treatment, the visual outcomes of paediatric post-traumatic endophthalmitis in preschool children were poor.

METTL3 attenuates proliferative vitreoretinopathy and epithelial-mesenchymal transition of retinal pigment epithelial cells via wnt/ß-catenin pathway.

Proliferative vitreoretinopathy (PVR) is a refractory vitreoretinal fibrosis disease, and epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is the key pathological mechanism of PVR. However, few studies focused on the role of METTL3, the dominating methyltransferase for m6A RNA modification in PVR pathogenesis. Immunofluorescence staining and qRT-PCR were used to determine the expression of METTL3 in human tissues. Lentiviral transfection was used to stably overexpress and knockdown METTL3 in ARPE-19 cells. MTT assay was employed to study the effects of METTL3 on cell proliferation. The impact of METTL3 on the EMT of ARPE-19 cells was assessed by migratory assay, morphological observation and expression of EMT markers. Intravitreal injection of cells overexpressing METTL3 was used to assess the impact of METTL3 on the establishment of the PVR model. We found that METTL3 expression was less in human PVR membranes than in the normal RPE layers. In ARPE-19 cells, total m6A abundance and the METTL3 expression were down-regulated after EMT. Additionally, METTL3 overexpression inhibited cell proliferation through inducing cell cycle arrest at G0/G1 phase. Furthermore, METTL3 overexpression weakened the capacity of TGFß1 to trigger EMT by regulating wnt/ß -catenin pathway. Oppositely, knockdown of METTL3 facilitated proliferation and EMT of ARPE-19 cells. In vivo, intravitreal injection of METTL3-overexpressing cells delayed the development of PVR compared with injection of control cells. In summary, this study suggested that METTL3 is involved in the PVR process, and METTL3 overexpression inhibits the EMT of ARPE-19 cells in vitro and suppresses the PVR process in vivo.

Risk Factors and Prognosis of Pediatric Open Globe Injuries without Initial Light Perception.

PURPOSE: The aim of this study was to investigate the possible risk factors and prognosis of initial no light perception (NLP) in pediatric open globe injuries (POGI). PROCEDURES: This retrospective, comparative, interventional case-control study included 865 eyes of POGI patients presenting to a tertiary referral ophthalmic center from January 1, 2011 to December 31, 2015. Eyes were divided into 2 groups: the NLP group included eyes with initial NLP, and the light perception (LP) group included eyes with initial LP or vision better than LP. RESULTS: The following risk factors were significantly related to initial NLP: severe intraocular hemorrhage (OR 3.287, p = 0.015), retinal detachment (RD; OR 2.527, p = 0.007), choroidal damage (OR 2.680, p = 0.016), and endophthalmitis (OR 4.221, p < 0.001). Choroidal damage is related to remaining NLP after vitreoretinal surgery (OR 12.384, p = 0.003). At the last visit, more eyes in the NLP group suffered from silicone oil-sustained status (OR 0.266, p = 0.020) or ocular atrophy (OR 0.640, p = 0.004), and fewer eyes benefitted from final LP (OR 41.061, p < 0.001) and anatomic success (OR 4.515, p < 0.001). CONCLUSION: Severe intraocular hemorrhage, RD, choroidal damage, and endophthalmitis were possible predictors of initial NLP in POGI. Choroidal damage was the major factor related to an NLP prognosis. Traumatized eyes with initial NLP could be anatomically and functionally preserved by vitreoretinal surgery.

Development of a rabbit model of persistent hypotony without ciliary body injury.

In order to study the pathophysiological alterations of the ciliary body (CB) during persistent hypotony, it is necessary to develop an animal model without CB injury. In this study, we successfully established a modified model of persistent hypotony without CB injury in New Zealand rabbits. A 23-gauge pars plana vitrectomy (PPV) was performed and a trocar-formed fistula was allowed to remain in situ, to produce a continuous outflow of intraocular fluid. Both eyes underwent PPV with normal intraocular pressure (IOP); eyes with no surgical intervention were used as controls. The IOP was monitored and used to evaluate the reliability of the model. Secondary changes of hypotony were evaluated by slit-lamp biomicroscopy and B scans while morphological changes of the CB were observed by haematoxylin and eosin staining. The mean IOP in the hypotony groups were consistently lower than 6 mmHg. Furthermore, there were no significant differences in IOP between the PPV control group and normal eyes. Collectively, our data indicate that this model successfully simulates the secondary changes of hypotony, including a reduction in corneal size, corneal oedema, anterior chamber inflammation, morphological alterations of the CB, cataract, retinal detachment, and choroidal detachment. The morphological structure of the CB tissue changed dramatically after persistent hypotony, indicating that normal IOP may be required in order to maintain normal function in the CB. This model of persistent hypotony potentially represents a valuable tool for future studies aiming to investigate the pathophysiological mechanisms underlying CB dysfunction and other secondary changes that occur during hypotony.

Artesunate induces mitochondria-mediated apoptosis of human retinoblastoma cells by upregulating Kruppel-like factor 6.

Retinoblastoma (RB) is the most common primary intraocular malignancy in children. Intravitreal chemotherapy achieves favorable clinical outcomes in controlling RB vitreous seeds, which are a common reason for treatment failure. Thus, a novel, effective and safe intravitreal chemotherapeutic drug is urgently required. The malaria drug artesunate (ART) recently demonstrated remarkable anticancer effects with mild side effects. The purpose of this study is to investigate the anti-RB efficacy, the underlying mechanism and the intraocular safety of ART. Herein, we verified that ART inhibits RB cell viability and induces cell apoptosis in a dose- and time-dependent manner. Microarray analysis revealed that Kruppel-like factor 6 (KLF6) was upregulated after ART treatment, and this was further confirmed by real-time PCR and western blot assays. Silencing of KLF6 expression significantly reversed ART-induced RB cell growth inhibition and apoptosis. Furthermore, ART activated mitochondria-mediated apoptosis of RB cells, while silencing KLF6 expression significantly inhibited this effect. In murine xenotransplantation models of RB, we further confirmed that ART inhibits RB tumor growth, induces tumor cell apoptosis and upregulates KLF6 expression. In addition, KLF6 silencing attenuates ART-mediated inhibition of tumor growth in vivo. Furthermore, we proved that intravitreal injection of ART in Sprague-Dawley (SD) rats is safe, with no obvious retinal function damage or structural disorders observed by electrophysiology (ERG), fundal photographs, fundus fluorescein angiography (FFA) or optical coherence tomography (OCT) examinations. Collectively, our study revealed that ART induces mitochondrial apoptosis of RB cells via upregulating KLF6, and our results may extend the application of ART to the clinic as an effective and safe intravitreal chemotherapeutic drug to treat RB, especially RB with vitreous seeds.

Effect of vitrectomy with intrasurgical regulation of intraocular pressure in a rabbit model of central retinal artery occlusion.

Central retinal artery occlusion (CRAO) is an ophthalmic emergency that causes severe and permanent visual impairment. The effects of conventional treatments on recanalizing retinal arteries and improving visual outcome are equivocal. This study was designed to determine the possible benefits of pars plana vitrectomy (PPV) with intrasurgical regulation of intraocular pressure using intraocular vascular counterpulsation (IVT). CRAO was induced by 532-nm argon green laser activation of auricular intravenous injected rose bengal, a photosensitive dye, in the central retinal arteries (CRA) of eighty-four New Zealand white albino rabbits. CRAO rabbits were randomly assigned to photocoagulation, vitrectomy and counterpulsation groups. Depending on the time intervals between surgery and CRAO induction, vitrectomy and counterpulsation groups were further divided into 2 h (2h), 6 h (6h) and 24 h (24h) subgroups. The proportion of eyes with complete recanalization was significantly higher in the 2h counterpulsation subgroup after three days (P = 0.032) and in all counterpulsation subgroups after one week (P = 0.020). After one month, the 2h and 6h counterpulsation subgroups showed greater oscillatory potential (OPs) responses (F = 3.519, P = 0.049). The 2h counterpulsation subgroup also exhibited greater b-wave amplitude in photopic 3.0 Flicker(F = 4.530, P = 0.044). Histologic evaluation revealed less destruction in the inner retina for the 2h and 6h counterpulsation subgroups. Expression of HSP70 was higher in the 2h and 6h counterpulsation subgroups (F = 48.915,P < 0.001). Levels of HSP90 were lower in all counterpulsation subgroups (F = 30.065,P < 0.001). Levels of TNF-α were lower in the 2h counterpulsation subgroup (F = 14.762,P < 0.001). These results indicate that PPV with IVT was effective to recanalize retinal arteries after CRAO. Early intervention provided better morphologic and functional prognosis for inner retina. The protective effect was related with higher retinal levels of HSP70 and lower levels of HSP90 and TNF-α.

Inhibition of Notch1 Signaling Alleviates Endotoxin-Induced Inflammation Through Modulating Retinal Microglia Polarization.

Microglial cells are resident immune cells and play an important role in various cerebral and retinal inflammatory diseases. Notch1 signaling is involved in the microglia polarization and the control of cerebral inflammatory reactions. However, its role in endotoxin-induced uveitis (EIU) remains unknown. This study aimed to investigate the role of Notch1 signaling on retinal microglia polarization and inflammation in the cultured retinal microglial cells and EIU rat model. We found that Notch1 signaling blockade with N-[N-(3, 5-difluorophenacetyl)-1-alany1-S-phenyglycine t-butyl ester (DAPT) shifted retinal microglia phenotype from pro-inflammatory M1 phenotype (COX2+ and iNOS+) to anti-inflammatory M2 phenotype (Arg-1+) and reduced the release of pro-inflammatory cytokines both in vivo and in vitro. Moreover, DAPT treatment contributed to prevent retinal ganglion cells from apoptosis, reduce the intraocular infiltrating cells, and attenuate the impairment of retinal function. Taken together, these results suggest that inhibition of Notch1 signaling could alleviate the inflammatory response in EIU rat mainly through regulating the polarization of retinal microglia. Therefore, Notch1 signaling might be a promising therapeutic target in the treatment of ocular inflammatory diseases.

Activation of cannabinoid receptor type 2 reduces lung ischemia reperfusion injury through PI3K/Akt pathway.

Cannabinoid receptor-2 activation plays a protective role against ischemic reperfusion injury (IRI) in various organs, and exerts a protective effect against paraquat-induced acute lung injury, while the role of CB2 in lung IRI remains unclear. Hence, the present study was designed to explore the role of CB2 in lung IRI, and whether the PI3K pathway was involved. C57BL/6 mice were subjected to lung ischemia by clamping the left hilum for 1 hour, followed by 2 hours' reperfusion. Mice were pretreated with vehicle, CB2 agonist JWH133, or antagonist AM630 followed by JWH133. Arterial blood and left lung tissues were collected to detect the PaO2/FiO2 ratio, lung wet-to-dry weight ratio, lung pathologic scoring, pro-inflammatory cytokines, MDA, and SOD. Secondly, mice were pretreated with vehicle, JWH133, or both PI3K-inhibitor LY294002 and JWH133. Arterial blood and left lung tissues were collected for the above studies and protein expression of CB2 receptor, p-AKT, and AKT. After mice were pretreated with JWH133, IR-induced lung edema and lung histopathologic changes were significantly attenuated. Pretreatment with JWH133 improved PaO2/FiO2 ratio, decreased lung TNF-α, IL-6, MDA levels and MPO activities, and increased SOD activity. By contrast, the protective effect of JWH133 was blocked by pretreatment with CB2 antagonist AM630. Similarly, pretreatment with PI3K-inhibitor weakened the protection induced by JWH133, and downregulated the expression of p-AKT without altering CB2 expression. The study suggested that activation of CB2 receptor plays a protective role against IR-induced lung injury through reducing inflammation in mice. The PI3K/Akt pathway might be involved in the protective effect of CB2 receptors in lung IRI.