Retinopathy of prematurity (ROP) remains the leading cause of blindness in premature infants owing to abnormal retinal blood vessels development,but molecular mechanisms are still not fully elucidated. Oxygen-induced retinopathy (OIR) mouse is the extensively used angiogenesis model for the study of ROP pathogenesis. In this study, we investigated five cell types that composed the microenvironment of retinal vessels in OIR mice by single-cell RNA sequencing (scRNA-seq) and revealed a complex and time-dependent regulation of vascular arrest and angiogenesis in the OIR microenvironment. Importantly, we also observe that Müller glia exhibit robust expression of CST3 (cysteine protease inhibitor cystatin C) during the early phase of hypoxic adaptation, leading to capillary morphogenesis in the hyaloid, disrupting physiological vascular patterning and contributing to OIR development. Altogether, our study reveals pivotal roles of the retinal microenvironment in both normal vascularization and ROP progression,suggesting that CST3 is a potential therapeutic target for ROP.
Retinitis pigmentosa (RP) leads to visual impairment by causing the death of photoreceptor cells. Mitochondrial calpain-1, an intracellular enzyme dependent on Ca2+ signaling, induces cell death in RP by cleaving and releasing apoptosis-inducing factors from the mitochondria. Previously, we developed Tat-μCL, a mitochondrial calpain-1 inhibitor that protects the retina from degeneration in a rat model of RP. Herein, we investigated its effect on a rabbit model of RP, which is more human-like than the rat model. We used a transgenic (Tg) rabbit harboring a P347L rhodopsin mutation and applied saline or Tat-μCL to each eye of the Tg rabbit using eye drops. Before and after 8 and 16 weeks of saline or Tat-μCL instillation, we performed electroretinography (ERG) and optical coherence tomography (OCT). After measurement in week 16, each eye was collected and histologically analyzed using hematoxylin and eosin (HE) staining and immunostaining for glial fibrillary acidic protein, ionized calcium-binding adapter molecule 1, apoptosis-inducing factor, and Tat-μCL. Tat-μCL substantially inhibited retinal thinning as determined via OCT and tended to improve the amplitude of the a- and b-waves in ERG measurement compared to saline. HE staining showed that Tat-μCL preserved the number of nuclear layers in the outer nuclear layer of the retina. Mitochondrial calpain-1 inhibition using Tat-μCL as eye drops prevented retinal degeneration in Tg rabbits, similar to our previous results from the rat model. These results validate our earlier findings that Tat-μCL preserves photoreceptor cells and delays disease progression in RP. Our findings need further validation in clinical settings.
Acanthamoeba keratitis (AK) is a severe infection caused by opportunistic protozoa called Acanthamoeba species, especially in contact lens wearers and immunocompromised people. The aim of the study was to assess the therapeutic efficiency of two nitazoxanide (NTZ) formulations in treating experimentally induced AK. Seven groups of 31 male New Zealand white rabbits were formed: Group (A-s) was infected and administered NTZ in suspension form; Group (A-c): the control group of the previous; Group (B-s): infected and administered NTZ in liquid crystal forming system; Group (B-c): the control group of the previous; Group (C-s): infected and administered topical chlorhexidine 0.02%; Group (C-c): the control group of the previous and Group (D): a normal control group. The effects of treatment were assessed over 30 days through daily clinical evaluation, grading of AK, parasitological and histopathological examination of corneal tissues. The present work revealed that after inducing keratitis, signs of infection appeared by day 3, and all groups showed similar infection rates before treatment began. Corneal opacity improved significantly in NTZ liquid crystal form- treated group, especially by days 18 to 30, showing outcomes comparable or superior to the chlorhexidine-treated group and markedly better than the NTZ suspension- treated group. Histopathological analysis confirmed these findings, with the NTZ liquid crystal group exhibiting minimal inflammation and no detectable cysts, highlighting its potential as an effective alternative treatment for AK.

