Ocular microbiota promotes pathological angiogenesis and inflammation in sterile injury-driven corneal neovascularization

Pharmacomicrobiomics in precision cancer therapy: bench to bedside

The burgeoning field of pharmacomicrobiomics offers promising insights into the intricate interplay between the microbiome and cancer, shaping responses to diverse treatment modalities. This review aims to analyze the molecular mechanisms underlying interactions between distinct microbiota types and cancer, as well as their influence on treatment outcomes. We explore how the microbiome impacts antitumor immunity, and response to chemotherapy, immunotherapy, and radiation therapy, unveiling its multifaceted roles in cancer progression and therapy resistance. Moreover, we discuss the challenges hindering the development of microbiome-based interventions in cancer therapy, including standardization, validation, and clinical translation. By synthesizing clinical evidence, we underscore the transformative potential of harnessing pharmacomicrobiomics in guiding cancer treatment decisions, paving the way for improved patient outcomes in clinical practice.

Autophagy-mediated activation of the AIM2 inflammasome enhances M1 polarization of microglia and exacerbates retinal neovascularization

Retinopathy of prematurity (ROP) is a retinal neovascularization (RNV) disease that is characterized by abnormal blood vessel development in the retina. Importantly, the etiology of ROP remains understudied. We re-analyzed previously published single-cell data and discovered a strong correlation between microglia and RNV diseases, particularly ROP. Subsequently, we found that reactive oxygen species reduced autophagy-dependent protein degradation of absent in melanoma 2 (AIM2) in hypoxic BV2 cells, leading to increased AIM2 protein accumulation. Furthermore, we engineered AIM2 knockout mice and observed that the RNV was significantly reduced compared to wild-type mice. In vitro vascular function assays also demonstrated diminished angiogenic capabilities following AIM2 knockdown in hypoxic BV2 cells. Mechanistically, AIM2 enhanced the M1-type polarization of microglia via the ASC/CASP1/IL-1β pathway, resulting in RNV. Notably, the administration of recombinant protein IL-1β exacerbated angiogenesis, while its inhibition ameliorated the condition. Taken together, our study provides a novel therapeutic target for ROP and offers insight into the interaction between pyroptosis and autophagy.

Subconjunctival aflibercept inhibits corneal angiogenesis and VEGFR-3+CD11b+ cells

PURPOSE

This study aimed to investigate the effects of subconjunctival injection of aflibercept, a soluble protein decoy for VEGFR-1 and VEGFR-2, on corneal angiogenesis and VEGFR-expressing CD11b+ cells in a mouse model of suture-induced corneal neovascularization.

METHODS

Corneal neovascularization was induced in BALB/c mice by placing three sutures on the cornea. Immediately after surgery, either 200 µg aflibercept (5 µL) or an equal volume of phosphate-buffered saline (PBS) was administered into the subconjunctival space. Seven days after later, corneal new vessels were quantified through clinical examination and measurement of the CD31-stained area in corneal flat mounts. The levels of pro-angiogenic and inflammatory markers in the cornea were evaluated using RT-qPCR. The percentages of VEGFR-2+CD11b+ cells and VEGFR-3+CD11b+ cells were analyzed in the cornea, blood, and draining cervical lymph nodes (DLNs) using flow cytometry.

RESULTS

Subconjunctival injection of aflibercept significantly reduced the growth of corneal new vessels compared to subconjunctival PBS injection. The mRNA levels of Cd31, vascular growth factors (Vegfc and Angpt1), and pro-angiogenic/inflammatory markers (Tek/Tie2, Mrc1, Mrc2, and Il6) in the cornea were downregulated by subconjunctival aflibercept. Also, the percentage of VEGFR-3+CD11b+ cells in the cornea, blood, and DLNs was decreased by aflibercept, whereas that of VEGFR-2+CD11b+ cells was unaffected.

CONCLUSION

Subconjunctival aflibercept administration inhibits inflammatory angiogenesis in the cornea and reduces the numbers of cornea-infiltrating and circulating VEGFR-3+CD11b+ cells.

Restoration of corneal epithelial barrier function: A possible target for corneal neovascularization

Corneal neovascularization (CoNV) is the second leading common cause of vision impairment worldwide and is a blinding pathological alteration brought on by ocular trauma, infection, and other factors. There are some limitations in the treatment of CoNV, hence it's critical to look into novel therapeutic targets. The corneal epithelial barrier, which is the initial barrier of the ocular surface, is an important structure that shields the eye from changes in the internal environment or invasion by the external environment. This study sought to collate evidence on the regulation of corneal epithelial barrier injury on the activation of vascular endothelial cells (VECs), basement membrane (BM) degradation, differentiation, migration, and proliferation of VECs, vascular maturation and stability, and other key processes in CoNV, so as to provide a novel concept for CoNV therapy targeting corneal epithelial barrier repair.

Ozone exposure affects corneal epithelial fate by promoting mtDNA leakage and cGAS/STING activation

Ozone is a common air pollutant associated with various human diseases. The human ocular surface is frequently exposed to ozone in the troposphere, but the mechanisms by which ozone affects the ocular surface health remain unclear. This study aimed to establish a mouse model to investigate the effects of ozone exposure on the ocular surface and the corneal epithelium. The findings revealed that ozone exposure disrupted corneal epithelial homeostasis and differentiation, resulting in corneal squamous metaplasia. Further, ozone exposure induced oxidative damage and cytoplasmic leakage of mitochondrial DNA (mtDNA), thereby activating the cGAS/STING signaling pathway. The activation of the cGAS/STING signaling pathway triggered the activation of downstream NF-κB and TRAF6 signaling pathways, causing corneal inflammation, thereby promoting corneal inflammation and squamous metaplasia. Finally, C-176, a selective STING inhibitor, effectively prevented and treated corneal inflammation and squamous metaplasia caused by ozone exposure. This study revealed the role of mtDNA leakage-mediated cGAS/STING activation in corneal squamous epithelial metaplasia caused by ozone exposure. It also depicted the abnormal expression pattern of corneal epithelial keratin using three-dimensional images, providing new targets and strategies for preventing and treating corneal squamous metaplasia and other ocular surface diseases.

Ocular mucosal homeostasis of teleost fish provides insight into the coevolution between microbiome and mucosal immunity

BACKGROUND

The visual organ plays a crucial role in sensing environmental information. However, its mucosal surfaces are constantly exposed to selective pressures from aquatic or airborne pathogens and microbial communities. Although few studies have characterized the conjunctival-associated lymphoid tissue (CALT) in the ocular mucosa (OM) of birds and mammals, little is known regarding the evolutionary origins and functions of immune defense and microbiota homeostasis of the OM in the early vertebrates.

RESULTS

Our study characterized the structure of the OM microbial ecosystem in rainbow trout (Oncorhynchus mykiss) and confirmed for the first time the presence of a diffuse mucosal-associated lymphoid tissue (MALT) in fish OM. Moreover, the microbial communities residing on the ocular mucosal surface contribute to shaping its immune environment. Interestingly, following IHNV infection, we observed robust immune responses, significant tissue damage, and microbial dysbiosis in the trout OM, particularly in the fornix conjunctiva (FC), which is characterized by the increase of pathobionts and a reduction of beneficial taxa in the relative abundance in OM. Critically, we identified a significant correlation between viral-induced immune responses and microbiome homeostasis in the OM, underscoring its key role in mucosal immunity and microbiota homeostasis.

CONCLUSIONS

Our findings suggest that immune defense and microbiota homeostasis in OM occurred concurrently in early vertebrate species, shedding light on the coevolution between microbiota and mucosal immunity. Video Abstract.

Temporal dynamics and composition of ocular surface microbiota in C57BL/6J mice: uncovering a 12h ultradian rhythm

Purpose

This study aimed to investigate the presence of rhythmic fluctuations in the composition, abundance, and functions of commensal core bacteria on the ocular surface of C57BL/6J mice.

Methods

Male C57BL/6J mice, aged 12 weeks, were subjected to a 12-hour light/12-hour dark cycle. Ocular surface tissue samples were collected at four time points (ZT) over a 24-hour period at six-hour intervals. The core ocular surface microbiota's oscillation cycles and frequencies were assessed using 16S rRNA gene sequencing targeting the V3-V4 region, along with the JTK_CYCLE algorithm. Functional predictions of these bacteria were conducted using PICRUSt2.

Results

Deep sequencing of the ocular surface microbiota highlighted the high abundance of commensal bacteria, with Proteobacteria, Actinobacteriota, and Firmicutes collectively constituting over 90% of the total sample abundance. Among the 22 core bacterial genera, 11 exhibited robust 12-hour rhythms, including Halomonas, Pelagibacterium, Pseudomonas, Nesterenkonia, norank_f_Hyphomonadaceae, Stenotrophomonas, Anoxybacillus, Acinetobacter, Zoogloea, Brevibacillus, and Ralstonia. Further taxonomic analysis indicated significant intra-cluster similarities and inter-cluster differences at the order, family, and genus levels during ZT0/12 and ZT6/18. Community interaction networks and functional prediction analyses revealed synchronized 12-hour rhythmic oscillations in neural, immune, metabolic, and other pathways associated with symbiotic bacteria.

Conclusion

This study demonstrates the presence of ultradian rhythmic oscillations in commensal bacteria on the ocular surface of normal C57BL/6J mice, with a 12-hour cycle. These findings suggest a crucial role for ultradian rhythms in maintaining ocular surface homeostasis in the host.