Effect of the gut microbiome in glaucoma risk from the causal perspective

Evaluating the efficacy and safety of polyglycolic acid-loading mitomycin nanoparticles in inhibiting the scar proliferation after glaucoma filtering surgery

PURPOSE

To prepare a polyglycolic acid-loaded mitomycin drug (MMC-ATS-@PLGA) to inhibit scar proliferation after glaucoma filtering surgery (GFS) via an anti-inflammatory mechanism that minimally affected intraocular pressure, which provided another therapeutic strategy for this disease.

METHODS

We first detected the physicochemical properties of MMC-ATS-@PLGA. Next, we tested the biosafety of MMC-ATS-@PLGA in vivo and in vitro. Then, we assessed the therapeutic effects of MMC-ATS-@PLGA by laboratory and clinical examinations.

RESULTS

In this study, we synthesized a new type of nanomedicine (MMC-ATS-@PLGA) with good stability and biocompatibility for inhibiting scar proliferation after GFS. The break-up time (BUT), Schimer test and intraocular pressure changes in GFS rabbits before and after treatment with MMC-ATS-@PLGA were not significantly different. Three weeks after GFS, the MMC-ATS-@PLGA group displayed significant decreases in nuclear volume, corneal cell oedema, type I and III collagen fibre expression, normal organelle morphology and collagen fibre arrangement. Compared with those in the FML and MMC groups, the α-SMA, CTGF and type III collagen fibres in the MMC-ATS-@PLGA group decreased more significantly, indicating that MMC-ATS-@PLGA can effectively inhibit the expression of these inflammatory factors during the inhibition of scar proliferation after GFS.

CONCLUSION

We successfully synthesized MMC-ATS-@PLGA, which could effectively inhibit scar proliferation after GFS via anti-inflammatory effects but had little effect on intraocular pressure. This new type of nanomedicine has good biosafety and stability and is worthy of further exploration in clinical practice.

Association Between Glaucoma and Brain Structural Connectivity Based on Diffusion Tensor Tractography: A Bidirectional Mendelian Randomization Study

BACKGROUND

Glaucoma is a neurodegenerative ocular disease that is accompanied by cerebral damage extending beyond the visual system. Recent studies based on diffusion tensor tractography have suggested an association between glaucoma and brain structural connectivity but have not clarified causality.

METHODS

To explore the causal associations between glaucoma and brain structural connectivity, a bidirectional Mendelian randomization (MR) study was conducted involving glaucoma and 206 diffusion tensor tractography traits. Highly associated genetic variations were applied as instrumental variables and statistical data were sourced from the database of FinnGen and UK Biobank. The inverse-variance weighted method was applied to assess causal relationships. Additional sensitivity analyses were also performed.

RESULTS

Glaucoma was potentially causally associated with alterations in three brain structural connectivities (from the SN to the thalamus, from the DAN to the putamen, and within the LN network) in the forward MR analysis, whereas the inverse MR results identified thirteen brain structural connectivity traits with a potential causal relationship to the risk of glaucoma. Both forward and reverse MR analyses satisfied the sensitivity test with no significant horizontal pleiotropy or heterogeneity.

CONCLUSIONS

This study offered suggestive evidence for the potential causality between the risk of glaucoma and brain structural connectivity. Our findings also provided novel insights into the neurodegenerative mechanism of glaucoma.

The gut-eye axis: the retinal/ocular degenerative diseases and the emergent therapeutic strategies

The interplay between human microbiota and various physiological systems has garnered significant attention in recent years. The gut microbiota plays a critical role in maintaining physiological homeostasis and influences various aspects of human health, particularly via the gut brain axis. Since 2017, the challenging concept of the gut-retina axis has emerged thanks to a network analysis emphasizing the potential role of the gut microbiota disruption in the development of the age-related macular degeneration and further retinal damages. Many other ocular disorders have been linked to the dysbiosis of the gut microbiota, including uveitis and glaucoma. It has been shown that age related macular degeneration can be prevented or reversed using a diet that induces changes in the gut microbiota. The potential link between the gut microbiota as well as others types of microbiota such as the ocular surface microbiota and the development/progression of age related as well as inherited retinal degenerations and other degenerative eye diseases, has recently been broadened. Therefore, the pathogenesis of several eye diseases has recently been associated with a larger perception called the gut eye axis. This mini-review examines the potential mechanisms underlying the gut eye axis and suggests implications for the management of eye diseases. By understanding the modulation of the gut microbiota and its impact on eye disease, this mini-review provides insight into potential therapeutic interventions and avenues for future research.

Genetic Insights into the Association and Causality Between Blood Metabolites and Alzheimer's Disease

Background

Alzheimer's disease (AD) is an increasing public health concern with the aging of the global population. Understanding the genetic correlation and potential causal relationships between blood metabolites and AD may provide important insights into the metabolic dysregulation underlying this neurodegenerative disorder.

Objective

The aim of this study was to investigate the causal relationship between blood metabolites and AD using Mendelian randomization (MR) analysis.

Methods

Association data were obtained from three large-scale genome-wide association studies of 486 blood metabolites (N = 7,824), AD (71,880 cases and 383,378 controls), early-onset AD (N = 303,760), and late-onset AD (N = 307,112). Causal associations between blood metabolites and AD were assessed using inverse variance weighting (IVW), MR-Egger, and weighted median methods. Bidirectional two-sample MR analysis was used to identify causal blood metabolites. MR-PRESSO, MR-Egger, and Cochran-Q were used to quantify instrumental variable heterogeneity and horizontal pleiotropy.

Results

Using MR and sensitivity analysis, we identified 40 blood metabolites with potential causal associations with AD. After applying false discovery rate (FDR) correction, two metabolites, gamma-glutamylphenylalanine (OR = 1.15, 95% CI: 1.06-1.24, p = 3.88×10-4, q = 0.09) and X-11317 (OR = 1.16, 95% CI: 1.08-1.26, p = 1.14×10-4, q = 0.05), retained significant associations with AD. Reverse MR analysis indicated no significant causal effect of AD on blood metabolites. No significant instrumental variable heterogeneity or horizontal pleiotropy was found.

Conclusions

This two-sample MR study provides compelling evidence for a potential causal relationship between blood metabolic dysregulation and susceptibility to AD. Further investigation of the biological relevance of the identified metabolites to AD and additional supporting evidence is warranted.