YKL-40 is a local marker for inflammation in patients with pseudoexfoliation syndrome

Effects of Humanin G (HNG) on angiogenesis and neurodegeneration markers in Age-related Macular Degeneration (AMD)

Advanced stages of Age-related Macular Degeneration (AMD) are characterized by retinal neurodegeneration and aberrant angiogenesis, and mitochondrial dysfunction contributes to the pathogenesis of AMD. In this study, we tested the hypothesis that Humanin G (HNG), a cytoprotective mitochondrial-derived peptide, positively regulates cell proliferation, cell death, and the protein levels of angiogenesis and neurodegeneration markers, in normal (control) and AMD RPE transmitochondrial cybrid cell lines. These normal and AMD RPE transmitochondrial cybrid cell lines had identical nuclei derived from mitochondria-deficient ARPE-19 cell line, but differed in mitochondrial DNA (mtDNA) content that was derived from clinically characterized AMD patients and normal (control) subjects. Cell lysates were extracted from untreated and HNG-treated AMD and normal (control) cybrid cell lines, and the Luminex XMAP multiplex assay was used to examine the protein levels of angiogenesis and neurodegeneration markers. Humanin G reduced Caspase-3/7-mediated apoptosis, improved cell proliferation, and normalized the protein levels of angiogenesis and neurodegeneration markers in AMD RPE cybrid cell lines, thereby suggesting Humanin G's positive regulatory role in AMD.

Analysis of genetically determined gene expression suggests role of inflammatory processes in exfoliation syndrome

BACKGROUND

Exfoliation syndrome (XFS) is an age-related systemic disorder characterized by excessive production and progressive accumulation of abnormal extracellular material, with pathognomonic ocular manifestations. It is the most common cause of secondary glaucoma, resulting in widespread global blindness. The largest global meta-analysis of XFS in 123,457 multi-ethnic individuals from 24 countries identified seven loci with the strongest association signal in chr15q22-25 region near LOXL1. Expression analysis have so far correlated coding and a few non-coding variants in the region with LOXL1 expression levels, but functional effects of these variants is unclear. We hypothesize that analysis of the contribution of the genetically determined component of gene expression to XFS risk can provide a powerful method to elucidate potential roles of additional genes and clarify biology that underlie XFS.

RESULTS

Transcriptomic Wide Association Studies (TWAS) using PrediXcan models trained in 48 GTEx tissues leveraging on results from the multi-ethnic and European ancestry GWAS were performed. To eliminate the possibility of false-positive results due to Linkage Disequilibrium (LD) contamination, we i) performed PrediXcan analysis in reduced models removing variants in LD with LOXL1 missense variants associated with XFS, and variants in LOXL1 models in both multiethnic and European ancestry individuals, ii) conducted conditional analysis of the significant signals in European ancestry individuals, and iii) filtered signals based on correlated gene expression, LD and shared eQTLs, iv) conducted expression validation analysis in human iris tissues. We observed twenty-eight genes in chr15q22-25 region that showed statistically significant associations, which were whittled down to ten genes after statistical validations. In experimental analysis, mRNA transcript levels for ARID3B, CD276, LOXL1, NEO1, SCAMP2, and UBL7 were significantly decreased in iris tissues from XFS patients compared to control samples. TWAS genes for XFS were significantly enriched for genes associated with inflammatory conditions. We also observed a higher incidence of XFS comorbidity with inflammatory and connective tissue diseases.

CONCLUSION

Our results implicate a role for connective tissues and inflammation pathways in the etiology of XFS. Targeting the inflammatory pathway may be a potential therapeutic option to reduce progression in XFS.

Is pseudoexfoliation syndrome associated with vitreoretinal interface abnormalities?

BACKGROUND

To evaluate vitreoretinal interface abnormalities in patients with pseudoexfoliation (PEX) syndrome.

METHODS

This case-control study was performed in 136 patients diagnosed with unilateral PEX (PEX group) and 139 age- and sex-matched healthy volunteers (Control group). Both the affected and contralateral eyes were evaluated in the PEX group and the right eye was evaluated in the Control group. Vitreoretinal interface abnormalities and posterior vitreous detachment (PVD) were evaluated on optical coherence tomography (OCT) examination.

RESULTS

The incidences of incomplete and complete PVD were significantly higher in the affected than contralateral eye in the PEX group and in the right eye in the Control group (P = 0.009, P = 0.012 and P = 0.004, P = 0.017, respectively). The rates of 'no PVD' were significantly higher in the contralateral eye in the PEX group and the Control group compared to the affected eye in the PEX group (P = 0.003 and P = 0.001, respectively). The odds ratio for incomplete PVD was 3.1 in PEX eyes compared to the contralateral eye in the PEX group and 3.9 compared to the Control group. The rate of epiretinal membranes (ERMs) in the affected eye was significantly different from the contralateral eye in the PEX and Control groups (P < 0.001 and P < 0.001, respectively). The odds ratio for ERM in PEX eyes was 3.51 compared to the contralateral eye in the PEX group and 4.23 compared to the Control group. In the presence of incomplete PVD, the odds ratio for ERM development was 3.81 in PEX eyes.

CONCLUSIONS

We detected high rates of ERMs and incomplete PVD in patients with PEX. It is important to evaluate and follow up PEX cases in terms of vitreoretinal interface abnormalities.