Differential Expression and Localization of ADAMTS Proteinases in Proliferative Diabetic Retinopathy

Ranibizumab Modifies the Expression of Metalloproteinases and Their Tissue Inhibitors in Peripheral Blood Mononuclear Cells in Patients with Exudative Age-Related Macular Degeneration

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of vision loss in people over 60 years of age. Despite research, the causes of AMD remain unclear. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are known to be involved in AMD development, and anti-vascular endothelial growth factor therapy has revolutionized its treatment. This study aims to analyze the changes in gene expression in MMPs and TIMPS in patients with neovascular AMD before and after three doses of ranibizumab.

METHODS

The study involved 29 patients with neovascular AMD treated with ranibizumab. Peripheral blood mononuclear cells were collected before treatment and 24 h after the third dose of ranibizumab. We assessed MMP and TIMP gene expression profiles through oligonucleotide microarrays and validated selected differential genes using RT-qPCR.

RESULTS

A statistically significant change in the expression of six MMP- and TIMP-related genes was observed using oligonucleotide microarray. The mRNA levels of the two genes with the most significant fold changes, MMP15 and TIMP2, were then quantified using RT-qPCR. The results confirmed a statistically significant increase in MMP15 expression and a decrease in TIMP2 levels, although this change was not statistically significant in the group before and after the third dose of ranibizumab.

CONCLUSION

Ranibizumab affects the systemic expression of MMP and TIMP-related genes in patients with neovascular AMD. Results from our exploratory study suggest that MMP15, in particular, may play a role in the treatment response, but further research is necessary.

Fibrillin-1 regulates endothelial sprouting during angiogenesis

Fibrillin-1 is an extracellular matrix protein that assembles into microfibrils which provide critical functions in large blood vessels and other tissues. Mutations in the fibrillin-1 gene are associated with cardiovascular, ocular, and skeletal abnormalities in Marfan syndrome. Here, we reveal that fibrillin-1 is critical for angiogenesis which is compromised by a typical Marfan mutation. In the mouse retina vascularization model, fibrillin-1 is present in the extracellular matrix at the angiogenic front where it colocalizes with microfibril-associated glycoprotein-1, MAGP1. In Fbn1C1041G/+ mice, a model of Marfan syndrome, MAGP1 deposition is reduced, endothelial sprouting is decreased, and tip cell identity is impaired. Cell culture experiments confirmed that fibrillin-1 deficiency alters vascular endothelial growth factor-A/Notch and Smad signaling which regulate the acquisition of endothelial tip cell/stalk cell phenotypes, and we showed that modulation of MAGP1 expression impacts these pathways. Supplying the growing vasculature of Fbn1C1041G/+ mice with a recombinant C-terminal fragment of fibrillin-1 corrects all defects. Mass spectrometry analyses showed that the fibrillin-1 fragment alters the expression of various proteins including ADAMTS1, a tip cell metalloprotease and matrix-modifying enzyme. Our data establish that fibrillin-1 is a dynamic signaling platform in the regulation of cell specification and matrix remodeling at the angiogenic front and that mutant fibrillin-1-induced defects can be rescued pharmacologically using a C-terminal fragment of the protein. These findings, identify fibrillin-1, MAGP1, and ADAMTS1 in the regulation of endothelial sprouting, and contribute to our understanding of how angiogenesis is regulated. This knowledge may have critical implications for people with Marfan syndrome.