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. 2024 Feb;28(3):e18111.
doi: 10.1111/jcmm.18111. Epub 2024 Jan 18.

Low expression of TGF-β2 and matrilin2 in human aqueous humour with acute primary angle closure

Liming Wang  1 , Zhao Xu  1 , Yaru Hong  1 , Yan Liu  1 , Xiaomin Zhang  1 , Qiang Feng  2 , Dandan Zhang  2 , Kexi Chen  2 , Guli Humaer Yiming  2 , Xiaorong Li  1 , Aihua Liu  1 , Lijie Dong  1
Affiliations

Low expression of TGF-β2 and matrilin2 in human aqueous humour with acute primary angle closure

Liming Wang et al. J Cell Mol Med. 2024 Feb.

Abstract

Primary angle-closure glaucoma (PACG) is the leading cause of irreversible blindness in the world. Angle closure induced by pupil block and secondary iris synechia is the fundamental pathology of the PACG. The molecular mechanisms of angle closure have not yet been clearly illustrated. This study was designed to investigate the protein difference in the aqueous humour and explore new biomarker of the PACG. Aqueous humour (AH) was collected from patients with acute primary angle closure (APAC) and cataract (n = 10 in APAC group) and patients with cataract only (n = 10 in control group). Samples were pooled and measured using label-free proteome technology. Then, the differentially expressed proteins (DEPs) were verified by ELISA using independent AH samples (n = 20 each group). More than 400 proteins were revealed in both groups through proteomics. Comparing the two groups, there were 91DEPs. These proteins participate in biological activities such as inflammation, fibrosis, nerve growth and degeneration and metabolism. We found that the expression of transforming growth factor-β2 and matrilin2 was downregulated in the APAC group. The two proteins are related to inflammation and extracellular matrix formation, which might be involved in angle closure. This study characterized DEPs in AH of the APAC and found a downregulated protein matrilin2.

Keywords: ELISA; TGF-β2; acute primary angle closure; aqueous humour; glaucoma; matrilin2; proteome.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Examination of the acute primary angle‐closure (APAC) patients. Corneal oedema, shallow anterior chamber, dilated pupil and local iris atrophy were observed via slit‐lamp microscopy in the eye of APAC patient (A). The closed angle and bulging iris are shown based on ultrasound biomicroscopy in the eye of the APAC patient (B). The optic disc had clear boundaries, close‐to‐normal colour and a piece of flame‐like bleeding beside the optic disc, representing an attack sign in the fundus image (C). The thickness of the nerve fibre layer was within the normal range in optical coherence tomography (D).
FIGURE 2
FIGURE 2
Workflow of proteomic technology and heatmap of the aqueous humour proteins in acute primary angle‐closure (APAC) group and controls. The workflow shows aqueous humour (AH) collection, protein digestion, peptide abundance recognition, spectral count with label‐free proteomic technology, data analysis and enzyme‐linked immunosorbent assay (ELISA) verification (A). The heatmap shows protein expression in the AH of the APAC group (A1, A2) and controls (C1, C2). Red represents upregulated proteins and blue represents downregulated proteins (B).
FIGURE 3
FIGURE 3
Classification of significantly DEPs. According to their function, the DEPs are determined to be mainly involved in inflammation, metabolism, the nerve system, adhesion and fibrosis. Arrows represent protein increase or decrease in the APAC aqueous humour (AH) in comparison to control group.
FIGURE 4
FIGURE 4
Gene Ontology (GO) analysis of genes of DEPs in the acute primary angle‐closure (APAC) group compared with the cataract group. Illustrated in the histogram, GO analysis includes the biological processes (BPs: green), cellular components (CCs: orange) and molecular functions (MFs: blue). The protein‐encoding genes are mainly enriched in transport, cell motility, cell adhesion, cell proliferation and cell death processes. They are determined to be located in the extracellular region, membrane, cytoplasm, nucleus and cytoskeleton and to participate in metal ion binding, receptor binding and transmembrane transporter activity.
FIGURE 5
FIGURE 5
Analysis of the signalling pathways of significantly DEPs in APAC group compared with control by the Kyoto Encyclopedia of Genes and Genomes (KEGG). Based on the p‐value, the DEPs were mainly enriched in the lysosome, axon, glycolysis/gluconeogenesis, extracellular matrix (ECM)–receptor interaction and biosynthesis of amino acids signalling pathways. Those proteins participate in some inflammation signalling pathways, such as the toll‐like receptor signalling pathway, MAPK signalling pathway and IL‐17 signalling pathway.
FIGURE 6
FIGURE 6
Protein–protein interaction (PPI) network of all DEPs. The PPI reflects the interactions among all significantly DEPs between the APAC group and control group. Proteins marked with red rectangles are associated with the PACG based on their biological function.
FIGURE 7
FIGURE 7
Verification of DEPs by ELISA. The MATN2, ANXA1 and TGF‐β2 in the aqueous humour (AH) are downregulated in the APAC group compared to the control. The expression of CDH4 in the AH is not significantly difference between the APAC and control group.
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