Vascular endothelial growth factor/connective tissue growth factor and proteomic analysis of aqueous humor after intravitreal conbercept for proliferative diabetes retinopathy.

Aim: To investigate the role of connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF) in the protein profile of the aqueous humor in patients with proliferative diabetic retinopathy (PDR) following intravitreal injection of conbercept.

Methods: This study included 72 PDR patients and 8 cataract patients as controls. PDR patients were divided into 3 groups according to the intervals of 3, 5, and 7d between intravitreal conbercept (IVC, 0.5 mg/0.05 mL) injection and pars plana vitrectomy (PPV) performed. Aqueous humor samples were collected before and after IVC and PPV for VEGF and CTGF levels detected with enzyme-linked immunosorbent assay (ELISA). The differential proteomics of 10 patients who underwent PPV surgery 5d after IVC and 8 normal controls was studied, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed on the data, and the protein interaction network of 23 differential proteins was studied.

Results: Post-IVC, VEGF levels decreased and CTGF levels increased significantly in aqueous humor, with the CTGF/VEGF ratio rising significantly at all intervals. Liquid chromatography tandem mass spectrometry (LC-MS/MS) identified differentially expressed proteins between pre- and post-IVC samples. GO and KEGG analyses revealed involvement in immune response, stress response, complement and coagulation cascades, ferroptosis, and PPAR signaling pathways. PPI analysis highlighted key proteins like APOA1, C3, and transferrin (TF). ELISA assay confirmed the differential expression of proteins such as HBA1, SERPINA1, COL1A1, and ACTB, with significant changes in the IVC groups.

Conclusion: The study demonstrates that IVC effectively reduces VEGF levels while increasing CTGF levels, thereby modifying the CTGF/VEGF ratio, and IVC significantly alters the protein profile in the aqueous humor of patients with PDR. Proteomic analysis reveals that these changes are associated with critical biological pathways and protein interactions involved in immune response, stress response, and cellular metabolism.