BackgroundPreoperative treatment of anti-vascular endothelial growth factor (VEGF) agents is extensively used in proliferative diabetic retinopathy (PDR), but the molecular mechanism is not fully understood. The objective of this research is to observe change of protein profile induced by ranibizumab (an anti-VEGF agent) in vitreous humor from PDR patients and reveal the effects of anti-VEGF treatment on PDR.MethodsA proteomic method was used to identify differentially expressed proteins in vitreous humor. Untreated PDR patients were defined as PDR group, while those who treated with intravitreal injection of ranibizumab (IVR) were defined as IVR. Gene Ontology (GO) annotation and REACTOME pathways were obtained from DAVID Bioinformatics Resources. Intravitreal level of apolipoprotein C-I (APOC1), serpin peptidase inhibitor clade A member 5 (SERPINA5), tissue inhibitor of metalloproteinases (TIMP2), and keratin 1 (KRT1) were determined by enzyme-linked immuno sorbent assay (ELISA).Results339 differentially expressed proteins were identified in response to IVR. The most notable GO annotation describes the altered proteins was “innate immune response”. The most notable REACTOME pathway was “platelet degranulation”. ELISA result showed increased level of APOC1, SERPINA5, KRT1 and a decreased level of TIMP2 in PDR group compared with IVR.ConclusionsIn addition to decreasing VEGF level, ranibizumab is associated with change of human vitreous protein profile in patients with PDR, in which the differential proteins are involved in immune response, platelet degranulation, complement activation etc., suggesting that the effects of VEGF are involved in these signaling pathways.Electronic supplementary materialThe online version of this article (10.1186/s12014-018-9187-z) contains supplementary material, which is available to authorized users.

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Purpose To examine the difference in the vitreal protein profiles of patients with proliferative diabetic retinopathy (PDR) with and without preoperative intravitreal conbercept (IVC) treatment. Methods Liquid chromatography-tandem mass spectrometry- (LC-MS/MS-) based proteomic methods were used to determine the protein profiles of the vitreous humor in patients with PDR treated with (IVC group; n = 9) and without (PDR group; n = 8) preoperative IVC. Gene ontology (GO) annotation and REACTOME pathway analysis were obtained to overview differentially expressed proteins between each group. Intravitreal levels of apolipoprotein A-II (APOA2) and ceruloplasmin (CP) were measured using enzyme-linked immunosorbent assays. Results 307 proteins were expressed differentially between PDR and IVC groups, including 218 proteins downregulated in response to IVC. The most notable GO annotations in level 3 and REACTOME pathways describing the differentially expressed proteins were “innate immune response” and “platelet degranulation.” The intravitreal levels of APOA2 and CP were lower in the IVC group than in the PDR group (p < 0.01). Conclusions In addition to decreasing the intravitreal vascular endothelial growth factor level, IVC may alter the vitreal protein profile in patients with PDR, with the differentially regulated proteins involved in the immune response, platelet degranulation, complement activation, and inflammation.

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