The current state of two-dimensional electrophoresis with immobilized pH gradients

Screening of differential serum proteins in patients with hepatic fibrosis

AIM: To compare and analyze the expression difference of proteins between hepatic fibrosis serum and normal human serum and to identify potential serum markers for human hepatic fibrosis.

METHODS: Serum samples were collected from 6 healthy subjects and 6 patients with hepatic fibrosis following normal protocols. The serum samples of these two groups were mixed into one respectively of equal volume. Albumin and IgG removal were carried out and serum total proteins were extracted. 2-DE was used to isolate the total proteins using pH 4-7 L, 18 cm IPG strip, and SDS-PAGE. Silver nitrate stain was applied afterwards. ImageMaster 2D Platinum Softwared (Version 5) was employed to analyze the 2-DE results. ELISA was adopted to verify the expression changes of some differential proteins.

RESULTS: The 2-DE matching rate was 89.58% between the two groups. From the two groups, 517 differential protein spots were identified, among which 24 with differential expression above three times were singgled out and MALDI-TOF-MS analysis was carried out on them. Eight proteins were identified, including transferring, apolipoprotein A-IV, T-cell receptor b, haptoglobin, serum albumin and serum albumin precursor. Up-regulated expression was observed in 3 proteins and down-regulated expression in 5 proteins in the hepatic fibrosis serum group. As compared with that in normal serum, haptoglobin and apolipoprotein A-IV expression were down-regulated in hepatic fibrosis serum, which was consistent with the results of 2-DE.

CONCLUSION: Compared with the normal subject group, the serum in the hepatic fibrosis group showed differential expression in protein profile. The proteins of differential expression are expected to be the serum markers for hepatic fibrosis.

Sequential proteomic characteristics of AGS cells co-cultured with H. pylori strain

AIM: To analyze the differential expression of proteome in human gastric adenocarcinoma epithelial AGS cells co-cultured with H. pylori.

METHODS: The samples of AGS cells co-cultured with H. pylori 26695 strain at three time-points (0.5, 2 and 4 h) were collected and separated by 2-dimensional polyacrylamide gel electrophoresis (2-DE) technique and computer-assisted image analysis was used to analyze the differential proteomic expression. The significantly differentially expressed proteins were recognized and identified with the 4700 proteomics discovery system.

RESULTS: There were 66 protein spots that were significantly differentially expressed at different time-points, 34 (corresponding to 16 kinds of proteins) of which were identified with matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF-TOF). At 2-h time-point, 8 kinds of proteins were up-regulated obviously, of which 2 originated from the cells and 6 from H. pylori. At the 4-h time-point, 4 kinds of cell-originated proteins were down-regulated, and 4 kinds of new proteins were observed. Succinate dehydrogenase iron-sulfur subunit, HpaA, HSP 60 and peroxiredoxin were up-regulated at the early stage of co-infection. However, at the late stage of co-infection, two cell-originated proteins (cyclophilin A, nascent-polypeptide-associated complex alpha polypeptide) and two H. pylori-originated proteins (urease, non-heme iron protein) were found to express.

CONCLUSION: During the interaction between AGS cells and H. pylori, the expression of proteins is associated with adhesion change in the early stage, followed by a favorable alteration in the survival and proliferation of H. pylori as well as immunologic escape and pathological erosion.