Serum proteomic profiling associated with immune system impaired by stress using ProteinChip technology

We set out to use proteomic profiling as a means of defining serum peptides that are indicative of a stress response related to an impact on the immune system. Two types of mouse models with the immune response impaired under stress (restraint stress and thermal stress) comprised the stressed groups (n = 10 in each group), while mice without stress represented the control group (n = 10). ProteinChip technology (surface-enhanced laser desorption/ionization time-of-flight mass spectrometry) was used to investigate the serum proteomic profiles. Histopathological examination of spleens from the stressed and control groups was performed to select appropriate individuals. Compared with the spleens of normal mice, those of mice subjected to restraint and thermal stress had decreased white pulp and lymphoid nodules, and their distribution and structure changed irregularly. Pathological changes occurred in all individuals in both stressed groups. The m/z values of the protein peaks ranged from 1,500 to 50,000 daltons and were mainly in the 2,000- to 20,000-dalton range. One hundred and fifty protein peaks were detected in the three groups. Four downregulated universal stress protein peaks with m/z of 4,389, 5,341, 5,526, and 6,252 were finally selected. Unexpectedly, no upregulated universal stress protein peaks were detected. These results suggested that impairment of the immune system results from inhibition of growth-promoting factors associated with the immune system. Identified protein peaks may be biomarkers of the impaired immune system under stress.