IFNG and irritable bowel syndrome: As shown in Figure 3, the IFN-γ protein level showed a trend toward up-regulation in PI-IBS patients (0.25 ± 0.02) but not in non-PI-IBS patients (0.22 ± 0.01) or healthy people (0.21 ± 0.01); however, the differences were not significant (both P > 0.05).