TNF and irritable bowel syndrome: As shown in Figure 6(b), even though the detected cytokines were all decreased significantly in PI-IBS rats, the levels of Th1-related cytokines, TNF-α and IFN-γ, were decreased more obviously (51% decrease in TNF-α, 42% decrease in IFN-γ) than others (14% decrease in IL-10, 19% decrease in IL-6).