Allium sativum (garlic) suppresses leukocyte inflammatory cytokine production in vitro:: Potential therapeutic use in the treatment of inflammatory bowel disease

Background: Cytokines involved in inflammatory bowel disease QBD) direct a predominantly cell-mediated T-helper-1 (Th1) immune response. The nonspecific anti-inflammatory treatment being used in the management of patients with IBD has not changed much since the 1970s and new therapeutic agents are keenly sought. Several compounds isolated from Allium sativum (garlic) modulate leukocyte cell proliferation and cytokine production. Methods: To investigate the possible therapeutic effects of garlic in the treatment of patients with IBD, whole blood and peripheral blood mononuclear cells (PBMCs) were stimulated in the presence of various concentrations of garlic extract and the effect on leukocyte cytokine production was determined in vitro using multiparameter flow cytometry. Results: Monocyte interleukin (IL)-12 production was inhibited significantly in the presence of low concentrations of garlic extract (greater than or equal to0.1 mug/ml total protein). Monocyte IL-10 production increased significantly and monocyte tumor necrosis factor-alpha (TNF-alpha), IL-1alpha., IL-6, IL-8, T-cell interferon-gamma (IFN-gamma), IL-2, and TNF-alpha decreased significantly in the presence of greater than or equal to10 mug/ml garlic extract. Twenty to fifty percent of the immunomodulatory activity of garlic extract on cytokine production was acid labile. The inhibitory activity of methylprednisolone, a commonly used anti-inflammatory in IBD, with garlic on leukocyte cytokine production was additive. Conclusions: By inhibiting Th1 and inflammatory cytokines while upregulating IL-10 production, treatment with garlic extract may help to resolve inflammation associated with IBD. An in vivo animal model study needs to be undertaken to determine the significance of these in vitro findings.