Awareness of the immunological underpinnings of host-parasite interactions may reveal immune signaling pathways that could be used to treat inflammatory disease in humans. Previously we showed that infection with the rat tapeworm, Hymenolepis diminuta, used as a model helminth, or systemic delivery of worm antigen (HdAg) significantly reduced the severity of dinitrobenzene sulfonic acid (DNBS)-induced colitis in mice. Extending these analyses, intraperitoneal injection of HdAg dosedependently suppressed dextran sodium sulfate (DSS)-induced colitis, and this was paralleled by reduced gamma interferon (IFN-␥), interleukin-17 (IL-17), and tumor necrosis factor alpha (TNF-␣) production and increased IL-10 production from mitogen-activated splenocytes. Until relatively recently, analysis of the host response to infection with helminth parasites focused almost invariably on TH2 immunity; however, it has emerged that helminth parasites trigger a complex regulatory network in their mammalian hosts that is characterized by cytokines (e.g., interleukin-10 [IL-10] and transforming growth factor ␤ [TGF-␤]) and cellular components (e.g., regulatory macrophages and T cells) (1). Indeed, the development of an immunoregulatory environment likely contributes to the chronicity of helminth infection and asymptomatic disease. Moreover, individuals infected with a variety of species of helminths can be protected from concomitant disease as demonstrated in animal models of multiple sclerosis (2-4), joint (5-7) and gut (8-10) inflammation, and allergy (11, 12). In addition, treatment with somatic extracts or secreted products can significantly attenuate disease severity in models of inflammatory diseases (13-15), raising the possibility that isolation and purification of helminth-derived molecules could result in new anti-inflammatory drugs.The inverse relationship between the geographical distribution of inflammatory bowel disease (IBD) (i.e., Crohn's disease and ulcerative colitis) and areas of endemic helminth infection suggests that infection with helminth parasites may protect against IBD (16). Testing this hypothesis, infections with Trichinella spiralis, Schistosoma mansoni, and Heligmosomoides polygyrus were shown to inhibit inflammation in dinitrobenzene sulfonic acid (DNBS)-and dextran-sodium sulfate (DSS)-induced colitis and piroxicam-treated IL-10 Ϫ/Ϫ mice, respectively (8, 9, 17)-all established mouse models of colitis that share some similarities to human IBD. Similarly, and as an alternative to viable infection, systemic administration of helminth-derived antigens can ameliorate colitis in animal models. As examples, the excretory/secretory (E/S) products from adult T. spiralis reduced DSS-induced colitis (18) and S. mansoni egg antigens ameliorated immunemediated colitis (19): in both instances, suppression of TH1 and TH17 cytokines correlated with the beneficial anticolitic effect. While encouraging, the precise mechanism of action of any helminth-derived extract or molecule to block colitis or other inflammatory dis...

Infection with helminth parasites has been explored as a treatment for autoimmune and inflammatory diseases. As helminth antigens have potent immunomodulation properties capable of inducing regulatory programs in a variety of cell types, transferring cells treated with helminth antigens represents a novel extension to helminth therapy. Previous work determined that transfer of bone marrow-derived dendritic cells (DC) pulsed with a crude extract of the tapeworm Hymenolepis diminuta (HD) can suppress colitis in recipient mice. The present study explored the mechanism of disease suppression and the importance of interleukin (IL)-4 signaling. Transfer of HD-DCs suppressed dinitrobenzene sulfonic acid (DNBS)-induced colitis through activation of recipient IL-4 receptor-α. The transferred HD-DCs required IL-4Rα and the capacity to secrete IL-10 to drive IL-4 and IL-10 production and to suppress colitis in recipient mice. Treatment of DCs with IL-4 evokes an alternatively activated phenotype, but adoptive transfer of these cells did not affect the outcome of colitis. Collectively, these studies demonstrate the complexity between IL-4 and IL-10 in donor cells and recipient, and the requirement for parasite- and host-derived factors in this novel form of cell therapy. Thus IL-4Rα signaling is revealed as a pathway that could be exploited for helminth antigen cell-based therapy.