4C and ?andD).D). concern of putative side effects) may lead to the development of novel therapies for human idiopathic disorders such as inflammatory bowel disease. INTRODUCTION Until relatively recently, analysis of the host response to contamination 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 MK-4101 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 contamination and asymptomatic disease. Moreover, individuals infected with a variety of species of helminths can be guarded from concomitant disease as exhibited in animal models of multiple sclerosis (2,C4), joint (5,C7) and gut (8,C10) 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,C15), 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 contamination suggests that contamination with helminth parasites may protect against KDM3A antibody IBD (16). Screening this hypothesis, infections with were shown to inhibit inflammation in dinitrobenzene sulfonic acid (DNBS)- and dextran-sodium sulfate (DSS)-induced colitis and piroxicam-treated IL-10?/? 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 contamination, systemic administration of helminth-derived antigens can ameliorate colitis in animal models. As examples, the excretory/secretory (E/S) products from adult reduced DSS-induced colitis (18) and egg antigens ameliorated immune-mediated 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 diseases is not well understood. In some of the first studies on helminth-induced suppression of colitis, we found that mice infected with five cysticercoids of MK-4101 the rat tapeworm, over the 3 days of DNBS treatment significantly reduced the severity of inflammation in the colon (21). The relatively minor ability of contamination with to alleviate DSS-induced disease was puzzling. Consequently, we tested the hypothesis that a crude extract of adult antigens (HdAg) would attenuate colitis induced by DSS. The data herein reveal that HdAg treatments significantly reduce the severity of DSS colitis; intraperitoneal delivery of the HdAg resulted in recruitment of CCR2+ PD-L1+ monocyte-like cells. Analysis of these CCR2+ PD-L1+ F4/80+ Ly6C+ Gr-1lo MK-4101 cells revealed their capacity to induce IL-10 secretion by T cells. Adoptive transfer of these cells inhibited DSS-induced colitis in the recipient mice, indicating the potential for helminth-evoked CCR2+ PD-L1+ F4/80+ Ly6C+ Gr-1lo cells to suppress intestinal inflammation. MATERIALS AND METHODS Ethics. All of the experiments conducted in this study conformed to Canadian national guidelines on animal use in experimentation as administered by the Health Science Animal Care Committee under ethics protocol AC-13-005. Generation of crude antigens (HdAg). Adult parasites were flushed from the small intestine of rats (Charles River, QC, Canada) with sterile phosphate-buffered saline (PBS), treated with antibiotics (gentamicin answer; Sigma, MK-4101 St. Louis, MO]) for 2 h, centrifuged, and then homogenized in sterile PBS on ice using MK-4101 a Polytron PT1200 (Kinematica AG, Switzerland). The homogenate was centrifuged twice at 4,000 rpm for 30 min at 4C, the PBS-soluble supernatant was collected, and the pellet was discarded. Endotoxin measurement (ToxinSensor Chromogenic LAL kit; GenScript, Piscataway, NJ) revealed 65 pg lipopolysaccharide (LPS)/1 mg of HdAg extract. The protein concentration in the HdAg preparations was determined by the Bradford assay (Bradford reagent; Sigma-Aldrich, St. Louis.