Vasoactive intestinal peptide promotes host defense against enteric pathogens by modulating the recruitment of group 3 innate lymphoid cells.

Group 3 innate lymphoid cells (ILC3s) control the formation of intestinal lymphoid tissues and play key roles in intestinal defense. They express neuropeptide vasoactive intestinal peptide (VIP) receptor 2 (VPAC2), through which VIP modulates their function, but whether VIP exerts other effects on ILC3 remains unclear. We show that VIP promotes ILC3 recruitment to the intestine through VPAC1 independent of the microbiota or adaptive immunity. VIP is also required for postnatal formation of lymphoid tissues as well as the maintenance of local populations of retinoic acid (RA)-producing dendritic cells, with RA up-regulating gut-homing receptor CCR9 expression by ILC3s. Correspondingly, mice deficient in VIP or VPAC1 suffer a paucity of intestinal ILC3s along with impaired production of the cytokine IL-22, rendering them highly susceptible to the enteric pathogen Citrobacter rodentium This heightened susceptibility to C. rodentium infection was ameliorated by RA supplementation, adoptive transfer of ILC3s, or by recombinant IL-22. Thus, VIP regulates the recruitment of intestinal ILC3s and formation of postnatal intestinal lymphoid tissues, offering protection against enteric pathogens.

First-reported pediatric cases of American ginseng anaphylaxis and allergy.

BACKGROUND: Ginseng is a perennial herb used in traditional Chinese medicine, which has become increasingly popular world-wide due to its proposed medicinal effects. There are two major species of ginseng, Panax ginseng (Korean or Asian ginseng), and Panax quinquefolius (American ginseng). Although cases of allergy due to Korean ginseng have been reported in adults, there are no reported cases of allergy to American ginseng, and no reported cases of ginseng allergy in pediatric patients. CASE PRESENTATION: We present two unique cases of pediatric patients with suspected allergic reactions to American ginseng. The first patient is a 6-year-old girl who presented to the emergency department in anaphylaxis (urticaria and respiratory symptoms) minutes after inhaling powdered American ginseng. There was evidence of sensitization to American ginseng on skin prick testing (SPT) (13 × 12 mm wheal) and evidence of allergy to American ginseng on basophil activation testing, with a dose-dependent increase in expression of CD63 on basophils in response to American ginseng extract. The second patient is a 3-year-old boy who presented with recurrent allergic conjunctivitis upon exposure to aerosolized powdered ginseng, with evidence of sensitization to American ginseng on SPT (13 × 7 mm wheal), but with no evidence of IgE-mediated allergic reaction during oral challenge with American ginseng powder. CONCLUSIONS: These cases highlight two different allergic responses to American ginseng in pediatric patients. To our knowledge, these are the first reported cases of allergy to American ginseng, in addition to the first reported cases of allergy to ginseng in pediatric patients.

Goblet Cell Derived RELM-ß Recruits CD4+ T Cells during Infectious Colitis to Promote Protective Intestinal Epithelial Cell Proliferation.

Enterohemorrhagic Escherichia coli and related food and waterborne pathogens pose significant threats to human health. These attaching/effacing microbes infect the apical surface of intestinal epithelial cells (IEC), causing severe diarrheal disease. Colonizing the intestinal luminal surface helps segregate these microbes from most host inflammatory responses. Based on studies using Citrobacter rodentium, a related mouse pathogen, we speculate that hosts rely on immune-mediated changes in IEC, including goblet cells to defend against these pathogens. These changes include a CD4+ T cell-dependent increase in IEC proliferation to replace infected IEC, as well as altered production of the goblet cell-derived mucin Muc2. Another goblet cell mediator, REsistin-Like Molecule (RELM)-ß is strongly induced within goblet cells during C. rodentium infection, and was detected in the stool as well as serum. Despite its dramatic induction, RELM-ß's role in host defense is unclear. Thus, wildtype and RELM-ß gene deficient mice (Retnlb-/-) were orally infected with C. rodentium. While their C. rodentium burdens were only modestly elevated, infected Retnlb-/- mice suffered increased mortality and mucosal ulceration due to deep pathogen penetration of colonic crypts. Immunostaining for Ki67 and BrDU revealed Retnlb-/- mice were significantly impaired in infection-induced IEC hyper-proliferation. Interestingly, exposure to RELM-ß did not directly increase IEC proliferation, rather RELM-ß acted as a CD4+ T cell chemoattractant. Correspondingly, Retnlb-/- mice showed impaired CD4+ T cell recruitment to their infected colons, along with reduced production of interleukin (IL)-22, a multifunctional cytokine that directly increased IEC proliferation. Enema delivery of RELM-ß to Retnlb-/- mice restored CD4+ T cell recruitment, concurrently increasing IL-22 levels and IEC proliferation, while reducing mucosal pathology. These findings demonstrate that RELM-ß and goblet cells play an unexpected, yet critical role in recruiting CD4+ T cells to the colon to protect against an enteric pathogen, in part via the induction of increased IEC proliferation.