Elevated CD154 (CD40 ligand) synthesis in T-cells from allergic patients after nonspecific stimulation in vitro.

The interaction of the CD154 molecule (CD40 ligand, gp39) on activated T-cells with the CD40 antigen on B-cells seems to play a key role in immunoglobulin class switching. We aimed to compare the capacity of intracellular CD154 expression after nonspecific stimulation with phorbol-12-myristate-13-acetate and ionomycin on separated T-cells from allergic patients and healthy donors. We analyzed blood from 104 patients allergic to grass pollen, house dust mites or birch pollen, and from 44 healthy donors. Lymphocytes were isolated using a density gradient and B-cells were extracted by magnet-activated cell separation (MACS) using anti-CD19 microbeads. Cells were nonspecifically stimulated for 5 h, permeabilized and stained with anti-CD154 for fluorescence-activated cell sorter analysis. It was found that stimulation induced a 1.4% increase of intracellular CD154+ T-cells; a 4.6% increase of mean channel fluorescence of all T-cells from healthy donors; a 6.1% increase in intracellular CD154+ T-cells; and a 28.1% increase of mean channel fluorescence of all T-cells from allergic patients. The data demonstrated an elevated capability of B-cell independent CD154 synthesis in T-cells from allergic patients when compared to healthy individuals. It is possible that the enhanced IgE production of B-cells from allergic patients might be partly due to the phenomena described.

Elevated nonspecific plasma proteins in allergic patients.

Several allergen-specific plasma proteins, such as IgE and IgG subclasses, are commonly used for the evaluation of grade of allergy. In the present investigation, we compared the concentration of various nonspecific plasma proteins, mostly known as inflammation markers, in an allergic and a healthy population. Plasma from 130 children with single inhalation allergies to grass pollen, birch pollen, or house dust mites as well as from 42 healthy children was obtained during the symptom-free period. Patients showed symptoms including allergic rhinitis, dermatitis, and asthma with one single radioallergosorbent test (RAST) class 3 or higher. Plasma concentrations of soluble intercellular adhesion molecule-1(sICAM-1), soluble interleukin-2 receptor(sIL-2R), sE-selectin, and soluble vascular cell adhesion molecule-1 (1sVCAM-1) were analyzed by enzyme linked immunosorbent assay (ELISA) technique. Concentrations of sICAM-1 and sE-selectin were significantly increased in all patients compared to controls. In the single allergen groups, sICAM-1 elevation was significant in the grass and mite groups, but not in the birch group; while sE-selection increase was significant in the birch and mite groups, but not in the grass group. The elevation of sIL-2R in the allergic patients was obvious in each single allergen group, but not significant. No difference was observed in sVCAM-1 expression. In two groups of patients with mean age of 9.5 years versus 17.5 years, the analyzed parameters were not age dependent. The increased proteins may be useful as additional markers for efficacy and follow-up investigations of allergy therapies.

CX3CR1⁺ cells facilitate the activation of CD4 T cells in the colonic lamina propria during antigen-driven colitis.

Dendritic cells (DCs) and macrophages populate the intestinal lamina propria to initiate immune responses required for the maintenance of intestinal homeostasis. To investigate whether CX3CR1(+) phagocytes communicate with CD4 T cells during the development of transfer colitis, we established an antigen-driven colitis model induced by the adoptive transfer of DsRed OT-II cells in CX3CR1(GFP/+) × RAG(-/-) recipients challenged with Escherichia coli expressing ovalbumin (OVA) fused to a cyan fluorescent protein (CFP). After colonization of CX3CR1(GFP/+) × RAG(-/-) animals with red fluorescent E. coli pCherry-OVA, colonic CX3CR1(+) cells but not CD103(+) DCs phagocytosed E. coli pCherry-OVA. Degraded bacterial-derived antigens are transported by CD103(+) DCs to mesenteric lymph nodes (MLNs), where CD103(+) DCs prime naive T cells. In RAG(-/-) recipients reconstituted with OT II cells and gavaged with OVA-expressing E. coli, colonic CX3CR1(+) phagocytes are in close contact with CD4 T cells and presented bacterial-derived antigens to CD4 T cells to activate and expand effector T cells.

Hypertrophy of infected Peyer's patches arises from global, interferon-receptor, and CD69-independent shutdown of lymphocyte egress.

Lymphoid organ hypertrophy is a hallmark of localized infection. During the inflammatory response, massive changes in lymphocyte recirculation and turnover boost lymphoid organ cellularity. Intriguingly, the exact nature of these changes remains undefined to date. Here, we report that hypertrophy of Salmonella-infected Peyer's patches (PPs) ensues from a global "shutdown" of lymphocyte egress, which traps recirculating lymphocytes in PPs. Surprisingly, infection-induced lymphocyte sequestration did not require previously proposed mediators of lymphoid organ shutdown including type I interferon receptor and CD69. In contrast, following T-cell receptor-mediated priming, CD69 was essential to selectively block CD4(+) effector T-cell egress. Our findings segregate two distinct lymphocyte sequestration mechanisms, which differentially rely on intrinsic modulation of lymphocyte egress capacity and inflammation-induced changes in the lymphoid organ environment.

CX(3)CR1(+) macrophages support IL-22 production by innate lymphoid cells during infection with Citrobacter rodentium.

Innate immune cells, such as intestinal epithelial cells, dendritic cells (DCs), macrophages, granulocytes, and innate lymphoid cells provide a first line of defence to enteric pathogens. To study the role of CX(3)CR1(+) DCs and macrophages in host defence, we infected CX(3)CR1-GFP animals with Citrobacter rodentium. When transgenic CX(3)CR1-GFP animals are infected with the natural mouse pathogen C. rodentium, CX(3)CR1(-/-) animals showed a delayed clearance of C. rodentium as compared with (age- and sex-matched) wild-type B6 animals. The delayed clearance of C. rodentium is associated with reduced interleukin (IL)-22 expression. In C. rodentium-infected CX(3)CR1-GFP animals, IL-22 producing lymphoid-tissue inducer cells (LTi cells) were selectively reduced in the absence of CX(3)CR1. The reduced IL-22 expression correlates with decreased expression of the antimicrobial peptides RegIIIß and RegIIIγ. The depletion of CX(3)CR1(+) cells by diphtheria toxin injection in CX(3)CR1-GFP × CD11c.DOG animals confirmed the role of CX(3)CR1(+) phagocytes in establishing IL-22 production, supporting the clearance of a C. rodentium infection.

Review on the influence of stress on immune mediators, neuropeptides and hormones with relevance for inflammatory bowel disease.

Stress has long been postulated to influence the progression of inflammatory bowel disease (IBD). Our current understanding of the relationship between stress and IBD is still limited, and hence explanation for the occurrence of relapses has remained largely speculative. Stress affects the immune system, the neuroendocrine system and the intestinal epithelia. Stress induces the release of pro-inflammatory Th1 cytokines and neuropeptides, such as tachykinins. Thereby, stress may induce alterations of the intestinal epithelium via the interaction of the neuroendocrine and immune system and may induce relapses of IBD. The present review focuses on this network and highlights the role of distinct mediators and mechanisms, i.e. neurotransmitters, hormones and immune cells, which are involved in the response to stress on the one hand, and contribute to the onset, progression or relapses of IBD on the other.