Antibodies generated against conserved antigens expressed by bacteria and allergen-bearing fungi suppress airway disease.

There has been a sharp rise in allergic asthma and asthma-related deaths in the developed world, in contrast to many childhood illnesses that have been reduced or eliminated. The hygiene hypothesis proposes that excessively sanitary conditions early in life result in autoimmune and allergic phenomena because of a failure of the immune system to receive proper microbial stimulation during development. We demonstrate that Abs generated against conserved bacterial polysaccharides are reactive with and dampen the immune response against chitin and Aspergillus fumigatus. A reduction in Ag uptake, cell influx, cell activation, and cytokine production occurred in the presence of anti-polysaccharide Abs, resulting in a striking decrease in the severity of allergic airway disease in mice. Overall, our results suggest that Ag exposure--derived from environmental sources, self-antigens, or vaccination--during the neonatal period has dramatic effects on the adult Ab response and modifies the development of allergic airway disease.

Mutations in Traf3ip1 reveal defects in ciliogenesis, embryonic development, and altered cell size regulation.

Tumor necrosis factor alpha receptor 3 interacting protein 1 (Traf3ip1), also known as MIPT3, was initially characterized through its interactions with tubulin, actin, TNFR-associated factor-3 (Traf3), IL-13R1, and DISC1. It functions as an inhibitor of IL-13-mediated phosphorylation of Stat6 and in sequestration of Traf3 and DISC1 to the cytoskeleton. Studies of the Traf3ip1 homologs in C. elegans (DYF-11), Zebrafish (elipsa), and Chlamydomonas (IFT54) revealed that the protein localizes to the cilium and is required for ciliogenesis. Similar localization data has now been reported for mammalian Traf3ip1. This raises the possibility that Traf3ip1 has an evolutionarily conserved role in mammalian ciliogenesis in addition to its previously indicated functions. To evaluate this possibility, a Traf3ip1 mutant mouse line was generated. Traf3ip1 mutant cells are unable to form cilia. Homozygous Traf3ip1 mutant mice are not viable and have both neural developmental defects and polydactyly, phenotypes typical of mouse mutants with ciliary assembly defects. Furthermore, in Traf3ip1 mutants the hedgehog pathway is disrupted, as evidenced by abnormal dorsal-ventral neural tube patterning and diminished expression of a hedgehog reporter. Analysis of the canonical Wnt pathway indicates that it was largely unaffected; however, specific domains in the pharyngeal arches have elevated levels of reporter activity. Interestingly, Traf3ip1 mutant embryos and cells failed to show alterations in IL-13 signaling, one of the pathways associated with its initial discovery. Novel phenotypes observed in Traf3ip1 mutant cells include elevated cytosolic levels of acetylated microtubules and a marked increase in cell size in culture. The enlarged Traf3ip1 mutant cell size was associated with elevated basal mTor pathway activity. Taken together, these data demonstrate that Traf3ip1 function is highly conserved in ciliogenesis and is important for proper regulation of a number of essential developmental and cellular pathways. The Traf3ip1 mutant mouse and cell lines will provide valuable resources to assess cilia function in mammalian development and also serve as a tool to explore the potential connections between cilia and cytoskeletal dynamics, mTor regulation, and cell volume control.

Cathelin-related antimicrobial peptide differentially regulates T- and B-cell function.

Mammalian antimicrobial peptides (AMPs) play an important role in host defense via direct antimicrobial activity as well as immune regulation. The mouse cathelin-related antimicrobial peptide (mCRAMP), produced from the mouse gene Camp, is the only mouse cathelicidin identified and the ortholog of the human gene encoding the peptide LL-37. This study tested the hypothesis that mouse B and T cells produce and respond to mCRAMP. We show that all mature mouse B-cell subsets, including follicular (FO), marginal zone (MZ), B1a, and B1b cells, as well as CD4(+) and CD8(+) T cells produce Camp mRNA and mCRAMP protein. Camp(-/-) B cells produced equivalent levels of IgM, IgG3, and IgG2c but less IgG1 and IgE, while Camp(-/-) CD4(+) T cells cultured in Th2-inducing conditions produced more IL-4-expressing cells when compared with WT cells, effects that were reversed upon addition of mCRAMP. In vivo, Camp(-/-) mice immunized with TNP-OVA absorbed in alum produced an enhanced TNP-specific IgG1 response when compared with WT mice. ELISpot analysis revealed increased numbers of TNP-specific IgG1-secreting splenic B cells and FACS analysis revealed increased CD4(+) T-cell IL-4 expression. Our results suggest that mCRAMP differentially regulates B- and T-cell function and implicate mCRAMP in the regulation of adaptive immune responses.

DNA microarray gene expression profile of marginal zone versus follicular B cells and idiotype positive marginal zone B cells before and after immunization with Streptococcus pneumoniae.

Marginal zone (MZ) B cells play an important role in the clearance of blood-borne bacterial infections via rapid T-independent IgM responses. We have previously demonstrated that MZ B cells respond rapidly and robustly to bacterial particulates. To determine the MZ-specific genes that are expressed to allow for this response, MZ and follicular (FO) B cells were sort purified and analyzed via DNA microarray analysis. We identified 181 genes that were significantly different between the two B cell populations. Ninety-nine genes were more highly expressed in MZ B cells while 82 genes were more highly expressed in FO B cells. To further understand the molecular mechanisms by which MZ B cells respond so rapidly to bacterial challenge, Id-positive and -negative MZ B cells were sort purified before (0 h) or after (1 h) i.v. immunization with heat-killed Streptococcus pneumoniae, R36A, and analyzed via DNA microarray analysis. We identified genes specifically up-regulated or down-regulated at 1 h following immunization in the Id-positive MZ B cells. These results give insight into the gene expression pattern in resting MZ vs FO B cells and the specific regulation of gene expression in Ag-specific MZ B cells following interaction with Ag.

CD86 regulates IgG1 production via a CD19-dependent mechanism.

CD86 signals directly in a B cell to activate PI3K and increase the rate of IgG(1) production, without affecting germline transcription. However, the mechanism by which CD86 activates PI3K in a B cell and the relevance of CD86 stimulation in vivo remains unknown. We show that the addition of CD28/Ig to CD40 ligand/IL-4-activated wild-type, but not CD86- or CD19-deficient, B cells increased the level of phosphorylation for Lyn and CD19, as well as the amount of Lyn, Vav, and PI3K that immunoprecipitated with CD19. Adoptive transfer of CD86-deficient B cells and wild-type CD4(+) T cells into RAG2-deficient mice and immunization with trinitrophenylated keyhole limpet hemocyanin resulted in an IL-4 and germline IgG(1) response equivalent to control mice, but a decrease in serum IgG(1). Thus, our findings suggest that CD86 plays a key role in regulating the level of IgG(1) produced in vitro and in vivo, and that Lyn and CD19 may be the signaling intermediates activated by CD86 proximal to PI3K.

CD86 stimulation on a B cell activates the phosphatidylinositol 3-kinase/Akt and phospholipase C gamma 2/protein kinase C alpha beta signaling pathways.

Stimulation of CD86 on a CD40L/IL-4-activated murine B cell increases the rate of mature IgG1 transcription by increasing the level of NF-kappaB activation, as well as Oct-2 expression and binding to the 3'-IgH enhancer. The signal transduction pathway activated by CD86 proximal to NF-kappaB activation is unknown. In this study, we show that CD86 stimulation on an activated B cell increases the activity of PI3K and the phosphorylation of phosphoinositide-dependent kinase 1, Akt, and IkappaB kinase alphabeta. In addition, CD86 stimulation induces an increase in the phosphorylation of phospholipase Cgamma2 and protein kinase C alphabeta. CD86-mediated activation of these two signaling pathways leads to increased Oct-2 expression, increased gene activity mediated by NF-kappaB and 3'-IgH enhancer increased activity. These results identify a previously unknown signaling pathway induced by CD86 to regulate the level of B cell gene expression and activity.

It takes nerve to tell T and B cells what to do.

The existence of an association between the brain and immunity has been documented. Data show that the nervous and immune systems communicate with one another to maintain immune homeostasis. Activated immune cells secrete cytokines that influence central nervous system activity, which in turn, activates output through the peripheral nervous system to regulate the level of immune cell activity and the subsequent magnitude of an immune response. In this review, we will focus our presentation and discussion on the findings that indicate a regulatory role for the peripheral sympathetic nervous system in modulating the level of cytokine and antibody produced during an immune response. Data will be discussed from studies involving the stimulation of the beta2 adrenergic receptor expressed on CD4+ T cells and B cells by norepinephrine or selective agonists. We will also discuss how dysregulation of this line of communication between the nervous and immune systems might contribute to disease development and progression.

CD86 and beta2-adrenergic receptor signaling pathways, respectively, increase Oct-2 and OCA-B Expression and binding to the 3'-IgH enhancer in B cells.

Stimulation of CD86 (formerly known as B7-2) and/or the beta2-adrenergic receptor on a CD40 ligand/interleukin-4-activated B cell increased the rate of mature IgG1 transcription. To identify the mechanism responsible for this effect, we determined whether CD86 and/or beta2-adrenergic receptor stimulation regulated transcription factor expression and binding to the 3'-IgH enhancer in vitro and in vivo. We showed that CD86 stimulation increased the nuclear localization of NF-kappaB1 (p50) and phosphorylated RelA (p65) and increased Oct-2 expression and binding to the 3'-IgH enhancer, in a protein kinase C-dependent manner. These effects were lost when CD86-deficient or NF-kappaB1-deficient B cells were used. CD86 stimulation also increased the level of IkappaB-alpha phosphorylation but in a protein kinase C-independent manner. Beta2-adrenergic receptor stimulation increased CREB phosphorylation, OCA-B expression, and OCA-B binding to the 3'-IgH enhancer in a protein kinase A-dependent manner, an effect lost when beta2-adrenergic receptor-deficient B cells were used. Also, the beta2-adrenergic receptor-induced increase in the level of mature IgG1 transcript was lost when OCA-B-deficient B cells were used. These data are the first to show that CD86 stimulation up-regulates the expression of the transcription factor Oct-2 in a protein kinase C- and NF-kappaB1-dependent manner, and that beta2-adrenergic receptor stimulation up-regulates the expression of the coactivator OCA-B in a protein kinase A-dependent manner to cooperate with Oct-2 binding to the 3'-IgH enhancer.