A TNF-α-CCL20-CCR6 axis regulates Nod1-induced B cell responses.

Innate immune responses provoke the accumulation of leukocytes at sites of inflammation. In addition to monocytes and granulocytes, B cells also participate in antimicrobial innate immune responses; however, the mechanisms for accumulation of B cells to sites of inflammation are not well understood. To study B cell accumulation following systemic inflammation, we used a model synthetic ligand that stimulates a specific pattern recognition molecule, nucleotide-binding oligomerization domain-containing protein 1 (Nod1).

Differential requirement of MALT1 for BAFF-induced outcomes in B cell subsets.

B cell activation factor of the TNF family (BAFF) activates noncanonical nuclear factor kappaB (NF-kappaB) heterodimers that promote B cell survival. We show that although MALT1 is largely dispensable for canonical NF-kappaB signaling downstream of the B cell receptor, the absence of MALT1 results in impaired BAFF-induced phosphorylation of NF-kappaB2 (p100), p100 degradation, and RelB nuclear translocation in B220(+) B cells. This corresponds with impaired survival of MALT1(-/-) marginal zone (MZ) but not follicular B cells in response to BAFF stimulation in vitro.

Targeted deletion of fgl2 leads to impaired regulatory T cell activity and development of autoimmune glomerulonephritis.

Mice with targeted deletion of fibrinogen-like protein 2 (fgl2) spontaneously developed autoimmune glomerulonephritis with increasing age, as did wild-type recipients reconstituted with fgl2-/- bone marrow. These data implicate FGL2 as an important immunoregulatory molecule and led us to identify the underlying mechanisms. Deficiency of FGL2, produced by CD4+CD25+ regulatory T cells (Treg), resulted in increased T cell proliferation to lectins and alloantigens, Th 1 polarization, and increased numbers of Ab-producing B cells following immunization with T-independent Ags.