Our findings broaden the scope of phenotypes caused by mutations in NFKB1 and suggest that a subset of autoinflammatory diseases, such as Behçet disease, can be caused by rare monogenic variants in genes of the NF-κB pathway.

The pleiotropic cytokine, Interleukin 21 (IL21) is implicated in the pathogenesis of human systemic lupus erythematosus (SLE) by polymorphisms in the molecule and its receptor (IL21R). The SLE-like autoimmune disease of BXSB.Yaa mice is critically dependent on IL21 signaling, providing a model for understanding IL21/IL21R signaling in lupus pathogenesis. Here, we generated BXSB.Yaa mice selectively deficient in IL21R on B cells, on all T cells or on CD8+ T cells alone and examined the effects on disease. We found that IL21 signaling to B cells is essential for the development of all classical disease manifestations, but that IL21 signaling also supports the expansion of central memory, CD8+ suppressor cells and broadly represses the cytokine activity of CD4+ T cells. These results indicate that IL21 has both disease-promoting and disease-suppressive effects in the autoimmune disease of BXSB.Yaa mice.

Random recombination of antibody heavy-and light-chain genes results in a diverse B-cell receptor (BCR) repertoire including self-reactive BCRs. However, tolerance mechanisms that prevent the development of self-reactive B cells remain incompletely understood. The absence of the surrogate light chain, which assembles with antibody heavy chain forming a pre-BCR, leads to production of antinuclear antibodies (ANAs). Here we show that the naive follicular B-cell pool is enriched for cells expressing prototypic ANA heavy chains in these mice in a non-autoimmune background with a broad antibody repertoire. This results in the spontaneous formation of T-cell-dependent germinal centres that are enriched with B cells expressing prototypic ANA heavy chains. However, peripheral tolerance appears maintained by selection thresholds on cells entering the memory B-cell and plasma cell pools, as exemplified by the exclusion of cells expressing the intrinsically self-reactive V H 81X from both pools.

Cellular transformation is the first step in cancer development. Two features of cellular transformation are proliferation in reduced serum and loss of contact inhibition. Electronic Cell-Substrate Impedance Sensing (ECIS) measurements have been used to measure cellular proliferation, cytotoxicity, apoptosis, and attachment. We have used impedance measurements to distinguish normal cells from cells transformed with a constitutively active chemokine receptor, CXCR2. CXCR2, a member of the G-protein coupled receptor (GPCR) family, is normally involved in cellular activation and migration, but a single amino acid substitution leads to constitutive activity. NIH3T3 cells were transformed with a constitutively active CXCR2 (D143V_CXCR2) and growth in reduced serum and foci formation were measured using established biological assays and compared to data from ECIS. The results of this study show that impedance measurements provide a quick and reliable way of measuring cellular transformation and provide real time assessment of transformed cellular parameters. Use of the ECIS system could allow a rapid screening of anti-cancer drugs that alter cellular transformation.

IL6 is a multifunctional cytokine that drives terminal B cell differentiation and secretion of immunoglobulins. IL6 also cooperates with IL21 to promote differentiation of CD4+ T follicular helper cells (TFH). Elevated serum levels of IL6 correlate with disease flares in patients with systemic lupus erythematosus (SLE). We previously reported that IL21 produced by TFH plays a critical role in the development of the SLE-like disease of BXSB.Yaa mice. To examine the possible contributions of IL6 to disease, we compared disease parameters in IL6-deficient and IL6-competent BXSB.Yaa mice. We report that survival of IL6-deficient BXSB.Yaa mice was significantly prolonged in association with significant reductions in a variety of autoimmune manifestations. Moreover, B cells stimulated by co-engagement of TLR7 and B cell receptor (BCR) produced high levels of IL6 that was further augmented by stimulation with Type I interferon (IFN1). Importantly, the frequencies of TFH and serum levels of IL21 were significantly reduced in IL6-deficient mice. These findings suggest that high-level production of IL6 by B cells induced by integrated signaling from the IFN1 receptor, TLR7 and BCR promotes the differentiation of IL21-secreting TFH in a signaling sequence that drives the lethal autoimmune disease of BXSB.Yaa mice.