Autoantibodies inhibit Plasmodium falciparum growth and are associated with protection from clinical malaria.

Many infections, including malaria, are associated with an increase in autoantibodies (AAbs). Prior studies have reported an association between genetic markers of susceptibility to autoimmune disease and resistance to malaria, but the underlying mechanisms are unclear. Here, we performed a longitudinal study of children and adults (n = 602) in Mali and found that high levels of plasma AAbs before the malaria season independently predicted a reduced risk of clinical malaria in children during the ensuing malaria season.

MAVS Positively Regulates Mitochondrial Integrity and Metabolic Fitness in B Cells.

Activated B cells experience metabolic changes that require mitochondrial remodeling, in a process incompletely defined. In this study, we report that mitochondrial antiviral signaling protein (MAVS) is involved in BCR-initiated cellular proliferation and prolonged survival. MAVS is well known as a mitochondrial-tethered signaling adaptor with a central role in viral RNA-sensing pathways that induce type I IFN.

curtails autoimmune nephritis via lasting bone marrow alterations, independent of hemozoin accumulation.

The host response against infection with commonly raises self-reactivity as a side effect, and antibody deposition in kidney has been cited as a possible cause of kidney injury during severe malaria. In contrast, animal models show that infection with the parasite confers long-term protection from lethal lupus nephritis initiated by autoantibody deposition in kidney. We have limited knowledge of the factors that make parasite infection more likely to induce kidney damage in humans, or the mechanisms underlying protection from autoimmune nephritis in animal models.

CCL17-producing cDC2s are essential in end-stage lupus nephritis and averted by a parasitic infection.

Lupus nephritis is a severe organ manifestation in systemic lupus erythematosus leading to kidney failure in a subset of patients. In lupus-prone mice, controlled infection with Plasmodium parasites protects against the progression of autoimmune pathology including lethal glomerulonephritis. Here, we demonstrate that parasite-induced protection was not due to a systemic effect of infection on autoimmunity as previously assumed, but rather to specific alterations in immune cell infiltrates into kidneys and renal draining lymph nodes.

Aberrant antibody affinity selection in SHIP-deficient B cells.

The strength of the Ag receptor signal influences development and negative selection of B cells, and it might also affect B-cell survival and selection in the GC. Here, we have used mice with B-cell-specific deletion of the 5'-inositol phosphatase SHIP as a model to study affinity selection in cells that are hyperresponsive to Ag and cytokine receptor stimulation. In the absence of SHIP, B cells have lower thresholds for Ag- and interferon (IFN)-induced activation, resulting in augmented negative selection in the BM and enhanced B-cell maturation in the periphery.

Grb2 functions at the top of the T-cell antigen receptor-induced tyrosine kinase cascade to control thymic selection.

Grb2 is an adaptor molecule that mediates Ras-MAPK activation induced by various receptors. Here we show that conditional ablation of Grb2 in thymocytes severely impairs both thymic positive and negative selections. Strikingly, the mutation attenuates T-cell antigen receptor (TCR) proximal signaling, including tyrosine phosphorylation of multiple signaling proteins and Ca(2+) influx.

A lupus-suppressor BALB/c locus restricts IgG2 autoantibodies without altering intrinsic B cell-tolerance mechanisms.

FcgammaR2B-deficient mice develop autoantibodies and glomerulonephritis with a pathology closely resembling human lupus when on the C57BL/6 (B6) background. The same mutation on the BALB/c background does not lead to spontaneous disease, suggesting differences in lupus susceptibility between the BALB/c and B6 strains. An F2 genetic analysis from a B6/BALB cross identified regions from the B6 chromosomes 12 and 17 with positive linkage for IgG autoantibodies.

T cell-specific deletion of the inositol phosphatase SHIP reveals its role in regulating Th1/Th2 and cytotoxic responses.

The 5'-phosphoinositol phosphatase SHIP negatively regulates signaling pathways triggered by antigen, cytokine and Fc receptors in both lymphocytes and myeloid cells. Mice with germ-line (null) deletion of SHIP develop a myeloproliferative-like syndrome that causes early lethality. Lymphocyte anomalies have been observed in SHIP-null mice, but it is unclear whether they are due to an intrinsic requirement of SHIP in these cells or a consequence of the severe myeloid pathology.

Establishment of the major compatibility complex-dependent development of CD4+ and CD8+ T cells by the Cbl family proteins.

Casitas B cell lymphoma (Cbl) proteins are negative regulators for T cell antigen receptor (TCR) signaling. Their role in thymocyte development remains unclear. Here we show that simultaneous inactivation of c-Cbl and Cbl-b in thymocytes enhanced thymic negative selection and altered the ratio of CD4(+) and CD8(+) T cells.

c-Cbl and Cbl-b regulate T cell responsiveness by promoting ligand-induced TCR down-modulation.

How Cbl family proteins regulate T cell responses is unclear. We found that c-Cbl Cbl-b double knock-out (dKO) T cells became hyperresponsive upon anti-CD3 stimulation, even though the major T cell antigen receptor (TCR) signaling pathways were not enhanced. The dKO T cells did not down-modulate surface TCR after ligand engagement, which resulted in sustained TCR signaling.