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Although all multicellular organisms have germ line–encoded innate receptors to sense pathogen-associated molecular patterns, vertebrates also evolved adaptive immunity based on somatically generated antigen receptors on B and T cells. Because randomly generated antigen receptors may also react with self-antigens, tolerance checkpoints operate to limit but not completely prevent autoimmunity. These two systems are intricately linked, with innate immunity playing an instrumental role in the induction of adaptive antiviral immunity. In this work, we review how inborn errors of innate immunity can instigate B cell autoimmunity. Increased nucleic acid sensing, often resulting from defects in metabolizing pathways or retroelement control, can break B cell tolerance and converge into TLR7-, cGAS-STING–, or MAVS-dominant signaling pathways. The resulting syndromes span a spectrum that ranges from chilblain and systemic lupus to severe interferonopathies.

As chronic antigenic stimulation from infection and autoimmunity is a feature of primary antibody deficiency (PAD), analysis of affected patients could yield insights into T-cell differentiation and explain how environmental exposures modify clinical phenotypes conferred by single-gene defects. CD57 marks dysfunctional T cells that have differentiated after antigenic stimulation. Indeed, while circulating CD57+ CD4+ T cells are normally rare, we found that they are increased in patients with PAD and markedly increased with CTLA4 haploinsufficiency or blockade. We performed single-cell RNA-seq analysis of matched CD57+ CD4+ T cells from blood and tonsil samples. Circulating CD57+ CD4+ T cells (CD4cyt) exhibited a cytotoxic transcriptome similar to that of CD8+ effector cells, could kill B cells, and inhibited B-cell responses. CTLA4 restrained the formation of CD4cyt. While CD57 also marked an abundant subset of follicular helper T cells, which is consistent with their antigen-driven differentiation, this subset had a pre-exhaustion transcriptomic signature marked by TCF7, TOX, and ID3 expression and constitutive expression of CTLA4 and did not become cytotoxic even after CTLA4 inhibition. Thus, CD57+ CD4+ T-cell cytotoxicity and exhaustion phenotypes are compartmentalised between blood and germinal centers. CTLA4 is a key modifier of CD4+ T-cell cytotoxicity, and the pathological CD4cyt phenotype is accentuated by infection.

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease, with a clear genetic component. While most SLE patients carry rare gene variants in lupus risk genes, little is known about their contribution to disease pathogenesis. Amongst them,SH2B3- a negative regulator of cytokine and growth factor receptor signaling – harbors rare coding variants in over 5% of SLE patients. Here we show that unlike the variant found exclusively in healthy controls, mostSH2B3rare variants found in lupus patients are predominantly hypomorphic alleles. Generation of two mouse lines carrying variants orthologous to those found in patients revealed SH2B3 is important to limit the numbers of immature and transitional B cells. Furthermore, hypomorphic SH2B3 was shown to impair negative selection of immature/transitional self-reactive B cells and accelerate autoimmunity in sensitized mice, at least in part due to increased IL-4R signaling and BAFF-R expression. This work identifies a previously unappreciated role forSH2B3in human B cell tolerance and lupus risk.SummaryZhanget al. reveal a role for hypomorphic SH2B3 in lupus risk. The study shows rare and damaging variants identified in lupus patients enable breach of B cell immune tolerance checkpoints and suggests involvement for dysregulated IL-4R signaling and BAFF-R expression.

Increased TLR7 signaling leading to type-I IFN production is an important contributor to human systemic lupus erythematosus (SLE). PACSIN1, a molecule that regulates synaptic vesicle recycling, has been linked to TLR7/9-mediated type I interferon production in mice, but the underlying mechanism is unknown. We undertook this study to explore pathogenicity and underlying mechanism of a de novo PACSIN1 missense variant identified in a child with SLE.PACSIN1 Q59K de novo and null variants were introduced into a human pDC cell line and mice by CRISPR/Cas9 editing. The effects of the variants on TLR7/9 signaling in human and mouse cells, as well as PACSIN1 mRNA and interferon signature in SLE patients, were assessed by real-time PCR and flow cytometry. Mechanisms were investigated by luciferase reporter assays, RNA interference, co- immunoprecipitation, and immunofluorescence.We established that PACSIN1 forms a trimolecular complex with TRAF4 and TRAF6 important for the regulation of type I-IFN. The Q59K mutation in PACSIN1 augments binding to N-WASP whilst it decreases binding to TRAF4, leading to unrestrained TRAF6-mediated activation of type-I IFN. Intriguingly, PACSIN1 Q59K increased TLR7 but not TLR9 signaling in human cells, leading to elevated IFN-β and interferon-inducible genes. Untreated SLE patients had high PACSIN1 expression in peripheral blood cells that correlated positively with interferon-related genes. Introduction of the Pacsin1 Q59K into mice caused increased surface TLR7 and Trail expression in B cells.PACSIN1 Q59K increases IFN-β activity via impairing TRAF4-mediated inhibition of TLR7 signaling, possibly contributing to SLE risk. This article is protected by copyright. All rights reserved.

Across the globe, 2-3% of humans carry thep.Ser132Prosingle nucleotide polymorphism inMLKL, the terminal effector protein of the inflammatory form of programmed cell death, necroptosis. We show that this substitution confers a gain in necroptotic function in human cells, with more rapid accumulation of activated MLKLS132Pin biological membranes and MLKLS132Poverriding pharmacological and endogenous inhibition of MLKL. In mouse cells, the equivalentMlkl S131Pmutation confers a gene dosage dependent reduction in sensitivity to TNF-induced necroptosis in both hematopoietic and non-hematopoietic cells, but enhanced sensitivity to IFN-β induced death in non-hematopoietic cells.In vivo,MlklS131Phomozygosity reduces the capacity to clearSalmonellafrom major organs and retards recovery of hematopoietic stem cells. Thus, by dysregulating necroptosis, the S131P substitution impairs the return to homeostasis after systemic challenge. Present day carriers of theMLKL S132Ppolymorphism may be the key to understanding how MLKL and necroptosis modulate the progression of complex polygenic human disease.

Some bacteria and parasites, such as Salmonella, actively disrupt germinal centers and elicit only low affinity antibodies, but the mechanisms by which microbes alter these responses is poorly understood. In this issue of Immunity, Biram et al. (2022) uncover a mechanism by which Salmonella recruits Sca-1

International audience; T follicular helper (Tfh) cells cognately guide differentiation of antigen-primed B cells in secondary lymphoid tissues. 'Tfh-like' populations not expressing the canonical Tfh cell transcription factor BCL6 have also been described, which can aid particular aspects of B cell differentiation. Tfh and Tfh-like cells are essential for protective and pathological humoral immunity. These CD4+ T cells that help B cells are polarized to produce diverse combinations of cytokines and chemokine receptors and can be grouped into distinct subsets that promote antibodies of different isotype, affinity, and duration, according to the nature of immune challenge. However, unified nomenclature to describe the distinct functional Tfh and Tfh-like cells does not exist. While explicitly acknowledging cellular plasticity, we propose categorizing these cell states into three groups based on phenotype and function, paired with their anatomical site of action.

Aims In 2003, an Australian woman was convicted by a jury of smothering and killing her four children over a 10-year period. Each child died suddenly and unexpectedly during a sleep period, at ages ranging from 19 days to 18 months. In 2019 we were asked to investigate if a genetic cause could explain the children’s deaths as part of an inquiry into the mother’s convictions. Methods and results Whole genomes or exomes of the mother and her four children were sequenced. Functional analysis of a novel CALM2 variant was performed by measuring Ca2+-binding affinity, interaction with calcium channels and channel function. We found two children had a novel calmodulin variant (CALM2 G114R) that was inherited maternally. Three genes (CALM1-3) encode identical calmodulin proteins. A variant in the corresponding residue of CALM3 (G114W) was recently reported in a child who died suddenly at age 4 and a sibling who suffered a cardiac arrest at age 5. We show that CALM2 G114R impairs calmodulin's ability to bind calcium and regulate two pivotal calcium channels (CaV1.2 and RyR2) involved in cardiac excitation contraction coupling. The deleterious effects of G114R are similar to those produced by G114W and N98S, which are considered arrhythmogenic and cause sudden cardiac death in children. Conclusion A novel functional calmodulin variant (G114R) predicted to cause idiopathic ventricular fibrillation, catecholaminergic polymorphic ventricular tachycardia, or mild long QT syndrome was present in two children. A fatal arrhythmic event may have been triggered by their intercurrent infections. Thus, calmodulinopathy emerges as a reasonable explanation for a natural cause of their deaths., Graphical Abstract

Expanded carrier screening (ECS) for recessive monogenic diseases requires prior knowledge of genomic variation, including DNA variants that cause disease. The composition of pathogenic variants differs greatly among human populations, but historically, research about monogenic diseases has focused mainly on people with European ancestry. By comparison, less is known about pathogenic DNA variants in people from other parts of the world. Consequently, inclusion of currently underrepresented Indigenous and other minority population groups in genomic research is essential to enable equitable outcomes in ECS and other areas of genomic medicine. Here, we discuss this issue in relation to the implementation of ECS in Australia, which is currently being evaluated as part of the national Government’s Genomics Health Futures Mission. We argue that significant effort is required to build an evidence base and genomic reference data so that ECS can bring significant clinical benefit for many Aboriginal and/or Torres Strait Islander Australians. These efforts are essential steps to achieving the Australian Government’s objectives and its commitment “to leveraging the benefits of genomics in the health system for all Australians.” They require culturally safe, community-led research and community involvement embedded within national health and medical genomics programs to ensure that new knowledge is integrated into medicine and health services in ways that address the specific and articulated cultural and health needs of Indigenous people. Until this occurs, people who do not have European ancestry are at risk of being, in relative terms, further disadvantaged.

MLKL is the essential effector of necroptosis, a form of programmed lytic cell death. We have isolated a mouse strain with a single missense mutation, MlklD139V, that alters the two-helix ‘brace’ that connects the killer four-helix bundle and regulatory pseudokinase domains. This confers constitutive, RIPK3 independent killing activity to MLKL. Homozygous mutant mice develop lethal postnatal inflammation of the salivary glands and mediastinum. The normal embryonic development of MlklD139V homozygotes until birth, and the absence of any overt phenotype in heterozygotes provides important in vivo precedent for the capacity of cells to clear activated MLKL. These observations offer an important insight into the potential disease-modulating roles of three common human MLKL polymorphisms that encode amino acid substitutions within or adjacent to the brace region. Compound heterozygosity of these variants is found at up to 12-fold the expected frequency in patients that suffer from a pediatric autoinflammatory disease, chronic recurrent multifocal osteomyelitis (CRMO)., Necroptosis is a regulated form of inflammatory cell death driven by activated MLKL. Here, the authors identify a mutation in the brace region that confers constitutive activation, leading to lethal inflammation in homozygous mutant mice and providing insight into human mutations in this region.

Follicular T cells including T follicular helper (T

Although circumstantial evidence supports enhanced Toll-like receptor 7 (TLR7) signalling as a mechanism of human systemic autoimmune disease1–7, evidence of lupus-causing TLR7 gene variants is lacking. Here we describe human systemic lupus erythematosus caused by a TLR7 gain-of-function variant. TLR7 is a sensor of viral RNA8,9 and binds to guanosine10–12. We identified a de novo, previously undescribed missense TLR7Y264H variant in a child with severe lupus and additional variants in other patients with lupus. The TLR7Y264H variant selectively increased sensing of guanosine and 2',3'-cGMP10–12, and was sufficient to cause lupus when introduced into mice. We show that enhanced TLR7 signalling drives aberrant survival of B cell receptor (BCR)-activated B cells, and in a cell-intrinsic manner, accumulation of CD11c+ age-associated B cells and germinal centre B cells. Follicular and extrafollicular helper T cells were also increased but these phenotypes were cell-extrinsic. Deficiency of MyD88 (an adaptor protein downstream of TLR7) rescued autoimmunity, aberrant B cell survival, and all cellular and serological phenotypes. Despite prominent spontaneous germinal-centre formation in Tlr7Y264H mice, autoimmunity was not ameliorated by germinal-centre deficiency, suggesting an extrafollicular origin of pathogenic B cells. We establish the importance of TLR7 and guanosine-containing self-ligands for human lupus pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.

Somatic mutations in P2RY8 that promote B cell growth and migration are common in lymphomas. He et al. describe germline loss-of-function P2RY8 variants in SLE and uncover novel functions of P2RY8 in immunological tolerance through restraining plasma cell development and promoting B cell–negative selection., B cell self-tolerance is maintained through multiple checkpoints, including restraints on intracellular signaling and cell trafficking. P2RY8 is a receptor with established roles in germinal center (GC) B cell migration inhibition and growth regulation. Somatic P2RY8 variants are common in GC-derived B cell lymphomas. Here, we identify germline novel or rare P2RY8 missense variants in lupus kindreds or the related antiphospholipid syndrome, including a “de novo” variant in a child with severe nephritis. All variants decreased protein expression, F-actin abundance, and GPCR-RhoA signaling, and those with stronger effects increased AKT and ERK activity and cell migration. Remarkably, P2RY8 was reduced in B cell subsets from some SLE patients lacking P2RY8 gene variants. Low P2RY8 correlated with lupus nephritis and increased age-associated B cells and plasma cells. By contrast, P2RY8 overexpression in cells and mice restrained plasma cell development and reinforced negative selection of DNA-reactive developing B cells. These findings uncover a role of P2RY8 in immunological tolerance and lupus pathogenesis., Graphical Abstract

During infections with protozoan parasites or some viruses, T cell immunosuppression is generated simultaneously with a high B cell activation. It has been described that, as well as producing antibodies, plasmablasts, the differentiation product of activated B cells, can condition the development of protective immunity in infections. Here, we show that, in T. cruzi infection, all the plasmablasts detected during the acute phase of the infection had higher surface expression of PD-L1 than other mononuclear cells. PD-L1hi plasmablasts were induced in vivo in a BCR-specific manner and required help from Bcl-6+CD4+T cells. PD-L1hi expression was not a characteristic of all antibody-secreting cells since plasma cells found during the chronic phase of infection expressed PD-L1 but at lower levels. PD-L1hi plasmablasts were also present in mice infected with Plasmodium or with lymphocytic choriomeningitis virus, but not in mice with autoimmune disorders or immunized with T cell-dependent antigens. In vitro experiments showed that PD-L1hi plasmablasts suppressed the T cell response, partially via PD-L1. Thus, this study reveals that extrafollicular PD-L1hi plasmablasts, whose peaks of response precede the peak of germinal center response, may have a modulatory function in infections, thus influencing T cell response.

Age-associated B cells (ABCs) accumulate after infection, during aging, and in systemic autoimmunity, contributing to pathogenesis in the latter1. To date, their precise ontogeny and whether they represent a B cell subset distinct from the other major effector subsets - plasma cells and memory B cells - remain unknown. We asked whether ABC formation requires the expression of a unique transcription factor. Here, we used single-cell RNA sequencing to identify differentially-expressed transcription factors shared by ABCs from both lupus patient and lupus-prone mice. Using an arrayed CRISPR screen, we show Zeb2 is essential for ABC differentiation in vitro. Selective deficiency of Zeb2 in B cells also leads to impaired ABC formation in vivo. Zeb2 drove ABC specification by directly binding the promoters of ABC signature genes including Itgax and Itgam encoding for CD11c and CD11b respectively. Zeb2 also targeted molecules involved in cytokine receptor signaling via the JAK/STAT pathway including Il21r and Socs5. Administration of the approved JAK/STAT inhibitor tofacitinib effectively ameliorated ABC accumulation in mice and patients with autoimmunity. This study reveals ABCs represent a distinct B cell subset dependent on Zeb2 expression, and provides a rationale for the use of JAK/STAT inhibitors to treat ABC-mediated autoimmune diseases.

Objective To compare the frequency of rare variants in genes of the pathophysiologically relevant endosomal Toll-like receptor (eTLR) pathway and any quantifiable differences in variant rarity, predicted deleteriousness, or molecular proximity in patients with systemic lupus erythematosus (SLE) and healthy controls. Patients and methods 65 genes associated with the eTLR pathway were identified by literature search and pathway analysis. Using next generation sequencing techniques, these were compared in two randomised cohorts of patients with SLE (n = 114 and n = 113) with 197 healthy controls. Genetically determined ethnicity was used to normalise minor allele frequencies (MAF) for the identified genetic variants and these were then compared by their frequency: rare (MAF 0.02). This was compared to the results for 65 randomly selected genes. Results Patients with SLE are more likely to carry a rare nonsynonymous variant affecting proteins within the eTLR pathway than healthy controls. Furthermore, individuals with SLE are more likely to have multiple rare variants in this pathway. There were no differences in rarity, Combined Annotation Dependent Depletion (CADD) score, or molecular proximity for rare eTLR pathway variants. Conclusions Rare non-synonymous variants are enriched in patients with SLE in the eTLR pathway. This supports the hypothesis that SLE arises from several rare variants of relatively large effect rather than many common variants of small effect.

The SH2B family of adaptor proteins, SH2-B, APS, and LNK are key modulators of cellular signalling pathways. Whilst SH2-B and APS have been partially structurally and biochemically characterised, to date there has been no such characterisation of LNK. Here we present two crystal structures of the LNK substrate recognition domain, the SH2 domain, bound to phosphorylated motifs from JAK2 and EPOR, and biochemically define the basis for target recognition. The LNK SH2 domain adopts a canonical SH2 domain fold with an additional N-terminal helix. Targeted analysis of binding to phosphosites in signalling pathways indicated that specificity is conferred by amino acids one- and three-residues downstream of the phosphotyrosine. Several mutations in LNK showed impaired target binding in vitro and a reduced ability to inhibit signalling, allowing an understanding of the molecular basis of LNK dysfunction in variants identified in patients with myeloproliferative disease., LNK is a potent negative regulator of cytokine signaling implicated in blood cells proliferation. Here the authors present structures of the substrate recognition (SH2) domain of LNK in complex with phosphorylated motifs from JAK2 and EPOR; providing insight into its binding specificity and mode of action.

Understanding which arms of the immune response are responsible for protection against SARS-CoV-2 infection is key to predicting long-term immunity and to inform vaccine design. Two studies in this issue of Cell collectively suggest that, although SARS-CoV-2 infection may blunt long-lived antibody responses, immune memory might still be achieved through virus-specific memory T cells.

Background Resistance to thyroid hormones is a very rare condition, which is often misdiagnosed and mistreated. The cases where there is a concomitant autoimmune thyroid disorder are ultra-rare and particularly challenging to treat. Diagnostic and research-based genomic testing can sometimes identify pathogenic variants unrelated to the primary reason for testing (incidental findings). Case presentation We present a patient with thyroid resistance associated with hypothyroid Hashimoto thyroiditis. The long diagnostic odyssey spanning over 20-years included repeated misdiagnoses and mistreatments and was concluded by a research-based genomic testing, identifying a “de novo” THRB pathogenic variant. The varying sensitivity of various tissues to thyroid hormones accompanied by hypothyroid Hashimoto thyroiditis continues to pose a significant treatment challenge. Conclusions Thyroid hormone resistance continues to be an un(der)- and misdiagnosed thyroid condition whose management is particularly challenging when associated with autoimmune thyroid disease. Whole exome sequencing has the potential to identify THRB pathogenic variants as incidental findings. Reporting such secondary findings from genomic testing may be particularly important in the context of the rarity of the condition and the potential clinical consequences of misdiagnosis and mistreatment.

While circumstantial evidence supports enhanced TLR7 signaling as a mechanism of human systemic autoimmune disease, we have lacked the proof afforded by lupus-causing TLR7 gene variants. Here we describe monogenic human systemic lupus erythematosus (SLE) caused by TLR7 gain-of-function. We identified a de novo, novel, missense TLR7 Y264H variant in a child with severe lupus and additional novel or rare variants in probands with interferonopathies or systemic autoimmunity (Aicardi Goutieres Sd, SLE, Sjogren’s Sd, and juvenile idiopathic arthritis). The variants increased NF-κB and IFN-β activity and the de novo TLR7 Y264H variant was sufficient to cause lupus when introduced in mice. We show that constitutive TLR7 signaling drives aberrant survival of BCR-activated B cells that would otherwise die, and accumulation of CD11c+ age-associated B cells and germinal center (GC) B cells in a B cell-intrinsic manner. Follicular and extrafollicular helper T-cells were also increased but these phenotypes were cell-extrinsic. MyD88-deficiency rescued autoimmunity, aberrant B cell survival, and all cellular and serological phenotypes. Despite prominent spontaneous GC formation in mice carrying the TLR7 Y264H variant, we show that TLR7-driven lupus was not ameliorated when the TLR7 Y264H mice were made GC-deficient suggesting extrafollicular origin of pathogenic B cells. We establish the importance of TLR7 for human SLE pathogenesis, which paves the way for therapeutic TLR7 or MyD88 inhibition.

JEM has been a launching pad for scientific careers since its inception. Here is a collection of testimonials attesting to the diversity of the scientific community it serves.

During infections with protozoan parasites or virus, T cell immunosuppression is generated simultaneously with a high B cell activation. Here, we show that in T. cruzi infection, all plasmablasts detected had higher surface expression of PD-L1, than other mononuclear cells. PD-L1hi plasmablasts were induced in vivo in an antigen-specific manner and required help from Bcl-6+CD4+T cells. PD-L1hi expression was not a characteristic of all antibody-secreting cells since plasma cells found during the chronic phase of infection express PD-L1 but at lower levels. PD-L1hi plasmablasts were also present in mice infected with Plasmodium or with lymphocytic choriomeningitis virus, but not in mice with autoimmune disorders or immunized with T cell-dependent antigens. PD-L1hi plasmablasts suppressed T cell response, via PD-L1, in vitro and in vivo. Thus, this study reveals that extrafollicular PD-L1hi plasmablasts, which precede the germinal center (CG) response, are a suppressive population in infections that may influence T cell response.Brief summaryPathogens develop different strategies to settle in the host. We identified a plasmablats population induced by pathogens in acute infections which suppress T cell response.

Autoimmune disease is a substantial cause of morbidity and is strongly influenced by genetic risk. Extensive efforts have characterized the overall genetic basis of many autoimmune diseases, typically by investigation of common variants. While these common variants have modest effects and may cumulatively predispose to disease, it is also increasingly apparent that rare variants have significantly greater effect on phenotype and are likely to contribute to autoimmune disease. Recent advances have illustrated the next fundamental step in elucidating the genetic basis of autoimmunity, moving beyond association to demonstrate the functional consequences of these variants.

Genetic mutations account for many devastating early onset immune deficiencies. In contrast, less severe and later onset immune diseases, including in patients with no prior family history, remain poorly understood. Whole exome sequencing in two cohorts of such patients identified a novel heterozygous de novo IKBKB missense mutation (c.607G>A) in two separate kindreds in whom probands presented with immune dysregulation, combined T and B cell deficiency, inflammation, and epithelial defects. IKBKB encodes IKK2, which activates NF-κB signaling. IKK2V203I results in enhanced NF-κB signaling, as well as T and B cell functional defects. IKK2V203 is a highly conserved residue, and to prove causation, we generated an accurate mouse model by introducing the precise orthologous codon change in Ikbkb using CRISPR/Cas9. Mice and humans carrying this missense mutation exhibit remarkably similar cellular and biochemical phenotypes. Accurate mouse models engineered by CRISPR/Cas9 can help characterize novel syndromes arising from de novo germline mutations and yield insight into pathogenesis.

Kara et al. show that ACKR4 regulates early activated B cell differentiation fate. ACKR4 limits the early proliferation of activated B cells by restricting their initial access to the splenic interfollicular zone., Activated B cells can initially differentiate into three functionally distinct fates—early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells—by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell–intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate.

Summary We identify an intronic deletion in VANGL1 that predisposes to renal injury in high risk populations through a kidney-intrinsic process. Half of all SLE patients develop nephritis, yet the predisposing mechanisms to kidney damage remain poorly understood. There is limited evidence of genetic contribution to specific organ involvement in SLE.1,2 We identify a large deletion in intron 7 of Van Gogh Like 1 (VANGL1), which associates with nephritis in SLE patients. The same deletion occurs at increased frequency in an indigenous population (Tiwi Islanders) with 10-fold higher rates of kidney disease compared with non-indigenous populations. Vangl1 hemizygosity in mice results in spontaneous IgA and IgG deposition within the glomerular mesangium in the absence of autoimmune nephritis. Serum transfer into B cell-deficient Vangl1+/− mice results in mesangial IgG deposition indicating that Ig deposits occur in a kidney-intrinsic fashion in the absence of Vangl1. These results suggest that Vangl1 acts in the kidney to prevent Ig deposits and its deficiency may trigger nephritis in individuals with SLE., Graphical abstract, Highlights • Intronic deletions in VANGL1 are associated with risks of glomerulonephritis in SLE • Vangl1+/− mice develop spontaneous deposition of immunoglobulin in glomeruli • Vangl1+/− mice do not develop glomerulonephritis despite antibody deposition • Immunoglobulin deposition in Vangl1+/− occurs in a kidney-intrinsic manner, The organ specificity risks of lupus nephritis are unclear. Jiang et al. identify a common intronic deletion in VANGL1 that increases risks of nephritis in SLE patients. Vangl1+/− mice develop spontaneous deposition of immunoglobulin in the kidney without glomerulonephritis in a kidney intrinsic manner.

Damaging inflammation is a hallmark of Mycobacterium tuberculosis infection, and understanding how this is regulated is important for the development of new therapies to limit excessive inflammation. The E3 ubiquitin ligase, Roquin, is involved in immune regulation; however, its role in immunity to M. tuberculosis is unknown. To address this, we infected mice with a point mutation in Roquin1/Rc3h1 (sanroque). Aerosol-infected sanroque mice showed enhanced control of M. tuberculosis infection associated with delayed bacterial dissemination and upregulated TNF production in the lungs after 2 wk. However, this early control of infection was not maintained, and by 8 wk postinfection sanroque mice demonstrated an increased bacterial burden and dysregulated inflammation in the lungs. As the inflammation in the lungs of the sanroque mice could have been influenced by emerging autoimmune conditions that are characteristic of the mice aging, the function of Roquin was examined in immune cell subsets in the absence of autoimmune complications. M. bovis bacillus Calmette–Guérin-primed sanroque T cells transferred into Rag1−/− mice provided equivalent protection in the spleen and liver. Interestingly, the transfer of mycobacteria-specific (P25 CD4+ TCR transgenic) wild-type spleen cells into sanroque.Rag1−/− mice actually led to enhanced protection with reduced bacterial load, decreased chemokine expression, and reduced inflammation in the lungs compared with transfers into Rag1−/− mice expressing intact Roquin. These studies suggest that modulation of Roquin in myeloid cells may reduce both inflammation and bacterial growth during the chronic phase of M. tuberculosis infection.

Protective high-affinity antibody responses depend on competitive selection of B cells carrying somatically mutated B-cell receptors by follicular helper T (T FH ) cells in germinal centres. The rapid T-B-cell interactions that occur during this process are reminiscent of neural synaptic transmission pathways. Here we show that a proportion of human T FH cells contain dense-core granules marked by chromogranin B, which are normally found in neuronal presynaptic terminals storing catecholamines such as dopamine. T FH cells produce high amounts of dopamine and release it upon cognate interaction with B cells. Dopamine causes rapid translocation of intracellular ICOSL (inducible T-cell co-stimulator ligand, also known as ICOSLG) to the B-cell surface, which enhances accumulation of CD40L and chromogranin B granules at the human T FH cell synapse and increases the synapse area. Mathematical modelling suggests that faster dopamine-induced T-B-cell interactions increase total germinal centre output and accelerate it by days. Delivery of neurotransmitters across the T-B-cell synapse may be advantageous in the face of infection. Refereed/Peer-reviewed

Generation of broadly neutralizing antibodies is a key aim of HIV vaccine design, but the precursor B cells are rare. Abbott et al. (2018) report that high affinity and avidity immunogens are required to promote maturation of low frequency B cells in germinal centers.

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Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease. It is thought that many common variant gene loci of weak effect act additively to predispose to common autoimmune diseases, while the contribution of rare variants remains unclear. Here we describe that rare coding variants in lupus-risk genes are present in most SLE patients and healthy controls. We demonstrate the functional consequences of rare and low frequency missense variants in the interacting proteins BLK and BANK1, which are present alone, or in combination, in a substantial proportion of lupus patients. The rare variants found in patients, but not those found exclusively in controls, impair suppression of IRF5 and type-I IFN in human B cell lines and increase pathogenic lymphocytes in lupus-prone mice. Thus, rare gene variants are common in SLE and likely contribute to genetic risk.

SUMMARYWe have isolated a mouse strain with a single missense mutation in the gene encoding MLKL, the essential effector of necroptotic cell death. The resulting substitution lies within the two-helix ‘brace’ and confers constitutive, RIPK3 independent, killing activity to MLKL. Mice homozygous forMlklD139Vdevelop lethal inflammation within days of birth, implicating the salivary glands and pericardium as hotspots for necroptosis and inflammatory infiltration. The normal development ofMlklD139Vhomozygotes until birth, and the absence of any overt phenotype in heterozygotes provides importantin vivoprecedent for the capacity of cells to clear activated MLKL. These observations offer an important insight into the potential disease-modulating roles of three common humanMLKLpolymorphisms that encode amino acid substitutions within or adjacent to the brace region. Compound heterozygosity of these variants is found at up to 12-fold the expected frequency in patients that suffer from a pediatric autoinflammatory disease, CRMO.