Publications by authors named "Fabienne Mackay"

104 Publications

B-cells expressing NgR1 and NgR3 are localized to EAE-induced inflammatory infiltrates and are stimulated by BAFF.

Sci Rep 2021 Feb 3;11(1):2890. Epub 2021 Feb 3.

Department of Neuroscience, Central Clinical School, Monash University, Prahran, VIC, 3004, Australia.

We have previously reported evidence that Nogo-A activation of Nogo-receptor 1 (NgR1) can drive axonal dystrophy during the neurological progression of experimental autoimmune encephalomyelitis (EAE). However, the B-cell activating factor (BAFF/BlyS) may also be an important ligand of NgR during neuroinflammation. In the current study we define that NgR1 and its homologs may contribute to immune cell signaling during EAE. Meningeal B-cells expressing NgR1 and NgR3 were identified within the lumbosacral spinal cords of ngr1 EAE-induced mice at clinical score 1. Furthermore, increased secretion of immunoglobulins that bound to central nervous system myelin were shown to be generated from isolated NgR1- and NgR3-expressing B-cells of ngr1 EAE-induced mice. In vitro BAFF stimulation of NgR1- and NgR3-expressing B cells, directed them into the cell cycle DNA synthesis phase. However, when we antagonized BAFF signaling by co-incubation with recombinant BAFF-R, NgR1-Fc, or NgR3 peptides, the B cells remained in the G0/G1 phase. The data suggest that B cells express NgR1 and NgR3 during EAE, being localized to infiltrates of the meninges and that their regulation is governed by BAFF signaling.
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http://dx.doi.org/10.1038/s41598-021-82346-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7858582PMC
February 2021

Chemokine receptor CXCR7 non-cell-autonomously controls pontine neuronal migration and nucleus formation.

Sci Rep 2020 07 16;10(1):11830. Epub 2020 Jul 16.

Graduate School of Frontier Biosciences, Osaka University, Yamadaoka 1-3, Suita, Osaka, 565-0871, Japan.

Long distance tangential migration transports neurons from their birth places to distant destinations to be incorporated into neuronal circuits. How neuronal migration is guided during these long journeys is still not fully understood. We address this issue by studying the migration of pontine nucleus (PN) neurons in the mouse hindbrain. PN neurons migrate from the lower rhombic lip first anteriorly and then turn ventrally near the trigeminal ganglion root towards the anterior ventral hindbrain. Previously we showed that in mouse depleted of chemokine receptor CXCR4 or its ligand CXCL12, PN neurons make their anterior-to-ventral turn at posteriorized positions. However, the mechanism that spatiotemporally controls the anterior-to-ventral turning is still unclear. Furthermore, the role of CXCR7, the atypical receptor of CXCL12, in pontine migration has yet to be examined. Here, we find that the PN is elongated in Cxcr7 knockout due to a broadened anterior-to-ventral turning positions. Cxcr7 is not expressed in migrating PN neurons en route to their destinations, but is strongly expressed in the pial meninges. Neuroepithelium-specific knockout of Cxcr7 does not recapitulate the PN phenotype in Cxcr7 knockout, suggesting that CXCR7 acts non-cell-autonomously possibly from the pial meninges. We show further that CXCR7 regulates pontine migration by modulating CXCL12 protein levels.
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http://dx.doi.org/10.1038/s41598-020-68852-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7367352PMC
July 2020

Associations of serum soluble Fas and Fas ligand (FasL) with outcomes in systemic lupus erythematosus.

Lupus Sci Med 2020 06;7(1)

Centre for Inflammatory Diseases, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia

Objective: Fas/Fas ligand (FasL) and B cell-activating factor (BAFF) signalling have pivotal roles in SLE pathogenesis. We investigated the clinical associations of serum concentrations of soluble Fas (sFas) and soluble FasL (sFasL) in SLE and their relationship with BAFF.

Methods: Serum sFas and sFasL were quantified by multiplex assay, and BAFF by ELISA, in 118 patients with SLE and 17 healthy controls (HC). SLE disease activity and organ damage were assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) and the Systemic Lupus International Collaborating Clinics Damage Index.

Results: sFas, sFasL and BAFF were detectable in all samples. Serum sFas and sFasL were significantly higher in SLE compared with HC. In univariable regression analyses, patients with active renal disease and those with flare had significantly higher levels of sFas compared with those without. High serum BAFF in patients with SLE was associated with increased sFas but not sFasL. The association between sFas and renal disease remained significant after adjusting for BAFF, but the association with flare attenuated. High sFas levels were associated with increased time-adjusted mean SLEDAI-2K, even after adjusting for BAFF, and with higher odds of flare over time. In contrast, high sFasL was associated with reduced organ damage over time. Serum sFasL/sFas ratio was negatively associated with active overall disease, flare and organ damage.

Conclusions: Serum sFas is associated with active renal SLE, and active disease and flare over time, while sFasL/sFas ratio is negatively associated with disease activity and organ damage accrual. Treatments correcting abnormal levels of sFas/FasL may be worthy of evaluation in SLE.
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http://dx.doi.org/10.1136/lupus-2019-000375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7299016PMC
June 2020

Not from Venus, not from Mars - all equally superstars.

Authors:
Fabienne Mackay

Nat Immunol 2020 03;21(3):238

Department of Microbiology and Immunology, School of Biomedical Sciences and The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.

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http://dx.doi.org/10.1038/s41590-020-0605-9DOI Listing
March 2020

Machine learning applied to whole-blood RNA-sequencing data uncovers distinct subsets of patients with systemic lupus erythematosus.

Clin Transl Immunology 2019 12;8(12):e01093. Epub 2019 Dec 12.

Department of Microbiology and Immunology University of Melbourne at the Peter Doherty Institute for Infection and Immunity Melbourne VIC Australia.

Objectives: Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease that is difficult to treat. There is currently no optimal stratification of patients with SLE, and thus, responses to available treatments are unpredictable. Here, we developed a new stratification scheme for patients with SLE, based on the computational analysis of patients' whole-blood transcriptomes.

Methods: We applied machine learning approaches to RNA-sequencing (RNA-seq) data sets to stratify patients with SLE into four distinct clusters based on their gene expression profiles. A meta-analysis on three recently published whole-blood RNA-seq data sets was carried out, and an additional similar data set of 30 patients with SLE and 29 healthy donors was incorporated in this study; a total of 161 patients with SLE and 57 healthy donors were analysed.

Results: Examination of SLE clusters, as opposed to unstratified SLE patients, revealed underappreciated differences in the pattern of expression of disease-related genes relative to clinical presentation. Moreover, gene signatures correlated with flare activity were successfully identified.

Conclusion: Given that SLE disease heterogeneity is a key challenge hindering the design of optimal clinical trials and the adequate management of patients, our approach opens a new possible avenue addressing this limitation via a greater understanding of SLE heterogeneity in humans. Stratification of patients based on gene expression signatures may be a valuable strategy allowing the identification of separate molecular mechanisms underpinning disease in SLE. Further, this approach may have a use in understanding the variability in responsiveness to therapeutics, thereby improving the design of clinical trials and advancing personalised therapy.
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http://dx.doi.org/10.1002/cti2.1093DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6946916PMC
December 2019

Distinguishing naive- from memory-derived human B cells during acute responses.

Clin Transl Immunology 2019 13;8(11):e01090. Epub 2019 Nov 13.

WHO Collaborating Centre for Reference and Research on Influenza VIDRL at the Peter Doherty Institute for Infection and Immunity Melbourne VIC Australia.

Objectives: A fundamental question in influenza research is whether antibody titre decline upon successive exposure to variant strains is consequent to recall of cross-reactive memory B cells that competitively inhibit naive B-cell responses. In connection, it is not clear whether naive and memory B cells remain phenotypically distinct acutely after activation such that they may be distinguished .

Methods: Here, we first compared the capacity of anti-Ig and Toll-like-receptor (TLR) 7/8 and TLR9 agonists (R848 and CpG) to augment human B-cell differentiation induced by IL-21 and sCD40L. The conditions that induced optimal differentiation were then used to compare the post-activation phenotype of sort-purified naive and memory B-cell subsets by FACS and antibody-secreting cell (ASC) ELISPOT.

Results: Sort-purified naive and memory B cells underwent robust plasmablast and ASC formation when stimulated with R848, but not CpG, and co-cultured with monocytes. This coincided with increased IL-1β and IL-6 production when B cells were co-cultured with monocytes and stimulated with R848, but not CpG. Naive B cells underwent equivalent ASC generation, but exhibited less class-switch and modulation of CD27, CD38 and CD20 expression than memory B cells after stimulation with R848 and monocytes for 6 days.

Conclusion: Stimulation with R848, IL-21 and sCD40L in the presence of monocytes induces robust differentiation and ASC generation from both naive and memory B-cells. However, naive and memory B cells retain key phenotypic differences after activation that may facilitate discrimination and better characterisation of acute responses to variant antigens.
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http://dx.doi.org/10.1002/cti2.1090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6851823PMC
November 2019

Microbiota-Derived Short-Chain Fatty Acids Promote the Memory Potential of Antigen-Activated CD8 T Cells.

Immunity 2019 08 1;51(2):285-297.e5. Epub 2019 Jul 1.

Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, VIC 3010, Australia. Electronic address:

Interactions with the microbiota influence many aspects of immunity, including immune cell development, differentiation, and function. Here, we examined the impact of the microbiota on CD8 T cell memory. Antigen-activated CD8 T cells transferred into germ-free mice failed to transition into long-lived memory cells and had transcriptional impairments in core genes associated with oxidative metabolism. The microbiota-derived short-chain fatty acid (SCFA) butyrate promoted cellular metabolism, enhanced memory potential of activated CD8 T cells, and SCFAs were required for optimal recall responses upon antigen re-encounter. Mechanistic experiments revealed that butyrate uncoupled the tricarboxylic acid cycle from glycolytic input in CD8 T cells, which allowed preferential fueling of oxidative phosphorylation through sustained glutamine utilization and fatty acid catabolism. Our findings reveal a role for the microbiota in promoting CD8 T cell long-term survival as memory cells and suggest that microbial metabolites guide the metabolic rewiring of activated CD8 T cells to enable this transition.
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http://dx.doi.org/10.1016/j.immuni.2019.06.002DOI Listing
August 2019

Analysis of serum B cell-activating factor from the tumor necrosis factor family (BAFF) and its soluble receptors in systemic lupus erythematosus.

Clin Transl Immunology 2019 21;8(4):e01047. Epub 2019 Apr 21.

Rheumatology Research Group Centre for Inflammatory Diseases School of Clinical Sciences at Monash Health Monash University Clayton VIC Australia.

Objectives: To determine the presence and clinical associations of the soluble receptors of B cell-activating factor from the tumor necrosis factor family (BAFF) in serum of patients with systemic lupus erythematosus (SLE).

Methods: Serum BAFF and soluble BAFF receptor (sBAFF-R) were quantified using ELISA, and soluble B cell maturation antigen (sBCMA) and transmembrane activator and cyclophilin ligand interactor (sTACI) by Luminex, in 87 SLE patients and 17 healthy controls (HC). Disease activity and organ damage were assessed using SLE Disease Activity Index 2000 (SLEDAI-2K) and Systemic Lupus International Collaborating Clinics (SLICC) SLE Damage Index (SDI), respectively.

Results: BAFF and all receptors were detectable in all serum samples. Serum sBCMA and sTACI, but not sBAFF-R, were significantly higher in SLE than in HC. Serum BAFF was also increased in SLE, but this association was attenuated after adjusting for age and ethnicity. Increased serum BAFF was associated with flare and organ damage. Increased serum sBCMA was associated with the presence of anti-dsDNA, but not with overall or organ-specific disease activity, flare or organ damage. Neither sTACI nor sBAFF-R was associated with any SLE clinical parameters in multivariable analysis. While serum BAFF correlated negatively with sBAFF-R in HC, no statistically significant correlations were observed between BAFF and its receptors in SLE patients.

Conclusion: Serum BAFF was associated with flare and organ damage independent of the presence of its soluble receptors. While sBCMA was associated with anti-dsDNA positivity, other soluble BAFF receptors were not associated with SLE clinical indicators.
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http://dx.doi.org/10.1002/cti2.1047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6475618PMC
April 2019

Serum soluble Fas and Fas ligand (FasL) in primary Sjögren's syndrome.

Clin Exp Rheumatol 2019 May-Jun;37 Suppl 118(3):254-256. Epub 2019 Feb 15.

Rheumatology Department, The Queen Elizabeth Hospital, Woodville, and Discipline of Medicine, University of Adelaide, Australia.

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October 2019

Recirculating Intestinal IgA-Producing Cells Regulate Neuroinflammation via IL-10.

Cell 2019 01 3;176(3):610-624.e18. Epub 2019 Jan 3.

Department of Immunology, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address:

Plasma cells (PC) are found in the CNS of multiple sclerosis (MS) patients, yet their source and role in MS remains unclear. We find that some PC in the CNS of mice with experimental autoimmune encephalomyelitis (EAE) originate in the gut and produce immunoglobulin A (IgA). Moreover, we show that IgA PC are dramatically reduced in the gut during EAE, and likewise, a reduction in IgA-bound fecal bacteria is seen in MS patients during disease relapse. Removal of plasmablast (PB) plus PC resulted in exacerbated EAE that was normalized by the introduction of gut-derived IgA PC. Furthermore, mice with an over-abundance of IgA PB and/or PC were specifically resistant to the effector stage of EAE, and expression of interleukin (IL)-10 by PB plus PC was necessary and sufficient to confer resistance. Our data show that IgA PB and/or PC mobilized from the gut play an unexpected role in suppressing neuroinflammation.
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http://dx.doi.org/10.1016/j.cell.2018.11.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6903689PMC
January 2019

Analysis of urinary macrophage migration inhibitory factor in systemic lupus erythematosus.

Lupus Sci Med 2018 19;5(1):e000277. Epub 2018 Oct 19.

Centre for Inflammatory Diseases, School of Clinical Sciences at Monash Health, Monash University, Clayton, Victoria, Australia.

Objective: To characterise the clinical relevance of urinary macrophage migration inhibitory factor (uMIF) concentrations in patients with systemic lupus erythematosus (SLE).

Methods: MIF, adjusted for urine creatinine, was quantified by ELISA in urine samples from 64 prospectively recruited patients with SLE. Serum MIF and urinary monocyte chemoattractant protein 1 (uMCP-1) were quantified by ELISA in a subset of patients (n = 39). Disease activity was assessed using the SLE Disease Activity Index-2000 (SLEDAI-2K) score.

Results: uMIF was detectable in all patients with SLE. uMIF was positively correlated with overall SLEDAI-2K, was significantly higher in patients with SLE with high disease activity (SLEDAI-2K≥10) compared with those with inactive disease (SLEDAI-2K<4), and this association remained significant after adjusting for ethnicity, flare and use of immunosuppressants. uMIF was also significantly higher in SLE patients with flare of disease, although not confirmed in multivariable analysis. No significant differences in uMIF levels were observed according to the presence of renal disease activity, as assessed by renal SLEDAI-2K or biopsy-confirmed lupus nephritis. In contrast, uMCP-1 was significantly higher in SLE patients with active renal disease. uMIF expression was not associated with irreversible organ damage accrual or glucocorticoid use.

Conclusions: These data suggest uMIF as a potential overall but not renal-specific SLE biomarker, whereas uMCP-1 is a renal-specific SLE biomarker.
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http://dx.doi.org/10.1136/lupus-2018-000277DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6203042PMC
October 2018

Methotrexate and BAFF interaction prevents immunization against TNF inhibitors.

Ann Rheum Dis 2018 10 23;77(10):1463-1470. Epub 2018 Jun 23.

Rheumatology Department, Université Paris-Sud-CEA-INSERM U1184, Immunology of Viral Infections and Autoimmune Diseases, Hôpitaux Universitaires Paris-Sud-Assistance Publique-Hôpitaux de Paris (AP-HP), Le Kremlin Bicêtre, France.

Objectives: TNF inhibitors (TNFi) can induce anti-drug antibodies (ADA) in patients with autoimmune diseases (AID) leading to clinical resistance. We explored a new way of using methotrexate (MTX) to decrease this risk of immunisation.

Methods: We treated BAFF transgenic (BAFFtg) mice, a model of AID in which immunisation against biologic drugs is high, with different TNFi. We investigated the effect of a single course of MTX during the first exposure to TNFi. Wild-type (WT) and BAFFtg mice were compared for B-Cell surface markers involved in MTX-related purinergic metabolism, adenosine production and regulatory B-cells (Bregs).We translated the study to macaques and patients with rheumatoid arthritis from the ABIRISK cohort to determine if there was an interaction between serum BAFF levels and MTX that prevented immuniation.

Results: In BAFFtg but not in WT mice or macaques, a single course of MTX prevented immunisation against TNFi and maintained drug concentration for over 52 weeks. BAFFtg mice B-cells expressed more CD73 and CD39 compared to WT mice. MTX induced adenosine release from B cells and increased Bregs and precursors. Use of CD73 blocking antibodies reversed MTX-induced tolerance. In patients from the ABIRISK cohort treated with TNFi for chronic inflammatory diseases, high BAFF serum level correlated with absence of ADA to TNFi only in patients cotreated with MTX but not in patients on TNFi monotherapy.

Conclusion: MTX and BAFF interact in mice where CD73, adenosine and regulatory B cells were identified as key actors in this phenomenon. MTX and BAFF also interact in patients to prevent ADA formation.
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http://dx.doi.org/10.1136/annrheumdis-2018-213403DOI Listing
October 2018

A loop region of BAFF controls B cell survival and regulates recognition by different inhibitors.

Nat Commun 2018 03 23;9(1):1199. Epub 2018 Mar 23.

Department of Biochemistry, University of Lausanne, 1066, Epalinges, Switzerland.

The B cell survival factor (TNFSF13B/BAFF) is often elevated in autoimmune diseases and is targeted in the clinic for the treatment of systemic lupus erythematosus. BAFF contains a loop region designated the flap, which is dispensable for receptor binding. Here we show that the flap of BAFF has two functions. In addition to facilitating the formation of a highly active BAFF 60-mer as shown previously, it also converts binding of BAFF to TNFRSF13C (BAFFR) into a signaling event via oligomerization of individual BAFF-BAFFR complexes. Binding and activation of BAFFR can therefore be targeted independently to inhibit or activate the function of BAFF. Moreover, structural analyses suggest that the flap of BAFF 60-mer temporarily prevents binding of an anti-BAFF antibody (belimumab) but not of a decoy receptor (atacicept). The observed differences in profiles of BAFF inhibition may confer distinct biological and clinical efficacies to these therapeutically relevant inhibitors.
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http://dx.doi.org/10.1038/s41467-018-03323-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5865128PMC
March 2018

Molecular control of B-cell homeostasis in health and malignancy.

Immunol Cell Biol 2018 05 24;96(5):453-462. Epub 2018 Mar 24.

The Department of Microbiology and Immunology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia.

Altered B-cell homeostasis underlies a wide range of pathologies, from cancers to autoimmunity and immunodeficiency. The molecular safeguards against those disorders, which also allow effective immune responses, are therefore particularly critical. Here, we review recent findings detailing the fine control of B-cell homeostasis, during B-cell development, maturation in the periphery and during activation and differentiation into antibody-producing cells.
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http://dx.doi.org/10.1111/imcb.12030DOI Listing
May 2018

Arginine methylation catalyzed by PRMT1 is required for B cell activation and differentiation.

Nat Commun 2017 10 12;8(1):891. Epub 2017 Oct 12.

Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia.

Arginine methylation catalyzed by protein arginine methyltransferases (PRMT) is a common post-translational modification in mammalian cells, regulating many important functions including cell signalling, proliferation and differentiation. Here we show the role of PRMT1 in B-cell activation and differentiation. PRMT1 expression and activity in human and mouse peripheral B cells increases in response to in vitro or in vivo activation. Deletion of the Prmt1 gene in mature B cells establishes that although the frequency and phenotype of peripheral B cell subsets seem unaffected, immune responses to T-cell-dependent and -independent antigens are substantially reduced. In vitro activation of Prmt1-deficient B cells with a variety of mitogens results in diminished proliferation, differentiation and survival, effects that are correlated with altered signal transduction from the B cell receptor. Thus PRMT1 activity in B cells is required for correct execution of multiple processes that in turn are necessary for humoral immunity.PRMT1 is an arginine methyltransferase involved in a variety of cell functions. Here the authors delete PRMT1 specifically in mature B cells to show the importance of arginine methylation for B cell proliferation, differentiation and survival, and thereby for humoral immunity.
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http://dx.doi.org/10.1038/s41467-017-01009-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5638811PMC
October 2017

Foxp3 Tregs are recruited to the retina to repair pathological angiogenesis.

Nat Commun 2017 09 29;8(1):748. Epub 2017 Sep 29.

Department of Diabetes, The Central Clinical School, Monash University, Melbourne, VIC, 3004, Australia.

Neovascular retinopathies are major causes of vision loss; yet treatments to prevent the condition are inadequate. The role of regulatory T cells in neovascular retinopathy is unknown. Here we show that in retinopathy regulatory T cells are transiently increased in lymphoid organs and the retina, but decline when neovascularization is established. The decline is prevented following regulatory T cells expansion with an IL-2/anti-IL-2 mAb complex or the adoptive transfer of regulatory T cells. Further, both approaches reduce vasculopathy (vaso-obliteration, neovascularization, vascular leakage) and alter the activation of Tmem119 retinal microglia. Our in vitro studies complement these findings, showing that retinal microglia co-cultured with regulatory T cells exhibit a reduction in co-stimulatory molecules and pro-inflammatory mediators that is attenuated by CTLA-4 blockade. Collectively, we demonstrate that regulatory T cells are recruited to the retina and, when expanded in number, repair the vasculature. Manipulation of regulatory T cell numbers is a previously unrecognized, and promising avenue for therapies to prevent blinding neovascular retinopathies.The local immune responses in the eye are attenuated to preserve sight. Surprisingly, Deliyanti et al. show that regulatory T cells (Tregs) take an active role in protecting the eye from neovascularization in oxygen-induced retinopathy, and that interventions that augment the retinal Treg numbers reduce neovascular retinopathy in mice.
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http://dx.doi.org/10.1038/s41467-017-00751-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5622066PMC
September 2017

Protective Effect of Inflammasome Activation by Hydrogen Peroxide in a Mouse Model of Septic Shock.

Crit Care Med 2017 Feb;45(2):e184-e194

1Diabetes Complications, BakerIDI Heart and Diabetes Institute, Melbourne, VIC, Australia. 2Department of Anaesthesia and Intensive Care, CHRU La Cavale Blanche, Université de Bretagne Ouest, Brest, France. 3Australian and New Zealand Intensive Care Research Centre, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia. 4Inflammation Division, The Walter and Eliza Hall Institute, Parkville, VIC, Australia. 5Departments of Chemistry and Molecular and Cell Biology and the Howard Hughes Medical Institute, University of California, Berkeley, CA.

Objectives: To study the effect of a lack of antioxidant defenses during lethal pneumonia induced by Klebsiella pneumonia, compared to wild-type mice.

Setting: Laboratory experiments.

Subjects: C57Bl6 and glutathione peroxidase 1 knockout mice.

Intervention: Murine acute pneumonia model induced by Klebsiella pneumonia.

Measurements And Main Results: We show here that despite a lack of one of the major antioxidant defense enzymes, glutathione peroxidase 1 knockout mice are protected during lethal pneumonia induced by Klebsiella pneumonia, compared to wild-type mice. Furthermore, this protective effect was suppressed when antioxidant defenses were restored. Infected glutathione peroxidase 1 mice showed an early and significant, albeit transient, increase in the activity of the NOD-like receptor family, pyrin domain containing 3 inflammasome when compared with wild-type mice. The key role of the NOD-like receptor family, pyrin domain containing 3 inflammasome during acute pneumonia was confirmed in vivo when the protective effect was suppressed by treating glutathione peroxidase 1 mice with an interleukin-1 receptor antagonist. Additionally we report, in vitro, that increased concentrations of active caspase-1 and interleukin-1β are related to an increased concentration of hydrogen peroxide in bacterially infected glutathione peroxidase 1 macrophages and that restoring hydrogen peroxide antioxidant defenses suppressed this effect.

Conclusions: Our findings demonstrate that, contrary to current thinking, an early intervention targeting NOD-like receptor family, pyrin domain containing 3 inflammasome activity induces a timely and efficient activation of the innate immune response during acute infection. Our findings also demonstrate a role for hydrogen peroxide in the mechanisms tightly regulating NOD-like receptor family, pyrin domain containing 3 activation.
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http://dx.doi.org/10.1097/CCM.0000000000002070DOI Listing
February 2017

Antibodies That Block or Activate Mouse B Cell Activating Factor of the Tumor Necrosis Factor (TNF) Family (BAFF), Respectively, Induce B Cell Depletion or B Cell Hyperplasia.

J Biol Chem 2016 09 22;291(38):19826-34. Epub 2016 Jul 22.

From the Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland,

B cell activating factor of the TNF family (BAFF), also known as B lymphocyte stimulator, is a ligand required for the generation and maintenance of B lymphocytes. In this study, the ability of different monoclonal antibodies to recognize, inhibit, or activate mouse BAFF was investigated. One of them, a mouse IgG1 named Sandy-2, prevented the binding of BAFF to all of its receptors, BAFF receptor, transmembrane activator and calcium modulating ligand interactor, and B cell maturation antigen, at a stoichiometric ratio; blocked the activity of mouse BAFF on a variety of cell-based reporter assays; and antagonized the prosurvival action of BAFF on primary mouse B cells in vitro A single administration of Sandy-2 in mice induced B cell depletion within 2 weeks, down to levels close to those observed in BAFF-deficient mice. This depletion could then be maintained with a chronic treatment. Sandy-2 and a previously described rat IgG1 antibody, 5A8, also formed a pair suitable for the sensitive detection of endogenous circulating BAFF by ELISA or using a homogenous assay. Interestingly, 5A8 and Sandy-5 displayed activities opposite to that of Sandy-2 by stimulating recombinant BAFF in vitro and endogenous BAFF in vivo These tools will prove useful for the detection and functional manipulation of endogenous mouse BAFF and provide an alternative to the widely used BAFF receptor-Fc decoy receptor for the specific depletion of BAFF in mice.
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http://dx.doi.org/10.1074/jbc.M116.725929DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025672PMC
September 2016

NFκB1 is essential to prevent the development of multiorgan autoimmunity by limiting IL-6 production in follicular B cells.

J Exp Med 2016 Apr 28;213(4):621-41. Epub 2016 Mar 28.

Burnet Institute, Melbourne, VIC 3004, Australia Immunology, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia

We examined the role of NFκB1 in the homeostasis and function of peripheral follicular (Fo) B cells. Aging mice lacking NFκB1 (Nfκb1(-/-)) develop lymphoproliferative and multiorgan autoimmune disease attributed in large part to the deregulated activity of Nfκb1(-/-)Fo B cells that produce excessive levels of the proinflammatory cytokine interleukin 6 (IL-6). Despite enhanced germinal center (GC) B cell differentiation, the formation of GC structures was severely disrupted in the Nfκb1(-/-)mice. Bone marrow chimeric mice revealed that the Fo B cell-intrinsic loss of NFκB1 led to the spontaneous generation of GC B cells. This was primarily the result of an increase in IL-6 levels, which promotes the differentiation of Fo helper CD4(+)T cells and acts in an autocrine manner to reduce antigen receptor and toll-like receptor activation thresholds in a population of proliferating IgM(+)Nfκb1(-/-)Fo B cells. We demonstrate that p50-NFκB1 represses Il-6 transcription in Fo B cells, with the loss of NFκB1 also resulting in the uncontrolled RELA-driven transcription of Il-6.Collectively, our findings identify a previously unrecognized role for NFκB1 in preventing multiorgan autoimmunity through its negative regulation of Il-6 gene expression in Fo B cells.
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http://dx.doi.org/10.1084/jem.20151182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4821646PMC
April 2016

The bigger B cell picture.

Authors:
Fabienne Mackay

Nat Rev Immunol 2016 Mar 25;16(3):133. Epub 2016 Jan 25.

School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Victoria 3010, Australia.

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http://dx.doi.org/10.1038/nri.2016.3DOI Listing
March 2016

Editorial overview: Autoimmunity.

Curr Opin Immunol 2015 Dec 25;37:v-vii. Epub 2015 Oct 25.

Inaugural School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Australia. Electronic address:

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http://dx.doi.org/10.1016/j.coi.2015.10.004DOI Listing
December 2015

BAFF-driven autoimmunity requires CD19 expression.

J Autoimmun 2015 Aug 20;62:1-10. Epub 2015 Jun 20.

Faculty of Medicine, Nursing and Health Sciences, Department of Immunology, Central Clinical School, Monash University, Commercial Rd, Melbourne 3004, Australia. Electronic address:

B cell activating factor of the tumor necrosis factor family (BAFF or BLyS) is a critical factor for B cell survival and maturation. BAFF-transgenic (BAFF-Tg) mice develop autoimmunity that resembles systemic lupus erythematosus (SLE) in a T cell-independent but MyD88-dependent manner, implicating toll-like receptor (TLR) signaling. The specific B cell subtypes that make pro-inflammatory autoantibodies in BAFF-Tg mice are TLR-activated innate B cells known as marginal zone (MZ) and B1 B cells. These cells infiltrate the salivary glands and kidneys of diseased BAFF-Tg mice. However, loss of B1a or MZ B cells does not protect BAFF-Tg mice against disease, suggesting that B1b B cells might be the important pathogenic B cell subset. To test this hypothesis, we have generated BAFF-Tg mice that retained follicular B cells, but are deficient in B1a, B1b and MZ B cells, by crossing BAFF-Tg mice to CD19-deficient mice (BTg-CD19(-/-)). The BTg-CD19(-/-) mice did not produce autoantibodies and were protected from splenomegaly, kidney pathology and all signs of autoimmunity. This work suggests that B1b B cells, rather than MZ or B1a B cells, are sufficient and possibly required for the development of autoimmunity. Loss of the majority of innate-like B cells was able to protect BAFF-Tg mice from developing disease, so we can now conclude that autoimmunity induced by excessive BAFF production requires B1b B cells and CD19 signaling.
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http://dx.doi.org/10.1016/j.jaut.2015.06.001DOI Listing
August 2015

Chemokine Signaling Controls Integrity of Radial Glial Scaffold in Developing Spinal Cord and Consequential Proper Position of Boundary Cap Cells.

J Neurosci 2015 Jun;35(24):9211-24

Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.

Radial glial cells are the neural progenitors of the developing CNS and have long radial processes that guide radially migrating neurons. The integrity of the radial glial scaffold, in particular proper adhesion between the endfeet of radial processes and the pial basement membrane (BM), is important for the cellular organization of the CNS, as indicated by evidence emerging from the developing cortex. However, the mechanisms underlying the maintenance of radial glial scaffold integrity during development, when the neuroepithelium rapidly expands, are still poorly understood. Here, we addressed this issue in the developing mouse spinal cord. We show that CXCR4, a receptor of chemokine CXCL12, is expressed in spinal cord radial glia. Conditional knock-out of Cxcr4 in radial glia caused disrupted radial glial scaffold with gaps at the pial endfeet layer and consequentially led to an invasion of boundary cap (BC) cells into the spinal cord. Because BC cells are PNS cells normally positioned at the incoming and outgoing axonal roots, their invasion into the spinal cord suggests a compromised CNS/PNS boundary in the absence of CXCL12/CXCR4 signaling. Both disrupted radial glial scaffold and invasion of BC cells into the CNS were also present in mice deficient in CXCR7, a second receptor of CXCL12. We further show that CXCL12 signaling promotes the radial glia adhesion to BM components and activates integrin β1 avidity. Our study unravels a novel molecular mechanism that deploys CXCL12/CXCR4/CXCR7 for the maintenance of radial glial scaffold integrity, which in turn safeguards the CNS/PNS boundary during spinal cord development.
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http://dx.doi.org/10.1523/JNEUROSCI.0156-15.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6605157PMC
June 2015

Deleting the BAFF receptor TACI protects against systemic lupus erythematosus without extensive reduction of B cell numbers.

J Autoimmun 2015 Jul 29;61:9-16. Epub 2015 May 29.

Department of Immunology, Central Clinical School, Monash University, Melbourne 3004, Australia.

B cell-activating factor of the TNF family (BAFF) is an essential B cell survival factor. However, high levels of BAFF promote systemic lupus erythematosus (SLE) in mice and humans. Belimumab (anti-human BAFF) limits B cell survival and is approved for use in patients with SLE. Surprisingly, the efficacy of rituximab (anti-human CD20) in SLE remains controversial, despite depleting B cells more potently than belimumab. This raises the question of whether B cell depletion is really the mechanism of action of belimumab. In BAFF transgenic mice, SLE development is T cell-independent but relies on innate activation of B cells via TLRs, and TLR expression is modulated by the BAFF receptor TACI. Here, we show that loss of TACI on B cells protected against BAFF-mediated autoimmune manifestations while preserving B cells, suggesting that loss of BAFF signaling through TACI rather than loss of B cells may underpin the effect of belimumab in the clinic. Therefore, B cell-sparing blockade of TACI may offer a more specific and safer therapeutic alternative to broad B cell depletion in SLE.
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http://dx.doi.org/10.1016/j.jaut.2015.04.007DOI Listing
July 2015

The activin A antagonist follistatin inhibits cystic fibrosis-like lung inflammation and pathology.

Immunol Cell Biol 2015 Jul 10;93(6):567-74. Epub 2015 Mar 10.

1] Department of Allergy, Immunology & Respiratory Medicine, Central Clinical School, Monash University, Melbourne, Victoria, Australia [2] Department of Immunology, Central Clinical School, Monash University, Melbourne, Victoria, Australia [3] Department of Allergy, Immunology & Respiratory Medicine, The Alfred Hospital, Melbourne, Victoria, Australia.

Cystic fibrosis (CF) is the most common life-limiting genetically acquired respiratory disorder. Patients with CF have thick mucus obstructing the airways leading to recurrent infections, bronchiectasis and neutrophilic airway inflammation culminating in deteriorating lung function. Current management targets airway infection and mucus clearance, but despite recent advances in care, life expectancy is still only 40 years. We investigated whether activin A is elevated in CF lung disease and whether inhibiting activin A with its natural antagonist follistatin retards lung disease progression. We measured serum activin A levels, lung function and nutritional status in CF patients. We studied the effect of activin A on CF lung pathogenesis by treating newborn CF transgenic mice (β-ENaC) intranasally with the natural activin A antagonist follistatin. Activin A levels were elevated in the serum of adult CF patients, and correlated inversely with lung function and body mass index. Follistatin treatment of newborn β-ENaC mice, noted for respiratory pathology mimicking human CF, decreased the airway activin A levels and key features of CF lung disease including mucus hypersecretion, airway neutrophilia and levels of mediators that regulate inflammation and chemotaxis. Follistatin treatment also increased body weight and survival of β-ENaC mice, with no evidence of local or systemic toxicity. Our findings demonstrate that activin A levels are elevated in CF and provide proof-of-concept for the use of the activin A antagonist, follistatin, as a therapeutic in the long-term management of lung disease in CF patients.
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http://dx.doi.org/10.1038/icb.2015.7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4495664PMC
July 2015

Efficient conditional gene expression following transplantation of retrovirally transduced bone marrow stem cells.

J Immunol Methods 2015 Jan 8;416:183-8. Epub 2014 Nov 8.

Department of Immunology, Central Clinical School, Monash University, Australia. Electronic address:

Retroviral gene therapy combined with bone marrow stem cell transplantation can be used to generate mice with ectopic gene expression in the bone marrow compartment in a quick and cost effective manner when compared to generating and maintaining transgenic mouse lines. However a limitation of this procedure is the lack of cell specificity in gene expression that is associated with the use of endogenous retroviral promoters. Restricting gene expression to specific cell subsets utilising tissue-specific promoter driven retroviral vectors is a challenge. Here we describe the generation of conditional expression of retrovirally encoded genes in specific bone marrow derived cell lineages utilising a Cre-dependent retroviral vector. By utilising Lck and CD19 restricted Cre transgenic bone marrow stem cells, we generate chimeric animals with T or B lymphocyte restricted gene expression respectively. The design of the Cre-dependent retroviral vector enables expression of encoded MOG and GFP genes only in association with Cre mediated DNA inversion. Importantly this strategy does not significantly increase the size of the retroviral vector; as such we are able to generate bone marrow chimeric animals with significantly higher chimerism levels than previous studies utilising Cre-dependent retroviral vectors and Cre transgenic bone marrow stem cells. This demonstrates that the use of Cre-dependent retroviral vectors is able to yield high chimerism levels for experimental use and represent a viable alternative to generating transgenic animals.
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http://dx.doi.org/10.1016/j.jim.2014.11.002DOI Listing
January 2015

IL-10 regulates Aicda expression through miR-155.

J Leukoc Biol 2015 Jan 7;97(1):71-8. Epub 2014 Nov 7.

*Faculty of Medicine, Department of Immunology, Monash University, Prahran, and Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia; The Department of Experimental Medicine, University of Melbourne, Parkville, Victoria, Australia; Division of Molecular Medicine, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia; Centre for Cancer Research, Monash Institute of Medical Research-Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia; and School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Ireland

Aicda is a critical component of antibody class-switching in B cells. In this work, we study the impact of TLR4 activation and IL-10 stimulation on Aicda expression in B cells. Through the global analysis of miRNAs in response to TLR4 activation, in combination with IL-10 stimulation, we identified that IL-10 can suppress TLR4-induced miR-155 expression, an effect that resulted in enhanced Aicda expression. Furthermore, when preventing miR-155 control of Aicda expression, by genetic mutation of its target site in the Aicda mRNA, IL-10 could further potentiate Aicda expression. Given that miR-155 expression is lost, and expression levels of both Aicda and IL-10 are high in diseases, such as Burkitt's lymphoma, our results suggest a stringent and sophisticated control of Aicda by a novel IL-10/miR-155 axis, where the imbalance of IL-10 and/or miR-155 may contribute to disease pathogenesis.
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http://dx.doi.org/10.1189/jlb.2A0314-178RDOI Listing
January 2015

The tyrosine kinase Lyn limits the cytokine responsiveness of plasma cells to restrict their accumulation in mice.

Sci Signal 2014 Aug 12;7(338):ra77. Epub 2014 Aug 12.

The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia. Department of Experimental Medicine, University of Melbourne, Parkville, Victoria 3052, Australia.

Maintenance of an appropriate number of plasma cells, long-lived antibody-producing cells that are derived from B cells, is essential for maintaining immunological memory while limiting disease. Plasma cell survival relies on extrinsic factors, the limited availability of which determines the size of the plasma cell population. Mice deficient in the nonreceptor tyrosine kinase Lyn are prone to an autoimmune disease that is characterized by inflammation and an excess of plasma cells (plasmacytosis). We demonstrated that the plasmacytosis was intrinsic to B cells and independent of inflammation. We also showed that Lyn attenuated signaling by signal transducer and activator of transcription 3 (STAT3) and STAT5 in response to the cytokines interleukin-6 (IL-6) and IL-3, respectively, in two previously uncharacterized plasma cell signaling pathways. Thus, in the absence of Lyn, the survival of plasma cells was improved, which enabled the plasma cells to become established in excess numbers in niches in vivo. These data identify Lyn as a key regulator of survival signaling in plasma cells, limiting plasma cell accumulation and autoimmune disease susceptibility.
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http://dx.doi.org/10.1126/scisignal.2005105DOI Listing
August 2014

Roles of ligands from the TNF superfamily in B cell development, function, and regulation.

Semin Immunol 2014 Jun 2;26(3):191-202. Epub 2014 Jul 2.

Department of Immunology, Monash University, Central Clinical School, Alfred Medical Research and Education Precinct (AMREP), Commercial Road, Melbourne, Victoria 3004, Australia. Electronic address:

Most ligands from the tumour necrosis factor (TNF) superfamily play very important roles in the immune system, and particularly so in B lymphocyte biology. TNF ligands are essential to many aspects of normal B cell biology from development in the bone marrow to maturation in the periphery as well as for activation and differentiation into germinal centre, memory or plasma cells. TNF ligands also influence other aspects of B cell biology such as their ability to present antigens or regulate immune responses. Importantly, inadequate regulation of many TNF ligands is associated with B cell disorders including autoimmunity and cancers. As a result, inhibitors of a number of TNF ligands have been tested in the clinic, with some becoming very successful approved treatments alleviating B cell-mediated pathologies.
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http://dx.doi.org/10.1016/j.smim.2014.06.001DOI Listing
June 2014