MOG autoantibodies trigger a tightly-controlled FcR and BTK-driven microglia proliferative response.

Autoantibodies are a hallmark of numerous neurological disorders, including multiple sclerosis, autoimmune encephalitides and neuromyelitis optica. Whilst well understood in peripheral myeloid cells, the pathophysiological significance of autoantibody-induced Fc receptor signalling in microglia remains unknown, in part due to the lack of a robust in vivo model. Moreover, the application of therapeutic antibodies for neurodegenerative disease also highlights the importance of understanding Fc receptor signalling in microglia.

Next-generation Bruton's tyrosine kinase inhibitor BIIB091 selectively and potently inhibits B cell and Fc receptor signaling and downstream functions in B cells and myeloid cells.

Objectives: Bruton's tyrosine kinase (BTK) plays a non-redundant signaling role downstream of the B-cell receptor (BCR) in B cells and the receptors for the Fc region of immunoglobulins (FcR) in myeloid cells. Here, we characterise BIIB091, a novel, potent, selective and reversible small-molecule inhibitor of BTK.

Methods: BIIB091 was evaluated and in preclinical models and in phase 1 clinical trial.

Differential accumulation of storage bodies with aging defines discrete subsets of microglia in the healthy brain.

To date, microglia subsets in the healthy CNS have not been identified. Utilizing autofluorescence (AF) as a discriminating parameter, we identified two novel microglia subsets in both mice and non-human primates, termed autofluorescence-positive (AF) and negative (AF). While their proportion remained constant throughout most adult life, the AF signal linearly and specifically increased in AF microglia with age and correlated with a commensurate increase in size and complexity of lysosomal storage bodies, as detected by transmission electron microscopy and LAMP1 levels.

NOD2 modulates immune tolerance via the GM-CSF-dependent generation of CD103 dendritic cells.

Four decades ago, it was identified that muramyl dipeptide (MDP), a peptidoglycan-derived bacterial cell wall component, could display immunosuppressive functions in animals through mechanisms that remain unexplored. We sought to revisit these pioneering observations because mutations in , the gene encoding the host sensor of MDP, are associated with increased risk of developing the inflammatory bowel disease Crohn's disease, thus suggesting that the loss of the immunomodulatory functions of NOD2 could contribute to the development of inflammatory disease. Here, we demonstrate that intraperitoneal (i.

γδ T Cell-Secreted XCL1 Mediates Anti-CD3-Induced Oral Tolerance.

Oral tolerance is defined as the specific suppression of cellular and/or humoral immune responses to an Ag by prior administration of the Ag through the oral route. Although the investigation of oral tolerance has classically involved Ag feeding, we have found that oral administration of anti-CD3 mAb induced tolerance through regulatory T (Treg) cell generation. However, the mechanisms underlying this effect remain unknown.

Smad7 Controls Immunoregulatory PDL2/1-PD1 Signaling in Intestinal Inflammation and Autoimmunity.

Smad7, a negative regulator of TGF-β signaling, has been implicated in the pathogenesis and treatment of inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC). Here, we found that Smad7 mediates intestinal inflammation by limiting the PDL2/1-PD1 axis in dendritic cells (DCs) and CD4T cells. Smad7 deficiency in DCs promotes TGF-β responsiveness and the co-inhibitory molecules PDL2/1 on DCs, and it further imprints T cell-PD1 signaling to promote Treg differentiation.

Acute microglia ablation induces neurodegeneration in the somatosensory system.

Previous studies have reported that microglia depletion leads to impairment of synapse formation and these cells rapidly repopulate from CNS progenitors. However, the impact of microglia depletion and repopulation in the long-term state of the CNS environment has not been characterized. Here, we report that acute and synchronous microglia depletion and subsequent repopulation induces gray matter microgliosis, neuronal death in the somatosensory cortex and ataxia-like behavior.

γδ T cells control humoral immune response by inducing T follicular helper cell differentiation.

γδ T cells have many known functions, including the regulation of antibody responses. However, how γδ T cells control humoral immunity remains elusive. Here we show that complete Freund's adjuvant (CFA), but not alum, immunization induces a subpopulation of CXCR5-expressing γδ T cells in the draining lymph nodes.

Systematic evaluation of RNA quality, microarray data reliability and pathway analysis in fresh, fresh frozen and formalin-fixed paraffin-embedded tissue samples.

Formalin-fixed paraffin-embedded (FFPE) tissues are valuable resources commonly used in pathology. However, formalin fixation modifies nucleic acids challenging the isolation of high-quality RNA for genetic profiling. Here, we assessed feasibility and reliability of microarray studies analysing transcriptome data from fresh, fresh-frozen (FF) and FFPE tissues.

Targeting latency-associated peptide promotes antitumor immunity.

Regulatory T cells (T) promote cancer by suppressing antitumor immune responses. We found that anti-LAP antibody, which targets the latency-associated peptide (LAP)/transforming growth factor-β (TGF-β) complex on T and other cells, enhances antitumor immune responses and reduces tumor growth in models of melanoma, colorectal carcinoma, and glioblastoma. Anti-LAP decreases LAP T, tolerogenic dendritic cells, and TGF-β secretion and is associated with CD8 T cell activation.

Disruption of the ATP/adenosine balance in CD39 mice is associated with handling-induced seizures.

Seizures are due to excessive, synchronous neuronal firing in the brain and are characteristic of epilepsy, the fourth most prevalent neurological disease. We report handling-induced and spontaneous seizures in mice deficient for CD39, a cell-surface ATPase highly expressed on microglial cells. CD39 mice with handling-induced seizures had normal input-output curves and paired-pulse ratio measured from hippocampal slices and lacked microgliosis, astrogliosis or overt cell loss in the hippocampus and cortex.

Isolation and high-dimensional phenotyping of gastrointestinal immune cells.

The gastrointestinal immune system plays a pivotal role in the host relationship with food antigens, the homeostatic microbiome and enteric pathogens. Here, we describe how to collect and process liver and intestinal samples to efficiently isolate and analyse resident immune cells. Furthermore, we describe a step-by-step methodology showing how to high-dimensionally immunophenotype resident leucocytes using cytometry by time-of-flight, providing a well-characterized antibody platform that allows the identification of every leucocyte subset simultaneously.

Combination of Mass Cytometry and Imaging Analysis Reveals Origin, Location, and Functional Repopulation of Liver Myeloid Cells in Mice.

Background & Aims: Resident macrophages are derived from yolk sac precursors and seed the liver during embryogenesis. Native cells may be replaced by bone marrow precursors during extensive injuries, irradiation, and infections. We investigated the liver populations of myeloid immune cells and their location, as well as the dynamics of phagocyte repopulation after full depletion.

Gut microbial metabolism drives transformation of MSH2-deficient colon epithelial cells.

The etiology of colorectal cancer (CRC) has been linked to deficiencies in mismatch repair and adenomatous polyposis coli (APC) proteins, diet, inflammatory processes, and gut microbiota. However, the mechanism through which the microbiota synergizes with these etiologic factors to promote CRC is not clear. We report that altering the microbiota composition reduces CRC in APC(Min/+)MSH2(-/-) mice, and that a diet reduced in carbohydrates phenocopies this effect.

Constitutive induction of intestinal Tc17 cells in the absence of hematopoietic cell-specific MHC class II expression.

The enteric pathogen Citrobacter rodentium induces a mucosal IL-17 response in CD4(+) T helper (Th17) cells that is dependent on the Nod-like receptors Nod1 and Nod2. Here, we sought to determine whether this early Th17 response required antigen presentation by major histocompatibility complex class II (MHCII) for full induction. At early phases of C.

Nod1 and Nod2 signaling does not alter the composition of intestinal bacterial communities at homeostasis.

Patients with inflammatory bowel diseases (IBD) harbour intestinal bacterial communities with altered composition compared with healthy counterparts; however, it is unknown whether changes in the microbiota are associated with genetic susceptibility of individuals for developing disease or instead reflect other changes in the intestinal environment related to the disease itself. Since deficiencies in the innate immune receptors Nod1 and Nod2 are linked to IBD, we tested the hypothesis that Nod-signaling alters intestinal immune profiles and subsequently alters bacterial community structure. We used qPCR to analyze expression patterns of selected immune mediators in the ileum and cecum of Nod-deficient mice compared with their Nod-sufficient littermates and assessed the relative abundance of major bacterial groups sampled from the ileum, cecum and colon.

Identification of a synthetic muramyl peptide derivative with enhanced Nod2 stimulatory capacity.

Muramyl peptides (MPs) represent the building blocks of bacterial peptidoglycan, a critical component of bacterial cell walls. MPs are well characterized for their immunomodulatory properties, and numerous studies have delineated the role of MPs or synthetic MP analogs in host defense, adjuvanticity and inflammation. More recently, Nod1 and Nod2 have been identified as the host sensors for specific MPs, and, in particular, Nod2 was shown to detect muramyl dipeptide (MDP), a MP found in both Gram-positive and Gram-negative bacterial cell walls.

Phenotyping of Nod1/2 double deficient mice and characterization of Nod1/2 in systemic inflammation and associated renal disease.

It is indispensable to thoroughly characterize each animal model in order to distinguish between primary and secondary effects of genetic changes. The present study analyzed Nod1 and Nod2 double deficient (Nod1/2 DKO) mice under physiological and inflammatory conditions. Nod1 and Nod2 are members of the Nucleotide-binding domain and Leucine-rich repeat containing Receptor (NLR) family.

Nod-like receptors in the control of intestinal inflammation.

The Nod-like receptor (NLR) family of intracellular pattern recognition molecules plays critical roles in the control of inflammation through the modulation of different signalling pathways, including those dependent on NF-κB and caspase-1-mediated cleavage of interleukin (IL)-1β and IL-18. A number of NLRs or NLR-associated proteins have been genetically associated with susceptibility to inflammatory bowel disease (IBD), either Crohn's disease or ulcerative colitis. Accordingly, recent studies have examined the role of NLR proteins in chemical-induced or bacteria-induced murine models of colitis.

Innate IL-17 and IL-22 responses to enteric bacterial pathogens.

With the identification of T helper (Th)17 cells, a specific subset of CD4 T cells expressing interleukin (IL)-17 and IL-22, research on the function of these cytokines initially largely focused on traditional adaptive immune responses. However, IL-17 and IL-22 enhance basic innate barrier defenses at mucosal surfaces, such as antimicrobial peptide production and neutrophil recruitment; both events that occur rapidly and precede adaptive phase immunity. At the intestinal mucosal surface, it is now clear that innate lymphoid cells are also important sources of IL-17 and IL-22 during early phases of infection.

Examining host-microbial interactions through the lens of NOD: From plants to mammals.

Nod-like receptors (NLRs) for detecting microbial invaders are features of many plant and animal families. Although broadly similar in form and function, intimate co-evolutionary events with environmental microbes have shaped specific classes of NLRs in different types of hosts. Details of the roles of different NLRs in signaling cellular immune responses to invading microbes are only beginning to emerge.

Acquisition of a multifunctional IgA+ plasma cell phenotype in the gut.

The largest mucosal surface in the body is in the gastrointestinal tract, a location that is heavily colonized by microbes that are normally harmless. A key mechanism required for maintaining a homeostatic balance between this microbial burden and the lymphocytes that densely populate the gastrointestinal tract is the production and transepithelial transport of poly-reactive IgA (ref. 1).

Nucleotide oligomerization domain-containing proteins instruct T cell helper type 2 immunity through stromal activation.

Although a number of studies have examined the development of T-helper cell type 2 (Th2) immunity in different settings, the mechanisms underlying the initiation of this arm of adaptive immunity are not well understood. We exploited the fact that immunization with antigen plus either nucleotide-binding oligomerization domain-containing proteins 1 (Nod1) or 2 (Nod2) agonists drives Th2 induction to understand how these pattern-recognition receptors mediate the development of systemic Th2 immune responses. Here, we show in bone-marrow chimeric mice that Nod1 and Nod2 expression within the stromal compartment is necessary for priming of effector CD4(+) Th2 responses and specific IgG1 antibodies.

Identification of an innate T helper type 17 response to intestinal bacterial pathogens.

Interleukin 17 (IL-17) is a central cytokine implicated in inflammation and antimicrobial defense. After infection, both innate and adaptive IL-17 responses have been reported, but the type of cells involved in innate IL-17 induction, as well as their contribution to in vivo responses, are poorly understood. Here we found that Citrobacter and Salmonella infection triggered early IL-17 production, which was crucial for host defense and was mediated by CD4(+) T helper cells.