Highlights d Mycobacterial granulomas contain a subpopulation of VEGF-A-producing macrophages d VEGF-A recruits macrophages to the granuloma via a nonangiogenic pathway d VEGF-A inhibition reduces granulomatous inflammation with limited effect on protection d Mice with myeloid-specific deletion of VEGF-A are more resistant to Mtb infection

Meningeal lymphatic vessels residing in the dural layer above the sinuses of the brain, meninges at the base of the brain, and near the cribriform plate have all been shown to drain fluid, cells, and antigens. We have previously reported that meningeal lymphatics near the cribriform plate undergo VEGFR3-dependent lymphangiogenesis during experimental autoimmune encephalomyelitis (EAE) to facilitate excess drainage. Using single-cell RNA sequencing (scRNA-seq), we report that neuroinflammation changes the phenotype and function of cribriform plate lymphatic endothelial cells (cpLECs). Upregulation of genes involved in antigen presentation, adhesion to leukocytes, and immunoregulatory molecules were verified by flow cytometry and functional assays.The inflamed cpLECs retain dendritic cells and to lesser extent CD4 T cells, creating an immune-regulatory niche that represents a previously underappreciated interface in the regulation of neuroinflammation. Additionally, the discontinuity of the arachnoid membrane near cpLECs provides unrestricted access to the cerebrospinal fluid (CSF) for immune surveillance. These findings may lead to new therapeutic approaches to neuroinflammatory diseases.

Summary Systemic lupus erythematosus is a chronic inflammatory disease which involves multiple organs. Self‐specific B and T cells play a main role in the pathogenesis of lupus and have been defined as a logical target for selective therapy. The protein annexin A1 (ANX A1) is a modulator of the immune system involving many cell types. An abnormal expression of ANX A1 was found on activated B and T cells during autoimmunity, suggesting its importance as a potential therapeutic target. We hypothesize that it may be possible to down‐regulate the activity of autoreactive T and B cells from lupus patients in a humanized immunodeficient mouse model by treating them with an antibody against ANX A1. When cultured in the presence of anti‐ANX A1, peripheral blood mononuclear cells (PBMC) from lupus patients showed a decreased number of immunoglobulin (Ig)G anti‐dsDNA antibody‐secreting plasma cells, decreased T cell proliferation and expression of activation markers and increased B and T cell apoptosis. We employed a humanized model of SLE by transferring PBMCs from lupus patients to immunodeficient non‐obese diabetic‐severe combined immunodeficient (NOD‐SCID) mice. The humanized animals presented autoantibodies, proteinuria and immunoglobulin deposition in the renal glomeruli. Treatment of these NOD‐SCID mice with an anti‐ANX A1 antibody prevented appearance of anti‐DNA antibodies and proteinuria, while the phosphate‐buffered saline (PBS)‐injected animals had high levels after the transfer. The treatment reduced the levels of autoantibodies to several autoantigens, lupus‐associated cytokines and disease symptoms.

Systemic lupus erythematosus (SLE) is a polygenic pathological disorder which involves multiple organs. Self-specific B cells play a main role in the lupus pathogenesis by generating autoantibodies as well as by serving as important autoantigen-presenting cells. Autoreactive T lymphocytes, on the other hand, are responsible for B cell activation and proliferation, and cytokine production. Therefore, both factors promote the idea that a down-modulation of activated self-reactive T and B cells involved in the pathogenic immune response is a reasonable approach for SLE therapy. Annexin A1 (ANX A1) is expressed by many cell types and binds to phospholipids in a Ca dependent manner. Abnormal expression of ANX A1 was found on activated B and T cells in both murine and human autoimmunity, suggesting its potential role as a therapeutic target. While its role on T lymphocytes is through formyl peptide receptor-like molecules (FPRL), and the formed ANX A1/FPRL pathway modulates T cell receptor signalling, there is still no fool-proof data available for the role of ANX A1 in B cells. We employed a lupus model of Balb/c mice with pristane-induced SLE which very closely resembles human lupus. In the present study, we investigated the possibility to modulate the autoimmune response in a pristane-induced mouse model of SLE using an anti- ANX A1 antibody. Administration of this monoclonal antibody resulted in the inhibition of T-cell activation and proliferation, suppression of IgG anti-dsDNA antibody-secreting plasma cells and of proteinuria, decreased disease activity and prolonged survival compared to control group.

Protein microarray technology is becoming the method of choice for identifying protein interaction partners, detecting specific proteins, carbohydrates and lipids, or for characterizing protein interactions and serum antibodies in a massively parallel manner. Availability of the well-established instrumentation of DNA arrays and development of new fluorescent detection instruments promoted the spread of this technique. Fluorescent detection has the advantage of high sensitivity, specificity, simplicity and wide dynamic range required by most measurements. Fluorescence through specifically designed probes and an increasing variety of detection modes offers an excellent tool for such microarray platforms. Measuring for example the level of antibodies, their isotypes and/or antigen specificity simultaneously can offer more complex and comprehensive information about the investigated biological phenomenon, especially if we take into consideration that hundreds of samples can be measured in a single assay. Not only body fluids, but also cell lysates, extracted cellular components, and intact living cells can be analyzed on protein arrays for monitoring functional responses to printed samples on the surface. As a rapidly evolving area, protein microarray technology offers a great bulk of information and new depth of knowledge. These are the features that endow protein arrays with wide applicability and robust sample analyzing capability. On the whole, protein arrays are emerging new tools not just in proteomics, but glycomics, lipidomics, and are also important for immunological research. In this review we attempt to summarize the technical aspects of planar fluorescent microarray technology along with the description of its main immunological applications.

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In vitro culture models of the blood-brain barrier (BBB) provide a useful platform to test the mechanisms of cellular infiltration and pathogen dissemination into the central nervous system (CNS). We present an in vitro mouse model of the BBB to test Mycobacterium tuberculosis (Mtb) dissemination across brain endothelial cells. One-third of the global population is infected with Mtb, and in 1%-2% of cases bacteria invade the CNS through a largely unknown process. The "Trojan horse" theory supports the role of a cellular carrier that engulfs bacteria and carries them to the brain without being recognized. We present for the first time a protocol for an in vitro BBB-granuloma model that supports the Trojan horse mechanism of Mtb dissemination into the CNS. Handling of bacterial cultures, in vivo and in vitro infections, isolation of primary astroglial and endothelial cells, and assembly of the in vitro BBB model is presented. These techniques can be used to analyze the interaction of adaptive and innate immune system cells with brain endothelial cells, cellular transmigration, BBB morphological and functional changes, and methods of bacterial dissemination.