Automation of the Micronucleus Assay Using Imaging Flow Cytometry and Artificial Intelligence.

The micronucleus (MN) assay is used worldwide by regulatory bodies to evaluate chemicals for genetic toxicity. The assay can be performed in two ways: by scoring MN in once-divided, cytokinesis-blocked binucleated cells or fully divided mononucleated cells. Historically, light microscopy has been the gold standard method to score the assay, but it is laborious and subjective.

Unaltered levels of transplant arteriosclerosis in the absence of the B cell homing chemokine receptor CXCR5.

Chemokine receptors and their ligands are crucial for lymphocyte trafficking under both homeostatic and inflammatory conditions. The chemokine receptor CXCR5 controls B cell migration and the organization of B cell follicles. The aim of this study was to investigate the impact of CXCR5 on the development of transplant arteriosclerosis.

Increased transplant arteriosclerosis in the absence of CCR7 is associated with reduced expression of Foxp3.

Background: The chemokine receptor CCR7 plays a pivotal role in the homing of naïve T cells and regulatory T cells to secondary lymphoid organs and the migration of dendritic cells into afferent lymphatic vessels. Antigen presentation, T cell recruitment, and expansion of regulatory cells are crucial events in establishing and controlling chronic allograft dysfunction. In this study, we report an important role for chemokine receptor CCR7 in the development of transplant arteriosclerosis.

Genetic variants of chemokine receptor CCR7 in patients with systemic lupus erythematosus, Sjogren's syndrome and systemic sclerosis.

Background: The chemokine receptor CCR7 is a key organizer of the immune system. Gene targeting in mice revealed that Ccr7-deficient animals are severely impaired in the induction of central and peripheral tolerance. Due to these defects, Ccr7-deficient mice spontaneously develop multi-organ autoimmunity showing symptoms similar to those observed in humans suffering from connective tissue autoimmune diseases.

Regulatory T cells interfere with the development of bronchus-associated lymphoid tissue.

Presence and extent of bronchus-associated lymphoid tissue (BALT) is subject to considerable variations between species and is only occasionally observed in lungs of mice. Here we demonstrate that mice deficient for the chemokine receptor CCR7 regularly develop highly organized BALT. These structures were not present at birth but were detectable from day 5 onwards.

Induction of tolerance to innocuous inhaled antigen relies on a CCR7-dependent dendritic cell-mediated antigen transport to the bronchial lymph node.

Allergic airway diseases such as asthma are caused by a failure of the immune system to induce tolerance against environmental Ags. The underlying molecular and cellular mechanisms that initiate tolerance are only partly understood. In this study, we demonstrated that a CCR7-dependent migration of both CD103+ and CD103- lung dendritic cells (DC) to the bronchial lymph node (brLN) is indispensable for this process.

Transcoronary delivery of bone marrow cells to the infarcted murine myocardium: feasibility, cellular kinetics, and improvement in cardiac function.

Efficient strategies for labelling and delivery of bone marrow derived stem cells (BMCs) are required to elucidate the cellular kinetics and therapeutic effects after BMC transfer for myocardial infarction (MI). Lineage negative (lin-) BMCs, labelled ex vivo in a simple procedure with the cell tracker dye tetramethyl-rhodamine (TAMRA), were reliably detected by fluorescence microscopy with higher specificity than retroviral enhanced green fluorescence protein (EGFP) marking and detection. Only few cells entered the ischemic myocardium after intravenous (i.

Balanced expression of CXCR5 and CCR7 on follicular T helper cells determines their transient positioning to lymph node follicles and is essential for efficient B-cell help.

The production of high-affinity antibodies to T-dependent antigens requires the interaction of B cells and T helper cells expressing receptors specific for the same antigen. Although several mechanisms have been elucidated that regulate B-cell trafficking within lymphoid organs, less is known about molecular cues that guide the small subpopulation of CD4+ follicular T helper cells to B-cell follicles. Using adoptive transfer of transgenic T cells in mice, we demonstrate that antigen-induced activation leads to a finely tuned positioning of T cells either to the T-cell area or the B-cell follicle.

CCR7 governs skin dendritic cell migration under inflammatory and steady-state conditions.

The CC chemokine receptor CCR7 has been identified as a key regulator of homeostatic B and T cell trafficking to secondary lymphoid organs. Data presented here demonstrate that CCR7 is also an essential mediator for entry of both dermal and epidermal dendritic cells (DC) into the lymphatic vessels within the dermis while this receptor is dispensable for the mobilization of Langerhans cells from the epidermis to the dermis. Moreover, a distinct population of CD11c(+)MHCII(high) DC showing low expression of the costimulatory molecules CD40, CD80, and CD86 in wild-type animals was virtually absent in skin-draining lymph nodes of CCR7-deficient mice under steady-state conditions.

Thymic T cell development and progenitor localization depend on CCR7.

T cell differentiation in the adult thymus depends on sequential interactions between lymphoid progenitors and stromal cells found in distinct regions of the cortex and medulla. Therefore, migration of T cell progenitors through distinct stromal environments seems to be a crucial process regulating differentiation and homeostasis inside the thymus. Here we show that CCR7-deficient mice are distinguished by a disturbed thymic architecture, impaired T cell development, and decreased numbers of the thymocytes.

Ectopic expression of CCL19 impairs alloimmune response in mice.

Initiation of an antitumour immune response is characterized by a complex process of chemokine-mediated cell migration and cell-cell interactions. Overexpression of chemokine CCL19 in tumour cells has been shown to result in accelerated tumour rejection under certain experimental conditions, suggesting a novel approach in the therapy of neoplastic malignancies. To investigate CCL19-mediated modulations of cellular immune responses in vivo, we generated a chimeric CCL19-immunoglobulin G2b (IgG2b) Fc fusion protein, which binds to the chemokine receptor CCR7 comparable to native CCL19.

Chemokines as organizers of primary and secondary lymphoid organs.

Lymphoid organs represent highly specialized tissues enabling the development and activation of B and T lymphocytes. Contact between lymphoid and parenchymal cells in bone marrow and thymus is a prerequisite for proper development of B and T cells, respectively, while secondary lymphoid organs, such as spleen and lymph nodes are the places where B and T cells get into contact with antigen presenting cells in order to initiate an adaptive immune response. Recent evidence suggests that few constitutively produced chemokines are essentially required to allow for the correct positioning and interaction of lymphoid and non-lymphoid cells thus creating microenvironments for efficient development and activation of the immune system at multiple stages.

Chemokine receptor CCR9 contributes to the localization of plasma cells to the small intestine.

Humoral immunity in the gut-associated lymphoid tissue is characterized by the production of immunoglobulin A (IgA) by antibody-secreting plasma cells (PCs) in the lamina propria. The chemokine CCL25 is expressed by intestinal epithelial cells and is capable of inducing chemotaxis of IgA+ PCs in vitro. Using a newly generated monoclonal antibody against murine CCR9, we show that IgA+ PCs express high levels of CCR9 in the mesenteric lymph node (MLN) and Peyer's patches (PPs), but down-regulate CCR9 once they are located in the small intestine.

Cooperating mechanisms of CXCR5 and CCR7 in development and organization of secondary lymphoid organs.

Homeostatic chemokines participate in the development of secondary lymphoid organs and later on in the functional organization of these tissues. The development of lymph nodes (LNs) and Peyer's patches depends on the recruitment of CD3- CD4+ interleukin (IL)-7R alpha hi cells to sites of future organ development. CD3- CD4+ IL-7R alpha hi cells express the chemokine receptor CXCR5 and might be attracted by its ligand CXCL13, which is secreted by mesenchymal cells.

Balanced responsiveness to chemoattractants from adjacent zones determines B-cell position.

B lymphocytes re-circulate between B-cell-rich compartments (follicles or B zones) in secondary lymphoid organs, surveying for antigen. After antigen binding, B cells move to the boundary of B and T zones to interact with T-helper cells. Despite the importance of B--T-cell interactions for the induction of antibody responses, the mechanism causing B-cell movement to the T zone has not been defined.