Manipulating the EphB4-ephrinB2 axis to reduce metastasis in HNSCC.

The EphB4-ephrinB2 signaling axis has been heavily implicated in metastasis across numerous cancer types. Our emerging understanding of the dichotomous roles that EphB4 and ephrinB2 play in head and neck squamous cell carcinoma (HNSCC) poses a significant challenge to rational drug design. We find that EphB4 knockdown in cancer cells enhances metastasis in preclinical HNSCC models by augmenting immunosuppressive cells like T regulatory cells (Tregs) within the tumor microenvironment.

FMNL1 and mDia1 promote efficient T cell migration through complex environments via distinct mechanisms.

Lymphocyte trafficking and migration through tissues is critical for adaptive immune function and, to perform their roles, T cells must be able to navigate through diverse tissue environments that present a range of mechanical challenges. T cells predominantly express two members of the formin family of actin effectors, Formin-like 1 (FMNL1) and mammalian diaphanous-related formin 1 (mDia1). While both FMNL1 and mDia1 have been studied individually, they have not been directly compared to determine functional differences in promoting T cell migration.

OpenSTED: open-source dynamic intensity minimum system for stimulated emission depletion microscopy.

Significance: Stimulated emission depletion (STED) is a powerful super-resolution microscopy technique that can be used for imaging live cells. However, the high STED laser powers can cause significant photobleaching and sample damage in sensitive biological samples. The dynamic intensity minimum (DyMIN) technique turns on the STED laser only in regions of the sample where there is fluorescence signal, thus saving significant sample photobleaching.

Ena/VASP Protein-Mediated Actin Polymerization Contributes to Naïve CD8 T Cell Activation and Expansion by Promoting T Cell-APC Interactions .

Naïve T cell activation in secondary lymphoid organs such as lymph nodes (LNs) occurs upon recognition of cognate antigen presented by antigen presenting cells (APCs). T cell activation requires cytoskeleton rearrangement and sustained interactions with APCs. Enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) proteins are a family of cytoskeletal effector proteins responsible for actin polymerization and are frequently found at the leading edge of motile cells.

LPA suppresses T cell function by altering the cytoskeleton and disrupting immune synapse formation.

Cancer and chronic infections often increase levels of the bioactive lipid, lysophosphatidic acid (LPA), that we have demonstrated acts as an inhibitory ligand upon binding LPAR5 on CD8 T cells, suppressing cytotoxic activity and tumor control. This study, using human and mouse primary T lymphocytes, reveals how LPA disrupts antigen-specific CD8 T cell:target cell immune synapse (IS) formation and T cell function via competing for cytoskeletal regulation. Specifically, we find upon antigen-specific T cell:target cell formation, IP3R1 localizes to the IS by a process dependent on mDia1 and actin and microtubule polymerization.

Autoimmunity in motion: Mechanisms of immune regulation and destruction revealed by in vivo imaging.

Autoimmunity arises when mechanisms of immune tolerance fail. Here we discuss mechanisms of T cell activation and tolerance and the dynamics of the autoimmune response at the site of disease. Live imaging of autoimmunity provides the ability to analyze immune cell dynamics at the single-cell level within the complex intact environment where disease occurs.

MERTK on mononuclear phagocytes regulates T cell antigen recognition at autoimmune and tumor sites.

Understanding mechanisms of immune regulation is key to developing immunotherapies for autoimmunity and cancer. We examined the role of mononuclear phagocytes during peripheral T cell regulation in type 1 diabetes and melanoma. MERTK expression and activity in mononuclear phagocytes in the pancreatic islets promoted islet T cell regulation, resulting in reduced sensitivity of T cell scanning for cognate antigen in prediabetic islets.

Polymerization power: effectors of actin polymerization as regulators of T lymphocyte migration through complex environments.

During their life span, T cells are tasked with patrolling the body for potential pathogens. To do so, T cells migrate through numerous distinct anatomical sites and tissue environments with different biophysical characteristics. To migrate through these different environments, T cells use various motility strategies that rely on actin network remodeling to generate shape changes and mechanical forces.

Impact of HIV-1 Infection and Antigen Class on T Follicular Helper Cell Responses to Pneumococcal Polysaccharide-Protein Conjugate Vaccine-13.

Pneumococcal infections are common and serious complications of HIV-1 disease. Prevention has been compromised by the limited magnitude and quality of Ab responses to T cell-independent type 2 pneumococcal capsular polysaccharides (PPS). The pneumococcal polysaccharide-protein conjugate vaccine-13 (PCV-13) contains PPS conjugated to the T cell-dependent protein (diphtheria toxoid [DT] [CRM197]).

Formin-like 1 mediates effector T cell trafficking to inflammatory sites to enable T cell-mediated autoimmunity.

Lymphocyte migration is essential for the function of the adaptive immune system, and regulation of T cell entry into tissues is an effective therapy in autoimmune diseases. Little is known about the specific role of cytoskeletal effectors that mediate mechanical forces and morphological changes essential for migration in complex environments. We developed a new Formin-like-1 (FMNL1) knock-out mouse model and determined that the cytoskeletal effector FMNL1 is selectively required for effector T cell trafficking to inflamed tissues, without affecting naïve T cell entry into secondary lymphoid organs.

Immune cell trafficking to the islets during type 1 diabetes.

Inhibition of immune cell trafficking to the pancreatic islets during type 1 diabetes (T1D) has therapeutic potential, since targeting of T cell and B cell trafficking has been clinically effective in other autoimmune diseases. Trafficking to the islets is characterized by redundancy in adhesion molecule and chemokine usage, which has not enabled effective targeting to date. Additionally, cognate antigen is not consistently required for T cell entry into the islets throughout the progression of disease.

CD11c Cells Are Gatekeepers for Lymphocyte Trafficking to Infiltrated Islets During Type 1 Diabetes.

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease that affects more than 19 million people with incidence increasing rapidly worldwide. For T cells to effectively drive T1D, they must first traffic to the islets and extravasate through the islet vasculature. Understanding the cues that lead to T cell entry into inflamed islets is important because diagnosed T1D patients already have established immune infiltration of their islets.

The Formin mDia1 Regulates Acute Lymphoblastic Leukemia Engraftment, Migration, and Progression .

Leukemias typically arise in the bone marrow and then spread to the blood and into other tissues. To disseminate into tissues, leukemia cells migrate into the blood stream and then exit the circulation by migrating across vascular endothelial barriers. Formin proteins regulate cytoskeletal remodeling and cell migration of normal and malignant cells.

Live Imaging of IL-4-Expressing T Follicular Helper Cells in Explanted Lymph Nodes.

The generation of class-switched, high-affinity, antibody-producing B cells plays a critical role in the establishment of type 2 immunity to intestinal helminths as well as in the pathogenesis of allergy and asthma. The generation of these high-affinity, antibody-producing B cells occurs in germinal centers (GC) and relies on interactions with follicular dendritic cells (FDCs) and T follicular helper (Tfh) cells. One critical mediator produced by Tfh cells in GCs is interleukin-4 (IL-4).

Ena/VASP proteins regulate activated T-cell trafficking by promoting diapedesis during transendothelial migration.

Vasodilator-stimulated phosphoprotein (VASP) and Ena-VASP-like (EVL) are cytoskeletal effector proteins implicated in regulating cell morphology, adhesion, and migration in various cell types. However, the role of these proteins in T-cell motility, adhesion, and in vivo trafficking remains poorly understood. This study identifies a specific role for EVL and VASP in T-cell diapedesis and trafficking.

Perinuclear Arp2/3-driven actin polymerization enables nuclear deformation to facilitate cell migration through complex environments.

Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions.

Myosin-IIA regulates leukemia engraftment and brain infiltration in a mouse model of acute lymphoblastic leukemia.

Leukemia dissemination (the spread of leukemia cells from the bone marrow) and relapse are associated with poor prognosis. Often, relapse occurs in peripheral organs, such as the CNS, which acts as a sanctuary site for leukemia cells to escape anti-cancer treatments. Similar to normal leukocyte migration, leukemia dissemination entails migration of cells from the blood circulation into tissues by extravasation.

Flow Cytometric Analysis of Mononuclear Phagocytes in Nondiseased Human Lung and Lung-Draining Lymph Nodes.

Rationale: The pulmonary mononuclear phagocyte system is a critical host defense mechanism composed of macrophages, monocytes, monocyte-derived cells, and dendritic cells. However, our current characterization of these cells is limited because it is derived largely from animal studies and analysis of human mononuclear phagocytes from blood and small tissue resections around tumors.

Objectives: Phenotypic and morphologic characterization of mononuclear phagocytes that potentially access inhaled antigens in human lungs.

Cell migration and antigen capture are antagonistic processes coupled by myosin II in dendritic cells.

The immune response relies on the migration of leukocytes and on their ability to stop in precise anatomical locations to fulfil their task. How leukocyte migration and function are coordinated is unknown. Here we show that in immature dendritic cells, which patrol their environment by engulfing extracellular material, cell migration and antigen capture are antagonistic.

CD11c-Expressing B Cells Are Located at the T Cell/B Cell Border in Spleen and Are Potent APCs.

In addition to the secretion of Ag-specific Abs, B cells may play an important role in the generation of immune responses by efficiently presenting Ag to T cells. We and other investigators recently described a subpopulation of CD11c(+) B cells (Age/autoimmune-associated B cells [ABCs]) that appear with age, during virus infections, and at the onset of some autoimmune diseases and participate in autoimmune responses by secreting autoantibodies. In this study, we assessed the ability of these cells to present Ag and activate Ag-specific T cells.

Antigen recognition in the islets changes with progression of autoimmune islet infiltration.

In type 1 diabetes, the pancreatic islets are an important site for therapeutic intervention because immune infiltration of the islets is well established at diagnosis. Therefore, understanding the events that underlie the continued progression of the autoimmune response and islet destruction is critical. Islet infiltration and destruction is an asynchronous process, making it important to analyze the disease process on a single islet basis.

An evolving autoimmune microenvironment regulates the quality of effector T cell restimulation and function.

Defining the processes of autoimmune attack of tissues is important for inhibiting continued tissue destruction. In type 1 diabetes, it is not known how cytotoxic effector T cell responses evolve over time in the pancreatic islets targeted for destruction. We used two-photon microscopy of live, intact, individual islets to investigate how progression of islet infiltration altered the behavior of infiltrating islet-specific CD8(+) T cells.