Immune cell migration as a means to control immune privilege: lessons from the CNS and tumors

An agent-based method to estimate 3D cell migration trajectories from 2D measurements: Quantifying and comparing T vs CAR-T 3D cell migration

BACKGROUND AND OBJECTIVE

Immune cell migration is one of the key features that enable immune cells to find invading pathogens, control tissue damage, and eliminate primary developing tumors. Chimeric antigen receptor (CAR) T-cell therapy is a novel strategy in the battle against various cancers. It has been successful in treating hematological tumors, yet it still faces many challenges in the case of solid tumors. In this work, we evaluate the three-dimensional (3D) migration capacity of T and CAR-T cells within dense collagen-based hydrogels. Quantifying three-dimensional (3D) cell migration requires microscopy techniques that may not be readily accessible. Thus, we introduce a straightforward mathematical model designed to infer 3D trajectories of cells from two-dimensional (2D) cell trajectories.

METHODS

We develop a 3D agent-based model (ABM) that simulates the temporal changes in the direction of migration with an inverse transform sampling method. Then, we propose an optimization procedure to accurately orient cell migration over time to reproduce cell migration from 2D experimental cell trajectories. With this model, we simulate cell migration assays of T and CAR-T cells in microfluidic devices conducted under hydrogels with different concentrations of type I collagen and validate our 3D cell migration predictions with light-sheet microscopy.

RESULTS

Our findings indicate that CAR-T cell migration is more sensitive to collagen concentration increases than T cells, resulting in a more pronounced reduction in their invasiveness. Moreover, our computational model reveals significant differences in 3D movement patterns between T and CAR-T cells. T cells exhibit migratory behavior in 3D whereas that CAR-T cells predominantly move within the XY plane, with limited movement in the Z direction. However, upon the introduction of a CXCL12 chemical gradient, CAR-T cells present migration patterns that closely resemble those of T cells.

CONCLUSIONS

This framework demonstrates that 2D projections of 3D trajectories may not accurately represent real migration patterns. Moreover, it offers a tool to estimate 3D migration patterns from 2D experimental data, which can be easily obtained with automatic quantification algorithms. This approach helps reduce the need for sophisticated and expensive microscopy equipment required in laboratories, as well as the computational burden involved in producing and analyzing 3D experimental data.

Streptococcus pneumoniae meningitis and the CNS barriers

Streptococcus pneumoniae (SPN) is a globally significant cause of meningitis, the pathophysiology of which involves damage to the brain by both bacterial virulence factors and the host inflammatory response. In most cases of SPN meningitis bacteria translocate from the blood into the central nervous system (CNS). The principal site of SPN translocation into the CNS is not known, with possible portals of entry proposed to be the cerebral or meningeal blood vessels or the choroid plexus. All require SPN to bind to and translocate across the vascular endothelial barrier, and subsequently the basement membrane and perivascular structures, including an additional epithelial barrier in the case of the blood-CSF barrier. The presence of SPN in the CNS is highly inflammatory resulting in marked neutrophilic infiltration. The secretion of toxic inflammatory mediators by activated neutrophils within the CNS damages pathogen and host alike, including the non-replicative neurons which drives morbidity and mortality. As with the translocation of SPN, the recruitment of neutrophils into the CNS in SPN meningitis necessitates the translocation of neutrophils from the circulation across the vascular barrier, a process that is tightly regulated under basal conditions - a feature of the 'immune specialization' of the CNS. The brain barriers are therefore central to SPN meningitis, both through a failure to exclude bacteria and maintain CNS sterility, and subsequently through the active recruitment and/or failure to exclude circulating leukocytes. The interactions of SPN with these barriers, barrier inflammatory responses, along with their therapeutic implications, are explored in this review.

Immune System Influence on Hematopoietic Stem Cells and Leukemia Development

Hematopoietic stem cells (HSCs) are the source for all blood cells, including immune cells, and they interact dynamically with the immune system. This chapter will explore the nature of stem cells, particularly HSCs, in the context of their immune microenvironment. The dynamic interactions between stem cells and the immune system can have profound implications for current and future therapies, particularly regarding a potential "immune-privileged" HSC microenvironment. Immune/stem cell interactions change during times of stress and injury. Recent advances in cancer immunotherapy have overturned the long-standing belief that, being derived from the self, cancer cells should be immunotolerant. Instead, an immunosurveillance system recognizes and eliminates emergent pre-cancerous cells. Only in the context of a failing immunosurveillance system does cancer fully develop. Combined with the knowledge that stem cells or their unique properties can be critically important for cancer initiation, persistence, and resistance to therapy, understanding the unique immune properties of stem cells will be critical for the development of future cancer therapies. Accordingly, the therapeutic implications for leukemic stem cells (LSCs) inheriting an immune-privileged state from HSCs will be discussed. Through their dynamic interactions with a diverse immune system, stem cells serve as the light and dark root of cancer prevention vs. development.

Trypanosoma brucei rhodesiense Inhibitor of Cysteine Peptidase (ICP) Is Required for Virulence in Mice and to Attenuate the Inflammatory Response

The protozoan Trypanosoma brucei rhodesiense causes Human African Trypanosomiasis, also known as sleeping sickness, and penetrates the central nervous system, leading to meningoencephalitis. The Cathepsin L-like cysteine peptidase of T. b. rhodesiense has been implicated in parasite penetration of the blood-brain barrier and its activity is modulated by the chagasin-family endogenous inhibitor of cysteine peptidases (ICP). To investigate the role of ICP in T. b. rhodesiense bloodstream form, ICP-null (Δicp) mutants were generated, and lines re-expressing ICP (Δicp:ICP). Lysates of Δicp displayed increased E-64-sensitive cysteine peptidase activity and the mutant parasites traversed human brain microvascular endothelial cell (HBMEC) monolayers in vitro more efficiently. Δicp induced E-selectin in HBMECs, leading to the adherence of higher numbers of human neutrophils. In C57BL/6 mice, no Δicp parasites could be detected in the blood after 6 days, while mice infected with wild-type (WT) or Δicp:ICP displayed high parasitemia, peaking at day 12. In mice infected with Δicp, there was increased recruitment of monocytes to the site of inoculation and higher levels of IFN-γ in the spleen. At day 14, mice infected with Δicp exhibited higher preservation of the CD4+, CD8+, and CD19+ populations in the spleen, accompanied by sustained high IFN-γ, while NK1.1+ populations receded nearly to the levels of uninfected controls. We propose that ICP helps to downregulate inflammatory responses that contribute to the control of infection.

Credibility of the Neutrophil-to-Lymphocyte Count Ratio in Severe Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of morbidity and mortality worldwide. The consequences of a TBI generate the activation and accumulation of inflammatory cells. The peak number of neutrophils entering into an injured brain is observed after 24 h; however, cells infiltrate within 5 min of closed brain injury. Neutrophils release toxic molecules including free radicals, proinflammatory cytokines, and proteases that advance secondary damage. Regulatory T cells impair T cell infiltration into the central nervous system and elevate reactive astrogliosis and interferon-γ gene expression, probably inducing the process of healing. Therefore, the neutrophil-to-lymphocyte ratio (NLR) may be a low-cost, objective, and available predictor of inflammation as well as a marker of secondary injury associated with neutrophil activation. Recent studies have documented that an NLR value on admission might be effective for predicting outcome and mortality in severe brain injury patients.

Transmigration across a Steady-State Blood-Brain Barrie Induces Activation of Circulating Dendritic Cells Partly Mediated by Actin Cytoskeletal Reorganization

The central nervous system (CNS) is considered to be an immunologically unique site, in large part given its extensive protection by the blood–brain barrier (BBB). As our knowledge of the complex interaction between the peripheral immune system and the CNS expands, the mechanisms of immune privilege are being refined. Here, we studied the interaction of dendritic cells (DCs) with the BBB in steady–state conditions and observed that transmigrated DCs display an activated phenotype and stronger T cell-stimulatory capacity as compared to non-migrating DCs. Next, we aimed to gain further insights in the processes underlying activation of DCs following transmigration across the BBB. We investigated the interaction of DCs with endothelial cells as well as the involvement of actin cytoskeletal reorganization. Whereas we were not able to demonstrate that DCs engulf membrane fragments from fluorescently labelled endothelial cells during transmigration across the BBB, we found that blocking actin restructuring of DCs by latrunculin-A significantly impaired in vitro migration of DC across the BBB and subsequent T cell-stimulatory capacity, albeit no effect on migration-induced phenotypic activation could be demonstrated. These observations contribute to the current understanding of the interaction between DCs and the BBB, ultimately leading to the design of targeted therapies capable to inhibit autoimmune inflammation of the CNS.

Single-Cell Omics in Dissecting Immune Microenvironment of Malignant Gliomas-Challenges and Perspectives

Single-cell technologies allow precise identification of tumor composition at the single-cell level, providing high-resolution insights into the intratumoral heterogeneity and transcriptional activity of cells in the tumor microenvironment (TME) that previous approaches failed to capture. Malignant gliomas, the most common primary brain tumors in adults, are genetically heterogeneous and their TME consists of various stromal and immune cells playing an important role in tumor progression and responses to therapies. Previous gene expression or immunocytochemical studies of immune cells infiltrating TME of malignant gliomas failed to dissect their functional phenotypes. Single-cell RNA sequencing (scRNA-seq) and cytometry by time-of-flight (CyTOF) are powerful techniques allowing quantification of whole transcriptomes or >30 protein targets in individual cells. Both methods provide unprecedented resolution of TME. We summarize the findings from these studies and the current state of knowledge of a functional diversity of immune infiltrates in malignant gliomas with different genetic alterations. A precise definition of functional phenotypes of myeloid and lymphoid cells might be essential for designing effective immunotherapies. Single-cell omics studies have identified crucial cell subpopulations and signaling pathways that promote tumor progression, influence patient survival or make tumors vulnerable to immunotherapy. We anticipate that the widespread usage of single-cell omics would allow rational design of oncoimmunotherapeutics.

Glioma escape signature and clonal development under immune pressure

Immunotherapeutic strategies are increasingly important in neuro-oncology, and the elucidation of escape mechanisms that lead to treatment resistance is crucial. We investigated the impact of immune pressure on the clonal dynamics and immune escape signature by comparing glioma growth in immunocompetent versus immunodeficient mice. Glioma-bearing WT and Pd-1-/- mice survived significantly longer than immunodeficient Pfp-/- Rag2-/- mice. While tumors in Pfp-/- Rag2-/- mice were highly polyclonal, immunoedited tumors in WT and Pd-1-/- mice displayed reduced clonality with emergence of immune escape clones. Tumor cells in WT mice were distinguished by an IFN-γ-mediated response signature with upregulation of genes involved in immunosuppression. Tumor-infiltrating stromal cells, which include macrophages/microglia, contributed even more strongly to the immunosuppressive signature than the actual tumor cells. The identified murine immune escape signature was reflected in human patients and correlated with poor survival. In conclusion, immune pressure profoundly shapes the clonal composition and gene regulation in malignant gliomas.

Poor efficacy of anti-programmed cell death-1/ligand 1 monotherapy for non-small cell lung cancer patients with active brain metastases

BACKGROUND

The efficacy of anti-programmed cell death-1/ligand 1 antibody monotherapy (anti-PD-1/PD-L1 monotherapy) in patients with active brain metastases (BMs) is not established. Here, we aimed to evaluate the efficacy of anti-PD-1/PD-L1 monotherapy in non-small cell lung cancer (NSCLC) patients with active BMs.

METHODS

This retrospective study included NSCLC patients treated with second-line or later-line anti-PD-1/PD-L1 monotherapy between December 2015 and August 2019. Patients were classified into those with or without active BMs, including symptomatic BMs requiring systemic steroids and untreated BMs. The progression-free survival (PFS) and overall survival (OS) of the patients with and without active BMs were compared. Intracranial and extracranial tumor responses were evaluated in patients with active BMs.

RESULTS

We analyzed 197 patients who had received anti-PD-1/PD-L1 monotherapy. Among them, 24 had active BMs. Among those without active BMs, 145 had no BMs and 28 had treated asymptomatic BMs. The PFS and OS of patients with active BMs were significantly shorter than those of patients without active BMs (1.3 vs. 2.7 months; P < 0.001, and 4.5 vs. 16.3 months; P = 0.001 respectively). For patients with active BMs, the intracranial and extracranial response rates were 13.3% and 26.7%, respectively. On multivariate analysis, active BMs, poor performance status (PS), and EGFR/ALK positivity were significant factors associated with shorter PFS. Active BMs and poor PS were significant factors associated with shorter OS.

CONCLUSIONS

This study suggested that anti-PD-1/PD-L1 monotherapy was not effective for NSCLC patients with active BMs. Further studies on immunotherapy are needed for patients with active BMs.

KEY POINTS

Significant findings of the study: The present study showed that anti-PD-1/PD-L1 antibody monotherapy was not effective for non-small cell lung cancer patients with active brain metastases. Intracranial and extracranial response rates were 13.3% and 26.7%, respectively.

WHAT THIS STUDY ADDS

Further studies on immunotherapy are needed for patients with active BMs.

Tumor mechanisms of resistance to immune attack

The immune system plays a key role in the interactions between host and tumor. Immune selection pressure is a driving force behind the sculpting and evolution of malignant cancer cells to escape this immune attack. Several common tumor cell-based mechanisms of resistance to immune attack have been identified and can be broadly categorized into three main classes: loss of antigenicity, loss of immunogenicity, and creation of an immunosuppressive microenvironment. In this review, we will discuss in detail the relevant literature associated with each class of resistance and will describe the relevance of these mechanisms to human cancer patients. To conclude, we will outline the implications these mechanisms have for the treatment of cancer using currently available therapeutic approaches. Immunotherapy has been a successful addition to current treatment approaches, but many patients either do not respond or quickly become resistant. This reflects the ability of tumors to continue to adapt to immune selection pressure at all stages of development. Additional study of immune escape mechanisms and immunotherapy resistance mechanisms will be needed to inform future treatment approaches.

T Lymphocytes as Measurable Targets of Protection and Vaccination Against Viral Disorders

Continuous epidemiological surveillance of existing and emerging viruses and their associated disorders is gaining importance in light of their abilities to cause unpredictable outbreaks as a result of increased travel and vaccination choices by steadily growing and aging populations. Close surveillance of outbreaks and herd immunity are also at the forefront, even in industrialized countries, where previously eradicated viruses are now at risk of re-emergence due to instances of strain recombination, contractions in viral vector geographies, and from their potential use as agents of bioterrorism. There is a great need for the rational design of current and future vaccines targeting viruses, with a strong focus on vaccine targeting of adaptive immune effector memory T cells as the gold standard of immunity conferring long-lived protection against a wide variety of pathogens and malignancies. Here, we review viruses that have historically caused large outbreaks and severe lethal disorders, including respiratory, gastric, skin, hepatic, neurologic, and hemorrhagic fevers. To observe trends in vaccinology against these viral disorders, we describe viral genetic, replication, transmission, and tropism, host-immune evasion strategies, and the epidemiology and health risks of their associated syndromes. We focus on immunity generated against both natural infection and vaccination, where a steady shift in conferred vaccination immunogenicity is observed from quantifying activated and proliferating, long-lived effector memory T cell subsets, as the prominent biomarkers of long-term immunity against viruses and their associated disorders causing high morbidity and mortality rates.

Matrix metalloproteinase-9 activity and a downregulated Hedgehog pathway impair blood-brain barrier function in an in vitro model of CNS tuberculosis

Central nervous system tuberculosis (CNS TB) has a high mortality and morbidity associated with severe inflammation. The blood-brain barrier (BBB) protects the brain from inflammation but the mechanisms causing BBB damage in CNS TB are uncharacterized. We demonstrate that Mycobacterium tuberculosis (Mtb) causes breakdown of type IV collagen and decreases tight junction protein (TJP) expression in a co-culture model of the BBB. This increases permeability, surface expression of endothelial adhesion molecules and leukocyte transmigration. TJP breakdown was driven by Mtb-dependent secretion of matrix metalloproteinase (MMP)-9. TJP expression is regulated by Sonic hedgehog (Shh) through transcription factor Gli-1. In our model, the hedgehog pathway was downregulated by Mtb-stimulation, but Shh levels in astrocytes were unchanged. However, Scube2, a glycoprotein regulating astrocyte Shh release was decreased, inhibiting Shh delivery to brain endothelial cells. Activation of the hedgehog pathway by addition of a Smoothened agonist or by addition of exogenous Shh, or neutralizing MMP-9 activity, decreased permeability and increased TJP expression in the Mtb-stimulated BBB co-cultures. In summary, the BBB is disrupted by downregulation of the Shh pathway and breakdown of TJPs, secondary to increased MMP-9 activity which suggests that these pathways are potential novel targets for host directed therapy in CNS TB.

Non-pathogenic tissue-resident CD8+ T cells uniquely accumulate in the brains of lupus-prone mice

Severe lupus often includes psychiatric and neurological sequelae, although the cellular contributors to CNS disease remain poorly defined. Using intravascular staining to discriminate tissue-localized from blood-borne cells, we find substantial accumulation of CD8⁺ T cells relative to other lymphocytes in brain tissue, which correlates with lupus disease and limited neuropathology. This is in contrast to all other affected organs, where infiltrating CD4⁺ cells are predominant. Brain-infiltrating CD8⁺ T cells represent an activated subset of those found in the periphery, having a resident-memory phenotype (CD69⁺CD122⁻PD1⁺CD44⁺CD62L⁻) and expressing adhesion molecules (VLA-4⁺LFA-1⁺) complementary to activated brain endothelium. Remarkably, infiltrating CD8⁺ T cells do not cause tissue damage in lupus-prone mice, as genetic ablation of these cells via β2 m deficiency does not reverse neuropathology, but exacerbates disease both in the brain and globally despite decreased serum IgG levels. Thus, lupus-associated inflammation disrupts the blood-brain barrier in a discriminating way biased in favor of non-pathogenic CD8⁺ T cells relative to other infiltrating leukocytes, perhaps preventing further tissue damage in such a sensitive organ.

Current Evidence for a Role of the Kynurenine Pathway of Tryptophan Metabolism in Multiple Sclerosis

The kynurenine pathway (KP) is the major metabolic pathway of the essential amino acid tryptophan (TRP). Stimulation by inflammatory molecules, such as interferon-γ (IFN-γ), is the trigger for induction of the KP, driving a complex cascade of production of both neuroprotective and neurotoxic metabolites, and in turn, regulation of the immune response and responses of brain cells to the KP metabolites. Consequently, substantial evidence has accumulated over the past couple of decades that dysregulation of the KP and the production of neurotoxic metabolites are associated with many neuroinflammatory and neurodegenerative diseases, including Parkinson’s disease, AIDS-related dementia, motor neurone disease, schizophrenia, Huntington’s disease, and brain cancers. In the past decade, evidence of the link between the KP and multiple sclerosis (MS) has rapidly grown and has implicated the KP in MS pathogenesis. KP enzymes, indoleamine 2,3-dioxygenase (IDO-1) and tryptophan dioxygenase (highest expression in hepatic cells), are the principal enzymes triggering activation of the KP to produce kynurenine from TRP. This is in preference to other routes such as serotonin and melatonin production. In neurological disease, degradation of the blood–brain barrier, even if transient, allows the entry of blood monocytes into the brain parenchyma. Similar to microglia and macrophages, these cells are highly responsive to IFN-γ, which upregulates the expression of enzymes, including IDO-1, producing neurotoxic KP metabolites such as quinolinic acid. These metabolites circulate systemically or are released locally in the brain and can contribute to the excitotoxic death of oligodendrocytes and neurons in neurological disease principally by virtue of their agonist activity at N-methyl-d-aspartic acid receptors. The latest evidence is presented and discussed. The enzymes that control the checkpoints in the KP represent an attractive therapeutic target, and consequently several KP inhibitors are currently in clinical trials for other neurological diseases, and hence may make suitable candidates for MS patients. Underpinning these drug discovery endeavors, in recent years, several advances have been made in how KP metabolites are assayed in various biological fluids, and tremendous advancements have been made in how specimens are imaged to determine disease progression and involvement of various cell types and molecules in MS.

Imaging of Leukocyte Trafficking in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder and is characterized by a progressive decline of cognitive functions. The neuropathological features of AD include amyloid beta (Aβ) deposition, intracellular neurofibrillary tangles derived from the cytoskeletal hyperphosphorylated tau protein, amyloid angiopathy, the loss of synapses, and neuronal degeneration. In the last decade, inflammation has emerged as a key feature of AD, but most studies have focused on the role of microglia-driven neuroinflammation mechanisms. A dysfunctional blood-brain barrier has also been implicated in the pathogenesis of AD, and several studies have demonstrated that the vascular deposition of Aβ induces the expression of adhesion molecules and alters the expression of tight junction proteins, potentially facilitating the transmigration of circulating leukocytes. Two-photon laser scanning microscopy (TPLSM) has become an indispensable tool to dissect the molecular mechanisms controlling leukocyte trafficking in the central nervous system (CNS). Recent TPLSM studies have shown that vascular deposition of Aβ in the CNS promotes intraluminal neutrophil adhesion and crawling on the brain endothelium and also that neutrophils extravasate in the parenchyma preferentially in areas with Aβ deposits. These studies have also highlighted a role for LFA-1 integrin in neutrophil accumulation in the CNS of AD-like disease models, revealing that LFA-1 inhibition reduces the corresponding cognitive deficit and AD neuropathology. In this article, we consider how current imaging techniques can help to unravel new inflammation mechanisms in the pathogenesis of AD and identify novel therapeutic strategies to treat the disease by interfering with leukocyte trafficking mechanisms.

Glycomaterials for immunomodulation, immunotherapy, and infection prophylaxis

Synthetic carbohydrate-modified materials that can engage the innate and adaptive immune systems are receiving increasing interest to confer protection against onset of future disease, such as pathogen infection, as well as to treat established diseases, such as autoimmunity and cancer.

Glial influences on BBB functions and molecular players in immune cell trafficking

The blood-brain barrier (BBB) constitutes an elaborate structure formed by specialized capillary endothelial cells, which together with pericytes and perivascular glial cells regulates the exchanges between the central nervous system (CNS) and the periphery. Intricate interactions between the different cellular constituents of the BBB are crucial in establishing a functional BBB and maintaining the delicate homeostasis of the CNS microenvironment. In this review, we discuss the role of astrocytes and microglia in inducing and maintaining barrier properties under physiological conditions as well as their involvement during neuroinflammatory pathologies. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger.

Agent based modeling of the effects of potential treatments over the blood-brain barrier in multiple sclerosis

Multiple sclerosis is a disease of the central nervous system that involves the destruction of the insulating sheath of axons, causing severe disabilities. Since the etiology of the disease is not yet fully understood, the use of novel techniques that may help to understand the disease, to suggest potential therapies and to test the effects of candidate treatments is highly advisable. To this end we developed an agent based model that demonstrated its ability to reproduce the typical oscillatory behavior observed in the most common form of multiple sclerosis, relapsing-remitting multiple sclerosis. The model has then been used to test the potential beneficial effects of vitamin D over the disease. Many scientific studies underlined the importance of the blood-brain barrier and of the mechanisms that influence its permeability on the development of the disease. In the present paper we further extend our previously developed model with a mechanism that mimics the blood-brain barrier behavior. The goal of our work is to suggest the best strategies to follow for developing new potential treatments that intervene in the blood-brain barrier. Results suggest that the best treatments should potentially prevent the opening of the blood-brain barrier, as treatments that help in recovering the blood-brain barrier functionality could be less effective.

Transient but not permanent benefit of neuronal progenitor cell therapy after traumatic brain injury: potential causes and translational consequences

Background: Numerous studies have reported a beneficial impact of neural progenitor cell transplantation on functional outcome after traumatic brain injury (TBI) during short and medium follow-up periods. However, our knowledge regarding long-term functional effects is fragmentary while a direct comparison between local and systemic transplantation is missing so far.

Objectives: This study investigated the long-term (12 week) impact of human fetal neuronal progenitor cell (hNPC) transplantation 24 h after severe TBI in rats.

Methods: Cells were either transplanted stereotactically (1 × 10⁵) into the putamen or systemically (5 × 10⁵) via the tail vein. Control animals received intravenous transplantation of vehicle solution.

Results: An overall functional benefit was observed after systemic, but not local hNPC transplantation by area under the curve analysis (p < 0.01). Surprisingly, this effect vanished during later stages after TBI with all groups exhibiting comparable functional outcomes 84 days after TBI. Investigation of cell-mediated inflammatory processes revealed increasing microglial activation and macrophage presence during these stages, which was statistically significant after systemic cell administration (p < 0.05). Intracerebral hNPC transplantation slightly diminished astrogliosis in perilesional areas (p < 0.01), but did not translate into a permanent functional benefit. No significant effects on angiogenesis were observed among the groups.

Conclusion: Our results suggest the careful long-term assessment of cell therapies for TBI, as well as to identify potential long-term detrimental effects of such therapies before moving on to clinical trials. Moreover, immunosuppressive protocols, though widely used, should be rigorously assessed for their applicability in the respective setup.

Control of cell migration through mRNA localization and local translation

Cell migration plays an important role in many normal and pathological functions such as development, wound healing, immune defense, and tumor metastasis. Polarized migrating cells exhibit asymmetric distribution of many cytoskeletal proteins, which is believed to be critical for establishing and maintaining cell polarity and directional cell migration. To target these proteins to the site of function, cells use a variety of mechanisms such as protein transport and messenger RNA (mRNA) localization-mediated local protein synthesis. In contrast to the former which is intensively investigated and relatively well understood, the latter has been understudied and relatively poorly understood. However, recent advances in the study of mRNA localization and local translation have demonstrated that mRNA localization and local translation are specific and effective ways for protein localization and are crucial for embryo development, neuronal function, and many other cellular processes. There are excellent reviews on mRNA localization, transport, and translation during development and other cellular processes. This review will focus on mRNA localization-mediated local protein biogenesis and its impact on somatic cell migration.

Silencing of neurotropic flavivirus replication in the central nervous system by combining multiple microRNA target insertions in two distinct viral genome regions

In recent years, microRNA-targeting has become an effective strategy for selective control of tissue-tropism and pathogenesis of both DNA and RNA viruses. Here, using a neurotropic flavivirus as a model, we demonstrate that simultaneous miRNA targeting of the viral genome in the open reading frame and 3'-noncoding regions for brain-expressed miRNAs had an additive effect and produced a more potent attenuation of the virus compared to separate targeting of those regions. Multiple miRNA co-targeting of these two distantly located regions completely abolished the virus neurotropism as no viral replication was detected in the developing brain of neonatal mice. Furthermore, no viral antigens were detected in neurons, and neuronal integrity in the brain of mice was well preserved. This miRNA co-targeting approach can be adapted for other viruses in order to minimize their replication in a cell- or tissue-type specific manner, but most importantly, to prevent virus escape from miRNA-mediated silencing.

Leukocyte migration in the interstitial space of non-lymphoid organs

Leukocyte migration through interstitial tissues is essential for mounting a successful immune response. Interstitial motility is governed by a vast array of cell-intrinsic and cell-extrinsic factors that together ensure the proper positioning of immune cells in the context of specific microenvironments. Recent advances in imaging modalities, in particular intravital confocal and multi-photon microscopy, have helped to expand our understanding of the cellular and molecular mechanisms that underlie leukocyte navigation in the extravascular space. In this Review, we discuss the key factors that regulate leukocyte motility within three-dimensional environments, with a focus on neutrophils and T cells in non-lymphoid organs.

Immune-related conditions and subsequent risk of brain cancer in a cohort of 4.5 million male US veterans

Background:

Case–control studies have reported an inverse association between self-reported history of allergy and risk of glioma, but cohort data are limited. Our objectives were to evaluate the associations of major groups of medically diagnosed immune-related conditions (allergy/atopy, autoimmune disease, diabetes, infectious/inflammatory disease) and to explore associations with specific conditions in relation to subsequent diagnosis of brain cancer in a large cohort study.

Methods:

We used hospital discharge records for a cohort of 4.5 million male US veterans, of whom 4383 developed primary brain cancer. Rate ratios (RRs) and 95% confidence intervals (CIs) were calculated using time-dependent Poisson regression.

Results:

We found a significant trend of decreasing RRs for brain cancer with longer duration of allergy/atopy (P=0.02), but not for other conditions studied. Rate ratios of brain cancer for allergy/atopy and diabetes with duration of 10 or more years were 0.60 (95% CI: 0.43, 0.83) and 0.75 (95% CI: 0.62, 0.93), respectively. Several associations with specific conditions were found, but these did not withstand correction for multiple comparisons.

Conclusions:

This study lends some support to an inverse association between allergy/atopy and diabetes of long duration and brain cancer risk, but prospective studies with biological samples are needed to uncover the underlying biological mechanisms.

Surveillance of the tumor mutanome by T cells during progression from primary to recurrent ovarian cancer

PURPOSE

Cancers accumulate mutations over time, each of which brings the potential for recognition by the immune system. We evaluated T-cell recognition of the tumor mutanome in patients with ovarian cancer undergoing standard treatment.

EXPERIMENTAL DESIGN

Tumor-associated T cells from 3 patients with ovarian cancer were assessed by ELISPOT for recognition of nonsynonymous mutations identified by whole exome sequencing of autologous tumor. The relative levels of mutations and responding T cells were monitored in serial tumor samples collected at primary surgery and first and second recurrence.

RESULTS

The vast majority of mutations (78/79) were not recognized by tumor-associated T cells; however, a highly specific CD8(+) T-cell response to the mutation hydroxysteroid dehydrogenase-like protein 1 (HSDL1)(L25V) was detected in one patient. In the primary tumor, the HSDL1(L25V) mutation had low prevalence and expression, and a corresponding T-cell response was undetectable. At first recurrence, there was a striking increase in the abundance of the mutation and corresponding MHC class I epitope, and this was accompanied by the emergence of the HSDL1(L25V)-specific CD8(+) T-cell response. At second recurrence, the HSDL1(L25V) mutation and epitope continued to be expressed; however, the corresponding T-cell response was no longer detectable.

CONCLUSION

The immune system can respond to the evolving ovarian cancer genome. However, the T-cell response detected here was rare, was transient, and ultimately failed to prevent disease progression. These findings reveal the limitations of spontaneous tumor immunity in the setting of standard treatments and suggest a high degree of ignorance of tumor mutations that could potentially be reversed by immunotherapy.

Visualizing leukocyte trafficking in the living brain with 2-photon intravital microscopy

Intravital imaging of the superficial brain tissue in mice represents a powerful tool for the dissection of the cellular and molecular cues underlying inflammatory and infectious central nervous system (CNS) diseases. We present here a step-by-step protocol that will enable a non-specialist to set up a two-photon brain-imaging model. The protocol offers a two-part approach that is specifically optimized for imaging leukocytes but can be easily adapted to answer varied CNS-related biological questions. The protocol enables simultaneous visualization of fluorescently labeled immune cells, the pial microvasculature and extracellular structures such as collagen fibers at high spatial and temporal resolution. Intracranial structures are exposed through a cranial window, and physiologic conditions are maintained during extended imaging sessions via continuous superfusion of the brain surface with artificial cerebrospinal fluid (aCSF). Experiments typically require 1-2 h of preparation, which is followed by variable periods of immune cell tracking. Our methodology converges the experience of two laboratories over the past 10 years in diseased animal models such as cerebral ischemia, lupus, cerebral malaria, and toxoplasmosis. We exemplify the utility of this protocol by tracking leukocytes in transgenic mice in the pial vessels under steady-state conditions.

Myosin I: A new pip(3) effector in chemotaxis and phagocytosis

Phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P(3)) is a key signaling molecule in chemotaxis, a directed cell migration toward chemoattractants. PtdIns(3,4,5)P(3) is transiently generated by chemotactic stimulation and activates reorganization of the actin cytoskeleton at the leading edge of migrating cells. In a recent study, we demonstrated that PtdIns(3,4,5)P(3) directly binds to three members of the actin-based motor protein myosin I (myosin ID, IE and IF) in Dictyostelium discoideum and recruits these proteins to the plasma membrane of the leading edge. The PtdIns(3,4,5)P(3)-regulated membrane recruitment of myosin I induced chemoattractant-stimulated actin polymerization and was therefore required for chemotaxis. Similarly, human myosin IF was translocated to the plasma membrane through interactions with PtdIns(3,4,5)P(3) upon chemotactic stimulation in a neutrophil cell line. Interestingly, we also found that the three PtdIns(3,4,5)P(3)-binding myosin I proteins function in phagocytosis, which involves both PtdIns(3,4,5)P(3) signaling and actin cytoskeleton remodeling. Our findings provide an evolutionarily conserved mechanism by which class I myosin transmits PtdIns(3,4,5)P(3) signals to the actin cytoskeleton.

Role of C-C chemokine receptor type 7 and its ligands during neuroinflammation

For decades, chemokines and their receptors have received a great deal of attention for their multiple roles in controlling leukocyte functions during inflammation and immunity. The ability of chemokines to convey remarkably versatile but context-specific signals identifies them as powerful modulators of immune responses generated in response to diverse pathogenic or non-infectious insults. A number of recent studies have speculated that the C-C chemokine receptor type 7 (CCR7), plays important roles in immune-cell trafficking in various tissue compartments during inflammation and in immune surveillance. Using computational modeling and microfluidics-based approaches, recent studies have explored leukocyte migration behavior in response to CCR7 ligands in a complex chemokine environment existing with other coexisting chemokine fields. In this review, we summarize the current understanding of the effects of soluble versus immobilized ligands and of the downstream signaling pathways of CCR7 that control leukocyte motility, directionality, and speed. This review also integrates the current knowledge about the role of CCR7 in coordinating immune responses between secondary lymphoid organs and peripheral tissue microenvironments during primary or secondary antigen encounters. CCR7 seems to influence distinct immunological events during inflammatory responses in the central nervous system (CNS) including immune-cell entry and migration, and neuroglial interactions. The clinical and pathological outcome may vary depending on its contribution in the inflamed CNS microenvironment. Understanding these mechanisms has direct implications for therapeutic developments favoring more protective and efficient immune responses.

Modulation of tumor tolerance in primary central nervous system malignancies

Central nervous system tumors take advantage of the unique immunology of the CNS and develop exquisitely complex stromal networks that promote growth despite the presence of antigen-presenting cells and tumor-infiltrating lymphocytes. It is precisely this immunological paradox that is essential to the survival of the tumor. We review the evidence for functional CNS immune privilege and the impact it has on tumor tolerance. In this paper, we place an emphasis on the role of tumor-infiltrating myeloid cells in maintaining stromal and vascular quiescence, and we underscore the importance of indoleamine 2,3-dioxygenase activity as a myeloid-driven tumor tolerance mechanism. Much remains to be discovered regarding the tolerogenic mechanisms by which CNS tumors avoid immune clearance. Thus, it is an open question whether tumor tolerance in the brain is fundamentally different from that of peripheral sites of tumorigenesis or whether it simply stands as a particularly strong example of such tolerance.

Signaling mechanisms for chemotaxis

Cells recognize external chemical gradients and translate these environmental cues into amplified intracellular signaling that results in elongated cell shape, actin polymerization toward the leading edge, and movement along the gradient. Mechanisms underlying chemotaxis are conserved evolutionarily from Dictyostelium amoeba to mammalian neutrophils. Recent studies have uncovered several parallel intracellular signaling pathways that crosstalk in chemotaxing cells. Here, we review these signaling mechanisms in Dictyostelium discoideum.

How do immune cells overcome the blood-brain barrier in multiple sclerosis?

The presence of the blood-brain barrier (BBB) restricts the movement of soluble mediators and leukocytes from the periphery to the central nervous system (CNS). Leukocyte entry into the CNS is nonetheless an early event in multiple sclerosis (MS), an inflammatory disorder of the CNS. Whether BBB dysfunction precedes immune cell infiltration or is the consequence of perivascular leukocyte accumulation remains enigmatic, but leukocyte migration modifies BBB permeability. Immune cells of MS subjects express inflammatory cytokines, reactive oxygen species (ROS) and enzymes that can facilitate their migration to the CNS by influencing BBB function, either directly or indirectly. In this review, we describe how immune cells from the peripheral blood overcome the BBB and promote CNS inflammation in MS through BBB disruption.

Analysis of cellular migration using a two-chamber methodology

Directed cell migration is fundamental to both physiological and pathophysiological processes such as embryogenesis, wound healing, and cancer metastasis. A complex series of events are required for directional cell migration, which is initiated by a migration-promoting or chemotactic stimulus, resulting in cellular polarization and entry into a cyclical pattern of leading edge protrusion, adhesion, and retraction of the trailing edge allowing cell movement. Heat shock proteins such as Hsp27, Hsp90, alphaB-crystallin, as well as heat shock transcription factors, are important players in both physiological and pathophysiological cell migration. A variety of techniques are currently available to assess cell migration, and among the most commonly utilized are those that employ a two-chamber methodology, such as that developed by Stephen Boyden in the early 1960s. Herein, we describe the use of a multiwell microchemotaxis migration assay that has the advantages of being reusable, inexpensive, highly reproducible, and requiring only a small volume of reagents.

MHC class I and TCR avidity control the CD8 T cell response to IL-15/IL-15Rα complex

IL-15 operates via a unique mechanism termed transpresentation. In this system, IL-15 produced by one cell type is bound to IL-15Rα expressed by the same cell and is presented to apposing cells expressing the IL-15Rβ/γC complex. We have shown that administering soluble IL-15Rα complexed with IL-15 can greatly enhance IL-15 activity. We now show that the naive CD8 T cell response to exogenous IL-15/IL-15Rα complex is MHC class I dependent. In the absence of β2 microglobulin, naive CD8 T cells scarcely proliferated in response to IL-15/IL-15Rα complex, whereas memory cells proliferated, although to a lesser extent, compared with levels in control mice. The loss of β2m or FcRn slightly reduced the extended half-life of IL-15/IL-15Rα complex, whereas FcRn deficiency only partially reduced the naive CD8 T cell proliferative response to IL-15/IL-15Rα complex. In addition, we demonstrated a link between TCR avidity and the ability of a T cell to respond to IL-15/IL-15Rα complex. Thus, T cells expressing low-avidity TCR responded poorly to IL-15/IL-15Rα complex, which correlated with a poor homeostatic proliferative response to lymphopenia. The inclusion of cognate peptide along with complex resulted in enhanced proliferation, even when TCR avidity was low. IL-15/IL-15Rα complex treatment, along with peptide immunization, also enhanced activation and the migratory ability of responding T cells. These data suggest that IL-15/IL-15Rα complex has selective effects on Ag-activated CD8 T cells. Our findings have important implications for directing IL-15/IL-15Rα complex-based therapy to specific Ag targets and illustrate the possible adjuvant uses of IL-15/IL-15Rα complex.

Overview of cellular immunotherapy for patients with glioblastoma

High grade gliomas (HGG) including glioblastomas (GBM) are the most common and devastating primary brain tumours. Despite important progresses in GBM treatment that currently includes surgery combined to radio- and chemotherapy, GBM patients' prognosis remains very poor. Immunotherapy is one of the new promising therapeutic approaches that can specifically target tumour cells. Such an approach could also maintain long term antitumour responses without inducing neurologic defects. Since the past 25 years, adoptive and active immunotherapies using lymphokine-activated killer cells, cytotoxic T cells, tumour-infiltrating lymphocytes, autologous tumour cells, and dendritic cells have been tested in phase I/II clinical trials with HGG patients. This paper inventories these cellular immunotherapeutic strategies and discusses their efficacy, limits, and future perspectives for optimizing the treatment to achieve clinical benefits for GBM patients.

Exogenous fms-like tyrosine kinase 3 ligand overrides brain immune privilege and facilitates recognition of a neo-antigen without causing autoimmune neuropathology

Soluble antigens diffuse out of the brain and can thus stimulate a systemic immune response, whereas particulate antigens (from infectious agents or tumor cells) remain within brain tissue, thus failing to stimulate a systemic immune response. Immune privilege describes how the immune system responds to particulate antigens localized selectively within the brain parenchyma. We believe this immune privilege is caused by the absence of antigen presenting dendritic cells from the brain. We tested the prediction that expression of fms-like tyrosine kinase ligand 3 (Flt3L) in the brain will recruit dendritic cells and induce a systemic immune response against exogenous influenza hemagglutinin in BALB/c mice. Coexpression of Flt3L with HA in the brain parenchyma induced a robust systemic anti-HA immune response, and a small response against myelin basic protein and proteolipid protein epitopes. Depletion of CD4(+)CD25+ regulatory T cells (Tregs) enhanced both responses. To investigate the autoimmune impact of these immune responses, we characterized the neuropathological and behavioral consequences of intraparenchymal injections of Flt3L and HA in BALB/c and C57BL/6 mice. T cell infiltration in the forebrain was time and strain dependent, and increased in animals treated with Flt3L and depleted of Tregs; however, we failed to detect widespread defects in myelination throughout the forebrain or spinal cord. Results of behavioral tests were all normal. These results demonstrate that Flt3L overcomes the brain's immune privilege, and supports the clinical development of Flt3L as an adjuvant to stimulate clinically effective immune responses against brain neo-antigens, for example, those associated with brain tumors.

Cell-autonomous and environmental contributions to the interstitial migration of T cells

A key to understanding the functioning of the immune system is to define the mechanisms that facilitate directed lymphocyte migration to and within tissues. The recent development of improved imaging technologies, most prominently multi-photon microscopy, has enabled the dynamic visualization of immune cells in real-time directly within intact tissues. Intravital imaging approaches have revealed high spontaneous migratory activity of T cells in secondary lymphoid organs and inflamed tissues. Experimental evidence points towards both environmental and cell-intrinsic cues involved in the regulation of lymphocyte motility in the interstitial space. Based on these data, several conceptually distinct models have been proposed in order to explain the coordination of lymphocyte migration both at the single cell and population level. These range from “stochastic” models, where chance is the major driving force, to “deterministic” models, where the architecture of the microenvironment dictates the migratory trajectory of cells. In this review, we focus on recent advances in understanding naïve and effector T cell migration in vivo. In addition, we discuss some of the contradictory experimental findings in the context of theoretical models of migrating leukocytes.

Trafficking of immune cells in the central nervous system

The CNS is an immune-privileged environment, yet the local control of multiple pathogens is dependent on the ability of immune cells to access and operate within this site. However, inflammation of the distinct anatomical sites (i.e., meninges, cerebrospinal fluid, and parenchyma) associated with the CNS can also be deleterious. Therefore, control of lymphocyte entry and migration within the brain is vital to regulate protective and pathological responses. In this review, several recent advances are highlighted that provide new insights into the processes that regulate leukocyte access to, and movement within, the brain.

Risk of meningioma and common variation in genes related to innate immunity

BACKGROUND

The etiology of meningioma, the second most common type of adult brain tumor in the United States, is largely unknown. Prior studies indicate that history of immune-related conditions may affect the risk of meningioma.

METHODS

To identify genetic markers for meningioma in genes involved with innate immunity, we conducted an exploratory association study of 101 meningioma cases and 330 frequency-matched controls of European ancestry using subjects from a hospital-based study conducted by the National Cancer Institute. We genotyped 1,407 "tag" single nucleotide polymorphisms (SNP) in 148 genetic regions chosen on the basis of an r2>0.8 and minor allele frequency of >5% in Caucasians in HapMap1. Risk of meningioma was estimated by odds ratios and 95% confidence intervals.

RESULTS

Seventeen SNPs distributed across 12 genetic regions (NFKB1 (3), FCER1G (3), CCR6 (2), VCAM1, CD14, TNFRSF18, RAC2, XDH, C1D, TLR1/TLR10/TLR6, NOS1, and DEFA5) were associated with the risk of meningioma with P<0.01. Although individual SNP tests were not significant after controlling for multiple comparisons, gene region-based tests were statistically significant (P<0.05) for TNFRSF18, NFKB1, FCER1G, CD14, C1D, CCR6, and VCAM1.

CONCLUSIONS AND IMPACT

Our results indicate that common genetic polymorphisms in innate immunity genes may be associated with risk of meningioma. Given the small sample size, replication of these results in a larger study of meningioma is needed.

A confocal and electron microscopic comparison of interferon beta-induced changes in vesicular stomatitis virus infection of neuroblastoma and nonneuronal cells

Vesicular stomatitis virus (VSV) replication is highly sensitive to interferon (IFN)-induced antiviral responses. Pretreatment of sensitive cultured cells with IFNbeta results in a 10(4)-fold reduction in the release of infectious VSV particles. However, differences exist between the mechanisms of reduced infectious particle titers in cell lines of neuroblastoma and nonneuronal lineage. In L929-fibroblast-derived cells, using immunofluorescence confocal microscopy, infection under control conditions reveals the accumulation of VSV matrix, phosphoprotein (P), and nucleocapsid (N) proteins over time, with induced cellular morphological changes indicative of cytopathic effects (CPEs). Upon observing L929 cells that had been pretreated with IFNbeta, neither detectable VSV proteins nor CPEs were seen, consistent with type I IFN antiviral protection. When using the same techniques to observe VSV infections of NB41A3 cells, a neuroblastoma cell line, aside from similar viral progression in the untreated control cells, IFNbeta-treated cells illustrated a severely attenuated VSV infection. Attenuated VSV progression was observed through detection of VSV matrix, P, and N proteins in isolated cells during the first 8 h of infection. However, by 18-24 h postinfection all neuroblastomas had succumbed to the viral infection. Finally, upon closer inspection of IFNbeta-treated NB41A3 cells, no detectable changes in VSV protein localization were identified compared with untreated, virally infected neuroblastomas. Next, to extend our study to test our hypothesis that virion assembly is compromised within type I IFN-treated neuroblastoma cells, we employed electron microscopy to examine our experimental conditions at the ultrastructural level. Using VSV-specific antibodies in conjunction with immuno-gold reagents, we observed several similarities between the two cell lines, such as identification of viroplasmic regions containing VSV N and P proteins and signs of stress-induced CPEs of VSV-infected cells, which had either been mock-treated or pretreated with interferon-beta (IFNbeta). One difference we observed between nonneuronal and neuroblastoma cells was more numerous actively budding VSV virions across untreated L929 plasma membranes compared with untreated NB41A3 cells. Additionally, IFNbeta-treated, VSV-infected L929 cells exhibited neither cytoplasmic viroplasm nor viral protein expression. In contrast, IFNbeta-treated, VSV-infected NB41A3 cells showed evidence of VSV infection at a very low frequency as well as small-scale viroplasmic regions that colocalized with viral N and P proteins. Finally, we observed that VSV viral particles harvested from untreated VSV-infected L929 and NB41A3 cells were statistically similar in size and shape. A portion of VSV virions from IFNbeta-treated, virally infected NB41A3 cells were similar in size and shape to virus from both untreated cell types. However, among the sampling of virions, pleomorphic viral particles that were identified from IFNbeta-treated, VSV-infected NB41A3 cells were different enough to suggest a misassembly mechanism as part of the IFNbeta antiviral state in neuroblastoma cells.

Immunotherapy can reject intracranial tumor cells without damaging the brain despite sharing the target antigen

Although vaccines targeting tissue differentiation Ags represent a promising strategy for cancer immunotherapy, the risk of triggering autoimmune damage to normal tissues remains to be determined. Immunizing against a melanoma-associated Ag, dopachrome tautomerase (DCT), which normal melanocytes and glial cells also express, allowed concurrent analysis of autoimmune consequences in multiple tissues. We show that vaccination with recombinant adenovirus expressing DCT elicited a strong CTL response in C57BL/6 mice, leading to protection against intracranial challenge with B16-F10 melanoma cells. Both histological analysis and behavioral testing indicated that there was no evidence of neuropathology in vaccinated animals and long-term survivors. Although vitiligo or demyelination could be induced by additional stimuli (i.e., surgery or inflammation) in DCT-vaccinated mice, it did not extend beyond the inflammatory area, suggesting that there is self-regulatory negative feedback in normal tissues. These results demonstrate that it is possible to vaccinate against a tumor embedded in a vital organ that shares the target Ag.

Mechanisms maintaining peripheral tolerance

The presentation of self-peptide-MHC complexes in the periphery to potentially autoreactive T cells that have escaped negative selection in the thymus poses an important problem to the immune system. In this review, I discuss data that reveal barriers preventing peripheral T cell recognition of self-peptide-MHC complexes, as well as the physiological mechanisms that ensure the elimination or functional inactivation (anergy) of T cells that do come to recognize self-peptide-MHC and threaten the health of the individual.

Treatment of Parkinson's disease model mice with allogeneic embryonic stem cells: necessity of immunosuppressive treatment for sustained improvement

OBJECTIVE

The purpose of the present study was to examine the efficacy of transplantation of mouse embryonic stem (ES) into Parkinson's disease (PD) model mice as well as the necessity of immunosuppression in allogeneic donor-host combinations.

MATERIALS AND METHODS

ES cells, derived from SvJ129 strain mice, were differentiated into tyrosine hydroxylase (TH)-positive neurons in vitro by an embryoid body (EB)-based multistep differentiation method and used as graft cells for PD mice, which were prepared by injection of 6-hydroxydopamine (OHDA) into C57BL/6, BALB/c and C3H/HeN strains. Mice from each strain were divided into Groups 1-3. Four weeks after the 6-OHDA injection, Group 1 received phosphate-buffered saline in the striatum wounds, while Group 2 received 2 x 10(4) graft cells, and Group 3 mice received 2 x 10(4) graft cells and were also treated with cyclosporine A.

RESULTS

Apomorphine-induced rotational behavior was improved in Groups 2 and 3, but not in Group 1. However, the behavioral improvement ceased later in Group 2, whereas sustained improvement was observed in Group 3 throughout the 8 week observation period after transplantation. ES-derived TH(+) cells were found at the grafted sites at the end of the experiment in Groups 2 and 3, and tended to be more abundant in Group 3.

CONCLUSION

Intra-striatum transplantation of ES-derived dopaminergic neurons was effective in treating PD mice, even in allogeneic donor-host combinations. Immunosuppressive treatment did not have an effect on initial behavioral restoration after transplantation; however, it was necessary for sustained improvement over a prolonged period.

Liver architecture, cell function, and disease

The liver is an organ consisting of the largest reticulo-endothelial cell network in the body and playing an important role in host defense against invading microorganisms. The organ is comprised of parenchymal cells and many different types of non-parenchymal cells, all of which play a significant role. Even biliary epithelial cells are not only the target in autoimmune liver diseases but also have central role in orchestrating several immune cells involved in both innate and acquired immunity. Tissue damage caused by various agents results in inflammation, necrosis, fibrosis, and, eventually, distortion of normal hepatic architecture, cirrhosis, and functional deterioration.

Common variation in genes related to innate immunity and risk of adult glioma

Current evidence suggests that immune system alterations contribute to the etiology of adult glioma, the most common adult brain tumor. Although previous studies have focused on variation in candidate genes in the adaptive immune system, the innate immune system has emerged as a critical avenue for research given its known link with carcinogenesis. To identify genetic markers in pathways critical to innate immunity, we conducted an association study of 551 glioma cases and 865 matched controls of European ancestry to investigate "tag" single nucleotide polymorphisms (SNP) in 148 genetic regions. Two independent U.S. case-control studies included were as follows: a hospital-based study conducted by the National Cancer Institute (263 cases, 330 controls) and a community-based study conducted by the National Institute for Occupational Safety and Health (288 cases, 535 controls). Tag SNPs (1,397) chosen on the basis of an r(2) of >0.8 and minor allele frequency of >5% in Caucasians in HapMap1 were genotyped. Glioma risk was estimated by odds ratios. Nine SNPs distributed across eight genetic regions (ALOX5, IRAK3, ITGB2, NCF2, NFKB1, SELP, SOD1, and STAT1) were associated with risk of glioma with P value of <0.01. Although these associations were no longer statistically significant after controlling for multiple comparisons, the associations were notably consistent in both studies. Region-based tests were statistically significant (P < 0.05) for SELP, SOD, and ALOX5. Analyses restricted to glioblastoma (n = 254) yielded significant associations for the SELP, DEFB126/127, SERPINI1, and LY96 genetic regions. We have identified a promising set of innate immunity-related genetic regions for further investigation.

T cell regulatory plasmacytoid dendritic cells expressing indoleamine 2,3 dioxygenase

Mature dendritic cells (DCs) are potent stimulators of T cells that recognize antigens presented by the DCs. In this chapter we describe mature DCs that suppress T cell responses to antigens they present due to expression of the intracellular enzyme indoleamine 2,3 dioxygenase (IDO). IDO-competent DCs are a subset of plasmacytoid DCs that can be induced to express IDO under certain inflammatory conditions in humans and mice. Though rare, IDO-expressing DCs acquire potent T cell suppressor activity that may predominate over the T cell stimulatory functions of all other antigen-presenting cells in physiologic environments due in part, to cooperation with regulatory T cells. Thus, IDO-expressing DCs are critical regulators of adaptive immunity that contribute to a wide range of inflammatory disease processes. As such, manipulating IDO expression in DCs using IDO inhibitors or IDO inducers offers considerable opportunities to improve immunotherapies in a range of clinically-significant disease syndromes.

CD44 mediates successful interstitial navigation by killer T cells and enables efficient antitumor immunity

Although T lymphocytes are constitutively nonadherent cells, they undergo facultative polarity during migration and upon interaction with cells presenting cognate antigen, suggesting that cell polarity might be critical for target cell destruction. Using two-photon imaging of tumor-infiltrating T lymphocytes, we found that CD44, a receptor for extracellular matrix proteins and glycosaminoglycans, was crucial for interstitial T cell navigation and, consequently, efficient tumor cell screening. CD44 functioned as a critical regulator of intratumoral movement by stabilizing cell polarity in migrating T cells, but not during target cell interactions. Stable anterior-posterior asymmetry was maintained by CD44 independently of its extracellular domain. Instead, migratory polarity depended on the recruitment of ezrin, radixin, moesin (ERM) proteins by the intracellular domain of CD44 to the posterior cellular protrusion. Our results formally demonstrate that CD44-dependent T lymphocyte locomotion within target sites represents an essential immunologic checkpoint that determines the potency of T cell effector functions.

Behavior of parasite-specific effector CD8+ T cells in the brain and visualization of a kinesis-associated system of reticular fibers

To understand lymphocyte behavior in the brain, we used two-photon microscopy to visualize effector CD8(+) T cells during toxoplasmic encephalitis. These cells displayed multiple behaviors with two distinct populations of cells apparent: one with a constrained pattern of migration and one with a highly migratory subset. The proportion of these populations varied over time associated with changes in antigen availability as well as T cell expression of the inhibitory receptor PD1. Unexpectedly, the movement of infiltrating cells was closely associated with an infection-induced reticular system of fibers. This observation suggests that, whereas in other tissues pre-existing scaffolds exist that guide lymphocyte migration, in the brain specialized structures are induced by inflammation that guide migration of T cells in this immune-privileged environment.