[Show abstract][Hide abstract] ABSTRACT: Astrocytes have complex roles in health and disease, thus it is important to study the pathways that regulate their function. Here we report that lactosylceramide (LacCer) synthesized by β-1,4-galactosyltransferase 6 (B4GALT6) is upregulated in the central nervous system (CNS) of mice during chronic experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). LacCer acts in an autocrine manner to control astrocyte transcriptional programs that promote neurodegeneration. In addition, LacCer in astrocytes controls the recruitment and activation of microglia and CNS-infiltrating monocytes in a non-cell autonomous manner by regulating production of the chemokine CCL2 and granulocyte-macrophage colony-stimulating factor (GM-CSF), respectively. We also detected high B4GALT6 gene expression and LacCer concentrations in CNS MS lesions. Inhibition of LacCer synthesis in mice suppressed local CNS innate immunity and neurodegeneration in EAE and interfered with the activation of human astrocytes in vitro. Thus, B4GALT6 regulates astrocyte activation and is a potential therapeutic target for MS and other neuroinflammatory disorders.
[Show abstract][Hide abstract] ABSTRACT: Objectives
Dendritic cells (DCs) serve a critical role both in promoting and inhibiting adaptive immunity. The goal of this study was to investigate the effect of natalizumab (NTZ) treatment on DC numbers, phenotype, and function in patients with multiple sclerosis (MS).
Frequency and phenotype of myeloid and plasmacytoid DCs (MDCs and PDCs, respectively) were analyzed in blood from two separate cohorts of untreated, interferon-treated, or NTZ-treated MS patients. In addition, PDCs were stimulated with CpG-containing oligonucleotides or co-cultured with homologous T cells in the presence or absence of NTZ in vitro to determine functional effects of NTZ treatment.
We observed that NTZ treatment was associated with a 25–50% reduction in PDC frequency in peripheral blood as compared to untreated MS patients, while the frequency of MDCs was unchanged. PDCs in NTZ-treated patients displayed a mature, activated phenotype with increased expression of HLA-DR, TLR9, CCR7, IL-6 and IL-12. In contrast, in vitro treatment with NTZ did not increase markers of PDC activation or their ability to induce T cell differentiation.
Our study shows that NTZ treatment is associated with a reduced frequency of PDCs in the peripheral circulation, but that PDCs in NTZ-treated individuals display an activated phenotype. Taken together the data suggests that transmigration of activated PDCs is preferentially affected by blockade of integrin α4 leading to an increased frequency of activated PDCs in blood.
[Show abstract][Hide abstract] ABSTRACT: Osteopontin (OPN) is a pleiotropic protein with important roles in inflammation and immunity that has been suggested as a candidate biomarker for disease activity in multiple sclerosis (MS).
We evaluated plasma levels of OPN in an unselected cohort of MS patients, to determine its potential as a biomarker for disease subtype and/or disease activity in a regular clinical setting.
We analyzed OPN plasma levels in 492 consecutive MS patients, using a commercial enzyme-linked immunosorbent assay (ELISA).
OPN levels were higher in relapsing-remitting and secondary progressive MS, compared to healthy controls. Treatment with natalizumab or glatiramer acetate was associated with lower OPN levels. There was no significant association between the OPN levels and disease activity, as measured by clinical or radiological criteria. One-third of patients with high OPN levels had concurrent disorders that may also be associated with increased OPN expression, and which may mask a modest effect of MS disease activity on OPN levels.
Our data do not support a role for circulating OPN levels as a biomarker for disease activity in a heterogeneous clinical setting, but does not rule out a potential role in the cerebrospinal fluid, in a controlled setting such as a clinical trial, or in concert with other biomarkers.
No preview · Article · Sep 2013 · Multiple Sclerosis
[Show abstract][Hide abstract] ABSTRACT: Studies of the underlying immune mechanisms of multiple sclerosis (MS) in children may shed light on the initial events of MS pathogenesis. We studied T cell responses to myelin peptides in 10 pediatric MS patients (PMS), 10 pediatric healthy controls (PHC), 10 adult MS patients (AMS) and 10 adult healthy controls (AHC). A significantly higher proportion of divided CD4+ T cell responses in response to myelin peptides by the CFSE assay in PMS compared to PHC at both concentrations of myelin peptide tested (t test, 95% CI, p=0.0067 for MP1; p=0.0086 for MP10), and between PMS and AMS (p=0.0012 at 1μg/mL of myelin peptides, p<0.0001 at 10μg/mL) was found. In addition, T cells with a central memory phenotype producing IL-17 were increased in PMS compared to PHC (p<0.05). IL-7 levels in culture supernatants were elevated in PMS compared to PHC and AMS (t test<0.01).
Full-text · Article · Dec 2012 · Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: The subventricular zone (SVZ) of the brain constitutes a niche for neural stem and progenitor cells that can initiate repair after central nervous system (CNS) injury. In a relapsing-remitting model of experimental autoimmune encephalomyelitis (EAE), the neural stem cells (NSCs) become activated and initiate regeneration during acute disease, but lose this ability during the chronic phases of disease. We hypothesized that chronic microglia activation contributes to the failure of the NSC repair potential in the SVZ.
Using bromodeoxyuridine injections at different time points during EAE, we quantified the number of proliferating and differentiating progenitors, and evaluated the structure of the SVZ by electron microscopy. In vivo minocycline treatment during EAE was used to address the effect of microglia inactivation on SVZ dysfunction.
In vivo treatment with minocycline, an inhibitor of microglia activation, increases stem cell proliferation in both naive and EAE animals. Minocycline treatment decreases cortical and periventricular pathology in the chronic phase of EAE, improving the proliferation of Sox2 stem cells and NG2 oligodendrocyte precursors cells originating in the SVZ and their differentiation into mature oligodendrocytes.
These data suggest that failure of repair observed during chronic EAE correlates with microglia activation and that treatments targeting chronic microglial activation have the potential for enhancing repair in the CNS.
Full-text · Article · May 2011 · Annals of Neurology
[Show abstract][Hide abstract] ABSTRACT: Evidence has been presented for the involvement of immune mechanisms in the pathogenesis of myasthenia gravis (MG) and multiple sclerosis (MS). The production of autoantibodies in both diseases is regulated by T-cells by means of cytokines. Interleukin-13 (IL-13) is mainly produced by T-helper type 2 cells and induces B-cell proliferation and antibody class switch. The role of IL-13 in MG and MS is not known. We employed in situ hybridization with synthetic radiolabelled oligonucleotide probes to detect and enumerate blood and cerebrospinal fluid (CSF) mononuclear cells (MNC) expressing IL-13 mRNA from patients with MG, MS, optic neuritis (ON), other inflammatory neurological diseases (OIND) and healthy controls. MG is associated with elevated levels of acetylcholine receptor (AChR) reactive IL-13 mRNA expressing blood MNC compared to control patients. In MS, numbers of MBP-reactive IL-13 mRNA expressing MNC were higher compared to cultures without antigen stimulation. The levels of MBP-reactive IL-13 mRNA positive MNC were higher in MS compared to MG, but not other controls. There were no differences in spontaneous IL-13 mRNA expressing blood MNC numbers between MG, MS, ON and control patients. The data suggest the involvement of IL-13 in both MG and MS.
No preview · Article · Jan 2011 · European Journal of Neurology
[Show abstract][Hide abstract] ABSTRACT: Beta-interferon (IFN-β) is a promising treatment in multiple sclerosis (MS), reducing the exacerbation rate and MRI lesion burden, as well as the disease progression in relapsing-remitting MS. IFN-β was originally defined by its antiviral effects, but the interest has recently been focused on its immunomodulatory properties. Myelin basic protein (MBP) is one of several autoantigens considered to be the target for autoaggressive immune responses, which eventually might lead to the development of MS. To study in-vitro effects of IFN-β1b on MBP induced cytokine expression, mRNA for the Th1 cytokines IFN-γ and TNF-α, the Th2 related IL-4 and IL-6, the cytolytic perforin and the immune response downregulating TGF-β was measured with in situ hybridization after culture of blood mononuclear cells (MNC) in the presence and absence of MBP. Numbers of cells expressing IFN-γ, TNF-α, perforin and IL-4 mRNA were significantly suppressed after culture with 10 U/ml IFN-β1b. No such effect was seen on MBP induced IL-6 or TGF-β mRNA expression. These observations suggest that one of the major effects of IFN-β1b is the induction of a shift in the cytokine mRNA profile towards a more immunosuppressive pattern. In parallel in vitro tests, the control substance dexametasone (40 μg/ml) reduced the numbers of cells expressing mRNA for all cytokines under study with the exception of TGF-β, to an extent equal to or even more pronounced than IFN-β1b.
No preview · Article · Jan 2011 · European Journal of Neurology
[Show abstract][Hide abstract] ABSTRACT: Interleukin 12 (IL-12), a cytokine that promotes generation of helper T cells subtype 1, is increased in multiple sclerosis. Albuterol sulfate, a β2-adrenergic agonist, reduces IL-12 expression, so we tested the effect of albuterol as an add-on treatment to glatiramer acetate therapy.
To investigate the clinical and immunologic effects of albuterol treatment as an add-on therapy in patients starting glatiramer acetate treatment.
Single-center double-masked clinical trial.
Academic research. Patients Subjects with relapsing-remitting multiple sclerosis.
In this single-center double-masked clinical trial, subjects with relapsing-remitting multiple sclerosis were randomized to receive a subcutaneous injection of glatiramer acetate (20 mg) plus an oral dose of placebo daily for 2 years or a subcutaneous injection of glatiramer acetate (20 mg) plus an oral dose of albuterol daily for 2 years. The primary clinical efficacy measurement was the change in Multiple Sclerosis Functional Composite at 2 years, and the primary immunologic end point was the change in expression of IL-13 and interferon γ at each study time point. The classification level of evidence from this trial is C for each question, as this is the first class II clinical trial addressing the efficacy of glatiramer acetate plus albuterol.
Forty-four subjects were randomized to receive glatiramer acetate plus albuterol or glatiramer acetate plus placebo, and 39 subjects contributed to the analysis. Improvement in the Multiple Sclerosis Functional Composite was observed in the glatiramer acetate plus albuterol group at the 6-month (P = .005) and 12-month (P = .04) time points but not at the 24-month time point. A delay in the time to first relapse was also observed in the glatiramer acetate plus albuterol group (P = .03). Immunologically, IL-13 and interferon-γ production decreased in both treatment groups, and a treatment effect on IL-13 production was observed at the 12-month time point (P < .05). Adverse events were generally mild, and only 3 moderate or severe events were considered related to the treatment.
Treatment with glatiramer acetate plus albuterol is well tolerated and improves clinical outcomes in patients with multiple sclerosis.
clinicaltrials.gov Identifier: NCT00039988.
Full-text · Article · Sep 2010 · Archives of neurology
[Show abstract][Hide abstract] ABSTRACT: Natalizumab is an antibody directed against integrin alpha4 that reduces disease activity in patients with multiple sclerosis (MS) by blocking migration of T and B cells into the CNS. The goal of this study was to characterize the effects of natalizumab treatment on cytokine production and expression of activation markers, costimulatory molecules, and trafficking determinants on CD4+ and CD8+ T cells.
In a longitudinal study, we investigated the expression of surface makers and cytokine expression on peripheral blood lymphocytes from 28 patients with MS who started natalizumab treatment and were followed for 1 year. A mixed effects model was used to compare pretreatment to on-treatment measurements.
The frequency of CD4+ T cells producing interferon-gamma, tumor necrosis factor, and interleukin (IL)-17 upon anti-CD3 stimulation increased 6 months after initiation of natalizumab treatment and remained elevated throughout the follow-up. The frequency of CD4+ T cells expressing CD25, HLA-DR, and CCR6 ex vivo was increased at one or more time points during treatment. Among CD8+ T cells, the frequency of cells producing IL-2 and IL-17 after stimulation was increased during natalizumab treatment, as was the frequency of CD8+ T cells expressing CD58 and CCR5 ex vivo. The increase in the frequency of activated cells could not be replicated by in vitro exposure to natalizumab.
Natalizumab treatment increases the percentage of activated leukocytes producing proinflammatory cytokines in blood, presumably due to sequestration of activated cells in the peripheral circulation.
[Show abstract][Hide abstract] ABSTRACT: The onset of neurological signs in experimental autoimmune encephalomyelitis is tightly associated with infiltration and reactivation of T cells in the central nervous system. The anatomic localization of the initial T cell-antigen-presenting cell (APC) interactions leading to reactivation of T cells in the central nervous system is, however, still unclear. We hypothesized that activated CD4(+) T cells gain direct access to the subarachnoid space and become reactivated on encounter with cognate antigen in this compartment.
C57Bl/6 mice were immunized with MOG35-55, and interactions between CD4(+) T cells and major histocompatibility class II+ APCs in the subarachnoid space were investigated using flow cytometry, confocal microscopy of leptomeningeal whole-mount preparations, time-lapse microscopy of leptomeningeal explants, and in vitro proliferation assays.
CD4(+) T cells, polarized to produce Th1/Th17 cytokines, accumulated in the subarachnoid space early during the course of experimental autoimmune encephalomyelitis, before CD4(+) T cells were detected in the spinal cord parenchyma. At this time point, leptomeningeal but not parenchymal CD4(+) T cells incorporated bromodeoxyuridine, indicating local proliferation of CD4(+) T cells in the subarachnoid space. Time-lapse microscopy indicated that these CD4(+) T cells actively scanned the tissue and interacted with local major histocompatibility class II+ APCs, resulting in long-lasting interactions between CD4(+) T cells and major histocompatibility class II+ APCs, suggestive of immunological synapses.
These results support the concept that immune surveillance of the central nervous system involves the subarachnoid space and indicate that the leptomeninges play an important role in experimental autoimmune encephalomyelitis initiation.
Full-text · Article · Apr 2009 · Annals of Neurology
[Show abstract][Hide abstract] ABSTRACT: The persistence of human autoimmune diseases is thought to be mediated predominantly by memory T cells. We investigated the phenotype and migration of memory versus effector T cells in vivo in experimental autoimmune encephalomyelitis (EAE). We found that memory CD4(+) T cells up-regulated the activation marker CD44 as well as CXCR3 and ICOS, proliferated more and produced more interferon-gamma and less interleukin-17 compared to effector T cells. Moreover, adoptive transfer of memory T cells into T cell receptor (TCR)alphabeta(-/-) recipients induced more severe disease than did effector CD4(+) T cells with marked central nervous system inflammation and axonal damage. The uniqueness of disease mediated by memory T cells was confirmed by the differential susceptibility to immunomodulatory therapies in vivo. CD28-B7 T cell costimulatory signal blockade by CTLA4Ig suppressed effector cell-mediated EAE but had minimal effects on disease induced by memory cells. In contrast, ICOS-B7h blockade exacerbated effector T cell-induced EAE but protected from disease induced by memory T cells. However, blockade of the OX40 (CD134) costimulatory pathway ameliorated disease mediated by both memory and effector T cells. Our data extend the understanding of the pathogenicity of autoreactive memory T cells and have important implications for the development of novel therapies for human autoimmune diseases.
Full-text · Article · Jul 2008 · American Journal Of Pathology
[Show abstract][Hide abstract] ABSTRACT: Notch signaling plays an important role during T cell development in the thymus and in T cell activation but the role of Notch in autoimmunity is not clear. We investigated the role of Jagged1 and Delta1 in experimental autoimmune encephalomyelitis. During experimental autoimmune encephalomyelitis, Delta1 expression is up-regulated on dendritic cells and B cells after priming while Jagged1 is up-regulated only on dendritic cells. Administration of anti-Jagged1 Ab exacerbated clinical disease while that of anti-Delta1 Ab reduced the severity of the clinical disease. In contrast, administration of Jagged1-Fc protected from disease, that of Delta1-Fc exacerbated disease. Treatment with Jagged1-Fc was associated with increased IL-10-producing Ag-specific cells in the CNS, while anti-Jagged1 decreased the frequency of IL-10-producing cells. Treatment with Delta1-Fc increased Th1 cells in the CNS, while anti-Delta-1 decreased the frequency of Th1 cells. Manipulation of Delta1 or Jagged1 had no effect on the frequency of Th17 cells or FoxP3(+) cells. Moreover, Jagged1 may play a role in CNS homeostasis because murine astrocytes specifically express Jagged1 that is up-regulated by TGF-beta, whereas IFN-gamma, TNF-alpha, and IL-17 decrease Jagged1 expression. Our study provides novel data about differential roles of Notch ligands in regulating inflammation in the periphery as well as in the CNS.
Full-text · Article · Dec 2007 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Cortical pathology, callosal atrophy and axonal loss are substrates of progression in multiple sclerosis (MS). Here we describe cortical, periventricular subcortical lesions and callosal demyelination in relapsing-remitting experimental autoimmune encephalomyelitis in SJL mice that are similar to lesions found in MS. Unlike the T-cell infiltrates that peak during acute disease, we found that microglia activation persists through the chronic disease phase. Microglia activation correlated with abnormal phosphorylation of neurofilaments in the cortex and stripping of synaptic proteins in cortical callosal projecting neurons. There was significant impairment of retrograde labeling of NeuN-positive callosal projecting neurons and reduction in the labelling of their transcallosal axons. These data demonstrate a novel paradigm of cortical and callosal neuropathology in a mouse model of MS, perpetuated by innate immunity. These features closely mimic the periventricular and cortical pathology described in MS patients and establish a model that could be useful to study mechanisms of progression in MS.
[Show abstract][Hide abstract] ABSTRACT: Circulating memory T cells can be divided into tissue-specific subsets, which traffic through distinct tissue compartments during physiologic immune surveillance, based on their expression of adhesion molecules and chemokine receptors. We reasoned that a bias (either enrichment or depletion) of CSF T cell expression of known organ-specific trafficking determinants might suggest that homing of T cells to the subarachnoid space could be governed by a CNS-specific adhesion molecule or chemokine receptor.
The expression of cutaneous leukocyte antigen (CLA) and CC-chemokine receptor 4 (CCR4; associated with skin-homing) as well as the expression of integrin alpha4beta7 and CCR9 (associated with gut-homing) was analyzed on CD4+ memory T cells in CSF from individuals with non-inflammatory neurological diseases using flow cytometry. CSF contained similar proportions of CD4+ memory T cells expressing CLA, CCR4, integrin alpha4beta7 and CCR9 as paired blood samples.
The results extend our previous findings that antigen-experienced CD4+ memory T cells traffic through the CSF in proportion to their abundance in the peripheral circulation. Furthermore, the ready access of skin- and gut-homing CD4+ memory T cells to the CNS compartment via CSF has implications for the mechanisms of action of immunotherapeutic strategies, such as oral tolerance or therapeutic immunization, where immunogens are administered using an oral or subcutaneous route.
[Show abstract][Hide abstract] ABSTRACT: Leukocyte infiltrates characterize tissue inflammation and are thought to be integral in the pathogenesis of multiple sclerosis (MS). This attribute underlines the importance of understanding mechanisms of leukocyte migration. Chemokines are secreted proteins which govern leukocyte trafficking into targeted organs. Chemokine receptors (CKR) are differentially expressed on leukocytes and their modulation is a potential target for MS disease modifying therapies. Chemokines and their receptors are also potential biomarkers of both disease activity and response to treatment. We describe the fluctuations in CKR expression on peripheral leukocytes in a group of MS patients followed longitudinally for up to 36 months. We observed little fluctuation in CKR expression within each patient over time, despite considerable variability in CKR expression between patients. These observations suggest that individual patients have a CKR set point, and this set point varies from one patient to another. Evaluation of chemokines or chemokine receptors as biomarkers in MS will need to account for this individual variability in CKR expression.
[Show abstract][Hide abstract] ABSTRACT: Understanding the mechanisms of immune cell migration to multiple sclerosis lesions offers significant therapeutic potential. This study focused on the chemokines CXCL12 (SDF-1) and CXCL13 (BCA-1), both of which regulate B cell migration in lymphoid tissues. We report that immunohistologically CXCL12 was constitutively expressed in CNS parenchyma on blood vessel walls. In both active and chronic inactive multiple sclerosis lesions CXCL12 protein was elevated and detected on astrocytes and blood vessels. Quantitative PCR demonstrated that CXCL13 was produced in actively demyelinating multiple sclerosis lesions, but not in chronic inactive lesions or in the CNS of subjects who had no neurological disease. CXCL13 protein was localized in perivascular infiltrates and scattered infiltrating cells in lesion parenchyma. In the CSF of relapsing-remitting multiple sclerosis patients, both CXCL12 and CXCL13 were elevated. CXCL13, but not CXCL12, levels correlated strongly with intrathecal immunoglobulin production as well as the presence of B cells, plasma blasts and T cells. About 20% of CSF CD4+ cells and almost all B cells expressed the CXCL13 receptor CXCR5. In vitro, CXCL13 was produced by monocytes and at much higher levels by macrophages. CXCL13 mRNA and protein expression was induced by TNFalpha and IL-1beta but inhibited by IL-4 and IFNgamma. Together, CXCL12 and CXCL13 are elevated in active multiple sclerosis lesions and CXCL12 also in inactive lesions. The consequences of CXCL12 up-regulation could be manifold. CXCL12 localization on blood vessels indicates a possible role in leucocyte extravasation, and CXCL12 may contribute to plasma cell persistence since its receptor CXCR4 is retained during plasma cell differentiation. CXCL12 may contribute to axonal damage as it can become a neurotoxic mediator of cleavage by metalloproteases, which are present in multiple sclerosis lesions. The strong linkage of CXCL13 to immune cells and immunoglobulin levels in CSF suggests that this is one of the factors that attract and maintain B and T cells in inflamed CNS lesions. Therefore, both CXCL13 and CXCR5 may be promising therapeutic targets in multiple sclerosis.
[Show abstract][Hide abstract] ABSTRACT: Chemokines and chemokine receptors play a key role in the transmigration of leucocytes across the blood-brain barrier (BBB). CCR2 is the major receptor for CCL2, a potent monocyte and T cell chemoattractant. CCR2 and CCL2 have been consistently associated with a pathogenic role in experimental autoimmune encephalomyelitis, using knockout and transgenic mice, neutralizing antibodies, peptide antagonists and DNA vaccination. However, the significance of CCL2 and CCR2 in multiple sclerosis is enigmatic, because CCL2 levels are consistently decreased in the CSF of patients with this disease and other chronic neuroinflammatory conditions, despite abundant expression within lesional multiple sclerosis tissues. This study used an in vitro BBB model to test the hypothesis that CCL2 is removed from the extracellular fluid by CCR2-positive migrating cells as they cross the BBB, resulting in decreased CSF CCL2 levels. We showed that CCR2-positive T cells and monocytes migrated selectively across the in vitro BBB, and that CCL2 on the abluminal (tissue) side was consumed by migrating T cells and monocytes. Next, we used a new anti-CCR2 antibody to show that CCR2-positive mononuclear inflammatory cells could be readily detected in appropriate positive control tissues, but that CCR2+ cells were very infrequently found in multiple sclerosis lesions. We then showed that CCR2 receptor density on T cells and monocytes was specifically downregulated upon in vitro BBB transmigration in response to CCL2, but not irrelevant chemokines. These findings document a novel strategy for analysing chemokine receptor function in inflammatory CNS disease, and support the hypothesis that CCL2 is consumed by migrating inflammatory cells, which downregulate CCR2, as they cross the BBB.
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to define the cellular composition of ventricular, as compared with lumbar, cerebrospinal fluid (CSF) in patients with non-inflammatory neurological disorders (NIND). We addressed this issue by determining the cellular composition of lumbar CSF from patients with normal pressure hydrocephalus (NPH) who were undergoing lumbar CSF drainage during evaluation for shunting procedures, and evaluating ventricular CSF from a subset of these who underwent subsequent placement of ventriculoperitoneal shunts. We determined the cellular composition of lumbar CSF from 18 patients with NPH, and found that the leukocyte differentials, and relative proportions of CD4+ and CD8+ central memory (TCM), effector memory (TEM) and naive cell (TNaive) populations, were equivalent to those found previously in studies of CSF from patients with NIND. We further evaluated cells in the ventricular CSF of five patients who had previously undergone lumbar drainage. Leukocyte differential counts, as well as CD4+ and CD8+ TCM, TEM, and TNaive proportions, were equivalent in matched ventricular and lumbar CSF samples. These observations support the hypothesis that leukocytes enter the CSF in a selective fashion, at its site of formation in the choroid plexus. The results implicate CSF T cells in the immune surveillance of the central nervous system.
No preview · Article · Jul 2005 · Journal of Neuroimmunology
[Show abstract][Hide abstract] ABSTRACT: Expression of the chemokine receptor CCR4 is strongly associated with trafficking of specialized cutaneous memory T helper (Th) lymphocytes to the skin. However, it is unknown whether CCR4 itself participates in the development of cutaneous Th populations. We have addressed this issue via competitive bone marrow (BM) reconstitution assays; equal numbers of BM cells from CCR4(+/+) and CCR4(-/-) donors were allowed to develop side-by-side within RAG-1(-/-) hosts. Cells from both donor types developed equally well into B cells, naive CD8 T cells, naive CD4 T cells, interferon-gamma(+) Th1 cells, and interleukin-4(+) Th2 cells. In marked contrast, circulating cutaneous memory Th cells (i.e., E-selectin ligand(+) [E-lig(+)]) were more than fourfold more likely to be derived from CCR4(+/+) donors than from CCR4(-/-) donors. Most of this effect resides within the CD103(+) subset of the E-lig(+) Th population, in which donor CCR4(+/+) cells can outnumber CCR4(-/-) cells by >12-fold. No similar effect was observed for alpha4beta7(+) intestinal memory Th cells or CD103(+)/E-lig(-) Th cells. We conclude that CCR4 expression provides a competitive advantage to cutaneous Th cells, either by participating in their development from naive Th cells, or by preferentially maintaining them within the memory population over time.
Full-text · Article · Apr 2005 · Journal of Experimental Medicine