Human Brain Microvascular Endothelial Cells and Umbilical Vein Endothelial Cells Differentially Facilitate Leukocyte Recruitment and Utilize Chemokines for T Cell Migration

Endothelial cells that functionally express blood brain barrier (BBB) properties are useful surrogates for studying leukocyte-endothelial cell interactions at the BBB. In this study, we compared two different endothelial cellular models: transfected human brain microvascular endothelial cells (THBMECs) and human umbilical vein endothelial cells (HUVECs). With each grow under optimal conditions, confluent THBMEC cultures showed continuous occludin and ZO-1 immunoreactivity, while HUVEC cultures exhibited punctate ZO-1 expression at sites of cell-cell contact only. Confluent THBMEC cultures on 24-well collagen-coated transwell inserts had significantly higher transendothelial electrical resistance (TEER) and lower solute permeability than HUVECs. Confluent THBMECs were more restrictive for mononuclear cell migration than HUVECs. Only THBMECs utilized abluminal CCL5 to facilitate T-lymphocyte migration in vitro although both THBMECs and HUVECs employed CCL3 to facilitate T cell migration. These data establish baseline conditions for using THBMECs to develop in vitro BBB models for studying leukocyte-endothelial interactions during neuroinflammation

Human cerebrospinal fluid contains CD4+ memory T cells expressing gut- or skin-specific trafficking determinants: relevance for immunotherapy

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Results</p> <p>The expression of cutaneous leukocyte antigen (CLA) and CC-chemokine receptor 4 (CCR4; associated with skin-homing) as well as the expression of integrin α4β7 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 α4β7 and CCR9 as paired blood samples.</p> <p>Conclusion</p> <p>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 <it>via </it>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.</p

Chemokine Receptors as Biomarkers in Multiple Sclerosis

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