CCR5(+) and CXCR3(+) T cells are increased in multiple sclerosis and their ligands MIP-1alpha and IP-10 are expressed in demyelinating brain lesions

Abstract

Multiple sclerosis (MS) is a T cell-dependent chronic inflammatory disease of the central nervous system. The role of chemokines in MS and its different stages is uncertain. Recent data suggest a bias in expression of chemokine receptors by Th1 vs. Th2 cells; human Th1 clones express CXCR3 and CCR5 and Th2 clones express CCR3 and CCR4. Chemokine receptors expressed by Th1 cells may be important in MS, as increased interferon-gamma (IFN-gamma) precedes clinical attacks, and IFN-gamma injection induces disease exacerbations. We found CXCR3(+) T cells increased in blood of relapsing-remitting MS, and both CCR5(+) and CXCR3(+) T cells increased in progressive MS compared with controls. Furthermore, peripheral blood CCR5(+) T cells secreted high levels of IFN-gamma. In the brain, the CCR5 ligand, MIP-1alpha, was strongly associated with microglia/macrophages, and the CXCR3 ligand, IP-10, was expressed by astrocytes in MS lesions but not unaffected white matter of control or MS subjects. Areas of plaque formation were infiltrated by CCR5-expressing and, to a lesser extent, CXCR3-expressing cells; Interleukin (IL)-18 and IFN-gamma were expressed in demyelinating lesions. No leukocyte expression of CCR3, CCR4, or six other chemokines, or anti-inflammatory cytokines IL-5, IL-10, IL-13, and transforming growth factor-beta was observed. Thus, chemokine receptor expression may be used for immunologic staging of MS and potentially for other chronic autoimmune/inflammatory processes such as rheumatoid arthritis, autoimmune diabetes, or chronic transplant rejection. Furthermore, these results provide a rationale for the use of agents that block CCR5 and/or CXCR3 as a therapeutic approach in the treatment of MS.

Figure 1

Separated PBMC from a progressive MS patient were stained with mAb and isotype control, as described in the text. Two-color flow cytometry analysis of 1 × 10⁴ cells from each sample was performed. The percentage of double-positive cells from the lymphocyte populations analyzed is shown. A shows staining with an isotype control (mouse IgG1-FITC and mouse IgG1-PE) that is the control for B (CD3⁺ CCR5⁺ cells) and C (CD3⁺ CXCR3⁺ cells). D represents staining with an isotype control (mouse IgG2a-FITC and mouse IgG1-PE) that is the control for E (CD3⁺ CCR3⁺ cells) and F (CD3⁺ CXCR4⁺ cells).

Figure 2

PBMC from a progressive MS patient were stained with mAb and isotype-matched control Ig, as described in the text. Two-color flow cytometry analysis of 1 × 10⁴ cells from each sample was performed. The percentage of double-positive cells from the lymphocyte populations analyzed is shown. A shows staining with an isotype control (mouse IgG1-FITC and mouse IgG1-PE) that is the control for B (CD4⁺ CCR5⁺ cells), C (CD8⁺ CCR5⁺ cells), D (CD4⁺ CXCR3⁺ cells), and E (CD8⁺ CXCR3⁺ cells).

Figure 3

Immunopathology of progressive MS illustrating chemokine and chemokine receptor expression within the CNS in an area of demyelination (Right). Left micrographs show the very limited expression of these proteins in normal brain, with focal expression of CCR5 by neurons, and IP-10 expression by astrocytes; only minor expression, comparable to normal brain, was seen in the uninvolved tissues of MS patients with inactive disease (not shown). In contrast, areas of demyelination showed dense surface staining of macrophages for MIP-1α (a and b). Macrophages and small numbers of lymphocytes in these areas showed corresponding expression of CCR1 (c and d) and CCR5 (e and f). Lesions contained dense IP-10 expression, associated with astrocytes and their tangled processes (g and h), plus small numbers of CXCR3⁺ lymphocytes (i and j). (Cryostat sections, hematoxylin counterstain, ×100.)