Kevin J. Kennedy

MIP-1alpha and MCP-1 differentially regulate acute and relapsing autoimmune encephalomyelitis as well as Th1/Th2 lymphocyte differentiation.

Chemokines are a family of small‐molecular‐weight cytokines that induce chemotaxis and chemokinesis of leukocytes. These molecules are ligands for seven‐transmembrane, G‐protein‐linked receptors and are known to activate integrins on the surface of leukocytes and other cells as well as induce a number of signaling events. They play a significant role in the migration of leukocytes from blood into tissue during inflammatory processes. We tested the role of chemokines in experimental autoimmune encephalomyelitis (EAE) and found that macrophage inflammatory protein‐1α (MlP‐1α) correlated with acute disease development, whereas monocyte chemotactic protein‐1 (MCP‐1) did not. In contrast, MCP‐1 production in the central nervous system correlated with relapsing EAE development. Moreover, anti‐MIP‐1α, but not anti‐MCP‐1, inhibited development of acute but not relapsing EAE, whereas anti‐MCP‐1 significantly reduced the severity of relapsing EAE. To test the effects of chemokines on the differentiation of naive T cells, TCR transgenic splenic T cells (Tg+ T cells) from DO11.10 OVA TCR transgenic mice were used as a source of Th0 cells and were stimulated with specific anti‐clonotypic monoclonal antibodies in the presence of MIP‐1α, MCP‐1, or controls. MIP‐1α drove Th0 cells to differentiate to Th1, whereas MCP‐1 drove Th0 cells to differentiate to Th2. Similarly, MCP‐1, but not MlP‐1α significantly inhibited the adoptive transfer of EAE when included in in vitro activation cultures, further suggesting a regulatory anti‐inflammatory property. These results suggest a differential role for CC chemokines in the development and activation of T cells during autoimmune inflammatory diseases. J. Leukoc. Biol.62: 681–687; 1997.

Acute and relapsing experimental autoimmune encephalomyelitis are regulated by differential expression of the CC chemokines macrophage inflammatory protein-1α and monocyte chemotactic protein-1

Experimental autoimmune encephalomyelitis (EAE) is a T lymphocyte-mediated disease of the central nervous system (CNS), characterized by mononuclear cell infiltration and demyelination resulting in paralysis. We examined CC chemokine expression in the CNS throughout the entire course of the disease and found that the production of macrophage inflammatory protein (MIP)-1alpha correlated with increasing acute disease severity and remained elevated throughout chronic, relapsing disease. In contrast, a substantial level of monocyte chemotactic protein (MCP)-1 expression was not observed until late in acute disease and continued to be evident in the relapsing phase of the disease. MCP-1 expression correlated with increasing severity of clinical relapses. Lower levels of RANTES in the CNS were noted throughout the disease course, but showed little correlation with either acute or relapsing disease. Although RANTES expression was observed during the entire course of disease, anti-RANTES treatment had no effect on clinical disease progression. Anti-MCP-1, but not anti-MIP-1alpha, treatment during relapsing EAE decreased clinical severity of relapsing disease. Furthermore, anti-MCP-1 treatment reduced CNS macrophage accumulation during relapsing EAE. These results suggest that MIP-1alpha controls mononuclear cell accumulation during acute EAE, while MCP-1 controls mononuclear cell infiltration during relapsing EAE.

CXL10 (IFN-γ-inducible protein-10) control of encephalitogenic CD4+ T cell accumulation in the central nervous system during experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a CD4+ Th1-mediated demyelinating disease of the CNS that serves as a model for multiple sclerosis. A critical event in the pathogenesis of EAE is the entry of both Ag-specific and Ag-nonspecific T lymphocytes into the CNS. In the present report, we investigated the role of the CXC chemokine CXCL10 (IFN-γ-inducible protein-10) in the pathogenesis of EAE. Production of CXCL10 in the CNS correlated with the development of clinical disease. Administration of anti-CXCL10 decreased clinical and histological disease incidence, severity, as well as infiltration of mononuclear cells into the CNS. Anti-CXCL10 specifically decreased the accumulation of encephalitogenic PLP139–151 Ag-specific CD4+ T cells in the CNS compared with control-treated animals. Anti-CXCL10 administration did not affect the activation of encephalitogenic T cells as measured by Ag-specific proliferation and the ability to adoptively transfer EAE. These results demonstrate an important role for the CXC chemokine CXCL10 in the recruitment and accumulation of inflammatory mononuclear cells during the pathogenesis of EAE.

Role of Chemokines in the Regulation of Th1/Th2 and Autoimmune Encephalomyelitis

Chemokines are low molecular weight chemotactic peptides that bind seven transmembrane-spanning, G protein-coupled receptors and deliver signals leading to T cell costimulation, hematopoeisis, cytokine expression, T cell differentiation, and integrin activation. Experimental autoimmune encephalomyelitis (EAE) is a CD4+ Th1-mediated demyelinating disease of the central nervous system (CNS) that serves as a model for multiple sclerosis (MS). A hallmark in the pathogenesis of this CNS demyelinating disease is the emigration of T cells and monocytes from the blood to the CNS. There are several considerations that suggest a role for chemokines in the influx of inflammatory cells and the resulting disease process including a tight temporal expression pattern with relationship to disease activity and prevention of disease development by in vivo neutralization. We review the evidence that temporal and spatial expressions of chemokines are crucial factors, complementing adhesion molecule upregulation, that regulate EAE and potentially MS disease activity as well as the functions of chemokines in Th1 and Th2 biology.

Inhibition of relapsing experimental autoimmune encephalomyelitis in SJL mice by feeding the immunodominant PLP139-151 peptide

Peripheral antigen‐specific tolerance can be induced by feeding protein antigens. The mechanism has been described as either clonal anergy/deletion or induction of antigen‐specific regulatory cells that produce transforming growth factor‐β (TGF‐β). These two mechanisms have been linked to the magnitude and frequency of the dose of antigen fed; a single high dose induces anergy/deletion, whereas multiple low doses of antigen induce TGF‐β‐secreting regulatory cells. In the present study, we investigated the mechanisms of feeding soluble peptides of proteolipid protein (PLP) for prevention of experimental autoimmune encephalomyelitis (EAE) induced by either intact PLP or the immunodominant PLP139‐151 peptide. Feeding PLP139‐151 prevented acute and relapsing EAE induced by either PLP139‐151 or intact PLP. PLP139‐151 feeding induced anergy in the T helper 1 (Th1) population as measured by an inhibition of both proliferation and interferon‐γ (IFN‐γ) production. Interleukin‐4 (IL‐4) production was increased, but increased TGF‐β production was not observed. Importantly, PLP139‐151 feeding induced anergy in peripheral and central system (CNS)‐infiltrating T cells. Feeding of the subdominant PLP epitope (PLP178‐191) failed to inhibit EAE induced by PLP139‐151; therefore, oral tolerance was not due to induction of bystander suppression. These results demonstrate that both acute and relapsing paralysis in EAE can be prevented by feeding the immunodominant peptide of PLP.

Transgenic expression of CCL2 in the central nervous system prevents experimental autoimmune encephalomyelitis

CC chemokine ligand 2 (CCL2)/monocyte chemotactic protein‐1, a member of the CC chemokine family, is a chemoattractant for monocytes and T cells through interaction with its receptor CCR2. In the present study, we examined a T helper cell type 1 (Th1)‐dependent disease, proteolipid protein‐induced experimental autoimmune encephalomyelitis, in a transgenic mouse line that constitutively expressed low levels of CCL2 in the central nervous system (CNS) under control of the astrocyte‐specific glial fibrillary acidic protein promoter. CCL2 transgenic mice developed significantly milder clinical disease than littermate controls. As determined by flow cytometry, mononuclear cell infiltrates in the CNS tissues of CCL2 transgenic and littermate‐control mice contained equal numbers of CD4+ and CD8+ T cells, and the CCL2 transgenic mice showed an enhanced number of CNS‐infiltrating monocytes. CNS antigen‐specific T cells from CCL2 transgenic mice produced markedly less interferon‐γ. Overexpression of CCL2 in the CNS resulted in decreased interleukin‐12 receptor expression by antigen‐specific T cells. Collectively, these results indicate that sustained, tissue‐specific expression of CCL2 in vivo down‐regulates the Th1 autoimmune response, culminating in milder clinical disease.

Regulation of experimental autoimmune encephalomyelitis by chemokines and chemokine receptors.

Experimental autoimmune encephalomyelitis (EAE) isa, T cell mediated demyelinating disease of the central nervous system (CNS) that serves as a model for multiple sclerosis (MS). In sights into the pathogenesis of this model may help scientists understand the human disease and aid in rational drug discovery. In this review we summarize the role of chemokines and chemokine receptors in disease pathogenesis and suggest a pathway of events that leads to demyelination and subsequent clinical disease manifestation.

Immunoneutralization of chemokines for the prevention and treatment of central nervous system autoimmune disease.

Chemokine-induced lymphocyte migration has long been hypothesized to regulate the appearance and continued presence of lymphocytes and monocytes in tissue-specific autoimmune diseases, including central nervous system autoimmune diseases such as multiple sclerosis. For instance, a large body of evidence points to the temporal association of chemokine expression with the appearance of T lymphocytes and monocytes/macrophages. Furthermore, experiments using mice with targeted mutations for chemokines have shown the importance of those molecules in the development of central nervous system autoimmune disease. We have hypothesized that temporal and spatial expression of chemokines is a key factor in the pathogenesis of experimental autoimmune encephalomyelitis and multiple sclerosis. To test our hypothesis we have employed the strategy of eliminating chemokine function by the passive transfer of chemokine-specific polyclonal antibodies. This approach has allowed us not only to test the function of chemokines in experimental autoimmune encephalomyelitis development, but also to ask questions about the roles of chemokines during disease progression. Moreover, this approach has allowed us to assess the efficacy of targeting chemokines and their receptors for treatment of ongoing disease. In the present report we summarize our experience using anti-chemokine administration for the prevention and treatment of experimental autoimmune encephalomyelitis as well as provide specific examples of how this approach is efficacious for disease treatment.

Anti-CCL2 treatment inhibits Theiler’s murine encephalomyelitis virus-induced demyelinating disease

Theiler’s murine encephalomyelitis virus induces a demyelinating disease (TMEV-IDD) of the central nervous system (CNS) in susceptible mouse strains with accompanying histopathology characterized by mononuclear cell infiltrates. In susceptible strains of mice such as SJL, virus establishes a persistent infection in macrophages, induces a CNS infiltration by macrophages, T cells, and B cells, which results in chronic-progressive paralysis. In the present report the authors have investigated the functional role of CCL2 (monocyte chemotactic protein-1) in the induction and progression of demyelinating disease. Treatment of infected mice at day 0, 14, or 28 with anti-CCL2 resulted in a significant decrease in the clinical disease progression. Further analysis of anti-CCL2-treated mice revealed decreased CNS inflammation and mononuclear cell infiltration with an accompanying change in inflammatory cytokine responses. There was an overall decrease in the absolute numbers of CNS-infiltrating CD4+ T cells, macrophages, and B cells. Finally, anti-CCL2 treatment resulted in decreased viral load in the CNS. These data directly demonstrate a role for CCL2 in the pathogenesis of TMEV-IDD.