Pituitary adenylate cyclase-activating polypeptide (PACAP) ameliorates experimental autoimmune encephalomyelitis by suppressing the functions of antigen presenting cells

Abstract

Pituitary adenylate cyclase-activating polypeptide (PACAP), a 38-amino acid neuropeptide belonging to the secretin-glucagon-vasoactive intestinal peptide (VIP) family, performs a variety of functions in both the nervous and immune systems. In this study, we examined the effects of PACAP on experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. When administrated intraperitoneally every other day after immunization with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55, PACAP ameliorated both the clinical and pathological manifestations of EAE Ex vivo examination revealed a significant inhibition of MOG35-55-specific Th1 response in mice treated with PACAP. In vitro analysis revealed that PACAP suppressed the production of inflammatory cytokines, including TNF-alpha, IL-1beta, and IL-12, and expression of the costimulatory factor B7-2 on macrophage and microglia, which may function as antigen presenting cells (APC) in the CNS. While PACAP suppressed the differentiation of MOG35-55-specific T cells into Th1 effectors upon restimulation with MOG35-55-expressing APC, it did not affect interferon (IFN)-gamma production by MOG35-55-specific T cells stimulated with anti-CD3 and anti-CD28. These observations suggested that PACAP suppressed induction of EAE primarily via suppression of APC function and inflammatory cytokine production. PACAP may be useful in the future treatment of Th1-mediated autoimmune diseases, such as multiple sclerosis.

Inhibition of midkine alleviates experimental autoimmune encephalomyelitis through the expansion of regulatory T cell population

“…To examine the immunological roles of MK, we generated MOG -induced EAE in C57BL/6J WT and MK-deficient (Mdk Ϫ/Ϫ ) mice. Most of the WT mice exhibited clinical signs of the disease Ϸ12 days after the initial immunization and developed peak EAE Ϸ18 days after immunization as described previously (20,21). Almost all of the Mdk Ϫ/Ϫ mice also developed EAE.…”

“…To evaluate T cell proliferation, purified CD4 ϩ CD25 ϩ T cells isolated from the spleens of peak EAE mice were cultured at different ratios (0.1:1, 0.3:1, and 1:1) with CD4 ϩ CD25 Ϫ T cells in the presence of mitomycin C-treated feeder cells (5 ϫ 10 6 cells per well) and 20 ng/ml MOG35-55 for 3 days. T cell proliferation was assessed by using a mouse IL-2 ELISA kit (BD Pharmingen) as described previously (20).…”

“…Purified CD4 ϩ T cells (2 ϫ 10 5 cells per well) isolated from the spleens or CNS of peak EAE mice were cultured with mitomycin C-treated feeder cells (5 ϫ 10 6 cells per well) in the presence of 20 ng/ml MOG35-55 for 1, 3, and 5 days. The concentrations of IL-17, IFN-␥, and IL-4 in the culture supernatant were assessed by using the corresponding cytokine-specific ELISA kits (IL-17, R & D Systems; IFN-␥ and IL-4, BD Pharmingen) as described previously (20). To examine the effect of MK on the Treg cell population, cells stimulated with 20 ng/ml MOG35-55 for 3 days in the presence of 0, 20, or 100 ng/ml MK were analyzed by flow cytometry.…”

Chronological Changes of CD4+ and CD8+ T Cell Subsets in the Experimental Autoimmune Encephalomyelitis, a Mouse Model of Multiple Sclerosis

“…EAE was induced as described previously (Kato et al 2004;Takeuchi et al 2006). Briefl y, C57BL/6J mice aged 8 weeks were immunized subcutaneously at the base of the tail with 0.2 ml of emulsion containing 200 μ g MOG in phosphate buffered saline (PBS) combined with an equal volume of IFA containing 300 μ g heat-killed Mycobacterium Tuberculosis H37Ra.…”

PACAP as a Potential Biomarker: Alterations of PACAP Levels in Human Physiological and Pathological Conditions

“…Administration of PACAP suppressed experimental autoimmune encephalomyelitis, a model of multiple sclerosis [ 33 ]. Studies in mice supported these observations by showing that PACAP knockout mice exhibited exacerbated encephalomyelitis, thus, the endogenous production of the peptide protects against multiple sclerosis, probably by modulating regulatory T cells [ 34 , 35 ].…”