Our studies addressed the questions of how self-reactive T cells escape tolerance and what stimuli cause these T cells to initiate autoimmune responses. We employed experimental allergic encephalomyelitis (EAE) as an animal model of multiple sclerosis (MS). Endogenous expression of myelin basic protein (MBP) induces tolerance in T cells that recognize one region of MBP, whereas T cells specific for a different region escape tolerance. Triggers of disease induction were investigated in a T-cell receptor (TCR) transgenic model in which the majority of T cells recognize the MBP epitope that does not induce tolerance. EAE occurs spontaneously in this model and the incidence of disease depends on microbial exposure. EAE can also be actively induced by immunization with MBP peptide accompanied by injection of pertussis toxin as well as by administration of pertussis toxin alone. Immunization with MBP peptide without pertussis toxin, however, stimulates the transgenic T cells, but the activated T cells do not accumulate in the central nervous system (CNS) or induce EAE. Our studies suggest that initiation of autoimmune disease involves complex interactions between the neuroendocrine system as well as the innate and specific immune systems.
"Briefly, on day 0 (d0), female mice 8 to 10 weeks of age were injected subcutaneously into the right and left flanks with a total of 300 μg of MOG peptide in complete Freund’s adjuvant containing 300 μg Mycobacterium tuberculosis (DIFCO). Mice were also injected intraperitoneally with 500 ng pertussis toxin (List Laboratories) in phosphate buffered saline (PBS, Gibco/BRL) on d0 and d2 post-immunization (p.i.) to heighten the autoimmune reaction to MOG35-55 peptide [26,27]. "
[Show abstract][Hide abstract] ABSTRACT: Expression of chemokine CCL2 in the normal central nervous system (CNS) is nearly undetectable, but is significantly upregulated and drives neuroinflammation during experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis which is considered a contributing factor in the human disease. As astrocytes and brain microvascular endothelial cells (BMEC) forming the blood-brain barrier (BBB) are sources of CCL2 in EAE and other neuroinflammatory conditions, it is unclear if one or both CCL2 pools are critical to disease and by what mechanism(s).
Mice with selective CCL2 gene knockout (KO) in astrocytes (Astro KO) or endothelial cells (Endo KO) were used to evaluate the respective contributions of these sources to neuroinflammation, i.e., clinical disease progression, BBB damage, and parenchymal leukocyte invasion in a myelin oligodendrocyte glycoprotein peptide (MOG35-55)-induced EAE model. High-resolution 3-dimensional (3D) immunofluorescence confocal microscopy and colloidal gold immuno-electron microscopy were employed to confirm sites of CCL2 expression, and 3D immunofluorescence confocal microscopy utilized to assess inflammatory responses along the CNS microvasculature.
Cell-selective loss of CCL2 immunoreactivity was demonstrated in the respective KO mice. Compared to wild-type (WT) mice, Astro KO mice showed reduced EAE severity but similar onset, while Endo KO mice displayed near normal severity but significantly delayed onset. Neither of the KO mice showed deficits in T cell proliferation, or IL-17 and IFN-gamma production, following MOG35-55 exposure in vitro, or altered MOG-major histocompatibility complexclass II tetramer binding. 3D confocal imaging further revealed distinct actions of the two CCL2 pools in the CNS. Astro KOs lacked the CNS leukocyte penetration and disrupted immunostaining of CLN-5 at the BBB seen during early EAE in WT mice, while Endo KOs uniquely displayed leukocytes stalled in the microvascular lumen.
These results point to astrocyte and endothelial pools of CCL2 each regulating different stages of neuroinflammation in EAE, and carry implications for drug delivery in neuroinflammatory disease.
Journal of Neuroinflammation 01/2014; 11(1):10. DOI:10.1186/1742-2094-11-10 · 5.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent observations suggest a role for lymphocytes in human pancreatitis. However, existing animal models of pancreatitis are not immunologically based. In studies on major histocompatibility complex (MHC) II-deficient mice backcrossed five generations onto a C57BL/6 background, we discovered a progressive wasting disease due to pancreatic damage. The purpose of this study was to characterize this model of immune-based pancreatic injury.
The pathology was characterized histologically and functionally by assaying for pancreatic enzymes and glucose.
By 6 months, a periductal lymphocytic infiltrate was observed that later developed into pancreatic lesions with extensive, but selective, destruction of acinar cells. Mice eventually lost weight, developed a hunched appearance, and began to pass large, pale pellets. Histology of affected mice revealed pancreatic atrophy with almost complete loss of acinar cells, although islets remained intact. Serum levels of amylase, lipase, and glucose confirmed the selective loss of the exocrine pancreas, with both amylase and lipase levels being significantly decreased in affected mice. However, glucose levels remained unaffected. Adoptive transfer of splenic mononuclear cells to athymic mice was found to transfer the disease.
Aged MHC II-deficient mice develop an immune-based pancreatitis with selective loss of exocrine cells and function.
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