Activated T-cells and macrophages in the cerebrospinal fluid and the spinal meningeal exudate in chronic relapsing experimental allergic encephalomyelitis

The cerebrospinal fluid immune cell landscape in animal models of multiple sclerosis

The fluid compartment surrounding the central nervous system (CNS) is a unique source of immune cells capable of reflecting the pathophysiology of neurologic diseases. While human clinical and experimental studies often employ cerebrospinal fluid (CSF) analysis, assessment of CSF in animal models of disease are wholly uncommon, particularly in examining the cellular component. Barriers to routine assessment of CSF in animal models of multiple sclerosis (MS) include limited sample volume, blood contamination, and lack of feasible longitudinal approaches. The few studies characterizing CSF immune cells in animal models of MS are largely outdated, but recent work employing transcriptomics have been used to explore new concepts in CNS inflammation and MS. Absence of extensive CSF data from rodent and other systems has curbed the overall impact of experimental models of MS. Future approaches, including examination of CSF myeloid subsets, single cell transcriptomics incorporating antigen receptor sequencing, and use of diverse animal models, may serve to overcome current limitations and provide critical insights into the pathogenesis of, and therapeutic developments for, MS.

Treatment of murine experimental autoimmune encephalomyelitis with a myelin basic protein peptide analog alters the cellular composition of leukocytes infiltrating the cerebrospinal fluid

Experimental autoimmune encephalomyelitis (EAE) can be effectively treated during disease exacerbation by administration of a peptide corresponding to the major T cell epitope of myelin basic protein (MBP), but the mechanism by which T cell tolerance leads to clinical improvement is not well-defined. Acute exacerbations of EAE are accompanied by an infiltration of blood-borne leukocytes into the brain and spinal cord, where they mediate inflammation and demyelination. To investigate peptide effects on infiltrating cells, we collected cerebrospinal fluid (CSF) from (PL/JxSJL)F1 mice with MBP-induced EAE. Pleiocytosis by lymphocytes, neutrophils, and macrophages was seen throughout the course of relapsing-remitting disease. A single administration of the MBP peptide analog, Ac1-11[4Y], reduced disease severity, accompanied by a dramatic and selective loss of neutrophil pleiocytosis. A longer course of peptide therapy resulted in complete recovery from clinical signs of disease, and decreased pleiocytosis by all cell types. Clinical severity throughout the course of disease and therapy was directly related to the degree of infiltration by neutrophils and macrophages, and the clinical improvement following peptide therapy was accompanied by decreased central nervous system (CNS) expression of chemoattractants for these cell types. These observations support a model of disease exacerbation mediated by phagocytic cellular infiltration under the ultimate control of T cell-derived factors, amenable to treatment by down-regulation of the T cell activation state.

Immune mechanisms in the pathogenesis of demyelinating diseases

The loss of myelin which characterises many human and experimental demyelinating diseases, among them multiple sclerosis, is thought to be immune mediated, but the precise mechanisms responsible remain unknown despite intense research. Normally, myelin in the central nervous system (CNS) is protected from systemic immune responses by the blood brain barrier, which separates nervous tissue from the peripheral circulation. Here we review evidence suggesting that an understanding of the demyelinating disorders may be helped by considering their immune pathogenesis in two stages. The first is damage to the blood brain barrier; this appears to be cell mediated, and allows infiltration into the CNS of other immune effectors. These include complement and also macrophages, which together may mediate the second stage, injury to the myelin/oligodendrocyte complex.