IFNβ therapy progressively normalizes the increased ex vivo T lymphocyte apoptosis observed in active patients with multiple sclerosis

Activation-induced cell death in T lymphocytes from multiple sclerosis patients

Apoptosis is a major mechanism regulating immune tolerance by the elimination of autoreactive T lymphocytes. A failure of activation induced cell-death (AICD) has been described in T lymphocytes from patients with multiple sclerosis (MS). The aims of this study were to evaluate AICD in T lymphocytes from patients with MS and healthy controls, and to explore the molecular mechanisms underlying the deregulation observed in apoptosis induction. PHA-induced AICD was reduced in T lymphocytes from patients with relapsing-remitting MS compared with controls. This finding was associated with a diminished expression of Fas and a failure in caspase 3 activation.

Theiler's virus infection: Pathophysiology of demyelination and neurodegeneration

Multiple sclerosis (MS) has been suggested to be an autoimmune demyelinating disease of the central nervous system (CNS), whose primary target is either myelin itself, or myelin-forming cells, the oligodendrocytes. Although axonal damage occurs in MS, it is regarded as a secondary event to the myelin damage. Here, the lesion develops from the myelin (outside) to the axons (inside) "Outside-In model". The Outside-In model has been supported by an autoimmune model for MS, experimental autoimmune (allergic) encephalomyelitis (EAE). However, recently, (1) EAE-like disease has also been shown to be induced by immune responses against axons, and (2) immune responses against axons and neurons as well as neurodegeneration independent of inflammatory demyelination have been reported in MS, which can not be explained by the Outside-In model. Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD) is a viral model for MS. In TMEV infection, axonal injury precedes demyelination, where the lesion develops from the axons (inside) to the myelin (outside) "Inside-Out model". The initial axonal damage could result in the release of neuroantigens, inducing autoimmune responses against myelin antigens, which potentially attack the myelin from outside the nerve fiber. Thus, the Inside-Out and Outside-In models can make a "vicious" immunological cycle or initiate an immune cascade.

Increase of Ki-67+ natural killer cells in multiple sclerosis patients treated with interferon-β and interferon-β combined with low-dose oral steroids

Interferon-β (IFN-β) is known to expand regulatory CD56(bright) natural killer (NK) cells in multiple sclerosis (MS). In this cross-sectional study we show that MS patients treated with IFN-β alone or in combination with low-dose prednisolone displayed increased proportion of all NK cell subsets in the active phase of the cell cycle (Ki-67+). There was no difference in NK cell apoptosis markers. In vitro experiments showed that both IFN-β and IFN-β in combination with corticosteroids increased the proportion of Ki-67(+) NK cells. This study, although limited, shows that treatment with IFN-β affects NK cell cycle without altering NK cell apoptosis in MS patients.

Excessive biologic response to IFNβ is associated with poor treatment response in patients with multiple sclerosis

BACKGROUND

Interferon-beta (IFNβ) is used to inhibit disease activity in multiple sclerosis (MS), but its mechanisms of action are incompletely understood, individual treatment response varies, and biological markers predicting response to treatment have yet to be identified.

METHODS

The relationship between the molecular response to IFNβ and treatment response was determined in 85 patients using a longitudinal design in which treatment effect was categorized by brain magnetic resonance imaging as good (n = 70) or poor response (n = 15). Molecular response was quantified using a customized cDNA macroarray assay for 166 IFN-regulated genes (IRGs).

RESULTS

The molecular response to IFNβ differed significantly between patients in the pattern and number of regulated genes. The molecular response was strikingly stable for individuals for as long as 24 months, however, suggesting an individual 'IFN response fingerprint'. Unexpectedly, patients with poor response showed an exaggerated molecular response. IRG induction ratios demonstrated an exaggerated molecular response at both the first and 6-month IFNβ injections.

CONCLUSION

MS patients exhibit individually unique but temporally stable biological responses to IFNβ. Poor treatment response is not explained by the duration of biological effects or the specific genes induced. Rather, individuals with poor treatment response have a generally exaggerated biological response to type 1 IFN injections. We hypothesize that the molecular response to type I IFN identifies a pathogenetically distinct subset of MS patients whose disease is driven in part by innate immunity. The findings suggest a strategy for biologically based, rational use of IFNβ for individual MS patients.