Background

Background: Multiple Sclerosis (MS) is an immune mediated disease of the central nervous system (CNS). Epstein-Barr virus (EBV) is among the most well-established environmental risk factors in MS. MS patients also make low affinity antibodies against neurotrophic viruses such as measles (M), rubella (R), and zoster (Z), and they make these intrathecally. This phenomenon is quite specific for MS and it is called MRZ reaction. The pathophysiological role of MRZ reaction currently remains unclear.

Objectives

Objectives: Because EBV induces differentiation of infected B cells in antigen-nonspecific manner, the aim of this project is to test the hypothesis that the extent of MRZ reaction correlates with the amount of EBV infected B cells in the intrathecal compartment of MS patients and with the MS severity.

Methods

Methods: In a pilot cohort of 80 patients with broad range of MS severity, we blindly analyzed MRZ reaction by enzyme-linked immunosorbent assay (ELISA) applied to matched cerebrospinal fluid (CSF) and serum samples. To derive a single measure of the extent of MRZ reaction, we summed antibody indexes (AI) for each reaction component (M, R and Z) to MRZ score.

Results

Results: Upon unblinding the MS severity outcomes and diagnostic subgroups, the MRZ scores did not significantly correlate with B cell/plasma cell biomarkers known to be increased in MS CSF (i.e., B-cell maturation antigen/BCMA and IgG index) and were not significantly different between relapsing remitting, primary progressive and secondary progressive MS. Finally, the MRZ scores did not correlate with clinical outcomes of MS severity (MS disease severity scale: MS-DSS and brain damage severity: principal component of brain parenchymal fraction and the symbol digit modalities test normalized for patient’s age).

Conclusions

Conclusions: The study proved null hypothesis (i.e., MRZ reaction is not associated with intrathecal biomarkers of B cell/plasma cell expansion and with MS severity). The association between MRZ reaction and MS remains a mystery.

Acknowledgments: The research was supported by the Intramural Research Program of the NIH, NIAID.

Notice: This study involved patients and it was approved by NIAID IRB.

Background

Multiple sclerosis (MS) is a chronic neuroinflammatory disorder, in which activated immune cells directly or indirectly induce demyelination and axonal degradation. Inflammatory stimuli also change phenotype of astrocytes, making them neurotoxic. Resulting “toxic astrocyte” phenotype has been seen in animal models of neuroinflammation and in MS lesions. Proteins secreted by toxic astrocytes are elevated in the cerebrospinal fluid (CSF) of MS patients and reproducibly correlate with the rates of accumulation of neurological disability and brain atrophy. This suggests pathogenic role for toxic astrocytes in MS.

Objectives

Therefore, the goal of this study is to identify signaling pathways underlying induction of toxic astrogliosis and to detect therapeutic inhibitors for these processes.

Methods

Here we applied commercial library of small molecules (Selleck Chemicals LLC; 1431 drugs) that are either Food and Drug Administration (FDA) approved or in clinical development to an in vitro model of toxic astrogliosis to identify drugs and signaling pathways that inhibit inflammatory transformation of astrocytes to neuro-toxic phenotype.

Results

Inhibitors of three pathways related to the endoplasmic reticulum (ER) stress: 1. Proteasome, 2. Heat shock protein 90 (HSP90)- and 3. Mammalian target of rapamycin (mTOR) reproducibly decreased inflammation-induced conversion of astrocytes to toxic phenotype. Dantrolene, an anti-spasticity drug that inhibits calcium release through ryanodine receptors (RyR) expressed in the ER of CNS cells, also exerted inhibitory effect at in vivo-achievable concentrations. We also established CSF SERPINA3 as a relevant pharmacodynamic marker for inhibiting toxic astrocytes in clinical trials.

Conclusions

In conclusion, drug library screening provides mechanistic insight into generation of toxic astrocytes and identifies candidates for immediate proof-of-principle clinical trial(s).

Background

Multiple sclerosis (MS) is a chronic neuroinflammatory disorder, in which activated immune cells directly or indirectly induce demyelination and axonal degradation. Inflammatory stimuli also change phenotype of astrocytes, making them neurotoxic. Resulting “toxic astrocyte” phenotype has been seen in animal models of neuroinflammation and in MS lesions. Proteins secreted by toxic astrocytes are elevated in the cerebrospinal fluid (CSF) of MS patients and reproducibly correlate with the rates of accumulation of neurological disability and brain atrophy. This suggests pathogenic role for toxic astrocytes in MS.

Objectives

Therefore, the goal of this study is to identify signaling pathways underlying induction of toxic astrogliosis and to detect therapeutic inhibitors for these processes.

Methods

Here we applied commercial library of small molecules (Selleck Chemicals LLC; 1431 drugs) that are either Food and Drug Administration (FDA) approved or in clinical development to an in vitro model of toxic astrogliosis to identify drugs and signaling pathways that inhibit inflammatory transformation of astrocytes to neuro-toxic phenotype.

Results

Inhibitors of three pathways related to the endoplasmic reticulum (ER) stress: 1. Proteasome, 2. Heat shock protein 90 (HSP90)- and 3. Mammalian target of rapamycin (mTOR) reproducibly decreased inflammation-induced conversion of astrocytes to toxic phenotype. Dantrolene, an anti-spasticity drug that inhibits calcium release through ryanodine receptors (RyR) expressed in the ER of CNS cells, also exerted inhibitory effect at in vivo-achievable concentrations. We also established CSF SERPINA3 as a relevant pharmacodynamic marker for inhibiting toxic astrocytes in clinical trials.

Conclusions

In conclusion, drug library screening provides mechanistic insight into generation of toxic astrocytes and identifies candidates for immediate proof-of-principle clinical trial(s).