Hydrogen-rich water improves neurological functional recovery in experimental autoimmune encephalomyelitis mice

Highlights

• HRW reduced the clinical score of EAE.

• HRW altered EAE by inhibiting inflammatory infiltration and demyelination of CNS.

• HRW functions in EAE development largely by affecting the CD4⁺ population.

• HRW inhibiting Th17 cell differentiation in CNS and peripheral immune organs

Abstract

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease of the central nervous system (CNS). The high costs, inconvenient administration, and side effects of current Food and Drug Administration (FDA)-approved drugs often lead to poor adherence to the long-term treatment of MS. Molecular hydrogen (H₂) has been reported to exhibit anti-oxidant, anti-apoptotic, anti-inflammatory, anti-allergy, and anti-cancer effects. In the present study, we explored the prophylactic and therapeutic effects of hydrogen-rich water (HRW) on the progress of experimental autoimmune encephalomyelitis (EAE), the animal model for MS. We found that prophylactic administration of both 0.36 mM and 0.89 mM HRW was able to delay EAE onset and reduce maximum clinical scores. Moreover, 0.89 mM HRW also reduced disease severity, CNS infiltration, and demyelination when administered after the onset of disease. Furthermore, HRW treatment prevented infiltration of CD4⁺ T lymphocytes into the CNS and inhibited Th17 cell development without affecting Th1 cell populations. Because HRW is non-toxic, inexpensive, easily administered, and can readily cross the blood–brain barrier, our experiments suggest that HRW may have great potential in the treatment of MS.

Introduction

Multiple sclerosis (MS) is a chronic autoimmune disease characterized by multiple inflammatory demyelinating lesions in the central nervous system (CNS) (Frohman et al., 2006). Most MS patients initially experience relapsing–remitting neurological dysfunction, which develops into a secondary progressive form after 10–15 years (Lassmann et al., 2012). The disease cannot be cured by available treatments thus far, but a reduction of relapse rate and disease progression, as well as other clinical activity markers, e.g., magnetic resonance imaging (MRI) lesions and brain atrophy, can be achieved (Stangel et al., 2015).

Because inflammatory lesions detected by MRI can be up to ten-fold more common than clinically recognized attacks, persistent and long-term administration with disease modifying drugs (DMDs), which can reduce immune attacks and neural damage, has been proven to be an effective way to delay disease progression (Miller et al., 1998). However, current MS medications are not always affordable; common drugs to treat MS can cost as much as $60,000 a year. Some drugs require injecting the patient one or more times per week, and some have side effects that can be very serious. Moreover, the immune-suppressing drugs may cause long-term side effects (Castro-Borrero et al., 2012). The high costs, inconvenient administration, and side effects of these drugs often lead to poor adherence to long-term treatment.

Molecular hydrogen (H₂) is an anti-oxidant gas present within the human body. It is non-toxic, inexpensive, and easily administered by drinking hydrogen-rich water (HRW) (Xue et al., 2014). In recent years, H₂ has been reported to have great potential in preventive and therapeutic applications. Many experiments have been carried out to confirm the properties of H_2, which exhibits anti-oxidant, anti-apoptosis, anti-inflammation, and anti-allergy effects, among others (Zhang et al., 2012). It is reported that administering HRW for 33 days to brain slice cultures derived from mice significantly diminished superoxide formation compared to the control (Sato et al., 2008). In rats with periodontitis, oral intake of HRW for 4 weeks resulted in lowered serum levels of reactive oxygen species (ROS) and oxidized low-density lipoprotein-cholesterol (Ekuni et al., 2012). Inhalation of H₂ gas also protected the brain from ischemia and reperfusion-induced oxidative stress damage (Ohsawa et al., 2007). However, whether H₂ has therapeutic potential for MS has not been reported.

In the present study, we aimed to address the potential role of HRW on an animal model of MS, experimental autoimmune encephalomyelitis (EAE). We found that HRW can significantly reduce EAE severity. It also prevented infiltration of CD4⁺ T lymphocytes into the CNS and inhibited Th17 cell development. Our experiments suggest that HRW may have a novel potential in the treatment of MS.