Paeoniflorin (PF), a herb component used in Chinese medicine, improved symptoms and reduced inflammation in a mouse model that recapitulates the human features of multiple sclerosis (MS).
The study, “Paeoniflorin Ameliorates Experimental Autoimmune Encephalomyelitis via Inhibition of Dendritic Cell Function and Th17 Cell Differentiation”, appeared in the journal Scientific Reports.
PF is one of the principal bioactive components of the Paeonia lactiflora root (baishao in Chinese), a commonly used herb in traditional Chinese medicine.
“It has been reported that PF exhibits multiple effects, such as anti-inflammation, immunoregulation, anti-arthritis, anti-hepatitis, pain-relieving, neuroprotection and anti-hyperglycemia,” the researchers wrote.
However, until now, PF’s effect on MS had remained unknown. In the present study, researchers investigated the action of PF using an animal model for MS, the experimental autoimmune encephalomyelitis (EAE) model.
Mice were injected intraperitoneally (i.e., within or into the peritoneal cavity) with either phosphate-buffered saline (control) or PF (5 mg/kg) before EAE induction. The team observed that PF treatment ameliorated disease symptoms and significantly decreased the onset of EAE in the animals.
To further assess PF’s anti-inflammatory properties, researchers analyzed what changed in the mice central nervous system (CNS), specifically in spinal cord tissue. Compared to controls, PF treatment reduced infiltration of inflammatory cells and demyelination (loss of myelin, the protective coat of neurons) in EAE mice, the two major manifestations of MS.
Researchers then investigated the mechanism underlying PF’s anti-inflammatory properties and found that PF ameliorates inflammation of EAE by decreasing the number of Th17 cells infiltrated in mice CNS and spleen. The Th17 cells have been shown to play a seminal role in tissue inflammation in MS.
PF’s action, however, was not on Th17 cells directly. Instead, researchers showed that PF suppressed the production of key cytokines, namely interleukin-6 (IL-6), by dendritic cells (a type of immune cell). Cytokines are key signaling molecules that mediate and regulate inflammation. This led to a decreased inflammatory response induced by Th17 cells.
Overall, the study “demonstrated that PF treatment can effectively improve the clinical symptoms and delay the disease onset in EAE”, researchers wrote. PF decreased IL-6 production by dendritic cells, culminating in a reduction of the inflammatory response perpetrated by Th17 cells.
“Our study provided insights into the role of PF as a unique therapeutic agent for the treatment of multiple sclerosis,” the team concluded.