Pomegranate peel extract ameliorates autoimmunity in animal models of multiple sclerosis and type 1 diabetes

- Pomegranate peel extract is rich in punicalin, punicalagin and ellagic acid.
- Pomegranate peel extract ameliorates experimental autoimmune encephalomyelitis.
- It prevents type 1 diabetes through inhibition of insulitis.
- Pomegranate peel extract inhibits interleukin-17 production.

Pomegranate peel extract (PPE) was obtained by aqueous-ethanol extraction and was abundant in punicalin, punicalagin and ellagic acid. As these compounds are known to act against inflammation and oxidative stress in synergistic fashion, effects of PPE were tested in vitro on immune cells and in animal models of multiple sclerosis and type 1 diabetes (T1D). In vitro, PPE inhibited interleukin-17 (IL-17) production from gut-associated lymphoid tissue (GALT) cells. PPE also reduced production of IL-17 in activated T cells isolated from animals with experimental autoimmune encephalomyelitis (EAE). It efficiently down-regulated clinical symptoms of EAE in DA rats and of streptozotocin-induced T1D in C57BL/6 mice. The effect of PPE in T1D was mediated by inhibition of immune cell infiltration into pancreatic islets and through interference with IL-17 and IFN-γ production in GALT. Our results suggest that PPE has the potential to be used as phytopharmaceutical for certain autoimmune and chronic inflammatory disorders.