Prevention of multiple low-dose streptozotocin (MLD-STZ) diabetes in mice by an extract from gum resin of Boswellia serrata (BE)

In BK+/+ wild type mice, 5 days of daily treatment with 40 mg/kg STZ i.p. produced permanent increase of blood glucose, infiltration of lymphocytes into pancreatic islets (CD3-stain), apoptosis of periinsular cells (staining for activated caspase 3) after 10 days as well as shrinking of islet tissue after 35 days (H&E staining). This was associated with an increase of granulocyte colony stimulating factor (G-CSF), granulocyte/macrophage colony stimulating factor (GM-CSF) and proinflammatory cytokines (IL-1A, IL-1B, IL-2, IL-6, IFN-γ, TNF-α) in the blood. Whereas BE alone did not affect blood glucose in non diabetic mice, in STZ treated mice simultaneous i.p. injection of 150 mg/kg of BE over 10 days prevented animals from increase of blood glucose levels. Histochemical studies showed, that i.p. injection of 150 mg/kg BE for 10 days starting with STZ treatment, avoided lymphocyte infiltration into islets, apoptosis of periinsular cells and shrinking of islet size 35 days after STZ. As far as the cytokines tested are concerned, there was a significant inhibition of the increase of G-CSF and GM-CSF. BE also significantly prevented the increase of IL-1A, IL-1B, IL-2, IL-6, IFN-γ and TNF-α. It is concluded that extracts from the gum resin of Boswellia serrata prevent islet destruction and consequent hyperglycemia in an animal model of type 1 diabetes probably by inhibition of the production/action of cytokines related to induction of islet inflammation in an autoimmune process.