Salivary glands can be protected during radiotherapy

The work, which was directed by Dr Yun-Sil Lee from the Korea Institute of Radiological and Medical Sciences in Seoul, Korea, found that targeted overexpression of heat shock protein 25 prevents radiation-induced damage to salivary glands during irradiation. Salivary dysfunction may involve dry mouth, oral infections, dental caries, and difficulty eating, some of which persist long after treatment ends, even permanently.

Dr Yun-Sil Lee and colleagues examined whether salivary glands could be protected by heat shock proteins (HSPs), which are expressed by cells in an effort to counteract environmental stressors such as heat, hypoxia, and ionizing radiation. Using adenoviral vectors, the researchers specifically overexpressed HSP25 and HSP70i in submandibular salivary glands of rats. Rat salivary glands were then irradiated and monitored for radiation-induced changes.

In treated rats, HSP25 protected salivary gland function by maintaining gland weight, salivary flow rate, and salivary fluid composition, whereas HSP70i significantly protected only salivary flow rate. When specific damage to the glands was assessed, HSP25 and HSP70i both greatly diminished scarring, nuclear damage, and cell death (apoptosis), but HSP70i was slightly less effective. Finally, HSP25 and HSP70i preserved expression of aquaporin 5, which is important for water transport in salivary glands.

The scientists have concluded that HSP25 delivery may represent a novel means of preventing the collateral damage associated with radiation therapy.