Mucus-normalizing activity of a fixed thyme and primula extract combination: Reduction of LPS-induced goblet cell metaplasia and mucin production in vivo

Aim: Increased secretion of viscous mucus is a hallmark symptom of acute bronchitis. Using an in vivo model of bronchoalveolitis we aimed to investigate whether Bronchipret ® film-coated tablets (BRO) possess the ability to positively regulate determinants of mucus secretion and consistency. BRO is a herbal medicinal product containing the fixed combination of thyme herb and primula root extract and is clinically used for the treatment of acute bronchitis. Methods: Bronchoalveolitis was induced in male Wistar rats by intratracheal LPS instillation (100 µg/animal). BRO was given daily at 1-10-fold equivalents of the human daily dose (68-680 mg/kg) for up to three days. Animals were sacrificed at 24h intervals up to 72h post LPS challenge to analyze epithelial goblet cell numbers as well as MUC5AC protein expression in lung tissue homogenate. Results: LPS increased both the density of bronchial epithelial goblet cells as well as pulmonary MUC5AC concentration in a time-dependent fashion with the highest levels reached at 72h post LPS administration. Treatment with BRO at all dose levels led to a significant reduction in MUC5AC at 48h and 72h as well as goblet cell numbers at 72h post LPS. The magnitude of these effects was comparable to that of the positive control dexamethasone (5mg/kg). Conclusion: The herbal medicinal product Bronchipret ® (a fixed combination of thyme and primula dry extract) normalizes pathologically altered determinants of viscous mucus secretion typically accompanying inflammation of the lower respiratory tract. These effects most likely contribute to the clinical efficacy of Bronchipret ® in acute bronchitis.