Potential effect of one-alpha-hydroxy vitamin D3 (alfacalcidol) on experimentally induced allergic asthma

Abstract

Background: Alfacalcidol is a vitamin D analog mainly used in the management of osteoporosis. Apart from the well-known role of vitamin D in bone and calcium metabolism, an immune-modulator role of vitamin D in allergic diseases was suggested. Aim: To evaluate the potential effect of alfacalcidol either alone or in combination with salbutamol or/and prednisolone and its role in the protection and management of experimentally induced allergic asthma. Materials and methods: Male guinea pigs were divided into two groups: group A constituted normal guinea pigs (received saline) and group B constituted ovalbumin-sensitized guinea pigs, which were divided into eight subgroups: group B1 (control): groups from B2 to B4 was treated with salbutamol, prednisolone, alfacalcidol, respectively, for 1 week, while group B5 was treated with salbutamol+prednisolone; group B6 was treated with salbutamol+alfacalcidol; group B7 was treated with prednisolone+alfacalcidol; and group B8 was treated with salbutamol, prednisolone, and alfacalcidol for 1 week. Twenty-four hours after the last dose, the animals were subjected to both: (a)pharmacological studies, (b) histopathological studies (group A, group B1, B3, and B4). Results: (a) Pharmacological studies: sensitization of guinea pigs caused a significant increase in amplitude of histamine-induced contractions of isolated tracheal smooth muscles in comparison to that of the normal one. Treatment of sensitized guinea pigs with salbutamol, prednisolone, or alfacalcidol produced a significant reduction in the amplitude of histamine-induced contractions in comparison to sensitized nontreated guinea pigs. Addition of alfacalcidol to salbutamol or prednisolone in the treatment of sensitized guinea pigs caused more decrease in the amplitude of histamine-induced contractions. However, the highest reduction in the amplitude of contractions of isolated tracheal strips was produced by the treatment of guinea pigs with a combination of salbutamol, prednisolone, and alfacalcidol. (b) Histopathological examinations: treatment of sensitized guinea pigs with alfacalcidol resulted in an anti-remodeling effect, while prednisolone showed better anti-inflammatory effect, when it was compared with that of the control group. Conclusion: Alfacalcidol was shown to possess anti-inflammatory and anti-remodeling effects in allergic asthma. It was superior to prednisolone regarding the anti-remodeling effect. So, alfacalcidol could be beneficial in the management of allergic asthma.