Eosinophil recruitment to the airways is a characteristic feature of allergic asthma. Eotaxins are potent chemokines that regulate the recruitment of eosinophils to sites of inflammation. Of these, CCL26 is linked to persistent eosinophil recruitment in the later phase of an allergic response. We evaluated the effectiveness of 10 different blackcurrant cultivar polyphenolic extracts in suppressing CCL26 secretion in stimulated human alveolar epithelial cells. Correlation analysis to identify the potential blackcurrant composition constituent(s) involved in CCL26 suppression and the effects of the four major anthocyanins present in blackcurrants to validate results was conducted. All blackcurrant polyphenolic extracts suppressed CCL26 secretion by lung alveolar cells; however, differential efficacy was observed, which was attributed to their cultivar-specific polyphenolic composition profiles. We identified that the ratio of concentrations of delphinidin glycosides to cyanidin glycosides in the blackcurrant cultivars was an important determinant in influencing CCL26 suppression in lung cells. Our findings support the potential use of blackcurrants or blackcurrant-derived foods/ingredients in managing lung inflammation and the development of specific cultivars as functional foods/ingredients with beneficial biological activities.

Asthma is an allergy-mediated inflammatory disease characterised by infiltration of the airway with mast cells, lymphocytes, and eosinophils. The disease is induced by co-ordination of T-helper cell type 2 (Th2) cytokines and inflammatory signal molecules. Fruits and vegetables are a rich source of polyphenolic bioactive compounds, which have been observed to have health-promoting properties when consumed by humans. In particular, fruit-derived proanthocyanins and anthocyanins have been found to attenuate lung inflammation. Epidemiological studies have revealed correlations between fruit consumption and a lower prevalence of respiratory symptoms and lower incidence of non-specific lung diseases. In this review we summarise the current understanding of the pathophysiologic mechanism(s) involved in the development of allergic airway disease. We also review evidence of the beneficial effects of plant-derived foods, their components and metabolites in allergic airway inflammation arising from in vitro and rodent studies, epidemiological studies and human intervention trials. The mechanism, biological relevance and functional benefits, such as immune modulation (e.g. reduction in cytokine and eotaxin production), antioxidant ability, tissue remodelling and tight junction function are also discussed.