Some studies have demonstrated that apple polyphenols have a protective effect against diseases as chronic obstructive pulmunary disease involving a wide variety of cells and inflammatory mediators. The most important etiologic factor is cigarette smoke. It contains ROS, such as superoxide anion, hidroxil radical and hydrogen peroxide. It can induce barrier dysfunction of lung epithelial cells, immune dysregulation, an imbalance of proinflammatory cytokines leading to tissue injury. That is associated to an influx of neutrophilis and macrophages. Macrophage-delivered matrix metalloproteinases MMP-9 can attack the alveolar wall directly, leading to both matrix destruction and liberation of elastin fragments and further amplifying the inflammatory response. Evidence suggests that smoke causes a decease in endogenous antioxidant activity, including decreased levels of GSH and SOD activity.
Polyphenols exert a protective effect by decreasing oxidative damage to cells. They inhibit basal and cytokine-stimulated release of IL-8 and granulocyte-macrophage colony stimulating factor by macrophages. Administration of polyphenols damps the expression of proinflammatory transcripts, such as IL-1b, TNFa, CXCL1 and MPC1.
Activation and infiltration of immune cells including macrophages and neutrophilis plays an important role in the expression of various proinflammatory cytokines and chemokines .
Cigarette smoke contains multiple oxidative moieties. These ROS have the ability to damage lipids, proteins, DNA and the extracellular matrix. Polyphenols may have relevance to regulate the imbalance between oxidants and antioxidants, which is proposed in COPD.
The effects of polyphenols come out in the regulation of MMP-9 expression.
MMP-9 is a key enzyme involved in the degradation of the extracellular matrix components during normal remodelling and repair processes. After smoke exposure the levels of MMP-9 are high; polyphenols significantly prevent the up-regulated protein expression.
Exposure of cells to a variety of oxidative stresses induces activation of multiple MAPK pathways, including P38 MAPK. These signal trasduction pathways are also known to regulate the expressionf of proinflammatory cytokines. Polyphenols inhibit the activation of P38 MAPK and the increased expression in the lungs.
For that evidences polyphenols not only reduce the cigarette smoke-induced accumulation and infiltration of inflammatory cells, but also reverse all oxidative/antioxidant markers, including decreased SOD activity and GSH levels. Moreover they reduce the cigarette smoke metalloproteinases expression in the lungs.
The experiment provides that the necessary concentration of polyphenols for giving a protective effect is around 300mg, that corresponds to 1 or 2 apples for day, so it is possible that the proverb "An apple a day keeps the doctor away" is correct!
Apple Polyphenol protects against cigarette smoke lung acute injury.2012
Apple phytochemicals and they health benefits.2004