Over 200 million people suffer from osteoporosis worldwide. Individuals with osteoporosis have increased rates of bone resorption while simultaneously having impaired osteogenesis. Most current treatments for osteoporosis focus on anti-resorptive methods to prevent further bone loss. However, it is important to identify safe and cost-efficient treatments that not only inhibit bone resorption, but also stimulate anabolic mechanisms to upregulate osteogenesis. Recent data suggest that macrophage polarization may contribute to osteoblast differentiation and increased osteogenesis as well as bone mineralization. Macrophages exist in two major polarization states, classically activated macrophages (M1) and alternatively activated macrophage (M2) macrophages. The polarization state of macrophages is dependent on molecules in the microenvironment including several cytokines and chemokines. Mechanistically, M2 macrophages secrete osteogenic factors that stimulate the differentiation and activation of pre-osteoblastic cells, such as mesenchymal stem cells (MSC’s), and subsequently increase bone mineralization. In this review, we cover the mechanisms by which M2 macrophages contribute to osteogenesis and postulate the hypothesis that regulating macrophage polarization states may be a potential treatment for the treatment of osteoporosis.
Oxidative stress and inflammation are central to the development of a number of chronic diseases including cardiovascular disease and previous research suggests that blueberry consumption may attenuate these processes. The present study investigated the effects of blueberries on blood biomarkers of oxidative stress, inflammation, and antioxidant defense in postmenopausal women with pre- and stage 1-hypertension. In a randomized, parallel-arm, double-blind, placebo-controlled clinical trial, 40 pre- and stage 1-hypertensive postmenopausal women aged 45 to 65 years were randomly assigned to receive 22 g freeze-dried highbush blueberry powder per day (Blueberry) or 22 g placebo powder per day (Control) for 8 weeks. A blood biomarker of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (8-OHdG), as well as blood biomarkers of oxidative stress, inflammation, and antioxidant defense were assessed at baseline, 4 and 8 weeks. 8-OHdG levels were significantly (P = 0.008) lower in Blueberry compared to Control at 4 weeks with a significant time-by-treatment interaction (P = 0.04). Levels were not different between groups at 8 weeks. Other biomarkers measured were not affected by blueberry consumption. Daily consumption of blueberries for 4 weeks, but not 8 weeks, attenuated a biomarker of oxidative DNA damage in pre- and stage 1-hypertensive postmenopausal women. Future clinical studies should directly evaluate the effects of blueberry consumption on oxidative stress, inflammation, and antioxidant defense at the cellular level and in the vasculature in this population.
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