Green tea polyphenols attenuate deterioration of bone microarchitecture in female rats with systemic chronic inflammation.

UNLABELLED: Green tea polyphenols (GTP) are promising agents for preventing bone loss. GTP supplementation sustained microarchitecture and improved bone quality via a decrease in inflammation. Findings suggest a significant role for GTP in skeletal health of patients with chronic inflammation. INTRODUCTION: This study evaluated whether GTP can restore bone microstructure along with a molecular mechanism in rats with chronic inflammation. A 2 [placebo vs. lipopolysaccharide (LPS)]× 2 [no GTP vs. 0.5% GTP (w/v) in drinking water] factorial design was employed. METHODS: Female rats were assigned to four groups: placebo, LPS, placebo + GTP, and LPS + GTP for 12 weeks. Efficacy was evaluated by examining changes in bone microarchitecture using histomorphometric and microcomputed tomographic analyses and by bone strength using the three-point bending test. A possible mechanism was studied by assessing the difference in tumor necrosis factor-α (TNF-α) expression in tibia using immunohistochemistry. RESULTS: LPS lowered trabecular volume fraction, thickness, and bone formation in proximal tibia while increasing osteoclast number and surface perimeter in proximal tibia and eroded surface in endocortical tibial shafts. GTP increased trabecular volume fraction and number in both femur and tibia and periosteal bone formation rate in tibial shafts while decreasing trabecular separation in proximal tibia and eroded surface in endocortical tibial shafts. There was an interaction between LPS and GTP in trabecular number, separation, bone formation, and osteoclast number in proximal tibia, and trabecular thickness and number in femur. GTP improved the strength of femur, while suppressing TNF-α expression in tibia. CONCLUSION: In conclusion, GTP supplementation mitigated deterioration of bone microarchitecture and improved bone integrity in rats with chronic inflammation by suppressing bone erosion and modulating cancellous and endocortical bone compartments, resulting in a larger net bone volume. Such a protective role of GTP may be due to a suppression of TNF-α.

Synergistic effects of green tea polyphenols and alphacalcidol on chronic inflammation-induced bone loss in female rats.

UNLABELLED: Studies suggest that green tea polyphenols (GTP) or alphacalcidol is promising agent for preventing bone loss. Findings that GTP supplementation plus alphacalcidol administration increased bone mass via a decrease of oxidative stress and inflammation suggest a significant role of GTP plus alphacalcidol in bone health of patients with chronic inflammation. INTRODUCTION: Studies have suggested that green tea polyphenols (GTP) or alphacalcidol are promising dietary supplements for preventing bone loss in women. However, the mechanism(s) related to the possible osteo-protective role of GTP plus D(3) in chronic inflammation-induced bone loss is not well understood. METHODS: This study evaluated bioavailability, efficacy, and related mechanisms of GTP in combination with alphacalcidol in conserving bone loss in rats with chronic inflammation. A 12-week study of 2 (no GTP vs. 0.5% GTP in drinking water) × 2 (no alphacalcidol vs. 0.05 µg/kg alphacalcidol, 5×/week) factorial design in lipopolysaccharide-administered female rats was performed. In addition, a group receiving placebo administration was used to compare with a group receiving lipopolysaccharide administration only to evaluate the effect of lipopolysaccharide. RESULTS: Lipopolysaccharide administration resulted in lower values for bone mass, but higher values for serum tartrate-resistant acid phosphatase (TRAP), urinary 8-hydroxy-2'-deoxyguanosine, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. GTP supplementation increased urinary epigallocatechin and epicatechin concentrations. Both GTP supplementation and alphacalcidol administration resulted in a significant increase in bone mass, but a significant decrease in serum TRAP levels, urinary 8-hydroxydeoxyguanosine levels, and mRNA expression of tumor necrosis factor-α and cyclooxygenase-2 in spleen. A synergistic effect of GTP and alphacalcidol was observed in these parameters. Neither GTP nor alphacalcidol affected femoral bone area or serum osteocalcin. CONCLUSION: We conclude that a bone-protective role of GTP plus alphacalcidol during chronic inflammation bone loss may be due to a reduction of oxidative stress damage and inflammation.