RESUMO
BACKGROUND: Atherosclerosis and inflammation are more common in patients with diabetes than in patients without diabetes, and atherosclerosis progression contributes to inflammation. Therefore, anti-inflammatory therapy is important for the prognosis of patients with diabetes. Linagliptin is the only bile-excreted, anti-diabetic oral dipeptidyl peptidase-4 (DPP-4) inhibitor. Although the anti-inflammatory effects of DPP-4 inhibitors in vivo and in vitro have been reported, few in vitro studies have examined the effects of linagliptin using monocytes, which play a central role in arteriosclerosis-related inflammation. Herein, we assessed the anti-inflammatory effects of linagliptin in human U937 monocytes. METHODS: U937 cells at densities of 1 × 106 cells/mL were cultured in Roswell Park Memorial Institute medium supplied with 10% fetal bovine serum and treated with 100 nM phorbol myristate acetate for 48 h for differentiation into macrophages. The media were replaced, and the cells were pretreated with 1, 5, 10, 50, and 100 nM linagliptin for 1 h or were left untreated. The media were then replaced again, and the cells were treated with 1 µg/mL lipopolysaccharide (LPS) or 10 nM interleukin (IL)-1ß only, in combination with 1, 5, 10, 50, and 100 nM linagliptin or were left untreated. The extracted media were used to measure IL-6 and tumor necrosis factor (TNF)-α levels using enzyme-linked immunosorbent assay kits. RESULTS: LPS alone significantly increased IL-6 and TNF-α production compared with the control treatment. The treatment of cells with linagliptin at all concentrations significantly inhibited the LPS-stimulated IL-6 and TNF-α production. Meanwhile, IL-1ß alone significantly increased IL-6 production compared with the control treatment. No significant difference in IL-6 production was noted between the cells treated with IL-1ß and simultaneous treatment with IL-1ß and linagliptin. CONCLUSIONS: Linagliptin inhibited LPS-induced inflammation in human monocytic U937 cells.
RESUMO
BACKGROUND: Because of the potential anti-inflammatory effects, linagliptin, a therapeutic dipeptidyl peptidase-4 inhibitor, is used as an effective drug for diabetic patients for whom inflammation is a prognosis-related factor. We investigated the anti-inflammatory mechanism of linagliptin using seven markers. METHODS: We pretreated human umbilical vein endothelial cells (HUVECs), with linagliptin and lipopolysaccharide (LPS). The cytosolic fractions were evaluated for protein kinase A (PKA), protein kinase B (PKB), protein kinase C (PKC), ratio of reactive oxygen species (ROS) and Cu/Zn superoxide dismutase (SOD), activator protein 1 (AP-1), and adenosine 3',5'-cyclic monophosphate (cAMP). RESULTS: Linagliptin increased the PKA and PKC activities and the cAMP levels in LPS-treated cells. However, it inhibited LPS-induced PKB phosphorylation, ratio of ROS and Cu/Zn SOD, and LPS-stimulated AP-1 nuclear translocation. CONCLUSION: We reaffirmed the anti-inflammatory and antioxidant effects of linagliptin. These effects might be related to the three protein kinases. Our findings suggest that linagliptin has a wide range of anti-inflammatory effects.
RESUMO
Novel phenethyl ether derivatives (PhE) and cinnamic amide derivatives (CA), which have two mono- or polyphenol rings connected either by an ether (PhE) or amide bond (CA), were synthesized. We investigated their ability to scavenge the O2- and DPPH radicals in vitro, using ESR spectroscopy, in relation to their cytotoxic activity against a human oral squamous cell carcinoma (HSC-2) cell line. The radical scavenging activity was considerably influenced by the position of the hydroxyl groups in the benzene rings. Based on their radical scavenging activity and cytotoxicity, these compounds were classified into two groups: active compounds (such as catechol and hydroquinone) and inactive compounds (such as resorcin and phenol). These results suggest a close relationship between the cytotoxic activity and radical scavenging activity derived from ortho-para preference in dihydroxybenzene. PhE and CA might show potential activity in free radical mediated diseases.
