Astragalus membranaceus Inhibits Inflammation via Phospho-P38 Mitogen-Activated Protein Kinase (MAPK) and Nuclear Factor (NF)-κB Pathways in Advanced Glycation End Product-Stimulated Macrophages

Advanced glycation end products (AGEs) and inflammation contribute to the development of diabetic complications. Astragalus membranaceus has properties of immunological regulation in many diseases. The aim of this study was to determine the function of A. membranaceus extract (AME) on the AGE-induced inflammatory response in Ana-1 macrophages. The viability of cells treated with AME or AGEs was evaluated with the MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] method. The secretion and mRNA levels of IL-1β and TNF-α were measured by ELISA and RT-PCR, respectively. The activity of NF-κB was assayed by EMSA. The phosphorylation of p38 MAPK was assessed by western blotting. The results showed that AME was not toxic to macrophages. The treatment of macrophages with AME effectively inhibited AGE-induced IL-1β and TNF-α secretion and mRNA expression in macrophages. These effects may be mediated by p38 MAPK and the NF-κB pathway. The results suggest that AME can inhibit AGE-induced inflammatory cytokine production to down-regulate macrophage-mediated inflammation via p38 MAPK and NF-κB signaling pathways and indicate that AME could be an immunoregulatory agent against AGE-induced inflammation in diabetes.     

The -308G/A of Tumor Necrosis Factor (TNF)-α and 825C/T of Guanidine Nucleotide Binding Protein 3 (GNB3) are Associated with the Onset of Acute Myocardial Infarction and Obesity in Taiwan

Acute myocardial infarction is a highly prevalent cardiovascular disease in Taiwan. Among several etiological risk factors, obesity and inflammation are strongly associated with the frequency of hypertension, cardiovascular disease, diabetes, and myocardial infarction. To discriminate obesity- and inflammation-related genes and the onset of acute myocardial infarction (AMI), a case-control study was conducted to investigate the association of the -308G/A polymorphisms of tumor necrosis factor (TNF)-α and the C825T polymorphism of guanidine nucleotide binding protein 3 (GNB3) with the onset of AMI among Taiwanese cohorts. A total of 103 AMI patients and 163 matched normal control samples were enrolled in the present study. The genomic DNA was extracted and subjected into polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis. An association between the A homozygosity of the TNF-α-308G/A polymorphism and the onset of AMI was observed among the male subjects (p = 0.026; Spearman index = 0.200, p = 0.008). An association between the T homozygosity of GNB3 C825T polymorphism and obesity was also observed (Fisher's exact, p = 0.009). The TT genotype has a protective effect against acquiring AMI among the obese female population in Taiwan (Fisher's exact, p = 0.032). In conclusion, TNF-α-308G/A and the GNB3 C825T polymorphisms are associated with obesity and AMI in the Taiwanese population.     

Fraction from Wax Apple [Syzygium samarangense (Blume) Merrill and Perry] Fruit Extract Ameliorates Insulin Resistance via Modulating Insulin Signaling and Inflammation Pathway in Tumor Necrosis Factor α-Treated FL83B Mouse Hepatocytes

Inflammation is associated with the development of insulin resistance in Type 2 diabetes mellitus. In the present study, mouse FL83B cells were treated with tumor necrosis factor-alpha (TNF-α) to induce insulin resistance, and then co-incubated with a fraction from wax apple fruit extract (FWFE). This fraction significantly increased the uptake of the nonradioactive fluorescent indicator 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) in insulin resistant cells. Western blot analysis revealed that, compared with the TNF-α-treated control group, FWFE increased the expression of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1), protein kinase B (Akt/PKB), phosphatidylinositol-3 kinase (PI3K), and glucose transporter 2 (GLUT-2), and increased IR tyrosyl phosporylation, in insulin resistant FL83B cells. However, FWFE decreased phosphorylation of c-Jun N-terminal kinases (JNK), but not the expression of the intercellular signal-regulated kinases (ERK), in the same cells. These results suggest that FWFE might alleviate insulin resistance in TNF-α-treated FL83B cells by activating PI3K-Akt/PKB signaling and inhibiting inflammatory response via suppression of JNK, rather than ERK, activation.     

Astragalus membranaceus Inhibits Peritoneal Fibrosis via Monocyte Chemoattractant Protein (MCP)-1 and the Transforming Growth Factor-β1 (TGF-β1) Pathway in Rats Submitted to Peritoneal Dialysis

Inflammation and transforming growth factor-β1 (TGF-β1) contribute to the development of peritoneal fibrosis (PF), which is associated with peritoneal dialysis (PD). Astragalus membranaceus (Astragalus) has anti-inflammatory and anti-fibrotic effects in many diseases. The goal of this study was to determine the anti-fibrotic effects of Astragalus on the PF response to PD. A rat model of PD was induced using standard PD fluid, and PF was verified by HE and Masson’s staining, as well as through the expression of fibroblast surface protein (FSP) and collagen III. The expression levels of monocyte chemoattractant protein (MCP)-1, F4/80 (macrophage/monocyte marker in rat), TGF-β1 and the downstream proteins phospho-SMAD 2/3 in dialyzed peritoneal tissue treated with or without Astragalus was evaluated using immunohistochemistry analysis. Overall correlations between MCP-1 and TGF-β1 staining were analyzed using both the Spearman and Pearson methods. The results showed that Astragalus could inhibit the recruitment and activation of monocytes/macrophages, thereby reducing the production of TGF-β1 in the dialyzed peritoneal membrane. PF was also significantly decreased following treatment with Astragalus. MCP-1 expression had a strong positive correlation with TGF-β1 sensitivity, suggesting that the anti-fibrotic function of Astragalus was mediated by MCP-1 and the TGF-β1 pathway. Our results indicate that Astragalus could be a useful agent against PD-induced PF.