OBJECTIVETo study the relationship between the expression of serum amyloid A (SAA) and insulin resistance in 3T3-L1 adipocytes.

METHODS3T3-L1 adipocytes were incubated with different concentrations of dexamethasone (10, 100, and 1000 nmol/L) for 48 h to establish cell models of insulin resistance at different resistant levels (models 1, 2, and 3, respectively). The degree of insulin resistance of 3T3-L1 adipocytes was assayed by 2-deoxy-[(3)H]-D-glucose uptake. Semi- quantitative RT-PCR was performed for quantification of SAA mRNA expression. SAA concentrations in the culture medium were determined by ELISA.

RESULTDexamethasone did not affect the basal glucose transport (P>0.05). Insulin-stimulated glucose uptake was significantly decreased by 15% (P<0.05), 40% (P<0.01), and 55% (P<0.01) in models 1, 2, and 3 in comparison with the untreated group, respectively; the expressions of SAA mRNA were upregulated by 2.5 (P<0.01), 3.33 (P<0.01), and 4.08 folds (P<0.01) and SAA concentrations increased by 2.05, 3.13, and 4.23 folds, respectively. The expressions of SAA mRNA were positively correlated to the degree of insulin resistance (r=0.773, P<0.01) and SAA concentration (r=0.832, P<0.01).

CONCLUSIONA cell model of insulin resistance has been established in 3T3-L1 adipocytes by dexamethasone exposure. SAA is closely associated with insulin resistance and may serve as a marker of insulin resistance.

3T3-L1 Cells ; Adipocytes ; metabolism ; Animals ; Deoxyglucose ; metabolism ; Dexamethasone ; pharmacology ; Enzyme-Linked Immunosorbent Assay ; Insulin Resistance ; Mice ; RNA, Messenger ; genetics ; metabolism ; Serum Amyloid A Protein ; genetics ; metabolism

In this study, we observed that lysophosphatidylglycerol (LPG) completely inhibited a formyl peptide receptor like-1 (FPRL1) agonist (MMK-1)-stimulated chemotactic migration in human phagocytes, such as neutrophils and monocytes. LPG also dramatically inhibited IL-1beta production by another FPRL1 agonist serum amyloid A (SAA) in human phagocytes. However, LPG itself induced intracellular calcium increase and superoxide anion production in human phagocytes. Keeping in mind that phagocytes migration and IL-1beta production by FPRL1 are important for the induction of inflammatory response, our data suggest that LPG can be regarded as a useful material for the modulation of inflammatory response induced by FPRL1 activation.
Chemotaxis, Leukocyte/*drug effects ; Humans ; Interleukin-1beta/*biosynthesis ; Lysophospholipids/*pharmacology ; Monocytes/drug effects/immunology/metabolism/physiology ; Neutrophils/drug effects/immunology/metabolism/physiology ; Peptides/metabolism/pharmacology ; *Phagocytes/drug effects/immunology/metabolism/physiology ; Receptors, Formyl Peptide/*metabolism ; Receptors, Lipoxin/*metabolism ; Serum Amyloid A Protein/metabolism/pharmacology

BACKGROUNDA five-year follow-up study of intensive multifactorial intervention was undertaken to assess the changes of circulating serum amyloid A (SAA) levels and the incidence of atherosclerosis (AS) in patients with short-duration type 2 diabetes mellitus (T2DM) without macroangiopathy, and whether intensive multifactorial intervention could prevent or at least postpone the occurrence of macroangiopathy.

METHODSAmong 150 patients with short-duration T2DM, 75 were assigned to receive conventional outpatient treatment (conventional group) and the others underwent intensive multifactorial integrated therapy targeting hyperglycemia, hypertension, dyslipidemia and received aspirin simultaneously (intensive group).

RESULTSPlasma SAA levels were higher in diabetic patients than those in healthy control subjects, and decreased obviously after intensive multifactorial intervention. The levels of SAA were positively correlated with body mass index (BMI), waist hip ratio (WHR), triglyceride (TG), high sensitive C-reactive protein (hs-CRP) and common carotid intima-media thickness (CC-IMT). The standard-reaching rates of glycemia, blood pressure and lipidemia were significantly higher in intensive group than those of conventional group. The incidence of macroangiopathy decreased by 58.96% in intensive group compared with conventional group.

CONCLUSIONSIntensive multifactorial intervention may significantly reduce the SAA levels and prevent the occurrence of AS in short-duration patients with T2DM. SAA might be one of the risk factors of T2DM combined with AS.

Adult ; Aged ; Antihypertensive Agents ; pharmacology ; therapeutic use ; Blood Glucose ; metabolism ; C-Reactive Protein ; metabolism ; Diabetes Mellitus, Type 2 ; complications ; drug therapy ; metabolism ; Diabetic Angiopathies ; etiology ; Female ; Humans ; Hypoglycemic Agents ; pharmacology ; therapeutic use ; Hypolipidemic Agents ; pharmacology ; therapeutic use ; Male ; Middle Aged ; Multivariate Analysis ; Serum Amyloid A Protein ; metabolism ; Triglycerides ; blood ; Tunica Media ; drug effects

Serum amyloid A (SAA) has been regarded as an important mediator of inflammatory responses. The effect of several formyl peptide receptor-like 1 (FPRL1) ligands on the production of IL-8 by SAA was investigated in human neutrophils. Among the ligands tested, LL-37 was found to specifically inhibit SAA-induced IL-8 production in transcriptional and post-transcriptional levels. Since SAA stimulated IL-8 production via ERK and p38 MAPK in human neutrophils, we tested the effect of LL-37 on SAA induction for these two MAPKs. LL-37 caused a dramatic inhibition of ERK and p38 MAPK activity, which is induced by SAA. LL-37 was also found to inhibit SAA-stimulated neutrophil chemotactic migration. Further, the LL-37-induced inhibitory effect was mediated by FPRL1. Our findings indicate that LL-37 is expected to be useful in the inhibition of SAA signaling and for the development of drugs against SAA-related inflammatory diseases.
Animals ; Antimicrobial Cationic Peptides/*pharmacology ; Cell Line, Tumor ; Cell Movement ; Chemotaxis, Leukocyte ; Humans ; Interleukin-8/*biosynthesis ; MAP Kinase Kinase Kinases/metabolism ; Neutrophils/drug effects/*immunology ; Proto-Oncogene Proteins/metabolism ; Rats ; Receptors, Formyl Peptide/metabolism ; Receptors, Lipoxin/metabolism ; Serum Amyloid A Protein/*antagonists & inhibitors ; Signal Transduction ; Transcription, Genetic

Serum amyloid A (SAA) has been regarded as an important mediator of inflammatory responses. The effect of several formyl peptide receptor-like 1 (FPRL1) ligands on the production of IL-8 by SAA was investigated in human neutrophils. Among the ligands tested, LL-37 was found to specifically inhibit SAA-induced IL-8 production in transcriptional and post-transcriptional levels. Since SAA stimulated IL-8 production via ERK and p38 MAPK in human neutrophils, we tested the effect of LL-37 on SAA induction for these two MAPKs. LL-37 caused a dramatic inhibition of ERK and p38 MAPK activity, which is induced by SAA. LL-37 was also found to inhibit SAA-stimulated neutrophil chemotactic migration. Further, the LL-37-induced inhibitory effect was mediated by FPRL1. Our findings indicate that LL-37 is expected to be useful in the inhibition of SAA signaling and for the development of drugs against SAA-related inflammatory diseases.
Animals ; Antimicrobial Cationic Peptides/*pharmacology ; Cell Line, Tumor ; Cell Movement ; Chemotaxis, Leukocyte ; Humans ; Interleukin-8/*biosynthesis ; MAP Kinase Kinase Kinases/metabolism ; Neutrophils/drug effects/*immunology ; Proto-Oncogene Proteins/metabolism ; Rats ; Receptors, Formyl Peptide/metabolism ; Receptors, Lipoxin/metabolism ; Serum Amyloid A Protein/*antagonists & inhibitors ; Signal Transduction ; Transcription, Genetic

PURPOSE: To investigate the production of long pentraxin 3 (PTX3) in response to tunicamycin-induced endoplasmic reticulum (ER) stress and its role in ER stress-associated cell death, PTX3 expression was evaluated in the human retinal pigment epithelial cell line, ARPE-19. METHODS: PTX3 production in ARPE-19 cells was analyzed in the absence or presence of tunicamycin treatment by enzyme-linked immunosorbent assay. PTX3 protein and mRNA levels were estimated using western blot analysis and real-time reverse transcription-polymerase chain reaction, respectively. Protein and mRNA levels of CCAAT-enhancer-binding protein homologous protein (CHOP) and ARPE-19 cell viability were measured in the presence of tunicamycin-induced ER stress in control or PTX3 small hairpin RNA (shRNA)-transfected ARPE-19 cells. RESULTS: The protein and mRNA levels of PTX3 were found to be significantly increased by tunicamycin treatment. PTX3 production was significantly decreased in inositol-requiring enzyme 1α shRNA-transfected ARPE-19 cells compared to control shRNA-transfected cells. Furthermore, pretreatment with the NF-κB inhibitor abolished tunicamycin-induced PTX3 production. Decreased cell viability and prolonged protein and mRNA expression of CHOP were observed under tunicamycin-induced ER stress in PTX3 shRNA transfected ARPE-19 cells. CONCLUSIONS: These results suggest that PTX3 production increased in the presence of tunicamycin-induced ER stress. Therefore, PTX3 could be an important protector of ER stress-induced cell death in human retinal pigment epithelial cells. Inositol-requiring enzyme 1α and the NF-κB signaling pathway may serve as potential targets for regulation of PTX3 expression in the retina. Therefore, their role in PTX3 expression needs to be further investigated.
Anti-Bacterial Agents/pharmacology ; Apoptosis ; Blotting, Western ; C-Reactive Protein/biosynthesis/*genetics ; Cells, Cultured ; Endoplasmic Reticulum Stress/*drug effects/genetics ; Enzyme-Linked Immunosorbent Assay ; *Gene Expression Regulation ; Humans ; Polymerase Chain Reaction ; RNA, Messenger/*genetics ; Retinal Pigment Epithelium/*metabolism/pathology ; Serum Amyloid P-Component/biosynthesis/*genetics ; Tunicamycin/*pharmacology