examined the innate immune pathway in AbdSc AT from lean, obese, and T2DM subjects, and 4) examined the association of circulating LPS in T2DM subjects. The findings showed that LPS increased TLR-2 protein expression twofold (P Ͻ 0.05). Treatment of AbdSc adipocytes with LPS caused a significant increase in TNF-␣ and IL-6 secretion (IL-6, Control: 2.7 Ϯ 0.5 vs. LPS: 4.8 Ϯ 0.3 ng/ml; P Ͻ 0.001; TNF-␣, Control: 1.0 Ϯ 0.83 vs. LPS: 32.8 Ϯ 6.23 pg/ml; P Ͻ 0.001). NF-B inhibitor reduced IL-6 in AbdSc adipocytes (Control: 2.7 Ϯ 0.5 vs. NF-B inhibitor: 2.1 Ϯ 0.4 ng/ml; P Ͻ 0.001). AbdSc AT protein expression for TLR-2, MyD88, TRAF6, and NF-B was increased in T2DM patients (P Ͻ 0.05), and TLR-2, TRAF-6, and NF-B were increased in LPStreated adipocytes (P Ͻ 0.05). Circulating LPS was 76% higher in T2DM subjects compared with matched controls. LPS correlated with insulin in controls (r ϭ 0.678, P Ͻ 0.0001). Rosiglitazone (RSG) significantly reduced both fasting serum insulin levels (reduced by 51%, P ϭ 0.0395) and serum LPS (reduced by 35%, P ϭ 0.0139) in a subgroup of previously untreated T2DM patients. In summary, our results suggest that T2DM is associated with increased endotoxemia, with AT able to initiate an innate immune response. Thus, increased adiposity may increase proinflammatory cytokines and therefore contribute to the pathogenic risk of T2DM.toll-like receptors; adipocytes; nuclear factor-B; inflammation; insulin OBESITY IS KNOWN TO REPRESENT one of the single most important risk factors for the increased risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease. In addition, an increase in central (visceral) adiposity confers higher metabolic risk. This increased metabolic risk is associated with subclinical inflammation, with several studies demonstrating increased levels of proinflammatory adipocytokines, such as IL-6 and TNF-␣ (32, 33), in patients with obesity and T2DM. Activation of proinflammatory adipocytokines in adipose tissue (AT) is coordinated through NF-B, a key transcription factor in the inflammatory cascade (2,10, 11,18,21,22,33,35,37,38). Adipocytes also secrete adiponectin (29,30,36,41,42), which has been shown to possess anti-inflammatory properties through its action on NF-B and is inversely correlated with obesity and diabetes (29,30,36,41,42). Evidence for the role of NF-B in AT has been shown in studies overexpressing the NF-B activator IKK␤ in mice, which resulted in increased inflammatory cytokine production and the onset of diabetes (7). In contrast, hepatocyte IKK␤ knockout (KO) mice demonstrated a decrease in circulating proinflammatory cytokines (3). This indicates that IKK␤ KO mice do not develop hepatic insulin resistance and glucose intolerance compared with their high-fat diet-fed counterparts. Further studies also illustrate that an inflammatory reaction, induced by the bacterial endotoxin lipopolysaccharide (LPS), is markedly attenuated in the IKK␤ KO mice (3

BackgroundEmerging data indicate that gut-derived endotoxin may contribute to low-grade systemic inflammation in insulin resistant states. This study aimed to examine the importance of serum endotoxin and inflammatory markers in non-alcoholic fatty liver disease (NAFLD) patients, with and without type 2 diabetes mellitus (T2DM), and to explore the effect of treatment with a lipase inhibitor, Orlistat, on their inflammatory status.MethodsFasted serum from 155 patients with biopsy proven NAFLD and 23 control subjects were analysed for endotoxin, soluble CD14 (sCD14), soluble tumour necrosis factor receptor II (sTNFRII) and various metabolic parameters. A subgroup of NAFLD patients were re-assessed 6 and 12 months after treatment with diet alone (n = 6) or diet plus Orlistat (n = 8).ResultsEndotoxin levels were significantly higher in patients with NAFLD compared with controls (NAFLD: 10.6(7.8, 14.8) EU/mL; controls: 3.9(3.2, 5.2) EU/mL, p < 0.001); NAFLD alone produced comparable endotoxin levels to T2DM (NAFLD: T2DM: 10.6(5.6, 14.2) EU/mL; non-diabetic: 10.6(8.5, 15.2) EU/mL), whilst a significant correlation between insulin resistance and serum endotoxin was observed (r = 0.27, p = 0.008). Both sCD14 (p < 0.01) and sTNFRII (p < 0.001) increased with severity of fibrosis. A positive correlation was also noted between sTNFRII and sCD14 in the NAFLD subjects (r = 0.29, p = 0.004).Sub-cohort treatment with Orlistat in patients with NAFLD showed significant decreases in ALT (p = 0.006), weight (p = 0.005) and endotoxin (p = 0.004) compared with the NAFLD, non-Orlistat treated control cohort at 6 and 12 months post therapy, respectively.ConclusionsEndotoxin levels were considerably increased in NAFLD patients, with marked increases noted in early stage fibrosis compared with controls. These results suggest elevated endotoxin may serve as an early indicator of potential liver damage, perhaps negating the need for invasive liver biopsy. As endotoxin may promote insulin resistance and inflammation, interventions aimed at reducing endotoxin levels in NAFLD patients may prove beneficial in reducing inflammatory burden.

Introduction: Inflammation contributes to cardiovascular disease and is exacerbated with increased adiposity, particularly omental adiposity; however, the role of epicardial fat is poorly understood.

Resistin is a member of a class of cysteine-rich proteins collectively termed resistin-like molecules. Resistin has been implicated in the pathogenesis of obesity-mediated insulin resistance and T2DM (Type II diabetes mellitus), at least in rodent models. In addition, resistin also appears to be a pro-inflammatory cytokine. Taken together, resistin, like many other adipocytokines, may possess a dual role in contributing to disease risk. However, to date there has been considerable controversy surrounding this 12.5 kDa polypeptide in understanding its physiological relevance in both human and rodent systems. Furthermore, this has led some to question whether resistin represents an important pathogenic factor in the aetiology of T2DM and cardiovascular disease. Although researchers still remain divided as to the role of resistin, this review will place available data on resistin in the context of our current knowledge of the pathogenesis of obesity-mediated diabetes, and discuss key controversies and developments.

Adipose tissue is an active endocrine organ, and our knowledge of this secretory tissue, in recent years, has led us to completely rethink how our body functions and becomes dysregulated with weight gain. Human adipose tissue appears to act as a multifunctional secretory organ with the capacity to control energy homoeostasis through peripheral and central regulation of energy homoeostasis. It also plays an important role in innate immunity. However, the capability to more than double its original mass to cope with positive energy balance in obesity leads to many pathogenic changes. These changes arise within the adipose tissue as well as inducing secondary detrimental effects on other organs like muscle and liver, including chronic low-grade inflammation mediated by adipocytokines (adipokine inflammation). This inflammation is modulated by dietary factors and nutrients including glucose and lipids, as well as gut bacteria in the form of endotoxin or LPS. The aim of this current review is to consider the impact of nutrients such as glucose and lipids on inflammatory pathways, specifically within adipose tissue. Furthermore, how nutrients such as these can influence adipokine inflammation and consequently insulin resistance directly through their effects on secretion of adipocytokines (TNFa, IL6 and resistin) as well as indirectly through increases in endotoxin is discussed.

Aims/hypothesis: It is well established that total systemic adiponectin is reduced in type 2 diabetic subjects. To date most studies have been concerned with the singular full-length protein or proteolytically cleaved globular domain. It is, however, apparent that the native protein circulates in serum as a lower molecular weight hexamer and as larger multimeric structures of high molecular weight (HMW). In this study we address the clinical significance of each form of the protein with respect to glucose tolerance. Methods: Serum was obtained from 34 Indo-Asian male subjects (BMI 26.5±3.1; age 52.15±10.14 years) who had undertaken a 2-h oral glucose tolerance test. An aliquot of serum was fractionated using velocity sedimentation followed by reducing SDS-PAGE. Western blots were probed for adiponectin, and HMW adiponectin as a percentage of total adiponectin (percentage of higher molecular weight adiponectin [S A ] index) was calculated from densitometry readings. Total adiponectin was measured using ELISA; leptin, insulin and IL-6 were determined using ELISA. Results: Analysis of the cohort demonstrated that total adiponectin (r=0.625, p=0.0001), fasting insulin (r=−0.354, p=0.040) and age (r=0.567, p=0.0001) correlated with S A . S A showed a tighter, inverse correlation with 2-h glucose levels (r=−0.58, p=0.0003) than total adiponectin (r=−0.38, p=0.0001). Conclusions/interpretation: This study demonstrates the importance of the S A index as a better determinant of glucose intolerance than measurements of total adiponectin. Our findings suggest that HMW adiponectin is the active form of the protein.

OBJECTIVETo evaluate the changes in circulating endotoxin after a high–saturated fat meal to determine whether these effects depend on metabolic disease state.RESEARCH DESIGN AND METHODSSubjects (n = 54) were given a high-fat meal (75 g fat, 5 g carbohydrate, 6 g protein) after an overnight fast (nonobese control [NOC]: age 39.9 ± 11.8 years [mean ± SD], BMI 24.9 ± 3.2 kg/m2, n = 9; obese: age 43.8 ± 9.5 years, BMI 33.3 ± 2.5 kg/m2, n = 15; impaired glucose tolerance [IGT]: age 41.7 ± 11.3 years, BMI 32.0 ± 4.5 kg/m2, n = 12; type 2 diabetic: age 45.4 ± 10.1 years, BMI 30.3 ± 4.5 kg/m2, n = 18). Blood was collected before (0 h) and after the meal (1–4 h) for analysis.RESULTSBaseline endotoxin was significantly higher in the type 2 diabetic and IGT subjects than in NOC subjects, with baseline circulating endotoxin levels 60.6% higher in type 2 diabetic subjects than in NOC subjects (P < 0.05). Ingestion of a high-fat meal led to a significant rise in endotoxin levels in type 2 diabetic, IGT, and obese subjects over the 4-h time period (P < 0.05). These findings also showed that, at 4 h after a meal, type 2 diabetic subjects had higher circulating endotoxin levels (125.4%↑) than NOC subjects (P < 0.05).CONCLUSIONSThese studies have highlighted that exposure to a high-fat meal elevates circulating endotoxin irrespective of metabolic state, as early as 1 h after a meal. However, this increase is substantial in IGT and type 2 diabetic subjects, suggesting that metabolic endotoxinemia is exacerbated after high fat intake. In conclusion, our data suggest that, in a compromised metabolic state such as type 2 diabetes, a continual snacking routine will cumulatively promote their condition more rapidly than in other individuals because of the greater exposure to endotoxin.

Aims/hypothesis Adiponectin is an adipocyte-derived secretory factor that is specifically produced in adipocytes. It exerts effects on energy homeostasis via peripheral and central mechanisms. However, it is not clear whether adiponectin crosses the blood-brain barrier in humans. In serum, adiponectin circulates in several different complexes, each of which has distinct functions. Here, we wanted to test whether adiponectin can be found in human cerebrospinal fluid (CSF) and whether specific adiponectin complexes are enriched in CSF compared with peripheral serum samples. We also wanted to establish whether there is a sex-related difference with regard to the distribution of adiponectin oligomers in CSF. Materials and methods We studied 22 subjects (11 men, 11 women) in this study. Their average BMI was 28.0± 4.7 kg/m 2 ; average age was 70±7 years. Results Analysis of total adiponectin revealed that adiponectin protein is present in human CSF at approximately 0.1% of serum concentration. The distribution of adiponectin oligomers differs considerably in CSF from that of serum within matched samples from the same patients. Only the adiponectin trimeric and low-molecular-mass hexameric complexes are found in CSF, with a bias towards the trimeric form in most patients. Male subjects have a higher CSF: serum ratio of total adiponectin (p<0.05; n=20) and have slightly higher trimer levels in serum and CSF than female subjects. Conclusions/interpretation We conclude that the adiponectin trimer is the predominant oligomer in human CSF.