Suppression of colonic oxidative stress caused by chronic ethanol administration and attenuation of ethanol-induced colitis and gut leakiness by oral administration of sesaminol in mice.

Chronic consumption of excess ethanol is one of the major risk factors for colorectal cancer (CRC), and the pathogenesis of ethanol-related CRC (ER-CRC) involves ethanol-induced oxidative-stress and inflammation in the colon and rectum, as well as gut leakiness. In this study, we hypothesised that oral administration of sesaminol, a sesame lignan, lowers the risk of ER-CRC because we found that it is a strong antioxidant with very low prooxidant activity. This hypothesis was examined using a mouse model, in which 2.0% v/v ethanol was administered ad libitum for 2 weeks with or without oral gavage with sesaminol (2.5 mg per day). Oral sesaminol administration suppressed the ethanol-induced colonic lesions and the ethanol-induced elevation of the colonic levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine, malondialdehyde, and 4-hydroxyalkenals). It consistently suppressed the chronic ethanol-induced expressions of cytochrome P450-2E1 and inducible nitric oxide synthase and upregulated heme oxygenase-1 expression, probably via the nuclear factor erythroid-derived 2-like 2 pathway in the mouse colon. Oral sesaminol administration also suppressed the chronic ethanol-induced elevation of colonic inflammation marker levels, such as those of tumour necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1, probably via the nuclear factor-kappa B pathway. Moreover, it prevented the chronic ethanol-induced gut leakiness by restoring tight junction proteins, giving rise to lower plasma endotoxin levels compared with those of ethanol-administered mice. All of these results suggest that dietary supplementation of sesaminol may lower the risk of ER-CRC by suppressing each of the above-mentioned steps in ER-CRC pathogenesis.

Association between urinary N-acetyl-ß-glucosaminidase activity-urinary creatinine concentration ratio and risk of disability and all-cause mortality.

BACKGROUND: Recent studies have suggested that chronic kidney disease is associated with cardiovascular disease, dementia, and frailty, all of which cause disability and early death. We investigated whether increased activity of urinary N-acetyl-ß-glucosaminidase (NAG), a marker of kidney injury, is associated with risk of disability or all-cause mortality in a general population. METHODS: Follow-up data from the Hidaka Cohort Study, a population-based cohort study of members of a Japanese rural community, were obtained via questionnaires completed by participants or their relatives. Multivariable analyses were used to investigate relations between urinary NAG activity-urinary creatinine concentration ratio and risk of disability or all-cause mortality. RESULTS: A total of 1182 participants were followed up for a median of 12.4 years. The endpoints were receipt of support under the public long-term care insurance program, and all-cause mortality. A total of 122 participants (10.3%) were reported to be receiving long-term care and 230 (19.5%) had died. After adjustment for cardiovascular risk factors along with physical activity, and using the quartile 1 results as a reference, the odds ratio (OR) for disability was 2.12 [95% confidence interval (95% confidence interval [CI]), 1.04-4.33; p = 0.038) and the hazard ratio (HR) for all-cause mortality was 1.65 (95% CI, 1.05-2.62; p = 0.031) in participants with urinary NAG/creatinine ratio in quartile 4. Similar results were obtained in participants without proteinuria: OR for disability, 2.46 (95% CI, 1.18-5.16; p = 0.017); and HR for all-cause mortality, 1.62 (95% CI, 1.00-2.63; p = 0.049). CONCLUSIONS: Increased urinary NAG/creatinine ratio was associated with risk of disability or all-cause mortality in a general population.

Alteration of oxidative-stress and related marker levels in mouse colonic tissues and fecal microbiota structures with chronic ethanol administration: Implications for the pathogenesis of ethanol-related colorectal cancer.

Chronic ethanol consumption is a risk factor for colorectal cancer, and ethanol-induced reactive oxygen species have been suggested to play important roles in the pathogenesis of ethanol-related colorectal cancer (ER-CRC). In this study, the effects of 10-week chronic administration of ethanol on the colonic levels of oxidative stress and advance glycation end product (AGE) levels, as well as fecal microbiota structures, were examined in a mouse model. Chronic oral administration of ethanol in mice (1.0 mL of 1.5% or 5.0% ethanol (v/v) per day per mouse, up to 10 weeks) resulted in the elevation of colonic levels of oxidative stress markers (such as 8-hydroxy-2'-deoxyguanosine and 4-hydroxynonenal) compared to control mice, and this was consistently accompanied by elevated levels of inflammation-associated cytokines and immune cells (Th17 and macrophages) and a decreased level of regulatory T (Treg) cells to produce colonic lesions. It also resulted in an alteration of mouse fecal microbiota structures, reminiscent of the alterations observed in human inflammatory bowel disease, and this appeared to be consistent with the proposed sustained generation of oxidative stress in the colonic environment during chronic ethanol consumption. Moreover, the first experimental evidence that chronic ethanol administration results in elevated levels of advanced glycation end products (AGEs) and their receptors (RAGE) in the colonic tissues in mice is also shown, implying enhanced RAGE-mediated signaling with chronic ethanol administration. The RAGE-mediated signaling pathway has thus far been implicated as a link between the accumulation of AGEs and the development of many types of chronic colitis and cancers. Thus, enhancement of this pathway likely exacerbates the ethanol-induced inflammatory states of colonic tissues and might at least partly contribute to the pathogenesis of ER-CRC.

Impact of serum cholesterol esterification rates on the development of diabetes mellitus in a general population.

BACKGROUND: Lecithin:cholesterol acyltransferase (LCAT) plays an important role in cholesterol esterification in serum. Serum LCAT activity is elevated in patients with serum high triglyceride and low high-density lipoprotein-cholesterol (HDL-C) concentrations, both of which are related to metabolic syndrome and subsequent diabetes mellitus, referred to as lipotoxicity. We hypothesized that increased serum LCAT activity could predict future risk of diabetes mellitus in a general Japanese population. METHODS: We prospectively studied 1496 individuals aged 20-86 years without histories of diabetes mellitus at baseline. Serum lipid concentrations, glucose parameters, and LCAT activity measured as the serum cholesterol esterification rate, were evaluated. RESULTS: During 11 years of follow-up, 46 newly diagnosed patients with diabetes mellitus were reported. After adjustment for plasma glycosylated hemoglobin A1c (HbA1c) levels, the relative risks (RRs) for the development of diabetes mellitus were 5.45 [95% confidence interval (95% CI) 2.37-12.55; P <  0.001] for body-mass index, 0.22 (95% CI, 0.09-0.53; P = 0.001) for HDL-C, 4.81 (95% CI, 1.96-11.77; P = 0.001) for triglyceride, and 4.64 (95% CI, 1.89-11.41; P = 0.001) for LCAT activity. After adjustment for HbA1c, total cholesterol, triglyceride, HDL-C, phospholipid, and free fatty acid levels, the RR of LCAT activity for future risk of diabetes mellitus remained significant (RR, 4.93; 95% CI,1.32-18.41; P = 0.018). In this analysis, we found a significant association between LCAT activity and risk of diabetes mellitus in men but not in women. CONCLUSION: Increased serum cholesterol esterification rate is a potent predictor for future diabetes mellitus.

Are Short Chain Fatty Acids in Gut Microbiota Defensive Players for Inflammation and Atherosclerosis?

Intestinal flora (microbiota) have recently attracted attention among lipid and carbohydrate metabolism researchers. Microbiota metabolize resistant starches and dietary fibers through fermentation and decomposition, and provide short chain fatty acids (SCFAs) to the host. The major SCFAs acetates, propionate and butyrate, have different production ratios and physiological activities. Several receptors for SCFAs have been identified as the G-protein coupled receptor 41/free fatty acid receptor 3 (GPR41/FFAR3), GPR43/FFAR2, GPR109A, and olfactory receptor 78, which are present in intestinal epithelial cells, immune cells, and adipocytes, despite their expression levels differing between tissues and cell types. Many studies have indicated that SCFAs exhibit a wide range of functions from immune regulation to metabolism in a variety of tissues and organs, and therefore have both a direct and indirect influence on our bodies. This review will focus on SCFAs, especially butyrate, and their effects on various inflammatory mechanisms including atherosclerosis. In the future, SCFAs may provide new insights into understanding the pathophysiology of chronic inflammation, metabolic disorders, and atherosclerosis, and we can expect the development of novel therapeutic strategies for these diseases.

Butyrate attenuates lipolysis in adipocytes co-cultured with macrophages through non-prostaglandin E2-mediated and prostaglandin E2-mediated pathways.

BACKGROUND: Interactions between adipocytes and macrophages are associated with metabolic disorders. Production of pro-inflammatory mediators and the release of free fatty acids (FFAs) increase when these cells are co-cultured; butyrate significantly diminishes these effects by suppressing both the macrophage inflammatory and adipocyte lipolysis pathways. Butyrate is known to up-regulate the expression of prostaglandin E2 (PGE2). Therefore, we hypothesized that PGE2 is associated with the suppression of lipolysis by butyrate in co-culture. METHODS: Using contact or transwell co-culture methods with differentiated 3T3-L1 adipocytes and RAW264.7 macrophages, we investigated the effects of butyrate on the release of PGE2 into the medium and on lipolysis in adipocytes. To elucidate the underlying mechanism, we examined the effects of butyrate on cyclooxygenase-2 (COX2) and phospholipase A2 (PLA2) in co-cultured cells, and cyclic adenine monophosphate (cAMP) and protein kinase A type 1-α regulatory subunit (PRKAR1A) in co-cultured adipocytes. Silent interfering (si)RNA targeting of G-protein-coupled receptor (GPR)41 and 109A was employed to examine the effect on lipolysis in TNF-α-stimulated adipocytes. RESULTS: Co-culture increased PGE2 release into the medium, compared with cells cultured separately. Butyrate significantly increased PGE2 production. Co-culture elevated COX2 expression in macrophages and adipocytes, and butyrate further enhanced this effect. Co-culture enhanced cytosolic PLA2 activity in macrophages, which was further enhanced by butyrate. As for lipolysis, co-culture increased the release of FFAs and free glycerol into the medium, whereas butyrate (and to a lesser extent, PGE2) suppressed FFAs and free glycerol release. An inhibition study using a prostaglandin E receptor 3-selective antagonist suggested that approximately 40% of the suppressive effect of butyrate depends on the PGE2-mediated pathway, whereas 60% depends on a non-PGE2-mediated pathway. Co-culture increased cAMP and PRKAR1A levels in adipocytes, whereas butyrate restored the levels to those of the control. Similarly, in TNF-α-stimulated adipocytes, butyrate reduced FFAs and free glycerol release. siRNA inhibition of GPR41 and GPR109A suggested that the GPR109A-mediated pathway predominates, but the GPR41-mediated pathway also regulates the effect of butyrate on lipolysis in TNF-α-stimulated 3T3-L1 cells. CONCLUSIONS: Butyrate attenuates lipolysis in adipocytes co-cultured with macrophages via non-PGE2-mediated and PGE2-mediated pathways.

[Nutrition and atherosclerotic cardiovascular disease].

Atherosclerotic lesion called atheroma includes large amounts of cholesterol. Intake of cholesterol and quality of free fatty acids contributes to the increase of serum cholesterol level and the development of atherosclerosis. A high level of low-density lipoprotein cholesterol is established as a the most dangerous risk factor to promote atherosclerosis. However, recent dietary instruction is focusing on the diet pattern instead of the dietary individual nutrients including cholesterol. We discuss the problem concerning dietary lipids and others for the prevention of atherosclerosis.

[Clinical science relating atherosclerotic diseases and hypertriglyceridemia].

Recent epidemiologic studies and meta-analysis with triglyceride levels are revealing that hypertriglyceridemia is associated with coronary heart diseases independent of other coronary risk factors, although the direct effect of serum triglycerides to atherosclerotic lesion is still uncertain. Multiple genetic and environmental factors from familial hyperlipidemia to food and alcohol intake are implicated in elevating triglycerides. Especially, a number of investigators demonstrated a relationship between atherosclerotic diseases and postprandial hyperlipidemia, which may lead to nonfasting TG elevation. The purpose of this article is to review several clinical studies relating serum fasting and nonfasting triglyceride levels and coronary heart disease, and to discuss whether hypertriglyceridemia initiates atherosclerosis or plays a role as a biomarker for metabolic abnormalities.

Butyrate attenuates inflammation and lipolysis generated by the interaction of adipocytes and macrophages.

AIM: Paracrine interaction between macrophages and adipocytes in obese visceral fat tissues is thought to be a trigger of chronic inflammation. The immunomodulatory effect of the short chain fatty acid, butyric acid, has been demonstrated. We hypothesize that sodium butyrate (butyrate) attenuates inflammatory responses and lipolysis generated by the interaction of macrophages and adipocytes. METHODS: Using contact or transwell co-culture methods with differentiated 3T3-L1 adipocytes and RAW264.7 macrophages, we investigated the effects of butyrate on the production of tumor necrosis factor alpha (TNF-α), monocyte chemoattractant protein 1 (MCP-1), interleukin 6 (IL-6), and the release of free glycerol, free fatty acids (FFAs) into the medium. We also examined the activity of nuclear factor-kappaB (NF-κB) and the phosphorylation of mitogen-activated protein kinases (MAPKs) in co-cultured macrophages, as well as lipase activity and expression in co-cultured adipocytes. RESULTS: We found increased production of TNF-α, MCP-1, IL-6, and free glycerol, FFAs in the co-culture medium, and butyrate significantly reduced them. Butyrate inhibited the phosphorylation of MAPKs, the activity of NF-κB in co-cultured macrophages, and suppressed lipase activity in co-cultured adipocytes. Lipase inhibitors significantly attenuated the production of TNF-α, MCP-1 and IL-6 in the co-culture medium as effectively as butyrate. Butyrate suppressed the protein production of adipose triglyceride lipase, hormone sensitive lipase, and fatty acid-binding protein 4 in co-cultured adipocytes. Pertussis toxin, which is known to block GPR41 completely, inhibited the antilipolysis effect of butyrate. CONCLUSION: Butyrate suppresses inflammatory responses generated by the interaction of adipocytes and macrophages through reduced lipolysis and inhibition of inflammatory signaling.

Increased serum cholesterol esterification rates predict coronary heart disease and sudden death in a general population.

OBJECTIVE: Lecithin:cholesterol acyltransferase (LCAT) is thought to be important in reverse cholesterol transport. However, its association with coronary heart disease (CHD) and sudden death is controversial. APPROACH AND RESULTS: We prospectively studied 1927 individuals from the general population. Serum concentrations of apolipoprotein A-I, A-II, B, C-II, C-III, E, and LCAT activity measured as a serum cholesterol esterification rate were evaluated. We documented 61 events of CHD and sudden death during 10.9 years of follow-up. After adjustment for age and sex, LCAT activity was significantly associated with the risk of CHD and sudden death (hazard ratio, 3.02; 95% confidence interval, 1.49-6.12; P=0.002). In multivariate analysis adjusted for age, sex, current smoking status, history of diabetes mellitus, body mass index, systolic blood pressure, serum total cholesterol, and serum high-density lipoprotein cholesterol concentrations, the hazard ratio of LCAT activity for the risk of CHD and sudden death remained significant (hazard ratio, 3.07; 95% confidence interval, 1.35-7.01; P=0.008). However, when it was analyzed for men and women separately, this association remained significant only in women. CONCLUSIONS: Increased LCAT activity measured as a serum cholesterol esterification rate was a risk for CHD and sudden death in a Japanese general population.

Fasting remnant lipoproteins can predict postprandial hyperlipidemia.

BACKGROUND: Hypertriglyceridemia and postprandial hyperlipidemia is thought to play an important role in atherosclerosis, but to select patients at high-risk for cardiovascular diseases is difficult with triglycerides (TG) alone in these patients. METHODS: To predict postprandial hyperlipidemia without inconvenient test meal loading, we examined lipid concentrations before and after test meal loading and fasting adiponectin, and investigated which of these other than TG were significant during the fasting period in 45 healthy individuals (men: women, 26:19). RESULTS: TG, remnant-like particle-cholesterol and -triglyceride (RemL-C, RLP-C, and RLP-TG), and TG/apolipoprotein(apo)B were significantly elevated after loading and fasting values significantly and positively correlated with incremental area under the curve (iAUC) (r=0.80, r=0.79, r=0.63, r=0.58, r=0.54; p<0.0001). Fasting adiponectin positively correlated with fasting high-density lipoprotein-cholesterol (r=0.43, p<0.005) and apoA-I (r=0.34, p<0.05), and negatively correlated with iAUC of TG, RemL-C, RLP-C, RLP-TG, and TG/apoB (r=-0.37, r=-0.41, r=-0.37, r=-0.36, r=-0.37; p<0.05). We constructed the model of multivariable linear regression analysis without fasting TG. In the sex-, BMI-, age-, and waist circumference-adjusted analysis of postprandial TG elevation 2 h after test meal loading in all participants, RemL-C, RLP-C, RLP-TG, and TG/apoB were significant factors, but adiponectin was not. CONCLUSION: Fasting triglyceride-rich lipoprotein-related values, especially RemL-C, RLP-C, RLP-TG, and TG/apoB are useful predictors of postprandial hyperlipidemia in young healthy individuals. Although fasting adiponectin concentration correlated with the iAUCs for TG, RemL-C, RLP-C, RLP-TG, and TG/apoB, it was not a significant predictor of postprandial hyperlipidemia in multivariable linear regression analysis.

[What is a good marker for serum cholesterol to identify high-risk patients at general health checks?].

Conventional measurement of lipid concentrations includes total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), and triglycerides (TG). Several guidelines for cardiovascular diseases recommend using LDL-C as the primary target of therapy in conjunction with assessing risk factors for cardiovascular diseases (CVD); however, emerging findings have revealed that lowering LDL-C to the goal with statins is not enough to prevent primary and secondary CVD. Thus, we need new parameters to better integrate residual risks into CVD risk stratification. Recently, non-HDL-C, apolipoprotein B (apoB), and LDL-C/HDL-C have been suggested. Non-HDL-C, indicating the cholesterol contents of all atherogenic lipoproteins and retaining continuity with the concept of cholesterol, is quickly computed by subtracting HDL-C from TC, needs no additional costs, and includes atherogenic TG-rich lipoproteins, called remnant lipoproteins. In addition, non-HDL-C has been shown to be an excellent predictor of CVD, free from dietary variations. ApoB, the number of atherogenic lipoproteins, is also a valuable parameter with slightly better performance than non-HDL-C in epidemiological studies, but it costs more and takes longer than conventional lipid examinations. Several lipid parameters, such as TC/HDL-C, non-HDL-C/HDL-C, LDL-C/HDL-C, are also available in clinical practice and epidemiological study; however, we should note that LDL-C/HDL-C is not reliable in cases of high TG. Thus, in general health checks, we should first pay attention to the absolute values of LDL-C, HDL-C, and TG for the diagnosis and subsequently use non-HDL-C, apoB, and other parameters, considering the pathophysiological condition, convenience, and costs.

Butyrate enhancement of inteleukin-1ß production via activation of oxidative stress pathways in lipopolysaccharide-stimulated THP-1 cells.

In inflammatory bowel diseases, interleukin-1ß production is accelerated. Butyrate, a short chain fatty acid, plays an important role in inflammatory bowel diseases. We investigated the effect of butyrate on interleukin-1ß production in macrophage and elucidated its underlying mechanism. We stimulated THP-1 cells, a human premonocytic cell line, by lipopolysaccharide alone and by butyrate with lipopolysaccharide. Butyrate with lipopolysaccharide increased interleukin-1ß production more than lipopolysaccharide alone. Butyrate with lipopolysaccharide increased caspase-1 activity more than lipopolysaccharide alone. As for the phosphorylation pathway, PD98059 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor) decreased caspase-1 activity and interleukin-1ß production to approximately 50% of the controls. Pertussis toxin (G protein-coupled signal transduction pathway inhibitor) also reduced interleukin-1ß production to approximately 50%. Butyrate with lipopolysaccharide increased reactive oxygen species levels more than lipopolysaccharide alone. The addition of N-acetyl L-cysteine reduced reactive oxygen species levels to a level similar to that of lipopolysaccharide alone. Butyrate with lipopolysaccharide increased nitric oxide production more than lipopolysaccharide alone, and the addition of N-acetyl L-cysteine reduced the elevated amount of nitric oxide. In conclusions, butyrate enhances interleukin-1ß production by activating caspase-1, via reactive oxygen species, the phosphorylation of MAPK, and G protein mediated pathways in lipopolysaccharide stimulated THP-1 cells.