Suppressive effect of coffee on lipopolysaccharide-induced hepatitis in D-galactosamine-sensitized rats

Caffeine Improves Heart Rate Without Improving Sepsis Survival

INTRODUCTION

Caffeine is consumed on a daily basis for its nervous system stimulant properties and is a global adenosine receptor antagonist. Because adenosine receptors have been found to play a major role in regulating the immune response to a septic insult, we investigated if caffeine consumption prior to a septic insult would alter immunological and physiological responses, as well as survival.

METHODS

Two separate experimental designs were used, both using outbred female ICR mice. In the first experiment, mice were administered 20 mg/kg of caffeine (equal to 2-3 cups of coffee for a human) or normal saline intraperitoneally at the time of cecal ligation and puncture (CLP). Immunological parameters including cytokines and local cell recruitment were measured. In the second experiment, caffeine (10 mg/kg per hour) was delivered continuously for 24 h via a subcutaneous infusion pump placed the day prior to CLP, and hemodynamic parameters were examined. In both experiments, survival was followed for 5 days.

RESULTS

A single dose of caffeine at the initiation of sepsis did not alter survival. This single dose of caffeine did significantly increase in plasma levels of the chemokine KC 6 h after the onset of sepsis compared with septic mice given normal saline. There were no changes in interleukin 6 (IL-6) or IL-10 levels in the caffeine groups. Peritoneal lavages performed 24 h after CLP showed no difference in the levels of IL-6, tumor necrosis factor, KC, macrophage inflammatory protein 1, IL-10, or the IL-1 receptor antagonist between caffeine- and normal saline-treated mice. In addition, the lavages yielded similar numbers of cells (4.1 × 10 vehicle vs. 6.9 × 10 caffeine) and bacterial colony-forming units (CFUs, 4.1 million CFUs vehicle vs. 2.8 million CFUs caffeine). In the infusion group, caffeine also did not alter survival. However, caffeine infusion did increase the heart rate prior to CLP and prevented the decline in heart rate after CLP.

CONCLUSION

Caffeine increased the heart rate in mice but does not impact cytokine responses or survival during the acute phase of a polymicrobial sepsis challenge. These data indicate that patients consuming caffeine will not be at risk for increased sepsis mortality.

Reduced Lipopolysaccharide (LPS)-Induced Nitric Oxide Production in Peritoneal Macrophages and Inhibited LPS-Induced Lethal Shock in Mice by a Sugar Cane (Saccharum officinarumL.) Extract

A sugar cane extract (SCE) has been found to have an immunostimulating effect in several animals. Lipopolysaccharide (LPS) is known to induce endotoxin shock via the production of inflammatory modulators such as tumor necrosis factor (TNF)-alpha and nitric oxide (NO). We examined in the present study the effects of SCE on the TNF-alpha and NO production in LPS-stimulated mice peritoneal cells and the endotoxin shock in mice. The supplementation of SCE to peritoneal macrophages cultured with LPS resulted in a significant decrease in NO production. All the mice injected intraperitoneally with LPS and D-galactosamine (LPS+GalN) died within 24 h. However, a peritoneal injection, but no intravenous or oral administration, of SCE (500-1,000 mg/kg) at 3 to 48 h before the LPS+GalN-challenge resulted in a significantly improved survival rate. These results suggest that SCE had a protective effect on LPS-induced endotoxin shock via one of possible mechanisms involving the suppression of NO production in the mouse peritoneal cavity.

Coffee consumption and risk of cancers: a meta-analysis of cohort studies

Background

Coffee consumption has been shown to be associated with cancer of various sites in epidemiological studies. However, there is no comprehensive overview of the substantial body of epidemiologic evidence.

Methods

We searched MEDLINE, EMBASE, Science Citation Index Expanded and bibliographies of retrieved articles. Prospective cohort studies were included if they reported relative risks (RRs) and corresponding 95% confidence intervals (CIs) of various cancers with respect to frequency of coffee intake. We did random-effects meta-analyses and meta-regressions of study-specific incremental estimates to determine the risk of cancer associated with 1 cup/day increment of coffee consumption.

Results

59 studies, consisting of 40 independent cohorts, met the inclusion criteria. Compared with individuals who did not or seldom drink coffee per day, the pooled RR of cancer was 0.87 (95% CI, 0.82-0.92) for regular coffee drinkers, 0.89 (0.84-0.93) for low to moderate coffee drinkers, and 0.82 (0.74-0.89) for high drinkers. Overall, an increase in consumption of 1 cup of coffee per day was associated with a 3% reduced risk of cancers (RR, 0.97; 95% CI, 0.96-0.98). In subgroup analyses, we noted that, coffee drinking was associated with a reduced risk of bladder, breast, buccal and pharyngeal, colorectal, endometrial, esophageal, hepatocellular, leukemic, pancreatic, and prostate cancers.

Conclusions

Findings from this meta-analysis suggest that coffee consumption may reduce the total cancer incidence and it also has an inverse association with some type of cancers.

Coffee consumption and risk of cancers: a meta-analysis of cohort studies

BACKGROUND

Coffee consumption has been shown to be associated with cancer of various sites in epidemiological studies. However, there is no comprehensive overview of the substantial body of epidemiologic evidence.

METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded and bibliographies of retrieved articles. Prospective cohort studies were included if they reported relative risks (RRs) and corresponding 95% confidence intervals (CIs) of various cancers with respect to frequency of coffee intake. We did random-effects meta-analyses and meta-regressions of study-specific incremental estimates to determine the risk of cancer associated with 1 cup/day increment of coffee consumption.

RESULTS

59 studies, consisting of 40 independent cohorts, met the inclusion criteria. Compared with individuals who did not or seldom drink coffee per day, the pooled RR of cancer was 0.87 (95% CI, 0.82-0.92) for regular coffee drinkers, 0.89 (0.84-0.93) for low to moderate coffee drinkers, and 0.82 (0.74-0.89) for high drinkers. Overall, an increase in consumption of 1 cup of coffee per day was associated with a 3% reduced risk of cancers (RR, 0.97; 95% CI, 0.96-0.98). In subgroup analyses, we noted that, coffee drinking was associated with a reduced risk of bladder, breast, buccal and pharyngeal, colorectal, endometrial, esophageal, hepatocellular, leukemic, pancreatic, and prostate cancers.

CONCLUSIONS

Findings from this meta-analysis suggest that coffee consumption may reduce the total cancer incidence and it also has an inverse association with some type of cancers.

Methylxanthines, inflammation, and cancer: fundamental mechanisms

Methylxanthines are an integral part of everyday food and drink consumption even though the majority of humans do not identify them by their chemical name. The breakthrough in understanding the action(s) of methylxanthines was in large part due to the understanding that methylxanthines can function as antagonists of adenosine receptors. This represented an example of scientific search and was instructive in view of both new therapeutic options and alarming realizations. It was the subsequent demonstration of the in vivo critical role of A2A adenosine receptors in controlling excessive collateral inflammatory damage that attracted the attention of immunologists to the A2A-adenosine-receptor-antagonizing methylxanthines. We summarize here data showing that caffeine is capable of preventing the inhibition of antitumor T cells in a hypoxic tumor microenvironment. On the other hand, caffeine may exacerbate liver damage by weakening the tissue-protecting A2A adenosine receptor signaling during episodes of acute liver inflammation. However, methylxanthines may also prevent the excessive hepatic connective tissue deposition that is associated with the progression of chronic hepatitis to cirrhosis, which is one of the common causes of mortality.

Protective effects of coffee-derived compounds on lipopolysaccharide/D-galactosamine induced acute liver injury in rats

OBJECTIVES

The protective effects of coffee-derived compounds on lipopolysaccharide/D-galactosamine (LPS/D-GalN) induced acute liver injury in rats were investigated.

METHODS

Wistar rats were orally administered saline (control) or one of the test compounds (caffeine, chlorogenic acid, trigonelline, nicotinic acid or eight pyrazinoic acids) at a dose of 100 mg/kg, respectively. This was followed by intraperitoneal injection with LPS (100 mug/kg)/D-GalN (250 mg/kg) 1 h after administration of the test compounds. Blood samples were collected up to 12 h after LPS/D-GalN injection, followed by determination of plasma aspartate aminotransferase, alanine aminotransferase, tumour necrosis factor alpha (TNF-alpha) and interleukin 10 (IL-10) levels.

KEY FINDINGS

Plasma aspartate aminotransferase and alanine aminotransferase levels were significantly increased after LPS/D-GalN-treatment, but were suppressed by pretreatment with caffeine (n = 5), nicotinic acid, non-substituted pyrazinoic acid or 5-methylpyrazinoic acid (n = 6, respectively) 12 h after LPS/D-GalN-treatment (P < 0.01, respectively). Moreover, the animals pretreated with these test compounds showed significantly higher survival rates (83-100%) compared with the control (23%). Only pretreatment with caffeine significantly suppressed the LPS/D-GalN induced elevation of plasma TNF-alpha levels 1 and 2 h after LPS/D-GalN-treatment (P < 0.01, respectively). Pretreatment with caffeine, nicotinic acid or non-substituted pyrazinoic acid activated the LPS/D-GalN induced elevation of plasma IL-10 levels at 1 and 2 h, although there were no statistically significant differences in IL-10 levels between control and nicotinic acid or non-substituted pyrazinoic acid treated rats.

CONCLUSIONS

The results suggest that caffeine, nicotinic acid, non-substituted pyrazinoic acid and 5-methylpyrazinoic acid can protect against LPS/D-GalN induced acute liver injury, which may be mediated by the reduction of TNF-alpha production and/or increasing IL-10 production.

Joint effects of coffee consumption and serum gamma-glutamyltransferase on the risk of liver cancer

Only three Japanese prospective studies have suggested an inverse association between coffee drinking and liver cancer risk. No prospective studies on the association between serum gamma-glutamyltransferase (GGT) and liver cancer risk have been reported. We aimed to determine the single and joint associations of coffee consumption and serum GGT with the risk of primary liver cancer. Study cohorts included 60,323 Finnish participants who were 25-74 years of age and free of any cancer at baseline. During a median follow-up period of 19.3 years (interquartile range: 9.3-29.2 years), 128 participants were diagnosed with an incident liver cancer. The multivariable-adjusted (age, sex, alcohol consumption, education, smoking, diabetes and chronic liver disease at baseline and during follow-up, and body mass index) hazards ratios of liver cancer in participants who drank 0-1, 2-3, 4-5, 6-7, and > or =8 cups of coffee daily were 1.00, 0.66, 0.44, 0.38, and 0.32 (P for trend = 0.003), respectively. Further adjustment for serum GGT in subgroup analysis affected the results only slightly. The multivariable-adjusted and coffee-adjusted hazard ratio of liver cancer for the highest versus the lowest quartile of serum GGT was 3.13 (95% confidence interval = 1.22-8.07). The multivariable-adjusted inverse association between coffee consumption and liver cancer risk persisted when stratified by baseline factors: age more/less than 50 years, current smoker/never smoked/ever smoked, alcohol drinker/never drinker, obese/nonobese, and the highest/lowest three quartiles of serum GGT. A combination of very low coffee consumption and high level of serum GGT was associated with nearly nine-fold increased risk.

CONCLUSION

Coffee drinking has an inverse and graded association with the risk of liver cancer. High serum GGT is associated with an increased risk of liver cancer.

[Pharmacological bases of coffee nutrients for diabetes prevention]

With an increasing number of studies describing the negative correlation of coffee consumption and the risk for type 2 diabetes mellitus, we were compelled to elucidate the nutrients which bring pharmacological effects on risk reduction for diabetes. In this review, the author's interest is focused on chlorogenic and caffeic acids derived from lightly roasted coffee beans, as well as nicotinic acid, volatile Maillard reaction products (vMRPs), and another structurally unknown compound contained in heavily roasted beans. Caffeine is a common compound in both lightly and heavily roasted beans and its anti-inflammatory effects on degenerative diseases such as diabetes mellitus has been reevaluated recently. The prophylactic effects of coffee on diabetes involve pleiotropy of plural components in accordance to the degree of the roasting. A new concept of nutritional blended coffee may be important to optimize the prophylactic effects of coffee on lowering the risk factors of diabetes and delaying the progress of diabetes complications as well.

1,3,7-trimethylxanthine (caffeine) may exacerbate acute inflammatory liver injury by weakening the physiological immunosuppressive mechanism

The genetic elimination of A2A adenosine receptors (A2AR) was shown to disengage the critical immunosuppressive mechanism and cause the dramatic exacerbation of acute inflammatory tissue damage by T cells and myeloid cells. This prompted the evaluation of the proinflammatory vs the anti-inflammatory effects of the widely consumed behavioral drug caffeine, as the psychoactive effects of caffeine are mediated largely by its antagonistic action on A2AR in the brain. Because caffeine has other biochemical targets besides A2AR, it was important to test whether the consumption of caffeine during an acute inflammation episode would lead to the exacerbation of immune-mediated tissue damage. We examined acute and chronic treatment with caffeine for its effects on acute liver inflammation. It is shown that caffeine at lower doses (10 and 20 mg/kg) strongly exacerbated acute liver damage and increased levels of proinflammatory cytokines. Because caffeine did not enhance liver damage in A2AR-deficient mice, we suggest that the potentiation of liver inflammation was mediated by interference with the A2AR-mediated tissue-protecting mechanism. In contrast, a high dose of caffeine (100 mg/kg) completely blocked both liver damage and proinflammatory cytokine responses through an A2AR-independent mechanism. Furthermore, caffeine administration exacerbated liver damage even when mice consumed caffeine chronically, although the extent of exacerbation was less than in "naive" mice that did not consume caffeine before. This study suggests an unappreciated "man-made" immunological pathogenesis whereby consumption of the food-, beverage-, and medication-derived adenosine receptor antagonists may modify an individual's inflammatory status and lead to excessive organ damage during acute inflammation.

Coffee consumption and risk of liver cancer: a meta-analysis

BACKGROUND & AIMS

Mounting evidence indicates that coffee drinking may protect against liver injury and lower the risk of liver cancer. We quantitatively assessed the relation between coffee consumption and the risk of liver cancer in a meta-analysis of epidemiologic studies.

METHODS

Relevant studies were identified by searching MEDLINE (from 1966 to February 2007) and the reference lists of retrieved articles. We included cohort and case-control studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) of primary liver cancer or hepatocellular carcinoma by quantitative categories of coffee consumption. Study-specific RRs were pooled using a random-effects model.

RESULTS

Four cohort and 5 case-control studies, involving 2260 cases and 239,146 noncases, met the inclusion criteria. All studies observed an inverse relation between coffee consumption and risk of liver cancer, and in 6 studies the association was statistically significant. Overall, an increase in consumption of 2 cups of coffee per day was associated with a 43% reduced risk of liver cancer (RR, 0.57; 95% CI, 0.49-0.67). There was no statistically significant heterogeneity among studies (P = .17). In stratified analysis, the summary RRs of liver cancer for an increase in consumption of 2 cups of coffee per day were 0.69 (95% CI, 0.55-0.87) for persons without a history of liver disease and 0.56 (95% CI, 0.35-0.91) for those with a history of liver disease.

CONCLUSIONS

Findings from this meta-analysis suggest that an increased consumption of coffee may reduce the risk of liver cancer.

Differential effects of dietary casein and soybean protein isolate on lipopolysaccharide-induced hepatitis in D-galactosamine-sensitized rats

Effects of dietary protein type on lipopolysaccharide (LPS)-induced hepatitis, as assessed by plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, were investigated in D-galactosamine (GalN)-sensitized rats. The plasma ALT and AST activities in rats fed on 25% soybean protein isolate (SPI) diet were significantly suppressed to about 1/4 and 1/5 of the values in rats fed on 25% casein diet, respectively, 8 h after the injection of LPS + GalN. Although hepatic ALT and AST activities of normal rats were also lower in the SPI group than in the casein group, this could not explain the differences in plasma enzyme activities between the two groups. The hepatic glutathione concentration of normal rats was lower in the SPI group than in the casein group, but it was reversed in rats injected with drugs. The results suggest that SPI can protect animals from LPS + GalN-induced hepatitis, and that the hepatic glutathione level may participate in the effects of SPI.