The association between specific nutritional antioxidants and manifestation of colorectal cancer

Link between risk of colorectal cancer and serum vitamin E levels: A meta-analysis of case-control studies

BACKGROUND

The effect of low serum vitamin E levels on the risk of colorectal cancer (CRC) remains inconclusive. This meta-analysis aims to synthesize relevant studies to evaluate the association between serum vitamin E and the risk of CRC based on case-control studies.

METHODS

Potentially relevant studies were selected by searching PubMed, EMBASE, and China National Knowledge Infrastructure databases according to inclusion and exclusion criteria. The association between serum vitamin E levels and CRC was estimated by the weighted mean difference (WMD) and 95% confidence interval (CI) using a random-effects model. Heterogeneity was evaluated using Q test and I statistic. Subgroup analysis was conducted to explore sources of heterogeneity. Sensitivity analysis was performed to reveal stability and reliability.

RESULTS

A total of 10 papers with 11 studies, including 6431 subjects with 520 CRC patients and 5981 controls, were included in this present meta-analysis. The results indicated that compared with healthy controls, patients with CRC showed lower concentrations of serum vitamin E (WMD = -2.994 μmol/L, 95% CI = -4.395 to -1.593). Ethnicity subgroup analysis indicated that the serum vitamin E levels were lower in European (WMD = -1.82 μmol/L, 95% CI = -3.00 to -0.65), but not in Asian. Control-source subgroup analysis revealed that a significant association was observed in subgroup with hospital-based controls (WMD = -3.43 μmol/L, 95% CI = -6.27 to -0.59), but not in those with population-based controls. Sensitivity analysis suggested no significant difference in the pooled estimates, indicating stable results.

CONCLUSIONS

CRC is associated with a lower concentration of serum vitamin E. However, necessary prospective cohort studies should be conducted to assess the effect of serum vitamin E on the risk of CRC in the future.

A prospective study of the immune system activation biomarker neopterin and colorectal cancer risk

BACKGROUND

Neopterin may be relevant for colorectal cancer (CRC) development, as a biomarker of cellular immune activity exerting pleiotropic effects on cellular ageing, oxidative stress, and inflammation. So far, the association between prediagnostic neopterin and colon and rectal cancer risk has not been evaluated in human populations.

METHODS

A nested case-control study was conducted within the European Prospective Investigation into Cancer and Nutrition cohort using data on plasma concentrations of total neopterin (T-N, sum of neopterin and 7,8-dihydroneopterin) in 830 incident CRC case patients (561 colon and 269 rectal) matched within risk sets to 830 control participants. A subsequent replication study used data from the Hordaland Health Study, where 173 CRC case patients have been diagnosed among 6594 healthy participants over 12 years of follow-up.

RESULTS

After multivariable adjustment for a priori chosen CRC risk factors, a "U-shaped" association of T-N with CRC was revealed. Compared with the second quintile of the T-N distribution, the relative risks for the first, third, fourth, and fifth quintiles were 2.37 (95% CI = 1.66 to 3.39), 1.24 (95% CI = 0.87 to 1.77), 1.55 (95% CI = 1.08 to 2.22), and 2.31 (95% CI = 1.63 to 3.27), respectively. Replication of these associations within the Hordaland Health Study yielded similar results. No differences have been observed when the associations were explored by colon and rectal cancer site (two-sided P difference = .87) and after excluding case patients diagnosed within the first four follow-up years.

CONCLUSIONS

These novel findings provide evidence of the role of both suppressed and activated cell-mediated immunity as reflected by prediagnostic T-N concentrations in the development of CRC.

Immune changes and neurotransmitters: possible interactions in depression?

A disturbed metabolism of catecholamines and other neurotransmitters appears to play a major role in the pathogenesis of neurospychiatric symptoms, such as changes in mood and depression. This symptomatology is common in patients with chronic inflammatory disorders such as infections, autoimmune diseases, or cancer. The pathogenesis of these symptoms is still unclear. Pro-inflammatory stimuli interfere not only with the neural circuits and neurotransmitters of the serotonergic system but also with those of the adrenergic system. The pro-inflammatory cytokine interferon-γ stimulates the biosynthesis of 5,6,7,8-tetrahydrobiopterin (BH4), which is a co-factor for several aromatic amino acid mono-oxygenases and is rate-limiting for the biosynthesis of the neurotransmitter serotonin and the catecholamines dopamine, epinephrine (adrenaline) and norepinephrine (noradrenaline). Interferon-γ triggers the high output of reactive oxygen species in macrophages, which can destroy the oxidation-labile BH4. Recent data suggests that oxidative loss of BH4 in chronic inflammatory conditions can reduce the biosynthesis of catecholamines, which may relate to disturbed adrenergic neurotransmitter pathways in patients.

Immunomodulatory properties of cacao extracts - potential consequences for medical applications

Anti-inflammatory properties of cacao, fruits of Theobroma cacao L. (Sterculiaceae), are well documented, and therapeutic applications are described for gastrointestinal, nervous, and cardiovascular abnormalities. Most, if not all of these disease conditions involve inflammation or immune activation processes. The pro-inflammatory cytokine interferon-γ (IFN-γ) and related biochemical pathways like tryptophan breakdown by indoleamine 2,3-dioxygenase (IDO) and neopterin formation are deeply involved in their pathogenesis. Neopterin concentrations and the kynurenine to tryptophan ratio (Kyn/Trp, an estimate of IDO activity) are elevated in a significant proportion of patients with virus infections, cancer, autoimmune syndrome, neurodegeneration, and coronary artery disease. Moreover, higher neopterin and Kyn/Trp concentrations are indicative for poor prognosis. When investigating the effect of aqueous or ethanolic extracts of cacao on IFN-γ, neopterin and Kyn/Trp concentrations in mitogen-stimulated human peripheral blood mononuclear cells, breakdown of tryptophan by IDO, and formation of neopterin and IFN-γ were dose-dependently suppressed. The effects observed in the cell-based assays are associated with the antioxidant activity of the cacao extracts as determined by the cell-free oxygen radical absorption capacity assay. The influence of cacao extracts on IDO activity could be of particular relevance for some of the beneficial health effects ascribed to cacao: tryptophan breakdown by IDO is strongly involved in immunoregulation, and the diminished availability of tryptophan limits the biosynthesis of neurotransmitter serotonin. The inhibition of tryptophan breakdown by cacao constituents could thus be relevant not only for immune system restoration in patients, but also contribute to mood elevation and thereby improve quality of life. However, the available data thus far are merely in vitro only and future studies need to investigate the influence of cacao on tryptophan metabolism in vivo.

Potential role of antioxidant food supplements, preservatives and colorants in the pathogenesis of allergy and asthma

A significant increase in the incidence of allergy and asthma has been observed during the past decades. The background of this phenomenon has not been well explained, but changes in lifestyle and habits are heavily discussed as contributing factors. Among these is a too clean environment, which may predispose individuals to increased sensitivity to allergic responses. Also the increase in dietary supplements including preservatives and colorants may contribute to this. In vitro, we and others have shown in freshly isolated human peripheral blood mononuclear cells that antioxidant compounds like vitamins C and E as well as food preservatives and colorants exert significant suppressive effects on the Th1 immune activation cascade. The effects observed may be based on the interaction of antioxidant compounds with proinflammatory cascades involving important signal transduction elements such as nuclear factor-κB. Although only obtained in vitro, these results show an anti-inflammatory property of compounds which could shift the Th1-Th2-type immune balance towards Th2-type immunity. This review article discusses the potential role of increased use of antioxidant food supplements as well as preservatives and colorants in the increase in allergy and asthma in the Western world.

In vitro testing for anti-inflammatory properties of compounds employing peripheral blood mononuclear cells freshly isolated from healthy donors

INTRODUCTION

Inflammation is crucially involved in a variety of diseases like autoimmune syndromes, cardiovascular and neurodegenerative disorders, cancer, sepsis and allograft rejection.

METHODS

Freshly isolated human peripheral blood mononuclear cells (PBMCs) are used as a screening assay for anti-inflammatory properties of compounds. Determinations of neopterin production by ELISA and of tryptophan degradation by HPLC are used as read-outs. Results are compared with further markers of immune response and oxidative stress.

RESULTS

Phytohaemagglutinin induced significant tryptophan degradation and neopterin formation in PBMC, which correlated with IFN-γ, TNF-α, soluble cytokine receptors and isoprostane-8. Addition of vitamin C and E suppressed the responses dose-dependently.

DISCUSSION

The determination of tryptophan degradation and neopterin production in PBMC reflects various pro- and anti-inflammatory cascades that are of relevance also in patients. It constitutes a robust and reliable approach to screen anti-inflammatory or immunosuppressive drugs and may improve throughput, speed and cost-effectiveness in drug discovery.

The comparative study of serum iron, copper, and zinc levels between bladder cancer patients and a control group

OBJECTIVE

A relatively wide range of trace elements are known to play important roles in biological processes, including the oxidative processes. Oxidative processes are one of the mechanisms involved in both incidence and recurrence of bladder cancer. In the present study, the concentration of iron (Fe), copper (Cu) and zinc (Zn) were determined in the serum of patients with bladder cancer in comparison to healthy subjects.

MATERIALS AND METHODS

This cross-sectional study was conducted on 51 patients with bladder cancer and 58 healthy volunteers after age, sex, and smoking habits were matched. After overnight fasting, samples were collected. The concentrations of Fe, Cu, and Zn were measured by flame atomic absorption spectroscopy and comparisons were made using Student's t-test.

RESULTS

There was a significant increase in mean Cu and Cu/Zn serum level in bladder cancer patients compared to the control group (P < 0.001). In contrast, the serum zinc level in patients having bladder cancer was significantly lower than in the control group (P < 0.05). Moreover, the serum iron level was significantly lower in the patients than the control group (P < 0.001).

CONCLUSIONS

In the present study, a relationship was seen between the level of trace elements and the occurrence of bladder cancer, suggesting that an increase in the serum level of Cu and a decrease in the levels of Zn and Fe might be important causes of bladder cancer occurrence; however, defining such a cause-and-effect relationship needs several prospective studies to be done, which seems necessary with regard to the high prevalence of this cancer.

Hyperhomocysteinaemia and immune activation in patients with cancer

BACKGROUND

Recently, homocysteine production was observed in tumour cell lines and homocysteine was proposed as a tumour marker. Furthermore, homocysteine production by activated immunocompetent cells was demonstrated.

METHODS

In this study, homocysteine metabolism and immune activation status were investigated in 128 patients suffering from various types of cancer (haematological disorders, lung cancer, gastrointestinal tumours, gynaecological cancer and tumours of other localisation) and healthy age-matched controls.

RESULTS

A high percentage of patients (39.1%) showed moderate hyperhomocysteinaemia, while cysteine, folate and vitamin B(12) concentrations were within reference ranges. Most patients were found to have elevated concentrations of the immune activation and inflammation markers neopterin and C-reactive protein (CRP), as well as a higher erythrocyte sedimentation rate (ESR). Patients of different cancer groups differed significantly regarding vitamin B(12) and neopterin concentrations; higher B(12) levels were also associated with tumour progression. Univariate regression analysis showed that CRP, ESR and neopterin were suited best to predict death. In multivariate analysis, neopterin was best suited to predicting death, while homocysteine and B vitamins were not associated with patient outcome. Homocysteine concentrations were correlated with folate and cysteine levels. Higher neopterin concentrations coincided with lower folate concentrations, but higher vitamin B(12) concentrations.

CONCLUSIONS

Associations between neopterin and folate concentrations may indicate that cellular immune activation might partly contribute to the development of folate deficiency in cancer patients, thus possibly also impairing homocysteine remethylation.

Hyperhomocysteinemia and Immune Activation

Hyperhomocysteinemia is an established risk factor for atherosclerosis, thrombosis and other vascular diseases. Homocysteine auto-oxidation is considered to be crucially involved in the pathogenesis of these diseases. However, the question remains to be elucidated whether vitamin deficiency and homocysteine accumulation are causal for disease development or rather comprise a secondary phenomenon. Most diseases accompanied by hyperhomocysteinemia are also associated with ongoing activation of the immune system. In vitro experiments show homocysteine to accumulate in stimulated peripheral blood mononuclear cells. In patients with coronary heart disease, with rheumatoid arthritis and in patients with dementia, an association between cellular immune activation and homocysteine metabolism is found. Homocysteine concentrations not only correlate inversely with folate concentrations, they also show a positive relationship with concentrations of immune activation markers like neopterin. Moreover, in patients with various kinds of dementia, increased concentrations of serum peroxides, homocysteine and neopterin correlate with each other. Studies support a role of immune system activation in the development of hyperhomocysteinemia. Stimulation and proliferation of immune cells may lead to the production of reactive oxygen species that may oxidize antioxidants and oxidation-sensitive B-vitamins. An enhanced demand for antioxidants as well as folate and vitamin B12 may develop, together with hyperhomocysteinemia, despite sufficient dietary intake.