Urine neopterin concentrations as a marker for successful blastocyst implantation after assisted reproductive technologies.

Successful blastocyst implantation requires intricately orchestrated adaptation processes involving maternal and fetal mediators. The pivotal role of distinct immune response pathways in early pregnancy is widely acknowledged. Pro-inflammatory cytokines, e.g. interferon-gamma (IFN-gamma), are the primary inducers of tryptophan-degrading enzyme indoleamine 2,3-dioxygenase (IDO) and of neopterin biosynthesis by GTP-cyclohydrolase I. IDO activity has been proposed to be of high clinical relevance in the context of pregnancy. To date, insights arising from clinical studies on IDO activity and neopterin concentration during the very early days of pregnancy are still few. Early morning urinary neopterin concentrations in 61 women undergoing assisted reproduction treatment (72 cycles in total) were examined, upon exclusion of infections, daily over a period of 2 weeks after embryo transfer. Twenty of the study participants (28%) became successfully pregnant, and four women experienced abortion. Neopterin concentrations significantly increased after blastocyst transfer when implantation was successful (chi-squared=23.291, P<0.01; Friedman test), opposed to non-significant changes of neopterin in women with unsuccessful treatment (chi-squared=8.203). The steady increase of neopterin concentrations upon blastocyst transfer indicates that heightened production of neopterin in very early phases of pregnancy may serve as an early predictor of successfully progressing pregnancies in humans.

Association between asymmetric dimethylarginine and neopterin in patients with and without angiographic coronary artery disease.

The increase of circulating asymmetric dimethylarginine (ADMA) concentrations, a competitive inhibitor of the nitric oxide synthases, is associated with an increased cardiovascular risk and is considered to play a role in endothelial dysfunction. Recently, ADMA production was observed in stimulated human peripheral mononuclear cells. In this study, we examined a potential relationship between concentrations of ADMA and of the immune activation marker neopterin in patients scheduled for coronary angiography. In a cross-sectional approach, blood concentrations of ADMA, homocysteine, neopterin, folic acid and vitamins B6 and B12 were compared in 2030 patients, which were recruited as participants of the LUdwigshafen RIsk and Cardiovascular Health (LURIC) study. ADMA concentrations did not differ between patients with coronary artery disease (CAD) (mean +/- SD: 0.82 +/- 0.15 micromol/l) and controls (0.81 +/- 0.14 micromol/l; Welch's t-test: P = n.s.). ADMA concentrations correlated with homocysteine (r(s) = 0.207) and vitamin B6 (r(s) = -0.190), and an even stronger correlation with neopterin (r(s) = 0.276; all P < 0.0001) was observed. In conclusion, increased ADMA concentrations in patients at risk for atherosclerosis are associated with increased neopterin concentrations. Data suggest that immune activation may contribute to increased ADMA production in CAD patients.

Immune activation and degradation of tryptophan in coronary heart disease.

BACKGROUND: Inflammation and immune activation appear to be important in the pathogenesis of coronary heart disease (CHD). Cytokine interferon-gamma, which is released during cell-mediated immune responses, induces indoleamine (2,3)-dioxygenase (IDO), an enzyme degrading tryptophan to kynurenine. Therefore, immune stimulation is commonly associated with an increased kynurenine to tryptophan ratio (kyn trp-1) indicative for activated indoleamine (2,3)-dioxygenase and a measurable decline of tryptophan. METHODS: Blood concentrations of kynurenine and free tryptophan and the kynurenine to tryptophan ratio were examined in 35 patients with coronary heart disease verified by coronary angiography and compared with healthy controls. Patients were observed before percutaneous transluminal coronary angioplasty (21 patients: one with artery disease, nine with 2- or 3-artery disease, and five with restenosis). RESULTS AND CONCLUSIONS: Decreased tryptophan concentrations were found in a significant proportion of coronary heart disease patients and coincided with increased kyn trp-1 and also with increased neopterin concentrations, indicating an activated cellular immune response. We conclude that in coronary heart disease immune activation is associated with an increased rate of tryptophan degradation and thereby lowered tryptophan levels. Results may provide a basis for a better understanding of the pathogenesis of mood disturbances and depression in coronary heart disease patients.

Neopterin as a marker for immune system activation.

Increased amounts of neopterin are produced by human monocytes/macrophages upon stimulation with the cytokine interferon-y. Therefore, measurement of neopterin concentrations in body fluids like serum, cerebrospinal fluid or urine provides information about activation of T helper cell 1 derived cellular immune activation. Increased neopterin production is found in infections by viruses including human immunodeficiency virus (HIV), infections by intracellular living bacteria and parasites, autoimmune diseases, malignant tumor diseases and in allograft rejection episodes. But also in neurological and in cardiovascular diseases cellular immune activation indicated by increased neopterin production, is found. Major diagnostic applications of neopterin measurements are, e.g. monitoring of allograft recipients to recognize immunological complications early. Neopterin production provides prognostic information in patients with malignant tumor diseases and in HIV-infected individuals, high levels being associated with poorer survival expectations. Neopterin measurements are also useful to monitor therapy in patients with autoimmune disorders and in individuals with HIV infection. Screening of neopterin concentrations in blood donations allows to detect acute infections in a non-specific way and improves safety of blood transfusions. As high neopterin production is associated with increased production of reactive oxygen species and with low serum concentrations of antioxidants like alpha-tocopherol, neopterin can also be regarded as a marker of reactive oxygen species formed by the activated cellular immune system. Therefore, by neopterin measurements not only the extent of cellular immune activation but also the extent of oxidative stress can be estimated.

Dehydroepiandrosterone, ageing and immune activation.

The age-related decline in dehydroepiandrosterone (DHEA) production is currently attracting attention because of its possible relevance to the etiology and management of a number of age-related clinical disorders. Various abnormalities of immune system function have been described in the elderly. Among them, increased concentrations of neopterin have been reported, which is produced by human monocytes/macrophages upon stimulation by interferon-gamma. In order to examine the relation of serum DHEA to serum neopterin, we studied 281 otherwise healthy outpatients, who visited the physician's office for a medical health check-up. 10% presented with increased neopterin concentrations, 0.4% had increased DHEA sulfate (DHEAs) concentrations. DHEAs concentrations were significantly higher in patients with lower neopterin concentrations (Mann-Whitney test: U=4793, P<0.0001). There existed a rather strong inverse correlation between DHEAs concentrations and serum neopterin concentrations (Spearman's rank correlation: r(s)=-0.221, P<0.0001). The data support the concept that the decrease of DHEA with increasing age is related to immune system activation. Oxidative stress which accompanies immune response may diminish DHEA synthesis.

Increased serum amylase and lipase in fructose malabsorbers.

BACKGROUND: Fructose malabsorption is frequently seen in the general population and is characterised by the inability to absorb fructose efficiently. Due to fructose malabsorption, fructose reaches the colon where it is broken down by bacteria to short fatty acids, CO(2) and H(2). Bloating, cramps, osmotic diarrhea and other symptoms of irritable bowel syndrome are the consequence. We recently found that fructose malabsorption is associated with low plasma folic acid concentrations and low serum tryptophan and zinc. Because fructose malabsorption apparently is associated not only with malabsorption of other nutrients, but also with abdominal discomfort, it was of interest to examine whether mild pancreatitis may be involved. METHODS: We retrospectively examined our data in 159 otherwise healthy adults (110 females, 49 males) aged 14-84 years (mean 45.6+/-14.4 S.D.) with gastrointestinal complaints for serum amylase and serum lipase concentrations. The patients have been tested earlier for fructose malabsorption and lactose maldigestion by measuring breath H(2) concentrations after an oral dose of 25 g fructose and 50 g lactose, respectively, 1 week apart. RESULTS: Fructose malabsorption (H(2) concentrations > or =20 ppm over baseline values) was detected in 107 of 159 individuals (67.3%). These subjects with fructose malabsorption presented with significantly higher serum amylase concentrations (73.1 U/l+/-25.7 S.D.) compared to individuals with normal fructose absorption (59.6 U/l+17.9 S.D; p=0.0009). Fructose malabsorbers also presented with higher serum lipase concentrations (122.0 U/l+/-100.3 S.D.) compared to normals (89.5 U/l+/-46.5 S.D.; p<0.05). To determine whether this finding is a consequence of any sort of malabsorption syndrome or whether it is specific for fructose malabsorption, all subjects were screened for lactose maldigestion. Lactose maldigestion (H(2) concentrations>20 ppm over baseline after lactose loading) was found in 50 of 159 individuals (31.4%). There were no significant differences in either amylase or lipase concentrations in lactose maldigestors. CONCLUSION: Serum amylase and lipase concentrations are higher in subjects with fructose malabsorption compared to normals. Therefore, fructose malabsorption should be considered as a differential diagnosis in moderately elevated serum amylase.

Neopterin production and tryptophan degradation in humans infected by Streptococcus pyogenes.

Streptococcus pyogenes may cause tonsillitis, scarlet fever and so-called "streptococcal toxic shock-like syndrome" (STSS). These streptococci produce exotoxins which are implicated as superantigens in the pathogenesis of STSS and scarlet fever. Using human peripheral blood-derived mononuclear cells in vitro, such toxins were shown to induce neopterin production and degradation of the amino acid tryptophan to metabolites such as kynurenine by activating indoleamine (2,3)-dioxygenase via interferon-gamma. We investigated the sera of seven patients with streptococcal tonsillitis and of four patients with STSS. Those with STSS showed higher serum neopterin concentrations (median: 152 nmol/l; 95th percentile in healthy controls: 8.7 nmol/l) than those with tonsillitis (median: 12 nmol/l). Similarly, kynurenine to tryptophan ratios were increased in tonsillitis and extremely high in patients with STSS. Highly increased neopterin production and tryptophan degradation in patients with STSS suggest an association between a high degree of T cell activation and the severity of the disease manifestation.

Fructose malabsorption is associated with decreased plasma tryptophan.

BACKGROUND: Fructose malabsorption is characterized by the inability to absorb fructose efficiently. As a consequence fructose reaches the colon where it is broken down by bacteria to short fatty acids, CO2, H2, CH4 and lactic acid. Bloating, cramps, osmotic diarrhea and other symptoms of irritable bowel syndrome are the consequence and can be seen in about 50% of fructose malabsorbers. Recently it was found that fructose malabsorption was associated with early signs of depressive disorders. Therefore, it was investigated whether fructose malabsorption is associated with abnormal tryptophan metabolism. METHODS: Fifty adults (16 men, 34 women) with gastrointestinal discomfort were analyzed by measuring breath hydrogen concentrations after an oral dose of 50 g fructose after an overnight fast. They were classified as normals or fructose malabsorbers according to their breath H2 concentrations. All patients filled out a Beck depression inventory questionnaire. Blood samples were taken for plasma tryptophan and kynurenine measurements. RESULTS: Fructose malabsorption (breath deltaH2 production >20 ppm) was detected in 35 of 50 individuals (70%). Subjects with fructose malabsorption showed significantly lower plasma tryptophan concentrations and significantly higher scores in the Beck depression inventory compared to those with normal fructose absorption. CONCLUSIONS: Fructose malabsorption is associated with lower tryptophan levels that may play a role in the development of depressive disorders. High intestinal fructose concentration seems to interfere with L-tryptophan metabolism, and it may reduce availability of tryptophan for the biosynthesis of serotonin (5-hydroxytryptamine). Fructose malabsorption should be considered in patients with symptoms of depression and disturbances of tryptophan metabolism.

Inverse relationship between neopterin and immunoglobulin E.

Polarized human T helper (Th) cells play a key role in the network of the specific immune system compartments. Cell-mediated immune response depends on activation of Th1-type cells, typically producing and releasing interferon-gamma and interleukin-2, whereas activation of Th2-type cells and production of cytokines such as interleukin-4, -5, and -10 are involved in humoral immune response and the production of immunoglobulins. Increased amounts of neopterin are produced during the Th1-type immune response by human monocytes/macrophages upon stimulation with the Th1-derived cytokine interferon-gamma, and thus the determination of neopterin concentrations allows us to monitor Th1-type immune response. We compared serum concentrations of neopterin with immunoglobulin E (IgE), a typical product of the Th2-type immune response, in order to examine the relationship between Th1-type and Th2-type immune system stimulation in 709 healthy outpatients, who visited the physician's office for a medical health checkup. Eleven percent presented with serum neopterin concentrations >8.7 nmol/L; 26% had increased serum concentrations of IgE (>100 kIU/L). There existed an inverse correlation between serum neopterin and IgE concentrations (Spearman's rank correlation coefficient: r(s) = -0.100; P < 0.01) which was stronger when excluding data < or = 8.7 nmol/L neopterin and < or = 100 kIU/L IgE (n = 246; r(s) = -0.519; P < 0.0001). Data indicate that increased serum neopterin concentrations are associated with low serum IgE and increased serum IgE with low serum neopterin concentrations. This finding fully agrees with the current understanding that in humans the activation of Th1 and Th2 cell-mediated immune responses are down-regulating each other.

Immune reaction links disease progression in cancer patients with depression.

Mood disturbances and depression are supposed to have a negative impact on patients' outcome in malignant tumour disease. On the other hand, poor prognosis in cancer patients is associated with chronic immune challenge which is paralleled by enhanced degradation of the essential amino acid tryptophan and thus decreased plasma tryptophan concentrations. Because tryptophan is precursor for the biosynthesis of the neurotransmitter serotonin (= 5-hydroxytryptamine, 5HT), low tryptophan concentrations will lead to decreased availability of serotonin which finally increases the susceptibility for the development of mood disturbances and depression in the patients. Thus, the development of depression in cancer patients may result from chronic cellular immune stimulation. In conclusion, a more aggressive tumour rather than depression will be responsible for worse outcome of cancer patients and will be associated with a more drastic challenge of the immune system, as a side effect leading to neurotransmitter disturbances.

Histamine suppresses neopterin production in the human myelomonocytoma cell line THP-1.

Histamine, an important inflammatory mediator in allergic diseases and asthma, was reported to have modulatory effects on T cells by down-regulating Th1-type cell cytokines like interleukin 2 (IL-2) and interferon-gamma (IFN-gamma). In this study we examined the effect of histamine and the histamine-receptor antagonists cimetidine and diphenhydramine on the production of neopterin after stimulation with IFN-gamma in the myelomonocytoma cell line THP-1. Increasing concentrations of histamine markedly suppressed IFN-gamma induced neopterin formation. Simultaneous preincubation of THP-1 cells with histamine, IFN-gamma and different concentrations of the H(2)-receptor antagonist cimetidine showed a clear antagonizing effect on neopterin formation. In contrast, the H(1)-receptor antagonist diphenhydramine was not able to abrogate the suppressive effect of histamine on neopterin production. Our results suggest, that histamine may be a potent inhibitor of effects or mechanisms induced by IFN-gamma in monocytes/macrophages. Cimetidine, and possibly other H(2)-receptor antagonists, may reverse down-regulatory actions of endogenously formed histamine on activated monocytic cells.

Odd-numbered long-chain fatty acids in propionic acidaemia.

UNLABELLED: In patients with propionic acidaemia (PA), the increased intracellular concentration of propionyl-CoA leads to a relative abundance of odd-numbered long-chain fatty acids (OLCFAs) in body lipids. We investigated the relative amount of OLCFA in erythrocyte membrane lipids over a period of 1-8 years in five patients with early onset PA and present their clinical outcome. After extraction from erythrocyte membrane lipids and esterification, fatty acids were analysed by capillary column gas chromatography. The sum of the OLCFA 15- and 17- carbon saturated and 17-carbon monounsaturated fatty acids (C15:0, C17:0, C17:1) was calculated and expressed as a percentage of the total C14-C22 fatty acids in the sample. Three patients (pccBC-complementation group) presented with a stable clinical course and showed OLCFA values usually below 1.9% (median % +/- SD: 1.4+/-0.5, 1.6+/-0.5, 1.8+/-0.5). Two patients (pccA-complementation group) had a more severe course of the disease and showed higher medians and a broader range of OLCFA levels (2.2+/-1.2 and 2.2+/-0.8). CONCLUSION: Our study shows that odd-numbered long-chain fatty acid concentrations are increased in patients with propionic acidaemia and are higher in those with a more severe clinical course. The value of odd-numbered long-chain fatty acids in the assessment of the phenotypic severity and in the management of propionic acidaemia remains to be proven in a prospective long-term study with more patients of differing phenotype.

Neopterin: a prognostic variable in operations for lung cancer.

BACKGROUND: We studied the prognostic value of preoperatively measured neopterin to predict survival of lung cancer patients. Neopterin is produced and secreted by interferon-gamma-stimulated monocytic cells. High urinary neopterin concentrations are found in patients with viral infections, allograft rejection episodes, and some malignant diseases. In various tumor types high urinary neopterin concentrations are associated with a worse prognosis. METHODS: Preoperative neopterin levels of 110 patients (29 women, 81 men) with lung cancer including 7 patients with small cell lung cancer were measured and related to the time of survival after operation. Patients with clinically suspected stage IIIB lung cancer were not operated and therefore not enrolled in this study. Infectious diseases were not apparent at the time of preoperative urine sampling. Median postoperative follow-up period was 17.4 months. RESULTS: In a univariate analysis, patients with a preoperative neopterin concentration of more than 212 micromol/mol creatinine (4th quartile) were determined to have a significantly lower survival probability. In a multivariate analysis, a neopterin concentration of more than 212 micromol/mol creatinine (p < 0.01) and T-stage status (p < 0.005) were determined to be significantly predictive variables for worse survival prognosis. CONCLUSIONS: Preoperative neopterin proved to be a reliable prognostic factor for survival. Immunology may provide an accurate assessment of tumor aggression and its clinical behavior. In this sense, neopterin can serve as an immunologically based estimation of malignant outgrowth. In patients who are operable by clinical tumor stage but have a high risk for operation, elevated preoperative neopterin may help in the decision for a nonoperative treatment.

Neopterin is an independent prognostic variable in females with breast cancer.

BACKGROUND: Neopterin, produced by human monocytes/macrophages upon stimulation by interferon-gamma, is a sensitive marker for monitoring Th1-cell immune response in humans. In malignant diseases, the frequency of increases in neopterin in the serum and urine of patients depends on tumor stage and type. METHODS: In a retrospective study comprising 129 females with breast cancer, urinary neopterin/creatinine ratios were measured at the time of diagnosis. Tumor characteristics were determined concomitantly. RESULTS: Urinary neopterin was increased in 18% of the patients. It did not correlate with tumor size or lymph node status, but it was influenced by the presence of distant metastases (P <0.05) and by tumor differentiation (P = 0.01). When product-limit estimates were calculated after follow-up for up to 13 years (median follow-up, 56 months), the presence of distant metastases (P <0.001), neopterin (P <0.001), tumor size (P = 0.001), and lymph node status (P <0.01) were significant predictors of survival. By multivariate analysis, a combination of the variables presence of distant metastases (P <0. 001), neopterin (P <0.01), and lymph node status (P <0.05) was found to jointly predict survival. In lymph node-negative patients without distant metastases, the relative risk of death associated with increased neopterin concentrations was 2.5 compared with patients with neopterin concentrations within the reference interval. CONCLUSION: Urinary neopterin provides additional prognostic information in patients with breast cancer.

Increased neopterin concentrations in patients with cancer: indicator of oxidative stress?

In vitro, large amounts of neopterin are produced by human monocytes/macrophages upon stimulation with interferon-gamma. In vivo increased neopterin concentrations in human serum and urine indicate activation of cell-mediated (Th1-type) immune response, e.g., during virus infections, autoimmune diseases, allograft rejection and in certain types of malignancy. In various groups of patients with malignant diseases neopterin concentrations correlate to the stage of disease, and higher neopterin concentrations in serum, urine or ascitic fluid were shown to significantly predict worse prognosis regarding relapse and survival. The amounts of neopterin produced by activated monocytes/macrophages correlate with their capacity to release reactive oxygen species (ROS). With this background, neopterin concentrations in body fluids can be regarded as an indirect estimate of the degree of oxidative stress emerging during cell-mediated immune response. Moreover, recently neopterin was found itself to be capable of enhancing toxic effects induced by ROS. In vitro, neopterin derivatives were able to interfere with intracellular signal transduction pathways involved in, e.g., programmed cell death and the induction of proto-oncogene c-fos or nuclear factor-chi B. The data support the view that increased production of ROS--indicated by increased neopterin concentrations--could modulate the development, the proliferation and the survival of malignant cells.

Modulation of neopterin formation and tryptophan degradation by Th1- and Th2-derived cytokines in human monocytic cells.

In order to examine the regulatory effects of major Th1-derived cytokines, such as IL-12, and Th2 cytokines, IL-4 and IL-10, on the formation of neopterin and degradation of tryptophan, two metabolic pathways induced by interferon-gamma (IFN-gamma) in human monocytes/macrophages, we investigated the human monocytic cell line THP-1, primary human macrophages, and peripheral blood mononuclear cells (PBMC). Neopterin formation and tryptophan degradation were induced similarly by IFN-gamma in all three cell types investigated, but the effects of interleukins were different between THP-1, primary macrophages and PBMC. In PBMC, but not in THP-1 cells and primary macrophages, IL-12 was found to be additive to the effects of IFN-gamma to superinduce neopterin formation and tryptophan degradation. IL-4 and IL-10 reduced the effects of IFN-gamma on monocytic cells, and both cytokines were additively antagonistic to IFN-gamma in PBMC and THP-1 cells. Finally, on preincubation, but not on addition of IL-12, the effects of IL-4 and IL-10 on PBMC could be abrogated, whereas no such effect was seen in THP-1 cells. The results show that IL-12 up-regulates neopterin formation and tryptophan degradation by inducing additional IFN-gamma production by Th1 cells, while a direct effect of IL-12 on monocytes/macrophages appears to be absent. Similarly, IL-4 and IL-10 inhibit neopterin production and tryptophan degradation in PBMC by down-regulating Th1-type cytokine production and possibly also via direct deactivation of IFN-gamma effects towards monocytes/macrophages. The results clearly show how Th1 cell-mediated immunity may be up- or down-regulated by endogenous cytokine production.

Association between insulin resistance, body mass and neopterin concentrations.

Obesity is frequently associated with insulin resistance. Recently an important role of the cytokine tumor necrosis factor-alpha in mediating insulin resistance of obesity through its overexpression in fat tissue has been reported. In order to examine the relation of insulin resistance to obesity and to serum neopterin, as a parameter of immune activation, we studied 1234 otherwise healthy outpatients, who visited the physician's office for a medical health check-up. 7% showed elevated glucose concentrations, 34% elevated body mass indices. There were significant correlations between glucose concentrations and body mass indices and of the latter with serum neopterin concentrations. Neopterin concentrations were significantly higher in patients with elevated body mass indices (Mann-Whitney test, U = 131 358, p = 0.0003) and elevated glucose concentrations (Mann-Whitney test, U = 35 350 p =0.02). The data may indicate that moderate immune stimulation plays a role in the development of insulin resistance, and an influence of tumor necrosis factor-alpha seems to be probable.

Neopterin as a prognostic parameter in patients with squamous-cell carcinomas of the oral cavity.

Concentrations of neopterin, which is produced by human monocytes/macrophages upon stimulation by interferon-gamma, were measured in urine specimens in 23 patients with squamous-cell carcinoma of the oral cavity at diagnosis and in 12 treated patients with the same disease when recurrence of the tumor was recognized. Tumor histology and routine laboratory parameters were concomitantly determined. Urinary neopterin values showed no statistically significant correlation with tumor differentiation, tumor size or patient age, but they were significantly higher in patients with a recurrent tumor. Patients were followed for up to 4 years, and the ability of all variables to predict fatal outcome was assessed. In univariate analysis, only neopterin (p = 0.01) and the variable recurrent vs. first-diagnosed tumor were significant predictors of survival. In multivariate analysis, a combination of neopterin (p < 0.01) and the variable recurrent vs. first-diagnosed tumor (p = 0.06) was found to jointly predict survival. Thus, urinary neopterin concentrations provide valuable prognostic information in patients with squamous-cell carcinoma of the oral cavity.