Can neopterin be a useful immune biomarker for differentiating gastric intestinal metaplasia and gastric atrophy from non-atrophic non-metaplastic chronic gastritis? / ¿Puede la neopterina ser un biomarcador inmunológico para diferenciar la metaplasia intestinal gástrica y la atrofia gástrica de la gastritis crónica no atrófica y no metaplásica?

Introduction: Helicobacter pylori (H. pylori) is closely related to pre-neoplastic lesions such as gastric atrophy (GA), gastric intestinal metaplasia (GIM) and eventually gastric cancer (GC). The diagnosis of GIM and GA is usually based on endoscopic and histopathological features. Nowadays, there are no recognized good serological markers of GIM and GA. Neopterin is an important marker of cellular inflammation. In this study, we aimed to comparatively evaluate C-reactive protein (CRP) and neopterin levels in patients with GIM, GA and chronic gastritis, and to show the increased serum neopterin levels in GIM and GA according to non-atrophic and non-metaplastic chronic gastritis. Patients and methods: 98 patients with GIM and 68 patients with GA and 70 patients with non-atrophic non-metaplastic gastritis were included in the study. CRP and neopterin levels were assessed in patients and controls. Results: CRP and neopterin levels were significantly higher in patients with GIM and GA than in controls (p<0.05 and p<0.001, respectively). A multiple logistic regression analysis showed that high levels of serum neopterin were positively correlated with GIM and GA. According to the ROC curve analysis, the best cut-off value to differentiate between patients with GIM and/or GA from controls was ≥10.15nmol/l (p<0.001) for serum neopterin levels and ≥1.95mg/l (p<0.001) for serum CRP levels. Discussion: CRP and neopterin levels are significantly increased in GIM and GA. Neopterin may be a useful biomarker and diagnostic test for detecting GIM and GA in clinical practice. CRP levels may be helpful for this observation

Introducción: Helicobacter pylori (H. pylori) está estrechamente relacionado con lesiones preneoplásicas, como la atrofia gástrica (AG), metaplasia intestinal gástrica (MIG) y finalmente cáncer gástrico (CG). El diagnóstico de MIG y AG generalmente se basa en características endoscópicas e histopatológicas. Hoy día, no hay buenos marcadores serológicos reconocidos de MIG y AG. La neopterina es un marcador importante de inflamación celular. En este estudio, nuestro objetivo fue evaluar comparativamente la proteína C-reactiva (PCR) y los niveles de neopterina en pacientes con MIG, AG y gastritis crónica, y mostrar el aumento del nivel sérico de neopterina en MIG y AG sobre la base de gastritis crónica no atrófica y no metaplásica. Pacientes y métodos: Se incluyó en el estudio a 98 pacientes con MIG, 68 pacientes con AG y 70 pacientes con gastritis no atrófica y no metaplásica. Se evaluaron los niveles de PCR y neopterina en pacientes y controles. Resultados: Los niveles de PCR y neopterina fueron considerablemente más altos en los pacientes con MIG y AG que en los controles (p<0,05 y p<0,001, respectivamente). Un análisis de regresión logística múltiple mostró que el elevado nivel de neopterina sérica se correlacionó positivamente con MIG y AG. Según el análisis de la curva ROC, el mejor valor de corte para diferenciar entre pacientes con MIG y/o AG y controles fue ≥10,15nmol/l (p<0,001) para el nivel de neopterina sérica y ≥1,95mg/l (p<0,001) para el nivel de PCR en suero. Discusión: Los niveles de PCR y neopterina aumentan considerablemente en MIG y AG. La neopterina puede ser un biomarcador útil y una prueba de diagnóstico para detectar MIG y AG en el entorno clínico. Los niveles de PCR pueden ser útiles para esta observación

Neopterin acts as an endogenous cognitive enhancer.

Neopterin is found at increased levels in biological fluids from individuals with inflammatory disorders. The biological role of this pteridine remains undefined; however, due to its capacity to increase hemeoxygenase-1 content, it has been proposed as a protective agent during cellular stress. Therefore, we investigated the effects of neopterin on motor, emotional and memory functions. To address this question, neopterin (0.4 and/or 4pmol) was injected intracerebroventricularly before or after the training sessions of step-down inhibitory avoidance and fear conditioning tasks, respectively. Memory-related behaviors were assessed in Swiss and C57BL/6 mice, as well as in Wistar rats. Moreover, the putative effects of neopterin on motor and anxiety-related parameters were addressed in the open field and elevated plus-maze tasks. The effects of neopterin on cognitive performance were also investigated after intraperitoneal lipopolysaccharide (LPS) administration (0.33mg/kg) in interleukin-10 knockout mice (IL-10(-/-)). It was consistently observed across rodent species that neopterin facilitated aversive memory acquisition by increasing the latency to step-down in the inhibitory avoidance task. This effect was related to a reduced threshold to generate the hippocampal long-term potentiation (LTP) process, and reduced IL-6 brain levels after the LPS challenge. However, neopterin administration after acquisition did not alter the consolidation of fear memories, neither motor nor anxiety-related parameters. Altogether, neopterin facilitated cognitive processes, probably by inducing an antioxidant/anti-inflammatory state, and by facilitating LTP generation. To our knowledge, this is the first evidence showing the cognitive enhancer property of neopterin.

Mechanism of neopterin-induced myocardial dysfunction in the isolated perfused rat heart.

Neopterin is a sensitive marker for diseases involving increased activity of the cellular immune system in humans. Many studies, however, provide evidence for neopterin not only as a marker, but also for its characteristic effects. Recently, we were able to demonstrate a considerable influence of exogenous neopterin at a concentration of 100 mumol/l on cardiac performance in the Langendorff model of isolated perfused rat hearts. The present study was designed to investigate its possible mechanism. During co-infusion of neopterin at a concentration of 100 mumol/l with the unspecific nitric oxide synthase inhibitor N(G)-monomethyl-l-arginine monoacetate, the nitric oxide donor PAPA NONOate, the free radical scavenger N-acetylcysteine, or the pro-inflammatory cytokine tumor necrosis factor-alpha the effects on cardiac contractility parameters and coronary vascular resistance were studied in 67 male Sprague-Dawley rats. The temperature-controlled and pressure-constant Langendorff apparatus was used with retrograde perfusion of the aorta and a Krebs-Henseleit buffer. Neither the unspecific nitric oxide synthase inhibitor nor the nitric oxide donor excludes nitric oxide from playing a mechanistic role in our perfusion studies. Tumor necrosis factor-alpha was without any synergistic or antagonistic effects when co-treated with neopterin. N-acetylcysteine was most effective in abolishing neopterin-dependent effects on cardiac function. The negative effects of neopterin on cardiac performance might be due to an enhancement of oxidative stress by neopterin that can be attenuated by the antioxidant N-acetylcysteine. Neopterin has to be considered a pathogenic factor in the development of cardiac dysfunction in chronic disease states with high neopterin levels secondary to activation of the immune system.

Exogenous neopterin causes cardiac contractile dysfunction in the isolated perfused rat heart.

Neopterin is known in humans as a sensitive marker for diseases associated with increased activity of the cellular immune system. Recent studies report neopterin also to exhibit distinct effects: neopterin induces inducible nitric oxide synthase expression in rat vascular smooth muscle cells and activates translocation of nuclear factor- kappa B. Neopterin may also induce oxidative stress causing apoptotic cell death, or superinduce tumor necrosis factor- alpha -mediated apoptosis. Observing these effects in cell cultures, we were interested in possible consequences of neopterin on cardiac function in the isolated perfused rat heart. The influence of neopterin in three different concentrations (10 micromol/l, 50 micromol/l, 100 micromol/l) on cardiac contractility parameters and coronary vascular resistance were studied in 67 male Sprague-Dawley rats using the temperature-controlled and pressure-constant Langendorff apparatus with retrograde perfusion of the aorta with a Krebs-Henseleit buffer. Treatment with 100 micromol/l neopterin resulted in a significant decrease in coronary flow and cardiac contractility. Coronary flow decreased from 15.2 to 9.5 ml/min (P=0.002), left ventricular pressure from 80 to 52 mmHg (P=0. 002), rate of pressure fall from 1605 to 923 mmHg/s (P=0.001) and rate of pressure rise from 2862 to 1709 mmHg/s (P=0.001). Concentrations lower than 100 micromol/l neopterin had no significant effect on cardiac function. Our study demonstrates a considerable influence of exogenous neopterin on cardiac performance in the Langendorff model of isolated perfused rat hearts. This has to be considered a potential pathogenic factor of cardiac disturbances in diseases in which high concentrations of neopterin are released due to immune activation. At present the exact mechanism remains unclear.