Monitoring neopterin production in vitro is a sensitive way to detect immunomodulatory properties of compounds.
Inflammatory biomarker, neopterin, enlarges splenic mast-cell-progenitor
pool: prominent impairment of responses in age-related stromal cell-impairment
mouse SCI/SAM
Fukumoto
T, et al. Department of Anatomy, Nihon University School of Medicine, 30-1
Ohyaguchi-Kami-Machi, Tokyo, Japan
(Int Immunopharmacol 2006;6:1847-58)
Neopterin
is produced by monocytes and is a useful biomarker of inflammatory responses.
We found that neopterin enhances granulopoiesis, but suppresses B-lymphopoiesis
triggered by the positive and negative regulations of cytokines produced by
stromal cells in mice. In this study, neopterin was found to regulate mast cell
development, which was confirmed in the mouse model of senescent stromal-cell
impairment (SCI). In non-SCI mice (=less senescent stage of SCI mice),
neopterin decreased the number of colonies of IL-3-dependent mast-cell
progenitor cells (CFU-mast) from unfractionated bone-marrow cells, but not that
from the lineage-negative bone-marrow cell population without stromal cells in
a semisolid in vitro system. Neopterin increased the gene expression and
protein production of TGF-beta, a negative regulator of CFU-mast, in cultured
stromal cells, indicating that neopterin suppressed CFU-mast colony formation
by inducing TGF-beta in stromal cells. In contrast to this in vitro study, in
vivo treatment with neopterin did not significantly up-regulate TGF-beta. The
intravenous injection of neopterin into mice decreased the number of femoral
CFU-mast and the expression level of the gene for stem cell factor (SCF), a
positive regulator of CFU-mast, whereas the number of splenic CFU-mast and SCF
gene expression level increased. In SCI mice, the in vivo and in vitro
responses of mast cell development and cytokine gene expression level to
neopterin treatment were less marked than those in non-SCI mice. These results
suggest that, firstly, neopterin augments the splenic pool of CFU-mast by the
production of SCF, and secondly, such neopterin function becomes impaired
during senescence because of an impaired stromal-cell function, resulting in
the down-modulation of host-defense mechanisms.
Neopterin induces pro-atherothrombotic phenotype in human coronary
endothelial cells
Cirillo
P, et al. Division of Cardiology, University of Naples 'Federico II', Naples,
Italy. pcirillo@unina.it
(J Thromb Haemost 2006;4:2248-55)
BACKGROUND:
Inflammation plays a pivotal role in atherothrombosis. Recent data indicate
that serum levels of neopterin, a marker of inflammation and immune modulator
secreted by monocytes/macrophages, are elevated in patients with acute coronary
syndromes and seem to be a prognostic marker for major cardiovascular events.
The aim of the present study was to determine whether neopterin might affect
the thrombotic and atherosclerotic characteristics of human coronary artery
endothelial cells (HCAECs). METHODS AND RESULTS: In HCAECs, neopterin induced
TF-mRNA transcription as demonstrated by real time polymerase chain reaction
and expression of functionally active tissue factor (TF) as demonstrated by
procoagulant activity assay, and of cellular adhesion molecules (CAMs) as
demonstrated by FACS analysis, in a dose-dependent fashion. These neopterin
effects were prevented by lovastatin, a HMG-CoA reductase inhibitor.
Neopterin-induced TF and CAMs expression was mediated by oxygen free radicals
through the activation of the transcription factor, nuclear factor-kappa B
(NF-kappaB), as demonstrated by electrophoretic mobility shift assay and by
suppression of CAMs and TF expression by superoxide dismutase and by NF-kappaB
inhibitor, pyrrolidine-dithio-carbamate ammonium. CONCLUSIONS: These data
indicate that neopterin exerts direct effects on HCAECs by promoting CAMs and
TF expression and support the hypothesis that neopterin, besides representing a
marker of inflammation, might be an effector molecule able to induce a
pro-atherothrombotic phenotype in cells of the coronary circulation.
In
vitro effects of two extracts and two pure alkaloid preparations of Uncaria
tomentosa on peripheral blood mononuclear cells
Winkler C, et al. Institute of Medical Chemistry and Biochemistry,
University of Innsbruck, Innsbruck, Austria
(Planta
Med 2004; 70: 205-10)
In the traditional Peruvian medicine, hot aqueous extracts of Uncaria tomentosa have been used for the treatment of a wide range of health problems, particularly digestive complaints and arthritis. Some of the beneficial effects observed in patients suggest an immunomodulatory capacity of Uncaria tomentosa extracts. In this study, the effects of two extracts and two mixtures of tetracyclic and pentacyclic oxindole alkaloids of Uncaria tomentosa were investigated in freshly isolated human peripheral blood mononuclear cells (PBMC) stimulated with the mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A) in vitro. Neopterin production and tryptophan degradation were monitored in culture supernatants to determine the effects of the test substances on immunobiochemical pathways induced by interferon-gamma. Compared to unstimulated cells PHA and Con A increased the production of neopterin and degradation of tryptophan (p < 0.01). HCl and ethanol extracts and mixtures of alkaloids of Uncaria tomentosa inhibited both effects in a dose-dependent manner, the lowest effective concentrations of the extracts were 500 - 1000 microg/mL and of the alkaloid mixtures 100 - 175 microg/mL (p < 0.05 and < 0.01). With the highest concentrations of extracts and mixtures complete suppression of mitogen-induced neopterin production and tryptophan degradation was observed. These data demonstrate that Uncaria tomentosa extracts and mixtures of alkaloids modulate the immunobiochemical pathways induced by interferon-gamma. The findings imply a potential application of the extracts as immunoregulators and would be in line with observations in patients using these extracts.
Atorvastatin
suppresses interferon-gamma -induced neopterin formation and tryptophan
degradation in human peripheral blood mononuclear cells and in monocytic
cell lines.
Neurauter G, et al. Institute
of Medical Chemistry and Biochemistry, Leopold Franzens University,
Innsbruck, Austria
(Clin Exp Immunol 2003; 131: 264-7)
Inhibitors of 3-hydroxy-3methylglutaryl-co-enzyme A (HMG-CoA) reductase,
so-called statins, are used in medical practice because of their
lipid-lowering effect and to reduce the risk of coronary heart disease.
Recent findings indicate that statins also have anti-inflammatory
properties and can modulate the immune response. In vitro, we investigated
the effect of atorvastatin on the T cell/macrophage system in peripheral
blood mononuclear cells (PBMC) and in the human monocytic cell lines THP-1
and MonoMac6. We monitored neopterin production and tryptophan degradation
in PBMC after treatment with 10 micro m and 100 micro m atorvastatin in the
presence or absence of 100 U/ml IFN-gamma, 10 micro g/ml
phytohaemagglutinin (PHA) or 10 micro g/ml concanavalin A (ConA) and in
monocytic cell lines THP-1 and MonoMac6 with or without stimulation with
100 U/ml IFN-gamma or 10 ng/ml to 1 micro g/ml lipopolysaccharide (LPS). In
stimulated PBMC 100 micro m atorvastatin inhibited neopterin formation and
tryptophan degradation completely, whereas 10 micro m atorvastatin was only
partially effective. Also in monocytic cell lines THP-1 and MonoMac6,
atorvastatin was able to suppress IFN-gamma- and LPS-induced formation of
neopterin and degradation of tryptophan. Our data from PBMC agree well with
previous investigations that statins inhibit T cell activation within the
cellular immune response. In addition we demonstrate that atorvastatin
directly inhibits IFN-gamma-mediated pathways in monocytic cells,
suggesting that both immunoreactivity of T cells and of monocyte-derived
macrophages are down-regulated by this statin.
Modulation
of neopterin formation and tryptophan degradation by Th1- and Th2-derived
cytokines in human monocytic cells
Weiss G, et al. Department of Internal Medicine, University of
Innsbruck, Austria
(Clin Exp Immunol 1999; 116: 435-40)