Effects of glutamine, taurine and their association on inflammatory pathway markers in macrophages.

The immune system is essential for the control and elimination of infections, and macrophages are cells that act as important players in orchestrating the various parts of the inflammatory/immune response. Amino acids play important role in mediating functionality of the inflammatory response, especially mediating macrophages functions and cytokines production. We investigated the influence of glutamine, taurine and their association on the modulation of inflammatory pathway markers in macrophages. The RAW 264.7 macrophage cell line was cultivated in the presence of glutamine and taurine and proliferation rates, cell viability, cell cycle phases, IL-1α, IL-6, IL-10 and TNF-α as well as H2O2 production and the expression of the transcription factor, NFκB, and its inhibitor, IκBα, were evaluated. Our results showed an increase in viable cells and increased proliferation rates of cells treated with glutamine concentrations over 2 mM, as well as cells treated with both glutamine and taurine. The cell cycle showed a higher percentage of cells in the phases S, G2 and M when they were treated with 2 or 10 mM glutamine, or with glutamine and taurine in cells stimulated with lipopolysaccharide. The pNFκB/NFκB showed reduced ratio expression when cells were treated with 10 mM of glutamine or with glutamine in association with taurine. These conditions also resulted in reduced TNF-α, IL-1α and H2O2 production, and higher production of IL-10. These findings demonstrate that glutamine and taurine are able to modulate macrophages inflammatory pathways, and that taurine can potentiate the effects of glutamine, illustrating their immunomodulatory properties.

Prostaglandin F2α in vitro can affect basic inflammatory parameters of mesenchymal stem cells and slight modulating some of their immunomodulatory properties.

In the last decade, mesenchymal stem cells (MSCs) have been gaining attention due their ability to influence the function of other cells as well as modulate the inflammatory response. This occurs via their immunomodulatory functions,  acting through direct cell-cell interaction or by releasing a broad spectrum of bioactive factors such as cytokines and growth factors. In addition, prostaglandins are arachidonic acid metabolites that play a key role in the generation and modulation of the inflammatory response. Among the bioactive prostaglandins, PGF2α is able to stimulate cell proliferation as well as act to inhibit progenitor cell differentiation, but no information about this prostaglandin's action on the immunoregulatory function of MSCs has been reported. In this study we evaluate important aspects of the influence of PGF2α analog (17-phenyl-trinor PGF2α), which is a potent prostaglandin FP receptor agonist, on some mechanisms that control the main functions of MSCs. C3H10T1/2, a mesenchymal stem cell linage, was stimulated with PGF2α under inflammatory conditions trigged by LPS in order to investigate PGF2α inflammatory parameters as well as its ability to immunoregulate macrophages and lymphocytes. PGF2α has the ability to increase proliferation tax without altering the cell viability of LPS-stimulated MSCs, while also diminishing the phosphorylation of NFκB transcription factor leading to attenuation of IL-1ß and GM-CSF production. Additionally, MSC-s conditioned media from cells stimulated with PGF2α was able to increase the lymphocytes' IL-10 production. Overall, this study implied that PGF2α are able to modify some properties of MSCs.

Branched chain amino acids improve mesenchymal stem cell proliferation, reducing nuclear factor kappa B expression and modulating some inflammatory properties.

OBJECTIVES: The essential branched chain amino acids (BCAAs) valine, leucine, and isoleucine, are widely studied because of their effects on immunity and metabolism. Mesenchymal stem cells (MSCs) are a type of cell also studied due to their immunomodulatory properties. Since both BCAAs and MSCs have immunomodulatory capacity, the objective of this study was to evaluate the influence of BCAAs on some immunomodulatory aspects of MSCs. METHODS: MSCs were cultivated in BCAA-supplemented media to evaluate metabolic activity, including cell cycle, proliferative nuclear cell antigen, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, avian myelocytomatosis viral oncogene homolog, peroxisome proliferator activated receptor gamma, nuclear factor kappa B (NFкB), and signal transducers and activators of transcription 3 (STAT-3) expression. Additionally, some inflammatory mediators' synthesis, such as interleukin (IL) 1-beta, IL-10, granulocyte-macrophage colony-stimulating factor, transforming growth factor beta, nitric oxide, and prostaglandin E2, were also evaluated. RESULTS: Supplementation with BCAA led not only to increased MSC proliferation with more cells in the S, G2, and M cycle phases, but also to increased metabolic activity. BCAA supplementation also altered the immunomodulatory capacity of MSCs by decreasing the p-NFкB/NFкB and increasing the p-STAT-3/STAT-3 gene expression ratios, in addition to increasing synthesis of the antiinflammatory mediators transforming growth factor beta and prostaglandin E2. Finally, MSCs cultivated in BCAA-supplemented media was shown to decrease the IL-6 and tumor necrosis factor alpha production by macrophages. CONCLUSIONS: BCAA supplementation affected some immunoregulatory aspects of MSCs.

L-Glutamine in vitro Modulates some Immunomodulatory Properties of Bone Marrow Mesenchymal Stem Cells.

Glutamine (GLUT) is a nonessential amino acid that can become conditionally essential under stress conditions, being able to act in the modulation of the immune responses. Mesenchymal stem cells (MSCs) are known to their capability in the modulation of immune responses through cell-cell contact and by the secretion of soluble factors. Considering that GLUT is an immunonutrient and little is known about the influence of GLUT on the capability of MSCs to modulate immune cells, this work aims to investigate how variations in GLUT concentrations in vitro could affect some immunomodulatory properties of MSCs. In order to evaluate the effects of GLUT on MSCs immunomodulatory properties, cell proliferation rates, the expression of NFκB and STAT-3, and the production of IL-1ß, IL-6, IL-10, TGF-ß and TNF-α by MSCs were assessed. Based on our findings, GLUT at high doses (10 mM) augmented the proliferation of MSCs and modulated immune responses by decreasing levels of pro-inflammatory cytokines, such as IL-1ß and IL-6, and by increasing levels of anti-inflammatory cytokines IL-10 and TGF-ß. In addition, MSCs cultured in higher GLUT concentrations (10 mM) expressed lower levels of NF-κB and higher levels of STAT-3. Furthermore, conditioned media from MSCs cultured at higher GLUT concentrations (10 mM) reduced lymphocyte and macrophage proliferation, increased IL-10 production by both cells types, and decreased IFN-γ production by lymphocytes. Overall, this study showed that 10 mM of GLUT is able to modify immunomodulatory properties of MSCs.

The influence of protein malnutrition on biological and immunomodulatory aspects of bone marrow mesenchymal stem cells.

Tissues that require a great supply of nutrients and possess high metabolic demands, such as lympho-hemopoietics tissues, are the first to be affected by protein malnutrition (PM). Thus, PM directly affects hemopoiesis and the production and function of immune cells. Consequently, malnourished individuals are more susceptible to infections. Mesenchymal stem cells (MSCs) have immunomodulatory properties and are important in the formation of lympho-hemopoietic stroma. Since an adequate supply of nutrients is essential to sustain stroma formation, which is mainly constituted of MSCs and differentiated cells originated from them, this study investigated whether PM would influence some biological and immunomodulatory aspects of MSCs. Two-month-old Balb/c mice were divided into control and malnourished groups receiving normoproteic or hypoproteic diets, respectively (12% and 2% of protein) for 28 days. MSCs obtained from control (MSCct) and malnourished (MSCmaln) animals were characterized. In addition, the proliferation rate and cell cycle protein expression were determined, but no differences in these parameters were observed. In order to evaluate whether PM affects the immunomodulatory properties of MSCs, the expression of NFκB and STAT-3, and the production of IL-1α, IL-1ß, IL-6, IL-10, TGF-ß and TNF-α by MSCs were assessed. MSCmaln expressed lower levels of NF-κB and the production of IL-1ß, IL-6 and TGF-ß was significantly influenced by PM. Furthermore, MSCct and MSCmaln culture supernatants affected lymphocyte and macrophage proliferation. However, MSCmaln did not reduce the production of IFN-γ nor stimulate the production of IL-10 in lymphocytes in the same manner as observed in MSCct. Overall, this study implied that PM modifies immunosuppressive properties of MSCs.

Glutamine metabolism and its effects on immune response: molecular mechanism and gene expression

This article aims to review glutamine metabolism and its effects on the immune response. Selected topics are addressed, particularly the effect of glutamine on cell survival and proliferation, as well as its importance in some biochemical pathways. The impact of glutamine on muscle, intestine, and liver metabolism are described, and a special section about glutamine regulation of the immune response is included. In this context, the modulation of glutamine on relevant signaling pathways as nuclear factor kappa B (NF-kB), mitogen-activated protein kinases (MAPKs), and heat shock protein and the influence of this amino acid on cell migration and adhesion molecules are highlighted. Some important immune response pathways modulated by glutamine were described as its action incritically ill patients. In summary, this review describes some important actions of glutamine, and a range of reactions and modulatory effects in different organs, which may inform new therapeutic strategies. However, further studies are necessary to provide information about glutamine use, especially about situations in which it can be better used as well as fine-tuning dose and administration.