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Anaemia occurs frequently in patients with heart failure and its current treatment lacks clear targets. Emerging evidence suggests that erythroid progenitor cell expansion is an integral part of physiological response to anaemia associated with chronic stress. Understanding the underlying mechanism may provide a novel approach to anaemia management. In this study, we aimed to examine a role for nitric oxide (NO) in the regulation of bone marrow erythroid progenitor response to chronic stress. For this purpose, adult male mice were subjected to 2 h daily restraint stress for 7 or 14 consecutive days. The role of NO was assessed by subcutaneous injection with NG-nitro-l-arginine methyl ester, 30 min prior to each restraint. Chronic exposure to stress resulted in significantly increased number of bone marrow erythroid progenitors, and blockade of NO biosynthesis prior to daily stress completely prevented stress-induced erythroid progenitor cell expansion. Furthermore, chronic stress exposure led to altered expression of neural, endothelial and inducible nitric oxide synthases (NOS) in the bone marrow, both on mRNA and protein level. Decreased expression of neural and endothelial NOS, as well as reduced expression of NF-kappaB/p65 in bone marrow nuclear cell fraction, was accompanied by elevated bone marrow expression of inducible NOS in chronically stressed animals. This is the first study to demonstrate a role for NO in adaptive response of erythroid progenitors to chronic stress. Targeting NO production may be beneficial to improve bone marrow dysfunction and reduced erythroid progenitor cell expansion in chronic heart failure patients.

Background/aim: The purpose of this study was to investigate proliferation and differentiation markers in colorectal adenocarcinoma and their correlation with clinicopathological factors. Materials and methods: Samples were collected from 38 patients with colorectal adenocarcinoma and 10 healthy controls. E-cadherin, carcinoembryonic antigen (mCEA), cyclin B1, vascular endothelial growth factor (VEGF), and erythropoietin (EPO) receptor (EPOR) were examined by immunohistochemistry; VEGF and EPO were examined by real-time PCR. Results: The tumor samples were mostly characterized by large dimension (pT3), moderate level of differentiation (G2), negative lymph node status (N0), and no metastasis. Cyclin B1 and VEGF gene and protein expressions were significantly higher in tumor tissues than in control tissues; E-cadherin expression was significantly decreased in tumor samples and in positive correlation with mCEA. EPO was almost undetectable in tumor tissues of colorectal adenocarcinoma. Significant positive correlation was detected between tumor size and cyclin B1, tumor grade, and lymph node status. Conclusion: Decreased expression of EPO, high levels of VEGF and cyclin B1 expression, predominant moderate tumor differentiation, absence of metastasis, and negative lymph node status may suggest low level of aggressiveness, better prognosis, and longer patient survival.

Macrophage migration inhibitory factor is a well-known proinflammatory cytokine that is released during systemic stress response. Although MIF can affect erythrocyte production, the role of this cytokine in stress-induced erythropoiesis is completely unknown. To extend our previous findings showing that chronic psychological stress stimulates extramedullary erythropoiesis, here we examined whether MIF is involved in the control of stress-induced erythropoietic response. Adult male C57BL/6 wild-type (WT) and MIF-KO (knock-out) mice were subjected to 2-h daily restraint stress for either 7 or 14 consecutive days. The number of erythroid progenitors and CD71/Ter119 profile of erythroid precursors were analyzed in the bone marrow and spleen. Additionally, MIF protein expression was assessed in WT mice. Our results demonstrated that chronic restraint stress enhanced the number of both erythroid progenitors and precursors in the spleen. Stress-induced increase in the number of splenic late erythroid progenitors as well as in the percentage of CD71(+)Ter119(+)-double-positive precursors was significantly more pronounced in MIF-KO mice compared to WT animals. Furthermore, repeatedly stressed WT animals demonstrated an augmented MIF expression in the spleen. Unlike the spleen, the bone marrow of chronically stressed WT mice exhibited less prominent changes in erythropoietic stress response and no significant alteration in MIF expression. In addition, MIF deficiency did not influence the bone marrow erythropoiesis in stressed animals. These findings suggest that MIF regulates extramedullary erythropoiesis by inhibiting an overexpansion of splenic immature erythroid cells during chronic stress and indicate a novel role for this cytokine under chronic stress conditions.

Interleukin 17 (IL-17) is a cytokine with pleiotropic effects associated with several inflammatory diseases. Although elevated levels of IL-17 have been described in inflammatory myopathies, its role in muscle remodeling and regeneration is still unknown. Excessive extracellular matrix degradation in skeletal muscle is an important pathological consequence of many diseases involving muscle wasting. In this study, the role of IL-17 on the expression of matrix metalloproteinase- (MMP-) 9 inmyoblast cells was investigated. The expression of MMP-9 after IL-17 treatment was analyzed in mouse myoblasts C2C12 cell line. The increase in MMP-9 production by IL-17 was concomitant with its capacity to inhibit myogenic differentiation of C2C12 cells. Doxycycline (Doxy) treatment protected the myogenic capacity of myoblasts from IL-17 inhibition and, moreover, increased myotubes hypertrophy. Doxy blocked the capacity of IL-17 to stimulateMMP-9 production by regulating IL-17-induced ERK1/2 MAPK activation. Our results imply that MMP-9 mediates IL-17's capacity to inhibit myoblast differentiation during inflammatory diseases and indicate that Doxy can modulate myoblast response to inflammatory induction by IL-17.

To evaluate whether the response of hematopoietic cells to interleukin-17 (IL-17) depends on the tissue microenvironment in which hematopoiesis occurs, the influence of recombinant mouse IL-17 on spleen hematopoietic cells and cytokine release was assessed in normal mice in vitro and in vivo. In vitro, IL-17 did not significantly affect the growth of granulocyte-macrophage (CFU-GM) and erythroid (BFU-E and CFU-E) derived colonies. A single injection of IL-17 in vivo exhibited stimulatory effects on hematopoietic cells from both granulocytic and erythroid lineages. The increased number of metamyelocytes 48 h after treatment imply to the IL-17-induced stimulation of granulopoiesis. The number of BFU-E was increased at 24 h, while the number of CFU-E increased 6 h and 24 h after treatment. Since the same treatment in the bone marrow decreased the number of CFU-E, it may be concluded that the local microenvironment plays an important role in IL-17-mediated effects on CFU-E. IL-17 increased the release of IL-6 both in vitro and in vivo, but showed tendency to suppress the constitutive secretion of IL-10 by spleen cells. Our results suggest the complexity of target cell response and interplay of secondary induced cytokines by IL-17 in different hematopoietic organs.

In order to gain more insight into mechanisms operating on the haematopoietic activity of the T-cell-derived cytokine, interleukin-17 (IL-17) and target cells that first respond to its action in vivo, the influence of a single intravenous injection of recombinant mouse IL-17 on bone marrow progenitors, further morphologically recognizable cells and peripheral blood cells was assessed in normal mice up to 72 h after treatment. Simultaneously, the release of IL-6, IL-10, IGF-I, IFN-gamma and NO by bone marrow cells was determined. Results showed that, in bone marrow, IL-17 did not affect granulocyte-macrophage (CFU-GM) progenitors, but induced a persistant increase in the number of morphologically recognizable proliferative granulocytes (PG) up to 48 h after treatment. The number of immature erythroid (BFU-E) progenitors was increased at 48 h, while the number of mature erythroid (CFU-E) progenitors was decreased up to 48 h. In peripheral blood, white blood cells were increased 6 h after treatment, mainly because of the increase in the number of lymphocytes. IL-17 also increased IL-6 release and NO production 6 h after administration. Additional in vitro assessment on bone marrow highly enriched Lin(-) progenitor cells, demonstrated a slightly enhancing effect of IL-17 on CFU-GM and no influence on BFU-E, suggesting the importance of bone marrow accessory cells and secondary induced cytokines for IL-17 mediated effects on progenitor cells. Taken together, these results demonstrate that in vivo IL-17 affects both granulocytic and erythroid lineages, with more mature haematopoietic progenitors responding first to its action. The opposite effects exerted on PG and CFU-E found at the same time indicate that IL-17, as a component of a regulatory network, is able to intervene in mechanisms that shift haematopoiesis from the erythroid to the granulocytic lineage.

The influence of recombinant human IL-17 on granulocyte-macrophage (CFU-GM) and erythroid (BFU-E and CFU-E) progenitors and the release of IL-1 alpha/beta, IL-6 and erythropoietin (EPO) was estimated in the bone marrow cells obtained from normal and sublethally irradiated mice. In normal mice IL-17 increased CFU-GM and BFU-E and reduced CFU-E derived colonies numbers and augmented release of IL-6 and EPO. In irradiated mice the effects of IL-17 on hematopoietic progenitors were lineage-dependent, as well as dependent on their stage of differentiation and the time after the irradiation. IL-17 had no major effects on CFU-GM on day 1 and 3, but decreased their number on day 2, while enhanced both BFU-E and CFU-E on day 1 and 2 after irradiation, whereas on day 3 its effect on erythroid progenitors was again as observed in normal mice. After irradiation, IL-17 increased the release of IL-1 alpha, IL-6 and EPO. The observed effects suggested the involvement of IL-17 in the regulation of hematopoiesis and indicated that its effects on both hematopoictic progenitors and cytokine release are dependent on the physiological/pathological status of the organism.

Stress evokes an integrated neuroendocrine response perturbing the homeostasis of different physiological systems. In contrast to well established physiologica linteractions between neuroendocrine and immune systems during chronic stress, there has been relatively little information on the effects of psychological stress on erythroid cells. Since stress-induced erythropoiesis occurs predominantly in the spleen, in the current study, we investigated the influence of chronic psychological stress on splenic erythroid progenitors and examined a role of glucocorticoid receptor (OR) in observed effect using a mouse model of restraint. The adult male mice were subjected to 2 hours daily restraint stress for 7 or 14 consecutive days and the role of OR in erythropoietic response to stress was assessed by pretreatment of mice with OR antagonist mifepristone 60 min prior to restraint. The results showed that chronic restraint stress induced an increase in spleen weight as well as in the cellularity of red pulp, as compared to controls. Furthermore, 7 and 14 days of restraint stress resulted in markedly increased number of both splenic early (BFU-E) and late (CFU-E) erythroid progenitors. Blockade of OR with mifepristone did not affect the number of BFU-E in stressed mice, but it completely abolished the effect of repeated psychological stress on CFU-E cells. Additionally, plasma corticosterone concentration was enhanced whereas the OR expression was significantly decreased within splenic red pulp after one and two weeks of stress exposure. Obtained findings suggest for the first time an indispensable role for OR in the expansion of CFU-E progenitors in the spleen under conditions of chronic psychological stress.

The influence of liposome structure on hematopoiesis in vivo was assessed in relation to the different contents and origins of phospholipids that make up their membrane structures. Changes within different hematopoietic cells and serum tumor necrosis factor alpha (TNF-alpha) levels were estimated up to 14 days following intravenous administration of liposomes made of either pure egg yolk phosphatidylcholine (L-EY) or a soybean phospholipid preparation (L-SB) into normal CBA mice. In peripheral blood, only transient changes within white blood cells were observed In bone marrow, a persistent decline in the number of mature granulocytes, monocytes, and lymphocytes was found. The changes within femoral granulocytic proliferative compartments in various stages of differentiation and a maturation compartment pointed out that, parallel with the depletion of the granulocyte-storage pool, stimulation of de novo production of granulocytic cells occurred. Although both types of tested liposomes induced similar cellular changes, only liposomes made of pure egg yolk phosphatidylcholine induced a transient increase in serum TNF-alpha levels.

There is little evidence for the role of granulocytes in the host defence against the protozoan parasite Toxoplasma gondii. Thus, the purpose of this study was to assess the involvement of granulocytes during acute murine infection with the parasite virulent RH strain. Since, all infected animals succumb to infection in a dose-dependent period of time, the effect of two parasite doses, 2x10(2) and 2x10(6), on granulocytis cell compartments in the bone marrow and peripheral blood up to 2 or 6 days post infection, respectively, was investigated. The data obtained revealed that granulocytic cells at various stages of differentiation and maturation were affected by T.gondii infection regardless of the dose applied. The observed oscillating changes in the number of cells in granulocytic proliferative and nonproliferative compartments imply that parallel with T.gondii-induced damage to granulocytic cells, a process of stimulated production of granulocytes occurred. Although some differences in the kinetics of cellular changes and in the extent of cell damage were found similar reactivity patterns of granulocytic cells were seen following infection with both doses. Our results demonstrated significant changes in granulopoiesis during T.gondii infection, suggesting a possible contribution of granulocytes to parasite control.

The multiple effects of interleukin-1 (IL-1) on hematopoietic cells are mainly documented in disturbed hematopoiesis, but its production and participation during constitutive hematopoiesis are still unproven, To assess the involvement of IL-1 in the regulation of steady-state hematopoiesis in vivo, we have investigated the consequences of IL-1 receptor blockade by recombinant human IL-1 receptor antagonist (rhIL-1Ra) in normal CBA/H mice treated with two i.p. injections of rhIL-1Ra (2 x 50 mu g/mouse) seventeen and two hours before sacrifice. The cellularity, the number of granulocyte-macrophage (CFU-GM), the number of erythroid (BFU-E) progenitor cells and the percentage of these cells in S phase of the cell cycle, as well as the morphologically recognizable cells in bone marrow were estimated, In peripheral blood, hematocrit, the number and differential count of nucleated cells, the number of erythrocytes and the percentage of reticulocytes were determined, IL-1Ra treatment significantly reduced the number of femoral CFU-GM and BFU-E, while all the other analyzed parameters were not different from the level obtained in control, non-treated animals. These findings show that a number of bone marrow IL-l-responsive cells were affected by the IL-1 receptor blockade, indicating that the expression of IL-1 receptors and endogenous IL-1 secretion occur as part of constitutive hematopoiesis.

Introduction Hydroxycarbamide, used in therapy of hemoglobinopathies, enhances nitric oxide (NO) production both in primary human umbilical vein endothelial cells (HUVECs) and human bone marrow endothelial cell line (TrHBMEC). Moreover, NO increases γ-globin and fetal hemoglobin levels in human erythroid progenitors. Objective In order to find out whether simple physiologic stimulation of NO production by components of hematopoietic microenvironment can increase γ-globin gene expression, the effects of NO-inducer bradykinin were examined in endothelial cells. Methods The study was performed in co-cultures of human erythroid progenitors, TrHBMEC and HUVECs by ozone-based chemiluminescent determination of NO and real-time quantitative RT-PCR. Results In accordance with previous reports, the endogenous factor bradykinin increased endothelial cell production of NO in a dose- and time-dependent manner (0.1-0.6 μM up to 30 minutes). This induction of NO in HUVECs and TrHBMEC by bradykinin was blocked by competitive inhibitors of NO synthase (NOS), demonstrating NOS-dependence. It has been shown that bradykinin significantly reduced endothelial NOS (eNOS) mRNA level and eNOS/s-actin ratio in HUVEC (by twofold). In addition, bradykinin failed to increase γ-globin mRNA expression in erythroid progenitors only, as well as in co-culture studies of erythroid progenitors with TrHBMEC and HUVEC after 24 hours of treatment. Furthermore, bradykinin did not induce γ/β globin ratio in erythroid progenitors in co-cultures with HUVEC. Conclusion Bradykinin mediated eNOS activation leads to short time and low NO production in endothelial cells, insufficient to induce γ-globin gene expression. These results emphasized the significance of elevated and extended NO production in augmentation of γ-globin gene expression., Uvod Hidroksikarbamid, koji se koristi u lečenju hemoglobinopatija, podstiče stvaranje azot-monoksida (NO) kako u primarnim ljudskim endotelnim ćelijama pupčane vene (HUVEC), tako i u izmenjenoj endotelnoj ćelijskoj liniji poreklom iz koštane srži (TrHBMEC). Štaviše, NO povećava stvaranje γ-globina i fetalnog hemoglobina u ljudskim progenitorima eritropoeze. Cilj rada Da bismo ustanovili da li jednostavna fiziološka stimulacija stvaranja NO od komponenti mikrosredine hematopoeze može povećati ekspresiju γ-globinskog gena, ispitivali smo efekte bradikinina, već poznatog stimulatora stvaranja NO. Metode rada Studija je izvedena u zajedničkim kulturama ljudskih progenitora eritropoeze sa TrHBMEC ili HUVEC i ispitivana hemiluminiscentnim merenjem NO posredstvom ozona, kao i primenom kvantitativnog RT-PCR na genskom nivou. Rezultati U skladu s prethodnim izveštajima, pokazali smo da endogeni faktor bradikinin povećava stvaranje NO u endotelnim ćelijama na dozno i vremenski zavisan način (0,1-0,6 μM do 30 minuta). Ovo stvaranje NO u HUVEC i TrHBMEC izazvano bradikininom blokirano je od strane konkurentskih inhibitora NO-sintaze (NOS), pokazujući NOS-zavisnost. Utvrdili smo da bradikinin značajno smanjuje stvaranje iRNK endotelne forme NOS (eNOS), kao i odnos eNOS i β-aktina u HUVEC (dvostruko manje). Pored toga, bradikinin ne povećava ekspresiju iRNK γ-globinskog gena ni u zasebnim progenitorima eritropoeze, niti u zajedničkim kulturama progenitora eritropoeze sa TrHBMEC ili HUVEC posle 24 sata tretmana. Bradikinin ne menja ni odnos γ i β globina u zajedničkim kulturama progenitora eritropoeze sa HUVEC. Zaključak Aktivacija eNO_ izazvana bradikininom dovodi do kratkog i malog povećanja NO u endotelnim ćelijama, što je nedovoljno da podstakne ekspresiju gena za γ-globin. Ovi rezultati naglašavaju važnost povećanog i produženog stvaranja NO radi stimulacije ekspresije γ-globina.

Mesenchymal stem cells (MSCs) were isolated from human periodontal ligament (hPDL-MSCs) and characterized by their morphology, clonogenic efficiency, proliferation and differentiation capabilities. hPDL-MSCs, derived from normal impacted third molars, possessed all of the properties of MSC, including clonogenic ability, high proliferation rate and multi-lineage (osteogenic, chondrogenic, adipogenic, myogenic) differentiation potential. Moreover, hPDL-MSCs expressed a typical MSC epitope profile, being positive for mesenchymal cell markers (CD44H, CD90, CD105, CD73, CD29, Stro-1, fibronectin, vimentin, alpha-SMA), and negative for hematopoietic stem cell markers (CD34, CD11b, CD45, Glycophorin-CD235a). Additionally, hPDL-MSCs, as primitive and highly multipotent cells, showed high expression of embryonic markers (Nanog, Sox2, SSEA4). The data obtained provided yet further proof that cells with mesenchymal properties can be obtained from periodontal ligament tissue. Although these cells should be further investigated to determine their clinical significance, hPDL-MSCs are believed to provide a renewable and promising cell source for new therapeutic strategies in the treatment of periodontal defects.

Adipose tissue is an attractive source of mesenchymal stem/stromal cells (MSCs) with potential applications in reconstructive plastic surgery and regenerative medicine. The aim of this study was to characterise human adipose tissue MSCs (ASCs) derived from healthy individuals and cancer patients and to compare their interactions with tumour cells. ASCs were isolated from adipose tissue of healthy donors, breast cancer-adjacent adipose tissue of breast cancer patients and tumour-adjacent adipose tissue of non-breast cancer patients. Their proliferation, differentiation, immunophenotype and gene expression were assessed and effects on the proliferation of human breast cancer cell line MCF-7 compared. ASCs from all sources exhibited similar morphology, proliferative and differentiation potential, showing the characteristic pattern of mesenchymal surface markers expression (CD90, CD105, CD44H, CD73) and the lack of HLA-DR and hematopoietic markers (CD11a, CD33, CD45, Glycophorin-CD235a), but uneven expression of CD34. ASCs also shared a common positive gene expression of HLA-DR, HLA-A, IL-6, TGF- and HIF-1, but were negative for HLA-G, while the expression levels of Cox-2 and IDO-1 varied. All ASCs significantly stimulated the proliferation of MCF-7 tumour cells in direct mixed co-cultures and transwell system, although their conditioned media displayed antiproliferative activity. Data obtained showed that ASCs with similar characteristics are easily isolated from various donors and sites of origin, although ASCs could both suppress and favour tumour cells growth, emphasising the importance of cellular context within the microenvironment and pointing to the significance of safety studies to exclude any potential clinical risk of their application in regenerative medicine.

Introduction. Mesenchymal stem cells (MSCs) are a promising tool for regenerative medicine, but due to the heterogeneity of their populations, different sources and isolation techniques, the characteristics defining MSCs are inconsistent. Objective. The aim of this study was to compare the characteristics of MSCs derived from two different human tissues: peripheral blood (PB-MSCs) and umbilical cord Wharton's Jelly (UC-MSCs). Methods. The PB-MSC and UC-MSC were isolated by adherence to plastic after gradient-density separation or an explant culture method, respectively, and compared regarding their morphology, clonogenic efficiency, proliferating rates, immunophenotype and differentiation potential. Results. MSCs derived from both sources exhibit similar morphology, proliferation capacity and multilineage (osteogenic, chondrogenic, adipogenic and myogenic) differentiation potential. Differences were observed in the clonogenic capacity and the immunophenotype, since UC-MSCs showed higher CFU-F (colony-forming units-fibroblastic) cloning efficiency, as well as higher embryonic markers (Nanog, Sox2, SSEA4) expression. When additional surface antigens were analyzed by flow cytometry (CD44, CD90, CD105, CD33, CD34, CD45, CD11b, CD235a) or immunofluorescent labeling (vimentin, STRO-1 and α-smooth muscle actin), most appeared to have similar epitope profiles irrespective of MSC source. Conclusion. The results obtained demonstrated that both MSCs represent good alternative sources of adult MSCs that could be used in cell therapy applications., Uvod. Mezenhimske matične ćelije (MMĆ) su posebno značajne za regenerativnu medicinu. S obzirom na heterogenost njihovih populacija, raznovrsnost izvora i tehnika izolacije, ne postoje jedinstvena obeležja koja određuju MMĆ. Cilj rada. Cilj ove studije bila je uporedna analiza bioloških karakteristika MMĆ izolovanih iz periferne krvi (PK-MMĆ) i Vartonove (Wharton) sluzi pupčane vrpce (VSP-MMĆ). Metode rada. PK-MMĆ i VSP-MMĆ su izolovane na osnovu osobine da prianjaju na plastičnu podlogu, a upoređivane su njihove morfološke odlike, klonogeni i proliferativni kapacitet, imunofenotip i potencijal diferencijacije. Rezultati. Dobijeni rezultati pokazali su da oba tipa MMĆ imaju slične morfološke osobine, sličan proliferativni kapacitet i multipotentni potencijal diferencijacije u ćelije različitih mezenhimskih tkiva (koštanog, masnog, hrskavičavog i mišićnog). Razlike su primećene u klonogenom kapacitetu i imunofenotipu, budući da su VSP-MMĆ ispoljile veći kapacitet za formiranje CFU-F (engl. colony-forming unit-fibroblasts), kao i veću ekspresiju markera tipičnih za embrionalne matične ćelije (Nanog, Sox2, SSEA4). Ispitivanje površinskih antigena tipičnih za MMĆ (CD44, CD90, CD105, CD33, CD34, CD45, CD11b, CD235a) protočnom citometrijom i imunofluorescentno obeležavanje dodatnih mezenhimskih markera (Vimentin, STRO-1 i alfa-aktina glatkih mišićnih ćelija) nije ukazalo na razlike u ekspresiji ovih markera. Zaključak. Oba tipa MMĆ su pogodan alternativni izvor adultnih MMĆ koje bi se mogle koristiti u ćelijskoj terapiji.

Mesenchymal stem cells (MSCs), beside regenerative potential, possess immunomodulatory properties and their use in managing immune-mediated diseases is intensively studied. We analyzed the effects of MSCs isolated from human adipose tissue (AT-MSCs), dental pulp (DP-MSCs), peripheral blood (PB-MSCs) and umbilical cord Wharton's jelly (UC-MSCs), on the proliferation of allogeneic peripheral blood mononuclear cells (PBMCs). While only AT-MSCs functioned as alloantigen presenting cells, proliferation of PBMCs in response to a phytohemagglutinin (PHA) and alloantigens in mixed lymphocytes reaction (MLR) was inhibited by all MSCs in a cell concentration-dependent manner. Conditioned medium (CM) derived from DP-MSCs, PB-MSCs and UC-MSCs, suppressed the baseline, PHA- and alloantigens-mediated proliferation of PBMC, whereas AT-MSCs-derived CM inhibited MLR, but failed to suppress the spontaneous and PHA-induced PBMCs proliferation. Differences between MSC types were observed in expression of genes related to immunomodulation, including human leukocyte antigens (HLA)-A, HLA-DR, HLA-G5, interleukin 6 (IL)-6, transforming growth factor (TGF)-beta, cyclooxygenase-2 (COX-2) and indoleamine 2,3-dioxygenase (IDO-1), under basal conditions, as well as in response to proinflammatory cytokines, interferon (IFN)-gamma and tumor necrosis factor alpha (TNF)-alpha. While AT-MSCs showed a positive constitutive expression of almost all tested genes that was augmented in response to IFN-gamma and TNF-alpha, only combined cytokine treatment increased HLA-A, COX2 and IL-6 mRNA expression in DP-MSCs and slightly stimulated the expression of HLA-G and TGF-beta in UC-MSCs. Although MSCs from different tissues showed similar potential to suppress proliferation of PBMCs, heterogeneity in the expression of genes related to immunomodulation emphasizes the importance of investigating the role of specific molecular mechanisms in the regulation of immunomodulatory activity of MSCs.

Interleukin-17 is Th17 cell cytokine implicated in regulation of hematopoiesis and inflammation. Besides promoting granulopoiesis, we have previously shown that IL-17 also affects erythropoiesis stimulating the development of early erythroid progenitors, BFU-E, but suppressing, at least partly via p38 MAPK, the growth of late stage erythroid progenitors, CFU-E. The aim of the present study was to investigate the involvement of other MAPKs, JNK and ERK1/2, as well as GATA transcription factors, in IL-17-mediated effects on murine bone marrow erythroid progenitors. Data obtained by use of specific MAPKs inhibitors indicated that MEK1/2-ERK1/2 MAPK signaling mediates IL-17-induced CFU-E inhibition, as well as that JNK and/or MEK1/2-ERK1/2 MAPKs activation underlies IL-17-induced stimulation of BFU-E growth. Furthermore, Western blot analyses demonstrated no effect on early hematopoiesis transcription factor, GATA-2, and enhanced expression level of erythroid-specific factor GATA-1 in murine bone marrow cells after IL-17 stimulation, which in light of previous reports that GATA-1 overexpression inhibits erythroid differentiation, could be related to IL-17-mediated inhibition of CFU-E growth. Although, no contribution for p38, JNK and ERK MAPKs in IL-17-induced GATA-1 expression was shown, data obtained using specific inhibitors pointed to the role of JNK and MEK1/2-ERK1/2 in GATA-1 downregulation. Overall, obtained data gave an insight into the mechanisms by which IL-17 exerts its effects on erythropoiesis, implying the involvement of JNK and ERK MAPKs, as well as GATA-1, in IL-17-regulated growth of erythroid progentors.

It has long been known that T cells have the potential to modulate hematopoietic response in different ways. More recently, the importance of interleukin (IL)-17-secreting Th17 cells in T-cell-mediated regulation of hematopoiesis was indicated by the line of evidence that IL-17 links T-cell function and hematopoiesis through stimulation of granulopoiesis and neutrophil trafficking. Furthermore, our data demonstrated that IL-17 also affects other cells of hematopoietic system, such as erythroid progenitors, as well as mesenchymal stem cells. In order to better understand the regulatory role of IL-17 in hematopoiesis, molecular mechanisms underlying the effects of IL-17 on hematopoietic and mesenchymal stem cells were also studied.

In the present study we have isolated and identified mesenchymal stem cells (MSCs) from the exfoliated deciduous teeth dental pulp (DP-MSCs), as plastic-adherent, spindle-shaped cells with a high proliferative potential. Immunophenotype analyses revealed that DP-MSCs were positive for mesenchymal cell markers (CD90, CD44, CD105, STRO-1, vimentin and α-SMA), and negative for hematopoietic stem cell markers (CD11b, CD33, CD34, CD45, CD235a). DPMSCs were also capable of differentiating into adipogenic, chondrogenic, myogenic and osteogenic lineages, fulfilling the functional criterion for their characterization. These results demonstrate that DP-MSCs offer a valuable, readily accessible source to obtain and store adult stem cells for future use.