Modulation Of Adhesion Molecules Research Articles

Resveratrol attenuates microvascular inflammation in sepsis via SIRT-1-Induced modulation of adhesion molecules in ob/ob mice.

Obesity, a sirtuin-1 (SIRT-1) -deficient state, increases morbidity and resource utilization in critically ill patients. SIRT-1 deficiency increases microvascular inflammation and mortality in early sepsis. The objective of the study was to study the effect of resveratrol (RSV), a SIRT-1 activator, on microvascular inflammation in obese septic mice. ob/ob and C57Bl/6 (WT) mice were pretreated with RSV versus dimethyl sulfoxide (DMSO) (vehicle) prior to cecal ligation and puncture (sepsis). We studied (1) leukocyte/platelet adhesion, (2) E-selectin, ICAM-1, and SIRT-1 expression in small intestine, and (3) 7-day survival. A group of RSV-treated mice received SIRT-1 inhibitor (EX-527) with sepsis induction, and leukocyte/platelet adhesion and E-selectin/ICAM-1 expression were studied. We treated endothelial (HUVEC) cells with RSV to study E-selectin/ICAM-1 and p65-acetylation (AC-p65) in response to lipopolysaccharide (LPS). RSV treatment decreased leukocyte/platelet adhesion and E-selectin/ICAM-1 expression with increased SIRT-1 expression in septic ob/ob and WT mice, decreased E-selectin/ICAM-1 expression via increased SIRT-1 expression, and decreased AC-p65 expression in HUVEC. EX-527 abolished RSV-induced attenuation of microvascular inflammation in ob/ob septic mice. Finally, ob/ob mice in the sepsis+RSV group had significantly increased 7-day survival versus the sepsis+vehicle group. RSV increases SIRT-1 expression in ob/ob septic mice to reduce microvascular inflammation and improves survival.

Clopidogrel Significantly Lowers the Development of Atherosclerosis in ApoE-Deficient Mice in vivo

The anti-platelet drug clopidogrel has been shown to modulate adhesion molecule and cytokine expression, both playing an important role in the pathogenesis of atherosclerosis. The aim of this study was to investigate the impact of clopidogrel on the development and progression of atherosclerosis. ApoE−/− mice fed an atherogenic diet (cholesterol: 1 %) for 6 months received a daily dose of clopidogrel (1 mg/kg) by i.p. injection. Anti-platelet treatment was started immediately in one experimental group, and in another group clopidogrel was started 2 month after beginning of the atherogenic diet. Blood was analysed at days 30, 60 and 120 to monitor the lipid profile. After 6 months the aortic arch and brachiocephalic artery were analysed by Sudan IV staining for plaque size and by morphometry for luminal occlusion. Serum levels of various adhesion molecules were investigated by ELISA and the cellular infiltrate was analysed by immunofluorescence. After daily treatment with 1 mg/kg clopidogrel mice showed a significant reduction of atherosclerotic lesions in the thoracic aorta and within cross sections of the aortic arch [plaque formation 55.2 % (clopidogrel/start) vs. 76.5 % (untreated control) n = 8, P < 0.05]. After treatment with clopidogrel P-/E-selectin levels and cytokine levels of MCP-1 and PDGFβ were significantly reduced as compared to controls. The cellular infiltrate showed significantly reduced macrophage and T-cell infiltration in clopidogrel-treated animals. These results show that clopidogrel can effectively delay the development and progression of ‘de-novo’ atherosclerosis. However, once atherosclerotic lesions were already present, anti-platelet treatment alone did not result in reverse remodelling of these lesions.

Suitable in vitro Eimeria arloingi macromeront formation in host endothelial cells and modulation of adhesion molecule, cytokine and chemokine gene transcription.

Eimeria arloingi infections can cause severe haemorrhagic enteritis in young goat kids, thereby leading to high economic losses in goat industry worldwide. We aimed to isolate a new E. arloingi strain and establish a suitable in vitro culture system for the first merogony. E. arloingi oocysts were collected from naturally infected goat kids in the province of Alentejo, Portugal. For the maintenance of E. arloingi (strain A), kids kept under strict parasite-free conditions were orally infected with 10(3) sporulated oocysts each. Further, a new excystation protocol was successfully established to obtain viable sporozoites for further in vitro development in primary bovine umbilical vein endothelial cells (BUVEC). Overall, E. arloingi first merogony was successfully accomplished in BUVEC leading to macromeront formation (up to 150 μm) and the release of fully developed merozoites I stages. Moreover, host endothelial cell-parasite interactions were investigated in order to determine the extent of modulation carried out by E. arloingi in BUVEC during the first merogony. Gene transcription of adhesion molecules (E-selectin, P-selectin, VCAM-1, ICAM-1) was enhanced in the first hours post-infection (p.i.) in E. arloingi-infected BUVEC. BUVEC activation due to invasion was also shown by increased chemokine (CXCL8, CCL2, CCL5), cytokine (GM-CSF) and COX-2 gene transcription. The new E. arloingi (strain A) will be useful for better comprehension of early host innate immune reactions against this parasite in vitro/in vivo as well as to further our investigations in the complex Eimeria-host endothelial cell interactions.

Epithelial adhesion molecules and the regulation of intestinal homeostasis during neutrophil transepithelial migration

Epithelial adhesion molecules play essential roles in regulating cellular function and maintaining mucosal tissue homeostasis. Some form epithelial junctional complexes to provide structural support for epithelial monolayers and act as a selectively permeable barrier separating luminal contents from the surrounding tissue. Others serve as docking structures for invading viruses and bacteria, while also regulating the immune response. They can either obstruct or serve as footholds for the immune cells recruited to mucosal surfaces. Currently, it is well appreciated that adhesion molecules collectively serve as environmental cue sensors and trigger signaling events to regulate epithelial function through their association with the cell cytoskeleton and various intracellular adapter proteins. Immune cells, particularly neutrophils (PMN) during transepithelial migration (TEM), can modulate adhesion molecule expression, conformation, and distribution, significantly impacting epithelial function and tissue homeostasis. This review discusses the roles of key intestinal epithelial adhesion molecules in regulating PMN trafficking and outlines the potential consequences on epithelial function.

AB0023 In Vivo Effects of Epratuzumab, A Monoclonal Antibody Targeting Human CD22, on B Cell Function in Human CD22 Knock-In (HUKI) Mice

BackgroundEpratuzumab is a humanized monoclonal antibody that targets the B cell-specific protein CD22 and is currently in Phase 3 clinical trials in patients (pts) with systemic lupus erythematosus (SLE). Epratuzumab...

A Case of Life-Threatening Retinoic Acid Syndrome and Review of Literature

All-trans-retinoic acid represents a major progress that has made acute promyelocytic leukemia the most curable subtype of acute myeloid leukemia in adults. Although all-trans-retinoic acid is usually well tolerated, some patients develop the retinoic acid syndrome, characterized by unexplained fever, weight gain, respiratory distress, interstitial pulmonary infiltrates, pleural and pericardial effusions, episodic hypotension, and acute renal failure. Further studies of growth factor expression and modulation of adhesion molecules are warranted to provide further insights into the pathogenesis of the syndrome and may lead to its prevention.

The Impact of Obstructive Sleep Apnea and Nasal CPAP on Circulating Adiponectin Levels

Although obstructive sleep apnea syndrome (OSAS) is known to be an important risk factor for cardiovascular diseases, the mechanism behind this association has not been fully elucidated. Transendothelial migration of monocytes mediated by adhesion molecules is a crucial step in the pathogenesis of atherosclerosis. We investigated the effect of hypoxic stress on plasma adiponectin and tumor necrosis factor-α (TNF-α) levels and whether adiponectin and TNF-α modulate adhesion molecules in patients with OSAS. In 22 patients, plasma adiponectin and TNF-α levels and serum concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) were determined early in the morning after polysomnography and after nasal continuous positive airway pressure (nCPAP) treatment. Plasma adiponectin levels were inversely correlated with the apnea-hypopnea index (AHI) (r=-0.582, p<0.005) and % time in SpO2 <90% (r=-0.539, p<0.01) but not with the body mass index (BMI). TNF-α levels were positively correlated with the AHI (r=0.462, p<0.05) and BMI (r=0.452, p<0.05). Serum sICAM-1 levels were inversely correlated with plasma adiponectin levels (r=-0.476, p<0.05) but not with TNF-α levels. Although plasma TNF-α levels decreased after overnight nCPAP treatment (p<0.05), plasma adiponectin levels increased after long-term nCPAP (3months) treatment (p<0.02) in ten patients. Our findings suggest that reduced adiponectin and elevated TNF-α levels in plasma are associated with OSAS-induced hypoxic stress. Decreased adiponectin levels are associated with sICAM-1 levels.

Clinical Applications for Biomarkers of Acute and Chronic Graft-versus-Host Disease

Acute and chronic graft-versus-host disease (aGVHD, cGVHD) are serious complications of allogeneic hematopoietic cell transplantation. The complex pathophysiology of these disease processes is associated with immune system activation, the release of cytokines and chemokines, and alterations in cell populations. The blood levels of specific protein and cellular levels in patients with GVHD have correlated with the development, diagnosis, and prognosis of GVHD. Here, we review the most promising biomarkers for aGVHD and cGVHD with clinical relevance. The utility of GVHD biomarkers in clinical care of allogeneic hematopoietic cell transplantation recipients needs to be proven through clinical trials, and potential approaches to trial design are discussed.

Group V secreted phospholipase A2 contributes to LPS‐induced leukocyte recruitment

Secreted phospholipases A(2) (sPLA(2)s) are well known for their contribution in the biosynthesis of inflammatory eicosanoids. These enzymes also participate in the inflammatory process by regulating chemokine production and protein expression of adhesion molecules. The majority of sPLA(2) isoforms are up-regulated by proinflammatory stimuli such as bacterial lipopolysaccharide (LPS), which predominantly increases the expression of group V sPLA(2) (sPLA(2)-V). Furthermore, it has recently been shown that sPLA(2)-V is a critical messenger in the regulation of cell migration during allergic airway responsiveness. Herein, we investigated the effect of sPLA(2)-V on LPS-mediated leukocyte recruitment and its capacity to modulate adhesion molecule expression. We conducted our study in the murine air pouch model, using sPLA(2)-V null mice (sPLA(2)-V(-/-)) and control wild-type (WT) littermates. We observed that LPS (1 microg/ml)-mediated leukocyte emigration in sPLA(2)-V(-/-) was attenuated by 52% and 86% upon 6 and 12 h of treatment respectively, as compared to WT mice. In WT mice, treatment with the cell-permeable sPLA(2) inhibitor (12-epi-scalaradial; SLD) reduced LPS-mediated leukocyte recruitment by 67%, but had no additional inhibitory effect in sPLA(2)-V(-/-) mice. Protein analyses from the air pouch skin were carried out upon LPS-challenge, and the expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 were both significantly reduced in sPLA(2)-V(-/-) mice as compared to control WT mice. Together, our data demonstrate the role of sPLA(2)-V in LPS-induced ICAM-1 and VCAM-1 protein overexpression and leukocyte recruitment, supporting the contribution of sPLA(2)-V in the development of inflammatory innate immune responses.

Joint involvement in inflammatory bowel disease: managing inflammation outside the digestive system

Joint inflammation is present in approximately 30% of patients with inflammatory bowel disease. Peripheral arthritis can frequently be controlled by an optimal treatment of the gut inflammation in association with short-term use of NSAIDs. Recurrent inflammation requires the use of sulfasalazine. More therapy-resistant forms and axial arthropathy can be treated with anti-TNF drugs, predominantly infliximab and adalimumab. An intensified multidisciplinary approach in research and in the clinic may help to unravel the question of why common etiopathogenic mechanisms ultimately lead to different disease phenotypes. Animal models may help to identify the most promising therapeutic strategies including in the near future modulation of adhesion molecules, costimulatory molecules and the Th17 pathway.

GATA-2 and GATA-6 Involvement in Hydroxycarbamide Action On Endothelial Cells in Sickle Cell Disease.

Abstract 818Hydroxycarbamide (HC, or Hydroxyurea) is the only drug with a proven efficiency to treat patients affected by sickle cell disease (SCD), notably by decreasing vasoocclusive crisis (VOC) frequency, the hallmark of the disease. It is now admitted that abnormal red blood cells (RBC) carrying hemoglobin S exhibit increased adhesion to the vascular endothelium (VE) and that this inflammatory-strengthened adhesion plays a major role in VOC onset. Beyond its inconstant action on fetal hemoglobin stimulation, HC decreases adhesion between RBC and VE. Our laboratory and others have shown that HC modulates adhesion molecules expression on circulating RBC. We were the first to show that this action was reproducible in vitro on erythroid precursors and that HC also targets vascular endothelial cells (VEC) by modulating some adhesion molecules, pro-inflammatory cytokines and endothelin-1 (ET-1) expression. However, HC is a cytostatic agent that was firstly used to treat myeloproliferative disorders. Its mode of action is poorly understood and the potential deleterious effects of a life-long treatment are unknown. Our objective is then to decipher the sequence of events leading to target genes modulation to identify potential safer therapeutic targets and with an increased specificity of action. By conducting a network analysis of our microarray data obtained on VECs from the bone marrow microcirculation (TrHBMEC) treated or untreated with HC under basal or inflammatory conditions, we identified two candidate genes, namely transcription factors GATA-2 and GATA-6, as potential relevant intermediates in the HC-induced decreased endothelial expression of adhesion proteins and ET-1. GATA-2 and 6 expression was measured at the mRNA level by RQ-PCR and at the protein level by quantifying western blot signals in HC-treated TrHBMEC from 5 to 48h in basal conditions and in the presence of pro-inflammatory cytokines. In TrHBMEC, HC decreases mRNA levels of GATA-2 and GATA-6 time-dependently in basal and inflammatory states. Indeed, GATA-2 is significantly decreased from 16h-basal and 24h-inflammatory HC treatment with a maximal decrease at 48h (50%, p-value<0.0001 and 35%, p-value<0.0001 respectively). GATA-6 is significantly decreased from 16h-basal and 48h-inflammatory HC treatment, with a maximal decrease at 48h (42%, p-value = 0.0008 and 22%, p-value = 0.0004 respectively). Protein analyses performed by signals quantification following western blot did not show any GATA-6 protein modulation at 24h. However, at 48h, HC significantly decreases GATA-6 protein level in basal condition (44%, p-value = 0.0018) but in a less and non-significative extent in inflammatory condition. Studies of GATA-2 modulation at the protein level are still in process. Microarray experiments followed by RQ-PCR allowed us to point out and to confirm the mRNA downregulation of two GATA factors: GATA-2 and GATA-6 involved in the expression of previously-identified HC-modulated-adhesion genes. These results were validated at the protein level for GATA-6, for which a significant decrease at 48h in basal condition treatment was observed, in agreement with the observed HC effect on the GATA-6-dependent gene vWF (von Willebrand Factor). Functional HC effect on GATA2/6 binding to GATA-responsive elements is being currently tested by gel shift assays. These data will complete this study by the analysis of GATA activity modulation in response to HC treatment. Our results are consistent with our previous results concerning the HC effect on the endothelial expression of genes pertinent to SCD pathophysiology and known to contain GATA sites in their promoter: ET-1 and PECAM-1 (Platelet Endothelial Cell adhesion Molecule-1) for GATA-2, vWF for GATA-6 and VCAM-1 (Vascular Cell Adhesion Molecule-1) for both GATA-2 and GATA-6. It was proposed that HC acts through the NO-sGC-cGMP pathway; but mediators, notably transcription factors, between cGMP and final target genes are unknown. Our results suggest that GATA-2 and GATA-6 are mediators in the VEC HC response. Disclosures:No relevant conflicts of interest to declare.

Effect of Sulfasalazine on Renal Ischemia/Reperfusion Injury in Rats

Renal ischemia/reperfusion (I/R) occurs during shock and transplant procedures, greatly affecting outcome. A definitive treatment has not been found. One of the pathophysiological bases of renal I/R injury is the activation of the transcription factor nuclear factor-kappaB (NF-KappaB). We studied the effects of sulfasalazine (SFZ), a NF-kappaB inhibitor, over renal injury in a bilateral renal I/R model in rats. Ten male Wistar rats were subjected to bilateral renal I/R for 45 min followed by 24 h of reperfusion. Half of these received 100 mg/kg SFZ orally before the induction of I/R, while the others received only saline. Five rats served as sham-operated controls. At the end of the reperfusion period, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), blood urea nitrogen (BUN), P-selectin, tumor necrosis factor-alpha (TNF-alpha), intracellular adhesion molecule-1 (ICAM-1), and endothelin-1 (ET-1) concentrations were determined in serum, and renal samples were taken for histological evaluation. After renal I/R, AST, LDH, BUN, TNF-alpha, ICAM-1, and ET-1 serum levels were significantly increased, and tubules were severely damaged on histological analysis, compared to sham controls. SFZ treatment reduced the AST, LDH, BUN, TNF-alpha, and ET-1 elevations, as well as the tubular damage, induced by renal I/R. Serum ICAM-1 and P‐selectin were unchanged. These results show that SFZ has a protective effect over renal IR injury. The modulation of adhesion molecules probably does not play a part in these effects, but TNF-alpha and ET-1 modulation could be partly responsible for the effects we observed.

Adiponectin deficiency modulates adhesion molecules expression and cytokine production but does not affect disease severity in the transfer model of colitis

We investigated the effect of adiponectin (APN) deficiency in the CD4 +CD45RB high transfer model of colitis. Recombination activating gene (Rag)-1 knockout (KO) and Rag-1 APN KO mice receiving CD4 +CD45RB high cells developed colitis of comparable severity. Colonic mRNA expression of IL-6 and IL-17 was lower in Rag-1 APN KO mice compared to Rag-1 KO mice. Rag-1 APN KO and Rag-1 KO mice released comparable amounts of IL-6 from colon cultures, whereas release of IL-17 was higher in Rag-1 APN KO compared to Rag-1 KO mice. Expression of TNFα mRNA was comparable in Rag-1 KO and Rag-1 APN KO mice, but protein release was lower in Rag-1 APN KO mice compared to Rag-1 KO mice. Levels of IFNγ and IL-10 at mRNA and protein were comparable in Rag-1 KO and Rag-1 APN KO mice. Higher mRNA expression of VCAM-1 was observed in the colon of healthy APN KO compared to WT mice, while induction of colitis resulted in a comparable increase in VCAM-1 expression in Rag-1 KO and Rag-1 APN KO mice. In conclusion, although APN regulates expression of cytokines and adhesion molecules in the colon, this does not result in alteration of overall colitis severity in the CD4 +CD45RB high transfer model.

S1661 Adiponectin Deficiency Modulates Adhesion Molecules Expression and Cytokine Production But Does Not Affect Disease Severity in the Transfer Model of Colitis in Mice

S1661 Adiponectin Deficiency Modulates Adhesion Molecules Expression and Cytokine Production But Does Not Affect Disease Severity in the Transfer Model of Colitis in Mice

Decrease in adhesion molecules on polymorphonuclear leukocytes of patients with fibromyalgia

Fibromyalgia (FM) is a chronic widespread pain condition in highly stressed humans. Because stress is known to modulate adhesion molecule expression, we determined L: -selectin (CD62L) and beta(2)-integrin (CD11b/CD18) expression on the surface of polymorphonuclear leukocytes in 22 patients with FM. As compared to age and sex-matched healthy controls, FM patients showed a significantly decreased expression of CD62L (p < 0.01) and CD11b/CD18 (p < 0.05) on polymorphonuclear leukocytes. These changes might lower the rate of polymorphonuclear leukocyte migration to sites of inflammation and thereby compromise defense against infections and pain control.

Adhesion Molecules in Radiotherapy

Recent studies have documented changes in adhesion molecule expression and function after exposure to ionizing radiation. Adhesion molecules mediate cell-cell and cell-matrix interactions and are essential for a variety of physiological and pathological processes including maintenance of normal tissue integrity as well as tumor development and progression. Consequently, modulation of adhesion molecules by radiation may have a role in radiation-induced tumor control and normal tissue damage by interfering with cell signaling, radioresistance, metastasis, angiogenesis, carcinogenesis, immune response, inflammation and fibrosis. In addition, the interactions of radiation with adhesion molecules could have a major impact in developing new strategies to increase the efficacy of radiation therapy. Remarkable progress has been made in recent years to design targeted drug delivery to radiation-up-regulated adhesion molecules. Furthermore, the inhibition of adhesion, migration, invasion and angiogenesis by blocking adhesion receptors may represent a new therapeutic approach to improve tumor control and decrease radiation toxicity. This review is focused on current data concerning the mechanistic interactions of radiation with adhesion molecules and the possible clinical-pathological implications in radiotherapy.

Lipoproteins in inflammation and sepsis. I. Basic science

High-density lipoproteins (HDL) have been shown to bind and neutralize lipopolysaccharide (LPS) and are regarded as possible therapeutic agents for sepsis and conditions associated with local or systemic inflammation. However, in recent years, a multitude of possible immunomodulatory properties other than LPS neutralization have become evident. This review highlights the advances in the understanding of how HDL is protective in both in vitro and in vivo inflammatory settings, including the ability of HDL to modulate adhesion molecule expression, upregulate endothelial nitric oxide synthase and counteract oxidative stress. Also, the active components of HDL and the recent discovery of novel lipid modulators of inflammation are discussed.

Flt3-Ligand–Mobilized Peripheral Blood, but Not Flt3-Ligand–Expanded Bone Marrow, Facilitating Cells Promote Establishment of Chimerism and Tolerance

Abstract Facilitating cells (CD8+/TCR−) (FCs) enhance engraftment of limiting numbers of hematopoietic stem cells (HSCs). The primary component of FCs is precursor-plasmacytoid dendritic cells (p-preDCs), a tolerogenic cell expanded by Flt3-ligand (FL). In this study, we evaluated the function and composition of FL-expanded FCs. FL treatment resulted in a significant increase of FCs in bone marrow (BM) and peripheral blood (PB). When FL-expanded FCs were transplanted with c-Kit+/Sca-1+/Lin− (KSL) cells into allogeneic recipients, BM-FCs exhibited significantly impaired function whereas PB-FCs were potently functional. A significant upregulation of P-selectin expression and downregulation of VCAM-1 (vascular cell adhesion molecule 1) were present on FL-expanded PB-FCs compared with FL BM-FCs. Stromal cell–derived factor-1 (SDF-1), and CXCR4 transcripts were significantly increased in FL PB-FCs and decreased in FL BM-FCs. Supernatant from FL PB-FCs primed HSC migration to SDF-1, confirming production of the protein product. The FL PB-FCs contained a predominance of p-preDCs and natural killer (NK)–FCs, and NK-FCs were lacking in FL BM-FCs. The impaired function for BM-FCs was restored within 5 days after cessation of treatment. Taken together, these data suggest that FCs may enhance HSC homing and migration via the SDF-1/CXCR4 axis and adhesion molecule modulation. These findings may have implications in development of strategies for retaining function of ex vivo manipulated FCs and HSCs.

PANCREATITIC SERUM INDUCES MORPHOLOGICAL CHANGES IN MACROPHAGES

Background: We have previously demonstrated that pancreatitis modulates cellular adhesion molecule expression on blood leukocytes, including CD11a, CD49d and CD62L. These changes are likely due to the effect of factors, generated during acute pancreatitis and present in serum/plasma, on blood leukocytes. We investigated whether serum obtained from pancreatitic rats was able to induce phenotypic changes in macrophages compared with sham and normal controls. Methods: Acute pancreatitis was induced in Wistar rats by retrograde infusion of 4% sodium taurocholate (NaT) into the pancreatic duct. Sham rat controls consisted of open laparotomy with immediate closure. Serum from rats was obtained after 24 hr. Rat macrophages (NR8383 cell line) were cultured with various concentrations (1%, 5%, 10% or 20%) of serum from pancreatitic rats for 24 hr and then evaluated for morphologic changes (agglutination, adhesion, granule content) by light microscopy. Controls consisted of cells cultured with medium alone, normal saline or with serum from sham or normal rats. Cell recovery and viability were determined by trypan blue dye exclusion. Results: Pancreatitis was induced by instillation of 4% NaT and confirmed by histopathology. When rat macrophages were cultured in the presence of serum obtained from pancreatitic rats, phenotypic changes including increased agglutination/adhesion, and granule content were observed and were dose dependent (85% with 20% pancreatitic serum; p < 0.05, Student's t-test). These changes were not observed in any control groups. Cell recovery and viability were >90% in all conditions. Conclusions: Serum obtained from pancreatitic rats is able to induce morphologic changes in cultured macrophages, resembling an activated inflammatory state, which may result from adhesion molecule modulation and contribute to disease pathogenesis. Elucidation of contributory serum factors may provide novel approaches for immunotherapy in pancreatitis.

Flt3-Ligand-Mobilized Peripheral Blood, but Not Flt3-Ligand-Expanded Bone Marrow, Facilitating Cells Promote Establishment of Chimerism and Tolerance

Facilitating cells (CD8+/TCR-) (FCs) enhance engraftment of limiting numbers of hematopoietic stem cells (HSCs). The primary component of FCs is precursor-plasmacytoid dendritic cells (p-preDCs), a tolerogenic cell expanded by Flt3-ligand (FL). In this study, we evaluated the function and composition of FL-expanded FCs. FL treatment resulted in a significant increase of FCs in bone marrow (BM) and peripheral blood (PB). When FL-expanded FCs were transplanted with c-Kit+/Sca-1+/Lin- (KSL) cells into allogeneic recipients, BM-FCs exhibited significantly impaired function whereas PB-FCs were potently functional. A significant upregulation of P-selectin expression and downregulation of VCAM-1 (vascular cell adhesion molecule 1) were present on FL-expanded PB-FCs compared with FL BM-FCs. Stromal cell-derived factor-1 (SDF-1), and CXCR4 transcripts were significantly increased in FL PB-FCs and decreased in FL BM-FCs. Supernatant from FL PB-FCs primed HSC migration to SDF-1, confirming production of the protein product. The FL PB-FCs contained a predominance of p-preDCs and natural killer (NK)-FCs, and NK-FCs were lacking in FL BM-FCs. The impaired function for BM-FCs was restored within 5 days after cessation of treatment. Taken together, these data suggest that FCs may enhance HSC homing and migration via the SDF-1/CXCR4 axis and adhesion molecule modulation. These findings may have implications in development of strategies for retaining function of ex vivo manipulated FCs and HSCs.