Expression of putative leukemia stem cell targets in genetically-defined acute myeloid leukemia subtypes.

Although most acute myeloid leukemia (AML) patients achieve complete remissions, the majority still eventually relapse and die of their disease. Rare primitive leukemia cells, so-called leukemia stem cells (LSCs), represent one potential type of resistant cell subpopulation responsible for this dissociation between response and cure. Several LSC targets have been described, but there is limited evidence about their relative utility or that targeting any can prevent relapse. LSCs not only appear to be biologically heterogeneous, but the classic immunocompromised mouse transplantation model also has serious shortcomings as an LSC assay. Out data suggest that the most immature cell phenotype that can be identified within a patient's leukemia may be clinically relevant and represent the de facto LSC. Moreover, although phenotypically heterogeneous, these putative LSCs show consistent phenotypes within individual genetically defined groups. Using this LSC definition, we studied several previously described putative LSC targets, CD25, CD26, CD47, CD96, CD123, and CLL-1, and all were expressed across heterogeneous LSC phenotypes. In addition, with the exception of CD47, there was at most low expression of these targets on normal hematopoietic stem cells (HSCs). CD123 and CLL-1 demonstrated the greatest expression differences between putative LSCs and normal HSCs. Importantly, CD123 monoclonal antibodies were cytotoxic in vitro to putative LSCs from all AML subtypes, while showing limited to no toxicity against normal HSCs and hematopoietic progenitors. Since minimal residual disease appears to be a more homogeneous population of cells responsible for relapse, targeting CD123 in this setting may be most effective.

Quantitative and qualitative impairments in dendritic cell subsets of patients with ovarian or prostate cancer.

BACKGROUND: Dendritic cells (DCs) are the most efficient antigen-presenting cells, hence initiating a potent and cancer-specific immune response. This ability (mainly using monocyte-derived DCs) has been exploited in vaccination strategies for decades with limited clinical efficacy. Another alternative would be the use of conventional DCs (cDCs) of which at least three subsets circulate in human blood: cDC1s (CD141bright), cDC2s (CD1c+) and plasmacytoid DCs. Despite their paucity, technical advances may allow for their selection and clinical use. However, many assumptions concerning the DC subset biology depend on observations from mouse models, hindering their translational potential. In this study, we characterise human DCs in patients with ovarian cancer (OvC) or prostate cancer (PrC). PATIENTS AND METHODS: Whole blood samples from patients with OvC or PrC and healthy donors (HDs) were evaluated by flow cytometry for the phenotypic and functional characterisation of DC subsets. RESULTS: In both patient groups, the frequency of total CD141+ DCs was lower than that in HDs, but the cDC1 subset was only reduced in patients with OvC. CD141+ DCs showed a reduced response to the TLR3 agonist poly (I:C) in both groups of patients. An inverse correlation between the frequency of cDC1s and CA125, the OvC tumour burden marker, was observed. Consistently, high expression of CLEC9A in OvC tissue (The Cancer Genome Atlas data set) indicated a better overall survival. CONCLUSIONS: cDC1s are reduced in patients with OvC, and CD141+ DCs are quantitatively and qualitatively impaired in patients with OvC or PrC. CD141+ DC activation may predict functional impairment. The loss of cDC1s may be a bad prognostic factor for patients with OvC.

Distinguishing myelofibrosis from polycythemia vera and essential thrombocythemia: The utility of enumerating circulating stem cells with aberrant hMICL expression by flow cytometry.

INTRODUCTION: Diagnosing BCR-ABL negative myeloproliferative neoplasms (MPN) may be challenging due to overlapping features and lack of robust discriminatory parameters, especially between essential thrombocythemia (ET) and prefibrotic myelofibrosis (MF). Circulating immature hematopoietic cells are variably present in polycythemia vera (PV), ET, and MF. The C-type lectin hMICL is aberrantly expressed on hematopoietic stem cells in the majority of acute myeloid leukemia patients. However, the hMICL expression in MPN, having varying propensity of leukemic transformation, is unsettled. We hypothesized that enumeration of immature cells by flow cytometry (FCM) could be a discriminatory tool in MPN diagnostics. METHODS: By FCM, we quantified circulating stem cells with aberrant hMICL expression in 39 MPN patients, 10 age-matched controls, and in leukapheresis products from 10 patients with lymphoproliferative neoplasms. The utility of the FCM assay for discriminating MPN entities was evaluated by applying ROC curve analysis. RESULTS: While hMICL was absent in control samples, MF patients had significantly more hMICL+ stem cells (median 15.2%) than PV and ET (0.0%, P = .001 and 0.0%, P = .002, respectively). By ROC curve analysis, the presence of hMICL+ stem cells (>0 cells) in peripheral blood reliably discriminates MF from ET and PV with a sensitivity of 80% and a specificity of 97%. CONCLUSION: Enumeration of circulating hMICL+ stem cells by FCM can discriminate between MPN phenotypes and holds potential for monitoring disease evolution.

Uterine natural killer cell partnerships in early mouse decidua basalis.

The decidua basalis of developing mouse implantation sites is highly enriched in CD45+ leukocytes. In intact, syngeneically mated C57BL/6 decidua basalis examined at gestation day 8.5 by whole-mount in situ immunohistochemistry, leukocyte, but not trophoblast, conjugations were reported. Nothing is known regarding time course, frequency, composition, or importance of physiologic decidual CD45+ cell pairing. In this study, we confirmed the presence of anti-CD54+/anti-CD11a+ immune synapses in CD45+ decidual cell conjugates and characterized their cellular heterogeneity. Conjugated cell pairs were virtually absent before implantation (virgin and gestation days 3.5 and 4.5), were infrequent at gestation day 5.5, but involved 19% of all CD45+ cells by gestation day 8.5, then declined. By gestation day 8.5, almost all CD45+ cells coexpressed CD31, and 2 CD45+CD31+ cells composed most conjugates. Conjugation partners were defined for 2 nonoverlapping uterine natural killer cell subsets (Ly49C/I +/Dolichos biflorus agglutinin lectin- and Ly49C/I-/Dolichos biflorus agglutinin lectin+). Ly49C/I+ uterine natural killer cells were the major subset from before mating up to gestation day 6.5. At gestation day 5.5/6.5, uterine natural killer cell conjugates involving Ly49C/I + cells were more abundant. By gestation day 8.5/9.5, Dolichos biflorus agglutinin lectin+ uterine natural killer cells were the dominant subset with Dolichos biflorus agglutinin lectin+/Dolichos biflorus agglutinin lectin+ homologous conjugates and Dolichos biflorus agglutinin lectin+/Dolichos biflorus agglutinin lectin- heterologous conjugates dominating uterine natural killer cell pairings. At gestation day 6.5, both Ly49C/I+/CD45+ and Dolichos biflorus agglutinin lectin+/CD45+ heterologous conjugate pairs strongly engaged antigen-presenting cells (CD11c+, CD68+, or major histocompatibility complex class II+). By gestation day 8.5, dominant partners of Ly49C/I+/CD45+ and Dolichos biflorus agglutinin lectin+/CD45+ heterologous conjugates are T cells (CD8+ >CD4+). Heterologous conjugates that did not involve uterine natural killer cells occurred but did not suggest antigen presentation to T cells. These data identify gestation day 6.5-8.5 in the pregnant mouse as a critical window for leukocyte interactions that may establish immune regulation within implantation sites.

Evaluation of correlation of articular cartilage staining for DDR2 and proteoglycans with histological tissue damage and the results of radiographic assessment in patients with early stages of knee osteoarthritis.

OBJECTIVE: To determine, if staining of articular cartilage for proteoglycans (natural element of healthy and functioning cartilage) and discoidin domain receptor 2 (DDR2) (a protein associated with articular cartilage degradation) is correlated with histological tissue damage or radiographic assessment score in patients with early stages of knee osteoarthritis (OA). METHOD: 40 patients, with early stage OA were enrolled, from whom the biopsies for histological and immunohistochemical studies were obtained from edge of the femoral condyle during the arthroscopy. Semi-quantitative computer based analysis was used to evaluate the proportion of staining in histological sections. RESULTS: No correlation was shown between the proportion of tissue stained for DDR2 and histological score or the results of radiographic assessment of tibiofemoral (TF) joint. There was a negative correlation between the proportion of tissue stained for DDR2 and radiographic grade of patellofemoral (PF) OA (Spearman r=-0.34; 95% CI -0.60 to -0.02; P=0.03). No correlation was shown between the proportion of tissue stained for proteoglycans and histological score or the results of radiographic assessment of TF and PF joints. A negative correlation was found between proportion of tissue stained for DDR2 and proteoglycans. Spearman r=-0.43; 95% CI=-0.66 to -0.12; P=0.006. CONCLUSION: Production of DDR2 in articular cartilage could be related to early stages of OA, as it is significantly correlated to decrease of staining for cartilage proteoglycans. The role of production of DDR2 in cartilage may be decreased in stages, where higher grades of OA are detected on the radiographs.

A discrete population of IFN λ-expressing BDCA3hi dendritic cells is present in human thymus.

Human thymus contains two major subpopulations of dendritic cells (DCs), conventional DCs (cDCs) and plasmacytoid DCs (pDCs), which are mainly involved in central tolerance and also in protecting the thymus against infections. In blood and peripheral organs cDCs include the subpopulation of BDCA3(hi) DCs, considered as equivalents to mouse CD8α(+) DCs. In this study we describe in human thymus the presence of a discrete population of BDCA3(hi) DCs that, like their peripheral counterparts, express CD13, low-intermediate levels of CD11c, CLEC9A, high levels of XCR1, IRF8 and TLR3, and mostly lack the expression of CD11b, CD14 and TLR7. Thymic BDCA3(hi) DCs display immature features with a low expression of costimulatory molecules and HLA-DR, and a low allostimulatory capacity. Also, BDCA3(hi) DCs exhibit a strong response to TLR3 stimulation, producing high levels of interferon (IFN)-λ1 and CXCL10, which indicates that, similarly to thymic pDCs, BDCA3(hi) DCs can have an important role in thymus protection against viral infections.

CD141⁺ myeloid dendritic cells are enriched in healthy human liver.

BACKGROUND & AIMS: Extensive populations of liver immune cells detect and respond to homeostatic perturbation caused by damage, infection or malignancy. Dendritic cells (DCs) are central to these activities, governing the balance between tolerance and immunity. Most of our knowledge about human liver DCs is derived from studies on peritumoral tissue. Little is known about the phenotype and function of DCs, in particular the recently described CD141(+) subset, in healthy human liver and how this profile is altered in liver disease. METHODS: During liver transplantation, healthy donor and diseased explant livers were perfused and hepatic mononuclear cells isolated. Dendritic cell subset frequency and phenotype were characterised in liver perfusates by flow cytometry and the function of CD141(+) DCs was evaluated by mixed lymphocyte reactions (MLRs) and measuring cytokine secretion. RESULTS: Almost one third of liver CD11c(+) myeloid DCs (mDCs) expressed CD141 compared to <5% of circulating mDCs. Hepatic CD141(+) DCs demonstrated pro-inflammatory function in allogeneic MLRs, inducing T cell production of interferon gamma (IFN-γ) and interleukin (IL)-17. While CD123(+) plasmacytoid DCs (pDCs) and CD1c(+) mDCs were expanded in diseased liver perfusates, CD141(+) DCs were significantly depleted. Despite their depletion, CD141(+) DCs from explant livers produced markedly increased poly(I:C)-induced IFN lambda (IFN-λ) compared with donor DCs. CONCLUSIONS: Accumulation of CD141(+) DCs in healthy liver, which are significantly depleted in liver disease, suggests differential involvement of mDC subsets in liver immunity.

Increased tubulointerstitial recruitment of human CD141(hi) CLEC9A(+) and CD1c(+) myeloid dendritic cell subsets in renal fibrosis and chronic kidney disease.

Dendritic cells (DCs) play critical roles in immune-mediated kidney diseases. Little is known, however, about DC subsets in human chronic kidney disease, with previous studies restricted to a limited set of pathologies and to using immunohistochemical methods. In this study, we developed novel protocols for extracting renal DC subsets from diseased human kidneys and identified, enumerated, and phenotyped them by multicolor flow cytometry. We detected significantly greater numbers of total DCs as well as CD141(hi) and CD1c(+) myeloid DC (mDCs) subsets in diseased biopsies with interstitial fibrosis than diseased biopsies without fibrosis or healthy kidney tissue. In contrast, plasmacytoid DC numbers were significantly higher in the fibrotic group compared with healthy tissue only. Numbers of all DC subsets correlated with loss of kidney function, recorded as estimated glomerular filtration rate. CD141(hi) DCs expressed C-type lectin domain family 9 member A (CLEC9A), whereas the majority of CD1c(+) DCs lacked the expression of CD1a and DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), suggesting these mDC subsets may be circulating CD141(hi) and CD1c(+) blood DCs infiltrating kidney tissue. Our analysis revealed CLEC9A(+) and CD1c(+) cells were restricted to the tubulointerstitium. Notably, DC expression of the costimulatory and maturation molecule CD86 was significantly increased in both diseased cohorts compared with healthy tissue. Transforming growth factor-ß levels in dissociated tissue supernatants were significantly elevated in diseased biopsies with fibrosis compared with nonfibrotic biopsies, with mDCs identified as a major source of this profibrotic cytokine. Collectively, our data indicate that activated mDC subsets, likely recruited into the tubulointerstitium, are positioned to play a role in the development of fibrosis and, thus, progression to chronic kidney disease.

New generation of dendritic cell vaccines.

Dendritic cells (DC) play a pivotal role in the induction and regulation of immune responses, including the induction of cytotoxic T lymphocytes (CTL) responses. These are essential for the eradication of cancers and pathogens including HIV and malaria, for which there are currently no effective vaccines. New developments in our understanding of DC biology have identified the key DC subset responsible for CTL induction, which is now an attractive candidate to target for vaccination. These DC are characterized by expression of novel markers Clec9A and XCR1, and a specialized capacity to cross-present antigen (Ag) from tumors and pathogens that do not directly infect DC. New generation DC vaccines that specifically target the cross-presenting DC in vivo have already demonstrated potential in preclinical animal models but the challenge remains to translate these findings into clinically efficacous vaccines in man. This has been greatly facilitated by the recent identification of the equivalent Clec9A(+) XCR1(+) cross-presenting DC in human lymphoid tissues and peripheral tissues that are key sites for vaccination administration. These findings combined with further studies on DC subset biology have important implications for the design of new CTL-mediated vaccines.

Involvement of discoidin domain 1 receptor in recurrence of hepatocellular carcinoma by genome-wide analysis.

Hepatocellular carcinoma (HCC) is highly invasive with a high frequency of recurrence following surgery and poor prognosis. The underlying molecular mechanisms for HCC recurrence are not well understood. Here, we used microarray technology for genome-wide analysis to identify genes who may be involved in tumor recurrence. cDNA from HCC tumor tissues of patients with early recurrence (ER; n = 10) and patients whose HCC had not recurred ≥ 2 years postsurgery (nER; n = 10) was hybridized to the Affymetrix Human Geome U133 plus 2.0 whole-genome microarray. Gene clusters were identified and used for hierarchial clustering and principal component analysis. Genes with more than twofold change in expression between ER and nER groups were further analyzed. Expression levels of a subset of genes were validated using RT-PCR and immunohistochemistry. A total of 1,646 genes had significantly different expression between the ER and nER groups (P < 0.05) with 61 and 49 genes in the ER upregulated and downregulated for more than twofold in comparison with the nER group, respectively. The cellular functions of differentially expressed genes included cell adhesion, motility, cytoskeleton, transcription, metabolism, signal transduction, and apoptosis. The discoidin domain receptor 1 (DDR1) mRNA expression was significantly higher in the ER (3.36 ± 0.39) compared with the nER group (3.01 ± 0.49; P = 0.020). A greater proportion of liver tissue samples from ER versus nER patients had DDR1 protein expression (80.0 vs. 40.0 %, P = 0.022). Using microarray technology, we identified a number of genes whose expression differed between patients with recurrent HCC compared to those without. DD1 mRNA and protein levels were higher in patients with recurrent HCC, suggesting this gene maybe involved in tumor invasion and metastasis.

Age-dependent increase of discoidin domain receptor 2 and matrix metalloproteinase 13 expression in temporomandibular joint cartilage of type IX and type XI collagen-deficient mice.

Our previous studies demonstrated that mutations in type IX and type XI collagens in mice caused osteoarthritis (OA)-like changes in knee and temporomandibular (TM) joints. We also found that the overexpression of matrix metalloproteinase 13 (Mmp-13) was probably due to the up-regulation of a collagen receptor, discoidin domain receptor 2 (Ddr2), which was responsible for knee cartilage degeneration in mutant mice. The objective of our study was to determine whether the expression of Mmp-3, Mmp-13 and Ddr2 was increased in OA-like TM joints in mutant mice using immunohistochemistry. We found that the staining for Ddr2, Mmp-13 and Mmp-derived type II collagen fragments in tissue sections from 6-month-old mice was increased in TM joints of the mutant mice. In contrast, we found no difference in the staining for Mmp-3 amongst the two mutant mice and their wild-type littermates. We conclude that, similar to previous observations in knee joints, the overexpression of Ddr2 and Mmp-13 may be responsible for the OA-like change in TM joints in mutant mice.

Discoidin domain receptor 1 contributes to the survival of lung fibroblast in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF), characterized by fibroblast proliferation and accumulation of extracellular matrix, including collagen, is a chronic progressive disorder that results in lung remodeling and fibrosis. However, the cellular mechanisms that may make fibroblasts resistant to apoptosis have not been completely elucidated. Discoidin domain receptor 1 (DDR1), a receptor tyrosine kinase whose ligand is collagen, is expressed in vivo and contributes in vitro to leukocyte differentiation and nuclear factor (NF)-kappaB activation, which may play an important role in fibroblast survival. In this study, we examined in vivo and in vitro DDR1 expression and its role in cell survival using fibroblasts obtained from IPF and non-IPF patients. Immunohistochemically, fibroblasts present in fibroblastic foci expressed endogenous DDR1. The DDR1 expression level was significantly higher in fibroblasts from IPF patients, and the predominant isoform was DDR1b. In IPF patients, DDR1 activation in fibroblasts inhibited Fas ligand-induced apoptosis and resulted in NF-kappaB nuclear translocation. Suppression of DDR1 expression in fibroblasts by siRNA abolished these effects, and an NF-kappaB inhibitor abrogated the anti-apoptotic effect of DDR1 activation. We propose that DDR1 contributes to fibroblast survival in the tissue microenvironment of IPF and that DDR1 up-regulation may occur in other fibroproliferative lung diseases as well.

Expression of Discoidin Domain Receptor 2 (DDR2) in the developing heart.

Interactions between cells and the surrounding extracellular matrix are important for a number of developmental events. In the heart, cardiac fibroblasts produce the majority of extracellular matrix proteins, particularly collagen types I and III. Cells originating from the proepicardial organ migrate over the surface of the heart, invade the underlying myocardium and ultimately give rise to smooth muscle cells, fibroblasts, and coronary endothelium. Although integrin expression in the developing heart has been well characterized, the expression of Discoidin Domain Receptor 2 (DDR2) remains to be defined. Using confocal microscopy, the expression of DDR2 was examined at several points during cardiac development. Initially, DDR2 expression was detected on the epicardial surface of the heart and on endothelial and mesenchymal cells within the cardiac cushions. As development progressed, DDR2 expression increased at localized regions in the apex and atrioventricular sulcus, although this expression decreased from epicardial to endocardial surface. Eventually, DDR2 expression spanned the myocardial free wall and was detected within the septum. Not until postnatal development was DDR2 expression detected uniformly throughout the myocardium and this distribution was maintained in the adult heart. In summary, the data presented demonstrate that the distribution of DDR2-positive cells changes within the heart during development.

Altered fibroblast function following myocardial infarction.

Adequate wound healing and scar formation is an essential response to myocardial infarction (MI), and fibroblasts are primary cellular components regulating the process. How fibroblast functions are altered post-MI and to what extent these abnormalities persist in vitro is not well understood. Accordingly, we isolated myocardial fibroblasts from MI and non-MI (remote) regions at 7 days post-MI (n=35) and from the free wall and septum of unoperated control C57BL/6 mice (n=14). Proliferation was increased 182+/-28% in MI, but not in remote, fibroblasts compared with unoperated controls (P=0.01). Migration decreased 61+/-8%, adhesion to laminin decreased 79+/-8%, adhesion to collagen IV increased 196+/-27%, and collagen synthesis increased 169+/-24% in fibroblasts isolated from the MI region (all P<0.05). Migration, adhesion, and collagen synthesis changes were similar in remote fibroblasts, and the phenotypic differences were maintained through passage four. Transforming growth factor beta1 (TGFbeta1) is a bioactive molecule that has been shown to affect fibroblast function. Stimulation of unoperated control fibroblasts with 10 ng/ml TGFbeta(1) increased proliferation 137+/-7% (P=0.03 vs. unstimulated), increased adhesion to collagen IV 149+/-6% (P<0.01), and increased collagen I levels 187+/-10% (P=0.01). TGFbeta1 may, therefore, explain some of the changes in post-MI fibroblast phenotype. These data demonstrate for the first time region specific alterations in post-MI fibroblast biology that are maintained in vitro. Additionally, our model provides a novel in vitro template for examining the cellular mechanisms of wound healing and scar formation post-MI.

Membrane trafficking of angiotensin receptor type-1 and mechanochemical signal transduction in proximal tubule cells.

Cellular localization and trafficking of the major angiotensin receptor, AT1, was studied in mouse proximal tubule cell lines because angiotensin II concentrations in the luminal fluid of proximal tubules are greater than the K(d) of the receptor and would predict high turnover rates of the receptor. Mouse proximal tubule cells can exist in 2 polarized, differentiated states after confluence: a protoepithelium and a highly differentiated epithelium. The latter is distinguished by greater polarization of the microtubule cytoskeleton and collection of apical microtubule-dependent membrane proteins in condensed apical recycling endosomes (CARE) in proximity to the primary cilium. AT1, AT2, and the sodium hydrogen exchanger NHE3 are localized to CARE. With fluid movement, AT1 receptors externalize from CARE to the apical plasma membrane and allow luminal angiotensin II to initiate cell signaling. These data suggest that fluid movement controls receptor externalization and, hence, a model in which ciliary deflection results in transduction of a mechanical stimulus into the chemical signaling of the AT1 receptor.

Structural and functional characteristics of lung macro- and microvascular endothelial cell phenotypes.

Lung macro- and microvascular endothelial cells exhibit unique functional attributes, including signal transduction and barrier properties. We therefore sought to identify structural and functional features of endothelial cells that discriminate their phenotypes in the fully differentiated lung. Rat lung macro- (PAEC) and microvascular (PMVEC) endothelial cells each exhibited expression of typical markers. Screening for reactivity with nine different lectins revealed that Glycine max and Griffonia (Bandeiraea) simplicifolia preferentially bound microvascular endothelia whereas Helix pomatia preferentially bound macrovascular endothelia. Apposition between the apical plasmalemma and endoplasmic reticulum was closer in PAECs (8 nm) than in PMVECs (87 nm), implicating this coupling distance in the larger store operated calcium entry responses observed in macrovascular cells. PMVECs exhibited a faster growth rate than did PAECs and, once a growth program was initiated by serum, PMVECs sustained growth in the absence of serum. Thus, PAECs and PMVECs differ in their structure and function, even under similar environmental conditions.

Distribution of Endo180 receptor and ligand in developing articular cartilage.

OBJECTIVE: To investigate the expression of a novel member of the mannose receptor family, Endo180 (also known as uPARAP), and the distribution of Endo180 ligand(s) in the articular cartilage and growth plate of normal CBA mice and STR/ort mice, a well characterized model of spontaneous osteoarthritis. DESIGN: A polyclonal anti-Endo180 antibody was used to determine receptor expression. The Endo180 extracellular domain fused to a human immunoglobulin Fc tail was used to detect ligand. RESULTS: Endo180 receptor was strongly expressed in chondrocytes both in vitro and throughout the articular cartilage of young CBA and STR/ort mice. Expression decreased in older animals. In STR/ort mice with osteoarthritic lesions, no upregulation of Endo180 was detected. In the developing growth plate, Endo180 was expressed strongly by the proliferating chondrocytes. In contrast, Endo180 ligand was detected most strongly in hypertrophic zone of the growth plate and only at low levels in articular cartilage. In cultured chondrocytes, Endo180 was localized on the cell surface and in intracellular vesicles. CONCLUSION: Constitutively recycling endocytic receptors function to internalize ligand from the extracellular milieu and the ability of Endo180 to bind both glycosylated ligands and collagens suggests a role in extracellular matrix remodeling. Expression of Endo180 in articular cartilage chondrocytes of young, but not old, mice and the reciprocal expression of Endo180 and its ligands in the growth plate suggest that this receptor is involved in cartilage development but not in cartilage homeostasis. In addition, our data indicates that Endo180 does not appear to play a role in the development or progression of murine osteoarthritis.

The suppressive effect of bifidobacteria on Bacteroides vulgatus, a putative pathogenic microbe in inflammatory bowel disease.

Bacteroides, a predominant commensal bacteria in the gut, are thought to be responsible for the development of inflammatory bowel disease (IBD). In the present study, we examined whether or not bifidobacteria suppress B. vulgatus, a representative pathogenic Bacteroides species, in both the coculture system and the gnotobiotic murine model. As a result, Bifidobacterium infantis 1222 highly inhibited the growth of B. vulgatus in the coculture and also significantly suppressed the systemic antibody response raised by B. vulgatus colonizing the gut in gnotobiotic mice. Colonization of the mice by B. vulgatus increased the number of Peyer's patch (PP) cells bearing PNA (peanut agglutinin)+/anti-kappa+ phenotype, which represents plasma cell-like B cells. Moreover, treatment of those B. vulgatus-implanted mice with B. infantis 1222 abrogated such increase in the number of PNA+/anti-kappa+ cells. These results thus suggested that B. infantis 1222 protected the gut epithelial layer including the PP from being invaded by Bacteroides, thereby suppressing the systemic antibody response raised by Bacteroides.

Envelope glycosylation determined by lectins in microscopy sections of Acinetobacter venetianus induced by diesel fuel.

It was suggested in a previous study that cells of Acinetobacter venetianus VE-C3 adhere to diesel fuel by synthesizing a capsular polysaccharide containing glucose and/or mannose. To study the fine structure of cells and localization of bacterial polysaccharide in the presence of diesel fuel, two lectins were used: ConA, an agglutinin from Canavalia ensiformis specific for mannose and/or glucose residues, and PNA, an agglutinin from Arachis hypogaea, for terminal galactose residues. The lectins were conjugated with electron dense ferritin for transmission electron microscopy (TEM) and with fluorescein isothiocyanate (FITC) for scanning confocal laser microscopy (SCLM). Samples were prepared by freeze substitution, which allows glycosylation to be determined in situ in thin sections of specimens. The distribution of glycosylation was imaged with and without treatment of specimens with their specific hapten (glucose and galactose). The glycosylation activity produced a polysaccharide capsule. Emulsified diesel fuel nanodroplets were observed at the cell envelope perimeter. Fine structure of vesicles consisted of polysaccharide and diesel fuel nanodroplets. Lectin blotting analysis showed ConA-positive glycoprotein with an apparent molecular mass of 22 kDa in the outer membrane. Its production was induced by diesel fuel. This glycoprotein was probably responsible for bioemulsifying activity at the cell envelope. Several other glycoproteins were positive for PNA lectin, the main constituent migrating with an apparent molecular weight of 17.8 kDa. However, they were all constitutive and probably involved in cell biofilm formation at the oil surface.