Rosuvastatin promotes the differentiation of peripheral blood monocytes into M2 macrophages in patients with atherosclerosis by activating PPAR-γ

OBJECTIVE

To evaluate M2 marker changes in human circulating monocytes before and after rosuvastatin treatment, and to investigate the effects of rosuvastatin on the differentiation of monocytes into M2 macrophages by activating peroxisome proliferator-activated receptor-γ (PPAR-γ).

PATIENTS AND METHODS

A total of 20 patients was administrated with rosuvastatin. The human peripheral blood mononuclear cells (PBMCs) were extracted by Ficoll-Hypaque density gradient centrifugation method. PPAR-γ, CD206 and CD163 mRNA levels were detected by Real-time polymerase chain reaction (RT-PCR). The total content of tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), PPAR-γ, extracellular signal-regulated kinase (ERK) and p38 Mitogen-activated protein kinase (MAPK) and the contents of phosphorylated ERK and p38 MAPK were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The expression levels of CD206, Interleukin 10 (IL-10), and chemokine (C-C motif) ligand 18 (CCL18) were significantly improved by rosuvastatin. The expression level of PPAR-γ in circulating monocytes was also distinctly up-regulated through the treatment with rosuvastatin. After rosuvastatin therapy, PPAR-γ mRNA expression was unceasingly increased with time prolonging. The tendency of mRNA level of aP2 was the same as that of PPAR-γ. In vitro experiments indicated that in M2 macrophages, rosuvastatin could enhance the decrease of CD163 expression level induced by interleukin 4 (IL-4). M1 macrophages cultured by supernatant that was used to culture M2 macrophages could significantly inhibit TNF-α and MCP-1 expressions. Rosuvastatin could remarkably induce the phosphorylation of p38 MAPK, but the effect on ERK1/2 was not obvious.

CONCLUSIONS

Our results confirmed expressions of M2 markers in human circulating peripheral blood monocytes after rosuvastatin therapy. Both in vivo and in vitro experiments proved that rosuvastatin can induce the expression and activation of PPAR-γ in human monocytes, resulting in the differentiation of monocytes into M2 macrophages.

Role for microglia in sex differences after ischemic stroke: importance of M2

Inflammation plays a critical role in the pathogenesis of ischemic stroke. This process depends, in part, upon proinflammatory factors released by activated resident central nervous system (CNS) microglia (MG). Previous studies demonstrated that transfer of IL-10(+) B-cells reduced infarct volumes in male C57BL/6 J recipient mice when given 24 h prior to or therapeutically at 4 or 24 h after experimental stroke induced by 60 min middle cerebral artery occlusion (MCAO). The present study assesses possible sex differences in immunoregulation by IL-10(+) B-cells on primary male vs. female MG cultured from naïve and ischemic stroke-induced mice. Thus, MG cultures were treated with recombinant (r)IL-10, rIL-4 or IL-10(+) B-cells after lipopolysaccharide (LPS) activation and evaluated by flow cytometry for production of proinflammatory and anti-inflammatory factors. We found that IL-10(+) B-cells significantly reduced MG production of TNF-α, IL-1β and CCL3 post-MCAO and increased their expression of the anti-inflammatory M2 marker, CD206, by cell-cell interactions. Moreover, MG from female vs. male mice had higher expression of IL-4 and IL-10 receptors and increased production of IL-4, especially after treatment with IL-10(+) B-cells. These findings indicate that IL-10-producing B-cells play a crucial role in regulating MG activation, proinflammatory cytokine release and M2 phenotype induction, post-MCAO, with heightened sensitivity of female MG to IL-4 and IL-10. This study, coupled with our previous demonstration of increased numbers of transferred IL-10(+) B-cells in the ischemic hemisphere, provide a mechanistic basis for local regulation by secreted IL-10 and IL-4 as well as direct B-cell/MG interactions that promote M2-MG.

Expression and crystallographic studies of the ligand-binding region of the human endocytic collagen receptor uPARAP

Urokinase plasminogen activator receptor-associated protein (uPARAP) is an endocytic receptor that internalizes collagen for lysosomal degradation and plays an important role in matrix remodelling. Previous recombinant protein production of uPARAP in Pichia pastoris generated protein with highly heterogeneous glycans that was prone to proteolytic degradation, resulting in highly twinned crystals. In this study, the uPARAP ligand-binding region was expressed in stably transfected Drosophila S2 insect cells. The recombinant protein was homogeneous after purification by metal-affinity and anion-exchange chromatography. Crystals were obtained at two different pH values (5.3 and 7.4) and diffracted to 2.44 and 3.13 Å resolution, respectively. A model of the ligand-binding region of uPARAP was obtained by molecular replacement combined with autobuilding. As the first multidomain crystal structure of the mannose receptor family, structural characterization of the uPARAP ligand-binding region will provide insight into the pH-induced conformational rearrangements of the mannose receptor family.

Galectin-2 induces a proinflammatory, anti-arteriogenic phenotype in monocytes and macrophages

Galectin-2 is a monocyte-expressed carbohydrate-binding lectin, for which increased expression is genetically determined and associated with decreased collateral arteriogenesis in obstructive coronary artery disease patients. The inhibiting effect of galectin-2 on arteriogenesis was confirmed in vivo, but the mechanism is largely unknown. In this study we aimed to explore the effects of galectin-2 on monocyte/macrophage phenotype in vitro and vivo, and to identify the receptor by which galectin-2 exerts these effects. We now show that the binding of galectin-2 to different circulating human monocyte subsets is dependent on monocyte surface expression levels of CD14. The high affinity binding is blocked by an anti-CD14 antibody but not by carbohydrates, indicating a specific protein-protein interaction. Galectin-2 binding to human monocytes modulated their transcriptome by inducing proinflammatory cytokines and inhibiting pro-arteriogenic factors, while attenuating monocyte migration. Using specific knock-out mice, we show that galectin-2 acts through the CD14/toll-like receptor (TLR)-4 pathway. Furthermore, galectin-2 skews human macrophages to a M1-like proinflammatory phenotype, characterized by a reduced motility and expression of an anti-arteriogenic cytokine/growth factor repertoire. This is accompanied by a switch in surface protein expression to CD40-high and CD206-low (M1). In a murine model we show that galectin-2 administration, known to attenuate arteriogenesis, leads to increased numbers of CD40-positive (M1) and reduced numbers of CD206-positive (M2) macrophages surrounding actively remodeling collateral arteries. In conclusion galectin-2 is the first endogenous CD14/TLR4 ligand that induces a proinflammatory, non-arteriogenic phenotype in monocytes/macrophages. Interference with CD14-Galectin-2 interaction may provide a new intervention strategy to stimulate growth of collateral arteries in genetically compromised cardiovascular patients.

Human DNA methyltransferase gene-transformed yeasts display an inducible flocculation inhibited by 5-aza-2'-deoxycytidine

Mammalian DNA methyltransferases (DNMTs) play an important role in establishing and maintaining the proper regulation of epigenetic information. However, it remains unclear whether mammalian DNMTs can be functionally expressed in yeasts, which probably lack endogenous DNMTs. We cotransformed the budding yeast Saccharomyces cerevisiae with the human DNMT1 gene, which encodes a methylation maintenance enzyme, and the DNMT3A/3B genes, which encode de novo methylation enzymes, in an expression vector also containing the GAL1 promoter, which is induced by galactose, and examined the effects of the DNMT inhibitor 5-aza-2'-deoxycytidine (5AZ) on cell growth. Transformed yeast strains grown in galactose- and glucose-containing media showed growth inhibition, and their growth rate was unaffected by 5AZ. Conversely, 5AZ, but not 2'-deoxycytidine, dose-dependently interfered with the flocculation exhibited by DNMT-gene transformants grown in glucose-containing medium. Further investigation of the properties of this flocculation indicated that it may be dependent on the expression of a Flocculin-encoding gene, FLO1. Taken together, these findings suggest that DNMT-gene transformed yeast strains functionally express these enzymes and represent a useful tool for in vivo screening for DNMT inhibitors.

Agents that increase AAM differentiation blunt RSV-mediated lung pathology

RSV is the most significant cause of serious lower respiratory tract infection in infants and young children worldwide. There is currently no vaccine for the virus, and antiviral therapy (e.g., ribavirin) has shown no efficacy against the disease. We reported that alternatively activated macrophages (AAMs) mediate resolution of RSV-induced pathology. AAM differentiation requires macrophage-derived IL-4 and -13, autocrine/paracrine signaling through the type I IL-4 receptor, and STAT6 activation. Based on these findings, we reasoned that it would be possible to intervene therapeutically in RSV disease by increasing AAM differentiation, thereby decreasing lung pathology. Mice treated with the IL-4/anti-IL-4 immune complexes, shown previously to sustain levels of circulating IL-4, increased the RSV-induced AAM markers arginase-1 and mannose receptor and decreased the lung pathology. Induction of PPARγ, shown to play a role in AAM development, by the PPARγ agonist rosiglitazone or treatment of mice with the macrolide antibiotic AZM, also reported to skew macrophage differentiation to an AAM phenotype, increased the AAM markers and mitigated RSV-induced lung pathology. Collectively, our data suggest that therapeutic manipulation of macrophage differentiation to enhance the AAM phenotype is a viable approach for ameliorating RSV-induced disease.

Role of the exogenous HCV core protein in the interaction of human hepatocyte proliferation and macrophage sub-populations

BACKGROUND

The core protein of hepatitis C virus (HCV) is found in the cytoplasm and nuclei of infected cells, including hepatocytes and other cells in the liver. The core protein could be secreted as well. Resident liver macrophages are dependent on the tissue micro-environment and external stimuli to differentiate M1 and M2 hypotypes with distinct functions, and increased expression of the nuclear transcription factor STAT3 was seen in M2-polarized macrophages. In contrast to proinflammatory M1 macrophages, M2 macrophages serve beneficial roles in chronic inflammation, immunosuppression, and tumorigenesis.

METHODS

Monocyte-derived human macrophage line (mTHP-1) was treated with the exogenous HCV core protein. Next, the mTHP-1 culture supernatant or cell pellets were added to culture media of normal human liver cell line (L02).

RESULTS

Only the culture supernatant stimulated L02 cells proliferation, which was associated with phosphorylated ERK expression. Core protein activated mTHP-1 cells showed enhanced pro- and anti-inflammatory cytokines secretion, which was accompanied by high expression of phosphorylated NF-κB105 and NF-κB65. However, phosphorylated STAT1, and STAT3, which are normally associated with M1 and M2 macrophage polarization, and cell surface expression of CD206, CD14, CD16, and CD86, were unaltered. A transwell co-culture system showed that only in mTHP-1 co-cultured with L02 in the presence of exogenous core protein, were higher levels of phosphorylated STAT3 and CD206 seen.

CONCLUSIONS

We showed L02 cells proliferation was accelerated by the culture supernatant of mTHP-1 cells treated with the exogenous HCV core protein. The exogenous core protein mediated the interaction between macrophages and hepatocytes in co-culture, which enhanced the expression of phosphorylated STAT3 and CD206 in macrophages.

Number of Langerhans cells is decreased in premalignant keratosis and skin cancers

BACKGROUND

It was shown earlier that a number of CD207 positive Langerhans cells was lower in basal cell carcinomas than in the normal epidermis. Moreover, benign skin lesions presented a higher number of Langerhans cells when they were compared to malignant tumors.

AIM

To count Langerhans cells, assessing expression levels of CD1A and CD207 markers in actinic keratosis, basal and squamous cell carcinomas, compared with the normal skin. Comparison of Langerhans cells might give a valuable prognostic marker for skin cancer.

METHODS

Immunohistochemistry and methods of statistics were used.

RESULTS

Expression of CD1A and CD207 markers was assessed in tumor samples of actinic keratosis, cutaneous basal and squamous cell carcinomas, in comparison with the normal skin. In each cohort there were 40 patients (and 11 healthy individuals). We have shown that the number of Langerhans cells is considerably lower in cutaneous basal and squamous cell carcinomas, compared with their number in the normal skin (p < 0.0001).

CONCLUSIONS

CD1A expression correlated with CD207 expression only in the control group. There was no correlation in actinic keratosis, basal and squamous cell carcinoma. This may suggest an alteration of Langerhans cells phenotype in skin neoplastic diseases, making the number of Langerhans cells a valuable prognostic factor for skin tumors.

Clinical significance of mannose-binding lectin expression in thyroid carcinoma tissues

Mannose-binding lectin (MBL) plays an important role in the host defence against pathogens and carcinogenesis. This study aimed to analyze differential expression of MBL protein in thyroid cancer tissues and then to investigate the effects of rhMBL in thyroid cancer cells. Tissue specimens from 45 thyroid carcinoma patients and 45 adenoma patients were recruited for immunohistochemical analysis of MBL expression. Cell viability, apoptosis, RT-PCR and Western blot assays were used to detect changes in tumor cell viability, apoptosis, and gene expression, respectively, after treatment of thyroid cancer cells with rhMBL. MBL was differentially expressed in papillary thyroid carcinoma, adenoma, and the distant normal tissues (0.322 ± 0.008, 0.227 ± 0.003, and 0.113 ± 0.003, respectively, P < 0.05). MBL expression was associated with the advanced disease stage, histological grade, or lymph node metastasis in cancer patients (P < 0.05). Moreover, rhMBL treatment of thyroid cancer cells reduced tumor cell viability but induced apoptosis in a dose- and time-dependent manner. rhMBL treatment also downregulated Bcl2 protein expression in thyroid cancer cells (P < 0.05). In addition, expression p53 protein was increased in thyroid cancer cells after rhMBL treatment (P < 0.05). The data from the current study demonstrate that MBL overexpression is associated with advanced thyroid carcinomas, and rhMBL treatment significantly reduced viability but induced apoptosis of thyroid cancer cell lines. Further studies will clarify whether overexpressed MBL in thyroid cancer tissues is functional.

Classical and alternative activation of rat hepatic sinusoidal endothelial cells by inflammatory stimuli

The ability of rat hepatic sinusoidal endothelial cells (HSEC) to become activated in response to diverse inflammatory stimuli was analyzed. Whereas the classical macrophage activators, IFNγ and/or LPS upregulated expression of iNOS in HSEC, the alternative macrophage activators, IL-10 or IL-4+IL-13 upregulated arginase-1 and mannose receptor. Similar upregulation of iNOS and arginase-1 was observed in classically and alternatively activated Kupffer cells, respectively. Removal of inducing stimuli from the cells had no effect on expression of these markers, demonstrating that activation is persistent. Washing and incubation of IFNγ treated cells with IL-4+IL-13 resulted in decreased iNOS and increased arginase-1 expression, while washing and incubation of IL-4+IL-13 treated cells with IFNγ resulted in decreased arginase-1 and increased iNOS, indicating that classical and alternative activation of the cells is reversible. HSEC were more sensitive to phenotypic switching than Kupffer cells, suggesting greater functional plasticity. Hepatocyte viability and expression of PCNA, β-catenin and MMP-9 increased in the presence of alternatively activated HSEC. In contrast, the viability of hepatocytes pretreated for 2 h with 5 mM acetaminophen decreased in the presence of classically activated HSEC. These data demonstrate that activated HSEC can modulate hepatocyte responses following injury. The ability of hepatocytes to activate HSEC was also investigated. Co-culture of HSEC with acetaminophen-injured hepatocytes, but not control hepatocytes, increased the sensitivity of HSEC to classical and alternative activating stimuli. The capacity of HSEC to respond to phenotypic activators may represent an important mechanism by which they participate in inflammatory responses associated with hepatotoxicity.

Macrophage polarization induced by neuropeptide methionine enkephalin (MENK) promotes tumoricidal responses

The aim of this study is to investigate macrophages polarization induced by methionine enkephalin (MENK) that promotes tumoricidal responses in vivo and in vitro. Both phenotypic and functional activities of macrophages were assessed by the quantitative analysis of key surface molecules on macrophages with flow cytometry, immunofluorescent staining, and the production of cytokines with enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction. Our results showed that MENK could down-regulate the expression of CD206 and the production of arginase-1 (the markers of alternatively activated (M2) macrophage) in tumor-associated macrophages in vivo, meanwhile it could significantly up-regulate the expression of CD64, MHC-II, and the production of induced nitric oxide synthase (the markers of classically activated (M1) macrophages). Furthermore, the studies on bone marrow-derived macrophages treated with MENK (10(-12) M) in vitro had demonstrated that MENK could markedly increase tumoricidal activity. MENK could also enhance the release of reactive oxidant species and the production of interleukin-12p40, tumor necrosis factor-α, while decrease the production of interleukin-10. In conclusion, MENK could effectively induce M2 macrophages polarizing to M1 macrophages, sequentially to modulate the Th1 responses of the host immune system. Our results suggest that MENK might have great potential as a new therapeutic agent for cancer.

Macrophage sub-populations and the lipoxin A4 receptor implicate active inflammation during equine tendon repair

Macrophages (Mϕ) orchestrate inflammatory and reparatory processes in injured connective tissues but their role during different phases of tendon healing is not known. We investigated the contribution of different Mϕ subsets in an equine model of naturally occurring tendon injury. Post mortem tissues were harvested from normal (uninjured), sub-acute (3–6 weeks post injury) and chronically injured (>3 months post injury) superficial digital flexor tendons. To determine if inflammation was present in injured tendons, Mϕ sub-populations were quantified based on surface antigen expression of CD172a (pan Mϕ), CD14^highCD206^low (pro-inflammatory M1Mϕ), and CD206^high (anti-inflammatory M2Mϕ) to assess potential polarised phenotypes. In addition, the Lipoxin A₄ receptor (FPR2/ALX) was used as marker for resolving inflammation. Normal tendons were negative for both Mϕ and FPR2/ALX. In contrast, M1Mϕ predominated in sub-acute injury, whereas a potential phenotype-switch to M2Mϕ polarity was seen in chronic injury. Furthermore, FPR2/ALX expression by tenocytes was significantly upregulated in sub-acute but not chronic injury. Expression of the FPR2/ALX ligand Annexin A1 was also significantly increased in sub-acute and chronic injuries in contrast to low level expression in normal tendons. The combination of reduced FPR2/ALX expression and persistence of the M2Mϕ phenotype in chronic injury suggests a potential mechanism for incomplete resolution of inflammation after tendon injury. To investigate the effect of pro-inflammatory mediators on lipoxin A₄ (LXA₄) production and FPR2/ALX expression in vitro, normal tendon explants were stimulated with interleukin-1 beta and prostaglandin E₂. Stimulation with either mediator induced LXA₄ release and maximal upregulation of FPR2/ALX expression after 72 hours. Taken together, our data suggests that although tenocytes are capable of mounting a protective mechanism to counteract inflammatory stimuli, this appears to be of insufficient duration and magnitude in natural tendon injury, which may potentiate chronic inflammation and fibrotic repair, as indicated by the presence of M2Mϕ.

Skin-resident murine dendritic cell subsets promote distinct and opposing antigen-specific T helper cell responses

Skin-resident dendritic cells (DCs) are well positioned to encounter cutaneous pathogens and are required for the initiation of adaptive immune responses. There are at least three subsets of skin DC- Langerhans cells (LC), Langerin(+) dermal DCs (dDCs), and classic dDCs. Whether these subsets have distinct or redundant function in vivo is poorly understood. Using a Candida albicans skin infection model, we have shown that direct presentation of antigen by LC is necessary and sufficient for the generation of antigen-specific T helper-17 (Th17) cells but not for the generation of cytotoxic lymphocytes (CTLs). In contrast, Langerin(+) dDCs are required for the generation of antigen specific CTL and Th1 cells. Langerin(+) dDCs also inhibited the ability of LCs and classic DCs to promote Th17 cell responses. This work demonstrates that skin-resident DC subsets promote distinct and opposing antigen-specific responses.

IL-4Ralpha-independent expression of mannose receptor and Ym1 by macrophages depends on their IL-10 responsiveness

IL-4Ralpha-dependent responses are essential for granuloma formation and host survival during acute schistosomiasis. Previously, we demonstrated that mice deficient for macrophage-specific IL-4Ralpha (LysM(cre)Il4ra(-/lox)) developed increased hepatotoxicity and gut inflammation; whereas inflammation was restricted to the liver of mice lacking T cell-specific IL-4Ralpha expression (iLck(cre)Il4ra(-/lox)). In the study presented here we further investigated their role in liver granulomatous inflammation. Frequencies and numbers of macrophage, lymphocyte or granulocyte populations, as well as Th1/Th2 cytokine responses were similar in Schistosoma mansoni-infected LysM(cre)Il4ra(-/lox) liver granulomas, when compared to Il4ra(-/lox) control mice. In contrast, a shift to Th1 responses with high IFN-gamma and low IL-4, IL-10 and IL-13 was observed in the severely disrupted granulomas of iLck(cre)Il4ra(-/lox) and Il4ra(-/-) mice. As expected, alternative macrophage activation was reduced in both LysM(cre)Il4ra(-/lox) and iLck(cre)Il4ra(-/lox) granulomas with low arginase 1 and heightened nitric oxide synthase RNA expression in granuloma macrophages of both mouse strains. Interestingly, a discrete subpopulation of SSC(high)CD11b+I-A/I-E(high)CD204+ macrophages retained expression of mannose receptor (MMR) and Ym1 in LysM(cre)Il4ra(-/lox) but not in iLck(cre)Il4ra(-/lox) granulomas. While aaMphi were in close proximity to the parasite eggs in Il4ra(-/lox) control mice, MMR+Ym1+ macrophages in LysM(cre)Il4ra(-/lox) mice were restricted to the periphery of the granuloma, indicating that they might have different functions. In vivo IL-10 neutralisation resulted in the disappearance of MMR+Ym1+ macrophages in LysM(cre)Il4ra(-/lox) mice. Together, these results show that IL-4Ralpha-responsive T cells are essential to drive alternative macrophage activation and to control granulomatous inflammation in the liver. The data further suggest that in the absence of macrophage-specific IL-4Ralpha signalling, IL-10 is able to drive mannose receptor- and Ym1-positive macrophages, associated with control of hepatic granulomatous inflammation.

Construction of flocculent industrial yeast by the yeast flocculation gene FLO1

The structure gene FLO1 from Saccharomyces cerevisiae W303-1A encoding a flocculation protein and the G418 resistance gene kanMX from plasmid pUG6 were amplified by PCR method. The expression vector pYX212 harboring FLO1 gene and kanMX gene was transformed into Angel yeast. The transformant Angel yeast F6 was obtained and showed strong and stable flocculation ability during 20 batches inoculation. And the flocculation ability of the transformant Angel yeast F6 showed no difference in the medium with the initial pH ranging from 3.5 to 6.0. Noteworthily, the flocculation onset of the transformant strain was in the early stationary growth phase, not coincident with the glucose depletion in the cultural medium. And in the experiment the ethanol yield and other properties of the transformant Angel yeast F6 were similar to those of the wild-type strain, although its fermentation time was a little slower comparing with the wild-type strain. Those would be potential application for yeast cells to separate and recycle in the fuel ethanol industry.

Activin A induces Langerhans cell differentiation in vitro and in human skin explants

Langerhans cells (LC) represent a well characterized subset of dendritic cells located in the epidermis of skin and mucosae. In vivo, they originate from resident and blood-borne precursors in the presence of keratinocyte-derived TGFbeta. In vitro, LC can be generated from monocytes in the presence of GM-CSF, IL-4 and TGFbeta. However, the signals that induce LC during an inflammatory reaction are not fully investigated. Here we report that Activin A, a TGFbeta family member induced by pro-inflammatory cytokines and involved in skin morphogenesis and wound healing, induces the differentiation of human monocytes into LC in the absence of TGFbeta. Activin A-induced LC are Langerin+, Birbeck granules+, E-cadherin+, CLA+ and CCR6+ and possess typical APC functions. In human skin explants, intradermal injection of Activin A increased the number of CD1a+ and Langerin+ cells in both the epidermis and dermis by promoting the differentiation of resident precursor cells. High levels of Activin A were present in the upper epidermal layers and in the dermis of Lichen Planus biopsies in association with a marked infiltration of CD1a+ and Langerin+ cells. This study reports that Activin A induces the differentiation of circulating CD14+ cells into LC. Since Activin A is abundantly produced during inflammatory conditions which are also characterized by increased numbers of LC, we propose that this cytokine represents a new pathway, alternative to TGFbeta, responsible for LC differentiation during inflammatory/autoimmune conditions.

Human CD34+ CD11b- cord blood stem cells generate in vitro a CD34- CD11b+ subset that is enriched in langerin+ Langerhans dendritic cell precursors

OBJECTIVE

We investigated whether the expression of CD11b on precursors derived in vitro from CD34+ hematopoietic stem cells was related to their ability to generate CD11b- and CD11b+ Langerhans dendritic cells (LC).

METHODS

Human CD34+ cells purified from cord blood were cultured with FLT3 ligand, thrombopoietin, and stem cell factor (FTS) for 2 weeks, analyzed, and sorted by FACS. Sorted fractions were cultured as above, or differentiated into LC with GM-CSF, IL-4, and TGF-beta1 (G4-TGF) for 6 days. The capacity of LC to internalize langerin and dextran was assessed.

RESULTS

Ex vivo, human CD34+ cells were CD11b- and mostly CLA+. After 2 weeks of culture with FTS, CD34- CLA- CD11b- and CD34- CLA- CD11b+ cells emerged. CD11b- cells were the most ancestral because they were the only ones to proliferate with FTS, and constantly generated CD11b+ cells. Both CD11b- and CD11b+ sorted cells generated E-cadherin+ langerin+ LC after incubation with G4-TGF. The former fraction contained 46% +/- 15% of E-cadherin+ and 10% +/- 5% of langerin+ cells, whereas in the latter fraction these values reached respectively 66% +/- 23% and 30% +/- 16% (mean +/- SD, n = 7, p < 0.056). Looking at functional properties, CD11b- and CD11b+ LC were similar in terms of langerin and dextran endocytosis. By contrast, only CD11b+ LC internalized fluorescent LPS.

CONCLUSION

Human CD34+ CD11b- cells differentiate in FTS culture into a CD34- CD11b- precursor that in turn generates CD34- CD11b+ cells. These cells are enriched in LC precursors compared to CD34- CD11b- cells. Both CD11b- and CD11b+ LC are generated in vitro, and each fraction may assume different functions in inflammatory situations.

Antigenic targeting of the human mannose receptor induces tumor immunity

Pattern recognition receptors are preferentially expressed on APCs allowing selective uptake of pathogens for the initiation of antimicrobial immunity. In particular, C-type lectin receptors, including the mannose receptor (MR), facilitate APC-mediated adsorptive endocytosis of microbial glyconjugates. We have investigated the potential of antigenic targeting to the MR as a means to induce Ag-specific humoral and cellular immunity. hMR transgenic (hMR Tg) mice were generated to allow specific targeting with the anti-hMR Ab, B11. We show that hMR targeting induced both humoral and cellular antigenic specific immunity. Immunization of hMR Tg mice with B11 mAbs induced potent humoral responses independent of adjuvant. Injection of hMR Tg mice with mouse anti-hMR Ab clone 19.2 elicited anti-Id-specific humoral immunity while non-Tg mice were unresponsive. B11-OVA fusion proteins (B11-OVA) were efficiently presented to OVA-specific CD4 and CD8 T cells in MR Tg, but not in non-Tg, mice. Effector differentiation of responding T cells in MR Tg mice was significantly enhanced with concomitant immunization with the TLR agonist, CpG. Administration of both CpG and B11-OVA to hMR Tg mice induced OVA-specific tumor immunity while WT mice remained unprotected. These studies support the clinical development of immunotherapeutic approaches in cancer using pattern recognition receptor targeting systems for the selective delivery of tumor Ags to APCs.

Langerin-expressing and CD83-expressing cells in oral lichen planus lesions

OBJECTIVE

Dendritic Langerhans cells (LCs) have been attributed a role in the pathogenesis of lichen planus as autoantigen-presenting cells initiating expansion of autoreactive T cells. Langerin and CD83, which are cell molecules expressed on LCs, are associated with antigen presentation. The present study examined expression of Langerin and CD83 molecules on LCs in patients with oral lichen planus (OLP).

MATERIAL AND METHODS

Biopsies were obtained from seven patients with OLP. Oral mucosa from seven healthy subjects served as controls. Monoclonal antibodies (mAbs) were used in standard immunohistochemical procedures to visualize CD1a-, Langerin-, and CD83-molecule-expressing cells.

RESULTS

CD1a+ and Langerin+ cells were found in significantly higher frequencies in OLP epithelium compared with healthy oral epithelium (p<0.01 and p<0.05, respectively); however, the frequency of CD83+ cells did not differ (p>0.05). The connective tissue in OLP lesions showed significantly higher frequencies of CD1a+, Langerin+, and CD83+ cells compared with healthy connective tissue (p<0.01, p<0.01, and p<0.05). CD1a+ and Langerin+ cells in OLP and healthy epithelium had a dendritic morphology.

CONCLUSIONS

The study shows increased numbers of CD1a- and Langerin-expressing LCs in OLP compared with healthy controls. In the connective tissue, CD83+ cells with dendritic morphology were localized to regions of lymphocyte clusters. The presence of CD83+ dendritic cells in areas of lymphocyte clusters in the connective tissue of OLP lesions indicates the possibility of ongoing autoantigen presentation.

In melanoma changes of immature and mature dendritic cell expression correlate with tumor thickness:an immunohistochemical study

Cells with a dendritic morphology and/or expression of dendritic cell (DC) markers have been repeatedly described in several human tumors, but the distribution and density of melanoma-associated DCs have not yet been reported. The aim of the present study is to analyze the density and topographical distribution of melanoma-associated DCs and their relation with CD3(+), CD4(+) and CD8(+) T lymphocytes in forty cases of cutaneous human melanoma. In melanocytic tumours different pools of DCs were recognised in the epidermis and in the dermis, particularly in intimate relation with lymphocyte clusters inside the melanocytic proliferation, and more often at the edges of tumours. The number of Langerin-positive DCs showed an inverse correlation with tumour depth (correlation coefficient r= -0.59, P=0.0001) and was significantly lower in thick melanomas compared to thin and intermediate ones (P<0.0005). The density of CD83(+) DCs was significantly lower in thick melanomas compared to thin and intermediate ones (P<0.009). A significant correlation was found between the density of the two DCs subsets (r=0.57, p<0.0001). The number of CD3(+) lymphocytes was inversely correlated to the depth of infiltration (r=-0.596, P<0.0001): melanoma cases with II-III Clark level showed a higher T lymphocyte mean density compared to cases with IV-V Clark level (P<0.0001). T lymphocyte density was significantly lower in thick melanomas compared to thin and intermediate melanomas (P<0.0005). In conclusion, our study indicates a progressive loss of DCs and T lymphocytes in the neoplastic progression of melanomas; further identification of the molecular pathways involved in the functional impairment of these immunitary cells may lead to new immunotherapeutic approaches for melanoma patients that would improve the clinical outcome of the patients.

Cloning and expression of a mannose-binding jacalin-related lectin from leaves of Japanese cycad (Cycas revoluta Thunb.)

Cycad leaf lectin (CRLL), a mannose-recognizing jacalin-related lectin (mJRL), was first cloned as a gymnosperm lectin and expressed. The cDNA sequence of CRLL (DDBJ, accession no. AB198328), coding 291 amino acid residues, has a tandem repeat of about 150 amino acids divided into N- and C-terminal domains as Japanese chestnut mJRL. Sequence alignment showed deletion and insertion of the sequence, and its putative carbohydrate-binding sites showed some differences from other JRLs. PCR analysis showed that this lectin was expressed in the cycad leaf but not in the root or seed. Recombinant CRLL (rCRLL) was expressed in Escherichia coli and purified by affinity chromatography after refolding procedures. Properties of active rCRLL appeared to be almost the same as those of native CRLL.

A CD34(+) human cell line model of myeloid dendritic cell differentiation: evidence for a CD14(+)CD11b(+) Langerhans cell precursor

The study of early events in dendritic cell (DC) differentiation is hampered by the lack of homogeneous primary cell systems that allow the study of cytokine-driven, transitional DC differentiation steps. The CD34(+) acute myeloid leukemia cell line MUTZ-3 displays a unique ability to differentiate into interstitial DC (IDC) and Langerhans cells (LC) in a cytokine-dependent manner. Phenotypic characterization revealed MUTZ-3 to consist of three distinct subpopulations. Small CD34(+)CD14(-)CD11b(-) progenitors constitute the proliferative compartment of the cell line with the ability to differentiate through a CD34(-)CD14(-)CD11b(+) stage to ultimately give rise to a morphologically large, nonproliferating CD14(+)CD11b(hi) progeny. These CD14(+)CD11b(hi) cells were identified as common, immediate myeloid DC precursors with the ability to differentiate into LC and IDC, exhibiting characteristic and mutually exclusive expression of Langerin and DC-specific ICAM-grabbing nonintegrin, respectively. The identity of the MUTZ-3-derived LC subset was confirmed further by the presence of Birbeck granules. We conclude that the MUTZ-3 cell line provides a ready and continuous supply of common myeloid precursors, which should facilitate further study of the ontogeny of myeloid DC lineages.

Molecular cloning and characterisation of two homologues of Mannose-Binding Lectin in rainbow trout

Mannose-binding lectin (MBL) is a C-type lectin which participates in the innate immune system as an activator of the complement system and as opsonin after binding to certain carbohydrate structures on microorganisms and pathogens. C-type lectins are all Ca(2+)-dependent molecules and they share a tightly folded carbohydrate recognition domain (CRD). In this report the isolation and characterisation of cDNA transcripts encoding two mannose-binding lectin isoforms MBL-1 and MBL-2 from rainbow trout (Oncorhynchus mykiss) is presented. The deduced amino acid sequences of trout MBL-1 and MBL-2 (185 and 186 aa, respectively) present 83% identity to each other, exhibiting the highest identity score 46, 46 and 42% with the Atlantic salmon, shishamo smelt and zebrafish counterparts, respectively. The identity to birds and mammalian MBLs ranges from 25 to 33%. The trout MBL-1 and MBL-2 contain the EPN motif of mannose-binding C-type lectins, important for mannose specificity and they are expressed exclusively in liver and spleen, respectively.

Mast Cells Have a Pivotal Role in TNF-Independent Lymph Node Hypertrophy and the Mobilization of Langerhans Cells in Response to Bacterial Peptidoglycan

Peptidoglycan (PGN) from Gram-positive bacteria, activates multiple immune effector cells. PGN-induced lymph node (LN) hypertrophy and dendritic cell mobilization in vivo were investigated following PGN injection into the skin. Both LN activation and the migration of Langerhans cells (LCs) to draining LNs were dependent on the presence of mast cells as demonstrated using mast cell deficient W/W(v) mice. However, these responses did not require TLR2, TLR4, or MYD88. TNF-deficient mice exhibited normal increases in LN cellularity but significantly reduced LC migration. In contrast, responses to IgE-mediated mast cell activation were highly TNF dependent. Complement component C3-deficient mice showed decreased LN hypertrophy and abrogated LC migration in response to PGN. These data demonstrate a critical role for mast cells and complement in LN responses to PGN and illustrate a novel TNF-independent mechanism whereby mast cells participate in the initiation of immunity.

Expression of human DEC-205 (CD205) multilectin receptor on leukocytes

DEC-205 (CD205) belongs to the macrophage mannose receptor family of C-type lectin endocytic receptors and behaves as an antigen uptake/processing receptor for dendritic cells (DC). To investigate DEC-205 tissue distribution in human leukocytes, we generated a series of anti-human DEC-205 monoclonal antibodies (MMRI-5, 6 and 7), which recognized epitopes within the C-type lectin-like domains 1 and 2, and the MMRI-7 immunoprecipitated a single approximately 200 kDa band, identified as DEC-205 by mass spectrometry. MMRI-7 and another DEC-205 mAb (MG38), which recognized the epitope within the DEC-205 cysteine-rich and fibronectin type II domain, were used to examine DEC-205 expression by human leukocytes. Unlike mouse DEC-205, which is reported to have predominant expression on DC, human DEC-205 was detected by flow cytometry at relatively high levels on myeloid blood DC and monocytes, at moderate levels on B lymphocytes and at low levels on NK cells, plasmacytoid blood DC and T lymphocytes. MMRI-7 F(ab')2 also labeled monocytes, B lymphocytes and NK cells similarly excluding reactivity due to non-specific binding of the mAb to FcgammaR. Tonsil mononuclear cells showed a similar distribution of DEC-205 staining on the leukocytes. DEC-205-specific semiquantitative immunoprecipitation/western blot and quantitative reverse transcriptase-PCR analysis established that these leukocyte populations expressed DEC-205 protein and the cognate mRNA. Thus, human DEC-205 is expressed on more leukocyte populations than that were previously assumed based on mouse DEC-205 tissue localization studies. The broader DEC-205 tissue expression in man is relevant to clinical DC targeting strategies and DEC-205 functional studies.

Macrophage activation and human immunodeficiency virus infection: HIV replication directs macrophages towards a pro-inflammatory phenotype while previous activation modulates macrophage susceptibility to infection and viral production

Macrophages are pivotal for the regulation of immune and inflammatory responses, but whether their role in HIV infection is protective or deleterious remains unclear. In this study, we investigated the effect of pro- and anti-inflammatory stimuli on macrophage sensitivity to two different aspects of HIV infection: their susceptibility to infection stricto sensu, which we measured by endpoint titration method, and their ability to support virus spread, which we measured by using an RT activity assay in infection kinetics. We show a partially protective role for pro-inflammatory agents as well as for IL-4. We also illustrate that various different stimuli display differential effects on macrophage susceptibility to HIV and on virus replication that occurs thereafter. On the other hand, HIV replication strongly repressed CD206 and CD163 expression, thus clearly orientating macrophages towards a pro-inflammatory phenotype, but independently of TNF. Taken together, our results emphasize that HIV infection of macrophages sets up inflammation at the cell level but through unexpected mechanisms. This may limit target susceptibility and participate in virus clearance but may also result in tissue damage.

Decoy molecules based on PNA-DNA chimeras and targeting Sp1 transcription factors inhibit the activity of urokinase-type plasminogen activator receptor (uPAR) promoter

The expression levels of urokinase-type plasminogen activator receptor (uPAR) are strongly correlated with metastatic potential in human cancer cell lines of melanoma, breast, lung, and colon. Therefore, targeting of uPAR could have practical implications in the treatment of neoplastic diseases. Because the expression of uPAR is regulated at the level of transcription in part by Sp1, we designed and tested transcription factors decoy molecules targeting Sp1 with the aim of inhibiting uPAR gene expression. The main objective of the present study was to determine whether decoy molecules based on peptide nucleic acids (PNA)-DNA chimeras mimicking Sp1 binding sites might be proposed as useful reagents to alter expression of Sp1-regulated genes involved in tumor invasion and metastasis. The results obtained firmly indicate that Sp1 binding molecules based on PNA-DNA-PNA chimeras are powerful decoys, as they efficiently inhibit the interactions between Sp1 and the uPAR promoter elements. Experiments performed on hepatoma HepG2 cells transfected with a plasmid containing the firefly luciferase gene reporter under the control of the human uPAR promoter demonstrate that PNA-DNA-PNA-based decoy molecules are potent inhibitors of the transcriptional activity of the uPAR promoter. Our results suggest that these molecules warrant attention for the design of novel antimetastatic drugs.

Effects of Galanthus nivalis agglutinin (GNA) expressed in tomato leaves on larvae of the tomato moth Lacanobia oleracea (Lepidoptera: Noctuidae) and the effect of GNA on the development of the endoparasitoid Meteorus gyrator (Hymenoptera: Braconidae)

The effect of ingestion of transgenic tomato leaves expressing the plant lectin Galanthus nivalis agglutinin (GNA) on development of larvae of Lacanobia oleracea (Linnaeus) was studied under laboratory conditions. When L. oleracea larvae were fed on tomato line 14.1H, expressing approximately 2.0% GNA, significant increases in the mean larval weight and in the amount of food consumed were found. This resulted in an overall reduction in the mean development time to the pupal stage of approximately 7 days. A significant increase in the percentage survival to the adult moth was also recorded when newly hatched larvae were reared on transgenic tomato leaves (72%) compared to larvae reared on untransformed leaves (40%). The effects of ingestion of GNA by L. oleracea larvae, via artificial diet or the leaves of transgenic tomato or potato plants, on the subsequent development of its solitary endoparasitoid Meteorus gyrator (Thunberg) was also studied. No significant effects on the life cycle parameters of M. gyrator developing in L. oleracea fed on GNA-containing diets were observed. Experiments with transgenic potato plants indicated that the stadium of the host larvae at parasitism had a greater influence on M. gyrator development than the presence of GNA. Potential GNA-binding glycoproteins were detected in the gut and body tissues of larval M. gyrator. Despite detection in host tissues, GNA could not be detected in adult M. gyrator and therefore it is likely that at the time of pupation M. gyrator are able to void the GNA in the meconial pellet.

Estrogen selectively promotes the differentiation of dendritic cells with characteristics of Langerhans cells

The steroid hormone estrogen regulates the differentiation, survival, or function of diverse immune cells. Previously, we found that physiological amounts of 17beta-estradiol act via estrogen receptors (ER) to promote the GM-CSF-mediated differentiation of dendritic cells (DC) from murine bone marrow progenitors in ex vivo cultures. Of the two major subsets of CD11c(+) DC that develop in these cultures, estrogen is preferentially required for the differentiation of a CD11b(int)Ly6C(-) population, although it also promotes increased numbers of a CD11b(high)Ly6C(+) population. Although both DC subsets express ERalpha, only the CD11b(high)Ly6C(+) DC express ERbeta, perhaps providing a foundation for the differential regulation of these two DC types by estrogen. The two DC populations exhibit distinct phenotypes in terms of capacity for costimulatory molecule and MHC expression, and Ag internalization, which predict functional differences. The CD11b(int)Ly6C(-) population shows the greatest increase in MHC and CD86 expression after LPS activation. Most notably, the estrogen-dependent CD11b(int)Ly6C(-) DC express langerin (CD207) and contain Birbeck granules characteristic of Langerhans cells. These data show that estrogen promotes a DC population with the unique features of epidermal Langerhans cells and suggest that differentiation of Langerhans cells in vivo will be dependent upon local estrogen levels and ER-mediated signaling events in skin.

Functional GNA expressed in Escherichia coli with high efficiency and its effect on Ceratovacuna lanigera Zehntner

The mannose-specific GNA (Galanthus nivalis agglutinin, snowdrop lectin) are the resistant proteins with many bioactivities. Snowdrop lectin is different with plant organs and development periods in lectin species, content, and bioactivities. It is an effective and cheap way to obtain much active GNA through overexpression of GNA gene in Escherichia coli. Constructs encoding mature GNA fused with an N-terminal pelB signal sequence protein (PelB) were expressed in E. coli with high efficiency. Recombinant protein productivity was higher than values published before. The insecticidal activity of purified recombinant proteins was assayed on feeding sugarcane wooly aphid (Ceratovacuna lanigera Zehntner), as well as spraying on sugarcane plants infected by aphids. The insecticidal activity was found to be comparable to native GNA. Oral delivery has obvious positive implications for crop protection against insect pests since peptides can be present in, or sprayed on, plant tissues susceptible to damage. A highly efficient expression of functional recombinant GNA would decrease the cost of GNA and promote its wide use, especially to give crop protection in the field.

HIV-1 TAT represses transcription of the bone morphogenic protein receptor-2 in U937 monocytic cells

The bone morphogenetic protein receptor-2 (BMPR2) is a member of the transforming growth factor-beta receptor family and is expressed on the surface of several cell types including endothelial cells and macrophages. Recently, a cause for familial primary pulmonary hypertension (FPPH) has been identified as mutations in the gene encoding BMPR2. Three forms of pulmonary hypertension (PH) exist, including PPH, FPPH, and PH secondary to other etiologies (sporadic PH) such as drug abuse and human immunodeficiency virus (HIV) infection. It is interesting that these subtypes are histologically indistinguishable. The macrophage is a key target cell for HIV-1, significantly altering macrophage cell function upon infection. HIV-1 trans-activator of transcription (Tat), an immediate-early product of the HIV-1 lifecycle, plays an important role in mediating HIV-induced modulation of host cell function. Our laboratory has previously shown that Tat represses mannose receptor transcription in macrophages. In the current study, we examined activity from the BMPR2 promoter in the macrophage cell line U937 and potential regulation by Tat. Transfection of U937 cells with BMPR2 promoter-reporter constructs revealed dose-dependent repression of BMPR2 promoter activity in the presence of Tat. Experiments using truncations of the BMPR2 promoter localized Tat-mediated repression to the first 208 bases of the promoter. Decreased BMPR2 transcription resulted in altered downstream signaling. Similar to mothers against decapentaplegics (SMAD) phosphorylation and SMAD6 expression, in response to BMP2 treatment, were down-regulated after Tat treatment. Finally, HIV-1 infection and treatment with Tat protein of the U937 human monocytic cell line resulted in a decreased, endogenous BMPR2 transcript copy number.

Pulmonary Surfactant Protein A Activates a Phosphatidylinositol 3-Kinase/Calcium Signal Transduction Pathway in Human Macrophages: Participation in the Up-Regulation of Mannose Receptor Activity

Surfactant protein A (SP-A), a major component of lung surfactant, binds to macrophages and has been shown to alter several macrophage biological functions, including up-regulation of macrophage mannose receptor (MR) activity. In the present study, we show that SP-A induces signal transduction pathway(s) that impact on MR expression. The addition of human, rat, or recombinant rat SP-A to human monocyte-derived macrophages significantly raised the level of cytosolic Ca2+ above baseline within 10 s of SP-A addition, as measured by spectrofluorometric analysis. SP-A induced a refractory state specific for SP-A consistent with homologous desensitization of a receptor(s) linked to calcium mobilization because a second application of SP-A did not induce a rise in cytosolic Ca2+ whereas the addition of platelet-activating factor did. Using site-directed mutations in SP-A, we determined that both the attached sugars and the collagen-like domain of SP-A are necessary to optimize Ca2+ mobilization. SP-A triggered the increase in cytosolic Ca2+ by inducing activation of phospholipase C, which leads to the hydrolysis of membrane phospholipids, yielding inositol 1,4,5-trisphosphate and mobilizing intracellularly stored Ca2+ by inositol triphosphate-sensitive channels. Finally, inhibition of PI3Ks, which appear to act upstream of phospholipase C in Ca2+ mobilization, decreased the SP-A-induced rise in MR expression, providing evidence that SP-A induction of MR activity involves the activation of a pathway in which PI3K is a component. These studies provide further evidence that SP-A produced in the lung plays a role in modulating macrophage biology, thereby contributing to the alternative activation state of the alveolar macrophage.

Production of large numbers of Langerhans' cells with intraepithelial migration ability in vitro

Langerhans' cells (LCs) are a subset of immature dendritic cells (DCs) and play a key role in the initiation and regulation of immune responses. Functional studies of these cells have been hampered by difficulties in generating a large number of LCs in vitro. We describe a new method to efficiently generate immature DCs exhibiting morphological, immunohistochemical, and ultrastructural features of LCs (CD1a+, Birbeck Granules+, CD207+, E-cadherin+, cutaneous lymphocyte-associated antigen+, and CCR6+) from a limited number of CD34+ cord blood progenitors. This method is based on a two-step procedure consisting of an amplification phase followed by a terminal differentiation induction. The amplification step is initiated with a combination of hematopoietic growth factors (thrombopoietin/stem cell factor/fetal liver tyrosine kinase-3 ligand), cytokines (granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and interleukin-4), and 5 ng/ml of transforming growth factor (TGF)-beta1. The differentiation is induced by increasing the concentration of TGF-beta1 to 12.5 ng/ml. These culture conditions were efficient for generating a large number of immature LCs (8.74 x 10(6) +/- 3.2) from 15 x 10(4) CD34+ progenitor cells. In addition, these LCs were shown to be able to infiltrate an in vitro reconstructed epithelium. Because LCs play an important role in the mucosal immunity, this technique could be useful to study their interactions with epithelial pathogenic agents and to perform pharmacological, toxicological, and clinical research.

Enhanced expression of the mannose receptor by endothelial cells of the liver and spleen microvascular beds in the macrophage-deficient PU.1 null mouse

Mice null for the haematopoietic lineage-specific transcription factor PU.1 lack mature Mphi and are compromised in their ability to clear cellular debris from the blood circulation. We investigated the possibility that non-professional phagocytes may partially compensate for the lack of Mphi in clearance functions. In the absence of Kupffer cells (resident liver Mphi) in the PU.1 null mice, electron microscopy revealed ingested debris in sinusoidal endothelial cells and hepatocytes although debris was also seen free in blood vessels. To investigate whether an increased clearance function of non-professional phagocytes might be linked to expression of Mphi-associated phagocytic and pinocytic receptors by other cells in PU.1 null mouse, we examined expression of several candidate proteins by immunocytochemistry and Western blotting. We found mannose receptor (MR) comparably expressed in PU.1 null and PU.1+ mice liver and spleen whereas class A scavenger receptor was substantially reduced and complement receptor 3 was absent in PU.1 null animals. By morphometric analysis, liver and spleen sinusoidal endothelial cells were seen to express significantly more MR in the PU.1 null mouse. This study provides the first evidence of apparently compensatory alterations in the microvasculature of the Mphi-deficient PU.1 null mouse.

Mannose receptor expression specifically reveals perivascular macrophages in normal, injured, and diseased mouse brain

Perivascular macrophages are believed to have a significant role in inflammation in the central nervous system (CNS). They express a number of different receptors that point toward functions in both innate immunity, through pathogen-associated molecular pattern recognition, phagocytosis, and cytokine responsiveness, and acquired immunity, through antigen presentation and co-stimulation. We are interested in the receptors that are differentially expressed by perivascular macrophages and microglia in both the normal CNS as well as in neuroinflammation and neurodegeneration. In this article we report the use of a well-characterized monoclonal antibody, 5D3, to localize the expression of the mannose receptor to perivascular macrophages in the normal CNS and in various models of brain pathology. Mannose receptor expression was limited to perivascular, meningeal, and choroid plexus macrophages in normal, inflamed, injured, and diseased CNS. In particular, activated microglia and invading hematogenous leukocytes were mannose receptor negative while expressing the F4/80 antigen, macrosialin (CD68), FcRII (CD32), scavenger receptor (CD204), and CR3 (CD11b/CD18). Since the perivascular macrophages expressing the mannose receptor are known to be the only constitutively phagocytic cells in the normal CNS, we injected clodronate-loaded liposomes intracerebroventricularly in control mice to deplete these cells. In these mice, there was no detectable mannose receptor expression in perivascular spaces after immunocytochemistry with the 5D3 monoclonal antibody. This finding underlines the value of the monoclonal antibody 5D3 as a tool to study murine perivascular macrophages selectively. Mannose receptor expression by macrophages located at blood-brain (perivascular), brain-cerebrospinal fluid (CSF) (meningeal), and CSF-blood (choroid plexus) interfaces supports a functional role of these cells in responding to external stimuli such as infection.

The expression of mannose receptors in skin fibroblast and their involvement in Leishmania (L.) amazonensis invasion

Leishmania are protozoa that invade mononuclear phagocytes with the involvement of different ligand-receptor systems, including mannose receptors. Until now, scant data are available concerning the mechanisms that govern the infection of Leishmania in other host cell types such as fibroblasts. Our aim was to analyze the expression of mannose receptors in primary cultures of skin fibroblasts (SF) further characterizing their role during the invasion of promastigotes of Leishmania (L.) amazonensis. Both fluorescent, light, and electron microscopy assays revealed that SF have mannose receptors since they bound and internalized mannosylated ligands in addition to being positively labeled by fuc-BSA-FITC probes. d-mannose competition assays revealed the participation of mannose receptors during the parasite association with SF presenting upregulated receptor expression during the initial steps of the infection. After longer periods of Leishmania:fibroblasts contact, the modulation noted in the host mannose receptors was reverted concomitantly to the infection control, suggesting that the parasites were required for the alteration maintenance and providing evidences that the SF may display microbicidal mechanisms to control the Leishmania infection.

Dendritic cell infiltration and prognosis of early stage breast cancer

PURPOSE

Although dendritic cells (DC) and T cells can infiltrate primary breast carcinoma, it remains unclear whether the immune response influences the clinical outcome.

EXPERIMENTAL DESIGN

T lymphocytes and DC infiltration within primary tumors was investigated in 152 patients with invasive nonmetastatic breast cancer. CD1a, CD3, CD68, CD123, CD207/Langerin, and CD208/DC-LAMP expression was assessed with semiquantitative immunohistochemical analysis. Expression of chemokines involved in DC migration (MIP-3a/CCL20, MIP-3b/CCL19, and 6Ckine/CCL21) was also examined. The correlation between these markers and the characteristics of the tumors, as well as relapse-free and overall survival was analyzed. Significant prognostic parameters were then tested in a validation series.

RESULTS

Infiltration by immature CD207/Langerin+ DC was found in a third of the cancers and did not correlate with clinicopathological data. Presence of mature CD208/DC-LAMP+ DC (56%) and CD3+ T cells (82%) strongly correlated with lymph node involvement and tumor grade. Among the chemokines analyzed, only the presence of MIP-3b/CCL19 in 57% of the tumors correlated with prolonged overall survival. CD123+ plasmacytoid DC (pDC) infiltrated 13% of the primary tumors. Their presence was strongly associated with shorter overall survival (93% versus 58% at 60 months) and relapse-free survival (90% versus 37% at 60 months) and was found to be an independent prognostic factor for overall survival and relapse-free survival and confirmed in an independent validation series of 103 patients.

CONCLUSIONS

Infiltration by pDC of primary localized breast tumor correlates with an adverse outcome, suggesting their contribution in the progression of breast cancer.

Large-scale production and purification of recombinant Galanthus nivalis agglutinin (GNA) expressed in the methylotrophic yeast Pichia pastoris

The gene coding for agglutinin from Galanthus nivalis (GNA) was expressed in, and secreted by, the methylotrophic yeast, Pichia pastoris. Transformants of P. pastoris were selected and a process to produce and purify gram quantities of recombinant GNA was developed. GNA was secreted at approximately 80 mg l(-1) at the 200 1 scale and was purified to 95% homogeneity using hydrophobic interaction chromatography. The recombinant protein was similar to the protein synthesised in plant with respect to structure and biological activity.

CD8 alpha- and Langerin-negative dendritic cells, but not Langerhans cells, act as principal antigen-presenting cells in leishmaniasis

In the early phase of leishmaniasis three types of potential antigen-presenting cells, including epidermal Langerhans cells (LC), dermal dendritic cells (DC) and inflammatory DC, are localized at the site of infection. Therefore, it has been a central question which cell type is responsible for the initiation of a protective immune response. In the early stage of an anti-Leishmania immune response, detectable Leishmania major antigen was localized in the paracortex of the draining lymph nodes (LN). Characterization of antigen-positive cells showed that L. major co-localized with DC of a CD11c(+) CD8 alpha(-) Langerin(-) phenotype. To determine the area of antigen uptake, dermis or epidermis, and to further define the type of antigen-transporting cells, L. major was inoculated subcutaneously and concurrently LC were mobilized with fluorescein isothiocyanate (FITC). After 3 days, DC carrying L. major antigen were always FITC(-), indicating a dermal and not an epidermal origin. Moreover, addition of L. major antigen to ex vivo isolated CD8 alpha(-) and CD8 alpha(+) DC from the draining LN of L. major-infected C57BL/6 mice demonstrated that both DC subpopulations were able to stimulate antigen-specific T cell proliferation in vitro. Without addition of exogenous antigen only the CD8 alpha(-) Langerin(-) DC were capable of stimulating antigen-specific T cell proliferation. Thus, we demonstrate that CD8 alpha(-) Langerin(-) DC and not LC are the basis of the protective immune response to intracellular L. major parasites in vivo.

Macrophage mannose receptor in chronic sinus disease

BACKGROUND

The role of infectious agents in the onset and maintenance of chronic sinus disease is still not fully understood. Macrophage mannose receptor (MMR), an innate pattern recognizing receptor, capable of phagocytosis of invaders and signal transduction for proinflammatory mechanisms, might be of importance in immune interactions in chronic sinus disease.

OBJECTIVE

We examined the MMR in sinonasal airway mucosa to evaluate its possible role in chronic rhinosinusitis (CS) and nasal polyposis (NPs).

METHODS

Surgical samples from patients with sinonasal disease were investigated with real-time RT-PCR for quantification of MMR mRNA expression, and the presence and location of MMR-positive cells was analysed by immunohistochemistry.

RESULTS

Quantification of MMR mRNA showed a statistically significant higher expression in NPs compared to CS without NP and controls. Immunohistochemistry revealed expression of MMR in all tissue samples; however, in NP we found an enhanced positive cellular staining including cell aggregates.

CONCLUSIONS

We could demonstrate for the first time that the expression of MMR is significantly upregulated in NP compared to patients with CS without NP or turbinate tissue of controls. Macrophages expressing MMR, accumulated in cell aggregates in NPs, play a possible key role in pathogen-macrophage interaction in NP disease.

Diagnostic relevance of Langerin detection in cells from bronchoalveolar lavage of patients with pulmonary Langerhans cell histiocytosis, sarcoidosis and idiopathic pulmonary fibrosis

The diagnosis of pulmonary Langerhans cell histiocytosis might be refined by demonstrating reliability of a new cell marker, i.e., Langerin (CD207), used on bronchoalveolar lavage fluid. For this purpose, we collected material from patients with this disease and also with sarcoidosis and idiopathic pulmonary fibrosis as controls. In addition to the immunocytochemical detection of Langerin, we examined the expression profiles of CD1a and the macrophage tandem-repeat mannose receptor (CD206). To test accessibility of Langerin, a C-type lectin, for mannosides, we employed reverse lectin histochemistry using mannose-containing neoglycoproteins. The analysis revealed a significantly increased percentage of CD1a- and Langerin-positive cells in pulmonary Langerhans cell histiocytosis in comparison with both other studied diseases. No expression of the 175-kDa mannose-binding lectin (CD206) in Langerhans cells was observed. Evidently, binding sites on the cells were not accessible for the mannose-containing neoglycoligand. These results provide evidence for the usefulness of Langerin-directed immuno- and glycohistochemical monitoring of bronchoalveolar lavage fluid in the diagnosis of pulmonary Langerhans cell histiocytosis.

Mannose receptor (MR) and common lymphatic endothelial and vascular endothelial receptor (CLEVER)-1 direct the binding of cancer cells to the lymph vessel endothelium

Although approximately 50% of cancers give rise to metastases via the lymphatic system, the mechanisms mediating this process have remained unknown. In this study, we have investigated the role of two lymphatic endothelial molecules, the mannose receptor (MR) and common lymphatic endothelial and vascular endothelial receptor (CLEVER)-1 in adhesion of malignant cells to the lymphatic endothelium, and analyzed their expression in two clinical series consisting of squamous cell cancers of the head and neck (n = 17) and breast cancers (n = 72). Affinity of the tested head and neck cancer cell lines to the lymphatic endothelium varied greatly, but adhesion of all cell lines was dependent on both the MR and CLEVER-1. Almost all cancer specimens contained peritumoral vessels that expressed CLEVER-1 and MR, and also the intratumoral lymph vessels often expressed them in both tumor types. However, only intratumoral expression of these molecules seems to be essential for metastatic spread to the regional lymph nodes. Only 8 (22%) of the 36 axillary node-negative breast carcinomas expressed the MR on the intratumoral lymph vessels as compared with 16 (50%) of the 32 node-positive carcinomas (P = 0.017), and all eight head and neck carcinoma patients with regional lymph node metastases at diagnosis had tumors that expressed CLEVER-1 on the intratumoral lymph vessels. These data suggest a role for both the MR and CLEVER-1 in directing the traffic of cancer cells within the lymphatic system.

[Study on transgenic elite indica container line D297B containing foreign insect-resistant gene gna]

It was reported in this article that the transgenic elite indica container line D297B containing snowdrop lectin (Galanthus nivalis agglutinin, GNA) gene gna was obtained by biolisties. PCR, Southern blotting and Western blotting indicated that the transgenes were integrated into the genome of D297B and expressed in transgenic plants. Analysis of protein activity showed that product of transgene had activity of agglutinin. Resistance of transgenic seeds to Hygromycin B suggested that the transgenes were integrated in a single locus and inherited according to the pattern of 3:1 in most of transgenic plants. In addition, the PCR analysis revealed that the insect-resistant gene gna and selective marker gene hpt were co-integrated and co-inherited.

Downregulation of urokinase plasminogen activator receptor expression inhibits Erk signalling with concomitant suppression of invasiveness due to loss of uPAR-beta1 integrin complex in colon cancer cells

Cancer invasion is regulated by cell surface proteinases and adhesion molecules. Interaction between specific cell surface molecules such as urokinase plasminogen activator receptor (uPAR) and integrins is crucial for tumour invasion and metastasis. In this study, we examined whether uPAR and beta1 integrin form a functional complex to mediate signalling required for tumour invasion. We assessed the expression of uPAR/beta1 integrin complex, Erk signalling pathway, adhesion, uPA and matrix metalloproteinase (MMP) expression, migration/invasion and matrix degradation in a colon cancer cell line in which uPAR expression was modified. Antisense inhibition of the cell surface expression of uPAR by 50% in human colon carcinoma HCT116 cells (A/S) suppressed Erk-MAP kinase activity by two-fold. Urokinase plasminogen activator receptor antisense treatment of HCT116 cells was associated with a 1.3-fold inhibition of adhesion, approximately four-fold suppression of HMW-uPA secretion and inhibition of pro-MMP-9 secretion. At a functional level, uPAR antisense resulted in a four-fold decline in migration/invasion and abatement of plasmin-mediated matrix degradation. In empty vector-transfected cells (mock), uPA strongly elevated basal Erk activation. In contrast, in A/S cells, uPA induction of Erk activation was not observed. Urokinase plasminogen activator receptor associated with beta1 integrin in mock-transfected cells. Disruption of uPAR-beta1 integrin complex in mock-transfected cells with a specific peptide (P25) inhibited uPA-mediated Erk-MAP kinase pathway and inhibited migration/invasion and plasmin-dependent matrix degradation through suppression of pro-MMP-9/MMP-2 expression. This novel paradigm of uPAR-integrin signalling may afford opportunities for alternative therapeutic strategies for the treatment of cancer.

Expression and Purification of a Novel Mannose-Binding Lectin From Pinellia ternata

Pinellia ternata agglutinin (PTA) from the tubers of P. ternata is a monocot mannose-binding lectin that catalytically agglutinated rabbit erythrocytes. The potential effect of PTA has gained considerable interest in recent years owing to clinical use of native PTA as the preparation against cancer and for plant protection against insect pests. Here we report a successful strategy to allow high-level expression of PTA as inclusion bodies in Escherichia coli M15. Purification of refolded recombinant protein from solubilized inclusion bodies by Ni-NTA agarose affinity chromatography yielded biological activity recombinant PTA (final yield of about 10 mg/L). The recombinant PTA agglutinated rabbit erythrocytes to a dilution similar to that determined for "native" lectin purified from P. ternata. The expression and purification system makes it possible to obtain sufficient quantities of biologically active and homogenous recombinant PTA sufficient to carry out advanced clinical trials. This is the first report on the large-scale expression and purification of biologically active recombinant PTA from E. coli.