Human peripheral blood mononuclear cells display a temporal evolving inflammatory profile after myocardial infarction and modify myocardial fibroblasts phenotype

Pathophysiological response after acute myocardial infarction (AMI) is described as a three-stage model involving temporal phenotypic modifications of both immune cells and fibroblasts: a primary inflammatory phase, followed by a reparative phase and a fibrous scar maturation phase. Purinergic receptors, particularly the P2Y11 receptor, have been reported to be involved in the regulation of inflammation after ischemia and could act for the resolution of inflammation after AMI. For the first time, we characterized the immuno-inflammatory and P2Y11 expression profiles of peripheral blood mononuclear cells (PBMC) from AMI patients and analyzed the consequences of presenting these cells to cardiac fibroblasts in vitro. PBMC from 178 patients were collected at various times after reperfused ST-segment elevation AMI, from H0 to M12. Expression level of P2RY11 and genes involved in tolerogenic profile of dendritic cells and T cell polarization were evaluated by RT-PCR. P2Y11 protein expression was assessed by flow cytometry. PBMC and human cardiac fibroblasts (HCF) were cocultured and α-SMA/vimentin ratio was analyzed by flow cytometry. Within the first 48 h after AMI, expression levels of HMOX1, STAT3 and CD4 increased while IDO1 and TBX21/GATA3 ratio decreased. Concomitantly, the expression of P2RY11 increased in both T and B cells. In vitro, PBMC collected at H48 after AMI induced an increase in α-SMA/vimentin ratio in HCF. Our results suggest that human PBMC display an evolving inflammatory profile with reparative characteristics the first two days after AMI and secrete soluble mediators leading to the fibroblastic proteins modification, thus participating to myocardial fibrosis.

Constitutive and induced forms of membrane-bound proteinase 3 interact with antineutrophil cytoplasmic antibodies and promote immune activation of neutrophils

Proteinase 3 (PR3) is the main target antigen of anti-neutrophil cytoplasmic antibodies (ANCA) in PR3-ANCA-associated vasculitis. A small fraction of PR3 is constitutively exposed on the surface of quiescent blood neutrophils in a proteolytically inactive form. When activated, neutrophils expose an induced form of membrane-bound PR3 (PR3^mb) on their surface as well, which is enzymatically less active than unbound PR3 in solution due to its altered conformation. In this work, our objective was to understand the respective role of constitutive and induced PR3^mb in the immune activation of neutrophils triggered by murine anti-PR3 mAbs and human PR3-ANCA. We quantified immune activation of neutrophils by the measurement of the production of superoxide anions and secreted protease activity in the cell supernatant before and after treatment of the cells by alpha-1 protease inhibitor (α1PI) that clears induced PR3^mb from the cell surface. Incubation of TNFα-primed neutrophils with anti-PR3 antibodies resulted in a significant increase in superoxide anion production, membrane activation marker exposition, and secreted protease activity. When primed neutrophils were first treated with α1PI, we observed a partial reduction in antibody-induced neutrophil activation, suggesting that constitutive PR3^mb is sufficient to activate neutrophils. The pre-treatment of primed neutrophils with purified antigen-binding fragments used as competitor significantly reduced cell activation by whole antibodies. This led us to the conclusion that PR3^mb promoted immune activation of neutrophils. We propose that blocking and/or elimination of PR3^mb offers a new therapeutic strategy to attenuate neutrophil activation in patients with PR3-ANCA-associated vasculitis.

High extracellular sodium chloride concentrations induce resistance to LPS signal in human dendritic cells

Recent evidence showed that in response to elevated sodium dietary intakes, many body tissues retain Na⁺ ions for long periods of time and can reach concentrations up to 200 mM. This could modulate the immune system and be responsible for several diseases. However, studies brought contrasted results and the effects of external sodium on human dendritic cell (DC) responses to danger signals remain largely unknown. Considering their central role in triggering T cell response, we tested how NaCl-enriched medium influences human DCs properties. We found that DCs submitted to high extracellular Na⁺ concentrations up to 200 mM remain viable and maintain the expression of specific DC markers, however, their maturation, chemotaxis toward CCL19, production of pro-inflammatory cytokines and ROS in response to LPS were also partially inhibited. In line with these results, the T-cell allostimulatory capacity of DCs was also inhibited. Finally, our data indicate that high NaCl concentrations triggered the phosphorylation of SGK1 and ERK1/2 kinases. These results raised the possibility that the previously reported pro-inflammatory effects of high NaCl concentrations on T cells might be counterbalanced by a downregulation of DC activation.

Voltage-Gated Sodium Channel NaV1.5 Controls NHE-1-Dependent Invasive Properties in Colon Cancer Cells

Colorectal cancer (CRC) is the second leading cause of death worldwide, with 0.9 million deaths per year. The metastatic stage of the disease is identified in about 20% of cases at the first diagnosis and is associated with low patient-survival rates. Voltage-gated sodium channels (Na_V) are abnormally overexpressed in several carcinomas including CRC and are strongly associated with the metastatic behavior of cancer cells. Acidification of the extracellular space by Na⁺/H⁺ exchangers (NHE) contributes to extracellular matrix degradation and cell invasiveness. In this study, we assessed the expression levels of pore-forming α-subunits of Na_V channels and NHE exchangers in tumor and adjacent non-malignant tissues from colorectal cancer patients, CRC cell lines and primary tumor cells. In all cases, SCN5A (gene encoding for Na_V1.5) was overexpressed and positively correlated with cancer stage and poor survival prognosis for patients. In addition, we identified an anatomical differential expression of SCN5A and SLC9A1 (gene encoding for NHE-1) being particularly relevant for tumors that originated on the sigmoid colon epithelium. The functional activity of Na_V1.5 channels was characterized in CRC cell lines and the primary cells of colon tumors obtained using tumor explant methodologies. Furthermore, we assessed the performance of two new small-molecule Na_V1.5 inhibitors on the reduction of sodium currents, as well as showed that silencing SCN5A and SLC9A1 substantially reduced the 2D invasive capabilities of cancer cells. Thus, our findings show that both Na_V1.5 and NHE-1 represent two promising targetable membrane proteins against the metastatic progression of CRC.

Immuno-inflammatory response in patients after myocardial infarction and involvement in fibrosis in vitro

Background

Pathophysiology of acute myocardial infarction (AMI) has been described in mice and is based on a three-stage model involving temporal modifications of immune cells and fibroblasts. The acute inflammatory phase is followed by a reparative phase and fibrous scar maturation phase. Purinergic signaling, particularly P2Y11 receptor, has been reported to be involved in the regulation of inflammation after ischemia and could be an actor of resolution of inflammation after AMI.

Purpose

The aims of our study were: (1) to characterize the immune and P2Y11R profiles of AMI patients and (2) to analyze interactions between patients' immune cells and cardiac fibroblasts in vitro.

Methods

We collected peripheral blood mononuclear cells (PBMC) of 182 patients at various times (H0, H4, H24, H48, D3, M1, M6, M12) after reperfused ST-segment elevation AMI, and of 30 healthy donors. Expression level of genes involved in tolerogenicity profile of dendritic cells (HMOX1, STAT3, IDO1), in T cell polarization (CD4, FOXP3, TBX21/GATA3) as well as P2RY11 were evaluated by RT-PCR. P2Y11R expression was analyzed using flow cytometry. PBMC and human cardiac fibroblasts (HCF) were co-cultured during one day (5PBMC/1 HCF) and gene level expression (ACTA2/VIM, COL1A1), phenotype (α-SMA/vimentin) and secretory (soluble collagen) profiles were analyzed by RT-PCR, flow cytometry and Sircol assay.

Results

In the first 48 hours after AMI, the expression level of HMOX1 (fold-change = 8.478 at H48, p<0.0001), STAT3 (2.856 at H0, p=0.0027) and CD4 increased (2.451 at H48, p=0.0052); IDO1 (0.2055 at H24, p<0.0001) and TBX21/GATA3 ratio decreased (0.4498 at H48, p=0.0026); FOXP3 did not vary significantly. In the same time, the expression level of P2RY11 increased (2.124 at H0, p=0.0015) as well as protein expression in T cells (median MFI = 845.5 at H0 vs 229.5 for healthy donors, p=0.0375). In vitro, we observed a non-significant increase of ACTA2/VIM ratio in HCF co-cultured with H24, M1, M6 PBMC; of α-SMA/vimentin with H48, M12 PBMC; of COL1A1 with H24, H48, M12 PBMC; and of soluble collagen in coculture supernatant with M1 PBMC.

Conclusion

Our results suggest that P2Y11R could be involved in evolution of immune response after AMI, and that, in the first 2 days, circulating immune cells have a reparative profile and could participate in the transformation of fibroblast into myofibroblasts.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Fondation pour la recherche médicale

The envelope protein of Zika virus interacts with apolipoprotein E early in the infectious cycle and this interaction is conserved on the secreted viral particles

Background

Zika virus (ZIKV), a member of the Flaviviridae family, has caused massive outbreaks of infection in tropical areas over the last decade and has now begun spreading to temperate countries. Little is currently known about the specific host factors involved in the intracellular life cycle of ZIKV. Flaviviridae viruses interact closely with host-cell lipid metabolism and associated secretory pathways. Another Flaviviridae, hepatitis C virus, is highly dependent on apolipoprotein E (ApoE) for the completion of its infectious cycle. We therefore investigated whether ZIKV also interacted with this protein.

Methods

ZIKV infections were performed on both liver and microglia derived cell lines in order to proceed to colocalization analysis and immunoprecipitation assays of ApoE and Zika envelope glycoprotein (Zika E). Transmission electron microscopy combined to immunogold labeling was also performed on the infected cells and related supernatant to study the association of ApoE and Zika E protein in the virus-induced membrane rearrangements and secreted particles, respectively. Finally, the potential of neutralization of anti-ApoE antibodies on ZIKV particles was studied.

Result

We demonstrated an interaction between ApoE and the Zika E protein. This specific interaction was observed in virus-induced host-cell membrane rearrangements, but also on newly formed intracellular particles. The partial neutralizing effect of anti-ApoE antibody and the immunogold labeling of the two proteins on secreted virions indicates that this interaction is conserved during ZIKV intracellular trafficking and release.

Conclusions

These data suggest that another member of the Flaviviridae also interacts with ApoE, indicating that this could be a common mechanism for the viruses from this family.

Quantitative analysis of the formation of nucleoprotein complexes between HIV-1 Gag protein and genomic RNA using transmission electron microscopy

In HIV, the polyprotein precursor Gag orchestrates the formation of the viral capsid. In the current view of this viral assembly, Gag forms low-order oligomers that bind to the viral genomic RNA triggering the formation of high-ordered ribonucleoprotein complexes. However, this assembly model was established using biochemical or imaging methods that do not describe the cellular location hosting Gag-gRNA complex nor distinguish gRNA packaging in single particles. Here, we studied the intracellular localization of these complexes by electron microscopy and monitored the distances between the two partners by morphometric analysis of gold beads specifically labeling Gag and gRNA. We found that formation of these viral clusters occurred shortly after the nuclear export of the gRNA. During their transport to the plasma membrane, the distance between Gag and gRNA decreases together with an increase of gRNA packaging. Point mutations in the zinc finger patterns of the nucleocapsid domain of Gag caused an increase in the distance between Gag and gRNA as well as a sharp decrease of gRNA packaged into virions. Finally, we show that removal of stem loop 1 of the 5'-untranslated region does not interfere with gRNA packaging, whereas combined with the removal of stem loop 3 is sufficient to decrease but not abolish Gag-gRNA cluster formation and gRNA packaging. In conclusion, this morphometric analysis of Gag-gRNA cluster formation sheds new light on HIV-1 assembly that can be used to describe at nanoscale resolution other viral assembly steps involving RNA or protein-protein interactions.

The Voltage-Gated Sodium Channel Beta4 Subunit Maintains Epithelial Phenotype in Mammary Cells

The SCN4B gene, coding for the Na_Vβ4 subunit of voltage-gated sodium channels, was recently found to be expressed in normal epithelial cells and down-regulated in several cancers. However, its function in normal epithelial cells has not been characterized. In this study, we demonstrated that reducing Na_Vβ4 expression in MCF10A non-cancer mammary epithelial cells generated important morphological changes observed both in two-dimensional cultures and in three-dimensional cysts. Most notably, the loss of Na_Vβ4 induced a complete loss of epithelial organisation in cysts and increased proteolytic activity towards the extracellular matrix. Loss of epithelial morphology was associated with an increased degradation of β-catenin, reduced E-cadherin expression and induction of mesenchymal markers N-cadherin, vimentin, and α-SMA expression. Overall, our results suggest that Navβ4 may participate in the maintenance of the epithelial phenotype in mammary cells and that its downregulation might be a determining step in early carcinogenesis.

Pathogenicity of Proteinase 3-Anti-Neutrophil Cytoplasmic Antibody in Granulomatosis With Polyangiitis: Implications as Biomarker and Future Therapies

Granulomatosis with polyangiitis (GPA) is a rare but serious necrotizing auto-immune vasculitis. GPA is mostly associated with the presence of Anti-Neutrophil Cytoplasmic Antibody (ANCA) targeting proteinase 3 (PR3-ANCA), a serine protease contained in neutrophil granules but also exposed at the membrane. PR3-ANCAs have a proven fundamental role in GPA: they bind neutrophils allowing their auto-immune activation responsible for vasculitis lesions. PR3-ANCAs bind neutrophil surface on the one hand by their Fab binding PR3 and on the other by their Fc binding Fc gamma receptors. Despite current therapies, GPA is still a serious disease with an important mortality and a high risk of relapse. Furthermore, although PR3-ANCAs are a consistent biomarker for GPA diagnosis, relapse management currently based on their level is inconsistent. Indeed, PR3-ANCA level is not correlated with disease activity in 25% of patients suggesting that not all PR3-ANCAs are pathogenic. Therefore, the development of new biomarkers to evaluate disease activity and predict relapse and new therapies is necessary. Understanding factors influencing PR3-ANCA pathogenicity, i.e. their potential to induce auto-immune activation of neutrophils, offers interesting perspectives in order to improve GPA management. Most relevant factors influencing PR3-ANCA pathogenicity are involved in their interaction with neutrophils: level of PR3 autoantigen at neutrophil surface, epitope of PR3 recognized by PR3-ANCA, isotype and glycosylation of PR3-ANCA. We detailed in this review the advances in understanding these factors influencing PR3-ANCA pathogenicity in order to use them as biomarkers and develop new therapies in GPA as part of a personalized approach.

4C3 Human Monoclonal Antibody: A Proof of Concept for Non-pathogenic Proteinase 3 Anti-neutrophil Cytoplasmic Antibodies in Granulomatosis With Polyangiitis

Granulomatosis with polyangiitis (GPA) is a severe autoimmune vasculitis associated with the presence of anti-neutrophil cytoplasmic antibodies (ANCA) mainly targeting proteinase 3 (PR3), a neutrophilic serine proteinase. PR3-ANCA binding to membrane-bound PR3 on neutrophils induce their auto-immune activation responsible for vascular lesions. However, the correlation between PR3-ANCA level and disease activity remains inconsistent, suggesting the existence of non-pathogenic PR3-ANCA. In order to prove their existence, we immortalized B lymphocytes from blood samples of GPA patients in remission having persistent PR3-ANCA to isolate non-activating PR3-ANCA. We obtained for the first time a non-activating human IgG1κ anti-PR3 monoclonal antibody (mAb) named 4C3. This new mAb binds soluble PR3 with a high affinity and membrane-bound PR3 on an epitope close to the PR3 hydrophobic patch and in the vicinity of the active site. 4C3 is able to bind FcγRIIA and FcγRIIIB and has a G2F glycosylation profile on asparagine 297. 4C3 did not induce activation of neutrophils and could inhibit human polyclonal PR3-ANCA-induced activation suggesting that 4C3 is non-pathogenic. This characteristic relies on the recognized epitope on PR3 rather than to the Fc portion properties. The existence of non-pathogenic PR3-ANCA, which do not activate neutrophils, could explain the persistence of high PR3-ANCA levels in some GPA patients in remission and why PR3-ANCA would not predict relapse. Finally, these results offer promising perspectives particularly regarding the understanding of PR3-ANCA pathogenicity and the development of new diagnostic and therapeutic strategies in GPA.

Rock inhibition promotes NaV1.5 sodium channel-dependent SW620 colon cancer cell invasiveness

The acquisition of invasive capacities by carcinoma cells, i.e. their ability to migrate through and to remodel extracellular matrices, is a determinant process leading to their dissemination and to the development of metastases. these cancer cell properties have often been associated with an increased Rho-ROCK signalling, and ROCK inhibitors have been proposed for anticancer therapies. In this study we used the selective ROCK inhibitor, Y-27632, to address the participation of the Rho-ROCK signalling pathway in the invasive properties of SW620 human colon cancer cells. Contrarily to initial assumptions, Y-27632 induced the acquisition of a pro-migratory cell phenotype and increased cancer cell invasiveness in both 3- and 2-dimensions assays. This effect was also obtained using the other ROCK inhibitor Fasudil as well as with knocking down the expression of ROCK-1 or ROCK-2, but was prevented by the inhibition of Na_V1.5 voltage-gated sodium channel activity. Indeed, ROCK inhibition enhanced the activity of the pro-invasive Na_V1.5 channel through a pathway that was independent of gene expression regulation. In conclusions, our evidence identifies voltage-gated sodium channels as new targets of the ROCK signalling pathway, as well as responsible for possible deleterious effects of the use of ROCK inhibitors in the treatment of cancers.

BAY 41-4109-mediated aggregation of assembled and misassembled HBV capsids in cells revealed by electron microscopy

HBc is a small protein essential for the formation of the icosahedral HBV capsid. Its multiple roles in the replication cycle make this protein a promising target for the development of antiviral molecules. Based on the structure of HBc, a series of HBV assembly inhibitors, also known as capsid assembly modulators, were identified. We investigated the effect of BAY 41-4109, a heteroaryldihydropyrimidine derivative that promotes the assembly of a non-capsid polymer. We showed, by confocal microscopy, that BAY 41-4109 mediated HBc aggregation, mostly in the cytoplasm of Huh7 cells. Image analysis revealed that aggregate size depended on BAY 41-4109 concentration and treatment duration. Large aggregates in the vicinity of the nucleus were enclosed by invaginations of the nuclear envelope. This deformation of the nuclear envelope was confirmed by transmission electron microscopy (TEM) and immuno-TEM. These two techniques also revealed that the HBc aggregates were accumulations of capsid-like shells with an electron-dense material consisting of HBV core fragments. These findings, shedding light on the ultrastructural organization of HBc aggregates, provide insight into the mechanisms of action of BAY 41-4109 against HBV and will serve as a basis for comparison with other HBV capsid assembly inhibitors.

CMV-infected kidney grafts drive the expansion of blood-borne CMV-specific T cells restricted by shared class I HLA molecules via presentation on donor cells

We aimed to determine the role of cytomegalovirus (CMV)-infected donor cells in the development of a CMV-specific immune response in kidney transplant recipients. We assessed the CMV pp65-specific immune response by using interferon-ɣ ELISPOT and dextramers in peripheral blood mononuclear cells from 115 recipients (D+R- 31, D+R + 44, D-R + 40) late after transplantation (mean 59 ± 42 months). Receiving a kidney from a D+ donor resulted in a higher number of IFN-ɣ-producing anti-CMV T cells (P = .004). This effect disappeared with the absence of shared HLA class I specificities between donors and recipients (P = .430). To confirm the role of donor cells in stimulating the expansion of newly developed CMV-specific CD8⁺ T cells after transplantation, we compared the number of HLA-A2-restricted CMV-specific CD8⁺ T cells in primo-infected recipients who received an HLA-A2 or non-HLA-A2 graft. The median of anti-CMV pp65 T cells restricted by HLA-A2 was very low for patients who received a non-HLA-A2 graft vs an HLA-A2 graft (300 [0-14638] vs. 17972 [222-85594] anti-CMV pp65 CD8⁺ T cells/million CD8⁺ T cells, P = .001). This adds new evidence that CMV-infected kidney donor cells present CMV peptides and drive an inflation of memory CMV-specific CD8⁺ T cells, likely because of frequent CMV replications within the graft.

Sulla carnosa modulates root invertase activity in response to the inhibition of long-distance sucrose transport under magnesium deficiency

Being the principal product of photosynthesis, sucrose is involved in many metabolic processes in plants. As magnesium (Mg) is phloem mobile, an inverse relationship between Mg shortage and sugar accumulation in leaves is often observed. Mg deficiency effects on carbohydrate contents and invertase activities were determined in Sulla carnosa Desf. Plants were grown hydroponically at different Mg concentrations (0.00, 0.01, 0.05 and 1.50 mM Mg) for one month. Mineral analysis showed that Mg contents were drastically diminished in shoots and roots mainly at 0.01 and 0.00 mM Mg. This decline was adversely associated with a significant increase of sucrose, fructose and mainly glucose in shoots of plants exposed to severe deficiency. By contrast, sugar contents were severely reduced in roots of these plants indicating an alteration of carbohydrate partitioning between shoots and roots of Mg-deficient plants. Cell wall invertase activity was highly enhanced in roots of Mg-deficient plants, while the vacuolar invertase activity was reduced at 0.00 mM Mg. This decrease of vacuolar invertase activity may indicate the sensibility of roots to Mg starvation resulting from sucrose transport inhibition. ¹⁴ CO₂ labeling experiments were in accordance with these findings showing an inhibition of sucrose transport from source leaves to sink tissues (roots) under Mg depletion. The obtained results confirm previous findings about Mg involvement in photosynthate loading into phloem and add new insights into mechanisms evolved by S. carnosa to cope with Mg shortage in particular the increase of the activity of cell wall invertase.

Sulla carnosa modulates root invertase activity in response to the inhibition of long-distance sucrose transport under magnesium deficiency

Being the principal product of photosynthesis, sucrose is involved in many metabolic processes in plants. As magnesium (Mg) is phloem mobile, an inverse relationship between Mg shortage and sugar accumulation in leaves is often observed. Mg deficiency effects on carbohydrate contents and invertase activities were determined in Sulla carnosa Desf. Plants were grown hydroponically at different Mg concentrations (0.00, 0.01, 0.05 and 1.50 mM Mg) for one month. Mineral analysis showed that Mg contents were drastically diminished in shoots and roots mainly at 0.01 and 0.00 mM Mg. This decline was adversely associated with a significant increase of sucrose, fructose and mainly glucose in shoots of plants exposed to severe deficiency. By contrast, sugar contents were severely reduced in roots of these plants indicating an alteration of carbohydrate partitioning between shoots and roots of Mg-deficient plants. Cell wall invertase activity was highly enhanced in roots of Mg-deficient plants, while the vacuolar invertase activity was reduced at 0.00 mM Mg. This decrease of vacuolar invertase activity may indicate the sensibility of roots to Mg starvation resulting from sucrose transport inhibition. ¹⁴ CO₂ labeling experiments were in accordance with these findings showing an inhibition of sucrose transport from source leaves to sink tissues (roots) under Mg depletion. The obtained results confirm previous findings about Mg involvement in photosynthate loading into phloem and add new insights into mechanisms evolved by S. carnosa to cope with Mg shortage in particular the increase of the activity of cell wall invertase.

Immune deficiency-related enteropathy-lymphocytopenia-alopecia syndrome results from tetratricopeptide repeat domain 7A deficiency

BACKGROUND

Inflammatory bowel disease (IBD) is one of the most common chronic gastrointestinal diseases, but the underlying molecular mechanisms remain largely unknown. Studies of monogenic diseases can provide insight into the pathogenesis of IBD.

OBJECTIVE

We thought to determine the underlying molecular causes of IBD occurring in 2 unrelated families in association with an immune deficiency.

METHODS

We performed genetic linkage analysis and candidate gene sequencing on 13 patients from a large consanguineous family affected by early-onset IBD, progressive immune deficiency, and, in some cases, autoimmunity and alopecia, a condition we named enteropathy-lymphocytopenia-alopecia. The candidate gene was also sequenced in an unrelated patient with a similar phenotype. We performed histologic analysis of patients' intestinal biopsy specimens and carried out functional assays on PBMCs. Gut organoids derived from a patient's biopsy specimen were analyzed.

RESULTS

We identified biallelic missense mutations in tetratricopeptide repeat domain 7A (TTC7A) in all patients from both families. The resulting TTC7A depletion modified the proliferation, adhesion, and migratory capacities of lymphocytes through inappropriate activation of the RhoA signaling pathway. Normal function was restored by wild-type TTC7A expression or addition of a RhoA kinase inhibitor. The growth and polarity of gut epithelial organoids were also found to be dependent on the RhoA signaling pathway.

CONCLUSIONS

We show that TTC7A regulates the actin cytoskeleton dynamics in lymphocytes through the RhoA signaling pathway and is required in both lymphocytes and epithelial cells for maintaining equilibrium between cell proliferation, migration, polarization, and cell death. Our study highlights variability in the phenotypic expression resulting from TTC7A deficiency and outlines that impairment of both epithelial cells and lymphocytes cooperatively causes IBD.

IL-2 phosphorylates STAT5 to drive IFN-γ production and activation of human dendritic cells

Human dendritic cells (hDCs) produce IL-2 and express IL-2R α-chain (CD25), but the role of IL-2 in DC functions is not well defined. A recent study suggested that the main function of CD25 on hDCs was to transpresent IL-2 to activate T lymphocytes. Our results demonstrate the expression of the three chains of the IL-2R on hDCs and that IL-2 induces STAT5 phosphorylation. Interestingly, use of inhibitors of p-STAT5 revealed that IL-2 increases LPS-induced IFN-γ through STAT5 phosphorylation. Finally, we report that IL-2 increases the ability of hDCs to activate helpless CD8(+) T cells, most likely because of IL-2-triggered IFN-γ synthesis, as we previously described. For the first time, to our knowledge, we disclose that IL-2 induces monocyte-derived hDC's functional maturation and activation through IL-2R binding. Interestingly, our study suggests a direct effect of anti-CD25 mAbs on hDCs that may contribute to their clinical efficacy.

TTC7A mutations disrupt intestinal epithelial apicobasal polarity

Multiple intestinal atresia (MIA) is a rare cause of bowel obstruction that is sometimes associated with a combined immunodeficiency (CID), leading to increased susceptibility to infections. The factors underlying this rare disease are poorly understood. We characterized the immunological and intestinal features of 6 unrelated MIA-CID patients. All patients displayed a profound, generalized lymphocytopenia, with few lymphocytes present in the lymph nodes. The thymus was hypoplastic and exhibited an abnormal distribution of epithelial cells. Patients also had profound disruption of the epithelial barrier along the entire gastrointestinal tract. Using linkage analysis and whole-exome sequencing, we identified 10 mutations in tetratricopeptide repeat domain–7A (TTC7A), all of which potentially abrogate TTC7A expression. Intestinal organoid cultures from patient biopsies displayed an inversion of apicobasal polarity of the epithelial cells that was normalized by pharmacological inhibition of Rho kinase. Our data indicate that TTC7A deficiency results in increased Rho kinase activity, which disrupts polarity, growth, and differentiation of intestinal epithelial cells, and which impairs immune cell homeostasis, thereby promoting MIA-CID development.

Bifidobacteria BbC50 Fermentation Products Induce Human Cd4+ Regulatory T Cells with Antigen-Specific Activation and Bystander Suppression

Probiotic bacteria have been shown to have health benefits in various situations (inflammation, allergy, infection). We previously showed that a bacteria-free fermentation product of Bifidobacterium breve C50 (BbC50sn) induced high IL-10 secretion by human dendritic cells. As IL-10 is a regulatory cytokine, the aim of the present study was to examine whether DCs cultured in the presence of BbC50sn could induce regulatory T cells in an allogeneic context. Purified CD4+CD25− human T cells were co-cultured with allogeneic BbC50sn-treated dendritic cells for 4 weeks. The T cell population (BbC50sn-T) was analysed both at phenotypical and functional [ability to inhibit a mixed lymphocyte reaction (MLR)] levels. We showed that T lymphocytes acquired phenotype characteristics of regulatory T cells after 4 weeks of co-culture with BbC50sn-DCs, and inhibited in vitro T lymphocyte proliferation and IFN-γ production in an MLR. Transwell experiments demonstrated that this suppressive activity was not T cell contact-dependent but probably mediated by a soluble factor. Although BbC50sn-T cells secreted significant amounts of IL-10 and TGF-β, their suppressive effect is most likely not mediated through these cytokines. This is, to our knowledge, the first demonstration of in vitro regulatory T cell induction by a bacteria-free fermentation product in an allogeneic context.

Polymerase ε1 mutation in a human syndrome with facial dysmorphism, immunodeficiency, livedo, and short stature ("FILS syndrome")

Homozygous missense mutations in POLE1 caused an inherited disorder characterized by facial dysmorphism, immunodeficiency, livedo, and short stature.

DNA polymerase ε (Polε) is a large, four-subunit polymerase that is conserved throughout the eukaryotes. Its primary function is to synthesize DNA at the leading strand during replication. It is also involved in a wide variety of fundamental cellular processes, including cell cycle progression and DNA repair/recombination. Here, we report that a homozygous single base pair substitution in POLE1 (polymerase ε 1), encoding the catalytic subunit of Polε, caused facial dysmorphism, immunodeficiency, livedo, and short stature (“FILS syndrome”) in a large, consanguineous family. The mutation resulted in alternative splicing in the conserved region of intron 34, which strongly decreased protein expression of Polε1 and also to a lesser extent the Polε2 subunit. We observed impairment in proliferation and G1- to S-phase progression in patients’ T lymphocytes. Polε1 depletion also impaired G1- to S-phase progression in B lymphocytes, chondrocytes, and osteoblasts. Our results evidence the developmental impact of a Polε catalytic subunit deficiency in humans and its causal relationship with a newly recognized, inherited disorder.

Induction of human CD4+ regulatory T cells by mycophenolic acid-treated dendritic cells

Depending on their degree of maturation, costimulatory molecule expression, and cytokine secretion, dendritic cells (DC) can induce immunity or tolerance. DC treated with mycophenolic acid during their maturation (MPA-DC) have a regulatory phenotype and may therefore provide a new approach to induce allograft tolerance. Purified CD4(+) T cells stimulated in a human in vitro model of mixed culture by allogeneic MPA-DC displayed much weaker proliferation than T cells activated by mature DC and were anergic. This hyporesponsiveness was alloantigen-specific. Interestingly, T cells stimulated by MPA-DC during long-term coculture in four 7-day cycles displayed potent, suppressive activity, as revealed by marked inhibition of the proliferation of naive and preactivated control T cells. These regulatory T cells (Tregs) appeared to have antigen specificity and were contact-dependent. Tregs induced by MPA-DC were CD25(+)glucocorticoid-induced TNFR(+)CTLA-4(+)CD95(+), secreted IL-5 and large amounts of IL-10 and TGF-beta, and displayed enhanced forkhead box p3 expression. These results obtained in vitro demonstrate that human MPA-DC can induce allospecific Tregs that may be exploited in cell therapy to induce allograft tolerance.

Sentinel lymph node involvement and a high Breslow index are independent factors of risk for early relapse of melanoma

AIM

The clinical relevance of sentinel lymph node (SLN) analysis was evaluated prospectively and compared with other known risk factors of relapse in early stage melanoma.

METHODS

Surgery was guided by lymphoscintigraphy, blue dye and gamma probe detection. SLN were analysed by haematoxylin eosin (HE) histochemistry and multimarker immunohistochemistry (IHC). Disease free survival (DFS) was evaluated with Kaplan-Meier plots according to different parameters and Cox analyses of variance.

RESULTS

From 210 patients a total of 381 SLN were excised. Lymphoscintigraphy identified all excised SLN with only 2 false positive lymphatic lakes. Fifty patients (24%) had tumour positive SLN. With a mean follow-up of 31.3 months, 29 tumour recurrences were observed, 19 (38%) in 50 SLN positive and 10 (6%) in 160 SLN negative patients. Strong predictive factors for early relapse (p < 0.0005) were SLN positivity and a high Breslow index.

CONCLUSION

SLN tumour positivity is an independent factor of high risk for early relapse with a higher power of discrimination than the Breslow index.

Towards deciphering phloem: a transcriptome analysis of the phloem of Apium graveolens

Events occurring in the phloem tissue are key to understanding a wide range of developmental and physiological processes in vascular plants. While a considerable amount of molecular information on phloem proteins has emerged in the past decade, a unified picture of the molecular mechanisms involved in phloem differentiation and function is still lacking. New models to increase our understanding of this complex tissue can be created by the development of global approaches such as genomic analysis. In order to obtain a comprehensive overview of the molecular biology of the phloem tissue, we developed a genomic approach using Apium graveolens as a model. cDNA libraries were constructed from mRNAs extracted from isolated phloem of petioles. Expression data obtained from the analysis of 989 expressed sequence tags (ESTs) and the transcript profile deduced from a cDNA macroarray of 1326 clones were combined to identify genes showing distinct expression patterns in the vascular tissues. Comparisons of expression profiles obtained from the phloem, xylem and storage parenchyma tissues uncovered tissue-specific differential expression patterns for given sets of genes. The major classes of mRNAs predominantly found in the phloem encode proteins related to phloem structure, metal homeostasis or distribution, stress responses and degradation or turnover of proteins. Of great interest for future studies are the genes we found to be specifically expressed in the phloem but for which the function is still unknown, and also those genes described in previous reports to be up or downregulated by specific interactions. From a broader prospective, our results also clearly demonstrate that cDNA macroarray technology can be used to identify the key genes involved in various physiological and developmental processes in the phloem.

Pulmonary toxicity with mefloquine

This report presents a case of acute lung injury developing within hours after administration of mefloquine for a low-level Plasmodium falciparum malaria, which was persistent despite halofantrine therapy. Extensive microbiological investigation remained negative and video-assisted thoracoscopic lung biopsy demonstrated diffuse alveolar damage. The evolution was favourable without treatment. This is the second report of acute lung injury and diffuse alveolar damage caused by mefloquine. Glucose-6-phosphate dehydrogenase deficiency was present in the former case and was thought to contribute to the lung injury. However, glucose-phosphate dehydrogenase was normal in the present case, suggesting that it is not a predisposing condition to the lung injury.

Nasal vaccination with attenuated Salmonella typhimurium strains expressing the Hepatitis B nucleocapsid: dose response analysis

Nasal vaccination of mice with recombinant attenuated strains of Salmonella typhimurium is more efficient at inducing antibody responses than oral vaccination. However, mortality was observed when high doses [10(9) colony forming unit (CFU)], otherwise safe by the oral route, were administered. This observation was counterbalanced by the fact that nasal vaccination was still highly efficient with lower doses (10(6) CFU), which are inefficient by the oral route and this, without any incidents of mortality. Here, we further analyse in mice the effect of nasal vaccination with differently attenuated S. typhimurium strains expressing the Hepatitis B nucleocapsid (HBc). Surprisingly, as few as 100 CFU were sufficient to induce a maximal HBc specific antibody response, but only if the bacteria were inhaled. Furthermore, we observed no correlation between the inoculum dose and the number of surviving bacteria in cervical lymph nodes and spleen. Examination of lung sections revealed strong inflammation and bronchopneumonia 24 h after nasal vaccination with 10(8) CFU, while only minor signs of inflammation were detected transiently when 10(3) CFU or phosphate buffered saline (PBS) were administered. Our data suggest that the safety issue of nasal vaccination with low doses of the Salmonella vaccine strains should be addressed in humans, as it might be an efficient alternative to oral vaccination.

Identification of a mannitol transporter, AgMaT1, in celery phloem

A celery petiole phloem cDNA library was constructed and used to identify a cDNA that gives Saccharomyces cerevisiae cells the ability to grow on mannitol and transport radiolabeled mannitol in a manner consistent with a proton symport mechanism. This cDNA was named AgMaT1 (Apium graveolens mannitol transporter 1). The expression profile in source leaves and phloem was in agreement with a role for mannitol in phloem loading in celery. The identification in eukaryotes of a mannitol transporter is important because mannitol is not only a primary photosynthetic product in species such as celery but is also considered a compatible solute and antioxidant implicated in resistance to biotic and abiotic stress.

Cyclosporine toxicity in renal transplant recipients detected by nailfold capillaroscopy with Na-fluorescein

BACKGROUND

Cyclosporine represented a major advance in the medical management of patients with organ transplantation, but its use is limited by the frequent occurrence of hypertension and renal toxicity diagnosed by invasive renal biopsy. Renal histology shows a specific arteriolopathy. It was hypothesized that cyclosporine may also induce subclinical microvascular changes in the skin that might be detected noninvasively by a combination of dynamic capillaroscopy [capillary blood cell velocity (CBV)] with and without intravenous Na-fluorescein (NaF) injection and laser Doppler fluxmetry (LDF).

METHODS

The nailfold skin microcirculation was evaluated in 112 consecutive renal transplant recipients (54 +/- 11 years old; 70 males and 42 females) receiving cyclosporine. The investigation was made the same day as a routine renal biopsy performed in all patients more than two years after transplantation. Renal biopsies were blindly classified as positive (N = 33) when significant specific signs of cyclosporine toxicity were clearly observed (AH2-AH3) and were otherwise negative (AH0-AH1, N = 79) according to the Banff classification.

RESULTS

Time to fluorescence peak after NaF injection (tpNaF) was significantly longer in patients with positive biopsies than in patients with negative biopsies (13.9 +/- 8.1 vs. 17.5 +/- 9.4 sec, P = 0.009). All patients but three with negative biopsies (93%) had a tpNaF less than 10 seconds (sensitivity 91%, negative predictive value 93%). On the other hand, CBV, LDF, plasma levels of cyclosporine, and endothelin were similar in the two groups.

CONCLUSION

Nailfold fluorescence capillaroscopy is an accurate and simple mean to rule out cyclosporine toxicity in renal transplant recipients. A normal test could avoid invasive renal biopsy in about 40% of the patients. Renal biopsy would, however, still be indicated when the test is abnormal.

The safety of one, or repeated, vital capacity maneuvers during general anesthesia

A vital capacity maneuver (VCM) (inflating the lungs to 40 cm H(2)O for 15 s) is effective in relieving atelectasis during general anesthesia or after cardiopulmonary bypass (CPB). The study was undertaken to investigate the safety of one or repeated VCM. Five groups of six pigs were studied. Two groups had general anesthesia for 6 h and one group received a VCM every hour. Three other groups received CPB. VCM was performed after CPB in two of these groups. VCM was then repeated every hour in one of the groups. Lung damage was evaluated by extravascular lung water (EVLW) measurement, light microscopy, and the half-time (T(1/2)) of disappearance from the lung of a nebulized aerosol containing (99m)Tc-DTPA. No changes were noted in extravascular lung water. The pigs subjected to VCM decreased their T(1/2). In the groups exposed to repeated VCM, T(1/2) remained lowered (CPB pigs) or decreased over time (non-CPB pigs). No lung damage could be seen on the morphology study. These results suggest that one VCM is a safe procedure. The increase in lung clearance of (99m)Tc-DTPA not associated with an increase in lung water when VCM is repeated may have been caused by an increase in lung volume. Therefore, repeated VCM also appears to be safe.

IMPLICATIONS

This study demonstrates in an animal model that inflating the lung once or repeatedly to the vital capacity is a safe procedure. This maneuver, also called the vital capacity maneuver, can be used to relieve lung collapse which occurs in all patients during general anesthesia.

Sugar transporters in higher plants--a diversity of roles and complex regulation

Sugar-transport proteins play a crucial role in the cell-to-cell and long-distance distribution of sugars throughout the plant. In the past decade, genes encoding sugar transporters (or carriers) have been identified, functionally expressed in heterologous systems, and studied with respect to their spatial and temporal expression. Higher plants possess two distinct families of sugar carriers: the disaccharide transporters that primarily catalyse sucrose transport and the monosaccharide transporters that mediate the transport of a variable range of monosaccharides. The tissue and cellular expression pattern of the respective genes indicates their specific and sometimes unique physiological tasks. Some play a purely nutritional role and supply sugars to cells for growth and development, whereas others are involved in generating osmotic gradients required to drive mass flow or movement. Intriguingly, some carriers might be involved in signalling. Various levels of control regulate these sugar transporters during plant development and when the normal environment is perturbed. This article focuses on members of the monosaccharide transporter and disaccharide transporter families, providing details about their structure, function and regulation. The tissue and cellular distribution of these sugar transporters suggests that they have interesting physiological roles.

Sucrose transporters in plants: update on function and structure

In plants, sucrose is the major transport form for photoassimilated carbon and is both a source of carbon skeletons and energy for plant organs unable to perform photosynthesis (sink organs). As a molecule translocated over distance, sucrose has to pass through a number of membranes. Membrane transport of sucrose has therefore been considered for a long time as a major determinant of plant productivity. After several decades of physiological and biochemical experiments measuring the activity of sucrose carriers, unequivocal evidence came from the first identification of a cDNA coding a sucrose carrier (SoSUT1, Riesmeier et al. (1992) EMBO J. 11, 4705-4713). At present 20 different cDNAs encoding sucrose carriers have been identified in different plant species, in both dicots and monocots (one case). The total number is increasing rapidly and most importantly, it can be guessed from the results obtained for Arabidopsis, that in each species, sucrose transporters represent a gene family. The sequences are highly conserved and those carriers display the typical 12 transmembrane alpha-helices of members of the Major Facilitator superfamily. Yeast expression of those carriers indicate that they are all influx carriers, all cotransport sucrose and proton and that their affinity for sucrose is surprisingly similar (0.2-2 mM). All their characteristics are in agreement with those demonstrated at the physiological level in plants. These characteristics are discussed in relation to the function in plants and the few data available on the structure of those transporters in relation to their function are presented.

The sucrose transporter of celery. Identification and expression during salt stress

In celery (Apium graveolens L.), long-distance transport of reduced carbon occurs both in the form of sucrose (Suc) and mannitol. The presence of mannitol has been related to the resistance of celery to salt stress. To investigate the transport events occurring during salt stress, we have cloned the H(+)/Suc transporter of celery AgSUT1 (A. graveolens Suc uptake transport 1) from a mature leaf cDNA library. The function of the encoded protein was confirmed by expression in yeast. AgSUT1 is a H(+)/Suc transporter with a high affinity for Suc (K(m) of 139 microM). Another closely related cDNA (AgSUT2) was also identified. AgSUT1 is mainly expressed in mature leaves and phloem of petioles, but also in sink organs such as roots. When celery plants were subjected to salt stress conditions (30 d watering with 300 mM NaCl) favoring mannitol accumulation (J.D. Everard, R. Gucci, S.C. Kann, J.A. Flore, W.H. Loescher [1994] Plant Physiol 106: 281-292), AgSUT1 expression was decreased in all organs, but markedly in roots. The results are discussed in relation to the physiology of celery.

Cloning and expression of a hexose transporter gene expressed during the ripening of grape berry

The ripening of grape (Vitis vinifera L.) is characterized by massive sugar import into the berries. The events triggering this process and the pathways of assimilate transport are still poorly known. A genomic clone Vvht1 (Vitis vinifera hexose transporter1) and the corresponding cDNA encoding a hexose transporter whose expression is induced during berry ripening have been isolated. Vvht1 is expressed mainly in the berries, with a first peak of expression at anthesis, and a second peak about 5 weeks after véraison (a viniculture term for the inception of ripening). Vvht is strictly conserved between two grape cultivars (Pinot Noir and Ugni-Blanc). The organization of the Vvht1 genomic sequence is homologous to that of the Arabidopsis hexose transporter, but differs strongly from that of the Chlorella kessleri hexose transporter genes. The Vvht1 promoter sequence contains several potential regulating cis elements, including ethylene-, abscisic acid-, and sugar-responsive boxes. Comparison of the Vvht1 promoter with the promoter of grape alcohol dehydrogenase, which is expressed at the same time during ripening, also allowed the identification of a 15-bp consensus sequence, which suggests a possible co-regulation of the expression of these genes. The expression of Vvht1 during ripening indicates that sucrose is at least partially cleaved before uptake into the flesh cells.

Identification of a pollen-specific sucrose transporter-like protein NtSUT3 from tobacco

Pollen cells are symplasmically isolated during maturation and germination. Pollen therefore needs to take up nutrients via membrane carriers. Physiological measurements on pollen indicate sucrose transport in the pollen tube. A cDNA encoding a pollen-specific sucrose transporter-like protein NtSUT3 was isolated from a tobacco pollen cDNA library. NtSUT3 expression is detected only in pollen and is restricted to late pollen development, pollen germination and pollen tube growth. Altogether these data indicate that pollen is supplied not only with glucose, but also with sucrose through a specific sucrose transporter. The respective contribution of each transport pathway may change during pollen tube growth.

[Oligosaccharide sulfate inhibitors of selectin-sugar interactions in inflammatory processes]

Leucocyte migration into lymphatic tissues or inflammatory sites depends upon the expression of adhesion molecules. Among these molecules, the selectins expressed on endothelial cells (E- and P-selectins) and leucocytes (L-selectin) recognize carbohydrate ligands such as sialyl Lewis A or sialyl Lewis X oligosaccharides due to the same positioning of NeuAc, Gal and Fuc residues in both isomeric structures. We have shown that the sialic acid residue could be replaced by a sulfate group such as in the sulfated Lewis A pentasaccharide, one of the most potent monovalent ligand for human E-selectin, which was shown to be very active in the prevention of ischemia reperfusion lung injury. In the same way, we have prepared through chemoenzymatic syntheses, two disulfated Lewis X pentasaccharides, the sulfated analogs of carbohydrate ligands found on GLYCAM 1, the natural receptor of L-selectin. Finally, based on the double recognition of L-selectin with Lewis type and glycosaminoglycan structures, we tentatively introduced a possible link between the selectin- and the integrin-mediated lymphocyte adhesion systems.

Linkage of a major quantitative trait locus to Yaa gene-induced lupus-like nephritis in (NZW x C57BL/6)F1 mice

In the present study, we mapped the major quantitative trait loci (QTL) differing between the NZW and C57BL/6 inbred strains of mice by making use of (NZW x C57BL/6.Yaa)F1 mice, a model in which the lupus-like autoimmune syndrome observed in male mice is associated with the presence of an as yet unidentified Y chromosome-linked autoimmune acceleration gene, Yaa. Linkage analysis of 126 C57BL/6 x (NZW x C57BL/6.Yaa)F1 backcross males provided evidence for a major QTL on chromosome 7 controlling both the severity of glomerulonephritis and the production of IgG anti-DNA autoantibody and retroviral gp70-anti-gp70 immune complexes. Two additional QTL of C57BL/6 origin on chromosome 17 had no apparent individual effects, but showed strong epistatic interaction with chromosome 7 QTL for disease severity and anti-DNA autoantibody production. Our data also identified on chromosome 13 a QTL of NZW origin with a major effect on the level of gp70, and showing an additive effect with the chromosome 7 QTL on the level of gp70 immune complexes. Our study thus provides a model to dissect the complex genetic interactions that result in manifestations of murine lupus-like disease.

Colocalization of collagen overexpression and inflammatory cell infiltration in the two-kidney one-clip rat model from the early days of hypertension onward

In the first 6 days of hypertension, infiltrated mononuclear cells were colocalized with collagen (I) mRNA-overexpressing fibroblasts in the adventitial area of unclipped kidney. The number of adventitial infiltrated mononuclear cells was correlated with adventitial collagen (I) surface expansion. After 22 days of hypertension no collagen (I) mRNA-overexpressing fibroblasts or any increase in collagen area or mononuclear cell infiltration was observed. In the interstitium of unclipped kidney, collagen (I) mRNA overexpression, collagen (I) expansion and mononuclear cell infiltration began later, from the 7th day of hypertension, and kept increasing. In the clipped kidney, after expansion in the first 6 days of hypertension, the adventitial collagen remained stable. These results suggest that in the unclipped kidney fibroblastic activation begins within the first 6 days of hypertension in the adventitial area, but is transient, and fibrosis then spreads in the interstitium. Mononuclear cell infiltration is colocalized and correlated with adventitial and interstitial fibrosis. In the first 6 days, hypertension is not the only cause of fibrosis; the same level of adventitial fibrosis is detected in the nonhypertensive clipped kidney. All observed pathological phenomena could be detected within the first 3 days of hypertension.

Prevention of ischemia-reperfusion lung injury by sulfated Lewis(a) pentasaccharide. The Paris-Sud University Lung Transplantation Group

Inhibition of polymorphonuclear neutrophil (PMN) adhesion to the pulmonary endothelium attenuates ischemia-reperfusion (I/R) lung injury. We hypothesized that 3'-sulfated Lewis(a) (SuLa), a potent ligand for the selectin adhesion molecules, may have a beneficial effect on I/R lung injury, as measured by the filtration coefficient (K(fc)), and reduce pulmonary sequestration of PMN as assessed by the lung myeloperoxidase (MPO) activity. Blood-perfused rat lungs were subjected to 30 min of perfusion, 60 min of warm ischemia, and 90 min of reperfusion after treatment with either SuLa (200 microg) or saline. Effects of SuLa on PMN adhesion to cultured human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor-alpha and calcium ionophore were also investigated. Compared with preischemia conditions, I/R induced a significant increase in K(fc), which was attenuated with SuLa (80 +/- 8 vs. 30 +/- 5%; P < 0.001). SuLa reduced lung MPO and PMN adhesion to stimulated HUVEC. These results indicate that SuLa reduces I/R-induced lung injury and PMN accumulation in lung. This protective effect might be related to inhibition of PMN adhesion to endothelial cells.

Macromolecular trafficking indicated by localization and turnover of sucrose transporters in enucleate sieve elements

The leaf sucrose transporter SUT1 is essential for phloem loading and long-distance transport of assimilates. Both SUT1 messenger RNA (mRNA) and protein were shown to be diurnally regulated and to have high turnover rates. SUT1 protein was detected by immunolocalization in plasma membranes of enucleate sieve elements (SEs) in tobacco, potato, and tomato. Analysis by in situ hybridization showed that SUT1 mRNA localizes mainly to the SE and is preferentially associated with plasmodesmata. Antisense inhibition of SUT1 expression under control of a companion cell (CC)-specific promoter indicated synthesis of SUT1 mRNA in the CC. These results provide evidence for targeting of plant endogenous mRNA and potentially SUT1 protein through phloem plasmodesmata and for sucrose loading at the plasma membrane of SE.

The role of FDG-PET in the preoperative assessment of N-staging in head and neck cancer

This prospective study based on 48 patients showed that FDG-PET has a significantly higher sensitivity for the detection of lymph node metastases compared with palpation and it appears that FDG-PET has a similar sensitivity to CT-scanning. According to our data, FDG-PET is a highly specific method in the evaluation of neck nodes. This new imaging technique allows a tridimensional study and is easy to interpret. Therefore, FDG-PET seems to be a valuable imaging technique for the detection of cervical lymph node metastasis.

Polymorphonuclear leukocytes play a key role in the generation of "wire-loop" lesions induced by a murine IgG3 rheumatoid factor

Murine IgG3 anti-IgG2a rheumatoid factor (RF) monoclonal antibodies (mAb) with cryoglobulin activity are able to induce skin leukocytoclastic vasculitis and glomerulonephritis resembling "wire-loop" glomerular lesions in normal mice. Since polymorphonuclear leukocyte (PMN) infiltration is one of the major pathological changes observed in both types of lesions, we determined the role of PMN and complement in the generation of these two different lesions, induced by 6-19 IgG3 RF mAb, by interfering with adhesion molecules known for their involvement of PMN-endothelial cell interaction or by depleting mice of their PMN or C3. Our results have demonstrated that first, the PMN-endothelial cell interaction mediated by leukocyte function-associated antigen 1 (LFA-1) and intercellular adhesion molecule 1 (ICAM-1) was crucial for the generation of 6-19 RF mAb-induced skin leukocytoclastic vasculitis, but not for glomerular lesions; second, PMN played an active role in the development of "wire-loop" glomerular lesions; in the absence of the PMN glomerular infiltration, 6-19 RF mAb induced a different type of glomerular lesions, characterized by voluminous intracapillary thrombi and mesangial deposits, but not subendothelial deposits; and third, the activation of the complement system did not appear to play a major role in both skin and glomerular lesions.