Études génétiques moléculaires des gènes de la polarité planaire cellulaire dans les anomalies du tube neural chez l’Homme

Les anomalies du tube neural (ATN) sont des malformations congénitales parmi les plus fréquentes chez l’humain en touchant 1-2 nouveau-nés par 1000 naissances. Elles résultent d’un défaut de fermeture du tube neural pendant l’embryogenèse. Les formes les plus courantes d'ATN chez l'homme sont l'anencéphalie et le spina-bifida. Leur étiologie est complexe impliquant à la fois des facteurs environnementaux et des facteurs génétiques. Un dérèglement dans la signalisation Wnt, incluant la signalisation canonique Wnt/β-caténine et non-canonique de la polarité planaire cellulaire (PCP), peut causer respectivement le cancer ou les anomalies du tube neural (ATN). Les deux voies semblent s’antagoniser mutuellement. Dans cette étude, nous investiguons les rôles de Lrp6 et deANKRD6, entant qu’interrupteurs moléculaires entre les deux voies de signalisation Wnt, et CELSR1, en tant que membre de la PCP, chez la souris mutante Skax26m1Jus, générée par l’agent mutagène N-Ethyl-N-Nitrosuera, et dans une cohorte de patients humains ATN. Pour Lrp6, nous avons démontré que Skax26m1Jus représente un allèle hypermorphe de Lrp6 avec une augmentation de l’activité de la signalisation Wnt/canonique et une diminution de l’activité JNK induite par la voie PCP. Nous avons également montré que Lrp6Skax26m1Jus interagit génétiquement avec un mutant PCP (Vangl2Lp) où les doubles hétérozygotes ont montré une fréquence élevée d’ATN et des défauts dans la polarité des cellules ciliées de la cochlée. Particulièrement, notre étude démontre l'association des nouvelles et rares mutations faux-sens dans LRP6 avec les ATN humaines. Nous montrons que trois mutations de LRP6 causent une activité canonique réduite et non-canonique élevée. Pour ANKRD6, nous avons identifié quatre nouvelles et rares mutations faux-sens chez 0,8% des patients ATN et deux chez 1,3% des contrôles. Notamment, seulement deux, des six mutations validées (p.Pro548Leu et p.Arg632His) ont démontré un effet significatif sur l’activité de ANKRD6 selon un mode hypomorphique. Pour CELSR1, nous avons identifié une mutation non-sens dans l'exon 1 qui supprime la majeure partie de la protéine et une délétionde 12 pb. Cette perte de nucléotides ne change pas le cadre de lecture et élimine un motif putatif de phosphorylation par la PKC " SSR ". Nous avons également détecté un total de 13 nouveaux et rares variants faux-sens qui avaient été prédits comme étant pathogènes in silico. Nos données confirment le rôle inhibiteur de Lrp6 dans la signalisation PCP pendant la neurulation et indiquent aussi que les mutations faux-sens identifiées chez LRP6 et ANKRD6 pourraient affecter un équilibre réciproque et un antagonisme très sensible à un dosage précis entre les deux voies Wnt. Ces variants peuvent aussi agir comme facteurs prédisposants aux ATN. En outre, nos résultats impliquent aussi CELSR1 comme un facteur de risque pour les anomalies du tube neural ou l’agénésie caudale. Nos résultats fournissent des preuves supplémentaires que la voie de signalisation PCP a un rôle pathogène dans ces malformations congénitales et un outil important pour mieux comprendre leurs mécanismes moléculaires.

Studies on IL-18 in HIV infection : effects of the cytokine on intestinal integrity, and platelets as a new source of the cytokine

L'interleukine IL-18 (IL-18), un membre de la famille de l’IL-1, est une cytokine pro-inflammatoire multifonctionnelle. Elle est produite par les monocytes, les macrophages, les cellules dendritiques, les cellules épithéliales, les kératinocytes et le cortex surrénal dans le corps humain. Cette cytokine est d'abord produite comme une protéine précurseure inactive, qui est par la suite clivée en une forme mature par la caspase-1 activée. La caspase, en elle-même, existe comme précurseur inactif dans les cellules humaines et requiert l'assemblage d'inflammasomes pour son activation. L'IL-18 pour joue un rôle clé dans la médiation des conditions inflammatoires. Notre laboratoire et d'autres ont montré que l'infection par le VIH est accompagnée d'une augmentation des taux circulants d'IL-18 avec une diminution des niveaux de son antagoniste, l'interleukine-18 binding protein (IL-18BP). Dans cette thèse, nous démontrons pour que l'IL-18 est également produite et sécrétée par les plaquettes humaines lors de leur activation. Les plaquettes contiennent des composants de l'inflammasome. Ils assemblent et activent la caspase-1, qui ensuite traite le précurseur de l'IL-18 dans sa forme mature au cours du processus d'activation des plaquettes. La cytokine est synthétisée de novo lors de l'activation des plaquettes. Contrairement à l'IL-18, les plaquettes expriment constitutivement l’IL-18BP, et la libèrent de manière constitutive, ainsi que lors de l'activation. L'IL-18 et l'IL-18BP sont colocalisés avec CD63, un marqueur pour les granules α des plaquettes. L'IL-18 libéré des plaquettes constitue la source principale de cette cytokine dans la circulation humaine chez les individus sains. Nous avons identifié des concentrations faibles de cette cytokine dans les lysats de plaquettes chez les individus infectés par le VIH par rapport à ceux en santé. D'autre part, les concentrations ont été augmentées dans le sérum et le plasma pauvre en plaquettes chez les individus infectés. Des résultats similaires ont été obtenus avec l'IL-18BP dans les lysats de plaquettes d'individus sains et infectés par le VIH. Cependant, des quantités plus faibles de cet antagoniste ont été trouvées dans le sérum et le plasma pauvre en plaquettes d'individus infectés par le VIH par rapport à ceux en santé. Nos résultats ont des implications importantes pour les maladies inflammatoires chroniques dans laquelle une activité accrue de l'IL-18 joue un rôle pathogène. Le VIH est également accompagné par une inflammation intestinale et une diminution de l'intégrité intestinale, mesurée par la réparation de la muqueuse, la régénération et la perméabilité. Cependant, on en sait peu sur la relation entre le niveau élevé de l'IL-18 associé à l'infection au VIH et la perméabilité intestinale: ceci n'a jamais été étudié. Dans cette thèse, nous démontrons le rôle du virus et sa protéine Tat à augmenter la production d'IL-18 chez deux lignées de cellules épithéliales intestinales (HT29 et Caco2) ainsi qu'une diminution de l'IL-18BP. L'IL-18 induit une hyperperméabilité de la barrière épithéliale en perturbant à la fois les jonctions serrées et adhérentes, et ce, en modulant l'expression et la distribution de l'occludine, de claudine-2 et de la bêta-caténine. Une désorganisation de l'actine F a également été observée dans les cellules lors de l'incubation avec l'IL-18. Les mêmes observations ont été faites avec la protéine Tat du VIH-1. Après une incubation prolongée, l'IL-18 a causé la mort des cellules intestinales et induit l'apoptose par l'activation de la caspase-1 et la caspase-3. Fait intéressant, les taux plasmatiques de lipopolysaccharides chez trois catégories différentes de patients au VIH (ART-naïf, ART-traitée et contrôleurs élite) sont en corrélation avec les niveaux plasmatiques de l'IL-18. Enfin, nous avons étudié la voie de signalisation à travers laquelle l'IL-18 induit une perméabilité intestinale accrue. En bref, nos études identifient les plaquettes comme une source importante d'IL-18, et leur activation lors d'une infection à VIH contribue à des concentrations accrues de cette cytokine. Le virus entraine également l'augmentation de la production de cytokines par les cellules épithéliales intestinales. L'activité biologique accrue de ces cytokines contribue à la pathogenèse du sida en augmentant la perméabilité intestinale et en causant la mort des cellules intestinales. L'IL-18 pourrait servir de cible moléculaire pour retarder la progression du sida et réduire l'inflammation chronique dans un stade précoce d'une infection à VIH.

Peritoneal Dialysis-Related Peritonitis Due to Staphylococcus aureus: A Single-Center Experience over 15 Years

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Pre- and post-transplant anti-myosin and anti-heat shock protein antibodies and cardiac transplant outcome

Background: the purpose this study was to investigate the relationship of anti-myosin and anti-heat shock protein immunoglobulin G (IgG) serum antibodies to the original heart disease of cardiac transplant recipients, and also to rejection and patient survival after cardiac transplantation.Methods: Anti-myosin and anti-heat shock protein (anti-hsp) IgG antibodies were evaluated in pre-transplant sera from 41 adult cardiac allograft recipients and in sequential post-transplant serum samples from 11 recipients, collected at the time of routine endomyocardial biopsies during the first 6 months after transplantation. In addition, the levels of these antibodies were determined from the sera of 28 healthy blood donors.Results: Higher anti-myosin antibody levels were observed in pre-transplant sera than in sera from normal controls. Moreover, patients with chronic Chagas heart disease showed higher anti-myosin levels than patients with ischemic heart disease, and also higher levels, although not statistically significant, than patients with dilated cardiomyopathy. Higher anti-hsp levels were also observed in patients compared with healthy controls, but no significant differences were detected among,the different types of heart diseases. Higher pre-transplant anti-myosin, but not anti-hsp, levels were associated with lower 2-year post-transplant survival. In the post-transplant period, higher anti-myosin IgG levels were detected in sera collected during acute rejection than in sera collected during the rejection-free period, whereas anti-hsp IgG levels showed no difference between these periods.Conclusions: the present findings are of interest for post-transplant management and, in addition, suggest a pathogenic role for anti-myosin antibodies in cardiac transplant rejection, as has been proposed in experimental models of cardiac transplantation.

Phenotypical characterization of Candida spp. isolated from crop of parrots (Amazona spp.)

Renata G. Vieira R.G. & Acqua Coutinho S.D. 2009. Phenotypical characterization of Candida spp. isolated from crop of parrots (Amazona spp.). Pesquisa Veterinaria Brasileira 29(6):452-456. Curso de Pos-Graduagdo em Imunopatologia Veterinaria, Universidade Paulista, Rua Agariba 48, São Paulo, SP 05053010, Brazil. E-mail: selene@uol.com.brThe purpose of this study was to characterize Candida isolates from crop of parrots. Forty baby parrots of genus Amazona, species aestiva and amazonica that were apprehended from wild animal traffic were used: 18 presented ingluvitis and 22 other alterations, but showing general debilitation. Samples were seeded on Sabouraud dextrose agar with chloramphenicol after be obtained by the introduction of urethral probe through the esophagus. Based on morphology and biochemical reactions (API 20C) Candida was confirmed; it was still searched the production of proteinase and phospholipase, virulence factors for Candida species. Candida spp. were isolated from 57.5% parrots, being 72.2% from birds with ingluvitis and 45.5% from without ones. Twenty-five strains of Candida were isolated, 60% and 40%, respectively from parrots with and without ingluvitis, and were speciated: 28% C. humicola, 24% C. parapsilosis, 20% C. guilliermondii, 20% C. famata, and 8% C. albicans. These results demonstrate that C. albicans is not the most frequent species isolated, and it is the first report that shows C. guilliermondii, C. famata, and C. humicola causing infection in parrots. Many isolates presented filamentation (76%), 100% produced proteinase and 68% phospholipase. The observation of Candida spp. producing virulence factors reinforce the pathogenic role of these yeasts in the cases studied.

A cross-sectional electromyography assessment in linear scleroderma patients

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Parâmetros ecocardiográficos e variabilidade da frequência cardíaca em fêmeas caninas com sepse de ocorrência natural devido à piometra e suas correlações com valores séricos de TNF-alfa, IL-1 beta, IL-6, IL-10 e proteína C reativa

Pós-graduação em Medicina Veterinária - FCAV

Fluctuation of Anti-Endothelial Cell Antibody Titers in Mixed Connective Tissue Disease

Background: Antibodies directed against endothelial cell surface antigens have been described in many disorders and have been associated with disease activity. Since the most prominent histopathologic feature in mixed connective tissue disease (MCTD) is the widespread and unique proliferative vascular lesion, our aim was to evaluate the frequency of anti-endothelial cell antibodies (AECA) in this condition. Objectives: To evaluate the frequency of AECA in this disease and assess its clinical and laboratory associations. Methods: Seventy-three sera from 35 patients with MCTD (Kasukawa's criteria), collected during a 7 year period, were tested for immunoglobulins G and M (IgG and IgM) AECA by cellular ELISA, using HUVEC (human umbilical vein endothelial cells). Sera from 37 patients with systemic lupus erythematosus (SLE), 22 with systemic sclerosis (SSc) and 36 sera from normal healthy individuals were used as controls. A cellular ELISA using HeLa cells was also performed as a laboratory control method. Results: IgG-AECA was detected in 77% of MCTD patients, 54% of SLE patients, 36% of SSc patients and 6% of normal controls. In MCTD, IgG-AECA was associated with vasculitic manifestations, disease activity and lymphopenia, and was also a predictor of constant disease activity. Immunosuppressive drugs were shown to reduce IgG-AECA titers. Since antibodies directed to HeLa cell surface were negative, AECA was apparently unrelated to common epitopes present on epithelial cell lines. Conclusions: AECA are present in a large proportion of patients with MCTD and these antibodies decrease after immunosuppressive treatment. IMAJ 2012; 14:84-87

Increased Expression of Regulatory T Cells and Down-Regulatory Molecules in Lepromatous Leprosy

T regulatory cells (Tregs) play an important role in the mechanism of host's failure to control pathogen dissemination in severe forms of different chronic granulomatous diseases, but their role in leprosy has not yet been elucidated; 28 newly diagnosed patients (16 patients with lepromatous leprosy and 12 patients with tuberculoid leprosy) and 6 healthy Mycobacterium leprae-exposed individuals (contacts) were studied. Tregs were quantified by flow cytometry (CD4+ CD25+ Foxp3+) in peripheral blood mononuclear cells stimulated in vitro with a M. leprae antigenic preparation and phytohemagglutinin as well as in skin lesions by immunohistochemistry. The lymphoproliferative (LPR), interleukin-10 (IL-10), and interferon-gamma (IFN-gamma) responses of the in vitro-stimulated peripheral blood mononuclear cells and the in situ expression of IL-10, transforming growth factor-beta (TGF-beta), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) were also determined. We show that M. leprae antigens induced significantly lower LPR but significantly higher Treg numbers in lepromatous than tuberculoid patients and contacts. Mitogen-induced LPR and Treg frequencies were not significantly different among the three groups. Tregs were also more frequent in situ in lepromatous patients, and this finding was paralleled by increased expression of the antiinflammatory molecules IL-10 and CTLA-4 but not TGF-beta. In lepromatous patients, Tregs were intermingled with vacuolized hystiocyte infiltrates all over the lesion, whereas in tuberculoid patients, Tregs were rare. Our results suggest that Tregs are present in increased numbers, and they may have a pathogenic role in leprosy patients harboring uncontrolled bacillary multiplication but not in those individuals capable of limiting M. leprae growth.

NF-κB activation mediates crystal translocation and interstitial inflammation in adenine overload nephropathy

Adenine overload promotes intratubular crystal precipitation and interstitial nephritis. We showed recently that these abnormalities are strongly attenuated in mice knockout for Toll-like receptors-2, -4, MyD88, ASC, or caspase-1. We now investigated whether NF-κB activation also plays a pathogenic role in this model. Adult male Munich-Wistar rats were distributed among three groups: C (n = 17), receiving standard chow; ADE (n = 17), given adenine in the chow at 0.7% for 1 wk and 0.5% for 2 wk; and ADE + pyrrolidine dithiocarbamate (PDTC; n = 14), receiving adenine as above and the NF-κB inhibitor PDTC (120 mg•kg-1•day-1 in the drinking water). After 3 wk, widespread crystal deposition was seen in tubular lumina and in the renal interstitium, along with granuloma formation, collagen accumulation, intense tubulointerstitial proliferation, and increased interstitial expression of inflammatory mediators. Part of the crystals were segregated from tubular lumina by a newly formed cell layer and, at more advanced stages, appeared to be extruded to the interstitium. p65 nuclear translocation and IKK-α increased abundance indicated activation of the NF-κB system. PDTC treatment prevented p65 migration and normalized IKK-α, limited crystal shift to the interstitium, and strongly attenuated interstitial fibrosis/inflammation. These findings indicate that the complex inflammatory phenomena associated with this model depend, at least in part, on NF-κB activation, and suggest that the NF-κB system may become a therapeutic target in the treatment of chronic kidney disease.

Distinct eosinophil cytokine expression patterns in skin diseases - the possible existence of functionally different eosinophil subpopulations

The function of eosinophils has been attributed to host defense, immunomodulation, and fibrosis. Although eosinophils are found among infiltrating cells in a broad spectrum of skin diseases, their pathogenic role remains uncertain. This study aimed to analyze the cytokine expression by eosinophils in different skin diseases.

Intralesional bovine papillomavirus DNA loads reflect severity of equine sarcoid disease

REASONS FOR PERFORMING STUDY: Sarcoids are nonmetastasising, yet locally aggressive skin tumours that constitute the most frequent neoplasm in equids. Infection by bovine papillomaviruses types 1 and 2 (BPV-1, BPV-2) has been recognised as major causative factor in sarcoid pathogenesis, but a possible correlation of intralesional virus load with disease severity has not been established thus far. HYPOTHESIS: Given the pathogenic role of BPV-1 and BPV-2 in sarcoid disease, we suggest that intralesional viral DNA concentration may reflect the degree of affection. METHODS: Severity of disease was addressed by recording the tumour growth kinetics, lesion number and tumour type for 37 sarcoid-bearing horses and one donkey. Viral load was estimated via quantitative real-time PCR (qPCR) of the E2, E5, L1 and L2 genes from the BPV-1/-2 genome for one randomly selected lesion per horse and correlated with disease severity. RESULTS: Quantitative PCR against E2 identified viral DNA concentrations ranging from 0-556 copies/tumour cell. Of 16 horses affected by quiescent, slowly growing single tumours or multiple mild-type lesions, 15 showed a viral load up to 1.4 copies per cell. In stark contrast, all equids (22/22) bearing rapidly growing and/or multiple aggressive sarcoids had a viral load between 3 and 569 copies per cell. Consistent results were obtained with qPCR against E5, L1 and L2. CONCLUSIONS: While tumours of the same clinical type carried variable virus load, confirming that viral titre does not determine clinical appearance, we identified a highly significant correlation between intralesional viral load and disease severity. POTENTIAL RELEVANCE: The rapid determination of BPV viral load will give a reliable marker for disease severity and may also be considered when establishing a therapeutic strategy.

[Diagnostics of autoimmune diseases]

Autoantibodies play a key role in diagnostic laboratories as markers of autoimmune diseases. In addition to their role as markers they mediate diverse effects in vivo. Autoantibodies with protective effect have been described. Natural protective IgM autoantibodies against tumour-antigens of malignant cells or their precursors may contribute to increased survival rates of carcinoma patients. In a mouse model of systemic lupus erythematosus it has been shown that anti-dsDNA IgM autoantibodies protect from glomerular damage. In contrast, a direct pathogenic role of autoantibodies has been well established e.g. in myasthenia gravis or in Goodpasture syndrome. Similarly autoantibodies against SSA Ro52 are detrimental in neonatal lupus erythematosus with congenital heart block. Moreover, putatively protective autoantibodies may become pathogenic during the course of the disease such as the onconeuronal autoantibodies whose pathogenicity depends on their compartmentalisation. In patients with paraneoplastic syndromes tumour cells express proteins that are also naturally present in the brain. Anti-tumour autoantibodies which temporarily suppress tumour growth can provoke an autoimmune attack on neurons once having crossed the blood-brain barrier and cause specific neurological symptoms. Only a restricted number of autoantibodies are useful follow-up markers for the effectiveness of treatment in autoimmune diseases. Certain autoantibodies hold prognostic value and appear years or even decades before the diagnosis of disease such as the antimitochondrial antibodies in primary biliary cirrhosis or anti-citrullinated protein (CCP)-antibodies in rheumatoid arthritis. It is crucial to know whether the autoantibodies in question recognise linear or conformational epitopes in order to choose the appropriate detection methods. Indirect immunofluorescence microscopy remains a very useful tool for confirmation of results of commercially available immunoassays and for detection of special and rare autoantibodies that otherwise often remain undetected. Standardisation of autoimmune diagnostics is still underway and requires joint efforts by laboratories, clinicians and industry.

Alternative splicing of pre-mRNA in cancer: focus on G protein-coupled peptide hormone receptors

Through alternative splicing, multiple different transcripts can be generated from a single gene. Alternative splicing represents an important molecular mechanism of gene regulation in physiological processes such as developmental programming as well as in disease. In cancer, splicing is significantly altered. Tumors express a different collection of alternative spliceoforms than normal tissues. Many tumor-associated splice variants arise from genes with an established role in carcinogenesis or tumor progression, and their functions can be oncogenic. This raises the possibility that products of alternative splicing play a pathogenic role in cancer. Moreover, cancer-associated spliceoforms represent potential diagnostic biomarkers and therapeutic targets. G protein-coupled peptide hormone receptors provide a good illustration of alternative splicing in cancer. The wild-type forms of these receptors have long been known to be expressed in cancer and to modulate tumor cell functions. They are also recognized as attractive clinical targets. Recently, splice variants of these receptors have been increasingly identified in various types of cancer. In particular, alternative cholecystokinin type 2, secretin, and growth hormone-releasing hormone receptor spliceoforms are expressed in tumors. Peptide hormone receptor splice variants can fundamentally differ from their wild-type receptor counterparts in pharmacological and functional characteristics, in their distribution in normal and malignant tissues, and in their potential use for clinical applications.

Increased expression of IL-12p70 and IL-23 by multiple dendritic cell and macrophage subsets in plaque psoriasis

BACKGROUND: Psoriasis is a chronic immune-mediated skin disease, in which interleukins 12 and 23 have been postulated to play a critical role. However, the cellular source of these cytokines in psoriatic lesions are still poorly defined and their relative contribution in inducing skin inflammation has been discussed controversially. OBJECTIVES: To investigate immunoreactivity of the bioactive forms of IL-12 and IL-23 in plaque psoriasis and to characterize the dendritic cell (DC) and macrophage subsets responsible for the production of these cytokines. METHODS: Immunohistochemistry was performed on normal skin (n=11) as well as non-lesional (n=11) and lesional (n=11) skin of patients with plaque psoriasis using monoclonal antibodies targeting the bioactive forms of IL-12 (IL-12p70) and IL-23 (IL-23p19/p40) on serial cryostat sections using the alkaline phosphatase-antialkaline phosphatase. Co-localization of IL-12 and IL-23 with different dendritic cells and macrophage cell markers (CD1a, CD11c, CD14, CD32, CD68, CD163, CD208/DC-LAMP) was performed using double immunofluorescence staining. RESULTS: Immunoreactivity for IL-12 and IL-23 was significantly enhanced in lesional psoriatic skin as compared to non-lesional and normal skin. No difference was observed between IL-12 and IL-23 immunoreactivity in any skin types. Both IL-12 and IL-23 immunoreactivity was readily detected mainly in CD11c+, CD14+, CD32+, CD68+ and some CD163+, DC-LAMP+ cells. IL-12 and occasionally IL-23 were also found in some CD1a+ dendritic cells. In addition, an enhanced expression mainly of IL-23 was observed in keratinocytes. CONCLUSIONS: Bioactive forms of IL-12 and IL-23 are highly expressed in various DC and macrophage subsets and their marked in situ production suggest that both cytokines have crucial pathogenic role in psoriasis.