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Biomedical subjects

P Youinou

Publications and source records attributed to P Youinou.

At least 19 recordsLinked to original sources
PubMed2002

CD5-induced apoptosis of B cells in some patients with chronic lymphocytic leukemia.

Although B chronic lymphocytic leukemia (B-CLL) is characterized by prolonged survival of CD5(+) B cells in vivo, these cells apoptose spontaneously in vitro. The effect of CD5 ligation on apoptosis was studied in 27 newly diagnosed patients with B-CLL, in relation to the expression of surface IgM (sIgM), CD79b, CD38, CD72 and CD19. B cells from 15 patients (group I) were resistant to anti-CD5-induced apoptosis, whereas apoptosis above spontaneous levels was seen in the remaining 12 studied (group II). Group II was then subdivided on the basis of differences in the time required to reach maximum apoptosis: whilst B cells from seven patients underwent apoptosis by 18 h, those from the remaining five needed 36 h to apoptose. The expression of sIgM, CD5, CD79b and CD38 was higher in group II than group I, suggesting that signaling for apoptosis might operate via CD79, and that CD38 expression was required. As shown by flow cytometry and confirmed by Western blotting, apoptosis was associated with a decrease in the ratios of Bcl-2/Bax and Bcl(XL)/Bax, due to an increase in the level of Bax, but no change in that of Bcl-2. This heterogeneous apoptotic response to CD5 ligation offers an explanation for the incomplete success of anti-CD5 monoclonal therapy, and might help identify patients who would respond to such treatment.

Adolescent↗
PubMed2002

Consequences of Fc gamma receptor type III reactivity in non-organ-specific autoimmune diseases.

Polymorphonuclear neutrophils (PMNs) express constitutively the Fc gamma receptors (Fc gamma Rs) Fc gamma RIIIb and Fc gamma RIIa for the Fc part of IgG, and soluble Fc gamma RIIIb (sFc gamma RIIIb) has been identified. Elevated levels of sFc gamma RIIIb were detected in non-organ-specific autoimmune conditions, and there was a considerably decreased number of PMNs undergoing apoptosis in the presence of sFc gamma RIIIb. Anti-Fc gamma RIIIb autoantibodies (autoAbs) have also been described in such patients. They are not cytotoxic to these cells, but they extend their survival. The anti-apoptotic signal can be transduced through Fc gamma RIIa and/or CD11b, the beta-chain of the complement receptor 3. However, Fc gamma RIIIb appears to be also competent. Anti-Fc gamma RIIIb-conditioned supernatant from cultured PMNs induces the transcription of messenger RNA for granulocyte colony-stimulating factor and granulocyte/macrophage colony-stimulating factor, followed by protein synthesis. The delay in apoptosis may be generated by a downregulation of the death promoter Bax. Inflammation might thus be modulated by sFc gamma RIIIb and anti-Fc gamma RIIIb autoAbs in systemic diseases.

Antigens, CD↗
PubMed2002

The role of anti-endothelial cell antibodies in Kawasaki disease - in vitro and in vivo studies.

Kawasaki disease (KD) is a systemic vasculitis with cardiac and noncardiac complications. Anti--endothelial cell antibodies (AECA) are found among many patients with KD. The aim of this study was to investigate the pathogenic role of AECA in KD using in vitro and in vivo experimental models. F(ab)2 fragments of IgG-AECA and IgM-AECA were affinity purified from a patient with active KD. Their endothelial binding and ability to induce a pro-adhesive and a pro-inflammatory phenotype were evaluated in vitro. Twenty Balb/C mice were immunized with KD-AECA or with control Ig (N-Ig) to induce AECA in a murine model by the idiotypic manipulation method. Both KD-AECA isotypes bind significantly to human umbilical vein endothelial cell (HUVEC) compared to N-Ig. The in vitro activity was demonstrated by the antibodies ability to activate endothelial cells resulting in increased IL-6 secretion, adhesion molecule expression and monocytic cell line (U937) adherence to HUVEC. Five of the mice that received KD-AECA developed murine AECA after 3 months. None of the mice that received N-Ig produced AECA. The murine AECA increased monocyte adhesion to EC in vitro, similarly to the AECA used for immunization. Furthermore, all the mice that developed AECA had proteinuria and IgG deposition in the renal mesangium. No histological or immunofluorescence evidence of cardiac vasculitis could be detected. AECA might play a role in the emergence of some of KD manifestations.

Animals↗
PubMed2002

Distinguishing features of anti-beta2 glycoprotein I antibodies between patients with leprosy and the antiphospholipid syndrome.

Anticardiolipin (ACA), anti-beta2 glycoprotein I (beta2GPI), and antiprothrombin antibodies of IgG and IgM classes were quantitated by enzyme-linked immunosorbent assays in 176 untreated leprosy patients across the histopathological spectrum. Positivity rates ranged from 21% (IgG ACA) to 30% (IgM anti-prothrombin) versus 4% in healthy controls (p <10(-2) to 10(-3)). Levels of IgM anti-beta2GPI and IgG ACA were significantly higher in lepromatous leprosy and multibacillary patient subgroups. IgG3 was the most common subclass reactive to both beta2GPI and prothrombin in selected high-titer leprosy sera, unlike antibodies from patients with the antiphospholipid syndrome (APS) largely restricted to IgG2. In leprosy patients, but not in the APS control group, there was no statistical correlation between ACA and anti-beta2GPI antibody levels. Likewise, a large fraction of anti-beta2GPI positive sera (36/45 and 28/44 for IgG and IgM, respectively) were unreactive in the standard ACA assay. Most assayed anti-beta2GPI antibodies from leprosy patients showed (i) ability to recognize both human and bovine beta2GPI immobilized on non-irradiated polystyrene plates, (ii) concentration-dependent inhibition of binding by cardiolipin, and (iii) relatively high avidity binding to fluid-phase beta2GPI, thereby differing from those found in APS. Finally, the location of the major epitopic region on the beta2GPI molecule targeted by autoantibodies was different in leprosy and APS, as assessed by direct binding to domain I- and V-deleted mutants and competition with the mouse monoclonal antibody 8C3, directed at domain I. Thus, leprosy-related antiphospholipid antibodies comprise persistent IgG and IgM anti-beta2GPI that differ from APS-related ones with respect to IgG subclass, avidity and epitope specificity, possibly reflecting distinct pathophysiological significance.

Adolescent↗
PubMed2001

Cross-linking of human FcgammaRIIIb induces the production of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor by polymorphonuclear neutrophils.

We have reported that human autoantibodies reacting with the polymorphonuclear neutrophil (PMN)-anchored FcgammaRIIIb (CD16) protect these cells from spontaneous apoptosis. In this study, we used anti-CD16 F(ab')(2) to delineate the mechanism(s) whereby the PMN life span is extended. As documented using four methods, CD16 cross-linking impeded spontaneous apoptosis, whereas anti-CD18 F(ab')(2) exerted no effect. Incubation of PMNs with anti-CD16 prevented the up-regulation of beta(2) integrins, particularly CD11b, which is the alpha-chain of complement receptor type 3, but also CD18, which is its beta-chain, as well as CD11a and CD11c. Anti-CD16-conditioned supernatant of PMNs diminished the percentage of annexin V-binding fresh PMNs after another 18 h in culture, whereas the negative control anti-CD18 had no effect. The expression of mRNA for G-CSF and GM-CSF was induced by anti-CD16, followed by the release of G-CSF and GM-CSF in a dose-dependent manner. Anti-G-CSF and anti-GM-CSF mAbs abrogated the antiapoptotic effect of the related growth factors. The delay in apoptosis was accompanied by a down-regulated expression of Bax, and a partial reduction of caspase-3 activity. These data suggest an autocrine involvement of anti-CD16-induced survival factors in the rescue of PMNs from spontaneous apoptosis. Thus, apoptosis of aged PMNs can be modulated by signaling through FcgammaRIIIb, which may occur in patients with PMN-binding anti-FcgammaRIIIb autoantibodies.

Antibodies, Monoclonal↗
PubMed2001

[Immunopathology of Gougerot-Sjogren syndrome].

Sjögren's syndrome presents as an autoimmune exocrinopathy, and the term autoimmune epitheliitis has recently been coined. The major lesion is a lymphocyte infiltrate affecting the salivary glands and consisting predominantly of activated CD4+ T cells. The remaining 20% B lymphocytes, first polyclonal, turn out to be monoclonal. Epithelial cells are endowed with a key-part in the play, inasmuch as they gather together most of the Sjögren's syndrome-specific target autoantigens within apoptotic bodies, and possess all the characteristics of antigen presenting cells. There appears to be every likelihood that the sequence is triggered off by a thus far unknown virus.

Apoptosis↗
PubMed2001

Soluble Fcgamma receptor IIIb alters the function of polymorphonuclear neutrophils but extends their survival.

We have established that polymorphonuclear neutrophil (PMN)-binding anti-Fcgamma receptor IIIb (FcgammaRIIIb) autoantibodies (autoAb) inhibit the function of these cells but extend their survival. Here, we show that recombinant FcgammaRIIIb (rFcgammaRIIIb), as well as purified FcgammaRIIIb (pFcgammaRIIIb), deteriorated the PMN adherence and respiratory burst in a dose-dependent manner. Furthermore, rFcgammaRIIIb and pFcgammaRIIIb reduced the level of annexin V-binding PMN from 23.6 +/- 1.6 % to 6.3 +/- 1.0 and 11.0 +/- 1.0 %, respectively, while human serum albumin exerted no effects. Incubation of rFcgammaRIIIb with those autoAb binding to soluble FcgammaRIIIb resulted in the attachment of such immune complexes (IC) to the cells, thereby also delaying apoptosis (44.9 +/- 5.9 versus 18.0 +/- 2.0 % annexin V-binding PMN after 16 hours). Soluble FcgammaRIIIb, in concert with FcgammaRIIIb / anti-FcgammaRIIIb IC, produced similar effects in that the percentage of annexin V-binding PMN declined to 16.0 +/-1.9 %. It was thus suggested that FcgammaRIIIb / anti-FcgammaRIIIb IC inserted the Fc region of their IgG into the membrane FcgammaRIIIb. Such an interpretation is consistent with our finding that, whereas aggregated IgG and anti-FcgammaRIIIb monoclonal Ab prevented membrane FcgammaRIIIb / IC interaction, neither soluble FcgammaRIIIb, nor anti-cgammaRII did so. We conclude that the function and the life span of PMN are influenced synergistically by soluble FcgammaRIIIb and anti-FcgammaRIIIb autoAb.

Antigen-Antibody Complex↗
PubMed2001

Ability of the American College of Rheumatology 1987 criteria to predict rheumatoid arthritis in patients with early arthritis and classification of these patients two years later.

OBJECTIVE: To determine how well the American College of Rheumatology (ACR; formerly, the American Rheumatism Association) 1987 classification criteria for rheumatoid arthritis (RA), when used at study inclusion in a cohort of 270 patients with early (<1 year) arthritis, predicted a diagnosis of RA 2 years later and how well they classified these patients at the end of the 2 years. METHODS: Patients were evaluated during 1995-1997 at 7 hospitals in the Brittany region of France. Patients were evaluated at 6-month intervals until November 1999. The diagnosis made by a panel of 5 rheumatologists (P5R) after the last visit was used as the "gold standard." The ACR 1987 criteria for RA were applied prospectively, without taking into account the initial diagnosis. RESULTS: At the last visit (mean +/- SD followup 29.1 +/- 11.8 months; median 30 months), the P5R diagnosed RA in 98 patients. At the last visit, classification by the ACR criteria was satisfactory, and the combination of an office-based rheumatologist's (OBR's) diagnosis of RA and fulfillment of the ACR criteria was sensitive (87%; 85 of 98 RA patients had both) and highly specific (99%; 170 of 172 non-RA patients did not have both). Application of the criteria at the first visit was of limited value for predicting a diagnosis of RA 2 years later. CONCLUSION: After a 2-year followup, the ACR 1987 classification criteria used in combination with an OBR's diagnosis were effective in distinguishing patients with and without RA. The criteria were not useful for predicting RA in patients with arthritis onset within the previous year. Some patients who met the criteria at baseline and after 2 years did not have RA, suggesting that incorporating exclusion criteria may improve the performance of the ACR criteria when used without taking into account the diagnosis by a rheumatologist, particularly in early arthritis.

Adolescent↗
PubMed2001

Functional heterogeneity of anti-endothelial cell antibodies.

While it has been claimed that some anti-endothelial cell antibodies (AECA) activate EC, there is also evidence that others trigger apoptosis. To address the issue of whether activation is a prerequisite for AECA-mediated apoptosis of EC, 23 AECA-positive sera were evaluated for their ability to induce activation and/or apoptosis. Activation was defined as an over-expression of E-selectin and intercellular adhesion molecule 1. Optical microscopy, annexin V binding, hypoploid cell enumeration, and determination of poly (ADP-ribose) polymerase cleavage-related products were used to assess apoptosis. Four functional profiles were defined: 10 sera promoted activation and apoptosis (act+/apo+), one was act+/apo-, six act-/apo+, and the remaining six act-/apo-. The reduced membrane expression of thrombomodulin was associated with apoptosis, rather than activation. Caspase-3 was implicated in the two models of apoptosis, the ratios of several survival proteins to Bax decreased, regardless of the ability of apo+ AECA to activate the cells, while radical oxygen species did not appear to be involved. Furthermore, it occurred that macrophages engulfed EC treated with apoptosis-promoting AECA, but not those incubated with AECA that did not induce apoptosis. Hence, AECA represent an extremely heterogeneous family of autoantibodies, not only because of the variety of their target antigens, but also the subsequent diversity of their effects.

Antibody Diversity↗
PubMed2001

Oxidation of beta2-glycoprotein I (beta2GPI) by the hydroxyl radical alters phospholipid binding and modulates recognition by anti-beta2GPI autoantibodies.

We investigated whether beta2-glycoprotein I (beta2GPI), the key antigen in the antiphospholipid syndrome, is susceptible to oxidative modifications by the hydroxyl radical (*OH) that may influence its lipid-binding and antigenic properties. The effects on human and bovine beta2GPI of *OH free radicals generated by gamma-radiolysis of water with 137Cs were studied. Radiolytic *OH caused a dose-dependent loss of tryptophan, production of dityrosine and carbonyl groups. dimerization and/or extensive aggregation of beta2GPI. It ensued a reduction in affinity binding to cardiolipin liposomes and loss of beta2GPI-dependent autoantibody binding to immobilized cardiolipin. Patient anti-beta2GPI antibodies (n = 20) segregated into two groups based on the effect in the beta2GPI-ELISA of beta2GPI pretreatment with *OH: enhancement (group A, n = 10) or suppression (group B, n = 10) of IgG binding. The avidities of group A antibodies for fluid-phase beta2GPI were low but increased in a dose-dependent manner upon beta2GPI irradiation, in relation to protein crosslinking. Distinguishing features of group B antibodies included higher avidities for fluid-phase beta2GPI that was no longer recognized after *OH treatment, and negative anticardiolipin tests suggesting epitope location near the phospholipid binding site. The *OH scavengers thiourea and mannitol efficiently protected against all above changes. Therefore, oxidative modifications of beta2GPI via *OH attack of susceptible amino acids alter phospholipid binding, and modulate recognition by autoantibodies depending on their epitope specificities. These findings may be of clinical relevance for the generation and/or reactivity of anti-beta2GPI antibodies.

Animals↗
PubMed2001

Anti-endothelial cell antibodies (AECA) in systemic sclerosis--increased sensitivity using different endothelial cell substrates and association with other autoantibodies.

OBJECTIVE: One of the main features of systemic sclerosis (SSc) is vascular damage, the mechanism of which is not understood. In the present study we examined whether screening of SSc patients for different anti-endothelial cells antibodies (AECA) of various origins increase the sensitivity of AECA detection in SSc patients. Secondary aim was an attempt to correlate AECA with other common autoantibodies. MATERIALS & METHODS: 478 SSc patients were studied for the presence AECA, anti-cardiolipin (aCL), anti-dsDNA, anti-heparin (AHA), anti-pyruvate dehydrogenase (PDH) and anti-PDC-E2 autoantibodies. AECA levels were detemined using human umbilical vein EC (HUVEC), bone marrow EC (BMEC), EC hybridoma (EA.hy 926) and Kaposi sarcoma EC (KS). RESULTS: Positive AECA were found in 49.5% of SSc patients (27.1% HUVEC; 34.3% BMEC; 26.3% EaHy 926 and 22.7% KS). The highest percent reactivity of AECA was obtained using microvascular BMEC. When combining BMEC and either other cell lines the reactivity ranged from 41.4% to 46%. A significant association between AECA on the one hand and AHA (p<0.001)) and anti-PDH (p<0.05) on the other was secn. Cross-reactivity with anti-PDC-E2 was excluded by inhibition tests, but AHA and anti-PDH may be part of the spectrum of AECA. CONCLUSIONS: Since false-negative AECA may result from lack of expression of various antigens on a specific EC, analysis of AECA in SSc patients requires using several EC types, including microvascular EC.

Antibodies, Anticardiolipin↗
PubMed2001

Expression of B cell receptor-associated signaling molecules in human lupus.

B cell receptor (BcR) signaling requires a tight regulation of several protein tyrosine kinases and phosphatases, and associated co-receptors. Mounting evidence indicates that abnormal BcR signaling, such as occurs in SHP-1 and Lyn-deficient mice, results in production of pathogenic autoantibodies and lupus-like glomerulonephritis, suggesting that altered signaling thresholds could underlie the development of systemic autoimmunity. To test this hypothesis, we investigated expression of BcR-associated signaling molecules in lymphocytes from patients with systemic lupus erythematosus (SLE) during inactive phases of the disease. We found that the transmembrane regulatory protein tyrosine phosphatase CD45 is expressed at abnormal levels. Strikingly, this reduction persisted during four months of follow-up. By contrast, despite its potent role as a regulator of thymus-independent immune responses and of B cell life span, the CD22 co-receptor is expressed at normal levels in B lymphocytes isolated ex vivo from SLE patients. We also noted unusual levels of the cytosolic protein tyrosine kinase Lyn and the protein tyrosine phosphatase SHP-1 in the lymphocytes of the patients. Since in normal B cells Lyn and SHP-1 act in concert within a common negative pathway in which CD45 counteracts SHP-I regulatory role, we propose that this feedback regulatory pathway is crippled to different degrees in human SLE B cells. Break of the balance between positive and negative signaling molecules likely modifies the BcR signaling thresholds. Such alterations, together with other factors, may contribute to the disruption of self-tolerance in this disease.

Animals↗
PubMed2001

Differential effects of anti-Fc gamma RIIIb autoantibodies on polymorphonuclear neutrophil apoptosis and function.

Anti-Fc gamma receptor IIIb (Fc gammaRIIIb) human autoantibodies (Ab) have been classified previously into three groups, based on the results of an indirect immunofluorescence (IIF) test and an enzyme-linked immunosorbent assay (ELISA): IIF+/ELISA+ (group A), IIF+/ELISA- (group B), and IIF-/ELISA+ (group C) sera. In this study, differential effects between IIF+ autoAb, recognizing cell-bound Fc gammaR, and those ELISA+, recognizing only cell-free Fc gammaR, were studied on polymorphonuclear neutrophils (PMN). Neither group A nor B autoAb was cytotoxic, although both prolonged the survival of PMN by delaying spontaneous apoptosis. By the same extent, the PMN-binding antisera stimulated the appearance of a CD11b(dim) population, following a 12-h incubation. This event was associated with a lowered expression of beta2 integrin molecules, resulting in altered PMN function. Treatment with groups A and B autoAb reduced adhesiveness and respiratory burst. This impairment of the responses was more pronounced when the cells originated from donors NA1+ NA1+ rather than donors NA2+ NA2+. From our observations, the influences of anti-Fc gammaRIIIb autoAb on PMN survival, as well as function and subsequent dysregulation of the inflammatory response, have proven somewhat dependent on their target antigens, as determined by IIF coupled with ELISA and Fc gammaRIIIb polymorphism.

Antibody-Dependent Cell Cytotoxicity↗
PubMed2001

Ability of hand radiographs to predict a further diagnosis of rheumatoid arthritis in patients with early arthritis.

OBJECTIVE: To evaluate the ability of hand radiographs collected at study inclusion to predict a diagnosis of rheumatoid arthritis (RA) 2 years later, in a cohort of patients with early arthritis. METHODS: We evaluated 270 patients with arthritis of less than one year duration. At the first visit, all patients underwent a standardized evaluation including laboratory tests and radiographs. Followup was 30+/-11.3 mo. The hand radiographs were read by observers blinded to patient data who looked for item 7 of the 1987 ACR criteria for RA and used Sharp's method to score erosions and joint space narrowing. RESULTS: The kappa coefficient for ACR item 7 was < 0.65 for bony decalcification and > 0.8 for erosions. Intra and interobserver correlation coefficients for Sharp score ranged from 0.90 to 0.95. The "erosion" component of ACR item 7 was more specific than the full item 7 (96% versus 87.5%; p = 0.02). Sharp erosion score was not better than the erosion component of item 7 (sensitivity 17%; specificity 96%). CONCLUSION: Regardless of the criterion used, hand radiographs were of limited value to predict which patients would be considered as having RA 2 years later. Diagnostic performance was similar for the "erosions" component of the 1987 ACR item 7 and for Sharp erosion score. The full 1987 ACR item 7 (erosions or bony decalcification) performed less well.

Arthritis, Rheumatoid↗
PubMed2001

[Anti-endothelial cell antibodies in chronic leg ulcer: prevalence and significance].

BACKGROUND: Anti-endothelial cell antibodies are detected in auto-immune vasculitis and connective tissue diseases such as scleroderma, with possible pathogenic involvement. We looked for these antibodies in patients presenting chronic ulcers. PATIENTS AND METHODS: Eighty patients were tested: 35 presented vascular ulcers (27 of venous origin and 8 arterial). A control group of 14 patients with connective tissue disease and vasculitis was formed, and a third group included 31 patients without vascular or immune disease. Their sera were tested by ELISA technique on EAhy 926 cell (obtained from hybridization of human endothelial and line A 549/8 cells). RESULTS: Blood tests were positive in 37.5 p. 100 of patients. Antibodies were present in 48.5 p. 100 of patients with leg ulcers (of which 59 p. 100 (16/27) venous ulcers). Fifty-seven per cent of the autoimmune group and 12 p. 100 of the third group were positive. Association with anti-phospholipid antibodies was observed twice in leg ulcers. The level of antibodies was higher in patients with leg ulcers. COMMENTS: The presence of high levels of anti-endothelial cells antibodies in 48.5 p. 100 of patients presenting leg ulcers shows that these antibodies are not specific to autoimmune diseases. Since they are involved in coagulation, inflammation (enhancing of adhesion molecules and tissue lysis) and apoptosis of endothelial cells, their significance in chronic ulcers, both as a consequence and/or possible cofactor merits discussion.

Adolescent↗