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John FitzGerald

Publications and source records attributed to John FitzGerald.

8 recordsLinked to original sources
PubMed2006

Antibodies against the activated coagulation factor X (FXa) in the antiphospholipid syndrome that interfere with the FXa inactivation by antithrombin.

Antiphospholipid Ab have been shown to promote thrombosis and fetal loss in the antiphospholipid syndrome (APS). Previously, we found IgG anti-thrombin Ab in some APS patients that could interfere with inactivation of thrombin by antithrombin (AT). Considering that activated coagulation factor X (FXa) is homologous to thrombin in the catalytic domains and is also regulated primarily by AT, we hypothesized that some thrombin-reactive Ab may bind to FXa and interfere with AT inactivation of FXa. To test these hypotheses, we studied reactivity of eight patient-derived monoclonal IgG antiphospholipid Ab with FXa and the presence of IgG anti-FXa Ab in APS patients and investigated the effects of FXa-reactive mAb on AT inactivation of FXa. The results revealed that six of six thrombin-reactive IgG mAb bound to FXa and that the levels of plasma IgG anti-FXa Ab in 38 APS patients were significantly higher than those in 30 normal controls (p < 0.001). When the mean plus 3 SDs of the 30 normal controls was used as the cutoff, 5 of 38 APS patients (13.2%) had IgG anti-FXa Ab. Importantly, three of six FXa-reactive mAb significantly inhibited AT inactivation of FXa. Combined, these results indicate that anti-FXa Ab may contribute to thrombosis by interfering with the anticoagulant function of AT on FXa in some APS patients.

Antibodies, Monoclonal↗
PubMed2006

Proinflammatory high-density lipoprotein as a biomarker for atherosclerosis in patients with systemic lupus erythematosus and rheumatoid arthritis.

OBJECTIVE: Women with systemic lupus erythematosus (SLE) have a 7-50-fold increased risk of coronary artery disease (CAD). In the general population, oxidized low-density lipoprotein (ox-LDL) increases the risk for CAD. Normal high-density lipoproteins (HDLs) protect LDL from oxidation; proinflammatory HDLs do not. This study was undertaken to determine whether patients with SLE, who have chronic inflammation that causes oxidative damage, have more proinflammatory HDL and higher levels of ox-LDL, thus predisposing them to atherosclerosis. METHODS: One hundred fifty-four women with SLE, 48 women with rheumatoid arthritis (RA), and 72 healthy controls were studied. The ability of the patients' HDL to prevent oxidation of normal LDL was measured. Values >1.0 (the value assigned for LDL oxidation in the absence of HDL) after the addition of HDL indicated proinflammatory HDL. Plasma ox-LDL levels were measured as the amount of oxidation produced by the patient's LDL after the removal of HDL. RESULTS: SLE patients had more proinflammatory HDL (mean +/- SD score 1.02 +/- 0.57, versus 0.68 +/- 0.28 in controls [P < 0.0001] and 0.81 +/- 0.22 in RA patients [P = 0.001 versus SLE patients]). A higher proportion of SLE patients had proinflammatory HDL: 44.7% of SLE patients versus 4.1% of controls and 20.1% of RA patients had scores >1.0 (P < 0.006 between all groups). Levels of ox-LDL correlated with levels of proinflammatory HDL (r = 0.37, P < 0.001). SLE patients with CAD had significantly higher proinflammatory HDL scores than patients without CAD (P < 0.001). CONCLUSION: HDLs are proinflammatory in a significant proportion of SLE patients and are associated with elevated levels of ox-LDL. Abnormal HDLs impair the ability to prevent LDL oxidation and may predispose to atherosclerosis.

Adult↗
PubMed2005

Identification of polyclonal and monoclonal antibodies against tissue plasminogen activator in the antiphospholipid syndrome.

OBJECTIVE: To test the hypotheses that some plasmin-reactive anticardiolipin antibodies (aCL) may bind to tissue plasminogen activator (tPA) and that some of the tPA-reactive aCL may inhibit tPA activity. METHODS: We studied the reactivity of 8 patient-derived monoclonal aCL with tPA and examined the presence of IgG anti-tPA antibodies in patients with the antiphospholipid syndrome (APS). The effects of the reactive monoclonal aCL on the activity of tPA were also examined. RESULTS: Six patient-derived plasmin-reactive monoclonal aCL bound to tPA. Analysis of plasma samples revealed that 10 of 80 APS patients (12.5%) and 1 of 81 systemic lupus erythematosus patients (1.2%) had antibodies against fibrin-associated tPA, based on a cutoff value equal to the mean + 2SD of the level in 28 normal subjects. Of the 6 tPA-reactive monoclonal aCL, 2 of them (CL1 and CL15) inhibited tPA activity. CONCLUSION: Some of the plasmin-reactive aCL in APS patients may bind to tPA. Of the tPA-reactive aCL, some (such as CL1 and CL15) may inhibit tPA activity and, thus, may be prothrombotic in the host.

Adult↗
PubMed2004

Identification of anti-plasmin antibodies in the antiphospholipid syndrome that inhibit degradation of fibrin.

The combined presence of anti-phospholipid Ab (aPL) and thrombosis is recognized as the antiphospholipid syndrome (APS). The aPL represent a heterogeneous group of Ab that recognize various phospholipids (PL), PL-binding plasma proteins, and/or PL-protein complexes. Recently, we found the presence of antithrombin Ab in some APS patients and that some of these anti-thrombin Ab could inhibit thrombin inactivation by antithrombin. Considering that thrombin is homologous to plasmin, which dissolves fibrin, we hypothesize that some APS patients may have Ab that react with plasmin, and that some anti-plasmin Ab may interfere with the plasmin-mediated lysis of fibrin clots. To test this hypothesis, we searched for anti-plasmin Ab in APS patients and then studied those found for their effects on the fibrinolytic pathway. The results revealed that seven of 25 (28%) APS patients have IgG anti-plasmin Ab (using the mean OD plus 3 SD of 20 normal controls as the cutoff) and that six of six patient-derived IgG anti-thrombin mAb bind to plasmin with relative K(d) values ranging from 5.6 x 10(-8) to 1 x 10(-6) M. These K(d) values probably represent affinities in the higher ranges known for human IgG autoantibodies against protein autoantigens. Of these mAb, one could reduce the plasmin-mediated lysis of fibrin clots. These findings suggest that plasmin may be an important driving Ag for some aPL B cells in APS patients, and that the induced anti-plasmin Ab may act either directly, by binding to plasmin and inhibiting its fibrinolytic activity, or indirectly, by cross-reacting with other homologous proteins in the coagulation cascade to promote thrombosis.

Amino Acid Sequence↗
PubMed2003

Supply of POMs.

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Animals↗
PubMed2003

Identification and characterization of a peptide mimetic that may detect a species of disease-associated anticardiolipin antibodies in patients with the antiphospholipid syndrome.

OBJECTIVE: To test the feasibility of applying a mimetic (specific for a patient-derived prothrombotic anticardiolipin antibody [aCL]) to study the homologous, disease-associated aCL in patients with antiphospholipid syndrome (APS). METHODS: We used the CL15 monoclonal aCL to screen 17 phage-display peptide libraries. Peptides (corresponding to recurrent peptide sequences) and their derivatives were synthesized and analyzed for binding to CL15 and for their abilities to inhibit CL15 from binding to cardiolipin. A peptide was chosen and used to study CL15-like IgG aCL in plasma samples from patients with APS, patients with systemic lupus erythematosus (SLE) but without APS, and normal healthy donors. RESULTS: Library screening with CL15 yielded 4 recurrent peptide sequences. Analyses of peptides showed that peptide CL154C reacted with antibody CL15 and inhibited binding of CL15 to cardiolipin, indicating that peptide CL154C may be a peptide mimetic for the CL15 aCL. Initial studies with plasma samples revealed that CL154C-reactive IgG was present (positivity defined as the mean + 3 SD optical density of the 25 normal controls) in 15 of 21 APS patients and 1 of 12 SLE patients. CONCLUSION: These findings suggest that it is feasible to develop a specific enzyme-linked immunosorbent assay for each immunologically and functionally distinct disease-associated aCL. Additional testing of CL154C with a larger number of APS patients and SLE patients, as well as identification of peptide mimetics for each distinct aCL, will reveal the diagnostic potential of CL154C and other mimetics in identifying patients with aCL who are at risk of developing life-threatening thrombosis.

Adolescent↗