Five novel mutations of the protein S active gene (PROS 1) in 8 Norman families

To further elucidate the molecular basis for hereditary thrombophilia, we screened the protein S active gene in 11 families with type I deficiency, using a strategy based on denaturing gradient gel electrophoresis (DGGE) of all the coding sequences. Fragments with an abnormal DGGE pattern were sequenced, and 5 novel mutations were identified in 8 families. The mutations were a 7-nucleotide deletion in exon II, a 4-nucleotide deletion in exon III, a T insertion in exon VII, a C to T transition transforming Leu 259 into Pro and a T to C transition transforming Cys 625 into Arg in 4 families. These mutations were the only sequence variations found in the propositus' gene exons and co-segregated with the plasma phenotype. A total of 28 members of these 8 families were heterozygous for one of the 5 mutations. Twenty-four (58,5%) of the 41 deficient subjects over 18 years of age had clinical thrombophilia, whereas the 13 subjects under 18 were asymptomatic. Of the 28 subjects, 6 (21,5%) were also found to bear the factor V Arg 506 Gln mutation.

Acquired von Willebrand's syndrome associated with decrease of plasminogen activator and its inhibitor during hypothyroidism

OBJECTIVES

In a prospective study we searched for von Willebrand's syndrome during hypothyroidism and investigated the effects of treatment with thyroid hormones on plasma concentrations or activities of the factors involved in von Willebrand's disease in addition to tissue plasminogen activator and plasminogen activator inhibitor 1.

METHODS

Eleven patients with hypothyroidism were tested. Factor VIII coagulant activity (VIIIc), von Willebrand factor (vWf:Ag), von Willebrand factor activity (vWf:RCo), tissue plasminogen activator antigen (tPA) and plasminogen activator inhibitor activity (PAI) was monitored before and after correction of hypothyroidism by hormone supplementation.

RESULTS

Five patients had laboratory evidence of type I von Willebrand's disease. The other six patients had concentrations or activities of the factors involved in von Willebrand's disease within the normal range. In all cases except one, during thyroxin treatment, von Willebrand factors returned to normal if initially low, or increased clearly if initially normal. With the correction of hypothyroidism, an increase of tPA was noted in the eleven patients, associated with a significant increase of PAI.

CONCLUSION

Laboratory evidence of von Willebrand's disease is common during hypothyroidism. Study of plasminogen activator and its inhibitor suggest a decrease of von Willebrand factor synthesis during hypothyroidism.

[Influence of protein S deficiency on the arterial thrombosis risk]

Protein S is the cofactor of activated protein C which, together with the antithrombin system, is a major regulator of coagulation. Congenital protein S deficiency is an important risk factor for venous thrombosis. In this study of 105 patients with protein S deficiency, 64 had one of several thromboembolic accidents, including 14 arterial thrombotic accidents involving the central nervous system or the myocardium. These accidents occurred in young subjects (mean age: 25 +/- 13 years) only one-third of whom had another risk factor. This high frequency of arterial thrombosis associated with protein S deficiency calls for a prospective study in young subject with cerebral vascular accident or myocardial infarction.

Increased expression of u-PA and u-PAR on monocytes by LDL and Lp(a) lipoproteins--consequences for plasmin generation and monocyte adhesion

Monocyte-derived foam cells figure prominently in rupture-prone regions of atherosclerotic plaque. As urokinase/urokinase-receptor (u-PA/u-PAR) is the trigger of a proteolytic cascade responsible for ECM degradation, we have examined the effect of atherogenic lipoproteins on monocyte surface expression of u-PAR and u-PA. Peripheral blood monocytes, isolated from 10 healthy volunteers, were incubated with 10 to 200 microg/ml of native or oxidised (ox-) atherogenous lipoproteins for 18 h and cell surface expression of u-PA and u-PAR was analysed by flow cytometry. Both LDL and Lp(a) induced a dose-dependent increase in u-PA (1.6-fold increase with 200 microg/ml of ox-LDL) and u-PAR [1.7-fold increase with 200 microg/ml of ox-Lp(a)]. There is a great variability of the response among the donors, some of them remaining non-responders (absence of increase of u-PA or u-PAR) even at 200 microg/ml of lipoproteins. In positive responders, enhanced u-PA/u-PAR is associated with a significant increase of plasmin generation ( .9-fold increase with 200 microg/ml of ox-LDL), as determined by an amidolytic assay. Furthermore, monocyte adhesion to vitronectin and fibrinogen was significantly enhanced by the lipoproteins [respectively 2-fold and 1.7-fold increase with 200 microg/ml of ox-Lp(a)], due to the increase of micro-PAR and ICAM-1, which are receptors for vitronectin and fibrinogen. These data suggest that atherogenous lipoproteins could contribute to the development of atheromatous plaque by increasing monocyte adhesion and trigger plaque weakening by inducing ECM degradation.

COVID-19 critique et anticorps anti-Interféron : série de 11 cas

Introduction

La survenue de formes sévères ou critiques de COVID-19, avec nécessité d’une hospitalisation en réanimation, est associée à la présence d’anticorps anti-Interféron de classe I dans environ 10 % des cas [1]. Ces anticorps identifiés dans le contexte de la COVID-19 bloquent les molécules d’interféron (IFN) et expliqueraient chez ces patients, la survenue d’une atteinte grave de COVID-19, avec une absence d’élimination précoce du virus SARS-CoV-2. Ainsi, il s’agirait d’une forme de déficit immunitaire, acquis, dirigé contre le virus SARS-CoV-2 mais aussi potentiellement contre d’autres virus. Les caractéristiques cliniques, biologiques et morphologiques des patients présentant ces anticorps n’ont pas été décrites précisément, l’évolution des patients n’est pas connue.

Patients et méthodes

Une recherche d’anticorps anti-Interféron a été réalisée chez des patients ayant été pris en charge en réanimation à l’hôpital Bégin, à l’hôpital Avicenne et à l’hôpital Foch pour une COVID-19. La présence d’anticorps anti-IFNalpha2 et anti-IFNomega étaient recherchée par test ELISA puis confirmée par un test fonctionnel d’inhibition de la phosphorylation de STAT1. Les caractéristiques cliniques des patients ont été relevées à partir des dossiers médicaux. Un suivi médical a été organisé afin de suivre leur évolution sur le plan clinique, biologique et morphologique.

Résultats

Onze patients ont été identifiés. Il s’agissait de 11 hommes. L’âge médian au diagnostic était de 60 ans (min 36 - max 80). Parmi les autres facteurs de risques de COVID-19 grave classiquement identifiés, on retrouvait chez eux, du diabète pour 1 patient, de l’hypertension artérielle pour 6 patients et de l’obésité (IMC > 30 kg/m²) pour 5 patients. L’IMC médian était de 29,8 kg/m² (min 24 - max 32,8). Il n’était pas noté d’antécédent remarquable, notamment pas d’argument pour un déficit immunitaire, pas d’endocrinopathie auto-immune. On retrouvait 1 BPCO, 2 asthmes, 1 coronaropathie et 1 valve aortique mécanique. Au diagnostic de COVID-19, les signes cliniques initiaux habituels de l’infection étaient retrouvés : asthénie (n = 11), fièvre (n= 10), toux (n = 5). Deux patients présentaient des diarrhées et 2 de l’insuffisance rénale aiguë, modérée. Chez 2 patients, on notait une embolie pulmonaire sur le scanner initial. L’évolution était marquée par une aggravation justifiant une admission en réanimation après une médiane de 7 jours (min 3 - max 12), pour une forme sévère chez 2 patients avec au maximum une oxygénothérapie au masque à haute concentration jusqu’à 15L/min pour 1 patient et 4L/min pour 1 autre. Une forme critique survenait chez 9 patients, avec recours à une intubation oro-trachéale pour ventilation mécanique pour 7 cas, une oxygénothérapie nasale à haut débit (OPTIFLOW) était suffisante dans 2 cas. Des pneumopathies bactériennes documentées nécessitaient une antibiothérapie spécifique dans 6 cas. Dans 10 cas, des traitements à visée spécifique du COVID-19 étaient entrepris : corticothérapie (n = 4), hydroxychloroquine (n = 4), lopinavir/ritonavir (n = 3) et tocilizumab (n = 2). En raison du développement d’un SDRA sévère, des séances d’optimisation de l’oxygénothérapie par décubitus ventral étaient entreprises chez 5 patients, avec nécessité d’un recours à une ECMO véno-veineuse pour le jeune patient de 36 ans. Afin d’éliminer les Ac antiIFN, ce dernier a également bénéficié avec succès de 3 séances d’échanges plasmatiques. Au total, 9 patients ont survécu, la durée médiane d’hospitalisaiton en réanimation était de 16 jours (min 2 - max 31). Les 2 décès sont intervenus après limitation thérapeutique pour SDRA réfractaire. Avec un suivi médian de 4,2 mois (min 1 - max 11,2), on note une bonne évolution chez l’ensemble des patients survivants, aucune réinfection n’a été observée et une régression quasi complète des lésions pulmonaires scanographiques (n = 4/5) était retrouvée à 3 mois. Lors du dernier bilan réalisé, il n’était pas constaté d’anomalie de la NFS (n = 7/8), ni syndrome inflammatoire (n = 6/7) et le taux d’immunoglobulines était normal (4/4).

Conclusion

Cette série de cas donne une première description des patients ayant présenté une forme critique de COVID-19 avec Ac anti-IFN de classe I. En dehors de la faible prévalence de comorbidités, il ne semble pas y avoir de phénotype clinique particulier chez cette population en dehors de la prédominance masculine.

Potent activity of peripheral blood lymphocytes in inducing hepatocyte stimulating factor and urokinase in monocytes

As fibrinogen is an independent risk factor for arterial thrombosis we were interested in analysing the mechanism controlling fibrinogen biosynthesis. In this work, we showed that incubation of monocytes with lymphocytes increased hepatocyte stimulating factor (HSF) production. Different mechanisms are involved and our results demonstrated that this effect is in part mediated by an increase in interleukin 6 (IL-6) production. However, IL-6 cannot account for the whole effect and other cytokines could be implicated. In addition, we observed a stimulation of urokinase-type plasminogen activator (u-PA) associated with monocytes when these cells were incubated with lymphocytes for 18 h at 37 degrees C. By producing fragment D (fibrinogen degradation product) and D-dimer (fibrin degradation product) this fibrinolytic activity might also contribute to fibrinogen biosynthesis by hepatocytes.

Fibronectin increases the migration induced by stromal cell-derived factor-1 alpha (SDF-1 alpha) in pre-B acute lymphoblastic leukemia cells

The chemokine, stromal cell-derived factor-1 alpha (SDF-1 alpha) and its receptor CXCR-4 (fusin, LESTR) are thought to be involved in the trafficking of hematopoietic progenitors and stem cells, as suggested by the chemotactic effect of SDF-1 alpha on these cells. Gene inactivation studies have shown that both SDF-1 alpha and CXCR-4 are essential for B lymphopoiesis. Migration of leukemic cells may also be dependent on SDF-1 alpha and CXCR-4. Fibronectin (FN) is a component of the extracellular matrix (ECM), and one of the natural supports for cell movement in their bone hematopoietic environment. In the present study, we examined the influence of FN on the chemotactic effect of SDF-1 alpha and on the CXCR-4 expression and function on human precursor-B acute lymphoblastic leukemia (pre-B ALL) cells at sequential stages of development. Fourteen children with pre-B ALL were studied. Their immunophenotypes belonged to the first three stages of B cell differentiation. Despite relatively high levels of CXCR-4 expression at all stages, the responsiveness to SDF-1 alpha, measured as the percentage of migrating cells in the transwell culture system, varied with patients and seems to be less significant for pre-B3 (and pre-B1) than for pre-B2. There was no correlation (r = 0.2) between the SDF-1 alpha induced migration (range: 2.5-39%) and the cell surface density of CXCR-4 (range: 46.5-97.5%). The extracellular matrix protein FN, either coated on the filter (for more than 18 hours) or in soluble form, enhanced the SDF-1 alpha induced migration of pre-B ALL respectively (2 fold and 1.6 fold) without influencing CXCR-4 expression in short term cultures. Therefore, we analyzed the expression of the FN receptors, VLA-4 (CD49d) and VLA-5 (CD49e), by direct immunofluorescence, on these leukemic cells. VLA-4 was strongly expressed in all stages of pre-B ALL (range: 77-97%) while VLA-5 expression was more variable (range: 14-94%), but no correlation with the FN-dependent increased SDF-1 alpha chemotactic effect was noted. In conclusion, the migratory behavior of pre-B leukemic cells in response to SDF-1 alpha partly depends upon the stage of differentiation, and partly upon unexplained patient variability. Our results suggest that several molecules from the extracellular matrix, such as FN, may be implicated in this phenomenon.

Recruitment of primitive peripheral blood cells: synergism of interleukin 12 with interleukin 6 and stem cell factor

Interleukin-12 (IL-12), a heterodimeric cytokine with potent biological activity, was evaluated for effects on proliferation of human immature progenitor cells in vitro. In vitro proliferation of 5-FU-resistant CD34+ (G0) peripheral blood stem cells (PBSC) in response to sequential cytokine stimulation was examined in the presence and absence of 100 ng/ml IL-12. PBSC were found to include a subpopulation of cells that were resistant to 25 microg/ml 5-FU and required a combination of IL-12, IL-6 and SCF for the production of morphologically recognizable clonogenic elements at day 14 in semisolid medium. Furthermore, addition of IL-6 soluble receptor (IL-6Rs) to IL-6 and SCF led to a similar recruitment. We also demonstrated a significant production of IL-6Rs by CD34+ cells stimulated by IL-12. We noted that glucocorticoids and aldosterone, a mineralocorticoid, had a positive effect on recruitment, but neither mineralocorticoid nor glucocorticoids induced IL-6Rs production by CD34+ cells. The recruitment mechanism by steroids seemed to be different from that used by IL-12. These results confirm previous findings which showed the involvement of IL-12 on immature PBSCs and suggest that IL-12 might play a key role in early haemopoiesis.

Incubation of monocytes with adriamycin increases secretion of hepatocyte stimulating factor for fibrinogen biosynthesis

This work provides evidence that the production by monocytes of hepatocyte stimulating factor(s) for fibrinogen biosynthesis was dramatically increased when monocytes were exposed to Adriamycin. This effect was related to an increased production of leukaemia inhibiting factor (LIF), a cytokine known to stimulate fibrinogen biosynthesis by hepatic cells. Adriamycin also induces an increase in membrane-associated urokinase on monocytes. These results are consistent with the clinical observation in patients with ovarian cancer that when the CA-125 tumour marker decreases during chemotherapy, an increased level of D-dimer is a marker of good prognosis.

Fibrinogen: a vascular risk factor, why? Contributing effect of oncostatin M on both fibrinogen biosynthesis by hepatocytes and participation in atherothrombotic risk related to modifications of endothelial cells

Fibrinogen is a vascular risk factor. We suggest that it is a marker of cytokine secretion that simultaneously stimulates fibrinogen biosynthesis and vascular modifications responsible for atherothrombosis. Among these cytokines, oncostatin M (OSM) is the most potent cytokine for inducing fibrinogen biosynthesis by hepatocytes, and it could contribute to endothelial cell anomalies involved in the atherothrombotic process. Here we show that OSM acts (1) by inducing the secretion involved in invasion of the vessel wall by monocytes; (2) by inducing angiogenesis it promotes plaque destabilization, rupture, and consequently thrombosis; and (3) by decreasing fibrinolysis on macrovascular endothelial cells.

Cerivastatin, an inhibitor of HMG-CoA reductase, inhibits urokinase/urokinase-receptor expression and MMP-9 secretion by peripheral blood monocytes--a possible protective mechanism against atherothrombosis

It is now recognised that acute myocardial infarction results from the rupture of atherosclerotic plaques. Lymphocytes and macrophages, which infiltrate rupture sites, contribute to plaque degradation by expressing urokinase (u-PA) bound to cell membrane by urokinase receptor (u-PAR) and by secreting metalloproteinase MMP-9. We have previously demonstrated that the uptake of oxidised LDL (ox-LDL) by monocytes induces an increase of u-PA and u-PAR expression. The present study shows that the expression of u-PA and u-PAR induced by ox-LDL on monocyte surface is suppressed by cerivastatin (a synthetic inhibitor of HMG-CoA reductase, Bayer) from 2 nM. This leads to reduced plasmin generation and monocyte adhesion to vitronectin. Furthermore, higher concentrations of cerivastatin (50-100 nM) reduce the expression of u-PA and u-PAR on unstimulated monocytes. It also inhibits MMP-9 secretion but has no effect on TIMP-1 secretion, suggesting that the decrease in MMP-9 has a real protective effect on plaque stabilisation. The inhibitory effect of cerivastatin on u-PA expression and MMP-9 secretion can be explained by the inhibition of NF-kappa B translocation into the nucleus, as shown by immunofluorescence. As farnesyl-pyrophosphate reverses the effect of cerivastatin, it is postulated that these effects could also be due to the inhibition of Ras prenylation. This was confirmed by confocal microscopy, which shows the Ras delocalisation from the monocyte membrane. The cerivastatin-induced effects on monocyte functions could explain, at least in part, the protective effect of this drug against atherothrombotic events.