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Protein Z levels and unexplained fetal losses

2004; Elsevier BV; Volume: 82; Issue: 4 Linguagem: Inglês

10.1016/j.fertnstert.2004.03.049

1556-5653

Elvira Grandone, Donatella Colaizzo, Filomena Cappucci, Nicola Cocomazzi, Maurizio Margaglione,

Cardiovascular Issues in Pregnancy

We evaluated protein Z plasma levels in a group of women with fetal losses (n = 124) and compared them with those in a group of women (n = 60) with uneventful pregnancies. We found that protein Z deficiency is not associated with otherwise unexplained fetal losses. We evaluated protein Z plasma levels in a group of women with fetal losses (n = 124) and compared them with those in a group of women (n = 60) with uneventful pregnancies. We found that protein Z deficiency is not associated with otherwise unexplained fetal losses. Protein Z is a vitamin K-dependent glycoprotein with an important role in the regulation of the coagulation cascade because of a serpin called protein Z-dependent protease inhibitor (ZPI). In the presence of protein Z, ZPI causes fast inactivation of factor Xa (1Han X. Fiehler R. Broze Jr, G.J. Isolation of a protein Z-dependent plasma protease inhibitor.Proc Natl Acad Sci U S A. 1998; 95: 9250-9255Crossref PubMed Scopus (127) Google Scholar). The only described function of protein Z is to serve as a cofactor to enhance the inhibition of factor Xa by ZPI. Protein Z and ZPI circulate as a complex, and in normal plasma, which contains an excess of ZPI, all the protein Z is bound to ZPI. In mice, the protein Z null genotype is prothrombotic and dramatically reduces the survival of Factor V Leiden mice. Recently, it has been suggested that protein Z might have a role in early fetal losses (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar).We carried out a study to evaluate protein Z levels in a group of women with early recurrent fetal loss or intrauterine fetal death.From March 1999 to February 2003, 453 women were consecutively referred to our unit because of recurrent fetal loss or at least one intrauterine fetal death. Women underwent a workup to identify known causes of fetal loss, as previously described (3Grandone E. Margaglione M. Colaizzo D. d'Addedda M. Cappucci G. Vecchione G et al.Factor V Leiden is associated with repeated and recurrent fetal losses.Thromb Haemost. 1997; 77: 822-824PubMed Google Scholar). Only women with a history of recurrent (n = 3) early unexplained fetal loss, defined as the occurrence of fetal loss before 14 weeks' gestational age, or at least one late fetal death (≥20 weeks) entered the study. At the end of the workup, women with known causes of fetal loss were excluded (n = 271). Moreover, women with inherited (Factor V Leiden or FII A20210 mutations, protein C, protein S, or antithrombin deficiency) or acquired (antiphospholipid antibodies) thrombophilia (n = 38), as well as those with previous thromboembolic disease, were excluded (n = 3). Thus, 141 women were eligible, but blood samples were available only for 124. Mean (± SD) age was 32 ± 5.3 years. The study was carried out after approval of the institutional review board of “Casa Sollievo della Sofferenza” Hospital.Blood samples were obtained at least 2 months after the last fetal demise (16.5 ± 26.7 months). Blood samples were collected in 3.8% trisodium citrate and centrifuged at 2000 × g for 15 minutes to obtain platelet-poor plasma, which was immediately frozen and stored in small aliquots at −70°C until tested.Protein Z plasma levels were evaluated by ELISA (Asserachrom Protein Z, Diagnostica Stago, Parsippany, NJ) and are expressed in μg/mL as mean ± 1 SD. In the whole sample, 94 of 124 women (75.8%) were primary aborters (no previous live births) with otherwise unexplained fetal loss, and 30 (24.2%) were secondary aborters. Fifty women (40.3%) had events only before 10 weeks' gestational age, 42 (33.9%) after the beginning of the 10th week, and 29 (25%) had events both before and after 10 weeks' gestational age.Protein Z values were 1.37 ± 0.73 μg/mL in the whole group, 1.41 ± 0.74 μg/mL in the group with primary recurrent miscarriages before 10 weeks, 1.34 ± 0.82 μg/mL in the group with fetal losses after the beginning of the 10th week, and 1.32 ± 0.59 μg/mL in women with events occurring in both periods (Fig. 1). These differences were not statistically significant (Kruskal-Wallis test). Moreover, no significant difference (Scheffé test) was observed when each group was compared with a reference group from the same ethnic background, composed of 60 women with uneventful pregnancies (mean age 29 ± 4.3 years; protein Z values: 1.43 ± 0.76 μg/mL). Twenty-nine women suffered from fetal loss at different periods of pregnancy. We also analyzed data on the basis of the contemporary presence in the obstetric history of fetal loss in different gestational ages. No significant difference in protein Z values was observed among different groups.We are not able to confirm data recently published by Gris et al. (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar), although we used similar selection criteria and have analyzed data with the same categories. However, our data are in agreement with a more recent report (4Hopmeier P. van Trotsemburg M. Dossenbach-Glanicher A. Recurrent pregnancy loss between the 8th and the 15th week of gestation is not associated with an increased frequency of protein Z deficiency.J Thromb Haemostas. 2003; 1 ([abstract]): P0865PubMed Google Scholar). Unlike the study by Gris et al., we excluded women with known inherited or acquired thrombophilias and those with thrombotic antecedents. Moreover, mean values in our controls were different from those measured in some studies (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar, 5Vasse M. Guegan-Massardier E. Borg J.Y. Woimant F. Soria C. Frequency of protein Z deficiency in patients with ischemic stroke.Lancet. 2001; 357: 933-934Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar, 6Miletich J.P. Broze Jr, G.J. Human plasma protein Z antigen: range in normal subjects and effects of warfarin therapy.Blood. 1987; 69: 1580-1586Crossref PubMed Google Scholar) but are in agreement with others (4Hopmeier P. van Trotsemburg M. Dossenbach-Glanicher A. Recurrent pregnancy loss between the 8th and the 15th week of gestation is not associated with an increased frequency of protein Z deficiency.J Thromb Haemostas. 2003; 1 ([abstract]): P0865PubMed Google Scholar, 7Ravi S. Mauron T. Lämmle B. Wuillemin W.A. Protein Z in healthy human individuals and in patients with bleeding tendency.Br J Haematol. 1998; 102: 1219-1223Crossref PubMed Scopus (49) Google Scholar, 8McQuillan A.M. Eikelboom J.W. Hankey G.J. Baker R. Thom J. Staton J et al.Protein Z in ischemic stroke and its etiologic subtypes.Stroke. 2003; 34: 2415-2419Crossref PubMed Scopus (69) Google Scholar), including a study in a different Italian setting (9Sofi F. Fedi S. Tellini I. Cesari F. De Brogi D. Marcucci R et al.Protein Z levels in acute coronary syndromes.J Thromb Haemostas. 2003; 1 ([abstract]): P0507PubMed Google Scholar).Genetic factors might be an important determinant of the wide normal range of protein Z plasma concentrations and might explain inconsistencies among the findings (10Vasse M. Denoyelle C. Legrand E. Vannier J.P. Soria C. Weak regulation of protein Z biosynthesis by inflammatory cytokines.Thromb Haemostas. 2002; 87: 350-351PubMed Google Scholar).We conclude that in our group of patients, protein Z deficiency is not associated with otherwise unexplained fetal losses. Further investigations are needed to shed light on whether protein Z deficiency is associated with a history of unexplained fetal loss in a specific subset of women. Protein Z is a vitamin K-dependent glycoprotein with an important role in the regulation of the coagulation cascade because of a serpin called protein Z-dependent protease inhibitor (ZPI). In the presence of protein Z, ZPI causes fast inactivation of factor Xa (1Han X. Fiehler R. Broze Jr, G.J. Isolation of a protein Z-dependent plasma protease inhibitor.Proc Natl Acad Sci U S A. 1998; 95: 9250-9255Crossref PubMed Scopus (127) Google Scholar). The only described function of protein Z is to serve as a cofactor to enhance the inhibition of factor Xa by ZPI. Protein Z and ZPI circulate as a complex, and in normal plasma, which contains an excess of ZPI, all the protein Z is bound to ZPI. In mice, the protein Z null genotype is prothrombotic and dramatically reduces the survival of Factor V Leiden mice. Recently, it has been suggested that protein Z might have a role in early fetal losses (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar). We carried out a study to evaluate protein Z levels in a group of women with early recurrent fetal loss or intrauterine fetal death. From March 1999 to February 2003, 453 women were consecutively referred to our unit because of recurrent fetal loss or at least one intrauterine fetal death. Women underwent a workup to identify known causes of fetal loss, as previously described (3Grandone E. Margaglione M. Colaizzo D. d'Addedda M. Cappucci G. Vecchione G et al.Factor V Leiden is associated with repeated and recurrent fetal losses.Thromb Haemost. 1997; 77: 822-824PubMed Google Scholar). Only women with a history of recurrent (n = 3) early unexplained fetal loss, defined as the occurrence of fetal loss before 14 weeks' gestational age, or at least one late fetal death (≥20 weeks) entered the study. At the end of the workup, women with known causes of fetal loss were excluded (n = 271). Moreover, women with inherited (Factor V Leiden or FII A20210 mutations, protein C, protein S, or antithrombin deficiency) or acquired (antiphospholipid antibodies) thrombophilia (n = 38), as well as those with previous thromboembolic disease, were excluded (n = 3). Thus, 141 women were eligible, but blood samples were available only for 124. Mean (± SD) age was 32 ± 5.3 years. The study was carried out after approval of the institutional review board of “Casa Sollievo della Sofferenza” Hospital. Blood samples were obtained at least 2 months after the last fetal demise (16.5 ± 26.7 months). Blood samples were collected in 3.8% trisodium citrate and centrifuged at 2000 × g for 15 minutes to obtain platelet-poor plasma, which was immediately frozen and stored in small aliquots at −70°C until tested. Protein Z plasma levels were evaluated by ELISA (Asserachrom Protein Z, Diagnostica Stago, Parsippany, NJ) and are expressed in μg/mL as mean ± 1 SD. In the whole sample, 94 of 124 women (75.8%) were primary aborters (no previous live births) with otherwise unexplained fetal loss, and 30 (24.2%) were secondary aborters. Fifty women (40.3%) had events only before 10 weeks' gestational age, 42 (33.9%) after the beginning of the 10th week, and 29 (25%) had events both before and after 10 weeks' gestational age. Protein Z values were 1.37 ± 0.73 μg/mL in the whole group, 1.41 ± 0.74 μg/mL in the group with primary recurrent miscarriages before 10 weeks, 1.34 ± 0.82 μg/mL in the group with fetal losses after the beginning of the 10th week, and 1.32 ± 0.59 μg/mL in women with events occurring in both periods (Fig. 1). These differences were not statistically significant (Kruskal-Wallis test). Moreover, no significant difference (Scheffé test) was observed when each group was compared with a reference group from the same ethnic background, composed of 60 women with uneventful pregnancies (mean age 29 ± 4.3 years; protein Z values: 1.43 ± 0.76 μg/mL). Twenty-nine women suffered from fetal loss at different periods of pregnancy. We also analyzed data on the basis of the contemporary presence in the obstetric history of fetal loss in different gestational ages. No significant difference in protein Z values was observed among different groups. We are not able to confirm data recently published by Gris et al. (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar), although we used similar selection criteria and have analyzed data with the same categories. However, our data are in agreement with a more recent report (4Hopmeier P. van Trotsemburg M. Dossenbach-Glanicher A. Recurrent pregnancy loss between the 8th and the 15th week of gestation is not associated with an increased frequency of protein Z deficiency.J Thromb Haemostas. 2003; 1 ([abstract]): P0865PubMed Google Scholar). Unlike the study by Gris et al., we excluded women with known inherited or acquired thrombophilias and those with thrombotic antecedents. Moreover, mean values in our controls were different from those measured in some studies (2Gris J.C. Quèrè I. Dechaud H. Mercier E. Pincon C. Hoffet M et al.High frequency of protein Z deficiency in patients with unexplained early fetal loss.Blood. 2002; 99: 2606-2608Crossref PubMed Scopus (100) Google Scholar, 5Vasse M. Guegan-Massardier E. Borg J.Y. Woimant F. Soria C. Frequency of protein Z deficiency in patients with ischemic stroke.Lancet. 2001; 357: 933-934Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar, 6Miletich J.P. Broze Jr, G.J. Human plasma protein Z antigen: range in normal subjects and effects of warfarin therapy.Blood. 1987; 69: 1580-1586Crossref PubMed Google Scholar) but are in agreement with others (4Hopmeier P. van Trotsemburg M. Dossenbach-Glanicher A. Recurrent pregnancy loss between the 8th and the 15th week of gestation is not associated with an increased frequency of protein Z deficiency.J Thromb Haemostas. 2003; 1 ([abstract]): P0865PubMed Google Scholar, 7Ravi S. Mauron T. Lämmle B. Wuillemin W.A. Protein Z in healthy human individuals and in patients with bleeding tendency.Br J Haematol. 1998; 102: 1219-1223Crossref PubMed Scopus (49) Google Scholar, 8McQuillan A.M. Eikelboom J.W. Hankey G.J. Baker R. Thom J. Staton J et al.Protein Z in ischemic stroke and its etiologic subtypes.Stroke. 2003; 34: 2415-2419Crossref PubMed Scopus (69) Google Scholar), including a study in a different Italian setting (9Sofi F. Fedi S. Tellini I. Cesari F. De Brogi D. Marcucci R et al.Protein Z levels in acute coronary syndromes.J Thromb Haemostas. 2003; 1 ([abstract]): P0507PubMed Google Scholar). Genetic factors might be an important determinant of the wide normal range of protein Z plasma concentrations and might explain inconsistencies among the findings (10Vasse M. Denoyelle C. Legrand E. Vannier J.P. Soria C. Weak regulation of protein Z biosynthesis by inflammatory cytokines.Thromb Haemostas. 2002; 87: 350-351PubMed Google Scholar). We conclude that in our group of patients, protein Z deficiency is not associated with otherwise unexplained fetal losses. Further investigations are needed to shed light on whether protein Z deficiency is associated with a history of unexplained fetal loss in a specific subset of women.