Pro- and anticoagulant factors facilitate thrombin generation and balance the haemostatic response to FEIBA(®) in prophylactic therapy.

INTRODUCTION: FEIBA(®) consists of zymogens and traces of activated forms of procoagulant factors II, VII, IX, X, anticoagulants protein C and TFPI, and small amounts of cofactors FV, FVIII and protein S, in a balanced ratio. As shown previously, FII-FXa complex plays a key role in FEIBA's mode of action (MoA). METHODS: Thrombin generation (TG) was measured by spiking coagulation factors, cofactors and inhibitors to high titer FVIII inhibitor plasma, and in plasma samples from patients in a phase 3 clinical study evaluating the safety and efficacy of FEIBA prophylaxis in haemophilia A patients with inhibitors. RESULTS: Increasing the FXa/FII ratio improved TG, while adding coagulation enzyme components had a negligible effect. Adding FX, FIX, and FVII increased the peak thrombin and decreased the lag time. The presence of FV and phospholipids led to faster TG, while protein C and protein S reduced the amount of peak thrombin. TFPI appeared to have no effect. Patients on prophylaxis with FEIBA(®) showed higher peak thrombin and AUC with elevated FII, FX, FIX, FVIIa, and protein C levels, and experienced significantly less bleeding episodes than those receiving on-demand treatment. CONCLUSION: These experiments showed that although the FII-FXa complex induced immediate thrombin formation on the activated platelet surface, other procoagulant components of FEIBA were necessary to achieve an optimal thrombin burst. The presence of the pro- and anti-coagulants in FEIBA provides a haemostatic balance, and is thus expected to prevent thrombotic events. Recent clinical data verified the postulated MoA of FEIBA in prophylaxis treatment.

Prophylaxis with anti-inhibitor coagulant complex improves health-related quality of life in haemophilia patients with inhibitors: results from FEIBA NF Prophylaxis Study.

The Pro-FEIBA study reported health-related quality of life (HRQoL) improved following 6-month of Factor Eight Inhibitor Bypassing Activity (FEIBA) prophylaxis. This study investigates whether 12-month of FEIBA prophylaxis improved HRQoL in haemophilia patients with inhibitors. Thirty-six subjects in a 1-year prospective, randomized, open-label, parallel-design study were randomized to prophylaxis (85 ± 15 U kg(-1) every other day) or on-demand treatment. HRQoL was assessed at screening, 6 and 12-month termination using the EQ-5D, Haem-A-QoL, Haemo-QoL and a general pain visual analog scale (VAS). To evaluate changes, paired t-tests and criteria for minimally important differences were applied. Repeated measures regression tested the association between annualized bleeding rate (ABR) and physical HRQoL. At 6 and 12 months, prophylaxis subjects reported clinically meaningful improvement in EQ-5D index (mean improvement, 0.10 and 0.08, respectively) and both clinically meaningful and statistically significant improvements in EQ-VAS scores (16.9 and 15.7, respectively; P < 0.05) vs. baseline. General pain was significantly reduced during prophylaxis at each follow-up (mean improvement, 20.3 and 23.2, respectively; both P <0.05). At 12 months, prophylaxis subjects achieved significant improvements in Haem-A-QoL Total Score and in four domains: Physical Health, Feeling, View, and Work and School (all P < 0.05). No statistically significant changes, except for Haem-A-QoL Physical Health at 6 months, were observed with on-demand treatment. ABR was decreased by 72.5% with prophylaxis vs. on-demand treatment (P = 0.0003) and reduced ABR was associated with better physical HRQoL (P < 0.05). FEIBA prophylaxis significantly reduced ABR and improved HRQoL in inhibitor patients. Subjects with lower ABR reported better physical HRQoL.

Randomized comparison of prophylaxis and on-demand regimens with FEIBA NF in the treatment of haemophilia A and B with inhibitors.

Factor replacement therapy for the treatment of moderate to severe haemophilia A and B can be complicated by the production of inhibitory alloantibodies to factor VIII (FVIII) or factor IX. Treatment with the nanofiltered anti-inhibitor coagulant complex, Factor Eight Inhibitor Bypassing Activity (FEIBA NF), is a key therapeutic option for controlling acute haemorrhages in patients with high-titre inhibitors or low-titre inhibitors refractory to replacement therapy. Given the high risk for morbidity and mortality in haemophilia patients with inhibitors to FVIII or FIX, we conducted this Phase 3 prospective study to evaluate whether prophylaxis with FEIBA NF is a safe and effective treatment option. Over a 1-year period, 17 subjects were treated prophylactically (85 ± 15 U kg(-1) every other day) while 19 subjects were treated on demand. The median (IQR) annualized bleeding rate (ABR) during prophylaxis was 7.9 (8.1), compared to 28.7 (32.3) during on-demand treatment, which amounts to a 72.5% reduction and a statistically significant difference in ABRs between arms (P = 0.0003). Three (17.6%) subjects (ITT) on prophylaxis experienced no bleeding episodes, whereas none treated on demand were bleeding episode-free. Total utilization of FEIBA NF for the treatment of bleeding episodes was significantly higher during on-demand therapy than prophylaxis (P = 0.0067). There were no differences in the rates of related adverse events between arms. This study demonstrates that FEIBA prophylaxis significantly reduces all types of bleeding compared with on-demand treatment, and the safety of prophylaxis is comparable to that of on-demand treatment.

Regulation of expression of aminopeptidase N in fetal rat lung by dexamethasone and epidermal growth factor.

Aminopeptidase N (EC 3.4.11.2) (APN) is an ectopeptidase expressed in lung at the apical surface of alveolar type II epithelial cells. Its expression is up-regulated during fetal lung development. Recently several ectopeptidases have been recognized as possible regulators of growth and cell differentiation through their role in hydrolysis of autocrine and paracrine peptides that influence these processes. The studies reported here describe effects of factors known to promote lung development and differentiation of the alveolar epithelium on expression of aminopeptidase N during fetal lung development in organ culture. Fetal rat lung was placed in organ culture at the 15th gestational day and cultured for 6 days in the presence or absence of the synthetic glucocorticoid hormone dexamethasone or epidermal growth factor (EGF). Steady-state levels of APN mRNA increased approximately 10-fold during the 6-day culture. During this time the lung alveolar epithelium developed to the point where immature alveolar type II cells were recognized by the presence of lamellar bodies. Dexamethasone or EGF increased the levels of APN mRNA in the fetal lung 2-to 3-fold over control cultures by the third day in culture and concurrently accelerated the morphological development of the alveolar epithelium. Differences in treated and control cultures diminished after 6 days in culture when the epithelium appeared more mature, suggesting that the immature epithelium was more responsive to the treatments.

The effect of smoking on serum IgG2 reactive with Actinobacillus actinomycetemcomitans in early-onset periodontitis patients.

High titers of serum IgG2 reactive with Actinobacillus actinomycetemcomitans are present in early-onset periodontitis (EOP) patients and it appears that anti-A. actinomycetemcomitans may be protective. Smoking is associated with increased periodontal disease severity in generalized early-onset periodontitis (G-EOP) patients, but is not associated with periodontal disease severity in patients with localized juvenile periodontitis (LJP). Furthermore, smoking is associated with reduced serum IgG2 levels in black patients with G-EOP but not in those with LJP. Based on this selective effect of smoking, we hypothesized that smoking would be associated with a reduction of specific IgG2 reactive with A. actinomycetemcomitans in black G-EOP patients but not black LJP patients. In addition, we examined IgG2 responses to carbohydrate antigens from non-periodontal pathogens including Haemophilus influenzae b oligosaccharide antigen (Hib) and the Streptococcus pneumoniae antigen phosphocholine (PC). Smoking status was assessed from serum cotinine levels, and IgG2 specific for A. actinomycetemcomitans, Hib, and PC was assessed by ELISA. Our study revealed that smoking was correlated with a dramatic reduction in serum IgG2 anti-A. actinomycetemcomitans in G-EOP smokers but not in LJP smokers. In contrast, anti-Hib IgG2 and anti-PC IgG2 were not affected in either G-EOP or LJP patients. In short, these results indicate that smoking is associated with a reduction in serum IgG2 anti-A. actinomycetemcomitans in black G-EOP subjects, but IgG2 reactive with other antigens may not be reduced in G-EOP smokers.

Ectopeptidases of alveolar epithelium: candidates for roles in alveolar regulatory mechanisms.

This commentary discusses the implications of recent observations indicating that at least one, and probably three, ectopeptidases are exhibited on the surface of alveolar epithelial cells. The unique biological feature of the ectopeptidases is that they are expressed on the surface of only selected cell types and at specific stages in the differentiation of those cells. Consequently they are positioned to exert their enzymatic activity in a very restricted locale. Drawing from information derived from studies of this activity on other cells, we develop the proposition that the ectopeptidases on alveolar epithelial cells regulate the biological activity of peptides encountered at this site. These may be peptides produced by the alveolar epithelial cells or cytokines that have the potential of influencing the alveolar cells. Awareness that these ectopeptidases are expressed on the luminal surface of these cells thus opens heretofore unrecognized avenues of investigation.

p146 type II alveolar epithelial cell antigen is identical to aminopeptidase N.

A prominent membrane protein of rat type II alveolar cells, p146, was originally identified by one of many mouse monoclonal antibodies that were produced to rat lung cells in the course of a search for differentiation antigens that might prove useful in studying lung differentiation. We report here results from analysis of the primary structure of this molecule and, based on this knowledge, the elucidation of the function of the protein. Amino acid sequencing of the NH2-terminal portion of the p146 protein, plus partial sequencing of several peptides obtained by limited proteolysis, indicates it is identical to aminopeptidase N. Further, the immunoaffinity purified p146 protein has aminopeptidase N activity. The discussion includes references to other molecules such as CD 13 and CD 10 (CALLA) that were recognized as differentiation antigens and subsequently found to be peptidases. The possible biological implications of such a peptidase on the luminal surface of type II alveolar cells are also considered.

Expression of aminopeptidase N in fetal rat lung during development.

The ectopeptidase, aminopeptidase N, serves as a cell surface marker of the apical surface of the alveolar type II epithelial cell in adult lung. It is also present in fetal lung before differentiation of morphologically mature type II alveolar epithelial cells, suggesting that it is expressed by precursors of the type II cells. We have examined the mRNA coding for the aminopeptidase in adult and fetal lung and in mature type II cells and determined levels of mRNA and immunoreactive protein during fetal lung development. Comparison of the temporal patterns of steady-state levels of aminopeptidase mRNA and immunoreactive protein during development show that the expression of the protein is developmentally regulated and that expression is regulated, at least in part, at a pretranslational level. Both mRNA and immunoreactive protein levels increase severalfold on the final gestational day, suggesting that the function of the aminopeptidase may be associated with air breathing.

Tobacco and smoking: environmental factors that modify the host response (immune system) and have an impact on periodontal health.

This review summarizes the current data on the effects of smoking and tobacco on the immune system and its potential impact on periodontal health. Smokers are 2.5-6 times more likely to develop periodontal disease than non-smokers, and there is evidence for a direct correlation between the number of cigarettes smoked and the risk of developing disease. Tobacco users also tend to exhibit increased severity of periodontal disease. Direct correlations between tobacco use and increased attachment loss and pocket depth and reduced bone crest height have been reported. Although the correlation between tobacco use and periodontal disease is quite strong, the role of tobacco in the pathogenesis of periodontal disease is uncertain. Recent studies indicate that one potential mechanism is that tobacco use exacerbates periodontal disease because it alters the immune response to periodontal pathogens. Indeed, smokers exhibit increased numbers of peripheral blood mononuclear phagocytes which appear to be functionally compromised. Inadequate phagocyte activity could reduce the clearance of pathogens from the oral cavity and thereby facilitate the development of periodontal disease. Tobacco-exposed B- and T-lymphocytes exhibit reduced proliferative capacities which could limit the production of protective immunoglobulins against oral pathogens. The risk factors for periodontal disease can be broadly classified as genetic, environmental, host-response factors, and host-related factors such as age. Tobacco, an environmental factor, undermines the host response and may facilitate the development and progression of periodontal disease. This review highlights the inter-relatedness of two of the risk factors associated with periodontal disease.