Muscarinic inhibition of salivary glands with glycopyrronium bromide does not reduce the uptake of PSMA-ligands or radioiodine

RATIONALE

Salivary glands are highly perfused and express the prostate-specific membrane antigen (PSMA) receptor as well as the sodium-iodide symporter. As a consequence, treatment with ¹⁷⁷Lu/²²⁵Ac-PSMA for prostate cancer or ¹³¹I for thyroid cancer leads to a high radiation dose in the salivary glands, and patients can be confronted with persistent xerostomia and reduced quality of life. Salivation can be inhibited using an antimuscarinic pharmaceutical, such as glycopyrronium bromide (GPB), which may also reduce perfusion. The primary objective of this work was to determine if inhibition with GPB could provide a considerable (> 30%) reduction in the accumulation of administered ¹²³I or ⁶⁸Ga-PSMA-11 in salivary glands.

METHODS

Ten patients who already received a whole-body ⁶⁸Ga-PSMA-11 PET/CT scan for (re)staging of prostate cancer underwent a repeat PET/CT scan with tracer administration at 90 min after intravenous injection of 0.2 mg GPB. Four patients in follow-up after thyroid cancer, who had been treated with one round of ablative ¹³¹I therapy with curative intent and had no signs of recurrence, received ¹²³I planar scintigraphy at 4 h after tracer administration without GPB and a repeated scan at least one week later, with tracer administration at 30 min after intramuscular injection of 0.4 mg GPB. Tracer uptake in the salivary glands was quantified on PET and scintigraphy, respectively, and values with and without GPB were compared.

RESULTS

No significant difference in PSMA uptake in the salivary glands was seen without or with GPB (Mean SUL_mean parotid glands control 5.57, intervention 5.72, p = 0.50. Mean SUL_mean submandibular glands control 6.25, intervention 5.89, p = 0.12). Three out of 4 patients showed increased ¹²³I uptake in the salivary glands after GPB (Mean counts per pixel control 8.60, intervention 11.46).

CONCLUSION

Muscarinic inhibition of salivation with GPB did not significantly reduce the uptake of PSMA-ligands or radioiodine in salivary glands, and can be dismissed as a potential strategy to reduce toxicity from radionuclide therapies.

[Papillary carcinoma in a thyroglossal duct cyst; diagnostics and treatment]

This is a case review of a 53-year-old female who presented with an asymptomatic thyroglossal duct cyst. Fine needle aspiration cytology was negative for malignant cells. However, CT findings showed a multilocular cyst of 4,4x2,5x4,5 cm with a solid mass of 1,8 cm and calcifications, suggestive for a thyroid carcinoma inside the thyroglossal duct cyst. A Sistrunk procedure was performed and pathology showed a papillary carcinoma inside the thryoglossal duct cyst. The coexistence of carcinomas in thyroglossal duct cysts is extremely rare, with most being papillary carcinomas. The Sistrunk procedure is often regarded as adequate, but controversies exist concerning the need for thyroidectomy and/or neck dissection. Our patient did not receive a thyroidectomy based on her patient- and tumourcharacteristics.

Salvage Surgery for Recurrence after Radiotherapy for Squamous Cell Carcinoma of the Head and Neck

OBJECTIVE

Most studies that report on salvage surgery after primary radiotherapy for head and neck squamous cell carcinoma (HNSCC) are small and heterogeneous. Subsequently, some relevant questions remain unanswered. We specifically focused on (1) difference in prognosis per tumor subsite, corrected for disease stage, and (2) differences in prognosis after salvage surgery for local, regional, and locoregional recurrences.

STUDY DESIGN

Retrospective analysis.

SETTING

Single-center study (2000-2016).

SUBJECTS AND METHODS

Patients treated with salvage surgery for HNSCC recurrence after (chemo)radiotherapy.

RESULTS

In total, 189 patients were included. Five-year overall survival (OS) was 33%, and median OS was 18 (95% confidence interval [CI], 11-26) months. Treatment-related mortality was 2%. Larynx carcinoma was associated with more favorable local (adjusted hazard ratio [HR] = 4.02; 95% CI, 1.46-11.10; P = .007) and locoregional control (adjusted HR = 5.34; 95% CI, 1.83-15.61; P = .002) than pharyngeal carcinoma. American Society of Anesthesiologists (ASA) score (≥3 vs 1-2: adjusted HR = 3.04; 95% CI, 1.17-7.91; P = .023), pT stage (3-4 vs 1-2: adjusted HR = 4.41; 95% CI, 1.65-11.82; P = .003), and salvage surgery for locoregional recurrences (locoregional vs local: adjusted HR = 3.81; 95% CI, 1.13-11.82; P = .021) were independent predictors for disease-free survival (DFS).

CONCLUSION

Salvage surgery for larynx carcinoma, regardless of disease stage and other prognostic factors, results in more favorable loco(regional) control but not favorable DFS than pharyngeal carcinoma. The observed difference in DFS between salvage surgery for local and regional recurrences was not significant after correction for confounders. However, survival following salvage surgery for locoregional disease is significantly worse. For this subgroup, we propose to consider T status and comorbidity for clinical decision making, as high pT stage and ASA score are independent predictors for worse DFS.

PAI-1 Synthesis in the Human Hepatoma Cell Line Hep G2 Is Increased by Cytokines - Evidence that the Liver Contributes to Acute Phase Behaviour of PAI-1

The acute phase behaviour of the fast inhibitor of tissue-type plasminogen activator (PAI-1) in vivo has been attributed to increased synthesis by endothelial cells. However, most other acute phase proteins in vivo are synthesized in the liver, which process is regulated by cytokines and can be studied in the hepatoma derived cell line HepG2.

In this study, we investigated whether the synthesis of PAI-1 by HepG2 cells is regulated by the cytokines recombinant IL-1, rlL-6 and rTNF. Recombinant IL-1 and rTNF each increased PAI-1 synthesis by Hep G2 cells two to three fold, whereas rIL-6 hardly had an effect. Mixtures of rIL-1, rIL-6 and rTNF increased PAI-1 synthesis up to eleven fold. The effects observed were not due to non-specific effects on Hep G2 cell metabolism, since synthesis of alpha-2-antiplasmin was not effected by any of those cytokines, whereas fibrinogen synthesis was increased three to four fold by rIL-6, but was unaffected by rIL-1. Thus, our results demonstrate that synthesis of PAI-1 by Hep G2 cells is regulated by cytokines and implicate that the acute phase behaviour of PAI-1 in vivo at least in part may be due to an increased synthesis by the liver.

[Polycythaemia in a patient with uterus myomatosus]

BACKGROUND

Myomatous erythrocytosis syndrome (MES) is characterised by a combination of polycythaemia, uterus myomatosus and the normalisation of erythrocyte count after hysterectomy.

CASE DESCRIPTION

A 58-year-old postmenopausal woman was referred to the gynaecologist with symptoms of vaginal blood loss, increased abdominal circumference and pollakiuria. Physical examination indicated her uterus was enlarged to the size of a 24-week gestation. Endometrial malignancy was excluded and ultrasound showed a myoma. In consultation with the patient a hysterectomy was planned. Pre-operative blood tests showed increased haemoglobin levels (14.2 mmol/l). No indications of polycythaemia vera or secondary polycythaemia were found after which the diagnosis of MES was made. Haemoglobin levels normalised after hysterectomy without any further intervention.

CONCLUSION

MES is common, although relatively unknown. Its pathophysiology is most likely based on ectopic production of erythropoietin by leiomyoma tissue. The combination of polycythaemia and uterus myomatosus should alert clinicians to this syndrome, especially as polycythaemia normalises after hysterectomy.

Induction chemotherapy with docetaxel/cisplatin/5-fluorouracil followed by randomization to two cisplatin-based concomitant chemoradiotherapy schedules in patients with locally advanced head and neck cancer (CONDOR study) (Dutch Head and Neck Society 08-01): A randomized phase II study

PURPOSE

To study the feasibility of induction chemotherapy added to concomitant cisplatin-based chemoradiotherapy (CRT) in patients with locally advanced head and neck cancer (LAHNC).

PATIENTS AND METHODS

LAHNC patients were treated with 4 courses of docetaxel/cisplatin/5-fluorouracil (TPF) followed by randomization to either cisplatin 100 mg/m(2) with conventional radiotherapy (cis100 + RT) or cisplatin 40 mg/m(2) weekly with accelerated radiotherapy (cis40 + ART). Primary endpoint was feasibility, defined as receiving ≥ 90% of the scheduled total radiation dose. Based on power analysis 70 patients were needed.

RESULTS

65 patients were enrolled. The data safety monitoring board advised to prematurely terminate the study, because only 22% and 41% (32% in total) of the patients treated with cis100 + RT (n = 27) and cis40 + ART (n = 29) could receive the planned dose cisplatin during CRT, respectively, even though the primary endpoint was reached. Most common grade 3-4 toxicity was febrile neutropenia (18%) during TPF and dehydration (26% vs 14%), dysphagia (26% vs 24%) and mucositis (22% vs 57%) during cis100 + RT and cis40 + ART, respectively. For the patients treated with cis100 + RT and cis40 + ART, two years progression free survival and overall survival were 70% and 78% versus 72% and 79%, respectively.

CONCLUSION

After TPF induction chemotherapy, cisplatin-containing CRT is not feasible in LAHNC patients, because the total planned cisplatin dose could only be administered in 32% of the patients due to toxicity. However, all but 2 patients received more than 90% of the planned radiotherapy. Clinical Trials Information: NCT00774319.

Current treatment options for local residual nasopharyngeal carcinoma

OPINION STATEMENT

Local residual disease occurs in 7-13 % after primary treatment for nasopharyngeal carcinoma (NPC). To prevent tumor progression and/or distant metastasis, treatment is indicated. Biopsy is the "gold standard" for diagnosing residual disease. Because late histological regression frequently is seen after primary treatment for NPC, biopsy should be performed when imaging or endoscopy is suspicious at 10 weeks. Different modalities can be used in the treatment of local residual disease. Interestingly, the treatment of residual disease has better outcomes than treatment of recurrent disease. For early-stage disease (rT1-2), treatment results and survival rates are very good and comparable to patients who had a complete response after the first treatment. Surgery (endoscopic or open), brachytherapy (interstitial or intracavitary), external or stereotactic beam radiotherapy, or photodynamic therapy all have very good and comparable response rates. Choice should depend on the extension of disease, feasibility of the treatment, and doctor's and patient's preferences and experience, as well as the risks of the adverse events. For the more extended tumors, choice of treatment is more difficult, because complete response rates are poorer and severe side effects are not uncommon. The results of external beam reirradiation and stereotactic radiotherapy are better than brachytherapy for T3-4 tumors. Photodynamic therapy resulted in good palliative responses in a few patients with extensive disease. Also, chemotherapeutics or the Epstein-Barr virus targeted therapies can be used when curative intent treatment is not feasible anymore. However, their advantage in isolated local failure has not been well described yet. Because residual disease often is a problem in countries with a high incidence of NPC and limited radiotherapeutic and surgical facilities, it should be understood that most of the above mentioned therapeutic modalities (radiotherapy and surgery) will not be readily available. More research with controlled, randomized trials are needed to find realistic treatment options for residual disease.

The pharmacokinetics of ¹³¹I-rituximab in a patient with CD20 positive non-Hodgkin Lymphoma: evaluation of the effect of radioiodination on the biological properties of rituximab

PURPOSE

To report the pharmacokinetics of ¹³¹I-rituximab a patient with a CD20 positive non-Hodgkin Lymphoma who has received ¹³¹I-rituximab as consolidation treatment after remission induction and to evaluate the effect of radioiodination on the biological properties of rituximab.

RESULTS

The patient was a 65-year-old male with a relapsed CD20 positive follicular non-Hodgkin Lymphoma. After induction therapy the patient was in partial remission. Following administration of a diagnostic dose of 185 MBq ¹³¹I-rituximab, remaining lesions were identified on the wholebody scans. The patient then received a therapeutic dose of 1000 MBq ¹³¹I-rituximab. The uptake by the tumor in the right axilla was 0.17-0.21% of the injected dose. The calculated biological half-life of ¹³¹I-rituximab was 684 hrs. This biological half-life corresponded well with the half-life of unlabeled rituximab which was approximately 720 hrs.

DISCUSSION AND CONCLUSION

Even though radioiodination of rituximab results in a reduced binding capacity, whole body scans demonstrated localization of ¹³¹I-rituximab in the tumor area. This observation supports the specific targeting of ¹³¹I-rituximab. The half-life of ¹³¹I-rituximab corresponded to the half-life of unlabeled rituximab. Hence, the pharmacokinetics of ¹³¹ I-rituximab was not relevantly affected by the radioiodination process.

Crosstalk among Bcl-2 family members in B-CLL: seliciclib acts via the Mcl-1/Noxa axis and gradual exhaustion of Bcl-2 protection

Seliciclib (R-roscovitine) is a cyclin-dependent kinase inhibitor in clinical development. It triggers apoptosis by inhibiting de novo transcription of the short-lived Mcl-1 protein, but it is unknown how this leads to Bax/Bak activation that is required for most forms of cell death. Here, we studied the effects of seliciclib in B-cell chronic lymphocytic leukemia (B-CLL), a malignancy with aberrant expression of apoptosis regulators. Although seliciclib-induced Mcl-1 degradation within 4 h, Bax/Bak activation occurred between 16 and 20 h. During this period, no transcriptional changes in apoptosis-related genes occurred. In untreated cells, prosurvival Mcl-1 was engaged by the proapoptotic proteins Noxa and Bim. Upon drug treatment, Bim was quickly released. The contribution of Noxa and Bim as a specific mediator of seliciclib-induced apoptosis was demonstrated via RNAi. Significantly, 16 h after seliciclib treatment, there was accumulation of Bcl-2, Bim and Bax in the 'mitochondria-rich' insoluble fraction of the cell. This suggests that after Mcl-1 degradation, the remaining apoptosis neutralizing capacity of Bcl-2 is gradually overwhelmed, until Bax forms large multimeric pores in the mitochondria. These data demonstrate in primary leukemic cells hierarchical binding and crosstalk among Bcl-2 members, and suggest that their functional interdependence can be exploited therapeutically.

A 57-year-old man who developed arthritis during R-CHOP chemotherapy for non-Hodgkin lymphoma

Rituximab is a chimeric human-mouse anti-CD20 monoclonal antibody, which is used in the treatment of both B-cell lymphomas and rheumatic diseases. We describe a case of a previously healthy 57-year-old man developing arthritis while being treated with rituximab-CHOP chemotherapy (R-CHOP) for a non-Hodgkin lymphoma. The remittant arthritis developed at successively shorter time-intervals after R-CHOP administration and only improved after rituximab was removed from the chemotherapy schedule, suggesting a rituximab-related phenomenon, as extensive diagnostic testing ruled out any other diagnosis.

Effective palliation by low dose local radiotherapy for recurrent and/or chemotherapy refractory non-follicular lymphoma patients

In this work, we have studied the response rates and duration of response after low-dose (4 Gy) involved field radiotherapy (LD-IF-RT) in relapsed or chemotherapy refractory indolent and aggressive lymphoma patients. 71 patients (177 symptomatic sites) received LD-IF-RT consisting of 39 males and 32 females with a median age of 69 years (range 43-93). Patients included were those with small lymphocytic lymphoma/chronic lymphocytic leukaemia (n=23), marginal zone lymphoma, nodal type (n=18), mantle cell lymphoma (n=17), and diffuse large B-cell lymphoma (n=13). Bulky disease (5 cm) was present in 73% of all patients. A median of two prior chemotherapy regimens (range 0-10) preceded LD-IF-RT. Median time since diagnosis was 31 months (range 1-216 months). Time to (local) progression was calculated according to the Kaplan-Meier method. Differences in response rates were compared using the chi2-test. The results showed that overall response rate was 87%; complete remission (CR) was reached in 34 patients (48%) and a partial remission (PR) in 28 patients (39%). Stable disease (SD) was maintained in nine patients (13%). The median time to progression (TP) was 12 months and the median time to local progression (TLP) was 22 months. The 34 CR patients showed a median TP of 16 months and a median TLP of 23 months. None of the factors studied (age, sex, lymphoma subtype, radiotherapy regimen, number of prior regimens or time since diagnosis, number of positive sites or largest lymphoma diameter) were found to relate to response. At time of death 70% of patients were without in-field progression after LD-IF-RT. It appears that LD-IF-RT is a valuable asset in the management of relapsed disease in both indolent and aggressive lymphoma and should be considered to palliate symptoms in patients with recurrent and/or chemotherapy refractory disease.

Alpha-2-macroglobulin functions as an inhibitor of fibrinolytic, clotting, and neutrophilic proteinases in sepsis: studies using a baboon model

Alpha-2-macroglobulin (alpha 2M) may function as a proteinase inhibitor in vivo. Levels of this protein are decreased in sepsis, but the reason these levels are low is unknown. Therefore, we analyzed the behavior of alpha 2M in a baboon model for sepsis. Upon challenge with a lethal (4 baboons) or a sublethal (10 baboons) dose of Escherichia coli, levels of inactivated alpha 2M (i alpha 2M) steadily increased, the changes being more pronounced in the animals that received the lethal dose. The rise in i alpha 2M significantly correlated with the increase of thrombin-antithrombin III, plasmin-alpha 2-antiplasmin, and, to a lesser extent, with that of elastase-alpha 1-antitrypsin complexes, raising the question of involvement of fibrinolytic, clotting, and neutrophilic proteinases in the inactivation of alpha 2M. Experiments with chromogenic substrates confirmed that thrombin, plasmin, elastase, and cathepsin G indeed had formed complexes with alpha 2M. Changes in alpha 2M similar to those observed in the animals that received E. coli occurred in baboons challenged with Staphylococcus aureus, indicating that alpha 2M formed complexes with the proteinases just mentioned in gram-positive sepsis as well. We conclude that alpha 2M in this baboon model for sepsis is inactivated by formation of complexes with proteinases, derived from activated neutrophils and from fibrinolytic and coagulation cascades. We suggest that similar mechanisms may account for the decreased alpha 2M levels in clinical sepsis.

Activation of the complement system in baboons challenged with live Escherichia coli: correlation with mortality and evidence for a biphasic activation pattern

Activation of the complement system was studied in baboons that were challenged with live Escherichia coli. In the group challenged with a lethal dose (n = 4), the complement activation parameters C3b/c, C4b/c, and C5b-9 increased 13, 5, and 12 times the baseline value, respectively, during the first 6 h after the E. coli infusion, whereas in the group challenged with a sublethal dose (n = 10), they increased only moderately, by 2 to 3 times the baseline value. However, in this latter group, a more pronounced activation occurred at 24 h. Subsequent experiments showed that this second phase in complement activation started at 6 h after the challenge, at which time infused microorganisms had been cleared from the circulation. The simultaneous increase in C-reactive protein with this second phase suggested an endogenous activation mechanism involving this acute-phase protein. Levels of inactivated (modified) C1 inhibitor also increased in both groups, with peak levels of 2.5 times the baseline value at 24 h in the sublethal group and of 4 times at 6 h after the challenge in the lethal group. Thus, activation of complement in this animal model for sepsis occurs in a biphasic pattern, the initial phase mediated by the bacteria and the later phase mediated by an endogenous mechanism possibly involving C-reactive protein. The differences in complement activation between animals with lethal or sublethal sepsis support the hypothesis that complement activation contributes to the lethal complications of sepsis.

Controlled insect-sting challenge in 55 patients: correlation between activation of plasminogen and the development of anaphylactic shock

The pathogenesis of anaphylactic shock is not completely understood. Mast cell degranulation products may stimulate endothelial cells, leading to activation of fibrinolytic and coagulation systems. We investigated the activation of these systems in insect-sting anaphylaxis. Fifty-five patients with a previous insect-sting anaphylactic reaction and 8 volunteers were challenged with an in-hospital sting. Plasma levels of von Willebrand factor (vWF), coagulation, and fibrinolytic parameters were assessed. After the sting challenge, 20 patients developed anaphylactic symptoms, 7 of whom developed hypotension. In only these 7 patients, but not in the volunteers or in the other patients with no or mild anaphylactic symptoms, vWF levels increased from 107% +/- 33% (mean +/- SD) before, to 235% +/- 134% 60 minutes after the onset of clinical symptoms. This increase of vWF was accompanied by an increase of circulating tissue-type plasminogen-activator (tPA) levels from 5 +/- 3 micrograms/L to 50 +/- 59 micrograms/L and of plasminogen-alpha 2-antiplasmin complex (PAP-c) levels from 6 +/- 3 nmol/L to 297 +/- 225 nmol/L. Both tPA and PAP-c levels peaked 5 minutes after the onset of clinical symptoms. Such increases of tPA and PAP-c were not observed in the volunteers or in the patients who did not develop shock. The increase of tPA and PAP-c levels in the hypotensive patients correlated positively with the degree of mast cell degranulation and inversely with the mean arterial pressure. We conclude that activation of plasminogen may be involved in the pathogenesis of anaphylactic shock induced by insect venom.

pH and Glucose Profiles in Aggregates of Bacillus laevolacticus

Size distributions and glucose and pH profiles of aggregates of the d -(-)-lactic acid-producing organism Bacillus laevolacticus were measured. The organisms were grown in continuous culture with a medium glucose concentration of either 280 or 110 mM. A maximal aggregate diameter of 2.2 mm, with a Sauter mean of 1.46 mm, was determined for the former culture condition, whereas aggregates from a culture with 110 mM glucose input had a maximal diameter of 1.9 mm (Sauter mean of 1.07 mm). A pH gradient of approximately 2 U was observed for large aggregates (above 1.5 mm). In smaller aggregates (0.75 mm), the pH value in the interior part was approximately 0.4 U lower than that in the culture fluid. It could be concluded that, in cultures with the high glucose input, lactic acid accumulated within the aggregates to such an extent that metabolism in the central region of the larger aggregates could not proceed further. In these cultures, approximately 90% of the total biomass was active. In aggregates from cultures with a low glucose input, glucose only partly penetrated the larger-sized aggregates, and the activity of this culture was reduced to approximately 70% of the biomass. These aggregates were found to decrease in size after prolonged periods of cultivation. It is suggested that this is caused by glucose depletion in the interior of the aggregates. It is concluded that the availability of glucose is an important factor in determining the size of aggregates of B. laevolacticus.

Assessment of the relative contribution of different protease inhibitors to the inhibition of plasmin in vivo

It has been shown that the most important inhibitor of plasmin is alpha 2-antiplasmin, however, other protease inhibitors are able to inhibit this proteolytic enzyme as well. The contribution of the various protease inhibitors to the inhibition of plasmin in vivo has never been quantitatively assessed. To assess the relative contribution of the different protease inhibitors on the inhibition of plasmin we developed a series of sensitive immunoassays for the detection of complexes between plasmin and the protease inhibitors alpha 2-antiplasmin, alpha 2-macroglobulin, antithrombin III, alpha 1-antitrypsin and C1-inhibitor, utilizing monoclonal antibodies that are specifically directed against complexed protease inhibitors and a monoclonal antibody against plasmin. It was confirmed that alpha 2-antiplasmin is the most important inhibitor of plasmin in vivo, however, complexes of plasmin with alpha 2-macroglobulin, antithrombin III, alpha 1-antitrypsin- and C1-inhibitor were also detected. Particularly during activation of fibrinolysis complexes between plasmin and inhibitors other than alpha 2-antiplasmin were detected. It was observed that during different situations the inhibition profile of plasmin was not constant e.g. in patients with diffuse intravascular coagulation plasma levels of plasmin-alpha 1-antitrypsin and plasmin-C1-inhibitor were increased whereas in plasma from patients who were treated with thrombolytic agents complexes of plasmin with alpha 2-macroglobulin and with antithrombin III were significantly elevated. In conclusion, we confirmed the important role of alpha 2-antiplasmin in the inhibition of plasmin, however, in situations in which fibrinolysis is activated other protease inhibitors also account for the inhibition of plasmin in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Clearance of human native, proteinase-complexed, and proteolytically inactivated C1-inhibitor in rats

C1-inhibitor is the only known inhibitor of the classical pathway of complement and the major inhibitor of the contact pathway of coagulation. Like other serine proteinase inhibitors, C1-inhibitor can exist in three conformations, ie, the native, the proteinase-complexed, and the proteolytically inactivated form. Here we studied the plasma elimination kinetics of these three forms of human C1-inhibitor in rats. The clearance of the complexed form of C1-inhibitor appeared to be the most rapid and depended in part on the proteinase involved (observed plasma t1/2 was 20 minutes for C1s-C1-inhibitor, 32 minutes for kallikrein-C1-inhibitor, and 47 minutes for beta XIIa-C1-inhibitor), whereas that of native C1-inhibitor was the slowest (observed plasma t1/2 4.5 hours). Inactivated C1-inhibitor was cleared with an apparent plasma t1/2 of 1.6 hours. Thus, the short plasma t1/2 of complexed relative to native C1-inhibitor explains why in patients only low concentrations of C1-inhibitor complexes may be observed despite activation of the contact and/or complement systems.

Activation patterns of coagulation and fibrinolysis in baboons following infusion with lethal or sublethal dose of Escherichia coli

Administration of low doses endotoxin or tumor necrosis factor (TNF) in human experimental models for sepsis results in transient activation of both coagulation and fibrinolysis and subsequent inhibition of the fibrinolytic system by plasminogen activator inhibitor type 1 (PAI-1). We have investigated in a baboon model for sepsis, whether administration of a lethal or sublethal dose of living E. coli could induce similar activation patterns. Levels of thrombin-antithrombin III (TAT) complexes increased significantly to zeniths of 425 and 33 times the baseline values at t+360 in the lethal and sublethal group, respectively. Activation of fibrinolysis, as reflected by plasmin-alpha 2 antiplasmin (PAP) complexes, in the sublethal group was maximal at t+60 and was increasingly inhibited thereafter in spite of a sustained increase of tissue type plasminogen activator (t-PA) levels. In the lethal group PAP complexes increased to a zenith of 38 times the baseline values at t+240. PAI-1 levels increased to 15 times the baseline values at t+360 in the sublethal group, whereas in the lethal group they increased almost linearly to 20 times the baseline values at t+360. Despite high levels of PAI-1, effective inhibition of the fibrinolysis was not established until at T+240 in the lethal group. The difference in activation patterns of both mediator systems in the sublethal and lethal group of baboons indicate that extensive activation of coagulation contributes to the lethal complications in sepsis.

Generation of plasmin during acute attacks of hereditary angioedema

Hereditary angioedema is caused by a genetic deficiency of C1-inhibitor, a serine protease inhibitor that regulates activation of complement, contact, and fibrinolytic systems. Symptoms (bouts of subcutaneous and mucous swelling) depend on the release of a vasoactive mediator, probably through activation of these three systems. We studied the interrelationship among complement, contact, and fibrinolytic activation in 23 patients with hereditary angiodema, 18 during remission and five during an attack, by measuring plasma levels of C1-C1 inhibitor, factor XIIa-C1 inhibitor, kallikrein-C1 inhibitor, and plasmin-alpha 2-antiplasmin complexes, tissue plasminogen activator, and urokinase plasminogen activator. In addition, cleavage of high-molecular weight kininogen was detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and quantified by densitometry. During remission, plasma levels of C1-C1 inhibitor complexes were elevated (p = 0.0002), whereas the other parameters were within the normal range. During acute attacks, not only plasma levels of C1-C1 inhibitor complexes but also those of plasmin-alpha 2-antiplasmin complexes (P = 0.0009) and cleaved high-molecular weight kininogen were elevated. A positive correlation between plasmin-alpha 2-antiplasmin complexes and cleaved high-molecular weight kininogen was observed (r = 0.75, p < 0.001). This article presents the first in vivo evidence that supports the concept that release of vasoactive mediators in hereditary angiodema attacks is associated with the activation of the fibrinolytic system.

Coagulation disorders in septic shock

Abnormalities in coagulation and fibrinolysis are frequently observed in septic shock. The most pronounced clinical manifestation is disseminated intravascular coagulation. Recent studies in human volunteers and animal models have clarified the early dynamics and route of activation of both coagulation and fibrinolytic pathways. In healthy subjects subjected to a low dose of either endotoxin or TNF an imbalance in the procoagulant and the fibrinolytic mechanisms is apparent, resulting in a procoagulant state. Also in patients with septic shock a dynamic process of coagulation and fibrinolysis is ongoing with evidence of impaired fibrinolysis. These abnormalities have prognostic significance; the extent of disturbances of coagulation and fibrinolysis is related to the development of multiple organ failure and death.

Interleukin-2 induces activation of coagulation and fibrinolysis: resemblance to the changes seen during experimental endotoxaemia

The administration of Interleukin-2 (IL-2) causes the release or generation of other cytokines such as tumour necrosis factor (TNF) which, by disturbing the anticoagulant properties of the endothelium, may induce a procoagulant state in patients receiving this drug. We therefore evaluated the effects of IL-2 on coagulation and fibrinolysis in 14 patients receiving 12 or 18 x 10(6) IU/m2/d of IL-2 given as a 15 min infusion for 5 d. Blood samples were drawn at short intervals after the first IL-2 infusion. The parameters were analysed by way of analysis for repeated measures (F tests rather than t tests). During the first day, thrombin-antithrombin (TAT) complexes started to increase 2 h after the IL-2 infusion, reaching peak levels at 4 h (n = 14; 11.2 +/- 6.4 micrograms/l v 49.8 +/- 49.2 micrograms/l, P < 0.01). Plasma alpha 2 antiplasmin (PAP) complexes showed a similar pattern rising from a mean baseline value of 17.5 +/- 7.6 nmol/l to 66.8 +/- 47.7 nmol at 4 h (P < 0.01). In four patients the peak of PAP preceeded that of TAT. Tissue plasminogen activator (tPA) rose from a mean baseline value of 4.9 +/- 3.7 micrograms/l to 26.3 +/- 13.5 micrograms/l at 4 h (P < 0.01). Plasminogen-activator-inhibitor-1 (PAI-1) levels increased from 59 +/- 35 micrograms/l to 113 +/- 39 micrograms/l at 6 h (P < 0.01). tPA PAI-1 complexes increased from 0.15 +/- 0.07 to 0.69 +/- 0.21 nmol/l at 6 h (P < 0.01). Our study indicates that IL-2 activates the coagulation and fibrinolytic systems in vivo. The changes resemble the perturbations observed after endotoxin/TNF administration. These abnormalities may play a role in the side-effects induced by IL-2 therapy.

Interplay of complement and cytokines in the pathogenesis of septic shock

Sepsis is a clinical syndrome that is usually induced by bacterial infections. It is generally assumed that the syndrome results from an excessive triggering of endogenous inflammatory mediators by the invading microorganisms. These mediators include substances released by activated monocytes, macrophages, endothelial cells and neutrophils such as cytokines, reactive oxygen species and proteases, as well as activation products of coagulation, fibrinolysis, contact and complement systems. Recent studies have suggested that cytokines and complement activation products may have overlapping biological activities. In addition, multiple interactions in vitro as well as in vivo between cytokines and complement have been described. Here we will review some of these recent studies and will discuss their relevance for the pathogenesis of sepsis and septic shock.

Analysis of intraarticular fibrinolytic pathways in patients with inflammatory and noninflammatory joint diseases

OBJECTIVE

Intraarticular activation of the fibrinolytic system has been suspected to occur in patients with arthritis. We undertook the present study to investigate the relation of this activation to clinical symptoms, and the molecular pathways involved.

METHODS

We quantitatively assessed levels of plasmin-alpha 2-antiplasmin (PAP) complexes in synovial fluid (SF) from 25 patients with rheumatoid arthritis (RA), 7 with seronegative spondylarthropathy (SSA), and 10 with osteoarthritis (OA), and conducted an analysis to determine the plasminogen-activating pathway via which these complexes were generated. In addition, we studied the relationship of intraarticular fibrinolysis to clinical and biochemical parameters.

RESULTS

All patients studied had increased SF levels of PAP complexes. Levels in patients with RA and SSA were slightly higher than those in patients with OA. These complexes were probably formed by activation of urokinase-type plasminogen activator (u-PA), and not tissue-type plasminogen activator (t-PA), since SF levels of both u-PA antigen and u-PA-plasminogen activator inhibitor (PAI) complexes were increased in 27 of the 42 patients. Conversely, SF levels of t-PA were below normal in all but 1 patient. In some patients, activation of factor XII presumably also contributed to plasminogen activation in SF, since levels of factor XIIa-C1 inhibitor in SF were increased in 8 of the 42 patients and correlated, as did u-PA-PAI levels, with levels of PAP complexes. Several of the parameters of fibrinolysis in SF, particularly u-PA antigen and u-PA-PAI-1 complexes, were found to correlate with clinical and biochemical parameters.

CONCLUSION

Our results suggest that plasminogen is frequently activated in the joints of patients with inflammatory or noninflammatory arthropathy and that this activation mainly occurs via a u-PA-, and in some cases also via a factor XII-, dependent pathway. The possible relation of this activation process to stimulation of synovial cells by cytokines is discussed.

Plasminogen activation in vivo upon intravenous infusion of DDAVP. Quantitative assessment of plasmin-alpha 2-antiplasmin complex with a novel monoclonal antibody based radioimmunoassay

Infusion of desamino-d-arginine vasopressin (DDAVP) results in an increase in plasma plasminogen activator activity. Whether this increase results in the generation of plasmin in vivo has never been established. A novel sensitive radioimmunoassay (RIA) for the measurement of the complex between plasmin and its main inhibitor alpha 2-antiplasmin (PAP complex) was developed using monoclonal antibodies preferentially reacting with complexed and inactivated alpha 2-antiplasmin and monoclonal antibodies against plasmin. The assay was validated in healthy volunteers and in patients with an activated fibrinolytic system. Infusion of DDAVP in a randomized placebo controlled crossover study resulted in all volunteers in a 6.6-fold increase in PAP complex, which was maximal between 15 and 30 min after the start of the infusion. Hereafter, plasma levels of PAP complex decreased with an apparent half-life of disappearance of about 120 min. Infusion of DDAVP did not induce generation of thrombin, as measured by plasma levels of prothrombin fragment F1+2 and thrombin-antithrombin III (TAT) complex. We conclude that the increase in plasminogen activator activity upon the infusion of DDAVP results in the in vivo generation of plasmin, in the absence of coagulation activation. Studying the DDAVP induced increase in PAP complex of patients with thromboembolic disease and a defective plasminogen activator response upon DDAVP may provide more insight into the role of the fibrinolytic system in the pathogenesis of thrombosis.

Reduction of contact activation related fibrinolytic activity in factor XII deficient patients. Further evidence for the role of the contact system in fibrinolysis in vivo

In this study the contribution of activation of the contact system to activation of the fibrinolytic system in vivo was investigated in healthy volunteers and in factor XII deficient patients. The plasminogen activating activity in plasma from healthy volunteers after infusion of desamino D-arginine vasopressin (DDAVP) was only partially blocked (for 77%) with specific antibodies to tissue-type plasminogen activator and urokinase type plasminogen activator. The residual activity could be quenched by a monoclonal antibody that inhibits factor XII activity and was not present in patients with a factor XII deficiency. The formation of plasmin upon the DDAVP stimulus as reflected by circulating plasmin-alpha 2-antiplasmin complexes was lower in factor XII deficient patients than in healthy volunteers. Activation of the contact system occurred after DDAVP infusion in healthy volunteers and was absent in factor XII deficient patients. These results indicate that DDAVP induces a plasminogen activating activity that is partially dependent on activation of the contact system and that contributes to the overall fibrinolytic activity as indicated by the formation of plasmin-alpha 2-antiplasmin complexes. This fibrinolytic activity is impaired in factor XII deficient patients which may explain the occurrence of thromboembolic complications in these patients.

Fibrinolytic response to tumor necrosis factor in healthy subjects

Tumor necrosis factor (TNF) may be involved in the disturbance of the procoagulant-fibrinolytic balance in septicemia, leading to microvascular thrombosis. To assess the dynamics of the fibrinolytic response to TNF in humans, we performed a crossover saline-controlled study in six healthy men, investigating the effects of a bolus intravenous injection of recombinant human TNF (50 micrograms/m2) on the stimulation and inhibition of plasminogen activation as well as on plasmin activity and inhibition. TNF induced a brief fourfold increase in the overall plasma plasminogen activator (PA) activity peaking after 1 h (p less than 0.0001), which was associated with rises in the antigenic levels of urokinase-type plasminogen activator (p less than 0.0001) and tissue-type plasminogen activator (p less than 0.0001). Plasminogen activator inhibitor type I antigen remained unchanged in the first hour, but showed a rapid eightfold increase thereafter (p less than 0.0001), which coincided with the decrease in PA activity. Generation of plasmin activity in the first hour was signified by an 11-fold rise in D-dimer levels (p less than 0.0001); inhibition of plasmin was reflected by a 36-fold rise in plasmin-alpha 2 antiplasmin complexes (p less than 0.0001), as well as by a transient 16% decrease in alpha 2-antiplasmin activity (p less than 0.01). In conclusion, TNF induced an early activation of the fibrinolytic system becoming maximal in 1 h, with a rapid inhibition thereafter. Earlier observations in the same subjects showed sustained coagulation activation for 6-12 h. The observed disbalance between the procoagulant and fibrinolytic mechanisms after TNF injection confirms the in vivo relevance of the effects of TNF on vascular endothelium in vitro and may explain the tendency towards microvascular thrombosis in septicemia.

The interaction of plasminogen activator inhibitor 1 with plasminogen activators (tissue-type and urokinase-type) and fibrin: localization of interaction sites and physiologic relevance

Plasminogen activator inhibitor 1 (PAI-1), an essential regulatory protein of the fibrinolytic system, harbors interaction sites for plasminogen activators (tissue-type [t-PA] and urokinase-type [u-PA]) and for fibrin. In this study, anti-PAI-1 monoclonal antibodies (MoAbs) were used to identify interaction sites of PAI-1 with these components. The binding sites of 18 different MoAbs were established and are located on five distinct "linear" areas of PAI-1. MoAbs, binding to two distinct areas of PAI-1, are able to prevent the inhibition of t-PA by PAI-1. In addition, two interaction sites for fibrin were identified on PAI-1. The area located between amino acids 110 and 145 of PAI-1 contains a binding site for both components and its significance is discussed in the context of the t-PA inhibition by fibrin-bound PAI-1. Subsequently, the MoAbs were used to assess the role of platelet-PAI-1 in clot-lysis. An in vitro clot-lysis system was used to demonstrate that clot-lysis resistance is dependent on the presence of activated platelets and that PAI-1 is a major determinant for lysis-resistance. We propose that, upon activation of platelets, PAI-1 is fixed within the clot by binding to fibrin and retains its full capacity to inhibit t-PA and u-PA.

PAI-1 synthesis in the human hepatoma cell line HepG2 is increased by cytokines--evidence that the liver contributes to acute phase behaviour of PAI-1

The acute phase behaviour of the fast inhibitor of tissue-type plasminogen activator (PAI-1) in vivo has been attributed to increased synthesis by endothelial cells. However, most other acute phase proteins in vivo are synthesized in the liver, which process is regulated by cytokines and can be studied in the hepatoma derived cell line HepG2. In this study, we investigated whether the synthesis of PAI-1 by HepG2 cells is regulated by the cytokines recombinant IL-1, rIL-6 and rTNF. Recombinant IL-1 and rTNF each increased PAI-1 synthesis by HepG2 cells two to three fold, whereas rIL-6 hardly had an effect. Mixtures of rIL-1, rIL-6 and rTNF increased PAI-1 synthesis up to eleven fold. The effects observed were not due to non-specific effects on HepG2 cell metabolism, since synthesis of alpha-2-antiplasmin was not effected by any of those cytokines, whereas fibrinogen synthesis was increased three to four fold by rIL-6, but was unaffected by rIL-1. Thus, our results demonstrate that synthesis of PAI-1 by HepG2 cells is regulated by cytokines and implicate that the acute phase behaviour of PAI-1 in vivo at least in part may be due to an increased synthesis by the liver.