High Dose Celecoxib and Metronomic ‘Low-Dose’ Cyclophosphamide Is Effective Therapy in Patients with Relapsed and Refractory Aggressive Histology NHL.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4622-4622
Author(s):  
Rena Buckstein ◽  
M. Crump ◽  
Y. Shaked ◽  
D. Spaner ◽  
E. Piliotis ◽  
...  

Abstract Background: Relapsed aggressive histology non-Hodgkin’s lymphoma (NHL) has a poor prognosis, and new treatments are needed. Angiogenesis is increased in aggressive NHL and may be a target in these diseases. Low-dose chronic chemotherapy (metronomic chemotherapy, MC) inhibits angiogenesis in vitro and in vivo. Since COX-2 may promote neoplasia and tumor angiogenesis, selective COX-2 inhibitors may have antitumor effects in NHL. We assessed response and toxicity to MC and COX-2 inhibition in patients (pts.) with relapsed aggressive NHL following anthracycline-based chemotherapy. Methods: Pts. with measurable disease and normal renal function received cyclophosphamide 50 mg po qd + celecoxib 400 mg po bid. Pts. were assessed clinically and radiologically in serial fashion. We measured serial plasma VEGF and TSP-1 levels and pharmacokinetics (PK) were performed in selected pts. Serial circulating endothelial cells (CEC) and their precursors (CEP) were measured by flow cytometry as of October 2003. Results: To date, 29 of a planned 32 pts. have been enrolled; 3 are ineligible and 25 are evaluable for response. Median age: 62 y (range 22–83). Histology: 17 DLBCL, 1 MCL, 3 transformed (CLL+FL), 2 T cell, 3 anaplastic large cell. Median 2.7 yrs from diagnosis (range 0.5–9.5); Median # of previous chemotherapy regimens: 3 (range 1–6); 31% were chemoresistant to preceding regimen; 8 had undergone prior ASCT. Median time to death or last follow-up: 4 mos (range 0.9–22). Response:10/25 pts. responded (2 CR/CRu, 8 PR, ORR 40%) at a median time of 4.6 mos, and at last f/up, 6/10 remained in PR at 22, 21, 16, 11, 8 and 7 mos. respectively. Three pts. achieved stable disease (SD) but 2 later progressed at a median time of 6 mos (range 4–14 mos) and 12/25 progressed primarily (PD) at a median time of 1.9 mos (range <1–9); 10 have died of NHL (median time 4 mos). 2 partial responders discontinued treatment in PR at 21 and 16 mos for cumulative cyclophosphamide exposure exceeding 40,000 mg. Both progressed within 2–3 months of drug disontinuation. Median OS and PFS are 8.5 and 3.9 mos, respectively. Adverse events (# pts): grade 3–4 ANC (2), grade 3 plt (3), grade 3 hypertension (1), grade 3 atrial arrhythmia(1) and grade 3 drug rash (1). Plasma VEGF and TSP-1 levels do not appear to correlate with response but the number of circulating endothelial cells (CEC) and their precursors (CEP) decline in responders. Celecoxib and cyclophosphamide pharmacokinetics will be presented. This regimen has been well tolerated with minimal GI toxicity. 90% of responders had normal LDH compared with 25% with PD. No patient with preceding chemoresistance responded. Conclusions: MC with high-dose celecoxib and low-dose cyclophosphamide is well tolerated and active in 40% of heavily pre-treated patients with relapsed aggressive NHL. The anti-angiogenic activity of this regimen is still being determined.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3868-3868
Author(s):  
Rachid Baz ◽  
Mohamad Hussein ◽  
Daniel J. Lebovic ◽  
Elizabeth Finley-Oliver ◽  
Mehul P Patel ◽  
...  

Abstract Abstract 3868 Poster Board III-804 Introduction Lenalidomide (Len) is an immunomodulatory drug with antitumor effects mediated through activation of T and NK cells as well as modulation of tumor cytokine environment. Currently Len is approved in combination with dexamethasone (dex) for treatment of patients with relapsed myeloma. Interestingly, in NDMM, higher 1 and 2 year survival rates were observed when the dose of dex was reduced compared to standard high dose dexamethasone and Len (Rajkumar et al. 2008). The immune suppressive effects of dex can antagonize Len immunomodulatory activity and may explain this observation. To our knowledge, Len has not been evaluated as a single agent in NDMM. Patients and methods Records of patients with newly diagnosed symptomatic multiple myeloma treated with single agent Len at H. Lee Moffitt Cancer Center and Roswell Park Cancer Institute were reviewed (after IRB approval at both institutions). Data was collected on disease characteristics, demographics and treatment outcomes. Responses assessed as per the IMWG criteria. Results From March 2007 to July of 2009, 18 patients with NDMM have been treated with Len alone. The median age was 70 years (range 46-84), and 12/18 were males. Heavy chain was IgG in 12 and IgA in 4 patients with 2 patients with light chain myeloma. The involved light chain was kappa in half the patients. Clinical stage of patients included stage IIIA (n=13), IIA (n=4) and IA (n=1) using the DS system whereas as per the ISS system 10, 6 and 2 has stages I, II and III respectively. Cytogenetics were not available on most patients (11); and 4 of 7 patients with available cytogenetics had deletion 13q identified by FISH. The median b2m was 2.8 mg/L (range 2.1-10.7) with >3.5mg/L in 7/18 patients. All except one patient (with a creatinine clearance of 49 ml/min) were started on Len 25 mg daily for 21 days of a 28 days cycle. As of August 1st 2009, 3 patients are inevaluable for response due to short follow up. Among the remainder 15 patients, 3 achieved a CR (1 stringent CR), 2 VGPR, 3 PR, 4 had MR with SD in additional 3 patients. Thus MR or better response was noted in 80% of patients. The median time to first response was 55 days (range 28-98) and median time to best response was 73 days (range 31-591). After a median follow up of 7 months (range 1-26), 1 patient died of progressive disease (despite the addition of dexamethasone and subsequent bortezomib therapy), 4 patients required the addition of dexamethasone. Len was generally well tolerated and no grade 4 hematologic toxicity were noted, 1 patient had grade 3 neutropenia, 1 patients grade 3 anemia and 2 patient grade 3 thrombocytopenia. Four patients had Len dose reduced. Conclusion Single agent Len appears to be an effective therapy in newly diagnosed myeloma patients (MR and better in 80% of patients) and should be evaluated in a prospective fashion in an attempt to decrease corticosteroid toxicity in a group of vulnerable patients and potentially enhance the immunomodulatory activity of Len. Our experience suggests that single agent Len can be effectively employed as an initial step in sequencing anti-myeloma regimen(s) for treatment of NDMM. Disclosures: Baz: celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Off Label Use: lenalidomide as a single agent in newly diagnosed myeloma. Hussein:Celgene: Employment.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Subhashis Paul ◽  
Debabrata Modak ◽  
Sutanuka Chattaraj ◽  
Deblina Nandi ◽  
Aditi Sarkar ◽  
...  

Abstract Background Aloe vera leaf gel has proven efficacious roles in the amelioration of several human diseases and illness-conditions. Specific purified gel-derived bio-constituents as well as the naturally harvested unprocessed A. vera gel have shown promise in modifying systemic inflammation. However, the synergistic role of natural herbal remedies, a mainstay of traditional Indian Ayurveda, has not been evaluated rigorously in this plant. In this study, the prevention of membrane lysis and protein denaturation in the presence of A. vera gel homogenate up to the concentration of 1000 μg/ml of gel has been assessed in vitro. Also, regulation of expression of inflammation-mediator genes (TNF-α and Cox-2) has been investigated in vivo in Freund’s complete adjuvant (FCA)-induced inflammatory arthritic Wistar albino rats in a 28-day long study following the daily oral supplementation of Aloe vera gel homogenate doses up to 0.40 and 0.80 g/kg body weight (low-dose and high-dose groups respectively). Results Our results indicated that A. vera gel homogenate inhibits hypotonicity-induced (74.89 ± 1.26%) and heat-induced (20.86 ± 0.77%) RBC membrane lyses respectively at a concentration of 1000 μg/ml, compared to indomethacin standard (80.52 ± 0.65% and 43.98 ± 1.52% respectively at 200 μg/ml concentration). The similar concentration of gel also showed 39.35 ± 4.25% inhibition of protein denaturation compared to standard diclofenac sodium (46.74 ± 1.84% at 100 μg/ml concentration) in vitro. When assessed in vivo, TNF-α expression was found to be decreased by 35.88% and 38.52%, and Cox-2 expression was found to be decreased by 31.65% and 34.96%, in low-dose and high-dose groups respectively, when compared to the arthritic controls. Conclusions Our findings justify the role of unprocessed A. vera gel homogenate in preventing tissue damage and in the downregulation of TNF-α and Cox-2 gene expressions for the immune-modulation of inflammatory arthritis condition.


2020 ◽  
Vol 22 (1) ◽  
pp. 176
Author(s):  
Toshiaki Iba ◽  
Jerrold H. Levy ◽  
Koichiro Aihara ◽  
Katsuhiko Kadota ◽  
Hiroshi Tanaka ◽  
...  

(1) Background: The endothelial glycocalyx is a primary target during the early phase of sepsis. We previously reported a newly developed recombinant non-fucosylated antithrombin has protective effects in vitro. We further evaluated the effects of this recombinant antithrombin on the glycocalyx damage in an animal model of sepsis. (2) Methods: Following endotoxin injection, in Wistar rats, circulating levels of hyaluronan, syndecan-1 and other biomarkers were evaluated in low-dose or high-dose recombinant antithrombin-treated animals and a control group (n = 7 per group). Leukocyte adhesion and blood flow were evaluated with intravital microscopy. The glycocalyx was also examined using side-stream dark-field imaging. (3) Results: The activation of coagulation was inhibited by recombinant antithrombin, leukocyte adhesion was significantly decreased, and flow was better maintained in the high-dose group (both p < 0.05). Circulating levels of syndecan-1 (p < 0.01, high-dose group) and hyaluronan (p < 0.05, low-dose group; p < 0.01, high-dose group) were significantly reduced by recombinant antithrombin treatment. Increases in lactate and decreases in albumin levels were significantly attenuated in the high-dose group (p < 0.05, respectively). The glycocalyx thickness was reduced over time in control animals, but the derangement was attenuated and microvascular perfusion was better maintained in the high-dose group recombinant antithrombin group (p < 0.05). (4) Conclusions: Recombinant antithrombin maintained vascular integrity and the microcirculation by preserving the glycocalyx in this sepsis model, effects that were more prominent with high-dose therapy.


2014 ◽  
Vol 92 (4) ◽  
pp. 338-349 ◽  
Author(s):  
Kiranj K. Chaudagar ◽  
Anita A. Mehta

Atorvastatin, a lipid lowering agent, possesses various pleiotropic vasculoprotective effects, but its role in coronary angiogenesis is still controversial. Our objective was to study the effects of atorvastatin on the angiogenic responsiveness of coronary endothelial cells (cEC) from normal and diabetic rats. Male Wistar rats were distributed among 9 groups; (i) normal rats, (ii) 30 day diabetic rats, (iii) 60 day diabetic rats, (iv) normal rats administered a low dose of atorvastatin (1 mg/kg body mass, per oral (p.o.), for 15 days); (v) 30 day diabetic rats administered a low dose of atorvastatin; (vi) 60 day diabetic rats administered a low dose of atorvastatin; (vii) normal rats administered a high dose of atorvastatin (5 mg/kg, p.o., for 15 days); (viii) 30 day diabetic rats administered a high dose of atorvastatin; (ix) 60 day diabetic rats administered a high dose of atorvastatin. Each group was further divided into 2 subgroups, (i) sham ischemia–reperfusion and (ii) rats hearts that underwent ischemia–reperfusion. Angiogenic responsiveness the and nitric oxide (NO) releasing properties of the subgroups of cECs were studied using a chorioallantoic membrane assay and the Griess method, respectively. Atorvastatin treatment significantly increased VEGF-induced angiogenic responsiveness and the NO-releasing properties of cECs from all of the subgroups, compared with their respective non-treated subgroups except for the late-phase diabetic rat hearts that underwent ischemia–reperfusion, and the high dose of atorvastatin treatment groups. These effects of atorvastatin were significantly inhibited by pretreatment of cECs with l-NAME, wortmannin, and chelerythrine. Thus, treatment with a low dose of atorvastatin improves the angiogenic responsiveness of the cECs from normal and diabetic rats, in the presence of VEGF, via activation of eNOS–NO release.


2011 ◽  
Vol 55 (12) ◽  
pp. 5480-5484 ◽  
Author(s):  
Yuhan Chang ◽  
Wen-Chien Chen ◽  
Pang-Hsin Hsieh ◽  
Dave W. Chen ◽  
Mel S. Lee ◽  
...  

ABSTRACTThe objective of this study was to evaluate the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with daptomycin, vancomycin, and teicoplanin against methicillin-susceptibleStaphylococcus aureus(MSSA), methicillin-resistantStaphylococcus aureus(MRSA), and vancomycin-intermediateStaphylococcus aureus(VISA) strains. Standardized cement specimens made from 40 g PMMA loaded with 1 g (low-dose), 4 g (middle-dose) or 8 g (high-dose) antibiotics were tested for elution characteristics and antibacterial activities. The patterns of release of antibiotics from the cement specimens were evaluated usingin vitrobroth elution assay with high-performance liquid chromatography. The activities of broth elution fluid against differentStaphylococcus aureusstrains (MSSA, MRSA, and VISA) were then determined. The antibacterial activities of all the tested antibiotics were maintained after being mixed with PMMA. The cements loaded with higher dosages of antibiotics showed longer elution periods. Regardless of the antibiotic loading dose, the teicoplanin-loaded cements showed better elution efficacy and provided longer inhibitory periods against MSSA, MRSA, and VISA than cements loaded with the same dose of vancomycin or daptomycin. Regarding the choice of antibiotics for cement loading in the treatment ofStaphylococcus aureusinfection, teicoplanin was superior in terms of antibacterial effects.


2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A766-A766
Author(s):  
Isabelle Le Mercier ◽  
Sunny Sun ◽  
Dongmei Xiao ◽  
Laura Isacco ◽  
Daniel Treacy ◽  
...  

BackgroundT cell responses are tightly regulated and require a constant balance of signals during the different stages of their activation, expansion, and differentiation. As a result of chronic antigen exposure, T cells become exhausted in solid tumors, preventing them from controlling tumor growth.MethodsWe identified a transcriptional signature associated with T cell exhaustion in patients with melanoma and used our proprietary machine learning algorithms to predict molecules that would prevent T cell exhaustion and improve T cell function. Among the predictions, an orally available small molecule, Compound A, was highly predicted.ResultsCompound A was tested in an in vitro T cell Exhaustion assay and shown to prevent loss of proliferation and expression of immune checkpoint receptors. Transcriptionally, Compound A-treated cells looked indistinguishable from conventionally expanded, non-exhausted T cells. However, when assessed in a classical T cell activation assay, Compound A demonstrated dose dependent activity. At low dose, Compound A was immuno-stimulatory, allowing cells to divide further by preventing activation induced cell death. At higher doses, Compound A demonstrated immuno-suppressive activity preventing early CD69 upregulation and T cell proliferation. All together, these observations suggest that Compound A prevented exhaustion with a mechanism of action involving TCR signaling inhibition. While cessation of TCR signaling or rest has been recently associated with improved CAR-T efficacy by preventing or reversing exhaustion during the in vitro manufacturing phase, it is unclear if that mechanism would translate in vivo.Compound A was evaluated in the CT26 and MC38 syngeneic mouse models alongside anti-PD1. At low dose Compound A closely recapitulated anti-PD1 mediated cell behavior changes by scRNA-seq and flow cytometry in CT26 mice. At high dose, Compound A led to the accumulation of naive cells in the tumor microenvironment (TME) confirming the proposed mechanism of action. Low dose treatment was ineffective in MC38 mouse model but a pulsed treatment at high dose also recapitulated anti-PD1 activity in most animals. Importantly, we identified a new T cell population responding to anti-PD1 that was particularly increased in the MC38 mouse model; Compound A treatment also impacted this population.ConclusionsThese data confirm that mild TCR inhibition either suboptimal or fractionated can prevent exhaustion in vivo. However, this approach has a very limited window of activity between immuno-modulatory and immuno-suppressive effects, thereby limiting potential clinical benefit. Finally, these results demonstrate that our approach and platform was able to predict molecules that would prevent T cell exhaustion in vivo.


Biomedicines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1766
Author(s):  
Sin Mun Tham ◽  
Juwita N. Rahmat ◽  
Edmund Chiong ◽  
Qinghui Wu ◽  
Kesavan Esuvaranathan ◽  
...  

This study evaluates a short therapy schedule for bladder cancer using BCG Tokyo. BCG Tokyo was evaluated in vitro using bone marrow derived dendritic cells, neutrophils, RAW macrophages and the murine bladder cancer cell line, MB49PSA, and compared to other BCG strains. BCG Tokyo > BCG TICE at inducing cytokine production. In vivo, high dose (1 × 107 colony forming units (cfu)) and low dose (1 × 106 cfu) BCG Tokyo with and without cytokine genes (GMCSF + IFNα) were evaluated in C57BL/6J mice (n = 12–16 per group) with orthotopically implanted MB49PSA cells. Mice were treated with four instillations of cytokine gene therapy and BCG therapy. Both high dose BCG alone and low dose BCG combined with cytokine gene therapy were similarly effective. In the second part the responsive groups, mice (n = 27) were monitored by urinary PSA analysis for a further 7 weeks after therapy cessation. More mice were cured at day 84 than at day 42 confirming activation of the immune system. Cured mice resisted the re-challenge with subcutaneous tumors unlike naïve, age matched mice. Antigen specific T cells recognizing BCG, HY and PSA were identified. Thus, fewer intravesical instillations, with high dose BCG Tokyo or low dose BCG Tokyo with GMCSF + IFNα gene therapy, can induce effective systemic immunity.


2014 ◽  
Author(s):  
Δημήτριος Λυσίτσας

Εισαγωγή: Η υπερπλασία του έσω χιτώνα παίζει μείζων ρόλο στην επαναστένωση (in-stentrestenosis). Στην παρούσα μελέτη αξιολογήσαμε in vitro την επίδραση της D-24851(κυτταροτοξική ουσία που σταματά τον κυτταρικό κύκλο στο στάδιο G2-M) στονπολλαπλασιασμό των λείων μυϊκών κυττάρων και μελετήσαμε την ασφάλεια και τηνδραστικότητα μίας ενδαγγειακής πρόθεσης (stent) επικαλυμμένης με πολυμερή ουσία πουαπελευθερώνει την D-24851, στην αναστολή της υπερπλασίας του έσω χιτώνα χωρίς ναεμποδίζει την αναγεννητική ικανότητα του ενδοθηλίου σε in vivo πειραματικό μοντέλο.Υλικό και Μέθοδοι: Γυμνά μεταλλικά stent (n=6), stent επικαλυμμένα μόνο με πολυμερήουσία (polymer-coated, n=7) και stent επικαλυμμένα με πολυμερή ουσία πουαπελευθερώνουν 31±1μg (low-dose, n=7), 216±8 μg (high-dose, n=6) ή 1774±39 μg(extreme-dose, n=5) της D-24851 εμφυτεύτηκαν στις μηριαίες αρτηρίες λευκών New Zealandκουνελιών. Τα πειραματόζωα θυσιάστηκαν στις 28 ημέρες για ιστομορφομετρική ανάλυση.Για την αξιολόγηση της ενδοθηλιακής αναγέννησης στις 90 ημέρες, 12 πειραματόζωαχρησιμοποιήθηκαν για την τοποθέτηση polymer-coated (n=3), low dose (n=3), high dose(n=3) or extreme dose (n=3) ενδαγγειακών προθέσεων.Αποτελέσματα: In vitro η D-24851 αναστέλλει την υπερπλασία των λείων μυϊκών κυττάρωνκαι επάγει την απόπτωση τους χωρίς να αυξάνει την επαγωγή της heat shock protein 70(HSP-70), μία κυτταροπροστατευτική και αντι-αποπτωτική πρωτεΐνη. Η θεραπεία με lowdoseD-24851 stents συνδυάστηκε με 38% (P=0.029) μείωση της υπερπλαστικής περιοχήςτου έσω χιτώνα και 35% (P=0.003) μείωση της επι τοις εκατό στένωσης του αυλού σεσύγκριση με τα γυμνά μεταλλικά stents. Ο τραυματισμός και η φλεγμονή του αρτηριακού τοιχώματος δεν παρουσίασαν σημαντικές διαφορές μεταξύ των ομάδων. Τα επικαλυμμέναμόνο με πολυμερή ουσία stents εμφάνισαν παρόμοια ανάπτυξη νεοιστού σε σύγκριση με ταγυμνά μεταλλικά stents. Ωστόσο, όλες οι ομάδες των stents με D-24851 παρουσίασαν ατελήενδοθηλιοποίηση συγκρινόμενα με τα polymer-coated stents.Συμπεράσματα: Οι επικεκαλυμμένες ενδαγγειακές προσθέσεις με πολυμερή ουσία καιχαμηλη δόση D-24851 μειώνουν σημαντικά την υπερπλασιά του έσω χιτώνα. Λόγω τηςατελούς ενδοθηλιοποίησης, μακράς διάρκειας μελέτες είναι απαραίτητες για ναπιστοποιήσουν ότι η αναστολή του νεοιστού παραμένει και μετά τις 28 ημέρες.


2009 ◽  
Vol 77 (12) ◽  
pp. 5612-5622 ◽  
Author(s):  
T. Eoin West ◽  
Thomas R. Hawn ◽  
Shawn J. Skerrett

ABSTRACT Melioidosis is a tropical disease endemic in southeast Asia and northern Australia caused by the gram-negative soil saprophyte Burkholderia pseudomallei. Although infection is often systemic, the lung is frequently involved. B. thailandensis is a closely related organism that at high doses causes lethal pneumonia in mice. We examined the role of Toll-like receptors (TLRs), essential components of innate immunity, in vitro and in vivo during murine B. thailandensis pneumonia. TLR2, TLR4, and TLR5 mediate NF-κB activation by B. thailandensis in transfected HEK293 or CHO cells. In macrophages, TLR4 and the adaptor molecule MyD88, but not TLR2 or TLR5, are required for tumor necrosis factor alpha production induced by B. thailandensis. In low-dose airborne infection, TLR4 is needed for early, but not late, bacterial containment, and MyD88 is essential for control of infection and host survival. TLR2 and TLR5 are not necessary to contain low-dose infection. In high-dose airborne infection, TLR2 deficiency confers a slight survival advantage. Lung and systemic inflammatory responses are induced by low-dose inhaled B. thailandensis independently of individual TLRs or MyD88. These findings suggest that redundancy in TLR signaling or other MyD88-dependent pathways may be important in pneumonic B. thailandensis infection but that MyD88-independent mechanisms of inflammation are also activated. TLR signaling in B. thailandensis infection is substantially comparable to signaling induced by virulent B. pseudomallei. These studies provide additional insights into the host-pathogen interaction in pneumonic Burkholderia infection.


2005 ◽  
Vol 93 (04) ◽  
pp. 743-750 ◽  
Author(s):  
Sarah Horn ◽  
Siegfried Lang ◽  
Kenji Fukudome ◽  
Adriane Nahrup ◽  
Ursula Hoffmann ◽  
...  

SummaryProstacyclin (PGI2) has beneficial cytoprotective properties, is a potent inhibitor of platelet aggregation and has been reported to improve microcirculatory blood flow during sepsis. The formation of PGI2 in response to proinflammatory cytokines is catalysed by the inducible cyclooxygenase (COX) isoform COX-2. Recombinant human activated protein C (rhAPC, drotrecogin alfa (activated)) was shown to have multiple biological activities in vitro and to promote resolution of organ dysfunction in septic patients. Whether rhAPC exerts its beneficial effects by modulating prostanoid generation is unknown up to now. It was therefore the aim of the study to examine the in vitro effect of rhAPC on COX-2-mRNA-expression and PGI2 release from human umbilical vein endothelial cells (HUVEC). We found that rhAPC, at supra-therapeutical concentrations (500ng/ml-20μg/ ml), upregulated the amount of COX-2-mRNA in HUVEC at t=3–9h and caused a time- and dose-dependent release of 6-keto PGF1α, the stable hydrolysis product of prostacyclin. RhAPC further increased the stimulating effect of tumor necrosis factor-α (TNF-α) and thrombin on COX-2-mRNA-levels. Transcript levels of cyclooxygenase-1 (COX-1) and prostagland-in I2 synthase, however, were unaffected by the stimulation with rhAPC or thrombin. The upregulatory effect on COX2-mRNA levels was specific for rhAPC since the zymogen protein C in equimolar concentrations had no effect on COX-2-mRNA-levels or 6keto PGF1α-release. Western Blot analysis revealed an increase of COX-2-protein content in HUVEC after treatment with rhAPC. As shown by experiments using monoclonal antibodies against the thrombin receptor PAR-1 (mAb=ATAP2) and against the endothelial protein C receptor (EPCR; mAb=RCR-252), the effect of rhAPC on COX-2-mRNA up-regulation was mediated by binding to the EPCR-receptor and signaling via PAR-1. These results demonstrate that induction of COX-2-expression is an important response of HUVEC to stimulation with rhAPC and may represent a new molecular mechanism, by which rhAPC promotes upregulation of prostanoid production in human endothelium.


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