Publications by authors named "Peter Probst"

22 Publications

  • Page 1 of 1

Safety and pharmacodynamics of dalazatide, a Kv1.3 channel inhibitor, in the treatment of plaque psoriasis: A randomized phase 1b trial.

PLoS One 2017 19;12(7):e0180762. Epub 2017 Jul 19.

Kineta Inc., Seattle, WA, United States of America.

Background: Dalazatide is a specific inhibitor of the Kv1.3 potassium channel. The expression and function of Kv1.3 channels are required for the function of chronically activated memory T cells, which have been shown to be key mediators of autoimmune diseases, including psoriasis.

Objective: The primary objective was to evaluate the safety of repeat doses of dalazatide in adult patients with mild-to-moderate plaque psoriasis. Secondary objectives were to evaluate clinical proof of concept and the effects of dalazatide on mediators of inflammation in the blood and on chronically activated memory T cell populations.

Methods: Patients (n = 24) were randomized 5:5:2 to receive dalazatide at 30 mcg/dose, 60 mcg/dose, or placebo twice weekly by subcutaneous injection (9 doses total). Safety was assessed on the basis of physical and neurological examination and laboratory testing. Clinical assessments included body-surface area affected, Psoriasis Area and Severity Index (PASI), and investigator and patient questionnaires.

Results: The most common adverse events were temporary mild (Grade 1) hypoesthesia (n = 20; 75% placebo, 85% dalazatide) and paresthesia (n = 15; 25% placebo, 70% dalazatide) involving the hands, feet, or perioral area. Nine of 10 patients in the 60 mcg/dose group had a reduction in their PASI score between baseline and Day 32, and the mean reduction in PASI score was significant in this group (P < 0.01). Dalazatide treatment reduced the plasma levels of multiple inflammation markers and reduced the expression of T cell activation markers on peripheral blood memory T cells.

Limitations: The study was small and drug treatment was for a short duration (4 weeks).

Conclusion: This study indicates that dalazatide is generally well tolerated and can improve psoriatic skin lesions by modulating T cell surface and activation marker expression and inhibiting mediators of inflammation in the blood. Larger studies of longer duration are warranted.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180762PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5516987PMC
September 2017

A small-molecule IRF3 agonist functions as an influenza vaccine adjuvant by modulating the antiviral immune response.

Vaccine 2017 04 6;35(15):1964-1971. Epub 2017 Mar 6.

Kineta, Inc., 219 Terry Ave. N., Seattle, WA 98109, USA. Electronic address:

Vaccine adjuvants are essential to drive a protective immune response in cases where vaccine antigens are weakly immunogenic, where vaccine antigen is limited, or where an increase in potency is needed for a specific population, such as the elderly. To discover novel vaccine adjuvants, we used a high-throughput screen (HTS) designed to identify small-molecule agonists of the RIG-I-like receptor (RLR) pathway leading to interferon regulatory factor 3 (IRF3) activation. RLRs are a group of cytosolic pattern-recognition receptors that are essential for the recognition of viral nucleic acids during infection. Upon binding of viral nucleic acid ligands, the RLRs become activated and signal to transcription factors, including IRF3, to initiate an innate immune transcriptional program to control virus infection. Among our HTS hits were a series of benzothiazole compounds from which we designed the lead analog, KIN1148. KIN1148 induced dose-dependent IRF3 nuclear translocation and specific activation of IRF3-responsive promoters. Prime-boost immunization of mice with a suboptimal dose of a monovalent pandemic influenza split virus H1N1 A/California/07/2009 vaccine plus KIN1148 protected against a lethal challenge with mouse-adapted influenza virus (A/California/04/2009) and induced an influenza virus-specific IL-10 and Th2 response by T cells derived from lung and lung-draining lymph nodes. Prime-boost immunization with vaccine plus KIN1148, but not prime immunization alone, induced antibodies capable of inhibiting influenza virus hemagglutinin and neutralizing viral infectivity. Nevertheless, a single immunization with vaccine plus KIN1148 provided increased protection over vaccine alone and reduced viral load in the lungs after challenge. These findings suggest that protection was at least partially mediated by a cellular immune component and that the induction of Th2 and immunoregulatory cytokines by a KIN1148-adjuvanted vaccine may be particularly beneficial for ameliorating the immunopathogenesis that is associated with influenza viruses.
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http://dx.doi.org/10.1016/j.vaccine.2017.01.053DOI Listing
April 2017

Krypton-81 in groundwater of the Culebra Dolomite near the Waste Isolation Pilot Plant, New Mexico.

J Contam Hydrol 2014 May 16;160:12-20. Epub 2014 Feb 16.

Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA; Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.

The Waste Isolation Pilot Plant (WIPP) in New Mexico is the first geologic repository for disposal of transuranic nuclear waste from defense-related programs of the US Department of Energy. It is constructed within halite beds of the Permian-age Salado Formation. The Culebra Dolomite, confined within Rustler Formation evaporites overlying the Salado Formation, is a potential pathway for radionuclide transport from the repository to the accessible environment in the human-disturbed repository scenario. Although extensive subsurface characterization and numerical flow modeling of groundwater has been done in the vicinity of the WIPP, few studies have used natural isotopic tracers to validate the flow models and to better understand solute transport at this site. The advent of Atom-Trap Trace Analysis (ATTA) has enabled routine measurement of cosmogenic (81)Kr (half-life 229,000 yr), a near-ideal tracer for long-term groundwater transport. We measured (81)Kr in saline groundwater sampled from two Culebra Dolomite monitoring wells near the WIPP site, and compared (81)Kr model ages with reverse particle-tracking results of well-calibrated flow models. The (81)Kr model ages are ~130,000 and ~330,000 yr for high-transmissivity and low-transmissivity portions of the formation, respectively. Compared with flow model results which indicate a relatively young mean hydraulic age (~32,000 yr), the (81)Kr model ages imply substantial physical attenuation of conservative solutes in the Culebra Dolomite and provide limits on the effective diffusivity of contaminants into the confining aquitards.
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http://dx.doi.org/10.1016/j.jconhyd.2014.02.002DOI Listing
May 2014

Diastolic pulmonary vascular pressure gradient: a predictor of prognosis in "out-of-proportion" pulmonary hypertension.

Chest 2013 Mar;143(3):758-766

Department of Internal Medicine II, Division of Cardiology, Vienna General Hospital, Medical University of Vienna, Vienna, Austria. Electronic address:

Background: Left-sided heart disease (LHD) is the most common cause of pulmonary hypertension (PH). In patients with LHD, elevated left atrial pressure causes a passive increase in pulmonary vascular pressure by hydrostatic transmission. In some patients, an active component caused by pulmonary arterial vasoconstriction and/or vascular remodeling superimposed on left-sided pressure elevation is observed. This “reactive” or “out-of-proportion” PH, defined as PH due to LHD with a transpulmonary gradient (TPG) > 12 mm Hg, confers a worse prognosis. However, TPG is sensitive to changes in cardiac output and left atrial pressure. Therefore, we tested the prognostic value of diastolic pulmonary vascular pressure gradient (DPG) (ie, the difference between invasive diastolic pulmonary artery pressure and mean pulmonary capillary wedge pressure) to better prognosticate death in “out-of-proportion” PH.

Methods: A large database of consecutive cases was analyzed. One thousand ninety-four of 2,351 complete data sets were from patients with PH due to LHD. For proof of concept, available lung histologies were reviewed.

Results: In patients with postcapillary PH and a TPG > 12 mm Hg, a worse median survival (78 months) was associated with a DPG ≥ 7 mm Hg compared with a DPG < 7 mm Hg (101 months, P = .010). Elevated DPG was associated with more advanced pulmonary vascular remodeling.

Conclusions: DPG identifies patients with “out-of-proportion” PH who have significant pulmonary vascular disease and increased mortality. We propose a diagnostic algorithm, using pulmonary capillary wedge pressure, TPG, and DPG in sequence to diagnose pulmonary vascular disease superimposed on left-sided pressure elevation.
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http://dx.doi.org/10.1378/chest.12-1653DOI Listing
March 2013

A novel highly potent therapeutic antibody neutralizes multiple human chemokines and mimics viral immune modulation.

PLoS One 2012 17;7(8):e43332. Epub 2012 Aug 17.

Department of Protein Engineering, VLST Corporation, Seattle, Washington, United States of America.

Chemokines play a key role in leukocyte recruitment during inflammation and are implicated in the pathogenesis of a number of autoimmune diseases. As such, inhibiting chemokine signaling has been of keen interest for the development of therapeutic agents. This endeavor, however, has been hampered due to complexities in the chemokine system. Many chemokines have been shown to signal through multiple receptors and, conversely, most chemokine receptors bind to more than one chemokine. One approach to overcoming this complexity is to develop a single therapeutic agent that binds and inactivates multiple chemokines, similar to an immune evasion strategy utilized by a number of viruses. Here, we describe the development and characterization of a novel therapeutic antibody that targets a subset of human CC chemokines, specifically CCL3, CCL4, and CCL5, involved in chronic inflammatory diseases. Using a sequential immunization approach, followed by humanization and phage display affinity maturation, a therapeutic antibody was developed that displays high binding affinity towards the three targeted chemokines. In vitro, this antibody potently inhibits chemotaxis and chemokine-mediated signaling through CCR1 and CCR5, primary chemokine receptors for the targeted chemokines. Furthermore, we have demonstrated in vivo efficacy of the antibody in a SCID-hu mouse model of skin leukocyte migration, thus confirming its potential as a novel therapeutic chemokine antagonist. We anticipate that this antibody will have broad therapeutic utility in the treatment of a number of autoimmune diseases due to its ability to simultaneously neutralize multiple chemokines implicated in disease pathogenesis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0043332PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3422223PMC
May 2013

Benefit of atrial septal defect closure in adults: impact of age.

Eur Heart J 2011 Mar 12;32(5):553-60. Epub 2010 Oct 12.

Department of Cardiology, Medical University of Vienna, Vienna, Austria.

Aims: To evaluate the effect of age on the clinical benefit of atrial septal defect (ASD) closure in adults.

Methods And Results: Functional status, the presence of arrhythmias, right ventricular (RV) remodelling, and pulmonary artery pressure (PAP) were studied in 236 consecutive patients undergoing transcatheter ASD closure [164 females, mean age of 49 ± 18 years, 78 younger than 40 years (Group A), 84 between 40 and 60 years (Group B) and 74 older than 60 years (Group C)]. Defect size [median 22 mm (inter-quartile range, 19, 26 mm)] and shunt ratio [Qp:Qs 2.2 (1.7, 2.9)] did not differ among age groups. Older patients had, however, more advanced symptoms and both, PAP (r = 0.65, P < 0.0001) and RV size (r = 0.28, P < 0.0001), were significantly related to age. Post-interventionally, RV size decreased from 41 ± 7, 43 ± 7, and 45 ± 6 mm to 32 ± 5, 34 ± 5, and 37 ± 5 mm for Groups A, B, and C, respectively (P < 0.0001), and PAP decreased from 31 ± 7, 37 ± 10, and 53 ± 17 mmHg to 26 ± 5, 30 ± 6, and 43 ± 14 mmHg (P < 0.0001), respectively. Absolute changes in RV size (P = 0.80) and PAP (P = 0.24) did not significantly differ among groups. Symptoms were present in 13, 49, and 83% of the patients before and in 3, 11, and 34% after intervention in Groups A, B, and C. Functional status was related to PAP.

Conclusions: At any age, ASD closure is followed by symptomatic improvement and regression of PAP and RV size. However, the best outcome is achieved in patients with less functional impairment and less elevated PAP. Considering the continuous increase in symptoms, RV remodelling, and PAP with age, ASD closure must be recommended irrespective of symptoms early after diagnosis even in adults of advanced age.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3697806PMC
http://dx.doi.org/10.1093/eurheartj/ehq352DOI Listing
March 2011

PLAATO (Percutaneous Left Atrial Appendage Transcatheter Occlusion) for prevention of cardioembolic stroke in non-anticoagulation eligible atrial fibrillation patients: results from the European PLAATO study.

EuroIntervention 2010 Jun;6(2):220-6

CardioVascular Center Frankfurt, Sankt Katharinen, Frankfurt, Germany.

Aims: The European PLAATO (Percutaneous Left Atrial Appendage Transcatheter Occlusion) study was performed to determine the safety and efficacy of left atrial appendage occlusion by catheter technique. Embolic stroke due to atrial fibrillation is a common observation, especially in the elderly. Most thrombi in atrial fibrillation form in the left atrial appendage (LAA), its occlusion may therefore reduce the incidence of stroke in these patients.

Methods And Results: One hundred and eighty patients with non-rheumatic atrial fibrillation and contraindication to warfarin therapy were enrolled in the PLAATO study. Patients were eligible if they had a?history of transient ischaemic attack (TIA) or stroke or at least two independent risk factors for stroke such as age > or =75 years, hypertension, congestive heart failure or diabetes. The primary endpoint was LAA closure as determined by transesophageal echocardiography (TEE) two months after the procedure and stroke rate at 150 patient years. Left atrial appendage occlusion was successful in 162/180 patients (90%, 95% CI 83.1% to 92.9%). Two patients died within 24 hours of the procedure (1.1%, 95% CI 0.3% to 4%). Six cardiac tamponades were observed (3.3%, 95% CI 1.5% to 7.1%). In two cases, surgical drainage of the tamponade was necessary (1.1%, 95% CI 0.3% to 4%). In one patient, the device that was chosen was too small and embolised into the aorta after its release (0.6%, 95% CI 0.1% to 3.1%). It was snared and replaced without further complications. Successful occlusion of the LAA was achieved in 126/ 140 (90%, 95% CI 83.5% to 94.2%) of patients as noted by TEE at the two months follow-up. In a follow-up time of 129 documented patient years, three strokes occurred (2.3% per year). The expected incidence of stroke according to the CHADS2-Score was 6.6% per year. The trial was halted prematurely during the follow-up phase for financial considerations.

Conclusions: Left atrial appendage closure is relatively safe and effective. However, severe complications can occur. It might become an alternative for atrial fibrillation patients who are ineligible for long-term anticoagulation therapy.
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http://dx.doi.org/10.4244/DOI Listing
June 2010

2-year results of the AUTAX (Austrian Multivessel TAXUS-Stent) registry beyond the SYNTAX (synergy between percutaneous coronary intervention with TAXUS and cardiac surgery) study.

JACC Cardiovasc Interv 2009 Aug;2(8):718-27

Department of Cardiology, Medical University of Vienna, Vienna, Austria.

Objectives: The multicenter AUTAX (Austrian Multivessel TAXUS-Stent) registry investigated the 2-year clinical/angiographic outcomes of patients with multivessel coronary artery disease after implantation of TAXUS Express stents (Boston Scientific, Natick, Massachusetts), in a "real-world" setting.

Background: The AUTAX registry included patients with 2- or 3-vessel disease, with/without previous percutaneous coronary intervention (PCI) and concomitant surgery.

Methods: Patients (n = 441, 64 +/- 12 years, 78% men) (n = 1,080 lesions) with possible complete revascularization by PCI were prospectively included. Median clinical follow-up was 753 (quartiles 728 to 775) days after PCI in 95.7%, with control angiography of 78% at 6 months. The primary end point was the composite of major adverse cardiac (nonfatal acute myocardial infarction [AMI], all-cause mortality, target lesion revascularization [TLR]) and cerebrovascular events (MACCE). Potential risk factor effects on 2-year MACCE were evaluated using Cox regression.

Results: Complete revascularization was successful in 90.5%, with left main PCI of 6.8%. Rates of acute, subacute, and late stent thrombosis were 0.7%, 0.5%, and 0.5%. Two-year follow-up identified AMI (1.4%), death (3.6%), stroke (0.2%), and TLR (13.1%), for a composite MACCE of 18.3%. The binary restenosis rate was 10.8%. The median of cumulative SYNTAX score was 23.0 (range 12.0 to 56.5). The SYNTAX score did not predict TLR or MACCE, due to lack of scoring of restenotic or bypass stenoses (29.8%). Age (hazard ratio [HR]: 1.03, p = 0.019) and acute coronary syndrome (HR: 2.1, p = 0.001) were significant predictors of 2-year MACCE. Incomplete revascularization predicted death or AMI (HR: 3.84, p = 0.002).

Conclusions: With the aim of complete revascularization, TAXUS stent implantations can be safe for patients with multivessel disease. The AUTAX registry including patients with post-PCI lesions provides additional information to the SYNTAX (Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery) study. (Austrian Multivessel TAXUS-Stent Registry; NCT00738686).
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http://dx.doi.org/10.1016/j.jcin.2009.05.019DOI Listing
August 2009

Identification and characterization of novel recombinant vaccine antigens for immunization against genital Chlamydia trachomatis.

FEMS Immunol Med Microbiol 2009 Mar;55(2):258-70

Infectious Disease Research Institute, Seattle, WA 98104, USA.

Chlamydia trachomatis infection is the most common sexually transmitted bacterial infection worldwide, with over 91 million cases estimated annually. An effective subunit vaccine against Chlamydia may require a multivalent subunit cocktail of antigens in a single formulation for broad coverage of a heterogeneous major histocompatibility complex population. Herein, we describe the identification of novel C. trachomatis antigens by CD4+ and CD8+ T-cell expression cloning, serological expression cloning, and an in silico analysis of the C. trachomatis genome. These antigens elicited human CD4+ T-cell responses, and a subset proved to be immunogenic and protective when administered as immunoprophylactic vaccines against C. trachomatis challenge. Candidate vaccines consisting of the prioritized C. trachomatis antigens adjuvanted in a GlaxoSmithKline proprietary AS01B adjuvant were prioritized based on induction of solid protection against challenge in C57BL/6 and BALB/c mice with C. trachomatis. Some of the vaccines prevented bacterial shedding and colonization of the upper genital tract to varying degrees by mechanisms that may include CD4+ T cells.
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http://dx.doi.org/10.1111/j.1574-695X.2008.00527.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776724PMC
March 2009

Small vessel stenting with cobalt-chromium stents (Arthos Pico) in a real world setting.

Coron Artery Dis 2007 Jun;18(4):305-11

Department of Cardiology, Medical University of Vienna, Vienna, Austria.

Background: In current clinical practice, 35-67% of significant coronary artery lesions are located in small (<3.0 mm) vessels, a setting with poor short- and long-term results after percutaneous coronary interventions.

Objectives: The aim of the present Arthos Pico Austria Multicenter Registry is to demonstrate the safety and efficacy of the Arthos Pico (cobalt-chromium alloy) stent implantation in small coronary arteries in a real world setting.

Methods: Two hundred and three patients (mean age, 67+/-12 years; 63% male) were included in the Registry; 199 patients (98%) were controlled clinically (including noninvasive stress tests) 6 and 12 months after stent implantation. Clinically driven angiographic controls were performed in 37 patients (18.2%) at mean 6 months after stenting. The primary endpoint of the study was the 6-month rate of major adverse cardiac events (as target vessel revascularization, all cause death, and acute myocardial infarction), the secondary endpoints were the intervention complications, and the occurrence of acute and subacute stent thrombosis.

Results: The procedural success was 99%. The rates of acute and subacute stent thrombosis were 0.5 and 1.5%, respectively. During the 6-month clinical follow-up, primary endpoint events (major adverse cardiac events) were recorded in 13% of the clinically controlled patients: four patients (2%) with acute myocardial infarction; 12 patients (6%) with target vessel revascularization; and 10 patients died (5%), resulting in an event-free survival rate of 87%. Between the 6- and 12-month follow-up, additional target vessel revascularization was performed in three patients, acute myocardial infarction and death occurred in one patient each, respectively. Thus, the 12-month major adverse cardiac event-free survival rate was 85%. Patients who died had older age (76+/-7 years) and a high proportion of type C lesions (50%) at the initial angiography. Multivariate analysis revealed older age (P=0.026) and type C lesions (P=0.016) as significant predictors for all causes of death.

Conclusion: In conclusion, stenting of small arteries with Arthos Pico is safe and effective in the prevention of major adverse cardiac events during 6- and 12-month follow-up.
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http://dx.doi.org/10.1097/MCA.0b013e3281286541DOI Listing
June 2007

TLR4 agonists as immunomodulatory agents.

J Endotoxin Res 2006 ;12(5):313-9

GlaxoSmithKline Biologicals North America, Seattle, WA, USA.

Monophosphoryl lipid A (MPL) is a potent vaccine adjuvant derived from Salmonella minnesota that was recently licensed in Europe as a component of an improved vaccine for hepatitis B (Fendrix). MPL, like lipopolysaccharide from which it is derived, signals via the TLR4/MD-2 complex. We have produced a series of synthetic Toll-like receptor 4 (TLR4) agonists that are based upon the structure of the major hexa-acylated congener contained within MPL. These TLR4 agonists, termed the aminoalkyl glucosaminide phosphates (AGPs), stimulate the production of various cytokines by human peripheral blood mononuclear cells in vitro and up-regulate cell surface markers on monocytes, NK cells and B cells. In addition, AGPs provide non-specific resistance to challenge with viral and bacterial pathogens when administered to the upper airways of mice. Structure-activity relationship studies have shown that the activation of innate immune effectors by AGPs depends primarily on the length of the secondary acyl chains and the nature of the functional group attached to the aglycon component. Moreover, AGPs can act as potent adjuvants for mucosal administration of vaccine antigens, enhancing both antigen-specific antibody and cell-mediated immune responses. Thus, by combining the adjuvant and non-specific resistance induction properties of AGPs it may be possible to generate mucosal vaccines that provide innate protection immediately following administration together with long-term acquired immunity.
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http://dx.doi.org/10.1179/096805106X118753DOI Listing
December 2006

A synthetic TLR4 antagonist has anti-inflammatory effects in two murine models of inflammatory bowel disease.

J Immunol 2005 May;174(10):6416-23

Corixa Corporation, Seattle, WA 98101, USA.

Current evidence indicates that the chronic inflammation observed in the intestines of patients with inflammatory bowel disease is due to an aberrant immune response to enteric flora. We have developed a lipid A-mimetic, CRX-526, which has antagonistic activity for TLR4 and can block the interaction of LPS with the immune system. CRX-526 can prevent the expression of proinflammatory genes stimulated by LPS in vitro. This antagonist activity of CRX-526 is directly related to its structure, particularly secondary fatty acyl chain length. In vivo, CRX-526 treatment blocks the ability of LPS to induce TNF-alpha release. Importantly, treatment with CRX-526 inhibits the development of moderate-to-severe disease in two mouse models of colonic inflammation: the dextran sodium sulfate model and multidrug resistance gene 1a-deficient mice. By blocking the interaction between enteric bacteria and the innate immune system, CRX-526 may be an effective therapeutic molecule for inflammatory bowel disease.
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http://dx.doi.org/10.4049/jimmunol.174.10.6416DOI Listing
May 2005

Differential regulation of inflammatory cytokine secretion by human dendritic cells upon Chlamydia trachomatis infection.

Infect Immun 2004 Dec;72(12):7231-9

Corixa Corporation, 1900 9th Ave., Suite 1100, Seattle, WA 98101, USA.

Chlamydia trachomatis is an obligate intracellular gram-negative bacterium responsible for a wide spectrum of diseases in humans. Both genital and ocular C. trachomatis infections are associated with tissue inflammation and pathology. Dendritic cells (DC) play an important role in both innate and adaptive immune responses to microbial pathogens and are a source of inflammatory cytokines. To determine the potential contribution of DC to the inflammatory process, human DC were infected with C. trachomatis serovar E or L2. Both C. trachomatis serovars were found to infect and replicate in DC. Upon infection, DC up-regulated the expression of costimulatory (B7-1) and cell adhesion (ICAM-1) molecules. Furthermore, chlamydial infection induced the secretion of interleukin-1beta (IL-1beta), IL-6, IL-8, IL-12p70, IL-18, and tumor necrosis factor alpha (TNF-alpha). The mechanisms involved in Chlamydia-induced IL-1beta and IL-18 secretion differed from those of the other cytokines. Chlamydia-induced IL-1beta and IL-18 secretion required infection with viable bacteria and was associated with the Chlamydia-induced activation of caspase-1 in infected host cells. In contrast, TNF-alpha and IL-6 secretion did not require that the Chlamydia be viable, suggesting that there are at least two mechanisms involved in the Chlamydia-induced cytokine secretion in DC. Interestingly, an antibody to Toll-like receptor 4 inhibited Chlamydia-induced IL-1beta, IL-6, and TNF-alpha secretion. The data herein demonstrate that DC can be infected by human C. trachomatis serovars and that chlamydial components regulate the secretion of various cytokines in DC. Collectively, these data suggest that DC play a role in the inflammatory processes caused by chlamydial infections.
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http://dx.doi.org/10.1128/IAI.72.12.7231-7239.2004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC529152PMC
December 2004

Human CD8+ T cells recognize the 60-kDa cysteine-rich outer membrane protein from Chlamydia trachomatis.

J Immunol 2004 Dec;173(11):6905-13

Corixa, Seattle, WA 98101, USA.

The intracellular bacterial pathogen Chlamydia is sequestered from the host cell cytoplasm by remaining within an inclusion body during its replication cycle. Nevertheless, CD8(+) T cells recognizing Chlamydia Ags in the context of MHC class I molecules are primed during infection. We have recently described derivation of Chlamydia-specific human CD8(+) T cells by using infected dendritic cells as a surrogate system to reflect Chlamydia-specific CD8(+) T cell responses in vivo. These CD8(+) T cell clones recognize chlamydial Ags processed via the conventional class Ia processing pathway, as assessed by treatment of infected APC with lactacystin and brefeldin A, suggesting that the Ags are translocated from the chlamydial inclusion into the host cell cytosol. In this study, outer membrane protein 2 (OmcB) was identified as the Ag recognized by one of these Chlamydia-specific human CD8(+) T cells, and we defined the HLA*A0101-restricted epitope from this Ag. CD8(+) T cell responses to this epitope were present at high frequencies in the peripheral blood of both of two HLA*A0101 donors tested. In vitro chlamydial growth was completely inhibited by the OmcB-specific CD8(+) T cell clone independently of lytic mechanisms. OmcB is a 60-kDa protein that has been postulated to be associated with the Chlamydia outer membrane complex. The subcellular localization of OmcB to the cytosol of infected cells, as determined by conventional MHC class I Ag processing and presentation, suggests the possibility of an additional, cytosolic-associated function for this protein.
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http://dx.doi.org/10.4049/jimmunol.173.11.6905DOI Listing
December 2004

Short- and long-term clinical outcome after various stent implantation: overview of the results of uni- and multicenter stent registries.

Catheter Cardiovasc Interv 2004 Jul;62(3):331-8

Department of Cardiology, University of Vienna, Vienna, Austria.

The present study reports the results of the short- and long-term outcomes of prospective uni- and multicenter stent registries: Palmaz-Schatz (n = 140 patients), Ave-Micro and GFX (n = 280), Multilink Duet (n = 340), Multilink Tetra (n = 192), and Carbo (n = 140) Stent Registries, as well as the predictors and angiographic cutoff points predicting major adverse cardiac events (MACE) after different stent implantations. Significant decrease in subacute stent thrombosis (from 2.9% to 0) and MACE (from 35% to 8.3%) occurred as the improved stents, optimized stent implantation technique, and new postintervention drug therapy were introduced. The changes of angiographic cutoff values (postintervention minimal lumen diameter and preintervention reference diameter: from 2.9 and 3.1 mm for Palmaz-Schatz to 2.5 and 2.8 mm for Multilink Duet, Multilink Tetra, and Carbo stents) and clinical and angiographic factors predicting MACE indicated the change of traditional restenosis paradigm and that progress in clinical practice might be able to counterbalance unfavorable lesion and intervention-related characteristics.
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http://dx.doi.org/10.1002/ccd.20013DOI Listing
July 2004

Pre-existing anticardiolipin antibodies and development of restenosis after coronary balloon angioplasty: predictive value for a complicated course?

Blood Coagul Fibrinolysis 2004 Jun;15(4):311-6

Department of Internal Medicine II, Division of Cardiology, Medical University of Vienna, Wilhelminen-Hospital, Vienna, Austria.

Immune mechanisms play a critical role in cardiovascular disease. Cardiolipins are candidate autoantigens with a prothrombotic activity of their corresponding antibodies. We investigated the influence of pre-existing immunoglobulin (Ig)M and IgG anticardiolipin (aCL) antibodies on restenosis after coronary balloon angioplasty and their interaction with tissue plasminogen activator, plasminogen activator inhibitor type-1, von Willebrand factor and lipoprotein (a) in 132 patients with stable angina pectoris using immunoassays. Thirty percent of patients developed angiographically proven restenosis estimated by three independent experienced angiographers; 12% of all patients developed recurrent restenoses at the same site during a follow-up period of 2 years. Circulating IgM aCL antibodies categorized by quartiles predicted recurrent restenoses (logistic regression, for trend P < 0.04) with an increase of relative risk (RR) per quartile of 2.09. The predictive value of IgM aCL antibodies was unchanged adjusting for established cardiovascular risk factors (P = 0.028, RR = 2.69), extent of coronary artery disease (P = 0.014, RR = 2.73) and inflammatory parameters (P = 0.025, RR = 2.79), but lost significance adjusting for other prothrombotic parameters (P = 0.24, RR = 1.76). IgM aCL antibodies positively correlated with lipoprotein (a) (r = 0.23, P = 0.04). However, there was no significant interaction between their influences on recurrent restenoses. The other prothrombotic parameters did not predict single or recurrent restenoses. In conclusion, IgM aCL antibodies may help to identify a group of patients at high risk for recurrent restenoses after coronary balloon angioplasty.
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http://dx.doi.org/10.1097/00001721-200406000-00004DOI Listing
June 2004

Predictors of early reangiography within 30 days after coronary stenting.

Can J Cardiol 2003 Dec;19(13):1503-8

Department of Cardiology, University of Vienna Medical School, Vienna, Austria.

Background: A substantial number of early urgent reangiographies after coronary stenting do not reveal coronary abnormalities such as thrombosis, dissection, restenosis or side branch occlusion. The characterization of patients undergoing early reangiography may reduce the number of potentially unnecessary procedures.

Objective: To evaluate the predictors for unplanned early re- angiography on the basis of the information available at the time of stent implantation.

Methods: All 71 patients with reangiography after stent implantation between 1994 and 1998 in the Department of Cardiology at the University Hospital of Vienna, Austria, were compared with a control sample of 88 patients without early reangiography during the same period (control subjects were matched for the time point of the first intervention). The clinical and procedural variables were analyzed in this case-control study. For specification of the group with negative reangiograms, differences in clinical parameters between patients with negative versus patients with positive reangiograms were also analyzed.

Results: Clinical predictors for early reangiography of patients without evidence of important coronary pathology were a history of hypertension and left ventricular hypertrophy, as well as total cholesterol. The angiographic predictor was multiple vessel disease, and procedural risk factors included the left anterior descending artery as the target artery, type B and C lesions and total occlusion in the left anterior descending artery, as well as high-pressure balloon stent deployment.

Conclusion: Clinical, angiographic and procedural variables predict the risk for unplanned early reangiography after coronary stenting. Hypertensive heart disease may mimic acute coronary events; hypertension and left ventricular hypertrophy represent independent predictors of unplanned reangiography in patients with good short-term results.
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December 2003

Structure-activity relationship of synthetic toll-like receptor 4 agonists.

J Biol Chem 2004 Feb 21;279(6):4440-9. Epub 2003 Oct 21.

Corixa Corporation, Seattle, Washington 98104, USA.

Important questions remain regarding the impact of variations in the structure of the lipid A portion of lipopolysaccharide on activation of cells via the Toll-like receptor 4 complex. We have studied a series of synthetic lipid A mimetic compounds known as aminoalkyl glucosaminide phosphates in which the length of the secondary acyl chain has been systematically varied. Using transcriptional profiling of human monocytes and responses of Toll-like receptor 4 complex cell transfectants, we demonstrate a clear dependence of length on secondary acyl chain on Toll-like receptor 4 activation. Compounds with secondary acyl chains less than eight carbons in length have dramatically reduced activity, and substitutions of the left-sided secondary acyl chain had the most important effect on the Toll-like receptor 4 agonist activity of these molecules. The structure-function relationships of these compounds assessed via the induction of chemokines and cytokines following in vivo administration closely mirrored those seen with cell-based studies. This novel set of synthetic lipid A mimetics will be useful for Toll-like receptor 4-based investigations and may have clinical utility as stand-alone immunomodulators.
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http://dx.doi.org/10.1074/jbc.M310760200DOI Listing
February 2004

A randomized trial of polytetrafluoroethylene-membrane-covered stents compared with conventional stents in aortocoronary saphenous vein grafts.

J Am Coll Cardiol 2003 Oct;42(8):1360-9

J W Goethe Universität, Frankfurt/Main, Germany.

We compared a conventional stent (Jostent Flex, Jomed GmbH, Rangendingen, Germany) with a polytetrafluoroethylene (PTFE)-membrane-covered stent (Jostent Stentgraft) in patients undergoing intervention of a stenosis in an obstructed vein graft. The use of stents improved results of percutaneous revascularization of obstructed vein grafts, but did not demonstrate the reduced elevated restenosis rate. In addition, long-term clinical event rate is still high compared with intervention in native vessels. Observational studies suggested that stents covered with a PTFE membrane might be associated with a low complication and restenosis rate in venous bypass grafts. This prospective multicenter study included a total of 211 patients who were randomly assigned to receive either a Flex stent or Stentgraft. The primary end point was binary restenosis rate at six months by core lab quantitative coronary angiography. Acute success and procedural events were comparable between the two groups. Restenosis rate was not significantly different between the Flex (20%) and the Stentgraft (29%) groups (p = 0.15), although there was a nonsignificant trend toward a higher late occlusion rate in the Stentgraft group (7% vs. 16%, p = 0.069) at follow-up. Likewise, after a mean observation period of 14 months, cumulative event rates (death, myocardial infarction, or target lesion revascularization) were comparable in the two groups (31% vs. 31%, p = 0.93). This controlled trial does not indicate a superiority of the PTFE-membrane-covered Stentgraft compared with a conventional stent with respect to acute results, restenosis, or clinical event rates.
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http://dx.doi.org/10.1016/s0735-1097(03)01038-6DOI Listing
October 2003

Functional characterization of class Ia- and non-class Ia-restricted Chlamydia-reactive CD8+ T cell responses in humans.

J Immunol 2003 Oct;171(8):4278-86

Corixa Corporation, Seattle, WA 98104, USA.

CD8(+) T cells are a key immune component for the eradication of many intracellular pathogens. This study aims to characterize the human CD8(+) T cell response to naturally processed chlamydial Ags in individuals exposed to the intracellular pathogen Chlamydia trachomatis. By using C. trachomatis-infected autologous dendritic cells (DCs) as stimulators, Chlamydia-reactive CD8(+) T cell responses were detected in all 10 individuals tested. The majority of the Chlamydia-reactive CD8(+) T cells were non-MHC class Ia restricted in all three of the individuals tested. From one donor, three non-class Ia-restricted and two class Ia-restricted Chlamydia-specific CD8(+) T cells were cloned and characterized further. All five T cell clones secreted IFN-gamma in response to autologous DCs infected with viable Chlamydia, but not with DCs pulsed with inactivated chlamydial elementary bodies. MHC class Ia-restricted and non-class Ia-restricted responses were inhibited by DC treatment with a proteasomal inhibitor and an endoplasmic reticulum-Golgi transport inhibitor, suggesting that these T cells recognize a peptide Ag translocated to the host cell cytosol during infection that is processed via the classical class Ia Ag-processing pathway. Even though both restricted and nonrestricted CD8(+) T cells produced IFN-gamma in response to Chlamydia-infected fibroblasts, only the non-class Ia-restricted cells were lytic for these targets. The class Ia-restricted CTLs, however, were capable of cytolysis as measured by redirected killing. Collectively, these data demonstrate that both class Ia-restricted and non-classically restricted CD8(+) T cells are elicited in C. trachomatis-exposed individuals. Their role in host immunity remains to be elucidated.
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http://dx.doi.org/10.4049/jimmunol.171.8.4278DOI Listing
October 2003

Parameters of the tissue factor pathway with coumadin/dipyridamole versus ticlopidine as adjunct antithrombotic-drug regimen in coronary artery stenting.

Blood Coagul Fibrinolysis 2003 Jun;14(4):379-86

Division of Angiology, 2nd Department of Medicine, General Hospital, AKH, University of Vienna, Austria.

A different rate and timing of subacute stent thrombosis after percutaneous coronary intervention was reported with various peri-interventional antithrombotic regimens. Next to platelet activation, coagulation triggered by tissue factor (TF) may play a key role in this process. Thirty-one consecutive patients with stable and unstable angina undergoing coronary stenting were randomly assigned to adjunct oral anticoagulation/anti-platelet therapy (coumadin, dipyridamole, aspirin and heparin; n = 16) or adjunct anti-platelet therapy with thienopyridin (ticlopidine, aspirin and heparin; n = 15). Antigen levels of plasma TF, total tissue factor pathway inhibitor (TFPI) and TFPI/ activated factor X (TFPI/FXa) complex were determined before and for up to 6 days after intervention by immunoassay. At baseline, significantly higher levels of plasma TF and TFPI/FXa were found in patients with unstable angina [TF, 161 pg/ml (126-191 pg/ml); TFPI/FXa, 7.8 ng/ml (6.1-9.6 ng/ml)] compared with stable angina [TF, 62 pg/ml (46-82 pg/ml), P < 0.0001; TFPI/FXa, 4.5 ng/ml (3-7.6 ng/ml), P= 0.003]. One hour after intervention, an increase of plasma TF and TFPI/FXa was seen in both treatment groups. In unstable angina patients, plasma levels of TF, TFPI and TFPI/FXa were more efficiently reduced by adjunct ticlopidine therapy compared with adjunct coumadin/dipyridamole. These data suggest reduced release of circulating TF by combined anti-platelet therapy with ticlopidine and aspirin after coronary artery stenting, which may-contribute to the lower incidence of subacute stent thrombosis previously observed.
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http://dx.doi.org/10.1097/00001721-200306000-00009DOI Listing
June 2003

Coronary no-reflow is caused by shedding of active tissue factor from dissected atherosclerotic plaque.

Blood 2002 Apr;99(8):2794-800

Department of Cardiology, University of Vienna, Austria.

Defined angiographically, no-reflow (NR) manifests as an acute reduction in coronary flow in the absence of epicardial vessel obstruction. One candidate protein to cause coronary NR is tissue factor (TF), which is abundant in atherosclerotic plaque and a cofactor for activated plasma coagulation factor VII. Scrapings from atherosclerotic carotid arteries contained TF activity (corresponding to 33.03 +/- 13.00 pg/cm(2) luminal plaque surface). Active TF was sedimented, indicating that TF was associated with membranes. Coronary blood was drawn from 6 patients undergoing coronary interventions with the distal protection device PercuSurge GuardWire (Traatek, Miami, FL). Fine particulate material that was recovered from coronary blood showed TF activity (corresponding to 91.1 +/- 62.16 pg/mL authentic TF). To examine the role of TF in acute coronary NR, blood was drawn via a catheter from coronary vessels in 13 patients during NR and after restoration of flow. Mean TF antigen levels were elevated during NR (194.3 +/- 142.8 pg/mL) as compared with levels after flow restoration (73.27 +/- 31.90 pg/mL; P =.02). To dissect the effects of particulate material and purified TF on flow, selective intracoronary injection of atherosclerotic material or purified relipidated TF was performed in a porcine model. TF induced NR in the model, thus strengthening the concept that TF is causal, not just a bystander to atherosclerotic plaque material. The data suggest that active TF is released from dissected coronary atherosclerotic plaque and is one of the factors causing the NR phenomenon. Thus, blood-borne TF in the coronary circulation is a major determinant of flow.
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http://dx.doi.org/10.1182/blood.v99.8.2794DOI Listing
April 2002