Abstract: CD14, a pattern recognition receptor found on myeloid cells, is a critical component of the innate immune system that mediates local and systemic host responses to Gram-negative and Gram-positive bacterial products. Previous studies in normal animals have tested the effect of CD14 blockade on the systemic response to i.v. LPS. The goals of the study were to determine whether CD14 blockade protected against the deleterious systemic response associated with Escherichia coli pneumonia and to determine whether this strategy affected the pulmonary response to tissue infection. Rabbits were pretreated with either anti-CD14 mAb or isotype control mAb at 2.5 mg/kg. E. coli (1 x 109 CFU) was inoculated into the lungs, and the animals were observed for either 4 or 24 h. The blockade of CD14 improved the mean arterial blood pressure (p = 0.001) and decreased the i.v. fluid requirements (p = 0.01). Although this therapy protected the vascular compartment, rabbits treated with anti-CD14 mAb had increased bacterial burdens in the bronchoalveolar lavage fluid recovered from the instilled lung (p = 0.005) and widened alveolar-arterial oxygen difference. Blockade of CD14 prevents the deleterious systemic responses that occur in sepsis; however, other measures are necessary to control bacterial proliferation at the primary site of infection.

Abstract: Background. The CD40-CD154 receptor-ligand pair plays a critical role in allograft rejection by mediating the activation of endothelial cells, antigen-presenting cells, and T cells. Blockade of this interaction prevents acute allograft rejection and leads to prolonged allograft survival in numerous experimental models, but in most cases indefinite graft survival is not achieved due to evolving transplant arteriosclerosis. In this study, we have used a model of transplant arteriosclerosis to investigate whether CD4 + and CD8 + T cells are differentially affected by CD154 blockade. Methods. BALB/c (H2 d ) aortic grafts were transplanted into C57BL/6 (H2 b ) recipients treated with anti-CD154 monoclonal antibody in the presence or absence of CD8 + T-cell depletion. Histology and morphometric measurements were performed on day 30 after transplantation. Results. Only combined treatment with anti-CD154 and anti-CD8 monoclonal antibodies resulted in a significant reduction of intimal proliferation (33±10% vs. 67±14%; untreated control). Administration of either antibody alone did not produce this effect. Thymectomy did not alter the degree of intimal proliferation observed in any of the treatment groups. Conclusions. Our data provide direct evidence that CD8 + T cells are not targeted effectively by CD154 blockade and that the transplant arteriosclerosis seen after CD154 blockade is not due to recent thymic emigrant T cells.

Abstract: Background—The relative efficacy of endothelin-A (ETA) receptor blockade versus combined ETA-ETB receptor blockade in chronic heart failure (CHF) is still largely unknown. Methods and Results—We compared, in a rat model of CHF (coronary ligation), the hemodynamic and structural effects of 1 month of treatment with the ETA antagonist ABT-627 (5 mg · kg−1 · d−1), the ETB antagonist A-192621 (30 mg · kg−1 · d−1) or a combination of the 2 drugs. Doses were chosen for their capacity to block the pressor response to ET-1 (for ETA blockade) or the depressor responses to sarafotoxin S6c or ET-1 (for ETB blockade). ETA and combined ETA-ETB blockade reduced systolic blood pressure to the same extent, whereas ETB blockade had no effect. In contrast, only combined ETA-ETB blockade significantly reduced heart rate. Both ETA and combined ETA-ETB blockade, but not ETB blockade alone, increased left ventricular (LV) fractional shortening and wall thickening and reduced LV end-diastolic pressure, as well as LV end-diastol...

Abstract: Study Design. Nerve root stimulation thresholds were studied relative to the level of neuromuscular blockade in patients undergoing lumbar decompression surgery. Objectives. To determine what levels of intraoperative neuromuscular blockade can be used during pedicle screw stimulation. Background Data. Previous studies of intraoperative pedicle screw stimulation thresholds have failed to determine the effect of neuromuscular blockade on the stimulation threshold. Methods. Twenty-one roots in 10 patients undergoing lumbar decompression surgery were studied at different levels of neuromuscular blockade. Ninety-five nerve root thresholds were determined relative to level of blockade. Results. Neuromuscular blockade below 80% provides nerve root thresholds similar to thresholds without blockade. Conclusions. Neuromuscular blockade should be less than 80% when using pedicle screw electrical stimulation testing.

Abstract: It has been reported that costimulation blockade can result in T cell anergy. We investigated the effects of blocking costimulatory molecules in vivo on the development of experimental autoimmune uveoretinitis (EAU), a model for autoimmune uveitis in humans that is induced in mice by immunization with the retinal Ag interphotoreceptor retinoid binding protein. B10.A mice immunized with a uveitogenic regimen of interphotoreceptor retinoid-binding protein were treated with Abs to B7.1 and B7.2 for 2 wk. Evaluation of EAU and immunological responses 1 wk later showed that disease had been abrogated, and cellular responses were suppressed. To determine whether the costimulation blockade resulted in tolerance, adult-thymectomized mice immunized for uveitis and treated with anti-B7 or anti-CD28 were rechallenged for uveitis induction 5 wk after the initial immunization. Although confirmed to be disease free after the initial immunization, both anti-B7- and anti-CD28-treated mice developed severe EAU and elevated cellular responses after the rechallenge, equivalent to those of control mice. We conclude that in this model costimulatory blockade in vivo prevents the development of autoimmune disease, but does not result in long-term tolerance. The data are compatible with the interpretation that B7/CD28 blockade prevents generation of effector, but not of memory, T cells.

Abstract: Blockade or gene deletion of inducible nitric oxide synthase (iNOS) fails to fully abrogate all the sequelae leading to the high morbidity of septicemia. An increase in substrate uptake may be nece...

Abstract: Converting-enzyme inhibition reduces cardiovascular hypertrophy in hypertensive subjects. Whether the blockade of angiotensin II type 1 (AT1) receptors reduces arterial hypertrophy has neve

Abstract: We have examined observational data from four published studies investigating the incidence of postoperative silent myocardial ischaemia (post-SMI) for the effects of chronic intercurrent therapy with beta-adrenoceptor blockade or chronic calcium channel entry blockade. A total of 453 patients underwent ambulatory ECG monitoring before and for 2 days after non-cardiac surgery; 79 patients were receiving chronic intercurrent beta-adrenoceptor blockade and 70 calcium channel entry blockade for ischaemic heart disease or arterial hypertension. Using logistic regression analysis, we defined a model for post-SMI that included four significant terms: beta-adrenoceptor blockade; calcium channel entry blockade; arterial hypertension; and vascular surgery. Using univariate regression, there was no effect of chronic beta-adrenoceptor blocking therapy on post-SMI (odds ratio 0.94 (95% confidence intervals 0.54-1.65)), but there was a higher incidence of post-SMI in patients receiving chronic calcium channel entry blocking drugs (odds ratio 1.95 (1.15-3.32); P = 0.015). There was no interaction between beta-adrenoceptor blockade and calcium channel entry blockade for postoperative SMI (odds ratio 2.48 (0.71-8.73)), but there was an interaction between beta-adrenoceptor blockade, calcium channel entry blockade, hypertension and vascular surgery (P = 0.0201). These findings are at variance with those which have shown effects of preoperative beta-adrenoceptor blockade on the incidence of post-SMI over the first 7 days after operation, and on mortality rates to 2 yr. There are no comparable data examining the effects of chronic intercurrent calcium channel entry blockade.

Abstract: CTLA-4 (CD152) is thought to be a negative regulator of T cell activation. Little is known about the function of CTLA-4 in Th2-type immune responses. We have investigated the effect of initial treatment with anti-CTLA-4 mAb on murine chronic graft-vs-host disease. Transfer of parental BALB/c splenocytes into C57BL/6 × BALB/c F1 mice induced serum IgE production, IL-4 expression by donor CD4+ T cells, and host allo-Ag-specific IgG1 production at 6–9 wk after transfer. Treatment with anti-CTLA-4 mAb for the initial 2 wk significantly reduced IgE and IgG1 production and IL-4 expression. Analysis of the splenic phenotype revealed the enhancement of donor T cell expansion, especially within the CD8 subset, and the elimination of host cells early after anti-CTLA-4 mAb treatment. This treatment did not affect early IFN-γ expression by CD4+ and CD8+ T cells and anti-host cytolytic activity. Thus, blockade of CTLA-4 greatly enhanced CD8+ T cell expansion, and this may result in the regulation of consequent Th2-mediated humoral immune responses. These findings suggest a new approach for regulating IgE-mediated allergic immune responses by blockade of CTLA-4 during a critical period of Ag sensitization.

Abstract: Interleukin-10 (IL-10) is associated with inhibition of cell-mediated immunity and downregulation of the expression of costimulatory molecules required for T-cell activation. When IL-10-deficient (IL-10KO) mice are infected with Toxoplasma gondii, they succumb to a T-cell-mediated shock-like reaction characterized by the overproduction of IL-12 and gamma interferon (IFN-γ) associated with widespread necrosis of the liver. Since costimulation is critical for T-cell activation, we investigated the role of the CD28-B7 and CD40-CD40 ligand (CD40L) interactions in this infection-induced immunopathology. Our studies show that infection of mice with T. gondii resulted in increased expression of B7 and CD40 that was similar in wild-type and IL-10KO mice. In vivo blockade of the CD28-B7 or CD40-CD40L interactions following infection of IL-10KO mice with T. gondii did not affect serum levels of IFN-γ or IL-12, nor did it prevent death in these mice. However, when both pathways were blocked, the IL-10KO mice survived the acute phase of infection and had reduced serum levels of IFN-γ and alanine transaminase as well as decreased expression of inducible nitric oxide synthase in the liver and spleen. Analysis of parasite-specific recall responses from infected IL-10KO mice revealed that blockade of the CD40-CD40L interaction had minimal effects on cytokine production, whereas blockade of the CD28-B7 interaction resulted in decreased production of IFN-γ but not IL-12. Further reduction of IFN-γ production was observed when both costimulatory pathways were blocked. Together, these results demonstrate that the CD28-B7 and CD40-CD40L interactions are involved in the development of infection-induced immunopathology in the absence of IL-10.

Abstract: Background—The goal of this study was to determine the comparative effects of angiotensin II type 1 (AT1) receptor inhibition alone, endothelin-1 (ET) receptor blockade alone, and combined receptor blockade on left ventricular (LV) function, contractility, and neurohormonal system activity in a model of congestive heart failure (CHF). Methods and Results—Pigs were randomly assigned to each of 5 groups: (1) rapid atrial pacing (240 bpm) for 3 weeks (n=9), (2) concomitant AT1 receptor blockade (valsartan, 3 mg/kg per day) and rapid pacing (n=8), (3) concomitant ET receptor blockade (bosentan, 50 mg/kg BID) and rapid pacing (n=8), (4) concomitant combined AT1 and ET receptor inhibition and rapid pacing (n=8), and (5) sham-operated control (n=9). LV stroke volume was reduced from the control value after rapid pacing, was unchanged with either AT1 or ET receptor blockade alone, but was improved with combination treatment. LV peak wall stress was reduced in both groups with ET receptor blockade compared with th...

Abstract: Alpha-adrenergic receptor blockade by phentolamine increases the efficacy of vasodilators in penile corpus cavernosum

Abstract: Tasosartan is a long-acting angiotensin II (AngII) receptor blocker. Its long duration of action has been attributed to its active metabolite enoltasosartan. In this study we evaluated the relative contribution of tasosartan and enoltasosartan to the overall pharmacological effect of tasosartan. AngII receptor blockade effect of single doses of tasosartan (100 mg p.o. and 50 mg i.v) and enoltasosartan (2.5 mg i.v.) were compared in 12 healthy subjects in a randomized, double blind, three-period crossover study using two approaches: the in vivo blood pressure response to exogenous AngII and an ex vivo AngII radioreceptor assay. Tasosartan induced a rapid and sustained blockade of AngII subtype-1 (AT1) receptors. In vivo, tasosartan (p.o. or i.v.) blocked by 80% AT1 receptors 1 to 2 h after drug administration and still had a 40% effect at 32 h. In vitro, the blockade was estimated to be 90% at 2 h and 20% at 32 h. In contrast, the blockade induced by enoltasosartan was markedly delayed and hardly reached 60 to 70% despite the i.v. administration and high plasma levels. In vitro, the AT1 antagonistic effect of enoltasosartan was markedly influenced by the presence of plasma proteins, leading to a decrease in its affinity for the receptor and a slower receptor association rate. The early effect of tasosartan is due mainly to tasosartan itself with little if any contribution of enoltasosartan. The antagonistic effect of enoltasosartan appears later. The delayed in vivo blockade effect observed for enoltasosartan appears to be due to a high and tight protein binding and a slow dissociation process from the carrier.

Abstract: Objective. To investigate the longterm consequences of tumor necrosis factor-α (TNF-α) blockade in patients with rheumatoid arthritis (RA), to compare changes after repeated infusion of cA2 monoclonal antibody with those occurring after the initial treatment, and to investigate significant correlations of cellular or serological changes to the duration of clinical benefit for each patient. Methods. A clinical trial testing TNF-α monoclonal antibody cA2 in treatment of RA showed this therapeutic agent is highly effective. A dosage of I mg/kg or 10 mg/kg cA2, given in a single infusion, was compared to placebo. After clinical relapse all patients were (re)treated with 3 or 10 mg/kg cA2. In parallel to this clinical study, we investigated cellular and molecular changes induced by in vivo blockade of TNF-α. Results. After an initial transient increase, T lymphocyte counts were not significantly different from starting values throughout the observation period. Monocyte counts as well as serum interleukin 6 (IL-6) and soluble intercellular adhesion molecule 1 (sICAM-1) concentrations remained decreased for several weeks after infusion. After a repeated infusion, increases in numbers of T cells and decreases in monocytes and IL-6 and sICAM- concentrations were evident again. Changes in cell counts, however, were smaller, especially in the group initially treated with the low dose ( 1 mg/kg). despite a higher retreatment dosage of 3 or 10 mg/kg cA2. Similarly, in this group decrease of IL-6 and sICAM- 1 concentrations was less pronounced, was delayed to Day 7 after infusion, and lasted for a shorter period than seen after initial treatment. Conclusion. We conclude that in vivo TNF-α blockade leads to prolonged cellular and serological changes. This effect appears to be less pronounced after repeated infusion of cA2 compared to the initial treatment, mainly in the low dose group.

Abstract: Previous research has suggested a possible link between the effects of scopolamine-induced muscarinic cholinergic receptor blockade on memory and its effect on auditory P3 amplitude and la...

Abstract: Dharnidharka and colleagues raise an important point. Co-stimulation blockade using anti-CD154 and CTLA4-Ig, albeit remarkably effective in many models, has not proven universally successful in producing permanent engraftment in allograft models. Although the cited work of Larsen and Pearson4 showed universal survival of skin allografts for 50 days, after further observation, only 50% of the recipients in that study experienced permanent engraftment (C. Larsen, personal communication). In skin graft models, subtle differences in the precise source of the skin graft, the source of CTLA4-Ig and differences in the C3H/He substrains are potentially very important in determining outcome. In fact, Larsen and Pearson have just shown in another strain combination that asialo GM1+ CD8+ T cells are essential in co-stimulation blockade-resistant mouse skin allograft rejection7. Several other groups have noted that CD8+ T cells are responsible for co-stimulation blockade resistant rejection in intestinal8 and skin9 allograft models. And our own unpublished observations show that co-stimulation blockade is ineffective in blocking islet allograft rejection in a CD8+ T-cell receptor transgenic model. We know of several other groups that have noted CD8+ T-cell-dependent, co-stimulation blockade resistant allograft rejection. Recall that the expression of the co-stimulatory proteins differs from CD4+ to CD8+ T cells.