Modulation of neutrophil migration and superoxide anion release by metoprolol

The Potential Role of Angiotensin-Converting Enzyme Inhibitors and Beta-Blockers in Reducing Pneumonia Severity in Older Adults

Background Understanding the impact of pharmacological therapy on pneumonia severity is crucial for effective clinical management. The impact of angiotensin-converting enzyme inhibitors (ACEis) and beta-blockers (BBs) on pneumonia severity remains unknown, warranting further investigation. Methodology This retrospective study examined the hospital records of inpatients (≥75 years) admitted with community-acquired pneumonia in 2021. Pneumonia severity associated with the use of pre-established ACEi and BB therapy was documented using CURB-65 (confusion, uraemia, respiratory rate, blood pressure, age ≥65 years) and pneumonia severity index (PSI) scores. Descriptive statistics and multivariable linear regression were used to analyse differences across BB therapy, ACEi therapy, their combination, or neither (control group). Results A total of 803 patient records were examined, of whom 382 (47.6%) were male and 421 (52.4%) were female. Sample sizes for each group were as follows: control (n = 492), BB only (n = 185), ACEi only (n = 68), and BB + ACEi (n = 58). Distribution of aspiration pneumonia (AP) versus non-AP for each group, respectively, was control (21.1% vs. 78.9%), BB only (9.7% vs. 90.3%), ACEi only (7.3% vs. 92.7%), and ACEi + BB (12.1% vs. 87.9%). No significant differences in PSI and CURB-65 scores were found between intervention groups even after controlling for patient characteristics and irrespective of AP or non-AP aetiology. Patients with AP had significantly higher CURB-65 (p = 0.026) and PSI scores (p = 0.044) compared to those with non-AP. Conclusions Pre-prescribed ACEi or BB therapy did not appear to be associated with differences in pneumonia severity. There were no differences in pneumonia severity scores with ACEi and BB monotherapy or combined ACEi and BB therapy.

Efficacy and Safety of Bisoprolol in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis

Purpose

To evaluate the clinical efficacy and safety of bisoprolol in patients with chronic obstructive pulmonary disease (COPD).

Research Methods

This systematic review and meta-analysis was conducted following the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statements. The primary outcome measures analyzed included: Pulmonary function(FEV1, FEV1%, FVC), 6-minute walking distance (6MWD), adverse events and inflammatory cytokines(IL-6, IL-8, CRP).

Results

Thirty-five studies were included with a total of 3269 study participants, including 1650 in the bisoprolol group and 1619 in the control group. The effect of bisoprolol on lung function in patients with COPD, FEV1, MD (0.46 [95% CI, 0.27 to 0.65], P=0.000), FEV1%, MD (-0.64 [95% CI, 0.42 to 0.86], P=0.000), FVC, MD (0.20 [95% CI, 0.05 to 0.34], P=0.008), the results all showed a statistically significant result. The effect of bisoprolol on 6MWD in COPD patients, MD (1.37 [95% CI, 1.08 to 1.66], P=0.000), which showed a statistically significant result. The occurrence of adverse events in COPD patients treated with bisoprolol, RR (0.83 [95% CI, 0.54 to 1.26], P=0.382), resulted in no statistical significance. The effect of bisoprolol on inflammatory cytokines in COPD patients, IL-6, MD (-1.16 [95% CI, -1.67 to -0.65], P=0.000), IL-8, MD (-0.94 [95% CI, -1.32 to -0.56], P=0.000), CRP, MD (-1.74 [95% CI, -2.40 to -1.09], P=0.000), the results were statistically significant. We performed a subgroup analysis of each outcome indicator according to whether the patients had heart failure or not, and the results showed that the therapeutic effect of bisoprolol on COPD did not change with the presence or absence of heart failure.

Conclusion

Bisoprolol is safe and effective in the treatment of COPD, improving lung function and exercise performance in patients with COPD, and also reducing inflammatory markers in patients with COPD, and this effect is independent of the presence or absence of heart failure.

Regulation of Adrenergic, Serotonin, and Dopamine Receptors to Inhibit Diabetic Retinopathy: Monotherapies versus Combination Therapies

We compared monotherapies and combinations of therapies that regulate G-protein-coupled receptors (GPCRs) with respect to their abilities to inhibit early stages of diabetic retinopathy (DR) in streptozotocin-diabetic mice. Metoprolol (MTP; 0.04-1.0 mg/kg b.wt./day), bromocriptine (BRM; 0.01-0.1 mg/kg b.wt./day), doxazosin (DOX; 0.01-1.0 mg/kg b.wt./day), or tamsulosin (TAM; 0.05-0.25 mg/kg b.wt./day) were injected individually daily for 2 months in dose-response studies to assess their effects on the diabetes-induced increases in retinal superoxide and leukocyte-mediated cytotoxicity against vascular endothelial cells, both of which abnormalities have been implicated in the development of DR. Each of the individual drugs inhibited the diabetes-induced increase in retinal superoxide at the higher concentrations tested, but the inhibition was lost at lower doses. To determine whether combination therapies had superior effects over individual drugs, we intentionally selected for each drug a low dose that had little or no effect on the diabetes-induced retinal superoxide for use separately or in combinations in 8-month studies of retinal function, vascular permeability, and capillary degeneration in diabetes. At the low doses used, combinations of the drugs generally were more effective than individual drugs, but the low-dose MTP alone totally inhibited diabetes-induced reduction in a vision task, BRM or DOX alone totally inhibited the vascular permeability defect, and DOX alone totally inhibited diabetes-induced degeneration of retinal capillaries. Although low-dose MTP, BRM, DOX, or TAM individually had beneficial effects on some endpoints, combination of the therapies better inhibited the spectrum of DR lesions evaluated. SIGNIFICANCE STATEMENT: The pathogenesis of early stages of diabetic retinopathy remains incompletely understood, but multiple different cell types are believed to be involved in the pathogenic process. We have compared the effects of monotherapies to those of combinations of drugs that regulate GPCR signaling pathways with respect to their relative abilities to inhibit the development of early diabetic retinopathy.

Effect of β-blockers on the risk of COPD exacerbations according to indication of use: the Rotterdam Study

Observational studies report a reduction of COPD exacerbations in patients treated with β-blockers. In contrast, the Beta-Blockers for the Prevention of Acute Exacerbations of Chronic Obstructive Pulmonary Disease (BLOCK COPD) randomised controlled trial which excluded COPD patients with cardiovascular conditions showed an increase in COPD exacerbations. It is unclear whether this discrepancy could be explained by underlying cardiovascular comorbidity. We examined whether the association between use of β-blockers and risk of COPD exacerbations differed between patients with and without a cardiovascular indication for β-blockers use.

Within the Rotterdam Study, we followed COPD subjects until the first COPD exacerbation, or end of follow-up. Cardiovascular indication for β-blockers use was defined as a history of hypertension, coronary heart disease, atrial fibrillation and/or heart failure at baseline. The association between β-blockers use and COPD exacerbations was assessed using Cox proportional hazards models adjusted for age, sex, smoking, incident cardiovascular disease (i.e. heart failure, hypertension, atrial fibrillation and/or coronary heart disease during follow-up), respiratory drugs and nitrates.

In total, 1312 COPD patients with a mean age of 69.7±9.2 years were included. In patients with a cardiovascular indication (n=755, mean age of 70.4±8.8 years), current use of cardioselective β-blockers was significantly associated with a reduced risk of COPD exacerbations (HR 0.69, 95% CI 0.57–0.85). In contrast, in subjects without a cardiovascular indication (n=557, mean age of 68.8±9.7 years), current use of cardioselective β-blockers was not associated with an altered risk of COPD exacerbations (HR 0.94, 95% CI 0.55–1.62).

Use of cardioselective β-blockers reduced the risk of exacerbations in COPD patients with concomitant cardiovascular disease. Therefore, the potential benefits of β-blockers might be confined to COPD patients with cardiovascular disease.

Use of cardioselective β-blockers reduces the risk of COPD exacerbations in patients with concomitant cardiovascular disease. The potential benefits of β-blockers might be restricted to COPD patients with cardiovascular disease.https://bit.ly/3bB1RGg

Metoprolol exerts a non-class effect against ischaemia-reperfusion injury by abrogating exacerbated inflammation

Aims

Clinical guidelines recommend early intravenous β-blockers during ongoing myocardial infarction; however, it is unknown whether all β-blockers exert a similar cardioprotective effect. We experimentally compared three clinically approved intravenous β-blockers.

Methods and results

Mice undergoing 45 min/24 h ischaemia–reperfusion (I/R) received vehicle, metoprolol, atenolol, or propranolol at min 35. The effect on neutrophil infiltration was tested in three models of exacerbated inflammation. Neutrophil migration was evaluated in vitro and in vivo by intravital microscopy. The effect of β-blockers on the conformation of the β1 adrenergic receptor was studied in silico. Of the tested β-blockers, only metoprolol ameliorated I/R injury [infarct size (IS) = 18.0% ± 0.03% for metoprolol vs. 35.9% ± 0.03% for vehicle; P < 0.01]. Atenolol and propranolol had no effect on IS. In the three exacerbated inflammation models, neutrophil infiltration was significantly attenuated only in the presence of metoprolol (60%, 50%, and 70% reductions vs. vehicle in myocardial I/R injury, thioglycolate-induced peritonitis, and lipopolysaccharide-induced acute lung injury, respectively). Migration studies confirmed the particular ability of metoprolol to disrupt neutrophil dynamics. In silico analysis indicated different intracellular β1 adrenergic receptor conformational changes when bound to metoprolol than to the other two β-blockers.

Conclusions

Metoprolol exerts a disruptive action on neutrophil dynamics during exacerbated inflammation, resulting in an infarct-limiting effect not observed with atenolol or propranolol. The differential effect of β-blockers may be related to distinct conformational changes in the β1 adrenergic receptor upon metoprolol binding. If these data are confirmed in a clinical trial, metoprolol should become the intravenous β-blocker of choice for patients with ongoing infarction.

Association of β-blocker use with survival and pulmonary function in patients with chronic obstructive pulmonary and cardiovascular disease: a systematic review and meta-analysis

AIMS

The aim of this study was to clarify the effect of β-blockers (BBs) on respiratory function and survival in patients with chronic obstructive pulmonary disease with cardiovascular disease (CVD), as well as the difference between the effects of cardioselective and noncardioselective BBs.

METHODS AND RESULTS

We searched for relevant literature in four electronic databases, namely, PubMed, EMBASE, Cochrane Library, and Web of Science, and compared the differences in various survival indicators between patients with chronic obstructive pulmonary disease taking BBs and those not taking BBs. Forty-nine studies were included, with a total sample size of 670 594. Among these, 12 studies were randomized controlled trials (RCTs; seven crossover and five parallel RCTs) and 37 studies were observational (including four post hoc analyses of data from RCTs). The hazard ratios (HRs) of chronic obstructive pulmonary disease exacerbation between patients with chronic obstructive pulmonary disease who were not treated with BBs and those who were treated with BBs, cardioselective BBs, and noncardioselective BBs were 0.77 [95% confidence interval (CI) 0.67, 0.89], 0.72 [95% CI 0.56, 0.94], and 0.98 [95% CI 0.71, 1.34, respectively] (HRs <1 indicate favouring BB therapy). The HRs of all-cause mortality between patients with chronic obstructive pulmonary disease who were not treated with BBs and those who were treated with BBs, cardioselective BBs, and noncardioselective BBs were 0.70 [95% CI 0.59, 0.83], 0.60 [95% CI 0.48, 0.76], and 0.74 [95% CI 0.60, 0.90], respectively (HRs <1 indicate favouring BB therapy). Patients with Chronic obstructive pulmonary disease treated with cardioselective BBs showed no difference in ventilation effect after the use of an agonist, in comparison with placebo. The difference in mean change in forced expiratory volume in 1 s was 0.06 [95% CI -0.02, 0.14].

CONCLUSION

The use of BBs in patients with chronic obstructive pulmonary disease is not only safe but also reduces their all-cause and in-hospital mortality. Cardioselective BBs may even reduce chronic obstructive pulmonary disease exacerbations. In addition, cardioselective BBs do not affect the action of bronchodilators. Importantly, BBs reduce the heart rate acceleration caused by bronchodilators. BBs should be prescribed freely when indicated in patients with chronic obstructive pulmonary disease and heart disease.

Plasma Metabolic Signature of Atherosclerosis Progression and Colchicine Treatment in Rabbits

Balloon catheter endothelial denudation in New Zealand white rabbits fed high cholesterol diet is a validated atherosclerosis model. Well-characterized in terms of atherosclerosis induction and progression, the metabolic changes associated with the atherosclerosis progression remain indeterminate. Non-targeted metabolomics permits to develop such elucidation and allows to evaluate the metabolic consequences of colchicine treatment, an anti-inflammatory drug that could revert these changes. 16 rabbits underwent 18 weeks of atherosclerosis induction by diet and aortic denudation. Thereafter animals were randomly assigned to colchicine treatment or placebo for 18 weeks while on diet. Plasma samples were obtained before randomization and at 36 weeks. Multiplatform (GC/MS, CE/MS, RP-HPLC/MS) metabolomics was applied. Plasma fingerprints were pre-processed, and the resulting matrixes analyzed to unveil differentially expressed features. Different chemical annotation strategies were accomplished for those significant features. We found metabolites associated with either atherosclerosis progression, or colchicine treatment, or both. Atherosclerosis was profoundly associated with an increase in circulating bile acids. Most of the changes associated with sterol metabolism could not be reverted by colchicine treatment. However, the variations in lysine, tryptophan and cysteine metabolism among others, have shown new potential mechanisms of action of the drug, also related to atherosclerosis progression, but not previously described.

Effects of Arginine Vasopressin on Migration and Respiratory Burst Activity in Human Leukocytes

Arginine vasopressin can bind to high-affinity vasopressin V1a receptors in human leukocytes. This study aims to investigate the effects of arginine vasopressin on migration and chemotaxis of neutrophils and oxygen free radical release by human leukocytes. Neutrophils and monocytes were obtained from peripheral blood samples of ten healthy volunteers. Leukocyte migration was microscopically assessed in a modified 48-blind well microchemotaxis chamber, and respiratory burst activity was estimated using 2',7'-dichlorofluorescin diacetate in descending concentrations of arginine vasopressin. Arginine vasopressin stimulates migration of monocytes and neutrophils depending on concentration and on interaction with other chemoattractants. The strongest chemotactic responses of monocytes to arginine vasopressin were observed in the micro and nanomolar range and in the nanomolar range for neutrophils (p<0.001). Pre-incubation of leukocytes with arginine vasopressin decreased migration of leukocytes in a dose-dependent manner. Arginine vasopressin did not stimulate release of oxygen free radicals by neutrophils. Arginine vasopressin stimulates in a dose-dependent manner the migration of monocytes and neutrophils. However, pre-incubation of leukocytes with arginine vasopressin decreased the migratory response of monocytes and neutrophils to other chemoattractants. These findings may be of importance in the treatment regimen of patients with septic shock.

Neutrophil stunning by metoprolol reduces infarct size

The β1-adrenergic-receptor (ADRB1) antagonist metoprolol reduces infarct size in acute myocardial infarction (AMI) patients. The prevailing view has been that metoprolol acts mainly on cardiomyocytes. Here, we demonstrate that metoprolol reduces reperfusion injury by targeting the haematopoietic compartment. Metoprolol inhibits neutrophil migration in an ADRB1-dependent manner. Metoprolol acts during early phases of neutrophil recruitment by impairing structural and functional rearrangements needed for productive engagement of circulating platelets, resulting in erratic intravascular dynamics and blunted inflammation. Depletion of neutrophils, ablation of Adrb1 in haematopoietic cells, or blockade of PSGL-1, the receptor involved in neutrophil-platelet interactions, fully abrogated metoprolol's infarct-limiting effects. The association between neutrophil count and microvascular obstruction is abolished in metoprolol-treated AMI patients. Metoprolol inhibits neutrophil-platelet interactions in AMI patients by targeting neutrophils. Identification of the relevant role of ADRB1 in haematopoietic cells during acute injury and the protective role upon its modulation offers potential for developing new therapeutic strategies.

Beta-blockers in COPD: time for reappraisal

The combined effects on the heart of smoking and hypoxaemia may contribute to an increased cardiovascular burden in chronic obstructive pulmonary disease (COPD). The use of beta-blockers in COPD has been proposed because of their known cardioprotective effects as well as reducing heart rate and improving systolic function. Despite the proven cardiac benefits of beta-blockers post-myocardial infarction and in heart failure they remain underused due to concerns regarding potential bronchoconstriction, even with cardioselective drugs. Initiating treatment with beta-blockers requires dose titration and monitoring over a period of weeks, and beta-blockers may be less well tolerated in older patients with COPD who have other comorbidities. Medium-term prospective placebo-controlled safety studies in COPD are warranted to reassure prescribers regarding the pulmonary and cardiac tolerability of beta-blockers as well as evaluating their potential interaction with concomitant inhaled long-acting bronchodilator therapy. Several retrospective observational studies have shown impressive reductions in mortality and exacerbations conferred by beta-blockers in COPD. However, this requires confirmation from long-term prospective placebo-controlled randomised controlled trials. The real challenge is to establish whether beta-blockers confer benefits on mortality and exacerbations in all patients with COPD, including those with silent cardiovascular disease where the situation is less clear.

Good news for β-blockers in perioperative medicine

Myocardial ischemia is a relatively frequent complication in patients undergoing non-cardiac surgery and β-blockers may have a protective effect. β-blockers reduce the oxygen supply:demand ratio, and exert anti-inflammatory and anti-arrhythmic effects. However, randomized trials, specifically conducted to test this hypothesis, yielded conflicting results. The absolute risk for cardiac mortality and morbidity during and after non-cardiac surgery varies between patient groups defined by surgical risk categories, making it difficult to establish a risk:benefit ratio. We discuss the hypothesis that the protective effect of β-blockers on cardiovascular outcome differs across the different risk classes of surgical procedures, thereby explaining the conflicting evidence across studies. In particular, we examine the results of a recent meta-analysis that suggests that β-blockers may reduce mortality in patients under going high-risk non-cardiac surgery.

ß-Blockers reduce mortality in patients undergoing high-risk non-cardiac surgery

BACKGROUND

ß-Adrenergic receptor antagonists (beta-blockers) are frequently used with the aim of reducing perioperative myocardial ischemia and infarction. However, randomized clinical trials specifically designed to evaluate the effects of beta-blockers on mortality in patients undergoing non-cardiac surgery have yielded conflicting results.

OBJECTIVE

This study aimed to examine the effect of perioperative ß-blockers on total and cardiovascular mortality in patients undergoing non-cardiac surgery.

METHODS

We conducted a meta-analysis of randomized clinical trials that examined the effects of ß-blockers versus placebo on cardiovascular and all-cause mortality in patients undergoing non-cardiac surgery. We extracted data from articles published before 30 November 2009 in peer-reviewed journals indexed in MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE and CINAHL. Data extraction was carried out independently by two reviewers on the basis of an intent-to-treat approach, and inconsistencies were discussed and resolved in conference. The present meta-analysis was undertaken according to the Quality of Reporting of Meta-analyses (QUORUM) statement.

RESULTS

A total of 2148 records were screened, from which we identified 74 randomized controlled trials for non-cardiac surgery. After excluding 49 studies that did not report the clinical outcome of interest or were subanalyses or presented duplicate data, the final search left 25 clinical trials. Treatment with ß-blockers had no significant effect on all-cause mortality (odds ratio [OR] 1.15; 95% confidence interval [CI] 0.92, 1.43; p = 0.2717) or cardiovascular mortality (OR 1.13; 95% CI 0.85, 1.51; p = 0.5855). However, surgical risk category markedly differed across the studies. According to Joint American College of Cardiology and American Heart Association guidelines for perioperative assessment of patients having non-cardiac surgery, five trials evaluated the effect of ß-blockers in patients treated with emergency and vascular surgery (high-risk category) whereas 15 and five trials evaluated the effect of ß-blockers in intermediate low and intermediate high surgical risk categories, respectively. Subgroup analyses showed that the surgical risk category and dose titration of ß-blockers to target heart rate affected the estimate of the effect of ß-blockers for all-cause and cardiovascular mortality. ß-Blockers reduced total mortality by 61% more in patients who underwent high-risk surgery than in those who underwent intermediate high- or intermediate low-risk surgery. When cardiovascular mortality was assessed, the benefit of ß-blockers was 74% greater in trials that titrated ßblockers to heart rate than in trials that did not, although formal statistical significance was not achieved.

CONCLUSIONS

These data suggest that ß-blockers may be useful for reducing mortality in patients who undergo high-risk non-cardiac surgery.

β-blockers and risk of all-cause mortality in non-cardiac surgery

Myocardial ischemia is a frequent complication in patients undergoing non-cardiac surgery and β-blockers may exert a protective effect. The main benefit of β-blockers in perioperative cardiovascular morbidity and mortality is believed to be linked to specific effects on myocardial oxygen supply and demand. β-blockers may exert anti-inflammatory and anti-arrhythmic effects. Randomized clinical trials which evaluated the effects of β-blockers on all-cause mortality in patients undergoing non-cardiac surgery have yielded conflicting results. In 9 trials, 10,544 patients with non-cardiac surgery were randomized to β-blockers (n = 5274) or placebo (n = 5270) and there were a total of 304 deaths. Patients randomized to β-blockers group showed a 19% increased risk of all-cause mortality (odds ratio [OR] 1.19, 95% confidence interval (CI) 0.95-1.50; p = 0.135). However, trials included in the meta-analysis differed in several aspects, and a significant degree of heterogeneity (I 2 = 46.5%) was noted. A recent analysis showed that the surgical risk category had a substantial influence on the overall estimate of the effect of β-blockers. Compared with patients in the intermediate-high-surgical-risk category, those in the high-risk category showed a 73% reduction in the risk of total mortality with β-blockers compared with placebo (OR 0.27, 95% CI 0.10-0.71, p = 0.016). These data suggest that perioperative β-blockers confer a benefit which is mostly limited to patients undergoing high-risk surgery.

The cardioprotection granted by metoprolol is restricted to its administration prior to coronary reperfusion

BACKGROUND

Myocardial infarct size is a strong predictor of cardiovascular events. Intravenous metoprolol before coronary reperfusion has been shown to reduce infarct size; however, it is unknown whether oral metoprolol initiated early after reperfusion, as clinical guidelines recommend, is similarly cardioprotective. We compared the extent of myocardial salvage associated with intravenous pre-reperfusion-metoprolol administration in comparison with oral post-reperfusion-metoprolol or placebo. We also studied the effect on suspected markers of reperfusion injury.

METHODS

Thirty Yorkshire-pigs underwent a reperfused myocardial infarction, being randomized to pre-reperfusion-metoprolol, post-reperfusion-metoprolol or placebo. Cardiac magnetic resonance imaging was performed in eighteen pigs at day 3 for the quantification of salvaged myocardium. The amounts of at-risk and infarcted myocardium were quantified using T2-weighted and post-contrast delayed enhancement imaging, respectively. Twelve animals were sacrificed after 24h for reperfusion injury analysis.

RESULTS

The pre-reperfusion-metoprolol group had significantly larger salvaged myocardium than the post-reperfusion-metoprolol or the placebo groups (31 ± 4%, 13 ± 6%, and 7 ± 3% of myocardium at-risk respectively). Post-mortem analyses suggest lesser myocardial reperfusion injury in the pre-reperfusion-metoprolol in comparison with the other 2 groups (lower neutrophil infiltration, decreased myocardial apoptosis, and higher activation of the salvage-kinase phospho-Akt). Salvaged myocardium and reperfusion injury pair wise comparisons proved there were significant differences between the pre-reperfusion-metoprolol and the other 2 groups, but not among the latter two.

CONCLUSIONS

The intravenous administration of metoprolol before coronary reperfusion results in larger myocardial salvage than its oral administration initiated early after reperfusion. If confirmed in the clinical setting, the timing and route of β-blocker initiation could be revisited.

Pathophysiological aspects of functional modulation of human peripheral blood neutrophils with propranolol

We studied the effect of beta-adrenoceptor antagonist propranolol on the regulation of spontaneous apoptosis in neutrophils, priming of lipopolysaccharide-treated neutrophils, and expression of neutrophil adhesion factors. The influence of propranolol on apoptosis, adhesion, and generation of oxygen radicals by neutrophils was shown to be an additional mechanism of the action of beta-adrenoceptor antagonists. This pathophysiological mechanism probably mediates the effect of neuroendocrine transmitters and explains the role of adrenergic antagonists in the pathogenesis and therapy of inflammation, cardiovascular diseases, and bronchial asthma.

Metoprolol treatment decreases tissue myeloperoxidase activity after spinal cord injury in rats

Neutrophil infiltration has been reported to play an important role in spinal cord injury (SCI). In addition to their cardioprotective effects, beta-blockers have been found to have neuroprotective effects on the central nervous system, but their effect on SCI has not yet been studied. In the current study, we investigated the effect of metoprolol on myeloperoxidase (MPO) activity, a marker of neutrophil activation, in the spinal cord after experimental SCI in rats. Rats were divided into six groups: controls received only laminectomy and spinal cord samples were taken immediately; the sham operated group received laminectomy, and spinal cord samples were taken 4h after laminectomy; the trauma only group underwent a 50g/cm contusion injury but received no medication; and three other groups underwent trauma as for the trauma group, and received 30mg/kg methylprednisolone, 1mg/kg metoprolol, or 1mL saline, respectively. All the medications were given intraperitoneally as single doses, immediately after trauma. Spinal cord samples were taken 4h after trauma and studied for MPO activity. The results showed that tissue MPO activity increased after injury. Both metoprolol and methylprednisolone treatments decreased MPO activity, indicating a reduction in neutrophil infiltration in damaged tissue. The effect of metoprolol on MPO activity was found to be similar to methylprednisolone. In view of these data, we conclude that metoprolol may be effective in protecting rat spinal cord from secondary injury.

Mechanisms involved in the reduced leukocyte migration in intrauterine undernourishment

OBJECTIVE

We investigated factors that may be involved in the reduced leukocyte migration observed in intrauterine undernourished rats.

METHODS

Male Wistar rat offspring (8-9 wk of age) of dams fed during pregnancy with 50% less food than control dams were used to measure L-selectin expression (by flow cytometry), bone marrow cell count, blood cell count, laminin and type IV collagen in the basal membrane of venules of the spermatic fascia (by immunohistochemistry), total protein level and serum albumin, and the production of leukotriene B4 after stimulation with tumor necrosis factor-alpha and corticosterone plasma levels (by enzyme-linked immunosorbent assay).

RESULTS

Hypocellularity in bone marrow and peripheral blood and reduced L-selectin expression were found in the undernourished rat offspring (UR) compared with nourished offspring (NR; P < 0.05). Type IV collagen in the basal membrane of the venules of the spermatic fascia was less in UR than in NR (P < 0.05). The total protein levels and serum albumin did not differ between the two groups. Leukotriene B4 production after stimulation with tumor necrosis factor-alpha was lower in UR (P < 0.05). These differences could not be attributed to circulating glucocorticoids levels, which were not different in the NR and UR groups.

CONCLUSION

Our data suggest that all observed differences contribute to reduced leukocyte migration in undernourishment.

Role of metoprolol, B1-adrenoceptor antagonist, thromboxane A2 and nitric oxide in CsA-induced hypertension

Chronic treatment with cyclosporine A (CsA), a potent immunosuppressive agent, is associated with the development of arterial hypertension. The effect of CsA on vascular responses was determined in Sprague-Dawley rats and rat aortic rings. Male rats weighing 250-300 g were given either CsA (25mg/kg/day) in olive oil or vehicle by intraperitoneal (ip) injection for 7 days. CsA administration produced a 42% increase (P<0.001) in mean arterial pressure (MAP) which reached a plateau after 3 days. The level of both nitrate/nitrite (NO(2)/NO(3)), metabolites of nitric oxide (NO), decreased by 50% (P<0.001), but the level of thromboxane A2 (TBXA2) increased by 75% (P<0.001), in the urine. When 10(-9)M of CsA was added acutely to intact aortic rings from untreated rats, NO(2)/NO(3) production decreased by 83% (P<0.011), but TBXA2 production increased by 86% (P<0.001). The effects of CsA were reversed both in vivo and in vitro by pretreatment with metoprolol (15 mg/kg/day ip), B1-adrenoceptor antagonist. There were no changes in MAP and tension in rats treated with metoprolol alone. In addition, in aorta of rats that were treated with CsA ip for 7 days, CsA significantly activated protein kinase C (PKC) translocation. This suggests that PKC mediate, in part, CsA-induced hypertension. In summary, CsA inhibits endothelial NO formation, activate PKC, and increase TBXA2 production, with resulting increase in MAP, and this changes can be overcome by pretreatment with metoprolol.

Involvement of cyclic adenosine monophosphate-dependent protein kinase A and pertussis toxin-sensitive G proteins in the migratory response of human CD14+ mononuclear cells to katacalcin

Katacalcin (KC) belongs to a small family of polypeptides that are encoded by the calc-1 gene and also include calcitonin (CT) and procalcitonin NH2-terminal cleavage peptide (N-ProCT). Biological roles of KC or N-ProCT are unknown. To determine whether these polypeptides affect leukocyte function, forearm venous blood polymorphonuclear neutrophils and CD14+ peripheral blood mononuclear cells (PBMCs) were isolated from healthy human donors. Cell migration was assessed in a blindwell chemotaxis chamber using nitrocellulose micropore filters. Cellular levels of cyclic adenosine monophosphate (cAMP) were measured by HPLC; activation of protein kinase A was studied by Western blot. Fluorochrome-labeled peptide binding to cells was studied by fluorescence-activated cell sorting (FACS) and intracellular calcium transients were studied by confocal microscopy with FLUO-3. KC elicited concentration-dependent migration of CD14+ PBMC at concentrations from the atomolar to the micromolar range and deactivated attractant-induced chemotaxis. CT N-terminal flanking peptide had no such effect. Neutrophils did not migrate toward any of those peptides and their oxygen-free radical release was not affected as measured fluorometrically. Functional responses of CD14+ PBMC to KC correlated to forskolin-sensitive cAMP accumulation in cells and were inhibited by protein kinase A inhibitor (PKI) and Rp diastereomer of adenosine 3',5'-cyclic monophosphorothioate. Treatment of CD14+ PBMC with KC activated protein kinase A(C alpha). Intracellular calcium was decreased with CT, KC, and procalcitonin (PCT). Binding studies showed that KC might share the binding site with CT and PCT. Data indicate that KC regulates human CD14+ PBMC migration via signaling events involving protein kinase A-dependent cAMP pathways.

Migration of human monocytes in response to procalcitonin

OBJECTIVE

Circulating serum levels of procalcitonin rise significantly during bacterial infection. Because calcitonin is known to be a monocyte chemoattractant, we investigated whether procalcitonin, a prohormone of calcitonin, also affects leukocyte migration.

DESIGN

Prospective, controlled in vitro study.

SETTING

University research laboratories.

INTERVENTIONS

Forearm venous blood polymorphonuclear neutrophils and monocytes were isolated from healthy human donors. Cell migration was assessed in a blindwell chemotaxis chamber. The distance of migration into filter micropores was measured. To biochemically confirm functional data on cell migration, effects of procalcitonin on cellular levels of cyclic adenosine monophosphate were measured by high-performance liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Both procalcitonin and calcitonin elicited dose-dependent migration of monocytes at concentrations from the femtomolar to the micromolar range. Neutrophils did not migrate toward procalcitonin or calcitonin, nor was their oxygen free radical release affected as measured fluorimetrically. Checkerboard analysis of monocyte locomotion revealed procalcitonin-induced migration as true chemotaxis. Pretreatment of monocytes with procalcitonin or calcitonin rapidly deactivated their migratory response to formyl-Met-Leu-Phe, and both also induced homologous deactivation of migration. Procalcitonin elevated levels of cyclic adenosine monophosphate in monocytes.

CONCLUSIONS

In vitro procalcitonin is a monocyte chemoattractant that deactivates chemotaxis in the presence of additional inflammatory mediators. Procalcitonin stimulates cyclic adenosine monophosphate production in monocytes, suggesting that its action may be specific and comparable with calcitonin, which exerts similar functions.

Significance of beta-blockers in the perioperative period

Beta-blockers have emerged as one of the key therapeutic agents that can decrease cardiac morbidity and mortality. Advances in cardiac beta-adrenergic receptor physiology and pharmacology have provided new insights into the beneficial effects of beta-blockers in cardiovascular medicine. Although significant advances have been made, many specific questions still remain to be answered. We will review some of these developments and the current role of beta-blockers in peri-operative medicine.

Effects of alcohol on the heart

Some evidence suggests that light to moderate alcohol consumption protects against cardiovascular diseases. However, this cardioprotective effect of alcohol consumption in adults is absent at the population level. Approximately 20 to 30% of patients admitted to a hospital are alcohol abusers. In medical practice, it is essential that patients' levels of consumption are known because of the many adverse effects that might result in the course of routine care. Ethanol damage to the heart is evident if alcohol consumption exceeds 90 to 100 g/d. Heavy ethanol consumption leads to increased risk for sudden cardiac death and cardiac arrhythmias. In patients with coronary heart disease, alcohol use was associated with increased mortality. An early response to drinking was an increased ventricular wall thickness to diameter ratio, possibly proceeding with continuous drinking to alcoholic cardiomyopathy, which had a worse outcome compared with idiopathic dilative cardiomyopathy if drinking was not stopped or at least reduced (< 60 g/d). In the ICU, patients with chronic alcoholism have more cardiac complications postoperatively. These complications probably are caused by biventricular dysfunction, particularly with the occurrence of severe infections or septic shock, events that are three to four times more frequent among chronic alcoholics than occasional drinkers or nondrinkers. To prevent further complications from drinking and for long-term management of drinking, patients with alcohol abuse and heart failure should be treated in brief intervention and follow-up programs. Prognosis is good even in patients with New York Heart Association class IV heart failure caused by cardiomyopathy if complete abstinence is accomplished. Noncompliance to smoking and alcohol restrictions, which are amenable to change, dramatically increases the risk for hospital readmissions among patients with heart failure.