Rapidly changing perspectives about mast cells at mucosal surfaces

Summary: Mast cells (MCs) are major effector cells of immunoglobulin E (IgE)‐mediated allergic inflammation. However, it has become increasingly clear that they also play important roles in diverse physiological and pathological processes. Recent advances have focused on the importance of MCs in both innate and adaptive immune responses and have fostered studies of MCs beyond the myopic focus on allergic reactions. MCs possess a variety of surface receptors and may be activated by inflammatory mediators, IgE, IgG, light chains, complement fragments, proteases, hormones, neuropeptides, and microbial products. Following activation, they produce a plethora of pro‐inflammatory mediators and participate in inflammatory reactions in many organs. This review focuses on the role of MCs in inflammatory reactions in mucosal surfaces with particular emphasis on their role in respiratory and gastrointestinal inflammatory conditions.     

Proteinase-activated receptor 2 activation in the airways enhances antigen-mediated airway inflammation and airway hyperresponsiveness through different pathways

BACKGROUND: Serine proteinases such as mast cell tryptase, trypsin-like enzymes, and certain allergens are important in the pathogenesis of asthma. These proteinases can activate the proteinase-activated receptor (PAR)-2, which has been shown to be upregulated in the airways of patients with asthma. OBJECTIVE: The purpose of this study was to investigate PAR-2 activation in the airways during allergen challenge and its effects on the 2 principle features of asthma, airway inflammation and airway hyperresponsiveness (AHR). METHODS: Proteinase-activated receptor 2 activating peptide SLIGRL-NH2 (PAR-2 activating peptide [ap]) or control peptide LSIGRL-NH2 (PAR-2 control peptide [cp]) was administered alone or in conjunction with ovalbumin intranasally to mice, and AHR and airway inflammation were evaluated. RESULTS: PAR2ap did not induce AHR or airway inflammation in ovalbumin-sensitized mice that had not been challenged with ovalbumin. When administered with ovalbumin, PAR-2ap enhanced AHR and airway inflammation compared with ovalbumin administered alone or with PAR-2cp. The enhanced AHR persisted for 5 days, whereas the enhancement to airway inflammation dissipated. Mice administered PAR-2ap alone during the 5 days after the final antigen challenge demonstrated an additional enhancement to airway inflammation compared with the control animals. PAR-2ap administered with allergen increased TNF and IL-5 mRNA in lung tissue and IL-13 and TNF in bronchoalveolar lavage fluid. CONCLUSION: Exogenous PAR-2 activation in parallel with allergen challenge enhances allergen-mediated AHR and airway inflammation through distinct mechanisms. PAR-2 activation can also enhance established airway inflammation even when dissociated from exposure to allergen. Therefore, PAR-2 activation may play a pathogenic role in the development of AHR and airway inflammation.     

Atrial septal defect: attenuation of respiratory variation in systolic and diastolic time intervals

The effects of pathologic states on right and left ventricular function have been studied extensively. However, there have been few studies on the interrelations between right and left ventricular function in normal human subjects and in patients with disease. Respiratory effects on ventricular interrelations reflected by diastolic time, right or left ventricular systolic time and ventricular performance (pre-ejection period/ejection time ratio) were studied in 12 normal subjects and 15 patients with a normal pressure-large shunt atrial septal defect. Simultaneous pulmonary artery (intracardiac manometer recordings) and left ventricular external recordings were performed in both groups. Left ventricular diastolic time increased with inspiration in the normal subjects and decreased in the patients with atrial septal defect (12.6 +/- 2.39 [1 SE] versus -13.4 +/- 3.48 ms, p less than 0.001). Left ventricular systolic time and ejection time decreased with inspiration in the normal group and remained unchanged in the patient group (-7.6 +/- 0.95 versus -0.9 +/- 0.77 ms, p less than 0.001 and -10.4 +/- 1.09 versus -1.7 +/- 0.80 ms, p less than 0.001, respectively). Left ventricular pre-ejection period/ejection time ratio increased with inspiration in the normal subjects and remained unchanged in the patients with atrial septal defect (0.03 +/- 0.008 versus 0 +/- 0.01, p less than 0.01). Right ventricular diastolic time decreased with inspiration in normal and patient groups (-8.8 +/- 1.6 versus -17 +/- 3.87 ms).(ABSTRACT TRUNCATED AT 250 WORDS)     

Factors determining left atrial kinetic energy in patients with chronic mitral valve disease

BACKGROUND: Increased left atrial (LA) work is a major contributor to LA fatigue, LA failure and atrial fibrillation in patients with mitral stenosis (MS) and mitral valvular regurgitation (MVR). The present study was undertaken to define factors that determine LA work in patients with chronic mitral valve disease. PATIENTS AND METHODS: Peak left atrial kinetic energy (LAKE)was used as an index of LA work in 14 patients with MS, 14 with MVR, and 19 normal subjects matched for age and gender with MS and MVR patients. LA stroke volume and ejection fraction were measured from the biplane area-length method using echo techniques. Peak LAKE was obtained from the formula 1/2 mv2, where m = LA stroke volume x 1.06 (blood's specific gravity) and v = transmitral Doppler A-wave velocity. RESULTS: Stepwise regression analysis often clinical and echocardiographic parameters demonstrated that in MS, mitral valve area (r2 = 0.43) and LA maximal volume (r2 = 0.62), in MVR, only LA maximal volume (r2 = 0.42) contributed independently to LAKE. LAKE was greater in MS and MVR compared to control subjects while LA ejection fraction was similar in all groups.CONCLUSIONS: It is concluded that LA work is markedly increased in patients with chronic mitral valve disease. Increased LA work in chronic mitral valve disease may contribute to LA fatigue, LA failure, and atrial fibrillation.     

Effect of statins on collagen type I degradation in patients with coronary artery disease and atrial fibrillation

The present study was undertaken to assess the effect of statins on collagen type I degradation and C-reactive protein in patients with coronary artery disease and atrial fibrillation. One hundred six patients with coronary artery disease and atrial fibrillation were studied: 40 (36 men, mean age 72 +/- 8 years) treated with a statin and 66 (48 men, mean age 74 +/- 9 years) not treated with a statin. Serum concentrations of carboxy-terminal telopeptide of collagen type I, an index of collagen type I degradation, and high-sensitivity C-reactive protein were measured in all patients. Carboxy-terminal telopeptide of collagen type I levels were significantly higher (p <0.001) in statin-treated patients (0.64 ng/ml, 95% confidence interval [CI] 0.57 to 0.71) compared with nonstatin-treated patients (0.38 ng/ml, 95% CI 0.31 to 0.44). These changes were independent of cholesterol levels (before or after therapy). Statin-treated patients had significantly lower (p <0.001) C-reactive protein levels (0.25 mg/dl, 95% CI 0.23 to 0.28) compared to statin nonusers (1.1 mg/dl, 95% CI 0.92 to 1.25). In conclusion, this study suggests that therapy with statins in patients with coronary artery disease and atrial fibrillation is associated with an increase in collagen degradation and an attenuation of inflammation, independently of cholesterol lowering.     

Postural exercise abnormalities in symptomatic patients with mitral valve prolapse

The hemodynamics of the supine and upright exercise response in 16 symptomatic women with mitral valve prolapse (Group I) was compared with that in 8 asymptomatic normal control women (Group II). All subjects had supine and upright echocardiography and phonocardiography at rest and none demonstrated mitral regurgitation. All participants then underwent same day graded bicycle exercise, with simultaneous radionuclide angiography in both the upright and the supine posture. Catecholamines were measured, and a variety of volumetric and hemodynamic data were obtained. Group I (patients with mitral valve prolapse) demonstrated a reduced exercise tolerance, especially during upright exercise, as measured by both total exercise duration and maximal work load achieved. Mean total catecholamine measurements were similar between the two study groups at comparable mean heart rate, mean blood pressure and mean rate-pressure (double) product. No difference was observed in the ratio of right to left ventricular stroke counts at rest or during exercise regardless of posture, suggesting that exercise-induced mitral regurgitation did not occur. A difference was noted, however, in left ventricular end-diastolic volume index. At rest, Group I patients exhibited a 42% decrease in this index when sitting upright, and this difference from supine values persisted at submaximal (300 kpm/min) and peak work loads (34 and 29% difference, respectively). This contrasted with the control subjects whose upright end-diastolic volumes at rest, at 300 kpm/min and at peak exercise were reduced 21, 10 and 3%, respectively, compared with supine values. Cardiac index measurements reflected the reduced left ventricular end-diastolic volume observed.(ABSTRACT TRUNCATED AT 250 WORDS)