Angioedema Without Wheals: Challenges in Laboratorial Diagnosis.

Angioedema is a prevailing symptom in different diseases, frequently occurring in the presence of urticaria. Recurrent angioedema without urticaria (AE) can be hereditary (HAE) and acquired (AAE), and several subtypes can be distinguished, although clinical presentation is quite similar in some of them. They present with subcutaneous and mucosal swellings, affecting extremities, face, genitals, bowels, and upper airways. AE is commonly misdiagnosed due to restricted access and availability of appropriate laboratorial tests. HAE with C1 inhibitor defect is associated with quantitative and/or functional deficiency. Although bradykinin-mediated disease results mainly from disturbance in the kallikrein-kinin system, traditionally complement evaluation has been used for diagnosis. Diagnosis is established by nephelometry, turbidimetry, or radial immunodiffusion for quantitative measurement of C1 inhibitor, and chromogenic assay or ELISA has been used for functional C1-INH analysis. Wrong handling of the samples can lead to misdiagnosis and, consequently, mistaken inappropriate approaches. Dried blood spot (DBS) tests have been used for decades in newborn screening for certain metabolic diseases, and there has been growing interest in their use for other congenital conditions. Recently, DBS is now proposed as an efficient tool to diagnose HAE with C1 inhibitor deficiency, and its use would improve the access to outbound areas and family members. Regarding HAE with normal C1 inhibitor, complement assays' results are normal and the genetic sequencing of target genes, such as exon 9 of F12 and PLG, is the only available method. New methods to measure cleaved high-molecular-weight kininogen and activated plasma kallikrein have emerged as potential biochemical tests to identify bradykinin-mediated angioedema. Validated biomarkers of kallikrein-kinin system activation could be helpful in differentiating mechanisms of angioedema. Our aim is to focus on the capability to differentiate histaminergic AE from bradykinin-mediated AE. In addition, we will describe the challenges developing specific tests like direct bradykinin measurements. The need for quality tests to improve the diagnosis is well represented by the variability of results in functional assays.

Bradykinin, insulin, and glycemia responses to exercise performed above and below lactate threshold in individuals with type 2 diabetes.

The aim of this study was to analyze the acute responses of bradykinin, insulin, and glycemia to exercise performed above and below lactate threshold (LT) in individuals with type 2 diabetes mellitus (T2D). Eleven participants with a diagnosis of T2D randomly underwent three experimental sessions 72 h apart: 1) 20 min of exercise performed at 120% of LT (120%LT), 2) 20 min of exercise performed at 80% of LT (80%LT), and 3) 20 min of control session. Blood glucose was analyzed before, during, and at 45 min post-exercise. Bradykinin and insulin were analyzed before and at 45 min post-exercise. Both exercise sessions elicited a parallel decrease in glucose level during exercise (P≤0.002), with a greater decrease being observed for 120%LT (P=0.005). Glucose decreased 22.7 mg/dL (95%CI=10.3 to 35, P=0.001) at the 45 min post-exercise recovery period for 80%LT and decreased 31.2 mg/dL (95%CI=18.1 to 44.4, P<0.001) for 120%LT (P=0.004). Insulin decreased at post-exercise for 80%LT (P=0.001) and control (P≤0.035). Bradykinin increased at 45 min post-exercise only for 80%LT (P=0.013), but was unrelated to the decrease in glucose (r=-0.16, P=0.642). In conclusion, exercise performed above and below LT reduced glycemia independently of insulin, but exercise above LT was more effective in individuals with T2D. However, these changes were unrelated to the increase in circulating bradykinin.

Bradykinin, insulin, and glycemia responses to exercise performed above and below lactate threshold in individuals with type 2 diabetes

The aim of this study was to analyze the acute responses of bradykinin, insulin, and glycemia to exercise performed above and below lactate threshold (LT) in individuals with type 2 diabetes mellitus (T2D). Eleven participants with a diagnosis of T2D randomly underwent three experimental sessions 72 h apart: 1) 20 min of exercise performed at 120% of LT (120%LT), 2) 20 min of exercise performed at 80% of LT (80%LT), and 3) 20 min of control session. Blood glucose was analyzed before, during, and at 45 min post-exercise. Bradykinin and insulin were analyzed before and at 45 min post-exercise. Both exercise sessions elicited a parallel decrease in glucose level during exercise (P≤0.002), with a greater decrease being observed for 120%LT (P=0.005). Glucose decreased 22.7 mg/dL (95%CI=10.3 to 35, P=0.001) at the 45 min post-exercise recovery period for 80%LT and decreased 31.2 mg/dL (95%CI=18.1 to 44.4, P<0.001) for 120%LT (P=0.004). Insulin decreased at post-exercise for 80%LT (P=0.001) and control (P≤0.035). Bradykinin increased at 45 min post-exercise only for 80%LT (P=0.013), but was unrelated to the decrease in glucose (r=-0.16, P=0.642). In conclusion, exercise performed above and below LT reduced glycemia independently of insulin, but exercise above LT was more effective in individuals with T2D. However, these changes were unrelated to the increase in circulating bradykinin.

Comparative effects of a novel angiotensin-converting enzyme inhibitor versus captopril on plasma angiotensins after myocardial infarction.

The compound 4-tert-butyl-2,6-bis(thiomorpholin-4-ylmethyl)phenol (TBTIF) has molecular characteristics similar to angiotensin-converting enzyme (ACE) inhibitors of the sulfhydryl subclass. To assess its value as a new therapeutic agent, we performed a comparative analysis of the effect of TBTIF versus captopril on the circulating levels of angiotensin (Ang) peptides and bradykinin as well as ACE and ACE2 expression after myocardial infarction. Male Wistar rats were divided into four groups: (1) sham-operated rats; (2) rats subjected to 48 h of coronary artery ligation; (3) rats administered captopril (1 mg/kg, i.m.), and (4) a similar group of rats given TBTIF (1 mg/kg, i.m.). Both drugs were administered 30 min before coronary artery ligation and again 24 h later. Acute myocardial infarction lowered both systolic and left ventricular systolic blood pressures compared to the sham group and increased plasma levels of Ang I, Ang II, Ang(1-7) and Ang(1-12). Administration of either captopril or TBTIF reversed the increases in plasma angiotensins. Interestingly, the levels of plasma Ang(1-7) achieved by administration of TBTIF reached values higher than those recorded with captopril. Both agents reversed the decreases in plasma concentrations of bradykinin; in addition, TBTIF upregulated ACE expression, while both agents suppressed the ACE2 upregulation induced by myocardial infarction. These results demonstrate a beneficial effect of the novel compound TBTIF in suppressing the acute surge in the circulating renin-angiotensin system activity induced by myocardial infarction. The greater effects of this compound in augmenting plasma Ang(1-7) concentrations may be highly significant as drugs which augment the concentration of this heptapeptide will exert cardioprotective actions in part by suppressing the hypertrophic and profibrotic actions of Ang II.

Type 2 diabetes elicits lower nitric oxide, bradykinin concentration and kallikrein activity together with higher DesArg(9)-BK and reduced post-exercise hypotension compared to non-diabetic condition.

This study compared the plasma kallikrein activity (PKA), bradykinin concentration (BK), DesArg(9)-BK production, nitric oxide release (NO) and blood pressure (BP) response after moderate-intensity aerobic exercise performed by individuals with and without type 2 diabetes. Ten subjects with type 2 diabetes (T2D) and 10 without type 2 diabetes (ND) underwent three sessions: 1) maximal incremental test on cycle ergometer to determine lactate threshold (LT); 2) 20-min of constant-load exercise on cycle ergometer, at 90% LT and; 3) control session. BP and oxygen uptake were measured at rest and at 15, 30 and 45 min post-exercise. Venous blood samples were collected at 15 and 45 minutes of the recovery period for further analysis of PKA, BK and DesArg(9)-BK. Nitrite plus nitrate (NOx) was analyzed at 15 minutes post exercise. The ND group presented post-exercise hypotension (PEH) of systolic blood pressure and mean arterial pressure on the 90% LT session but T2D group did not. Plasma NOx increased ~24.4% for ND and ~13.8% for T2D group 15 min after the exercise session. Additionally, only ND individuals showed increases in PKA and BK in response to exercise and only T2D group showed increased DesArg(9)-BK production. It was concluded that T2D individuals presented lower PKA, BK and NOx release as well as higher DesArg(9)-BK production and reduced PEH in relation to ND participants after a single exercise session.

Angiotensin-(1-9) regulates cardiac hypertrophy in vivo and in vitro.

BACKGROUND: Angiotensin-(1-9) is present in human and rat plasma and its circulating levels increased early after myocardial infarction or in animals treated with angiotensin-converting enzyme inhibitor. However, the cardiovascular effects of this peptide are unknown. OBJECTIVE: To determine whether angiotensin-(1-9) is a novel anti-cardiac hypertrophy factor in vitro and in vivo and whether this peptide is involved in the pharmacological effects of cardiovascular drugs acting on the renin-angiotensin system. METHODS AND RESULTS: The administration of angiotensin-(1-9) to myocardial infarcted rats by osmotic minipumps (450 ng/kg per min, n = 6) vs. vehicle (n = 8) for 2 weeks decreased plasma angiotensin II levels, inhibited angiotensin-converting enzyme activity and also prevented cardiac myocyte hypertrophy. However, cardiac myocyte hypertrophy attenuation triggered by angiotensin-(1-9) was not modified with the simultaneous administration of the angiotensin-(1-7) receptor antagonist A779 (100 ng/kg per min, n = 6). In experiments in vitro with cultured cardiac myocytes incubated with norepinephrine (10 micromol/l) or with insulin-like growth factor-1 (10 nmol/l), angiotensin-(1-9) also prevented hypertrophy. In other experimental setting, myocardial infarcted rats (n = 37) were randomized to receive either vehicle (n = 12), enalapril (10 mg/kg per day, n = 12) or angiotensin II receptor blocker candesartan (10 mg/kg per day, n = 13) for 8 weeks. Both drugs prevented left ventricle hypertrophy and increased plasma angiotensin-(1-9) levels by several folds. Angiotensin-(1-9) levels correlated negatively with different left ventricular hypertrophy markers even after adjustment for blood pressure reduction. CONCLUSION: Angiotensin-(1-9) is an effective and a novel anti-cardiac hypertrophy agent not acting via the Mas receptor.

Kallikrein kinin system activation in post-exercise hypotension in water running of hypertensive volunteers.

Previous studies demonstrated a reduction in blood pressure level immediately after different types of exercises, like running, cycling and resistance training, a phenomenon called post-exercise hypotension (PEH). Since PEH can persist for hours it could be suggested as a non-pharmacological therapy for hypertensive individuals. Unfortunately, usually running is not recommended due to the high impact caused by its practice. Therefore running in water treadmill should be a better option, since the environment is completely different and causes lower impact. However it is not known whether PEH occurs in this situation. The objective of this work was to evaluate the existence of PEH after water running and to compare PEH promoted by running in two different environments. In addition, changes in plasmatic concentrations of the kallikrein kinin system (KKS) components were also evaluated. Sixteen hypertensive subjects were submitted to two exercise sessions, conventional running and water running, in two different occasions. The pattern of heart rate, blood pressure and plasmatic concentrations of KKS components immediately after and one hour after exercise were investigated. Results showed a maximal reduction in systolic and diastolic blood pressure 30 min after both exercise models (P<0.001), indicating that moderate water running promotes PEH with similar magnitude as compared to conventional running. Plasma kallikrein activity and bradykinin concentration increased immediately after exercise (P<0.05), but these parameters were not different in both exercise models. In conclusion, our findings show that water running, similarly to conventional running, can also provoke PEH and alterations in the KKS components.

Kininogen and prekallikrein increases in the blood of streptozotocin-diabetic rats are normalized by insulin in vivo and in vitro.

Twelve days following treatment with 50 mg/kg streptozotocin (STZ), male rats were diabetic, with a three-fold increase in blood glucose (P<0.001) and increased plasma bradykinin (BK) kininogen reserves of [high-(HK)- and low- (LK)-molecular-weight kininogens,+162%, P<0.01 and +63%, P=0.05, respectively], as determined by bioassay of BK released by trypsin from these precursors under standardized conditions. Administration of a single dose (10 U/kg i.v.) of regular insulin decreased plasma HK and LK to near non-diabetic values. Within 24 h these values had returned to levels characteristic of uncorrected diabetes. Prekallikrein (PK), the precursor of plasma kallikrein, an enzyme which releases BK from HK, was increased by 63.4% (P<0.05) in STZ-diabetes, but dropped to near normal levels following insulin treatment. Incubation of whole blood of normal or diabetic rats with 0.02-0.2 mU/ml regular insulin for 10 min at 37 C, decreased HK (P<0.01) and PK (P<0.05) and led to the appearance (P<0.05) of Arg-Pro-Pro-Gly-Phe, a partially stable product of BK metabolism, detected in the incubation media by an enzyme-linked immunosorbent assay (ELISA). Incubation of cell-free plasma insulin had no effect on these parameters, suggesting that blood cells, possibly neutrophils, are required by insulin for the activation of plasma PK to kallikrein leading to BK release. Insulin may be a factor modulating BK formation; its reduction in diabetes may explain increases of plasma kininogen and PK observed in this condition.

[Vasodilator hormonal agents in chronic heart failure: effect of angiotensin-converting enzyme inhibitors]. / Hormonas vasodilatadoras en la insuficiencia cardíaca crónica: efecto de la inhibición de la enzima convertidora de angiotensina.

BACKGROUND: Administration of angiotensin converting enzyme (ACE) inhibitors to patients with congestive heart failure (CHF) is associated to a decrease in the abnormal vasoconstrictor neurohormonal activity. This contributes to the sustained benefits of these drugs on symptoms and survival of patients with CHF. There is little information, however, regarding the effects of ACE inhibition on vasodilator and natriuretic hormones. AIM: To evaluate the chronic effects of enalapril, in addition to digitalis and diuretics in patients with chronic cardiac failure. PATIENTS AND METHODS: Nine patients with an idiopathic dilated cardiomyopathy (8 male, aged 48 to 76 years old) under treatment with digitalis and diuretics, received enalapril 20 mg bid during eight weeks. Before and after this treatment period resting left ventricular ejection fraction, functional class, plasma levels of atrial natriuretic factor and bradykinins (BK) and urinary excretion of kalikreins (BK) and prostaglandin E2 (PGE2) were measured. RESULTS: After enalapril therapy, there was a significant increase in maximal O2 consumption (14.8 +/- 1.2 to 18.6 +/- 1.5 ml/kg/min, p < 0.05) and radionuclide LV ejection fraction (27.4 +/- 1.1 to 31.4 +/- 0.9% p < 0.05). This was associated with a significant decrease in plasma ANP levels (559 +/- 158 to 178 +/- 54.8 pg/ml) and UK (391 +/- 112 to 243 +/- 92 Cu/24 h). CONCLUSIONS: The decrease in ANP levels, which is a well known marker of prognosis in CHF, could contribute to explain the sustained clinical benefits observed with ACE inhibitors in patients with CHF.

Hormonas vasodilatadoras en la insuficiencia cardíaca crónica: efecto de la inhibición de la enzima convertidora de angiotensina / Vasodilator hormones in chronic heart failure: effect of the inhibition of angiotensine converting enzyme

To evaluate the chronic effect of enalapril, in addition to digitalis and diuretics, in patients with chronic heart failure, nine patients with an idopathic dilated cardiomyopathy (8 males, aged 48 to 76 years old) under treatment with digitalis and diuretics, received enalapril 20 mg bid during eigth weeks. Before and after this treatment period resting left ventricular ejection fraction, functional class, plasma levels of atrial natriuretic factor and bradykinins (BK) and urinary excretion of kalikreins (BK) and prostaglandins E2 (PGE2) were measured. After enalapril therapy, there was a significant increase in maximal O2 consumption (14.8ñ1.2 to 18.6ñ1.5 ml/kg/min, p<0.05) and radionuclide LV ejection fraction (27.4ñ1.1 to 31.4ñ0.9 percent p<0.05). This was associated with a significant decrease in plasma ANP levels (559ñ158 to 178ñ54.8 pg/ml) and UK (391ñ112 to 243ñ92 Cu/24 h). The decrease in ANP levels, which is a well known marker of prognosis in CHF, could contribute to explain the sustained clinical benefits observed with ACE inhibitors in patients with CHF

Bradykinin metabolism pathway in the rat pulmonary circulation.

OBJECTIVE: The contribution made by different enzymes to the degradation of bradykinin in physiological conditions was estimated by examining bradykinin metabolism in rat serum, in the in situ perfused lung and in vivo. METHODS: Dose-response curves for the hypotensive effect of intra-arterially and intravenously injected bradykinin were obtained in unanaesthetized rats. High-performance liquid chromatography was used to analyse the products of bradykinin breakdown after incubation with rat serum and perfusion through in situ lung preparations. RESULTS: In rat serum, kininase I degraded 34% and kininase II 11% of bradykinin, no evidence for other activities being detected. In the awake rat, D,L-2-mercaptomethyl-3-guanidino-ethylthiopropionic acid, an inhibitor of kininase I, did not reduce the percentage of bradykinin inactivation in the pulmonary circulation. In the in situ perfused lung 65% of bradykinin was metabolized and the main products were BK1-7, BK1-5 and BK4-9. Enalaprilat (an inhibitor of kininase II) blocked the formation of BK1-7 and BK1-5 and increased the recovery of BK4-9. beta-Mercapto-ethanol, which inhibits aminopeptidase P, and diprotin A, a specific inhibitor of dipeptidylaminopeptidase IV, both reduced the formation of BK4-9. Diprotin A also allowed the recovery of BK2-9. Bradykinin degradation and BK4-9 recovery were not affected by endopeptidase inhibitors. CONCLUSIONS: Our results show that the main degradation pathway of bradykinin in the lung is through the action of kininase II at the carboxyl terminus, and sequential cleavage by aminopeptidase P followed by dipeptidylaminopeptidase IV at the amino terminus. The amino-terminal degradation of bradykinin represents about 38% of the total lung kininase activity.

Pulmonary kinin metabolism and conversion of angiotensin I in spontaneously hypertensive rats.

OBJECTIVE: To examine the metabolism of kinins and angiotensin I in the pulmonary circulation of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (NWR). METHODS: Bradykinin inactivation was estimated in vivo by comparison of the hypotensive effect of intra-arterial and intravenous injections, and in the in situ perfused lung by analysing the breakdown products using high-performance liquid chromatography. RESULTS: In vivo pulmonary degradation of bradykinin, but not that of higher homologues of this peptide, was shown to be significantly greater in SHR. Angiotensin I converting activity was found to be increased in lungs of SHR. The recovery of bradykinin and homologues from perfused SHR lung was decreased relative to NWR. Des-(Phe-Arg) fragments of all kinin analogues were identified in the pulmonary perfusates. When bradykinin and des-Arg9-bradykinin were injected in the perfused lungs, the respective fragments 4-9 and 4-8 were also identified in the perfusates. When kininase II was inhibited with enalaprilat, the recovery of bradykinin increased from 10 to 43% in SHR and from 23 to 58% in NWR, whereas about 90% of the higher bradykinin homologues were recovered in both SHR and NWR. Aminopeptidase P and dipeptidylaminopeptidase IV, as measured by the recovery of fragment 4-9 under kininase II inhibition, accounted for about 40% of the total pulmonary kininase activity in the SHR lungs and 25% of that of the NWR lungs. CONCLUSIONS: The results show that SHR have increased kininase and angiotensin converting activity compared with NWR, and that kinins as well as angiotensin may contribute to the pathogenesis of hypertension. Aminopeptidase P and dipeptidylaminopeptidase IV may contribute to the increased in vivo degradation of bradykinin observed in the SHR.