Suppression of β1-adrenoceptor autoantibodies is involved in the antiarrhythmic effects of omega-3 fatty acids in male and female hypertensive rats

The arrhythmogenic potential of β1-adrenoceptor autoantibodies (β1-AA), as well as antiarrhythmic properties of omega-3 in heart diseases, have been reported while underlying mechanisms are poorly understood. We aimed to test our hypothesis that omega-3 (eicosapentaenoic acid-EPA, docosahexaenoic acid-DHA) may inhibit matrix metalloproteinase (MMP-2) activity to prevent cleavage of β1-AR and formation of β1-AA resulting in attenuation of pro-arrhythmic connexin-43 (Cx43) and protein kinase C (PKC) signaling in the diseased heart. We have demonstrated that the appearance and increase of β1-AA in blood serum of male and female 12-month-old spontaneously hypertensive rats (SHR) was associated with an increase of inducible ventricular fibrillation (VF) comparing to normotensive controls. In contrast, supplementation of hypertensive rats with omega-3 for two months suppressed β1-AA levels and reduced incidence of VF. Suppression of β1-AA was accompanied by a decrease of elevated myocardial MMP-2 activity, preservation of cardiac cell membrane integrity and Cx43 topology. Moreover, omega-3 abrogated decline in expression of total Cx43 as well as its phosphorylated forms at serine 368 along with PKC-ε, while decreased pro-fibrotic PKC-δ levels in hypertensive rat heart regardless the sex. The implication of MMP-2 in the action of omega-3 was also demonstrated in cultured cardiomyocytes in which desensitization of β1-AR due to permanent activation of β1-AR with isoproterenol was prevented by MMP-2 inhibitor or EPA. Collectively, these data support the notion that omega-3 via suppression of β1-AA mechanistically controlled by MMP-2 may attenuate abnormal of Cx43 and PKC signaling; thus, abolish arrhythmia substrate and protect rats with an advanced stage of hypertension from malignant arrhythmias

Chronic Chagas disease: from basics to laboratory medicine

Chagas disease, caused by Trypanosoma cruzi infection, is ranked as the most serious parasitic disease in Latin America and has huge potential to become a worldwide problem, due to increasing migration, and international tourism, as well as infectant transfer by blood contact and transfusion, intrauterine transfer, and organ transplantation. Nearly 30% of chronically-infected patients become symptomatic, often with a latency of 10-30 years, developing life-threatening complications. Of those, nearly 90% develop Chagas heart disease, while the others manifest gastrointestinal disease and neuronal disorders. Besides interrupting the infection cycle and chemotherapeutic infectant elimination, starting therapy early in symptomatic patients is important for counteracting the disease. This would be essentially supported by optimized patient management, involving risk assessment, early diagnosis and monitoring of the disease and its treatment. From economic and logistic viewpoints, the tools of laboratory medicine should be especially able to guarantee this. After summarizing the basics of chronic Chagas disease, such as the epidemiological data, the pathogenetic mechanisms thought to drive symptomatic Chagas disease and also treatment options, we present tools of laboratory medicine that address patient diagnosis, risk assessment for becoming symptomatic and guidance, focusing on autoantibody estimation for risk assessment and heart marker measurement for patient guidance. In addition, increases in levels of inflammation and oxidative stress markers in chronic Chagas disease are discussed

Hypertension in response to IL-6 during pregnancy: role of AT1-receptor activation

BACKGROUND: Increases in interleukin 6 (IL-6) and agonistic autoantibodies to the angiotensin II type 1 receptor (AT1-AA) are proposed to be important links between placental ischemia and hypertension in preeclampsia. METHODS: The purpose of this study was to determine whether IL-6 (5 ng/day), infused into normal pregnant (NP) rats, increased mean arterial pressure (MAP) and AT1-AA. MAP was analyzed in the presence and absence of an angiotensin type 1 receptor (AT1R) antagonist, losartan, L. RESULTS: MAP and AT1-AA increased from 102 ± 2 to 118 ± 4 mmHg and 0.7 ± 0.3 NP to 14.1 ± 1.4 chronotropic units with chronic IL-6 infusion. MAP responses to IL-6 were abolished in losartan pretreated rats (85 ± 4 in NP + L vs 85 ± 3 mmHg in IL-6 + L). CONCLUSION: These data indicate that IL-6 stimulates AT1-AA and that activation of the AT1R mediates IL-6 induced hypertension during pregnancy

Functional autoantibodies against G-protein coupled receptors in patients with persistent Long-COVID-19 symptoms

Impairment of health after overcoming the acute phase of COVID-19 is being observed more and more frequently. Here different symptoms of neurological and/or cardiological origin have been reported. With symptoms, which are very similar to the ones reported but are not caused by SARS-CoV-2, the occurrence of functionally active autoantibodies ((f)AABs) targeting G-protein coupled receptors (GPCR-(f)AABs) has been discussed to be involved. We, therefore investigated, whether GPCR-(f)AABs are detectable in 31 patients suffering from different Long-COVID-19 symptoms after recovery from the acute phase of the disease. The spectrum of symptoms was mostly of neurological origin (29/31 patients), including post-COVID-19 fatigue, alopecia, attention deficit, tremor and others. Combined neurological and cardiovascular disorders were reported in 17 of the 31 patients. Two recovered COVID-19 patients were free of follow-up symptoms. All 31 former COVID-19 patients had between 2 and 7 different GPCR-(f)AABs that acted as receptor agonists. Some of those GPCR-(f)AABs activate their target receptors which cause a positive chronotropic effect in neonatal rat cardiomyocytes, the read-out in the test system for their detection (bioassay for GPCR-(f)AAB detection). Other GPCR-(f)AABs, in opposite, cause a negative chronotropic effect on those cells. The positive chronotropic GPCR-(f)AABs identified in the blood of Long-COVID patients targeted the β(2)-adrenoceptor (β(2)-(f)AAB), the α1-adrenoceptor (α(1)-(f)AAB), the angiotensin II AT1-receptor (AT1-(f)AAB), and the nociceptin-like opioid receptor (NOC-(f)AAB). The negative chronotropic GPCR-(f)AABs identified targeted the muscarinic M(2)-receptor (M(2)-(f)AAB), the MAS-receptor (MAS-(f)AAB), and the ETA-receptor (ETA-(f)AAB). It was analysed which of the extracellular receptor loops was targeted by the autoantibodies

Long-acting beta(2)-agonist in addition to tiotropium versus either tiotropium or long-acting beta(2)-agonist alone for chronic obstructive pulmonary disease

BackgroundLong-acting bronchodilators comprising long-acting beta(2)-agonists and the anticholinergic agent tiotropium are commonly used for managing persistent symptoms of chronic obstructive pulmonary disease. Combining these treatments, which have different mechanisms of action, may be more effective than the individual components. However, the benefits and risks of combining tiotropium and long-acting beta2-agonists for the treatment of chronic obstructive pulmonary (COPD) disease are unclear.ObjectivesTo assess the relative effects of treatment with tiotropium in addition to long-acting beta(2)-agonist compared to tiotropium or long-acting beta2-agonist alone in patients with chronic obstructive pulmonary disease.Search methodsWe searched the Cochrane Airways Group Specialised Register of trials and clinicaltrials.gov up to January 2012.Selection criteriaWe included parallel group, randomised controlled trials of three months or longer comparing treatment with tiotropium in addition to long-acting beta2-agonist against tiotropium or long-acting beta2-agonist alone for patients with chronic obstructive pulmonary disease.Data collection and analysisTwo review authors independently assessed trials for inclusion and then extracted data on trial quality and the outcome results. We contacted study authors for additional information. We collected information on adverse effects from the trials.Main resultsFive trials were included in this review, mostly recruiting participants with moderate or severe chronic obstructive pulmonary disease. All of them compared tiotropium in addition to long-acting beta(2)-agonist to tiotropium alone, but only one trial additionally compared a combination of the two types of bronchodilator with long-acting beta2-agonist (formoterol) alone. Two studies used the long-acting beta2-agonist indacaterol, two used formoterol and one used salmeterol.Compared to tiotropium alone (3263 patients), treatment with tiotropium plus long-acting beta2-agonist resulted in a slightly larger improvement in the mean health-related quality of life (St George's Respiratory Questionnaire (SGRQ) MD -1.61; 95% CI -2.93 to -0.29). In the control arm, tiotropium alone, the SGRQ improved by falling 4.5 units from baseline and with both treatments the improvement was a fall of 6.1 units from baseline (on average). High withdrawal rates in the trials increased the uncertainty in this result, and the GRADE assessment for this outcome was therefore moderate. There were no significant differences in the other primary outcomes (hospital admission or mortality).The secondary outcome of pre-bronchodilator FEV1 showed a small mean increase with the addition of long-acting beta2-agonist (MD 0.07 L; 95% CI 0.05 to 0.09) over the control arm, which showed a change from baseline ranging from 0.03 L to 0.13 L on tiotropium alone. None of the other secondary outcomes (exacerbations, symptom scores, serious adverse events, and withdrawals) showed any statistically significant differences between the groups. There were wide confidence intervals around these outcomes and moderate heterogeneity for both exacerbations and withdrawals.The results from the one trial comparing the combination of tiotropium and long-acting beta2-agonist to long-acting beta2-agonist alone (417 participants) were insufficient to draw firm conclusions for this comparison.Authors' conclusionsThe results from this review indicate a small mean improvement in health-related quality of life for patients on a combination of tiotropium and long-acting beta2-agonist compared to tiotropium alone, but it is not clear how clinically important this mean difference may be. Hospital admission and mortality have not been shown to be altered by adding long-acting beta(2)-agonists to tiotropium. There were not enough data to determine the relative efficacy and safety of tiotropium plus long-acting beta2-agonist compared to long-acting beta2-agonist alone. There were insufficient data to make comparisons between the different long-acting beta2-agonists when used in addition to tiotropium

CD4(+) T cells play a critical role in mediating hypertension in response to placental ischemia

Similar to preeclamptic women, hypertension in the chronic Reduced Uterine Perfusion Pressure Rat Model Of Preeclampsia (RUPP) is associated with increased CD4+ T cells, cytokines, sFlt-1 and agonistic autoantibodies to the AngII receptor (AT1-AA). We examined the effect inhibition of T cell co-stimulation in RUPP rats treated with (A) (abatacept, 250 mg/kg, infused i.v. at gestation day 13), on hypertension and sFlt-1, TNF-alpha and AT1-AA. RUPP surgical procedure was performed on day 14. On day 19 MAP increased from 94+2 mmHg in Normal Pregnant (NP) to 123 +/- 3 mmHg in RUPP control rats. This response was attenuated by Abatacept, MAP was 104 +/- 2 mmHg in RUPP +/- A, and 96 +/- 2 mmHg NP +/- A. Percent circulating CD4+ T cells were 66 +/- 3% in RUPPs compared to 55 +/- 3% NP rats (p<0.04) but were normalized in RUPP +/- A rats (54 +/- 3%). The twofold increase in TNF alpha seen in RUPPs (277 +/- 47 pg/ml) was decreased to 80 +/- 18 pg/ml in RUPP+A. Placental sFlt-1 was reduced 70 % to 151 +/- 28 in RUPP +/- A compared 488 +/- 61 pg/ml in RUPP (p<0.001). AT1-AA decreased from 20 +/- 0.8 bpm in control RUPP to 6 +/- 0.7 bpm in RUPP +/- A. We next determined the effect of RUPP in causing hypertension in pregnant T cell deficient rats by examining MAP in NP (123 +/- 5 mmHg) and RUPP athymic nude rats (123 +/- 7 mmHg). In the absence of T cells, hypertension in response to placental ischemia was completely abolished. Collectively these data indicate that CD4+ Tcells in response to placental ischemia play an important role in the pathophysiology of hypertension associated with preeclampsia

The angiotensin II type I receptor contributes to impaired cerebral blood flow autoregulation caused by placental ischemia in pregnant rats

BACKGROUND: Placental ischemia and hypertension, characteristic features of preeclampsia, are associated with impaired cerebral blood flow (CBF) autoregulation and cerebral edema. However, the factors that contribute to these cerebral abnormalities are not clear. Several lines of evidence suggest that angiotensin II can impact cerebrovascular function; however, the role of the renin angiotensin system in cerebrovascular function during placental ischemia has not been examined. We tested whether the angiotensin type 1 (AT1) receptor contributes to impaired CBF autoregulation in pregnant rats with placental ischemia caused by surgically reducing uterine perfusion pressure. METHODS: Placental ischemic or sham operated rats were treated with vehicle or losartan from gestational day (GD) 14 to 19 in the drinking water. On GD 19, we assessed CBF autoregulation in anesthetized rats using laser Doppler flowmetry. RESULTS: Placental ischemic rats had impaired CBF autoregulation that was attenuated by treatment with losartan. In addition, we examined whether an agonistic autoantibody to the AT1 receptor (AT1-AA), reported to be present in preeclamptic women, contributes to impaired CBF autoregulation. Purified rat AT1-AA or vehicle was infused into pregnant rats from GD 12 to 19 via mini-osmotic pumps after which CBF autoregulation was assessed. AT1-AA infusion impaired CBF autoregulation but did not affect brain water content. CONCLUSIONS: These results suggest that the impaired CBF autoregulation associated with placental ischemia is due, at least in part, to activation of the AT1 receptor and that the RAS may interact with other placental factors to promote cerebrovascular changes common to preeclampsia

Rodenticide residues in non-target small mammal species and their occurrence in owl pellets

OBJECTIVES: Distinguishing the patterns of autoantibodies (AAB) against G-protein-coupled receptors in Chagas' cardiomyopathy and megacolon and the discovery of such a pattern in patients who are as yet asymptomatic could help to identify patients at high risk of developing the life-threatening complications of Chagas' disease. BACKGROUND: Such AAB against receptors as beta 1 (beta1-AAB), beta 2 (beta2-AAB), and muscarinergic 2 (M2-AAB) are thought to be involved in the pathogenesis of Chagas' cardiomyopathy and megacolon, the predominant manifestations of Chagas' disease, which is the most serious parasitic disease in Latin America. METHODS: Beta1-AAB, beta2-AAB, and M2-AAB were measured in the serum of asymptomatic Chagas' patients and in those with cardiomyopathy and/or megacolon. RESULTS: Nearly all Chagas' patients with cardiomyopathy and/or megacolon had AAB. Predominance of beta1-AAB combined with M2-AAB in Chagas' cardiomyopathy and beta2-AAB with M2-AAB in megacolon was found. Such patterns were also found in 34% of the asymptomatic patients, of whom 85% possessed a beta1-AAB level typical for Chagas' cardiomyopathy. CONCLUSIONS: The percentage of asymptomatic Chagas' patients who had a specific AAB pattern and had a beta1-AAB level above a defined cutoff point mirrors very well the epidemiological situation, which showed that clinical manifestations develop in nearly 30% of Chagas' patients and cardiomyopathy in nearly 90% of them. We hypothesize that beta1-, beta2-, and M2-AAB measurement might be a useful tool for risk assessment in the indeterminate state of Chagas' disease to select patients for earlier involvement in care programs. However, prospective studies are needed to further evaluate this hypothesis

Circulating angiotensin II type I receptor – autoantibodies in diabetic pregnancies

Pregnant women with either pre-existing or gestational diabetes mellitus are at increased risk of preeclampsia as well as future cardiovascular disease. The renin-angiotensin system is dysregulated in both diabetes mellitus and preeclampsia. In preeclampsia, maternal levels of circulating agonistic autoantibodies against the angiotensin II Type I receptor (AT1-AAs) are increased. Circulating AT1-AAs are thought to contribute to both the pathophysiology of preeclampsia and the increased risk of future cardiovascular disease. Studies exploring AT1-AA in diabetes outside pregnancy suggest their potential for both metabolic and cardiovascular pathogenicity. No studies have investigated AT1-AAs in diabetic pregnancies. We hypothesized elevated maternal circulating AT1-AA levels in pregnancies complicated by any type of diabetes mellitus. Third-trimester maternal serum from 39 women (controls: n= 10; type 1 diabetes: n= 9; type 2 diabetes: n=10; gestational diabetes=10) were analyzed for AT1-AA using an established bioassay method. Circulating AT1-AAs were present in 70% (7/10) of the controls and 83% (24/29) of the diabetes group (P=0.399). Presence of AT1-AA was correlated to hsCRP levels (P=0.036), but neither with maternal circulating angiogenic factors (soluble fms-like tyrosine kinase-1 and placental growth factor), nor with maternal or fetal characteristics indicative of metabolic disease or placental dysfunction. Our study is the first to demonstrate presence of circulating AT1-AAs in pregnant women with any type of diabetes. Our findings suggest AT1-AAs presence in pregnancy independently of placental dysfunction, nuancing the current view on their pathogenicity. Whether AT1-AAs per se contribute to increased risk of adverse pregnancy outcomes and future cardiovascular disease remains currently unanswered

Autoantibodies Activating the β2-Adrenergic Receptor Characterize Patients With Primary and Secondary Glaucoma

Recently, agonistic autoantibodies (agAAb) activating the β2-adrenergic receptor were detected in primary open-angle glaucoma (POAG) or ocular hypertension (OHT) patients and were linked to intraocular pressure (IOP) (1). The aim of the present study was to quantify β2-agAAb in the sera of glaucoma suspects and patients with primary and secondary glaucoma. Patients with OHT (n = 33), pre-perimetric POAG (pre-POAG; n = 11), POAG (n = 28), and 11 secondary OAG (SOAG) underwent ophthalmological examinations including examinations with Octopus G1 perimetry and morphometry. Twenty-five healthy individuals served as controls. Serum-derived IgG samples were analyzed for β2-agAAb using a functional bioassay. The beat-rate-increase of spontaneously beating cultured neonatal rat cardiomyocytes was monitored with 1.6 beats/15 s as cut-off. None of the sera of normal subjects showed β2-agAAb. In POAG or OHT patients increased beating rates of 4.1 ± 2.2 beats/15 s, and 3.7 ± 2.8 beats/15 s were detected (p > 0.05). Glaucoma patients with (POAG) and without perimetric (pre-POAG) defects did not differ (pre-POAG 4.4 ± 2.6 beats/15 s, POAG 4.1 ± 2.0 beats/15 s, p > 0.05). Patients with SOAG yielded mean beating rates of 4.7 ± 1.7 beats/15 s (p > 0.05). β2-agAAb were seen in 73% of OHT, 82% of pre-POAG, 82% of POAG, and 91% SOAG patients (p 0.05). The robust β2-agAAb seropositivity in patients with OHT, pre-POAG, POAG, and SOAG suggest a primary common role for β2-agAAb starting early in glaucoma pathophysiology and turned out to be a novel marker identifying all patients with increased IOP independent of glaucoma stage and entity