Antibody Response after BNT162b2 Vaccination in Healthcare Workers Previously Exposed and Not Exposed to SARS-CoV-2.

The Pfizer/BioNtech Comirnaty vaccine (BNT162b2 mRNA COVID-19) against SARS-CoV-2 is currently in use in Italy. Antibodies to evaluate SARS-CoV-2 infection prior to administration are not routinely tested; therefore, two doses may be administered to asymptomatic previously exposed subjects. The aim of this study is to assess if any difference in antibody concentration between subjects exposed and not exposed to SARS-CoV-2 prior to BNT162b2 was present after the first dose and after the second dose of vaccine. Data were retrospectively collected from the clinical documentation of 337 healthcare workers who underwent SARS-CoV-2 testing before and after BNT162b2. Total anti RBD (receptor-binding domain) antibodies against SARS-CoV-2's spike protein were measured before and 21 days after the first dose, and 12 days after the second dose of BNT162b2. Twenty-one days after the first dose, there was a statistically significant difference in antibody concentration between the two groups, which was also maintained twelve days after the second dose. In conclusion, antibody response after receiving BNT162b2 is greater in subjects who have been previously exposed to SARS-CoV-2 than in subjects who have not been previously exposed to the virus, both after 21 days after the first dose and after 12 days from the second dose. Antibody levels, 21 days after the first dose, reached a titer considered positive by the test manufacturer in the majority of subjects who have been previously infected with SARS-CoV-2. Evaluating previous infection prior to vaccination in order to give the least effective number of doses should be considered.

Percutaneous coronary injection of bone marrow cells in small experimental animals: small is not too small.

Intracoronary infusion of bone marrow cells (BMCs) is thought to induce cardiac regeneration in ischemic heart disease and dilated cardiomyopathy. The aim of our study was to develop a new method to inject BMCs into coronary arteries of small experimental animals. Transient atrioventricular block (AVB) was induced in 25 rats and 39 hamsters by intracarotid injection of adenosine 5'-triphosphate (ATP). Contrast echocardiography was obtained. BMCs (0.2-0.5 ml) were collected through femoral puncture, stained with PKH26 and injected into the carotid artery (CA). Animals were immediately sacrificed or followed for 1 month. To evaluate BMCs transfer from CA to myocardium, AVB and BMCs injections were performed in 10 hamsters subjected to coronary ligation for 30 min. Induction of transient AVB was possible in all animals by injecting 20-30 mg of ATP. Animals recovered a basal cardiac activity spontaneously or by dopamine injection. Flash injection of contrast medium through the CA induced staining of aortic root, coronary arteries, and myocardium. BMCs injection was possible in all cases. No immediate or late ECG changes were observed. Immediately after injection in healthy animals, histological examination showed the presence of BMCs in small coronary arteries and, after 1 month, the absence of infarction. In ischemic hearts, the presence of BMCs in the myocardium was observed 24h after ischemia. ATP-induced AVB block allows for percutaneous intracoronary injection of BMCs in small experimental animals with no immediate or late mortality and morbidity. This method offers new perspectives for the investigation of BMCs coronary infusion and engraftment in heart diseases.

Experimental ischemic cardiomyopathy: insights into remodeling, physiological adaptation, and humoral response.

Ligation of the left anterior descending coronary artery (LAD) is used to induce experimental myocardial infarction (MI). Most previous studies have focused on the early postoperative period, while data on mid-term follow-up are scanty. This study examined the mid-term effects of LAD ligation in 95 MI rats and 28 controls. The following parameters were evaluated: systemic blood pressure (SBP), heart rate (HR), and plasma brain natriuretic peptide (BNP) level. In addition, M-mode and B-mode echocardiography, histologic examinations, and cardiac hydroxyproline assays were performed. Forty-seven perioperative and 5 late deaths were recorded. Left ventricular dilation, observed 1 mo after MI, did not progress with time. Septal thickening was similar in the 2 groups, while wall thickening was lower in the MI rats at 1 mo only. Stroke volume was diminished in MI rats, while cardiac output was depressed only at 1 and 2 mo, due to increased heart rate. SBP was unchanged and plasma BNP level was similar in the 2 groups. The infarcted area (mean +/- SD) was 35 +/- 10%. The ventricles in MI rats were heavier and had increased hydroxyproline content. In conclusion, these data show that LAD ligation is not only a model of acute MI, but at mid-term it provides a model of chronic ischemic dilated cardiomyopathy.

Serum from patients with acute coronary syndromes displays a proapoptotic effect on human endothelial cells: a possible link to pan-coronary syndromes.

BACKGROUND: Endothelial apoptosis of atherosclerotic lesions is a possible determinant for the stable-to-vulnerable plaque transition. Recent data support the notion that plaque activation may be a pan-coronary process, advocating the existence of circulating triggers. METHODS AND RESULTS: Serum from 40 healthy subjects (group 1) and 73 patients with stable angina (n=32; group 2) or acute coronary syndromes (n=41; group 3) was incubated with human umbilical vein endothelial cells. The percentage of apoptosis by flow cytometry and Fas, Bax, and Bcl-2 protein expression by immunoblotting were evaluated at entry in patients and control subjects and repeated after 12 months in group 3. At baseline, apoptotic nuclei were higher in group 3 (14+/-6%) than in group 2 (3.3+/-1.8%) and group 1 (1.35+/-0.8%) (P<0.001). Fas and Bcl-2 were increased in group 3 with respect to groups 1 and 2 (P<0.01). Coincubation of group 3 serum with anti-tumor necrosis factor-alpha and anti-interleukin-6 monoclonal antibodies did not affect the human umbilical vein endothelial cell apoptotic process, whereas addition of Trolox decreased apoptosis to <50%. The percentage of apoptosis in group 3 significantly correlated to the numbers of coronary complex lesions at angiography (r=0.58, P<0.0005). In group 3, apoptosis and the Bax/Bcl-2 ratio decreased at 1 year (P<0.0001, P<0.05 respectively). CONCLUSIONS: Serum from patients with acute coronary syndromes displays a proapoptotic effect on human endothelial cells, supporting the theory of the existence of circulating triggers potentially able to activate atherosclerotic lesions.

Cellular thiols redox status: a switch for NF-kappaB activation during myocardial post-ischaemic reperfusion.

Myocardial ischaemia/reperfusion induces NF-kappaB activation, but little is known about the stimuli through which it occurs. Aims of the study were to investigate whether: (a) oxidative stress induced by ischaemia/reperfusion is linked with NF-kappaB activation; (b) counteraction of oxidative stress by N-acetyl cysteine (NAC) reduces NF-kappaB activation. At this purpose, in isolated rat hearts, we induced mild (15 min) and severe (30 min) ischaemia; a group of the hearts submitted to severe ischaemia were treated with NAC. Our data indicate that reperfusion after severe ischaemia activates NF-kappaB: the presence of p65 in the nuclear extracts was 274.5+/-18.6% vs aerobia; (P<0.05) and an induced DNA-binding activity was detected. NF-kappaB translocation occurs in parallel with myocardial decrease in reduced glutathione and protein -SH (from 9.2+/-0.4 to 5.4+/-0.3 nmol/mg prot, P<0.01, and from 350.3+/-16.6 to 296.0+/-9.1 nmol/mg prot, P<0.05) and accumulation of oxidised glutathione-GSSG-(from 0.075+/-0.005 to 0.118+/-0.007 nmol/mg prot, P<0.01). When ischaemia/reperfusion does not result in any oxidative stress (in mild ischaemia or severe ischaemia plus NAC), NF-kappaB does not translocate. A significant correlation was found between the activation of NF-kappaB and the accumulation of GSSG in the myocardium. Our data indicate that an oxidative shift of cellular thiolic pools can modulate the genic transcription of the heart through NF-kappaB activation.