Helicobacter pylori versus the Host: Remodeling of the Bacterial Outer Membrane Is Required for Survival in the Gastric Mucosa

Modification of bacterial surface structures, such as the lipid A portion of lipopolysaccharide (LPS), is used by many pathogenic bacteria to help evade the host innate immune response. Helicobacter pylori, a gram-negative bacterium capable of chronic colonization of the human stomach, modifies its lipid A by removal of phosphate groups from the 1- and 4′-positions of the lipid A backbone. In this study, we identify the enzyme responsible for dephosphorylation of the lipid A 4′-phosphate group in H. pylori, Jhp1487 (LpxF). To ascertain the role these modifications play in the pathogenesis of H. pylori, we created mutants in lpxE (1-phosphatase), lpxF (4′-phosphatase) and a double lpxE/F mutant. Analysis of lipid A isolated from lpxE and lpxF mutants revealed lipid A species with a 1 or 4′-phosphate group, respectively while the double lpxE/F mutant revealed a bis-phosphorylated lipid A. Mutants lacking lpxE, lpxF, or lpxE/F show a 16, 360 and 1020 fold increase in sensitivity to the cationic antimicrobial peptide polymyxin B, respectively. Moreover, a similar loss of resistance is seen against a variety of CAMPs found in the human body including LL37, β-defensin 2, and P-113. Using a fluorescent derivative of polymyxin we demonstrate that, unlike wild type bacteria, polymyxin readily associates with the lpxE/F mutant. Presumably, the increase in the negative charge of H. pylori LPS allows for binding of the peptide to the bacterial surface. Interestingly, the action of LpxE and LpxF was shown to decrease recognition of Helicobacter LPS by the innate immune receptor, Toll-like Receptor 4. Furthermore, lpxE/F mutants were unable to colonize the gastric mucosa of C57BL/6J and C57BL/6J tlr4 -/- mice when compared to wild type H. pylori. Our results demonstrate that dephosphorylation of the lipid A domain of H. pylori LPS by LpxE and LpxF is key to its ability to colonize a mammalian host

Fluoroless catheter ablation of supraventricular and ventricular arrhythmias in pregnancy: validation of a standard approach in a large multicenter registry

Abstract Background An increasing experience in zero- (ZF) or near-zero fluoroscopy catheter ablation (CA) supports the implementation of early, fluoroless approach for recurrent, symptomatic arrhythmias in pregnancy. Purpose The aim of the study was to evaluate the feasibility, efficacy, and safety of CA with a standardized ZF approach during pregnancy. Methods Data were derived from a large prospective multicenter registry (ELEKTRO-RARE-A-CAREgistry). Between 2012 and 2019, more than 2655 CA procedures were performed in women in intention-to-treat using a ZF fluoroscopy approach. The procedures were performer using: 1) femoral access, 2) double-catheter technique, without intracardiac echocardiography, 3) electroanatomic mapping system (Ensite, Abbott, USA) for mapping and navigation, 4) conscious, light sedation. Shared decision making approach was applied, including a pregnancy heart team consultations. Results The study group consisted of 18 pregnant women (mean age: 30.3±5.0 years; range: 19–38 years; mean gestational age during CA: 21.4±9.2 weeks; range: 7–36 weeks). All pregnant women had no overt structural heart disease. Among women in reproductive age, pregnant women referred for ZF-CA approach accounted for approximately 2% of procedures. In the study group, the major indications for CA included: AVNRT (n=10); OAVRT/WPW (n=2); focal idiopathic ventricular arrhythmia (n=4), AT (n=1) and AF (n=1). Five women had double substrate for CA. In AF case general anesthesia and transesophageal echocardiography were used to monitor ZF-transseptal puncture and right-sided pulmonary vein isolation. All procedures were successfully completed without fluoroscopy, and without serious maternal or fetal complications. The procedure and ablation application times were 55.0±30.0 min and 394±338 s, respectively. In one patient second procedure for idiopathic ventricular arrhythmia was postponed after delivery. Conclusion Implementation of pregnancy heart team and a standard fluoroless protocol for CA in daily electrophysiological practice allowed an early, safe, and effective CA of maternal supraventricular tachycardia and idiopathic ventricular arrhythmias in pregnancy. Funding Acknowledgement Type of funding source: None </jats:sec

Non-invasive and invasive autonomic tests to facilitate cardioneuroablation and complex indications for transcutaneous lead extraction and discontinuation of permanent pacing

Abstract Funding Acknowledgements Type of funding sources: None. OnBehalf Rare-A-Care registry Background  Extracardiac vagal nerve stimulation (ECANS) and cardioneuroablation (CNA) are promising methods to cure vagally mediated bradycardia and validate indications for permanent pacing for sinus node dysfunction (SND), atrioventricular blocks (AVB), tachycardia-bradycardia syndrome (TBS) and cardio-inhibitory or mixed reflex syncope (VVS). There are limited information on clinical utility of those procedures in validation of indication for continuation of permanent pacing (PM) and transcutaneous lead extraction (TLE). Methods  Data were collected from prospective multicentre registry of CNA facilitated by interdisciplinary consultations, state-of-art autonomic tests, atropine/propranolol tests, electrophysiologic study as well as ECANS. Share-decision making were used by EP-HEART-TEAM to developed patient-oriented therapy. Results  Between June 2018-Jan 2021 the first 102 consecutive patients underwent interdisciplinary approach before invasive EPS and/or invasive ECANS, to consider biatrial, binodal CNA, if possible to cure functional bradycardia. Eleven (10%) patients had implanted permanent PM"s due to SND/AVB/TBS/CI-VVS and were considered for TLE. In 2 out of 11 cases CNA was not performed due to: 1) structural advanced 2nd and 3rd degree AVB with indication for TLE and permanent HBP (no.1), 2) incidental severely symptomatic persistent 3rd degree AVB more than 15 year ago without any further bradycardia episodes (only TLE, no.2). In further 9 of 11 cases with PM CNA was performed, however TLE was not attempted in 2 patients [(SND + PVC ablation + indication for beta-blocker therapy due to IHD in older male. TLE had not yet been attempted to confirm long-term success therapy by patient and/or physician (no.3); two periprocedural successful CNA resulted in disappearance of CI reflex however  despite pacing syncopal events persist due to mixed etiology (no.4)]. In further 7/11 cases TLE-s were performed. Three cases had TLE prior to CNA [VVS-CI + advanced functional AVB - prior 3 pacemaker reimplantations and further "rescue" CNA, (no.5); CI-VVS + pacemaker infection (no.6); TLE of PM + TBS no.7]. Finally, in 4 cases TLE was recommended after CNA [CI-VVS (no.8, no.9 and no.10); mixed etiology: TBS + VVS-CI + intermittent, recurrent pericardial efffusion due to lead perforation, PM syndrome, (no. 11)].  Conclusions  Interdisciplinary and comprehensive autonomic approach with ECANS and CNA enable EP-HEART-TEAM to offer patient-oriented therapy with a complex clinical scenarios before final decision about TLE and discontinuation of permanent pacing therapy. </jats:sec