Optimising triage of urgent referrals for suspected IBD: results from the Birmingham IBD inception study

Objective: Diagnostic delays in inflammatory bowel disease (IBD) result in adverse outcomes. We report a bespoke diagnostic pathway to assess how best to combine clinical history and faecal calprotectin (FCP) for early diagnosis and efficient resource utilisation. Methods: A rapid-access pathway was implemented for suspected IBD patients referred outside urgent ‘two-week wait’ criteria. Patients were triaged using symptoms and FCP. A 13-point symptom history was taken prediagnosis and clinical indices, including repeat FCP, collected prospectively. Results: Of 767 patients (January 2021–August 2023), 423 were diagnosed with IBD (208 Crohn’s disease (CD), 215 ulcerative colitis (UC)). Most common symptoms in CD were abdominal pain (84%), looser stools (84%) and fatigue (79%) and in UC per-rectal bleeding (94%), urgency (82%) and looser stools (81%). Strongest IBD predictors were blood mixed with stools (CD OR 4.38; 95% CI 2.40–7.98, UC OR 33.68; 15.47–73.33) and weight loss (CD OR 3.39; 2.14–5.38, UC OR 2.33; 1.37–4.00). Repeat FCP testing showed reduction from baseline in non-IBD. Both measurements >100 µg/g (area under the curve (AUC) 0.800) and >200 µg/g (AUC 0.834) collectively predicted IBD. However, a second value ≥220 µg/g considered alone, regardless of the first result, was more accurate (Youden’s index 0.735, AUC 0.923). Modelling symptoms with FCP increased AUC to 0.947. Conclusion: Serial FCP measurement prevents unnecessary colonoscopy. Two FCPs >200 µg/g could stream patients direct to colonoscopy, with two >100 µg/g prompting clinic review. A second result ≥220 µg/g was more accurate than dual-result thresholds. Coupling home FCP testing with key symptoms may form the basis of effective self-referral pathways

PITX2 Modulates Atrial Membrane Potential and the Antiarrhythmic Effects of Sodium-Channel Blockers.

BACKGROUND: Antiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). OBJECTIVES: After determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs. METHODS: LA PITX2 messenger ribonucleic acid (mRNA) levels were measured in 95 patients undergoing thoracoscopic AF ablation. The effects of flecainide, a sodium (Na(+))-channel blocker, and d,l-sotalol, a potassium channel blocker, were studied in littermate mice with normal and reduced Pitx2c mRNA by electrophysiological study, optical mapping, and patch clamp studies. PITX2-dependent mechanisms of antiarrhythmic drug action were studied in human embryonic kidney (HEK) cells expressing human Na channels and by modeling human action potentials. RESULTS: Flecainide 1 μmol/l was more effective in suppressing atrial arrhythmias in atria with reduced Pitx2c mRNA levels (Pitx2c(+/-)). Resting membrane potential was more depolarized in Pitx2c(+/-) atria, and TWIK-related acid-sensitive K(+) channel 2 (TASK-2) gene and protein expression were decreased. This resulted in enhanced post-repolarization refractoriness and more effective Na-channel inhibition. Defined holding potentials eliminated differences in flecainide's effects between wild-type and Pitx2c(+/-) atrial cardiomyocytes. More positive holding potentials replicated the increased effectiveness of flecainide in blocking human Nav1.5 channels in HEK293 cells. Computer modeling reproduced an enhanced effectiveness of Na-channel block when resting membrane potential was slightly depolarized. CONCLUSIONS: PITX2 mRNA modulates atrial resting membrane potential and thereby alters the effectiveness of Na-channel blockers. PITX2 and ion channels regulating the resting membrane potential may provide novel targets for antiarrhythmic drug development and companion therapeutics in AF

A Regional Reduction in Ito and IKACh in the Murine Posterior Left Atrial Myocardium Is Associated with Action Potential Prolongation and Increased Ectopic Activity.

BACKGROUND: The left atrial posterior wall (LAPW) is potentially an important area for the development and maintenance of atrial fibrillation. We assessed whether there are regional electrical differences throughout the murine left atrial myocardium that could underlie regional differences in arrhythmia susceptibility. METHODS: We used high-resolution optical mapping and sharp microelectrode recordings to quantify regional differences in electrical activation and repolarisation within the intact, superfused murine left atrium and quantified regional ion channel mRNA expression by Taqman Low Density Array. We also performed selected cellular electrophysiology experiments to validate regional differences in ion channel function. RESULTS: Spontaneous ectopic activity was observed during sustained 1Hz pacing in 10/19 intact LA and this was abolished following resection of LAPW (0/19 resected LA, P<0.001). The source of the ectopic activity was the LAPW myocardium, distinct from the pulmonary vein sleeve and LAA, determined by optical mapping. Overall, LAPW action potentials (APs) were ca. 40% longer than the LAA and this region displayed more APD heterogeneity. mRNA expression of Kcna4, Kcnj3 and Kcnj5 was lower in the LAPW myocardium than in the LAA. Cardiomyocytes isolated from the LAPW had decreased Ito and a reduced IKACh current density at both positive and negative test potentials. CONCLUSIONS: The murine LAPW myocardium has a different electrical phenotype and ion channel mRNA expression profile compared with other regions of the LA, and this is associated with increased ectopic activity. If similar regional electrical differences are present in the human LA, then the LAPW may be a potential future target for treatment of atrial fibrillation

Changes to endothelial cell function induced by hydrogen peroxide : a model of cell senescence

Endothelial dysfunction is an early stage in atherosclerosis and is associated with oxidative stress, which occurs when reactive oxygen species are not fully compensated by cellular antioxidants. This study investigated the effects of hydrogen peroxide in a human endothelial cell model. EA.hy926 cells incubated for 1 hour at 37°C with increasing concentrations of hydrogen peroxide were investigated for DNA damage ('Comet' assay), changes in mitochondrial activity (MTT assay), apoptosis and necrosis (Annexin V assay), cell growth and senescence (changes in morphology, cell size, pH6 specific B-galactosidase (S-Gal) and telomere shortening). Changes in the expression of mRNA transcripts of thrombotic (tissue factor); fibrinolytic (tissue phasminogen activator and plasminogen activator inhibitor-1) and adhesion (ICAM-1) proteins were investigated using RT-PCR. Low (≤50muM) concentrations of hydrogen peroxide induced detectable, but reversible, DNA damage; which was accompanied only by a small decrease in mitochondrial activity. Intermediate levels of oxidative stress (<200muM H2O2) resulted in a dose-dependent effect on DNA damage and mitochondrial function. Exposure to hydrogen peroxide concentrations equal to or above 200muM caused immediate changes in a sub-set of the cells, including apoptosis (n=4). In the surviving cells proliferative ability was reduced, and senescent-like cells developed; indicated by an increase in S-Gal positive cells, a skewed increase in cell size and the appearance of 'giant' cells, but not by changes in telomere length. Tissue Factor and ICAM-1 mRNA levels increased with a corresponding increase in surface ICAM-1 protein expression, but there was no effect on either of the fibrinolytic factor transcripts (n=3). This study demonstrated that endothelial cells surviving an oxidative insult showed an altered phenotype becoming more adhesive and possibly more thrombogenic in parallel with the appearance of senescence. In vivo, these changes would accelerate the progression of atherosclerothrombosis and lead to an impaired ability to repair further injury to the endothelium

Omega-3 fatty acids and inflammation: novel interactions reveal a new step in neutrophil recruitment

Inflammation is a physiological response to tissue trauma or infection, but leukocytes, which are the effector cells of the inflammatory process, have powerful tissue remodelling capabilities. Thus, to ensure their precise localisation, passage of leukocytes from the blood into inflamed tissue is tightly regulated. Recruitment of blood borne neutrophils to the tissue stroma occurs during early inflammation. In this process, peptide agonists of the chemokine family are assumed to provide a chemotactic stimulus capable of supporting the migration of neutrophils across vascular endothelial cells, through the basement membrane of the vessel wall, and out into the tissue stroma. Here, we show that, although an initial chemokine stimulus is essential for the recruitment of flowing neutrophils by endothelial cells stimulated with the inflammatory cytokine tumour necrosis factor-?, transit of the endothelial monolayer is regulated by an additional and downstream stimulus. This signal is supplied by the metabolism of the omega-6-polyunsaturated fatty acid (n-6-PUFA), arachidonic acid, into the eicosanoid prostaglandin-D2 (PGD2) by cyclooxygenase (COX) enzymes. This new step in the neutrophil recruitment process was revealed when the dietary n-3-PUFA, eicosapentaenoic acid (EPA), was utilised as an alternative substrate for COX enzymes, leading to the generation of PGD3. This alternative series eicosanoid inhibited the migration of neutrophils across endothelial cells by antagonising the PGD2 receptor. Here, we describe a new step in the neutrophil recruitment process that relies upon a lipid-mediated signal to regulate the migration of neutrophils across endothelial cells. PGD2 signalling is subordinate to the chemokine-mediated activation of neutrophils, but without the sequential delivery of this signal, neutrophils fail to penetrate the endothelial cell monolayer. Importantly, the ability of the dietary n-3-PUFA, EPA, to inhibit this process not only revealed an unsuspected level of regulation in the migration of inflammatory leukocytes, it also contributes to our understanding of the interactions of this bioactive lipid with the inflammatory system. Moreover, it indicates the potential for novel therapeutics that target the inflammatory system with greater affinity and/or specificity than supplementing the diet with n-3-PUFA