Fifty-nine-year-old man with acute breathlessness and intermittent chest pain.

CLINICAL INTRODUCTION: A 59-year-old male patient presented with acute onset shortness of breath and intermittent chest pain. His medical history included squamous cell carcinoma of the left upper lobe of the lung (tumour, node, metastases T3N2M0), which was treated with radical radiotherapy with concurrent vinorelbine/cisplatin chemotherapy 6 months ago, hypertension, type 2 diabetes mellitus and hypercholesterolaemia. A 12-lead ECG on arrival is shown in figure 1A which has led to the patient undergoing emergency coronary angiography (figure 1B and online supplementary video). Admission blood tests revealed troponin T levels of 17 (0-14) ng/L, and an echocardiogram showed an akinetic basal septum and a hypokinetic basal-mid lateral anterior wall and apex. The next day, the patient underwent a functional and gadolinium-enhanced cardiovascular MRI (figure 1C,D).DC1SP110.1136/heartjnl-2018-314642.supp1Supplementary data QUESTION: What is the most likely cause of this patient's symptoms?ST-elevation myocardial infarction (STEMI) of the lateral wall.Compression of left circumflex artery due to metastatic disease.Acute pericarditis.Takotsubo syndrome. heartjnl;105/15/1189/F1F1F1Figure 1(A) Admission ECG, (B) coronary angiogram and (C,D) four-chamber view of cardiac MRI.

Mitochondrial uncoupling proteins regulate angiotensin-converting enzyme expression: crosstalk between cellular and endocrine metabolic regulators suggested by RNA interference and genetic studies.

Uncoupling proteins (UCPs) regulate mitochondrial function, and thus cellular metabolism. Angiotensin-converting enzyme (ACE) is the central component of endocrine and local tissue renin-angiotensin systems (RAS), which also regulate diverse aspects of whole-body metabolism and mitochondrial function (partly through altering mitochondrial UCP expression). We show that ACE expression also appears to be regulated by mitochondrial UCPs. In genetic analysis of two unrelated populations (healthy young UK men and Scandinavian diabetic patients) serum ACE (sACE) activity was significantly higher amongst UCP3-55C (rather than T) and UCP2 I (rather than D) allele carriers. RNA interference against UCP2 in human umbilical vein endothelial cells reduced UCP2 mRNA sixfold (P < 0·01) whilst increasing ACE expression within a physiological range (<1·8-fold at 48 h; P < 0·01). Our findings suggest novel hypotheses. Firstly, cellular feedback regulation may occur between UCPs and ACE. Secondly, cellular UCP regulation of sACE suggests a novel means of crosstalk between (and mutual regulation of) cellular and endocrine metabolism. This might partly explain the reduced risk of developing diabetes and metabolic syndrome with RAS antagonists and offer insight into the origins of cardiovascular disease in which UCPs and ACE both play a role.

Mitochondrial uncoupling proteins regulate angiotensin-converting enzyme expression: crosstalk between cellular and endocrine metabolic regulators suggested by RNA interference and genetic studies.

Uncoupling proteins (UCPs) regulate mitochondrial function, and thus cellular metabolism. Angiotensin-converting enzyme (ACE) is the central component of endocrine and local tissue renin-angiotensin systems (RAS), which also regulate diverse aspects of whole-body metabolism and mitochondrial function (partly through altering mitochondrial UCP expression). We show that ACE expression also appears to be regulated by mitochondrial UCPs. In genetic analysis of two unrelated populations (healthy young UK men and Scandinavian diabetic patients) serum ACE (sACE) activity was significantly higher amongst UCP3-55C (rather than T) and UCP2 I (rather than D) allele carriers. RNA interference against UCP2 in human umbilical vein endothelial cells reduced UCP2 mRNA sixfold (P < 0·01) whilst increasing ACE expression within a physiological range (<1·8-fold at 48 h; P < 0·01). Our findings suggest novel hypotheses. Firstly, cellular feedback regulation may occur between UCPs and ACE. Secondly, cellular UCP regulation of sACE suggests a novel means of crosstalk between (and mutual regulation of) cellular and endocrine metabolism. This might partly explain the reduced risk of developing diabetes and metabolic syndrome with RAS antagonists and offer insight into the origins of cardiovascular disease in which UCPs and ACE both play a role.

Duration of preceding hypertension is associated with prolonged length of ICU stay.

BACKGROUND: A substantial proportion of patients suffer prolonged length of intensive care unit stay (PLOS) or prolonged mechanical ventilation (PMV) following coronary artery bypass grafting (CABG). Identifying factors associated with PLOS and PMV would aid in patient risk stratification. We sought to identify the factors associated with PLOS and PMV following CABG. METHODS: Participants were patients undergoing first-time elective CABG. All were observed until discharge and clinical data were collected on a standardized proforma. PLOS and PMV were defined a priori as >2 days and >12 h respectively, based on centre norms. RESULTS: Of the 439 patients in the study, 105 (23.9%) had PLOS and 111 (25.2%) had PMV. Independent predictors of PMV were age, diabetes, previous myocardial infarction (MI), New York Heart Association (NYHA) class and statin use. The only independent predictor of PLOS was the duration of preceding hypertension. CONCLUSION: The factors associated with PMV and PLOS in our study are easily attainable, routine clinical details and may be built into bed management algorithms. Confirmation of the association of preceding hypertension and subsequent investigation of the possible mechanism mediating this association, is suggested.

Effect of erythropoietin as an adjunct to primary percutaneous coronary intervention: a randomised controlled clinical trial.

OBJECTIVE: The acute administration of high-dose erythropoietin (EPO) on reperfusing ischaemic myocardium has been reported to halve myocardial infarct (MI) size in preclinical studies, but its effect in ST elevation myocardial infarction patients undergoing primary percutaneous coronary intervention (PPCI) remains unknown. We investigated whether high-dose EPO administered as an adjunct to PPCI reduces MI size. DESIGN: Double-blinded, randomised, placebo-controlled. SETTING: Single tertiary cardiac centre. PATIENTS: Fifty-one ST elevation myocardial infarction patients undergoing PPCI. INTERVENTIONS: Patients were randomly assigned to receive either a single intravenous bolus of EPO (50,000 IU) prior to PPCI with a further bolus given 24 h later (n=26) or placebo (n=25). MAIN OUTCOME MEASURES: MI size measured by 24 h area under the curve troponin T and cardiac magnetic resonance imaging performed on day 2 and at 4 months. RESULTS: EPO treatment failed to reduce MI size (troponin T area under the curve: 114.6±78 µg/ml EPO vs 100.8±68 µg/ml placebo; infarct mass by cardiac magnetic resonance: 33±16 g EPO vs 25±16 g placebo; both p>0.05). Unexpectedly, EPO treatment doubled the incidence of microvascular obstruction (82% EPO vs 47% placebo; p=0.02) and significantly increased indexed left ventricular (LV) end-diastolic volumes (84±10 ml/m(2) EPO vs 73±13 ml/m(2) placebo; p=0.003), indexed LV end-systolic volumes (41±9 ml/m(2) EPO vs 35±11 ml/m(2) placebo; p=0.035) and indexed myocardial mass (89±16 g/m(2) EPO vs 79±11 g/m(2) placebo; p=0.03). At 4 months, there were no significant differences between groups. CONCLUSIONS: High-dose EPO administered as an adjunct to PPCI failed to reduce MI size. In fact, EPO treatment was associated with an increased incidence of microvascular obstruction, LV dilatation and increased LV mass. Clinical Trial Registration Information http://public.ukcrn.org.uk/search/StudyDetail.aspx?StudyID=4058 Unique Identifier=Study ID 4058.

Higher IL-6 levels but not IL6 -174G>C or -572G>C genotype are associated with post-operative complication following coronary artery bypass graft (CABG) surgery.

Large increases in inflammatory markers, particularly IL-6, occur after cardiac surgery. However, despite interventions to reduce the inflammatory response, great variability still remains which could in part be attributable to genetic predisposition. Since increased IL-6 levels following surgery are also associated with poorer outcome we sought to determine whether baseline and post-operative levels of Interleukin-6 (IL-6) and functional common variants of the Interleukin-6 (IL6) gene are associated with post-operative outcome following coronary artery bypass grafting (CABG). Caucasian patients undergoing first-time elective CABG were studied. IL-6 levels were measured pre-, 6h and 24h following surgery and genotypes for IL6 gene variants -174G>C and -572G>C were obtained. Clinical data was collected daily until patient discharge. Patient outcome was categorised as with (ICUC, n=177) and without (NICUC, n=189) a post-operative complication during the ICU period and with (POC, n=215) and without (NC, n=151) a post-operative complication during hospitalisation. IL-6 levels pre- and at 24h were greater in POC and ICUC than NC and NICUC, respectively. Pre- IL-6 levels independently predicted (for 1 standard deviation increase in log IL-6) POC (OR 1.4, 95% CI 1.1-1.7, p=0.008) and ICUC (OR 1.3, 95% CI 1.0-1.6, p=0.02) outcomes. Overall, the IL6-572G>C had an effect over time on IL-6 levels (p=0.04) and on IL-6 levels in NC (P=0.008) and NICUC (p=0.006). However, no associations were found with the IL6 -572G>C or -174G>C variants on IL-6 levels at individual time-points or by outcome group. Thus, in conclusion, elevated pre-operative IL-6 levels, but not IL6 gene variants predict poor patient outcome following CABG.

Association of serum interleukin-6 concentration with a functional IL6 -6331T>C polymorphism.

BACKGROUND: Interleukin-6 (IL-6) concentrations vary substantially among individuals. This study aimed to identify novel genetic markers to explain these differences. METHODS: We sequenced a region 6-kb upstream of the IL6 [interleukin 6 (interferon, beta 2)] transcription start site in a search for functional variants and detected 3 common variants: -6331T>C, -6101A>T, and -5617/-5616C/A>T/G. IL6 -6331T>C (C allele frequency, 0.20; 95% confidence interval, 0.16-0.24) showed strong negative linkage disequilibrium with -174G>C (D' = -0.97) and was studied further in 309 individuals who underwent coronary artery bypass grafting. RESULTS: Patients with the TT genotype had higher IL-6 concentrations 6 h after surgery than those with the CC genotype (mean, 199.4 ng/L vs 114.9 ng/L; P = 0.02). A similar association was seen in a cohort of 173 patients who underwent intensive periodontal therapy: Individuals with the CC genotype had significantly lower IL-6 concentrations 24 h after therapy than TT patients (mean, 0.78 ng/L vs 5.00 ng/L; P < 0.0001). A similar trend was observed in 203 healthy individuals from northern Europe (1.29 ng/L for the TT genotype vs 0.89 ng/L for the CC genotype; P = 0.07). Reporter assays that used a sequence flanking the -6331 single-nucleotide polymorphism spliced upstream to the IL-6 minimal promoter driving luciferase gene expression demonstrated a 1.3-fold increase in promoter activity (P < 0.01) for constructs containing -6331T. Electrophoretic mobility shift assays revealed enhanced binding of transcription factor Oct-1 to the T allele. CONCLUSIONS: IL6 -6331T is associated with increased IL-6 concentrations in an acute inflammatory state via a mechanism involving binding of the Oct-1 transcription factor. This finding may help resolve conflicting studies based on the IL6 -174G>C variant.

Free Interleukin (IL)-18 levels, and the impact of IL18 and IL18BP genetic variation, in CHD patients and healthy men.

OBJECTIVE: To investigate free interleukin-18 (fIL-18) levels, and variation within the IL-18 system genes, in heart surgery patients, and healthy men. METHODS AND RESULTS: fIL-18 was calculated from IL-18 and IL-18 binding protein (BP) levels, in 421 healthy men and 196 post-coronary artery bypass graft (CABG) patients. After surgery, fIL-18 peaked at 6 hours (from 117 to 331 pg/mL) but fell to below presurgery levels at 24 hours (99 pg/mL), because of changes in total IL-18 and IL-18BP. fIL-18 24 hours postsurgery was significantly higher in those who suffered a major complication after surgery (125 versus 80 pg/mL, P<0.01). Baseline total IL-18 was also higher in healthy men who went on to suffer an MI over 17 years of prospective study (276 versus 240 pg/mL, P=0.01). Tagging SNPs for IL18 (n=5) and IL18BP (n=3) were determined, in both studies the IL18 HapIII haplotype (frequency 30%) was associated with 36% lower baseline fIL-18 levels before surgery (P<0.01), and 7% lower in healthy men (P=0.04). The frequency of HapIII was lower in CABG patients than in healthy men (20.7 versus 29.8%, P<0.01). CONCLUSIONS: IL-18 levels, which are determined in part by variation in IL18, play a role in CHD development and postsurgery outcome.

A cortical potential reflecting cardiac function.

Emotional trauma and psychological stress can precipitate cardiac arrhythmia and sudden death through arrhythmogenic effects of efferent sympathetic drive. Patients with preexisting heart disease are particularly at risk. Moreover, generation of proarrhythmic activity patterns within cerebral autonomic centers may be amplified by afferent feedback from a dysfunctional myocardium. An electrocortical potential reflecting afferent cardiac information has been described, reflecting individual differences in interoceptive sensitivity (awareness of one's own heartbeats). To inform our understanding of mechanisms underlying arrhythmogenesis, we extended this approach, identifying electrocortical potentials corresponding to the cortical expression of afferent information about the integrity of myocardial function during stress. We measured changes in cardiac response simultaneously with electroencephalography in patients with established ventricular dysfunction. Experimentally induced mental stress enhanced cardiovascular indices of sympathetic activity (systolic blood pressure, heart rate, ventricular ejection fraction, and skin conductance) across all patients. However, the functional response of the myocardium varied; some patients increased, whereas others decreased, cardiac output during stress. Across patients, heartbeat-evoked potential amplitude at left temporal and lateral frontal electrode locations correlated with stress-induced changes in cardiac output, consistent with an afferent cortical representation of myocardial function during stress. Moreover, the amplitude of the heartbeat-evoked potential in the left temporal region reflected the proarrhythmic status of the heart (inhomogeneity of left ventricular repolarization). These observations delineate a cortical representation of cardiac function predictive of proarrhythmic abnormalities in cardiac repolarization. Our findings highlight the dynamic interaction of heart and brain in stress-induced cardiovascular morbidity.

Inflammatory response to coronary artery bypass surgery: does the heme-oxygenase-1 gene microsatellite polymorphism play a role?

BACKGROUND: Heme-oxygenase 1 (HO-1) is a rate-limiting enzyme in the degradation of heme to bilirubin, ferritin and carbon monoxide (CO) and may have significant anti-inflammatory function. The HO-1 gene promoter region shows microsatellite polymorphism with different (GT)n repeats, reported to differently induce gene expression, with the short allele associated with higher gene expression. We measured the acute inflammatory response using coronary artery bypass surgery (CABG) as a well-characterized and uniform stimulus and examined the correlation between levels of IL-6, C-reactive protein (CRP) and fibrinogen and their relationship to HO-1 genotype. METHODS: Two hundred and seventy-five consecutive patients undergoing CABG were genotyped for the HO-1 promoter polymorphism using PCR and automated DNA capillary sequencer. IL-6, CRP and fibrinogen were measured at baseline and 6, 24, 48, 72, 96 and 120 hours after CABG. RESULTS: Complete IL-6, CRP and fibrinogen measures were available in 220 patients. Before surgery IL-6 levels showed a strong correlation with CRP and fibrinogen (r = 0.48, P < 0.0001; r = 0.41, P < 0.0001 respectively), with a significant correlation between CRP and fibrinogen (r = 0.61, P < 0.0001). All three acute phase reactants showed a significant increase after CABG. After surgery, peak IL-6 was strongly correlated with peak CRP (r = 0.34, P = 0.0009) but not with peak fibrinogen (r = 0.15, P = 0.13), while peak CRP and peak fibrinogen were significantly correlated (r = 0.415, P < 0.0001). HO-1 allelic repeats ranged from 22-42, with (GT)25 and (GT)32 being the two most common alleles, and subsequently divided into three groups according to previous published work: <30 (GT)n were designated as S (short), 30-37 (GT)n as M (middle) and long repeats with >37 (GT)n as L (long); allele frequency 0.35, 0.58 and 0.07 respectively. Baseline CRP differed by genotype: those carrying at least one long allele having higher CRP than those with no long allele (3.76 +/- 0.79 vs. 2.07 +/- 0.17, P = 0.013). Conversely, those carrying at least one short allele had higher fibrinogen levels than those with no short allele (3.83 +/- 0.79 vs. 3.51 +/- 0.88, P = 0.006). CONCLUSIONS: There is a strong correlation between the measured acute phase reactants both at baseline and after the inflammatory response to CABG in patients with coronary disease. There was an association between the HO-1 microsatellite polymorphism and CRP and fibrinogen levels at baseline but there was no similar association following CABG. This may indicate that HO-1 is associated with chronic atherosclerotic inflammatory processes rather than acute.

Variation in the interleukin-6 gene is associated with impaired cognitive development in children born prematurely: a preliminary study.

The pro-inflammatory cytokine IL-6 may be neurocytopathogenic, and elevated levels are associated with impaired neurological outcome among children born prematurely. However, the precise mechanisms underlying this association remain unclear. The rare C (rather than G) variant at position -572 in the IL-6 gene is associated with an increased IL-6 synthetic response. If IL-6 mediates cerebral injury, we would anticipate the -572 C allele to be associated with impaired childhood development. We have examined this hypothesis, studying 113 Caucasian children born at < or =32 wk gestation. Cognitive and motor functions were assessed using the Griffiths Developmental Scales at 2 y and British Ability Scales (2nd Ed.) and the ABC Movement Score at 51/2 y. Performance (median, interquartile range) in all three scales was worse in the 10 carriers of the C allele than for those with GG genotype: Griffiths Developmental Quotient: C allele, 92.4 (89.9-96.6) versus CG 100.9 (96.7-104.8), p = 0.002; General Cognitive Ability: C allele, 88.0 (80.3-102.8) versus GG 103.0 (92.0-112.0), p = 0.037; Movement ABC score: C allele 8.3 (6.6-20.3) versus GG 4.0 (1.0-9.5), p = 0.081. The presence of the rare (> or =1) IL-6 -572 C-allele (CC+GC genotypes) is associated with impaired cognitive development among children born before 32 wk gestation. These data support a role for IL-6 in the genesis of neurologic impairment in such children.

Effect of enalapril and losartan on cytokines in patients with stable angina pectoris awaiting coronary artery bypass grafting and their interaction with polymorphisms in the interleukin-6 gene.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may have anti-inflammatory actions, an effect that could explain some of their beneficial effects on cardiovascular events in clinical trials. Coronary artery bypass grafting (CABG) is associated with a systemic inflammatory response and provides a convenient model to examine the effects of such agents. Genetic polymorphisms may be important in influencing the expression of cytokines, such as interleukin-6 (IL-6). We randomized men awaiting CABG to treatment with enalapril, losartan, or control for 2 months before surgery. Systemic IL-6, IL-8, IL-10, and IL-1 receptor agonists were measured before and after surgery, and genotypes for the -174 G/C and -572 G/C IL-6 gene polymorphisms were determined. Total release of the IL-1 receptor agonist was decreased 29% by enalapril and 31% by losartan (adjusted p = 0.041). IL-6 was decreased 17% by enalapril and 20% by losartan. Subjects possessing the -174 GG genotype produced 20% more IL-6 (adjusted p = 0.029). In these high producers of IL-6, release of IL-6 was decreased 51% by enalapril (adjusted p = 0.001) and 32% by losartan (adjusted p = 0.068). Release of IL-10 was nonsignificantly decreased 26% by enalapril and 21% by losartan, whereas IL-8 was not detected. In conclusion, enalapril and losartan significantly decreased release of the IL-1 receptor agonist after CABG. Enalapril produced a highly significant decrease of 51% in the release of IL-6 in patients identified as high producers of IL-6 by the -174 G/C polymorphism, whereas losartan has a similar but less marked effect. The production of IL-6 in this setting is influenced by the -174 G/C polymorphism.

Analysis of common IL-6 promoter SNP variants and the AnTn tract in humans and primates and effects on plasma IL-6 levels following coronary artery bypass graft surgery.

Interleukin-6 (IL-6) is a pro-inflammatory cytokine and major mediator of the acute phase response. Single nucleotide polymorphisms within the 5' flanking region (-597G>A, -572G>C and -174G>C) have previously been associated with increased risk of coronary heart disease and influencing transcription of IL-6 both in vitro and in vivo. In addition to these, a polymorphic AnTn tract is also present in the promoter of IL-6. Analysis in five different primate species demonstrated a G allele at -597, -572 and -174 in all species. By contrast, the AnTn tract was polymorphic in at least three species, and was roughly conserved in overall length despite an increase in the relative proportion of A versus T in the evolution of the human sequence from that in the ancestor of the great apes. The effect of the AnTn polymorphism on IL-6 levels was examined following coronary artery bypass graft surgery (CABG), a known inflammatory stimulus for IL-6 production. One hundred and thirty-two patients undergoing CABG were genotyped for the AnTn tract by automated sequencing. Four alleles were identified: A8T12 (allele frequency 0.35, 95% CI 0.29-0.40); A9T11 (0.26, 0.21-0.31); A10T11 (0.21, 0.16-0.26); and A10T10 (0.18, 0.14-0.23). Isolation of the effect of different alleles of the AnTn tract on an identical haplotypic background for the other polymorphisms in the promoter showed that individuals homozygous for A9T11 had significantly higher post-operative IL-6 levels than A10T11 homozygotes (275 +/- 46 pg/ml versus 152 +/- 29; P=0.04). The effect of the A8T12 allele could not be determined separately due to strong allelic association with -174C. The conserved length of the AnTn tract and the association in vivo with IL-6 levels strongly suggest the functionality of the tract on IL-6 expression, independent of contributions from other polymorphic sites within the promoter.

Cortical bone resorption during exercise is interleukin-6 genotype-dependent.

The objective of this study was to examine the relationship between the interleukin-6 (IL-6) -174 G>C promoter polymorphism and exercise-induced femoral cortical bone resorption. Skeletal response to exercise was assessed in 130 male Caucasian army recruits. Five cross-sectional magnetic resonance images of the right femur were obtained before and after a 10-week period of basic physical training, and changes in cross-sectional cortical area were calculated. Recruits were genotyped for the -174 G>C IL-6 promoter polymorphism. Genotype frequencies (GG 36%, GC 47%, CC 22.17%) were in Hardy-Weinberg equilibrium. The mean percentage change in proximal femoral cross-sectional cortical area was strongly IL-6 genotype-dependent, with GG homozygotes losing 6.8 (3.82)% in cortical area, GC gaining+5.5 (4.88)% and CC gaining+17.3 (9.46)% (P=0.007 for linear trend). These changes persisted throughout the right femur and were significant in the femur as a whole (P=0.03). This study demonstrates an association between a functional polymorphism in the IL-6 gene and femoral cortical remodelling during strenuous physical exercise. Previous studies have suggested an important role for IL-6 in the regulation of bone mass in postmenopausal women, and in the invasion of bone by metastatic tumour deposits. These data extend these observations to the regulation of bone mass in healthy males, supporting a fundamental role for IL-6 in the regulation of bone mass and bone remodelling in humans.

Common promoter variant in cyclooxygenase-2 represses gene expression: evidence of role in acute-phase inflammatory response.

OBJECTIVE: Cyclooxygenase (COX)-2 is a key regulatory enzyme in the synthesis of prostanoids associated with trauma and inflammation. We investigated the COX-2 gene for functional variants that may influence susceptibility to disease. METHODS AND RESULTS: The promoter of COX-2 was screened for variants in healthy subjects by use of polymerase chain reaction-based methods. Promoter activity was investigated by using reporter expression experiments in human lung fibroblasts. Patients undergoing coronary artery bypass graft surgery, with measurements of plasma markers linked to COX-2 activity, were genotyped for association studies. A common COX-2 promoter variant, -765G>C, was found and shown to be carried by >25% of a group of healthy UK subjects. The -765C allele had significantly lower promoter activity compared with -765G, basally (28+/-3% lower, P<0.005) and in serum-stimulated cells (31+/-2% lower, P<0.005). In patients subjected to coronary artery bypass graft surgery, the magnitude of rise in levels of C-reactive protein (CRP) was strongly genotype dependent. Compared with -765G homozygotes, patients carrying the -765C allele had significantly lower plasma CRP levels at 1 to 4 days after surgery (14% lower at the peak of CRP levels on day 3, P<0.05 for all time points). CONCLUSIONS: For several acute and chronic inflammatory diseases, -765G>C may influence the variability of response observed.

Severity of meningococcal disease in children and the angiotensin-converting enzyme insertion/deletion polymorphism.

Critical illness outcome may be causally related to inflammatory response severity. Given that tissue angiotensin-converting-enzyme (ACE) regulates such responses and that the deletion (D) [rather than insertion (I)] variant of the ACE gene is associated with higher tissue ACE levels, DD genotype might be associated with a poorer outcome in a uniform infectious disease state. Illness severity (Pediatric RIsk of Mortality score, the Glasgow Meningococcal Septicaemia Prognostic Score [GMSPS], and clinical course) was recorded for consecutive white patients with meningococcal disease (n = 110, 34 DD genotype, 61 male, aged 49.4 +/- 5.4 months) referred to the Royal Liverpool Children's Hospital, UK. Compared with children with > or = I allele, DD genotype was associated with 14% higher predicted risk of mortality (p = 0.038), higher GMSPS (DD 9.4 +/- 0.5, ID/II 7.7+/- 0.4 [mean +/- SEM], p = 0.013), greater prevalence of inotropic support (76% versus 55%, p = 0.03) and ventilation (82% versus 63%, p = 0.04), and longer Pediatric Intensive Care Unit (PICU) stay (5.8 versus 3.9, p = 0.02). DD genotype frequency was 6% (1 case) for the 18 children who did not require PICU care, 33% for the 84 PICU survivors, and 45% for those who died (p = 0.01). ACE DD is associated with increased illness severity in meningococcal disease.

Analysis of gene-environment interactions by "stressing-the-genotype" studies: the angiotensin converting enzyme and exercise-induced left ventricular hypertrophy as an example.

The human angiotensin converting enzyme (ACE) gene contains a length polymorphism consisting of the presence (insertion, I) or absence (deletion, D) of a 287 base pair "Alu" repeat sequence in intron 16, with the D allele being associated with higher ACE levels than the I allele in plasma and in tissues. We have carried out several studies to examine the relationship between this polymorphism and cardiovascular health, and have examined the hypothesis that if renin-angiotensin systems regulate left ventricular (LV) growth, individuals of DD genotype might show a greater hypertrophic response than those of II genotype. A strategy was used involving screening over 1200 male military recruits to select only subjects homozygous for the I or D allele for the expensive and time-consuming but extremely accurate method of LV mass determination by magnetic resonance imaging. LV dimensions and mass were compared at the start and end of a 10-week physical training period. LV mass increased with training by 8.4 g overall (p < 0.0001), but with DD men showing roughly 3 fold greater growth than II men (p < 0.001). When indexed to lean body mass, LV growth in II subjects was essentially negligible whilst remaining significant in DD subjects (-0.022 vs +0.131 g/kg respectively, p = 0.0009). Although the precise molecular mechanism of this effect remains to be elucidated it clearly demonstrates the importance of the ACE-renin-angiotensin system in determining LV dimensions in situations of high cardiac demand, which may also be important in pathology such as hypertension and heart failure. The use of these "stress-the-genotype" approaches to explore gene-environment interactions are likely to be the key to understanding the causes determining both coronary artery disease and other multi-factorial disorders.