Aircraft noise exposure induces pro-inflammatory vascular conditioning and amplifies vascular dysfunction and impairment of cardiac function after myocardial infarction

AIMS

Traffic noise may play an important role in the development and deterioration of ischemic heart disease. Thus, we sought to determine the mechanisms of cardiovascular dysfunction and inflammation induced by aircraft noise in a mouse model of myocardial infarction (MI) and in humans with incident MI.

METHODS AND RESULTS

C57BL/6J mice were exposed to noise alone (average sound pressure level 72 dB; peak level 85 dB) up to 4d, resulting in pro-inflammatory aortic gene expression in the myeloid cell adhesion/diapedesis pathways. Noise alone promoted adhesion and infiltration of inflammatory myeloid cells in vascular/cardiac tissue, paralleled by an increased percentage of leukocytes with a pro-inflammatory, reactive oxygen species (ROS)-producing phenotype and augmented expression of Nox-2/phospho-NFκB in peripheral blood. Ligation of the LAD resulted in worsening of cardiac function, pronounced cardiac infiltration of CD11b+ myeloid cells and Ly6Chigh monocytes and induction of interleukin (IL) 6, IL-1β, CCL-2 and Nox-2, being aggravated by noise exposure prior to MI. MI induced stronger endothelial dysfunction and more pronounced increases in vascular ROS in animals preconditioned with noise. Participants of the population-based Gutenberg Health Cohort Study (median follow-up:11.4y) with incident MI revealed elevated CRP at baseline and worse LVEF after MI in case of a history of noise exposure and subsequent annoyance development.

CONCLUSION

Aircraft noise exposure before MI substantially amplifies subsequent cardiovascular inflammation and aggravates ischemic heart failure, facilitated by a pro-inflammatory vascular conditioning. Our translational results suggest, that measures to reduce environmental noise exposure will be helpful in improving clinical outcome of subjects with MI.

Use of Elastic Stain Technique to Detect Histologically Occult Vascular Invasion in Resected Colorectal Carcinomas at Danbury Hospital

Introduction/Objective

Colorectal carcinoma (CRC) represents a leading cause of cancer related death in the western world and is by far the most common malignancy of the gastrointestinal tract. Vascular invasion (VI), in particular extramural VI by tumor is recognized as a feature of colorectal cancer progression, and the latter is an independent prognostic indicator of disease recurrence and survival in colorectal carcinoma. The purpose of this study is to detect VI in resected colorectal tumor samples and compare sensitivity of elastic staining to routine H&E staining at Danbury Hospital.

Methods/Case Report

A total of 50 colorectal cancer specimens from segmental colon resection or endoscopic polypectomy performed at Danbury Hospital over a 3-year period were included. Histologic sections of each tumor were assessed for the presence of VI by routine H&E staining. Superficial recuts of each tumor were subjected to elastic Von Giesen staining and reassessed for the presence of vascular invasion. Sensitivity of routine H&E staining for the detection of VI was calculated with elastic stain serving as the “gold standard”.

Results (if a Case Study enter NA)

In this study, VI by carcinoma was identified by H&E stain and/or elastic stain in 17 (34%) out of 50 cases. H&E stain and elastic stain detected VI in 12 (24%) and 16 (32%) out of 50 cases, respectively. There was a single case for which H&E stain showed vascular invasion that was not confirmed by elastic stain, representing a false negative for the H&E technique. Elastic staining detected VI in 5 cases for which the corresponding H&E stain was falsely negative for VI. Overall, vascular invasion status (absent or present) was concordant in 44 (88 %) of the 50 cases. With elastic stain deemed the “gold standard” for VI detection, the sensitivity, specificity, negative predictive value, and positive predictive value of H&E stain were found to be 68.7%, 97.0%, 86.8%, and 91.6%, respectively.

Conclusion

Although H & E staining of colorectal carcinoma tissue sections have a very good specificity and positive predictive value for the detection of VI, this technique suffers from a suboptimal sensitivity. For these reasons, we agree with previously published literature reports that the use of elastic stain as a supplement to H & E staining should be strongly considered for the proper evaluation and prognostication of colorectal carcinoma specimens.

Behaviour change during dietary Type 2 diabetes remission: a longitudinal qualitative evaluation of an intervention using a very low energy diet

AIM

To understand the process of behaviour change through the experiences of people with Type 2 diabetes engaged in an 8-month diabetes remission intervention including a 2-month weight loss phase with the use of a very low energy diet (VLED), and a 6-month, structured weight maintenance phase.

METHODS

Data were collected in three semi-structured interviews at baseline, week 8 (end of the weight loss phase), and month 8 (end of the weight maintenance phase). Longitudinal inductive thematic analysis was used to analyse participants' narratives and identify change over time.

RESULTS

Eleven of 18 participants completed all three interviews. The following themes of change were identified in their narratives: (1) 'Building behavioural autonomy' as a process of growing confidence to engage in health behaviours that are independent of those of other people; (2) 'Behavioural contagion' describing how one's new health behaviours tend to affect those of other people; (3) 'From rigid to flexible restraint', reflecting the changes in attitudes and behaviours required for a successful adaptation from weight loss to weight maintenance; and (4) 'Shift in identity', representing changes in the participants' perceptions of themselves.

CONCLUSIONS

This longitudinal qualitative study provided new insights into how behaviour change is experienced by people with Type 2 diabetes engaged on a weight management intervention using VLED, contributing to theoretical and practical understanding of weight management behaviours. The themes identify potential areas in which individuals can be supported in achieving dietary diabetes remission and long-term maintenance of weight loss.

P4478Noise pollution exacerbates the development of arterial hypertension via additive oxidative stress and impairment of NO signaling

Background

Environmental noise pollution has been identified as a cardiovascular risk and is characterized by moderate hypertension, endothelial dysfunction, increased oxidative stress, and inflammation. We have gained insights into the mechanism by which these consequences occur by exposing mice lacking the critical NADPH oxidase subunit gp91phox to aircraft noise. Mice were protected from the effects of aircraft noise exposure. NADPH oxidase is believed to be the mediator by which angiotensin II increases oxidative stress, making investigation into the additive effect of noise and hypertension an important subject in modern cardiovascular health research.

Methods and results

C57Bl/6J mice were implanted with subcutaneous osmotic mini-pumps, delivering a moderate dose of 0.5mg/kg/d of angiotensin II for 7 days. Immediately following the implantation, half the mice were exposed to aircraft noise for 7 days at a maximum sound pressure level of 85 dB(A) and a mean sound pressure level of 72 dB(A), a level at which hearing loss does not occur*. Non-invasive blood pressure measurements revealed an additive increase in blood pressure in noise-exposed hypertensive mice. Following sacrifice, endothelial dysfunction was evaluated through isometric tension recordings of 3mm aortic ring segments. These recordings support the blood pressure measurements and indicate a more serious impairment in acetylcholine-induced vasorelaxation in hypertensive mice exposed to noise than the hypertensive or noise only controls. Whole blood stimulated with phorbol 12,13-dibutyrate (PDBu) or zymosan A showed an additive increase in oxidative burst in in noise-exposed hypertensive mice. Dihydroethidium (DHE) staining was used to assess the presence of vascular and cerebral oxidative stress, showing similar additive effects in mice with hypertension plus noise exposure. High performance liquid chromatography (HPLC) measurement of 2-hydroxyethidium further confirmed additive increase of oxidative stress in the aorta and brain. Western blot analysis of aortic tissue revealed highest levels of gp91phox in mice with hypertension plus noise exposure and indicated a decrease in the ratio of P-eNOSSer1177:eNOS as well as a decrease in the ratio of eNOS dimer:monomer, exposing eNOS uncoupling as a potential pathomechanism for endothelial dysfunction and gp91phox as a source for the oxidative stress.Ongoing immunohistochemical and flow cytometric investigations will characterize the role of immune cells in these adverse effects.

Conclusion

Herein, we present novel data demonstrating additive noise-induced cardiovascular consequences on developing hypertension. Noise has previously been established as a cardiovascular risk factor, but the effects have not been determined in pre-existing or developing cardiovascular disease. Our results show a cumulative effect between noise exposure and hypertension and forge an important link between environmental stressors and cardiovascular health.

Acknowledgement/Funding

Boehringer Ingelheim Foundation

P4476Cardiovascular benefits of GLP-1 (liraglutide) treatment in experimental arterial hypertension are mediated by the endothelial GLP-1 receptor

Objective

The LEADER trial demonstrated that glucagon-like peptide-1 (GLP-1) analogs like Liraglutide (Lira) reduce the risk of cardiovascular events in T2DM, an effect beyond glycemic control. A detailed evaluation of the precise mechanisms underlying the cardiovascular protective effects of GLP-1 has been hampered by the fact that the GLP-1 receptor is expressed on different cell types in the vasculature including platelets, neuronal, endothelial and inflammatory cells. We used endothelial and myeloid cell-specific knockout mice of the GLP-1 receptor (GLP-1r) in an angiotensin-II (ATII)-induced model of hypertension. The aim of the recent study was to investigate the cardioprotective effects of GLP-1 in ATII-induced arterial hypertension and to characterize the cell-specific contribution of GLP-1r signaling.

Methods

Arterial hypertension was induced by s.c. ATII administration (0.5mg/kg/d; 7 days) in WT (C57/BL6J) as well as endothelial and myeloid cell-specific GLP-1r knockout mice (Cdh5crexGLP-1rfl/fl and LysMcrexGLP-1rfl/fl mice). Animals were treated with Lira (2x30μg/d; 7 days). Blood pressure was measured by tail-cuff. Vascular function was tested by isometric tension recording. Aortic and cardiac tissue was used for Western blotting, qRT-PCR, FACS, IHC and HPLC to determine the extent of inflammation, oxidative stress and fibrosis. ELISA was used to determine GLP-1 and insulin levels in plasma.

Results

Endogenous GLP-1 (7–36 and 9–36) was reduced in hypertensive animals. Lira ameliorated blood pressure and improved endothelial dysfunction, vascular oxidative stress and inflammation caused by ATII, in both WT and myeloid cell-specific GLP-1r knockout mice. Hypertension led to infiltration of inflammatory monocytes (Ly6G-Ly6Chigh) and neutrophils (Ly6G+Ly6C+) into the vascular wall, which was prevented by Lira. In accordance, Lira suppressed vascular oxidative stress and mRNA expression of iNOS, CD11b and Nox2. Endothelial NO synthase (eNOS) was S-glutathionylated with ATII treatment indicating uncoupled eNOS. Thus, aortic NO levels were reduced, all of which was restored by Lira. Furthermore, vascular fibrosis and cardiac hypertrophy were tremendously reduced by GLP-1. Interestingly, all of these beneficial cardiovascular effects of GLP-1 were abolished in endothelial cell-specific GLP-1r knockout mice.

Conclusion

We show that Lira reduces blood pressure and improves vascular function, fibrosis and cardiac hypertrophy in experimental arterial hypertension in mice. Mechanistically, Lira prevents the infiltration of inflammatory cells to the vascular wall, leading to reduced oxidative stress and improved NO bioavailability. Beneficial effects of GLP-1 are mediated by the GLP-1r expressed on endothelial and not myeloid cells. With the present study we provide a mechanistic approach to explain the cardioprotective effects of GLP-1 analogs like Lira, for which the endothelial GLP-1 receptor is indispensable.

Acknowledgement/Funding

Deutsche Forschungsgesellschaft (DFG), Bundesministerium für Bildung und Forschung (BMBF)

P717Glucagon-like peptide 1 (GLP-1) improves endothelial dysfunction and vascular inflammation in polymicrobial sepsis induced by cecal ligation and puncture (CLP)

Objective

Sepsis causes severe hypotension, accompanied by high mortality in the setting of septic shock. LEADER, SUSTAIN-6 and other clinical trials revealed cardioprotective and anti-inflammatory properties of GLP-1 analogs like Liraglutide (Lira). We already demonstrated improved survival by amelioration of disseminated intravasal coagulation (DIC) in lipopolysaccharide (LPS)-induced endotoxemia by inhibition of the GLP-1 degrading enzyme dipeptidylpeptidase-4 (DPP-4). With the present study we aim to investigate the mechanism of protective effects of the GLP-1 analog Lira and the DPP4 inhibitor Linagliptin (Lina) in the clinically relevant sepsis model cecal ligation and puncture (CLP).

Methods

C57/BL6j and endothelial cell-specific GLP-1 receptor knockout mice (Cdh5crexGLP-1rfl/flmice) were used and sepsis was induced by cecal ligation and puncture (CLP). DPP4 inhibitor (Lina, 5mg/kg/d; 3 days) and GLP-1 analog (Lira, 200μg/kg/d; 3 days) were applied subcutaneously. Aortic vascular function was tested by isometric tension recording. Aorta and heart tissue was used for Western blotting, dot blot and qRT-PCR. Endogenous GLP-1 (7–36 and 9–36) and insulin was determined by ELISA. Blood samples were collected for examination of cell count, oxidative stress and glucose levels.

Results

Body temperature was increased by CLP and normalized by Lina and Lira. Sham- and Lira- but not Lina-treated septic mice showed low blood glucose levels compared to healthy controls. Acetylcholine-induced (endothelium-dependent) vascular relaxation in aorta was impaired by CLP. This was accompanied by vascular inflammation and elevation of IL-6, iNOS, ICAM-1, and TNF-alpha mRNA levels in aortic tissue. Vascular, cardiac and whole blood oxidative stress were increased by CLP. Furthermore, we detected higher levels of IL-6, 3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-NHE) in plasma of CLP animals. Lina and Lira reduced oxidative stress and vascular inflammation, which was accompanied by improved endothelial function. In addition, CLP treatment in endothelial specific knockout mice of the GLP-1r strongly induced mortality compared to WT mice, with the effect being strongest in the Lira-treated group.

Conclusion

The present study demonstrates that Lina (DPP4 inhibitor) and the GLP-1 analog Lira ameliorate sepsis-induced endothelial dysfunction by reduction of vascular inflammation and oxidative stress. Clinical trials like LEADER and SUSTAIN-6 proved that GLP-1 analogs like Lira have cardioprotective effects in T2DM patients. The present study, performed in a clinically relevant model of polymicrobial sepsis, reveals that the known cardioprotective effects of GLP-1 might be translated to other diseases which affect the cardiovascular system like sepsis, underlining the potent anti-inflammatory effects of GLP-1 analogs.

Acceptability of a very-low-energy diet in Type 2 diabetes: patient experiences and behaviour regulation

AIMS

To evaluate the acceptability of an 8-week very-low-energy diet for remission of Type 2 diabetes, and to identify barriers and facilitators of adherence and behaviour-regulation strategies used by participants in the Counterbalance study.

METHODS

Eighteen of 30 participants in the Counterbalance study (ISRCTN88634530) took part in semi-structured interviews. Of these, 15 participants were interviewed before and after the 8-week very-low-energy diet intervention. Thematic analysis was used to analyse the narratives.

RESULTS

The prospect of diabetes remission, considerable weight loss, and long-term health improvement provided participants with substantial initial motivation. This motivation was sustained through the experience of rapid weight loss, improvements in blood glucose levels, social support and increased physical and psychological well-being. Overall, adherence to the very-low-energy diet for 8 weeks was perceived as much easier than anticipated, but required personal effort. Participants addressed challenges by removing food from the environment, planning, avoidance of tempting situations or places, and self-distraction. Weight loss and improvements in blood glucose levels lead to a sense of achievement and improvements in physical and psychological wellbeing.

CONCLUSIONS

Dietary treatment for reversal of Type 2 diabetes is acceptable and feasible in motivated participants, and the process is perceived as highly gratifying. Research outside of controlled trial settings is needed to gauge the generalisability of these findings.

Calorie restriction and not glucagon-like peptide-1 explains the acute improvement in glucose control after gastric bypass in Type 2 diabetes

AIMS

To compare directly the impact of glucagon-like peptide-1 secretion on glucose metabolism in individuals with Type 2 diabetes listed for Roux-en-Y gastric bypass surgery, randomized to be studied before and 7 days after undergoing Roux-en-Y gastric bypass or after following a very-low-calorie diet.

METHODS

A semi-solid meal test was used to investigate glucose, insulin and glucagon-like peptide-1 response. Insulin secretion in response to intravenous glucose and arginine stimulus was measured. Hepatic and pancreatic fat content was quantified using magnetic resonance imaging.

RESULTS

The decrease in fat mass was almost identical in the Roux-en-Y gastric bypass and the very-low-calorie diet groups (3.0±0.3 and 3.0±0.7kg). The early rise in plasma glucose level and in acute insulin secretion were greater after Roux-en-Y gastric bypass than after a very-low-calorie diet; however, the early rise in glucagon-like peptide-1 was disproportionately greater (sevenfold) after Roux-en-Y gastric bypass than after a very-low-calorie diet. This did not translate into a greater improvement in fasting glucose level or area under the curve for glucose. The reduction in liver fat was greater after Roux-en-Y gastric bypass (29.8±3.7 vs 18.6±4.0%) and the relationships between weight loss and reduction in liver fat differed between the Roux-en-Y gastric bypass group and the very-low-calorie diet group.

CONCLUSIONS

This study shows that gastroenterostomy increases the rate of nutrient absorption, bringing about a commensurately rapid rise in insulin level; however, there was no association with the large post-meal rise in glucagon-like peptide-1, and post-meal glucose homeostasis was similar in the Roux-en-Y gastric bypass and very-low-calorie diet groups. (Clinical trials registry number: ISRCTN11969319.).

Restoring normoglycaemia by use of a very low calorie diet in long- and short-duration Type 2 diabetes

AIMS

To establish whether an 8-week very-low-calorie diet could improve glycaemic control in Type 2 diabetes of long duration.

METHODS

A total of 29 people with Type 2 diabetes [short-duration group (diabetes duration < 4 years), n = 15; long-duration group (diabetes duration > 8 years), n = 14] completed an 8-week very-low-calorie diet, with assessments of fasting anthropometry, blood tests and blood pressure at baseline and weeks 1, 4 and 8 of the diet.

RESULTS

Similar weight loss was achieved in the short- and long-duration groups (14.8 ± 0.8% and 14.4 ± 0.7% respectively; P = 0.662). The glucose response to acute calorie restriction was heterogeneous in the long-duration group with some responding similarly to those in the short-duration group, some responding, but only slowly, and others not responding at all. Overall, HbA1c concentration in the short- vs. long-duration groups fell to 44 ± 2 vs. 64 ± 6 mmol/l (6.2 ± 0.2 vs. 8.0 ± 0.5%; P = 0.002). Fasting plasma glucose levels decreased to 5.8 ± 0.2 vs. 8.4 ± 1.1 mmol/l (P = 0.024) respectively. A total of 87% of the short-duration group and 50% of the long-duration group achieved non-diabetic fasting plasma glucose levels at week 8. Clinically significant improvements in blood pressure and lipid profile were seen regardless of diabetes duration.

CONCLUSION

In people with Type 2 diabetes of > 8 years' duration, a therapeutic trial of a very-low-calorie diet may be undertaken with a 50% chance of achieving non-diabetic fasting glucose levels off all antidiabetic therapies.

Reversal of Type 2 diabetes after bariatric surgery is determined by the degree of achieved weight loss in both short- and long-duration diabetes

AIM

To define the impact of duration of diabetes and extent of weight loss on the reversibility of Type 2 diabetes after bariatric surgery.

METHODS

Complete data were collated from 89 individuals with Type 2 diabetes mellitus undergoing any bariatric surgical procedure in a specialist bariatric centre. People with a preoperative HbA1c < 43 mmol/mol (6.1%) were excluded. Diabetes duration was defined as: short, < 4 years; medium, 4-8 years; and long, > 8 years.

RESULTS

An HbA1c of <43 mmol/mol (6.1%) was achieved by 62% of patients in the short-duration group and 26% of patients in the long-duration group. Normoglycaemia was rarely achieved in the long-duration group if weight loss was < 25 kg. In the whole cohort there was a clear relationship of greater weight loss with lower HbA1c levels (Rs = -0.53; P < 0.0001).

CONCLUSIONS

The study shows that the degree of achieved weight loss is the major determinant of return to normal blood glucose levels after bariatric surgery. Normoglycaemia can be achieved in long-duration Type 2 diabetes, but a greater degree of weight loss is required than for short-duration diabetes.

Population response to information on reversibility of Type 2 diabetes

AIMS

Following publication of the Counterpoint Study (on the reversibility of Type 2 diabetes using a very low energy diet), the extent of public interest prompted the authors to make available, on a website, general information about reversing diabetes. Shortly thereafter, individuals began to feed back their personal experiences of attempting to reverse their diabetes. We have collated this information on the effects of energy restriction in motivated individuals with Type 2 diabetes that has been achieved outside a research setting.

METHODS

Emails, letters and telephone communications received between July 2011 and September 2012 were evaluated (n = 77: 66 men, 11 women). Median diabetes duration was 5.5 years (3 months-28 years). Reversal of diabetes was defined as achieving fasting capillary blood glucose < 6.1 mmol/l and/or, if available, HbA1c less than 43 mmol/mol (6.1%) off treatment.

RESULTS

Self-reported weight fell from 96.7 ± 17.5 kg at baseline to 81.9 ± 14.8 kg after weight loss (P < 0.001). Self-reported fasting blood glucose levels fell from 8.3 mmol/l (5.9-33.0) to 5.5 mmol/l (4.0-10.0) after the weight loss period (P < 0.001). Diabetes reversal was considered to have occurred in 61% of the population. Reversal of diabetes was observed in 80, 63 and 53% of those with > 20, 10-20 and < 10 kg weight loss, respectively. There was a significant correlation between degree of weight loss and reported fasting glucose levels (Rs -0.38, P = 0.006). Reversal rates according to diabetes duration were: short (< 4 years) = 73%, medium (4-8 years) = 56% and long (> 8 years) = 43%.

CONCLUSION

These data demonstrate that intentional weight loss achieved at home by health-motivated individuals can reverse Type 2 diabetes. Diabetes reversal should be a goal in the management of Type 2 diabetes.

Type 2 diabetes, bariatric surgery and the risk of subsequent gestational diabetes

Women with pre-existing abnormal glucose regulation are certain to develop gestational diabetes in pregnancy and pre-gestational type 2 diabetes will become more difficult to control. However, an increasing number of women with type 2 diabetes have had bariatric surgery. In this group, the effect of pregnancy on glucose metabolism is unknown. We report two women with type 2 diabetes who underwent laparoscopic gastric bypass surgery with normalization of plasma glucose levels. During subsequent pregnancy, maternal blood glucose levels remained completely normal throughout. This is remarkable given the predisposition to abnormal glucose tolerance and the ongoing obesity, in the face of the insulin resistance of pregnancy. Women with prior type 2 diabetes reversed by gastric bypass surgery are not at high risk for gestational diabetes.