Greater adherence to the Mediterranean Dietary Approaches to Stop Hypertension Intervention for Neurodegenerative Delay (MIND) diet is associated with lower risk of inflammatory bowel disease: a prospective cohort study.

Background: The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet is emerging as a promising candidate for preventive measures against inflammatory bowel disease (IBD), though there is currently no direct evidence from population-based studies. This study aims to bridge the gap in understanding of the association of the MIND diet with IBD risk. Methods: We utilized data from 187 490 participants in the UK Biobank who provided dietary information and were free of IBD at baseline. Dietary information was obtained using a validated web-based 24-hour dietary recall questionnaire. A MIND diet score was evaluated based on the intake of ten beneficial and five unhealthy food groups and the scores were further grouped into tertiles. The outcome of interest was incident IBD, Crohn's disease (CD), and ulcerative colitis (UC). Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models adjusted for demographic characteristics, lifestyle factors, cancer history, and other dietary factors. Mediation analyses were performed to evaluate the role of systemic inflammation and metabolic disorders represented by the integrated biomarkers in the MIND diet-IBD association. Results: After a mean follow-up of 10.7 years, we documented 825 incident IBD cases (250 CD and 575 UC). The average age of the participants was 56.2 years, of which 55.0% were females. We found that greater adherence to the MIND diet, represented by a higher diet score, was associated with a lower risk of IBD (HRcomparing extreme tertiles 0.74, 95% CI 0.62-0.90, p = 0.002; p for trend = 0.005), CD (HR 0.66, 95% CI 0.47-0.94, p = 0.022; p for trend = 0.023), and UC (HR 0.78, 95% CI 0.62-0.98, p = 0.031; p for trend = 0.022). The associations were partially mediated by metabolic and inflammation status (mediation proportion: 5.5-15.9%). Conclusion: We found higher adherence to the MIND diet was associated with a lower risk of IBD, and that inflammatory and metabolic conditions may play an important role in the underlying mechanistic pathways.

S100A8-Mediated Inflammatory Signaling Drives Colorectal Cancer Progression via the CXCL5/CXCR2 Axis.

Background: S100A8/S100A9 belong to the S100 calcium-binding protein family and play an essential role in the progression of chronic inflammation in diseases. It also regulates various biological processes such as tumor cell survival, apoptosis, and invasive metastasis. The extracellular form of S100A8/S100A9 functions by modulating cellular oxidative metabolism and facilitating inflammation-to-cancer progression. This modulation occurs through specific binding to receptors like RAGE and TLR4 and activation of signaling pathways including STAT3 and NF-κB. In tumor cells, S100A8 and S100A9 induce phenotypic changes by influencing calcium ion concentrations and other pathways. However, the precise function of high S100A8/S100A9 expression in colorectal cancer cells remains unclear. Methods: To explore the role of S100A8/S100A9 in colorectal cancer, we used immunohistochemistry and data from GEO and TCGA databases to analyze its expression in colorectal cancer cells, normal intestinal mucosa, and adjacent tissues. Functional models of high S100A8/S100A9 expression in colorectal cancer cells were established through transfection with overexpression plasmids. Protein microarrays, enzyme-linked immunosorbent assays (ELISAs), and real-time PCR were employed to assess the expression and secretion of 40 cytokines. MTT and Transwell invasion assays were conducted to evaluate changes in cell proliferation, invasion, and chemotaxis. Finally, tail vein and subcutaneous tumorigenesis assays assessed cell proliferation and migration in vivo. Results: We observed significantly higher expression of S100A8/S100A9 in colorectal cancer epithelial cells compared to normal intestinal mucosa and adjacent tissues. Overexpression of S100A8/S100A9 in mouse colon cancer cells CT26.WT led to differential increases in the secretion levels of various cytokines (CXCL5, CXCL11, GM-CSF, G-CSF, IL1a, IL1b, sTNF RI, and CCL3). Additionally, this overexpression activated signaling pathways such as STAT3, NF-κB, and ERK-MAPK. The synthesis and secretion of inflammatory factors could be inhibited by using NF-κB and ERK-MAPK pathway inhibitors. Moreover, S100A8 promotes the proliferation and invasion of colon cancer cells. Notably, the CXCR2 inhibitor (SB265610) effectively reversed the phenotypic changes induced by the CXCL5/CXCR2 biological axis. Conclusions: Our findings indicate that increased expression of S100A8 and S100A9 in colon cancer epithelial cells enhances the secretion of inflammatory factors by activating NF-κB, ERK-MAPK, and other signaling pathways. S100A8 facilitates colon cancer cell proliferation, invasion, and metastasis through the CXCL5/CXCR2 biological axis.

HDAC6 inhibitor ACY-1215 enhances STAT1 acetylation to block PD-L1 for colorectal cancer immunotherapy.

The search for effective combination therapy with immune checkpoint inhibitors (ICI) has become important for cancer patients who do not respond to the ICI well. Histone deacetylases (HDACs) inhibitors have attracted wide attention as anti-tumor agents. ACY-1215 is a selective inhibitor of HDAC6, which can inhibit the growth of a variety of tumor. We previously revealed that HDAC family is highly expressed in colorectal cancer specimens and mouse models. In this study, ACY-1215 was combined with anti-PD1 to treat tumor-bearing mice associated with colorectal cancer. ACY-1215 combined with anti-PD1 effectively inhibited the colorectal tumor growth. The expression of PD-L1 in tumor of mice were inhibited by ACY-1215 and anti-PD1 combination treatment, whereas some biomarkers reflecting T cell activation were upregulated. In a co-culture system of T cells and tumor cells, ACY-1215 helped T cells to kill tumor cells. Mechanically, HDAC6 enhanced the acetylation of STAT1 and inhibited the phosphorylation of STAT1, thus preventing STAT1 from entering the nucleus to activate PD-L1 transcription. This study reveals a novel regulatory mechanism of HDAC6 on non-histone substrates, especially on protein acetylation. HDAC6 inhibitors may be of great significance in tumor immunotherapy and related combination strategies.

Fatty acids and lipid mediators in inflammatory bowel disease: from mechanism to treatment.

Inflammatory Bowel Disease (IBD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract. Though the pathogenesis of IBD remains unclear, diet is increasingly recognized as a pivotal factor influencing its onset and progression. Fatty acids, essential components of dietary lipids, play diverse roles in IBD, ranging from anti-inflammatory and immune-regulatory functions to gut-microbiota modulation and barrier maintenance. Short-chain fatty acids (SCFAs), products of indigestible dietary fiber fermentation by gut microbiota, have strong anti-inflammatory properties and are seen as key protective factors against IBD. Among long-chain fatty acids, saturated fatty acids, trans fatty acids, and ω-6 polyunsaturated fatty acids exhibit pro-inflammatory effects, while oleic acid and ω-3 polyunsaturated fatty acids display anti-inflammatory actions. Lipid mediators derived from polyunsaturated fatty acids serve as bioactive molecules, influencing immune cell functions and offering both pro-inflammatory and anti-inflammatory benefits. Recent research has also highlighted the potential of medium- and very long-chain fatty acids in modulating inflammation, mucosal barriers, and gut microbiota in IBD. Given these insights, dietary intervention and supplementation with short-chain fatty acids are emerging as potential therapeutic strategies for IBD. This review elucidates the impact of various fatty acids and lipid mediators on IBD and delves into potential therapeutic avenues stemming from these compounds.

Pancreatic cancer challenge in 52 Asian countries: age-centric insights and the role of modifiable risk factors (1990-2019).

Background: Pancreatic cancer is renowned for its elevated incidence and mortality rates on a global scale. The disease burden of pancreatic cancer is anticipated to increase, particularly in Asia, due to its vast and rapidly aging population. Methods: Data from the Global Burden of Disease 2019 were analyzed for pancreatic cancer burden across 52 countries in Asia, including the incidence, mortality, and disability-adjusted life years (DALY) for pancreatic cancer, with a focus on risk factors such as high body mass index (BMI), elevated fasting plasma glucose, and smoking. We applied the Estimated Annual Percentage Change, the Age-Period-Cohort model, and decomposition analysis to evaluate incidence trends and effects. Results: From 1990 to 2019, both incidence and mortality rates of pancreatic cancer in Asia significantly increased, with an average annual standardized incidence rate change of 1.73%. Males consistently exhibited higher rates than females, with smoking as a key risk factor. Central Asia reported the highest rates, and South Asia the lowest. The incidence rose with age, peaking in those aged 70~74. The disease burden increased in all age groups, particularly in populations aged 55 and above, representing 84.41% of total cases in 2019, up from 79.01% in 1990. Pancreatic cancer ranked the fifth in incidence among six major gastrointestinal tumors but presented a significant growth rate of mortality and DALY. Conclusion: With the growing, aging population in Asia, the pancreatic cancer burden is projected to escalate, bringing a significant public health challenge. Hence, comprehensive public health strategies emphasizing early detection, risk modification, and optimized treatment of pancreatic cancer are imperative.

Evolving Trends and Burden of Inflammatory Bowel Disease in Asia, 1990-2019: A Comprehensive Analysis Based on the Global Burden of Disease Study.

BACKGROUND: Asia's inflammatory bowel disease (IBD) burden has rapidly increased recently, but the epidemiological trends in Asia remain unclear. We report IBD's incidence, prevalence, mortality, and Disability-Adjusted Life Years (DALY) in 52 Asian countries from 1990 to 2019. METHODS: Data from the Global Burden of Disease 2019 were analyzed for IBD burden across 52 countries, using metrics like incidence, prevalence, mortality rates, and DALY. The epidemiological trend of IBD from 1990 to 2019 was assessed with the Joinpoint and APC methods. Decomposition and frontier analyses examined factors behind IBD case and death changes. The NORPRED forecasted Asia's morbidity and mortality trends from 2019 to 2044. RESULTS: From 1990 to 2019, The incidence and prevalence of IBD increased in Asia, while mortality and DALY decreased. East Asia had the highest increase in disease burden. IBD incidence was highest among the 30-34 age group, with prevalence peaking in the 45-49 age group. In high-income regions, IBD peak age shifted to younger groups. Decompose analysis showed population growth as the primary factor for the increasing IBD cases in Asia. NORDPRED model predicted a continued IBD burden increase in Asia over the next 25 years. CONCLUSIONS: Between 1990 and 2019, ASIR and ASPR of IBD in Asia increased, while ASMR and ASDR decreased. Due to population growth and aging, the IBD burden is expected to rise over the next 25 years, particularly in East Asia.

Higher dietary fibre intake is associated with lower risk of inflammatory bowel disease: prospective cohort study.

BACKGROUND: Limited prospective studies that have examined the association of dietary fibre with IBD have provided inconsistent evidence. AIM: To examine any associations between dietary fibre intake and subsequent incidence of IBD, Crohn's disease (CD) and ulcerative colitis (UC) METHODS: We conducted a prospective cohort study of 470,669 participants from the UK Biobank and estimated dietary fibre intake from a valid food frequency questionnaire at baseline. Incident IBD was ascertained from primary care data and inpatient data. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between dietary fibre intake and the risk of IBD, CD and UC. RESULTS: During an average follow-up of 12.1 years, we ascertained 1473 incident IBD cases, including 543 cases of CD and 939 cases of UC. Comparing the lowest quintiles, an inverse association was observed between dietary fibre intake and risk of IBD (HR 0.74, 95% CI 0.58-0.93, p = 0.011) and CD (HR 0.48, 95% CI 0.32-0.72, p < 0.001), but not UC (HR 0.92, 95% CI 0.69-1.24, p = 0.595). For specified sources, dietary fibre intake from fruit and bread decreased the risk of CD, while dietary fibre intake from cereal decreased the risk of UC. CONCLUSIONS: Higher consumption of dietary fibre was associated with a lower risk of IBD and CD, but not UC. Our findings support current recommendations to increase the intake of dietary fibre.

Higher Fiber Intake is Associated with Reduced Risk of Related Surgery among Individuals with Inflammatory Bowel Disease in a Prospective Cohort Study.

BACKGROUND: Evidence for the effects of dietary fiber on adverse outcomes in individuals with inflammatory bowel disease (IBD) is insufficient and controversial. OBJECTIVES: We aimed to prospectively explore the association between dietary fiber intake and the risk of IBD-related surgery. METHODS: We identified 5580 individuals with diagnosed IBD [Crohn disease (CD, n = 1908) and ulcerative colitis (UC, n = 3672)] at baseline in the UK Biobank via electronic medical records and self-reported information. Dietary fiber intake was estimated by a partial fiber score derived from a valid food frequency questionnaire. IBD-related surgery (enterotomy, perianal surgery, and others) was ascertained via inpatient data. Cox proportional model was applied to estimate hazard ratios with 95% confidence intervals (CIs) of dietary fiber in quartiles for the risk of IBD-related surgery. RESULTS: During a mean follow-up period of 11.2 y, we documented 624 IBD-related surgery among 5580 individuals with IBD (mean age, 57.3; 52.8% females). Compared with individuals in the lowest quartiles, those with second to fourth quartiles of fiber intake were associated with 23% (95% CI: 5%, 38%, P = 0.015), 29% (95% CI: 11%, 43%, P = 0.003), and 28% (95% CI: 10%, 43%, P = 0.005) reduced risk (P-trend = 0.002) of IBD-related surgery. Similar associations were observed in CD (P-trend = 0.005) but not UC (P-trend = 0.131). We observed inverse associations of fiber in vegetables and fruits (P-trend = 0.017 and 0.007) but positive associations of fiber in bread (P-trend = 0.046) with the risk of IBD-related surgery. CONCLUSIONS: Higher intake of fiber is associated with reduced IBD-related surgery risk in patients with IBD with CD but not UC.

Adverse health effects of emerging contaminants on inflammatory bowel disease.

Inflammatory bowel disease (IBD) is becoming increasingly prevalent with the improvement of people's living standards in recent years, especially in urban areas. The emerging environmental contaminant is a newly-proposed concept in the progress of industrialization and modernization, referring to synthetic chemicals that were not noticed or researched before, which may lead to many chronic diseases, including IBD. The emerging contaminants mainly include microplastics, endocrine-disrupting chemicals, chemical herbicides, heavy metals, and persisting organic pollutants. In this review, we summarize the adverse health effect of these emerging contaminants on humans and their relationships with IBD. Therefore, we can better understand the impact of these new emerging contaminants on IBD, minimize their exposures, and lower the future incidence of IBD.

Willingness to Undergo Gastroscopy for Early Gastric Cancer Screening and Its Associated Factors During the COVID-19 Pandemic - A Nationwide Cross-Sectional Study in China.

Purpose: This study aimed to investigate the willingness of Chinese adults aged 40 years and older to undergo gastroscopy for gastric cancer (GC) screening during the COVID-19 pandemic in 2020. The secondary purpose was to identify factors influencing willingness to undergo gastroscopy. Methods: A cross-sectional questionnaire survey was conducted in selected cities and counties from nine provinces in China using a multi-stage sampling approach. A multivariate logistic regression model was used to determine the independent predictors of willingness to undergo gastroscopy. Results: This study included 1900 participants, and 1462 (76.95%) responded that they would undergo gastroscopy for GC screening. Participants of younger age, from the eastern region, living in an urban area, with higher educational levels, with Helicobacter pylori (H. pylori) infection, or with precancerous stomach lesions, were more willing to undergo gastroscopy. The top four reasons to reject gastroscopy were fear of pain or discomfort, worry about a possible devastating test result, no symptoms in self-feeling, and concern about the high expense. Of all those who would reject gastroscopy for GC screening, 36.76% (161/438) would be willing to accept painless gastroscopy, while 24.89% (109/438) would be willing to undergo gastroscopy screening if higher medical reimbursement rates were available. Participants considered that gastroscopy was a relatively fearful and unknown procedure, accompanied by high risks and benefits compared to all other life events. Conclusion: In general, 76.95% of participants over 40 years old were willing to undergo gastroscopy for GC screening in China during the COVID-19 pandemic. Participants' willingness to undergo GC screening increased due to medical resource constraints and increased interest in their health. Individuals with H. pylori infection are more likely to undergo gastroscopy, whereas old age individuals, those with lower educational levels, and those living in rural areas are more likely to reject gastroscopy.

Construction of a molecular inflammatory predictive model with histone modification-related genes and identification of CAMK2D as a potential response signature to infliximab in ulcerative colitis.

Background: Ulcerative colitis (UC) is a lifelong inflammatory disease affecting the rectum and colon with numerous treatment options that require an individualized treatment plan. Histone modifications regulate chromosome structure and gene expression, resulting in effects on inflammatory and immune responses. However, the relationship between histone modification-related genes and UC remains unclear. Methods: Transcriptomic data from GSE59071 and GSE66407 were obtained from the Gene Expression Omnibus (GEO), encompassing colonic biopsy expression profiles of UC patients in inflamed and non-inflamed status. Differentially expressed gene (DEG) analyses, functional enrichment analyses, weighted gene co-expression network analysis (WGCNA), and random forest were performed to identify histone modification-related core genes associated with UC inflammation. Features were screened through the least absolute shrinkage and selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE), establishing a molecular inflammatory predictive model using logistic regression. The model was validated in the GSE107499 dataset, and the performance of the features was assessed using receiver operating characteristic (ROC) and calibration curves. Immunohistochemistry (IHC) staining of colonic biopsy tissues from UC patients treated with infliximab was used to further confirm the clinical application value. Univariate logistic regression on GSE14580 highlighted features linked to infliximab response. Results: A total of 253 histone modification-related DEGs were identified between inflammatory and non-inflammatory patients with UC. Seven key genes (IL-1ß, MSL3, HDAC7, IRF4, CAMK2D, AUTS2, and PADI2) were selected using WGCNA and random forest. Through univariate logistic regression, three core genes (CAMK2D, AUTS2, and IL-1ß) were further incorporated to construct the molecular inflammatory predictive model. The area under the curve (AUC) of the model was 0.943 in the independent validation dataset. A significant association between CAMK2D protein expression and infliximab response was observed, which was validated in another independent verification set of GSE14580 from the GEO database. Conclusion: The molecular inflammatory predictive model based on CAMK2D, AUTS2, and IL-1ß could reliably distinguish the mucosal inflammatory status of UC patients. We further revealed that CAMK2D was a predictive marker of infliximab response. These findings are expected to provide a new evidence base for personalized treatment and management strategies for UC patients.

Greater Adherence to Cardioprotective Diet Can Reduce Inflammatory Bowel Disease Risk: A Longitudinal Cohort Study.

Background: The cardioprotective diet was reported to be associated with several chronic cardiometabolic diseases through an anti-inflammation effect. However, the association between the cardioprotective diet and the risk of inflammatory bowel disease (IBD) was unclear and deserved to be further explored. Methods: We calculated the cardioprotective diet score based on the consumptions of seven common food groups using the validated food frequency questionnaire data in the UK Biobank. Incident IBD was ascertained from primary care data, inpatient data, and the death registry. Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between the cardioprotective diet score and the risk of IBD. Results: During a mean follow-up of 12.1 years, we documented 2717 incident IBD cases, including 851 cases of Crohn's disease and 1866 cases of ulcerative colitis. Compared to participants with a cardioprotective diet score of 0−1, we observed a decreased risk of IBD among participants with cardioprotective diet scores of 3 (HR 0.85, 95% CI 0.73−0.99), 4 (HR 0.84, 95% CI 0.72−0.98), and 5−7 (HR 0.77, 95% CI 0.66−0.89) (p-trend < 0.001). Conclusions: A greater adherence to the cardioprotective diet was associated with a lower risk of IBD. Our finding highlighted the importance of focusing on the cardioprotective diet to prevent IBD.

Sex-Specific Differences in MicroRNA Expression During Human Fetal Lung Development.

Background: Sex-specific differences in fetal lung maturation have been well described; however, little is known about the sex-specific differences in microRNA (miRNA) expression during human fetal lung development. Interestingly, many adult chronic lung diseases also demonstrate sex-specific differences in prevalence. The developmental origins of health and disease hypothesis suggests that these sex-specific differences in fetal lung development may influence disease susceptibility later in life. In this study, we performed miRNA sequencing on human fetal lung tissue samples to investigate differential expression of miRNAs between males and females in the pseudoglandular stage of lung development. We hypothesized that differences in miRNA expression are present between sexes in early human lung development and may contribute to the sex-specific differences seen in pulmonary diseases later in life. Methods: RNA was isolated from human fetal lung tissue samples for miRNA sequencing. The count of each miRNA was modeled by sex using negative binomial regression models in DESeq2, adjusting for post-conception age, age2, smoke exposure, batch, and RUV factors. We tested for differential expression of miRNAs by sex, and for the presence of sex-by-age interactions to determine if miRNA expression levels by age were distinct between males and females. Results: miRNA expression profiles were generated on 298 samples (166 males and 132 females). Of the 809 miRNAs expressed in human fetal lung tissue during the pseudoglandular stage of lung development, we identified 93 autosomal miRNAs that were significantly differentially expressed by sex and 129 miRNAs with a sex-specific pattern of miRNA expression across the course of the pseudoglandular period. Conclusion: Our study demonstrates differential expression of numerous autosomal miRNAs between the male and female developing human lung. Additionally, the expression of some miRNAs are modified by age across the pseudoglandular stage in a sex-specific way. Some of these differences in miRNA expression may impact susceptibility to pulmonary disease later in life. Our results suggest that sex-specific miRNA expression during human lung development may be a potential mechanism to explain sex-specific differences in lung development and may impact subsequent disease susceptibility.

Airway epithelial Paraoxonase-2 in obese asthma.

BACKGROUND: Obesity in asthmatics has been associated with higher airway oxidative stress in which dysfunctional mitochondria are a potential contributing source of excess free radicals. Paraoxonase 2 (PON2) plays an important role in reducing mitochondrial-derived oxidative stress and could, therefore, have therapeutic potential in these patients. OBJECTIVES: We used primary human bronchial epithelial cells (HBECs) from asthmatics and healthy controls to evaluate: a) protein levels of Paraoxonase 2 and b) to test the potential protective effect of quercetin supplementation in cells under oxidative stress conditions. RESULTS: Compared to lean controls, obese asthmatics had significantly lower PON2 airway epithelial levels (respectively, 1.08 vs. 0.47 relative units normalized by GAPDH) (p-value < 0.006). Treating HBECs in vitro for 24 hrs. with 25µM quercetin significantly increased PON2 protein levels: 15.5 treated cells vs. 9.8 untreated cells (relative units normalized by GAPDH) (p value = 0.004). Notably, compared to untreated cells, quercetin supplementation reduces mitochondrial superoxide and hydrogen peroxide production on HBECs cells exposed to different oxidative stress triggers such as 1-2 Naphthoquinone (1-2 NQ) and hydrogen peroxide, suggesting that PON2 might play a protective role ameliorating oxidative injury on human airway epithelium. CONCLUSION: Compared to lean controls, obese asthmatics have significantly reduced PON2 levels in airway epithelial cells. Treatment with quercetin in vitro increased PON2 protein levels and prevented oxidative stress from different types of stimuli. Hence, quercetin supplementation may be a potential therapeutic strategy to prevent obesity-mediated airway oxidative stress in obese asthmatics.

Metformin prevents ischaemic ventricular fibrillation in metabolically normal pigs.

AIMS/HYPOTHESIS: Metformin is the drug most often used to treat type 2 diabetes. Evidence suggests that metformin may reduce mortality of individuals with type 2 diabetes, but the mechanism of such an effect is unknown and outcomes of metformin treatment in people without diabetes have not been determined. If metformin favourably affected mortality of non-diabetic individuals, it might have even broader therapeutic utility. We evaluated the effect of metformin on myocardial energetics and ischaemic ventricular fibrillation (VF) in metabolically normal pigs. METHODS: Domestic farm pigs were treated with metformin (30 mg kg-1 day-1 orally for 2-3 weeks; n = 36) or received no treatment (n = 37). Under anaesthesia, pigs underwent up to 90 min low-flow regional myocardial ischaemia followed by 45 min of reperfusion. Pigs were monitored for arrhythmia, monophasic action potential morphology, haemodynamics and myocardial substrate utilisation, AMP-activated protein kinase (AMPK) phosphorylation activity and ATP concentration. RESULTS: Death due to VF occurred in 12% of pigs treated with metformin compared with 50% of untreated controls (p = 0.03). The anti-fibrillatory effect of metformin was associated with attenuation of action potential shortening in ischaemic myocardium (p = 0.02) and attenuation of the difference in action potential duration between ischaemic and non-ischaemic regions (p < 0.001) compared with untreated controls. Metformin had no effect on myocardial contractile function, oxygen consumption, or glucose or lactate utilisation. During ischaemia, however, metformin treatment amplified the activation of AMPK and preserved ATP concentration in myocardium compared with untreated controls (each p < 0.05). CONCLUSIONS/INTERPRETATION: Chronic treatment of metabolically normal pigs with metformin at a clinically relevant dose reduces mortality from ischaemic VF. This protection is associated with preservation of myocardial energetics during ischaemia. Maintenance of myocardial ATP concentration during ischaemia is likely to prevent action potential shortening, heterogeneity of repolarisation, and propensity for lethal arrhythmia. The findings suggest that metformin might be protective in non-diabetic individuals with coronary heart disease.

Impaired contractile recovery after low-flow myocardial ischemia in a porcine model of metabolic syndrome.

Clinical metabolic syndrome conveys a poor prognosis in patients with acute coronary syndrome, not fully accounted for by the extent of coronary atherosclerosis. To explain this observation, we determined whether postischemic myocardial contractile and metabolic function are impaired in a porcine dietary model of metabolic syndrome without atherosclerosis. Micropigs (n = 28) were assigned to a control diet (low fat, no added sugars) or an intervention diet (high saturated fat and simple sugars, no added cholesterol) for 7 mo. The intervention diet produced obesity, hypertension, dyslipidemia, and impaired glucose tolerance, but not atherosclerosis. Under open-chest, anesthetized conditions, pigs underwent 45 min of low-flow myocardial ischemia and 120 min of reperfusion. In both diet groups, contractile function was similar at baseline and declined similarly during ischemia. However, after 120 min of reperfusion, regional work recovered to 21 ± 12% of baseline in metabolic syndrome pigs compared with 61 ± 13% in control pigs (P = 0.01). Ischemia-reperfusion caused a progressive decline in mechanical/metabolic efficiency (regional work/O2 consumption) in metabolic syndrome hearts, but not in control hearts. Metabolic syndrome hearts demonstrated altered fatty acyl composition of cardiolipin and increased Akt phosphorylation in both ischemic and nonischemic regions, suggesting tonic activation. Metabolic syndrome hearts used more fatty acid than control hearts (P = 0.03). When fatty acid availability was restricted by prior insulin exposure, differences between groups in postischemic contractile recovery and mechanical/metabolic efficiency were eliminated. In conclusion, pigs with characteristics of metabolic syndrome demonstrate impaired contractile and metabolic recovery after low-flow myocardial ischemia. Contributory mechanisms may include remodeling of cardiolipin, abnormal activation of Akt, and excessive utilization of fatty acid substrates.

Calpain inhibition preserves talin and attenuates right heart failure in acute pulmonary hypertension.

Right heart failure from right ventricular (RV) pressure overload is a major cause of morbidity and mortality, but its mechanism is incompletely understood. We tested the hypothesis that right heart failure during 4 hours of RV pressure overload is associated with alterations of the focal adhesion protein talin, and that the inhibition of calpain attenuates RV dysfunction and preserves RV talin. Anesthetized open-chest pigs treated with the calpain inhibitor MDL-28170 (n = 20) or inactive vehicle (n = 23) underwent 4 hours of RV pressure overload by pulmonary artery constriction (initial RV systolic pressure, 64 ± 1 and 66 ± 1 mm Hg in MDL-28170 and vehicle-treated pigs, respectively). Progressive RV contractile dysfunction was attenuated by MDL-28170: after 4 hours of RV pressure overload, RV systolic pressure was 44 ± 4 mm Hg versus 49 ± 6 mm Hg (P = 0.011), and RV stroke work was 72 ± 5% of baseline versus 90 ± 5% of baseline, (P = 0.027), in vehicle-treated versus MDL-28170-treated pigs, respectively. MDL-28170 reduced the incidence of hemodynamic instability (death or systolic blood pressure of < 85 mm Hg) by 46% (P = 0.013). RV pressure overload disrupted talin organization. MDL-28170 preserved talin abundance in the RV free wall (P = 0.039), and talin abundance correlated with the maintenance of RV free wall stroke work (r = 0.58, P = 0.0039). α-actinin and vinculin showed similar changes according to immunohistology. Right heart failure from acute RV pressure overload is associated with reduced talin abundance and disrupted talin organization. Calpain inhibition preserves the abundance and organization of talin and RV function. Calpain inhibition may offer clinical utility in treating acute cor pulmonale.

Thiazolidinedione drugs promote onset, alter characteristics, and increase mortality of ischemic ventricular fibrillation in pigs.

PURPOSE: Despite favorable metabolic and vascular effects, thiazolidinedione (TZD) drugs have not convincingly reduced cardiovascular mortality in clinical trials, raising the possibility of countervailing, off-target effects. We previously showed that TZDs block cardiac ATP-sensitive potassium (K(ATP)) channels in pigs. In this study, we investigated whether TZDs affect onset, spectral characteristics, and mortality of ischemic ventricular fibrillation (VF) and whether such effects are recapitulated by a non-selective K(ATP) blocker (glyburide) or a mitochondrial K(ATP) blocker (5-hydroxydecanoate). METHODS: A total of 121 anesthetized pigs were pre-treated with TZD (pioglitazone or rosiglitazone, 1 mg/kg IV, resulting in clinically relevant plasma concentrations), glyburide (1 mg/kg IV), 5-hydroxydecanoate (5 mg/kg IV) or inert vehicle. Ischemia was produced by occlusion of the left anterior descending coronary artery. In a subset of pigs treated with rosiglitazone or vehicle, ischemic preconditioning was performed. RESULTS: VF developed in all but 6 pigs. In non-preconditioned pigs, onset of VF occurred sooner with pioglitazone (11±3 min, p<0.05) or rosiglitazone (14±3 min, p=0.06) than with vehicle (20±2 min). Defibrillation of VF was successful in 44% of pigs treated with vehicle, compared with 0% with pioglitazone (p=0.057) and 33% with rosiglitazone (NS). After ischemic preconditioning, defibrillation was successful in 62% of pigs treated with vehicle, compared with 26% treated with rosiglitazone (p=0.03). TZDs attenuated slowing of conduction due to ischemia and shifted ECG power spectra during VF toward higher frequencies. All effects of TZDs were recapitulated by glyburide, but not by 5-hydroxydecanoate, supporting an interaction of TZDs with the sarcolemmal K(ATP) channel. CONCLUSION: In a porcine model, TZDs promote onset and increase mortality of ischemic VF, associated with alterations of conduction and VF spectral characteristics. Similar effects in a clinical setting might adversely impact cardiovascular mortality.

Calpain inhibition attenuates right ventricular contractile dysfunction after acute pressure overload.

Right ventricular contractile failure from acute RV pressure overload is an important cause of morbidity and mortality, but the mechanism of RV failure in this setting is incompletely defined. We hypothesized that RV dysfunction from acute RV pressure overload is, in part, due to activation of calpain, and that calpain inhibition would therefore attenuate RV dysfunction. Anesthetized, open chest pigs were treated with the calpain inhibitor MDL-28170 or with inactive vehicle, and then subjected to acute RV pressure overload for 90 min. RV contractile function was assessed by the regional Frank-Starling relation. RV myocardial tissue was analyzed for evidence of calpain activation and calpain-mediated proteolysis. RV pressure overload caused severe contractile dysfunction, along with significant alterations in the endogenous calpain inhibitor calpastatin typical of calpain activation. MDL-28170 attenuated RV free wall dysfunction by more than 50%. However, there were no differences in degradation of spectrin, desmin, troponin-I or SERCA2 between SHAM operated pigs and pigs subjected to acute RV pressure overload, or between vehicle and MDL-28170 treated pigs. Acute RV pressure overload causes calpain activation, and RV contractile dysfunction from acute RV pressure overload is attenuated by the calpain inhibitor MDL-28170; however, the effect is not explained by inhibition of calpain-mediated degradation of spectrin, desmin, troponin-I or SERCA2. Because this is the first report of any agent that can directly attenuate RV contractile dysfunction in acute RV pressure overload, further investigation of the mechanism of action of MDL-28170 in this setting is warranted.