Metabolic dysfunction mediated by HIF-1α contributes to epithelial differentiation defects in eosinophilic esophagitis.

BACKGROUND: Investigating the contributory role that epithelial cell metabolism plays in allergic inflammation is a key factor to understanding what influences dysfunction and the pathogenesis of the allergic disease eosinophilic esophagitis (EoE). We previously highlighted that the absence of hypoxia signaling through hypoxia-inducible factor (HIF)-1α in EoE contributes to esophageal epithelial dysfunction. However, metabolic regulation by HIF-1α has not been explored in esophageal allergy. OBJECTIVES: We sought to define the role of HIF-1α-mediated metabolic dysfunction in esophageal epithelial differentiation processes and barrier function in EoE. METHODS: In RNA sequencing of EoE patient biopsy samples, we observed the expression pattern of key genes involved in mitochondrial metabolism/oxidative phosphorylation (OXPHOS) and glycolysis. Seahorse bioenergetics analysis was performed on EPC2-hTERT cells to decipher the metabolic processes involved in epithelial differentiation processes. In addition, air-liquid interface cultures were used to delineate metabolic dependency mechanisms required for epithelial differentiation. RESULTS: Transcriptomic analysis identified an increase in genes associated with OXPHOS in patients with EoE. Epithelial origin of this signature was confirmed by complex V immunofluorescence of patient biopsy samples. Bioenergetic analysis in vitro revealed that differentiated epithelium was less reliant on OXPHOS compared with undifferentiated epithelium. Increased OXPHOS potential and reduced glycolytic capacity was mirrored in HIF1A-knockdown EPC2-hTERT cells that exhibited a significant absence of terminal markers of epithelial differentiation, including involucrin. Pharmacologic glucose transport inhibition phenocopied this, while rescue of the HIF-1α-deficient phenotype using the pan-prolyl hydroxylase inhibitor dimethyloxalylglycine resulted in restored expression of epithelial differentiation markers. CONCLUSIONS: An OXPHOS-dominated metabolic pattern in EoE patients, brought about largely by the absence of HIF-1α-mediated glycolysis, is linked with the deficit in esophageal epithelial differentiation.

Hepatitis C community prevalence is over-estimated: a prospective, birth cohort study.

BACKGROUND: Hepatitis C virus infection is often asymptomatic, and many patients may be unaware they are infected. Community-based, birth cohort screening has been advocated to identify these patients. It has been estimated that 0.7-1% of individuals born between 1965 and 1985 in Ireland are infected. The cost-effectiveness of screening is critically dependent on the population prevalence. AIMS: The aim is to determine the community prevalence of hepatitis C virus infection in the birth cohort 1965-1985. METHODS: Residual serum samples from blood tests ordered by community general practitioners were anonymised and analysed for the presence of hepatitis C antibody ± antigen. Twelve large general hospitals throughout the country participated. RESULTS: A total of 14,320 samples were tested, 9347 of which were from the birth cohort 1965-1985. Seventy-two samples were positive for hepatitis C antibody of which 12 were positive for hepatitis C antigen (17%). The overall prevalence of hepatitis C antigen in the birth cohort was 0.09%. A higher prevalence (0.39%) was identified in males in two urban areas of Dublin. CONCLUSIONS: Hepatitis C virus seroprevalence was much lower than previously estimated. The proportion of antibody positive patients with hepatitis C antigen was also lower than expected suggesting the effects of treatment and/or high spontaneous viral clearance. Universal birth cohort screening is unlikely to be cost-effective. Targeted birth cohort screening in high prevalence areas could be considered.

Cardiac Magnetic Resonance at 3.0 T in Patients With C282Y Homozygous Hereditary Hemochromatosis: Superiority of Radial and Circumferential Strain Over Cardiac T2* Measurements at Baseline and at Post Venesection Follow-up.

BACKGROUND: Iron-overload cardiomyopathy initially manifests with diastolic dysfunction and can progress to dilated cardiomyopathy if untreated. Previous studies have shown that patients with primary and secondary hemochromatosis can have subclinical left ventricle dysfunction with abnormalities on strain imaging. This study aimed to evaluate the relationship between cardiac T2* values and myocardial-wall strain in patients with hereditary hemochromatosis (HH) at the time of diagnosis and after a course of venesection treatment. MATERIALS AND METHODS: Baseline cardiac magnetic resonance (CMR) at 3 T was performed in 19 patients with newly diagnosed HH with elevated serum ferritin levels and repeated after a course of treatment with venesection. Quantitative T2* mapping and strain analysis were performed offline using dedicated relaxometry fitting and feature-tracking software. RESULTS: The majority (84%) of patients had normal baseline myocardial T2* values (mean 19.3 ms, range 8.9 to 31.2 ms), which improved significantly after venesection (mean 24.1 ms, range 11 to 38.1 ms) ( P =0.021). Mean global radial strain significantly improved from 25.0 (range: 15.6 to 32.9) to 28.3 (range: 19.8 to 35.8) ( P =0.001) and mean global circumferential strain improved, decreasing from -15.7 (range: -11.1 to -19.2) to -17.1 (range: -13.0 to -20.1) ( P =0.001). CONCLUSION: Patients with HH may have normal T2* values in the presence of subclinical left ventricle dysfunction, which can be detected by abnormal radial and circumferential strain. As strain imaging improves following venesection in HH, it may serve as a useful biomarker to guide treatment.

New hepatitis C virus infection, re-infection and associated risk behaviour in male Irish prisoners: a cohort study, 2019.

BACKGROUND: Prisoners are recognised as a high-risk population and prisons as high-risk locations for the transmission of hepatitis c virus (HCV) infection. Injecting drug use (IDU) is the main driver of HCV infection in prisoners and harm reduction services are often suboptimal in prison settings. HCV prevalence and incident data in prisoners is incomplete which impacts the public health opportunity that incarceration provides in identifying, treating and preventing HCV infection. The aim of this study is to identify new HCV infection and associated risk factors in an Irish male prison. METHODS: We conducted a follow up (18-month) cohort study on prisoners who had previously tested negative, self-cleared or had been successfully treated for HCV infection. We conducted the study in a male medium security prison located in Dublin Ireland (Mountjoy Prison) using HCV serology, a review of medical records and a researcher-administered questionnaire. RESULTS: 99 prisoners with a mean age of 33.2 yrs. participated in the study and 82(82.8%) completed a research-administered questionnaire. Over half (51%) had a history of drug use from a young age (14.8 yrs.), 49.9% a history of heroin use and 39% a history of IDU. The prevalence of HIV and hepatitis B virus core antibody was 3% and HCV antibody was 22.2%. No new HCV infections were identified in those who had never been infected (n = 77), had self-cleared (n = 9) or achieved sustained virological response (n = 12). Small numbers of prisoners continued to engage in risk-behaviour including, IDU both in the prison (n = 2) and the community (n = 3), sharing syringes (n = 1) and drug taking paraphernalia (n = 6) and receiving non-sterile tattoos (n = 3). CONCLUSION: Despite the high numbers of Irish prisoners with a history of IDU and HCV infection, new HCV infection is low or non-existent in this population. Small numbers of prisoners continue to engage in risk behaviour and larger studies are required to further understand HCV transmission in this cohort in an Irish and international context.

Improvement in cognitive impairment following a 12-week aerobic exercise intervention in individuals with non-cirrhotic chronic hepatitis C.

Cognitive impairment occurs in 30%-50% of patients with non-cirrhotic chronic hepatitis C virus (HCV) infection. Exercise is beneficial in preventing and treating cognitive impairment and cardiometabolic abnormalities in many chronic inflammatory diseases, but there are few studies investigating the impact of exercise in HCV infection. The study aimed to assess the effect of a 12-week aerobic exercise intervention on cognition and extrahepatic manifestations in individuals with HCV. In this nonrandomized controlled pilot study, individuals with HCV participated in a 12-week aerobic exercise intervention. Outcome measures included cognition (Montreal Cognitive Assessment [MOCA], Trail Making Test A & B [TMT-A; TMT-B], Digit Symbol Test [DST]), cardiorespiratory fitness (estimated V˙O2max ), physical activity (accelerometry), anthropometry, quality of life (depression; fatigue; sleep quality) and biochemical markers. Outcomes were assessed at baseline (T0), intervention completion (T1) and 12 weeks after intervention completion (T2). Thirty-one patients completed the study (exercise group n = 13, control group n = 18). In the exercise group, cognition improved at T1 in the TMT-A (31% mean improvement, p = 0.019), TMT-B (15% mean improvement, p = 0.012) time and MOCA (14% mean improvement, p ≤ 0.001). These improvements were not maintained at T2. Depression (p = 0.038), sleep quality (p = 0.002), fatigue (p = 0.037) and estimated V˙O2max (7.8 mL kg-1  min-1 [22%] mean increase, p = 0.004) also improved at T1. In conclusion, this study demonstrates the benefits of a 12-week aerobic exercise intervention in improving cognition, quality of life and cardiorespiratory fitness in individuals with HCV. Larger studies are needed to confirm these findings and strategies for continued exercise engagement in individuals with HCV are warranted for sustained benefits.

Comparison of medium to long-term outcomes of acute severe ulcerative colitis patients receiving accelerated and standard infliximab induction.

INTRODUCTION: Accelerated dose infliximab (IFX) induction is associated with reduced short-term colectomy rate in acute severe ulcerative colitis (ASUC). Data on medium/long-term outcomes of this strategy are limited. AIMS: Evaluate medium/long-term outcomes in patients receiving IFX induction for ASUC, comparing accelerated dose (AD) and standard dose (SD) induction. METHODS: Retrospective study of consecutive patients admitted with corticosteroid-refractory ASUC in four tertiary referral centres within INITIative IBD research network (www.initiativeibd.ie). IFX rescue was given either as SD (weeks 0, 2, 6) or AD (<28 days) from January 2010 to September 2017. AD induction has been utilised in participating centres since 2014. Consequently SD patients were subdivided based on time period of IFX rescue: historical SD group (SD1) (2010-2013) and current SD group (SD2) (2014-2017). Primary endpoint was time to colectomy; secondary endpoint was time to IFX discontinuation if induction was complete. RESULTS: 145 patients received rescue IFX (AD=58, SD1=32, SD2=55). Disease severity at induction was comparable between AD and SD1 groups; however, SD2 group had less severe disease: median C-reactive protein (CRP) 39, 44 and 20 mg/L for AD, SD1 and SD2 groups, respectively (p=0.026, Kruskal-Wallis); median CRP: albumin ratio was 1.4, 1.8 and 0.6 (p=0.016). Median follow-up for AD, SD1 and SD2 groups was 1.6 (IQR 1.1-3.1), 4.9 (IQR 2.6-5.5) and 1.5 (IQR 0.9-2.3) years. Time to colectomy was shorter in SD1 (log rank p=0.0013); no significant difference in time to colectomy was observed comparing AD and SD2 groups (log rank p=0.32). 123 patients (84%) completed IFX induction and received maintenance therapy. Time to IFX discontinuation was shorter in SD1 (log rank p=0.009). CONCLUSION: Time to colectomy is significantly prolonged with use of AD IFX in selected ASUC patients with more severe disease. Historical use of standard IFX induction for all ASUC patients is associated with inferior long-term outcomes.

Irish data on the safety and efficacy of vedolizumab in the treatment of inflammatory bowel disease.

SUMMARY: This study reviews the safety and efficacy of treatment with vedolizumab for patients with inflammatory bowel disease across 9 Irish hospitals. It generates valuable and timely real-world data on treatment outcomes to add to the existing evidence base. Our population represents a refractory cohort with most patients previously exposed to at least one anti-TNFa agent and expressing an inflammatory phenotype. Results are reassuringly similar to larger international studies with additional insights into potential predictors of treatment response. This study further supports the safety and efficacy of vedolizumab in the treatment of inflammatory bowel disease. Key SummaryVedolizumab has growing real world data on its safety and efficacy in the treatment of IBD. Data on predictors of response are lacking. Studies such as VARSITY require new real-world data to help identify the place VDZ will occupy in the treatment algorithm for IBDThis study provides national Irish data on the safety and efficacy of VDZ in the treatment of IBD. It gives insight into various predictors of response for both UC and CD. It strengthens the available body of evidence on the use of VDZ and helps us determine its position on the treatment algorithm.

Opt-out screening for HIV, hepatitis B and hepatitis C: observational study of screening acceptance, yield and treatment outcomes.

BACKGROUND: We initiated an emergency department (ED) opt-out screening programme for HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) at our hospital in Dublin, Ireland. The objective of this study was to determine screening acceptance, yield and the impact on follow-up care. METHODS: From July 2015 through June 2018, ED patients who underwent phlebotomy and could consent to testing were tested for HIV, HBV and HCV using an opt-out approach. We examined acceptance of screening, linkage to care, treatment and viral suppression using screening programme data and electronic health records. The duration of follow-up ranged from 1 to 36 months. RESULTS: Over the 36-month study period, there were 140 550 ED patient visits, of whom 88 854 (63.2%, 95% CI 63.0% to 63.5%) underwent phlebotomy and 54 817 (61.7%, 95% CI 61.4% to 62.0%) accepted screening for HIV, HBV and HCV, representing 41 535 individual patients. 2202 of these patients had a positive test result. Of these, 267 (12.1%, 95% CI 10.8% to 13.6%) were newly diagnosed with an infection and 1762 (80.0%, 95% CI 78.3% to 81.7%) had known diagnoses. There were 38 new HIV, 47 new HBV and 182 new HCV diagnoses. 81.5% (95% CI 74.9% to 87.0%) of known patients who were not linked were relinked to care after screening. Of the new diagnoses, 86.2% (95% CI 80.4 to 90.8%) were linked to care. CONCLUSION: Although high proportions of patients had known diagnoses, our programme was able to identify many new infected patients and link them to care, as well as relink patients with known diagnoses who had been lost to follow-up.

Improvements in cardiac function detected using echocardiography in patients with hereditary haemochromatosis.

BACKGROUND: Hereditary haemochromatosis is often not diagnosed until adulthood. Iron overload cardiomyopathy initially results in diastolic dysfunction and can result in arrhythmias and irreversible cardiac failure if untreated. The aim of this study was to investigate whether patients with newly diagnosed hereditary haemochromatosis without signs of heart failure exhibit subclinical alterations of cardiac function and to determine if cardiac function improved after 1 year of venesection. METHODS: Baseline echocardiography was performed on 25 patients with newly diagnosed hereditary haemochromatosis with elevated serum ferritin levels. The test was repeated after 1 year of treatment with venesection. Tissue Doppler imaging (TDI) and deformation (strain) imaging using speckle tracking were performed. Left atrial force was measured according to the Newtonian principle, in which force (dynes) = mass × acceleration. Left atrial force was calculated by the Manning method expressed as ρ × 0.53 × mitral annular orifice area × (peak A velocity)2. RESULTS: Radial strain showed a significant improvement after 1 year of venesection (increase from 38.8 to 52.6). The LAF showed a significant decrease after 1 year of venesection (median decrease = 0.6 (IQR 0, 1.60), p = 0.0004). Iso-volumetric relaxation time (IVRT) decreased significantly in patients after 1 year of venesection (decrease from 107.4 ± 16.2 to 97.68 ± 15.4 ms, p (0.0187)). CONCLUSION: Among all measurements, radial strain, IVRT and left atrial force were shown to significantly improve following a 1-year course of venesection, suggesting that these parameters could be used to identify subclinical cardiac dysfunction in patients with iron overload secondary to hereditary haemochromatosis and to guide intensification of venesection therapy.

Evaluating peer-supported screening as a hepatitis C case-finding model in prisoners.

BACKGROUND: Hepatitis C Virus (HCV) infection is endemic in prison populations, and HCV management in prisons is suboptimal. Incarceration is a public health opportunity to target this cohort. Community peer support increases HCV screening and treatment uptake. Prison peer workers have the potential to support the engagement of prisoners with health services and reduce stigma. This study's primary aim is to evaluate peer-supported screening as a model of active HCV case finding with a secondary aim to describe the HCV cascade among those infected including linkage to care and treatment outcomes. METHODS: An observational study was conducted in a medium-security Irish male prison housing 538 inmates, using a risk-based questionnaire, medical records, peer-supported screening, laboratory-based HCV serology tests and mobile elastography. RESULTS: A prison peer-supported screening initiative engaged large numbers of prisoners in HCV screening (n = 419). The mean age of participants was 32.8 years, 92% were Irish and 33% had a history of injecting drug use. Multiple risk factors for HCV acquisition were identified including needle sharing (16%). On serological testing, 87 (21%) were HCV Ab +ve and 50 (12%) were HCV RNA +ve of whom 80% were fibroscaned (25% showing evidence of liver disease). Eighty-six percent of those with active infection were linked with HCV care, with 33% undergoing or completing treatment. There was a high concordance with HCV disclosure at committal and serological testing (96% for HCV Ab +ve and 89% for HCV Ab -ve). CONCLUSION: Peer-supported screening is an effective active HCV case-finding model to find and link prisoners with untreated active HCV infection to HCV care.

The seroprevalence of untreated chronic hepatitis C virus (HCV) infection and associated risk factors in male Irish prisoners: a cross-sectional study, 2017.

IntroductionData on chronic hepatitis C (HCV) infection prevalence in European prisons are incomplete and impact the public health opportunity that incarceration provides.AimsWe aimed to estimate the seroprevalence of untreated chronic HCV infection and to identify associated risk factors in an Irish male prison.MethodsWe conducted a cross-sectional study involving a researcher-administered questionnaire, review of medical records and HCV serology.ResultsOf 422 prisoners (78.0% of the study population) who participated in the study, 298 (70.6%) completed the questionnaire and 403 (95.5%) were tested for HCV antibodies. Of those tested, 92 (22.8%) were HCV antibody-positive, and of those, 53 (57.6%) were HCV RNA-positive, 23 (25.0%) had spontaneous clearance, 16 (17.4%) had a sustained viral response, 10 (11.0%) were co-infected with HIV and six (6.0%) with HBV. The untreated chronic HCV seroprevalence estimate was 13.1% and the seroprevalence of HCV among prisoners with a history of injecting drug use (IDU) was 79.7%. Risk factors significantly associated with past HCV infection were IDU (p < 0.0001), having received a prison tattoo (p < 0.0001) or a non-sterile community tattoo (p < 0.0001), sharing needles and other drug-taking paraphernalia (p < 0.0001). Small numbers of prisoners had a history of sharing razors (n=10; 3.4%) and toothbrushes (n=3; 1.0%) while incarcerated. On multivariable analysis, history of receiving a non-sterile community tattoo was the only significant risk factor associated with HCV acquisition (after IDU was removed from the model) (p = 0.005, ß = 0.468).ConclusionThe level of untreated chronic HCV infection in Irish prisons is high, with IDU the main associated risk.

Golimumab effectiveness and safety in clinical practice for moderately active ulcerative colitis.

BACKGROUND AND AIMS: Golimumab (GLB) is an antitumour necrosis factor-α (anti-TNF) therapy that has shown efficacy as induction and maintenance therapy for ulcerative colitis (UC). We aimed to describe the outcome of GLB therapy for UC in a real-world clinical practice. PATIENTS AND METHODS: Consecutive patients receiving GLB for UC in six Irish Academic Medical Centres were identified. The primary study endpoint was the 6-month corticosteroid-free remission rate. The secondary endpoints included the 3-month clinical response, time free of GLB discontinuation and adverse events. RESULTS: Seventy-two patients were identified [57% men; median (range) age of 41.4 years (20.3-76.8); disease duration 6.6 years (0-29.9); follow-up 8.7 months (0.4-39.2)]. Sixty-four percent of patients were anti-TNF naive. The 3-month clinical response and the 6-month corticosteroid-free remission rates were 55 and 39%, respectively. Forty-four percent of patients discontinued GLB during the follow-up, median (95% confidence interval) time to GLB discontinuation 18.7 months (9.2-28.1). A C-reactive protein more than 5 mg/l at baseline was associated with failure to achieve 6-month corticosteroid-free remission and a shorter time to GLB discontinuation, odds ratio 0.2 (0.1-0.7), P=0.008, and hazard ratio (95% confidence interval) 2.8 (1.3-5.7), P=0.007, respectively. Adverse events occurred in 7% of patients (n=5), all of which were minor and self-limiting. CONCLUSION: These real-world clinical data suggest that GLB is an effective and safe therapy for a UC cohort with significant previous anti-TNF exposure. An elevated baseline C-reactive protein, likely reflective of increased inflammatory burden, is associated with a reduced likelihood of a successful outcome of GLB therapy.

Novel Sarcopenia-related Alterations in Sarcomeric Protein Post-translational Modifications (PTMs) in Skeletal Muscles Identified by Top-down Proteomics.

Sarcopenia, the age-related loss of skeletal muscle mass and strength, is a significant cause of morbidity in the elderly and is a major burden on health care systems. Unfortunately, the underlying molecular mechanisms in sarcopenia remain poorly understood. Herein, we utilized top-down proteomics to elucidate sarcopenia-related changes in the fast- and slow-twitch skeletal muscles of aging rats with a focus on the sarcomeric proteome, which includes both myofilament and Z-disc proteins-the proteins that constitute the contractile apparatuses. Top-down quantitative proteomics identified significant changes in the post-translational modifications (PTMs) of critical myofilament proteins in the fast-twitch skeletal muscles of aging rats, in accordance with the vulnerability of fast-twitch muscles to sarcopenia. Surprisingly, age-related alterations in the phosphorylation of Cypher isoforms, proteins that localize to the Z-discs in striated muscles, were also noted in the fast-twitch skeletal muscle of aging rats. This represents the first report of changes in the phosphorylation of Z-disc proteins in skeletal muscle during aging. In addition, increased glutathionylation of slow skeletal troponin I, a novel modification that may help protect against oxidative damage, was observed in slow-twitch skeletal muscles. Furthermore, we have identified and characterized novel muscle type-specific proteoforms of myofilament proteins and Z-disc proteins, including a novel isoform of the Z-disc protein Enigma. The finding that the phosphorylation of Z-disc proteins is altered in response to aging in the fast-twitch skeletal muscles of aging rats opens new avenues for the investigation of the role of Z-discs in age-related muscle dysfunction.

Outcomes from a large 10 year hepatitis C treatment programme in people who inject drugs: No effect of recent or former injecting drug use on treatment adherence or therapeutic response.

BACKGROUND AND AIMS: People who inject drugs (PWID) are historically viewed as having "difficult to treat" hepatitis C disease, with perceived inferior treatment adherence and outcomes, and concerns regarding reinfection risk. We evaluated for differences in treatment adherence and response to Peginterferon-alfa-2a/Ribavirin (Peg-IFNα/RBV) in a large urban cohort with and without a history of remote or recent injection drug use. METHODS: Patient data was retrospectively reviewed for 1000 consecutive patients-608 former (no injecting drug use for 6 months of therapy), 85 recent (injecting drug use within 6 months) PWID, and 307 non-drug users who were treated for chronic hepatitis C with Peg-IFNα/RBV. The groups were compared for baseline characteristics, treatment adherence, and outcome. RESULTS: There was no significant difference in treatment non-adherence between the groups (8.4% in PWID vs 6.8% in non-PWIDs; RR = 1.23, CI 0.76-1.99). The overall SVR rate in PWID (64.2%) was not different from non-PWIDs (60.9%) [RR = 1.05, 95% CI 0.95-1.17]. There was no significant difference in SVR rates between the groups controlling for genotype (48.4% vs 48.4% for genotype 1; 74.9 vs 73.3% for genotype 3). Former and recent PWID had similar adherence rates. CONCLUSIONS: PWID have comparable treatment adherence and SVR rates when compared to non-drug users treated with Peg-IFNα/RBV. These data support a public health strategy of HCV treatment and eradication in PWID in the DAA era.

Spontaneous Hepatitis B Seroclearance upon Development of Hepatocellular Carcinoma.

The spontaneous seroclearance of hepatitis B upon development of a hepatocellular carcinoma (HCC) is extremely rare. To date, there has been one published case series reporting hepatitis B seroconversion following HCC resection. We describe two novel cases of spontaneous hepatitis B seroclearance following the development of HCC, prior to resection. Following resection, specimens were HBsAg- and HBcAg-negative in both tumor and peritumor tissues. Although the precise mechanism of this is poorly understood, nonuniform integration of hepatitis B virus DNA within the liver could lead to selective tumorigenesis of HBsAg-producing cells, explaining the observed clearance of serum HBsAg with the development of HCC.

Mitochondrial and Metabolic Gene Expression in the Aged Rat Heart.

Aging is associated with a decline in cardiac function. Exercise intervention has been suggested as a way to improve this decrement. Age-related decline in cardiac function is associated with decreases in fatty acid oxidation, mitochondrial function, and AMP-activated protein kinase (AMPK) activity. The molecular mechanisms involved with age-related changes in mitochondrial function and substrate metabolism are poorly understood. We determined gene expression differences in hearts of Young (6 mo), Old (33 mo), and old exercise trained (Old + EXE) (34 mo) FBN rats, using Qiagen PCR arrays for Glucose, Fatty acid, and Mitochondrial metabolism. Old rats demonstrated decreased (p < 0.05) expression for key genes in fatty acid oxidation, mitochondrial function, and AMPK signaling. There were no differences in the expression of genes involved in glucose metabolism with age. These gene expression changes occurred prior to altered protein translation as we found no differences in the protein content of peroxisome proliferator activated receptor gamma, coactivators 1 alpha (PGC-1α), peroxisome proliferator activated receptor alpha (PPARα), and AMPKα2 between young and old hearts. Four months of exercise training did not attenuate the decline in the gene expression in aged hearts. Despite this lack of change in gene expression, exercise-trained rats demonstrated increased exercise capacity compared to their sedentary counterparts. Taken together, our results show that differential expression of genes associated with fatty acid metabolism, AMPK signaling and mitochondrial function decrease in the aging heart which may play a role in age-related declines in fatty acid oxidation, AMPK activity, and mitochondrial function in the heart.

Top-Down Targeted Proteomics Reveals Decrease in Myosin Regulatory Light-Chain Phosphorylation That Contributes to Sarcopenic Muscle Dysfunction.

Sarcopenia, the loss of skeletal muscle mass and function with advancing age, is a significant cause of disability and loss of independence in the elderly and thus, represents a formidable challenge for the aging population. Nevertheless, the molecular mechanism(s) underlying sarcopenia-associated muscle dysfunction remain poorly understood. In this study, we employed an integrated approach combining top-down targeted proteomics with mechanical measurements to dissect the molecular mechanism(s) in age-related muscle dysfunction. Top-down targeted proteomic analysis uncovered a progressive age-related decline in the phosphorylation of myosin regulatory light chain (RLC), a critical protein involved in the modulation of muscle contractility, in the skeletal muscle of aging rats. Top-down tandem mass spectrometry analysis identified a previously unreported bis-phosphorylated proteoform of fast skeletal RLC and localized the sites of decreasing phosphorylation to Ser14/15. Of these sites, Ser14 phosphorylation represents a previously unidentified site of phosphorylation in RLC from fast-twitch skeletal muscle. Subsequent mechanical analysis of single fast-twitch fibers isolated from the muscles of rats of different ages revealed that the observed decline in RLC phosphorylation can account for age-related decreases in the contractile properties of sarcopenic fast-twitch muscles. These results strongly support a role for decreasing RLC phosphorylation in sarcopenia-associated muscle dysfunction and suggest that therapeutic modulation of RLC phosphorylation may represent a new avenue for the treatment of sarcopenia.