Accelerated cardiac remodeling in desmoplakin transgenic mice in response to endurance exercise is associated with perturbed Wnt/ß-catenin signaling.

Arrhythmogenic ventricular cardiomyopathy (AVC) is a frequent underlying cause for arrhythmias and sudden cardiac death especially during intense exercise. The mechanisms involved remain largely unknown. The purpose of this study was to investigate how chronic endurance exercise contributes to desmoplakin (DSP) mutation-induced AVC pathogenesis. Transgenic mice with overexpression of desmoplakin, wild-type (Tg-DSP(WT)), or the R2834H mutant (Tg-DSP(R2834H)) along with control nontransgenic (NTg) littermates were kept sedentary or exposed to a daily running regimen for 12 wk. Cardiac function and morphology were analyzed using echocardiography, electrocardiography, histology, immunohistochemistry, RNA, and protein analysis. At baseline, 4-wk-old mice from all groups displayed normal cardiac function. When subjected to exercise, all mice retained normal cardiac function and left ventricular morphology; however, Tg-DSP(R2834H) mutants displayed right ventricular (RV) dilation and wall thinning, unlike NTg and Tg-DSP(WT). The Tg-DSP(R2834H) hearts demonstrated focal fat infiltrations in RV and cytoplasmic aggregations consisting of desmoplakin, plakoglobin, and connexin 43. These aggregates coincided with disruption of the intercalated disks, intermediate filaments, and microtubules. Although Tg-DSP(R2834H) mice already displayed high levels of p-GSK3-ß(Ser9) and p-AKT1(Ser473) under sedentary conditions, decrease of nuclear GSK3-ß and AKT1 levels with reduced p-GSK3-ß(Ser9), p-AKT1(Ser473), and p-AKT1(Ser308) and loss of nuclear junctional plakoglobin was apparent after exercise. In contrast, Tg-DSP(WT) showed upregulation of p-AKT1(Ser473), p-AKT1(Ser308), and p-GSK3-ß(Ser9) in response to exercise. Our data suggest that endurance exercise accelerates AVC pathogenesis in Tg-DSP(R2834H) mice and this event is associated with perturbed AKT1 and GSK3-ß signaling. Our study suggests a potential mechanism-based approach to exercise management in patients with AVC.

Surface-Growing Communities of Pseudomonas aeruginosa Exhibit Distinct Alkyl Quinolone Signatures.

A cascade of events leads to the development of microbial biofilm communities that are thought to be responsible for over 80% of infections in humans. However, not all surface-growing bacteria reside in a stationary biofilm state. Here, we have employed confocal Raman microscopy to analyze and compare variations in the alkyl quinolone (AQ) family of molecules during the transition between surface-attached motile-swarming and stationary biofilm communities. The AQs have been established previously as important to Pseudomonas aeruginosa biofilms, interspecies competition, and virulence. The AQ Pseudomonas quinolone signal (PQS) is also a known quorum-sensing signal. We detail spatial identification of AQ, PQS, and 2-alkyl-4-hydroxyquinoline N-oxide (AQNO) metabolites in both swarm and biofilm communities. We find that AQNO metabolites are abundant signatures in active swarming communities.

Disturbance in Z-disk mechanosensitive proteins induced by a persistent mutant myopalladin causes familial restrictive cardiomyopathy.

BACKGROUND: Familial restrictive cardiomyopathy (FRCM) has a poor prognosis due to diastolic dysfunction and restrictive physiology (RP). Myocardial stiffness, with or without fibrosis, underlie RP, but the mechanism(s) of restrictive remodeling is unclear. Myopalladin (MYPN) is a messenger molecule that links structural and gene regulatory molecules via translocation from the Z-disk and I-bands to the nucleus in cardiomyocytes. Expression of N-terminal MYPN peptide results in severe disruption of the sarcomere. OBJECTIVES: The aim was to study a nonsense MYPN-Q529X mutation previously identified in the FRCM family in an animal model to explore the molecular and pathogenic mechanisms of FRCM. METHODS: Functional (echocardiography, cardiac magnetic resonance [CMR] imaging, electrocardiography), morphohistological, gene expression, and molecular studies were performed in knock-in heterozygote (Mypn(WT/Q526X)) and homozygote mice harboring the human MYPN-Q529X mutation. RESULTS: Echocardiographic and CMR imaging signs of diastolic dysfunction with preserved systolic function were identified in 12-week-old Mypn(WT/Q526X) mice. Histology revealed interstitial and perivascular fibrosis without overt hypertrophic remodeling. Truncated Mypn(Q526X) protein was found to translocate to the nucleus. Levels of total and nuclear cardiac ankyrin repeat protein (Carp/Ankrd1) and phosphorylation of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (Erk1/2), Erk1/2, Smad2, and Akt were reduced. Up-regulation was evident for muscle LIM protein (Mlp), desmin, and heart failure (natriuretic peptide A [Nppa], Nppb, and myosin heavy chain 6) and fibrosis (transforming growth factor beta 1, alpha-smooth muscle actin, osteopontin, and periostin) markers. CONCLUSIONS: Heterozygote Mypn(WT/Q526X) knock-in mice develop RCM due to persistence of mutant Mypn(Q526X) protein in the nucleus. Down-regulation of Carp and up-regulation of Mlp and desmin appear to augment fibrotic restrictive remodeling, and reduced Erk1/2 levels blunt a hypertrophic response in Mypn(WT/Q526X) hearts.

Effects of influenza immunization on humoral and cellular alloreactivity in humans.

BACKGROUND: Alloreactive T cells and anti-human leukocyte antigen antibodies mediate transplant injury. Environmental exposures, including vaccinations, may activate the alloimmune repertoire leading to accelerated allograft injury. To test whether vaccination impacts human alloimmunity, we analyzed humoral and cellular immune reactivity in subjects undergoing influenza vaccination. METHODS: We serially obtained blood samples from 30 healthy subjects and 8 kidney and 9 lung transplant recipients who received influenza vaccination, and from 20 healthy unvaccinated controls. We measured cellular and humoral anti-influenza responses, anti-human leukocyte antigen antibodies, and alloreactive T-cell immunity (interferon-gamma ELISPOT) at 0, 2, 4, and 12 weeks after vaccination. RESULTS: Vaccination induced influenza-reactive humoral and cellular responses in control subjects and in transplant recipients. Only two of 30 vaccinated volunteers developed new alloantibodies, but none of the transplant patients. Vaccination also specifically and significantly augmented cellular alloimmunity based on reactivity to a panel of stimulators in both healthy subjects and in transplant recipients within 4 weeks of vaccination. The enhanced cellular alloresponse waned toward prevaccine levels by week 12. CONCLUSION: Our findings newly demonstrate that influenza vaccination can have a significant impact on the potency of the alloimmune repertoire. Because the strength of the alloresponse influences long-term graft function, our results suggest that further investigation of alloimmune monitoring after vaccination is needed.