Human physiomimetic model integrating microphysiological systems of the gut, liver, and brain for studies of neurodegenerative diseases.

Slow progress in the fight against neurodegenerative diseases (NDs) motivates an urgent need for highly controlled in vitro systems to investigate organ-organ- and organ-immune-specific interactions relevant for disease pathophysiology. Of particular interest is the gut/microbiome-liver-brain axis for parsing out how genetic and environmental factors contribute to NDs. We have developed a mesofluidic platform technology to study gut-liver-cerebral interactions in the context of Parkinson's disease (PD).

Gut-Liver Physiomimetics Reveal Paradoxical Modulation of IBD-Related Inflammation by Short-Chain Fatty Acids.

Although the association between the microbiome and IBD and liver diseases is known, the cause and effect remain elusive. By connecting human microphysiological systems of the gut, liver, and circulating Treg and Th17 cells, we created a multi-organ model of ulcerative colitis (UC) ex vivo. The approach shows microbiome-derived short-chain fatty acids (SCFAs) to either improve or worsen UC severity, depending on the involvement of effector CD4 T cells.

Interconnected Microphysiological Systems for Quantitative Biology and Pharmacology Studies.

Microphysiological systems (MPSs) are in vitro models that capture facets of in vivo organ function through use of specialized culture microenvironments, including 3D matrices and microperfusion. Here, we report an approach to co-culture multiple different MPSs linked together physiologically on re-useable, open-system microfluidic platforms that are compatible with the quantitative study of a range of compounds, including lipophilic drugs. We describe three different platform designs - "4-way", "7-way", and "10-way" - each accommodating a mixing chamber and up to 4, 7, or 10 MPSs.

Pediatric Miller Fisher Syndrome Complicating an Epstein-Barr Virus Infection.

Background: Miller Fisher syndrome, a variant of Guillain-Barré syndrome, is an acute inflammatory demyelinating polyradiculoneuropathy that may occur weeks after a bacterial or viral infection. Campylobacter jejuni and Haemophilus influenzae are frequently reported etiological agents.

Patient Description: We describe a boy with Miller Fisher syndrome following Epstein-002DBarr virus primary infectious mononucleosis.

Redox-mediated reciprocal regulation of SERCA and Na+-Ca2+ exchanger contributes to sarcoplasmic reticulum Ca2+ depletion in cardiac myocytes.

Myocardial failure is associated with increased oxidative stress and abnormal excitation-contraction coupling characterized by depletion of sarcoplasmic reticulum (SR) Ca(2+) stores and a reduction in Ca(2+)-transient amplitude. Little is known about the mechanisms whereby oxidative stress affects Ca(2+) handling and contractile function; however, reactive thiols may be involved. We used an in vitro cardiomyocyte system to test the hypothesis that short-term oxidative stress induces SR Ca(2+) depletion via redox-mediated regulation of sarcoendoplasmic reticulum Ca(2+)-ATPase (SERCA) and the sodium-Ca(2+) exchanger (NCX) and that this is associated with thiol oxidation.

The control of cardiomyocyte apoptosis via the beta-adrenergic signaling pathways.

Cardiomyocyte death resulting from apoptosis has been implicated in the evolution of heart failure. In this review, we focus on the concept that the cardiotoxicity of excessive sympathetic nervous system activity observed in heart failure is in part due to myocytes death by apoptosis. In vitro, high doses of norepinephrine induce adult cardiomyocyte apoptosis via 3-adrenergic receptor-coupled signaling pathways (PKA and Ca2+ entry-dependent mechanisms).

Externalization of endogenous annexin A5 participates in apoptosis of rat cardiomyocytes.

Objective: Annexins are Ca(2+)-dependent phospholipid binding proteins. Externalized annexin A5 has been recently suggested to have a proapoptotic effect. Our aim was to determine whether annexin A5, which is intracellular in cardiomyocytes, could be translocated and/or externalized and play a role during the apoptotic process.

beta1 integrins expression in adult rat ventricular myocytes and its role in the regulation of beta-adrenergic receptor-stimulated apoptosis.

We have shown that the stimulation of beta-adrenergic receptors (beta-AR) increases apoptosis in adult rat ventricular myocytes (ARVMs). Integrins, a family of alphabeta-heterodimeric cell surface receptors, are postulated to play a role in ventricular remodeling. Here, we show that norepinephrine (NE) increases beta1 integrins expression in ARVMs via the stimulation of alpha1-AR, not beta-AR.

Decreased efficiency of adenovirus-mediated gene transfer in aging cardiomyocytes.

Background: Aging is an independent risk factor for the development of cardiovascular disease. Clinical application of myocardial gene transfer may be best suited in the elderly. In vivo gene transfer by adenovirus is less efficient in aging myocardium.

Beta-adrenergic receptor-stimulated apoptosis in cardiac myocytes is mediated by reactive oxygen species/c-Jun NH2-terminal kinase-dependent activation of the mitochondrial pathway.

Stimulation of beta-adrenergic receptors (betaARs) causes apoptosis in adult rat ventricular myocytes (ARVMs). The role of reactive oxygen species (ROS) in mediating betaAR-stimulated apoptosis is not known. Stimulation of betaARs with norepinephrine (10 micromol/L) in the presence of prazosin (100 nmol/L) for 24 hours increased the number of apoptotic myocytes as determined by TUNEL staining by 3.

Reciprocal modulation of mitogen-activated protein kinases and mitogen-activated protein kinase phosphatase 1 and 2 in failing human myocardium.

Background: Mitogen-activated protein kinases (MAPKs), consisting of the ERK1/2, JNKs, and p38-kinase families, play a key role in the regulation of myocyte growth and apoptosis in vitro. The activity of MAPKs is regulated by dual-specificity MAPK phosphatases (MKPs). Because myocardial failure is associated with myocyte hypertrophy and apoptosis, MAPKs may play a pathophysiologic role in human myocardial failure.

Functional consequences of caspase activation in cardiac myocytes.

Cardiomyocyte apoptosis is present in many cardiac disease states, including heart failure and ischemic heart disease. Apoptosis is associated with the activation of caspases that mediate the cleavage of vital and structural proteins. However, the functional contribution of apoptosis to these conditions is not known.

Exaggerated left ventricular dilation and reduced collagen deposition after myocardial infarction in mice lacking osteopontin.

Osteopontin (OPN), an extracellular matrix protein, is expressed in the myocardium with hypertrophy and failure. We tested the hypothesis that OPN plays a role in left ventricular (LV) remodeling after myocardial infarction (MI). Accordingly, OPN expression and LV structural and functional remodeling were determined in wild-type (WT) and OPN knockout (KO) mice 4 weeks after MI.

Inhibition of protein phosphatase 1 induces apoptosis in neonatal rat cardiac myocytes: role of adrenergic receptor stimulation.

The mechanisms that regulate cardiac myocyte apoptosis are not well understood. To study the role of protein phosphatase 1 (PP1) and 2A (PP2A) in apoptosis, we exposed cultured neonatal rat cardiac myocytes to the phosphatase inhibitor okadaic acid (OA). Exposure (18 h) to 100 nM OA (a concentration which inhibits both PP1 and PP2A) decreased the number of adherent cells, caused genomic DNA fragmentation, and increased the percentage of apoptotic cells.

Altered beta-adrenergic signal transduction in nonfailing hypertrophied myocytes from Dahl salt-sensitive rats.

Desensitization of the beta-adrenergic receptor (beta-AR) response is well documented in hypertrophied hearts. We investigated whether beta-AR desensitization is also present at the cellular level in hypertrophied myocardium, as well as the physiological role of inhibitory G (G(i)) proteins and the L-type Ca(2+) channel in mediating beta-AR desensitization. Left ventricular (LV) myocytes were isolated from hypertrophied hearts of hypertensive Dahl salt-sensitive (DS) rats and nonhypertrophied hearts of normotensive salt-resistant (DR) rats.

Adrenergic overload and apoptosis in heart failure: implications for therapy.

Sympathetic nervous system activity to the myocardium is increased in patients with heart failure. It is now appreciated that norepinephrine (NE), the primary sympathetic neurotransmitter, can exert direct adverse effects on cardiac myocytes and might thereby contribute to pathological remodeling, a chronic process which leads to progressive left ventricular (LV) chamber dilation and loss of contractile function. The demonstration of apoptosis in failing human hearts has led to the thesis that continuing loss of viable myocytes is a mechanism for progressive myocardial failure.

Myocardial-directed overexpression of the human beta(1)-adrenergic receptor in transgenic mice.

The beta(1)-adrenergic receptor (AR) is the dominant subtype in non-failing and failing myocardium. beta(1)-AR signaling, by the endogenous neurotransmitter norepinephrine, is central to the regulation of myocardial contractility. In heart failure, the beta(1)-AR undergoes subtype-selective downregulation which may protect against the increased cardiac adrenergic drive associated with this pathophysiological state.

p38 mitogen-activated protein kinase pathway protects adult rat ventricular myocytes against beta -adrenergic receptor-stimulated apoptosis. Evidence for Gi-dependent activation.

We have shown that stimulation of beta-adrenergic receptors (beta-AR) by norepinephrine (NE) increases apoptosis in adult rat ventricular myocytes (ARVMs) via a cAMP-dependent mechanism that is antagonized by activation of G(i) protein. The family of mitogen-activated protein kinases (MAPKs) is involved in the regulation of cardiac myocyte growth and apoptosis. Here we show that beta-AR stimulation activates p38 kinase, c-jun N-terminal kinases (JNKs), and extracellular signal-regulated kinase (ERK1/2) in ARVMs.

Adrenergic regulation of myocardial apoptosis.

Increased sympathetic nerve activity to the myocardium is a central feature in patients with heart failure. Norepinephrine, the primary transmitter of the sympathetic nervous system, signals via binding to alpha- and beta-adrenergic receptors (AR) that are coupled to G-proteins. Pharmacologic studies of cardiac myocytes in vitro demonstrate that beta-AR can stimulate apoptosis.

Opposing effects of beta(1)- and beta(2)-adrenergic receptors on cardiac myocyte apoptosis : role of a pertussis toxin-sensitive G protein.

Background: beta-Adrenergic receptor (beta-AR) stimulation increases apoptosis in adult rat cardiac (ventricular) myocytes (ARVMs) via activation of adenylyl cyclase. beta(2)-ARs may couple to a G(i)-mediated signaling pathway that can oppose the actions of adenylyl cyclase.

Methods And Results: In ARVMs, beta-AR stimulation for 24 hours increased the number of apoptotic cells as measured by flow cytometry.

Myocardial osteopontin expression coincides with the development of heart failure.

To identify genes that are differentially expressed during the transition from compensated hypertrophy to failure, myocardial mRNA from spontaneously hypertensive rats (SHR) with heart failure (SHR-F) was compared with that from age-matched SHR with compensated hypertrophy (SHR-NF) and normotensive Wistar-Kyoto rats (WKY) by differential display reverse transcriptase-polymerase chain reaction. Characterization of a transcript differentially expressed in SHR-F yielded a cDNA with homology to the extracellular matrix protein osteopontin. Northern analysis showed low levels of osteopontin mRNA in left ventricular myocardium from WKY and SHR-NF but a markedly increased (approximately 10-fold) level in SHR-F.

Myocardial beta-adrenergic reactivity in pressure overload-induced cardiac hypertrophy in the rat.

The purpose of this study was to evaluate the changes in myocardial beta-adrenergic reactivity in animals undergoing a 4 week cardiac pressure-overload. Abdominal aortic constriction (AAC) or sham operation (sham) were performed in male Wistar rats, and 4 weeks later, isoprenaline dose-effects (chronotropic, inotropic and lusitropic properties) were studied after pithing. Noradrenaline (NA) and adrenaline (A) concentrations and NA turn-over index (DHPG /NE ratio) were evaluated in heart ventricles, while beta-adrenoceptor characteristics in ventricle homogenates and slices with [125I]iodocyanopindolol and the beta (1)/beta (2)-adrenoceptor ratio were estimated.

Norepinephrine stimulates apoptosis in adult rat ventricular myocytes by activation of the beta-adrenergic pathway.

Background: Myocardial sympathetic activity is increased in heart failure. We tested the hypothesis that norepinephrine (NE) stimulates apoptosis in adult rat ventricular myocytes in vitro.

Methods And Results: Myocytes were exposed to NE alone (10 micromol/L), NE+propranolol (2 micromol/L), NE+prazosin (0.

Myocardial beta-adrenergic reactivity in volume overload-induced cardiac hypertrophy in the rat.

The purpose of this study was to evaluate the changes in myocardial beta-adrenergic reactivity in animals undergoing a 4 week cardiac volume overload. Aortocaval shunt (ACS) or sham operation (sham) were performed in male Wistar rats, and 4 weeks later, isoproterenol dose-effects (chronotropic, inotropic and lusitropic properties) were studied after pithing. Noradrenaline (NA) and adrenaline (A) concentrations and NA turn-over index were evaluated in plasma and heart ventricles, while beta-adrenoceptor characteristics in ventricle homogenates and slices with [125I]iodocyanopindolol, and the beta(1)/beta(2)-adrenoceptor ratio were estimated.