Transient Receptor Potential Canonical 5 (TRPC5): Regulation of Heart Rate and Protection against Pathological Cardiac Hypertrophy

TRPC5 is a non-selective cation channel that is expressed in cardiomyocytes, but there is a lack of knowledge of its (patho)physiological role in vivo. Here, we examine the role of TRPC5 on cardiac function under basal conditions and during cardiac hypertrophy. Cardiovascular parameters were assessed in wild-type (WT) and global TRPC5 knockout (KO) mice. Despite no difference in blood pressure or activity, heart rate was significantly reduced in TRPC5 KO mice. Echocardiography imaging revealed an increase in stroke volume, but cardiac contractility was unaffected. The reduced heart rate persisted in isolated TRPC5 KO hearts, suggesting changes in basal cardiac pacing. Heart rate was further investigated by evaluating the reflex change following drug-induced pressure changes. The reflex bradycardic response following phenylephrine was greater in TRPC5 KO mice but the tachycardic response to SNP was unchanged, indicating an enhancement in the parasympathetic control of the heart rate. Moreover, the reduction in heart rate to carbachol was greater in isolated TRPC5 KO hearts. To evaluate the role of TRPC5 in cardiac pathology, mice were subjected to abdominal aortic banding (AAB). An exaggerated cardiac hypertrophy response to AAB was observed in TRPC5 KO mice, with an increased expression of hypertrophy markers, fibrosis, reactive oxygen species, and angiogenesis. This study provides novel evidence for a direct effect of TRPC5 on cardiac function. We propose that (1) TRPC5 is required for maintaining heart rate by regulating basal cardiac pacing and in response to pressure lowering, and (2) TRPC5 protects against pathological cardiac hypertrophy.

Indo-Pacific Walker circulation drove Pleistocene African aridification

Today, the eastern African hydroclimate is tightly linked to fluctuations in the zonal atmospheric Walker circulation^1,2. A growing body of evidence indicates that this circulation shaped hydroclimatic conditions in the Indian Ocean region also on much longer, glacial-interglacial timescales^3-5, following the development of Pacific Walker circulation around 2.2-2.0 million years ago (Ma)^6,7. However, continuous long-term records to determine the timing and mechanisms of Pacific-influenced climate transitions in the Indian Ocean have been unavailable. Here we present a seven-million-year-long record of wind-driven circulation of the tropical Indian Ocean, as recorded in Mozambique Channel Throughflow (MCT) flow-speed variations. We show that the MCT flow speed was relatively weak and steady until 2.1 ± 0.1 Ma, when it began to increase, coincident with the intensification of the Pacific Walker circulation^6,7. Strong increases during glacial periods, which reached maxima after the Mid-Pleistocene Transition (0.9-0.64 Ma; ref. ⁸), were punctuated by weak flow speeds during interglacial periods. We provide a mechanism explaining that increasing MCT flow speeds reflect synchronous development of the Indo-Pacific Walker cells that promote aridification in Africa. Our results suggest that after about 2.1 Ma, the increasing aridification is punctuated by pronounced humid interglacial periods. This record will facilitate testing of hypotheses of climate-environmental drivers for hominin evolution and dispersal.

Nitric Oxide Modulates Metabolic Remodeling in Inflammatory Macrophages through TCA Cycle Regulation and Itaconate Accumulation

Classical activation of macrophages (M(LPS+IFNγ)) elicits the expression of inducible nitric oxide synthase (iNOS), generating large amounts of NO and inhibiting mitochondrial respiration. Upregulation of glycolysis and a disrupted tricarboxylic acid (TCA) cycle underpin this switch to a pro-inflammatory phenotype. We show that the NOS cofactor tetrahydrobiopterin (BH4) modulates IL-1β production and key aspects of metabolic remodeling in activated murine macrophages via NO production. Using two complementary genetic models, we reveal that NO modulates levels of the essential TCA cycle metabolites citrate and succinate, as well as the inflammatory mediator itaconate. Furthermore, NO regulates macrophage respiratory function via changes in the abundance of critical N-module subunits in Complex I. However, NO-deficient cells can still upregulate glycolysis despite changes in the abundance of glycolytic intermediates and proteins involved in glucose metabolism. Our findings reveal a fundamental role for iNOS-derived NO in regulating metabolic remodeling and cytokine production in the pro-inflammatory macrophage.

l-Phenylalanine Restores Vascular Function in Spontaneously Hypertensive Rats Through Activation of the GCH1-GFRP Complex

•

Tetrahydrobiopterin is an essential cofactor for NO production.

•

Limitation of endogenous tetrahydrobiopterin reduces NO bioavailability, enhances oxidative stress, and impairs vascular function.

•

Orally supplemented tetrahydrobiopterin has therapeutic challenges because it is rapidly oxidized in vivo.

•

Here, the authors demonstrate that l-phenylalanine, when administered orally, raises vascular tetrahydrobiopterin, restores NO, reduces superoxide, and enhances vascular function in spontaneously hypertensive rats.

•

This effect is achieved by activation of a protein complex (GCH1-GFRP) involved in the biosynthesis of tetrahydrobiopterin.

•

Activation of this protein complex by l-phenylalanine or its analogues represents a novel therapeutic target for vascular disorders underpinned by reduced NO bioavailability.

Reduced nitric oxide (NO) bioavailability correlates with impaired cardiovascular function. NO is extremely labile and has been challenging to develop as a therapeutic agent. However, NO bioavailability could be enhanced by pharmacologically targeting endogenous NO regulatory pathways. Tetrahydrobiopterin, an essential cofactor for NO production, is synthesized by GTP cyclohydrolase-1 (GCH1), which complexes with GCH1 feedback regulatory protein (GFRP). The dietary amino acid l-phenylalanine activates this complex, elevating vascular BH₄. Here, the authors demonstrate that l-phenylalanine administration restores vascular function in a rodent model of hypertension, suggesting the GCH1-GFRP complex represents a rational therapeutic target for diseases underpinned by endothelial dysfunction.

In vivo pharmacological activity and biodistribution of S-nitrosophytochelatins after intravenous and intranasal administration in mice

S-nitrosophytochelatins (SNOPCs) are novel analogues of S-nitrosoglutathione (GSNO) with the advantage of carrying varying ratios of S-nitrosothiol (SNO) moieties per molecule. Our aim was to investigate the in vivo pharmacological potency and biodistribution of these new GSNO analogues after intravenous (i.v.) and intranasal (i.n.) administration in mice. SNOPCs with either two or six SNO groups and GSNO were synthesized and characterized for purity. Compounds were administered i.v. or i.n. at 1 μmol NO/kg body weight to CD-1 mice. Blood pressure was measured and biodistribution studies of total nitrate and nitrite species (NOx) and phytochelatins were performed after i.v. administration. At equivalent doses of NO, it was observed that SNOPC-6 generated a rapid and significantly greater reduction in blood pressure (∼60% reduction compared to saline) whereas GSNO and SNOPC-2 only achieved a 30-35% decrease. The reduction in blood pressure was transient and recovered to baseline levels within ∼2 min for all compounds. NOx species were transiently elevated (over 5 min) in the plasma, lung, heart and liver. Interestingly, a size-dependent phytochelatin accumulation was observed in several tissues including the heart, lungs, kidney, brain and liver. Biodistribution profiles of NOx were also obtained after i.n. administration, showing significant lung retention of NOx over 15 min with minor systemic increases observed from 5 to 15 min. In summary, this study has revealed interesting in vivo pharmacological properties of SNOPCs, with regard to their dramatic hypotensive effects and differing biodistribution patterns following two different routes of administration.

Endothelial cell tetrahydrobiopterin deficiency attenuates LPS-induced vascular dysfunction and hypotension

Overproduction of nitric oxide (NO) is thought to be a key mediator of the vascular dysfunction and severe hypotension in patients with endotoxaemia and septic shock. The contribution of NO produced directly in the vasculature by endothelial cells to the hypotension seen in these conditions, vs. the broader systemic increase in NO, is unclear. To determine the specific role of endothelium derived NO in lipopolysaccharide (LPS)-induced vascular dysfunction we administered LPS to mice deficient in endothelial cell tetrahydrobiopterin (BH4), the essential co-factor for NO production by NOS enzymes. Mice deficient in endothelial BH4 production, through loss of the essential biosynthesis enzyme Gch1 (Gch1(fl/fl)Tie2cre mice) received a 24hour challenge with LPS or saline control. In vivo LPS treatment increased vascular GTP cyclohydrolase and BH4 levels in aortas, lungs and hearts, but this increase was significantly attenuated in Gch1(fl/fl)Tie2cre mice, which were also partially protected from the LPS-induced hypotension. In isometric tension studies, in vivo LPS treatment reduced the vasoconstriction response and impaired endothelium-dependent and independent vasodilatations in mesenteric arteries from wild-type mice, but not in Gch1(fl/fl)Tie2cre mesenteric arteries. Ex vivo LPS treatment decreased vasoconstriction response to phenylephrine in aortic rings from wild-type and not in Gch1(fl/fl)Tie2cre mice, even in the context of significant eNOS and iNOS upregulation. These data provide direct evidence that endothelial cell NO has a significant contribution to LPS-induced vascular dysfunction and hypotension and may provide a novel therapeutic target for the treatment of systemic inflammation and patients with septic shock.

Validating the GTP-cyclohydrolase 1-feedback regulatory complex as a therapeutic target using biophysical and in vivo approaches

BACKGROUND AND PURPOSE

6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4 ) is an essential cofactor for nitric oxide biosynthesis. Substantial clinical evidence indicates that intravenous BH4 restores vascular function in patients. Unfortunately, oral BH4 has limited efficacy. Therefore, orally bioavailable pharmacological activators of endogenous BH4 biosynthesis hold significant therapeutic potential. GTP-cyclohydrolase 1 (GCH1), the rate limiting enzyme in BH4 synthesis, forms a protein complex with GCH1 feedback regulatory protein (GFRP). This complex is subject to allosteric feed-forward activation by L-phenylalanine (L-phe). We investigated the effects of L-phe on the biophysical interactions of GCH1 and GFRP and its potential to alter BH4 levels in vivo.

EXPERIMENTAL APPROACH

Detailed characterization of GCH1-GFRP protein-protein interactions were performed using surface plasmon resonance (SPR) with or without L-phe. Effects on systemic and vascular BH4 biosynthesis in vivo were investigated following L-phe treatment (100 mg·kg(-1) , p.o.).

KEY RESULTS

GCH1 and GFRP proteins interacted in the absence of known ligands or substrate but the presence of L-phe doubled maximal binding and enhanced binding affinity eightfold. Furthermore, the complex displayed very slow association and dissociation rates. In vivo, L-phe challenge induced a sustained elevation of aortic BH4 , an effect absent in GCH1(fl/fl)-Tie2Cre mice.

CONCLUSIONS AND IMPLICATIONS

Biophysical data indicate that GCH1 and GFRP are constitutively bound. In vivo, data demonstrated that L-phe elevated vascular BH4 in an endothelial GCH1 dependent manner. Pharmacological agents which mimic the allosteric effects of L-phe on the GCH1-GFRP complex have the potential to elevate endothelial BH4 biosynthesis for numerous cardiovascular disorders.

Blockade or deletion of transient receptor potential vanilloid 4 (TRPV4) is not protective in a murine model of sepsis

Sepsis is a systemic inflammatory response triggered by microbial infection that can cause cardiovascular collapse, insufficient tissue perfusion and multi-organ failure. The cation channel transient receptor potential vanilloid 4 (TRPV4) is expressed in vascular endothelium and causes vasodilatation, but excessive TRPV4 activation leads to profound hypotension and circulatory collapse - key features of sepsis pathogenesis. We hypothesised that loss of TRPV4 signaling would protect against cardiovascular dysfunction in a mouse model of sepsis (endotoxaemia). Multi-parameter monitoring of conscious systemic haemodynamics (by radiotelemetry probe), mesenteric microvascular blood flow (laser speckle contrast imaging) and blood biochemistry (iSTAT blood gas analysis) was carried out in wild type (WT) and TRPV4 knockout (KO) mice. Endotoxaemia was induced by a single intravenous injection of lipopolysaccharide (LPS; 12.5 mg/kg) and systemic haemodynamics monitored for 24 h. Blood flow recording was then conducted under terminal anaesthesia after which blood was obtained for haematological/biochemical analysis. No significant differences were observed in baseline haemodynamics or mesenteric blood flow. Naïve TRPV4 KO mice were significantly acidotic relative to WT counterparts. Following induction of sepsis, all mice became significantly hypotensive, though there was no significant difference in the degree of hypotension between TRPV4 WT and KO mice. TRPV4 KO mice exhibited a higher sepsis severity score. While septic WT mice became significantly hypernatraemic relative to the naïve state, this was not observed in septic KO mice. Mesenteric blood flow was inhibited by topical application of the TRPV4 agonist GSK1016790A in naïve WT mice, but enhanced 24 h following LPS injection. Contrary to the initial hypothesis, loss of TRPV4 signaling (either through gene deletion or pharmacological antagonism) did not attenuate sepsis-induced cardiovascular dysfunction: in fact, pathology appeared to be modestly exaggerated in mice lacking TRPV4. Local targeting of TRPV4 signalling may be more beneficial than global inhibition in sepsis treatment.

Quantification of microcirculatory blood flow: a sensitive and clinically relevant prognostic marker in murine models of sepsis

Sepsis and sepsis-associated multiorgan failure represent the major cause of mortality in intensive care units worldwide. Cardiovascular dysfunction, a key component of sepsis pathogenesis, has received much research interest, although research translatability remains severely limited. There is a critical need for more comprehensive preclinical sepsis models, with more clinically relevant end points, such as microvascular perfusion. The purpose of this study was to compare microcirculatory blood flow measurements, using a novel application of laser speckle contrast imaging technology, with more traditional hemodynamic end points, as part of a multiparameter monitoring system in preclinical models of sepsis. Our aim, in measuring mesenteric blood flow, was to increase the prognostic sensitivity of preclinical studies. In two commonly used sepsis models (cecal ligation and puncture, and lipopolysaccharide), we demonstrate that blood pressure and cardiac output are compromised postsepsis, but subsequently stabilize over the 24-h recording period. In contrast, mesenteric blood flow continuously declines in a time-dependent manner and in parallel with the development of metabolic acidosis and organ dysfunction. Importantly, these microcirculatory perturbations are reversed by fluid resuscitation, a mainstay intervention associated with improved outcome in patients. These data suggest that global hemodynamics are maintained at the expense of the microcirculation and are, therefore, not sufficiently predictive of outcome. We demonstrate that microcirculatory blood flow is a more sensitive biomarker of sepsis syndrome progression and believe that incorporation of this biomarker into preclinical models will facilitate sophisticated proof-of-concept studies for novel sepsis interventions, providing more robust data on which to base future clinical trials.

Overexpression of GTP cyclohydrolase 1 feedback regulatory protein is protective in a murine model of septic shock

Overproduction of nitric oxide (NO) by inducible NO synthase contributes toward refractory hypotension, impaired microvascular perfusion, and end-organ damage in septic shock patients. Tetrahydrobiopterin (BH4) is an essential NOS cofactor. GTP cyclohydrolase 1 (GCH1) is the rate-limiting enzyme for BH4 biosynthesis. Under inflammatory conditions, GCH1 activity and hence BH4 levels are increased, supporting pathological NOS activity. GCH1 activity can be controlled through allosteric interactions with GCH1 feedback regulatory protein (GFRP). We investigated whether overexpression of GFRP can regulate BH4 and NO production and attenuate cardiovascular dysfunction in sepsis. Sepsis was induced in mice conditionally overexpressing GFRP and wild-type littermates by cecal ligation and puncture. Blood pressure was monitored by radiotelemetry, and mesenteric blood flow was quantified by laser speckle contrast imaging. Blood biochemistry data were obtained using an iSTAT analyzer, and BH4 levels were measured in plasma and tissues by high-performance liquid chromatography. Increased BH4 and NO production and hypotension were observed in all mice, but the extents of these pathophysiological changes were attenuated in GFRP OE mice. Perturbations in blood biochemistry were similarly attenuated in GFRP OE compared with wild-type controls. These results suggest that GFRP overexpression regulates GCH1 activity during septic shock, which in turn limits BH4 bioavailability for iNOS. We conclude that the GCH1-GFRP axis is a critical regulator of BH4 and NO production and the cardiovascular derangements that occur in septic shock.

The regulation of vascular tetrahydrobiopterin bioavailability

6R l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for several enzymes including phenylalanine hydroxylase and the nitric oxide synthases (NOS). Oral supplementation of BH4 has been successfully employed to treat subsets of patients with hyperphenylalaninaemia. More recently, research efforts have focussed on understanding whether BH4 supplementation may also be efficacious in cardiovascular disorders that are underpinned by reduced nitric oxide bioavailability. Whilst numerous preclinical and clinical studies have demonstrated a positive association between enhanced BH4 and vascular function, the efficacy of orally administered BH4 in human cardiovascular disease remains unclear. Furthermore, interventions that limit BH4 bioavailability may provide benefit in diseases where nitric oxide over production contributes to pathology. This review describes the pathways involved in BH4 bio-regulation and discusses other endogenous mechanisms that could be harnessed therapeutically to manipulate vascular BH4 levels.

Abstract P2-05-06: Quantitative measurement of HER2 expression in breast cancers: comparison with “real world” HER2 testing in a multi-center Collaborative Biomarker Study (CBS) and correlation with clinicopathological features

Background: Accurate determination of HER2 status is critical in determining appropriate therapy for breast cancer patients. The HERmark® assay is a novel method to quantitatively measure HER2 total protein expression (H2T) in breast cancer. In this study, we compared HERmark H2T with central laboratory HER2 retesting and local (site reported) HER2 testing of formalin-fixed, paraffin-embedded (FFPE) breast cancer tissues. The quantitative total HER2 measurements (H2T) by HERmark and results of local HER2 tests were correlated with tumor pathohistological characteristics and overall survival of breast cancer patients.

Methods: 232 FFPE breast cancer tissues were provided by 11 CBS study sites for HER2 testing by the HERmark assay and central laboratory IHC re-testing performed in blinded fashion. Local HER2 immunohistochemistry and/or fluorescence in situ hybridization (FISH) results and valid HERmark H2T and central HER2 IHC results were obtained in 192 cases for analysis.

Results: H2T showed a significant correlation with central HER2 IHC staining intensity (P < 0.0001). The concordance rates of positive and negative HERmark status (excluding equivocal) with those of local HER2 status determined by the CBS sites, and with those of central HER2 IHC status were 84% (Kappa = 0.68) and 96% (Kappa = 0.91), respectively. Higher H2T levels significantly correlated with higher tumor grade (p = 0.007) and negative ER/PR status (p = 0.002). Twenty-six (14%) cases showed discordant (conversion of negative and positive) results between local HER2 status and HERmark status. Of the discordant cases, HERmark significantly agreed with H-score of central HER2 IHC retesting (p = 0.014), as compared with local HER2 status. The concordant negative group (local HER2 negative/H2T low) demonstrated better overall survival (OS) (HR = 0.198, p = 0.0001), compared to that of concordant positive group (local HER2 positive/H2T high). The concordant negative group also showed better OS than that of discordant local HER2 negative/H2T high group (HR = 0.065, p = 0.0003), but showed no significant difference in OS as compared to that of discordant local HER2 positive/H2T low group (HR = 1.774, p = 0.499).). In 24 cases (13%) considered to be “triple negative” by local HER2, ER and PR testing, HERmark re-classified 4 cases (17%) as HER2 positive.

Conclusions: H2T by HERmark yields a continuum of quantitative HER2 protein measurements that shows an excellent correlation with central HER2 IHC retesting and confirms the known correlations between HER2 expression with tumor grade and ER/PR status. OS results of concordant HER2 positive or negative groups (between local HER2 testing and HERmark H2T) confirmed that HER2 positive patients (excluding adjuvant trastuzumab therapy) have worse OS than patients with HER2 negative disease. However, in the HERmark and local HER2 discordant groups, OS appeared to track better with H2T by HERmark and not with the local HER2 status. Novel quantitative HER2 measurements may identify patients with false (+) and (−) HER2 status by local HER2 testing and may provide added clinical value to routine “real world” HER2 testing.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-05-06.

Genetic and pharmacological inhibition of dimethylarginine dimethylaminohydrolase 1 is protective in endotoxic shock

OBJECTIVE

The overproduction of vascular NO contributes toward the circulatory collapse observed in patients with septic shock. Dimethylarginine dimethylaminohydrolase (DDAH), which has 2 isoforms, metabolizes asymmetrically methylated arginines (asymmetric mono- or di-methylarginine), endogenously produced NO synthase inhibitors. We wished to investigate whether reducing DDAH1 activity, using genetic and pharmacological approaches, is protective during lipopolysaccharide-induced endotoxic shock.

METHODS AND RESULTS

Experiments were conducted in DDAH1 heterozygous knockout mice (DDAH1(+/-)) or naive rats treated with a synthetic pharmacological DDAH inhibitor (L-257). We demonstrate for the first time that L-257 is DDAH1 selective using recombinant human DDAH proteins. DDAH1 mRNA was expressed in aortic but not macrophage cDNA, and consistent with this expression profile, L-257 selectively inhibited NO production from lipopolysaccharide-treated aorta but not macrophages, in culture. Conscious and anesthetized cardiovascular hemodynamics were monitored using implanted radiotelemetry devices or invasive catheters, respectively. Lipopolysaccharide was administered intravenously to model endotoxemia, and all animals presented with circulatory shock. DDAH1(+/-) mice or L-257-treated rats displayed attenuation in the rate of developed hypotension compared with wild-type littermates or vehicle control animals, respectively.

CONCLUSIONS

Pharmacological and genetic reduction of DDAH1 activity is protective against the vascular changes observed during endotoxic shock.

Phase I study of axitinib combined with paclitaxel, docetaxel or capecitabine in patients with advanced solid tumours

Background:

Axitinib, a potent and selective second-generation inhibitor of vascular endothelial growth factor receptors, enhanced the efficacy of chemotherapy in human xenograft tumour models. This phase I study investigated the safety, tolerability, pharmacokinetics and antitumour activity of axitinib combined with chemotherapy.

Methods:

A total of 42 patients with advanced solid tumours received a continuous axitinib starting dose of 5 mg twice daily (b.i.d.) plus paclitaxel (90 mg m^–2 weekly), docetaxel (100 mg m^–2 every 3 weeks) or capecitabine (1000 or 1250 mg m^–2 b.i.d., days 1–14).

Results:

Common treatment-related adverse events across all cohorts were nausea (45.2%), hypertension (45.2%), fatigue (42.9%), diarrhoea (38.1%), decreased appetite (33.3%) and hand–foot syndrome (31.0%). There was one complete response, nine partial responses and seven patients with stable disease. Ten patients (23.8%) remained on therapy for >8 months. Paclitaxel and capecitabine pharmacokinetics were similar in the absence or presence of axitinib, but docetaxel exposure was increased in the presence of axitinib. Axitinib pharmacokinetics were similar in the absence or presence of co-administered agents.

Conclusions:

Axitinib combined with paclitaxel or capecitabine was well tolerated; no additive increase in toxicities was observed. Antitumour activity was observed for each treatment regimen and across multiple tumour types.

An exploratory study of sunitinib plus paclitaxel as first-line treatment for patients with advanced breast cancer

Background: Sunitinib has shown single-agent activity in patients with previously treated metastatic breast cancer (MBC). We investigated the safety of the combination of sunitinib and paclitaxel in an exploratory study of patients with locally advanced or MBC.

Methods: Patients received oral sunitinib 25 mg/day (with escalation to 37.5 mg/day as tolerated) on a continuous daily dosing schedule and paclitaxel 90 mg/m² on days 1, 8, and 15 of each 28-day cycle. Study endpoints included safety (primary endpoint), pharmacokinetics, and antitumor activity.

Results: Twenty-two patients were enrolled. The most frequent adverse events (AEs) were fatigue/asthenia (77%), dysgeusia (68%), and diarrhea (64%). Grade 3 AEs included neutropenia (43%), fatigue/asthenia (27%), neuropathy (18%), and diarrhea (14%). No drug–drug interaction was observed on the basis of pharmacokinetic analysis. Of 18 patients with measurable disease at baseline, 7 (38.9%) achieved objective responses (including 2 complete and 5 partial responses). Clinical responses were observed in three of nine patients with triple-negative receptor status (estrogen receptor negative, progesterone receptor negative, and human epidermal growth factor receptor-2 negative).

Conclusions: These data indicate that sunitinib and paclitaxel in combination are well tolerated in patients with locally advanced or MBC. No drug–drug interaction was detected and there was preliminary evidence of antitumor activity.

Cortical event-related potentials in preclinical familial Alzheimer disease

OBJECTIVE

To define changes in cortical function in persons inheriting familial Alzheimer disease (FAD) mutations before the onset of cognitive decline.

METHODS

Twenty-six subjects with a family history of FAD were divided into 2 subgroups according to genotype (FAD mutation carriers, n = 15; FAD noncarriers, n = 11). Subjects were given standardized tests of cognitive function and the Clinical Dementia Rating scale (CDR). Sensory (P50, N100, P200) and cognitive (N200, P300) event-related potentials were recorded during an auditory discrimination task. Amplitudes and latencies of cortical potentials were compared among FAD mutation carriers and noncarriers.

RESULTS

FAD mutation carriers and noncarriers did not significantly differ in age or on measures of cognitive function, but FAD carriers had a greater incidence of 0.5 CDR scores (1/10 noncarriers, 5/15 carriers). Relative to noncarriers, FAD mutation carriers had significantly longer latencies of the N100, P200, N200, and P300 components, and smaller slow wave amplitudes. Subanalyses of subjects having CDR scores of 0.0 also showed latency increases in FAD mutation carriers.

CONCLUSIONS

Auditory sensory and cognitive cortical potentials in persons with familial Alzheimer disease (FAD) mutations are abnormal approximately 10 years before dementia will be manifest. Longer event-related potential latencies suggest slowing of cortical information processing in FAD mutation carriers.

Investigation of sensory neurogenic components in a bleomycin-induced scleroderma model using transient receptor potential vanilloid 1 receptor- and calcitonin gene-related peptide-knockout mice

OBJECTIVE

Along with their classic afferent function (nociception), capsaicin-sensitive transient receptor potential vanilloid 1 (TRPV1) receptor-expressing sensory nerve terminals exert local and systemic efferent activities. Activation of TRPV1 causes sensory neuropeptide release, which modulates the inflammation process. The aim of the present study was to examine the role of this modulatory role of TRPV1 receptor and that of calcitonin gene-related peptide (CGRP) in bleomycin-induced scleroderma, using transgenic mice.

METHODS

Cutaneous sclerosis was induced with daily subcutaneous injections of bleomycin for 30 days. Control groups were treated with phosphate buffered saline (PBS). TRPV1 receptor gene-deficient (TRPV1(-/-)) mice and CGRP-knockout (CGRP(-/-)) mice and their wild-type (WT) counterparts were investigated. A composite sclerosis score was calculated on the basis of thickening, leukocyte infiltration, and the amount/orientation of collagen bundles. Dermal thickness and the number of alpha-smooth muscle actin (alpha-SMA)-positive cells were also determined. The quantity of the collagen-specific amino acid hydroxyproline was measured by spectrophotometry.

RESULTS

Bleomycin treatment induced marked cutaneous thickening and fibrosis compared with that observed in control mice treated with PBS. The composite sclerosis score was 18% higher, dermal thickness was 19% higher, the number of alpha-SMA-positive cells was 47% higher, and the amount of hydroxyproline was 57% higher in TRPV1(-/-) mice than in their WT counterparts. Similarly, the composite sclerosis score was 47% higher, dermal thickness was 29% higher, the number of alpha-SMA-positive cells was 76% higher, and the amount of hydroxyproline was 30% higher in CGRP(-/-) mice than in the respective WT groups.

CONCLUSION

These results suggest that activation of the TRPV1 receptor by mediators of inflammation induces sensory neuropeptide release, which might exert protective action against fibrosis. We confirmed the protective role of CGRP in the development of cutaneous sclerosis.

A reactive oxygen species-mediated component in neurogenic vasodilatation

AIMS

Activation of the transient receptor potential vanilloid receptor 1 (TRPV1) leads to release of potent microvascular vasodilator neuropeptides. This study was designed to investigate in vivo mechanisms involved in TRPV1-mediated peripheral vasodilatation.

METHODS AND RESULTS

Wildtype (WT) and TRPV1 knockout (KO) mice were investigated in a model of peripheral vasodilatation. Blood flow was measured by laser Doppler flowmetry under anaesthesia and following local application of the TRPV1 agonist capsaicin. A sustained (60 min) increase in blood flow was observed in WT but not TRPV1 KO mouse ears. This response was resistant to blockers of classic vasodilators but inhibited in pharmacogenetic experiments that targeted blockade of the substance P (SP) and calcitonin gene-related peptide (CGRP) pathways. The TRPV1-mediated vasodilatation was also attenuated by treatment with superoxide dismutase and the hydrogen peroxide scavenger catalase, but not by deactivated enzymes, supporting a novel role for reactive oxygen species (ROS) generation. Furthermore, neurogenic vasodilatation was observed neither in the presence of the selective NADPH inhibitor apocynin, nor in gp91 phox KO mice, under conditions where prostaglandin E1-induced vasodilatation occurred. Finally, a role of neuropeptides in initiating a ROS-dependent component was verified as superoxide dismutase, catalase, and apocynin inhibited SP and CGRP vasodilatation.

CONCLUSION

These studies provide in vivo evidence that ROS are involved in mediating TRPV1- and neuropeptide-dependent neurogenic vasodilatation. An essential role of NADPH oxidase-dependent ROS is revealed that may be of fundamental importance to the neurogenic vasodilator component involved in circulatory homeostasis and the pathophysiology of certain cardiovascular diseases.

Targeted disruption of the galanin gene attenuates inflammatory responses in murine skin

The release of neuropeptides from primary sensory nerve fibers has been implicated in the modulation of local immune responses in surface tissues, such as the skin and the gastrointestinal mucosa, thereby inducing neurogenic inflammation, which is characterized by plasma extravasation and vasodilatation. In addition, cytokines, either alone or in conjunction with neuropeptides, initiate recruitment of immunocompetent cells such as neutrophils during the initial phases of inflammation. Growing evidence suggests that the neuropeptide galanin plays an important role in skin immune defense and pathophysiology. In this paper, we report that adult mice carrying a loss-of-function mutation in the galanin gene (galanin knockout, Gal KO) demonstrate an absence of the normal neurogenic inflammatory response, upon treatment of the skin either with the vanilloid receptor 1 agonist capsaicin or noxious heat. Furthermore, a lack of an acute inflammatory edema induced by coinjection of substance P and calcitonin gene-related peptide was observed. In addition, Gal KO animals also exhibit a deficit in neutrophil accumulation in the skin after exposure to noxious heat, carrageenin, or tumor necrosis factor alpha. These data indicate that Gal KO mice demonstrate abnormal neurogenic inflammatory responses in murine skin compared to strain-matched wild-type mice.

Nuclear and Cytoplasmic Expression of ErbB-4 in Prostate Cancer

Purpose

To evaluate cytoplasmic and nuclear ErbB-4 expression in prostate cancer specimens and its association with outcome.

Basic procedures

Specimens of 50 prostate cancer patients were investigated for ErbB-4 overexpression using immunohistochemistry staining. Cytoplasmic and nuclear staining was graded as 0–3 according to its intensity. The prognostic parameters were tumor stage, PSA level, Gleason score, probability of positive lymph nodes (Partin's tables and Roach equation), and 5-year disease free survival (Kattan nomogram).

Main findings

Overexpression of ErbB-4 (≥1) was detected in 30 (60%) patients and overexpression using cytoplasmic and nuclear staining was ≥2 in 19 (38%) and 17 (34%) patients, respectively. In only one third of the specimens was there any similarity between the 2 types of staining. Advanced tumor stage, high pretreatment PSA levels and high Gleason scores were evenly distributed among the patients with low (≤1) and intermediate/high (≥2) ErbB-4 expression. The probability of lymph node involvement and 5-year disease free survival were similar in both types of staining.

Principal conclusions

ErbB-4 was overexpressed (cytoplasmic and nuclear staining) in approximately one third of prostate cancer patients. The rate of similarity between the 2 staining types was only 33%: overexpression was evenly distributed among intermediate/high and low risk prostate cancer patients with both staining methods.

The transient receptor potential vanilloid 1 (TRPV1) receptor protects against the onset of sepsis after endotoxin

Transient potential vanilloid 1 (TRPV1) receptor is an ion channel receptor primarily localized on sensory nerves and activated by specific stimuli to initiate and amplify pain and inflammation, as typified by murine models of scald and arthritis. Little is known of the role of TRPV1 in sepsis, an infective disease associated with inflammation. Through use of a sublethal murine model of lipopolysaccharide-induced peritoneal sepsis, we provide novel evidence that genetic deletion of TRPV1 leads to an enhanced onset of various pathological components of systemic endotoxemia. Paired studies of TRPV1 knockout (KO) and wild-type mice demonstrate significantly enhanced hypotension (56+/-2% vs. 38+/-6% decrease in blood pressure, n=12), hypothermia (13+/-3% vs. 7+/-1% decrease in core temperature, n=6), and peritoneal exudate mediator levels (TNF-alpha, 0.78+/-0.2 vs. 0.38+/-0.1 ng/ml; nitrite, for NO, 35+/-10 vs. 15+/-3 microM; n=8) in TRPV1 KO mice, indicating loss of protective effect. Findings correlated with liver edema and raised plasma levels of aspartate aminotransferase in TRPV1 KO mice. These data suggest that TRPV1 may play an important regulatory role in sepsis independent of the major sensory neuropeptide substance P. The findings are relevant to developing strategies that increase the beneficial, and reduce the harmful, components of sepsis to prevent and treat this often fatal condition.

Defective ubiquitinylation of EGFR mutants of lung cancer confers prolonged signaling

Several distinct mutations within the kinase domain of the epidermal growth factor receptor (EGFR) are associated with non-small cell lung cancer, but mechanisms underlying their oncogenic potential are incompletely understood. Although normally ligand-induced kinase activation targets EGFR to Cbl-mediated receptor ubiquitinylation and subsequent degradation in lysosomes, we report that certain EGFR mutants escape this regulation. Defective endocytosis characterizes a deletion mutant of EGFR, as well as a point mutant (L858R-EGFR), whose association with c-Cbl and ubiquitinylation are impaired. Our data raise the possibility that refractoriness of L858R-EGFR to downregulation is due to enhanced heterodimerization with the oncogene product HER2, which leads to persistent stimulation.

How important are NK1 receptors for influencing microvascular inflammation and itch in the skin? Studies using Phoneutria nigriventer venom

Pain and itch sensations are induced by depolarization of C-fibre nerves and possibly other types of fibres. We have evidence from several species, including mice, that skin plasma extravasation induced by the Phoneutria nigriventer spider venom (PNV) is dependent on tachykinin NK(1) receptors. We have now investigated the itching measured as bouts of scratching in response to intradermal (i.d.) PNV in wildtype (NK(1)(+/+)) and NK(1) receptor knockout (NK(1)(-/-)) mice. Mice, either NK(1)(+/+) or NK(1)(-/-), were given a single i.d. injection (0.05 ml) of test agent or vehicle into the shaved dorsal skin, in the intercostal region, in a randomized way. The bouts of scratching were recorded in a blinded manner for 60 min. Oedema formation was concomitantly assessed by the extravascular accumulation of i.v. injected (125)I-albumin. The i.d. injection of either substance P (at a high dose of 100 nmol/site), or PNV (0.3-10 microg/site) induced oedema formation in NK(1)(+/+) but substantially less was observed in NK(1)(-/-) mice, as previously reported. PNV also induced scratching, but significantly less scratching was observed in NK(1)(-/-) compared with NK(1)(+/+) mice. In contrast, SP did not induce significant scratching at amounts up to 100 nmol in NK(1)(+/+) mice. Experiments with an NK(1) receptor antagonist SR140333 (at doses that blocked PNV-induced oedema) revealed that whilst a local co-injection i.d. (1 nmol) in NK(1)(+/+) mice had no effect on PNV (3 microg/site)-induced scratching (18.5+/-3.7 vs. 14.4+/-3.5 bouts, mean+/-S.E.M., n=5-7), systemic treatment with SR140333 (120 nmol/kg, i.v.) significantly inhibited scratching (14+/-3.5 vs. 3.1+/-1.2 bouts, n=4-6; P<0.05). These results indicate that NK(1) receptors are involved in mediating PNV-induced scratching and that the location of the receptors is unlikely to be skin. Thus, a distinct separation between endogenous microvascular and PNV nociceptive NK(1)-dependent effects is suggested.

Literacy and race predictors in localized prostate cancer treatment choice

14541

Background: Studies have shown that African American populations have low rates of surgery, while similar assessments based on literacy skills have not been reported. Methods: Newly diagnosed prostate cancer patients (n = 311) were approached at 3 hospitals: private, county, and VA. Patients completed demographic and quality of life questionnaires as well as a literacy assessment at baseline, 3 month, and 12 month intervals. Results: Majority (60%) of African American patients were at low functional literacy. In multinomial regression analysis controlling for patient age, clinical stage at presentation, comorbidity, and treatment site, both African American race (RRR 2.4, 95% CI 1.35–5.91) and low literacy (6th grade reading level or below) were significantly and independently associated with a greater likelihood to receive external beam radiation treatment only in relation to other treatment options (AOR 4.26, 95% CI 2.34–7.75). Conclusions: In our inner city population of prostate cancer patients, white patients with high literacy skills opted for radical prostatectomy and persons with low literacy and/or African American race opted for radiation therapy.

No significant financial relationships to disclose.

ErbB1–4 expression in prostate cancer patients and its correlation to patients’ ethnicity and outcome

14615

Background: ErbB family is involved in both cancer progression and treatment response in solid tumors. Few inconclusive studies reported on ErbB over-expression in prostate cancer. We investigated ErbB1–4 expression in prostate cancer patients and its correlation to patients ethnicity and outcome. Methods: ErbB expression was evaluated by immunohistochemistry of prostate cancer specimen using polyclonal antibody (Santa Cruz, CA). The staining was recorded as negative (0/+1), moderately positive (+2) and highly positive (+3). Kattan nomogram was used to predict 5-yr progression-free probability, assuming that all patients received external beam radiation therapy (a total dose of 78 Gy) and hormonal manipulation. Origin was counted in all 43 patients: Ashkenazic patients were defined as those who immigrated from East/West Europe or North America and Sephardic patients - from Middle East and North Africa. Results: ErbB1 (+2/+3) was over-expressed in 12 and 7 patients for a total of 19/43 (44%). ErbB2 over-expression (+2/+3) was not found in all patients. ErbB3 over-expression of +2 was seen in 2 patients and none had +3 (2/43, 5%). ErbB4 over-expression (+2/+3) was seen in 5 and 11 patients for a total of 16/43 (37%). 22 patients were Ashkenazic and 21 - Sephardic. ErbB1 over-expression in Ashkenazic and Sephardic groups was 9/22 (41%) and 10/21 (48%). ErbB4 over-expression in the two groups was 7/22 (32%) and 9/21 (43%). Kattan score of <80 was seen in 20/43 and <60 in 7/43 patients. ErbB1 over-expression was noted in 11/20 and in 4/7 patients. ErbB4 over-expression was seen in 7/20 and in 4/7 patients. In both ErbB1 and ErbB4 over-expression and Kattan nomogram of <80 and <60 the Sephardic ethnicity dominated-7/11 (64%), 3/4 (75%), 5/7 (71%) and 3/4 (75%). Conclusions: ErbB1 and ErbB4 over-expression is presented in 43% and 37% patients while ErbB3 was over-expressed in 5%; no over-expression of ErbB2 was observed. Ashkenazic and Sephardic ethnicity were evenly distributed in the over-expressed ErbB1 and ErbB4 patients. However, a tendency to a worse prognosis, based on Kattan nomogram, was seen in over-expressed ErbB1 and ErbB4 patients from Sephardic ethnicity. Further studies on ethnicity and ErbB prevalence and prognosis are warranted.

No significant financial relationships to disclose.

Curcumin synergistically potentiates the growth inhibitory and pro-apoptotic effects of celecoxib in pancreatic adenocarcinoma cells

BACKGROUND AND AIM

Adenocarcinoma of the Pancreas is a leading cause of cancer-related mortality, accounting for an estimated 30,000 deaths per year in the United States. Multiple studies have indicated that specific cyclooxygenase-2 (COX-2) inhibitors may serve in the prevention and treatment of a variety of malignancies including pancreatic adenocarcinoma. Recent studies had shown that the long-term use of high concentration of COX-2 inhibitors is not toxic free and may be limited due to serious gastrointestinal and cardiovascular side effects. The chemopreventive efficacy of the phytochemical, curcumin has been demonstrated in several in vitro and animal models. In this study we investigated whether curcumin potentiates the growth inhibition effect of a COX-2 inhibitor (celecoxib, Pfizer, NY, USA) in human pancreatic cancer cells.

METHODS

P-34 (expressing high levels of COX-2), and MIAPaCa (expressing low levels of COX-2) and Panc-1 (no expression of COX-2) evaluated cell lines were exposed to different concentrations of celecoxib (0-40 microM), curcumin (0-20 microM) and their combination. Cell viability was by XTT assay. Apoptosis was assessed by flow cytometry and COX-2 expression was measured by Western blotting analysis.

RESULTS

In P-34 cells, curcumin synergistically potentiated the inhibitory effect of celecoxib on cell growth. The growth inhibition was associated with inhibition of proliferation and induction of apoptosis. Western blot analysis showed that COX-2 expression was down-regulated by the combination therapy.

CONCLUSION

Curcumin synergistically augments the growth inhibition inserted by celecoxib in pancreatic cancer cells expressing COX-2. The synergistic effect was mediated through inhibition of COX-2. This may enable the use of celecoxib at lower and safer concentrations and may pave the way for a more effective treatment in this devastating disease.

OTOF mutations revealed by genetic analysis of hearing loss families including a potential temperature sensitive auditory neuropathy allele

INTRODUCTION

The majority of hearing loss in children can be accounted for by genetic causes. Non-syndromic hearing loss accounts for 80% of genetic hearing loss in children, with mutations in DFNB1/GJB2 being by far the most common cause. Among the second tier genetic causes of hearing loss in children are mutations in the DFNB9/OTOF gene.

METHODS

In total, 65 recessive non-syndromic hearing loss families were screened by genotyping for association with the DFNB9/OTOF gene. Families with genotypes consistent with linkage or uninformative for linkage to this gene region were further screened for mutations in the 48 known coding exons of otoferlin.

RESULTS

Eight OTOF pathological variants were discovered in six families. Of these, Q829X was found in two families. We also noted 23 other coding variant, believed to have no pathology. A previously published missense allele I515T was found in the heterozygous state in an individual who was observed to be temperature sensitive for the auditory neuropathy phenotype.

CONCLUSIONS

Mutations in OTOF cause both profound hearing loss and a type of hearing loss where otoacoustic emissions are spared called auditory neuropathy.

Involvement of transient receptor potential vanilloid 1 in the vascular and hyperalgesic components of joint inflammation

OBJECTIVE

To investigate the endogenous involvement of transient receptor potential vanilloid 1 (TRPV1) in a model of knee joint inflammation in the mouse.

METHODS

Following characterization of wild-type (WT) and TRPV1-knockout mice, inflammation was induced via intraarticular (IA) injection of Freund's complete adjuvant (CFA). Knee swelling was assessed as diameter, and inflammatory heat hyperalgesia was determined using the Hargreaves technique, for up to 3 weeks. At 18 hours, acute hyperpermeability was measured with 125I-albumin, and cytokines and myeloperoxidase activity, a marker of neutrophils, were assayed in synovial fluid extracts. The possibility that exogenous tumor necrosis factor alpha (TNFalpha) was involved in influencing TRPV1 activation was investigated in separate experiments.

RESULTS

Increased levels of knee swelling, hyperpermeability, leukocyte accumulation, and TNFalpha were found in WT mice 18 hours after IA CFA treatment compared with saline treatment. Significantly less knee swelling and hyperpermeability were found in TRPV1-/- mice, but leukocyte accumulation and TNFalpha levels were similar in WT and TRPV1-/- mice. Knee swelling in response to CFA remained significantly higher for a longer period in WT mice compared with TRPV1-/- mice, with thermal hyperalgesic sensitivity observed at 24 hours and at 1 week in WT, but not TRPV1-/-, mice. Knee swelling was attenuated (P < 0.05) in TRPV1-/- compared with WT mice 4 hours after IA administration of TNFalpha.

CONCLUSION

Our findings indicate that TRPV1 has a role in acute and chronic inflammation in the mouse knee joint. Thus, selective antagonism of TRPV1 should be considered as a potential target for treatment of acute and chronic joint inflammation.

Auditory brain-stem, middle- and long-latency evoked potentials in mild cognitive impairment

OBJECTIVE

Mild cognitive impairment (MCI) is a selective episodic memory deficit in the elderly with a high risk of Alzheimer's disease. The amplitudes of a long-latency auditory evoked potential (P50) are larger in MCI compared to age-matched controls. We tested whether increased P50 amplitudes in MCI were accompanied by changes of middle-latency potentials occurring around 50 ms and/or auditory brain-stem potentials.

METHODS

Auditory evoked potentials were recorded from age-matched controls (n = 16) and MCI (n = 17) in a passive listening paradigm at two stimulus presentation rates (2/s, 1/1.5 s). A subset of subjects also received stimuli at a rate of 1/3 s.

RESULTS

Relative to controls, MCI subjects had larger long-latency P50 amplitudes at all stimulus rates. Significant group differences in N100 amplitude were dependent on stimulus rate. Amplitudes of the middle-latency components (Pa, Nb, P1 peaking at approximately 30, 40, and 50 ms, respectively) did not differ between groups, but a slow wave between 30 and 49 ms on which the middle-latency components arose was significantly increased in MCI. ABR Wave V latency and amplitude did not differ significantly between groups.

CONCLUSIONS

The increase of long-latency P50 amplitudes in MCI reflects changes of a middle-latency slow wave, but not of transient middle-latency components. There was no evidence of group difference at the brain-stem level.

SIGNIFICANCE

Increased slow wave occurring as early as 50 ms may reflect neurophysiological consequences of neuropathology in MCI.

Time course of motor excitability before and after a task-related movement

AIMS OF THE STUDY

The time course of motor excitability during a task-related unilateral right thumb movement was studied using sub-threshold transcranial magnetic stimulation (TMS) to the contralateral left motor cortex. The level of stimulation evoked a motor evoked potential (MEP) in the thumb when the subject was at rest in approximately 10% of the trials.

METHODS

Subjects made a brief right thumb movement to the predictable omission of regularly presented tone bursts allowing experimental definition of TMS relative to the cue to move. Motor cortical excitability was characterized by amplitude and/or probability of eliciting MEPs.

RESULTS

There were four periods of altered motor excitability during task performance compared to a control resting state: a first period of weak facilitation before movement between -500 to -200 ms, a second period without increased excitability approximately 150 ms before movement onset when MEPs amplitude was below that seen in rest, a third period of strong facilitation between -100 ms before movement and +200 ms after facilitation and a fourth period of weak facilitation between +200 to +500 ms.

CONCLUSION

These results show that during performance of a task requiring a motor response, motor cortical excitability is increased above resting for hundreds of millisecond before and after the response, except for a transient period between 75 and 150 ms prior to movement onset. The temporal pattern of these excitability changes is compatible with multiple excitatory and inhibitory inputs interacting on motor cortex.