Subunit composition, molecular environment, and activation of native TRPC channels encoded by their interactomes

In the mammalian brain TRPC channels, a family of Ca²⁺-permeable cation channels, are involved in a variety of processes from neuronal growth and synapse formation to transmitter release, synaptic transmission and plasticity. The molecular appearance and operation of native TRPC channels, however, remained poorly understood. Here, we used high-resolution proteomics to show that TRPC channels in the rodent brain are macro-molecular complexes of more than 1 MDa in size that result from the co-assembly of the tetrameric channel core with an ensemble of interacting proteins (interactome). The core(s) of TRPC1-, C4-, and C5-containing channels are mostly heteromers with defined stoichiometries for each subtype, whereas TRPC3, C6, and C7 preferentially form homomers. In addition, TRPC1/C4/C5 channels may co-assemble with the metabotropic glutamate receptor mGluR1, thus guaranteeing both specificity and reliability of channel activation via the phospholipase-Ca²⁺ pathway. Our results unveil the subunit composition of native TRPC channels and resolve the molecular details underlying their activation.

Alix is required for activity-dependent bulk endocytosis at brain synapses

In chemical synapses undergoing high frequency stimulation, vesicle components can be retrieved from the plasma membrane via a clathrin-independent process called activity-dependent bulk endocytosis (ADBE). Alix (ALG-2-interacting protein X/PDCD6IP) is an adaptor protein binding to ESCRT and endophilin-A proteins which is required for clathrin-independent endocytosis in fibroblasts. Alix is expressed in neurons and concentrates at synapses during epileptic seizures. Here, we used cultured neurons to show that Alix is recruited to presynapses where it interacts with and concentrates endophilin-A during conditions triggering ADBE. Using Alix knockout (ko) neurons, we showed that this recruitment, which requires interaction with the calcium-binding protein ALG-2, is necessary for ADBE. We also found that presynaptic compartments of Alix ko hippocampi display subtle morphological defects compatible with flawed synaptic activity and plasticity detected electrophysiologically. Furthermore, mice lacking Alix in the forebrain undergo less seizures during kainate-induced status epilepticus and reduced propagation of the epileptiform activity. These results thus show that impairment of ADBE due to the lack of neuronal Alix leads to abnormal synaptic recovery during physiological or pathological repeated stimulations.

The adaptor protein Alix (PDCD6IP) is necessary for membrane shaping underlying various biological processes including endocytosis. This study shows that Alix mediates activity-dependent bulk endocytosis and is required for correct synaptic physiology under normal and pathological conditions.

A longer isoform of Stim1 is a negative SOCE regulator but increases cAMP-modulated NFAT signaling

Alternative splicing is a potent modifier of protein function. Stromal interaction molecule 1 (Stim1) is the essential activator of store‐operated Ca²⁺ entry (SOCE) triggering activation of transcription factors. Here, we characterize Stim1A, a splice variant with an additional 31 amino acid domain inserted in frame within its cytosolic domain. Prominent expression of exon A is found in astrocytes, heart, kidney, and testes. Full‐length Stim1A functions as a dominant‐negative regulator of SOCE and I_CRAC, facilitating sequence‐specific fast calcium‐dependent inactivation and destabilizing gating of Orai channels. Downregulation or absence of native Stim1A results in increased SOCE. Despite reducing SOCE, Stim1A leads to increased NFAT translocation. Differential proteomics revealed an interference of Stim1A with the cAMP‐SOCE crosstalk by altered modulation of phosphodiesterase 8 (PDE8), resulting in reduced cAMP degradation and increased PIP5K activity, facilitating NFAT activation. Our study uncovers a hitherto unknown mechanism regulating NFAT activation and indicates that cell‐type‐specific splicing of Stim1 is a potent means to regulate the NFAT signalosome and cAMP‐SOCE crosstalk.

A synaptic temperature sensor for body cooling

Deep brain temperature detection by hypothalamic warm-sensitive neurons (WSNs) has been proposed to provide feedback information relevant for thermoregulation. WSNs increase their action potential firing rates upon warming, a property that has been presumed to rely on the composition of thermosensitive ion channels within WSNs. Here, we describe a synaptic mechanism that regulates temperature sensitivity of preoptic WSNs and body temperature. Experimentally induced warming of the mouse hypothalamic preoptic area in vivo triggers body cooling. TRPM2 ion channels facilitate this homeostatic response and, at the cellular level, enhance temperature responses of WSNs, thereby linking WSN function with thermoregulation for the first time. Rather than acting within WSNs, we-unexpectedly-find TRPM2 to temperature-dependently increase synaptic drive onto WSNs by disinhibition. Our data emphasize a network-based interoceptive paradigm that likely plays a key role in encoding body temperature and that may facilitate integration of diverse inputs into thermoregulatory pathways.

Remodelling of Ca2+ homeostasis is linked to enlarged endoplasmic reticulum in secretory cells

The endoplasmic reticulum (ER) is extensively remodelled during the development of professional secretory cells to cope with high protein production. Since ER is the principal Ca²⁺ store in the cell, we characterised the Ca²⁺ homeostasis in NALM-6 and RPMI 8226 cells, which are commonly used as human pre-B and antibody secreting plasma cell models, respectively. Expression levels of Sec61 translocons and the corresponding Sec61-mediated Ca²⁺ leak from ER, Ca²⁺ storage capacity and store-operated Ca²⁺ entry were significantly enlarged in the secretory RPMI 8226 cell line. Using an immunoglobulin M heavy chain producing HeLa cell model, we found that the enlarged Ca²⁺ storage capacity and Ca²⁺ leak from ER are linked to ER expansion. Our data delineates a developmental remodelling of Ca²⁺ homeostasis in professional secretory cells in which a high Sec61-mediated Ca²⁺ leak and, thus, a high Ca²⁺ turnover in the ER is backed up by enhanced store-operated Ca²⁺ entry.

A short isoform of STIM1 confers frequency-dependent synaptic enhancement

Store-operated Ca2+-entry (SOCE) regulates basal and receptor-triggered Ca2+ signaling with STIM proteins sensing the endoplasmic reticulum (ER) Ca2+ content and triggering Ca2+ entry by gating Orai channels. Although crucial for immune cells, STIM1's role in neuronal Ca2+ homeostasis is controversial. Here, we characterize a splice variant, STIM1B, which shows exclusive neuronal expression and protein content surpassing conventional STIM1 in cerebellum and of significant abundance in other brain regions. STIM1B expression results in a truncated protein with slower kinetics of ER-plasma membrane (PM) cluster formation and ICRAC, as well as reduced inactivation. In primary wild-type neurons, STIM1B is targeted by its spliced-in domain B to presynaptic sites where it converts classic synaptic depression into Ca2+- and Orai-dependent short-term synaptic enhancement (STE) at high-frequency stimulation (HFS). In conjunction with altered STIM1 splicing in human Alzheimer disease, our findings highlight STIM1 splicing as an important regulator of neuronal calcium homeostasis and of synaptic plasticity.

Synergistic actions of v-SNARE transmembrane domains and membrane-curvature modifying lipids in neurotransmitter release

Vesicle fusion is mediated by assembly of SNARE proteins between opposing membranes. While previous work suggested an active role of SNARE transmembrane domains (TMDs) in promoting membrane merger (Dhara et al., 2016), the underlying mechanism remained elusive. Here, we show that naturally-occurring v-SNARE TMD variants differentially regulate fusion pore dynamics in mouse chromaffin cells, indicating TMD flexibility as a mechanistic determinant that facilitates transmitter release from differentially-sized vesicles. Membrane curvature-promoting phospholipids like lysophosphatidylcholine or oleic acid profoundly alter pore expansion and fully rescue the decelerated fusion kinetics of TMD-rigidifying VAMP2 mutants. Thus, v-SNARE TMDs and phospholipids cooperate in supporting membrane curvature at the fusion pore neck. Oppositely, slowing of pore kinetics by the SNARE-regulator complexin-2 withstands the curvature-driven speeding of fusion, indicating that pore evolution is tightly coupled to progressive SNARE complex formation. Collectively, TMD-mediated support of membrane curvature and SNARE force-generated membrane bending promote fusion pore formation and expansion.

TRPC channels regulate Ca2+-signaling and short-term plasticity of fast glutamatergic synapses

Transient receptor potential (TRP) proteins form Ca²⁺-permeable, nonselective cation channels, but their role in neuronal Ca²⁺ homeostasis is elusive. In the present paper, we show that TRPC channels potently regulate synaptic plasticity by changing the presynaptic Ca²⁺-homeostasis of hippocampal neurons. Specifically, loss of TRPC1/C4/C5 channels decreases basal-evoked secretion, reduces the pool size of readily releasable vesicles, and accelerates synaptic depression during high-frequency stimulation (HFS). In contrast, primary TRPC5 channel-expressing neurons, identified by a novel TRPC5–τ-green fluorescent protein (τGFP) knockin mouse line, show strong short-term enhancement (STE) of synaptic signaling during HFS, indicating a key role of TRPC5 in short-term plasticity. Lentiviral expression of either TRPC1 or TRPC5 turns classic synaptic depression of wild-type neurons into STE, demonstrating that TRPCs are instrumental in regulating synaptic plasticity. Presynaptic Ca²⁺ imaging shows that TRPC activity strongly boosts synaptic Ca²⁺ dynamics, showing that TRPC channels provide an additional presynaptic Ca²⁺ entry pathway, which efficiently regulates synaptic strength and plasticity.

Transient receptor potential (TRP) proteins can form non-selective cation channels, but their role in synaptic transmission is poorly understood. This study shows that calcium-permeable TRPC channels provide an additional calcium entry pathway at presynaptic sites and are efficient regulators of synaptic strength and plasticity.

A mechanism for exocytotic arrest by the Complexin C-terminus

ComplexinII (CpxII) inhibits non-synchronized vesicle fusion, but the underlying mechanisms have remained unclear. Here, we provide evidence that the far C-terminal domain (CTD) of CpxII interferes with SNARE assembly, thereby arresting tonic exocytosis. Acute infusion of a CTD-derived peptide into mouse chromaffin cells enhances synchronous release by diminishing premature vesicle fusion like full-length CpxII, indicating a direct, inhibitory function of the CTD that sets the magnitude of the primed vesicle pool. We describe a high degree of structural similarity between the CpxII CTD and the SNAP25-SN1 domain (C-terminal half) and show that the CTD peptide lowers the rate of SDS-resistant SNARE complex formation in vitro. Moreover, corresponding CpxII:SNAP25 chimeras do restore complexin's function and even 'superclamp' tonic secretion. Collectively, these results support a so far unrecognized clamping mechanism wherein the CpxII C-terminus hinders spontaneous SNARE complex assembly, enabling the build-up of a release-ready pool of vesicles for synchronized Ca²⁺-triggered exocytosis.

Circulating bile acids in healthy adults respond differently to a dietary pattern characterized by whole grains, legumes and fruits and vegetables compared to a diet high in refined grains and added sugars: A randomized, controlled, crossover feeding study

OBJECTIVE

The effects of diets high in refined grains on biliary and colonic bile acids have been investigated extensively. However, the effects of diets high in whole versus refined grains on circulating bile acids, which can influence glucose homeostasis and inflammation through activation of farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (TGR5), have not been studied.

MATERIALS AND METHODS

We conducted a secondary analysis from a randomized controlled crossover feeding trial (NCT00622661) in 80 healthy adults (40 women/40 men, age 18-45 years) from the greater Seattle Area, half of which were normal weight (BMI 18.5-25.0 kg/m²) and half overweight to obese (BMI 28.0-39.9 kg/m²). Participants consumed two four-week controlled diets in randomized order: 1) a whole grain diet (WG diet), designed to be low in glycemic load (GL), high in whole grains, legumes, and fruits and vegetables, and 2) a refined grain diet (RG diet), designed to be high GL, high in refined grains and added sugars, separated by a four-week washout period. Quantitative targeted analysis of 55 bile acid species in fasting plasma was performed using liquid chromatography tandem mass spectrometry. Concentrations of glucose, insulin, and CRP were measured in fasting serum. Linear mixed models were used to test the effects of diet on bile acid concentrations, and determine the association between plasma bile acid concentrations and HOMA-IR and CRP. Benjamini-Hochberg false discovery rate (FDR) < 0.05 was used to control for multiple testing.

RESULTS

A total of 29 plasma bile acids were reliably detected and retained for analysis. Taurolithocholic acid (TLCA), taurocholic acid (TCA) and glycocholic acid (GCA) were statistically significantly higher after the WG compared to the RG diet (FDR < 0.05). There were no significant differences by BMI or sex. When evaluating the association of bile acids and HOMA-IR, GCA, taurochenodeoxycholic acid, ursodeoxycholic acid (UDCA), 5β‑cholanic acid‑3β,12α‑diol, 5‑cholanic acid‑3β‑ol, and glycodeoxycholic acid (GDCA) were statistically significantly positively associated with HOMA-IR individually, and as a group, total, 12α‑hydroxylated, primary and secondary bile acids were also significant (FDR < 0.05). When stratifying by BMI, chenodeoxycholic acid (CDCA), cholic acid (CA), UDCA, 5β-cholanic acid-3β, deoxycholic acid, and total, 12α-hydroxylated, primary and secondary bile acid groups were significantly positively associated with HOMA-IR among overweight to obese individuals (FDR < 0.05). When stratifying by sex, GCA, CDCA, TCA, CA, UDCA, GDCA, glycolithocholic acid (GLCA), total, primary, 12α‑hydroxylated, and glycine-conjugated bile acids were significantly associated with HOMA-IR among women, and CDCA, GDCA, and GLCA were significantly associated among men (FDR < 0.05). There were no significant associations between bile acids and CRP.

CONCLUSIONS

Diets with comparable macronutrient and energy composition, but differing in carbohydrate source, affected fasting plasma bile acids differently. Specifically, a diet characterized by whole grains, legumes, and fruits and vegetables compared to a diet high in refined grains and added sugars led to modest increases in concentrations of TLCA, TCA and GCA, ligands for FXR and TGR5, which may have beneficial effects on glucose homeostasis.

Astrocytes control synaptic strength by two distinct v-SNARE-dependent release pathways

Communication between glia cells and neurons is crucial for brain functions, but the molecular mechanisms and functional consequences of gliotransmission remain enigmatic. Here we report that astrocytes express synaptobrevin II and cellubrevin as functionally non-overlapping vesicular SNARE proteins on glutamatergic vesicles and neuropeptide Y-containing large dense-core vesicles, respectively. Using individual null-mutants for Vamp2 (synaptobrevin II) and Vamp3 (cellubrevin), as well as the corresponding compound null-mutant for genes encoding both v-SNARE proteins, we delineate previously unrecognized individual v-SNARE dependencies of astrocytic release processes and their functional impact on neuronal signaling. Specifically, we show that astroglial cellubrevin-dependent neuropeptide Y secretion diminishes synaptic signaling, while synaptobrevin II-dependent glutamate release from astrocytes enhances synaptic signaling. Our experiments thereby uncover the molecular mechanisms of two distinct v-SNARE-dependent astrocytic release pathways that oppositely control synaptic strength at presynaptic sites, elucidating new avenues of communication between astrocytes and neurons.

Plasma metabolite abundances are associated with urinary enterolactone excretion in healthy participants on controlled diets

Enterolignans, products of gut bacterial metabolism of plant lignans, have been associated with reduced risk of chronic diseases, but their association with other plasma metabolites is unknown. We examined plasma metabolite profiles according to urinary enterolignan excretion in a cross-sectional analysis using data from a randomized crossover, controlled feeding study. Eighty healthy adult males and females completed two 28-day feeding periods differing by glycemic load, refined carbohydrate, and fiber content. Lignan intake was calculated from food records using a polyphenol database. Targeted metabolomics was performed by LC-MS on plasma from fasting blood samples collected at the end of each feeding period. Enterolactone (ENL) and enterodiol, were measured in 24 h urine samples collected on the penultimate day of each study period using GC-MS. Linear mixed models were used to test the association between enterolignan excretion and metabolite abundances. Pathway analyses were conducted using the Global Test. Benjamini-Hochberg false discovery rate (FDR) was used to control for multiple testing. Of the metabolites assayed, 121 were detected in all samples. ENL excretion was associated positively with plasma hippuric acid and melatonin, and inversely with epinephrine, creatine, glycochenodeoxycholate, and glyceraldehyde (P < 0.05). Hippuric acid only satisfied the FDR of q < 0.1. END excretion was associated with myristic acid and glycine (q < 0.5). Two of 57 pathways tested were associated significantly with ENL, ubiquinone and terpenoid-quinone biosynthesis, and inositol phosphate metabolism. These results suggest a potential role for ENL or ENL-metabolizing gut bacteria in regulating plasma metabolites.

Heteromeric channels formed by TRPC1, TRPC4 and TRPC5 define hippocampal synaptic transmission and working memory

Canonical transient receptor potential (TRPC) channels influence various neuronal functions. Using quantitative high-resolution mass spectrometry, we demonstrate that TRPC1, TRPC4, and TRPC5 assemble into heteromultimers with each other, but not with other TRP family members in the mouse brain and hippocampus. In hippocampal neurons from Trpc1/Trpc4/Trpc5-triple-knockout (Trpc1/4/5^-/-) mice, lacking any TRPC1-, TRPC4-, or TRPC5-containing channels, action potential-triggered excitatory postsynaptic currents (EPSCs) were significantly reduced, whereas frequency, amplitude, and kinetics of quantal miniature EPSC signaling remained unchanged. Likewise, evoked postsynaptic responses in hippocampal slice recordings and transient potentiation after tetanic stimulation were decreased. In vivo, Trpc1/4/5^-/- mice displayed impaired cross-frequency coupling in hippocampal networks and deficits in spatial working memory, while spatial reference memory was unaltered. Trpc1/4/5^-/- animals also exhibited deficiencies in adapting to a new challenge in a relearning task. Our results indicate the contribution of heteromultimeric channels from TRPC1, TRPC4, and TRPC5 subunits to the regulation of mechanisms underlying spatial working memory and flexible relearning by facilitating proper synaptic transmission in hippocampal neurons.

Investigation of a Lifestyle Intervention in Women at High Risk of Breast Cancer

One fourth of breast cancer can be attributed to sedentary lifestyles and being overweight or obese. This pilot study was conducted to explore whether a 6-month lifestyle intervention affected body composition and obesity-related biomarkers among women at high risk of breast cancer. Overweight/obese women at high risk of breast cancer were randomized to the control group or to the intervention. The intervention was an individually tailored, cognitive-behavioral therapy program that assists women in identifying strategies to improve their nutrition and physical activity habits with the goal of reduced adiposity. We compared changes in body composition and plasma biomarkers from baseline to 6 months. Body weight, adiposity, leptin, insulin resistance, and C-reactive protein were significantly reduced in the intervention group versus controls. No significant differences were observed in adiponectin, insulin, glucose, or interleukin-6. Our findings suggest that this intervention improves the metabolic and inflammatory profiles of overweight/obese women at risk of breast cancer.

Dietary biomarker evaluation in a controlled feeding study in women from the Women's Health Initiative cohort

BACKGROUND

Controlled human feeding studies are necessary for robust nutritional biomarker development and validation. Previous feeding studies have typically evaluated single nutrients and tested relatively few diets.

OBJECTIVES

The objectives were 1) to simultaneously associate dietary intake with a range of potential nutritional biomarkers in postmenopausal women by using a controlled feeding study whereby each participant was provided a diet similar to her usual diet and 2) to evaluate serum concentrations of select nutrients as potential biomarkers with the use of established urinary recovery biomarkers of energy and protein as benchmarks for evaluation.

DESIGN

Postmenopausal women from the Women's Health Initiative (n = 153) were provided with a 2-wk controlled diet in which each individual's menu approximated her habitual food intake as estimated from her 4-d food record and adjusted for estimated energy requirements. Serum biomarkers, including carotenoids, tocopherols, folate, vitamin B-12, and phospholipid fatty acids, were collected at the beginning and end of the feeding period. Doubly labeled water and urinary nitrogen biomarkers were used to derive estimates of energy and protein consumption, respectively.

RESULTS

Linear regression of (ln-transformed) consumed nutrients on (ln-transformed) potential biomarkers and participant characteristics led to the following regression (R²) values for serum concentration biomarkers: folate, 0.49; vitamin B-12, 0.51; α-carotene, 0.53; β-carotene, 0.39; lutein + zeaxanthin, 0.46; lycopene, 0.32; and α-tocopherol, 0.47. R² values for percentage of energy from polyunsaturated fatty acids and urinary recovery biomarkers of energy and protein intakes were 0.27, 0.53, and 0.43, respectively. Phospholipid saturated fatty acids and monounsaturated fatty acids and serum γ-tocopherol were weakly associated with intake (R² < 0.25).

CONCLUSIONS

Serum concentration biomarkers of several vitamins and carotenoids performed similarly to established energy and protein urinary recovery biomarkers in representing nutrient intake variation in a feeding study, and thus are likely suitable for application in this population of postmenopausal women. Further work is needed to identify objective measures of categories of fatty acid intake. This trial was registered at clinicaltrials.gov as NCT00000611.

Large dense-core vesicle exocytosis from mouse dorsal root ganglion neurons is regulated by neuropeptide Y

Peptidergic dorsal root ganglion (DRG) neurons transmit sensory and nociceptive information from the periphery to the central nervous system. Their synaptic activity is profoundly affected by neuromodulatory peptides stored and released from large dense-core vesicles (LDCVs). However, the mechanism of peptide secretion from DRG neurons is poorly understood. Using total internal reflection fluorescence microscopy (TIRFM), we visualized individual LDCVs loaded with fluorescent neuropeptide Y (NPY) and analyzed their stimulation-dependent release. We tested several protocols and found an overall low stimulation-secretion coupling that increased after raising intracellular Ca²⁺ concentration by applying a weak pre-stimulus. Interestingly, the stimulation protocol also influenced the mechanism of LDCV fusion. Depolarization of DRG neurons with a solution containing 60mM KCl triggered full fusion, kiss-and-run, and kiss-and-stay exocytosis with equal frequency. In contrast, field electrode stimulation primarily induced full fusion exocytosis. Finally, our results indicate that NPY can promote LDCV secretion. These results shed new light on the mechanism of NPY action during modulation of DRG neuron activity, an important pathway in the treatment of chronic pain.

v-SNARE transmembrane domains function as catalysts for vesicle fusion

Vesicle fusion is mediated by an assembly of SNARE proteins between opposing membranes, but it is unknown whether transmembrane domains (TMDs) of SNARE proteins serve mechanistic functions that go beyond passive anchoring of the force-generating SNAREpin to the fusing membranes. Here, we show that conformational flexibility of synaptobrevin-2 TMD is essential for efficient Ca(2+)-triggered exocytosis and actively promotes membrane fusion as well as fusion pore expansion. Specifically, the introduction of helix-stabilizing leucine residues within the TMD region spanning the vesicle's outer leaflet strongly impairs exocytosis and decelerates fusion pore dilation. In contrast, increasing the number of helix-destabilizing, ß-branched valine or isoleucine residues within the TMD restores normal secretion but accelerates fusion pore expansion beyond the rate found for the wildtype protein. These observations provide evidence that the synaptobrevin-2 TMD catalyzes the fusion process by its structural flexibility, actively setting the pace of fusion pore expansion.

Targeted plasma metabolome response to variations in dietary glycemic load in a randomized, controlled, crossover feeding trial in healthy adults

Low versus high glycemic load (GL) diet patterns are inversely associated with obesity and chronic diseases such as cancer and cardiovascular disease. These associations persist beyond the protection afforded by increased fiber alone, representing an important gap in our understanding of the metabolic effects of GL. We conducted a randomized, controlled, crossover feeding trial of two 28-day diet periods of high and low GL. Using LC-MS, targeted metabolomics analysis of 155 metabolites was performed on plasma samples from 19 healthy adults aged 18-45 years. Fourteen metabolites differed significantly between diets (P < 0.05), with kynurenate remaining significant after Bonferroni correction (P < 4 × 10(-4)). Metabolites with the largest difference in abundance were kynurenate and trimethylamine-N-oxide (TMAO), both significantly higher after consumption of the low GL diet. Partial least squares-discriminant analysis showed clear separation between the two diets; however no specific pathway was identified in pathway analyses. We found significant differences in 14 plasma metabolites suggesting a differing metabolic response to low and high GL diets. Kynurenate is associated with reduced inflammation, and may be one mechanism through which protective effects of a low GL diet are manifested and warrants further evaluation. This trial was registered at clinicaltrials.gov as NCT00622661.

Cruciferous vegetables have variable effects on biomarkers of systemic inflammation in a randomized controlled trial in healthy young adults

BACKGROUND

Isothiocyanates in cruciferous vegetables modulate signaling pathways critical to carcinogenesis, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a central regulator of inflammation. Glutathione S-transferase (GST) M1 and GSTT1 metabolize isothiocyanates; genetic variants may result in differences in biologic response.

OBJECTIVE

The objective of this study was to test whether consumption of cruciferous or cruciferous plus apiaceous vegetables altered serum concentrations of interleukin (IL)-6, IL-8, C-reactive protein (CRP), tumor necrosis factor (TNF) α, and soluble TNF receptor (sTNFR) I and II, and whether this response was GSTM1/GSTT1 genotype dependent.

METHODS

In a randomized crossover trial, healthy men (n = 32) and women (n = 31) aged 20-40 y consumed 4 14-d controlled diets: basal (vegetable-free), single-dose cruciferous (1xC) [7 g vegetables/kg body weight (BW)], double-dose cruciferous (2xC) (14 g/kg BW), and cruciferous plus apiaceous (carrot family) (1xC+A) vegetables (7 and 4 g/kg BW, respectively), with a 21-d washout period between each intervention. Urinary isothiocyanate excretion was also evaluated as a marker of systemic isothiocyanate exposure. Fasting morning blood and urine samples were collected on days 0 and 14 and analyzed.

RESULTS

IL-6 concentrations were significantly lower on day 14 of the 2xC and 1xC+A diets than with the basal diet [-19% (95% CI: -30%, -0.1%) and -20% (95% CI: -31%, -0.7%), respectively]. IL-8 concentrations were higher after the 1xC+A diet (+16%; 95% CI: 4.2%, 35.2%) than after the basal diet. There were no effects of diet on CRP, TNF-α, or sTNFRI or II. There were significant differences between GSTM1-null/GSTT1+ individuals for several biomarkers in response to 1xC+A compared with basal diets (CRP: -37.8%; 95% CI: -58.0%, -7.4%; IL-6: -48.6%; 95% CI: -49.6%, -12.0%; IL-8: 16.3%; 95% CI: 6.7%, 57.7%) and with the 2xC diet compared with the basal diet (IL-8: -33.2%; 95% CI: -43.0%, -1.4%; sTNFRI: -7.5%; 95% CI: -12.7%, -2.3%). There were no significant reductions in biomarker concentrations in response to diet among GSTM1+/GSTT1+ or GSTM1-null/GSTT1-null individuals. Twenty-four-hour urinary isothiocyanate excretion was not associated with any of the inflammation markers overall; however, IL-6 was inversely associated with total isothiocyanate excretion in GSTM1-null/GSTT1-null individuals (β = -0.12; 95% CI: -0.19, -0.05).

CONCLUSIONS

In this young, healthy population, consumption of cruciferous and apiaceous vegetables reduced circulating IL-6; however, results for other biomarkers of inflammation were not consistent.

Complexin synchronizes primed vesicle exocytosis and regulates fusion pore dynamics

ComplexinII and SynaptotagminI coordinately transform the constitutively active SNARE-mediated fusion mechanism into a highly synchronized, Ca²⁺-triggered release apparatus.

ComplexinII (CpxII) and SynaptotagminI (SytI) have been implicated in regulating the function of SNARE proteins in exocytosis, but their precise mode of action and potential interplay have remained unknown. In this paper, we show that CpxII increases Ca²⁺-triggered vesicle exocytosis and accelerates its secretory rates, providing two independent, but synergistic, functions to enhance synchronous secretion. Specifically, we demonstrate that the C-terminal domain of CpxII increases the pool of primed vesicles by hindering premature exocytosis at submicromolar Ca²⁺ concentrations, whereas the N-terminal domain shortens the secretory delay and accelerates the kinetics of Ca²⁺-triggered exocytosis by increasing the Ca²⁺ affinity of synchronous secretion. With its C terminus, CpxII attenuates fluctuations of the early fusion pore and slows its expansion but is functionally antagonized by SytI, enabling rapid transmitter discharge from single vesicles. Thus, our results illustrate how key features of CpxII, SytI, and their interplay transform the constitutively active SNARE-mediated fusion mechanism into a highly synchronized, Ca²⁺-triggered release apparatus.

Metabolomic profiling of urine: response to a randomised, controlled feeding study of select fruits and vegetables, and application to an observational study

Metabolomic profiles were used to characterise the effects of consuming a high-phytochemical diet compared with a diet devoid of fruits and vegetables (F&V) in a randomised trial and cross-sectional study. In the trial, 8 h fasting urine from healthy men (n 5) and women (n 5) was collected after a 2-week randomised, controlled trial of two diet periods: a diet rich in cruciferous vegetables, citrus and soya (F&V), and a fruit- and vegetable-free (basal) diet. Among the ions found to differentiate the diets, 176 were putatively annotated with compound identifications, with forty-six supported by MS/MS fragment evidence. Metabolites more abundant in the F&V diet included markers of the dietary intervention (e.g. crucifers, citrus and soya), fatty acids and niacin metabolites. Ions more abundant in the basal diet included riboflavin, several acylcarnitines and amino acid metabolites. In the cross-sectional study, we compared the participants based on the tertiles of crucifers, citrus and soya from 3 d food records (n 36) and FFQ (n 57); intake was separately divided into the tertiles of total fruit and vegetable intake for FFQ. As a group, ions individually differential between the experimental diets differentiated the observational study participants. However, only four ions were significant individually, differentiating the third v. first tertile of crucifer, citrus and soya intake based on 3 d food records. One of these ions was putatively annotated: proline betaine, a marker of citrus consumption. There were no ions significantly distinguishing tertiles by FFQ. The metabolomic assessment of controlled dietary interventions provides a more accurate and stronger characterisation of the diet than observational data.

Effect of low- and high-glycemic load on circulating incretins in a randomized clinical trial

OBJECTIVE

Low-glycemic load diets lower post-prandial glucose and insulin responses; however, the effect of glycemic load on circulating incretin concentrations is unclear. We aimed to assess effects of dietary glycemic load on fasting and post-prandial glucose, insulin and incretin (i.e., glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1)) concentrations and to examine for effect modification by adiposity.

MATERIALS AND METHODS

We conducted a single-center, randomized controlled crossover feeding trial in which a subset of participants had post-prandial testing. Participants were recruited from the local Seattle area. We enrolled 89 overweight-obese (BMI 28.0-39.9 kg/m(2)) and lean (BMI 18.5-25.0 kg/m(2)) healthy adults. Participants consumed two 28-day, weight-maintaining high- and low-glycemic load controlled diets in random order. Primary outcome measures were post-prandial circulating concentrations of glucose, insulin, GIP and GLP-1, following a test breakfast.

RESULTS

Of the 80 participants completing both diet interventions, 16 had incretin testing and comprise the group for analyses. Following each 28-day high- and low-glycemic load diet, mean fasting concentrations of insulin, glucose, GIP and GLP-1 were not significantly different. Mean integrated post-prandial concentrations of glucose, insulin and GIP were higher (1504±476 mg/dL/min, p<0.01; 2012±644 μU/mL/min, p<0.01 and 15517±4062 pg/mL/min, p<0.01, respectively) and GLP-1 was lower (-81.6±38.5 pmol/L/min, p<0.03) following the high-glycemic load breakfast as compared to the low-glycemic load breakfast. Body fat did not significantly modify the effect of glycemic load on metabolic outcomes.

CONCLUSIONS

High-glycemic load diets in weight-maintained healthy individuals lead to higher post-prandial GIP and lower post-prandial GLP-1 concentrations. Future studies evaluating dietary glycemic load manipulation of incretin effects would be helpful for establishing diabetes nutrition guidelines.

Glycemic load effect on fasting and post-prandial serum glucose, insulin, IGF-1 and IGFBP-3 in a randomized, controlled feeding study

BACKGROUND/OBJECTIVES

The effect of a low glycemic load (GL) diet on insulin-like growth factor-1 (IGF-1) concentration is still unknown but may contribute to lower chronic disease risk. We aimed to assess the impact of GL on concentrations of IGF-1 and IGF-binding protein-3 (IGFBP-3).

SUBJECTS/METHODS

We conducted a randomized, controlled crossover feeding trial in 84 overweight obese and normal weight healthy individuals using two 28-day weight-maintaining high- and low-GL diets. Measures were fasting and post-prandial concentrations of insulin, glucose, IGF-1 and IGFBP-3. In all 80 participants completed the study and 20 participants completed post-prandial testing by consuming a test breakfast at the end of each feeding period. We used paired t-tests for diet component and linear mixed models for biomarker analyses.

RESULTS

The 28-day low-GL diet led to 4% lower fasting concentrations of IGF-1 (10.6 ng/ml, P=0.04) and a 4% lower ratio of IGF-1/IGFBP-3 (0.24, P=0.01) compared with the high-GL diet. The low-GL test breakfast led to 43% and 27% lower mean post-prandial glucose and insulin responses, respectively; mean incremental areas under the curve for glucose and insulin, respectively, were 64.3±21.8 (mmol/l/240 min; P<0.01) and 2253±539 (μU/ml/240 min; P<0.01) lower following the low- compared with the high-GL test meal. There was no effect of GL on mean homeostasis model assessment for insulin resistance or on mean integrated post-prandial concentrations of glucose-adjusted insulin, IGF-1 or IGFBP-3. We did not observe modification of the dietary effect by adiposity.

CONCLUSIONS

Low-GL diets resulted in 43% and 27% lower post-prandial responses of glucose and insulin, respectively, and modestly lower fasting IGF-1 concentrations. Further intervention studies are needed to weigh the impact of dietary GL on risk for chronic disease.

Reliability of serum biomarkers of inflammation from repeated measures in healthy individuals

BACKGROUND

Biomarkers of low-grade systemic inflammation are used to study the associations of inflammation with chronic diseases, including cancer. However, relatively little is known about the intraindividual variability of most of these measures.

METHODS

Fasting serum samples, collected at baseline and the end of ≥3-week washout periods in a four-diet crossover feeding trial, were used to measure the inflammatory markers high sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-8, and soluble TNF receptor (sTNFR) I and II. Participants included 62 men and women for analyses of IL-6 and CRP and 56 for analyses of IL-8, TNF-α, and sTNFRs, aged 20 to 40, who were free of factors known to influence inflammation, for example, chronic disease, medication use, heavy alcohol use, smoking, and obesity (body mass index >30 kg/m(2)). Intraclass correlations (ICC) were estimated using random effects ANOVA, across all four time points (~6 weeks apart).

RESULTS

ICCs for TNF-α and sTNFR I and II were very high: ICC = 0.92 [95% confidence interval (CI), 0.89-0.96], 0.92 (95% CI, 0.88-0.95), and 0.90 (95% CI, 0.85-0.94), respectively. ICCs for IL-8 and hsCRP were 0.73 (95% CI, 0.63-0.83) and 0.62 (95% CI, 0.49-0.75), respectively. The ICC for IL-6 was considerably lower, ICC = 0.48 (95% CI, 0.36-0.62). Three measures of IL-6 would be needed to achieve a reliability coefficient (Cronbach α) of 0.75.

CONCLUSIONS

With the exception of IL-6, reliability of all inflammatory markers in our panel was high.

IMPACT

This suggests that a single measure accurately captures the short-term (e.g., 4-6 months) variability within an individual.

Low glycemic load experimental diet more satiating than high glycemic load diet

Effective strategies for reducing food intake are needed to reduce risk of obesity-related cancers. We investigated the effect of low and high glycemic load (GL) diets on satiety and whether satiety varied by body mass index (BMI), gender, and serum leptin. Eighty normal weight (BMI = 18.5-24.9 kg/m²) and overweight/ obese (BMI = 28.0-40.0 kg/m²) adults participated in a randomized, crossover controlled feeding study testing low GL vs. high GL diets. The 28-day diets were isocaloric with identical macronutrient distributions, differing only in GL and fiber. Participants completed visual analog satiety surveys and fasting serum leptin after each 28-day period. T-tests compared mean within- and between-person satiety scores and leptin values. Participants reported 7% greater satiation on the low GL vs. the high GL diet (P = 0.03) and fewer food cravings on the low GL vs. the high GL diet (P < 0.001). Compared to males, females reported less hunger (P = 0.05) and more satiety on the low GL vs. the high GL diet (P < 0.01). Participants with low body fat (<25.0% for men; <32.0% for women) and BMI <25.0 kg/m² reported study food was tastier on the low GL vs. the high GL diet (P = 0.04 and P = 0.05, respectively). In summary, reducing GL, and/or increasing fiber, may be an effective way to lower calories consumed, improve energy balance, and ultimately reduce cancer risk.

Recruiting underrepresented groups into the Carbohydrates and Related Biomarkers (CARB) cancer prevention feeding study

Using data from a randomized, controlled feeding study, which aimed to recruit 88 participants (including 22 Hispanics and 22 African Americans), we examined strategies for recruiting individuals from underrepresented groups into research trials. Study eligibility criteria included participants who 1) were 18-45 years old; 2) had a body mass index (BMI) >18<24.9 or BMI>28.0 <40.0; 3); had no preexisting health conditions; 4) were non-smoking; 5) had normal fasting blood glucose level (<100 mg/dL); and 6) spoke English. Participants were recruited using two overarching methods: media-based strategies (flyers and posters, email announcements, announcements in local and campus newspapers, and the Internet) and in-person strategies (presentations in university classes and community events). Participants were enrolled March 2006-March 2009. We present the numbers of individuals requesting study information, completing pre-enrollment screening questionnaires, and enrolling in the study. A total of 1036 individuals requested study information, and 396 completed a pre-enrollment screening questionnaire; 90 enrolled in the study (22 Hispanics and 18 African Americans). Among enrolled participants, in-person recruitment strategies were reported by 39% of African Americans, 73% of Hispanics, and 30% of non-Hispanic Whites (P<0.001). In-person recruitment strategies were successful among Hispanics. Mass media recruitment strategies were successful among non-Hispanic Whites but enlisted relatively few Hispanic participants. Both strategies recruited nearly equal percentages of African Americans. These data suggest that different strategies are needed to effectively recruit racial/ethnic population subgroups into intervention studies.

A low-glycemic load diet reduces serum C-reactive protein and modestly increases adiponectin in overweight and obese adults

Low-glycemic load (GL) diets improve insulin resistance and glucose homeostasis in individuals with diabetes. Less is known about whether low-GL diets, independent of weight loss, improve the health profile for persons without diabetes or other preexisting conditions. We conducted a randomized, cross-over feeding study testing low- compared to High-GL diets on biomarkers of inflammation and adiposity in healthy adults. Eighty participants (n = 40 with BMI 18.5-24.9 kg/m²; n = 40 with BMI 28.0-40.0 kg/m²) completed two 28-d feeding periods in random order where one period was a high-GL diet (mean GL/d = 250) and the other a low-GL diet (mean GL/d = 125). Diets were isocaloric with identical macronutrient content (as percent energy). All food was provided and participants maintained weight and usual physical activity. Height, weight, and DXA were measured at study entry and weight assessed again thrice per week. Blood was drawn from fasting participants at the beginning and end of each feeding period and serum concentrations of high-sensitivity CRP, serum amyloid A, IL-6, leptin, and adiponectin were measured. Linear mixed models tested the intervention effect on the biomarkers; models were adjusted for baseline biomarker concentrations, diet sequence, feeding period, age, sex, and body fat mass. Among participants with high-body fat mass (>32.0% for males and >25.0% for females), the low-GL diet reduced CRP (P = 0.02) and marginally increased adiponectin (P = 0.06). In conclusion, carbohydrate quality, independent of energy, is important. Dietary patterns emphasizing low-GL foods may improve the inflammatory and adipokine profiles of overweight and obese individuals.

UGT1A6 and UGT2B15 polymorphisms and acetaminophen conjugation in response to a randomized, controlled diet of select fruits and vegetables

Acetaminophen (APAP) glucuronidation is thought to occur mainly by UDP-glucuronosyltransferases (UGT) in the UGT1A family. Interindividual variation in APAP glucuronidation is attributed in part to polymorphisms in UGT1As. However, evidence suggests that UGT2B15 may also be important. We evaluated, in a controlled feeding trial, whether APAP conjugation differed by UGT1A6 and UGT2B15 genotypes and whether supplementation of known dietary inducers of UGT (crucifers, soy, and citrus) modulated APAP glucuronidation compared with a diet devoid of fruits and vegetables (F&V). Healthy adults (n = 66) received 1000 mg of APAP orally on days 7 and 14 of each 2-week feeding period and collected saliva and urine over 12 h. Urinary recovery of the percentage of the APAP dose as free APAP was higher (P = 0.02), and the percentage as APAP glucuronide (APAPG) was lower (P = 0.004) in women. The percentage of APAP was higher among UGT1A6*1/*1 genotypes, relative to *1/*2 and *2/*2 genotypes (P = 0.045). For UGT2B15, the percentage of APAPG decreased (P < 0.0001) and that of APAP sulfate increased (P = 0.002) in an allelic dose-dependent manner across genotypes from *1/*1 to *2/*2. There was a significant diet × UGT2B15 genotype interaction for the APAPG ratio (APAPG/total metabolites × 100) (P = 0.03), with *1/*1 genotypes having an approximately 2-fold higher F&V to basal diet difference in response compared with *1/*2 and *2/*2 genotypes. Salivary APAP maximum concentration (C(max)) was significantly higher in women (P = 0.0003), with F&V (P = 0.003), and among UGT1A6*2/*2 and UGT2B15*1/*2 genotypes (P = 0.02 and 0.002, respectively). APAP half-life was longer in UGT2B15*2/*2 genotypes with F&V (P = 0.009). APAP glucuronidation was significantly influenced by the UGT2B15*2 polymorphism, supporting a role in vivo for UGT2B15 in APAP glucuronidation, whereas the contribution of UGT1A6*2 was modest. Selected F&V known to affect UGT activity led to greater glucuronidation and less sulfation.

Determinants of aspirin metabolism in healthy men and women: effects of dietary inducers of UDP-glucuronosyltransferases

BACKGROUND/AIMS

Interindividual variation in aspirin (ASA) metabolism is attributed to concomitant use of drugs or alcohol, urine pH, ethnicity, sex, and genetic variants in UDP-glucuronosyltransferases (UGT). Little is known about the effects of diet.

METHODS

We evaluated cross-sectionally whether urinary excretion of ASA and its metabolites [salicylic acid (SA), salicyluric acid (SUA) phenolic glucuronide (SUAPG), salicylic acid acyl glucuronide (SAAG) and salicylic acid phenolic glucuronide (SAPG)] differed by UGT1A6 genotype and dietary factors shown to induce UGT. Following oral treatment with 650 mg ASA, urine was collected over 8 h in 264 men and 264 women (21-45 years old).

RESULTS

There were statistically significant differences in metabolites excreted between sexes and ethnicities. Men excreted more SUA; women more ASA (p = 0.03), SA, SAAG and SAPG (p ≤ 0.001 for all). Compared to Caucasians, Asians excreted more ASA, SA and SAAG, and less SUA and SUAPG (p ≤ 0.03 for all); African-Americans excreted more SAAG and SAPG and less SUA (p ≤ 0.04). There was no effect of UGT1A6 genotypes. Increased ASA and decreased SUAPG excretion was observed with increased servings of vegetables (p = 0.008), specifically crucifers (p = 0.05).

CONCLUSION

Diet may influence the pharmacokinetics of ASA, but effects may be through modulation of glycine conjugation rather than glucuronidation.

DNA damage and repair: fruit and vegetable effects in a feeding trial

Epidemiologic studies have examined the association between fruit and vegetable (F&V) consumption and the risk of cancer. Several cancer-preventive mechanisms have been proposed, such as antioxidant properties and modulation of biotransformation enzyme activities; both may be associated with reducing DNA damage and hence the mutation rate. We investigated, in a randomized, controlled, crossover feeding trial, the effect of 10 servings/day of botanically defined F&V for 2 wk on endogenous DNA damage; resistance to gamma -irradiation damage; and DNA repair capacity in lymphocytes, measured by the Comet assay. We also explored the association between the UGT1A1*28 polymorphism and serum bilirubin concentrations and DNA damage and repair measures. Healthy men (n = 11) and women (n = 17), age 20 to 40 yr, provided blood samples at the end of each feeding period. Overall, F&V did not affect DNA damage and repair measures in lymphocytes. The number of UGT1A1*28 alleles was inversely associated with sensitivity to gamma -irradiation exposure and DNA repair capacity, but a biological mechanism to explain this association is unclear. A larger sample size is needed to investigate the association between bilirubin concentrations and endogenous DNA damage. With inconsistent findings in the literature, additional dietary intervention studies on the effect of F&V on DNA damage and repair are needed.

Dietary and demographic correlates of serum beta-glucuronidase activity

beta-glucuronidase, an acid hydrolase that deconjugates glucuronides, may increase cancer risk; however, little is known about factors associated with human beta -glucuronidase. Our objective was to examine whether dietary and demographic factors were associated with serum beta -glucuronidase activity. We conducted a cross-sectional study among 279 healthy men and women aged 20 to 40 yr. Diet, categorized by botanical families and nutrient intakes, was assessed from 3-day food records and a validated semiquantitative food frequency questionnaire. Demographic factors were directly measured or self-reported. Adjusted mean beta -glucuronidase activity across categories of exposure variables were calculated by multiple linear regression. Higher beta -glucuronidase activity was significantly associated with being male, older age (> or = 30 yr), non-Caucasian, overweight (> or = 25 kg/m(2)), and higher intakes of gamma-tocopherol. Conversely, lower beta -glucuronidase activity was significantly associated with higher intakes of calcium, iron, and magnesium. A suggestive decrease in beta -glucuronidase activity was observed for the botanical families Cruciferae, Rutaceae, Compositae, Roseaceae, and Umbelliferae, but tests for trend were not statistically significant. In conclusion, several dietary and nondietary factors were associated with beta -glucuronidase activity; however, confirmation of these associations are needed.

Modulation of human serum glutathione S-transferase A1/2 concentration by cruciferous vegetables in a controlled feeding study is influenced by GSTM1 and GSTT1 genotypes

Glutathione S-transferases (GST) detoxify a wide range of carcinogens. Isothiocyanates (ITC), from cruciferous vegetables, are substrates for and inducers of GST. GST variants may alter ITC clearance such that response to crucifers varies by genotype. In a randomized cross-over trial, we tested the hypothesis that changes in serum GSTA1/2 concentration in response to cruciferous vegetable feeding depends on GSTM1/GSTT1 genotype. Thirty-three men and 34 women (age 20-40 years) ate four 14-day controlled diets--basal (vegetable-free), basal supplemented with two different doses of crucifers ("single dose" and "double dose"), and single-dose cruciferous-plus-apiaceous vegetables--fed per kilogram of body weight. Fasting bloods from days 0, 7, 11, and 14 of each diet period were analyzed for serum GSTA1/2 by ELISA. GSTA1/2 increased with single- and double-dose cruciferous compared with basal diet (10% and 13%, respectively; P = 0.02 and 0.004), but cruciferous-plus-apiaceous did not differ from basal (P = 0.59). Overall, GSTA1/2 was higher in GSTM1-null/GSTT1-null than GSTM1+/GSTT1+ individuals (4,198 +/- 338 and 3,372 +/- 183 pg/mL; P = 0.03). The formal interaction of genotype-by-diet was not statistically significant, but the GSTA1/2 increase during the single-dose cruciferous diet was among GSTM1-null/GSTT1-null individuals (by 28%; P = 0.008), largely explained by GSTM1-null/GSTT1-null men (by 41%; P = 0.01). GSTA1/2 increased during the double-dose cruciferous diet in both GSTM1-null/GSTT1-null men (by 35%; P = 0.04) and GSTM1+/GSTT1+ men (by 26%; P = 0.01) but not in women. In summary, cruciferous vegetable supplementation increased GSTA1/2, but the effect was most marked in GSTM1-null/GSTT1-null men.

Abstract B99: Determinants of aspirin metabolism in healthy individuals

Regular use of aspirin is associated with lower colon cancer risk. High inter-individual variation in aspirin metabolism has been attributed to several factors, including sex, concomitant use of other drugs or alcohol, urine pH, ethnicity, and variants in metabolizing enzymes involved in glucuronidation of aspirin metabolites [i.e., UDP glucuronosyltransferases (UGT)]. However, little is known about the impact of other exposures, including dietary factors. Dietary constituents of citrus fruits, cruciferous vegetables and soy have been shown to induce UGT. Higher intakes may alter UGT activity and affect the ratio of aspirin metabolites excreted.

We evaluated, cross-sectionally, whether urinary excretion of aspirin [ASA] and its metabolites (salicylic acid [SA], salicyluric acid [SUA], salicyluric phonolic glucuronide [SUPG], salicyl acyl and phenolic acid glucuronides [SAG/SPG]) differed by UGT1A6 genotype and dietary factors. Following an oral dose of 650 mg aspirin, healthy men (N=264) and women (N=264), 20–40 years, collected urine over an 8-h period. Participant exclusion criteria included medical history of gastrointestinal, hepatic or renal disorders, and exposure to non-dietary factors known to influence biotransformation enzymes, e.g., medications, excessive alcohol, and smoking. FFQ data were available for 481 participants. Multiple linear regression was used to determine whether there were differences in aspirin metabolism by UGT1A6 genotype, or daily intake of protein, total fruit or vegetable intake, and soy, citrus and cruciferous vegetable intake, adjusted for body mass index (BMI), age, sex, ethnicity, urine volume and pH, and energy intake.

There were statistically significant differences in the ratios of metabolites excreted, (specific metabolite/sum of metabolites), between sexes and between ethnic groups. Men excreted more SUA (P&lt;0.001), and women excreted more SA and the glucuronides SAG/SPG (P≤0.001 for all 3). Compared to Caucasians, Asians excreted significantly more ASA, SA and SAG, and less SUA and SUPG (P≤0.03 for all), and African Americans excreted significantly more combined SAG/SPG, and less SUA (P≤0.04 for both). The interaction term for sex*ethnicity was significant for SUPG (P=0.006), with Caucasian men excreting the most, and Asian women excreting the least. Excretion of urinary aspirin metabolites did not differ statistically significantly between UGT1A6 genotypes (UGT1A6 *1/*1, *1/*2, and *2/*2). Increased ASA and decreased SUPG excretion was observed with increased servings of total vegetables (P=0.008 for both), and a trend toward significance with intake of cruciferous vegetables specifically (P=0.05 for both). A corresponding increase in SAG/SPG glucuronides was observed, but was not significant (P=0.40). There were no significant differences in metabolite excretion by soy or citrus fruit intake.

Of the factors evaluated, ethnicity and sex were the greatest, albeit modest, contributors to variability in aspirin metabolism (R2=2−13%), whereas UGT1A6 had no effect. Our results also suggest that diet may influence aspirin metabolism, but the effects do not appear to be via glucuronidation.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B99.

CYP1A2, GSTM1, and GSTT1 polymorphisms and diet effects on CYP1A2 activity in a crossover feeding trial

Cytochrome P-450 1A2 (CYP1A2) is a biotransformation enzyme that activates several procarcinogens. CYP1A2 is induced by cruciferous and inhibited by apiaceous vegetable intake. Using a randomized, crossover feeding trial in humans, we investigated the dose effects of cruciferous vegetables and the effects of any interaction between cruciferous and apiaceous vegetables on CYP1A2 activity. We also investigated whether response varied by CYP1A2*1F, GSTM1, and GSTT1 genotypes (glutathione S-transferases that metabolize crucifer constituents) and whether CYP1A2 activity rebounds after apiaceous vegetables are removed from the diet. Participants (N = 73), recruited based on genotypes, consumed four diets for two weeks each: low-phytochemical diet (basal), basal plus single dose of cruciferous (1C), basal plus double dose of cruciferous (2C), and basal plus single dose of cruciferous and apiaceous vegetables (1C+A). CYP1A2 activity was determined by urine caffeine tests administered at baseline and the end of each feeding period. Compared with basal diet, the 1C diet increased CYP1A2 activity (P < 0.0001) and the 2C diet resulted in further increases (P < 0.0001), with men experiencing greater dose-response than women. The 1C+A diet decreased CYP1A2 activity compared with the 1C and 2C diets (P < 0.0001 for both). Although there was no overall effect of CYP1A2*1F or GSTM1-null/GSTT1-null genotypes or genotype-by-diet interactions, there were significant diet response differences within each genotype. Additionally, CYP1A2 activity recovered modestly one day after the removal of apiaceous vegetables. These results suggest complex interactions among dietary patterns, genetic variation, and modulation of biotransformation that may not be apparent in observational studies.

Human gut bacterial communities are altered by addition of cruciferous vegetables to a controlled fruit- and vegetable-free diet

In the human gut, commensal bacteria metabolize food components that typically serve as energy sources. These components have the potential to influence gut bacterial community composition. Cruciferous vegetables, such as broccoli and cabbage, contain distinctive compounds that can be utilized by gut bacteria. For example, glucosinolates can be hydrolyzed by certain bacteria, and dietary fibers can be fermented by a range of species. We hypothesized that cruciferous vegetable consumption would alter growth of certain bacteria, thereby altering bacterial community composition. We tested this hypothesis in a randomized, crossover, controlled feeding study. Fecal samples were collected from 17 participants at the end of 2 14-d intake periods: a low-phytochemical, low-fiber basal diet (i.e. refined grains without fruits or vegetables) and a high ("double") cruciferous vegetable diet [basal diet + 14 g cruciferous vegetables/(kg body weightd)]. Fecal bacterial composition was analyzed by the terminal restriction fragment length polymorphism (tRFLP) method using the bacterial 16S ribosomal RNA gene and nucleotide sequencing. Using blocked multi-response permutation procedures analysis, we found that overall bacterial community composition differed between the 2 consumption periods (delta = 0.603; P = 0.011). The bacterial community response to cruciferous vegetables was individual-specific, as revealed by nonmetric multidimensional scaling ordination analysis. Specific tRFLP fragments that characterized each of the diets were identified using indicator species analysis. Putative species corresponding to these fragments were identified through gene sequencing as Eubacterium hallii, Phascolarctobacterium faecium, Burkholderiales spp., Alistipes putredinis, and Eggerthella spp. In conclusion, human gut bacterial community composition was altered by cruciferous vegetable consumption, which could ultimately influence gut metabolism of bioactive food components and host exposure to these compounds.

Pulmonary dysfunction in systemic lupus erythematosus and anti‐phospholipid syndrome patients

OBJECTIVE

To assess and compare parameters of pulmonary function in systemic lupus erythematosus (SLE) and anti-phospholipid syndrome (APS) patients.

METHODS

Consecutive patients (n = 74) who were free of respiratory symptoms were divided into four groups: 1) SLE (n = 23); 2) SLE with anti-phospholipid antibodies (aPL) (n = 18); 3) SLE with APS (n = 20); and 4) primary APS (PAPS) (n = 13). Pulmonary function testing, single breath diffusion capacity of carbon monoxide (DLCO/SB) and echocardiography studies were performed. Induced sputum cytology was analysed.

RESULTS

Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and DLCO were significantly reduced in SLE compared to PAPS patients (p = 0.039; p = 0.017; p = 0.029, respectively). Elevated pulmonary arterial pressure was observed in two patients with SLE and aPL and in two with SLE and APS. Lymphocyte and eosinophil counts in induced sputum showed no significant differences; however, a trend towards lower CD4 counts in SLE vs. PAPS was noted (p = 0.086), while in patients with both SLE and APS, a low CD4/CD8 ratio was seen. Patients with APS were older than patients without APS (47.12+/-14.86 vs. 34.29+/-12.6, p = 0.0001), while SLE patients were younger than PAPS patients (38.19+/-14.68 vs. 48.53+/-13.97, p = 0.023).

CONCLUSION

Abnormal pulmonary functions tests were detected frequently in asymptomatic patients with SLE or PAPS. Although SLE patients were younger, pulmonary function was significantly more impaired in SLE as compared to PAPS patients.

Cruciferous vegetable feeding alters UGT1A1 activity: diet- and genotype-dependent changes in serum bilirubin in a controlled feeding trial

Chemoprevention by isothiocyanates from cruciferous vegetables occurs partly through up-regulation of phase II conjugating enzymes, such as UDP-glucuronosyltransferases (UGT). UGT1A1 glucuronidates bilirubin, estrogens, and several dietary carcinogens. The UGT1A1*28 polymorphism reduces transcription compared with the wild-type, resulting in decreased enzyme activity. Isothiocyanates are metabolized by glutathione S-transferases (GST); variants may alter isothiocyanate clearance such that response to crucifers may vary by genotype. We evaluated, in a randomized, controlled, crossover feeding trial in humans (n = 70), three test diets (single- and double-"dose" cruciferous and cruciferous plus apiaceous) compared with a fruit and vegetable-free basal diet. We measured serum bilirubin concentrations on days 0, 7, 11, and 14 of each 2-week feeding period to monitor UGT1A1 activity and determined effects of UGT1A1*28 and GSTM1/GSTT1-null variants on response. Aggregate bilirubin response to all vegetable-containing diets was statistically significantly lower compared with the basal diet (P < 0.03 for all). Within each UGT1A1 genotype, lower bilirubin concentrations were seen in *1/*1 in both single- and double-dose cruciferous diets compared with basal (P < 0.03 for both); *1/*28 in double-dose cruciferous and cruciferous plus apiaceous compared with basal, and cruciferous plus apiaceous compared with single-dose cruciferous (P < 0.02 for all); and *28/*28 in all vegetable-containing diets compared with basal (P < 0.02 for all). Evaluation of the effects of diet stratified by GST genotype revealed some statistically significant genotypic differences; however, the magnitude was similar and not statistically significant between genotypes. These results may have implications for altering carcinogen metabolism through dietary intervention, particularly among UGT1A1*28/*28 individuals.

Citrus fruit intake is associated with lower serum bilirubin concentration among women with the UGT1A1*28 polymorphism

UDP-glucuronosyltransferase (UGT) 1A1 glucuronidates bilirubin, estrogens, and xenobiotic compounds. The UGT1A1*28 polymorphism results in lower promoter activity due to 7 thymine-adenine (TA) repeats rather than the more common 6 TA repeats. Previously, we showed that serum bilirubin, a marker of UGT1A1 activity, was lower among individuals homozygous for the UGT1A1*28 polymorphism (7/7) when randomized to a high fruit and vegetable (F&V) diet, whereas there was no effect in individuals with the wild-type (6/6) and heterozygous (6/7) genotypes. Our objective here was to determine if we could detect genotype x diet interactions on bilirubin concentrations in an observational study. Healthy nonsmoking men (n = 146) and women (n = 147), recruited from the Seattle area, provided blood samples for genotyping and bilirubin measurements. We used multiple linear regression to assess the relationships among UGT1A1 genotype, bilirubin concentrations, and consumption of specific F&V [cruciferous vegetables, citrus fruits, and soy foods (n = 268)] based on FFQ and F&V from 6 botanical families [Cruciferae, Rosaceae, Rutaceae, Umbelliferae, Solanaceae, and Leguminosae (n = 261)] based on 3-d food records. We observed a significant interaction of UGT1A1 genotype and citrus consumption among women. Women with the 7/7 genotype who consumed > or = 0.5 daily servings of citrus fruit or foods from the Rutaceae botanical family had approximately 30% lower serum bilirubin than those with the same genotype who consumed less, whereas 6/6 and 6/7 genotypes did not differ by consumption (P for interaction = 0.006 and 0.03, respectively). These results suggest that citrus consumption may increase UGT1A1 activity among women with the 7/7 genotype.

Serum beta-glucuronidase activity in response to fruit and vegetable supplementation: a controlled feeding study

BACKGROUND

Fruit and vegetable (F&V) intake may lower the risk of some cancers. One hypothesized, but understudied, chemopreventive mechanism is that plant food constituents inhibit beta-glucuronidase, an acid hydrolase that deconjugates glucuronides.

METHODS

We conducted a crossover feeding trial in 63 healthy women and men ages 20 to 40 years to examine the effect of diet on serum beta-glucuronidase activity. Participants were randomized to two 2-week experimental diets with an intervening washout period: a diet high in selected citrus fruit, crucifers, and soy (F&V) and a diet devoid of fruits, vegetables, and soy (basal). Serum beta-glucuronidase activity was measured during the preintervention, F&V, and basal periods. Linear mixed models were used to obtain effect estimates and 95% confidence intervals (95% CI).

RESULTS

We observed statistically significantly higher beta-glucuronidase activity during the F&V than the basal diet (ratio, F&V versus basal diet, 1.09; 95% CI, 1.05-1.13; P < 0.01). These results were probably due to decreased beta-glucuronidase activity during the basal diet (ratio, basal period versus preintervention, 0.93; 95% CI, 0.87-0.98; P = 0.01) rather than increased enzyme activity during the F&V diet (ratio, F&V period versus preintervention, 1.01; 95% CI, 0.96-1.06; P = 0.64). Response to the experimental diet did not differ by sex (P(interaction) = 0.30), but there was a suggestion of a short-term diet effect at 8 versus 15 days (P(interaction) = 0.06).

CONCLUSION

This intervention of selected F&V did not lower beta-glucuronidase activity. Further investigation is needed regarding what other foods and phytochemicals may influence beta-glucuronidase activity and effect modifiers of this relation.

UGT1A6 polymorphism and salicylic acid glucuronidation following aspirin

OBJECTIVES

In vivo, aspirin (acetylsalicylic acid) is rapidly deacetylated to form salicylic acid, which then undergoes primary or secondary glucuronidation catalyzed by UDP-glucuronosyltransferases (UGTs). The variant UGT1A6*2 (T181A, R184S) is associated with altered enzyme function. Our objective was to compare salicylic acid glucuronidation in individuals with different UGT1A6 genotypes.

METHODS

Following orally dosing with 650 mg aspirin, saliva and urine samples were collected over a period of 24 h from healthy individuals with homozygous wild-type UGT1A6 *1/*1 (n=19) and homozygous variant UGT1A6 *2/*2 (T181A, R184S) (n=9) genotypes.

RESULTS

No statistically significant differences were observed in salivary pharmacokinetic parameters. Urinary excretion of the sum of aspirin and its metabolites (salicyluric acid, salicyluric acid phenolic glucuronide, salicyl phenolic glucuronide, salicyl acyl glucuronide, salicylic acid) during the early period of 2-4 h of collection was significantly lower in UGT1A6 *1/*1 than in UGT1A6 *2/*2 individuals. Further, UGT1A6 *1/*1 individuals excreted a lower percentage of aspirin and its metabolites in the first 12 h and a greater percentage after 12 h than UGT1A6 *2/*2 individuals.

CONCLUSIONS

The variant UGT1A6*2 or polymorphisms in other UGTs that are in linkage disequilibrium with UGT1A6*2 may confer more rapid glucuronidation of salicylic acid than the wild-type UGT1A6 *1/*1.

UGT1A1 polymorphism is associated with serum bilirubin concentrations in a randomized, controlled, fruit and vegetable feeding trial

UDP-glucuronosyltransferase (UGT) 1A1 glucuronidates bilirubin, estrogens, and exogenous compounds, including dietary carcinogens. The UGT1A1*28 polymorphism, characterized by variation in the number of thymine-adenine repeats in the promoter region, modulates UGT1A1 transcription. Observational and in vitro studies suggest that certain phytochemicals may increase UGT activity. We investigated, in a randomized, controlled, crossover feeding trial, whether approximately 10 servings/d (doses adjusted for body weight) of crucifers, soy, and citrus for 2 wk compared with a fruit- and vegetable-free basal diet affected UGT1A1 activity as measured by serum bilirubin concentrations and whether effects were modulated by the UGT1A1*28 polymorphism. Healthy men (n = 32) and women (n = 31), aged 20-40 y, enrolled based on UGT1A1 genotype, completed the study. We measured bilirubin in blood collected at d 8 and d 15 of each feeding period. Overall, fruit and vegetables (F&V) did not affect serum bilirubin; however, among 7/7 individuals, d 8 total (P = 0.057) and indirect (unconjugated) (P = 0.051) bilirubin tended to be lower when individuals consumed the F&V diet (28.97 +/- 2.36 micromol/L and 25.97 +/- 2.15 micromol/L) compared with the basal diet (32.46 +/- 2.63 micromol/L and 29.31 +/- 2.43 micromol/L). We no longer detected this difference at d 15, by which time bilirubin had also decreased when participants consumed the basal diet. Additionally, intervention effects on bilirubin were restricted to women with 7/7 genotype (P = 0.002). These results suggest that serum bilirubin glucuronidation is modulated by dietary intervention, but factors such as UGT1A1 genotype and sex may affect the response to diet.

Diagnosis of intrathoracic lesions: are sequential fine-needle aspiration (FNA) and core needle biopsy (CNB) combined better than either investigation alone?

AIM

To assess the diagnostic accuracy of sequential computed tomography (CT)-guided percutaneous fine-needle aspiration (FNA) and core-needle biopsy (CNB) in comparison with FNA and CNB performed separately for diagnosing intrathoracic lesions.

SUBJECTS AND METHODS

Five hundred and eighty-two consecutive patients with thoracic lesions who underwent same-session sequential CT-guided FNA and CNB procedures were studied. The final diagnosis, which was achieved by either agreement of percutaneous procedures with clinical follow-up, bronchoscopy or thoracotomy was available for all cases. The diagnostic yield of the combined FNA+CNB procedures was compared with that of each alone.

RESULTS

Adequate samples were obtained in 541 (93%) of FNAs and 513 (88%) of CNBs. Of 582 lesions, 419 (72%) were malignant and 163 (28%) were benign. For malignant lesions, the sensitivity, specificity and accuracy of the procedures were: 376/419 (89.7%), 136/163 (83.4%), and 88% for FNA; 317/419 (75.6%), 138/163 (84.7%), and 78% for CNB; 400/419 (95.5%), 154/163 (94.5%), and 95% for FNA+CNB. The sequential procedures showed significantly better sensitivity, specificity and accuracy compared with either FNA or CNB separately (p<0.003). For the 163 benign lesions, 76 (47%) had a specific benign pathological diagnosis. The diagnosis was obtained in 16/76 (21%) by FNA, in 54/76 (71%) by CNB, and in 60/76 (79%) by FNA+CNB. There was no significant difference between the results of the sequential procedures and CNB alone (p>0.05).

CONCLUSIONS

Sequential FNA and CNB improve the diagnostic accuracy of percutaneous CT-guided procedures in malignant lesions. There was only mild improvement, which was not statistically significant, for the diagnosis of benign specific lesions by the sequential procedures compared with the yield of CNB alone.

Factors associated with self-evaluated severity of illness and quality of life in male Israeli asthmatic soldiers

OBJECTIVE

To evaluate whether the asthmatic condition and quality of life of male asthmatic Israeli soldiers deteriorate during army service.

METHOD

We retrospectively assessed 178 asthmatic soldiers during service using an adapted version of the Mini Asthma Quality of Life Questionnaire, and compared it to their condition before service. The participants responded additionally to questionnaires assessing psychosocial resources and adjustment to illness.

RESULTS

The self-evaluated degree of asthma disease severity (SEDOAD) of the participants deteriorated in the army compared to before service. Soldiers with mild SEDOAD during service, compared to soldiers with severe (and in most cases also moderate) SEDOAD, had less severe medically evaluated and self-evaluated asthma before service. Mild SEDOAD participants showed, additionally, lower inclination towards active seeking of asthma-related information, more favorable health care-related attitudes, less unfavorable effects of their illness on military and extra-military functioning, greater reported pre-enlistment optimism, and a greater belief in their ability to cope successfully with their asthma during service.

CONCLUSION

SEDOAD and the quality of life during service are associated not only with pre-enlistment asthma severity, but also with the manner in which the soldier perceives the influence of the illness on his health condition, and the manner in which he copes with this influence.

Induced sputum for diagnosing Pneumocystis carinii pneumonia in HIV patients: new data, new issues

The complexity of bronchoalveolar lavage (BAL) has motivated the search for noninvasive methodology to retrieve specimens for detecting the presence of various pulmonary diseases. Induced sputum (IS) has been shown to be a reliable tool in terms of sensitivity and specificity comparable to BAL. Investigators from institutions worldwide have published several reports providing evidence in support of one or the other or a combination of both approaches. Among them are studies demonstrating the sensitivity and specificity of IS in diagnosing Pneumocystis carinii pneumonia (PCP) in patients with acquired immunodeficiency syndrome (AIDS). In 1996, highly active antiretroviral therapy was introduced for routine use and the morbidity from opportunistic infections decreased sharply. An earlier study showed that cost-effectiveness depends on the prevalence of a given condition in the population. More recent studies have confirmed that prophylaxis against PCP can be stopped after increasing the CD4 cell count, thus reducing the attractiveness of IS as a preferred method for monitoring the course of disease. This review presents a brief description of the evolution of the bronchoalveolar lavage versus induced sputum controversy and reconsiders the strengths and weaknesses of the earlier arguments in light of newer data that have emerged with regard to Pneumocystis carinii pneumonia in acquired immunodeficiency syndrome.

Correlative study of preoperative transthoracic core cutting needle biopsy of focal thoracic lesions and thoracotomy findings

We conducted a retrospective study to determine the clinical utility of percutaneous core needle biopsy (PCNBx) in 36 patients with peripheral focal chest lesions who later underwent thoracic surgery for diagnostic or therapeutic purposes. PCNBx provided adequate material in 31/36 cases, giving an overall sample yield of 86.1%. PCNBx diagnosis was confirmed by surgery in 27/31 patients, giving a sensitivity of 91.6% and a specificity of 87.5%. In 4 patients, the lesions were misdiagnosed by PCNBx. In 5 patients with benign processes, surgical intervention could have been avoided, according to PCNBx results. The rate of PCNBx-induced pneumothorax was 11%. Radiologically guided PCNBx is an easy and safe procedure that can provide important preoperative diagnostic information and can circumvent the need for exploratory diagnostic surgery in cases of benign lesions. PCNBx also allows better preoperative planning in cases of malignancy.