Nicholas O Davidson

Washington University in St. Louis, San Luis, Missouri, United States

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Publications (203)1518.08 Total impact

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    ABSTRACT: The mechanisms by which mucosal homeostasis is maintained are of central importance to inflammatory bowel disease. Critical to these processes is the intestinal epithelial cell (IEC), which regulates immune responses at the interface between the commensal microbiota and the host. CD1d presents self and microbial lipid antigens to natural killer T (NKT) cells, which are involved in the pathogenesis of colitis in animal models and human inflammatory bowel disease. As CD1d crosslinking on model IECs results in the production of the important regulatory cytokine interleukin (IL)-10 (ref. 9), decreased epithelial CD1d expression-as observed in inflammatory bowel disease-may contribute substantially to intestinal inflammation. Here we show in mice that whereas bone-marrow-derived CD1d signals contribute to NKT-cell-mediated intestinal inflammation, engagement of epithelial CD1d elicits protective effects through the activation of STAT3 and STAT3-dependent transcription of IL-10, heat shock protein 110 (HSP110; also known as HSP105), and CD1d itself. All of these epithelial elements are critically involved in controlling CD1d-mediated intestinal inflammation. This is demonstrated by severe NKT-cell-mediated colitis upon IEC-specific deletion of IL-10, CD1d, and its critical regulator microsomal triglyceride transfer protein (MTP), as well as deletion of HSP110 in the radioresistant compartment. Our studies thus uncover a novel pathway of IEC-dependent regulation of mucosal homeostasis and highlight a critical role of IL-10 in the intestinal epithelium, with broad implications for diseases such as inflammatory bowel disease.
    Nature 04/2014; · 38.60 Impact Factor
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    ABSTRACT: Objective To assess hospital and geographic variability in 30-day mortality after surgery for CRC and examine the extent to which sociodemographic, area-level, clinical, tumor, treatment, and hospital characteristics were associated with increased likelihood of 30-day mortality in a population-based sample of older CRC patients.Data Sources/Study SettingLinked Surveillance Epidemiology End Results (SEER) and Medicare data from 47,459 CRC patients aged 66 years or older who underwent surgical resection between 2000 and 2005, resided in 13,182 census tracts, and were treated in 1,447 hospitals.Study DesignAn observational study using multilevel logistic regression to identify hospital- and patient-level predictors of and variability in 30-day mortality.Data Collection/Extraction Methods We extracted sociodemographic, clinical, tumor, treatment, hospital, and geographic characteristics from Medicare claims, SEER, and census data.Principal FindingsOf 47,459 CRC patients, 6.6 percent died within 30 days following surgery. Adjusted variability in 30-day mortality existed across residential census tracts (predicted mortality range: 2.7–12.3 percent) and hospitals (predicted mortality range: 2.5–10.5 percent). Higher risk of death within 30 days was observed for CRC patients age 85+ (12.7 percent), census-tract poverty rate >20 percent (8.0 percent), two or more comorbid conditions (8.8 percent), stage IV at diagnosis (15.1 percent), undifferentiated tumors (11.6 percent), and emergency surgery (12.8 percent).Conclusions Substantial, but similar variability was observed across census tracts and hospitals in 30-day mortality following surgery for CRC in patients 66 years and older. Risk of 30-day mortality is driven not only by patient and hospital characteristics but also by larger social and economic factors that characterize geographic areas.
    Health Services Research 03/2014; · 2.29 Impact Factor
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    ABSTRACT: Comanagement of surgical patients has increased, but information regarding detailed characteristics of patients receiving comanagement during hospitalization for colorectal cancer (CRC) surgery is lacking. To examine the use of and characteristics associated with comanagement of patients hospitalized for CRC surgery. This study used a population-based cross-sectional design. We used the linked 2000 to 2005 Surveillance, Epidemiology, and End Results and Medicare claims data. We included 37,065 patients aged 66 years or older, hospitalized for definitive CRC surgery following stage I to III diagnosis. The outcome of interest was comanagement during hospitalization for CRC surgery, and we examined the association between several patient and hospital characteristics. Comanagement was defined as having a relevant physician (ie, internal medicine hospitalist/generalist) submit a claim for evaluation and management services on 70% or more of the days of hospitalization of the patient. During hospitalization for CRC surgery, 27.6% of patients were comanaged, but this percentage varied widely across hospitals (from 1.9% to 83.2%). Several patient and hospital characteristics were associated with the use of comanaged care, of which important characteristics included older age at diagnosis, presence of comorbidity, emergency surgery, and hospital volume. Extensive variability existed in comanagement use across patients and hospitals, likely reflecting the lack of evidence for its clinical effectiveness. Journal of Hospital Medicine 2014. © 2014 Society of Hospital Medicine.
    Journal of Hospital Medicine 02/2014; · 1.40 Impact Factor
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    ABSTRACT: Previous studies demonstrated that L-Fabp knockout mice are more susceptible to LD induced gallstones because of altered hepatic cholesterol metabolism and increased canalicular cholesterol secretion. Other studies demonstrated that liver-specific deletion of microsomal triglyceride transfer protein (Mttp-LKO) reduced lithogenic diet (LD) induced gallstone formation by increasing biliary phospholipid secretion. Here we show that mice with combined deletion (ie DKO mice) are protected from LD induced gallstone formation. Following two weeks LD feeding, 73% of wild-type (WT) and 100% of L-Fabp knockout mice developed gallstones versus 18% of Mttp-LKO and 23% of DKO mice. This phenotype was recapitulated in both WT and L-Fabp knockout mice treated with an Mttp antisense oligonucleotide (M-ASO). Biliary cholesterol secretion was increased in LD fed L-Fabp knockout mice and decreased in DKO mice. However, phospholipid secretion was unchanged in LD fed Mttp-LKO and DKO mice as well as in M-ASO treated mice. Expression of the canalicular export pump ABCG5/G8 was reduced in LD fed DKO mice and in M-ASO treated L-Fabp knockout mice. We conclude that liver-specific Mttp deletion not only eliminates apical lipoprotein secretion from hepatocytes but also attenuates canalicular cholesterol secretion, which in turn decreases LD induced gallstone susceptibility.
    The Journal of Lipid Research 01/2014; · 4.39 Impact Factor
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    ABSTRACT: Bile acid synthesis is regulated by nuclear receptors including farnesoid X receptor (FXR) and small heterodimer partner (SHP), and by fibroblast growth factor15/19 (FGF15/19). Because bile acid synthesis involves amino acid conjugation, we hypothesized that hepatic cysteine sulfinic acid decarboxylase (CSAD) (a key enzyme in taurine synthesis) is regulated by bile acids. To investigate CSAD regulation by bile acids and CSAD regulatory mechanisms. Mice were fed a control diet or a diet supplemented with either 0.5% cholate or 2% cholestyramine. To gain mechanistic insight into CSAD regulation, we utilized GW4064 (FXR agonist), FGF19, or T-0901317 (LXR agonist) and Shp(-/-) mice. Tissue mRNA expression was determined by qRT-PCR. Amino acids were measured by HPLC. Mice supplemented with dietary cholate exhibited reduced hepatic CSAD mRNA expression while those receiving cholestyramine exhibited increased hepatic CSAD mRNA expression. Activation of FXR suppressed CSAD mRNA expression whereas hepatic CSAD mRNA expression was increased in Shp(-/-) mice. Hepatic hypotaurine concentration (the product of CSAD) was higher in Shp(-/-) mice with a corresponding increase in serum (but not hepatic) taurine-conjugated bile acids. FGF19 administration suppressed hepatic CYP7A1 mRNA but did not change CSAD mRNA expression. LXR activation induced CYP7A1 mRNA yet failed to induce CSAD mRNA expression. CSAD mRNA expression is physiologically regulated by bile acids in a feedback fashion via mechanisms involving SHP and FXR but not FGF15/19 or LXR. These novel findings implicate bile acids as regulators of CSAD mRNA via mechanisms shared in part with CYP7A1.
    Hepatology Research 08/2013; · 2.07 Impact Factor
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    ABSTRACT: Evidence suggests a relationship between dietary fat intake, obesity and colorectal cancer, implying a role for fatty acid (FA) metabolism in intestinal tumorigenesis that is incompletely understood. Liver fatty acid binding protein (L-Fabp), a dominant intestinal FA binding protein, regulates intestinal FA trafficking and metabolism and L-Fabp deletion attenuates diet-induced obesity. Here we examined whether changes in intestinal FA metabolism following L-Fabp deletion modify adenoma development in ApcMin/+ mice. Compound L-Fabp-/-ApcMin/+ mice were generated and fed a 10% fat diet balanced equally between saturated, monounsaturated and polyunsaturated fat. L-Fabp-/-ApcMin/+ mice displayed significant reductions in adenoma number and total polyp area compared to ApcMin/+controls, reflecting a significant shift in distribution toward smaller polyps. Adenomas from L-Fabp-/-ApcMin/+ mice exhibited reductions in cellular proliferation, high-grade dysplasia and nuclear β-catenin translocation. Intestinal FA content was increased in L-Fabp-/-ApcMin/+ mice and lipidomic profiling of intestinal mucosa revealed significant shifts to polyunsaturated FA species with reduced saturated FA species. L-Fabp-/-ApcMin/+mice also demonstrated corresponding changes in mRNA expression of enzymes involved in FA elongation and desaturation. Furthermore, adenomas from L-Fabp-/-ApcMin/+mice displayed significant reductions in mRNA abundance of nuclear hormone receptors involved in cellular proliferation and in enzymes involved in lipogenesis. These findings collectively implicate L-Fabp as an important genetic modifier of intestinal tumorigenesis and identify FA trafficking and metabolic compartmentalization as an important pathway linking dietary fat intake, obesity and intestinal tumor formation.
    Cancer Prevention Research 08/2013; · 4.89 Impact Factor
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    ABSTRACT: BACKGROUND: Using 1998-2005 SEER-Medicare data, we examined the effect of diagnostic and treatment delays on all-cause and colorectal cancer (CRC)-specific death among US adults aged ≥ 66 years with invasive colon or rectal cancer. We hypothesized that longer delays would be associated with a greater risk of death. METHODS: We defined diagnostic and treatment delays, respectively, as days between (1) initial medical consult for CRC symptoms and pathologically confirmed diagnosis (maximum: 365 days) and (2) pathologically confirmed diagnosis and treatment (maximum: 120 days). Cases (CRC deaths) and controls (deaths due to other causes or censored) were matched on survival time. Logistic regression analyses adjusted for sociodemographic, tumor, and treatment factors. RESULTS: Median diagnostic delays were 60 (colon) and 40 (rectal) days and treatment delays were 13 (colon) and 16 (rectal) days in 10,663 patients. Colon cancer patients with the longest diagnostic delays (8-12 months vs. 14-59 days) had higher odds of all-cause (aOR: 1.31 CI: 1.08-1.58), but not CRC-specific death. Colon cancer patients with the shortest treatment delays (<1 vs. 1-2 weeks) had higher odds of all-cause (aOR: 1.23 CI: 1.01-1.49), but not CRC-specific death. Among rectal cancer patients, delays were not associated with risk of all-cause or CRC-specific death. CONCLUSIONS: Longer delays of up to 1 year after symptom onset and 120 days for treatment did not increase odds of CRC-specific death. There may be little clinical benefit in detecting and treating existing symptomatic disease earlier. Screening prior to symptom onset must remain the primary goal to reduce CRC incidence, morbidity, and mortality.
    Cancer Causes and Control 02/2013; · 3.20 Impact Factor
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    ABSTRACT: Activation of hepatic stellate cells (HSCs) is crucial to the development of fibrosis in nonalcoholic fatty liver disease. Quiescent HSCs contain lipid droplets (LDs), whose depletion upon activation induces a fibrogenic gene program. Here we show that liver fatty acid-binding protein (L-Fabp), an abundant cytosolic protein that modulates fatty acid (FA) metabolism in enterocytes and hepatocytes also modulates HSC FA utilization and in turn regulates the fibrogenic program. L-Fabp expression decreased 10-fold following HSC activation, concomitant with depletion of LDs. Primary HSCs isolated from L-FABP(-/-) mice contain fewer LDs than wild type (WT) HSCs, and exhibit upregulated expression of genes involved in HSC activation. Adenoviral L-Fabp transduction inhibited activation of passaged WT HSCs and increased both the expression of prolipogenic genes and also augmented intracellular lipid accumulation, including triglyceride and FA, predominantly palmitate. Freshly isolated HSCs from L-FABP(-/-) mice correspondingly exhibited decreased palmitate in the free FA pool. To investigate whether L-FABP deletion promotes HSC activation in vivo, we fed L-FABP(-/-) and WT mice a high fat diet supplemented with trans-fatty acids and fructose (TFF). TFF-fed L-FABP(-/-) mice exhibited reduced hepatic steatosis along with decreased LD abundance and size compared to WT mice. In addition, TFF-fed L-FABP(-/-) mice exhibited decreased hepatic fibrosis, with reduced expression of fibrogenic genes, compared to WT mice. Conclusion: L-FABP deletion attenuates both diet-induced hepatic steatosis and fibrogenesis, despite the observation that L-Fabp paradoxically promotes FA and LD accumulation and inhibits HSC activation in vitro. These findings highlight the importance of cell-specific modulation of hepatic lipid metabolism in promoting fibrogenesis in nonalcoholic fatty liver disease. (HEPATOLOGY 2013.).
    Hepatology 02/2013; · 12.00 Impact Factor
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    Soghra Jarvandi, Nicholas O Davidson, Mario Schootman
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    ABSTRACT: Poor diet increases the risk of both colorectal cancer and type 2 diabetes. We investigated the role of diet in the association between diabetes and colorectal cancer. We analyzed data from 484,020 individuals, aged 50-71 years who participated in the prospective National Institutes of Health-AARP Diet and Health Study and were cancer free at baseline (1995-1996). History of diabetes was self-reported. Diet quality was measured with the Healthy Eating Index-2005 (HEI-2005), using a self-administered food-frequency questionnaire. Cox regression models were constructed to estimate the hazard ratios (HR) and 95% confidence intervals (CI) of first primary incident colorectal cancer, overall and by anatomical location. During an average follow-up of 9.2 years, we identified 7,598 new cases of colorectal cancer. After controlling for non-dietary confounders, diabetes was associated with increased risk of colorectal cancer (HR 1.27, 95% CI: 1.18, 1.36). Further adjustment for diet quality did not attenuate this association. Diabetes was associated with a HR of 1.23 (95% CI: 1.07, 1.40) in individuals with good diet (quartile 4 of HEI-2005) and 1.58 (95% CI: 1.34, 1.86) in those with poor diet (quartile 1 of HEI-2005), compared to those with no diabetes and good diet. Moreover, diabetes was associated with a stronger risk of proximal than distal colon cancer (HR: 1.33 vs. HR: 1.20), while poor diet was associated with a weaker risk of proximal colon cancer (HR: 1.18 vs. HR: 1.46). Diabetes and poor diet, independently and additively are associated with the increased risk of colorectal cancer.
    PLoS ONE 01/2013; 8(9):e74616. · 3.73 Impact Factor
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    ABSTRACT: Gut derived lipid factors have been implicated in systemic injury and inflammation but the precise pathways involved are unknown. In addition, dietary fat intake and obesity are independent risk factors for the development of colorectal cancer. Here we studied the severity of experimental colitis and the development of colitis associated cancer (CAC) in mice with an inducible block in chylomicron secretion and fat malabsorption, following intestine-specific deletion of microsomal triglyceride transfer protein (Mttp-IKO). Mttp-IKO mice exhibited more severe injury with ∼90% mortality following dextran sodium sulfate (DSS) induced colitis, compared to <20% in controls. Intestinal permeability was increased in Mttp-IKO mice compared to controls, both at baseline and after DSS administration, in association with increased circulating levels of TNFα. DSS treatment increased colonic mRNA expression of IL-1β and IL-17A as well as inflammasome expression in both genotypes, but the abundance of TNFα was selectively increased in DSS treated Mttp-IKO mice. There was a 2-fold increase in colonic tumor burden in Mttp-IKO mice following azoxymethane/DSS treatment, which was associated with increased colonic inflammation as well as alterations in cytokine expression. To examine the pathways by which alterations in fatty acid abundance might interact with cytokine signaling to regulate colonic epithelial growth, we used primary murine myofibroblasts to demonstrate that palmitate induced expression of amphiregulin and epiregulin and augmented the increase in both of these growth mediators when added to IL-1βor to TNFα. These studies demonstrate that Mttp-IKO mice, despite absorbing virtually no dietary fat, exhibit augmented fatty acid dependent signaling that in turn exacerbates colonic injury and increases tumor formation.
    PLoS ONE 01/2013; 8(6):e67819. · 3.73 Impact Factor
  • Thomas A Kerr, Nicholas O Davidson
    Hepatology 11/2012; 56(5):1995-8. · 12.00 Impact Factor
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    ABSTRACT: The unfolded protein response (UPR) is a signaling pathway required to maintain endoplasmic reticulum (ER) homeostasis and hepatic lipid metabolism. Here, we identify an essential role for the inositol-requiring transmembrane kinase/endoribonuclease 1α (IRE1α)-X box binding protein 1 (XBP1) arm of the UPR in regulation of hepatic very low-density lipoprotein (VLDL) assembly and secretion. Hepatocyte-specific deletion of Ire1α reduces lipid partitioning into the ER lumen and impairs the assembly of triglyceride (TG)-rich VLDL but does not affect TG synthesis, de novo lipogenesis, or the synthesis or secretion of apolipoprotein B (apoB). The defect in VLDL assembly is, at least in part, due to decreased microsomal triglyceride-transfer protein (MTP) activity resulting from reduced protein disulfide isomerase (PDI) expression. Collectively, our findings reveal a key role for the IRE1α-XBP1s-PDI axis in linking ER homeostasis with regulation of VLDL production and hepatic lipid homeostasis that may provide a therapeutic target for disorders of lipid metabolism.
    Cell metabolism 10/2012; 16(4):473-86. · 17.35 Impact Factor
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    ABSTRACT: Intestinal apolipoprotein B (apo B) mRNA undergoes C-to-U editing, mediated by the catalytic deaminase apobec-1, which results in translation of apoB48. Apobec1 ko mice produce only apoB100 and secrete larger chylomicron particles than observed in wild type (WT) mice. Here we show that transgenic rescue of intestinal apobec-1 expression (Apobec1Int/O) restores C-to-U RNA editing of apoB mRNA in vivo including the canonical site at position 6666 and also at approximately 20 other newly identified downstream sites present in WT mice. The small intestine of Apobec1Int/O mice produces only apoB48, while the liver produces only apoB100. Serum chylomicron particles were smaller in Apobec1Int/O, compared to those from Apobec1 ko mice and the predominant fraction of serum apoB48 in Apobec1Int/O mice migrated in lipoproteins smaller than chylomicrons, even when these mice were fed a high fat diet. Since apoB48 arises exclusively from the intestine in Apobec1Int/O mice and intestinal apoB48 synthesis and secretion rates were comparable to WT mice, we were able to infer the major sites of origin of serum apoB48 in WT mice. Our findings imply that less than 25% of serum apoB48 in WT mice arises from the intestine, with the majority originating from the liver.
    The Journal of Lipid Research 09/2012; · 4.39 Impact Factor
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    ABSTRACT: Environmental agents and genetic variants can induce heritable epigenetic changes that affect phenotypic variation and disease risk in many species. These transgenerational effects challenge conventional understanding about the modes and mechanisms of inheritance, but their molecular basis is poorly understood. The Deadend1 (Dnd1) gene enhances susceptibility to testicular germ cell tumors (TGCTs) in mice, in part by interacting epigenetically with other TGCT modifier genes in previous generations. Sequence homology to A1cf, the RNA-binding subunit of the ApoB editing complex, raises the possibility that the function of Dnd1 is related to Apobec1 activity as a cytidine deaminase. We conducted a series of experiments with a genetically engineered deficiency of Apobec1 on the TGCT-susceptible 129/Sv inbred background to determine whether dosage of Apobec1 modifies susceptibility, either alone or in combination with Dnd1, and either in a conventional or a transgenerational manner. In the paternal germ-lineage, Apobec1 deficiency significantly increased susceptibility among heterozygous but not wild-type male offspring, without subsequent transgenerational effects, showing that increased TGCT risk resulting from partial loss of Apobec1 function is inherited in a conventional manner. By contrast, partial deficiency in the maternal germ-lineage led to suppression of TGCTs in both partially and fully deficient males and significantly reduced TGCT risk in a transgenerational manner among wild-type offspring. These heritable epigenetic changes persisted for multiple generations and were fully reversed after consecutive crosses through the alternative germ-lineage. These results suggest that Apobec1 plays a central role in controlling TGCT susceptibility in both a conventional and a transgenerational manner.
    Proceedings of the National Academy of Sciences 08/2012; 109(41):E2766-73. · 9.74 Impact Factor
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    ABSTRACT: BACKGROUND: Type 2 diabetes is associated with low-grade systemic inflammation, increasing the risk for various adverse health outcomes. PURPOSE: Our objective was to investigate the association between C-reactive protein (CRP), a marker for systemic inflammation, and lifestyle factors in a national sample of people with type 2 diabetes. METHODS: This study analyzed data from 1,086 men and women with diabetes, who completed the 1999-2004 NHANES. Lifestyle factors included diet quality, body mass index (BMI), smoking, and physical activity. RESULTS: Stratified logistic regression showed that for both men and women, BMI was a strong predictor of elevated CRP after adjusting for age, energy intake, race/ethnicity, medications, diabetes duration, and glycosylated hemoglobin. However, among men, but not among women, the likelihood of elevated CRP increased with lower diet quality and physical inactivity. CONCLUSIONS: Among people with type 2 diabetes, higher levels of CRP were associated with lower diet quality and physical inactivity among men, and with obesity among both men and women.
    Annals of Behavioral Medicine 08/2012; · 4.20 Impact Factor
  • Nada A Abumrad, Nicholas O Davidson
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    ABSTRACT: Intestinal lipid transport plays a central role in fat homeostasis. Here we review the pathways regulating intestinal absorption and delivery of dietary and biliary lipid substrates, principally long-chain fatty acid, cholesterol, and other sterols. We discuss the regulation and functions of CD36 in fatty acid absorption, NPC1L1 in cholesterol absorption, as well as other lipid transporters including FATP4 and SRB1. We discuss the pathways of intestinal sterol efflux via ABCG5/G8 and ABCA1 as well as the role of the small intestine in high-density lipoprotein (HDL) biogenesis and reverse cholesterol transport. We review the pathways and genetic regulation of chylomicron assembly, the role of dominant restriction points such as microsomal triglyceride transfer protein and apolipoprotein B, and the role of CD36, l-FABP, and other proteins in formation of the prechylomicron complex. We will summarize current concepts of regulated lipoprotein secretion (including HDL and chylomicron pathways) and include lessons learned from families with genetic mutations in dominant pathways (i.e., abetalipoproteinemia, chylomicron retention disease, and familial hypobetalipoproteinemia). Finally, we will provide an integrative view of intestinal lipid homeostasis through recent findings on the role of lipid flux and fatty acid signaling via diverse receptor pathways in regulating absorption and production of satiety factors.
    Physiological Reviews 07/2012; 92(3):1061-85. · 30.17 Impact Factor
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    ABSTRACT: Previous work demonstrated that intestinal cholesterol absorption and regulated expression of intestinal Niemann-Pick C1-like 1 and ATP-binding cassette protein A1 are required for liver X receptor (LXR) agonist-mediated increases in high-density lipoprotein biogenesis. We re-examined those conclusions in mice with intestine-specific deletion of the microsomal triglyceride transfer protein (MTTP-IKO), where chylomicron formation is eliminated. MTTP-IKO mice demonstrated sustained ≈90% reduction in cholesterol absorption and >80% reduction in Niemann-Pick C1-like 1 expression, yet LXR agonist treatment increased serum high-density lipoprotein and upregulated intestinal ATP-binding cassette protein A1 expression. Hepatic lipogenesis and triglyceride content increased with LXR agonist treatment in both genotypes. Biliary cholesterol secretion was increased in MTTP-IKO mice without further increase upon LXR agonist administration. LXR agonist treatment caused a paradoxical increase in cholesterol absorption in MTTP-IKO mice and decreased fecal neutral sterol excretion, but to levels that still exceeded fecal neutral sterol excretion in LXR agonist-treated control mice. Finally, MTTP-IKO mice demonstrated indistinguishable patterns of increased cholesterol turnover and efflux after intravenous radiolabeled cholesterol administration, with or without LXR agonist treatment. Both intestinal and hepatic cholesterol efflux pathways are basally upregulated in MTTP-IKO mice. Moreover, LXR-dependent pathways modulate intestinal cholesterol absorption, transport, efflux, and high-density lipoprotein production independent of chylomicron assembly and secretion.
    Arteriosclerosis Thrombosis and Vascular Biology 05/2012; 32(7):1624-31. · 6.34 Impact Factor
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    Nicholas O Davidson
    The Journal of Physiology 05/2012; 590(Pt 9):2067-8. · 4.38 Impact Factor
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    ABSTRACT: The intestinal mucus barrier prevents pathogen invasion and maintains host-microbiota homeostasis. We show that fatty acid synthase (FAS), an insulin-responsive enzyme essential for de novo lipogenesis, helps maintain the mucus barrier by regulating Mucin 2, the dominant mucin in the colon and a central component of mucus. Inducible Cre recombinase-directed inactivation of the FAS gene in the colonic epithelium of mice is associated with disruptions in the intestinal mucus barrier as well as increased intestinal permeability, colitis, systemic inflammation, and changes in gut microbial ecology. FAS deficiency blocked the generation of palmitoylated Mucin 2, which must be S-palmitoylated at its N terminus for proper secretion and function. Furthermore, a diabetic mouse model exhibited lower FAS levels and a decreased mucus layer, which could be restored with insulin treatment. Thus, the role of FAS in maintaining intestinal barrier function may explain the pathogenesis of intestinal inflammation in diabetes and other disorders.
    Cell host & microbe 02/2012; 11(2):140-52. · 13.02 Impact Factor
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    ABSTRACT: The tissue-specific sources and regulated production of physiological signals that modulate food intake are incompletely understood. Previous work showed that L-Fabp(-/-) mice are protected against obesity and hepatic steatosis induced by a high-fat diet, findings at odds with an apparent obesity phenotype in a distinct line of aged L-Fabp(-/-) mice. Here we show that the lean phenotype in L-Fabp(-/-) mice is recapitulated in aged, chow-fed mice and correlates with alterations in hepatic, but not intestinal, fatty acid amide metabolism. L-Fabp(-/-) mice exhibited short-term changes in feeding behavior with decreased food intake, which was associated with reduced abundance of key signaling fatty acid ethanolamides, including oleoylethanolamide (OEA, an agonist of PPARα) and anandamide (AEA, an agonist of cannabinoid receptors), in the liver. These reductions were associated with increased expression and activity of hepatic fatty acid amide hydrolase-1, the enzyme that degrades both OEA and AEA. Moreover, L-Fabp(-/-) mice demonstrated attenuated responses to OEA administration, which was completely reversed with an enhanced response after administration of a nonhydrolyzable OEA analog. These findings demonstrate a role for L-Fabp in attenuating obesity and hepatic steatosis, and they suggest that hepatic fatty acid amide metabolism is altered in L-Fabp(-/-) mice.
    The Journal of Lipid Research 02/2012; 53(4):744-54. · 4.39 Impact Factor

Publication Stats

4k Citations
1,518.08 Total Impact Points

Institutions

  • 2000–2014
    • Washington University in St. Louis
      • • Department of Medicine
      • • Division of Gastroenterology
      San Luis, Missouri, United States
  • 2013
    • Saint Louis University
      • School of Medicine
      Saint Louis, MI, United States
    • University of Texas Southwestern Medical Center
      • Department of Clinical Sciences
      Dallas, TX, United States
  • 2000–2012
    • University of Washington Seattle
      • • Department of Pediatrics
      • • Department of Medicine
      • • Division of Gastroenterology
      • • Division of General Internal Medicine
      Seattle, WA, United States
  • 2010
    • Brigham and Women's Hospital
      • Department of Medicine
      Boston, MA, United States
  • 1988–1999
    • University of Illinois at Chicago
      • Department of Medicine (Chicago)
      Chicago, Illinois, United States
  • 1988–1998
    • University of Chicago
      • • Department of Medicine
      • • Department of Pediatrics
      Chicago, IL, United States
  • 1996
    • University of Pennsylvania
      Philadelphia, Pennsylvania, United States
  • 1991
    • The University of Chicago Medical Center
      Chicago, Illinois, United States