A systems approach points to a therapeutic role for retinoids in asparaginase-associated pancreatitis.

Among drug-induced adverse events, pancreatitis is life-threatening and results in substantial morbidity. A prototype example is the pancreatitis caused by asparaginase, a crucial drug used to treat acute lymphoblastic leukemia (ALL). Here, we used a systems approach to identify the factors affecting asparaginase-associated pancreatitis (AAP). Connectivity Map analysis of the transcriptomic data showed that asparaginase-induced gene signatures were potentially reversed by retinoids (vitamin A and its analogs). Analysis of a large electronic health record database (TriNetX) and the U.S. Federal Drug Administration Adverse Events Reporting System demonstrated a reduction in AAP risk with concomitant exposure to vitamin A. Furthermore, we performed a global metabolomic screening of plasma samples from 24 individuals with ALL who developed pancreatitis (cases) and 26 individuals with ALL who did not develop pancreatitis (controls), before and after a single exposure to asparaginase. Screening from this discovery cohort revealed that plasma carotenoids were lower in the cases than in controls. This finding was validated in a larger external cohort. A 30-day dietary recall showed that the cases received less dietary vitamin A than the controls did. In mice, asparaginase administration alone was sufficient to reduce circulating and hepatic retinol. Based on these data, we propose that circulating retinoids protect against pancreatic inflammation and that asparaginase reduces circulating retinoids. Moreover, we show that AAP is more likely to develop with reduced dietary vitamin A intake. The systems approach taken for AAP provides an impetus to examine the role of dietary vitamin A supplementation in preventing or treating AAP.

Cyp1b1 directs Srebp-mediated cholesterol and retinoid synthesis in perinatal liver; Association with retinoic acid activity during fetal development.

BACKGROUND: Cytochrome P450 1b1 (Cyp1b1) deletion and dietary retinol deficiency during pregnancy (GVAD) affect perinatal liver functions regulated by Srebp. Cyp1b1 is not expressed in perinatal liver but appears in the E9.5 embryo, close to sites of retinoic acid (RA) signaling. HYPOTHESIS: Parallel effects of Cyp1b1 and retinol on postnatal Srebp derive from effects in the developing liver or systemic signaling. APPROACH: Cluster postnatal increases in hepatic genes in relation to effects of GVAD or Cyp1b1 deletion. Sort expression changes in relation to genes regulated by Srebp1 and Srebp2.Test these treatments on embryos at E9.5, examining changes at the site of liver initiation. Use in situ hybridization to resolve effects on mRNA distributions of Aldh1a2 and Cyp26a1 (RA homeostasis); Hoxb1 and Pax6 (RA targets). Assess mice lacking Lrat and Rbp4 (DKO mice) that severely limits retinol supply to embryos. RESULTS: At birth, GVAD and Cyp1b1 deletion stimulate gene markers of hepatic stellate cell (HSC) activation but also suppress Hamp. These treatments then selectively prevent the postnatal onset of genes that synthesize cholesterol (Hmgcr, Sqle) and fatty acids (Fasn, Scd1), but also direct cholesterol transport (Ldlr, Pcsk9, Stard4) and retinoid synthesis (Aldh1a1, Rdh11). Extensive support by Cyp1b1 is implicated, but with distinct GVAD interventions for Srebp1 and Srebp2. At E9.5, Cyp1b1 is expressed in the septum transversum mesenchyme (STM) with ß-carotene oxygenase (Bco1) that generates retinaldehyde. STM provides progenitors for the HSC and supports liver expansion. GVAD and Cyp1b1-/- do not affect RA-dependent Hoxb1 and Pax6. In DKO embryos, RA-dependent Cyp26a1 is lost but Hoxb1 is sustained with Cyp1b1 at multiple sites. CONCLUSION: Cyp1b1-/- suppresses genes supported by Srebp. GVAD effects distinguish Srebp1 and Srebp2 mediation. Srebp regulation overlaps appreciably in cholesterol and retinoid homeostasis. Bco1/Cyp1b1 partnership in the STM may contribute to this later liver regulation.

Vitamin A and ß-carotene in pregnant and breastfeeding post-bariatric women in an urban population.

Background As breastfeeding awareness and social acceptance are increased, maternal nutritional deficiency requires more investigation. Methods A prospective cohort study was conducted to determine if vitamin A deficiency is more common in pregnant, lactating post-bariatric surgery women in an inner city population. Antepartum, women after bariatric surgery and controls with no history of malabsorption were recruited. Third trimester, postpartum maternal blood and cord blood were collected as well as three breast milk samples: colostrum, transitional and mature milk. A nutritional survey of diet was completed. Each serum sample was analyzed for total retinol and ß-carotene; breast milk samples were analyzed for retinol and retinyl esters, total retinol and ß-carotene. Results Fifty-three women after bariatric surgery and 66 controls were recruited. Postpartum serum retinol was significantly higher in women after bariatric surgery in the univariate analysis (P<0.0001) and confirmed in the multiple linear mixed model (P=0.0001). Breast milk colostrum retinol and transitional milk total retinol were significantly greater in the bariatric surgery group in the univariate analysis (P=0.03 and P=0.02, respectively), but not after adjusting for confounders. Serum ß-carotene in the third trimester and postpartum were lower (P<0.0001 and P=0.003, respectively) in the bariatric surgery group but not after adjusting for confounders. Vitamin A deficiency was high in both groups in serum and breast milk samples. Conclusion Nutritional deficiencies in breastfeeding women after bariatric surgeries may in fact be less common than in control women in an inner city.

Alcohol exposure in utero perturbs retinoid homeostasis in adult rats.

BACKGROUND: Maternal alcohol exposure and adult alcohol intake have been shown to perturb the metabolism of various micro- and macro-nutrients, including vitamin A and its derivatives (retinoids). Therefore, it has been hypothesized that the well-known detrimental consequences of alcohol consumption may be due to deregulations of the metabolism of such nutrients rather than to a direct effect of alcohol. Alcohol exposure in utero also has long-term harmful consequences on the health of the offspring with mechanisms that have not been fully clarified. Disruption of tissue retinoid homeostasis has been linked not only to abnormal embryonic development, but also to various adult pathological conditions, including cancer, metabolic disorders and abnormal lung function. We hypothesized that prenatal alcohol exposure may permanently perturb tissue retinoid metabolism, predisposing the offspring to adult chronic diseases. METHODS: Serum and tissues (liver, lung and prostate from males; liver and lung from females) were collected from 60-75 day-old sprague dawley rats born from dams that were: (I) fed a liquid diet containing 6.7% alcohol between gestational day 7 and 21; or (II) pair-fed with isocaloric liquid diet during the same gestational window; or (III) fed ad libitum with regular rat chow diet throughout pregnancy. Serum and tissue retinoid levels were analyzed by reverse-phase high-performance liquid chromatography (HPLC). Serum retinol-binding protein (RBP) levels were measured by western blot analysis, and liver, lung and prostate mRNA levels of lecithin-retinol acyltransferase (LRAT) were measured by qPCR. RESULTS: Retinyl ester levels were significantly reduced in the lung of both males and females, as well as in the liver and ventral prostate of males born from alcohol-fed dams. Tissue LRAT mRNA levels remained unchanged upon maternal alcohol treatment. CONCLUSIONS: Prenatal alcohol exposure in rats affects retinoid metabolism in adult life, in a tissue- and sex-dependent manner. We propose that the alcohol-induced perturbations of vitamin A metabolism may predispose to detrimental consequnces on adult health.

High Preformed Vitamin A Intake during Pregnancy Prevents Embryonic Accumulation of Intact ß-Carotene from the Maternal Circulation in Mice.

BACKGROUND: The vitamin A precursor ß-carotene (BC) promotes mammalian embryonic development by serving as a source of retinoids (vitamin A derivatives) to the developing tissues. In the Western world, increased consumption of dietary supplements, including vitamin A and BC, is common; however, the consequences of maternal high preformed vitamin A intake on embryonic uptake and metabolism of BC are poorly understood. OBJECTIVE: This study investigated vitamin A and BC metabolism in developing mouse tissues after a single BC administration to pregnant wild-type (WT) mice fed purified diets with different vitamin A concentrations. METHODS: WT dams fed a sufficient vitamin A (VA-S; 4.2 µg of retinol/g of diet), high vitamin A (VA-H; 33 µg of retinol/g of diet), or excess vitamin A (VA-E; 66 µg of retinol/g of diet) diet throughout gestation were intraperitoneally injected with BC or vehicle at 13.5 d postcoitum (dpc). At 14.5 dpc, retinoid and BC concentrations in maternal serum and liver, placenta, and embryo were quantified by HPLC; expressions of genes controlling retinoid and BC homeostasis were analyzed by quantitative polymerase chain reaction. Maternal lipoprotein BC concentrations were analyzed by density gradient ultracentrifugation followed by HPLC. RESULTS: Intact BC was undetectable only in embryos from VA-E + BC dams. Relative to the VA-S + vehicle group, placentas from VA-S + BC dams showed 39% downregulation of LDL-receptor-related protein 1 (Lrp1 ); 35% downregulation of VLDL receptor (Vldlr); 56% reduced mRNA expression of ß-carotene 15,15'-oxygenase (Bco1); and 80% upregulation of ß-carotene 9',10'-oxygenase (Bco2). Placental cytochrome P450, family 26, subfamily A, polypeptide 1 (Cyp26A1) was upregulated 2-fold in the VA-E group compared with the VA-S group, regardless of maternal treatment. CONCLUSIONS: In mice, transfer of intact BC to the embryo is attenuated by high tissue vitamin A concentrations. Maternal vitamin A intake and BC availability activate a placental transcriptional response to protect the embryo from retinoid and carotenoid excess.

Insights into the molecular mechanisms of the anti-atherogenic actions of flavonoids in normal and obese mice.

Obesity is a major and independent risk factor for cardiovascular disease and it is strongly associated with the development of dyslipidemia, insulin resistance and type 2 diabetes. Flavonoids, a diverse group of polyphenol compounds of plant origin widely distributed in human diet, have been reported to have numerous health benefits, although the mechanisms underlying these effects have remained obscure. We analyzed the effects of chronic dietary supplementation with flavonoids extracted from cranberry (FLS) in normal and obese C57/BL6 mice compared to mice maintained on the same diets lacking FLS. Obese mice supplemented with flavonoids showed an amelioration of insulin resistance and plasma lipid profile, and a reduction of visceral fat mass. We provide evidence that the adiponectin-AMPK pathway is the main mediator of the improvement of these metabolic disorders. In contrast, the reduced plasma atherogenic cholesterol observed in normal mice under FLS seems to be due to a downregulation of the hepatic cholesterol synthesis pathway. Overall, we demonstrate for the first time that the molecular mechanisms underlying the beneficial effects of flavonoids are determined by the metabolic state.

Serum retinol-binding protein 4 (RBP4) and retinol in a cohort of borderline obese women with and without gestational diabetes.

OBJECTIVES: To evaluate whether serum RBP4 correlates with gestational diabetes mellitus (GDM) in a cohort of borderline obese (BMI>30) pregnant women. DESIGN AND METHODS: Serum RBP4 and retinol were measured in pregnant women with (n=12) and without (n=10) GDM. RESULTS: RBP4, retinol and RBP4:retinol molar ratio were not different between the groups and were not associated with markers of insulin resistance. CONCLUSIONS: GDM is not associated with RBP4 or retinol among borderline obese pregnant women.

Transcriptional activity of the murine retinol-binding protein gene is regulated by a multiprotein complex containing HMGA1, p54 nrb/NonO, protein-associated splicing factor (PSF) and steroidogenic factor 1 (SF1)/liver receptor homologue 1 (LRH-1).

Retinol-binding protein (RBP4) transports retinol in the circulation from hepatic stores to peripheral tissues. Since little is known regarding the regulation of this gene, we analysed the cis-regulatory sequences of the mouse RBP4 gene. Our data show that transcription of the gene is regulated through a bipartite promoter: a proximal region necessary for basal expression and a distal segment responsible for cAMP-induction. This latter region contains several binding sites for the structural HMGA1 proteins, which are important to promoter regulation. We further demonstrate that HMGA1s play a key role in basal and cAMP-induction of Rbp4 transcription and the RBP4 and HMGA1 genes are coordinately regulated in vitro and in vivo. HMGA1 acts to recruit transcription factors to the RBP4 promoter and we specifically identified p54(nrb)/NonO and protein-associated splicing factor (PSF) as components that interact with this complex. Steroidogenic factor 1 (SF1) or the related liver receptor homologue 1 (LRH-1) are also associated with this complex upon cAMP-induction. Depletion of SF1/LRH-1 by RNA interference resulted in a dramatic loss of cAMP-induction. Collectively, our results demonstrate that basal and cAMP-induced Rbp4 transcription is regulated by a multiprotein complex that is similar to ones that modulate expression of genes of steroid hormone biosynthesis. Since genes related to glucose metabolism are regulated in a similar fashion, this suggests that Rbp4 expression may be regulated as part of a network of pathways relevant to the onset of type 2 diabetes.

The intersection between the aryl hydrocarbon receptor (AhR)- and retinoic acid-signaling pathways.

Data from a variety of animal and cell culture model systems have demonstrated an interaction between the aryl hydrocarbon receptor (AhR)- and retinoic acid (RA)-signaling pathways. The AhR(1) was originally identified as the receptor for the polycyclic aromatic hydrocarbon family of environmental contaminants; however, recent data indicate that the AhR binds to a variety of endogenous and exogenous compounds, including some synthetic retinoids. In addition, activation of the AhR pathway alters the function of nuclear hormone-signaling pathways, including the estrogen, thyroid, and RA pathways. Activation of the AhR pathway through exposure to environmental compounds results in significant changes in RA synthesis, catabolism, transport, and excretion. Some effects on retinoid homeostasis mediated by the AhR pathway may result from the interactions of these two pathways at the level of activating or repressing the expression of specific genes. This chapter will review these two pathways, the evidence demonstrating a link between them, and the data indicating the molecular basis of the interactions between these two pathways.

Effect of vitamin A depletion on nonvisual phototransduction pathways in cryptochromeless mice.

Mice exhibit multiple nonvisual responses to light, including 1) photoentrainment of circadian rhythm; 2) "masking," which refers to the acute effect of light on behavior, either negative (activity suppressing) or positive (activity inducing); and 3) pupillary constriction. In mammals, the eye is the sole photosensory organ for these responses, and it contains only 2 known classes of pigments: opsins and cryptochromes. No individual opsin or cryptochrome gene is essential for circadian photoreception, gene photoinduction, or masking. Previously, the authors found that mice lacking retinol-binding protein, in which dietary depletion of ocular retinaldehyde can be achieved, had normal light signaling to the SCN, as determined by per gene photoinduction. In the present study, the authors analyzed phototransduction to the SCN in vitamin A-replete and vitamin A-depleted rbp-/- and rbp-/-cry1-/-cry2-/- mice using molecular and behavioral end points. They found that vitamin A-depleted rbp-/- mice exhibit either normal photoentrainment or become diurnal. In contrast, while vitamin A-replete rbp-/-cry1-/-cry2-/- mice are light responsive (with reduced sensitivity), vitamin A-depleted rbp-/-cry1-/-cry2-/- mice, which presumably lack functional opsins and cryptochromes, lose most behavioral and molecular responses to light. These data demonstrate that both cryptochromes and opsins regulate nonvisual photoresponses.