Serum Retinoid Research Articles

Reduced plasma carotenoids in individuals suffering from metabolic diseases with disturbances in lipid metabolism: a systematic review and meta-analysis of observational studies

This review summarises the association between serum carotenoids, serum retinoids and dietary intake outcomes with obesity/overweight and individuals with metabolic diseases with disturbances in lipid metabolism. Observational studies reporting dietary intakes and serum concentrations of carotenoids and retinol were collected from Medline and Web of Science. Mean differences were calculated between “cases” (classified as obese, overweight or having a metabolic disease with disturbances in lipid metabolism; i.e. non-alcoholic fatty liver disease, type 2 diabetes, dyslipidaemia or metabolic syndrome) and “comparator group” (classified as normal weight healthy individuals) and summarised in meta-analyses. Significant summary measures were observed for most serum provitamin A and non-provitamin A carotenoids. Studies reporting total serum carotenoids had shown the greatest decrease (–0.28 µmol/l [–0.33, −0.23], p<.001, I 2=62.5%, n = 7). There were no significant summary measures for dietary outcomes, suggesting a physiological role of low serum carotenoids in the development of obesity and associated diseases.

Association of Serum Carotenoids and Retinoids with Intraprostatic Inflammation in Men without Prostate Cancer or Clinical Indication for Biopsy in the Placebo Arm of the Prostate Cancer Prevention Trial

Non-supplemental carotenoids and retinol may potentiate antioxidant and anti-inflammatory mechanisms. Chronic intraprostatic inflammation is linked to prostate carcinogenesis. We investigated the association of circulating carotenoids and retinol with intraprostatic inflammation in benign tissue. We included 235 men from the Prostate Cancer Prevention Trial placebo arm who had a negative end-of-study biopsy, most (92.8%) done without clinical indication. α-carotene, β-carotene, β-cryptoxanthin, lycopene, and retinol were assessed by high-performance liquid chromatography using pooled year 1 and 4 serum. Presence and extent of intraprostatic inflammation in benign tissue was assessed in 3 (of 6–10) biopsy cores. Logistic (any core with inflammation vs none) and polytomous logistic (some or all cores with inflammation vs none) regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) of intraprostatic inflammation by concentration tertile adjusting for age, race, prostate cancer family history, and serum cholesterol. None of the carotenoids or retinol was associated with intraprostatic inflammation, except β-cryptoxanthin, which appeared to be positively associated with any core with inflammation [vs none, T2: OR (95% CI) = 2.67 (1.19, 5.99); T3: 1.80 (0.84, 3.82), P-trend = 0.12]. These findings suggest that common circulating carotenoids and retinol are not useful dietary intervention targets for preventing prostate cancer via modulating intraprostatic inflammation.

Retinoid and carotenoid status in serum and liver among patients at high-risk for liver cancer.

BackgroundApproximately 2.7 million Americans are chronically infected with hepatitis C virus (HCV). HCV patients with cirrhosis form the largest group of persons at high risk for hepatocellular carcinoma (HCC). Increased oxidative stress is regarded as a major mechanism of HCV-related liver disease progression. Deficiencies in retinoid and carotenoid antioxidants may represent a major modifiable risk factor for disease progression. This study aims to identify key predictors of serum antioxidant levels in patients with HCV, to examine the relationship between retinoid/carotenoid concentrations in serum and hepatic tissue, to quantify the association between systemic measures of oxidative stress and antioxidant status, and to examine the relationship between retinoids and stellate cell activation.MethodsPatients undergoing liver biopsy (n = 69) provided fasting blood, fresh tissue, urine and completed a diet history questionnaire. Serum and questionnaire data from healthy volunteers (n = 11), normal liver tissue from public repositories and patients without liver disease (n = 11) were also collected. Urinary isoprostanes, serum and tissue retinoid concentrations were obtained by UHPLC-MS-MS. Immunohistochemistry for αSMA was performed on FFPE sections and subsequently quantified via digital image analysis. Associations between urinary isoprostanes, αSMA levels, and retinoids were assessed using Spearman correlation coefficients and non-parametric tests were utilized to test differences among disease severity groups.ResultsThere was a significant inverse association between serum retinol, lycopene, and RBP4 concentrations with fibrosis stage. Serum β-carotene and lycopene were strongly associated with their respective tissue concentrations. There was a weak downward trend of tissue retinyl palmitate with increasing fibrosis stage. Tissue retinyl palmitate was inversely and significantly correlated with hepatic αSMA expression, a marker for hepatic stellate cell activation (r = −0.31, P < 0.02). Urinary isoprostanes levels were inversely correlated with serum retinol, β-carotene, and RBP4.ConclusionsA decrease in serum retinol, β-carotene, and RBP4 is associated with early stage HCV. Retinoid and carotenoid levels decline as disease progresses, and our data suggest that this decline occurs early in the disease process, even before fibrosis is apparent. Measures of oxidative stress are associated with fibrosis stage and concurrent antioxidant depletion. Vitamin A loss is accompanied by stellate cell activation in hepatic tissue.Electronic supplementary materialThe online version of this article (doi:10.1186/s12876-016-0432-5) contains supplementary material, which is available to authorized users.

Abstract 2821: Joint relationship between iron and retinoids in patients at high-risk for liver cancer

Abstract Approximately 3.2 million Americans are chronically infected with Hepatitis C, forming the largest group of persons at high risk for HCC, with an annual incidence of 3-4%. Increased oxidative stress is regarded as the major mechanism of progression in chronic liver disease (CLD) and subsequent HCC. Hepatic iron overload facilitates the production of reactive oxygen species (ROS), thereby inducing liver damage and fibrosis. We have previously shown that retinoid and carotenoid depletion occurs early in disease and may represent a major modifiable risk. This study aims to determine, in CLD patients and controls, whether retinoid levels modify the association between serum iron concentrations and: (a) oxidative stress biomarkers in urine (b) tissue changes associated with hepatic stellate cell (HSC) activation, and (c) CLD progression. Patients with HCV undergoing liver biopsy (n = 69) provided fasting blood, fresh tissue, urine and completed a diet history questionnaire (DHQ). Serum and questionnaire data from healthy volunteers (n = 11), normal liver tissue from public repositories and patients without liver disease (n = 11) were also collected. Urinary isoprostanes, serum and tissue retinoid concentrations were obtained by LC-MS-MS. Serum iron, ferritin and transferrin were quantitated. Immunohistochemistry for αSMA was performed on FFPE sections and subsequently quantified via digital image analysis. Associations between urinary isoprostanes, αSMA levels, serum iron, serum and tissue retinoids were assessed using Spearman correlation coefficients and non-parametric tests were utilized to test differences among disease severity groups. There was a significant increasing trend for serum transferrin levels with progressive fibrosis, but not for serum iron and ferritin concentrations. All subjects had transferrin saturation within the normal range. Serum β-carotene and lycopene were inversely associated with serum ferritin concentrations (r = -0.29, P &amp;lt; 0.01; r = -0.29, P &amp;lt; 0.01) however, this relationship was not observed for other serum iron measurements. Serum iron measurements were not associated with hepatic retinoids/carotenoids, αSMA expression or urinary isoprostanes. Tissue retinyl palmitate was inversely and significantly correlated with hepatic αSMA expression (r = -0.3, P &amp;lt; 0.02). Serum iron overload was not evident in this population even though a depletion of serum retinoids/carotenoids is observed. The inverse correlation observed between serum ferritin and retinoids/carotenoids suggests a possible joint effect in CLD patients. Our data provide confirmation that hepatic retinoid loss is accompanied by HSC activation, a key player in fibrosis. Further evaluation of hepatic iron status is warranted to assess the relationships between iron and retinoids in HCV. Citation Format: Yachana Kataria, Ryan Deaton, Erika Enk, Milita Petrauskaite, Scott Cotler, Donald Jensen, Peter Gann. Joint relationship between iron and retinoids in patients at high-risk for liver cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2821. doi:10.1158/1538-7445.AM2015-2821

Alcohol exposure in utero perturbs retinoid homeostasis in adult rats.

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. 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. 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. 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.

Abstract 2144: Retinoid and carotenoid depletion in patients at high-risk for liver cancer

Abstract Approximately 3.2 million Americans are chronically infected with hepatitis C (HCV), forming the largest group at high-risk for hepatocellular carcinoma (HCC). Oxidative stress due to chronic inflammation impels the progression of chronic liver disease (CLD) &amp; subsequent HCC. Deficiencies in dietary antioxidants such as retinoids and carotenoids may represent a modifiable risk factor for HCC progression. This study aims to identify key predictors of serum antioxidant levels in patients with CLD, to quantify the association between systemic measures of oxidative stress and antioxidant status, and to examine the relationship between retinoid/carotenoid concentrations in serum and hepatic tissue. Patients with HCV undergoing liver biopsy (n=69) provided fasting blood, fresh tissue, urine, and responses to a diet history questionnaire (DHQ). We also collected serum and questionnaire data from healthy volunteers (n=11), and normal liver tissue from public repositories and patients without liver disease (n=11). Serum and tissue retinoid concentrations were obtained by mass spectroscopy. Serum retinol binding protein 4 (RBP4) was quantified by ELISA. Urine 8OHdG and F2α-isoprostanes were determined by mass spectroscopy. Dietary retinoid intake was estimated by DHQ. Associations between diet, serum and tissue retinoids, and urinary oxidative stress markers were assessed by Spearman correlation coefficients. Dietary β-carotene and lutein were associated with their respective serum concentrations (r = 0.24, p = 0.05; r = 0.33, p &amp;lt; 0.01). There was a significant downward trend for serum retinol, lycopene and RBP4 concentrations with progressive fibrosis; mean serum concentrations were lower in subjects with chronic HCV but no fibrosis compared to controls. Urinary isoprostanes levels were inversely correlated with serum retinol (r= -0.22, p = 0.05), β-carotene (r= -0.22 p = 0.05), and RBP4 (r= -0.25 p = 0.03). Urinary 8OHDG did not correlate with any serum retinoids or carotenoids. Serum β-carotene and lycopene were strongly associated with the respective tissue concentrations (r = 0.56, p&amp;lt;.01; r= 0.76 p&amp;lt; 0.01); however, serum retinol and tissue retinyl palmitate did not correlate in this population (r = -0.08 p = 0.55). There was a suggestive downward trend of tissue retinyl palmitate with increasing levels of fibrosis. Depletion of serum retinol, β-carotene, and RBP4 worsens with liver fibrosis severity. RBP4 might be a better marker for vitamin A status due to its stronger association with disease severity. Retinoid and carotenoid levels decline as disease progresses, and our data suggest that this decline occurs early in the disease process, even before fibrosis is apparent. In HCV patients, decreases in retinoid/carotenoid levels are accompanied by an increase in urinary F2α-isoprostanes, an indicator of lipid peroxidation due to oxidative stress. Dietary or chemopreventive strategies for replenishing antioxidant levels should be studied further. Citation Format: Yachana Kataria, Erika Enk Rueter, Ryan Deaton, Donald Jensen, Scott Cotler, Peter Gann. Retinoid and carotenoid depletion in patients at high-risk for liver cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2144. doi:10.1158/1538-7445.AM2014-2144

Hypervitaminosis A is prevalent in children with CKD and contributes to hypercalcemia.

BackgroundVitamin A accumulates in renal failure, but the prevalence of hypervitaminosis A in children with predialysis chronic kidney disease (CKD) is not known. Hypervitaminosis A has been associated with hypercalcemia. In this study we compared dietary vitamin A intake with serum retinoid levels and their associations with hypercalcemia.MethodsWe studied the relationship between vitamin A intake, serum retinoid levels, and serum calcium in 105 children with CKD stages 2–5 on dialysis and posttransplant. Serum retinoid measures included retinol (ROH), its active retinoic acid (RA) metabolites [all-trans RA (at-RA) and 13-cis RA] and carrier proteins [retinol-binding protein-4 (RBP4) and transthyretin (TTR)]. Dietary vitamin A intake was assessed using a food diary.ResultsTwenty-five children were in CKD 2–3, 35 in CKD 4–5, 23 on dialysis and 22 posttransplant; 53 % had vitamin A intake above the Reference Nutrient Intake (RNI) value. Children receiving supplemental feeds compared with diet alone had higher vitamin A intake (p = 0.02) and higher serum ROH (p < 0.001). Notably, increased ROH was seen as early as CKD stage 2. For every 10 ml/min/1.73 m2 fall in estimated glomerular filtration rate (eGFR), there was a 13 % increase in ROH. RBP4 levels were increased in CKD 3–5 and dialysis patients. The lowest ratios of ROH:RBP4 were seen in dialysis compared with CKD 2–3 (p = 0.03), suggesting a relative increase in circulating RBP4. Serum ROH, RBP4 and at-RA were associated with serum calcium. On multivariable analysis RBP4 levels and alfacalcidol dose were significant predictors of serum calcium (model R 2 32 %) in dialysis patients.ConclusionsHypervitaminosis A is seen in early CKD, with highest levels in children on supplemental feeds compared with diet alone. Serum retinoid levels significantly predict hypercalcemia.

Effects of diet and strain on mouse serum and tissue retinoid concentrations.

The relationship between dietary vitamin A and all-trans-retinoic acid levels in serum and tissues had not been quantified. We determined the impact of dietary vitamin A on retinoid levels in serum, liver, kidney, testis, and epididymal white adipose of five mouse strains: AKR/J; BALB/cByJ; C3H/HeJ; C57BL/6J; 129S1/SvImJ. Retinoids were quantified in mice fed copious vitamin A (lab chow, ≥20 IU/g) followed by one month feeding a vitamin A-sufficient diet (4 IU/g), or after three generations of feeding a vitamin A-sufficient diet. Retinol and retinyl esters were measured by high-performance liquid chromatography with ultraviolet absorbance detection. All-trans-retinoic acid was quantified by liquid chromatography tandem mass spectrometry. The amounts of dietary vitamin A had long-term strain-specific effects on tissue retinyl ester, retinol and all-trans-retinoic acid concentrations. Three generations of feeding a vitamin A-sufficient diet decreased all-trans-retinoic acid in most tissues of most strains, in some cases more than 60%, compared to a diet with copious vitamin A. With both diets, all-trans-retinoic acid concentrations maintained an order of liver ≈ testis > kidney > white adipose tissue ≈ serum. Neither retinol nor all-trans-retinoic acid in serum reflected all-trans-retinoic acid concentrations in tissues. Strain and tissue-specific differences in retinol and all-trans-retinoic acid altered by different amounts of dietary vitamin A could have profound effects on retinoid action. This would be the case especially with the increased all-trans-retinoic acid values associated with the amounts of vitamin A and its precursors (carotenoids) in chow diets.

Gestational and lactational exposure to the polychlorinated biphenyl mixture Aroclor 1254 modulates retinoid homeostasis in rat offspring

Polychlorinated biphenyls (PCBs) induce a broad spectrum of biochemical and toxic effects in mammals including alterations of the vital retinoid (vitamin A) system. The aim of this study was to characterize alterations of tissue retinoid levels in rat offspring and their dams following gestational and lactational exposure to the PCB mixture Aroclor 1254 (A1254) and to assess the interrelationship of these changes with other established sensitive biochemical and toxicological endpoints. Sprague-Dawley rat dams were exposed orally to 0 or 15mg/kg body weight/day of A1254 from gestational day 1 to postnatal day (PND) 23. Livers, kidneys and serum were collected from the offspring on PNDs 35, 77 and 350. Tissue and serum retinoid levels, hepatic cytochrome P450 (CYP) enzymes and serum thyroid hormones were analyzed. A multivariate regression between A1254 treatment, hepatic retinoid levels, hepatic CYP enzymes activities, thyroid hormone levels and body/liver weights was performed using an orthogonal partial least-squares (PLS) analysis. The contribution of dioxin-like (DL) components of A1254 to the observed effects was also estimated using the toxic equivalency (TEQ) concept. In both male and female offspring short-term alterations in tissue retinoid levels occurred at PND35, i.e. decreased levels of hepatic retinol and retinoic acid (RA) metabolite 9-cis-4-oxo-13,14-dihydro-RA with concurrent increases in hepatic and renal all-trans-RA levels. Long-term changes consisted of decreased hepatic retinyl palmitate and increased renal retinol levels that were apparent until PND350. Retinoid system alterations were associated with altered CYP enzyme activities and serum thyroid hormone levels as well as body and liver weights in both offspring and dams. The estimated DL activity was within an order of magnitude of the theoretical TEQ for different endpoints, indicating significant involvement of DL congeners in the observed effects. This study shows that tissue retinoid levels are affected both short- and long-term by developmental A1254 exposure and are associated with alterations of other established endpoints of toxicological concern.

Increased uptake of dietary retinoids at the maternal-fetal barrier in the nitrofen model of congenital diaphragmatic hernia

Background/PurposeThe retinol signaling pathway is disrupted in congenital diaphragmatic hernia (CDH). Since there is no fetal retinol synthesis, maternal retinol has to cross the placenta. Nitrofen interferes with the retinol-binding protein (RBP) transfer pathway in CDH. However, in RBP knockout mice, retinol has been shown to be present. In this model, increased uptake of maternal dietary retinyl ester (RE) bounded in low-dense-lipoprotein (LDL) through low-density-lipoprotein-receptor 1 (LRP1) and increased activity of RE hydrolysis by lipoprotein-lipase (LPL) have been found. The aim of this study was to investigate the RE transfer pathway in the nitrofen CDH model. MethodsPregnant rats were treated with nitrofen or vehicle on gestational day (D9) and sacrificed on D21. Immunohistochemistry was performed to evaluate LRP1 and LPL protein expression. Serum LDL levels were measured by ELISA. Pulmonary and serum retinoid levels were measured using HPLC. ResultsMarkedly increased trophoblastic and pulmonary LRP1 and LPL immunoreactivity were observed in CDH compared to controls. Significantly increased serum LDL and RE levels were observed in CDH compared to controls. ConclusionsThe increased uptake of dietary retinoids at the maternal-fetal barrier in the nitrofen CDH model suggests that the RE transfer pathway may be the main source of retinol in this model.

The Retinoic Acid-Metabolizing Enzyme Cyp26b1 Regulates CD4 T Cell Differentiation and Function

The vitamin A metabolite retinoic acid (RA) has potent immunomodulatory properties that affect T cell differentiation, migration and function. However, the precise role of RA metabolism in T cells remains unclear. Catabolism of RA is mediated by the Cyp26 family of cytochrome P450 oxidases. We examined the role of Cyp26b1, the T cell-specific family member, in CD4+ T cells. Mice with a conditional knockout of Cyp26b1 in T cells (Cyp26b1 −/− mice) displayed normal lymphoid development but showed an increased sensitivity to serum retinoids, which led to increased differentiation under both inducible regulatory T (iTreg) cell- and TH17 cell-polarizing conditions in vitro. Further, Cyp26b1 expression was differentially regulated in iTreg and TH17 cells. Transfer of naïve Cyp26b1 −/− CD4+ T cells into Rag1 −/− mice resulted in significantly reduced disease in a model of T cell-dependent colitis. Our results show that T cell-specific expression of Cyp26b1 is required for the development of T cell-mediated colitis and may be applicable to the development of therapeutics that target Cyp26b1 for the treatment of inflammatory bowel disease.

Investigating piglet kidney vitamin A concentrations after high dose supplementation at birth

Potential metabolism and toxicity issues with infant vitamin A dosing procedures have led to a vested interest by the World Health Organization. Whole body retinoid trafficking was under investigation by determination of serum, liver, lung, kidney, adrenal, and spleen retinoid concentrations of piglets born from vitamin A depleted sows and dosed at birth with 25K, 50K, or 200K IU preformed vitamin A. These doses represent levels currently administered to newborn children and mothers in regions with high prevalence of vitamin A deficiency. Retinoids are known to be stored in these tissues with kidney being the primary extrahepatic storage site. In this study, kidneys were analyzed by grinding with sodium sulfate and adding C‐23 alcohol as an internal standard. Dichloromethane was used to extract retinol and retinyl esters. All samples were saponified, extracted, and injected onto an HPLC system to analyze total retinol content. A subgroup was also analyzed unsaponified to elucidate the retinyl ester profile. Data will be used collectively with other organ and serum data to have a complete model for vitamin A circulation and storage under a deficient status followed by high dose paradigm.Grant Funding Source: World Health Organization

A sensitive and specific method for measurement of multiple retinoids in human serum with UHPLC-MS/MS

Retinol (vitamin A) circulates at 1-4 μM concentration and is easily measured in serum. However, retinol is biologically inactive. Its metabolite, retinoic acid (RA), is believed to be responsible for biological effects of vitamin A, and hence the measurement of retinol concentrations is of limited value. A UHPLC-MS/MS method using isotope-labeled internal standards was developed and validated for quantitative analysis of endogenous RA isomers and metabolites. The method was used to measure retinoids in serum samples from 20 healthy men. In the fed state, the measured concentrations were 3.1 ± 0.2 nM for atRA, 0.1 ± 0.02 nM for 9-cisRA, 5.3 ± 1.3 nM for 13-cisRA, 0.4 ± 0.4 nM for 9,13-dicisRA, and 17.2 ± 6.8 nM for 4oxo-13-cisRA. The concentrations of the retinoids were not significantly different when measured after an overnight fast (3.0 ± 0.1 nM for atRA, 0.09 ± 0.01 nM for 9-cisRA, 3.9 ± 0.2 nM for 13-cisRA, 0.3 ± 0.1 nM for 9,13-dicisRA, and 11.9 ± 1.6 nM for 4oxo-13-cisRA). 11-cisRA and 4OH-RA were not detected in human serum. The high sensitivity of the MS/MS method combined with the UHPLC separation power allowed detection of endogenous 9-cisRA and 4oxo-atRA for the first time in human serum.

Combination antiretroviral therapy and chronic HIV infection affect serum retinoid concentrations: longitudinal and cross-sectional assessments

BackgroundSeveral lines of evidence suggest that retinoids (retinol-ROL or vitamin A, and its active metabolites, retinoic acids-RAs) play important pathogenic roles in HIV infection and combination antiretroviral therapy (cART)-related events. We previously reported that antiretrovirals alter RAs synthesis in vitro. We hypothesised that in vivo serum retinoid concentrations are affected by both cART and HIV infection. This might explain several clinical and laboratory abnormalities reported in HIV-infected patients receiving cART.MethodsThe effects of optimal cART and chronic HIV on serum retinoids were firstly assessed longitudinally in 10 HIV-infected adults (group1 = G1): twice while on optimal cART (first, during long-term and second, during short term cART) and twice during 2 cART interruptions when HIV viral load (VL) was detectable. Retinoid concentrations during optimal long term cART in G1 were compared with cross-sectional results from 12 patients (G2) with suboptimal cART (detectable VL) and from 28 healthy adults (G3). Serum retinoids were measured by HPLC with ultraviolet detection. Retinoid concentrations were correlated with VL, CD4+ T- cell count and percentages, CD8+38+ fluorescence, triglycerides, cholesterol and C-peptide serum levels.ResultsDuring optimal cART, G1 participants had drastically reduced RAs (0.5 ± 0.3 μg/dL; P < 0.01) but the highest ROL (82 ± 3.0 μg/dL) concentrations. During cART interruptions in these patients, RAs slightly increased whereas ROL levels diminished significantly (P < 0.05). G3 had the highest RAs levels (7.2 ± 1.1 μg/dL) and serum ROL comparable to values in North Americans. Serum ROL was decreased in G2 (37.7 ± 3.2 μg/dL; P < 0.01). No correlations were noted between RA and ROL levels or between retinoid concentrations and CD4+ T- cell count, CD8+38+ fluorescence, VL. ROL correlated with triglycerides and cholesterol in G1 (rs = 0.8; P = 0.01).ConclusionsSerum RAs levels are significantly diminished by cART, whereas ROL concentrations significantly decreased during uncontrolled HIV infection but augmented with optimal cART. These alterations in retinoid concentrations may affect the expression of retinoid-responsive genes involved in metabolic, hormonal and immune processes and be responsible for some adverse events observed in HIV-infected persons treated with antiretrovirals. Further studies should assess concomitant serum and intracellular retinoid levels in different clinical situations in larger, homogenous populations.

The role of β‐carotene and its cleavage enzyme β‐carotene‐ 15,15′‐oxygenase (CMO1) during mammalian embryonic development

The mammalian developing fetus relies on maternal circulating retinoids (vitamin A and its derivatives) to support its elevated vitamin A requirements. Β‐carotene is the major precursor of vitamin A in the human diet, and the central cleavage enzyme, β‐ carotene‐15,15′‐oxygenase (CMO1) has been suggested as the main enzyme involved in the production of vitamin A from β‐ carotene in vivo. To study the role of β‐carotene as vitamin A precursor during development we performed loss of CMO1 function studies in mice lacking retinol‐binding protein (RBP), an established model of embryonic vitamin A deficiency. Embryos from dams lacking both CMO1 and RBP (CMO1−/−RBP−/−) bred on a vitamin A‐deficient diet were malformed, but their defects were more severe than those of RBP−/ − mice. Since no differences were observed in serum retinoids levels between CMO1−/ −RBP−/ − and RBP−/ − dams, the embryonic malformations were likely due to the lack of CMO1 in the developing tissues. Upon maternal administration of β‐carotene, defects were almost fully rescued in CMO1+/−RBP−/ − embryos, while only partially improved in CMO1−/ −RBP−/ − embryos. These data suggest that CMO1 is a key enzyme in the conversion of β‐carotene to vitamin A in the developing tissues. However, they do not rule out a contribution of the β‐carotene asymmetric cleavage enzyme, β‐carotene‐9,10′‐ oxygenase (CMO2), to this process.Grant Funding Source: NIH 5R01HD57493

β-Carotene promotes the development of NNK-induced small airway-derived lung adenocarcinoma

Aimβ-Carotene has shown cancer-preventive effects in preclinical studies while increasing lung cancer mortality in clinical trials. We have shown that β-carotene stimulates cAMP signalling in vitro. Here, we have tested the hypothesis that β-carotene promotes the development of pulmonary adenocarcinoma (PAC) in vivo via cAMP signalling. MethodsPAC was induced in hamsters with the carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), followed by β-carotene for 1.5 years. Incidence, multiplicity and size of lung tumours were recorded, and phosphorylated CREB and ERK1/2 in tumour cells were determined by Western blots. Cyclic AMP in blood cells was analysed by immunoassays, retinoids in serum and lungs by HPLC. Resultsβ-Carotene increased lung tumour multiplicity, lung tumour size, blood cell cAMP, serum and lung levels of retinoids and induced p-CREB and p-ERK1/2 in lung tumours. ConclusionsOur data suggest that β-carotene promotes the development of PAC via increased cAMP signalling.

Serum retinoic acid, retinol and retinyl palmitate levels in patients with lung cancer

Epidemiological studies have shown an inverse relationship between dietary vitamin A intake and the risk of developing lung cancer. The aim of this study was to investigate the vitamin A status in patients with lung cancer, by determining the serum levels of retinoic acid, retinol and retinyl palmitate. In total, 36 patients with lung cancer and 27 controls were assessed. Of the patients 14 had squamous cell carcinoma, 3 adenocarcinoma, 15 non-small cell lung cancer and 4 small cell lung cancer. Serum retinoic acid, retinol and retinyl palmitate levels were determined with HPLC and UV detection, after liquid extraction. Serum retinol levels did not differ between patients (733.5 +/- 326.4 ng/mL) and controls (734.5 +/- 337.1 ng/mL). The retinyl palmitate concentration tended to be lower in patients (14.3 +/- 9.7 ng/mL) than in controls (16.7 +/- 13.7 ng/mL). The serum retinoic acid levels were significantly lower in patients (1.9 +/- 0.6 ng/mL) than in controls (2.5 +/- 1.1 ng/mL, P < 0.05). A positive correlation was observed between the retinol and retinoic acid levels and retinyl palmitate and retinoic acid levels. The lower levels of retinoic acid in patients with lung cancer suggest there may be a deficiency or impairment in retinol metabolism in these patients. Further studies with larger numbers of patients are needed to evaluate the possible relationship between serum retinoid levels and lung cancer.

Serum Retinoids and β-Carotene as Predictors of Hip and Other Fractures in Elderly Women

There is debate about the possible deleterious effect of excessive vitamin A exposure on fracture risk. In this nested case control study in older women (312 cases and 934 controls), serum retinol, retinyl palmitate, and beta-carotene were not associated with fracture risk, and there was no evidence of excess risk with multivitamin or cod liver oil supplementation. Recent studies have suggested that higher vitamin A intake may account for a component of fracture risk within the general population and that supplemental vitamin A may be harmful even within recommended limits. No studies have examined the relationship between biochemical retinol status and fracture in older women. We examined serum retinol, retinyl palmitate, and beta-carotene as predictors of incident hip and other fractures in a large prospective study of British women over the age of 75 years (n = 2606, 312 incident osteoporotic fractures, 92 incident hip fractures; mean follow-up duration, 3.7 years). Fasting blood samples (9:00-11:00 a.m.) were collected at baseline. Using a case-control design (three controls per case), serum retinol, retinyl palmitate, and beta-carotene were assessed as univariate predictors of incident osteoporotic fracture or hip fracture. Baseline BMD at the total hip, age, 25(OH)D, serum beta Crosslaps, bone-specific alkaline phosphatase, weight, height, and smoking were considered as covariates in a multivariate model. Serum retinol, retinyl palmitate, and beta-carotene were not significant univariate predictors of either hip fracture or any fracture (all p > 0.05; Cox proportional hazards regression). For all osteoporotic fractures, the hazard ratio (HR) was 0.92 (95% CI, 0.81-1.05) per 1 SD increase in serum retinol. Risk of any osteoporotic fracture was slightly less in the highest quartile of serum retinol compared with the lowest quartile (HR, 0.85; 95% CI, 0.69-1.05; p = 0.132) There was a tendency for increased serum retinol to predict benefit rather than harm in terms of BMD (r = 0.09, p = 0.002). Multivitamin or cod liver oil supplementation was associated with a significantly lower risk of any fracture (HR, 0.76; 95% CI, 0.60-0.96; p = 0.021). In multivariate analysis, only age, total hip BMD, and weight were associated with fracture risk (p < 0.05). We found no evidence to support any skeletal harm associated with increased serum indices of retinol exposure or modest retinol supplementation in this population.

Phase I/II trial of interferon α2b and ATRA-IV in the treatment of patients with advanced renal cancer

4606 Background: We previously reported the safety of combining IFN α2b (IFN) with low dose (15 mg/m2 TIW) liposome-encapsulated all-trans retinoic acid (ATRA-IV) in patients (pts) with renal cancer (RC) (Cancer 2002;95:1220). ATRA-IV possesses increased and prolonged serum retinoid levels compared to oral ATRA. We conducted a phase I/II trial of higher-dose weekly ATRA-IV in combination with IFN in pts with advanced RC. Methods: Pts had histologically confirmed advanced RC, measurable disease and a KPS of ≥60%. In the phase I study, cohorts of 3–6 pts were treated with weekly ATRA-IV (dose levels: 60, 75, and 90 mg/m2) and IFN (3 million units (MU), escalated weekly to 5 and 7 MU, Mon-Fri) to establish any dose limiting toxicity (DLT) and the maximum tolerated dose (MTD). Ten pts have been treated on the phase II trial. Pts completing 8 weeks of therapy were evaluable for response. Serum RA pharmacokinetics were determined using high-performance liquid chromatography (HPLC) on weeks 1 and 8 and peripheral blood lymphocytes (PBMCs) were obtained to measure changes in gene expression. Results: Toxicity: 1 of 6 pts treated at the 75 mg/m2 dose level experienced Grade 3 leukopenia, requiring cessation of treatment. Three pts were treated at the 90 mg/m2 dose level without a DLT establishing ATRA-IV at 90 mg/m2 as the MTD. To date, no pt from the phase II arm has experienced any Grade 3/4 toxicity. Response: In 20 pts evaluable for response, 5 (25%) have demonstrated a major response (1 complete response in a pt with lung-only metastases and 4 partial responses). 5 additional pts (25%) have experienced stable disease, lasting 16+, 12, 10, 9+, and 2+ months. HPLC analysis demonstrate no significant difference between weeks 1 and 8 in serum RA pharmacokinetics. Correlative studies on PBMCs are in progress. Conclusions: The combination of ATRA-IV administered once a week with IFN is well tolerated and possesses anti-tumor activity in pts with advanced RC. The sustained increased serum RA concentrations support use of the liposomal delivery system. We are currently evaluating whether in vivo expression of RA inducible genes, including retinoic acid receptor RARβ, correlates with clinical response. No significant financial relationships to disclose.

Involvement of serum retinoids and Leiden mutation in patients with esophageal, gastric, liver, pancreatic, and colorectal cancers in Hungary

To analyze the serum levels of retinoids and Leiden mutation in patients with esophageal, gastric, liver, pancreatic, and colorectal cancers. The changes in serum levels of retinoids (vitamin A, alpha- and beta-carotene, alpha- and beta-cryptoxanthin, zeaxanthin, lutein) and Leiden mutation were measured by high liquid performance chromatography (HPLC) and polymerase chain reaction (PCR) in 107 patients (70 males/37 females) with esophageal (0/8), gastric (16/5), liver (8/7), pancreatic (6/4), and colorectal (30/21 including 9 patients suffering from in situ colon cancer) cancer. Fifty-seven healthy subjects (in matched groups) for controls of serum retinoids and 600 healthy blood donors for Leiden mutation were used. The serum levels of vitamin A and zeaxanthin were decreased significantly in all groups of patients with gastrointestinal (GI) tumors except for vitamin A in patients with pancreatic cancer. No changes were obtained in the serum levels of alpha- and beta-carotene, alpha- and beta-cryptoxanthin, zeaxanthin, lutein in patients with GI cancer. The prevalence of Leiden mutation significantly increased in all groups of patients with GI cancer. Retinoids (as environmental factors) are decreased significantly with increased prevalence of Leiden mutation (as a genetic factor) in patients before the clinical manifestation of histologically different (planocellular and hepatocellular carcinoma, and adenocarcinoma) GI cancer.