[The development of portal hypertension and liver failure on the background of long-term intake of vitamin A in a young woman. Case report].

The use of over-the-Counter (OTC) pharmaceuticals is a common phenomenon in today's society. We present a case of liver injury associated with long-term OTC use of vitamin A. The young patient took daily up to 15 capsules of a combined preparation for 2 years containing retinol palmitate 55 mg (100,000 IU) + Alpha-Tocopherol acetate 100 mg, the content of vitamin A in which significantly exceeded the recommended daily dose. Gradually, the patient noted the appearance of arthralgia, skin itching, hyperemia of the palms and feet, exfoliation of the skin on the soles, profuse hair loss, cracks in the corners of the mouth and in the area of the earlobes. Patient's condition worsened with the development of signs of liver cirrhosis in the form of portal hypertension (ascites, splenomegaly) and a decrease in the protein-synthetic function of the organ. Chronic viral hepatitis, autoimmune hepatitis, primary biliary cirrhosis, hemochromatosis, Wilson's disease, alcoholic liver disease were exclude. Liver biopsy showed characteristic signs of hypervitaminosis A without fibrosis. A complete regression of symptoms was observe within 8 months after discontinuation of the drug. A toxicity can lead to serious liver injury and should be considere in the differential diagnosis of chronic liver disease. Vitamin A should only be prescribe for medical reasons, for a limited period of time, and under close medical supervision.

Low maternal vitamin A intake increases the incidence of teratogen induced congenital diaphragmatic hernia in mice.

BACKGROUND: Congenital diaphragmatic hernia (CDH) is a severe birth defect associated with high perinatal mortality and long-term morbidity. The etiology of CDH is poorly understood although abnormal retinoid signaling has been proposed to contribute to abnormal diaphragm development. Existing epidemiological data suggest that inadequate dietary vitamin A intake is a risk factor for developing CDH. METHODS: Using a mouse model of teratogen-induced CDH, the objective of this study was to test the hypothesis that low maternal vitamin A intake contributes to abnormal diaphragm development. To test this hypothesis, we optimized a model of altered maternal dietary vitamin A intake and a teratogenic model of CDH in mice that recapitulates the hallmark features of posterolateral diaphragmatic hernia in humans. RESULTS: Our data uniquely show that low maternal dietary vitamin A intake and marginal vitamin A status increases the incidence of teratogen-induced CDH in mice. CONCLUSION: Low dietary vitamin A intake and marginal vitamin A status lead to an increased incidence of teratogen-induced CDH in mice, highlighting the importance of adequate dietary vitamin A intake and CDH risk. IMPACT: This study describes and validates a mouse model of altered maternal and fetal vitamin A status. This study links existing epidemiological data with a mouse model of teratogen-induced congenital diaphragmatic hernia, highlighting the importance of low maternal vitamin A intake as a risk factor for the development of congenital diaphragmatic hernia. This study supports the Retinoid Hypothesis, which posits that the etiology of congenital diaphragmatic hernia is linked to abnormal retinoid signaling in the developing diaphragm.

All-trans-retinal induces autophagic cell death via oxidative stress and the endoplasmic reticulum stress pathway in human retinal pigment epithelial cells.

Failure of all-trans-retinal (atRAL) clearance contributes to retina degeneration. However, whether autophagy can be activated by excess atRAL accumulation in retinal pigment epithelial (RPE) cells is not known. This study showed that atRAL provoked mitochondria-associated reactive oxygen species (ROS) production, activated the nuclear factor (erythroid-derived 2)-like 2 and apoptosis in a human RPE cell line, ARPE-19 cells. Moreover, we found that autophagic flux was functionally activated after atRAL treatment. The antioxidant N-acetylcysteine attenuated the expression of autophagy markers, suggesting that ROS triggered atRAL-activated autophagy. In addition, autophagic cell death was observed in atRAL-treated RPE cells, while inhibition of autophagy with 3-methyladenine or LC3, Beclin1, p62 silencing ameliorated atRAL-induced cytotoxicity. Suppression of autophagy quenched mitochondrial ROS and inhibited HO-1 and γ-GCSh expression, indicating that atRAL-activated autophagy enhances intracellular oxidative stress, thereby promoting RPE cell apoptosis. Furthermore, we found that inhibiting endoplasmic reticulum (ER) stress suppressed atRAL-induced mitochondrial ROS generation, subsequently attenuated autophagy and apoptosis in RPE cells. Taken together, these results suggest that atRAL-induced oxidative stress and ER stress modulate autophagy, which may contribute to RPE degeneration. There may be positive feedback regulatory mechanisms between atRAL-induced oxidative stress and autophagy or ER stress.

Rubella Virus Infection, the Congenital Rubella Syndrome, and the Link to Autism.

Rubella is a systemic virus infection that is usually mild. It can, however, cause severe birth defects known as the congenital rubella syndrome (CRS) when infection occurs early in pregnancy. As many as 8%-13% of children with CRS developed autism during the rubella epidemic of the 1960s compared to the background rate of about 1 new case per 5000 children. Rubella infection and CRS are now rare in the U.S. and in Europe due to widespread vaccination. However, autism rates have risen dramatically in recent decades to about 3% of children today, with many cases appearing after a period of normal development ('regressive autism'). Evidence is reviewed here suggesting that the signs and symptoms of rubella may be due to alterations in the hepatic metabolism of vitamin A (retinoids), precipitated by the acute phase of the infection. The infection causes mild liver dysfunction and the spillage of stored vitamin A compounds into the circulation, resulting in an endogenous form of hypervitaminosis A. Given that vitamin A is a known teratogen, it is suggested that rubella infection occurring in the early weeks of pregnancy causes CRS through maternal liver dysfunction and exposure of the developing fetus to excessive vitamin A. On this view, the multiple manifestations of CRS and associated autism represent endogenous forms of hypervitaminosis A. It is further proposed that regressive autism results primarily from post-natal influences of a liver-damaging nature and exposure to excess vitamin A, inducing CRS-like features as a function of vitamin A toxicity, but without the associated dysmorphogenesis. A number of environmental factors are discussed that may plausibly be candidates for this role, and suggestions are offered for testing the model. The model also suggests a number of measures that may be effective both in reducing the risk of fetal CRS in women who acquire rubella in their first trimester and in reversing or minimizing regressive autism among children in whom the diagnosis is suspected or confirmed.

Liver transplantation for very severe hepatopulmonary syndrome due to vitamin A-induced chronic liver disease in a patient with Shwachman-Diamond syndrome.

Vitamin A intoxication is a rare cause of liver disease, but the risk increases in patients with underlying liver dysfunction. We present a patient with Shwachman-Diamond Syndrome who developed liver fibrosis, portal hypertension and very severe hepatopulmonary syndrome as a consequence of chronic vitamin A intoxication. She underwent successful liver transplantation with complete resolution of the pulmonary shunting.

Teratogenic potential of nanoencapsulated vitamin A evaluated on an alternative model organism, the tunicate Ciona intestinalis.

Nano-encapsulation is a technology used to pack substances in order to enhance their stability and bioavailability, but this packing may interact with living systems, causing unexpected toxicity. Vitamin A (vit A) is a substance that has received attention, because in developed countries, the increasing availability of supplements is leading to its excessive intake. This study aims to compare teratogenic effects caused by exposure to the traditional formulation of vit A versus nano-encapsulated vit A. We used ascidian embryos as an alternative model. Ascidians are marine organisms closely related to vertebrates that share with them a body plan and developmental programme, including the morphogenetic role of retinoic acid (RA). Our data showed that the adverse effects of exposure to the same concentration of the two formulations were different, suggesting that the nano-encapsulation increased the bioavailability of the molecule, which could be better absorbed and metabolised to RA, the effective teratogenic substance.

Photo-co-carcinogenesis of Topically Applied Retinyl Palmitate in SKH-1 Hairless Mice.

Cosmetic products that contain retinyl palmitate are popular as antiaging skin treatments; however, recent studies suggest a risk for enhanced skin tumor development with topical retinyl palmitate applications and exposure to solar ultraviolet radiation (UVR). In this study, we investigated the potential of retinyl palmitate to enhance UVR-induced photo-co-carcinogenesis. Groups of 36 male and 36 female SKH-1 hairless mice were exposed to simulated solar light (SSL) and treated with the control cream or creams containing retinyl palmitate, 5 days per week for 40 weeks. Other groups of mice were exposed to SSL and received no cream treatment or received cream treatments and were exposed to ultraviolet-A or ultraviolet-B. Mice were monitored for the development of skin tumors, and the incidences and multiplicities of squamous cell neoplasia were determined by histopathology. In both the absence and presence of SSL, mice administered the control cream developed skin tumors earlier and had higher incidences and multiplicities of skin squamous cell neoplasms than mice that received no cream treatment. Compared to the control cream groups, mice exposed to SSL and administered the retinyl palmitate creams demonstrated earlier onsets of skin tumors and had increased incidences and multiplicities of squamous cell skin neoplasms.

Functions of Intracellular Retinoid Binding-Proteins.

Multiple binding and transport proteins facilitate many aspects of retinoid biology through effects on retinoid transport, cellular uptake, metabolism, and nuclear delivery. These include the serum retinol binding protein sRBP (aka Rbp4), the plasma membrane sRBP receptor Stra6, and the intracellular retinoid binding-proteins such as cellular retinol-binding proteins (CRBP) and cellular retinoic acid binding-proteins (CRABP). sRBP transports the highly lipophilic retinol through an aqueous medium. The major intracellular retinol-binding protein, CRBP1, likely enhances efficient retinoid use by providing a sink to facilitate retinol uptake from sRBP through the plasma membrane or via Stra6, delivering retinol or retinal to select enzymes that generate retinyl esters or retinoic acid, and protecting retinol/retinal from excess catabolism or opportunistic metabolism. Intracellular retinoic acid binding-proteins (CRABP1 and 2, and FABP5) seem to have more diverse functions distinctive to each, such as directing retinoic acid to catabolism, delivering retinoic acid to specific nuclear receptors, and generating non-canonical actions. Gene ablation of intracellular retinoid binding-proteins does not cause embryonic lethality or gross morphological defects. Metabolic and functional defects manifested in knockouts of CRBP1, CRBP2 and CRBP3, however, illustrate their essentiality to health, and in the case of CRBP2, to survival during limited dietary vitamin A. Future studies should continue to address the specific molecular interactions that occur between retinoid binding-proteins and their targets and their precise physiologic contributions to retinoid homeostasis and function.

Maternal supplementation with a megadose of vitamin A reduces colostrum level of α-tocopherol: a randomised controlled trial.

BACKGROUND: Maternal supplementation with vitamin A is one of the strategies for controlling its deficiency in the mother-child dyad, although studies with animals showed that supplementation with high doses of vitamin A reduces the levels of α-tocopherol (vitamin E) in the mother's serum and milk. The objective of the present study was to assess the influence of maternal supplementation with vitamin A on the concentration of retinol and α-tocopherol in human milk. METHODS: Healthy puerperal women were randomly distributed into a control group (n = 44) and a supplemented group (n = 44). Blood and colostrum samples were collected after delivery, and mature milk samples were collected 30 days later. The supplemented group received 200 000 IU of retinyl palmitate after the first colostrum collection. The retinol and α-tocopherol levels in the samples were determined by high-performance liquid chromatography. RESULTS: The mean (SD) retinol and α-tocopherol levels in the maternal serum were considered adequate at 46.4 (15.9) and 1023.6 (380.4) µg dL(-1) , respectively. The colostrum retinol levels of the supplemented group increased significantly 24 h after the intervention (P < 0.001). However, the retinol levels in the mature milk of both groups did not differ (P > 0.05). Moreover, after maternal supplementation with vitamin A, the colostrum α-tocopherol level decreased by 16.4%, which is a significant reduction (P < 0.05). However, vitamin A supplementation did not affect the α-tocopherol level of mature milk (P > 0.05). CONCLUSIONS: Maternal supplementation with high doses of vitamin A increased the colostrum level of this nutrient but reduced the bioavailability of α-tocopherol, which may harm the newborn's health because newborns have limited vitamin E reserves.

Interphotoreceptor Retinoid-Binding Protein Mitigates Cellular Oxidative Stress and Mitochondrial Dysfunction Induced by All-trans-Retinal.

PURPOSE: Point and null mutations in interphotoreceptor retinoid-binding protein (IRBP) cause retinal dystrophy in affected patients and IRBP-deficient mice with unknown mechanism. This study investigated whether IRBP protects cells from damages induced by all-trans-retinal (atRAL), which was increased in the Irbp(-/-) retina. METHODS: Wild-type and Irbp(-/-) mice retinal explants in buffer with or without purified IBRP were exposed to 800 lux light for different times and subjected to retinoid analysis by high-performance liquid chromatography. Purity of IRBP was determined by Coomassie Brilliant Blue staining and immunoblot analysis. Cellular damages induced by atRAL in the presence or absence of IRBP were evaluated in the mouse photoreceptor-derived 661W cells. Cell viability and death were measured by 3-(4,5-dimethyl-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and TUNEL assays. Expression and modification levels of retinal proteins were determined by immunoblot analysis. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) were detected with fluorogenic dyes and confocal microscopy. Mitochondrial membrane potential was analyzed by using JC-1 fluorescent probe and a flow cytometer. RESULTS: Content of atRAL in Irbp(-/-) retinal explants exposed to light for 40 minutes was significantly higher than that in wild-type retinas under the same light conditions. All-trans-retinal caused increase in cell death, tumor necrosis factor activation, and Adam17 upregulation in 661W cells. NADPH oxidase-1 (NOX1) upregulation, ROS generation, NO-mediated protein S-nitrosylation, and mitochondrial dysfunction were also observed in 661W cells treated with atRAL. These cytotoxic effects were significantly attenuated in the presence of IRBP. CONCLUSIONS: Interphotoreceptor retinoid-binding protein is required for preventing accumulation of retinal atRAL, which causes inflammation, oxidative stress, and mitochondrial dysfunction of the cells.

Supplementation with vitamin A enhances oxidative stress in the lungs of rats submitted to aerobic exercise.

Exercise training induces reactive oxygen species production and low levels of oxidative damage, which are required for induction of antioxidant defenses and tissue adaptation. This process is physiological and essential to improve physical conditioning and performance. During exercise, endogenous antioxidants are recruited to prevent excessive oxidative stress, demanding appropriate intake of antioxidants from diet or supplements; in this context, the search for vitamin supplements that enhance the antioxidant defenses and improve exercise performance has been continuously increasing. On the other hand, excess of antioxidants may hinder the pro-oxidant signals necessary for this process of adaptation. The aim of this study was to investigate the effects of vitamin A supplementation (2000 IU/kg, oral) upon oxidative stress and parameters of pro-inflammatory signaling in lungs of rats submitted to aerobic exercise (swimming protocol). When combined with exercise, vitamin A inhibited biochemical parameters of adaptation/conditioning by attenuating exercise-induced antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and decreasing the content of the receptor for advanced glycation end-products. Increased oxidative damage to proteins (carbonylation) and lipids (lipoperoxidation) was also observed in these animals. In sedentary animals, vitamin A decreased superoxide dismutase and increased lipoperoxidation. Vitamin A also enhanced the levels of tumor necrosis factor alpha and decreased interleukin-10, effects partially reversed by aerobic training. Taken together, the results presented herein point to negative effects associated with vitamin A supplementation at the specific dose here used upon oxidative stress and pro-inflammatory cytokines in lung tissues of rats submitted to aerobic exercise.

Vitamin A and Retinoids as Mitochondrial Toxicants.

Vitamin A and its derivatives, the retinoids, are micronutrient necessary for the human diet in order to maintain several cellular functions from human development to adulthood and also through aging. Furthermore, vitamin A and retinoids are utilized pharmacologically in the treatment of some diseases, as, for instance, dermatological disturbances and some types of cancer. In spite of being an essential micronutrient with clinical application, vitamin A exerts several toxic effects regarding redox environment and mitochondrial function. Moreover, decreased life quality and increased mortality rates among vitamin A supplements users have been reported. However, the exact mechanism by which vitamin A elicits its deleterious effects is not clear yet. In this review, the role of mitochondrial dysfunction in the mechanism of vitamin A-induced toxicity is discussed.

Vitamin A dimers trigger the protracted death of retinal pigment epithelium cells.

Cellular events responsible for the initiation of major neurodegenerative disorders of the eye leading to blindness, including age-related macular degeneration, Stargardt and Best diseases, are poorly understood. Accumulation of vitamin A dimers, such as N-retinylidene-N-retinylethanolamine (A2E) in the retinal pigment epithelium (RPE), is one of the earliest measurable events preceding retinal degeneration. However, the extent to which these dimers contribute to tissue degeneration is not clear. To determine if A2E could trigger morphological changes associated with the degenerating RPE and subsequent cell death, we evaluated its toxicity to cultured human RPE cells (ARPE-19). We show that A2E triggered the accumulation of debris followed by a protracted death. A2E was up to ≈ 14-fold more toxic than its precursor, retinaldehyde. Measurements reveal that the concentration of A2E in the aged human eye could exceed the concentration of all other retinoids, opening the possibility of A2E-triggered cell death by several reported mechanisms. Findings suggest that accumulation of vitamin A dimers such as A2E in the human eye might be responsible for the formation of ubiquitous RPE debris, an early indication of retinal degeneration, and that preventing or reducing the accumulation of vitamin A dimers is a prudent strategy to prevent blindness.

ATP-binding cassette transporter ABCA4 and chemical isomerization protect photoreceptor cells from the toxic accumulation of excess 11-cis-retinal.

The visual cycle is a series of enzyme-catalyzed reactions which converts all-trans-retinal to 11-cis-retinal for the regeneration of visual pigments in rod and cone photoreceptor cells. Although essential for vision, 11-cis-retinal like all-trans-retinal is highly toxic due to its highly reactive aldehyde group and has to be detoxified by either reduction to retinol or sequestration within retinal-binding proteins. Previous studies have focused on the role of the ATP-binding cassette transporter ABCA4 associated with Stargardt macular degeneration and retinol dehydrogenases (RDH) in the clearance of all-trans-retinal from photoreceptors following photoexcitation. How rod and cone cells prevent the accumulation of 11-cis-retinal in photoreceptor disk membranes in excess of what is required for visual pigment regeneration is not known. Here we show that ABCA4 can transport N-11-cis-retinylidene-phosphatidylethanolamine (PE), the Schiff-base conjugate of 11-cis-retinal and PE, from the lumen to the cytoplasmic leaflet of disk membranes. This transport function together with chemical isomerization to its all-trans isomer and reduction to all-trans-retinol by RDH can prevent the accumulation of excess 11-cis-retinal and its Schiff-base conjugate and the formation of toxic bisretinoid compounds as found in ABCA4-deficient mice and individuals with Stargardt macular degeneration. This segment of the visual cycle in which excess 11-cis-retinal is converted to all-trans-retinol provides a rationale for the unusually high content of PE and its long-chain unsaturated docosahexaenoyl group in photoreceptor membranes and adds insight into the molecular mechanisms responsible for Stargardt macular degeneration.

Retinol-encapsulated water-soluble succinated chitosan nanoparticles for antioxidant applications.

The aim of this study was to stabilize all-trans-retinol (RE) by complexification with chitosan derivatives through H-bonding. Succinated chitosan (CHI-succ) with three different degrees (5, 10, 20 mol%) of succinylation were synthesized to form complexes with RE. Various weight ratios (w/w) of CHI-succ/RE complexes were prepared and characterized to produce stable complexes in nanometer size. The CHI-succ(0.20)/RE complex with approximate 250 nm in diameter was obtained using a CHI-succ(0.20) concentration of 0.005% (w/v) in double deionized water with various contents of RE. From fine-tuning the degree of succinylation and the weight ratio of the CHI-succ and RE, the formation of supramolecular complexes simultaneously improved water solubility and stability of RE. The cell viability of CHI-succ polymers and their RE complexes in 3T3 cells were all>85% relative to the control. The antioxidant ability of the CHI-succ(0.20)/RE complexes was significantly greater than that of pure RE using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay (p<0.01).

Skin phototoxicity of cosmetic formulations containing photounstable and photostable UV-filters and vitamin A palmitate.

The aim of this study was to evaluate the in vitro skin phototoxicity of cosmetic formulations containing photounstable and photostable UV-filters and vitamin A palmitate, assessed by two in vitro techniques: 3T3 Neutral Red Uptake Phototoxicity Test and Human 3-D Skin Model In Vitro Phototoxicity Test. For this, four different formulations containing vitamin A palmitate and different UV-filters combinations, two of them considered photostable and two of them considered photounstable, were prepared. Solutions of each UV-filter and vitamin under study and solutions of four different combinations under study were also prepared. The phototoxicity was assessed in vitro by the 3T3 NRU phototoxicity test (3T3-NRU-PT) and subsequently in a phototoxicity test on reconstructed human skin model (H3D-PT). Avobenzone presented a pronounced phototoxicity and vitamin A presented a tendency to a weak phototoxic potential. A synergistic effect of vitamin A palmitate on the phototoxicity of combinations containing avobenzone was observed. H3D-PT results did not confirm the positive 3T3-NRU-PT results. However, despite the four formulations studied did not present any acute phototoxicity potential, the combination 2 containing octyl methoxycinnamate (OMC), avobenzone (AVB) and 4-methylbenzilidene camphor (MBC) presented an indication of phototoxicity that should be better investigated in terms of the frequency of photoallergic or chronic phototoxicity in humans, once these tests are scientifically validated only to detect phototoxic potential with the aim of preventing phototoxic reactions in the general population, and positive results cannot predict the exact incidence of phototoxic reactions in humans.

Embryotoxicity of Psoralea corylifolia L.: in vivo and in vitro studies.

BACKGROUND: Psoralea corylifolia L. (PC) was commonly used to treat miscarriages clinically. The aim of this study was to examine its embryotoxicity in mice and embryonic stem cells (ESCs). METHODS: Quality control of PC extract including reference marker compounds, pesticide residues, and heavy metals was authenticated with HPLC, Gas chromatography-mass spectrometry (GC-MS), and inductively coupled plasma-mass spectrometry. Pregnant mice were randomly assigned into five groups and dosed with distilled water (G1), PC extract of 2 (G2), 4 (G3), or 8 g/kg/day (G4), and vitamin A (G5). Meanwhile, half maximal inhibitory concentration values for ESCs and 3T3 cells were identified in a cytotoxicity assay, and apoptosis in neuroepithelium was assessed by transmission electron microscopy. RESULTS: In the G4 group, a statistically significant decrease in the total fetus, live fetus, and gravid uterine weight, and increase in the resorbed fetus, postimplantation loss, and neuroepithelial apoptosis as well as maternal liver-weight were found (p < 0.05). CONCLUSIONS: PC extracts at 8 g/kg/day might cause fetal toxicity and maternal liver damage in mice, although it did not cause typical malformation and ESC's cytotoxicity in this experiment. Our data suggested that high dosage and long-term administration of PC preparations may not be safe for pregnant women.

Valproic acid downregulates RBP4 and elicits hypervitaminosis A-teratogenesis--a kinetic analysis on retinol/retinoic acid homeostatic system.

BACKGROUND: Valproic acid (VPA) is an antiepileptic and anti-migraine prophylactic drug. VPA exhibits two severe side effects, namely acute liver toxicity and teratogenicity. These side effects are usually seen at the genetic and somatic levels. The cited action mechanisms involve inhibition of histone deacetylase, hypofolatenemia, hyperhomocysteinemia, and reactive oxidative stress. The proteomic information associated with VPA teratogenicity is still unavailable. We hypothesized that proteomic analysis might help us identify functional proteins that could be relevantly affected by VPA, and this phenomenon could be very sensitive in early embryonic stage, resulting in VPA teratogenicity. METHODOLOGY/PRINCIPAL FINDINGS: Proteomic analysis on the chicken embryos at Hamburger and Hamilton (HH) stage 28 showed that there were significant downregulations of ovotransferrins, carbonic anhydrase-2, retinol binding protein-4 (RBP4), NADH cytochrome b5 reductase 2 (CYB5R2), apolipoprotein A1, and protein SET, together with upregulation of 60S ribosomal protein L22. Among these, RBP4 was the most significantly downregulated (-32%). Kinetic analysis suggested that this situation could trigger hypervitaminosis A (+39.3%), a condition that has been well known to induce teratogenesis.. CONCLUSIONS/SIGNIFICANCE: This is the first report showing that VPA dowregulates RBP4. Our finding not only has led to a possible mechanism of VPA teratogenesis, but also has initiated new preventive strategies for avoiding VPA teratogeneis.