The protective effect of vitamin A palmitate eye gel on the ocular surface during general anaesthesia surgery: a randomized controlled trial.

PURPOSE: To investigate the change in tear production associated with general anesthesia and the protective effect of vitamin A palmitate eye gel on the ocular surface during general anesthesia. METHODS: This double-blind, randomized clinical trial included patients undergoing non-ophthalmic surgery under general anesthesia who randomly received vitamin A palmitate eye gel and taping for one eye (Group A, n = 60) or taping alone for the other eye (Group B, n = 60). Symptom assessment in dry eye (SANDE) score, tear film break-up time (TBUT), corneal fluorescein staining (CFS) score, and Schirmer tear test I (STT-1) were analyzed under a hand-held slit lamp before anesthesia (T0), 0.5 h postoperatively (T1), and 24 h postoperatively (T2). RESULTS: At 0.5 h postoperatively, an increase in CFS score was observed in both groups (P < 0.05 in Group A and P < 0.01 in Group B), and the participants in Group A had less corneal abrasions than those in Group B. STT-1 significantly increased in Group A (P < 0.05), while it significantly decreased in Group B (P < 0.001). The changes between the two groups were statistically significant (P < 0.001). At 24 h postoperatively, both CFS score and STT-1 almost returned to baseline levels in the two groups. In both groups, the SANDE score and TBUT showed little change at 0.5 h and 24 h postoperatively (all P > 0.05). CONCLUSION: Vitamin A palmitate eye gel effectively protected the ocular surface and aqueous supplementation during general anesthesia. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry (ChiCTR2100052140) on 20/10/2021.

A promising food-grade protector for Retinyl acetate emulsions with fibrillated egg white.

This work presents a novel use of fibrous egg white protein (FEWP) in food preservation and nutraceutical applications. In this study, food-grade FEWP was used as an encapsulating material, along with chitosan (CS), to stabilize emulsions. The emulsion system was then used as a delivery system to improve the stability of retinyl acetate (RA). The structural and functional properties, as well as the stability and rheological behavior of the FEWP/CS copolymer, was investigated. The stability of RA-enriched emulsions was also evaluated. FEWP and CS stabilized emulsions exhibited smaller particle size and enhanced stability against different ionic strengths and storage periods. Additionally, RA-encapsulated emulsions stabilized by FEWP:CS (25:1 w/w) effectively inhibited apple browning. This study provides a promising strategy for delivering antioxidant components, highlighting its potential in food preservation and nutraceutical applications.

[Influence of chronic immobilization stress on vitamin status in rats fed different diets].

The influence of a stress factor, widespread in modern conditions, on the vitamin status has not been studied enough. At the same time, the negative stress impact can be aggravated against the background of unhealthy nutrition, which in turn affects the vitamin status of the organism. In this regard, the goal of the research was to evaluate the effect of chronic restrict stress on the vitamin supply in rats fed a diet with adequate and increased content of fat, sugar and cholesterol. Material and methods. The experiment was carried out on 37 growing male Wistar rats (initial body weight of 45±5 g) divided into 4 groups. Animals of the 1st (control) and the 2nd groups received a complete semi-synthetic diet (CSSD) (20% protein, 10% fat, 58% carbohydrates in the form of starch, 384 kcal/100 g) for 92 days. The levels of all vitamins and mineral elements in the rats' diets were adequate for growing rats. Rats of the 3rd and the 4th groups were fed a high-calorie, high-fat high-carbohydrate diet (HFHCD) (20% protein, 28% fat, 2% cholesterol, 18% carbohydrates in the form of starch, 20% sucrose, 511 kcal/100 g). Animals of groups 2 and 4 were subjected to daily 90-minute immobilization. The concentration of vitamins A (retinol and retinol palmitate) and E (α-tocopherol) in the blood serum and liver were determined by high-performance liquid chromatography, vitamins B1 and B2 in the liver and urine, as well as riboflavin in the blood serum and 4-pyridoxic acid (4-PA) in urine were determined by fluorimetric methods. Biochemical parameters of blood serum were determined on a biochemical analyzer; the total content of fat, triglycerides (TG) and cholesterol (CH) was determined in the liver. Results. Replacing CSSD with HFHCD, both under restraint stress and without, was accompanied by an increase in liver weight by 1.8-2.0 fold, in its fat content by 2.6-3.3 fold, cholesterol by 32.6-35.3 fold and TG - by 33.0-57.6 fold (p=<0.001). An increase in alanine aminotransferase (ALT) activity by 1.7-2.0 fold (p=<0.01), in low-density lipoprotein (LDL) cholesterol level by 5.4 fold (p=<0.05) and the atherogenic coefficient by 2.5 fold (p<0.01) as well as a decrease in creatinine and urea level (p=<0.05) in blood serum were revealed. Immobilization was accompanied by a decrease in body weight, liver and liver fat in rats fed both CSSD and HFHCD (p<0.05), but didn't affect the blood serum biochemical parameters, with the exception of an increase in ALT activity. If the activity of alkaline phosphatase (ALP) did not change during immobilization of rats fed the CSSD, then in animals fed the high-calorie diet it decreased by 37.5% (p=<0.05 from the control) under its increase against the background of restrict stress by 78.7% (p=<0.01) compared to the indicator of rats of the 3rd group. Immobilization of rats treated with CSSD was accompanied by an increase in both absolute serum α-tocopherol level and concentration correlated with the level of cholesterol and triglycerides by 26.0-57.5% (p<0.05), with a simultaneous decrease in its content in the liver per 1 g of wet tissue by 22.1% (p=0.041) relative to the indicators of intact animals. Immobilization reduced the level of retinol palmitate in the liver by 2.3 times (p<0.01), but did not affect retinol level in the blood serum. At the same time, indicators of B vitamin status (the content of vitamins B1 and B2 in the liver per 1 g of wet tissue and per organ, blood serum riboflavin level, urinary excretion of riboflavin and 4-PA) did not change, with the exception of thiamine urinary excretion, which reduced compared to the control by 38.8%. In rats fed HFHCD, immobilization had no additional effect on the supply with vitamins A and E. The content of vitamins B1 and B2 in the liver in terms of the whole organ was reduced by 14.0-26.7% relative to the indicator in animals of the 3rd group, not subjected to chronic stress, only due to differences in liver weight in animals of these groups. Conclusion. The data obtained indicate that chronic stress has a negative effect on the vitamin status of the body, worsening the supply with vitamins A, E and B1, and substantiate the feasibility of studying the mechanisms of this effect in order to develop effective vitamin complexes for the treatment and prevention of diseases caused by long-term stress.

LX-2 Stellate Cells Are a Model System for Investigating the Regulation of Hepatic Vitamin A Metabolism and Respond to Tumor Necrosis Factor α and Interleukin 1ß.

Hepatic stellate cells (HSCs) are the major site of vitamin A (retinol) esterification and subsequent storage as retinyl esters within lipid droplets. However, retinyl esters become depleted in many pathophysiological states, including acute and chronic liver injuries. Recently, using a liver slice culture system as a model of acute liver injury and fibrogenesis, a time-dependent increase and decrease in the apparent formation of the bioactive retinoid all-trans-retinoic acid (atRA) and retinyl palmitate was measured, respectively. This coincided with temporal changes in the gene expression of retinoid-metabolizing enzymes and binding proteins, that preceded HSC activation. However, the underlying mechanisms that promote early changes in retinoid metabolism remain unresolved. We hypothesized that LX-2 cells could be applied to investigate differences in quiescent and activated HSC retinoid metabolism. We demonstrate that the hypermetabolic state of activated stellate cells relative to quiescent stellate cells may be attributed to induction of STRA6, RBP4, and CYP26A1, thereby reducing intracellular concentrations of atRA. We further hypothesized that paracrine and autocrine cytokine signaling regulates HSC vitamin A metabolism in both quiescent and activated cells. In quiescent cells, tumor necrosis factor α dose-dependently downregulated LRAT and CRBP1 mRNA, with EC50 values of 30-50 pg/mL. Likewise, interleukin-1ß decreased LRAT and CRBP1 gene expression but with less potency. In activated stellate cells, multiple enzymes were downregulated, suggesting that the full effects of altered hepatic vitamin A metabolism in chronic conditions require both paracrine and autocrine signaling events. Further, this study suggests the potential for cell type-specific autocrine effects in hepatic retinoid signaling. SIGNIFICANCE STATEMENT: HSCs are the major site of vitamin A storage and important determinants of retinol metabolism during liver fibrogenesis. Here, two LX-2 culture methods were applied as models of hepatic retinoid metabolism to demonstrate the effects of activation status and dose-dependent cytokine exposure on the expression of genes involved in retinoid metabolism. This study suggests that compared to quiescent cells, activated HSCs are hypermetabolic and have reduced apparent formation of retinoic acid, which may alter downstream retinoic acid signaling.

Application of chiral stationary phases for the separation of vitamin A acetate isomers.

The separation of vitamin A acetate isomers is essential for quality assurance of e.g. nutrition supplements, cosmetics, and pharmaceutical ingredients. High performance liquid chromatography (HPLC) is currently the most suitable analytical method for tackling this challenging separation task. However, the existing methods based on normal phase chromatography (NPC) are poorly reproducible due to the typical disadvantages of NPC, such as long equilibration times and fluctuation in retention factors. A new reversed phase method developed in our labs allows the separation of the isomers applying a chiral stationary phase (CSP). This phase consists of an immobilized polysaccharide which can be used in every chromatographic mode. However, they are not typically used in reversed phase mode. Through the screening of various stationary phases with different polysaccharide based chiral selectors, the choice of the ideal stationary phase could be confirmed, allowing to draw conclusions about the retention mechanism. The CSP Chiralpak IG-3 was found to be the most suitable among the examined. Regarding the separation mechanism, the spatial helical structure of the polysaccharide derivatives was confirmed to be of particular significance. In addition to the stationary phase, the mobile phase was tested for optimization regarding composition, gradient parameters as well as temperature using chromatographic method optimization software for the sake of method robustness.

Fatty acid/monoglyceride type and amount modulate fat-soluble vitamin absorption from mixed assemblies in mice.

We investigated the effects of fatty acid/ monoglyceride type and amount on the absorption of fat-soluble vitamins. Micelles or vesicles made with either caprylic acid (CA) + monocaprylin (MC) or oleic acid (OA) + monoolein (MO) at low or high concentrations were infused in bile duct-ligated mice. Retinol + retinyl ester and γ-tocopherol intestinal mucosa contents were higher in mice infused with CA + MC than with OA + MO (up to + 350 % for vitamin A and up to + 62 %, for vitamin E; p < 0.05). Cholecalciferol intestinal mucosa content was the highest in mice infused with micelles with CA + MC at 5 mg/mL (up to + 105 %, p < 0.05). Retinyl ester plasma response was higher with mixed assemblies formed at low concentration of FA + MG compared to high concentration (up to + 1212 %, p < 0.05), while no difference in cholecalciferol and γ-tocopherol plasma responses were measured. No correlation between size or zeta potential and vitamin absorption was found. The impact of FA and MG on fat-soluble vitamin absorption thus differs from one vitamin to another and should be considered to formulate adequate vitamin oral or enteral supplements.

[Efficacy of 0.05% cyclosporine A combined with vitamin A palmitate in the treatment of meibomian gland dysfunction-related dry eye].

Objective: To evaluate the efficacy of 0.05% cyclosporine A eye drops combined with vitamin A palmitate eye gel in the treatment of dry eye associated with meibomian gland dysfunction (MGD). Methods: A single-center, prospective, randomized, parallel controlled trial design was used to include patients diagnosed with MGD-associated dry eye. The patients were randomly divided into three groups and administered with medications binocularly for 12 weeks. The CsA+VA group was given 0.05% cyclosporine A eye drops twice a day and vitamin A palmitate eye gel three times a day. The CsA+HA group was given 0.05% cyclosporine A eye drops twice a day and 0.1% sodium hyaluronate eye drops three times a day. The HA group was given 0.1% sodium hyaluronate eye drops 3 times a day. The OSDI score, tear meniscus height, fluorescein tear break-up time, Schirmer Ⅰ test (without anesthesia), tear film lipid layer thickness, meibomian gland morphology and function examination, and corneal fluorescein sodium staining score were evaluated at baseline, 4, 8, and 12 weeks after the initiation of the treatment, respectively. Results: A total of 120 patients with MGD-related dry eye met the enrollment criteria, but 10 patients were lost to follow-up; 110 patients were finally included for observation, including 36 patients in the CsA+VA group, 38 in the CsA+HA group and 36 in the HA group. The OSDI score, tear meniscus height, fluorescein tear break-up time and meibomian gland secretion of the 3 groups were significantly improved. At the 12th week of the treatment, the differences of the CsA+VA group [25.45±15.11, (0.30±0.13) mm, (3.72±1.40) s, (5.03±2.52) points] and the CsA+HA group [26.98±16.89, (0.27±0.10) mm, (4.34±1.76) s, (5.11±2.39) points] from the HA group [24.57±11.26, (0.24±0.06) mm, (3.18±1.11) s, (9.11±3.34) points] were statistically significant (P<0.05). Compared with the CsA+HA group [(68.39±26.66) nm], the tear film lipid layer thickness in the CsA+VA group [(72.61±23.65) nm] was significantly increased (P<0.05). In the CsA+VA group, the meibomian gland secretion characters and discharge capacity among patients with severe abnormalities [(6.28±2.59) and (5.89±2.77) points at the 12th week of treatment], moderate abnormalities [(4.27±2.02) and (4.64±2.02) points at the 12th week of treatment] and mild abnormalities [(2.80±0.84) and (2.60±0.55) points at the 12th week of treatment] were significantly different (P<0.05). Conclusion: 0.05% cyclosporine A combined with vitamin A palmitate can significantly improve the symptoms and signs of patients with MGD-related dry eye, especially the tear film lipid layer thickness and the meibomian gland secretion characters and discharge capacity in severe cases.

The association between several serum micronutrients and benign prostatic hyperplasia: Results from NHANES 2003-2006.

BACKGROUND: Benign prostatic hyperplasia (BPH) is a common condition that affects the quality of life of older men. Specific micronutrients, including retinol, retinyl esters, carotenoids, vitamin E, and vitamin C, have antioxidant and anti-inflammatory properties. However, the correlation between serum concentrations of these micronutrients and BPH is unclear. METHODS: We used data from the National Health and Nutrition Examination Survey (NHANES), which included 2067 representative US men. BPH was assessed using the self-reported questionnaire. This association was explored by adjusting for confounders using multivariate logistic regression. RESULTS: After fully adjusting for confounders, for every 0.01 µmol/L increase in serum retinyl esters, the risk of BPH increased by 2% (OR = 1.02; 95% CI: 1.01-1.03; p = 0.006). Based on the Bonferroni-corrected p-value, we found this correlation to be significant. One µmol/L increase in total carotenoids was associated with a 22% increase in BPH risk (OR = 1.22; 95% CI: 1.03-1.46; p = 0.025). By analyzing the correlation between different types of carotenoids and BPH, we also found that ß-carotenoids (OR = 1.43; 95% CI: 1.03-1.99; p = 0.036) was also positively correlated with BPH. The subgroup analysis revealed a positive correlation between serum vitamin E (OR = 1.02; 95% CI: 1.00-1.04; p = 0.018) and BPH in men under 60 years of age. Serum retinyl ester (OR = 1.02; 95% CI: 1.01-1.04; p = 0.008) and carotenoid (OR = 1.52; 95% CI: 1.22-1.87; p < 0.001) concentrations were positively correlated with BPH in men over 60 years of age. CONCLUSION: Our study suggests that excessive serum retinyl esters, total carotenoids, and especially ß-carotenoids are potential risk factors for BPH, and this association should be further investigated.

Confocal Raman imaging reveals the impact of retinoids on human breast cancer via monitoring the redox status of cytochrome c.

This paper expands the current state of knowledge on impact of retinoids on redox status of cytochrome c in cancers. Little is known how the expression of cytochromes may influence the development of cancers. We studied the effect of the redox status of the central iron ion in heme of cytochrome c. We determined the redox status of the iron ion in cytochrome c in mitochondria, cytoplasm, lipid droplets, and endoplasmic reticulum of the human breast cancer cells by Raman imaging. We incubated human breast adenocarcinoma cells (SK-BR-3) with retinoic acid, retinol and retinyl ester (palmitate) at concentration of 50 µM for 24 h. We recorded the Raman spectra and images of human breast cancer in vitro SK-BR-3 cells receiving redox stimuli by retinoic acid, retinol and retinyl ester (palmitate). The paper provides evidence that retinoic acid and retinol are pivotally important for mitochondrial energy homeostasis by controlling the redox status of cytochrome c in the electron transport chain controlling oxidative phosphorylation and apoptosis. We discussed the role of retinoids in metabolism and signaling of cancer cells. The paper provides experimental support for theoretical hypothesis how retinoic acid/retinol catalyse resonance energy transfer reactions and controls the activation/inactivation cycle of protein kinase PKCδ.

Retinyl Ester Analysis by Orbitrap Mass Spectrometry.

Retinoids are light-sensitive molecules that are normally detected by UV absorption techniques. Here we describe the identification and quantification of retinyl ester species by high-resolution mass spectrometry. Retinyl esters are extracted by the method of Bligh and Dyer and subsequently separated by HPLC in runs of 40 min. The retinyl esters are identified and quantified by mass spectrometry analysis. This procedure enables the highly sensitive detection and characterization of retinyl esters in biological samples such as hepatic stellate cells.

Effective, convenient, and green sample preparation for the determination of retinol and retinol acetate in human serum using pipette tip microextraction.

An efficient sample preparation based on pipette tip microextraction that can be used for the analysis of retinol in human serum has been developed. Altogether, nine commercial pipette tips were compared based on recovery, sample volume, use of organic solvent, handling difficulty, duration of the preparation process, price, and greenness of the method. Retinol acetate was used as the internal standard. The extraction efficiency for both compounds was evaluated to optimize and select the best pipette tip for sample preparation, which was the WAX-S XTR pipette tip containing an ion exchanger and salt. This tip combined solid phase extraction and salting-out assisted liquid‒liquid extraction. Satisfying recoveries of 100 and 80% for retinol and retinol acetate, respectively, and good repeatability were demonstrated. The action of this pipette tip was based on the clean-up workflow in which the interferences were retained on the sorbent. The presence of residual interferences in the extracted samples did not affect the HPLC separation of compounds of interest. The simplicity of the clean-up workflow reduced the time of the sample preparation compared to the bind-wash-elute counterpart workflow. The advantages of our technique are its environmental friendliness and cost effectiveness. The selected pipette tip with an excellent microextraction efficiency enables sample preparation in both clinical research and practice.

The synergistic effect of retinyl propionate and hydroxypinacolone retinoate on skin aging.

BACKGROUND: Aging is responsible for the majority of skin and soft tissue remolding in humans. Retinol and its derivatives or retinoids effectively intervene skin aging process. Nevertheless, retinoids usually induce skin intolerance, especially among the Chinese, and thus, their application to prevent skin aging is yet to be well accepted. The study of optimal composition and concentration of retinoids is necessary to offer strong antiaging efficacies with minimum irritations. Therefore, a better understanding of retinol and its derivatives is acutely needed to develop strategies to combat skin aging. OBJECTIVE: In this study, we aimed to determine the optimal ratio of two retinol derivatives-hydroxypinacolone retinoate (HPR) and retinyl propionate (RP) in terms of dermal remodeling and skin aging prevention-and to investigate their synergistic antiaging effects both in vitro and in vivo. METHODS: An in vitro human foreskin fibroblast (HFF-1) cell model was established to evaluate the cell viability of HPR and/or RP treatment. In addition, the antiaging and retinol receptor genes expressions in HFF-1 cells cotreated with HPR and RP were quantified. The in vivo adverse reaction evaluation of skincare serums containing various levels of retinol or the optimal HPR and RP combination termed Gravi-A was performed by 24 h patch tests in 33 subjects prior to the clinical research. Last but not the least, clinical research with 42 Chinese urban women was conducted to assess the in vivo antiaging efficacy of the skincare serum containing this optimal retinoid combination. RESULTS: The combination of HPR and RP at the weight ratio of 5:9 was shown to achieve the optimal in vitro antiaging performance. Coadministration of 5 µg/mL HPR and 9 µg/mL RP to HFF-1 cells promoted their proliferation at 24 h and synergistically enhanced the expressions of type IV collagen, CRBP-I, and RARB genes. In addition, the skincare serum containing HPR and RP combination at 5:9 weight ratio demonstrated superior in vivo anti-wrinkle and skin elasticity improvement benefits without any adverse reactions, while retinol in the same concentration exerted much higher adverse effect. Skin wrinkles, skin smoothness, TEWL, skin elasticity R2 and R5 were improved by 8.3%, 11.9%, 25.7%, 14.5%, and 22.6%, respectively, after 8-week use. CONCLUSION: Our results indicated the advanced antiaging effect of HPR and RP combination both in vitro and in vivo. In addition, little adverse effect was observed in this study, in comparison with retinol. This combination named as Gravi-A is a potential therapeutic strategy to prevent skin aging, especially for Chinese women.

PNPLA2 mobilizes retinyl esters from retinosomes and promotes the generation of 11-cis-retinal in the visual cycle.

Retinosomes are intracellular lipid bodies found in the retinal pigment epithelium (RPE). They contain retinyl esters (REs) and are thought to be involved in visual chromophore regeneration during dark adaptation and in case of chromophore depletion. However, key enzymes in chromophore regeneration, retinoid isomerase (RPE65), and lecithin:retinol acyltransferase (LRAT) are located in the endoplasmic reticulum (ER). The mechanism and the enzyme responsible for mobilizing REs from retinosomes remained unknown. Our study demonstrates that patatin-like phospholipase domain containing 2 (PNPLA2) mobilizes all-trans-REs from retinosomes. The absence of PNPLA2 in mouse eyes leads to a significant accumulation of lipid droplets in RPE cells, declined electroretinography (ERG) response, and delayed dark adaptation compared with those of WT control mouse. Our work suggests a function of PNPLA2 as an RE hydrolase in the RPE, mobilizing REs from lipid bodies and functioning as an essential component of the visual cycle.

Lipid droplets, the Holy Grail of hepatic stellate cells: In health and hepatic fibrosis.

Lipid droplets (LDs) are distinct morphological markers of hepatic stellate cells (HSCs). They are composed of a core of predominantly retinyl esters and triacylglycerols surrounded by a phospholipid layer; the latter harbors perilipins 2, 3, and 5, which help control LD lipolysis. Electron microscopy distinguishes between Types I and II LDs. Type I LDs are surrounded by acid phosphatase-positive lysosomes, which likely digest LDs. LD count and retinoid concentration are modulated by vitamin A intake. Alcohol consumption depletes hepatic retinoids and HSC LDs, with concomitant transformation of HSCs to fibrogenic myofibroblast-like cells. LD loss and accompanying HSC activation occur in HSC cell culture models. Loss of LDs is a consequence of and not a prerequisite for HSC activation. LDs are endowed with enzymes for synthesizing retinyl esters and triacylglycerols as well as neutral lipases and lysosomal acid lipase for breaking down LDs. HSCs have two distinct metabolic LD pools: an "original" pool in quiescent HSCs and a "new" pool emerging in HSC activation; this two-pool model provides a platform for analyzing LD dynamics in HSC activation. Besides lipolysis, LDs are degraded by lipophagy; however, the coordination between and relative contributions of these two pathways to LD removal are unclear. While induction of autophagy accelerates LD loss in quiescent HSCs and promotes HSC activation, blocking autophagy impairs LD degradation and inhibits HSC activation and fibrosis. This article is a critique of five decades of investigations into the morphology, molecular structure, synthesis, and degradation of LDs associated with HSC activation and fibrosis.

Structural changes of erythrocyte membrane revealed by 3D confocal optical profilometer.

We examined hematological changes influenced by the experimental hypervitaminosis A. The 3D confocal optical profilometer was applied for assessment of the erythrocytes' membrane structural changes influenced by an overdose of vitamin A. The blood smears were evaluated in terms of alterations of geometrical and optical parameters of erythrocytes for two groups of animals: oil base and retinol palmitate (n = 9 animals for each group). The results demonstrate that an overdose of retinol palmitate causes changes in the torus curvature and pallor of discocytes, their surface area and volume. The observed structural malformations of the shape of red blood cells become visible at the earlier preclinical stage of changes in animal state and behavior. With this in mind, the results of the study open a new area of research in the certain dysfunction diagnosis of red blood cells and have a great potential in the further development of new curative protocols.

Inhibitory Effects of Vitamin A and Its Derivatives on Cancer Cell Growth Not Mediated by Retinoic Acid Receptors.

Vitamin A is an important trace essential nutrient. Vitamin A is present as a retinyl ester in animal foods and as ß-carotene (provitamin A), which is a precursor of vitamin A, in plant foods such as green and yellow vegetables. After ingestion and absorption in the body, these are converted into retinol and stored as retinyl esters in stellate cells in the liver. The stored retinyl esters are decomposed into retinol as needed, and converted into the aldehyde retinal, which plays an important role in vision. Retinoic acid (RA) has a variety of effects. In particular, RA is used as a therapeutic agent for acute promyelocytic leukemia. This review will cover (1) elucidation of anti-refractory cancer effects of retinol (vitamin A) not mediated by RA receptors, (2) elucidation of anti-cancer effects of RA not mediated by RA receptors and (3) the development of candidate new anti-cancer agents that combine the actions of RA and retinol. Lessons learned from these findings are that vitamin A has anti-cancer activity not mediated by RA receptors; that nutritional management of vitamin A leads to prevention and treatment of cancer, and that new compounds developed from RA derivatives represent good anti-cancer drug candidates that are in various stages of clinical trials.

Development and validation of a method to deliver vitamin A to macrophages.

Macrophages are critical players in the development of atherosclerotic lesions, where they promote local and systemic inflammation. Macrophages engulf lipoproteins and cell debris upon entry into the arterial wall, becoming lipid-laden foam cells. While most lipids found in foam cells are triglyceride and cholesterol, these cells accumulate several other lipids with bioactive properties, such as vitamin A and carotenoids. Vitamin A has strong immunomodulatory actions in macrophages and other immune cells. For example, macrophages release vitamin A as retinoic acid to modulate T cell differentiation, but the implication of intracellular vitamin A stores in this process remains elusive due to the lack of an adequate experimental model to load vitamin A into macrophages. The purpose of this study was to develop a reliable method to deliver vitamin A to cultured murine macrophages. Our results show that thioglycolate-elicited peritoneal macrophages fail to take up significant levels of vitamin A when provided as free retinol. Cultured macrophages and macrophages in the peritoneal cavity can take up retinyl esters, either as retinyl ester-loaded serum or retinyl esters infused directly into the peritoneal cavity. HPLC analyses in macrophage lysates revealed that the intraperitoneal injection method results in a fourfold greater vitamin A loading efficiency than retinyl ester-loaded serum added to cultured cells. These two alternative methods provide an efficient and reliable methodology to load macrophages with vitamin A for downstream applications such as studies of gene regulation trafficking of intracellular vitamin A, and vitamin A release from macrophages.

Darier disease successfully treated with a topical agent containing vitamin A (retinyl palmitate), vitamin E, and urea.

Darier disease (DD), also called keratosis follicularis, is an autosomal dominant hereditary keratinization disorder that manifests as keratotic papules with plaques in seborrheic areas. There are no validated curative treatments for DD, with the majority of cases treated symptomatically. We report the efficacy of a topical over-the-counter agent which contains retinyl palmitate, vitamin E, and urea for a patient with DD. A 13-year-old girl had brown papules on her scalp, neck, shoulders, and axillae since entering elementary school. A skin biopsy revealed hyperkeratosis, suprabasal acantholysis, and dyskeratosis manifested as corps ronds and grains in the epidermis. Sanger sequencing found the previously reported heterozygous mutation c.1484C>T in ATP2A2. The application of an over-the-counter topical agent containing retinyl palmitate 2750 µg/g (5000 IU/g), tocopheryl acetate 20 mg/g, urea 200 mg/g, and monoammonium glycyrrhizinate 5 mg/g twice daily for 2 months improved the papules without serious adverse events. Oral or topical aromatic vitamin A analogs (retinoids) are often used to treat DD. However, several adverse events are associated with retinoid treatment, and many patients only undergo their intermittent use or discontinue the treatments. Retinyl palmitate is more stable and has a lower irritative profile than other retinoic acids. When applied topically, however, retinyl palmitate cannot penetrate the skin as well as retinol can. Some reports have noted that vitamin E increases the biological availability of vitamin A and that urea helps mechanical percutaneous drug delivery. Our case suggests that retinyl palmitate has a sufficient therapeutic effect when combined with vitamin E and urea. In conclusion, we propose that topical agents containing retinyl palmitate, vitamin E, and urea might have a satisfactory effect on the skin lesions of DD patients, without the serious risks of adverse events.

Changes in the serum metabolomic profiles of subjects with NAFLD in response to n-3 PUFAs and phytosterol ester: a double-blind randomized controlled trial.

Nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease and threatens human health worldwide. As shown in our previous study, co-supplementation with phytosterol ester (PSE) (3.3 g day-1) and n-3 polyunsaturated fatty acids (PUFAs) (450 mg eicosapentaenoic acid (EPA) + 1500 mg docosahexaenoic acid (DHA) per day) was more effective at ameliorating hepatic steatosis than treatment with PSE or n-3 PUFAs alone. In the present study, we further investigated the changes in the serum metabolic profiles of subjects with NAFLD in response to n-3 PUFAs and PSE. Thirty-one differentially altered serum metabolites were annotated using the nontargeted ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-Q-TOF-MSE) analysis technique. Multivariable statistical and clustering analyses showed that co-supplementation of n-3 PUFAs and PSE was more effective at improving metabolic disorders in patients with NAFLD than treatment with n-3 PUFAs or PSE alone. The regulated metabolic pathways included metabolism of retinol, linoleic acid, arachidonic acid, glycerophospholipid, sphingolipid, and steroid hormone biosynthesis. Overall, the co-supplementation of n-3 PUFAs and PSE significantly increased the serum levels of PUFA-containing phosphatidylcholine (PC), lysophosphatidylcholine (LysoPC), perillyl alcohol and retinyl ester in patients with NAFLD after 12 weeks of intervention, and the levels of PC (14:0/20:5, 15:0/20:5), LysoPC (20:5, 22:6) and retinyl ester correlated negatively with the degree of hepatic steatosis. The regulatory effect of co-supplementation of n-3 PUFAs and PSE on metabolomic profiles may explain their potential role in alleviating hepatic steatosis in patients with NAFLD.

KIAA1363 affects retinyl ester turnover in cultured murine and human hepatic stellate cells.

Large quantities of vitamin A are stored as retinyl esters (REs) in specialized liver cells, the hepatic stellate cells (HSCs). To date, the enzymes controlling RE degradation in HSCs are poorly understood. In this study, we identified KIAA1363 (also annotated as arylacetamide deacetylase 1 or neutral cholesterol ester hydrolase 1) as a novel RE hydrolase. We show that KIAA1363 is expressed in the liver, mainly in HSCs, and exhibits RE hydrolase activity at neutral pH. Accordingly, addition of the KIAA1363-specific inhibitor JW480 largely reduced RE hydrolase activity in lysates of cultured murine and human HSCs. Furthermore, cell fractionation experiments and confocal microscopy studies showed that KIAA1363 localizes to the endoplasmic reticulum. We demonstrate that overexpression of KIAA1363 in cells led to lower cellular RE content after a retinol loading period. Conversely, pharmacological inhibition or shRNA-mediated silencing of KIAA1363 expression in cultured murine and human HSCs attenuated RE degradation. Together, our data suggest that KIAA1363 affects vitamin A metabolism of HSCs by hydrolyzing REs at the endoplasmic reticulum, thereby counteracting retinol esterification and RE storage in lipid droplets.