Effects Of Retinoids Research Articles

The acyclic retinoid Peretinoin inhibits hepatitis C virus replication and infectious virus release in vitro.

Clinical studies suggest that the oral acyclic retinoid Peretinoin may reduce the recurrence of hepatocellular carcinoma (HCC) following surgical ablation of primary tumours. Since hepatitis C virus (HCV) infection is a major cause of HCC, we assessed whether Peretinoin and other retinoids have any effect on HCV infection. For this purpose, we measured the effects of several retinoids on the replication of genotype 1a, 1b, and 2a HCV in vitro. Peretinoin inhibited RNA replication for all genotypes and showed the strongest antiviral effect among the retinoids tested. Furthermore, it reduced infectious virus release by 80–90% without affecting virus assembly. These effects could be due to reduced signalling from lipid droplets, triglyceride abundance, and the expression of mature sterol regulatory element-binding protein 1c and fatty acid synthase. These negative effects of Peretinoin on HCV infection may be beneficial in addition to its potential for HCC chemoprevention in HCV-infected patients.

Transcriptional changes in organoculture of full‐thickness human skin following topical application of all‐trans retinoic acid

SynopsisObjectiveRetinoids are used as therapeutic agents for numerous skin diseases, for example, psoriasis, acne and keratinization disorders. The same substances have also been recognized in the treatment for hyperpigmentation disorders such as melasma.Other studies on photo-damaged skin have shown that retinoids reduce wrinkles, surface roughness, mottled pigmentation, and visual skin appearance as a whole. We tested the hypothesis that an organoculture of full-thickness human skin could be used as a preclinical model to investigate the retinoid transcriptional profile in human skin in vitro.MethodsFull-thickness skin explants were exposed to topically applied all-trans retinoic acid (RA) for 24 h. The gene expression profile was analysed using oligonucleotide microarrays, and data were validated with real-time (RT) PCR.ResultsWe showed that the expression of 93 genes was significantly altered more than twofold. Several of the altered genes, for example, KRT4, CYP26 and LCN2, have previously been shown to be affected by RA in keratinocyte monocultures, reconstructed epidermis and skin biopsies from patients treated topically or orally with RA. In addition, genes, such as SCEL, NRIP1, DGAT2, RDH12 EfnB2, MAPK14, SAMD9 and CEACAM6 not previously reported to be affected by RA in human skin, were identified for the first time in this study.ConclusionThe results in the present study show that full-thickness human explants represent a valuable pre-clinical model for studying the effects of retinoids in skin.RésuméObjectifLes rétinoïdes sont utilisés comme agents thérapeutiques pour de nombreuses maladies de la peau, p.ex. le psoriasis, l'acné et les troubles de la kératinisation. Les mêmes substances ont également été reconnues dans le traitement des troubles de l' hyperpigmentation tels que le melasma.D'autres études sur la peau photo-endommagée ont montré que les rétinoïdes réduisent les rides, la rugosité de la surface, la pigmentation tachetée, et l'aspect visuel de la peau dans son ensemble. Nous avons testé l'hypothèse selon laquelle une organoculture de épaisseur intégrale de la peau humaine pourrait être utilisée comme modèle préclinique pour étudier le profil transcriptionnel des rétinoïdes dans la peau humaine in vitro.MéthodesDes explants de peau intégrale ont été exposés à l'application topique de all-trans acide rétinoïque (RA) pendant 24 heures. Le profil d' expression des gènes a été analysé en utilisant des puces DNA array et les données ont été validées par (RT) -PCR.ResultatsNous avons montré que l'expression de 93 gènes a été modifiée de façon significative par plus d'un facteur 2. Plusieurs des gènes modifiés par exemple KRT4, CYP26 et LCN2 ont été montrés précédemment d'être affectés par RA dans les monocultures de kératinocytes, dans l'épiderme reconstruit et dans des biopsies cutanées de patients traités par voie topique ou par voie orale avec RA. En outre, des gènes tels que SCEL, NRIP1, DGAT2, RDH12 EfnB2, MAPK14, SAMD9 et CEACAM6 non signalés précédemment, sont touchés par RA dans la peau humaine, et ont été identifiés pour la première fois dans cette étude.ConclusionLes résultats de la présente étude montrent que les explants humains de pleine épaisseur représentent un modèle préclinique précieux pour l'étude des effets des rétinoïdes dans la peau.

Retinoic acid modulates intrahippocampal levels of corticosterone in middle-aged mice: consequences on hippocampal plasticity and contextual memory

It is now established that vitamin A and its derivatives, retinoic acid (RA), are required for cognitive functions in adulthood. RA hyposignaling and hyperactivity of glucocorticoid (GC) pathway appear concomitantly during aging and would contribute to the deterioration of hippocampal synaptic plasticity and functions. Furthermore, recent data have evidenced counteracting effects of retinoids on GC signaling pathway. In the present study, we addressed the following issue: whether the stimulation of RA pathway could modulate intrahippocampal corticosterone (CORT) levels in middle-aged mice and thereby impact on hippocampal plasticity and cognitive functions. We firstly investigated the effects of vitamin A supplementation and RA treatment in middle-aged mice, on contextual serial discrimination task, a paradigm which allows the detection of early signs of age-related hippocampal-dependent memory dysfunction. We then measured intrahippocampal CORT concentrations by microdialysis before and after a novelty-induced stress. Our results show that both RA treatment and vitamin A supplementation improve “episodic-like” memory in middle-aged mice but RA treatment appears to be more efficient. Moreover, we show that the beneficial effect of RA on memory is associated to an increase in hippocampal PSD-95 expression. In addition, intrahippocampal CORT levels are reduced after novelty-induced stress in RA-treated animals. This effect cannot be related to a modulation of hippocampal 11β-HSD1 expression. Interestingly, RA treatment induces a modulation of RA receptors RARα and RARβ expression in middle-aged mice, a finding which has been correlated with the amplitude of intrahippocampal CORT levels after novelty-induced stress. Taken together, our results suggest that the preventive action of RA treatment on age-related memory deficits in middle-aged mice could be, at least in part, due to an inhibitory effect of retinoids on GC activity.

Retinoids and pregnancy: an update

Key content The use and pharmacokinetics of retinoids. The main known teratogenic effects of retinoids are face, skull, cardiovascular, nervous system and thymic abnormalities. The pregnancy prevention programme must be adhered to when initiating retinoid treatment. Effective contraception should be continued for at least one month after cessation of retinoid treatment. Management options of pregnant women with recent retinoid use or exposure in early pregnancy; including involvement of the specialist multidisciplinary team. Learning objectives To understand the risk and in particular teratogenesis associated with exposure to retinoids peri‐conception. To raise awareness of the pregnancy prevention programme. To highlight the management options for women who become pregnant with recent retinoid use or exposure in early pregnancy. Ethical issues Termination of pregnancy with peri‐conceptual exposure to retinoids. Should isotretinoin be used so widely in the childbearing population when we are aware of its teratogenicity?

The Effect of Acyclic Retinoid on the Metabolomic Profiles of Hepatocytes and Hepatocellular Carcinoma Cells

Background/PurposeAcyclic retinoid (ACR) is a promising chemopreventive agent for hepatocellular carcinoma (HCC) that selectively inhibits the growth of HCC cells (JHH7) but not normal hepatic cells (Hc). To better understand the molecular basis of the selective anti-cancer effect of ACR, we performed nuclear magnetic resonance (NMR)-based and capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS)-based metabolome analyses in JHH7 and Hc cells after treatment with ACR.Methodology/Principal FindingsNMR-based metabolomics revealed a distinct metabolomic profile of JHH7 cells at 18 h after ACR treatment but not at 4 h after ACR treatment. CE-TOFMS analysis identified 88 principal metabolites in JHH7 and Hc cells after 24 h of treatment with ethanol (EtOH) or ACR. The abundance of 71 of these metabolites was significantly different between EtOH-treated control JHH7 and Hc cells, and 49 of these metabolites were significantly down-regulated in the ACR-treated JHH7 cells compared to the EtOH-treated JHH7 cells. Of particular interest, the increase in adenosine-5′-triphosphate (ATP), the main cellular energy source, that was observed in the EtOH-treated control JHH7 cells was almost completely suppressed in the ACR-treated JHH7 cells; treatment with ACR restored ATP to the basal levels observed in both EtOH-control and ACR-treated Hc cells (0.72-fold compared to the EtOH control-treated JHH7 cells). Moreover, real-time PCR analyses revealed that ACR significantly increased the expression of pyruvate dehydrogenase kinases 4 (PDK4), a key regulator of ATP production, in JHH7 cells but not in Hc cells (3.06-fold and 1.20-fold compared to the EtOH control, respectively).Conclusions/SignificanceThe results of the present study suggest that ACR may suppress the enhanced energy metabolism of JHH7 cells but not Hc cells; this occurs at least in part via the cancer-selective enhancement of PDK4 expression. The cancer-selective metabolic pathways identified in this study will be important targets of the anti-cancer activity of ACR.

In vitro inhibition of mumps virus by retinoids.

BackgroundMumps virus (MuV) is a highly infectious paramyxovirus closely related to measles virus (MeV). Despite the availability of a mumps vaccine, outbreaks continue to occur and no treatment options are available. Vitamin A and other naturally occurring retinoids inhibit the replication of MeV in vitro.MethodsAnti-viral effects of retinoids were observed in cell culture using the myelomonocytic U937, NB4/R4, and Huh7/7.5 cells. Observations of anti-viral effect were quantified using TCID50 analysis. Molecular properties of the antiviral effect were analysed using quantitative RT-PCR and western blot.ResultsThe current work demonstrates that retinoids inhibit MuV in vitro due to up-regulation of type I interferon (IFN) and IFN stimulated genes. This effect is mediated by nuclear retinoid receptor signalling and RIG-I is required. The antiviral retinoid-induced state makes cells less permissive to viral replication from subsequent challenge with either MuV or MeV for less than 12 hours.ConclusionsThese results demonstrate that retinoids inhibit MuV replication in uninfected bystander cells through a retinoid inducible gene I (RIG-I), retinoic acid receptor (RAR) and IFN dependent manner making them refractory to subsequent rounds of viral replication. These observations raise the possibility that pharmacological doses of retinoids might have clinical benefit in MuV infection.

An in vitro model for the pro‐fibrotic effects of retinoids: mechanisms of action

Retinoids, including all-trans retinoic acid (tRA), have dose-dependent pro-fibrotic effects in experimental kidney diseases. To understand and eventually prevent such adverse effects, it is important to establish relevant in vitro models and unravel their mechanisms. Fibrogenic effects of retinoids were assessed in NRK-49F renal fibroblasts using picro-Sirius red staining for collagens and quantified by spectrophotometric analysis of the eluted stain. Other methods included RT-qPCR, immunoassays and matrix metalloproteinase (MMP) activity assays. With or without TGF-β1, tRA was dose-dependently pro-fibrotic, notably increasing collagen accumulation. tRA and TGF-β1 additively suppressed expression of mRNA for MMP2, 3 and 13 and suppressed MMP activity. tRA, in the presence of TGF-β1, induced plasminogen activator inhibitor-1 (PAI-1) mRNA and they additively induced PAI-1 protein expression. A PAI-1 inhibitor, a pan-retinoic acid receptor (RAR) antagonist and a pan-retinoid X receptor (RXR) antagonist each partially prevented the pro-fibrotic effect of tRA. The dose-dependent pro-fibrotic effects of a pan-RXR agonist were similar to those of tRA. A pan-RAR agonist showed weaker, less dose-dependent pro-fibrotic effects and the pro-fibrotic effects of RARα and RARβ-selective agonists were even smaller. An RARγ-selective agonist did not affect fibrogenesis. An in vitro model for the pro-fibrotic effects of retinoids was established in NRK-49F cells. It was associated with reduced MMP activity and increased PAI-1 expression, and was probably mediated by RXR and RAR. To avoid or antagonize the pro-fibrotic activity of tRA, further studies on RAR isotype-selective agonists and PAI-1 inhibitors might be of value.

Effects of Retinoids in Mouse Models of Colitis

In vitro and in vivo data have shown that retinoid treatment promotes an anti-inflammatory milieu with few adverse effects toward the gastrointestinal tract. The in vivo studies reported here further evaluate retinoid effects in 2 mouse models of inflammatory bowel disease. Chronic dextran sulfate sodium colitis was induced in age- and weight-matched C57Bl/6 mice by 4 cycles of dextran sulfate sodium administration (6-8 animals/group). At cycle 4, animals were administered 13-cis-retinoic acid (isotretinoin, 30 mg/kg) or vehicle (oral gavage) or 4-oxo-13-cis-retinoic acid (15 mg/kg, intraperitoneal) daily. T-cell transfer colitis was induced in CB17 SCID mice by transfer of naive CD4CD62L T cells and treated by transfer of regulatory CD4CD25 T cells (4-6 animals/group); isolated from BALB/c mice after treatment with isotretinoin or vehicle, as above, for 2 weeks. Assessments included endoscopic and histological scores, myeloperoxidase activity, serum cytokines, and plasma isotretinoin levels. Retinoid-treated animals with colitis showed comparable changes in myeloperoxidase activity, and endoscopic and histological scores, versus untreated animals with colitis. Modest and comparable changes were seen in body weight and colon length in animals injected with naive T cells from isotretinoin-treated donors versus those injected with T cells from vehicle-treated donors. Retinoid treatment was consistently associated with lower interleukin-12 levels, which, after the transfer of naive T cells from isotretinoin-treated donors, supported isotretinoin-mediated predisposition of naive T cells toward reduced proinflammatory cytokine expression. Colitis had no effect on isotretinoin exposure. Retinoids attenuate the proinflammatory cytokine response in vivo, with only modest effects on body weight and parameters of gastrointestinal morphology.

Deficiency of Retinaldehyde Dehydrogenase 1 Induces BMP2 and Increases Bone Mass In Vivo

The effects of retinoids, the structural derivatives of vitamin A (retinol), on post-natal peak bone density acquisition and skeletal remodeling are complex and compartment specific. Emerging data indicates that retinoids, such as all trans retinoic acid (ATRA) and its precursor all trans retinaldehyde (Rald), exhibit distinct and divergent transcriptional effects in metabolism. Despite these observations, the role of enzymes that control retinoid metabolism in bone remains undefined. In this study, we examined the skeletal phenotype of mice deficient in retinaldehyde dehydrogenase 1 (Aldh1a1), the enzyme responsible for converting Rald to ATRA in adult animals. Bone densitometry and micro-computed tomography (µCT) demonstrated that Aldh1a1-deficient (Aldh1a1−/−) female mice had higher trabecular and cortical bone mass compared to age and sex-matched control C57Bl/6 wild type (WT) mice at multiple time points. Histomorphometry confirmed increased cortical bone thickness and demonstrated significantly higher bone marrow adiposity in Aldh1a1−/− mice. In serum assays, Aldh1a1−/− mice also had higher serum IGF-1 levels. In vitro, primary Aldh1a1−/− mesenchymal stem cells (MSCs) expressed significantly higher levels of bone morphogenetic protein 2 (BMP2) and demonstrated enhanced osteoblastogenesis and adipogenesis versus WT MSCs. BMP2 was also expressed at higher levels in the femurs and tibias of Aldh1a1−/− mice with accompanying induction of BMP2-regulated responses, including expression of Runx2 and alkaline phosphatase, and Smad phosphorylation. In vitro, Rald, which accumulates in Aldh1a1−/− mice, potently induced BMP2 in WT MSCs in a retinoic acid receptor (RAR)-dependent manner, suggesting that Rald is involved in the BMP2 increases seen in Aldh1a1 deficiency in vivo. Collectively, these data implicate Aldh1a1 as a novel determinant of cortical bone density and marrow adiposity in the skeleton in vivo through modulation of BMP signaling.

Differential and Isomer-Specific Modulation of Vitamin A Transport and the Catalytic Activities of the RBP Receptor by Retinoids

Retinoids are vitamin A derivatives with diverse biological functions. Both natural and artificial retinoids have been used as therapeutic reagents to treat human diseases, but not all retinoid actions are understood mechanistically. Plasma retinol binding protein (RBP) is the principal and specific carrier of vitamin A in the blood. STRA6 is the membrane receptor for RBP that mediates cellular vitamin A uptake. The effects of retinoids or related compounds on the receptor's vitamin A uptake activity and its catalytic activities are not well understood. In this study, we dissected the membrane receptor-mediated vitamin A uptake mechanism using various retinoids. We show that a subset of retinoids strongly stimulates STRA6-mediated vitamin A release from holo-RBP. STRA6 also catalyzes the exchange of retinol in RBP with certain retinoids. The effect of retinoids on STRA6 is highly isomer-specific. This study provides unique insights into the RBP receptor's mechanism and reveals that the vitamin A transport machinery can be a target of retinoid-based drugs.

Biphasic pro-melanogenic and pro-apoptotic effects of all-trans-retinoic acid (ATRA) on human melanocytes: Time-course study

BackgroundThe effects of retinoids on melanogenesis and their mechanism as depigmenting agents in topical therapy have not been fully elucidated. Conflicting data about their impact on melanogenic pathways have been reported. ObjectiveTo investigate the effects of all-trans-retinoic acid (ATRA) on normal human melanocytes from Caucasian subjects. MethodsWe assessed ATRA's cytotoxicity by measuring viability with a cell proliferation assay, and apoptotic effects using Annexin V and γ-H2AX markers. ATRA's melanogenic activity was investigated based on spectrophotometric measurement of melanin content and tyrosinase enzymatic activity. Tyrosinase expression was assessed by Western blotting. We tested the antioxidant activity of superoxide dismutase (SOD) and catalase (CAT) in melanocytes using a spectrophotometric assay. ResultsOf the concentrations tested in this 72h time-course study, the 1.0μM ATRA had a well-defined two-stage pro-melanogenic and pro-apoptotic effect on melanocytes. In the first 6h, treated cells showed significant increase (p≤0.01) of melanin content, tyrosinase, SOD, and CAT activities compared to the controls. While overall tyrosinase expression was not affected by ATRA, all other tested parameters decreased progressively beyond the short-term point of 6h. ATRA treatment of over 6h induced melanocyte apoptosis, as shown by the time-dependent decrease in cell viability, coupled with significant increase in Annexin V positive cells and nuclear accumulation of γ-H2AX foci. ConclusionThe results obtained using this testing platform show a biphasic ATRA action: immediate pro-melanogenic effect and longer-term exposure pro-apoptotic activity. These data qualify ATRA as a potent tool to better understand the mechanisms that regulate the pigmentary system.

Retinoids for preventing the progression of cervical intra-epithelial neoplasia.

Invasive cervical carcinoma is preceded by a precancerous phase, cervical intra-epithelial neoplasia (CIN), which can be detected on cervical smears and confirmed by colposcopy and biopsy. Moderate and severe cases of intra-epithelial neoplasia (CIN2 and CIN3) are treated mainly with surgery to prevent progression to invasive carcinoma. Medical methods of preventing the progression or inducing the regression of CIN are needed. Retinoids are potent modulators of epithelial cell growth and differentiation that may have potential for the treatment of CIN. To ascertain whether retinoids can cause regression or prevent progression of CIN. We searched the Cochrane Gynaecological Cancer Review Group's Specialised Register and Non-Trials Database, the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3, 2010), and MEDLINE and EMBASE (July 2010).For the 2013 update, the searches were re-run as follows: CENTRAL, Issue 3, 2013; MEDLINE, April, Week 2, 2013; and EMBASE, Week 16, 2013. Randomized controlled trials (RCTs) and non-RCTs of retinoids for treating CIN in women. Two review authors independently assessed trial quality and extracted data from the trials. Adverse effects information was also collected from the trials. Five RCTs comparing the efficacy of four different retinoids were identified. Two studies examined the effects on CIN2 and CIN3 of the retinoids N-(4-hydroxyphenyl)retinamide (fenretinide) and 9-cis-retinoic acid (aliretinoin) given orally. Two examined the effect of all-trans-retinoic acid administered topically to the cervix. The fifth study investigated the use of 13-cis-retinoic acid (isotretinoin) given orally to human immunodeficiency virus (HIV)-positive participants with CIN1 and condyloma.Four studies reported no significant effect of retinoids on the progression to higher grades of CIN, and the fifth did not report data on progression. In all studies retinoids had no significant effect on regression of CIN3. Two studies reported that retinoids were associated with regression of CIN2. One reported a greater complete regression of CIN2 over that seen with placebo, which was of borderline statistical significance (odds ratio (OR) 0.5, 95% confidence interval (CI) 0.25 to 1.02). The other study reported a nonsignificant dose-related trend toward increased rates of complete and partial regression compared with placebo. One study reported significantly worse outcomes in women receiving retinoid (OR for regression 6.00, 95% CI 1.00 to 35.91). In general, the retinoid medications were well tolerated.In the 2010 review and in this update, no new studies were identified for inclusion. The retinoids studied are not effective in causing regression of CIN3 but may have some effect on CIN2. The data on CIN1 are inadequate. Retinoids are not effective in preventing progression of CIN of any grade. At the doses given for the duration of treatment studied, the retinoids were reasonably well tolerated.

Psoriasis treatment should be stratified in order to better assess the cardiovascular event rates

We have read with great interest the recently published article entitled ‘Cardiovascular disease event rates in patients with severe psoriasis treated with systemic anti-inflammatory drugs: a Danish real-world cohort study’ by Ahlehoff et al. 1. In that very well-presented article, they aimed to evaluate the rates of cardiovascular disease events in patients with severe psoriasis treated with systemic anti-inflammatory drugs. They concluded that in this nation-wide study of patients with severe psoriasis treated with systemic anti-inflammatory therapies, the use of biological agents and methotrexate was associated with lower rates of death, myocardial infarction and stroke compared with patients treated with other agents. Systemic treatments for psoriasis including methotrexate, cyclosporine, retinoids and biological agents may contribute to either reducing or increasing the cardiovascular risk 2. Indeed, it has been reported that American veterans affected by psoriasis treated with moderate doses of methotrexate have a reduced risk of major cardiovascular events compared with nontreated patients. This effect is possibly attributable to the anti-inflammatory effects of the drug 3. Cyclosporine and retinoids may increase serum cholesterol and triglycerides. Therefore, cyclosporine and retinoids should be chosen with caution in patients with cardiovascular risk factors. Furthermore, in patients with psoriasis, systemic anti-inflammatory therapy with tumour necrosis factor-alpha inhibitors may reduce the incidence of cardiovascular disease, and it can reduce endothelial cell activation 2. The present study concluded that patients with severe psoriasis or on systemic anti-inflammatory treatment with biological agents or methotrexate had reduced cardiovascular disease event rates. But the effects of cyclosporine and retinoids on cardiovascular event risk have not been determined exactly. In a study by Balci et al., no association between acitretin use and subclinical atherosclerosis was found 4. As we know, long-term management of severe psoriasis requires an individualized approach. The selection of a treatment is based on the clinical presentation of psoriasis and whether contraindications might exist. Most psoriasis treatments should be prescribed for restricted periods of time 5. Rotational treatment is a practical approach to reduce the cumulative toxicity and allow effective treatments to be maintained for many years 6. In the present study, patients with severe psoriasis were divided into three treatment groups: as biological agents, methotrexate and other therapies like retinoids, cyclosporine, phototherapy and/or climate therapy. In our opinion, we think that it would be better if the effects of each agent on cardiovascular disease were investigated separately. More severe psoriasis was significantly associated with the following: longer disease duration; higher prevalence of concomitant disease; greater involvement of the nails, scalp, flexures, palms and soles; and a poorer quality of life 7. Severe psoriasis is also associated with increased risk of adverse cardiovascular events and all-cause mortality 8, 9. In our opinion, in the present study, the activity of the disease before starting treatment, the duration of the disease and the presence of psoriatic arthritis should also have been determined. Coronary artery disease (CAD) is the major cause of deaths worldwide 10. Systolic heart failure is the most common cause of mortality in patients with CAD. Diabetes mellitus, hypertension, hyperlipidaemia and modifiable risk factors like obesity, smoking and alcohol are the most prominent risk factors for CAD 11. Furthermore, the prognosis of CAD may be associated with risk factors including increasing age, duration of diabetes and hypertension, obstructive sleep apnoea, obesity, lifestyle programmes and psychological disturbances. In addition to standard biochemical [sodium, potassium, creatinine/estimated glomerular filtration rate (eGFR)] and haematological tests (haemoglobin, haematocrit, ferritin, leucocytes and platelets), thyroid-stimulating hormone (thyrotropin) representing a thyroidal disorder can affect the prognosis of patients with CAD. In this point of view, it would be useful, if further effort was held on to assess these factors. In conclusion, severe psoriasis treated with systemic anti-inflammatory therapies, the use of biological agents and methotrexate were associated with lower rates of CAD mortality and morbidity as presented in this study. However, risk factors for CAD and the systemic anti-inflammatory therapies for psoriasis are very complex, so they deserve further large-scale prospective randomized clinical trials. We also believe that those findings obtained from this study will lead to further large-scale studies examining the relationship between CAD events and severe psoriasis. No conflict of interest was declared.

The effects of vitamin A on cells of innate immunity in vitro

Retinoid treatment is suggested to promote development of inflammatory bowel disease, although preclinical studies are not supportive. We evaluated the effect of retinoids on cytokine response in in vitro-differentiated human dendritic cells (ivDCs) and macrophages (ivMACs) derived from healthy human donors and in cultured human THP-1 cells. Effect on human intestinal epithelial cell integrity was also assessed. Each cell type was incubated (±lipopolysaccharide [LPS]) with all-trans retinoic acid (ATRA), 13-cis-RA (isotretinoin) and 4-oxo-13-cis-RA. Cytokine analysis was performed by array analysis. Cultured human endothelial colorectal adenocarcinoma (Caco-2) cells were incubated with these retinoids and media analyzed for leakage by spectrofluorometric analysis. ATRA consistently and significantly inhibited LPS-induced release of the pro-inflammatory cytokines tumor necrosis factor, interleukin (IL)-6, macrophage inflammatory protein (MIP)-1α and MIP-1β. All retinoids tested stimulated release of the anti-inflammatory cytokines granulocyte–macrophage colony-stimulating factor and IL-10, and also monocyte chemotactic protein-1, vascular endothelial growth factor and eotaxin-1. Incubation with retinoids did not significantly alter the permeability of Caco-2 monolayers. Pre-treatment of each cell type with retinoids promoted an anti-inflammatory cytokine profile with only minimal effect on intestinal epithelial cell permeability; consistent with in vivo studies.

Retinoid derivatives offer anti‐inflammatory benefits by promoting neutrophil apoptosis and inhibiting proinflammatory mediator production in a model of bovine respiratory disease

Clearance of apoptotic neutrophils (PMN) following infection is critical for the resolution of inflammation. Despite demonstrating immunomodulatory properties, the effects of retinoids in PMN in the context of an inflammatory response remain unknown.Objectiveto evaluate the immunomodulatory properties of two retinoids, oxidatively‐transformed carotene‐β (OxC‐β) and retinoic acid (RA) in a model of Mannheimia haemolytica‐induced bovine respiratory disease, which is characterized by severe inflammation.Resultsin vitro, RA and OxC‐β induced caspase‐and time‐dependent apoptosis, but not necrosis, in bovine PMN, but not epithelial cells or fibroblasts. Neither RA nor OxC‐β affected PMN function. In M. haemolytica‐infected calves (2×107 CFU), animals that received a 28‐day dietary OxC‐β treatment (10 mg/kg) had elevated apoptotic leukocytes and reduced LTB4 levels in their lower airways 3h post‐infection vs infected‐untreated calves.ConclusionRA and OxC‐β promote cell‐specific apoptosis and inhibit the production of pro‐inflammatory LTB4, both mechanisms that promote the resolution of inflammation, thereby suggesting an anti‐inflammatory role for retinoid derivatives. Supported by NSERC and AIHS.

Differential Effects of Retinoids and Inhibitors of ERK and p38 Signaling on Adipogenic and Myogenic Differentiation of P19 Stem Cells

All-trans-retinoic acid (atRA) is an essential signaling molecule in embryonic development. It regulates cell differentiation by activating nuclear retinoic acid receptors (RAR) and retinoid-X receptors (RXR), which both control gene expression. In addition, atRA could act in the cytoplasm by modulating the activity of mitogen-activated protein kinases (MAPK) ERK and p38, which also have a role in cell differentiation. AtRA can induce the differentiation of P19 embryonic carcinoma stem cells into adipocytes, cardiomyocytes, and skeletal muscle cells, concurrently, in the same culture. We postulated that combinations of atRA, atRA analogs exhibiting selectivity for RAR or RXR, and inhibitors of ERK and p38 signaling (ERKi and p38i) could be used to favor one mesodermal fate over the others in the P19 model. In a first series of experiments, we replaced atRA by an agonist of RXR (LG100268) or RAR (TTNPB) to preferentially stimulate one group of receptors over the other. LG100268 was as adipogenic and myogenic as atRA, whereas TTNPB strongly induced adipogenesis, but not myogenesis. ERKi enhanced the myogenic action of atRA, and p38i increased both adipogenesis and myogenesis. In a second series of experiments, we combined atRA with an RAR or RXR antagonist (RARatg or RXRatg) to preferentially deactivate each receptor group in turn. The combinations atRA+RXRatg and atRA+RARatg, including or not ERKi, had similar mesodermal actions as atRA. In contrast, there was no myogenesis with atRA+RXRatg+p38i treatment, and there were no myogenesis and no adipogenesis with the atRA+RARatg+p38i combination. Overall, the results indicate that p38 has a role in mesodermal differentiation that depends on the retinoid context. Indeed, p38 in conjunction with RXR is important in myogenesis, and p38 and RAR in adipogenesis. Under the conditions tested, it was possible to stimulate adipogenesis with a block on myogenesis, whereas increased myogenesis was accompanied by adipogenesis.

Retinoid Acid Specifies Neuronal Identity through Graded Expression of Ascl1

SummaryCell diversity and organization in the neural tube depend on the integration of extrinsic signals acting along orthogonal axes. These are believed to specify distinct cellular identities by triggering all-or-none changes in expression of combinations of transcription factors [1]. Under the influence of a common dorsoventral signal, sonic hedgehog, and distinct anterior-posterior (A-P) inductive signals [2, 3], two topographically related progenitor pools that share a common transcriptional code produce serotonergic and V3 neurons in the hindbrain and spinal cord, respectively [4–7]. These neurons have different physiological properties, functions, and connectivity [8, 9]. Serotonergic involvement in neuropsychiatric diseases has prompted greater characterization of their postmitotic repertoire of fate determinants, which include Gata2, Lmx1b, and Pet1 [10], whereas V3 neurons express Sim1 [4]. How distinct serotonergic and V3 neuronal identities emerge from progenitors that share a common transcriptional code is not understood. Here, we show that changes in retinoid activity in these two progenitor pools determine their fates. Retinoids, via Notch signaling, control the expression level in progenitors of the transcription factor Ascl1, which selects serotonergic and V3 neuronal identities in a dose-dependent manner. Therefore, quantitative differences in the expression of a single component of a transcriptional code can select distinct cell fates.

Am80, a retinoic acid receptor agonist, ameliorates murine vasculitis through the suppression of neutrophil migration and activation

Vasculitis is characterized by leukocyte infiltration in the vessel walls, with destructive damage to mural structures. Retinoids are compounds that bind to retinoic acid receptors and exert biologic activities similar to those of vitamin A, including modulatory effects on cell proliferation and differentiation. This study was undertaken to examine the therapeutic effects of a synthetic retinoid, Am80, in a murine model of vasculitis induced by Candida albicans water-soluble fraction (CAWS). Vasculitis was induced in BALB/c mice by intraperitoneal injection of CAWS. Neutrophils were depleted by injection of antineutrophil antibody-positive serum. Am80 was administered orally once daily. Vasculitis was evaluated histologically. Migration of labeled adoptively transferred cells was quantified. Chemotaxis was assessed by cell mobility analysis. Production of reactive oxygen species (ROS) and phosphorylation of MAPKs were measured by flow cytometry. Concentrations of elastase were measured by enzyme-linked immunosorbent assay. Administration of CAWS induced vasculitis in the coronary arteries and aortic root, with abundant neutrophil infiltration. Depletion of neutrophils reduced CAWS-induced vasculitis. Treatment with Am80 led to a significant attenuation of the vasculitis score and inhibition of the migration of transferred neutrophils into the site of vasculitis. In vitro, Am80 suppressed fMLP-induced chemotaxis of human peripheral blood neutrophils. ROS production and elastase release by stimulated neutrophils were reduced by AM80 treatment, and Am80 also inhibited phosphorylation of ERK-1/2 and p38 in neutrophils stimulated with fMLP plus lipopolysaccharide. Am80 significantly suppressed CAWS-induced vasculitis. This effect was presumably exerted via inhibition of neutrophil migration and activation.

Short contact therapy of acne with tretinoin

The most frequent side effect of topical retinoids is irritant contact dermatitis. It occurs in approximately 85% of patients; the percentage can reach up to 95% in patients treated with tretinoin. Severity of this dermatitis is moderate to severe in approximately 20% of patients. However, 15% of patients stop the treatment with tretinoin because of skin irritation. The authors used tretinoin as short contact therapy (SCT) in mild to moderate acne, in order to try to reduce the incidence and severity of irritant contact dermatitis. They present the final results of a sponsor-free, pilot, open, multicenter study. Seventy-four patients were treated with 0.05% tretinoin cream. It was applied once daily for 30 min. Treatment duration ranged from 8 to 32 weeks (mean duration: 12 weeks). Acne severity and treatment efficacy were evaluated by means of the Global Acne Grading System. A significant clinical improvement (≥50% from baseline) was observed in 41 patients (55.4%). Thirteen patients (17.6%) developed a mild skin irritation. Four patients (5.4%) stopped the treatment because of severe skin irritation. Efficacy of tretinoin used as SCT seems to be superimposable to that of tretinoin used according to standard modality. Tolerability of SCT with tretinoin is very good. This tolerability allows a high adherence of patients to the treatment and it markedly improves compliance.

Transcriptional effects of inhibiting epidermal growth factor receptor in keratinocytes

Epidermal growth factor receptor (EGFR) activation is important in human epithelial malignancies, including cutaneous squamous cell carcinoma, lung, colon, pancreatic, and other cancers. Therapies targeting EGFR are currently used to treat such cancers, but one significant drawback to EGFR inhibitor therapies is the associated skin toxicity. This toxicity usually presents as papular or pustular folliculitis, dry skin with pruritus and hair and nail abnormalities. The side effects often limit the usefulness of EGFR inhibitors in cancer treatment. The transcriptional changes caused by EGFR inhibition in epidermal keratinocytes have not been extensively explored. To define the transcriptional changes caused by inhibition of EGFR in primary human epidermal keratinocytes, these cells were treated with Tyrphostin AG1478 and treated and control cultures were compared in parallel, using Affymetrix microarrays. Using meta-analysis approaches, the observed changes were integrated with a large set of already existing data on transcriptional profiling in epidermal keratinocytes. We found that at the early time points, 1 hour and 4 hours after addition, AG1478 suppresses expression of genes associated with keratinocyte proliferation, attachment and motility. Apoptosis is facilitated by both induction of proapoptotic and suppression of antiapoptotic genes. Angiogenesis signals are suppressed as well. At late time points, 24 hours and 48 hours, EGFR inhibition induces mitochondrial activity and suppresses splicing and protein trafficking. Certain transcriptional effects of EGFR inhibition go against the transcriptional effects of retinoids. Surprisingly, at 48 hours, EGFR inhibition induces expression of markers of epidermal differentiation. Our results define the role of EGF receptor in human keratinocytes and the consequences of its inhibition.