Cutaneous Rosai-Dorfman disease: a systematic review and reappraisal of its treatment and prognosis.

Cutaneous Rosai Dorfman disease (CRDD) is a rare histiocytic disorder that shows distinctive clinical presentation and prognosis. Sufficient data is currently lacking regarding evidence-based management of CRDD. This systematic review aims to provide a comprehensive overview of CRDD, focusing on treatment approaches and outcomes. PubMed and Scopus databases were searched for studies on CRDD from June 1st, 2013 to May 31st, 2023. Articles describing cases of CRDD confirmed with histological examination were eligible for inclusion. All interventions for CRDD were analyzed. The primary outcome measure was the response of cutaneous lesions to treatment including complete response (CR), partial response (PR), and no response. The secondary outcome measures were mortality rate, relapse rate, and the occurrence of adverse events related to CRDD treatment. Eighty-seven articles describing 118 CRDD cases were included. The mean age was 48.2±16.8 years. The sex ratio (F/M) was 1.53. Nodular (46.6%) erythematous (45.3%) lesions, located on the face (38.1%) were the most prevalent presentations. Associated hematological malignancies were noted in 8 (6.8%) cases. Surgical excision was the most prevalent intervention (51 cases) with CR in 48 cases. Systemic corticosteroids were used in 32 cases with 20 CR/PR, retinoids in 10 cases with 4 CR/PR, thalidomide in 9 cases with 5 CR/PR, methotrexate in 8 cases with 7 CR/PR while observation was decided in 10 cases with 6 CR/PR. Factors independently associated with the absence of response to treatment were facial involvement (OR = 0.76, p = 0.014), and cutaneous lesion size (OR = 1.016, p = 0.03). This systematic review shows distinctive clinical characteristics of CRDD and provides insights into the appropriate management of the disease. It allowed a proposal of a treatment algorithm that should be interpreted in the context of current evidence and would help practitioners in treating this rare disease.

Unmet Needs in Darier's Disease from a Patient's Perspective: Lessons Learnt from the German Registry.

The MDHHgermany registry was initiated to characterize the "real-life" situation of affected individuals with Darier's disease (DD; Morbus Darier, MD) and Hailey-Hailey disease (HH), including their treatment and healthcare. To gain deeper insights into medical care of patients with DD, various aspects such as demographics, subjective symptoms, patient satisfaction with medical care, past and current therapies were explored. Patients with diagnosed DD were included. Subjective symptoms such as itch, pain and burning sensation were assessed. Individual therapy goals were recorded and patients assessed previous/current therapies along with satisfaction of medical care and treatment. A total of 55 patients were recruited; 47 patients were eligible for the analysis. Pruritus was rated the most bothersome symptom. Some 42.6% had not received systemic treatment so far or systemic therapies were rated ineffective (32.6%). Most commonly oral retinoids were prescribed, followed by corticosteroids. Patient satisfaction with medical care and treatment proved to be mediocre. This "real-life" data show an alarming unmet need regarding patients' satisfaction with medical care and treatment, evidenced by the reported lack of disease control. Further studies and interventions are needed to improve the spectrum of available therapies. MDHHgermany provides a foundational platform for future clinical trials, epidemiological studies, and pathophysiological analyses.

Common Skin Conditions in Children and Adolescents: Acne.

Acne is a chronic, recurrent inflammatory condition of the pilosebaceous unit. It affects approximately 85% of adolescents and creates significant psychosocial and financial burdens. The pathogenesis involves altered follicular growth and differentiation, microbial colonization with Cutibacterium acnes, increased sebum production influenced by androgen levels, and inflammation. Evidence-based risk factors include family history and body mass index. Diagnosis of acne is clinical, according to patient age and acne morphology and severity. Setting treatment expectations is an important aspect of management. For mild acne, benzoyl peroxide is an effective first-line drug as monotherapy or in combination with a topical retinoid and/or topical antibiotic. Oral tetracyclines are first-line drugs as part of a multipart treatment regimen for moderate to severe acne for patients older than 8 years. Oral isotretinoin is the first-line drug for moderate to severe inflammatory acne. Because of its teratogenic effects, its prescribing is monitored through the iPLEDGE Risk Evaluation and Mitigation Strategy (REMS) program. Prescribing oral or topical antibiotics as monotherapy for acne is not recommended, as this may increase microbial resistance. Combined oral contraceptives and spironolactone are used as adjunctive therapies in female adolescents. Patients with skin of color, pregnant patients, and transgender or gender diverse patients warrant special considerations in acne management.

Milia en plaque on the shoulder as an early manifestations of mycosis fungoides.

Milia en plaque (MEP) is an uncommon skin condition identified as retroauricular confluent milium by Boulzer and Fouqet in 1903 [1]. It can be mistaken for other dermatoses like Favre-Racouchot nodular elastosis, steatocystoma multiplex, and nevus comedonicus. Milia en plaque can either be primary or secondary and is typically benign, often triggered by dermatological procedures like cryotherapy, as reported in this journal. In some cases, MEP can arise as a secondary manifestation of other diseases, including folliculotropic mycosis fungoides (FMF). Despite this association, there are few documented cases in the literature. Herein, we present a patient in whom MEP served as the initial clinical presentation of FMF; the treatment involved oral retinoids and phototherapy. Furthermore, we highlight distinctive features of both conditions. It is important to emphasize that early diagnosis and treatment of FMF are vital for the patient's quality of life. The presence of MEP can serve as a valuable indicator for identifying it.

Exploring Acne Treatments: From Pathophysiological Mechanisms to Emerging Therapies.

Acne vulgaris is a common dermatological condition that can present across different ages but predominantly affects adolescents and young adults. Characterized by various lesion types, the pathogenesis of acne is complex, involving genetic, hormonal, microbial, and inflammatory factors. This review comprehensively addresses current and emerging acne management strategies, emphasizing both topical and systemic treatments, procedural therapies, and dietary modifications. Key topical agents include retinoids, benzoyl peroxide, antibiotics, and other specialized compounds. Systemic options like antibiotics, hormonal therapies, and retinoids offer significant therapeutic benefits, particularly for moderate to severe cases. Procedural treatments such as laser devices, photodynamic therapy, chemical peels, and intralesional injections present viable alternatives for reducing acne symptoms and scarring. Emerging therapies focus on novel biologics, bacteriophages, probiotics, and peptides, providing promising future options. This review underscores the importance of personalized approaches to treatment due to the multifaceted nature of acne, highlighting the potential of innovative therapies for improving patient outcomes.

Spectral and mass characterization of kinetic conversion from retinoids to retinoic acid in an in vitro 3-D human skin equivalent model.

To investigate the effect of retinoids, such as retinol (ROL), retinal (RAL), and retinyl palmitate (RP), on epidermal integrity, skin deposition, and bioconversion to retinoic acid (RA). 3-D human skin equivalent model (EpiDermFT™) was used. Epidermal cellular integrity measured by TEER values was significantly higher for a topical treatment of ROL and RAL than RP (p < 0.05). The skin deposition (µM) of ROL and RAL was approximately 269.54 ± 73.94 and 211.35 ± 20.96, respectively, greater than that of RP (63.70 ± 37.97) over 2 h incubation. Spectral changes were revealed that the CO maximum absorbance occurred between 1600∼1800 cm-1 and was greater from ROL than that from RAL and RP, indicating conjugation of R-OH to R-CHO or R-COOH could strongly occur after ROL treatment. Subsequently, a metabolite from the bioconversion of ROL and RAL was identified as RA, which has a product ion of m/z 283.06, by using liquid a chromatography-mass spectrometry (LC-MS) - total ion chromatogram (TIC). The amount of bioconversion from ROL and RAL to RA in artificial skin was 0.68 ± 0.13 and 0.70 ± 0.10 µM at 2 h and 0.60 ± 0.04 and 0.57 ± 0.06 µM at 24 h, respectively. RA was not detected in the skin and the receiver compartment after RP treatment. ROL could be a useful dermatological ingredient to maintain epidermal integrity more effectively, more stably deposit on the skin, and more steadily metabolize to RA than other retinoids such as RAL and RP.

Retinoid Synthesis Regulation by Retinal Cells in Health and Disease.

Vision starts in retinal photoreceptors when specialized proteins (opsins) sense photons via their covalently bonded vitamin A derivative 11cis retinaldehyde (11cis-RAL). The reaction of non-enzymatic aldehydes with amino groups lacks specificity, and the reaction products may trigger cell damage. However, the reduced synthesis of 11cis-RAL results in photoreceptor demise and suggests the need for careful control over 11cis-RAL handling by retinal cells. This perspective focuses on retinoid(s) synthesis, their control in the adult retina, and their role during retina development. It also explores the potential importance of 9cis vitamin A derivatives in regulating retinoid synthesis and their impact on photoreceptor development and survival. Additionally, recent advancements suggesting the pivotal nature of retinoid synthesis regulation for cone cell viability are discussed.

Synergistic effect of chitosan and ß-carotene in inhibiting MNU-induced retinitis pigmentosa.

In this study, N-Methyl-N-nitrosourea (MNU) was intraperitoneally injected to construct a mouse retinitis pigmentosa (RP) model to evaluate the protective effect of chitosan and ß-carotene on RP. The results demonstrated that chitosan synergized with ß-carotene significantly reduced retinal histopathological structural damage in RP mice. The co-treatment group of ß-carotene and chitosan restored the retinal thickness and outer nuclear layer thickness better than the group treated with the two alone, and the thickness reached the normal level. The content of ß-carotene and retinoids in the liver of chitosan and ß-carotene co-treated group increased by 46.75 % and 20.69 %, respectively, compared to the ß-carotene group. Chitosan and ß-carotene supplement suppressed the expressions of Bax, Calpain2, Caspase3, NF-κB, TNF-α, IL-6, and IL-1ß, and promoted the up-regulation of Bcl2. Chitosan and ß-carotene interventions remarkably contributed to the content of SCFAs and enhanced the abundance of Ruminococcaceae, Rikenellaceae, Odoribacteraceae and Helicobacteraceae. Correlation analysis demonstrated a strong association between gut microbiota and improvement in retinitis pigmentosa. This study will provide a reference for the study of the gut-eye axis.

A review of the topical management of acne and its associated sequelae in the Asia-Pacific region with a spotlight on trifarotene.

Acne, a highly prevalent skin disease, can be particularly bothersome for patients of Asian background because of its impact on self-confidence and social interactions. In addition to active acne lesions, some patients may develop sequelae such as scarring, macular/postinflammatory hyperpigmentation, or erythema. The tendency of Asian skin to develop sequelae because of its increased susceptibility to irritation, cultural preferences for lighter skin phototypes, and differences in skincare regimens may all contribute to the increased burden of acne. Moreover, many Asia-Pacific countries do not have their own guidelines for acne management, and those that do often have no schedule in place for regular updates. In this article, we provide a critical review of the published guidance for the management of acne and its sequelae in the Asia-Pacific region, identifying gaps in current recommendations that could be addressed to enhance standards of acne care in Asia-Pacific countries. Along with highlighting the importance of a comprehensive skincare regimen to increase treatment efficacy and adherence, we discuss topical retinoids and retinoid combination options in the acne armamentarium that may be beneficial for sequelae prevention and management, such as adapalene 0.3% ± benzoyl peroxide 2.5%, tretinoin 0.05%, tazarotene 0.1%, and trifarotene 0.005%. In particular, trifarotene 0.005% has been observed to significantly reduce acne scar counts in a Phase 4 study. The recent data highlight the need to establish up-to-date guidance for acne and acne sequelae management in Asia-Pacific countries to provide optimal care to Asian patients.

IRX4204 Induces Senescence and Cell Death in HER2-positive Breast Cancer and Synergizes with Anti-HER2 Therapy.

PURPOSE: Rexinoids, agonists of nuclear retinoid X receptor (RXR), have been used for the treatment of cancers and are well tolerated in both animals and humans. However, the usefulness of rexinoids in treatment of breast cancer remains unknown. This study examines the efficacy of IRX4204, a highly specific rexinoid, in breast cancer cell lines and preclinical models to identify a biomarker for response and potential mechanism of action. EXPERIMENTAL DESIGN: IRX4204 effects on breast cancer cell growth and viability were determined using cell lines, syngeneic mouse models, and primary patient-derived xenograft (PDX) tumors. In vitro assays of cell cycle, apoptosis, senescence, and lipid metabolism were used to uncover a potential mechanism of action. Standard anti-HER2 therapies were screened in combination with IRX4204 on a panel of breast cancer cell lines to determine drug synergy. RESULTS: IRX4204 significantly inhibits the growth of HER2-positive breast cancer cell lines, including trastuzumab and lapatinib-resistant JIMT-1 and HCC1954. Treatment with IRX4204 reduced tumor growth rate in the MMTV-ErbB2 mouse and HER2-positive PDX model by 49% and 44%, respectively. Mechanistic studies revealed IRX4204 modulates lipid metabolism and induces senescence of HER2-positive cells. In addition, IRX4204 demonstrates additivity and synergy with HER2-targeted mAbs, tyrosine kinase inhibitors, and antibody-drug conjugates. CONCLUSIONS: These findings identify HER2 as a biomarker for IRX4204 treatment response and demonstrate a novel use of RXR agonists to synergize with current anti-HER2 therapies. Furthermore, our results suggest that RXR agonists can be useful for the treatment of anti-HER2 resistant and metastatic HER2-positive breast cancer.

Importance of treating acne sequelae in skin of color: 6-month phase IV study of trifarotene with an appropriate skincare routine including UV protection in acne-induced post-inflammatory hyperpigmentation.

BACKGROUND: Acne-induced hyperpigmentation (AIH) may accompany acne vulgaris (AV) inflammation in all skin phototypes. Trifarotene has shown depigmenting properties in vivo. This study evaluated trifarotene plus skincare because it is increasingly recognized that holistic AV management should include skincare and treatments. METHODS: This is a phase IV double-blind, parallel-group study of patients (13-35 years) with moderate AV and AIH treated with trifarotene (N = 60) or vehicle (N = 63) plus skincare regimen (moisturizer, cleanser, and sunscreen) for 24 weeks. Assessments included the AIH overall disease severity (ODS) score, post-AV hyperpigmentation index (PAHPI), exit interviews, photography, and acne assessments. Standard safety assessments were included. RESULTS: Trifarotene 50 µg/g cream improved significantly from baseline in ODS score versus vehicle (-1.6 vs. -1.1, P = 0.03) at Week 12, but scores were comparable between groups at Week 24 (primary endpoint). Trifarotene had a better reduction in PAHPI score at Week 24 (-18.9% vs. -11.3% vehicle, P < 0.01). Lesion count reductions were higher with trifarotene at Week 12 versus vehicle (P < 0.001) and at Week 24 (P < 0.05), as were IGA success rates versus vehicle at Weeks 12 (P < 0.05) and 24 (P < 0.05). Patients agreed that the skincare regimen contributed to less irritation, making treatment adherence easier. Photography showed improvements in pigmentation and erythema across all skin types. AEs were more common in the vehicle group versus trifarotene (30.2 vs. 16.7%, respectively). CONCLUSIONS: In all skin phototypes, there was more rapid improvement in the ODS and PAHPI scores with trifarotene by Weeks 12 and 24, respectively. The combination of trifarotene and skincare correlated with high patient satisfaction and adherence to the treatment protocol.

Efficacy and Tolerability of Topical 0.1% Stabilized Bioactive Retinol for Photoaging: A Vehicle-Controlled Integrated Analysis.

INTRODUCTION: Chronic exposure to ultraviolet light photoages skin. Retinol, a precursor molecule to retinoic acid that causes less irritation, is available as a nonprescription, cosmetic retinoid and improves collagen production, skin elasticity, and signs of photoaging. Advances in formulation science have allowed the production of stabilized bioactive retinol formulations. This integrated analysis aims to build on previous studies and further examine the comprehensive efficacy and tolerability of topical 0.1% stabilized bioactive retinol. METHODS: This analysis included 6 vehicle-controlled studies of 0.1% stabilized bioactive retinol in women with mild-to-moderate signs of photodamage. Across all studies, the same dermatologist investigator assessed overall photodamage; wrinkles on the forehead, cheeks, and undereye area; crow’s feet wrinkles and fine lines; lack of even skin tone; and brown spots at baseline and weeks 4, 8, and 12 on a numerical scale. Tolerability was also assessed. RESULTS: Participants (retinol, N=237; vehicle, N=234) had a mean (SD) age of 47.4 (6.6) years. Retinol induced greater improvements from baseline in all signs of photoaging vs vehicle as early as week 4 and through 12 weeks of application. Few participants experienced irritation; all events were mild to moderate and transient. The most common signs of irritation were erythema (n=2) and skin scaling/peeling (n=5). CONCLUSIONS: This pooled analysis of 6 vehicle-controlled clinical studies provides new evidence for the efficacy of 0.1% stabilized bioactive retinol in improving signs of photoaging without causing major irritation. Topical 0.1% stabilized bioactive retinol was well tolerated with only a few reported cases of skin irritation. J Drugs Dermatol. 2024;23(4):     doi:10.36849/JDD.8124.

[Clinical, therapeutic and pathophysiological aspects of Darier's disease]. / Aspects physiopathologiques cliniques et thérapeutiques de la maladie de Darier.

Darier Disease is a rare autosomal dominant inherited skin disorder classified as an acantholytic dermatosis. It manifests around puberty as brownish keratotic papules of skin folds and seborrheic areas, associated with onychopathy and mucosal involvementand have a chronic relapsing-remitting course with frequent exacerbations triggered by sun exposure, heat, friction, or infections. Darier patients have an increased risk of neuropsychiatric disorders, type 1 diabetes and heart failure. Short-term management relies on antibiotics/antiviral, topical corticosteroids and/or retinoids. Moisturizers, sun protection and avoiding triggers are essential for long-term management. Conventional long-term treatment is not standardized and many topical treatments, physical and surgical measures and systemic treatments are described in the literature.

La maladie de Darier est une génodermatose rare à transmission autosomique dominante. Elle se manifeste autour de la puberté par des papules kératosiques brunâtres des plis et des zones séborrhéiques, associées à une onychopathie et une atteinte muqueuse, et évolue par poussées déclenchées par les UV, la chaleur, les frottements ou les infections. Les patients atteints présentent un risque accru de diabète de type 1, d'insuffisance cardiaque et de troubles neuropsychiatriques. La prise en charge à court terme consiste en des antibiotiques/antiviraux, des corticostéroïdes topiques et/ou des rétinoïdes. Celle à long terme repose sur les émollients et l'éviction des facteurs déclenchants. Le traitement à long terme n'étant pas codifié, de nombreux traitements locaux et sytémiques, mesures physiques et chirurgicales sont décrits dans la littérature.

Human Clinical Trials Using Topical Bakuchiol Formulations for the Treatment of Skin Disorders: A Systematic Review.

BACKGROUND: Bakuchiol is a topical cosmeceutical marketed as a retinoid alternative. Human clinical trial data on bakuchiol’s efficacy for the treatment of dermatologic conditions has not been thoroughly evaluated. OBJECTIVE: To review human clinical trials using topical formulations containing bakuchiol in the treatment of facial skin disorders. MATERIALS AND METHODS: A comprehensive electronic search of Cochrane Library, PubMed, EMBASE, and Web of Science was conducted on August 28, 2022, using the search terms “bakuchiol” and “UP256.” Study characteristics, measured outcomes, significant results, and stated limitations were extracted.  Results: Fifteen human clinical trials were analyzed. Dermatologic conditions treated included aging, acne, and post-inflammatory hyperpigmentation. Twelve trials were unblinded, open-label trials without a control group. Ten trials used a combination therapy containing bakuchiol. Four trials did not specify the dose or concentration of bakuchiol in treatment regimens. The heterogeneity of treatments, study designs, and measured outcomes makes meta-analysis unfeasible.  Conclusion: Trials lack methodologic rigor, which introduces a high risk of bias in reported outcomes. The use of combination topical formulations containing bakuchiol limits the comparison of bakuchiol’s efficacy with retinoids. Continued research with an improved trial design is needed.J Drugs Dermatol. 2024;23(4): doi:10.36849/JDD.7763.

Silica Microparticles from Sugarcane By-Products as an Encapsulation System for Retinoids Aimed at Topical Sustained Release.

The encapsulation of retinol within silica microparticles has emerged as a promising opportunity in the realm of cosmetic and pharmaceutical formulations, driven by the need to reinforce the photoprotection and oxidation stability of retinol. This work examines the process of encapsulating retinol into silica microparticles. The association efficiency, microparticle size, molecular structure, morphology, oxidation, and release profile, as well as biocompatibility and skin sensitization, were evaluated. Results showed that 0.03% of retinol and 9% of emulsifier leads to an association efficiency higher than 99% and a particle size with an average of 5.2 µm. FTIR results indicate that there is an association of retinol with the silica microparticles, and some may be on the surface. Microscopy indicates that when association happens, there is less aggregation of the particles. Oxidation occurs in two different phases, the first related to the retinol on the surface and the second to the associated retinol. In addition, a burst release of up to 3 h (30% free retinol, 17% associated retinol) was observed, as well as a sustained release of 44% of retinol up to 24 h. Encapsulation allowed an increase in the minimal skin cytotoxic concentrations of retinol from 0.04 µg/mL to 1.25 mg/mL without skin sensitization. Overall, retinol is protected when associated with silica microparticles, being safe to use in cosmetics and dermatology.

Treatment of plaque-psoriasis in HIV-positive patients.

Psoriasis is a chronic inflammatory disease that can often accompany human immunodeficiency virus (HIV) epidemics. Development of psoriasis in HIV patients is correlated with a decrease in CD4+ count. Significant variability in the clinical presentation of psoriasis makes it a challenging disease to diagnose. Furthermore, associated immunodeficiency complicates standard treatment with immunosuppressive and biological therapy. Articles that match the terms psoriasis and HIV were searched in MEDLINE and Embase and selected based on their relevance. Highly active antiretroviral therapy (HAART) is a medication regimen used to manage and treat HIV infection. In treating mild psoriasis in HIV-positive patients, topical agents combined with HAART are considered first-line therapy, followed by phototherapy. Second-line therapy includes oral retinoids, alone or combined. In treating challenging cases, apremilast has been used due to its lack of immunosuppressive effect. In case of progressive and refractory disease, limited data from studies suggest that immunosuppressive or biological therapy may be effective. Treatment of psoriasis in HIV patients remains a challenge, which is largely attributable to its complicated etiopathology and lack of an approved therapy option. In treating severe psoriasis, close collaboration with an infectious disease specialist is highly recommended. Further research is needed, preferably with an aim toward developing individualized therapy.

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.

Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function.

Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (APOB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic depletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor-associated cholesterol deposits, and photoreceptor cell death, and loss of rod but not cone function. RPE-specific reduction in Mttp had no significant effect on plasma lipids and lipoproteins. While APOB was decreased in the RPE, most ocular retinoids remained unchanged, with the exception of the storage form of retinoid, retinyl ester. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but is not directly involved in plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.