Emerging topical drug delivery approaches for the treatment of Atopic dermatitis

High mobility group box 1 cytokine targeted topical delivery of resveratrol embedded nanoemulgel for the management of atopic dermatitis

Resveratrol is a polyphenolic compound showing anti-inflammatory activity by inhibition of high mobility group box 1 cytokine responsible for the activation of nuclear factor-κB pathway in atopic dermatitis. To evaluate the efficacy of resveratrol through topical route we have developed resveratrol-loaded nanoemulgel for the effective management of atopic dermatitis in mice model. The resveratrol-loaded nanoemulsion (0.5%, 0.75% and 1% w/w) was optimized by spontaneous nano-emulsification. The optimized resveratrol-loaded nanoemulsions showed average globule size in the 180-230 nm range and found to be monodispersed. The resveratrol nanoemulgel was prepared with a SEPINEO™ P 600 gel base and propylene glycol. Ex vivo permeation and retention study resulted in significantly higher skin retention of resveratrol from resveratrol-loaded nanoemulgel than free resveratrol-loaded gel. Preclinical efficacy of resveratrol nanoemulgel displayed promising therapeutic outcomes where, western blotting of skin tissues disclosed a significant reduction in the relative expression of high mobility group box 1, the receptor for advanced glycation end products, toll-like receptor-4 and phosphorylated nuclear factor-κB. Further, real-time polymerase chain reaction also disclosed a significant reduction in pro-inflammatory cytokines such as thymic stromal lymphopoietin, interleukin-4, interleukin-13, interleukin-31, tumor necrosis factor-α and interleukin-6. The histopathological examination of skin sections showed improvement in the skin condition. Collectively, the findings from our study showcased the significant improvement in the atopic dermatitis skin condition in mice model after topical application of resveratrol loaded nanoemulgel.

Filaggrin and beyond: New insights into the skin barrier in atopic dermatitis and allergic diseases, from genetics to therapeutic perspectives

Atopic dermatitis (AD) is the most common inflammatory skin disease worldwide, affecting 20% of children and 5% of adults. One critical component in the pathophysiology of AD is the epidermal skin barrier, with its outermost layer, the stratum corneum (SC), conferring biochemical properties that enable resilience against environmental threats and maintain homeostasis. The skin barrier may be conceptualized as a key facilitator of complex interactions between genetics, host immunity, the cutaneous microbiome, and environmental exposures. The key genetic risk factor for AD development and persistence is a loss-of-function mutation in FLG, with recent advances in genomics focusing on rare variant discovery, establishment of pathogenic mechanisms, and exploration of the role of other epidermal differentiation complex gene variants in AD. Aberrant type 2 inflammatory responses down-regulate the transcription of key epidermal barrier genes, alter the composition of SC lipids, and induce further injury through a neurocutaneous feedback loop and the itch-scratch cycle. The dysbiotic epidermis exhibits reduced bacterial diversity and enhanced colonization with Staphylococcus and Malassezia species, which contribute to both direct barrier injury through the action of bacterial toxins and perpetuation of the inflammatory cascades. Enhanced understanding of each of the pathogenic mechanisms underpinning barrier disruption has led to the development of novel topical and systemic molecules, including interleukin (IL)-4Ra, IL-13, PDE4, and Janus-associated kinase inhibitors, whose clinical effectiveness exceeds conventional treatment modalities. In this narrative review, we aim to summarize the current understanding of the above-mentioned pathophysiological and therapeutic mechanisms, with a focus on the genetic, cellular, and molecular mechanisms underpinning AD development.

Exosomes derived from human dermal fibroblasts (HDFn-Ex) alleviate DNCB-induced atopic dermatitis (AD) via PPARα

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Skin barrier dysfunction is the initial step in the development of AD. Recently, exosomes have been considered as potential cell-free medicine for skin defects such as aging, psoriasis and wounds. The aim of this study was to investigate the effects of human dermal fibroblast-neonatal-derived exosome (HDFn-Ex) on AD. HDFn-Ex increased the expression of peroxisome proliferator activated receptor α (PPARα) and alleviated the 1-chloro-2,4-dinitrobenzene (DNCB)-mediated downregulation of filaggrin, involucrin, loricrin, hyaluronic acid synthase 1 (HAS1) and HAS2 in human keratinocyte HaCaT cells. However, these effects were inhibited by the PPARα antagonist GW6471. In the artificial skin model, HDFn-Ex significantly inhibited DNCB-induced epidermal hyperplasia and the decrease in filaggrin and HAS1 levels via a PPARα. In the DNCB-induced AD-like mouse model, HDFn-Ex administration reduced epidermis thickening and mast cell infiltration into the dermis compared to DNCB treatment. Moreover, the decreases in PPARα, filaggrin and HAS1 expression, as well as the increases in IgE and IL4 levels induced by DNCB treatment were reversed by HDFn-Ex. These effects were blocked by pre-treatment with GW6471. Furthermore, HDFn-Ex exhibited an anti-inflammatory effect by inhibiting the DNCB-induced increases in IκBα phosphorylation and TNF-α expression. Collectively, HDFn-Ex exhibited a protective effect on AD. Notably, these effects were regulated by PPARα. Based on our results, we suggest that HDFn-Ex is a potential candidate for treating AD by recovering skin barrier dysfunction and exhibiting anti-inflammatory activity.

Characterization of a human lesioned-skin model to assess the influence of skin integrity on drug permeability

The stratum corneum (SC) is the skin's outermost layer, organized by clusters of corneocytes among a lipid matrix, acting as a barrier. This "brick and mortar" organization is modified in many skin diseases. We proposed a lesioned-skin model for assessing the permeability of topical formulations and the impact of skin integrity on the permeability of molecules. We anticipate that removal of the SC compromises the skin barrier function, making it more permeable, affecting the biopharmaceutics of topical formulations. By stripping with 25 strips (Corneofix®), the thickness of the SC was considerably reduced, exposing the viable epidermis. Transversal and upper views of the skin by electronic microscopy and histology confirm the removal of the SC. After, we evaluated the permeability of tacrolimus (Protopic®, 0.1 % and 0.03 %) by HPLC-UV. The non-lesioned skin presented 20-25 % of tacrolimus in the SC and no drug permeated through the skin's inner layers. Contrary, the lesioned-skin model allowed the permeation of tacrolimus to the epidermis, dermis, and also in the receptor medium. These results highlight the importance of using diseased skin tissue as opposed to normal skin when assessing the permeability of pharmaceutical formulations for local topical delivery, closely mimicking the occurred events in clinical scenario.

Nanotechnology-Based Topical Delivery of Natural Products for the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic eczematous inflammatory disease that may arise from environmental, genetic, and immunological factors. Despite the efficacy of current treatment options such as corticosteroids, such approaches are mainly focused on symptom relief and may present certain undesirable side effects. In recent years, isolated natural compounds, oils, mixtures, and/or extracts have gained scientific attention because of their high efficiency and moderate to low toxicity. Despite their promising therapeutic effects, the applicability of such natural healthcare solutions is somewhat limited by their instability, poor solubility, and low bioavailability. Therefore, novel nanoformulation-based systems have been designed to overcome these limitations, thus enhancing the therapeutic potential, by promoting the capacity of these natural drugs to properly exert their action in AD-like skin lesions. To the best of our knowledge, this is the first literature review that has focused on summarizing recent nanoformulation-based solutions loaded with natural ingredients, specifically for the management of AD. We suggest that future studies should focus on robust clinical trials that may confirm the safety and effectiveness of such natural-based nanosystems, thus paving the way for more reliable AD treatments.

Nanocomposite of chitosan/gelatin/carbon quantum dots as a biocompatible and efficient nanocarrier for improving the Curcumin delivery restrictions to treat brain cancer

Curcumin (CUR) is among the most appropriate and natural-based anticancer drugs that can be applied effectively treat different classes of cancers. However, CUR suffers from a low half-life and stability in the body, which has restricted the efficacy of its delivery applications. This study is dedicated to introducing the pH-sensitive nanocomposite of chitosan (CS)/gelatin (GE)/carbon quantum dots (CQDs) as an applicable nanocarrier for enhancing CUR half-life and its delivery restrictions. The CS/GE hydrogel was synthesized by the physical crosslinking method, which improves the biocompatibility of this hydrogel. Moreover, the water-in-oil-in-water (W/O/W) double emulsion approach is involved in fabricating the drug-loaded CS/GE/CQDs@CUR nanocomposite. Afterward, drug encapsulation (EE) and loading efficiencies (LE) have been determined. Furthermore, FTIR and XRD assessments were performed to confirm the CUR incorporation into the prepared nanocarrier and crystalline features of the nanoparticles. Then, by employing Zeta potential and dynamic light scattering (DLS) analysis, the size distribution and stability of the drug-loaded nanocomposites have been assessed, which indicated monodisperse and stable nanoparticles. Furthermore, field emission scanning electron microscopy (FE-SEM) was utilized that confirmed the homogeneous distribution of the nanoparticles with smooth and quite spherical structures. In vitro drug release pattern was studied and the kinetic analysis was performed using a curve fitting technique to determine the governing release mechanism at both acidic pH and physiological conditions. The obtained outcomes from release data revealed a controlled release behavior with a 22-hour half-life, while the EE% and EL% were acquired at 46.75 % and 87.5 %, respectively. In addition, the MTT assay has been carried out on U-87 MG cell lines to evaluate the cytotoxicity of the nanocomposite. The findings showed that the fabricated nanocomposite of CS/GE/CQDs can be assumed as a biocompatible CUR nanocarrier, while the drug-loaded nanocomposite of CS/GE/CQDs@CUR showed enhanced cytotoxicity compared to the pure CUR. Based on the obtained results, this study suggests the CS/GE/CQDs nanocomposite as a biocompatible and potential nanocarrier for ameliorating CUR delivery restrictions to treat brain cancers.

Formulation Development and In Vitro/In Vivo Characterization of Methotrexate-Loaded Nanoemulsion Gel Formulations for Enhanced Topical Delivery

Methotrexate-loaded oil-in-water nanoemulsion formulations were prepared using the high shear homogenization technique. A drug excipient study (ATR-FTIR) was carried out to investigate the compatibility between the drug, the polymers, and its admixtures. The thermal stability of the nanoemulsion formulations was evaluated by subjecting them to a heating and cooling cycle. The prepared nanoemulsion formulations (FNE1 to FNE6) were evaluated for particle size, PDI value, and entrapment efficiency (EE). They were analyzed for morphological information using transmission electron microscopy. The drug (methotrexate)-loaded nanoemulsion formulations (FNE2, FNE4, and FNE6) were then converted into nanoemulsion gel formulations by adding 1% chitosan (polymer) as a gelling agent. The nanoemulsion gel formulations (FNEG2, FNEG4, and FNEG6) were investigated for physicochemical parameters, viscosity, spreadability, extrudability, drug content, and skin irritation. Various penetration enhancers (olive oil, clove, and almond oil) were employed to examine the potency of the prepared nanoemulsion gel formulations. In vitro drug release, ex vivo permeation, skin drug retention, and stability tests were carried out for evaluation of the prepared nanoemulsion gel formulations (FNEG2, FNEG4, and FNEG6). The data obtained from the in vitro study were subjected to the kinetic model, and the Korsemeyer-Peppas model was best fitted to the data. The nanoemulsion gel formulation FNEG6 showed the maximum controlled drug release and followed an anomalous, non-Fickian release mechanism. The use of almond oil in the preparation of the nanoemulsion gel formulation FNEG6 helped the penetration of the drug across stratum corneum and the restructuring of the properties of skin and resulted in a higher penetration and retention of methotrexate in a deeper layer of the skin. The current study concluded that the methotrexate-loaded nanoemulsion gel formulation FNEG6 showed the best optimum release, permeation, and retention results as compared to the available oral tablets' formulations, followed by a low serum concentration and the maximum drug retention, which is beneficial in treating skin infections and reducing systemic toxicity.

Biologically Synthesized Rosa rugosa-Based Gold Nanoparticles Suppress Skin Inflammatory Responses via MAPK and NF-κB Signaling Pathway in TNF-α/IFN-γ-Induced HaCaT Keratinocytes

Nanotechnology-applied materials and related therapeutics have gained attention for treating inflammatory skin diseases. The beach rose (Rosa rugosa), belonging to the family Rosaceae, is a perennial, deciduous woody shrub endemic to northeastern Asia. In this study, R. rugosa-based gold nanoparticles (RR-AuNPs) were biologically synthesized under optimal conditions to explore their potential as anti-inflammatory agents for treating skin inflammation. The synthesized RR-AuNPs were analyzed using field emission-transmission electron microscopy, energy-dispersive X-ray spectrometry, selected-area electron diffraction, and X-ray diffraction. The uniformly well-structured AuNPs showed near-spherical and polygonal shapes. Cell viability evaluation and optical observation results showed that the RR-AuNPs were absorbed by human keratinocytes without causing cytotoxic effects. The effects of RR-AuNPs on the skin inflammatory response were investigated in human keratinocytes treated with tumor necrosis factor-α/interferon-γ (T + I). The results showed that T + I-stimulated increases in inflammatory mediators, including chemokines, interleukins, and reactive oxygen species, were significantly suppressed by RR-AuNP treatment in a concentration-dependent manner. The western blotting results indicated that the RR-AuNP-mediated anti-inflammatory effects were highly associated with the suppression of inflammatory signaling, mitogen-activated protein kinase, and nuclear factor-κB. These results demonstrate that plant extract-based AuNPs are novel anti-inflammatory candidates for topical application to treat skin inflammation.