The development of atopic dermatitis (AD) in infancy, and subsequent allergic rhinitis, food allergies, and asthma in later childhood, is known as the atopic march. The mechanism is largely unknown, yet the course of disease indicates the contribution of inter-epithelial crosstalk, through to the onset of inflammation in the skin and progression to another mucosal epithelium. Here, we investigated if and how skin-lung epithelial crosstalk could contribute to the development of the atopic march. First, we emulated this inter-epithelial crosstalk through indirect co-culture of bio-engineered atopic-like skin disease models and three-dimensional bronchial epithelial models trig-gering an asthma-like phenotype in the latter. A subsequent secretome analysis identified thrombos-pondin-1, CD44, complement factor C3, fibronectin, and syndecan-4 as potentially relevant skin-derived mediators. As these mediators are extracellular matrix (ECM)-related proteins, we then stud-ied the involvement of the ECM, unveiling distinct proteomic, transcriptomic, and ultrastructural dif-ferences in atopic samples. The latter indicated ECM remodeling triggering the release of the above-mentioned mediators. In addition to pro-inflammatory effects in lung tissue, the ECM mediators also exert distinct effects on CD4+ T cells. In vivo mouse data showed that exposure to these mediators over seven days dysregulated activated circadian clock genes which have been previously dis-cussed in the context of atopic diseases and asthma development. We hypothesize the existence of a skin-lung axis that could contribute to the atopic march driven by skin ECM remodeling.

Patients with AD are predisposed to developing other atopic diseases such as allergic asthma, a process known as the atopic march. The pathomechanism as to how skin communicates inflammation to the lungs remains largely elusive. We studied if and how inter-epithelial crosstalk between skin and lung may contribute to the atopic march using bioengineered atopic-like skin disease and bronchial epithelial models. Co-cultivation of the tissue models triggered an asthma-like phenotype in the bronchial epithelial models characterized by epithelial hyperproliferation, hyperplasia of mucus producing cells and upregulation of asthma markers. A targeted secretome analysis revealed the ECM-associated factors thromospondin-1, CD44, fibronectin and syndecan-4 as potentially relevant skin-derived mediators. SEM analysis of healthy and atopic ECM demonstrated distinct ECM disorganization and significantly reduced collagen (p≤0.001) and elastin (p≤0.01) concentrations. Transcriptomic and proteomic profiling of atopic fibroblast-derived ECM revealed distinct ECM-remodeling pathways involved and significant upregulation of proteins associated with ECM-remodeling and inflammation including HTRA1, DDR2, and STAT1 (each p≤0.01). Ongoing studies aim to identify the causative mechanisms for the observed changes in the ECM produced by atopic fibroblasts, which could be rooted in inflammatory processes or fibroblast-keratinocyte crosstalk. In conclusion, the ECM produced by atopic fibroblasts is disturbed in structure and composition with increased ECM-remodeling, which may contribute to the progression of atopic diseases to other epithelia.

TITLE: EXTRACELLULAR MATRIX REMODELING IN ATOPIC DERMATITIS HAR1 NESSES THE ONSET OF AN ASTHMATIC PHENOTYPE AND IS A POTENTIAL CON2 TRIBUTOR TO THE ATOPIC MARCH 3 4 Authors: Patrick Graff1,10, Jenny Wilzopolski2, Anne Voss3, Travis M. Blimkie4, January Weiner 3rd 5 5, Olivia Kershaw3, Preety Panwar6, Tillie Hackett7, Dieter Brömme6, Lucie Loyal5,8, Andreas Thiel5,8, 6 Dieter Beule8, Robert E.W. Hancock4, Achim D. Gruber3, Wolfgang Bäumer2, *Sarah Hedtrich5,9,10 7 8 Affiliations: 9

Human skin equivalents emerged as novel tools in preclinical dermatological research. It is being claimed that they may bridge the translational gap between preclinical and clinical research, yet only a few studies have investigated their suitability for preclinical drug testing so far. Therefore, we investigated if inflammatory skin equivalents, which emulate hallmarks of atopic dermatitis (AD), are suitable to assess the anti-inflammatory effects of dexamethasone (DXM) in a cream formulation or loaded onto dendritic core-multishell nanoparticles. Topical DXM application resulted in significantly decreased expression of the proinflammatory cytokine TSLP, increased expression of the skin barrier protein involucrin, and facilitated glucocorticoid receptor translocation in a dose-dependent manner. Further, DXM treatment inhibited gene expression of extracellular matrix components, potentially indicative of the known skin atrophy-inducing side effects of glucocorticoids. Overall, we were able to successfully assess the anti-inflammatory effects of DXM and the superiority of the nanoparticle formulation. Nevertheless the identification of robust readout parameters proved challenging and requires careful study design.

BACKGROUND:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilises the angiotensin-converting enzyme 2 (ACE2) transmembrane peptidase as cellular entry receptor. However, whether SARS-CoV-2 in the alveolar compartment is strictly ACE2-dependent and to what extent virus-induced tissue damage and/or direct immune activation determines early pathogenesis is still elusive. METHODS:Spectral microscopy, single-cell/-nucleus RNA sequencing or ACE2 "gain-of-function" experiments were applied to infected human lung explants and adult stem cell derived human lung organoids to correlate ACE2 and related host factors with SARS-CoV-2 tropism, propagation, virulence and immune activation compared to SARS-CoV, influenza and Middle East respiratory syndrome coronavirus (MERS-CoV). Coronavirus disease 2019 (COVID-19) autopsy material was used to validate ex vivo results. RESULTS:We provide evidence that alveolar ACE2 expression must be considered scarce, thereby limiting SARS-CoV-2 propagation and virus-induced tissue damage in the human alveolus. Instead, ex vivo infected human lungs and COVID-19 autopsy samples showed that alveolar macrophages were frequently positive for SARS-CoV-2. Single-cell/-nucleus transcriptomics further revealed nonproductive virus uptake and a related inflammatory and anti-viral activation, especially in "inflammatory alveolar macrophages", comparable to those induced by SARS-CoV and MERS-CoV, but different from NL63 or influenza virus infection. CONCLUSIONS:Collectively, our findings indicate that severe lung injury in COVID-19 probably results from a macrophage-triggered immune activation rather than direct viral damage of the alveolar compartment.

Polymeric nanogels are promising nonirritating nanocarriers for topical delivery applications. However, conventional hydrophilic networks limit encapsulation of hydrophobic therapeutics and hinder tailored interactions with the amphiphilic skin barrier. To address these limitations, we present amphiphilic nanogels containing hydrophilic networks with hydrophobic domains. Two competing factors determine favorable nanogel-skin interactions and need to be balanced through network composition: suitable surface hydrophobicity and low network rigidity (through physical hydrophobic cross-links). To ensure comparability in such investigations, we prepared a library of nanogels with increasing hydrophobic cholesteryl amounts but similar colloidal features. By combining mechanical and surface hydrophobicity tests (atomic force microscopy (AFM)) with dermal delivery experiments on excised human skin, we can correlate an increased delivery efficacy of Nile red to the viable epidermis with a specific network composition, i.e., 20-30 mol % cholesterol. Thus, our nanogel library identifies a specific balance between surface amphiphilicity and network rigidity to guide developments of advanced dermal delivery vehicles.

Mucosal surfaces pose a challenging environment for efficient drug delivery. Various delivery strategies such as nanoparticles have been employed so far; yet, still yielding limited success. To address the need of efficient transmucosal drug delivery, this report presents the synthesis of novel disulfide-containing dendritic polyglycerol (dPG)-based nanogels and their preclinical testing. A bifunctional disulfide-containing linker is coupled to dPG to act as a macromolecular crosslinker for poly-N-isopropylacrylamide (PNIPAM) and poly-N-isopropylmethacrylamide (PNIPMAM) in a precipitation polymerization process. A systematic analysis of the polymerization reveals the importance of a careful polymer choice to yield mucus-degradable nanogels with diameters between 100 and 200 nm, low polydispersity, and intact disulfide linkers. Absorption studies in porcine intestinal tissue and human bronchial epithelial models demonstrate that disulfide-containing nanogels are highly efficient in overcoming mucosal barriers. The nanogels efficiently degrade and deliver the anti-inflammatory biomacromolecule etanercept into epithelial tissues yielding local anti-inflammatory effects. Over the course of this work, several problems are encountered due to a limited availability of valid test systems for mucosal drug-delivery systems. Hence, this study also emphasizes how critical a combined and multifaceted approach is for the preclinical testing of mucosal drug-delivery systems, discusses potential pitfalls, and provides suggestions for solutions.

Journal of the European Academy of Dermatology and VenereologyVolume 34, Issue 6 p. e262-e265 Letter to the Editor Fibroblasts from atopic dermatitis patients trigger inflammatory processes and hyperproliferation in human skin equivalents A. Löwa, Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorP. Graff, Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorS. Kaessmeyer, Department of Veterinary Medicine, Institute for Veterinary Anatomy, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorS. Hedtrich, Corresponding Author sarah.hedtrich@ubc.ca orcid.org/0000-0001-6770-3657 Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, CanadaCorrespondence: S. Hedtrich. E-mail: sarah.hedtrich@ubc.caSearch for more papers by this author A. Löwa, Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorP. Graff, Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorS. Kaessmeyer, Department of Veterinary Medicine, Institute for Veterinary Anatomy, Freie Universität Berlin, Berlin, GermanySearch for more papers by this authorS. Hedtrich, Corresponding Author sarah.hedtrich@ubc.ca orcid.org/0000-0001-6770-3657 Institute of Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, CanadaCorrespondence: S. Hedtrich. E-mail: sarah.hedtrich@ubc.caSearch for more papers by this author First published: 28 January 2020 https://doi.org/10.1111/jdv.16240Citations: 4Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Citing Literature Volume34, Issue6June 2020Pages e262-e265 RelatedInformation

Topical treatment of mild-to-moderate psoriasis with corticosteroids suffers from challenges that include reduced drug bioavailability at the desired site of action. The retention of therapeutics within the epidermis can safely treat skin inflammation, scaling, and erythema associated with psoriasis while avoiding possible side effects associated with systemic treatments. We successfully synthesized and characterized a pH-responsive biodegradable poly-L-glutamic acid (PGA)-fluocinolone acetonide (FLUO) conjugate that allows the controlled release of the FLUO to reduce skin inflammation. Additionally, the application of a hyaluronic acid (HA)-poly-L-glutamate cross polymer (HA-CP) vehicle boosted skin permeation. During in vitro and ex vivo analyses, we discovered that PGA-FLUO inhibited pro-inflammatory cytokine release, suggesting that polypeptidic conjugation fails to affect the anti-inflammatory activity of FLUO. Additionally, ex vivo human skin permeation studies using confocal microscopy revealed the presence of PGA-FLUO within the epidermis, but a minimal presence in the dermis, thereby reducing the likelihood of FLUO entering the systemic circulation. Finally, we demonstrated that PGA-FLUO applied within HA-CP effectively reduced psoriasis-associated phenotypes in an in vivo mouse model of human psoriasis while also lowering levels of pro-inflammatory cytokines in tissue and serum. Overall, our experimental results demonstrate that PGA-FLUO within an HA-CP penetration enhancer represents an effective topical treatment for psoriasis.

Autosomal recessive congenital ichthyosis (ARCI) disrupts normal keratinization, resulting in generalized scaling of the skin. There are presently no curative therapies available (Fleckman et al., 2013Fleckman P. Newell B.D. Van Steensel M.A. Yan A.C. Topical treatment of ichthyoses.Dermatol Ther. 2013; 26: 16-25Crossref PubMed Scopus (15) Google Scholar). Local protein replacement is, therefore, an encouraging approach for a more specific treatment. ARCI refers to a heterogeneous group of rare skin keratinization disorders with an estimated prevalence of 1 in 50,000–200,000 (Dreyfus et al., 2014Dreyfus I. Bourrat E. Maruani A. Bessis D. Chiaverini C. Vabres P. et al.Factors associated with impaired quality of life in adult patients suffering from ichthyosis.Acta Derm Venereol. 2014; 94: 344-346Crossref PubMed Scopus (23) Google Scholar). The disease is characterized by notable impairments to the skin's barrier function, resulting in frequent infections and increased transepidermal water loss. ARCI is caused by mutations in 1 of 12 identified genes involved in epidermal differentiation. The most common of these are loss of function mutations in TGM1, affecting approximately 30% of patients (Rodriguez-Pazos et al., 2009Rodriguez-Pazos L. Ginarte M. Vega A. Toribio J. Autosomal recessive congenital ichthyosis.J Invest Dermatol. 2009; 129: 1319-1321Abstract Full Text Full Text PDF PubMed Scopus (140) Google Scholar). TGM1 encodes transglutaminase 1 (TG1), a protein that plays an essential role in the formation of the cornified envelope (Eckert et al., 2005Eckert R.L. Sturniolo M.T. Broome A.M. Ruse M. Rorke E.A. Transglutaminase function in epidermis.J Invest Dermatol. 2005; 124: 481-492Abstract Full Text Full Text PDF PubMed Scopus (155) Google Scholar). Because animal models of severe keratinization disorders such as ARCI are not viable and animal skin poorly represents human skin (Gerber et al., 2014Gerber P.A. Buhren B.A. Schrumpf H. Homey B. Zlotnik A. Hevezi P. The top skin-associated genes: a comparative analysis of human and mouse skin transcriptomes.Biol Chem. 2014; 395: 577-591Crossref PubMed Scopus (62) Google Scholar), the use of organotypic skin equivalents has emerged as a valid tool to investigate ARCI. In the present study, full-thickness skin equivalents generated from the fibroblasts and keratinocytes of ARCI patients with mutations in TGM1 were treated topically with TG1. Because biomacromolecules do not normally overcome the skin barrier, owing to their high molecular weight, protein delivery was mediated by use of thermoresponsive nanogels (tNG) (Cuggino et al., 2011Cuggino J.C. Alvarez I.C.I. Strumia M.C. Welker P. Licha K. Steinhilber D. et al.Thermosensitive nanogels based on dendritic polyglycerol and N-isopropylacrylamide for biomedical applications.Soft Matter. 2011; 7: 11259-11266Crossref Scopus (67) Google Scholar). Proteins as large as 150 kDa have been encapsulated within tNGs and subsequently released above a thermal trigger point (Giulbudagian et al., 2018bGiulbudagian M. Yealland G. Hönzke S. Geisendörfer B. Kleuser B. Hedtrich S. et al.Breaking the barrier—potent anti-inflammatory activity following efficient topical delivery of etanercept using thermoresponsive nanogels.Theranostics. 2018; 8: 450-463Crossref PubMed Scopus (49) Google Scholar, Witting et al., 2015Witting M. Molina M. Obst K. Plank R. Eckl K.M. Hennies H.C. et al.Thermosensitive dendritic polyglycerol-based nanogels for cutaneous delivery of biomacromolecules.Nanomedicine. 2015; 11: 1179-1187Crossref PubMed Scopus (69) Google Scholar). Our groups previously reported the epidermal delivery of functional TG1 using topically applied tNGs and rescue of barrier defects in TGM1 knockdown skin equivalents (Witting et al., 2015Witting M. Molina M. Obst K. Plank R. Eckl K.M. Hennies H.C. et al.Thermosensitive dendritic polyglycerol-based nanogels for cutaneous delivery of biomacromolecules.Nanomedicine. 2015; 11: 1179-1187Crossref PubMed Scopus (69) Google Scholar). However, whether TG1-loaded tNGs are an effective topical treatment for ARCI skin with TGM1 mutations, rather than transiently induced TGM1 knockdowns, was still unclear. The study was approved by the Ethics Committee of the Medical University of Innsbruck, Austria, and samples were taken after obtaining written informed consent of the probands. Full-thickness skin equivalents were generated from fibroblasts plus normal keratinocytes, keratinocytes with transient TGM1 knockdowns, or keratinocytes from ARCI patients with TGM1 mutations (Figure 1). In comparison to normal equivalents, TGM1 knockdown and patient equivalents both demonstrated slightly thinned stratum corneum and epidermis, with reduced cell number within the granular layer. The epidermal differentiation markers keratin 14 and 10 were distributed appropriately. TG1 activity was present in normal skin equivalents but not in those generated from patient cells or TGM1 knockdown keratinocytes, in line with the inactivating mutations found in patient 1, and the absence of persistent TG1 expression in patient 2 and knockdown equivalents. Notably, knockdown equivalents demonstrated increasing TGM1 transcript levels over time (>50% after 10 days cultivation), indicating a loss of effective repression (Supplementary Figure S1 online). To assess their biocompatibility, TG1-loaded tNGs were incubated with normal, patient 1, and patient 2 keratinocytes, as well as fibroblasts for up to 48 hours, resulting in no significant cytotoxicity at any of the tested concentrations (Figure 1b, Supplementary Figures S2 and S3 online). Concordantly, no significant cytotoxicity was observed following the application of tNGs onto skin equivalents (Figure 1g). Additionally, the ability of TG1, alone or loaded in tNGs, to enter keratinocytes was assessed by confocal microscopy. In both cases, TG1 entered the cytoplasm in a time-dependent manner (Supplementary Figure S4 online). Notably, tNGs entered more rapidly than the TG1, which, with their lack of clear intracellular co-localization, would suggest that the tNGs and TG1 enter keratinocytes separately, concordant with the relatively quick release of protein at temperatures ≥35°C. It should be noted, however, that previous evidence indicates tNGs are largely unable to overcome the stratum corneum of even barrier-deficient skin, suggesting that, in most cases, little or no contact will occur between them and viable epidermal cells (Giulbudagian et al., 2018aGiulbudagian M. Hönzke S. Bergueiro J. Işik D. Schumacher F. Saeidpour S. et al.Enhanced topical delivery of dexamethasone by β-cyclodextrin decorated thermoresponsive nanogels.Nanoscale. 2018; 10: 469-479Crossref Google Scholar). Finally, patient 1 skin equivalents were topically treated with TG1, either in solution or loaded in tNGs, four times over 8 days. Untreated patient 1 equivalents demonstrated decreased barrier function, shown by the significant increases in their apparent permeabilities to testosterone compared to normal equivalents (Figure 2a). Following full treatment regimens with TG1-loaded tNGs, significant decreases in apparent permeabilities—indicating improved barrier function—correlating to TG1 dose were seen (Figure 2a, 2d, Supplementary Figure S5 online). Importantly, permeation was almost unaffected by the application of unloaded tNG or TG1 dissolved in phosphate buffered saline only (Figure 2b, 2c). Activity staining confirmed the delivery of functional TG1 into viable epidermal layers (Figure 2e), and the distribution of activity was comparable to normal equivalents. Improvement of barrier activity was further confirmed by permeability tests with Lucifer yellow (Figure 2f) and N-hydroxy-sulfosuccinimide-LC-biotin (Supplementary Figure S6 online). Compared to equivalents with normal keratinocytes, a 59-fold increase was seen in the amount of Lucifer yellow fully passing through patient 1 equivalents. Similarly, 39-fold and 43-fold increases were respectively seen in patient 1 equivalents treated with unloaded tNG and TG1 dissolved in phosphate buffered saline. However, following treatment with TG1-loaded tNGs, full Lucifer yellow penetration was only 1.2-fold that of the control, clearly corroborating the role of TG1-loaded tNGs in the reconstitution of patient equivalent barrier function. It is highly likely that the majority of TG1 penetrating into the viable epidermis did so independently of the tNGs because they do not overcome the stratum corneum (Giulbudagian et al., 2018aGiulbudagian M. Hönzke S. Bergueiro J. Işik D. Schumacher F. Saeidpour S. et al.Enhanced topical delivery of dexamethasone by β-cyclodextrin decorated thermoresponsive nanogels.Nanoscale. 2018; 10: 469-479Crossref Google Scholar). This study aimed to further characterize the therapeutic potential of TG1-loaded tNGs in ARCI skin, as well as to better understand their mechanism of action, based on a previous proof-of-principle study demonstrating epidermal delivery of TG1 following topical application of TG1-loaded tNGs (Witting et al., 2015Witting M. Molina M. Obst K. Plank R. Eckl K.M. Hennies H.C. et al.Thermosensitive dendritic polyglycerol-based nanogels for cutaneous delivery of biomacromolecules.Nanomedicine. 2015; 11: 1179-1187Crossref PubMed Scopus (69) Google Scholar). Overall, these data verify that topical protein substitution could mitigate or even reverse the ARCI disease phenotype. Notably, Aufenvenne et al., 2013Aufenvenne K. Larcher F. Hausser I. Duarte B. Oji V. Nikolenko H. et al.Topical enzyme-replacement therapy restores transglutaminase 1 activity and corrects architecture of transglutaminase-1-deficient skin grafts.Am J Hum Genet. 2013; 93: 620-630Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar previously demonstrated that topical applications of TG1 mixed with cationic liposomes successfully delivered the functional protein to skin equivalents, formed from TGM1 mutant ARCI patient cells, grafted onto humanized mice. In contrast to our system, no changes to barrier function were observed upon treatment, likely a result of their model; unlike the typical ARCI phenotype, the grafted animals demonstrated compact hyperkeratosis and transepidermal water loss levels close to non-ARCI controls. In summary, topical TG1 replacement therapy is a highly promising therapeutic avenue for ARCI patients with disease-causing TGM1 mutations. The work here indicates TG1 delivery to the intercellular spaces between keratinocytes, and possibly their intracellular environments, can produce therapeutic improvements to the skin-barrier function of the ARCI phenotype. It is hypothesized that increasing the concentration or enzymatic activity of TG1 within the tNG will result in improved therapeutic efficacy and is the likely starting point for future development. The ability of tNGs to encapsulate a wide variety of proteins and deliver these past the stratum corneum of barrier-deficient skin makes them a promising platform technology to treat a range of inflammatory and monogenic skin diseases. Sarah Hedtrich: http://orcid.org/0000-0001-6770-3657 Hans Christian Hennies: http://orcid.org/0000-0001-7210-2389 The authors state no conflict of interest. The authors would like to thank Katja Fuchs and Maria Molina for their scientific support, Christian Ploner for providing skin samples, and fu:stat for excellent help with the statistical analysis of the data. Funding from the German Research Foundation (HE7440/2-1) and the Berlin-Brandenburg Research Platform BB3R to SH and the German Research Foundation (HE3119/9-1), the Austrian Science Fund (FWF, I2259-B26), the German Federal Ministry for Education and Research (E-Rare-2 01GM1201), and the Cologne Fortune Program of the Faculty of Medicine, University of Cologne, to HCH is greatly acknowledged. Download .pdf (.8 MB) Help with pdf files Supplementary Data

Due to the low cutaneous bioavailability of tacrolimus (TAC), penetration enhancers are used to improve its penetration into the skin. However, poor loading capacity, non-biodegradability, toxicity, and in some cases inefficient skin penetration are challenging issues that hamper their applications for the dermal TAC delivery. Here we present poly(lactide-co-glycerol) (PLG) as a water soluble, biodegradable, and biocompatible TAC-carrier with high loading capacity (14.5% w/w for TAC) and high drug delivery efficiencies into the skin. PLG was synthesized by cationic ring-opening copolymerization of a mixture of glycidol and lactide and showed 35 nm and 300 nm average sizes in aqueous solutions before and after loading of TAC, respectively. Delivery experiments on human skin, quantified by fluorescence microscopy and LC-MS/MS, showed a high ability for PLG to deposit Nile red and TAC into the stratum corneum and viable epidermis of skin in comparison with Protopic® (0.03% w/w, TAC ointment). The cutaneous distribution profile of delivered TAC proved that 80%, 16%, and 4% of the cutaneous drug level was deposited in the stratum corneum, viable epidermis, and upper dermis, respectively. TAC delivered by PLG was able to efficiently decrease the IL-2 and TSLP expressions in human skin models. Taking advantage of the excellent physicochemical and biological properties of PLG, it can be used for efficient dermal TAC delivery and potential treatment of inflammatory skin diseases.