Skin Immunity Research Articles

MRGPRX2 signaling involves the Lysyl-tRNA synthetase and MITF pathway.

MRGPRX2, a G-protein-coupled-seven transmembrane domain receptor, is mainly expressed in mast cells and neurons and is involved in skin immunity and pain. It is implicated in the pathophysiology of non-IgE-mediated immediate hypersensitivity and has been related to adverse drug reactions. Moreover, a role has been proposed in asthma, atopic dermatitis, contact dermatitis, and chronic spontaneous urticaria. Although it has a prominent role in disease, its signaling transduction is poorly understood. This study shows that MRGPRX2 activation with substance P increased Lysyl t-RNA synthetase (LysRS) translocation to the nucleus. LysRS is a moonlighting protein with a dual role in protein translation and IgE signaling in mast cells. Upon allergen- IgE-FcεRI crosslinking, LysRS is translocated to the nucleus and activates microphthalmia-associated transcription factor (MITF) activity. In this study, we found that MRGPRX2 triggering led to MITF phosphorylation and increased MITF activity. Therefore, overexpression of LysRS increased MITF activity after MRGPRX2 activation. MITF silencing reduced MRGPRX2-dependent calcium influx and mast cell degranulation. Furthermore, a MITF pathway inhibitor, ML329, impaired MITF expression, calcium influx, and mast cell degranulation. Moreover, drugs such as atracurium, vancomycin, and morphine, reported to induce MRGPRX2-dependent degranulation, increased MITF activity. Altogether, our data show that MRGPRX2 signaling enhances MITF activity, and its abrogation by silencing or inhibition resulted in defective MRGPRX2 degranulation. We conclude that MRGPRX2 signaling involves the LysRS and MITF pathway. Thus, MITF and MITF-dependent targets may be considered therapeutic approaches to treat pathologies where MRGPRX2 is implicated.

Effects of γ-Irradiated Date (Phoenix dactylifera) Fruit on Growth, Immunological and Antioxidant Parameters of Goldfish (Carassius auratus)

The aim of this study was to evaluate the potential effects of γ-irradiated date palm fruit (Phoenix dactylifera), which is rich in phenolic acids and has important and varied biological bioactivities, on growth performance, mucosal immunity and liver antioxidant status in goldfish (Carassius auratus). The antioxidant activity, alongside the phenolic and flavonoid contents, were also determined in irradiated palm fruit extracts (IPFE). The results showed that IPFE5 had a higher antioxidant activity as well as heightened phenolic and flavonoid contents compared to IPFE10 and IPFE0. Meanwhile, goldfish specimens were randomly divided into three groups with three replicates in each. Subsequently, skin immunity and antioxidant activity in the livers of the goldfish were studied. The growth rates of fish fed with IPFE5 and IPFE10 were significantly higher (p < 0.05) compared to the CTR group. In addition, fish fed with the IPFE5 diet demonstrated increased mucosal immunity compared to the CTR group (p < 0.05). Lipid peroxidation levels as well as antioxidant enzyme activities were also higher in all the IPFE-fed groups compared to the CTR group (p < 0.05). These data showed that 40-day dietary administration of γ-irradiated date extract, especially IPFE5, improved growth performance, mucosal immunity, and liver antioxidant capacity in goldfish. The suitability of administrating this additive in the diet of farmed fish is discussed.

Androgen signaling shapes the sexual differences of skin immunity by regulating ILC2 and dendritic cells

Abstract The skin immune system mediates the skin health status, but the sex differences of the skin immune system are still unclear. This study aims to investigate sex differences in the skin immune system and decipher the underlying regulatory factors. We found that female mice have a higher magnitude of adaptive immune responses during commensal bacteria association and pathogen infection. Correspondingly, females have a higher level of skin dendritic cells (DCs), which play a fundamental role in commensal-induced adaptive immune responses. These sex differences were regulated by male sex hormones, that castration of males normalized the sex differences in the level of skin immune cells as well as the adaptive immune responses to bacteria. However, our scRNA-seq data reveals that androgen receptor is not expressed in DCs, but highly expressed in skin ILC2. Females have a significantly higher level of ILC2 than males and ILC2 from females also have a more activating gene expression signature than ILC2 from males. Females also have a significantly higher level of ILC2-produced IL-13 and GM-CSF than male mice. In addition, our data reveal that IL-13 and GM-CSF play a critical role to maintain the level of skin DCs, that IL-13/GM-CSF deficient mice have a remarkable decrease of skin DCs, and the sex differences of DCs are also largely impaired. Therefore, based on these findings, we suggest that androgen signaling negatively regulates the level of skin ILC2 and DCs, thereby shaping sex-specific skin immunity to commensals, pathogens, and/or other stimuli. Collectively our work proposes a mechanism for the heighten immunity observed in female and have important implication for our understanding of tissue immunity in the context of infection and cancer.

Skin immunity during pregnancy

Abstract Pregnancy presents a challenging immunological dilemma. The maternal immune system must tolerate fetal antigens, which implies pregnancy may induce specific mechanisms of immunoregulation. Yet within this regulatory milieu, protection against pathogens must be maintained. How does the maternal immune system navigate these opposing demands? Successfully navigating this immunological dilemma is essential for supporting the reproductive fitness of the organism, and generally, the survival of any mammalian species. Of particular importance in this context are barrier tissues, like the skin, which represent the primary portal of entry for pathogens. These barrier tissues are an especially important first line of defense during pregnancy, since adaptive immunity must be regulated to tolerate the fetal antigens which distribute throughout maternal tissues. However, little is known about how immunity in barrier tissues is altered during pregnancy. Our preliminary studies have identified an increase in ceramide levels in the skin during pregnancy. Ceramides have been shown to be critical mediators of skin barrier function, and may prevent pathogens from breaching the skin. Additionally, in the setting of S. aureus infection, pregnant skin demonstrated increased infiltration of innate immune cells, as well as an increase in type I immunity among adaptive cells. Together, these data suggest that the protective mechanisms of the skin are altered during pregnancy. Further insights in this area may elucidate an especially critical role for barrier tissue immunity in defending against infection during pregancy, and may eventually help guide improved clinical strategies to prevent and treat infections in pregnant mothers. Supported by Perelman School of Medicine's Medical Scientist Training Program and intramural research funding from NIAID.

Pellino1 promotes immunity in the skin during infection with herpes simplex virus (HSV)

Abstract Pellino1 (Peli1) is a ubiquitin ligase involved in IL-1 and Toll-like receptor signaling; however, the role of Pellino1 in skin immunity against HSV is unknown. Here, using the mouse flank HSV-1 skin infection model, we demonstrate that Pellino1 has several critical functions during active viral replication. Analyses of single cell genome wide gene expression data (RNA-seq) revealed expression of Peli1mRNA throughout the skin including in epithelial, fibroblast and immune cells. Both histology and RNA-seq demonstrated normal development of the epidermis and dermis in Pellino1 knockout (KO) mice. The median survival of Pellino1 KO mice was 12 days compared to greater than 16 days in wild type mice. Pellino1 deficient mice also developed larger zosteriform skin lesions along affected dermatomes. During infection HSV-1 did not replicate in the dermis. Immunohistochemistry revealed delayed recruitment of myeloid and T cells to early infected epidermis in Pellino1 deficient mice. This correlated with lower expression of the inflammatory IL-1 and IL-36 cytokines and the poorly understood chemokine Grp15l. In Pellino1 KO mice, the virus spread extensively through the epidermis, follicular infundibulum into sebaceous glands where sebocytes were found positive for the virus. Histological analyses for HSV-1 and neuronal axons revealed nerve endings throughout the epidermis and axons wrapped around the hair follicles. Dissemination of HSV-1 into the sebaceous glands did not appear to involve a shift in how the virus migrated through these nerve axons as early lesions were only found in the interfollicular epidermis. In conclusion, Pellino1 plays important roles in restricting viral dissemination. Supported by grant from NIH (R01 AI125111)

Host colonization with cutaneous commensal induces humoral immunity via formation of dermal tertiary lymphoid organs

Abstract The skin is one of the largest barrier sites which harbors a plethora of microorganisms. Whether skin microbiota promotes humoral responses remains unknown. Here we show that colonization with common skin commensal Staphylococcus epidermidis profoundly modulates cutaneous immunity that results in serum responsiveness with antigen-specific IgG antibodies. Such response is uncoupled from inflammatory signals and is associated with the induction of dermal tertiary lymphoid organs that closely resemble classical germinal centers. Of note, such responses occur in a tissue autonomous manner as evidenced by the preserved antibody repertoire in mice deficient in professional lymphoid organs. Our data also uncover a non-redundant role for Langerhan’s cells for the generation of commensal specific antibodies. Further, our work proposes a model by which commensal specific antigens are collected in the hair follicle leading to the generation of T follicular helper cells that further expand the local B cell pool in an IL-21-dependent manner. We also found that commensal induced antibodies can protect the host against subsequent infection with the same microbe demonstrating the importance of this line of defense in maintaining barrier protection. Collectively, our observations highlight the autonomous potential of skin organizational flexibility and for the first time demonstrate that B cells represent an indispensable local cutaneous compartment that actively maintains skin immunity.

Immunosenescence and Skin: A State of Art of Its Etiopathogenetic Role and Crucial Watershed for Systemic Implications.

Immunosenescence is a complex multifactorial phenomenon consisting of wide-ranging remodeling of the immune system during the life span, resulting in an age-related qualitative-quantitative decline of immune cells and cytokines. A growing body of evidence in the international literature is highlighting the etiopathogenetic role of skin immunosenescence in the onset of various dermatologic conditions. Skin immunosenescence also serves as an interesting watershed for the onset of system-wide conditions in the context of allergic inflammation. Moreover, in recent years, an increasingly emerging and fascinating etiopathogenetic parallelism has been observed between some mechanisms of immunosenescence, both at cutaneous and systemic sites. This would help to explain the occurrence of apparently unconnected comorbidities. Throughout our review, we aim to shed light on emerging immunosenescent mechanisms shared between dermatologic disorders and other organ-specific diseases in the context of a more extensive discussion on the etiopathogenetic role of skin immunosenescence. A promising future perspective would be to focus on better understanding the mutual influence between skin and host immunity, as well as the influence of high inter-individual variability on immunosenescence/inflammaging. This can lead to a more comprehensive "immunobiographic" definition of each individual.

346 Leveraging skin immunity to counteract senescence

346 Leveraging skin immunity to counteract senescence

Potential effects of shift work on skin autoimmune diseases.

Shift work is associated with systemic chronic inflammation, impaired host and tumor defense and dysregulated immune responses to harmless antigens such as allergens or auto-antigens. Thus, shift workers are at higher risk to develop a systemic autoimmune disease and circadian disruption with sleep impairment seem to be the key underlying mechanisms. Presumably, disturbances of the sleep-wake cycle also drive skin-specific autoimmune diseases, but epidemiological and experimental evidence so far is scarce. This review summarizes the effects of shift work, circadian misalignment, poor sleep, and the effect of potential hormonal mediators such as stress mediators or melatonin on skin barrier functions and on innate and adaptive skin immunity. Human studies as well as animal models were considered. We will also address advantages and potential pitfalls in animal models of shift work, and possible confounders that could drive skin autoimmune diseases in shift workers such as adverse lifestyle habits and psychosocial influences. Finally, we will outline feasible countermeasures that may reduce the risk of systemic and skin autoimmunity in shift workers, as well as treatment options and highlight outstanding questions that should be addressed in future studies.

Modern research progress in external application of traditional Chinese medicine to acupoints

Traditional Chinese medicine(TCM) has a long history and abundant experience in external therapy, which marks human wisdom. In the early history of human, people found that fumigation, coating, and sticking of some tree branches and herb stems can help alleviate scabies and remove parasites in productive labor, which indicates the emergence of external therapy. Pathogen usually enters the body through the surface, so external therapy can be used to treat the disease. External therapy is among the major characteristic of surgery of TCM. As one of the external therapies in TCM, external application to acupoints smooths the zang-fu organs through meridians and collaterals, thereby harmonizing yin and yang. This therapy emerged in the early society, formed the Spring and Autumn Period and the Warring States Period, improved in the Song and Ming dynasties, and matured in the Qing dynasty. With the efforts of experts in history, it has had a mature theory. According to modern research, it can avoid the first-pass effect of liver and the gastrointestinal irritation and improve the bioavailability of Chinese medicine. Based on the effect of Chinese medicine and the theory of meridian and collateral, it can stimulate the acupoints, exert regulatory effect on acupoints, and give full play to the efficacy of TCM and the interaction of the two. Thereby, it can regulate qi and blood and balance yin and yang, thus being widely used in the treatment of diseases. In this paper, the use of external application to acupoints, the effect on skin immunity, the regulation of neuro-inflammatory mechanism, the relationship between acupoint application and human circulation network, and the development of its dosage form were summarized through literature review. On this basis, this study is expected to lay a foundation for further research.

Skin Beautification with an ImmunatuRNA® Complex: A Natural Complex Based on Yeast RNA and Marine Derivatives on the Human Skin Immunity and Microbiome Composition

The skin is the largest organ of human body implicated in vital physiological and immunological processes, including protection against injury, infections, and environmental exposures. Nevertheless, a number of negative external and internal factors, including increased pollution along with modern lifestyle can significantly influence on the skin immunity, promote aging and reduce regenerative capabilities. Cosmetic formulations based on natural ingredients, including plant and marine/algae extracts, and microbial-derived bio-actives may help to maintain healthy skin condition and protect its beautiful appearance. The ImmunatuRNA®* (*The trademark ImmunatuRNA® is a registered trademark in the European Union EUTM 018365297 and Great Britain UK00003630172. Any reference to the registration of the ImmunatuRNA® trademark applies to the designated territories), a signature complex (VRFD SA/VERDILAB Switzerland) based on the Natural RNA molecules obtained from yeasts, with added marine exopolysaccharides and natural hyaluronic acid with potential benefits for antibacterial and antiradical defense and maintaining skin detox homeostasis. Therefore, the main aim of this study is to experimentally assess the ImmunatuRNA® complex capabilities to enhance natural skin antioxidant defenses and protection against oxidative stress, by using human fibroblast cell culture. Additionally, this study will investigate the effects of the skincare products with added ImmunatuRNA® complex on the skin microbiome composition in the group of healthy adults with various skin types. The results obtained from the in vitro studies consistently demonstrated that treatment with an ImmunatuRNA® complex protects human fibroblasts against exposure to pro-oxidants, while at the same time enhances anti-oxidative defenses of these cells, demonstrated as reduced formation of free radicals and upregulation of SIRT-1 protein. Furthermore, the cosmetic intervention carried on the group of 10 healthy human volunteers with different skin types (oily, dry, combined, normal) aged between 23 and 65 years old demonstrated that using interchangeably of two cosmetic products-a Natural Moisturizer Probiotic Cream and Natural Detox Replenishing Face Mask containing the ImmunatuRNA® complex, for 4-weeks led to favorable changes in the composition of skin microbiome observed as a reduction of relative abundance of adverse microorganisms, previously linked to the skin inflammation and infections, such as Citrobacter koseri, Bacillus spp., Enterococcus spp., Alcaligenes spp., Pantoea spp. and Staphylococcus aureus. Based on following results, the use of skincare products containing the ImmunatuRNA® complex can help maintain a healthy skin microbiome while possibly preventing against infections and negative environmental exposures, in particularly against oxidative stress in healthy adults with all types of skin with age range 23-65 years old.

Poly(l-lactic acid) Scaffold Releasing an α4β1 Integrin Agonist Promotes Nonfibrotic Skin Wound Healing in Diabetic Mice.

Skin wound healing is a highly complex process that continues to represent a major medical problem, due to chronic nonhealing wounds in several classes of patients and to possible fibrotic complications, which compromise the function of the dermis. Integrins are transmembrane receptors that play key roles in this process and that offer a recognized druggable target. Our group recently synthesized GM18, a specific agonist for α4β1, an integrin that plays a role in skin immunity and in the migration of neutrophils, also regulating the differentiated state of fibroblasts. GM18 can be combined with poly(l-lactic acid) (PLLA) nanofibers to provide a controlled release of this agonist, resulting in a medication particularly suitable for skin wounds. In this study, we first optimized a GM18-PLLA nanofiber combination with a 7-day sustained release for use as skin wound medication. When tested in an experimental pressure ulcer in diabetic mice, a model for chronic nonhealing wounds, both soluble and GM18-PLLA formulations accelerated wound healing, as well as regulated extracellular matrix synthesis toward a nonfibrotic molecular signature. In vitro experiments using the adhesion test showed fibroblasts to be a principal GM18 cellular target, which we then used as an in vitro model to explore possible mechanisms of GM18 action. Our results suggest that the observed antifibrotic behavior of GM18 may exert a dual action on fibroblasts at the α4β1 binding site and that GM18 may prevent profibrotic EDA-fibronectin-α4β1 binding and activate outside-in signaling of the ERK1/2 pathways, a critical component of the wound healing process.

Alterations of the Mucosal Immune Response and Microbial Community of the Skin upon Viral Infection in Rainbow Trout (Oncorhynchus mykiss).

The skin is the largest organ on the surface of vertebrates, which not only acts as the first line of defense against pathogens but also harbors diverse symbiotic microorganisms. The complex interaction between skin immunity, pathogens, and commensal bacteria has been extensively studied in mammals. However, little is known regarding the effects of viral infection on the skin immune response and microbial composition in teleost fish. In this study, we exposed rainbow trout (Oncorhynchus mykiss) to infectious hematopoietic necrosis virus (IHNV) by immersion infection. Through pathogen load detection and pathological evaluation, we confirmed that IHNV successfully invaded the rainbow trout, causing severe damage to the epidermis of the skin. qPCR analyses revealed that IHNV invasion significantly upregulated antiviral genes and elicited strong innate immune responses. Transcriptome analyses indicated that IHNV challenge induced strong antiviral responses mediated by pattern recognition receptor (PRR) signaling pathways in the early stage of the infection (4 days post-infection (dpi)), and an extremely strong antibacterial immune response occurred at 14 dpi. Our 16S rRNA sequencing results indicated that the skin microbial community of IHNV-infected fish was significantly richer and more diverse. Particularly, the infected fish exhibited a decrease in Proteobacteria accompanied by an increase in Actinobacteria. Furthermore, IHNV invasion favored the colonization of opportunistic pathogens such as Rhodococcus and Vibrio on the skin, especially in the later stage of infection, leading to dysbiosis. Our findings suggest that IHNV invasion is associated with skin microbiota dysbiosis and could thus lead to secondary bacterial infection.

Structural design strategies of microneedle-based vaccines for transdermal immunity augmentation.

As microneedle-based vaccines possess advantages of high compliance, moderate invasiveness and convenience that are highly relevant to their unique design, they are becoming an indispensable piece of the puzzle in the field of medical applications. By selecting appropriate materials and methods convenient for precise control over the structure and morphology, MN-based vaccines with strong mechanical properties and variable forms can be fabricated, and specific biomolecules can be used for monitoring or augmenting human immunity. The structural design strategies of MN-based vaccines are highlighted in this review, following a brief discussion of the mechanism of skin immunity and the classification and fabrication approaches of MNs. The biomedical applications of MN-based vaccines, including sampling from interstitial fluid and therapy in infectious diseases and cancers, have also been demonstrated. Finally, the central challenges in this field and opportunities for future developments are also deliberated.

ODP265 Bph, Androgenic Alopecia, and Acne - Markers of Progesterone Deficiency

Abstract Materials and methods The study at this stage involves 6 male patients from 21 to 50 years with the diagnosis: BPH. Androgenic alopecia. Acne disease. All patients were examined for vitamin D in the blood by calcidiol 25(OH)D using mass spectrometry and steroid hormone levelsusing a steroid profile in saliva by mass spectrometry. Findings. Vitamin D level in three patients was below 30 ng/ml, in three patients - below 20 ng/ml. The steroid profile in the saliva of all six patients revealed progesterone deficiency, with normal testosterone levels. Patients were prescribed vitamin D in a dose of 20,000 IU daily and progesterone in a dose of 100 mg daily; patients with acne were additionally prescribed topical treatment - progesterone in gel form. As a result, after 6 months of using this therapy, patients have a cessation of hair loss, growth of downy hair and transition of downy hair to terminal hair,improvement in all patients was 80-90%. Two patients with the papulopustular form of moderate acne improved by 90%, a patient with the conglobate form improved by 50% (transition to the papulopustular form of moderate severity). Improvement of clinical picture of symptoms of BPH is also noted: decrease of IPSS questionnaire score to 7-9. Vitamin D level from 70 to 100 ng/ml. On the steroid profile of saliva, the levels of testosterone and progesterone are within normal limits. Interpretation. The main cause of androgenetic alopecia, acne, BPH is thought to be: an excess of DHT (dihydrotestosterone), increased activity of 5-α-reductase enzyme. These three diseases accompany each other. The main drug which is used 5-α-reductase blockers. The side effects of which greatly exceed the benefitsof treating. Vitamin D is involved in regulation of proliferation, differentiation and apoptosis of keratinocytes, regulation of skin immunity, regulation of pro-inflammatory cytokines, stimulation of the expression of antimicrobial peptides, regulation of the integrity and permeability of the lipid barrier, reducing the severity of systemic inflammation, regulation of cellular, humoral, congenital and acquired immunity. Also, in an in vitro study it was found that progesterone can inhibit the activity of 5-α-reductase, so in the skin the activity of this enzyme is reduced by 97±5.3%. And the positive effect was also established in the treatment of prostate diseases, inhibiting 5-α-reductase, progesterone reduces the growth of the prostate gland and the growth of prostate cancer cells. Conclusion Laboratory studies have shown vitamin D and progesterone deficiencies in patients with these diseases. Correction of these deficiencies resulted in improvement both in BPH (reduction of clinical manifestations) and in androgenic alopecia (cessation of hair loss and restoration of terminal hair growth) and acne (significant reduction of inflammation). Presentation: No date and time listed

Genetic/Environmental Contributions and Immune Dysregulation in Children with Atopic Dermatitis.

Atopic dermatitis (AD) is one of the most common skin conditions in humans. AD affects up to 20% of children worldwide and results in morbidity for both patients and their caregivers. The basis of AD is an interplay between genetics and the environment characterized by immune dysregulation. A myriad of mutations that compromise the skin barrier and/or immune function have been linked to AD. Of these, filaggrin gene (FLG) mutations are the most evidenced. Many other mutations have been implicated in isolated studies that are often unreplicated, creating an archive of genes with potential but unconfirmed relevance to AD. Harnessing big data, polygenic risk scores (PRSs) and genome-wide association studies (GWAS) may provide a more practical strategy for identifying the genetic signatures of AD. Epigenetics may also play a role. Staphylococcus aureus is the most evidenced microbial contributor to AD. Cutaneous dysbiosis may result in over-colonization by pathogenic strains and aberrant skin immunity and inflammation. Aeroallergens, air pollution, and climate are other key environmental contributors to AD. The right climate and/or commensals may improve AD for some patients.

Pellino1 Restricts Herpes Simplex Virus Infections in the Epidermis and Dissemination to Sebaceous Glands

Nearly all adults are infected with one or more herpes viruses. The most common are herpes simplex virus (HSV)-1 and HSV-2, which upon reactivation can cause painful skin and mucosal erosions. Patients who are immune compromised often experience frequent, atypical, or chronic lesions and thus a greatly diminished QOL. Pellino1 is a ubiquitin ligase involved in IL-1 and toll-like receptor signaling; however, the role of Pellino1 in skin immunity against HSV is unknown. In this study, using the mouse-flank HSV-1 skin infection model, we show that Pellino1 has several critical functions during active viral replication. Peli1‒/‒ mice succumb more than wild-type mice to systemic disease and develop larger zosteriform skin lesions along affected dermatomes. In Pellino1-deficient mice, the virus spread extensively through the epidermis and follicular infundibulum into sebaceous glands where sebocytes were found positive for the virus. The latter did not appear to involve a shift in how the virus migrated through the nervous system. Immunohistochemistry revealed delayed recruitment of myeloid and T cells to the infected epidermis in Peli1‒/‒ mice. This was associated with decreased expression of the cytokine mRNAs Il1a, Il36b and 2610528A11Rik; the latter also known as Gpr15l. In conclusion, Pellino1 plays important roles in restricting viral dissemination, and the involved pathways may represent novel therapeutic targets in patients with frequent or chronic HSV infections.

Down-regulation of MCH II molecules by ubiquitination is required for the accumulation of CD206+ monocyte-derived DCs in lymph nodes

Migratory DCs play a critical role in skin immunity. A subset of these cells infiltrate skin come from the extravasation of blood monocytes (P1) that continuously differentiate into an intermediate stage (P2) before becoming fully functional DCs (P3), which can migrate to skin draining lymph nodes (sdLNs). During their development into monocyte-derived DCs (moDCs), in parallel with the downregulation of Ly-6C, P1-P2-P3 progressively upregulate MHC class II molecules (MHCII) and the mannose receptor (CD206). To study the role of MHCII expression in the biology of migratory DCs. We studied by flow cytometry the development and migration of skin moDCs using four transgenic mouse models expressing different MHCII levels. Using CD206 as a surrogate marker for MHCII to identify P1, P2 and P3, we found that variations in the levels of MHCII did not affect the development of skin moDCs. However, tempering with ubiquitination of I-A resulted in the over-expression of MHCII, a decrease in the expression of IRF4 and CCR7, and prevented migration of skin moDCs to sdLNs. Interestingly, mice overexpressing MHCII developed larger tumors in B16-mel-anoma model. However, a GM-CSF-producing B16 variant increased the expression of IRF4 in tumor moDCs and restored their migration to sdLNs. The data show that although not required for their development in the skin, the down-regulation of MHCII by ubiquitination is crucial for IRF4\CCR7 dependent migration of CD206+DCs to the sdLN in homeostasis and during inflammation.

34783 Metagenomic microbial profiling of keratinocyte carcinomas in solid organ transplant recipients

In healthy individuals, a symbiotic relationship exists between the host and its microbiota; however, disruption of this ecosystem may lead to chronic inflammation and skin diseases such as atopic dermatitis, psoriasis, rosacea, and acne. Altered microbiota has also been linked to malignancies such as breast, colorectal, and gastric cancers. Solid organ transplant recipients are at increased risk of malignancy, especially at microbiota-rich sites such as the skin. In contrast, the incidence of common malignancies in more sterile areas (i.e., breast and prostate) are reduced post-transplantation. Medication-induced immunosuppression may play a role in carcinogenesis, in part by decreasing immune-mediated tumor surveillance. However, it does not account for the striking increase in cancer at high microbial density sites. Therefore, it is essential to understand the complex interplay between the skin microbiota, inflammation, and immunity in health and disease. To date, there are no studies that have investigated the cutaneous microbiota in transplant recipients. We hypothesize that metagenomic sequencing will reveal microbial dysbiosis in patients post-transplant, thereby identifying tumour-specific species/strains of bacteria. By understanding the microbiota-host interactions of keratinocyte carcinomas in transplant recipients, we further the development of diagnostic and prognostic tools essential for the management of skin cancer. Identifying specific tumour-associated microbes holds great therapeutic potential, with treatment options including prebiotics, probiotics, antibiotics, and microbial transplants.

33260 Dermal delivery of 12-hydroxystearic acid for barrier benefits from skin cleansers – An ex vivo and in silico study

12-hydroxystearic acid (12-HSA) is known to benefit skin barrier function and immunity as demonstrated from cell culture and reconstructed tissue experiments However, dermal penetration of 12HSA has not been well studied, particularly when deposited from cleansers. To assess the effectiveness of delivering 12-HSA to the viable epidermis (VE) from cleansers via ex-vivo measurements and validation of established in silico simulation methods for this active. 12-HSA delivery was quantified using ex vivo dermal delivery measurements. The transdermal delivery data was used to validate results obtained from in silico simulation and further insights on 12HSA delivery were then obtained from the simulations. Both ex vivo and in silico results showed 12-HSA can be successfully delivered to the VE in a dose-dependent manner. We show that we can attain ∼10uM or higher concentrations of 12-HSA in the VE within 24 hours from a single use of cleanser. At such levels 12-HSA has been demonstrated to enhance skin biological processes. Further, simulations predicted that a higher level of 12-HSA can be achieved and maintained at a stable level in the VE after three daily cleanser applications. These results suggested that it is feasible to deliver 12-HSA from cleansers at a level which can provide a functional benefit for skin health.