A microRNA focus on acne.

Acne (syn. acne vulgaris) is a common inflammatory skin disorder associated with puberty and adolescence. The disease is characterized by comedoneous lesions, papules, pustules, and nodules that are mostly found on the face. These lesions are caused by intricate interactions between the pilosebaceous unit and the Cutibacterium acnes (C. acnes) bacteria. Unhealthy acne and its aftereffects, like pigment changes and scarring, have a detrimental impact on one's quality of life. Recent years have seen a sharp increase in the approval of nucleic acid therapies (NATs), such as antisense oligonucleotides and short-interfering RNA medications, for rare diseases for which there are few or no effective treatments. These developments suggest that NATs may be useful in acne treatment plans down the road, as do clinical trials for microRNA (miRNA) modulation in skin contexts. We highlight promising miRNA targets for anti-acne therapy in this review. We outline the pathophysiology of acne in brief and emphasize the functions of C. acnes. Next, we concentrate on the distinct impacts of biofilm and planktonic C. acnes on a Toll-like receptor 2 axis that spans miR-146a-5p, which was recently discovered. Before discussing the potential contributions of miR-21-5p, miR-233-3p, and miR-150-5p to inflammatory axes in acne, we evaluate miR-146a-5p in sebocytes. Finally, we address patient involvement in miRNA-related acne research and translational perspectives.

Activity of apremilast in a patient with severe pemphigus vulgaris: case report.

Introduction: Although the treatment for pemphigus vulgaris (PV) has been revolutionized by the use of rituximab combined with corticosteroids, new effective therapies with a better safety profile are needed. Observation: A 67-year-old woman was diagnosed with severe mucosal PV, which was initially misdiagnosed as atypical Behçet's disease. Following an unsuccessful colchicine treatment, significant improvement was observed upon the introduction of apremilast: reduced pain, fewer lesions, and a stabilized weight. The discontinuation of apremilast led to a rapid relapse. Retrospective analysis through anti-Dsg3 ELISA indicated a gradual decrease in antibody levels during the apremilast treatment. Discussion: Apremilast, a phosphodiesterase 4 inhibitor approved for psoriasis and Behçet's disease's related oral ulcers treatment, demonstrated its efficacy in this PV case. This is the second case report highlighting the effectiveness of apremilast for PV treatment. Apremilast's ability to upregulate cyclic adenosine monophosphate (cAMP) levels appears to contribute to the stabilization of keratinocyte adhesion. Conclusion: Apremilast may be a promising therapeutic option for the treatment of pemphigus, with an innovative mechanism of action, no induced immunosuppression, and good tolerance. It could be a good alternative to steroids, in the treatment regimen of steroids combined with rituximab.

Effect of Isoscopoletin on Cytokine Expression in HaCaT Keratinocytes and RBL-2H3 Basophils: Preliminary Study.

Isoscopoletin is a compound derived from various plants traditionally used for the treatment of skin diseases. However, there have been no reported therapeutic effects of isoscopoletin on atopic dermatitis (AD). AD is a chronic inflammatory skin disease, and commonly used treatments have side effects; thus, there is a need to identify potential natural candidate substances. In this study, we aimed to investigate whether isoscopoletin regulates the inflammatory mediators associated with AD in TNF-α/IFN-γ-treated HaCaT cells and PMA/ionomycin treated RBL-2H3 cells. We determined the influence of isoscopoletin on cell viability through an MTT assay and investigated the production of inflammatory mediators using ELISA and RT-qPCR. Moreover, we analyzed the transcription factors that regulate inflammatory mediators using Western blots and ICC. The results showed that isoscopoletin did not affect cell viability below 40 µM in either HaCaT or RBL-2H3 cells. Isoscopoletin suppressed the production of TARC/CCL17, MDC/CCL22, MCP-1/CCL2, IL-8/CXCL8, and IL-1ß in TNF-α/IFN-γ-treated HaCaT cells and IL-4 in PMA/ionomycin-treated RBL-2H3 cells. Furthermore, in TNF-α/IFN-γ-treated HaCaT cells, the phosphorylation of signaling pathways, including MAPK, NF-κB, STAT, and AKT/PKB, increased but was decreased by isoscopoletin. In PMA/ionomycin-treated RBL-2H3 cells, the activation of signaling pathways including PKC, MAPK, and AP-1 increased but was decreased by isoscopoletin. In summary, isoscopoletin reduced the production of inflammatory mediators by regulating upstream transcription factors in TNF-α/IFN-γ-treated HaCaT cells and PMA/ionomycin-treated RBL-2H3 cells. Therefore, we suggest that isoscopoletin has the potential for a therapeutic effect, particularly in skin inflammatory diseases such as AD, by targeting keratinocytes and basophils.

Dermatomyositis-like skin eruptions under hydroxyurea therapy conceal TP53-mutated atypical keratinocytes: A histopathologic and molecular pathologic case series.

Hydroxyurea is an antimetabolite that inhibits DNA synthesis and is used as a treatment option in chronic myeloproliferative disorders. Rarely, "dermatomyositis (DM)-like" skin lesions are observed after long-term therapy. In this case series, five skin biopsies of four patients were evaluated by histology, immunohistochemistry, and next-generation sequencing of the TP53 gene locus. All biopsies showed focal basal pleomorphic keratinocytes and suprabasal aberrant p53 expression as well as sparse to severe vacuolar interface dermatitis. Histopathologically, "DM-like" skin lesions can be clearly distinguished from DM by marked subepidermal fibrosis, vascular proliferation, and the absence of dermal mucin deposits. In 75% of the specimens multiple, partly inactivating and/or pathogenic point mutations of TP53 were found in low frequencies. "DM-like" skin eruptions as a long-term consequence of hydroxyurea therapy are possibly not chemotherapy-associated benign toxic changes, but rather inflammatory reactions to complex keratinocyte alterations that clinically mimic the picture of DM. Synergistic mutagenic effects of hydroxyurea and sunlight might be responsible for this unique drug side effect and could provide a pathogenic link to the known increased risk of skin cancer in these patients.

Melanin accumulation in acanthotic seborrheic keratosis: Reduced proliferation and early differentiation of keratinocytes and increased number of melanocytes.

Seborrheic keratosis (SK) is a common benign tumour, often associated with hyperpigmentation. To investigate the mechanism of melanin accumulation in SK, we have conducted comprehensive gene expression and histological analyses. We obtained five pairs of skin samples, including non-lesional and SK samples, from the backs of three male Japanese participants aged 40-59 years. To examine melanocytes and keratinocytes in SK, three pairs of skin samples were separated by laser capture microdissection into the basal layer and the other layer in the epidermis. We performed a comprehensive gene expression analysis to identify differentially expressed genes between non-lesional and SK skin, followed by gene ontology and pathway analysis. We found abnormal morphogenesis and cell proliferation in the basal layer, along with increased immune response and impaired cell differentiation and metabolism in the other layer of SK. We focused on cell proliferation and differentiation, as these are directly associated with melanin accumulation. Immunohistochemical analyses of Ki67, keratin 10, and keratin 14 demonstrated the decreases in the proliferation and early differentiation of the epidermis. Contrarily, no significant changes were observed in terminal differentiation markers, filaggrin and loricrin. Although the number of melanocytes was higher in SK than in non-lesional skin, melanogenic activity showed no difference. These results indicated that melanin accumulation in SK is caused by delayed melanin excretion due to reduced turnover around the basal and spinous layers of the epidermis and melanin production due to an increased number of melanocytes. Our findings provide new insights for therapeutic approaches in SK.

The Role of PGC-1α in Aging Skin Barrier Function.

Skin provides a physical and immune barrier to protect the body from foreign substances, microbial invasion, and desiccation. Aging reduces the barrier function of skin and its rate of repair. Aged skin exhibits decreased mitochondrial function and prolonged low-level inflammation that can be seen in other organs with aging. Peroxisome proliferator-activated receptor (PPAR)-γ coactivator-1α (PGC-1α), an important transcriptional coactivator, plays a central role in modulating mitochondrial function and antioxidant production. Mitochondrial function and inflammation have been linked to epidermal function, but the mechanisms are unclear. The aim of this review is to discuss the mechanisms by which PGC-1α might exert a positive effect on aged skin barrier function. Initially, we provide an overview of the function of skin under physiological and aging conditions, focusing on the epidermis. We then discuss mitochondrial function, oxidative stress, cellular senescence, and inflamm-aging, the chronic low-level inflammation observed in aging individuals. Finally, we discuss the effects of PGC-1α on mitochondrial function, as well as the regulation and role of PGC-1α in the aging epidermis.

Dysregulated tryptophan metabolism and AhR pathway contributed to CXCL10 upregulation in stable non-segmental vitiligo.

BACKGROUND: Tryptophan metabolism dysregulation has been observed in vitiligo. However, drawing a mechanistic linkage between this metabolic disturbance and vitiligo pathogenesis remains challenging. OBJECTIVE: Aim to reveal the characterization of tryptophan metabolism in vitiligo and investigate the role of tryptophan metabolites in vitiligo pathophysiology. METHODS: LC-MS/MS, dual-luciferase reporter assay, ELISA, qRT-PCR, small interfering RNA, western blotting, and immunohistochemistry were employed. RESULTS: Kynurenine pathway activation and KYAT enzyme-associated deviation to kynurenic acid (KYNA) in the plasma of stable non-segmental vitiligo were determined. Using a public microarray dataset, we next validated the activation of kynurenine pathway was related with inflammatory-related genes expression in skin of vitiligo patients. Furthermore, we found that KYNA induced CXCL10 upregulation in keratinocytes via AhR activation. Moreover, the total activity of AhR agonist was increased while the AhR concentration per se was decreased in the plasma of vitiligo patients. Finally, higher KYAT, CXCL10, CYP1A1 and lower AhR expression in vitiligo lesional skin were observed by immunohistochemistry staining. CONCLUSION: This study depicts the metabolic and genetic characterizations of tryptophan metabolism in vitiligo and proposes that KYNA, a tryptophan-derived AhR ligand, can enhance CXCL10 expression in keratinocytes.

Full-spectrum cannabidiol reduces UVB damage through the inhibition of TGF-ß1 and the NLRP3 inflammasome.

The thermodynamic characteristics, antioxidant potential, and photoprotective benefits of full-spectrum cannabidiol (FS-CBD) against UVB-induced cellular death were examined in this study. In silico analysis of CBD showed antioxidant capacity via proton donation and UV absorption at 209.09, 254.73, and 276.95 nm, according to the HAT and SPLET methodologies. FS-CBD protected against UVB-induced bacterial death for 30 min. FS-CBD protected against UVB-induced cell death by 42% (1.5 µg/mL) and 35% (3.5 µg/mL) in an in vitro keratinocyte cell model. An in vivo acute irradiated CD-1et/et mouse model (UVB-irradiated for 5 min) presented very low photoprotection when FS-CBD was applied cutaneously, as determined by histological analyses. In vivo skin samples showed that FS-CBD regulated inflammatory responses by inhibiting the inflammatory markers TGF-ß1 and NLRP3. The docking analysis showed that the CBD molecule had a high affinity for TGF-ß1 and NLRP3, indicating that protection against inflammation might be mediated by blocking these proinflammatory molecules. This result was corroborated by the docking interactions between CBD and TGF-ß1 and NLRP3, which resulted in a high affinity and inhibition of both proteins The present work suggested a FS-CBD moderate photoprotective agent against UVB light-induced skin damage and that this effect is partially mediated by its anti-inflammatory activity.

Characteristics and Clinical Implications of Immunoglobulins Derived from Non B Cells in the Skin.

Skin is the most prominent tissue and organ, as well as the first line of defence, of the body. Because it is situated on the body's surface, it is constantly exposed to microbial, chemical, and physical factors such as mechanical stimulation. Therefore, skin has evolved substantial immune defences, regenerative ability, and anti-injury capacity. Epidermal cells produce antibacterial peptides that play a role in immune defence under physiological conditions. Additionally, IgG or IgA in the skin also participates in local anti-infective immunity. However, based on the classical theory of immunology, Ig can only be produced by B cells which should be derived from local B cells. This year, thanks to the discovery of Ig derived from non B cells (non B-Ig), Ig has also been found to be expressed in epidermal cells and contributes to immune defence. Epidermal cell-derived IgG and IgA have been demonstrated to have potential antibody activity by binding to pathogens. However, these epidermal cell-derived Igs show different microbial binding characteristics. For instance, IgG binds to Staphylococcus aureus and IgA binds to Staphylococcus epidermidis. Epidermal cells producing IgG and IgA may serve as an effective defense mechanism alongside B cells, providing a novel insight into skin immunity.

In Silico and In Vitro Studies on an Asymmetrical Porphyrin Derivative with Therapeutic Potential in Skin Disorders.

For developing novel photosensitizers with therapeutic potential in non-malignant and malignant cutaneous disorders, the unsymmetrical porphyrin, 5-(2-hydroxy-3-methoxyphenyl)-10, 15, 20-tris-(4-carboxymethylphenyl) porphyrin, was evaluated in silico and in vitro. The cellular uptake of the investigated porphyrin and its ability to perform photodynamic therapy were investigated in terms of the viability, proliferation, and necrosis of human HaCaT keratinocytes and human Hs27 skin fibroblasts, in correlation with the predictions regarding diffusion through cell membranes, ADMET profile (absorption, distribution, metabolism, elimination, toxicity), and potential pharmacological mechanism. Molecular docking and 250 ns molecular dynamics simulations revealed that P5.2 has the potential to form a relatively stable complex with the carbonic anhydrase IX catalytic site, the lowest predicted free energy of binding (MM/PBSA) being -39.097 kcal/mol. The results of the in vitro study showed that P5.2 is incorporated within 24 h in the investigated cells, especially in HaCaT keratinocytes, indicating its photosensitizing ability. Nevertheless, P5.2 does not exert significant cytotoxicity in "dark" conditions. In turn, PDT induced a decrease in the number of metabolically active HaCaT keratinocytes within 24 h, accompanied by a 4-fold increase in lactate dehydrogenase release, indicating its ability to perform PDT in human skin cells. The experimental results suggest that the asymmetrical porphyrin is a promising candidate theranostics agent for skin disorders.

Antimicrobial Peptide Reduces Cytotoxicity and Inflammation in Canine Epidermal Keratinocyte Progenitor Cells Induced by Pseudomonas aeruginosa Infection.

The direct effects and antimicrobial activity of synthetic antimicrobial peptides (AMPs) obtained from dogs, including cBD, cBD103, and cCath, against P. aeruginosa wild-type strain PAO1 and canine keratinocytes were analyzed. Antibacterial effects on planktonic bacteria were assessed by determining the minimum bactericidal concentrations (MBCs) of AMPs and by a time-kill assay. Antibiofilm effects were assessed using the microtiter plate assay. We also evaluated the effects of AMPs on cell cytotoxicity and host immune response induced by stimulating canine epidermal keratinocyte progenitor (CPEK) cells with PAO1 and its LPS. cBD, cBD103, and cCath all exhibited dose-dependent antimicrobial and antibiofilm effects. In particular, 25 µg/mL cBD103 showed rapid bactericidal activity within 60 min and inhibited biofilm formation. In addition, pretreatment with cBD103 (25 µg/mL) and cCath (50 µg/mL) 1 h before stimulation significantly reduced the cytotoxicity of the CPEK cells by PAO1 and LPS-induced IL-6 and TNF-a expressions. cBD had little effect on the response to PAO1 and LPS in the cells. These results indicate the therapeutic potential of AMPs in P. aeruginosa skin infections. However, further studies on the mechanism of action of AMPs in keratinocytes and clinical trials are needed.

Efficient Generation of Pancreatic Progenitor Cells from Induced Pluripotent Stem Cells Derived from a Non-Invasive and Accessible Tissue Source-The Plucked Hair Follicle.

The advent of induced pluripotent stem cell (iPSC) technology has brought about transformative advancements in regenerative medicine, offering novel avenues for disease modeling, drug testing, and cell-based therapies. Patient-specific iPSC-based treatments hold the promise of mitigating immune rejection risks. However, the intricacies and costs of producing autologous therapies present commercial challenges. The hair follicle is a multi-germ layered versatile cell source that can be harvested at any age. It is a rich source of keratinocytes, fibroblasts, multipotent stromal cells, and the newly defined Hair Follicle-Associated Pluripotent Stem Cells (HAP). It can also be obtained non-invasively and transported via regular mail channels, making it the ideal starting material for an autologous biobank. In this study, cryopreserved hair follicle-derived iPSC lines (HF-iPS) were established through integration-free vectors, encompassing a diverse cohort. These genetically stable lines exhibited robust expression of pluripotency markers, and showcased tri-lineage differentiation potential. The HF-iPSCs effectively differentiated into double-positive cKIT+/CXCR4+ definitive endoderm cells and NKX6.1+/PDX1+ pancreatic progenitor cells, affirming their pluripotent attributes. We anticipate that the use of plucked hair follicles as an accessible, non-invasive cell source to obtain patient cells, in conjunction with the use of episomal vectors for reprogramming, will improve the future generation of clinically applicable pancreatic progenitor cells for the treatment of Type I Diabetes.

LncRNA MIR181A2HG inhibits keratinocytes proliferation through miR-223-3p/SOX6 axis.

BACKGROUND: Psoriasis is a complex and recurrent chronic inflammatory skin disease, and the abnormal proliferation of keratinocytes plays a crucial role in the pathogenesis of psoriasis. Long non-coding RNAs (lncRNAs) play an indispensable role in regulating cellular functions. This research aims to explore the potential impact of lncRNA MIR181A2HG on the regulation of keratinocyte proliferation. METHODS: The expression level of MIR181A2HG and the mRNA level of KRT6, KRT16, and SOX6 were assessed using qRT-PCR. The viability and proliferation of keratinocytes were evaluated using CCK-8 and EdU assays. Cell cycle analysis was performed using flow cytometry. Dual-luciferase reporter assays were applied to test the interaction among MIR181A2HG/miR-223-3p/SOX6. Protein level was detected by Western blotting analysis. RESULTS: The findings indicated that psoriasis lesions tissue exhibited lower levels of MIR181A2HG expression compared to normal tissue. The overexpression of MIR181A2HG resulted in the inhibition of HaCaT keratinocytes proliferation. The knockdown of MIR181A2HG promoted cell proliferation. The dual-luciferase reporter assay and rescue experiments provided evidence of the interaction among MIR181A2HG, SOX6, and miR-223-3p. CONCLUSIONS: The lncRNA MIR181A2HG functions as a miR-223-3p sponge targeting SOX6 to regulate the proliferation of keratinocytes, which suggested that MIR181A2HG/miR-223-3p/SOX6 might be potential diagnostic and therapeutic targets for psoriasis.

ATG5-mediated keratinocyte ferroptosis promotes M1 polarization of macrophages to aggravate UVB-induced skin inflammation.

Autophagy participates in the regulation of ferroptosis. Among numerous autophagy-related genes (ATGs), ATG5 plays a pivotal role in ferroptosis. However, how ATG5-mediated ferroptosis functions in UVB-induced skin inflammation is still unclear. In this study, we unveil that the core ferroptosis inhibitor GPX4 is significantly decreased in human skin tissue exposed to sunlight. We report that ATG5 deletion in mouse keratinocytes strongly protects against UVB-induced keratinocyte ferroptosis and skin inflammation. Mechanistically, ATG5 promotes the autophagy-dependent degradation of GPX4 in UVB-exposed keratinocytes, which leads to UVB-induced keratinocyte ferroptosis. Furthermore, we find that IFN-γ secreted by ferroptotic keratinocytes facilitates the M1 polarization of macrophages, which results in the exacerbation of UVB-induced skin inflammation. Together, our data indicate that ATG5 exacerbates UVB-induced keratinocyte ferroptosis in the epidermis, which subsequently gives rise to the secretion of IFN-γ and M1 polarization. Our study provides novel evidence that targeting ATG5 may serve as a potential therapeutic strategy for the amelioration of UVB-caused skin damage.

Gallic Acid Alleviates Psoriasis Keratinization and Inflammation by Regulating BRD4 Expression.

Psoriasis is a chronic non-contagious autoimmune disease. Gallic acid is a natural compound with potential health benefits, including antioxidant, anticancer, antiviral and antibacterial properties. Nevertheless, the influence of gallic acid on psoriasis has not been fully determined. This investigation aimed to discover the effect of gallic acid on psoriasis. Thirty-one pairs of psoriatic skin tissues and healthy adult human skin tissues were collected. Human keratinocytes (HaCaT cells) were transfected with interleukin 17A (IL-17A) to create the psoriatic keratinocyte model. The content of bromodomain-containing protein 4 (BRD4) microRNA was assessed using qRT-PCR testing. The content of BRD4 was detected by Western blotting. Cell migration was evaluated by conducting a wound healing assay. Cell proliferation was determined using an EdU assay. Apoptosis was detected by the TUNEL assay. The contents of interferon gamma (IFN-γ), IL-6, IL-8 and IL-17 were detected by ELISA. BRD4 was up-regulated in psoriatic skin tissues and in the IL-17A group compared to the healthy adult human skin tissues and the control group. Silencing BRD4 inhibited cell migration, proliferation and inflammatory response but induced apoptosis in IL-17A-treated HaCaT cells. Conversely, BRD4 over-expression promoted cell migration, proliferation and inflammatory response but suppressed apoptosis in IL-17A-treated HaCaT cells. Gallic acid repressed cell migration, proliferation and inflammatory response but indu-ced apoptosis in HaCaT cells transfected with IL-17A by down-regulating BRD4. Gallic acid represses cell migration, proliferation and inflammatory response but induces apoptosis in IL-17A-transfected HaCaT cells by down-regulating BRD4.

ZNT1 Regulates the Proliferation, Migration and Invasion of HaCaT Cells Infected with HPV Through the PI3K/Akt Pathway.

Background: Condyloma acuminatum (CA), which is a highly contagious sexually transmitted illness generated by human papillomavirus (HPV) infection, is characterized by abnormal proliferation of keratinocytes resulting in verrucous lesions. Although solute carrier family 30 member 1 (ZNT1) is highly expressed in CA tissues, the function of ZNT1 in CA remains unclear. Methods: HPV transfection was performed in HaCaT to simulate the CA pathological environment. The mRNA and protein levels were monitored using RT-qPCR and immunoblotting. Cell viability was found using the MTT test. Cell invasion and migration were probed using the transwell and wound healing. Results: ZNT1 expression was up-regulated in CA tissues, and HPV transfection increased the expression of ZNT1. Overexpression of ZNT1 promoted the proliferation, migration and invasion of Human immortalized keratinocyte (HaCaT) transfected with HPV. Meanwhile, ZNT1 knockdown repressed the proliferation, migration and invasion of HaCaT that HPV transfected. Further research displayed that ZNT1 promoted the proliferation, migration and invasion of HaCaT transfected with HPV through the PI3K/Akt pathway. Conclusion: Our research confirmed that ZNT1 regulated the proliferation, migration and invasion of HaCaT transfected with HPV through the PI3K/Akt pathway, providing a new target for the effective remedy of CA.

Integration of transcriptomics and spatial biology analyses reveals Galactomyces ferment filtrate promotes epidermal interconnectivity via induction of keratinocyte differentiation, proliferation and cellular bioenergetics.

OBJECTIVE: Human skin is the first line of defence from environmental factors such as solar radiation and is susceptible to premature ageing, including a disruption in epidermal differentiation and homeostasis. We evaluated the impact of a Galactomyces Ferment Filtrate (GFF) on epidermal differentiation and response to oxidative stress. METHODS: We used transcriptomics, both spatial and traditional, to assess the impact of GFF on epidermal biology and homeostasis in keratinocytes (primary or immortalized) and in ex vivo skin explant tissue. The effect of GFF on cell adhesion rates, cellular ATP levels and proliferation rates were quantitated. Oxidative phosphorylation and glycolytic rates were measured under normal and stress-induced conditions. RESULTS: Transcriptomics from keratinocytes and ex vivo skin explants from multiple donors show GFF induces keratinocyte differentiation, skin barrier development and cell adhesion while simultaneously repressing cellular stress and inflammatory related processes. Spatial transcriptomics profiling of ex vivo skin indicated basal keratinocytes at the epidermal-dermal junction and cornifying keratinocytes in the top layer of the epidermis as the primary cell types influenced by GFF treatment. Additionally, GFF significantly increases crosstalk between suprabasal and basal keratinocytes. To support these findings, we show that GFF can significantly increase cell adhesion and proliferation in keratinocytes. GFF also protected overall cellular bioenergetics under metabolic or oxidative stress conditions. CONCLUSION: Our findings provide novel insights into cellular differences and epidermal spatial localization in response to GFF, supporting previous findings that this filtrate has a significant impact on epidermal biology and homeostasis, particularly on spatially defined crosstalk. We propose that GFF can help maintain epidermal health by enhancing keratinocyte crosstalk and differentiation/proliferation balance as well as promoting an enhanced response to stress.

Skin colonization by Staphylococcus aureus in hemodialysis patients with pruritus and the effect of Staphylococcus aureus-secreted α-toxin on filaggrin expression.

Staphylococcus aureus (S. aureus) commonly reside on human skin in residents in long-term care facilities, yet its colonization and impact on the skin of hemodialysis (HD) patients have yet to be studied. The aim of the present study was to investigate the colonization of S. aureus on the skin of pruritic and non-pruritic HD patients, and the influence of S. aureus and S. aureus-secreted α-toxin on skin barrier function-related protein expression. In this study, a higher relative S. aureus count in pruritic HD patients compared to non-pruritic HD patients and healthy subjects were revealed by real-time polymerase chain reaction. S. aureus and α-toxin decreased mRNA and protein expression levels of aryl hydrocarbon receptor (AHR), ovo-like transcriptional repressor 1 (OVOL1), and filaggrin (FLG) in keratinocytes. In addition, anti-alpha-hemolysin (anti-hla) was used as an α-toxin neutralizer, and it successfully abrogated S. aureus-induced AHR, OVOL1, and FLG mRNA and protein expression downregulation. Mechanistically, α-toxin could decrease FLG activity by preventing the recruitment of AHR to the FLG promoter region. In conclusion, pruritic HD patients had higher S. aureus colonization, with S. aureus-secreted α-toxin suppressing FLG expression through the AHR-FLG axis.

Dynamics of a network mediated by IL-36 and involved in the pathogenesis of psoriasis.

The pathogenesis of the inflammatory, chronic, and common skin disease psoriasis involves immune cells, skin cells (keratinocytes), and the cytokines they secrete. Hyperproliferation and abnormal differentiation of keratinocytes are hallmarks of the disease. The roles of cytokines such as TNFα, IL-15, IL-17, and IL-23 in psoriasis have been studied through mathematical/computational models as well as experiments. However, the role of proinflammatory cytokine IL-36 in the onset and progression of psoriasis is still elusive. To explore the role of IL-36, we construct a network embodying indirect cell-cell interactions of a few immune and skin cells mediated by IL-36 based on existing knowledge. We also develop a mathematical model for the network and perform a global sensitivity analysis. Our results suggest that the model is most sensitive to a parameter that represents the level of cytokine IL-36. In addition, a steady-state analysis of the model suggests that an increase in the level of IL-36 could lead to the hyperproliferation of keratinocytes and, thus, psoriasis. Our analysis also highlights that the plaque formation and progression of psoriasis could occur through either a gradual or a switch-like increase in the keratinocyte population. We propose that the switch-like increase would be due to a bistable behavior of the network toward either a psoriatic or healthy state and could be used as a novel treatment strategy.