Bioengineered skin constructs based on mesenchymal stromal cells and acellular dermal matrix exposed to inflammatory microenvironment releasing growth factors involved in skin repair

BACKGROUND

Skin tissue engineering is a rapidly evolving field of research that effectively combines stem cells and biological scaffolds to replace damaged tissues. Human Wharton's jelly mesenchymal stromal cells (hWJ-MSCs) are essential to generate tissue constructs, due to their potent immunomodulatory effects and release of paracrine factors for tissue repair. Here, we investigated whether hWJ-MSC grown on human acellular dermal matrix (hADM) scaffolds and exposed to a proinflammatory environment maintain their ability to produce in vitro growth factors involved in skin injury repair and promote in vivo wound healing.

METHODS

We developed a novel method involving physicochemical and enzymatic treatment of cadaveric human skin to obtain hADM scaffold. Subsequently, skin bioengineered constructs were generated by seeding hWJ-MSCs on the hADM scaffold (construct 1) and coating it with human platelet lysate clot (hPL) (construct 2). Either construct 1 or 2 were then incubated with proinflammatory cytokines (IL-1α, IL-1β, IL-6, TNF-α) for 12, 24, 48, 72 and 96 h. Supernatants from treated and untreated constructs and hWJ-MSCs on tissue culture plate (TCP) were collected, and concentration of the following growth factors, bFGF, EGF, HGF, PDGF, VEGF and Angiopoietin-I, was determined by immunoassay. We also asked whether hWJ-MSCs in the construct 1 have potential toward epithelial differentiation after being cultured in an epithelial induction stimulus using an air-liquid system. Immunostaining was used to analyze the synthesis of epithelial markers such as filaggrin, involucrin, plakoglobin and the mesenchymal marker vimentin. Finally, we evaluated the in vivo potential of hADM and construct 1 in a porcine full-thickness excisional wound model.

RESULTS

We obtained and characterized the hADM and confirmed the viability of hWJ-MSCs on the scaffold. In both constructs without proinflammatory treatment, we reported high bFGF production. In contrast, the levels of other growth factors were similar to the control (hWJ-MSC/TCP) with or without proinflammatory treatment. Except for PDGF in the stimulated group. These results indicated that the hADM scaffold maintained or enhanced the production of these bioactive molecules by hWJ-MSCs. On the other hand, increased expression of filaggrin, involucrin, and plakoglobin and decreased expression of vimentin were observed in constructs cultured in an air-liquid system. In vivo experiments demonstrated the potential of both hADM and hADM/hWJ-MSCs constructs to repair skin wounds with the formation of stratified epithelium, basement membrane and dermal papillae, improving the appearance of the repaired tissue.

CONCLUSIONS

hADM is viable to fabricate a tissue construct with hWJ-MSCs able to promote the in vitro synthesis of growth factors and differentiation of these cells toward epithelial lineage, as well as, promote in a full-thickness skin injury the new tissue formation. These results indicate that hADM 3D architecture and its natural composition improved or maintained the cell function supporting the potential therapeutic use of this matrix or the construct for wound repair and providing an effective tissue engineering strategy for skin repair.

Filaggrin gene variants among Saudi patients with ichthyosis vulgaris

Ichthyoses are a heterogeneous group of cornification disorders. The most common form of ichthyoses is ichthyosis vulgaris (IV) ([OMIM] #146,700), which can be inherited as autosomal semi-dominant mutation in the filaggrin gene (FLG). We present the findings of a study involving 35 Saudi patients with a clinical diagnosis of ichthyosis vulgaris. For identifying the pathogenic mutation of their disease, we used Sanger sequencing analysis of the extracted DNA samples. We also identified the underlying 22 FLG variants, which have been seen before. However, the detected mutations do not involve the common p.R501* c. 2282del4 mutations reported in European populations. Indeed, we did not identify any statistical influence of the homozygous or heterozygous genotypes on the phenotype severity of the disease.

Presence of anti-modified protein antibodies in idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Studies of autoimmunity and anti-citrullinated protein antibodies (ACPA) in idiopathic pulmonary fibrosis (IPF) have been confined to investigations of anti-cyclic citrullinated peptide (anti-CCP) antibodies which utilize synthetic peptides as surrogate markers for in vivo citrullinated antigens. We studied immune activation by analysing the prevalence of in vivo anti-modified protein antibodies (AMPA) in IPF.

METHODS

We included patients with incident and prevalent IPF (N = 120), sex and smoking-matched healthy controls (HC) (N = 120) and patients with RA (N = 104). Serum (median time: 11 months [Q1-Q3: 1-28 months] from diagnosis) was analysed for presence of antibodies towards native and posttranslational modified (citrullinated [Cit, N = 25]; acetylated [Acet, N = 4] and homocitrullinated [Carb, N = 1]) peptides derived from tenascin (TNC, N = 9), fibrinogen (Fib, N = 11), filaggrin (Fil, N = 5), histone (N = 8), cathelicidin (LL37, N = 4) and vimentin (N = 5) using a custom-made peptide microarray.

RESULTS

AMPA were more frequent and in increased levels in IPF than in HC (44% vs. 27%, p < 0.01), but less than in RA (44% vs. 79%, p < 0.01). We specifically observed AMPA in IPF towards certain citrullinated, acetylated and carbamylated peptides versus HC: tenascin (Cit(2033) -TNC2025-2040 ; Cit(2197) -TNC2177-2200 ; Cit(2198) -TNC2177-2200 ), fibrinogen (Cit(38,42) -Fibα36-50 ; Cit(72) -Fibβ60-74 ) and filaggrin (Acet-Fil307-324 , Carb-Fil307-324 ). No differences in survival (p = 0.13) or disease progression (p = 0.19) between individuals with or without AMPA was observed in IPF. However, patients with incident IPF had better survival if AMPA were present (p = 0.009).

CONCLUSION

A significant proportion of IPF patients present with specific AMPA in serum. Our results suggest autoimmunity as a possible characteristic for a subgroup of IPF that may affect disease outcome.

Epicutaneous Sensitization to the Phytocannabinoid β-Caryophyllene Induces Pruritic Inflammation

In recent years, there has been increased accessibility to cannabis for recreational and medicinal use. Incidentally, there has been an increase in reports describing allergic reactions to cannabis including exacerbation of underlying asthma. Recently, multiple protein allergens were discovered in cannabis, yet these fail to explain allergic sensitization in many patients, particularly urticaria and angioedema. Cannabis has a rich chemical profile including cannabinoids and terpenes that possess immunomodulatory potential. We examined whether major cannabinoids of cannabis such as cannabidiol (CBD) and the bicyclic sesquiterpene beta-caryophyllene (β-CP) act as contact sensitizers. The repeated topical application of mice skin with β-CP at 10 mg/mL (50 µL) induced an itch response and dermatitis at 2 weeks in mice, which were sustained for the period of study. Histopathological analysis of skin tissues revealed significant edema and desquamation for β-CP at 10 mg/mL. For CBD and β-CP, we observed a dose-dependent increase in epidermal thickening with profound thickening observed for β-CP at 10 mg/mL. Significant trafficking of CD11b cells was observed in various compartments of the skin in response to treatment with β-CP in a concentration-dependent manner. Mast cell trafficking was restricted to β-CP (10 mg/mL). Mouse proteome profiler cytokine/chemokine array revealed upregulation of complement C5/5a (anaphylatoxin), soluble intracellular adhesion molecule-1 (sICAM-1) and IL-1 receptor antagonist (IL-1RA) in animals dosed with β-CP (10 mg/mL). Moreover, we observed a dose-dependent increase in serum IgE in animals dosed with β-CP. Treatment with β-CP (10 mg/mL) significantly reduced filaggrin expression, an indicator of barrier disruption. In contrast, treatment with CBD at all concentrations failed to evoke scratching and dermatitis in mice and did not result in increased serum IgE. Further, skin tissues were devoid of any remarkable features, although at 10 mg/mL CBD we did observe the accumulation of dermal CD11b cells in skin tissue sections. We also observed increased filaggrin staining in mice repeatedly dosed with CBD (10 mg/mL). Collectively, our studies indicate that repeated exposure to high concentrations of β-CP can induce dermatitis-like pathological outcomes in mice.

Non-invasive Microneedle Application Increases Ceramide and Natural Moisturizing Factors in a Reconstructed Human Skin Model

Recently, microneedling as a cosmetic product has attracted attention as one way to improve skin barrier function and moisturizing function to reduce wrinkle formation. However, some cases of erythema and edema have been reported as side effects. In order to develop safer microneedle cosmetics, we investigated whether microneedles can improve skin barrier function and moisturizing function even when applied in a non-invasive manner that does not penetrate the stratum corneum. We established the condition of non-penetrating microneedle application on reconstructed human full-thickness skin models and examined the effect on the skin models when microneedles were applied under this condition. Microneedle application increased the gene expression of serine palmitoyltransferase long chain base subunit (SPTLC) 3, filaggrin, and transglutaminase 1. The amount of ceramide produced by SPTLC was also increased by microneedle application. Gene expression of filaggrin-degrading enzymes and the amount of free amino acids, a product of filaggrin degradation, were also increased by microneedling. These results suggest that non-invasive microneedle application can improve skin barrier function and moisturizing function by increasing the amount of ceramide and natural moisturizing factors.

Kaempferol therapy improved MC903 induced-atopic dermatitis in a mouse by suppressing TSLP, oxidative stress, and type 2 inflammation

BACKGROUND

Atopic dermatitis is a common skin disease caused by genetic susceptibility, environmental factors, immune response, and skin barrier dysfunction. Kaempferol is a natural flavonoid widely found in tea, vegetables, and fruits and has been reported to have excellent anti-inflammation activity. However, the therapeutic effect of kaempferol on atopic dermatitis is unclear.

OBJECTIVE

This study aimed to elucidate the effect of kaempferol on skin inflammation in atopic dermatitis.

METHODS

The suppressive effect of kaempferol administration on skin inflammation was examined using MC903-induced atopic dermatitis-like skin inflammation mouse model. Quantification of skin dermatitis and transepidermal water loss was performed. A histopathological study was performed to examine thymic stromal lymphopoietin expression, cornified envelope proteins such as filaggrin, loricrin, and involucrin, and the numbers of infiltrating inflammatory cells, including lymphocytes, macrophages, and mast cells in the dermatitis area. The expressions of IL-4 and IL-13 were investigated by qPCR and flow cytometry analysis using skin tissues. The expression of HO-1 was investigated by western blot and qPCR.

RESULTS

Kaempferol therapy significantly suppressed MC903-induced dermatitis, TEWL, TSLP, and HO-1 expression, and infiltration of inflammatory cells. Kaempferol therapy improved the decreased expressions of filaggrin, loricrin, and involucrin in MC903-induced dermatitis skin site. The expressions of IL-4, and IL-13 were partially decreased in kaempferol-treated mice.

CONCLUSION

Kaempferol might improve MC903-induced dermatitis via suppression of type 2 inflammation and improvement of barrier dysfunction by inhibition of TSLP expression and oxidative stress. Kaempferol might have the potential to be a new treatment for atopic dermatitis.

Cycloastragenol exerts protective effects against UVB irradiation in human dermal fibroblasts and HaCaT keratinocytes

BACKGROUND

Cycloastragenol (CAG) is a triterpene aglycone of astragaloside IV that possesses various pharmacological actions including improving telomerase activity, inhibiting inflammation and cell proliferation, inducing apoptosis.

OBJECTIVE

CAG has also shown effect to significantly improve the appearance of aging skin but, its molecular mechanism of protective effect against UVB induced-damage have not been elucidated. We investigated the potential effect of CAG on UVB wrinkle promoting activities and skin-moisturizing effects in human dermal fibroblasts (HDF) and HaCaT keratinocytes.

METHODS

After UVB irradiation or H2O2 treatment, the levels of matrix metalloproteinases (MMPs) and ROS generation were measured in CAG-treated HDF cells. In addition, after UVB irradiation, hyaluronic acid and skin hydration factors (filaggrin and SPT) were also analyzed in CAG (0-0.5-1-2 µM)-treated HDF and HaCaT cells.

RESULTS

We found that CAG caused a significant decrease in the levels of UVB-induced MMP-1, MMP-9, MMP-13 and ROS generation, also increased UVB-damaged Collagen Ⅰ. We also noted that CAG increased cell viability and can regulate MMP-1, MMP-9, MMP-13and Collagen Ⅰ in H2O2-damaged HDF cells. Moreover, we noticed that CAG effectively enhanced levels of hyaluronic acid and expression of skin hydration factors (filaggrin and serine palmitoyltransferase (SPT)) in UVB-damaged HDF and HaCaT cells.

CONCLUSION

This is first report indicating that CAG can exhibit protective effect against UVB and H2O2-induced damages and can contribute in maintenance of healthy skin.

Skin Barrier Function and Its Relationship With IL-17, IL-33, and Filaggrin in Malar Melasma

BACKGROUND

The pathogenesis of melasma remains unclear. Interleukin (IL)-17, a proinflammatory mediator, disturbs barrier function. Filaggrin (FLG) is a protein involved in epidermal barrier homeostasis and may be affected by IL-17 and IL-33.

OBJECTIVE

To evaluate epidermal barrier function in malar melasma and its association with the expression of FLG, IL-17, and IL-33.

METHODS

Twenty patients with malar melasma were included in this study. Colorimetric and transepidermal water loss (TEWL) was measured in lesional and adjacent unaffected skin at baseline and 30 minutes after barrier disruption using the tape-stripping test. Biopsies from melasma and perilesional skin were performed to evaluate the presence of FLG by immunohistochemistry, and profilaggrin, IL-17, and IL-33 expression were analyzed by reverse transcription-qualitative polymerase chain reaction.

RESULTS

After the stripping test, the erythema and TEWL values were higher in the melasma than in the unaffected skin ( P = 0.01). Thirty minutes later, TEWL diminished, but it remained higher than in the perilesional skin. Profilaggrin increased as TEWL gradually decreased (R = -0.68, P = 0.04). FLG and IL-17 were higher in the melasma than in the perilesional skin ( P = 0.003). IL-17 and profilaggrin expression were positively associated (R = 0.60, P = 0.04). IL-33 expression was higher in the adjacent normal skin than in the melasma ( P = 0.01).

CONCLUSION

This study found subclinical inflammation in the skin adjacent to the melasma, dysfunction of the epidermal barrier in lesions associated with chronic inflammation, and an abnormal differentiation process promoting an increase in FLG. These findings highlight the need to preserve the integrity of the facial stratum corneum in these patients.

Crisaborole efficacy in murine models of skin inflammation and Staphylococcus aureus infection

Phosphodiesterase 4 (PDE4) is highly expressed in keratinocytes and immune cells and promotes pro-inflammatory responses upon activation. The activity of PDE4 has been attributed to various inflammatory conditions, leading to the development and approval of PDE4 inhibitors as host-directed therapeutics in humans. For example, the topical PDE4 inhibitor, crisaborole, is approved for the treatment of mild-to-moderate atopic dermatitis and has shown efficacy in patients with psoriasis. However, the role of crisaborole in regulating the immunopathogenesis of inflammatory skin diseases and infection is not entirely known. Therefore, we evaluated the effects of crisaborole in multiple mouse models, including psoriasis-like dermatitis, AD-like skin inflammation with and without filaggrin mutations, and Staphylococcus aureus skin infection. We discovered that crisaborole dampens myeloid cells and itch in the skin during psoriasis-like dermatitis. Furthermore, crisaborole was effective in reducing skin inflammation in the context of filaggrin deficiency. Importantly, crisaborole reduced S. aureus skin colonization during AD-like skin inflammation. However, crisaborole was not efficacious in treating S. aureus skin infections, even as adjunctive therapy to antibiotics. Taken together, we found that crisaborole reduced itch during psoriasis-like dermatitis and decreased S. aureus skin colonization upon AD-like skin inflammation, which act as additional mechanisms by which crisaborole dampens the immunopathogenesis in mouse models of inflammatory skin diseases. Further examination is warranted to translate these preclinical findings to human disease.

Torque Teno Virus in Nasopharyngeal Aspirate of Children With Viral Respiratory Infections

BACKGROUND

Torque teno virus (TTV) is a ubiquitous anellovirus responsible for persistent infections and is considered a marker of immune function. The role of TTV as a facilitator of respiratory infections (RIs) is unknown.

OBJECTIVES

Our aim was to estimate, in a prospective study, the prevalence of TTV in the nasopharyngeal aspirate (NPA) of hospitalized children <5 years old, with RIs and correlate them with outcomes and immune response.

PATIENTS AND METHODS

NPA was taken for testing of 16 respiratory viruses by reverse transcription-polymerase chain reaction (PCR), TTV PCR, and immunologic study.

RESULTS

Sixty hospitalized children with an RI were included. A total of 51/60 patients had positive common respiratory viral (CRV) identification. A total of 23/60 (38.3%) children were TTV+ in NPA. TTV+ patients had other CRVs in 100% of cases versus 78.3% in TTV- ( P = 0.029). The TTV+ patients tended to be older, have fever, and to need pediatric intensive care unit admission more often than TTV- patients. Abnormal chest radiograph was more frequent in the TTV+ patients, odds ratios 2.6 (95% CI: 1.3-5.2). The genetic expression of filaggrin (involved in epithelial barrier integrity) was lower in TTV+ patients; however, the levels of filaggrin in the NPA were increased.

CONCLUSIONS

TTV infection is common in children with RI and could be associated with abnormal imaging in radiograph, greater severity and an alteration in filaggrin gene expression and protein release.

Scleral Proteome in Noninfectious Scleritis Unravels Upregulation of Filaggrin-2 and Signs of Neovascularization

Purpose

Scleritis is a severe inflammatory ocular disorder with unknown pathogenesis. We investigated healthy sclera as well as sclera affected by noninfectious scleritis for differentially expressed proteins using a mass spectrometry approach.

Methods

We collected scleral samples of enucleated eyes due to severe noninfectious scleritis (n = 3), and control scleral tissues (n = 5), all exenterated eyes for eyelid carcinomas (n = 4), or choroidal melanoma (n = 1) without scleral invasion. Samples were prepared for the nano liquid-chromatography mass spectrometer (LC-MS), data were analyzed using proteomics software (Scaffold), and is available via ProteomeXchange (identifier PXD038727). Samples were also stained for immuno-histopathological evaluation.

Results

Mass spectrometry identified 629 proteins within the healthy and diseased scleral tissues, whereof collagen type XII, VI, and I were the most abundantly expressed protein. Collagen type II-XII was also present. Filaggrin-2, a protein that plays a crucial role in epidermal barrier function, was found upregulated in all scleritis cases. In addition, other epithelial associated proteins were upregulated (such as keratin 33b, 34, and 85, epiplakin, transglutaminase-3, galectin 7, and caspase-14) in scleritis. Further, upregulated proteins involved in regulation of the cytoskeleton (vinculin and myosin 9), and housekeeping proteins were found (elongation factor-2 and cytoplasmic dynein 1) in our study. Upregulation of filaggrin-2 and myosin-9 was confirmed with immunohistochemistry, the latter protein showing co-localization with the endothelial cell marker ETC-related gene (ERG), indicating neovascularization in scleral tissue affected by scleritis.

Conclusions

We found upregulation of filaggrin-2 and signs of neovascularization in scleral tissue of patients with noninfectious scleritis. Further research, ideally including more scleritis cases, is needed to validate our findings.

Cannabidiol mediates epidermal terminal differentiation and redox homeostasis through aryl hydrocarbon receptor (AhR)-dependent signaling

BACKGROUND

Cannabidiol, a non-psychoactive phytocannabinoid, has antioxidant and anti-inflammatory activity in keratinocytes. However, the signaling pathway through which cannabidiol exerts its effect on keratinocytes or whether it can modulate keratinocyte differentiation has not been fully elucidated yet.

OBJECTIVE

We investigated whether cannabidiol modulates epidermal differentiation and scavenges reactive oxygen species through the aryl hydrocarbon receptor (AhR) in keratinocytes and epidermal equivalents.

METHODS

We investigated the cannabidiol-induced activation of AhR using AhR luciferase reporter assay, qRT-PCR, western blot, and immunofluorescence assays. We also analyzed whether keratinocyte differentiation and antioxidant activity are regulated by cannabidiol-induced AhR activation.

RESULTS

In both keratinocytes and epidermal equivalents, cannabidiol increased both the mRNA and protein expression of filaggrin, involucrin, NRF2, and NQO1 and the mRNA expression of the AhR target genes, including CYP1A1 and aryl hydrocarbon receptor repressor. Additionally, cannabidiol showed antioxidant activity that was attenuated by AhR knockdown or co-administration with an AhR antagonist. Moreover, cannabidiol increased the ratio of OVOL1/OVOL2 mRNA expression, which is a downstream regulator of AhR that mediates epidermal differentiation. In addition to increased expression of barrier-related proteins, cannabidiol-treated epidermal equivalent showed a more prominent granular layer than the control epidermis. The increased granular layer by cannabidiol was suppressed by the AhR antagonist.

CONCLUSION

Cannabidiol can be a modulator of the AhR-OVOL1-filaggrin axis and AhR-NRF2-NQO1 signaling, thus indicating a potential use of cannabidiol in skin barrier enhancement and reducing oxidative stress.

Uncommon variants in FLG2 and TCHHL1 are associated with remission of atopic dermatitis in a large longitudinal US cohort

Atopic dermatitis (AD) is a relapsing inflammatory skin disease; filaggrin (FLG) variation has been consistently associated with its pathogenesis. Filaggrin-2 (FLG2) and trichohyalin-like-1 (TCHHL1) are members of the same protein family (S100 fused-type proteins), are similar in structure to FLG, and may be involved in AD pathogenesis. We sought to evaluate the association between variation in FLG2, TCHHL1 and AD remission. We sequenced FLG2 and TCHHL1 in a longitudinal AD cohort using targeted capture-based massively parallel sequencing. Association between individual alleles and AD remission was evaluated with generalized estimating equations for binary outcomes. Association between groups of alleles and AD remission was evaluated using a genetic algorithm to group alleles. We identified two loss-of-function (LoF) mutations in FLG2 (Ser2377Ter, Arg2207Ter) and 2 LoF mutations in TCHHL1 (Gln656Ter, Gln294Ter), none of which were associated with AD remission. Common (MAF > 5%) alleles in FLG2 were similarly unassociated with AD. No common alleles in TCHHL1 were associated with AD remission after multiple testing correction. Among self-described whites, a group of 34 uncommon alleles in FLG2 were associated with increased AD remission (OR 7.64e17; 95% CI 4.41e17-1.32e18; adjusted p < 1.0e-16). Twelve uncommon alleles in TCHHL1 trended toward association with increased AD remission (OR 23.46; 95% CI 7.07-77.89; adjusted p = 0.064). Among self-described African Americans, 13 uncommon FLG2 alleles were associated with increased AD remission (OR 21.01; 95% CI 11.90-37.09; adjusted p < 1.0e-16). No TCHHL1 uncommon allele groups were associated with AD remission among African Americans. Our study supports the role of uncommon alleles in FLG2 and TCHHL1 in AD pathogenesis.

Filaggrin loss-of-function mutations are associated with persistence of egg and milk allergy

BACKGROUND

A genetic defect in the epidermal barrier protein filaggrin plays a major role in the etiology of eczema and associated allergic airways diseases. However, it is still controversial to what extend loss-of-function (LOF) mutations in the filaggrin gene (FLG) contribute to the development and persistence of food allergies.

OBJECTIVE

We tested association of FLG LOF mutations with allergic reactions to diverse foods and investigated their potential effect on the persistence of early food allergies.

METHODS

We recruited 890 children with challenge-proven food allergy for the German Genetics of Food Allergy Study (GOFA). Longitudinal data were available for 684 children. All children were clinically characterized, including their allergic responses to specific foods, and genotyped for the four most common LOF mutations in FLG; R501X, 2282del4, R2447X, and S3247X. Associations between FLG mutations and food allergies were analyzed by logistic regression using the German Multicenter Allergy Study cohort as control population.

RESULTS

FLG mutations were associated with allergies to diverse foods including hen's egg (HE), cow's milk (CM), peanut, hazelnut, fish, soy, cashew, walnut, and sesame with similar risk estimates. Effects remained significant after adjusting for the eczema status. Interestingly, FLG mutations increased the risk of a persistent course of HE and CM allergy.

CONCLUSION

Using the gold standard for food allergy diagnosis, we demonstrate that FLG LOF mutations confer a risk of any food allergy independent of eczema. They predispose to the persistence of HE and CM allergy and should be considered in the assessment of tolerance development.

Revisiting the Roles of Filaggrin in Atopic Dermatitis

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

New ribotype Clostridioides difficile from ST11 group revealed higher pathogenic ability than RT078

Clostridioides difficile is the predominant antibiotic-associated enteropathogen associated with diarrhoea or pseudomembranous colitis in patients worldwide. Previously, we identified C. difficile RT078 isolates (CD21062) from elderly patients in China, including two new ribotype strains (CD10010 and CD12038) belonging to the ST11 group, and their genomic features were also investigated. This study compared sporulation, spore germination, toxin expression, flagellar characteristics, and adhesion among these strains in vitro and analysed their pathogenic ability in vivo using animal models. The results showed sporulation and spore germination did not significantly differ among the three C. difficile strains. CD10010 and CD12038 showed higher transcriptional levels of toxins until 48 h; thereafter, the transcriptional levels of toxins remained constant among RT078, CD10010, and CD12038. RT078 showed a loss of flagellum and its related genes, whereas CD12038 showed the highest motility in vitro. Both CD10010 and CD12038 initially showed flg phase OFF, and the flagellar switch reversed to phase ON after 48 h in swim agar. Flagellar proteins and toxins were both upregulated when flg phase OFF changed to flg phase ON status, enhancing their pathogenic ability. CD12038 showed the highest adhesion to Hep-2 cells. Histopathology and inflammation scores demonstrated that CD12038 caused the most severe tissue damage and infection in vivo. The new ribotype strains, particularly CD12038, exhibit higher pathogenic ability than the typical RT078 strain, both in vitro and in vivo. Therefore, more attention should be paid to this new C. difficile strain in epidemiological research; further studies are warranted.

Filaggrin Expression in the Lid Margin During Contact Lens Wear

AIM

To investigate the expression of the keratinization-related protein, filaggrin, in the lid margin epithelium of contact lens (CL) wearers compared with nonwearers.

METHODS

This was a cross-sectional study of 100 individuals with different exposures to CL wear: short, moderate, and long experience; previous CL wearers; and nonwearers as controls. Impression cytology samples were collected from the lid wiper (LW) area of the central upper lid margin. After fixing, an equal, random sample was selected from each group (n=13) for immunocytochemistry analysis using antihuman primary anybody (mouse filaggrin), then stained with secondary antibody (fluorescein isothiocyanate-conjugated donkey anti-mouse immunoglobulin G horseradish peroxidase) to detect filaggrin. Imaging was performed with the 3i-Vivo 2-photon microscope equipped with a Zeiss 20×-objective and SlideBook-reader software.

RESULTS

Sixty-five samples from 65 participants (37 women; mean age±SD: 25.1±4.1 years) were collected. Filaggrin was detected in all 65 randomly selected immunostained marginal epithelium samples. All samples were similar in showing patchy areas of filaggrin immunostaining, regardless of CL wear, symptoms or epithelium morphology. Because the filaggrin immunostaining showed similar patterns across almost all the observed samples, comparison between subject groups was impractical. The presence of filaggrin in the healthy LW was additionally confirmed by an independent laboratory.

CONCLUSION

Filaggrin expression seems to be a normal part of epithelial cell differentiation in the lid margin and may not be a useful keratinization/stress biomarker in the marginal epithelium. Investigating other keratinization biomarkers that are not detected in the normal mucocutaneous junction/LW may help to understand the keratinization nature of LW epithelium changes in CL wearers.

Non-IgE Mediated Hypersensitivity to Food Products or Food Intolerance—Problems of Appropriate Diagnostics

The diagnosis of food intolerance is tricky due to the different etiologies of adverse reactions. There is also a lack of clear rules for interpreting alternative tests used to diagnose these problems. The analyses of IgG4 concentration in serum or cytotoxic tests became the basis of elimination diets. However, it can result in nutritional deficiencies and loss of tolerance to eliminated foods. Our study aimed to assess the necessity of food elimination in four cases with food intolerance symptoms based on alternative diagnostic tests. Four patients without food allergies, who manifested diverse clinical symptoms after food, were presented due to the following factors: clinical history, diagnostic tests, elimination diet, and filaggrin gene (FLG) mutation. It was found that higher IgG4 levels against foods and higher cytotoxic test values are not clinically relevant in each of the studied individuals. They should not be decisive for the elimination of food products. The study of FLG-SNVs revealed the association of some clinical symptoms in patients with hypersensitivity to several food allergens and reported genetic variants in the FLG gene.

Aspergillus oryzae-Fermented Wheat Peptone Enhances the Potential of Proliferation and Hydration of Human Keratinocytes through Activation of p44/42 MAPK

Identifying materials contributing to skin hydration, essential for normal skin homeostasis, has recently gained increased research interest. In this study, we investigated the potential benefits and mechanisms of action of Aspergillus oryzae-fermented wheat peptone (AFWP) on the proliferation and hydration of human skin keratinocytes, through in vitro experiments using HaCaT cell lines. The findings revealed that compared to unfermented wheat peptone, AFWP exhibited an improved amino acid composition, significantly (p < 0.05) higher DPPH scavenging capability and cell proliferation activity, and reduced lipopolysaccharide-induced NO production in RAW 264.7 cells. Furthermore, we separated AFWP into eleven fractions, each ≤2 kDa; of these, fraction 4 (AFW4) demonstrated the highest efficacy in the cell proliferation assay and was found to be the key component responsible for the cell proliferation potential and antioxidant properties of AFWP. Additionally, AFW4 increased the expression of genes encoding natural moisturizing factors, including filaggrin, transglutaminase-1, and hyaluronic acid synthase 1–3. Furthermore, AFW4 activated p44/42 MAPK, but not JNK and p38 MAPK, whereas PD98059, a p44/42 MAPK inhibitor, attenuated the beneficial effects of AFW4 on the skin, suggesting that the effects of AFW4 are mediated via p44/42 MAPK activation. Finally, in clinical studies, AFW4 treatment resulted in increased skin hydration and reduced trans-epidermal water loss compared with a placebo group. Collectively, these data provide evidence that AFW4 could be used as a potential therapeutic agent to improve skin barrier damage induced by external stresses.

Construction of a high fidelity epidermis-on-a-chip for scalable in vitro irritation evaluation

3D skin equivalents have been increasingly used in the pharmaceutical and cosmetic industries, but the troublesome operation procedure and low throughput restricted their applications as in vitro safety evaluation models. Organ-on-a-chip, an emerging powerful tool in tissue/organ modeling, could be utilized to improve the function of the skin model compared with that of traditional static skin models, as well as innovate an automatic and modular way for construction or detection. In this research, we grew and differentiated human keratinocytes within a microfluidic chip to construct an integrated epidermis-on-a-chip (iEOC) system, which is specially designed to integrate multi-culture units with integrated bubble removal structures as well as trans-epithelial electrical resistance (TEER) electrodes for barrier function detection in situ. After 14 days of culture at the air-liquid interface (ALI), the constructed epidermis-on-a-chip demonstrated histological features similar to those observed in normal human epidermis: a proliferating basal layer and differentiating spinous, granular, and cornified layers, especially the TEER value reached 3 kΩ cm² and prevented more than 99% of Cascade Blue-607 Da permeation owing to the enhanced barrier function. Further immunofluorescence analysis also indicated typical keratin expression including keratin-14, keratin-10, loricrin, involucrin, and filaggrin. With the TEER monitoring integration in the chip, it could be convenient for scale-up high-quality epidermis-on-chip fabrication and correlated investigation. Additionally, the iEOC can distinguish all the 10 known toxins and non-toxins in irritation measurement by MTT assay, which is consistent with animal testing according to the OECD. Preliminarily detection of irritation responses like inflammatory cytokines also predicted different irritation reactions. This high fidelity epidermis-on-a-chip could be a potential alternative in in vitro skin irritation evaluation. This microchip and automated microfluidic systems also pave the way for scalable testing in multidisciplinary industrial applications.

FAK Shutdown: Consequences on Epithelial Morphogenesis and Biomarker Expression Involving an Innovative Biomaterial for Tissue Regeneration

By employing an innovative biohybrid membrane, the present study aimed at elucidating the mechanistic role of the focal adhesion kinase (FAK) in epithelial morphogenesis in vitro over 4, 7, and 10 days. The consequences of siRNA-mediated FAK knockdown on epithelial morphogenesis were monitored by quantifying cell layers and detecting the expression of biomarkers of epithelial differentiation and homeostasis. Histologic examination of FAK-depleted samples showed a significant increase in cell layers resembling epithelial hyperplasia. Semiquantitative fluorescence imaging (SQFI) revealed tissue homeostatic disturbances by significantly increased involucrin expression over time, persistence of yes-associated protein (YAP) and an increase of keratin (K) 1 at day 4. The dysbalanced involucrin pattern was underscored by ROCK-II^Ser1366 activity at day 7 and 10. SQFI data were confirmed by quantitative PCR and Western blot analysis, thereby corroborating the FAK shutdown-related expression changes. The artificial FAK shutdown was also associated with a significantly higher expression of filaggrin at day 10, sustained keratinocyte proliferation, and the dysregulated expression of K19 and vimentin. These siRNA-induced consequences indicate the mechanistic role of FAK in epithelial morphogenesis by simultaneously considering prospective biomaterial-based epithelial regenerative approaches.

Protective Effect of Potentilla glabra in UVB-Induced Photoaging Process

Maintaining skin homeostasis is one of the most important factors for skin health. UVB-induced skin photoaging is a difficult problem that has negative impacts on skin homeostasis. So far, a number of compounds have been discovered that improve human skin barrier function and hydration, and are thought to be effective ways to protect skin homeostasis. Potentilla glabra var. mandshurica (Maxim.) Hand.-Mazz. Ethanol Extract (Pg-EE) is a compound that has noteworthy anti-inflammatory properties. However, its skin-protective effects are poorly understood. Therefore, we evaluated the capacity of Pg-EE to strengthen the skin barrier and improve skin hydration. Pg-EE can enhance the expression of filaggrin (FLG), transglutaminase (TGM)-1, hyaluronic acid synthase (HAS)-1, and HAS-2 in human keratinocytes. Moreover, Pg-EE down-regulated the expression of pro-inflammatory cytokines and up-regulated the production of FLG, HAS-1, and HAS-2 suppressed by UVB through inhibition of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) pathways. Given the above, since Pg-EE can improve skin barrier, hydration and reduce the UVB-induced inflammation on skin, it could therefore be a valuable natural ingredient for cosmetics or pharmaceuticals to treat skin disorders.