Significance of stress keratin expression in normal and diseased epithelia

Proteomic Analysis of Invasive Breast Cancer Cells Treated with CBD Reveals Proteins Associated with the Reversal of Their Epithelial-Mesenchymal Transition Induced by IL-1β

Cannabidiol (CBD) has shown promise in treating cancers with an inflammatory microenvironment. Although it has been demonstrated that IL-1β induces epithelial-mesenchymal transition (EMT) of MCF-7 cells and CBD reverts this process, in restoring the epithelial non-invasive phenotype, there is limited understanding of how this cannabinoid regulates these processes. In this work, MCF-7 cells were induced to adopt an aggressive phenotype (6D cells), which was reversed by CBD. Then, protein expression was analyzed by mass spectrometry to compare 6D vs. MCF-7 cells and 6D+CBD vs. 6D cells proteomes. Novel proteins associated with EMT and CBD signaling were identified. Twenty-four of them were oppositely regulated by IL-1β and CBD, suggesting new points of crosstalk between the IL-1β and CBD signaling pathways. From the data, two protein networks were constructed: one related to EMT with 58 up-regulated proteins and another with 21 related to CBD signaling. The first one showed the proteins BRCA1, MSN, and CORO1A as the key axis that contributes to the establishment of a mesenchymal phenotype. In the CBD signaling, the key axis was formed by SUPT16H, SETD2, and H2BC12, which suggests epigenetic regulation by CBD in the restoration of an epithelial phenotype of breast cancer cells, providing new targets for anticancer therapy.

Deciphering the Transcriptomic Complexity of Yak Skin Across Different Ages and Body Sites

Differences in skin and hair phenotypes between the scapular and ventral regions of yaks (Bos grunniens) are obvious and become more prominent with age. However, the genetic mechanism that causes differences in yak skin at different ages has not been reported. In this study, we investigated the transcriptomic profile of yak skin across different ages (0.5 years, 2.5 years, and 4.5 years) and body sites (scapular and ventral regions). Differential gene expression analysis was initially conducted to explore the transcriptomic differences in skin at different ages and different body sites. Subsequently, weighted gene co-expression network analysis (WGCNA) was employed to analyze the transcriptomic data comprehensively. The results showed that, among all comparison groups, the Y2.5_S vs. Y2.5_V group (regional comparison) exhibited the highest number of DEGs, with 491 genes (179 upregulated and 312 downregulated), followed by the Y2.5_V vs. Y0.5_V group (age comparison), which had 370 DEGs (103 upregulated and 267 downregulated). DEGs such as IGF2BP3, ADCY8, FOSL1, and S100A8 were found in all comparison groups of different ages, and multiple members of the HOX gene family including HOXC10, HOXA9, HOXA6, HOXB9, and HOXB6 were differentially expressed in comparison groups at different sites. Functional enrichment analysis showed that there were more obvious differences in immune function between different ages of skin and more obvious differences in endocrine function between different parts of skin. WGCNA revealed that genes related with immunity such as GLYATL2, ACSL5, and SPDEF were the core genes of the co-expression module associated with the scapula region, and multiple genes related to hair follicle development such as FOXN1, OVOL1, DLX3, HOXC13, and TCHH were found to be the hub genes of the co-expression module associated with the ventral region. Overall, our study provides valuable insights into the transcriptomic complexity of yak skin across different ages and body sites. The differential gene expression patterns and co-expression network modules identified in this study lay the foundation for further research on skin biology and adaptation mechanisms in yaks.

Abrocitinib versus dupilumab: Impact on skin barrier function and proteomics in atopic dermatitis

BACKGROUND

The comparative impact of dupilumab and abrocitinib on skin barrier function and associated proteomics in atopic dermatitis (AD) remains not fully identified.

OBJECTIVE

To investigate the effects of dupilumab versus abrocitinib on skin barrier function and proteomic profiles in AD.

METHODS

In this study, 33 patients with moderate-to-severe AD were randomized into 2 groups: 16 received dupilumab and 17 received abrocitinib. Clinical outcomes and skin barrier parameters (transepidermal water loss and hydration) were assessed at baseline, 4 weeks, and 12 weeks. Skin tape strips were collected for four-dimensional data-independent acquisition-based proteomics.

RESULTS

Both therapies improved skin barrier function, with abrocitinib achieving superior reductions in transepidermal water loss in nonlesional skin (P = .0168). Proteomic analysis revealed differentially expressed proteins predominantly associated with ceramide metabolism, neurobiology, and keratinocyte biology in AD. Key potential biomarkers were identified: arginase 1 and proteasome subunit beta type-6 in lesional skin, alongside grancalcin and phospholipase D3 in nonlesional skin. Abrocitinib enhanced the expression of crucial barrier proteins, such as filaggrin-2 and loricrin, in lesional skin-an effect not observed with dupilumab.

LIMITATIONS

The cohort size is small.

CONCLUSION

While both abrocitinib and dupilumab effectively restore skin barrier function in AD, they exhibit distinct proteomic impacts.

Expression Distribution of Keratins in Normal and Pathological Corneas and the Regulatory Role of Krt17 on Limbal Stem Cells

Purpose

This study aimed to compare variations in keratins (KRTs), particularly stress KRTs, under normal and pathological conditions, with a specific focus on investigating the role of KRT17.

Methods

This research examined changes in KRT and limbal stem cell (LSC) markers in normal and various pathological corneas using mRNA and proteomic sequencing data alongside single-cell sequencing data from normal mouse corneas. The effects of the Krt17 recombinant protein and specific small interfering RNA on the clonal formation and proliferation of human limbal epithelial cells (HLECs) were investigated. mRNA sequencing was conducted on Krt17 knockdown HLECs, and the findings were validated using qPCR, immunofluorescence staining, neutrophil chemotaxis, and herpes simplex virus 1 infection assay. The STRING database was used to predict Krt17's interacting proteins.

Results

Various KRTs in the corneal epithelia exhibited differences in expression levels and patterns. Under pathological conditions, stress KRTs Krt17 and Krt16 were upregulated, while differentiation-related Krt12 was downregulated, and the expression of the LSC markers Krt17, Krt14, and IFITM3 were commonly increased. Supplementation and intervention experiments confirmed that Krt17 promotes clonal formation and proliferation in HLECs. Krt17 knockdown resulted in the upregulation of genes related to inflammation and defense responses, while downregulating molecules associated with differentiation pathways. Krt17 knockdown promoted neutrophil chemotaxis and alleviated herpes simplex virus 1 infection in HLECs.

Conclusions

KRTs play a crucial role in the homeostasis and pathological regulation of the corneal epithelium. The stress Krt17 located in LSCs is involved in regulating the stemness, proliferation, and differentiation of LSCs, as well as immune and defense responses.

Keratin 15 promotes a progenitor cell state in basal keratinocytes of skin epidermis

The type I intermediate filament proteins keratin 14 (K14) and keratin 15 (K15) are common to all complex epithelia. K14 is highly expressed by progenitor keratinocytes, in which it provides essential mechanical integrity and gates keratinocyte entry into differentiation by sequestering YAP1, a transcriptional effector of Hippo signaling, to the cytoplasm. K15 has long been used as a marker of hair bulge stem cells though its specific role in skin epithelia is unknown. Here we show that the lack of two biochemical determinants, a cysteine residue within the stutter motif of the central rod domain and a 14-3-3 binding site in the N-terminal head domain, renders K15 unable to effectively sequester YAP1 in the cytoplasm. We combine insight obtained from cell culture and transgenic mouse models with computational analyses of transcriptomics data and propose a model in which the K15:K14 ratio promotes a progenitor state and antagonizes differentiation in keratinocytes of the epidermis.

Cross-sectional study of proteomic differences between moderate and severe psoriasis

Although an ongoing understanding of psoriasis vulgaris (PV) pathogenesis, little is known about the proteomic differences between moderate and severe psoriasis. In this cross-sectional study, we evaluated the proteomic differences between moderate and severe psoriasis using data-independent acquisition mass spectrometry (DIA-MS). 173 differentially expressed proteins (DEPs) were significantly differentially expressed between the two groups. Among them, 85 proteins were upregulated, while 88 were downregulated (FC ≥ ± 1.5, P < 0.05). Eighteen DEPs were mainly enriched in the IL - 17 signalling pathway, Neutrophil extracellular trap formation, Neutrophil degranulation and NF - kappa B signalling pathway, which were associated with psoriasis pathogenesis. Ingenuity pathway Analysis (IPA) identified TNF and TDP53 as the top upstream up-regulators, while Lipopolysaccharide and YAP1 were the top potential down-regulators. The main active pathways were antimicrobial peptides and PTEN signalling, while the inhibitory pathways were the neutrophil extracellular trap pathway, neutrophil degranulation, and IL-8 signalling. 4D-parallel reaction monitoring (4D-PRM) suggested that KRT6A were downregulated in severe psoriasis. Our data identify Eighteen DEPs as biomarkers of disease severity, and are associated with IL - 17 signalling pathway, Neutrophil extracellular trap formation, NF - kappa B signalling pathway, and defence response to the bacterium. Targeting these molecules and measures to manage infection may improve psoriasis's severity and therapeutic efficacy.

Physiological Responses to Acute Heat Stress in Rohu, Labeo rohita: Insights from Liver Proteomics

Heat stress is a major problem in aquaculture species, causing changes in physiology such as decreased feed intake, growth rate, reproduction, and internal cellular damage, thereby affecting fish's health. The effects of an acute heat stress simulating a daily rise and fall in temperature on summer days were evaluated in the liver proteome of rohu (Labeo rohita) fingerlings in the present study. The fish maintained at 30 °C were gradually exposed to a higher temperature of 36 °C at an increment rate of 1 °C per 1.5 h, and after 3 h at that temperature, it was gradually reduced to 30 °C. The liver tissue samples were collected at 5 am, 5 pm, and 5 am the next day from the exposed and control fish. Protein samples were prepared from the liver tissues, and the extracted proteins were compared using 2-dimensional (2D) gel electrophoresis (2DGE) and mass spectrometry (MS) using a MALDI-TOF/TOF mass spectrometer. A total of 44 differentially expressed protein spots were visualized in 2D gel analysis from heat stress exposed fish at three time points, out of which 21 proteins including one hypothetical protein could be identified by MS. The abundance of five selected differentially expressed proteins (DEPs) was validated using qPCR. The majority of DEPs were found to be involved primarily in lipid, protein and energy metabolism, immune system regulation, cytoskeletal stability, and ROS management. The findings of this study would help in the development of strategies to mitigate heat stress in L. rohita.

Transcriptomic Analyses Predict Enhanced Metabolic Activity and Therapeutic Potential of mTOR Inhibitors in Acne-Prone Skin

Current acne therapies center on preventing new lesions in patients with acne. These therapies were historically found to be beneficial yet were chosen without knowledge of the specific changes in the skin that favor lesion development. A major challenge in developing new treatments is the incomplete understanding of nonlesional (NL), acne-prone skin's molecular characteristics. To address this, we compared RNA-sequencing data from NL skin of 49 patients with acne (denoted as NL acne [NLA]) with those from 19 healthy controls with no acne history. We found 77 differentially expressed genes in NLA (log fold change > 1; P < .05), including genes associated with innate immunity and epidermal barrier function. Notably, K RT 6C, K RT 16, S100A8, S100A9, and lactotransferrin were upregulated, and LCE4A, LCE6A, and CTSE were downregulated. Gene set enrichment analysis revealed that metabolic pathways were enriched in NLA skin, whereas keratinization was negatively enriched. To identify compounds that could shift the gene expression signature of NLA skin toward healthy control skin, we performed connectivity mapping with the Library of Integrated Network-Based Signatures. We identified 187 compounds, particularly mTOR inhibitors, that could potentially normalize the gene expression profile of acne-prone skin to that of healthy skin. Our findings indicate that NLA skin has distinct differences in epidermal differentiation, cellular metabolism, and innate immunity that may promote lesion formation and suggest that mTOR inhibitors could restore NLA skin toward a healthier state, potentially reversing the predisposition to lesion development.

The Identification of Proteomic Signatures Associated with Alkaline Tolerance in the Skin Mucus of Crucian Carp (Carassius auratus)

The skin is covered by a protective mucus layer, which is essential to the innate defense mechanism of fish. Investigating the response of skin mucus to various toxic stresses is crucial for enhancing its ability to tackle environmental challenges and developing strategies to mitigate toxic effects. Alkalinity stress assays (50 mmol/L NaHCO3) were conducted on crucian carp (Carassius auratus) from Lake Dali Nur (pH = 9.6) and Ping Xiang red crucian carp from freshwater (pH = 7) over 7 days. The expression of skin mucous proteins was analyzed using the liquid chromatography (LC)-spectrometry (MS)/MS Analysis-Data-independent acquisition (DIA) mode. A total of 12,537 proteins were identified across 20 samples from four groups, with 12,025 quantified. In the alkaline water population, high alkali stress resulted in the up-regulation of 139 proteins and the down-regulation of 500 proteins. In contrast, the freshwater population showed an increase in 112 proteins and a decrease in 120; both populations had a total of 23 genes up-regulated and 21 down-regulated. The protein regulatory network for the alkaline water group included 3146 pairwise interactions among 464 nodes, with only 20 being differentially expressed proteins. Conversely, the freshwater group's network comprised just 1027 specific interactions across 337 nodes, with 6 corresponding to differentially expressed proteins. A common protein regulatory network responding to high alkali stress was extracted and visualized for both populations. Based on their regulatory relationships and expression levels, these proteins are hypothesized to play similar roles under high alkali stress. Notably, the alpha-globin fragment and keratin type I cytoskeletal 13-like proteins showed markedly up-regulated expression, with the alpha-globin fragment increasing nearly a thousandfold from an extremely low level. This suggests it could serve as a potential biomarker for alkali tolerance, warranting further investigation.

Single-cell and spatial transcriptomics of vulvar lichen sclerosus reveal multi-compartmental alterations in gene expression and signaling cross-talk

Vulvar diseases are a critical yet often neglected area of women's health, profoundly affecting patients' quality of life and frequently resulting in long-term physical and psychological challenges. Lichen sclerosus (LS) is a chronic inflammatory skin disorder that predominantly affects the vulva, leading to severe itching, pain, scarring, and an increased risk of malignancy. Despite its profound impact on affected individuals, the molecular pathogenesis of vulvar LS (VLS) is not well understood, hindering the development of FDA-approved therapies. Here, we utilize single-cell and spatial transcriptomics to analyze lesional and non-lesional skin from VLS patients, as well as healthy control vulvar skin. Our findings demonstrate histologic, cellular, and molecular heterogeneities within VLS, yet highlight unifying molecular changes across keratinocytes, fibroblasts, immune cells, and melanocytes in lesional skin. They reveal cellular stress and damage in fibroblasts and keratinocytes, enhanced T cell activation and cytotoxicity, aberrant cell-cell signaling, and increased activation of the IFN, JAK/STAT, and p53 pathways in specific cell types. Using both monolayer and organotypic culture models, we also demonstrate that knockdown of select genes, which are downregulated in VLS lesional keratinocytes, partially recapitulates VLS-like stress-associated changes. Collectively, these data provide novel insights into the pathogenesis of VLS, identifying potential biomarkers and therapeutic targets for future research.

Keratins 6, 16, and 17 in Health and Disease: A Summary of Recent Findings

Keratins 6, 16, and 17 occupy unique positions within the keratin family. These proteins are not commonly found in the healthy, intact epidermis, but their expression increases in response to damage, inflammation, and hereditary skin conditions, as well as cancerous cell transformations and tumor growth. As a result, there is an active investigation into the potential use of these proteins as biomarkers for different pathologies. Recent studies have revealed the role of these keratins in regulating keratinocyte migration, proliferation, and growth, and more recently, their nuclear functions, including their role in maintaining nuclear structure and responding to DNA damage, have also been identified. This review aims to summarize the latest research on keratins 6, 16, and 17, their regulation in the epidermis, and their potential use as biomarkers in various skin conditions.

Repeated stress to the skin amplifies neutrophil infiltration in a keratin 17- and PKCα-dependent manner

Neutrophils are the first immune cells to reach inflamed sites and contribute to the pathogenesis of chronic inflammatory skin diseases. Yet, little is known about the pattern of neutrophil infiltration in inflamed skin in vivo and the mechanisms mediating their recruitment. Here, we provide insight into the dynamics of neutrophil infiltration in skin in response to acute or repeated inflammatory stress, highlighting a novel keratinocyte- and keratin 17 (K17)-dependent mechanism that regulates neutrophil recruitment to inflamed skin. We used the phorbol ester TPA and UVB, alone or in combination, to induce sterile inflammation in mouse skin. A single TPA treatment results in a neutrophil influx in the dermis that peaks at 12 h and resolves within 24 h. A subsequent TPA treatment or a UVB challenge, when applied 24 h but not 48 h later, accelerates, amplifies, and prolongs neutrophil infiltration. This transient amplification response (TAR) is mediated by local signals in inflamed skin, can be recapitulated in ex vivo culture, and involves the K17-dependent sustainment of protein kinase Cα (PKCα) activity and release of chemoattractants by stressed keratinocytes. K17 binds RACK1, a scaffold protein essential for PKCα activity. The N-terminal head domain of K17 is crucial for its association with RACK1 and regulation of PKCα activity. Analysis of RNAseq data reveals a signature consistent with TAR and PKCα activation in inflammatory skin diseases. These findings uncover a novel, keratin-dependent mechanism that amplifies neutrophil recruitment in skin under stress, with direct implications for inflammatory skin disorders.