Vitamin C Promotes Epidermal Proliferation by Promoting DNA Demethylation of Proliferation-Related Genes in Human Epidermal Equivalents

Keratinocyte differentiation is highly regulated to produce the stratified structure of the epidermis and must be balanced with cell proliferation. Our prior studies revealed that hairless mice that cannot synthesize vitamin C (VC) exhibit epidermal atrophy. VC is a cofactor for the DNA demethylation (ten-eleven translocation) enzyme, but the role of VC in DNA demethylation during keratinocyte differentiation remains unclear. In this study, we evaluated the role of VC in epigenetic regulation of epidermal proliferation and differentiation in a human epidermal equivalent model. Our findings demonstrated that intracellular VC uptake increased epidermal thickness, cell proliferation, and global levels of 5-hydroxymethylcytosine DNA. Notably, these effects of VC were attenuated by an inhibitor of the ten-eleven translocation enzyme. DNA microarray and whole-genome bisulfite sequencing analyses revealed that 12 genes related to cell proliferation were significantly upregulated by VC. Furthermore, hypomethylated DNA regions associated with these genes were revealed in the presence of VC. Collectively, our findings provide insight into how VC increases epidermal thickness by promoting keratinocyte proliferation through the DNA demethylation of proliferation-related genes. VC is a promising molecule that can be used as developing treatment for epidermal thinning, including in aging.

Regulation of epithelial growth factor receptors by the oncoprotein E5 during the HPV16 differentiation-dependent life cycle

Human papillomavirus (HPV) 16 infection initiates upon viral entry into the basal cells of the epithelium. The virus manipulates signaling pathways to complete its life cycle, which depends on cellular differentiation. The virus expresses the oncoproteins E5, E6, and E7 to promote immune evasion, cell cycle progression, apoptosis inhibition, and viral replication. The least studied viral oncoprotein is E5 (16E5), which can regulate epithelial growth factor receptor (GFR) signaling pathways. GFRs such as transforming growth factor-beta receptor (TGFBR), epidermal growth factor receptor (EGFR), and keratinocyte growth factor receptor (KGFR) have essential roles in cell growth, differentiation, and proliferation. These receptors obtain their ligands from the microenvironment, and once activated, regulate cellular behavior in the epithelium. GFRs therefore represent valuable targets for the virus to establish and maintain a cellular environment supportive of infection. The ability of 16E5 to regulate proliferation and differentiation varies through the differentiating epithelium, making it necessary to adequately describe the association between 16E5 and GFRs. Here we summarize the regulation of GFR signaling pathways by 16E5, discuss the roles of stromal growth factors, and outline unresolved questions over cellular differentiation and proliferation during the HPV life cycle.

Brigatinib can inhibit proliferation and induce apoptosis of human immortalized keratinocyte cells

Background

Brigatinib is approved in multiple countries for the treatment of patients with anaplastic lymphoma kinase (ALK)-positive non-small cell lung cancer (NSCLC). Despite its superior efficacy, the dermal toxicities caused by brigatinib cannot be overlooked. However, its underlying mechanism remains unknown.

Methods

The effects of brigatinib on the proliferation ability of human immortalized keratinocyte (HaCaT) cells were evaluated using Cell Counting Kit-8 (CCK-8) proliferation, colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) incorporation assays. The effects of brigatinib on apoptosis were detected using Annexin FITC/PI and Acridine Orange (AO) staining assays. Cell cycle was assessed with flow cytometry. An analysis of transcriptome by RNA sequencing procedures (RNA-seq) was performed to reveal the key regulatory genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to find out the biological function and related signal pathways. The expressions of amphiregulin, epiregulin and transforming growth factor alpha (TGFA) and the protein levels of Phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and Cleaved-Caspase three were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot assay.

Results

Brigatinib inhibits cell proliferation with an IC50 value of 2.9 μmol/L and significantly increases apoptosis rates. Transcriptome sequencing (RNA-seq) indicates that brigatinib could significantly downregulate the expression of amphiregulin, epiregulin and TGFA. In addition, we demonstrated that brigatinib reduced the protein expression of amphiregulin, epiregulin, TGFA, PI3K, AKT and phosphorylated AKT (p-AKT).

Conclusion

This study confirms the inhibition of HaCaT cells growth and progression by brigatinib and highlights the potential value of the PI3K/AKT pathway as a therapeutic target for brigatinib-induced dermal toxicities.

JAK-STAT1 as therapeutic target for EGFR deficiency-associated inflammation and scarring alopecia

The hair follicle stem cell niche is an immune-privileged microenvironment, characterized by reduced antigen presentation, thus shielding against permanent immune-mediated tissue damage. In this study, we demonstrated the protective role of hair follicle-specific epidermal growth factor receptor (EGFR) against scarring hair follicle destruction. Mechanistically, disruption of EGFR signaling generated a cell-intrinsic hypersensitivity within the JAK-STAT1 pathway, which, synergistically with interferon gamma expressing CD8 T-cell and NK-cell-mediated inflammation, compromised the stem cell niche. Hair follicle-specific genetic depletion of either JAK1/2 or STAT1 or therapeutic inhibition of JAK1/2 ameliorated the inflammation, restored skin barrier function and activated the residual stem cells to resume hair growth in mouse models of epidermal and hair follicle-specific EGFR deletion. Skin biopsies from EGFR inhibitor-treated and cicatricial alopecia patients revealed an active JAK-STAT1 signaling signature along with upregulation of antigen presentation and downregulation of key components of the EGFR pathway. Our findings offer molecular insights and highlight a mechanism-based therapeutic strategy for addressing chronic folliculitis associated with EGFR-inhibitor anti-cancer therapy and cicatricial alopecia.

Epidermal growth factor receptor/mitogen-activated kinase inhibitor treatment induces a distinct inflammatory hair follicle response that includes collapse of immune privilege

BACKGROUND

Inhibitors of epidermal growth factor receptor (EGFRi) or mitogen-activated kinase (MEKi) induce a folliculitis in 75-90% of patients, the pathobiology of which remains insufficiently understood.

OBJECTIVES

To characterize changes in the skin immune status and global transcriptional profile of patients treated with EGFRi; to investigate whether EGFRi affects the hair follicle's (HF) immune privilege (IP); and to identify early proinflammatory signals induced by EGFRi/MEKi in human scalp HFs ex vivo.

METHODS

Scalp biopsies were taken from patients exhibiting folliculitis treated long term with EGFRi ('chronic EGFRi' group, n = 9) vs. healthy scalp skin (n = 9) and patients prior to commencing EGFRi treatment and after 2 weeks of EGFRi therapy ('acute EGFRi' group, n = 5). Healthy organ-cultured scalp HFs were exposed to an EGFRi (erlotinib, n = 5) or a MEKi (cobimetinib, n = 5). Samples were assessed by quantitative immunohistomorphometry, RNA sequencing (RNAseq) and in situ hybridization.

RESULTS

The 'chronic EGFRi' group showed CD8+ T-cell infiltration of the bulge alongside a partial collapse of the HF's IP, evidenced by upregulated major histocompatibility complex (MHC) class I, β2-microglobulin (B2 M) and MHC class II, and decreased transforming growth factor-β1 protein expression. Healthy HFs treated with EGFRi/MEKi ex vivo also showed partial HF IP collapse and increased transcription of human leucocyte antigen (HLA)-A, HLA-DR and B2 M transcripts. RNAseq analysis showed increased transcription of chemokines (CXCL1, CXCL13, CCL18, CCL3, CCL7) and interleukin (IL)-26 in biopsies from the 'chronic EGFRi' cohort, as well as increased IL-33 and decreased IL-37 expression in HF biopsies from the 'acute EGFRi' group and in organ-cultured HFs.

CONCLUSIONS

The data show that EGFRi/MEKi compromise the physiological IP of human scalp HFs and suggest that future clinical management of EGFRi/MEKi-induced folliculitis requires HF IP protection and inhibition of IL-33.

Cancer Therapy-induced Dermatotoxicity as a Window to Understanding Skin Immunity

Pruritus, rash, and various other forms of dermatotoxicity are the most frequent adverse events among patients with cancer receiving targeted molecular therapy and immunotherapy. Immune checkpoint inhibitors, macrophage-targeting agents, and epidermal growth factor receptor/MEK inhibitors not only exert antitumor effects but also interfere with molecular pathways essential for skin immune homeostasis. Studying cancer therapy-induced dermatotoxicity helps us identify molecular mechanisms governing skin immunity and deepen our understanding of human biology. This review summarizes new mechanistic insights emerging from the analysis of cutaneous adverse events and discusses knowledge gaps that remain to be closed by future research.

Inflammatory Mediators Suppress FGFR2 Expression in Human Keratinocytes to Promote Inflammation

Fibroblast growth factors (FGFs) are key orchestrators of development, tissue homeostasis and repair. FGF receptor (FGFR) deficiency in mouse keratinocytes causes an inflammatory skin phenotype with similarities to atopic dermatitis, but the human relevance is unclear. Therefore, we generated human keratinocytes with a CRISPR/Cas9-induced knockout of FGFR2. Loss of this receptor promoted the expression of interferon-stimulated genes and pro-inflammatory cytokines under homeostatic conditions and in particular in response to different inflammatory mediators. Expression of FGFR2 itself was strongly downregulated in cultured human keratinocytes exposed to various pro-inflammatory stimuli. This is relevant in vivo, because bioinformatics analysis of bulk and single-cell RNA-seq data showed strongly reduced expression of FGFR2 in lesional skin of atopic dermatitis patients, which likely aggravates the inflammatory phenotype. These results reveal a key function of FGFR2 in human keratinocytes in the suppression of inflammation and suggest a role of FGFR2 downregulation in the pathogenesis of atopic dermatitis and possibly other inflammatory diseases.

New-onset keratitis associated with epidermal growth factor receptor-based targeted therapies in Han Chinese patients with lung cancer: A multi-center cohort study

PURPOSE

To determine the risk and incidence of keratitis following treatment with epidermal growth factor receptor inhibitors (EGFRi) and subtypes of EGFRi-associated keratitis.

METHODS

This multi-center cohort study included EGFRi-treated patients and non-users with lung cancer between 2010 and 2023. EGFRi included first-generation agent gefitinib and erlotinib, second-generation agent afatinib, and third-generation agent osimertinib. The primary outcome was new-onset keratitis. Cox proportional hazard models with multivariable adjustment were applied to determine the effect of EGFRi on keratitis over time. Subgroup analyses were conducted, stratified by agents of EGFRi. Sub-outcome analyses were performed to identify the subtypes of EGFRi-associated keratitis.

RESULTS

A total of 1549 EGFRi-treated patients and 6146 non-users were included. 38 (2.5%) EGFRi-treated patients developed keratitis. The incidence of keratitis in EGFRi-treated patients was significantly higher than that in controls (incidence rate, IR, per 1000 person-years = 14.7 vs 4.49, p < 0.0001). EGFRi-treated patients presented with an increased risk for keratitis (adjusted hazard ratio, aHR = 3.14, 95% CI = 1.85-5.35, p < 0.001). Erlotinib (aHR = 2.64, 95% CI = 1.35-5.15, p = 0.004), afatinib (aHR = 4.42, 95% CI = 2.17-9.02, p < 0.001), and osimertinib (aHR = 4.67, 95% CI = 1.60-13.64, p = 0.005), but not gefitinib (aHR = 2.30, 95% CI = 0.96-5.55, p = 0.063), significantly contributed to the risk of keratitis. Subtypes of EGFRi-associated keratitis included corneal ulcer (IR = 2.31 vs 0.166, p < 0.0001) and keratoconjunctivitis (IR = 9.27 vs 2.91, p < 0.0001). None of the EGFRi-treated patients developed perforated corneal ulcer, interstitial and deep keratitis, or corneal neovascularization.

CONCLUSION

Treatment with EGFRi was associated with an increased risk of keratitis. Ocular toxicity of EGFRi was highest for third-generation agents, followed by second-generation agents, and then first-generation agents.

Topical JAK inhibition ameliorates EGFR inhibitor-induced rash in rodents and humans

Epidermal growth factor receptor inhibitors (EGFRis) are used to treat many cancers, but their use is complicated by the development of a skin rash that may be severe, limiting their use and adversely affecting patient quality of life. Most studies of EGFRi-induced rash have focused on the fully developed stage of this skin disorder, and early pathological changes remain unclear. We analyzed high-throughput transcriptome sequencing of skin samples from rats exposed to the EGFRi afatinib and identified that keratinocyte activation is an early pathological alteration in EGFRi-induced rash. Mechanistically, the induction of S100 calcium-binding protein A9 (S100A9) occurred before skin barrier disruption and led to keratinocyte activation, resulting in expression of specific cytokines, chemokines, and surface molecules such as interleukin 6 (Il6) and C-C motif chemokine ligand 2 (CCL2) to recruit and activate monocytes through activation of the Janus kinase (JAK)-signal transducers and activators of transcription (STAT) pathway, further recruiting more immune cells. Topical JAK inhibition suppressed the recruitment of immune cells and ameliorated the severity of skin rash in afatinib-treated rats and mice with epidermal deletion of EGFR, while having no effect on EGFRi efficacy in tumor-bearing mice. In a pilot clinical trial (NCT05120362), 11 patients with EGFRi-induced rash were treated with delgocitinib ointment, resulting in improvement in rash severity by at least one grade in 10 of them according to the MASCC EGFR inhibitor skin toxicity tool (MESTT) criteria. These findings provide a better understanding of the early pathophysiology of EGFRi-induced rash and suggest a strategy to manage this condition.

Amputation Triggered by Gefitinib: An Unusual Clinical Presentation

Gefitinib is an epidermal growth factor tyrosine kinase inhibitor used as a targeted chemotherapeutic agent in the treatment of lung cancer and other solid malignancies. The most common adverse effects of gefitinib include dermatological side effects and gastrointestinal symptoms, with rare reports of vascular side effects such as myocardial infarction and stroke. We recently reported a case of a patient with diabetes and multiple comorbidities who developed a serious lower limb vascular adverse event after gefitinib treatment, ultimately leading to amputation surgery. This is the first reported case of lower extremity amputation following gefitinib therapy in a patient with type 2 diabetes mellitus and lung adenocarcinoma. This case highlights the potential risk of amputation in diabetic patients receiving targeted therapies like gefitinib, especially in those with vascular complications. It emphasizes the importance of exercising extra caution when dealing with these patients.

Comparative immunohistochemical analysis suggests a conserved role of EPS8L1 in epidermal and hair follicle barriers of mammals

The mammalian skin and its appendages depend on tightly coordinated differentiation of epithelial cells. Epidermal growth factor receptor (EGFR) pathway substrate 8 (EPS8) like 1 (EPS8L1) is enriched in the epidermis among human tissues and has also been detected in the epidermis of lizards. Here, we show by the analysis of single-cell RNA-sequencing data that EPS8L1 mRNA is co-expressed with filaggrin and loricrin in terminally differentiated human epidermal keratinocytes. Comparative genomics indicated that EPS8L1 is conserved in all main clades of mammals, whereas the orthologous gene has been lost in birds. Using a polyclonal antibody against EPS8L1, we performed an immunohistochemical screening of skin from diverse mammalian species and immuno-electron microscopy of human skin. EPS8L1 was detected predominantly in the granular layer of the epidermis in monotremes, marsupial, and placental mammals. The labeling was partly associated with cell membranes, and it was evident along the perimeter of keratinocytes at the transition with the cornified layer of the epidermis, similar to involucrin distribution. Basal, spinous, and the fully mature cornified layers lacked immunolabeling of EPS8L1. In addition to the epidermis, the hair follicle inner root sheath (IRS) was immunolabeled. Both epidermal granular layer and IRS contribute to the barrier function of the skin, suggesting that EPS8L1 is involved in the regulation of these barriers.

Single-Cell RNA-Seq Reveals Coronary Heterogeneity and Identifies CD133+TRPV4high Endothelial Subpopulation in Regulating Flow-Induced Vascular Tone in Mice

BACKGROUND

Single-cell RNA-Seq analysis can determine the heterogeneity of cells between different tissues at a single-cell level. Coronary artery endothelial cells (ECs) are important to coronary blood flow. However, little is known about the heterogeneity of coronary artery ECs, and cellular identity responses to flow. Identifying endothelial subpopulations will contribute to the precise localization of vascular endothelial subpopulations, thus enabling the precision of vascular injury treatment.

METHODS

Here, we performed a single-cell RNA sequencing of 31 962 cells and functional assays of 3 branches of the coronary arteries (right coronary artery/circumflex left coronary artery/anterior descending left coronary artery) in wild-type mice.

RESULTS

We found a compendium of 7 distinct cell types in mouse coronary arteries, mainly ECs, granulocytes, cardiac myocytes, smooth muscle cells, lymphocytes, myeloid cells, and fibroblast cells, and showed spatial heterogeneity between arterial branches. Furthermore, we revealed a subpopulation of coronary artery ECs, CD133+TRPV4high ECs. TRPV4 (transient receptor potential vanilloid 4) in CD133+TRPV4high ECs is important for regulating vasodilation and coronary blood flow.

CONCLUSIONS

Our study elucidates the nature and range of coronary arterial cell diversity and highlights the importance of coronary CD133+TRPV4high ECs in regulating coronary vascular tone.

Traditional Chinese Medicine Formulae QY305 Reducing Cutaneous Adverse Reaction and Diarrhea by its Nanostructure

Traditional Chinese medicine (TCM) is widely used in clinical practice, including skin and gastrointestinal diseases. Here, a potential TCM QY305 (T-QY305) is reported that can modulate the recruitment of neutrophil in skin and colon tissue thus reducing cutaneous adverse reaction and diarrhea induced by epidermal growth factor receptor inhibitors (EGFRIs). On another hand, the T-QY305 formula, through regulating neutrophil recruitment features would highlight the presence of N-QY305, a subunit nanostructure contained in T-QY305, and confirm its role as potentially being the biomaterial conferring to T-QY305 its pharmacodynamic features. Here, the clinical records of two patients are analyzed expressing cutaneous adverse reaction and demonstrate positive effect of T-QY305 on the simultaneous inhibition of both cutaneous adverse reaction and diarrhea in animal models. The satisfying results obtained from T-QY305, lead to further process to the isolation of N-QY305 from T-QY305, in order to demonstrate that the potency of T-QY305 originates from the nanostructure N-QY305. Compared to T-QY305, N-QY305 exhibits higher potency upon reducing adverse reactions. The data represent a promising candidate for reducing cutaneous adverse reaction and diarrhea, meanwhile proposing a new strategy to highlight the presence of nanostructures being the "King" of Chinese medicine formula as the pharmacodynamic basis.

Emerging Role of the IL-36/IL-36R Axis in Multiple Inflammatory Skin Diseases

IL-36 is a most recent member of the IL-1 cytokine family, primarily expressed at barrier sites of the body such as the skin, lungs, and intestine. It plays a vital role in inflammation and is implicated in the development of various cutaneous; intestinal; and pulmonary disorders, including psoriasis, inflammatory bowel disease, and chronic obstructive pulmonary disease. IL-36 comprises 4 isoforms: the proinflammatory IL-36α, IL-36β, and IL-36γ and the anti-inflammatory IL-36R antagonist. An imbalance between proinflammatory and anti-inflammatory IL-36 isoforms can contribute to the inflammatory fate of cells and tissues. IL-36 cytokines signal through an IL-36R heterodimer mediating their function through canonical signaling cacade, including the NF-B pathway. Prominent for its role in psoriasis, IL-36 has recently been associated with disease mechanisms in atopic dermatitis, hidradenitis suppurativa, neutrophilic dermatoses, autoimmune blistering disease, and Netherton syndrome. The major cutaneous source of IL-36 cytokines is keratinocytes, pointing to its role in the communication between the epidermis, innate (neutrophils, dendritic cells) immune system, and adaptive (T helper [Th]1 cells, Th17) immune system. Thus, cutaneous IL-36 signaling is crucial for the immunopathological outcome of various skin diseases. Consequently, the IL-36/IL-36R axis has recently been recognized as a promising drug target for the treatment of inflammatory disorders beyond psoriasis. This review summarizes the current update on IL-36 cytokines in inflammatory skin diseases.

Facial Papulopustular Eruption during the COVID-19 Pandemic in Patients Treated with EGFR Inhibitors

Papulopustular rash (PPR) is the most frequent cutaneous adverse event during treatment with epidermal growth factor receptor inhibitors (EGFRis). Although often mild in severity, it can impair patients' quality of life and may also be a reason for discontinuing or changing the dose of the antineoplastic treatment. During COVID-19 pandemics, the use of surgical masks drastically increased and it had an impact on the face skin microenvironment, favoring the worsening of dermatological pathologies. We reported the relapse of PPR in patients treated with EGFR inhibitors who consistently wore face masks (>6 hours/day). All the patients developed the PPR within 6 months of starting mask use. Compared to the PPR occurred previously, after mask use, the skin eruption was more severe and affected mainly those regions of the face which came into contact with the mask. Patients received topical or systemic treatment, obtaining complete response in 65.7% of the cases. The establishment of an early treatment for the PPR allows continuing the oncologic treatment, without any suspension which could result in a decreased oncologic outcome. In conclusion, when using these devices, it is recommended to use special precautions, particularly in oncologic patients, by using a daily prophylactic skincare and replacing masks regularly with regular and frequent breaks.

Staphylococcus aureus β-hemolysin causes skin inflammation by acting as an agonist of epidermal growth factor receptor

IMPORTANCE

Staphylococcus aureus is a Gram-positive opportunistic bacterium that is responsible for the majority of skin infections in humans. Our study provides important molecular insights into the pathogenesis of S. aureus skin infections and identifies a potential therapeutic target for the treatment of these infections. Our findings also indicate that β-hemolysin (Hlb) secreted by colonized S. aureus is a risk factor for epidermal growth factor receptor (EGFR)-related diseases by acting as an agonist of EGFR. The neutralized monoclonal antibody we have developed for the first time will provide a functional inhibitor of Hlb. This study provides important insights to better understand the relationship between the skin colonization of S. aureus and inflammatory skin diseases.

Adverse Effects of Gefitinib on Skin and Colon in a Lung Cancer Mouse Model

BACKGROUND

Gefitinib, an Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR-TKI), frequently causes side effects when used to treat non-small cell lung cancer.

OBJECTIVE

The purpose of this experiment was to investigate the side effect of gefitinib on the skin and colon of mice.

METHODS

Male Balb/c nu-nu nude mice aged 4-5 weeks were used as xenograft tumor models, and gefitinib at 150 mg/kg and 225 mg/kg was started at 9 days after the xenograft tumor grew out. The mice's weights and tumor volumes were tracked concurrently, and the mouse skin adverse reactions and diarrhea were observed during the treatment. The animal tissues were subjected to biochemical and pathological evaluations after 14 days.

RESULTS

Gefitinib effectively decreased the size and weight of transplanted tumors in nude mice, while also lowering body weight and raising indexes of the liver and spleen. Gefitinib could cause skin adverse reactions and diarrhea in mice. Further pathological investigation revealed tight junction- related markers in the mice's skin and colon to be reduced and macrophages and neutrophils to be increased after gefitinib treatment.

CONCLUSION

The findings imply that gefitinib has negative effects on the skin and colon. Gefitinib- induced skin and colon adverse reactions in mice have been successfully modeled in this study.

Menahydroquinone-4 may play a key role in regulating CCL5 expression induced by epidermal growth factor receptor inhibitors

Epidermal growth factor receptor (EGFR) inhibitors frequently cause severe skin rash as a side effect, which is a critical burden for patients who continuously receive drug treatments. Several recent clinical trials have shown that vitamin K is effective against these side effects; however, the underlying mechanisms remain unclear. EGFR inhibitors induce C-C motif chemokine ligand 5 (CCL5) in dermopathy. We hypothesized that menahydroquinone-4 (MKH), the active form of menaquinone-4 (MK-4, vitamin K2(20)), supplied by biosynthesis or external delivery, is essential for the suppressive effect on CCL5. The aim of this study was to explore the underlying mechanisms governing the relieving effects of MKH against skin rashes caused by EGFR inhibitors. The responses generated by EGFR inhibitors and the effect of MKH derivatives (two ester derivatives and MK-4) on them were evaluated using human skin cell lines (HaCaT and HSC-1). EGFR inhibitors downregulated UbiA prenyltransferase domain-containing protein-1 (UBIAD1, MKH synthetase) expression and MKH biosynthesis. Knockdown of UBIAD1 or γ-glutamyl carboxylase and treatment with warfarin upregulated CCL5 expression. MKH derivatives suppressed the CCL5 expression induced by EGFR inhibitors. Our data strongly suggest that MKH is involved in suppressing CCL5 expression and alleviating the skin damage caused by EGFR inhibitors.

Mapping the landscape of artificial intelligence in skin cancer research: a bibliometric analysis

Objective

Artificial intelligence (AI), with its potential to diagnose skin cancer, has the potential to revolutionize future medical and dermatological practices. However, the current knowledge regarding the utilization of AI in skin cancer diagnosis remains somewhat limited, necessitating further research. This study employs visual bibliometric analysis to consolidate and present insights into the evolution and deployment of AI in the context of skin cancer. Through this analysis, we aim to shed light on the research developments, focal areas of interest, and emerging trends within AI and its application to skin cancer diagnosis.

Methods

On July 14, 2023, articles and reviews about the application of AI in skin cancer, spanning the years from 1900 to 2023, were selected from the Web of Science Core Collection. Co-authorship, co-citation, and co-occurrence analyses of countries, institutions, authors, references, and keywords within this field were conducted using a combination of tools, including CiteSpace V (version 6.2. R3), VOSviewer (version 1.6.18), SCImago, Microsoft Excel 2019, and R 4.2.3.

Results

A total of 512 papers matching the search terms and inclusion/exclusion criteria were published between 1991 and 2023. The United States leads in publications with 149, followed by India with 61. Germany holds eight positions among the top 10 institutions, while the United States has two. The most prevalent journals cited were Cancer, the European Journal of Cancer, and Sensors. The most frequently cited keywords include "skin cancer", "classification", "artificial intelligence", and "deep learning".

Conclusions

Research into the application of AI in skin cancer is rapidly expanding, and an increasing number of scholars are dedicating their efforts to this field. With the advancement of AI technology, new opportunities have arisen to enhance the accuracy of skin imaging diagnosis, treatment based on big data, and prognosis prediction. However, at present, the majority of AI research in the field of skin cancer diagnosis is still in the feasibility study stage. It has not yet made significant progress toward practical implementation in clinical settings. To make substantial strides in this field, there is a need to enhance collaboration between countries and institutions. Despite the potential benefits of AI in skin cancer research, numerous challenges remain to be addressed, including developing robust algorithms, resolving data quality issues, and enhancing results interpretability. Consequently, sustained efforts are essential to surmount these obstacles and facilitate the practical application of AI in skin cancer research.

FAM3C/ILEI protein is elevated in psoriatic lesions and triggers psoriasiform hyperproliferation in mice

FAM3C/ILEI is an important cytokine for tumor progression and metastasis. However, its involvement in inflammation remains elusive. Here, we show that ILEI protein is highly expressed in psoriatic lesions. Inducible keratinocyte-specific ILEI overexpression in mice (K5-ILEIind ) recapitulates many aspects of psoriasis following TPA challenge, primarily manifested by impaired epidermal differentiation and increased neutrophil recruitment. Mechanistically, ILEI triggers Erk and Akt signaling, which then activates STAT3 via Ser727 phosphorylation. Keratinocyte-specific ILEI deletion ameliorates TPA-induced skin inflammation. A transcriptomic ILEI signature obtained from the K5-ILEIind model shows enrichment in several signaling pathways also found in psoriasis and identifies urokinase as a targetable enzyme to counteract ILEI activity. Pharmacological inhibition of urokinase in TPA-induced K5-ILEIind mice results in significant improvement of psoriasiform symptoms by reducing ILEI secretion. The ILEI signature distinguishes psoriasis from healthy skin with uPA ranking among the top "separator" genes. Our study identifies ILEI as a key driver in psoriasis, indicates the relevance of ILEI-regulated genes for disease manifestation, and shows the clinical impact of ILEI and urokinase as novel potential therapeutic targets in psoriasis.

Ocular surface complications following biological therapy for cancer

Novel and highly effective biological agents developed to treat cancer over the past two decades have also been linked to multiple adverse outcomes, including unanticipated consequences for the cornea. This review provides an overview of adverse corneal complications of biological agents currently in use for the treatment of cancer. Epidermal growth factor receptor inhibitors and immune checkpoint inhibitors are the two classes of biological agents most frequently associated with corneal adverse events. Dry eye, Stevens-Johnson syndrome, and corneal transplant rejection have all been reported following the use of immune checkpoint inhibitors. The management of these adverse events requires close collaboration between ophthalmologists, dermatologists, and oncologists. This review focuses in depth on the epidemiology, pathophysiology, and management of ocular surface complications of biological therapies against cancer.

Preventing skin toxicities induced by EGFR inhibitors by topically blocking drug-receptor interactions

Epidermal growth factor receptor (EGFR) inhibitors are used to treat many advanced-stage epithelial cancers but induce severe skin toxicities in most treated patients. These side effects lead to a deterioration in the quality of life of the patients and compromise the anticancer treatment. Current treatment strategies for these skin toxicities focus on symptom reduction rather than preventing the initial trigger that causes the toxicity. In this study, we developed a compound and method for treating "on-target" skin toxicity by blocking the drug at the site of toxicity without reducing the systemic dose reaching the tumor. We first screened for small molecules that effectively blocked the binding of anti-EGFR monoclonal antibodies to EGFR and identified a potential candidate, SDT-011. In silico docking predicted that SDT-011 interacted with the same residues on EGFR found to be important for the binding of EGFR inhibitors cetuximab and panitumumab. Binding of SDT-011 to EGFR reduced the binding affinity of cetuximab to EGFR and could reactivate EGFR signaling in keratinocyte cell lines, ex vivo cetuximab-treated whole human skin, and A431-injected mice. Specific small molecules were topically applied and were delivered via a slow-release system derived from biodegradable nanoparticles that penetrate the hair follicles and sebaceous glands, within which EGFR is highly expressed. Our approach has the potential to reduce skin toxicity caused by EGFR inhibitors.

Xijiao Dihuang decoction relieves the erlotinib-induced dermatitis

BACKGROUND

Erlotinib treatment can lead to skin diseases that drastically affected the quality of life of patients. Quercetin (Que), the active component in Xijiao Dihuang Decoction (XDD), was identified to improve inflammatory skin diseases. However, the mechanism of XDD treating erlotinib-induced cutaneous toxicity was not clear at the molecular level.

METHODS

Keratinocytes were treated with erlotinib, and the expression of inflammatory cytokines and chemokines was revealed by ELISA and qRT-PCR. The macrophage polarization was determined by flow cytometry. The key component of XDD, Que, and the target genes of dermatitis were selected via network pharmacology analysis. The binding effects of Que and target genes were verified using molecular docking and cellular thermal shift assay (CETSA)-western blot assay. Animal experiments were performed in vivo to verify the therapeutic effect of XDD on erlotinib-induced skin toxicity.

RESULTS

Erlotinib induced M1 polarization of macrophages after stimulating epidermal keratinocytes. While this effect was associated with increased production of inflammatory cytokines and chemokines, such production was prominently decreased by XDD treatment. By combining network pharmacological analysis, molecular docking, and CETSA, it was confirmed that Que had a binding relationship with IL-2 and CXCL8. In vivo results implied that erlotinib abated tumor growth and stimulated dermatitis in HR-1 nude mice, while Que alleviated erlotinib-induced skin damage without affecting this tumor repression effect.

CONCLUSION

The results indicated that XDD could relieve the dermatitis induced by erlotinib and provide a favorable theoretical basis for the clinical relief by using this method.

Comparison of Plasma Metabolites From Patients With Non-Small Cell Lung Cancer by Erlotinib Treatment and Skin Rash

Erlotinib is a necessary anticancer treatment for non-small cell lung cancer (NSCLC) patients yet it causes severe side effects such as skin rash. In this study, researchers compared the untargeted compound profiles before and after erlotinib administration to observe changes in blood metabolites in NSCLC patients. The levels of 1005 substances changed after taking erlotinib. The levels of 306 and 699 metabolites were found to have increased and decreased, respectively. We found 5539 substances with peak area differences based on the presence of skin rash. Carbohydrate, amino acid, and vitamin metabolic pathways were altered in response to the onset of erlotinib-induced skin rash. Finally, this study proposed using plasma metabolites to identify biomarker(s) induced by erlotinib, as well as target molecule(s), for the treatment of dermatological toxic effects.

Persistent alteration of the skin microbiome in patients with skin rash after receiving EGFR inhibitor treatment

The pathological mechanism responsible for EGFR inhibitor (EGFRI)-induced skin rash remains unclear. Recent studies reveal associations between skin dysbiosis and skin inflammatory diseases. This study aimed to examine whether skin dysbiosis is associated with EGFRI-induced skin rash. Bacterial swabs were taken from the forehead of 17 cancer patients at baseline and at several time points after EGFRIs initiation, as well as from 20 healthy controls. The skin microbiome was analysed using 16S rRNA sequencing. The severity of the skin rash was assessed using the rash grade. Skin surface parameters (pH, water capacitance, and sebum level) were also measured. Compared with baseline, the abundance of Cutibacterium acnes decreased in 13 of 15 cases, and that of Staphylococcus aureus, Corynebacterium spp., Staphylococcus epidermidis or Proteobacteria increased in 13 of 15 cases after EGFRIs initiation. Skin pH increased significantly in parallel with a decrease in water capacitance after EGFRI initiation. Also, the composition of the skin microbiome of patients with severe rash was significantly different from that of healthy controls. In addition, the skin dysbiosis did not return to baseline during EGFRIs treatment for >1 year. These longitudinal observations indicate that skin dysbiosis is associated with development of skin rash.

Therapeutic targets and signaling mechanisms of dasatinib activity against radiation skin ulcer

Objective

To reveal the potential targets and signaling pathways of dasatinib in the treatment of radiation ulcers through network pharmacology and molecular docking technology.

Methods

Pathological targets of radiation ulcers were screened using GeneCards database. At the same time, the pharmacological targets of dasatinib were obtained through SwissTargetPrediction (STP), Binding DB and Drugbank databases. Subsequently, the potential targets of dasatinib for anti-radiation ulcers were obtained after intersection by Venn diagram. Next, a protein-protein interaction (PPI) network was constructed through the STRING database and core targets were screened. Finally, the identified core targets were subjected to GO and KEGG enrichment analysis, co-expression network analysis, and molecular docking technology to verify the reliability of the core targets.

Results

A total of 76 potential targets for anti-radiation ulcer with dasatinib were obtained, and 6 core targets were screened, including EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These genes were mainly enriched in Adherens junction, EGFR tyrosine kinase inhibitor resistance, Focal adhesion, Bladder cancer and PI3K-Akt signaling pathway. Molecular docking results showed that dasatinib binds well to the core target.

Conclusion

Dasatinib may play a role in the treatment of radiation ulcers by regulating EGFR, ERBB2, FYN, JAK2, KIT, and SRC. These core targets may provide new insights for follow-up studies of radiation ulcers.

Identification of Molecular Determinants in iRhoms1 and 2 That Contribute to the Substrate Selectivity of Stimulated ADAM17

The metalloprotease ADAM17 is a key regulator of the TNFα, IL-6R and EGFR signaling pathways. The maturation and function of ADAM17 is controlled by the seven-membrane-spanning proteins iRhoms1 and 2. The functional properties of the ADAM17/iRhom1 and ADAM17/iRhom2 complexes differ, in that stimulated shedding of most ADAM17 substrates tested to date can be supported by iRhom2, whereas iRhom1 can only support stimulated shedding of very few ADAM17 substrates, such as TGFα. The first transmembrane domain (TMD1) of iRhom2 and the sole TMD of ADAM17 are important for the stimulated shedding of ADAM17 substrates by iRhom2. However, little is currently known about how the iRhoms interact with different substrates to control their stimulated shedding by ADAM17. To provide new insights into this topic, we tested how various chimeras between iRhom1 and iRhom2 affect the stimulated processing of the EGFR-ligands TGFα (iRhom1- or 2-dependent) and EREG (iRhom2-selective) by ADAM17. This uncovered an important role for the TMD7 of the iRhoms in determining their substrate selectivity. Computational methods utilized to characterize the iRhom1/2/substrate interactions suggest that the substrate selectivity is determined, at least in part, by a distinct accessibility of the substrate cleavage site to stimulated ADAM17. These studies not only provide new insights into why the substrate selectivity of stimulated iRhom2/ADAM17 differs from that of iRhom1/ADAM17, but also suggest new approaches for targeting the release of specific ADAM17 substrates.

Tideglusib promotes wound healing in aged skin by activating PI3K/Akt pathway

Background

Aging disturbs the skin morphology and function, manifested as thinned epithelium and impaired wound healing. As a major type of skin cells, epidermal stem cells (EpiSCs) are inevitably affected by aging. The effect of age on EpiSCs and wound healing needs to be further explored.

Methods

Skin RNA-seq data of young (5 months) and old (30 months) CB6F1 mice were obtained from GEO Series GSE35322 with 10 in each age group. Differentially expressed genes were analyzed, and EpiSCs-related pathways were enriched by KEGG. The age-related changes of the screened PI3K/Akt pathway were validated by Western Blot and immunofluorescence of epidermis of SD rats (2, 17, and 23 months, n = 6). The expression of upstream protein EGFR was assessed by immunofluorescence in skin of mice (4, 13, and 23 months, n = 6) and human (respectively, 23, 28, 30 years old in the young group and 69, 73, 78 years old in the old group) skin. Inhibitors of EGFR were used to verify its effects on EpiSCs and wound healing. The small molecule drug Tideglusib was tested for its effects on signaling pathways of EpiSCs and wound healing of aged rats. Western Blot was used for the detection of signaling pathways in in vitro experiments. Cell migration assays were used to assess cell migration ability. Flow cytometry was used to detect changes in cell cycle and apoptosis levels. Sulforhodamine B assay and CCK-8 assay were used to evaluate cell proliferation and viability, respectively. Student’s t test and one-way analysis of variance (ANOVA) followed by the multiple comparisons Bonferroni test were used for statistical analysis. The 0.05 level of confidence was accepted as a significant difference.

Results

EpiSCs-related PI3K/Akt pathway was enriched by KEGG and verified by decreased phosphorylation of Akt (32.1 ± 13.8%, P < 0.01) and mTOR (38.9 ± 11.8%, P < 0.01) in aged epidermis of rats. Furthermore, the expression of PI3K/Akt-upstream EGFR decreased with age in the epidermis of mouse (27.6 ± 5.5%, P < 0.01) and human (25.8 ± 9.3%, P < 0.01). With EGFR blocked by Erlotinib, EpiSCs showed reduced phosphorylation of Akt (30.4 ± 10.6%, P < 0.01) and mTOR (39.8 ± 12.8%, P < 0.01), impaired proliferation and migration after incubated for 24 h and 36 h (P < 0.05), and higher levels of apoptosis (11.9 ± 1.7%, P < 0.05), and rats showed slower wound healing from d7 to d14 after wounding (P < 0.01). In addition to slower wound healing rates, aged rats also showed a decrease in the efficacy of EGF, partly due to the downregulated EGFR expression. By activating PI3K/Akt pathway, Tideglusib promoted the proliferation and migration of EpiSCs with apoptosis inhibited (P < 0.01) and accelerated wound healing in aged rats from d7 to d14 after wounding (P < 0.05). Notably, the combined use of Tideglusib and EGF could further enhance wound healing in aged rats.

Conclusions

The decreased expression of EGFR in epidermis with age resulted in decreased activity of the PI3K/Akt pathway and limited EGF efficacy. Tideglusib could assist wound healing in aged rats via activating PI3K/Akt pathway, which may be considered as an ingredient for medical and cosmetics use.

GPCR-mediated EGFR transactivation ameliorates skin toxicities induced by afatinib

Many G-protein-coupled receptor (GPCR) agonists have been studied for transactivating epidermal growth factor receptor (EGFR) signaling through extracellular or intracellular pathways. Accumulated evidence has confirmed that GPCR transactivation participates in various diseases. However, the clinical application of GPCR transactivation has not been explored, and more translational studies are needed to develop therapies to target GPCR-mediated EGFR transactivation. In cancer patients treated with EGFR inhibitors (EGFRi), especially afatinib, a unique acneiform rash is frequently developed. In this study, we first established the connection between GPCR transactivation and EGFRi-induced skin disease. We examined the ability of three different GPCR agonists to reverse signaling inhibition and ameliorate rash induced by EGFRi. The activation of different agonists follows unique time and kinase patterns. Rats treated with EGFRi show a similar skin phenotype, with rash occurring in the clinic; correspondingly, treatment with GPCR agonists reduced keratinocyte apoptosis, growth retardation and infiltration of inflammatory cytokines by transactivation. This phenomenon demonstrates that EGFR inhibition in keratinocytes regulates key factors associated with rash. Our findings indicate that maintaining EGFR signaling by GPCR agonists might provide a possible therapy for EGFR inhibitor-induced skin toxicities. Our study provides the first example of the translational application of GPCR transactivation in treating diseases.

The Desmosome-Keratin Scaffold Integrates ErbB Family and Mechanical Signaling to Polarize Epidermal Structure and Function

While classic cadherin-actin connections in adherens junctions (AJs) have ancient origins, intermediate filament (IF) linkages with desmosomal cadherins arose in vertebrate organisms. In this mini-review, we discuss how overlaying the IF-desmosome network onto the existing cadherin-actin network provided new opportunities to coordinate tissue mechanics with the positioning and function of chemical signaling mediators in the ErbB family of receptor tyrosine kinases. We focus in particular on the complex multi-layered outer covering of the skin, the epidermis, which serves essential barrier and stress sensing/responding functions in terrestrial vertebrates. We will review emerging data showing that desmosome-IF connections, AJ-actin interactions, ErbB family members, and membrane tension are all polarized across the multiple layers of the regenerating epidermis. Importantly, their integration generates differentiation-specific roles in each layer of the epidermis that dictate the form and function of the tissue. In the basal layer, the onset of the differentiation-specific desmosomal cadherin desmoglein 1 (Dsg1) dials down EGFR signaling while working with classic cadherins to remodel cortical actin cytoskeleton and decrease membrane tension to promote cell delamination. In the upper layers, Dsg1 and E-cadherin cooperate to maintain high tension and tune EGFR and ErbB2 activity to create the essential tight junction barrier. Our final outlook discusses the emerging appreciation that the desmosome-IF scaffold not only creates the architecture required for skin's physical barrier but also creates an immune barrier that keeps inflammation in check.

PROPHYLACTIC EFFECT OF NITRIC OXIDE DONORS ON RAT MODELS OF EGFR INHIBITORS-INDUCED CUTANEOUS TOXICITIES

Epidermal growth factor receptor inhibitors (EGFRIs) have been established as first-line standard-of-care therapies for non-small cell lung cancer (NSCLC) but are frequently accompanied by adverse dermatological effects, in particular, acneiform rash. There is no effective clinical intervention, partially because of its poorly understood etiology. Here, we show that inhibition of EGFR initiated keratinocyte HaCaT cell cycle arrest and apoptosis, which fueled a robust secondary inflammatory response. Rats gavaged with EGFRI showed a phenotype similar to that of clinical patients, which was in line with the interrupted functions observed in HaCaT keratinocytes. We found that a nitric oxide (NO) donor, nitroglycerin (GTN), was a feasible treatment alternative for EGFRI-induced rash. Restoration of epidermal extracellular signal-regulated kinase (ERK) and a reduction in STAT3 signaling via GTN treatment rescued the cellular functions that had been damaged in vitro and further ameliorated the rash in rat models. In addition, the efficacy of GTN was superior to that of existing clinical interventions. These data highlighted the importance of epidermal EGFR signaling and led to the identification of a small-molecule NO donor as a mediator that can maintain EGFR pathway functions during anti-EGFR therapies, providing a therapeutic anchor point for adverse EGFRI-induced skin effects.

Decreased HMGB1 expression contributed to cutaneous toxicity caused by lapatinib

The application of lapatinib, a widely used dual inhibitor of human epidermal growth factor receptor 1 (EGFR/ERBB1) and 2 (HER2/ERBB2), has been seriously limited due to cutaneous toxicity. However, the specific mechanism of lapatinib-induced cutaneous toxicity has not been clarified, leading to the lack of an effective strategy to improve clinical safety. Here, we found that lapatinib could induce mitochondrial dysfunction, lead to DNA damage and ultimately cause apoptosis of keratinocytes. In addition, we found that lapatinib could induce an aberrant immune response and promote the release of inflammatory factors in vitro and in vivo. Mechanistically, downregulated expression of the DNA repair protein HMGB1 played a critical role in these toxic reaction processes. Overexpression of HMGB1 inhibited keratinocyte apoptosis and inflammatory reactions. Therefore, restoring HMGB1 expression might be an effective remedy against lapatinib-induced cutaneous toxicity. Finally, we found that saikosaponin A could significantly rescue the reduced HMGB1 transcription, which could alleviate lapatinib-induced DNA damage, inhibit keratinocyte apoptosis and further prevent the toxicity of lapatinib in mice. Collectively, our study might bring new hope to clinicians and tumor patients and shed new light on the prevention of cutaneous adverse drug reactions induced by EGFR inhibitors.

Treatment of Androgenetic Alopecia Using PRP to Target Dysregulated Mechanisms and Pathways

Androgenetic alopecia (“AGA”) is the most prevalent type of progressive hair loss, causing tremendous psychological and social stress in patients. However, AGA treatment remains limited in scope. The pathogenesis of androgenetic alopecia is not completely understood but is known to involve a hair follicle miniaturization process in which terminal hair is transformed into thinner, softer vellus-like hair. This process is related to the dysregulation of the Wnt/β-catenin signaling pathway, which causes premature termination of the anagen growth phase in hair follicles. Historically used for wound healing, platelet rich plasma (“PRP”) has recently been at the forefront of potential AGA treatment. PRP is an autologous preparation of plasma that contains a high number of platelets and their associated growth factors such as EGF, IGF-1, and VEGF. These factors are known to individually play important roles in regulating hair follicle growth. However, the clinical effectiveness of PRP is often difficult to characterize and summarize as there are wide variabilities in the PRP preparation and administration protocols with no consensus on which protocol provides the best results. This study follows the previous review from our group in 2018 by Cervantes et al. to analyze and discuss recent clinical trials using PRP for the treatment of AGA. In contrast to our previous publication, we include recent clinical trials that assessed PRP in combination or in direct comparison with standard of care procedures for AGA such as topical minoxidil and/or oral finasteride. Overall, this study aims to provide an in-depth analysis of PRP in the treatment of AGA based on the evaluation of 17 recent clinical trials published between 2018 and October 2021. By closely examining the methodologies of each clinical trial included in our study, we additionally aim to provide an overall consensus on how PRP can be best utilized for the treatment of AGA.

The Role of Pre-treatment Inflammatory Biomarkers in the Prediction of an Early Response to Panitumumab in Metastatic Colorectal Cancer

Background Systemic inflammation is a critical component of the development and progression of several types of cancer. Neutrophil-lymphocyte ratio (NLR) and lymphocyte-monocyte ratio (LMR) are simple, inexpensive, and reliable predictors of the systemic inflammatory response to the therapy in different malignant tumors, including colorectal cancer. Methods Metastatic colorectal cancer (mCRC) patients treated with panitumumab plus chemotherapy at first-line at the medical oncology unit of Fondazione Institute for Research, Hospitalization and Health Care (IRCCS) Policlinico San Matteo di Pavia between January 1st 2016 and February 1st 2021 were retrospectively analyzed. NLR and LMR were divided into two groups (high and low) based on the cut-off points, with the estimation of the prognostic accuracy of NLR for the early treatment response as the primary end-point of this study. Results The receiver operating characteristic (ROC) analysis showed a fair prognostic accuracy of NLR for early treatment response (area under the curve (AUC)=0.76, 95% CI: 0.62-0.89). A slightly lower prognostic accuracy was found for LMR (AUC=0.71, 95% CI: 0.57-0.85). In the univariable proportional hazard Cox model, no effect of NLR on PFS was found (NLRHigh vs. NLRLow HR=1.3; 95% CI: 0.7-2.4, p=0.414). Patients with higher levels of LMR showed a trend towards higher PFS (LMRHigh vs. LMRLow HR=0.4; 95% CI: 0.2-1.1, p=0.066). No association was found between NLR (or LMR) and skin toxicity. Conclusions NLR and LMR may be used as biomarkers of prognostic accuracy for the early treatment response in mCRC patients treated with panitumumab.

Remodeling of dermal adipose tissue alleviates cutaneous toxicity induced by anti-EGFR therapy

Anti-epidermal growth factor receptor (EGFR) therapy–associated cutaneous toxicity is a syndrome characterized by papulopustular rash, local inflammation, folliculitis, and microbial infection, resulting in a decrease in quality of life and dose interruption. However, no effective clinical intervention is available for this adverse effect. Here, we report the atrophy of dermal white adipose tissue (dWAT), a highly plastic adipose tissue with various skin-specific functions, correlates with rash occurrence and exacerbation in a murine model of EGFR inhibitor-induced rash. The reduction in dWAT is due to the inhibition of adipogenic differentiation by defects in peroxisome proliferator-activated receptor γ (PPARγ) signaling, and increased lipolysis by the induced expression of the lipolytic cytokine IL6. The activation of PPARγ by rosiglitazone maintains adipogenic differentiation and represses the transcription of IL6, eventually improving skin functions and ameliorating the severity of rash without altering the antitumor effects. Thus, activation of PPARγ represents a promising approach to ameliorate cutaneous toxicity in patients with cancer who receive anti-EGFR therapy.

Reducing Acneiform Rash Induced by EGFR Inhibitors With Honeysuckle Therapy: A Prospective, Randomized, Controlled Study

Background: Epidermal growth factor receptor inhibitors (EGFRIs), including cetuximab, erlotinib, gefitinib and icotinib, have been proven to be effective in treating colorectal cancer or lung cancer. However, most of patients who receive EGFRIs treatment experience cutaneous toxicities, such as acneiform or papulopustular rashes, which affects quality of life and leads to discontinuation of cancer therapies. Honeysuckle is a traditional herb historically used to treat skin rash for thousands of years in Eastern Asia and showed proven safety in human.

Methods: To investigate whether honeysuckle therapy could control EGFRIs induced acneiform rashes, a total of 139 colorectal and lung cancer patients with EGFRIs treatments were recruited in a prospective study. Patients were randomized to 3 arms (Arm A: prophylactic treatment with honeysuckle before rash occurred; Arm B: symptomatic treatment with honeysuckle when rash occurred; Arm C: conventional treatment with minocycline and a topical solution when rash occurred). The incidences, severities and recovery time of acneiform rash were observed in each arm.

Results: Honeysuckle treatment reduced incidences of EGFRIs induced acneiform rash, which were 56.5, 68.1 and 71.7% in Arm A, B and C, respectively (p = 0.280). Severities of rash (CTCAE grade 2 and 3) were significantly lower in prophylactic honeysuckle treatment (Arm A) compared to conventional treatment (Arm C) (p = 0.027), which was 10–21%, respectively. Patients with honeysuckle treatment recovered more quickly from pruritus, the median time was 22, 36 and 58 days in Arm A, B and C, respectively (p = 0.016).

Conclusion: Honeysuckle was effective in reducing incidences and severities of EGFRIs induced acneiform rash, especially for prophylactic treatment.

Streptococcal pyrogenic exotoxin B cleaves GSDMA and triggers pyroptosis

Gasdermins, a family of five pore-forming proteins (GSDMA-GSDME) in humans expressed predominantly in the skin, mucosa and immune sentinel cells, are key executioners of inflammatory cell death (pyroptosis), which recruits immune cells to infection sites and promotes protective immunity1,2. Pore formation is triggered by gasdermin cleavage1,2. Although the proteases that activate GSDMB, C, D and E have been identified, how GSDMA-the dominant gasdermin in the skin-is activated, remains unknown. Streptococcus pyogenes, also known as group A Streptococcus (GAS), is a major skin pathogen that causes substantial morbidity and mortality worldwide3. Here we show that the GAS cysteine protease SpeB virulence factor triggers keratinocyte pyroptosis by cleaving GSDMA after Gln246, unleashing an active N-terminal fragment that triggers pyroptosis. Gsdma1 genetic deficiency blunts mouse immune responses to GAS, resulting in uncontrolled bacterial dissemination and death. GSDMA acts as both a sensor and substrate of GAS SpeB and as an effector to trigger pyroptosis, adding a simple one-molecule mechanism for host recognition and control of virulence of a dangerous microbial pathogen.

Unraveling the differential impact of PAHs and dioxin-like compounds on AKR1C3 reveals the EGFR extracellular domain as a critical determinant of the AHR response

Polycyclic aromatic hydrocarbons (PAHs), dioxin-like compounds (DLCs) and structurally-related environmental pollutants may contribute to the pathogenesis of various diseases and disorders, primarily by activating the aryl hydrocarbon receptor (AHR) and modulating downstream cellular responses. Accordingly, AHR is considered an attractive molecular target for preventive and therapeutic measures. However, toxicological risk assessment of AHR-modulating compounds as well as drug development is complicated by the fact that different ligands elicit remarkably different AHR responses. By elucidating the differential effects of PAHs and DLCs on aldo-keto reductase 1C3 expression and associated prostaglandin D₂ metabolism, we here provide evidence that the epidermal growth factor receptor (EGFR) substantially shapes AHR ligand-induced responses in human epithelial cells, i.e. primary and immortalized keratinocytes and breast cancer cells. Exposure to benzo[a]pyrene (B[a]P) and dioxin-like polychlorinated biphenyl (PCB) 126 resulted in a rapid c-Src-mediated phosphorylation of EGFR. Moreover, both AHR agonists stimulated protein kinase C activity and enhanced the ectodomain shedding of cell surface-bound EGFR ligands. However, only upon B[a]P treatment, this process resulted in an auto-/paracrine activation of EGFR and a subsequent induction of aldo-keto reductase 1C3 and 11-ketoreduction of prostaglandin D₂. Receptor binding and internalization assays, docking analyses and mutational amino acid exchange confirmed that DLCs, but not B[a]P, bind to the EGFR extracellular domain, thereby blocking EGFR activation by growth factors. Finally, nanopore long-read RNA-seq revealed hundreds of genes, whose expression is regulated by B[a]P, but not by PCB126, and sensitive towards pharmacological EGFR inhibition. Our data provide novel mechanistic insights into the ligand response of AHR signaling and identify EGFR as an effector of environmental chemicals.

Selective Immune Modulating Activities of Viscum album and Its Components; A Possibility of Therapeutics on Skin Rash Induced by EGFR Inhibitors

Viscum album var. coloratum (Kom.) Ohwi is a traditional herbal medicine used in East Asia to treat hypertension, skeletal muscle disorders, and cancer. The inhibitory effects of Viscum album (VA) extract on chemokines and its therapeutic potential in erlotinib-induced skin rash were investigated in this study. ELISA was used to measure the levels of chemokines, MCP-1 and RANTES, which are thought to be mediators of erlotinib-induced skin rash in RAW264.7 cells. Western blot analysis was used to look into the activation of signaling pathways like AKT, MAPK, and EGF. In order to investigate the active compounds in VA extract, solvent fractionation and preparative HPLC were performed sequentially. VA extract significantly reduced the production of TNF-α, MCP-1, and RANTES but not IL-1. Furthermore, macrophage transmigration was inhibited without causing cell toxicity. VA extract had no effect on the phosphorylation of EGF receptors stimulated by EGF or suppressed by erlotinib in both A549, a non-small cell lung cancer cells, and Hacat, a human skin keratinocyte. The isolated viscumneoside III and viscumneoside V from VA extract significantly suppressed the expression of MCP-1, according to activity guided fractionation with organic solvent fractionation and preparative HPLC. These findings suggest that VA extract and its active compounds, viscumneoside III and viscumneoside V, regulate MCP-1 production and may have the potential to suppress erlotinib-induced skin toxicity by modulating macrophage activity without neutralizing anti-cancer efficacy.

Topical Zhiyang Pingfu Liquid for Moderate to Severe Skin Rash Associated With EGFRIs: A double-blinded randomized controlled trial

BACKGROUND

Skin rash is the most common adverse effect associated with epidermal growth factor receptor inhibitors (EGFRIs). The study has observed the efficacy and safety of Zhiyang Pingfu Liquid in the treatment of EGFRIs-related moderate and severe rash.

METHODS

Patients suffering from EGFRIs-related moderate to severe rash were enrolled and then randomly divided into the treatment group and the control group, receiving Zhiyang Pingfu Liquid and placebo liquid respectively combined with minocycline and methylprednisolone recommended by guideline for 14 days. Changes in rash grades were observed, as well as the dosage of minocycline. Blood routine examination and liver and kidney function were evaluated to observe the safety of Zhiyang Pingfu Liquid. The total response of rash included complete response (CR) and partial response (PR). And the effective rate of rash was the percentage of CR and PR in the total cases.

RESULTS

A total of 54 out of 58 patients finished the study with 27 patients in each group. The effective rates of rash among the treatment group and the control group were 81.48% and 55.56% after 14 days treatment (P = .040). The treatment group had a lower dosage of minocycline compared with the control group. The median total dose of oral minocycline administration was 1000 mg in the treatment group and 1400 mg in the control group.

CONCLUSION

Zhiyang Pingfu Liquid can effectively improve the moderate and severe EGFRIs-induced rash, and reduce the use of minocycline, as well as the side reactions brought by minocycline. However, larger randomized controlled trials are needed to verify these findings.

CLINICAL TRIAL REGISTRATION

The trial was registered on the Chinese Clinical Trial Registry, the registration number is ChiCTR1800017053.

Unlocking the Mechanisms of Cutaneous Adverse Drug Reactions: Activation of the Phosphatidylinositol 3-Kinase/Protein Kinase B Pathway by EGFR Inhibitors Triggers Keratinocyte Differentiation and Polarization of Epidermal Immune Responses

EGFR inhibitors used in oncology therapy modify the keratinocyte differentiation processes, impairing proper skin barrier formation and leading to cutaneous adverse drug reactions. To uncover the molecular signatures associated with cutaneous adverse drug reactions, we applied phosphoproteomic and transcriptomic assays on reconstructed human epidermis tissues exposed to a therapeutically relevant concentration of afatinib, a second-generation EGFR inhibitor. After drug exposure, we observed activation of the phosphatidylinositol 3-kinase/protein kinase B pathway associated with an increased expression of gene families involved in keratinocyte differentiation, senescence, oxidative stress, and alterations in the epidermal immune-related markers. Furthermore, our results show that afatinib may interfere with vitamin D3 metabolism, acting via CYP27A1 and CYP24A1 to regulate calcium concentration through the phosphatidylinositol 3-kinase/protein kinase B pathway. Consequently, basal layer keratinocytes switch from a pro-proliferating to a prodifferentiative program, characterized by upregulation of biomarkers associated with increased keratinization, cornification, T helper type 2 response, and decreased innate immunity. Such effects may increase skin susceptibility to cutaneous penetration of irritants and pathogens. Taken together, these findings demonstrate a molecular mechanism of EGFR inhibitor–induced cutaneous adverse drug reactions.

Drug eruptions with novel targeted therapies - immune checkpoint and EGFR inhibitors

Given the increasing use of novel targeted therapies, dermatologists are constantly confronted with novel cutaneous side effects of these agents. A rapid diagnosis and appropriate management of these side effects are crucial to prevent impairment of the patients' quality of life and interruptions of essential cancer treatments. Immune checkpoint and EGFR inhibitors are frequently used targeted therapies for various malignancies and are associated with a distinct spectrum of cutaneous adverse events. Exanthematous drug eruptions represent a particular diagnostic challenge in these patients. Immune checkpoint inhibitors can elicit a plethora of immune-related exanthemas, most commonly maculopapular, lichenoid, and psoriasiform eruptions. Additionally, autoimmune bullous dermatoses and exanthemas associated with connective tissue diseases may arise. In cases of severe, atypical or therapy-resistant presentations an extensive dermatological investigation including a skin biopsy is recommended. Topical and systemic steroids are the mainstay of treatment. Papulopustular eruptions represent the major cutaneous adverse effect of EGFR inhibitor therapy, occurring in up to 90 % of patients within the first two weeks of therapy, depending on the agent. Besides topical antibiotics and steroids, oral tetracyclines are the first choice in systemic treatment and can also be used as prophylaxis.

Ex-Vivo Skin Explant Culture Is a Model for TSLP-Mediated Skin Barrier Immunity

The skin is the outermost barrier protecting the body from pathogenic invasion and environmental insults. Its breakdown initiates the start of skin inflammation. The epidermal growth factor (EGFR) on keratinocytes protects this barrier, and its dysfunction leads to atopic dermatitis-like skin disease. One of the initial cytokines expressed upon skin barrier breach and during atopic dermatitis is TSLP. Here, we describe the expression and secretion of TSLP during EGFR inhibition and present an ex-vivo model, which mimics the early events after barrier insult. Skin explants floated on culture medium at 32 °C released TSLP in parallel to the activation of the resident Langerhans cell network. We could further show the up-regulation and activation of the AP-1 family of transcription factors during atopic-like skin inflammation and its involvement in TSLP production from the skin explant cultures. Inhibition of the c-Jun N-terminal kinase pathway led to a dose-dependent blunting of TSLP release. These data indicate the involvement of AP-1 during the early stages of atopic-like skin inflammation and highlight a novel therapeutic approach by targeting it. Therefore, skin explant cultures mimic the early events during skin barrier immunity and provide a suitable model to test therapeutic intervention.

A multicenter study of skin toxicity management in patients with left-sided, RAS/BRAF wild-type metastatic colorectal cancer treated with first-line anti-EGFR-based doublet regimen: is there room for improvement?

BACKGROUND

Skin toxicity in patients affected by metastatic colorectal cancer (mCRC) treated with epidermal growth factor receptor (EGFR) inhibitors is well known. However, ad hoc ESMO guidelines have only recently been published.

AIM AND METHODS

To describe the management (pre-emptive or reactive) of anti-EGFR-related cutaneous adverse events (AEs), in a real-life clinical context, in a selected population of patients with left-sided, metastatic RAS/BRAF wild-type mCRC treated with doublet chemotherapy plus anti-EGFR monoclonal antibody (i.e., panitumumab or cetuximab) as first-line regimen at 22 Institutions. The measured clinical outcomes were treatment-related adverse events, objective response rate (ORR), progression-free survival (PFS), and overall survival (OS).

RESULTS

Of 515 patients included in the analysis, 173 (33.6%) received a pre-emptive and 342 (66.4%) a reactive treatment. The median follow-up period for the overall population was 30.0 months. A significantly lower incidence of any grade acneiform rash was found in the pre-emptive compared to the reactive cohort both in the overall population (78.6% vs 94.4%, p < 0.001) and in patients treated with panitumumab (76.1% vs 93.7%, p < 0.001) or cetuximab (83.3% vs 95.4%, p = 0.004), respectively. A lower incidence of any grade (41.6% vs 50.9%, p = 0.047) but a higher incidence of G3-G4 (9.2% vs 4.7%, p = 0.042) paronychia/nail disorders were found in the pre-emptive compared to the reactive cohort. Nevertheless, a lower rate of patients within the reactive compared to the pre-emptive cohort was referred to dermatological counseling (21.4% vs 15.3%, respectively, p = 0.001). A higher rate of anti-EGFR therapy modification was needed in the pre-emptive compared to the reactive cohort (35.9% vs 41.6%, respectively, p < 0.001). The pre-emptive approach did not reduce the efficacy of antineoplastic therapy compared to the reactive in terms of ORR (69.2% vs 72.8%), median PFS (12.3 vs 13.0 months), and median OS (28.8 vs 33.5 months).

CONCLUSION

Although recommended by international guidelines, the pre-emptive approach of anti-EGFR-related skin toxicity in mCRC patients still appears less adopted in daily clinical practice, compared to the reactive one. A wider reception and application of this indication is desirable to improve patients' quality of life without compromising the continuity and efficacy of antineoplastic therapy.

Desmosomes as Signaling Hubs in the Regulation of Cell Behavior

Desmosomes are intercellular junctions, which preserve tissue integrity during homeostatic and stress conditions. These functions rely on their unique structural properties, which enable them to respond to context-dependent signals and transmit them to change cell behavior. Desmosome composition and size vary depending on tissue specific expression and differentiation state. Their constituent proteins are highly regulated by posttranslational modifications that control their function in the desmosome itself and in addition regulate a multitude of desmosome-independent functions. This review will summarize our current knowledge how signaling pathways that control epithelial shape, polarity and function regulate desmosomes and how desmosomal proteins transduce these signals to modulate cell behavior.

Epithelial-immune crosstalk with the skin microbiota in homeostasis and atopic dermatitis - a mini review

The skin is a complex and dynamic ecosystem, wherein epithelial cells, immune cells and the skin microbiota actively interact and maintain barrier integrity and functional immunity. Skin microbes actively tune the functions of the resident immune cells. Dysbiosis - alterations in the resident microbiota - leads to the dysregulation of host immunity. Microbiome analyses in humans and dogs with atopic dermatitis (AD) have shown shifts in microbial diversity, and in particular, an increased proportion of staphylococci. Monogenic diseases that manifest AD-like symptoms provide insights into the pathogenesis of AD and the mechanisms of dysbiosis, from both the epithelial and immunological perspectives. The symbiotic relationships between the host and microbiota must be maintained constitutively. Detailed mechanisms of how host immunity regulates commensal bacteria in the steady state have been reported. The skin harbours multiple tissue-resident immune cells, including both innate and adaptive immune cells. Recent studies have highlighted the fundamental role of innate lymphoid cells (ILCs) in the maintenance of barrier functions and tissue homeostasis. ILCs directly respond to tissue-derived signals and are instrumental in barrier immunity. Epithelial cells produce alarmins such as thymic stromal lymphopoietin (TSLP) and interleukins (IL)-33 and IL-25, all of which activate group 2 ILCs (ILC2s), which produce type 2 cytokines, such as IL-5 and IL-13, boosting type 2 immune reactions. Dysregulation of the epithelial-ILC crosstalk results in allergic inflammation. This review highlights our understanding of the active interactions between the host epithelial and immune cells, and microbiota, providing a foundation for novel therapeutic strategies for inflammatory skin diseases.