Layer Keratinocytes Research Articles

The Incorporation of Melanosomes by Senescent Keratinocytes Causes the Accumulation of Melanin due to Decreased Energy Metabolism

ABSTRACTIn solar lentigo, a typical age‐related pigmentary disorder of the skin, abundant melanin is deposited in the basal layer of keratinocytes and not spontaneously eliminated. The reason for the prolonged melanin accumulation in keratinocytes is not fully understood. Therefore, we focused on the energy metabolism of keratinocytes that incorporate melanosomes, specialized organelles where melanin pigment is synthesized, and investigated the mechanism of melanin accumulation in keratinocytes. Energy metabolism in keratinocytes after the addition of melanosomes was assessed by measuring ATP levels, lactate production, and oxygen consumption rate. Energy limitations after melanosome addition were evaluated by microscopy. Cells with incorporated melanosomes were stained for senescence and proliferation markers. The results showed that keratinocytes upregulated their energy metabolism after melanosome incorporation and energy limitations increased the amount of melanin per cell. Keratinocytes positive for senescence‐associated β‐galactosidase, a cellular senescence marker, accumulated large amounts of melanin, while keratinocytes positive for 5‐ethynyl‐2′‐deoxyuridine, a proliferation marker, contained little melanin. These findings indicate that senescent keratinocytes tend to accumulate melanin, which may be due to their impaired energy metabolism and thus inability to activate energy metabolism after melanosome incorporation. Our results suggest that melanosome incorporation by senescent keratinocytes causes the persistent melanin deposition in solar lentigo.

Immunohistochemical Expression of Immune Regulatory Proteins in Interface Dermatoses.

Cutaneous immune-related adverse events (irAEs) of immunotherapies, such as anti-programmed cell death protein-1 (PD-1), suggest that immune checkpoint factors may contribute to the pathobiology of lichenoid interface dermatitis in immunotherapy-naïve patients. Our study aimed to describe innate and adaptive immune markers via immunohistochemical (IHC) staining of lichenoid interface dermatoses. We studied the staining patterns of PD-L1, STING, IL-36 gamma, CD8, PD-1, and LAG-3 in five interface dermatoses: oral lichen planus (LP) (n = 10), cutaneous LP (n = 10), chronic cutaneous lupus erythematosus (CLE) (n = 11), erythema multiforme (EM) (n = 11), and toxic epidermal necrolysis (TEN) (n = 13), by immunohistochemistry (IHC) analysis. Expression was evaluated semi-quantitively according to the percentage of keratinocytes and dermal lymphocytes stained compared to keratinocytes and resident pericapillary lymphocytes in normal human skin. All interface dermatoses evaluated showed increased expression of PD-L1 on keratinocytes and LAG-3 in lymphocytes. STING was increased on the keratinocytes of most specimens. Expression of IL-36 gamma, in basal layer keratinocytes was more extensive in oral LP and cutaneous LP and varied in CLE, EM, and TEN. Lymphocytic infiltration expressing PD-1 was elevated in oral LP, cutaneous LP, and CLE. Current thinking is that interface dermatitis is the result of a cell-mediated immune reaction involving cytotoxic CD8+ T-cell-mediated apoptosis of keratinocytes. The findings of this study suggest that in addition to cell-mediated immunity, innate immune factors may contribute to pathobiology.

Assessing Barrier Function in Psoriasis and Cornification Models of Artificial Skin Using Non-Invasive Impedance Spectroscopy.

Reconstructed epidermal equivalents (REEs) consist of two distinct cell layers - the stratum corneum (SC) and the keratinocyte layer (KL). The interplay of these layers is particularly crucial in pruritic inflammatory disorders, like psoriasis, where a defective SC barrier is associated with immune dysregulation. However, independent evaluation of the skin barrier function of the SC and KL in REEs is highly challenging because of the lack of quantitative methodologies that do not disrupt the counter layer. Here, a non-invasive impedance spectroscopy technique is introduced for dissecting the distinct contributions of the SC and KL to overall skin barrier function without disrupting the structure. These findings, inferred from the impedance spectra, highlight the individual barrier resistances and maturation levels of each layer. Using an equivalent circuit model, a correlation between impedance parameters and specific skin layers, offering insights beyond traditional impedance methods that address full-thickness skin only is established. This approach successfully detects subtle changes, such as increased paracellular permeability due to mild irritants and the characterization of an immature SC in psoriatic models. This research has significant implications, paving the way for detailed mechanistic investigations and fostering the development of therapies for skin irritation and inflammatory disorders.

Live imaging in zebrafish reveals tissue-specific strategies for amoeboid migration.

Amoeboid cells like leukocytes can enter and migrate within virtually every tissue of the body, even though tissues vary widely in their chemical and mechanical composition. Here, we imaged motile T cells as they colonized peripheral tissues during zebrafish development to ask if cells tailor their migration strategy to their local tissue environment. We found that T cells in most sites migrated with f-actin-rich leading-edge pseudopods, matching how they migrate in vitro . T cells notably deviated from this strategy in the epidermis, where they instead migrated using a rearward concentration of f-actin and stable leading-edge blebs. This mode of migration occurs under planar confinement in vitro , and we correspondingly found the stratified keratinocyte layers of the epidermis impose planar-like confinement on leukocytes in vivo . By imaging the same cell type across the body, our data collectively indicates that cells adapt their migration strategy to navigate different tissue geometries in vivo .

Keratinocytes drive the epithelial hyperplasia key to sea lice resistance in coho salmon

BackgroundSalmonid species have followed markedly divergent evolutionary trajectories in their interactions with sea lice. While sea lice parasitism poses significant economic, environmental, and animal welfare challenges for Atlantic salmon (Salmo salar) aquaculture, coho salmon (Oncorhynchus kisutch) exhibit near-complete resistance to sea lice, achieved through a potent epithelial hyperplasia response leading to rapid louse detachment. The molecular mechanisms underlying these divergent responses to sea lice are unknown.ResultsWe characterized the cellular and molecular responses of Atlantic salmon and coho salmon to sea lice using single-nuclei RNA sequencing. Juvenile fish were exposed to copepodid sea lice (Lepeophtheirus salmonis), and lice-attached pelvic fin and skin samples were collected 12 h, 24 h, 36 h, 48 h, and 60 h after exposure, along with control samples. Comparative analysis of control and treatment samples revealed an immune and wound-healing response that was common to both species, but attenuated in Atlantic salmon, potentially reflecting greater sea louse immunomodulation. Our results revealed unique but complementary roles of three layers of keratinocytes in the epithelial hyperplasia response leading to rapid sea lice rejection in coho salmon. Our results suggest that basal keratinocytes direct the expansion and mobility of intermediate and, especially, superficial keratinocytes, which eventually encapsulate the parasite.ConclusionsOur results highlight the key role of keratinocytes in coho salmon’s sea lice resistance and the diverged biological response of the two salmonid host species when interacting with this parasite. This study has identified key pathways and candidate genes that could be manipulated using various biotechnological solutions to improve Atlantic salmon sea lice resistance.

Chondroitin sulfate proteoglycan 4 increases invasion of recessive dystrophic epidermolysis bullosa-associated cutaneous squamous cell carcinoma by modifying transforming growth factor-β signalling.

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare genetic skin-blistering disorder that often progresses to metastatic cutaneous squamous cell carcinoma (cSCC) at chronic wound sites. Chondroitin sulfate proteoglycan 4 (CSPG4) is a cell-surface proteoglycan that is an oncoantigen in multiple malignancies, where it modulates oncogenic signalling, drives epithelial-to-mesenchymal transition (EMT) and enables cell motility. To evaluate CSPG4 expression and function in RDEB cSCC. RDEB cSCC cell lines were used to assess CSPG4-dependent changes in invasive potential, transforming growth factor (TGF)-β1-stimulated signal activation and clinically relevant cytopathology metrics in an in vitro full-thickness tumour model. CSPG4 expression in RDEB cSCC and non-RDEB cSCC tumours was analysed via immunohistochemistry and single-cell RNA sequencing (scRNA-Seq), respectively. Inhibiting CSPG4 expression reduced invasive potential in multiple RDEB cSCC cell lines and altered membrane-proximal TGF-β signal activation via changes in SMAD3 phosphorylation. CSPG4 expression was uniformly localized to basal layer keratinocytes in fibrotic RDEB skin and tumour cells at the tumour-stroma interface at the invasive front in RDEB cSCC tumours in vivo. Analysis of published scRNA-Seq data revealed that CSPG4 expression was correlated with an enhanced EMT transcriptomic signature in cells at the tumour-stroma interface of non-RDEB cSCC tumours. Cytopathological metrics, for example nucleus : cell area ratio, were influenced by CSPG4 expression in in vitro tumour models. We determined that CSPG4 expression in RDEB cSCC cell lines enhanced the invasive potential of tumours. Mechanistically, CSPG4 was found to enhance membrane-proximal TGF-β-stimulated signalling via SMAD3, which is a key mediator of EMT in RDEB cSCC. The implication of these studies is that CSPG4 may represent a therapeutic target that can be leveraged for the clinical management of patients with RDEB cSCC.

PRSS3/mesotrypsin as a putative regulator of the biophysical characteristics of epidermal keratinocytes in superficial layers

Mesotrypsin, encoded by the PRSS3 gene, is a distinctive trypsin isoform renowned for its exceptional resistance to traditional trypsin inhibitors and unique substrate specificity. Within the skin epidermis, this protein primarily expresses in the upper layers of the stratified epidermis and plays a crucial role in processing pro-filaggrin (Pro-FLG). Although prior studies have partially elucidated its functions using primary cultured keratinocytes, challenges persist due to these cells' differentiation-activated cell death program. In the present study, HaCaT keratinocytes, characterized by minimal endogenous mesotrypsin expression and sustained proliferation in differentiated states, were utilized to further scrutinize the function of mesotrypsin. Despite the ready degradation of the intact form of active mesotrypsin in these cells, fusion with Venus, flanked by a peptide linker, enables evasion from the protein elimination machinery, thus facilitating activation of the Pro-FLG processing system. Inducing Venus-mesotrypsin expression in the cells resulted in a flattened phenotype and reduced proliferative capacity. Moreover, these cells displayed altered F-actin assembly, enhanced E-cadherin adhesive activity, and facilitated tight junction formation without overtly influencing epidermal differentiation. These findings underscore mesotrypsin's potentially pivotal role in shaping the characteristic cellular morphology of upper epidermal layers.

Models of the Three-Component Bilayer of Stratum Corneum: A Molecular Simulation Study.

The construction of the stratum corneum (SC) is crucial to the problems of transdermal drug delivery. SC consists of the keratinocyte layers and the lipid matrix surrounding it. Among them, the lipid matrix is the barrier for many exogenous molecules, mainly composed of ceramides (CERs), free fatty acids (FFA), and cholesterol (CHOL). In this work, we developed single-component (CERs, CER-NS, and CER-EOS) and six three-component models, and each model was simulated by using the GROMOS-54A7 force field. Short-period phase (SPP) and long-period phase (LPP) systems were established separately, and area per lipid (APL), thickness, order of carbon chain (SCD), and density distribution were analyzed. The transition of CER-NS and CER-EOS in LPP was observed. The results of hydrogen bonds in the lipid systems indicated that a strong hydrogen-bond network was formed between the skin-lipid bilayers. Umbrella sampling method simulations were performed to calculate the free energy change of ethanol moving into the skin-lipid bilayer. The results revealed that ethanol molecules pulled some water molecules into the membrane when they passed through SPP-1. Our findings provided some insights and models of the stratum corneum that could be used for the subsequent mechanism of macromolecule permeation through membranes in drugs, cosmetics, and so on.

3D Bioprinted Human Skin Model Recapitulating Native-Like Tissue Maturation and Immunocompetence as an Advanced Platform for Skin Sensitization Assessment.

Physiologically-relevant in vitro skin models hold the utmost importance for efficacy assessments of pharmaceutical and cosmeceutical formulations, offering valuable alternatives to animal testing. Here, an advanced immunocompetent 3D bioprinted human skin model is presented to assess skin sensitization. Initially, a photopolymerizable bioink is formulated using silk fibroin methacrylate, gelatin methacrylate, and photoactivated human platelet releasate. The developed bioink shows desirable physicochemical and rheological attributes for microextrusion bioprinting. The tunable physical and mechanical properties of bioink are modulated through variable photocuring time for optimization. Thereafter, the bioink is utilized to 3D bioprint "sandwich type" skin construct where an artificial basement membrane supports a biomimetic epidermal layer on one side and a printed pre-vascularized dermal layer on the other side within a transwell system. The printed construct is further cultured in the air-liquid interface for maturation. Immunofluorescence staining demonstrated a differentiated keratinocyte layer and dermal extracellular matrix (ECM)-remodeling by fibroblasts and endothelial cells. The biochemical estimations and gene-expression analysis validate the maturation of the printed model. The incorporation of macrophages further enhances the physiological relevance of the model. This model effectively classifies skin irritative and non-irritative substances, thus establishing itself as a suitable pre-clinical screening platform for sensitization tests.

Abstract 346: Trop-2 induces apoptosis via transcriptional activation of TRAIL, FAS-FASL, CD40-TNFRSF5

Abstract Trop-2 is a transmembrane signal transducer that activates cancer growth and metastatic diffusion (1). However, this does not occur in all tumor types, as Trop-2 is associated to better disease outcome in some cancers, e.g. breast and lung tumors. A prototypic pattern of Trop-2 expression in normal multistratified epithelia, e.g. epidermis, esophagus, is that of preferential expression in non-proliferating, terminally differentiated cells. The corresponding expression gradient parallels that of induction of programmed cell death, e.g. in the corneum layer of skin keratinocytes. This led us to explore Trop-2 function as a trigger of apoptosis. We thus assessed NS-0 myeloma Trop-2 transfectants for apoptosis induction by dynamic cell morphometry and quantification of membrane blebbing and cell fragmentation. This was shown to be preceded by phosphatidyl-serine membrane exposure, and was followed by nuclear pyknosis and karyorrhexis. DNA fragmentation was shown by TUNEL and DNA laddering, and was accompanied by a dramatic increase of apoptotic death of Trop-2-expressing cells. Transcriptomic analysis at early time points of apoptosis induction indicated overexpression of TRAIL, FAS/FASL and CD40/TNFRSF5 transmembrane death receptors. This paralleled upregulation of downstream death-inducing signaling complex components and of executioner Caspases 8 and 3, suggesting Trop-2 as a trigger of extrinsic apoptosis pathways. Apoptosis induction translated into diminished tumor growth in vivo, which was shown to be proportional to Trop-2 expression levels. However, apoptosis induction was found to parallel stimulation of NS-0 cell growth and of defence mechanisms from apoptosis, as increased levels of inhibitory transcription factors, Rb-binding protein, survivin, Myd-118. These findings suggest a previously unappreciated balance between stimulation of cell growth and triggering of cell death by Trop-2, and may pave the way for selective anticancer therapy approaches in Trop-2-expressing cancers.(1) Trerotola M. et al., Neoplasia 23: 415-428 (2021). Citation Format: Saverio Alberti, Emanuela Guerra, Antonino Moschella, Martina Ceci, Ludovica Pantalone, Roberta Di Pietro, Marco Trerotola. Trop-2 induces apoptosis via transcriptional activation of TRAIL, FAS-FASL, CD40-TNFRSF5 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 346.

Recombinant Human Keratinocyte Growth Factor Ameliorates Cancer Treatment-Induced Oral Mucositis on a Chip.

Oral mucositis (OM) is a severe complication of cancer therapies caused by off-target cytotoxicity. Palifermin, which is recombinant human keratinocyte growth factor (KGF), is currently the only mitigating treatment available to a subset of OM patients. This study used a previously established model of oral mucositis on a chip (OM-OC) comprised of a confluent human gingival keratinocytes (GIE) layer attached to a basement membrane-lined subepithelial layer consisting of human gingival fibroblasts (HGF) and human dermal microvascular endothelial cells (HMEC) on a stable collagen I gel. Cisplatin, radiation, and combined treatments are followed by a recovery period in the OM-OC to determine possible cellular and molecular mechanisms of OM under effects of KGF. Cancer treatments affected the keratinocyte layer, causing death and epithelial barrier loss. Both keratinocytes and subepithelial cells died rapidly, as evidenced by propidium iodide staining. In response to radiation exposure, cell death occurred in the apical epithelial layer, predominantly, within 24h. Cisplatin exposure predominantly promoted death of basal epithelial cells within 32-36h. Presence of KGF in OM-OC protected tissues from damage caused by cancer treatments in a dose-dependent manner, being more effective at 10 ng/mL. As verified by F-actin staining and the Alamar Blue assay, KGF contributed to epithelial survival and induced proliferation of GIE and HGF as well as HMEC within 120h. When the expression of eighty inflammatory cytokines is evaluated at OM induction (Day 12) and resolution (Day 18) stages in OM-OC, some cytokines are identified as potential novel therapeutic targets. In comparison with chemoradiation exposure, KGF treatment showed a trend to decrease IL-8 and TNF-a expression at Day 12 and 18, and TGF-β1 at Day 18 in OM-OC. Taken together, these findings support the utility of OM-OC as a platform to model epithelial damage and evaluate molecular mechanisms following OM treatment.

Characterization of the Newborn Epidermis and Adult Hair Follicles Using Whole-Mount Immunofluorescent Staining of Mouse Dorsal Skin.

The mammalian integumentary system, including skin and its appendages, serves as a protective barrier for the body. During development, skin epidermis undergoes rapid cell division and differentiation to form multiple stratified layers of keratinocytes. Concurrently the epidermis also gives rise to hair follicles that invaginate into the dermis. In adult skin, the hair follicle undergoes cyclic regeneration fueled by hair follicle stem cells located in the bulge. Three-dimensional and high-resolution imaging of these structures using whole-mount immunofluorescent staining allows to better characterize epidermal progenitors and stem cells.

Autoantibodies Which Bind to and Activate Keratinocytes in Systemic Sclerosis.

Systemic sclerosis (SSc) is a multisystem connective tissue disease characterised by pathological processes involving autoimmunity, vasculopathy and resultant extensive skin and organ fibrosis. Recent studies have demonstrated activation and aberrant wound healing responses in the epithelial layer of the skin in this disease, implicating the epithelial keratinocytes as a source of pro-fibrotic and inflammatory mediators. In this paper, we investigated the role of Immunoglobulin G (IgG) autoantibodies directed against epithelial cells, as potential initiators and propagators of pathological keratocyte activation and the ensuing SSc fibrotic cascade. A keratinocyte cell-based ELISA is used to evaluate the binding of SSc IgG. SSc skin biopsies were stained by immunofluorescence for the presence of IgG in the keratinocyte layer. Moreover, IgG purified from SSc sera was evaluated for the potential to activate keratinocytes in tissue culture and to induce TLR2 and 3 signalling in reporter cell lines. We demonstrate enhanced binding of SSc IgG to keratinocytes and the activation of these cells leading to the release of IL-1α, representing a potential initiating pathway in this disease.

Engineering of Uniform Epidermal Layers via Sacrificial Gelatin Bioink-Assisted 3D Extrusion Bioprinting of Skin.

To reconstruct an ideal full-thickness skin model, basal keratinocytes must be distributed as a confluent monolayer on the dermis. However, the currently available extrusion bioprinting method for the skin is limited when producing an air-exposed cellular monolayer because the cells are encapsulated within a bioink. This is the first study to use sacrificial gelatin-assisted extrusion bioprinting to reproduce a uniform and stratified epidermal layer. Experimental analyses of the rheological properties, printability, cell viability, and initial keratinocyte adhesion shows that the optimal gelatin bioink concentration is 4wt.%. The appropriate thickness of the bioprinted gelatin structure for achieving a confluent keratinocyte layer is determined to be 400µm. The suggested strategy generates a uniform keratinocyte monolayer with tight junctions throughout the central and peripheral regions, whereas manual seeding generates non-uniform cellular aggregates and vacancies. These results influence gene expression, exhibiting a propensity for epidermal differentiation. Finally, the gelatin-assisted keratinocytes are bioprinted onto a dermis composed of gelatin methacryloyl and dermis-derived decellularized extracellular matrix to establish a full-thickness skin model. Thus, this strategy leads to significant improvements in epidermal differentiation/stratification. The findings demonstrate that the gelatin-assisted approach is advantageous for recreating reliable full-thickness skin models with significant consistency for mass production.

Protective role of stratum corneum in percutaneous Leptospira infection in a hamster model

Leptospira enters humans and animals through injured skin or mucous membranes by direct or indirect contact with urine excreted from infected reservoirs. Individuals with cut or scratched skin are at high risk of infection and are recommended to be protected from contact with Leptospira, but the risk of infection via skin without apparent wounds is unknown. We hypothesized that the stratum corneum of the epidermis might prevent percutaneous invasion of leptospires.We established a stratum corneum deficient model of hamsters using the tape stripping method. The mortality rate of hamsters lacking stratum corneum that were exposed to Leptospira was higher than that of controls with shaved skin, and was not significantly different from an epidermal wound group. These results indicated that the stratum corneum plays a critical role in protecting the host against leptospiral entry.We also examined the migration of leptospires through the monolayer of HaCaT cells (human keratinocyte cell line) using Transwell. The number of pathogenic leptospires penetrating the HaCaT cell monolayers was higher than that of non-pathogenic leptospires. Furthermore, scanning and transmission electron microscopic observations revealed that the bacteria penetrated the cell monolayers through both intracellular and intercellular routes. This suggested that pathogenic Leptospira can migrate easily through keratinocyte layers and is associated with virulence.Our study further highlights the importance of the stratum corneum as a critical barrier against the invasion of Leptospira found in contaminated soil and water. Hence, preventative measures against contact infection should be taken, even without visible skin wounds.

PA18 Pityriasis rotunda associated with glucose-6-phosphate deficiency in an adolescent boy

Abstract Pityriasis rotunda is an uncommon disorder related to abnormal keratinization, which is characterized clinically by well-defined, scaly, round hypo- or hyperpigmented plaques present over the buttocks, thighs, trunk and lower limbs. It is thought to be a form of acquired ichthyosis. Two types of pityriasis rotunda are often described: type 1, which typically presents in Black and Asian patients > 60 years of age, and is often associated with systemic disease or malignancy; and type 2, which typically presents in patients < 40 years and without associated systemic disease, and may have a familial component. Pityriasis rotunda is particularly rare in children, although case reports have been published in the literature. We present an unusual case of pityriasis rotunda presenting in a 13-year-old boy of Ghanaian descent, with no significant family history. Examination demonstrated typical discrete, hyperpigmented, oval-shaped plaques appearing on the lower limbs and thighs. Biopsy demonstrated typical orthokeratosis, an attenuated granular layer and hyperpigmentation of basal keratinocytes. He was subsequently diagnosed with glucose-6-phosphate dehydrogenase deficiency, which is reported to be associated with pityriasis rotunda. This represents a rare case of pityriasis rotunda presenting in childhood, and may support an association with glucose-6-phosphate dehydrogenase deficiency.

Role of syntaxin3 an apical polarity protein in poorly polarized keratinocytes: regulation of asymmetric barrier formations in the skin epidermis.

The skin epidermis exhibits an asymmetric structure composed of multilayered keratinocytes and those in the outer layers form two-way physical barriers, cornified cell envelope (CCE), and tight junctions (TJs). While undifferentiated keratinocytes in the basal layer continuously deliver daughter cells outward, which undergo successive differentiation with losing their polarized characteristics, they retain the expression of several polarity proteins. In the present study, we revealed that the t-SNARE protein syntaxin3, a critical element for the formation of the apical compartment in simple epithelial cells, is required to confer the ability to organize the physical barriers on "poorly polarized" keratinocytes in epidermal outer layers. HaCaT keratinocytes with genetic ablation of syntaxin3 readily succumbed to hydrogen peroxide-induced cell death. Additionally, they lost the ability to organize TJ and CCE structures, accompanied by notable downregulation of transglutaminase1 and caspase14 (a cornification regulator) expression. These syntaxin3-knockout cells appeared to restore oxidative stress tolerance and functional TJ formation ability, in response to the inducible re-expression of exogenous syntaxin3. While plausible mechanisms underlying these phenomena remain unclear, syntaxin3, an apical polarity protein in the simple epithelia, has emerged as a potentially crucial element for barrier formation in poorly polarized keratinocytes in polarized epidermal tissue.

Novel applications of Cold Atmospheric Plasma for the treatment of Plaque Psoriasis

Plasma is the fourth state of matter other than solid, liquid and gases. About 99 percent of mixture of free positive negative charges, neutral particles and photons. The plasma exists in two forms: hot plasma and cold plasma. Hot plasma is used in metallurgical operations while cold plasma is used in medical, skin psoriasis treatment, food agricultural, preservation and waste water treatment. Many clinical studies prove the effectiveness of cold plasma in dermatological disease management. Recent researches have established that combined use of cold plasma and nano-formulations is helpful in delivery of poorly water-soluble drugs. Plaque psoriasis is an autoimmune disorder in which silvery, thick, dead layer of skin shades off and cause inflammation, sometimes bleeding. It occurs in 3-4 percent of total world population. Scientific studies have proved that nano-scale particles permeate easily and interact with immune cells like lnterleukin-16, cytokines and TNF-alfa during inflammation and autoimmune disorders. As a result of which, thick layer of keratinocytes is produced and formation of TNF-alfa and interleukin is inhibited which are the causes of Plaque psoriasis. Since conventional medication has only been helpful in managing it, researches have been carried out using various techniques like phototherapy, use of UVA, UVB, IPL (Intense Pulsed Light), PDL (Pulsed Dye Light), LASER and low-level LASER light etc. but their excess exposure causes risk of skin cancer. Other therapies like use of nanometric Liposomes, Niosomes and their combination therapy are some novel clinical techniques for combating symptoms but are still in clinical trial. Since, Plasma therapy is non irritating and stops the triggering mechanism of inflammation, hence the use of nanotechnological topical formulation in combination with plasma therapy has the potential to become possible treatment of Plaque Psoriasis in future.

Decay of Skin-Specific Gene Modules in Pangolins

The mammalian skin exhibits a rich spectrum of evolutionary adaptations. The pilosebaceous unit, composed of the hair shaft, follicle, and the sebaceous gland, is the most striking synapomorphy. The evolutionary diversification of mammals across different ecological niches was paralleled by the appearance of an ample variety of skin modifications. Pangolins, order Pholidota, exhibit keratin-derived scales, one of the most iconic skin appendages. This formidable armor is intended to serve as a deterrent against predators. Surprisingly, while pangolins have hair on their abdomens, the occurrence of sebaceous and sweat glands is contentious. Here, we explore various molecular modules of skin physiology in four pangolin genomes, including that of sebum production. We show that genes driving wax monoester formation, Awat1/2, show patterns of inactivation in the stem pangolin branch, while the triacylglycerol synthesis gene Dgat2l6 seems independently eroded in the African and Asian clades. In contrast, Elovl3 implicated in the formation of specific neutral lipids required for skin barrier function is intact and expressed in the pangolin skin. An extended comparative analysis shows that genes involved in skin pathogen defense and structural integrity of keratinocyte layers also show inactivating mutations: associated with both ancestral and independent pseudogenization events. Finally, we deduce that the suggested absence of sweat glands is not paralleled by the inactivation of the ATP-binding cassette transporter Abcc11, as previously described in Cetacea. Our findings reveal the sophisticated and complex history of gene retention and loss as key mechanisms in the evolution of the highly modified mammalian skin phenotypes.

Three-Dimensional Artificial Skin Construct Bioprinted with a Marine-Based Biocomposite.

A variety of artificial skin scaffolds, including 3D-bioprinted constructs, have been widely studied for regenerating injured skin tissue. Here, we devised a new composite biomaterial ink using fish-skin-based decellularized extracellular matrices (dECM) from tilapia and cod fish. The composition of the biocomposite mixture was carefully selected to obtain a mechanically stable and highly bioactive artificial cell construct. In addition, the decellularized extracellular matrices were methacrylated, followed by exposure to UV light to initiate photo-cross-linking. Porcine-skin-based dECMMa (pdECMMa) and tilapia-skin-based dECMMa (tdECMMa) biomaterials were used as controls. Assessment of various biophysical parameters and in vitro cellular activities, including cytotoxicity, wound healing ability, and angiogenesis, showed that the biocomposite exhibited much higher cellular activities compared to the controls owing to the synergistic effect of the favorable biophysical properties of tdECMMa and bioactive components (collagen, glycosaminoglycans (GAGs), elastin, and free fatty acids) from the decellularized cod skin. Furthermore, the skin constructs bioprinted using the bioinks exhibited more than 90% cell viability, performed with 3 days of submerged culture and then 28 days of air-liquid culture. For all cell constructs, the expression of cytokeratin 10 (CK10) was observed on the top surface of the epidermal layer, and cytokeratin 14 (CK14) was detected in the lower section of the keratinocyte layer. However, more developed CK10 and CK14 antibodies were observed in the cell-laden biocomposite construct [tilapia-skin-based dECMMa with cod-skin-based dECM] than in the controls [porcine-skin-based dECMMa (pdECMMa) and tilapia-skin-based dECMMa (tdECMMa)]. Based on these results, we believe that the fish-skin-based biocomposite construct is a potential biomaterial ink for skin regeneration.