Autophagy: Guardian of Skin Barrier

G Protein-Coupled Receptors in Skin Aging

Skin aging is a complex biological process affected by a plethora of intrinsic and extrinsic factors that alter cutaneous functions through the modulations of signaling pathways and responses. Expressed in various cell types and skin tissue layers, G protein-coupled receptors (GPCRs) play a vital role in regulating skin aging. We have cataloged 156 GPCRs expressed in the skin and reviewed their roles in skin aging, such as pigmentation, loss of elasticity, wrinkles, rough texture, and aging-associated skin disorders. By exploring the GPCRs found in the skin, it may be possible to develop new treatment regimens for aging-associated skin conditions using GPCR ligands.

Understanding the Intricate Pathophysiology of Psoriasis and Related Skin Disorders

Psoriasis is a chronic inflammatory condition that is polygenic and multisystemic, impacting approximately 2-3% of the global population. The onset of this disease is influenced by an intricate interplay of genetic and environmental factors, predisposing individuals to the psoriasis phenotype. The complex pathogenesis of psoriasis contains certain key aspects found in other autoinflammatory and autoimmune dermatological diseases. Among these, vitiligo, alopecia areata, hidradenitis suppurativa, vitiligo, connective tissue diseases, bullous dermatoses, and atopic dermatitis are conditions that share overlapping immune system dysfunction, making their relationship with psoriasis particularly significant. For our research, we explored various terms including "shared", "concomitant", "coincident", "overlap", "coexist", and "concurrent", in relation to conditions such as "psoriasis", "alopecia areata", "hidradenitis suppurativa", "atopic dermatitis", "vitiligo", "bullous pemphigoid", "pemphigus vulgaris", "lupus erythematosus", "dermatomyositis", and "systemic sclerosis." Additionally, we used specific search queries like "atopic dermatitis overlapping syndrome" and "psoriasis and vitiligo concomitant disease" in the PubMed and Web of Science databases. While distinct in their clinical presentation, the skin diseases related to psoriasis may become associated, complicating diagnosis and treatment. In this narrative review, the complex pathophysiology of psoriasis is described, along with its close relationship to other skin conditions. This review provides an exhaustive description of both immunological and non-immunological pathways contributing to their development. Understanding the intricate interconnection between psoriasis and these conditions is of interest to scientists in developing novel research directions and to clinicians in providing holistic care, as managing one condition may influence the course of others.

Chronic Pruritus Alleviation in the Elderly Through Drug-Free Autophagy Activation by Magnetized Saline Water: A Case Series

Chronic pruritus is a common and distressing condition in the elderly population, frequently associated with various underlying systemic diseases and age-related skin changes. Conventional treatments, such as emollients and moisturizers, may not invariably provide adequate relief. Magnetized saline water has previously been shown to activate autophagy, a cellular process involved in maintaining skin barrier function, reducing inflammaging, and modulating neuropathic pain. This case series investigated the efficacy of a topical serum containing magnetized saline water in managing chronic pruritus with diverse etiologies in elderly patients. Five patients aged 69-80 years, presenting with chronic pruritus lasting two to six months, were instructed to apply the serum daily to the most affected areas for a minimum of 14 consecutive days. Pruritus severity was assessed using the 12-Item Pruritus Severity Scale (12-PSS) at baseline and post-intervention. The underlying causes of pruritus included end-stage renal disease, type 2 diabetes mellitus with peripheral neuropathy, advanced liver fibrosis, and xerosis cutis. All five patients reported a substantial improvement in pruritus severity following the application of the magnetized saline water serum, with post-intervention 12-PSS scores decreasing by 3-5 points. The serum was well-tolerated, and no adverse effects were reported. These findings suggest that topical formulations containing magnetized saline water may be a promising alternative or adjunctive therapy for managing chronic pruritus in the elderly population. However, clinical trials are needed to confirm these findings, elucidate the precise mechanisms of action, and establish optimal treatment protocols.

Autophagy Dysfunction: The Kernel of Hair Loss?

Autophagy is recognized as a crucial regulatory process, instrumental in the removal of senescent, dysfunctional, and damaged cells. Within the autophagic process, lysosomal digestion plays a critical role in the elimination of impaired organelles, thus preserving fundamental cellular metabolic functions and various biological processes. Mitophagy, a targeted autophagic process that specifically focuses on mitochondria, is essential for sustaining cellular health and energy balance. Therefore, a deep comprehension of the operational mechanisms and implications of autophagy and mitophagy is vital for disease prevention and treatment. In this context, we examine the role of autophagy and mitophagy during hair follicle cycles, closely scrutinizing their potential association with hair loss. We also conduct a thorough review of the regulatory mechanisms behind autophagy and mitophagy, highlighting their interaction with hair follicle stem cells and dermal papilla cells. In conclusion, we investigate the potential of manipulating autophagy and mitophagy pathways to develop innovative therapeutic strategies for hair loss.

The multifaceted role of autophagy in skin autoimmune disorders: a guardian or culprit?

Autophagy is a cellular process that functions to maintain intracellular homeostasis via the degradation and recycling of defective organelles or damaged proteins. This dynamic mechanism participates in various biological processes, such as the regulation of cellular differentiation, proliferation, survival, and the modulation of inflammation and immune responses. Recent evidence has demonstrated the involvement of polymorphisms in autophagy-related genes in various skin autoimmune diseases. In addition, autophagy, along with autophagy-related proteins, also contributes to homeostasis maintenance and immune regulation in the skin, which is associated with skin autoimmune disorders. This review aims to provide an overview of the multifaceted role of autophagy in skin autoimmune diseases and shed light on the potential of autophagy-targeting therapeutic strategies in dermatology.

The role of epithelial cells in fibrosis: Mechanisms and treatment

Fibrosis is a pathological process that affects multiple organs and is considered one of the major causes of morbidity and mortality in multiple diseases, resulting in an enormous disease burden. Current studies have focused on fibroblasts and myofibroblasts, which directly lead to imbalance in generation and degradation of extracellular matrix (ECM). In recent years, an increasing number of studies have focused on the role of epithelial cells in fibrosis. In some cases, epithelial cells are first exposed to external physicochemical stimuli that may directly drive collagen accumulation in the mesenchyme. In other cases, the source of stimulation is mainly immune cells and some cytokines, and epithelial cells are similarly altered in the process. In this review, we will focus on the multiple dynamic alterations involved in epithelial cells after injury and during fibrogenesis, discuss the association among them, and summarize some therapies targeting changed epithelial cells. Especially, epithelial mesenchymal transition (EMT) is the key central step, which is closely linked to other biological behaviors. Meanwhile, we think studies on disruption of epithelial barrier, epithelial cell death and altered basal stem cell populations and stemness in fibrosis are not appreciated. We believe that therapies targeted epithelial cells can prevent the progress of fibrosis, but not reverse it. The epithelial cell targeting therapies will provide a wonderful preventive and delaying action.

Melatonin inhibits fibroblast cell functions and hypertrophic scar formation by enhancing autophagy through the MT2 receptor-inhibited PI3K/Akt /mTOR signaling

Hypertrophic scar (HS) is a fibrotic skin condition and characterized by abnormal proliferation of myofibroblasts and accumulation of extracellular matrix. Melatonin, an endogenous hormone, can alleviate fibrosis in multiple models of diseases. This study examined the effect of melatonin on fibrosis in primary fibroblasts from human HS (HSFs) and a rabbit ear model and potential mechanisms. Melatonin treatment significantly decreased the migration and contraction capacity, collagen and α-smooth muscle actin (α-SMA) production in HSFs. RNA-sequencing and bioinformatic analyses indicated that melatonin modulated the expression of genes involved in autophagy and oxidative stress. Mechanistically, melatonin treatment attenuated the AKT/mTOR activation through affecting the binding of MT2 receptor with PI3K to enhance autophagy, decreasing fibrogenic factor production in HSFs. Moreover, melatonin treatment inhibited HS formation in rabbit ears by enhancing autophagy. The anti-fibrotic effects of melatonin were abrogated by treatment with an autophagy inhibitor (3-methyladenine, 3-MA), an Akt activator (SC79), or an MT2 selective antagonist (4-phenyl-2propionamidotetralin, 4-P-PDOT). Therefore, melatonin may be a potential drug for prevention and treatment of HS.

Palmatine treats urticaria by reducing inflammation and increasing autophagy

Introduction

Chronic spontaneous urticaria (CSU) is mainly manifested as wheals and erythema on the skin accompanied by itching, which will cause emotional anxiety and seriously affect the quality of life in patients. Palmatine (PAL) is a main chemical component of Yajieshaba, which has been found to effectively alleviate the symptoms of food allergy. However, its role and mechanism in CSU remain unclear. The present study aimed to investigate the protective effect of PAL on CSU rats.

Methods

We replicated the CSU rat model by intraperitoneal injection of ovalbumin (OVA) in rats on days 0, 2, 4, and 14, with a double dose given on the last challenge. PAL, loratadine and saline were given by gavage from day 5 to day 14. We observed the skin pathologic changes, mast cell degranulation, immune factor levels, inflammatory response and autophagy-related protein expression in CSU rats.

Results

We found PAL treatment to be effective in alleviating CSU-like skin lesions and reducing itching and mast cell degranulation in rats. Compared with the OVA group, the levels of immune and inflammatory factors were significantly reduced, neutrophil recruitment was alleviated, suggesting a reduced inflammatory response. The autophagy results showed that PAL further increased the expression of LC3, Beclin-1 and p-LKB1, p-AMPK, Atg5, Atg12 and Atg5-Atg12, while P62 and p-p70S6K1 expression decreased. They collectively suggested that autophagic flux was activated after PAL treatment. However, there was an increase in the expression of LC3I, probably due to the fact that PAL induced its accumulation in order to provide substrate for the generation of more LC3II.

Discussion

Overall, PAL had a protective effect on CSU in normal rats, activated the expression of autophagy and improved the inflammatory response.

Phenol-Soluble Modulin α3 Stimulates Autophagy in HaCaT Keratinocytes

BACKGROUND

Phenol-soluble modulins (PSMs) are pore-forming toxins (PFTs) produced by staphylococci. PSMs exert diverse cellular effects, including lytic, pro-apoptotic, pro-inflammatory and antimicrobial actions. Since the effects of PSMs on autophagy have not yet been reported, we evaluated the autophagic activity in HaCaT keratinocytes treated with recombinant PSMα3.

METHODS

The autophagic flux and levels of autophagic marker proteins were determined using Western blot analysis. Subcellular localization of LC3B and Beclin-1 was investigated using an indirect immunofluorescence assay. The ultrastructural features of control and PSMα3-treated cells were evaluated via transmission electron microscopy. Cytoplasmic acidification was measured via acridine orange staining. Phosphorylation levels of protein kinases, implicated in autophagy regulation, were studied using a phospho-kinase array and Western blot analysis.

RESULTS

PSMα3 facilitated the intracellular redistribution of LC3B, increased the average number of autophagosomes per cell, promoted the development of acidic vesicular organelles, elevated the levels of LC3B-II, stimulated autophagic flux and triggered a significant decrease in the net autophagic turnover rate. PSMα3 induced the accumulation of autophagosomes/autolysosomes, amphisomes and multilamellar bodies at the 0.5, 6 and 24 h time points, respectively. The phospho-Akt1/2/3 (T308 and S473), and phospho-mTOR (S2448) levels were decreased, whereas the phospho-Erk1/2 (T202/Y204 and T185/Y187) level was increased in PSMα3-treated cells.

CONCLUSIONS

In HaCaT keratinocytes, PSMα3 stimulates autophagy. The increased autophagic activity elicited by sub-lytic PSM concentrations might be an integral part of the cellular defense mechanisms protecting skin homeostasis.

Phytochemicals: Targeting autophagy to treat psoriasis

BACKGROUND

Psoriasis is an immune-mediated chronic inflammatory skin disease characterized by well-defined erythema and white scales, which affects approximately 2% of the worldwide population and causes long-term distress to patients. Therefore, development of safe and effective therapeutic drugs is imminent. Autophagy, an evolutionarily conserved catabolic process, degrades intracellular constituents to maintain cellular energy homeostasis. Numerous studies have revealed that autophagy is closely related to immune function, such as removal of intracellular bacteria, inflammatory cytokine secretion, antigen presentation, and lymphocyte development. Phytochemicals derived from natural plants are often used to treat psoriasis due to their unique therapeutic properties and favorable safety. So far, a mass of phytochemicals have been proven to be able to activate autophagy and thus alleviate psoriasis. This review aimed to provide directions for finding phytochemicals that target autophagy to treat psoriasis.

METHODS

The relevant literatures were collected from classical TCM books and a variety of databases (PubMed, Google Scholar, ScienceDirect, Springer Link, Web of Science and China National Knowledge Infrastructure) till December 2022. Search terms were "Phytochemical", "Psoriasis" and "Autophagy". The retrieved data followed PRISMA criteria (preferred reporting items for systematic review).

RESULTS

Phytochemicals treat psoriasis mainly through regulating immune cell function, inhibiting excessive inflammatory response, and reducing oxidative stress. While the role and mechanism of autophagy in the pathogenesis of psoriasis have been confirmed in human trials, most of the evidence for phytochemicals that target autophagy to treat psoriasis comes from animal studies. The research focusing on the role of phytochemical-mediated autophagy in the prevention and treatment of psoriasis is limited, and the definite relationship between phytochemical-regulated autophagy and treatment of psoriasis still deserves further experimental confirmation.

CONCLUSIONS

Phytochemicals with autophagic activities will provide new insights into the therapeutic intervention for psoriasis.

Topically Applied Magnetized Saline Water Improves Skin Biophysical Parameters Through Autophagy Activation: A Pilot Study

Background Water exposed to a magnetic field exhibits several changes in its properties, such as increased electrical conductivity, reduced density, and low surface tension. Additionally, it has reduced dissolved oxygen levels and becomes more alkaline. Previous experimental studies have demonstrated that exposure to saline alkaline water leads to a dose-dependent increase in the expression of autophagy-related genes. Here, we hypothesize that the topical application of magnetized alkaline water to the skin can activate autophagy and improve cutaneous biophysical parameters, making it a promising strategy for enhancing skin aesthetics. Methods Two distinct substudies were undertaken. Firstly, a 12-week, uncontrolled, open-label investigation was conducted with 20 females who desired to enhance the appearance of their facial and neck skin. Secondly, a molecular study was carried out on a subset of 10 females to investigate the serum's impact on two autophagy markers (Beclin-1 and mammalian/mechanistic target of rapamycin {mTOR}) in skin biopsies taken from the posterior neck area below the hair attachment line. Results After a period of 12 weeks, the application of the serum resulted in significant improvements in skin hydration within the stratum corneum (56 ± 14 arbitrary units {a.u.}) compared to the baseline measurement (47 ± 12 a.u.; p < 0.001). Moreover, the transepidermal water loss (TEWL) decreased from 14 ± 2 g/m2/hour to 11 ± 3 g/m2/hour (p < 0.001). The results also revealed a notable reduction in sebum content from 38 ± 7 µg/cm2 to 30 ± 4 µg/cm2 after the 12-week period of serum application (<0.001). Additionally, the melanin index (p < 0.01) and erythema index (p < 0.001) were both significantly lower at 12 weeks compared to baseline. The molecular study showed a 38% increase in Beclin-1 levels after 12 weeks of serum application on the posterior neck area, as measured from skin biopsies. In contrast, mTOR levels decreased by 24% from baseline to 12 weeks. Conclusion The application of magnetized saline water topically, within a serum formulation, shows potential in improving skin biophysical parameters for females seeking to enhance the appearance of their facial and neck skin. These beneficial effects are achieved through the activation of cutaneous autophagy, as evidenced by an increase in Beclin-1 expression and a decrease in mTOR content in the skin.

Deciphering the single-cell transcriptome network in keloids with intra-lesional injection of triamcinolone acetonide combined with 5-fluorouracil

Objectives

Keloid is a highly aggressive fibrotic disease resulting from excessive extracellular matrix deposition after dermal injury. Intra-lesional injection of triamcinolone acetonide (TAC) in combination with 5-fluorouracil (5-FU) is a commonly used pharmacological regimen and long-term repeated injections can achieve sustained inhibition of keloid proliferation. However, the molecular mechanisms underlying the inhibitory effect on keloids remain insufficiently investigated.

Methods and materials

This study performed single-cell RNA sequencing analysis of keloids treated with TAC+5-FU injections, keloids, and skins to explore patterns of gene expression regulation and cellular reprogramming.

Results

The results revealed that TAC+5-FU interrupted the differentiation trajectory of fibroblasts toward pro-fibrotic subtypes and induced keloid atrophy possibly by inhibiting the FGF signaling pathway in intercellular communication. It also stimulated partial fibroblasts to develop the potential for self-replication and multidirectional differentiation, which may be a possible cellular source of keloid recurrence. T cell dynamics demonstrated elevated expression of secretory globulin family members, which may be possible immunotherapeutic targets. Schwann cell populations achieved functional changes by increasing the proportion of apoptotic or senescence-associated cell populations and reducing cell clusters that promote epidermal development and fibroblast proliferation.

Conclusions

Our findings elucidated the molecular and cellular reprogramming of keloids by intra-lesional injection of TAC+5-FU, which will provide new insights to understand the mechanism of action and therapeutic targets.

The Role of Oxidative Stress in Vitiligo: An Update on Its Pathogenesis and Therapeutic Implications

Vitiligo is an autoimmune skin disorder caused by dysfunctional pigment-producing melanocytes which are attacked by immune cells. Oxidative stress is considered to play a crucial role in activating consequent autoimmune responses related to vitiligo. Melanin synthesis by melanocytes is the main intracellular stressor, producing reactive oxygen species (ROS). Under normal physiological conditions, the antioxidative nuclear factor erythroid 2-related factor 2 (Nrf2) pathway functions as a crucial mediator for cells to resist oxidative stress. In pathological situations, such as with antioxidant defects or under inflammation, ROS accumulate and cause cell damage. Herein, we summarize events at the cellular level under excessive ROS in vitiligo and highlight exposure to melanocyte-specific antigens that trigger immune responses. Such responses lead to functional impairment and the death of melanocytes, which sequentially increase melanocyte cytotoxicity through both innate and adaptive immunity. This report provides new perspectives and advances our understanding of interrelationships between oxidative stress and autoimmunity in the pathogenesis of vitiligo. We describe progress with targeted antioxidant therapy, with the aim of providing potential therapeutic approaches.

Alopecia Areata: A Review of the Role of Oxidative Stress, Possible Biomarkers, and Potential Novel Therapeutic Approaches

Alopecia areata (AA) is a dermatological condition characterized by non-scarring hair loss. Exact etiopathogenesis of AA is still unknown although it is known that several factors contribute to the collapse of the hair-follicle (HF)-immune-privileged (IP) site. Oxidative stress (OS) plays an important role in skin diseases. The aim of this review was to clarify the role of OS in AA pathogenesis and diagnosis, and to discuss potential treatment options. Oxidative-stress markers are altered in serum and skin samples of patients with AA, confirming a general pro-oxidative status in patients with AA. OS induces MHC class I chain-related A (MICA) expression in HF keratinocytes that activates the receptor NKG2D, expressed in NK cells and CD8+ T cytotoxic cells leading to destabilization of the HF immune-privileged site through the production of IFN-γ that stimulates JAK1 and JAK2 pathways. OS also activates the KEAP1-NRF2 pathway, an antioxidant system that contributes to skin homeostasis. In addition, a decrease of ATG5 and LC3B in the hair matrix and an increase in p62 levels indicates a reduction of intrafollicular autophagy during the evolution of AA. Potential biomarkers of OS in AA could be: malondialdehyde (MDA), advanced glycation end-products (AGEs), and ischemic-modified albumin (IMA). JAK inhibitors are the new frontier in treatment of AA and the use of nutraceuticals that modulate the OS balance, in combination with standard treatments, represent promising therapeutic tools.

Deciphering the Function of New Therapeutic Targets and Prospective Biomarkers in the Management of Psoriasis

Psoriasis is an immune-mediated skin condition affecting people worldwide, presenting at any age, and leading to a substantial burden physically and mentally. The innate and adaptive immune systems interact intricately with the pathomechanisms that underlie disease. T cells can interact with keratinocytes, macrophages, and dendritic cells through the cytokines they secrete. According to recent research, psoriasis flare-ups can cause systemic inflammation and various other co-morbidities, including depression, psoriatic arthritis, and cardio-metabolic syndrome. Additionally, several auto-inflammatory and auto-immune illnesses may be linked to psoriasis. Although psoriasis has no proven treatment, care must strive by treating patients as soon as the disease surfaces, finding and preventing concurrent multimorbidity, recognising and reducing bodily and psychological distress, requiring behavioural modifications, and treating each patient individually. Biomarkers are traits that are assessed at any time along the clinical continuum, from the early stages of a disease through the beginning of treatment (the foundation of precision medicine) to the late stages of treatment (outcomes and endpoints). Systemic therapies that are frequently used to treat psoriasis provide a variety of outcomes. Targeted therapy selection, better patient outcomes, and more cost-effective healthcare would be made possible by biomarkers that reliably predict effectiveness and safety. This review is an attempt to understand the role of Antimicrobial peptides (AMP), Interleukin-38 (IL-38), autophagy 5 (ATG5) protein and squamous cell carcinoma antigen (SCCA) as biomarkers of psoriasis.