TLR4-mediated activation of the ERK pathway following UVA irradiation contributes to increased cytokine and MMP expression in senescent human dermal fibroblasts

Exosomes in skin photoaging: biological functions and therapeutic opportunity

Exosomes are tiny extracellular vesicles secreted by most cell types, which are filled with proteins, lipids, and nucleic acids (non-coding RNAs, mRNA, DNA), can be released by donor cells to subsequently modulate the function of recipient cells. Skin photoaging is the premature aging of the skin structures over time due to repeated exposure to ultraviolet (UV) which is evidenced by dyspigmentation, telangiectasias, roughness, rhytides, elastosis, and precancerous changes. Exosomes are associated with aging-related processes including, oxidative stress, inflammation, and senescence. Anti-aging features of exosomes have been implicated in various in vitro and pre-clinical studies. Stem cell-derived exosomes can restore skin physiological function and regenerate or rejuvenate damaged skin tissue through various mechanisms such as decreased expression of matrix metalloproteinase (MMP), increased collagen and elastin production, and modulation of intracellular signaling pathways as well as, intercellular communication. All these evidences are promising for the therapeutic potential of exosomes in skin photoaging. This review aims to investigate the molecular mechanisms and the effects of exosomes in photoaging.

Urothelial Oxidative Stress and ERK Activation Mediate HMGB1-Induced Bladder Pain

Activation of intravesical protease activated receptors-4 (PAR4) results in bladder pain through the release of urothelial macrophage migration inhibitory factor (MIF) and high mobility group box-1 (HMGB1). We aimed to identify HMGB1 downstream signaling events at the bladder that mediate HMGB1-induced bladder pain in MIF-deficient mice to exclude any MIF-related effects. We studied whether oxidative stress and ERK activation are involved by examining bladder tissue in mice treated with intravesical disulfide HMGB1 for 1 h and analyzed with Western blot and immunohistochemistry. HMGB1 intravesical treatment increased urothelium 4HNE and phospho-ERK1/2 staining, suggesting that HMGB1 increased urothelial oxidative stress and ERK activation. Furthermore, we examined the functional roles of these events. We evaluated lower abdominal mechanical thresholds (an index of bladder pain) before and 24 h after intravesical PAR4 or disulfide HMGB1. Intravesical pre-treatments (10 min prior) included: N-acetylcysteine amide (NACA, reactive oxygen species scavenger) and FR180204 (FR, selective ERK1/2 inhibitor). Awake micturition parameters (voided volume; frequency) were assessed at 24 h after treatment. Bladders were collected for histology at the end of the experiment. Pre-treatment with NACA or FR significantly prevented HMGB1-induced bladder pain. No significant effects were noted on micturition volume, frequency, inflammation, or edema. Thus, HMGB1 activates downstream urothelial oxidative stress production and ERK1/2 activation to mediate bladder pain. Further dissection of HMGB1 downstream signaling pathway may lead to novel potential therapeutic strategies to treat bladder pain.

Blocking the Hormone Receptors Modulates NLRP3 in LPS-Primed Breast Cancer Cells

NOD-like receptor protein 3 (NLRP3) may contribute to the growth and propagation of breast cancer (BC). The effect of estrogen receptor-α (ER-α), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) on NLRP3 activation in BC remains unknown. Additionally, our knowledge of the effect of blocking these receptors on NLRP3 expression is limited. We used GEPIA, UALCAN, and the Human Protein Atlas for transcriptomic profiling of NLRP3 in BC. Lipopolysaccharide (LPS) and adenosine 5'-triphosphate (ATP) were used to activate NLRP3 in luminal A MCF-7 and in TNBC MDA-MB-231 and HCC1806 cells. Tamoxifen (Tx), mifepristone (mife), and trastuzumab (Tmab) were used to block ER-α, PR, and HER2, respectively, on inflammasome activation in LPS-primed MCF7 cells. The transcript level of NLRP3 was correlated with ER-ɑ encoding gene ESR1 in luminal A (ER-α⁺, PR⁺) and TNBC tumors. NLRP3 protein expression was higher in untreated and LPS/ATP-treated MDA-MB-231 cells than in MCF7 cells. LPS/ATP-mediated NLRP3 activation reduced cell proliferation and recovery of wound healing in both BC cell lines. LPS/ATP treatment prevented spheroid formation in MDA-MB-231 cells but did not affect MCF7. HGF, IL-3, IL-8, M-CSF, MCP-1, and SCGF-b cytokines were secreted in both MDA-MB-231 and MCF7 cells in response to LPS/ATP treatment. Tx (ER-α inhibition) promoted NLRP3 activation and increased migration and sphere formation after LPS treatment of MCF7 cells. Tx-mediated activation of NLRP3 was associated with increased secretion of IL-8 and SCGF-b compared to LPS-only-treated MCF7 cells. In contrast, Tmab (Her2 inhibition) had a limited effect on NLRP3 activation in LPS-treated MCF7 cells. Mife (PR inhibition) opposed NLRP3 activation in LPS-primed MCF7 cells. We have found that Tx increased the expression of NLRP3 in LPS-primed MCF7. These data suggest a link between blocking ER-α and activation of NLRP3, which was associated with increased aggressiveness of the ER-α⁺ BC cells.

The role of cytokines/chemokines in an aging skin immune microenvironment

Reversing or slowing down the skin aging process is one of the most intriguing areas of focus across the social and scientific communities around the world. While aging is considered a universal and inevitable natural process of physiological decline, the aging of the skin is the most apparent visual representation of an individual's health. Aging skin may be objectively defined by epidermal thinning; increased transepidermal water loss; decreased cutaneous barrier function; loss of elasticity, laxity, and textured appearance; and gradual deterioration of the epidermal immune environment. As the largest structure of the immune system and of the body as a whole, the skin is the most vulnerable barrier of defense against the environment. The skin reflects an individual's exposures, lifestyle habits, and overall health. From an immunological perspective, cytokines and chemokines act as a central character in the communicating of the immunity in skin aging. These cell signaling proteins serve as the intercellular communication link. This review aims to elucidate how cell-cell crosstalk through cytokines and chemokines, and the interplay between host cells, infiltrating immune cells, and exogenous factors contribute to the overall aging skin.

(-)-Epigallocatechin-3-Gallate Protects Human Skin Fibroblasts from Ultraviolet a Induced Photoaging

Background

Ultraviolet (UV) is a common stressor of skin and repeated UVA radiation contributes to photoaging. (-)-Epigallocatechin-3-Gallate (EGCG), as the major polyphenol that is found in green tea, and catechins and have shown considerable antioxidant capacity.

Purpose

Our study aims to explore the effects of EGCG on UVA-induced skin photoaging process and associated mechanisms.

Methods

In this study, human skin fibroblasts (HSFs) were treated with UVA and EGCG, and subsequent changes in cell morphology, telomeres, antioxidant capacity, cell cycle, and related genes were evaluated to examine the role and mechanisms of EGCG in delaying skin photoaging.

Results

HSF exposed to UVA underwent an increase in aging-related biomarkers and telomere shortening. Also, UVA radiation inhibited the secretion of transforming growth factor-beta1 (TGF-β1), induced cell cycle arrest, down-regulated antioxidant enzymes, and promoted the accumulation of oxidative product malondialdehyde (MDA) to cause further damage to cells. Increased expression of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinase-1 (TIMP-1), p66 at mRNA levels were also observed after UVA irradiation. EGCG treatment effectively inhibited above damage processes caused by UVA radiation in HSF.

Conclusion

Our study indicated that the potential mechanism of EGCG retarding photoaging is closely related to its powerful antioxidant effects and the ability to regulate the expression of related genes, and the usage of EGCG will be a potential strategy in preventing skin photoaging induced by UVA radiation.

Old plasma dilution reduces human biological age: a clinical study

This work extrapolates to humans the previous animal studies on blood heterochronicity and establishes a novel direct measurement of biological age. Our results support the hypothesis that, similar to mice, human aging is driven by age-imposed systemic molecular excess, the attenuation of which reverses biological age, defined in our work as a deregulation (noise) of 10 novel protein biomarkers. The results on biological age are strongly supported by the data, which demonstrates that rounds of therapeutic plasma exchange (TPE) promote a global shift to a younger systemic proteome, including youthfully restored pro-regenerative, anticancer, and apoptotic regulators and a youthful profile of myeloid/lymphoid markers in circulating cells, which have reduced cellular senescence and lower DNA damage. Mechanistically, the circulatory regulators of the JAK-STAT, MAPK, TGF-beta, NF-κB, and Toll-like receptor signaling pathways become more youthfully balanced through normalization of TLR4, which we define as a nodal point of this molecular rejuvenation. The significance of our findings is confirmed through big-data gene expression studies.

Mitochondrial transfer/transplantation: an emerging therapeutic approach for multiple diseases

Mitochondria play a pivotal role in energy generation and cellular physiological processes. These organelles are highly dynamic, constantly changing their morphology, cellular location, and distribution in response to cellular stress. In recent years, the phenomenon of mitochondrial transfer has attracted significant attention and interest from biologists and medical investigators. Intercellular mitochondrial transfer occurs in different ways, including tunnelling nanotubes (TNTs), extracellular vesicles (EVs), and gap junction channels (GJCs). According to research on intercellular mitochondrial transfer in physiological and pathological environments, mitochondrial transfer hold great potential for maintaining body homeostasis and regulating pathological processes. Multiple research groups have developed artificial mitochondrial transfer/transplantation (AMT/T) methods that transfer healthy mitochondria into damaged cells and recover cellular function. This paper reviews intercellular spontaneous mitochondrial transfer modes, mechanisms, and the latest methods of AMT/T. Furthermore, potential application value and mechanism of AMT/T in disease treatment are also discussed.

Asterias pectinifera-Derived Collagen Peptides Mixed with Halocynthia roretzi Extracts Exhibit Anti-Photoaging Activities during Exposure to UV Irradiation, and Antibacterial Properties

Asterias pectinifera, a species of starfish and cause of concern in the aquaculture industry, was recently identified as a source of non-toxic and highly water-soluble collagen peptides. In this study, we investigated the antioxidant and anti-photoaging functions of compounds formulated using collagen peptides from extracts of Asterias pectinifera and Halocynthia roretzi (AH). Our results showed that AH compounds have various skin protective functions, including antioxidant effects, determined by measuring the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl radicals, as well as anti-melanogenic effects, determined by measuring tyrosinase inhibition activity. To determine whether ethosome-encapsulated AH compounds (E(AH)) exert ultraviolet (UV)-protective effects, human dermal fibroblasts or keratinocytes were incubated with E(AH) before and after exposure to UVA or UVB. E(AH) treatment led to inhibition of photoaging-induced secretion of matrix metalloproteinase-1 and interleukin-6 and -8, which are associated with inflammatory responses during UV irradiation. Finally, the antibacterial effects of AH and E(AH) were confirmed against both gram-negative and gram-positive bacteria. Our results indicate that E(AH) has the potential for use in the development of cosmetics with a range of skin protective functions.

Chronic infrared-A irradiation-induced photoaging of human dermal fibroblasts from different donors at physiological temperature

BACKGROUND

In this study, we examined cellular responses to acute and chronic IRA irradiation at mild and natural levels of exposure in two types of human fibroblasts, each isolated from a different donor, at physiological temperature (34°C).

METHOD

Two types of human dermal fibroblasts (derived from a 20- and 50-year-old women, respectively) were exposed to different repeat numbers of IRA exposure (3, 6, 10, and 14 times; 42 mW/cm² ) at a frequency of 3-4 times per week (4 h per irradiation). Cellular responses to acute and chronic IRA irradiation were examined by reactive oxygen species (ROS) level, apoptotic signals, cellular morphology, and collagen level.

RESULTS

We demonstrated that chronic IRA irradiation-induced severe cellular damage, including prolonged cell proliferation, increased intracellular ROS levels, activated cellular apoptosis, and elongated cell morphology, whereas acute IRA irradiation had negligible effects at 34°C. In addition, it was evident that the degree of cellular damage due to IRA irradiation differed according to the type of fibroblasts.

CONCLUSIONS

Considering the severe cellular damage induced by chronic IRA irradiation without heat, continuous exposure of skin to IRA irradiation during daily life may be harmful enough to induce photoaging.

Role of mitochondria on UV-induced skin damage and molecular mechanisms of active chemical compounds targeting mitochondria

Mitochondria are the principal place of energy metabolism and ROS production, leading to mtDNA being especially sensitive to the impacts of oxidative stress. Our review aims to elucidate and update the mechanisms of mitochondria in UV-induced skin damage. The mitochondrial deteriorative response to UV manifests morphological and functional alterations, including mitochondrial fusion and fission, mitochondrial biogenesis, mitochondrial energy metabolism and mitophagy. Additionally, we conclude the effect and molecular mechanisms of active chemical components to protect skin from UV-induced damage via mitochondrial protection which have been described in the last five years, showing prospective prospects in cosmetics as new therapeutic targets.

Mitochondria-Targeted Hydrogen Sulfide Delivery Molecules Protect Against UVA-Induced Photoaging in Human Dermal Fibroblasts, and in Mouse Skin In Vivo

Aims: Oxidative stress and mitochondrial dysfunction play a role in the process of skin photoaging via activation of matrix metalloproteases (MMPs) and the subsequent degradation of collagen. The activation of nuclear factor E2-related factor 2 (Nrf2), a transcription factor controlling antioxidant and cytoprotective defense systems, might offer a pharmacological approach to prevent skin photoaging. We therefore investigated a pharmacological approach to prevent skin photoaging, and also investigated a protective effect of the novel mitochondria-targeted hydrogen sulfide (H₂S) delivery molecules AP39 and AP123, and nontargeted control molecules, on ultraviolet A light (UVA)-induced photoaging in normal human dermal fibroblasts (NHDFs) in vitro and the skin of BALB/c mice in vivo. Results: In NHDFs, AP39 and AP123 (50-200 nM) but not nontargeted controls suppressed UVA (8 J/cm²)-mediated cytotoxicity and induction of MMP-1 activity, preserved cellular bioenergetics, and increased the expression of collagen and nuclear levels of Nrf2. In in vivo experiments, topical application of AP39 or AP123 (0.3-1 μM/cm²; but not nontargeted control molecules) to mouse skin before UVA (60 J/cm²) irradiation prevented skin thickening, MMP induction, collagen loss of oxidative stress markers 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased Nrf2-dependent signaling, as well as increased manganese superoxide dismutase levels and levels of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α). Innovation and Conclusion: Targeting H₂S delivery to mitochondria may represent a novel approach for the prevention and treatment of skin photoaging, as well as being useful tools for determining the role of mitochondrial H₂S in skin disorders and aging. Antioxid. Redox Signal. 36, 1268-1288.

miR-10a, miR-30c, and miR-451a encapsulated in small extracellular vesicles are pro-senescence factors in human dermal fibroblasts

Although small extracellular vesicles (sEV) have been reported to play an important role in cellular senescence and aging, little is known about the potential role and function of microRNAs (miRNAs) contained within the sEV. To determine senescence-associated factors secreted from sEV of human dermal fibroblasts (HDF), we isolated and characterized sEV from non-senescent vs. senescent HDF. Small RNA sequencing analysis identified many enriched miRNAs in sEV of senescent HDF, as shown by the upregulation of miR-10a, miR-30c, and miR-451a, and downregulation of miR-128, miR-184, miR-200c, and miR-125a. Overexpression of miR-10a, miR-30c, and miR-451a induced an aging phenotype in HDF, whereas inhibition of these miRNAs reduced senescent-like phenotypes in senescent HDF. Moreover, treatment with sEV or sEV-containing conditioned medium promoted cellular senescence in HDF, whereas sEV depletion abrogated pro-senescence effects of the senescent HDF secretome. Interestingly, pro-senescence sEV miRNAs were found to have an essential role in regulating reactive oxygen species production and mitophagy activation. Taken together, our results revealed miR-10a, miR-30c, and miR-451a as pro-senescence factors that are differentially expressed in sEV of senescent HDF, demonstrating the essential role of sEV miRNAs in the biological processes of aging.

Immune signaling in rosacea

Rosacea is a common chronic skin disease affecting mostly people aged 40 and above, with currently no cure. When it affects the eyelids and periocular skin, it leads to dry eye and potentially corneal damage. Research performed over the last decade shed light into the potential mechanisms leading to skin hypersensitivity and provided promising avenues for development of novel, rational therapeutics aimed at reducing the skin inflammatory state. In this review, we discuss the current knowledge on the mechanisms of rosacea in general and of periocular skin-affecting disease in particular, identify key questions that remain to be answered in future research, and offer a disease model that can explain the key characteristics of this disease, with particular emphasis on a potential positive feedback loop that could explain both the acute and chronic features of rosacea.

Dynamic Aging: Channeled Through Microenvironment

Aging process is a complicated process that involves deteriorated performance at multiple levels from cellular dysfunction to organ degeneration. For many years research has been focused on how aging changes things within cell. However, new findings suggest that microenvironments, circulating factors or inter-tissue communications could also play important roles in the dynamic progression of aging. These out-of-cell mechanisms pass on the signals from the damaged aging cells to other healthy cells or tissues to promote systematic aging phenotypes. This review discusses the mechanisms of how senescence and their secretome, NAD⁺ metabolism or circulating factors change microenvironments to regulate systematic aging, as well as the potential therapeutic strategies based on these findings for anti-aging interventions.

CVB3-Mediated Mitophagy Plays an Important Role in Viral Replication via Abrogation of Interferon Pathways

Coxsackievirus B3 (CVB3) is a common enterovirus that causes systemic inflammatory diseases, such as myocarditis, meningitis, and encephalitis. CVB3 has been demonstrated to subvert host cellular responses via autophagy to support viral replication in neural stem cells. Mitophagy, a specialized form of autophagy, contributes to mitochondrial quality control via degrading damaged mitochondria. Here, we show that CVB3 infection induces mitophagy in human neural progenitor cells, HeLa and H9C2 cardiomyocytes. In particular, CVB3 infection triggers mitochondrial fragmentation, loss of mitochondrial membrane potential, and Parkin/LC3 translocation to the mitochondria. Rapamycin or carbonyl cyanide m-chlorophenyl hydrazone (CCCP) treatment led to increased CVB3 RNA copy number in a dose-dependent manner, suggesting enhanced viral replication via autophagy/mitophagy activation, whereas knockdown of PTEN-induced putative kinase protein 1(PINK1) led to impaired mitophagy and subsequent reduction in viral replication. Furthermore, CCCP treatment inhibits the interaction between mitochondrial antiviral signaling protein (MAVS) and TANK-binding kinase 1(TBK1), thus contributing to the abrogation of type I and III interferon (IFN) production, suggesting that mitophagy is essential for the inhibition of interferon signaling. Our findings suggest that CVB3-mediated mitophagy suppresses IFN pathways by promoting fragmentation and subsequent sequestration of mitochondria by autophagosomes.

mRNA and miRNA profiling of Zika virus-infected human umbilical cord mesenchymal stem cells identifies miR-142-5p as an antiviral factor

Zika virus (ZIKV) infection during pregnancy is associated with congenital brain abnormalities, a finding that highlights the urgent need to understand mother-to-fetus transmission mechanisms. Human umbilical cord mesenchymal stem cells (hUCMSCs) are susceptible to ZIKV infection but the underlying mechanisms of viral susceptibility remain largely unexplored. In this study, we have characterized and compared host mRNA and miRNA expression profiles in hUCMSCs after infection with two lineages of ZIKV, African (MR766) and Asian (PRVABC59). RNA sequencing analysis identified differentially expressed genes involved in anti-viral immunity and mitochondrial dynamics following ZIKV infection. In particular, ZIKV-infected hUCMSCs displayed mitochondrial elongation and the treatment of hUCMSCs with mitochondrial fission inhibitor led to a dose-dependent increase in ZIKV gene expression and decrease in anti-viral signalling pathways. Moreover, small RNA sequencing analysis identified several significantly up- or down-regulated microRNAs. Interestingly, miR-142-5p was significantly downregulated upon ZIKV infection, whereas cellular targets of miR-142-5p, IL6ST and ITGAV, were upregulated. Overexpression of miR-142-5p resulted in the suppression of ZIKV replication. Furthermore, blocking ITGAV expression resulted in a significant suppression of ZIKV binding to cells, suggesting a potential role of ITGAV in ZIKV entry. In conclusion, these results demonstrate both common and specific host responses to African and Asian ZIKV lineages and indicate miR-142-5p as a key regulator of ZIKV replication in the umbilical cords.

RAGE Differentially Altered in vitro Responses in Vascular Smooth Muscle Cells and Adventitial Fibroblasts in Diabetes-Induced Vascular Calcification

The Advanced Glycation End-Products (AGE)/Receptor for AGEs (RAGE) signaling pathway exacerbates diabetes-mediated vascular calcification (VC) in vascular smooth muscle cells (VSMCs). Other cell types are involved in VC, such as adventitial fibroblasts (AFBs). We hope to elucidate some of the mechanisms responsible for differential signaling in diabetes-mediated VC with this work. This work utilizes RAGE knockout animals and in vitro calcification to measure calcification and protein responses. Our calcification data revealed that VSMCs calcification was AGE/RAGE dependent, yet AFBs calcification was not an AGE-mediated RAGE response. Protein expression data showed VSMCs lost their phenotype marker, α-smooth muscle actin, and had a higher RAGE expression over non-diabetics. RAGE knockout (RKO) VSMCs did not show changes in phenotype markers. P38 MAPK, a downstream RAGE-associated signaling molecule, had significantly increased activation with calcification in both diabetic and diabetic RKO VSMCs. AFBs showed a loss in myofibroblast marker, α-SMA, due to calcification treatment. RAGE expression decreased in calcified diabetic AFBs, and P38 MAPK activation significantly increased in diabetic and diabetic RKO AFBs. These findings point to potentially an alternate receptor mediating the calcification response in the absence of RAGE. Overall, VSMCs and AFBs respond differently to calcification and the application of AGEs.

Antioxidant Properties of Plant-Derived Phenolic Compounds and Their Effect on Skin Fibroblast Cells

Plants are rich sources of a diverse range of chemicals, many of which have significant metabolic activity. One large group of secondary compounds are the phenolics, which act as inter alia potent reactive oxygen scavengers in cells, including fibroblasts. These common dermis residue cells play a crucial role in the production of extracellular matrix components, such as collagen, and maintaining the integrity of connective tissue. Chronic wounds or skin exposure to UV-irradiation disrupt fibroblast function by the generation of reactive oxygen species, which may damage cell components and modify various signaling pathways. The resulting imbalance may be reversed by the antioxidant activity of plant-derived phenolic compounds. This paper reviews the current state of knowledge on the impact of phenolics on fibroblast functionality under oxidative stress conditions. It examines a range of compounds in extracts from various species, as well as single specific plant-derived compounds. Phenolics are a good candidate for eliminating the causes of skin damage including wounds and aging and acting as skin care agents.

Ultraviolet radiation, vitamin D, and COVID-19

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has become pandemic on March 11^th, 2020. COVID-19 has a range of symptoms that includes fever, fatigue, dry cough, aches, and labored breathing to acute respiratory distress and possibly death. Health systems and hospitals have been completely rearranged since March 2020 in order to limit the high rate of virus spreading. Hence, a great debate on deferrable visits and treatments including phototherapy for skin diseases is developing. In particular, as regards phototherapy very few data are currently available regarding the chance to continue it, even if it may be a useful resource for treating numerous dermatological patients. However, phototherapy has an immunosuppressive action possibly facilitating virus infection. In the context of COVID-19 infection risk it is important to pointed out whether sunlight, phototherapy and in particular ultraviolet radiation (UV-R) constitute or not a risk for patients. In this review we aimed to focus on the relationship between UV-R, sunlight, phototherapy, and viral infections particularly focusing on COVID-19.

Toll-like receptor 2 induced senescence in intervertebral disc cells of patients with back pain can be attenuated by o-vanillin

BACKGROUND

There is an increased level of senescent cells and toll-like teceptor-1, -2, -4, and -6 (TLR) expression in degenerating intervertebral discs (IVDs) from back pain patients. However, it is currently not known if the increase in expression of TLRs is related to the senescent cells or if it is a more general increase on all cells. It is also not known if TLR activation in IVD cells will induce cell senescence.

METHODS

Cells from non-degenerate human IVD were obtained from spine donors and cells from degenerate IVDs came from patients undergoing surgery for low back pain. Gene expression of TLR-1,2,4,6, senescence and senescence-associated secretory phenotype (SASP) markers was evaluated by RT-qPCR in isolated cells. Matrix synthesis was verified with safranin-O staining and Dimethyl-Methylene Blue Assay (DMMB) confirmed proteoglycan content. Protein expression of p16INK4a, SASP factors, and TLR-2 was evaluated by immunocytochemistry (ICC) and/or by enzyme-linked immunosorbent assay (ELISA).

RESULTS

An increase in senescent cells was found following 48-h induction with a TLR-2/6 agonist in cells from both non-degenerate and degenerating human IVDs. Higher levels of SASP factors, TLR-2 gene expression, and protein expression were found following 48-h induction with TLR-2/6 agonist. Treatment with o-vanillin reduced the number of senescent cells, and increased matrix synthesis in IVD cells from back pain patients. Treatment with o-vanillin after induction with TLR-2/6 agonist reduced gene and protein expression of SASP factors and TLR-2. Co-localized staining of p16INK4a and TLR-2 demonstrated that senescent cells have a high TLR-2 expression.

CONCLUSIONS

Taken together our data demonstrate that activation of TLR-2/6 induce senescence and increase TLR-2 and SASP expression in cells from non-degenerate IVDs of organ donors without degeneration and back pain and in cells from degenerating human IVD of patients with disc degeneration and back pain. The senescent cells showed high TLR-2 expression suggesting a link between TLR activation and cell senescence in human IVD cells. The reduction in senescence, SASP, and TLR-2 expression suggest o-vanillin as a potential disease-modifying drug for patients with disc degeneration and back pain.

Myeloid differentiation factor 88 expression in eyelid specimens of rosacea

Purpose: Rosacea is a common cause of ocular surface disease. Specific immunologic features have been implicated in its pathogenesis, including toll-like receptors, mitogen-associated kinase, and nuclear factor kappa-B. Myeolid differentiation factor 88 (MYD88) has been associated with these elements, suggesting a role for this protein in rosacea. This study was designed to compare the expression of MYD88 in the eyelids of patients with and without this disease.Methods: Western blotting for MYD88 was performed in 14 control patients and 15 patients with rosacea. Bands were quantified and normalized to actin. Immunohistochemical staining for MYD88 was performed in a different cohort of 12 patients with rosacea and 12 controls, and positively-staining cells were counted across five consecutive 40x fields. Statistical analyses compared the differences between the two groups via a dedicated software package.Results: On western blotting, the mean ratios of MYD88 to actin were 13.8 (standard deviation = 14.1) and 44.3 (standard deviation = 39.6) in control and rosacea patients, respectively (p = .002). On immunohistochemistry, the mean numbers of positively-staining cells were 12.1/40x field (standard deviation = 9.61/40x field) and 27.4/40x (standard deviation = 18.7/40x field) in control and rosacea patients, respectively (p = .0438).Conclusions: MYD88 is enriched in eyelid specimens of rosacea. This finding further implicates the innate immune system in the pathogenesis of rosacea, and is consistent with previous reports regarding the role of this protein in ocular surface disease and the previously-implicated cellular features of the disease. Inhibition of MYD88 may be a successful treatment strategy to manage rosacea.

Cellular senescence and tumor promotion: Role of the Unfolded Protein Response

Senescence is a cellular state which can be viewed as a stress response phenotype implicated in various physiological and pathological processes, including cancer. Therefore, it is of fundamental importance to understand why and how a cell acquires and maintains a senescent phenotype. Direct evidence has pointed to the homeostasis of the endoplasmic reticulum whose control appears strikingly affected during senescence. The endoplasmic reticulum is one of the sensing organelles that transduce signals between different pathways in order to adapt a functional proteome upon intrinsic or extrinsic challenges. One of these signaling pathways is the Unfolded Protein Response (UPR), which has been shown to be activated during senescence. Its exact contribution to senescence onset, maintenance, and escape, however, is still poorly understood. In this article, we review the mechanisms through which the UPR contributes to the appearance and maintenance of characteristic senescent features. We also discuss whether the perturbation of the endoplasmic reticulum proteostasis or accumulation of misfolded proteins could be possible causes of senescence, and-as a consequence-to what extent the UPR components could be considered as therapeutic targets allowing for the elimination of senescent cells or altering their secretome to prevent neoplastic transformation.

Rapamycin Protects Skin Fibroblasts From UVA-Induced Photoaging by Inhibition of p53 and Phosphorylated HSP27

Skin aging caused by UV radiation is called photoaging is characterized by skin roughness and dryness accompanied by a significant reduction of dermal collagen. Rapamycin is a macrolide immunosuppressant which has been shown to exhibit “anti-aging” effects in cells and organisms, however, its roles in the skin photoaging remains unclear. Here, we investigate the role of rapamycin and HSP27, which we have previously identified as an inhibitor of UV-induced apoptosis and senescence in HaCat cells, in a UVA-induced photoaging model of primary human dermal fibroblasts (HDFs). Results from senescence-associated beta-galactosidase (SA-β-gal) staining revealed that rapamycin significantly reduced senescence in UVA-treated HDFs. In addition, treatment with rapamycin significantly increased cell autophagy levels, decreased the expression of p53 and phosphorylated HSP27, and reduced genotoxic and oxidative cellular stress levels in UVA-induced HDFs. Knockdown of HSP27 resulted in a significant increase of MMP-1 and MMP-3 as well as a decrease in type I collagen expression. Rapamycin mitigated these effects by activation of the classical TGF-β/Smad signaling pathway and increasing the transcriptional activity of MAPK/AP-1. Taken together, these results suggest that rapamycin may potentially serve as a preventive and therapeutic agent for UVA-induced photoaging of the skin.

Going, Toll-like receptors in skin inflammation and inflammatory diseases

The Indian Ayurvedic physicians knew the concept of inflammation dating back to 1500 BC. The continuous progress in the immunology of inflammation has explained its undiscovered mechanisms. For example, the discovery of Toll-like receptor 4 (TLR4) in humans (1997) has revolutionized the field of infection biology and innate immunity. The laboratory mice have shown twelve TLRs and express TLR10 (CD290) as a disrupted pseudogene, and humans have ten functional TLRs. Now, it is well established that TLRs play a significant role in different infectious and inflammatory diseases. Skin inflammation and other associated inflammatory diseases, including atopic dermatitis (AD), acne vulgaris, and psoriasis, along with many skin cancers are major health problems all over the world. The continuous development in the immunopathogenesis of inflammatory skin diseases has opened the window of opportunity for TLRs in studying their role. Hence, the manuscript explores the role of different TLRs in the pathogenesis of skin inflammation and associated inflammatory diseases. The article starts with the concept of inflammation, its origin, and the impact of TLRs discovery on infection and inflammation biology. The subsequent section describes the burden of skin-associated inflammatory diseases worldwide and the effect of the geographical habitat of people affecting it. The third section explains skin as an immune organ and explains the expression of different TLRs on different skin cells, including keratinocytes, Langerhans cells (LCs), skin fibroblasts, and melanocytes. The fourth section describes the impact of TLRs on these cells in different skin-inflammatory conditions, including acne vulgaris, AD, psoriasis, and skin cancers. The article also discusses the use of different TLR-based therapeutic approaches as specific to these inflammatory skin diseases.

Gold Nanoparticles Using Ecklonia stolonifera Protect Human Dermal Fibroblasts from UVA-Induced Senescence through Inhibiting MMP-1 and MMP-3

The effect of gold nanoparticles (GNPs) synthesized in marine algae has been described in the context of skin, where they have shown potential benefit. Ecklonia stolonifera (ES) is a brown algae that belongs to the Laminariaceae family, and is widely used as a component of food and medicine due to its biological activities. However, the role of GNPs underlying cellular senescence in the protection of Ecklonia stolonifera gold nanoparticles (ES-GNPs) against UVA irradiation is less well known. Here, we investigate the antisenescence effect of ES-GNPs and the underlying mechanism in UVA-irradiated human dermal fibroblasts (HDFs). The DPPH and ABTS radical scavenging activity of ES extracts was analyzed. These analyses showed that ES extract has potent antioxidant properties. The facile and optimum synthesis of ES-GNPs was established using UV-vis spectra. The surface morphology and crystallinity of ES-GNPs were demonstrated using high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). ES-GNPs presented excellent photocatalytic activity, as shown by the photo-degradation of methylene blue and rhodamine B. A cellular senescence model was established by irradiating HDFs with UVA. UVA-irradiated HDFs exhibited increased expression of senescence-associated β-galactosidase (SA-β-galactosidase). However, pretreatment with ES-GNPs resulted in reduced SA-β-galactosidase activity in UVA-irradiated HDFs. Intracellular ROS levels and G1 arrest in UVA-irradiated HDFs were checked against the background of ES-GNP treatment to investigate the antisenescence effects of ES-GNPs. The results showed that ES-GNPs significantly inhibit UVA-induced ROS levels and G1 arrest. Importantly, ES-GNPs significantly downregulated the transcription and translation of MMP (matrix metalloproteinases)-1/-3, which regulate cellular senescence in UVA-irradiated HDFs. These findings indicate that our optimal ES-GNPs exerted an antisenescence effect on UVA-irradiated HDFs by inhibiting MMP-1/-3 expression. Collectively, we posit that ES-GNPs may potentially be used to treat photoaging of the skin.

Effect of UVA radiation on the Nrf2 signalling pathway in human skin cells

The harmful effects of low energy UVA photons (315-400 nm) are associated with the massive production of reactive oxygen species resulting in oxidative stress. In response to oxidative damage, NF-E2-related factor 2 (Nrf2) is translocated to the nucleus and drives the expression of detoxication and antioxidant enzymes. UVA's effect on Nrf2 has been quite well characterised in dermal fibroblasts. However, there is a dearth of such information for keratinocytes. This study aimed to evaluate and compare the effect of UVA radiation on the Nrf2 pathway and oxidative stress related proteins in primary human dermal fibroblasts (NHDF), epidermal keratinocytes (NHEK) and human keratinocyte cell line HaCaT. NHDF were exposed to doses of 2.5-7.5 J/cm², NHEK and HaCaT to 10-20 J/cm² using a solar simulator. Effects on Nrf2 translocation were evaluated after 1, 3 and 6 h and Nrf2-controlled proteins (heme oxygenase 1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione reductase (GSR), glutathione-S-transferase (GST), interleukine-6 (IL-6), and matrix metalloproteinases (MMP-1, MMP-2)) after 3, 6 and 24 h. The results showed the fastest Nrf2 translocation was in UVA-irradiated HaCaT (1 h), persisting until the subsequent time interval (3 h), while in primary keratinocytes the effect of radiation was minimal. In NHDF, UVA-stimulated Nrf2 translocation was conspicuous 3 h after UVA treatment. In NHDF, most of the studied proteins (NQO1, HO-1, GSR, GSTM1 and MMP-1) showed the highest level 24 h after UVA exposure, except for MMP-2 and IL-6 which had their highest level at a shorter time incubation interval (3 h). In NHEK, NQO1, HO-1 and GST were increased 6 h after UVA exposure, GSR and MMP-2 level was slightly below or above the control level, and MMP-1 and IL-6 increased at shorter time intervals. When comparing NHEK and HaCaT, these cells displayed contrary responses in most of the Nrf2-controlled proteins. Thus, primary keratinocytes cannot be replaced with HaCaT when studying cell signalling such as the Nrf2 driven pathway and Nrf2-controlled proteins.

Coxsackievirus B3 Infection of Human Neural Progenitor Cells Results in Distinct Expression Patterns of Innate Immune Genes

Coxsackievirus B3 (CVB3), a member of Picornaviridae family, is an important human pathogen that causes a wide range of diseases, including myocarditis, pancreatitis, and meningitis. Although CVB3 has been well demonstrated to target murine neural progenitor cells (NPCs), gene expression profiles of CVB3-infected human NPCs (hNPCs) has not been fully explored. To characterize the molecular signatures and complexity of CVB3-mediated host cellular responses in hNPCs, we performed QuantSeq 3′ mRNA sequencing. Increased expression levels of viral RNA sensors (RIG-I, MDA5) and interferon-stimulated genes, such as IFN-β, IP-10, ISG15, OAS1, OAS2, Mx2, were detected in response to CVB3 infection, while IFN-γ expression level was significantly downregulated in hNPCs. Consistent with the gene expression profile, CVB3 infection led to enhanced secretion of inflammatory cytokines and chemokines, such as interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1). Furthermore, we show that type I interferon (IFN) treatment in hNPCs leads to significant attenuation of CVB3 RNA copy numbers, whereas, type II IFN (IFN-γ) treatment enhances CVB3 replication and upregulates suppressor of cytokine signaling 1/3 (SOCS) expression levels. Taken together, our results demonstrate the distinct molecular patterns of cellular responses to CVB3 infection in hNPCs and the pro-viral function of IFN-γ via the modulation of SOCS expression.

TLR4 in skin cancer: From molecular mechanisms to clinical interventions

The health and economic burden imposed by skin cancer is substantial, creating an urgent need for the development of improved molecular strategies for its prevention and treatment. Cutaneous exposure to solar ultraviolet (UV) radiation is a causative factor in skin carcinogenesis, and TLR4-dependent inflammatory dysregulation is an emerging key mechanism underlying detrimental effects of acute and chronic UV exposure. Direct and indirect TLR4 activation, upstream of inflammatory signaling, is elicited by a variety of stimuli, including pathogen-associated molecular patterns (such as lipopolysaccharide) and damage-associated molecular patterns (such as HMGB1) that are formed upon exposure to environmental stressors, such as solar UV. TLR4 involvement has now been implicated in major types of skin malignancies, including nonmelanoma skin cancer, melanoma and Merkel cell carcinoma. Targeted molecular interventions that positively or negatively modulate TLR4 signaling have shown promise in translational, preclinical, and clinical investigations that may benefit skin cancer patients in the near future.