β-Ionone Attenuates Dexamethasone-Induced Suppression of Collagen and Hyaluronic Acid Synthesis in Human Dermal Fibroblasts

The Role of Cyclic Adenosine Monophosphate (cAMP) in Modulating Glucocorticoid Receptor Signaling and Its Implications on Glucocorticoid-Related Collagen Loss

Glucocorticoid receptors (GRs) play a pivotal role in the stress response of the body, but overactivation can disrupt normal physiological functions. This study explores the role of cyclic adenosine monophosphate (cAMP) in GR activation and the associated mechanisms. We initially used the human embryonic kidney 293 cell line (HEK293) and found that cAMP enhancement, using forskolin and 3-isobutyl-1-methylxanthine (IBMX), did not alter glucocorticoid signaling under normal conditions, as evidenced by glucocorticoid response element (GRE) activity and the translocation of GR. However, in stressful conditions induced by dexamethasone, a synthetic glucocorticoid, cAMP was found to lessen glucocorticoid signaling within a short time frame but amplify it over an extended period in HEK293 cells. Bioinformatic analysis revealed that cAMP upregulation triggers the extracellular signal-regulated kinase (ERK) pathway, which influences GR translocation and ultimately regulates its activity. This stress-modulating function of cAMP was also investigated in the Hs68 dermal fibroblast line, known for its susceptibility to glucocorticoids. We found that cAMP enhancement via forskolin reduces GRE activity and reverses collagen loss in Hs68 cells exposed to dexamethasone. These findings underline the context-specific role of cAMP signaling in managing glucocorticoid signaling and its potential therapeutic application in treating stress-related pathological conditions like skin aging characterized by collagen reduction.

Reviewing the Regulators of COL1A1

The collagen family contains 28 proteins, predominantly expressed in the extracellular matrix (ECM) and characterized by a triple-helix structure. Collagens undergo several maturation steps, including post-translational modifications (PTMs) and cross-linking. These proteins are associated with multiple diseases, the most pronounced of which are fibrosis and bone diseases. This review focuses on the most abundant ECM protein highly implicated in disease, type I collagen (collagen I), in particular on its predominant chain collagen type I alpha 1 (COLα1 (I)). An overview of the regulators of COLα1 (I) and COLα1 (I) interactors is presented. Manuscripts were retrieved searching PubMed, using specific keywords related to COLα1 (I). COL1A1 regulators at the epigenetic, transcriptional, post-transcriptional and post-translational levels include DNA Methyl Transferases (DNMTs), Tumour Growth Factor β (TGFβ), Terminal Nucleotidyltransferase 5A (TENT5A) and Bone Morphogenic Protein 1 (BMP1), respectively. COLα1 (I) interacts with a variety of cell receptors including integrinβ, Endo180 and Discoidin Domain Receptors (DDRs). Collectively, even though multiple factors have been identified in association to COLα1 (I) function, the implicated pathways frequently remain unclear, underscoring the need for a more spherical analysis considering all molecular levels simultaneously.

Identification of Glucocorticoid Receptor Target Genes That Potentially Inhibit Collagen Synthesis in Human Dermal Fibroblasts

Over several decades, excess glucocorticoids (GCs) of endogenous or exogenous origin have been recognized to significantly inhibit collagen synthesis and accelerate skin aging. However, little is known regarding their molecular mechanisms. We hypothesized that the action of GCs on collagen production is at least partially through the glucocorticoid receptor (GR) and its target genes, and therefore aimed to identify GR target genes that potentially inhibit collagen synthesis in Hs68 human dermal fibroblasts. We first confirmed that dexamethasone, a synthetic GC, induced canonical GR signaling in dermal fibroblasts. We then collected 108 candidates for GR target genes reported in previous studies on GR target genes and verified that 17 genes were transcriptionally upregulated in dexamethasone-treated dermal fibroblasts. Subsequently, by individual knockdown of the 17 genes, we identified that six genes, AT-rich interaction domain 5B, FK506 binding protein 5, lysyl oxidase, methylenetetrahydrofolate dehydrogenase (NADP + dependent) 2, zinc finger protein 36, and zinc fingers and homeoboxes 3, are potentially involved in GC-mediated inhibition of collagen synthesis. The present study sheds light on the molecular mechanisms of GC-mediated skin aging and provides a basis for further research on the biological characteristics of individual GR target genes.

Dexamethasone Is Not Sufficient to Facilitate Tenogenic Differentiation of Dermal Fibroblasts in a 3D Organoid Model

Self-assembling three-dimensional organoids that do not rely on an exogenous scaffold but maintain their native cell-to-cell and cell-to-matrix interactions represent a promising model in the field of tendon tissue engineering. We have identified dermal fibroblasts (DFs) as a potential cell type for generating functional tendon-like tissue. The glucocorticoid dexamethasone (DEX) has been shown to regulate cell proliferation and facilitate differentiation towards other mesenchymal lineages. Therefore, we hypothesized that the administration of DEX could reduce excessive DF proliferation and thus, facilitate the tenogenic differentiation of DFs using a previously established 3D organoid model combined with dose-dependent application of DEX. Interestingly, the results demonstrated that DEX, in all tested concentrations, was not sufficient to notably induce the tenogenic differentiation of human DFs and DEX-treated organoids did not have clear advantages over untreated control organoids. Moreover, high concentrations of DEX exerted a negative impact on the organoid phenotype. Nevertheless, the expression profile of tendon-related genes of untreated and 10 nM DEX-treated DF organoids was largely comparable to organoids formed by tendon-derived cells, which is encouraging for further investigations on utilizing DFs for tendon tissue engineering.

Iris Pallida Extract Alleviates Cortisol-Induced Decrease in Type 1 Collagen and Hyaluronic Acid Syntheses in Human Skin Cells

Excessive endogenous or exogenous levels of the stress hormone cortisol have negative effects on various tissues, including the skin. Iris pallida (IP), used in traditional medicine and perfumes, exhibits biological activities, such as antioxidant and anti-inflammatory activities. In this study, we aimed to investigate the inhibitory effect of IP extract (IPE) on cortisol activity in human skin cells. We found that IPE alleviated the cortisol-induced decrease in the levels of procollagen type 1 and hyaluronic acid (HA), which were significantly recovered by 106% and 31%, respectively, compared with cortisol-induced reductions. IPE also rescued the suppression of the gene expression of COL1A1 and the HA synthases HAS2 and HAS3 in cortisol-exposed cells. Moreover, IPE blocked the cortisol-induced translocation of the glucocorticoid receptor (GR) from the cytoplasm to the nucleus as effectively as the GR inhibitor mifepristone. Analysis using a high-performance liquid chromatography-diode-array detector system revealed that irigenin, an isoflavone, is the main component of IPE, which restored the cortisol-induced reduction in collagen type 1 levels by 82% relative to the cortisol-induced decrease. Our results suggest that IPE can act as an inhibitor of cortisol in human skin cells, preventing cortisol-induced collagen and HA degradation by blocking the nuclear translocation of the GR. Therefore, IPE may be used as a cosmetic material or herbal medicine to treat stress-related skin changes.

Profound Effects of Dexamethasone on the Immunological State, Synthesis and Secretion Capacity of Human Testicular Peritubular Cells

The functions of human testicular peritubular cells (HTPCs), forming a small compartment located between the seminiferous epithelium and the interstitial areas of the testis, are not fully known but go beyond intratesticular sperm transport and include immunological roles. The expression of the glucocorticoid receptor (GR) indicates that they may be regulated by glucocorticoids (GCs). Herein, we studied the consequences of the GC dexamethasone (Dex) in cultured HTPCs, which serves as a unique window into the human testis. We examined changes in cytokines, mainly by qPCR and ELISA. A holistic mass-spectrometry-based proteome analysis of cellular and secreted proteins was also performed. Dex, used in a therapeutic concentration, decreased the transcript level of proinflammatory cytokines, e.g., IL6, IL8 and MCP1. An siRNA-mediated knockdown of GR reduced the actions on IL6. Changes in IL6 were confirmed by ELISA measurements. Of note, Dex also lowered GR levels. The proteomic results revealed strong responses after 24 h (31 significantly altered cellular proteins) and more pronounced ones after 72 h of Dex exposure (30 less abundant and 42 more abundant cellular proteins). Dex also altered the composition of the secretome (33 proteins decreased, 13 increased) after 72 h. Among the regulated proteins were extracellular matrix (ECM) and basement membrane components (e.g., FBLN2, COL1A2 and COL3A1), as well as PTX3 and StAR. These results pinpoint novel, profound effects of Dex in HTPCs. If transferrable to the human testis, changes specifically in ECM and the immunological state of the testis may occur in men upon treatment with Dex for medical reasons.

Pyracantha fortuneana (Maxim.) Li: A comprehensive review of its phytochemistry, pharmacological properties, and product development

Pyracantha fortuneana (Maxim.) Li has been used as a herbal medicine in China in its long history. Since ancient times, the fruits of P. fortuneana has been considered a functional food to improve various diseases. Many bioactive substances, including proanthocyanidins, phenols, polysaccharides, and dietary fibers, have been isolated and identified from the P. fortuneana, which possess diverse biological properties both in vitro and in vivo. Although the researches on the P. fortuneana have achieved extensive progress, the systematic study of its biological activities is still relatively lacking. In addition, accumulating researches focus on the landscape value of the P. fortuneana and the development of its by-products. The by-products of P. fortuneana, which show good development potentials in the field of agricultural production and environmental protection, are important for improving the economic value of P. fortuneana and its significance. After extensive reviewing and analyzing the existing published articles, books, and patents, this study aims to a systematic and summarized research trends of P. fortuneana and its phytochemical compositions, nutritional values, pharmacological effects and health benefits of its extracts/monomers, which would be beneficial for the future development of this medicinal plant as functional food or drugs.

The long winding road to the safer glucocorticoid receptor (GR) targeting therapies

Glucocorticoids (Gcs) are widely used to treat inflammatory diseases and hematological malignancies, and despite the introduction of novel anti-inflammatory and anti-cancer biologics, the use of inexpensive and effective Gcs is expected to grow. Unfortunately, chronic treatment with Gcs results in multiple atrophic and metabolic side effects. Thus, the search for safer glucocorticoid receptor (GR)-targeted therapies that preserve therapeutic potential of Gcs but result in fewer adverse effects remains highly relevant. Development of selective GR agonists/modulators (SEGRAM) with reduced side effects, based on the concept of dissociation of GR transactivation and transrepression functions, resulted in limited success, and currently focus has shifted towards partial GR agonists. Additional approach is the identification and inhibition of genes associated with Gcs specific side effects. Others and we recently identified GR target genes REDD1 and FKBP51 as key mediators of Gcs-induced atrophy, and selected and validated candidate molecules for REDD1 blockage including PI3K/Akt/mTOR inhibitors. In this review, we summarized classic and contemporary approaches to safer GR-mediated therapies including unique concept of Gcs combination with REDD1 inhibitors. We discussed protective effects of REDD1 inhibitors against Gcs–induced atrophy in skin and bone and underlined the translational potential of this combination for further development of safer and effective Gcs-based therapies.

Dermal Olfactory Receptor OR51B5 Is Essential for Survival and Collagen Synthesis in Human Dermal Fibroblast (Hs68 Cells)

Skin dermis comprises extracellular matrix components, mainly collagen fibers. A decrease in collagen synthesis caused by several factors, including ultraviolet (UV) irradiation and stress, eventually causes extrinsic skin aging. Olfactory receptors (ORs) were initially considered to be specifically expressed in nasal tissue, but several ORs have been reported to be present in other tissues, and their biological roles have recently received increasing attention. In this study, we aimed to characterize the role of ORs in cell survival and collagen synthesis in dermal fibroblasts. We confirmed that UVB irradiation and dexamethasone exposure significantly decreased cell survival and collagen synthesis in Hs68 dermal fibroblasts. Moreover, we demonstrated that the mRNA expression of 10 ORs detectable in Hs68 cells was significantly downregulated in aged conditions compared with that in normal conditions. Thereafter, by individual knockdown of the 10 candidate ORs, we identified that only OR51B5 knockdown leads to a reduction of cell survival and collagen synthesis. OR51B5 knockdown decreased cAMP levels and dampened the downstream protein kinase A/cAMP-response element binding protein pathway, downregulating the survival- and collagen synthesis-related genes in the dermal fibroblasts. Therefore, OR51B5 may be an interesting candidate that plays a role in cell survival and collagen synthesis.