Effects of dexamethasone, a synthetic glucocorticoid, on human periodontal ligament stem cells

Apoptosis Evaluation in Circulating CD34+-Enriched Hematopoietic Stem and Progenitor Cells in Patients with Abnormally Increased Production of Endogenous Glucocorticoids in Course of Cushing's Syndrome

Abnormalities in hematological parameters of peripheral blood have been noted in patients with endogenous Cushing's Syndrome (CS) in the corticotropin (ACTH)-dependent and ACTH-independent forms. Nevertheless, the exact mechanism of glucocorticoids (GCs) action on human hematopoiesis is still not entirely clear. The aim of the study was to determine whether endogenous excessive production of GCs could affect apoptosis of CD34+ cells enriched in hematopoietic stem and progenitor cells (HSPCs) collected from the peripheral blood of newly diagnosed CS patients. Flow cytometry, Annexin-V enzyme-linked immunosorbent assay, TUNEL assay, real-time quantitative PCR, and microarray RNA/miRNA techniques were used to characterize CS patients' HSPCs. We found that the glucocorticoid receptor (GR) protein expression levels in CS were higher than in healthy controls. A complex analysis of apoptotic status of CS patients' HSPC cells showed that GCs significantly augmented apoptosis in peripheral blood-derived CD34+ cells and results obtained using different methods to detect early and late apoptosis in analyzed cell population were consistent. CS was also associated with significant upregulation in several members of the BCL-2 superfamily and other genes associated with apoptosis control. Furthermore, global gene expression analysis revealed significantly higher expression of genes associated with programmed cell death control in HSPCs from CS patients. These findings suggest that human endogenous GCs have a direct pro-apoptotic activity in hematopoietic CD34+ cells derived from CS subjects before treatment.

Dexamethasone-loaded zeolitic imidazolate frameworks nanocomposite hydrogel with antibacterial and anti-inflammatory effects for periodontitis treatment

Periodontitis is a bacterial-induced, chronic inflammatory disease characterized by progressive destruction of tooth-supporting structures. Pathogenic bacteria residing in deep periodontal pockets after traditional manual debridement can still lead to local inflammatory microenvironment, which remains a challenging problem and an urgent need for better therapeutic strategies. Here, we integrated the advantages of metal-organic frameworks (MOFs) and hydrogels to prepare an injectable nanocomposite hydrogel by incorporating dexamethasone-loaded zeolitic imidazolate frameworks-8 (DZIF) nanoparticles into the photocrosslinking matrix of methacrylic polyphosphoester (PPEMA) and methacrylic gelatin (GelMA). The injectable hydrogel could be easily injected into deep periodontal pockets, achieving high local concentrations without leading to antibiotic resistance. The nanocomposite hydrogel had high antibacterial activity and constructs with stable microenvironments maintain cell viability, proliferation, spreading, as well as osteogenesis, and down-regulated inflammatory genes expression in vitro. When evaluated on an experimental periodontitis rat model, micro-computed tomography and histological analyses showed that the nanocomposite hydrogel effectively reduced periodontal inflammation and attenuated inflammation-induced bone loss in a rat model of periodontitis. These findings suggest that the nanocomposite hydrogel might be a promising therapeutic candidate for treating periodontal disease.

The psychobiological links between chronic stress-related diseases, periodontal/peri-implant diseases, and wound healing

Chronic stress is a relevant disease to periodontal practice, encompassing 25%-28% of the US population (American Psychological Association 2015). While it is well established that chronic psychologic stress can have significant deleterious systemic effects, only in recent decades have we begun to explore the biochemical, microbial, and physiologic impacts of chronic stress diseases on oral tissues. Currently, chronic stress is classified as a "risk indicator" for periodontal disease. However, as the evidence in this field matures with additional clinically controlled trials, more homogeneous data collection methods, and a better grasp of the biologic underpinnings of stress-mediated dysbiosis, emerging evidence suggests that chronic stress and related diseases (depression, anxiety) may be significant contributing factors in periodontal/peri-implant disease progression and inconsistent wound healing following periodontal-related therapeutics. Ideal solutions for these patients include classification of the disease process and de-escalation of chronic stress conditions through coping strategies. This paper also summarizes periodontal/implant-related therapeutic approaches to ensure predictable results for this specific patient subpopulation.

Long noncoding RNA ANCR suppresses bone formation of periodontal ligament stem cells via sponging miRNA-758

Long noncoding RNAs (lncRNAs) were proposed to be important regulators influencing various differentiation processes. Yet, the molecular mechanisms of lncRNAs governing osteogenic differentiation of Periodontal Ligament Stem Cells (PDLSCs) remain unclear. Here, PDLSCs were isolated from normal periodontal ligament of human (PDL) whereas P-PDLSCs were isolated from periodontitis affected PDL. Quantitative real-time PCR (qRT-PCR) was performed to examine the relative expression level of lncRNA-ANCR and of Osterix (OSX), Alkaline Phosphatase (ALP) as well as Runt-related transcription factor 2 (RUNX2) in PDLSCs. Gain- and loss-of- function experiments was performed to study the role of lncRNA-ANCR. Alizarin Red staining was used to evaluate the function of lncRNA-ANCR and miRNA-758 on osteogenic differentiation. In addition, via dual luciferase reporter assay and RNA immunoprecipitation the microRNA sponge potential of lncRNA-ANCR was assessed. A luciferase reporter assay identified the correlation between miR-758 and Notch2. Our results showed that the expression of ALP, RUNX2 and OSX were increased whereas lncRNA-ANCR was decreased during the process of differentiation in PDLSCs. Overexpression of lncRNA-ANCR decreased the expression of ALP, RUNX2 and OSX as confirmed by Alizarin red staining. Overexpression of lncRNA-ANCR resulted in reduction of the miR-758 expression level. Furthermore, RNA immunoprecipitation proved that lncRNA-ANCR targets miR-758 directly. The results of dual luciferase reporter assay also demonstrated that miR-758 regulated Notch2 expression by targeting 3'-UTR of Notch2. In conclusion, the novel pathway lncRNA-ANCR/miR-758/Notch2 plays an important role in the process of regulating osteogenic differentiation of PDLSCs.

Prostaglandin D2-Mediated DP2 and AKT Signal Regulate the Activation of Androgen Receptors in Human Dermal Papilla Cells

Prostaglandin D2 (PGD2) and prostaglandin D2 receptor 2 (DP2) is known to be an important factor in androgenetic alopecia (AGA). However, the effect of PGD2 in human dermal papilla cells (hDPCs) is not fully understood. The function of PGD2-induced expression of the androgen receptor (AR), DP2, and AKT (protein kinase B) signal were examined by using real time-PCR (qRT-PCR), western blot analysis, immunocytochemistry (ICC), and siRNA transfection system. PGD2 stimulated AR expression and AKT signaling through DP2. PGD2 stimulated AR related factors (transforming growth factor beta 1 (TGFβ1), Creb, lymphoid enhancer binding factor 1 (LEF1), and insulin-like growth factor 1, (IGF-1)) and AKT signaling (GSK3β and Creb) on the AR expression in hDPCs. However, these factors were down-regulated by DP2 antagonist (TM30089) and AKT inhibitor (LY294002) as well as DP2 knockdown in hDPCs decreased AR expression and AKT signaling. Finally, we confirmed that PGD2 stimulates the expression of AR related target genes, and that AKT and its downstream substrates are involved in AR expression on hDPCs. Taken together, our data suggest that PGD2 promotes AR and AKT signal via DP2 in hDPCs, thus, PGD2 and DP2 signal plays a critical role in AR expression. These findings support the additional explanation for the development of AGA involving PGD2-DP2 in hDPCs.

Dickkopf-1 is involved in dexamethasone-mediated hair follicle regression

The stress-related neurohormones including glucocorticoids (GCs) are secreted by hair follicles (HFs), and GCs suppress murine hair growth in vivo. In this study, we found that dexamethasone (Dex), a synthetic GC, increased the expression of dickkopf-1 (DKK1), a known catagen inducer, in dermal papilla (DP) cells, but not in follicular keratinocytes. The neutralizing DKK1 antibody significantly attenuated the Dex-induced inhibition of human hair shaft elongation. In addition, the neutralizing Dkk1 antibody delayed Dex-induced catagen in mice. Collectively, our data strongly suggest that stress-related neurohormones cause DP cells to secrete DKK1, thereby leading to stress-associated disturbances in hair growth.

Easy-to-use strategy for reference gene selection in quantitative real-time PCR experiments

Real-time PCR is an indispensable technique for mRNA expression analysis but conclusions depend on appropriate reference gene selection. However, while reference gene selection has been a topic of publications, this issue is often disregarded when measuring target mRNA expression. Therefore, we (1) evaluated the frequency of appropriate reference gene selection, (2) suggest an easy-to-use tool for least variability reference gene selection, (3) demonstrate application of this tool, and (4) show effects on target gene expression profiles. All 2015 published articles in Naunyn-Schmiedeberg's Archives of Pharmacology were screened for the use of quantitative real-time PCR analysis and selection of reference genes. Target gene expression (Vegfa, Grk2, Sirt4, and Timp3) in H9c2 cells was analyzed following various interventions (hypoxia, hyperglycemia, and/or isoflurane exposure with and without subsequent hypoxia) in relation to putative reference genes (Actb, Gapdh, B2m, Sdha, and Rplp1) using the least variability method vs. an arbitrarily selected but established reference gene. In the vast majority (18 of 21) of papers, no information was provided regarding selection of an appropriate reference gene. In only 1 of 21 papers, a method of appropriate reference gene selection was described and in 2 papers reference gene selection remains unclear. The method of reference gene selection had major impact on interpretation of target gene expression. With hypoxia, for instance, the least variability gene was Rplp1 and target gene expression (Vefga) heavily showed a 2-fold up-regulation (p = 0.022) but no change (p = 0.3) when arbitrarily using Gapdh. Frequency of appropriate reference gene selection in this journal is low, and we propose our strategy for reference gene selection as an easy tool for proper target gene expression.