Biphasic Dose-Response and Hormetic Effects of Stress Hormone Hydrocortisone on Telomerase-Immortalized Human Bone Marrow Stem Cells In Vitro

Although high levels of stress hormones are associated with well-known negative health outcomes, their low levels can have health-promoting effects by virtue of the phenomenon of mild stress-induced hormesis. We have studied the effects of a wide range (between 100 nmol/L and 150 μmol/L) of hydrocortisone (HC) on human bone marrow stem cells in vitro. Telomerase-immortalized human mesenchymal stem cells (hTERT-MSCs) were exposed to various doses of HC for different durations (1-6 days) and analyzed for survival and metabolic activity by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, for cell migratory ability by a wound-healing assay and for osteoblastic and adipogenic differentiation abilities in vitro. Our findings indicate that hTERT-MSCs exposed to HC resulted in a biphasic hormetic dose–response in some measures but not all. Although the mitochondrial and metabolic MTT activity assay clearly showed low-level stimulatory (between 0.1 and 1 µmol/L) and high-level inhibitory effects (from about 10 µmol/L onward), the cytostatic and differentiation-inducing effects were mostly linear at concentrations between 1 and 100 µmol/L. Further long-term studies will elucidate whether chronic or intermittent exposure of human cells to stress hormones has physiologically beneficial hormetic effects.

Role of neuropeptides, neurotrophins, and neurohormones in skin wound healing

Due to the close interactions between the skin and peripheral nervous system, there is increasing evidence that the cutaneous innervation is an important modulator of the normal wound healing process. The communication between sensory neurons and skin cells involves a variety of molecules (neuropeptides, neurohormones, and neurotrophins) and their specific receptors expressed by both neuronal and nonneuronal skin cells. It is well established that neurotransmitters and nerve growth factors released in skin have immunoregulatory roles and can exert mitogenic actions; they could also influence the functions of the different skin cell types during the wound healing process.

The glycosylated IgII extracellular domain of EMMPRIN is implicated in the induction of MMP-2

EMMPRIN is a widely expressed transmembrane glycoprotein that plays important roles in many physiological and pathological processes, such as tumor invasion and metastasis. It stimulates the production of matrix metalloproteinase (MMPs) by tumor-associated fibroblasts. In the present study, our aim was to (a) to investigate if the IgII loop domain of the extracellular domain (ECD) of EMMPRIN contributes to the MMP production by fibroblasts and (b) to evaluate the significance of glycosylation in this process. For this purpose, we expressed the ECD, IgI, or IgII domains of EMMPRIN, in their glycosylated and non-glycosylated forms, in the heterologous expression systems of P. pastoris and E. coli, respectively. Dermal fibroblasts were treated with purified recombinant domains and proteins from cell extracts and supernatants were analyzed by Western blot and zymography assays. Fibroblasts treated with ECD-, IgI-, and IgII-glycosylated domains of EMMPRIN significantly stimulated the gelatinolytic activity of MMP-2, compared to untreated fibroblasts, whereas no significant effect was observed after treatment with the non-glycosylated ECD, IgI, and IgII domains. Western blot analysis from cell extracts and supernatants revealed that only the glycosylated forms were able to stimulate MMP-2 production and secretion, respectively. Quantitative PCR revealed that this effect was not attributed to transcriptional alterations. This study showed that N-glycosylation was a prerequisite for efficient MMP-2 production, with the IgII loop domain contributing significantly to this process. Perturbation of the function of IgII-EMMPRIN loop could have potential therapeutic value in the inhibition of MMP-2-dependent cancer cell invasion and metastasis.

Knockdown of paraoxonase 1 expression influences the ageing of human dermal microvascular endothelial cells

Skin is one of the most commonly studied tissues for microcirculation research owing to its close correlation of cutaneous vascular function, ageing and age-related cardiovascular events. To elucidate proteins that determine this correlation between endothelial cell function and ageing in the vascular environment of the skin, we performed a proteomic analysis of plasma samples from six donors in their 20s (young) and six donors in their 60s (old). Among identified proteins, paraoxonase 1 (PON1) was selected in this study. To elucidate the role of PON1 on skin ageing and determine how it controls cellular senescence, the characteristics of PON1 in human dermal microvascular endothelial cells (HDMECs) were determined. When the expression of endogenous PON1 was knocked-down by small interfering RNA (siRNA) targeting PON1, HDMECs showed characteristic features of cellular senescence such as increases in senescence-associated β-galactosidase stained cells and enlarged and flattened cell morphology. At 48 h post-transfection, the protein expression of p16 in PON1 siRNA-treated HDMECs was higher than that in scrambled siRNA-treated HDMECs. In addition, the expressions of moesin and rho GTP dissociation inhibitor, additional age-related candidate biomarkers, were decreased by PON1 knock-down in HDMECs. In conclusion, these results suggest that PON1 functions as an ageing-related protein and plays an important role in the cellular senescence of HDMECs.

Shortened treatment duration of glucocorticoid-induced skin atrophy in rats

Glucocorticoids (GCs) belong to the most widely used anti-inflammatory drugs at all. However, their topical use is limited by their side effect potential, with skin atrophy being the most prominent one. Thus, determining the atrophogenic potential of novel compounds is of importance for drug development. Currently, the most frequently performed model in the base and pharmaceutical research is the hr/hr rat model of GC-induced skin atrophy that lasts for 19 days. In this study, we analysed statistically skin atrophy experiments retrospectively to ascertain (i) the earliest time-point, at which skin atrophy is significantly induced; and (ii) whether the differences between the GC treatment groups change until the end of the experiment. We show here that the treatment duration of rat skin atrophy models might be reduced to 5 days for economical and ethical reasons.