Fibulin-6 expression and anoikis in human salivary gland epithelial cells: implications in Sjogren’s syndrome

Important changes in acinar and ductal morphology and function, together with pronounced extracellular matrix (ECM) remodelling, are detectable in the labial salivary glands of Sjögren's syndrome (SS) patients. The objective of this work was to determine the effect of treatment with the anti-Ro/SSA auto-antibodies, characterizing SS, on the expression of fibulin-6, a member of the fibulins family of the ECM, in primary human salivary gland epithelial cell (SGEC) cultures established from biopsies of labial minor salivary glands obtained from healthy donors. The induction of cell detachment and anoikis in SGECs treated with anti-Ro/SSA auto-antibodies were also investigated. Changes in fibulin-6 mRNA expression were measured by semi-quantitative reverse transcriptase-PCR and real-time PCR. Fibulin-6 expression in cells treated with anti-Ro/SSA auto-antibodies was evaluated by flow cytometric analysis and confocal laser scanning microscopy. SGECs undergoing death by anoikis were identified and quantified using Calcein blue/YOPRO-1 dyes. Herein, we present the first evidence of fibulin-6 expression in SGEC that results distributed in the cytoplasm surrounding the inner side of the plasma membrane. Fibulin-6 was down-regulated in SGECs treated with anti-Ro/SSA auto-antibodies in which a marked cell detachment and a reduction of cell viability were observed. Notably, a reduction of fibulin-6 expression in SGECs treated with anti-Ro/SSA auto-antibodies corresponds to an increase of anoikis cell death. Our observations demonstrate a dysregulation of fibulin-6 in the pathological processes observed in SS and provide new evidence that disorganization of the ECM environment could damage the architecture and function of the salivary glands

Saponins from Tribulus Terrestris L. protect human keratinocytes from UVB-induced damage

Chronic exposure to solar UVB radiation damages skin, increasing the risk to develop cancer. Hence the identification of compounds with a photoprotective efficacy is essential. This study examined the role of saponins derived from Tribulus terrestris L. (TT) on the modulation of apoptosis in normal human keratinocytes (NHEK) exposed to physiological doses of UVB and to evaluate their antitumoral properties. In NHEK, TT saponins attenuate UVB-induced programmed cell death through inhibition of intrinsic apoptotic pathway. In squamous cell carcinomas (SCC) TT saponins do not make the malignant keratinocytes more resistant to UVB and determine an enhanced apoptotic response. The photoprotective effect of TT saponins is tightly correlated to the enhancement of NER genes expression and the block of UVB-mediated NF-κB activation. Collectively, our study shows experimental evidence that TT has a preventive efficacy against UVB-induced carcinogenesis and the molecular knowledge on the mechanisms through which TT saponins regulate cell death suggests great potential for TT to be developed into a new medicine for cancer patients

Neuroprotective effects of vitamin C: new insight about the GSK3β signaling pathway modulation

Neuroinflammation is an inflammatory response through which the brain immune cells eliminate pathogens, cell debris or misfolded proteins. As a defence mechanism, it is finalized to the preservation of the brain, however the prolonged inflammatory status leads to the onset of neurodegenerative disorders [1]. Oxidative stress is an imbalance between free radicals and antioxidants in favour of pro- oxidants. Given that both neuroinflammation and oxidative stress are implicated in the patho- genesis of neurodegenerative disorders, antioxidants and anti-inflammatory compounds may be useful for counteracting them. Vitamin C (Vit C) is known to have anti-inflammatory and antioxidant properties and, although its neuroprotective effects have been elucidated, the underlying molecular mechanisms remain unclear [2]. Glycogen synthase kinase 3β (GSK3β) is a serine/threonine kinase which acts as a potent driver of inflammation, rendering GSK3β inhibitors a promising target of anti-inflammatory research [3]. In this study, we have investigated the role of GSK3β inactivation in the context of Vit C neuroprotective effects by using a well-known 1-methyl-4-phenyl-1,2,3,6-tetrahydro- pyridine (MPTP)-induced preclinical animal model of Parkinson’s disease (PD) and LPS-treated BV2 cells as alternative model system for activated primary microglia cultures. We found that Vit C regulates the inflammatory response up-regulating the expression of the anti-inflammatory cytokine IL-4 and down-regulating the pro-inflammatory cytokine IL-6 both in in vitro and in vivo models. In addition, the levels of superoxide dismutase 1 (SOD1) antioxidant enzyme were increased by Vit C in both models. In response to Vit C, GSK3β pro- tein was inactivated and p-p38 underwent an increase compared to control, suggesting that p-p38 may play a role in inactivating GSK3β. Moreover, Vit C is able to increase the cytosolic levels of β-catenin and consequently its nuclear translocation, giving a possible explanation to the anti-inflammatory and antioxidant functions of Vit C. Collectively, these results demonstrate that Vit C exhibits substantial neuroprotective effects through the modulation of GSK3β path- way, attenuating pro-inflammatory and up-regulating anti-inflammatory processes