Zinc inhibits high glucose-induced apoptosis in peritoneal mesothelial cells

Circulating sFasL Levels Predict the Severity and Outcome of Burn Injury: A Prospective Observational Study

BACKGROUND

Severe burn injury activates shock, inflammation, and blood cell system, but inappropriate reactions may lead to adverse outcomes. Soluble Fas ligand (sFasL) participates in apoptosis and inflammatory response. The circulating sFasL levels we investigated in association with the burn severity, shock, inflammation, blood cells, and mortality in patients with severe burns.

METHODS

A total of 56 patients with severe burns were recruited. The levels of sFasL and the biomarkers reflecting shock, organ damage, inflammation, and blood cells at 48 h postburn were analyzed. We compared the practical situation of patients that stratified by median sFasL levels and investigated the predictive value of sFasL for mortality.

RESULTS

High circulating sFasL levels were associated with the higher degrees of burn index, shock index, lactate, N-terminal probrain natriuretic peptide, total bilirubin, blood urea nitrogen, creatinine, tumor necrosis factor-α, interleukin-1β, interleukin-8, intercellular adhesion molecule 1, and complement 3, and the lower degrees of oxygenation index, lymphocytes, and platelets. Multiple linear regression analysis showed that the higher tumor necrosis factor-α (P < 0.001) and the lower oxygenation index (P = 0.031) and lymphocytes (P = 0.043) were associated with the higher sFasL. High sFasL (a unit is 50 ng/L) (odds ratio [OR] 5.50 [95% CI 1.04-29.20], P = 0.045) was an independent predictor of increased mortality by multivariate logistic regression analysis.

CONCLUSIONS

High circulating sFasL at 48 h postburn in patients with severe burns reflect shock, proinflammatory response, organ damage, and lymphocyte reductions and predict 30-day mortality.

Zinc supplementation inhibits the high glucose‑induced EMT of peritoneal mesothelial cells by activating the Nrf2 antioxidant pathway

The high glucose (HG)-induced epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) serves an important role in peritoneal fibrosis (PF) during peritoneal dialysis. Our previous study reported that zinc (Zn) supplementation prevented the HG-induced EMT of rat PMCs in vitro. In the present study, the role of Zn in HG-induced EMT was investigated in vivo using a rat model of PF. Additionally, the molecular mechanisms underlying HG-induced EMT were studied in human PMCs (HPMCs). In the rat model of PF, HG treatment increased the glucose transfer capacity and decreased the ultrafiltration volume. Histopathological analysis revealed peritoneal thickening, increased expression of vimentin and decreased expression of E-cadherin. ZnSO₄ significantly ameliorated the aforementioned changes, whereas Zn inhibition by clioquinol significantly aggravated the effects of HG on rats. The effects of Zn on HPMCs was assessed using western blot analysis, Transwell assays and flow cytometry. It was revealed that Zn also significantly suppressed the extent of the EMT, and reduced reactive oxygen species production and the migratory ability of HG-induced HPMCs, whereas Zn inhibition by N',N',N',N'-tetrakis (2-pyridylmethyl) ethylenediamine significantly potentiated the HG-induced EMT of HPMCs. HG-stimulated HPMCs exhibited increased expression of nuclear factor-like 2 (Nrf2) in the nucleus, and total cellular NAD(P)H quinone dehydrogenase 1 (NQO1) and heme oxygenase-1 (HO-1), the target proteins of the Nrf2 antioxidant pathway. Zn supplementation further promoted nuclear Nrf2 expression, and increased the expression of target proteins of the Nrf2 antioxidant pathway, whereas Zn depletion decreased nuclear Nrf2, NQO1 and HO-1 expression compared with the HG group. In conclusion, Zn supplementation was proposed to suppress the effects of HG on the EMT by stimulating the Nrf2 antioxidant pathway and subsequently reducing oxidative stress in PMCs.

1,25(OH)2D3 treatment attenuates high glucose‑induced peritoneal epithelial to mesenchymal transition in mice

It has been previously demonstrated that 1,25(OH)2D3 prevents the progression of epithelial to mesenchymal transition (EMT). However, it remains unclear whether 1,25(OH)2D3 has a role in peritoneal EMT stimulated by high glucose (HG) peritoneal dialysis fluid (PDF). The present study was performed to investigate the role of 1,25(OH)2D3 in the progression of EMT in the peritoneal mesothelium. A total of 35 male Kunming mice were randomly assigned into seven groups. In the control group, no diasylate or saline was infused. In the saline group, the mice were intraperitoneally injected with saline every day for 4 weeks. In the vitamin D group, the mice were subjected to intraperitoneal injections of 1 or 5 µg/kg of 1,25(OH)2D3 once weekly (every Monday) for 4 weeks. The peritoneal dialysis (PD) group were intraperitoneally injected with a conventional 4.25% PDF daily for 4 weeks. The vitamin D+PD group were intraperitoneally injected with 4.25% PDF daily and co‑treated with 1 µg/kg or 5 µg/kg 1,25(OH)2D3 once weekly, for 4 weeks. The peritoneal morphology and thickness were assessed by hematoxylin and eosin and Masson's trichrome staining. The peritoneal protein level of EMT markers (α‑smooth muscle actin, fibronectin and E‑cadherin), vitamin D receptor (VDR), B cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X protein, transforming growth factor (TGF)‑β and Smad3 were evaluated by western blot analysis or immunohistochemical staining. Furthermore, apoptosis was assessed using a Caspase‑3 activity assay. The results demonstrated that after 4 weeks of intraperitoneal injections in mice, HG‑PDF decreased the expression of VDR, promoted EMT and apoptosis, and increased the thickness of the peritoneal membrane. However, 1,25(OH)2D3 treatment attenuated HG‑induced EMT and apoptosis, and decreased peritoneal thickness, which may partially occur through inhibition of transforming growth factor TGF‑β/Smad pathways via 1,25(OH)2D3 binding to VDR. The present study demonstrated that 1,25(OH)2D3 attenuated HG‑induced EMT and apoptosis in the peritoneal mesothelium through TGF‑β/Smad pathways. 1,25(OH)2D3 treatment in conjunction with HG dialysate may provide an improved solution to the peritoneal injury in the process of PD.

Fluctuation of ROS regulates proliferation and mediates inhibition of migration by reducing the interaction between DLC1 and CAV-1 in breast cancer cells

The aim of our present study was to elucidate the effects of up-regulation and down-regulation of intracellular reactive oxygen species (ROS) level on proliferation, migration, and related molecular mechanism. Breast cancer cells were treated by catalase or H₂O₂. MTT, colony formation assay, and Hoechst/PI staining were used to evaluate proliferation and apoptosis. The level of intracellular ROS was measured by dichlorodihydrofluorescein diacetate probes. The ability of migration was detected by wound healing. Western blotting and coimmunoprecipitation (co-IP) were used to determine the expression of DLC1 and CAV-1 and their interaction. Our data indicated that up-regulation of intracellular ROS induced by H₂O₂ significantly inhibited proliferation and induced apoptosis accompanying G1 cell cycle arrest and elevated expression of p53. For cell migration, either up-regulation or down-regulation of ROS induced migration inhibition with reduction of interaction between DLC1 and CAV-1. Our results suggested that up-regulation of intracellular ROS inhibited proliferation by promoting expression of p53 and induced G1 cycle arrest and apoptosis. Fluctuation of ROS inhibited migration through reducing the interaction between DLC1 and CAV-1.

1,25(OH)2D3 inhibits high glucose-induced apoptosis and ROS production in human peritoneal mesothelial cells via the MAPK/P38 pathway

The regulation of cell proliferation, differentiation and immunomodulation are affected by 1,25(OH)2D3. However, its function during apoptosis and oxidative stress in human peritoneal mesothelial cells (HPMCs) remains unknown. The aim of the present study was to investigate whether the regulation of apoptosis and oxidative stress have therapeutic relevance in peritoneal dialysis (PD) therapy. The present study investigated the effects of 1,25(OH)2D3 on high glucose (HG)-induced apoptosis and reactive oxygen species (ROS) production in HPMCs, and examined the underlying molecular mechanisms. Flow cytometry and western blotting were performed to detect cell apoptosis, 2,7-dichlorofluorescein diacetate was used to measure reactive oxygen species production and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to measure cell viability. The results of the present study demonstrated that exposure to HG increased apoptosis and ROS production in HPMCs, whereas pretreatment with 1,25(OH)2D3 significantly inhibited HG‑induced apoptosis and ROS production. Further analysis revealed that 1,25(OH)2D3 facilitated cell survival via the MAPK/P38 pathway. The results of the present study indicate that 1,25(OH)2D3 inhibits apoptosis and ROS production in HG‑induced HPMCs via inhibition of the MAPK/P38 pathway.

Metal levels in the liver, muscle, gill, intestine, and gonad of Lake Van fish (Chalcalburnus tarichi) with abnormal gonad

Recently, an increasing number of studies have shown that Lake Van--the biggest soda lake in the world--is polluted due to an increasing population. Studies have shown abnormalities in the Lake Van fish (Chalcalburnus tarichi), the sole fish species that inhabits the lake. Unlike the vitellogenic and mature oocytes in normal gonads, abnormal gonads show large amounts of connective tissue and young oocytes. In this study, metal levels (nickel [Ni], copper [Cu], cobalt [Co], iron [Fe], zinc [Zn], cadmium [Cd], lead [Pb], and manganese [Mn]) in the muscle, liver, gill, intestine, and gonad of Lake Van fish with normal and abnormal gonads were assessed. Further, the metal contents in the wastewater from the wastewater treatment facility situated near Lake Van in Van City were assessed. All the metal levels, except that of Zn, were high in the Lake Van environment (P<0.05). The highest metal content in the tissues was for Fe, while the lowest level was for Co. The Pb level was found to be very high in both fish groups. Cd was not found in the tissues of both fish groups. The levels of Fe, Cu, Pb, and Mn were not significant in the tissues of both normal and abnormal fish groups. Zn level was significantly high in the livers and gonads of fish with abnormal gonads, and Co level was significantly high only in the livers (P<0.05). Consequently, high levels of Zn in the liver and gonads and high levels of Co in the liver may be factors causing the abnormal gonads in the Lake Van fish.

Zinc modulates high glucose-induced apoptosis by suppressing oxidative stress in renal tubular epithelial cells

Hyperglycemia is a characteristic of diabetic nephropathy, inducing renal tubular cell apoptosis by eliciting oxidative stress and inflammation. Zinc (Zn) is known as an essential trace element in many enzymes and proteins involved in antioxidant defenses, electron transport, and exerting antiapoptotic or cytoprotective effects. In this study, the underlying mechanisms involved in the protective effects of Zn on high glucose-induced cytotoxicity were explored using cultured renal tubular epithelial cells (NRK-52E). The authors discovered that Zn supplementation inhibited high glucose (HG)-induced NRK-52E cell apoptosis by attenuating reactive oxygen species production, inhibiting HG-induced caspase-3 and caspase-9 activation, and inhibiting the release of cytochrome c from mitochondria to the cytosol. Further analysis revealed that Zn supplementation facilitated cell survival through increasing nuclear translocation of NF-E2-related factor 2 (Nrf2), leading to increased regulation of levels of two antioxidant enzymes, hemeoxygenase-1 and glutamate cysteine ligase, which provided an adaptive survival response against the HG-induced oxidative cytotoxicity. Moreover, the Zn-mediated increases in Nrf2 activity were suppressed by the pharmacological inhibition of Akt or extracellular signal-regulated kinase 1/2. Taken together, these findings suggest that Zn antiapoptosis capacity through the activation of Akt and ERK signal pathways leads to Nrf2 activation and, subsequently, Nrf2 target gene induction, thereby protecting the NRK-52E cells from HG-induced apoptosis.

INAA application in the assessment of chemical element mass fractions in adult and geriatric prostate glands

The variation with age of the mass fraction of 37 chemical elements in intact nonhyperplastic prostate of 65 healthy 21-87 year old males was investigated by instrumental neutron activation analysis with high resolution spectrometry of short- and long-lived radionuclides. Mean values (M±SΕΜ) for mass fractions (mg kg(-1), dry mass basis) of the chemical elements studied were: Ag-0.055±0.007, Br-33.2±3.3, Ca-2150±118, Cl-13014±703, Co-0.038±0.003, Cr-0.47±0.05, Fe-99.3±6.1, Hg-0.044±0.006, K-11896±356, Mg-1149±68, Mn-1.41±0.07, Na-10886±339, Rb-12.3±0.6, Sb-0.049±0.005, Sc-0.021±0.003, Se-0.65±0.03, and Zn-795±71. The mass fraction of other chemical elements measured in this study were lower than the corresponding detection limits (mg kg(-1), dry mass basis): As<0.1, Au<0.01, Ba<100, Cd<2, Ce<0.1, Cs<0.05, Eu<0.001, Gd<0.02, Hf<0.2, La<0.5, Lu<0.003, Nd<0.1, Sm<0.01, Sr<3, Ta<0.01, Tb<0.03, Th<0.05, U<0.07, Yb<0.03, and Zr<0.3. This work revealed that there is a significant trend for increase with age in mass fractions of Co (p<0.0085), Fe (p<0.037), Hg (p<0.035), Sc (p<0.015), and Zn (p<0.0014) and for a decrease in the mass fraction of Mn (p<0.018) in prostates, obtained from young adult up to about 60 years, with age. In the nonhyperplastic prostates of males in the sixth to ninth decades, the magnitude of mass fractions of all chemical element were maintained at near constant levels. Our finding of correlation between the prostatic chemical element mass fractions indicates that there is a great variation of chemical element relationships with age.

Age-related histological and zinc content changes in adult nonhyperplastic prostate glands

To clarify age-related histological and Zn content changes in nonhyperplastic adult prostate glands, a quantitative morphometric and energy-dispersive X-ray fluorescence analyses were performed. The prostates were obtained from autopsies of 63 subjects aged 21-70 years who died mainly from trauma. It was found that histologically normal prostate tissue undergoes substantial changes throughout aging. These changes are reflected in an increase of the percent volume of the glandular lumen for the third to fifth decades, reaching a maximum for the decade 41-50 years. Over the same period, the percent volume of the stroma remains steady, but the percent volume of epithelium decreases, approximately, linearly with age. The percent volume of glandular lumen (reflects the volume of prostatic fluid) in the prostate gland of men aged 41 to 50 years is 1.5-fold higher than that in men aged 21 to 30 years, but the epithelium/lumen (prostatic fluid) ratio is approximately twofold lower. This suggests that accumulation of the prostatic fluid develops from 30 to 50 years of age. This accumulation of the prostatic fluid results in an increase of the Zn mass fraction in the prostate. In turn, when the intraprostatic Zn level exceeds a certain level by the end of the fifth decade, it begins to work as a trigger for different factors, all of which increase the proliferation of stromal cells. Deductions from these results allow possible partial explanations of both relevant prostatic aging mechanisms and the effects of dietary interventions using supplementary Zn.

Zinc protects human kidney cells from depleted uranium-induced apoptosis

Depleted uranium (DU) is a weak radioactive heavy metal, and zinc (Zn) is an effective antidote to heavy metal poisoning. However, the effect of Zn on DU-induced cytotoxicity and apoptosis is not completely understood. The purpose of this study was to evaluate the effect of Zn on DU-induced cell apoptosis in human kidney cells (HK-2) and explore its molecular mechanism. Pre-treatment with Zn significantly inhibited DU-induced apoptosis. It reduced the formation of reactive oxygen species in the cells, increased the catalase (CAT) and glutathione (GSH) concentrations, suppressed the DU-induced soluble Fas receptor (sFasR) and soluble Fas ligand (sFasL) overexpression, suppressed the release of cytochrome c and apoptosis inhibitor factor (AIF) from mitochondria to cytoplasm, inhibited the activation of caspase-9, caspase-8 and caspase-3, and induced metallothionein (MT) expression. Furthermore, exogenous MT effectively inhibited DU-induced cell apoptosis. In conclusion, mitochondrial and FasR-mediated apoptosis pathways contribute to DU-induced apoptosis in HK-2 cells. Through independent mechanisms, such as indirect antioxidant effects, inhibition of the activation of caspase-9, caspase-8 and caspase-3, and induction of MT expression, Zn inhibits DU-induced apoptosis.

The effect of zinc and the role of p53 in copper-induced cellular stress responses

Metals can directly or indirectly cause an increase in reactive oxygen species (ROS) accumulation in cells, and this may result in programmed cell death. A number of previous studies have shown that zinc (Zn) modulates mitogenic activity via several signalling pathways, such as AKT, mitogen-activated protein kinase (MAPK), nuclear factor-kappa B (NF -κB), AP-1 and p53. The exact role that Zn plays in the regulation of apoptosis remains ambiguous. Intracellular free Zn modulates p53 activity and stability, and excess Zn alters the p53 protein structure and down-regulates p53's binding to DNA. Copper (Cu) accumulation causes apoptosis that seems to be mediated by DNA damage and subsequent p53 activation. Cu can also displace Zn from its normal binding site on p53, resulting in abnormal protein folding and disruption of p53 function. In spite of the induction of the tumour suppressor p53, hepatic Cu accumulation significantly increases the risk of cancerous neoplasm both in humans and rats, suggesting that p53 function may be impaired in these cells. It is generally understood that imbalances in Cu and Zn levels may lead to a higher prevalence of p53 mutations. An increased number of p53 mutations have been found in liver samples from Wilson's disease (WD) patients. High levels of the p53 mutation most probably contribute to the pathogenesis of cancer in individuals with WD, but the cause and effect are not clear. The protein p53 also plays a crucial role in the transcriptional regulation of metallothionein, which indicates a novel regulatory role for p53. This review discusses the central role of p53 and the redox-inert metal Zn in the cellular stress responses induced by the redox active biometal Cu.

Zinc transporter 5 and zinc transporter 7 induced by high glucose protects peritoneal mesothelial cells from undergoing apoptosis

Zinc is an essential micronutrient and cytoprotectant involved in many types of apoptosis. The zinc transporter family SLC30A (ZnTs) is an important factor in the regulation of zinc homeostasis; however, its function in apoptosis in peritoneal mesothelial cells (PMCs) remains unknown. This study explores the regulation of zinc transporters and how they play a role in cell survival, particularly in rat peritoneal mesothelial cells (RPMCs), surrounding glucose concentrations, and the molecular mechanism involved. The messenger RNA (mRNA) transcripts were quantitatively measured by real-time polymerase chain reaction for all known nine zinc transport exporters (SLC30A1-8,10), as well as in primary RPMCs and the cells cultured under nonstimulated and HG-stimulated conditions. While many zinc transporters were constitutively expressed, ZnT5 mRNA and ZnT7 mRNA were strongly induced by HG. Overexpression of ZnT5 and ZnT7 respectively resulted in a decrease in the expression of caspace 3, caspace 8, BAX, and AIF and coincided with cell survival in the presence of HG. Inhibition of ZnT5 and ZnT7 expression using considerable siRNA-mediated knockdown of RPMCs was examined and, afterwards, the impact on cell apoptosis was investigated. Increased levels of apoptosis were observed after knockdown of ZnT5 and ZnT7. Furthermore, overexpression of ZnT5 and ZnT7 is accompanied by activation of PI3K/Akt pathway and inhibiting HG-induced apoptosis. This study suggests that the zinc transporting system in RPMCs is influenced by exposure to HG, particularly ZnT5 and ZnT7. This may account for the inhibition of HG-induced RPMC apoptosis and peritoneum injury, likely through targeting PI3K/Akt pathway-mediated cell survival.