Salubrinal protects against tunicamycin and hypoxia induced cardiomyocyte apoptosis via the PERK-eIF2α signaling pathway

Objectives This study examined the protective effect of salubrinal and the mechanism underlying this protection on tunicamycin (TM)- and hypoxia-induced apoptosis in rat cardiomyocytes. Methods Neonatal rat cardiomyocytes were cultured from the ventricles of 1-day-old Wistar rats. Cells were exposed to different concentrations of salubrinal (10, 20, and 40 μmol/L) for 30 minutes followed by TM treatment or hypoxia for 36 hours. Apoptosis was measured by a multiparameter HCS (high content screening) apoptosis assay, TUNEL assay and flow cytometry. The phosphorylation of eukaryotic translation initiation factor 2 subunit alpha (p-eIF2α) and the expression of cleaved caspase-12 were determined by western blotting. C/EBP homologous protein (CHOP) was detected by immunocytochemistry. Results HCS, TUNEL assays and flow cytometry showed that salubrinal protected against apoptosis induced by TM or hypoxia. Western blotting showed that salubrinal protected cardiomyocytes against apoptosis by inducing eIF2α phosphorylation and down-regulating the expression of the endoplasmic reticulum stress-mediated apoptotic proteins, CHOP and cleaved caspase-12. Conclusions Our study suggests that salubrinal protects rat cardiomyocytes against TM- or hypoxia-associated apoptosis via a mechanism involving the inhibition of ER stress-mediated apoptosis.     

Cardiotrophin-1 promotes cardiomyocyte differentiation from mouse induced pluripotent stem cells via JAK2/STAT3/Pim-1 signaling pathway

Background The induced pluripotent stem cell (iPSC) has shown great potential in cellular therapy of myocardial infarction (MI), while its application is hampered by the low efficiency of cardiomyocyte differentiation. The present study was designed to investigate the effects of cardiotrophin-1 (CT-1) on cardiomyocyte differentiation from mouse induced pluripotent stem cells (miPSCs) and the underlying mechanisms involved. Methods The optimal treatment condition for cardiomyocyte differentiation from miPSCs was established with ideal concentration (10 ng/mL) and duration (from day 3 to day 14) of CT-1 administration. Up-regulated expression of cardiac specific genes that accounted for embryonic cardiogenesis was observed by quantitative RT-PCR. Elevated amount of α-myosin heavy chain (α-MHC) and cardiac troponin I (cTn I) positive cells were detected by immunofluorescence staining and flow cytometry analysis in CT-1 group. Results Transmission electron microscopic analysis revealed that cells treated with CT-1 showed better organized sacromeric structure and more mitochondria, which are morphological characteristic of matured cardiomyocytes. Western blot demonstrated that CT-1 promotes cardiomyocyte differentiation from miPSCs partly via JAK2/STAT3/Pim-1 pathway as compared with control group. Conclusions These findings suggested that CT-1 could enhance the cardiomyocyte differentiation as well as the maturation of mouse induced pluripotent stem cell derived cardiomyocytes by regulating JAK2/STAT3/Pim-1signaling pathway.     

Porcine Circovirus 2 Deploys PERK Pathway and GRP78 for Its Enhanced Replication in PK-15 Cells

Porcine circovirus type 2 (PCV2) infection induces autophagy and apoptosis. These cellular responses could be connected with endoplasmic reticulum (ER) stress. It remains unknown if PCV2 induces ER stress and if autophagy or apoptosis is primary to PCV2 infection or secondary responses following ER stress. Here, we demonstrate that PCV2 triggered unfolded protein response (UPR) in PK-15 cells by activating the PERK/eIF2α pathway without concomitant activation of IRE1 or ATF6. Since ATF4 and CHOP were induced later than PERK/eIF2α, it is clear that persistent PCV2 infection could lead to selective activation of PERK via the PERK-eIF2α-ATF4-CHOP axis. Therefore, PERK activation could be part of the pro-apoptotic signaling via induced expression of CHOP by PCV2. Since PERK inhibition by GSK2606414 or RNA silencing or suppression of eIF2α dephosphorylation by salubrinal limited viral replication, we suppose that PCV2 deploys UPR to enhance its replication. Over-expression of GRP78 or treatment with tauroursodeoxycholic acid could enhance viral capsid expression and/or viral titers, indicating that these chaperones, endogenous or exogenous, could help correct folding of viral proteins. Our findings provide the first evidence that ER stress plays a role in the pathogenesis of PCV2 infection probably as part of autophagic and apoptotic responses.     

The human immunodeficiency virus-1 protease inhibitor nelfinavir impairs proteasome activity and inhibits the proliferation of multiple myeloma cells in vitro and in vivo

Background

Multiple myeloma is characterized by the accumulation of tumor plasma cells in the bone marrow. Despite therapeutic improvements brought by proteasome inhibitors such as bortezomib, myeloma remains an incurable disease. In a variety of human cancers, human immunodeficiency virus protease inhibitors (e.g. nelfinavir) effectively inhibit tumor progression, but their impact on myeloma is unknown. We assessed the in vitro and in vivo effects of nelfinavir on multiple myeloma.

Design and Methods

The effects of nelfinavir (1–10 μM) on proteasome activity, proliferation and viability of myeloma cell lines and plasma cells from patients were assessed by measuring PERK, AKT, STAT3 and ERK1/2 phosphorylation and CHOP expression with immunoblotting or flow cytometry. The in vivo effect was assessed in NOD/SCID mice injected with luciferase expressing human myeloma cell lines and treated with nelfinavir at a dose of 75 mg/kg/day. Tumor progression was evaluated using a bioluminescent system.

Results

Nelfinavir inhibited 26S chymotrypsin-like proteasome activity, impaired proliferation and triggered apoptosis of the myeloma cell lines and fresh plasma cells. It activated the pro-apoptotic unfolded protein response pathway by inducing PERK phosphorylation and CHOP expression. Cell death triggered by nelfinavir treatment correlated with decreased phosphorylation of AKT, STAT3 and ERK1/2. Nelfinavir enhanced the anti-proliferative activity of bortezomib, dexamethasone and histone deacetylase inhibitors and delayed tumor growth in a myeloma mouse model.

Conclusions

These results suggest that nelfinavir, used at a pharmacological dosage, alone or in combination, may be useful in the treatment of myeloma. Our data provide a preclinical basis for clinical trials using nelfinavir in patients with myeloma.     

The antiapoptotic effect of mesenchymal stem cell transplantation on ischemic myocardium is enhanced by anoxic preconditioning

BACKGROUND:

Cardiomyocyte apoptosis takes place at an early stage after myocardial infarction (MI). Therapy with mesenchymal stem cells (MSCs) is reported to reduce apoptosis.

OBJECTIVES:

To determine whether anoxic preconditioning (AP) could enhance the antiapoptotic effect of MSCs.

METHODS:

Cultured cardiomyocytes were treated with Dulbecco’s modified Eagle’s medium (as a control), MSCs or AP-MSCs, and were exposed to hypoxia/reoxygenation. Apoptotic cardiomyocytes were stained with Annexin V fluorescein isothiocyanate (BioVision, USA), visualized by fluorescence microscopy and analyzed by flow cytometry. In vivo, MI was produced in Sprague-Dawley rats by permanent ligation of the left anterior descending coronary artery and the left ventricles were randomly injected with Dulbecco’s modified Eagle’s medium, MSCs or AP-MSCs one week after MI. The cardiomyocyte apoptotic rate in peri-infarcted areas was assessed by terminal deoxynucleotidyltransferase-mediated 2′-deoxyuridine 5′-triphosphate nick end labelling assay one week after transplantation. Cardiac function was assessed by echocardiography four weeks after transplantation. Infarct size was measured by hematoxylin and eosin staining one and four weeks after transplantation. The expression of Bcl-2, Bax protein and cleaved cysteine-aspartic acid protease-3 was analyzed by Western blot techniques.

RESULTS:

Cardiomyocyte apoptosis (both induced by hypoxia/reoxygenation and MI) was significantly reduced by treating with MSCs and AP-MSCs, the Bcl-2 to Bax protein ratio was increased and cleaved cysteine-aspartic acid protease-3 was decreased. AP-MSCs were superior to MSCs.

CONCLUSIONS:

MSCs protected the infarcted heart by preventing cardiomyocyte apoptosis and AP enhanced the cardioprotective effects of MSCs.     

Effect of a low dose of proteasome inhibitor on cell death and gene expression in neonatal rat cardiomyocyte cultures exposed to anoxia-reoxygenation

BACKGROUND:

Recent data suggest that low concentrations of proteasome inhibitors (PIs) are cytoprotective in models of ischemia-reperfusion injury, but the underlying mechanisms of this effect still remain unclear.

AIM:

To investigate the effect of 100 nM of clasto-lactacystin β-lactone on cell death and gene expression in neonatal rat cardiomyocytes exposed to anoxia-reoxygenation.

METHODS:

Fluorescent microscopy and real-time polymerase chain reaction were used to detect different types of cell death and gene expression, respectively, in neonatal rat cardiomyocyte cultures exposed to anoxia-reoxygenation.

RESULTS:

It was shown that a low dose of clasto-lactacystin β-lactone protected the cells against anoxia-reoxygenation injury by a reduction in the number of necrotic and apoptotic cells. The number of autophagic cells was greatly increased by proteasomal inhibition. The PI increased the heat shock protein 70 messenger RNA expression twofold and slightly reduced the expression of heat shock protein 90 gene. The expression of the FK506 binding protein 12-rapamycin associated protein gene was increased 1.57-fold on PI application. The B-cell lymphoma 2 gene expression was unaffected by the use of clasto-lactacystin β-lactone in low dose.

CONCLUSION:

Although PIs are injurious, they may be cardioprotective in low doses; ie, they do not result in cell death. Moreover, PIs initiate the protective mechanisms that prevent cell damage by changing the expression of several genes.     

The role of sirtuin 2 activation by nicotinamide phosphoribosyltransferase in the aberrant proliferation and survival of myeloid leukemia cells

Background

Inhibitors of nicotinamide phosphoribosyltransferase have recently been validated as therapeutic targets in leukemia, but the mechanism of leukemogenic transformation downstream of this enzyme is unclear.

Design and Methods

Here, we evaluated whether nicotinamide phosphoribosyltransferase’s effects on aberrant proliferation and survival of myeloid leukemic cells are dependent on sirtuin and delineated the downstream signaling pathways operating during this process.

Results

We identified significant upregulation of sirtuin 2 and nicotinamide phosphoribosyltransferase levels in primary acute myeloid leukemia blasts compared to in hematopoietic progenitor cells from healthy individuals. Importantly, specific inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 significantly reduced proliferation and induced apoptosis in human acute myeloid leukemia cell lines and primary blasts. Intriguingly, we found that protein kinase B/AKT could be deacetylated by nicotinamide phosphoribosyltransferase and sirtuin 2. The anti-leukemic effects of the inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 were accompanied by acetylation of protein kinase B/AKT with subsequent inhibition by dephosphorylation. This leads to activation of glycogen synthase kinase-3 β via diminished phosphorylation and, ultimately, inactivation of β-catenin by phosphorylation.

Conclusions

Our results provide strong evidence that nicotinamide phosphoribosyltransferase and sirtuin 2 participate in the aberrant proliferation and survival of leukemic cells, and suggest that the protein kinase B/AKT/ glycogen synthase kinase-3 β/β-catenin pathway is a target for inhibition of nicotinamide phosphoribosyltransferase or sirtuin 2 and, thereby, leukemia cell proliferation.     

Protective effect of electroacupuncture at the Neiguan point in a rabbit model of myocardial ischemia-reperfusion injury

OBJECTIVES:

To investigate possible cardioprotective mechanisms of electroacupuncture (EA) at the Neiguan point and at the Lieque point in the presence of myocardial ischemia-reperfusion injury (MIRI).

METHODS:

The changes in ventricular tissue Bax and Bcl-2 protein expression, malondialdehyde (MDA) content and glutathione peroxidase (GSH-PX) activity were examined, as well as beta-endorphin (β-EP) content in a rabbit model of MIRI. Four randomized groups were studied: sham, untreated MIRI, MIRI followed by EA at the Neiguan point, and MIRI followed by EA at the Lieque point. The MIRI model involved ligating the left anterior descending coronary artery for 30 min followed by a 60 min postischemia reperfusion period.

RESULTS:

EA at the Neiguan point dramatically decreased the number of apoptotic cells and the content of β-EP and MDA, and inhibited Bax protein expression while enhancing Bcl-2 expression and GSH-PX activity. Furthermore, EA enhanced Bcl-2 expression and GSH-PX activity. Lesser effects were elicited by EA at the Lieque point.

CONCLUSIONS:

The cardioprotective effects of applying EA at the Neiguan point on MIRI include reducing apoptosis, regulating apoptosis-controlling genes, and decreasing myocardial MDA and β-EP while enhancing GSH-PX activity.     

Asiatic acid inhibits cardiac hypertrophy by blocking interleukin-1β-activated nuclear factor-κB signaling in vitro and in vivo

Background

Activated interleukin (IL)-1β signaling pathway is closely associated with pathological cardiac hypertrophy. This study investigated whether asiatic acid (AA) could inhibit IL-1β-related hypertrophic signaling, and thus suppressing the development of cardiac hypertrophy.

Methods

Transverse aortic constriction (TAC) induced cardiac hypertrophy in C57BL/6 mice and cultured neonatal cardiac myocytes stimulated with IL-1β were used to evaluate the role of AA in cardiac hypertrophy. The expression of atrial natriuretic peptide (ANP) was evaluated by quantitative polymerase chain reaction (qPCR) and the nuclear factor (NF)-κB binding activity was measured by electrophoretic mobility shift assays (EMSA).

Results

AA pretreatment significantly attenuated the IL-1β-induced hypertrophic response of cardiomyocytes as reflected by reduction in the cardiomyocyte surface area and the inhibition of ANP mRNA expression. The protective effect of AA on IL-1β-stimulated cardiomyocytes was associated with the reduction of NF-κB binding activity. In addition, AA prevented TAC-induced cardiac hypertrophy in vivo. It was found that AA markedly reduced the excessive expression of IL-1β and ANP, and inhibited the activation of NF-κB in the hypertrophic myocardium.

Conclusions

Our data suggest that AA may be a novel therapeutic agent for cardiac hypertrophy. The inhibition of IL-1β-activated NF-κB signaling may be the mechanism through which AA prevents cardiac hypertrophy.     

AMD3100 disrupts the cross-talk between chronic lymphocytic leukemia cells and a mesenchymal stromal or nurse-like cell-based microenvironment: pre-clinical evidence for its association with chronic lymphocytic leukemia treatments

Background

Interactions with the microenvironment, such as bone marrow mesenchymal stromal cells and nurse-like cells, protect chronic lymphocytic leukemia cells from spontaneous and drug-induced apoptosis. This protection is partially mediated by the chemokine SDF-1α (CXCL12) and its receptor CXCR4 (CD184) present on the chronic lymphocytic leukemia cell surface.

Design and Methods

Here, we investigated the ability of AMD3100, a CXCR4 antagonist, to sensitize chronic lymphocytic leukemia cells to chemotherapy in a chronic lymphocytic leukemia/mesenchymal stromal cell based or nurse-like cell based microenvironment co-culture model.

Results

AMD3100 decreased CXCR4 expression signal (n=15, P=0.0078) and inhibited actin polymerization/migration in response to SDF-1α (n=8, P<0.01) and pseudoemperipolesis (n=10, P=0.0010), suggesting that AMD3100 interferes with chronic lymphocytic leukemia cell trafficking. AMD3100 did not have a direct effect on apoptosis when chronic lymphocytic leukemia cells were cultured alone (n=10, P=0.8812). However, when they were cultured with SDF-1α, mesenchymal stromal cells or nurse-like cells (protecting them from apoptosis, P<0.001), chronic lymphocytic leukemia cell pre-treatment with AMD3100 significantly inhibited these protective effects (n=8, P<0.01) and decreased the expression of the anti-apoptotic proteins MCL-1 and FLIP. Furthermore, combining AMD3100 with various drugs (fludarabine, cladribine, valproïc acid, bortezomib, flavopiridol, methylprednisolone) in our mesenchymal stromal cell co-culture model enhanced drug-induced apoptosis (n=8, P<0.05) indicating that AMD3100 could mobilize chronic lymphocytic leukemia cells away from their protective microenvironment, making them more accessible to conventional therapies.

Conclusions

Taken together, these data demonstrate that interfering with the SDF-1α/CXCR4 axis by using AMD3100 inhibited chronic lymphocytic leukemia cell trafficking and microenvironment-mediated protective effects. Combining AMD3100 with other drugs may, therefore, represent a promising therapeutic approach to kill chronic lymphocytic leukemia cells.     

ER stress in rodent islets of Langerhans is concomitant with obesity and β-cell compensation but not with β-cell dysfunction and diabetes

Objective:

The objective of this study was to determine whether ER stress correlates with β-cell dysfunction in obesity-associated diabetes.

Methods:

Quantitative RT-PCR and western blot analysis were used to investigate changes in the expression of markers of ER stress, the unfolded protein response (UPR) and β-cell function in islets isolated from (1) non-diabetic Zucker obese (ZO) and obese female Zucker diabetic fatty (fZDF) rats compared with their lean littermates and from (2) high-fat-diet-fed fZDF rats (HF-fZDF), to induce diabetes, compared with age-matched non-diabetic obese fZDF rats.

Results:

Markers of an adaptive ER stress/UPR and β-cell function are elevated in islets isolated from ZO and fZDF rats compared with their lean littermates. In islets isolated from HF-fZDF rats, there was no significant change in the expression of markers of ER stress compared with age matched, obese, non-diabetic fZDF rats.

Conclusions:

These results provide evidence that obesity-induced activation of the UPR is an adaptive response for increasing the ER folding capacity to meet the increased demand for insulin. As ER stress is not exacerbated in high-fat-diet-induced diabetes, we suggest that failure of the islet to mount an effective adaptive UPR in response to an additional increase in insulin demand, rather than chronic ER stress, may ultimately lead to β-cell failure and hence diabetes.     

Ox-LDL induces endothelial cell apoptosis via the LOX-1-dependent endoplasmic reticulum stress pathway

Objective

To investigate the effect of lectin-like ox-LDL receptor-1 (LOX-1) on oxidized low-density lipoprotein (ox-LDL)-induced apoptosis and the involvement of the endoplasmic reticulum (ER) stress response pathway.

Methods and results

Human umbilical vein endothelial cells were treated with 50, 100, or 200 μg/ml ox-LDL and cultured for 12, 24, or 48 h for concentration- and time-dependent studies. Cells were transfected with LOX-1 or Nox-4 shRNAs, and target proteins were inhibited with the corresponding antibodies for mechanistic studies. Active proteins and mRNAs were analyzed by Western blotting and RT-PCR, respectively. Cell apoptosis was analyzed by Annexin and Hoechst staining assays. Ox-LDL induced both apoptosis and protein expression of LOX-1 and Nox-4 through activation of ER stress sensors IRE1 and PERK, and nuclear translocation of ATF6 and their subsequent pathways were indicated by JNK, eukaryotic initiation factor 2 phosphorylation, XBP-1, and chaperone GRP78 expression; up-regulation of proapoptotic proteins CHOP and Bcl-2; and caspase-12 activity. LOX-1 gene silencing and treatment with an anti-LOX-1 antibody attenuated the effects of ox-LDL. Pretreatment with irestatin 9389, salubrinal, or AEBSF also blocked ox-LDL-induced expression of CHOP and Bcl-2 and activation of caspase-12 activity, leading to an attenuation of endothelial cell apoptosis. Furthermore, Nox-4 siRNA attenuated the up-regulated expression of GRP78, PERK, IRE1, and XBP-1 to reduce ox-LDL-induced endothelial cell apoptosis.

Conclusions

LOX-1 plays a critical role in ox-LDL-induced endothelial cell apoptosis via the ER stress pathway.     

��-tocotrienol protects mouse and human hematopoietic progenitors from ��-irradiation through extracellular signal-regulated kinase/mammalian target of rapamycin signaling

Background

Exposure to γ-radiation causes rapid hematopoietic cell apoptosis and bone marrow suppression. However, there are no approved radiation countermeasures for the acute radiation syndrome. In this study, we demonstrated that natural δ-tocotrienol, one of the isomers of vitamin E, significantly enhanced survival in total body lethally irradiated mice. We explored the effects and mechanisms of δ-tocotrienol on hematopoietic progenitor cell survival after γ-irradiation in both in vivo and in vitro experiments.

Design and Methods

CD2F1 mice and human hematopoietic progenitor CD34⁺ cells were treated with δ-tocotrienol or vehicle control 24 h before or 6 h after γ-irradiation. Effects of δ-tocotrienol on hematopoietic progenitor cell survival and regeneration were evaluated by clonogenicity studies, flow cytometry, and bone marrow histochemical staining. δ-tocotrienol and γ-irradiation-induced signal regulatory activities were assessed by immunofluorescence staining, immunoblotting and short-interfering RNA assay.

Results

δ-tocotrienol displayed significant radioprotective effects. A single injection of δ-tocotrienol protected 100% of CD2F1 mice from total body irradiation-induced death as measured by 30-day post-irradiation survival. δ-tocotrienol increased cell survival, and regeneration of hematopoietic microfoci and lineage⁻/Sca-1⁺/ckit⁺ stem and progenitor cells in irradiated mouse bone marrow, and protected human CD34⁺ cells from radiation-induced damage. δ-tocotrienol activated extracellular signal-related kinase 1/2 phosphorylation and significantly inhibited formation of DNA-damage marker γ-H2AX foci. In addition, δ-tocotrienol up-regulated mammalian target of rapamycin and phosphorylation of its downstream effector 4EBP-1. These alterations were associated with activation of mRNA translation regulator eIF4E and ribosomal protein S6, which is responsible for cell survival and growth. Inhibition of extracellular signal-related kinase 1/2 expression by short interfering RNA abrogated δ-tocotrienol-induced mammalian target of rapamycin phosphorylation and clonogenicity, and increased γ-H2AX foci formation in irradiated CD34⁺ cells.

Conclusions

Our data indicate that δ-tocotrienol protects mouse bone marrow and human CD34⁺ cells from radiation-induced damage through extracellular signal-related kinase activation-associated mammalian target of rapamycin survival pathways.     

Rosuvastatin inhibits the smooth muscle cell proliferation by targeting TNFα mediated Rho kinase pathway

Objective To investigate whether Tumor Necrosis Factor-alpha (TNFα) is capable of activating Rho kinase pathway which leads to smooth muscle cell proliferation and the intervention function of Rosuvastatin, and clarify the mechanism and intervention manner of anti-atherosclerosis by Rosuvastatin. Methods Wistar neonate rat smooth muscle cells were cultured, and the activity of cell proliferation was determined by methyl thiazolyl tetrazolium (MTT). The expression of Rho kinase genes after the stimulation of TNFα was evaluated by RT-PCR. Western blot method was used to measure the protein expression of proliferating cell nuclear antigen (PCNA) after TNFα stimulation and Rosuvastatin intervention in smooth muscle cell. Results The TNFα stimulation significantly enhanced the expression of Rho kinase and increased the expression of PCNA protein in smooth muscle cells (P < 0.05). These effects were positively correlated with prolonged treatment whereas additional Rosuvastatin administration inhibited the above-mentioned effects (P < 0.05). Conclusions The activation of TNFα mediated Rho kinase signaling pathway can significantly promote smooth muscle cell proliferation, and Rosuvastatin can not only inhibit this pathway but also the induced proliferation.     

消癌解毒方通过内质网应激诱导肝癌HepG2细胞凋亡的研究

[目的]探讨内质网应激在消癌解毒方在人肝癌HepG2细胞凋亡中的作用。[方法]CCK-8法检测不同浓度的消癌解毒方处理HepG2细胞12、24、48 h后细胞的增殖情况;采用流式细胞术检测细胞消癌解毒方处理HepG2细胞24 h凋亡情况;应用qRT-PCR检测内质网应激上游分子标记GRP78、PERK、ATF-6、IRE-1的mRNA水平;采用Western blot方法分析消癌解毒方对PERK、ATF4、CHOP和TRB3蛋白的表达情况;并用CCK-8法检测内质网抑制剂4-苯基丁酸(4-PBA)对HepG2细胞凋亡率的影响。[结果]消癌解毒方抑制HepG2细胞的增殖,并且这种效应呈现时间和浓度依赖;ATF-6和IRE-1 mRNA水平无明显变化,GRP78和PERK mRNA水平较阴性对照组均显著增加;消癌解毒方可上调内质网应激通路的标志蛋白质PERK、ATF4、CHOP水平,增加下游TRB3蛋白的表达。4-PBA与消癌解毒方联合作用组的细胞凋亡率显著减少。[结论]消癌解毒方通过内质网应激诱导人肝癌HepG2细胞的凋亡,其可能是通过PERK通路上调内质网应激相关凋亡蛋白CHOP的表达。     

Low-molecular-weight proteins as prognostic markers in idiopathic membranous nephropathy

Summary

Background

Accurate prediction of prognosis in idiopathic membranous nephropathy (iMN) allows restriction of immunosuppressive therapy to patients at high risk for ESRD. Here we re-evaluate urinary low-molecular-weight proteins as prognostic markers and explore causes of misclassification.

Design, setting, participants, & measurements

In a cohort of 129 patients with serum creatinine concentration <135 μmol/L and proteinuria ≥3.0 g/10 mmol, urinary α1- (uα1m) and β2-microglobulin (uβ2m) excretion rate was determined. Urinary α1m and uβ2m-creatinine ratio was also obtained. We defined progression as a rise in serum creatinine ≥50% or ≥25% and an absolute level ≥135 μmol/L.

Results

Median survival time was 25 months, and 47% of patients showed progression. The area under the receiver operating characteristic curve for uβ2m was 0.81 (95% CI: 0.73 to 0.89). Using a threshold value of 1.0 μg/min, sensitivity and specificity were 73% and 75%, respectively. Similar accuracy was observed for the uβ2m-creatinine ratio with sensitivity and specificity of 75% and 73%, respectively, at a threshold of 1.0 μg/10 mmol creatinine. Similar accuracy was found for uα1m and uα1m-creatinine ratio. Blood Pressure and cholesterol contributed to misclassification. Repeated measurements improved accuracy in patients with persistent proteinuria: the positive predictive value of uβ2m increased from 72% to 89% and the negative predictive value from 76% to 100%.

Conclusions

Urinary excretion of uα2m and uβ2m predict prognosis in iMN. A spot urine sample can be used instead of a timed sample. A repeated measurement after 6 to 12 months increases prognostic accuracy.