Accumulating evidence has revealed that brain iron concentrations increase with aging, and the choroid plexus (CP) may be at the basis of iron-mediated toxicity and the increase in inflammation and oxidative stress that occurs with aging. The mechanism involves not only hepcidin, the key hormone in iron metabolism, but also iron-related proteins and signaling-transduction molecules, such as IL-6 and signal transducer and activator of transcription 3 (Stat3). The aim of the present study was to investigate the correlation between the IL-6/Stat3 signaling pathway and hepcidin at the CP in normal aging. Quantitative real time PCR and Western blot were used to determine the alterations in specific mRNA and corresponding protein changes at the CP at ages of 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 and 36 months in Brown-Norway/Fischer (B-N/F) rats. The results demonstrated that hepcidin mRNA level at the CP kept stable in young rats (from 3 to 18 months), and increased with aging (from 21 to 36 months). The alterations of IL-6/p-Stat3 mRNA and protein expressions in normal aging were in accordance with that of hepcidin mRNA. Our data suggest that IL-6 may regulate hepcidin expression at the CP, upon interaction with the cognate cellular receptor, and through the Stat3 signaling transduction pathway.
Aging ; physiology ; Animals ; Choroid Plexus ; metabolism ; Hepcidins ; physiology ; Interleukin-6 ; physiology ; Iron ; metabolism ; RNA, Messenger ; Rats ; Rats, Inbred F344 ; STAT3 Transcription Factor ; physiology ; Signal Transduction

OBJECTIVETo study the role and mechanisms of STAT3 signaling pathway in hypoxic-ischemic brain damage (HIBD) of neonatal rats.

METHODSEighty 7-day-old Sprague-Dawley rats were randomly divided into two groups: HI and sham-operated (n=40 each). The rats in the HI group were subjected to right carotid artery ligation and subsequent hypoxia exposure (8% O2) for 2.5 hours, and the rats in the sham-operated group underwent the right carotid artery dissection without subsequent ligation or hypoxia treatment. Brain tissue samples were collected at 4, 6, 8, 12 and 24 hours after operation and hypoxic exposure. Immunohistochemistry and Western blot were used to detect the expression of STAT3, phosphorylated STAT3 (p-STAT3) and vascular endothelial growth factor (VEGF) proteins. TUNEL staining was used to detect apoptotic cells.

RESULTSNo significant difference in STAT3 expression was observed at all time points between the HI and sham-operated groups (P>0.05). Compared with the sham-operated group, the expression of p-STAT3 protein in the HI group was significantly upregulated at 4, 6, 8, 12 hours after operation and hypoxic exposure, and peaked at 6 hours (P<0.01). The VEGF expression in the HI group was higher than that in the sham-operated group at all time points, which peaked at 8 hours (P<0.05). TUNEL staining showed that the apoptotic cells increased significantly in a time-dependent manner compared with the sham-operated group (P<0.01).

CONCLUSIONSHI may lead to phosphorylation of STAT3 which probably induces the VEGF expression in the brain of neonatal rats. The activated STAT3 signaling pathway may be involved in the apoptosis regulation of nerve cells, and related to apoptosis inhibition of nerve cells.

Animals ; Animals, Newborn ; Female ; Hypoxia-Ischemia, Brain ; metabolism ; Male ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; physiology ; Signal Transduction ; physiology ; Vascular Endothelial Growth Factor A ; analysis

BACKGROUNDMesenchymal stem cells (MSCs) transplantation has been proven to have therapeutic potential for acute liver failure (ALF). However, the mechanism remains controversial. Recently, modulation of inflammation by MSCs has been regarded as a crucial mechanism. The aim of the present study was to explore the soluble cytokines secreted by MSCs and their therapeutic effects in ALF.

METHODSMSCs isolated from Sprague-Dawley rats were identified by fluorescence-activated cell sorting analysis. Conditioned medium derived from MSCs (MSCs-CM) was collected and analyzed by a cytokine microarray. MSCs and MSCs-CM were transplanted into rats with D-galactosamine-induced ALF. Liver function, survival rate, histology, and inflammatory factors were determined. Exogenous recombinant rat interleukin (IL)-10, anti-rat IL-10 antibody, and AG490 (signal transducer and activator of transcription 3 [STAT3] signaling pathway inhibitor) were administered to explore the therapeutic mechanism of MSCs-CM. Statistical analysis was performed with SPSS version 19.0, and all data were analyzed by the independent-sample t-test.

RESULTSThere are statistical differences of the survival curve between ALF+MSCs group and ALF+Dulbecco's modified Eagle's medium (DMEM) group, as well as ALF+MSCs-CM group and ALF+DMEM group (all P < 0.05). Serum alanine aminotransferase (ALT) level in the ALF+MSCs and ALF+MSCs-CM groups was lower than that in the ALF+DMEM group (865.53±52.80 vs. 1709.75±372.12 U/L and 964.72±414.59 vs. 1709.75±372.12 U/L, respectively, all P < 0.05); meanwhile, serum aspartate aminotransferase (AST) level in the ALF+MSCs and ALF+MSCs-CM groups was lower than that in the ALF+DMEM group (2440.83±511.94 vs. 4234.35±807.30 U/L and 2739.83±587.33 vs. 4234.35±807.30 U/L, respectively, all P < 0.05). Furthermore, MSCs or MSCs-CM treatment significantly reduced serum interferon-γ (IFN-γ), IL-1β, IL-6 levels and increased serum IL-10 level compared with DMEM (all P < 0.05). Proteome profile analysis of MSCs-CM indicated the presence of anti-inflammatory factors and IL-10 was the most distinct. Blocking of IL-10 confirmed the therapeutic significance of this cytokine. Phosphorylated STAT3 was upregulated after IL-10 infusion and inhibition of STAT3 by AG490 reversed the therapeutic effect of IL-10.

CONCLUSIONSThe factors released by MSCs, especially IL-10, have the potential for therapeutic recovery of ALF, and the STAT3 signaling pathway may mediate the anti-inflammatory effect of IL-10.

Animals ; Interleukin-10 ; physiology ; Liver ; pathology ; Liver Failure, Acute ; pathology ; therapy ; Male ; Mesenchymal Stem Cell Transplantation ; Rats ; Rats, Sprague-Dawley ; STAT3 Transcription Factor ; physiology ; Signal Transduction ; physiology

Combined radiation-wound injury (CRWI) is characterized by blood vessel damage and pro-inflammatory cytokine deficiency. Studies have identified that the direct application of leptin plays a significant role in angiogenesis and inflammation. We established a sustained and stable leptin expression system to study the mechanism. A lentivirus method was employed to explore the angiogenic potential and peripheral inflammation of irradiated human umbilical vein endothelial cells (HUVECs). Leptin was transfected into human placenta-derived mesenchymal stem cells (HPMSCs) with lentiviral vectors. HUVECs were irradiated by X-ray at a single dose of 20 Gy. Transwell migration assay was performed to assess the migration of irradiated HUVECs. Based on the Transwell systems, co-culture systems of HPMSCs and irradiated HUVECs were established. Cell proliferation was measured by cell counting kit-8 (CCK-8) assay. The secretion of pro-inflammatory cytokines (human granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin (IL)-1α, IL-6, and IL-8) was detected by enzyme-linked immunosorbent assay (ELISA). The expression of pro-angiogenic factors (vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF)) mRNA was detected by real-time quantitative polymerase chain reaction (RT-qPCR) assay. Relevant molecules of the nuclear factor-κB (NF-κB) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways were detected by western blot assay. Results showed that leptin-modified HPMSCs (HPMSCs/ leptin) exhibited better cell proliferation, migration, and angiogenic potential (expressed more VEGF and bFGF). In both the single HPMSCs/leptin and the co-culture systems of HPMSCs/leptin and irradiated HUVECs, the increased secretion of pro-inflammatory cytokines (human GM-CSF, IL-1α, and IL-6) was associated with the interaction of the NF-κB and JAK/STAT signaling pathways. We conclude that HPMSCs/leptin could promote angiogenic potential and peripheral inflammation of HUVECs after X-ray radiation.
Cell Proliferation ; Cells, Cultured ; Cytokines/biosynthesis* ; Female ; Human Umbilical Vein Endothelial Cells/radiation effects* ; Humans ; Inflammation/etiology* ; Leptin/pharmacology* ; Mesenchymal Stem Cells/physiology* ; Neovascularization, Physiologic/physiology* ; Placenta/cytology* ; Pregnancy ; STAT3 Transcription Factor/genetics* ; Transcription Factor RelA/genetics* ; X-Rays

Animals ; Carcinoma, Non-Small-Cell Lung ; metabolism ; Humans ; Janus Kinases ; metabolism ; Lung Neoplasms ; metabolism ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; genetics ; physiology

This study was aimed to investigate the changes of the hypothalamic-pituitary-adrenal axis (HPAA) activity and the cytokines system in the hypothalamus of the depressive rats which were exposed to chronic unpredictable mild stressors (CUMS) after middle cerebral artery occlusion (MCAO). By means of qRT-PCR, ELISA and Western blot, mRNA and/or protein expressions of corticotropin releasing factor (CRF), tumor necrosis factors-α (TNF-α), suppressor of cytokines signaling 3 (SOCS3), phosphorylation of signal transducers and activators of transcription 3 (pSTAT3) were measured in the hypothalamus of rats. The results showed that, compared with control group, CUMS+MCAO group exhibited increased mRNA levels of CRF, TNF-α, SOCS3, as well as up-regulated CRF, TNF-α, SOCS3 and pSTAT3 protein expressions. Furthermore, there were correlations between CRF and TNF-α, TNF-α and SOCS3, SOCS3 and pSTAT3, respectively. These observations indicated the CRF system was activated in the post stroke depression (PSD) status. The TNF-α and its signaling pathway, STAT3/SOCS3, were up-regulated in mRNA and protein levels. In conclusion, this study presents the evidence which supports the hypothesis of signaling cross-talk between the CRF system and TNF-α signaling pathway after ischemic stroke and CUMS.
Animals ; Hypothalamo-Hypophyseal System ; physiology ; Hypothalamus ; physiology ; Infarction, Middle Cerebral Artery ; Phosphorylation ; Pituitary-Adrenal System ; physiology ; Rats ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; Suppressor of Cytokine Signaling 3 Protein ; Suppressor of Cytokine Signaling Proteins ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism ; Up-Regulation

Mouse embryonic stem cells (ES cells) are pluripotent in that they can give rise to almost all the cell types in vitro and in vivo. Also, they can sustain self-renewal in vitro owing to symmetrical mitosis, i.e., only the cell number increases while the daughter cells remain pluripotent. Self-renewal and pluripotency of ES cells are under stringent regulation of several signaling pathways. Activation of either JAK-STAT3 or PI3K, the downstream cascade of gp130, can maintain the self-renewal of ES cells, while phosphorylation of another gp130-related branch, SHP2-Ras-ERK, drives the differentiation. BMP2/4-mediated signaling is capable of suppressing the differentiation of ES cells in collaboration with activated JAK-STAT3 under serum free culture conditions. Other signaling such as Wnt also contributes to the self-renewal of ES cells. Generally, the network, which is composed of various signaling pathways, modulates the self-renewal and differentiation of mouse ES cells precisely. This review focuses on the role of gp130 in proliferation of mouse ES cells including inhibitory effect of JAK-STAT3 pathway activation on differentiation of mouse ES cells, maintenance effect of PI3K pathway activation on self-renewal of ES cells, promotive effect of SHP-2-Ras-ERK pathway activation on differentiation of ES cells, and influence of other signaling pathways on self-renewal of mouse ES cells, including maintenance effect of BMP combination with LIF under serum free culture conditions on self-renewal of ES cells and promotive effect of Wnt pathway activation on self-renewal of ES cells.
Animals ; Cell Differentiation ; physiology ; Cell Proliferation ; Cell Survival ; Cells, Cultured ; Cytokine Receptor gp130 ; metabolism ; Embryonic Stem Cells ; cytology ; physiology ; Janus Kinase 1 ; metabolism ; Leukemia Inhibitory Factor ; metabolism ; Mice ; STAT3 Transcription Factor ; metabolism ; Signal Transduction ; physiology

BACKGROUNDAutoantibodies against angiotensin AT1 receptor have been discovered in patients with preeclampsia or malignant hypertension. Some studies have demonstrated that the autoantibodies are involved in the immunopathogenesis of hypertension and have an agonist effect similar to angiotensin II.

METHODSAutoantibodies against AT1 receptor were purified from sera of patients with primary hypertension by affinity chromatography. Proliferation of cultured rat vascular smooth muscle cells was detected by bromodeoxyuridine incorporation and activation of signalling molecules detected by Western blotting and electrophoretic mobility shift assay.

RESULTSThe AT1-RAb caused a significant proliferation similar to the Ang II during first 24 hours. The levels of nuclear factor-kappaB (NF-kappaB), phosphorylated JAK2, phosphorylated STAT1 (pSTAT1) and phosphorylated STAT3 (pSTAT3) molecules were increased in response to the autoantibodies. In contrast, the activations of NF-kappaB and JAK-STAT were blocked by losartan, pyrrolidinedithiocarbamate (a specific inhibitor of NF-kappaB) and AG490 (a specific inhibitor of the JAK2 tyrosine kinase). The expressions of NF-kappaB, pSTAT1 and pSTAT3 reached peak levels at different times. Moreover, the relative densities of electrophoretic bands showed that activation of pSTAT3 was more significant than STAT1 induced by AT1-RAb.

CONCLUSIONSThese results suggest that the autoantibodies against AT1 receptor have an agonist effect similar to Ang II in proliferation of VSMCs and the NF-kappaB and JAK-STAT proteins play essential roles. The effect is different from Ang II in that STAT3 is the main downstream activating molecule in JAK-STAT signalling pathway.

Animals ; Autoantibodies ; immunology ; Cell Proliferation ; Humans ; Hypertension ; immunology ; Janus Kinase 2 ; physiology ; Muscle, Smooth, Vascular ; cytology ; NF-kappa B ; physiology ; Rats ; Rats, Wistar ; Receptor, Angiotensin, Type 1 ; immunology ; STAT3 Transcription Factor ; physiology ; Signal Transduction ; physiology

OBJECTIVELipoxin A(4) is formed by the metabolism of arachidonic acid. Anti-inflammatory and anti-proliferative effect of lipoxin A(4) has been shown in many human diseases. Recently, as a novel high affinity receptor for ligand lipoxin A(4), Lipoxin A(4) receptor-like protein (LRLP) has been identified. Currently close attention is paid to the important contribution of connective tissue growth factor (CTGF) in lung fibrosis. The purpose of the study was to transfect LRLP gene into human lung fibroblasts and investigate the mechanism of its enhancing antagonistic effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by connective tissue growth factor.

METHODSEukaryocytic expression vector pEGFP/LRLP which contained LRLP and green fluorescence protein fusion gene (GFP) was constructed and transfected into human lung fibroblasts (HLF). After selecting with G418, HLF/LRLP cell clone which stably expressed LRLP/GFP fusion protein was isolated and characterized by the laser scanning confocal microscope. Cultured HLF and HLF/LRLP were stimulated for 24 h with CTGF (1 microg/ml) in the presence and absence of pretreatment of Lipoxin A(4) (10.0 nmol/L) for 30 min. Inhibition of cell proliferation was determined by MTT assay. Cell cycle analysis was performed by flow cytometry. Western blot was used to detect the expression of cyclin D(1) protein. Electrophoretic mobility shift assay (EMSA) was employed to detect the DNA binding activity of STAT(3).

RESULTS(1) HLF/LRLP cell clone which stably expressed LRLP and GFP fusion protein was successfully obtained. (2) Proliferation of HLF and HLF/LRLP was induced by 1 microg/ml CTGF. Pretreatment with 10 nm Lipoxin A(4) inhibited the proliferation of HLF and HLF/LRLP. And the inhibitory rate of HLF/LRLP was significantly higher than that of HLF [(54.1 +/- 4.2)%, (21.2 +/- 3.7)%, P < 0.05]. (3) The flow cytometry analysis showed that compared with HLF, more HLF/LRLP were arrested at G(0)/G(1) phase in the presence of pretreatment of Lipoxin A(4). [(76.3 +/- 3.5)%, (60.8 +/- 2.0)%, P < 0.05]. (4) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of cyclin D(1) protein expression in HLF and HLF/LRLP. And its antagonistic effect on HLR/LRLP was stronger than that on HLF (P < 0.05). (5) Ten nmol/L Lipoxin A(4) antagonized CTGF induced increase of STAT(3) DNA binding activity, and its antagonistic effect on HLF/LRLP was more powerful than that on HLF (P < 0.05).

CONCLUSIONSTransfection of Lipoxin A(4) receptor-like protein gene enhanced the inhibitory effect of Lipoxin A(4) on human lung fibroblasts proliferation induced by CTGF. Its mechanism might be related to regulation of cyclin D(1) protein expression and STAT(3) DNA binding activity.

Connective Tissue Growth Factor ; antagonists & inhibitors ; Cyclin D1 ; analysis ; DNA ; metabolism ; Fibroblasts ; cytology ; drug effects ; Humans ; Lipoxins ; pharmacology ; Lung ; cytology ; drug effects ; Receptors, Formyl Peptide ; genetics ; physiology ; Receptors, Lipoxin ; genetics ; physiology ; STAT3 Transcription Factor ; metabolism ; Transfection

OBJECTIVE: To investigate the anti-leukemia effect of total saponins of Rubus parvifolius L. (TSRP) on K562 cell xenografts in nude mice and the mechanisms of action. METHODS: The K562 cell xenografts in nude mice were established, and then randomly divided into 5 groups, the control group, the cytosine arabinoside group(Ara-c) and 3 TSRP groups (20, 40 and 100 mg/kg). The tumor volume and mass of each group of nude mice were measured and the anti-tumor rates of TSRP were calculated subsequently. The apoptosis status of tumor cells was detected by hematoxylin-eosin (HE) and terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining analysis. Finally, the activities of apoptosis related signaling of signal transducer and activator of transcription 3 (STAT3), eukaryotic initiation factor 4E (eIF4E) and B-cell lymphoma-2 (bcl-2) were determined with immunohistochemistry tests. RESULTS: Subcutaneous injection of K562 cells induced tumor formation in nude mice, and the TSRP treated group showed a signifificant inhibitory effect on tumor formation. The nude mice treated with TSRP showed a signifificant decrease in tumor growth rate and tumor weight in comparison to the control group (all P<0.05). The HE staining and TUNEL assay showed that TSRP induced cell death by apoptosis. The immunohistochemical assay showed down-regulation of the bcl-2 gene in the TSRP treated cells. The phosphorylation levels of eIF4E and STAT3 were decreased obviously after the treatment of TSRP. CONCLUSION TSRP had an excellent tumor-suppressing effect on K562 cells in the nude mice xenograft model, suggesting that TSPR can be developed as a promising anti-chronic myeloide leukemia drug.
Animals ; Apoptosis ; drug effects ; Eukaryotic Initiation Factor-4E ; physiology ; Humans ; K562 Cells ; Leukemia ; drug therapy ; pathology ; Male ; Mice ; Rubus ; chemistry ; STAT3 Transcription Factor ; physiology ; Saponins ; pharmacology ; Signal Transduction ; drug effects ; Xenograft Model Antitumor Assays