Interleukin-6 trans-signalling induces vascular endothelial growth factor synthesis partly via Janus kinases-STAT3 pathway in human mesothelial cells

Sterile inflammation of peritoneal membrane caused by peritoneal dialysis: focus on the communication between immune cells and peritoneal stroma

Peritoneal dialysis is a widely used method for treating kidney failure. However, over time, the peritoneal structure and function can deteriorate, leading to the failure of this therapy. This deterioration is primarily caused by infectious and sterile inflammation. Sterile inflammation, which is inflammation without infection, is particularly concerning as it can be subtle and often goes unnoticed. The onset of sterile inflammation involves various pathological processes. Peritoneal cells detect signals that promote inflammation and release substances that attract immune cells from the bloodstream. These immune cells contribute to the initiation and escalation of the inflammatory response. The existing literature extensively covers the involvement of different cell types in the sterile inflammation, including mesothelial cells, fibroblasts, endothelial cells, and adipocytes, as well as immune cells such as macrophages, lymphocytes, and mast cells. These cells work together to promote the occurrence and progression of sterile inflammation, although the exact mechanisms are not fully understood. This review aims to provide a comprehensive overview of the signals from both stromal cells and components of immune system, as well as the reciprocal interactions between cellular components, during the initiation of sterile inflammation. By understanding the cellular and molecular mechanisms underlying sterile inflammation, we may potentially develop therapeutic interventions to counteract peritoneal membrane damage and restore normal function.

STAT signaling as a target for intervention: from cancer inflammation and angiogenesis to non-coding RNAs modulation

As a landmark, scientific investigation in cytokine signaling and interferon-related anti-viral activity, signal transducer and activator of transcription (STAT) family of proteins was first discovered in the 1990s. Today, we know that the STAT family consists of several transcription factors which regulate various molecular and cellular processes, including proliferation, angiogenesis, and differentiation in human carcinoma. STAT family members play an active role in transducing signals from cell membrane to nucleus through intracellular signaling and thus activating gene transcription. Additionally, they are also associated with the development and progression of human cancer by facilitating inflammation, cell survival, and resistance to therapeutic responses. Accumulating evidence suggests that not all STAT proteins are associated with the progression of human malignancy; however, STAT3/5 are constitutively activated in various cancers, including multiple myeloma, lymphoma, breast cancer, prostate hepatocellular carcinoma, and non-small cell lung cancer. The present review highlights how STAT-associated events are implicated in cancer inflammation, angiogenesis and non-coding RNA (ncRNA) modulation to highlight potential intervention into carcinogenesis-related cellular processes.

High intraperitoneal interleukin-6 levels predict ultrafiltration (UF) insufficiency in peritoneal dialysis patients: A prospective cohort study

Introduction

UF insufficiency is a major limitation in PD efficiency and sustainability. Our study object to investigate the efficacy of intraperitoneal inflammation marker, IL-6 level as a predictor of UF insufficiency in continuous ambulatory peritoneal dialysis (CAPD) patients.

Methods

Stable prevalent CAPD patients were enrolled in this prospective study. IL-6 concentration in the overnight effluent was determined and expressed as the IL-6 appearance rate (IL-6 AR). Patients were divided into two groups according to the median of IL-6 AR and prospectively followed up until death, transfer to permanent HD, recovery of renal function, kidney transplantation, transfer to other centers, lost to follow-up or to the end of study (January 31, 2021). Factors associated with UF capacity as well as dialysate IL-6 AR were assessed by multivariable linear regression. Cox proportional hazards model was used to examine the association between dialysate IL-6 AR and UF insufficiency.

Results

A total of 291 PD patients were enrolled, including 148 males (51%) with a mean age of 56.6 ± 14.1 years and a median PD duration of 33.4 (12.7-57.5) months. No correlation was found between dialysate IL-6 AR and UF capacity at baseline. PD duration was found positively correlated with baseline dialysate IL-6 AR, while 24h urine volume was negatively correlated with baseline dialysate IL-6 AR (P < 0.05). By the end of study, UF insufficiency was observed in 56 (19.2%) patients. Patients in the high IL-6 AR group showed a significantly inferior UF insufficiency-free survival when compared with their counterparts in the low IL-6 AR group (P = 0.001). In the multivariate Cox regression analysis, after adjusting for DM, previous peritonitis episode and 24h urine volume, higher baseline dialysate IL-6 AR (HR 3.639, 95% CI 1.776-7.456, P = 0.002) were associated with an increased risk of UF insufficiency. The area under the ROC curve (AUC) for baseline IL-6 AR to predict UF insufficiency was 0.663 (95% CI, 0.580-0.746; P < 0.001).

Conclusion

Our study suggested that the dialysate IL-6 AR could be a potential predictor of UF insufficiency in patients undergoing PD.

Therapeutic Potential of Exosomal circRNA Derived from Synovial Mesenchymal Cells via Targeting circEDIL3/miR-485-3p/PIAS3/STAT3/VEGF Functional Module in Rheumatoid Arthritis

Background

Synovial inflammation and its associated activation of angiogenesis play critical roles in rheumatoid arthritis (RA). Exosomes, as carriers of genetic information including circular RNAs (circRNAs), have been explored as delivery vehicles for therapeutic molecules. However, the effects of synovial mesenchymal stem cells (SMSCs)-derived exosomal circRNAs and their mechanisms of action in RA progression remain unclear.

Methods

SMSCs-derived exosomes (SMSCs-Exos) were administered to a co-culture of RA fibroblast-like synoviocytes (RA-FLS) and human dermal microvascular endothelial cells (HDMECs) in vitro as well as to a collagen-induced arthritis (CIA) mouse model in vivo. Their effects on VEGF expression and angiogenic activity in vitro and the therapeutic efficacy in vivo were evaluated. Exosomes from circEDIL3-overexpressing SMSCs (Ad-circEDIL3-SMSCs-Exos) were used to further determine the role of circEDIL3 in SMSCs-Exo-based therapy.

Results

Both SMSCs-Exos and Ad-circEDIL3-SMSCs-Exos significantly downregulated the expression of VEGF induced by the IL-6/sIL-6R complex in the supernatants of RA-FLS and HDMECs co-culture as well as in the cell lysate of co-cultured RA-FLS, and the extent of reduction was more pronounced in the latter. Subsequent experiments showed that angiogenic activity was significantly downregulated by SMSCs-Exos and Ad-circEDIL3-SMSCs-Exos due to reduced VEGF expression. CircEDIL3 functioned as a sponge for miR-485-3p, which targeted PIAS3. PIAS3 is known to suppress STAT3 activity and reduce downstream VEGF. Injection of SMSCs-Exos or Ad-circEDIL3-SMSCs-Exos reduced synovial VEGF and consequently ameliorated arthritis severity in the CIA mouse model.

Conclusion

The intracellular transfer of circEDIL3 by SMSCs-Exos may be a potential novel therapeutic strategy for RA.

Trefoil Factor 3 Inhibits Thyroid Cancer Cell Progression Related to IL-6/JAK/STAT3 Signaling Pathway

Objectives

Abnormal expression of trefoil factor 3 (TFF3) in breast, stomach, and colon tumors may be related to the occurrence of tumors, suggesting its role in angiogenesis. In this study, the aim was to explore the role of TFF3 in thyroid cancer.

Methods

TFF3 expression analysis was performed via GEPIA and RT-PCR. To explore the effects of TFF3 on thyroid cancer cell motility, cell function assays were performed. Furthermore, GSEA pathway analysis and western blot were used to explore the mechanism by which TFF3 represses the progression of thyroid cancer cells.

Results

Here, we showed that low expression level of TFF3 in thyroid cancer is related to thyroid cancer nodal metastasis. The patients with low TFF3 expression showed worse disease-free survival than those with high level of TFF3. Underexpressed TFF3 increased cell motility and inhibited cell apoptosis. We found that the levels of IL-6, p-JAK2/JAK2, and pSTAT3/STAT3 were inhibited in the pcDNA-TFF3 group compared to the pcDNA-NC group and these factors were upregulated in the si-TFF3 group compared to the si-NC group in BCPAP and TPC-1 cells.

Conclusion

TFF3 inhibits thyroid cancer cell progression related to IL-6/JAK/STAT3 signaling pathway.

STAT3/HIF-1α signaling activation mediates peritoneal fibrosis induced by high glucose

BACKGROUND

Epithelial-mesenchymal transition (EMT) of mesothelial cells is a key step in the peritoneal fibrosis (PF). Recent evidence indicates that signal transducer and activator of transcription 3 (STAT3) might mediate the process of renal fibrosis, which could induce the expression of hypoxia-inducible factor-1α (HIF-1α). Here, we investigated the effect of STAT3 activation on HIF-1α expression and the EMT of mesothelial cells, furthermore the role of pharmacological blockade of STAT3 in the process of PF during peritoneal dialysis (PD) treatment.

METHODS

Firstly, we investigated the STAT3 signaling in human peritoneal mesothelial cells (HPMCs) from drained PD effluent. Secondly, we explored the effect of STAT3 signaling activation on the EMT and the expression of HIF-1α in human mesothelial cells (Met-5A) induced by high glucose. Finally, peritoneal fibrosis was induced by daily intraperitoneal injection with peritoneal dialysis fluid (PDF) so as to explore the role of pharmacological blockade of STAT3 in this process.

RESULTS

Compared with the new PD patient, the level of phosphorylated STAT3 was up-regulated in peritoneal mesothelial cells from long-term PD patients. High glucose (60 mmol/L) induced over-expression of Collagen I, Fibronectin, α-SMA and reduced the expression of E-cadherin in Met-5A cells, which could be abrogated by STAT3 inhibitor S3I-201 pretreatment as well as by siRNA for STAT3. Furthermore, high glucose-mediated STAT3 activation in mesothelial cells induced the expression of HIF-1α and the profibrotic effect of STAT3 signaling was alleviated by siRNA for HIF-1α. Daily intraperitoneal injection of high-glucose based dialysis fluid (HG-PDF) induced peritoneal fibrosis in the mice, accompanied by the phosphorylation of STAT3. Immunostaining showed that phosphorylated STAT3 was expressed mostly in α-SMA positive cells in the peritoneal membrane induced by HG-PDF. Administration of S3I-201 prevented the progression of peritoneal fibrosis, angiogenesis, macrophage infiltration as well as the expression of HIF-1α in the peritoneal membrane induced by high glucose.

CONCLUSIONS

Taken together, these findings identified a novel mechanism linking STAT3/HIF-1α signaling to peritoneal fibrosis during long-term PD treatment. It provided the first evidence that pharmacological inhibition of STAT3 signaling attenuated high glucose-mediated mesothelial cells EMT as well as peritoneal fibrosis.

Vascular endothelial growth factor-mediated peritoneal neoangiogenesis in peritoneal dialysis

Peritoneal dialysis (PD) is an important renal replacement therapy for patients with end-stage renal diseases, which is limited by peritoneal neoangiogenesis leading to ultrafiltration failure (UFF). Vascular endothelial growth factor (VEGF) and its receptors are key angiogenic factors involved in almost every step of peritoneal neoangiogenesis. Impaired mesothelial cells are the major sources of VEGF in the peritoneum. The expression of VEGF will be up-regulated in specific pathological conditions in PD patients, such as with non-biocompatible peritoneal dialysate, uremia and inflammation, and so on. Other working cells (i.e. vascular endothelial cells, macrophages and adipocytes) can also stimulate the secretion of VEGF. Meanwhile, hypoxia and activation of complement system further aggravate peritoneal injury and contribute to neoangiogenesis. There are several signalling pathways participating in VEGF-mediated peritoneal neoangiogenesis including tumour growth factor-β, Wnt/β-catenin, Notch and interleukin-6/signal transducer and activator of transcription 3. Moreover, VEGF is highly expressed in dialysate effluent of long-term PD patients and is associated with peritoneal transport function, which supports its role in the alteration of peritoneal structure and function. In this review, we systematically summarize the angiogenic effect of VEGF and evaluate it as a potential target for the prevention of peritoneal neoangiogenesis and UFF. Preservation of the peritoneal membrane using targeted therapy of VEGF-mediated peritoneal neoangiogenesis may increase the longevity of the PD modality for those who require life-long dialysis.

Targeting the JAK2/STAT3 Pathway-Can We Compare It to the Two Faces of the God Janus?

Muscle cachexia is one of the most critical unmet medical needs. Identifying the molecular background of cancer-induced muscle loss revealed a promising possibility of new therapeutic targets and new drug development. In this review, we will define the signal transducer and activator of transcription 3 (STAT3) protein's role in the tumor formation process and summarize the role of STAT3 in skeletal muscle cachexia. Finally, we will discuss a vast therapeutic potential for the STAT3-inhibiting single-agent treatment innovation that, as the desired outcome, could block tumor growth and generally prevent muscle cachexia.

Mesothelial Cells Participate in Endometriosis Fibrogenesis Through Platelet-Induced Mesothelial-Mesenchymal Transition

CONTEXT

While fibrosis in endometriosis has recently loomed prominently, the sources of myofibroblasts, the principal effector cell in fibrotic diseases, remain largely obscure. Mesothelial cells (MCs) can be converted into myofibroblasts through mesothelial-mesenchymal transition (MMT) in many fibrotic diseases and adhesion.

OBJECTIVE

To evaluate whether MCs contribute to the progression and fibrogenesis in endometriosis through MMT.

SETTING, DESIGN, PATIENTS, INTERVENTION, AND MAIN OUTCOME MEASURES

Dual immunofluorescence staining and immunohistochemistry using antibodies against calretinin, Wilms' tumor-1 (WT-1), and α-smooth muscle actin (α-SMA) were performed on lesion samples from 30 patients each with ovarian endometrioma (OE) and deep endometriosis (DE), and 30 normal endometrial (NE) tissue samples. Human pleural and peritoneal MCs were co-cultured with activated platelets or control medium with and without neutralization of transforming growth factor β1 (TGF-β1) and/or platelet-derived growth factor receptor (PDGFR) and their morphology, proliferation, and expression levels of genes and proteins known to be involved in MMT were evaluated, along with their migratory and invasive propensity, contractility, and collagen production.

RESULTS

The number of calretinin/WT-1 and α-SMA dual-positive fibroblasts in OE/DE lesions was significantly higher than NE samples. The extent of lesional fibrosis correlated positively with the lesional α-SMA staining levels. Human MCs co-cultured with activated platelets acquire a morphology suggestive of MMT, concomitant with increased proliferation, loss of calretinin expression, and marked increase in expression of mesenchymal markers. These changes coincided with functional differentiation as reflected by increased migratory and invasive capacity, contractility, and collagen production. Neutralization of TGF-β1 and PDGFR signaling abolished platelet-induced MMT in MCs.

CONCLUSIONS

MCs contribute to lesional progression and fibrosis through platelet-induced MMT.

IL-6 trans-signaling drives a STAT3-dependent pathway that leads to structural alterations of the peritoneal membrane

IL-6 is a vital inflammatory factor in the peritoneal cavity of patients undergoing peritoneal dialysis (PD). The present study examined the effect of IL-6 trans-signaling on structural alterations of the peritoneal membrane. We investigated whether the epithelial-to-mesenchymal transition (EMT) process of human peritoneal mesothelial cells (HPMCs) and the production of proangiogenic factors were controlled by IL-6 trans-signaling. Its role in the peritoneal alterations was detected in a mouse model. The morphology of HPMCs and levels of cytokines in PD effluent were also explored. Stimulation of HPMCs with the IL-6 and soluble IL-6 receptor complex (IL-6/S) promoted the EMT process of HPMCs depending on the STAT3 pathway. In a coculture system of HPMCs and human umbilical vein endothelial cells, IL-6/S mediated the production of VEGF and angiopoietins so as to downregulate the expression of endothelial junction molecules and finally affect vascular permeability. Daily intraperitoneal injection of high glucose-based dialysis fluid induced peritoneal fibrosis, angiogenesis, and macrophage infiltration in a mouse model, accompanied by phosphorylation of STAT3. Blockade of IL-6 trans-signaling prevented these peritoneum alterations. The fibroblast-like appearance of HPMCs ex vivo was upregulated in patients undergoing prevalent PD accompanied by increasing levels of IL-6, VEGF, and angiopoietin-2 in the PD effluent. Taken together, these findings identified a critical link between IL-6 trans-signaling and structural alterations of the peritoneal membrane, and it might be a potential target for the treatment of patients undergoing PD who have developed peritoneal alterations.

Low-Fiber Intake Is Associated With High Production of Intraperitoneal Inflammation Biomarkers

OBJECTIVE

Fiber intake influences disturbances in the gastrointestinal tract and is associated with systemic inflammation in the general population. Systemic and intraperitoneal inflammation play an important role in defining outcomes in peritoneal dialysis (PD), but the relationship between dietary fiber intake and inflammatory biomarkers has not yet been reported in the population on PD. The objective of the present study is to analyze whether or not fiber intake in patients on PD is associated with serum and intraperitoneal levels of inflammatory biomarkers.

DESIGN AND METHODS

Adult and clinically stable PD patients were included in this observational and cross-sectional study. Fiber intake was assessed by means of a dietary survey and calculated using the DietPro program 5.6i. The population was divided into two groups according to the median fiber intake. We investigated interleukin (IL)-1β, IL-6, tumor necrosis factor-α, monocyte chemoattractant protein-1 (MCP-1), B-cell-activating factor, and plasminogen-activator inhibitor-1 in both serum and peritoneal fluid. The latter was determined after a dwell time of 4 hours.

RESULTS

Fifty-two patients (42% men; aged 53 ± 14 years, 36% diabetics) were evaluated. Low intake of dietary fiber was found in 90% of patients, with a median of 12.2 g per day (3.4-33.3). The group with the highest fiber intake presented lower intraperitoneal levels of IL-6, IL-8, and MCP-1. In contrast, only MCP-1 was lower in the serum of those who consumed more fiber. All the associations remained significant after adjustment for confounders with plasminogen-activator inhibitor-1 included.

CONCLUSIONS

Patients on PD frequently present inadequate dietary fiber intake, which appears to have an association with the inflammatory response, particularly in the intraperitoneal component. Further prospective studies, evaluating whether or not a dietetic intervention with a focus on fiber intake affects these biomarkers and clinical outcomes, are essential to determine causality and clinical relevance.

Co-Expression of VEGF and IL-6 Family Cytokines is Associated with Decreased Survival in HER2 Negative Breast Cancer Patients: Subtype-Specific IL-6 Family Cytokine-Mediated VEGF Secretion

Breast cancer cell-response to inflammatory cytokines such as interleukin-6 (IL-6) and oncostatin M (OSM) may affect the course of clinical disease in a cancer subtype-dependent manner. Furthermore, vascular endothelial growth factor A (VEGF) secretion induced by IL-6 and OSM may also be subtype-dependent. Utilizing datasets from Oncomine, we show that poor survival of invasive ductal carcinoma (IDC) breast cancer patients is correlated with both high VEGF expression and high cytokine or cytokine receptor expression in tumors. Importantly, epidermal growth factor receptor-negative (HER2-), but not HER2-positive (HER2+), patient survival is significantly lower with high tumor co-expression of VEGF and OSM, OSMRβ, IL-6, or IL-6Rα compared to low co-expression. Furthermore, assessment of HER2- breast cancer cells in vitro identified unique signaling differences regulating cytokine-induced VEGF secretion. The levels of VEGF secretion were analyzed by ELISA with siRNAs for hypoxia inducible factor 1 α (HIF1α) and signal transducer and activator of transcription 3 (STAT3). Specifically, we found that estrogen receptor-negative (ER-) MDA-MB-231 cells respond only to OSM through STAT3 signaling, while ER+ T47D cells respond to both OSM and IL-6, though to IL-6 to a lesser extent. Additionally, in the ER+ T47D cells, OSM signals through both STAT3 and HIF1α. These results highlight that the survival of breast cancer patients with high co-expression of VEGF and IL-6 family cytokines is dependent on breast cancer subtype. Thus, the heterogeneity of human breast cancer in relation to IL-6 family cytokines and VEGF may have important implications in clinical treatment options, disease progression, and ultimately patient prognosis.

STAT3 in Skeletal Muscle Function and Disorders

Signal transducer and activator of transcription 3 (STAT3) signaling plays critical roles in regulating skeletal muscle mass, repair, and diseases. In this review, we discuss the upstream activators of STAT3 in skeletal muscles, with a focus on interleukin 6 (IL6) and transforming growth factor beta 1 (TGF-β1). We will also discuss the double-edged effect of STAT3 activation in the muscles, including the role of STAT3 signaling in muscle hypertrophy induced by exercise training or muscle wasting in cachectic diseases and muscular dystrophies. STAT3 is a critical regulator of satellite cell self-renewal after muscle injury. STAT3 knock out affects satellite cell myogenic progression by impairing proliferation and inducing premature differentiation. Recent studies in STAT3 signaling demonstrated its direct role in controlling myogenic capacity of myoblasts and satellite cells, as well as the potential benefit in using STAT3 inhibitors to treat muscle diseases. However, prolonged STAT3 activation in muscles has been shown to be responsible for muscle wasting by activating protein degradation pathways. It is important to balance the extent of STAT3 activation and the duration and location (cell types) of the STAT3 signaling when developing therapeutic interventions. STAT3 signaling in other tissues and organs that can directly or indirectly affects skeletal muscle health are also discussed.

Targeting STAT3 to Suppress Systemic Pro-Oncogenic Effects from Hepatic Radiofrequency Ablation

Purpose To (a) identify key expressed genes in the periablational rim after radiofrequency ablation (RFA) and their role in driving the stimulation of distant tumor growth and (b) use adjuvant drug therapies to block key identified mediator(s) to suppress off-target tumorigenic effects of hepatic RFA. Materials and Methods This institutional animal care and use committee-approved study was performed in C57BL6 mice (n = 20) and F344 rats (n = 124). First, gene expression analysis was performed in mice after hepatic RFA or sham procedure; mice were sacrificed 24 hours to 7 days after treatment. Data were analyzed for differentially expressed genes (greater than twofold change) and their functional annotations. Next, animals were allocated to hepatic RFA or sham treatment with or without STAT3 (signal transducer and activator of transcription 3) inhibitor S3I-201 for periablational phosphorylated STAT3 immunohistochemistry analysis at 24 hours. Finally, animals with subcutaneous R3230 adenocarcinoma tumors were allocated to RFA or sham treatment with or without a STAT3 inhibitor (S3I-201 or micellar curcumin, eight arms). Outcomes included distant tumor growth, proliferation (Ki-67 percentage), and microvascular density. Results At 24 hours, 217 genes had altered expression (107 upregulated and 110 downregulated), decreasing to 55 genes (27 upregulated and 28 downregulated) and 18 genes (four upregulated, 14 downregulated) at 72 hours and 7 days, respectively. At 24 hours, STAT3 occurred in four of seven activated pathways associated with pro-oncogenic genes at network analysis. Immunohistochemistry analysis confirmed elevated periablational phosphorylated STAT3 24 hours after RFA, which was suppressed with S3I-201 (percentage of positive cells per field: 31.7% ± 3.4 vs 3.8% ± 1.7; P < .001). Combined RFA plus S3I-201 reduced systemic distant tumor growth at 7 days (end diameter: 11.8 mm ± 0.5 with RFA plus S3I-201, 19.8 mm ± 0.7 with RFA alone, and 15 mm ± 0.7 with sham procedure; P < .001). STAT3 inhibition with micellar curcumin also suppressed postablation stimulation of distant tumor growth, proliferation, and microvascular density (P < .01). Conclusion Gene expression analysis identified multiple pathways upregulated in the periablational rim after hepatic RFA, of which STAT3 was active in four of seven. Postablation STAT3 activation is linked to increased distant tumor stimulation and can be suppressed with adjuvant STAT3 inhibitors. ^© RSNA, 2017.

Strategies for preventing peritoneal fibrosis in peritoneal dialysis patients: new insights based on peritoneal inflammation and angiogenesis

Peritoneal dialysis (PD) is an established form of renal replacement therapy. Long-term PD leads to morphologic and functional changes to the peritoneal membrane (PM), which is defined as peritoneal fibrosis, a known cause of loss of peritoneal ultrafiltration capacity. Inflammation and angiogenesis are key events during the pathogenesis of peritoneal fibrosis. This review discusses the pathophysiology of peritoneal fibrosis and recent research progress on key fibrogenic molecular mechanisms in peritoneal inflammation and angiogenesis, including Toll-like receptor ligand-mediated, NOD-like receptor protein 3/interleukin-1β, vascular endothelial growth factor, and angiopoietin-2/Tie2 signaling pathways. Furthermore, novel strategies targeting peritoneal inflammation and angiogenesis to preserve the PM are discussed in depth.

The roles of signal transducer and activator of transcription factor 3 in tumor angiogenesis

Angiogenesis is the development of new blood vessels, which is required for tumor growth and metastasis. Signal transducer and activator of transcription factor 3 (STAT3) is a transcription factor that regulates a variety of cellular events including proliferation, differentiation and apoptosis. Previous studies revealed that activation of STAT3 promotes tumor angiogenesis. In this review, we described the activities of STAT3 signaling in different cell types involved in angiogenesis. Particularly, we elucidated the molecular mechanisms of STAT3-mediated gene regulation in angiogenic endothelial cells in response to external stimulations such as hypoxia and inflammation. The potential for STAT3 as a therapeutic target was also discussed. Overall, this review provides mechanistic insights for the roles of STAT3 signaling in tumor angiogenesis.

Angiogenesis and Inflammation in Peritoneal Dialysis: The Role of Adipocytes

Chronic inflammation and angiogenesis are the most common complications in patients undergoing maintenance peritoneal dialysis (PD), resulting in progressive peritoneum remolding and, eventually, utrafiltration failure. Contributing to the deeper tissue under the peritoneal membrane, adipocytes play a neglected role in this process. Some adipokines act as inflammatory and angiogenic promoters, while others have the opposite effects. Adipokines, together with inflammatory factors and other cytokines, modulate inflammation and neovascularization in a coordinated fashion. This review will also emphasize cellular regulators and their crosstalk in long-term PD. Understanding the molecular mechanism, targeting changes in adipocytes and regulating adipokine secretion will help extend therapeutic methods for preventing inflammation and angiogenesis in PD.