Hinokitiol Inhibits the Viability of Oral Squamous Carcinoma Cells by Inducing Apoptosis and Autophagy.

BACKGROUND/AIM: Oral squamous cell carcinoma (OSCC) is one of the deadliest cancers, with approximately ~500,000 new diagnosed cases and 145,000 deaths worldwide, per year. The incidence of new cases continues to increase in developing countries. This study aimed to investigate the effect of hinokitiol on cell viability in OSCC cells. MATERIALS AND METHODS: The anticancer effect and mechanism of action of hinokitiol in OSCC cells were analyzed by cell viability assays and cell cycle analysis using flow cytometry, while apoptosis and autophagy-related protein expression was measured using western blot. RESULTS: The results showed that hinokitiol concentration-dependently reduced the viability of SCC4 and SCC25 cells by downregulating the levels of cell-cycle mediators, such as cyclin B1, cyclin D1 and cyclin-dependent kinase-1 (CDK1). Furthermore, hinokitiol promoted apoptosis in SCC25 cells based on the presence of active cleaved caspase-3. Hinokitiol also induced autophagy by promoting the accumulation of the microtubule-associated protein light chain 3B (LC3B) and the expression of the sequestosome-1 (p62/SQSTM). CONCLUSION: Hinokitiol exhibits anti-proliferation activity and has pro-apoptotic effects on OSCC cell lines.

Endoplasmic Reticulum Stress of Oral Squamous Cell Carcinoma Induces Immunosuppression of Neutrophils.

The endoplasmic reticulum (ER) stress of cancer cells not only determined cancer cell fate but also indirectly triggered proinflammatory or immunosuppressive responses of macrophages. In addition, ER stressed neutrophils were known to acquire immunosuppressive activity with surface expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). Since the importance of tumor ER stress and immunosuppressive neutrophils has been emphasized in head and neck cancers, we hypothesized that the ER stress of oral squamous cell carcinoma (OSCC) could transform neutrophils into LOX-1 expressing immunosuppressive phenotype. Two human OSCC cell lines, SCC25 and OML1, were treated with either vehicle or thapsigargin (THG), an ER stress inducer. These tumor conditioned media (TCM) were collected accordingly. Then human peripheral blood neutrophils from healthy donors were cultured in these TCM. The results showed that neutrophils cultured in THG-treated TCM had higher expression of LOX-1 compared with those cultured in vehicle-treated TCM. Moreover, by interleukin-2/anti-CD3/anti-CD28 activated autologous T cell proliferation assay, neutrophils conditioned by THG-treated TCM were shown to inhibit T cell proliferation more significantly than those conditioned by vehicle-treated TCM. These novel findings indicated that the ER stress of OSCC could be transmitted to neutrophils which in turn expressed LOX-1 and obtained immunosuppressive ability. Our findings further supported the existence of "transmissible" ER stress between tumor cells and neutrophils.

Alternative Complement Pathway Is Activated and Associated with Galactose-Deficient IgA1 Antibody in IgA Nephropathy Patients.

Background: Galactose-deficient IgA1 (Gd-IgA1) and alternative complement pathway activation are considered to be involved in the pathogenesis of IgA nephropathy (IgAN). Nevertheless, the relationships between alternative pathway activation and disease activity or Gd-IgA1 level remains unclear. Methods: Ninety-eight biopsy-diagnosed IgAN, twenty-five primary focal segmental sclerosis (FSGS) patients and forty-two healthy individuals were recruited in this study. Among them, fifty IgAN patients received immunosuppression. Follow-up blood samples at 1 and 3~6 months after immunosuppression were collected. Plasma levels of complement C5a, factor Ba and Gd-IgA1 were measured and analyzed. Immunostaining for complement was performed in twenty-five IgAN and FSGS patients. Results: At baseline, IgAN patients had higher levels of plasma C5a, factor Ba and Gd-IgA1 than control subjects. Gd-IgA1 levels positively correlated with plasma C5a and factor Ba. In addition, levels of factor Ba and Gd-IgA1 were positively associated with proteinuria and negatively associated with renal function. Immunostaining revealed positive staining for factor Bb and C3c in glomeruli in IgAN patients, but not in FSGS patients. At baseline, patients receiving immunosuppression had more severe proteinuria and higher factor Ba. After 6 months, eGFR declined and proteinuria persisted in patients without immunosuppression. In contrast, patients who received immunosuppression exhibited decreased plasma levels of C5a, factor Ba, and Gd-IgA1 as early as 1 month after treatment. Proteinuria decreased and renal function also remained stable 6 months after immunosuppression. Conclusions: Our results indicate a close relationship between alternative complement pathway activation, Gd-IgA1 concentration and clinical severity of IgAN. Level of complement factor B may be a potential marker for disease activity and therapeutic target in IgAN patients.

Developing a Decision-Aid Website for Breast Cancer Surgery: An Action Research Approach.

BACKGROUND: Patients with early-stage breast cancer have numerous options when choosing the type of breast surgery method to be applied. Each of these options lead to a similar long-term survival rate, but result in significant differences in appearance, function, cost, recurrence rate, and various other relevant considerations. However, the time available for detailed communication with each patient is often limited in clinics, which puts these women under great psychological stress and can hinder their surgery-related decision making. OBJECTIVE: The objective of this study was to develop a multipurpose surgery decision-making website providing medical information, psychological support, and decision-related simulation for women during breast cancer surgery-related decision making. METHODS: Using the 4 steps of action research, which involve multigroup teamwork via regular team meetings, the following were performed: (1) Planning: searching, analyzing, and evaluating health websites to consensually decide the major infrastructure; (2) Action: work was performed simultaneously in 4 groups, which consisted of medical information collection and editing, patient interviews and data extraction, webpage content design, and programming to create or host the website; (3) Evaluation: the website was tested by clinical experts and focus groups of former breast cancer patients to assess its effectiveness and pinpoint appropriate improvements; and (4) Reflection: constant dialogue was conducted between the various participants at each step, which was used as the foundation and motivation of next plan-action-evaluation-reflection circle. RESULTS: Using the action research approach, we completed the development of our website, which includes the following: (1) "Woman's Voice"-an animated comic depicting the story of a female breast cancer patient with interspersed questions for the users that will help them better empathize with the experience; (2) "Cancer Information Treasure House"-providing breast cancer surgery-related information through text, tables, pictures and a presentation video; (3) "Decision-making Simulator"-helping patients think through and check the pros and cons of the different surgical options via visual-based interactions including "Stairs Climbing" and "Fruit of Hope"; and (4) "Recommended Links"-providing reliable websites for further reference. Additionally, we have further improved the website based on the feedback received from postsurgery breast cancer patients and clinicians. We hope to continue improving to better meet both the patients' and health providers' needs and become a practical decision-making aid for patients undergoing breast cancer surgery. CONCLUSIONS: We have created the first breast cancer surgery decision-making assistance tool in Taiwan using a "Web-based" and multifunctional website design. This site aims to provide health care knowledge, psychological healing, and emotional support functions, as well as decision-making capability enhancement simulations. We look forward to assisting breast cancer patients in their decision-making process and expect our website to increase patient's autonomy and improve their communication with clinicians.

CDK4/6 Inhibitor LEE011 Is a Potential Radiation-sensitizer in Head and Neck Squamous Cell Carcinoma: An In Vitro Study.

BACKGROUND: Radiotherapy (RT) combined with a radiosensitizer represents an important treatment for head and neck squamous cell carcinoma (HNSCC). Only few chemotherapy agents are currently approved as radiosensitizers for targeted therapy. In this study, the potent cyclin-dependent kinase 4/6 (CDK4/6) inhibitor LEE011 was tested for potential to act as a radiosensitizer during RT. MATERIALS AND METHODS: RT enhancement by LEE011 was assessed by in vitro clonogenic assay, flow cytometry, and western blot in a variety of HNSCC cell lines. The HNSCC cell line OML1 and its radiation-resistant clone OML1-R were used. RESULTS: LEE011 induced cell-cycle arrest in SCC4/SCC25 cells during the G1/M phase through inhibition of retinoblastoma protein phosphorylation. LEE011 enhanced the effects of radiation in OML1 cells and overcame radiation resistance in OML1-R cells. CONCLUSION: LEE011 is a potential radiosensitizer that can enhance the cytotoxic effects of RT. Clinical trials including LEE011 during RT for HNSCC should be considered.

The relationship of anti-phospholipase A2 receptor antibody and C5a complement with disease activity and short-term outcome in idiopathic membranous nephropathy.

BACKGROUND: The binding of anti-phospholipase A2 receptor (anti-PLA2R) antibody to podocyte and complement activation is the mechanisms of idiopathic membranous nephropathy (IMN). C5a, a complement activation end product, is a strong inflammatory cell stimulator and can influence the behavior of T cells and dendritic cells. This study examined the etiology-disease relationship and significance of auto-antibody and C5a with short-term remission. METHOD: Plasma anti-PLA2R antibody and C5a were measured with the blood samples that were collected when patients were admitted for renal biopsy. The deposition of IgA, IgG, IgM, C1q and C3c in glomerulus was graded according to immunofluorescence staining. The relationship of anti-PLA2R antibody with C5a, glomerular immunoglobulin and complement deposition was examined. Antibody and C5a levels as predictors of short-term remission were also examined. RESULTS: In 72 IMN patients, 50 patients had positive plasma anti-PLA2R antibody. The antibody had positive correlation to proteinuria. Patients with high grade IgG or C3c, but not IgA/IgM/C1q, deposition had higher anti-PLA2R antibody titers. C5a was increased in IMN patients, but had no correlation with anti-PLA2R antibody or proteinuria. The analysis revealed that C5a, not initial anti-PLA2R antibody, was a predictor associated with 12-month remission in patients receiving immunosuppression with multivariate-adjusted OR 0.74 (95% CI, 0.58-0.94, P = 0.01). CONCLUSION: This study provides indirect evidences of etiology-disease relationship of anti-PLA2R antibody in IMN patients. The role of C5a, a predictor of remission, in the disease course of MN and the influences on inflammatory cells in MN patients is worth to be clarified.

High endothelin-converting enzyme-1 expression independently predicts poor survival of patients with esophageal squamous cell carcinoma.

Patients with esophageal squamous cell carcinoma have poor survival and high recurrence rate, thus an effective prognostic biomarker is needed. Endothelin-converting enzyme-1 is responsible for biosynthesis of endothelin-1, which promotes growth and invasion of human cancers. The role of endothelin-converting enzyme-1 in esophageal squamous cell carcinoma is still unknown. Therefore, this study investigated the significance of endothelin-converting enzyme-1 expression in esophageal squamous cell carcinoma clinically. We enrolled patients with esophageal squamous cell carcinoma who provided pretreated tumor tissues. Tumor endothelin-converting enzyme-1 expression was evaluated by immunohistochemistry and was defined as either low or high expression. Then we evaluated whether tumor endothelin-converting enzyme-1 expression had any association with clinicopathological findings or predicted survival of patients with esophageal squamous cell carcinoma. Overall, 54 of 99 patients with esophageal squamous cell carcinoma had high tumor endothelin-converting enzyme-1 expression, which was significantly associated with lymph node metastasis ( p = 0.04). In addition, tumor endothelin-converting enzyme-1 expression independently predicted survival of patients with esophageal squamous cell carcinoma, and the 5-year survival was poorer in patients with high tumor endothelin-converting enzyme-1 expression ( p = 0.016). Among patients with locally advanced and potentially resectable esophageal squamous cell carcinoma (stage II and III), 5-year survival was poorer with high tumor endothelin-converting enzyme-1 expression ( p = 0.003). High tumor endothelin-converting enzyme-1 expression also significantly predicted poorer survival of patients in this population. In patients with esophageal squamous cell carcinoma, high tumor endothelin-converting enzyme-1 expression might indicate high tumor invasive property. Therefore, tumor endothelin-converting enzyme-1 expression could be a good biomarker to identify patients with worse survival and higher risks of recurrence, who might benefit from the treatment by endothelin-converting enzyme-1 inhibitor.

Correction: IL-6 Expression Regulates Tumorigenicity and Correlates with Prognosis in Bladder Cancer.

[This corrects the article DOI: 10.1371/journal.pone.0061901.].

Type I IFNs induce anti-tumor polarization of tumor associated neutrophils in mice and human.

The importance of tumor associated neutrophils (TANs) in cancer development is in the meantime well established. Numerous of clinical data document the adverse prognostic effects of neutrophil infiltration in solid tumors. However, certain tumor therapies need functional neutrophils to be effective, suggesting altered neutrophil polarization associated with different outcomes for cancer patients. Therefore, modulation of neutrophilic phenotypes represents a potent therapeutic option, but factors mediating neutrophil polarization are still poorly defined. In this manuscript we provide evidence that type I IFNs alter neutrophilic phenotype into anti-tumor, both in mice and human. In the absence of IFN-ß, pro-tumor properties, such as reduced tumor cytotoxicity with low neutrophil extracellular traps (NETs) expression, low ICAM1 and TNF-α expression, dominated neutrophil phenotypes in primary lesion and premetastatic lung. Interestingly, such neutrophils have significantly prolonged life-span. Notably, interferon therapy in mice altered TAN polarization towards anti-tumor N1. Similar changes in neutrophil activation could be observed in melanoma patients undergoing type I IFN therapy. Altogether, these data highlight the therapeutic potential of interferons, suggesting optimization of its clinical use as potent anti-tumor agent.

The Efficacy of Postoperative Adjuvant Chemotherapy for Patients with pT3N0M0 Upper Tract Urothelial Carcinoma.

PURPOSE: Nephroureterectomy with bladder cuff excision may not be sufficient as monotherapy for patients with pT3N0M0 upper tract urothelial carcinoma. The efficacy of postoperative adjuvant chemotherapy in this setting remains controversial. We evaluated the efficacy of adjuvant chemotherapy for patients with pT3N0M0 upper tract urothelial carcinoma in overall, cancer specific and recurrence-free survival. MATERIALS AND METHODS: We retrospectively reviewed records on 171 consecutive patients with pT3N0M0 upper tract urothelial carcinoma treated with radical nephroureterectomy between 2004 and 2014 at 2 branches of the same institution. Postoperative adjuvant chemotherapy was gemcitabine/cisplatin or cisplatin/fluorouracil/leucovorin. Overall, cancer specific and recurrence-free survival rates were estimated using the Kaplan-Meier method. The values of prognostic factors were evaluated by Cox regression analysis. RESULTS: Postoperative adjuvant chemotherapy was administered in 60 patients vs nonadjuvant therapy in 111 patients. Median followup was 35.8 months. Between the adjuvant and nonadjuvant treatment groups there were statistically significant differences in 5-year cancer specific (80.5% vs 57.6%, p = 0.010) and recurrence-free (74.4% vs 52.9%, p = 0.026) survival rates. Although there was no statistically significant difference in overall survival (71.9% vs 49.0%, p = 0.072), there was a trend of better overall survival in the patients who received postoperative chemotherapy. On multivariable analysis age (p = 0.018), tumor location (p = 0.003) and adjuvant chemotherapy (p = 0.001) were predictors of cancer specific survival. CONCLUSIONS: Adjuvant chemotherapy improves cancer specific and recurrence-free survival in patients with pT3N0M0 upper tract urothelial carcinoma after radical nephroureterectomy.

The lack of type I interferon induces neutrophil-mediated pre-metastatic niche formation in the mouse lung.

Metastases are the major cause of death from cancer. Thus, understanding the regulation of metastatic processes is of utmost importance. Here we show that mice with impaired type I IFN signaling (Ifnar1(-/-)) develop more lung metastases in the 4T1 mammary and LLC lung carcinoma model, compared to control mice. In Ifnar1(-/-) mice, higher metastasis load is accompanied by massive neutrophil accumulation in lungs. Elevated G-CSF levels in serum and enhanced CXCR2 expression on neutrophils are most likely responsible for this phenomenon. Lung infiltrating neutrophils facilitate an improved pre-metastatic niche formation, supporting more efficient tumor cell extravasation and proliferation in this organ. This is due to the enhanced expression of pro-metastatic proteins, like Bv8, MMP9, S100A8 and S100A9. Development of pre-metastatic niche together with reduced neutrophil cytotoxicity against tumor cells results in enhanced metastatic processes in Ifnar1(-/-) mice. Overall, our findings describe a novel role for IFN during metastasis development and suggest that new treatment strategies should be considered for prevention of metastasis formation in patients.

Delayed apoptosis of tumor associated neutrophils in the absence of endogenous IFN-ß.

The importance of neutrophils in tumor immune surveillance, invasive growth and angiogenesis becomes increasingly clear. Many of neutrophil activities are controlled by endogenous IFN-ß. Here, we provide evidence that endogenous IFN-ß is regulating the apoptosis of pro-angiogenic tumor infiltrating neutrophils by influencing both, the extrinsic as well as the intrinsic apoptosis pathways. Accordingly, the life span of tumor associated neutrophils (TANs) is remarkably prolonged in tumor bearing Ifnb1(-/-) mice compared to wild type controls. Lower expression of Fas, reactive oxygen species, active Caspase 3 and 9, as well as a change in expression pattern of proapoptotic and antiapoptotic members of the Bcl-2 family and the major apoptosome constituent Apaf-1 is observed under such conditions. In line with inhibition of apoptosis and the prolonged neutrophil survival, in the absence of endogenous IFN-ß, a strong enhancement of G-CSF expression and PI3 Kinase phosphorylation is detected. These data explain the increased longevity of tumor infiltrating neutrophils and the accumulation of such cells in tumors. Taken together, our findings add to the important role of Type I IFN in immune surveillance against cancer.

Genome-wide mutational signatures of aristolochic acid and its application as a screening tool.

Aristolochic acid (AA), a natural product of Aristolochia plants found in herbal remedies and health supplements, is a group 1 carcinogen that can cause nephrotoxicity and upper urinary tract urothelial cell carcinoma (UTUC). Whole-genome and exome analysis of nine AA-associated UTUCs revealed a strikingly high somatic mutation rate (150 mutations/Mb), exceeding smoking-associated lung cancer (8 mutations/Mb) and ultraviolet radiation-associated melanoma (111 mutations/Mb). The AA-UTUC mutational signature was characterized by A:T to T:A transversions at the sequence motif A[C|T]AGG, located primarily on nontranscribed strands. AA-induced mutations were also significantly enriched at splice sites, suggesting a role for splice-site mutations in UTUC pathogenesis. RNA sequencing of AA-UTUC confirmed a general up-regulation of nonsense-mediated decay machinery components and aberrant splicing events associated with splice-site mutations. We observed a high frequency of somatic mutations in chromatin modifiers, particularly KDM6A, in AA-UTUC, demonstrated the sufficiency of AA to induce renal dysplasia in mice, and reproduced the AA mutational signature in experimentally treated human renal tubular cells. Finally, exploring other malignancies that were not known to be associated with AA, we screened 93 hepatocellular carcinoma genomes/exomes and identified AA-like mutational signatures in 11. Our study highlights an unusual genome-wide AA mutational signature and the potential use of mutation signatures as "molecular fingerprints" for interrogating high-throughput cancer genome data to infer previous carcinogen exposures.

IFN-γ production by CD27⁺ NK cells exacerbates Listeria monocytogenes infection in mice by inhibiting granulocyte mobilization.

Natural killer (NK) cells are key components of the immune system involved in several immune reactions, including the clearance of intracellular pathogens. When activated, NK cells rapidly secrete particular cytokines that activate innate immunity and facilitate development of adaptive responses. Conflicting reports on the role of NK cells during infection by Listeria monocytogenes can be found in the literature. Here, we demonstrate that during lethal infection by L. monocytogenes, activation of NK cells via the costimulatory molecule CD27 leads to excessive IFN-γ production. This impairs innate anti-bacterial host defenses by inducing downregulation of CXCR2 on granulocytes and consequently inhibiting their recruitment to the sites of infection. The use of antibodies to block CD27 signaling or to deplete IFN-γ was sufficient to rescue mice from lethal challenge by L. monocytogenes. Our findings contribute to a better understanding of the importance of CD27 signaling in activation of NK cells and should provide new ways of interfering with infections.

IL-6 expression regulates tumorigenicity and correlates with prognosis in bladder cancer.

Identification of potential tumor markers will help stratify and identify a tumor's malignant potential and its response to specific therapies. IL-6 has been reported to be a predictor in various cancers. Therefore, the present study was performed to highlight the role of IL-6 in improving treatment and determining prognosis of bladder cancer. The human bladder cancer cell lines HT1376 and HT1197 were selected for cell and animal experiments, in which biological changes after experimental manipulation of IL-6 were explored, including tumor behavior and related signaling in bladder cancer. In addition, clinical specimens from 85 patients with muscle-invasive, and 50 with non-muscle invasive bladder cancers were selected for immunohistochemical staining to evaluate the predictive capacity of IL-6 in relation to clinical outcome. The data revealed that IL-6 was overexpressed in the bladder cancer specimens compared with non-malignant tissues at both mRNA and protein levels. Positive staining of IL-6 was significantly correlated with higher clinical stage, higher recurrence rate after curative treatment, and reduced survival rate. Tumor growth and invasive capability were attenuated when IL-6 was blocked. The underlying changes included decreased cell proliferation, less epithelial-mesenchymal transition (EMT), decreased DNA methyltransferase 1 expression and attenuated angiogenesis. In conclusion, our findings showed that IL-6 could be a significant predictor for clinical stage and prognosis of bladder cancer. Moreover, targeting IL-6 may be a promising strategy for treating bladder cancer.

Transforming growth factor ß-1 stimulates profibrotic epithelial signaling to activate pericyte-myofibroblast transition in obstructive kidney fibrosis.

Pericytes have been identified as the major source of precursors of scar-producing myofibroblasts during kidney fibrosis. The underlying mechanisms triggering pericyte-myofibroblast transition are poorly understood. Transforming growth factor ß-1 (TGF-ß1) is well recognized as a pluripotent cytokine that drives organ fibrosis. We investigated the role of TGF-ß1 in inducing profibrotic signaling from epithelial cells to activate pericyte-myofibroblast transition. Increased expression of TGF-ß1 was detected predominantly in injured epithelium after unilateral ureteral obstruction, whereas downstream signaling from the TGF-ß1 receptor increased in both injured epithelium and pericytes. In mice with ureteral obstruction that were treated with the pan anti-TGF-ß antibody (1D11) or TGF-ß receptor type I inhibitor (SB431542), kidney pericyte-myofibroblast transition was blunted. The consequence was marked attenuation of fibrosis. In addition, epithelial cell cycle G2/M arrest and production of profibrotic cytokines were both attenuated. Although TGF-ß1 alone did not trigger pericyte proliferation in vitro, it robustly induced α smooth muscle actin (α-SMA). In cultured kidney epithelial cells, TGF-ß1 stimulated G2/M arrest and production of profibrotic cytokines that had the capacity to stimulate proliferation and transition of pericytes to myofibroblasts. In conclusion, this study identified a novel link between injured epithelium and pericyte-myofibroblast transition through TGF-ß1 during kidney fibrosis.

Expression and function role of DNA methyltransferase 1 in human bladder cancer.

BACKGROUND: The identification of potential tumor markers will help improve therapeutic planning and patient management. Therefore, the aim of this study was to highlight the role of DNA methyltransferase 1 (DNMT1) in bladder cancer. METHODS: A total of 50 samples of nonmalignant urothelium, 65 of muscle-invasive bladder cancers, 15 of distant metastasis, and 50 of nonmuscle-invasive bladder cancers were selected for immunohistochemical staining analysis. Furthermore, human bladder cancer cell lines HT1376 and HT1197 were selected for cell and animal experiments investigating changes in tumor behavior, treatment response, and related signaling in bladder cancer. RESULTS: The incidence of nuclear DNMT1 immunoreactivity in the bladder cancer specimens (45%) was significantly higher than in nonmalignant urothelium (15%, P = .0005), and the incidence in cancer was positively linked to clinical stage (24% in ≤T1 vs 55% in T2-T4, P = .0007). The staining of DNMT1 was also significantly linked to lower complete response rates (P = .0014) and reduced survival rates (P = .000). By in vitro and in vivo experiments, DNMT1 silencing vector reduced tumor growth and attenuated treatment resistance in bladder cancer cells. Less epithelial-mesenchymal transition, less invasion, and slower tumor growth were noted in cancer cells with inhibited DNMT1. Furthermore, the epidermal growth factor receptor-mediated phosphatidylinositol 3'-kinase-protein kinase B pathway might be the mechanism underlying the effects of DNMT1 on bladder cancer. CONCLUSIONS: DNMT1 could be a significant clinical predictor for stage and treatment response of bladder cancer. Moreover, targeting this enzyme could be a promising strategy for treating bladder cancer, as evidenced by inhibited tumor growth and enhanced radiosensitivity.

Targeting endothelium-pericyte cross talk by inhibiting VEGF receptor signaling attenuates kidney microvascular rarefaction and fibrosis.

Microvascular pericytes and perivascular fibroblasts have recently been identified as the source of scar-producing myofibroblasts that appear after injury of the kidney. We show that cross talk between pericytes and endothelial cells concomitantly dictates development of fibrosis and loss of microvasculature after injury. When either platelet-derived growth factor receptor (R)-ß signaling in pericytes or vascular endothelial growth factor (VEGF)R2 signaling in endothelial cells was blocked by circulating soluble receptor ectodomains, both fibrosis and capillary rarefaction were markedly attenuated during progressive kidney injury. Blockade of either receptor-mediated signaling pathway prevented pericyte differentiation and proliferation, but VEGFR2 blockade also attenuated recruitment of inflammatory macrophages throughout disease progression. Whereas injury down-regulated angiogenic VEGF164, the dys-angiogenic isomers VEGF120 and VEGF188 were up-regulated, suggesting that pericyte-myofibroblast differentiation triggers endothelial loss by a switch in secretion of VEGF isomers. These findings link fibrogenesis inextricably with microvascular rarefaction for the first time, add new significance to fibrogenesis, and identify novel therapeutic targets.