Effect of platelet-rich and platelet-poor plasma on peri-implant innervation in dog mandibles.

BACKGROUND: Autologous plasma fractions, such as platelet-rich plasma (PRP) and platelet-poor plasma (PPP), contain growth factors that can enhance neural cell survival and are therefore likely to have the ability to promote nerve regeneration. The present study compared the effect of PRP and PPP application on myelinated nerve density and diameter in the peri-implant bone region. In addition, the effect of healing time on nerve regeneration was assessed. MATERIALS AND METHODS: Nine beagle dogs randomly received 54 dental implants in the bilateral mandible according to a split-mouth design. Each implant was randomly assigned to one of three implant protocols: delayed implant placement with delayed loading (DIP + DL) with local application of PRP, DIP + DL with local application of PPP and DIP + DL without any plasma additive. The animals were euthanized at 1, 3, and 6 months after loading (3 dogs per time point). Block biopsies were prepared for histomorphometry in the peri-implant bone within 500 µm around the implants. RESULTS: Myelinated nerve fibers were identified in the trabecular bone and in the osteons near the implants surface. The nerve fibers in the PRP group (median ± IQR; 2.88 ± 1.55 µm) had a significantly (p < 0.05) greater diameter compared to the PPP (2.40 ± 0.91 µm) and control (2.11 ± 1.16 µm) group. The nerve diameter after 6 months healing (3.18 ± 1.58 µm) was significantly (p < 0.05) greater compared to 1 (2.08 ± 0.89 µm) and 3 (2.49 ± 1.22 µm) months. No significant difference was found for myelinated nerve density between groups and healing time. CONCLUSIONS: The present study showed that the healing time significantly influenced the diameter of the myelinated nerve fibers in peri-implant bone. PRP exerted a significant effect on the diameter of the myelinated nerve fibers as compared to PPP. Large-scale animal studies and longer follow-up periods are needed to confirm these findings and to verify whether platelet plasma can facilitate nerve regeneration process.

High-throughput sequencing identifies aetiology-dependent differences in ductular reaction in human chronic liver disease.

Ductular reaction (DR) represents the activation of hepatic progenitor cells (HPCs) and has been associated with features of advanced chronic liver disease; yet it is not clear whether these cells contribute to disease progression and how the composition of their micro-environment differs depending on the aetiology. This study aimed to identify HPC-associated signalling pathways relevant in different chronic liver diseases using a high-throughput sequencing approach. DR/HPCs were isolated using laser microdissection from patient samples diagnosed with HCV or primary sclerosing cholangitis (PSC), as models for hepatocellular or biliary regeneration. Key signals were validated at the protein level for a cohort of 56 patients (20 early and 36 advanced stage). In total, 330 genes were significantly differentially expressed between the HPCs in HCV and PSC. Recruitment and homing of inflammatory cells were distinctly different depending on the aetiology. HPCs in PSC were characterised by a response to oxidative stress (e.g. JUN, VNN1) and neutrophil-attractant chemokines (CXCL5, CXCL6, IL-8), whereas HPCs in HCV were identified by T- and B-lymphocyte infiltration. Moreover, we found that communication between HPCs and macrophages was aetiology driven. In PSC, a high frequency of CCL28-positive macrophages was observed in the portal infiltrate, already in early disease in the absence of advanced fibrosis, while in HCV, HPCs showed a strong expression of the macrophage scavenger receptor MARCO. Interestingly, DR/HPCs in PSC showed more deposition of ECM (e.g. FN1, LAMC2, collagens) compared to HCV, where an increase of pro-invasive genes (e.g. PDGFRA, IGF2) was observed. Additionally, endothelial cells in the vicinity of DR/HPCs showed differential immunopositivity (e.g. IGF2 and INHBA expression). In conclusion, our data shine light on the role of DR/HPCs in immune signalling, fibrogenesis and angiogenesis in chronic liver disease. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Phenotype molding of stromal cells in the lung tumor microenvironment.

Cancer cells are embedded in the tumor microenvironment (TME), a complex ecosystem of stromal cells. Here, we present a 52,698-cell catalog of the TME transcriptome in human lung tumors at single-cell resolution, validated in independent samples where 40,250 additional cells were sequenced. By comparing with matching non-malignant lung samples, we reveal a highly complex TME that profoundly molds stromal cells. We identify 52 stromal cell subtypes, including novel subpopulations in cell types hitherto considered to be homogeneous, as well as transcription factors underlying their heterogeneity. For instance, we discover fibroblasts expressing different collagen sets, endothelial cells downregulating immune cell homing and genes coregulated with established immune checkpoint transcripts and correlating with T-cell activity. By assessing marker genes for these cell subtypes in bulk RNA-sequencing data from 1,572 patients, we illustrate how these correlate with survival, while immunohistochemistry for selected markers validates them as separate cellular entities in an independent series of lung tumors. Hence, in providing a comprehensive catalog of stromal cells types and by characterizing their phenotype and co-optive behavior, this resource provides deeper insights into lung cancer biology that will be helpful in advancing lung cancer diagnosis and therapy.

Sustained SREBP-1-dependent lipogenesis as a key mediator of resistance to BRAF-targeted therapy.

Whereas significant anti-tumor responses are observed in most BRAFV600E-mutant melanoma patients exposed to MAPK-targeting agents, resistance almost invariably develops. Here, we show that in therapy-responsive cells BRAF inhibition induces downregulation of the processing of Sterol Regulator Element Binding (SREBP-1) and thereby lipogenesis. Irrespective of the escape mechanism, therapy-resistant cells invariably restore this process to promote lipid saturation and protect melanoma from ROS-induced damage and lipid peroxidation. Importantly, pharmacological SREBP-1 inhibition sensitizes BRAFV600E-mutant therapy-resistant melanoma to BRAFV600E inhibitors both in vitro and in a pre-clinical PDX in vivo model. Together, these data indicate that targeting SREBP-1-induced lipogenesis may offer a new avenue to overcome acquisition of resistance to BRAF-targeted therapy. This work also provides evidence that targeting vulnerabilities downstream of oncogenic signaling offers new possibilities in overcoming resistance to targeted therapies.

Molecular Subtypes of Clear-cell Renal Cell Carcinoma are Prognostic for Outcome After Complete Metastasectomy.

BACKGROUND: Metastasectomy is routinely performed in selected patients with metastatic clear-cell renal cell carcinoma (ccRCC) as an alternative to systemic therapy. In the absence of randomized trials, the benefit and best way of patient selection remain unclear. Earlier, we described four molecular ccRCC-subtypes (ccrcc1-4) that have a prognostic and predictive value upon first-line sunitinib or pazopanib. OBJECTIVE: Assess the prognostic value of ccrcc1-4 subtypes after complete metastasectomy. (1) Compare outcomes of good-prognosis ccrccc2&3-tumors with intermediate/poor-prognosis ccrcc1&4-tumors. (2) Compare outcomes of the four subtypes separately. DESIGN, SETTING, AND PARTICIPANTS: Single-center retrospective study (1995-2017), assessing 43 ccRCC patients undergoing complete metastasectomy without systemic treatment. INTERVENTION: Molecular subtype determined with established 35-gene expression classifier. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Median disease-free survival (DFS), time to systemic therapy, cancer-specific (CSS) and overall survival (OS) from metastasectomy, estimated with Kaplan-Meier method and tested against other predictors with multivariable Cox regression. RESULTS AND LIMITATIONS: Median DFS was 23 mo for ccrcc2&3-tumors versus 9 mo for ccrcc1&4-tumors (p=0.011, hazard ratio [HR]=2.6). Median time to systemic therapy was 92 mo versus 28 mo (p=0.003, HR=3.3). Median CSS was 133 mo versus 50 mo (p<0.001, HR=2.7). Median OS was 127 mo versus 50 mo (p=0.011, HR=2.5). The classification remained independent upon multivariable analysis. Outcomes remained significantly different when comparing four subtypes separately. The intrinsic heterogeneity of expression profiles is a limitation of this approach. CONCLUSION: Even after clinical patient selection, patients with a ccrcc1- or ccrcc4-tumor are at a higher risk of relapse after complete metastasectomy. Patients with a ccrcc2- or ccrcc3-tumor usually experience a long DFS. These results need validation in a larger cohort to establish the subtypes as prognostic marker. PATIENT SUMMARY: Metastasectomy is recommended for some patients with metastatic clear-cell kidney cancer; however, we do not know who will benefit the most. We show that molecular subtypes increase the possibility to predict which patients are at risk for early relapse after metastasectomy and who may benefit more from other treatment options.

Myeloid-Related Protein-14/MRP-14/S100A9/Calgranulin B is Associated with Inflammation in Proliferative Diabetic Retinopathy.

PURPOSE: To investigate the expression of the leukocyte proteins myeloid-related protein (MRP)-8 and MRP-14 in proliferative diabetic retinopathy (PDR) and the effect of MRP-8/MRP-14 (calprotectin) heterodimer on induction of proinflammatory factors in human retinal microvascular endothelial cells (HRMEC). METHODS: Epiretinal membranes from 20 patients with PDR and 10 patients with proliferative vitreoretinopathy (PVR), vitreous fluid samples from PDR and non-diabetic subjects and HRMEC were studied by immunohistochemistry and Western blot analysis. RESULTS: MRP-14 expression was localized in endothelial cells, leukocytes and myofibroblasts in all PDR membranes. MRP-8 expression was limited to intravascular leukocytes in 42% of the studied membranes. In PVR membranes, MRP-14 was expressed in leukocytes and myofibroblasts, whereas MRP-8 immunoreactivity was limited to leukocytes. MRP-14 was significantly upregulated in vitreous from PDR patients. MRP-8/MRP-14 (calprotectin) increased expression of intercellular adhesion molecule-1, but attenuated vascular cell adhesion molecule-1 expression in HRMEC. CONCLUSIONS: Increased MRP-14 levels are associated with inflammation in PDR.

Molecular Subtypes of Clear Cell Renal Cell Carcinoma Are Associated With Outcome During Pazopanib Therapy in the Metastatic Setting.

BACKGROUND: We previously described 4 molecular subtypes of metastatic clear cell renal cell carcinoma (mccRCC), named ccrcc1-4 (Beuselinck et al, 2015). These have both prognostic and predictive value for patients treated with first-line sunitinib, with distinctive objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). The ccrcc2 and ccrcc3 tumors have the best outcomes, followed by ccrcc1 and then ccrcc4. We hypothesized that these molecular subtypes would show similar outcomes with first-line pazopanib treatment. PATIENTS AND METHODS: We classified 28 mccRCC tumors treated with pazopanib as first-line therapy, as described previously. The primary endpoints were PFS and OS from the start of pazopanib. A secondary endpoint was ORR. Because there were only 2 ccrcc3 tumors, they were pooled with the ccrcc2 tumors for outcome analysis. RESULTS: PFS was 9 months for the ccrcc2 and ccrcc3 tumors, 5 months for ccrcc1 tumors, and 3 months for the ccrcc4 tumors (P = .011). The corresponding OS duration was 69, 19, and 5 months (P = .003). The corresponding ORR was 50%, 33%, and 0%. The corresponding mean tumor size decreased by 34%, 6%, and 2% (P = .032). The ccrcc1-4 classification was a stronger predictor of outcome than the International Metastatic Renal Cell Carcinoma Database Consortium score on univariate analysis (P = .011 vs. P = .094 for PFS and P = .003 vs. .013 for OS). Both remained independent on bivariate analysis. CONCLUSION: The molecular subtypes of mccRCC are associated with outcome on pazopanib as first-line therapy. The prognostic and predictive value of the ccrcc1-4 molecular classification requires validation in prospective trials.

Pathogenic CD8+ T Cells Cause Increased Levels of VEGF-A in Experimental Malaria-Associated Acute Respiratory Distress Syndrome, but Therapeutic VEGFR Inhibition Is Not Effective.

Malaria is a severe disease and kills over 400,000 people each year. Malarial complications are the main cause of death and include cerebral malaria and malaria-associated acute respiratory distress syndrome (MA-ARDS). Despite antimalarial treatment, lethality rates of MA-ARDS are still between 20 and 80%. Patients develop pulmonary edema with hemorrhages and leukocyte extravasation in the lungs. The vascular endothelial growth factor-A (VEGF-A) and the placental growth factor (PlGF) are vascular permeability factors and may be involved in the disruption of the alveolar-capillary membrane, leading to alveolar edema. We demonstrated increased pulmonary VEGF-A and PlGF levels in lungs of mice with experimental MA-ARDS. Depletion of pathogenic CD8+ T cells blocked pulmonary edema and abolished the increase of VEGF-A and PlGF. However, neutralization of VEGF receptor-2 (VEGFR-2) with the monoclonal antibody clone DC101 did not decrease pulmonary pathology. The broader spectrum receptor tyrosine kinase inhibitor sunitinib even increased lung pathology. These data suggest that the increase in alveolar VEGF-A and PlGF is not a cause but rather a consequence of the pulmonary pathology in experimental MA-ARDS and that therapeutic inhibition of VEGF receptors is not effective and even contra-indicated.

The footprint of the ageing stroma in older patients with breast cancer.

BACKGROUND: Tumours are not only composed of malignant cells but also consist of a stromal micro-environment, which has been shown to influence cancer cell behaviour. Because the ageing process induces accumulation of senescent cells in the body, this micro-environment is thought to be different in cancers occurring in old patients compared with younger patients. More specifically, senescence-related fibroblastic features, such as the senescence-associated secretory profile (SASP) and the induction of autophagy, are suspected to stimulate tumour growth and progression. METHODS: We compared gene expression profiles in stromal fields of breast carcinomas by performing laser capture microdissection of the cancer-associated stroma from eight old (aged ≥80 years at diagnosis) and nine young (aged <45 years at diagnosis) patients with triple-negative breast cancer. Gene expression data were obtained by microarray analysis (Affymetrix). Differential gene expression and gene set enrichment analysis (GSEA) were performed. RESULTS: Differential gene expression analysis showed changes reminiscent of increased growth, de-differentiation and migration in stromal samples of older versus younger patients. GSEA confirmed the presence of a SASP, as well as the presence of autophagy in the stroma of older patients. CONCLUSIONS: We provide the first evidence in humans that older age at diagnosis is associated with a different stromal micro-environment in breast cancers. The SASP and the presence of autophagy appear to be important age-induced stromal features.

End-stage cystic fibrosis lung disease is characterised by a diverse inflammatory pattern: an immunohistochemical analysis.

BACKGROUND: Cystic fibrosis (CF) lung disease is characterised by vigorous airway inflammation eventually resulting in severe lung damage. This study aimed to describe the diversity of the inflammatory pattern in end-stage CF lungs by evaluating and quantifying which components of the innate and adaptive immunity are involved, and by assessing whether this is gender-specific. METHODS: CF explant lung tissue (n = 20) collected at time of transplantation and control tissue (n = 22) was sectioned (9 µm) and stained for neutrophils, eosinophils, mast cells, dendritic cells, macrophages, CD4 T cells, cytotoxic T cells and B cells. Quantification with special attention for immune cell location was performed. RESULTS: Neutrophils, mast cells, dendritic cells, macrophages, CD4 T and cytotoxic T cells were significantly increased in CF compared to controls and there was a disproportionate increase of neutrophils around the airways in CF. Large amounts of lymphoid follicles were found in the CF lung and they had a skewed B cell/T cell composition. Upon subdividing the CF patients into a male and female population, eosinophils, mast cells and CD4 T cells were increased specifically in CF females. In this subpopulation, lymphoid follicles had less B cells and more CD8 T cells. CONCLUSION: These data demonstrate a diverse inflammatory response in the CF lung, reflected by an increase of both myeloid and lymphoid immune cells. Inflammation in the CF lung appeared to be gender-specific in our population, as the significant increase of eosinophils, mast cells and CD4 T cells was especially notable in the female subpopulation.

Immunological diversity in phenotypes of chronic lung allograft dysfunction: a comprehensive immunohistochemical analysis.

Chronic rejection after organ transplantation is defined as a humoral- and cell-mediated immune response directed against the allograft. In lung transplantation, chronic rejection is nowadays clinically defined as a cause of chronic lung allograft dysfunction (CLAD), consisting of different clinical phenotypes including restrictive allograft syndrome (RAS) and bronchiolitis obliterans syndrome (BOS). However, the differential role of humoral and cellular immunity is not investigated up to now. Explant lungs of patients with end-stage BOS (n = 19) and RAS (n = 18) were assessed for the presence of lymphoid (B and T cells) and myeloid cells (dendritic cells, eosinophils, mast cells, neutrophils, and macrophages) and compared to nontransplant control lung biopsies (n = 21). All myeloid cells, with exception of dendritic cells, were increased in RAS versus control (neutrophils, eosinophils, and mast cells: all P < 0.05, macrophages: P < 0.001). Regarding lymphoid cells, B cells and cytotoxic T cells were increased remarkably in RAS versus control (P < 0.001) and in BOS versus control (P < 0.01). Interestingly, lymphoid follicles were restricted to RAS (P < 0.001 versus control and P < 0.05 versus BOS). Our data suggest an immunological diversity between BOS and RAS, with a more pronounced involvement of the B-cell response in RAS characterized by a structural organization of lymphoid follicles. This may impact future therapeutic approaches.

The Presence of Endometrial Cells in Peritoneal Fluid of Women With and Without Endometriosis.

To reinforce Sampson's theory of retrograde menstruation in the pathogenesis of endometriosis, proof should be provided that during menstruation endometrial cells are present in peritoneal fluid (PF). We hypothesize that the prevalence of PF samples containing endometrial cells is higher in patients with endometriosis than in controls without endometriosis during menstruation. We selected from our biobank PF samples of 17 reproductive-age women with (n = 9) or without (n = 8) endometriosis who had received a diagnostic laparoscopy for investigation of pain/infertility. Peritoneal fluid had been collected during laparoscopy in the menstrual phase of the cycle, centrifuged, and the resulting pellet was stored at -80°C. About 5-µm sections of frozen PF pellets were stained using the Dako Envision Flex system with primary antibodies against epithelial cell adhesion molecule (Ep-CAM; endometrial epithelial cells), CD10 (endometrial stromal cells), prekeratin (epithelial/mesothelial cells), vimentin (endometrial/mesothelial/immune cells), calretinin (mesothelial cells), and CD68 (macrophages). The PF cells positive for Ep-CAM were detected in 5 of 9 patients with endometriosis and 6 of 8 controls ( P = .62). CD10 stained positively in 6 of the 9 patients with endometriosis and 3 of the 8 controls ( P = .35). Calretinin and prekeratin staining showed the presence of mesothelial cells in all pellets. Vimentin stained approximately 100% of the PF cells. CD68+ macrophages represented >50% of cells in all pellets. The prevalence of PF samples containing endometrial epithelial and stromal cells was not higher in patients with endometriosis than in controls without endometriosis during menstruation. Our findings question the relevance of endometrial cells in PF for the pathogenesis of endometriosis and support the importance of other mechanisms such as immune dysfunction and/or endometrial stem cells.

Upregulation of Thrombin/Matrix Metalloproteinase-1/Protease-Activated Receptor-1 Chain in Proliferative Diabetic Retinopathy.

PURPOSE: Selective proteolytic activation of protease-activated receptor-1 (PAR1) by thrombin and matrix metalloproteinase-1 (MMP-1) plays a central role in enhancing angiogenesis. We investigated the expression levels of thrombin, MMP-1, and PAR1 and correlated these levels with vascular endothelial growth factor (VEGF) in proliferative diabetic retinopathy (PDR). In addition, we examined the expression of PAR1 and thrombin in the retinas of diabetic rats and PAR1 in human retinal microvascular endothelial cells (HRMEC) following exposure to high-glucose, the proinflammatory cytokines interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and the hypoxia mimetic agent cobalt chloride (CoCl2). METHODS: Vitreous samples from 32 PDR and 23 nondiabetic patients, epiretinal membranes from 10 patients with PDR, retinas of rats, and HRMEC were studied by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and Western blot analysis. An assay for in vitro cell migration angiogenesis was performed in HRMEC. RESULTS: In epiretinal membranes, PAR1 was expressed in vascular endothelial cells, CD45-expressing leukocytes, and myofibroblasts. ELISA and Western blot assays revealed significant increases in the expression levels of thrombin, MMP-1, and VEGF in vitreous samples from PDR patients compared to nondiabetic controls. Significant positive correlations were found between the levels of VEGF and the levels of thrombin (r = 0.41; p = 0.006) and MMP-1 (r = 0.66; p < 0.0001). Significant increases of cleaved PAR1 (approximately 50 kDa) and the proteolytically active thrombin (approximately 50 kDa) were detected in rat retinas after induction of diabetes. The proinflammatory cytokines IL-1ß and TNF-α, but not high-glucose and CoCl2, induced upregulation of cleaved PAR1 (approximately 30 kDa) in HRMEC. In addition, thrombin and MMP-1 induced VEGF in HRMEC and vorapaxar, a PAR1 inhibitor, inhibited thrombin-induced migration in HRMEC. CONCLUSIONS: Interactions among thrombin, MMP-1, PAR1, and VEGF might facilitate angiogenesis in PDR.

Regenerative endodontic procedure of an infected immature permanent human tooth: an immunohistological study.

OBJECTIVES: An immunohistological study of an infected immature permanent human tooth after a regenerative endodontic procedure (REP) was conducted in order to determine the histologic outcome of this procedure. Besides observed signs of angiogenesis and neurogenesis, repair and/or regeneration of the pulp-dentin complex was also investigated. MATERIALS AND METHODS: A REP was performed on tooth 45 of a 10-year-old girl. Eleven months post-treatment, the tooth had to be removed for orthodontic reasons. The following investigations were performed: immunohistology and radiographic quantification of root development. After hematoxylin-eosin (HE) staining, the following immunomarkers were selected: neurofilament (NF), pan cytokeratin (PK), osteocalcin (OC), and CD34. RESULTS: The REP resulted in clinical and radiographic healing of the periradicular lesion and quantifiable root development. The HE staining matches with the medical imaging post-REP: underneath the mineral trioxide aggregate a calcified bridge with cell inclusions, connective pulp-like tissue (PLT) with blood vessels, osteodentin against the root canal walls, on the root surface cementum (Ce), and periodontal ligament (PDL). The PDL was PK(+). The blood vessels in the PLT and PDL were CD34(+). The Ce, osteodentin, and stromal cells in the PLT were OC(+). The neurovascular bundles in the PLT were NF(+). CONCLUSIONS: Immunohistologically, REP of this infected immature permanent tooth resulted in an intracanalar connective tissue with a regulated physiology, but not pulp tissue. CLINICAL RELEVANCE: REP of an immature permanent infected tooth may heal the periapical infection and may result in a combination of regeneration and repair of the pulp-dentin complex.

Laminin-332 sustains chemoresistance and quiescence as part of the human hepatic cancer stem cell niche.

BACKGROUND & AIMS: Cancer stem cells (CSCs) are thought to be persistent in tumours due to their chemoresistance and to cause relapse and metastasis. Hepatic carcinomas displaying hepatic progenitor cell (HPC) features have been associated with a poor prognosis, though it remains unclear how CSCs relate to these different histological subtypes. METHODS: Candidate CSCs were isolated using the side population (SP) technique from primary tissue samples diagnosed as keratin(K)19-negative or -positive hepatocellular carcinoma (HCC) or as combined hepatocellular/cholangiocarcinoma and analysed for gene and protein expression. The effect of laminin-332 was analysed in vitro by using HCC cell lines and in vivo using a xenograft mouse model. RESULTS: The size of the SP correlated with the degree of HPC features found in human hepatic cancer, and also showed an elevated mRNA expression of biliary/HPC markers and the extracellular matrix marker LAMC2, the gene encoding the laminin γ2-chain. Immunopositivity for the γ2-chain of laminin-332 was seen in the extracellular matrix surrounding small HPC-like tumour cells with a low proliferation rate. In vitro, laminin-332 increased K19 expression, phosphorylated mTOR and decreased phospho-histone H3 expression, indicating reduced cell mitosis. The effect of laminin-332 was enhanced upon mTORC1 inhibition and diminished when inhibiting mTORC1+C2. Resistance to doxorubicin and sorafenib treatment, and the SP fraction increased in the coated condition. In vivo, laminin-332 reduced tumour growth and sustained K19 expression. CONCLUSIONS: In this study we identified a prominent role for laminin-332 as part of the specialised CSC niche in maintaining and supporting cell 'stemness', which leads to chemoresistance and quiescence.

Myofibroblasts in proliferative diabetic retinopathy can originate from infiltrating fibrocytes and through endothelial-to-mesenchymal transition (EndoMT).

Myofibroblasts expressing α-smooth muscle actin (α-SMA) are the key cellular mediator of fibrosis. Fibrovascular epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) are characterized by the accumulation of a large number of myofibroblasts. We explored the hypothesis that proliferating endothelial cells via endothelial-to-mesenchymal transition (EndoMT) and/or bone marrow-derived circulating fibrocytes contribute to the myofibroblast population present in PDR epiretinal membranes. Epiretinal membranes from 14 patients with PDR were studied by immunohistochemistry. All membranes contained neovessels expressing the endothelial cell marker CD31. CD31(+) endothelial cells co-expressed the fibroblast/myofibroblast markers fibroblast-specific protein-1 (FSP-1) and α-SMA, indicative for the occurrence of endoMT. In the stroma, cells expressing FSP-1, α-SMA, the leukocyte common antigen CD45, and the myelomonocytic marker CD11b were detected. Double labeling showed co-localization of CD45 with FSP-1 and α-SMA and co-localization of CD11b with α-SMA and matrix metalloproteinase-9, demonstrating the presence of infiltrating fibrocytes. In addition, we investigated the phenotypic changes that take place in human retinal microvascular endothelial cells following exposure to transforming growth factor-ß1 (TGF-ß1), connective tissue growth factor (CTGF) and the proinflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α). Retinal microvascular endothelial cells changed morphology upon cytokine exposure, lost the expression of endothelial cell markers (endothelial nitric oxide synthase and vascular endothelial-cadherin) and started to express mesenchymal markers (calponin, snail, transgelin and FSP-1). These results suggest that endothelial cells as well as circulating fibrocytes may differentiate into myofibroblasts in the diabetic eye and contribute to pathologic fibrosis in PDR.

The Chemokine Platelet Factor-4 Variant (PF-4var)/CXCL4L1 Inhibits Diabetes-Induced Blood-Retinal Barrier Breakdown.

PURPOSE: To investigate the expression of platelet factor-4 variant (PF-4var/CXCL4L1) in epiretinal membranes from patients with proliferative diabetic retinopathy (PDR) and the role of PF-4var/CXCL4L1 in the regulation of blood-retinal barrier (BRB) breakdown in diabetic rat retinas and human retinal microvascular endothelial cells (HRMEC). METHODS: Rats were treated intravitreally with PF-4var/CXCL4L1 or the anti-vascular endothelial growth factor (VEGF) agent bevacizumab on the first day after diabetes induction. Blood-retinal barrier breakdown was assessed in vivo with fluorescein isothiocyanate (FITC)-conjugated dextran and in vitro in HRMEC by transendothelial electrical resistance and FITC-conjugated dextran cell permeability assay. Occludin, vascular endothelial (VE)-cadherin, hypoxia-inducible factor (HIF)-1α, VEGF, tumor necrosis factor (TNF)-α, receptor for advanced glycation end products (RAGE), caspase-3 levels, and generation of reactive oxygen species (ROS) were assessed by Western blot, enzyme-linked immunosorbent assays, or spectrophotometry. RESULTS: In epiretinal membranes, vascular endothelial cells and stromal cells expressed PF-4var/CXCL4L1. In vitro, HRMEC produced PF-4var/CXCL4L1 after stimulation with a combination of interleukin (IL)-1ß and TNF-α, and PF-4var/CXCL4L1 inhibited VEGF-mediated hyperpermeability in HRMEC. In rats, PF-4var/CXCL4L1 was as potent as bevacizumab in attenuating diabetes-induced BRB breakdown. This effect was associated with upregulation of occludin and VE-cadherin and downregulation of HIF-1α, VEGF, TNF-α, RAGE, and caspase-3, whereas ROS generation was not altered. CONCLUSIONS: Our findings suggest that increasing the intraocular PF-4var/CXCL4L1 levels early after the onset of diabetes protects against diabetes-induced BRB breakdown.

The tumor necrosis factor superfamily members TWEAK, TNFSF15 and fibroblast growth factor-inducible protein 14 are upregulated in proliferative diabetic retinopathy.

PURPOSE: Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and tumor necrosis factor superfamily member 15 (TNFSF15), members of the TNF superfamily, play important roles in the modulation of inflammation and neovascularization. TWEAK activity is mediated via binding to fibroblast growth factor-inducible molecule 14 (Fn14). We investigated the expression of TWEAK, Fn14 and TNFSF15 and the correlation between TWEAK levels and the levels of the inflammatory biomarker soluble intercellular adhesion molecule-1 (sICAM-1) in proliferative diabetic retinopathy (PDR). In addition, we examined the expression of FN14 and TNFSF15 in retinas of diabetic rats. METHODS: Vitreous samples from 34 PDR and 23 nondiabetic patients were studied by enzyme-linked immunosorbent assay and Western blot analysis. Epiretinal membranes from 14 patients with PDR were studied by immunohistochemistry. The retinas of rats were examined by Western blot analysis. RESULTS: We identified a significant increase in the expression of TWEAK, Fn14, TNFSF15 and sICAM-1 in vitreous samples from PDR patients compared to controls. A significant positive correlation was found between levels of TWEAK and levels of sICAM-1 (r = 0.3, p = 0.02). In epiretinal membranes, TWEAK and TNFSF15 protein expression was confined to vascular endothelial cells, monocytes/macrophages and myofibroblasts. Significant positive correlations were observed between the number of blood vessels expressing CD34 and the number of blood vessels expressing TWEAK (r = 0.670; p = 0.017) and TNFSF15 (r = 0.784; p = 0.001). The expression level of TNFSF15 was upregulated in the retinas of diabetic rats, whereas Fn14 was not upregulated. CONCLUSIONS: Our findings suggest that TNFSF15 and the TWEAK/Fn14 pathway are novel mediators involved in persistent inflammation and modulation of pathological neovascularization associated with PDR.

Upregulated Expression of Heparanase in the Vitreous of Patients With Proliferative Diabetic Retinopathy Originates From Activated Endothelial Cells and Leukocytes.

PURPOSE: To determine and interrelate the levels of heparanase, syndecan-1, and VEGF in proliferative diabetic retinopathy (PDR), and to study the production of heparanase by human retinal microvascular endothelial cells (HRMEC) and its effect on HRMEC barrier function. METHODS: Vitreous samples from 33 PDR and 27 nondiabetic patients, epiretinal membranes from 16 patients with PDR and HRMEC were studied by enzyme-linked immunosorbent assay, immunohistochemistry, and Western blot analysis. The effect of heparanase on HRMEC barrier function was evaluated by transendothelial electrical resistance. RESULTS: We showed a significant increase in the expression of heparanase, syndecan-1, and VEGF in vitreous samples from PDR patients compared with nondiabetic controls (P < 0.0001 for all comparisons). Significant positive correlations were found between the levels of heparanase and the levels of syndecan-1 (r = 0.75, P < 0.0001) and VEGF (r = 0.91, P < 0.0001) and between the levels of syndecan-1 and the levels of VEGF (r = 0.78, P < 0.0001). In epiretinal membranes, heparanase was expressed in vascular endothelial cells and CD45-expressing leukocytes. High-glucose, tumor necrosis factor alpha (TNF-α), and the combination of TNF-α and interleukin (IL)-1ß, but not cobalt chloride induced upregulation of heparanase in HRMEC. Heparanase-reduced transendothelial electrical resistance of HRMEC. CONCLUSIONS: Our findings suggest a link between heparanase, syndecan-1, and VEGF in the progression of PDR and that heparanase is a potential target for therapy of diabetic retinopathy.

The angiogenic biomarker endocan is upregulated in proliferative diabetic retinopathy and correlates with vascular endothelial growth factor.

PURPOSE/AIM: Endocan is a proteoglycan specifically secreted by endothelial cells, is a marker of angiogenesis and endothelial cell activation in response to proangiogenic signals. The aim of this study was to measure the levels of endocan in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate its levels with clinical disease activity and the levels of the angiogenic biomarkers vascular endothelial growth factor (VEGF), soluble vascular endothelial-cadherin (sVE-cadherin) and soluble endoglin (sEng). In addition, we investigated the expression of endocan and correlated it with the level of vascularization in PDR epiretinal membranes. MATERIALS AND METHODS: Vitreous samples from 44 PDR and 29 non-diabetic patients were studied by enzyme-linked immunosorbent assay. Epiretinal membranes from 14 patients with PDR were studied by immunohistochemistry. RESULTS: Endocan, VEGF, sVE-cadherin and sEng levels were significantly higher in PDR patients than in non-diabetic patients (p < 0.001; p = 0.002; p < 0.001; p = 0.001, respectively). Endocan levels were significantly higher in patients with active PDR than in patients with inactive PDR and non-diabetic patients (p < 0.001). There were significant positive correlations between endocan levels and the levels of VEGF (r = 0.574, p < 0.001) and sVE-cadherin (r = 0.498, p < 0.001). In epiretinal membranes, vascular endothelial cells and myofibroblasts expressed endocan. There was a significant positive correlation between the number of blood vessels expressing CD34 and the number of blood vessels expressing endocan (r = 0.933, p < 0.001). CONCLUSIONS: Our findings suggest that upregulation of endocan expression in PDR could be a reflection of endothelial cell activation associated with angiogenesis.