Active and acid-activatable TGF-beta in human sera, platelets and plasma

Coronary artery bypass grafting (CABG) induces pro-inflammatory and immunomodulatory phenotype of platelets in the absence of a pro-aggregatory state

BACKGROUND

Coronary artery bypass grafting (CABG) is considered the choice treatment for patients suffering from coronary artery disease (CAD). In the inflammatory milieu of cardiopulmonary bypass (CPB), systemic inflammatory response syndrome (SIRS) can induce a platelet pro-inflammatory state which could exacerbate post-CABG inflammatory status while affecting hemostatic function in patients. Therefore, focusing on platelets, the study presented here attempted to evaluate the pro-inflammatory and immunomodulatory profile of platelets as well as pro-aggregatory status during CABG.

METHODS

Platelets from patients undergoing CABG were subjected to flowcytometry analysis to evaluate P-selectin and CD40L expressions and PAC-1 binding in five intervals of 24 h before surgery, immediately, 2 h, 24 h, and one week after surgery. Moreover, intra-platelet TGF-β1 was also examined with western blotting.

RESULTS

Data showed increases of P-selectin and CD40L expressions in patients, with the meaningful loss of platelet contents of TGF-β1 after CABG (p < 0.001), where the changes tended to recover by day 7 of surgery while remaining above baseline (p < 0.001). Meanwhile, no significant change in PAC-1 binding capacity was shown.

CONCLUSION

The study presented here suggests that although the release of pro-inflammatory substances from platelets during CABG supports the post-operative inflammatory state, platelets are not pro-aggregatory enough to enhance thrombotic events after surgery. Whilst these observations could be due to successful medical interventions to optimize hemostasis during and after surgery, post-CABG reversal of anticoagulant by protamine is considered as another factor that may also have contributed to preventing pro-aggregatory but not pro-inflammatory and immunomodulatory functions of platelets.

Serum-Induced Proliferation of Human Cardiac Stem Cells Is Modulated via TGFβRI/II and SMAD2/3

The ageing phenotype is strongly driven by the exhaustion of adult stem cells (ASCs) and the accumulation of senescent cells. Cardiovascular diseases (CVDs) and heart failure (HF) are strongly linked to the ageing phenotype and are the leading cause of death. As the human heart is considered as an organ with low regenerative capacity, treatments targeting the rejuvenation of human cardiac stem cells (hCSCs) are of great interest. In this study, the beneficial effects of human blood serum on proliferation and senescence of hCSCs have been investigated at the molecular level. We show the induction of a proliferation-related gene expression response by human blood serum at the mRNA level. The concurrent differential expression of the TGFβ target and inhibitor genes indicates the participation of TGFβ signalling in this context. Surprisingly, the application of TGFβ1 as well as the inhibition of TGFβ type I and type II receptor (TGFβRI/II) signalling strongly increased the proliferation of hCSCs. Likewise, both human blood serum and TGFβ1 reduced the senescence in hCSCs. The protective effect of serum on senescence in hCSCs was enhanced by simultaneous TGFβRI/II inhibition. These results strongly indicate a dual role of TGFβ signalling in terms of the serum-mediated effects on hCSCs. Further analysis via RNA sequencing (RNA-Seq) revealed the participation of Ras-inactivating genes wherefore a prevention of hyperproliferation upon serum-treatment in hCSCs via TGFβ signalling and Ras-induced senescence is suggested. These insights may improve treatments of heart failure in the future.

TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor β (TGF-β) directly acts on naive, effector, and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer; however, the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or proinflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β before or after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

Transforming growth factor beta 1 (TGF-β1) in COVID-19 patients: relation to platelets and association with the disease outcome

Transforming growth factor beta (TGF-β) is a ubiquitously distributed cytokine known to contribute to the pathogenesis of numerous pathological processes. The aim of this study was to measure serum concentrations of TGF-β1 in severely ill COVID-19 patients and to analyze its relationship with selected hematological and biochemical parameters and with the disease outcome. The study population included 53 COVID-19 patients with severe clinical expression of the disease and 15 control subjects. TGF-β1 was determined in serum samples and supernatants from PHA-stimulated whole blood cultures using ELISA assay. Biochemical and hematological parameters were analyzed using standard accepted methods. Our results showed that serum levels of TGF-β1 in COVID-19 patients and controls correlate with the platelet counts. Also, positive correlations of TGF-β1 with white blood cell and lymphocyte counts, platelet-to-lymphocyte (PLR) ratio, and fibrinogen level were shown, while negative correlations of this cytokine with platelet distribution width (PDW), D-dimer and activated partial thromboplastin time (a-PTT) values in COVID-19 patients were observed. The lower serum values of TGF-β1 were associated with the unfavorable outcome of COVID-19. In conclusion, TGF-β1 levels were strongly associated with platelet counts and unfavorable disease outcome of severely ill COVID-19 patients.

TGF-β broadly modifies rather than specifically suppresses reactivated memory CD8 T cells in a dose-dependent manner

Transforming growth factor β (TGF-β) directly acts on naïve, effector and memory T cells to control cell fate decisions, which was shown using genetic abrogation of TGF-β signaling. TGF-β availability is altered by infections and cancer, however the dose-dependent effects of TGF-β on memory CD8 T cell (Tmem) reactivation are still poorly defined. We examined how activation and TGF-β signals interact to shape the functional outcome of Tmem reactivation. We found that TGF-β could suppress cytotoxicity in a manner that was inversely proportional to the strength of the activating TCR or pro-inflammatory signals. In contrast, even high doses of TGF-β had a comparatively modest effect on IFN-γ expression in the context of weak and strong reactivation signals. Since CD8 Tmem may not always receive TGF-β signals concurrently with reactivation, we also explored whether the temporal order of reactivation versus TGF-β signals is of importance. We found that exposure to TGF-β prior to as well as after an activation event were both sufficient to reduce cytotoxic effector function. Concurrent ATAC-seq and RNA-seq analysis revealed that TGF-β altered ~10% of the regulatory elements induced by reactivation and also elicited transcriptional changes indicative of broadly modulated functional properties. We confirmed some changes on the protein level and found that TGF-β-induced expression of CCR8 was inversely proportional to the strength of the reactivating TCR signal. Together, our data suggest that TGF-β is not simply suppressing CD8 Tmem, but modifies functional and chemotactic properties in context of their reactivation signals and in a dose-dependent manner.

TGF-β at the crossroads of multiple prognosis in breast cancer, and beyond

Transforming growth factor β (TGF-β), a pluripotent cytokine and a multifunctional growth factor has a crucial role in varied biological mechanisms like invasion, migration, epithelial-mesenchymal transition, apoptosis, wound healing, and immunosuppression. Moreover, it also has an imperative role both in normal mammary gland development as well as breast carcinogenesis. TGF-β has shown to have a paradoxical role in breast carcinogenesis, by transitioning from a growth inhibitor to a growth promoter with the disease advancement. The inter-communication and crosstalk of TGF-β with different signaling pathways has strengthened the likelihood to explore it as a comprehensive biomarker. In the last two decades, TGF-β has been studied extensively and has been found to be a promising biomarker for early detection, disease monitoring, treatment selection, and tumor progression making it beneficial for disease management. In this review, we focus on the signaling pathways and biological activities of the TGF-β family in breast cancer pathogenesis and its role as a circulatory and independent biomarker for breast cancer progression and metastasis. Moreover, this review highlights TGF-β as a drug target, and the underlying mechanisms through which it is involved in tumorigenesis that will aid in the development of varied therapies targeting the different stages of breast cancer.

Plasma Kallikrein-Activated TGF-β Is Prognostic for Poor Overall Survival in Patients with Pancreatic Ductal Adenocarcinoma and Associates with Increased Fibrogenesis

Pancreatic ductal adenocarcinoma (PDAC) is a hard-to-treat cancer due to the collagen-rich (fibrotic) and immune-suppressed microenvironment. A major driver of this phenomenon is transforming growth factor beta (TGF-β). TGF-β is produced in an inactive complex with a latency-associated protein (LAP) that can be cleaved by plasma kallikrein (PLK), hereby releasing active TGF-β. The aim of this study was to evaluate LAP cleaved by PLK as a non-invasive biomarker for PDAC and tumor fibrosis. An ELISA was developed for the quantification of PLK-cleaved LAP-TGF-β in the serum of 34 patients with PDAC (stage 1−4) and 20 healthy individuals. Biomarker levels were correlated with overall survival (OS) and compared to serum type III collagen (PRO-C3) and type VI collagen (PRO-C6) pro-peptides. PLK-cleaved LAP-TGF-β was higher in patients with PDAC compared to healthy individuals (p < 0.0001). High levels (>median) of PLK-cleaved LAP-TGF-β were associated with poor OS in patients with PDAC independent of age and stage (HR 2.57, 95% CI: 1.22−5.44, p = 0.0135). High levels of PLK-cleaved LAP-TGF-β were associated with high PRO-C3 and PRO-C6, indicating a relationship between the PLK-cleaved LAP-TGF-β fragment, TGF-β activity, and tumor fibrosis. If these preliminary results are validated, circulating PLK-cleaved LAP-TGF-β may be a biomarker for future clinical trials.

Alignment of practices for data harmonization across multi-center cell therapy trials: a report from the Consortium for Pediatric Cellular Immunotherapy

Immune effector cell (IEC) therapies have revolutionized our approach to relapsed B-cell malignancies, and interest in the investigational use of IECs is rapidly expanding into other diseases. Current challenges in the analysis of IEC therapies include small sample sizes, limited access to clinical trials and a paucity of predictive biomarkers of efficacy and toxicity associated with IEC therapies. Retrospective and prospective multi-center cell therapy trials can assist in overcoming these barriers through harmonization of clinical endpoints and correlative assays for immune monitoring, allowing additional cross-trial analysis to identify biomarkers of failure and success. The Consortium for Pediatric Cellular Immunotherapy (CPCI) offers a unique platform to address the aforementioned challenges by delivering cutting-edge cell and gene therapies for children through multi-center clinical trials. Here the authors discuss some of the important pre-analytic variables, such as biospecimen collection and initial processing procedures, that affect biomarker assays commonly used in IEC trials across participating CPCI sites. The authors review the recent literature and provide data to support recommendations for alignment and standardization of practices that can affect flow cytometry assays measuring immune effector function as well as interpretation of cytokine/chemokine data. The authors also identify critical gaps that often make parallel comparisons between trials difficult or impossible.

Total Versus Free Placental Growth Factor Levels in the Pathogenesis of Preeclampsia

Elevated circulating sFLT-1 (soluble fms-like tyrosine kinase) and low levels of its ligand, PlGF (placental growth factor), are key characteristics of preeclampsia. However, it is unclear if the low levels of plasma PlGF noted during preeclampsia are due to decreased placental production of PlGF or due to binding of PlGF by increased circulating sFLT-1. Here, we describe a biochemical procedure to dissociate PlGF-sFLT-1 complex ex vivo and when used in conjunction with an immunoassay platform, demonstrate a method to measure total and free PlGF in human blood samples. Using this method, we noted that plasma free PlGF levels were significantly lower in preeclampsia (N=22) than in nonhypertensive controls (N=24; mean, 314 versus 686 pg/mL, P<0.05), but total PlGF levels were not different (mean, 822 versus 800 pg/mL, P=0.49). In contrast, total sFLT-1 levels were significantly higher in preeclampsia than in nonhypertensive controls (mean, 16 957 versus 3029 pg/mL, P<0.01) and sFLT-1 levels correlated with bound PlGF levels (bound PlGF=total PlGF-free PlGF) in these samples (r²=0.68). We confirmed these findings in an independent cohort of subjects (N=49). Furthermore, we did not detect any difference in PlGF mRNA by quantitative polymerase chain reaction or in PlGF protein expression by immunohistochemistry in preeclamptic placentas when compared with nonhypertensive controls. In contrast, sFLT-1 mRNA and protein levels were upregulated in placentas from women with preeclampsia. Taken together with prior studies, our results provide evidence that decrease in circulating PlGF noted during preeclampsia is largely mediated by excess circulating sFLT-1.

New methodologies to accurately assess circulating active transforming growth factor-β1 levels: implications for evaluating heart failure and the impact of left ventricular assist devices

Transforming growth factor-β1 (TGF-β1) has been used as a biomarker in disorders associated with pathologic fibrosis. However, plasma TGF-β1 assessment is confounded by the significant variation in reported normal values, likely reflecting variable release of the large pool of platelet TGF-β1 after blood drawing. Moreover, current assays measure only total TGF-β1, which is dominated by the latent form of TGF-β1 rather than the biologically active form. To address these challenges, we developed methodologies to prevent ex vivo release of TGF-β1 and to quantify active TGF-β1. We then used these techniques to measure TGF-β1 in healthy controls and patients with heart failure (HF) before and after insertion of left ventricular assist devices (LVAD). Total plasma TGF-β1 was 1.0 ± 0.60 ng/mL in controls and 3.76 ± 1.55 ng/mL in subjects with HF (P < 0.001), rising to 5.2 ± 2.3 ng/mL following LVAD placement (P = 0.006). These results were paralleled by the active TGF-β1 values; controls had 3-16 pg/mL active TGF-β1, whereas levels were 2.7-fold higher in patients with HF before, and 4.2-fold higher after, LVAD implantation. Total TGF-β1 correlated with levels of the platelet-derived protein thrombospondin-1 (r = 0.87; P < 0.001), suggesting that plasma TGF-β1 may serve as a surrogate indicator of in vivo platelet activation. von Willebrand factor high molecular weight multimers correlated inversely with TGF-β1 levels (r = -0.63; P = 0.023), suggesting a role for shear forces in loss of these multimers and platelet activation. In conclusion, accurate assessment of circulating TGF-β1 may provide a valuable biomarker for in vivo platelet activation and thrombotic disorders.

Cytokine responses to exercise and activity in patients with chronic fatigue syndrome: case-control study

Chronic fatigue syndrome (CFS) is characterized by fatigue after exertion. A systematic review suggested that transforming growth factor (TGF)-β concentrations are often elevated in cases of CFS when compared to healthy controls. This study attempted to replicate this finding and investigate whether post-exertional symptoms were associated with altered cytokine protein concentrations and their RNA in CFS patients. Twenty-four patients fulfilling Centers for Disease Control criteria for CFS, but with no comorbid psychiatric disorders, were recruited from two CFS clinics in London, UK. Twenty-one healthy, sedentary controls were matched by gender, age and other variables. Circulating proteins and RNA were measured for TGF-β, tumour necrosis factor (TNF), interleukin (IL)-8, IL-6 and IL-1β. We measured six further cytokine protein concentrations (IL-2, IL-4, IL-5, IL-10, IL-12p70, and interferon (IFN)-γ). Measures were taken at rest, and before and after both commuting and aerobic exercise. CFS cases had higher TGF-β protein levels compared to controls at rest (median (quartiles) = 43·9 (19·2, 61·8) versus 18·9 (16·1, 30·0) ng/ml) (P = 0·003), and consistently so over a 9-day period. However, this was a spurious finding due to variation between different assay batches. There were no differences between groups in changes to TGF-β protein concentrations after either commuting or exercise. All other cytokine protein and RNA levels were similar between cases and controls. Post-exertional symptoms and perceived effort were not associated with any increased cytokines. We were unable to replicate previously found elevations in circulating cytokine concentrations, suggesting that elevated circulating cytokines are not important in the pathophysiology of CFS.

Elevated Bioactivity of the Tolerogenic Cytokines, Interleukin-10 and Transforming Growth Factor-β, in the Blood of Acutely Malnourished Weanling Mice

The main objective of this investigation was to determine the influence of acute deficits of protein and energy on the blood levels of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), physiologically the main anti-inflammatory and tolerogenic cytokines. In four 14-day experiments, male and female C57BL/6J mice, initially 19 days old, consumed a complete purified diet either ad libitum or in restricted daily quantities, or had free access to an isocaloric purified low-protein diet. A zero-time control group (19 days old) was included. In the first two experiments, serum IL-10 levels were assessed by sandwich enzyme-linked immunosorbent assay (ELISA) and bioassay. The mean serum IL-10 bioactivities were higher (P ≤ 0.05) in both malnourished groups (low-protein and restricted intake: 15.8 and 12.2 ng/ml, respectively) than in the zero-time and age-matched control groups (6.3 and 7.3 ng/ml, respectively), whereas serum IL-10 immunoactivity was high only in the restricted intake group (e.g., second experiment: 17.0 pg/ml vs. 5.4, 3.7, and 3.1 pg/ml in the zero-time control, age-matched control and low-protein group, respectively). The third and fourth experiments centered on plasma TGF-β immunoactivity (sandwich ELISA) and bioactivity, respectively. The ELISA revealed a high mean plasma TGF-β1 level (P < 0.05) in the low-protein group only, but TGF-β bioactivity (β1 isoform, although 15% β2 in the restricted intake group) was high in both malnourished groups (8.7 and 9.3 ng/ml in the low-protein and restricted groups, respectively) relative to the age-matched control group (0.5 ng/ml). Thus, metabolically distinct weanling systems mimicking marasmus and incipient kwashiorkor both exhibit a blood cytokine profile that points to a tolerogenic microenvironment within immune response compartments. A model emerges in which malnutrition-associated immune competence, at least in advanced weight loss, centers on cytokine-mediated peripheral tolerance that reduces the risk of catabolically induced autoimmune disease, but this is at the cost of attenuated responsiveness to infectious agents.

Inhibition of TGFβ cell signaling for limbal explant culture in serumless, defined xeno-free conditions

Outgrowths of limbal epithelium by explant culture are used to treat limbal stem cell deficiency (LSCD). The explant culture medium is always complemented with serum, a complex solution which includes TGFβ. Since TGFβ is a cytostatic effector for epithelial proliferation we examined its effect on these cultures. Limbal biopsies were set on explant culture in DMEM/F12 with 5 ng/ml EGF and cholera toxin (ChT), ITS, and 5% FBS, henceforth SHEM or a) SHEMSB=SHEM plus SB431542 an inhibitor of TGFβ signaling; b) sfSHEM = SHEM with FBS replaced by 0.05% Albumax II; and c) sfSHEMSB and sfSHEMA83 = sfSHEM plus, respectively, SB431542 or A-83-01, another TGFβ inhibitor. After the initial outgrowths reached 3 cm in diameter, the limbal biopsies were serially transferred up to six times onto new inserts. Biopsy explant outgrowths were trypsinized and cell yield, morphology and stem-cell related JC-1 exclusion (IOVS, 52:4330) were determined by flow cytometry. Cells we plated at low density seeding to compare relative clonal proliferative activity. The expression of three proteins whose levels are associated with growth and differentiation states, Krt3, connexin 43 and p63 were determined by immunohistology and/or Western blot. Cell yield in rabbit, relative to SHEM (in %) were, SHEMSB, 104 ± 13 (p > 0.95); sfSHEM: 5 ± 3; and sfSHEMSB, 94 ± 18 (p > 0.95). Cell size and morphology, JC1 dye exclusion, Krt3, p63 and connexin 43 content, proliferation efficiency and the preservation of extended proliferative potential of the serially cultured biopsies were similar for SHEM, SHEMSB and sfSHEMSB. The only differences observed where reduced expression of Krt3 and increased preservation of p63 in the FBS-free medium. Removal of EGF from sfSHEMSB reduced yield by 92 ± 6% (p < 0.05). Removal of Albumax and ChT to establish a xeno-free medium caused a small, non-statistical decrease in growth rates. Equivalent results were observed in a preliminary experiment in human. These results suggest that in the absence serum endogenously generated TGFβ act as an autocrine cytostatic agent and that TGFβ inhibitors allow explant culture in xeno-free, chemically defined medium. Furthermore, the pro-growth effect of serum in limbal explant cultures may result exclusively from neutralization of the TGFβ cytostatic effect.

Immunoglobulin A in serum: an old acquaintance as a new prognostic biomarker in idiopathic pulmonary fibrosis

Immunoglobulin (Ig)A is an important immunoglobulin in mucosal immunity and protects the lungs against invading pathogens. The production of IgA is regulated by transforming growth factor (TGF)-β, a versatile cytokine and key player in the pathogenesis of pulmonary fibrosis. TGF-β is up-regulated in patients with idiopathic pulmonary fibrosis (IPF), but difficult to use as a biomarker. The aim of this study was to evaluate the prognostic value of IgA in serum in patients with IPF. We examined IgA levels at time of diagnosis in 86 patients diagnosed with IPF. Mean serum IgA level in IPF is 3·22 g/l and regression analyses showed a significant association with mortality (hazard ratio = 1·445, P = 0·002). A significantly worse survival was found in patients with IgA serum levels > 2·85 g/l compared to patients with lower IgA serum levels (P = 0·003). These findings were confirmed in a duplication cohort. In conclusion, the level of IgA in blood is a promising prognostic marker in IPF and can be implemented easily in the hospital setting. Future studies are warranted to investigate if repeated measurements of serum IgA can further improve the performance of serum IgA as a prognostic marker.

Development of a novel multiplexed assay for quantification of transforming growth factor-β (TGF-β)

Changes in activity or levels of transforming growth factor-β (TGF-β) are associated with a variety of diseases; however, measurement of TGF-β in biological fluids is highly variable. TGF-β is biologically inert when associated with its latency-associated peptide (LAP). Most available immunoassays require exogenous activation by acid/heat to release TGF-β from the latent complex. We developed a novel electrochemiluminescence-based multiplexed assay on the MesoScale Discovery® platform that eliminates artificial activation, simultaneously measures both active TGF-β1 and LAP1 and includes an internal control for platelet-derived TGF-β contamination in blood specimens. We optimized this assay to evaluate plasma levels as a function of activation type and clinical specimen preparation. We determined that breast cancer patients' plasma have higher levels of circulating latent TGF-β (LTGF-β) as measured by LAP1 than healthy volunteers (p < 0.0001). This assay provides a robust tool for correlative studies of LTGF-β levels with disease, treatment outcomes and toxicity with a broad clinical applicability.

Expression of angiogenesis regulatory proteins and epithelial-mesenchymal transition factors in platelets of the breast cancer patients

Platelets play a role in tumor angiogenesis and growth and are the main transporters of several angiogenesis regulators. Here, we aimed to determine the levels of angiogenesis regulators and epithelial-mesenchymal transition factors sequestered by circulating platelets in breast cancer patients and age-matched healthy controls. Platelet pellets (PP) and platelet-poor plasma (PPP) were collected by routine protocols. Vascular endothelial growth factor (VEGF), platelet-derived growth factor BB (PDGF-BB), thrombospondin-1 (TSP-1), platelet factor 4 (PF4), and transforming growth factor-β1 (TGF-β1) were measured by enzyme-linked immunosorbent assay. Angiogenesis-associated expression of VEGF (2.1 pg/10⁶ platelets versus 0.9 pg/10⁶ platelets, P < 0.001), PF4 (21.2 ng/10⁶ platelets versus 10.2 ng/10⁶ platelets, P < 0.001), PDGF-BB (42.9 pg/10⁶ platelets versus 19.1 pg/10⁶ platelets, P < 0.001), and TGF-β1 (15.3 ng/10⁶ platelets versus 4.3 ng/10⁶ platelets, P < 0.001) differed in the PP samples of cancer and control subjects. In addition, protein concentrations were associated with clinical characteristics (P < 0.05). Circulating platelets in breast cancer sequester higher levels of PF4, VEGF, PDGF-BB, and TGF-β1, suggesting a possible target for early diagnosis. VEGF, PDGF, and TGF-β1 concentrations in platelets may be associated with prognosis.

Age-dependent defective TGF-beta1 signaling in patients undergoing coronary artery bypass grafting

Background

Transforming growth factor beta (TGF-β1) is a pleiotropic cytokine, which is deregulated in atherosclerosis; however the role of age in this process is unknown. We aimed to assess whether TGF-β1 signaling is affected by age.

Methods

Vascular smooth muscle cells (VSMC) were obtained from patients undergoing abdominal surgery. Levels of TGF-β1 were measured by ELISA in sera from 169 patients undergoing coronary artery bypass grafting (CABG). The p27 expression was determined by Western blot from internal mammary arteries (IMA) obtained from CABG patients (n = 13). In VSMC from these patients undergoing abdominal surgery, secretion of TGF-β1 was determined by ELISA of cell-conditioned media.

Results

In VSMC from aged patients we observed a lower TGF-β1 secretion, measured as TGF-β1 concentration in cell conditioned medium (p < 0.001). This effect was correlated to an age-dependent decrease of p27 expression in IMA from aged CABG patients. In a similar manner, there was an age-dependent decrease of serum TGF-β1 levels in CABG patients (p = 0.0195).

Conclusions

VSMC from aged patients showed a higher degree of cellular senescence and it was associated to a lower TGF-β1 secretion and signaling.

Novel bone morphogenetic protein signaling through Smad2 and Smad3 to regulate cancer progression and development

The bone morphogenetic protein (BMP) signaling pathways have important roles in embryonic development and cellular homeostasis, with aberrant BMP signaling resulting in a broad spectrum of human disease. We report that BMPs unexpectedly signal through the canonical transforming growth factor β (TGF-β)-responsive Smad2 and Smad3. BMP-induced Smad2/3 signaling occurs preferentially in embryonic cells and transformed cells. BMPs signal to Smad2/3 by stimulating complex formation between the BMP-binding TGF-β superfamily receptors, activin receptor-like kinase (ALK)3/6, and the Smad2/3 phosphorylating receptors ALK5/7. BMP signaling through Smad2 mediates, in part, dorsoventral axis patterning in zebrafish embryos, whereas BMP signaling through Smad3 facilitates cancer cell invasion. Consistent with increased BMP-mediated Smad2/3 signaling during cancer progression, Smad1/5 and Smad 2/3 signaling converge in human cancer specimens. Thus, the signaling mechanisms used by BMPs and TGF-β superfamily receptors are broader than previously appreciated.

Quantification of active and total transforming growth factor-β levels in serum and solid organ tissues by bioassay

BACKGROUND

Transforming growth factor-β (TGF-β) is a multi-factorial peptide growth factor that has a vital role in the regulation of cell growth, differentiation, inflammation, and tissue repair. Quantification of biologically active TGF-β levels in tissues is crucial to illustrate mechanisms involved in various physiological and pathological processes, but direct measurement of bioactive TGF-β level in the tissue has been hampered by lack of reliable methods. Here, we introduced mink lung epithelial cell bioassay to quantify both active and total TGF-β levels in serum and protein lysates from solid organs in the mouse model.

FINDINGS

Mink lung epithelial cells were stably transfected with plasminogen activator inhibitor-1 promoter/luciferase construct, in which bioactive TGF-β level was represented by luciferase activity. Serum total TGF-β levels were comparable between the bioassay and enzyme-linked immunosorbent assay (ELISA), but active TGF-β levels measured by ELISA were significantly lower than those obtained by the bioassay. Active and total TGF-β levels in the solid organs including heart, liver, and kidney were also measured. Total TGF-β levels were relatively comparable among these organs, but active TGF-β levels were slightly higher in hearts and kidneys than in livers. Positive luciferase activities in the bioassay were almost completely inhibited by adding pan-TGF-β neutralizing antibodies, suggesting its high specificity to bioactive TGF-β. We also measured myocardial TGF-β levels after myocardial infarction and sham control by the bioassay, and compared the values with those obtained by ELISA. The bioassay demonstrated that both active and total tissue TGF-β levels were significantly higher in post-myocardial infarction than in sham myocardium. ELISA was markedly less sensitive in detecting both active and total TGF-β levels than our bioassay and failed to show any statistically significant difference in TGF-β levels between myocardial infarction and sham myocardium.

CONCLUSIONS

Our data suggested that the bioassay was significantly more sensitive than ELISA in detecting active TGF-β in serum and both active and total TGF-β in solid organ tissues. The bioassay will be useful in investigating TGF-β profile in various solid organs in physiological and pathological conditions.

The complex regulation of TGF-β in cardiovascular disease

Transforming growth factor β (TGF-β1) is a pleiotropic cytokine with many and complex effects in cell and tissue physiology. This is made possible by a very complex and interwoven signaling system, whose regulation continues to be the focus of a growing line of research. This complex regulation translates to a key role in cardiovascular physiology, hemostasis, and the blood–vessel interface. In accordance with this, the TGF-β1 pathway appears to be deregulated in related disorders, such as atherosclerotic vascular disease and myeloproliferative syndromes. It is expected that the growing amount of experimental and clinical research will yield medical advances in the applications of knowledge of the TGF-β1 pathway to diagnosis and therapeutics.

Regulation of a disintegrin and metalloprotease-33 expression by transforming growth factor-β

The asthma susceptibility gene, a disintegrin and metalloprotease-33 (ADAM33), is selectively expressed in mesenchymal cells, and the activity of soluble ADAM33 has been linked to angiogenesis and airway remodeling. Transforming growth factor (TGF)-β is a profibrogenic growth factor, the expression of which is increased in asthma, and recent studies show that it enhances shedding of soluble ADAM33. In this study, we hypothesized that TGF-β also affects ADAM33 expression in bronchial fibroblasts in asthma. Primary fibroblasts were grown from bronchial biopsies from donors with and those without asthma, and treated with TGF-β(2) to induce myofibroblast differentiation. ADAM33 expression was assessed using quantitative RT-PCR and Western blotting. To examine the mechanisms whereby TGF-β(2) affected ADAM33 expression, quantitative methylation-sensitive PCR, chromatin immunoprecipitation, and nuclear accessibility assays were conducted on the ADAM33 promoter. We found that TGF-β(2) caused a time- and concentration-dependent reduction in ADAM33 mRNA expression in normal and asthmatic fibroblasts, affecting levels of splice variants similarly. TGF-β(2) also induced ADAM33 protein turnover and appearance of a cell-associated C-terminal fragment. TGF-β(2) down-regulated ADAM33 mRNA expression by causing chromatin condensation around the ADAM33 promoter with deacetylation of histone H3, demethylation of H3 on lysine-4, and hypermethylation of H3 on lysine-9. However, the methylation status of the ADAM33 promoter did not change. Together, these data suggest that TGF-β(2) suppresses expression of ADAM33 mRNA in normal or asthmatic fibroblasts. This occurs by altering chromatin structure, rather than by gene silencing through DNA methylation as in epithelial cells. This may provide a mechanism for fine regulation of levels of ADAM33 expression in fibroblasts, and may self-limit TGF-β(2)-induced ectodomain shedding of ADAM33.

Can serum fibrosis markers predict medium/large oesophageal varices in patients with liver cirrhosis?

BACKGROUND AND STUDY AIMS

Non-invasive predictors of medium/large oesophageal varices (LOVs) could reduce the number of screening endoscopies. As portal hypertension is a consequence of liver fibrosis, serum fibrosis markers were evaluated together with other variables as possible non-invasive predictors of medium OV/LOV.

PATIENTS AND METHODS

A total of 154 cirrhotic patients with splenomegaly and 30 healthy control subjects were recruited in a prospective study in two gastroenterology centres in Upper Egypt. Clinical parameters assessed included Child-Pugh class, liver size and ascites. Laboratory parameters included complete blood count, liver function tests, and aspartate aminotransferase (AST)/platelet ratio. Transforming growth factor-β(1) (TGF-β(1)), alpha(2) macroglobulin (A(2)M) and hyaluronic acid (HA) were assayed. Ultrasonographic examination was done for assessment of liver span, portal vein diameter and detection of minimal ascites. Oesophageal varices were diagnosed and graded by oesophagogastroduodenoscopy.

RESULTS

Fifty-four patients (35%) had no or small varices and 100 (65%) patients had medium OV/LOV by endoscopy. On multivariate analysis, the independent predictors of medium OV/LOV were the presence of ascites (β=0.258, p=0.047) and serum HA (β=0.449, p=0.009). The receiver operating characteristic curve for HA showed the area under the curve to be 0.916. The sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of HA at a cut-off value of 207μgl(-1) were 94%, 77.8%, 88.7%, 87.5% and 88.3%, respectively.

CONCLUSIONS

The presence of ascites and serum HA level higher than 207μgl(-1) can predict the presence of medium OV/LOV in cirrhotic patients. This would help physicians to identify patients who would most likely benefit from screening endoscopy and thus, reduce costs and discomfort from unnecessary endoscopic procedures.

Biomarkers of hepatic fibrosis, fibrogenesis and genetic pre-disposition pending between fiction and reality

Fibrosis is a frequent, life-threatening complication of most chronic liver diseases. Despite major achievements in the understanding of its pathogenesis, the translation of this knowledge into clinical practice is still limited. In particular, non-invasive and reliable (serum-) biomarkers indicating the activity of fibrogenesis are scarce. Class I biomarkers are defined as serum components having a direct relation to the mechanism of fibrogenesis, either as secreted matrix-related components of activated hepatic stellate cells and fibroblasts or as mediators of extracellular matrix (ECM) synthesis or turnover. They reflect primarily the activity of the fibrogenic process. Many of them, however, proved to be disappointing with regard to sensitivity and speci-ficity. Up to now hyaluronan turned out to be the relative best type I serum marker. Class II biomarkers comprise in general rather simple standard laboratory tests, which are grouped into panels. They fulfil most criteria for detection and staging of fibrosis and to a lesser extent grading of fibrogenic activity. More than 20 scores are currently available, among which Fibrotest™ is the most popular one. However, the diagnostic use of many of these scores is still limited and standardization of the assays is only partially realized. Combining of panel markers in sequential algorithms might increase their diagnostic validity. The translation of genetic pre-disposition biomarkers into clinical practice has not yet started, but some polymorphisms indicate a link to progression and outcome of fibrogenesis. Parallel to serum markers non-invasive physical techniques, for example, transient elastography, are developed, which can be combined with serum tests and profiling of serum proteins and glycans.

Determination of oxidative stress status and concentration of TGF-beta 1 in the blood and saliva of osteoporotic subjects

Preliminary reports indicate the influence of oxidative stress and interleukins, particularly TGF-beta1, in maintenance of bone mass. This study was designed to determine any possible variations of cellular lipid peroxidation, the total antioxidant power, and concentration of TGF-beta1 in blood and saliva of osteoporotic subjects in comparison to healthy people. Blood and saliva samples of 22 osteoporotic women and 22 age-matched healthy women were collected. Samples were analyzed for thiobarbituric acid-reactive substances (TBARS) as a marker of lipid peroxidation, ferric reducing ability (total antioxidant power, TAP), and concentration of TGF-beta1. The blood and saliva TAP (mean +/- SD) of osteoporotic subjects was significantly lower than that of healthy controls (606.65 +/- 119.13 vs. 665.64 +/- 63.73 mmol/L and 560.43 +/- 84.70 vs. 612.05 +/- 81.5, respectively). Blood and saliva TBARS (mean +/- SD) of osteoporotic subjects were significantly higher than those of healthy controls (0.30 +/- 0.04 vs. 0.26 +/- 0.04 and 0.23 +/- 0.03 vs. 0.16 +/- 0.04 micromol/L, respectively). Concentrations of TGF-beta1 (mean +/- SD) in plasma and saliva of osteoporotic subjects were not different in comparison to healthy subjects. Results indicate that persons with osteoporosis have an increased oxidative stress that is not accompanied by changes in TGF-beta1 levels. Use of supplementary antioxidants in osteoporotic patients may be helpful.

Impact of cytokine gene polymorphism on cardiovascular risk in renal transplant recipients

Cardiovascular events are the leading causes of morbidity and mortality in renal transplant recipients (RTR). Given the role of inflammation in atherosclerosis, the contribution of functional polymorphisms of cytokines to cardiovascular diseases (CVD) was assessed in RTR in this study. Polymorphisms of tumour necrosis factor alpha (TNF-alpha) gene [-308 (G-->A), -238 (G-->A)], interleukin-10 (IL-10) gene [-1082(A-->G), -819 (T-->C), -592 (A-->C)], transforming growth factor beta 1 (TGF-beta1) gene [codon 10 (T-->C), codon 25 (G-->C)], carotis intima media thickness (CIMT), left ventricular mass index (LVMI), 24-h ambulatory blood pressure and serum lipoprotein homocysteine level, erythrocyte sedimentation rate, serum C-reactive protein (CRP) and serum fibrinogen level of RTR were determined. Seventy-two RTR (26 cadaveric allograft, 46 living-related allograft, 43 male, 29 female) were included in this study. LVMI were similar in TNF-alpha, IL-10 and TGF-beta1 genotypes. Right and left CIMT were higher in TT genotype (n = 16) than CT (n = 46) and CC (n = 10) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (RCIMT, 7.7 +/- 2.2 mm vs. 7.0 +/- 1.4 mm vs. 5.9 +/- 1.4 mm, P = 0.025; LCIMT, 8.5 +/- 2.5 mm vs. 7.0 +/- 1.3 mm vs. 6.1 +/- 1.2 mm, P = 0.002). Lipoprotein (a) level of TT genotype (35.5 +/- 22.5 mg/dl) was higher than CC (4.1 +/- 2.8 mg/dl) and CT (20.4 +/- 11.2 mg/dl) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (P = 0.037). High producers of cytokine IL-10 -1082 [GG (n = 22) vs. AA + AG (n = 50)] and low producers of TGF-beta codon 25 [GC + CC (n = 17) vs. GG (n = 55)] had lower IMT of carotid artery but the difference did not reach statistical significance (P > 0.05). The CIMT of renal transplant patients was similar in IL-10 (-819, -592) and TNF-alpha (-308, -238) genotypes. No difference was observed in 24-h ambulatory blood pressure levels, serum lipoproteins, plasma homocysteine level, erythrocyte sedimentation rate, serum CRP, serum fibrinogen level in IL-10, TNF-alpha and TGF-beta1 genotypes. Besides the well-known factors, TGF-beta1 gene polymorphisms might play a role in CVD in RTR even at early stages of asymptomatic atherosclerosis.

Inhibitory control of TGF-beta1 on the activation of Rap1, CD11b, and transendothelial migration of leukocytes

Beta2-integrins are a family of dimeric adhesion molecules expressed on leukocytes. Their capacity to bind ligand is regulated by their state of activation. CD11b, an alphaMbeta2 integrin, is implicated in a number of physiological and pathological events such as inflammation, thrombosis, or atherosclerosis. The GTPase Rap1 is essential for its activation and could therefore play a strategic role in the regulation of leukocyte functioning. Because low levels of circulating TGF-beta have been linked with severe atherosclerosis, we have assessed the role of this cytokine in the regulation of Rap1 and CD11b activation in differentiated U937 cells and in human peripheral blood monocytes. TGF-beta1 caused a significant reduction in the expression of CD11b but not in the expression of other integrins tested. More importantly, TGF-beta1 greatly reduced the capacity of PMA or chemokines to activate CD11b and Rap1, a phenomenon paralleled by a loss of the Epac transcript and a reduction in 8-pCPT-2'-O-Me-cAMP-mediated activation of Rap1. This inhibition diminished the capacity of monocytes to migrate across a monolayer of endothelial cells. The inhibitory effect of TGF-beta1 on Rap1 activity may exert a general protective influence against aberrant transendothelial migration, thereby holding inflammatory responses in check.

TGF-? induces novel Lef-1 splice variants through a Smad-independent signaling pathway

The lymphoid enhancer-binding factor (Lef-1) transcription factor is best known for the ability to transduce Wnt signals during development and to mediate excessive Wnt signaling in certain types of cancer. We recently identified and characterized a novel Wnt-like effect of transforming growth factor-beta (TGF-beta) on beta-catenin, the binding partner of Lef-1. Therefore, we sought to determine the effect of TGF-beta on expression of the Lef/T-cell-specific transcription factor (TCF) components of the Wnt pathway. We found that TGF-beta markedly induced Lef-1 mRNA expression in cell lines originating from fetal lung (Mv1Lu) and newborn skin (Balb/MK), tissues that normally express Lef-1 during development. Lef-1 induction was temporally related to but independent of TGF-beta-induced G1 cell cycle arrest. Furthermore, the induction of Lef-1 was independent of both new protein synthesis and Smad-mediated signaling. Using TGF-beta-treated Mv1Lu cells, we identified multiple splice forms of Lef-1, including novel variants that lack both exons 2 and 3. We conclude that the induction of Lef-1 has permissive effects on the well-characterized TGF-beta signal that inhibits c-myc expression and induces a G1 arrest.

Circulating transforming growth factor-beta1, lipoprotein(a) and cellular adhesion molecules in angiographically assessed coronary artery disease

Transforming growth factor-beta1 (TGF-beta1) is involved in different physiological and pathological processes, including atherogenesis. High plasma lipoprotein(a) (Lp(a)) concentration is an established independent risk factor that may interfere with the plasmin-mediated TGF-beta1 activation. Both Lp(a) and TGF-beta1 are thought to influence the expression of cellular adhesion molecules (CAMs), also involved in the process of atherogenesis. Whereas many studies confirmed the association between high plasma Lp(a) levels and coronary artery disease (CAD), conflicting results were obtained in different studies in which the changes of TGF-beta1 and CAM concentrations in CAD patients were investigated. The aim of this case-control study was to explore the association of circulating TGF-beta1, Lp(a) and CAMs (intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin) levels with the occurrence and severity of angiographically assessed coronary artery disease. Plasma TGF-beta1, Lp(a), ICAM-1, VCAM-1 and E-selectin concentrations were measured in 100 patients with angiographically assessed CAD and 100 healthy blood donors matched according to age and gender. Lp(a) and TGF-beta1 were significantly higher in patients than in healthy controls (p < 0.001 and p < 0.01, respectively), but no significant correlation between the TGF-beta1 and Lp(a) values was found. The CAM concentrations obtained in CAD patients did not differ significantly as compared with the corresponding values in the controls. None of the measured parameters were influenced by the severity of CAD.

Mammalian transforming growth factor beta1 activated after ingestion by Anopheles stephensi modulates mosquito immunity

During the process of bloodfeeding by Anopheles stephensi, mammalian latent transforming growth factor beta1 (TGF-beta1) is ingested and activated rapidly in the mosquito midgut. Activation may involve heme and nitric oxide (NO), agents released in the midgut during blood digestion and catalysis of L-arginine oxidation by A. stephensi NO synthase (AsNOS). Active TGF-beta1 persists in the mosquito midgut to extended times postingestion and is recognized by mosquito cells as a cytokine. In a manner analogous to the regulation of vertebrate inducible NO synthase and malaria parasite (Plasmodium) infection in mammals by TGF-beta1, TGF-beta1 regulates AsNOS expression and Plasmodium development in A. stephensi. Together, these observations indicate that, through conserved immunological cross talk, mammalian and mosquito immune systems interface with each other to influence the cycle of Plasmodium development.

Both high intratumoral microvessel density determined using CD105 antibody and elevated plasma levels of CD105 in colorectal cancer patients correlate with poor prognosis

CD105 and its ligand transforming growth factor beta (TGFbeta) are modulators of angiogenesis, which drives tumour growth and metastasis. Tumour microvessel density (MVD) has proven to be an important determinant of prognosis. In this study, we have examined the prognostic value of MVD identified using Mabs to the pan-endothelial marker CD34 and to CD105 in 111 patients with colorectal cancer. The Mab to CD105 preferentially reacts with angiogenic endothelial cells. Of the 111 patients studied, 38 were alive and 73 had died of the disease. The median MVD values counted using anti-CD34 and anti-CD105 were 5 (range 1.40-9.00) and 3.10 (range 0.90-8.00), respectively. Kaplan-Meier survival analysis revealed that only MVD values obtained using CD105 Mab correlated with survival. Patients with a high MVD, above the median (3.10), showed the worst prognosis. A similar outcome was observed when MVD was divided into quartiles. In order to ascertain if this strong expression of CD105 in the tumour vasculature is reflected in patients' plasma, circulating levels of CD105, TGFbeta1 and TGFbeta3 together with the receptor-ligand complexes were quantified in patients with colorectal carcinoma and normal controls. Results showed that except for TGFbeta1, the levels of all other molecules were significantly elevated compared with controls. The levels of CD105 were positively correlated with Dukes' stages. A lower TGFbeta1 level was noted in patients with carcinoma over the controls. Furthermore, TGFbeta3 and CD105/TGFbeta3 complexes were markedly lowered in postoperative compared with preoperative plasma samples. Immunostaining revealed that TGFbeta1 was expressed in cancer cells but TGFbeta3 in the stromal cells, whereas CD105 was exclusively expressed in vascular endothelial cells of tumour blood vessels. In conclusion, this study demonstrates that MVD quantified using a Mab to CD105 is an independent prognostic parameter for survival of patients with colorectal cancer, and that plasma levels of CD105, TGFbeta1, TGFbeta3 and CD105/TGFbeta complexes may be useful markers for assessing disease progression. These data have led us to propose that quantification of these determinants may prove useful to monitor therapeutic efficacy in patients with colorectal cancer, especially those who are being treated with antiangiogenic therapies.

Human platelets produce granulocyte-macrophage colony-stimulating factor and delay eosinophil apoptosis

An association between eosinophils and platelets has been described in several diseases, most notably asthma. Although the mechanisms through which platelets influence eosinophil behavior are not well defined, platelets seem to contribute to the selective accumulation of eosinophils at sites of allergic inflammation by virtue of their ability to produce eosinophil chemotactic factors. We report here for the first time that platelets delay apoptosis, thus enhancing eosinophil survival. A marked inhibition of spontaneous apoptosis was observed using eosinophil:platelet ratios of 1:50, 1:25, 1:10, and 1:5. Moreover, promotion of eosinophil apoptosis by either pronase or dexamethasone was also inhibited greatly in the presence of platelets. The antiapoptotic effect mediated by platelets was dependent on the release of soluble products and was significantly inhibited by neutralizing antibodies directed to GM-CSF. Studies performed by flow cytometry, directed to analyze the cellular source of this cytokine, demonstrated that intracytoplasmic GM-CSF is present in resting platelets. Moreover, GM-CSF was found in platelet supernatants, at concentrations able to prevent eosinophil apoptosis. Our findings support a novel mechanism through which platelets may contribute to eosinophil accumulation at allergic inflammatory sites.

Effect of enalapril and losartan on the events that precede diabetic nephropathy in rats

BACKGROUND

Mesangial cell proliferation, phenotype change, and increased transforming growth factor-beta (TGF-beta) precede mesangial expansion in diabetic rats. Experiments using mesangial cell culture have shown that angiotensin II increases TGF-beta production by these cells. The aim of the present study was to investigate the effect of enalapril and losartan on the events that precede diabetic nephropathy in rats. It was also analyzed if the determination of urinary TGF-beta could be a mean for the evaluation of therapeutic efficacy in this disease.

METHODS

Eighty-two female Wistar rats were made diabetic by intravenous injection of streptozotocin diluted in citrate buffer, and citrate buffer alone was injected into the control group (N = 34). Ten days later, the right kidney was removed. Thirty diabetic rats were treated with enalapril, DMN + E, in drinking water (20 mg/L) and 24 with losartan, DMN + L (50 mg/L). Urinary TGF-beta was determined 90 days after STZ or buffer injection, the animals were killed, and the kidneys were removed for histological and immunohistochemical studies.

RESULTS

The immunostaining for TGF-beta and fibronectin in the cortical tubulointerstitium and glomeruli was higher in untreated diabetic rats (p < 0.001). Treatment with enalapril or losartan reduced this increase. The urinary TGF-beta excretion (pg/mg urinary creatinine) was 48.6 +/- 5.9 in control animals, 603.9 +/- 80.41 in untreated diabetic rats, 279.3 +/- 47.0 in diabetic rats treated with enalapril, and 243.7 +/- 40.0 in rats treated with losartan.

CONCLUSIONS

We concluded that enalapril or losartan treatment can modify events that precede diabetic nephropathy by reducing TGF-beta and fibronectin expression in glomeruli and tubulointerstitium as well as urinary TGF-beta content.

Autologous concentrated platelet-rich plasma (cPRP) for local application in bone regeneration

Platelets are rich in growth factors that may contribute to an accelerated tissue regeneration process. The therapeutic osteogenic effect of local platelet administration probably depends on the amount of growth factors delivered within. To improve platelet-derived factor preparations, the platelets have to be concentrated without loss of the granular growth factor load. An autologous procedure according to the Good Manufacture Practice (GMP) guidelines to prepare a high concentrate from platelet-rich plasma (cPRP) for clinical application in bone regeneration is presented. Platelet-rich plasma (PRP) was generated from the centrifugation supernatant of 250 ml anticoagulated autologous blood. The PRP was then further centrifuged at the day of operation to generate concentrated PRP (cPRP) in 8 ml plasma. The data from 34 patients (9 m, 25 f), ageing from 21 to 71 years (median 50.4) were evaluated. Both, the platelet counts as well as the TGF-beta1 concentrations in the cPRP were found to be 12-fold increased compared to the PRP values. Overall, a 17-fold increase in platelet concentrations was achieved compared to the patients' whole bloods and platelet counts correlated with increased levels of TGF-beta1 within the cPRP. These results give rise to quality control specifications for a safe and cost effective preparation of cPRP. The method has proven to be suitable for blood services to support the needs for treatment in oral and maxillofacial surgery.

Moderate intakes of intact soy protein rich in isoflavones compared with ethanol-extracted soy protein increase HDL but do not influence transforming growth factor beta(1) concentrations and hemostatic risk factors for coronary heart disease in healthy subjects

BACKGROUND

Soybeans contain estrogenic isoflavones that may influence plasma concentrations of transforming growth factor beta(1) (TGF-beta(1)) and plasma lipid and hemostatic risk factors for coronary heart disease.

OBJECTIVE

We compared the effects of moderate intakes of soy protein containing intact phytoestrogens (high-isoflavone diet) and soy protein from which most of the phytoestrogens had been extracted (low-isoflavone diet) on active TGF-beta(1) concentrations and plasma lipid and hemostatic risk factors for coronary heart disease.

DESIGN

A randomized crossover trial was conducted in 22 young, healthy, normolipidemic subjects (5 men and 17 women) who consumed diets providing 56 or 2 mg isoflavones/d for 17 d each with a 25-d washout period between treatments. Fasting blood samples were obtained on days 13 and 14 of each treatment to measure plasma isoflavone, lipid, fibrinogen, and active TGF-beta(1) concentrations and factor VII coagulant and plasminogen activator inhibitor type 1 activities.

RESULTS

Plasma isoflavone concentrations were 100-999 times greater after the high-isoflavone diet than after the low-isoflavone diet (P < 0.05). Plasma HDL-cholesterol and apolipoprotein A-I concentrations were 4% (95% CI: 1%, 8%) and 6% (95% CI: 3%, 10%) higher, respectively, after the high-isoflavone diet than after the low-isoflavone diet (P < 0.01 for both).

CONCLUSION

Compared with soy protein from which most of the phytoestrogens have been extracted, soy protein with intact phytoestrogens increases HDL-cholesterol and apolipoprotein A-I concentrations but does not influence LDL-cholesterol, TGF-beta(1), or fibrinogen concentrations; factor VII coagulant activity; or plasminogen activator inhibitor type 1 activity in normolipidemic, healthy subjects.

Human platelet supernatant promotes proliferation but not differentiation of articular chondrocytes

The objective of the study was to evaluate the growth-promoting activity of human platelet supernatant on primary chondrocytes in comparison with fetal calf serum (FCS) supplemented cell culture medium. Furthermore, the differentiation potential of platelet supernatant was determined in three-dimensional artificial cartilage tissues of bovine articular chondrocytes. Proliferation of articular and nasal septal chondrocytes was assayed by incorporation of BrdU upon stimulation with ten different batches of human platelet supernatant. On bovine articular chondrocytes, all these batches were at least as growth-promoting as FCS. On nasal septal chondrocytes, nine out of ten batches revealed increased or equivalent mitogenic stimulation compared with medium supplemented with FCS. Three-dimensional culture and subsequent histological analysis of matrix formation were used to determine the differentiation properties of platelet supernatant on articular chondrocytes. Human platelet supernatant failed to induce the deposition of typical cartilage matrix components, whereas differentiation and matrix formation were apparent upon cultivation of articular chondrocytes with FCS. Proliferation assays demonstrated that human platelet supernatant stimulates growth of articular and nasal septal chondrocytes; however, platelet supernatant failed to stimulate articular chondrocytes to redifferentiate in three-dimensional chondrocyte cultures. Therefore platelet lysate may be suitable for chondrocyte expansion, but not for maturation of tissue-engineered cartilage.

Increased transforming growth factor-beta(1) circulating levels and production in human monocytes after 3-hydroxy-3-methyl-glutaryl-coenzyme a reductase inhibition with pravastatin

OBJECTIVES

We sought to determine whether inhibition of 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase with pravastatin affects transforming growth factor-beta(1) (TGF-beta(1)) circulating levels and its production in the monocytes of hypercholesterolemic patients.

BACKGROUND

Transforming growth factor-beta(1) is a multifunctional growth factor/cytokine involved in many physiologic and pathologic processes, such as vascular remodeling and atherogenesis. Statins have been reported to have a modulatory role in cytokine expression in the monocytes of hyperlipidemic patients.

METHODS

We evaluated, in a cross-over study design, plasma TGF-beta(1) levels and ex vivo TGF-beta(1) production in the monocytes of hypercholesterolemic patients before and after four to six weeks of lipid-lowering treatment with diet or diet plus 40 mg/day of pravastatin. In addition, isolated blood monocytes were subjected to pravastatin treatment and evaluated for TGF-beta(1) messenger ribonucleic acid (mRNA) expression and TGF-beta(1) in vitro production.

RESULTS

Lipid-lowering treatment significantly decreased total cholesterol and low-density lipoprotein cholesterol plasma levels. Pravastatin, but not a low lipid diet, induced a significant increase in TGF-beta(1) plasma levels (from 1.7 +/- 0.5 ng/ml to 3.1 +/- 1.1 ng/ml, p < 0.001) and in ex vivo monocyte production (from 1.8 +/- 0.8 ng/ml to 3.9 +/- 1.0 ng/ml, p < 0.001). The increase in TGF-beta(1) levels was not related to the changes in the lipid profile observed with pravastatin. An increase of approximately twofold in TGF-beta(1) production and in mRNA expression was also observed after in vitro treatment of human monocytes with pravastatin (5 microM). Co-incubation with mevalonate reversed the in vitro effect of pravastatin.

CONCLUSIONS

3-Hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibition with pravastatin increases TGF-beta(1) plasma levels, as well as monocyte production, in hypercholesterolemic patients. The mevalonate pathway plays a role in the regulation of TGF-beta(1) expression in human monocytes. A possible implication in the biologic and clinical effects of statins can be suggested.

Low TGF-beta1 serum levels are a risk factor for atherosclerosis disease in ESRD patients

BACKGROUND

It is thought that transforming growth factor-beta1 (TGF-beta1) might be a key inhibitor of atherogenesis in non-uremic patients. We evaluated the intra- and post-dialytic serum levels of TGF-beta1 in uremic patients to assess if TGF-beta1 is an independent risk factor for cardiovascular diseases, and if any correlation exists between TGF-beta1 and any yet known atherosclerotic risk factors.

METHODS

We studied 155 patients who were on regular hemodialysis, with or without clinically significant atherosclerotic vascular disease. Forty-one apparently healthy people were enrolled as a control group. TGF-beta1 was evaluated during the midweek dialysis session, at times 0, 30, and 120 minues, at the end of the session, and 3 hours after the session's end. All hitherto known atherosclerotic risk factors also were evaluated. The investigation was performed over a 24-month follow-up.

RESULTS

TGF-beta1 values (mean +/- SD) in dialysis patients were 26.64 +/- 7.0 ng/mL (N=155) compared with 42.31 +/- 6.0 ng/mL in the control group (N=41, P < 0.0001). A weak inverse correlation emerged between TGF-beta1 and age (r=-0.28), TGF-beta1 and lipoprotein(a) [Lp(a); r=-0.35], TGF-beta1 and C-reactive protein (CRP; r=-0.27), and TGF-beta1 and plasminogen activator inhibitor-1 (PAI-1; r=-0.41). TGF-beta1 also correlated with albumin (r=0.31). In the coronary heart disease (CHD) group (N=32) the TGF-beta1 was 26.2 +/- 4.9 ng/mL; in the cerebrovascular disease (CVD) group (N=8) it was 26.7 +/- 3.7 ng/mL and in the peripheral vascular disease (PVD) group (N=9) it was 25.4 +/- 1.7 ng/mL. In dialysis patients with no cardiovascular disease (N=80) TGF-beta1 was 35.1 +/- 6.8 ng/mL (P < 0.0001 vs. CHD, CVD and PVD patients). TGF-beta1 was significantly lower among those patients with triple coronary vessel disease than with the other CHD patients. The Cox analysis demonstrated that a 1 ng/mL reduction in TGF-beta1 concentration was associated with a 9% increase in the relative risk of a cardiovascular event.

CONCLUSIONS

TGF-beta1 was significantly reduced in hemodialysis patients, in particular in those with severe cardiovascular disease. Baseline TGF-beta1, diabetes mellitus and serum albumin levels proved to be the only independent contributors to atherosclerotic risk in dialysis patients.

Involvement of growth factors in the regulation of pubertal mammary growth in cattle

Pubertal mammary growth in heifers is dependent on interactions of many hormones and growth factors of which some are stimulatory while others are inhibitory. Although estrogen and growth hormone (GH) are of primary importance, more recent studies have suggested a role for both systemic and mammary tissue-specific growth factors. Growth factors may act as mediators of estrogen and GH or through specific effects of their own. These growth factors include insulin (INS), IGFs (IGF-I and IGF-II), epidermal growth factor (EGF), FGFs (FGF-1 and FGF-2), TGFs (TGF-alpha and TGF-beta's, amphiregulin (AR), platelets derived growth factor (PDGF), and mammary derived growth factor-1 (MDGF-1). Using mammary epithelial cells derived from prepubertal heifers and cultured in three-dimensional collagen gels as an in vitro model, we have investigated the mitogenic effects of a number of different growth factors (IGF-I, des(1-3) IGF-I, IGF-II, INS, EGF, TGF-alpha, AR, FGF-1, FGF-2, and TGF-beta 1). As expected, IGF-I, des(1-3)IGF-I, IGF-II and INS all stimulated proliferation of mammary cells with des(1-3)IGF-I being the most potent and INS the least potent. The mitogenic effect of IGF-I could be inhibited by both IGFBP-2 and IGFBP-3 showing that these binding proteins modulate the bioactivity of IGF-I in the mammary gland at the cellular level. Regulation of IGF availability by IGFBPs in the extracellular environment therefore is critical for IGF action in the mammary gland. Proliferation of mammary epithelial cells was also stimulated by growth factors of the EGF family, i.e. EGF, TGF-alpha and AR, however, not as much as growth factors from the IGF family. Members of the fibroblast growth factor family showed various mitogenic activities. FGF-1 stimulated DNA synthesis while FGF-2 in concentrations above 10 ng/ml inhibited DNA synthesis. TGF-beta 1 at very low concentrations stimulated proliferation slightly whereas higher concentrations strongly inhibited proliferation of mammary epithelial cells and inhibited mitogenesis induced by growth factors of both the EGF- and IGF family. This shows that TGF-beta 1 is a very potent regulator of pubertal mammary growth.

Plasma transforming growth factor beta(1) and platelet activation: implications for studies in transplant recipients

BACKGROUND

Evidence from animal models supports the hypothesis that dysregulated transforming growth factor beta(1) (TGF beta(1)) expression plays a role in chronic allograft rejection, the progression of diabetic nephropathy and fibrotic glomerulopathies. However, more evidence is required to support this hypothesis in man, and the current literature concerning blood TGF beta(1) levels in clinical studies is highly confused. We have investigated: (i) the hypothesis that the widespread practice of activating clinical samples prior to measurement of TGF beta(1) is detecting the platelet-released pool of TGF beta(1), artefactually generated on venepuncture and unrepresentative of the real circulating in vivo TGF beta(1) pool; and (ii) the effect of different immunosuppressive drugs on apparent TGF beta(1) plasma levels.

METHODS

The effect of two different venepuncture procedures on plasma TGF beta(1) was compared in 10 healthy volunteers, one procedure designed to minimize platelet activation and the other representing standard venepuncture practice in a clinic situation. Blood samples from 52 renal transplant recipients on either cyclosporine or tacrolimus immunosuppression were taken by standard venepuncture to investigate the effect of immunosuppressive drugs on plasma TGF beta(1). Plasma TGF beta(1) and beta thromboglobulin were measured by ELISA.

RESULTS

Among 10 healthy volunteers who underwent two different methods of venepuncture, eight of 10 had undetectable levels of TGF beta(1) (<100 pg/ml) under conditions that minimize platelet activation. In contrast, all 10 paired plasma samples collected by vacutainer had measurable TGF beta(1) (median 7.70 ng/ml, interquartile range 5.87-13.64 ng/ml) following acid/ urea activation. The median beta TG level (a measure of platelet degranulation) was 0.71 microg/ml (interquartile range 0.53-1.19 microg/ml) in the special collections compared with 3.39 microg/ml (interquartile range 2.27-4.33 microg/ml) in the vacutainer samples (P=0.0029). Among 52 allograft recipients there was a significantly higher mean TGF beta(1) level in plasma from patients on cyclosporine therapy compared with patients on tacrolimus (28,090+/-26,860 pg/ml vs 7173+/-10 610 pg/ml, respectively; P<0.002). Mean plasma beta TG levels were also significantly higher during cyclosporine therapy compared with tacrolimus (8.14+/-5.54 microg/ml vs 3.66+/-3.32 microg/ml, respectively; P<0.002). However, when TGF beta(1) values were corrected for the degree of platelet activation (by factoring with beta TG) there was no significant difference between TGF beta(1) levels on cyclosporine or tacrolimus (4117+/-2993 pg/microg beta TG vs 2971+/-658 pg/microg beta TG, respectively; P=0.294).

CONCLUSIONS

To avoid erroneous hypotheses concerning TGF beta(1) and perpetuating confusion in the literature over levels in health and disease, it is imperative that proper internal controls for platelet activation are used. The effects of experimental treatments and drugs on platelet biology must be rigorously controlled when attempting to measure and interpret plasma levels of TGF beta(1) in clinical practice.

Expression of transforming growth factor-beta and tumor necrosis factor-alpha in the plasma and tissues of mice with lupus nephritis

Although elevated levels of transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) have been implicated in renal disease, the tissue distribution and cellular localization of the induced cytokines is not well established. In this study, we investigated the expression of these cytokines during the progression of lupus nephritis in MRL lpr/lpr mice. The concentration of both cytokines increased in the plasma of these animals in an age-dependent manner, and there was an age-dependent induction of TGF-beta and TNF-alpha mRNAs in their kidneys. Although the increase in TGF-beta mRNA was specific for the kidney, the increase in TNF-alpha mRNA was widespread and also could be demonstrated in the liver, lung, and heart. In situ hybridization analysis of renal tissues from the lupus-prone mice localized TGF-beta mRNA to the glomerulus, and more specifically, to resident glomerular cells and inflammatory cells infiltrating periglomerular spaces in the nephritic lesions. The signals for TNF-alpha mRNA were detected only in inflammatory cells and were distributed throughout the nephritic kidney. Plasminogen activator inhibitor-1 (PAI-1) is known to be elevated in the glomeruli of MRL lpr/lpr mice, and intraperitoneal administration of either TGF-beta or TNF-alpha into normal mice markedly induced the expression of this potent inhibitor of fibrinolysis in renal glomerular or tubular cells in vivo. These results suggest that the increased renal expression of both cytokines may contribute to the development of lupus nephritis in this model and raise the possibility that PAI-1 may be involved. The fact that TGF-beta is specifically induced in the kidney whereas TNF-alpha increases in a variety of tissues, supports the hypothesis that the renal specificity of this disorder reflects the abnormal expression of TGF-beta.

The significance of CD105, TGFbeta and CD105/TGFbeta complexes in coronary artery disease

We have quantified levels of CD105, its ligand TGFbeta and receptor-ligand complexes in sera from healthy individuals (n=31), patients with triple vessel disease documented by coronary angiography (TVD; n=36) and patients with chest pain and a positive exercise electrocardiogram but with normal coronary angiogram (NCA; n=30). Both active TGFbeta1 and active plus acid-activatable TGFbeta1 [(a+l)TGFbeta1] were significantly depressed in patients with TVD compared with the other two groups (P</=0.04). CD105 levels in TVD patients were also diminished but elevated in NCA patients. In contrast, patients with TVD had more CD105/TGFbeta1 complex in their sera than the other two groups, suggesting that this may be the reason why TVD patients had low levels of receptor and ligand. TGFbeta3 levels were similar in the three groups, but elevated CD105/TGFbeta3 levels were noted in patients with NCA compared with those with TVD and healthy individuals (P< or =0.02). CD105 was correlated with both active TGFbeta1 and (a+l)TGFbeta1 (P=0.02). CD105 also strongly correlated with TGFbeta3 and CD105/TGFbeta3 complexes (P=0.001 in both cases). The changes in levels of CD105, TGFbeta1 and the receptor-ligand complexes in sera of patients with atherosclerosis suggest that these molecules may be important in the pathobiology of the atherosclerotic disease. Further studies on sequential samples from a larger cohort of patients are needed to define a causal relationship between these molecules and the disease progression.

Measurement of cytokines in clinical samples using immunoassays: problems and pitfalls

With the explosion in interest in cytokines and an increasing understanding of their possible involvement in the pathogenesis of many diseases, the number of studies measuring cytokines in body fluids has increased markedly over the last 5 to 10 years. However, it is readily apparent from the literature that the level of awareness of the many factors that can potentially influence the results obtained is very low. Such factors are likely to contribute considerably to the disparities seen among similar types of study. These include assay properties such as standardization and specificity, type of sample and sample handling, and many biological influences such as age, sex, ethnic background, and diurnal rhythmicity. Clearly, it is not possible to control for all these factors, but a minimum evaluation of assays should be carried out as described, including recovery and parallelity studies using relevant samples and the establishment of reproducibility and normal healthy population levels. An awareness of these factors, which is the purpose of this review, may hopefully lead to an improvement in the quality of studies incorporating the measurement of cytokines in clinical samples and should aid in the interpretation of the data.

Plasma levels of soluble CD105 correlate with metastasis in patients with breast cancer

CD105 (endoglin), a receptor for transforming growth factor (TGF) beta1 and beta3 in vascular endothelial cells, is highly up-regulated in blood vessels of tissues where neovascularisation occurs. It modulates endothelial-mesenchymal signalling and is essential for angiogenesis. Indeed, CD105 knock-out mice die from malvascularisation by 11.5 day p.c. In the present study CD105, TGFbeta1 and CD105/TGFbeta1 complexes were quantified in plasma samples from 77 healthy individuals and 92 patients with early stage breast cancer prior to any treatment. When compared with normal controls, both CD105 and CD105/TGFbeta1 complex levels were significantly elevated in breast cancer patients, whereas TGFbeta1 levels were lower in cancer patients. The most important finding to emerge was that CD105 levels were significantly increased in patients who developed distant metastasis compared with disease-free patients. While there was no significant difference between CD105 levels in controls compared to disease-free patients, it was significantly higher in patients with metastatic disease. Thus patients who had died following local relapse or distant metastases possessed the highest levels of CD105. Neither CD105/TGFbeta1 complex nor TGFbeta1 levels correlated with tumour progression. Our data indicate that CD105 might be a valuable novel angiogenic marker for identifying breast cancer patients who are at high risk of developing metastasis.

Activation of transforming growth factor-beta1 in diabetic kidney disease

Recent data have suggested that certain growth factors and cytokines are involved in the development of diabetic nephropathy. The aim of this study was to investigate whether circulating transforming growth factor beta 1 (TGF-beta1) and tumor necrosis factor alpha (TNF-alpha) are associated with diabetic kidney disease. Serum levels of active and total TGF-beta1 and TNF-alpha were measured in type 2 diabetic patients with nephropathy (n = 23) or without (n = 35) and normoglycemic controls (n = 12). Serum levels of circulating active TGF-beta1 were significantly higher in patients with diabetic nephropathy (0.43 +/- 0.06 ng x mL(-1)) compared with diabetic patients without renal involvement (0.23 +/- 0.03 ng x mL(-1), P = .002) and healthy controls (0.24 +/- 0.03 ng x mL(-1), P= .001), whereas the levels of total (active + latent) TGF-beta1 were not different between the subgroups. Active TGF-beta1 concentrations were correlated with urinary albumin excretion (r = .49, P < .003) and serum creatinine (r= .55, P < .01). Sera from patients with type 2 diabetes contained significantly more TNF-alpha than sera from normoglycemic controls (3.07 +/- 0.24 v 1.65 +/- 0.20 pg x mL(-1), P = .001). However, the comparison of serum TNF-alpha concentrations between microalbuminuric and normoalbuminuric diabetic patients showed no significant difference (3.21 +/- 0.28 v 2.97 +/- 0.34 pg x mL(-1), P = .12). In conclusion, type 2 diabetic patients with diabetic nephropathy exhibit increased activation of TGF-beta1, in serum, suggesting an association between circulating TGF-beta1 activity and the development of renal disease.