Dynamic chromatin accessibility and transcriptome changes following PDGF-BB treatment of bone-marrow derived mesenchymal stem cells.

BACKGROUND: Mesenchymal stem cells (MSCs) are multipotent stem cells that are under investigation for use in clinical trials because they are capable of self-renewal and differentiating into different cell types under defined conditions. Nonetheless, the therapeutic effects of MSCs have been constrained by low engraftment rates, cell fusion, and cell survival. Various strategies have been explored to improve the therapeutic efficacy of MSCs, with platelet-derived growth factor (PDGF)-BB emerging as a promising candidate. To enhance our comprehension of the impact of PDGF-BB on the gene expression profile and chromosomal accessibility of MSCs, RNA-sequencing and analysis of chromatin accessibility profiles were conducted on three human primary MSCs in culture, both with and without stimulation by PDGF-BB. RESULTS: Integrative analysis of gene expression and chromatin accessibility demonstrated that PDGF-BB treatment modified the chromatin accessibility landscape, marking regions for activation or repression through the AP-1 family transcription factors TEAD, CEBP, and RUNX2. These changes in AP-1 transcription factor expression, in turn, led to cell proliferation and differentiation potential towards osteoblasts, adipocytes, or chondrocytes. The degree of MSC differentiation varies among cells isolated from different donors. The presence of an enrichment of exosome-related genes is also noted among all the differentially expressed genes. CONCLUSIONS: In conclusion, the observed changes in AP-1 transcription factor expression not only induced cellular proliferation and differentiation, but also revealed variations in the degree of MSC differentiation based on donor-specific differences. Moreover, the enrichment of exosome-related genes among differentially expressed genes suggests a potential significant role for PDGF-BB in facilitating intercellular communication.

Inhibition of p90RSK Ameliorates PDGF-BB-Mediated Phenotypic Change of Vascular Smooth Muscle Cell and Subsequent Hyperplasia of Neointima.

Platelet-derived growth factor type BB (PDGF-BB) regulates vascular smooth muscle cell (VSMC) migration and proliferation, which play critical roles in the development of vascular conditions. p90 ribosomal S6 kinase (p90RSK) can regulate various cellular processes through many different target substrates in several cell types, but the regulatory function of p90RSK on PDGF-BB-mediated cell migration and proliferation and subsequent vascular neointima formation has not yet been extensively examined. In this study, we investigated whether p90RSK inhibition protects VSMCs against PDGF-BB-induced cellular phenotypic changes and the molecular mechanisms underlying the effect of p90RSK inhibition on neointimal hyperplasia in vivo. Pretreatment of cultured primary rat VSMCs with FMK or BI-D1870, which are specific inhibitors of p90RSK, suppressed PDGF-BB-induced phenotypic changes, including migration, proliferation, and extracellular matrix accumulation, in VSMCs. Additionally, FMK and BI-D1870 repressed the PDGF-BB-induced upregulation of cyclin D1 and cyclin-dependent kinase-4 expression. Furthermore, p90RSK inhibition hindered the inhibitory effect of PDGF-BB on Cdk inhibitor p27 expression, indicating that p90RSK may induce VSMC proliferation by regulating the G0/G1 phase. Notably, treatment with FMK resulted in attenuation of neointima development in ligated carotid arteries in mice. The findings imply that p90RSK inhibition mitigates the phenotypic switch and neointimal hyperplasia induced by PDGF-BB.

Histologic Evidence of Oral and Periodontal Regeneration Using Recombinant Human Platelet-Derived Growth Factor.

Human histology provides critical information on the biological potential of various regenerative protocols and biomaterials, which is vital to advancing the field of periodontal regeneration, both in research and clinical practice. Outcomes of histologic studies are particularly valuable when interpreted considering additional evidence available from pre-clinical and clinical studies. One of the best-documented growth factors areproven to have positive effects on a myriad of oral regenerative procedures is recombinant human platelet-derived growth factor-BB (rhPDGF-BB). While a systematic review of clinical studies evaluating rhPDGF in oral regenerative procedures has been recently completed, a review article that focuses on the histologic outcomes is needed. Hence, this communication discusses the histologic effects of rhPDGF-BB on oral and periodontal regenerative procedures, including root coverage and soft tissue augmentation, intrabony defects, furcation defects, peri-implant bone augmentation, and guided bone regeneration. Studies from 1989 to 2022 have been included in this review.

Correlation of platelet-derived growth factor and thromboxane A2 expression with platelet parameters and coagulation indices in chronic altitude sickness patients.

NEW FINDINGS: What is the central question of this study? Is the expression of platelet-derived growth factor (PDGF) and thromboxane A2 (TXA2) elevated in chronic altitude patients, and are they related to thrombosis in chronic mountain sickness? What is the main finding and its importance? The expression of PDGF and TXA2 in both the bone marrow and the peripheral blood of patients with chronic mountain sickness is elevated, and they are considered to be correlated in the mechanism of thrombosis in the chronic mountain sickness. ABSTRACT: The purpose of this study was to evaluate the expression of platelet-derived growth factor (PDGF) and thromboxane A2 (TXA2) along with platelet parameters and coagulation indices in chronic mountain sickness (CMS) patients and healthy individuals on the Qinghai-Tibet Plateau. The levels of PDGF and TXA2 were examined in 22 CMS patients (age, 52.77 ± 9.92 years, haemoglobin, 219 ± 13 g/l) and 25 healthy individuals (age, 47.80 ± 9.78 years, haemoglobin, 146 ± 18 g/l), and the association between platelet parameters and coagulation indices was investigated. Mean platelet volume and fibrinogen degradation product were higher in the CMS compared to the control group (10.58 ± 0.83 vs. 8.92 ± 1.61, 7.50 ± 2.15 vs. 4.40 ± 2.51), platelet count and plateletcrit were lower in the CMS compared to the control group (0.13 (0.80, 0.16) vs. 0.23 (0.18, 0.24), 109 ± 46 vs. 204 ± 86). The levels of PDGF and TXA2 in the bone marrow and peripheral blood of CMS patients were higher (P < 0.01) in comparison to the control group. The two factors had no statistically significant relationship with platelet parameters or coagulation indices (P > 0.159). According to the current findings, platelets in CMS patients were activated, resulting in aberrant coagulation and PDGF and TXA2 expression, which could be due to physiological adjustments to the plateau's high altitude. To summarize, PDGF and TXA2 levels in CMS patients were not correlated with coagulation or platelet parameters, implying that the mechanism behind their increased expression warrants additional investigation.

PDGF/PDGFR: A Possible Molecular Target in Scleroderma Fibrosis.

Systemic sclerosis (SSc) is a clinically heterogeneous disorder of the connective tissue characterized by vascular alterations, immune/inflammatory manifestations, and organ fibrosis. SSc pathogenesis is complex and still poorly understood. Therefore, effective therapies are lacking and remain nonspecific and limited to disease symptoms. In the last few years, many molecular and cellular mediators of SSc fibrosis have been described, providing new potential options for targeted therapies. In this review: (i) we focused on the PDGF/PDGFR pathway as key signaling molecules in the development of tissue fibrosis; (ii) we highlighted the possible role of stimulatory anti-PDGFRα autoantibodies in the pathogenesis of SSc; (iii) we reported the most promising PDGF/PDGFR targeting therapies.

Structural insights into the modulation of PDGF/PDGFR-ß complexation by hyaluronan derivatives.

Angiogenesis is an important physiological process playing a crucial role in wound healing and cancer progression. Vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) are key players in angiogenesis. Based on previous findings regarding the modulation of VEGF activity by glycosaminoglycans (GAG), here we explore the interaction of hyaluronan (HA)-based GAG with PDGF and its receptor PDGFR-ß by applying molecular modeling and dynamics simulations in combination with surface plasmon resonance (SPR). Computational analysis on the interaction of oligo-hyaluronan derivatives with different sulfation pattern and functionalization shows that these GAG interact with PDGF in relevant regions for receptor recognition, and that high sulfation as well as modification with the TAMRA group convey stronger binding. On the other hand, the studied oligo-hyaluronan derivatives are predicted to scarcely recognize PDGFR-ß. SPR results are in line with the computational predictions regarding the binding pattern of HA tetrasaccharide (HA4) derivatives to PDGF and PDGFR-ß. Furthermore, our experimental results also show that the complexation of PDGF to PDGFR-ß can be modulated by HA4 derivatives. The results found open the path for considering HA4 derivatives as potential candidates to be exploited for modulation of the PDGF/PDGFR-ß signaling system in angiogenesis and related disease conditions.

Growth Factor Roles in Soft Tissue Physiology and Pathophysiology.

Repair and healing of injured and diseased tendons has been traditionally fraught with apprehension and difficulties, and often led to rather unsatisfactory results. The burgeoning research field of growth factors has opened new venues for treatment of tendon disorders and injuries, and possibly for treatment of disorders of the aorta and major arteries as well. Several chapters in this volume elucidate the role of transforming growth factor ß (TGFß) in pathogenesis of several heritable disorders affecting soft tissues, such as aorta, cardiac valves, and tendons and ligaments. Several members of the bone morphogenetic group either have been approved by the FDA for treatment of non-healing fractures or have been undergoing intensive clinical and experimental testing for use of healing bone fractures and tendon injuries. Because fibroblast growth factors (FGFs) are involved in embryonic development of tendons and muscles among other tissues and organs, the hope is that applied research on FGF biological effects will lead to the development of some new treatment strategies providing that we can control angiogenicity of these growth factors. The problem, or rather question, regarding practical use of imsulin-like growth factor I (IGF-I) in tendon repair is whether IGF-I acts independently or under the guidance of growth hormone. FGF2 or platelet-derived growth factor (PDGF) alone or in combination with IGF-I stimulates regeneration of periodontal ligament: a matter of importance in Marfan patients with periodontitis. In contrast, vascular endothelial growth factor (VEGF) appears to have rather deleterious effects on experimental tendon healing, perhaps because of its angiogenic activity and stimulation of matrix metalloproteinases-proteases whose increased expression has been documented in a variety of ruptured tendons. Other modalities, such as local administration of platelet-rich plasma (PRP) and/or of mesenchymal stem cells have been explored extensively in tendon healing. Though treatment with PRP and mesenchymal stem cells has met with some success in horses (who experience a lot of tendon injuries and other tendon problems), the use of PRP and mesenchymal stem cells in people has been more problematic and requires more studies before PRP and mesenchymal stem cells can become reliable tools in management of soft tissue injuries and disorders.

Roles of the third Ig-like domain of Necl-5/PVR and the fifth Ig-like domain of the PDGF receptor in its signaling.

The immunoglobulin (Ig)-like cell adhesion molecule nectin-like molecule (Necl)-5/poliovirus receptor is up-regulated in many types of cancer cells and implicated in their abnormally enhanced cell proliferation and movement. We previously showed that Necl-5 cis-interacts with the platelet-derived growth factor (PDGF) receptor ß through the extracellular region and enhances its signaling. Although this cis-interaction does not affect the PDGF-induced tyrosine phosphorylation of the receptor, the interaction of the cytoplasmic region of Necl-5 with sprouty2 and the regulation of its activity are required for the enhancement of the PDGF receptor ß signaling by Necl-5. We investigated here the more detailed mechanism for this cis-interaction of Necl-5 with the PDGF receptor ß. Necl-5 contains three Ig-like domains and the PDGF receptor ß contains five Ig-like domains at their extracellular regions. We showed here that the third Ig-like domain of Necl-5 cis-interacted with the fifth Ig-like domain of the PDGF receptor ß. The recombinant protein of the third Ig-like domain of Necl-5 inhibited the cis-interaction of full-length Necl-5 with the PDGF receptor ß and the PDGF-induced activation of the ERK signaling pathway that was enhanced by Necl-5. These results revealed the novel roles of the third Ig-like domain of Necl-5 and the fifth Ig-like domain of the PDGF receptor ß in its signaling.

MicroRNA-29a inhibits glioblastoma stem cells and tumor growth by regulating the PDGF pathway.

BACKGROUND AND PURPOSE: microRNAs are small noncoding RNAs that play important roles in cancer regulation. In this study, we investigated the expression, functional effects and mechanisms of action of microRNA-29a (miR-29a) in glioblastoma (GBM). METHODS: miR-29a expression levels in GBM cells, stem cells (GSCs) and human tumors as well as normal astrocytes and normal brain were measured by quantitative PCR. miR-29a targets were uncovered by target prediction algorithms, and verified by immunoblotting and 3' UTR reporter assays. The effects of miR-29a on cell proliferation, death, migration and invasion were assessed with cell counting, Annexin V-PE/7AAD flow cytometry, scratch assay and transwell assay, respectively. Orthotopic xenografts were used to determine the effects of miR-29a on tumor growth. RESULTS: Mir-29a was downregulated in human GBM specimens, GSCs and GBM cell lines. Exogenous expression of miR-29a inhibited GSC and GBM cell growth and induced apoptosis. miR-29a also inhibited GBM cell migration and invasion. PDGFC and PDGFA were uncovered and validated as direct targets of miR-29a in GBM. miR-29a downregulated PDGFC and PDGFA expressions at the transcriptional and translational levels. PDGFC and PDGFA expressions in GBM tumors, GSCs, and GBM established cell lines were higher than in normal brain and human astrocytes. Mir-29a expression inhibited orthotopic GBM xenograft growth. CONCLUSIONS: miR-29a is a tumor suppressor miRNA in GBM, where it inhibits cancer stem cells and tumor growth by regulating the PDGF pathway.

Simulating PDGF-Driven Glioma Growth and Invasion in an Anatomically Accurate Brain Domain.

Gliomas are the most common of all primary brain tumors. They are characterized by their diffuse infiltration of the brain tissue and are uniformly fatal, with glioblastoma being the most aggressive form of the disease. In recent years, the over-expression of platelet-derived growth factor (PDGF) has been shown to produce tumors in experimental rodent models that closely resemble this human disease, specifically the proneural subtype of glioblastoma. We have previously modeled this system, focusing on the key attribute of these experimental tumors-the "recruitment" of oligodendroglial progenitor cells (OPCs) to participate in tumor formation by PDGF-expressing retrovirally transduced cells-in one dimension, with spherical symmetry. However, it has been observed that these recruitable progenitor cells are not uniformly distributed throughout the brain and that tumor cells migrate at different rates depending on the material properties in different regions of the brain. Here we model the differential diffusion of PDGF-expressing and recruited cell populations via a system of partial differential equations with spatially variable diffusion coefficients and solve the equations in two spatial dimensions on a mouse brain atlas using a flux-differencing numerical approach. Simulations of our in silico model demonstrate qualitative agreement with the observed tumor distribution in the experimental animal system. Additionally, we show that while there are higher concentrations of OPCs in white matter, the level of recruitment of these plays little role in the appearance of "white matter disease," where the tumor shows a preponderance for white matter. Instead, simulations show that this is largely driven by the ratio of the diffusion rate in white matter as compared to gray. However, this ratio has less effect on the speed of tumor growth than does the degree of OPC recruitment in the tumor. It was observed that tumor simulations with greater degrees of recruitment grow faster and develop more nodular tumors than if there is no recruitment at all, similar to our prior results from implementing our model in one dimension. Combined, these results show that recruitment remains an important consideration in understanding and slowing glioma growth.

The association of maternal lymphatic markers and critical congenital heart defects in the fetus-A population based case-control study.

The objective ot this study was to investigate whether lymphatic markers measured in women during the second trimester are associated with critical congenital heart defects (CCHDs) in offspring. This is a retrospective cohort study of pregnant women who participated in the California Prenatal Screening Program. CCHD data in the offspring was captured by linking birth certificate data with hospital patient discharge records. Second trimester samples were assayed for vascular endothelial growth factor (VEGF), platelet derived growth factor (PDGF) AA/BB, and PDGF AB. Logistic models were used to evaluate the association between lymphatic biomarkers and CCHD. Models were adjusted for other serum biomarkers and maternal characteristics. Results are presented in odds ratios (OR) with 95% confidence intervals (CI). We identified 93 cases with CCHDs and 194 controls without CCHDs. The crude and adjusted OR for log (ln) VEGF was 1.07 (95%CI 0.94-1.22) and 1.08 (95%CI 0.94-1.24), respectively; for ln PDGF AB/BB was 0.93 (95%CI 0.6-1.35) and 0.58 (95%CI 0.32-1.05), respectively. There was a significant association between ln PDFG AA and CCHDs (crude OR 1.83 (95%CI 1.05-3.2); adjusted OR 2.41 (95%CI 1.06-5.44)). Levels of circulating PDGF AA were highest in cases with hypoplastic left heart syndrome (HLHS) (mean 8.78 +/- 1.54 pg/ml). In this study, increased mid-pregnancy maternal serum levels of PDGF AA were associated with CCHDs in offspring. The highest PDGF AA levels were found in mothers of fetuses with HLHS. These findings may be useful in screening for CCHDs and offer insight into their association with nuchal translucency.

Towards next generation maggot debridement therapy: transgenic Lucilia sericata larvae that produce and secrete a human growth factor.

BACKGROUND: Diabetes and its concurrent complications impact a significant proportion of the population of the US and create a large financial burden on the American health care system. FDA-approved maggot debridement therapy (MDT), the application of sterile laboratory-reared Lucilia sericata (green bottle fly) larvae to wounds, is a cost-effective and successful treatment for diabetic foot ulcers and other medical conditions. Human platelet derived growth factor-BB (PDGF-BB) is a secreted dimeric peptide growth factor that binds the PDGF receptor. PDGF-BB stimulates cell proliferation and survival, promotes wound healing, and has been investigated as a possible topical treatment for non-healing wounds. Genetic engineering has allowed for expression and secretion of human growth factors and other proteins in transgenic insects. Here, we present a novel concept in MDT technology that combines the established benefits of MDT with the power of genetic engineering to promote healing. The focus of this study is to create and characterize strains of transgenic L. sericata that express and secrete PDGF-BB at detectable levels in adult hemolymph, whole larval lysate, and maggot excretions/ secretions (ES), with potential for clinical utility in wound healing. RESULTS: We have engineered and confirmed transgene insertion in several strains of L. sericata that express human PDGF-BB. Using a heat-inducible promoter to control the pdgf-b gene, pdgf-b mRNA was detected via semi-quantitative PCR upon heat shock. PDGF-BB protein was also detectable in larval lysates and adult hemolymph but not larval ES. An alternative, tetracycline-repressible pdgf-b system mediated expression of pdgf-b mRNA when maggots were raised on diet that lacked tetracycline. Further, PDGF-BB protein was readily detected in whole larval lysate as well as larval ES. CONCLUSIONS: Here we show robust, inducible expression and production of human PDGF-BB protein from two conditional expression systems in transgenic L. sericata larvae. The tetracycline-repressible system appears to be the most promising as PDGF-BB protein was detectable in larval ES following induction. Our system could potentially be used to deliver a variety of growth factors and anti-microbial peptides to the wound environment with the aim of enhancing wound healing, thereby improving patient outcome in a cost-effective manner.

Synergistic antiproliferative effect of imatinib and adriamycin in platelet-derived growth factor receptor-expressing osteosarcoma cells.

Osteosarcoma (OS) is the most frequent primary solid malignant tumor of bone. Its prognosis remains poor in the substantial proportion of patients who do not respond to chemotherapy and novel therapeutic options are therefore needed. We previously established a mouse model that mimics the aggressive behavior of human OS. Enzyme-linked immunosorbent assay-based screening of such mouse tumor lysates identified platelet-derived growth factor-BB (PDGF-BB) as an abundant soluble factor, the gene for which was expressed dominantly in surrounding non-malignant cells of the tumor, whereas that for the cognate receptor (PDGF receptor ß) was highly expressed in OS cells. Platelet-derived growth factor-BB induced activation of both MEK-ERK and phosphatidylinositol 3-kinase-protein kinase B signaling pathways and promoted survival in OS cells deprived of serum, and these effects were blocked by the PDGF receptor inhibitor imatinib. However, these actions of PDGF-BB and imatinib were mostly masked in the presence of serum. Whereas imatinib alone did not manifest an antitumor effect in mice harboring OS tumors, combined treatment with imatinib and adriamycin exerted a synergistic antiproliferative effect on OS cells in vivo. These results suggest that treatment of OS with imatinib is effective only when cell survival is dependent on PDGF signaling or when imatinib is combined with another therapeutic intervention that renders the tumor cells susceptible to imatinib action, such as by inducing cellular stress.

Deletion of platelet-derived growth factor receptor ß suppresses tumorigenesis in metabolic dysfunction-associated steatohepatitis (MASH) mice with diabetes.

The platelet-derived growth factor (PDGF) family contributes to the progression of steatohepatitis; however, changes in and the characteristics of isoform-specific expression remain unclear. Since diabetes is a major driver of metabolic dysfunction-associated steatohepatitis (MASH), we characterized the mouse model of diabetic MASH (dMASH) by focusing on PDGF signaling. Pdgfa-d expression was markedly higher in hepatic stellate cells among flow-sorted cells in control mice and also increased in dMASH. In contrast, a reanalysis of human single-cell RNA-Seq data showed the distinct distribution of each PDGF isoform with disease progression. Furthermore, inflammation and fibrosis in the liver were less severe in diabetic MASH using tamoxifen-induced PDGF receptor ß (PDGFRß)-deficient mice (KO) than in control dMASH using floxed mice (FL) at 12 weeks old. Despite the absence of tumors, the expression of tumor-related genes was lower in KO than in FL. Tumorigenesis was significantly lower in 20-week-old KO. An Ingenuity Pathway Analysis of differentially expressed miRNA between FL and KO identified functional networks associated with hepatotoxicity and cancer. Therefore, PDGFRß signals play important roles in the progression of steatohepatitis and tumorigenesis in MASH, with the modulation of miRNA expression posited as a potential underlying mechanism.

Characterization of PDGF-Induced Subcellular Calcium Regulation through Calcium Channels in Airway Smooth Muscle Cells by FRET Biosensors.

The homeostasis of cellular calcium is fundamental for many physiological processes, while the calcium levels remain inhomogeneous within cells. During the onset of asthma, epithelial and inflammatory cells secrete platelet-derived growth factor (PDGF), inducing the proliferation and migration of airway smooth muscle (ASM) to the epidermal layer, narrowing the airway. The regulation of ASM cells by PDGF is closely related to the conduction of calcium signals. In this work, we generated subcellular-targeted FRET biosensors to investigate calcium regulation in the different compartments of ASM cells. A PDGF-induced cytoplasmic calcium [Ca2+]C increase was attributed to both extracellular calcium influx and endoplasmic reticulum (ER) calcium [Ca2+]ER release, which was partially regulated by the PLC-IP3R pathway. Interestingly, the removal of the extracellular calcium influx led to inhibited ER calcium release, likely through inhibitory effects on the calcium-dependent activation of the ER ryanodine receptor. The inhibition of the L-type calcium channel on the plasma membrane or the SERCA pump on the ER resulted in both reduced [Ca2+]C and [Ca2+]ER from PDGF stimulation, while IP3R channel inhibition led to reduced [Ca2+]C only. The inhibited SERCA pump caused an immediate [Ca2+]C increase and [Ca2+]ER decrease, indicating active calcium exchange between the cytosol and ER storage in resting cells. PDGF-induced calcium at the outer mitochondrial membrane sub-region showed a similar regulatory response to cytosolic calcium, not influenced by the inhibition of the mitochondrial calcium uniporter channel. Therefore, our work identifies calcium flow pathways among the extracellular medium, cell cytosol, and ER via regulatory calcium channels. Specifically, extracellular calcium flow has an essential function in fully activating ER calcium release.

Long-term stability of frozen platelet-rich plasma under -80 °C storage condition.

Platelet rich plasma (PRP) is increasingly used in various fields of medicine, aiming to regeneration and repair damaged tissues, cells and organs. High concentration of bioactive molecules including growth factors, cytokines and chemokines are the rationale of using PRP. The aim of this study is to analyze the effect of frozen on the levels of growth factors. In our study, PRP samples were isolated from 50 healthy volunteers using the Trima Accel blood cell separator. The concentration of growth factors such as platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF-1) and platelet factor 4 (PF-4) were assessed in fresh PRP and frozen PRP stored at -80 °C for one to twelve months. The study found that count of platelet in all fresh and frozen PRP samples was significantly increased compared to whole blood baseline. There was no significant difference in the concentrations of PDGF-BB, bFGF, VEGF, and PF-4 between fresh and frozen samples. The concentrations of EGF and IGF in Frozen-PRP group were significantly higher than those in Fresh-PRP group. And the storage condition of -80 °C is suitable for PRP, which will not lead to a decrease in growth factors concentration for at least 6 months.

Angiotensin receptor blockers and statins could alleviate atrial fibrosis via regulating platelet-derived growth factor/Rac1/nuclear factor-kappa B Axis.

AIMS: To investigate whether the administration of renin-angiotensin system (RAS) inhibitors and statins could alleviate atrial fibrosis via platelet-derived growth factor (PDGF)/Rac1 /nuclear factor-kappa B (NF-κB) axis. METHODS AND RESULTS: In human left atrium, the degree of atrial fibrosis, as well as the expression levels of PDGF, Rac1 and NF-κB increased 1.5 to 2.9 folds in patients with atrial fibrillation compared to that with sinus rhythm, (P<0.0001). There were strongly positive correlations between angiotensin II (Ang II) or procollagen type III-alpha-1 (COL3A1) with PDGF, Rac1, NF-κB, and among PDGF, Rac1 and NF-κB (all P<0.05). At 3 weeks after the transverse aorta constriction (TAC) operation in rat model and with intervention of irbesartan or/and simvastatin, the collagen volume fraction (CVF) and atrial natriuretic peptide (ANP) values respectively increased 6-folds and 3.5-folds in the TAC group compared to SHAM group (P<0.0001), but these levels decreased by 16% to 63% with following drug intervention (all P<0.0001), the combined treatment was the lowest. Accordingly, the expression levels of PDGF (3-folds), Rac1 (1.6-folds), NF-κB (7-folds) and AngII (12-folds) significantly increased in the TAC group compared to the SHAM group, and these levels were also reduced by 25% to 64% with following drug intervention. The highest reduction could be seen after treatment with irbesartan and simvastatin in combination (all P<0.001).There were strongly positive correlations between AngII or CVF with PDGF, Rac1, NF-κB, and among PDGF, Rac1 and NF-κB (all P<0.05). CONCLUSIONS: Irbesartan or/and simvastatin can improve atrial fibrosis by regulating PDGF/Rac1/NF-κB axis.

Interleukin-11 in idiopathic pulmonary fibrosis: predictive value of prognosis and acute exacerbation.

Background: Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease with a poor prognosis and unknown aetiology. We have recently clarified the prognostic value of the serum platelet-derived growth factor (PDGF) level in patients with IPF. Interleukin (IL)-11 is a member of the IL-6 family, and in vivo and in vitro studies have suggested that it has profibrotic effects in pulmonary fibrosis. In this study, we investigated the predictive value of the serum IL-11 level in patients with IPF for survival and occurrence of acute exacerbation (AE). Methods: This retrospective study included 68 patients with IPF diagnosed according to the 2018 guideline. Serum PDGF levels were measured using the Bio-Plex method and serum IL-11 levels using enzyme-linked immune-sorbent assay. Cytokine production per lung volume was evaluated using the serum cytokine/percent predicted forced vital capacity (%FVC) value. Results: Forty-six patients were male and the median age was 67 years. The serum IL-11/%FVC value was significantly correlated with the percent predicted diffusing capacity of carbon monoxide (ρ=-0.518, P<0.001) and modified Medical Research Council score for shortness of breath (mMRC) (ρ=0.335, P=0.006) by Spearman's rank correlation analysis. Multivariate Cox proportional hazard regression analysis revealed that the serum IL-11/%FVC value was a significant prognostic factor after adjustment for the serum PDGF/%FVC value and other clinical parameters including mMRC and lymphocyte percentage in bronchoalveolar lavage [hazard ratio (HR): 88.540, 95% confidence interval (CI): 1.905-4,115.686, P=0.022]. IL-11/%FVC value was also a significant predictor of AE after adjustment for age and PDGF/%FVC (HR: 1,815.443, 95% CI: 10.49-314,109.219, P=0.004). Conclusions: The serum IL-11/%FVC value was an independent predictor of prognosis and AE occurrence in patients with IPF, and the IL-11 level appeared to show pathophysiologic value in IPF.

Plasma polymerized nanoparticles are a safe platform for direct delivery of growth factor therapy to the injured heart.

Introduction: Heart failure due to myocardial infarction is a progressive and debilitating condition, affecting millions worldwide. Novel treatment strategies are desperately needed to minimise cardiomyocyte damage after myocardial infarction and to promote repair and regeneration of the injured heart muscle. Plasma polymerized nanoparticles (PPN) are a new class of nanocarriers which allow for a facile, one-step functionalization with molecular cargo. Methods: Here, we conjugated platelet-derived growth factor AB (PDGF-AB) to PPN, engineering a stable nano-formulation, as demonstrated by optimal hydrodynamic parameters, including hydrodynamic size distribution, polydisperse index (PDI) and zeta potential, and further demonstrated safety and bioactivity in vitro and in vivo. We delivered PPN-PDGF-AB to human cardiac cells and directly to the injured rodent heart. Results: We found no evidence of cytotoxicity after delivery of PPN or PPN-PDGFAB to cardiomyocytes in vitro, as determined through viability and mitochondrial membrane potential assays. We then measured contractile amplitude of human stem cell derived cardiomyocytes and found no detrimental effect of PPN on cardiomyocyte contractility. We also confirmed that PDGF-AB remains functional when bound to PPN, with PDGF receptor alpha positive human coronary artery vascular smooth muscle cells and cardiac fibroblasts demonstrating migratory and phenotypic responses to PPN-PDGF-AB in the same manner as to unbound PDGF-AB. In our rodent model of PPN-PDGF-AB treatment after myocardial infarction, we found a modest improvement in cardiac function in PPN-PDGF-AB treated hearts compared to those treated with PPN, although this was not accompanied by changes in infarct scar size, scar composition, or border zone vessel density. Discussion: These results demonstrate safety and feasibility of the PPN platform for delivery of therapeutics directly to the myocardium. Future work will optimize PPN-PDGF-AB formulations for systemic delivery, including effective dosage and timing to enhance efficacy and bioavailability, and ultimately improve the therapeutic benefits of PDGF-AB in the treatment of heart failure cause by myocardial infarction.

Follicular dendritic cell differentiation is associated with distinct synovial pathotype signatures in rheumatoid arthritis.

Follicular dendritic cells (FDCs) fundamentally contribute to the formation of synovial ectopic lymphoid-like structures in rheumatoid arthritis (RA) which is associated with poor clinical prognosis. Despite this critical role, regulation of FDC development in the RA synovium and its correlation with synovial pathotype differentiation remained largely unknown. Here, we demonstrate that CNA.42+ FDCs distinctively express the pericyte/fibroblast-associated markers PDGFR-ß, NG2, and Thy-1 in the synovial perivascular space but not in established follicles. In addition, synovial RNA-Seq analysis revealed that expression of the perivascular FDC markers was strongly correlated with PDGF-BB and fibroid synovitis, whereas TNF-α/LT-ß was significantly associated with lymphoid synovitis and expression of CR1, CR2, and FcγRIIB characteristic of mature FDCs in lymphoid follicles. Moreover, PDGF-BB induced CNA.42+ FDC differentiation and CXCL13 secretion from NG2+ synovial pericytes, and together with TNF-α/LT-ß conversely regulated early and late FDC differentiation genes in unsorted RA synovial fibroblasts (RASF) and this was confirmed in flow sorted stromal cell subsets. Furthermore, RASF TNF-αR expression was upregulated by TNF-α/LT-ß and PDGF-BB; and TNF-α/LT-ß-activated RASF retained ICs and induced B cell activation in in vitro germinal center reactions typical of FDCs. Additionally, FDCs trapped peptidyl citrulline, and strongly correlated with IL-6 expression, and plasma cell, B cell, and T cell infiltration of the RA synovium. Moreover, synovial FDCs were significantly associated with RA disease activity and radiographic features of tissue damage. To the best of our knowledge, this is the first report describing the reciprocal interaction between PDGF-BB and TNF-α/LT-ß in synovial FDC development and evolution of RA histological pathotypes. Selective targeting of this interplay could inhibit FDC differentiation and potentially ameliorate RA in clinically severe and drug-resistant patients.