Macrophage inhibitory cytokine-1 promotes angiogenesis by eliciting the GFRAL-mediated endothelial cell signaling

TGF-β Isoforms and GDF-15 in the Development and Progression of Atherosclerosis

The effect of oxidised lipoproteins on the endothelium, monocytes, platelets, and macrophages is a key factor in the initiation and development of atherosclerosis. Antioxidant action, lipoprotein metabolism, and chronic inflammation are the fields of research interest for better understanding the development of the disease. All the fields are related to inflammation and hence to the secretion of cytokines, which are being investigated as potential diagnostic markers for the onset of atherosclerosis. Pathways of vascular damage are crucial for the development of new laboratory readouts. The very early detection of endothelial cell damage associated with the onset of atherosclerosis, allowing the initiation of therapy, remains a major research goal. This article summarises the latest results on the relationship of tumour growth factor beta (TGF-β) isoforms and growth differentiation factor 15 (GDF-15) to the pathogenesis of atherosclerosis: which cells involved in atherosclerosis produce them, which effectors stimulate their synthesis and secretion, how they influence atherosclerosis development, and the relationship between the levels of TGF-β and GDF-15 in the blood and the development and extent of atherosclerosis.

GDF-15 Inhibits ADP-Induced Human Platelet Aggregation through the GFRAL/RET Signaling Complex

Growth differentiation factor-15 (GDF-15) is proposed to be strongly associated with several cardiovascular diseases, such as heart failure and atherosclerosis. Moreover, some recent studies have reported an association between GDF-15 and platelet activation. In this study, we isolated peripheral blood platelets from healthy volunteers and evaluated the effect of GDF-15 on adenosine diphosphate (ADP)-induced platelet activation using the platelet aggregation assay. Subsequently, we detected the expression of GDF-15-related receptors on platelets, including the epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), human epidermal growth factor receptor 3 (HER3), transforming growth factor-beta receptor I (TGF-βRI), transforming growth factor-beta receptor II (TGF-βRII), glial-cell-line-derived neurotrophic factor family receptor α-like (GFRAL), and those rearranged during transfection (RET). Then, we screened for GDF-15 receptors using the GDF-15-related receptor microarray comprising these recombinant proteins. We also performed the immunoprecipitation assay to investigate the interaction between GDF-15 and the receptors on platelets. For the further exploration of signaling pathways, we investigated the effects of GDF-15 on the extracellular signal-regulated kinase (ERK), protein kinase B (AKT), and Janus kinase 2 (JAK2) pathways. We also investigated the effects of GDF-15 on the ERK and AKT pathways and platelet aggregation in the presence or absence of RET agonists or inhibition. Our study revealed that GDF-15 can dose-independently inhibit ADP-induced human platelet aggregation and that the binding partner of GDF-15 on platelets is GFRAL. We also found that GDF-15 inhibits ADP-induced AKT and ERK activation in platelets. Meanwhile, our results revealed that the inhibitory effects of GDF-15 can be mediated by the GFRAL/RET complex. These findings reveal the novel inhibitory mechanism of ADP-induced platelet activation by GDF-15.

Prospective of Pancreatic Cancer Diagnosis Using Cardiac Sensing

Pancreatic carcinoma (Ca Pancreas) is the third leading cause of cancer-related deaths in the world. The malignancies of the pancreas can be diagnosed with the help of various imaging modalities. An endoscopic ultrasound with a tissue biopsy is so far considered to be the gold standard in terms of the detection of Ca Pancreas, especially for lesions <2 mm. However, other methods, like computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI), are also conventionally used. Moreover, newer techniques, like proteomics, radiomics, metabolomics, and artificial intelligence (AI), are slowly being introduced for diagnosing pancreatic cancer. Regardless, it is still a challenge to diagnose pancreatic carcinoma non-invasively at an early stage due to its delayed presentation. Similarly, this also makes it difficult to demonstrate an association between Ca Pancreas and other vital organs of the body, such as the heart. A number of studies have proven a correlation between the heart and pancreatic cancer. The tumor of the pancreas affects the heart at the physiological, as well as the molecular, level. An overexpression of the SMAD4 gene; a disruption in biomolecules, such as IGF, MAPK, and ApoE; and increased CA19-9 markers are a few of the many factors that are noted to affect cardiovascular systems with pancreatic malignancies. A comprehensive review of this correlation will aid researchers in conducting studies to help establish a definite relation between the two organs and discover ways to use it for the early detection of Ca Pancreas.

Serum Concentration of Growth Differentiation Factor 15 and Atherosclerosis among General Older Japanese Individuals with Normal Weight

Growth differentiation factor 15 (GDF-15), which modulates cellular energy balance, is reported to be positively associated with cardiovascular disease. However, there have been no reports about the association between serum GDF-15 concentration and atherosclerosis as evaluated by carotid intima-media thickness (CIMT) among the general population. A cross-sectional study of 536 Japanese individuals aged 60 to 69 years was conducted. To avoid the influence of abnormal cellular energy balance, this study only included participants who had a normal body mass index (BMI) and normal thyroid hormone (free thyroxine and free triiodothyronine) levels. A significant positive association between serum GDF-15 concentration and atherosclerosis was observed. In the sex- and age-adjusted model (Model 1), the odds ratio (OR) (95% confidence interval (CI)) for the logarithmic value of GDF-15 and atherosclerosis was 2.62 (1.67, 5.87). This association remained after adjusting for thyroid function and renal function (Model 2) and further adjusting for known cardiovascular risk factors (Model 3). The corresponding values were 2.61 (1.15, 5.93) for Model 2 and 2.49 (1.08, 5.71) for Model 3, respectively. Serum GDF-15 concentrations could help us to estimate the risk of atherosclerosis by indicating the status of cellular energy balance, which is related to mitochondrial activity among comparative healthy older individuals.

Caspase-4/11 is critical for angiogenesis by repressing Notch1 signaling via inhibiting γ-secretase activity

BACKGROUND AND PURPOSE

Notch1 activation mediated by γ-secretase is critical for angiogenesis. GeneCards database predicted that Caspase-4 (CASP4, with murine ortholog CASP11) interacts with presenilin-1, the catalytic core of γ-secretase. Therefore, we investigated the role of CASP4/11 in angiogenesis.

EXPERIMENTAL APPROACH

In vivo, we studied the role of Casp11 in several angiogenesis mouse models using Casp11 wild-type and knockout mice. In vitro, we detected the effects of CASP4 on endothelial functions and Notch signaling by depleting or overexpressing CASP4 in human umbilical vein endothelial cells (HUVECs). The functional domain responsible for the binding of CASP4 and presenilin-1 was detected by mutagenesis and co-immunoprecipitation.

KEY RESULTS

Casp11 deficiency remarkably impaired adult angiogenesis in ischemic hindlimbs, melanoma xenografts and Matrigel plugs, but not the developmental angiogenesis of retina. Bone marrow transplantation revealed that the pro-angiogenic effect depended on CASP11 derived from non-hematopoietic cells. CASP4 expression was induced by inflammatory factors and CASP4 knockdown decreased cell viability, proliferation, migration and tube formation in HUVECs. Mechanistically, CASP4/11 deficiency increased Notch1 activation in vivo and in vitro, while CASP4 overexpression repressed Notch1 signaling in HUVECs. Moreover, CASP4 knockdown increased γ-secretase activity. γ-Secretase inhibitor DAPT restored the effects of CASP4 siRNA on Notch1 activation and angiogenesis in HUVECs. Notably, the catalytic activity of CASP4/11 was dispensable. Instead, CASP4 directly interacted with presenilin-1 through the caspase recruitment domain (CARD).

CONCLUSIONS AND IMPLICATIONS

These findings reveal a critical role of CASP4/11 in adult angiogenesis and make this molecule a promising therapeutic target for angiogenesis-related diseases in the future.

Macrophage inhibitory cytokine-1 produced by melanoma cells contributes to melanoma tumor growth and metastasis in vivo by enhancing tumor vascularization

Macrophage inhibitory cytokine-1 (MIC-1) has been reported to be elevated in various human cancers including melanoma; however, the function of MIC-1 in cancer remains unclear. In this study, we attempt to clarify the role of MIC-1 in tumor pathogenesis by employing the orthotopic B16F1 melanoma mouse model in which serum MIC-1 levels are positively correlated with tumor size. By stably transfecting a MIC-1 expression construct into B16F1 melanoma cells, we increased the expression and secretion levels of MIC-1. This increase in MIC-1 expression significantly enhanced the growth of tumors derived from B16F1 cells in vivo, despite not affecting in vitro cell growth. The elevated MIC-1 expression in B16F1 cells also resulted in lymph node metastasis in B16F1 tumor-bearing mice, significantly increasing mortality. Interestingly, among small melanoma tumors of similar size, tumors derived from the MIC-1-transfected B16F1 cells exhibited enhanced blood vessel formation compared with those of mock transfectant cells. Also, more MIC-1 was found in well-vascularized tumor regions than in poorly vascularized tumor regions. Moreover, conditioned medium (CM) of the MIC-1-transfected melanoma cells enhanced the angiogenic properties of endothelial cells more than CM of mock transfectant cells. Notably, hypoxic culture conditions forced parental B16F1 cells to secrete more endothelial cell-stimulating factors, among which the function of MIC-1 was confirmed by blocking the effects with an anti-MIC-1 antibody. Taken together, these results suggest that the MIC-1 produced by melanoma cells in response to oxygen deprivation promotes tumor vascularization during melanoma development in vivo, leading to enhanced tumor growth and metastasis.

Titanium Nanoparticles Enhance Production and Suppress Stabilin-1-Mediated Clearance of GDF-15 in Human Primary Macrophages

Macrophages are key innate immune cells that mediate implant acceptance or rejection. Titanium implants degrade over time inside the body, which results in the release of implant wear-off particles. Titanium nanoparticles (TiNPs) favor pro-inflammatory macrophage polarization (M1) and lower tolerogenic activation (M2). GDF-15 regulates immune tolerance and fibrosis and is endocytosed by stabilin-1. How TiNPs affect the healing activities of macrophages and their release of circulating cytokines is an open question in regenerative medicine. In this study for the first time, we identified the transcriptional program induced and suppressed by TiNPs in human pro-inflammatory and healing macrophages. Microarray analysis revealed that TiNPs altered the expression of 5098 genes in M1 (IFN-γ-stimulated) and 4380 genes in M2 (IL-4–stimulated) macrophages. 1980 genes were differentially regulated in both M1 and M2. Affymetrix analysis, confirmed by RT-PCR, demonstrated that TiNPs upregulate expression of GDF-15 and suppress stabilin-1, scavenger receptor of GDF-15. TiNPs also significantly stimulated GDF-15 protein secretion in inflammatory and healing macrophages. Flow cytometry demonstrated, that scavenging activity of stabilin-1 was significantly suppressed by TiNPs. Confocal microscopy analysis showed that TiNPs impair internalization of stabilin-1 ligand acLDL and its transport to the endocytic pathway. Our data demonstrate that TiNPs have a dual effect on the GDF-15/stabilin-1 interaction in macrophage system, by increasing the production of GDF-15 and suppressing stabilin-1-mediated clearance function. In summary, this process can result in a significant increase of GDF-15 in the extracellular space and in circulation leading to unbalanced pro-fibrotic reactions and implant complications.