Decorin

ObjectiveGranzyme B (GrB) is a pro-apoptotic serine protease that contributes to immune-mediated target cell apoptosis. However, during inflammation, GrB accumulates in the extracellular space, retains its activity, and is capable of cleaving extracellular matrix (ECM) proteins. Recent studies have implicated a pathogenic extracellular role for GrB in cardiovascular disease, yet the pathophysiological consequences of extracellular GrB activity remain largely unknown. The objective of this study was to identify proteoglycan (PG) substrates of GrB and examine the ability of GrB to release PG-sequestered TGF-β1 into the extracellular milieu.Methods/resultsThree extracellular GrB PG substrates were identified; decorin, biglycan and betaglycan. As all of these PGs sequester active TGF-β1, cytokine release assays were conducted to establish if GrB-mediated PG cleavage induced TGF-β1 release. Our data confirmed that GrB liberated TGF-β1 from all three substrates as well as from endogenous ECM and this process was inhibited by the GrB inhibitor 3,4-dichloroisocoumarin. The released TGF-β1 retained its activity as indicated by the induction of SMAD-3 phosphorylation in human coronary artery smooth muscle cells.ConclusionIn addition to contributing to ECM degradation and the loss of tissue structural integrity in vivo, increased extracellular GrB activity is also capable of inducing the release of active TGF-β1 from PGs.

Decorin (DCN) is the best characterized member of the extracellular small leucine-rich proteoglycan family present in connective tissues, typically in association with or "decorating" collagen fibrils. It has substantial interest to clinical medicine owing to its antifibrotic, anti-inflammatory, and anticancer effects. Studies on DCN knockout mice have established that a lack of DCN is permissive for tumor development and it is regarded as a tumor suppressor gene. A reduced expression or a total disappearance of DCN has been reported to take place in various forms of human cancers during tumor progression. Furthermore, when used as a therapeutic molecule, DCN has been shown to inhibit tumor progression and metastases in experimental cancer models. DCN affects the biology of various types of cancer by targeting a number of crucial signaling molecules involved in cell growth, survival, metastasis, and angiogenesis. The active sites for the neutralization of different growth factors all reside in different parts of the DCN molecule. An emerging concept that multiple proteases, especially those produced by inflammatory cells, are capable of cleaving DCN suggests that native DCN could be inactivated in a number of pathological inflammatory conditions. In this paper, we review the role of DCN in cancer.

Rationale: Recurrent pregnancy loss (RPL) is a distressing disorder that seriously affects the physical and psychological health of women. RPL is also a sentinel risk marker for future obstetric complications and warrants in-depth investigation. Abnormal polarization and functions of decidual macrophages are associated with RPL; however, the underlying mechanisms remain poorly understood. Methods: Decorin expression, localization, and content in the decidua of women with normal pregnancy (NP) and those with RPL were measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blotting, immunofluorescence, and enzyme-linked immunosorbent assay. The profiles of decidual macrophage subsets were determined using flow cytometry and immunofluorescence in both groups. The correlation between decorin content and the proportion of decidual macrophage subsets in the decidua of early NP women was determined using Pearson analysis. The effects of decorin on the polarization and functions of macrophages were assessed in an in-vitro model of Raw264.7 cells via flow cytometry, western blotting, and RT-qPCR. Moreover, the mitochondrial metabolism in Raw264.7 cells under decorin administration was measured via flow cytometry, western blotting, and immunofluorescence. Thirty-three pregnant mice were included in the in vivo model and underwent different treatments. The embryo abortion rate, macrophage phenotype in the spleen and uteri, and placental development were evaluated using flow cytometry and hematoxylin-eosin staining. Results: Decorin, derived from decidual stromal cells, was highly expressed in the decidua of women with RPL. A positive correlation between decorin content and the proportion of M1-like macrophages was also observed in the decidua of early NP women. In vitro studies showed that decorin treatment inhibited macrophage polarization to M2-like subsets and boosted the inflammatory response, which was related to enhanced anaerobic glycolysis, increased mitochondrial membrane potential and intracellular reactive oxygen species levels, reduced mitochondrial mass, and activation of the myeloid differentiation primary response 88-nuclear factor-κB signaling pathway. Adoptive transfer of decorin-treated bone marrow-derived macrophages in pregnant C57BL/6 mice increased the embryo absorption, accompanied by impaired fetal vascularization. Conclusions: Decidual stromal cell-derived decorin can polarize decidual macrophages toward the M1 phenotype by regulating mitochondrial metabolism, resulting in the occurrence of RPL.

BackgroundCardiac fibroblasts play a key role in extracellular matrix (ECM) remodelling through the synthesis of glycosaminoglycans and proteoglycans (PGs), such as decorin; however, the effects of kisspeptin-10 (KiSS-10) on these components in the heart remain unknown. The aim of this study was to determine the influence of KiSS-10 on glycosaminoglycan and decorin content in human cardiac fibroblast cultures and identify its mechanism.MethodsThe effects of KiSS-10 on glycosaminoglycans and decorin were assessed in human cardiac fibroblast cell line, with or without signalling inhibitor. Glycosaminoglycan levels were determined by the Farndale method, decorin secretion by enzyme-linked immunosorbent assay (ELISA), and decorin expression by quantitative polymerase chain reaction (qPCR).ResultsKiSS-10 treatment caused a dose-dependent increase in glycosaminoglycan content in both cells and medium. This stimulatory effect was abolished by blocking G-protein-coupled receptor 54 (GPR54) with peptide 234 or focal adhesion kinase (FAK) with FAK inhibitor 14 (FAKi). Combining KiSS-10 with phospholipase C inhibitor (D609) did not alter the glycosaminoglycan level compared to KiSS-10 alone. KiSS-10 increased decorin secretion but not expression. Combining peptide 234 with KiSS-10 did not alter media decorin level compared to KiSS-10 alone.ConclusionsKiSS-10 significantly elevated glycosaminoglycan and decorin accumulation in human cardiac fibroblast cultures. This regulatory effect on glycosaminoglycan level appears to be dependent on GPR54 activation and FAK signalling, but not on phospholipase C function. Hence, KiSS-10 may be involved in ECM remodelling in the heart.