The Proteoglycans Biglycan and Decorin Protect Cardiac Cells against Irradiation-Induced Cell Death by Inhibiting Apoptosis.

Radiation-induced heart disease (RIHD), a common side effect of chest irradiation, is a primary cause of mortality among patients surviving thoracic cancer. Thus, the development of novel, clinically applicable cardioprotective agents which can alleviate the harmful effects of irradiation on the heart is of great importance in the field of experimental oncocardiology. Biglycan and decorin are structurally related small leucine-rich proteoglycans which have been reported to exert cardioprotective properties in certain cardiovascular pathologies. Therefore, in the present study we aimed to examine if biglycan or decorin can reduce radiation-induced damage of cardiomyocytes. A single dose of 10 Gray irradiation was applied to induce radiation-induced cell damage in H9c2 cardiomyoblasts, followed by treatment with either biglycan or decorin at various concentrations. Measurement of cell viability revealed that both proteoglycans improved the survival of cardiac cells post-irradiation. The cardiocytoprotective effect of both biglycan and decorin involved the alleviation of radiation-induced proapoptotic mechanisms by retaining the progression of apoptotic membrane blebbing and lowering the number of apoptotic cell nuclei and DNA double-strand breaks. Our findings provide evidence that these natural proteoglycans may exert protection against radiation-induced damage of cardiac cells.

Decorin (DCN) Downregulation Activates Breast Stromal Fibroblasts and Promotes Their Pro-Carcinogenic Effects through the IL-6/STAT3/AUF1 Signaling.

Decorin (DCN), a member of the small leucine-rich proteoglycan gene family, is secreted from stromal fibroblasts with non-cell-autonomous anti-breast-cancer effects. Therefore, in the present study, we sought to elucidate the function of decorin in breast stromal fibroblasts (BSFs). We first showed DCN downregulation in active cancer-associated fibroblasts (CAFs) compared to their adjacent tumor counterpart fibroblasts at both the mRNA and protein levels. Interestingly, breast cancer cells and the recombinant IL-6 protein, both known to activate fibroblasts in vitro, downregulated DCN in BSFs. Moreover, specific DCN knockdown in breast fibroblasts modulated the expression/secretion of several CAF biomarkers and cancer-promoting proteins (α-SMA, FAP- α, SDF-1 and IL-6) and enhanced the invasion/proliferation abilities of these cells through activation of the STAT3/AUF1 signaling. Furthermore, DCN-deficient fibroblasts promoted the epithelial-to-mesenchymal transition and stemness processes in BC cells in a paracrine manner, which increased their resistance to cisplatin. These DCN-deficient fibroblasts also enhanced angiogenesis and orthotopic tumor growth in mice in a paracrine manner. On the other hand, ectopic expression of DCN in CAFs suppressed their active features and their paracrine pro-carcinogenic effects. Together, the present findings indicate that endogenous DCN suppresses the pro-carcinogenic and pro-metastatic effects of breast stromal fibroblasts.

Decorin suppresses stemness and migration potential of malignant peripheral nerve sheath tumor through inhibiting epidermal growth factor receptor signaling.

Cancer stem cells (CSCs) play pivotal roles in the growth, invasion, metastasis, chemo-resistance in malignant peripheral nerve sheath tumor (MPNST). The current characterization of CSCs in MPNST is not complete. Decorin is a critical regulator of microenvironment, but its expression and function in CSCs of MPNST has not been studied. In the current study, Decorin levels and its relationship with lung and liver metastasis were determined in clinical specimens. Decorin expression in CD133-positive or CD44-positive CSCs was analyzed by RT-qPCR on cytospun MPNST cells after flow cytometry-based cell sorting. Decorin-positive cells were separated from Decorin-negative cells in transfected MPNST cell lines using a designed plasmid expressing red fluorescent protein (RFP) under a Decorin promoter. Tumor sphere formation, tumor growth, cell invasion, cell migration, and the resistance to chemotherapy-induced apoptosis were determined on Decorin-positive versus Decorin-negative MPNST cells. In vivo tumor growth was analyzed in mice receiving subcutaneous transplantation of Decorin-positive versus Decorin-negative MPNSTs. We found that Decorin levels were significantly downregulated in MPNST specimens, compared to non-tumorous adjacent tissue. Significantly lower Decorin levels were detected in MPNSTs with lung or liver metastasis compared to those without. Poorer patient survival was detected in Decorin-low MPNST, compared to Decorin-high subjects. More Decorin-negative cells were detected in CD133-positive MPNST cells than CD133-negative MPNST cells, and in CD44-positive MPNST cells than in CD44-negative MPNST cells. Compared to Decorin-positive MPNST cells, Decorin-negative MPNST cells generated significantly more tumor spheres in culture, were more invasive and migratory, and were more resistant to chemotherapy-induced apoptosis, likely due to the inhibition of epidermal growth factor receptor signaling by Decorin. Decorin-negative MPNST cells grew significantly larger tumor in vivo. Thus, depletion of Decorin may occur in CSCs in MPNSTs, serving possibly as a new therapeutic target.

Decorin suppresses tumor lymphangiogenesis: A mechanism to curtail cancer progression.

The complex interplay between malignant cells and the cellular and molecular components of the tumor stroma is a key aspect of cancer growth and development. These tumor-host interactions are often affected by soluble bioactive molecules such as proteoglycans. Decorin, an archetypical small leucine-rich proteoglycan primarily expressed by stromal cells, affects cancer growth in its soluble form by interacting with several receptor tyrosine kinases (RTK). Overall, decorin leads to a context-dependent and protracted cessation of oncogenic RTK activity by attenuating their ability to drive a prosurvival program and to sustain a proangiogenic network. Through an unbiased transcriptomic analysis using deep RNAseq, we identified that decorin down-regulated a cluster of tumor-associated genes involved in lymphatic vessel (LV) development when systemically delivered to mice harboring breast carcinoma allografts. We found that Lyve1 and Podoplanin, two established markers of LVs, were markedly suppressed at both the mRNA and protein levels, and this suppression correlated with a significant reduction in tumor LVs. We further identified that soluble decorin, but not its homologous proteoglycan biglycan, inhibited LV sprouting in an ex vivo 3D model of lymphangiogenesis. Mechanistically, we found that decorin interacted with vascular endothelial growth factor receptor 3 (VEGFR3), the main lymphatic RTK, and its activity was required for the decorin-mediated block of lymphangiogenesis. Finally, we identified that Lyve1 was in part degraded via decorin-evoked autophagy in a nutrient- and energy-independent manner. These findings implicate decorin as a biological factor with antilymphangiogenic activity and provide a potential therapeutic agent for curtailing breast cancer growth and metastasis.

The extracellular matrix differentially directs myoblast motility and differentiation in distinct forms of muscular dystrophy: Dystrophic matrices alter myoblast motility.

Extracellular matrix (ECM) pathologic remodeling underlies many disorders, including muscular dystrophy. Tissue decellularization removes cellular components while leaving behind ECM components. We generated "on-slide" decellularized tissue slices from genetically distinct dystrophic mouse models. The ECM of dystrophin- and sarcoglycan-deficient muscles had marked thrombospondin 4 deposition, while dysferlin-deficient muscle had excess decorin. Annexins A2 and A6 were present on all dystrophic decellularized ECMs, but annexin matrix deposition was excessive in dysferlin-deficient muscular dystrophy. Muscle-directed viral expression of annexin A6 resulted in annexin A6 in the ECM. C2C12 myoblasts seeded onto decellularized matrices displayed differential myoblast mobility and fusion. Dystrophin-deficient decellularized matrices inhibited myoblast mobility, while dysferlin-deficient decellularized matrices enhanced myoblast movement and differentiation. Myoblasts treated with recombinant annexin A6 increased mobility and fusion like that seen on dysferlin-deficient decellularized matrix and demonstrated upregulation of ECM and muscle cell differentiation genes. These findings demonstrate specific fibrotic signatures elicit effects on myoblast activity.

Effect of Vaginal Microecological Alterations on Female Pelvic Organ Prolapse.

INTRODUCTION AND HYPOTHESIS: The objective was to investigate the correlation between endogenous vaginal microecological alterations and female pelvic organ prolapse (POP). METHODS: Patients who underwent vaginal hysterectomy were retrospectively analyzed as the POP group (n = 30) and the non-POP group (n = 30). The vaginal microbial metabolites and enzyme levels were tested using the dry chemoenzymatic method. The mRNA and protein expression were tested using real-time quantitative PCR and immunohistochemistry. SPSS version 25.0 and GraphPad Prism 8.0 were performed for statistical analysis. RESULTS: Compared with the non-POP group, the vaginal pH, H2O2 positivity and leukocyte esterase positivity were higher in patients with POP (all p < 0.05). Further analysis showed that patients with pelvic organ prolapse quantification (POP-Q) stage IV had higher rates of vaginal pH, H2O2 positivity and leukocyte esterase positivity than those with POP-Q stage III. Additionally, the mRNA expression of decorin (DCN), transforming growth factor beta 1 (TGF-ß1), and matrix metalloproteinase-3 (MMP-3) in uterosacral ligament tissues were higher, whereas collagen I and III were lower. Similarly, the positive expression of MMP-3 in uterosacral ligament tissue was significantly upregulated in the POP group compared with the non-POP group (p = 0.035), whereas collagen I (p = 0.004) and collagen III (p = 0.019) in uterosacral ligament tissue were significantly downregulated in the POP group. Correlation analysis revealed that there was a significant correlation between vaginal microecology and collagen metabolism. In addition, MMP-3 correlated negatively with collagen I and collagen III (p = 0.002, r = -0.533; p = 0.002, r = -0.534 respectively), whereas collagen I correlated positively with collagen III (p = 0.001, r = 0.578). CONCLUSIONS: Vaginal microecological dysbiosis affects the occurrence of female POP, which could be considered a novel therapeutic option.

The role of vitamin D receptor in predentin mineralization and dental repair after injury.

Dentin is a permeable and complex tubular composite formed by the mineralization of predentin that mineralization and repair are of considerable clinical interest during dentin homeostasis. The role of Vdr, a receptor of vitamin D, in dentin homeostasis remains unexplored. The aim of the present study was to assess the impact of Vdr on predentin mineralization and dental repair. Vdr-knockout (Vdr-/-) mice models were constructed; histology and immunohistochemistry analyses were conducted for both WT and Vdr-/- mice. The finding revealed a thicker predentin in Vdr-/- mice, characterized by higher expression of biglycan and decorin. A dental injury model was employed to observe tertiary dentin formation in Vdr-/- mice with dental injuries. Results showed that tertiary dentin was harder to form in Vdr-/- mice with dental injury. Over time, heightened pulp invasion was observed at the injury site in Vdr-/- mice. Expression of biglycan and decorin was reduced in the predentin at the injury site in the Vdr-/- mice by immunohistochemistry. Taken together, our results imply that Vdr plays a regulatory role in predentin mineralization and tertiary dentin formation during dentin homeostasis.

Possible involvement of HtrA1 serine protease in the onset of osteoporotic bone extracellular matrix changes.

High-temperature requirement A1 (HtrA1), a multidomain serine protease acting on Extracellular matrix (ECM) rearrangement, is also secreted by osteoblasts and osteoclasts. Recent and conflicting literature highlights HtrA1's role as a controller of bone remodeling, proposing it as a possible target for pathologies with unbalanced bone resorption, like Osteoporosis (OP). To add knowledge on this molecule function in bone physiopathology, here we compared HtrA1 distribution in the ECM of healthy (H) and OP bone tissue, also examining its localization in the sites of new bone formation. HtrA1 was homogeneously expressed in the mature bone ECM of H tissue showing a 55.6 ± 16.4% of the stained area, with a significant (p=0.0001) decrease in OP percentage stained area (21.1 ± 13.1). Moreover, HtrA1 was present in the endosteum and cells involved in osteogenesis, mainly in those "entrapped" in woven bone, whereas osteocytes in mature lamellar bone were negative. Based on our previous observation in OP tissue of a significantly increased expression of Decorin and Osteocalcin, both involved in bone mineralization and remodeling and equally substrates for HtrA1, we speculate that HtrA1 by controlling the proper amount of Decorin and Osteocalcin favors normal bone maturation and mineralization. Besides, we suggest that late-osteoblasts and pre-osteocytes secrete HtrA1 in the adjacent matrix whilst proceeding with their maturation and that HtrA1 expression is further modified during the remodeling from woven to the lamellar bone. Overall, our data suggest HtrA1 as a positive regulator of bone matrix formation and maturation: its reduced expression in mature OP bone, affecting protein content and distribution, could hamper correct bone remodeling and mineralization.

The effects of TGF-ß1 and IFN-α2b on decorin, decorin isoforms and type I collagen in hypertrophic scar dermal fibroblasts.

Hypertrophic scars (HTS) develop from an excessive synthesis of structural proteins like collagen and a decreased expression of proteoglycans such as decorin. Previous research has demonstrated that decorin expression is significantly down-regulated in HTS, deep dermal tissue, and thermally injured tissue, reducing its ability to regulate pro-fibrotic transforming growth factor-beta 1 (TGF-ß1) and normal fibrillogenesis. However, treatment of HTS fibroblasts with interferon-alpha 2b (IFN-α2b) has been shown to reduce excessive collagen synthesis and improve HTS by reducing serum TGF-ß1 levels. The expression of decorin isoforms in HTS is currently unknown and the effects of TGF-ß1 and IFN-α2b on decorin, decorin isoform expression and type 1 collagen are of great interest to our group. Dermal fibroblasts were treated with TGF-ß1 and/or IFN-α2b, for 48 h. The expression and secretion of decorin, decorin isoforms and type 1 collagen were quantified with reverse transcription-quantitative polymerase chain reaction, immunofluorescence staining and enzyme-linked immunosorbent assays. The mRNA expression of decorin and each isoform was significantly reduced in HTS fibroblasts relative to normal skin. TGF-ß1 decreased the mRNA expression of decorin and decorin isoforms, whereas IFN-α2b showed the opposite effect. IFN-α2b significantly inhibited TGF-ß1's effect on the mRNA expression of type I collagen alpha 1 in papillary dermal fibroblasts and overall showed relative effects of inhibiting TGF-ß1. These data support that a further investigation into the structural and functional roles of decorin isoforms in HTS pathogenesis is warranted and that IFN-α2b is an important agent in reducing fibrotic outcomes.

Tissue-targeted and localized AAV5-DCN and AAV5-PEDF combination gene therapy abrogates corneal fibrosis and concurrent neovascularization in rabbit eyes in vivo.

PURPOSE: Corneal fibrosis and neovascularization (CNV) after ocular trauma impairs vision. This study tested therapeutic potential of tissue-targeted adeno-associated virus5 (AAV5) mediated decorin (DCN) and pigment epithelium-derived factor (PEDF) combination genes in vivo. METHODS: Corneal fibrosis and CNV were induced in New Zealand White rabbits via chemical trauma. Gene therapy in stroma was delivered 30-min after chemical-trauma via topical AAV5-DCN and AAV5-PEDF application using a cloning cylinder. Clinical eye examinations and multimodal imaging in live rabbits were performed periodically and corneal tissues were collected 9-day and 15-day post euthanasia. Histological, cellular, and molecular and apoptosis assays were used for efficacy, tolerability, and mechanistic studies. RESULTS: The AAV5-DCN and AAV5-PEDF combination gene therapy significantly reduced corneal fibrosis (p < 0.01 or p < 0.001) and CNV (p < 0.001) in therapy-given (chemical-trauma and AAV5-DCN + AAV5-PEDF) rabbit eyes compared to the no-therapy given eyes (chemical-trauma and AAV5-naked vector). Histopathological analyses demonstrated significantly reduced fibrotic α-smooth muscle actin and endothelial lectin expression in therapy-given corneas compared to no-therapy corneas on day-9 (p < 0.001) and day-15 (p < 0.001). Further, therapy-given corneas showed significantly increased Fas-ligand mRNA levels (p < 0.001) and apoptotic cell death in neovessels (p < 0.001) compared to no-therapy corneas. AAV5 delivered 2.69 × 107 copies of DCN and 2.31 × 107 copies of PEDF genes per µg of DNA. AAV5 vector and delivered DCN and PEDF genes found tolerable to the rabbit eyes and caused no significant toxicity to the cornea. CONCLUSION: The combination AAV5-DCN and AAV5-PEDF topical gene therapy effectively reduces corneal fibrosis and CNV with high tolerability in vivo in rabbits. Additional studies are warranted.

Soluble vascular endothelial glycocalyx proteoglycans as potential therapeutic targets in inflammatory diseases.

Reducing the activity of cytokines and leukocyte extravasation is an emerging therapeutic strategy to limit tissue-damaging inflammatory responses and restore immune homeostasis in inflammatory diseases. Proteoglycans embedded in the vascular endothelial glycocalyx, which regulate the activity of cytokines to restrict the inflammatory response in physiological conditions, are proteolytically cleaved in inflammatory diseases. Here we critically review the potential of proteolytically shed, soluble vascular endothelial glycocalyx proteoglycans to modulate pathological inflammatory responses. Soluble forms of the proteoglycans syndecan-1, syndecan-3 and biglycan exert beneficial anti-inflammatory effects by the removal of chemokines, suppression of proinflammatory cytokine expression and leukocyte migration, and induction of autophagy of proinflammatory M1 macrophages. By contrast, soluble versikine and decorin enhance proinflammatory responses by increasing inflammatory cytokine synthesis and leukocyte migration. Endogenous syndecan-2 and mimecan exert proinflammatory effects, syndecan-4 and perlecan mediate beneficial anti-inflammatory effects and glypican regulates Hh and Wnt signaling pathways involved in systemic inflammatory responses. Taken together, targeting the vascular endothelial glycocalyx-derived, soluble syndecan-1, syndecan-2, syndecan-3, syndecan-4, biglycan, versikine, mimecan, perlecan, glypican and decorin might be a potential therapeutic strategy to suppress overstimulated cytokine and leukocyte responses in inflammatory diseases.

Molecular cues for immune cells from small leucine-rich repeat proteoglycans in their extracellular matrix-associated and free forms.

In this review we highlight emerging immune regulatory functions of lumican, keratocan, fibromodulin, biglycan and decorin, which are members of the small leucine-rich proteoglycans (SLRP) of the extracellular matrix (ECM). These SLRPs have been studied extensively as collagen-fibril regulatory structural components of the skin, cornea, bone and cartilage in homeostasis. However, SLRPs released from a remodeling ECM, or synthesized by activated fibroblasts and immune cells contribute to an ECM-free pool in tissues and circulation, that may have a significant, but poorly understood foot print in inflammation and disease. Their molecular interactions and the signaling networks they influence also require investigations. Here we present studies on the leucine-rich repeat (LRR) motifs of SLRP core proteins, their evolutionary and functional relationships with other LRR pathogen recognition receptors, such as the toll-like receptors (TLRs) to bring some molecular clarity in the immune regulatory functions of SLRPs. We discuss molecular interactions of fragments and intact SLRPs, and how some of these interactions are likely modulated by glycosaminoglycan side chains. We integrate findings on molecular interactions of these SLRPs together with what is known about their presence in circulation and lymph nodes (LN), which are important sites of immune cell regulation. Recent bulk and single cell RNA sequencing studies have identified subsets of stromal reticular cells that express these SLRPs within LNs. An understanding of the cellular source, molecular interactions and signaling consequences will lead to a fundamental understanding of how SLRPs modulate immune responses, and to therapeutic tools based on these SLRPs in the future.

Involvement of small leucine-rich proteoglycans and telocytes in thin and thick human endometrium: immunohistochemical and ultrastructural examination.

Thin endometrium, defined as an endometrial thickness of less than 7 mm during the late follicular phase, is a common cause of frequent cancelation of embryo transfers or recurrent implantation failure during assisted reproductive treatment. Small proteoglycans regulate intracellular signaling cascades by bridging other matrix molecules and tissue elements, affecting cell proliferation, adhesion, migration, and cytokine concentration. The aim of the study is to investigate the role of small leucine-rich proteoglycans in the pathogenesis of thin and thick human endometrium and their differences from normal endometrium in terms of fine structure properties. Normal, thin, and thick endometrial samples were collected, and small leucine-rich proteoglycans (SLRPs), decorin, lumican, biglycan, and fibromodulin immunoreactivities were comparatively analyzed immunohistochemically. The data were compared statistically. Moreover, ultrastructural differences among the groups were evaluated by transmission electron microscopy. The immunoreactivities of decorin, lumican, and biglycan were higher in the thin endometrial glandular epithelium and stroma compared to the normal and thick endometrium (p < .001). Fibromodulin immunoreactivity was also higher in the thin endometrial glandular epithelium than in the normal and thick endometrium (p < .001). However, there was no statistical difference in the stroma among the groups. Ultrastructural features were not profoundly different among cases. Telocytes, however, were not seen in the thin endometrium in contrast to normal and thin endometrial tissues. These findings suggest a possible role of changes in proteoglycan levels in the pathogenesis of thin endometrium.

ECM-engineered electrospun fibers with an immune cascade effect for inhibiting tissue fibrosis.

Tissue regeneration/fibrosis after injury is intricately regulated by the immune cascade reaction and extracellular matrix (ECM). Dysregulated cascade signal could jeopardize tissue homeostasis leading to fibrosis. Bioactive scaffolds mimicking natural ECM microstructure and chemistry could regulate the cascade reaction to achieve tissue regeneration. The current study constructed an ECM-engineered micro/nanofibrous scaffold using self-assembled nanofibrous collagen and decorin (DCN)-loaded microfibers to regulate the immune cascade reaction. The ECM-engineered scaffold promoted anti-inflammatory and pro-regenerative effects, M2 polarization of macrophages, by nanofibrous collagen. The ECM-engineered scaffold could release DCN to inhibit inflammation-associated fibrous angiogenesis. Yet, to prevent excessive M2 activity leading to tissue fibrosis, controlled release of DCN was expected to elicit M1 activity and achieve M1/M2 balance in the repair process. Regulated cascade reaction guided favorable crosstalk between macrophages, endothelial cells and fibroblasts by proximity. Additionally, decorin could also antagonize TGF-ß1 via TGF-ß/Smad3 pathway to suppress fibrotic activity of fibroblasts. Hence, ECM-engineered scaffolds could exert effective regulation of the immune cascade reaction by microstructure and DCN release and achieve the balance between tissue fibrosis and regeneration. STATEMENT OF SIGNIFICANCE: With the incidence of up to 74.6%, failed back surgery syndrome (FBSS) has been a lingering issue in spine surgery, which poses a heavy socio-economic burden to society. Epidural fibrosis is believed to be responsible for the onset of FBSS. Current biomaterial-based strategies treating epidural fibrosis mainly rely on physical barriers and unidirectional suppression of inflammation. Regulation of the immune cascade reaction for inhibiting fibrosis has not been widely studied. Based on the simultaneous regulation of M1/M2 polarization and intercellular crosstalk, the ECM-engineered micro/nanofibrous scaffolds constructed in the current study could exert an immune cascade effect to coordinate tissue regeneration and inhibit fibrosis. This finding makes a significant contribution in the development of a treatment for epidural fibrosis and FBSS.

Hyperprolactinemia modifies extracellular matrix components associated with collagen fibrillogenesis in harderian glands of non- and pregnant female mice.

The harderian gland (HG) is a gland located at the base of the nictating membrane and fills the inferomedial aspect of the orbit in rodents. It is under the influence of the hypothalamic-pituitary-gonadal axis and, because of its hormone receptors, it is a target tissue for prolactin (PRL) and sex steroid hormones (estrogen and progesterone). In humans and murine, the anterior surface of the eyes is protected by a tear film synthesized by glands associated with the eye. In order to understand the endocrine changes caused by hyperprolactinemia in the glands responsible for the formation of the tear film, we used an animal model with metoclopramide-induced hyperprolactinemia (HPRL). Given the evidences that HPRL can lead to a process of cell death and tissue fibrosis, the protein expression of small leucine-rich proteoglycans (SLRPs) was analyzed through immunohistochemistry in the HG of the non- and the pregnant female mice with hyperprolactinemia. The SRLPs are related to collagen fibrillogenesis and they participate in pro-apoptotic signals. Our data revealed that high prolactin levels and changes in steroid hormones (estrogen and progesterone) can lead to an alteration in the amount of collagen, and in the structure of type I and III collagen fibers through changes in the amounts of lumican and decorin, which are responsible for collagen fibrillogenesis. This fact can lead to the impaired functioning of the HG by excessive apoptosis in the HG of the non- and the pregnant female mice with HPRL and especially in the HG of pregnancy-associated hyperprolactinemia.

The Role of Decorin in the Adhesion Process of Treponema Pallidum Subspecies Pallidum to Human Brain Microvascular Endothelial Cells.

Objective: This study aims to investigate the role of decorin in the adhesion process of Treponema pallidum subspecies pallidum (T. pallidum) to human brain microvascular endothelial cells. Methods: The study involved an in vitro experimental design. Western blot analysis was conducted to determine the protein expression level of decorin in the cells. The cells were divided into four groups: Tp group, inactivated Tp group, LPS group, and negative control group. The adhesion of T. pallidum to the cells was analyzed using darkfield microscopy counting and quantitative polymerase chain reaction (qPCR). The cells were divided into four groups based on different preprocessing treatments: control group, decorin group, DCN-siRNA group, and DCN-siRNA+decorin group. Changes in the F-actin of the cells were explored using confocal laser scanning microscopy. The cells were divided into the Tp group, Tp+decorin group, and control group. Results: Western blot analysis showed high expression of decorin in the Tp group and LPS group. Darkfield microscopy counting revealed a significantly higher number of T. pallidum adhered to a single cell in the decorin group compared to the control group. Conversely, the number of adhered T. pallidum was significantly lower in the DCN-siRNA group compared to the control group. qPCR results indicated a considerably higher T. pallidum load in the decorin group compared to the control group. In the Tp group, T. pallidum treatment induced the reorganization of F-actin, while the distribution of F-actin in the Tp+decorin group was comparable to that of the control group. Conclusions: Decorin enhances the adhesion of T. pallidum to human brain microvascular endothelial cells, suggesting that decorin may act as one of the receptors regulating the adhesion of T. pallidum to cells. Furthermore, T. pallidum treatment triggers the rearrangement of F-actin in cells, and decorin plays a protective role in this process.

Proteoglycans in Articular Cartilage and Their Contribution to Chondral Injury and Repair Mechanisms.

Proteoglycans are vital components of the extracellular matrix in articular cartilage, providing biomechanical properties crucial for its proper functioning. They are key players in chondral diseases, specifically in the degradation of the extracellular matrix. Evaluating proteoglycan molecules can serve as a biomarker for joint degradation in osteoarthritis patients, as well as assessing the quality of repaired tissue following different treatment strategies for chondral injuries. Despite ongoing research, understanding osteoarthritis and cartilage repair remains unclear, making the identification of key molecules essential for early diagnosis and effective treatment. This review offers an overview of proteoglycans as primary molecules in articular cartilage. It describes the various types of proteoglycans present in both healthy and damaged cartilage, highlighting their roles. Additionally, the review emphasizes the importance of assessing proteoglycans to evaluate the quality of repaired articular tissue. It concludes by providing a visual and narrative description of aggrecan distribution and presence in healthy cartilage. Proteoglycans, such as aggrecan, biglycan, decorin, perlecan, and versican, significantly contribute to maintaining the health of articular cartilage and the cartilage repair process. Therefore, studying these proteoglycans is vital for early diagnosis, evaluating the quality of repaired cartilage, and assessing treatment effectiveness.

Bifidobacterium adolescentis induces Decorin+ macrophages via TLR2 to suppress colorectal carcinogenesis.

BACKGROUND: The interplay between gut microbiota and tumor microenvironment (TME) in the pathogenesis of colorectal cancer (CRC) is largely unknown. Here, we elucidated the functional role of B. adolescentis and its possible mechanism on the manipulation of Decorin+ macrophages in colorectal cancer. METHODS: The relative abundance of B. adolescentis in tumor or para-tumor tissue of CRC patients was analyzed. The role of B. adolescentis was explored in the CRC animal models. The single cell-RNA sequencing (scRNA-seq) was used to investigate the myeloid cells subsets in TME. The expression level of TLR2/YAP axis and its downstream Decorin in macrophages were tested by Western blot and qRT-PCR. Knockdown of Decorin in Raw264.7 was performed to investigate the effect of Decorin+ macrophages on subcutaneous tumor formation. Multi-immunofluorescence assay examined the number of Decorin+ macrophages on the CRC tissue. RESULTS: We found that the abundance of B. adolescentis was significantly reduced in tumor tissue of CRC patients. Supplementation with B. adolescentis suppressed AOM/DSS-induced tumorigenesis in mice. ScRNA-seq and animal experiment revealed that B. adolescentis increased Decorin+ macrophages. Mechanically, Decorin was activated by TLR2/YAP axis in macrophages. The abundance of B. adolescentis was correlated with the number of Decorin+ macrophages and the expression level of TLR2 in tumor tissue of CRC patients. CONCLUSIONS: These results highlight that B. adolescentis induced Decorin+ macrophages and provide a novel therapeutic target for probiotic-based modulation of immune microenvironment in CRC.

Decorin: a potential therapeutic candidate for ligamentum flavum hypertrophy by antagonizing TGF-ß1.

Ligamentum flavum hypertrophy (LFH) is the main physiological and pathological mechanism of lumbar spinal canal stenosis (LSCS). The specific mechanism for LFH has not been completely clarified. In this study, bioinformatic analysis, human ligamentum flavum (LF) tissues collection and analysis, and in vitro and in vivo experiments were conducted to explore the effect of decorin (DCN) on LFH pathogenesis. Here, we found that TGF-ß1, collagen I, collagen III, α-SMA and fibronectin were significantly upregulated in hypertrophic LF samples. The DCN protein expression in hypertrophic LF samples was higher than that in non-LFH samples, but the difference was not significant. DCN inhibited the expression of TGF-ß1-induced fibrosis-associated proteins in human LF cells, including collagen I, collagen III, α-SMA, and fibronectin. ELISAs showed that TGF-ß1 can upregulate PINP and PIIINP in the cell supernatant, and this effect was inhibited after DCN administration. Mechanistic studies revealed that DCN suppressed TGF-ß1-induced fibrosis by blocking the TGF-ß1/SMAD3 signaling pathway. In addition, DCN ameliorated mechanical stress-induced LFH in vivo. In summary, our findings indicated that DCN ameliorated mechanical stress-induced LFH by antagonizing the TGF-ß1/SMAD3 signaling pathway in vitro and in vivo. These findings imply that DCN is a potential therapeutic candidate for ligamentum flavum hypertrophy.

HBx downregulated decorin and decorin-derived peptides inhibit the proliferation and tumorigenicity of hepatocellular carcinoma cells.

Hepatitis B virus (HBV) is one of the important risk factors in inducing the occurrence and development of liver cancer, while the mechanism has not been fully clarified. In this study, we found decorin (DCN) was significantly reduced in HBV transgenic cell line HepG2-4D14 compared to HepG2. The data from hepatocellular carcinoma (HCC) patients indicated that the level of DCN mRNA was significantly lower in tumor tissues than healthy control and positively correlated with the survival of HCC patients. We revealed that HBV HBx can inhibit the transcription of DCN by blocking p53 activity. Functional analysis demonstrated that overexpression of DCN substantially inhibits the proliferation of HCC cells, while knockdown of DCN enhances the proliferation of HCC cells. It is known that DCN could competitively bind to c-Met to inhibit HGF/c-Met signaling pathway to inhibit the development of HCC. Therefore, we screened the novel antitumor peptides derived from DCN based on the sequence of DCN and the complex structure of HGF/c-Met with virtual screening and identified a set of DCN-derived peptides (DCN-Ps) which may competitively bind to c-Met. We found that 5 of peptides can reduce the proliferation and migration of HepG2 cells significantly. Among them, DCN-P#3 can inhibit the growth of HCC cells both in vitro and in vivo. In conclusion, we discovered that HBV HBx downregulates the expression of DCN, which in turn promotes the proliferation of hepatocytes and the development of HCC. We identified DCN-derived antitumor peptides which provides the candidates for developing novel drugs against HCC.