To examine the detailed composition of glycosaminoglycans during bovine ovarian follicular development and atresia, the specialized stromal theca layers were separated from the stratified epithelial granulosa cells of healthy (n = 6) and atretic (n = 6) follicles in each of three size ranges: small (3–5 mm), medium (6-9 mm) and large (10 mm or more) (n = 29 animals). Fluorophore-assisted carbohydrate electrophoresis analyses (on a per cell basis) and immunohistochemistry (n = 14) were undertaken. We identified the major disaccharides in thecal layers and the membrana granulosa as chondroitin sulfate-derived ∆uronic acid with 4-sulfated N-acetylgalactosamine and ∆uronic acid with 6-sulfated N-acetylgalactosamine and the heparan sulfate-derived Δuronic acid with N-acetlyglucosamine, with elevated levels in the thecal layers. Increasing follicle size and atresia was associated with increased levels of some disaccharides. We concluded that versican contains 4-sulfated N-acetylgalactosamine and it is the predominant 4-sulfated N-acetylgalactosamine proteoglycan in antral follicles. At least one other non- or 6-sulfated N-acetylgalactosamine proteoglycan(s), which is not decorin or an inter-α-trypsin inhibitor family member, is present in bovine antral follicles and associated with hitherto unknown groups of cells around some larger blood vessels. These areas stained positively for chondroitin/dermatan sulfate epitopes [antibodies 7D4, 3C5, and 4C3], similar to stem cell niches observed in other tissues. The sulfation pattern of heparan sulfate glycosaminoglycans appears uniform across follicles of different sizes and in healthy and atretic follicles. The heparan sulfate products detected in the follicles are likely to be associated with perlecan, collagen XVIII or betaglycan.
► In ovarian follicles the major chondroitin sulfates are ∆uronic acid with 4- or 6-sulfated N-acetylgalactosamine. ► Versican is the predominant 4-sulfated N-acetylgalactosamine proteoglycan in follicles. ► An unidentified non- or 6-sulfated N-acetylgalactosamine proteoglycan is also present in follicles. ► 6-sulfated N-acetylgalactosamine epitopes [antibodies 7D4, 3C5, 4C3 and 3B3(+)] identify a potential stem cell niche. ► The major heparan sulfate are Δuronic acid with N-acetlyglucosamine, and the sulfation is uniform in the follicles examined.
chondroitin sulfate; granulosa cells; hyaluronan; heparan sulfate; inter-α-trypsin inhibitor; thecal cells; versican
Chronic allograft injury (CAI) is a major cause for renal allograft dysfunction and characterized by vasculopathies, tubular atrophy, and fibrosis. We demonstrated that numerous leukocytes interact with vascular endothelial cells of allografts and produce acetylcholine, which contributes to vascular remodeling. The cholinergic system might be a promising target for the development of novel therapies. However, neither the cellular mechanisms nor the acetylcholine receptors involved in CAI are known. Kidney transplantation was performed in the Lewis to Lewis and in the Fischer-334 to Lewis rat strain combination, which is an established experimental model for CAI. Expression of nicotinic and muscarinic acetylcholine receptors mRNA was quantified in renal tissue by real-time RT-PCR on days 9 and 42 after surgery. We detected CHRNA2–7, CHRNA10, CHRNB2, CHRNB4, and CHRM1–3 mRNA in normal kidneys and in renal transplants. In contrast, CHRNA9, CHRM4, and CHRM5 mRNA remained below the threshold of detection. In renal allografts, CHRNA3 and CHRNB4 mRNA expression were dramatically reduced compared to isografts. In conclusion, we demonstrated that most acetylcholine receptor subtypes are expressed by normal and transplanted kidneys. Allograft rejection downmodulates CHRNA3 and CHRNB4 mRNA. The role of different acetylcholine receptor subtypes in the development of CAI remains to be established.
Background. Dimethylarginines are inhibitors of NO synthesis and are involved in the pathogenesis of vascular diseases. In this study, we ask the question if asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) levels change during fatal and reversible acute rejection, and contribute to the pathogenesis of chronic vasculopathy.
Methods. The Dark Agouti to Lewis rat strain combination was used to investigate fatal acute rejection. Fischer 344 kidneys were transplanted to Lewis rats to study reversible acute rejection episode and the process of chronic rejection. Isograft recipients and untreated Lewis rats were used as controls. l-arginine derivatives were determined by HPLC, and ADMA-metabolizing enzymes were studied by quantitative RT–PCR and western blotting.
Results. Renal transplantation transiently increased dimethylarginine levels independent of acute rejection. ADMA plasma levels did not importantly differ between recipients undergoing fatal or reversible acute rejection, whereas SDMA was even lower in recipients of Fisher 344 grafts. In comparison to isograft recipients, ADMA and SDMA levels were slightly elevated during reversible, but not during the process of chronic rejection. Increased dimethylarginine levels, however, did not block NO synthesis. Interestingly, protein methylation, but not ADMA degradation, was increased in allografts.
Conclusions. Our data do not support the concept that renal allografts are protected from fatal rejection by dimethylarginines. Dimethylarginines may play a role in triggering chronic rejection, but a contribution to vascular remodelling itself is improbable. In contrast, differential arginine methylation of yet unknown proteins by PRMT1 may be involved in the pathogenesis of acute and chronic rejection.
ADMA; kidney transplantation; l-arginine; rat; SDMA
Obliterative bronchiolitis (OB) is a major cause of allograft dysfunction after lung transplantation and is thought to result from immunologically mediated airway epithelial destruction and luminal fibrosis. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have been implicated in the regulation of lung inflammation, airway epithelial repair, and extracellular matrix remodeling and therefore may participate in the pathogenesis of OB. The goals of this study were to determine the expression profiles of MMPs and TIMPs and the role of TIMP-1 in the development of airway obliteration using the murine heterotopic tracheal transplant model of OB. We demonstrate the selective induction of MMP-3, MMP-9, MMP-12, and TIMP-1 in a temporally restricted manner in tracheal allografts compared with isografts. In contrast, the expression of MMP-7, TIMP-2, and TIMP-3 was decreased in allografts relative to isografts during the period of graft rejection. TIMP-1 protein localized to epithelial, mesenchymal, and inflammatory cells in the tracheal grafts in a temporally and spatially restricted manner. Using TIMP-1–deficient mice, we demonstrate that the absence of TIMP-1 in the donor trachea or the allograft recipient reduced luminal obliteration and increased re-epithelialization in the allograft compared with wild-type control at 28 d after transplantation. Our findings provide direct evidence that TIMP-1 contributes to the development of airway fibrosis in the heterotopic tracheal transplant model, and suggest a potential role for this proteinase inhibitor in the pathogenesis of OB in patients with lung transplant.
heterotopic tracheal transplant; matrix metalloproteinase; obliterative bronchiolitis; tissue inhibitor of metalloproteinase
To explore the expression of Glycogen synthase kinase 3 beta (GSK-3β) in renal allograft tissue and its significance in the pathogenesis of chronic allograft dysfunction.
Renal allograft biopsy was performed in all of the renal allograft recipients with proteinuria or increased serum creatinine level who came into our hospital from January 2007 to December 2009. Among them 28 cases was diagnosed as chronic allograft dysfunction based on pahtological observation, including 21 males with a mean age of 45 ± 10 years old and 7 females with a mean age of 42 ± 9 years old. The time from kidney transplantation to biopsy were 1-9 (3.5) years. Their serum creatinine level were 206 ± 122 umol/L. Immunohistochemical assay and computer-assisted genuine color image analysis system (imagepro-plus 6.0) were used to detect the expression of GSK-3β in the renal allografts of 28 cases of recipients with chronic allograft dysfunction. Mean area and mean integrated optical density of GSK-3β expression were calculated. The relationship between expression level of GSK-3β and either the grade of inflammatory cell infiltration or interstitial fibrosis/tubular atrophy in renal allograft was analyzed. Five specimens of healthy renal tissue were used as controls.
The expression level of the GSK-3β was significantly increased in the renal allograft tissue of recipients with chronic allograft dysfunction, compared to normal renal tissues, and GSK-3β expression became stronger along with the increasing of the grade of either inflammatory cell infiltration or interstitial fibrosis/tubular atrophy in renal allograft tissue.
There might be a positive correlation between either inflammatory cell infiltration or interstitial fibrosis/tubular atrophy and high GSK-3β expression in renal allograft tissue.
The virtual slide(s) for this article can be found here:
kidney transplantation; GSK-3β; inflammatory cell infiltration
Fibroblast growth factor-18 (FGF-18) has been shown to regulate the growth plate chondrocyte proliferation, hypertrophy and cartilage vascularization necessary for endochondral ossification. The heparan sulfate proteoglycan perlecan is also critical for growth platechondrocyte proliferation. FGF-18 null mice exhibit a skeletal dwarfism similar to that of perlecan null mice. Growth plate perlecan contains chondroitin sulfate (CS) and heparan sulfate (HS) chains and FGF-18 is known to bind to heparin and to heparan sulfate from some sources. We used cationic filtration and immunoprecipitation assays to investigate the binding of FGF-18 to perlecan purified from the growth plate and to recombinant perlecan domains expressed in COS-7 cells. FGF-18 bound to perlecan with a kd of 145 nM. Near saturation, ~103 molecules of FGF-18 bound per molecule of perlecan. At the lower concentrations used, FGF-18 bound with a kd of 27.8 nM. This binding was not significantly altered by chondroitinase nor heparitinase digestion of perlecan, but was substantially and significantly reduced by reduction and alkylation of the perlecan core protein. This indicates that the perlecan core protein (and not the CS nor HS chains) is involved in FGF-18 binding. FGF-18 bound equally to full length perlecan purified from the growth plate and to recombinant domains I-III and III of perlecan. These data indicate that low affinity binding sites for FGF-18 are present in cysteine-rich regions of domain III of perlecan. FGF-18 stimulated 3H-thymidine incorporation in growth plate chondrocyte cultures derived from the lower and upper proliferating zones by 9- and 14-fold, respectively. The addition of perlecan reversed this increased incorporation in the lower proliferating chondrocytes by 74% and in the upper proliferating cells by 37%. These results suggest that perlecan can bind FGF-18 and alter the mitogenic effect of FGF-18 on growth plate chondrocytes.
Binding of chemokines to glycosaminoglycans (GAGs) is classically described as initiating inflammatory cell migration and creating tissue chemokine gradients that direct local leukocyte chemotaxis into damaged or transplanted tissues. While chemokine-receptor binding has been extensively studied during allograft transplantation, effects of glycosaminoglycan (GAG) interactions with chemokines on transplant longevity are less well known. Here we examine the impact of interrupting chemokine-GAG interactions and chemokine-receptor interactions, both locally and systemically, on vascular disease in allografts.
Analysis of GAG or CC chemokine receptor 2 (CCR2) deficiency were coupled with the infusion of viral chemokine modulating proteins (CMPs) in mouse aortic allograft transplants (n = 239 mice). Inflammatory cell invasion and neointimal hyperplasia were significantly reduced in N-deacetylase-N-sulfotransferase-1 (Ndst1f/fTekCre+) heparan sulfate (GAG)-deficient (Ndst1−/−, p<0.044) and CCR2-deficient (Ccr2−/−, p<0.04) donor transplants. Donor tissue GAG or CCR2 deficiency markedly reduced inflammation and vasculopathy, whereas recipient deficiencies did not. Treatment with three CMPs was also investigated; Poxviral M-T1 blocks CC chemokine receptor binding, M-T7 blocks C, CC, and CXC GAG binding, and herpesviral M3 binds receptor and GAG binding for all classes. M-T7 reduced intimal hyperplasia in wild type (WT) (Ccr2+/+, p≤0.003 and Ccr2−/−, p≤0.027) aortic allografts, but not in Ndst1−/− aortic allografts (p = 0.933). M-T1 and M3 inhibited WT (Ccr2+/+ and Ndst1+/+, p≤0.006) allograft vasculopathy, but did not block vasculopathy in Ccr2−/− (p = 0.61). M-T7 treatment alone, even without immunosuppressive drugs, also significantly prolonged survival of renal allograft transplants (p≤0.001).
Interruption of chemokine-GAG interactions, even in the absence of chemokine-receptor blockade, is a highly effective approach to reduction of allograft rejection, reducing vascular inflammation and prolonging allograft survival. Although chemokines direct both local and systemic cell migration, interruption of inherent chemokine responses in the donor tissue unexpectedly had a greater therapeutic impact on allograft vasculopathy.
Heparanase-1 activation, albuminuria, and a decrease in glomerular heparan sulfate (HS) have been described in diabetic nephropathy (DN). Glycosaminoglycan (GAG)-based drugs have been shown to have renoprotective effects in this setting, although recent trials have questioned their clinical effectiveness. Here, we describe the effects of fucosylated chondroitin sulfate (FCS), a novel GAG extracted from a marine echinoderm, in experimentally induced DN compared to a widely used GAG, enoxaparin (ENX).
Diabetes mellitus (DM) was induced by streptozotocin in male Wistar rats divided into three groups: DM (without treatment), FCS (8 mg/kg), and ENX (4 mg/kg), administered subcutaneously. After 12 weeks, we measured blood glucose, blood pressure, albuminuria, and renal function. The kidneys were evaluated for mesangial expansion and collagen content. Immunohistochemical quantifications of macrophages, TGF-β, nestin and immunofluorescence analysis of heparanase-1 and glomerular basement membrane (GBM) HS content was also performed. Gene expression of proteoglycan core proteins and enzymes involved in GAG assembly/degradation were analyzed by TaqMan real-time PCR.
Treatment with GAGs prevented albuminuria and did not affect the glucose level or other functional aspects. The DM group exhibited increased mesangial matrix deposition and tubulointerstitial expansion, and prevention was observed in both GAG groups. TGF-β expression and macrophage infiltration were prevented by the GAG treatments, and podocyte damage was halted. The diabetic milieu resulted in the down-regulation of agrin, perlecan and collagen XVIII mRNAs, along with the expression of enzymes involved in GAG biosynthesis. Treatment with FCS and ENX positively modulated such changes. Heparanase-1 expression was significantly reduced after GAG treatment without affecting the GBM HS content, which was uniformly reduced in all of the diabetic animals.
Our results demonstrate that the administration of FCS prevented several pathological features of ND in rats. This finding should stimulate further research on GAG treatment for this complication of diabetes.
While short-term outcomes in kidney transplantation have improved dramatically, long-term survival remains a major challenge. A key component of long-term, chronic allograft injury in solid organ transplants is arteriosclerosis characterized by vascular neointimal hyperplasia and inflammation. Establishing a model of this disorder would provide a unique tool, not only to identify mechanisms of disease, but also test potential therapeutics for late graft injury. To this end, we utilized a mouse orthotopic renal transplant model in which C57BL/6J (H-2b) recipients were given either a kidney allograft from a completely mismatched Balb/cJ mouse (H-2d), or an isograft from a littermate. A unilateral nephrectomy was performed at the time of transplant followed by a contralateral nephrectomy on post-transplant day seven. Recipients were treated with daily cyclosporine subcutaneously for 14 days and then studied 8 and 12 weeks post transplantation. Renal function was significantly worse in allograft compared to isograft recipients. Moreover, the allografts had significantly more advanced tubulointerstitial fibrosis and profound vascular disease characterized by perivascular leukocytic infiltration and neointimal hyperplasia affecting the intrarenal blood vessels. Thus, we describe a feasible and reproducible murine model of intrarenal transplant arteriosclerosis useful to study allograft vasculopathy.
Perlecan, a ubiquitous heparan sulfate proteoglycan, possesses angiogenic and growth-promoting attributes primarily by acting as a coreceptor for basic fibroblast growth factor (FGF-2). In this report we blocked perlecan expression by using either constitutive CMV-driven or doxycycline- inducible antisense constructs. Growth of colon carcinoma cells was markedly attenuated upon obliteration of perlecan gene expression and these effects correlated with reduced responsiveness to and affinity for mitogenic keratinocyte growth factor (FGF-7). Exogenous perlecan effectively reconstituted the activity of FGF-7 in the perlecan-deficient cells. Moreover, soluble FGF-7 specifically bound immobilized perlecan in a heparan sulfate-independent manner. In both tumor xenografts induced by human colon carcinoma cells and tumor allografts induced by highly invasive mouse melanoma cells, perlecan suppression caused substantial inhibition of tumor growth and neovascularization. Thus, perlecan is a potent inducer of tumor growth and angiogenesis in vivo and therapeutic interventions targeting this key modulator of tumor progression may improve cancer treatment.
Proteoglycan core proteins are linked to four different classes of linear sugar chains referred to as glycosaminoglycans. Heparan sulfate constitutes one of these classes of glycosaminoglycans, and has been shown to be important in developmental processes as well as disease. We designed a low-density gene expression array to identify expression levels of heparan sulfate biosynthetic enzymes and proteoglycan core proteins in the aorta of late stage embryos (E18.5) and adult mice (12 weeks). Significant changes were found in mRNA expression of proteoglycan core proteins syndecan, glypican, decorin, perlecan, and versican from development to adulthood (n=8, p<0.05). Immunohistochemistry revealed a striking localization of both decorin and perlecan staining to the subendothelium in adult vessels, which differed from consistent staining of the endothelium, smooth muscle, and adventitia in development. Significant differences were also identified in the expression of the heparan sulfate modifying enzymes, glururonyl C5 epimerase, 2-O and 6-O sulfotransferases, and N-deacetylase/N sulfotransferases 1–3 (n =8, p<0.05). In conclusion, proteoglycan core proteins and heparan sulfate biosynthetic enzymes in the aorta undergo significant changes in their expression from development to adulthood. These findings may have important biological significance in the specific cell-defined roles of proteoglycan and heparan sulfate related targets in vascular development, maintenance, and response to various perturbations.
Heparan sulfate; Proteoglycan; Gene expression; O-sulfotransferase; N-sulfotransferase
Perlecan (Hspg2) is a heparan sulfate proteoglycan expressed in basement membranes and cartilage. Perlecan deficiency (Hspg2−/−) in mice and humans causes lethal chondrodysplasia, which indicates that perlecan is essential for cartilage development. However, the function of perlecan in endochondral ossification is not clear. Here, we report the critical role of perlecan in VEGF signaling and angiogenesis in growth plate formation. The Hspg2−/− growth plate was significantly wider but shorter due to severely impaired endochondral bone formation. Hypertrophic chondrocytes were differentiated in Hspg2−/− growth plates; however, removal of the hypertrophic matrix and calcified cartilage was inhibited. Although the expression of MMP-13, CTGF, and VEGFA was significantly upregulated in Hspg2−/− growth plates, vascular invasion into the hypertrophic zone was impaired, which resulted in an almost complete lack of bone marrow and trabecular bone. We demonstrated that cartilage perlecan promoted activation of VEGF/VEGFR by binding to the VEGFR of endothelial cells. Expression of the perlecan transgene specific to the cartilage of Hspg2−/− mice rescued their perinatal lethality and growth plate abnormalities, and vascularization into the growth plate was restored, indicating that perlecan in the growth plate, not in endothelial cells, is critical in this process. These results suggest that perlecan in cartilage is required for activating VEGFR signaling of endothelial cells for vascular invasion and for osteoblast migration into the growth plate. Thus, perlecan in cartilage plays a critical role in endochondral bone formation by promoting angiogenesis essential for cartilage matrix remodeling and subsequent endochondral bone formation.
Perlecan; Endochondral bone formation; Growth plate; Vascular invasion; VEGF signaling
To date, adult lymphangiogenesis is not well understood. In this study we describe the evolution of lymphatic capillaries in regenerating skin and correlate lymphatic migration and organization with the expression of matrix metalloproteinases (MMPs), immune cells, the growth factors VEGF-A and VEGF-C, and the heparan sulfate proteogylcan perlecan, a key component of basement membrane. We show that while lymphatic endothelial cells (LECs) migrate and organize unidirectionally, in the direction of interstitial fluid flow, they do not sprout into the region but rather migrate as single cells that later join together into vessels. Furthermore, in a modified “shunted flow” version of the model, infiltrated LECs fail to organize into functional vessels, indicating that interstitial fluid flow is necessary for lymphatic organization. Perlecan expression on new lymphatic vessels was only observed after vessel organization was complete and also appeared first in the distal region, consistent with the directionality of lymphatic migration and organization. VEGF-C expression peaked at the initiation of lymphangiogenesis but was reduced to lower levels throughout organization and maturation. In mice lacking MMP-9, lymphatics regenerated normally, suggesting that MMP-9 is not required for lymphangiogenesis, at least in mouse skin. This study thus characterizes the process of adult lymphangiogenesis and differentiates it from sprouting blood angiogenesis, verifies its dependence on interstitial fluid flow for vessel organization, and correlates its temporal evolution with those of relevant environmental factors.
lymphatic; vasculogenesis; interstitial fluid flow; matrix metalloproteinase-9; perlecan
Perlecan is a large multi-domain proteoglycan which is essential for normal cartilage development. In this study perlecan was localized in the pericellular matrix of hypertrophic chondrocytes in developing human cartilage rudiments. Perlecan immunopurified from medium conditioned by cultured human fetal chondrocytes was found to be substituted with heparan sulfate (HS), chondroitin sulfate (CS) and keratan sulfate (KS). Ligand and carbohydrate engagement (LACE) assays demonstrated that immunopurified chondrocyte-derived perlecan formed HS dependent ternary complexes with fibroblast growth factors (FGF) 2 and either FGFR receptors (FGFRs) 1 or 3, however these complexes were not biologically active in the BaF32 cell system. Chondrocyte-derived perlecan also formed HS dependent ternary complexes with FGF18 and FGFR3. The proliferation of BaF32 cells expressing FGFR3 was promoted by chondrocyte-derived perlecan in the presence of FGF18 and this activity was reduced by digesting the HS with either heparinase III or mammalian heparanase. These data suggest that FGF2 and 18 bind to discrete structures on the HS chains attached to chondrocyte-derived perlecan which modulate the growth factor activities. The presence and activity of mammalian heparanase may be important in the turnover of HS and subsequent signaling required for the establishment and maintenance of functional osteo-chondral junctions in long bone growth.
perlecan; heparan sulfate; fibroblast growth factor; fibroblast growth factor receptor; heparanase
Osteocytes project long, slender processes throughout the mineralized matrix of bone, where they connect and communicate with effector cells. The interconnected cellular projections form the functional lacunocanalicular system, allowing fluid to pass for cell-to-cell communication and nutrient and waste exchange. Prevention of mineralization in the pericellular space of the lacunocanalicular pericellular space is crucial for uninhibited interstitial fluid movement. Factors contributing to the ability of the pericellular space of the lacunocanalicular system to remain open and unmineralized are unclear. Immunofluorescence and immunogold localization by transmission electron microscopy demonstrated perlecan/Hspg2 signal localized to the osteocyte lacunocanalicular system of cortical bone, and this proteoglycan was found in the pericellular space of the lacunocanalicular system. In this study we examined osteocyte lacunocanalicular morphology in mice deficient in the large heparan sulfate proteoglycan perlecan/Hspg2 in this tissue. Ultrastructural measurements with electron microscopy of perlecan/Hspg2-deficient mice demonstrated diminished osteocyte canalicular pericellular area, resulting from a reduction in the total canalicular area. Additionally, perlecan/Hspg2-deficient mice showed decreased canalicular density and a reduced number of transverse tethering elements per canaliculus. These data indicated that perlecan/Hspg2 contributed to the integrity of the osteocyte lacunocanalicular system by maintaining the size of the pericellular space, an essential task to promote uninhibited interstitial fluid movement in this mechanosensitive environment. This work thus identified a new barrier function for perlecan/Hspg2 in murine cortical bone. © 2011 American Society for Bone and Mineral Research.
OSTEOCYTE; PERLECAN/HSPG2; MECHANOSENSING; HEPARAN SULFATE; LACUNOCANALICULAR SYSTEM; CORTICAL BONE
Female donors and recipients have increased risk of acute rejection and subsequent chronic allograft nephropathy (CAN), especially when cyclosporine A (CsA) is used. Decreased renal nitric oxide (NO) production is associated with chronic kidney disease. In the present study, we investigated the impact of gender, CsA dose and renal NO synthase (NOS) on CAN.Kidneys from male and female F344 rats were transplanted into same-sex Lewis allograft or F344 isograft recipients and recipient rats were treated with 1.5 or 3 mg/kg per day CsA for 10 days. Grafts were removed at 22 weeks post-transplantation. Normal two-kidney F344 rats were investigated as age-matched controls.Low-dose CsA was associated with accelerated CAN in female rats compared with male rats; however, with high-dose CsA, allograft females had similar pathology/function to allograft males. Isograft females (similar to isograft males) had no graft failure and only slightly, albeit significantly, greater injury than age-matched controls. Isograft females had higher renal cortical neuronal (n) NOS but lower medullary endothelial (e) NOS than isograft males. There was no difference in renal eNOS and nNOS between allograft groups.In conclusion, 1.5 mg/kg per day CsA is not sufficient to prevent early graft loss in females. When the dose of CsA is doubled, allograft females and males have similar post-transplant survival. Renal NOS expression was unremarkable in any transplant group.
cyclosporine; immunosuppression; kidney transplantation; sex difference
The expression of a specific set of genes controls the different structures of heparan sulfate proteoglycans (HSPGs), which are involved in the growth, invasion and metastatic properties of cancerous cells. The purpose of this study is to increase knowledge of HSPG alterations in breast cancer.
Twenty-three infiltrating ductal adenocarcinomas (IDCs), both metastatic and non-metastatic were studied. A transcriptomic approach to the structure of heparan sulfate (HS) chains was used, employing qPCR to analyze both the expression of the enzymes involved in their biosynthesis and editing, as well as the proteoglycan core proteins. Since some of these proteoglycans can also carry chondroitin sulfate chains, we extended the study to include the genes involved in the biosynthesis of these glycosaminoglycans. Histochemical techniques were also used to analyze tissular expression of particular genes showing significant expression differences, of potential interest.
No significant change in transcription was detected in approximately 70% of analyzed genes. However, 13 demonstrated changes in both tumor types (40% showing more intense deregulation in the metastatic), while 5 genes showed changes only in non-metastatic tumors. Changes were related to 3 core proteins: overexpression of syndecan-1 and underexpression of glypican-3 and perlecan. HS synthesis was affected by lower levels of some 3-O-sulfotransferase transcripts, the expression of NDST4 and, only in non metastatic tumors, higher levels of extracellular sulfatases. Furthermore, the expression of chondroitin sulfate also was considerably affected, involving both the synthesis of the saccharidic chains and sulfations at all locations. However, the pro-metastatic enzyme heparanase did not exhibit significant changes in mRNA expression, although in metastatic tumors it appeared related to increased levels of the most stable form of mRNA. Finally, the expression of heparanase 2, which displays anti-metastatic features, experienced a strong deregulation in all patients analyzed.
IDCs show alterations in the expression of HSPG genes; principally the expression and localization of proteoglycans and the sulfation patterns of glycosaminoglycan chains, depending on the metastatic nature of the tumor. In addition, the anti-proliferative molecule heparanase 2 experiences strong deregulation, thus highlighting it as a potentially interesting diagnostic factor.
Heparan sulfate; Breast cancer; Proteoglycan; Glycosaminoglycan; Invasive ductal carcinoma
Versican/proteoglycan-mesenchymal (PG-M) is a large chondroitin sulfate (CS) proteoglycan of the extracellular matrix (ECM) that is constitutively expressed in adult tissues such as dermis and blood vessels. It serves as a structural macromolecule of the ECM, while in embryonic tissue it is transiently expressed at high levels and regulates cell adhesion, migration, proliferation, and differentiation. Knock-in mouse embryonic (Cspg2Δ3/Δ3) fibroblasts whose versican lack the A subdomain of the G1 domain exhibit low proliferation rates and acquire senescence. It was suspected that chondroitin sulfate on versican core protein would be altered when the A subdomain was disrupted, so fibroblasts were made from homozygous Cspg2Δ3/Δ3 mouse embryos to investigate the hypothesis. Analysis of the resulting versican deposition demonstrated that the total versican deposited in the Cspg2Δ3/Δ3 fibroblasts culture was approximately 50% of that of the wild type (WT), while the versican deposited in the ECM of Cspg2Δ3/Δ3 fibroblasts culture was 35% of that of the WT, demonstrating the lower capacity of mutant (Cspg2Δ3/Δ3) versican deposited in the ECM. The analysis of CS expression in the Cspg2Δ3/Δ3 fibroblasts culture compared with wild-type fibroblasts showed that the composition of the non-sulfate chondroitin sulfate isomer on the versican core protein increased in the cell layer but decreased in the culture medium. Interestingly, chondroitin sulfate E isomer was found in the culture medium. The amount of CS in the Cspg2Δ3/Δ3 cell layer of fibroblasts with mutant versican was dramatically decreased, contrasted to the amount in the culture medium, which increased. It was concluded that the disruption of the A subdomain of the versican molecule leads to lowering of the amount of versican deposited in the ECM and the alteration of the composition and content of CS on the versican molecule.
Chondroitin sulfate; extracellular matrix; mouse embryonic fibroblasts; versican
Transplantation of growth-permissive cells or tissues was used to bridge a lesion cavity and induce axonal growth in experimental spinal cord injury (SCI). Axonal interactions between host and transplant may be affected by upregulation of inhibitory chondroitin sulfate proteoglycans (CSPGs) following various transplantation strategies. The extent of axonal growth and functional recovery after transplantation of embryonic spinal cord tissue decreases in adult compared to neonatal host. We hypothesized that CSPGs contribute to the decrease in the extent to which transplant supports axonal remodeling and functional recovery. Expression of CSPGs increased after overhemisection SCI in adult rats but not in neonates. Embryonic spinal cord transplant was surrounded by CSPGs deposited in host cord, and the interface between host and transplant seemed to contain a large amount of CSPGs. Intrathecally delivered chondroitinase ABC (C'ase) improved recovery of distal forelimb usage and skilled motor behavior after C4 overhemisection injury and transplantation in adults. This behavioral recovery was accompanied by an increased amount of raphespinal axons growing into the transplant, and raphespinal innervation to the cervical motor region was promoted by C'ase plus transplant. Moreover, C'ase increased the number of transplanted neurons that grew axons to the host cervical enlargement, suggesting that degradation of CSPGs supports remodeling not only of host axons but also axons from transplanted neurons. Our results suggest that CSPGs constitute an inhibitory barrier to prevent axonal interactions between host and transplant in adults, and degradation of the inhibitory barrier can potentiate transplant-mediated axonal remodeling and functional recovery after SCI.
chondroitin sulfate proteoglycans; transplantation; spinal cord injury; axonal remodeling; functional recovery; regeneration
Background. Tissue transglutaminase (TG2), a cross-linking enzyme, modulates deposition of extracellular matrix protein in renal fibrosis. This study aimed to examine TG2 and its cross-link product ε(γ-glutamyl)-lysine in the Fisher-Lewis rat renal transplantation (RTx) model of chronic allograft nephropathy (CAN). Materials and Methods. Left renal grafts from male Fisher and Lewis were transplanted into Lewis rats, generating allografts and isografts, respectively. Blood pressure, renal function, and proteinuria were monitored for up to 52 weeks. At termination, CAN was assessed in the renal tissue by light and electron microscopy, TG2 and ε(γ-glutamyl)-lysine by immunofluorescence, and the urinary ε(γ-glutamyl)-lysine by high performance liquid chromatography. Results. Compared to the isograft, the allografts were hypertensive, proteinuric, and uraemic and developed CAN. Extracellular TG2 (glomerulus: 64.55 ± 17.61 versus 2.11 ± 0.17, P < 0.001; interstitium: 13.72 ± 1.62 versus 3.19 ± 0.44, P < 0.001), ε(γ-glutamyl)-lysine (glomerulus: 21.74 ± 2.71 versus 1.98 ± 0.37, P < 0.01; interstitium: 37.96 ± 17.06 versus 0.42 ± 0.11, P < 0.05), TG2 enzyme activity (1.09 ± 0.13 versus 0.41 ± 0.03 nmol/h/mg protein, P < 0.05), TG2 mRNA (20-fold rise), and urinary ε(γ-glutamyl)-lysine (534.2 ± 198.4 nmol/24 h versus 57.2 ± 4.1 nmol/24 h, P < 0.05) levels were significantly elevated in the allografts and showed a positive linear correlation with tubulointerstitial fibrosis. Conclusion. CAN was associated with upregulation of renal TG2 pathway, which has a potential for pharmacological intervention. The elevated urinary ε(γ-glutamyl)-lysine, measured for the first time in RTx, is a potential biomarker of CAN.
Lymphatic dysfunction in lymphedema results in chronic accumulation of interstitial fluid and life-long tissue swelling. In the absence of restored lymphatic drainage via adequate lymphangiogenesis, the interstitial environment can remodel in ways that decrease the elevated interstitial stress. Presently, relatively little is known about the glycosaminoglycans (GAGs) that become upregulated in the interstitium during lymphedema. We employed a mouse tail model of acute lymphedema that reproduces important features of the chronic human condition to establish a relationship between hyaluronan (HA) and sulfated GAG concentration with tissue swelling. We found that HA was upregulated by tissue injury at day 5 and became upregulated again by skin swelling (HA content increasing by 27% relative to controls at days 15 and 20). Surprisingly, the second phase of HA expression was associated with the declining phase of the tail skin swelling (tail diameter significantly decreasing by 17% from day 10 peak to day 20), demonstrating that HA is upregulated by tissue swelling and may help to counteract the edema in the mouse tail. This finding was confirmed by intradermal injection of an HA degrading enzyme (hyaluronidase) to the swollen tail, which was found to worsen the tail swelling. Sulfated GAGs, including chondroitin sulfate (CS), were not regulated by tissue swelling. The results demonstrate that HA, but not sulfated GAGs, is upregulated in the interstitium by acute tissue swelling. We speculate that HA expression during lymphedema may be part of a natural adaptive mechanism of the interstitial environment to reduce capillary filtration and increase interstitial fluid outflow following lymphatic obstruction and fluid accumulation.
Proteoglycans and hyaluronan play critical roles in heart development. In this study, human embryonic stem cells (hESC) were used as a model to quantify the synthesis of proteoglycans and hyaluronan in hESC in the early stages of differentiation, and after directed differentiation into cardiomyocytes. We demonstrated that both hESC and cardiomyocyte cultures synthesize an extracellular matrix (ECM) enriched in proteoglycans and hyaluronan. During cardiomyocyte differentiation, total proteoglycan and hyaluronan decreased and the proportion of proteoglycans bearing heparan sulfate chains was reduced. Versican, a chondroitin sulfate proteoglycan, accumulated in hESC and cardiomyocyte cultures. Furthermore, versican synthesized by hESC contained more N- and O-linked oligosaccharide than versican from cardiomyocytes. Transcripts for the versican variants, V0, V1, V2 and V3, increased in cardiomyocytes compared to hESC, with V1 most abundant. Hyaluronan in hESC had lower molecular weight than hyaluronan from cardiomyocyte cultures. These changes were accompanied by an increase in HAS-1 and HAS-2 mRNA in cardiomyocyte cultures, with HAS-2 most abundant. Interestingly, HAS-3 was absent from the cardiomyocyte cultures, but expressed by hESC. These results indicate that human cardiomyocyte differentiation is accompanied by specific changes in the expression and accumulation of ECM components and suggest a role for versican and hyaluronan in this process.
versican; hyaluronan; cardiomyocyte; differentiation; stem cells; glycosylation
Cardiac allograft vasculopathy (CAV) remains the main cause of long-term transplant rejection. It is characterized by hyperproliferation of vascular smooth muscle cells (VSMCs). Canonical β-catenin signaling is a critical regulator of VSMC proliferation in development; however, the role of this pathway and its regulation in CAV progression are obscure. We investigated the activity of β-catenin signaling and the role for a putative activating ligand, transglutaminase 2 (TG2), in chronic cardiac rejection.
Hearts from Bm12 mice were transplanted into C57BL/6 mice (Class II mismatch), and allografts were harvested 8 weeks after transplantation. Accumulation and sub-cellular distribution of β-catenin protein and expression of several components of β-catenin signaling were analyzed as hallmarks of pathway activation. In vitro, PDGF treatment was used to mimic the inflammatory milieu in VSMC and organotypic heart slice cultures.
Activation of β-catenin in allografts compared to isografts or naïve hearts was evidenced by the augmented expression of β-catenin target genes, as well as the accumulation and nuclear localization of the β-catenin protein in VSMCs of the occluded allograft vessels. Expression of TG2, an activator of β-catenin signaling in VSMCs, was dramatically increased in allografts. Further, our ex vivo data demonstrate that TG2 is required for VSMC proliferation and for β-catenin activation by PDGF in cardiac tissue.
β-catenin signaling is activated in occluded vessels in murine cardiac allografts. TG2 is implicated as an endogenous activator of this signaling pathway and may therefore have a role in the pathogenesis of CAV during chronic allograft rejection.
Heparan sulfate proteoglycans (HSPG) play a critical role in the formation of distinct fibroblast growth factor (FGF)-HS complexes, augmenting high-affinity binding and receptor activation. Perlecan, a secreted HSPG abundant in proliferating cells, is capable of inducing FGF-receptor interactions in vitro and angiogenesis in vivo. Stable and specific reduction of perlecan levels in mouse NIH 3T3 fibroblasts and human metastatic melanoma cells has been achieved by expression of antisense cDNA corresponding to the N-terminal and HS attachment domains of perlecan. Long-term perlecan downregulation is evidenced by reduced levels of perlecan mRNA and core protein as indicated by Northern blot analysis, immunoblots, and immunohistochemistry, using DNA probes and antibodies specific to mouse or human perlecan. The response of antisense perlecan-expressing cells to increasing concentrations of basic FGF (bFGF) is dramatically reduced in comparison to that in wild-type or vector-transfected cells, as measured by thymidine incorporation and rate of proliferation. Furthermore, receptor binding and affinity labeling of antisense perlecan-transfected cells with 125I-bFGF is markedly inhibited, indicating that eliminating perlecan expression results in reduced high-affinity bFGF binding. Both the binding and mitogenic response of antisense-perlecan-expressing clones to bFGF can be rescued by exogenous heparin or perlecan. These results support the notion that perlecan is a major accessory receptor for bFGF in mouse fibroblasts and human melanomas and point to the possible use of perlecan antisense constructs as specific modulators of bFGF-mediated responses.
Heparanase is an endo-β-glucuronidase that cleaves heparan sulfate side chains, leading to structural modifications that loosen the extracellular matrix barrier and associated with tumor metastasis, inflammation and angiogenesis. In addition, the highly sulfated heparan sulfate proteoglycans are important constituents of the glomerular basement membrane and its permselective properties. Recent studies suggest a role for heparanase in several experimental and human glomerular diseases associated with proteinuria such as diabetes, minimal change disease, and membranous nephropathy. Here, we quantified blood and urine heparanase levels in renal transplant recipients and patients with chronic kidney disease (CKD), and assessed whether alterations in heparanase levels correlate with proteinuria and renal function. We report that in transplanted patients, urinary heparanase was markedly elevated, inversely associated with estimated glomerular filtration rate (eGFR), suggesting a relationship between heparanase and graft function. In CKD patients, urinary heparanase was markedly elevated and associated with proteinuria, but not with eGFR. In addition, urinary heparanase correlated significantly with plasma heparanase in transplanted patients. Such a systemic spread of heparanase may lead to damage of cells and tissues alongside the kidney.The newly described association between heparanase, proteinuria and decreased renal function is expected to pave the way for new therapeutic options aimed at attenuating chronic renal allograft nephropathy, leading to improved graft survival and patient outcome.