Enzyme replacement therapy is currently available for three of the mucopolysaccharidoses (MPSs) but has limited effects on the skeletal lesions. We investigated the involvement of the Toll-like receptor 4 (TLR4) signaling pathway in the pathogenesis of MPS bone and joint disease, and the use of the anti-TNF-α drug, Remicade (Centocor, Inc.), for treatment. TLR4 KO (TLR4 (lps−/−) ) mice were interbred with MPS VII mice to produce double-KO (DKO) animals. The DKO mice had longer and thinner faces and longer femora as revealed by micro-computed tomography analysis compared with MPS VII mice. Histological analyses also revealed more organized and thinner growth plates. The serum levels of TNF-α were normalized in the DKO animals, and the levels of phosphorylated STAT1 and STAT3 in articular chondrocytes were corrected. These findings led us to evaluate the effects of Remicade in MPS VI rats. When initiated at 1 month of age, i.v. treatment prevented the elevation of TNF-α, receptor activator of NF-κB, and other inflammatory molecules not only in the blood but in articular chondrocytes and fibroblast-like synoviocytes (FLSs). Treatment of 6-monthold animals also reduced the levels of these molecules to normal. The number of apoptotic articular chondrocytes in MPS VI rats was similarly reduced, with less infiltration of synovial tissue into the underlying bone. These studies revealed the important role of TLR4 signaling in MPS bone and joint disease and suggest that targeting TNF-α may have positive therapeutic effects.bone and joint disease | inflammation | glycosaminoglycans | growth plate
BackgroundPentosan polysulfate (PPS) is an FDA-approved, oral medication with anti-inflammatory and pro-chondrogenic properties. We have previously shown that animal models of the mucopolysaccharidoses (MPS) exhibit significant inflammatory disease, contributing to cartilage degeneration. Enzyme replacement therapy (ERT) only partly reduced inflammation, and anti-TNF-alpha antibody therapy significantly enhanced clinical and pathological outcomes. Here we describe the use of PPS for the treatment of MPS type VI rats.Methodology/Principal FindingsTreatment began during prenatal development and at 1 and 6 months of age. All animals were treated until they were 9 months old. Significant reductions in the serum and tissue levels of several inflammatory markers (e.g., TNF-alpha, MIP-1alpha and RANTES/CCL5) were observed, as was reduced expression of inflammatory markers in cultured articular chondrocytes. ADAMTS-5/aggrecanase-2 levels also were reduced in chondrocytes, consistent with an elevation of serum tissue inhibitor of metalloproteinase 1. Marked improvements in motility and grooming behavior occurred, along with a reduction in eye and nasal secretions and a lessening of the tracheal deformities. MicroCT and radiographic analyses further revealed that the treated MPS skulls were longer and thinner, and that the teeth malocclusions, misalignments and mineral densities were improved. MicroCT analysis of the femurs and vertebrae revealed improvements in trabecular bone mineral densities, number and spacing in a subset of treated MPS animals. Biomechanical assessments of PPS-treated spines showed partially restored torsional behaviors, suggesting increased spinal stability. No improvements were observed in cortical bone or femur length. The positive changes in the PPS-treated MPS VI rats occurred despite glycosaminoglycan accumulation in their tissues.ConclusionsBased on these findings we conclude that PPS could be a simple and effective therapy for MPS that might provide significant clinical benefits alone and in combination with other therapies.
BackgroundAlthough enzyme replacement therapy (ERT) is available for several lysosomal storage disorders, the benefit of this treatment to the skeletal system is very limited. Our previous work has shown the importance of the Toll-like receptor 4/TNF-alpha inflammatory pathway in the skeletal pathology of the mucopolysaccharidoses (MPS), and we therefore undertook a study to examine the additive benefit of combining anti-TNF-alpha therapy with ERT in a rat model of MPS type VI.Methodology/Principal FindingsMPS VI rats were treated for 8 months with Naglazyme® (recombinant human N-acetyl-galactosamine-4-sulfatase), or by a combined protocol using Naglazyme® and the rat-specific anti-TNF-alpha drug, CNTO1081. Both protocols led to markedly reduced serum levels of TNF-alpha and RANKL, although only the combined treatment reduced TNF-alpha in the articular cartilage. Analysis of cultured articular chondrocytes showed that the combination therapy also restored collagen IIA1 expression, and reduced expression of the apoptotic marker, PARP. Motor activity and mobility were improved by ERT, and these were significantly enhanced by combination treatment. Tracheal deformities in the MPS VI animals were only improved by combination therapy, and there was a modest improvement in bone length. Ceramide levels in the trachea also were markedly reduced. MicroCT analysis did not demonstrate any significant positive effects on bone microarchitecture from either treatment, nor was there histological improvement in the bone growth plates.Conclusions/SignificanceThe results demonstrate that combining ERT with anti-TNF- alpha therapy improved the treatment outcome and led to significant clinical benefit. They also further validate the usefulness of TNF-alpha, RANKL and other inflammatory molecules as biomarkers for the MPS disorders. Further evaluation of this combination approach in other MPS animal models and patients is warranted.
BackgroundWe previously demonstrated the benefits of daily, oral pentosan polysulfate (PPS) treatment in a rat model of mucopolysaccharidosis (MPS) type VI. Herein we compare these effects to once weekly, subcutaneous (sc) injection. The bioavailability of injected PPS is greater than oral, suggesting better delivery to difficult tissues such as bone and cartilage. Injected PPS also effectively treats osteoarthritis in animals, and has shown success in osteoarthritis patients.Methodology/Principal FindingsOne-month-old MPS VI rats were given once weekly sc injections of PPS (1, 2 and 4 mg/kg, human equivalent dose (HED)), or daily oral PPS (4 mg/kg HED) for 6 months. Serum inflammatory markers and total glycosaminoglycans (GAGs) were measured, as were several histological, morphological and functional endpoints. Overall, weekly sc PPS injections led to similar or greater therapeutic effects as daily oral administration. Common findings between the two treatment approaches included reduced serum inflammatory markers, improved dentition and skull lengths, reduced tracheal deformities, and improved mobility. Enhanced effects of sc treatment included GAG reduction in urine and tissues, greater endurance on a rotarod, and better improvements in articular cartilage and bone in some dose groups. Optimal therapeutic effects were observed at 2 mg/kg, sc. No drug-related increases in liver enzymes, coagulation factor abnormalities or other adverse effects were identified following 6 months of sc PPS administration.ConclusionsOnce weekly sc administration of PPS in MPS VI rats led to equal or better therapeutic effects than daily oral administration, including a surprising reduction in urine and tissue GAGs. No adverse effects from sc PPS administration were observed over the 6-month study period.
Rotavirus is a nonenveloped, double-stranded RNA (dsRNA) virus responsible for acute gastroenteritis in the young of several animal species, including humans (1). The virus infects mature enterocytes present on intestinal villi. Transmission occurs via the fecal-oral route, although recent studies have confirmed extraintestinal spread and viremia in infected patients (2). Within the infected cell, six structural proteins (VP1 to VP4, VP6, and VP7) assemble into three concentric capsid layers that encase the segmented dsRNA genome (3, 4). Five nonstructural proteins (NSP1 to NSP5) are also synthesized in infected cells, and these play various roles in the replication of the viral genome, translation of viral mRNA, and virion morphogenesis (5).NSP4 is a transmembrane glycoprotein with an essential role in the assembly of intermediate double-layered particles and their maturation to infectious virions within the infected cell. NSP4 is also actively secreted from virus-infected polarized epithelial cells in its full-length form after specific posttranslational modification (6). The range of cellular and physiological effects attributed to exogenous NSP4 includes the ability to act as a virus-encoded enterotoxin capable of inducing dose-and age-dependent diarrhea in mice and rats (7), potentiation of Cl Ϫ and water secretion from noninfected epithelia (8), disruption of transepithelial resistance (9), and direct inhibition of the Na ϩ -D-glucose symporter transporter (10). Recombinant forms of NSP4 representing either the full-length protein or regions of the cytoplasmic domain have been demonstrated to cause the phospholipase C (PLC)-dependent elevation of intracellular Ca 2ϩ ions (11) and secretion of 5-hydroxytryptamine (5-HT) from enteroendocrine cells (12).Collectively, these studies indicate that NSP4 secreted from rotavirus-infected cells can interact with a range of cell types in vivo, initiate signaling pathways that affect the local physiology of the small intestine, and contribute to the clinical symptoms of rotavirus infection. Nevertheless, there remains a paucity of experimental data indicating how these apparently pleiotropic effects are regulated. For example, the nature and identity of plasma membrane receptors that activate intracellular signaling pathways in response to exogenous NSP4 are not well defined. Seo et al.reported that recombinant NSP4 can bind to the metal ion-dependent adhesion site (MIDAS) motif present on integrins ␣11 and ␣21 and activate intracellular signaling pathways that regulate cell spreading (13). Mutations in NSP4 that reduce integrin binding also correlated with an inability to cause diarrhea in mice. However, given the wide range of effects reported for NSP4, it is feasible that non-integrin receptors exist.The majority of studies into the cellular effects of NSP4 have focused on primary enterocytes and cell lines of intestinal epithelial origin. We observed recently that NSP4, purified from the medium of rotavirus-infected cells, bound to a wide range of cells of disti...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.