Makarand V Risbud

Thomas Jefferson University, Filadelfia, Pennsylvania, United States

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Publications (116)455.71 Total impact

  • Irving M Shapiro, William J Landis, Makarand V Risbud
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    ABSTRACT: Numerous studies have documented that matrix vesicles are unique extracellular membrane-bound microparticles that serve as initial sites for mineral formation in the growth plate and most other vertebrate mineralizing tissues. Microparticle generation is not confined to hard tissues, as cells in soft tissues generate similar structures; numerous studies have shown that a common type of extracellular particle, termed an exosome, a product of the endosomal pathway, shares many characteristics of matrix vesicles. Indeed, analyses of size, morphology and lipid and protein content indicate that matrix vesicles and exosomes are homologous structures. Such a possibility impacts our understanding of the biogenesis, processing and function of matrix vesicles (exosomes) in vertebrate hard tissues and explains in part how cells control the earliest stages of mineral deposition. Moreover, since exosomes influence a spectrum of functions, including cell-cell communication, it is suggested that this type of microparticle may provide a mechanism for the transfer of signaling molecules between cells within the growth plate and thereby regulate endochondral bone development and formation. Copyright © 2015. Published by Elsevier Inc.
    Bone 05/2015; DOI:10.1016/j.bone.2015.05.013 · 4.46 Impact Factor
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    ABSTRACT: Laboratory Study. To evaluate whether blockade of the Substance P (SP) receptor neurokinin receptor-1 (NK1R) attenuates its pro-inflammatory effect on human intervertebral disc cells (IVD), and to evaluate the signaling pathways associated with SP. SP and its receptors are expressed in human IVD cells, and cause upregulation of inflammatory mediators, however the effects of blocking these receptors has not been studied in human IVD cells. Human annulus fibrosus (AF) and nucleus pulposus (NP) cells were expanded in monolayer, and then suspended in alginate beads. The alginate beads were treated with culture medium first containing a high affinity NK1R antagonist (L-760735) at different concentrations, and then with medium containing both NK1R antagonist and SP at two concentrations. RNA was isolated and transcribed into cDNA. Quantitative RT-PCR was performed to evaluate expression of interleukin (IL)-1β, IL-6 and IL-8. Western blot analysis was performed to examine levels of the phosphorylated p38 mitogen-activated protein kinase (MAPK), extracellular signal regulated kinase 1/2 (ERK1/2) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB p65). The cells were pretreated with specific inhibitors of p38 (SB203580), ERK1/2 (PD98059) and p65 (SM7368) and then stimulated with SP. We detected expression of NK1R, neurokinin receptor 2 (NK2R) and neurokinin receptor 3(NK3R) in AF and NP cells. Treatment of disc cells with the NK1R antagonist was able to suppress expression of IL-1β, IL-6 and IL-8 in a dose-dependent manner. SP stimulation increased phosphorylation of p38-MAPK and ERK1/2, but not of NFκB p65. This indicates that p38-MAPK and ERK1/2 control SP-induced cytokine expression independently from NF-kB p65. Inhibition of p38 and ERK1/2 activation reduced SP-induced IL-6 production in human disc cells. NK1R is responsible for the pro-inflammatory effect of SP on IVD cells and this effect can be blocked by preventing binding of SP to NK1R. This study shows for the first time that SP mediates signaling in disc cells through NK1R and that SP activates the proinflammatory p38-MAPK and ERK1/2 pathways.
    Spine 04/2015; DOI:10.1097/BRS.0000000000000954 · 2.45 Impact Factor
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    ABSTRACT: Objectives of this study were to investigate whether AQP1 and AQP5 expression is altered during intervertebral disc degeneration and if hypoxia and HIF-1 regulate their expression in NP cells. AQP expression was measured in human tissues from different degenerative grades; regulation by hypoxia and HIF-1 was studied using promoter analysis and gain- and loss-of-function experiments. We show that both AQPs are expressed in the disc and that mRNA and protein levels decline with human disease severity. Bioinformatic analyses of AQP promoters showed multiple evolutionarily conserved HREs. Surprisingly, hypoxia failed to induce promoter activity or expression of either AQP. While genomic chromatin immunoprecipitation showed limited binding of HIF-1α to conserved HREs, their mutation did not suppress promoter activities. Stable HIF-1α suppression significantly decreased mRNA and protein levels of both AQPs, but HIF-1α failed to induce AQP levels following accumulation. Together, our results demonstrate that AQP1 and AQP5 expression is sensitive to human disc degeneration and that HIF-1α uniquely maintains basal expression of both AQPs in NP cells, independent of oxemic tension and HIF-1 binding to promoter HREs. Diminished HIF-1 activity during degeneration may suppress AQP levels in NP cells, compromising their ability to respond to extracellular osmolarity changes.
    Oncotarget 03/2015; · 6.63 Impact Factor
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    ABSTRACT: Prolyl-4-hydroxylase (PHD) proteins are key in sensing tissue hypoxia. In nucleus pulposus (NP) cells, our previous work has demonstrated that PHD isoforms have a differential contribution in controlling HIF-α degradation and activity. Recently we have shown that a regulatory relationship exists between PHD3 and inflammatory cytokines in NP cells. With respect to PHD2, the most abundant PHD isoform in NP cells, very little is known concerning its function and regulation under inflammatory conditions that characterize intervertebral disc degeneration. Here, we show that PHD2 is a potent regulator of the catabolic activities of TNF-α; silencing of PHD2 significantly decreased TNF-α-induced expression of catabolic markers including SDC4, MMP-3 and -13 and ADAMTS5 as well as several inflammatory cytokines and chemokines, while partially restoring aggrecan and collagen II expression. Use of NF-κB reporters with ShPHD2, SiHIF-1α, as well as p65-/-, PHD2-/- and PHD3-/- cells show that PHD2 serves as a co-activator of NF-κB/p65 signaling in HIF-1 independent fashion. Immunoprecipitation of endogenous and exogenously expressed tagged proteins as well as fluorescence microscopy indicates that following TNF-α treatment, PHD2 interacts with, and co-localizes with, p65. Conversely, loss-of-function experiments using lentivirally-delivered Sh-p65, Sh-IKKβ and NF-κB inhibitor confirmed that cytokine-dependent PHD2 expression in NP cells requires NF-κB signaling. These findings clearly demonstrate that PHD2 forms a regulatory circuit with TNF-α via NF-κB and thereby plays an important role in enhancing activity of this cytokine. We propose that during disc degeneration PHD2 may offer a therapeutic target to mitigate the deleterious actions of TNF-α, a key pro-inflammatory cytokine. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 01/2015; 290(11). DOI:10.1074/jbc.M114.611483 · 4.60 Impact Factor
  • Hyowon Choi, Zariel I Johnson, Makarand V Risbud
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    ABSTRACT: Intervertebral disc (IVD) degeneration and associated low back pain (LBP) remains a major burden to our society without a significant improvement in treatment strategies or patient's quality of life. While the recent cell-transplantation studies for treatment of degenerative disc disease showed promising results, to better gauge the success and functional outcomes of these therapies, it is crucial to understand if transplanted cells give rise to healthy nucleus pulposus (NP) tissue. NP cell phenotype is unique and is defined by expression of a characteristic set of markers that reflect their specialized physiology and function. This review summarizes phenotypic markers that mirror unique physiology and function of NP cells and their progenitors and should be considered to measure outcomes of cell-based therapies to treat disc degeneration.
    Current Stem Cell Research & Therapy 01/2015; · 2.86 Impact Factor
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    ABSTRACT: The objective of this study was to investigate whether expression of xylosyltransferase-1 (XT-1), a key enzyme in glycosaminoglycan biosynthesis, is responsive to disk degeneration and to inhibition by the inflammatory cytokines tumor necrosis factor α and IL-1β in nucleus pulposus (NP) cells. Analysis of human NP tissues showed that XT-1 expression is unaffected by degeneration severity; XT-1 and c-Jun, c-Fos, and Sp1 mRNA were positively correlated. Cytokines failed to inhibit XT-1 promoter activity and expression. However, cytokines decreased activity of XT-1 promoters containing deletion and mutation of the -730/-723 bp AP-1 motif, prompting us to investigate the role of AP-1 and Sp1/Sp3 in the regulation of XT-1 in healthy NP cells. Overexpression and suppression of AP-1 modulated XT-1 promoter activity. Likewise, treatment with the Sp1 inhibitors WP631 and mithramycin A or cotransfection with the plasmid DN-Sp1 decreased XT-1 promoter activity. Inhibitors of AP-1 and Sp1 and stable knockdown of Sp1 and Sp3 resulted in decreased XT-1 expression in NP cells. Genomic chromatin immunoprecipitation analysis showed AP-1 binding to motifs located at -730/-723 bp and -684/-677 bp and Sp1 binding to -227/-217 bp and -124/-114 bp in XT-1 promoter. These results suggest that XT-1 expression is refractory to the disease process and to inhibition by inflammatory cytokines and that signaling through AP-1, Sp1, and Sp3 is important in the maintenance of XT-1 levels in NP cells. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
    American Journal Of Pathology 12/2014; 185(2). DOI:10.1016/j.ajpath.2014.09.021 · 4.60 Impact Factor
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    Zariel I. Johnson, Irving M. Shapiro, Makarand V. Risbud
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    ABSTRACT: Degeneration of the intervertebral disc is characterized by changes in proteoglycan status, loss of bound water molecules, decreased tissue osmotic pressure and a resulting mechanical failure of the disc. A similar spectrum of changes is evident in osteoarthritic articular cartilage. When healthy, resident cells in these skeletal tissues respond to applied mechanical loads by regulating their own osmotic state and the hydration of the extracellular matrix. The transcription factor Tonicity-Responsive Enhancer Binding Protein (TonEBP or NFAT5) is known to mediate the osmoadaptive response in these and other tissues. While the molecular basis of how osmotic loading controls matrix homeostasis is not completely understood, TonEBP regulates the expression of aggrecan and β1,3-glucoronosyltransferase in nucleus pulposus cells, in addition to targets that allow for survival under hypertonic stress. Moreover, in chondrocytes, TonEBP controls expression of several collagen subtypes and Sox9, a master regulator of aggrecan and collagen II expression. Thus, TonEBP-mediated regulation of the matrix composition allows disc cells and chondrocytes to modify the extracellular osmotic state itself. On the other hand, TonEBP in immune cells induces expression of TNF-α, ΙL-6 and MCP-1, pro-inflammatory molecules closely linked to matrix catabolism and pathogenesis of both disc degeneration and osteoarthritis, warranting investigations of this aspect of TonEBP function in skeletal cells. In summary, the TonEBP system, through its effects on extracellular matrix and osmoregulatory genes can be viewed primarily as a protective or homeostatic response to physiological loading.
    Matrix Biology 11/2014; 40. DOI:10.1016/j.matbio.2014.08.014 · 3.65 Impact Factor
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    ABSTRACT: Low back pain is a major physical and socioeconomic problem. Degeneration of the intervertebral disc and especially that of nucleus pulposus (NP) has been linked to low back pain. In spite of much research focusing on the NP, consensus among the research community is lacking in defining the NP cell phenotype. A consensus agreement will allow easier distinguishing of NP cells from annulus fibrosus (AF) cells and endplate chondrocytes, a better gauge of therapeutic success, and a better guidance of tissue-engineering-based regenerative strategies that attempt to replace lost NP tissue. Most importantly, a clear definition will further the understanding of physiology and function of NP cells, ultimately driving development of novel cell-based therapeutic modalities. The Spine Research Interest Group at the 2014 Annual ORS Meeting in New Orleans convened with the task of compiling a working definition of the NP cell phenotype with hope that a consensus statement will propel disc research forward into the future. Based on evaluation of recent studies describing characteristic NP markers and their physiologic relevance, we make the recommendation of the following healthy NP phenotypic markers: stabilized expression of HIF-1α, GLUT-1, aggrecan/collagen II ratio > 20, Shh, Brachyury, KRT18/19, CA12, and CD24. This article is protected by copyright. All rights reserved
    Journal of Orthopaedic Research 11/2014; 33(3). DOI:10.1002/jor.22789 · 2.97 Impact Factor
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    ABSTRACT: Study Design. Laboratory study. Objective. To evaluate the differential gene expression of cytokines and growth factors in anterior versus posterior annulus fibrosus (AF) intervertebral disc (IVD) specimens. Summary of Background Data. Histological analysis has demonstrated regional differences in vascular and neural ingrowth in the IVD, and similar differences may exist for cytokine and growth factor expression in patients with degenerative disc disease (DDD). Regional expression of these cytokines may also be related to the pain experienced in DDD. Methods. IVD tissue was obtained from patients undergoing anterior lumbar interbody fusion surgery for back pain with radiological evidence of disc degeneration. For a control group, the discs of patients undergoing anterior lumbar discectomy for degenerative scoliosis were obtained as well. The tissue was carefully removed and separated into anterior and posterior AF. After tissue processing, an antibody array was completed to determine expression levels of 42 cytokines and growth factors. Results. Nine discs from 7 patients with DDD and 5 discs from 2 patients with scoliosis were analyzed. In the DDD group, there were 10 cytokines and growth factors with significantly increased expression in the posterior AF versus the anterior AF ([interleukin] IL-4, IL-5, IL-6, M-CSF, MDC, tumor necrosis factor beta, EGF, IGF-1, angiogenin, leptin). In the scoliosis group, only angiogenin and PDGF-BB demonstrated increased expression in the posterior AF. No cytokines or growth factors had increased expression in the anterior AF compared with posterior AF. Conclusion. The posterior AF expresses increased levels of cytokines and growth factors compared with the anterior AF in patients with DDD. This differential expression may be important for targeting treatment of painful IVDs.
    Spine 11/2014; 39(23):1917-23. DOI:10.1097/BRS.0000000000000590 · 2.45 Impact Factor
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    ABSTRACT: The intervertebral disc (IVD) is one of the largest avascular organs in vertebrates. The nucleus pulposus (NP), a highly hydrated and proteoglycan-enriched tissue, forms the inner portion of the IVD. The NP is surrounded by a multi-lamellar fibrocartilaginous structure, the annulus fibrosus (AF). This structure is covered superior and inferior side by cartilaginous endplates (CEP). The NP is a unique tissue within the IVD as it results from the differentiation of notochordal cells, whereas, AF and CEP derive from the sclerotome. The hypoxia inducible factor-1α (HIF-1α) is expressed in NP cells but its function in NP development and homeostasis is largely unknown. We thus conditionally deleted HIF-1α in notochordal cells and investigated how loss of this transcription factor impacts NP formation and homeostasis at E15.5, birth, 1 and 4 months of age, respectively. Histological analysis, cell lineage studies, and TUNEL assay were performed. Morphologic changes of the mutant NP cells were identified as early as E15.5, followed, postnatally, by the progressive disappearance and replacement of the NP with a novel tissue that resembles fibrocartilage. Notably, lineage studies and TUNEL assay unequivocally proved that NP cells did not transdifferentiate into chondrocyte-like cells but they rather underwent massive cell death, and were completely replaced by a cell population belonging to a lineage distinct from the notochordal one. Finally, to evaluate the functional consequences of HIF-1α deletion in the NP, biomechanical testing of mutant IVD was performed. Loss of the NP in mutant mice significantly reduced the IVD biomechanical properties by decreasing its ability to absorb mechanical stress. These findings are similar to the changes usually observed during human IVD degeneration. Our study thus demonstrates that HIF-1α is essential for NP development and homeostasis, and it raises the intriguing possibility that this transcription factor could be involved in IVD degeneration in humans.
    PLoS ONE 10/2014; 9(10):e110768. DOI:10.1371/journal.pone.0110768 · 3.53 Impact Factor
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    ABSTRACT: Matrix metalloproteinase-3 (MMP-3) plays an important role in intervertebral disc degeneration, a ubiquitous condition closely linked to low back pain and disability. Elevated expression of syndecan 4, a cell surface heparan sulfate proteoglycan, actively controls disc matrix catabolism. However, the relationship between MMP-3 expression and syndecan 4 in the context of inflammatory disc disease has not been clearly defined. We investigated the mechanisms by which cytokines control MMP-3 expression in rat and human nucleus pulposus cells. Cytokine treatment increased MMP-3 expression and promoter activity. Stable silencing of syndecan 4 blocked cytokine-mediated MMP-3 expression; more important, syndecan 4 did not mediate its effects through NF-κB or mitogen-activated protein kinase (MAPK) pathways. However, treatment with MAPK and NF-κB inhibitors resulted in partial blocking of the inductive effect of cytokines on MMP-3 expression. Loss-of-function studies confirmed that NF-κB, p38α/β2/γ/δ, and extracellular signal-regulated kinase (ERK) 2, but not ERK1, contributed to cytokine-dependent induction of MMP3 promoter activity. Similarly, inhibitor treatments, lentiviral short hairpin-p65, and short hairpin-I κ B kinase β significantly decreased cytokine-dependent up-regulation in MMP-3 expression. Finally, we show that transforming growth factor-β can block the up-regulation of MMP-3 induced by tumor necrosis factor (TNF)-α by counteracting the NF-κB pathway and syndecan 4 expression. Taken together, our results suggest that cooperative signaling through syndecan 4 and the TNF receptor 1-MAPK-NF-κB axis is required for TNF-α-dependent expression of MMP-3 in nucleus pulposus cells. Controlling these pathways may slow the progression of intervertebral disc degeneration and matrix catabolism.
    American Journal Of Pathology 07/2014; DOI:10.1016/j.ajpath.2014.06.006 · 4.60 Impact Factor
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    ABSTRACT: The objective of this study was to determine the role of FIH-1 in regulating HIF-1 activity in the nucleus pulposus (NP) cells, and the control of this regulation by binding and sequestration of FIH-1 by Mint3. FIH-1 and Mint3 were both expressed in the NP, and were shown to strongly co-localize within the cell nucleus. While both mRNA and protein expression of FIH-1 decreased in hypoxia, only Mint3 protein levels were hypoxia sensitive. Overexpression of FIH-1 was able to reduce HIF-1 function as seen by changes in activities of HRE-luciferase reporter and HIF-1α-CTAD and HIF-2α-TAD. Moreover, co-transfection of either full-length Mint3 or the N-terminus of Mint3 abrogated FIH-1-dependent reduction in HIF-1 activity under both normoxia and hypoxia. Nuclear levels of FIH-1 and Mint3 decreased in hypoxia, and use of specific nuclear import and export inhibitors clearly showed that cellular compartmentalization of overexpressed FIH-1 was critical for its regulation of HIF-1 activity in NP cells. Interestingly, microarray results after stable silencing of FIH-1 showed no significant changes in transcripts of classical HIF-1 target genes. However, expression of several other transcripts, including those of Notch pathway changed in FIH-1 silenced cells. Moreover, co-transfection of Notch-ICD could restore suppression of HIF1-TAD activity by exogenous FIH-1. Taken together, these results suggest that possibly due to low endogenous levels and/or preferential association with substrates such as Notch, FIH-1 activity does not represent a major mechanism by which NP cells control HIF-1-dependent transcription, a testament to their adaptation to a unique hypoxic niche.
    Journal of Biological Chemistry 05/2014; 289(30). DOI:10.1074/jbc.M114.565101 · 4.60 Impact Factor
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    05/2014; 04(S 01). DOI:10.1055/s-0034-1376558
  • 05/2014; 04(S 01). DOI:10.1055/s-0034-1376626
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    ABSTRACT: Intervertebral disc degeneration is the leading cause of chronic back pain. Recent studies show that raised level of SDC4, a cell-surface heparan sulfate (HS) proteoglycan, plays a role in pathogenesis of disc degeneration. However, in nucleus pulposus (NP) cells of the healthy intervertebral disc, the mechanisms that control expression of SDC4 and its physiological function are unknown. Hypoxia induced SDC4 mRNA and protein expression by ∼2.4- and 4.4-fold (P<0.05), respectively, in NP cells. While the activity of the SDC4 promoter containing hypoxia response element (HRE) was induced 2-fold (P<0.05), the HRE mutation decreased the activity by 40% in hypoxia. Transfections with plasmids coding prolyl-4-hydroxylase domain protein 2 (PHD2) and ShPHD2 show that hypoxic expression of SDC4 mRNA and protein is regulated by PHD2 through controlling hypoxia-inducible factor 1α (HIF-1α) levels. Although overexpression of HIF-1α significantly increased SDC4 protein levels, stable suppression of HIF-1α and HIF-1β decreased SDC4 expression by 50% in human NP cells. Finally, suppression of SDC4 expression, as well as HS function, resulted in an ∼2-fold increase in sex-determining region Y (SRY)-box 9 (Sox9) mRNA, and protein (P<0.05) and simultaneous increase in Sox9 transcriptional activity and target gene expression. Taken together, our findings suggest that in healthy discs, SDC4, through its HS side chains, contributes to maintenance of the hypoxic tissue niche by controlling baseline expression of Sox9.-Fujita, N., Hirose, Y., Tran, C. M., Chiba, K., Miyamoto, T., Toyama, Y., Shapiro, I. M., Risbud, M. V. HIF-1-PHD2 axis controls expression of syndecan 4 in nucleus pulposus cells.
    The FASEB Journal 02/2014; 28(6). DOI:10.1096/fj.13-243741 · 5.48 Impact Factor
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    ABSTRACT: The objective of the study was to examine the regulation of CCN2 by inflammatory cytokines, IL-1β and TNF-α and to determine if CCN2 modulates IL-1β-dependent catabolic gene expression in nucleus pulposus (NP) cells. IL-1β and TNF-α suppress CCN2 mRNA and protein expression in an NF-κB dependent but MAPK independent manner. The conserved κB sites located at -93/-86 and -546/-537 bp in the CCN2 promoter mediated this suppression. On the other hand, treatment of NP cells with IL-1β in combination with CCN2 suppressed the inductive effect of IL-1β on catabolic genes, including MMP-3, ADAMTS-5, syndecan 4 (SDC4) and prolyl hydroxylase 3 (PHD3). Likewise, silencing of CCN2 in human NP cells resulted in elevated basal expression of several catabolic genes and inflammatory cytokines like IL-6, IL-4 and IL-12 as measured by gene expression and cytokine protein array respectively. Interestingly, the suppressive effect of CCN2 on IL-1β was independent of modulation of NF-κB signaling. Using disintegrins, echistatin (ECH) and VLO4, peptide inhibitors to αvβ3 and α5β1 integrins, we showed that CCN2 binding to both integrins was required for the inhibition of IL-1β-induced catabolic gene expression. Noteworthy, analysis of human tissues showed a trend of altered expression of these integrins during degeneration. Taken together, these results suggest that CCN2 and inflammatory cytokines form a functional negative feedback loop in NP cells that may be important in the pathogenesis of disc disease.
    Journal of Biological Chemistry 01/2014; 289(11). DOI:10.1074/jbc.M113.526111 · 4.60 Impact Factor
  • Makarand V Risbud, Irving M Shapiro
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    ABSTRACT: Degeneration of the intervertebral discs (IVDs) is a major contributor to back, neck and radicular pain. IVD degeneration is characterized by increases in levels of the proinflammatory cytokines TNF, IL-1α, IL-1β, IL-6 and IL-17 secreted by the IVD cells; these cytokines promote extracellular matrix degradation, chemokine production and changes in IVD cell phenotype. The resulting imbalance in catabolic and anabolic responses leads to the degeneration of IVD tissues, as well as disc herniation and radicular pain. The release of chemokines from degenerating discs promotes the infiltration and activation of immune cells, further amplifying the inflammatory cascade. Leukocyte migration into the IVD is accompanied by the appearance of microvasculature tissue and nerve fibres. Furthermore, neurogenic factors, generated by both disc and immune cells, induce expression of pain-associated cation channels in the dorsal root ganglion. Depolarization of these ion channels is likely to promote discogenic and radicular pain, and reinforce the cytokine-mediated degenerative cascade. Taken together, an enhanced understanding of the contribution of cytokines and immune cells to these catabolic, angiogenic and nociceptive processes could provide new targets for the treatment of symptomatic disc disease. In this Review, the role of key inflammatory cytokines during each of the individual phases of degenerative disc disease, as well as the outcomes of major clinical studies aimed at blocking cytokine function, are discussed.
    Nature Reviews Rheumatology 10/2013; DOI:10.1038/nrrheum.2013.160 · 10.25 Impact Factor
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    ABSTRACT: Despite many advances in our understanding of the molecular basis of disc degeneration, there remains a paucity of preclinical models which can be used to study the biochemical and molecular events that drive disc degeneration, and the effects of potential therapeutic interventions. The goal of this study is to characterize global gene expression changes in a disc organ culture system that mimics early nontraumatic disc degeneration. To mimic a degenerative insult, rat intervertebral discs were cultured in the presence of TNF-a, IL-1ß and serum-limiting conditions. Gene expression analysis was performed using a microarray to identify differential gene expression between experimental and control groups. Differential pattern of gene expression was confirmed using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) or Western blot. Treatment resulted in significant changes in expression of more than 1,000 genes affecting many aspects of cell function including cellular movement, the cell cycle, cellular development, and cell death and proliferation. Many of the most highly upregulated and downregulated genes have known functions in disc degeneration and extracellular matrix hemostasis. Construction of gene networks based on known cellular pathways and expression data from our analysis demonstrated that the network associated with cell death, cell cycle regulation and DNA replication and repair was most heavily affected in this model of disc degeneration. This rat organ culture model uses cytokine exposure to induce wide gene expression changes with the most affected genes having known reported functions in disc degeneration. We propose that this model is a valuable tool to study the etiology of disc degeneration and evaluate potential therapeutic treatments.
    Arthritis research & therapy 09/2013; 15(5):R121. DOI:10.1186/ar4301 · 4.12 Impact Factor
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    ABSTRACT: Study Design: Laboratory study.Objective: The aims of this study were 1) To confirm that Substance P (SP) is expressed by nucleus pulposus (NP) and annulus fibrosus (AF) cells; 2) To determine the effect of SP on expression of inflammatory mediators in human disc cells and the effect of inflammatory mediators on expression of SP; and 3) To characterize the relative expression of SP receptor isoforms in disc tissue and describe whether exposure to SP changes receptor expression.Summary of Background Data: Substance P, classically described as a neurotransmitter, acts as an inflammatory regulator in other tissue types but its role within the intervertebral disc has not been characterized.Methods: Human AF and NP cells from 7 individuals were expanded in monolayer and maintained in alginate bead culture. Cells were treated with SP or IL-1β/TNF-α. After treatment, the cells were recovered, RNA was isolated and transcribed into cDNA. Quantitative RT-PCR was performed to evaluate expression of inflammatory mediators, SP and its receptors.Results: Disc cells treated with SP demonstrated significant upregulation of IL-1β, IL-6 and IL-8 in NP and AF cells while significant upregulation of RANTES and TNF occurred only in the AF. SP was expressed by AF and NP cells at low levels; expression did not change significantly with SP treatment but was significantly upregulated after treatment with IL-1β/TNF-α. Both SP receptor isoforms were expressed by NP and AF cells.Conclusion: SP upregulates inflammatory mediators in disc cells. SP and SP receptors were expressed in both NP and AF and expression did not change after treatment with SP but increased after treatment with IL-1β/TNF-α. SP likely acts in an autocrine or paracrine manner in IVD cells and may be involved in "crosstalk" between disc cells and neurons, providing a potential mechanism for transmission of painful discogenic stimuli.
    Spine 07/2013; DOI:10.1097/BRS.0b013e3182a42bc2 · 2.45 Impact Factor
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    ABSTRACT: STUDY DESIGN.: Laboratory study. OBJECTIVE.: To evaluate expression of chemokine regulated and normal T cell expressed and secreted (RANTES)/C-C motif ligand 5 (CCL5) and interleukins in intervertebral discs (IVDs) specimens from patients with discogram-proven painful degeneration. SUMMARY OF BACKGROUND DATA.: Discogenic back pain results in tremendous costs related to treatment and lost productivity. The relationship between inflammation, degeneration (IVD), and cytokine upregulation is well established, but other mediators of the inflammatory cascade are not well characterized. METHODS.: Painful IVDs were taken from 18 patients undergoing surgery for discogenic pain with positive preoperative discogram. Painless control tissue was taken at autopsy from patients without back pain/spinal pathology or spinal levels with negative discograms resected for deformity.Quantitative real time polymerase chain reaction (qRT-PCR) was performed to evaluate RANTES, IL-1β, IL-6, and IL-8 expression in painful and control discs. RANTES and interleukin expression were analyzed on the basis of Pfirrmann grade.Disc cells were cultured in alginate beads using 2 groups: an untreated group and a group treated with 10 ng/mL IL-1β, 10 ng/mL TNF-α, and 1% fetal bovine serum to induce a degenerative phenotype. RESULTS.: Nine painless IVD specimens and 7 painful IVD specimens were collected. RANTES expression demonstrated a 3.60-fold increase in painful discs versus painless discs, a significant difference (P = 0.049). IL-1β expression demonstrated significantly higher expression in painful discs (P = 0.03). RANTES expression data demonstrated significant upregulation with increasing Pfirrmann grade (P = 0.045). RANTES expression correlated significantly with IL-1β expression (ρ = 0.67, P < 0.0001). RANTES expression increased more than 200-fold in the alginate culture model in cells treated with IL-1β/TNF-α, 1% fetal bovine serum (P < 0.001). CONCLUSION.: RANTES and IL-1β expression was significantly elevated in painful IVDs after careful selection of painless versus painful IVD tissue. RANTES expression was found to correlate significantly with expression of IL-1β. RANTES was upregulated by IL-1β/TNF-α/1% fetal bovine serum an in vitro treatment to induce a degenerative phenotype.
    Spine 05/2013; 38(11):873-80. DOI:10.1097/BRS.0b013e318285ae08 · 2.45 Impact Factor

Publication Stats

4k Citations
455.71 Total Impact Points

Institutions

  • 2002–2015
    • Thomas Jefferson University
      • Department of Orthopaedic Surgery
      Filadelfia, Pennsylvania, United States
    • Sree Chitra Tirunal Institute for Medical Sciences and Technology
      Tiruvananantapuram, Kerala, India
  • 2012
    • Thomas Jefferson University Hospitals
      Philadelphia, Pennsylvania, United States
  • 2010
    • Jefferson College
      Хиллсборо, Missouri, United States
  • 2007
    • The Children's Hospital of Philadelphia
      • Department of Pathology and Laboratory Medicine
      Filadelfia, Pennsylvania, United States
  • 2005
    • Drexel University
      Filadelfia, Pennsylvania, United States
  • 1999–2003
    • National Centre For Cell Science, Pune
      Poona, Mahārāshtra, India
  • 2000
    • Indian Institute of Technology Bombay
      Mumbai, Mahārāshtra, India