@article{KrupkovaZvickWuertzKozak2017,
  author    = {Krupkova, Olga and Zvick, Johannes and W{\"u}rtz-Kozak, Karin},
  title     = {The role of transient receptor potential channels in joint diseases},
  series = {European cells \& materials},
  volume    = {34},
  journal   = {European cells \& materials},
  publisher = {Univ. of Wales},
  address   = {Aberystwyth},
  issn      = {1473-2262},
  doi       = {10.22203/eCM.v034a12},
  pages     = {180 -- 201},
  year      = {2017},
  abstract  = {Transient receptor potential channels (TRP channels) are cation selective transmembrane receptors with diverse structures, activation mechanisms and physiological functions. TRP channels act as cellular sensors for a plethora of stimuli, including temperature, membrane voltage, oxidative stress, mechanical stimuli, pH and endogenous as well as exogenous ligands, thereby illustrating their versatility. As such, TRP channels regulate various functions in both excitable and non-excitable cells, mainly by mediating Ca2+ homeostasis. Dysregulation of TRP channels is implicated in many pathologies, including cardiovascular diseases, muscular dystrophies and hyperalgesia. However, the importance of TRP channel expression, physiological function and regulation in chondrocytes and intervertebral disc (IVD) cells is largely unexplored. Osteoarthritis (OA) and degenerative disc disease (DDD) are chronic age-related disorders that significantly affect the quality of life by causing pain, activity limitation and disability. Furthermore, currently available therapies cannot effectively slow-down or stop progression of these diseases. Both OA and DDD are characterised by reduced tissue cellularity, enhanced inflammatory responses and molecular, structural and mechanical alterations of the extracellular matrix, hence affecting load distribution and reducing joint flexibility. However, knowledge on how chondrocytes and IVD cells sense their microenvironment and respond to its changes is still limited. In this review, we introduced six families of mammalian TRP channels, their mechanisms of activation as well as activation-driven cellular consequences. We summarised the current knowledge on TRP channel expression and activity in chondrocytes and IVD cells and the significance of TRP channels as therapeutic targets for the treatment of OA and DDD.},
  language  = {en}
}
@article{KrupkovaSadowskaKamedaetal.2018,
  author    = {Krupkova, Olga and Sadowska, Aleksandra and Kameda, Takuya and Hitzl, Wolfgang and Hausmann, Oliver Nic and Klasen, J{\"u}rgen and Wuertz-Kozak, Karin},
  title     = {p38 MaPK Facilitates crosstalk Between endoplasmic reticulum stress and IL-6 release in the intervertebral Disc},
  series = {Frontiers in Immunology},
  volume    = {9},
  journal   = {Frontiers in Immunology},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {1664-3224},
  doi       = {10.3389/fimmu.2018.01706},
  pages     = {14},
  year      = {2018},
  abstract  = {Degenerative disc disease is associated with increased expression of pro-inflammatory cytokines in the intervertebral disc (IVD). However, it is not completely clear how inflammation arises in the IVD and which cellular compartments are involved in this process. Recently, the endoplasmic reticulum (ER) has emerged as a possible modulator of inflammation in age-related disorders. In addition, ER stress has been associated with the microenvironment of degenerated IVDs. Therefore, the aim of this study was to analyze the effects of ER stress on inflammatory responses in degenerated human IVDs and associated molecular mechanisms. Gene expression of ER stress marker GRP78 and pro-inflammatory cytokines IL-6, IL-8, IL-1 beta, and TNF-alpha was analyzed in human surgical IVD samples (n = 51, Pfirrmann grade 2-5). The expression of GRP78 positively correlated with the degeneration grade in lumbar IVDs and IL-6, but not with IL-1 beta and TNF-alpha. Another set of human surgical IVD samples (n = 25) was used to prepare primary cell cultures. ER stress inducer thapsigargin (Tg, 100 and 500 nM) activated gene and protein expression of IL-6 and induced phosphorylation of p38 MAPK. Both inhibition of p38 MAPK by SB203580 (10 mu M) and knockdown of ER stress effector CCAAT-enhancer-binding protein homologous protein (CHOP) reduced gene and protein expression of IL-6 in Tg-treated cells. Furthermore, the effects of an inflammatory microenvironment on ER stress were tested. TNF-alpha (5 and 10 ng/mL) did not activate ER stress, while IL-1 beta (5 and 10 ng/mL) activated gene and protein expression of GRP78, but did not influence [Ca2+](i) flux and expression of CHOP, indicating that pro-inflammatory cytokines alone may not induce ER stress in vivo. This study showed that IL-6 release in the IVD can be initiated following ER stress and that ER stress mediates IL-6 release through p38 MAPK and CHOP. Therapeutic targeting of ER stress response may reduce the consequences of the harsh microenvironment in degenerated IVD.},
  language  = {en}
}
@article{SadowskaKamedaKrupkovaetal.2018,
  author    = {Sadowska, Aleksandra and Kameda, Takuya and Krupkova, Olga and Wuertz-Kozak, Karin},
  title     = {Osmosensing, osmosignalling and inflammation},
  series = {European cells \& materials},
  volume    = {36},
  journal   = {European cells \& materials},
  publisher = {Ao research institute davos-Ari},
  address   = {Davos},
  issn      = {1473-2262},
  doi       = {10.22203/eCM.v036a17},
  pages     = {231 -- 250},
  year      = {2018},
  abstract  = {Intervertebral disc (IVD) cells are naturally exposed to high osmolarity and complex mechanical loading, which drive microenvironmental osmotic changes. Age- and degeneration-induced degradation of the IVD's extracellular matrix causes osmotic imbalance, which, together with an altered function of cellular receptors and signalling pathways, instigates local osmotic stress. Cellular responses to osmotic stress include osmoadaptation and activation of pro-inflammatory pathways. This review summarises the current knowledge on how IVD cells sense local osmotic changes and translate these signals into physiological or pathophysiological responses, with a focus on inflammation. Furthermore, it discusses the expression and function of putative membrane osmosensors (e.g. solute carrier transporters, transient receptor potential channels, aquaporins and acid-sensing ion channels) and osmosignalling mediators [e.g. tonicity response-element-binding protein/nuclear factor of activated T-cells 5 (TonEBP/NFAT5), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)] in healthy and degenerated IVDs. Finally, an overview of the potential therapeutic targets for modifying osmosensing and osmosignalling in degenerated IVDs is provided.},
  language  = {en}
}
@article{KamedaZvickVuketal.2019,
  author    = {Kameda, Takuya and Zvick, Joel and Vuk, Miriam and Sadowska, Aleksandra and Tam, Wai Kit and Leung, Victor Y. and B{\"o}lcskei, Kata and Helyes, Zsuzsanna and Applegate, Lee Ann and Hausmann, Oliver N. and Klasen, Juergen and Krupkova, Olga and W{\"u}rtz-Kozak, Karin},
  title     = {Expression and Activity of TRPA1 and TRPV1 in the Intervertebral Disc},
  series = {International journal of molecular sciences},
  volume    = {20},
  journal   = {International journal of molecular sciences},
  number    = {7},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1422-0067},
  doi       = {10.3390/ijms20071767},
  pages     = {23},
  year      = {2019},
  abstract  = {Transient receptor potential (TRP) channels have emerged as potential sensors and transducers of inflammatory pain. The aims of this study were to investigate (1) the expression of TRP channels in intervertebral disc (IVD) cells in normal and inflammatory conditions and (2) the function of Transient receptor potential ankyrin 1 (TRPA1) and Transient receptor potential vanilloid 1 (TRPV1) in IVD inflammation and matrix homeostasis. RT-qPCR was used to analyze human fetal, healthy, and degenerated IVD tissues for the gene expression of TRPA1 and TRPV1. The primary IVD cell cultures were stimulated with either interleukin-1 beta (IL-1) or tumor necrosis factor alpha (TNF-) alone or in combination with TRPA1/V1 agonist allyl isothiocyanate (AITC, 3 and 10 mu M), followed by analysis of calcium flux and the expression of inflammation mediators (RT-qPCR/ELISA) and matrix constituents (RT-qPCR). The matrix structure and composition in caudal motion segments from TRPA1 and TRPV1 wild-type (WT) and knock-out (KO) mice was visualized by FAST staining. Gene expression of other TRP channels (A1, C1, C3, C6, V1, V2, V4, V6, M2, M7, M8) was also tested in cytokine-treated cells. TRPA1 was expressed in fetal IVD cells, 20\% of degenerated IVDs, but not in healthy mature IVDs. TRPA1 expression was not detectable in untreated cells and it increased upon cytokine treatment, while TRPV1 was expressed and concomitantly reduced. In inflamed IVD cells, 10 mu M AITC activated calcium flux, induced gene expression of IL-8, and reduced disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) and collagen 1A1, possibly via upregulated TRPA1. TRPA1 KO in mice was associated with signs of degeneration in the nucleus pulposus and the vertebral growth plate, whereas TRPV1 KO did not show profound changes. Cytokine treatment also affected the gene expression of TRPV2 (increase), TRPV4 (increase), and TRPC6 (decrease). TRPA1 might be expressed in developing IVD, downregulated during its maturation, and upregulated again in degenerative disc disease, participating in matrix homeostasis. However, follow-up studies with larger sample sizes are needed to fully elucidate the role of TRPA1 and other TRP channels in degenerative disc disease.},
  language  = {en}
}
@article{LoepfeDussZafeiropoulouetal.2019,
  author    = {L{\"o}pfe, Moira and Duss, Anja and Zafeiropoulou, Katerina-Alexandra and Bjoergvinsdottir, Oddny and Eglin, David and Fortunato, Giuseppino and Klasen, J{\"u}rgen and Ferguson, Stephen J. and W{\"u}rtz-Kozak, Karin and Krupkova, Olga},
  title     = {Electrospray-Based Microencapsulation of Epigallocatechin 3-Gallate for Local Delivery into the Intervertebral Disc},
  series = {Pharmaceutics},
  volume    = {11},
  journal   = {Pharmaceutics},
  number    = {9},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1999-4923},
  doi       = {10.3390/pharmaceutics11090435},
  pages     = {15},
  year      = {2019},
  abstract  = {Locally delivered anti-inflammatory compounds can restore the homeostasis of the degenerated intervertebral disc (IVD). With beneficial effects on IVD cells, epigallocatechin 3-gallate (EGCG) is a promising therapeutic candidate. However, EGCG is prone to rapid degradation and/or depletion. Therefore, the purpose of this study was to develop a method for controlled EGCG delivery in the degenerated IVD. Primary IVD cells were isolated from human donors undergoing IVD surgeries. EGCG was encapsulated into microparticles by electrospraying of glutaraldehyde-crosslinked gelatin. The resulting particles were characterized in terms of cytocompatibility and anti-inflammatory activity, and combined with a thermoresponsive carrier to produce an injectable EGCG delivery system. Subsequently, electrospraying was scaled up using the industrial NANOSPIDER (TM) technology. The produced EGCG microparticles reduced the expression of inflammatory (IL-6, IL-8, COX-2) and catabolic (MMP1, MMP3, MMP13) mediators in pro-inflammatory 3D cell cultures. Combining the EGCG microparticles with the carrier showed a trend towards modulating EGCG activity/release. Electrospray upscaling was achieved, leading to particles with homogenous spherical morphologies. In conclusion, electrospray-based encapsulation of EGCG resulted in cytocompatible microparticles that preserved the activity of EGCG and showed the potential to control EGCG release, thus favoring IVD health by downregulating local inflammation. Future studies will focus on further exploring the biological activity of the developed delivery system for potential clinical use.},
  language  = {en}
}