@phdthesis{Reinhold2016,
  author    = {Reinhold, Ann-Kristin},
  title     = {New players in neuropathic pain? microRNA expression in dorsal root ganglia and differential transcriptional profiling in primary sensory neurons},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140314},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2016},
  abstract  = {Neuropathic pain, caused by neuronal damage, is a severely impairing mostly chronic condition. Its underlying molecular mechanisms have not yet been thoroughly understood in their variety. In this doctoral thesis, I investigated the role of microRNAs (miRNAs) in a murine model of peripheral neuropathic pain. MiRNAs are small, non-coding RNAs known to play a crucial role in post-transcriptional gene regulation, mainly in cell proliferation and differentiation. Initially, expression patterns in affected dorsal root ganglia (DRG) at different time points after setting a peripheral nerve lesion were studied. DRG showed an increasingly differential expression pattern over the course of one week. Interestingly, a similar effect, albeit to a smaller extent, was observed in corresponding contralateral ganglia. Five miRNA (miR-124, miR-137, miR-183, miR-27b, and miR-505) were further analysed. qPCR, in situ hybridization, and bioinformatical analysis point towards a role for miR-137 and -183 in neuropathic pain as both were downregulated. Furthermore, miR-137 is shown to be specific for non-peptidergic non-myelinated nociceptors (C fibres) in DRG. As the ganglia consist of highly heterocellular tissue, I also developed a neuron-specific approach. Primarily damaged neurons were separated from intact adjacent neurons using fluorescence-activated cell-sorting and their gene expression pattern was analysed using a microarray. Thereby, not only were information obtained about mRNA expression in both groups but, by bioinformatical tools, also inferences on miRNA involvement. The general expression pattern was consistent with previous findings. Still, several genes were found differentially expressed that had not been described in this context before. Among these are corticoliberin or cation-regulating proteins like Otopetrin1. Bioinformatical data conformed, in part, to results from whole DRG, e.g. they implied a down-regulation of miR-124, -137, and -183. However, these results were not significant. In summary, I found that a) miRNA expression in DRG is influenced by nerve lesions typical of neuropathic pain and that b) these changes develop simultaneously to over-expression of galanin, a marker for neuronal damage. Furthermore, several miRNAs (miR-183, -137) exhibit distinct expression patterns in whole-DRG as well as in neuron-specific approaches. Therefore, further investigation of their possible role in initiation and maintenance of neuropathic pain seems promising. Finally, the differential expression of genes like Corticoliberin or Otopetrin 1, previously not described in neuropathic pain, has already resulted in follow-up projects.},
  subject      = {Schmerzforschung},
  language  = {en}
}
@phdthesis{BenKraiem2023,
  author    = {Ben-Kraiem, Adel},
  title     = {Temporal characterization of the blood nerve barrier and specialized pro resolving mediators as therapeutic targets in neuropathy},
  doi       = {10.25972/OPUS-32079},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-320797},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Abstract Neuropathic pain affects 6.9 to 10\% of the general population, arises from lesion or disease of the somatosensory nervous system and is still challenging to treat. Indeed, current treatments efficacy are relatively low and present strong side effects. To that extent, identifying new targets and developing new treatment strategies constitute a priority. The blood nerve barrier consists of the endoneurial micro-blood vessels and the perineurium sealed by tight junctions constituted of tight junction proteins such claudin-5 and claudin-1. As the functional blood nerve barrier allows nerve tissue protection from external elements and maintains homeostasis, a destabilization or a disruption leads to infiltration of immunocytes promoting neuroinflammation and increased inflammatory mediators that can sensitize nociceptors and enhance pain. Thus resealing the blood nerve barrier in case of neuropathic pain could be a possible treatment strategy. Specialised proresolving mediators such lipoxin A4 and resolvin D1 are small lipids that bind to receptors such the formylpeptide recptor 2 (FPR2) and resolve inflammation. Specially resolvin D1 as anti-inflammatory and analgesic properties. Thus using resolvin D1 or eventually other specialized proresolving mediators in neuropathic pain could reseal the blood nerve barrier and resolve neuropathic pain. The present work aimed to characterize the blood nerve barrier in a preclinical model of diabetic polyneuropathy and nerve injury (chronic constriction injury) and to identify specialized proresolving mediators that seal the blood nerve barrier and thereby alleviate neuropathic pain. In diabetic polyneuropathy, the blood nerve barrier is permeable only to small molecules, which is due to the loss of claudin-1 in the perineurium and a reduced number of blood vessel- associated macrophages. Interestingly, blood nerve barrier permeability did not occur until four to eight weeks after diabetes induction, whereas mechanical hyperalgesia was measurable as early as two weeks. This suggests a pain-maintaining rather than a pain-triggering role of the blood nerve barrier. In case of chronic constriction injury, a resolution process of both mechanical and thermal hyperalgesia occurs between three to six weeks after injury. Here, the blood nerve barrier is permeable to both small and large molecules from the beginning. The pain recovery process occurs primarily in parallel with the sealing of the endoneurial barrier to large molecules such as fibrinogen from the plasma and its degradation. Perineurium is still permeable nine weeks after injury. Metabolomic analyses show that especially precursors of Resolvin D1 as well as its receptor FPR2, are upregulated at the beginning of pain resolution. Application of resolvin D1 loaded nanoparticles or agonists of FPR2 at the injury site before the onset of pain resolution accelerates the process and fibrinogen is no longer detectable in the endoneurium. Depending on the nerve damage, the blood nerve barrier is affected to varying degrees. Direct mechanical trauma and the accompanying inflammation lead to a more pronounced and long-lasting permeability - independent hyperalgesia. Possibly permeability, at least for small molecules, is important for prolonged reparative processes. In the nerve, permeability of capillaries in particular depends not only on tight junctions but also on other cells: in addition to macrophages, pericytes could also have a sealing effect. Endoneurial fibrinogen triggers pain; the exact mechanism remains to be investigated. Resolvin-containing nanoparticles were particularly effective and could be used locally as they contain endogenous substances in non- toxic particles.},
  language  = {en}
}