@article{ChenSchmidtSchuergeretal.2021,
  author    = {Chen, Jeremy Tsung-Chieh and Schmidt, Lea and Sch{\"u}rger, Christina and Hankir, Mohammed K. and Krug, Susanne M. and Rittner, Heike L.},
  title     = {Netrin-1 as a multitarget barrier stabilizer in the peripheral nerve after injury},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {18},
  issn      = {1422-0067},
  doi       = {10.3390/ijms221810090},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261695},
  year      = {2021},
  abstract  = {The blood-nerve barrier and myelin barrier normally shield peripheral nerves from potentially harmful insults. They are broken down during nerve injury, which contributes to neuronal damage. Netrin-1 is a neuronal guidance protein with various established functions in the peripheral and central nervous systems; however, its role in regulating barrier integrity and pain processing after nerve injury is poorly understood. Here, we show that chronic constriction injury (CCI) in Wistar rats reduced netrin-1 protein and the netrin-1 receptor neogenin-1 (Neo1) in the sciatic nerve. Replacement of netrin-1 via systemic or local administration of the recombinant protein rescued injury-induced nociceptive hypersensitivity. This was prevented by siRNA-mediated knockdown of Neo1 in the sciatic nerve. Mechanistically, netrin-1 restored endothelial and myelin, but not perineural, barrier function as measured by fluorescent dye or fibrinogen penetration. Netrin-1 also reversed the decline in the tight junction proteins claudin-5 and claudin-19 in the sciatic nerve caused by CCI. Our findings emphasize the role of the endothelial and myelin barriers in pain processing after nerve damage and reveal that exogenous netrin-1 restores their function to mitigate CCI-induced hypersensitivity via Neo1. The netrin-1-neogenin-1 signaling pathway may thus represent a multi-target barrier protector for the treatment of neuropathic pain.},
  language  = {en}
}
@article{LuxHuBenKraiemetal.2019,
  author    = {Lux, Thomas J. and Hu, Xiawei and Ben-Kraiem, Adel and Blum, Robert and Chen, Jeremy Tsung-Chieh and Rittner, Heike L.},
  title     = {Regional differences in tight junction protein expression in the blood-DRG barrier and their alterations after nerve traumatic injury in rats},
  series = {International Journal of Molecular Sciences},
  volume    = {21},
  journal   = {International Journal of Molecular Sciences},
  number    = {1},
  issn      = {1422-0067},
  doi       = {10.3390/ijms21010270},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285029},
  year      = {2019},
  abstract  = {The nervous system is shielded by special barriers. Nerve injury results in blood-nerve barrier breakdown with downregulation of certain tight junction proteins accompanying the painful neuropathic phenotype. The dorsal root ganglion (DRG) consists of a neuron-rich region (NRR, somata of somatosensory and nociceptive neurons) and a fibre-rich region (FRR), and their putative epi-/perineurium (EPN). Here, we analysed blood-DRG barrier (BDB) properties in these physiologically distinct regions in Wistar rats after chronic constriction injury (CCI). Cldn5, Cldn12, and Tjp1 (rats) mRNA were downregulated 1 week after traumatic nerve injury. Claudin-1 immunoreactivity (IR) found in the EPN, claudin-19-IR in the FRR, and ZO-1-IR in FRR-EPN were unaltered after CCI. However, laser-assisted, vessel specific qPCR, and IR studies confirmed a significant loss of claudin-5 in the NRR. The NRR was three-times more permeable compared to the FRR for high and low molecular weight markers. NRR permeability was not further increased 1-week after CCI, but significantly more CD68\(^+\) macrophages had migrated into the NRR. In summary, NRR and FRR are different in na{\"i}ve rats. Short-term traumatic nerve injury leaves the already highly permeable BDB in the NRR unaltered for small and large molecules. Claudin-5 is downregulated in the NRR. This could facilitate macrophage invasion, and thereby neuronal sensitisation and hyperalgesia. Targeting the stabilisation of claudin-5 in microvessels and the BDB barrier could be a future approach for neuropathic pain therapy.},
  language  = {en}
}