@article{ReinholdKrugSalvadoretal.2022,
  author    = {Reinhold, Ann Kristin and Krug, Susanne M. and Salvador, Ellaine and Sauer, Reine S. and Karl-Sch{\"o}ller, Franziska and Malcangio, Marzia and Sommer, Claudia and Rittner, Heike L.},
  title     = {MicroRNA-21-5p functions via RECK/MMP9 as a proalgesic regulator of the blood nerve barrier in nerve injury},
  series = {Annals of the New York Academy of Sciences},
  volume    = {1515},
  journal   = {Annals of the New York Academy of Sciences},
  number    = {1},
  doi       = {10.1111/nyas.14816},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318226},
  pages     = {184 -- 195},
  year      = {2022},
  abstract  = {Both nerve injury and complex regional pain syndrome (CRPS) can result in chronic pain. In traumatic neuropathy, the blood nerve barrier (BNB) shielding the nerve is impaired—partly due to dysregulated microRNAs (miRNAs). Upregulation of microRNA-21-5p (miR-21) has previously been documented in neuropathic pain, predominantly due to its proinflammatory features. However, little is known about other functions. Here, we characterized miR-21 in neuropathic pain and its impact on the BNB in a human-murine back translational approach. MiR-21 expression was elevated in plasma of patients with CRPS as well as in nerves of mice after transient and persistent nerve injury. Mice presented with BNB leakage, as well as loss of claudin-1 in both injured and spared nerves. Moreover, the putative miR-21 target RECK was decreased and downstream Mmp9 upregulated, as was Tgfb. In vitro experiments in human epithelial cells confirmed a downregulation of CLDN1 by miR-21 mimics via inhibition of the RECK/MMP9 pathway but not TGFB. Perineurial miR-21 mimic application in mice elicited mechanical hypersensitivity, while local inhibition of miR-21 after nerve injury reversed it. In summary, the data support a novel role for miR-21, independent of prior inflammation, in elicitation of pain and impairment of the BNB via RECK/MMP9.},
  language  = {en}
}
@phdthesis{Hu2021,
  author    = {Hu, Xiawei},
  title     = {Role of claudin-12 in neuronal barriers in painful murine and human neuropathy},
  doi       = {10.25972/OPUS-20806},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208065},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {In peripheral nervous system (PNS), the blood-nerve barrier (BNB) and myelin barrier (MB) are important physiological fences for maintaining the environment for axons, Schwann cells and other associated cells within peripheral nerves. The perineurium surrounding the nerves and endoneurial vessels nourishing the nerves compose the BNB. Schwann cells wrapping around neurons form the MB. Destruction or malfunction of the barriers has been postulated as an initial step in the development of pathologic conditions concerning human peripheral nerves, such as traumatic neuropathy and the disease of chronic inflammatory demyelination polyneuropathy (CIDP). Tight junction proteins (TJPs) are intercellular junctions building the microstructure of barriers. They play a key role in tightly connecting adjacent cells, controlling the passage of ions, water and other molecules via the paracellular pathway, and maintaining the cell polarity. Among the family of TJPs, claudins are the major structural components which form the backbone of TJs. Certain key TJPs [e.g. claudins (claudin-1, -5, -19, occludin, zona occludens (ZO-1)] have been identified in neural barriers and explored for therapeutic targets. The expression of Cldn12 gene has been documented in human/rodent tibial nerves, spinal cord and DRG. However, the role of claudin-12 in PNS is unknown. In the present study, we firstly found a loss of claudin-12 immunoreactivity (IR) in male or postmenopausal female patients with painful CIDP or non-inflammatory polyneuropathy (PNP). Then, we utilized male and female Cldn12-KO mice and the chronic constriction injury (CCI) model. Cldn12 mRNA and IR were reduced in WT mice after nerve injury. Deletion of Cldn12 via general knockout (KO) induced mechanical allodynia at baseline level and after CCI in time-dependent manner in male mice. KO of Cldn12 in males resulted in loss of small axons, perineurial barrier and MB breakdown, as well as TJP complex disruption with claudin-1, -19 and Pmp22 reduction. Moreover, local Cldn12 siRNA application mimicked mechanical allodynia and MB breakdown. In conclusion, claudin-12 deficiency is associated with painful CIDP/non-inflammatory PNP. Claudin-12 is a regulatory TJP crucial for mechanical nociception, perineurial barrier and MB integrity, and proper TJP composition in mice. Therefore, further investigating the functions of claudin-12 and its mechanism is important to prompt the development of new therapeutic approaches for painful neuropathies.},
  language  = {en}
}