The alternatively spliced fibronectin CS1 isoform regulates IL-17A levels and mechanical allodynia after peripheral nerve injury.
BACKGROUND
Mechanical pain hypersensitivity associated with physical trauma to peripheral nerve depends on T-helper (Th) cells expressing the algesic cytokine, interleukin (IL)-17A. Fibronectin (FN) isoform alternatively spliced within the IIICS region encoding the 25-residue-long connecting segment 1 (CS1) regulates T cell recruitment to the sites of inflammation. Herein, we analyzed the role of CS1-containing FN (FN-CS1) in IL-17A expression and pain after peripheral nerve damage.


METHODS
Mass spectrometry, immunoblotting, and FN-CS1-specific immunofluorescence analyses were employed to examine FN expression after chronic constriction injury (CCI) in rat sciatic nerves. The acute intra-sciatic nerve injection of the synthetic CS1 peptide (a competitive inhibitor of the FN-CS1/α4 integrin binding) was used to elucidate the functional significance of FN-CS1 in mechanical and thermal pain hypersensitivity and IL-17A expression (by quantitative Taqman RT-PCR) after CCI. The CS1 peptide effects were analyzed in cultured primary Schwann cells, the major source of FN-CS1 in CCI nerves.


RESULTS
Following CCI, FN expression in sciatic nerve increased with the dominant FN-CS1 deposition in endothelial cells, Schwann cells, and macrophages. Acute CS1 therapy attenuated mechanical allodynia (pain from innocuous stimulation) but not thermal hyperalgesia and reduced the levels of IL-17A expression in the injured nerve. CS1 peptide inhibited the LPS- or starvation-stimulated activation of the stress ERK/MAPK pathway in cultured Schwann cells.


CONCLUSIONS
After physical trauma to the peripheral nerve, FN-CS1 contributes to mechanical pain hypersensitivity by increasing the number of IL-17A-expressing (presumably, Th17) cells. CS1 peptide therapy can be developed for pharmacological control of neuropathic pain.
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. hliu@salk.edu.|VA San Diego Healthcare System, La Jolla, CA, USA. hliu@salk.edu.
Huaqing
H
Liu
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. jdolkas@ucsd.edu.|VA San Diego Healthcare System, La Jolla, CA, USA. jdolkas@ucsd.edu.
Jennifer
J
Dolkas
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. donatelife74@hotmail.com.|VA San Diego Healthcare System, La Jolla, CA, USA. donatelife74@hotmail.com.
Khan
K
Hoang
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. mangert@ucsd.edu.|VA San Diego Healthcare System, La Jolla, CA, USA. mangert@ucsd.edu.
Mila
M
Angert
Sanford-Burnham Medical Research Institute, La Jolla, CA, USA. achernov@sanfordburnham.org.
Andrei V
AV
Chernov
Sanford-Burnham Medical Research Institute, La Jolla, CA, USA. aremacle@sanfordburnham.org.
Albert G
AG
Remacle
Sanford-Burnham Medical Research Institute, La Jolla, CA, USA. shiryaev@sanfordburnham.org.
Sergey A
SA
Shiryaev
Sanford-Burnham Medical Research Institute, La Jolla, CA, USA. strongin@sanfordburnham.org.
Alex Y
AY
Strongin
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. ntasukuk@yahoo.co.jp.|VA San Diego Healthcare System, La Jolla, CA, USA. ntasukuk@yahoo.co.jp.
Tasuku
T
Nishihara
Department of Anesthesiology, University of California, 9500 Gilman Dr., Mail Code 0629, La Jolla, San Diego, CA, 92093-0629, USA. vshubayev@ucsd.edu.|VA San Diego Healthcare System, La Jolla, CA, USA. vshubayev@ucsd.edu.
Veronica I
VI
Shubayev
D000818:Animals; D000831:Animals, Newborn; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D020381:Interleukin-17 / Q000235:genetics / Q000378:metabolism*; D010147:Pain Measurement; D010455:Peptides / Q000378:metabolism* / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D012583:Schwann Cells / Q000378:metabolism; D012584:Sciatic Nerve / Q000187:drug effects / Q000378:metabolism; D020426:Sciatic Neuropathy / Q000150:complications* / Q000473:pathology; D013997:Time Factors; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D048049:Extracellular Signal-Regulated MAP Kinases; D036341:Intercellular Signaling Peptides and Proteins; D020381:Interleukin-17; D010455:Peptides; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C076687:CS1 peptide