B Lymphocytes Express Pomc mRNA, Processing Enzymes and β-Endorphin in Painful Inflammation

J Neuroimmune Pharmacol. 2017 Mar;12(1):180-186. doi: 10.1007/s11481-016-9715-4. Epub 2016 Nov 11.


Immune cell-derived beta-endorphin (END) and other opioid peptides elicit potent and clinically relevant inhibition of pain (analgesia) in inflamed tissue by activation of peripheral opioid receptors. Pro-opiomelanocortin (POMC) is the polypeptide precursor of END and is processed by prohormone convertases (PCs). This study aims to decipher the processing of POMC in lymphocyte subsets in a rat model of unilateral painful hindpaw inflammation. Lymphocytes, isolated from popliteal lymph nodes, were separated into B-cells, T-cells, T-helper cells and cytotoxic T-cells using magnetic cell sorting, and were examined by polymerase chain reaction, immunofluorescence and radioimmunoassay. At 2 h of inflammation, POMC exon 2-3 mRNA was mostly expressed in B- but not in T-cells. Prohormone convertase 1 (PC1) mRNA and protein were upregulated in B-cells and T-helper cells. Prohormone convertase 2 (PC2) was expressed in T- and B-cells, both in inflamed and non-inflamed lymph nodes. END was expressed in B- but not in T-cells. We conclude that POMC, its processing enzymes and END are predominantly expressed in B-lymphocytes at 2 h of paw inflammation.

Keywords: Endorphin; Inflammation; Lymphocytes; Opioid; Pain; Prohormone convertase; Proopiomelanocortin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / enzymology
  • B-Lymphocytes / metabolism*
  • Gene Expression
  • Inflammation / genetics
  • Inflammation / metabolism
  • Male
  • Pain / genetics
  • Pain / metabolism*
  • Pro-Opiomelanocortin / biosynthesis*
  • Pro-Opiomelanocortin / genetics
  • Proprotein Convertase 1 / biosynthesis
  • Proprotein Convertase 1 / genetics
  • Proprotein Convertase 2 / biosynthesis
  • Proprotein Convertase 2 / genetics
  • RNA, Messenger / biosynthesis*
  • RNA, Messenger / genetics
  • Rats
  • Rats, Wistar
  • Serine Endopeptidases / biosynthesis*
  • Serine Endopeptidases / genetics
  • beta-Endorphin / biosynthesis*
  • beta-Endorphin / genetics


  • RNA, Messenger
  • beta-Endorphin
  • Pro-Opiomelanocortin
  • Serine Endopeptidases
  • Proprotein Convertase 1
  • Proprotein Convertase 2