Frontline: Inhibition of allergen-induced pulmonary inflammation by the tripeptide feG: a mimetic of a neuro-endocrine pathway

Abstract

Interactions between the neuro-endocrine system and immune system help maintain health. One interaction involves the superior cervical ganglia (SCG), which regulate the prohormone submandibular rat 1 (SMR1) produced by the submandibular gland (SMG). A peptide derived from SMR1, feG, has anti-inflammatory activity, and modification to D-isomer feG enhances bioactivity. We tested feG as a therapeutic agent for airways inflammation, using rats sensitized by OVA or Nippostrongylus brasiliensis (Nb). Treatment with feG but not fdG down-regulated OVA-challenge-induced increases in bronchoalveolar lavage (BAL)-derived macrophages, eosinophils and PMN (neutrophils) by 44%, 69% and 67%, respectively, at 24 h. We found that feG also reduced ICAM-1 on BAL-derived macrophages and eosinophils by 27% and 65%, and L-selectin on PMN by 55% following OVA challenge. Furthermore, feG but not fdG reduced the OVA-induced TNF increase in BAL fluid. We showed that feG also down-regulated both hyper-responsiveness to methacholine (by 27%) and microgranulomata formation in the lung parenchyma. In Nb-challenged rats, feG treatment inhibited ex vivo allergen-induced contraction of tracheal smooth muscle by up to 73%. In conclusion, feG, which is a mimetic of a peptide derived from a rat salivary gland prohormone, has anti-inflammatory properties in allergic airways inflammation in Brown-Norway rats. The role of the SCG-SMG neuro-endocrine pathway in allergic asthma and other inflammatory diseases requires additional study.