Methionine Enkephalin: A New Cytokine—Human Studies

Lipopolysaccharide mediated regulation of neuroendocrine associated proprotein convertases and neuropeptide precursor processing in the rat spleen

“…This is in line with the data we previously demonstrated in monocytes during interleukin-6 stimulation (22). PENK processing after immune response stimulation allows the production of the antibacterial peptide enkelytin which is found in phagolysosomes (22) whereas Met-Enk, Met-Enk RF are released in order to stimulate chemotaxis (19) and act as cytokines (47). It is also interestingly to note that in non-stimulated animals, the oxidized forms of enkephalin derived peptides are high compared to injected animals.…”

“…Differential processing of PENK by the PCs appears to generate multiple biological activities in immune cells. The opioid Met-Enk and its analogs, through their delta opioid receptor activities can enhance the immune reaction by stimulating immunocyte chemotaxis, phagocytosis and secretion of immunostimulatory factors, but would also mediate an analgesic effect in peripheral inflamed tissues (18,47,49,50). Furthermore, the release of enkelytin and Met-Enk peptides is increased in different cases such as LPS injection, surgical trauma or bacterial exposure (19,24).…”

Characterization of Antibacterial COOH-terminal Proenkephalin-A-derived Peptides (PEAP) in Infectious Fluids

“…Met-enkephalin enhances the immune reaction in patients with cancer or AIDS (77). With regard to this immune modulating property, Metenkephalin has been proposed to be classified as a cytokine (78). Moreover, this pentapeptide can bind opioid receptors present in peripheral inflammed tissues to mediate an analgesic effect (79).…”

The Evolution of Fangs, Venom, and Mimicry Systems in Blenny Fishes

“…While the group X class of PLA 2 s has not previously been described from any venom, they are known to promote inflammatory pathology [18,19]. and inflammatory responses [22][23][24]. To test for opioid activity, we screened fangblenny venom against human embryonic kidney 293 (HEK) cells expressing µ-, κ-and δ-subtype opioid receptors.…”