Entamoeba histolytica in culture produces a pentapeptide (MQCNS). This
oligopeptide inhibits the in vitro and in vivo locomotion of human monocytes, hence its denomination
Monocyte Locomotion Inhibitory Factor (
MLIF). The original isolated
peptide and its synthetic construct display similar effects, among others, being inhibition of the respiratory burst in monocytes and neutrophils, decrease of
Dinitrochlorobenzene (
DNCB) skin
hypersensitivity in guinea pigs and gerbils, and delay of mononuclear leukocytes in human Rebuck skin windows with inhibition of vascular cell Very late
antigen (VLA)-4 and Vascular adhesion molecules (VCAM) in endothelia and monocytes. The
MLIF molecular mechanism of action is unknown, but data reveal its implication in
Nuclear factor-kappa B (NF-κB) and Mitogenactivated
protein kinase (MAPK) pathways. This could explain
MLIF multiplicity of
biological effects. On the other hand, the amebic
peptide has been useful in treating experimental
amebiasis of the liver. The amebic
peptide is effective in reducing
inflammation induced by carragenin and
arthritis in a
Collagen-induced arthritis (CIA) model. Microarray data from
experimental arthritis revealed an
MLIF gene expression profile that includes genes that are involved in apoptosis, cell adhesion, extracellular matrix, and
inflammation / chemotaxis.
MLIF could be involved in unsuspected
biological factions because there is increasing data on the
peptide effect on several cell activities. This review also presents uses of
MLIF as described in patents.