Macrophage migration inhibitory factor of the parasitic nematode Trichinella spiralis

Abstract

cDNAs were obtained for macrophage migration-inhibitory factor (MIF)/l-dopachrome methyl ester tautomerase homologues from the parasitic nematodes Trichinella spiralis (TsMIF) and Trichuris trichiura (TtMIF). The translated sequences, which were partly confirmed by sequencing of proteolytic fragments, show 42 and 44% identity respectively with human or mouse MIF, and are shorter by one C-terminal residue. Unlike vertebrate MIF and MIF homologues of filarial nematodes, neither TsMIF nor TtMIF contain cysteine residues. Soluble recombinant TsMIF, expressed in Escherichia coli showed secondary structure (by CD spectroscopy) and quaternary structure (by light-scattering and gel filtration) similar to that of the trimeric mammalian MIFs and d-dopachrome tautomerase. The catalytic specificity of recombinant TsMIF in the ketonization of phenylpyruvate (1.4×106M−1·s−1) was comparable with that of human MIF, while that of p-hydroxyphenylpyruvate (9.1×104M−1·s−1) was 71-fold lower. TsMIF showed high specificity in tautomerization of the methyl ester of l-dopachrome compared with non-esterified l-dopachrome (>87000-fold) and a high kcat (≈ 4×104s−1). The crystal structure, determined to 1.65 Å (1 Å = 0.1nm), was generally similar to that of human MIF, but differed in the boundaries of the putative active-site pocket, which can explain the low activity towards p-hydroxyphenylpyruvate. The central pore was blocked, but was continuous, with the three putative tautomerase sites. Recombinant TsMIF (5ng/ml–5pg/ml) inhibited migration of human peripheral-blood mononuclear cells in a manner similar to that shown by human MIF, but had no effect from 5 to 500ng/ml on anti-CD3-stimulated murine T-cell proliferation. TsMIF was detected in supernatants of T. spiralis larvae cultured in vitro at 6ng/ml (55ng/mg total secreted protein). In conclusion TsMIF has structural, catalytic and cell-migration-inhibitory properties which indicate that it is partially orthologous to mammalian MIF.

Characterization of host-parasite interactions during the experimental Trichinella spiralis infection in pigs

“…In another experiment performed with T. britovi (15000 larvae) on pigs, CPK, AST and ALT presented increased activity during the infection (Oltean et al, 2009). The irrelevant results obtained in the phagocytic assay could be explained through the results obtained by Pennock et al (1998), Tan et al (2001) and Freitas and Pearce (2010), who demonstrated the presence of a macrophage migration-inhibitory factor (MIF) in T. spiralis larvae, very similar to a mammalian cytokine, which might contribute to subversion of host defences. The mammalian MIF is inhibitory for monocyte-macrophage migration, towards glucocorticoid activity (Calandra et al, 1995), immunoglobulin synthesis (Tomura et al, 1999) and natural killer-cell activity (Apte et al, 1998), but not all this properties have been demonstrated yet in MIF produced by T. spiralis.…”

The Immune Response to Nematode Infection

“…In clade I, the order Trichinellida contains the families Trichinellidae and Trichuridae, which contain the genera Trichinella and Trichuris, respectively. Trichinella spiralis secretes a mimic of macrophage migration inhibitory factor [85].…”

Nematode Orthologs of Macrophage Migration Inhibitory Factor (MIF) as Modulators of the Host Immune Response and Potential Therapeutic Targets

“…This effect was confirmed via neutralizing anti-MIF antibodies which restored the migration of cells. Similarly to Bm-MIF, recombinant T. spiralis MIF (TsMIF) inhibited the migration of human peripheral blood mononuclear cells (PBMCs) [70].…”