Methods: From an A. lumbricoides cDNA library we obtained an E. coli produced recombinant cystatin (rAl-CPI). Protease activity inhibition was tested on cathepsin B and papain. Immunomodulatory effects were evaluated at two doses, administered intraperitoneally (0.5 and 0.25 µg/g) on mice with chemically induced (4% Dextran Sodium Sulphate, DSS) - IBD. Body weight, colon length, disease activity index (DAI), histological inflammation score, myeloperoxidase (MPO) activity and gene expression of six cytokines in colon tissue were analyzed.
Results: rAl-CPI showed biological activity. The treatment with rAl-CPI significantly reduced DAI, MPO activity and inflammation score, without toxic effects. Also, IL-10 (p<0.0001) and TGFβ (p=0.001) gene overexpression was observed in rAl-CPI treated (both concentrations) compared to DSS-exposed animals and healthy (PBS) group. Furthermore, a significant reduction of IL-6 (p<0.001) and TNFα (p<0.01) expression, key mediators of IBD, was observed. Although lower expression of IL-1β and IL-12 was detected, it was not statistically significant.
Conclusions: rAl-CPI reduces the inflammation in a mouse model of IBD, probably by increasing the expression of anti-inflammatory cytokines and reducing pro-inflammatory ones. The usefulness of this recombinant protein in respiratory inflammation should be further investigated.