Studies On Immunomodulatory Activity Of Lectin From Musca Domestica Pupae In B Cells

Lectins are proteins that bind carbohydrates with considerable specificity and usually agglutinate cells. Because they can recognize residues of glycoconjugates on the surface of cells by recognizing sequences of two or more saccharides with specificity toward both interresidue glycosidic linkages and also anomeric configuration, they could involved in many numerous important biological phenomena. Musca domestica is a kind of insect which lives in environments full of pathogens. So they are identified as transport hosts for a variety of zoonosis. But it possibly possesses efficient defense mechanisms for survival.A novel lectin had been purified from Musca domestica Pupae (MPL) using affinity chromatography and anion exchange chromatography. After affinity chromatography on a D-galactose-Sepharose-4B column, four protein bands were got by SDS-PAGE analyses. Then further separated by DEAE-Sepharose Fast Flow, four fractions were got, designated as MPL-1, MPL-2, MPL-3and MPL-4. According to the proliferation effect of MPL-3on B cells and the activity of agglutinate rabbit blood cells, the activity of MPL-3was maximum. Our studies found that MPL-3was a lectin with a molecular weight of43kDa. And the content of protein and oligosaccharide was97.2%and2.72%respectively. In our study, we also found that MPL-3significantly promoted the proliferation of B cells in a dose-dependent manner, but not in a time-dependent manner. MPL-3also could enhance the expression of IL-6, IL-12and IFN-y. To further elucidate the underlying mechanism, ERK1/2and NF-κB signaling pathways were assessed. MPL could stimulates the phosphorylation of ERK1/2. Moreover, it also could induce1κB-α degradation and NF-κB translocation. The proliferation of cells and the expression of IL-12were significantly inhibited by ERK1/2inhibitor (PD98059) and NF-κB inhibitor (PDTC). PD98059could inhibit the expression of NF-κB in nucleus, while PDTC could not inhibit the phosphorylation of ERK1/2. The results suggested that MPL regulated the cell proliferation and induced IL-12production through ERK1/2-NF-κB signaling pathway. Therefore, the results demonstrated that MPL-3could stimulates the B cells proliferation and enhances IL-16. IL-12and IFN-y production via ERK1/2-NF-κB signaling pathway, which provide certain reference basis for the development of natural immunopotentiator.