Recombinant Brugia malayi pepsin inhibitor (rBm33) induced monocyte function and absence of apoptotic cell death: An in vitro study

The effect of recombinant Brugia malayi pepsin inhibitor (rBm33) on human monocytes/macrophages has been examined using THP-1 cells. THP-1 cells stimulated with rBm33 showed enhanced levels of expression of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6) and diminished levels of IL-12, iNOS and anti-inflammatory cytokine (IL-10) expression suggesting the predominant features of Th1 response. Phorbol-12-myristate-13-acetate (PMA) treated THP-1 cells stimulated with rBm33 and subsequent incubation with GFP expressing Escherichia coli (E. coli) for 2 h enhanced the uptake of E. coli. Nitric oxide (NO) levels measured in the supernatants of these cultures did not show significant changes. Apoptotic studies with Peripheral Blood Mononuclear Cells (PBMCs) from normal individuals stimulated with rBm33 did not induce apoptosis of monocytes or lymphocytes. These observations suggest that rBm33 stimulates macrophages to induce Th1 response and does not promote apoptosis.

Highlights► Recombinant Bm33 induces predominantly Th1 responses in THP-1 monocytes. ► Recombinant Bm33 enhances the uptake of Escherichia coli by THP-1 macrophages. ► Recombinant Bm33 does not induce apoptosis in monocytes of endemic normal individuals.