Immune responses to recombinant Brugia malayi pepsin inhibitor homolog (Bm-33) in patients with human lymphatic filariaisis

Abstract

Immune responses to recombinant Brugia malayi pepsin inhibitor homolog (rBm-33) were investigated in patients with human lymphatic filariasis (microfilaremics (MF) and chronic pathology (CP)) along with endemic normals (EN). Flow cytometric analysis (24 h) revealed CD4+ T cell activation in patients (MF and CP) compared to normals (EN), with increased expression of CD69 and diminished levels of CD62L and CD127. This was associated with an elevated expression of CD154 but not CD28 and CTLA4 in CP patients. However, Bm-33-induced cytokine expression profile (IL-1β, IL-12, IL-8, IFN-γ, IL-10 and TGF-β) did not exhibit any significant difference between normals and patients at the same time point. Although CD4+ T cell activation was observed initially in filarial patients (24 h), lymphoproliferation studies (96 h) suggested diminished proliferation compared to normals, indicating functional inactivation in the former upon prolonged antigen exposure. This indicates that rBm-33 induces an early T cell activation in MF and CP patients followed by a decreased lymphoproliferation that might contribute to immune suppression in these individuals.

Physicochemical characterization of an aspin (rBm-33) from a filarial parasiteBrugia malayiagainst the important human aspartic proteases

“…rBm-33 is an aspartic protease inhibitor secreted by the human filarial parasite Brugia malayi and is believed to play a key role in host pathogenesis and immune modulation 18 . It was purified under denaturing conditions and refolded by step wise dialysis using buffers of pH ranging from 11 to 7.…”

“…Among these the best characterized one is the aspin (PI-3) from the nonfilarial nematode Ascaris suum that infects the pigs 15 . Similarly, an aspin (Bm-33) from the filarial nematode Brugia malayi has also been identified and the immunological characterizations have been reported [16][17][18] . In addition to this, the earlier studies from this laboratory reveal rBm-33 to be a human pepsin inhibitor 19 .…”

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

“…Studies with several experimental models suggested the role of CD 4 + T cells apoptosis in proliferative defect associated with the filarial patients [35,36]. We have previously shown using PBMCs that rBm33 induced unsustained early T cell activation in the MF individuals and one possibility for this could be the apoptosis of T cells in such individuals [12]. Similar studies have been carried out previously with live L3 microfilariae of B. malayi , which showed early Natural killer cell activation followed by NK cell apoptosis [37].…”

“…PBMCs were isolated from heparinized venous blood from five endemic normals by density centrifugation as described previously [12]. Cells obtained by Ficoll-Hypaque density centrifugation were suspended in complete RPMI 1640 medium and the cells were counted in hemocytometer by trypan blue exclusion and seeded in culture plates.…”

“…Bm33 was produced using recombinant technology (rBm33) and was characterized to show high levels of antigen specific IgG4 antibodies in microfilaria positive individuals compared to the patients with chronic pathology [11]. Further, rBm33 induced early T cell activation in MF and CP patients followed by a decreased lymphoproliferation that contributes to the immune modulation in these individuals [12]. …”