A novel peptide able to reduce PLA2 activity and modulate inflammatory cytokine production.

Phospholipases A2 (PLA2s) are associated with inflammatory response, performing a complex process involving, specially, cytokines. The excess of pro-inflammatory cytokines induces a chronic inflammatory response and can cause several disorders in the body. Therefore, the inhibition or regulation of cytokines' signaling pathways is a target for new treatment development strategies. Thus, this study aimed to select PLA2 inhibitor mimetic peptides through phage display technology with anti-inflammatory activity. Specific mimetic peptides were selected using BpPLA2-TXI, a PLA2 isolated from Bothrops pauloensis, as a target, and γCdcPL, a PLA2 inhibitor isolated from Crotalus durissus collilineatus, which was used as a competitor during the elution step. We selected the peptide C2PD, which seems to play a pivotal role in the modulation of IL-6, IL-1ß, and IL-10 cytokines in inflammatory cells. The C2PD showed a significant reduction in PLA2 activity. Furthermore, the synthetic peptide was tested in PBMC and showed a significant down-modulation of IL-6 and IL-1ß release, whereas IL-10 responses were up-regulated. Our findings suggest that this novel peptide may be a potential therapeutic candidate for the treatment of inflammatory diseases, mainly due to its anti-inflammatory properties and absence of cytotoxicity.

Structural and functional characterization of a novel scFv anti-HSP60 of Strongyloides sp.

Phage display is a powerful technology that selects specific proteins or peptides to a target. We have used Phage Display to select scFv (single-chain variable fragment) clones from a combinatorial library against total proteins of Strongyloides venezuelensis. After scFv characterization, further analysis demonstrated that this recombinant fragment of antibody was able to bind to an S. venezuelensis antigenic fraction of ~65 kDa, present in the body periphery and digestive system of infective larvae (L3), as demonstrated by immunofluorescence. Mass spectrometry results followed by bioinformatics analysis showed that this antigenic fraction was a heat shock protein 60 (HSP60) of Strongyloides sp. The selected scFv was applied in serodiagnosis by immune complexes detection in serum samples from individuals with strongyloidiasis using a sandwich enzyme-linked immunosorbent assay (ELISA), showing sensitivity of 97.5% (86.84-99.94), specificity of 98.81 (93.54-99.97), positive likelihood ratio of 81.60 and an area under the curve of 0.9993 (0.9973-1.000). Our study provided a novel monoclonal scFv antibody fragment which specifically bound to HSP60 of Strongyloides sp. and was applied in the development of an innovative serodiagnosis method for the human strongyloidiasis.