In silico analysis of two Haemonchus spp. serine protease peptides (S28) and their immunomodulatory activity in vitro.

The aim of this study was to evaluate the in vitro immune modulation of two de novo peptides with hypothetical identity to the serine protease family (S28) from Haemonchus spp. Expression of mRNAs encoding these peptides was confirmed by RTqPCR in L3 and adult stage parasites. Antibodies from serum samples collected from an H. contortus-infected lamb at 60 days post infection detected both peptides, as assessed by indirect ELISA. Lamb peripheral blood mononuclear cells (PBMCs) were exposed to each peptide, as well as to the peptide mixture, and cell proliferation assays were performed at 24, 48 and 72 h. The relative expression of the IL4, IL5, IL6, IL13, CXCL8 and FCεR1A genes was quantified by RTqPCR from lamb PBMCs exposed to the peptide mixture at 24 and 48 h. With respect to immune gene expression, 15- and 3-fold upregulation at 24 h was observed with IL5 and CXCL8, respectively, and 2-fold upregulation of CXCL8 at 48 h. In contrast, downregulation of IL5 was stimulated at 48 h. These data suggest that these peptides (pep-hsp and pep-pcx), which show high identity with intestinal and excretion/secretion serine proteases, can trigger immunogenic activity, and suggest that they may be useful as potential parasite vaccines.

Excreted and secreted products (72/60 kDa) from Haemonchus placei larvae induce in vitro peripheral blood mononuclear cell proliferation and activate the expression of cytokines and FCεR1A receptor.

The aim of the present study was to assess the expression of cytokines and FCεR1A receptor stimulated by Haemonchus placei larval excretory and secretory (ES) products associated with the pathogenesis in calves. Bovine peripheral blood mononuclear cells (PBMC) were stimulated in in vitro assays with H. placei L4 ES product at 8, 12, 16 and 24 h. ES products were collected in in vitro assays at 48 h with molecular weight of 72/60 kDa and isoelectric point of 7.2 pI. Specific IgG for infected and control calves, positive and negative, were employed to recognise H. placei larval ES products by indirect ELISA, showing a mean of 1.8, 0.83 and 0.28 OD, respectively, (p ≤ 0.001). The quantification of relative gene expression was performed using a set of cytokines (IL-2, IFNγ, TGFß, IL-4, IL-5, IL-6, IL-8, IL-10 and IL-13), FCεR1A receptor and housekeeping (GAPDH, ß-actin and ß-2-microglobulin) by RT-qPCR. An early increased expression, 2.2- to 3.4-fold change, of IL-2 (p ≤ 0.001), IL-5 and TGFß (p ≥ 0.05) was determined, followed by TGFß (30.7 and 14.14), IL-8 (102.8 and 1504.4) and IL-10 (60.4 and 1.7) (p ≤ 0.05) after 12 and 16 h, respectively, and reducing the expression level at 24 h. In addition, IL-6, IL-13 and FCεR1A receptor also displayed mild expression level, 2.1 - to 7.60-fold change, at 24 h (p ≥ 0.05). We conclude that ES products of 72/60 kDa collected in vitro from H. placei larvae are recognised by infected hosts and have the ability to induce diverse immune factors to modulate the nematode damage.