Hematobin is a novel immunomodulatory protein from the saliva of the horn fly Haematobia irritans that inhibits the inflammatory response in murine macrophages

Abstract

BackgroundThe horn fly Haematobia irritans is a blood-sucking ectoparasite responsible for substantial economic loss of livestock. Like other hematophagous arthropods species, the successful blood-feeding of H. irritans is highly dependent on the modulation of the host’s hemostasis and immune system. Here, we evaluated the biological activity of hematobin (HTB), a protein recently identified in the H. irritans saliva, on macrophage biology. The goal was to understand the putative interactions between the components of H. irritans saliva and the early host immune responses.ResultsThioglycolate-elicited peritoneal macrophages from BALB/c mice were stimulated by lipopolysaccharide (LPS) plus interferon-γ (IFN-γ) in the presence or absence of recombinant HTB. The presence of the salivary protein in the cultures inhibited nitric oxide production and decreased the inducible nitric oxide synthase (iNOS) expression induced by LPS plus IFN-γ. The tumor necrosis factor-α (TNF-α) and interleukin-12p40 (IL-12p40) levels were also reduced in the macrophages pre-incubated with HTB; these findings correlated to the decreased NF-κB expression. The biological activities described here were not associated with changes in annexin V binding to macrophages suggesting that HTB does not induce cell death. In addition, the activity of HTB seems to be specific to macrophages because no changes were observed in lymphocyte proliferation or cytokine production.ConclusionsWe describe here the first bioactive salivary protein of H. irritans. We characterized its ability to modulate macrophage inflammatory response, and the results can help explain how horn flies modulate the host immune system to feed on blood.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3017-z) contains supplementary material, which is available to authorized users.

Antigen-G of Larva Serum of Musca domestica as an Immunoglobulin Production Promoter in Goats under an Organic Maintenance

“…Utilization of salivary fly protein has been studied in overcoming several pathological problems in experimental mammal individuals. The progress of such studies is in line with the report of Breijo et al (2018) indicated that proteins obtained from the substances of horn fly saliva (Haematobia irritans) were able to inhibit the inflammatory in an experiment using mice. The protein which is contained in the body of the Haematobia irritans insect functions as a molecule capable in controlling the insect infestation in livestock as traced by Breijo et al (2017).…”

AeMOPE-1, a Novel Salivary Peptide From Aedes aegypti, Selectively Modulates Activation of Murine Macrophages and Ameliorates Experimental Colitis

“…In addition, the presence of syn-AeMOPE-1 in cultures of resting macrophage did not affect the basal levels of the parameters evaluated. Similarly, macrophage viability was monitored by flow cytometry and by a resazurin-based assay (21,34,44), and no evidence was found concerning AeMOPE-1 toxicity under these conditions. The literature on the activities of Ae.…”

“…Mice were immunized with syn-AeMOPE-1 (20 µg/animal) emulsified in adjuvant as described ( 34 ). Two weeks after the last immunization, mice received an i.v.…”

Aedes aegypti saliva impairs M1-associated proinflammatory phenotype without promoting or affecting M2 polarization of murine macrophages

“…Concomitantly, 25 µl of 0.01% resazurin (prepared in complete medium) were added to all wells. Cell viability was evaluated after 48 h of culture by reading the culture absorbance at 570 and 600 nm in a plate reader and the results are expressed as the difference between those readings as described [20, 29, 30].…”