Phlebotomus perniciosus Recombinant Salivary Proteins Polarize Murine Macrophages Toward the Anti-Inflammatory Phenotype

Abstract

Phlebotomus perniciosus (Diptera: Phlebotominae) is a medically and veterinary important insect vector. It transmits the unicellular parasite Leishmania infantum that multiplies intracellularly in macrophages causing life-threatening visceral diseases. Leishmania establishment in the vertebrate host is substantially influenced by immunomodulatory properties of vector saliva that are obligatorily co-injected into the feeding site. The repertoire of P. perniciosus salivary molecules has already been revealed and, subsequently, several salivary proteins have been expressed. However, their immunogenic properties have never been studied. In our study, we tested three P. perniciosus recombinant salivary proteins-an apyrase rSP01 and yellow-related proteins rSP03 and rSP03B-and showed their anti-inflammatory nature on the murine bone-marrow derived macrophages. Even in the presence of pro-inflammatory stimuli (IFN-γ and bacterial lipopolysaccharide, LPS), all three recombinant proteins inhibited nitric oxide production. Moreover, rSP03 seems to have a very strong anti-inflammatory effect since it enhanced arginase activity, increased the production of IL-10, and inhibited the production of TNF-α even in macrophages stimulated with IFN-γ and LPS. These results suggest that P. perniciosus apyrase and yellow-related proteins may serve as enhancing factors in sand fly saliva, facilitating the development of Leishmania infection along with their anti-haemostatic properties. Additionally, rSP03 and rSP03B did not elicit the delayed-type hypersensitivity response in mice pre-exposed to P. perniciosus bites (measured as visible skin reaction). The results of our study may help to understand the potential function of recombinant's native counterparts and their role in Leishmania transmission and establishment within the host.

PpSP32, Phlebotomus papatasi immunodominant salivary protein, exerts immunomodulatory effects on human monocytes, macrophages and lymphocytes

“…Downregulation of TNF-α has also been reported for other components of saliva, such adenosine, a pharmacologically active component of P. papatasi saliva [38,39]maxadilan, a salivary component of the sand y Lu. Longipalpis [15] or RsP03 of P. perniciosus [40]. Interestingly, downmodulation of IL-6 production exerted by PpSP32 contrasts with several reports in the literature regarding other salivary sand y components.…”

“…Interestingly, downmodulation of IL-6 production exerted by PpSP32 contrasts with several reports in the literature regarding other salivary sand y components. Accordingly, either maxadilan, P. papatasi, P. alexandri or P. duboscqi salivary extracts have been reported to enhance the production of IL-6 by monocytes or PBMC [15,39,40]. To our knowledge this is the rst report revealing a down regulation of IL-6 by a salivary protein of P. papatasi.…”

PpSP32, the Phlebotomus papatasi immunodominant salivary protein, exerts immunomodulatory effects on human monocytes, macrophages, and lymphocytes

“…Downregulation of TNF-α has also been reported for other components of saliva, such adenosine, a pharmacologically active component of P. papatasi saliva [ 38 , 39 ], maxadilan, a salivary component of the sand fly Lu. longipalpis [ 15 ], or RsP03 of P. perniciosus [ 40 ]. Interestingly, down-modulation of IL-6 production exerted by PpSP32 contrasts with several reports in the literature regarding other salivary sand fly components.…”

“…Interestingly, down-modulation of IL-6 production exerted by PpSP32 contrasts with several reports in the literature regarding other salivary sand fly components. Accordingly, either maxadilan, P. papatasi , P. alexandri , or P. duboscqi salivary extracts have been reported to enhance the production of IL-6 by monocytes or PBMCs [ 15 , 39 , 40 ]. To the best of our knowledge, this is the first report revealing a downregulation of IL-6 by a salivary protein of P. papatasi.…”

Leishmaniasis: Molecular Aspects of Parasite Dimorphic Forms Life Cycle

“…This is due to the fact that it contains potent compounds with vasodilatory and anti-hemostatic properties [42]. Co-inoculation of saliva with parasites has been shown to worsen the disease in several studies, and this is due to the modulatory capacity of the immune response to contribute to parasite survival and replication [43][44][45]. Likewise, PSG has also been shown to contribute to the worsening of the disease, being directly related to the increase in the number of metacyclic promastigote parasites co-inoculated with saliva [27].…”