Early Post-Prandial Regulation of Protein Expression in the Midgut of Chagas Disease Vector Rhodnius prolixus Highlights New Potential Targets for Vector Control Strategy

Abstract

Chagas disease is a vector-borne parasitic disease caused by the flagellated protozoan Trypanosoma cruzi and transmitted to humans by a large group of bloodsucking triatomine bugs. Triatomine insects, such as Rhodnius prolixus, ingest a huge amount of blood in a single meal. Their midgut represents an important interface for triatomine–trypanosome interactions. Furthermore, the development of parasites and their vectorial transmission are closely linked to the blood feeding and digestion; thus, an understanding of their physiology is essential for the development of new strategies to control triatomines. In this study, we used label-free quantitative proteomics to identify and analyze the early effect of blood feeding on protein expression in the midgut of Rhodnius prolixus. We both identified and quantified 124 proteins in the anterior midgut (AM) and 40 in the posterior midgut (PM), which vary significantly 6 h after feeding. The detailed analysis of these proteins revealed their predominant involvement in the primary function of hematophagy, including proteases, proteases inhibitors, amino acids metabolism, primary metabolites processing, and protein folding. Interestingly, our proteomics data show a potential role of the AM in protein digestion. Moreover, proteins related to detoxification processes and innate immunity, which are largely accepted to be triggered by blood ingestion, were mildly modulated. Surprisingly, one third of blood-regulated proteins in the AM have unknown function. This work contributes to the improvement of knowledge on the digestive physiology of triatomines in the early hours post-feeding. It provides key information for selecting new putative targets for the development of triatomine control tools and their potential role in the vector competence, which could be applied to other vector species.

Salivary and Intestinal Transcriptomes Reveal Differential Gene Expression in Starving, Fed and Trypanosoma cruzi-Infected Rhodnius neglectus

“…As suggested by Ribeiro et al, the presence of these molecules in the INT may create a protective network against oxygen reactants that might be produced after hematophagy, as demonstrated for the species R. prolixus (Ribeiro et al, 2014). The increased expression of the Tat gene after hematophagy in R. neglectus (Figure 9A) was also observed in the R. prolixus INT (Ouali et al, 2021). This enzyme participates in the first reaction for the degradation of amino acids and is essential for tyrosine detoxification, an important process for survival in the repast of hematophagous arthropods, such as triatomines (Ribeiro et al, 2014;Sterkel et al, 2016).…”

“…The peptidases identified here have an effect on the intestinal membrane, and their functions in triatomines still need to be better understood (Ribeiro et al, 2014;Ouali et al, 2020;Ouali et al, 2021). Noting that the action of peptidases, in general, is related to the process of protein breakdown, it is expected that the expression of enzymes in this group is still elevated after feeding.…”

“…On the other hand, although rarely described in triatomines, the S10 peptidase R4G841 has already been reported in the anterior and posterior guts of R. prolixus after hematophagy, which presumably participates in digestion and may be related to the activity of carboxypeptidases present in the midgut of triatomines. However, there are caveats for which it was found, whose physiological role still needs to be reviewed (Ouali et al, 2021). We identified an unknown S10 member that is most expressed after hematophagy in the gut of R. neglectus, and its role before the condition also needs to be investigated.…”

“…Some transcripts among the 50 highest expressed in the INT but not among the 50 highest expressed in SG had increased expression in FE and decreased expression in FE + Tc. These include: a Venom cub domain protein 2-like transcript (from P. Plagipennis venom -Walker, 2017) related to developmental processes (Bork and Beckmann, 1993), an antigen-5-like transcript described in SGs from T. brasiliensis (Santos et al, 2007) and R. prolixus (Ribeiro et al, 2004), and transcripts similar to salivary platelet aggregation inhibitors, as was identified for salivary platelet aggregation inhibitor 1 (T1HDI2) in the INT of R. prolixus post-feeding (Ouali et al, 2021); other transcripts, such as those similar to the venom glycin-rich peptide Pp23a, pacifastin, diptericin, and acetyl CoA synthetase, showed lower expression in FE than in FE + Tc at day 2. Among the 50 least expressed transcripts in the INT were transcripts similar to venom polipophorin-like protein 1 and venom peptide Pp26a, both of which showed a more significant decrease in expression on day 9.…”

“…In order to prepare for food receptivity while still fasting, genes involved in diet processing were found to be higher during this period (Figure 9A), highlighting that NADPH P450 reductase is present during metabolism and food detoxification (Scott and Wen, 2001;Feyereisen, 2006;Mamidala et al, 2011); p-Obp is required for the maintenance of intestinal physiology and for nutrient transport (Ribeiro et al, 2014), but its true importance in hematophagy still remains unknown (Ribeiro et al, 2012); an unknown C19 peptidase, a family that deconjugates ubiquitin (Rawlings and Barrett, 1994;Eletr and Wilkinson, 2014) of proteins, which should be protected from higher blood temperatures or should not yet be degraded as they will have some role in digestion (Feder and Hofmann, 1999;Ouali et al, 2020;Ouali et al, 2021); and Hsp70Ba. Heat shock proteins are highly conserved among living organisms, and HSP70 plays an essential role in protein folding and transport, and are present in abundance under conditions of cellular stress (Karlin and Brocchieri, 1998).…”