Innate trypanolytic factors in triatomine hemolymph against Trypanosoma rangeli and T. cruzi: a comparative study in eight Chagas disease vectors

Abstract

There is limited information about the innate immunity of triatomines against Trypanosoma rangeli, an infectious, non-pathogenic human parasite, and T. cruzi, the causative agent of Chagas’ disease. This study aimed at addressing this gap by studying the in vitro trypanolytic hemolymph activity from insects not infected by T. rangeli or T. cruzi. Eight triatomine species were examined including Rhodnius prolixus, R. robustus, R. colombiensis, R. pallescens, R. pictipes, Triatoma dimidiata, T. maculata, and Panstrongylus geniculatus. The hemolymph of R. prolixus and R. robustus laboratory colonies demonstrated strong trypanolytic activity during the first 14 hours of parasite incubation with 81% lysis for the T. rangeli C genotype, 90% for the E genotype, 95% for T. cruzi discrete taxonomic unit (DTU) TcII, 94% for TcV, 96% for TcVI, 94% for Tcbat, and 90% for Tcmarinkellei. No lysis activity was detected 14 or 24 hours after parasite incubation with the hemolymph of insects from R. pictipes R. pallescens, P. geniculatus, and T. maculata colonies. Identical results (absence of lysis) were observed using hemolymph from R. colombiensis and T. dimidiata laboratory colonies and specimens captured in sylvatic environments. The hemolymph lytic activity against recently obtained cultures (95% decrease in live parasite count) and long-term T. cruzi TcII ones (96% decrease) was similar. Lytic activity was similar in hemolymph from R. prolixus nymphs, males and females and insects fed on chicken or mouse blood. This is the first comparative study of the trypanolytic activity of hemolymph from different triatomine species against T. rangeli and T. cruzi genotypes. Although the chemical structures of such lysis factors and the mechanisms determining their expression have not been fully determined, their identification furthers our understanding of triatomines’ innate immunity and their role in Trypanosoma transmission.

Metaciclogénesis de Trypanosoma cruzi en Belminus ferroae (Reduviidae: Triatominae) y capacidad infectiva de las heces en condiciones de laboratorio

“…En futuros estudios, sería interesante evaluar el papel de los agentes tripanolíticos presentes en la hemolinfa de los artrópodos que le sirven de huésped a B. ferroae . Ello porque, por ejemplo, recientemente se ha detectado in vitro la actividad anti- T. cruzi y anti- T. rangeli en varias especies de triatominos de importancia sanitaria ( 19 ). Por otra parte, en especies de blatodeos, como Blaberus discoidalis o Periplaneta americana , se han aislado péptidos o lectinas con actividad antibacteriana (por ejemplo, Escherichia coli ) ( 21 ) que podrían exhibir actividad anti- T. cruzi .…”

“…El recuento de tripomastigotes ¿sanguícolas? se hizo en 100 campos microscópicos con 400X ¿( 19 )? ¿Debería ser la 19?…”

Antimicrobial Peptides (AMPs): Potential Therapeutic Strategy against Trypanosomiases?

“…In trypanosomes such as Trypanosoma evansi and Trypanosoma equiperdum , causing surra and dourine in animals, some AMPs have been shown to exert an trypanocidal effect; hence, they have been proposed for use in new treatment strategies of trypanosomiasis in animals [ 150 , 151 ]. Furthermore, AMPs isolated from triatomine hemolymph have been shown to have trypanolytic activity against different strains of Trypanosoma rangeli , an infectious but non-pathogenic human parasite [ 152 ]. In these trypanosomes, AMPs exert their action through different mechanisms, including plasma membrane permeabilization, mitochondrial alteration, and parasite lysis [ 150 , 151 , 152 ].…”

“…Furthermore, AMPs isolated from triatomine hemolymph have been shown to have trypanolytic activity against different strains of Trypanosoma rangeli , an infectious but non-pathogenic human parasite [ 152 ]. In these trypanosomes, AMPs exert their action through different mechanisms, including plasma membrane permeabilization, mitochondrial alteration, and parasite lysis [ 150 , 151 , 152 ].…”

“…Trypanolytic factors with activity against T. cruzi from different discrete taxonomic units (DTU): TcII, TcV, TcVI Tcba, and Tcmarinkellei have also been identified in the hemolymph of the triatomines Rhodnius prolixus and Rhodnius robustus . The lytic activity of these factors is independent of the developmental stage and sex of the vector, and the blood source [ 152 ]. Although the chemical structures and mechanism of action of these lytic factors are unknown, it has been shown that these factors or their precursors were proteins or AMPs [ 189 ].…”