An Anopheles aquasalis GATA factor Serpent is required for immunity against Plasmodium and bacteria.
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ABSTRACT:
SUBMITTER: Bahia AC
PROVIDER: S-EPMC6171954 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:During Drosophila embryogenesis, a large number of apoptotic cells are efficiently engulfed and degraded by professional phagocytes, macrophages. Phagocytic receptors Six-Microns-Under (SIMU), Draper (Drpr) and Croquemort (Crq) are specifically expressed in embryonic macrophages and required for their phagocytic function. However, how this function is established during development remains unclear. Here we demonstrate that the key regulator of Drosophila embryonic hemocyte differentiation, the transcription factor Serpent (Srp), plays a central role in establishing macrophage phagocytic competence. Srp, a homolog of the mammalian GATA factors, is required and sufficient for the specific expression of SIMU, Drpr and Crq receptors in embryonic macrophages. Moreover, we show that each of these receptors can significantly rescue phagocytosis defects of macrophages in srp mutants, including their distribution in the embryo and engulfment of apoptotic cells. This reveals that the proficiency of macrophages to remove apoptotic cells relies on the expression of SIMU, Crq and/or Drpr. However, Glial Cells Missing (GCM) acting downstream of Srp in the differentiation of hemocytes, is dispensable for their phagocytic function during embryogenesis. Taken together, our study discloses the molecular mechanism underlying the development of macrophages as skilled phagocytes of apoptotic cells.
| S-EPMC5852079 | biostudies-literature
Project description:BackgroundElimination of malaria depends on mastering transmission and understanding the biological basis of Plasmodium infection in the vector. The first mosquito organ to interact with the parasite is the midgut and its transcriptomic characterization during infection can reveal effective antiplasmodial responses able to limit the survival of the parasite. The vector response to Plasmodium vivax is not fully characterized, and its specificities when compared with other malaria parasites can be of fundamental interest for specific control measures.MethodsExperimental infections were performed using a membrane-feeding device. Three groups were used: P. vivax-blood-fed, blood-fed on inactivated gametocytes, and unfed mosquitoes. Twenty-four hours after feeding, the mosquitoes were dissected and the midgut collected for transcriptomic analysis using RNAseq. Nine cDNA libraries were generated and sequenced on an Illumina HiSeq2500. Readings were checked for quality control and analysed using the Trinity platform for de novo transcriptome assembly. Transcript quantification was performed and the transcriptome was functionally annotated. Differential expression gene analysis was carried out. The role of the identified mechanisms was further explored using functional approaches.ResultsForty-nine genes were identified as being differentially expressed with P. vivax infection: 34 were upregulated and 15 were downregulated. Half of the P. vivax-related differentially expressed genes could be related to autophagy; therefore, the effect of the known inhibitor (wortmannin) and activator (spermidine) was tested on the infection outcome. Autophagic activation significantly reduced the intensity and prevalence of infection. This was associated with transcription alterations of the autophagy regulating genes Beclin, DRAM and Apg8.ConclusionsOur data indicate that P. vivax invasion of An. aquasalis midgut epithelium triggers an autophagic response and its activation reduces infection. This suggests a novel mechanism that mosquitoes can use to fight Plasmodium infection.
| S-EPMC6534896 | biostudies-literature
Project description:The mosquito resistance to the insecticides threatens malaria control efforts, potentially becoming a major public health issue. Alternative methods like ivermectin (IVM) administration to humans has been suggested as a possible vector control to reduce Plasmodium transmission. Anopheles aquasalis and Anopheles darlingi are competent vectors for Plasmodium vivax, and they have been responsible for various malaria outbreaks in the coast of Brazil and the Amazon Region of South America.To determine the IVM susceptibility against P. vivax in An. aquasalis and An. darlingi, ivermectin were mixed in P. vivax infected blood: (1) Powdered IVM at four concentrations (0, 5, 10, 20 or 40 ng/mL). (2) Plasma (0 hours, 4 hours, 1 day, 5, 10 and 14 days) was collected from healthy volunteers after to administer a single oral dose of IVM (200 ?g/kg) (3) Mosquitoes infected with P. vivax and after 4 days was provided with IVM plasma collected 4 hours post-treatment (4) P. vivax-infected patients were treated with various combinations of IVM, chloroquine, and primaquine and plasma or whole blood was collected at 4 hours. Seven days after the infective blood meal, mosquitoes were dissected to evaluate oocyst presence. Additionally, the ex vivo effects of IVM against asexual blood-stage P. vivax was evaluated.IVM significantly reduced the prevalence of An. aquasalis that developed oocysts in 10 to 40 ng/mL pIVM concentrations and plasma 4 hours, 1 day and 5 days. In An. darlingi to 4 hours and 1 day. The An. aquasalis mortality was expressively increased in pIVM (40ng/mL) and plasma 4 hours, 1, 5 10 and 14 days post-intake drug and in An. darlingi only to 4 hours and 1 day. The double fed meal with mIVM by the mosquitoes has a considerable impact on the proportion of infected mosquitoes for 7 days post-feeding. The oocyst infection prevalence and intensity were notably reduced when mosquitoes ingested blood from P. vivax patients that ingested IVM+CQ, PQ+CQ and IVM+PQ+CQ. P. vivax asexual development was considerably inhibited by mIVM at four-fold dilutions.In conclusion, whole blood spiked with IVM reduced the infection rate of P. vivax in An. aquasalis and An. darlingi, and increased the mortality of mosquitoes. Plasma from healthy volunteers after IVM administration affect asexual P. vivax development. These findings support that ivermectin may be used to decrease P. vivax transmission.
| S-EPMC5828505 | biostudies-literature
Project description:The mosquito Anopheles gambiae uses its innate immune system to control bacterial and Plasmodium infection of its midgut tissue. The activation of potent IMD pathway-mediated anti-Plasmodium falciparum defenses is dependent on the presence of the midgut microbiota, which activate this defense system upon parasite infection through a peptidoglycan recognition protein, PGRPLC. We employed transcriptomic and reverse genetic analyses to compare the P. falciparum infection-responsive transcriptomes of septic and aseptic mosquitoes and to determine whether bacteria-independent anti-Plasmodium defenses exist. To examine the impact of P. falciparum infection on the mosquito midgut and carcass transcriptomes in the presence or absence of midgut bacteria, we used A. gambiae whole genome microarrays to compare the mRNA abundance of P. falciparum-infected and -naïve mosquitoes of antibiotic- and non-antibiotic treated cohorts. P. falciparum infection induced changes in the abundance of as many as 2,183 and 2,429 transcripts in whole mosquitoes belonging to a variety of functional groups in aseptic and septic mosquitoes. Ultimately, we were interested in identifying the genes involved in bacteria-independent anti-Plasmodium responses, and therefore we focused on transcripts displaying increased abundance in the parasite-infected aseptic midguts, placing a particular emphasis on those with predicted immune functions. Because of the central role of serine protease cascades in regulating insect immune defenses, we focused the remainder of our analysis on a clip-domain serine protease C2 (CLIPC2, AGAP004317) and a serine protease inhibitor 7 (SRPN7, AGAP007693) that were specifically upregulated in the parasite-infected, aseptic mosquito midgut. We showed that SRPN7 negatively and CLIPC2 positively regulate the anti-Plasmodium defense, independently of the midgut-associated bacteria. Co-silencing assays suggested that these two genes may function together in a signaling cascade. Neither gene was regulated, nor modulated, by infection with the rodent malaria parasite Plasmodium berghei, suggesting that SRPN7 and CLIPC2 are components of a defense system with preferential activity towards P. falciparum. Further analysis using RNA interference determined that these genes do not regulate the anti-Plasmodium defense mediated by the IMD pathway, and both factors act as agonists of the endogenous midgut microbiota, further demonstrating the lack of functional relatedness between these genes and the bacteria-dependent activation of the IMD pathway. This is the first study confirming the existence of a bacteria-independent, anti-P. falciparum defense.
2013-08-10 | GSE49690 | GEO
Project description:Malaria affects millions of people worldwide and hundreds of thousands of people each year in Brazil. The mosquito Anopheles aquasalis is an important vector of Plasmodium vivax, the main human malaria parasite in the Americas. Reactive oxygen species (ROS) have been shown to have a role in insect innate immune responses as a potent pathogen-killing agent. We investigated the mechanisms of free radicals modulation after A. aquasalis infection with P. vivax. ROS metabolism was evaluated in the vector by studying expression and activity of three key detoxification enzymes, one catalase and two superoxide dismutases (SOD3A and SOD3B). Also, the involvement of free radicals in the mosquito immunity was measured by silencing the catalase gene followed by infection of A. aquasalis with P. vivax. Catalase, SOD3A and SOD3B expression in whole A. aquasalis were at the same levels of controls at 24 h and upregulated 36 h after ingestion of blood containing P. vivax. However, in the insect isolated midgut, the mRNA for these enzymes was not regulated by P. vivax infection, while catalase activity was reduced 24 h after the infectious meal. RNAi-mediated silencing of catalase reduced enzyme activity in the midgut, resulted in increased P. vivax infection and prevalence, and decreased bacterial load in the mosquito midgut. Our findings suggest that the interactions between A. aquasalis and P. vivax do not follow the model of ROS-induced parasite killing. It appears that P. vivax manipulates the mosquito detoxification system in order to allow its own development. This can be an indirect effect of fewer competitive bacteria present in the mosquito midgut caused by the increase of ROS after catalase silencing. These findings provide novel information on unique aspects of the main malaria parasite in the Americas interaction with one of its natural vectors.
| S-EPMC3575503 | biostudies-literature
Project description:Malaria affects 300 million people worldwide every year and 450,000 in Brazil. In coastal areas of Brazil, the main malaria vector is Anopheles aquasalis, and Plasmodium vivax is responsible for the majority of malaria cases in the Americas. Insects possess a powerful immune system to combat infections. Three pathways control the insect immune response: Toll, IMD, and JAK-STAT. Here we analyze the immune role of the A. aquasalis JAK-STAT pathway after P. vivax infection. Three genes, the transcription factor Signal Transducers and Activators of Transcription (STAT), the regulatory Protein Inhibitors of Activated STAT (PIAS) and the Nitric Oxide Synthase enzyme (NOS) were characterized. Expression of STAT and PIAS was higher in males than females and in eggs and first instar larvae when compared to larvae and pupae. RNA levels for STAT and PIAS increased 24 and 36 hours (h) after P. vivax challenge. NOS transcription increased 36 h post infection (hpi) while this protein was already detected in some midgut epithelial cells 24 hpi. Imunocytochemistry experiments using specific antibodies showed that in non-infected insects STAT and PIAS were found mostly in the fat body, while in infected mosquitoes the proteins were found in other body tissues. The knockdown of STAT by RNAi increased the number of oocysts in the midgut of A. aquasalis. This is the first clear evidence for the involvement of a specific immune pathway in the interaction of the Brazilian malaria vector A. aquasalis with P. vivax, delineating a potential target for the future development of disease controlling strategies.
| S-EPMC3206008 | biostudies-literature
Project description:A causative agent of human malaria, Plasmodium falciparum, is transmitted by Anopheles mosquitoes. The malaria parasite is under intensive attack from the mosquito's innate immune system during its sporogonic development. We have used genetic engineering to create immune-enhanced Anopheles stephensi mosquitoes through blood meal-inducible expression of a transgene encoding the IMD pathway-controlled NF-kB Rel2 transcription factor in the midgut and fat-body tissue. Transgenic mosquitoes showed greater resistance to Plasmodium and microbial infection as a result of timely concerted tissue-specific immune attacks involving multiple effectors. The relatively weak impact of this genetic modification on mosquito fitness under laboratory conditions encourages further investigation of this approach for malaria control.
| S-EPMC3245315 | biostudies-literature
Project description:BACKGROUND:Asymptomatic individuals are one of the major challenges for malaria elimination programs in endemic areas. In the absence of clinical symptoms and with a lower parasite density they constitute silent reservoirs considered important for maintaining transmission of human malaria. Studies from Brazil have shown that infected individuals may carry these parasites for long periods. RESULTS:Patients were selected from three periurban endemic areas of the city of Manaus, in the western Brazilian Amazon. Symptomatic and asymptomatic patients with positive thick blood smear and quantitative real-time PCR (qPCR) positive for Plasmodium vivax were invited to participate in the study. A standardised pvs25 gene amplification by qPCR was used for P. vivax gametocytes detection. Anopheles aquasalis were fed using membrane feeding assays (MFA) containing blood from malaria patients. Parasitemia of 42 symptomatic and 25 asymptomatic individuals was determined by microscopic examination of blood smears and qPCR. Parasitemia density and gametocyte density were assessed as determinants of infection rates and oocysts densities. A strong correlation between gametocyte densities (microscopy and molecular techniques) and mosquito infectivity (P < 0.001) and oocysts median numbers (P < 0.05) was found in both groups. The ability to infect mosquitoes was higher in the symptomatic group (41%), but infectivity in the asymptomatic group was also seen (1.42%). CONCLUSIONS:Although their infectivity to mosquitoes is relatively low, given the high prevalence of P. vivax asymptomatic carriers they are likely to play and important role in malaria transmission in the city of Manaus. The role of asymptomatic infections therefore needs to be considered in future malaria elimination programs in Brazil.
| S-EPMC5935932 | biostudies-literature
Project description:The mosquito Anopheles gambiae uses its innate immune system to control bacterial and Plasmodium infection of its midgut tissue. The activation of potent IMD pathway-mediated anti-Plasmodium falciparum defenses is dependent on the presence of the midgut microbiota, which activate this defense system upon parasite infection through a peptidoglycan recognition protein, PGRPLC. We employed transcriptomic and reverse genetic analyses to compare the P. falciparum infection-responsive transcriptomes of septic and aseptic mosquitoes and to determine whether bacteria-independent anti-Plasmodium defenses exist. Antibiotic treated aseptic mosquitoes mounted molecular immune responses representing a variety of immune functions upon P. falciparum infection. Among other immune factors, our analysis uncovered a serine protease inhibitor (SRPN7) and Clip-domain serine protease (CLIPC2) that were transcriptionally induced in the midgut upon P. falciparum infection, independent of bacteria. We also showed that SRPN7 negatively and CLIPC2 positively regulate the anti-Plasmodium defense, independently of the midgut-associated bacteria. Co-silencing assays suggested that these two genes may function together in a signaling cascade. Neither gene was regulated, nor modulated, by infection with the rodent malaria parasite Plasmodium berghei, suggesting that SRPN7 and CLIPC2 are components of a defense system with preferential activity towards P. falciparum. Further analysis using RNA interference determined that these genes do not regulate the anti-Plasmodium defense mediated by the IMD pathway, and both factors act as agonists of the endogenous midgut microbiota, further demonstrating the lack of functional relatedness between these genes and the bacteria-dependent activation of the IMD pathway. This is the first study confirming the existence of a bacteria-independent, anti-P. falciparum defense. Further exploration of this anti-Plasmodium defense will help clarify determinants of immune specificity in the mosquito, and expose potential gene and/or protein targets for malaria intervention strategies based on targeting the parasite in the mosquito vector.
| S-EPMC3760850 | biostudies-literature
Project description:The mosquito Anopheles gambiae uses its innate immune system to control bacterial and Plasmodium infection of its midgut tissue. The activation of potent IMD pathway-mediated anti-Plasmodium falciparum defenses is dependent on the presence of the midgut microbiota, which activate this defense system upon parasite infection through a peptidoglycan recognition protein, PGRPLC. We employed transcriptomic and reverse genetic analyses to compare the P. falciparum infection-responsive transcriptomes of septic and aseptic mosquitoes and to determine whether bacteria-independent anti-Plasmodium defenses exist. To examine the impact of P. falciparum infection on the mosquito midgut and carcass transcriptomes in the presence or absence of midgut bacteria, we used A. gambiae whole genome microarrays to compare the mRNA abundance of P. falciparum-infected and -naïve mosquitoes of antibiotic- and non-antibiotic treated cohorts. P. falciparum infection induced changes in the abundance of as many as 2,183 and 2,429 transcripts in whole mosquitoes belonging to a variety of functional groups in aseptic and septic mosquitoes. Ultimately, we were interested in identifying the genes involved in bacteria-independent anti-Plasmodium responses, and therefore we focused on transcripts displaying increased abundance in the parasite-infected aseptic midguts, placing a particular emphasis on those with predicted immune functions. Because of the central role of serine protease cascades in regulating insect immune defenses, we focused the remainder of our analysis on a clip-domain serine protease C2 (CLIPC2, AGAP004317) and a serine protease inhibitor 7 (SRPN7, AGAP007693) that were specifically upregulated in the parasite-infected, aseptic mosquito midgut. We showed that SRPN7 negatively and CLIPC2 positively regulate the anti-Plasmodium defense, independently of the midgut-associated bacteria. Co-silencing assays suggested that these two genes may function together in a signaling cascade. Neither gene was regulated, nor modulated, by infection with the rodent malaria parasite Plasmodium berghei, suggesting that SRPN7 and CLIPC2 are components of a defense system with preferential activity towards P. falciparum. Further analysis using RNA interference determined that these genes do not regulate the anti-Plasmodium defense mediated by the IMD pathway, and both factors act as agonists of the endogenous midgut microbiota, further demonstrating the lack of functional relatedness between these genes and the bacteria-dependent activation of the IMD pathway. This is the first study confirming the existence of a bacteria-independent, anti-P. falciparum defense. Aseptic and septic midguts and carcasses from P. falciparum-infected A. gambiae vs aseptic and septic midguts and carcasses from uninfected, blood-fed A. gambiae. 3 biological replicates and 1 pseudo-replicate per each array.
2013-08-10 | E-GEOD-49690 | biostudies-arrayexpress