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Background: It is assumed that robotic-assisted surgery (RAS) may facilitate complex pelvic dissection for rectal cancer compared to the laparoscopic-assisted resection (LAR). The aim of this study was to compare perioperative morbidity, short- and long-term oncologic, and functional outcomes between the RAS and LAR approaches. Methods: Between 2015 and 2021, all rectal cancers operated on by (LAR) or (RAS) were retrospectively reviewed in two colorectal surgery centers. Results: A total of 197 patients were included in the study, with 70% in the LAR group and 30% in the RAS group. The tumor location and stage were identical in both groups (not significant = NS). The overall postoperative mortality rate was not significantly different between the two groups. (0% LAR; 0.5% RAS; NS). The postoperative morbidity was similar between the two groups (60% LAR vs 57% RAS; NS). The number of early surgical re-interventions within the first 30 days was similar (10% for the LAR group and 3% for the RAS group; NS). The rate of complete TME was similar (88% for the LAR group and 94% for the RAS group; NS). However, the rate of circumferential R1 was significantly higher in the LAR group (13%) compared to the RAS group (2%) (p= 0.009). The 3-year recurrence rate did not differ between the two groups (77% for both groups; NS). After a mean follow-up of three years, the incidence of anterior resection syndrome was significantly lower in the LAR group compared to the RAS group (54 vs 76%; p= 0.030). Conclusions: The use of a RAS was found to be reliable for oncologic outcomes and morbidity. However, the expected benefits for functional outcomes were not observed. Therefore, the added value of RAS for rectal cancer needs to be reassessed in light of new laparoscopic technologies and patient management options.

Les fistules urétro-rectales (FUR) constituent une pathologie rare mais grave dont le traitement est mal codifié. Cette étude a pour but d’évaluer les résultats à court et à long terme d’une prise en charge multidisciplinaire.

Cancer cachexia is a multifactorial syndrome characterized by involuntary and pathological weight loss, mainly due to skeletal muscle wasting, resulting in a decrease in patients' quality of life, response to cancer treatments, and survival. Our objective was to investigate skeletal muscle alterations in cachectic cancer patients. This is a prospective study of patients managed for pancreatic or colorectal cancer with an indication for systemic chemotherapy (METERMUCADIG ‐ NCT02573974). One lumbar CT image was used to determine body composition. Patients were divided into three groups [8 noncachectic (NC), 18 with mild cachexia (MC), and 19 with severe cachexia (SC)] based on the severity of weight loss and muscle mass. For each patient, a pectoralis majormuscle biopsy was collected at the time of implantable chamber placement. We used high‐resolution oxygraphy to measure mitochondrial muscle oxygen consumption on permeabilized muscle fibres. We also performed optical and electron microscopy analyses, as well as gene and protein expression analyses. Forty‐five patients were included. Patients were 67% male, aged 67 years (interquartile range, 59–77). Twenty‐three (51%) and 22 (49%) patients were managed for pancreatic and colorectal cancer, respectively. Our results show a positive correlation between median myofibres area and skeletal muscle index (P =0.0007). Cancer cachexia was associated with a decrease in MAFbx protein expression (P <0.01), a marker of proteolysis through the ubiquitin‐proteasome pathway. Mitochondrial oxygen consumption related to energy wasting was significantly increased (SC vs. NC, P =0.028) and mitochondrial area tended to increase (SC vs. MC, P =0.056) in SC patients. On the contrary, mitochondria content and networks remain unaltered in cachectic cancer patients. Finally, our results show no dysfunction in lipid storage and endoplasmic reticulum homeostasis. This clinical protocol brings unique data that provide new insight to mechanisms underlying muscle wasting in cancer cachexia. We report for the first time an increase in mitochondrial energy wasting in the skeletal muscle of severe cachectic cancer patients. Additional clinical studies are essential to further the exploring and understanding of these alterations.

While the treatment of locally advanced lower and middle rectal cancer with total mesorectal excision (TME) after neoadjuvant therapy is now well defined, the treatment of locally advanced upper rectal cancer (LAURC) remains controversial. Although most teams and academic societies recommend upfront surgery (US) with partial mesorectal excision (PME), as this appears to be sufficient for these tumors, the literature remains conflicting regarding the additional use of neoadjuvant therapy and TME. Current recommendations for the treatment of LAURC do not reflect actual clinical practice. Notably, there is a paucity of published data specific to the treatment of LAURC since most of the data are from sub-analyses of different cohorts. Another important point responsible for the inconsistent data situation is the fact that the current definition of upper rectal cancer is based on anatomical criteria that are difficult to reproduce and therefore also differ between international professional societies.

La prise en charge des cancers du bas rectum est un enjeu thérapeutique à la fois sur le plan oncologique et fonctionnel. Cette étude analyse les résultats oncologiques et la morbidité postopératoire après exérèse totale du mésorectum par voie transanale endoscopique (TaTME) pour les tumeurs du bas rectum.

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Lymph node recurrences (LNR) from colorectal cancer (CRC) still represent a therapeutic challenge, as standardized recommendations have yet to be established. The aim of this study was to analyze short- and long-term oncological outcomes following resection of LNR from CRC.

To evaluate the short and long-term results of in situ prosthetic graft treatment using rifampicin-soaked silver polyester graft in patients with aortic infection.

La chirurgie du cancer du côlon gauche en occlusion (CCGO) est controversée. L’objectif est de rapporter les résultats postopératoires et oncologiques des différentes options chirurgicales pour un CCGO.

Designing multitarget drugs have raised considerable interest due to their advantages in the treatment of complex diseases such as cancer. Their design constitutes a challenge in antitumor drug discovery. The present study reports a dual inhibition of tubulin polymerization and HDAC activity. On the basis of 1,1-diarylethylenes (isoCA-4) and belinostat, a series of hybrid molecules was successfully designed and synthesized. In particular compounds, 5fand 5hwere proven to be potent inhibitors of both tubulin polymerization and HDAC8 leading to excellent antiproliferative activity.

Preclinical models based on patient-derived xenografts have remarkable specificity in distinguishing transformed human tumor cells from non-transformed murine stromal cells computationally. We obtained 29 pancreatic ductal adenocarcinoma (PDAC) xenografts from either resectable or non-resectable patients (surgery and endoscopic ultrasound-guided fine-needle aspirate, respectively). Extensive multiomic profiling revealed two subtypes with distinct clinical outcomes. These subtypes uncovered specific alterations in DNA methylation and transcription as well as in signaling pathways involved in tumor-stromal cross-talk. The analysis of these pathways indicates therapeutic opportunities for targeting both compartments and their interactions. In particular, we show that inhibiting NPC1L1 with Ezetimibe, a clinically available drug, might be an efficient approach for treating pancreatic cancers. These findings uncover the complex and diverse interplay between PDAC tumors and the stroma and demonstrate the pivotal role of xenografts for drug discovery and relevance to PDAC.

Although primary tumor sidedness (PTS) has a known prognostic role in sporadic colorectal cancer (CRC), its role in Inflammatory Bowel Disease related CRC (IBD-CRC) is largely unknown. Thus, we aimed to evaluate the prognostic role of PTS in patients with IBD-CRC.

The parasitic protozoa Trypanosoma cruzi and Leishmania sp release a variety of molecules into their mammalian hosts (ESA: excretory-secretory products). The effects of these ESA on the host cell function may participate in the establishment of a successful infection, in which the parasite persists for a sufficient period of time to complete its life cycle. A number of regulatory components or processes originating from the parasite that control or regulate the metabolism and the growth of host cell have been identified. The purpose of the present review is to analyze some of the current data related to the parasite ESA that interfere with the host cell physiology. Special attention is given to members of conserved protein families demonstrating remarkable diversity and plasticity of function (ie, glutathione S-transferases and related molecules; members of the trans-sialidase and mucin family; and members of the ribosomal protein family). The identification of parasite target molecules and the elucidation of their mode of action toward the host cell represents a step forward in efforts aimed at an immunotherapeutic or pharmacological control of parasitic infection.

La chimiothérapie nébulisée par voie intra péritonéale (PIPAC) a été proposée pour traiter les métastases péritonéales de l’adénocarcinome gastrique (GCPM).

Les fistules urétro-rectales (FUR) constituent une pathologie rare mais grave dont le traitement est mal codifié. Cette étude a pour but d’évaluer les résultats à court et à long terme d’une prise en charge multidisciplinaire.

Le but de cette étude était d’évaluer les résultats de la PIPAC chez des patients ayant une carcinose péritonéale non résécable d’origine colorectale (CPCR).

A major impediment to the effective treatment of patients with pancreatic ductal adenocarcinoma (PDAC) is the molecular heterogeneity of this disease, which is reflected in an equally diverse pattern of clinical outcome and in responses to therapies. We developed an efficient strategy in which PDAC samples from 17 consecutive patients were collected by endoscopic ultrasound–guided fine-needle aspiration or surgery and were preserved as breathing tumors by xenografting and as a primary culture of epithelial cells. Transcriptomic analysis was performed from breathing tumors by an Affymetrix approach. We observed significant heterogeneity in the RNA expression profile of tumors. However, the bioinformatic analysis of these data was able to discriminate between patients with long- and short-term survival corresponding to patients with moderately or poorly differentiated PDAC tumors, respectively. Primary culture of cells allowed us to analyze their relative sensitivity to anticancer drugs in vitrousing a chemogram, similar to the antibiogram for microorganisms, establishing an individual profile of drug sensitivity. As expected, the response was patient dependent. We also found that transcriptomic analysis predicts the sensitivity of cells to the five anticancer drugs most frequently used to treat patients with PDAC. In conclusion, using this approach, we found that transcriptomic analysis could predict the sensitivity to anticancer drugs and the clinical outcome of patients with PDAC.

Ampullary carcinoma is a rare tumor. There are neither sufficient available data related to management after resection of the neoplasm of the ampulla of Vater, nor any international recommendations. The aim of this study was to identify factors associated with recurrence and survival after curative resection.

Understanding the complex interactions between Leishmaniaand dendritic cells (DCs) is central to the modulation of the outcome of this infection, given that an effective immune response against Leishmaniais dependent on the successful activation and maturation of DCs. We report here that Leishmania infantumpromastigotes successfully infect mouse bone marrow-derived DCs without triggering maturation, as shown by a failure in the up-regulation of CD40 and CD86 expression, and that parasites strongly counteract the lipopolysaccharide-triggered maturation of DCs. A small increase in interleukin (IL)-12 and IL-10 transcription and secretion and a decrease in IL-6 were observed in infected cells. This arrested DC maturation state is actively promoted by parasites because heat-killed or fixed parasites increased cytokine and costimulatory molecule expression. At a molecular level, L. infantumrapidly induced activation of phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2, whereas no effect was observed in the c-Jun N-terminal kinase and p38 mitogen-activated protein kinase proinflammatory pathways. Moreover, parasites actively promoted cleavage of the nuclear factor-κB p65RelAsubunit, causing its impairment. The blockade of phosphatidylinositol 3-kinase/Akt by either treatment of bone marrow-derived DCs with wortmannin or transfection with an Akt dominant-negative mutant resulted in a strong decrease in infection rates, revealing for the first time a crucial role of this pathway on Leishmaniaengulfment by DCs. Overall, our data indicate that activation of Akt and impairment of nuclear factor-κB are responsible for immunogenicity subversion of L. infantum-infected DCs.

Leishmaniasis is a parasitic infection that affects millions of people worldwide, especially in tropical and subtropical areas, and is responsible for high mortality and morbidity. The therapies available up to the present are far from satisfactory and, since leishmaniasis affects poor people in poor regions, the development of new drugs has been neglected due to the lack of commercial motivation. Safe and orally available drugs, especially against the visceral form of the disease, are needed. An overview of the main strategies for antileishmanial drug development, mainly focused on the target-based drug development approach, is given.

Purpose: Multiple biochemical and molecular alterations occur in pancreatic cancer cells. In the present study, attempts were made for the first time, to explore the level of expression of members of histone deacetylase encoding genes (HDACs) in four pancreatic tumor cell lines: Panc-1, BxPC-3, SOJ-6 and MiaPaCa-2; and two non-related tumor cells: Jurkat and HeLa. Furthermore, we examined the possible relationship between the levels of HDACs expression and the sensitivity/resistance to HDAC inhibitors (TSA, Nicotinamide and Sirtinol). Methods: We have used four human pancreatic tumor cell lines and two-non related tumor cells, to evaluate the expression of HDAC encoding genes by RT-PCR and Western blot analysis. We also measured the effect of certain HDAC inhibitors (HDIs) on cell growth, cell cycle alteration, membrane phosphatidyl-serine exposure, DNA fragmentation, and mitochondrial membrane potential loss.Results: We have found that although a slight variation in the profiles of gene expression among cell lines could be evidenced, HDACs protein synthesis seem to be similar. Furthermore, the cells were equally sensitive to inhibition by Sirtinol whereas some variation in the IC50 could be seen in the case of TSA. We also demonstrate that the drugs had the capacity to induce the death of cells by apoptosis. Conclusions: Taken together, our data support the notion that the level of cell sensitivity to the HDIs might be related to the level of expression of genes such as those encoding proteins playing a role in cell cycle checkpoints control but not HDAC per se.

Abstract: During the past few years, the silent information regulator SIR2 protein family has attracted great interest due to its implication in an organism’s life span extension. They bear diverse subcellular localization and play a role in transcriptional silencing and DNA repair. The biochemical reaction catalysed by these enzymes (nicotinamide adenine dinucleotide–dependant deacetylase/adenosine diphosphate–ribosyl transferase) is supposed to be linked to metabolism. Members of this protein family were described in parasitic organisms, but little information is available on potential functions of such enzymes in these organisms. In this article, we review recent information on structure and peculiar functions of SIR2s in eukaryotes, with emphasis on parasitic protozoa, particularly the Trypanosomatidae. Through the enzyme localization and the diverse substrates and by-products of the enzymatic reactions, we approach the potential pathways in which the Leishmania cytosolic SIR2 protein can be involved.

Immunopathology of Chagas' disease in Balb/c mice infected with 2 Trypanosoma cruzi clones, belonging to the T. cruzi I lineage and presenting different in vitro virulence (P/209 cl1>SO34 cl4) was compared. In the acute phase, evading mechanisms such as parasite-induced lymphocyte polyclonal activation and T cell immunosuppression were higher in mice infected with the clone giving a higher parasitaemia (P/209 cl1). A similar increase of non-specific isotypes was observed in both infections with IgG2a prevalence. Interestingly, CD8+ cell hypercellularity and lymphocyte immunosuppression were observed during the chronic phase (245 days post-infection) in mice infected by the most virulent clone. In the same way, the parasite-specific antibody response was more intense in P/209 cl1-infected mice over the acute phase. During the chronic phase this response remarkably dropped down in SO34 cl4-infected mice exclusively. Finally, P/209 cl1-infected mice presented a more severe inflammation and tissue damage in heart and quadriceps than SO34 cl4-infected mice. This comparative study showed differences between the two clones: a higher virulence in vivo being clearly associated with a greater ability to induce evasion mechanisms and severe tissue damage.

In control programs for vectorial transmission of Chagas’ disease, conventional microscopic procedures are generally performed to determine baseline levels of infectivity of vectors. Reported here are data using Polymerase Chain Reaction in the detection of Trypanosoma cruziin Triatoma dimidiata, one of the principal vectors of Chagas’ disease in Ecuador. The microscopy and PCR techniques showed a high percentage of vector infection in Pedro Carbo, province of Guayas (Ecuador), with 44.16 % and 46.13 % positive insects, respectively. This contrasted with the very low Chagas seropositivity recorded (0.5 %). Since T. dimidiatawas the only vector of the Chagas’ disease found in Pedro Carbo and looking at the vector behavior, our data suggest that despite the high T. dimidiatainfection, the low Chagas seropositivity detected is closely associated with the epidemiological and ecological context of T. dimidiatain Pedro Carbo.

ABSTRACTOur study represents the first report demonstrating the antileishmanial activity of nicotinamide (NAm), a form of vitamin B3. A 5 mM concentration of NAm significantly inhibited the intracellular growth of Leishmaniaamastigotes and the NAD-dependent deacetylase activity carried by parasites overexpressing Leishmania majorSIR2 (LmSIR2). However, the transgenic parasites were as susceptible as the wild-type parasites to NAm-induced cell growth arrest. Therefore, we conclude that NAm inhibits leishmanial growth and that overexpression of LmSIR2 does not overcome this inhibition. The mechanism of the inhibition is not defined but may include other in vivo targets. NAm may thus represent a new antileishmanial agent which could potentially be used in combination with other drugs during therapy.

ABSTRACTWe have recently characterized a novel Leishmania majorgene encoding a polypeptide of 30 kDa that was homologous to mammalian ribosomal protein S3a and was named LmS3a-related protein (LmS3arp). The protein was found to be expressed by all the Leishmaniaspecies so far examined (L. infantum, L. amazonensis, andL. mexicana). In the present study we have extended our approach to the analysis of LmS3arp activity on T- and B-cell functions in a murine model. The results presented in this report show that LmS3arp plays a dual role in the regulation of T- and B-cell reactivity. Indeed, we found that injection of the LmS3arp recombinant protein (rLmS3arp) into BALB/c mice induces preferential activation of B cells, as shown by the following criteria: (i) increased expression of CD69 molecules on immunoglobulin M (IgM)-secreting spleen cells, (ii) a considerable increase of IgM-secreting B cells, and (iii) elevated levels of IgM antibodies in the sera of injected animals. Moreover, the IgM antibodies are not specific to theLeishmaniaantigens but preferentially recognize heterologous antigens like myosin, thyroglobulin, DNA, and keyhole limpet hemocyanin. Furthermore, the strong polyclonal expansion of nonspecific, non-parasite-directed B-cell clones induced by rLmS3arp is concomitant with a marked inhibition of T-cell proliferation. Analysis of cytokine production revealed a significant downregulation of gamma interferon, interleukin-2 (IL-2), and IL-12 secretion. Taken together, our data suggest that rLmS3arp, through direct or indirect action toward B and T cells and cytokine secretion, could participate in the immunoregulatory processes that play a role in the balance of the Th1 and Th2 immune response.

ABSTRACTThe basic treatment of leishmaniasis consists in the administration of pentavalent antimonials. The mechanisms that contribute to pentavalent antimonial toxicity against the intracellular stage of the parasite (i.e., amastigote) are still unknown. In this study, the combined use of several techniques including DNA fragmentation assay and in situ and cytofluorometry terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling methods and YOPRO-1 staining allowed us to demonstrate that potassium antimonyl tartrate, an Sb(III)-containing drug, was able to induce cell death associated with DNA fragmentation in axenic amastigotes ofLeishmania infantumat low concentrations (10 μg/ml). This observation was in close correlation with the toxicity of Sb(III) species against axenic amastigotes (50% inhibitory concentration of 4.75 μg/ml). Despite some similarities to apoptosis, nuclease activation was not a consequence of caspase-1, caspase-3, calpain, cysteine protease, or proteasome activation. Altogether, our results demonstrate that the antileishmanial toxicity of Sb(III) antimonials is associated with parasite oligonucleosomal DNA fragmentation, indicative of the occurrence of late events in the overall process of apoptosis. The elucidation of the biochemical pathways leading to cell death could allow the isolation of new therapeutic targets.

An intense suppression of T cell proliferation to mitogens and to antigens is observed in a large number of parasitic infections. The impairment of T cell proliferation also occurred during the acute phase of Chagas′ disease, caused by the intracellular protozoan parasite Trypanosoma cruzi . A wealth of evidence has accumulated that illustrates the ability of T. cruzi released molecules to influence directly a variety of diverse immunological functions. In this paper, we review the data concerning the immunoregulatory effects of T. cruzi Tc24 (a B cell activator antigen) and Tc52 (an immunosuppressive protein) released molecules on the host immune system. The gene targeting approach developed to further explore the biological function(s) of Tc52 molecule, revealed interesting unexpected functional properties. Indeed, in addition to its immunusuppressive activity a direct or indirect involvement of Tc52 gene product alone or in combination with other cellular components in T. cruzi differentiation control mechanisms have been evidenced. Moreover, targeted Tc52 replacement allowed the obtention of parasite mutants exhibiting low virulence in vitro and in vivo . Thus, the generation of a complete deficiency state of virulence factors by gene targeting should provide a means to assess the importance of these factors in the pathophysiological processes and disease progression. It is hoped that such approaches might allow rational design of tools to control T. cruzi infections.

Il n’existe pas de recommandation concernant l’intervention à réaliser en cas de tumeur de l’angle colique gauche (TACG) en occlusion. Quatre procédures se discutent : stomie de proche amont (SA), colectomie angulaire gauche (CAG), hémicolectomie gauche (HG) vraie et colectomie subtotale (CST). Le but de cette étude multicentrique était de comparer les résultats périopératoires, histologiques et de survie de ces interventions.

ABSTRACTThe mechanism(s) of activity of pentavalent antimony [Sb(V)] is poorly understood. In a recent study, we have shown that potassium antimonyl tartrate, a trivalent antimonial [Sb(III)], was substantially more potent than Sb(V) against both promastigotes and axenically grown amastigotes of three Leishmaniaspecies, supporting the idea of an in vivo metabolic conversion of Sb(V) into Sb(III). We report that amastigotes of Leishmania infantumcultured under axenic conditions were poorly susceptible to meglumine [Glucantime; an Sb(V)], unlike those growing inside THP-1 cells (50% inhibitory concentrations [IC50s], about 1.8 mg/ml and 22 μg/ml, respectively). In order to define more precisely the mode of action of Sb(V) agents in vivo, we first induced in vitro Sb(III) resistance by direct drug pressure on axenically grown amastigotes ofL. infantum. Then we determined the susceptibilities of both extracellular and intracellular chemoresistant amastigotes to the Sb(V)-containing drugs meglumine and sodium stibogluconate plusm-chlorocresol (Pentostam). The chemoresistant amastigotes LdiR2, LdiR10, and LdiR20 were 14, 26, and 32 times more resistant to Sb(III), respectively, than the wild-type one (LdiWT). In accordance with the hypothesis described above, we found that intracellular chemoresistant amastigotes were resistant to meglumine [Sb(V)] in proportion to the initial level of Sb(III)-induced resistance. By contrast, Sb(III)-resistant cells were very susceptible to sodium stibogluconate. This lack of cross-resistance is probably due to the presence in this reagent of m-chlorocresol, which we found to be more toxic than Sb(III) to L. infantumamastigotes (IC50s, of 0.54 and 1.32 μg/ml, respectively). Collectively, these results were consistent with the hypothesis of an intramacrophagic metabolic conversion of Sb(V) into trivalent compounds, which in turn became readily toxic to theLeishmaniaamastigote stage.

Macrophage-Trypanosoma cruzi interactions were studied by using a newly generated macrophage hybridoma cell line (2C11-12) that was selected for its capacity to produce high levels of reactive oxygen intermediates. This cell line was found to be a suitable host cell for T. cruzi, and intracellular parasitic development could be inhibited by activation with gamma interferon. When exposed to opsonized Trypanosoma brucei, Micrococcus lysodeikticus, or Legionella pneumophila, the activated macrophage cell line produces a high chemiluminescent signal, indicating the release of reactive oxygen intermediates. Alternatively, when opsonized T. cruzi was added to these activated macrophages, this parasite failed to stimulate a chemiluminescent response, suggesting an impairment in the triggering of the respiratory burst.

Although trypanothione [T(S)2] is the major thiol component in trypanosomatidae, significant amounts of glutathione are present in Trypanosoma cruzi. This could be explained by the existence of enzymes using glutathione or both glutathione and T(S)2 as cofactors. To assess these hypotheses, a cytosolic fraction of T. cruzi epimastigotes was subjected to affinity chromatography columns using as ligands either S-hexylglutathione or a non-reducible analogue of trypanothione disulphide. A similar protein of 52 kDa was eluted in both cases. Its partial amino acid sequence indicated that it was identical with the protein encoded by the TcAc2 cDNA previously described [Schoneck, Plumas-Marty, Taibi et al. (1994) Biol. Cell 80, 1-10]. This protein showed no significant glutathione transferase activity but surprisingly catalysed the thiol-disulphide exchange between dihydrotrypanothione and glutathione disulphide. The kinetic parameters were in the same range as those determined for trypanothione reductase toward its natural substrate. This trypanothione-glutathione thioltransferase provides a new target for a specific chemotherapy against Chagas' disease and may constitute a link between the glutathione-based metabolism of the host and the trypanothione-based metabolism of the parasite.

The levels of fibronectin (FN), a multifunctional glycoprotein known to mediate in vitro Trypanosoma cruzi-host cell adhesion, were measured in the plasma of T. cruzi-infected BALB/c mice. The infection induced a long-lasting increase of fibronectin levels during the acute parasitemic phase of the disease. Immunoblotting analysis showed the occurrence of lower-molecular-size FN fragments in the plasma of acutely infected animals, suggesting an infection-related FN degradation. FN levels were found to be significantly lower in dying mice harboring higher parasitemias than in surviving animals. A weak level of natural IgM against the RGD adhesion site of FN was detected before and during the first 3 weeks of infection. The level was significantly higher in surviving mice. From the fourth week postinfection, a significant increase in the levels of anti-RGD antibodies coincided with a decrease of circulating FN. These antibodies were mainly of the IgM, IgG1, and IgG2a isotypes. Taken together, these data suggest that both FN and anti-FN antibodies may contribute to the outcome of T. cruziinfection in mice.

Some in vitro and in vivo biological activities of an octadecapeptide derived from an 85-kDa surface protein of Trypanosoma cruzi trypomastigote were studied. The peptide coupled to a carrier protein induced the proliferative response of lymph node cells from mice immunized with various antigens. Moreover, sera from mice immunized with the coupled peptide were found to contain antibodies against a number of self and nonself antigens: fibronectin, bovine serum albumin, myosin, tetanus toxoid, ovalbumin, keyhole limpet hemocyanin, and DNA. These results are discussed in the context of Chagas' disease immunopathology.

A 24-kDa recombinant protein from Trypanosoma cruzi (rTc24) was evaluated by enzyme-linked immunosorbent assay (ELISA) and Western blot (immunoblot) tests to identify treated chagasic patients considered parasitologically cured on the basis of persistently negative tests of hemocultures and lytic antibodies. Some of these patients were termed dissociated because their sera, although negative by the complement-mediated lysis test, were positive by conventional serology. The negative lysis test indicates the absence of active infection after specific treatment, but this assay requires live and infectious parasites and cannot be used easily in a laboratory routine. Here we tested rTc24 by ELISA and Western blotting as an alternative for the complement-mediated lysis test. For the group of patients with active infection despite the treatment (uncured patients), all the sera tested recognized rTc24 in both tests. For the dissociated patients, approximately 80% of the sera did not react with rTc24 in the ELISA or in Western blots, in agreement with the negative complement-mediated lysis tests. Thus, the 24-kDa T. cruzi recombinant antigen, when used for initial trials to evaluate cure of chagasic patients submitted to specific treatment, will allow the identification of most, but not all, cases.

We have previously isolated and characterized a Trypanosoma cruzi cDNA encoding a polypeptide with a molecular mass of 52 kDa (Tc52) sharing significant homology to glutathione S-transferase. In the present study, by molecular and immunological approaches, we showed that Tc52 is preferentially expressed by dividing forms of the parasite: (e.g., epimatigotes and amastigotes). Moreover, we could identify the reactive antigen in different T. cruzi strains. A different pattern of reactivity on immunoblots was observed in the case of Trypanosoma rangeli. Furthermore, immunofluorescence assays using T. cruzi epimastigote culture forms revealed that the reactive antigen is localized within cytoplasmic organelles morphologically ressembling the structures pre viously designated as the reservosome found mostly at the posterior end of the parasite. Furthermore, the antibodies did not react against trypomastigotes which emerged from infected Fibroblasts, whereas amastigotes showed polar fluorescence. Immunogold labeling and electron micrographs further revealed that the Tc52 protein is mainly associated with organelles composed of a large network of multivesicular structures, the latter being more abundant in epimastigotes. Taken together, these results demonstrated that Tc52 is associated with organelles composed of a multivesicular network and appears to be developmentally regulated, being fully expressed by parasite dividing forms.Copyright 1995, 1999 Academic Press, Inc.