Key issues for implementation of Genomics in Healthcare: a Policy Brief

Issue/problem

Healthcare (HC) can significantly benefit from genomic information for earlier, accurate diagnosis, effective personalized treatment with less adverse events, and accurate profiling of individuals for disease prevention. However, European countries are currently at variable maturity stages regarding the implementation of genomic medicine (GM) in healthcare, hindering the equitable delivery of personalized medicine to citizens across borders.

Description of the problem

The European 1+Million Genomes Initiative (1+MG) aims to provide cross-border access to quality genomic information and related clinical data, to advance data-driven research and HC solutions to benefit citizens. This initiative is encouraging countries to develop national GM strategies, but guidance for successful implementation is needed. In this context, the Beyond 1 Million Genomes, a supporting action to the 1+MG initiative, organized three Country Exchange Visits (CEV) to discuss critical issues, share experiences and best practices, for the implementation of sustainable GM strategies in healthcare.

Results

The United Kingdom, Estonia and Finland, which have advanced GM programs, hosted CEV describing progress and lessons learnt. Representatives of 1+MG signatory countries participated in these events and were able to present country level progress. The resulting Policy Brief (PB) captures key issues discussed at the CEVs, with real-life examples, and proposes policy recommendations for the successful implementation of GM in European healthcare systems.

Lessons

Sustainable GM implementation in HC systems requires: 1) Patient and citizens trust and engagement; 2) Sustainable infrastructure and data regulation, with solid ethical and legal frameworks; 3) Capacity building of healthcare professionals; 4) A strong ecosystem involving all stakeholders, and encouraging synergies between healthcare, research and industry to promote continuous innovation.

Key messages

• The implementation of GM in healthcare will take countries further towards making personalized medicine a reality, with remarkable health and socioeconomic benefits for patients and healthcare systems.

• Promoting cooperation, capacity building and sharing of best practices is crucial to reduce asymmetries between countries, which constrains effective and equitable cross-border personalized medicine.

Cr (VI) reduction by photocatalyic process: Nb2O5 an alternative catalyst

In this study, Nb₂O₅ catalyst was applied in the photocatalytic process for the Chromium reduction. Cr (VI) is a compound classified as highly toxic and often found in industrial tannery effluents. The techniques used for the photocatalytic material characterization were: X-ray diffraction, Specific surface area (B.E.T method), photo-acoustic spectroscopy, Scanning Electron Microscopy (SEM) and X-ray Dispersive Energy Spectrometry (EDS). A comparison between Nb₂O₅ and TiO₂ (widely used in photocatalytic reactions) indicated that Nb₂O₅ has 20% more Cr (VI) reduction than TiO₂. Tests carried out with Nb₂O₅ calcined at 500 °C and with non-calcined Nb₂O₅ showed that the heat treatment did not favor the reaction. Parameters such as pH, radiation intensity, initial concentration of Cr (VI) and amount of catalyst were studied. The results indicated that the acid (pH 2), emitted radiation intensity (250 W), initial concentration Cr (VI) at 10 mg L^-1 and 1.5 g L^-1 Nb₂O₅ non-calcined are the process optimal conditions. In addition, the reuse tests for Nb₂O₅ in consecutive cycles four, were realized. Photostability was maintained at approximately 90% for all cycles when Nb₂O₅ calcined was used. On the other hand, when using Nb₂O₅ non-calcined reduced by 21% during the four tests. This behavior is possibly due to the greater adsorption capacity of the non-calcined material. Making the Nb₂O₅ catalyst attractive for considering larger scale tests.

Integrative taxonomy of Hemimycale (Hymedesmiidae: Poecilosclerida: Demospongiae) from Southeastern Brazil, with the description of two new species

Two new species of Hemimycale from Southeastern Brazil are described in this study with the use of morphological and molecular data. Hemimycale oxeata sp. nov. is orange salmon colored in life and has unique oxeote like tornote spicules in addition to the typical (subtylo-)strongyles of the genus. Hemimycale ceadensis sp. nov. is reddish orange in life and has raised, tiny pore sieves, and subtylostrongyles with asymmetrical ends and raphides as microscleres. The diagnosis of the genus Hemimycale was slightly modified for the inclusion of the new species. Maximum-Likelihood analyses of 18S rRNA and COI sequences resulted in the clustering of both new species with the type species of the genus, thus confirming our morphological identification. The value of anatomical characters of pore sieves for diagnosing species and the genus is discussed. A key for species identification is also furnished.

Genetic divergence of sugarcane varieties collected in the region of Lavras, Minas Gerais, Brazil

Genetic diversity among local accessions and varieties subsidize plant breeding programs, allowing the utilization of existing variability in plants that have already adapted to local climate conditions. An alternative to studying genetic variability is the study of diversity. The aim of this research was to study genetic diversity among sugarcane accessions and varieties used for the production of craft-distilled cachaça (distilled sugarcane alcohol) in the region of Lavras, Minas Gerais, Brazil. Using a one-way design, an experiment was conducted in the municipality of Perdões, Minas Gerais to evaluate 35 regional accessions derived from germplasm collection expeditions and four varieties. Using morphological descriptions of 46 multicategorical sugarcane characteristics, dissimilarity and Tocher cluster method analyses were performed. Based on the results, it was concluded that genetic diversity exists among the accessions evaluated for the target traits.

Effect of traction sutures in the distal esophagus of the rat: a model for esophageal elongation by Foker's method

This study aimed to evaluate a rat model of esophageal elongation using traction sutures by the Foker's method. After esophageal division and closure of the distal segment at approximately 4 mm from the cardia, traction sutures were placed for progressive stretching until the 7(th) postoperative day in the experimental group (n = 10), whilst no traction sutures were placed in the esophagus of the control group (n = 10). Clinical outcome as well as macroscopic and microscopic esophageal morphology were evaluated in both groups. All rats survived the surgical procedure and the anesthetic recovery period. Disruption of sutures during the traction period occurred in 20% of the rats, which required reoperation. Integrity of the stretched esophagus was confirmed at autopsy in all animals. In contrast to the control group, the experimental group showed a significantly more elongated (average length 6.10 +/- 1.10 mm versus 3.91 +/- 0.17 mm, (P = 0.0001)) and thicker esophagus (average mass 35.9 +/- 3.31 mg versus 15.6 +/- 1.71 mg in the control group, P = 0.0001). Histopathological examination showed a relatively well preserved morphology of the stretched esophagus. These observations suggest that esophageal stretching by traction sutures can be undertaken reliably in a rat model, resulting in elongation and mass increase of the stretched esophagus without important tissue damage. As this model mimics Foker's method, it may serve as a useful model in further research studies and may be used to train in surgical technique.

Midterm follow-up of esophageal anastomosis for esophageal atresia repair: long-gap versus non-long-gap

Current approaches to the repair of long-gap esophageal atresia (EA) favor esophageal anastomosis. This investigation provides a midterm follow-up of long-gap EA with a primary repair to determine whether this procedure affects symptom severity and whether symptom severity may predict worsening of dysmotility. Fifteen children at least 1-year post primary repair were divided into group 1 (long-gap) and group 2 (non-long-gap). The severity of their symptoms was graded using a questionnaire focused on their eating habits and gastroesophageal motor dysfunction symptoms. Esophageal transit time and gastric emptying were assessed by scintigraphy and used to grade esophagogastric dysmotility. At midterm follow-up the majority of patients in both groups were asymptomatic (66% in group 1 vs 77.7% in group 2; P > 0.05). Esophagogastric dysmotility grades for group 1 were more severe than for group 2 (median 2.5, range from 1 to 4 vs median 1, range from 1 to 2, respectively; P > 0.05). We found no relationship between the severity of the symptoms and the presence or severity of esophagogastric dysmotility. At midterm follow-up in patients with long-gap atresia that underwent primary repair, this study showed scintigraphic evidence of silent and serious esophagogastric dysmotility in symptom-free or minimally symptomatic children. It may therefore be unreliable to use symptoms in assessing the severity of esophagogastric dysmotility, since both groups showed similar clinical findings but different scintigraphic findings.

Esophageal replacement in rat using porcine intestinal submucosa as a patch or a tube-shaped graft

This study compares the efficacy of porcine intestinal submucosa (SIS) patch graft versus SIS-tube graft in esophageal replacement, using a novel esophageal regeneration model. Clinical function, as well as macroscopic and microscopic morphology were evaluated in both SIS-treated groups. We performed semi-circumferential esophageal excision followed by repair of the defect using either a SIS-patch graft (group I) or segmental esophageal excision followed by a SIS-tube interposition graft (group II) in rats. The 28-day survival rate was significantly different between the SIS-treated groups (100% in group I vs. 0% in group II). Unlike the rats in group II, which died within the first postoperative month due to esophageal dysfunction, all surviving animals in group I resumed a normal solid diet within a few days after surgery, without signs of esophageal dysfunction and gained weight. Barium swallow studies showed no evidence of fistula, significant stenosis or diverticula. No hematological or serum biochemistry abnormalities were found. By day 150 the SIS patch was replaced by esophageal-derived tissues. In the rat model, a patch graft technique using SIS appeared to induce esophageal regrowth and provided an initial and long-term satisfactory function, while a tube-shaped graft technique using SIS was unsuccessful.

Endoscopic obliteration of a recurrent tracheoesophageal fistula with enbucrilate and polidocanol in a child

We present a difficult case of a recurrent tracheoesophageal fistula following primary surgical repair of esophageal atresia. After four unsuccessful attempts to close the fistula, which included three thoracotomies and one endoscopic obliteration using fibrin glue, successful recurrent tracheoesophageal fistula closure was attained with the endoscopic application of enbucrilate (Histoacrylate) combined with polidocanol. Enbucrilate was applied into the lumen of the fistula by bronchoscopy, and polidocanol (Sclerovein) was injected into the esophageal submucosa around the fistula by esophagoscopy. Three years after this treatment, the fistula remains apparently closed.

Intracellular protozoan parasites and apoptosis: diverse strategies to modulate parasite-host interactions

Programmed cell death (apoptosis) is an important regulator of the host's response during infection with a variety of intracellular protozoan parasites. Parasitic pathogens have evolved diverse strategies to induce or inhibit host-cell apoptosis, thereby modulating the host's immune response, aiding dissemination within the host or facilitating intracellular survival. Here, we review the molecular and cell-biological mechanisms of the pathogen-induced modulation of host-cell apoptosis and its effects on the parasite-host interaction and the pathogenesis of parasitic diseases. We also discuss the previously unrecognized phenomenon of apoptotic cell death in (unicellular) protozoan parasites and its potential implications.

Techniques of intestinal transplantation in rat

Two surgical models of intestinal transplantation in the rat are described. One is the implantation of fetal and newborn intestine as free grafts into the omentum of adult recipients, the other the adult intestine transplantation as an accessory graft using vascular anastomoses. A hundred and sixteen small-bowel transplantations were done; 36 of which were fetal intestine (group I), 40 of newborn intestine (group II), and 40 of adult intestine (group III). In the fetal and newborn intestinal transplantation, we emphasize the practices that allowed us to avoid ischemic and traumatic injury to the graft. In the adult intestine transplantation with vascular anastomoses, we heighten the modifications in the surgical technique that made the operation easier and the strategies used to prevent hypothermia and hypovolemic shock. Once experienced with the two chosen surgical techniques, transplantation using an avascular segment became much easier and quicker than transplantation with vascular anastomoses.

Uptake of apoptotic cells drives the growth of a pathogenic trypanosome in macrophages

After apoptosis, phagocytes prevent inflammation and tissue damage by the uptake and removal of dead cells. In addition, apoptotic cells evoke an anti-inflammatory response through macrophages. We have previously shown that there is intense lymphocyte apoptosis in an experimental model of Chagas' disease, a debilitating cardiac illness caused by the protozoan Trypanosoma cruzi. Here we show that the interaction of apoptotic, but not necrotic T lymphocytes with macrophages infected with T. cruzi fuels parasite growth in a manner dependent on prostaglandins, transforming growth factor-beta (TGF-beta) and polyamine biosynthesis. We show that the vitronectin receptor is critical, in both apoptotic-cell cytoadherence and the induction of prostaglandin E2/TGF-beta release and ornithine decarboxylase activity in macrophages. A single injection of apoptotic cells in infected mice increases parasitaemia, whereas treatment with cyclooxygenase inhibitors almost completely ablates it in vivo. These results suggest that continual lymphocyte apoptosis and phagocytosis of apoptotic cells by macrophages have a role in parasite persistence in the host, and that cyclooxygenase inhibitors have potential therapeutic application in the control of parasite replication and spread in Chagas' disease.

Fetal intestinal graft is the best source for intestinal transplantation

Adult intestinal allografts have demonstrated high immunogenicity in human transplantation, making the search for new and more favorable grafts an actual problem. Accepting that fetal and newborn immune systems are relatively immature, their intestines could be ideal sources for organ donation. The purpose of this study was to compare the immunogenicity of fetal, newborn, and adult intestine for selection of the least antigenic. Using a bidirectional rat model for immunologic responses, 116 small-bowel transplantations were done: 36 fetal, 40 newborn, and 40 adult grafts. Two histocompatibility barriers and different immunosuppression regimes were used. For fetal and newborn intestines, free grafts into the omentum of adult recipients were done; for adult intestines, accessory grafts in adult recipients of the same age, using vascular anastomoses. The diagnosis of graft rejection and graft-versus-host disease (GVHD) was based on histology of hematoxylin and eosin-stained biopsies from target organs. Recipients of fetal and newborn grafts did not show signs of GVHD, while 12% of the adult group did (P < 0.05). Rejection was less severe in fetal and adult (P > 0.05) than in newborn (P < 0.05) intestinal transplantation. Treatment with 10 mg/kg per day cyclosporine prevented rejection in 70% of fetal and 75% of adult grafts, while all newborn grafts were rejected. Under no immunosuppression, or with low doses of cyclosporine (2 mg/kg per day), all groups showed histologic signs of rejection in almost all cases, the fetal intestine being the least affected. Concerning histocompatibility barriers, grafts were usually less damaged in the weaker transplantation subgroups. Our data indicate that fetal intestine is the least immunogenic of the three grafts studied, suggesting that it will be the most suitable tissue for organ donation.

Registered designation of origin areas of fermented food products defined by microbial phenotypes and artificial neural networks

Cheese produced from raw ewes' milk and chouriço, a Portuguese dry fermented sausage, are still produced in a traditional way in certain regions of Portugal by relying on colonization by microbial populations associated with the raw materials, equipment, and local environments. For the purpose of describing the product origins and types of these fermented foods, metabolic phenotypes can be used as descriptors of the product as well as to determine the presence of compounds with organoleptic value. The application of artificial neural networks to the metabolic profiles of bacterial isolates was assayed and allowed the separation of products from different regions. This method could then be used for the Registered Designation of Origin certification process of food products. Therefore, besides test panel results for these traditionally produced food products, another tool for validating products for the marketplace is available to the producers. The method can be improved for the detection of counterfeit products.

Increased susceptibility of Fas ligand-deficient gld mice to Trypanosoma cruzi infection due to a Th2-biased host immune response

Infection of BALB/c mice with Trypanosoma cruzi resulted in up-regulated expression of Fas and Fas ligand (FasL) mRNA by splenic CD4+ T cells, activation-induced CD4+ T cell death (AICD), and in Fas: FasL-mediated cytotoxicity. When CD4+ T cells from infected mice were co-cultured with T. cruzi-infected macrophages, onset of AICD exacerbated parasite replication. CD4+ T cells from T. cruzi-infected FasL-deficient BALB gld/gld mice had no detectable AICD in vitro and their activation with anti-TCR did not exacerbate T. cruzi replication in macrophages. However, infection of BALB gld/gld mice with T. cruzi resulted in higher and more prolonged parasitemia, compared to wild-type mice. Secretion of Th2 cytokines IL-10 and IL-4 by CD4+ T cells from infected gld mice was markedly increased, compared to controls. In addition, in vivo injection of anti-IL-4 mAb, but not of an isotype control mAb, reduced parasitemia in both gld and wild-type mice. These results indicate that, besides controlling CD4+ T cell AICD and parasite replication in vitro, an intact Fas: FasL pathway also controls the host cytokine response to T. cruzi infection in vivo, being required to prevent an exacerbated Th2-type immune response to the parasite.

[Bladder rupture in a child with Ehlers-Danlos syndrome phenotype]

We report a case of "spontaneous" bladder rupture in a child with type IV Ehlers-Danlos Syndrome phenotype. The clinical presentation was unusual with abdominal pain, urinary retention and recurrent rectal prolapse. We could not find other similar cases in the literature. We to the possibility of "spontaneous" rupture occurring in this type of patients.

Activation-induced T cell death exacerbates Trypanosoma cruzi replication in macrophages cocultured with CD4+ T lymphocytes from infected hosts

Activation-induced cell death (AICD) of CD4+ T lymphocytes was described in infection with Trypanosoma cruzi, but a role for AICD in modulating parasite spread in host cells has not been investigated. In this study, replication of T. cruzi in vitro in murine macrophage (Mphi) monolayers was investigated. Long term (5 to 13 day) replication of infective (trypomastigote) T. cruzi forms was blocked by supernatants from activated (anti-TCR) CD4+ T cells of infected mice or by rIFN-gamma. However, when CD4+ T cells from infected mice were cocultured with Mphi and activated by anti-TCR, marked exacerbation of trypomastigote growth in Mphi ensued. The deleterious effect required contact between T cells and infected Mphi. Both anti-Fas and TCR activation killed a proportion of CD4+ T cells. Ly-6 activation did not induce AICD and did not exacerbate parasite growth. However, Fas-mediated killing of T cells before Ly-6 activation led to exacerbated parasite growth. Although a minor population, Fas-susceptible cells were the major source of IFN-gamma production by activated T cells. Addition of a neutralizing anti-Fas ligand antibody blocked 50 to 60% of CD4+ T cell AICD and reduced trypomastigote growth in T/Mphi cocultures stimulated by anti-TCR. The results demonstrate that in CD4+ T cells from infected mice, the onset of AICD selectively ablates IFN-gamma production and up-regulates parasite replication in Mphi in vitro. These findings suggest a deleterious role for AICD in T. cruzi infection.

[Pneumoperitoneum in bladder rupture]

Pneumoperitoneum is rarely seen with bladder rupture. In blunt abdominal trauma this sign is strongly suggestive of gastric or bowel perforation. In our child, suspicion of bladder trauma was evoked by car belt marks in the hypogastrium and by gross hematuria. Preoperative diagnosis was not confirmed because immediate surgical exploration was required based on the presence of free air in the abdominal roentgenograph.

Trypanosoma cruzi-induced immunosuppression: selective triggering of CD4+ T-cell death by the T-cell receptor-CD3 pathway and not by the CD69 or Ly-6 activation pathway

In a model of experimental Chagas' disease induced with metacyclic forms of Trypanosoma cruzi, CD4+ but not CD8+ T cells undergo T-cell receptor (TCR)-CD3-mediated activation-induced cell death (AICD) in vitro. CD4+ T cells from T. cruzi-infected mice also developed unresponsiveness in proliferative responses to TCR-CD3-mediated stimulation. A linear correlation was found between extent of proliferative unresponsiveness and loss of CD4+ T-cell viability. CD4+ T-cell activation through the CD69 or Ly-6 A/E pathway, on the other hand, did not result in proliferative unresponsiveness compared with controls. Lack of suppression in proliferation assays correlated with lack of AICD by cells stimulated through the CD69 or Ly-6 A/E pathway. Concomitant stimulation through CD69, however, did not rescue CD4+ T cells from CD3-induced death. Flow cytometry study of cells stimulated in vitro showed no defect in interleukin-2 receptor expression by CD4+ T cells from infected donors, which escaped TCR-mediated AICD. In vivo injection of anti-CD3 into acutely infected mice, but not into control mice, led to splenocyte DNA fragmentation and failed to increase splenic CD4+ T-cell numbers. These results show that TCR-CD3-mediated AICD is involved in CD4+ T-cell unresponsiveness in vitro following infection with T. cruzi. In addition, successful activation of these cells through the CD69 and Ly-6 pathways is due to differences in the inability of these stimuli to trigger AICD. Since TCR-CD3-mediated AICD can be induced in vivo in infected mice, these findings may be relevant for the onset of immunological disturbances in the host.

Partial characterization of the cohemolytic factor produced by Streptococcus uberis and comparison with the CAMP-factor

Exosubstances (cohemolysins) produced by Streptococcus agalactiae (CAMP-factor) and Streptococcus uberis (Uberis-factor) showing hemolytic synergism with beta-lysin produced by Staphylococcus aureus were compared. Cohemolytic activity was evaluated in the supernatants of bacterial cultures, before and after ammonium sulfate precipitation. Sheep erythrocytes sensitized with beta-lysin were used as substrate. The assays were performed in microtiter plates and results were expressed as cohemolytic units/ml. Maximum cohemolytic activity was detected, respectively, after 8 h and 14 h of growth in Columbia broth in S. uberis and S. agalactiae cultures. Cohemolytic activities of both microorganisms showed similarities when submitted to various physical and chemical treatments. They were significantly decreased by heating at 60 degrees C and 100 degrees C, or in presence of trypsin, and were abolished in the presence of Tween 20. Activities were found to be stable in crude supernatants and concentrated preparations maintained at -20 degrees C for 3 months. Differences were related to levels of activity and kinetics of detection during the growth cycle. The results indicate the proteic nature, at least in part, of the Uberis factor. Analysis by PAGE in the presence or absence of SDS allowed us to correlate Uberis activity with a protein band with apparent molecular mass of 42 kDa, while CAMP activity was associated with a protein band of 27 kDa.

Programmed T-cell death in experimental chagas disease

In mature T cells, programmed cell death is thought to serve a regulatory function by limiting both the duration and amplitude of immune responses. Programmed cell death might also be involved in immuno-pathogenesis of certain infectious diseases: recent evidence suggests that programmed T-cell death plays an important role in immune suppression during viral infections. In this article, George DosReis, Maria Evangelina Fonseca and Marcela Lopes review their findings on programmed T-cell death in experimental infection induced by the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease. They also discuss the differential behavior of CD4(+) and CD8(+) T-cell subsets regarding programmed cell death, and same possible pathogenic aspects of host-parasite interaction, where abnormal or exaggerated programmed T-cell death could be involved.

Apoptosis as a cause of T-cell unresponsiveness in experimental Chagas' disease

A murine model of Chagas' disease induced by metacyclic forms of T. cruzi was used to evaluate T-cell function during infection. T-cell unresponsiveness to TcR;CD3 stimulation in vitro and lymphocyte activation in vivo occurred simultaneously. These paradoxical findings are discussed in the light of recent evidence that mature activated T cells become susceptible to TcR-mediated apoptosis. Activation-induced death in T cells from T. cruzi-infected mice has recently been demonstrated in this model. Evidence that TcR-induced death of activated T cells could be a cause for T-cell unresponsiveness in vitro and in vivo, as well as the possible molecular mechanisms involved, are discussed.

Trypanosoma cruzi: both chemically induced and triatomine-derived metacyclic trypomastigotes cause the same immunological disturbances in the infected mammalian host

Infection of BALB/c mice with chemically induced metacyclic forms of Trypanosoma cruzi clone Dm28c led to characteristic changes of experimental Chagas' disease, with protracted but marked parasitemia, intense splenomegaly, and splenic T cell hyporeactivity to TcR;CD3-dependent stimulation. Infection of BALB/c mice with either chemically induced or triatomine-derived Dm28c metacyclic forms led to comparable parasitemias, a synchronous increase in the number of splenic large lymphocytes, and a similar reduction in T cell responsivity to immobile anti-CD3 antibody. A marked and selective reduction in the level of CD8 expression per cell was also seen in mice infected with either form of metacyclic parasites. Large inflammatory mononuclear cell infiltrates were present in the hearts of mice infected with either chemically induced or insect vector-derived metacyclic forms, at both acute and chronic stage, with predominance of CD8 over CD4 T cells in the lesions, in both cases. These results indicate that infection with chemically induced metacyclic forms of T. cruzi can be a useful model of Chagas' disease, resembling infection caused by the insect vector.

Activation-induced CD4+ T cell death by apoptosis in experimental Chagas' disease

Infection of mice with Trypanosoma cruzi, the causative protozoan agent of human Chagas' disease, leads to immunosuppression of the T cell compartment and to chronic cardiac inflammation which resembles the human infection. Recently, reinduction of programmed cell death by apoptosis in mature T cells has been demonstrated. It has been suggested that mature T cell apoptosis could play a role in immunosuppression caused by virus infection. In this report, we have investigated the occurrence of mature T cell apoptosis in murine experimental Chagas' disease. Infection with T. cruzi metacyclic forms led to a relative accumulation of CD8 T cells over CD4 T cells in the spleens of infected mice. Splenic T cells from T. cruzi-infected donors, but not from control littermates, died in vitro upon stimulation with T cell mitogens Con A and anti-TCR-alpha beta mAb in a dose-dependent fashion. DNA fragmentation into nucleosome-sized bands was detected in the supernatants of CD4+ T cells from infected origin, after stimulation with the T cell mitogen Con A. Upon in vitro stimulation with either anti-TCR-alpha beta or Con A, CD4+ T cells were susceptible to elimination, whereas CD8+ T cells were not. Splenic T cells from infected donors were markedly unresponsive to anti-TCR mAb in proliferative assays and underwent apoptosis in vitro, as assessed by electron microscopy. Apoptosis also occurred in vivo in the course of acute infection, as seen by DNA fragmentation in freshly explanted splenic cells and purified T cell subsets. The data indicate that activation-induced CD4+ T cell death by apoptosis is a prominent feature of experimental infection with T. cruzi, and could play a role in immunosuppression and parasite persistence in infected hosts.

Activation-induced CD4+ T cell death by apoptosis in experimental Chagas' disease

Infection of mice with Trypanosoma cruzi, the causative protozoan agent of human Chagas' disease, leads to immunosuppression of the T cell compartment and to chronic cardiac inflammation which resembles the human infection. Recently, reinduction of programmed cell death by apoptosis in mature T cells has been demonstrated. It has been suggested that mature T cell apoptosis could play a role in immunosuppression caused by virus infection. In this report, we have investigated the occurrence of mature T cell apoptosis in murine experimental Chagas' disease. Infection with T. cruzi metacyclic forms led to a relative accumulation of CD8 T cells over CD4 T cells in the spleens of infected mice. Splenic T cells from T. cruzi-infected donors, but not from control littermates, died in vitro upon stimulation with T cell mitogens Con A and anti-TCR-alpha beta mAb in a dose-dependent fashion. DNA fragmentation into nucleosome-sized bands was detected in the supernatants of CD4+ T cells from infected origin, after stimulation with the T cell mitogen Con A. Upon in vitro stimulation with either anti-TCR-alpha beta or Con A, CD4+ T cells were susceptible to elimination, whereas CD8+ T cells were not. Splenic T cells from infected donors were markedly unresponsive to anti-TCR mAb in proliferative assays and underwent apoptosis in vitro, as assessed by electron microscopy. Apoptosis also occurred in vivo in the course of acute infection, as seen by DNA fragmentation in freshly explanted splenic cells and purified T cell subsets. The data indicate that activation-induced CD4+ T cell death by apoptosis is a prominent feature of experimental infection with T. cruzi, and could play a role in immunosuppression and parasite persistence in infected hosts.

[Transoperative anatomopathologic examinations: quality control]

Frozen sections (FS) are usually performed in a General Hospital and are very useful for the surgical procedure orientation. PURPOSE--To verify the accuracy of the FS performed at the Hospital de Clínicas de Porto Alegre (HCPA), RS, Brazil. METHOD--2,152 FS were carried out between March 1986-September 1991, in a prospective study. RESULTS--3.7% of the conventional pathologic examinations (58,127), performed in the same period, correspond to the FS examined. When the FS diagnosis differed from the definitive one (in paraffin) it was classified as False Positive (0.4%), False Negative (1.8%) or inconclusive (2.8%). The organs more frequently examined were lymph nodes (19.3%), ovary (17.21%), breast (16.6%) and thyroid gland (12.4%). We observed accuracy indices in 95% of the FS examined, and in 97.8% when excluding the inconclusive ones. CONCLUSION--The accuracy indices of FS performed in HCPA were similar to the ones found in the literature, which vary from 90.4% to 98.5%.

Trypanosoma cruzi-induced immunosuppression: blockade of costimulatory T-cell responses in infected hosts due to defective T-cell receptor-CD3 functioning

A model of experimental Trypanosoma cruzi murine infection with chemically induced metacyclic forms (opossum clone Dm28c) showed a marked state of T-cell unresponsiveness during acute phase, but lacked evidence of suppressor cell activity. Spleen cells from infected mice were suppressed in vitro in responses to T-cell activators concanavalin A, anti-Thy1 monoclonal antibody (MAb), and anti-CD3 MAb compared with spleen cells from control littermates. Activation with accessory cell-independent stimulus provided by immobilized anti-CD3 was defective in splenic CD4-positive T cells from infected mice, but not in such cells from control mice. No evidence of splenic suppressor cell activity was found in cell-mixing experiments using nylon-passed T cells from control and infected donors. Kinetic experiments showed that there was a discrete stage in infection when T cells were already suppressed in response to anti-CD3 but still responded to anti-CD69 MAb. In these T cells, immobilized anti-CD3 failed to enhance simultaneous CD69 responses, although anti-CD3 enhanced CD69 responses in control T cells from uninfected donors. These results demonstrate an intrinsic defect in T-cell receptor-mediated T-cell activation, which could be a mechanism generating T-cell suppression during infection by T. cruzi.