Protection of vascular endothelium by aspirin in a murine model of chronic Chagas’ disease

Chronic Chagas’ disease affects 10–30 % of patients infected with Trypanosoma cruzi, and it mainly manifests as cardiomyopathy. Important pathophysiological mechanisms involved in the cardiac lesions include activation of the endothelium and induced microvascular alterations. These processes involve the production of endothelial adhesion molecules and thromboxane A₂, which are involved in inflammatory cell recruitment and platelet aggregation, respectively. Cyclooxygenase inhibitors such as aspirin decrease thromboxane production and alter the course of Chagas’ disease, both in the acute and chronic phases. We studied the effects of the administration of low and high doses of aspirin during the early phase of T. cruzi infection, following microvascular damage in the context of a chronic murine model of Chagas’ disease. The effects of both schedules were assessed at 24 and 90 days postinfection by evaluating parasitemia, mortality, and cardiac histopathological changes as well as the expression of ICAM, VCAM, and E-selectin in cardiac tissue. Thromboxane A₂, soluble ICAM, and E-selectin blood levels were also measured. While aspirin did not affect parasitemia or mortality in the infected mice, it decreased both cardiac inflammatory infiltrates and thromboxane levels. Additionally, at 90 days postinfection, aspirin normalized sICAM and sE-selectin levels. Considering the improved endothelial function induced by aspirin, we propose the possibility of including this drug in clinical therapy to treat chronic Chagas’ disease.     

Chemotherapy of chronic indeterminate Chagas disease: a novel approach to treatment

Treatment of Chagas disease is a controversial issue because the available drugs are highly toxic. Clomipramine is a tricyclic antidepressant drug that inhibits Trypanosoma cruzi's trypanothione reductase, provoking the death of the parasite and preventing the cardiac damage when used for the treatment of acutely infected mice. Here, we studied the effectiveness of clomipramine (5 mg/kg/day for one month) as chemotherapy for T. cruzi-infected mice in the chronic indeterminate stage of the infection. The animals were analyzed in the cardiac chronic phase. Survival of treated animals was 84% while for the untreated ones was 40%; most of the animals presented electrocardiographic abnormalities. Affinity and density of cardiac beta receptors from infected and treated mice were similar to those in the indeterminate phase, showing that clomipramine treatment stopped the increment of functional alterations provoked by the infection, while untreated mice presented affinity and density significantly diminished. Hearts from infected and untreated mice in the chronic stage presented mononuclear cells, necrosis and fiber dissolution while hearts from treated animals showed only isolated inflammatory infiltrates. Present results demonstrate that clomipramine used in the chronic indeterminate phase of the T. cruzi infection modified the natural evolution of the chagasic cardiopathy.     

Benznidazole therapy during acute phase of Chagas disease reduces parasite load but does not prevent chronic cardiac lesions

The goals of this study were to evaluate the efficacy of benznidazole (Bz) treatment in decreasing of the parasitic load during the acute phase of experimental Chagas disease and to analyze its influence in the development of cardiac chronic alterations in mice inoculated with drug-resistant Trypanosoma cruzi strains. Our results showed that the early Bz treatment (started at 4th day of infection) was efficient in reducing the parasite load in animals from both acute and chronic phase of the infection. Moreover, this reduction in the parasite load could not be associated with the intensity of the cardiac chronic lesions. The histopathological evaluation of cardiac tissue of Bz-treated mice showed three different patterns of response: (1) presence of a small number of inflammatory cells and fibrotic area similar to noninfected mice; (2) similar intensity of inflammatory infiltrate and smaller fibrotic area in relation to nontreated animals; (3) similar intensity of inflammatory infiltrated and fibrosis area among the Bz-treated and nontreated animals. Each specific pattern was obtained with different T. cruzi strain, suggesting that the pattern of the heart lesions in chronic phase of Bz-treated animals was T. cruzi strain dependent but not related with drug resistance levels.     

Autoantibodies to Neurotrophic Receptors TrkA,TrkB and TrkC in Patients with Acute Chagas’ Disease

Neurotrophic receptors TrkA and TrkC double up as receptors that Trypanosoma cruzi uses to invade cells and as autoantigen in T. cruzi‐infected individuals (with Chagas’ disease). Consequently, autoantibodies against TrkA and TrkC (ATA) potently block T. cruzi invasion in vitro and in ATA‐immunized mice. Thus, ATA could keep T. cruzi invasion in check in Chagas’ disease. However, ATA has been examined only in patients with chronic Chagas’ disease. To determine whether ATA potentially participate in the early stage of infection, we analysed the sera of 15 patients with acute Chagas’ disease, 4–66 years of age. We find that all sera contain high antibody titres to TrkA, TrkB and TrkC, but not to other growth factor receptors, indicating that ATA are produced relatively soon after T. cruzi infection by an age‐independent process. One individual, who acquired the disease after an accidental laboratory infection, converted to Trk‐antibody (Ab)‐seronegative when progressing to the chronic phase. ATA from acute patients were of low avidity (K₀ <24.8 × 10^?8 m ) and of IgM and IgA isotypes. In contrast, ATA from chronic patients were of high avidity (K_o = 1.4 to 4.5 × 10^?8 m ) and of the IgG2 isotype. Therefore, ATA underwent affinity maturation and class switch when patients progressed from acute to chronic disease. Thus, it may be that Trk autoimmunity, which starts in the acute Chagas’ disease, plays a role in attenuating parasitemia and tissue parasitism that characterizes the acute/chronic phase transition of Chagas’ disease.     

Differential tissue distribution of diverse clones of Trypanosoma cruzi in infected mice

Chagas disease, caused by the protozoan Trypanosoma cruzi, presents variable clinical course but the phenomena underlying this variability remain largely unknown. T. cruzi has a clonal population structure and infecting strains are often multiclonal. T. cruzi genetic variability could be a determinant of differential tissue tropism or distribution and consequently of the clinical forms of the disease. We tested this hypothesis by using low-stringency single specific primer polymerase chain reaction (LSSP-PCR) to type genetically the parasites in tissues of experimental infected mice. BALB/c mice were simultaneously inoculated with two different T. cruzi populations (JG strain and Col1.7G2 clone). Doubly infected animals showed clear differential tissue distribution for the two populations (chronic phase). Our results indicate a significant influence of the genetic polymorphism of infecting T. cruzi populations in the pathogenesis of chronic Chagas disease.     

Differential tissue distribution of diverse clones of Trypanosoma cruzi in infected mice.

Chagas disease, caused by the protozoan Trypanosoma cruzi, presents variable clinical course but the phenomena underlying this variability remain largely unknown. T. cruzi has a clonal population structure and infecting strains are often multiclonal. T. cruzi genetic variability could be a determinant of differential tissue tropism or distribution and consequently of the clinical forms of the disease. We tested this hypothesis by using low-stringency single specific primer polymerase chain reaction (LSSP-PCR) to type genetically the parasites in tissues of experimental infected mice. BALB/c mice were simultaneously inoculated with two different T. cruzi populations (JG strain and Col1.7G2 clone). Doubly infected animals showed clear differential tissue distribution for the two populations (chronic phase). Our results indicate a significant influence of the genetic polymorphism of infecting T. cruzi populations in the pathogenesis of chronic Chagas disease.     

Effects of endurance exercise on ventral tegmental area neurons in the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid-treated mice

Loss of dopaminergic neurons in the substantia nigra (A9 cells) and ventral tegmental area (VTA) (A10 cells) has been reported in Parkinson's disease with reference to causing motor and non-motor deficits, although clinical and laboratory animal studies on the degeneration of VTA neurons are less emphasized comparative to the degeneration of substantia nigra neurons. In the present study, we examined the VTA dopaminergic neurons in a chronic mouse model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid at a level showing moderate neurodegeneration and studied the impact of endurance exercise on VTA neurons in this model. In comparison to the normal control animals, the chronic mouse model of Parkinson's disease with moderate neurodegeneration demonstrated a significant reduction of VTA neurons (52% loss), when these animals were kept sedentary throughout the study. Morphologically, the VTA dopaminergic neurons in this model displayed a decrease in cell volume and showed irregular or disparaging axonal and dendritic projections. When the chronic Parkinsonian mice were exercised on a motorized rodent treadmill up to 15 m/min, 40 min/day, 5 days/week for 10 and 18 weeks, the total number of VTA dopaminergic neurons were significantly higher than the sedentary Parkinsonian animals. Especially noted with the 18-week exercised Parkinsonian mice, the number of VTA neurons returned to normal range and the cells were densely populated and displayed distinctive axons and dendritic arborization. These results demonstrate that prolonged exercise training is neuroprotective to the dopaminergic neurons in the VTA of the chronic mouse model of Parkinson's disease with moderate neurodegeneration.     

Chronic aspirin use and survival following sepsis—A propensity-matched,observational cohort study

ObjectivesThe use of antiplatelet agents is postulated to lead to improved outcomes in sepsis. We aimed to evaluate whether chronic, pre-hospitalization aspirin use leads to improved outcomes in patients with sepsis.MethodsWe conducted an observational cohort study among patients with sepsis, hospitalized in internal medicine wards in a single university-affiliated medical center. A propensity-score model was used to match and compare patients on chronic aspirin use to non-users. Patients with established cardiovascular disease were excluded. The primary outcome was survival rates at 30 days. Secondary outcomes included survival rates at 90 days, days of fever, length of hospital stay, and hospital readmission within 90 days.ResultsA total of 1671 patients fulfilled the inclusion criteria. 533 chronic aspirin users were matched to 533 aspirin non-users. Survival rates were significantly higher among patients on chronic aspirin use (hazard ratio (HR) 0.67; 95% CI, 0.51–0.89)). This effect was highlighted in several subgroups of patients, as patients with chronic obstructive pulmonary disease (COPD) or those with chronic use of beta blockers showed the greatest survival benefit with aspirin use. Patients in the aspirin group also showed significantly higher 90 days survival rates (HR 0.69; 95% CI, 0.57–0.92; p = 0.006) and experienced less days of fever in comparison to the control group.DiscussionPre-hospitalization treatment with aspirin for patients without established cardiovascular disease may be associated with mortality reduction, as shown in this is hypothesis-generating single center observational study.     

Effect of zinc supplementation on E-ADA activity,seric zinc,and cytokines levels of Trypanosoma evansi infected wistar rats

The aim of this study was to evaluate the effect of zinc supplementation on the ecto-adenosine deaminase activity (E-ADA), zinc seric levels and cytokines (TNF-α, IL-1, IL-6, and IL -10) on rats experimentally infected by Trypanosoma evansi. Four groups with 10 rats each were used as negative controls (groups A and B), while the animals from the groups C and D were infected intraperitoneally with 0.1 mL of cryopreserved blood containing 1.4 × 10⁴ of trypanosomes. Animals of groups B and D received two doses of Zinc (Zn) at 5 mg kg⁻¹, subcutaneously, on the 2nd and 7th day post-infection (PI). Blood samples were collected on days 5 (n = 5) and 15 PI (n = 5). Zn supplementation was able to increase the rat's longevity and to reduce their parasitemia. It was observed that seric Zn levels were increased on infected animals under Zn supplementation. Animals that were infected and supplemented with Zn showed changes in E-ADA activity and in cytokine levels (P < 0.05). Zn supplementation of healthy animals (Group B), increased the E-ADA activity, as well as reduced the concentration of cytokines. Infected animals from groups C and D showed increased levels of cytokines. Finally, we observed that Zn supplementation led to a modulation on cytokine's level in rats infected by T. evansi, as well as in E-ADA activity.     

Effect of acute and chronic administration of 1,2,3,4-tetrahydroisoquinoline on muscle tone,metabolism of dopamine in the striatum and tyrosine hydroxylase immunocytochemistry in the substantia nigra,in rats

The effects of acute and chronic administration of 1,2,3,4-tetrahydroisoquinoline, an endogenous substance suspected of producing parkinsonism in humans, on the muscle tone and metabolism of dopamine in the striatum, and on the number of tyrosine hydroxylase-immunoreactive cells in the substantia nigra were investigated in rats. Muscle tone was examined using a combined mechanomyographic and electromyographic method which measured simultaneously the muscle resistance of the rat's hind foot to passive extension and flexion in the ankle joint and electromyographic activity of the antagonistic muscles of that joint: gastrocnemius and tibialis anterior. 1,2,3,4-Tetrahydroisoquinoline administered at doses of 50 and 100 mg/kg intraperitoneally for 19 days increased muscle resistance 1 h after the first injection (acute treatment), 1 h after the last injection (chronic treatment) and three days after compound withdrawal. Rigidity observed on the third day of 1,2,3,4-tetrahydroisoquinoline withdrawal was accompanied by an increased tonic (resting) electromyographic activity of the gastrocnemius and tibialis anterior muscles. At the same time, a significant reduction in the number of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra and a decrease in the dopamine level in the striatum were also found. A declining number of tyrosine hydroxylase-immunoreactive neurons in the whole substantia nigra showed a significant negative correlation with the enhanced muscle resistance, as well as with the tonic electromyographic activity recorded at rest, i.e. before the start of movements, from the gastrocnemius and tibialis anterior muscles.Our results suggest that 1,2,3,4-tetrahydroisoquinoline may be one of the endogenous substances involved in the progress of Parkinson's disease.     

The treatment with selenium increases placental parasitismin pregnant Wistar rats infected with the Y strain of Trypanosoma cruzi

Selenium (Se) is an essential micronutrient in the diet of mammals and has an important role in the immune function. Selenium is a key element in selenoproteins involved in the in the maintenance of the antioxidant defense. Diet with selenium is beneficial for the treatment of diseases correlated with high levels of oxidative stress, also observed in the Chagas disease. Chagas disease is a neglected disease caused by the protozoan Trypanosoma cruzi and several research groups are focused on the illness treatment. Immunomodulation of the infection using microelements is an important tool to avoid deleterious effects of the Chagas disease. Therefore, our objective was to evaluate the effects of selenium supplementation on pregnant Wistar rats infected with T. cruzi. Selenium treatment stimulated the weight and length of fetuses and placentas allied to the decrease of blood parasitemia. However, selenium demonstrated a low influence on T cells, diminishing the B cell population (CD45RA⁺). Moreover, the production of pro-inflammatory cytokines was downregulated under selenium administration. Low pro-inflammatory cytokines levels probably are related to the increase in the number of amastigote nests in infected and treated animals. Thus, selenium supplementation during pregnancy could impair the local placental immune response. Further studies are necessary to assess the interaction between selenium and the acute Chagas’ disease during pregnancy, which will base future supplementation strategies.     

Trypanosoma cruzi: experimental parasitism in the central nervous system of albino mice

Trypanosoma cruzi causes a pan-infection, Chagas disease, in American mammals through fecal transmission by triatomine insects, resulting in an acute phase parasitemia with intracellularity mainly in the myocells and cells of the central nervous system (CNS).The parasites, due to the immune response, then decrease in number, characteristic of the life-long chronicity of the disease. We infected a mouse model with isolates obtained from reservoirs and vectors from rural and urban endemic areas in Venezuela. Intracellular proliferation and differentiation of the parasite in astrocytes, microglia, neurons, endothelial cells of the piarachnoid, cells of the Purkinje layer, and spinal ganglion cells, as well as extracellularly in the neuropil, were evaluated during the acute phase. Damages were identified as meningoencephalitis, astrocytosis, reactive microglia, acute neuronal degeneration by central chromatolysis, endothelial cell hyperplasia, edema of the neuropil, and satellitosis. This is the first time that satellitosis has been reported from a mammal infected with T. cruzi. Intracellular T. cruzi and inflammatory infiltrates were found in cardiac and skeletal myocytes and liver cells. No parasitism or alterations to the CNS were observed in the chronic mice, although they did show myocarditis and myocitis with extensive infiltrates. Our results are discussed in relation to hypotheses that deny the importance of the presence of tissue parasites versus the direct relationship between these and the damages produced during the chronic phase of Chagas disease. We also review the mechanisms proposed as responsible for the nervous phase of this parasitosis.     

Effects of different doses of nandrolone decanoate on estrous cycle and ovarian tissue of rats after treatment and recovery periods

This study tested the hypothesis that different doses of nandrolone decanoate (ND) will cause changes in the estrous cycle and ovarian tissue of adult rats; and investigated the duration of the recovery period that is sufficient to restore the damage in the animals treated with different doses. Wistar rats were treated with ND at doses of 1.87, 3.75, 7.5 and 15 mg/kg body weight, or received mineral oil (control group) for 15 days, subcutaneously. All animals were divided into three groups according to the treatment periods: (i) ND treatment for 15 days; (ii) ND treatment followed by a 30‐day recovery; and (iii) ND treatment followed by a 60‐day recovery. Estrous cycle was monitored daily, and at the end of each period, the animals were euthanized for histopathological analysis. During ND treatment and after 30‐day recovery, all animals exhibited persistent diestrus. After a 60‐day recovery, persistent diestrus was only maintained in the group that had received the highest dose. Ovarian weight was decreased significantly after the 30‐day recovery, regardless of ND doses, compared with the control group. There was a reduction (P < 0.05) in the number of corpora lutea and antral and growing follicles, in contrast to an increase (P < 0.05) in atretic follicles in a dose‐ and time‐dependent manner. Remarkable histopathological changes occurred in the ovaries of all ND‐treated groups. In conclusion, the different doses of ND caused changes in the estrous cycle and ovarian tissue of rats, and recovery periods (30 and 60 days) were insufficient to completely restore the damage in the animals treated with the highest dose.     

Histopathologic features of phorbol myristate acetate-induced lung injury

Rabbits given daily intravenous injections of phorbol myristate acetate (PMA) develop acute and chronic pulmonary disease. We distinguished three phases in the histologic progression of the lung injury. An acute phase (occurring within 1.5 hours of the first injection) involved hemorrhagic pneumonitis, increased lung weight, and increased numbers of neutrophils as well as erythrocytes in alveolar fluid. The intermediate phase (occurring 1 to 7 days after the initial injection) involved interstitial pneumonitis: neutrophils and macrophages infiltrated into lung interstitium and alveolar fluid. The relative number of type II alveolar epithelial cells increased dramatically and lung weight became maximal during this phase. In the chronic phase (occurring within 14 days and lasting greater than 77 days) diffuse interstitial fibrosis progressed, whereas inflammatory changes abated. Animals treated daily with PMA developed a linear increase in lung hydroxyproline content beginning on the 7th day of treatment. Values increased to three to four times above controls by day 77. Animals treated with PMA for only 14 days and sacrificed up to 63 days thereafter had lung hydroxyproline values that were intermediate between controls and animals injected daily for 77 days. Their fibrosis neither progressed nor reversed when PMA treatment was stopped. In contrast, animals receiving a single dose of PMA developed only the acute and intermediate phases of injury; no detectable fibrosis occurred, and their lung reactions resolved completely. Finally, animals made neutropenic with nitrogen mustard did not respond to PMA with increased lung weight or changes in alveolar lavage fluid cellularity during the early or intermediate phases of the disease. They did, however, exhibit increased interstitial cellularity. Thus, PMA produces abrupt pneumonitis that progresses to fibrosis. The acute and intermediate phases of injury are neutrophil dependent and reversible, whereas the chronic fibrotic phase is irreversible and requires continued PMA injections for progression.     

CagA in Barrett's oesophagus in Colombia, a country with a high prevalence of gastric cancer

BACKGROUND: In the USA, atrophic gastritis and gastric cancer are rare, whereas gastro-oesophageal reflux disease (GERD) is common. Infection with Helicobacter pylori, especially a CagA positive strain, is unusual in patients with GERD/Barrett's oesophagus in the USA. AIM: To examine the relation between Barrett's oesophagus and CagA positive H pylori in Colombia, a country with a high prevalence of CagA positive H pylori associated atrophic gastritis and gastric cancer. METHODS: Helicobacter pylori and CagA status was determined among Colombian patients with long segment Barrett's oesophagus and a control group with simple H pylori gastritis. Helicobacter pylori status was determined using a triple stain and CagA status was determined by immunohistochemistry using a specific rabbit anti-CagA serum. RESULTS: Gastric and oesophageal mucosal biopsies were obtained from 51 patients--39 men (mean age, 57.8 years; SD, 13.1) and 12 women (mean age, 51.8 years; SD, 14.4)--with documented long segment Barrett's oesophagus. The results were compared with 24 Colombian patients with H pylori gastritis without oesophageal disease. Thirty two patients with Barrett's oesophagus had active H pylori infection. CagA status was evaluated in a subset of 23 H pylori infected patients with Barrett's oesophagus, and was positive in eight of these patients compared with 19 of 24 controls (p = 0.01). CONCLUSIONS: Although most Colombian patients with Barrett's oesophagus had H pylori infection, CagA positive infections were unusual. These data illustrate how consistent corpus inflammation reduces acid secretion, which prevents Barrett's oesophagus among those with abnormal gastro-oesophageal reflux barriers.     

Association of clomipramine and allopurinol for the treatment of the experimental infection with Trypanosoma cruzi

We have previously shown that clomipramine and allopurinol used separately are effective in preventing chronic chagasic cardiomyopathy. The aim of the present study was to evaluate the effect of the association of clomipramine (Clo—5 mg/kg/day/90 days) and allopurinol (Allo—5, 10, or 15 mg/kg/day/90 days) for the treatment of experimental Chagas disease in the acute stage. Treatment effectiveness was evaluated through parasitemia, survival, electrocardiography, serology, and cardiac histopathology. Groups treated showed no electrocardiographic abnormalities, in contrast to those untreated which presented 25% of mice with conduction alterations. The myocardium of treated mice (Clo, Allo10+Clo, and Allo15+Clo) presented no structural alterations. Cardiac b-receptor affinity was preserved in mice treated with Clo or Clo+Allo at the different doses; receptor density of the Clo and Allo15+Clo groups did not differ from the non-infected group. Anti-cruzipain antibody levels were similar in treated and untreated groups. Survival was significantly increased in the treated groups (p < 0.05), with Clo and all the Clo+Allo groups presenting the highest rates. These results show that the association of clomipramine + allopurinol is effective for Chagas disease treatment and has the same effect as clomipramine alone.     

Functional and neurochemical changes of the gastrointestinal tract in a rodent model of Parkinson's disease

Patients with Parkinson's disease develop motor disturbances often accompanied by peripheral autonomic dysfunctions, including gastrointestinal disorders, such as dysphagia, gastric stasis and constipation. While the mechanisms subserving enteric autonomic dysfunctions are not clearly understood, they may involve the enteric dopaminergic and/or nitrergic systems. In the present study, we demonstrate that rats with unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons develop a marked inhibition of propulsive activity compared to sham-operated controls, as indicated by a 60% reduction of daily fecal output at the 4th week of observation. Immunohistochemical data revealed that 6-hydroxydopamine treatment did not affect the total number of HuC/D-positive myenteric neurons in both the proximal and distal segments of ileum and colon. Conversely, in the distal ileum and proximal colon the number of nitrergic neurons was significantly reduced. These results suggest that a disturbed distal gut transit, reminiscent of constipation in the clinical setting, may occur as a consequence of a reduced propulsive motility, likely due to an impairment of a nitric oxide-mediated descending inhibition during peristalsis.     

Is a negative correlation between sTNFR1 and TNF in patients with chronic Chagas disease the key to clinical progression?

Soluble TNF receptors (sTNFR1 and sTNFR2) are natural endogenous inhibitors of TNF and are elevated in inflammatory, autoimmune, and chronic degenerative diseases. In Chagas disease, pleiotropic cytokine TNF is considered key in immunopathology. Thus, we aimed to evaluate the levels of TNF, sTNFR1, and sTNFR2 in the serum of patients with chronic Chagas disease. TNF and its soluble receptors were quantified using Cytometric Bead Array in the serum of 132 patients, of which 51 had the indeterminate form (IND), 39 the mild cardiac form (CARD 1), 42 the severe cardiac form (CARD 2), and 20 non-infected individuals (NI). The results indicate that the soluble receptors may regulate TNF in Chagas disease, as their leves were higher in T. cruzi-infected individuals when compared to non-infected individuals. We found a moderate negative correlation between sTNFR1 and TNF in individuals with the IND form, suggesting a relationship with non-progression to more severe forms, such as heart disease. sTNFR1 and sTNFR2 were increased in all clinical forms, but with a moderate positive correlation in more severe patients (r = 0.50 and p = 0.0005). TNF levels showed no statistical differences in the groups of patients. These findings suggest the importance of the endogenous balance of the levels of soluble TNF receptors in the protection and balance in patients with chronic Chagas disease, besides revealing the immunological complexity in chronic T. cruzi-infected individuals.     

Chagas disease: a threat to safe blood transfusion

Chagas disease affects approximately 8 million infected people in Mexico and Central and South America and causes 12 500 deaths annually; 41 200 new cases are reported annually (2006). Coordinated multicenter programmes have decreased about 70% of new infections in South America due to the interruption of vectorial and decreased blood transfusion transmissions. Migration of the infected population from rural areas to urban centres in endemic and non-endemic countries led to the urbanization and globalization of Chagas disease. Chagas disease is now an emerging disease in non-endemic areas, where congenital, blood and organ transplant transmissions are associated with reactivation of chronic Chagas disease in patients under immunosuppression or HIV infection. Recent initiatives in non-endemic countries have been implemented to control its transmission by blood transfusion and transplants of organs. Most of the infected people were asymptomatic individuals in the chronic phase of the disease, characterized by and low and intermittent parasitemia and diagnosed by serological tests. In endemic countries, universal mandatory screening tests for detection of Trypanosoma cruzi antibodies dramatically reduced blood transfusion transmission. In non-endemic countries, where transfusion represents the most important way of transmission, different strategies have been registered: (1) blood donor selection and deferral; (2) blood donation testing; (3) blood donation testing in people who lived in endemic areas. Questionnaires containing well-defined questions help to identify patients from endemic areas and their epidemiological data but are of limited value since they depend on donor information. High-performance serologic tests were reported for the detection of anti-T. cruzi antibodies like ELISA with epimastigotes or trypomastigotes or recombinant antigens, chemiluminescent, immunoblot and radioimmunoprecipitation assays. Almost 100% of sensitivity and specificity were registered when tested in samples of well-defined chronic chagasic patients but gold standards are not validated in circumstances of low prevalence of the disease. Additionally, their value in cases of inconclusive results (one positive test and other negative or doubtful results) was not known. Unfortunately, molecular methods are less sensitive than serology for the chronic phase of the disease (45–100% sensitivity) and were not reliable for screening tests in blood banks. Perspectives of the reduction of parasites by photochemical treatment and ultraviolet (crystal violet, methylene blue, amotosalen, riboflavin, thiopirilium) were reported sometimes with slight changes in the blood products. However, the main challenge is to demonstrate their value for prevention of a broad spectrum of agents transmitted by blood transfusion (including príon disease) and inactivation of low parasite load. In summary, questionnaires including specific questions about donor epidemiology and high-performance serologic tests have been useful for blood bank screening. The cost–benefit–effectiveness analyses of universal serologic screening vs. serologic screening of selected donors depend on the prevalence of positive donors and should be evaluated in different regions. Finally, as pathogen inactivation methods may represent remarkable improvement in blood bank transfusion, efforts from the academia are necessary to prove their safety and effectiveness, and from blood banking–transfusion medicine community and public regulators to their implementation aiming to increase the safety of blood transfusion for patients around the world.     

Cavia porcellus as a model for experimental infection by Trypanosoma cruzi

The guinea pig (Cavia porcellus) is a natural reservoir for Trypanosoma cruzi but has seldom been used as an experimental infection model. We developed a guinea pig infection model for acute and chronic Chagas disease. Seventy-two guinea pigs were inoculated intradermally with 10(4) trypomastigotes of T. cruzi strain Y (experimental group); 18 guinea pigs were used as control group. Eight animals from the experimental group and two from the control group were sacrificed 5, 15, 20, 25, 40, 55, 115, 165, and 365 days after inoculation. During the acute phase (15 to 55 days), we observed parasitemia (with a peak on day 20) and positive IgM and IgG Western blots with anti-shed acute-phase antigen bands. The cardiac tissue showed vasculitis, necrosis (on days 40 to 55), moderate to severe inflammation, and abundant amastigote nests. Smaller numbers of amastigote nests were also present in kidney, brain, and other organs. In the early chronic phase (115 to 165 days), parasitemia disappeared and anti-T. cruzi IgG antibodies were still detectable. In cardiac tissue, the number of amastigote nests and the grade of inflammation decreased. In the chronic phase (365 days), the cardiac tissue showed vasculitis and fibrosis; detectable parasite DNA was associated with higher grades of inflammation. The experimental T. cruzi infection model in guinea pigs shows kinetics and pathologic changes similar to those of the human disease.