Anti-Trypanosoma cruzi antibody profiling in patients with Chagas disease treated with benznidazole assessed by genome phage display

BACKGROUND

There have been significant improvements in Chagas disease therapy and it is now widely accepted that most patients with chronic disease might benefit from therapy. However, there are challenges to monitor drug efficacy and cure for these patients, which are important impediments for current and future therapies. Trypanosoma cruzi-PCR is highly variable while IgG seroconversion takes decades yielding variable results depending on the antigen(s) used for the assay.

METHODS AND RESULTS

We used the genomic phage display (gPhage) platform to perform a pairwise comparison of antigens and epitopes recognized by twenty individual patients with chronic Chagas disease before and after treatment with benznidazole. In total, we mapped 54,473 T. cruzi epitopes recognized by IgG from individual patients (N = 20) before benznidazole treatment. After treatment, the number of epitopes recognized by all patients was significantly smaller (21,254), a reduction consistent with a decrease in anti-T. cruzi antibodies. Most of these epitopes represent distinct fragments from the same protein and could, therefore, be grouped into 80 clusters of antigens. After three years of treatment with benznidazole, we observed a 64% reduction in the number of clusters of antigens recognized by patients (59 clusters before versus 21 clusters after treatment). The most abundant antigenic clusters recognized by patients correspond to the surface antigen CA-2 (B13) followed by the microtubule associated antigen, which highlights the value of these epitopes in Chagas disease diagnosis. Most importantly, quantitative pairwise comparison of gPhage data allowed for the prediction of patient response to treatment based on PCR status.

PRINCIPAL FINDING

Here, we compiled a list of antigens and epitopes preferentially recognized by Chagas disease patients before and after benznidazole treatment. Next, we observed that gPhage data correlated with patient PCR-status and could, therefore, predict patient response to treatment. Moreover, gPhage results suggest that overall, independent of PCR status, treatment led to a reduction in the presence of T. cruzi-specific antibody levels and the number of antigens and epitopes recognized by these patients.

CONCLUSION

The gPhage platform use of unbiased library of antigens, which is different from conventional serological assays that rely on predetermined antigens, is a contribution for the development of novel diagnostic tools for Chagas disease.

Serological screening for Chagas disease in an endemic region of Northern Minas Gerais, Brazil: the SaMi-Trop project

Chagas disease (CD) is still a neglected disease. Infected individuals are diagnosed late, being treated in worse clinical conditions. Thus, this study aimed to analyze the prevalence and the factors associated with new confirmed cases of CD identified by serological screening in an endemic region of Minas Gerais State, Brazil. This is an analytical cross-sectional study with data from a project of the Research Center in Tropical Medicine of Sao Paulo- Minas Gerais (SaMi-Trop) conducted in two municipalities. Data collection included a questionnaire with closed questions, a venous blood collection and an ELISA serological test for CD. A total of 2,038 individuals with no previous diagnosis of CD participated in the study. The result of the serological test for CD was adopted as the dependent variable. The independent variables addressed personal issues, health conditions and lifetime housing. A descriptive analysis of individual variables was performed. Subsequently, a bivariate analysis was performed using the Pearson’s chi-square test. Households sheltering individuals positive for CD were georeferenced, and the analysis of spatial distribution was performed using the quartic function to estimate the density of the nucleus. Among the participants, 188 (9.2 %) were positive for CD. The profile of participants with CD was associated with place of residence, age, relative/family member with CD and living conditions. It is noteworthy that there are still patients with CD who are unaware of their diagnosis in both, rural and urban areas.

A refined genome phage display methodology delineates the human antibody response in patients with Chagas disease

Large-scale mapping of antigens and epitopes is pivotal for developing immunotherapies but challenging, especially for eukaryotic pathogens, owing to their large genomes. Here, we developed an integrated platform for genome phage display (gPhage) to show that unbiased libraries of the eukaryotic parasite Trypanosoma cruzi enable the identification of thousands of antigens recognized by serum samples from patients with Chagas disease. Because most of these antigens are hypothetical proteins, gPhage provides evidence of their expression during infection. We built and validated a comprehensive map of Chagas disease antibody response to show how linear and putative conformation epitopes, many rich in repetitive elements, allow the parasite to evade a buildup of neutralizing antibodies directed against protein domains that mediate infection pathogenesis. Thus, the gPhage platform is a reproducible and effective tool for rapid simultaneous identification of epitopes and antigens, not only in Chagas disease but perhaps also in globally emerging/reemerging acute pathogens.

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Genomic shotgun phage display (gPhage) of eukaryotes is feasible and promising.

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gPhage allows rapid antigen ID and epitope mapping, including 3D structures.

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Conformation epitopes can be identified and validated by using the gPhage platform.

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Most Chagas disease antigens are hypothetical proteins rich in repetitive elements.

Recombinogenic, genotoxic, and cytotoxic effects of azathioprine using in vivo assays

Azathioprine (Aza) is a purine antimetabolite immunosuppressant that is widely employed for immunosuppressive therapy in post-transplant recipients or patients with autoimmune diseases. Chronic use of immunosuppressants might produce several side effects, including a high rate of neoplasms in these patients. Considering that genotoxic effects are associated with an increased risk of developing cancer, the aim of this study was to examine the recombinogenic, genotoxic, and cytotoxic effects of Aza using Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster, as well as comet and micronucleus assays in mouse bone marrow cells. Further, the adverse effects of Aza were determined in mouse hepatic and renal tissues using histopathological analysis. Data demonstrated that Aza induced significant increased genotoxicity in D. melanogaster and mouse bone marrow cells at all concentrations tested. Homologous recombination was the predominant genotoxic event noted for the first time to be initiated by Aza in SMART. In histopathological analysis, Aza did not show any marked toxic activity in mouse hepatic and renal tissues. Therefore, the high rate of neoplasms reported in patients with long-term use of Aza may be attributed, at least partially, to the genotoxic action of this drug.

Gut Dysbiosis in Chagas Disease. A Possible Link to the Pathogenesis

Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi. Cardiomyopathy and damage to gastrointestinal tissue are the main disease manifestations. There are data suggesting that the immune response to T. cruzi depends on the intestinal microbiota. We hypothesized that Chagas disease is associated with an altered gut microbiome and that these changes are related to the disease phenotype. The stool microbiome from 104 individuals, 73 with Chagas disease (30 with the cardiac, 11 with the digestive, and 32 with the indeterminate form), and 31 healthy controls was characterized using 16S rRNA amplification and sequencing. The QIIME (Quantitative Insights Into Microbial Ecology) platform was used to analyze the data. Alpha and beta diversity indexes did not indicate differences between the groups. However, the relative abundance of Verrucomicrobia, represented primarily by the genus Akkermansia, was significantly lower in the Chagas disease groups, especially the cardiac group, compared to the controls. Furthermore, differences in the relative abundances of Alistipes, Bilophila, and Dialister were observed between the groups. We conclude that T. cruzi infection results in changes in the gut microbiome that may play a role in the myocardial and intestinal inflammation seen in Chagas disease.

ELISA Saliva for Trypanosoma cruzi Antibody Detection: An Alternative for Serological Surveys in Endemic Regions

Chagas is a neglected disease endemic in Latin America. Vector transmission control had been aggressively performed. Recent entomological surveillance in Brazil has revealed natural infection rates ranging from 0.40% to 0.52%. Although serological surveys are complex to develop, they are important for disease control. In this study, we validated the use of saliva in ELISA commercial kits with a cohort of 100 patients with Chagas disease followed at Hospital das Clinicas in São Paulo, Brazil, and 50 healthy controls. Five ELISA kits for detecting antibodies against Trypanosoma cruzi were tested. The best discrimination between Chagas patients and controls was observed with the Wiener kit, which yielded a sensitivity of 97% and a specificity of 100%. Our findings reveal that the use of saliva may be an alternative to large-scale screening surveys in detecting T. cruzi antibodies; it is a noninvasive sample collection method potentially key to large-scale screening in children.

Lack of evidence of seronegative infection in an endemic area of Chagas disease

The diagnosis of Chagas disease is based on the detection of Trypanosoma cruzi (T. cruzi)-specific antibodies. Nonetheless, there is concern about the sensitivity of current serological assays due to reports of T. cruzi PCR positivity among seronegative individuals. The aim of this study was to evaluate if T. cruzi seronegative infections occur in endemic areas. We recruited 2,157 individuals that were identified as having Chagas disease in a public health system database of an endemic region in Brazil. All participants were interviewed and 2,091 had a sample collected for serological and PCR testing. From these, 149 (7.1%) had negative serological results. PCR was positive in 610 samples (31.4%) of the 1,942 seropositive samples but in none of the 149 samples from seronegative participants. True T. cruzi seronegative infections seem to be rare (95% CI 0-3.7) and should not be a concern for blood supply, which relies on antibody screening.

An alternative storage method for characterization of the intestinal microbiota through next generation sequencing

Gut microbiota has been the subject of various molecular studies mainly due to its importance and wide-ranging relationships with human hosts. However, the storage of fecal samples prior to DNA extraction is critical when characterizing the composition of intestinal microbiota. Therefore, we aimed to understand the effects of different fecal storage methods to characterize intestinal microbiota using Next Generation Sequencing (NGS) as well as to establish an alternative conservation method of bacterial genetic material in these samples using guanidine. Stool samples from 10 healthy volunteers were collected. Each sample was divided into five aliquots: one aliquot was extracted immediately after collection (fresh) and two aliquots were subjected to freezing at -20 °C or -80 °C and extracted after 48 h. The other two aliquots were stored in guanidine at room temperature or 4 °C and extracted after 48 h. The V4 hypervariable regions of the bacterial and archeal 16S rRNA gene were amplified by PCR and sequenced using an Ion Torrent PGM platform for NGS. The data were analyzed using QIIME software. Statistical significance was determined using a non-parametric Kruskal-Wallis test. A total of 11,494,688 reads with acceptable quality were obtained. Unweighted principal coordinate analysis (PCoA) revealed that the samples were clustered based on the host rather than by the storage group. At the phylum and genus levels, we observed statistically significant differences between two genera, Proteobacteria (p=0.013) and Suterella (p=0.004), comparing frozen samples with guanidine-stored samples. Our data suggest that the use of guanidine can preserve bacterial genetic materials as well as freezing, providing additional conveniences.

Interleukin 10 (IL10) and transforming growth factor β1 (TGFβ1) gene polymorphisms in persistent IgE-mediated cow's milk allergy

OBJECTIVES

The aim of this cross-sectional study was to evaluate whether interleukin 10 (IL10) and transforming growth factor β1 (TGFβ1) gene polymorphisms were associated with persistent IgE-mediated cow's milk allergy in 50 Brazilian children. The diagnostic criteria were anaphylaxis triggered by cow's milk or a positive double-blind, placebo-controlled food challenge. Tolerance was defined as the absence of a clinical response to a double-blind, placebo-controlled food challenge or cow's milk exposure.

METHOD

The genomic DNA of the 50 patients and 224 healthy controls (HCs) was used to investigate five IL10 gene polymorphisms (-3575A/T, -2849A/G, -2763A/C, -1082G/A, -592C/A) and one TGFβ1 polymorphism (-509C/T).

RESULTS

Among the five IL10 polymorphisms analyzed, homozygosis for the G allele at the -1082 position was significantly higher in the patients compared with the healthy controls (p=0.027) and in the persistent cow's milk allergy group compared with the healthy controls (p=0.001).

CONCLUSIONS

Homozygosis for the G allele at the IL10 -1082G/A polymorphism is associated with the persistent form of cow's milk allergy.

Detection of Bartonella henselae DNA in clinical samples including peripheral blood of immune competent and immune compromised patients by three nested amplifications

Bacteria of the genus Bartonella are emerging pathogens detected in lymph node biopsies and aspirates probably caused by increased concentration of bacteria. Twenty-three samples of 18 patients with clinical, laboratory and/or epidemiological data suggesting bartonellosis were subjected to three nested amplifications targeting a fragment of the 60-kDa heat shock protein (HSP), the internal transcribed spacer 16S-23S rRNA (ITS) and the cell division (FtsZ) of Bartonella henselae, in order to improve detection in clinical samples. In the first amplification 01, 04 and 05 samples, were positive by HSP (4.3%), FtsZ (17.4%) and ITS (21.7%), respectively. After the second round six positive samples were identified by nested-HSP (26%), eight by nested-ITS (34.8%) and 18 by nested-FtsZ (78.2%), corresponding to 10 peripheral blood samples, five lymph node biopsies, two skin biopsies and one lymph node aspirate. The nested-FtsZ was more sensitive than nested-HSP and nested-ITS (p < 0.0001), enabling the detection of Bartonella henselae DNA in 15 of 18 patients (83.3%). In this study, three nested-PCR that should be specific for Bartonella henselae amplification were developed, but only the nested-FtsZ did not amplify DNA from Bartonella quintana. We conclude that nested amplifications increased detection of B. henselae DNA, and that the nested-FtsZ was the most sensitive and the only specific to B. henselae in different biological samples. As all samples detected by nested-HSP and nested-ITS, were also by nested-FtsZ, we infer that in our series infections were caused by Bartonella henselae. The high number of positive blood samples draws attention to the use of this biological material in the investigation of bartonellosis, regardless of the immune status of patients. This fact is important in the case of critically ill patients and young children to avoid more invasive procedures such as lymph nodes biopsies and aspirates.

Frequency of single nucleotide polymorphisms of some immune response genes in a population sample from São Paulo, Brazil

ABSTRACT Objective: To present the frequency of single nucleotide polymorphisms of a few immune response genes in a population sample from São Paulo City (SP), Brazil. Methods: Data on allele frequencies of known polymorphisms of innate and acquired immunity genes were presented, the majority with proven impact on gene function. Data were gathered from a sample of healthy individuals, non-HLA identical siblings of bone marrow transplant recipients from the Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, obtained between 1998 and 2005. The number of samples varied for each single nucleotide polymorphism analyzed by polymerase chain reaction followed by restriction enzyme cleavage. Results: Allele and genotype distribution of 41 different gene polymorphisms, mostly cytokines, but also including other immune response genes, were presented. Conclusion: We believe that the data presented here can be of great value for case-control studies, to define which polymorphisms are present in biologically relevant frequencies and to assess targets for therapeutic intervention in polygenic diseases with a component of immune and inflammatory responses.

Epstein-Barr virus nuclear antigen-2 detection and typing in immunocompromised children correlated with lymphoproliferative disorder biopsy findings

Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, plays a significant role as a cofactor in the process of tumorigenesis, and has consistently been associated with a variety of malignancies especially in immunocompromised patients. Forty-four children and adolescents (21 liver transplant patients, 7 heart transplant, 5 AIDS, 3 autoimmune hepatitis, 2 nephritic syndromes, 2 medullar aplasia, 2 primary immunodeficiency disorder patients, 1 thrombocytopenic purpura and 1 systemic lupus erythematosus) presenting with chronic active EBV infection (VCA-IgM persistently positive; VCA-IgG > 20 AU/mL and positive IgG _ EBNA) had peripheral blood samples obtained during clinically characterized EBV reactivation episodes. DNA samples were amplified in order to detect and type EBV on the basis of the EBNA-2 sequence (EBNA2 protein is essential for EBV-driven immortalization of B lymphocytes). Although we have found a predominance of type 1 EBNA-2 virus (33/44; 75%), 10 patients (22.73%) carried type 2 EBNA-2, and one liver transplant patient (2.27%) a mixture of the two types, the higher proportion of type 2 EBV, as well as the finding of one patient bearing the two types is in agreement with other reports held on lymphoproliferative disorder (LPD) patients, which analyzed tumor biopsies. We conclude that EBNA-2 detection and typing can be performed in peripheral blood samples, and the high prevalence of type 2 in our casuistic indicates that this population is actually at risk of developing LPD, and should be monitored.