Induction of CD4+CD25+FOXP3+ Regulatory T Cells during Human Hookworm Infection Modulates Antigen-Mediated Lymphocyte Proliferation

Hookworm infection is considered one of the most important poverty-promoting neglected tropical diseases, infecting 576 to 740 million people worldwide, especially in the tropics and subtropics. These blood-feeding nematodes have a remarkable ability to downmodulate the host immune response, protecting themselves from elimination and minimizing severe host pathology. While several mechanisms may be involved in the immunomodulation by parasitic infection, experimental evidences have pointed toward the possible involvement of regulatory T cells (Tregs) in downregulating effector T-cell responses upon chronic infection. However, the role of Tregs cells in human hookworm infection is still poorly understood and has not been addressed yet. In the current study we observed an augmentation of circulating CD4+CD25+FOXP3+ regulatory T cells in hookworm-infected individuals compared with healthy non-infected donors. We have also demonstrated that infected individuals present higher levels of circulating Treg cells expressing CTLA-4, GITR, IL-10, TGF-β and IL-17. Moreover, we showed that hookworm crude antigen stimulation reduces the number of CD4+CD25+FOXP3+ T regulatory cells co-expressing IL-17 in infected individuals. Finally, PBMCs from infected individuals pulsed with excreted/secreted products or hookworm crude antigens presented an impaired cellular proliferation, which was partially augmented by the depletion of Treg cells. Our results suggest that Treg cells may play an important role in hookworm-induced immunosuppression, contributing to the longevity of hookworm survival in infected people

Profile of Central and Effector Memory T Cells in the Progression of Chronic Human Chagas Disease

Chagas disease is a parasitic infection caused by protozoan Trypanosoma cruzi that affects approximately 11 million people in Latin America. The involvement of the host's immune response on the development of severe forms of Chagas disease has not been fully elucidated. Studies on the immune response against T. cruzi infection show that the immunoregulatory mechanisms are necessary to prevent the deleterious effect of excessive immune response stimulation and consequently the fatal outcome of the disease. A recall response against parasite antigens observed in in vitro peripheral blood cell culture clearly demonstrates that memory response is generated during infection. Memory T cells are heterogeneous and differ in both the ability to migrate and exert their effector function. This heterogeneity is reflected in the definition of central (TCM) and effector memory (TEM) T cells. Our results suggest that a balance between regulatory and effectors T cells may be important for the progression and development of the disease. Furthermore, the high percentage of central memory CD4+ T cells in indeterminate patients after stimulation suggests that these cells may modulate host's inflammatory response by controlling cell migration to tissues and their effector role during chronic phase of the disease

Identification of candidate antigens from adult stages of Toxocara canis for the serodiagnosis of human toxocariasis

In the present work, we identified adult Toxocara canis antigens through sodium dodecyl sulfate-polyacrylamide gel electrophoresis for potential use in human toxocariasis immunodiagnosis. The sensitivity and specificity of several semi-purified antigens, as well as their cross-reactivity with other parasitic infections, were assessed by IgM and IgG-enzime linked immunosorbent assay. Whilst we found that the crude extract of the parasite presented limited sensitivity, specificity and high cross-reactivity against other parasites, we identified 42, 58, 68 and 97-kDa semi-purified antigens as the most promising candidates for immunodiagnosis. Moreover, the 58 and 68-kDa antigens presented the lowest IgM cross-reactivity. When tested as a combination, a mixture of the 58 and 68-kDa antigens presented 100% sensitivity and specificity, as well as minor cross-reactivity. Although the combination of the 42, 58, 68 and 97-kDa antigens presented 100% sensitivity at a dilution of 1:40, the low specificity and high cross-reactivity observed suggested a limited use for diagnostic purposes. Our data suggested that the 58 and 68-kDa antigens might be most suitable for the immunodiagnosis of human toxocariasis

Clinical, biochemical and histological features related to treatment response and prognosis in autoimmune hepatitis

Introduction and Objectives: Autoimmune hepatitis (AIH) is a rare disease with a complex and not fully understood pathogenesis. Prognostic factors that might influence treatment response, relapse rates, and transplant-free survival are not well established. This study investigates clinical and biochemical markers associated with response to immunosuppression in patients with AIH. Materials and Methods: This retrospective cohort study included 102 patients with AIH treated with immunosuppressants and followed at the Federal University of Minas Gerais, Brazil, from 1990 to 2018. Pretreatment data such as clinical profiles, laboratory, and histological exams were analyzed regarding biochemical response at one year, histological remission, relapse, and death/transplantation rates. Results: Cirrhosis was present in 59 % of cases at diagnosis. One-year biochemical remission was observed in 55.7 % of the patients and was found to be a protective factor for liver transplant. Overall survival was 89 %. Patients with ascites at disease onset showed a higher aspartate aminotransferase (AST)/ alanine aminotransferase (ALT) ratio and elevated Model of end-stage liver disease (MELD) score. The presence of ascites was significantly associated with a 20-fold increase in mortality rate. Conclusions: AIH has a severe clinical phenotype in Brazilians, with high rates of cirrhosis and low remission rates. Early diagnosis and treatment are essential for achieving remission and reducing complications. The presence of ascites is significantly associated with mortality, emphasizing the importance of monitoring and prompt intervention. This study also stresses the need for further research on AIH in Latin America

Induction of CD4+CD25+FOXP3+ Regulatory T Cells during Human Hookworm Infection Modulates Antigen-Mediated Lymphocyte Proliferation.

Submitted by Nuzia Santos ([email protected]) on 2014-12-02T12:58:23Z No. of bitstreams: 1 Induction of CD4+CD25+FOXP3+ Regulatory T Cells during Human Hookworm Infection Modulates Antigen-Mediated Lymphocyte Proliferation.pdf: 583244 bytes, checksum: 380031abcfa9a222d6ee2c5e979d06ea (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2014-12-02T13:07:36Z (GMT) No. of bitstreams: 1 Induction of CD4+CD25+FOXP3+ Regulatory T Cells during Human Hookworm Infection Modulates Antigen-Mediated Lymphocyte Proliferation.pdf: 583244 bytes, checksum: 380031abcfa9a222d6ee2c5e979d06ea (MD5)Made available in DSpace on 2014-12-02T13:07:36Z (GMT). No. of bitstreams: 1 Induction of CD4+CD25+FOXP3+ Regulatory T Cells during Human Hookworm Infection Modulates Antigen-Mediated Lymphocyte Proliferation.pdf: 583244 bytes, checksum: 380031abcfa9a222d6ee2c5e979d06ea (MD5) Previous issue date: 2011Universidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/ Instituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. BrazilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/ Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunologia Celular e Molecular. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/ Universidade Federal de Minas Gerais. Hospital das Clínicas. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/ Instituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. BrazilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/ Instituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. BrazilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunologia Celular e Molecular. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, BrazilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunologia Celular e Molecular. Belo Horizonte, MG, BrasilInstituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. Brazil/Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunologia Celular e Molecular. Belo Horizonte, MG, BrasilInstituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. Brazil/Universidade Federal de Minas Gerais. Escola de Enfermagem. Belo Horizonte, MG, BrazilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, Brazil/Instituto Nacional de Ciencia e Tecnologia em Doenças Tropicais. Brazil/ Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunologia Celular e Molecular. Belo Horizonte, MG, BrasilUniversidade Federal de Minas Gerais. Departamento de Parasitologia. Belo Horizonte, MG, BrazilHookworm infection is considered one of the most important poverty-promoting neglected tropical diseases, infecting 576 to 740 million people worldwide, especially in the tropics and subtropics. These blood-feeding nematodes have a remarkable ability to downmodulate the host immune response, protecting themselves from elimination and minimizing severe host pathology. While several mechanisms may be involved in the immunomodulation by parasitic infection, experimental evidences have pointed toward the possible involvement of regulatory T cells (Tregs) in downregulating effector T-cell responses upon chronic infection. However, the role of Tregs cells in human hookworm infection is still poorly understood and has not been addressed yet. In the current study we observed an augmentation of circulating CD4+ CD25+ FOXP3+ regulatory T cells in hookworm-infected individuals compared with healthy non-infected donors. We have also demonstrated that infected individuals present higher levels of circulating Treg cells expressing CTLA-4, GITR, IL-10, TGF-b and IL-17. Moreover, we showed that hookworm crude antigen stimulation reduces the number of CD4+ CD25+ FOXP3+ T regulatory cells co-expressing IL-17 in infected individuals. Finally, PBMCs from infected individuals pulsed with excreted/secreted products or hookworm crude antigens presented an impaired cellular proliferation, which was partially augmented by the depletion of Treg cells. Our results suggest that Treg cells may play an important role in hookworm-induced immunosuppression, contributing to the longevity of hookworm survival in infected people

Risk factors for cancer in patients with primary biliary cholangitis and autoimmune hepatitis and primary biliary cholangitis overlap syndrome

Introduction and objectives: Primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) and PBC overlap syndrome (AIH/PBC) have been associated with a higher risk of hepatocellular carcinoma (HCC) and extra-hepatic malignancy (EHM). This study aims to assess potential risk factors associated with cancer development in PBC and AIH/PBC. Materials and methods: The Brazilian Cholestasis Study Group database was reviewed to compare clinical and laboratory features of PBC patients with HCC and EHM with those without cancer. Results: Among the 752 PBC patients enrolled, 64 of them with AIH/PBC, 87 cancers were identified in 72 patients, including 20 cases of HCC and 67 of EHM. Patients with HCC had a higher prevalence of cirrhosis (95% vs. 32.5% of those subjects without cancer, p≤0.001), smoking (55% vs. 12.3%, p≤0.001), CREST syndrome (30% vs 7.6%, p=0.003) and prior azathioprine (30% vs 8%, p= 0.005) and prednisone (35% vs 14%, p= 0.018) use, whereas patients with EHM had a higher prevalence of smoking (42.3% vs 12.4% of those subjects without cancer, p= <0.001), AMA positivity (96.6% vs 80.1%, p≤0.001), azathioprine therapy (21% vs 7.9%, p= 0.01) and concurrent other autoimmune diseases. In multivariate analysis, cirrhosis, obesity and prior azathioprine therapy were independent risk factors for HCC, while Sjogren syndrome and psoriasis were associated with EHM. Fibrates reduced EHM risk. Conclusions: The prevalence of EHM is higher when compared to HCC in PBC patients. Cirrhosis, obesity, prior azathioprine use, and concurrent autoimmune diseases were significantly associated with cancer in PBC

Clinical features and treatment outcomes of primary biliary cholangitis in a highly admixed population

Introduction and objectives: Little is known about primary biliary cholangitis (PBC) in non-whites. The purpose of this study was to evaluate clinical features and outcomes of PBC in a highly admixed population. Material and methods: The Brazilian Cholestasis Study Group multicentre database was reviewed to assess demographics, clinical features and treatment outcomes of Brazilian patients with PBC. Results: 562 patients (95% females, mean age 51 ± 11 years) with PBC were included. Concurrent autoimmune diseases and overlap with autoimmune hepatitis (AIH) occurred, respectively, in 18.9% and 14%. After a mean follow-up was 6.2 ± 5.3 years, 32% had cirrhosis, 7% underwent liver transplantation and 3% died of liver-related causes. 96% were treated with ursodeoxycholic acid (UDCA) and 12% required add-on therapy with fibrates, either bezafibrate, fenofibrate or ciprofibrate. Response to UDCA and to UDCA/fibrates therapy varied from 39%-67% and 42-61%, respectively, according to different validated criteria. Advanced histological stages and non-adherence to treatment were associated with primary non-response to UDCA, while lower baseline alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels correlated with better responses to both UDCA and UDCA/fibrates. Conclusions: Clinical features of PBC in highly admixed Brazilians were similar to those reported in Caucasians and Asians, but with inferior rates of overlap syndrome with AIH. Response to UDCA was lower than expected and inversely associated with histological stage and baseline AST and ALP levels. Most of patients benefited from add-on fibrates, including ciprofibrate. A huge heterogeneity in response to UDCA therapy according to available international criteria was observed and reinforces the need of global standardization