Publications by authors named "Ibrahim Sadissou"

Article Synopsis
  • The study investigates the presence of African trypanosomes in the skin of individuals at risk for gambiense Human African Trypanosomiasis (gHAT) in Guinea, finding that a significant number of seropositive individuals carry the parasites in their dermal layers.
  • Out of nearly 19,000 screened participants, 96 were included, revealing dermatological symptoms to be more common in seropositive individuals compared to seronegative ones.
  • Follow-up showed a decrease in skin parasite detection post-treatment, but a notable percentage of untreated seropositive individuals continued to test positive, highlighting potential challenges in achieving gHAT elimination.
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Background: Placental malaria (PM) is associated with a higher susceptibility of infants to malaria. A hypothesis of immune tolerance has been suggested but no clear explanation has been provided so far. Our goal was to investigate the involvement of inhibitory receptors LILRB1 and LILRB2, known to drive immune evasion upon ligation with pathogen and/or host ligands, in PM-induced immune tolerance.

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Introduction: Non-classical class I human leukocyte antigens (HLA) molecules are known to modulate the function of cytotoxic cells (NK and T CD8+) during viral infection by interacting with inhibitory/activating receptors. However, little is known about the HLA-E/-F genetic variability on arbovirus infections.

Methods: We evaluated by massive parallel sequencing the full HLA-E/-F genetic diversity among patients infected during the arbovirus (ZIKV, DENV, and CHIKV) outbreak leading to a broad range of neurological complications in the Brazilian State of Pernambuco.

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Background: Little attention has been devoted to the role of the immunoregulatory HLA-E/-F/-G genes in malaria. We evaluated the entire HLA-E/-F/-G variability in Beninese children highly exposed to Plasmodium falciparum (P.f.

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Severe neurological complications following arbovirus infections have been a major concern in seasonal outbreaks, as reported in the Northeast region of Brazil, where the same mosquito transmitted Zika (ZIKV), Dengue (DENV), and Chikungunya (CHIKV) viruses. In this study, we evaluated the levels of 36 soluble markers, including cytokines, chemokines, growth factors, and soluble HLA-G (Luminex and ELISA) in: i) serum and cerebrospinal fluid (CSF), during the acute phase and two years after the infection (recovery phase, only serum), ii) the relationship among all soluble molecules in serum and CSF, and iii) serum of infected patients without neurological complications, during the acute infection. Ten markers (sHLA-G, IL-10, IL-22, IL-8, MIP-1α, MIP-1β, MCP-1, HGF, VEGF, and IL-1RA) exhibited differential levels between the acute and recovery phases, with pronounced increases in MIP-1α (<0.

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Background: Since HLA-G is an immune checkpoint molecule and since Crohn's disease (CD) and ulcerative colitis (UC) exhibit deregulated immune-mediated mechanisms, we aimed to evaluate intestinal HLA-G expression and soluble HLA-G (sHLA-G) levels in CD/UC patients stratified according to the CD phenotype/localization and UC extension.

Methods: HLA-G tissue expression was assessed by immunohistochemistry in biopsies collected from 151 patients (90 CD, 61 UC) and in surgical resection specimens (28 CD, 12 UC). Surgical material from 24 healthy controls was also assessed.

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Human leukocyte antigen-C (HLA-C) is a classical HLA class I molecule that binds and presents peptides to cytotoxic T lymphocytes in the cell surface. HLA-C has a dual function because it also interacts with Killer-cell immunoglobulin-like receptors (KIR) receptors expressed in natural killer and T cells, modulating their activity. The structure and diversity of the HLA-C regulatory regions, as well as the relationship among variants along the HLA-C locus, are poorly addressed, and few population-based studies explored the HLA-C variability in the entire gene in different population samples.

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Background: The diagnosis of gambiense human African trypanosomiasis (gHAT) typically involves 2 steps: a serological screen, followed by the detection of living trypanosome parasites in the blood or lymph node aspirate. Live parasites can, however, remain undetected in some seropositive individuals, who, we hypothesize, are infected with Trypanosoma brucei gambiense parasites in their extravascular dermis.

Methods: To test this hypothesis, we conducted a prospective observational cohort study in the gHAT focus of Forecariah, Republic of Guinea.

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The aim of this study was to evaluate the expression of human leukocyte antigen G (HLA-G) in leprosy. Biopsy and serum samples were collected from 18 patients presenting with leprosy and from healthy controls. Samples were analyzed using immunohistochemistry and ELISA techniques.

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Background: Increasing evidence shows that chronic inflammation plays an important role in thyroid tumorigenesis. Cytokines as central mediators in inflammatory microenvironment can present both pro-tumour and anti-tumour effects and cytokine release may be influenced by soluble HLA-G (sHLA-G), an immune checkpoint molecule whose expression can also be induced by certain cytokines.

Aim: To understand the role of these soluble factors in papillary thyroid cancer (PTC).

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Human Leukocyte Antigen-G (HLA-G) is a non-classical class I molecule that is involved in maternal-fetal immunotolerance. In cancer, this molecule contributes to the tumor escape. The aim of this study was to evaluate the 14 bp and +3142  polymorphisms of the 3' UTR and its relation with plasma and tissue HLA-G expression in patients with grade IV (high-grade) and grade I/II (low-grade) gliomas and controls.

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Article Synopsis
  • Recent research has shifted focus from severe malaria to studying genetic variants linked to non-severe malaria and innate immunity mechanisms.
  • A genome-wide association study (GWAS) was conducted on two infant cohorts in southern Benin to identify genes connected to mild malaria attacks and overall malaria infections.
  • Key findings point to significant roles for genes like PTPRT and MYLK4 in providing protection against malaria, demonstrating the potential of GWAS to reveal new candidate genes that inform how the body naturally resists malaria.
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Placental malaria has been associated with an immune tolerance phenomenon and a higher susceptibility to malaria infection during infancy. HLA-G is involved in fetal maternal immune tolerance by inhibiting maternal immunity. During infections HLA-G can be involved in immune escape of pathogens by creating a tolerogenic environment.

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Background: Substantial evidence indicates that cytophilic IgG responses to Plasmodium falciparum merozoite antigens play a role in protection from malaria. The specific targets mediating immunity remain unclear. Evaluating antibody responses in infants naturally-exposed to malaria will allow to better understand the establishment of anti-malarial immunity and to contribute to a vaccine development by identifying the most appropriate merozoite candidate antigens.

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Article Synopsis
  • HLA-G is important for immune tolerance, and pathogens can increase soluble HLA-G (sHLA-G) to help evade the immune response, but its relationship with geohelminth infections has not been studied before.
  • This study in Southeastern Benin involved 400 pregnant women, where stool and blood samples were collected to assess helminth infections and sHLA-G levels, using the Kato-Katz technique for diagnosis and quantile regression for analysis.
  • Results showed that sHLA-G levels rose during pregnancy, peaking at delivery, and hookworm infection was linked to higher sHLA-G levels in women above the 80th percentile, suggesting a role for s
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The HLA-G and MICA genes are stimulated under inflammatory conditions and code for soluble (sMICA and sHLA-G) or membrane-bound molecules that exhibit immunomodulatory properties. It is still unclear whether they would have a synergistic or antagonistic effect on the immunomodulation of the inflammatory response, such as in chronic kidney disease (CKD), contributing to a better prognosis after the kidney transplantation. In this study, we went from genetic to plasma analysis, first evaluating the polymorphism of MICA, NKG2D and HLA-G in a cohort from Southern Brazil, subdivided in a control group of individuals (n = 75), patients with CKD (n = 94), and kidney-transplant (KT) patients (n = 64).

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HLA-G/E/F genes exhibit immunomodulatory properties and are expressed in placenta. Little attention has been devoted to the study of these genes in sub-Saharan African populations, which are yet the most diverse. To fill this gap, we evaluated the complete gene variability, approximately 5.

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Article Synopsis
  • Maternal IgG, specifically the IgG3 subclass, plays a critical role in providing immunity against malaria to infants via transplacental transfer, influenced by the binding ability to the neonatal Fc receptor (FcRn).
  • The study involved 497 mother-infant pairs from Benin to assess the levels of malaria-specific IgG antibodies and the presence of the IgG3-H435 polymorphism, which may enhance antibody transfer and longevity in infants.
  • Initial findings indicate that the IgG3-H435 variant is present in about 24% of mothers in malaria-endemic areas, suggesting a potential link between this variant and improved malaria protection for infants during early life.
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Article Synopsis
  • HLA-G is a molecule that helps the body tolerate the presence of the fetus during pregnancy, and its levels can be affected by infections like malaria.
  • A study in Benin found that the levels of soluble HLA-G (sHLA-G) increase significantly at delivery, and this increase is tied to factors such as maternal malaria and low birth weight.
  • Researchers followed 400 pregnant women and their babies over two years, discovering that higher sHLA-G levels were linked to malaria infections in children and that sHLA-G levels in infants were related to the mother's levels during pregnancy.
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To our knowledge, effects of age, placental malaria infection, infections during follow-up, nutritional habits, sickle-cell trait and individual exposure to Anopheles bites were never explored together in a study focusing on the acquisition of malaria antibody responses among infants living in endemic areas.Five hundred and sixty-seven Beninese infants were weekly followed-up from birth to 18 months of age. Immunoglobulin G (IgG), IgG1 and IgG3 specific for 5 malaria antigens were measured every 3 months.

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In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model's parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data.

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Antibodies that impede the invasion of Plasmodium falciparum (P. falciparum) merozoites into erythrocytes play a critical role in anti-malarial immunity. The Growth Inhibition Assay (GIA) is an in vitro measure of the functional capacity of such antibodies to limit erythrocyte invasion and/or parasite growth.

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Background: HLA-G, a non-classical HLA class I antigen, is of crucial interest during pregnancy by inhibiting maternal immune response. Its role during infections is discussed, and it has been described that high levels of soluble HLA-G during childhood increase the risk of malaria. To explore more precisely interactions between soluble HLA-G and malaria, latent class analysis was used to test whether distinct sub-populations of children, each with distinctive soluble HLA-G evolutions may suggest the existence of groups presenting variable malaria susceptibility.

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Background: The immunosuppressive properties of HLA-G protein can create a tolerogenic environment that may allow Plasmodium falciparum to avoid host immune responses. There are known associations between high levels of circulating soluble HLA-G (sHLA-G) and either parasite or viral infections and it has been suggested that the induction of sHLA-G expression could be a mechanism via which infectious agents subvert host immune defence. The study presented here is the first to investigate the possible association between sHLA-G and malaria or malaria related risk factors in Benin.

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