Both C57BL/KsJ (H2d haplotype) and CB10-H2 (H2b haplotype) mice are highly susceptible to congenital toxoplasmosis.

Congenital toxoplasmosis may cause abortion, neonatal death, or foetal abnormalities. Despite little information from human studies, a genetic influence over congenital disease was demonstrated and, host genome have been implicated to resistance/susceptibility to Toxoplasma gondii infection in both human and mice. It was previously shown that BALB/c mice (H2d) were more resistant to congenital toxoplasmosis than C57BL/6 mice (H2b). However, it is unclear whether these differences are attributable to the MHC haplotype or to other components of the mouse's genetic background. Therefore, in this work, we intend to address this question by investigating the pregnancy outcome in H2d -congenic C57BL/6 mice (C57BL/KsJ-H2d) and H2b-congenic BALB/c mice (CB10-H2-H2b). For this, animals were infected by intragastric route on the first day of pregnancy and examined on days 8 (8dP/8dI) or 18 (18dP/18dI) of gestation and infection. The pregnancy outcome, parasite burden, systemic cytokine profile and antibody response to infection were evaluated. Infected mice showed adverse pregnancy outcomes, in parallel low parasite detection in the uterus/placenta, being that the C57BL/KsJ showed the worst results in relation to CB10-H2 mice. Both mouse lineages showed an increase in IFN-γ and TNF levels systemically on 8dP/8dI and on 18dP/18dI, and C57BL/KsJ showed an increase in IL-6 levels in both gestation/infection periods. Additionally, C57BL/KsJ showed 7- and 7-fold increase in IL-6, 4- and 2.5-fold increase in IFN-γ and, 6- and 4-fold increase in TNF production on 8dP/8dI and 18dP/18dI, respectively in association with 1.5-fold decrease in TGF-ß levels on 8dP/8dI compared to CB10-H2 mice. In conclusion, the high IFN-γ and TNF serum levels observed in C57BL/KsJ (H2d) and CB10-H2 (H2b) mice were involved in the poor pregnancy outcomes in congenital toxoplasmosis. In addition, the higher IFN-γ, IL-6 and TNF levels detected in C57BL/KsJ in relation to CB10-H2 mice on 8dP/8dI seem to be related to the genetic background of C57BL/6J mice that may have contributed to the worse pregnancy outcome in this mouse lineage.

TNFα rs1799964 TT genotype may be a susceptibility factor for vertical transmission of Toxoplasma gondii and clinical signs in newborns from pregnant women with acute toxoplasmosis.

BACKGROUND: One of the main impacts of Toxoplasma gondii infection occurs during pregnancy and is related to the vertical transmission of the parasite (congenital toxoplasmosis), which can cause severe clinical outcomes and fetal death. During acute infection, in order to control the rapid replication of tachyzoites, different host immune response genes are activated, and these include cytokine-encoding genes. Considering that polymorphisms in cytokine genes may increase susceptibility to vertical transmission of T. gondii by determining the immune status of the pregnant woman, this study evaluated the influence of polymorphisms of tumor necrosis factor alpha (TNFα) rs1799964 (- 1031) and interleukin 1 beta (IL1ß) rs16944 (- 511) genes on gestational toxoplasmosis and on the vertical transmission of the parasite and verified the allele and genotype frequency of these polymorphisms in pregnant patients whose respective newborn did or did not present clinical abnormalities suggestive of congenital toxoplasmosis. METHODS AND RESULTS: A total of 204 pregnant patients with (n = 114) or without (n = 90) infection by T. gondii were enrolled. No associations were found involving the polymorphisms rs1799964 (- 1031) of the TNFα gene and rs16944 (- 511) of the IL1ß gene with the increased chance of T. gondii infection during pregnancy. However, it was observed that the maternal TT genotype referring to the polymorphism of the TNFα gene seems to influence the vertical transmission of the parasite (P = 0.01; χ2 = 6.05) and the presence of clinical manifestation in newborns from pregnancies with acute toxoplasmosis (P = 0.007; χ2 = 9.68). CONCLUSION: The TNFα rs1799964 TT genotype may act as a susceptibility factor for the vertical transmission of parasite and for the presence of clinical signs in newborns from pregnant women with acute toxoplasmosis.

Disseminated and Congenital Toxoplasmosis in a Mother and Child With Activated PI3-Kinase δ Syndrome Type 2 (APDS2): Case Report and a Literature Review of Toxoplasma Infections in Primary Immunodeficiencies.

Phosphoinositide 3-kinase (PI3K) plays an integral role in lymphocyte function. Mutations in PIK3CD and PIK3R1, encoding the PI3K p110δ and p85α subunits, respectively, cause increased PI3K activity and result in immunodeficiency with immune dysregulation. We describe here the first cases of disseminated and congenital toxoplasmosis in a mother and child who share a pathogenic mutation in PIK3R1 and review the mechanisms underlying susceptibility to severe Toxoplasma gondii infection in activated PI3Kδ syndrome (APDS) and in other forms of primary immunodeficiency.

Contribution of IL6 -174 G>C and IL1B +3954 C>T polymorphisms to congenital infection with Toxoplasma gondii.

The purpose of this investigation was the determination of the distribution of genotypes and alleles, residing within interleukin 6 (IL6) and interleukin 1 (IL1) polymorphisms, among fetuses and neonates, congenitally infected with Toxoplasma gondii, and among uninfected control cases. The study included 22 fetuses and newborns infected with T. gondii and 49 control cases. Screening for IgG and IgM antibodies against the parasite and IgG avidity was performed by enzyme-linked fluorescent assay (ELFA) tests. Quantitation of T. gondii DNA in amniotic fluids was assayed by the real-time Q PCR technique for the parasitic B1 gene. Genotypes at IL6 and IL1 single nucleotide polymorphisms (SNPs) were determined by a self-designed, nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Representative genotypes at the studied loci were confirmed by sequencing. All the genotypes were estimated for Hardy-Weinberg equilibrium and IL1 genotypes were tested for linkage disequilibrium. Genotypes and haplotypes at the studied SNPs were investigated for their possible association with the occurrence of congenital T. gondii infection, using a logistic regression model. GC heterozygotes at the IL6 -174 G>C SNP were significantly associated with toxoplasmosis and increased the risk of T. gondii infection [odds ratio (OR) 4.24, 95 % confidence interval (CI) 1.24-14.50 in the codominant model, p ≤ 0.050]. In case of IL1 SNPs, similar prevalence rates were observed between T. gondii-infected and -uninfected offspring. Regarding allelic variability, the C alleles at both IL6 and IL1B SNPs were significantly more frequent in the infected than in the uninfected cases (p ≤ 0.050). It is concluded that IL6 -174 G>C and IL1B +3954 C>T SNPs might be involved in the development of congenital T. gondii infection.

ALOX12 in human toxoplasmosis.

ALOX12 is a gene encoding arachidonate 12-lipoxygenase (12-LOX), a member of a nonheme lipoxygenase family of dioxygenases. ALOX12 catalyzes the addition of oxygen to arachidonic acid, producing 12-hydroperoxyeicosatetraenoic acid (12-HPETE), which can be reduced to the eicosanoid 12-HETE (12-hydroxyeicosatetraenoic acid). 12-HETE acts in diverse cellular processes, including catecholamine synthesis, vasoconstriction, neuronal function, and inflammation. Consistent with effects on these fundamental mechanisms, allelic variants of ALOX12 are associated with diseases including schizophrenia, atherosclerosis, and cancers, but the mechanisms have not been defined. Toxoplasma gondii is an apicomplexan parasite that causes morbidity and mortality and stimulates an innate and adaptive immune inflammatory reaction. Recently, it has been shown that a gene region known as Toxo1 is critical for susceptibility or resistance to T. gondii infection in rats. An orthologous gene region with ALOX12 centromeric is also present in humans. Here we report that the human ALOX12 gene has susceptibility alleles for human congenital toxoplasmosis (rs6502997 [P, <0.000309], rs312462 [P, <0.028499], rs6502998 [P, <0.029794], and rs434473 [P, <0.038516]). A human monocytic cell line was genetically engineered using lentivirus RNA interference to knock down ALOX12. In ALOX12 knockdown cells, ALOX12 RNA expression decreased and levels of the ALOX12 substrate, arachidonic acid, increased. ALOX12 knockdown attenuated the progression of T. gondii infection and resulted in greater parasite burdens but decreased consequent late cell death of the human monocytic cell line. These findings suggest that ALOX12 influences host responses to T. gondii infection in human cells. ALOX12 has been shown in other studies to be important in numerous diseases. Here we demonstrate the critical role ALOX12 plays in T. gondii infection in humans.

Impaired innate immunity in mice deficient in interleukin-1 receptor-associated kinase 4 leads to defective type 1 T cell responses, B cell expansion, and enhanced susceptibility to infection with Toxoplasma gondii.

Interleukin-1 receptor (IL1R)-associated kinase 4 (IRAK4) is a member of the IRAK family and has an important role in inducing the production of inflammatory mediators. This kinase is downstream of MyD88, an adaptor protein essential for Toll-like receptor (TLR) function. We investigated the role of this kinase in IRAK4-deficient mice orally infected with the cystogenic ME49 strain of Toxoplasma gondii. IRAK4(-/-) mice displayed higher morbidity, tissue parasitism, and accelerated mortality than the control mice. The lymphoid follicles and germinal centers from infected IRAK4(-/-) mice were significantly smaller. We consistently found that IRAK4(-/-) mice showed a defect in splenic B cell activation and expansion as well as diminished production of gamma interferon (IFN-γ) by T lymphocytes. The myeloid compartment was also affected. Both the frequency and ability of dendritic cells (DCs) and monocytes/macrophages to produce IL-12 were significantly decreased, and resistance to infection with Toxoplasma was rescued by treating IRAK4(-/-) mice with recombinant IL-12 (rIL-12). Additionally, we report the association of IRAK4 haplotype-tagging single nucleotide polymorphisms (tag-SNPs) with congenital toxoplasmosis in infected individuals (rs1461567 and rs4251513, P < 0.023 and P < 0.045, respectively). Thus, signaling via IRAK4 is essential for the activation of innate immune cells, development of parasite-specific acquired immunity, and host resistance to infection with T. gondii.

Host genetic and epigenetic factors in toxoplasmosis

Analysing human genetic variation provides a powerful tool in understanding risk factors for disease. Toxoplasma gondii acquired by the mother can be transmitted to the fetus. Infants with the most severe clinical signs in brain and eye are those infected early in pregnancy when fetal immunity is least well developed. Genetic analysis could provide unique insight into events in utero that are otherwise difficult to determine. We tested the hypothesis that propensity for T. gondii to cause eye disease is associated with genes previously implicated in congenital or juvenile onset ocular disease. Using mother-child pairs from Europe (EMSCOT) and child/parent trios from North America (NCCCTS), we demonstrated that ocular and brain disease in congenital toxoplasmosis associate with polymorphisms in ABCA4 encoding ATP-binding cassette transporter, subfamily A, member 4 previously associated with juvenile onset retinal dystrophies including Stargardt's disease. Polymorphisms at COL2A1 encoding type II collagen, previously associated with Stickler syndrome, associated only with ocular disease in congenital toxoplasmosis. Experimental studies showed that both ABCA4 and COL2A1 show isoform-specific epigenetic modifications consistent with imprinting, which provided an explanation for the patterns of inheritance observed. These genetic and epigenetic risk factors provide unique insight into molecular pathways in the pathogenesis of disease.

Inmunodiagnostico de la toxoplasmosis: hemaglutinación indirecta e inmunoanalisis enzimatico IgM e IgG / Immunodiagnosis of the toxoplasmosis: indirect hemagglutination IgM and IgG enzime linked immunosorbent assay

En el presente trabajo se compararon los métodos de Hemaglutinación Indirecta (HAI) e Inmunoanálisis Enzimático (ELISA, IgM e IgG) para investigar anticuerpos antitoxoplasma en 54 muestras sanguíneas. Los resultados obtenidos muestran una concordancia del 62.96 por ciento entre HAI y ELISA. IgM y del 83.33 por ciento entre HAI y ELISA. IgG. El análisis estadístico mediante el chi cuadrado, reveló que hubo significancia cuando se compararon todos los títulos de HAI a partir de 1:2 con todos los índices de ELISA. IgM, esta significancia no puede establecer la superioridad de un método sobre el otro, debido: a. La utilización del "kit" comercial ELISA. IgM que solo detecta este tipo de anticuerpo; b. La detección por HAI de IgM e IgG; c. La presencia de anticuerpos inespecíficos de HAI y ELISA. IgG reveló que no hubo diferencias, lo cual nos indica que la discordancia entre ambos métodos no es estadísticamente significante