A complementary tool for management of disseminated Histoplasma capsulatum var. capsulatum infections in AIDS patients.

In South America, disseminated histoplasmosis due to Histoplasma capsulatum var. capsulatum (H. capsulatum), is a severe and frequent opportunistic infection in AIDS patients. In areas outside the USA where specific-Histoplasma antigen detection is not available, the diagnosis is difficult. With the galactomannan antigen (GM) detection, a test commonly used for invasive aspergillosis diagnosis, there is a cross-reactivity with H. capsulatum that can be helpful for the diagnosis of histoplasmosis. The aim of this study was to evaluate the GM detection for the diagnosis of disseminated histoplasmosis in AIDS patients. The performance of the GM detection was evaluated with serum collected in French Guiana where H. capsulatum is highly endemic. Sera from AIDS patients with disseminated histoplasmosis occurring from 2002 to 2009 and from control HIV-positive patients without histoplasmosis were tested with the GM detection and Histoplasma-specific antibody detection (IEP). In 39 AIDS patients with proven disseminated histoplasmosis, the sensitivity of the Histoplasma IEP was only 35.9% and was linked to the TCD4+ lymphocyte level. For the GM detection, the sensitivity (Se) was 76.9% and specificity (Sp) was 100% with the recommended threshold for aspergillosis diagnosis (0.5). The test was more efficient with a threshold of 0.4 (Se: 0.82 [95% CI: 0.66-0.92], Sp: 1.00 [95% CI: 0.86-1.00], LR+: >10, LR-: 0.18). This study confirms that the GM detection can be a surrogate marker for the diagnosis of disseminated histoplasmosis in AIDS patients in endemic areas where Histoplasma EIA is not available.

Long-term outcome of children with congenital toxoplasmosis.

OBJECTIVE: Maternal toxoplasmosis infection acquired during pregnancy carries significant risk of fetal damage. We aimed to assess the long-term outcome of children and young adults with congenital toxoplasmosis diagnosed and treated in utero. STUDY DESIGN: This was a 20 year prospective study (1985-2005). All mothers received spiramycin, alone or associated with pyrimethamine-sulfadoxine, and underwent amniocentesis and monthly ultrasound screening. Infected children were followed every 3-6 months. RESULTS: Of 666 liveborn children (676 mothers), 112 (17%) had congenital toxoplasmosis. Among these, 107 were followed up for 12-250 months: 79 were asymptomatic (74%) and 28 had chorioretinitis (26%). Only 1 child had a serious neurological involvement. CONCLUSION: The percentage of chorioretinitis in treated children depends on length of follow-up, but this complication occurs mainly before the age of 5 years and almost always before the age of 10 years. Visual impairment was infrequently severe, and outcome appears consistently good. Long-term follow-up is recommended to monitor ocular and neurological prognosis, whatever the practical difficulties.

FAN stimulates TNF(alpha)-induced gene expression, leukocyte recruitment, and humoral response.

Factor associated with neutral sphingomyelinase activation (FAN) is an adaptor protein that constitutively binds to TNF-R1. Microarray analysis was performed in fibroblasts derived from wild-type or FAN knockout mouse embryos to evaluate the role of FAN in TNF-induced gene expression. Approximately 70% of TNF-induced genes exhibited lower expression levels in FAN-deficient than in wild-type fibroblasts. Of particular interest, TNF-induced expression of cytokines/chemokines, such as IL-6 and CXCL-2, was impaired in FAN-deficient cells. This was confirmed by real time RT-PCR and ELISA. Upon i.p. TNF or thioglycollate injection, neutrophil recruitment into the peritoneal cavity was reduced by more than 50% in FAN-deficient mice. Nevertheless, FAN-deficient animals did not exhibit an increased susceptibility to different microorganisms including bacteria and parasites, indicating that FAN is not essential for pathogen clearance. Specific Ab response to BSA was substantially impaired in FAN-deficient mice and this was associated with a reduced content of leukocytes in the spleen of BSA-challenged FAN-deficient mice as compared with their wild-type counterparts. Altogether, our results indicate the involvement of FAN in TNF-induced gene expression and leukocyte recruitment, contributing to the establishment of the specific immune response.

Genotype of 88 Toxoplasma gondii isolates associated with toxoplasmosis in immunocompromised patients and correlation with clinical findings.

We report the genotyping analysis of Toxoplasma gondii isolates in samples collected from 88 immunocompromised patients, along with clinical and epidemiological data. Most of these samples were collected in France during the current decade by the Toxoplasma Biological Resource Center. Lack of specific anti-Toxoplasma treatment, pulmonary toxoplasmosis, and involvement of multiple organs were the 3 main risk factors associated with death for this patient group. Genotyping results with 6 microsatellite markers showed that type II isolates were predominant among patients who acquired toxoplasmic infection in Europe. Non-type II isolates included 13 different genotypes and were mainly collected from patients who acquired toxoplasmosis outside Europe. Type III was the second most common genotype recovered from patients, whereas type I was rare in our population. Three nonarchetypal genotypes were repeatedly recovered from different patients who acquired the infection in sub-Saharan Africa (genotypes Africa 1 and Africa 2) and in the French West Indies (genotype Caribbean 1). The distribution of genotypes (type II vs. non-type II) was not significantly different when patients were stratified by underlying cause of immunosuppression, site of infection, or outcome. We conclude that in immunocompromised patients, host factors are much more involved than parasite factors in patients' resistance or susceptibility to toxoplasmosis.

Unusual presentation of primary toxoplasmosis infection in a kidney-transplant patient complicated by an acute left-ventricular failure.

Although primary toxoplasmosis is a rare event following kidney transplantation, it can be life threatening. This report describes this complication. The patient presented with high-grade fever, haemolytic anaemia and haemophagocytic-syndrome-related pancytopaenia. Toxoplasma gondii diagnosis was ascertained by blood and bone-marrow PCR assays. After 6 weeks with Clindamycin plus pyrimethamine therapies and despite negativation of T. gondii blood PCR assay, the patient developed left-ventricular failure. After adding sulfamethoxazole/ trimethoprim, ramipril, digoxine, bisoprolol and spironolactone, he progressively recovered. Anti-T. gondii therapy was continued for 6 months. Four years later he received a third kidney allograft: at that time anti-T. gondii antibodies had become negative. The outcome was uneventful despite immunosuppression but with inclusion of sulfamethoxazole/trimethoprim prophylaxis. More than 3 years after the third kidney transplantation the patient has had no toxoplasmosis reactivation. This case report highlights that T. gondii can be the cause of myocarditis in a renal transplant recipient.

Genetic and epigenetic factors at COL2A1 and ABCA4 influence clinical outcome in congenital toxoplasmosis.

BACKGROUND: Primary Toxoplasma gondii infection during pregnancy can be transmitted to the fetus. At birth, infected infants may have intracranial calcification, hydrocephalus, and retinochoroiditis, and new ocular lesions can occur at any age after birth. Not all children who acquire infection in utero develop these clinical signs of disease. Whilst severity of disease is influenced by trimester in which infection is acquired by the mother, other factors including genetic predisposition may contribute. METHODS AND FINDINGS: In 457 mother-child pairs from Europe, and 149 child/parent trios from North America, we show that ocular and brain disease in congenital toxoplasmosis associate with polymorphisms in ABCA4 encoding ATP-binding cassette transporter, subfamily A, member 4. Polymorphisms at COL2A1 encoding type II collagen associate only with ocular disease. Both loci showed unusual inheritance patterns for the disease allele when comparing outcomes in heterozygous affected children with outcomes in affected children of heterozygous mothers. Modeling suggested either an effect of mother's genotype, or parent-of-origin effects. Experimental studies showed that both ABCA4 and COL2A1 show isoform-specific epigenetic modifications consistent with imprinting. CONCLUSIONS: These associations between clinical outcomes of congenital toxoplasmosis and polymorphisms at ABCA4 and COL2A1 provide novel insight into the molecular pathways that can be affected by congenital infection with this parasite.

IL-13 pre-treatment of murine peritoneal macrophages increases their anti-Toxoplasma gondii activity induced by lipopolysaccharides.

Th1 cytokines and microbial lipopolysaccharides (LPS) activate macrophages to produce inflammatory mediators and effector molecules. Althrough Th2 cytokines often have an opposite action to Th1 cytokines and down-modulate the inflammatory response of macrophages, they can induce a distinct alternative activation that is beneficial in host defence. In this study, we report that IL-13 enhances the anti-Toxoplasma activity of LPS-activated murine macrophages. The inhibition of parasite proliferation was not related to reduced Toxoplasma gondii penetration into the cells, nor to the conversion of tachyzoites into bradyzoites. Used alone, IL-13 triggers the polarisation of macrophages towards type 2. However, in LPS-activated macrophages, we show the priming capacity of this cytokine to enhance the expression of inducible nitric oxide synthase (iNOS), a major marker of type 1 macrophages. This effect of IL-13 was not dependent on the activation state of macrophages (resident versus thioglycolate-elicited) or the timing of pre-treatment. We demonstrate a correlation between the enhancement of NO production and upgrading of the microbicidal effectiveness of the macrophages. Thus, both Th2 and Th1 cytokines could activate macrophages to control infections.

Interleukin-13 primes iNO synthase expression induced by LPS in mouse peritoneal macrophages.

Th2 cytokines such as interleukin-13 (IL-13) have both, stimulatory and inhibitory effects on effector functions of macrophages. Reactive nitrogen species are classically induced in Th1 cytokines and/or lipopolysaccharides (LPS) activated macrophages and this response is inhibited by IL-13. In contrast, IL-13 primes macrophages to produce NO in response to LPS when IL-13 treatment happens prior to LPS exposure. This mechanism occurs through a complex signalling pathway, which involves the scavenger receptor CD36, the LPS receptor CD14 and the nuclear receptor PPARgamma. The enhancement of NO production is the consequence of iNOS induction at mRNA and protein levels. The increase of the NO production induced by LPS in IL-13 pre-treated macrophages is found to potentiate the inhibition of Toxoplasma gondii intracellular replication. These results reveal a novel IL-13 signalling pathway that primes the antimicrobial activity of macrophages induced by LPS caused by overexpression of the iNOS-NO axis.

Outcome for children infected with congenital toxoplasmosis in the first trimester and with normal ultrasound findings: a study of 36 cases.

OBJECTIVE: We wished to investigate the prognosis of children infected with Toxoplasma gondii during the first trimester of pregnancy and whose ultrasound findings were entirely normal, in order to find out whether congenital toxoplasmosis did or did not justify termination of pregnancy if there was no fetal abnormality on ultrasound. STUDY DESIGN: A prospective and retrospective study was carried out by 12 French centers who enrolled 36 children infected with T. gondii during the first trimester of pregnancy and whose ultrasound examinations showed no anomaly. The outcome of these children after the age of 12 months (mean 50 months, range 12-144 months) was analyzed. RESULTS: Of the 36 infected children, 28 (78%) presented subclinical toxoplasmosis. Only specific IgG antibodies persisted after 1 year. The principal manifestation in 7 children (19%) was chorioretinitis without major vision loss. Their intellectual development was entirely normal. One child (3%) developed severe congenital toxoplasmosis. CONCLUSION: Since 97% of children infected with toxoplasmosis during the first trimester of pregnancy are asymptomatic or only slightly affected, we believe that in such circumstances termination of pregnancy is not indicated. However, appropriate treatment is essential and prenatal ultrasound examinations should be free of any anomaly.

The rat Toxo1 locus directs toxoplasmosis outcome and controls parasite proliferation and spreading by macrophage-dependent mechanisms.

Toxoplasmosis is a healthcare problem in pregnant women and immunocompromised patients. Like humans, rats usually develop a subclinical chronic infection. LEW rats exhibit total resistance to Toxoplasma gondii infection, which is expressed in a dominant mode. A genome-wide search carried out in a cohort of F(2) progeny of susceptible BN and resistant LEW rats led to identify on chromosome 10 a major locus of control, which we called Toxo1. Using reciprocal BN and LEW lines congenic for chromosome 10 genomic regions from the other strain, Toxo1 was found to govern the issue of T. gondii infection whatever the remaining genome. Analyzes of rats characterized by genomic recombination within Toxo1, reduced the interval down to a 1.7-cM region syntenic to human 17p13. In vitro studies showed that the Toxo1-mediated refractoriness to T. gondii infection is associated with the ability of the macrophage to impede the proliferation of the parasite within the parasitophorous vacuole. In contrast, proliferation was observed in fibroblasts whatever the genomic origin of Toxo1. Furthermore, ex vivo studies indicate that macrophage controls parasitic infection spreading by a Toxo1-mediated mechanism. This forward genetics approach should ultimately unravel a major pathway of innate resistance to toxoplasmosis and possibly to other apicomplexan parasitic diseases.

Genotype of 86 Toxoplasma gondii isolates associated with human congenital toxoplasmosis, and correlation with clinical findings.

To study the influence of Toxoplasma gondii genotypes on the severity of human congenital toxoplasmosis (asymptomatic, benign, or severe infection or newborn or fetal death), 8 microsatellite markers were used to analyze 86 T. gondii isolates collected from patients with congenital toxoplasmosis. Seventy-four different genotypes were detected, some identical genotypes originating probably from the same source of contamination. The 3 less polymorphic microsatellite markers associated with 6 isoenzymatic markers allowed a classification of isolates into the 3 classical types and detected atypical genotypes. Whatever the clinical findings, type II isolates were largely predominant (84.88% in the whole collection and 96.49% in 57 consecutive cases). Type I and atypical isolates were not found in asymptomatic or benign congenital toxoplasmosis. However, in 4 cases in which children were not infected despite isolation of T. gondii from placenta, only type I isolates were found.