Preferential expression of domain cassettes 4, 8 and 13 of Plasmodium falciparum erythrocyte membrane protein 1 in severe malaria imported in France.

OBJECTIVES: Severe Plasmodium falciparum malaria (SM) involves cytoadhesion of parasitized red blood cells, mediated by P. falciparum erythrocyte membrane protein 1, which is encoded by var genes. Expression of var gene group A and B or encoding domain cassettes DC4, DC5, DC8 and DC13 has been implicated in SM in African children, but no data exist in the context of imported malaria. The aim of this study was to investigate var gene expression linked to clinical presentation and host factors in SM imported into France. METHODS: Expression level of var gene groups A, B, C, var1, var2csa, var3 and var genes encoding DC4, DC5, DC8 and DC13 was measured by quantitative RT-PCR and expressed in transcript units. Seventy SM and 48 uncomplicated malaria (UM) P. falciparum cases were analysed according to disease severity, epidemiological characteristics (migrants or travellers) and anti-P. falciparum antibodies. Cluster analysis was performed to identify gene expression profiles. RESULTS: Var1 and B/C expression were higher in UM than SM (0.66 (0-1.1) and 1.88 (1.3-2.4); p <0.04, respectively). Group C expression differed between migrants and travellers (0.21 (0-0.75) versus 0 (0-0); p 0.002). Group A differed in naive and pre-exposed patients (1.1 (0.7-1.5) versus 0.4 (0-1.1); p 0.01). Population clusters revealed increased expression from group A and B var genes, and DC4, DC8 and DC13 in SM. CONCLUSIONS: These results corroborate the implication of DC4, DC8 and DC13 in severe imported malaria cases as African children, and their expression depends of host factors.

Genome-wide association study of antibody responses to Plasmodium falciparum candidate vaccine antigens.

We conducted a genome-wide association study (GWAS) of antibody responses directed to three Plasmodium falciparum vaccine candidate antigens (MSP1, MSP2 and GLURP) previously associated with different patterns of protection against malaria infection in Senegalese children. A total of 174 950 single-nucleotide polymorphisms (SNPs) were tested for association with immunoglobulin G1 (IgG1) responses directed to MSP1 and to GLURP and with IgG3 responses to MSP2 FC27 and to MSP2 3D7. We first performed a single-trait analysis with each antibody response and then a multiple-trait analysis in which we analyzed simultaneously the three immune responses associated with the control of clinical malaria episodes. Suggestive associations (P<1 × 10(-4)) were observed for 25 SNPs in MSP1 antibody response analysis or in multiple-trait analysis. According to the strength of their observed associations and their functional role, the following genes are of particular interest: RASGRP3 (2p22.3, P=7.6 × 10(-6)), RIMS1 (6q13, P=2.0 × 10(-5)), MVB12B (9q33.3, P=8.9 × 10(-5)) and GNPTAB (12q23.2, P=7.4 × 10(-5)). Future studies will be required to replicate these findings in other African populations. This work will contribute to the elucidation of the host genetic factors underlying variable immune responses to P. falciparum.

Balancing immunity and tolerance: genetic footprint of natural selection in the transcriptional regulatory region of HLA-G.

Human leukocyte antigen-G (HLA-G) has well-recognized immunosuppressive properties modulating the activity of many immune system cells, and polymorphisms observed at the HLA-G 5' upstream regulatory region (5'URR) may influence gene transcriptional regulation. In this study, we characterized the sequence variation and haplotype structure of the HLA-G 5'URR in worldwide populations to investigate the evolutionary history of the HLA-G promoter and shed some light into the mechanisms that may underlie HLA-G expression control. A 1.4-kb region, encompassing the known HLA-G regulatory elements, was sequenced in three African populations from Senegal, Benin and Congo, and data were combined with those available in the literature, resulting in a total of 1411 individuals from 21 worldwide populations. High levels of nucleotide and haplotype diversities, excess of intermediate-frequency variants and reduced population differentiation were observed at this locus when compared with the background genomic variation. These features support a strong molecular signature of balancing selection at HLA-G 5'URR, probably as a result of the competing needs to maintain both a maternal-fetal immune tolerance and an efficient host immune response to invading pathogens during human evolution. An extended analysis of a 300-kb region surrounding HLA-G revealed that this region is not involved in a hitchhiking effect and may be the direct target of selection.

Worldwide genetic variation at the 3' untranslated region of the HLA-G gene: balancing selection influencing genetic diversity.

The HLA-G (human leukocyte antigen-G) molecule plays a pivotal role in immune tolerance by inhibiting different cell subsets involved in both innate and adaptive immunity. Besides its primary function in maintaining the maternal-fetal tolerance, HLA-G has been involved in a wide range of pathological conditions where it can be either favorable or detrimental to the patient, depending on the nature of the pathology. Although several studies have demonstrated the utmost importance of the 3' untranslated region (3'UTR) in the HLA-G expression profile, limited data exist on the sequence variability of this gene region in human populations. In this study, we characterized the genetic diversity and haplotype structure of the HLA-G 3'UTR by resequencing 444 individuals from three sub-Saharan African populations and retrieving data from the 1000 Genomes project and the literature. A total of 1936 individuals representing 21 worldwide populations were combined and jointly analyzed. Our data revealed a high level of nucleotide diversity, an excess of intermediate frequency variants and an extremely low population differentiation, strongly supporting a history of balancing selection at this locus. The 14-bp insertion/deletion polymorphism was further pointed out as the likely target of selection, emphasizing its potential role in the post-transcriptional regulation of HLA-G expression.

Association of HLA-G 3' untranslated region polymorphisms with antibody response against Plasmodium falciparum antigens: preliminary results.

Host and Plasmodium interactions result in highly variable clinical phenotypes, partly explained by the nature and level of anti-malarial antibody response. Human leukocyte antigen (HLA)-G can create a tolerogenic environment, allowing parasites to escape from anti-malarial immunity. We performed a family-based association study encompassing 483 Sereer individuals (261 children and their parents), and reported two independent signals at the HLA-G 3' untranslated region associated with antibody response to specific Plasmodium falciparum blood stage antigens, previously associated with malaria protection: (i) +3010G together with +3142C with total IgG and IgG1 against GLURP and (ii) +3196G with IgG3 against MSP2. While these results require further investigation, they suggest for the first time a role of HLA-G in the regulation of humoral immune response in malaria.

Schistosoma haematobium infection affects Plasmodium falciparum-specific IgG responses associated with protection against malaria.

We have previously shown that antibody responses directed to Plasmodium falciparum merozoite surface protein (MSP)-1, MSP-2 and glutamate-rich protein (GLURP) are associated with anti-malarial protection in residents of the Niakhar area of Senegal. In the same area, urinary schistosomiasis is frequent and we therefore assessed the possible influence of Schistosoma haematobium infection on these protective anti-malarial IgG responses. After adjustment for confounders, we found that the levels of IgG1 directed to MSP1 and GLURP were significantly lower in helminth carriers. The higher circulating levels of interleukin (IL)-10 present in the plasma of co-infected individuals were associated with decreased anti-plasmodial IgG responses, particularly of those directed to MSP-2. Our data thus reveal a modulation of P. falciparum-specific immune responses in the presence of a trematode helminth infection, potentially increasing infected individuals' risk of plasmodial infection or disease.

[Validation of the sentinel lymph node biopsy in breast cancer]. / Validation de la technique de biopsie du ganglion sentinelle dans le cancer du sein.

PURPOSE: Assessment of our experience and validation of the sentinel lymph node biopsy technique in breast cancer stage T0-T2N0M0 surgery. METHODS: Identification and biopsy of the sentinel lymph node by the radio colloid method in a consecutive series of 205 patients undergoing surgery for breast cancer stage T0-T2N0M0 between October 1998 and January 2007, initially in association with a complete axillary lymph node dissection (learning curve), later in an elective way. Prospective recording of the data and analysis with an average follow-up of 50 months (3 to 102 months). RESULTS: Biopsy rate of the sentinel lymph node of 90%, false negative rate of the method 2.5%, axillary recurrence rate 0%. CONCLUSION: We confirm in this series that the sentinel lymph node biopsy technique is a reliable approach in our experience for the evaluation of the axillary lymph node status in breast cancer stage T0-T2N0M0.

[Prolonged treatment with recombined growth hormone improves bone measures: study of body composition in 21 deficient adults on treatment]. / Le traitement prolongé par hormone de croissance recombinante améliore les paramètres osseux.

Adult growth hormone deficiency is characterized by changes in body composition: increase in total fat, decrease in lean mass and osteopenia, with a fall in Bone Mineral Content (BMC) and in Bone Mineral density (BMD) leading to a rise in risk of fracture. We have analyzed the changes in body composition in 21 adults treated from 9 to 78 months, by dual X-RAY absorptiometry (DEXA). We've demonstrated a gain in bone mass and density, particularly of axial skeleton; a latence of minimum 12 months has been necessary to objective these changes. The balance of fat and lean mass has been poorly modified by treatment except for the lean mass of the trunk, which is significantly increased. We think that the usual doses of rGH, based on IGF-1 level, are perhaps underestimated.

Evaluation of dual-energy X-ray absorptiometry for body-composition assessment in piglets and term human neonates.

The reproducibility, accuracy, and precision of dual-energy X-ray absorptiometry (DXA) was assessed by scanning 13 piglets (1471-5507 g) in triplicate. In four piglets, fat content was increased with porcine lard around the abdomen; additional measurements were performed on these animals. Reproducibility in DXA measurements from the animals without added fat was 0.09% for body weight, 1.95% for bone mineral content (BMC), and 5.35% for fat content. DXA estimates of body weight, BMC, and fat content were significantly correlated with scale body weight, ash weight, chemical calcium, and chemical fat. Body weight was measured accurately but fat content was overestimated by DXA. Mean BMC estimated by DXA represented 48% of ash weight and 215% of calcium content. The precision of DXA was 0.23% for body weight, 10.99% for ash weight, and 4.44% for calcium content. The precision of DXA for fat content was poor. However, for measurements performed in piglets with > 250 g fat, the precision was 8.85%. Thirty appropriate-forgestational-age term human neonates (birth weight: 3188 +/- 217 g) were scanned once during the first week of life. BMC and fat content were 54 +/- 6 and 470 +/- 92 g, respectively, which corresponded to 26.4 +/- 2.6 g calcium and 427 +/- 82 g fat. These were close to the reference values previously determined by chemical analysis. This study suggests that DXA is accurate and reliable for measurement of calcium and fat contents in human neonates. Further refinements would be beneficial for determining fat content in preterm human infants.

Increased parasellar activity on gallium SPECT is not specific for active cluster headache.

We have performed Gallium SPECT head scans in 30 successive cluster headache (CH) patients and in 7 migraineurs without aura. Parasellar hyperactivity was judged as present in 81% of chronic CH patients, 54% of episodic CH patients in an active period, 56% of episodic CH patients in remission and 71% of migraineurs. No significant correlations were found between the SPECT images and the duration of the disease, of cluster periods or of remissions. Increased parasellar activity on Gallium SPECT is thus not specific for CH, nor for the active period of episodic CH. The method lacks reliability for investigation of putative cavernous sinus inflammation.