High neuroticism and low conscientiousness are associated with interleukin-6.

BACKGROUND: High Neuroticism and low Conscientiousness are frequently implicated in health-risk behaviors, such as smoking and overeating, as well as health outcomes, including mortality. Their associations with physiological markers of morbidity and mortality, such as inflammation, are less well documented. The present research examines the association between the five major dimensions of personality and interleukin-6 (IL-6), a pro-inflammatory cytokine often elevated in patients with chronic morbidity and frailty. METHOD: A population-based sample (n=4923) from four towns in Sardinia, Italy, had their levels of IL-6 measured and completed a comprehensive personality questionnaire, the NEO-PI-R. Analyses controlled for factors known to have an effect on IL-6: age; sex; smoking; weight; aspirin use; disease burden. RESULTS: High Neuroticism and low Conscientiousness were both associated with higher levels of IL-6. The findings remained significant after controlling for the relevant covariates. Similar results were found for C-reactive protein, a related marker of chronic inflammation. Further, smoking and weight partially mediated the association between impulsivity-related traits and higher IL-6 levels. Finally, logistic regressions revealed that participants either in the top 10% of the distribution of Neuroticism or the bottom 10% of conscientiousness had an approximately 40% greater risk of exceeding clinically relevant thresholds of IL-6. CONCLUSIONS: Consistent with the literature on personality and self-reported health, individuals high on Neuroticism or low on Conscientiousness show elevated levels of this inflammatory cytokine. Identifying critical medical biomarkers associated with personality may help to elucidate the physiological mechanisms responsible for the observed connections between personality traits and physical health.

Drosophila immune deficiency (IMD) is a death domain protein that activates antibacterial defense and can promote apoptosis.

We report the molecular characterization of the immune deficiency (imd) gene, which controls antibacterial defense in Drosophila. imd encodes a protein with a death domain similar to that of mammalian RIP (receptor interacting protein), a protein that plays a role in both NF-kappaB activation and apoptosis. We show that imd functions upstream of the DmIKK signalosome and the caspase DREDD in the control of antibacterial peptide genes. Strikingly, overexpression of imd leads to constitutive transcription of these genes and to apoptosis, and both effects are blocked by coexpression of the caspase inhibitor P35. We also show that imd is involved in the apoptotic response to UV irradiation. These data raise the possibility that antibacterial response and apoptosis share common control elements in Drosophila.

A prime-boost immunisation regimen using DNA followed by recombinant modified vaccinia virus Ankara induces strong cellular immune responses against the Plasmodium falciparum TRAP antigen in chimpanzees.

Two chimpanzees were vaccinated intramuscularly against malaria using plasmid DNA expressing the pre-erythrocytic antigens thrombospondin related adhesion protein (PfTRAP) and liver stage specific antigen-1 (PfLSA-1) of Plasmodium falciparum together with GM-CSF protein. A recombinant modified vaccinia virus Ankara (MVA) expressing PfTRAP was injected intramuscularly 6 weeks later to boost the immune response. This sequence of antigen delivery induced a specific and long-lasting T cell and antibody response to PfTRAP as detected by ELISPOT assay and ELISA. Antibody responses were detected after four DNA injections, and were boosted by injection of recombinant MVA expressing PfTRAP. Interferon-gamma secreting antigen-specific T cells were detected in both animals, but only after boosting with recombinant MVA. By screening a panel of PfTRAP-derived peptides, an epitope was identified that was recognized by cytotoxic T lymphocytes in one of the chimpanzees studied. T cells specific for this epitope were present in PBMCs and liver-infiltrating lymphocytes at a frequency of between 1 in 200 and 1 in 500. The high immunogenicity of this prime-boost regimen in chimpanzees supports further assessment of this delivery strategy for the induction of protection against P. falciparum malaria in humans.

The A-domain and the thrombospondin-related motif of Plasmodium falciparum TRAP are implicated in the invasion process of mosquito salivary glands.

Sporozoites from all Plasmodium species analysed so far express the thrombospondin-related adhesive protein (TRAP), which contains two distinct adhesive domains. These domains share sequence and structural homology with von Willebrand factor type A-domain and the type I repeat of human thrombospondin (TSP). Increasing experimental evidence indicates that the adhesive domains bind to vertebrate host ligands and that TRAP is involved, through an as yet unknown mechanism, in the process of sporozoite motility and invasion of both mosquito salivary gland and host hepatocytes. We have generated transgenic P.berghei parasites in which the endogenous TRAP gene has been replaced by either P.falciparum TRAP (PfTRAP) or mutated versions of PfTRAP carrying amino acid substitutions or deletions in the adhesive domains. Plasmodium berghei sporozoites carrying the PfTRAP gene develop normally, are motile, invade mosquito salivary glands and infect the vertebrate host. A substitution in a conserved residue of the A-domain or a deletion in the TSP motif of PfTRAP impairs the sporozoites' ability to invade mosquito salivary glands. Notably, midgut sporozoites from these transgenic parasites are still able to infect mice. Midgut sporozoites carrying a mutation in the A-domain of PfTRAP are motile, while no gliding motility could be detected in sporozoites with a TSP motif deletion.

Transformed Toxoplasma gondii tachyzoites expressing the circumsporozoite protein of Plasmodium knowlesi elicit a specific immune response in rhesus monkeys.

Toxoplasma gondii tachyzoites were transformed with the coding sequence of the circumsporozoite (CS) protein of the primate malaria parasite Plasmodium knowlesi. A single inoculation of live transformed tachyzoites elicited an antibody response directed against the immunodominant repeat epitope (EQPAAGAGG)2 of the P. knowlesi CS protein in rhesus monkeys. Notably, these animals failed to show a positive serum conversion against T. gondii. Antibodies against Toxoplasma antigens were detected only after a second inoculation with a higher number of transformed tachyzoites. This boost induced an increased antibody response against the P. knowlesi CS protein associated with immunoglobulin class switching, thus demonstrating the establishment of immunological memory. These results indicate that the Toxoplasma-derived CS protein is efficiently recognized by the monkey immune system and represents an immunodominant antigen in transformed parasites.

Thrombospondin related adhesive protein (TRAP), a potential malaria vaccine candidate.

We have investigated whether naturally induced immunity to Plasmodium falciparum thrombospondin related adhesive protein contributes to protection against malaria in humans. We have carried out a case control study in children living in an endemic region of West Africa to reveal associations between PfTRAP seroprevalence and the risk of cerebral malaria. Sera collected from the case and control groups were analysed by ELISA to compare their serum reactivity against PfTRAP, the circumsporozoite protein and the merozoite surface protein 1. Children with uncomplicated malaria had a significantly higher PfTRAP seroprevalence when compared to children with cerebral malaria. The risk of developing cerebral malaria appeared to depend on the reciprocal relationship between sporozoite inoculation rates and humoral immunity against PfTRAP. Our results suggest that naturally induced humoral immunity against PfTRAP contributes to the development of protection against severe malaria. Experimentally induced immunity against TRAP in different rodent models has consistently proven to elicit a high degree of protection against malaria. This together with the functional properties of TRAP and data describing CD4 and CD8 epitopes for PfTRAP indicate that this molecule could increase the protective efficiency of available sporozoite malaria vaccines.

Molecular cloning and expression analysis of a Cryptosporidium parvum gene encoding a new member of the thrombospondin family.

The apicomplexan parasite Cryptosporidium parvum invades and multiplies primarily in the brush border cells of the intestinal mucosa causing in AIDS patients a severe diarrhoea that represents a significant contributing factor leading to death. Morphological analysis indicates that the invasion machinery of C. parvum is similar to the apical complex of other parasites of the phylum Apicomplexa. We provide here evidence indicating that C. parvum also shares with these parasites a molecule crucial for the invasion of host cells. We have cloned a 3894 bp-long C. parvum cDNA encoding a protein characterised by sequence and structural similarities with members of the thrombospondin (TSP) family previously described in apicomplexan parasites of the genera Toxoplasma, Eimeria and Plasmodium. This novel C. partum molecule, the TSP-related adhesive protein of Cryptosporidium-1 (TRAP-C1), is encoded by a single copy gene containing no introns. TRAP-C1 is localised in the apical end of C. parvum sporozoites and is structurally related to the micronemal proteins MIC2 of Toxoplasma and Etp100 of Eimeria, which are involved in host-cell attachment and/or invasion. The identification of TRAP-C1 sheds new light on the molecules possibly involved in the invasion process of intestinal cells by C. parvum. We have also analysed the sequence variation of TRAP-C1 among C. parvum isolates and in the closely related species C. wrairi.

The Thrombospondin-related Protein Family of Apicomplexan Parasites: The Gears of the Cell Invasion Machinery.

A number of severe diseases of medical and veterinary importance are caused by parasites of the phylum Apicomplexa. These parasites invade host cells using similar subcellular structures, organelles and molecular species. Proteins containing one or more copies of the type I repeat of human platelet thrombospondin (TSP1), are crucial components of both locomotion and invasion machinery. Members of this family have been identified in Eimeria tenella, E. maxima, Toxoplasma gondii, Cryptosporidium parvum and in all Plasmodium species so far analysed. Here, Andrea Crisanti and colleagues discuss the structure, localization and current understanding of the function of TSP family members in the invasion of target cells by apicomplexan parasites.

Cloning and expression of the thrombospondin related adhesive protein gene of Plasmodium berghei.

Sporozoite recognition of host cells is a key step in the life-cycle of malaria parasites. Two sporozoite proteins have so far been characterized in some detail, the circumsporozoite protein (CS) and thrombospondin related adhesive protein (TRAP). We report here the cloning and expression of the TRAP gene homologue from Plasmodium berghei, PbTRAP. The PbTRAP gene encodes a protein of 606 amino acids having a deduced molecular mass of 66 kDa. The overall structure is clearly that of the TRAP family having a signal sequence followed by an integrin A domain, a sulphatide binding motif, followed by a proline based repeat before a transmembrane domain and helical cytoplasmic tail. The observed molecular mass is almost 50% larger than expected, this can be explained almost entirely by the abnormal behaviour in SDS-PAGE of the proline based repeat. As would be expected PbTRAP shows greatest similarity with the P. yoelli TRAP homologue sporozoite surface protein 2 (SSP2) than with PfTRAP, the TRAP gene from P. falciparum. The pattern of expression is similar to that of SSP2.

H-NS regulation of virulence gene expression in enteroinvasive Escherichia coli harboring the virulence plasmid integrated into the host chromosome.

We have previously shown that integration of the virulence plasmid pINV into the chromosome of enteroinvasive Escherichia coli and of Shigella flexneri makes these strains noninvasive (C. Zagaglia, M. Casalino, B. Colonna, C. Conti, A. Calconi, and M. Nicoletti, Infect. Immun. 59:792-799, 1991). In this work, we have studied the transcription of the virulence regulatory genes virB, virF, and hns (virR) in wild-type enteroinvasive E. coli HN280 and in its pINV-integrated derivative HN280/32. While transcription of virF and of hns is not affected by pINV integration, transcription of virB is severely reduced even if integration does not occur within the virB locus. This indicates that VirF cannot activate virB transcription when pINV is integrated, and this lack of expression accounts for the noninvasive phenotype of HN280/32. Virulence gene expression in strains HN280 and HN280/32, as well as in derivatives harboring a mxiC::lacZ operon fusion either on the autonomously replicating pINV or on the integrated pINV, was studied. The effect of the introduction of plasmids carrying virB (pBNI) or virF (pHW745 and pMYSH6504), and of a delta hns deletion, in the different strains was evaluated by measuring beta-galactosidase activity, virB transcription, and virB-regulated virulence phenotypes like synthesis of Ipa proteins, contact-mediated hemolysis, and capacity to invade HeLa cells. The introduction of pBN1 or of the delta hns deletion in pINV-integrated strains induces temperature-regulated expression or temperature-independent expression, respectively, of beta-galactosidase activity and of all virulence phenotypes, while an increase in virF gene dosage does not, in spite of a high-level induction of virB transcription. Moreover, a wild-type hns gene placed in trans fully reversed the induction of beta-galactosidase activity due to the delta hns deletion. These results indicate that virB transcription is negatively regulated by H-NS both at 30 and at 37 degrees C in pINV-integrated strains and that there is also a dose-dependent effect of VirF on virB transcription. The negative effect of H-NS on virB transcription at the permissive temperature of 37 degrees C could be due to changes in the DNA topology occurring upon pINV integration that favor more stable binding of H-NS to the virB promoter DNA region. At 30 degrees C, the introduction of the high-copy-number plasmid pMYSH6504 (but not of the low-copy-number pHW745) or of the deltahns deletion induces, in strains harboring an autonomously replicating pINV, beta-galactosidase activity, virB transcription, and expression of the virulence phenotypes, indicating that, as for HN280/32, the increase in virF gene dosage overcomes the negative regulatory effect of H-NS on virB transcription. Moreover, we have found that virF transcription is finely modulated by temperature and, with E. coli K-12 strains containing a virF-lacZ gene fusion, by H-NS. This leads us to speculate that, in enteroinvasive bacteria, the level of Virf inside the cell controls the temperature-regulated expression of invasion genes.