E. van de Vosse

Common variants at 11p13 are associated with susceptibility to tuberculosis

After imputation of data from the 1000 Genomes Project into a genome-wide dataset of Ghanaian individuals with tuberculosis and controls, we identified a resistance locus on chromosome 11p13 downstream of the WT1 gene (encoding Wilms tumor 1). The strongest signal was obtained at the rs2057178 SNP (P = 2.63 × 10−9). Replication in Gambian, Indonesian and Russian tuberculosis case-control study cohorts increased the significance level for the association with this SNP to P = 2.57 × 10−11.

Analysis of association of the TIRAP (MAL) S180L variant and tuberculosis in three populations

Reply to ”Analysis of association of the TIRAP (MAL) S180L variant and tuberculosis in three populations”

PARK2/PACRG polymorphisms and susceptibility to typhoid and paratyphoid fever

Host genetic factors may contribute to susceptibility to and outcome in infectious diseases. Recently polymorphisms in PARK2/PACRG, a gene cluster linked to ubiquitination and proteasome‐mediated protein degradation, were found to be associated with manifest infection by M. leprae. Here, we address whether these polymorphisms are associated with susceptibility to infection with Salmonella typhi and S. paratyphi A, intracellular pathogens that upon infection of humans share with mycobacteria aspects of the hosts’ immune response. The polymorphisms of PARK_e01(−697), PARK2_e01(−2599), rs1333955 and rs1040079 were analysed by polymerase chain reaction and restriction fragment length polymorphism in a case‐control study of typhoid and paratyphoid fever patients in an endemic area in Jakarta, Indonesia. For this study, samples were obtained from patients with blood culture‐confirmed typhoid fever (n = 90), paratyphoid fever (n = 26) and fever controls (n = 337) in a passive, community‐based surveillance and compared to those of randomly selected community controls (n = 322) from the same city area. The PARK2_e01(−2599) allele T was significantly associated with typhoid and paratyphoid fever (OR: 1·51, 95%CI: 1·02–2·23) but the other polymorphisms, PARK2_e01(−697), rs1333955 and rs1040079, were not associated. Although within the PARK2/PACRG gene cluster the PARK2_e01(−2599) allele T was most strongly associated with leprosy (OR∼ 3–5), the association with typhoid is much less strong. Our findings suggest that this polymorphism in PARK2/PACRG plays a small but significant role in susceptibility to the intracellular pathogens S. typhi and S. paratyphi.

Variation of CNV distribution in five different ethnic populations

Recent studies have revealed a new type of variation in the human genome encompassing relatively large genomic segments (∼100 kb–2.5 Mb), commonly referred to as copy number variation (CNV). The full nature and extent of CNV and its frequency in different ethnic populations is still largely unknown. In this study we surveyed a set of 12 CNVs previously detected by array-CGH. More than 300 individuals from five different ethnic populations, including three distinct European, one Asian and one African population, were tested for the occurrence of CNV using multiplex ligation-dependent probe amplification (MLPA). Seven of these loci indeed showed CNV, i.e., showed copy numbers that deviated from the population median. More precise estimations of the actual genomic copy numbers for (part of) the NSF gene locus, revealed copy numbers ranging from two to at least seven. Additionally, significant inter-population differences in the distribution of these copy numbers were observed. These data suggest that insight into absolute DNA copy numbers for loci exhibiting CNV is required to determine their potential contribution to normal phenotypic variation and, in addition, disease susceptibility.

Autophagy is redundant for the host defense against systemic Candida albicans infections

Autophagy has been demonstrated to play an important role in the immunity against intracellular pathogens, but very little is known about its role in the host defense against fungal pathogens such as Candida albicans. Therefore, the role of autophagy for the host defense against C. albicans was assessed by complementary approaches using mice defective in autophagy, as well as immunological and genetic studies in humans. Although C. albicans induced LC3-II formation in macrophages, myeloid cell-specific ATG7−/− mice with defects in autophagy did not display an increased susceptibility to disseminated candidiasis. In in vitro experiments in human blood mononuclear cells, blocking autophagy modulated cytokine production induced by lipopolysaccharide, but not by C. albicans. Furthermore, autophagy modulation in human monocytes did not influence the phagocytosis and killing of C. albicans. Finally, 18 single-nucleotide polymorphisms in 13 autophagy genes were not associated with susceptibility to candidemia or clinical outcome of disease in a large cohort of patients, and there was no correlation between these genetic variants and cytokine production in either candidemia patients or healthy controls. Based on these complementary in vitro and in vivo studies, it can be concluded that autophagy is redundant for the host response against systemic infections with C. albicans.

Polymorphisms in SP110 are not associated with pulmonary tuberculosis in Indonesians.

Despite being high transmissible, Mycobacterium tuberculosis (M. tuberculosis) infection causes active disease in only 5-10% of disease-susceptible individuals. This has instigated interest in studying potentially underlying genetic host factors and mechanisms in tuberculosis (TB). The recent identification of the Intracellular pathogen resistance 1 (Ipr1) gene, which plays a major role in controlling M. tuberculosis susceptibility and infection severity in mice (Pan et al., 2005), has prompted studies on its human homolog; SP110 in humans. Association of SP110 SNPs with pulmonary TB were first reported in a study on West African families (Tosh et al., 2006). Subsequent attempts to replicate these findings in other populations, including another West African (Ghanaian) cohort (Thye et al., 2006), however, were unsuccessful. Here we have genotyped 20 SNPs located in the SP110 gene, including the previously TB associated variants; rs2114592 and rs3948464, for the first time in a South East Asian cohort from Indonesia. Our study did not reveal any statistically significant associations between SP110 SNPs and pulmonary TB. In addition, a meta-analysis of the two previously TB associated SNPs revealed that these are not associated with TB, further confirming the lack of convincing evidence for SP110 to be implicated in TB susceptibility, as yet in humans.

“Mycobacterium tilburgii” Infection in Two Immunocompromised Children: Importance of Molecular Tools in Culture-Negative Mycobacterial Disease Diagnosis

ABSTRACT “Mycobacterium tilburgii” is a nontuberculous mycobacterium that cannot be cultured by current techniques. It is described as causing disseminated disease in adults. We present the first cases of disseminated disease in 2 immunocompromised children. This paper stresses the importance of molecular techniques for correct mycobacterial identification and guidance to immunological diagnosis.

Effect of amino acid substitutions in the human IFN-γR2 on IFN-γ responsiveness

Patients with interferon-γ receptor (IFN-γR) null mutations have severe infections with poorly pathogenic Mycobacteria. The IFN-γR complex involves two IFN-γR1 and two IFN-γR2 chains, in which several amino acid substitutions, some linked to disease and some apparently naturally occurring, have been described. We developed a model system to study functional effects of genetic variations in IFN-γR2. We retrovirally transduced wild-type IFN-γR2 and IFN-γR2 carrying presently known amino acid substitutions in various human cell lines, and next determined the IFN-γR2 expression pattern as well as IFN-γ responsiveness. We determined that the T58R, Q64R, E147K and K182E variants of IFN-γR2 are fully functional, although the Q64R variant may be expressed higher on the cell membrane. The R114C, T168N and G227R variants were identified in patients that had disseminated infections with non-tuberculous Mycobacteria. Of these genetic variants, T168N was confirmed to be completely non-functional, whereas the novel variant G227R, and the previously reported R114C, were partial functional. The impaired IFN-γ responsiveness of R114C and G227R is mainly due to reduced receptor function, although expression on the cell membrane is reduced as well. We conclude that the T58R, Q64R, E147K and K182E variants are polymorphisms, whereas the R114C, T168N and G227R constitute mutations associated with disease.

Mycobacterium bovis BCG-itis and cervical lymphadenitis due to Salmonella enteritidis in a patient with complete interleukin-12/-23 receptor β1 deficiency.

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare disorder with predisposition to severe, sometimes lethal, disease caused by otherwise poorly virulent, non-tuberculous environmental mycobacteria and poorly virulent salmonellae. In patients with MSMD, mutations have been identified in five genes that encode for the proteins IL-12/IL-23p40, IL-12/ IL-23Rβ1, IFN-コR1, IFN-γR2 and STAT1. These proteins play important roles in the type-1 cytokine pathway, which is crucial for human host defence against intracellular pathogens such as mycobacteria and salmonellae. We report a girl with mild Mycobacterium bovis Bacille Calmette–Guérin (BCG) disease and Salmonella enteritidis cervical lymphadenitis. Despite treatment, she has remained a fecal carrier of S. enteritidis for the past 14 years. She was found to have complete IL-12/IL-23Rβ1 deficiency. A homozygous r.518G>C IL12RB1 mutation was identified, leading to a non-functional R173P substitution in the IL-12/IL-23Rβ1 protein. This mutation abrogated IL-12/IL-23Rβ1 cell-surface expression and resulted in complete lack of T cell responsiveness to both IL-12 and IL-23.

Impaired cytokine responses in patients with cryopyrin-associated periodic syndrome (CAPS)

Cryopyrin‐associated periodic syndrome (CAPS) is characterized by dysregulated inflammation with excessive interleukin (IL)‐1β activation and secretion. Neonatal‐onset multi‐system inflammatory disease (NOMID) is the most severe form. We explored cytokine responses in 32 CAPS patients before and after IL‐1β blocking therapy. We measured cytokines produced by activated peripheral blood monuclear cells (PBMCs) from treated and untreated CAPS patients after stimulation for 48 h with phytohaemagglutinin (PHA), PHA plus IL‐12, lipopolysaccharide (LPS) or LPS plus interferon (IFN)‐γ. We measured IL‐1β, IL‐6, IL‐10, tumour necrosis factor (TNF), IL‐12p70 and IFN‐γ in the supernatants. PBMCs from three untreated CAPS patients were cultured in the presence of the IL‐1β blocker Anakinra. Fifty healthy individuals served as controls. CAPS patients had high spontaneous production of IL‐1β, IL‐6, TNF and IFN‐γ by unstimulated cells. However, stimulation indexes (SIs, ratio of stimulated to unstimulated production) of these cytokines to PHA and LPS were low in NOMID patients compared to controls. Unstimulated IL‐10 and IL‐12p70 production was normal, but up‐regulation after PHA and LPS was also low. LPS plus IFN‐γ inadequately up‐regulated the production of IL‐1β, IL‐6, TNF and IL‐10 in CAPS patients. In‐vitro but not in‐vivo treatment with Anakinra improved SIs by lowering spontaneous cytokine production. However, in‐vitro treatment did not improve the low stimulated cytokine levels. Activating mutations in NLRP3 in CAPS are correlated with poor SIs to PHA, LPS and IFN‐γ. The impairment in stimulated cytokine responses in spite of IL‐1β blocking therapy suggests a broader intrinsic defect in CAPS patients, which is not corrected by targeting IL‐1β.