According to the hygiene hypothesis, reduced exposure to infections could explain the rise of atopic diseases in high-income countries. Helminths are hypothesised to alter the host's immune... Show moreAccording to the hygiene hypothesis, reduced exposure to infections could explain the rise of atopic diseases in high-income countries. Helminths are hypothesised to alter the host's immune response in order to avoid elimination and, as a consequence, also reduce the host responsiveness to potential allergens. To elucidate the effect of current helminth infections on immune responsiveness in humans, we measured cytokine production in a rural Ghanaian population in an area with multiple endemic parasites including malaria, intestinal helminths and protozoa. Multiplex real-time PCR in stool samples was used for the detection of four gastrointestinal helminths, of which only Necator americanus was commonly present. A similar assay was used to test for Giardia lamblia in stool samples and malaria infection in venous blood samples. Levels of the cytokines interleukin (IL)-10, tumour necrosis factor (TNF)-α, IL-17, IL-6, IL-13, and interferon (IFN)-γ were determined in whole-blood samples ex vivo-stimulated either with lipopolysaccharide (LPS) and zymosan (for innate cytokine production) or the T-cell mitogen phytohaemagglutinin (PHA). There were no significant differences in either innate or PHA-stimulated cytokine production dependent on current N. americanus infection. Plasmodium falciparum malarial infection was associated with a pro-inflammatory response indicated by increased innate production of TNF-α, IL-17 and IL-6. There was no clear pattern in cytokine responses dependent on G. lamblia-infection. In conclusion, in this rural Ghanaian population current N. americanus infections are not associated with altered immune function, while infection with P. falciparum is associated with pro-inflammatory innate immune responses. Show less
Boef, A.G.C.; May, L.; Bodegom, D. van; Kuningas, M.; Eriksson, U.K.; Westendorp, R.G.J. 2012
Interleukin-10 (IL-10) production is under tight genetic control in populations living in affluent environments. However, little is known about the role of IL10 genetics on cytokine production in... Show moreInterleukin-10 (IL-10) production is under tight genetic control in populations living in affluent environments. However, little is known about the role of IL10 genetics on cytokine production in populations living in environments with high infectious pressure. We have previously reported that, in a rural Ghanaian population, the most common IL10 haplotype associates with a pro-inflammatory response. Here, we aim to replicate these findings in an independent sample of the same population 2 years later. IL-10 and tumour necrosis factor-α (TNF-α) protein concentrations were determined in whole-blood samples ex vivo stimulated with lipopolysaccharide and zymosan in 2006 (n=615) and 2008 (n=647). The association between IL10 single nucleotide polymorphisms and Z-scores of IL-10 and TNF-α levels was analysed in each population subset. The most common IL10 haplotype was associated with a significantly lower IL-10 production and nonsignificantly increased TNF-α levels. The correlation between repeated cytokine assays, based on 111 individuals with measurements in both 2006 and 2008, was r=0.53 (P<0.001) for IL-10 and r=0.36 (P<0.001) for TNF-α. The replication of our previously found effect of variation in the IL10 gene on IL-10 production and the correlation between repeated cytokine stimulation assays provide evidence that IL10 genetics have an important role in regulating the host response under high infectious pressure.Genes and Immunity advance online publication, 11 August 2011; doi:10.1038/gene.2011.57. Show less
Background: The prevalence of asthma and atopic disease has been reported to be low in low income countries, however helminth infections are likely to be high among these communities. The question... Show moreBackground: The prevalence of asthma and atopic disease has been reported to be low in low income countries, however helminth infections are likely to be high among these communities. The question of whether helminth infections play a role in allergic diseases can best be addressed by intervention studies. None of the studies so far have been based on a large scale placebo-controlled trial. Method/Design: This study was designed to assess how intestinal helminth infections can influence the immune response and atopic and allergic disorders in children in Indonesia. The relations between allergic outcomes and infection and lifestyle factors will be addressed. This study was set up among school-age children in semi urban and rural areas, located in Ende District of Flores Island, Indonesia. A randomized placebo-controlled anthelmintic treatment trial to elucidate the impact of helminth infections on the prevalence of skin prick test (SPT) reactivity and symptoms of allergic diseases will be performed. The children living in these semi-urban and rural areas will be assessed for SPT to allergens before and after 1 and 2 years of treatment as the primary outcome of the study; the secondary outcome is symptoms (asthma and atopic dermatitis); while the tertiary outcome is immune responses (both antibody levels to allergens and cellular immune responses). Discussion: The study will provide information on the influence of helminth infections and anthelmintic treatment on immune response, atopy and allergic disorders. Show less
Bodegom, D. van; Rozing, M.; May, L.; Kuningas, M.; Thomese, F.; Meij, H.; Westendorp, R. 2010
In a recent issue of this journal, Herndon [1] discussed the grandmother hypothesis and its implications for studies on cognitive ageing. According to this hypothesis, the long post-reproductive... Show moreIn a recent issue of this journal, Herndon [1] discussed the grandmother hypothesis and its implications for studies on cognitive ageing. According to this hypothesis, the long post-reproductive life span in human females is an adaptive mechanism that evolved to maximize female fitness by investing resources in the care of their grandchildren rather than by continuing to reproduce themselves. From this, Herndon deduces that special cognitive robustness to be maintained until after the age of menopause must have co-evolved because grandmothers can only exert the beneficial effect if their cognitive abilities remain intact. He therefore pleas to compare cognitive ageing in humans with other primates, especially chimpanzees, because they lack a long post-reproductive life span and would therefore not have evolved this cognitive robustness. Here, we question the important role of grandmothers in our evolutionary past, first because of the different family structures during this time and second because of the low number of females that actually lived to experience a post-reproductive lifespan. We also show that in a population that reflects our evolutionary past, grandmothers do not have an important role for child survival. Finally, we react on the implications for the study of cognitive ageing as put forward by Herndon. Copyright (C) 2009 S. Karger AG, Basel Show less
May, L.; Bodegom, D. van; Frolich, M.; Lieshout, L. van; Slagboom, P.E.; Westendorp, R.G.J.; Kuningas, M. 2010
Toll-like receptors (TLRs) are involved in the induction of an adequate immune response on infection. We hypothesized that genetic variation in TLR4 and TLR2 genes could influence this response and... Show moreToll-like receptors (TLRs) are involved in the induction of an adequate immune response on infection. We hypothesized that genetic variation in TLR4 and TLR2 genes could influence this response and lead to variability in cytokine production and survival. We tested this hypothesis in 4292 participants who were followed up for all-cause mortality for 6 years and live under adverse environmental conditions in the Upper-East region of Ghana, where malaria is endemic. In 605 participants, tumor necrosis factor-a and interleukin-10 (IL10) production, after stimulation with lipopolysaccharide and zymosan, was measured. In addition, 34 single-nucleotide polymorphisms (SNPs) in TLR4 and 12 SNPs in TLR2 were genotyped and tested for association with cytokine production, malaria infection and mortality. In this comprehensive gene-wide approach, we identified novel SNPs in the TLR4 gene that influence cytokine production. From the analyzed SNPs, rs7860896 associated the strongest with IL10 production (P=0.0005). None of the SNPs in this study associated with malaria or overall mortality risks. In conclusion, we demonstrate that genetic variation within the TLR4 gene influences cytokine production capacity, but in an endemic area does not influence the susceptibility to malaria infection or mortality. European Journal of Human Genetics (2010) 18, 490-495; doi:10.1038/ejhg.2009.182; published online 21 October 2009 Show less
Human fitness is critically reliant on the immune system to provide protection against pathogens. We argue that a pro-inflammatory response is crucial for defense against pathogens and that it is... Show moreHuman fitness is critically reliant on the immune system to provide protection against pathogens. We argue that a pro-inflammatory response is crucial for defense against pathogens and that it is very likely that infectious pressure has resulted in selective survival for genetic variants encoding for higher pro-inflammatory responsiveness. In industrialized populations many chronic diseases have been associated with an imbalance in pro- and anti-inflammatory responsiveness. We argue that from an evolutionary perspective, these chronic diseases in later life could be explained by genetic adaptations to survive a harsh environment. In order to study the role of the innate immune response in life-history regulation in a pathogen-rich environment, we set out a study in Northern Ghana. In a population living under adverse conditions we studied the role of the inflammatory response in survival and fertility. In Chapter 1 a general introduction was given on the research hypotheses and an overview of aims and description of the study population and methods. The general frame-work of the study was explained in depth in Chapter 2. Here we hypothesized that human life-history regulation in our evolutionary past, or under adverse conditions can largely be explained by selections that operated in the innate immune response. We proposed that fertility is associated with an anti-inflammatory response, whereas survival in a pathogen-rich environment is dependent on a strong pro-inflammatory response. We hypothesize that populations living under adverse conditions have been selected for a pro-inflammatory innate immune response. Also we argue that fitness in itself is a conflict between pro- and anti-inflammatory responsiveness where concessions have to be made to allow reproduction as well as defense. Furthermore we argue that evolutionary programming of the inflammatory response might underlie age-related diseases as observed in populations living under affluent conditions. It is arbitrary how to measure an innate immune response ex vivo, that reflects a general response mode irrespective the type of pathogen involved. In Chapter 3 a method is described to test innate tendency of immune activation. The assay is also validated. Given the fact that bacteria and other pathogens normally use several TLRs together to induce an immune response, we argue that mixed stimulation of both TLR2 and TLR4 receptors gives a broader view of an immune response than with the usual assay on a single TLR-agonist. Compared to variability of cytokine production in the Netherlands, we show that ex vivo IL10 production is comparable. Therefore we suggest that in Ghana IL10 is highly genetically regulated. TNF_, on the other hand, is more prone to variation in general, but especially in Ghana and might be more dependent on environmental modulation. In Chapter 4 we compared age-related cytokine production in adverse and affluent conditions. When measured cross-sectionally, IL10 production decreases with age in the Netherlands and in Ghana. TNF_ production decreases with age in the Netherlands, but remained equal over all age-categories in Ghana or, dependent on the stimulation, increased with age. We conclude that the decline in innate cytokine responses is an intrinsic ageing phenomenon, while pathogen exposure and/or selective survival may drive pro-inflammatory responses under adverse living conditions. As TLR2 and TLR4 are important recognition receptors for a large set of pathogens, it might be that variation in these receptors results in different induction of innate immune responses and selective survival. In Chapter 5 we report that at the end of the TLR4 gene there was variation that associated with higher ex vivo LPS-induced IL10 production. None of the variants in TLR2 or TLR4 however were associated with P. falciparum infection or survival. As the prevalence of malaria was high in this area, we conclude that it is likely that in contrast to other studies, these genetic variants do not play a role in disease state and outcome of infection. Another pathogen receptor is PTX3. It is not only involved in recognition of pathogens, but also in the formation of the extracellular matrix of the oocyte. Therefore it might be crucial for female fertility. In Chapter 6 we assess whether genetic variation in PTX3 production is associated with life-time reproductive success. We found genetic variants in PTX3 that associated with higher PTX3 production capacity ex vivo and increased fertility and vice versa. We found no evidence for selective survival of genetic variants. We conclude that PTX3 is important for human fertility, whereas no concessions were made with regard to survival. In Chapter 7 we asses the role of IL10 in survival. We report on genetic variation in the IL10 gene that associated with lower IL10 and higher TNF_ production. Carriers of these genetic variants had a higher survival chance when living under adverse conditions. However, survival chances of these variants decreased when people had access to clean drinking water. We conclude to have found evidence that adverse environmental conditions favor selection for a pro-inflammatory response pattern. Show less
Background: Given that helminth infections are thought to have strong immunomodulatory activity, the question whether helminth infections might affect responses to malaria antigens needs to be... Show moreBackground: Given that helminth infections are thought to have strong immunomodulatory activity, the question whether helminth infections might affect responses to malaria antigens needs to be addressed. Different cross-sectional studies using diverse methodologies have reported that helminth infections might either exacerbate or reduce the severity of malaria attacks. The same discrepancies have been reported for parasitemia. Methods/Design: To determine the effect of geohelminth infections and their treatment on malaria infection and disease outcome, as well as on immunological parameters, the area of Nangapanda on Flores Island, Indonesia, where malaria and helminth parasites are co-endemic was selected for a longitudinal study. Here a Double-blind randomized trial will be performed, incorporating repeated treatment with albendazole (400 mg) or placebo at three monthly intervals. Household characteristic data, anthropometry, the presence of intestinal helminth and Plasmodium spp infections, and the incidence of malaria episodes are recorded. In vitro cultures of whole blood, stimulated with a number of antigens, mitogens and toll like receptor ligands provide relevant immunological parameters at baseline and following 1 and 2 years of treatment rounds. The primary outcome of the study is the prevalence of Plasmodium falciparum and P. vivax infection. The secondary outcome will be incidence and severity of malaria episodes detected via both passive and active follow-up. The tertiary outcome is the inflammatory cytokine profile in response to parasite antigens. The project also facilitates the transfer of state of the art methodologies and technologies, molecular diagnosis of parasitic diseases, immunology and epidemiology from Europe to Indonesia. Discussion: The study will provide data on the effect of helminth infections on malaria. It will also give information on anthelminthic treatment efficacy and effectiveness and could help develop evidence-based policymaking. Show less
Kuningas, M.; Bodegom, D. van; May, L.; Meij, J.J.; Slagboom, P.E.; Westendorp, R.G.J. 2010
Various studies in mice have found support for the hypothesis that heterozygous carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations have an increased resistance to... Show moreVarious studies in mice have found support for the hypothesis that heterozygous carriers of cystic fibrosis transmembrane conductance regulator (CFTR) mutations have an increased resistance to fatal infection compared to both homozygous mutation carriers and non-carriers, while in humans such evidence is scarce. In this study, we assessed the CFTR heterozygotes survival advantage hypothesis in a contemporary rural population that lives under adverse environmental conditions in the Upper-East region of Ghana. We genotyped 30 SNPs throughout the CFTR gene in 4,230 participants and tested their influence on survival and on body composition in the population at large. With a sliding-window haplotype analysis, we identified a set of six common haplotypes that influenced survival probabilities (global p = 6.00 x 10(-05)). Individual haplotype analyses revealed two haplotypes of specific interest. One of these haplotypes was enriched (p = 0.003), whereas the other was depleted (p = 0.041) among people of old age (> or = 65 years) compared to young study participants (< or = 5 years). In addition, children (n = 474) carrying the latter haplotype had lower body weight (p (trend) = 0.020) and height (p (trend) = 0.010) compared to non-carriers. For all these analyses, similar associations for heterozygous and homozygous CFTR haplotype carriers were observed, revealing an additive effect of haplotype alleles. In conclusion, we identified common haplotypes in the CFTR gene that influence survival and body composition in the population at large with no evidence for heterozygote advantage. Show less
Kuningas, M.; Bodegom, D. van; May, L.; Meij, J.J.; Slagboom, P.E.; Westendorp, R.G.J. 2010
