Aize Kijlstra

Control of the risk of human toxoplasmosis transmitted by meat.

One-third of the human world population is infected with the protozoan parasite Toxoplasma gondii. Recent calculations of the disease burden of toxoplasmosis rank this foodborne disease at the same level as salmonellosis or campylobacteriosis. The high disease burden in combination with disappointing results of the currently available treatment options have led to a plea for more effective prevention. In this review we describe Toxoplasma as a hazard associated with the consumption of undercooked meat or meat products and provide an analysis of the various options to control the risk of human toxoplasmosis via this source. Monitoring and surveillance programs may be implemented for pre-harvest control of Toxoplasma infection of farm animals, with the reduction of environmental oocyst load as the most important milestone. Alternatively, Toxoplasma safe meat can be obtained through simple post-harvest decontamination procedures, whereby freezing the meat may currently be the best option, although new technologies using irradiation or high-pressure treatment may offer promising alternatives. Influence of culture, religion and food handling customs may predispose a certain type of meat as an important source of infection, indicating that prevention needs to be tailored according to social habits in different regions in the world. The rationale for more stringent control measures to prevent toxoplasmosis both from disease and economic points of view is emphasized.

Toxoplasma-safe meat: close to reality?

In 2008, the centennial of the discovery of Toxoplasma gondii was celebrated. However, toxoplasmosis is still seen as a neglected and underreported disease, despite having a disease burden similar to that of salmonellosis and campylobacteriosis. Human vaccines are not available and current antiparasitic treatment is disappointing. This has led to an urge to focus more on prevention. Food, soil or water contaminated with oocysts from cat faeces and undercooked meat from infected intermediate hosts are important routes of infection. Oocyst contamination is difficult to control, whereas in Western countries, the control of T. gondii in meat should be feasible. Here, we discuss strategies aimed at developing a Toxoplasma-safe meat chain.

Immunological Factors in the Pathogenesis and Treatment of Age-Related Macular Degeneration

Recent findings indicate that immunological factors are involved not only in the pathogenesis of age-related macular degeneration (AMD), but also in its treatment. Earlier data showing the presence of inflammatory cells in affected areas of AMD retinas support this statement. Although a possible role for autoimmunity was initially suggested, it has never reached general acceptance. Microorganisms have also been implied in the pathogenesis of AMD. Both serum antibacterial antibody levels and positive DNA tests from neovascular membranes have pointed to a possible role for Chlamydia pneumoniae in the pathogenesis of AMD. New data is providing evidence for the hypothesis that deposits between Bruchs membrane and the retinal pigment epithelium (RPE) cell layer may act as a stimulus for the local activation of the complement system. This may lead to a further growth of the deposits due to the strong chemotactic activity of certain complement activation products (such as C5a) with an influx of inflammatory cells. The buildup of cells and extracellular deposits may lead to local ischemia resulting in the activation of RPE cells. These activated RPE cells are thought to release angiogenic stimuli leading to choroidal neovascularization, which is the most serious complication of AMD. The fact that immunosuppressive drugs such as triamcinolone acetonide and anecortave acetate are capable of inhibiting choroidal neovascularization is consistent with an inflammatory component in the pathogenesis of AMD. Specific immunotherapy directed at certain cytokines or growth factors is now being investigated at both the animal and patient levels. Various clinical trials involving engineered antibodies are now being applied to block angiogenic factors such as the vascular endothelial growth factor (VEGF). An approach using gene therapy to influence angiogenesis by inducing the production of the pigment epithelium-derived factor (PEDF) was able to block neovascularization in an experimental murine model. Besides trying to block ongoing processes in AMD, retinal transplantation is now also being investigated as a treatment option. The fact that the retina is possibly an immunoprivileged tissue in combination with experimental data showing that the subretinal space is an immunoprivileged site is an indication that transplantation would not suffer from the rejection process. A larger obstacle is the question whether transplanted retinal tissue will regain its functional properties.

IL-23R gene confers susceptibility to Behcet's disease in a Chinese Han population

Purpose IL-23 has been shown to be involved in the pathogenesis of Behcets disease (BD) through promoting IL-17 production. This study examined whether IL-23R polymorphisms were associated with susceptibility to this disease in a Chinese Han population. Methods Four single-nucleotide polymorphisms (SNP), rs7517847, rs11209032, rs 1343151 and rs17375018 were genotyped in 338 BD patients and 407 age, sex and ethnically matched healthy controls using a PCR restriction fragment length polymorphism assay. Results A significantly increased prevalence of the homozygous rs17375018 GG genotype and G allele was found in BD patients compared with controls (corrected p (pc)<0.001,odds ratio (OR) 1.86, 95% CI 1.39 to 2.49; pc<0.001, OR 1.57, 95% CI 1.25 to 1.98, respectively). The frequencies of the AA genotype and A allele of the SNP rs11209032 were significantly higher in BD patients compared with controls (pc=0.024, OR 1.69, 95% CI 1.21 to 2.35; pc<0.001, OR 1.48, 95% CI 1.21 to 1.82, respectively). In addition, the results showed a significantly decreased frequency of the AGCG haplotype in BD patients compared with controls (pc=0.0016, OR 0.59, 95% CI 0.45 to 0.77). Conclusions This study, for the first time, identified a strong association of an SNP of IL-23R, rs17375018, with BD. The results also suggested that both rs11209032 AA and rs17375018 GG of IL-23R are predisposing genotypes for BD and that the AGCG haplotype may provide protection against BD.

Changing climate—changing pathogens: Toxoplasma gondii in North-Western Europe

In this review, we describe the effects of global climate change for one specific pathogen: the parasite Toxoplasma gondii. It is postulated that an increase of T. gondii prevalence in humans can occur in some regions of North-Western Europe as a result of changing environmental conditions. Such a change can be predicted by using Global Climate Change models. We have elaborated such a prediction for one scenario (SRES A1) by using one specific model (CCSR/NRIES) as an example. Next to environmental factors, also anthropogenic factors may contribute to increased prevalence of T. gondii in this region. In order to counter the potential severe consequences of a potential increase resulting from the combination of climatic and anthropogenic factors, there is an urgent need for the development of a human vaccine. Until a vaccine that offers complete protection is developed, the emphasis should be on treatment optimization and prevention.

MicroRNA-146a and Ets-1 gene polymorphisms in ocular Behçet's disease and Vogt–Koyanagi–Harada syndrome

Aim MicroRNA-146a (miR-146a) is involved in certain immune-mediated diseases. Transcription factor Ets-1 strongly affects miR-146a promoter activity and directly regulates miR-146a expression. This study was performed to investigate the association of miR-146a and Ets-1 gene polymorphisms with Behçets disease (BD) and Vogt–Koyanagi–Harada (VKH) disease in a Chinese Han population. Methods A total of 809 patients with BD, 613 patients with VKH and 1132 normal controls were genotyped for miR-146a/rs2910164, rs57095329 and rs6864584, Ets-1/rs1128334 and rs10893872 using a PCR restriction fragment length polymorphism assay. miR-146a expression was examined in peripheral blood mononuclear cells (PBMCs) by real-time PCR. Cytokine production by PBMCs was measured by ELISA. Results A significantly decreased frequency of the homozygous rs2910164 CC genotype and C allele was observed in patients with BD compared with controls (pca=1.24×10−5, OR 0.61; pca=1.33×10−4, OR 0.75, respectively). MiR-146a expression in GG cases was 2.45-fold and 1.99-fold higher, respectively, than that in CC cases and GC cases. There was no association of the other four single nucleotide polymorphisms (SNPs) with BD. There was also no association of these five SNPs with its main clinical features. No associations were found with the five SNPs tested or with its clinical manifestations in VKH disease. Interleukin (IL)-17, tumour necrosis factor (TNF)α and IL-1β production from rs2910164 CC cases was markedly lower than that in GG cases. No effect of genotype was observed on IL-6 and monocyte chemoattractant protein (MCP)-1 production and IL-8 expression was slightly higher in CC cases. Conclusions Our study identified a strong association of rs2910164 of miR-146a with BD in a Chinese population and decreased expression of miR-146a and certain proinflammatory cytokines in individuals carrying the CC genotype.

The Effects of Th17 Cytokines on the Inflammatory Mediator Production and Barrier Function of ARPE-19 Cells

Th17 cells have emerged as a key factor in the pathogenesis of uveitis as well as other autoimmune disorders. They secrete a number of cytokines including IL-17A, IL-17F and IL-22 and until now the effects of these cytokines on resident cells of the eye were not yet clear. The purpose of this study was to investigate the effects of Interleukin (IL)-17A, IL-17F and IL-22 on the production of inflammatory mediators and barrier function of retinal pigment epithelium cells. We showed that ARPE-19 cells, a spontaneously arisen cell line of retinal pigment epithelium (RPE), constitutively expressed IL-17RC and IL-22R, but not IL-17RA. IL-17A significantly enhanced the production of CXCL8, CCL2, CCL20 and IL-6 by these cells. IL-17F had a similar effect on the production of CXCL8, CCL2 and IL-6 by ARPE-19 cells, but did not influence the expression of CCL20. Both IL-17A and IL-17F significantly decreased the transepithelial electrical resistance (TER) of the ARPE-19 monolayer and increased the diffusion rate of fluorescein isothiocyanate (FITC)-dextran. They also disrupted the distribution of the junction proteins zonula occludens (ZO)-1 and occludin at the interface of adjacent cells. IL-22 did not have a detectable effect on the production of the tested inflammatory mediators by ARPE-19 cells, TER of the ARPE-19 monolayer, the diffusion rate of FITC-dextran or the distribution of ZO-1 and occludin. This study demonstrates that IL-17A and IL-17F, but not IL-22, significantly promoted ARPE-19 cells to secrete inflammatory mediators and compromised the ARPE-19 monolayer barrier function in association with a disrupted distribution of ZO-1 and occludin. These results suggest that both IL-17A and IL-17F may play a role in posterior segment inflammation of the eye.

JAK2 and STAT3 Polymorphisms in a Han Chinese Population with Behçet's Disease

PURPOSE Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) polymorphisms have been demonstrated as a common risk factor for a number of autoimmune diseases. The aim of this study was to investigate the association of JAK2 and STAT3 polymorphisms with Behçets disease (BD) in a Han Chinese population. METHODS A case-control study was performed in 503 Chinese patients with BD and 615 healthy controls. The genotypes of three single-nucleotide polymorphisms (SNPs) (rs10758669, rs7857730, rs10119004) in the JAK2 and four SNPs (rs6503695, rs744166, rs2293152, and rs12948909) in the STAT3 gene were analyzed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). In all, 10% of the samples were sequenced to validate the result of PCR-RFLP. The χ(2) test was performed to compare allele and genotype distributions and Bonferroni correction was applied for multiple comparisons. RESULTS A deviation from the Hardy-Weinberg equilibrium was not found in all controls tested. A significantly increased frequency of the GG genotype of the STAT3 rs2293152 was observed in patients with BD (Bonferroni-corrected P value = 0.021). None of the tested SNPs of JAK2 was associated with BD. Stratification analysis according to oral ulceration, genital ulceration, skin lesions, and arthritis for BD did not reveal an association. CONCLUSIONS These results suggest that a STAT3 genetic polymorphism is associated with the susceptibility to BD.

The Effect of Modified Eggs and an Egg-Yolk Based Beverage on Serum Lutein and Zeaxanthin Concentrations and Macular Pigment Optical Density: Results from a Randomized Trial

Increasing evidence suggests a beneficial effect of lutein and zeaxanthin on the progression of age-related macular degeneration. The aim of this study was to investigate the effect of lutein or zeaxanthin enriched eggs or a lutein enriched egg-yolk based buttermilk beverage on serum lutein and zeaxanthin concentrations and macular pigment levels. Naturally enriched eggs were made by increasing the levels of the xanthophylls lutein and zeaxanthin in the feed given to laying hens. One hundred healthy volunteers were recruited and randomized into 5 groups for 90 days. Group one added one normal egg to their daily diet and group two received a lutein enriched egg-yolk based beverage. Group three added one lutein enriched egg and group four one zeaxanthin enriched egg to their diet. Group five was the control group and individuals in this group did not modify their daily diet. Serum lutein and zeaxanthin concentrations and macular pigment densities were obtained at baseline, day 45 and day 90. Macular pigment density was measured by heterochromatic flicker photometry. Serum lutein concentration in the lutein enriched egg and egg yolk-based beverage groups increased significantly (p<0.001, 76% and 77%). A strong increase in the serum zeaxanthin concentration was observed in individuals receiving zeaxanthin enriched eggs (P< 0.001, 430%). No changes were observed in macular pigment density in the various groups tested. The results indicate that daily consumption of lutein or zeaxanthin enriched egg yolks as well as an egg yolk-based beverage show increases in serum lutein and zeaxanthin levels that are comparable with a daily use of 5 mg supplements. Trial Registration ClinicalTrials.gov NCT00527553

Monocyte chemoattractant protein-1 -2518 A/G single nucleotide polymorphism in Chinese Han patients with ocular BehçEt's disease.

Recent studies in Caucasian uveitis patients have shown an association with the -2518 A/G polymorphism of the monocyte chemoattractant protein (MCP)-1 gene. It is unknown whether this polymorphism is also associated with ocular Behçets disease (BD) in Chinese populations. The aim of the current study was therefore to investigate the possible involvement of MCP-1 in the susceptibility to ocular BD in Chinese Han individuals. A case control association study was performed in 296 ocular BD patients and 319 geographically and age-matched healthy controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Binary logistic regression analysis revealed a decreased frequency of the homozygous AA genotype and an increased frequency of AG genotype of the MCP-1 -2518 polymorphism in ocular BD patients compared with healthy controls, when adjusted for gender (p = 0.048, p = 0.028, respectively). However, when segregated on the basis of several clinical findings, no any association was found between this polymorphism and ocular BD. In conclusion, the present study suggests that the MCP-1 -2518 AA genotype seems to display a protective association with ocular BD, whereas the -2518 AG genotype might be a susceptible factor for ocular BD in the Chinese Han population.