Inflammatory immune disorders such as inflammatory bowel disease and multiple sclerosis are major health problems. Currently, the intestinal whipworm Trichuris suis is being explored in clinical ...trials to reduce inflammation in these diseases; however, the mechanisms by which the parasite affects the host immune system are not known. Here we determined the effects of T. suis soluble products (SPs) on Toll-like receptor-4 (TLR4)-stimulated human dendritic cells (DCs) using Illumina bead chip gene arrays. Pathway analysis of lipopolysaccharide-stimulated DCs with or without T. suis treatment showed that co-stimulation with T. suis SPs resulted in a downregulation of both the myeloid differentiation primary response gene 88-dependent and the TIR-domain-containing adaptor-inducing interferon-β-dependent signalling pathways triggered by TLR4. These data were verified using quantitative real-time PCR of several key genes within these pathways and/or defining their protein levels. In addition, T. suis SPs induce Rab7b, a negative regulator of TLR4 signalling that interferes with its trafficking, which coincided with a reduced surface expression of TLR4. These data indicate that the mechanism by which T. suis SPs reduce inflammatory responses is through suppression of both TLR4 signalling and surface expression on DCs.
Transcription profiling of rheumatic diseases van Baarsen, Lisa G M; Bos, Carina L; van der Pouw Kraan, Tineke C T M ...
Arthritis research & therapy,
01/2009, Letnik:
11, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Rheumatic diseases are a diverse group of disorders. Most of these diseases are heterogeneous in nature and show varying responsiveness to treatment. Because our understanding of the molecular ...complexity of rheumatic diseases is incomplete and criteria for categorization are limited, we mainly refer to them in terms of group averages. The advent of DNA microarray technology has provided a powerful tool to gain insight into the molecular complexity of these diseases; this technology facilitates open-ended survey to identify comprehensively the genes and biological pathways that are associated with clinically defined conditions. During the past decade, encouraging results have been generated in the molecular description of complex rheumatic diseases, such as rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome and systemic sclerosis. Here, we describe developments in genomics research during the past decade that have contributed to our knowledge of pathogenesis, and to the identification of biomarkers for diagnosis, patient stratification and prognostication.
Rheumatoid arthritis (RA) is a heterogeneous disease. We used cDNA microarray technology to subclassify RA patients and disclose disease pathways in rheumatoid synovium. Hierarchical clustering of ...gene expression data identified two main groups of tissues (RA-I and RA-II). A total of 121 genes were significantly higher expressed in the RA-I tissues, whereas 39 genes were overexpressed in the RA-II tissues. Among the 121 genes overexpressed in RA-I tissues, a relative majority of nine genes are located on chromosome 6p21.3. An interpretation of biological processes that take place revealed that the gene expression profile in RA-I tissues is indicative for an adaptive immune response. The RA-II group showed expression of genes suggestive for fibroblast dedifferentiation. Within the RA-I group, two subgroups could be distinguished; the RA-Ia group showed predominantly immune-related gene activity, while the RA-Ib group showed an additional higher activity of genes indicative for the classical pathway of complement activation. All tissues except the RA-Ia subgroup showed elevated expression of genes involved in tissue remodeling. These results confirm the heterogeneous nature of RA and suggest the existence of distinct pathogenic mechanisms that contribute to RA. The differences in expression profiles provide opportunities to stratify patients based on molecular criteria.
IL-13 plays a crucial role in the development of allergic asthma by several mechanisms, including induction of IgE antibodies, airway eosinophilia and hyper-reactivity. We previously established a ...deregulated production of IL-13 by T cells from allergic asthma patients. In this report we describe the identification of a novel IL-13 promoter polymorphism (C to T exchange) at position -1055. The IL-13 -1055 TT genotype is associated with allergic asthma (P = 0.002), altered regulation of IL-13 production (P < 0.002), and increased binding of nuclear proteins to this region. We postulate that the presence of this polymorphism predisposes to the development of allergic asthma.
Given the heterogeneous nature of multiple sclerosis (MS), we applied DNA microarray technology to determine whether variability is reflected in peripheral blood (PB) cells. In this study, we studied ...whole-blood gene expression profiles of 29 patients with relapsing-remitting MS (RRMS) and 25 age- and sex-matched healthy controls. We used microarrays with a complexity of 43K cDNAs. The data were analyzed using sophisticated pathway-level analysis in order to provide insight into the deregulated peripheral immune response programs in MS. We found a remarkable elevated expression of a spectrum of genes known to be involved in immune defense in the PB of MS patients compared to healthy individuals. Cluster analysis revealed that the increased expression of these genes was characteristic for approximately half of the patients. In addition, the gene signature in this group of patients was comparable with a virus response program. We conclude that the transcriptional signature of the PB cells reflects the heterogeneity of MS and defines a sub-population of RRMS patients, who exhibit an activated immune defense program that resembles a virus response program, which is supportive for a link between viruses and MS.
During human immunodeficiency virus infection and allergic diseases, characterized by a dominant T helper (Th) 2 response, overproduction of prostaglandin E2 (PGE2) is observed. In this paper we ...studied the effect of PGE2 on interleukin (IL)-12 synthesis, because this cytokine has been described to be essential in induction of Th1 responses. IL-12 synthesis was induced in monocytes that were stimulated with Neisseria meningitidis-derived lipopolysaccharide in whole blood cultures. PGE2 almost completely inhibited lipopolysaccharide induced IL-12 production, whereas IL-6 production was only partially inhibited by PGE2. In contrast, the production of IL-10 was approximately twofold enhanced at these conditions. The effects of PGE2 were due to its cAMP-inducing capacity, since they could be mimicked by other cAMP inducers. Recombinant human IL-10 also inhibited IL-12 and IL-6 production. However, the inhibitory effect of PGE2 on IL-12 production was independent of IL-10 since neutralizing anti-IL-10 antibodies were unable to reverse this inhibition. These results suggest that the capacity of an antigen to induce PGE2 synthesis may play a crucial role in the development of either a Th1 or Th2 response.
IL-12 enhances IFN-gamma production by NK cells and T lymphocytes and plays a pivotal role in the development of Th1 cells. Bioactive IL-12 (p70) is composed of two subunits, p35, which is only ...secreted as part of the p70 dimer, and p40, which can also be secreted by itself. The IL-12 subunits are encoded by two separate genes. Therefore, we studied to what extent the expression of each of the subunits contributes to the regulation of IL-12 production. We found that in LPS-stimulated whole blood and purified monocytes, p70 and p40 production are enhanced by IFN-gamma and inhibited by IL-10 and IL-4. However, IFN-gamma and IL-10 had stronger effects on p70 production than on p40 production, and IL-4 affected p40 production more strongly. Concomitantly, in all experimental conditions tested, p40 production greatly exceeded p70 production, suggesting that p35 expression was limiting. Analysis of p35 and p40 mRNA expression by PCR confirmed this notion. Resting purified monocytes expressed neither p40 nor p35 mRNA. The effects of IFN-gamma, IL-10, and IL-4 on the p35 mRNA expression in LPS-stimulated purified monocytes were similar to the effects of these cytokines on p70 protein production, and the p40 mRNA expression corresponded to p40 protein production. Our results imply that production of the two IL-12 subunits is differently regulated for each subunit, mainly at the level of mRNA expression, and that the level of bioactive IL-12 production in monocytes in response to LPS and cytokines is determined by the level of p35 expression.
IL-13 is strongly implicated in the development of asthma and chronic obstructive pulmonary disease (COPD). We previously identified an IL-13 promoter polymorphism (-1055 C to T) that is associated ...with allergic asthma. We now report an increased frequency of the -1055 T allele in COPD patients compared to healthy controls (P=0.002) and compared to a second control group consisting of smoking individuals with normal lung function (P=0.01). A closely linked IL-13 exon polymorphism is present at normal allelic frequencies (P=0.3 and 0.4, respectively). In addition, we observed a normal distribution of two IL-4 polymorphisms at positions -590 and +33 (P=0.2 and 0.9, respectively). These results could implicate a functional role for the IL-13 promoter polymorphism in the enhanced risk to develop COPD.
In atopic patients, allergen-specific T cells have acquired the Th2 phenotype, which is considered to be responsible for the class switch to IgE Ab formation. Because IL-12 is a key cytokine for the ...induction of Th1 responses, a reduced capacity to produce this cytokine could lead to aberrant Th2 development. Therefore, we examined the production of IL-12 in whole blood cultures from patients with allergic asthma (n = 15) in comparison with nonatopic control subjects (n = 15) to different stimuli. After stimulation with Staphylococcus aureus Cowan I strain (SAC) we observed a 2.6-fold reduction of IL-12 p70 production in the patient group (p < 0.005). This was not due to a general failure of monocytes from these patients to produce cytokines, because the production of IL-6 was normal. SAC also induced the production of IFN-gamma, which was blocked by neutralization of IL-12. In line with the reduced levels of IL-12 secretion, the patient group showed a 3-fold reduction of IL-12-dependent IFN-gamma production (p < 0.005). The amounts of IL-12 and IFN-gamma were positively correlated in both the patient (R = 0.51 at 0.05% SAC and R = 0.64 at 0.01% SAC) and the control groups (R = 0.64 at 0.05% SAC and R = 0.70 at 0.01% SAC). The IFN-gamma:IL-12 ratio was not different between patients and control subjects, indicating a normal response to IL-12. Diminished production of IL-12 and IFN-gamma could not be explained by an increased production of IL-10, because in SAC-stimulated cultures IL-10 was hardly induced in both groups. Furthermore, after stimulation with Escherichia coli, the production of IL-10 was similar in patients and control subjects.
IgE antibodies play a crucial role in allergic type I reactions. Only IL‐4 and IL‐13 are able to induce an immunoglobulin isotype switch to IgE in B cells. A major question is to what extent these ...cytokines contribute to the production of IgE in allergic patients. To address this question we used an in vitro culture system in which the production of IgE is dependent on endogenously produced IL‐4 and IL‐13. In cultures of purified T and B cells from allergic asthma patients and non‐atopic controls, T cells were polyclonally stimulated to obtain IL‐4, IL‐13 and subsequently IgE secretion. The absolute amount of IgE produced was not significantly different between patients and controls. When neutralizing IL‐4 antibodies were included during culture, the production of IgE was dramatically inhibited in both patients and controls (production of IgE was reduced to 12%). However, neutralization of IL‐13 led to a significantly stronger inhibition of IgE production in the patient group: production of IgE was reduced to 23 ± 3% versus 50 ± 10% in the control group. Corresponding with these results, we also observed a higher production of IL‐13 by the patients, while the production of IL‐4 was not significantly different. A more detailed analysis of the production of IL‐13 revealed that patients' T cells were less sensitive to a negative signal controlling IL‐13 production. Our results indicate that, at least in vitro, IgE production in allergic asthma patients is more dependent on IL‐13 than in non‐atopics, due to enhanced IL‐13 production and to enhanced IgE production in response to IL‐13.
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