Ex vivo simulation of IgG Fc and T-cell receptor functions: an application to inflammatory bowel disease

Aluminum as an adjuvant in Crohn's disease induction

Alum (AlK(SO(4))(2)) is an adjuvant commonly utilized in vaccines, and is a ubiquitous element used extensively in contemporary life. Food, air, water, waste, the earth's surface, and pharmaceuticals all represent pathways of aluminum (Al) exposure. Crohn's disease (CD) is a chronic relapsing intestinal inflammation in genetically susceptible individuals and is caused by yet unidentified environmental factors. Al is a potential factor for the induction of inflammation in CD, and its immune activities share many characteristics with the immune pathology of CD: many luminal bacterial or dietary compounds can be adsorbed to the metal surface and induce Th1 profile cytokines, shared cytokines/chemokines, co-stimulatory molecules, and intracellular pathways and stress-related molecular expression enhancement, affecting intestinal macrobiota, trans-mural granuloma formation, and colitis induction in an animal CD model. The inflammasome plays a central role in Al mode of action and in CD pathophysiology. It is suggested that Al adjuvant activity can fit between the aberrations of innate and adaptive immune responses occurring in CD. The CD mucosa is confronted with numerous inappropriate bacterial components adsorbed on the Al compound surface, constituting a pro-inflammatory supra-adjuvant. Al fits the diagnostic criteria of the newly described autoimmune/inflammatory syndrome induced by adjuvants. If a cause and effect relationship can be established, the consequences will greatly impact public health and CD prevention and management.

mRNA of the pro-apoptotic gene BBC3 serves as a molecular marker for TNF-α-induced islet damage in humans

AIMS/HYPOTHESIS

TNF-α plays important roles in the pathogenesis of type 1 and type 2 diabetes mellitus. In light of this, we examined the involvement of a pro-apoptotic gene, BBC3 (also known as PUMA), in TNF-α-mediated beta cell dysfunction and destruction in human islets.

METHODS

Human islets were exposed in vitro to TNF-α alone or in combination with IFN-γ. Gene expression was assessed by RT-PCR using a set of single islets. Protein abundance and cellular localisation of BBC3 were assessed by immunoblot and immunohistochemistry. A marginal number of islets were transplanted into diabetic NODscid mice to correlate in vivo islet function with BBC3 expression.

RESULTS

BBC3 and IL8 mRNA were upregulated in TNF-α-stimulated islets in a dose-dependent manner and enhanced through addition of IFN-γ, but not upregulated by IFN-γ alone. Immunohistochemistry revealed that TNF-α in combination with IFN-γ upregulated basal BBC3 abundance in the cytoplasm of beta cells along with the perinuclear clustering of mitochondria partially co-localised with BBC3. TNF-α alone did not induce beta cell death, but did abrogate preproinsulin precursor mRNA synthesis in response to high glucose stimulation, which was inversely associated with upregulation of BBC3 mRNA expression by TNF-α. Higher BBC3 mRNA expression in islets correlated with decreased graft function in vivo.

CONCLUSIONS/INTERPRETATION

These results suggest that BBC3 mRNA can serve as a molecular marker to detect early TNF-α-induced beta cell stress and may help identify islet-protective compounds for the treatment of diabetes.

Ex vivo simulation of leukocyte function: stimulation of specific subset of leukocytes in whole blood followed by the measurement of function-associated mRNAs

In order to characterize a wide spectrum of leukocyte functions with clinically applicable procedures, 0.06 ml each of heparinized whole blood was stimulated in triplicate for 4h with phytohemagglutinin (T cell stimulator), heat aggregated IgG (IgG Fc receptor stimulator), lipopolysaccharide (toll-like receptor (TLR)-4 stimulator), zymosan (TLR-2 stimulator), monoclonal antibody against T-cell receptor alpha/beta chain, recombinant interleukin-2, and solvent controls, then 32 different leukocyte function-associated mRNAs were quantified by the method reported previously (Mitsuhashi et al. Clin. Chem. 2006). Two control genes (beta-actin, beta-2-microglobulin) were not affected by these stimulations, whereas the induction of CCL chemokines-2, 4, 8, 20, CXCL chemokines-3, 10, interleukin (IL)-8 (markers of leukocyte accumulation/recruit), granzyme B, perforin 1, tumor necrosis factor superfamily-1, 2, 5, 14, 15, CD16 (markers of cell killing), IL10, transforming growth factor beta 1 (humoral factors of immune suppression), forkhead box P3, CD25, arginase (cellular markers of immune suppression), IL2, IL4, interferon-gamma, IL17 (markers of various subsets of T helper cells), granulocyte-macrophage colony-stimulating factor (marker of antigen presenting cells), immunoglobulin heavy locus (marker of B-cells), vascular endothelial growth factor (marker of angiogenesis), pro-opiomelanocortin (marker of local pain), and CD11a mRNA (marker of leukocyte adherence to endothelium) were identified by these stimulations. The blood volume in this assay was 1.44 ml, and 4 h' incubation in whole blood was physiological. Using triplicate aliquots of whole blood for both stimulant and solvent control, statistical conclusion was drawn for each stimulant for each mRNA. The method introduced in this study will be a new paradigm for clinical cellular immunology.

A dried tofu-supplemented diet affects mRNA expression of inflammatory cytokines in human blood

In order to develop a new model of diet research, blood was drawn from 12 adult volunteers for 3 wk on regular diets as controls, and for a subsequent 3 wk supplemented with 18.5 g of freeze-dried tofu (Koya tofu) every day. Triplicate aliquots of 0.06 mL each of whole blood were stimulated ex vivo with phytohemagglutinin (PHA)-P, heat aggregated human IgG (HAG), lipopolysaccharide (LPS), zymosan A, and anti-T cell receptor (TCR) monoclonal antibody to activate specific subsets of leukocytes, then the levels of various inflammatory cytokine mRNA were quantified by real time PCR. Koya tofu significantly (p<0.05) augmented the fold increase of PHA-induced tumor necrosis factor superfamily (TNFSF) 15, IL6, and IL8, HAG-induced TNFSF15 and IL8, LPS-induced IL6 and IL8, zymosan-induced TNFSF15, IL6 and IL8, and TCR-induced TNFSF2 in comparison to the regular diet. Such increase was due to the reduction of baseline mRNA expression, not the enhancement of mRNA induction after specific stimulations. Six (TNFSF15), 4 (IL6), and 3 (IL10) subjects showed significant reduction of baseline mRNA during the Koya tofu diet compared to that of the control diet. Despite large individual-to-individual and day-to-day variation of mRNA, the method employed in this study was sensitive enough to identify statistically significant results as a group as well as on an individual basis, which will be a foundation for tailored diet in the future. The results also indicated that Koya tofu had a power to alter mRNA expression in leukocytes, and TNFSF15, IL6, and IL10 would be biomarkers for soy.

Ex vivo TCR-induced leukocyte gene expression of inflammatory mediators is increased in type 1 diabetic patients but not in overweight children

BACKGROUND

Abnormal systemic concentrations of proinflammatory cytokines/chemokines have been implicated in the development of long-term cardiovascular complications in type 1 diabetes (T1DM) and obesity. Whether leukocyte white blood cell (WBC) gene expression of these proinflammatory mediators contributes to their increased systemic levels, however, remains unclear, especially in the pediatric patient populations. This study examines mRNA changes of 9 cytokines and chemokines in WBCs following ex vivo immunostimulation from 9 T1DM (13.4 +/- 0.5 year, 4F/5 M), 23 overweight (OW, 12.3 +/- 0.5 year, 10F/13M, BMI% 97.1 +/- 0.5 and > 90.0), and 21 healthy (CL, 13.8 +/- 0.7 year, 9F/12 M, BMI% 59.6 +/- 4.6 and < 85.0) children.

METHODS

All subjects had been maintained in euglycemic conditions for at least 90 min before blood draws. Whole blood was then sampled and incubated with anti-T-cell receptor (TCR) antibody or heat-aggregated IgG (HAG) to stimulate T-cell and Fc receptors (FcR), respectively. After lysis of leukocytes, mRNA levels of six tumor necrosis factor superfamily cytokines (TNFSF2, 5, 6, 7, 9, 14) and three chemokines (CCL8, 20, and CXCL10) were measured using RT-PCR.

RESULTS

Following TCR stimulation, T1DM displayed significantly greater mRNA responses than CL for TNFSF5, 7, 9, and CCL8, and CXCL10; TNFSF9, CCL8, and CXCL10 were also significantly higher in T1DM than OW; no difference was observed between OW and CL. FcR stimulation induced similar responses across groups.

CONCLUSIONS

Leukocytes of T1DM children displayed exaggerated gene expression in response to ex vivo TCR induction of five key proinflammatory cytokines/chemokines. This elevated leukocyte gene expression may be one of the pathophysiological contributors to the development of vascular complications in T1DM.

Diverse genome-wide association studies associate the IL12/IL23 pathway with Crohn Disease

Previous genome-wide association (GWA) studies typically focus on single-locus analysis, which may not have the power to detect the majority of genuinely associated loci. Here, we applied pathway analysis using Affymetrix SNP genotype data from the Wellcome Trust Case Control Consortium (WTCCC) and uncovered significant association between Crohn Disease (CD) and the IL12/IL23 pathway, harboring 20 genes (p = 8 x 10(-5)). Interestingly, the pathway contains multiple genes (IL12B and JAK2) or homologs of genes (STAT3 and CCR6) that were recently identified as genuine susceptibility genes only through meta-analysis of several GWA studies. In addition, the pathway contains other susceptibility genes for CD, including IL18R1, JUN, IL12RB1, and TYK2, which do not reach genome-wide significance by single-marker association tests. The observed pathway-specific association signal was subsequently replicated in three additional GWA studies of European and African American ancestry generated on the Illumina HumanHap550 platform. Our study suggests that examination beyond individual SNP hits, by focusing on genetic networks and pathways, is important to unleashing the true power of GWA studies.

Trastuzumab-induced CCL20 and interleukin-8 mRNA in human whole blood ex vivo

Heparinized human whole blood from 16 adult volunteers was stimulated with achievable blood concentrations of trastuzumab and rituximab at 37 degrees C for 4 h, then CCL20, IL8, and beta-actin mRNA were quantified. The fold increase of beta-actin was all less than 1.5, and heat aggregated IgG induced both IL8 and CCL20 mRNA in all cases, suggesting that the assay was performed appropriately. Rituximab reduced the levels of CCL20 mRNA in approximately 1/3 of subjects, whereas 50 μg/ml trastuzumab induced IL8 and CCL20 mRNA in more than half of subjects. Although the results do not directly indicate the toxicity of antibody medicines, the individual variation found under physiological ex vivo condition will be an interesting clinical research model for drug safety analysis.