P-selectin-dependent platelet aggregation and apoptosis may explain the decrease in platelet count during Helicobacter pylori infection.

P-selectin expression has been shown in Helicobacter pylori-infected persons, an infection that has been clinically associated with platelet-related diseases, such as idiopathic thrombocytopenic purpura. However, the role of P-selectin expression during H pylori infection remains unclear. In this study, we hypothesized that P-selectin expression was associated with platelet aggregation during H pylori infection. Using flow cytometry, we examined the levels of adhesion between H pylori and platelets as well as the levels of P-selectin expression and platelet phosphatidylserine (PS) expression during H pylori infection. Significantly high levels of adhesion between pro-aggregatory bacteria and platelets were observed. We identified that H pylori IgG is required for bacteria to induce P-selectin expression and that a significant release of P-selectin is essential for H pylori to induce aggregation. In addition, cellular apoptotic signs, such as membrane blebbing, were observed in platelet aggregates. PS expression was also detected in platelets during infection with both pro-aggrogatory and nonaggregatory strains of H pylori. These results suggest that the decrease in platelet counts seen during H pylori infection is the result of P-selection-dependent platelet aggregation and PS expression induced by the bacteria.

SUMO regulates the cytoplasmonuclear transport of its target protein Daxx.

It is known that Fas death domain-associated protein (Daxx) possesses both putative nuclear and cytoplasmic functions. However, the nuclear transport mechanism is largely unknown. This study examined the nuclear location signal (NLS) of Daxx and whether the nuclear transport of Daxx was mediated by small ubiquitin-related modifier (SUMO). Two NLS motifs of Daxx, leucine (L)-rich nuclear export signal (NES)-like motif (188IXXLXXLLXL197) and C-terminal lysine (K) rich NLS2 (amino acids 627-634) motif, were identified and the K630 and K631 on the NLS2 motif were characterized as the major sumoylation sites of Daxx by in vitro sumoylation analysis. Proteins of inactive SUMO (SUMO-delta), a sumoylation-incompetent mutant, and Daxx NLS mutants (Daxx-NES(mut) and Daxx NLS2(mut)) were dispersed in cytoplasm. The cytoplasmic dispersed Daxx mutants could be relocalized to nucleus by cotransfection with active SUMO, but not with inactive SUMO-delta, demonstrating the role of SUMO on regulating the cytoplasmonuclear transport of Daxx. However, inactive SUMO-delta could also be relocalized to nucleus during cotransfection with wild-type Daxx, suggesting that SUMO regulation of the cytoplasmonuclear transport of its target protein Daxx does not need covalent modification. This study shows that cytoplasmic SUMO has a biological role in enhancing the cytoplasmonuclear transport of its target protein Daxx and it may be done through the non-sumoylation interactions.

Tumor necrosis factor-beta +252A polymorphism is associated with systemic lupus erythematosus in Taiwan.

BACKGROUND AND PURPOSE: Cytokine network alterations contribute strongly to the initiation and perpetuation of systemic lupus erythematosus (SLE). This study investigated the cytokines production and polymorphism association of cytokines with SLE in Taiwan. The cytokines investigated included tumor necrosis factor-alpha (TNF-alpha), TNF-beta (TNF-beta), interleukin (IL)-4, IL-10 and transforming growth factor-beta1 (TGF-beta1). METHODS: Genotyping of different cytokine genes was performed using polymerase chain reaction and restriction fragment length polymorphism methods in 136 patients. The cytokine levels in the supernatants of cultures of peripheral blood mononuclear cells (PBMCs) were determined by enzyme immunoassay. RESULTS: The rates of genotype polymorphism of TNF-beta +252, IL-4 -590 and IL-10 -819 were significantly correlated with SLE. However, only the genotype frequency of TNF-beta +252A was in accordance with Hardy-Weinberg equilibrium and significantly greater than in the normal group. The stimulated PBMC culture supernatants from TNF-beta +252A carriers produced lower levels of TNF-beta compared to TNF-beta +252G/G homozygotes. Moreover, TNF-beta levels in stimulated PBMC culture supernatants were negatively correlated with those of IL-4, IL-10 and TGF-beta1. It is possible that TNF-beta plays a modulatory role in the expression of these 3 cytokines. CONCLUSION: TNF-beta +252A polymorphism, other than TNF-alpha, IL-4, IL-10, and TGF-beta1, is significantly associated with SLE in Taiwan.

The interleukin-1 RN polymorphism and Helicobacter pylori infection in the development of duodenal ulcer.

BACKGROUND: The host genetic factors that determine the clinical outcomes for Helicobacter pylori-infected individuals remain unclear. AIMS: To elucidate the relations among interleukin-1 locus polymorphisms, and H. pylori infection in the development of duodenal ulcers. MATERIALS AND METHODS: In a case-control study involving 168 control subjects and 147 patients with duodenal ulcer, biallelic polymorphisms of two interleukin-1 loci, IL-1B(-511) and IL-1B(+3954), as well as the penta-allelic variable number of tandem repeats of interleukin-1 receptor antagonist IL-1RN, were genotyped, and the H. pylori states of controls and patients were examined. RESULTS: Helicobacter pylori infection, male gender and the carriage of IL-1RN*2 independently increased the risk of duodenal ulcer with odds ratios of 6.4 (95% confidence interval, 3.7-11.0), 1.9 (95% confidence interval, 1.1-3.4) and 2.7 (95% confidence interval, 1.1-6.8), respectively. Statistical analysis revealed an interaction between IL-1RN*2 and H. pylori infection with the duodenal ulcer risk conferred by the H. pylori infection substantially increased (odds ratios, 22.6; 95% confidence interval, 5.9-86.5) by the carriage of IL-1RN*2. In addition, a synergistic interaction between IL-1RN*2 and blood group O existed. The combined risk of H. pylori infection, the carriage of IL-1RN*2 and blood group O for duodenal ulcer was 27.5 (95% confidence interval, 3.1-243.6). CONCLUSIONS: This work is the first to verify IL-1RN*2 as an independent factor that governs the development of duodenal ulcers. Our data indicate that H. pylori infection and IL-1RN*2 synergistically determine susceptibility to duodenal ulcer. The blood group phenotype is possibly a crucial determinant for the outcome of the impact of an interleukin-1 locus polymorphism on H. pylori-infected individuals.

Single-nucleotide polymorphisms of transforming growth factor-beta1 gene in Taiwanese patients with systemic lupus erythematosus.

Transforming growth factor-beta1 (TGF-beta1) is involved in the generation of CD8+ T suppressor cells, natural killer (NK) cells and regulatory T (Th3) cells for down-regulatory effects on antibody production. We studied TGF-beta1 activity in patients with systemic lupus erythematosus (SLE) to try to clarify whether the dysregulation by TGF-beta1 is genetically determined. Sera from 55 patients with clinically inactive SLE, who were taking minimal steroids and/or hydroxychloroquine, and 40 healthy controls, along with supernatants from concanavalin A-stimulated peripheral blood mononuclear cell (PBMC) cultures from 18 patients with SLE and 10 controls were subjected to TGF-beta1 enzyme-linked immunosorbent assay. A total of 138 patients with SLE and 182 controls were genotyped for 5 single-nucleotide polymorphisms (SNPs) of TGF-beta1: -988C/A, -800G/A, -509C/T, Leu10/Pro10 and Arg25/Pro25. Patients with SLE had lower serum levels of TGF-beta1 compared with controls (p=0.052). The unstimulated and stimulated TGF-beta1 production of PBMCs in patients with SLE was higher than in controls, although these differences did not reach significance (p=0.073 and 0.074, respectively). None of the TGF-beta1 SNPs was strongly associated with SLE in Taiwanese patients or had any prognostic significance in lupus nephritis. Hence these polymorphisms do not represent a genetic predisposition to SLE. The intrinsic capability of immunoregulation for spontaneous B cell hyperactivity through PBMC TGF-beta1 production was presumed to be intact in clinically stable SLE in Taiwanese. Whether the lower serum TGF-beta1 level that causes the defective immune regulation in SLE is primarily under genetic control or secondary to the influence of ongoing cellular interactions in the cytokine context needs to be elucidated.