The Effects of Low-dose Ionizing Radiation in the Activated Rat Basophilic Leukemia (RBL-2H3) Mast Cells

Mast cells play important roles in many biological responses, such as those during allergic diseases and inflammatory disorders. Although laser and UV irradiation have immunosuppressive effects on inflammatory diseases by suppressing mast cells, little is known about the effects of γ-ionizing radiation on mast cells. In this study, we investigated the effects of γ-ionizing radiation on RBL-2H3 cells, a convenient model system for studying regulated secretion by mast cells. Low-dose radiation (<0.1 gray (Gy)) did not induce cell death, but high-dose radiation (>0.5 Gy) induced apoptosis. Low-dose ionizing radiation significantly suppressed the release of mediators (histamine, β-hexosaminidase, IL-4, and tumor necrosis factor-α) from immunoglobulin E (IgE)-sensitized RBL-2H3 cells. To determine the mechanism of mediator release inhibition by ionizing radiation, we examined the activation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, PKCs, and MAPK, and intracellular free calcium concentrations ([Ca(2+)](i)). The phosphorylation of signaling molecules following stimulation of high-affinity IgE receptor I (FcεRI) was specifically inhibited by low-dose ionizing radiation (0.01 Gy). These results were due to the suppression of FcεRI expression by the low-dose ionizing radiation. Therefore, low-dose ionizing radiation (0.01 Gy) may function as a novel inhibitor of mast cell activation.     

Apolipoproteins and Apolipoprotein Mimetic Peptides Modulate Phagocyte Trafficking through Chemotactic Activity

The plasma lipoprotein-associated apolipoproteins (apo) A-I and apoE have well described anti-inflammatory actions in the cardiovascular system, and mimetic peptides that retain these properties have been designed as therapeutics. The anti-inflammatory mechanisms of apolipoprotein mimetics, however, are incompletely defined. Whether circulating apolipoproteins and their mimetics regulate innate immune responses at mucosal surfaces, sites where transvascular emigration of leukocytes is required during inflammation, remains unclear. Herein, we report that Apoai^−/− and Apoe^−/− mice display enhanced recruitment of neutrophils to the airspace in response to both inhaled lipopolysaccharide and direct airway inoculation with CXCL1. Conversely, treatment with apoA-I (L-4F) or apoE (COG1410) mimetic peptides reduces airway neutrophilia. We identify suppression of CXCR2-directed chemotaxis as a mechanism underlying the apolipoprotein effect. Pursuing the possibility that L-4F might suppress chemotaxis through heterologous desensitization, we confirmed that L-4F itself induces chemotaxis of human PMNs and monocytes. L-4F, however, fails to induce a calcium flux. Further exploring structure-function relationships, we studied the alternate apoA-I mimetic L-37pA, a bihelical analog of L-4F with two Leu-Phe substitutions. We find that L-37pA induces calcium and chemotaxis through formyl peptide receptor (FPR)2/ALX, whereas its D-stereoisomer (i.e. D-37pA) blocks L-37pA signaling and induces chemotaxis but not calcium flux through an unidentified receptor. Taken together, apolipoprotein mimetic peptides are novel chemotactic agents that possess complex structure-activity relationships to multiple receptors, displaying anti-inflammatory efficacy against innate immune responses in the airway.     

Special AT-rich sequence-binding protein 2 and its related genes play key roles in the differentiation of MC3T3-E1 osteoblast like cells

Special AT-rich sequence-binding protein (SATB) plays a critical role in bone generation and osteoblast differentiation. In the present study, the differentially expressed genes by SATB2 overexpression were analyzed in MC3T3-E1 osteoblast-like cells using Alizarin red S staining, wound healing assay and Agilent's Human Oligo Microarray. Calcium mineralization and motility were significantly enhanced in SATB2-overexpressed cells compared with untreated control. In addition, using the GeneSpringGX 7.3 program to compare the identified genes expressed in SATB2-overexpresed cells with untreated control, we found several unique genes closely associated with osteoblast differentiation, including SOX2, MBP2, WNT11 and MEN1 (up-regulated genes), and ILK, FGF23, FGFR2, and SNAI1 (down-regulated genes). Consistent with microarray data, real-time RT-PCR confirmed the significant up- and down-regulation of these genes at mRNA level in SATB2-overexpressed MC3T3-E1 cells. Overall, our findings suggest that the molecular regulation of SATB2 can be an attractive approach to develop a novel therapeutic strategy for bone-related diseases.     

BAFF induces spleen CD4(+) T cell proliferation by down-regulating phosphorylation of FOXO3A and activates cyclin D2 and D3 expression

The TNF ligand family member "B cell-activating factor belonging to the TNF family" (BAFF, also called BLyS, TALL-1, zTNF-4, and THANK) is an important survival factor for B and T cells. In this study, we show that BAFF is able to induce CD4(+) spleen T cell proliferation when co-stimulated with anti-CD3. Expression of phosphorylated FOXO3A was notably down-regulated and cyclins D2 and D3 were up-regulated and higher in the CD4(+) T cells when treated with BAFF and anti-CD3, as assessed by Western blotting. Furthermore, after FOXO3A was knocked down, expression of cyclin D1 was unchanged, compared with control group levels, but the expression of cyclins D2 and D3 increased, compared with the control group. In conclusion, our results suggest that BAFF induced CD4(+) spleen T cell proliferation by down-regulating the phosphorylation of FOXO3A and then activating cyclin D2 and D3 expression, leading to CD4(+) T cell proliferation.     

Tim-3 pathway controls regulatory and effector T cell balance during hepatitis C virus infection

Hepatitis C virus (HCV) is remarkable at disrupting human immunity to establish chronic infection. Upregulation of inhibitory signaling pathways (such as T cell Ig and mucin domain protein-3 [Tim-3]) and accumulation of regulatory T cells (Tregs) play pivotal roles in suppressing antiviral effector T cell (Teff) responses that are essential for viral clearance. Although the Tim-3 pathway has been shown to negatively regulate Teffs, its role in regulating Foxp3(+) Tregs is poorly explored. In this study, we investigated whether and how the Tim-3 pathway alters Foxp3(+) Treg development and function in patients with chronic HCV infection. We found that Tim-3 was upregulated, not only on IL-2-producing CD4(+)CD25(+)Foxp3(-) Teffs, but also on CD4(+)CD25(+)Foxp3(+) Tregs, which accumulate in the peripheral blood of chronically HCV-infected individuals when compared with healthy subjects. Tim-3 expression on Foxp3(+) Tregs positively correlated with expression of the proliferation marker Ki67 on Tregs, but it was inversely associated with proliferation of IL-2-producing Teffs. Moreover, Foxp3(+) Tregs were found to be more resistant to, and Foxp3(-) Teffs more sensitive to, TCR activation-induced cell apoptosis, which was reversible by blocking Tim-3 signaling. Consistent with its role in T cell proliferation and apoptosis, blockade of Tim-3 on CD4(+)CD25(+) T cells promoted expansion of Teffs more substantially than Tregs through improving STAT-5 signaling, thus correcting the imbalance of Foxp3(+) Tregs/Foxp3(-) Teffs that was induced by HCV infection. Taken together, the Tim-3 pathway appears to control Treg and Teff balance through altering cell proliferation and apoptosis during HCV infection.     

Genome Sequence of Canine Parvovirus Strain SC02/2011, Isolated from a Puppy with Severe Diarrhea in South China

A widespread hemorrhagic gastroenteritis in young dogs occurred in South China. A virulent field canine parvovirus (CPV) strain, SC02/2011, was isolated from a puppy showing enteric signs in Guangdong, China. The genome of CPV strain SC02/2011 was sequenced and analyzed, which will promote a better understanding of the molecular epidemiology and genetic diversity of CPV field isolates in South China.     

The association between the mannose-binding lectin codon 54 polymorphism and systemic lupus erythematosus: a meta-analysis update

The aim of this study was to determine whether the functional mannose-binding lectin (MBL2) exon 1 codon 54 polymorphism (rs1800450) confers susceptibility to systemic lupus erythematosus (SLE) in ethnically different populations. A meta-analysis was conducted on the MBL2 codon 54 polymorphism across 21 comparative studies. Meta-analysis showed an association between the MBL2 codon 54 B allele and SLE in all study subjects [odds ratio (OR) = 1.298, 95% confidence interval (CI) = 1.154–1.459, P = 1.4 × 10⁻⁵]. Analysis after stratification by ethnicity indicated that the MBL2 codon 54 B allele is significantly associated with SLE in Europeans, Asian, and Africans (OR = 1.246, 95% CI = 1.062–1.462, P = 0.007; OR = 1.268, 95% CI = 1.049–1.532, P = 0.014; OR = 1.939, 95% CI = 1.269–2.962, P = 0.002, respectively). However, African Americans had a much lower prevalence of the T allele (5.8%) than any other populations studied, whereas Asians had the highest prevalence (16.2%). This meta-analysis confirms that the MBL2 codon 54 polymorphism is associated with SLE susceptibility in different ethnic groups, and that its prevalence is ethnicity dependent.     

Molecular characterization,recombinant expression in <Emphasis Type="Italic">Escherichia coli</Emphasis> and biological activity of (<Emphasis Type="Italic">S</Emphasis>)-Tetrahydroberberine oxidase from <Emphasis Type="Italic">Corydalis saxicola</Emphasis> Bunt

(S)-Tetrahydroberberine [(S)-THB] oxidase is the last enzyme of benzylisoquinoline alkaloids pathway which catalyzes the dehydrogenation of four hydrogen atoms of (S)-THB to produce berberine, the final step of berberine biosynthesis. A (S)-THB gene, designated as Cs(S)-THBO (Genbank accession No. HQ393909), was cloned from a Corydalis saxicola cDNA library by rapid amplification of cDNA ends. The full-length of cDNA of Cs(S)-THBO was 1127 bp with an open reading frame of 699 bp that predicted to encode a 232-amino acid polypeptide, with a predicted molecular mass of 25.20 kDa. Cs(S)-THBO was the first (S)-THBO gene found in C. saxicola. Real-time quantitative PCR analysis indicated that Cs(S)-THBO was constitutively expressed in roots, stems, leaves and flowers of C. saxicola, and with the highest expression level in roots. The results of treatment experiment for plant defense responses revealed that expression of Cs(S)-THBO had a prominent diversity. Recombinant Cs(S)-THBO protein expressed in Escherichia coli strain BL21 (DE3) was active. The results of feeding experiment and HPLC–DAD–ESI–MSⁿ analysis showed that Cs(S)-THBO had the function of catalyzing (S)-tetrahydroberberine to berberine.