A Proliferation-Inducing Ligand Regulation in Polymorphonuclear Neutrophils by Panax ginseng.

A proliferation-inducing ligand (APRIL) is a member of the tumor necrosis factor superfamily that was first identified as a factor favoring tumorigenesis. APRIL is important fitness and survival factors for B cells and plasma cells in the periphery. Considering this, as well as the quantitative predominance of neutrophils among the peripheral blood leukocytes, we carried out the first study assessing the influence of the transforming growth factor (TGF)-ß signaling pathway on APRIL expression in these cells. Furthermore, as the Rb1 ginsenoside is known to exhibit multiple pharmacological activities, we verified if the saponin is capable of modulating the process. The present study shows that TGF-ß increased the expression of APRIL and the level of phospho-p38, phospho-Akt(T308), and phospho-Akt(S473) in the cytoplasmic fraction, as well as the expression of Fra1, c-Fos, and c-Jun in the nuclear fraction, of neutrophils. However, exposure of these cells to Rb1 reduced the expression and level of the investigated proteins. No changes were found in the expression of APRIL and the level of p-p38 in the cytoplasmic fraction of neutrophils following the application of Rb1 alone, as well as in the neutrophils incubated first with Rb1 and then with TGF-ß, whereas a higher level of phosphorylation was observed for Akt and PI3 kinases in the cells. Moreover, a higher expression of all the studied transcription factors was observed in the nuclear fraction of neutrophils. Based on the observed changes, it may be assumed that the expression of APRIL molecule in TGF-ß-induced neutrophils and its regulation by Rb1 are associated with PI3K/AKT signaling pathways and transcription factors Fra-1, Fra-2, c-Jun, and c-Fos. Rb1 appears to be a favorable factor that may be potentially used in the modulation of tumor-promoting APRIL expression.

Inhibitors of elastase stimulate murine B lymphocyte differentiation into IgG- and IgA-producing cells.

It is well established that dendritic cells and macrophages play a role in antigen presentation to B and T cells and in shaping B and T cell responses via cytokines they produce. We have previously reported that depletion of neutrophils improves the production of mucosal IgA after sublingual immunization with Bacillus anthracis edema toxin as adjuvant. These past studies also demonstrated that an inverse correlation exists between the number of neutrophils and production of IgA by B cells. Using specific inhibitors of elastase, we addressed whether the elastase activity of neutrophil could be the factor that interferes with production of IgA and possibly other immunoglobulin isotypes. We found that murine splenocytes and mesenteric lymph node cells cultured for 5 days in the presence of neutrophil elastase inhibitors secreted higher levels of IgG and IgA than cells cultured in the absence of inhibitors. The effect of the inhibitors was dose-dependent and was consistent with increased frequency of CD138+ cells expressing IgG or IgA. Finally, neutrophil elastase inhibitors increased transcription of mRNA for AID, IL-10, BAFF and APRIL, factors involved in B cell differentiation. These findings identify inhibitors of elastase as potential adjuvants for increasing production of antibodies.

Effect of glucocorticoid treatment on BAFF and APRIL expression in patients with immune thrombocytopenia (ITP).

Immune thrombocytopenic purpura (ITP) is an idiopathic bleeding disorder. B cell activating factor (BAFF) and 'A proliferation-inducing ligand' (APRIL) have regulatory effects on B and T cells and may represent relevant factors in the pathogenesis of ITP. Serum levels and gene expression were investigated in ITP patients. Both BAFF and APRIL serum levels were significantly elevated in active ITP. However, gene expression analysis revealed both factors to have a tendency toward downregulation. Glucocorticoid treatment significantly reduced BAFF but not APRIL serum levels, which may be mediated by differences in transcription factor binding sites. The glucocorticoid receptor binding site is present in the BAFF promotor region, but not in the APRIL promotor region. Prednisolone in combination with vitamin D3 may be effective in reducing APRIL serum levels. In conclusion, glucocorticoid treatment exerts different regulatory effects on both BAFF and APRIL, whereas antioxidant supplementation may also be beneficial in reducing serum levels.

Synergisic effect of APRIL knockdown and Jiedu Xiaozheng Yin, a Chinese medicinal recipe, on the inhibition of hepatocellular carcinoma cell proliferation.

It is well documented that A proliferation-inducing ligand (APRIL), a member of the tumor necrosis factor superfamily, plays a crucial role in the occurrence and development of tumors. In the present study, we evaluated the synergistic effect of APRIL knockdown and Jiedu Xiaozheng Yin (JXY), a Traditional Chinese Medicinal recipe, on the inhibition of hepatocellular carcinoma (HCC) cell proliferation and elucidated the underlying mechanism. The results demonstrated that both APRIL knockdown using small interfering RNA (siRNA) and JXY treatment could trigger cell cycle arrest and cell apoptosis, and suppress HCC cell proliferation through an NF-κB-related pathway. Synergism was further demonstrated between APRIL knockdown and JXY treatment. In conclusion, these results indicate that APRIL is a target gene for HCC and combination of siRNA-APRIL and JXY application holds great promise as a novel approach for the treatment of APRIL-positive HCC.

Amelioration of colorectal cancer using negative lipidoid nanoparticles to encapsulate siRNA against APRIL by enema delivery mode.

A proliferation-inducing ligand (APRIL) is a key cell proliferation-regulatory molecule and have been investigated well enough in immunity regulation and a few of immune diseases. APRIL can stimulate tumor cell growth and is up-expressed in cancer tissues, especially in CRC (colorectal cancer). However, whether inhibition of APRIL can regulate tumor-relative genes expression in vivo and subsequently ameliorate the pathological progress of CRC remains obscure. To address this question, we developed a novel negative lipidoid nanoparticles (NLNs) encapsulating small interference RNA (siRNA) for selectively silencing APRIL in the parenchyma of CRC focus in vivo, which uptake proceeded through a lipid raft endocytotic pathway. Local enema delivery of APRIL-NLNs silenced APRIL in CRC cells and animal models, and then ameliorated experimentally the progress of CRC by suppressing CRC cell proliferation, metastasis, and apoptosis-related cytokine expression and did not affect the function of liver and kidneys and not trigger the immune response of CRC models. This study reveals APRIL to be a potential anti-CRC target by in vivo experiments, and suggests that the application of similar modes of siRNA delivery may be feasible in other therapeutic settings.

Oral-nasopharyngeal dendritic cells mediate T cell-independent IgA class switching on B-1 B cells.

Native cholera toxin (nCT) as a nasal adjuvant was shown to elicit increased levels of T-independent S-IgA antibody (Ab) responses through IL-5- IL-5 receptor interactions between CD4+ T cells and IgA+ B-1 B cells in murine submandibular glands (SMGs) and nasal passages (NPs). Here, we further investigate whether oral-nasopharyngeal dendritic cells (DCs) play a central role in the induction of B-1 B cell IgA class switch recombination (CSR) for the enhancement of T cell-independent (TI) mucosal S-IgA Ab responses. High expression levels of activation-induced cytidine deaminase, Iα-Cµ circulation transcripts and Iµ-Cα transcripts were seen on B-1 B cells purified from SMGs and NPs of both TCRß⁻/⁻ mice and wild-type mice given nasal trinitrophenyl (TNP)-LPS plus nCT, than in the same tissues of mice given nCT or TNP-LPS alone. Further, DCs from SMGs, NPs and NALT of mice given nasal TNP-LPS plus nCT expressed significantly higher levels of a proliferation-inducing ligand (APRIL) than those in mice given TNP-LPS or nCT alone, whereas the B-1 B cells in SMGs and NPs showed elevated levels of transmembrane activator and calcium modulator cyclophilin ligand interactor (TACI) expression. Interestingly, high frequencies of IgA+ B-1 B cells were induced when peritoneal IgA⁻ IgM+ B cells were stimulated with mucosal DCs from mice given nasal TNP-LPS plus nCT. Taken together, these findings show that nasal nCT plays a key role in the enhancement of mucosal DC-mediated TI IgA CSR by B-1 B cells through their interactions with APRIL and TACI.

APRIL is a novel clinical chemo-resistance biomarker in colorectal adenocarcinoma identified by gene expression profiling.

BACKGROUND: 5-Fluorouracil(5FU) and oral analogues, such as capecitabine, remain one of the most useful agents for the treatment of colorectal adenocarcinoma. Low toxicity and convenience of administration facilitate use, however clinical resistance is a major limitation. Investigation has failed to fully explain the molecular mechanisms of resistance and no clinically useful predictive biomarkers for 5FU resistance have been identified. We investigated the molecular mechanisms of clinical 5FU resistance in colorectal adenocarcinoma patients in a prospective biomarker discovery project utilising gene expression profiling. The aim was to identify novel 5FU resistance mechanisms and qualify these as candidate biomarkers and therapeutic targets. METHODS: Putative treatment specific gene expression changes were identified in a transcriptomics study of rectal adenocarcinomas, biopsied and profiled before and after pre-operative short-course radiotherapy or 5FU based chemo-radiotherapy, using microarrays. Tumour from untreated controls at diagnosis and resection identified treatment-independent gene expression changes. Candidate 5FU chemo-resistant genes were identified by comparison of gene expression data sets from these clinical specimens with gene expression signatures from our previous studies of colorectal cancer cell lines, where parental and daughter lines resistant to 5FU were compared. A colorectal adenocarcinoma tissue microarray (n = 234, resected tumours) was used as an independent set to qualify candidates thus identified. RESULTS: APRIL/TNFSF13 mRNA was significantly upregulated following 5FU based concurrent chemo-radiotherapy and in 5FU resistant colorectal adenocarcinoma cell lines but not in radiotherapy alone treated colorectal adenocarcinomas. Consistent with APRIL's known function as an autocrine or paracrine secreted molecule, stromal but not tumour cell protein expression by immunohistochemistry was correlated with poor prognosis (p = 0.019) in the independent set. Stratified analysis revealed that protein expression of APRIL in the tumour stroma is associated with survival in adjuvant 5FU treated patients only (n = 103, p < 0.001), and is independently predictive of lack of clinical benefit from adjuvant 5FU [HR 6.25 (95%CI 1.48-26.32), p = 0.013]. CONCLUSIONS: A combined investigative model, analysing the transcriptional response in clinical tumour specimens and cancers cell lines, has identified APRIL, a novel chemo-resistance biomarker with independent predictive impact in 5FU-treated CRC patients, that may represent a target for novel therapeutics.

APRIL (TNFSF13) regulates collagen-induced arthritis, IL-17 production and Th2 response.

A proliferation-inducing ligand (APRIL or TNFSF13) shares receptors with B-cell activation factor of the TNF family (BAFF) on B and T cells. Although much is known about the function of APRIL in B cells, its role in T cells remains unclear. Blocking both BAFF and APRIL suggested that BAFF and/or APRIL contributed to collagen-induced arthritis (CIA); however, the role of APRIL alone in CIA remained unresolved. We show here that, in vitro, our newly generated APRIL(-/-) mice exhibited increased T-cell proliferation, enhanced Th2 cytokine production under non-polarizing conditions, and augmented IL-13 and IL-17 production under Th2 polarizing conditions. Upon immunization with OVA and aluminum potassium sulfate, APRIL(-/-) mice responded with an increased antigen-specific IgG1 response. We also show that in APRIL(-/-) mice, the incidence of CIA was significantly reduced compared with WT mice in parallel with diminished levels of antigen-specific IgG2a autoantibody and IL-17 production. Our data indicate that APRIL plays an important role in the regulation of cytokine production and that APRIL-triggered signals contribute to arthritis. Blockade of APRIL thus may be a valuable adjunct in the treatment of rheumatoid arthritis.