Tumor necrosis factor-related apoptosis-inducing ligand translates neonatal respiratory infection into chronic lung disease

Respiratory infections in early life can lead to chronic respiratory disease. Chlamydia infections are common causes of respiratory disease, particularly pneumonia in neonates, and are linked to permanent reductions in pulmonary function and the induction of asthma. However, the immune responses that protect against early-life infection and the mechanisms that lead to chronic lung disease are incompletely understood. Here we identify novel roles for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in promoting Chlamydia respiratory infection-induced pathology in early life, and subsequent chronic lung disease. By infecting TRAIL-deficient neonatal mice and using neutralizing antibodies against this factor and its receptors in wild-type mice, we demonstrate that TRAIL is critical in promoting infection-induced histopathology, inflammation, and mucus hypersecretion, as well as subsequent alveolar enlargement and impaired lung function. This suggests that therapeutic agents that target TRAIL or its receptors may be effective treatments for early-life respiratory infections and associated chronic lung disease.     

Tumor necrosis factor-related apoptosis-inducing ligand promotes migration of human bone marrow multipotent stromal cells

Adult multipotent stromal cells (MSCs), also known as mesenchymal stem cells, represent an important source of cells for the repair of a number of damaged tissues. Both bone marrow (BM)-derived and amniotic MSCs expressed detectable surface levels of two (tumor necrosis factor-related apoptosis-inducing ligand receptor 2 [TRAIL-R2] and TRAIL-R4) of four transmembrane TRAIL receptors. Although the best-characterized activity of TRAIL-R2 is the transduction of apoptotic signals, neither recombinant TRAIL (rTRAIL) nor infection with an adenovirus-expressing TRAIL induced cytotoxic effects on MSCs. Moreover, whereas rTRAIL did not affect proliferation or differentiation of MSCs along the osteogenic and adipogenic lineages, it significantly promoted the migration of human MSCs in range of concentrations comparable to that of soluble TRAIL in human plasma (100 pg/ml). Since rTRAIL induced the rapid phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in MSC cultures and pretreatment with pharmacological inhibitors of the ERK1/2 pathway efficiently counteracted the rTRAIL-induced human MSC migration, these data indicate that ERK1/2 is involved in mediating the ability of rTRAIL to stimulate MSC migration. Taking into consideration that the soluble factors able to induce MSC migration have not been extensively characterized, our current data indicate that the TRAIL/TRAIL-R system might play an important role in the biology of MSCs. Disclosure of potential conflicts of interest is found at the end of this article.     

Involvement of tumor necrosis factor-related apoptosis-inducing ligand and tumor necrosis factor-related apoptosis-inducing ligand receptors in viral hepatic diseases

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in tumor cells, but not in most normal cells. The role of TRAIL in hepatic cell death and hepatic diseases is not well understood. The present study investigated the expression of TRAIL and TRAIL receptors (TRAIL-Rs) in patients with hepatitis C virus infection using immunohistochemistry and examined physiological roles under viral infection in the HepG2 cell line. Staining of TRAIL or TRAIL-Rs was prominent in the cytoplasm and membrane of hepatocytes in the periportal area. Some liver-infiltrating lymphocytes also displayed positive staining for TRAIL. Staining intensity was significantly increased with disease progression, particularly in the periportal area. AdCMVLacZ (Q-BIOgene, Carisbad, Calif) infection was also found to induce apoptosis in HepG2 cells and significantly augment TRAIL-induced apoptosis. Anti-TRAIL antibody significantly inhibited apoptosis induced by AdCMVLacZ infection. Flow cytometry analysis revealed that both TRAIL-R2 and TRAIL were up-regulated on the cell surface of HepG2 cells with AdCMVLacZ infection. Transforming growth factor-beta1 also enhanced TRAIL expression in HepG2 cells. These results indicate that TRAIL/TRAIL-R apoptotic pathways play important roles in the hepatic cell death during viral infection.     

Tumor necrosis factor-related apoptosis-inducing ligand can induce apoptosis in subsets of premalignant cells

During the transformation from a normal to a malignant cell, several mutations are required to bypass the pathways responsible for controlling proliferation. Premalignant cells have acquired some, but not all of these mutations and consequently have not yet attained a malignant phenotype characterized by tumor formation in vivo. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in malignant cells while sparing normal ones and is currently being considered as adjuvant therapy for various human malignancies. Whether TRAIL is effective in inducing apoptosis in premalignant cells is unclear, however. We studied the effect of TRAIL on two human premalignant cell lines the SV7tert and HA1E cells. Both cell lines had been immortalized by the addition of simian virus 40 large T antigen and the telomerase subunit hTERT, but had not been transformed into malignant cells. TRAIL initiated apoptosis by activating both the mitochondrial-independent and -dependent apoptotic pathways in both cell lines at relatively low doses whereas it had no effect on normal human pulmonary artery smooth muscle cells even at high doses. These results suggest that TRAIL can induce apoptosis in premalignant cells and suggests a novel therapy for the treatment of premalignant lesions in vivo.     

肿瘤坏死因子相关凋亡诱导配体参与雷帕霉素诱导血管内皮细胞功能损伤的体外研究

目的: 探讨雷帕霉素对内皮细胞凋亡和增殖、迁移能力的影响,以及肿瘤坏死因子相关凋亡诱导配体(TRAIL)表达水平的变化。方法: 用浓度为0、1、10、100 μg/L 的雷帕霉素孵育内皮细胞24 h,应用CCK8法检测血管内皮细胞的增殖能力,Transwell小室和划痕试验检测细胞迁移能力,DAPI染色观察凋亡细胞核形态改变,Western blotting法检测caspase-3活性以显示血管内皮细胞的凋亡,并用 Western blotting检测TRAIL在凋亡的内皮细胞中的表达。结果: 雷帕霉素(1-100 μg/L)能诱导血管内皮细胞凋亡并抑制其迁移能力(P<0.01)。除雷帕霉素1 μg/L外, 10 μg/L和100 μg/L雷帕霉素均能抑制内皮细胞增殖能力(P<0.01),同时雷帕霉素(10-100 μg/L)使TRAIL蛋白表达增加,两者作用均呈浓度依赖性(P<0.01)。结论: 雷帕霉素能诱导内皮细胞发生凋亡并抑制其增殖和迁移能力。TRAIL表达上调与雷帕霉素诱导血管内皮细胞损伤有一定的相关性。     

Tumor necrosis factor-related apoptosis-inducing ligand mediates the resolution of allergic airway inflammation induced by chronic allergen inhalation

Allergic asthma can vanish over time either spontaneously or induced by allergen-specific immunotherapy. In mice with established airway allergic inflammation, chronic intranasal (IN) allergen challenges decreases progressively airway allergic inflammation. Here we compared the contribution of different regulatory pathways that could be associated with this phenomenon, known as local inhalational tolerance. We found that inhalational tolerance was not associated with increased number of regulatory T cells or suppressive cytokines. Instead, it was associated with increased apoptosis of airway inflammatory leukocytes revealed by annexin-V staining and the expression of apical caspase 8 and effector caspase 3. Also, the transition from acute to chronic phase was associated with a shift in the expression of pro-allergic to pro-apoptotic molecules. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was found to be a key molecule in mediating resolution of allergic inflammation because anti-TRAIL treatment blocked apoptosis and increased the infiltration of T helper type 2 (Th2) cells and eosinophils. Notably, repeated IN treatment with recombinant TRAIL in established airway allergic inflammation augmented leukocyte apoptosis and decreased the frequency of interleukin-5-producing Th2 cells and eosinophils to airways. Our data indicate that TRAIL signaling is sufficient for downmodulation of allergic airway disease, suggesting a potential therapeutic use of TRAIL for asthma treatment.     

Functional expression of tumor necrosis factor-related apoptosis-inducing ligand in human colonic adenocarcinoma cells

TNF-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in various transformed cell lines. Therefore, we investigated TRAIL sensitivity, TRAIL-induced nuclear factor-kappaB (NF-kappaB) activation, and expression of TRAIL in human colonic adenocarcinoma cell lines (HT-29, LS180, SK-CO-1). All four TRAIL receptors (TRAIL-R1 through TRAIL-R4) are expressed in these cell lines. TRAIL sensitivity was assessed by assay of cell viability. Cancer cell viabilities were 83 +/- 3.1% (HT-29), 90 +/- 4.3% (LS180), and 88 +/- 6.3% (SK-CO-1) at 24 hours after the addition of 100 ng/ml TRAIL, indicating that these cell lines were relatively resistant to TRAIL. Activation of NF-kappaB was variably influenced by TRAIL administration, with no consistent tendency among the cell lines, indicating that TRAIL-induced NF-kappaB activation might be cell-type dependent. In contrast, TRAIL was expressed in the human colonic adenocarcinoma cell lines by Western blotting and RT-PCR. Increased expression of TRAIL on tumor cells was observed by flow cytometry after cytokine stimulation (IFN-gamma, TNF-alpha) or the addition of chemotherapeutic agents (camptothecin, doxolubicin hydrochloride). TRAIL on HT-29 cells was functional and able to induce apoptosis in Jurkat cells. Jurkat cell viability was increased by the addition of TRAILR1-R4-Fc. In the presence of various cytokines or chemotherapeutic agents, functional TRAIL is expressed on the surface of tumor cells, and this expressed TRAIL might contribute to tumor immune privilege by inducing apoptosis of activated human lymphocytes.     

Tumor necrosis factor-related apoptosis-inducing ligand and chemotherapy cooperate to induce apoptosis in mesothelioma cell lines

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in certain tumor cells. In addition, TRAIL and chemotherapy can act cooperatively, possibly as a result of chemotherapy-induced increases in expression of a TRAIL receptor, DR5. We used cell lines derived from a highly chemoresistant tumor, malignant mesothelioma, to learn whether TRAIL was effective alone or together with chemotherapy and whether cooperativity depended on increases in DR5 expression. TRAIL (codons 95-285) was expressed in a bacterial expression vector and purified by nickel affinity chromatography. TRAIL alone (25 to 500 ng/ml) had little effect on mesothelioma cells. TRAIL plus chemotherapy (doxorubicin, cis-platinum, etoposide, or gemcitabine) acted cooperatively to induce apoptosis in mesothelioma cells (M28, REN, VAMT, and MS-1). For example, in M28 cells treated for 18 h, apoptosis from TRAIL (100 ng/ml) plus doxorubicin (0.6 microg/ml; 71 +/- 11%) greatly exceeded that from TRAIL alone (21 +/- 8%) or from doxorubicin alone (6 +/- 2%) (means +/- standard deviation; P < 0.03). Mesothelioma cells treated with chemotherapy showed no change in DR5 protein by Western analysis or by immunocytochemistry. TRAIL plus chemotherapy was associated with an increase in mitochondrial cytochrome c release and mitochondrial depolarization. We conclude that TRAIL and chemotherapy act cooperatively to kill mesothelioma cell lines, not by increases in DR5 receptor but in association with mitochondrial amplification of apoptotic signals.     

Influenza-induced expression of functional tumor necrosis factor-related apoptosis-inducing ligand on human peripheral blood mononuclear cells

The immunologic response to influenza virus infection, like many other viruses, is characterized by robust production of proinflammatory cytokines, including type I and II interferon (IFN), which induce a number of antiviral effects and are essential for priming the innate and adaptive cellular components of the immune response. Here, we demonstrate that influenza virus infection induces the expression of functional tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on human peripheral blood mononuclear cell (PBMC) populations. Consistent with previous studies examining TRAIL upregulation, increased TRAIL expression correlated with increased type I and II IFN levels in PBMC cultures. Interestingly, dilution of these cytokines resulted in decreased expression of TRAIL. TRAIL upregulation was not dependent on active viral infection, and TRAIL was observed on NS-1-negative cells. Furthermore, influenza virus infection of lung adenocarcinoma cells (A549) resulted in increased sensitization to TRAIL-induced apoptosis compared with uninfected A549. Infected PBMC expressing TRAIL preferentially killed infected A549, but did not affect uninfected cells, and the addition of soluble TRAIL-R2:Fc blocked the lysis of infected cells, demonstrating TRAIL-dependent killing of infected cells. Collectively, these data demonstrate that TRAIL expression is induced on primary human innate and adaptive immune cells in response to cytokines produced during influenza infection and that TRAIL sensitivity is increased in influenza virus-infected cells. These data also suggest that TRAIL is a primary mechanism used by influenza-stimulated human PBMC to kill influenza-infected target cells and reinforce the importance of cytokines produced in response to TLR agonists in enhancing cellular immune effector functions.     

Histological expression of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in human primary melanoma

AIMS: Tumour necrosis factor-related apoptosis ligand (TRAIL) appears to selectively induce apoptosis in a wide range of cultured malignant cells, including melanoma. This study was designed to attempt to clarify the role of TRAIL in the biology of human melanoma. METHODS: Tissue sections cut from formalin-fixed, paraffin-embedded tissue blocks of 45 primary cutaneous melanomas were tested for expression of TRAIL using immunohistochemistry. The intensity, pattern of staining and percentage of positively stained tumour cells were evaluated in each melanoma. Breslow thickness, ulcerative state, dermal mitotic rate and the presence of tumour infiltrating lymphocytes were measured/determined in each case. Median follow up for the cohort of patients was 10 months (range 1-18). Survival analysis was conducted using the Kaplan-Meier method. The level of expression of TRAIL was compared with the various histological determinants using the two-tailed Fisher's exact test and the chi2-test. RESULTS: Overall and disease-free survival were 72 and 48%, respectively, and did not correlate with TRAIL expression. Among the pathological prognostic determinants, only mitotic rate showed a statistically significant correlation with TRAIL expression using the chi2-test (P=0.04). CONCLUSION: We conclude that TRAIL expression in melanoma defines a more aggressive/proliferative phenotype, either through selection of apoptotic resistant cells or by secondary induction of other factors enhancing proliferation of more malignant cells. Analysis of a larger group of patients with longer follow-up is required to determine whether TRAIL expression correlates with survival of patients.     

Cleavage of p53-vimentin complex enhances tumor necrosis factor-related apoptosis-inducing ligand-mediated apoptosis of rheumatoid arthritis synovial fibroblasts

Rheumatoid arthritis synovial fibroblasts (RASFs) contribute to arthritic cartilage degradation. Although RASFs are normally resistant to apoptosis, Apo2L/tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-based gene therapy has been successfully used in a mouse model of arthritis. We investigated this further by treating human RASFs with nontoxic doses of the proteasome inhibitor lactacystin. Treatment induced cytosolic accumulation of p53 and enhanced the susceptibility of RASFs to apoptosis mediated by TRAIL-R2 (DR5) but not Fas. A specific role for p53 in TRAIL-R2-mediated apoptosis was indicated by the ability of p53 siRNA to significantly reduce RASF apoptosis and by the reduced apoptosis of RASFs bearing p53 mutations on treatment with anti-DR5 antibody or anti-DR5 antibody plus lactacystin. p53 immunoprecipitation followed by mass spectrometry identified a vimentin-p53 complex, an interaction that was confirmed by reciprocal vimentin-p53 immunoprecipitation and by co-immunofluorescence. Interestingly, human caspase-4 cleaved human vimentin, and blockade of caspase-4 with a chemical inhibitor or with specific siRNA significantly inhibited TRAIL-R2-mediated apoptosis of RASFs. Furthermore, blockade of caspase-4 was paralleled by persistence of a cytosolic pattern of p53 and absence of p53 translocation to the nucleus. Taken together, our findings suggest a unique role for caspase-4 in cleaving vimentin and releasing cytosolic p53 for nuclear translocation, events that may regulate the sensitivity of RASFs to receptor-mediated apoptosis.     

Current understanding on the immunological functions of tumor necrosis factor-related apoptosis-inducing ligand

Tumor necrosis factor （TNF）-related apoptosis-inducing ligand （TRAIL） selectively induces apoptosis in various tumor cells and virus-infected cells, but rarely in normal cells. The killing specificity of TRAIL has brought great interests to develop a novel apoptosis-based anti-tumor agent for clinical application. TRAIL is expressed in many normal tissues and cells, such as liver, brain, kidney, heart, colon, lung, and testis. However, immunological and physiological functions of TRAIL in vivo have not been understood well. In the present paper we summarized the progress in the research on immunological functions of TRAIL.     

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in central nervous system inflammation

In a wide variety of acute and chronic central nervous system (CNS) disorders, inflammatory processes contribute to the damage of brain cells and progression of the disease. Along with other regulatory cytokines, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is involved in the pathology of multiple sclerosis (MS) and murine experimental autoimmune encephalomyelitis (EAE), bacterial meningitis (BM), HIV encephalitis (HIVE), stroke and Alzheimer's disease (AD). In these conditions, TRAIL is released within the brain mainly by activated microglia and leukocytes infiltrating from the blood stream. TRAIL promotes apoptosis of parenchymal cells in MS/EAE, HIVE, AD and stroke through interaction with TRAIL death receptors expressed on these cells. Frequently, cells in the diseased brain display increased susceptibility to apoptosis induction by TRAIL due to upregulation of death receptors and downregulation of decoy receptors. On the other hand, TRAIL inhibits the proliferation of encephalitogenic T cells in EAE, and it is involved in the clearance of infected brain macrophages in HIVE and of activated neutrophils in BM by interaction with their death receptors. Especially in BM, the ability of TRAIL to limit an acute granulocyte-driven inflammation carries significant neuroprotective potential. Given the diversity of beneficial and harmful effects in the immune and nervous system, TRAIL is a double-edged sword in diseases involving CNS inflammation.     

Regulation of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and TRAIL receptor expression in human neutrophils

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily, which is capable of inducing apoptosis in many cell types, including tumour and virus-infected cells, but rarely in normal cells. Expression of TRAIL mRNA and TRAIL receptors has previously been detected in neutrophils; however, the expression of TRAIL protein and the regulation of TRAIL and TRAIL receptor expression in these cells remain unknown. Here we report, for the first time, that neutrophils constitutively express TRAIL protein on their cell surface and that the TRAIL protein is shed during culture. TNF-alpha is a down-regulator of TRAIL expression, whereas IFN-gamma up-regulates the expression of TRAIL. Neutrophils did not express a detectable level of TRAIL-R1 or -R4, but constitutively expressed a low, but substantial, level of TRAIL-R2 and a high level of TRAIL-R3. Although the level of TRAIL-R2 was not significantly altered during culture under different experimental conditions, approximately 30% of TNF-alpha-treated cells rapidly lost their high-level TRAIL-R3 expression, whereas the majority of IFN-gamma-treated cells retained a high level of TRAIL-R3 expression. Anti-TRAIL neutralizing antibody significantly inhibited neutrophil apoptosis during cultures in medium alone, or in the presence of TNF-alpha or IFN-gamma. Thus, our study identified human neutrophils as a cellular source of TRAIL and suggests that neutrophil-derived TRAIL may play a role in immune surveillance. Our results also suggest a role for the TRAIL/TRAIL receptor system in neutrophil apoptosis.     

Staphylococcus aureus and Salmonella enterica serovar Dublin induce tumor necrosis factor-related apoptosis-inducing ligand expression by normal mouse and human osteoblasts

Staphylococcus aureus and Salmonella enterica serovar Dublin invade osteoblasts and are causative agents of human bone disease. In the present study, we examined the ability of S. aureus and Salmonella serovar Dublin to induce the production of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) by normal osteoblasts. Normal mouse and human osteoblasts were cocultured with S. aureus or Salmonella serovar Dublin at different multiplicities of infection. Following initial incubation and examination of TRAIL expression, extracellular bacteria were killed by the addition of media containing the antibiotic gentamicin. Lysates and conditioned media from osteoblast cultures were then collected at various times following invasion and analyzed. The results demonstrated that S. aureus and Salmonella serovar Dublin are potent inducers of TRAIL expression by osteoblasts. Mouse and human TRAIL mRNA expression was induced by bacterial infection and demonstrated a dose-dependent response. Analysis of kinetics suggested that TRAIL mRNA was induced within 30 min after exposure to bacteria and that its level of expression remained relatively constant over the time period examined. mRNA molecules encoding TRAIL receptors were constitutively expressed by osteoblasts. Furthermore, TRAIL protein was detected as early as 45 min and up to 24 h following infection. The quantity of TRAIL protein produced also increased in a dose-dependent manner. Collectively, these findings suggest a mechanism whereby bacterial pathogens mediate bone destruction via osteoblast apoptosis.     

A pathogenic role for tumor necrosis factor-related apoptosis-inducing ligand in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a life-threatening inflammatory respiratory disorder, often induced by cigarette smoke (CS) exposure. The development of effective therapies is impaired by a lack of understanding of the underlining mechanisms. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine with inflammatory and apoptotic properties. We interrogated a mouse model of CS-induced experimental COPD and human tissues to identify a novel role for TRAIL in COPD pathogenesis. CS exposure of wild-type mice increased TRAIL and its receptor messenger RNA (mRNA) expression and protein levels, as well as the number of TRAIL⁺CD11b⁺ monocytes in the lung. TRAIL and its receptor mRNA were also increased in human COPD. CS-exposed TRAIL-deficient mice had decreased pulmonary inflammation, pro-inflammatory mediators, emphysema-like alveolar enlargement, and improved lung function. TRAIL-deficient mice also developed spontaneous small airway changes with increased epithelial cell thickness and collagen deposition, independent of CS exposure. Importantly, therapeutic neutralization of TRAIL, after the establishment of early-stage experimental COPD, reduced pulmonary inflammation, emphysema-like alveolar enlargement, and small airway changes. These data provide further evidence for TRAIL being a pivotal inflammatory factor in respiratory diseases, and the first preclinical evidence to suggest that therapeutic agents that target TRAIL may be effective in COPD therapy.     

Monocytes stimulated with group B streptococci or interferons release tumour necrosis factor-related apoptosis-inducing ligand

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a cytotoxic member of the TNF family. Some reports have shown that TRAIL is released from cells in a soluble form. In this work, we have investigated the mechanism of release of TRAIL from monocytes. First, we show that whole gram-positive, gram-negative and mycoplasmal bacteria as well as lipopolysaccharide (LPS), interferon-alpha (IFN-alpha), -beta and -gamma all induced upregulation of TRAIL on the surface of human monocytes. Next, we show that IFN-alpha, -beta and -gamma all induced a dose-dependent release of TRAIL, giving significant amounts of soluble TRAIL after 2 days. Of the bacteria, only the Group B streptococcus COH-1 (GBS) induced release of TRAIL and concomittantly induced IFN-alpha. Monocytes stimulated with GBS or IFN-alpha also showed extensive cell death. When monocyte apoptosis was prevented by interleukin-1, GM-CSF, LPS or the caspase inhibitor zVADfmk, the IFN-alpha-induced release of TRAIL was reduced, whereas agents inducing necrosis caused increased release of TRAIL. LPS also prevented release of TRAIL from GBS-stimulated monocytes. The release of TRAIL from IFN-alpha-stimulated monocytes was reduced by inhibitors of both cysteine and metalloproteases. We conclude that bacteria and IFN induce upregulation of membrane TRAIL and that release of TRAIL is associated with cell death.     

Identification of the mycobacterial subcomponents involved in the release of tumor necrosis factor-related apoptosis-inducing ligand from human neutrophils

Intravesical administration of Mycobacterium bovis bacillus Calmette-Guérin (BCG) continues to be a successful immunotherapy for superficial bladder cancer. Recently, workers in our laboratory observed expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on neutrophils in voided urine following BCG therapy. Neutrophils released a soluble and functional form of TRAIL when they were stimulated in vitro with BCG, and the activity was localized predominantly to the cell wall fraction. In this study, we examined the ability of individual mycobacterial components to stimulate TRAIL release from neutrophils. Our results demonstrated that cell wall-derived lipoarabinomannan (LAM), mycolyl arabinogalactan-peptidoglycan complex, and a Triton X-114 (Tx114)-solubilized protein pool were effective agonists of TRAIL release from neutrophils. Mycobacterial DNA was also an agonist of TRAIL release from neutrophils. Furthermore, purified antigen 85 ABC complex and alpha-crystallin (HspX), two major cell wall antigens present in the Tx114 pool, induced TRAIL release from neutrophils. The Tx114 pool stimulated HEK-293 cells expressing either Toll-like receptor 2/1 (TLR2/1) or TLR2/6, but only HspX was able to stimulate TLR2/6-expressing cells. TLR4/MD2/CD14-expressing cells responded only to LAM. Collectively, these results suggested that TRAIL release from neutrophils was induced through the recognition of multiple mycobacterial components by TLR2 and TLR4.     

Adrenomedullin suppresses tumour necrosis factor alpha-induced CXC chemokine ligand 10 production by human gingival fibroblasts

Periodontal disease is an inflammatory disorder characterized by the involvement of chemokines that are important for the recruitment of leucocytes. Several cytokines, including tumour necrosis factor alpha (TNF-alpha), are involved in regulating levels of chemokines in periodontal disease. CXC chemokine ligand 10 (CXCL10) is a chemokine related to the migration of T helper 1 cells. In this study, we examined CXCL10 expression in human gingival fibroblasts (HGFs). Moreover, we investigated the effects of adrenomedullin (AM), which is a multi-functional regulatory peptide, on the production of CXCL10 by HGFs. We revealed that TNF-alpha stimulation induced CXCL10 production by HGFs. HGFs expressed AM and AM receptors, calcitonin-receptor-like receptor (CRLR) and receptor-activity-modifying protein (RAMP) 2, mRNAs constitutively. AM treatment supressed CXCL10 production by TNF-alpha-stimulated HGFs. Moreover, we elucidated that AM produced by HGFs inhibited CXCL10 production by HGFs, because AM antagonist enhanced CXCL10 production by HGFs. TNF-alpha treatment enhanced CRLR and RAMP2 mRNA expression in HGFs. Furthermore, AM is expressed in human periodontal tissues, including both inflamed and clinically healthy tissues. These results suggest that the CXCL10 produced by HGFs may be involved in the migration of leucocytes into inflamed tissues and related to exacerbation of periodontal disease. AM might be a therapeutic target of periodontal disease, because AM can inhibit CXCL10 production by HGFs.