Selective Activation of Human Dendritic Cells by OM-85 through a NF-kB and MAPK Dependent Pathway
Carmen ParolaLaura SalogniXenia VairaSara ScuteraPaolo SommaValentina SalviTiziana MussoGiuseppe TabbiaMarco BardessonoChristian PasqualiAlberto MantovaniSilvano SozzaniDaniela Bosisio
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Abstract:
OM-85 (Broncho-Vaxom®, Broncho-Munal®, Ommunal®, Paxoral®, Vaxoral®), a product made of the water soluble fractions of 21 inactivated bacterial strain patterns responsible for respiratory tract infections, is used for the prevention of recurrent upper respiratory tract infections and acute exacerbations in chronic obstructive pulmonary disease patients. OM-85 is able to potentiate both innate and adaptive immune responses. However, the molecular mechanisms responsible for OM-85 activation are still largely unknown. Purpose of this study was to investigate the impact of OM-85 stimulation on human dendritic cell functions. We show that OM-85 selectively induced NF-kB and MAPK activation in human DC with no detectable action on the interferon regulatory factor (IRF) pathway. As a consequence, chemokines (i.e. CXCL8, CXCL6, CCL3, CCL20, CCL22) and B-cell activating cytokines (i.e. IL-6, BAFF and IL-10) were strongly upregulated. OM-85 also synergized with the action of classical pro-inflammatory stimuli used at suboptimal concentrations. Peripheral blood mononuclear cells from patients with COPD, a pathological condition often associated with altered PRR expression pattern, fully retained the capability to respond to OM-85. These results provide new insights on the molecular mechanisms of OM-85 activation of the immune response and strengthen the rational for its use in clinical settings.Keywords:
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The immune system undergoes profound age-related changes, including a gradual increase in the production and circulation of proinflammatory cytokines. Despite the known capacity of fibroblasts to produce cytokines, little is known so far about the inflammatory response of fibroblasts to cellular stress such as viral and/or bacterial infection in the context of aging. Therefore the aim of this study was to analyze the levels of IL6 and IL8 secretion in supernatants of human skin fibroblasts from young and elderly persons. Cytokine and chemokine secretion was analyzed before and after in vitro infection of the cells with Cytomegalovirus (CMV) and/or stimulation with Lipopolysaccharide (LPS). The exposure of fibroblasts to these agents caused inflammatory changes, reflected by the secretion of both the cytokine IL6 and the chemokine IL8 by fibroblasts from young as well as elderly persons. The cytokine/chemokine production induced by either agent alone could be further increased by co-stimulation of the cells with both stimuli. The level of protein secretion was dependent on the chronological age of the fibroblasts. Stimulated human skin fibroblasts from elderly donors produced higher amounts of IL6 as well as IL8 than fibroblasts from young donors. These differences were more pronounced for IL6 than for IL8. The inflammatory response of fibroblasts to stimulation differed among donors and did not correspond to the responsiveness of whole blood derived from the same person. In summary lifelong CMV-infection may act as an in vivo trigger for inflammatory changes by increasing the inflammatory response to bacterial products such as LPS. It may thus contribute to age-related inflammatory processes, referred to as 'inflamm-aging'.
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Human rhinovirus (HRV) infections induce epithelial cell production of chemokines that may contribute to the pathogenesis of exacerbations of chronic obstructive pulmonary disease (COPD) and asthma. Cigarette smoking is the predominant risk factor for the development of COPD and also aggravates asthma symptoms. We examined whether cigarette smoke extract (CSE) modulates viral inflammation by altering the profile of HRV-induced epithelial chemokine production. Purified HRV-16, and CSE were used to examine the effects on CXC chemokine ligand (CXCL)8 and CXCL10 production from both primary human bronchial epithelial cells and the BEAS-2B epithelial cell line. Both CSE and HRV-16 induced CXCL8 production and, when used in combination, induced at least an additive production of CXCL8 compared with either stimulus alone. In contrast, CSE did not induce CXCL10 and markedly inhibited HRV-16-induced CXCL10 production. Inhibition of HRV-16-induced CXCL10 by CSE was mediated, at least in part, via transcriptional regulation. The increased CXCL8 production seen with the combination of CSE and HRV-16 was not due to transcriptional regulation but was associated with CXCL8 mRNA stabilisation. Thus, CSE differentially modulates HRV-16-induced chemokine production from human airway epithelial cells in a manner that might be expected to alter inflammatory cell profiles.
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To study the mechanisms by which pneumococcal surface protein A (PspA) up-regulates chemokine CXCL8 in human neutrophils.Human neutrophils were treated by the inhibitors of NF-κB, p38MARK, ERK, JNK respectively, and then CXCL8 concentration in the cell-free supernatants after stimulation with PspA was measured by ELISA. The total cellular proteins and nuclear extracts of neutrophils after stimulation with PspA were prepared to detect p38MARK and NF-κB contents by ELISA. The total cellular proteins were also used for the determination of the phosphorylation levels of p38MAPK and IkB-α by Western blotting.NF-κB or p38MARK inhibitor instead of ERK or JNK inhibitor significantly suppressed the release of CXCL8 induced by PspA. In addition, PspA also increased the activity of p38MAPK and the concentration of NF-κB in the neutrophils. Western blotting indicated that PspA enhanced the phosphorylation levels of p38MAPK and IkB-α.The secretion of CXCL8 in human neutrophils induced by PspA is regulated by p38MAPK and NF-κB pathways.
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The interaction between TiO 2 nanoparticles (NPs) and inflammatory cytokines, including CXCL8, a clinically relevant pro-inflammatory chemokine, was investigated.TiO 2 is present in tissues adjacent to failing implanted Ti (titanium) devices.TiO 2 NPs were shown to bind to CXCL8 in vitro, causing perturbation of quantification of CXCL8 by ELISA, in both simple and complex protein panels, in a dose-dependent manner.Binding between TiO 2 NPs and CXCL8 was demonstrated by protein gel electrophoresis.TiO 2 NPs were also shown to inactivate the chemoattractant property of CXCL8 in a dose-dependent manner, suggesting that the binding between TiO 2 NPs and CXCL8 is likely to be clinically relevant.The results of this study disputed the applicability of detection of CXCL8 by ELISA in systems where TiO 2 NPs were present.Clinically, the disruption of neutrophil chemotaxis due to CXCL8 binding to TiO 2 NPs might result in a hampered inflammatory response.
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Abstract Endotoxin-induced neutrophil recruitment in humans and its potential regulation by CXCL8 clearance. This study examined the establishment of neutrophilic inflammation in humans. We tested the hypotheses that neutrophil recruitment was associated with local CXCL8 production and that neutrophils themselves might contribute to the regulation of the size of the inflammatory response. Humans were challenged i.d. with endotoxin. Biopsies of these sites were examined for cytokine production and leukocyte recruitment by qPCR and IHC. Additional in vitro models of inflammation examined the ability of neutrophils to produce and sequester cytokines relevant to neutrophilic inflammation. i.d. challenge with 15 ng of a TLR4-selective endotoxin caused a local inflammatory response, in which 1% of the total biopsy area stained positive for neutrophils at 6 h, correlating with 100-fold up-regulation in local CXCL8 mRNA generation. Neutrophils themselves were the major source of the early cytokine IL-1β. In vitro, neutrophils mediated CXCL8 but not IL-1β clearance (>90% clearance of ≤2 nM CXCL8 over 24 h). CXCL8 clearance was at least partially receptor-dependent and modified by inflammatory context, preserved in models of viral infection but reduced in models of bacterial infection. In conclusion, in a human inflammatory model, neutrophils are rapidly recruited and may regulate the size and outcome of the inflammatory response through the uptake and release of cytokines and chemokines in patterns dependent on the underlying inflammatory stimulus.
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Purpose: To study the production of angiodrastic chemokines by colonic cancer cell lines. Methods: A pro-angiogenic factor (VEGF), two angiogenic chemokines (CXCL8, CXCL6), and one angiostatic (CXCL4) chemokine were measured by ELISA in the supernatants of the colon cancer cell lines HT-29 and Caco-2. Cells were cultured for 24 h in the presence of serum from cancer patients or healthy individuals. Results were analyzed by one-way ANOVA and the General Linear Model for repeated measures. Results: Colonic epithelial cells are potent producers of angiodrastic chemokines. HT-29 and Caco-2 cells produce all four chemokines under basal conditions and 24 h after incubation with human serum. The secretion response, however, was completely different. HT-29 cells produce more CXCL8 and VEGF irrespective of culture conditions, while Caco-2 cells seem unresponsive with respect to CXCL6 and CXCL4. Moreover, HT-29 cells produce more CXCL8 and VEGF when incubated with cancer serum, contrary to Caco-2 cells which produce more CXCL4 under the same conditions. Conclusions: The two colon cancer cell lines were producers of all chemokines studied, but their responses were not uniform under similar culture conditions. CXCL8 and VEGF are differently regulated compared to CXCL4 and CXCL6 in these two cell lines
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