Polyphosphates are linear polymers and ubiquitous metabolites. Bacterial polyphosphates are long chains of hundreds of phosphate units. Here, we report that mouse survival of peritoneal Escherichia coli sepsis is compromised by long-chain polyphosphates, and improves with bacterial polyphosphatekinase deficiency or neutralization using recombinant exopolyphosphatase. Polyphosphate activities are chain-length dependent, impair pathogen clearance, antagonize phagocyte recruitment, diminish phagocytosis and decrease production of iNOS and cytokines. Macrophages bind and internalize polyphosphates, in which their effects are independent of P2Y1 and RAGE receptors. The M1 polarization driven by E. coli derived LPS is misdirected by polyphosphates in favor of an M2 resembling phenotype. Long-chain polyphosphates modulate the expression of more than 1800 LPS/TLR4-regulated genes in macrophages. This interference includes suppression of hundreds of type I interferonregulated genes due to lower interferon production and responsiveness, blunted STAT1 phosphorylation and reduced MHCII expression. In conclusion, prokaryotic polyphosphates disturb multiple macrophage functions for evading host immunity.
Severe sepsis and septic shock are leading causes of morbidity and mortality worldwide. Infection-associated inflammation promotes the development and progression of adverse outcomes in sepsis. The effects of heterodimeric Interleukin-27 (IL-27; p28/EBI3) have been implicated in the natural course of sepsis, while the molecular mechanisms underlying regulation of gene expression and release of IL-27 in sepsis are poorly understood. In this report we studied the events regulating the p28 subunit of IL-27 in endotoxic shock and polymicrobial sepsis following cecal ligation and puncture. Neutralizing antibodies to IL-27(p28) improved survival rates, confined cytokine release and reduced bacterial burden in C57BL/6 mice during sepsis. Genetic disruption of IL-27 signaling enhanced the respiratory burst of macrophages. Experiments using splenectomized mice or treatment with clodronate liposomes suggested macrophages in the spleen may be a significant source of IL-27(p28) during sepsis. In cultures of TLR4-activated macrophages, the frequency of F4/80+CD11b+IL-27(p28)+ cells was reduced with addition of IL-10. IL-10 antagonized both MyD88-dependent and TRIF-dependent release of IL-27(p28). Genetic deletion of STAT3 in Tie2-Cre/STAT3flox macrophages completely interrupted the inhibition of IL-27(p28) by IL-10 after TLR4-activation. In contrast, IL-10 remained fully active to suppress IL-27(p28) with deletion of SOCS3 in Tie2-Cre/SOCS3flox macrophages. Blockade of the IL-10 receptor by antibody or genetic deficiency of IL-10 resulted in 3-5-fold higher concentrations of IL-27(p28) in endotoxic shock and polymicrobial sepsis. Our studies identify IL-10 as a critical suppressing factor for IL-27(p28) production during infection-associated inflammation. These findings may be helpful for a beneficial manipulation of adverse IL-27(p28) release during sepsis.
Excessive activation of the complement system is detrimental in acute inflammatory disorders. In this study, we analyzed the role of complement‐derived anaphylatoxins in the pathogenesis of experimental acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in C57BL/6J mice. Intratracheal administration of recombinant mouse complement component (C5a) caused alveolar inflammation with abundant recruitment of Ly6‐G+CD11b+ leukocytes to the alveolar spaces and severe alveolar‐capillary barrier dysfunction (C5a‐ALI; EC50[C5a] = 20 ng/g body weight). Equimolar concentrations of C3a or desarginated C5a (C5adesArg) did not induce alveolar inflammation. The severity of C5a‐ALI was aggravated in C5‐deficient mice. Depletion of Ly6‐G+ cells and use of C5aR1‐/‐ bone marrow chimeras suggested an essential role of C5aR1+ hematopoietic cells in C5a‐ALI. Blockade of PI3K/Akt and MEK1/2 kinase pathways completely abrogated lung injury. The mechanistic description is that C5a altered the alveolar cytokine milieu and caused significant release of CC‐chemokines. Mice with genetic deficiency of CC‐chemokine receptor (CCR) type 5, the common receptor of chemokine (C‐C motif) ligand (CCL) 3, CCL4, and CCL5, displayed reduced lung damage. Moreover, treatment with a CCR5 antagonist, maraviroc, was protective against C5a‐ALI. In summary, our results suggest that the detrimental effects of C5a in this model are partly mediated through CCR5 activation downstream of C5aR1, which may be evaluated for potential therapeutic exploitation in ALI/ARDS.—Russkamp, N. F., Ruemmler, R., Roewe, J., Moore, B. B., Ward, P. A., Bosmann, M. Experimental design of complement component 5a‐induced acute lung injury (C5a‐ALI): a role of CC‐chemokine receptor type 5 during immune activation by anaphylatoxin. FASEB J. 29, 3762‐3772 (2015). http://www.fasebj.org
To interfere with cell function, many scientists rely on methods that target DNA or RNA due to the ease with which they can be applied. Proteins are usually the final executors of function but are targeted only indirectly by these methods. Recent advances in targeted degradation of proteins based on proteolysis-targeting chimaeras (PROTACs), ubiquibodies, deGradFP (degrade Green Fluorescent Protein) and other approaches have demonstrated the potential of interfering directly at the protein level for research and therapy. Proteins can be targeted directly and very specifically by antibodies, but using antibodies inside cells has so far been considered to be challenging. However, it is possible to deliver antibodies or other proteins into the cytosol using standard laboratory equipment. Physical methods such as electroporation have been demonstrated to be efficient and validated thoroughly over time. The expression of intracellular antibodies (intrabodies) inside cells is another way to interfere with intracellular targets at the protein level. Methodological strategies to target the inside of cells with antibodies, including delivered antibodies and expressed antibodies, as well as applications in the research areas of neurobiology, viral infections and oncology, are reviewed here. Antibodies have already been used to interfere with a wide range of intracellular targets. Disease-related targets included proteins associated with neurodegenerative diseases such as Parkinson's disease (α-synuclein), Alzheimer's disease (amyloid-β) or Huntington's disease (mutant huntingtin [mHtt]). The applications of intrabodies in the context of viral infections include targeting proteins associated with HIV (e.g. HIV1-TAT, Rev, Vif, gp41, gp120, gp160) and different oncoviruses such as human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV) and Epstein-Barr virus, and they have been used to interfere with various targets related to different processes in cancer, including oncogenic pathways, proliferation, cell cycle, apoptosis, metastasis, angiogenesis or neo-antigens (e.g. p53, human epidermal growth factor receptor-2 [HER2], signal transducer and activator of transcription 3 [STAT3], RAS-related RHO-GTPase B (RHOB), cortactin, vascular endothelial growth factor receptor 2 [VEGFR2], Ras, Bcr-Abl). Interfering at the protein level allows questions to be addressed that may remain unanswered using alternative methods. This review addresses why direct targeting of proteins allows unique insights, what is currently feasible in vitro, and how this relates to potential therapeutic applications.Therapeutic antibodies are valuable drugs, which mostly act outside of cells.Reaching the numerous drug targets that reside inside cells by antibodies is possible in vitro and allows unique insights compared with other methods.Applying antibodies inside cells for therapeutic purposes has been explored in animal models and promises specific therapeutic benefits in neurobiology, virology and oncology.
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