Neutrophilic cell-free exudate induces antinociception mediate by the protein S100A9

Anti-Inflammatory Effects of BoNT/A Against Complete Freund's Adjuvant-Induced Arthritis Pain in Rats: Transcriptome Analysis

Arthritis is the most common cause to lead to chronic pain. Botulinum toxin type A (BoNT/A) has been widely used to treat chronic pain. In our previous study, we confirmed the anti-inflammatory and antinociceptive effects of BoNT/A in the Complete Freund’s Adjuvant (CFA)-induced arthritis model, but the underlying anti-inflammatory mechanism was not fully elucidated. The purpose of this study was to investigate the anti-inflammatory effects and mechanisms of BoNT/A on arthritis using transcriptomic analysis. The BoNT/A was injected into the rat ankle joint on day 21 after CFA injection. The von Frey and hot plate tests were applied to assess the pain-related behaviors at different time points. Five days after BoNT/A treatment, gene expression profiling in dorsal root ganglion (DRG) was performed using RNA sequencing (RNA-seq). The differentially expressed genes (DEGs) were analyzed by various tools. The mechanical allodynia and thermal hyperalgesia were significantly reversed after BoNT/A injection. RNA-seq revealed 97 DEGs between the CFA group and Sham group; these DEGs were enriched inflammatory response, IL-17 signaling pathway, etc. There are 71 DEGs between the CFA+BoNT/A group and the CFA group; these DEGs related to response to peptide, PI3K-Akt signaling pathway, ECM–receptor interactions, etc. Three key genes were significantly decreased after CFA-induced arthritis pain, while BoNT/A increased the expression of these genes. The identification of S100A9, S100A8, and MMP8 genes can provide new therapeutic targets for arthritis pain and affect the signaling pathway to play an anti-inflammatory role after the treatment of BoNT/A.

[Effect of cyanopyrrolidine derivatives on the activity of prolylendopeptidase, acute exudative inflammation and visceral pain in mice]

Cyanopyrrolidine derivatives benzyloxycarbonyl-methionyl-cyanopyrrolidine (ZMetPrdN), benzyloxycarbonylphenylalanyl- cyanopyrrolidine (ZPhePrdN), tert-butyl-hydroxycarbonyl-glycyl-cyanopyrrolidine (BocGlyPrdN), tert-butyl-hydroxycarbonyl-methionyl-cyanopyrrolidine (BocMetPrdN) are inhibitors of prolylendopeptidase (PREP; EC 3.4.21.26) with an IC50 of 2 nM to 12 nM. ZMetPrdN, ZPhePrdN and BocMetPrdN additionally inhibited dipeptidyl peptidase IV (DPP-4; EC 3.4.14.5) with an IC50 of 1100 nM to 3200 nM. All the compounds have antinociceptive properties in the acetic acid writhing test in mice. But only cyanopyrrolidine derivatives with aromatic substituents decrease exudative inflammation. The cyanopyrrolidine derivatives also increase PREP activity and compensatorily reduce DPP-4 activity in the serum of mice three hours after the induction of inflammation. Thus, cyanopyrrolidine derivatives exhibit antinociceptive and antiexudative properties in part via their effect on PREP.

Inhibition of macrophage functions by the C-terminus of murine S100A9 is dependent on B-1 cells

The protein S100A9 plays a key role in the control of inflammatory response. The C-terminus of the murine S100A9 protein (mS100A9p) downregulates the spreading and phagocytic activity of adherent peritoneal cells. Murine peritoneal cells are constituted by macrophages and B-1 cells, and the latter exert an inhibitory effect on macrophage functions by secreting interleukin- (IL-) 10. Here, we investigated the influence of B-1 cells on the inhibitory effect evoked by mS100A9p on macrophages. mS100A9p did not alter spreading and phagocytosis either by peritoneal macrophages obtained from mice deprived of B-1 cells or by bone marrow-derived macrophages (BMDMϕ). Nevertheless, when BMDMϕ were cocultivated by direct or indirect contact with B-1 cells treated with mS100A9p, the phagocytosis by BMDMϕ was decreased, showing that the effect of mS100A9p on macrophages was modulated by B-1 cells and/or their secretory compounds. Furthermore, the inhibitory action of mS100A9p on phagocytosis by adherent peritoneal cells was abolished in cells obtained from IL-10 knockout mice. Taken together, the results show that mS100A9p has no direct inhibitory effect on macrophages; however, mS100A9p modulates B-1 cells, which in turn downregulates macrophages, at least in part, via IL-10. These data contribute to the characterization of S100A9 functions involving B-1 cells in the regulation of the inflammatory process.

Delayed increase of S100A9 messenger RNA predicts hospital-acquired infection after septic shock

OBJECTIVE

Septic shock remains a serious disease with high mortality and increased risk of hospital-acquired infection. The prediction of outcome is of the utmost importance for selecting patients for therapeutic strategies aiming to modify the immune response. The aim of this study was to assess the capability of S100A9 messenger RNA in whole blood from patients with septic shock to predict survival and the occurrence of hospital-acquired infection.

DESIGN

Cohort study.

SETTING

Two intensive care units in a university hospital.

SUBJECTS

The study included patients with septic shock (n = 166) and healthy volunteers (n = 44).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

For the patients with septic shock patients, overall mortality was 38% and the mean Simplified Acute Physiologic Scale II on shock onset was 52. Using quantitative reverse transcriptase-polymerase chain reactions, we found that median S100A9 messenger RNA was significantly lower in healthy volunteers than in patients with septic shock (p < .0001) between days 1 and 3 after onset of the septic shock and not significantly different between nonsurvivor and survivor patients (p = .1278). However, median S100A9 messenger RNA measured on days 7-10 was significantly higher in patients who were about to contract hospital-acquired infections compared with those who were not (p = .009). In the multivariate analysis, the S100A9 marker increased the probability of contracting hospital-acquired infections with an odds ratio of 1.12 per unit (p = .0054).

CONCLUSIONS

S100A9 messenger RNA is increased in septic shock and its delayed overexpression is associated with the occurrence of secondary hospital-acquired infection. This biomarker may be of major interest in identifying patients with increased risk of hospital-acquired infection who could benefit from targeted therapy aimed at restoring their immune functions.

Inflammation-associated S100 proteins: new mechanisms that regulate function

This review focuses on new aspects of extracellular roles of the calgranulins. S100A8, S100A9 and S100A12 are constitutively expressed in neutrophils and induced in several cell types. The S100A8 and S100A9 genes are regulated by pro- and anti-inflammatory mediators and their functions may depend on cell type, mediators within a particular inflammatory milieu, receptors involved in their recognition and their post-translational modification. The S100A8 gene induction in macrophages is dependent on IL-10 and potentiated by immunosuppressive agents. S100A8 and S100A9 are oxidized by peroxide, hypochlorite and nitric oxide (NO). HOCl generates intra-chain sulfinamide bonds; stronger oxidation promotes cross-linked forms that are seen in human atheroma. S100A8 is >200-fold more sensitive to oxidative cross-linking than low-density lipoprotein and may reduce oxidative damage. S100A8 and S100A9 can be S-nitrosylated. S100A8-SNO suppresses mast cell activation and inflammation in the microcirculation and may act as an NO transporter to regulate vessel tone in inflammatory lesions. S100A12 activates mast cells and is a monocyte and mast cell chemoattractant; a G-protein-coupled mechanism may be involved. Structure-function studies are discussed in relation to conservation and divergence of functions in S100A8. S100A12 induces cytokines in mast cells, but not monocytes/macrophages. It forms complexes with Zn(2+) and, by chelating Zn(2+), S100A12 significantly inhibits MMPs. Zn(2+) in S100A12 complexes co-localize with MMP-9 in foam cells in atheroma. In summary, S100A12 has pro-inflammatory properties that are likely to be stable in an oxidative environment, because it lacks Cys and Met residues. Conversely, S100A8 and S100A9 oxidation and S-nitrosylation may have important protective mechanisms in inflammation.

Macrophage suppression following phagocytosis of apoptotic neutrophils is mediated by the S100A9 calcium-binding protein

The clearance of apoptotic cells by phagocytes is a fundamental process during tissue remodeling and resolution of inflammation. In turn, the phagocytosis of apoptotic cells generates signals that suppress pro-inflammatory activation of macrophages. These events occur during the resolution phase of inflammation and therefore the malfunctioning of this process may lead to inflammation-related tissue damage. Here, we demonstrate that the calcium-binding protein S100A9, normally abundant in the cytoplasm of neutrophils and also released by apoptotic neutrophils, is involved in the suppression of macrophages after the uptake of apoptotic neutrophils. Both, spontaneous and induced production of inflammatory species (nitric oxide, hydrogen peroxide and TNF-alpha) as well as the phagocytic activity were inhibited when macrophages were in presence of apoptotic neutrophils, conditioned medium from neutrophil cultures or a peptide corresponding to the C-terminal region of S100A9 protein. On the other hand, macrophages kept in the conditioned medium of neutrophils that was previously depleted of S100A9 were shown to resume the activated status. Finally, we demonstrate that the calcium-binding property of S100A9 might play a role in the suppression process, since the stimulation of intracellular calcium release with ionomycin significantly reversed the effects of the uptake of apoptotic neutrophils in macrophages. In conclusion, we propose that S100A9 is a novel component of the regulatory mechanisms of inflammation, acting side-by-side with other suppressor factors generated upon ingestion of apoptotic cells.

Antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain

The synthetic peptide identical to the C-terminus of murine S100A9 protein (mS100A9p) has antinociceptive effect on different acute inflammatory pain models. In this study, the effect of mS100A9p was investigated on neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Hyperalgesia, allodynia, and spontaneous pain were assessed to evaluate nociception. These three signs were detected as early as 2 days after sciatic nerve constriction and lasted for over 14 days after CCI. Rats were treated with different doses of mS100A9p by intraplantar, oral, or intrathecal routes on day 14 after CCI, and nociception was evaluated 1h later. These three routes of administration blocked hyperalgesia, allodynia and spontaneous pain. The duration of the effect of mS100A9p depends on the route used and phenomenon analyzed. Moreover, intraplantar injection of mS100A9p in the contralateral paw inhibited the hyperalgesia on day 14 days after CCI. The results obtained herein demonstrate the antinociceptive effect of the C-terminus of murine S100A9 protein on experimental neuropathic pain, suggesting a potential therapeutic use for it in persistent pain syndromes, assuming that tolerance does not develop to mS100A9p.