The lack of thus prospects to increased differentiation and activation of myeloid cells in granulocytes, monocytes and dendritic cells. Aggravated arthritis in S100a8-/- mice Elevated concentrations of calprotectin are found in the plasma and synovial fluids of rheumatoid arthritis patients, and S100A9 is known to exacerbate chronic inflammation in models of arthritis [6, 24, 49, 50]. of TP-10 WT NCAM1 and mice, based on circulation cytometry (n = 10). (D) Leukocyte migration to the peritoneum in response to thioglycolate in WT and mice. Leukocytes were recovered 4 h after intra-peritoneal injection of thioglycolate or PBS (n = 3 or 8).(TIF) pone.0221528.s002.tif (21M) GUID:?AF363661-A11F-4AAE-ABEE-9A3698443A36 S3 Fig: Oxygen consumption in murine neutrophils is almost completely dependent on NADPH oxidase. Oxygen consumption rate in response to PMA activation of neutrophils purified by unfavorable selection from bone marrows of WT and mice was quantified using an extracellular flux analyzer. Neutrophils were incubated in the presence or absence of 5 M of the NADPH oxidase inhibitor DPI. Values are mean sem for 4 wells from one experiment representative of 3.(TIF) pone.0221528.s003.tif (7.0M) GUID:?A54D97BA-28E0-447B-9F09-29E3576444DF S4 Fig: Analysis of bone marrow cells in mice. (A) Gating strategy used in circulation cytometry to detect GMP (Lin-Sca1-cKit+CD16/32high-medCD34+), CMP (Lin-Sca1-cKit+CD16/32med-lowCD34+ cells) and MEP (Lin-Sca1-cKit+CD16/32lowCD34-) cells. (B) Circulation cytometry gating strategy used to detect MDP (R1, CD117+CD115+CD135+Ly6C-CD11b-) and cMop (R2, CD117+CD115+CD135-Ly6C+CD11b-) cells. C) Percentages of MDP and cMop cells in WT and bone marrows (n = 6).(TIF) pone.0221528.s004.tif (24M) GUID:?2179BA4B-AB09-499C-A0B6-CFEFC1EDA20A S1 Table: List of antibodies used in this study. (DOCX) pone.0221528.s005.docx (13K) GUID:?D552BD86-7DE7-4760-BAC3-AC6F75A2C3F8 S2 Table: Demographic and clinical data of the research project participants. (DOCX) pone.0221528.s006.docx (13K) GUID:?066CA2B6-ABCF-4C39-A1F3-AC93F28FEDAF Data Availability StatementAll files are available from your OSF database (DOI 10.17605/OSF.IO/Y4UWZ). Abstract Expressed strongly by myeloid cells, damage-associated molecular pattern (DAMP) proteins S100A8 and S100A9 are TP-10 found in the serum of patients with infectious and autoimmune diseases. Compared to S100A9, the role of S100A8 is usually controversial. We investigated its biological activity in collagen-induced arthritis using the first known viable and fertile mice experienced increased numbers of neutrophils, monocytes and dendritic cells in the blood and bone marrow, and these all expressed myeloid markers such as CD11b, Ly6G and CD86 more strongly. Granulocyte-macrophage common precursors were increased in bone marrow and yielded greater numbers of macrophages and dendritic cells in culture. The animals also developed more severe arthritic disease leading to aggravated osteoclast activity and bone destruction. These findings were correlated with increased inflammatory cell infiltration and cytokine secretion in the paws. This study suggests that S100A8 is an anti-inflammatory DAMP that regulates myeloid cell differentiation, thereby mitigating the development of experimental arthritis. Introduction TP-10 Analogous to pathogen-associated molecular patterns, damage-associated molecular patterns or DAMPs, also known as alarmins, are endogenous molecules released passively by cells undergoing non-programmed cell death as well as actively through normal secretion pathways [1]. They are believed to play important functions in the progression of inflammatory diseases such as rheumatoid arthritis [2], systemic lupus erythematosus [3] and inflammatory bowel disease [4]. The DAMPs S100A8 and S100A9 belong to a subset of S100 proteins called myeloid related proteins (MRPs) because they are predominantly expressed in neutrophils and monocytes [5]. These include S100A8 and S100A9, which are expressed constitutively in myeloid cells and are inducible in synoviocytes[6], keratinocytes[7], epithelial cells [8], endothelial cells [9] and other cell types. S100A8 and S100A9 form non-covalently bonded homodimers and a heterodimer called S100A8/A9 or calprotectin [10]. The three dimers are not usually co-expressed [9] and are secreted independently during inflammatory responses through alternate secretion pathways impartial of Golgi and secretion vesicles [11, 12]. It is therefore presumed that they have different activities. While S100A9 has been analyzed extensively, the activities of S100A8 remain controversial. S100A9 stimulates pro-inflammatory cytokine secretion [13, 14], neutrophil phagocytosis.