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The calcium-binding proteins S100A8 and S100A9 initiate the early inflammatory program in injured peripheral nerves.

ABSTRACT: To shed light on the early immune response processes in severed peripheral nerves, we performed genome-wide transcriptional profiling and bioinformatics analyses of the proximal (P, regenerating) and distal (D, degenerating) nerve stumps on day 1 in the sciatic nerve axotomy model in rats. Multiple cell death-related pathways were activated in the degenerating D stump, whereas activation of the cytoskeletal motility and gluconeogenesis/glycolysis pathways was most prominent in the P stump of the axotomized nerve. Our bioinformatics analyses also identified the specific immunomodulatory genes of the chemokine, IL, TNF, MHC, immunoglobulin-binding Fc receptor, calcium-binding S100, matrix metalloproteinase, tissue inhibitor of metalloproteinase, and ion channel families affected in both the P and D segments. S100a8 and S100a9 were the top up-regulated genes in both the P and D segments. Stimulation of cultured Schwann cells using the purified S100A8/A9 heterodimer recapitulated activation of the myeloid cell and phagocyte chemotactic genes and pathways, which we initially observed in injured nerves. S100A8/A9 heterodimer injection into the intact nerve stimulated macrophage infiltration. We conclude that, following peripheral nerve injury, an immediate acute immune response occurs both distal and proximal to the lesion site and that the rapid transcriptional activation of the S100a8 and S100a9 genes results in S100A8/A9 hetero- and homodimers, which stimulate the release of chemokines and cytokines by activated Schwann cells and generate the initial chemotactic gradient that guides the transmigration of hematogenous immune cells into the injured nerve.

SUBMITTER: Chernov AV

PROVIDER: S-EPMC4416877 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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The calcium-binding proteins S100A8 and S100A9 initiate the early inflammatory program in injured peripheral nerves.

Chernov Andrei V AV Dolkas Jennifer J Hoang Khang K Angert Mila M Srikrishna Geetha G Vogl Thomas T Baranovskaya Svetlana S Strongin Alex Y AY Shubayev Veronica I VI

The Journal of biological chemistry 20150319 18

To shed light on the early immune response processes in severed peripheral nerves, we performed genome-wide transcriptional profiling and bioinformatics analyses of the proximal (P, regenerating) and distal (D, degenerating) nerve stumps on day 1 in the sciatic nerve axotomy model in rats. Multiple cell death-related pathways were activated in the degenerating D stump, whereas activation of the cytoskeletal motility and gluconeogenesis/glycolysis pathways was most prominent in the P stump of the ...[more]

PMID: 25792748

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Project description:To shed light on the early processes of immune response to peripheral nerve injury, we first used genome-wide transcriptional profiling and bioinformatics (Ingenuity, NextBio) pathway analyses of the proximal (P; regenerating) and distal (D; degenerating) nerve stumps at day 1 in the sciatic nerve axotomy model in rats. We identified a number of specific immunomodulatory genes and pathways that were regulated shortly post-injury in both the P and D segments, including all members of the interleukin (IL), chemokine, tumor necrosis factor (TNF), matrix metalloproteinase (MMP), toll-like receptor (TLR), tissue inhibitor of metalloproteinase (TIMP), ion channel and myosin families. Immunomodulatory calcium-binding S100A8 and S100A9 were the top up-regulated genes in both the D and P segments. In cultured Schwann cells stimulated with the purified S100A8/A9 heterodimer we recorded a high level of similarity of the activated genes and pathways with that of the injured nerve, especially in the activation of the chemokine and cytokine gene networks that support agranulocyte and granulocyte chemotaxis, adhesion, transmigration and rolling signaling pathways. We also confirmed activation of multiple cell death related gene networks supporting TNFR1, natural killer cell receptor and death receptor apoptosis signaling in the D stump, and the gluconeogenesis/glycolysis and cytoskeletal motility signaling in the P stump, corroborated by activation of ERK, PI3K and JNK kinase pathways. As compared to the D segment, multiple additional pathways were more efficiently upregulated in the P stump, including the IL-6 and -17, MMP-9, calcium, activated agranulocyte, leukocyte rolling and glutathione-mediated detoxification signaling pathways. These data suggest that shortly after nerve injury, upregulation of S100A8/A9 is responsible for the expression and release of chemokines and cytokines by Schwann cells, necessary to generate the initial chemotactic gradient and guide the hematogenous immune cells into the injury site. Gene expression profiling of total RNAs extracted from injured and non-injured rat sciatic nerves, and primary rat Schwann cells stimulated with S100A8/A9 proteins

Project description:BACKGROUND:Atherosclerotic occlusions decrease blood flow to the lower limbs, causing ischemia and tissue loss in patients with peripheral artery disease (PAD). No effective medical therapies are currently available to induce angiogenesis and promote perfusion recovery in patients with severe PAD. Clinical trials aimed at inducing vascular endothelial growth factor (VEGF)-A levels, a potent proangiogenic growth factor to induce angiogenesis, and perfusion recovery were not successful. Alternate splicing in the exon-8 of VEGF-A results in the formation of VEGFxxxa (VEGF165a) and VEGFxxxb (VEGF165b) isoforms with existing literature focusing on VEGF165b's role in inhibiting vascular endothelial growth factor receptor 2-dependent angiogenesis. However, we have recently shown that VEGF165b blocks VEGF-A-induced endothelial vascular endothelial growth factor receptor 1 (VEGFR1) activation in ischemic muscle to impair perfusion recovery. Because macrophage-secreted VEGF165b has been shown to decrease angiogenesis in peripheral artery disease, and macrophages were well known to play important roles in regulating ischemic muscle vascular remodeling, we examined the role of VEGF165b in regulating macrophage function in PAD. METHODS:Femoral artery ligation and resection were used as an in vivo preclinical PAD model, and hypoxia serum starvation was used as an in vitro model for PAD. Experiments including laser-Doppler perfusion imaging, adoptive cell transfer to ischemic muscle, immunoblot analysis, ELISAs, immunostainings, flow cytometry, quantitative polymerase chain reaction analysis, and RNA sequencing were performed to determine a role of VEGF165b in regulating macrophage phenotype and function in PAD. RESULTS:First, we found increased VEGF165b expression with increased M1-like macrophages in PAD versus non-PAD (controls) muscle biopsies. Next, using in vitro hypoxia serum starvation, in vivo pre clinical PAD models, and adoptive transfer of VEGF165b-expressing bone marrow-derived macrophages or VEGFR1+/- bone marrow-derived macrophages (M1-like phenotype), we demonstrate that VEGF165b inhibits VEGFR1 activation to induce an M1-like phenotype that impairs ischemic muscle neovascularization. Subsequently, we found S100A8/S100A9 as VEGFR1 downstream regulators of macrophage polarization by RNA-Seq analysis of hypoxia serum starvation-VEGFR1+/+ versus hypoxia serum starvation-VEGFR1+/- bone marrow-derived macrophages. CONCLUSIONS:In our current study, we demonstrate that increased VEGF165b expression in macrophages induces an antiangiogenic M1-like phenotype that directly impairs angiogenesis. VEGFR1 inhibition by VEGF165b results in S100A8/S100A9-mediated calcium influx to induce an M1-like phenotype that impairs ischemic muscle revascularization and perfusion recovery.

Project description:INTRODUCTION: The objective was to evaluate the changes in S100A8 S100A9, and their complex (S100A8/S100A9) in cartilage during the onset of osteoarthritis (OA) as opposed to inflammatory arthritis. METHODS: S100A8 and S100A9 protein localization were determined in antigen-induced inflammatory arthritis in mice, mouse femoral head cartilage explants stimulated with interleukin-1 (IL-1), and in surgically-induced OA in mice. Microarray expression profiling of all S100 proteins in cartilage was evaluated at different times after initiation of degradation in femoral head explant cultures stimulated with IL-1 and surgically-induced OA. The effect of S100A8, S100A9 or the complex on the expression of aggrecan (Acan), collagen II (Col2a1), disintegrin and metalloproteases with thrombospondin motifs (Adamts1, Adamts 4 &Adamts 5), matrix metalloproteases (Mmp1, Mmp3, Mmp13 &Mmp14) and tissue inhibitors of metalloproteinases (Timp1, Timp2 &Timp3), by primary adult ovine articular chondrocytes was determined using real time quantitative reverse transcription polymerase chain reaction (qRT-PCR). RESULTS: Stimulation with IL-1 increased chondrocyte S100a8 and S100a9 mRNA and protein levels. There was increased chondrocyte mRNA expression of S100a8 and S100a9 in early but not late mouse OA. However, loss of the S100A8 staining in chondrocytes occurred as mouse OA progressed, in contrast to the positive reactivity for both S100A8 and S100A9 in chondrocytes in inflammatory arthritis in mice. Homodimeric S100A8 and S100A9, but not the heterodimeric complex, significantly upregulated chondrocyte Adamts1, Adamts4 and Adamts 5, Mmp1, Mmp3 and Mmp13 gene expression, while collagen II and aggrecan mRNAs were significantly decreased. CONCLUSIONS: Chondrocyte derived S100A8 and S100A9 may have a sustained role in cartilage degradation in inflammatory arthritis. In contrast, while these proteins may have a role in initiating early cartilage degradation in OA by upregulating MMPs and aggrecanases, their reduced expression in late stages of OA suggests they do not have an ongoing role in cartilage degradation in this non-inflammatory arthropathy.

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The calcium-binding proteins S100A8 and S100A9 initiate the early inflammatory program in injured peripheral nerves.

Publications

The calcium-binding proteins S100A8 and S100A9 initiate the early inflammatory program in injured peripheral nerves.

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