Transcriptomic Profiling Reveals That HMGB1 Induces Macrophage Polarization Different from Classical M1

Macrophages are key inflammatory immune cells that display dynamic phenotypes and functions in response to their local microenvironment. In different conditions, macrophage polarization can be induced by high-mobility group box 1 (HMGB1), a nuclear DNA-binding protein that activates innate immunity via the Toll-like receptor (TLR) 4, the receptor for advanced glycation end products (RAGE), and C-X-C chemokine receptor (CXCR) 4. This study investigated the phenotypes of murine bone-marrow-derived macrophages (BMDMs) stimulated with different HMGB1 redox isoforms using bulk RNA sequencing (RNA-Seq). Disulfide HMGB1 (dsHMGB1)-stimulated BMDMs showed a similar but distinct transcriptomic profile to LPS/IFNγ- and LPS-stimulated BMDMs. Fully reduced HMGB1 (frHMGB1) did not induce any significant transcriptomic change. Interestingly, compared to LPS/IFNγ- and LPS-, dsHMGB1-stimulated BMDMs showed lipid metabolism and foam cell differentiation gene set enrichment, and oil red O staining revealed that both dsHMGB1 and frHMGB1 alleviated oxidized low-density lipoprotein (oxLDL)-induced foam cells formation. Overall, this work, for the first time, used transcriptomic analysis by RNA-Seq to investigate the impact of HMGB1 stimulation on BMDM polarization. Our results demonstrated that dsHMGB1 and frHMGB1 induced distinct BMDM polarization phenotypes compared to LPS/IFNγ- and LPS- induced phenotypes.publishedVersio

Bulk collagen incorporation rates into knitted stiff fibre polymer in tissue-engineered scaffolds : the rate-limiting step

Fabrication of tissue-engineered constructs in vitro relies on sufficient synthesis of extracellular matrix (ECM) by cells to form a material suitable for normal function in vivo. Collagen synthesis by human dermal fibroblasts grown in vitro on two polymers, polyethylene terephthalate (PET) and polyglycolic acid (PGA), was measured by high-performance liquid chromatography (HPLC). Cells were either cultured in a dynamic environment, where meshes were loaded onto a pulsing tube in a bioreactor, or in a static environment without pulsing. Collagen synthesis by cells cultured on a static mesh increased by six-fold compared to monolayer culture, and increased by up to a further 5.4-fold in a pulsed bioreactor. However, little of the collagen synthesized was deposited onto the meshes, almost all being lost to the medium. The amount of collagen deposited onto meshes was highest when cells were cultured dynamically on PET meshes (17.6 mu g), but deposition still represented only 1.4% of the total synthesized. Although total collagen synthesis was increased by the use of 3D culture and the introduction of pulsing, the results suggest that the limiting factor for fabrication of a tissue-engineered construct within practical timescales is not the amount of collagen synthesized but the quantity retained (i.e. deposited) within the construct during culture. This may be enhanced by systems which promote or assemble true 3D multi-layers of cells. Copyright (C) 2008 John Wiley & Sons, Ltd

Juvenile idiopathic arthritis patients have a distinct cartilage and bone biomarker profile that differs from healthy and knee-injured children

OBJECTIVES: Joint destruction is a hallmark of juvenile idiopathic arthritis (JIA). Clinical evaluation and radiographic imaging are current methods to identify destruction. Biomarkers could aid an earlier and more sensitive diagnosis. Our aim was to investigate levels of bone and cartilage degradation biomarkers in JIA patients, compared to healthy children or juveniles with knee injuries. METHODS: Triple-paired synovial fluid, plasma and urine samples from 29 JIA patients were compared to 61 plasma samples from healthy children and synovial fluid from 41 knee-injured juveniles. Cartilage biomarkers ARGS neoepitope of aggrecan (ARGS), cartilage oligomeric matrix protein (COMP), type II collagen epitope (C2C), bone biomarkers N-terminal type I collagen cross-linked telopeptide (NTX-I) and tartrate-resistant acid phosphatase 5b (TRAP5b) were analysed by immunoassays. RESULTS: Plasma levels of ARGS, C2C, COMP and TRAP5b were increased in JIA compared to healthy children. Compared to knee-injured juveniles, synovial fluid C2C and TRAP5b were increased in JIA, while ARGS and COMP were decreased. For JIA patients, local (synovial fluid) and systemic (plasma/urine) levels of bone biomarkers correlated positively; age correlated negatively to plasma levels of C2C and TRAP5b; no correlation was found between biomarkers and gender, affected joint count, disease duration or medication. CONCLUSIONS: Elevated levels of destruction biomarkers in JIA compared to healthy children indicate a potential to serve as clinical tools for destructive joint disease. High levels of TRAP5b, NTX-I and collagen II in JIA in contrast to more pronounced aggrecan and COMP degradation in juvenile knee injuries, suggests that JIA patients have a unique biomarker pattern, different from healthy and knee-injured children

Supplementary Figure -Supplemental material for Fragmented hyaluronan has no alarmin function assessed in arthritis synovial fibroblast and chondrocyte cultures

<p>Supplemental material, Supplementary Figure for Fragmented hyaluronan has no alarmin function assessed in arthritis synovial fibroblast and chondrocyte cultures by Mia Olsson, Lisa Bremer, Cecilia Aulin and Helena Erlandsson Harris in Innate Immunity</p

In vitro degradation and in vivo biocompatibility study of a new linear poly(urethane urea)

Segmented poly(urethane urea)s (PUUs) with hard segments derived only from methyl 2,6-diisocyantohexanoate (LDI) without the use of a chain extender have previously been described. These materials, which contain hard segments with multiple urea linkages, show exceptionally high strain capability (1600-4700%). In the study reported here, the rate and effect of hydrolysis of these materials were determined for gamma-sterilized and nonsterilized samples. Materials investigated contained PCL, PTMC, P(TMC-co-CL), P(CL-co-DLLA), or P(TMC-co-DLLA) as soft segments and, as well as their mechanical properties, changes in mass, inherent viscosity (IN.), and thermal properties were studied over 20 weeks. Results showed that the degradation rate was dependant on the soft segment structure, with a higher rate of degradation for the polyester-dominating PUUs exhibiting a substantial loss in IN. A tendency of reduction of tensile strength and strain hardening was seen for all samples. Also, loss in elongation at break was detected, for PUU-P(CL-DLLA) it went from 1600% to 830% in 10 weeks. Gamma radiation caused an initial loss in I.V. and induced more rapid hydrolysis compared with nonsterilized samples, except for PUU-PTMC. A cytotoxicity test using human fibroblasts demonstrated that the material supports cell viability. In addition, an in vivo biocompatibility study showed a typical foreign body reaction after I and 6 weeks

Nitrosative modifications of the Ca2+ release complex and actin underlie arthritis-induced muscle weakness.

Skeletal muscle weakness is a prominent clinical feature in patients with rheumatoid arthritis (RA), but the underlying mechanism(s) is unknown. Here we investigate the mechanisms behind arthritis-induced skeletal muscle weakness with special focus on the role of nitrosative stress on intracellular Ca(2+) handling and specific force production