Aim

This study aimed to evaluate the impact of intraoperative direct sonication on the yield of traditional culture and the time to positivity (TTP) of cultures obtained for periprosthetic joint infection (PJI), thereby assessing its potential to improve diagnostic efficiency and reduce contamination risk.

Introduction

Promoting bone mass homeostasis keeps skeleton away from osteoporosis. a-Ketoglutarate (a-KG) is an indispensable intermediate of tricarboxylic acid cycle (TCA) process for cellular energy production. a-KG mitigates cellular senescence, tissue degeneration, and oxidative stress. We investigated whether a-KG affected osteoblast activity or osteoporosis development.

Introduction

Osteoporosis accounts for a major risk factor of fracture-associated disability or premature death in the elderly. Enhancement of bone anabolism for slowing osteoporosis is highly demanding. Exerkine fibronectin type III domain containing 5 (FNDC5) regulates energy metabolism, inflammation, and aging. This study was aimed to investigate whether Fndc5 signaling in osteoblasts changed estrogen deficiency-mediated bone loss or microarchitecture deterioration.

Introduction

Cartilage damage is a critical aspect of osteoarthritis progression, but effective imaging strategies remain limited. Consequently, multimodal imaging approaches are receiving increased attention. Gold nanomaterials, renowned for their therapeutic and imaging capabilities, hold promise in drug development. However, their potential for cartilage imaging is rarely discussed. Here, we developed a versatile nanomaterial, AuNC@BSA-Gd-I, for cartilage detection. By leveraging electrostatic interactions with sulfated glycosaminoglycans (sGAG), the AuNC@BSA-Gd-I can effectively penetrate damaged cartilage while accumulating minimally in healthy cartilage. This probe can be visualized or detected using CT, MRI, IVIS, and a gamma counter, providing a comprehensive approach to cartilage imaging. Additionally, we compared the imaging abilities, cartilage visualization capacities, and versatility of currently disclosed multimodal gold nanomaterials with those of AuNC@BSA-Gd-I.

Aims

The optimum type of antibiotics and their administration route for treating Gram-negative (GN) periprosthetic joint infection (PJI) remain controversial. This study aimed to determine the GN bacterial species and antibacterial resistance rates related to clinical GN-PJI, and to determine the efficacy and safety of intra-articular (IA) antibiotic injection after one-stage revision in a GN pathogen-induced PJI rat model of total knee arthroplasty.

Aims

This study aimed to assess the risk of acute kidney injury (AKI) associated with combined intravenous (IV) and topical antibiotic therapy in patients undergoing treatment for periprosthetic joint infections (PJIs) following total knee arthroplasty (TKA), utilizing the Kidney Disease: Improving Global Outcomes (KDIGO) criteria for classification.

Obesity is correlated with the development of osteoporotic diseases. Gut microbiota-derived metabolite trimethylamine-n-oxide (TMAO) accelerates obesity-mediated tissue deterioration. This study was aimed to investigate what role TMAO may play in osteoporosis development during obesity.

Mice were fed with high-fat diet (HFD; 60 kcal% fat) or chow diet (CD; 10 kcal% fat) or 0.2% TMAO in drinking water for 6 months. Body adiposis and bone microstructure were investigated using μCT imaging. Gut microbiome and serum metabolome were characterized using 16S rRNA sequencing and liquid chromatography-tandem mass spectrometry. Osteogenic differentiation of bone-marrow mesenchymal cells was quantified using RT-PCR and von Kossa staining. Cellular senescence was evaluated by key senescence markers p16, p21, p53, and senescence association β-galactosidase staining.

HFD-fed mice developed hyperglycemia, body adiposis and osteoporosis signs, including low bone mineral density, sparse trabecular microarchitecture, and decreased biomechanical strength. HFD consumption induced gut microbiota dysbiosis, which revealed a high Firmicutes/Bacteroidetes ratio and decreased α-diversity and abundances of beneficial microorganisms Akkermansiaceae, Lactobacillaceae, and Bifidobacteriaceae. Serum metabolome uncovered increased serum L-carnitine and TMAO levels in HFD-fed mice. Of note, transplantation of fecal microbiota from CD-fed mice compromised HFD consumption-induced TMAO overproduction and attenuated loss in bone mass, trabecular microstructure, and bone formation rate. TMAO treatment inhibited trabecular and cortical bone mass and biomechanical characteristics; and repressed osteogenic differentiation capacity of bone-marrow mesenchymal cells. Mechanistically, TMAO accelerated mitochondrial dysfunction and senescence program, interrupted mineralized matrix production in osteoblasts.

Gut microbial metabolite TMAO induced osteoblast dysfunction, accelerating the development of obesity-induced skeletal deterioration. This study, for the first time, conveys a productive insight into the catabolic role of gut microflora metabolite TMAO in regulating osteoblast activity and bone tissue integrity during obesity.

Osteoporosis (OP) and osteoarthritis (OA) are leading causes of musculoskeletal dysfunction in elderly, with chondrocyte senescence, inflammation, oxidative stress, subcellular organelle dysfunction, and genomic instability as prominent features. Age-related intestinal disorders and gut dysbiosis contribute to host tissue inflammation and oxidative stress by affecting host immune responses and cell metabolism. Not surprisingly, the development of OP and OA correlate with dysregulations of the gut microflora in rodents and humans. Intestinal microorganisms produce metabolites, including short-chain fatty acids, bile acids, trimethylamine N-oxide, and liposaccharides, affecting mitochondrial function, metabolism, biogenesis, autophagy, and redox reactions in chondrocytes to regulate joint homeostasis. Modulating the abundance of specific gut bacteria, like Lactobacillus and Bifidobacterium, by probiotics or fecal microbiota transplantation appears to suppress age-induced chronic inflammation and oxidative damage in musculoskeletal tissue and holds potential to slow down OP development. The talk will highlight treatment options with probiotics or metabolites for modulating the progression of OA and OP.

Aims

Mechanical stimulation is a key factor in the development and healing of tendon-bone insertion. Treadmill training is an important rehabilitation treatment. This study aims to investigate the benefits of treadmill training initiated on postoperative day 7 for tendon-bone insertion healing.

Senescent chondrocyte and subchondral osteoclast overburden aggravate inflammatory cytokine and pro-catabolic proteinase overproduction, accelerating extracellular matrix degradation and pain during osteoarthritis (OA). Fibronectin type III domain containing 5 (FNDC5) is found to promote tissue homeostasis and alleviate inflammation. This study aimed to characterize what role Fndc5 may play in chondrocyte aging and OA development.

Serum and macroscopically healthy and osteoarthritic cartilage were biopsied from patients with knee OA who received total knee replacement. Murine chondrocytes were transfected with Fndc5 RNAi or cDNA. Mice overexpressing Fndc5 (Fndc5Tg) were operated to have destabilized medial meniscus mediated (DMM) joint injury as an experimental OA model. Cellular senescence was characterized using RT-PCR analysis of p16INK4A, p21CIP1, and p53 expression together with ß-galactosidase activity staining. Articular cartilage damage and synovitis were graded using OARSI scores. Osteophyte formation and mechanical allodynia were quantified using microCT imaging and von Frey filament, respectively. Osteoclast formation was examined using tartrate-resistant acid phosphatase staining.

Senescent chondrocyte and subchondral osteoclast overburden together with decreased serum FNDC5 levels were present in human osteoarthritic cartilage. Fndc5 knockdown upregulated senescence program together with increased IL-6, MMP9 and Adamts5 expression, whereas Alcian blue-stained glycosaminoglycan production were inhibited. Forced Fndc5 expression repressed senescence, apoptosis and IL-6 expression, reversing proliferation and extracellular matrix production in inflamed chondrocytes. Fndc5Tg mice showed few OA signs, including articular cartilage erosion, synovitis, osteophyte formation, subchondral plate sclerosis and mechanical allodynia together with decreased IL-6 production and few senescent chondrocytes and subchondral osteoclast formation during DMM-induced joint injury. Mechanistically, Fndc5 reversed histone H3K27me3-mediated IL-6 transcription repression to reduce reactive oxygen species production.

Fndc5 loss correlated with OA development. It was indispensable in chondrocyte growth and anabolism. This study sheds light onto the anti-ageing and anti-inflammatory actions of Fndc5 to chondrocytes; and highlights the chondroprotective function of Fndc5 to compromise OA.

Introduction and Objective

Senescent bone cell overburden accelerates osteoporosis. Epigenetic alteration, including microRNA signalling and DND methylation, is one of prominent features of cellular senescence. This study aimed to investigate what role microRNA-29a signalling may play in the development of senile osteoporosis.

Glucocorticoid excess is shown to deteriorate bone tissue integrity, increasing the risk of osteoporosis. Marrow adipogenesis at cost of osteogenesis is a prominent feature of this osteoporosis condition. Epigenetic pathway histone deacetylase (HDAC)-mediated histone acetylation regulates osteogenic activity and bone mass. This study is aimed to figure out what role of acetylated histone reader bromodomain-containing protein 4 (BRD4) did play in glucocorticoid-induced osteoporosis.

Bone-marrow mesenchymal stem cells were incubated in osteogenic medium with or without 1 μM dexamethasone. Mineralized matrix and adipocyte formation were probed using von Kossa and Nile Red O staining, respectively. Osteogenic and adipogenic marker expression were quantified using RT-PCR. The binding of acetylated histone to promoter of transcription factors were detected using chromatin immunoprecipitation-PCR. Bone mineral density and microstructure in osteoporotic bone were quantified with microCT system.

Glucocorticoid repressed osteogenic transcription factor Runx2 expression and mineralized matrix formation along with a low level of acetylated lysine 9 at histone 3 (H3K9ac), whereas BRD4 signaling and adipocytic formation were increased in cell cultures. BRD4 knockdown reversed the H3K9ac enrichment in Runx2 promoter and osteogenesis, but downregulated adipogenic differentiation. Silencing BRD4 attenuated H3K9ac occupancy in forkhead box P1 (Foxp1) relevant to lipid metabolism upon glucocorticoid stress. Foxp1 interference downregulated adipogenic activities of glucocorticoid-treated cells. In vivo, treatment with BRD4 inhibitor JQ-1 compromised the glucocorticoid-induced bone mineral density loss, spare trabecular structure, and fatty marrow, as well as improved biomechanical properties of bone tissue.

Taken together, BRD4-mediated Foxp1 pathways drive mesenchymal stem cells shifting toward adipocytic cells rather than osteogenic cells to aggravates excessive marrow adipogenesis in the process of glucocorticoid-induced osteoporosis. Pharmacological inhibition of BRD4 signaling protects bone tissue from bone loss and fatty marrow in glucocorticoid-treated mice. This study conveys a new molecular insight into epigenetic regulation of osteogenesis and adipogenesis in osteoporotic skeleton and highlight the remedial effect of BRD4 inhibitor on glucocorticoid-induced bone loss.

Chronic glucocorticoid use causes osteogenesis loss, accelerating the progression of osteoporosis. Histone methylation is shown to epigenetically increase repressive transcription, altering lineage programming of mesenchymal stem cells (MSC). This study is undertaken to characterize the action of histone demethylase UTX to osteogenic lineage specification of bone-marrow MSC and bone integrity upon glucocorticoid treatment.

Bone-marrow MSC were incubated in osteogenic medium containing supraphysiological dexamethasone. Osteogenic gene expression and mineralized nodule formation were probed using RT-PCR and von Kossa staining. The enrichment of trimethylated lysine 27 at histone 3 (H3K27me3) in Dkk1 promoter was quantified using chromatin immunoprecipitation-PCR. Bone mass and trabecular morphometry in methylprednisolone-treated skeletons were quantified using microCT analysis.

Supraphysiological dexamethasone decreased osteogenic genes Runx2 and osteocalcin expression and mineralized matrix production along with reduced UTX expression in MSC. Forced UTX expression attenuated the glucocorticoid-mediated loss of osteogenic differentiation, whereas UTX knockdown provoked osteogenesis loss and cytoplasmic oil overproduction. UTX demethylated H3K27 and reduced the glucocorticoid-mediated the H3K27 enrichment in Dkk1 promoter, reversing beta-catenin signal, but downregulating Dkk1 production by MSC. In vivo, treatment with UTX inhibitor GSK-J4 significantly suppressed bone mineral density, trabecular volume, and thickness along with porous trabecular, fatty marrow and disturbed beta-catenin/Dkk1 histopathology comparable with glucocorticoid-induced osteoporosis condition.

This study offers a productive insight into how UTX protects MSC from methylated histone-mediated osteogenesis repression in the development of glucocorticoid-induced osteoporosis.

Aims

This study aimed to determine the minimal detectable change (MDC), minimal clinically important difference (MCID), and substantial clinical benefit (SCB) under distribution- and anchor-based methods for the Mayo Elbow Performance Index (MEPI) and range of movement (ROM) after open elbow arthrolysis (OEA). We also assessed the proportion of patients who achieved MCID and SCB; and identified the factors associated with achieving MCID.

Osteoporosis accounts for a leading cause of degenerative skeletal disease in the elderly. Osteoblast dysfunction is a prominent feature of age-induced bone loss. While microRNAs regulate osteogenic cell behavior and bone mineral acquisition, however, their function to osteoblast senescence during age-mediated osteoporosis remains elusive. This study aims to utilize osteoblast-specific microRNA-29a (miR-29a) transgenic mice to characterize its role in bone cell aging and bone mass.

Young (3 months old) and aged (9 months old) transgenic mice overexpressing miR-29a (miR-29aTg) driven by osteocalcin promoter and wild-type (WT) mice were bred for study. Bone mineral density, trabecular morphometry, and biomechanical properties were quantified using μCT imaging, material testing system and histomorphometry. Aged osteoblasts and senescence markers were probed using immunofluorescence, flow cytometry for apoptotic maker annexin V, and RT-PCR.

Significantly decreased bone mineral density, sparse trabecular morphometry (trabecular volume, thickness, and number), and poor biomechanical properties (maximum force and breaking force) along with low miR-29a expression occurred in aged WT mice. Aging significantly upregulated the expression of senescence markers p16INK4a, p21Waf/Cip1, and p53 in osteoporotic bone in WT mice. Of note, the severity of bone mass and biomechanical strength loss, as well as bone cell senescence, was remarkably compromised in aged miR-29aTg mice. In vitro, knocking down miR-29a accelerated senescent (β-galactosidase activity and senescence markers) and apoptotic reactions (capsas3 activation and TUNEL staining), but reduced mineralized matrix accumulation in osteoblasts. Forced miR-29a expression attenuated inflammatory cytokine-induced aging process and retained osteogenic differentiation capacity. Mechanistically, miR-29a dragged osteoblast senescence through targeting 3′-untranslated region of anti-aging regulator FoxO3 to upregulate that of expression as evident from luciferase activity assessment.

Low miR-29a signaling speeds up aging-induced osteoblast dysfunction and osteoporosis development. Gain of miR-29a function interrupts osteoblast senescence and shields bone tissue from age-induced osteoporosis. The robust analysis sheds light to the protective actions of miR-29a to skeletal metabolism and conveys a perspective of miR-29a signaling enhancement beneficial for aged skeletons.

Aberrant infrapatellar fat metabolism is a notable feature provoking inflammation and fibrosis in the progression of osteoarthritis (OA). Irisin, a secretory subunit of fibronectin type III domain containing 5 (FNDC5) regulate adipose morphogenesis, energy expenditure, skeletal muscle, and bone metabolism. This study aims to characterize the biological roles of Irisin signaling in an infrapatellar fat formation and OA development.

Injured articular specimens were harvested from 19 patients with end-stage knee OA and 11 patients with the femoral neck fracture. Knee joints in mice that overexpressed Irisin were subjected to intra-articular injection of collagenase to provoke OA. Expressions of Irisin, adipokines, and MMPs probed with RT-quantitative PCR. Infrapatellar adiposity, articular cartilage damage, and synovial integrity verified with histomorphometry and immunohistochemistry.

Infrapatellar adipose and synovial tissues instead of articular cartilage exhibited Irisin immunostaining. Human OA specimens showed 40% decline in Irisin expression than the non-OA group. In vitro, the gain of Irisin function enabled synovial fibroblasts but not chondrocytes to display minor responses to the IL-1β provocation of MMP3 and MMP9 expression. Of note, Irisin signaling reduced adipogenic gene expression and adipocyte formation of mesenchymal progenitor cells. In collagenase-mediated OA knee pathogenesis, forced FNDC5 expression in articular compromised the collagenase-induced infrapatellar adipose hypertrophy, synovial hypercellularity, and membrane hyperplasia. These adipose-regulatory actions warded off the affected knees from cartilage destruction and gait aberrance. Likewise, intra-articular injection of Irisin recombinant protein mitigated the development of infrapatellar adiposity and synovitis slowing down the progression of cartilage erosion and walking profile irregularity. Affected joints and adipocytes responded to the Irisin recombinant protein treatment by reducing the expressions of cartilage-deleterious adipokines IL-6, leptin, and adiponectin through regulating PPAR&gamma, function.

Irisin dysfunction is relevant to the existence of end-stage knee OA. Irisin signaling protects from excessive adipogenesis of mesenchymal precursor cells and diminished inflammation and cartilage catabolism actions aggravated by adipocytes and synovial cells. This study sheds emerging new light on the Irisin signaling stabilization of infrapatellar adipose homeostasis and the perspective of the therapeutic potential of Irisin recombinant protein for deescalating knee OA development.

Aims

Inflammatory response plays a pivotal role in the pathophysiological process of intervertebral disc degeneration (IDD). A20 (also known as tumour necrosis factor alpha-induced protein 3 (TNFAIP3)) is a ubiquitin-editing enzyme that restricts nuclear factor-kappa B (NF-κB) signalling. A20 prevents the occurrence of multiple inflammatory diseases. However, the role of A20 in the initiation of IDD has not been elucidated. The aim of the study was to investigate the effect of A20 in senescence of TNF alpha (TNF-α)-induced nucleus pulposus cells (NPCs).

Chondrocyte dysfunction is attributable to the development of osteoarthritis (OA). Deregulation of chondrogenic regulators and deleterious factors, e.g. proteinases, Wnt signalling components, and autophagy repressors lowers chondrogenic activities and ultimately deteriorates cartilage homeostasis. Emerging evidence is that epigenetic pathways, including non-coding microRNAs and histone remodelling switch on/off the expression of joint-deleterious factors. MicroRNAs reduces the expressions of mRNAs through binding to the 3'-untranslation regions of targets. The levels of microRNAs, e.g. miR-29a, miR-128a in serum, synovial fluid, synovium, and cartilage are correlated with the occurrence of OA. Mice overexpressing/deficient microRNAs of interest show minor responses to OA progression. Besides, acetylation and methylation statuses of histones regulate the factors detrimental to chondrocytes through altering the interactions between histones and promoters. Histone deacetylases and demethylases, e.g. HDAC4, SIRT1, and EZH2 contribute to the modification reactions of histones, which modulate cartilage matrix metabolism. An intricate nature is that reciprocal actions between microRNAs and histone deacetylase/demethylase are indispensable in chondrocyte survival and function. Administrations with specific inhibitor/agonists for microRNAs and histone deacetylases/demethylase enable joints to show minor responses to articular injury, which mitigate the pathogenesis of OA. This talk highlights the biological roles and therapeutic advantage of epigenetic microRNAs and histone remodelling in OA.

Sclerostin (SOST) is an endogenous inhibitor of Wnt/β-catenin signalling pathway to impair osteogenic differentiation and bone anabolism. SOST immunotherapy like monoclonal antibody has been observed to control bone remodeling and regeneration. This study is aimed to develop a SOST vaccine and test its protective effects on estrogen deficiency-induced bone loss in mice. Gene sequences coded SOST peptide putative targeting Wnt co-receptor LRP5 were cloned and constructed into vectors expressing Fc fragment to produced SOST-Fc fusion protein. Mice were subcutaneously injected SOST-Fc to boost anti-SOST antibody. Bone mineral density, microstructure, and mechanical property were quantified using μCT scanning and material testing system. Serum bone formation and resorption markers and anti-SOST levels were measured using ELISA. SOST-Fc injections significantly increased serum anti-SOST antibody levels but reduced serum SOST concentrations. SOST-Fc vaccination significantly reduced estrogen deficiency-induced serum bone resorption markers CTX-1 increased serum bone formation marker osteocalcin. Of note, it significantly alleviated the severity of estrogen-induced loss of bone mineral density, trabecular morphometric properties, and biomechanical forces of bone tissue. Mechanistically, SOSF-Fc vaccination attenuated trabecular loss histopathology and restored immunostaining of Wnt pathway like Wnt3a, β-catenin, and TCF4 in bone tissue along with increased serum osteoclast inhibitor OPG levels but decreased serum osteoclast enhancer RANKL concentrations. Taken together, SOST-Fc vaccination boosts anti-SOST antibody to neutralize SOST and mitigates the estrogen deficiency-induced bone mass and microstructure deterioration through preserving Wnt signalling. This study highlights an innovative remedial potential of SOST vaccine for preventing osteoporosis.

Subacromial bursa fibrosis are linked to rotator cuff lesion with shoulder stiffness; however, the mechanism underlying this shoulder disorder remain elusive. MicroRNA-29s (miR-29s) are emerging fibrosis inhibitor targeting fibrogenic matrices during tissue fibrosis. This study is aimed to investigate clinical relevance and function of miR-29 signalling to subacromial bursa homeostasis in shoulder stiffness. Subacromial bursa in patients with rotator cuff lesion with or without shoulder stiffness who required open acromioplasty were harvested for assessing fibrosis histopathology using Manson's trichrome staining. Expressions of proinflammatory cytokines, fibrotic matrices, and miR-29s were quantified using RT-PCR and in situ hybridization. Range of motion and pain scores of the stiffness group were higher than those of non-stiffness group. Upregulated proinflammatory cytokines (IL-1β, IL-6, and TNF-α) and fibrotic matrices (collagen 1α1, 3α1, and 4α1) but decreased miR-29a and b expression existed in the stiffness group. Affected tissues exhibited severe fibrotic matrix accumulation, synovial hyperangiogenesis, hyperplasia, and strong miR-29a transcripts. In vitro, IL-1β rather than IL-6 and TNF-α decreased miR-29a expression of subacromial bursa fibroblasts. miR-29a knockdown escalated fibrotic matrix expression, whereas forced miR-29a expression alleviated the IL-1β-induced fibrotic matrix expression. Of interest, miR-29a transgenic mice displayed moderate responses to supraspinatus and infraspinatus tenotomy-induce fibrosis and gait irregularity of affected shoulders. Weak miR-29 signalling causes excessive fibrosis and remodelling in subacromial bursa and ultimately increases the prevalence of shoulder stiffness. This study reveals a new mechanistic underlying shoulder stiffness and highlights that sustained miR-29a potentially ameliorates the severity and function of stiff shoulder.