A Prospective Assessment of Periprosthetic Bone Mineral Density and Osteoimmunological Biomarkers Variations After Total Knee Replacement Surgery.

Aseptic loosening is a major cause of premature failure of total knee replacement (TKR). Variations in periprosthetic bone mineral density (BMD) and osteoimmunological biomarkers levels could help to quantify prosthesis osteointegration and predict early aseptic loosening. The gene expression of 5 selected osteoimmunological biomarkers was evaluated in tibial plateau bone biopsies by real-time polymerase chain reaction and changes in their serum levels after TKR were prospectively evaluated with enzyme-linked immunosorbent assay for 1 yr after surgery. These variations were correlated to changes in periprosthetic BMD. Sixteen patients were evaluated. A statistically significant decrease in serum levels of Sclerostin (p = 0.0135) was observed immediately after surgery. A specular pattern was observed between dickkopf-related protein 1 and osteoprotegerin expression. No statistically significant changes were detectable in the other study biomarkers. Periprosthetic BMD did not change significantly across the duration of the follow-up. Prosthetic knee surgery has an impact on bone remodeling, in particular on sclerostin expression. Although not showing statistically significant changes, in the patterns of dickkopf-related protein 1, osteoprotegerin, and the ligand of the receptor activator of nuclear factor kappa-B symmetries and correspondences related to the biological activities of these proteins could be identified. Variation in osteoimmunological biomarkers after TKR surgery can help in quantifying prosthesis osteointegration.

Vitamin E-stabilized UHMWPE: Biological response on human osteoblasts to wear debris.

UHMWPE doped with vitamin E was introduced to provide oxidation resistance upon sterilization, without affecting UHMWPE's mechanical properties. Particle-induced macrophage activation leads to periprosthetic bone resorption, requiring total joint replacements. During osteolysis, osteoblasts produce osteoimmunological factors such as RANKL and OPG, and the inhibitors of the Wnt pathway DKK-1 and Sclerostin. This study investigated in vitro how vitamin E-blended-UHMWPE wear debris might affect osteoblast-mediated osteolysis and the production of RANKL, OPG, Sclerostin and DKK-1, compared to conventional UHMWPE wear debris. Human osteoblastic SaOS2 cells were incubated with wear particles from Vitamin E doped and conventional UHMWPE and the gene expression and protein production of IL-6, RANKL, OPG, DKK-1, and Sclerostin was evaluated, RANKL, a bone erosion marker, was reduced, while OPG, a bone protective marker, were increased by the vitamin E-blended UHMWPE compared to conventional UHMWPE. Vitamin E doped UHMWPE reduced Sclerostin level, and partially affected DKK-1 production, thereby protecting against bone erosion. In conclusion, Vitamin E-blended UHMWPE induced an osteoimmunological response in bone cells that had positive effects on the osteolysis induced by wear debris, reducing aseptic loosening of the implants. In conclusion, this is the first study showing that Vitamin E-blended UHMWPE induced an osteoimmunological response in bone cells that positively affect the osteolysis induced by wear debris, thereby reducing the aseptic loosening of the implants.

Presepsin: A potential biomarker of PJI? A comparative analysis with known and new infection biomarkers.

There is still no "gold standard" for the diagnosis and prognosis of post-operative periprosthetic joint infection (PJI). Among serum biomarkers, an emerging molecule is presepsin, the soluble fraction of CD14, recently described in other settings as a powerful diagnostic tool to detect sepsis at different degrees of severity. The aim of this study was to investigate the diagnostic and prognostic value of presepsin in PJI. A total of 30 patients with PJI and 30 patients without PJI were enrolled. Presepsin, C-reactive protein (CRP), serum interleukin (IL)-6, triggering receptor expressed on myeloid cells 1 (TREM-1), CCL2, matrix metalloproteinase 9 (MMP-9), CD163, osteopontin (OPN), and toll-like receptor 2 (TLR2) were measured at different times after surgery. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were analyzed for each biomarker. Presepsin showed greater diagnostic value than CRP and IL-6; CD163, TREM-1, and MMP-9 had very low diagnostic potential. Presepsin, OPN, CCL2, suPAR, and TLR2 all decreased significantly with increasing time of recovery after surgery in PJI patients. Presepsin can be considered a useful tool for the diagnosis and clinical monitoring of PJI and can be backed by a panel of new inflammatory markers involved in monocyte-/macrophage-mediated inflammatory responses, such as OPN, CCL2, TLR2, and suPAR.

Evaluation of circulating sRAGE in osteoporosis according to BMI, adipokines and fracture risk: a pilot observational study.

BACKGROUND: Osteoporosis is a systemic metabolic disease based on age-dependent imbalance between the rates of bone formation and bone resorption. Recent studies on the pathogenesis of this disease identified that bone remodelling impairment, at the base of osteoporotic bone fragility, could be related to protein glycation, in association to oxidative stress. The glycation reactions lead to the generation of glycation end products (AGEs) which, in turn, accumulates into bone, where they binds to the receptor for AGE (RAGE). The aim of this study is to investigate the potential role of circulating sRAGE in osteoporosis, in particular evaluating the correlation of sRAGE with the fracture risk, in association with bone mineral density, the fracture risk marker FGF23, and lipid metabolism. RESULTS: Circulating level of soluble RAGE correlate with osteopenia and osteoporosis level. Serum sRAGE resulted clearly associated on the one hand to bone fragility and, on the other hand, with BMI and leptin. sRAGE is particularly informative because serum sRAGE is able to provide, as a single marker, information about both the aspects of osteoporotic disease, represented by bone fragility and lipid metabolism. CONCLUSIONS: The measure serum level of sRAGE could have a potential diagnostic role in the monitoring of osteoporosis progression, in particular in the evaluation of fracture risk, starting from the prevention and screening stage, to the osteopenic level to osteoporosis.

RNA isolation from alveolar bone and gene expression analysis of RANK, RANKL and OPG: A new tool to monitor bone remodeling and healing in different bone substitutes used for prosthetic rehabilitation.

OBJECTIVE: (i) To validate a simple and efficient method for extracting high quality RNA from small samples of bone tissue, (ii) to test its application on limited amounts of grafted oral bone and (iii) to analyze the gene expression of the OPG/RANK/RANKL system and IL-6 in "spontaneous healing" and grafted tissue. DESIGN: 26 patients in need of extraction of one lower molar tooth were divided in 3 groups. In group A (8 patients) the alveolar socket was left for spontaneous healing, in group B (8 patients) it was filled with a hydroxyapatite scaffold while in group C (10 patients) it was filled with hydroxyapatite granules. A small amount of bone was scraped from the alveolar site and sent for analysis. Four months later a new bone specimen was harvested during implant bed preparation. RESULTS: IL-6 increased over time in all groups and in particular to the grafted groups. RANK, RANKL and OPG increased over time in all groups, except for RANK in group B. The RANKL/OPG ratio showed a negative value in group A and even more in group B, while it was positive in group C. CONCLUSIONS: The alveolar site grafted with a granular biomaterial behaved similar to the physiological healing group but displayed a slow remodeling process. RANK, RANKL, OPG and the RANKL/OPG ratio might be able to distinguish among different biomaterials and represent different healing patterns according to different clinical conditions.

Plasmatic Soluble Receptor for Advanced Glycation End Products as a New Oxidative Stress Biomarker in Patients with Prosthetic-Joint-Associated Infections?

Prosthetic joint infection (PJI) is the most common cause of failure of total joint arthroplasty, but a gold standard for PJI diagnosis is still lacking. Advanced glycation end products (AGEs) are proinflammatory molecules inducing intracellular oxidative stress (OS) after binding to their cell membrane receptors (RAGE). The aim of this study was to evaluate plasmatic soluble receptor for advanced glycation end products (sRAGE), as a new OS and infection marker correlating sRAGE to the level of OS and antioxidant defenses, in PJI, in order to explore the possible application of this new biomarker in the early diagnosis of PJI. Plasmatic sRAGE levels (by ELISA assay), plasma antioxidant total defenses (by lag time method), plasma reactive oxygen species (ROS), and thiobarbituric acid reactive substance (TBARS) levels (by colorimetric assay) were evaluated in 11 PJI patients and in 30 matched controls. ROS and TBARS were significantly higher (p < 0.001) while plasma total antioxidant capacity and sRAGE were significantly lower (p < 0.01) in patients with PJI compared to controls. Our results confirm the OS in PJI and show a strong negative correlation between the level of sRAGE and oxidative status, suggesting the plasmatic sRAGE as a potential marker for improving PJI early diagnosis.

Proinsulin C-peptide modulates the expression of ERK1/2, type I collagen and RANKL in human osteoblast-like cells (Saos-2).

A lower bone mass accompanied by a higher bone fragility with increased risk of fracture are observed in individuals with type 1 diabetes mellitus. Low C-peptide levels are associated with low lumbar mineral density in postmenopausal woman. In this work, we investigated the role of C-peptide on the osteoblast cell biology in vitro. We examined intracellular pathways and we found that C peptide activates ERK1/2 in human osteoblast-like cells (Saos-2). We also observed that proinsulin C-peptide prevents a reduction of type I collagen expression and decreases, in combination with insulin, receptor activator of nuclear factor-κB (RANKL) levels. In this work we show for the first time that Cpeptide activates a specific intracellular pathway in osteoblasts and it modulates the expression of protein involved in bone remodeling. Our results suggest that both C-peptide may have a role in bone metabolism. Further studies are needing to fully clarify its role.

Soluble urokinase-type plasminogen activator receptor (suPAR) as new biomarker of the prosthetic joint infection: correlation with inflammatory cytokines.

Post-operative prosthetic joint infection (PJI) is the most common cause of failure of total joint arthroplasty, requiring revision surgery, but a gold standard for the diagnosis and the treatment of PIJ is still lacking. PJI is mainly due to Gram-positive bacteria, in particular, Staphylococcus Aureus, and more rarely by Gram-negative bacteria such as Pseudomonas. This study aimed to examine the diagnostic value of SuPAR in post-operative PJI, in order to explore the possible application of this new biomarker in the early diagnosis of PJI. The level of SuPAR has been measured in PJI patients and healthy controls, correlated with canonical inflammatory markers, such as C-reactive protein, IL-6, IL-1 and TNFα and the chemokine CCL2. Serum suPAR displayed a strongly significative increase in PJI patients compared to not infected controls, and a significative positive correlation with C-reactive protein, IL-6, IL-1 and TNFα and the chemokine CCL2. Also serum CCL2 showed statistically significative increase in PJI patients, and it displayed a strong positive correlation with serum suPAR. This study provides a clear indication of the diagnostic potential of suPAR, in association to routine inflammatory parameters such as CRP, in the diagnosis of PJI.

Soft-focused extracorporeal shock waves increase the expression of tendon-specific markers and the release of anti-inflammatory cytokines in an adherent culture model of primary human tendon cells.

Focused extracorporeal shock waves have been found to upregulate the expression of collagen and to initiate cell proliferation in healthy tenocytes and to positively affect the metabolism of tendons, promoting the healing process. Recently, soft-focused extracorporeal shock waves have also been found to have a significant effect on tissue regeneration. However, very few in vitro reports have dealt with the application of this type of shock wave to cells, and in particular, no previous studies have investigated the response of tendon cells to this impulse. We devised an original model to investigate the in vitro effects of soft-focused shock waves on a heterogeneous population of human resident tendon cells in adherent monolayer culture. Our results indicate that soft-focused extracorporeal shock wave treatment (0.17 mJ/mm(2)) is able to induce positive modulation of cell viability, proliferation and tendon-specific marker expression, as well as release of anti-inflammatory cytokines. This could prefigure a new rationale for routine employment of soft-focused shock waves to treat the failed healing status that distinguishes tendinopathies.

Hypertension in adult Fabry's disease: is cardiotrophin-1 a diagnostic biomarker?

BACKGROUND: Cardiotrophin-1 (CT-1), a cytokine produced by cardiomyocytes and non-cardiomyocytes in conditions of stress, can be used as a biomarker of left ventricular hypertrophy and dysfunction in hypertensive patients. Hypertension is one of the main adverse events in the third and last phase of Fabry's disease (FD). We measured CT-1 in order to examine its correlation with the vascular and cardiac alterations at different ages and assess its potential for use as a biomarker of hypertension in FD. FINDINGS: The level of CT-1 was clearly higher in hypertensive adults than in adult FD patients. FD patients show a small, non-significant decrease in plasma CT-1 with age, while in hypertensive patients CT-1 in plasma rises strongly and highly significantly with age. CONCLUSIONS: CT-1 can be considered a good biomarker of the progression of hypertension with age, but particular care is needed when following hypertension in FD patients, since CT-1 does not correlate the same way with this disease.