Expression of ICAM-1 by osteoblasts in healthy individuals and in patients suffering from osteoarthritis and osteoporosis

The characterization and comparison of femoral bone-derived skeletal stem cells

Skeletal stem cells (SSCs) reside in various niche locations within long bones to maintain bone homeostasis and facilitate fracture repair. Bone fragility, associated with ageing, increases the susceptibility of the femoral head to fractures due to an increase in bone adipocytes and concomitant loss of structural integrity. However, the specific contribution of epiphyseal SSCs to fragility is unknown. To explore this, a comparative analysis was performed on the transcriptional profiles and lineage commitment of Wistar rat femoral SSCs derived from the bone marrow (BM-), diaphyseal cortical bone (CB-) and proximal epiphyseal trabecular bone (PF-SSCs) isolated from the same long bones. SSCs were characterized based on morphology, immunophenotype (CD90/CD45), growth rate (population doubling time), gene expression profiles and differentiation capacity (Oil Red O, Alizarin Red S). qRT-PCR micro-arrays were performed on SSCs to evaluate the expression of stemness, SSC and lineage-specific markers in both undifferentiated and differentiated states. Our findings support the hypothesis that SSCs from different bone regions exhibit distinct transcriptional profiles, reflecting their specific niche environments. CB-SSCs displayed superior osteogenic potential as evidenced by the expression of key osteogenic genes and higher levels of mineralization. In contrast, PF-SSCs had a reduced osteogenic capacity with a higher adipogenic potential. Overall, the study revealed the importance of niche-specific stem cell properties for use in regenerative medicine applications and provides insight into the potential role of PF-SSCs in bone fragility and fracture risk.

Serum lncRNA ITGB2-AS1 and ICAM-1 as novel biomarkers for rheumatoid arthritis and osteoarthritis diagnosis

BACKGROUND

The complete circulating long non-coding RNAs (lncRNAs) signature of rheumatoid arthritis (RA) and osteoarthritis (OA) is still uncovered. The lncRNA integrin subunit beta 2 (ITGB2)-anti-sense RNA 1 (ITGB2-AS1) affects ITGB2 expression; however, there is a gap in knowledge regarding its expression and clinical usefulness in RA and OA. This study investigated the potential of serum ITGB2-AS1 as a novel diagnostic biomarker and its correlation with ITGB2 expression and its ligand intercellular adhesion molecule-1 (ICAM-1), disease activity, and severity in RA and primary knee OA patients.

SUBJECTS

Forty-three RA patients, 35 knee OA patients, and 22 healthy volunteers were included.

RESULTS

Compared with healthy controls, serum ITGB2-AS1 expression was upregulated in RA patients but wasn't significantly altered in knee OA patients, whereas serum ICAM-1 protein levels were elevated in both diseases. ITGB2-AS1 showed discriminative potential for RA versus controls (AUC = 0.772), while ICAM-1 displayed diagnostic potential for both RA and knee OA versus controls (AUC = 0.804, 0.914, respectively) in receiver-operating characteristic analysis. In the multivariate analysis, serum ITGB2-AS1 and ICAM-1 were associated with the risk of developing RA, while only ICAM-1 was associated with the risk of developing knee OA. A panel combining ITGB2-AS1 and ICAM-1 showed profound diagnostic power for RA (AUC = 0.9, sensitivity = 86.05%, and specificity = 91.67%). Interestingly, serum ITGB2-AS1 positively correlated with disease activity (DAS28) in RA patients and with ITGB2 mRNA expression in both diseases, while ICAM-1 positively correlated with ITGB2 expression in knee OA patients.

CONCLUSION

Our study portrays serum ITGB2-AS1 as a novel potential diagnostic biomarker of RA that correlates with disease activity. A predictive panel combining ITGB2-AS1 and ICAM-1 could have clinical utility in RA diagnosis. We also spotlight the association of ICAM-1 with knee OA diagnosis. The correlation of serum ITGB2-AS1 with ITGB2 expression in both diseases may be insightful for further mechanistic studies.

Exploring the mechanism of action of Vanda tessellata extract for the treatment of osteoarthritis through network pharmacology, molecular modelling and experimental assays

The present study employed a comprehensive approach of network pharmacology, molecular dynamic simulation and in-vitro assays to investigate the underlying mechanism of the anti-osteoarthritic potential of Vanda tessellata extract (VTE). Thirteen active compounds of VTE were retrieved from the literature and the IMPPAT database. All of these passed the drug likeness and oral bioavailability parameters. A total of 535 VTE targets and 2577 osteoarthritis related targets were obtained. The compound-target-disease network analysis revealed vanillin, daucosterol, gigantol and syringaldehyde as the core key components. Protein-protein interaction analysis revealed BCL2, FGF2, ICAM 1, MAPK1, MMP1, MMP2, MMP9, COX2, STAT3 and ESR1 as the hub genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed AGE-RAGE signalling pathway, HIF-1 signalling pathway and ESR signalling pathway as the major signalling pathway of VTE involved in treating osteoarthritis. Molecular docking analysis showed daucosterol and gigantol to have good binding affinity with BCL2, ESR1 and MMP9, and the results were further confirmed through molecular dynamics simulation analysis. The mechanism predicted by network pharmacology was validated in vitro on IL-1β-induced SW982 synovial cells. VTE did not show any cytotoxicity and inhibited the migration of SW982 cells. VTE inhibited the expression level of IL-6, IL-8, TNF-α, PGE-2, MMP-2 and MMP-9 in a dose-dependent manner. VTE inhibited nuclear translocation of NF- κβ and suppressed phosphorylation of p38, extracellular signal-regulated kinase (ERK), and c-Jun NH2-terminal kinase (JNK) of the mitogen-activated protein kinase (MAPK) signalling pathway. The results showed that VTE exerted an anti-osteoarthritic effect by a multi-target, multi-component and multi-signalling pathway approach.

Identification of 12 hub genes associated to the pathogenesis of osteoporosis based on microarray and single-cell RNA sequencing data

Osteoporosis is a common disease, especially among the elderly. This study aimed to comprehensively examine the roles of immune microenvironment in osteoporosis pathogenesis. Expression profiles of GSE35959, GSE7158, and GSE13850 datasets were used to analyze differential expression and identify hub genes related to immune features. Based on the single-cell RNA sequencing (scRNA-seq) data of an osteoporosis patient, different cell types were classified and the relation between immune environment and osteoporosis was explored. Twelve hub genes significantly associated with immune features were selected and 11 subgroups were defined using scRNA-seq data. The expression of two hub genes (CDKN1A and TEFM) was greatly altered during the transformation from mesenchymal stem cells (MSCs) to osteoblasts. Chemokines and chemokine receptors were differentially enriched in different cell types. CXCL12 was high-expressed in MSCs. This study emphasized that immune microenvironment played a critical role in the pathogenesis of osteoporosis. Chemokines and chemokine receptors can modify cell development and affect the interactions among different cell types, leading to unbalanced bone remodeling.

ICAM-1-mediated osteoblast-T lymphocyte direct interaction increases mineralization through TGF-β1 suppression

Modulation of osteoblast functions by T lymphocytes is important in inflammation-associated mineralized tissue diseases. The study aimed to determine whether direct interaction between these two cell types affects osteoblast functions and mineralization. The results showed that direct contact between the two cell types was evident by scanning electron microscopy and transmission electron microscopy. Under osteogenic induction, higher hydroxyapatite precipitation was observed in cocultures with direct contact with T lymphocytes compared with that by osteoblasts cultured alone. Cocultures without direct cell contact caused a decrease in mineralization. Direct cell contact also upregulated intercellular adhesion molecule (ICAM)-1 and simultaneously downregulated transforming growth factor (TGF)-β1 in osteoblasts. However, the downregulation of TGF-β1 was reversed by ICAM-1 blocking. Exogenously added TGF-β1 in cocultures with direct cell contact suppressed mineralization. In conclusion, studies are consistent with ICAM-1-mediated direct contact between osteoblasts and T lymphocytes increasing mineralization via downregulation of TGF-β1 in osteoblasts in vitro. This suggests a possible unexpected, but crucial, role of T lymphocytes in enhancing matrix mineralization during the repair process in vivo. The study identifies ICAM-1/TGF-β1 as possible novel therapeutic targets for the treatment and prevention of inflammation-associated mineralized tissue diseases.

Natural Approach in Osteoarthritis Therapy

Osteoarthritis (OA) is the most common joint disease worldwide, and its rising prevalence is supported by factors such as obesity and sedentariness. At the molecular level, it is considered an inflammatory disease that leads to the destruction of articular cartilage. Effective therapy to end the degenerative process of arthritis remains elusive, and most therapeutic tools prevent the progress or alleviate the symptoms. By now, medicines for OA are available for oral, topical, or intra-articular (IA) therapy and include analgesics, nonsteroidal anti-inflammatory drugs, corticosteroids, and hyaluronic acid. Compared with conventional oral administration, IA therapy has multiple advantages in terms of bioavailability, efficacy, and toxicity. This review aims to study the underlying beneficial effects of herbal medicine in OA therapy and to open new research perspectives. Herbal medicine administered orally or topically exhibits pharmacological properties that could be relevant for their beneficial effect in OA, mainly anti-inflammatory and antioxidant effects. There are few studies regarding IA injections of plant extracts/ compounds and none related to any combination with agents already used in the clinic. Designing natural pharmaceutical formulations with increased bioavailability that are safe, lack side effects, and are specifically tested, would be a plus for research on medicinal plants and a novelty for the clinic.

Ni and TiO2 nanoparticles cause adhesion and cytoskeletal changes in human osteoblasts

Titanium-based alloys have established a crucial role in implantology. As material deteriorates overtime, nanoparticles of TiO₂ and Ni are released. This study is focused on the impact of TiO₂ and Ni nanoparticles with size of 100 nm on cytoskeletal and adhesive changes in human physiological and osteoarthritic osteoblasts. The impact of nanoparticles with concentration of 1.5 ng/mL on actin and tubulin expression and gene expression of FAK and ICAM-1 was studied. The cell size and actin expression of physiological osteoblasts decreased in presence of Ni nanoparticles, while TiO₂ nanoparticles caused increase in cell size and actin expression. Both cell lines expressed more FAK as a response to TiO₂ nanoparticles. ICAM-1 gene was overexpressed in both cell lines as a reaction to both types of nanoparticles. The presented study shows a crucial role of Ni and TiO₂ nanoparticles in human osteoblast cytoskeletal and adhesive changes, especially connected with the osteoarthritic cells. Graphical abstract.

Visfatin increases ICAM-1 expression and monocyte adhesion in human osteoarthritis synovial fibroblasts by reducing miR-320a expression

Pathophysiological events that modulate the progression of structural changes in osteoarthritis (OA) include monocyte adhesion and infiltration, and synovial inflammation. In particular, the adhesion protein intercellular adhesion molecule type 1 (ICAM-1) promotes monocyte recruitment into the synovial tissue. Visfatin is an adipocyte hormone that promotes the release of inflammatory cytokines during OA progression. We report that visfatin enhances ICAM-1 expression in human OA synovial fibroblasts (OASFs) and facilitates the adhesion of monocytes with OASFs. AMPK and p38 inhibitors, as well as their respective siRNAs, attenuated the effects of visfatin upon ICAM-1 synthesis and monocyte adhesion. We also describe how miR-320a negatively regulates visfatin-induced promotion of ICAM-1 expression and monocyte adhesion. We detail how visfatin affects ICAM-1 expression and monocyte adhesion with OASFs by inhibiting miR-320a synthesis via the AMPK and p38 signaling pathways.

Skeletal stem cell-mediated suppression on inflammatory osteoclastogenesis occurs via concerted action of cell adhesion molecules and osteoprotegerin

In the current study, we investigated how skeletal stem cells (SSCs) modulate inflammatory osteoclast (OC) formation and bone resorption. Notably, we found that intercellular adhesion molecule‐1 (ICAM‐1), vascular cell adhesion molecule‐1 (VCAM‐1), and osteoprotegerin (OPG) play a synergistic role in SSC‐mediated suppression of inflammatory osteoclastogenesis. The effect of SSCs on inflammatory osteoclastogenesis was investigated using a lipopolysaccharide‐induced mouse osteolysis model in vivo and human osteoarthritis synovial fluid (OASF) in vitro. OC formation was determined by tartrate‐resistant acid phosphatase staining. Bone resorption was evaluated by microcomputerized tomography, serum C‐terminal telopeptide assay, and pit formation assay. The expression of ICAM‐1, VCAM‐1, and OPG in SSCs and their contribution to the suppression of osteoclastogenesis were determined by flow cytometry or enzyme linked immunosorbent assay. Gene modification, neutralization antibodies, and tumor necrosis factor‐α knockout mice were used to further explore the mechanism. The results demonstrated that SSCs remarkably inhibited inflammatory osteoclastogenesis in vivo and in vitro. Mechanistically, inflammatory OASF stimulated ICAM‐1 and VCAM‐1 expression as well as OPG secretion by SSCs. In addition, ICAM‐1 and VCAM‐1 recruited CD11b⁺ OC progenitors to proximity with SSCs, which strengthened the inhibitory effects of SSC‐derived OPG on osteoclastogenesis. Furthermore, it was revealed that tumor necrosis factor α is closely involved in the suppressive effects. In summary, SSCs express a higher level of ICAM‐1 and VCAM‐1 and produce more OPG in inflammatory microenvironments, which are sufficient to inhibit osteoclastogenesis in a “capture and educate” manner. These results may represent a synergistic mechanism to prevent bone erosion during joint inflammation by SSCs.

Peptide-biofunctionalization of biomaterials for osteochondral tissue regeneration in early stage osteoarthritis: challenges and opportunities

Osteoarthritis is a degenerative joint disease characterized by the progressive deterioration of articular cartilage, synovial inflammation and changes in periarticular and subchondral bone, being a leading cause of disability.

Neuroimmune expression in hip osteoarthritis: a systematic review

BACKGROUND

Neuroimmune axis is central in the physiopathology of hip osteoarthritis (OA), but its specific pathways are still unclear. This systematic review aims to assess the nervous and immune system profile of patients with hip osteoarthritis (OA) when compared to healthy controls.

METHODS

A systematic review followed PRISMA guidelines was conducted. A two-step selection process was completed, and from 609 references 17 were included. The inclusion criteria were: original articles on adult patients with hip OA, with assessment of neuroimmune expression. Articles with other interventions prior to analysis and those without a control group were excluded.

RESULTS

Thirty-nine relevant neuroimmune markers were identified, with assessments in bone, cartilage, synovial membrane, synovial fluid, whole blood, serum and/or immune cells. GM-CSF, IFN-γ, IL-1α, IL-6, IL-8, IL-1 and TNF-α presented variable expression among tissues studied when compared between hip OA and controls. VEGFs and TGF-ß isoforms showed similar tendencies among tissues and studies. On nervous expression, CGRP, Tuj-1 and SP were increased in synovial membrane. Overall, patients with hip OA presented a higher number of overexpressed markers.

CONCLUSIONS

For the first time a systematic review on neuroimmune expression in patients with hip OA found an upregulation of neuroimmune markers, with deregulated balance between pro and anti-inflammatory cytokines. However, no clear systematic pattern was found, and few information is available on nervous expression. This highlights the importance of future research with clear methodologies to guide the management of these patients.

Circulating C reactive protein in osteoarthritis: a systematic review and meta-analysis

BACKGROUND

There is emerging evidence that the development and progression of osteoarthritis (OA) is associated with inflammation. C reactive protein (CRP), a systemic marker for inflammation, may be elevated in OA patients but the evidence is conflicting.

OBJECTIVE

To systematically review the literature for the relationship between serum CRP levels measured by a high sensitivity method (high sensitive CRP (hs-CRP)) and OA, as well as the correlation between circulating CRP levels and OA phenotypes.

METHODS

MEDLINE, EMBASE and CINAHL databases were systematically searched from January 1992 to December 2012. Studies were included when they met the inclusion criteria and data from studies were extracted. Two independent reviewers assessed study quality using a modified Newcastle-Ottawa Quality Assessment Scale. Meta-analyses were performed to pool available data from included studies.

RESULTS

32 studies met the inclusion criteria. Serum hs-CRP levels in OA were modestly but statistically significantly higher than controls (mean difference=1.19 mg/L, 95% CI 0.64 to 1.73, p<0.001) with significant heterogeneity between studies. Levels were significantly associated with pain (r=0.14, 95% CI 0.09 to 0.20, p<0.001) and decreased physical function (r=0.25, 95% CI 0.13 to 0.39, p<0.001). No significant associations were found between hs-CRP levels and radiographic OA.

CONCLUSIONS

Low-grade systemic inflammation may play a greater role in symptoms rather than radiographic changes in OA.

Evaluation of the anti-inflammatory/chondroprotective activity of aldose reductase inhibitors in human chondrocyte cultures

2-Thioxo-4-thiazolidinone derivatives active as aldose reductase inhibitors were able to control key inflammatory/degenerative events induced by IL-1β in human chondrocytes, appearing to be promising candidates in the search for novel anti-inflammatory agents.

Adiponectin enhances intercellular adhesion molecule-1 expression and promotes monocyte adhesion in human synovial fibroblasts

Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes and is involved in energy homeostasis. Adiponectin expression is significantly high in the synovial fluid of patients with osteoarthritis (OA). Intercellular adhesion molecule-1 (ICAM-1) is an important adhesion molecule that mediates monocyte adhesion and infiltration during OA pathogenesis. Adiponectin-induced expression of ICAM-1 in human OA synovial fibroblasts (OASFs) was examined by using qPCR, flow cytometry and western blotting. The intracellular signaling pathways were investigated by pretreated with inhibitors or transfection with siRNA. The monocyte THP-1 cell line was used for an adhesion assay with OASFs. Stimulation of OASFs with adiponectin induced ICAM-1 expression. Pretreatment with AMP-activated protein kinase (AMPK) inhibitors (AraA and compound C) or transfection with siRNA against AMPKα1 and two AMPK upstream activator- liver kinase B1 (LKB1) and calmodulin-dependent protein kinase II (CaMKII) diminished the adiponectin-induced ICAM-1 expression. Stimulation of OASFs with adiponectin increased phosphorylation of LKB1, CaMKII, AMPK, and c-Jun, resulting in c-Jun binding to AP-1 element of ICAM-1 promoter. In addition, adiponectin-induced activation of the LKB1/CaMKII, AMPK, and AP-1 pathway increased the adhesion of monocytes to the OASF monolayer. Our results suggest that adiponectin increases ICAM-1 expression in human OASFs via the LKB1/CaMKII, AMPK, c-Jun, and AP-1 signaling pathway. Adiponectin-induced ICAM-1 expression promoted the adhesion of monocytes to human OASFs. These findings may provide a better understanding of the pathogenesis of OA and can utilize this knowledge to design a new therapeutic strategy.

Regulation of the osteoblastic and chondrocytic differentiation of stem cells by the extracellular matrix and subsequent bone formation modes

While various factors have been reported to direct stem cell differentiation lineage, little is known about how nature orchestrates the mesenchymal stem cell (MSC) differentiation and bone morphogenesis during skeleton development and bone regeneration. The present study reports that the matrix has a critical regulating effect on MSC differentiation and the subsequent bone formation modes. A simply combined hydroxyapatite (HA)-collagen matrix stimulates the MSC differentiation into the osteoblastic lineage and leads to a straightforward intramembranous bone formation mode, in contrast to the chondrocytic differentiation and endochondral mode observed on HA-synthetic hydrogel matrix. The accelerated MSC condensation and robust MSC-matrix and MSC-MSC interactions on collagen-based matrix might be the critical factors contributing to such events, likely through the orchestrated signal cascades and cellular events modulated by the extracellular matrix. The results demonstrate that matrix plays critical role in modulating the stem cell differentiation lineage and bone formation mode, which has been largely overlooked.

Cell adhesion molecule 1 is a new osteoblastic cell adhesion molecule and a diagnostic marker for osteosarcoma

AIMS

An immunohistochemical screen for mouse embryos showed that cell adhesion molecule 1 (CADM1), which is an immunoglobulin superfamily member, was expressed in developing bones. Here, we determined the cell types expressing CADM1 and examined its usefulness in the differential diagnosis of osteosarcoma.

MAIN METHODS

Serial sections of murine developing mandibles were stained with anti-CADM1 antibody, by a coloring substrate reactive to alkaline phosphatase (ALP), a broad osteoblastic marker for preosteoblasts to osteoblasts, and by in situ hybridization for osteopontin (OPN), a marker for mature osteoblasts. CADM1 immunohistochemistry was also performed on human remodeling bones, osteosarcomas and other soft tissue tumors.

KEY FINDINGS

CADM1 immunohistochemistry for the mandible revealed that morphologically identifiable osteoblasts expressed CADM1 on their plasma membranes, but neither osteocytes nor bone lining cells did. At the mandibular margin, not only OPN-positive cells but also OPN-negative, ALP-positive cells were CADM1-positive, whereas inside the mandible, OPN-positive cells were often CADM1-negative. Clear membranous staining was detected in the majority of osteosarcomas (46/57), whereas only 13% (6/46) of the other soft tissue tumors were CADM1-positive (P<0.001).

SIGNIFICANCE

These results indicated that CADM1 was a novel osteoblastic adhesion molecule that is expressed transiently during osteoblastic maturation, and a useful diagnostic marker for osteosarcoma cells.

Evidence for the dysregulated expression of TWIST1, TGFβ1 and SMAD3 in differentiating osteoblasts from primary hip osteoarthritis patients

OBJECTIVE

This study compared human primary osteoblasts derived from hip osteoarthritis (OA) cases against controls (CTLs) to investigate candidate OA disease genes, twist homologue 1 (TWIST1), wingless MMTV integration site family member 5B (WNT5B), transforming growth factor-β (TGFβ1) and SMAD family member 3 (SMAD3), during osteoblast differentiation, relative to calcium apposition and elemental mineral composition.

MATERIALS & METHODS

Primary osteoblast cultures were generated from intertrochanteric trabecular bone samples from five female primary hip OA cases and five age-matched female CTLs. During a 42-day differentiation time-course, alizarin red stains, energy-dispersive X-ray spectroscopy and real-time RT-polymerase chain reaction (PCR) were used to quantify calcium, elemental composition and gene expression, respectively. Data were analysed using linear mixed effects models and Pearson correlation matrices.

RESULTS

Significant differences, correlations and associations were found in OA and CTL osteoblasts between gene and mineral measures. The calcium: phosphorous (Ca:P) ratio was significantly more varied in OA compared to CTL. Calcium apposition, mineral composition as well as TWIST1 and TGFβ1 mRNA expression changed significantly over time. TWIST1 mRNA expression was elevated and correlated with SMAD3 mRNA levels in the OA cohort during the time-course. Associations were observed between tissue non-specific alkaline phosphatase (TNAP), osteocalcin (OCN), TWIST1, TGFβ1, SMAD3 mRNA levels and mineral measures in OA against CTL. Temporal differences between SMAD3 mRNA expression and mineral composition were also found in OA.

CONCLUSIONS

Dysregulated expression of TWIST1, TGFβ1 and SMAD3 mRNA observed in OA bone is reflected in the functionality of the osteoblast when these cells are cultured ex vivo. The results presented here are consistent with at least part of the aetiology of primary hip OA deriving from altered intrinsic properties of the osteoblast.

No association between markers of inflammation and osteoarthritis of the hands and knees

OBJECTIVE

Local inflammation plays a prominent role in osteoarthritis (OA). This could be reflected in the presence of elevated soluble inflammatory markers. We conducted analyses to assess the association of inflammatory markers with radiographic OA of the hands and knees in a large community-based cohort.

METHODS

The Framingham Offspring cohort consists of the adult children of the original cohort and their spouses. In 1998-2001 these subjects provided blood specimens that were tested for 17 markers of systemic inflammation. In 2002-2005 these subjects had radiographs of both knees and hands. Each hand and knee joint was assigned a Kellgren and Lawrence (KL) score (0-4). We used logistic regression with generalized estimating equations and adjustment for age, sex, and body mass index to examine the association between each inflammatory marker and the presence of radiographic OA (ROA = KL grade ≥ 2) in any joint. We also constructed models for hand joints and knee joints alone.

RESULTS

Radiographs and measures of inflammation were done for 1235 subjects (56% women, mean age 65 yrs). Of that group, 729 subjects (59%) had ROA in ≥ 1 hand or knee joint: 179 (14.3%) had knee OA, and 694 (56.2%) had hand OA. There were no significant associations between any marker of inflammation and ROA.

CONCLUSION

In this large sample, in which OA was carefully assessed and multiple markers measured, we found no evidence of an association between any inflammatory marker and the presence of radiographic OA.

Micro-CT and mechanical evaluation of subchondral trabecular bone structure between postmenopausal women with osteoarthritis and osteoporosis

SUMMARY

An inverse relationship between osteoarthritis and osteoporosis has been debated over years. The microstructure of the femoral heads from postmenopausal osteoarthritic and osteoporotic women was evaluated with micro-CT. Significant differences were observed in microstructural parameters between them. Different microstructure might relate to the opposite bone defects in osteoarthritis and osteoporosis.

INTRODUCTION

This study was undertaken to verify the inverse relationship between osteoarthritis (OA) and osteoporosis (OP) by comparing the structural and mechanical indices.

METHODS

Femoral head specimens were obtained from 17 postmenopausal women (OA, n = 8; OP, n = 9) during hip surgery. The microstructural parameters were measured with micro-CT. Mechanical test was performed after bone cube scanning.

RESULTS

Significant difference in bone volume fraction (BV/TV) and trabecular thickness was noted between OA and OP groups. Structure model index decreased in OA, and increased in OP. The higher apparent density (AD) and lower material density (MD) were also shown in OA. Different from OP, positive correlation were noted between connectivity density and mechanical indices in OA. In OA group, BV/TV was associated with Young's modulus and AD, while trabecular number was the only parameter that correlated with MD. However, in OP group, only BV/TV correlated with yield strength, AD, and MD.

CONCLUSIONS

We observed the difference in microstructure between postmenopausal women with OA and OP, which might relate to the opposite bone defects in OA and OP. BV/TV might play an important role in mechanical properties of the subchondral bone in either OA or OP.

Is osteoarthritis a heterogeneous disease that can be stratified into subsets?

Osteoarthritis is a heterogeneous disease characterized by variable clinical features, biochemical/genetic characteristics, and responses to treatments. To optimize palliative effects of current treatments and develop efficacious disease-modifying interventions, treatments may need to be tailored to the individual or a subset of osteoarthritic joints. The purpose of this review is to explore the current literature on the clinical and physiological variability in osteoarthritis and potential for stratifying patients. Several stratifications have been reported, including mechanism of onset, stage of disease progression, involved joints, inflammatory levels, and effusion. Most of these methods revealed two to three unique subsets of osteoarthritis. Osteoarthritic joints may be stratified by an array of variables, some transient and others consistent throughout the disease process. Future research needs to continue to explore stratification techniques since these may be the key to optimizing palliative interventions and developing disease-modifying interventions for subsets within this heterogeneous disease.

ICAM-1 expression in vaginal cells as a potential biomarker for inflammatory response

This study aimed to elucidate the mechanisms that may lead to an efficient strategy to induce a suitable host response of the vaginal mucosa upon exposure to intravaginally delivered exogenous compounds. It was hypothesized that the upregulation of intercellular adhesion molecule (ICAM)-1 gene expression may reflect the inflammatory response evoked by exogenous compounds. Major emphasis was placed on ethylenediamine tetraacetic acid (EDTA) which was added as a synergistic agent to conventional spermicidal agents or anti-HIV drugs. The levels of ICAM-1 mRNA were examined as a surrogate marker for inflammatory response in human vaginal epithelial cells upon exposure to EDTA or interleukin (IL)-1beta (i.e. positive control, 25 mM). The effects of estrogen on EDTA-induced ICAM-1 expression were also evaluated for the estrogen involvement in the inflammatory process of the vaginal mucosa. ICAM-1 expression in human vaginal cells (VK2/E6E7 cells) increased as EDTA concentration added to human vaginal cell lines increased. The effects of estrogen on EDTA-induced ICAM-1 expression in human vaginal epithelial cells were estrogen-concentration dependent; estrogen at lower concentrations (approximately 1-10 nM) did not affect ICAM-1 expression, whereas estrogen at higher concentrations (approximately 100 nM-1 microM) attenuated ICAM-1 expression. The influence of estrogen in ICAM-1 expression suggests the beneficial effects of estrogen on the regulation of vaginal homeostasis. Identification and quantification of specific surrogate markers for the inflammatory response evoked by exogenous compounds and their regulation by estrogen will lead to an efficient strategy against sexually transmitted diseases including AIDS.

An active role for soluble and membrane intercellular adhesion molecule-1 in osteoclast activity in vitro

In osteoclastogenesis, the intercellular adhesion molecule (ICAM)-1 provides a high-affinity adhesion between the osteoblast and the osteoclast precursor, thereby facilitating the interaction between receptor activator nuclear factor kappaB ligand (RANKL) and its receptor RANK. However, the role of soluble ICAM (sICAM) in that process remains obscure. Therefore, the purpose of this study was to determine whether sICAM and ICAM-1 play an active role in the formation and maturation of osteoclasts. Monocytes isolated from healthy donors and cultured alone or with human osteoblast were stimulated with macrophage colony-stimulating factor, sRANKL, ICAM-1 monoclonal antibody (mAb), leucocyte function antigen (LFA)-1 mAb, and/or sICAM to produce mature osteoclasts. Release of TRAP 5b and resorption area were analyzed as markers of osteoclast formation and function, respectively. The effect of ICAM-1 and sICAM stimulation on apoptosis, cathepsin K, alphavbeta3, collagen-1, and on RANKL/osteoprotegerin (OPG)/RANK expression was evaluated. sICAM did not modify the release of TRAP 5b from osteoclast precursors in both mono and co-culture, but induced a significant increase in resorption area in both culture systems, as well as a positive effect on cathepsin K and alphavbeta3 protein expression. Cross-linking ICAM-1 on osteoblast resulted in increased RANKL mRNA and caspase-3 protein expression, decreased collagen-1 mRNA expression, and decreased osteoblast survival. Stimulation of preosteoclast with sICAM produced a significant increase in preosteoclast survival and a decrease in caspase-3 expression. These results indicate that ICAM-1 and sICAM have a dual effect on bone homeostasis, increasing osteoclast activity while lowering osteoblast anabolic activity.

The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder

A key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.

Evidence for two distinct pathways in TNFalpha-induced membrane and soluble forms of ICAM-1 in human osteoblast-like cells isolated from osteoarthritic patients

OBJECTIVE

The present study aimed to investigate the modulation of membrane-bound intercellular adhesion molecule-1 (mICAM-1) and soluble ICAM-1 (sICAM-1) expression by tumor necrosis factor-alpha (TNFalpha) in human osteoarthritic (OA) osteoblasts.

METHODS

Cultured human primary osteoblasts were stimulated with increasing concentrations of human recombinant TNFalpha. Expression of mICAM-1 and sICAM-1 was evaluated by immunocytochemistry, enzyme-linked immunosorbent assay and semi-quantitative reverse transcriptase-polymerase chain reaction. In addition, we investigated the molecular mechanisms underlying ICAM-1 induction by TNFalpha, focusing on the activation of the mitogen-activated protein kinases (MAPKs) and nuclear factor-kappaB (NF-kappaB) pathways.

RESULTS

Our data showed that TNFalpha dose-dependently increased mICAM-1 and sICAM-1 expression at the protein and mRNA levels in OA osteoblasts. The inhibitor of de novo mRNA synthesis, actinomycin D, suppressed TNFalpha-induced mICAM-1 and sICAM-1 expression. Upon examination of the signaling components, we found that TNFalpha was a potent activator of p38, p44/42, p54/46 MAPK, and IkappaBalpha (IkappaBalpha). The chemical inhibitors of p38, p44/42 MAPK, and NF-kappaB blocked TNFalpha-induced mICAM-1 expression but not that of sICAM-1. Transfection experiments revealed that p38 MAPK or IkappaB kinase alpha (IKKalpha) overexpression enhanced TNFalpha-induced mICAM-1 production. Furthermore, osteoblasts treatment with a chemical inhibitor of metalloproteinase-9 (MMP-9) activity, a proteolytic enzyme involved in ICAM-1 cleavage, evoked a significant 25% decrease of TNFalpha-induced sICAM-1 release.

CONCLUSION

Taken together, these findings illustrate the central role played by TNFalpha in the regulation of ICAM-1. We suggest that TNFalpha differentially regulates sICAM-1 and mICAM-1 expression and that sICAM-1 release involves, in part, the proteolytic cleavage of mICAM-1 by MMP-9. The capacity of the MMP-9 inhibitor to prevent sICAM-1 production may be useful for the development of novel therapeutic approaches relevant to OA.

Werner Syndrome as an Example of Inflamm-aging: Possible Therapeutic Opportunities for a Progeroid Syndrome?

Werner syndrome (WS) is a premature aging disorder that is widely used as a model for some aspects of the normal human aging process. Individuals with WS have several of the characteristics of normal aging, such as cataracts, hair graying, and skin aging, but manifest these at an early age. In addition, WS is associated with high levels of inflammatory diseases such as atherosclerosis and type II diabetes. Recent data have indicated that fibroblasts derived from individuals with WS have activated a major molecular pathway involved in inflammation. This observation ties in with the presence of high plasma levels of inflammatory cytokines in individuals with WS. In this paper, the authors discuss the possibility that WS is an example of "inflamm-aging," in that many of the phenotypic manifestations may result from an increased inflammatory state. Moreover, drugs that specifically block this inflammation pathway may be possible candidates for therapeutic intervention in WS.

Involvement of ICAM-1 in bone metabolism: a potential target in the treatment of bone diseases?

Bone diseases such as osteoporosis, osteoarthritis and rheumatoid arthritis (RA) affect a great proportion of individuals, with debilitating consequences in terms of pain and progressive limitation of function. Existing treatment of these pathologies has been unable to alter the natural evolution of the disease and, as such, a clearer understanding of the pathophysiology is necessary in order to generate new treatment alternatives. One therapeutic strategy could involve the targeting of intercellular adhesion molecule-1 (ICAM-1; CD54). In bone, ICAM-1 is expressed at the surface of osteoblasts (Obs) and its counter-receptor, leukocyte function-associated antigen-1 (LFA-1; CD11a), at the surface of osteoclast (Oc) precursors. ICAM-1 blockade between the Ob and the pre-Oc results in an inhibition of Oc recruitment and a modulation of inflammation, which could potentially help in controlling disease activity in bone pathologies. So far, clinical studies on ICAM-1 blockade in bone diseases have been limited to RA. A better understanding of the implication of this adhesion molecule in Ob/Oc interactions and inflammatory mediation in the bone pathological state, however, is needed. As new discoveries on the role of this adhesion molecule are being reported, ICAM-1 could become a potential target for other bone diseases as well.