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Biomedical subjects

A R Poole

Publications and source records attributed to A R Poole.

At least 37 records · Page 2Linked to original sources
PubMed2001

An analysis of 14 molecular markers for monitoring osteoarthritis. Relationship of the markers to clinical end-points.

OBJECTIVE: To investigate whether any of 14 serum and urine molecular markers (MMs) used to monitor osteoarthritis (OA) would be associated with particular clinical end-points. DESIGN: Thirty-nine OA patients were bled and urine collected at five time points: at baseline visit and at visits 1, 3, 6 and 12 months later. Twelve clinical measurements were made and the concentrations of each of 14 MMs were determined. Principal component analysis, stepwise linear regression with backward elimination, and logistic regression were used to determine the correlations between MMs and clinical measures. RESULTS: Principal component analysis was used to reduce the 12 clinical measurements into three independent clinical clusters: baseline clinical assessments, changes in clinical assessments and signal joint measurements. The 14 MMs were similarly reduced to five MM clusters. Each of the three clinical clusters was correlated with a single but different MM cluster. Baseline clinical assessments were correlated with bone markers typified by hydroxylysyl pyridinoline (HP) crosslinks, swelling of the signal joint was correlated with inflammation markers, especially CRP, and the change in clinical assessments over the 1 year evaluation was correlated with TGFbeta1. There was no correlation between any of the skeletal markers and the clinical measures, a situation which draws attention to the need for a direct assessment of cartilage damage in OA to validate the use of cartilage markers. CONCLUSIONS: This study demonstrates statistical methodology for analysis of clinical trials using multiple MMs and clinical end-points. The patient numbers are sufficient to test hypotheses of relationships of single MMs such as CRP, TGFbeta1 and HP to clinical measures, but larger clinical trials are needed to validate hypotheses.

Biomarkers↗
PubMed2001

Type II collagen degradation in articular cartilage fibrillation after anterior cruciate ligament transection in rats.

OBJECTIVE: To investigate the kinetics of early cartilage changes in mechanically induced osteoarthritis (OA) and the association of these changes with damage to the type II collagen network. METHODS: Experimental OA was induced by anterior cruciate ligament transsection in the rat knee joint (ACLT-OA). Animals were sacrificed after 2, 7, 14, 28 and 70 days. Knee joints were evaluated using routine histology and immunohistochemistry for denatured (unwound) type II collagen to detect collagen damage. An antibody recognizing the collagenase cleavage site in type II collagen was used to study the role of collagenase in this process. RESULTS: The first changes of the articular cartilage after anterior cruciate ligament transection occurred in the superficial zone. These changes included loss of superficial chondrocytes, swelling of the remaining chondrocytes and superficial fibrillation. The swelling of the chondrocytes did not result from a change towards the hypertrophic phenotype, since these cells did not stain for type X collagen. A marked increase in denatured type II collagen staining was present in the fibrillated areas. Staining of the collagenase cleavage site showed the same distribution as denatured collagen but was clearly less intense. Collagen damage could never be detected before fibrillation occurred and was not present in non-fibrillated areas. CONCLUSIONS: These results indicate that in this model cartilage degeneration starts at the articular surface and that this degeneration is associated with a localized expression of type II collagen degradation products.

Animals↗
PubMed2001

Composition and structure of articular cartilage: a template for tissue repair.

The authors review the structure and composition of articular cartilage. This tissue is composed of an extensive extracellular matrix synthesized by chondrocytes. It contains different zones with respect to depth from the articular surface and has a regional organization around the chondrocytes. Its composition varies regionally and zonally in its collagen and proteoglycan contents and those of other matrix molecules. There is a macrofibrillar collagen network and a microfilamentous network about which other noncollagenous molecules are organized. Its structure and composition are reflective of its special mechanical properties that primarily reflect its tensile strength (collagens) and compressive stiffness (proteoglycan aggrecan) and cell-matrix interactions (noncollagenous proteins).

Cartilage, Articular↗
PubMed2001

Postnatal expression in hyaline cartilage of constitutively active human collagenase-3 (MMP-13) induces osteoarthritis in mice.

It has been suggested that increased collagenase-3 (MMP-13) activity plays a pivotal role in the pathogenesis of osteoarthritis (OA). We have used tetracycline-regulated transcription in conjunction with a cartilage-specific promoter to target a constitutively active human MMP-13 to the hyaline cartilages and joints of transgenic mice. Postnatal expression of this transgene resulted in pathological changes in articular cartilage of the mouse joints similar to those observed in human OA. These included characteristic erosion of the articular cartilage associated with loss of proteoglycan and excessive cleavage of type II collagen by collagenase, as well as synovial hyperplasia. These results demonstrate that excessive MMP-13 activity can result in articular cartilage degradation and joint pathology of the kind observed in OA, suggesting that excessive activity of this proteinase can lead to this disease.

Animals↗
PubMed2001

Spontaneous air space enlargement in the lungs of mice lacking tissue inhibitor of metalloproteinases-3 (TIMP-3).

Tissue inhibitors of metalloproteinases regulate ECM degradation by matrix metalloproteinases (MMPs). We have developed a mouse line deficient for tissue inhibitor of metalloproteinases-3 (TIMP-3), the only TIMP known to reside within the ECM. Homozygous Timp-3-null animals develop spontaneous air space enlargement in the lung that is evident at 2 weeks after birth and progresses with age of the animal. As early as 13 months of age animals become moribund. Lung function, measured by carbon monoxide uptake, is impaired in aged null animals. Lungs from aged null animals have reduced abundance of collagen, enhanced degradation of collagen in the peribronchiolar space, and disorganization of collagen fibrils in the alveolar interstitium, but no increase in inflammatory cell infiltration or evidence of fibrosis in comparison with controls. Using in situ zymography, we show that lungs from aged null animals have heightened MMP activity over wild-type and heterozygotic animals. Finally, TIMP-3-null fibroblast cultures demonstrate enhanced destruction of ECM molecules in vitro. We propose that the deletion of TIMP-3 results in a shift of the TIMP/MMP balance in the lung to favor ECM degradation, culminating in incapacitating illness and a shorter life span.

Air↗
PubMed2001

The balance between collagen synthesis and degradation in diffuse lung disease.

Diffuse interstitial lung disease (DLD) is characterised by varying degrees of inflammation and fibrosis that result in derangement of the gas-exchanging units of the lung. A hallmark of these diseases is the abnormal deposition of collagen, which is a prime determinant of clinical course. This review considers the current information concerning collagen turnover in diffuse fibrotic lung disease. Considerable experimental evidence implicates both increased collagen production and reduced degradation in these diseases. Reduced degradation may result from both reduced production of collagenases and increased inhibition by tissue inhibitors. The known effects upon collagen turnover of novel therapeutic agents for pulmonary fibrosis (pirfenidone and interferon gamma) are discussed.

Animals↗
PubMed2000

Osteoarthritis: new insights. Part 1: the disease and its risk factors.

Osteoarthritis is the most common form of arthritis, affecting millions of people in the United States. It is a complex disease whose etiology bridges biomechanics and biochemistry. Evidence is growing for the role of systemic factors (such as genetics, dietary intake, estrogen use, and bone density) and of local biomechanical factors (such as muscle weakness, obesity, and joint laxity). These risk factors are particularly important in weight-bearing joints, and modifying them may present opportunities for prevention of osteoarthritis-related pain and disability. Major advances in management to reduce pain and disability are yielding a panoply of available treatments ranging from nutriceuticals to chondrocyte transplantation, new oral anti-inflammatory medications, and health education. This article is part 1 of a two-part summary of a National Institutes of Health conference. The conference brought together experts on osteoarthritis from diverse backgrounds and provided a multidisciplinary and comprehensive summary of recent advances in the prevention of osteoarthritis onset, progression, and disability. Part 1 focuses on a new understanding of what osteoarthritis is and on risk factors that predispose to disease occurrence. It concludes with a discussion of the impact of osteoarthritis on disability.

Age Distribution↗
PubMed2000

Selective assembly and remodelling of collagens II and IX associated with expression of the chondrocyte hypertrophic phenotype.

The assembly and resorption of the extracellular matrix in the physis of the growth plate are poorly understood. By examining isolated fetal growth plate chondrocytes in culture and using immunochemical methods we show that type II collagen, proteoglycan aggrecan, and type IX collagen are assembled into a matrix that is initially enriched in type II collagen over proteoglycan and type IX collagen. When compared to the content of the COL2 domain in the alpha(1)(IX) chain it is evident that the majority ( 90%) of type IX molecules lack the NC4 domain unlike in articular cartilage. During matrix assembly the molar ratio of type II/COL2 of alpha(1)(IX) varied from 25:1 to 2.5:1. Following expression of the hypertrophic phenotype (initiation of type X collagen synthesis) there are parallel changes in both collagen and proteoglycan contents (inversely related to collagenase cleavage of type II collagen). The NC4 domain is then selectively, rapidly and irreversibly removed as mineralization is initiated, leaving the alpha(1)(IX) chain COL2 domain. Subsequently as mineralization progresses type II and type IX collagen (COL2 domain), but not the proteoglycan aggrecan, are resorbed coincident with a markedly increased cleavage of type II collagen by collagenase as mineral is deposited in the matrix. This study, therefore reveals a carefully orchestrated series of events in matrix assembly and resorption that prepares the extracellular matrix for mineralization.

Animals↗
PubMed2000

Comparison of the degradation of type II collagen and proteoglycan in nasal and articular cartilages induced by interleukin-1 and the selective inhibition of type II collagen cleavage by collagenase.

OBJECTIVE: To compare interleukin-1alpha (IL-1alpha)-induced degradation of nasal and articular cartilages in terms of proteoglycan loss and type II collagen cleavage, denaturation, and release; to examine the temporal relationship of these changes; and to investigate the effects of an inhibitor of collagenase 2 and collagenase 3 on these catabolic processes. METHODS: Discs of mature bovine nasal and articular cartilages were cultured with or without human IL-1alpha (5 ng/ml) with or without RS102,481, a selective synthetic inhibitor of collagenase 2 and collagenase 3 (matrix metalloproteinase 8 [MMP-8] and MMP-13, respectively) but not of collagenase 1 (MMP-1). Immunoassays were used to measure collagenase-generated type II collagen cleavage neoepitope (antibody COL2-3/4C(short)) and denaturation (antibody COL2-3/4m), as well as total type II collagen content (antibody COL2-3/4m) in articular cartilage and culture media. A colorimetric assay was used to measure total proteoglycan concentration (principally of aggrecan) as sulfated glycosaminoglycans (sGAG). RESULTS: IL-1alpha initially induced a decrease in tissue proteoglycan content in nasal cartilage. A progressive loss of proteoglycan was noted during culture in articular cartilages, irrespective of the presence of IL-1alpha. In both cartilages, proteoglycan loss was followed by IL-1alpha-induced cleavage of type II collagen by collagenase, which was often reflected by increased denaturation. The inhibitor RS102,481 had no clear effect on the reduction in proteoglycan content (measured by sGAG) and collagen denaturation in either cartilage, but at 10 nM it inhibited the enhanced cleavage of type II collagen, partially in nasal cartilage and completely in articular cartilage. CONCLUSION: IL-1alpha-induced cleavage and denaturation of type II collagen is observed in both hyaline cartilages and is secondary to proteoglycan loss. It probably involves different collagenases, since there is no evidence of a rate-limiting role for collagenase 1 in articular cartilage, unlike the case for nasal cartilage. Inhibitors of this kind may be of value in the treatment of cartilage damage in arthritis. Also, the ability to detect the release of type II collagen collagenase-generated fragments from degraded cartilage offers the potential to monitor cartilage collagen damage and its control in vivo.

Animals↗
PubMed2000

Selective enhancement of collagenase-mediated cleavage of resident type II collagen in cultured osteoarthritic cartilage and arrest with a synthetic inhibitor that spares collagenase 1 (matrix metalloproteinase 1).

OBJECTIVE: To examine whether type II collagen cleavage by collagenase and loss of proteoglycan are excessive in human osteoarthritic (OA) articular cartilage compared with nonarthritic articular cartilage, and whether this can be inhibited by a selective synthetic inhibitor that spares collagenase 1 (matrix metalloproteinase 1 [MMP-1]). METHODS: Articular cartilage samples were obtained during surgery from 11 patients with OA and at autopsy from 5 adults without arthritis. The articular cartilage samples were cultured in serum-free medium. A collagenase-generated neoepitope, which reflects cleavage of type II collagen, and proteoglycan glycosaminoglycan (GAG), which predominantly reflects aggrecan release, were assayed in culture media. In addition, cultures were performed using either of 2 synthetic MMP inhibitors, both of which inhibited collagenase 2 (MMP-8) and collagenase 3 (MMP-13), but one of which spared collagenase 1. Cultures were also biolabeled with 3H-proline in the presence and absence of these inhibitors to measure collagen synthesis (as tritiated hydroxyproline) and incorporation in articular cartilage. RESULTS: As a group, cleavage of type II collagen by collagenase was significantly increased in OA cartilage samples. In contrast, proteoglycan (GAG) release was not increased. This release of a collagenase-generated epitope was inhibited by both MMP inhibitors in 2 of 5 nonarthritic samples and in 9 of 11 OA cartilage samples. The inhibitor that spared collagenase 1 was generally more effective and inhibited release from 4 of 5 nonarthritic cartilage samples and the same OA cartilage samples. Group analyses revealed that the inhibition of collagenase neoepitope release by both inhibitors was significant in the OA patient cartilage, but not in the nonarthritic cartilage. Proteoglycan loss was unaffected by either inhibitor. Newly synthesized collagen (predominantly, type II) exhibited increased incorporation in OA cartilage, but only in the presence of the inhibitor that arrested collagenase 1 activity. CONCLUSION: These results further indicate that the digestion of type II collagen by collagenase is selectively increased in OA cartilage, and that this can be inhibited in the majority of cases by a synthetic inhibitor that can inhibit collagenases 2 and 3, but not collagenase 1. The results also suggest that in OA, newly synthesized collagen is digested, but in a different manner than that of resident molecules. Proteoglycan release was not increased in OA cartilage and was unaffected by these inhibitors. Inhibitors of this kind may be of value in preventing damage to type II collagen in human arthritic articular cartilage.

Adult↗
PubMed2000

Alterations in cartilage type-II procollagen and aggrecan contents in synovial fluid in equine osteochondrosis.

The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C-propeptide of cartilage type-II procollagen, which is released following the synthesis of this molecule, to analyse synovial fluids from equine tarsocrural joints with and without osteochondrosis. In young horses with osteochondrosis, there was a significant increase of C-propeptide of type-II procollagen accompanied by a decrease in the 846 and keratan sulfate epitopes. The results identify differential alterations in aggrecan and type-II collagen turnover in the cartilage matrix in young animals with osteochondrosis that may contribute to the pathological degeneration of articular cartilage in this disease.

Aggrecans↗
PubMed2000

Isolation and characteristics of autoreactive T cells specific to aggrecan G1 domain from rheumatoid arthritis patients.

Our previous work showed that the cartilage proteoglycan aggrecan could induce an erosive polyarthritis and spondylitis in BALB/c mice and the G1 globular domain of the aggrecan (G1) contained the arthritogenic region. To elucidate whether autoreactive T cells to G1 are expressed in rheumatoid arthritis patients, we analyzed the frequency of human G1-specific T cells in the peripheral blood of five rheumatoid arthritis patients and tried to establish G1-reactive T cell lines from these rheumatoid arthritis patients. The results showed that the G1-specific T cells in PBL were detectable at the range of 4.97 +/- 0.5 x 10(-6) in peripheral blood lymphocytes. We have also generated 15 G1-specific T lymphocyte lines from these patients with a standard split-well method. All these cells expressed fine specificity to human recombinant G1, but not to unrelated antigen. All the 15 lines expressed a pan-T cell marker and 13 of them selectively used the alphabeta T cell receptor. Two of them used gammadelta T cell receptor. The 13 of these T cell lines was CD4 positive. One line expressed CD8. One line expressed both CD4 and CD8. Moreover, 14 out of 15 lines expressed the Th-1 cytokine profile, characterized by interferon-gamma positivity and IL-4 negativity. No Th-2 type cell line was generated. These data provide strong evidence in favor of the presence of autoreactive T cells in the rheumatoid arthritis patients. What is the mechanism(s) that these autoreactive T cells attack self-target and whether these G1-specific, Th-1 type T cell lines can induce arthritis in immune deficiency mice are currently under investigation.

Adult↗
PubMed2000

An analysis of 14 molecular markers for monitoring osteoarthritis: segregation of the markers into clusters and distinguishing osteoarthritis at baseline.

OBJECTIVE: To investigate the relationships between serum and urinary molecular markers (MM) used to monitor osteoarthritis. DESIGN: Forty osteoarthritis patients had blood and urine collected at baseline and 1, 3, 6 and 12 months later. Specimens from 20 controls were obtained twice at a one month interval. The concentration of 14 different markers was determined at each time point and the data were analyzed by statistical methodology. RESULTS: The markers could be divided by the method of principal components analysis into five clusters of related markers: inflammation markers (C-reactive protein, tumor necrosis receptor type I and tumor necrosis receptor type II, interleukin 6, eosinophilic cationic protein), bone markers (bone sialoprotein, hydroxylysyl pyridinoline, lysyl pyridinoline), putative markers of cartilage anabolism (carboxypropeptide of type II procollagen, hyaluronan, epitope 846) and catabolism (keratan sulfate, cartilage oligomeric matrix protein), and transforming growth factor beta. Three markers (tumor necrosis factor receptor II, cartilage oligomeric matrix protein and epitope 846) from independent clusters discriminated osteoarthritis patients from controls. Inflammation was not a confounding factor in measurement, but a recognizable distinguishing factor in osteoarthritis. CONCLUSIONS: The markers separated into rational groups on the basis of their covariance, a finding with independent biochemical support. The covariance of markers from the same cluster suggests the use of a representative marker from the cluster to reflect changes in osteoarthritis. If multiple markers are being measured within a single cluster, then the use of a weighted cluster 'factor' may be preferable to the separate use of individual markers.

Amino Acids↗
PubMed1999

An introduction to the pathophysiology of osteoarthritis.

Osteoarthritis involves the degeneration of articular cartilage together with changes in subchondral bone and limited intra-articular inflammation. In this chapter these changes are reviewed at the tissue, cell and molecular levels to reveal the complexity of a process which involves multiple changes in joint structure and turnover.

Animals↗
PubMed1999

MT1-MMP-deficient mice develop dwarfism, osteopenia, arthritis, and connective tissue disease due to inadequate collagen turnover.

MT1-MMP is a membrane-bound matrix metalloproteinase (MT-MMP) capable of mediating pericellular proteolysis of extracellular matrix components. MT1-MMP is therefore thought to be an important molecular tool for cellular remodeling of the surrounding matrix. To establish the biological role of this membrane proteinase we generated MT1-MMP-deficient mice by gene targeting. MT1-MMP deficiency causes craniofacial dysmorphism, arthritis, osteopenia, dwarfism, and fibrosis of soft tissues due to ablation of a collagenolytic activity that is essential for modeling of skeletal and extraskeletal connective tissues. Our findings demonstrate the pivotal function of MT1-MMP in connective tissue metabolism, and illustrate that modeling of the soft connective tissue matrix by resident cells is essential for the development and maintenance of the hard tissues of the skeleton.

Animals↗
PubMed1999

Secretory leukocyte protease inhibitor suppresses the inflammation and joint damage of bacterial cell wall-induced arthritis.

Disruption of the balance between proteases and protease inhibitors is often associated with pathologic tissue destruction. To explore the therapeutic potential of secretory leukocyte protease inhibitor (SLPI) in erosive joint diseases, we cloned, sequenced, and expressed active rat SLPI, which shares the protease-reactive site found in human SLPI. In a rat streptococcal cell wall (SCW)-induced model of inflammatory erosive polyarthritis, endogenous SLPI was unexpectedly upregulated at both mRNA and protein levels in inflamed joint tissues. Systemic delivery of purified recombinant rat SLPI inhibited joint inflammation and cartilage and bone destruction. Inflammatory pathways as reflected by circulating tumor necrosis factor alpha and nuclear factor kappaB activation and cartilage resorption detected by circulating levels of type II collagen collagenase-generated cleavage products were all diminished by SLPI treatment in acute and chronic arthritis, indicating that the action of SLPI may extend beyond inhibition of serine proteases.

Amino Acid Sequence↗