Calcium Pyrophosphate Dihydrate Crystals Research Articles

TLR2 Signaling in Chondrocytes Drives Calcium Pyrophosphate Dihydrate and Monosodium Urate Crystal-Induced Nitric Oxide Generation

Microcrystals of calcium pyrophosphate dihydrate (CPPD) and monosodium urate (MSU) deposited in synovium and articular cartilage initiate joint inflammation and cartilage degradation in large part by binding and directly activating resident cells. TLRs trigger innate host defense responses to infectious pathogens, and the expression of certain TLRs by synovial fibroblasts has revealed the potential for innate immune responses to be triggered by mesenchymally derived resident cells in the joint. In this study we tested the hypothesis that chondrocytes also express TLRs and that one or more TLRs centrally mediate chondrocyte responsiveness to CPPD and MSU crystals in vitro. We detected TLR2 expression in normal articular chondrocytes and up-regulation of TLR2 in osteoarthritic cartilage chondrocytes in situ. We demonstrated that transient transfection of TLR2 signaling-negative regulator Toll-interacting protein or treatment with TLR2-blocking Ab suppressed CPPD and MSU crystal-induced chondrocyte release of NO, an inflammatory mediator that promotes cartilage degeneration. Conversely, gain-of-function of TLR2 in normal chondrocytes via transfection was associated with increased CPPD and MSU crystal-induced NO release. Canonical TLR signaling by parallel pathways involving MyD88, IL-1R-associated kinase 1, TNF receptor-associated factor 6, and IkappaB kinase and Rac1, PI3K, and Akt critically mediated NO release in chondrocytes stimulated by both CPPD and MSU crystals. We conclude that CPPD and MSU crystals critically use TLR2-mediated signaling in chondrocytes to trigger NO generation. Our results indicate the potential for innate immunity at the level of the articular chondrocyte to directly contribute to inflammatory and degenerative tissue reactions associated with both gout and pseudogout.

Crystal arthropathy of the lumbar spine

There have been very few reports in the literature of gout and pseudogout of the spine. We describe six patients who presented with acute sciatica attributable to spinal stenosis with cyst formation in the facet joints. Cytopathological studies confirmed the diagnosis of crystal arthropathy in each case. Specific formation of a synovial cyst was identified pre-operatively by MRI in five patients. In the sixth, the diagnosis was made incidentally during decompressive surgery. Surgical decompression alone was undertaken in four patients. In one with an associated degenerative spondylolisthesis, an additional intertransverse fusion was performed. Another patient had previously undergone a spinal fusion adjacent to the involved spinal segment, and spinal stabilisation was undertaken as well as a decompression. In addition to standard histological examination material was sent for examination under polarised light which revealed deposition of urate or calcium pyrophosphate dihydrate crystals in all cases. It is not possible to diagnose gout and pseudogout of the spine by standard examination of a fixed specimen. However, examining dry specimens under polarised light suggests that crystal arthropathy is a significant aetiological factor in the development of symptomatic spinal stenosis associated with cyst formation in a facet joint.

A case of chronic calcium pyrophosphate dihydrate crystal disease (tophaceous pseudogout) in the temporomandibular joint

Pseudogout is a rare joint disease which is characterized by the presence of calcium pyrophosphate dihydrate crystals in the intraarticular and periarticular tissue. The crystals tend to attach to fibrocartilage tissue. Pseudogout principally affects the knee and wrist joints. Involvement of the temporomandibular joint (TMJ) is very rare. There have been <20 cases reported world-wide. Both acute and chronic manifestations have been described. We present here an unusual case that necessitated a high condylectomy.

Calcium pyrophosphate dihydrate crystal deposition disease of the temporomandibular joint

A case of a 74-year-old woman with calcium pyrophosphate dihydrate crystal deposition disease of the temporomandibular joint (TMJ) is presented. This disease rarely involves the TMJ and is not usually considered in the differential diagnosis of TMJ disorders. To our knowledge, only 23 cases have been reported in the literature and only four without any destructive changes of the condyle as in the present case.

Improvement of Acute Pseudogout Attacks after Parathyroidectomy in Patients with Pseudogout and Primary Hyperparathyroidism-Two Cases Report and Review of Literature

Pseudogout is a clinical entity characterized by acute arthritis in one or more joints associated with the presence of calcium pyrophosphate dihydrate (CPPD) crystals in the synovial fluid of the affect joints. It is also known as a biochemical entity associated with primary hyperparathyroidism and it may offer a useful clue to screen the disease. Patients with long standing hypercalcemia related to hyperparathyroidism have a high incidence of CPPD crystal deposition in the articular cartilage which is so called chondrocalcinosis. In patients of CPPD deposition disease with primary hyperparathyroidism, relative hypocalcemia after parathyroidectomy could provide stimulus for crystal shedding into synovial fluid, which may precipitate acute attacks of pseudogout. Thus, trying calcium supplement after parathyroid surgery may be a good and reasonable consideration to prevent the postoperative complication. Here, we illustrate two female patients of pseudogout related arthritis with primary hyperparathyroidism, and, both of them have single-gland disease who go on parathyroidectomy experienced much improvement in pseudogout attacks after surgical interventions.

Foraminal deposition of calcium pyrophosphate dihydrate crystals in the thoracic spine: possible relationship with disc herniation and implications for surgical planning

The authors report two cases of nodular calcium pyrophosphate dihydrate (CPPD) crystal deposition close to the thoracic neural foramen, which caused chronic radiculopathy. Preoperatively, the lesions were interpreted as calcified disc herniations. Both patients underwent surgery in which an extended transfacet pedicle-sparing approach was used. Incision of the posterior longitudinal ligament released soft degenerated material. In both cases, histological examination showed abundant degenerative debris along with CPPD crystals. Spinal CPPD deposition is a comparatively rare disease that almost invariably involves the posterior aspect of the spinal canal, typically the ligamentum flavum. The exceptional foraminal location of the lesions reported here, combined with the surgical findings, indicated that the CPPD crystals were deposited on a laterally herniated disc fragment. A distinctive feature in both cases was the soft consistency of the resected tissue. The consistency of the disc material and the location of the lesion in the axial plane (that is, median compared with lateral) are key factors in determining the optimal surgical approach to thoracic disc herniations. In describing consistency, terms such as "calcified" and "hard" have been used interchangeably in the literature. In the cases reported here, what appeared on computerized tomography and magnetic resonance imaging studies to be densely calcified lesions were shown intraoperatively to be soft herniations. The authors' experience underscores that not all densely calcified herniated discs are hard. Although detection of this discrepancy would have left surgical planning for the lateral disc herniations unchanged, it could have altered planning for centrally or centrolaterally located disc herniations.

Role of calcium-containing crystals in osteoarthritis

The deposition of calcium-containing crystals in articular tissues is probably an underrecognized event. Clinical observations indicate that exaggerated and uniquely distributed cartilage degeneration is associated with these deposits. Perhaps the most compelling argument favoring a role for crystals in causing osteoarthritis stems from their in vitro effects on articular tissues. In this review, we will highlight some of the recent findings that further reinforce the thesis that basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPPD) crystals can cause the degeneration of articular tissues in 2 separate pathways. In the "Direct" pathway, crystals directly induce fibro-blast-like synoviocytes to proliferate and produce metalloproteinases and prostaglandins. The other "Paracrine Pathway" involves the interaction between crystals and macrophages/monocytes which leads to synthesis and release of cytokines which can reinforce the action of crystals on synoviocytes and/or induce chondrocytes to secrete enzymes and which eventually cause the degeneration of articular tissues.

副甲状腺摘出後に発症した偽痛風例

We reported a patient with pseudogout associated with parathyroidectomy. A 68-year-old woman, diagnosed with primary hyperparathyroidism, presented with serum concentrations of ionized calcium. Patients with hypercalcemia have a high incidence of calcium pyrophosphate dihydrate crystal deposition into joints. Rapid drops in serum calcium levels can cause shedding of these crystals into synovial fluid which may precipitate acute attacks of pseudogout. Furthermore, the patient has diabetes mellitus. Diabetes mellitus inhibits insorption of magnesium which may cause high incidence of calcium pyrophosphate dihydrate crystal deposition into joints, too. It has been well established that acute attacks of pseudogout may be precipitated by parathyroidectomy and/or diabetes mellitus.

Condrocalcinose articular familiar

Condrocalcinose articular familiar é uma condição clínica caracterizada pela deposição de cristais de pirofosfato de cálcio no líquido sinovial e cartilagens articulares levando à artrite. Descrevemos três membros de uma família com condrocalcinose cujo quadro clínico era caracterizado por artrite intermitente em dois e artrite crônica lembrando artrite reumatóide em um. A avaliação radiológica mostrou calcificações em cartilagens de diversas articulações, particularmente de joelhos. A utilização de colchicina foi suficiente para prevenir as crises de artrite em dois pacientes e o paciente com a forma crônica necessitou uso contínuo de antiinflamatórios não-hormonais. Embora aparentemente rara no Brasil, não afastamos a possibilidade desse dado estar subestimado e sugerimos que seja realizada uma avaliação radiológica articular dos familiares de todo paciente com diagnóstico de condrocalcinose esporádica.

How crystals damage tissue.

Basic calcium phosphate, calcium pyrophosphate dihydrate, and monosodium urate crystals are the most common types of crystals associated with human disease. Although there is a well-established association between these crystals and various forms of joint disease, recent evidence points to an association of basic calcium phosphate crystals with breast cancer and atherosclerosis. Crystal-induced tissue damage is affected by degradative proteases, cytokines, chemokines, and prostanoids produced by cells stimulated by crystals. In the case of basic calcium phosphate and calcium pyrophosphate dihydrate crystals, these responses are augmented by the cellular proliferation that results from their induction of mitogenesis. The understanding of the molecular mechanisms involved in generating these pathologic effects has been significantly advanced in recent years. Such advances are essential to the ongoing search for more effective therapies for crystal-associated diseases.

Calcium pyrophosphate dihydrate and basic calcium phosphate crystal-induced arthropathies: update on pathogenesis, clinical features, and therapy.

Calcium-containing crystals are the most common class for the osteoarthritic joint. They are responsible for acute periarthritis and destructive arthropathies, and for tissue deposits mimicking tumor-like masses. These crystals encompassed mainly calcium pyrophosphate dihydrate and basic calcium phosphate crystals, with the latter being related to hydroxyapatite, carbonate-substituted apatite, and octacalcium phosphate. Calcification deposit mechanisms will be reviewed with respect to extracellular inorganic pyrophosphate dysregulation mainly caused by modulation of specific membrane channel disorders. Genetic defects have been extensively studied and identified mutation of specific genes such as ANKH and COL. Pathogenesis of crystal-induced inflammation is related to synovial tissue and direct cartilage activation. Besides classical knee or wrist pseudogout attacks or Milwaukee shoulder arthropathies, clinicians should be aware of other specific common presentations, such as erosive calcifications, spinal cord compression by intraspinal masses, ligamentum flavum calcification, or atypical calcified tophus. Promising clinical results for preventing calcium crystal deposits and cartilage degradation are lacking. Practical imaging tools are needed to monitor reduction of calcification of fibrocartilage and articular cartilage as markers of drug efficacy.

Calcification in calcium pyrophosphate dihydrate (CPPD) crystalline deposits in the knee: anatomic, radiographic, MR imaging, and histologic study in cadavers.

To demonstrate and determine the frequency and location of calcification within cadaveric knees with or without calcification typical of calcium pyrophosphate dihydrate (CPPD), utilizing histologic, radiographic and MR imaging techniques. Ten cadaveric knees of elderly individuals that demonstrated no radiographic evidence of prior surgery or trauma were studied with MR imaging and subsequently sectioned in planes corresponding to those obtained with MR imaging. The slices were imaged with high-resolution radiography. Two musculoskeletal radiologists correlated the anatomic, MR and radiographic findings. Three of the knees, which did not demonstrate calcifications, were utilized as controls. Histologic sections were obtained from four knees that contained calcifications and from the three controls, and analyzed with special histologic stains that demonstrate phosphorus and calcium. Radiographic imaging and histologic analysis demonstrated widespread CPPD crystal deposition in four of the 10 knee specimens (40%). MR imaging demonstrated some calcifications only within the articular cartilage of the femoral condyles in three of the four (75%) specimens that had CPPD deposits. In all four specimens radiographs and histologic analysis were more sensitive than MR imaging. Histologic analysis demonstrated no evidence of CPPD crystals in the control specimens. MR imaging is insensitive to the presence of CPPD deposits in the knee, even when such deposits are widespread. Our study suggests that the sensitivity of MR imaging was significantly better in detecting CPPD deposits in the hyaline cartilage of the femoral condyles when compared with other internal structures, even when such structures contained a higher amount of calcification.

In vitro models of calcium crystal formation.

Calcium pyrophosphate dihydrate crystals are common components of synovial fluids from degenerated joints and often accompany unusually severe cartilage destruction. Progress in understanding why and how calcium pyrophosphate dihydrate crystals form in articular cartilage has been hampered by the scarcity of good models in which to study this phenomenon. In this review, the author discusses various models of calcium pyrophosphate dihydrate crystal formation from early work with solutions and gels to more recent models using cells, tissues, and cell fractions. Each of these systems has advantages and disadvantages. Current models of calcium pyrophosphate dihydrate crystal formation are less than ideal for studying the major factors involved in calcium pyrophosphate dihydrate crystal formation. Borrowing from the transplantation literature, solid matrices that support cell growth and allow for easy manipulation of matrix components hold some promise for better models in the future.

Modulation of chondrocyte production of extracellular inorganic pyrophosphate

Extracellular inorganic pyrophosphate (ePPi) both inhibits and promotes different forms of pathologic mineralization. Basic calcium phosphate (BCP) deposition results from depressed levels of ePPi while excess levels of ePPi leads to calcium pyrophosphate dihydrate crystal deposition (CPPD) disease. These crystals are also often identified in patients with osteoarthritis, the most prevalent form of arthritis causing significant morbidity. The two primary hypotheses for generation of ePPi, export of inorganic pyrophosphate through the multipass transmembrane protein ANK and generation of ePPi by ectoenzyme activity, continue to be supported and better understood through animal models and study of families with CPPD deposition disease. As the pathophysiology of crystal formation in both articular cartilage and synovial fluid is better understood, the opportunity for prevention and treatment of pathologic mineralization increases. In particular, a more complex understanding of the ank gene, ectoenzyme PC-1, and the transglutaminase enzyme family may eventually translate into therapeutic application for both BCP deposition and CPPD deposition disease.

Calcium pyrophosphate dihydrate-crystal induced arthropathy

Calcium pyrophosphate dihydrate (CPPD) crystal induced arthropathy (CPPD-CA; systemic articular chondrocalcinosis) characterized by deposition of CPPD-crystals in fibro- and hyaline cartilage, joint capsule and periarticular tissues is associated with a variable clinical spectrum of inflammatory degenerative and occasionally destructive joint and vertebral manifestations including neurologic complications and rarely tophaceous-tumoral tissue calcifications. Microcrystal formation in the extracellular matrix of cartilage and tendons is based on genetic and acquired dysregulation of chondrocyte pyrophosphate metabolism and presumably linked to gene mutants on the short arm of chromosome-5 (gene locus 5p15.1 and ANKH gene). Idiopathic disease occurs rarely in hereditary-familial and frequently in sporadic manifestation with increasing prevalence due to aging; a secondary form is significantly related to endocrine and metabolic disorders (as to hyperparathyroidism, hemochromatosis etc.). The impact of the clinical syndrome in practice is important in differential diagnosis of age related conditions like acute mono- or oligoarthritis, systemic osteoarthritis and polymyalgia rheumatica. Actual treatment ignores established prevention of systemic cartilage calcification and is oriented to symptomatic relief.

Liquide synovial normal et pathologique

Synovial fluid analysis is a very important diagnosis step in rheumatology. Cell count allows to differenciate inflammatory arthritis, in which cell count exceeds 2000 cells/mm 3, from non inflammatory arthropathy, in which cell count is less than 1000 cells/mm 3. Bacteriological studies must be performed on an emergency basis before antibiotic administration, and must include direct examination and culture, which allow the diagnosis of septic arthritis to be made and the choice of antibacterials. Demonstration of crystals in synovial fluid is a rapid and unexpensive way to diagnose microcrystalline arthritis. Synovial fluid must be examined under normal and polarized light. Equipment of the polarizing light microscope with a compensator and a rotating stage increases its diagnosis performances. Monosodium urate crystals are negatively birefringent, whereas calcium pyrophosphate dihydrate crystals are positively birefringent. Other crystals (cholesterol, oxalate, corticosteroids….) can also be identified in synovial fluid. Various artefacts must be avoided including anticoagulant crystals and synovial fluid must be anticoagulated with sodium heparin or citrate.

Transglutaminase contributes to CPPD crystal formation in osteoarthritis.

Calcium pyrophosphate dihydrate (CPPD) crystals are common components of osteoarthritic joints and correlate with a poor prognosis. Transglutaminase (Tgase) enzymes have been implicated in pathologic mineralization in cartilage; yet, definitive studies linking Tgase activity to CPPD crystal formation in osteoarthritic articular cartilage are lacking. We measured in-vivo Tgase activity in osteoarthritic and normal human cartilage, and explored the effect of Tgase inhibitors on CPPD crystal formation by normal chondrocytes. Osteoarthritic articular cartilage from was obtained from specimens discarded at the time of knee replacement surgery. Normal adult cartilage samples from a tissue bank were used as controls. Tgase-specific isopeptide (epsilon-(gamma-glutamyl) lysine) bonds were measured in cartilage extracts by HPLC. Tgase-specific crosslinks were localized in osteoarthritic cartilage by immunohistochemistry. The effect of Tgase inhibition was determined in an in-vitro model of CPPD crystal formation. Tgase-specific crosslink levels were 1.55 +/- 0.3 picomoles/ng protein in normal human adult articular cartilage and 4.74 +/- 0.7 picomoles/ng protein in osteoarthritic human cartilage (p less than 0.001). Immunostaining confirmed the presence of Tgase crosslinks in the pericellular matrix of chondrocytes at potential sites of CPPD crystal formation. Tgase inhibitors suppressed CPPD crystal formation by porcine chondrocytes. These findings support a role for Tgase in CPPD crystal formation in aging or degenerated cartilage.

The priming action of tumour necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) on neutrophils activated by inflammatory microcrystals.

We studied the effects of TNF-alpha or GM-CSF on the production of reactive oxygen species (as measured by chemiluminescence) and degranulation responses of neutrophils to opsonized inflammatory microcrystals. TNF-alpha in the 10-2000 pM or GM-CSF in the 2-200 pM concentration range caused the concentration-dependent amplification of neutrophil chemiluminescence responses to both calcium pyrophosphate dihydrate (CPPD) and monosodium urate monohydrate (MSUM) crystals. Degranulation responses, as measured by the extracellular release of the granule enzymes myeloperoxidase or lysozyme, were amplified by approximately 50-100% for both MSUM or CPPD crystal-induced neutrophil activation when cells were pretreated with TNF-alpha at 2000 pM or GM-CSF at 75 pM.

Calcium pyrophosphate dihydrate crystal associated induction of neutrophil activation and repression of TNF-α-induced apoptosis is mediated by the p38 MAP kinase

The role of p38 mitogen-activated protein (MAP) kinase in the activation of human neutrophils and repression of TNF-α-induced apoptosis in response to plasma opsonized crystals of calcium pyrophosphate dihydrate (CPPD) was investigated. We monitored the endogenous phosphotransferase activity of p38 kinase in neutrophils stimulated with CPPD crystals (25 mg/ml) alone or in the presence of TNF-α (10 ng/ml), and with TNF-α alone. CPPD crystals induced a 2-fold activation of p38 kinase activity over the basal activity that was observed in untreated neutrophils. Furthermore, CPPD crystals repressed the TNF-α associated 6-fold induction of p38 kinase phosphotransferase activity to levels associated with CPPD crystal incubation alone in a PD98059 (20 ng/ml) and Wortmannin (100 nM) sensitive manner. Inhibition of CPPD crystal-induced activation of the neutrophil inflammatory response as measured by chemiluminescence, superoxide anion generation and degranulation as determined by myeloperoxidase and lysozyme release was observed in the presence of the specific p38 MAP kinase inhibitor SB203580 (5 μM). CPPD crystal associated repression of TNF-α-induced activation of neutrophil apoptosis as determined by DNA fragmentation correlated with the CPPD crystal mediated inhibition of p38 kinase activity, probably through crystal inhibition of caspase 3. Together, our results indicate that the CPPD crystal associated inflammatory response is regulated through the activation of p38 kinase to sub-apoptotic levels, and that the repression of the TNF-α-induced apoptosis program in neutrophils is mediated via the repression of caspase 3 mediated apoptosis-associated p38 kinase activity.

Molecular Dynamics Simulation of Crystal-Induced Membranolysis

Calcium pyrophosphate dihydrate (CPPD) crystals occur frequently in noninflammatory osteoarthritic joints; however, they can be phlogistic and membranolytic, causing acute pseudogout attack. So far, the molecular mechanism of crystal-induced membranolysis is still unclear. In this study, using the method of Chemistry at Harvard Macromolecular Mechanics (CHARMM) molecular dynamics, we show that the interactions between the surface of CPPD crystal and the extracellular layer of the hydrated dimyristoyl phosphatidylcholine (DMPC) phospholipid bilayer may lead to decoupling of the external layer from the intracellular side of the membrane. As a result, a local thinning of the layer on the intracellular side of the membrane occurs, which favors water penetration, leading to membranolysis.