Parallels between arterial and cartilage calcification: what understanding artery calcification can teach us about chondrocalcinosis

Cardiovascular Disease Risk in Calcium Pyrophosphate Deposition Disease: A Nationwide Study of Veterans

OBJECTIVE

Calcium pyrophosphate deposition (CPPD) disease represents a common crystalline arthritis with a range of manifestations. Our goal was to investigate risks for cardiovascular events in patients with CPPD.

METHODS

We performed a retrospective matched cohort analysis in the Veterans Health Administration Corporate Data Warehouse, 2010-2014. CPPD was defined by ≥1 International Classification of Diseases, Ninth Revision codes for chondrocalcinosis or calcium metabolism disorder. CPPD patients were age- and sex-matched to approximately 4 patients without codes for CPPD; we excluded patients with a cardiovascular event during the 365 days prior to the index date. Demographic information, traditional cardiovascular risk factors, medications, and health care utilization were assessed at baseline. The primary outcome was a major adverse cardiovascular event (MACE: myocardial infarction, acute coronary syndrome, coronary revascularization, stroke, or death). Secondary outcomes included individual components of MACE. Cox proportional hazards models estimated fully adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

We identified 23,124 CPPD patients matched to 86,629 non-CPPD patients with >250,000 person-years of follow-up. The study population was 96% male, mean age was 78 years, and 75% were White. The frequency of traditional cardiovascular risk factors was similar between the 2 cohorts. CPPD was not significantly associated with risk for MACE (HR 0.98 [95% CI 0.94-1.02]) in fully adjusted models, though risks of myocardial infarction, acute coronary syndrome, and stroke were significantly higher in the CPPD cohort compared to the non-CPPD cohort.

CONCLUSION

CPPD did not confer an increased risk for MACE, a composite end point including all-cause mortality. Our results propose CPPD as a novel risk factor for MACE components, including myocardial infarction, acute coronary syndrome, and stroke.

Association of traditional cardiovascular risk factors in adults younger than 55 years with coronary heart disease. Case-control study

Objectives:

The traditional cardiovascular risk factors associated with coronary artery disease in individuals younger than 55 years old was determined in this study.

Methods:

A retrospective, paired case–control study comprised of patients younger than 55 years old who were admitted to the hospital due to acute coronary syndrome with coronary artery disease from 2011 to 2016. There were two controls per case, paired by age, gender, admission date, and health insurance. Data from patients were collected, such as sociodemographic information, cardiovascular risk factors, and drug therapy information. A conditional logistic regression model was created to evaluate the association between traditional cardiovascular risk factors and coronary artery disease.

Results:

There were 171 cases and 342 controls included in the study. The median age was 49 years, with a predominance of male gender (80.12%). Nearly 66% of cases had at least one traditional cardiovascular risk factor. The most common risk factors were obesity (57.31%), arterial hypertension (45.62%), and smoking (28.97%). Independent risk factors of coronary artery disease in patients younger than 55 years were arterial hypertension (odds ratio, 2.52; 95% confidence interval, 1.48–4.20; p = 0.001) and smoking (odds ratio, 7.15; 95% confidence interval, 3.19–15.99; p = 0.00). No significant association between diabetes mellitus and coronary heart disease in the global group (odds ratio, 2.04; 95% confidence innterval, 0.91–4.58; p = 0.083) was found.

Conclusion:

For patients younger than 55 years, with a theoretically lower risk of coronary artery disease due to their age, having one or several traditional risk factors (smoking, arterial hypertension, dyslipidemia, or diabetes mellitus) confers an increased risk of coronary artery disease regardless of age.

Bone status and aortic calcifications in chondrocalcinosis patients

Aim: We aimed to examine the association between several circulating bone turnover markers [ osteocalcin (OC), osteoprotegerin (OPG), beta-CrossLaps (β-CTx)], hip and spine bone mineral density (BMD) and abdominal aortic calcification (AAC) in patients with chondrocalcinosis (CC).

Methods: Thirty-six patients with CC and thirty-seven controls were consecutively enrolled in this pilot case-control, cross-sectional study. The following parameters were assessed: serum levels of OC, OPG and β-CTx by enzyme-linked immunosorbent assay (ELISA); hip and spine BMD by dual-energy X-ray absorptiometry and AAC score by lateral radiography.

Results: Patients with CC had higher levels of serum bone turnover markers and AAC score than the control group: OC [6.5 (3.5-9.9) vs 4.5 (2.6-7.2) ng/ml; p=0.05], OPG [(7.7 (6.2-9.4) vs 6.5 (5.5-8.12) pmol/ml; p=0.02], β-CTx [6078 (5870-6171) vs 5851 (5465-6109) pg/ml; p=0.02] and AAC score (3.6±6.2 vs 0.5±2; p=0.006). Conversely, even if statistical significance was not reached, hip and spine BMD was lower in patients with CC. Additionally, we found a positive correlation between OPG and AAC, but also between OPG and osteoporosis in patients with CC.

Conclusion: Patients with CC are characterized by higher circulating OC, OPG and β-CTx. The presence of AAC was more common in patients with CC, being only associated with serum OPG.

Prevalence of Diffuse Idiopathic Skeletal Hyperostosis in the General Elderly Population: A Japanese Cohort Survey Randomly Sampled From a Basic Resident Registry

STUDY DESIGN

This is a Japanese resident cohort study based on a municipal registry.

OBJECTIVES

In this study of an aged Japanese population, we used random sampling from the basic resident registry of a rural town for subject selection to investigate the prevalence of diffuse idiopathic skeletal hyperostosis (DISH) and effect of subject-related factors.

SUMMARY OF BACKGROUND

DISH is a condition characterized by the calcification and ossification of soft tissues. Interest is mounting on DISH as the elderly rate increases, but its pathogenetic mechanism remains unknown.

DATA

A total of 413 aged people randomly sampled from the resident registry of Obuse town.

MATERIALS AND METHODS

We established 8 groups on the basis of age (50s, 60s, 70s, and 80s) and sex after random sampling from the resident registry of Obuse town. A total of 411 participants (202 male and 209 female) were enrolled and underwent a single whole-spine lateral radiographic examination. We assessed for the existence of DISH and analyzed the effects of clinical factors using multivariate analysis.

RESULTS

A total of 72 (17.5%) participants were identified to have DISH in our population cohort. The prevalence of DISH tended to increase with age, being 3.1% in subjects in their 50s, 14.0% in their 60s, 24.3% in their 70s, and 29.0% in their 80s. According to multivariate analysis, hypertension (HT), male, bone mineral density (BMD), and aging were independent factors associated with DISH. The odds ratios of HT, male, and BMD were 1.93, 2.88, and 19.1, respectively.

CONCLUSIONS

This is the first study examining DISH in detail according to age and sex groups on a general population basis. Multivariate analysis revealed HT, male, BMD, and aging to be independent factors associated with DISH in the healthy community-dwelling elderly.

Thoracic aortic aneurysm is an independent factor associated with diffuse idiopathic skeletal hyperostosis

Aims

Although we often encounter patients with an aortic aneurysm who also have diffuse idiopathic skeletal hyperostosis (DISH), there are no reports to date of an association between these two conditions and the pathogenesis of DISH remains unknown. This study therefore evaluated the prevalence of DISH in patients with a thoracic aortic aneurysm (AA).

Patients and Methods

The medical records of 298 patients who underwent CT scans for a diagnosis of an AA or following high-energy trauma were retrospectively examined. A total of 204 patients underwent surgery for an AA and 94 had a high-energy injury and formed the non-AA group. The prevalence of DISH was assessed on CT scans of the chest and abdomen and the relationship between DISH and AA by comparison between the AA and non-AA groups.

Results

The prevalence of DISH in the AA group (114/204; 55.9%) was higher than that in the non-AA group (31/94; 33.0%). On multivariate analysis, the factors of AA, male gender, and ageing were independent predictors of the existence of DISH, with odds ratios of 2.9, 1.9, and 1.03, respectively.

Conclusion

This study revealed that the prevalence of DISH is higher in patients with an AA than in those without an AA, and that the presence of an AA significantly influenced the prevalence of DISH. Cite this article: Bone Joint J 2018;100-B:617-21.

Dystrophic calcinosis with both a huge calcified mass in the cervical spine and calcification in the chest wall in a patient with rheumatoid overlap syndrome

Dystrophic calcinosis in soft tissue occurs in damaged or devitalized tissues in the presence of normal calcium and phosphorous metabolism. It is often noted in subcutaneous tissues in patients with collagen vascular diseases and may involve a relatively localized area or be widespread. A 74-year-old Japanese woman with an overlap of rheumatoid arthritis, Sjögren's syndrome, and systemic sclerosis developed a huge tumor-like mass at the atlanto-axial vertebral joint region that caused severe cervical pain and difficulty in activities of daily living. She also had subcutaneous dystrophic calcification in the soft tissue of the chest wall. Calcinosis associated with systemic sclerosis is a well-recognized phenomenon, but a destructive paraspinal tumor in the cervical spine associated with overlap syndrome is extremely unique. Because calcinosis in spinal locations can be complicated by neurological involvement, patients with progressive symptoms may require surgical intervention. Surgical resection and biological therapy improved this patient's life and activities of daily living. Calcinosis is common in the conditions reviewed here, and different agents have been used for treatment. However, calcinosis management is poorly organized and lacks an accepted classification, systematic studies, and clinical therapeutic trials. The association of calcinosis and collagen vascular diseases is clinically and etiologically important. Although a combination of calcinosis and rheumatoid overlap syndrome is rare, various collagen vascular diseases may occur simultaneously. A perceptive diagnostic approach toward these diseases is critical, and early diagnosis and treatment are needed to prevent dystrophic calcinosis.

Central arterial aging and the epidemic of systolic hypertension and atherosclerosis

The structure and function of central arteries change throughout the lifetime of humans and animals. Since atherosclerosis and hypertension are prevalent in epidemic proportion among older persons, it is reasonable to hypothesize that specific mechanisms that underlie the arterial substrate that has been altered by an "aging process" are intimately linked to arterial diseases. Indeed, recent studies reveal a profile of arterial cell and matrix properties that emerges with advancing age within the grossly normal appearing aortic wall of both animals and humans. This profile is proinflammatory, and is manifested by intimal infiltration of fetal cells, increased production of angiotensin II (Ang II)-signaling pathway molecules, eg, matrix metalloproteases (MMPs), and monocyte chemoattractant protein (MCP-1), transforming growth factor B1 (TGF-beta1), enhanced activation of MMPs, TGF-beta, and NADPH oxidase, and reduced nitric oxide (NO) bioavailability. This profile is similar to that induced at younger ages in experimental animal models of hypertension or atherosclerosis. In humans, this proinflammatory state, which occurs in the absence of lipid deposition, appears to be attributable to aging, per se. Other well known human risk factors, eg, altered lipid metabolism, smoking, and lack of exercise, interact with this arterial substrate that is altered by aging and render the aging human artery fertile soil for facilitation of the initiation and progression of arterial diseases. Therapies to reduce or retard this age-associated proinflammatory state within the grossly appearing arterial wall central arteries, in addition to slowing arterial aging, per se, may have a substantial impact on the quintessential age-associated arterial diseases of our society.

Distinct patterns of gene expression in the superficial, middle and deep zones of bovine articular cartilage

Hyaline articular cartilage will not heal spontaneously, and lesions in hyaline articular cartilage often result in degenerative joint disease. Considerable progress has been made with respect to the responsive stem cells, inductive signals and extracellular scaffolding required for the optimal regeneration of cartilage. However, many challenges remain, such as topographic differences in the functional zones of articular cartilage. We hypothesized that a distinct set of differentially expressed genes define the surface, middle and deep zones of hyaline articular cartilage. Microarray analysis of bovine articular cartilage from the superficial and middle zones revealed 52 genes differentially expressed ≥ 10-fold and 114 additional genes differentially expressed ≥ five-fold. However, no genes were identified with a ≥ five-fold difference in expression when comparing articular cartilage from the middle and deep zones. There are distinct, differential gene expression patterns in the superficial and middle zones of hyaline articular cartilage that highlight the functional differences between these zones. This investigation has implications for the tissue engineering and regeneration of hyaline articular cartilage.

Genetics in arterial calcification: pieces of a puzzle and cogs in a wheel

Artery calcification reflects an admixture of factors such as ectopic osteochondral differentiation with primary host pathological conditions. We review how genetic factors, as identified by human genome-wide association studies, and incomplete correlations with various mouse studies, including knockout and strain analyses, fit into "pieces of the puzzle" in intimal calcification in human atherosclerosis, and artery tunica media calcification in aging, diabetes mellitus, and chronic kidney disease. We also describe in sharp contrast how ENPP1, CD73, and ABCC6 serve as "cogs in a wheel" of arterial calcification. Specifically, each is a minor component in the function of a much larger network of factors that exert balanced effects to promote and suppress arterial calcification. For the network to normally suppress spontaneous arterial calcification, the "cogs" ENPP1, CD73, and ABCC6 must be present and in working order. Monogenic ENPP1, CD73, and ABCC6 deficiencies each drive a molecular pathophysiology of closely related but phenotypically different diseases (generalized arterial calcification of infancy (GACI), pseudoxanthoma elasticum (PXE) and arterial calcification caused by CD73 deficiency (ACDC)), in which premature onset arterial calcification is a prominent but not the sole feature.

Cartilage biology, pathology, and repair

Osteoarthritis is one of the most common forms of musculoskeletal disease and the most prominent type of arthritis encountered in all countries. Although great efforts have been made to investigate cartilage biology and osteoarthritis pathology, the treatment has lagged behind that of other arthritides, as there is a lack of effective disease-modifying therapies. Numerous approaches for dealing with cartilage degradation have been tried, but enjoyed very little success to develop approved OA treatments with not only symptomatic improvement but also structure-modifying effect. In this review we discuss the most recent findings regarding the regulation of cartilage biology and pathology and highlight their potential therapeutic values.

Molecular mechanisms of cartilage remodelling in osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease that is characterized primarily by progressive breakdown of articular cartilage. The loss of proteoglycans, the mineralization of the extracellular matrix (ECM) and the hypertrophic differentiation of the chondrocytes constitute hallmarks of the disease. The pathogenesis of OA includes several pathways, which in single are very well investigated and partly understood, but in their complex interplay remain mainly unclear. This review summarises recent data on the underlying mechanisms, specifically with respect to cell-matrix interactions and cartilage mineralization. It points out why these findings are of importance for future OA research and for the development of novel therapeutic strategies to treat OA.

Hip geometry variation is associated with bone mineralization pathway gene variants: The Framingham Study

Mineralization of bone matrix is an important process in bone formation; thus defects in mineralization have been implicated in bone mineral density (BMD) and bone structure alterations. Three central regulators of phosphate balance, ALPL, ANKH, and ENPP1, are central in the matrix mineralization process; therefore, the genes encoding them are considered important candidates genes for BMD and bone geometry. To test for an association between these three candidate genes and BMD and bone geometry traits, 124 informative singlenucleotide polymorphisms (SNPs) were selected and genotyped in 1513 unrelated subjects from the Framingham offspring cohort. Initial results showed that SNP rs1974201 in the gene ENPP1 was a susceptibility variant associated with several hip geometric indices, with the strongest p value of 3.8 × 10(7) being observed for femoral neck width. A few modest associations were observed between SNPs in or near ALPL and several bone traits, but no association was observed with ANKH. The association signals observed for SNPs around rs1974201 were attenuated after conditional analysis on rs1974201. Transcription factor binding-site prediction revealed that the HOXA7 binding site was present in the reference sequence with the major allele, whereas this potential binding site is lost in the sequence with the minor allele of rs1974201. In conclusion, we found evidence for association of bone geometry variation with an SNP in ENPP1, a gene in the mineralization pathway. The alteration of a binding site of the deregulator of extracellular matrix HOXA7 warrants further investigation.

Microstructure and mineral composition of dystrophic calcification associated with the idiopathic inflammatory myopathies

INTRODUCTION

Calcified deposits (CDs) in skin and muscles are common in juvenile dermatomyositis (DM), and less frequent in adult DM. Limited information exists about the microstructure and composition of these deposits, and no information is available on their elemental composition and contents, mineral density (MD) and stiffness. We determined the microstructure, chemical composition, MD and stiffness of CDs obtained from DM patients.

METHODS

Surgically-removed calcinosis specimens were analyzed with fourier transform infrared microspectroscopy in reflectance mode (FTIR-RM) to map their spatial distribution and composition, and with scanning electron microscopy/silicon drift detector energy dispersive X-ray spectrometry (SEM/SDD-EDS) to obtain elemental maps. X-ray diffraction (XRD) identified their mineral structure, X-ray micro-computed tomography (microCT) mapped their internal structure and 3D distribution, quantitative backscattered electron (qBSE) imaging assessed their morphology and MD, nanoindentation measured their stiffness, and polarized light microscopy (PLM) evaluated the organic matrix composition.

RESULTS

Some specimens were composed of continuous carbonate apatite containing small amounts of proteins with a mineral to protein ratio much higher than in bone, and other specimens contained scattered agglomerates of various sizes with similar composition (FTIR-RM). Continuous or fragmented mineralization was present across the entire specimens (microCT). The apatite was much more crystallized than bone and dentin, and closer to enamel (XRD) and its calcium/phosphorous ratios were close to stoichiometric hydroxyapatite (SEM/SDD-EDS). The deposits also contained magnesium and sodium (SEM/SDD-EDS). The MD (qBSE) was closer to enamel than bone and dentin, as was the stiffness (nanoindentation) in the larger dense patches. Large mineralized areas were typically devoid of collagen; however, collagen was noted in some regions within the mineral or margins (PLM). qBSE, FTIR-RM and SEM/SDD-EDS maps suggest that the mineral is deposited first in a fragmented pattern followed by a wave of mineralization that incorporates these particles. Calcinosis masses with shorter duration appeared to have islands of mineralization, whereas longstanding deposits were solidly mineralized.

CONCLUSIONS

The properties of the mineral present in the calcinosis masses are closest to that of enamel, while clearly differing from bone. Calcium and phosphate, normally present in affected tissues, may have precipitated as carbonate apatite due to local loss of mineralization inhibitors.

Extraspinal manifestations of diffuse idiopathic skeletal hyperostosis

DISH is a condition characterized by calcification and/or ossification of soft tissues, mainly entheses, ligaments and joint capsules. Its prevalence increases with age and, therefore, DISH is a relatively common entity in the elderly. The classical site of involvement is the spinal column with right anterolateral soft tissue ossification being the most characteristic feature. However, DISH is not limited to the spine, and may affect multiple peripheral sites independently. Extraspinal entheseal ossifications are common and observing their isolated presence may lead to the diagnosis of DISH. Furthermore, hypertrophic or atypical OA observed in joints usually not affected by primary OA has frequently been reported in DISH. Several metabolic derangements and concomitant diseases have been suggested to be associated with DISH including obesity, increased waist circumference, hypertension, dyslipidaemia, diabetes mellitus (DM), hyperuricaemia, metabolic syndrome and an increased risk for cardiovascular diseases. Witnessing the present increase in lifespan, obesity, DM and metabolic syndrome in the Western population, the prevalence of DISH should be expected to rise. In order to increase the awareness for DISH, this review focuses on the extraspinal features of the condition.

Autocrine ATP release coupled to extracellular pyrophosphate accumulation in vascular smooth muscle cells

Extracellular inorganic pyrophosphate (PP(i)) is a potent suppressor of physiological calcification in bone and pathological calcification in blood vessels. Ectonucleotide pyrophosphatase/phosphodiesterases (eNPPs) generate PP(i) via the hydrolysis of ATP released into extracellular compartments by poorly understood mechanisms. Here we report that cultured vascular smooth muscle cells (VSMC) from rat aorta generate extracellular PP(i) via an autocrine mechanism that involves ATP release tightly coupled to eNPP activity. The nucleotide analog beta,gamma-methylene ATP (MeATP or AMPPCP) was used to selectively suppress ATP metabolism by eNPPs but not the CD39-type ecto-ATPases. In the absence of MeATP, VSMC generated extracellular PP(i) to accumulate >or=600 nM within 2 h while steadily maintaining extracellular ATP at 1 nM. Conversely, the presence of MeATP completely suppressed PP(i) accumulation while increasing ATP accumulation. Probenecid, which inhibits PP(i) efflux dependent on ANK, a putative PP(i) transporter or transport regulator, reduced extracellular PP(i) accumulation by approximately twofold. This indicates that autocrine ATP release coupled to eNPP activity comprises >or=50% of the extracellular PP(i)-generating capacity of VSMC. The accumulation of extracellular PP(i) and ATP was markedly attenuated by reduced temperature but was insensitive to brefeldin A, which suppresses constitutive exocytosis of Golgi-derived secretory vesicles. The magnitude of extracellular PP(i) accumulation in VSMC cultures increased with time postplating, suggesting that ATP release coupled to PP(i) generation is upregulated as cultured VSMC undergo contact-inhibition of proliferation or deposit extracellular matrix.

Preclinical vascular damage in white postmenopausal women: the relevance of osteoprotegerin

Osteoprotegerin (OPG) has recently been implicated in human atherogenesis. Abdominal obesity represents an established risk factor for the onset and development of atherosclerotic damage. The aim of the present study was to investigate the link between OPG and abdominal fat and the relationship to precocious features of atherosclerotic disease such as brachial flow-mediated vasodilation (FMV) and the intima-media thickening (IMT) in 195 white postmenopausal women (age range, 43-75 years). The study population was divided into 2 groups: group 1-waist circumference <80 cm and group 2-waist circumference > or = 80 cm. Group 2 had higher menopausal years, body mass index, low-density lipoprotein cholesterol, triglycerides, C-reactive protein, and carotid IMT. High-density lipoprotein cholesterol was higher in group 1. Afterward, these groups were divided on the basis of a cutoff value of OPG (6.85 pmol/L) that was the median of its distribution: patients with OPG < or = 6.85 pmol/L were OPG(-), and those with OPG >6.85 pmol/L were OPG(+). The OPG(+) subjects in both had lower brachial FMV and higher carotid IMT in comparison with OPG(-) subjects. At the multivariate regression analysis, waist circumference, high-density lipoprotein cholesterol, C-reactive protein, and OPG were predictors of carotid mean IMT (beta = 0.55, P = .001; beta = -0.14, P = .001; beta = 0.16, P = .001; and beta = 0.14, P = .05, respectively) and age, OPG, low-density lipoprotein cholesterol, and brachial diameter of brachial FMV (beta = -0.13, P = .05; beta = -0.25, P = .001; beta = -0.14, P = .024; and beta = 0.48, P = .001, respectively). The conclusions are as follows: first, OPG levels did not appear to be conditioned by a risk factor such as abdominal obesity; and second, OPG levels are mainly linked to the evidence of vascular damage. On this basis, we could speculate that OPG levels may be considered not a cardiovascular risk condition but a defense against atherosclerotic progression.

Mechanisms of Disease: ectonucleotide pyrophosphatase phosphodiesterase 1 as a 'gatekeeper' of insulin receptors

Insulin resistance is pathogenic for type 2 diabetes and cardiovascular disease. Several inhibitors of insulin signaling have a role in human insulin resistance. The transmembrane glycoprotein ectonucleotide pyrophosphatase phosphodiesterase 1 (E-NPP1; also known as plasma cell membrane glycoprotein PC-1) interacts with the insulin receptor and inhibits subsequent signaling by decreasing its beta-subunit autophosphorylation. E-NPP1 is overexpressed in skeletal muscle, adipose tissue and cultured skin fibroblasts of insulin-resistant individuals who are not yet obese or diabetic, which indicates that excessive E-NPP1 expression is an early, intrinsic defect in human insulin resistance. Genetic studies also support a primary role of E-NPP1 in insulin resistance. Among other variants, a missense polymorphism, Lys121Gln, has been described. The Gln121 variant is a stronger inhibitor than Lys121 of insulin receptor function, and is associated with insulin resistance, type 2 diabetes and both cardiovascular and nephrovascular complications in diabetic patients. E-NPP1 is measurable in human serum, where it might represent a valuable biomarker of insulin resistance, but its relationship to tissue and systemic insulin resistance remains to be thoroughly elucidated. Understanding the mechanisms that regulate E-NPP1 expression and/or function might render this protein a new target for strategies to treat and prevent type 2 diabetes and cardiovascular disease.

Calcium Deposition and Associated Chronic Diseases (Atherosclerosis, Diffuse Idiopathic Skeletal Hyperostosis, and Others)

Extracellular matrix mineralization or calcification occurs in many pathologic conditions, including atherosclerosis, medial wall calcification, diffuse idiopathic skeletal hyperostosis, and chondrocalcinosis. Vascular wall calcification is the most common and involves two mechanisms: passive calcification resulting from breakdown of the protection system and active calcification resulting from transdifferentiation of mesenchymal cells in the vascular wall to bone. Although reports are conflicting, several matrix proteins are identified as protective factors against dystrophic calcification in nonosseous tissues. Serum matrix Gla protein may be a marker of osteometabolic syndromes that cause hyperostosis and plays a role in Milwaukee shoulder syndrome.

Artériolopathie calcique (Calciphylaxie)

PURPOSE

Calcific arteriolopathy (CA), also known as " Calciphylaxis " describes a phenomenon of necrosis, mainly cutaneous and sometimes systemic, due to the obliteration of the arteriole's lumen. Initially there are under-intimal calcium deposits, and then the thrombosis occurs leading to the necrosis. CA affects mainly the renal insufficient hemodialysed patient, but not exclusively. We present 4 cases which illustrate well the etiologic spectrum of CA: terminal renal insufficiency, neoplasia, primary hyperparathyroidism, proteinuria, vitamin K inhibitors. We describe the AC's epidemiology, its cutaneous and systemic clinical presentations, its treatment. We make the hypothesis that CA is a strong risk marker in matter of cardiac mortality and we discuss this point.

CURRENT KNOWLEDGE AND KEY POINTS

In this article we describe the numerous breakthroughs that have been made in matter of research about calcification over the past few years: inhibitors of calcium phosphate deposition, vitamin D and PTH1R, protein-calcium complexes, cell death, induction of bone formation. These data are analysed from a clinical point of view with practical purposes. We present CA not only as a cutaneous disease but as a systemic pathology.

FUTURE PROSPECTS AND PROJECTS

The CA epidemiology is an incentive to more diagnosis suspicion in front of organ infarct involving a patient likely to be concerned by CA. The scientific and therapeutic breakthroughs in matter of calcification enable a better prevention of the disease. Nevertheless it remains very difficult to cure when installed.

Association of ENPP1 gene polymorphisms with hand osteoarthritis in a Chuvasha population

Periarticular calcification is a common attendant symptom of generalized arterial calcification of infancy, a rare Mendelian disorder caused by mutations of the gene coding for ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This prompted us to perform a family-based association study to test the hypothesis that genetic variation at the ENPP1 locus is involved in the etiology of osteoarthritis of the hand. The study population comprised 126 nuclear families with 574 adult individuals living in small villages in the Chuvasha and Bashkirostan autonomies of the Russian Federation. The extent of osteoarthritis was determined by analyzing plain hand radiographs. The outcome of a principal component analysis of osteoarthritis scores of a total of 28 joints of both hands was used as a primary phenotype in this study. Maximum likelihood estimates of the variance component analysis revealed a substantial contribution of genetic factors to the overall trait variance of about 25% in this homogeneous population. Three short tandem repeat (STR) polymorphisms – one intragenic and two flanking markers – and four single-nucleotide polymorphisms were tested. The markers tagged the ENPP1 locus at nearly equal intervals. We used three different transmission disequilibrium tests and obtained highly significant association signals. Alleles of the upstream microsatellite marker as well as several single-nucleotide polymorphism haplotypes consistently revealed the association. Thus, our data highlights variability of ENPP1 as an important genetic factor in the pathogenesis of idiopathic osteoarthritis.

Regulation of vascular calcification by osteoclast regulatory factors RANKL and osteoprotegerin

Vascular calcification often occurs with advancing age, atherosclerosis, various metabolic disorders such as diabetes mellitus and end-stage renal disease, or in rare genetic diseases, leading to serious clinical consequences. Such mineralization can occur at various sites (cardiac valves, arterial intima or media, capillaries), involve localized or diffuse widespread calcification, and result from numerous causes that provoke active inflammatory and osteogenic processes or disordered mineral homeostasis. Although valuable research has defined many key factors and cell types involved, surprising new insights continue to arise that deepen our understanding and suggest novel research directions or strategies for clinical intervention in calcific vasculopathies. One emerging area in vascular biology involves the RANKL/RANK/OPG system, molecules of the tumor necrosis factor-related family recently discovered to be critical regulators of immune and skeletal biology. Evidence is accumulating that such signals may be expressed, regulated, and function in vascular physiology and pathology in unique ways to promote endothelial cell survival, angiogenesis, monocyte or endothelial cell recruitment, and smooth muscle cell osteogenesis and calcification. Concerted research efforts are greatly needed to understand these potential roles, clarify whether RANKL (receptor activator of nuclear factor kappaB ligand) promotes and osteoprotegerin (OPG) protects against vascular calcification, define how OPG genetic polymorphisms relate to cardiovascular disease, and learn whether elevated serum OPG levels reflect endothelial dysfunction in patients. Overall, the RANKL/RANK/OPG system may mediate important and complex links between the vascular, skeletal, and immune systems. Thus, these molecules may play a central role in regulating the development of vascular calcification coincident with declines in skeletal mineralization with age, osteoporosis, or disease.

Calcinosis in Rheumatic Diseases

BACKGROUND

Calcinosis, or dystrophic soft-tissue calcification, occurs in damaged or devitalized tissues in the presence of normal calcium/phosphorus metabolism. It is often noted in the subcutaneous tissues of connective tissues diseases--primarily systemic lupus erythematosus, scleroderma, or dermatomyositis--and may involve a relatively localized area or be widespread. The calcinotic accumulations may lead secondarily to muscle atrophy, joint contractures, and skin ulceration complicated by recurrent episodes of local inflammation and infection.

OBJECTIVES

To review the classification, pathogenesis, clinical features, and treatment of calcinosis in rheumatic diseases.

METHOD

A MEDLINE search of articles from 1972 to 2004 was conducted utilizing the index word "calcinosis" with the coindexing terms "scleroderma," "lupus," "dermatomyositis," and "dystrophic calcification."

RESULTS

Calcinosis may be the source of both pain and disability in connective tissue disease patients. Illustrative cases of patients with severe calcinosis are described. The literature available was critically reviewed. While warfarin, colchicine, probenecid, bisphosphonates, diltiazem, minocycline, aluminum hydroxide, salicylate, surgical extirpation, and carbon dioxide laser therapies have been used, no treatment has convincingly prevented or reduced calcinosis.

CONCLUSIONS

Calcinosis is common in the conditions reviewed and a number of agents have been used for treatment. However, the approach to calcinosis management is disorganized, beginning with the lack of a generally accepted classification and continuing with a lack of systematic study and clinical therapeutic trials.

Calcification of advanced atherosclerotic lesions in the innominate arteries of ApoE-deficient mice: potential role of chondrocyte-like cells

OBJECTIVE

Advanced atherosclerotic lesions in the innominate arteries of chow-fed apolipoprotein E-deficient mice become highly calcified with 100% frequency by 75 weeks of age. The time course, cell types, and mechanism(s) associated with calcification were investigated.

METHODS AND RESULTS

The deposition of hydroxyapatite is preceded by the formation of fibro-fatty nodules that are populated by cells that morphologically resemble chondrocytes. These cells are spatially associated with small deposits of hydroxyapatite in animals between 45 and 60 weeks of age. Immunocytochemical analyses with antibodies recognizing known chondrocyte proteins show that these cells express the same proteins as chondrocytes within developing bone. Histological and electron microscopic analyses of lesions from animals between 45 and 60 weeks of age show that the chondrocyte-like cells are surrounded by dense connective tissue that stains positive for type II collagen. Nanocrystals of hydroxyapatite can be seen within matrix vesicles derived from the chondrocyte-like cells. In mice between 75 and 104 weeks of age, the lesions have significantly reduced cellularity and contain large calcium deposits. The few remaining chondrocyte-like cells are located adjacent to or within the large areas of calcification.

CONCLUSIONS

Calcification of advanced lesions in chow-fed apolipoprotein E-deficient mice occurs reproducibly in mice between 45 and 75 weeks of age. The deposition of hydroxyapatite is mediated by chondrocytes, which suggests that the mechanism of calcification may in part recapitulate the process of endochondral bone formation.

Diffuse idiopathic skeletal hyperostosis: Forestier's disease

Diffuse idiopathic skeletal hyperostosis (DISH) or Forestier's disease is characterized by calcification and ossification of soft tissue entheses of ligaments and tendons. DISH is believed to be a variant of osteoarthritis (OA) without the degenerative intervertebral disc and joint degenerative qualities seen in classic OA. The likely pathoetiologic causes of DISH are presented.

New developments in our understanding of DISH (diffuse idiopathic skeletal hyperostosis)

PURPOSE OF REVIEW

Diffuse idiopathic skeletal hyperostosis (DISH) or Forestier's disease is a common disorder among older adults. The diagnosis is based solely on radiographic abnormalities defined using the Resnick criteria. DISH is characterized by ossification of the anterior longitudinal ligament of the spine and various extraspinal ligaments. DISH often coexists with OA, but patients affected by this disorder differ from patients with primary OA in several aspects: prevalence in the general population, gender distribution, anatomic site of primary involvement, magnitude and distribution in the spine and the peripheral joints. Purpose of this review is to summarize new clinical, pathogenetic and therapeutic insights of this disease.

RECENT FINDINGS

Recent studies confirm that patients with DISH have a greater body mass index, higher serum uric acid levels and are more likely to have diabetes mellitus. In addition, DISH is most probably related to abnormal bone cell growth/activity reflecting the influence of metabolic factors that lead to new bone formation. Serum matrix Gla protein may be a marker of osteometabolic syndromes, such as DISH, that cause hyperostosis.

SUMMARY

Many recent developments of DISH are described in this review. Possible pathogenetic mechanism driving bone deposition are discussed. DISH is still recognized radiographically; no specific drug has been yet identified.

Genetic determinants of arterial calcification associated with atherosclerosis

Increasing research interest has focused on arterial calcification in the setting of atherosclerosis. Many features of atherosclerosis-related calcification provide useful clinical information. For example, calcium mineral deposits frequently form in atherosclerotic plaque, and intimal arterial calcification can be used as a surrogate marker for atherosclerosis; also, calcium deposits are readily and noninvasively quantified, which is useful because greater amounts of coronary calcification predict a higher risk of myocardial infarction and death. Several mechanisms leading to calcification associated with atherosclerosis have been proposed; however, no direct testing of proposed mechanisms has yet been reported. Studies in genetically altered animals and in humans have shed light on potential genetic determinants, which in turn could form the basis for a more comprehensive understanding of the factors affecting calcification within plaque and the associated pathobiologic implications. We review proposed molecular and cellular mechanisms of atherosclerosis-associated arterial calcification, summarize genetic influences, and suggest areas in which further investigation is needed. Understanding the molecular and genetic determinants of specific structural plaque components such as calcification can provide a solid foundation for the development of novel therapeutic approaches to favorably alter plaque structure and minimize vulnerability to arterial rupture.

Mutations in ENPP1 are associated with 'idiopathic' infantile arterial calcification

Idiopathic infantile arterial calcification (IIAC; OMIM 208000) is characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. We analyzed affected individuals from 11 unrelated kindreds and found that IIAC was associated with mutations that inactivated ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This cell surface enzyme generates inorganic pyrophosphate (PP(i)), a solute that regulates cell differentiation and serves as an essential physiologic inhibitor of calcification.