Postnatal development of the collagen matrix in rabbit tibial plateau articular cartilage

Changes in the 3-dimensional arrangement of the articular cartilage matrix during growth of the rabbit tibial plateau were studied. Knees from newborn, and 1, 2 and 6 wk-old rabbits were compared with those of adults by light and electron microscopy. The specimens were fixed, embedded en bloc in epoxy resin and sectioned vertically/coronally through the point where the articular cartilage was thickest in the adult medial tibial plateau. At birth, the proximal tibial epiphysis was cartilaginous, but nascent articular cartilage was recognisable as a densely cellular layer covering the tibial condyle. Within 30 μm of the articular surface, the chondrocytes were flattened and collagen fibres ran among these cells in a direction parallel to the surface. Deeper in the articular cartilage, rounded cells were evenly distributed within a random collagen fibril network. At the centre of the plateau, the tangential layer changed little during growth, whereas the subjacent cellular layer grew in thickness and steadily achieved a more vertical character in the organisation of its constituent collagen and cellular elements. At 1 wk, cells were separated into clusters by acellular regions filled with collagen fibrils. At 2 wk, cells within the forming radial zone were aligned in columns bracketed by vertical collagen fibres. Continuity of these vertical fibres with those in the tangential surface layer was evident at this age. The chondrocytes were surrounded by fibrous capsules typical of chondrons. By 6 wk, the bases of the radial collagen fibres in the very centre of the condyle had calcified, as had the adjacent hypertrophic hyaline cartilage. A solid subchondral plate and tidemark did not appear until skeletal maturity. From birth to age 6 wk, maximum thickness of the layer identified as primordial articular cartilage increased from 0.13 mm to 0.70 mm, and was 1.5 mm in the adult. Throughout growth, however, the thickness of the tangential layer in the centre of the plateau never exceeded 0.05 μm. In the patella, femoral head and peripheral tibial plateau, cartilage development followed the same general sequence. In contrast to the central tibial plateau, the tangential layer also grew in thickness, but at a slower rate than that of the radial zone. At all ages, the developing articular cartilage was structurally distinct from the deeper hyaline cartilage which contributed to growth of the ossification centre through enchondral ossification. The collagen matrix of articular cartilage acquires a characteristic, orderly 3-dimensional structure soon after birth. Growth in cartilage thickness occurs primarily through enlargement of the radial zone.     

An essential role for CCL3 in the development of collagen antibody-induced arthritis

CCL3 is a C–C family chemokine detected at high levels in the synovial tissue and fluids of rheumatoid arthritis (RA) patients. CCL3 binds to the chemokine receptors CCR1 and CCR5, which are expressed by inflammatory leukocytes such as macrophages and T cells present in the affected joints of RA patients. The present study was undertaken to investigate whether absence of CCL3 prevented development of inflammation and joint destruction in anti-type II collagen monoclonal antibody (anti-CII mAb)-induced arthritis. “CCL3 null mice were different from wild-type control mice in terms of body weight loss”. In addition, CCL3 null mice exhibited milder clinical and histopathological scores following administration of anti-CII mAb and endotoxin. Moreover, the release of TNF in response to systemic administration of endotoxin was not affected in CCL3 null mice compared to wild-type mice, indicating that the phenotype was not attributable to a defect in endotoxin response. These results indicate that CCL3 plays an essential role in the development of inflammation and joint destruction induced by anti-CII mAb.     

The expanded collagen VI family: new chains and new questions

Abstract

Collagen VI is a component of the extracellular matrix of almost all connective tissues, including cartilage, bone, tendon, muscles and cornea, where it forms abundant and structurally unique microfibrils organized into different suprastructural assemblies. The precise role of collagen VI is not clearly defined although it is most abundant in the interstitial matrix of tissues and often found in close association with basement membranes. Three genetically distinct collagen VI chains, α1(VI), α2(VI) and α3(VI), encoded by the COL6A1. COL6A2 and COL6A3 genes, were first described more than 20 years ago. Their molecular assembly and role in congenital muscular dystrophy has been broadly characterized. In 2008, three additional collagen VI genes arrayed in tandem at a single gene locus on chromosome 3q in humans, and chromosome 9 in mice, were described. Following the naming scheme for collagens the new genes were designated COL6A4. COL6A5 and COL6A6 encoding the α4(VI), α5(VI) and α6(VI) chains, respectively. This review will focus on the current state of knowledge of the three new chains.     

The ultrastructure of spiralled collagen in liver fibrosis

An ultrastructural study was performed using o?long tea polyphenols for staining liver tissue from 5 patients with acute hepatitis, 20 patients with chronic hepatitis, and 5 patients with alcoholic liver disease. Spiralled collagen was seen in the region of the portal tract in all of the patients, but not in the periportal region, perisinusoidal region, or sinusoidal wall. The amount of spiralled collagen relative to the total amount of collagen fibrils was greater in patients with hepatitis than in those with alcoholic liver disease. The occurrence of spiralled collagen appears to be a degenerative phenomenon as indicated by observations of its three-dimensional structure.     

Effect of hyaluronate on physicochemical and biological properties of collagen solution which could be used as collagen filler

The effect of hyaluronate (HA) on the physicochemical and biological properties of collagen solution was examined for two preparations of collagen with different rates of fibril formation. The addition of HA to the collagen preparation with the slower rate of fibril formation caused a prominent acceleration of fibril formation. A differential scanning calorimetric measurement of the collagen preparation demonstrated a stabilizing effect of HA on collagen solution after incubation at 37°C. Histochemical examination of rat dermis after injection of the collagen solution into the tissue revealed the migration of fibroblast-like cells into the region occupied by the injected collagen. The addition of HA to collagen preparation S (slower rate of fibril formation) shortened the timeto-appearance of fibroblast-like cells to a similar value to that observed when collagen preparation F (faster rate of fibril formation) was used. The timing of cell appearance was in accord with the rate of fibril formation in vitro. Fibrils newly formed by injected collagen might provide sites for cell attachment, migration and proliferation.     

Type II collagen distribution during cranial development in Xenopus laevis

Epithelially expressed type II collagen is thought to play a prominent role in the embryonic patterning and differentiation of the vertebrate skull, primarily on the basis of data derived from amniotes. We describe the spatiotemporal distribution of type II collagen in the embryonic head of the African clawed frog, Xenopus laevis, using whole-mount and serial-section immunohistochemical analysis. We studied embryos spanning Nieuwkoop and Faber (1967) stages 21–39, a period including cranial neural crest cell migration and ending immediately before the onset of neurocranial chondrogenesis. Xenopus displays a transient expression of type II collagen beginning at least as early as stage 21; staining is most intense and widespread at stages 33/34 and 35/36 and subsequently diminishes. Collagen-positive areas include the ventrolateral surface of the brain, sensory vesicles, notochord, oropharynx, and integument. This expression pattern is similar, but not identical, to that reported for the mouse and two bird species (Japanese quail, domestic fowl); thus epithelially expressed type II collagen appears to be a phylogenetically widespread feature of vertebrate cranial development. Consistent with the proposed role of type II collagen in mediating neurocranial differentiation, most collagen-positive areas lie adjacent to subsequent sites of chondrogenesis in the neurocranium but not the visceral skeleton. However, much of the collagen is expressed after the migration of cranial neural crest, including presumptive chondrogenic crest, seemingly too late to pattern the neurocranium by entrapment of these migrating cells.     

Humanized antibody to human interleukin-6 receptor inhibits the development of collagen arthritis in cynomolgus monkeys

In the present study, we demonstrated the anti-arthritic effect of humanized anti-human IL-6 receptor (IL-6R) antibody, MRA, in cynomolgus monkey. MRA can react with monkey IL-6R and block signal transduction of IL-6. Collagen-induced arthritis (CIA) was induced by twice immunizing with bovine type II collagen (CII) emulsified with complete adjuvant. MRA was intravenously injected once a week, from the day of the first collagen immunization, for 13 weeks. The symptoms of arthritis were evaluated using a visual scoring system and radiography. Inflammatory parameters (C-reactive protein (CRP), fibrinogen, and erythrocyte sedimentation rate (ESR) and concentrations of anti-CII antibody, anti-MRA antibody, and MRA were monitored regularly. At the end of the study, histological evaluation was carried out. MRA, at a dose of 10 mg/kg, gave rise to statistically significant suppression. The elevation of serum CRP and fibrinogen levels and ESR were also inhibited. Furthermore, radiographic and histological examination showed that MRA treatment suppressed joint destruction. Our results demonstrate that IL-6 plays an important role in monkey CIA and that MRA may be an attractive agent for the treatment of rheumatoid arthritis.     

Accumulation of type VI collagen in the primary osteon of the rat femur during postnatal development

In rodents, the long bone diaphysis is expanded by forming primary osteons at the periosteal surface of the cortical bone. This ossification process is thought to be regulated by the microenvironment in the periosteum. Type VI collagen (Col VI), a component of the extracellular matrix (ECM) in the periosteum, is involved in osteoblast differentiation at early stages. In several cell types, Col VI interacts with NG2 on the cytoplasmic membrane to promote cell proliferation, spreading and motility. However, the detailed functions of Col VI and NG2 in the ossification process in the periosteum are still under investigation. In this study, to clarify the relationship between localization of Col VI and formation of the primary osteon, we examined the distribution of Col VI and osteoblast lineages expressing NG2 in the periosteum of rat femoral diaphysis during postnatal growing periods by immunohistochemistry. Primary osteons enclosing the osteonal cavity were clearly identified in the cortical bone from 2 weeks old. The size of the osteonal cavities decreased from the outer to the inner region of the cortical bone. In addition, the osteonal cavities of newly formed primary osteons at the outermost region started to decrease in size after rats reached the age of 4 weeks. Immunohistochemistry revealed concentrated localization of Col VI in the ECM in the osteonal cavity. Col VI-immunoreactive areas were reduced and they disappeared as the osteonal cavities became smaller from the outer to the inner region. In the osteonal cavities of the outer cortical regions, Runx2-immunoreactive spindle-shaped cells and mature osteoblasts were detected in Col VI-immunoreactive areas. The numbers of Runx2-immunoreactive cells were significantly higher in the osteonal cavities than in the osteogenic layers from 2 to 4 weeks. Most of these Runx2-immunoreactive cells showed NG2-immunoreactivity. Furthermore, PCNA-immunoreactivity was detected in the Runx2-immunoreactive spindle cells in the osteonal cavities. These results indicate that Col VI provides a characteristic microenvironment in the osteonal cavity of the primary osteon, and that differentiation and proliferation of the osteoblast lineage occur in the Col VI-immunoreactive area. Interaction of Col VI and NG2 may be involved in the structural organization of the primary osteon by regulating osteoblast lineages.     

Chondrocytes synthesize type I collagen and accumulate the protein in the matrix during development of rat tibial articular cartilage

The present study was designed to investigate whether or not chondrocytes in articular cartilage express type I collagen in vivo under physiological conditions. Expressions of the gene and the phenotype of type I collagen were examined in rat tibial articular cartilage in the knee joint during development. Knee joints of Wistar rats at 1, 5, and 11 weeks postnatal were fixed in 4% paraformaldehyde with or without 0.5% glutaraldehyde and decalcified in 10% EDTA. After the specimens were embedded in paraffin and serial sections made, adjacent sections were processed for immunohistochemistry and in situ hybridization for type I collagen. The epiphysis of the tibia was composed of cartilage in week-1 rats. Formation of articular cartilage was in progress in week 5 as endochondral ossification proceeded and was completed in week 11. Anti-type I collagen antibody stained only the superficial area of the epiphysis in week 1, but the immunoreactivity was expanded into the deeper region of the articular cartilage with development in weeks 5 and 11. Hybridization signals for pro-alpha 1 (I) collagen were seen in some of chondrocytes in the epiphysis of the week-1 tibia. The most intense signals were identified in chondrocytes in week 5 and the signals appeared weaker in week 11. The present study demonstrated that chondrocytes synthesize type I collagen and accumulate the protein in the matrix during development of the articular cartilage.     

长间距胶原的超微结构及其性质

目的：着重讨论长间距胶原（ＬＳＣ）的超微结构特征及其性质；方法：经电镜观察和免疫组化化染色，对１７例恶性肿瘤，１１例良性雪旺细胞瘤和２例椎间盘脱出症的髓核进行研究，结果：ＬＳＣ可分为３种类型，即小体型、疏散型和单股型。小体型和疏散型和ＬＳＣ可见于某些肿瘤的胞质内，结论：ＬＳＣ形态学特征类似胶原，但它的的确切性质仍不清楚，可能不是真性胶原，至少可以说在胞质的ＬＳＣ不是胶原。     

常用蛋白交联方法及其对胶原的影响

由于胶原材料在体内存在降解问题 ,为此目前常用各种方法使胶原发生交联 ,以提高其抗降解能力及机械性能 ,以便于临床引导组织再生的操作与应用。本文将就目前常用交联方法及其对胶原的机械性能、生物学性能的影响作一综述。     

无细胞胶原基质的研究进展

天然胶原类组织,经过脱细胞处理后,降低免疫原性,可作为组织工程的支架材料,本文就脱细胞的方法以及无细胞胶原基质的研究进展作一综述。     

醛固酮对人胎儿心脏成纤维细胞增殖以及胶原表达的影响

目的:探讨人胎儿心脏成纤维细胞(FCFS)经不同浓度的醛固酮(ALD)干预后增殖的变化以及对细胞中I、III型胶原表达的影响。方法:采用胶原酶II消化法、差速贴壁法、差速脱壁法获取并纯化FCFS,在不同浓度醛固酮作用下,应用CCK-8活细胞计数试剂盒检测细胞的增殖率。应用RT-PCR方法检测细胞中I型胶原前胶原A1(COL1A1)和III型胶原前胶原A1(COL3A1)mRNA的变化,应用Western blot检测COL1A1、COL3A1蛋白表达的变化。结果:ALD可浓度依赖性促-进FCFS增殖;低浓度的ALD(10-9、10-8、10-7mol/L)可明显促进FCFS中COL1A1、COL3A1表达,而10-6mol/L的ALD没有明显作用,10-5mol/L的ALD甚至起到抑制作用。结论:ALD可促进FCFS的细胞增殖,其增殖程度随浓度升高而升高;ALD在一定浓度范围内可以促进COL1A1和COL3A1表达,高浓度ALD对两种分子表达具有抑制作用。     

Denaturation of type II collagen in articular cartilage in experimental murine arthritis. Evidence for collagen degradation in both reversible and irreversible cartilage damage

Degradation of type II collagen is thought to be a key step in the destruction of articular cartilage in patients with rheumatoid arthritis or osteoarthritis. The aim of this study was to investigate whether type II collagen degradation is associated with cartilage destruction. Type II collagen degradation was studied in two murine arthritis models, zymosan-induced arthritis (ZIA), which develops reversible articular cartilage damage based on proteoglycan analysis, and antigen-induced arthritis (AIA), in which there is irreversible damage to the cartilage. Type II collagen degradation was assayed immunohistochemically using the COL2-3/4m antibody which recognizes denatured type II collagen, such as is produced by collagenase cleavage. In both models, degradation of type II collagen was observed in the non-calcified articular cartilage of arthritic but not of control knees. In the patella-femoral compartment, collagen denaturation started to increase on day 3 (ZIA) and day 7 (AIA) and remained high on day 14. In contrast, in the tibia-femoral compartment, type II collagen breakdown was not increased before 14 days in either model. By 28 days, collagen denaturation was strongly reduced in the patella-femoral compartment in the ZIA model, but persisted in the tibia-femoral compartment in both models. In conclusion, increased type II collagen degradation was found in articular cartilage of both ZIA and AIA animals. Since ZIA does not develop irreversible cartilage destruction, this indicates that cartilage may have the ability to withstand a limited degree of type II collagen degradation without developing irreversible damage. Copyright © 1999 John Wiley & Sons, Ltd.     

高度近视相关胶原基因的研究进展

高度近视(high myopia)又称病理性近视,其屈光度≤-6.00 D,伴有眼轴的延长和眼基质的改变,是一种致盲的重要器质性眼病.家族性高度近视具有明显的遗传性,符合孟德尔遗传规律,但其致病基因尚未确定.巩膜胶原表达和积聚异常导致眼球过度扩张被认为是高度近视形成的重要机制,因此胶原基因与高度近视的关系已经引起关注.已有研究表明COLA1基因与高度近视相关,同时多种伴有高度近视症状的综合征的致病基因均为胶原基因,以上证据表明胶原基因可能是高度近视的致病基因并应成为高度近视相关基因的重要研究方向.该文就高度近视相关胶原基因的研究进展进行综述.     

Semiquantitative analysis of collagen types in the hypertrophied left ventricle

Cardiac fibrosis is a characteristic feature of left ventricular hypertrophy. The aim of this study was to develop a simple and accurate method to analyse collagen accumulation, taking into account the variation in cardiac muscle fibre orientation and nonuniform collagen distribution. This technique was used to determine the amount and types of collagen that accumulate during pressure overload cardiac hypertrophy. These data were correlated with myocyte size, and with the diastolic stress–strain relationship of the intact myocardium. Myocyte size was significantly increased in the hypertrophied hearts, compared with age and sex matched controls (control 363±25 μm² vs experimental 244μm²; mean± S.E. , P < 0.05). No overall collagen accumulation was observed in the hypertrophied hearts, but a significant increase in collagen I was found with a reduction in the amount of collagen III in experimental animals. Since no increase in diastolic stiffness of the hearts was observed, these results indicate that an increase in the overall collagen content of the heart, rather than the upregulation of a specific type, may be necessary to cause diastolic dysfunction.