Expression of type I collagen in the capsule of a contracture knee in a rat model

Accumulation of advanced-glycation end products (AGEs) accelerates arthrogenic joint contracture in immobilized rat knee

Joint mobility decreases in the elderly and in diabetics, this process is thought to be caused by accumulation of advanced-glycation end products (AGEs). Here, we aimed to elucidate the role of AGEs in joint contracture formation in rat knees. Rats were injected with ribose or saline into the knees twice weekly for 8 weeks. Pentosidine (AGE) levels were measured in the knee-joint tissues. After serial injections, rats were subjected to unilateral knee-joint immobilization in a flexion position for various periods. At day 21, the passive knee ranges of motions (ROMs) were measured. Knee joint histopathology were assessed, and the expression of fibrotic genes in the posterior joint capsules was examined using real-time PCR. Ribose injection induced a 7.0-fold increase in pentosidine levels relative to saline injection. Joint immobilization resulted in equal myogenic ROM restriction in both groups. Arthrogenic ROM restriction was greater with ribose injection in the immobilized joints (p < 0.05), but was not affected in nonimmobilized joints. Type-I (COL1A1) and type-III (COL3A1) collagen gene expression increased significantly in immobilized joints relative to nonimmobilized joints in the ribose group, but was not affected in the saline group. Ribose injection increased COL1A1 expression slightly and COL3A1 expression significantly in immobilized joints. Histologically, inflammatory changes appeared at day 3 of immobilization and peaked at day 7. These responses trended to be more severe and prolonged in the ribose group than in the saline group. Our data provide evidence for a causal relationship between AGEs and joint contracture formation following immobilization. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:854-863, 2018.

Intra-articular collagenase injection increases range of motion in a rat knee flexion contracture model

Objectives

A knee joint contracture, a loss in passive range of motion (ROM), can be caused by prolonged immobility. In a rat knee immobilization flexion contracture model, the posterior capsule was shown to contribute to an irreversible limitation in ROM, and collagen pathways were identified as differentially expressed over the development of a contracture. Collagenases purified from Clostridium histolyticum are currently prescribed to treat Dupuytren’s and Peyronie’s contractures due to their ability to degrade collagen. The potential application of collagenases to target collagen in the posterior capsule was tested in this model.

Materials and methods

Rats had one hind leg immobilized, developing a knee flexion contracture. After 4 weeks, the immobilization device was removed, and the rats received one 50 µL intra-articular injection of 0.6 mg/mL purified collagenase. Control rats were injected with only the buffer. After 2 weeks of spontaneous remobilization following the injections, ROM was measured with a rat knee arthrometer, and histological sections were immunostained with antibodies against rat collagen types I and III.

Results/conclusion

Compared with buffer-injected control knees, collagenase-treated knees showed increased ROM in extension by 8.0°±3.8° (p-value <0.05). Immunohistochemical analysis revealed an increase in collagen type III staining (p<0.01) in the posterior capsule of collagenase-treated knees indicating an effect on the extracellular matrix due to the collagenase. Collagen I staining was unchanged (p>0.05). The current study provides experimental evidence for the pharmacological treatment of knee flexion contractures with intra-articular collagenase injection, improving the knee ROM.

Effects of joint immobilization on changes in myofibroblasts and collagen in the rat knee contracture model

The purpose of this study was to examine the time-dependent changes in the development of joint capsule fibrosis and in the number of myofibroblasts in the joint capsule after immobilization, using a rat knee contracture model. Both knee joints were fixed in full flexion for 1, 2, and 4 weeks (immobilization group). Untreated rats were bred for each immobilization period (control group). Histological analysis was performed to evaluate changes in the amount and density of collagen in the joint capsule. The changes in type I and III collagen mRNA were examined by in situ hybridization. The number of myofibroblasts in the joint capsule was assessed by immunohistochemical methods. In the immobilization group, the amount of collagen increased within 1 week and the density of collagen increased within 2 weeks, as compared with that in the control group. Type I collagen mRNA-positive cell numbers in the immobilization group increased at all time points. However, type III collagen mRNA-positive cell numbers did not increase. Myofibroblasts in the immobilization group significantly increased compared with those in the control group at all time points, and they increased significantly with the period of immobilization. These results suggest that joint capsule fibrosis with overexpression of type I collagen occurs and progresses within 1 week after immobilization, and an increase in myofibroblasts is related to the mechanism of joint capsule fibrosis. The findings suggest the need for a treatment targeting accumulation of type I collagen associated with an increase in myofibroblasts. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1998-2006, 2017.

Expression patterns of collagen types I and III in the capsule of a rat knee contracture model

Our objective was to determine the changes in expression of collagen types I and III in the capsule of a rat knee contracture model. The unilateral knee joints of adult male rats were rigidly immobilized at 150 degrees of flexion using a rigid plastic plate and screws for 3 days, 1, 2, 4, 8, and 16 weeks (immobilized group). Sham-operated animals had holes drilled in the femur and tibia with screws inserted without a plate (control group). The expression patterns of collagen types I and III in the anterior and posterior capsule were evaluated by in situ hybridization (ISH), quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry (IHC), and Western blotting (WB). Expressions of collagen types I and III were decreased after immobilization compared to the control group by ISH and qPCR. The expression was not changed after immobilization compared to the control group by IHC and WB. The expression of mRNA and protein levels of collagen types I and III were not increased after immobilization, which indicated that accumulation of the two types of collagen was not the etiology of joint contracture. Another process, such as capsule and synovial adhesions, may be one possible cause of joint contracture.

Expression of collagen types I and II on articular cartilage in a rat knee contracture model

The purpose of our study was to clarify the expression patterns of collagen types I and II on articular cartilage after immobilization in a rat knee contracture model in 3 specific areas (noncontact area, transitional area, contact area). The unilateral knee joints of adult male rats were rigidly immobilized at 150 degrees of flexion using screws and a rigid plastic plate. Sham-operated animals had holes drilled in the femur and the tibia and screws inserted but were not plated. The expression patterns of collagen types I and II in each area were evaluated by in situ hybridization (ISH), immunohistochemistry (IHC), and quantitative real-time polymerase chain reaction (qPCR). The expression of collagen type II in the noncontact area was decreased by ISH but appeared unchanged when examined by IHC. In the transitional and contact areas, the expression of collagen type II was initially shown to have decreased and then increased at the hypertrophic chondrocytes by ISH but appeared decreased by IHC. Quantitative PCR revealed the decreased expression of type II collagen in the contact area. Immunostaining of collagen type I was increased at the noncontact area and transitional areas. Alterations of collagen types I and II expression may also affect the degeneration of articular cartilage after immobilization and the changes were different in the three areas.

Increased expression of metalloproteinase-8 and -13 on articular cartilage in a rat immobilized knee model

Joint immobilization is commonly used for the treatment of joint injuries and diseases, but it also causes cartilage degeneration. Damage to the fibrillar meshwork of type II collagen in the articular cartilage is a critical event for cartilage degeneration. Collagenases such as matrix metalloproteinase (MMP)-8 and MMP-13 have been considered the main enzymes responsible for the degradation of type II collagen. However, the mechanism of the articular cartilage degeneration after immobilization has not been revealed. The purpose of this study was to examine changes of the expression patterns of MMP-8 and MMP-13 after rigid immobilization of the knee joint. The unilateral knee joints of adult male rats were rigidly immobilized at 150 degrees of flexion using an internal fixator. Histological sections from the medial midcondylar region of the knee were obtained and evaluated in 3 specific areas (non-contact, transitional, and contact areas). The expression of MMP-8 and MMP-13 was evaluated by in situ hybridization. Total RNA was extracted from the articular cartilage in the contact area, and expression levels of MMP-8 and MMP-13 mRNAs were measured by quantitative real-time polymerase chain reaction. Localization of MMP-13 expression was also examined by immunohistochemistry. The expression of MMP-8 mRNA was decreased by 1 week after immobilization. After 4-week immobilization, hypertrophic differentiated chondrocytes were observed in the transitional and contact areas, and the expression of MMP-8 and MMP-13 mRNAs was increased in the chondrocytes. Rigid immobilization is associated with the increased expression of MMP-8 and MMP-13 in the hypertrophic differentiated chondrocytes. These two collagenases may play an important role in the articular cartilage degeneration after joint immobilization.

Intra-articular injection of hyaluronan diminishes loss of chondrocytes in a rat immobilized-knee model

Joint immobilization is a useful and common treatment modality in orthopedics. However, it also causes unfavorable outcome such as articular cartilage degeneration. Intra-articular injection of hyaluronan has been accepted as a treatment of osteoarthritis, but its effects on immobilized joint remain to be clarified. Hyaluronan is a polysaccharide, distributed ubiquitously in various tissues. In this study, we examined the effect of hyaluronan on the articular cartilage in immobilized joints. The unilateral knee joints of adult male rats were immobilized at 150 degrees in flexion with an internal plate and screws for 1, 2, 4, 6, 8, 12, or 16 weeks (n = 84). Hyaluronan or saline (50 microl/each injection) was administered intra-articularly on the day of surgery and once a week. The articular cartilage from the medial midcondylar region of the knee was obtained, and divided into non-contact, contact and transitional areas (between the non-contact and the contact areas). In each area, a degree of degeneration was evaluated by histomorphometric grading, and measurements of thickness and number of chondrocytes. Histological grading scores in the hyaluronan group were smaller at 12 and 16 weeks compared with those in the saline group. The thickness of the articular cartilage increased in the transitional area in both groups. The number of chondrocytes in the contact and transitional areas gradually decreased, but their number in the hyaluronan group was greater at 12 and 16 weeks compared with that in the saline group. Hyaluronan showed chondroprotective effects on the articular cartilage in a rat immobilized-knee model.