Expression analysis of genes involved in collagen cross-linking and its regulation in traumatic anterior shoulder instability.

The molecular alterations involved in the capsule deformation presented in shoulder instability patients are poorly understood. Increased TGFß1 acts as a signal for production of matrix macromolecules by fibrogenic cells at joint injury sites. TGFß1, through its receptor TGFßR1, regulates genes involved in collagen cross-linking, such as LOX, PLOD1, and PLOD2. We evaluated TGFß1, TGFßR1, LOX, PLOD1, and PLOD2 gene expression in the antero-inferior (macroscopically injured region), antero-superior and posterior regions of the glenohumeral capsule of 29 shoulder instability patients and eight controls. We observed that PLOD2 expression was increased in the anterior-inferior capsule region of the patients compared to controls. LOX expression tended to be increased in the posterior portion of patients. Patients with recurrent shoulder dislocation presented upregulation of TGFßR1 in the antero-inferior capsule portion and of PLOD2 in the posterior region. Conversely, LOX was increased in the posterior portion of the capsule of patients with a single shoulder dislocation episode. In the antero-inferior, LOX expression was inversely correlated and TGFßR1 was directly correlated with the duration of symptoms. In the posterior region, PLOD2, TGFß1, and TGFßR1 were directly correlated with the duration of symptoms. In conclusion, PLOD2 expression was increased in the macroscopically injured region of the capsule of patients. Upregulation of TGFß1, TGFßR1, and PLOD2 seems to be related with the maintenance of disease symptoms, especially in the posterior region. LOX upregulation seems to occur only in the initial phase of the affection. Therefore, TGFß1, TGFßR1, LOX, and PLOD2 may play a role in shoulder instability.

Gene expression analysis in patients with traumatic anterior shoulder instability suggests deregulation of collagen genes.

Shoulder dislocation occurs in 1-2% of the population. Capsular deformation is a key factor in shoulder dislocation; however, little is known about capsule biology. We evaluated, for the first time in literature, the expression of COL1A1, COL1A2, COL3A1 and COL5A1 in the antero-inferior, antero-superior and posterior regions of the glenohumeral capsule of 31 patients with anterior shoulder instability and eight controls. The expression of collagen genes was evaluated by quantitative reverse transcription-PCR. The expression of COL1A1, COL3A1 and the ratio of COL1A1/COL1A2 were increased in all three portions of the capsule in patients compared to controls (p < 0.05). COL1A2 expression was upregulated in the antero-superior and posterior sites of the capsule of patients (p < 0.05). The ratio of COL1A2/COL3A1 expression was reduced in capsule antero-inferior and posterior sites of patients compared to controls (p < 0.05). In the capsule antero-inferior site of patients, the ratios of COL1A1/COL5A1, CO1A2/COL5A1 and COL3A1/COL5A1 expression were increased (p < 0.05). In patients, COL1A1/COL5A1 was also increased in the posterior site (p < 0.05). We found deregulated expression of collagen genes across the capsule of shoulder instability patients. These molecular alterations may lead to modifications of collagen fibril structure and impairment of the healing process, possibly with a role in capsular deformation.

Changes of histology and capsular collagen in a rat shoulder immobilization model.

BACKGROUND: Shoulder immobilization can induce adhesion of the joint, capsular contracture or lead to the condition of frozen shoulder. However, little is known about the histological effects of immobilization on the shoulder joint. This study aimed to explore the effect of immobility on the subscapular bursa (SSB) and the joint capsular content, including the distribution of types I and III collagen, within an immobilized rat shoulder. METHODS: Forty-six Sprague-Dawley rats were randomly divided into one control group (n = 6) and four immobilization groups (n = 10 in each group), in which the left shoulders were immobilized with plaster for 1, 2, 3 and 4 weeks. At the end of each time point, 2 rats from each group were euthanized and shoulders prepared for serial histological observations of the glenohumeral joints, as well as picrosirius red and immunohistochemical observation of type III collagen. Histological sections of the remaining rat shoulders were used for the immunohistochemical detection of the capsular content of types I and III collagen. RESULTS: The hyperplastic synovium of the anterior capsule obstructed the communication between the SSB and the glenohumeral joint cavity at 2 and 3 weeks. The adhesion of the SSB appeared at 3 and 4 weeks. The quantitative and qualitative results showed that the capsular contents of types I and III collagen progressively increased at 2, 3 and 4 weeks, and that type III collagen was distributed extensively within the joint capsule at 2 and 3 weeks. CONCLUSION: Immobilization of the rat shoulder induced synovial hyperplasia of the joint capsule, adhesion of the SSB and an increase of the capsular content of types I and III collagen.

[Distribution pattern of subchondral mineralization in the glenoid cavity in normal subjects, athletes and patients]. / Verteilungsmuster der subchondralen Mineralisierung in der Cavitas Glenoidalis bei Normalpersonen, Sportlern und Patienten.

To get information on the stresses acting on the shoulder joint, the distribution of subchondral mineralisation was examined by means of CT-Osteo-absorptiometry in the glenoid cavity in healthy people, athletes and patients. In young persons two density maxima are found ventrally and dorsally older persons, however, show a centrally located maximum which suggests a different joint mechanics in different ages depending on the decreasing physiological incongruence. In gymnasts the overall mineralisation is significantly higher, maxima are found centrally or shifted dorsally. In patients with recurrent dislocation of the shoulder or instability the zone of highest density is shifted to the edges of the glenoid cavity indicating that the prevailing position of the resultant force is excentric. By means of CT-Osteo-absorptiometry these individual patterns of mineralisation can be displayed in the living and can give information on the individual mechanical situation ("loading history") of a joint.