Enhanced alpha 1(I) mRNA expression in frozen shoulder and dupuytren tissue

The purpose of this study has been to investigate collagen I and III synthesis during the fibrosing stage of frozen shoulder and Dupuytren samples in comparison to normal capsule tissue. - By using the quantitative PCR significantly increased levels of alpha 1(I) mRNA transcription in samples of frozen shoulder (p = 0.016) and Duypuytren (p = 0.041) could be demonstrated, whereas alpha 2(I) and alpha 1(III) chains have shown the same mRNA levels as in normal capsule tissue. - Despite an enhancement of alpha 1(I) mRNA transcription in frozen shoulder and Dupuytren samples the intracellular precursor procollagen I and extracellular mature collagen I was detected immunohistochemically in reduced levels. - The structural alteration of collagen I assembly might be caused by disturbed post-translation from the polypeptide chains into the triple helices procollagen I though alpha 1(I) mRNA transcription was significantly increased and alpha 2(I) mRNA transcription was in normal range. Fibroblasts might release high quantities of free alpha 1(I) polypeptide chains or (alpha 1(I)) 3 homotrimer into the extracellular space during the fibrosing stage of frozen shoulder and Dupuytren disease. - In all samples neither differences of alpha 1(III) mRNA transcription nor differences of immunohistochemical staining intensity of collagen III could be seen. This might result from apoptosis of myofibroblasts in the final phase of the fibrosing processes. - The stimulating effect of insulin-like growth factor type I (IGF-I) to induce fibrosis in connective tissue such as scarlet is known. In all patients suffering from frozen shoulder and Dupuytren disease the serum IGF-I level was in a normal range and the IGF-I receptor - (IGFR-I) mRNA transcription in the samples was also in the same level compared with normal capsule tissue.