Heat shock proteins (HSPs) are often upregulated following oxidative and other forms of stress. Based on reports of excessive
apoptosis in torn supraspinatus tendon and mechanically loaded tendon cells, we hypothesized heat shock proteins may be present
in rodent and human models of tendinopathy due to their central role in caspase dependent apoptotic cell signaling. We used
a running rat supraspinatus tendinopathy overuse model with custom microarrays to investigate the process at a genetic level.
Additionally torn supraspinatus tendon and matched intact subscapularis tendon samples were collected from patients undergoing
arthroscopic shoulder surgery. Control samples of subscapularis tendon were collected from 10 patients undergoing arthroscopic
stabilization surgery and evaluated using semiquantative RT-PCR and immunohistochemistry. We identified substantial upregulation
of heat shock proteins and apoptotic genes in the rodent model. We further confirmed increased levels of heat shock protein
and apoptotic regulatory genes in human supraspinatus and subscapularis tendon. This finding suggests heat shock proteins
play a role in the cascade of stress-activated programmed cell death and degeneration in tendinopathy and may provide a novel
target in preventing tendinopathies.
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patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the animal and human protocol for this investigation and that
all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation
in the study was obtained.