During
chronic obstructive pulmonary disease (
COPD) diaphragm and peripheral
muscle weakness occur. Muscle remodeling and wasting may be a result of apoptosis and changes in muscle-specific
transcription factors, such as MyoD, altering muscle-specific gene transcription and muscle regenerative capacity. To investigate this, we instilled under
ketamine/
xylazine anesthesia porcine
elastase in the lungs of hamsters to induce
emphysema. The emphysematous hamster is an accepted model for
COPD. In the diaphragm and peripheral muscles we assessed the occurrence of apoptosis, and in the diaphragm and soleus also the expression of MyoD and
inhibitor of differentiation protein 2 (Id2). There was no significant
muscle atrophy in emphysematous hamsters. The
mRNA levels of
TNF-alpha and markers of apoptosis were significantly elevated in the diaphragm and soleus muscles during
emphysema. This was accompanied by an increased presence of
nucleosomes in the cytosol.
Caspase 3 activity and the
DNA-binding activity of the p65 subunit of
NF-kappaB, however, were unaltered in all muscles. The
protein expression of MyoD and Id2 were decreased and increased in the diaphragm and the soleus muscle, respectively. Thus, despite the absence of
muscle atrophy in emphysematous hamsters, there was evidence of increased
TNF-alpha expression, apoptosis, and altered muscle-specific transcriptional regulation as reflected by decreased MyoD and elevated Id2 levels at least in the soleus and diaphragm muscle. These alterations may impair the regenerative capacity of skeletal muscles and ultimately contribute to muscle wasting.