Therapeutic acute intermittent hypoxia modestly improves breathing in Pompe disease

Pompe disease is an autosomal recessive neuromuscular disorder characterized by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for lysosomal glycogen degradation in all cells. Respiratory distress is a common symptom among patients with Pompe disease resulting from weakness of primary respiratory neuromuscular units of the diaphragm and genioglossus and the motor neurons which innervate them. The only FDA approved treatment is enzyme replacement therapy (ERT) of recombinant human GAA (rhGAA) which slows the decline of motor function and extends life expectancy. However, ERT does not cross the blood-brain barrier and thus, is unable to treat the critical pathology present in motor neurons hindering long-term efficacy. In the present study, we sought to explore an alternative treatment for Pompe patients to improve breathing by improving the function of motor neurons. Therapeutic acute intermittent hypoxia (tAIH) is a non-invasive therapeutic modality which has had success in improving respiratory and non-respiratory motor function in patients with spinal cord injury, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Here, we treated adult Gaa^-/- mice with a single, week-long tAIH protocol, followed by bi-weekly tAIH for 4 months. We report three critical findings: (1) both short and long-term tAIH therapy modestly improve breathing in Gaa^-/- mice; (2) long-term tAIH-therapy in WT mice moderately elevates breathing responses; and (3) these trending improvements to respiration in Gaa^-/- may be related to changes in chemoreflex activation, reduced kyphosis, and improved overlap of acetylcholine receptors and phrenic motor neuron axon terminals in the diaphragm muscle.