Spinal microglia are dysregulated in a rat model of Pompe disease

Pompe disease is caused by mutation in the gene encoding alpha-glucosidase (GAA), an enzyme necessary for lysosomal glycogen degradation. Dysfunctional GAA results in widespread glycogen accumulation leading to muscle weakness, cardiovascular and breathing problems and premature death. Human autopsy studies and animal models confirm extensive neuropathology and motoneuron degeneration in Pompe disease. Neuroinflammation mediated by microglia is a common feature of neurodegenerative diseases and can contribute to ongoing pathology. In this study we investigated microglial transcriptional profile in a Pompe (Gaa-/-) rat model. We hypothesized that Pompe microglia have pro-inflammatory phenotype similar to other neurodegenerative disorders. Microglia were isolated from the C2-C7 spinal segments of 12-month-old female Pompe (n=5) and wild type Sprague Dawley rats (n=5). Microglial RNA was sequenced on Illumina NovaSeq 6000 platform. The expression of 1916 genes were upregulated in Pompe microglia (FDR p-value< 0.05). These genes were mapped to several neurodegenerative disease KEGG pathways including ALS and Huntington, Parkinson and Alzheimer disease. We also identified 1672 downregulated genes which were mapped to inflammatory KEGG pathways including Toll-like receptor signaling, NFκB signaling and NOD-like receptor signaling, all of which are necessary for cytokine/chemokine production. Of note, the expression of several inflammatory cytokines commonly increased in neurodegenerative disorders (e.g., IL6, IL1β, TNFα) were decreased in Pompe microglia. On the other hand, Pompe microglia also showed characteristics of disease-associated microglia (DAM) that are shared across several neurodegenerative disorders (Alzheimer disease, Parkinson disease and ALS) including upregulated levels of APOE, TREM2, SPP1 and downregulated CX3CR1. Because Pompe disease is characterized by dysfunctional lysosomes, and lysosomes are integral for phagocytosis, we also evaluated ex vivo microglial phagocytic function with an assay that utilized 1μm FluoroSpheres. In wild type rats, approximately 60% of microglia were phagocytic, whereas in Pompe rats only 20% of microglia were phagocytic. In concordance, some genes critical for phagocytic function such as mrc2 (mannose receptor c type-2), tfrc (transferrin receptor) and C3 (complement C3) were downregulated. Collectively, the results demonstrate that spinal microglia in the adult Pompe rat are not pro-inflammatory but do acquire some DAM characteristics. Further, Pompe microglia have impaired phagocytic function. These findings suggest that the microglial response to Pompe disease may differ from what has been described in other neurodegenerative disorders. However, the impact of microglia on neurodegeneration in Pompe disease remains to be elucidated. Funding: R01HD052682 (DDF and BJB), U01-NS116752-01A1 This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.