Lysophosphatidic acid derivative is a novel candidate of therapeutic agents for a mouse model of frontotemporal dementia with progranulin deficiency

Frontotemporal dementia (FTD) is driven by progranulin haploinsufficiency, in which age-dependent microglial activation promotes neurodegeneration through TDP-43 proteinopathy. Cyclic phosphatidic acid (cPA) is a natural phospholipid mediator characterized by a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. A pharmacologically active derivative of cPA has been shown to suppress microglial activation. Based on this, we aimed to investigate the potential of cPA derivatives to prevent the onset of FTD. Specifically, we administered metabolically stabilized cPA derivatives, 2-carba-cPA (2ccPA) and its degradation product, 2-carba-LPA (2cLPA), to presymptomatic progranulin-deficient (Grn^-/-) mice. The mice received intraperitoneal injections of 0.9 mg/kg/day of either compound for 6 months. Treatment with 2ccPA, but not 2cLPA, significantly attenuated thalamic neuronal loss, cytoplasmic TDP-43 aggregation, and microglial activation, including reduced transition to an ameboid morphology. These findings led us to hypothesize that 2ccPA mitigates disease onset by suppressing microglial activation. To test this, we examined the effects of 2ccPA on primary Grn^-/- microglia and found that treatment reduced markers of accelerated senescence, phagocytic activity, lipid accumulation, and CCL8 secretion. Collectively, our findings identify 2ccPA as a promising candidate for the prevention of FTD. This study also represents a conceptual advance by demonstrating that targeting microglial activation is an effective strategy to delay or attenuate neurodegeneration in FTD.