Post-hemorrhagic hydrocephalus (PHH) is a neurological disease that primarily affects premature infants and involves infiltration of blood into the brain's ventricles followed by excessive accumulatio Show more
Post-hemorrhagic hydrocephalus (PHH) is a neurological disease that primarily affects premature infants and involves infiltration of blood into the brain's ventricles followed by excessive accumulation of cerebrospinal fluid (CSF), leading to ventricular enlargement and increased intracranial pressure. The precise mechanisms driving PHH development and persistence are incompletely understood and lack disease-modifying treatments. Using a mouse model of PHH, we have identified transcriptomic, proteomic, and cellular features of PHH involving neuroimmune and neurovascular alterations recapitulating those reported in human disease. Improvement upon a lysophosphatidic acid (LPA)-induced PHH mouse model was combined with unbiased proteomic and single-nucleus transcriptomics that identified microglial molecular pathways propagating PHH. Pharmacological depletion of microglia in vivo significantly reduced PHH-associated ventriculomegaly. These data identify microglial and neurovascular elements in the development of PHH, implicating them as other potentially tractable therapeutic targets beyond LPA receptors, towards developing medical treatments for PHH. Show less
HDL-bound ApoM and albumin are protein chaperones for the circulating bioactive lipid, sphingosine 1-phosphate (S1P); in this role, they support essential extracellular S1P signaling functions in the Show more
HDL-bound ApoM and albumin are protein chaperones for the circulating bioactive lipid, sphingosine 1-phosphate (S1P); in this role, they support essential extracellular S1P signaling functions in the vascular and immune systems. We previously showed that ApoM- and albumin-bound S1P exhibit differences in receptor activation and biological functions. Whether the physiological functions of S1P require chaperones is not clear. We examined ApoM-deficient, albumin-deficient, and double-KO (DKO) mice for circulatory S1P and its biological functions. In albumin-deficient mice, ApoM was upregulated, thus enabling S1P functions in embryonic development and postnatal adult life. The Show less
GPCR inhibitors are highly prevalent in modern therapeutics. However, interference with complex GPCR regulatory mechanisms leads to both therapeutic efficacy and adverse effects. Recently, the sphingo Show more
GPCR inhibitors are highly prevalent in modern therapeutics. However, interference with complex GPCR regulatory mechanisms leads to both therapeutic efficacy and adverse effects. Recently, the sphingosine-1-phosphate (S1P) receptor inhibitor FTY720 (also known as Fingolimod), which induces lymphopenia and prevents neuroinflammation, was adopted as a disease-modifying therapeutic in multiple sclerosis. Although highly efficacious, dose-dependent increases in adverse events have tempered its utility. We show here that FTY720P induces phosphorylation of the C-terminal domain of S1P receptor 1 (S1P₁) at multiple sites, resulting in GPCR internalization, polyubiquitinylation, and degradation. We also identified the ubiquitin E3 ligase WWP2 in the GPCR complex and demonstrated its requirement in FTY720-induced receptor degradation. GPCR degradation was not essential for the induction of lymphopenia, but was critical for pulmonary vascular leak in vivo. Prevention of receptor phosphorylation, internalization, and degradation inhibited vascular leak, which suggests that discrete mechanisms of S1P receptor regulation are responsible for the efficacy and adverse events associated with this class of therapeutics. Show less