Diabetic dyslipidemia, common in type 1 and type 2 diabetes (T2D), contributes to the pathogenesis of DR. LXR activation enhances cholesterol removal by reverse cholesterol transport (RCT) and reduces inflammatory gene expression. Systemic inflammation in diabetes is mediated, in part, by myeloidosis in the bone marrow (BM), which contributes to the pathogenesis of DR. We sought to test whether the progression of DR could be reduced by administering the novel LXR modulator, DMHCA (8mg/kg/body weight/day), in a T2D mouse model for 6 months. Retinal tissue was assessed by flow cytometry and Mass spectroscopy. LXR activation by DMHCA reduced cholesterol levels through the conversion to oxysterols and demosterol and was associated with a reduction of inflammatory cells in the retina and systemic circulation. Increased levels of long-term (17±1 vs. 11±2 db/db) and decrease levels of multipotent progenitors (MPP) (35±1 vs. 41±2 db/db) were noted in total bone marrow cells from db/db mice. DMHCA reduced the production of granulocyte-progenitors (GMP) (16 ± 1 vs. 22±3 db/db) and restored levels of NRF-2 (1±0.2 vs. 3±1 db/db) in bone marrow (BM) of db/db. DMHCA increased the number of myeloid angiogenic cells in the systemic circulation of db/db (0.04%±0.003 vs. 0.01%±0.002 db/db). Single cell RNA-seq analysis was performed using hematopoietic stem cells (HSCs) from untreated db/db and DMHCA treated db/db bone marrow. DMHCA treated HSCs showed upregulated genes associated with the activator protein 1 (AP-1) complex. AP-1 complexes regulate different stages of HSC differentiation along most of the myeloid lineage. Together, these findings reveal that LXR activation, via DMHCA treatment, decreases systemic and tissue-specific inflammation by controlling the production of pro-inflammatory stem cells and reducing oxidative injury in the BM of T2D mice.
C.P. Vieira: None. S.D. Fortmann: None. A. Longhini: None. T.A. Lydic: None. J.V. Busik: None. M.B. Grant: None.
National Institutes of Health (EY025383, EY012601)