Targeting cell-type-specific, choroid-peripheral immune signaling to treat age-related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of blindness featuring pathogenic neovascularization of the choroidal vasculature (CNV). Although systemic immunity plays a role in AMD, the ocular signals that recruit and activate immune cells remain poorly defined. Using single-cell RNA sequencing, we prospectively profile peripheral blood mononuclear cells from 65 individuals including AMD and controls, which we integrate with existing choroid data. We generate a network of choroid-peripheral immune interactions dysregulated in AMD, including known AMD-relevant gene vascular endothelial growth factor (VEGF) receptor 2. Additionally, we find CYR61 is upregulated in choroidal veins and may signal to circulating monocytes. In mice, we validate that CYR61 is abundant in endothelial cells within CNV lesions neighboring monocyte-derived macrophages. Mechanistically, CYR61 activates macrophage anti-angiogenic gene expression, and ocular Cyr61 knockdown increases murine CNV size, indicating CYR61 inhibits CNV. This study highlights the potential of multi-tissue human datasets to identify disease-relevant and potentially therapeutically modifiable targets.

Toll-like receptor 4 is critical for the development of resection-associated hepatic steatosis.

BACKGROUND: A significant number of children with short bowel syndrome experience intestinal failure-associated liver disease. We recently demonstrated accelerated hepatic steatosis after 50% small bowel resection (SBR) in mice. Since SBR is associated with alterations in the gut microbiome, the purpose of this study was to determine whether TLR4 signaling is critical to the development of resection-associated hepatic steatosis. METHODS: Male C57BL6 (control) and TLR4-knockout (KO) mice underwent 50% proximal SBR. Liver sections were analyzed to obtain the percent lipid content, and Ileal sections were assessed for morphological adaptation. Intestinal TLR4 mRNA expression was measured at 7days and 10weeks. RESULTS: Compared to controls, TLR4 KO mice demonstrated similar weight gain and morphological adaptation after SBR. Hepatic steatosis was decreased 32-fold in the absence of TLR4. Intestinal TLR4 mRNA expression was significantly elevated 7days after SBR. We also found that TLR4 expression in the intestine was 20-fold higher in whole bowel sections compared with isolated enterocytes. CONCLUSIONS: TLR4 signaling is critical for the development of resection-associated steatosis, but not involved in intestinal adaptation after massive SBR. Further studies are needed to delineate the mechanism for TLR4 signaling in the genesis of resection-associated liver injury. LEVEL OF EVIDENCE: Animal study, not clinical.