Pharmacological blocking of microfibrillar-associated protein 4 reduces retinal neoangiogenesis and vascular leakage.

Neovascular age-related macular degeneration and diabetic macular edema are leading causes of vision-loss evoked by retinal neovascularization and vascular leakage. The glycoprotein microfibrillar-associated protein 4 (MFAP4) is an integrin αβ ligand present in the extracellular matrix. Single-cell transcriptomics reveal MFAP4 expression in cell-types in close proximity to vascular endothelial cells including choroidal vascular mural cells and retinal astrocytes and Müller cells.

The Cryo-EM structure of human CD163 bound to haptoglobin-hemoglobin reveals molecular mechanisms of hemoglobin scavenging.

CD163, a macrophage-specific receptor, plays a critical role in scavenging hemoglobin released during hemolysis, protecting against oxidative effects of heme iron. In the bloodstream, hemoglobin is bound by haptoglobin, leading to its immediate endocytosis by CD163. While haptoglobin's structure and function are well understood, CD163's structure and its interaction with the haptoglobin-hemoglobin complex have remained elusive.

Apolipoproteins L1 and L3 control mitochondrial membrane dynamics.

Apolipoproteins L1 and L3 (APOLs) are associated at the Golgi with the membrane fission factors phosphatidylinositol 4-kinase-IIIB (PI4KB) and non-muscular myosin 2A. Either APOL1 C-terminal truncation (APOL1Δ) or APOL3 deletion (APOL3-KO [knockout]) reduces PI4KB activity and triggers actomyosin reorganization. We report that APOL3, but not APOL1, controls PI4KB activity through interaction with PI4KB and neuronal calcium sensor-1 or calneuron-1.

Re-evalution of the measurement of haptoglobin in human plasma samples.

Haptoglobin (Hp) is an abundant plasma protein scavenging hemoglobin (Hb) CD163 on macrophages. This process consumes Hp, which therefore negatively correlates to hemolysis. However, exact measurements of Hp plasma levels are complicated by different phenotypes (Hp1-1, Hp2-1, and Hp2-2) forming different oligomeric states with differences in immunoreactivity.

Haptoglobin-related protein in human plasma correlates to haptoglobin concentrations and phenotypes.

Haptoglobin-related protein (Hpr) is a plasma protein with high sequence similarity to haptoglobin (Hp). Like Hp, Hpr also binds hemoglobin (Hb) with high affinity, but it does not bind to the Hb-Hp receptor CD163 on macrophages. The Hpr concentration is markedly lower than Hp in plasma and its regulation is not understood.