Summary Caspase-11, a cytosolic endotoxin (lipopolysaccharide: LPS) receptor, mediates pyroptosis, a lytic form of cell death. Caspase-11-dependent pyroptosis mediates lethality in endotoxemia, but it is unclear how LPS is delivered into the cytosol for the activation of caspase-11. Here we discovered that hepatocyte-released high mobility group box 1 (HMGB1) was required for caspase-11-dependent pyroptosis and lethality in endotoxemia and bacterial sepsis. Mechanistically, hepatocyte-released HMGB1 bound LPS and targeted its internalization into the lysosomes of macrophages and endothelial cells via the receptor for advanced glycation end-products (RAGE). Subsequently, HMGB1 permeabilized the phospholipid bilayer in the acidic environment of lysosomes. This resulted in LPS leakage into the cytosol and caspase-11 activation. Depletion of hepatocyte HMGB1, inhibition of hepatocyte HMGB1 release, neutralizing extracellular HMGB1, or RAGE deficiency prevented caspase-11-dependent pyroptosis and death in endotoxemia and bacterial sepsis. These findings indicate that HMGB1 interacts with LPS to mediate caspase-11-dependent pyroptosis in lethal sepsis.

The complete three-dimensional orientations of single gold nanorods (AuNR) were successfully resolved by using a standard optical darkfield microscope through deciphering the field distribution pattern in the slightly defocused darkfield images. The resulting images depend on the aspect ratio of the AuNR, the numerical aperture of the objective, the defocusing distance, and the polarization direction of the incident radiation. Interpretation of the observed images is facilitated by comparing them with a series of simulated images with different parameters. The experimental data matched well with the simulated results, and the reliability of this technique was further verified with polarization modulation experiments. Since deconvolution can be performed off-line after the images are recorded, this approach essentially allows video-rate data acquisition. The convenient, reliable and rapid angle-resolving capability should enable broad applications in imaging studies in many scientific fields.

Here we demonstrated a simple yet powerful method, planar illumination microscopy, to directly track the rotational and translational diffusion dynamics of individual anisotropic nanoparticles in solution and living cells. By illuminating gold nanorods (GNRs) with two orthogonal sheets of light and resolving the polarized scattering signal with a birefringent crystal, we readily achieved three-dimensional angular resolving capability for single GNRs in noisy surroundings. The rotational dynamics of individual GNRs dispersed in glycerol/water mixtures with different chemical modification were tracked, and the measured rotational diffusion coefficient was well fitted to a previously reported theoretical model (Torre, J. G. d. l.; Martinez, M. C. L. Macromolecules 1987, 20, 661-666; Tirado, M. M.; Torre, J. G. d. l. J. Chem. Phys. 1980, 73, 1986-1993). In addition, the translational and rotational movements of individual GNRs transported by kinesin motor protein on microtubules inside living cells were directly imaged. Compared to its motion in free solution, a GNR attached to motor-protein did not rotate significantly while moving forward. Our method can be further generalized to allow determination of three-dimensional orientation of single dipoles using many different illumination modes.

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Alzheimer's disease (AD) is a progressive and irreversible brain disorder. Recent studies revealed the pivotal role of β-amyloid (Aβ) in AD. However, there is no conclusive indication that the existing therapeutic strategies exerted any effect on the mitigation of Aβ-induced neurotoxicity and the elimination of Aβ aggregates simultaneously in vivo. Herein, we developed a novel nanocomposite that can eliminate toxic Aβ aggregates and mitigate Aβ-induced neurotoxicity in AD mice. This nanocomposite was designed to be a small-sized particle (14 ± 4 nm) with Aβ-binding peptides (KLVFF) integrated on the surface. The nanocomposite was prepared by wrapping a protein molecule with a cross-linked KLVFF-containing polymer layer synthesized by in situ polymerization. The presence of the nanocomposite remarkably changed the morphology of Aβ aggregates, which led to the formation of Aβ/ nanocomposite coassembled nanoclusters instead of Aβ oligomers. With the reduction of the pathological Aβ oligomers, the nanocomposites attenuated the Aβ-induced neuron damages, regained endocranial microglia's capability to phagocytose Aβ, and eventually protected hippocampal neurons against apoptosis. Thus, we anticipate that the small-sized nanocomposite will potentially offer a feasible strategy in the development of novel AD treatments.