Small-molecule GSDMD agonism in tumors stimulates antitumor immunity without toxicity.

Gasdermin-mediated inflammatory cell death (pyroptosis) can activate protective immunity in immunologically cold tumors. Here, we performed a high-throughput screen for compounds that could activate gasdermin D (GSDMD), which is expressed widely in tumors. We identified 6,7-dichloro-2-methylsulfonyl-3-N-tert-butylaminoquinoxaline (DMB) as a direct and selective GSDMD agonist that activates GSDMD pore formation and pyroptosis without cleaving GSDMD.

The NK cell receptor NKp46 recognizes ecto-calreticulin on ER-stressed cells.

Natural killer (NK) cell kill infected, transformed and stressed cells when an activating NK cell receptor is triggered. Most NK cells and some innate lymphoid cells express the activating receptor NKp46, encoded by NCR1, the most evolutionarily ancient NK cell receptor. Blockage of NKp46 inhibits NK killing of many cancer targets.

Fluorescent probes for and quantification of hydrogen peroxide.

Hydrogen peroxide (HO) plays essential roles in redox signaling and oxidative stress, and its dynamic concentration is critical to human health and diseases. Here we report the design, syntheses, and biological applications of and for quantitative measurement of HO. Both probes were successfully applied to detect endogenous HO fluxes in living cells or zebrafish, and biological effects of multiple stress inducers including rotenone, arsenic trioxide, and starvation were investigated.

HDAC6 mediates an aggresome-like mechanism for NLRP3 and pyrin inflammasome activation.

Inflammasomes are supramolecular complexes that play key roles in immune surveillance. This is accomplished by the activation of inflammatory caspases, which leads to the proteolytic maturation of interleukin 1β (IL-1β) and pyroptosis. Here, we show that nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3)- and pyrin-mediated inflammasome assembly, caspase activation, and IL-1β conversion occur at the microtubule-organizing center (MTOC).

FDA-approved disulfiram inhibits pyroptosis by blocking gasdermin D pore formation.

Cytosolic sensing of pathogens and damage by myeloid and barrier epithelial cells assembles large complexes called inflammasomes, which activate inflammatory caspases to process cytokines (IL-1β) and gasdermin D (GSDMD). Cleaved GSDMD forms membrane pores, leading to cytokine release and inflammatory cell death (pyroptosis). Inhibiting GSDMD is an attractive strategy to curb inflammation.

Small-Molecule-Based Fluorescent Sensors for Selective Detection of Reactive Oxygen Species in Biological Systems.

Reactive oxygen species (ROS) encompass a collection of intricately linked chemical entities characterized by individually distinct physicochemical properties and biological reactivities. Although excessive ROS generation is well known to underpin disease development, it has become increasingly evident that ROS also play central roles in redox regulation and normal physiology. A major challenge in uncovering the relevant biological mechanisms and deconvoluting the apparently paradoxical roles of distinct ROS in human health and disease lies in the selective and sensitive detection of these transient species in the complex biological milieu.

Tandem Payne/Dakin Reaction: A New Strategy for Hydrogen Peroxide Detection and Molecular Imaging.

Hydrogen peroxide (H O ) has been recognized as one of the most significant ROS (reactive oxygen species) in human health and disease. Because of the intrinsic attributes of H O -such as its low reactivity under physiological pH-it is exceedingly challenging to develop small-molecule fluorescent probes with high selectivity and sensitivity for visualization of H O in an intricate biological milieu. To address this gap, a rationally designed tandem Payne/Dakin reaction is reported that is specific to molecular recognition of H O .

: a fluorescent hypochlorous acid probe for live-cell and imaging and quantitative application in flow cytometry and a 96-well microplate assay.

Ultra-selective and ultra-sensitive probes for hypochlorous acid (HOCl), one of the most poorly understood reactive oxygen species (ROS), are urgently needed to unravel the HOCl functions in important biological processes such as development and innate immunity. Based on a selective oxidative -dearylation reaction of 2,6-dichlorophenol toward HOCl over other reactive oxygen species, we have developed a novel fluorescent probe for HOCl detection with ultra-selectivity, ultra-sensitivity and a rapid turn-on response. The functional robustness of for endogenous HOCl detection and imaging has been thoroughly scrutinized in multiple types of phagocytes and imaging of live intact zebrafish embryos.

Fluorescent Probe HKSOX-1 for Imaging and Detection of Endogenous Superoxide in Live Cells and In Vivo.

Superoxide anion radical (O2(•-)) is undoubtedly the most important primary reactive oxygen species (ROS) found in cells, whose formation and fate are intertwined with diverse physiological and pathological processes. Here we report a highly sensitive and selective O2(•-) detecting strategy involving O2(•-) cleavage of an aryl trifluoromethanesulfonate group to yield a free phenol. We have synthesized three new O2(•-) fluorescent probes (HKSOX-1, HKSOX-1r for cellular retention, and HKSOX-1m for mitochondria-targeting) which exhibit excellent selectivity and sensitivity toward O2(•-) over a broad range of pH, strong oxidants, and abundant reductants found in cells.

Molecular imaging of peroxynitrite with HKGreen-4 in live cells and tissues.

Peroxynitrite (ONOO(-)), the product of a radical combination reaction of nitric oxide and superoxide, is a potent biological oxidant involved in a broad spectrum of physiological and pathological processes. Herein we report the development, characterization, and biological applications of a new fluorescent probe, HKGreen-4, for peroxynitrite detection and imaging. HKGreen-4 utilizes a peroxynitrite-triggered oxidative N-dearylation reaction to achieve an exceptionally sensitive and selective fluorescence turn-on response toward peroxynitrite in chemical systems and biological samples.

HKOCl-2 series of green BODIPY-based fluorescent probes for hypochlorous acid detection and imaging in live cells.

A HKOCl-2 series of new fluorescent probes for hypochlorous acid (HOCl) detection in live cells is reported. The probes exhibit excellent selectivity, sensitivity, and chemostability toward HOCl. In particular, HKOCl-2b rapidly and selectively detects endogenous HOCl in both human and mouse macrophages.