Type 2 inflammation is associated with epithelial cell responses, including goblet cell hyperplasia, that promote worm expulsion during intestinal helminth infection. How these epithelial responses are regulated remains incompletely understood. Here, we show that mice deficient in the prostaglandin D2 (PGD2) receptor CRTH2 and mice with CRTH2 deficiency only in nonhematopoietic cells exhibited enhanced worm clearance and intestinal goblet cell hyperplasia following infection with the helminth Nippostrongylus brasiliensis. Small intestinal stem, goblet, and tuft cells expressed CRTH2. CRTH2-deficient small intestinal organoids showed enhanced budding and terminal differentiation to the goblet cell lineage. During helminth infection or in organoids, PGD2 and CRTH2 down-regulated intestinal epithelial Il13ra1 expression and reversed Type 2 cytokine–mediated suppression of epithelial cell proliferation and promotion of goblet cell accumulation. These data show that the PGD2–CRTH2 pathway negatively regulates the Type 2 cytokine–driven epithelial program, revealing a mechanism that can temper the highly inflammatory effects of the anti-helminth response.

Hydrogen sulfide (H₂S) is a noxious, potentially poisonous, but necessary gas produced from sulfur metabolism in humans. In Down Syndrome (DS), the production of H₂S is elevated and associated with degraded mitochondrial function. Therefore, removing H₂S from the body as a stable oxide could be an approach to reducing the deleterious effects of H₂S in DS. In this report we describe the catalytic oxidation of hydrogen sulfide (H₂S) to polysulfides (HS_2+n⁻) and thiosulfate (S₂O₃²⁻) by poly(ethylene glycol) hydrophilic carbon clusters (PEG‐HCCs) and poly(ethylene glycol) oxidized activated charcoal (PEG‐OACs), examples of oxidized carbon nanozymes (OCNs). We show that OCNs oxidize H₂S to polysulfides and S₂O₃²⁻ in a dose‐dependent manner. The reaction is dependent on O₂ and the presence of quinone groups on the OCNs. In DS donor lymphocytes we found that OCNs increased polysulfide production, proliferation, and afforded protection against additional toxic levels of H₂S compared to untreated DS lymphocytes. Finally, in Dp16 and Ts65DN murine models of DS, we found that OCNs restored osteoclast differentiation. This new action suggests potential facile translation into the clinic for conditions involving excess H₂S exemplified by DS.

Pro‐energetic effects of functionalized, oxidized carbon nanozymes (OCNs) are reported. OCNs, derived from harsh acid oxidation of single‐wall carbon nanotubes or activated charcoal are previously shown to possess multiple nanozymatic activities including mimicking superoxide dismutase and catalyzing the oxidation of reduced nicotinamide adenine dinucleotide (NADH) to NAD ⁺ . These actions are predicted to generate a glycolytic shift and enhance mitochondrial energetics under impaired conditions. Impaired mitochondrial energy metabolism is increasingly recognized as an important facet of traumatic brain injury (TBI) pathophysiology and decreases the efficiency of electron transport chain (ETC)‐coupled adenosine triphosphate (ATP) and NAD ⁺ regeneration. In vitro, OCNs promote a pro‐aerobic shift in energy metabolism that persists through ETC inhibition and enhances glycolytic flux, glycolytic ATP production, and cellular generation of lactate, a crucial auxiliary substrate for energy metabolism. To address specific mechanisms of iron injury from hemorrhage, OCNs with the iron chelator, deferoxamine (DEF), covalently‐linked were synthesized. DEF‐linked OCNs induce a glycolytic shift in‐vitro and in‐vivo in tissue sections from a rat model of TBI complicated by hemorrhagic contusion. OCNs further reduced hemorrhage volumes 3 days following TBI. These results suggest OCNs are promising as pleiotropic mediators of cell and tissue resilience to injury.

Down syndrome (DS) is a multisystemic disorder that includes accelerated aging caused by trisomy 21. In particular, overexpression of cystathionine-β-synthase (CBS) is linked to excess intracellular hydrogen sulfide (H₂S), a mitochondrial toxin at higher concentrations, which impairs cellular viability. Concurrent overexpression of superoxide dismutase 1 (SOD1) may increase oxidative stress by generating excess hydrogen peroxide (H₂O₂) while also mitigating the toxic H₂S burden via a non-canonical sulfide-oxidizing mechanism. We investigated the phenotypic variability in basal H₂S levels in relation to DS B lymphocyte cell health and SOD1 in H₂S detoxification. The H₂S levels were negatively correlated with the DS B lymphocyte growth rates but not with CBS protein. Pharmacological inhibition of SOD1 using LCS-1 significantly increased the H₂S levels to a greater extent in DS cells while also decreasing the polysulfide products of H₂S oxidation. However, DS cells exhibited elevated H₂O₂ and lipid peroxidation, representing potential toxic consequences of SOD1 overexpression. Treatment of DS cells with a pleiotropic carbon nanozyme (pleozymes) decreased the total oxidative stress and reduced the levels of the H₂S-generating enzymes CBS and 3-mercaptopyruvate sulfurtransferase (MPST). Our results indicate that pleozymes may bridge the protective and deleterious effects of DS SOD1 overexpression on H₂S metabolism and oxidative stress, respectively, with cytoprotective benefits.

Harsh acid oxidation of activated charcoal transforms an insoluble carbon-rich source into water-soluble, disc structures of graphene decorated with multiple oxygen-containing functionalities. We term these pleiotropic nano-enzymes as “pleozymes”. A broad redox potential spans many crucial redox reactions including the oxidation of hydrogen sulfide (H₂S) to polysulfides and thiosulfate, dismutation of the superoxide radical (O₂⁻*), and oxidation of NADH to NAD⁺. The oxidation of H₂S is predicted to enhance protein persulfidation—the attachment of sulfur to cysteine residues. Persulfidated proteins act as redox intermediates, and persulfidation protects proteins from irreversible oxidation and ubiquitination, providing an important means of signaling. Protein persulfidation is believed to decline in several neurological disorders and aging. Importantly, and consistent with the role of persulfidation in signaling, the master antioxidant transcription factor Nrf2 is regulated by Keap1’s persulfidation. Here, we demonstrate that pleozymes increased overall protein persulfidation in cells from apparently healthy individuals and from individuals with the mitochondrial protein mutation responsible for Friedreich’s ataxia. We further find that pleozymes specifically enhanced Keap1 persulfidation, with subsequent increased accumulation of Nrf2 and Nrf2’s antioxidant targets.

Our group has synthesized a pleiotropic synthetic nanozyme redox mediator we term a “pleozyme” that displays multiple enzymatic characteristics, including acting as a superoxide dismutase mimetic, oxidizing NADH to NAD⁺, and oxidizing H₂S to polysulfides and thiosulfate. Benefits have been seen in acute and chronic neurological disease models. The molecule is sourced from coconut-derived activated charcoal that has undergone harsh oxidization with fuming nitric acid, which alters the structure and chemical characteristics, yielding 3–8 nm discs with broad redox potential. Prior work showed pleozymes localize to mitochondria and increase oxidative phosphorylation and glycolysis. Here, we measured cellular NAD⁺ and NADH levels after pleozyme treatment and observed increased total cellular NADH levels but not total NAD⁺ levels. A ¹³C-glucose metabolic flux analysis suggested pleozymes stimulate the generation of pyruvate and lactate glycolytically and from the tricarboxylic acid (TCA) cycle, pointing to malate decarboxylation. Analysis of intracellular fatty acid abundances suggests pleozymes increased fatty acid β-oxidation, with a concomitant increase in succinyl- and acetyl-CoA. Pleozymes increased total ATP, potentially via flexible enhancement of NAD⁺-dependent catabolic pathways such as glycolysis, fatty acid β-oxidation, and metabolic flux through the TCA cycle. These effects may be favorable for pathologies that compromise metabolism such as brain injury.