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Bovine milk exosomes (BMEs) are being explored in drug delivery despite their rapid elimination by macrophages. We aimed at identifying the BME transporter in murine bone marrow-derived macrophages (BMDMs). Fluorophore-labeled BMEs were used in transport studies in BMDMs from C57BL/6J and class A scavenger receptor type 1/2 (CASR-1/2) knockout mice and tissue accumulation in macrophage-depleted C57BL/6J mice. Parametric and nonparametric statistics tests for pairwise and multiple comparisons were used. Chemical inhibitors of phagocytosis by cytochalasin D led to a 69 ± 18% decrease in BME uptake compared with controls ( P < 0.05), whereas inhibitors of endocytic pathways other than phagocytosis had a modest effect on uptake ( P > 0.05). Inhibitors of class A scavenger receptors (CASRs) including CASR-1/2 caused a 70% decrease in BME uptake ( P < 0.05). The uptake of BMEs by BMDMs from CASR-1/2 knockout mice was smaller by 58 ± 23% compared with wild-type controls ( P < 0.05). Macrophage depletion by clodronate caused a more than 44% decrease in BME uptake in the spleen and lungs ( P < 0.05), whereas the decrease observed in liver was not statistically significant. In conclusion, CASR-1/2 facilitates the uptake of BMEs in BMDMs and C57BL/6J mice.

The nucleotide-binding domain and leucine-rich repeat-containing family, pyrin domain-containing 3 (NLRP3) inflammasome is a key regulator of innate immune responses, and its aberrant activation is implicated in the pathogenesis of many diseases such as Alzheimer's disease and type 2 diabetes. Targeting the NLRP3 inflammasome could hold promise to combat these complex diseases, but therapies specifically inhibiting the NLRP3 inflammasome have not been developed for patient treatment. The current study aimed to identify food-borne exosome-like nanoparticles (ELNs) that inhibit NLRP3 inflammasome activity. Nine vegetables or fruits were selected to extract ELNs, which were examined for their inhibitory effects on activation of the NLRP3 inflammasome in primary macrophages. Although most of the tested ELNs posed minimal impacts, the ELNs from ginger rhizomes (G-ELNs) strongly inhibited NLRP3 inflammasome activation. The G-ELNs contained lipids, proteins, and RNAs and were easily taken up by macrophages. G-ELN treatment suppressed pathways downstream of inflammasome activation including caspase1 autocleavage, interleukin (IL)-1β and IL-18 secretion, and pyroptotic cell death. Apoptotic speck protein containing a caspase recruitment domain (ASC) oligomerization and speck formation assays indicated that G-ELNs blocked assembly of the NLRP3 inflammasome. The lipids in G-ELNs, rather than the RNAs or proteins, were responsible for the inhibitory activity observed. Together, the data suggested G-ELNs as new potent agents that block NLRP3 inflammasome assembly and activation. The unique features of G-ELNs including biomolecule protection and tissue bioavailability should facilitate the development of G-ELN-based therapy to target the NLRP3 inflammasome in the disease settings.

OBJECTIVES: Bovine milk exosomes (BMEs) are promising candidates for delivering drugs to brain tumors because they are scalable, bioavailable after oral administration, and cross the blood-brain barrier. The use of BMEs in drug delivery is limited by their rapid elimination by macrophages. The objectives of this study were to identify the BME transporter and assess BME transport kinetics in murine bone marrow-derived macrophages (BMDMs) as a first step toward developing strategies that decrease the elimination of drug-loaded BMEs. METHODS: BMEs were isolated by differential centrifugation from skim milk. For transport studies, proteins and lipids on the BME surface were labeled with HiLyte™ Fluor 750 hydrazide and PKH26, respectively, and RNAs in BMEs were labeled with Exo-Red; unlabeled BMEs were used to assess background noise. Bone marrow cells were isolated from the femur and tibia of both C57BL/6J and scavenger receptor A-I/II knockout mice and differentiated ex vivo into BMDMs for use in transport studies. ANOVA, Dunnett's and Kruskal-Wallis test, Dunn's post-hoc test, unpaired t-test, and two-tailed Mann–Whitney U tests were used for statistical analysis; P 0.05). Treatment with inhibitors of class A scavenger receptor (CASR), fucoidan and dextran sulfate caused a 70 ± 8.1% and 70 ± 18% decrease (P ˂ 0.05), respectively, in BME uptake. The role of CASR in BME uptake was confirmed by using a genetics approach: the uptake of BMEs by BMDMs from scavenger receptor A-I/II knockout mice decreased by 58 ± 23% compared to BMDMs from wild-type mice (P ˂ 0.05). CONCLUSIONS: BME uptake is facilitated by CASR in BMDMs and uptake cannot be saturated under physiological conditions. FUNDING SOURCES: NIH 1P20GM104320, and NIFA 2016–67,001-25,301 and 2020–67,017-30,834, USDA Hatch-1,011,996, and USDA W4002 (all to J.Z.). J.Z is a consultant for PureTech Health, Inc.

Honey has been used as a nutrient, an ointment, and a medicine worldwide for many centuries. Modern research has demonstrated that honey has many medicinal properties, reflected in its anti‐microbial, anti‐oxidant, and anti‐inflammatory bioactivities. Honey is composed of sugars, water and a myriad of minor components, including minerals, vitamins, proteins and polyphenols. Here, we report a new bioactive component‒vesicle‐like nanoparticles‒in honey (H‐VLNs). These H‐VLNs are membrane‐bound nano‐scale particles that contain lipids, proteins and small‐sized RNAs. The presence of plant‐originated plasma transmembrane proteins and plasma membrane‐associated proteins suggests the potential vesicle‐like nature of these particles. H‐VLNs impede the formation and activation of the nucleotide‐binding domain and leucine‐rich repeat related (NLR) family, pyrin domain containing 3 (NLRP3) inflammasome, which is a crucial inflammatory signalling platform in the innate immune system. Intraperitoneal administration of H‐VLNs in mice alleviates inflammation and liver damage in the experimentally induced acute liver injury. miR‐4057 in H‐VLNs was identified in inhibiting NLRP3 inflammasome activation. Together, our studies have identified anti‐inflammatory VLNs as a new bioactive agent in honey.

Arsenic, a naturally occurring metalloid derived from the environment, has been studied worldwide for its causative effects in various cancers. However, the effects of arsenic toxicity on the development and progression of metabolic syndrome, including obesity and diabetes, has received less attention. Many studies suggest that metabolic dysfunction and autophagy dysregulation of adipose and muscle tissues are closely related to the development of metabolic disease. In the USA, arsenic contamination has been reported in some ground water, soil and grain samples in major agricultural regions, but the effects on adipose and muscle tissue metabolism and autophagy have not been investigated much. Here, we highlight arsenic toxicity according to the species, dose and exposure time and the effects on adipose and muscle tissue metabolism and autophagy. Historically, arsenic was used as both a poison and medicine, depending on the dose and treatment time. In the modern era, arsenic intoxication has significantly increased due to exposure from water, soil and food, which could be a contributing factor in the development and progression of metabolic disease. From this review, a better understanding of the pathogenic mechanisms by which arsenic alters metabolism and autophagy regulation could become a cornerstone leading to the development of therapeutic strategies against arsenic-induced toxicity and metabolic disease.

Majority of disease-modifying therapeutic targets are restricted to the intracellular space and are therefore not druggable using existing biologic modalities. The ability to efficiently deliver macromolecules inside target cells or tissues would greatly expand the current landscape of therapeutic targets for future generations of biologic drugs, but remains challenging. Here we report the use of extracellular vesicles, known as arrestin domain containing protein 1 [ARRDC1]-mediated microvesicles (ARMMs), for packaging and intracellular delivery of a myriad of macromolecules, including the tumor suppressor p53 protein, RNAs, and the genome-editing CRISPR-Cas9/guide RNA complex. We demonstrate selective recruitment of these macromolecules into ARMMs. When delivered intracellularly via ARMMs, these macromolecules are biologically active in recipient cells. P53 delivered via ARMMs induces DNA damage-dependent apoptosis in multiple tissues in mice. Together, our results provide proof-of-principle demonstration that ARMMs represent a highly versatile platform for packaging and intracellular delivery of therapeutic macromolecules., One of the challenges of biologic drug therapy is delivery into target cells and tissues. Here the authors present ARMMs (arrestin domain containing protein 1 mediated microvesicles) as a versatile platform for packaging and delivery of a myriad of molecules, including p53, RNAs and CRISPR-Cas9.

OBJECTIVES: The NLRP3 inflammasome is a key regulator of innate immune responses, and its aberrant activation has been implicated in the pathogenesis of many complex diseases including multiple sclerosis, type 2 diabetes and atherosclerosis. Our study aimed to identify the food-borne exosome-like nanoparticles (ELNs) that inhibit NLRP3 inflammasome in macrophages. METHODS: ELNs from nine vegetables or fruits were purified using ultracentrifugation, incubated with bone-marrow derived macrophages, followed by the activation of NLRP3 inflammasome. After the dietary ELNs with strong inhibitory effects on inflammasome were identified, their roles in the inflammasome assembly and downstream pathways were further examined. RESULTS: We identified that ELNs from ginger rhizomes (G-ELNs) strongly inhibited NLRP3 inflammasome activation. We verified that G-ELNs were exosome-like nanoparticles containing biomolecules including RNAs, proteins, and lipids. The G-ELNs were taken up by macrophages. G-ELNs suppressed the downstream pathways of NLRP3 inflammasome activation including Casp1 auto-cleavage, interleukin (IL)-1 and IL-18 secretion, and pyroptotic cell death. G-ELNs blocked the assembling steps of NLRP3 inflammasome, but had no effects on protein levels of a key mediator of NLRP3 inflammasome NIMA-related kinase 7 (Nek7), or the inflammasome subunits NLRP3, ASC, and Casp1. CONCLUSIONS: Our findings identified G-ELNs as a new potent agent that blocks NLRP3 inflammasome assembly and activation. FUNDING SOURCES: This work was supported by the National Institutes of Health (NIH) 1P20GM104320 Nebraska Center Prevention of Obesity Diseases (NPOD) Seed Grant and Project Leader Grant, and the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) Hatch Project 1015948.

Macrophage activation/polarization to distinct functional states is critically supported by metabolic shifts. How polarizing signals coordinate metabolic and functional reprogramming, and the potential implications for control of macrophage activation, remains poorly understood. Here we show that IL-4 signaling co-opts the Akt-mTORC1 pathway to regulate Acly, a key enzyme in Ac-CoA synthesis, leading to increased histone acetylation and M2 gene induction. Only a subset of M2 genes is controlled in this way, including those regulating cellular proliferation and chemokine production. Moreover, metabolic signals impinge on the Akt-mTORC1 axis for such control of M2 activation. We propose that Akt-mTORC1 signaling calibrates metabolic state to energetically demanding aspects of M2 activation, which may define a new role for metabolism in supporting macrophage activation.

The acetylation of histone tails is a primary determinant of gene activity. Histone deacetylase 3 (HDAC3) requires the nuclear receptor corepressor SMRT for HDAC enzyme activity. Here we report that HDAC3 interacts with SMRT only after priming by cellular chaperones including the TCP-1 ring complex (TRiC), which is required for proper folding of HDAC3 in an ATP-dependent process. SMRT displaces TRiC from HDAC3, yielding an active HDAC enzyme. The SMRT–HDAC3 repression complex thus joins the VHL–elongin BC tumor suppression complex and the cyclin E–Cdk2 cell cycle regulation complex as critical cellular machines requiring TRiC for proper assembly and function. The strict control of HDAC3 activity underscores the cellular imperative that histone deacetylation occur only in targeted regions of the genome.

Inflammasomes are intracellular sensors that couple detection of pathogens and cellular stress to activation of Caspase-1, and consequent IL-1β and IL-18 maturation and pyroptotic cell death. Here, we show that the absent in melanoma 2 (AIM2) and nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes trigger Caspase-1-dependent mitochondrial damage. Caspase-1 activates multiple pathways to precipitate mitochondrial disassembly, resulting in mitochondrial reactive oxygen species (ROS) production, dissipation of mitochondrial membrane potential, mitochondrial permeabilization, and fragmentation of the mitochondrial network. Moreover, Caspase-1 inhibits mitophagy to amplify mitochondrial damage, mediated in part by cleavage of the key mitophagy regulator Parkin. In the absence of Parkin activity, increased mitochondrial damage augments pyroptosis, as indicated by enhanced plasma membrane permeabilization and release of danger-associated molecular patterns (DAMPs). Therefore, like other initiator caspases, Caspase-1 activation by inflammasomes results in mitochondrial damage.

A chlL-deletion mutant of Synechocystis sp. PCC 6803 designated as chlL- was unable to make significant amounts of chlorophyll in darkness. However, an apparent pseudorevertant has been generated spontaneously that can synthesize an increased amount of chlorophyll under light-activated heterotrophic growth conditions. Under these conditions, the chlorophyll content in this pseudorevertant was about 20% of that in the wild-type strain and about 4 times more than that in the original and in the recently recreated chlL-deletion mutant. This is paralleled by increased performance of dark-grown cells in terms of chlorophyll fluorescence induction and oxygen evolution rates in the pseudorevertant versus in the original mutant. PCR analysis confirmed that the chlL- -pseudorevertant mutant still lacked the chlL gene. These results imply that the light-independent chlorophyll biosynthesis pathway was partly recovered.

Inactivation of the chlL gene in Synechocystis sp. PCC 6803 resulted in negligible chlorophyll content when the mutant was grown in darkness. Upon phycocyanin excitation at 580 nm, the 77K fluorescence spectrum of dark-grown cells showed three peaks at 648 nm, 665 nm, and 685 nm, this last being the largest. This reflects the functional presence of major components of phycobilisomes, including phycocyanin, allophycocyanin, and the terminal emitter, and efficient energy transfer between these components. As expected, no fluorescence emission peaks corresponding to chlorophyll in the photosystems were observed. Intact phycobilisomes could be isolated from the dark-grown chlL-deletion mutant. However, the phycobilisomes had a lower efficiency of energy transfer than did those isolated from the light-grown mutant, probably because of a decreased phycobilisome stability in the absence of chlorophyll. Exposing the dark-grown chlL-deletion mutant to light triggered the biosynthesis of chlorophyll. For the first 6 h in the light, upon phycocyanin excitation at 580 nm, the 77K fluorescence emission spectrum of greening cells was identical to that of dark-grown cells that lacked significant amounts of chlorophyll. With increased chlorophyll synthesis, gradual energy transfer from phycobilisomes to the two photosystems can be demonstrated.

The NLRP3 (nucleotide-binding domain, leucine-rich-repeat-containing family, pyrin domain-containing 3) inflammasome mediates production of inflammatory mediators, such as IL-1β and IL-18, and as such is implicated in a variety of inflammatory processes, including infection, sepsis, autoinflammatory diseases, and metabolic diseases. The proximal steps in NLRP3 inflammasome activation are not well understood. Here we elucidate a critical role for Ca 2+ mobilization in activation of the NLRP3 inflammasome by multiple stimuli. We demonstrate that blocking Ca 2+ mobilization inhibits assembly and activation of the NLRP3 inflammasome complex, and that during ATP stimulation Ca 2+ signaling is pivotal in promoting mitochondrial damage. C/EPB homologous protein, a transcription factor that can modulate Ca 2+ release from the endoplasmic reticulum, amplifies NLRP3 inflammasome activation, thus linking endoplasmic reticulum stress to activation of the NLRP3 inflammasome. Our findings support a model for NLRP3 inflammasome activation by Ca 2+ -mediated mitochondrial damage.

Ligands for nuclear receptors facilitate the exchange of co-repressors for coactivators, leading to chromatin modifications that favour the activation of gene transcription. Here, we show that the repressed state of an endogenous retinoic acid-regulated gene is quickly re-established after ligand removal. As expected, repression is characterized by recruitment of N-CoR/SMRT–HDAC3 (histone deacetylase 3) co-repressor complexes, leading to local histone hypoacetylation. The achievement of the repressed state involves the ordered deacetylation of lysines in H4 tails. This order is determined by the inherent substrate specificity of HDAC3, and unexpectedly predicts the binding preference of N-CoR/SMRT for submaximally acetylated H4 tails. The match between the specificity of acetyl-histone deacetylation by HDAC3 and the histone-binding preference of N-CoR/SMRT allows the co-repressor complex to stabilize and propagate repression of nuclear hormone receptor gene targets.

The identities of signal transducer proteins that integrate histone hypoacetylation and transcriptional repression are largely unknown. Here we demonstrate that THAP7, an uncharacterized member of the recently identified THAP (Thanatos-associated protein) family of proteins, is ubiquitously expressed, associates with chromatin, and represses transcription. THAP7 binds preferentially to hypoacetylated (un-, mono-, and diacetylated) histone H4 tails in vitro via its C-terminal 77 amino acids. Deletion of this domain, or treatment of cells with the histone deacetylase inhibitor TSA, which leads to histone hyperacetylation, partially disrupts THAP7/chromatin association in living cells. THAP7 coimmunoprecipitates with histone deacetylase 3 (HDAC3) and the nuclear hormone receptor corepressor (NCoR) and represses transcription as a Gal4 fusion protein. Chromatin immunoprecipitation assays demonstrate that these corepressors are recruited to promoters in a THAP7 dependent manner and promote histone H3 hypoacetylation. The conserved THAP domain is a key determinant for full HDAC3 association in vitro, and both the THAP domain and the histone interaction domain are important for the repressive properties of THAP7. Full repression mediated by THAP7 is also dependent on NCoR expression. We hypothesize that THAP7 is a dual function repressor protein that actively targets deacetylation of histone H3 necessary to establish transcriptional repression and functions as a signal transducer of the repressive mark of hypoacetylated histone H4. This is the first demonstration of the transcriptional regulatory properties of a human THAP domain protein, and a critical identification of a potential transducer of the repressive signal of hypoacetylated histone H4 in higher eukaryotes.