Tobacco Alkaloid Assessment in a DSS-Induced Colitis Mouse Model with a Fully Humanized Immune System.

Inflammatory bowel disease (IBD) refers to chronic intestinal immune-mediated diseases including two main disease manifestations: ulcerative colitis (UC) and Crohn's disease (CD). Epidemiological, clinical, and preclinical evidence has highlighted the potential anti-inflammatory properties of naturally occurring alkaloids. In the present study, we investigated the potential anti-inflammatory activities of the tobacco alkaloids nicotine and anatabine in a dextran sulfate sodium (DSS)-induced UC mouse model with a fully humanized immune system. Our results show that nicotine significantly reduced all acute colitis symptoms and improved colitis-specific endpoints, including histopathologically assessed colon inflammation, tissue damage, and mononuclear cell infiltration. The tobacco alkaloid anatabine showed similar effectiveness trends, although they were generally weaker or not significant. Gene expression analysis in the context of biological network models of IBD further pinpointed a possible mechanism by which nicotine attenuated DSS-induced colitis in humanized mice. The current study enables further investigation of possible molecular mechanisms by which tobacco alkaloids attenuate UC symptoms.

Proteomics and Lipidomics in Inflammatory Bowel Disease Research: From Mechanistic Insights to Biomarker Identification.

Inflammatory bowel disease (IBD) represents a group of progressive disorders characterized by recurrent chronic inflammation of the gut. Ulcerative colitis and Crohn's disease are the major manifestations of IBD. While our understanding of IBD has progressed in recent years, its etiology is far from being fully understood, resulting in suboptimal treatment options. Complementing other biological endpoints, bioanalytical "omics" methods that quantify many biomolecules simultaneously have great potential in the dissection of the complex pathogenesis of IBD. In this review, we focus on the rapidly evolving proteomics and lipidomics technologies and their broad applicability to IBD studies; these range from investigations of immune-regulatory mechanisms and biomarker discovery to studies dissecting host⁻microbiome interactions and the role of intestinal epithelial cells. Future studies can leverage recent advances, including improved analytical methodologies, additional relevant sample types, and integrative multi-omics analyses. Proteomics and lipidomics could effectively accelerate the development of novel targeted treatments and the discovery of complementary biomarkers, enabling continuous monitoring of the treatment response of individual patients; this may allow further refinement of treatment and, ultimately, facilitate a personalized medicine approach to IBD.

The Apoe(-/-) mouse model: a suitable model to study cardiovascular and respiratory diseases in the context of cigarette smoke exposure and harm reduction.

Atherosclerosis-prone apolipoprotein E-deficient (Apoe(-/-)) mice display poor lipoprotein clearance with subsequent accumulation of cholesterol ester-enriched particles in the blood, which promote the development of atherosclerotic plaques. Therefore, the Apoe(-/-) mouse model is well established for the study of human atherosclerosis. The systemic proinflammatory status of Apoe(-/-) mice also makes them good candidates for studying chronic obstructive pulmonary disease, characterized by pulmonary inflammation, airway obstruction, and emphysema, and which shares several risk factors with cardiovascular diseases, including smoking. Herein, we review the results from published studies using Apoe(-/-) mice, with a particular focus on work conducted in the context of cigarette smoke inhalation studies. The findings from these studies highlight the suitability of this animal model for researching the effects of cigarette smoking on atherosclerosis and emphysema.

Effects of cigarette smoke, cessation and switching to a candidate modified risk tobacco product on the liver in Apoe -/- mice--a systems toxicology analysis.

The liver is one of the most important organs involved in elimination of xenobiotic and potentially toxic substances. Cigarette smoke (CS) contains more than 7000 chemicals, including those that exert biological effects and cause smoking-related diseases. Though CS is not directly hepatotoxic, a growing body of evidence suggests that it may exacerbate pre-existing chronic liver disease. In this study, we integrated toxicological endpoints with molecular measurements and computational analyses to investigate effects of exposures on the livers of Apoe(-/- )mice. Mice were exposed to 3R4F reference CS, to an aerosol from the Tobacco Heating System (THS) 2.2, a candidate modified risk tobacco product (MRTP) or to filtered air (Sham) for up to 8 months. THS2.2 takes advantage of a "heat-not-burn" technology that, by heating tobacco, avoids pyrogenesis and pyrosynthesis. After CS exposure for 2 months, some groups were either switched to the MRTP or filtered air. While no group showed clear signs of hepatotoxicity, integrative analysis of proteomics and transcriptomics data showed a CS-dependent impairment of specific biological networks. These networks included lipid and xenobiotic metabolism and iron homeostasis that likely contributed synergistically to exacerbating oxidative stress. In contrast, most proteomic and transcriptomic changes were lower in mice exposed to THS2.2 and in the cessation and switching groups compared to the CS group. Our findings elucidate the complex biological responses of the liver to CS exposure. Furthermore, they provide evidence that THS2.2 aerosol has reduced biological effects, as compared with CS, on the livers of Apoe(-/- )mice.

Neuron-derived orphan receptor 1 promotes proliferation of quiescent hepatocytes.

BACKGROUND & AIMS: Studies of the transcriptional networks that regulate nuclear receptor-mediated proliferation of quiescent hepatocytes could lead to new information about liver growth and hepatoprotective strategies. METHODS: We used quantitative real-time PCR to analyze expression of neuron-derived orphan receptor 1 (Nor-1) and its target genes during liver regeneration after hepatectomy in mice, and in hepatocellular carcinoma (HCC) samples from patients. We used adenoviral vectors to express Nor-1 in normal liver (Ad/CMV/V5-Nor-1), or reduce its level with small hairpin RNAs (Ad/BLOCK-iT/Nor-1(small hairpin RNA)) after partial hepatectomy. RESULTS: Levels of Nor-1 messenger RNA and protein, and transcription of Nor-1 target genes (Ccnd1 and Vcam-1), increased during the late priming and proliferative phases of liver regeneration after partial hepatectomy. Levels of NOR-1 messenger RNA and transcription of its target gene CCND1 and of the NOR-1 subfamily member NUR-77 also increased in human HCC samples compared with paired HCC-free tissue. Ad-Nor-1(small hairpin RNA) reduced the hepatocyte proliferation after hepatectomy. Overexpression of Nor-1 in normal livers of mice induced proliferation of quiescent hepatocytes independently of interleukin-6 and tumor necrosis factor-α signaling. In gene expression profile analysis, Nor-1 altered expression of genes involved in the cell cycle, proliferation, and tumorigenesis. CONCLUSIONS: In mice, the orphan nuclear receptor Nor-1 activates proliferation of quiescent hepatocytes and is required for hepatocyte proliferation after partial hepatectomy. Nor-1 and its gene targets are also up-regulated in human HCC samples. Nor-1 activates a transcriptional program that induces hepatocyte proliferation independently of inflammatory signaling pathways.

Liver X receptors inhibit proliferation of human colorectal cancer cells and growth of intestinal tumors in mice.

BACKGROUND & AIMS: Liver X receptors (LXRs) are transcriptional regulators of cholesterol metabolism, controlling cholesterol flow into cells, catabolism, and efflux. Cholesterol controls cell proliferation; disruptions in cholesterol metabolism have been associated with the development of colon cancer. We investigated whether expression of activated LXR protects against intestinal tumorigenesis in mice. METHODS: We analyzed the development of colon cancer in mice that express a constitutive active form of LXRα only in the intestinal epithelium, under the control of villin promoter (iVP16LXRα). These mice were crossed with adenomatous polyposis coli (Apc)(min/+) mice, or given azoxymethane followed by dextran sodium sulfate, to assess intestinal tumor formation. We also assessed proliferation and apoptosis of a human colorectal cancer cell line (HT29) transfected with an adenoviral vector that expressed Ad VP16hLXRα, compared with cells expressing AdVP16 (control), and their ability to form xenograft tumors in mice. HT29 cells also were incubated with the LXR ligand GW3965. RESULTS: In human colorectal cancer cells, ligand-induced activation of LXR or transfection with Ad VP16hLXRα blocked the G1 phase, increased caspase-dependent apoptosis, and slowed growth of xenograft tumors in mice. iVP16LXRα mice formed fewer, smaller tumors than VP16 (control) mice after administration of azoxymethane and dextran sodium sulfate. APC(min/+)/iVP16LXRα mice also developed fewer, smaller intestinal tumors than APC(min/+)/iVP16 mice. Gene expression analysis indicated that activation of LXRα affected lipid metabolic networks and increased cholesterol efflux in the intestine. CONCLUSIONS: Expression of activated LXRα blocks proliferation of human colorectal cancer cells and slows the growth of xenograft tumors in mice. It also reduces intestinal tumor formation after administration of chemical carcinogens, and in Apc(min/+) mice. LXR agonists therefore might be developed as therapeutic treatments for colorectal cancer.

Peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC1alpha) is a metabolic regulator of intestinal epithelial cell fate.

Peroxisome proliferator-activated receptor-γ coactivator 1-α (PGC1α) is a transcriptional coactivator able to up-regulate mitochondrial biogenesis, respiratory capacity, oxidative phosphorylation, and fatty acid ß-oxidation with the final aim of providing a more efficient pathway for aerobic energy production. In the continuously renewed intestinal epithelium, proliferative cells in the crypts migrate along the villus axis and differentiate into mature enterocytes, increasing their respiratory capacity and finally undergoing apoptosis. Here we show that in the intestinal epithelial surface, PGC1α drives mitochondrial biogenesis and respiration in the presence of reduced antioxidant enzyme activities, thus determining the accumulation of reactive oxygen species and fostering the fate of enterocytes toward apoptosis. Combining gain- and loss-of-function genetic approaches in human cells and mouse models of intestinal cancer, we present an intriguing scenario whereby PGC1α regulates enterocyte cell fate and protects against tumorigenesis.

Liver X receptor activation reduces angiogenesis by impairing lipid raft localization and signaling of vascular endothelial growth factor receptor-2.

OBJECTIVE: Liver X receptors (LXRα, LXRß) are master regulators of cholesterol homeostasis. In the endothelium, perturbations of cell cholesterol have an impact on fundamental processes. We, therefore, assessed the effects of LXR activation on endothelial functions related to angiogenesis in vitro and in vivo. METHODS AND RESULTS: LXR agonists (T0901317, GW3965) blunted migration, tubulogenesis, and proliferation of human umbilical vein endothelial cells. By affecting endothelial cholesterol homeostasis, LXR activation impaired the compartmentation of vascular endothelial growth factor receptor-2 in lipid rafts/caveolae and led to defective phosphorylation and downstream signaling of vascular endothelial growth factor receptor-2 upon vascular endothelial growth factor-A stimulation. Consistently, the antiangiogenic actions of LXR agonists could be prevented by coadministration of exogenous cholesterol. LXR agonists reduced endothelial sprouting from wild-type but not from LXRα(-/-)/LXRß(-/-) knockout aortas and blunted the vascularization of implanted angioreactors in vivo. Furthermore, T0901317 reduced the growth of Lewis lung carcinoma grafts in mice by impairing angiogenesis. CONCLUSIONS: Pharmacological activation of endothelial LXRs reduces angiogenesis by restraining cholesterol-dependent vascular endothelial growth factor receptor-2 compartmentation and signaling. Thus, administration of LXR agonists could exert therapeutic effects in pathological conditions characterized by uncontrolled angiogenesis.

Results and lessons learned from the sbv IMPROVER metagenomics diagnostics for inflammatory bowel disease challenge.

A growing body of evidence links gut microbiota changes with inflammatory bowel disease (IBD), raising the potential benefit of exploiting metagenomics data for non-invasive IBD diagnostics. The sbv IMPROVER metagenomics diagnosis for inflammatory bowel disease challenge investigated computational metagenomics methods for discriminating IBD and nonIBD subjects. Participants in this challenge were given independent training and test metagenomics data from IBD and nonIBD subjects, which could be wither either raw read data (sub-challenge 1, SC1) or processed Taxonomy- and Function-based profiles (sub-challenge 2, SC2). A total of 81 anonymized submissions were received between September 2019 and March 2020. Most participants' predictions performed better than random predictions in classifying IBD versus nonIBD, Ulcerative Colitis (UC) versus nonIBD, and Crohn's Disease (CD) versus nonIBD. However, discrimination between UC and CD remains challenging, with the classification quality similar to the set of random predictions. We analyzed the class prediction accuracy, the metagenomics features by the teams, and computational methods used. These results will be openly shared with the scientific community to help advance IBD research and illustrate the application of a range of computational methodologies for effective metagenomic classification.

REV-ERBalpha participates in circadian SREBP signaling and bile acid homeostasis.

In mammals, many aspects of behavior and physiology, and in particular cellular metabolism, are coordinated by the circadian timing system. Molecular clocks are thought to rely on negative feedback loops in clock gene expression that engender oscillations in the accumulation of transcriptional regulatory proteins, such as the orphan receptor REV-ERBalpha. Circadian transcription factors then drive daily rhythms in the expression of clock-controlled output genes, for example genes encoding enzymes and regulators of cellular metabolism. To gain insight into clock output functions of REV-ERBalpha, we carried out genome-wide transcriptome profiling experiments with liver RNA from wild-type mice, Rev-erbalpha knock-out mice, or REV-ERBalpha overexpressing mice. On the basis of these genetic loss- and gain-of-function experiments, we concluded that REV-ERBalpha participates in the circadian modulation of sterol regulatory element-binding protein (SREBP) activity, and thereby in the daily expression of SREBP target genes involved in cholesterol and lipid metabolism. This control is exerted via the cyclic transcription of Insig2, encoding a trans-membrane protein that sequesters SREBP proteins to the endoplasmic reticulum membranes and thereby interferes with the proteolytic activation of SREBPs in Golgi membranes. REV-ERBalpha also participates in the cyclic expression of cholesterol-7alpha-hydroxylase (CYP7A1), the rate-limiting enzyme in converting cholesterol to bile acids. Our findings suggest that this control acts via the stimulation of LXR nuclear receptors by cyclically produced oxysterols. In conclusion, our study suggests that rhythmic cholesterol and bile acid metabolism is not just driven by alternating feeding-fasting cycles, but also by REV-ERBalpha, a component of the circadian clockwork circuitry.

Down-regulation of the LXR transcriptome provides the requisite cholesterol levels to proliferating hepatocytes.

Cholesterol homeostasis is critical for cellular proliferation. Liver X receptor (LXR) alpha and beta are the nuclear receptors responsible for regulation of cholesterol metabolism. In physiological conditions, high intracellular cholesterol levels cause increased synthesis of oxysterols, which activate LXR, thus triggering a transcriptional response for cholesterol secretion and catabolism. Here we employed a mouse model of partial hepatectomy (PH) to dissect the molecular pathways connecting cholesterol homeostasis, cellular proliferation, and LXR. First, we show that hepatic cholesterol content increases after PH, whereas the entire LXR transcriptome is down-regulated. Although LXR messenger RNA (mRNA) levels are unmodified, LXR target genes are significantly down-regulated on day 1 after PH and restored to control levels on day 7, when the liver reaches normal size. The inactivation of LXR following PH is related to the reduced oxysterol availability by way of decreased synthesis, and increased sulfation and secretion. On the contrary, cholesterol synthesis is up-regulated, and extracellular matrix remodeling is enhanced. Second, we show that reactivation of LXR by way of a synthetic ligand determines a negative modulation of hepatocyte proliferation. This effect is sustained by the reactivation of hepatic cholesterol catabolic and secretory pathways, coupled with a significant reduction of cholesterol biosynthesis. Our data unveil a previously unrecognized and apparently paradoxical scenario of LXR modulation. During liver regeneration LXR activity is abated in spite of increasing intracellular cholesterol levels. Turning off LXR-transcriptional pathways is crucial to guaranteeing the requisite intracellular cholesterol levels of regenerating hepatocytes. In line with this hypothesis, pharmacological LXR reactivation during PH significantly reduces liver regeneration capacity.

Development of an Advanced Multicellular Intestinal Model for Assessing Immunomodulatory Properties of Anti-Inflammatory Compounds.

Intestinal inflammation is the collective term for immune system-mediated diseases of unknown, multifactorial etiology, with often complex interactions between genetic and environmental factors. To mechanistically investigate the effect of treatment with compounds possessing immunomodulating properties in the context of intestinal inflammation, we developed an immunocompetent in vitro triculture intestinal model consisting of a differentiated intestinal epithelial layer (Caco-2/HT29-MTX) and immunocompetent cells (differentiated THP-1). The triculture mimicked a healthy intestine with stable barrier integrity. Lipopolysaccharide treatment triggered a controlled and reversible inflammatory state, resulting in significant impairment of barrier integrity and release of pro-inflammatory cytokines and chemokines, which are known hallmarks of intestinal inflammation. Treatment with known anti-inflammatory reference compounds (TPCA-1 and budenoside) prevented the induction of an inflammatory state; the decreasing triculture responses to this treatment measured by cytokine release, transepithelial electric resistance (TEER), and epithelial layer permeability proved the suitability of the intestinal model for anti-inflammatory drug screening. Finally, selected tobacco alkaloids (nicotine and anatabine (R/S and S forms)) were tested in the in vitro triculture for their potential anti-inflammatory properties. Indeed, naturally occurring alkaloids, such as tobacco-derived alkaloids, have shown substantial anti-inflammatory effects in several in vitro and in vivo models of inflammation, gaining increasing interest. Similar to the anti-inflammatory reference compounds, one of the tobacco alkaloids under investigation partially prevented the decrease in the TEER and increase in permeability and reduced the release of pro-inflammatory cytokines and chemokines. Taken together, these data confirm that our in vitro model is suitable for screening potential anti-inflammatory compounds in the context of intestinal inflammation.

Inflammatory Bowel Disease-Associated Changes in the Gut: Focus on Kazan Patients.

BACKGROUND: Several studies have highlighted the role of host-microbiome interactions in the pathogenesis of inflammatory bowel disease (IBD), resulting in an increasing amount of data mainly focusing on Western patients. Because of the increasing prevalence of IBD in newly industrialized countries such as those in Asia, the Middle East, and South America, there is mounting interest in elucidating the gut microbiota of these populations. We present a comprehensive analysis of several IBD-related biomarkers and gut microbiota profiles and functions of a unique population of patients with IBD and healthy patients from Kazan (Republic of Tatarstan, Russia). METHODS: Blood and fecal IBD biomarkers, serum cytokines, and fecal short-chain fatty acid (SCFA) content were profiled. Finally, fecal microbiota composition was analyzed by 16S and whole-genome shotgun sequencing. RESULTS: Fecal microbiota whole-genome sequencing confirmed the presence of classic IBD dysbiotic features at the phylum level, with increased abundance of Proteobacteria, Actinobacteria, and Fusobacteria and decreased abundance of Firmicutes, Bacteroidetes, and Verrucomicrobia. At the genus level, the abundance of both fermentative (SCFA-producing and hydrogen (H2)-releasing) and hydrogenotrophic (H2-consuming) microbes was affected in patients with IBD. This imbalance was confirmed by the decreased abundance of SCFA species in the feces of patients with IBD and the change in anaerobic index, which mirrors the redox status of the intestine. CONCLUSIONS: Our analyses highlighted how IBD-related dysbiotic microbiota-which are generally mainly linked to SCFA imbalance-may affect other important metabolic pathways, such as H2 metabolism, that are critical for host physiology and disease development.

An Intestine-on-a-Chip Model of Plug-and-Play Modularity to Study Inflammatory Processes.

Development of efficient drugs and therapies for the treatment of inflammatory conditions in the intestine is often hampered by the lack of reliable, robust, and high-throughput in vitro and in vivo models. Current models generally fail to recapitulate key aspects of the intestine, resulting in low translatability to the human situation. Here, an immunocompetent 3D perfused intestine-on-a-chip platform was developed and characterized for studying intestinal inflammation. Forty independent polarized 3D perfused epithelial tubular structures were grown from cells of mixed epithelial origin, including enterocytes (Caco-2) and goblet cells (HT29-MTX-E12). Immune cells THP-1 and MUTZ-3, which can be activated, were added to the system and assessed for cytokine release. Intestinal inflammation was mimicked through exposure to tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß. The effects were quantified by measuring transepithelial electrical resistance (TEER) and proinflammatory cytokine secretion on the apical and basal sides. Cytokines induced an inflammatory state in the culture, as demonstrated by the impaired barrier function and increased IL-8 secretion. Exposure to the known anti-inflammatory drug TPCA-1 prevented the inflammatory state. The model provides biological modularity for key aspects of intestinal inflammation, making use of well-established cell lines. This allows robust assays that can be tailored in complexity to serve all preclinical stages in the drug discovery and development process.

Anatabine ameliorates intestinal inflammation and reduces the production of pro-inflammatory factors in a dextran sulfate sodium mouse model of colitis.

BACKGROUND: Inflammatory bowel disease (IBD) is the collective term for chronic immune-mediated diseases of unknown, multifactorial etiology, arising from the interplay between genetic and environmental factors and including two main disease manifestations: ulcerative colitis (UC) and Crohn's disease. In the last few decades, naturally occurring alkaloids have gained interest because of their substantial anti-inflammatory effects in several animal models of disease. Studies on mouse models of IBD have demonstrated the anti-inflammatory action of the main tobacco alkaloid, nicotine. In addition, anatabine, a minor tobacco alkaloid also present in peppers, tomato, and eggplant presents anti-inflammatory properties in vivo and in vitro. In this study, we aimed to evaluate the anti-inflammatory properties of nicotine and anatabine in a dextran sulfate sodium (DSS) mouse model of UC. RESULTS: Oral administration of anatabine, but not nicotine, reduced the clinical symptoms of DSS-induced colitis. The result of gene expression analysis suggested that anatabine had a restorative effect on global DSS-induced gene expression profiles, while nicotine only had limited effects. Accordingly, MAP findings revealed that anatabine reduced the colonic abundance of DSS-associated cytokines and increased IL-10 abundance. CONCLUSIONS: Our results support the amelioration of inflammatory effects by anatabine in the DSS mouse model of UC, and suggest that anatabine constitutes a promising therapeutic agent for IBD treatment.

The reduction of DSS-induced colitis severity in mice exposed to cigarette smoke is linked to immune modulation and microbial shifts.

Exposure to cigarette smoke (CS) causes detrimental health effects, increasing the risk of cardiovascular, pulmonary diseases and carcinogenesis in exposed individuals. The impact of CS on Inflammatory Bowel Disease (IBD) has been established by a number of epidemiological and clinical studies. In fact, CS is associated with a higher risk of developing Crohn's disease (CD) while inversely correlates with the development, disease risks, and relapse rate of ulcerative colitis (UC). To investigate the effect of CS exposure on experimental colitis, we performed a comprehensive and integrated comparative analysis of colon transcriptome and microbiome in mice exposed to dextran sodium sulfate (DSS) and CS. Colon transcriptome analysis revealed that CS downregulated specific pathways in a concentration-dependent manner, affecting both the inflammatory state and composition of the gut microbiome. Metagenomics analysis demonstrated that CS can modulate DSS-induced dysbiosis of specific bacterial genera, contributing to resolve the inflammation or accelerate recovery. The risks of smoking far outweigh any possible benefit, thus smoking cessation must always be encouraged because of its significant health benefits. However, the inverse association between active smoking and the development of UC cannot be ignored and the present study lays the foundation for investigating potential molecular mechanisms responsible for the attenuation of colitis by certain compounds of tobacco when decoupled from combustion.

A translational view on the biliary lipid secretory network.

Bile formation springs from an extraordinary sophisticated secretory network, which combines the activity of transport proteins with the physico-chemical properties of small albeit powerful lipophilic compounds. This robust interplay is activated in response to dietary stimuli, circadian rhythms, and metabolic demands to regulate cholesterol disposal, lipid digestion and absorption in the enterohepatic system. As a result, bile flow is a complex multi-organ effort that requires an integrated flux of information between liver and intestine. A coordinate regulatory task is achieved by nuclear receptors, which are ligand activated transcription factors, responsible for the coherent activation of sets of genes involved in multiple physiological actions, including hepato-biliary homeostasis. Mastering the molecular pathways underlying functional and pharmacological modulation of bile flow has great translational value for potential future treatment of cholestasis and cholelithiasis. In this review, we focus on recent discoveries in the functional biology of bile formation with the explicit aim of underlining their putative clinical relevance.

Comparative systems toxicology analysis of cigarette smoke and aerosol from a candidate modified risk tobacco product in organotypic human gingival epithelial cultures: A 3-day repeated exposure study.

Smoking is one of the major lifestyle-related risk factors for periodontal diseases. Modified risk tobacco products (MRTP) offer a promising alternative in the harm reduction strategy for adult smokers unable to quit. Using a systems toxicology approach, we investigated and compared the exposure effects of a reference cigarette (3R4F) and a heat-not-burn technology-based candidate MRTP, the Tobacco Heating System (THS) 2.2. Human gingival epithelial organotypic cultures were repeatedly exposed (3 days) for 28 min at two matching concentrations of cigarette smoke (CS) or THS2.2 aerosol. Results showed only minor histopathological alterations and minimal cytotoxicity upon THS2.2 aerosol exposure compared to CS (1% for THS2.2 aerosol vs. 30% for CS, at the high concentration). Among the 14 proinflammatory mediators analyzed, only 5 exhibited significant alterations with THS2.2 exposure compared with 11 upon CS exposure. Transcriptomic and metabolomic analysis indicated a general reduction of the impact in THS2.2 aerosol-exposed samples with respect to CS (∼79% lower biological impact for the high THS2.2 aerosol concentration compared to CS, and 13 metabolites significantly perturbed for THS2.2 vs. 181 for CS). This study indicates that exposure to THS2.2 aerosol had a lower impact on the pathophysiology of human gingival organotypic cultures than CS.

Urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents.

The biological effects of urolithins remain poorly characterized, despite wide-spread human exposure via the dietary consumption of their metabolic precursors, the ellagitannins, which are found in the pomegranate fruit, as well as in nuts and berries. We identified urolithin A (UA) as a first-in-class natural compound that induces mitophagy both in vitro and in vivo following oral consumption. In C. elegans, UA prevented the accumulation of dysfunctional mitochondria with age and extended lifespan. Likewise, UA prolonged normal activity during aging in C. elegans, including mobility and pharyngeal pumping, while maintaining mitochondrial respiratory capacity. These effects translated to rodents, where UA improved exercise capacity in two different mouse models of age-related decline of muscle function, as well as in young rats. Our findings highlight the health benefits of urolithin A and its potential application in strategies to improve mitochondrial and muscle function.

Loss of Sirt1 function improves intestinal anti-bacterial defense and protects from colitis-induced colorectal cancer.

Dysfunction of Paneth and goblet cells in the intestine contributes to inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CAC). Here, we report a role for the NAD+-dependent histone deacetylase SIRT1 in the control of anti-bacterial defense. Mice with an intestinal specific Sirt1 deficiency (Sirt1int-/-) have more Paneth and goblet cells with a consequent rearrangement of the gut microbiota. From a mechanistic point of view, the effects on mouse intestinal cell maturation are mediated by SIRT1-dependent changes in the acetylation status of SPDEF, a master regulator of Paneth and goblet cells. Our results suggest that targeting SIRT1 may be of interest in the management of IBD and CAC.