Indole-3-carbinol attenuates lipopolysaccharide-induced acute respiratory distress syndrome through activation of AhR: role of CCR2+ monocyte activation and recruitment in the regulation of CXCR2+ neutrophils in the lungs

Introduction

Indole-3-carbinol (I3C) is found in cruciferous vegetables and used as a dietary supplement. It is known to act as a ligand for aryl hydrocarbon receptor (AhR). In the current study, we investigated the role of AhR and the ability of I3C to attenuate LPS-induced Acute Respiratory Distress Syndrome (ARDS).

Methods

To that end, we induced ARDS in wild-type C57BL/6 mice, Ccr2gfp/gfp KI/KO mice (mice deficient in the CCR2 receptor), and LyZcreAhRfl/fl mice (mice deficient in the AhR on myeloid linage cells). Additionally, mice were treated with I3C (65 mg/kg) or vehicle to investigate its efficacy to treat ARDS.

Results

I3C decreased the neutrophils expressing CXCR2, a receptor associated with neutrophil recruitment in the lungs. In addition, LPS-exposed mice treated with I3C revealed downregulation of CCR2+ monocytes in the lungs and lowered CCL2 (MCP-1) protein levels in serum and bronchoalveolar lavage fluid. Loss of CCR2 on monocytes blocked the recruitment of CXCR2+ neutrophils and decreased the total number of immune cells in the lungs during ARDS. In addition, loss of the AhR on myeloid linage cells ablated I3C-mediated attenuation of CXCR2+ neutrophils and CCR2+ monocytes in the lungs from ARDS animals. Interestingly, scRNASeq showed that in macrophage/monocyte cell clusters of LPS-exposed mice, I3C reduced the expression of CXCL2 and CXCL3, which bind to CXCR2 and are involved in neutrophil recruitment to the disease site.

Discussion

These findings suggest that CCR2+ monocytes are involved in the migration and recruitment of CXCR2+ neutrophils during ARDS, and the AhR ligand, I3C, can suppress ARDS through the regulation of immune cell trafficking.

6-Formylindolo[3,2-b]carbazole, a potent ligand for the aryl hydrocarbon receptor, attenuates concanavalin-induced hepatitis by limiting T-cell activation and infiltration of proinflammatory CD11b+ Kupffer cells

FICZ (6-formylindolo[3,2-b]carbazole) is a potent aryl hydrocarbon receptor agonist that has a poorly understood function in the regulation of inflammation. In this study, we investigated the effect of aryl hydrocarbon receptor activation by FICZ in a murine model of autoimmune hepatitis induced by concanavalin A. High-throughput sequencing techniques such as single-cell RNA sequencing and assay for transposase accessible chromatin sequencing were used to explore the mechanisms through which FICZ induces its effects. FICZ treatment attenuated concanavalin A-induced hepatitis, evidenced by decreased T-cell infiltration, decreased circulating alanine transaminase levels, and suppression of proinflammatory cytokines. Concanavalin A revealed an increase in natural killer T cells, T cells, and mature B cells upon concanavalin A injection while FICZ treatment reversed the presence of these subsets. Surprisingly, concanavalin A depleted a subset of CD55+ B cells, while FICZ partially protected this subset. The immune cells showed significant dysregulation in the gene expression profiles, including diverse expression of migratory markers such as CCL4, CCL5, and CXCL2 and critical regulatory markers such as Junb. Assay for transposase accessible chromatin sequencing showed more accessible chromatin in the CD3e promoter in the concanavalin A-only group as compared to the naive and concanavalin A-exposed, FICZ-treated group. While there was overall more accessible chromatin of the Adgre1 (F4/80) promoter in the FICZ-treated group, we observed less open chromatin in the Itgam (CD11b) promoter in Kupffer cells, supporting the ability of FICZ to reduce the infiltration of proinflammatory cytokine producing CD11b+ Kupffer cells. Taken together, these data demonstrate that aryl hydrocarbon receptor activation by FICZ suppresses liver injury through the limitation of CD3+ T-cell activation and CD11b+ Kupffer cell infiltration.

Production of MHCII-expressing classical monocytes increases during aging in mice and humans

Aging is associated with increased monocyte production and altered monocyte function. Classical monocytes are heterogenous and a shift in their subset composition may underlie some of their apparent functional changes during aging. We have previously shown that mouse granulocyte-monocyte progenitors (GMPs) produce "neutrophil-like" monocytes (NeuMo), whereas monocyte-dendritic cell progenitors (MDPs) produce monocyte-derived dendritic cell (moDC)-producing monocytes (DCMo). Here, we demonstrate that classical monocytes from the bone marrow of old male and female mice have higher expression of DCMo signature genes (H2-Aa, H2-Ab1, H2-Eb1, Cd74), and that more classical monocytes express MHCII and CD74 protein. Moreover, we show that bone marrow MDPs and classical monocytes from old mice yield more moDC. We also demonstrate higher expression of Aw112010 in old monocytes and that Aw112010 lncRNA activity regulates MHCII induction in macrophages, which suggests that elevated Aw112010 levels may underlie increased MHCII expression during monocyte aging. Finally, we show that classical monocyte expression of MHCII is also elevated during healthy aging in humans. Thus, aging-associated changes in monocyte production may underlie altered monocyte function and have implications for aging-associated disorders.

Yin and yang of cannabinoid CB1 receptor: CB1 deletion in immune cells causes exacerbation while deletion in non-immune cells attenuates obesity

While blockade of cannabinoid receptor 1 (CB1) has been shown to attenuate diet-induced obesity (DIO), its relative role in different cell types has not been tested. The current study investigated the role of CB1 in immune vs non-immune cells during DIO by generating radiation-induced bone marrow chimeric mice that expressed functional CB1 in all cells except the immune cells or expressed CB1 only in immune cells. CB1^−/− recipient hosts were resistant to DIO, indicating that CB1 in non-immune cells is necessary for induction of DIO. Interestingly, chimeras with CB1^−/− in immune cells showed exacerbation in DIO combined with infiltration of bone-marrow-derived macrophages to the brain and visceral adipose tissue, elevated food intake, and increased glucose intolerance. These results demonstrate the opposing role of CB1 in hematopoietic versus non-hematopoietic cells during DIO and suggests that targeting immune CB1 receptors provides a new pathway to ameliorate obesity and related metabolic disorders.

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Cannabinoid Receptor 1 (CB1), and not CB2, regulates diet-induced obesity (DIO)

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CB1 deficiency in non-immune cell types promotes DIO resistance

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CB1 deficiency in immune cells exacerbates DIO disease phenotype

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CB1 activation in immune cells is a potential therapeutic target for DIO attenuation

TLR-9 agonist CpG activates macrophages and modulates expression of microRNAs involved in cancer drug resistance and various signaling pathways

TLR-9 agonist, CpG induces pro-inflammatory immune response. We studied the immune response elicited in C57Bl/6 female mice by repeated stimulation of TLR-9 through multiple doses of CpG administration. Complete blood count analysis after CpG treatment revealed peripheral pancytopenia and the spleen showed splenomegaly. Flow cytometry analyses of spleen and liver mononuclear cells disclosed macrophage activation, evidenced by substantial increase in F4/80+ cells in the treatment group compared to control. Analysis of serum by ELISA demonstrated enhanced levels of pro-inflammatory cytokines, IL12/23, IL6 and TNFα in the CpG-treated group whereas no significant change was observed in the amount of anti-inflammatory cytokine, IL10. The spleen cells were further subjected to microarray analysis in order to examine the modulation of microRNA expression pattern following CpG treatment. Investigation of miRNA-mRNA relationships using the ingenuity pathway analysis (IPA) revealed differential expression of miRNAs associated with cancer drug resistance, HOTAIR and BAG signaling pathways along with microRNAs involved in immunomodulation. The major microRNAs altered with CpG treatment included mir27a, mir181, mir130a, mir487a, mir29b1, mir130a, mir3473b, mir21a, mir142 and mir144 targeting genes involved in drug resistance, apoptosis, cell cycle, angiogenesis and major histocompatibility complex-related proteins. Together, our studies demonstrate that chronic macrophage activation may lead to uncontrolled activation and proliferation of immune cells. (Supported by NIH grants P01AT003961, P20GM103641, R01AI129788, R01ES030144, R01AI160896 and R01AI123947).

Supported by NIH grants P01AT003961, P20GM103641, R01AI129788, R01ES030144, R01AI160896 and R01AI123947

Characterization of Altered Gene Expression and Histone Methylation in Peripheral Blood Mononuclear Cells Regulating Inflammation in COVID-19 Patients

The pandemic of COVID-19 has caused >5 million deaths in the world. One of the leading causes of the severe form of COVID-19 is the production of massive amounts of proinflammatory cytokines. Epigenetic mechanisms, such as histone/DNA methylation, miRNA, and long noncoding RNA, are known to play important roles in the regulation of inflammation. In this study, we investigated if hospitalized COVID-19 patients exhibit alterations in epigenetic pathways in their PBMCs. We also compared gene expression profiles between healthy controls and COVID-19 patients. Despite individual variations, the expressions of many inflammation-related genes, such as arginase 1 and IL-1 receptor 2, were significantly upregulated in COVID-19 patients. We also found the expressions of coagulation-related genes Von Willebrand factor and protein S were altered in COVID-19 patients. The expression patterns of some genes, such as IL-1 receptor 2, correlated with their histone methylation marks. Pathway analysis indicated that most of those dysregulated genes were in the TGF-β, IL-1b, IL-6, and IL-17 pathways. A targeting pathway revealed that the majority of those altered genes were targets of dexamethasone, which is an approved drug for COVID-19 treatment. We also found that the expression of bone marrow kinase on chromosome X, a member of TEC family kinases, was increased in the PBMCs of COVID-19 patients. Interestingly, some inhibitors of TEC family kinases have been used to treat COVID-19. Overall, this study provides important information toward identifying potential biomarkers and therapeutic targets for COVID-19 disease.

Dysregulated TP53 Among PTSD Patients Leads to Downregulation of miRNA let-7a and Promotes an Inflammatory Th17 Phenotype

Post-traumatic stress disorder (PTSD) is a psychiatric disorder and patients diagnosed with PTSD often express other comorbid health issues, particularly autoimmune and inflammatory disorders. Our previous reports investigating peripheral blood mononuclear cells (PBMCs) from PTSD patients showed that these patients exhibit an increased inflammatory T helper (Th) cell phenotype and widespread downregulation of microRNAs (miRNAs), key molecules involved in post-transcriptional gene regulation. A combination of analyzing prior datasets on gene and miRNA expression of PBMCs from PTSD and Control samples, as well as experiments using primary PBMCs collected from human PTSD and Controls blood, was used to evaluate TP53 expression, DNA methylation, and miRNA modulation on Th17 development. In the current report, we note several downregulated miRNAs were linked to tumor protein 53 (TP53), also known as p53. Expression data from PBMCs revealed that compared to Controls, PTSD patients exhibited decreased TP53 which correlated with an increased inflammatory Th17 phenotype. Decreased expression of TP53 in the PTSD population was shown to be associated with an increase in DNA methylation in the TP53 promotor region. Lastly, the most significantly downregulated TP53-associated miRNA, let-7a, was shown to negatively regulate Th17 T cells. Let-7a modulation in activated CD4+ T cells was shown to influence Th17 development and function, via alterations in IL-6 and IL-17 production, respectively. Collectively, these studies reveal that PTSD patients could be susceptible to inflammation by epigenetic dysregulation of TP53, which alters the miRNA profile to favor a proinflammatory Th17 phenotype.

Targeting AhR as a Novel Therapeutic Modality against Inflammatory Diseases

For decades, activation of Aryl Hydrocarbon Receptor (AhR) was excluded from consideration as a therapeutic approach due to the potential toxic effects of AhR ligands and the induction of the cytochrome P450 enzyme, Cyp1a1, following AhR activation. However, it is now understood that AhR activation not only serves as an environmental sensor that regulates the effects of environmental toxins, but also as a key immunomodulator where ligands induce a variety of cellular and epigenetic mechanisms to attenuate inflammation. Thus, the emergence of further in-depth research into diverse groups of compounds capable of activating this receptor has prompted reconsideration of its use therapeutically. The aim of this review is to summarize the body of research surrounding AhR and its role in regulating inflammation. Specifically, evidence supporting the potential of targeting this receptor to modulate the immune response in inflammatory and autoimmune diseases will be highlighted. Additionally, the opportunities and challenges of developing AhR-based therapies to suppress inflammation will be discussed.

Effects of Acute 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Exposure on the Circulating and Cecal Metabolome Profile

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a polyhalogenated planar hydrocarbon belonging to a group of highly toxic and persistent environmental contaminants known as "dioxins". TCDD is an animal teratogen and carcinogen that is well characterized for causing immunosuppression through activation of aryl hydrocarbon receptor (AHR). In this study, we investigated the effect of exposure of mice to an acute dose of TCDD on the metabolic profile within the serum and cecal contents to better define the effects of TCDD on host physiology. Our findings demonstrated that within the circulating metabolome following acute TCDD exposure, there was significant dysregulation in the metabolism of bioactive lipids, amino acids, and carbohydrates when compared with the vehicle (VEH)-treated mice. These widespread changes in metabolite abundance were identified to regulate host immunity via modulating nuclear factor-kappa B (NF-κB) and extracellular signal-regulated protein kinase (ERK1/2) activity and work as biomarkers for a variety of organ injuries and dysfunctions that follow TCDD exposure. Within the cecal content of mice exposed to TCDD, we were able to detect changes in inflammatory markers that regulate NF-κB, markers of injury-related inflammation, and changes in lysine degradation, nicotinamide metabolism, and butanoate metabolism, which collectively suggested an immediate suppression of broad-scale metabolic processes in the gastrointestinal tract. Collectively, these results demonstrate that acute TCDD exposure results in immediate irregularities in the circulating and intestinal metabolome, which likely contribute to TCDD toxicity and can be used as biomarkers for the early detection of individual exposure.

Regulation of Intestinal Stem Cell Stemness by the Aryl Hydrocarbon Receptor and Its Ligands

Maintenance of intestinal homeostasis requires the integration of immunological and molecular processes together with environmental, diet, metabolic and microbial cues. Key to this homeostasis is the proper functioning of epithelial cells originating from intestinal stem cells (ISCs). While local factors and numerous molecular pathways govern the ISC niche, the conduit through which these processes work in concordance is the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, whose role in immunoregulation is critical at barrier surfaces. In this review, we discuss how AhR signaling is emerging as one of the critical regulators of molecular pathways involved in epithelial cell renewal. In addition, we examine the putative contribution of specific AhR ligands to ISC stemness and epithelial cell fate.

Cannabinoid Receptor Activation on Haematopoietic Cells and Enterocytes Protects against Colitis

BACKGROUND AND AIMS

Cannabinoid receptor [CB] activation can attenuate inflammatory bowel disease [IBD] in experimental models and human cohorts. However, the roles of the microbiome, metabolome, and the respective contributions of haematopoietic and non-haematopoietic cells in the anti-colitic effects of cannabinoids have yet to be determined.

METHODS

Female C57BL/6 mice were treated with either cannabidiol [CBD], Δ 9-tetrahydrocannabinol [THC], a combination of CBD and THC, or vehicle, in several models of chemically induced colitis. Clinical parameters of colitis were assessed by colonoscopy, histology, flow cytometry, and detection of serum biomarkers; single-cell RNA sequencing and qRT-PCR were used to evaluate the effects of cannabinoids on enterocytes. Immune cell transfer from CB2 knockout mice was used to evaluate the contribution of haematopoietic and non-haematopoietic cells to colitis protection.

RESULTS

We found that THC prevented colitis and that CBD, at the dose tested, provided little benefit to the amelioration of colitis, nor when added synergistically with THC. THC increased colonic barrier integrity by stimulating mucus and tight junction and antimicrobial peptide production, and these effects were specific to the large intestine. THC increased colonic Gram-negative bacteria, but the anti-colitic effects of THC were independent of the microbiome. THC acted both on immune cells via CB2 and on enterocytes, to attenuate colitis.

CONCLUSIONS

Our findings demonstrate how cannabinoid receptor activation on both immune cells and colonocytes is critical to prevent colonic inflammation. These studies also suggest how cannabinoid receptor activation can be used as a preventive and therapeutic modality against colitis.

Increased H3K4me3 methylation and decreased miR-7113-5p expression lead to enhanced Wnt/β-catenin signaling in immune cells from PTSD patients leading to inflammatory phenotype

BACKGROUND

Posttraumatic stress disorder (PTSD) is a psychiatric disorder accompanied by chronic peripheral inflammation. What triggers inflammation in PTSD is currently unclear. In the present study, we identified potential defects in signaling pathways in peripheral blood mononuclear cells (PBMCs) from individuals with PTSD.

METHODS

RNAseq (5 samples each for controls and PTSD), ChIPseq (5 samples each) and miRNA array (6 samples each) were used in combination with bioinformatics tools to identify dysregulated genes in PBMCs. Real time qRT-PCR (24 samples each) and in vitro assays were employed to validate our primary findings and hypothesis.

RESULTS

By RNA-seq analysis of PBMCs, we found that Wnt signaling pathway was upregulated in PTSD when compared to normal controls. Specifically, we found increased expression of WNT10B in the PTSD group when compared to controls. Our findings were confirmed using NCBI's GEO database involving a larger sample size. Additionally, in vitro activation studies revealed that activated but not naïve PBMCs from control individuals expressed more IFNγ in the presence of recombinant WNT10B suggesting that Wnt signaling played a crucial role in exacerbating inflammation. Next, we investigated the mechanism of induction of WNT10B and found that increased expression of WNT10B may result from epigenetic modulation involving downregulation of hsa-miR-7113-5p which targeted WNT10B. Furthermore, we also observed that WNT10B overexpression was linked to higher expression of H3K4me3 histone modification around the promotor of WNT10B. Additionally, knockdown of histone demethylase specific to H3K4me3, using siRNA, led to increased expression of WNT10B providing conclusive evidence that H3K4me3 indeed controlled WNT10B expression.

CONCLUSIONS

In summary, our data demonstrate for the first time that Wnt signaling pathway is upregulated in PBMCs of PTSD patients resulting from epigenetic changes involving microRNA dysregulation and histone modifications, which in turn may promote the inflammatory phenotype in such cells.

Activation of Cannabinoid Receptor 2 Prevents Colitis-Associated Colon Cancer through Myeloid Cell De-activation Upstream of IL-22 Production

Intestinal disequilibrium leads to inflammatory bowel disease (IBD), and chronic inflammation predisposes to oncogenesis. Antigen-presenting dendritic cells (DCs) and macrophages can tip the equilibrium toward tolerance or pathology. Here we show that delta-9-tetrahydrocannabinol (THC) attenuates colitis-associated colon cancer and colitis induced by anti-CD40. Working through cannabinoid receptor 2 (CB2), THC increases CD103 expression on DCs and macrophages and upregulates TGF-β1 to increase T regulatory cells (Tregs). THC-induced Tregs are necessary to remedy systemic IFNγ and TNFα caused by anti-CD40, but CB2-mediated suppression of APCs by THC quenches pathogenic release of IL-22 and IL-17A in the colon. By examining tissues from multiple sites, we confirmed that THC affects DCs, especially in mucosal barrier sites in the colon and lungs, to reduce DC CD86. Using models of colitis and systemic inflammation we show that THC, through CB2, is a potent suppressor of aberrant immune responses by provoking coordination between APCs and Tregs.

Long Noncoding RNA AW112010 Promotes the Differentiation of Inflammatory T Cells by Suppressing IL-10 Expression through Histone Demethylation

Long noncoding RNAs (lncRNAs) have been demonstrated to play important regulatory roles in gene expression, from histone modification to protein stability. However, the functions of most identified lncRNAs are not known. In this study, we investigated the role of an lncRNA called AW112010. The expression of AW112010 was significantly increased in CD4⁺ T cells from C57BL/6J mice activated in vivo with myelin oligodendrocyte glycoprotein, Staphylococcal enterotoxin B, or in vitro with anti-CD3 anti-CD28 mAbs, thereby demonstrating that activation of T cells leads to induction of AW112010. In contrast, anti-inflammatory cannabinoids such as cannabidiol or δ-9-tetrahydrocannabinol decreased the expression of AW112010 in T cells. Interestingly, the expression of AW112010 was high in in vitro-polarized Th1 and Th17 cells but low in Th2 cells, suggesting that this lncRNA may regulate inflammation. To identify genes that might be regulated by AW112010, we used chromatin isolation by RNA purification, followed by sequencing. This approach demonstrated that AW112010 regulated the transcription of IL-10. Additionally, the level of IL-10 in activated T cells was low when the expression of AW112010 was increased. Use of small interfering RNA to knock down AW112010 expression in activated T cells led to increased IL-10 expression and a decrease in the expression of IFN-γ. Further studies showed that AW112010 interacted with histone demethylase KDM5A, which led to decreased H3K4 methylation in IL-10 gene locus. Together, these studies demonstrate that lncRNA AW112010 promotes the differentiation of inflammatory T cells by suppressing IL-10 expression through histone demethylation.

Functions and mechanisms of chondroitin disaccharide-induced miRNAs in the regulation of CD44 expression involved in the development of experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic demyelinating neurodegenerative disease of the central nervous system (CNS). In this study, we investigated the effects of chondroitin disaccharide and its induced miR-29b and miR-199b on CD44 expression in mouse lymphocytes, as well as the effects of miR-29b and miR-199b on the development and progression of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of MS. The effects of chondroitin sulfate disaccharide on the changes in cellular immunity were investigated in EAE induced in mice by MOG and PTX. Real-time PCR and flow cytometry were used to investigate the effects of the anti-miRs and mimics of miR-29b and miR-199b on CD44 expression in mouse splenocytes after electroporation. After the transduction of antai-miRs and mimics of miR-29b and miR-199b into splenocytes, they were adoptively transferred into mice intravenously and the changes in immune cells and cytokines were analyzed by flow cytometry and ELISA. Our studies revealed that chondroitin disaccharide significantly up-regulated several specific miRNAs such as miR-29b and miR-199b, and thus dramatically inhibited EAE in mice. In vitro and in vivo studies demonstrated that miR-29b and miR-199b could down-regulate the expression of CD44 and modulate the expression of IL-17 and IL-4 in the lymphocytes from EAE mice. Therefore, miR-29b and miR-199b could inhibit the expression of CD44, modulate the expression of IL-4 and IL-17, and thus suppress lymphocyte proliferation and migration, leading to significant inhibition of EAE development. Thus, miR-29b and miR-199b could also be used as therapeutic targets for EAE and MS.

Treatment with natural AhR ligand leads to amelioration of LPS-induced acute lung injury by decreasing microRNA 29b-2-5p expression targeting increased IL-22 production

Acute lung injury and acute respiratory distress syndrome (ALI/ARDS) are severe pulmonary inflammatory diseases that cause destruction and remolding of the lung epithelial barrier, which may lead to restriction of pulmonary functionality and/or death. Indole-3-carbinol (I3C), a naturally occurring Ahr ligand has been shown to ameliorate multiple inflammatory disorders. Our studies are aimed at determining whether treatment with the I3C affects reparative reepithelialization and restores lung functioning through an immune-mediated mechanism. Towards this, 5mg/kg of LPS was intranasally injected in C57BL/6 mice to induce ALI. Three hours following LPS administration, the mice were treated with 40mg/kg I3C. After 48 hours, we examined lung functions using Buxco plethysmography and noticed LPS + I3C treated-mice have similar functionality as naïve mice in multiple parameters including ratio of time peak expiratory flow (Rpef), rejection index (Rinx), and tidal volume (TV) basal pulmonary functions whereas LPS+vehicle treated mice showed alterations. Histopathological analysis revealed fibrotic tissue in lung sections of LPS + Vehicle administered mice, but not in LPS + I3C treated mice. In addition, I3C increased the expression of Th22 (CD3+CD4+IL22+) cells, which are key mediators of epithelial cell layer protection, antimicrobial peptide production, and reepithelialization improvement. I3C increased IL-22 expression in bronchoalveolar lavage fluid, and decreased the expression in miR-29b-2-5p transcript that directly regulates IL-22 expression. In conclusion, our studies suggest that Ahr ligand I3C alleviates lung injury by maintaining lung epithelium integrity which may be mediated by IL-22 secreting T cells.

Single cell profiling illustrates down-regulation of GM42031 in macrophages and microglia as a potential mechanism of neuroinflammation in transgenic GFAP-gp120 mice

Over thirty percent of individuals infected with human immunodeficiency virus type 1 (HIV) worldwide suffer from HIV-associated neurocognitive disorder (HAND). GFAP-gp120 transgenic (Tg) mice serve as an excellent model system for HAND because they manifest the same neuropathological attributes observed in the brains of AIDS patients. In this study, we sought to identify novel genes associated with the GFAP-gp120 neurodegenerative mouse model. Von Frey filament and hot plate tests on 8 month old GFAP-gp120 mice resulted in a significant increase in mechanical and thermal nociception in Tg versus wild-type mice. Neuropathology was confirmed via immunohistochemistry of MAP2, Synaptophysin, Iba-1, and GFAP. The MAP2 and Synaptophysin allowed us to visualize dendritic density and synaptic loss. Infiltration of macrophages was observed with anti-Iba-1 and astrocytosis with anti-GFAP Abs. Additionally, single cell RNA sequencing (scRNASeq) of encephalitogenic mononuclear cells illustrated 10 distinct clusters of cells. These clusters included: astrocytes, neurons, oligodendrocytes, endothelial cells, microglia, and macrophages. Differential expression analysis showed decreased expression of GM42031 in Tg macrophages and microglia. This locus is currently unclassified and thought to be either a long non coding RNA (lncRNA) or a gene for a NYNRIN-like protein. Until now, this particular RNA has not been associated with the GFAP-gp120 disease model. However, there has been some association of GM42031 with macrophage regulation in Parkinson’s disease and colitis models. Together our study provides novel insights into the immunopathology of HAND that may form the basis for development of effective therapeutics.

Indole-3-carbinol prevents colitis and regulates microbial dysbiosis by induction of anti-microbial peptides and mucins in an IL-22 dependent manner

Colitis is an inflammatory bowel disease (IBD) characterized by acute or chronic inflammation within the colon and significant alterations in the microbiome, a term known as microbial dysbiosis. In our previous reports, we showed that a natural indole product and aryl hydrocarbon receptor (AhR) ligand found in cruciferous vegetables (Indole-3-carbinol, or I3C) was able to reduce colitis-induced disease severity and prevent colitis-associated microbial dysbiosis. In the current study, we performed 10× Genomics single cell analysis on colonic epithelial cells (CECs) and lamina propria-derived immune cells from 2,4,6-Trinitrobenzenesulfonic acid solution (TNBS)-induced colitis treated with or without I3C. Single cell analysis showed that treatment with I3C results in alterations in the immune cell profiles, which included increases in both anti-inflammatory regulatory T cells (Tregs), as well as IL-22 producing cells. Additionally, CEC cells in I3C-treated mice showed an increase in host defense responses to microbes, such as mucin (muc2) and anti-microbial peptide (AMP) production. Increased AMP production included mainly beta-defensins (BDs) and regenerating islet-derived protein 3 (Reg3) types. Gene transcriptome array and PCR validation experiments confirmed the results obtained from the single cell analysis. Lastly, as IL-22 is known to play a key role in regulating host defense responses by mucin and AMP production, we neutralized IL-22 in vivo and showed that the ability of I3C to reduce colitis severity and prevent colitis-associated microbial dysbiosis was lost.

2,3,7,8-Tetrachlorodibenzo-p-dioxin Induces Gimap5 Expression to Ameliorate Concanavalin-Induced T Cell-Mediated Liver Injury

GTPase of the immune-associated protein 5 (Gimap5) has been implicated in immune cell maintenance and development. A mouse model comparable to autoimmune hepatitis in humans was used to study the alterations induced in the gene expression profile of immune cells upon administration of environmental toxin 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD). In this study, we tested the hypothesis that TCDD is capable of modulating gene expression to ameliorate autoimmune hepatitis severity. Mice were injected intravenously with 12.5 mg/kg concanavalin A (ConA) and treated intraperitoneally one hour after challenge with vehicle or 10 μg/kg TCDD. TCDD-treated mice showed lower levels of liver injury enzymes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), as compared to vehicle-treated mice. Histopathological analysis revealed a reduction in liver damage in the TCDD-treated group as compared to the vehicle-treated control. Furthermore, flow cytometric analysis of liver-infiltrating mononuclear cells demonstrated that following treatment with TCDD, there was an increase in FoxP3+CD4+ Tregs as well as a decrease in proinflammatory Tbet+ Th1 and RORγt+ Th17 T helper cell subtypes after induction of the disease. Single cell RNA-sequencing was conducted on liver mononuclear cells to further assess the changes induced by TCDD. The gene expression profile showed that TCDD treatment significantly upregulated the expression of vital genes such as Gimap5, a maintenance gene for normal liver function and survival of T cells. In summary, our data suggests that TCDD is capable of inducing Gimap5 expression in autoimmune hepatitis, which in turn modulates the progression of this disease.

Altered Gut DNA virome diversity associated HMGB1 release regulates reactive Astrocytes-induced IL6 release preferably via TLR4-NFkB pathway in experimental Gulf War Illness

In a recent study, we showed that the gut DNA bacteriophage dysbiosis in Gulf War Illness (GWI) was strongly associated with compromised intestinal epithelial cell integrity, increased circulatory IL6 and neuroinflammation. The current study further investigates the mechanism of DNA bacteriophage-IL6 axis in neuroinflammation. Advancing the previous findings, we show that viral dysbiosis positively correlated with high mobility group box protein 1 (HMGB1; a damage-associated molecular pattern) expression and release in circulation following GWI induction in mice. The circulatory HMGB1 activated brain Astrocytes via altering brain endothelial tight junction proteins and crossing the blood-brain barrier. Interestingly, both in GWI mice and mouse primary Astrocytes cell culture showed an increased brain IL6 mRNA and subsequent protein expression. However, GWI mice treated with Ribavirin (used for partial gut viral sterility) showed decreased intestinal HMGB1 and brain IL6 expression. Mechanistically, HMGB1 activated innate immune response via IRAKs-IKKα-NFkB instead of either RAGE-MAPK or PI3K-mTOR pathway. Surprisingly, inhibition of RAGE or PI3K pathway in HMGB1 primed mouse Astrocyte cells showed a significant increase in IL6 expression and release suggesting NFkB activation as a preferential pathway in GWI-Astrocyte-induced IL6 release. In summary, GWI-associated gut viral dysbiosis associated intestinal HMGB1 release activates brain Astrocytes and IL6 release via toll-like receptor 4-NFkB dependent pathway, thus causing neuroinflammation in GWI. The above mechanism can form a basis for studying inflammation-associated neurocognitive abnormalities in GWI.

Epigenetic regulation of C-Kitlo FcɛR1a+ mast cells by cannabidiol during staphylococcal enterotoxin B-induced liver injury

Although recent studies have established cannabidiol (CBD) as a potent anti-inflammatory agent, the mechanisms governing these processes remain unclear. Our previous research demonstrated that CBD treatment induced expansion of CD11b+Gr-1+MDSC in the peritoneum, which suppressed T cell functions leading to attenuation of staphylococcal enterotoxin B (SEB)-mediated liver inflammation in mice. Using the same model, we characterize the effects of CBD administration in the liver. Briefly, mice were injected intraperitoneally (I.P.) with 50mg/kg of CBD for 4 days (d), followed by SEB challenge on d 3. Flow cytometry analysis revealed a significant reduction in Vβ8+ CD8+ T cells. In agreement with our earlier findings, mice treated with CBD displayed robust expansion of Gr-1+ MDSC in the liver, which was primarily comprised of Ly6CHI MHCIILO leukocytes. As mast cells have been found to play a role in CBD-mediated induction of MDSC via increased peroxisome proliferator-activated receptor gamma (PPARγ) signaling, we examined changes to liver mast cell populations. We discovered two distinct subsets of mast cells, C-KithiFcɛR1a+ and C-Kitlo FcɛR1a+present in the liver. CBD treatment promoted expansion of the C-Kitlo FcɛR1a+ subset. Analysis by miRNA microarray displayed enrichment of miRNAs targeting mast cell growth factor, KIT ligand (KITLG), and significant downregulation of miR-217-5p, which is conserved for the co-activator of PPARγ (PPARγC1A). Increased gene expression of PPARγ was confirmed by single-cell RNA sequencing (sc-RNAseq). Taken together, our results identify CBD induced epigenetic reduction of C-Kit expression and KITLG signaling in mast cells to favor PPARγ signaling as a novel anti-inflammatory mechanism.

Cannabidiol alters macrophage differentiation resulting in accumulation of immunosuppressive myeloid cells and dendritic cells

Cannabidiol (CBD) is a non-psychoactive phytocannabinoid that has anti-inflammatory properties; however the precise immunological mechanisms involved are not clear. Research from our laboratory has established that CBD promotes expansion of immunosuppressive myeloid-derived suppressor cells (MDSC), which are immature leukocytes thought to have stalled their differentiation towards mature myeloid lineages such as macrophages and dendritic cells (DC). In the current study, we aimed to better understand the mechanisms of CBD-altered hematopoiesis. We performed flow cytometry and single cell RNA sequencing (sc-RNAseq) on peritoneal cells from C57BL/6 mice treated with Vehicle (Veh) or CBD (20mg/kg, i.p.). Consistent with our previous studies, CBD promoted accumulation of MDSCs after 24h, which dissipated after 48h. Strikingly, MDSC accumulation was preceded by ablation of macrophages, which was maintained beyond 48h. In addition, accumulation of DCs started at 12h and accelerated through 48h. Similarly, sc-RNAseq of peritoneal cells harvested at 24h showed two distinct populations of cells expressing Adgre1, which encodes F4/80. These two clusters were distinct between Veh- and CBD-treated mice due to their drastically altered transcriptomes. The Veh-distinct cluster was comprised of macrophages expressing complement genes, while the CBD-distinct cluster was comprised of MDSCs expressing Arg1. Furthermore, the DC cluster expressing Ccr2 was enlarged in CBD-treated mice. Together, our results demonstrate that CBD drastically alters hematopoiesis, depleting macrophages and promoting MDSCs and DCs. These findings suggest CBD treatment may be beneficial in various macrophage-driven inflammatory disorders.

Efficacy of cannabidiol treatment in experimental MS is due to immunosuppressive activity of myeloid cells in CNS downregulating recruitment of CD4+ T cells, proinflammatory chemokines and gasdermin D expression

Cannabidiol (CBD) is a nonpsychoactive ingredient from Cannabis that has garnered attention in the medical community due to its anti-inflammatory properties and therapeutic potential. CBD has in particular become a popular alternative medicine among individuals with autoimmune disorders due to CBD lacking the side effects and costs associated with immunosuppressants. To better define how CBD inhibits inflammation, we studied the effects of orally administering CBD (20mg/kg) in experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis. Using single cell RNA sequencing on cells isolated from the central nervous system (CNS) of EAE mice, we demonstrated that CBD treatment inhibits neuroinflammation by regulating gene expression and infiltration of myeloid cells. Within the resident and infiltrating myeloid cells of the CNS, there was decreased expression of inflammatory cytokines and chemokines (CXCL9, CXCL10, IL-18) associated with neuroinflammation and CD4+ T cell recruitment, pyroptosis initiators (gasdermin D; Gsdmd), oxide synthesizers (Arg1) and antigen presentation mediators (CD40) in CBD-treatment group. Additionally, CBD yielded an increase in the polymorphonuclear myeloid derived suppressor cells in the CNS, signifying immunotolerance induction at the site of inflammation. In the VEH treated mice, we found CD4+ T cells that express the receptor for IL-18 (IL-18r1) that are absent in CBD treated mice, suggesting CBD affects T cell activity via inhibition of myeloid cell activity. This data shows that CBD treatment ameliorates EAE by inhibiting infiltration, pro-inflammatory cytokine production, antigen presentation, T cell recruitment and pyroptosis of myeloid cells in the CNS.

Regulation of macrophages in tumor microenvironment by microRNA in T cell lymphoma-bearing mice

The tumor microenvironment is a complex niche created by cancer cells to survive and evade the immune system. Macrophages (Mϕs) are considered to be one of the most abundant cells in the cancer microenvironment. Studies have shown that cancer cells have predilection for the M2 cell phenotype compared to M1 in the microenvironment, because M2 Mϕs promote immunosuppression and subsequently enhance tumor cell proliferation and angiogenesis. The aim of this study was to compare the gene expression profile of tumor-associated Mϕs (TAMs) and splenic Mϕs from tumor-bearing hosts (TBHs) and determine the epigenetic regulation of altered genes. For this purpose, C57BL/6 mice were injected with 1×106 EL4 cancer cells subcutaneous to induce tumor growth and 10 days later, TAMs and splenic Mϕs were isolated. Cell phenotyping by flow cytometry showed that there was an increase in M2 cells in TAMs when compared to splenic Mϕs in TBHs. TAMs also exhibited increase in IL-10, IL-6, VEGFA, and ARG-1 whereas there was a decrease in the expression of MYD88, PTEN, TGFβ3 and P53 when compared to splenic Mϕs in TBHs. Analysis of the microRNA profile of the Mϕs showed differential regulation and using ingenuity pathway analysis (IPA), we found various miRs (miR-21a, miR-30a, miR-30c, miR-125b, miR-155) were upregulated. These miRs targeted MYD88, PTEN and P53, which leads to the overexpression of IL10, known to skew Mϕ polarization to an M2 phenotype. In summary, these studies demonstrate that several miRs regulate IL10 to polarize TAMs from an M1 to M2 phenotype in the tumor microenvironment. (Supported by NIH P01AT003961, P20GM103641, R01AI129788, R01 ES030144 and R01AI123947)

Resveratrol mediates regulation of genes through microRNAs in the gut epithelial cells that may play a role in the gut health and amelioration of EAE in mice

Resveratrol (RES), found abundantly in red grapes, blue berries and peanuts, is an anti-inflammatory, anticancer, and antioxidant compound. We have previously shown that RES ameliorated EAE in mice regulating immune cell functions and differentiation. In this study, we investigated the effect of RES on gene expression in the gut epithelial cells of mice with EAE. To this end, epithelial cells from small intestine (SI) and colons of mice with EAE treated with vehicle or RES were isolated. Transcriptome arrays using total RNAs from epithelial cells of SI and colons were performed and data obtained from the arrays were analyzed using Transcriptome Analysis Console software. Results showed that there were 1,591 (1165 in SI and 426 in colon) genes that were up- or down-regulated (>2-fold) in the epithelial cells of mice with EAE treated with RES, when compared to vehicle. We selected two genes, α-defensins and Mucin 3, for further analysis. Upon analysis of their expression in the gut epithelial cells, α-defensins was downregulated in SI while Mucin 3 was upregulated in colon of EAE mice treated with RES. To understand the regulation of these two genes in the gut, we investigated the role of microRNAs (miRs). There were two miRs, miR-378 and miR-338, that showed strong binding affinity for α-defensins and Mucin 3 respectively. Upon analysis of their expression in epithelial cells, miR-378 was upregulated but miR-338 was downregulated, demonstrating their possible role in the regulation of α-defensins and Mucin 3 genes. Data obtained from this study demonstrates a possible role of miRs in the regulation of genes in the gut epithelial cells may play a role in improving the health of the gut and amelioration of EAE in mice.

Indole-3-carbinol prevents colitis and associated microbial dysbiosis in an IL-22-dependent manner

Colitis, an inflammatory bowel disease, is caused by a variety of factors, but luminal microbiota are thought to play crucial roles in disease development and progression. Indole is produced by gut microbiota and is believed to protect the colon from inflammatory damage. In the current study, we investigated whether indole-3-carbinol (I3C), a naturally occurring plant product found in numerous cruciferous vegetables, can prevent colitis-associated microbial dysbiosis and attempted to identify the mechanisms. Treatment with I3C led to repressed colonic inflammation and prevention of microbial dysbiosis caused by colitis, increasing a subset of gram-positive bacteria known to produce butyrate. I3C was shown to increase production of butyrate, and when mice with colitis were treated with butyrate, there was reduced colonic inflammation accompanied by suppression of Th17 and induction of Tregs, protection of the mucus layer, and upregulation in Pparg expression. Additionally, IL-22 was increased only after I3C but not butyrate administration, and neutralization of IL-22 prevented the beneficial effects of I3C against colitis, as well as blocked I3C-mediated dysbiosis and butyrate induction. This study suggests that I3C attenuates colitis primarily through induction of IL-22, which leads to modulation of gut microbiota that promote antiinflammatory butyrate.

Resveratrol Downregulates miR-31 to Promote T Regulatory Cells during Prevention of TNBS-Induced Colitis

SCOPE

Colitis, an inflammatory bowel disease, is associated with aberrant regulation of the colonic mucosal immune system. Resveratrol, a natural plant product, has been found to exert anti-inflammatory properties and attenuate the development of murine colitis. In the current study, the role of microRNA (miR) in the ability of resveratrol to suppress colonic inflammation is examined.

METHODS AND RESULTS

BALB/C mice with 2,4,6-Trinitrobenzenesulfonic acid solution (TNBS)-induced colitis, when treated with resveratrol, show improved clinical outcomes and reduce induction of inflammatory T cells (Th17 and Th1) while increasing CD4+Foxp3+ regulatory T cells (Tregs) and IL-10-producing CD4+ T cells. miR microarray analysis and polymerase chain reaction (PCR) validation from CD4+ T cells show treatment with resveratrol decreases the expression of several miRs (miR-31, Let7a, miR-132) that targets cytokines and transcription factors involved in anti-inflammatory T cell responses (Foxp3 and TGF-β). Transfection studies with miR-31 confirm that this miR directly regulates the expression of Foxp3. Lastly, analysis of public data from human patients with ulcerative colitis reveals that miR-31 expression is significantly increased when compared to controls.

CONCLUSION

Together, the current study demonstrates that resveratrol-mediated attenuation of colitis may be regulated by miR-31 through induction of Tregs and miR-31 may serve as a therapeutic target for human colitis.

AhR Activation by TCDD (2,3,7,8-Tetrachlorodibenzo-p-dioxin) Attenuates Pertussis Toxin-Induced Inflammatory Responses by Differential Regulation of Tregs and Th17 Cells Through Specific Targeting by microRNA

The Aryl Hydrocarbon Receptor (AhR) is a transcription factor that, when activated by ligand-binding, has been shown to regulate the immune response. Pertussis Toxin (PTX) is a virulence factor found in Bordetella pertussis, a human respiratory pathogen that causes whooping cough. PTX promotes colonization and disease promotion by triggering a heightened inflammatory response. The role of AhR in the regulation of PTX-mediated inflammation has not previously been studied. In the current study, we investigate if AhR activation by 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a well characterized ligand, can attenuate PTX-mediated systemic inflammation. To that end, C57BL/6 mice were injected intraperitoneally (IP) with PTX twice and treated with TCDD or vehicle (VEH). The PTX+VEH group showed elevated levels of pro-inflammatory cytokines (IL-17A, IL-6, and IFNγ) in serum and increased proportions of CD4+ Th1 and Th17 cells in their spleens. In contrast, the PTX+TCDD group showed significantly lower levels of these inflammatory cytokines and decreased proportions of Th1 and Th17 cells, but increased proportions of Th2 and FoxP3+Tregs when compared to the PTX+VEH group. PTX+TCDD treated mice also showed elevated levels of IL-10, and TFG-b, potent anti-inflammatory cytokines. MicroRNAs (miRs) analysis of CD4+ T cells from the spleens of the PTX+TCDD treated mice revealed significant alterations in their expression and several of these miRs targeted cytokines and signaling molecules involved in inflammation. Specifically, the PTX+TCDD group had a significantly enhanced expression of miR-3082-5p that targeted IL-17, and a decreased expression of miR-1224-5p, which targeted FoxP3. Transfection studies with these miR mimics and inhibitors confirmed the specificity of the target genes. The current study suggests that AhR activation by TCDD suppresses PTX-induced inflammation through miR regulation that triggers reciprocal polarization of Tregs and Th17 cells and also suggests that AhR activation may serve as a treatment modality to suppress heightened inflammation induced during B. pertussis infection.

Prolonged high-fat-diet feeding promotes non-alcoholic fatty liver disease and alters gut microbiota in mice

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has become an epidemic largely due to the worldwide increase in obesity. While lifestyle modifications and pharmacotherapies have been used to alleviate NAFLD, successful treatment options are limited. One of the main barriers to finding safe and effective drugs for long-term use in NAFLD is the fast initiation and progression of disease in the available preclinical models. Therefore, we are in need of preclinical models that (1) mimic the human manifestation of NAFLD and (2) have a longer progression time to allow for the design of superior treatments.

AIM

To characterize a model of prolonged high-fat diet (HFD) feeding for investigation of the long-term progression of NAFLD.

METHODS

In this study, we utilized prolonged HFD feeding to examine NAFLD features in C57BL/6 male mice. We fed mice with a HFD (60% fat, 20% protein, and 20% carbohydrate) for 80 wk to promote obesity (Old-HFD group, n = 18). A low-fat diet (LFD) (14% fat, 32% protein, and 54% carbohydrate) was administered for the same duration to age-matched mice (Old-LFD group, n = 15). An additional group of mice was maintained on the LFD (Young-LFD, n = 20) for a shorter duration (6 wk) to distinguish between age-dependent and age-independent effects. Liver, colon, adipose tissue, and feces were collected for histological and molecular assessments.

RESULTS

Prolonged HFD feeding led to obesity and insulin resistance. Histological analysis in the liver of HFD mice demonstrated steatosis, cell injury, portal and lobular inflammation and fibrosis. In addition, molecular analysis for markers of endoplasmic reticulum stress established that the liver tissue of HFD mice have increased phosphorylated Jnk and CHOP. Lastly, we evaluated the gut microbial composition of Old-LFD and Old-HFD. We observed that prolonged HFD feeding in mice increased the relative abundance of the Firmicutes phylum. At the genus level, we observed a significant increase in the abundance of Adercreutzia, Coprococcus, Dorea, and Ruminococcus and decreased relative abundance of Turicibacter and Anaeroplasma in HFD mice.

CONCLUSION

Overall, these data suggest that chronic HFD consumption in mice can mimic pathophysiological and some microbial events observed in NAFLD patients.

Combination of Cannabinoids, Δ9- Tetrahydrocannabinol and Cannabidiol, Ameliorates Experimental Multiple Sclerosis by Suppressing Neuroinflammation Through Regulation of miRNA-Mediated Signaling Pathways

Multiple sclerosis (MS) is a chronic and disabling disorder of the central nervous system (CNS) characterized by neuroinflammation leading to demyelination. Recently a combination of Δ9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) extracted from Cannabis has been approved in many parts of the world to treat MS-related spasticity. THC+CBD combination was also shown to suppresses neuroinflammation, although the mechanisms remain to be further elucidated. In the current study, we demonstrate that THC+CBD combination therapy (10 mg/kg each) but not THC or CBD alone, attenuates murine experimental autoimmune encephalomyelitis (EAE) by reducing neuroinflammation and suppression of Th17 and Th1 cells. These effects were mediated through CB1 and CB2 receptors inasmuch as, THC+CBD failed to ameliorate EAE in mice deficient in CB1 and CB2. THC+CBD treatment also caused a decrease in the levels of brain infiltrating CD4+ T cells and pro-inflammatory molecules (IL-17, INF-γ, TNF-α, IL-1β, IL-6, and TBX21), while increasing anti-inflammatory phenotype such as FoxP3, STAT5b, IL-4, IL-10, and TGF-β. Also, the brain-derived cells showed increased apoptosis along with decreased percentage in G0/G1 phase with increased percentage in G2/M phase of cell cycle. miRNA microarray analysis of brain-derived CD4+ T cells revealed that THC+CBD treatment significantly down-regulated miR-21a-5p, miR-31-5p, miR-122-5p, miR-146a-5p, miR-150-5p, miR-155-5p, and miR-27b-5p while upregulating miR-706-5p and miR-7116. Pathway analysis showed that majority of the down-regulated miRs targeted molecules involved in cycle arrest and apoptosis such as CDKN2A, BCL2L11, and CCNG1, as well as anti-inflammatory molecules such as SOCS1 and FoxP3. Additionally, transfection studies involving miR-21 and use of Mir21-/- mice suggested that while this miR plays a critical role in EAE, additional miRs may also be involved in THC+CBD-mediated attenuation of EAE. Collectively, this study suggests that combination of THC+CBD suppresses neuroinflammation and attenuates clinical EAE development and that this effect is associated with changes in miRNA profile in brain-infiltrating cells.

Cannabinoid Receptor 1 Blockade Attenuates Obesity and Adipose Tissue Type 1 Inflammation Through miR-30e-5p Regulation of Delta-Like-4 in Macrophages and Consequently Downregulation of Th1 Cells

Obesity is characterized by chronic low-grade inflammation that contributes to development of cardiometabolic disorders. Cannabinoid receptor 1 (CB1) antagonists attenuate diet-induced obesity (DIO) and related inflammation, although the precise anti-inflammatory mechanisms involved have not been fully explored. In the current study we used a mouse model of DIO intervention to determine the microRNA (miRNA, miR)-mediated anti-obesity and anti-inflammatory effects of the CB1 antagonist, AM251. DIO mice that were fed high-fat diet (HFD) for 12 weeks were treated with AM251 (10 mg/kg) for an additional 4 weeks. HFD + AM251 mice experienced rapid and prolonged weight loss and reduced inflammatory M1 adipose tissue macrophage (ATM) infiltration. To investigate miRNA-mediated regulation of ATMs, F4/80+ cells from stromal vascular fractions (SVF) of epididymal fat were subjected to miR microarray analysis. Several miRs were differentially expressed in AM251-treated mice that were independent of calorie restriction. Prominently, miR-30e-5p was upregulated in ATMs from HFD + AM251 mice while the miR-30e-5p target, DLL4, was downregulated. Consistent with a decrease in DLL4-Notch signaling, fat storage and pro-inflammatory cytokine/chemokine expression was reduced following AM251 treatment. Furthermore, we found that AM251-treated macrophages can suppress DLL4-mediated Th1 polarization in CD4+ T cells. Together these data demonstrate that blocking CB1 receptors leads to upregulation of miR-30e-5p and down regulation of DLL4 in ATMs, which in turn suppress DLL4-Notch signaling-induced polarization of inflammatory Th1 cells and adipocyte energy storage. This combined effect of ATMs and T cells leads to an anti-inflammatory state and attenuation of DIO. These data support therapeutic potential of miR-30 in the treatment of cardiometabolic disorders.

Protective effect of resveratrol on the integrity of alveolar and intestinal epithelial barrier in SEB-induced acute lung injury

Acute lung injury (ALI) is a state of inflammation that breaks down the lung endothelial and epithelial cell barriers. In the current study, we investigated the role of resveratrol (RES) in regulating the expression and functions of tight junction proteins (TJP) in epithelial cell responses following exposure to this superantigen. To this end, C3H mice were given resveratrol orally twice prior to intranasal challenge with lethal SEB doses. 16S rRNA results showed that there were microbes transported in the blood in addition to the lung and colonic tissues. For this purpose, we used a reporter E. coli-GFP labeled bacterium to monitor and examine the viability of this bacterium in case of leak from lung into blood and other body compartments during the peak of ALI. The flow cytometry results showed significant reduction in copy numbers of this reporter in the blood in RES-treated mice in comparison to vehicle-treated mice. However, bacteriological examination for viability by culture of the blood showed all were negative for all experimental groups. Mouse transcriptome array showed increase in TJP gene expression in colonic and alveolar epithelial cells of RES-treated mice. Some of these genes were validated with qPCR. We found that there was an increase in the expression of some TJP genes following RES treatment. Commensals and probiotics are also known to decrease intestinal barrier dysfunction caused by inflammatory cytokines. Therefore, mass spectrometry (MS) analysis showed increase in the metabolome in colons of RES-treated group that help in strengthening of intestinal barrier. In conclusion, RES treatment increased directly or indirectly the rigidity of cell boundaries resulting in amelioration of ALI-dependent complications.

Indole-3-carbinol prevents murine colitis development via an IL-22-dependent mechanism that regulates anti-microbial peptides and mucus production

Colitis is an inflammatory bowel disease characterized by acute or chronic inflammation within the colon. In our previous work, we showed that indole-3-carbinol (I3C), a naturally-occurring plant product found in a number of cruciferous vegetables, was able to prevent development of colitis in murine models. I3C prevented colitis-associated microbial dysbiosis characterized by an overabundance of potentially pathogenic gram-negative bacteria (e.g. Bacteroides acidifaciens), in addition to increasing anti-inflammatory gram-positive butyrate-producing species (e.g. Roseburia). This increase in butyrate by I3C, validated by metabolomics analysis, leads to a decrease in the pro-inflammatory T cell response (Th17) and an increase in anti-inflammatory Tregs, which was confirmed by sodium butyrate supplementation experiments. In the current study, we further defined the mechanisms by which I3C was able to prevent colitis-associated microbial dysbiosis and dysregulation of gut microbial metabolome by evaluating expression of key intestinal regulatory genes in immune cells and colonic epithelial cells (CECs). Transcriptome analysis and PCR validation of CECs showed mucus production (e.g. Muc2) and colonic anti-microbial peptides (e.g. beta-defensins) were significantly increased after I3C. I3C was also shown to, in a butyrate-independent manner, increase expression of colonic bacterial defensive interleukin-22 (IL-22) by epigenetic regulation. Lastly, in vivo IL-22 neutralization experiments negated the beneficial effects of I3C, thus proving this cytokine was crucial in I3C-mediated prevention of colitis development and regulation of key intestinal regulatory components such as mucus and AMP production.

Cannabinoids decrease intestinal permeability and induce colonic CD103+ dendritic cells to increase T regulatory cells leading to decreased murine colitis-associated colon cancer

Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are two abundant phytocannabinoids found in Cannabis sativa. Cannabinoids bind to cannabinoid receptors 1 and 2 (CB1 and CB2), located primarily on the neurons and immune cells, respectively. Cannabis and synthetic THC and CBD are quickly gaining attention for their therapeutic potential in diseases ranging from epilepsy to multiple sclerosis, and cancer pain.

Colon cancer is the third leading cause of cancer-related deaths, and treatment options are limited to surgery, chemotherapy or radiation. Many physicians are now moving towards a strategy focused on prevention. Chronic inflammation is a cause of many cancers including colon cancer. Thus, we used a murine model of colitis induced colon cancer, wherein BL6 mice were given a single administration of carcinogen (azoxymethane) followed by DSS (1%) in the drinking water daily for 1 week followed by 2 weeks without DSS. This cycle, along with bi-weekly treatment with cannabinoids (CBD, THC, THC+CBD, or vehicle; all 10mg/kg; by oral gavage) continued for 10 weeks, as the progression of cancer was monitored.

Our data revealed that treatment with THC and THC+CBD resulted in decreased polyp formation in mice with colon cancer. We also showed that cannabinoids increased CD103+ dendritic cells in the colonic lamina propria that led to an increase in the CD4+Nrp1+FoxP3+ T regulatory cells (nTregs), which was dependent on CB2. Cannabinoids also increased the colonic barrier integrity as assessed by increased levels of ZO-1, through CB1, and increased mucus production. These changes collectively demonstrated cannabinoid treatment reduced the incidence of colitis-associated colon cancer by inducing an anti-inflammatory response.

Inflammation in PTSD is a consequence of dysregulated WNT signaling orchestrated by long non-coding RNA LINC00926 and lysine methyltransferase MLL1

Posttraumatic Stress Disorder patients experience chronic inflammation. It is not known whether immune dysregulation causes PTSD or the psychiatric imbalance occurs first. Moreover, little is known about the molecular mechanisms involved in the immune dysregulation. Our past work indicates the involvement of epigenetic mechanisms such as histone methylation in the regulation of inflammation in PTSD. By employing RNA-Seq, we identified upregulated expression of WNT10B and LINC00926 in the PBMCs of PTSD. Thus, we hypothesized that LINC00926 overexpression in PTSD results in increased H3K4me3 (gene activating histone methylation) around the promoter of WNT10B leading to its upregulation which in turn, regulated the elevated expression of inflammatory cytokines like IFNg and IL17. Thus, we first confirmed the interaction between LINC00926 and the histone H3K4 methyltransferase, MLL1. Then, by in vitro knockdown of LINC00926 we confirmed lowered expression of WNT10B implying that the interaction between LINC00926 and MLL1 possibly leads to increased H3K4me3 on WNT10B promoter and thereby its upregulation. Following this, we confirmed increased H3K4me3 around WNT10B promotor of PTSD patients by ChIP-Seq. Finally, we confirmed that upregulated WNT10B indeed contributed to the elevated expression of IFNg and IL17. In conclusion, our data implies that upregulation of LINC00926 in PTSD leads to inflammatory state by a mechanism that involves interaction with MLL1 resulting in increased H3K4me3 around WNT10B promotor and, eventually leads to elevated expression of proinflammatory cytokines. Our report is the first to show that inflammation in PTSD is a result of altered epigenetic mechanism involving LINC00926 and WNT10B.

Cannabinoid receptor 1 blockade attenuates obesity and adipose tissue type 1 inflammation through miR-30e-5p regulation of Delta-like-4

Obesity is characterized by chronic low-grade inflammation that contributes to development of cardiometabolic disorders. Cannabinoid receptor 1 (CB1) antagonists attenuate diet-induced obesity (DIO) and related inflammation, although the precise anti-inflammatory mechanisms involved have not been fully explored. In the current study we used a mouse model of DIO intervention to determine the microRNA (miR)-mediated anti-obesity and anti-inflammatory effects of the CB1 antagonist AM251. DIO mice that were fed high-fat diet (HFD) for 12 weeks were treated with AM251 (10mg/kg) for an additional four weeks. HFD+AM251 mice experienced rapid and prolonged weight loss and reduced inflammatory M1 adipose tissue macrophage (ATM) infiltration. To investigate miRNA-mediated regulation of ATMs, F4/80+ cells from stromal vascular fractions of epididymal fat were subjected to miR microarray analysis. Several miRs were differentially expressed in AM251-treated mice that were independent of calorie restriction. Prominently, miR-30e-5p was upregulated in ATMs from HFD+AM251 mice while the miR-30e-5p targeting DLL4 was downregulated. Consistent with a decrease in DLL4-Notch signaling, fat storage and pro-inflammatory cytokine/chemokine expression was reduced following AM251 treatment. Furthermore, we demonstrate that AM251-treated macrophages can suppress DLL4-mediated Th1 polarization in CD4+ T cells. Together these data indicate that weight-loss due to AM251 treatment mediates anti-inflammatory effects and amelioration of obesity through miR-30e-5p regulation of DLL4-Notch signaling-induced type 1 inflammation. These data support therapeutic potential of miR-30 in the treatment of cardiometabolic disorders.

Role of microRNA in CB1 antagonist-mediated regulation of adipose tissue macrophage polarization and chemotaxis during diet-induced obesity

Although cannabinoid receptor 1 (CB1) antagonists have been shown to attenuate diet-induced obesity (DIO) and associated inflammation, the precise molecular mechanisms involved are not clear. In the current study, we investigated the role of microRNA (miR) in the regulation of adipose tissue macrophage (ATM) phenotype following treatment of DIO mice with the CB1 antagonist SR141716A. DIO mice were fed high-fat diet (HFD) for 12 weeks and then treated daily with SR141716A (10 mg/kg) for 4 weeks while continuing HFD. Treated mice experienced weight loss, persistent reduction in fat mass, improvements in metabolic profile, and decreased adipose inflammation. CB1 blockade resulted in down-regulation of several miRs in ATMs, including the miR-466 family and miR-762. Reduced expression of the miR-466 family led to induction of anti-inflammatory M2 transcription factors KLF4 and STAT6, whereas down-regulation of miR-762 promoted induction of AGAP-2, a negative regulator of the neuroimmune retention cues, Netrin-1 and its coreceptor UNC5B. Furthermore, treatment of primary macrophages with SR141716A up-regulated KLF4 and STAT6, reduced secretion of Netrin-1, and increased migration toward the lymph node chemoattractant CCL19. These studies demonstrate for the first time that CB1 receptor blockade attenuates DIO-associated inflammation through alterations in ATM miR expression that promote M2 ATM polarization and macrophage egress from adipose tissue. The current study also identifies additional novel therapeutic targets for diet-induced obesity and metabolic disorder.

Resveratrol modulates the gut microbiota to prevent murine colitis development through induction of Tregs and suppression of Th17 cells

Inflammatory diseases of the gastrointestinal tract are often associated with microbial dysbiosis. Thus, dietary interactions with intestinal microbiota, to maintain homeostasis, play a crucial role in regulation of clinical disorders such as colitis. In the current study, we investigated if resveratrol, a polyphenol found in a variety of foods and beverages, would reverse microbial dysbiosis induced during colitis. Administration of resveratrol attenuated colonic inflammation and clinical symptoms in the murine model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis. Resveratrol treatment in mice with colitis led to an increase in CD4⁺ FOXP3⁺ and CD4⁺ IL-10⁺ T cells, and a decrease in CD4⁺ IFN-γ⁺ and CD4⁺ IL-17⁺ T cells. 16S rRNA gene sequencing to investigate alterations in the gut microbiota revealed that TNBS caused significant dysbiosis, which was reversed following resveratrol treatment. Analysis of cecal flush revealed that TNBS administration led to an increase in species such as Bacteroides acidifaciens, but decrease in species such as Ruminococcus gnavus and Akkermansia mucinphilia, as well as a decrease in SCFA i-butyric acid. However, resveratrol treatment restored the gut bacteria back to homeostatic levels, and increased production of i-butyric acid. Fecal transfer experiments confirmed the protective role of resveratrol-induced microbiota against colitis inasmuch as such recipient mice were more resistant to TNBS-colitis and exhibited polarization toward CD4⁺ FOXP3⁺ T cells and decreases in CD4⁺ IFN-γ⁺ and CD4⁺ IL-17⁺ T cells. Collectively, these data demonstrate that resveratrol-mediated attenuation of colitis results from reversal of microbial dysbiosis induced during colitis and such microbiota protect the host from colonic inflammation by inducing Tregs while suppressing inflammatory Th1/Th17 cells.

Evaluation of Cell Proliferation and Apoptosis in Immunotoxicity Testing

Immunotoxicity testing is important in determining the toxic effects of various chemicals on the immune system. The immune system is a direct target of numerous toxicants, and the adverse effects include serious health complications such as susceptibility to infections, cancer, allergic reactions, and autoimmune diseases. One way to investigate the harmful effects of different chemicals is to study apoptosis and/or proliferation in immune cells. Apoptosis is defined as programmed cell death, and in general, this process helps in development and maintenance of tolerance and homeostasis. However, in the case of an insult by a toxicant, enhanced apoptosis of immune cells may cause immunosuppression resulting in the development of cancer and the inability to fight infections. Apoptosis is characterized by cell shrinkage, nuclear condensation, changes in cell membrane and mitochondria, DNA fragmentation, and protein degradation by caspases. Various methods are employed to investigate apoptosis, including direct measurement of apoptotic cells with flow cytometry and in situ labeling, as well as RNA, DNA, and protein assays that are indicative of apoptotic molecules. In addition to apoptosis, quantification of cell proliferation can provide important additional information about the effect of a toxicant upon various immune cell populations. In some cases, a toxicant may act as a mitogen pushing the immune cell into the different stages of the cell cycle. There are four stages of the active cell cycle: G1, S, G2, and M, with cell division occurring in M stage. Proliferation can be quantified by numerous methods, including staining with ki-67 or CFSE, BrdU labeling, MTT assay, and/or ATP quantification.

Role of miRNA in the regulation of cannabidiol-mediated apoptosis in neuroblastoma cells

Neuroblastoma (NBL) is one of the most common childhood cancers that originate from the immature nerve cells of the sympathetic system. Studies with NBL cancers have also shown that miRNAs are dysregulated and may play a critical role in pathogenesis. Cannabidiol (CBD) is a non-psychoactive compound found in marijuana which has been previously shown by our laboratory and others to induce apoptosis in cancer cells. However, there are no studies reported to test if CBD mediates these effects through regulation of miRNA. In the current study, therefore, we investigated if CBD induces apoptosis in human NBL cell lines, SH SY5Y and IMR-32, and if it is regulated by miRNA. Our data demonstrated that CBD induces apoptosis in NBL cells through activation of serotonin and vanilloid receptors. We also found that caspase-2 and -3 played an important role in the induction of apoptosis. CBD also significantly reduced NBL cell migration and invasion in vitro. Furthermore, CBD blocked mitochondrial respiration and caused a shift in metabolism towards glycolysis. CBD altered the expression of miRNA specifically, down-regulating hsa-let-7a and upregulating hsa-mir-1972. Downregulation of let-7a increased expression of target caspase-3, and growth arrest specific-7 (GAS-7) genes. Upregulation of hsa-mir-1972 caused decreased expression of BCL2L1 and SIRT2 genes. Together, our studies suggest that CBD-mediated apoptosis in NBL cells is regulated by miRNA.

Role of MicroRNAs Induced by Chinese Herbal Medicines Against Hepatocellular Carcinoma: A Brief Review

MicroRNAs (miRNAs) are highly conserved, noncoding small RNAs that regulate gene expression, and consequently several important functions including early embryo development, cell cycle, programmed cell death, cell differentiation, and metabolism. While there are no effective treatments available against hepatocellular carcinoma (HCC), some Chinese herbal medicines have been shown to regulate growth, differentiation, invasion, and metastasis of HCC. Many studies have shown that Chinese herbal medicines regulate the expression of miRNAs and this may be associated with their ability to control the development of HCC. In this article, the effects of Chinese herbal medicines on the expression of miRNAs and their functions in the regulation of HCC have been reviewed and discussed. miRNAs such as miRNA-221 and miRNA-222 mediated by Chinese herbal medicines may be good biomarkers and therapeutic targets for HCC.

Cannabidiol Attenuates Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis Through Induction of Myeloid-Derived Suppressor Cells

Multiple sclerosis (MS) is a chronic debilitating autoimmune disease without a cure. While the use of marijuana cannabinoids for MS has recently been approved in some countries, the precise mechanism of action leading to attenuate neuroinflammation is not clear. We used experimental autoimmune encephalomyelitis (EAE), a murine model of MS, to explore the anti-inflammatory properties of cannabidiol (CBD), a non-psychoactive cannabinoid. Treatment with CBD caused attenuation of EAE disease paradigms as indicated by a significant reduction in clinical scores of paralysis, decreased T cell infiltration in the central nervous system, and reduced levels of IL-17 and IFNγ. Interestingly, CBD treatment led to a profound increase in myeloid-derived suppressor cells (MDSCs) in EAE mice when compared to the vehicle-treated EAE controls. These MDSCs caused robust inhibition of MOG-induced proliferation of T cells in vitro. Moreover, adoptive transfer of CBD-induced MDSCs ameliorated EAE while MDSC depletion reversed the beneficial effects of CBD treatment, thereby conclusively demonstrating that MDSCs played a crucial role in CBD-mediated attenuation of EAE. Together, these studies demonstrate for the first time that CBD treatment may ameliorate EAE through induction of immunosuppressive MDSCs.

An endogenous aryl hydrocarbon receptor ligand, ITE, induces regulatory T cells and ameliorates experimental colitis

Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition that affects millions of people with high morbidity and health care costs. The precise etiology of IBD is unknown, but clear evidence suggests that intestinal inflammation is caused by an excessive immune response to mucosal antigens. Recent studies have shown that activation of the aryl hydrocarbon receptor (AhR) induces regulatory T cells (Tregs) and suppresses autoimmune diseases. In the current study, we investigated if a nontoxic ligand of AhR, 2-(1' H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), can attenuate dextran sodium sulfate-induced colitis. Our studies demonstrated that in mice that received ITE treatment in vivo, colitis pathogenesis, including a decrease in body weight, was significantly reversed along with the systemic and intestinal inflammatory cytokines. ITE increased the expression of Tregs in spleen, mesenteric lymph nodes (MLNs), and colon lamina propria lymphocytes (cLPL) of mice with colitis when compared with controls. This induction of Tregs was reversed by AhR antagonist treatment in vitro. ITE treatment also increased dendritic cells (CD11c⁺) and decreased macrophages (F4/80⁺) from the spleen, MLNs, and cLPL in mice with colitis. ITE also reversed the systemic and intestinal frequency of CD4⁺ T cells during colitis and suppressed inflammatory cytokines including IFN-γ, TNF-α, IL-17, IL-6, and IL-1 as well as induced IL-10 levels. These findings suggest that ITE attenuates colitis through induction of Tregs and reduction in inflammatory CD4⁺ T cells and cytokines. Therefore, our work demonstrates that the nontoxic endogenous AhR ligand ITE may serve as a therapeutic modality to treat IBD. NEW & NOTEWORTHY We report the novel finding that activation of the aryl hydrocarbon receptor with the nontoxic ligand 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE) induces regulatory T cells (Tregs) and suppresses inflammatory bowel disease (IBD). Our data suggest that ITE diminishes colitis pathology through induction of Tregs; reduces inflammatory cytokines, inflammation score, and macrophage frequency; and induces DCs resulting in amelioration of colitis. Therefore, nontoxic endogenous ITE promotes the induction of Tregs and may be useful for the treatment of IBD.

Genistein induces macrophage polarization and systemic cytokine to ameliorate experimental colitis

Mucosal changes in Crohn’s disease (CD) and ulcerative colitis (UC), two major forms of inflammatory bowel disease (IBD), are characterized by a prominent infiltration of inflammatory cells including lymphocytes, macrophages, T cells and neutrophils. The precise etiology of IBD is unknown but it involves a complex interplay of factors associated with the immune system, environment, host genotype and enteric commensal bacteria. As there is no known safe cure for IBD, natural alternative therapeutic options without side effects are urgently needed. To this end, Soy-based foods, which have been eaten for centuries in Asian countries, have potential benefits, including lowering the incidence of coronary heart disease, atherosclerosis, type-2 diabetes, allergic response, and autoimmune diseases. This study describes the effect of Soy isoflavons 4', 5, 7 Trihydroxyisoflavone (genistein) on dextran sodium sulphate (DSS) induced experimental colitis. The extent and severity of disease was analyzed through body weight, histopathological analysis, cellular immune response, systemic cytokine levels, and inflammation score using a disease activity index. Genistein treatment significantly attenuated DSS-induced colitis severity and resulted in increase in body weight, colon length and reduction in inflammation score. Genistein also skews M1 macrophages towards the M2 phenotype. Further, gen also reduced the systemic cytokine levels as compared to vehicle control. This serves as the first detailed study towards natural soya based product that shows the polarization of M1 towards M2 macrophages, and reduction of systemic cytokine in part to attenuate the colitis symptoms. Thus, our work demonstrates that genistein, a soya compound, may be useful for the treatment of IBD.

MicroRNA-30 modulates metabolic inflammation by regulating Notch signaling in adipose tissue macrophages

Background/Objectives

Obesity is a pandemic disorder that is characterized by accumulation of adipose tissue and chronic-low grade inflammation that is driven primarily by adipose tissue macrophages (ATMs). While ATM polarization from pro-(M1)to anti-(M2) inflammatory phenotype influences insulin sensitivity and energy expenditure, the mechanisms of such a switch are unclear. In the current study we identified epigenetic pathways including microRNAs (miR) in ATMs that regulate obesity-induced inflammation.

Subjects/Methods

Male C57BL/6J mice were fed normal chow diet (NCD) or high-fat diet (HFD) for 16 weeks to develop lean and diet-induced obese mice respectively. Transcriptome microarrays, microRNA microarrays, and meDIP-Seq were performed on ATMs isolated from visceral fat. Pathway analysis and bone marrow derived macrophage (BMDM) transfections further allowed computational and functional analysis of miRNA-mediated ATM polarization.

Results

ATMs from HFD-fed mice were skewed towards M1 inflammatory phenotype. Concurrently, the expression of miRs 30a-5p, 30c-5p, and 30e-5p was downregulated in ATMs from HFD mice when compared to mice fed NCD. The miR-30 family was shown to target Delta-like-4, a Notch1 ligand, whose expression was increased in HFD ATMs. Inhibition of miR-30 in conditioned BMDM triggered Notch1 signaling, pro-inflammatory cytokine production, and M1 macrophage polarization. In addition, DNA hypermethylation was observed in mir30-associated CpG islands suggesting HFD downregulates miR-30 through epigenetic modifications.

Conclusions

HFD-induced obesity downregulates miR-30 by DNA methylation thereby inducing Notch1 signaling in ATMs and their polarization to M1 macrophages. These findings identify miR-30 as a regulator of pro-inflammatory ATM polarization and suggest miR-30 manipulation could be a therapeutic target for obesity-induced inflammation.

MicroRNA-92 expression in CD133+ melanoma stem cells regulates immunosuppression in the tumor microenvironment through integrin-dependent TGF-β activation

The existence of cancer stem cells (CSC) accounts for the high degree of chemoresistance and heterogeneity characterizing refractory melanomas. Yet, the degree to which CSCs modulate immune cells in the tumor microenvironment has yet to be revealed. The present study aims to establish a novel role for miR-92 and its associated gene networks in immunomodulation. We employed syngeneic mouse models utilizing B16-F10 melanoma cells to observe primary tumor and metastatic growth. CSCs were isolated from the parental line based on expression of the putative CSC marker, CD133. CD133+ cells were functionally distinct from CD133− cells with CD133+ cells showing increased proliferation in vitro and enhanced tumorigenesis when administered subcutaneously. Our data indicated that compared to CD133− cells, CD133+ CSCs had a greater capacity to recruit immunosuppressive cell types during tumor formation. Using microarray technology in order to expose disparities in microRNA expression between CSC and non-CSC compartments, we identified several miRs that were significantly downregulated in CD133+ cells including miR-92. We hypothesized that lower levels of miR-92 in CSCs led to higher expression of integrin subunits as predicted by gene alignment software and confirmed using qRT-PCR. Flow cytometry analysis of dissociated tumors demonstrated that tumors initiated by CD133+ cells displayed significantly higher levels of TGF-β compared to CD133− cells. Additionally, qRT-PCR for TGF-β associated genes confirmed a significant increase in expression in CD133+ cells. These data suggest that CSCs efficiently induce intratumoral immunosuppression which is potentially regulated by a miR-92 driven axis involving integrin activation of TGF-β.

Enterohepatic Helicobacter species modulate severity of DSS-induced colitis but do not prevent amelioration by indole-3-carbinol

Enterohepatic Helicobacter (EHH) species are bacteria that colonize the colons and biliary ducts of humans and other mammals. Virtually nothing is known about the mechanisms of EHH-induced colitis in wild-type mice or humans. Indole-3-carbinol (I3C), a chemical extracted from cruciferous vegetables, ameliorates Dextran sulfate sodium (DSS)-induced colitis. We hypothesized that specific EHH species would alter the course of DSS-induced colitis and possibly the responses to I3C treatment. We infected C57BL/6 mice with human- and rodent-associated EHH species and measured the effects on DSS-induced colitis and response to I3C treatment. We found that H. muridarum(H.m) and H. cinaedi exacerbate DSS-induced colitis and delay recovery. Furthermore, I3C ameliorated colitis and shifted the Treg/Th17 balance in H.m-infected mice. Moreover, the microRNAs expression pattern was altered in H.m-infected mice when compared to that of uninfected mice. Interestingly, enhanced colitis, as well as increased Th17 cells in spleens and mesenteric lymph nodes, were observed in H.m-infected DSS-treated mice(DHM). I3C treatment of DSS + H.m-infected mice (DMI) decreased the expression of pro-inflammatory IL17 and RORC as well as increased anti-inflammatory Foxp3 when compared to DHM group. These immunological changes correlated with the microRNAs expression. This demonstrates that the presence of EHH species alters susceptibility to DSS-induced colitis. Importantly, mice with exacerbated colitis respond to I3C. In the future, we plan to study the mechanisms underlying the effects of EHH on colon cancer development and the efficacy of I3C in both the colitis and colon cancer models.

Cannabinoid receptor 1 blockade attenuates metabolic inflammation and gut microbial dysbiosis during high-fat diet-induced obesity

The endocannabinoid (eCB) system regulates a variety of physiological processes including inflammation and metabolism. Obesity is characterized by overactivation of the eCB system, chronic low-grade inflammation, metabolic dysfunction, and gut microbial dysbiosis. Blockade of cannabinoid receptor 1 (CB1) ameliorates obesity, however CB1-mediated immune-microbial interactions have not been extensively explored. In the current study, antagonists and genetic ablation of CB1 were used in a mouse model of diet-induced obesity to determine the role of CB1 in modulating inflammation, metabolism, and the gut microbiome. As expected, CB1−/− mice were resistant to high-fat diet (HFD)-induced weight gain and metabolic inflammation was significantly less in CB1−/− mice when compared to wild-type (WT) controls. Lamina propria lymphocytes from CB1−/− mice did not display a Th1 induction after HFD feeding whereas WT mice fed HFD had elevated CD4+T-bet+ cells compared to WT mice fed low-fat diet. Decreased colonic inflammation indicated CB1-dependent alterations in the gut microbiome may contribute to a decreased obese phenotype. Similarly, WT obese mice treated with the CB1 antagonist AM251 experienced weight loss, decreased inflammation, and improvement in metabolic parameters. Interrogation of the gut microbiome by 16S metagenomics revealed CB1-dependent alterations in abundance of bacteria belonging to the Clostridiales order. In addition, functional predictions by PICRUSt analysis revealed decreased abundance of operational taxonomic units belonging to bacterial metabolism and membrane transport pathways. Together these data suggest CB1 regulates metabolism by shaping the immune response and gut microbial community.

Marijuana THC treatment led to decreased metabolic functions of Staphylococcal enterotoxin B-activated lymphocytes

Studies from our laboratory have shown that Δ9-Tetrahydrocannabinol (THC), an ingredient found in marijuana plant Cannabis sativa, can attenuate acute lung injury induced by Staphylococcus enterotoxin B (SEB). In the current study, we investigated the role of THC on the metabolism of SEB-activated lymphocytes. To this end, we determined metabolic potential of SEB-activated lymphocytes treated with vehicle or THC by performing the Cell Mito Stress Test. The oxygen consumption rate (OCR) in THC-treated cells was decreased when compared to vehicle-treated group whereas the extracellular acidification rate (ECAR) was similar in both the groups. Specifically, electron transport chain inhibitors namely, oligomycin, FCCP and rotenone+antimycinA were added to measure ATP-linked respiration, maximal respiration and non-mitochondrial respiration, respectively. THC treatment led to a significant decrease in the basal respiration, ATP production, proton (H+) leak, maximal respiration, spare respiratory capacity and nonmitochondrial respiration. We also performed the Mito Fuel Flex assay to measure the dependency, capacity and flexibility of cells to oxidize glucose, glutamine and fatty acids. Treatment with inhibitors, BPTES and etomoxir showed a decline in the OCR in SEB+vehicle treated cells demonstrating that glutamine and/or fatty acids serve as major source of fuel in these cells when compared to SEB+THC treated group. However, when UK5099 was added, THC- and vehicle-treated cells showed a reduced response thereby indicating that glucose dependency was similar in both the groups. Together, THC modulates metabolic functions of activated lymphocytes which may affect their signaling, differentiation and toxicity.

Macrophage depletion results in anemia, neutrophilia, and is not an effective therapy for rescuing obesity-linked metabolic impairments

Low-grade, chronic inflammation is thought to play a role in obesity-associated metabolic dysfunction. In obesity, macrophages account for approximately 50% of adipose tissue cells and can secrete a variety of proinflammatory cytokines. In this study, we sought to deplete macrophages in order to decrease macrophage-mediated inflammation and rescue metabolic dysfunction. Following 16 weeks of high-fat diet (HFD) (40% of total kcal from fat) or AIN-76A control diet consumption (n=30), male C57BL/6J mice within each diet cohort were assigned to either a clodronate (CLD)-liposome or PBS-liposome-treatment (n=15/group). Mice received 200 μl (1mg) i.p. injections of CLD or PBS-encapsulated liposomes (control group) twice weekly for 4 weeks to deplete macrophages. Metabolic function was assessed via the HOMA-IR, glucose and insulin tolerance tests, and serum free fatty acids. Adipose tissue, liver, and blood were analyzed for macrophage infiltration, inflammatory mediators and circulating cell populations. HFD-fed mice exhibited an obese phenotype compared to the control diet; however, macrophage depletion was unable to rescue metabolic dysfunction. Interestingly, macrophage-depleted mice had >35% increase in circulating neutrophils and adipose tissue Ly6G content. The increase in neutrophils, likely a compensation for the depletion of macrophages, was linked to an increase in the proinflammatory cytokines, IL-6 and IL1β, in the adipose tissue. Additionally, the decrease in macrophages resulted in iron-deficient anemia. Our study suggests that depleting macrophages in an obese setting is not an effective therapy for rescuing metabolic dysfunction and may increase the risk for anemia and adipose tissue inflammation.