Platelet activating factor receptor acts to limit colitis-induced liver inflammation

Pomegranate seed oil mitigates liver and kidney damage in an experimental colitis model: Modulation of NF-κB activation and apoptosis

Pomegranate seed oil, extracted from pomegranate seeds, is a slightly fragrant yellow oil with a mild odor. Pomegranate seed oil is the main source of punicic acid (conjugated linolenic acid). Punicic acid is a long-chain omega-5 polyunsaturated fatty acid and a conjugated α-linolenic acid molecule. This acid is thought to provide many health benefits. This study evaluated the potential of pomegranate seed oil to attenuate damage to liver and kidney tissues in an acetic acid-induced colitis model. 32 male Sprague-Dawley rats were divided into 4 groups: control, colitis, 0.4 ml/kg, and 0.8 ml/kg pomegranate seed oil treatment after colitis. At the end of the experiment, histopathological and immunohistochemistry analyses of liver and kidney tissues were performed. Pomegranate seed oil treatment reduced damage in liver and kidney tissues, suppressed NF-κB activation, and regulated apoptosis. These findings support the potential effects of pomegranate seed oil against extraintestinal symptoms of colitis through its anti-inflammatory, and anti-apoptotic properties.

The relationship between extreme inter-individual variation in macrophage gene expression and genetic susceptibility to inflammatory bowel disease

The differentiation of resident intestinal macrophages from blood monocytes depends upon signals from the macrophage colony-stimulating factor receptor (CSF1R). Analysis of genome-wide association studies (GWAS) indicates that dysregulation of macrophage differentiation and response to microorganisms contributes to susceptibility to chronic inflammatory bowel disease (IBD). Here, we analyzed transcriptomic variation in monocyte-derived macrophages (MDM) from affected and unaffected sib pairs/trios from 22 IBD families and 6 healthy controls. Transcriptional network analysis of the data revealed no overall or inter-sib distinction between affected and unaffected individuals in basal gene expression or the temporal response to lipopolysaccharide (LPS). However, the basal or LPS-inducible expression of individual genes varied independently by as much as 100-fold between subjects. Extreme independent variation in the expression of pairs of HLA-associated transcripts (HLA-B/C, HLA-A/F and HLA-DRB1/DRB5) in macrophages was associated with HLA genotype. Correlation analysis indicated the downstream impacts of variation in the immediate early response to LPS. For example, variation in early expression of IL1B was significantly associated with local SNV genotype and with subsequent peak expression of target genes including IL23A, CXCL1, CXCL3, CXCL8 and NLRP3. Similarly, variation in early IFNB1 expression was correlated with subsequent expression of IFN target genes. Our results support the view that gene-specific dysregulation in macrophage adaptation to the intestinal milieu is associated with genetic susceptibility to IBD.

Intestinal Inflammation and Regeneration-Interdigitating Processes Controlled by Dietary Lipids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a disease of chronic inflammatory conditions of the intestinal tract due to disturbance of the inflammation and immune system. Symptoms of IBD include abdominal pain, diarrhea, bleeding, reduced weight, and fatigue. In IBD, the immune system attacks the intestinal tract's inner wall, causing chronic inflammation and tissue damage. In particular, interlukin-6 and interlukin-17 act on immune cells, including T cells and macrophages, to amplify the immune responses so that tissue damage and morphological changes occur. Of note, excessive calorie intake and obesity also affect the immune system due to inflammation caused by lipotoxicity and changes in lipids supply. Similarly, individuals with IBD have alterations in liver function after sustained high-fat diet feeding. In addition, excess dietary fat intake, along with alterations in primary and secondary bile acids in the colon, can affect the onset and progression of IBD because inflammatory cytokines contribute to insulin resistance; the factors include the release of inflammatory cytokines, oxidative stress, and changes in intestinal microflora, which may also contribute to disease progression. However, interfering with de novo fatty acid synthase by deleting the enzyme acetyl-CoA-carboxylase 1 in intestinal epithelial cells (IEC) leads to the deficiency of epithelial crypt structures and tissue regeneration, which seems to be due to Lgr5+ intestinal stem cell function. Thus, conflicting reports exist regarding high-fat diet effects on IBD animal models. This review will focus on the pathological basis of the link between dietary lipids intake and IBD and will cover the currently available pharmacological approaches.

TLR7 promotes smoke-induced experimental lung damage through the activity of mast cell tryptase

Toll-like receptor 7 (TLR7) is known for eliciting immunity against single-stranded RNA viruses, and is increased in both human and cigarette smoke (CS)-induced, experimental chronic obstructive pulmonary disease (COPD). Here we show that the severity of CS-induced emphysema and COPD is reduced in TLR7-deficient mice, while inhalation of imiquimod, a TLR7-agonist, induces emphysema without CS exposure. This imiquimod-induced emphysema is reduced in mice deficient in mast cell protease-6, or when wild-type mice are treated with the mast cell stabilizer, cromolyn. Furthermore, therapeutic treatment with anti-TLR7 monoclonal antibody suppresses CS-induced emphysema, experimental COPD and accumulation of pulmonary mast cells in mice. Lastly, TLR7 mRNA is increased in pre-existing datasets from patients with COPD, while TLR7+ mast cells are increased in COPD lungs and associated with severity of COPD. Our results thus support roles for TLR7 in mediating emphysema and COPD through mast cell activity, and may implicate TLR7 as a potential therapeutic target.

Activated Hepatic Nuclear Factor-κB in Experimental Colitis Regulates CYP2A5 and Metronidazole Disposition

Systemic exposure of metronidazole is increased in patients with inflammatory bowel diseases (IBDs), while the underlying mechanism remains unknown. Here, we aim to decipher the mechanisms by which experimental colitis regulates metronidazole disposition in mice. We first confirmed that the systemic exposure of metronidazole was elevated in dextran sulfate sodium (DSS)-induced experimental colitis. Hepatic microsomal incubation with metronidazole revealed that the production rate of 2-hydroxymetronidazole was inhibited, suggestive of a diminished hydroxylation reaction upon colitis. Remarkably, the hydroxylation reaction of metronidazole was selectively catalyzed by CYP2A5, which was downregulated in the liver of colitis mice. In addition, hepatic nuclear factor (NF)-κB (a prototypical and critical signaling pathway in inflammation) was activated in colitis mice. Luciferase reporter and chromatin immunoprecipitation assay indicated that NF-κB downregulated Cyp2a5 transcription through binding to an NF-κB binding site (-1711 to -1720 bp) in the promoter. We further verified that the regulatory effects of colitis on CYP2A5 depended on the disease itself rather than the DSS compound. First, one-day administration of DSS did not alter mRNA and protein levels of CYP2A5. Moreover, CYP2A5 was suppressed in the Il-10^-/- spontaneously developing colitis model. Furthermore, Cyp2a5 expression was downregulated in both groups of mice with modest or severe colitis, whereas the expression change was much more significant in severe colitis as compared to modest colitis. Altogether, activated hepatic NF-κB in experimental colitis regulates CYP2A5 and metronidazole disposition, revealing the mechanism of pharmacokinetic instability under IBDs, and providing a theoretical foundation for rational drug use in the future.

Dysregulated hepatic UDP-glucuronosyltransferases and flavonoids glucuronidation in experimental colitis

Glucuronidation catalyzed by UDP-glucuronosyltransferases (UGTs) is one of the most important phase II mechanisms, facilitating drug clearance via conjugation of glucuronic acid with polar groups of xenobiotics. Accumulating evidence suggests that IBDs impact drug disposition, but whether and how IBDs regulate UGTs and drug glucuronidation remains undefined. In this study, we aim to investigate the expression of UGTs and drug glucuronidation in experimental colitis. Given that glucuronidation occurs primarily in the liver, we analyzed the mRNA changes in hepatic UGTs with a DSS-induced mouse colitis model. Twelve UGTs were downregulated in the liver of colitis mice including UGT1A1 and UGT1A9 (two representative UGTs). Colitis in mice downregulated UGT1A1 and UGT1A9 in the liver but not in small intestine, colon, and kidney. We also established that the downregulation of UGTs was attributed to the disease itself rather than the DSS compound. Moreover, colitis-reduced UGT1A1 and UGT1A9 lead to dampened baicalein and puerarin glucuronidation. PXR was the only UGT regulator significantly downregulated in colitis mice, suggesting dysregulation of PXR is associated with the downregulation of UGT1A1 and UGT1A9, thereby potentially resulting in dysfunction of baicalein and puerarin glucuronidation. Collectively, we establish that UGTs and glucuronidation are dysregulated in colitis, and this effect may cause variation in drug responsiveness in IBDs.

Milk Fat Globule Membrane Attenuates Acute Colitis and Secondary Liver Injury by Improving the Mucus Barrier and Regulating the Gut Microbiota

Objective

Inflammatory bowel disease (IBD) often occurs along with extraintestinal manifestations, including hepatic injury. Milk fat globule membrane (MFGM) is an active substance with a potential anti-inflammation activity. However, its alleviated effect and mechanisms in IBD as well as the IBD-induced secondary liver injury are still unclear.

Methods

C57BL/6J mice were administered with a 21-day oral gavage of MFGM, followed by 7 days of drinking water with 4% dextran sulfate sodium (DSS). Disease activity index (DAI), histological features, and cytokines of the colon and liver were evaluated. Then, RNA-seq of the colon and liver was conducted. The gut microbiota was assessed by analyzing 16S rRNA gene sequences, and finally the integrity and the function of the mucus barrier were evaluated by Alcian blue staining, real-time quantitative PCR, and ELISA.

Results

Prophylactic MFGM treatment was effective against colitis to include effects in body weight loss, DAI score, colonic length, intestinal pathology, and histological score. Additionally, prophylactic MFGM decreased the levels of interleukin (IL)-1β, IL-6, and myeloperoxidase in colonic tissue, while it increased the IL-10 level. Moreover, the gene expressions of MUC2, MUC4, Reg3b, and Reg3g associated with the production of the molecular mediator of immune response, membrane invagination, and response to protozoan were strikingly upregulated when administered with MFGM. On the other hand, the beneficial effects of MFGM were related to the enriched abundance of genera such as Faccalibacumum and Roseburia in feces samples. Consistently, the administration of MFGM was also found to alleviate DSS-induced hepatic injury. Furthermore, the glutathione transferase activity pathway was enriched in the liver of MFGM-treated mice after DSS administration. Mechanistically, prophylactic MFGM enhanced the mucosal barrier by increasing the gene levels of Reg3b and Reg3g. Meanwhile, the alleviation of MFGM on liver injury was dependent on the reduced hepatic oxidative stress.

Conclusions

MFGM attenuated colitis and hepatic injury by maintaining the mucosal barrier and bacterial community while inhibiting oxidative stress, which might be an effective therapy of hepatic injury secondary to IBD.

Gallic Acid as a Non-Selective Inhibitor of α/β-Hydrolase Fold Enzymes Involved in the Inflammatory Process: The Two Sides of the Same Coin

(1) Background: Gallic acid (GA) has been characterized as an effective anti-inflammatory, antivenom, and promising drug for therapeutic use. (2/3) Methods and Results: GA was identified from ethanolic extract of fresh pitanga (Eugenia uniflora) leaves, which was identified using commercial GA. Commercial GA neutralized the enzymatic activity of secretory PLA2 (sPLA2) by inhibiting the active site and inducing changes in the secondary structure of the enzyme. Pharmacological edema assays showed that GA strongly decreased edema when the compound was previously incubated with sPLA2. However, prior treatment of GA (30 min before) significantly increased the edema and myotoxicity induced by sPLA2. The molecular docking results of GA with platelet-acetylhydrolase (PAF-AH) and acetylcholinesterase reveal that this compound was able to interact with the active site of both molecules, inhibiting the hydrolysis of platelet-activating factor (PAF) and acetylcholine (ACh). (4) Conclusion: GA has a great potential application; however, our results show that this compound can also induce adverse effects in previously treated animals. Additionally, the increased edema and myotoxicity observed experimentally in GA-treated animals may be due to the inhibition of PAF-AH and Acetylcholinesterase.

Loss of Hyaluronan and Proteoglycan Link Protein-1 Induces Tumorigenesis in Colorectal Cancer

Colorectal cancer (CRC) is the third most common diagnosed cancer worldwide, but there are no effective cures for it. Hyaluronan and proteoglycan link protein-1 (HAPLN1) is a component of the extracellular matrix (ECM) proteins and involved in the tumor environment in the colon. Transforming growth factor (TGF)-β is a key cytokine that regulates the deposition of ECM proteins in CRC. However, the role of HAPLN1 in TGF-β contributions to CRC remains unknown. We found that the mRNA expression of HAPLN1 was decreased in tumors from CRC patients compared with healthy controls and normal tissue adjacent to the tumor using two existing microarray datasets. This was validated at the protein level by tissue array from CRC patients (n = 59). HAPLN1 protein levels were also reduced in human CRC epithelial cells after 24 h of TGF-β stimulation, and its protein expression correlated with type I collagen alpha-1 (COL1A1) in CRC. Transfection of HAPLN1 overexpression plasmids into these cells increased protein levels but reduced COL1A1 protein, tumor growth, and cancer cell migration. TGF-β stimulation increased Smad2/3, p-Smad2/3, Smad4, and E-adhesion proteins; however, HAPLN1 overexpression restored these proteins to baseline levels in CRC epithelial cells after TGF-β stimulation. These findings suggest that HAPLN1 regulates the TGF-β signaling pathway to control collagen deposition via the TGF-β signaling pathway and mediates E-adhesion to control tumor growth. Thus, treatments that increase HAPLN1 levels may be a novel therapeutic option for CRC.

Antagonizing astrocytic platelet activating factor receptor-neuroinflammation for total flavone of epimedium in response to cuprizone demyelination

Demyelinating diseases of the central nervous system are characterized by recurrent demyelination and progressive neurodegeneration, but there are no clinical drugs targeting myelin regeneration or improving functional disability in the treatment of multiple sclerosis. Total flavone of Epimedium (TFE) is the main active components of Epimedium, which exhibits the beneficial biological activities in the treatment of diseases, but there is no report in the treatment of demyelinating disorder. The purpose of this study was to explore the therapeutic potential and possible mechanism of TFE in the treatment of demyelination. The results showed that TFE efficiently improved the behavioural performance and histological demyelination in cuprizone (CPZ)-induced demyelinating model. In terms of action, TFE increased astrocytes enrichment in corpus callosum, striatum and cortex, and promoted astrocytes to express neurotrophic factors. Furthermore, the expression of platelet-activating factor receptor (PAFR) in astrocytes was induced by CPZ feeding and LPS stimulation, accompanied by the increase of inflammatory cytokines TNF-α,IL-6 and IL-1β. TFE declined the expression of PAFR, and inhibited inflammatory response. At the same time, TFE also antagonized PAFR activation and inflammatory response triggered by PAF, which further confirmed that TFE, as a new PAFR antagonist, inhibited the astrocyte-derived inflammatory response by antagonizing PAFR-neuroinflammation axis, thus contributing to myelin protection and regeneration.

Therapeutic targets in lung tissue remodelling and fibrosis

Structural changes involving tissue remodelling and fibrosis are major features of many pulmonary diseases, including asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Abnormal deposition of extracellular matrix (ECM) proteins is a key factor in the development of tissue remodelling that results in symptoms and impaired lung function in these diseases. Tissue remodelling in the lungs is complex and differs between compartments. Some pathways are common but tissue remodelling around the airways and in the parenchyma have different morphologies. Hence it is critical to evaluate both common fibrotic pathways and those that are specific to different compartments; thereby expanding the understanding of the pathogenesis of fibrosis and remodelling in the airways and parenchyma in asthma, COPD and IPF with a view to developing therapeutic strategies for each. Here we review the current understanding of remodelling features and underlying mechanisms in these major respiratory diseases. The differences and similarities of remodelling are used to highlight potential common therapeutic targets and strategies. One central pathway in remodelling processes involves transforming growth factor (TGF)-β induced fibroblast activation and myofibroblast differentiation that increases ECM production. The current treatments and clinical trials targeting remodelling are described, as well as potential future directions. These endeavours are indicative of the renewed effort and optimism for drug discovery targeting tissue remodelling and fibrosis.

SARS-CoV-2 induces transcriptional signatures in human lung epithelial cells that promote lung fibrosis

BACKGROUND

Severe acute respiratory syndrome (SARS)-CoV-2-induced coronavirus disease-2019 (COVID-19) is a pandemic disease that affects > 2.8 million people worldwide, with numbers increasing dramatically daily. However, there is no specific treatment for COVID-19 and much remains unknown about this disease. Angiotensin-converting enzyme (ACE)2 is a cellular receptor of SARS-CoV-2. It is cleaved by type II transmembrane serine protease (TMPRSS)2 and disintegrin and metallopeptidase domain (ADAM)17 to assist viral entry into host cells. Clinically, SARS-CoV-2 infection may result in acute lung injury and lung fibrosis, but the underlying mechanisms of COVID-19 induced lung fibrosis are not fully understood.

METHODS

The networks of ACE2 and its interacting molecules were identified using bioinformatic methods. Their gene and protein expressions were measured in human epithelial cells after 24 h SARS-CoV-2 infection, or in existing datasets of lung fibrosis patients.

RESULTS

We confirmed the binding of SARS-CoV-2 and ACE2 by bioinformatic analysis. TMPRSS2, ADAM17, tissue inhibitor of metalloproteinase (TIMP)3, angiotensinogen (AGT), transformation growth factor beta (TGFB1), connective tissue growth factor (CTGF), vascular endothelial growth factor (VEGF) A and fibronectin (FN) were interacted with ACE2, and the mRNA and protein of these molecules were expressed in lung epithelial cells. SARS-CoV-2 infection increased ACE2, TGFB1, CTGF and FN1 mRNA that were drivers of lung fibrosis. These changes were also found in lung tissues from lung fibrosis patients.

CONCLUSIONS

Therefore, SARS-CoV-2 binds with ACE2 and activates fibrosis-related genes and processes to induce lung fibrosis.