New Insights into Inflammatory Bowel Diseases from Proteomic and Lipidomic Studies

Cassane diterpenoid ameliorates dextran sulfate sodium-induced experimental colitis by regulating gut microbiota and suppressing tryptophan metabolism

Ulcerative colitis (UC) is one form of inflammatory bowel disease (IBD), characterized by chronic relapsing intestinal inflammation. As increasing morbidity of UC and deficiency of conventional therapies, there is an urgent need for attractive treatment. Cassane diterpenoids, the characteristic chemical constituents of Caesalpinia genus plants, have been studied extensively owing to various and prominent biological activities. This study attempted to investigate the bioactivity of caesaldekarin e (CA), a cassane diterpenoid isolated from C. bonduc in our previous work, on dextran sulfate sodium (DSS)-induced experimental colitis and clarify the function mechanism. The results indicated that CA ameliorated mice colitis by relieving disease symptoms, suppressing inflammatory infiltration and maintaining intestinal barrier integrity. Furthermore, 16S rRNA gene sequencing analysis indicated that CA could improve the gut microbiota imbalance disrupted by DSS and especially restored abundance of Lactobacillus. In addition, untargeted metabolomics analysis suggested that CA regulated metabolism and particularly the tryptophan metabolism by inhibiting the upregulation of indoleamine 2,3-dioxygenase 1 (IDO-1). It also been proved in IFN-γ induced RAW264.7 cells. Overall, this study suggests that CA exhibits anti-UC effect through restoring gut microbiota and regulating tryptophan metabolism and has the potential to be a treatment option for UC.

Proteomic and lipidomic biomarkers in the diagnosis and progression of inflammatory bowel disease - a review

PURPOSE

There is an increasing prevalence of inflammatory bowel disease (IBD) and to date, no effective treatment has been developed and the exact etiology of this disease remains unknown. Nevertheless, a growing number of proteomic and lipidomic studies have identified certain proteins and lipids which can be used successfully in patients to improve diagnoses and monitoring of treatment.

EXPERIMENTAL DESIGN

We have focused on the applications of proteins and lipids for IBD diagnostics, including differentiation of Crohn's disease (CD) and ulcerative colitis (UC), treatment monitoring, monitoring of clinical state, likelihood of relapse, and their potential for novel targeted treatments.

RESULTS

Analysis of protein and lipid profiles can: improve the availability and use of diagnostic markers; improve understanding of the pathomechanisms of IBD, for example, several studies have implicated platelet dysfunction (PF4), autoimmune responses (granzyme B, perforin), and abnormal metabolism (arachidonic acid pathways); aid in monitoring patient health; and improve therapeutics (experimental phosphatidylcholine therapy has been shown to result in an improvement in intestinal condition).

CONCLUSIONS

Despite the enormous progress of proteomics and lipidomics in recent years and the development of new technologies, further research is needed to select some of the most sensitive and specific markers applicable in diagnosing and treating IBD.

Mucosal and plasma metabolomes in new-onset paediatric inflammatory bowel disease: correlations with disease characteristics and plasma inflammation protein markers

BACKGROUND AND AIMS

To advance the understanding of inflammatory bowel disease (IBD) pathophysiology, we compared the mucosal and plasma metabolomes between new-onset paediatric IBD patients and symptomatic non-IBD controls, and correlated plasma inflammation markers and disease characteristics with the altered metabolites.

METHODS

Paired colonic and ileal biopsies and plasma from 67 treatment-naïve children with incident Crohn's disease (CD; n=47), ulcerative colitis (UC; n=9), and non-IBD controls (n=11) were analysed using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). Inflammatory plasma proteins (n=92) were assessed.

RESULTS

The metabolomes in inflamed mucosal biopsies differed between IBD patients and controls. In CD, mucosal levels of several lysophospholipids (lysophosphatidylcholines, lysophosphatidyletanolamines, lysophosphatidylinositols, and lysophosphatidylserines) were decreased, correlating with various plasma metabolites, including amino acid analogues and N-acetylated compounds. In both CD and UC, mucosal sphingolipids, including ceramide (d18:2/24:1, d18:1/24:2), lactosyl-N-palmitoyl-sphingosine (d18:1/16:0), behenoyl sphingomyelin (d18:1/22:0), lignoceroyl sphingomyelin (d18:1/24:0), and/or sphingomyelin (d18:1/24:1, d18:2/24:0) were increased, correlating with sphingolipids, bile acids, and/or N-acetylated metabolites in plasma. Among proteins associated with CD, interleukin-24 correlated with plasma metabolites, including lactosyl-N-palmitoyl sphingosine (d18:1/16:0) and phosphatidyletanolamine (18:1/18:1), haemoglobin, and faecal calprotectin. In UC, interleukin-24, interleukin-17A, and C-C motif chemokine 11 correlated with several plasma metabolites, including N-acetyltryptophan, tryptophan, glycerate, and threonate, and with the paediatric ulcerative colitis activity index, C-reactive protein, and faecal-calprotectin.

CONCLUSIONS

Mucosal perturbations of lysophospholipids and sphingolipids characterised the metabolome in new-onset paediatric IBD and correlated with plasma metabolites. By integrating plasma metabolomics data with inflammatory proteins and clinical data, we identified clinical and inflammatory markers associated with metabolomic signatures for IBD.

Effect of fecal microbiota transplantation on the TGF-β1/Smad signaling pathway in rats with TNBS-induced colitis

Background

Traditional treatments for inflammatory bowel disease (IBD) have adverse side effects, and patients who receive such treatments have high recurrence rates. Fecal microbiota transplantation (FMT) has become an increasingly popular therapeutic option for patients with IBD. However, the mechanism by which FMT alleviates this disease remains unclear.

Methods

In this study, a rat model of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis was established and used to explore whether the transforming growth factor-beta 1 (TGF-β1)/small mothers against decapentaplegic (Smad) signaling pathway plays a critical role in the FMT alleviation of IBD.

Results

After the FMT intervention, the disease activity index and histologic scores were significantly decreased. In addition, the TGF-β1 expression level in the FMT group was significantly decreased by approximately 0.72-fold relative to the level in the TNBS colitis group, whereas the Smad3, Smad4, and Smad7 expression levels had increased by approximately 1.21, 1.40, and 1.18 folds, respectively. Similarly, SB431542 inhibited the expression of TGF-β1 and promoted the expression of Smad3, Smad4, and Smad7. Further, the serum levels of the inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) were significantly decreased, whereas that of the interferon-gamma (IFN-γ) was not significantly changed after the FMT intervention.

Conclusions

These results suggest that FMT inhibits the TGF-β1/Smad signaling pathway to attenuate inflammation.

Fat of the Gut: Epithelial Phospholipids in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.

A Turing mechanism in order to explain the patchy nature of Crohn's disease

Crohn's disease is an inflammatory bowel disease (IBD) that is not well understood. In particular, unlike other IBDs, the inflamed parts of the intestine compromise deep layers of the tissue and are not continuous but separated and distributed through the whole gastrointestinal tract, displaying a patchy inflammatory pattern. In the present paper, we introduce a toy-model which might explain the appearance of such patterns. We consider a reaction-diffusion system involving bacteria and phagocyte and prove that, under certain conditions, this system might reproduce an activator-inhibitor dynamic leading to the occurrence of Turing-type instabilities. In other words, we prove the existence of stable stationary solutions that are spatially periodic and do not vanish in time. We also propose a set of parameters for which the system exhibits such phenomena and compare it with realistic parameters found in the literature. This is the first time, as far as we know, that a Turing pattern is investigated in inflammatory models.

Unique Regulation of Intestinal Villus Epithelial Cl-/HCO3- Exchange by Cyclooxygenase Pathway Metabolites of Arachidonic Acid in a Mouse Model of Spontaneous Ileitis

Electrolytes (NaCl) and fluid malabsorption cause diarrhea in inflammatory bowel disease (IBD). Coupled NaCl absorption, mediated by Na⁺/H⁺ and Cl^-/HCO₃^- exchanges on the intestinal villus cells brush border membrane (BBM), is inhibited in IBD. Arachidonic acid metabolites (AAMs) formed via cyclooxygenase (COX) or lipoxygenase (LOX) pathways are elevated in IBD. However, their effects on NaCl absorption are not known. We treated SAMP1/YitFc (SAMP1) mice, a model of spontaneous ileitis resembling human IBD, with Arachidonyl Trifluoro Methylketone (ATMK, AAM inhibitor), or with piroxicam or MK-886, to inhibit COX or LOX pathways, respectively. Cl^-/HCO₃^- exchange, measured as DIDS-sensitive ³⁶Cl uptake, was significantly inhibited in villus cells and BBM vesicles of SAMP1 mice compared to AKR/J controls, an effect reversed by ATMK. Piroxicam, but not MK-886, also reversed the inhibition. Kinetic studies showed that inhibition was secondary to altered K_m with no effects on V_max. Whole cell or BBM protein levels of Down-Regulated in Adenoma (SLC26A3) and putative anion transporter-1 (SLC26A6), the two key BBM Cl^-/HCO₃^- exchangers, were unaltered. Thus, inhibition of villus cell Cl^-/HCO₃^- exchange by COX pathway AAMs, such as prostaglandins, via reducing the affinity of the exchanger for Cl^-, and thereby causing NaCl malabsorption, could significantly contribute to IBD-associated diarrhea.