The Many Roads to Inflammatory Bowel Diseases

Therapeutic Potential of a Self-Assembling Peptide Hydrogel to Treat Colonic Injuries Associated with Inflammatory Bowel Disease

BACKGROUND AND AIMS

The Self-assembling Peptide Hydrogel [SAPH, PuraMatrix], a fully synthetic peptide solution designed to replace collagen, has recently been used to promote mucosal regeneration in iatrogenic ulcers following endoscopic submucosal dissection. Herein, we evaluated its utility in ulcer repair using a rat model of topical trinitrobenzene sulphonic acid [TNBS]-induced colonic injuries.

METHODS

Colonic injuries were generated in 7-week-old rats by injecting an ethanol solution [35%, 0.2 mL] containing 0.15 M TNBS into the colonic lumen. At 2 and 4 days post-injury, the rats were subjected to endoscopy, and SAPH [or vehicle] was topically applied to the ulcerative lesion. Time-of-flight secondary ion mass spectrometry [TOF-SIMS] was used to detect SAPH. Colonic expression of cytokines and wound healing-related factors were assessed using real-time polymerase chain reaction or immunohistochemistry.

RESULTS

SAPH treatment significantly reduced ulcer length [p = 0.0014] and area [p = 0.045], while decreasing colonic weight [p = 0.0375] and histological score [p = 0.0005] 7 days after injury. SAPH treatment also decreased colonic expression of interleukin [IL]-1α [p = 0.0233] and IL-6[p = 0.0343] and increased that of claudin-1 [p = 0.0486] and villin [p = 0.0183], and β-catenin staining [p = 0.0237]. TOF-SIMS revealed lesional retention of SAPH on day 7 post-injury. Furthermore, SAPH significantly promoted healing in in vivo mechanical intestinal wound models.

CONCLUSIONS

SAPH application effectively suppressed colonic injury, downregulated inflammatory cytokine expression, and upregulated wound healing-related factor expression in the rat model; thus, it may represent a promising therapeutic strategy for IBD-related colonic ulcers.

Genistein-Derived ROS-Responsive Nanoparticles Relieve Colitis by Regulating Mucosal Homeostasis

Disruption of intestinal homeostasis is an important event in the development of inflammatory bowel disease (IBD), and genistein (GEN) is a candidate medicine to prevent IBD. However, the clinical application of GEN is restricted owing to its low oral bioavailability. Herein, a reactive oxygen species (ROS)-responsive nanomaterial (defined as GEN-NP2) containing superoxidase dismutase-mimetic temporally conjugated β-cyclodextrin and 4-(hydroxymethyl)phenylboronic acid pinacol ester-modified GEN was prepared. GEN-NP2 effectively delivered GEN to the inflammation site and protected GEN from rapid metabolism and elimination in the gastrointestinal tract. In response to high ROS levels, GEN was site-specifically released and accumulated at inflammatory sites. Mechanistically, GEN-NP2 effectively increased the expression of estrogen receptor β (ERβ), simultaneously reduced the expression of proinflammatory mediators (apoptosis-associated speck-like protein containing a CARD (ASC) and Caspase1-p20), attenuated the infiltration of inflammatory cells, promoted autophagy of intestinal epithelial cells, inhibited the secretion of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), modulated the gut microbiota, and ultimately alleviated colitis. In addition, the oral administration of these nanoparticles showed excellent safety, thereby providing confidence in the further development of precise treatments for IBD.

Altered serum profile of the interleukin-22 system in inflammatory bowel disease

BACKGROUND AND AIM

Interleukin-22 (IL-22), plays a vital role in the mucosal repair of inflammatory bowel disease (IBD). Serum levels of IL-22 and IL-22 binding protein (IL-22BP), a soluble inhibitory IL-22 receptor, were measured in patients with IBD to investigate the profile of IL-22 in the systemic circulation.

METHODS

Blood samples from 92 healthy subjects, 98 patients with ulcerative colitis (UC), and 105 patients with Crohn's disease (CD) were analyzed for serum levels of IL-22, IL-22BP, human β-defensin 2 (hBD-2), and serum inflammatory parameters. Disease activity was assessed by the partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum IL-22 level was lower in UC (P < 0.001) and CD (P < 0.001) vs control and its decrease was more pronounced in CD than in UC (P = 0.019). Serum IL-22BP level was lower in UC (P < 0.001) and CD (P < 0.001) vs control and correlated with inflammatory parameters (albumin and C-reactive protein (CRP) in UC; hemoglobin, albumin, and CRP in CD). Serum IL-22/IL-22BP ratios were higher in UC (P = 0.009) vs control and correlated with inflammatory parameters (albumin and CRP). Serum hBD-2 level was higher only in CD (P = 0.015) but did not correlate with serum IL-22 levels, IL-22BP levels, IL-22/IL-22BP ratios, or inflammatory parameters.

CONCLUSIONS

Dysregulation of the IL-22 system in the blood may play a role in the pathogenesis of IBD. Further studies are needed to understand the pathogenic and clinical significance of the blood IL-22 system in IBD.

Leukocyte Apheresis Using a Fiber Filter Suppresses Colonic Injury Through Calcitonin Gene-Related Peptide Induction

BACKGROUND

The aim of this study was to address whether the therapeutic effect of leukocytapheresis (LCAP) depends on calcitonin gene- related peptide (CGRP) induction.

METHODS

An HLA-B27 transgenic rat model was treated with an LCAP column. The effects of LCAP on clinical, endoscopic, and histologic disease activity, the colony-forming ability of colony-forming unit (CFU)-granulocyte macrophages (GMs), colonic blood flow, and tissue expression of tumor necrosis factor (TNF)-α and CGRP were examined. Changes in the effects of LCAP after pretreatment with the CGRP antagonist CGRP8-37 were also observed. A dextran sulfate sodium-induced colitis rat model included treatment with CGRP, and the effect was assessed based on clinical, endoscopic, and histologic disease activity, colonic blood flow, the colony-forming ability of CFU-GMs, and tissue expression of inflammatory cytokines and CGRP receptor families.

RESULTS

LCAP improved disease activity, enhanced colonic blood flow, and induced the bone marrow colony-forming ability of CFU-GMs with an increase in CGRP mRNA levels. These effects were abolished by pretreatment with CGRP8-37. The administration of CGRP suppressed colitis, promoting colonic blood flow, inducing bone marrow-derived cells, downregulating inflammatory cytokines, and upregulating receptor activity-modifying protein-1. The mRNA and protein levels of inflammatory cytokines in lipopolysaccharide-stimulated mononuclear cells were also decreased after CGRP treatment.

CONCLUSIONS

The therapeutic effects of LCAP depend on CGRP induction. CGRP can effectively suppress colitis through the downregulation of inflammatory events and upregulation of protective events.

Evaluation of Melatonin Secretion and Metabolism Exponents in Patients with Ulcerative and Lymphocytic Colitis

Inflammatory bowel diseases, particularly ulcerative colitis (UC) and lymphocytic colitis (LC), affect many people. The role of melatonin in the pathogenesis of UC is precisely determined, whereas in LC it remains unknown. The aim of this study was to compare the expression of the melatonin-synthesizing enzymes tryptophan hydroxylase (TPH1), arylalkylamine-N-acetyltransferase (AANAT), and N-acetylserotonin methyltransferase (ASMT) in the colonic mucosa and urinary excretion of 6-sulfatoxymelatonin in patients with ulcerative and lymphocytic colitis. The study included 30 healthy subjects (group C), 30 patients with severe ulcerative colitis (group UC), and 30 patients with lymphocytic colitis (group LC). The diagnosis was based on endoscopic, histological, and laboratory examinations. Biopsy specimens were collected from right, transverse, and left parts of the colon. The levels of mRNA expression, TPH1, AANAT, and ASMT were estimated in the colonic mucosa with RT-PCR. The urine concentration of aMT6s was determined by the photometric method. The expression of TPH1, AANAT, and ASMT in colonic mucosa in UC and LC patients was significantly higher than in healthy subjects. Significant differences were found in the urinary aMT6s excretion: group C—13.4 ± 4.8 µg/24 h, group UC—7.8 ± 2.6 µg/24 h (p < 0.01), group LC—19.2 ± 6.1 µg/24 h (p < 0.01). Moreover, a negative correlation was found between fecal calprotectin and MT6s—in patients with UC − r = −0.888 and with LC − r = −0.658. These results indicate that patients with UC and those with LC may display high levels of melatonin-synthesizing enzymes in their colonic mucosa, which could possibly be related to increased melatonin synthesis as an adaptive antioxidant activity.

The role of polymorphonuclear leukocyte trafficking in the perpetuation of inflammation during inflammatory bowel disease

The inflammatory bowel diseases (IBDs; Crohn's disease, and ulcerative colitis) are chronically relapsing inflammatory disorders of the intestine and/or colon. The precise etiology of IBD remains unclear, but it is thought that a complex interplay between various factors including genetic predisposition, the host immune system, and the host response to luminal microbes play a role in disease pathogenesis. Furthermore, numerous lines of evidence have implicated the accumulation of large numbers of polymorphonuclear leukocyte (PMN) in the mucosa and epithelial crypts of the intestine as a hallmark of the active disease phase of IBD. Massive infiltration of PMNs is thought to be instrumental in the pathophysiology of IBD with the degree of PMN migration into intestinal crypts correlating with patient symptoms and mucosal injury. Specifically, migrated PMN have been implicated in the impairment of epithelial barrier function, tissue destruction through oxidative and proteolytic damage, and the perpetuation of inflammation through the release of inflammatory mediators. This review highlights the multifactorial role of PMN egress into the intestinal mucosa in the pathogenesis of IBD because it represents an important area of research with therapeutic implications for the amelioration of the symptoms associated with IBD.

Modulation by melatonin of the pathogenesis of inflammatory autoimmune diseases

Melatonin is the major secretory product of the pineal gland during the night and has multiple activities including the regulation of circadian and seasonal rhythms, and antioxidant and anti-inflammatory effects. It also possesses the ability to modulate immune responses by regulation of the T helper 1/2 balance and cytokine production. Autoimmune diseases, which result from the activation of immune cells by autoantigens released from normal tissues, affect around 5% of the population. Activation of autoantigen-specific immune cells leads to subsequent damage of target tissues by these activated cells. Melatonin therapy has been investigated in several animal models of autoimmune disease, where it has a beneficial effect in a number of models excepting rheumatoid arthritis, and has been evaluated in clinical autoimmune diseases including rheumatoid arthritis and ulcerative colitis. This review summarizes and highlights the role and the modulatory effects of melatonin in several inflammatory autoimmune diseases including multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes mellitus, and inflammatory bowel disease.

Insight into Crohn's disease pathomorphology

Crohn's disease (CD) belongs together with ulcerative colitis to the two major forms of inflammatory bowel diseases (IBD). Although its etiology remains poorly understood, several genetic and immune factors and cells (especially T cells) have been shown to be involved in the pathogenesis of IBD. Among these factors, proinflammatory T cells and their secreted cytokines seem to be the main effectors in induction and perpetuation of the intestinal inflammation. Beside the local inflammatory effect, there is a very clear defined mechanism where T cells and inflammatory complexes migrate and induce extraintestinal manifestation and complications. This article reviews current knowledge of the pathomorphology of mucosal inflammation in CD focusing especially on the immune mechanisms of T-cell homing, extraintestinal manifestations and fibrogenesis.

Therapeutic leukocytapheresis in inflammatory bowel disease: clinical efficacy and mechanisms of action

Intense infiltration of the intestinal mucosa by activated leukocytes is a hallmark of inflammatory bowel disease (IBD). Therefore, removal of circulating leukocytes may be an attractive approach for treating IBD. Leukocytapheresis with Cellsorba, a column of polyethylenephtarate fibers that captures monocytes, granulocytes and lymphocytes, has been used to treat IBD, particularly ulcerative colitis, in Japan and Europe. This article reviews the clinical efficacy and safety data and the mechanisms of action of leukocytapheresis in IBD. Although the majority of clinical studies enrolled only small numbers of patients and had open-labeled designs, leukocytapheresis showed clinical efficacy with an excellent safety profile. Leukocytapheresis depletes granulocytes, monocytes, lymphocytes and platelets, alters cell population profiles, modulates cytokine production, and induces bone marrow-derived cells. In conclusion, leukocytapheresis exerts anti-inflammatory and tissue-repairing effects on the intestinal mucosa in IBD. Further studies are needed to explain the exact mechanism of action and to determine the true efficacy of this approach.

IL-13 signaling via IL-13R alpha2 induces major downstream fibrogenic factors mediating fibrosis in chronic TNBS colitis

BACKGROUND & AIMS

Previous studies have shown that fibrosis developing in chronic experimental colitis is driven by interleukin (IL)-13 signaling via IL-13R alpha(2) and the production of transforming growth factor (TGF)-beta1. In the present study, we sought to determine the fibrogenic downstream events set in motion by such signaling.

METHODS

Experimental colitis with late-onset intestinal fibrosis was induced by weekly intrarectal administration of trinitrobenzene sulfonic acid (TNBS) to BALB/c mice. Blockade of IL-13 signaling via IL-13R alpha(2) and TGF-beta1 signaling was achieved by the administration of small interfering RNA or decoy oligonucleotides that target promoter sequences of signaling components of these receptors. Effects of blockade were determined by enzyme-linked immunosorbent assay or Western blotting detecting specific key fibrogenic factors and by measurement of collagen production.

RESULTS

Initially, we showed that abrogation of IL-13 activity via blockade of IL-13R alpha(2) and TGF-beta1 signaling results in severe inhibition of expression of colonic insulin-like growth factor (IGF)-I and early growth response gene (Egr)-1, factors known to initiate and sustain fibrosis. We then showed that Egr-1 was necessary early in the fibrotic process for caspase-mediated apoptosis of myofibroblasts and the production of urokinase plasminogen activator, a protein that enhances TGF-beta1 activation. Finally, we showed that IGF-I (together with TGF-beta1) acts later in the process to stimulate myofibroblasts to deposit collagen in the colon.

CONCLUSIONS

These studies establish that IL-13 signaling via the IL-13R alpha(2) is a key initiation point for a complex fibrotic program in the colon consisting of TGF-beta1 activation, IGF-I and Egr-1 expression, myofibroblast apoptosis, and myofibroblast production of collagen.

Lack of evidence for association of primary sclerosing cholangitis and primary biliary cirrhosis with risk alleles for Crohn's disease in Polish patients

BACKGROUND

Numerous papers have addressed the association of mutations and polymorphisms of susceptibility genes with autoimmune inflammatory disorders. We investigated whether polymorphisms that confer susceptibility to Crohn's disease could be classified also as predisposing factors for the development of primary sclerosing cholangitis and primary biliary cirrhosis in Polish patients.

METHODS

The study included 60 patients with CD, 77 patients with PSC, of which 61 exhibited IBD (40 UC, 8 CD, and 13 indeterminate colitis), and 144 patients with PBC. All the patients were screened against Crohn's disease associating genetic polymorphisms. The polymorphisms were chosen according to previously confirmed evidence for association with Crohn's disease, including Pro268Ser, Arg702Trp, Gly908Arg and 1007fs in NOD2/CARD15, Leu503Phe/-207G>C in SLC22A4/OCTN1/SLC22A5/OCTN2, Arg30Gln in DLG5, Thr300Ala in ATG16L1, and Arg381Gln, His3Gln and exon-3'UTR in IL23R. Genotyping was carried out using TaqMan SNP genotyping assays.

RESULTS

We confirmed a strong association between three NOD2/CARD15 gene variants (Pro268Ser, OR = 2.52, 95% CI = 1.34-4.75); (Arg702Trp, OR = 6.65, 95% CI = 1.99-22.17); (1007fs, OR = 9.59, 95% CI = 3.94-23.29), and a weak association between both the protective OCTN1/OCTN2 CC haplotype (OR = 0.28, 95% CI = 0.08-0.94), and a variant of ATG16L1 gene (Thr300Ala, OR = 0.468, 95% CI = 0.24-0.90) with Crohn's disease. In contrast, none of the polymorphisms exhibited association with susceptibility to primary sclerosing cholangitis and primary biliary cirrhosis, including a group of primary sclerosing cholangitis patients with concurrent IBD.

CONCLUSION

Although the clinical data indicate non-random co-occurrence of inflammatory bowel disease and primary sclerosing cholangitis, consistently with the previously published studies, no genetic association was found between the genetic variants predisposing to Crohn's disease and hepatobiliary autoimmune disorders. However, since estimation of genetic variant disproportion is limited by sample size, these negative results may also indicate that eventually shared genetic predispositions are too little to be captured by small patient groups.

Increased expression and activation of IL-12-induced Stat4 signaling in the mucosa of ulcerative colitis patients

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic inflammatory diseases with unsolved pathogenesis. Imbalanced Th1/Th2 may play a role in the sustained inflammation of IBD. In China, CD is rare but the incidence of UC has been rising steadily in the last two decades. We investigated the expression of IL-12 (p40) and IFN-gamma, and the activational state of Stat4 signaling in mucosal tissues at the site of disease from 30 active UC patients in comparison with 30 healthy controls. RT-PCR analyses revealed increased mRNA expression of IL-12 (p40) but not IFN-gamma in UC patients. Western blot analyses discovered, for the first time, increased levels of constitutive Stat4 in the cytoplasm and phosphorylated Stat4 in the nucleus of mucosal cells from UC patients. We conclude that a heightened, perhaps persistent, activational state of IL-12/Stat4, and/or IL-23/Stat4 signaling may be present in active Chinese UC patients, and possibly involved in chronic inflammation in UC.