Sites Of Intestinal Inflammation Research Articles

Melanin Nanoparticle-Modified Probiotics for Targeted Synergistic Therapy of Ulcerative Colitis.

Ulcerative colitis (UC) is a recurrent chronic mucosal inflammation disease whose most significant pathological characteristics are intestinal inflammation and damaged mucosal barrier induced by reactive oxygen/nitrogen species, abnormal immune microenvironment, and intestinal microecological imbalance. Oral probiotics are a living therapy for intestinal diseases, but their clinical application is hindered by poor bacterial biological activity and insufficient intestinal retention. Here, we developed a targeted oral formulation, functionalized probiotic Lf@MPB, with Lactobacillus fermentum (Lf) as the core and modified melanin nanoparticles (MNPs) on its surface through a click reaction of tricarboxyphenylboronic acid for synergistic therapy of UC. In vitro experiments showed that Lf@MPB not only possessed strong free radical scavenging ability, reduced cellular mitochondrial polarization, and inhibited apoptosis but also significantly enhanced the viability of Lf probiotics in simulated gastrointestinal fluid. Fluorescence imaging in vivo revealed the high accumulation of Lf@MPB at the site of intestinal inflammation in dextran sulfate sodium-induced UC mice. Moreover, in vivo results demonstrated that Lf@MPB effectively alleviated oxidative stress and inflammatory response and restored the intestinal barrier. In addition, 16S rRNA gene sequencing verified that Lf@MPB could increase the abundance and diversity of intestinal microbial communities and optimize microbial composition to inhibit the progression of UC. This work combines effective antioxidant and anti-inflammatory strategies with the oral administration of functionalized probiotics to provide a promising alternative for UC treatment.

Extracellular vesicles package dsDNA to aggravate Crohn\u2019s disease by activating the STING pathway

Crohn’s disease (CD) is an intestinal immune-dysfunctional disease. Extracellular vesicles (EVs) are membrane-enclosed particles full of functional molecules, e.g., nuclear acids. Recently, EVs have been shown to participate in the development of CD by realizing intercellular communication among intestinal cells. However, the role of EVs carrying double-strand DNA (dsDNA) shed from sites of intestinal inflammation in CD has not been investigated. Here we isolated EVs from the plasma or colon lavage of murine colitis and CD patients. The level of exosomal dsDNA, including mtDNA and nDNA, significantly increased in murine colitis and active human CD, and was positively correlated with the disease activity. Moreover, the activation of the STING pathway was verified in CD. EVs from the plasma of active human CD triggered STING activation in macrophages in vitro. EVs from LPS-damaged colon epithelial cells were also shown to raise inflammation in macrophages via activating the STING pathway, but the effect disappeared after the removal of exosomal dsDNA. These findings were further confirmed in STING-deficient mice and macrophages. STING deficiency significantly ameliorated colitis. Besides, potential therapeutic effects of GW4869, an inhibitor of EVs release were assessed. The application of GW4869 successfully ameliorated murine colitis by inhibiting STING activation. In conclusion, exosomal dsDNA was found to promote intestinal inflammation via activating the STING pathway in macrophages and act as a potential mechanistic biomarker and therapeutic target of CD.

Colon-targeted delivery of tacrolimus using pH-responsive polymeric nanoparticles for murine colitis therapy

The present study aimed at constructing an oral nanoparticle delivery system loaded with tacrolimus (FK506) for effective treatment of inflammatory bowel disease. A FK506/HP-β-CD inclusion compound was prepared by grinding to increase drug solubility. To address the side- effects in non-target organs and systemic toxicity of FK506, pH-responsive Eudragit S100 (ES100) and hyaluronic acid (HA) with high affinity to CD44 receptor were adsorbed onto the surface of chitosan (CS) nanoparticles loaded with FK506/HP-β-CD through electrostatic interactions to obtain FK506@ES100/HA/CS/HP-β-CD nanoparticles (FK506@EHCh NPs). Caco-2 cells and Raw 264.7 macrophages were used to confirm the lack of cytotoxicity and good uptake ability of the newly generated nanoparticles. FK506@EHCh NPs significantly suppressed secretion of TNF-α, IL-1β and IL-6 by LPS-activated Raw 264.7 macrophages. A dextran sodium sulfate (DSS)-induced inflammatory bowel disease (IBD) murine model was established to further confirm the colon targeting and in vivo efficacy of oral IR-775@EHCh NPs. Based on the collective results, we conclude that packaging FK506 into active targeting nanocarriers sensitive to pH facilitates concentration of the drug within the sites of intestinal inflammation and improves the drug levels in target tissues, thus avoiding systemic side-effects and improving efficacy. In view of the promising results obtained in this study, the potential of EHCh nanoparticles for drug delivery and targeted treatment of inflammatory bowel disease warrants further investigation.

Creeping Fat in Crohn’s Disease: Innocuous or innocuum?

In Crohn's disease, the characteristic expansion of mesenteric tissue on sites of intestinal inflammation is known as creeping fat. In a recent issue of Cell, Ha etal. report that translocation of gut bacteria to the mesenteries is associated with the formation of creeping fat.

Heparin-Coated Albumin Nanoparticles for Drug Combination in Targeting Inflamed Intestine.

Targeting areas of inflammation offers potential therapeutic and diagnostic benefits by maximizing drug and imaging marker on-target effects while minimizing systemic exposure that can be associated with adverse side effects. This strategy is particularly beneficial in the management of inflammatory bowel disease (IBD). Here an inflammation-targeting (IT) approach based on heparin-coated human serum albumin nanoparticles (HEP-HSA NPs) that utilize the increased intestinal permeability and changes in electrostatic interaction at the site of intestinal inflammation is described. Using small-molecule and biologic drugs as a model for drug combination, the HEP-HSA NPs demonstrate the capacity to load both drugs simultaneously; the dual-drug loaded HEP-HSA NPs exhibit a higher anti-inflammatory effect than both of the single-drug loaded NPs in vitro and selectively bind to inflamed intestine after enema administration in vivo in a murine model of colitis. Importantly, analyses of the physicochemical characteristics and targeting capacities of these NPs indicate that HEP coating modulates NP binding to the inflamed intestine, providing a foundation for future IT-NP formulation development.

Activation of pH-Sensing Receptor OGR1 (GPR68) Induces ER Stress Via the IRE1\u03b1/JNK Pathway in an Intestinal Epithelial Cell Model

Proton-sensing ovarian cancer G-protein coupled receptor (OGR1) plays an important role in pH homeostasis. Acidosis occurs at sites of intestinal inflammation and can induce endoplasmic reticulum (ER) stress and the unfolded protein response (UPR), an evolutionary mechanism that enables cells to cope with stressful conditions. ER stress activates autophagy, and both play important roles in gut homeostasis and contribute to the pathogenesis of inflammatory bowel disease (IBD). Using a human intestinal epithelial cell model, we investigated whether our previously observed protective effects of OGR1 deficiency in experimental colitis are associated with a differential regulation of ER stress, the UPR and autophagy. Caco-2 cells stably overexpressing OGR1 were subjected to an acidic pH shift. pH-dependent OGR1-mediated signalling led to a significant upregulation in the ER stress markers, binding immunoglobulin protein (BiP) and phospho-inositol required 1α (IRE1α), which was reversed by a novel OGR1 inhibitor and a c-Jun N-terminal kinase (JNK) inhibitor. Proton-activated OGR1-mediated signalling failed to induce apoptosis, but triggered accumulation of total microtubule-associated protein 1 A/1B-light chain 3, suggesting blockage of late stage autophagy. Our results show novel functions for OGR1 in the regulation of ER stress through the IRE1α-JNK signalling pathway, as well as blockage of autophagosomal degradation. OGR1 inhibition might represent a novel therapeutic approach in IBD.

Luminal Extracellular Vesicles (EVs) in Inflammatory Bowel Disease (IBD) Exhibit Proinflammatory Effects on Epithelial Cells and Macrophages.

Extracellular vesicles (EVs) are membrane-enclosed particles released by cells as a means of intercellular communication. They are potential novel biomarkers, as they are readily isolated from body fluids, and their composition reflects disease pathways. Whether these particles are released from sites of intestinal inflammation in inflammatory bowel disease (IBD) has not previously been determined. EVs were isolated by ultracentrifugation of colonic luminal fluid aspirates and characterized according to surface proteins, and constituent mRNA and proteins. The effects of EVs on colonic epithelial cells and macrophages in culture were assessed at the transcriptional, translational, and functional levels. Intestinal luminal aspirates contained abundant EVs, at a mean concentration of 4.3 × 10 particles/mL and with a mean diameter of 146 nm. EVs from patients with IBD with a high endoscopic score (≥1) contained significantly higher mRNA and protein levels of interleukin 6 (IL-6), IL-8, IL-10, and tumor necrosis factor α than EVs from healthy controls. EVs were absorbed by cultured colonic epithelial cells, leading to an increased translation of IL-8 protein by recipient cells when treated with EVs from patients with IBD. EVs and EV-treated epithelial cells induced migration of a significantly greater number of macrophages than epithelial cells alone. EVs shed from sites of intestinal inflammation in patients with IBD have a distinct mRNA and protein profile from those of healthy individuals. These EVs have proinflammatory effects on the colonic epithelium, in vitro. Their stability in luminal samples and their mRNA and protein content identify them as a potential fecal biomarker that reflects mucosal inflammatory pathways.

New strategies for treatment of inflammatory bowel disease.

The etiology of inflammatory bowel disease (IBD), of which ulcerative colitis (UC) and Crohn’s disease (CD) are the two most prevailing entities, is unknown. However, IBD is characterized by an imbalanced synthesis of pro-inflammatory mediators of the inflamed intestine, and for more than a decade tumor necrosis factor-(TNF) α has been a major target for monoclonal antibody therapy. However, TNF inhibitors are not useful for one third of all patients (i.e. “primary failures”), and further one third lose effect over time (“secondary failures”). Therefore, other strategies have in later years been developed including monoclonal antibodies targeting the interleukin (IL)-6 family of receptors (the p40 subunit of IL-12/IL-23) as well as monoclonal antibodies inhibiting adhesion molecules (the α4β7 heterodimers), which direct leukocytes to the intestinal mucosa. Recently, small molecules, which are inhibitors of Janus kinases (JAKs), hold promise with a tolerable safety profile and efficacy in UC, and the field of nanomedicine is emerging with siRNAs loaded into polyactide nanoparticles that may silence gene transcripts at sites of intestinal inflammation. Thus, drug development for IBD holds great promise, and patients as well as their treating physicians can be hopeful for the future.

Primary Sclerosing Cholangitis and Disease Distribution in Inflammatory Bowel Disease

The relationship between site of intestinal inflammation and primary sclerosing cholangitis (PSC) development in inflammatory bowel disease (IBD) has not been studied extensively, but may be important in understanding the pathogenesis of PSC. We aimed to determine patterns of disease distribution in IBD patients with and without PSC. We performed a 2-part study involving the following: (1) 2754 IBD patients and (2) 82 separate PSC patients attending the Irish National Liver Transplant Unit. Fifty-nine of 2708 (2.2%) IBD patients had PSC. In ulcerative colitis patients, PSC incidence increased with increasing colonic involvement (P = .001) and was relatively rare in those without total colitis. Thirteen Crohn's disease patients had PSC, none with isolated small-bowel disease had PSC (P = .03). In study 2, the majority of ulcerative colitis patients with PSC had total colitis, whereas the remainder had disease extending at least to the left colon. In addition, all 10 PSC patients with Crohn's disease had colonic involvement. An inflamed colon, but not small bowel, is important in PSC development and it is possible that bacterial translocation and subsequent portal bacteremia is important in PSC development in IBD.

The Relationship between Autoimmune Bullous Disease and Systemic Disorders

The mystery of the association of skin disease with systemic disease has been a matter of fascination to dermatologists for hundreds of years. There are a myriad of articles and case reports linking various cutaneous findings to internal disease. The implication has always been that some soluble or cellular factor is being produced that results in a cutaneous disease. Immunobullous disease associates a particular antibody with a cutaneous disease and so the responsible factor for associating an immunobullous disease with a systemic disease is production of an antibody. We will review the milestones in immunobullous disease that have refined our understanding of these associations and consider possible pathogenic mechanisms. Dermatitis herpetiformis (DH) is a papulovesicular skin disease with gluten-sensitive enteropathy (celiac disease, CD) and a unique HLA type (HLADQ2 and DQ8) associated in virtually all cases. Granular deposition of IgA is the immunopathological hallmark. Marks et al. (1966) are generally credited with describing the association of CD with DH. Marks, Fry, and others established that the skin disease with its IgA deposition as well as the intestinal disorder responded to gluten restriction and recurred with the reinstitution of a gluten-containing diet culminating in a landmark paper on gluten challenge in 1983 (Leonard et al., 1983). Katz and Strober (1978) clarified the association of HLA B8/DR3 with the entire spectrum of CD with DH. Kumar et al. (1987) established the presence of IgA endomysial antibodies in DH and CD patients. The endomysial antigen was found to be tissue transglutaminase, and now testing for IgA tissue transglutaminase antibody has become the standard for the serological diagnosis of CD. The link between the intestine and the skin in genetically predisposed individuals is twofold. First, Hall et al. (2007) have established that cytokines elaborated at the site of intestinal inflammation are likely critical to the inflammatory process in the skin. Second, Sardy et al. (2002) have shown that epidermal transglutaminase is the antigen bound to the IgA stimulated by the intestinal inflammatory process. The association between DH and thyroid disease is even more intricate. In 1983, Cunningham and Zone (Cunningham and Zone, 1985) closely evaluated 50 DH patients, and showed that these patients had a high incidence of thyroid autoantibodies as well as hyperthyroidism, hypothyroidism, and thyroid enlargement. Gaspari et al., 1990. showed that this association was not related to the underlying HLA B8/DR3 genotype but was likely related to a high prevalence of Hashimoto’s thyroiditis manifested by thyroid autoantibodies and was independently associated with DH. Whether or not the intestinal inflammation in DH patients is responsible for stimulating the thyroid autoimmune process by a cellular or humoral mechanism remains to be determined (Gaspari et al., 1990). Since the 1980s, several immunobullous disorders have been linked to inflammatory bowel disease including bullous pemphigoid, epidermolysis bullosa acquisita (EBA), and linear IgA bullous disease in case reports and case series. Of these, EBA appears to have the strongest association with inflammatory bowel disease. EBA, an immunobullous disorder is characterized by autoantibodies to type VII collagen, the major structural protein of anchoring fibrils, and clinical presentations resembling bullous pemphigoid, cicatricial pemphigoid, or epidermolysis bullosa. EBA has been described in patients with both Crohn’s disease and UC, with Crohn’s disease being the predominant association. In a study of 51 EBA patients, Chen et al. (2002) found that 25% (13 of 51) had inflammatory bowel disease: 12 had Crohn’s disease and 1 had UC. They also demonstrated full-length (290 kDa) type VII collagen in normal colonic extracts from four patients and type VII collagen immunoreactivity in the colonic basement membrane. Of 19 patients, 13 patients with Crohn’s disease and 4 of 31 patients with UC were found to have elevated levels of circulating antibodies to the immunodominant NC1 domain of type VII collagen by ELISA. Despite these findings, there is no evidence linking an autoantibody to the pathogenesis of inflammatory bowel disease. The presence of type VII collagen antibodies is thought to represent epitope spreading, resulting from exposure of type VII collagen epitopes due to damage to the overlying colonic mucosa. Immunobullous diseases have also been linked to malignancies. The quintessential disorder is paraneoplastic pemphigus (PNP), described by Anhalt et al. (1990). PNP is characterized by painful mucosal erosions and polymorphous

Involvement of NF-κB in the inhibitory actions of Platycarya strobilacea on the TNF-α-induced monocyte adhesion to colon epithelial cells and chemokine expression

Oxidative stress and the activation of nuclear factor (NF)-kappaB play crucial roles in the pathogenesis of inflammatory bowel disease (IBD). In the present study, we examined the effects of the ethanol extract of Platycarya strobilacea Sieb. stem (EPS) on TNF-alpha-induced monocyte adhesion to HT29 human colon epithelial cells, an initial step of colon inflammation. EPS contained high amount of polyphenols (0.241+/-0.017 mg of catechin equivalent/g of extract) and showed substantial DPPH radical scavenging activity. In addition, EPS significantly suppressed TNF-alpha-induced reactive oxygen species (ROS) increase. Moreover, TNF-alpha-induced monocyte adhesion to HT29 colon epithelial cells was significantly suppressed by EPS in a concentration-dependent manner. The reduced adhesion by EPS was correlated with suppressed expression of MCP-1 and IL-8, the major chemokines in IBD. EPS also prevented the TNF-alpha-induced nuclear translocation of NF-kappaB, one of the redox-sensitive transcription factors, in a concentration-dependent manner. Taken together, our results suggest that the anti-oxidant components of EPS prevent TNF-alpha-induced NF-kappaB activation, chemokine induction, and monocyte adhesion at the site of intestinal inflammation.

This Month in Gastroenterology

This Month in Gastroenterology