Detection of bacterial DNA in lymph nodes of Crohn's disease patients using high throughput sequencing

The role of the three major intestinal barriers in ulcerative colitis in the elderly

With the unprecedented pace of global population aging, there has been a parallel epidemiological shift marked by increasing incidence rates of ulcerative colitis (UC) in geriatric populations, imposing a substantial disease burden on healthcare systems globally. The etiopathogenesis of UC in the elderly remains poorly delineated, while current therapeutic strategies require further optimization to accommodate the unique pathophysiological characteristics of elderly patients. This review systematically elucidates the three barrier dysfunction - encompassing the gut microbiota ecosystem, mucosal epithelial integrity, and immunoregulatory network - that collectively drives UC pathogenesis during biological senescence. We emphasize the therapeutic potential of barrier-targeted interventions, particularly highlighting emerging modalities including fecal microbiota transplantation, intestinal organoid regeneration techniques, mesenchymal stem cell-mediated immunomodulation, and precision-engineered Chimeric Antigen Receptor T-cell therapies. Through this multidimensional analysis, we propose a paradigm-shifting approach to UC management in the elderly, advocating for the development of tailored and evidence-based therapeutic interventions that address the complex interplay between age-related biological changes and intestinal barrier homeostasis in elderly patients.

Navigating SARS-CoV-2-related immunopathology in Crohn's disease: from molecular mechanisms to therapeutic challenges

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) not only posed major health and economic burdens to international societies but also threatens patients with comorbidities and underlying autoimmune disorders, including Crohn's disease (CD) patients. As the vaccinated population is gradually relieved from the stress of the latest omicron variant of SARS-CoV-2 due to competent immune responses, the anxiety of CD patients, especially those on immunosuppressive treatment, has not subsided. Whether the use of immunosuppressants for remission of CD outweighs the potential risk of severe coronavirus disease 2019 (COVID-19) has long been discussed. Thus, for the best benefit of CD patients, our primary goal in this study was to navigate the clinical management of CD during the COVID pandemic. Herein, we summarized COVID-19 outcomes of CD patients treated with immunosuppressive agents from multiple cohort studies and also investigated possible mechanisms of how SARS-CoV-2 impacts the host immunity with special consideration of CD patients. We first looked into the SARS-CoV-2-related immunopathology, including lymphocytopenia, T-cell exhaustion, cytokine storms, and their possible molecular interactions, and then focused on mechanistic actions of gastrointestinal systems, including interruption of tryptophan absorption, development of dysbiosis, and consequent local and systemic inflammation. Given challenges in managing CD, we summarized up-to-date clinical and molecular evidence to help physicians adjust therapeutic strategies to achieve the best clinical outcomes for CD patients.

Alleviation of colitis by honeysuckle MIR2911 via direct regulation of gut microbiota

Inflammatory bowel disease (IBD) is a group of chronic relapsing diseases associated with inflammatory disorders and microbial dysbiosis of the intestine. The use of traditional Chinese medicine (TCM) to treat colitis has the advantage of fewer side effects, but the molecular mechanism is not clear. Recently, miRNAs have been recognized as novel functional small molecules in plants that have regulatory effects on biological activities. This study mainly investigated the mechanism of action of MIR2911 from Honeysuckle, the main component of TCM preparations for colitis. The results demonstrated that MIR2911 can be absorbed through the diet and secreted within host small extracellular vesicles (sEVs), acting directly on intestinal bacteria, reducing the abundance of Escherichia-Shigella, and improving colitis symptoms. This study provides a new theoretical basis for the molecular mechanism of TCM therapy and identifies a potential new drug a new drug target for the treatment of colitis.

Crohn's disease as the intestinal manifestation of pan-lymphatic dysfunction: An exploratory proposal based on basic and clinical data

Crohn's disease (CD) is caused by immune, environmental, and genetic factors. It can involve the entire gastrointestinal tract, and although its prevalence is rapidly increasing its etiology remains unclear. Emerging biological and small-molecule drugs have advanced the treatment of CD; however, a considerable proportion of patients are non-responsive to all known drugs. To achieve a breakthrough in this field, innovations that could guide the further development of effective therapies are of utmost urgency. In this review, we first propose the innovative concept of pan-lymphatic dysfunction for the general distribution of lymphatic dysfunction in various diseases, and suggest that CD is the intestinal manifestation of pan-lymphatic dysfunction based on basic and clinical preliminary data. The supporting evidence is fully summarized, including the existence of lymphatic system dysfunction, recognition of the inside-out model, disorders of immune cells, changes in cell plasticity, partial overlap of the underlying mechanisms, and common gut-derived fatty and bile acid metabolism. Another benefit of this novel concept is that it proposes adopting the zebrafish model for studying intestinal diseases, especially CD, as this model is good at presenting and mimicking lymphatic dysfunction. More importantly, the ensuing focus on improving lymphatic function may lead to novel and promising therapeutic strategies for CD.

Microbiota DNA Translocation Into Mesentery Lymph Nodes Is Associated With Early Development of Pouchitis After IPAA for Ulcerative Colitis

BACKGROUND

The role of bacterial translocation in Crohn's disease has been extensively studied. However, data regarding bacterial translocation into the mesentery in patients with ulcerative colitis were scarce.

OBJECTIVE

This study aimed to explore the relationship between bacterial translocation and postoperative outcome by comparing the microbiome profile of different anatomical sites in patients with ulcerative colitis who underwent proctocolectomy and IPAA.

DESIGN

A prospective study.

SETTING

This study was conducted at the Jinling Hospital from August 2017 to May 2018.

PATIENTS

Samples of 27 patients with ulcerative colitis who had IPAA and 15 healthy controls who underwent routine colonoscopy were collected.

MAIN OUTCOME MEASURES

The microbiome profile of different tissue sites and short- and long-term outcomes after IPAA in patients with ulcerative colitis.

RESULTS

Bacterial DNA was detected in mesenteric lymph nodes of 51.9% of patients with ulcerative colitis (14/27) and in mesenteric adipose tissue of 66.7% of patients (18/27). The microbiome in mesenteric lymph nodes and mesenteric adipose tissue resembled the mucosal microbiome to a greater extent than the fecal microbiome. Positive bacterial DNA in mesenteric lymph nodes (8/14 vs 0/13; p = 0.002) was associated with pouchitis within 12 months after IPAA, whereas Bray-Curtis distance in mesenteric lymph nodes was significantly different between patients with pouchitis and without ( p = 0.009).

LIMITATIONS

This study was limited by its small sample size and lacked situ experiment to confirm the true bacterial translation.

CONCLUSIONS

Bacterial translocation was highly prevalent in patients with ulcerative colitis. The translocated bacteria DNA in mesenteric adipose tissue and mesenteric lymph nodes was highly correlated and more likely to originate from mucosal than fecal microbiome. Also, the extent of bacterial translocation and translocation of certain bacteria might be associated with the early development of pouchitis after IPAA. This might represent an unprecedented technique to predict pouchitis using mesenteric lymph node bacterial profiles. See Video Abstract at http://links.lww.com/DCR/C119 .

LA TRANSLOCACIN DEL ADN DE LA MICROBIOTA EN LOS GANGLIOS LINFTICOS DEL MESENTERIO SE ASOCIA CON EL DESARROLLO TEMPRANO DE POUCHITIS DESPUS DE IPAA PARA LA COLITIS ULCEROSA

ANTECEDENTES:El papel de la translocación bacteriana en la enfermedad de Crohn se ha estudiado ampliamente en los últimos años. Sin embargo, los datos sobre la translocación bacteriana en el mesenterio en pacientes con colitis ulcerosa fueron escasos.OBJETIVO:El objetivo de este estudio fue explorar la relación entre la translocación bacteriana y el resultado postoperatorio comparando el perfil del microbioma de diferentes sitios anatómicos en pacientes con colitis ulcerosa que se sometieron a proctocolectomía y anastomosis ileoanal con bolsa.DISEÑO:Estudio prospectivo.AJUSTE:Este estudio se realizó en el Hospital Jinling desde agosto de 2017 hasta mayo de 2018.PACIENTES:Se recogieron muestras de 27 pacientes con colitis ulcerosa que tenían anastomosis de bolsa ileoanal y 15 controles sanos que se sometieron a una colonoscopia de rutina.PRINCIPALES MEDIDAS DE RESULTADO:El perfil del microbioma de diferentes sitios de tejido y los resultados a corto y largo plazo después de la anastomosis ileoanal con bolsa en pacientes con colitis ulcerosa.RESULTADOS:Se detectó ADN bacteriano en los ganglios linfáticos mesentéricos del 51,9 % (14/27) de los pacientes con colitis ulcerosa y en el tejido adiposo mesentérico del 66,7 % (18/27) de los pacientes, respectivamente. El microbioma en los ganglios linfáticos mesentéricos y el tejido adiposo mesentérico se parecía más al microbioma de la mucosa que al microbioma fecal. El ADN bacteriano translocado en los ganglios linfáticos mesentéricos y el tejido adiposo mesentérico estaban altamente correlacionados. El ADN bacteriano positivo en los ganglios linfáticos mesentéricos (8/14 frente a 0/13, p = 0,002) se asoció con reservoritis dentro de los 12 meses posteriores a la anastomosis ileoanal con reservorio, mientras que la distancia de Bray-Curtis en los ganglios linfáticos mesentéricos fue significativamente diferente entre reservoritis y no reservorios. -pacientes con reservorio (p = 0,009). Ruminococcus, Bacteroides y Clostridiales se encontraron exclusivamente en los ganglios linfáticos mesentéricos de pacientes con reservoritis.LIMITACIÓN:Este estudio estuvo limitado por el pequeño tamaño de la muestra y la falta de un experimento in situ para confirmar la verdadera traducción bacteriana.CONCLUSIÓN:La translocación bacteriana fue altamente prevalente en pacientes con colitis ulcerosa. El ADN bacteriano translocado en el tejido adiposo mesentérico y los ganglios linfáticos mesentéricos estaba altamente correlacionado y era más probable que se originara en el microbioma de la mucosa que en el fecal. Además, la extensión de la translocación bacteriana y la translocación de ciertas bacterias podría estar asociada con el desarrollo temprano de reservoritis después de la anastomosis del reservorio ileoanal. Esto podría representar una técnica sin precedentes para predecir la reservoritis utilizando perfiles bacterianos de los ganglios linfáticos mesentéricos. Consulte Video Resumen en. http://links.lww.com/DCR/C119(Traducción-Dr. Felipe Bellolio ).

More than Mycobacterium tuberculosis: site-of-disease microbial communities, and their functional and clinical profiles in tuberculous lymphadenitis

BACKGROUND

Lymphadenitis is the most common extrapulmonary tuberculosis (EPTB) manifestation. The microbiome is important to human health but uninvestigated in EPTB. We profiled the site-of-disease lymph node microbiome in tuberculosis lymphadenitis (TBL).

METHODS

Fine-needle aspiration biopsies were collected from 158 pretreatment presumptive TBL patients in Cape Town, South Africa. 16S Illumina MiSeq rRNA gene sequencing was done.

RESULTS

We analysed 89 definite TBLs (dTBLs) and 61 non-TBLs (nTBLs), which had similar α- but different β-diversities (p=0.001). Clustering identified five lymphotypes prior to TB status stratification: Mycobacterium-dominant, Prevotella-dominant and Streptococcus-dominant lymphotypes were more frequent in dTBLs whereas a Corynebacterium-dominant lymphotype and a fifth lymphotype (no dominant taxon) were more frequent in nTBLs. When restricted to dTBLs, clustering identified a Mycobacterium-dominant lymphotype with low α-diversity and non-Mycobacterium-dominated lymphotypes (termed Prevotella-Corynebacterium, Prevotella-Streptococcus). The Mycobacterium dTBL lymphotype was associated with HIV-positivity and features characteristic of severe lymphadenitis (eg, larger nodes). dTBL microbial communities were enriched with potentially proinflammatory microbial short-chain fatty acid metabolic pathways (propanoate, butanoate) vs nTBLs. 11% (7/61) of nTBLs had Mycobacterium reads BLAST-confirmed as Mycobacterium tuberculosis complex.

CONCLUSIONS

TBL at the site-of-disease is not microbially homogeneous. Distinct microbial community clusters exist that, in our setting, are associated with different clinical characteristics, and immunomodulatory potentials. Non-Mycobacterium-dominated dTBL lymphotypes, which contain taxa potentially targeted by TB treatment, were associated with milder, potentially earlier stage disease. These investigations lay foundations for studying the microbiome's role in lymphatic TB. The long-term clinical significance of these lymphotypes requires prospective validation.

Diagnostic significance of mesenteric lymph node involvement in proximal small bowel Crohn's disease

BACKGROUND

The diagnosis of proximal small bowel involvement in Crohn's disease (CD) can be challenging at magnetic resonance enterography (MRE). The inflammatory process in CD can be associated with peri-intestinal inflammatory reactions, including the presence of inflamed mesenteric lymph nodes.

OBJECTIVES

To evaluate the significance of inflamed mesenteric lymph nodes adjacent to the jejunum at MRE in CD and the association with proximal bowel disease as detected by video capsule endoscopy (VCE).

DESIGN

This retrospective study was performed in two tertiary medical centres, and included 64 patients with CD who underwent MRE as well as VCE within 1 year.

METHODS

Data were collected for examinations performed between August 2013 and February 2021. MRE images were independently reviewed by radiologists who were blinded to the clinical data. Association between the presence of mesenteric lymph nodes adjacent to jejunum at MRE and disease activity according to VCE Lewis scores of proximal small bowel was examined.

RESULTS

VCE detected proximal disease in 24/64 patients (37.5%). Presence of regional lymph nodes in the jejunal mesentery was significantly associated with jejunal disease as seen on VCE (p < 0.001). Of the 20 patients who had proximal mesenteric lymph nodes at MRE, 15 (75%) had jejunal disease at VCE (sensitivity, 62.5%; specificity, 87.5%; and negative and positive predictive values, 79.5 and 75%, respectively). The number of regional lymph nodes was positively correlated with jejunal disease (mean: 2.63 ± 2.90 versus 0.78 ± 2.60, p = 0.01). Other MRE features of lymph nodes were not significantly predictive of jejunal CD.

CONCLUSION

In patients with CD, inflamed regional lymph nodes in the jejunal mesentery at MRE can be valuable to suggest proximal small bowel disease, even when bowel wall features at imaging do not suggest disease involvement.

PLAIN LANGUAGE SUMMARY

The diagnosis of proximal small bowel involvement in Crohn's disease (CD) can be challenging at magnetic resonance enterography (MRE). We analysed MRE examinations in patients with CD for the presence of lymph nodes adjacent to the proximal small bowel. We included 64 patients with CD who had MRE examinations and video capsule endoscopy (VCE) examinations within 1 year. Of 64 patients, 24 had proximal small bowel disease according to VCE. We found that of 20 patients who had regional mesenteric lymph nodes in the jejunal mesentery at MRE, 15 had proximal bowel disease involvement. We also found that patients with jejunal disease had a larger number of regional lymph nodes compared to patients without jejunal disease. All but one patient had normal appearing bowel at MRE. But, using regional mesenteric lymphadenopathy at MRE as an indicator for disease, 15/24 (62.5%) patients with proximal small bowel disease were detected. We therefore conclude that regional mesenteric lymph nodes assessment at MRE can aid diagnose proximal bowel disease, even when the proximal bowel looks normal at imaging. Presence of proximal mesenteric lymph nodes at MRE in patients with CD possibly warrant further investigation of the proximal small bowel by endoscopic measures.

The systemic anti-microbiota IgG repertoire can identify gut bacteria that translocate across gut barrier surfaces

Unique gut microbiota compositions have been associated with inflammatory diseases, but identifying gut bacterial functions linked to immune activation in humans remains challenging. Translocation of pathogens from mucosal surfaces into peripheral tissues can elicit immune activation, although whether and which gut commensal bacteria translocate in inflammatory diseases is difficult to assess. We report that a subset of commensal gut microbiota constituents that translocate across the gut barrier in mice and humans are associated with heightened systemic immunoglobulin G (IgG) responses. We present a modified high-throughput, culture-independent approach to quantify systemic IgG against gut commensal bacteria in human serum samples without the need for paired stool samples. Using this approach, we highlight several commensal bacterial species that elicit elevated IgG responses in patients with inflammatory bowel disease (IBD) including taxa within the clades Collinsella, Bifidobacterium, Lachnospiraceae, and Ruminococcaceae. These and other taxa identified as translocating bacteria or targets of systemic immunity in IBD concomitantly exhibited heightened transcriptional activity and growth rates in IBD patient gut microbiomes. Our approach represents a complementary tool to illuminate interactions between the host and its gut microbiota and may provide an additional method to identify microbes linked to inflammatory disease.

The Role of the Lymphatic System in the Pathogenesis and Treatment of Inflammatory Bowel Disease

Although the number of therapeutic options for the treatment of inflammatory bowel disease (IBD) has increased in recent years, patients suffer from decreased quality of life due to non-response or loss of response to the currently available treatments. An increased understanding of the disease’s etiology could provide novel insights for treatment strategies in IBD. Lymphatic system components are generally linked to immune responses and presumably related to inflammatory diseases pathophysiology. This review aims to summarize findings on immune-mediated mechanisms in lymphoid tissues linked with IBD pathogenesis and (potential) novel treatments. Enhanced innate and adaptive immune responses were observed in mesenteric lymph nodes (MLNs) and other lymphoid structures, such as Peyer’s patches, in patients with IBD and in animal models. Furthermore, the phenomenon of lymphatic obstruction in the form of granulomas in MLNs and lymphatic vessels correlates with disease activity. There is also evidence that abnormalities in the lymphatic stromal components and lymph node microbiome are common in IBD and could be exploited therapeutically. Finally, novel agents targeting lymphocyte trafficking have been added to the treatment armamentarium in the field of IBD. Overall, gut-associated lymphoid tissue plays a key role in IBD immunopathogenesis, which could offer novel therapeutic targets.

Prebiotic effects of goji berry in protection against inflammatory bowel disease

The prevalence of inflammatory bowel disease (IBD) is increasing, which is concerning because IBD is a known risk factor for the development of colorectal cancer. Emerging evidence highlights environmental factors, particularly dietary factors and gut microbiota dysbiosis, as pivotal inducers of IBD onset. Goji berry, an ancient tonic food and a nutraceutical supplement, contains a range of phytochemicals such as polysaccharides, carotenoids, and polyphenols. Among these phytochemicals, L. barbarum polysaccharides (LBPs) are the most important functional constituents, which have protective effects against oxidative stress, inflammation, and neurodegeneration. Recently, the beneficial effects of goji berry and associated LBPs consumption were linked to prebiotic effects, which can prevent dysbiosis associated with IBD. This review assessed pertinent literature on the protective effects of goji berry against IBD focusing on the gut microbiota and their metabolites in mediating the observed beneficial effects.

A narrative review of the role of gastrointestinal dysbiosis in the pathogenesis of polycystic ovary syndrome

Diet-induced gastrointestinal dysbiosis has been hypothesized to play a significant role in stimulating an increase in gastrointestinal permeability and activating systemic inflammation in women with polycystic ovary syndrome (PCOS). We reviewed the current proof-of-concept studies on the proposed mechanism of dysbiosis in the pathogenesis of PCOS. A literature search was performed to identify articles on changes in the intestinal microbiome (dysbiosis) and increased intestinal mucosal permeability involving lipopolysaccharide (LPS), LPS-binding protein (LPS-BP), and zonulin. We also searched for systematic reviews and meta-analyses that synthesized the results of studies on the therapeutic effects of prebiotics, probiotics, or synbiotics in women with PCOS. Our search was confined to human studies between 2012 and 2021 using the PubMed, Scopus, and Cochrane databases. Thirty-one studies met the inclusion criteria (14 microbiota, 1 LPS, 1 LPS-BP, 1 LPS and LPS-BP, 5 zonulin, 9 systematic reviews). Our analysis revealed that most studies reported reduced alpha diversity and dysbiosis in women with PCOS. Preliminary studies suggest that LPS, LPS-BP, and zonulin may be involved in the pathophysiology of increased intestinal permeability. Treatment of PCOS with prebiotics, probiotics, and synbiotics appears to have a range of beneficial effects on metabolic and biochemical profiles. This review highlights the need for continued research into the pathophysiological mechanisms of dysbiosis and the clinical efficacy of prebiotics, probiotics, and synbiotics in women with PCOS.

Dysbiotic microbiota interactions in Crohn's disease

Crohn's disease (CD) is a major form of inflammatory bowel disease characterized by transmural inflammation along the alimentary tract. Changes in the microbial composition and reduction in species diversity are recognized as pivotal hallmarks in disease dynamics, challenging the gut barrier function and shaping a pathological immune response in genetically influenced subjects. The purpose of this review is to delve into the modification of the gut microbiota cluster network during CD progression and to discuss how this shift compromises the gut barrier integrity, granting the translocation of microbes and their products. We then complete the scope of the review by retracing gut microbiota dysbiosis interactions with the main pathophysiologic factors of CD, starting from the host's genetic background to the immune inflammatory and fibrotic processes, providing a standpoint on the lifestyle/exogenous factors and the potential benefits of targeting a specific gut microbiota.

Bacterial Characteristics of Intestinal Tissues From Patients With Crohn's Disease

Background and Aims

It is believed that intestinal bacteria play an indispensable role in promoting intestinal inflammation. However, the characteristics of these tissue-associated bacteria remain elusive. The aim of this study is to explore the bacterial loads, compositions, and structures in the noninflamed mucosa, inflamed mucosa, and creeping fat taken from patients with Crohn’s disease (CD).

Methods

Noninflamed mucosa, inflamed mucosa, and creeping fat samples were obtained from 10 surgical patients suffering from CD. Total bacterial DNA was extracted in a sterile environment using aseptic techniques. The V3–V4 regions of bacterial 16S rDNA were amplified and analysed using standard microbiological methods. qPCR was used to confirm the change in abundance of specific species in additional 30 independent samples.

Results

Inflamed mucosa exhibited the highest bacterial load (3.8 and 12 times more than that of non-inflamed mucosa and creeping fat) and species diversity. The relative abundance of Proteobacteria was dominant in most samples and was negatively associated with Firmicutes. Moreover, the relative abundances of Methylobacterium and Leifsonia in creeping fat significantly increased more than twice as much as other tissue types. The bacterial community structure analysis showed that the bacterial samples from the same individual clustered more closely.

Conclusion

This study reveals the significant differences in bacterial load, species diversity, and composition among different intestinal tissue types of CD patients and confirms that the bacterial samples from the same individual are highly correlated. Our findings will shed light on fully revealing the characteristics of tissue-associated bacteria and their roles in CD pathogenesis.

Bacterial Translocation as Inflammatory Driver in Crohn's Disease

Crohn’s disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract responsible for intestinal lesions. The multifactorial etiology attributed to CD includes a combination of environmental and host susceptibility factors, which result in an impaired host–microbe gut interaction. Bacterial overgrowth and dysbiosis, increased intestinal barrier permeability, and altered inflammatory responses in patients with CD have been described in the past. Those events explain the pathogenesis of luminal translocation of bacteria or its products into the blood, a frequent event in CD, which, in turn, favors a sustained inflammatory response in these patients. In this review, we navigate through the interaction between bacterial antigen translocation, permeability of the intestinal barrier, immunologic response of the host, and genetic predisposition as a combined effect on the inflammatory response observed in CD. Several lines of evidence support that translocation of bacterial products leads to uncontrolled inflammation in CD patients, and as a matter of fact, the presence of gut bacterial genomic fragments at a systemic level constitutes a marker for increased risk of relapse among CD patients. Also, the significant percentage of CD patients who lose response to biologic therapies may be influenced by the translocation of bacterial products, which are well-known drivers of proinflammatory cytokine production by host immune cells. Further mechanistic studies evaluating cellular and humoral immune responses, gut microbiota alterations, and genetic predisposition will help clinicians to better control and personalize the management of CD patients in the future.

Randomized Trial of Ciprofloxacin Doxycycline and Hydroxychloroquine Versus Budesonide in Active Crohn's Disease

BACKGROUND

Increased mucosa-associated E. coli are present in Crohn's disease, but their role in pathogenesis is uncertain.

AIMS

To assess efficacy and safety of an antibiotic/hydroxychloroquine combination effective against E. coli inside macrophages.

METHODS

Adults with moderately active disease (CDAI > 220-450 plus C reactive protein ≥ 5 mg/l and/or fecal calprotectin > 250 μg/g) were randomized to receive (open-label) oral budesonide (Entocort CR 9 mg/day 8 weeks, 6 mg/day 2 weeks, 3 mg/day 2 weeks) or oral ciprofloxacin 500 mg bd, doxycycline 100 mg bd, hydroxychloroquine 200 mg tds for 4 weeks, followed by doxycycline 100 mg bd and hydroxychloroquine 200 mg tds for 20 weeks. Primary endpoints were remission (CDAI ≤ 150) at 10 weeks, remission maintained to 24 weeks, and remission maintained to 52 weeks. Patients not responding (CDAI fall by > 70) by 10 weeks were invited to crossover onto the alternative therapy.

RESULTS

Fifty-nine patients were recruited across 8 sites. Including crossover, 39 patients received antibiotics/hydroxychloroquine and 39 received budesonide. At 10 weeks, 24 weeks, and 52 weeks on initial therapy, only 2/27, 2/27, and 1/27 were in remission on antibiotics/hydroxychloroquine compared with 8/32, 1/32, and 1/32 on budesonide (P = 0.092 at 10 weeks). Withdrawals by 10 weeks due to adverse events were seen in 15 receiving antibiotics/hydroxychloroquine and 6 budesonide. Results including crossover were more promising with 9/24 patients receiving antibiotics/hydroxychloroquine per protocol in remission by 24 weeks. No correlation was seen between response to antibiotics/hydroxychloroquine and ASCA/OmpC antibody status or disease location.

CONCLUSION

Overall results with this antibiotic/hydroxychloroquine combination were unimpressive, but long-term remission is seen in some patients and justifies further study.

Implications of lymphatic alterations in the pathogenesis and treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by intense immune dysregulation, gut microbiota imbalance, and intestinal epithelium destruction. Among the factors that contribute to the pathogenesis of IBD, lymphatics have received less attention, hence less studied, characterized, and explored. However, in recent years, the role of the lymphatic system in gastrointestinal pathophysiology continues to be highlighted. This paper examines the implications of lymphatic changes in IBD pathogenesis related to immune cells, gut microbiota, intestinal and mesenteric epithelial barrier integrity, and progression to colorectal cancer (CRC). Therapeutic targets of lymphatics in IBD studies are also presented. Available studies indicate that lymph nodes and other secondary lymphatic tissues, provide highly specialized microenvironments for mounting effective immune responses and that lymphatic integrity plays a significant role in small intestine homeostasis, where the lymphatic vasculature effectively controls tissue edema, leukocyte exit, bacterial antigen, and inflammatory chemokine clearance. In IBD, there are functional and morphological alterations in intestinal and mesenteric lymphatic vessels (more profoundly in Crohn's disease [CD] compared to ulcerative colitis [UC]), including lymphangiogenesis, lymphangiectasia, lymphadenopathy, and lymphatic vasculature blockade, affecting not only immunity but gut microbiota and epithelial barrier integrity. While increased lymphangiogenesis is primarily associated with a good prognosis of IBD, increased lymphangiectasia, lymphadenopathy, and lymphatic vessel occlusion correlate with poor prognosis. IBD therapies that target the lymphatic system seek to increase lymphangiogenesis via induction of lymphangiogenic factors and inhibition of its antagonists. The resultant increased lymphatic flow coupled with other anti-inflammatory activities restores gut homeostasis.

Post-operative pain after laparoscopic right hemicolectomy for Crohn's disease: a case control study

AIM

Surgery for Crohn's disease (CD) is characterized by an enhanced inflammatory response. While inflammation can induce hyperalgesia, post-operative pain following surgery for CD has not been characterized. This retrospective study compared a consecutive series of patients undergoing laparoscopic right hemicolectomy for CD and neoplasia performed by a single surgeon.

METHOD

Elective resections performed between Jan-2016 and Aug-2017 managed in an enhanced recovery pathway were eligible for inclusion. Patients were excluded if open surgery was performed, an ileostomy was fashioned, no patient-controlled analgesia (PCA) was used or data were incomplete. Results : 38 cases were included, 20 for neoplasia and 18 for ileocolonic CD. There was no difference in patient gender (P=0.520). CD patients were younger (39.8±2.8 Vs 77.2±2.1 years, P<0.001) but had an equivalent length of resection (312.9±43.5 Vs 283.3±71.7 mm, P=0.915). CD patients had higher pain scores on post-operative day 1 (6.8±0.8 Vs 2.6±1.0, P<0.001), day 2 (5.0±0.5 Vs 1.6±0.9, P<0.001) and day 3 (4.1±0.6 Vs 1.3±0.7, P=0.008). CD patients used their PCA for longer (85.7±16.3 Vs 47.7±4.2 hours, P=0.017) and used a greater total amount of morphine (148.6±33.8 Vs 37.0±7.8 mg, P<0.001). Post-operative CRP was higher in patients with CD on day 1 (P=0.011), day 2 (P=0.001), day 3 (P=0.001) and day 4 (P=0.007), but no leak or intra-abdominal abscess occurred in either group.

RESULTS

38 cases were included, 20 for neoplasia and 18 for ileocolonic CD. There was no difference in patient gender (P=0.520). CD patients were younger (39.8±2.8 Vs 77.2±2.1 years, P<0.001) but had an equivalent length of resection (312.9±43.5 Vs 283.3±71.7 mm, P=0.915). CD patients had higher pain scores on post-operative day 1 (6.8±0.8 Vs 2.6±1.0, P<0.001), day 2 (5.0±0.5 Vs 1.6±0.9, P<0.001) and day 3 (4.1±0.6 Vs 1.3±0.7, P=0.008). CD patients used their PCA for longer (85.7±16.3 Vs 47.7±4.2 hours, P=0.017) and used a greater total amount of morphine (148.6±33.8 Vs 37.0±7.8 mg, P<0.001). Post-operative CRP was higher in patients with CD on day 1 (P=0.011), day 2 (P=0.001), day 3 (P=0.001) and day 4 (P=0.007), but no leak or intra-abdominal abscess occurred in either group.

CONCLUSIONS

CD patients experience increased post-operative pain, require more post-operative analgesia and have an enhanced post-operative inflammatory response. Further studies to elucidate the mechanism of this hyperalgesia and strategies to obviate it are required.

Lipopolysaccharides modulate intestinal epithelial permeability and inflammation in a species-specific manner

Patients presenting with Inflammatory bowel disease have been shown to exhibit an altered microbiome in both Crohn's disease and Ulcerative colitis. This shift in the microbial content led us to question whether several of these microbes are important in inflammatory processes present in these diseases and more specifically whether lipopolysaccharides from the gram-negative cell wall differentially stimulates resident cells. We, therefore, investigated the possible contribution of five major species of gram-negative bacteria found to be altered in presence during disease progression and evaluate their pathogenicity through LPS. We demonstrated that LPS from these different species had individual capacities to induce NF-κB and pro-inflammatory IL-8 production from HEK-TLR4 cells in a TLR4 dependent manner. Additional work using human intestinal colonic epithelial cell monolayers (Caco-2) demonstrated that the cells responded to the serotype specific LPS in a distinct manner, inducing many inflammatory mediators such as TNF-α and IL-10 in significantly altered proportions. Furthermore, the permeability of Caco-2 monolayers, as a test for their ability to alter intestinal permeability, was also differentially altered by the serotype specific LPS modulating trans-epithelial electrical resistance, small molecule movement, and tight junction integrity. Our results suggest that specific species of bacteria may be potentiating the pathogenesis of IBD and chronic inflammatory diseases through their serotype specific LPS responses.

The role of major virulence factors and pathogenicity of adherent-invasive Escherichia coli in patients with Crohn's disease

Inflammatory bowel disease (IBD) is a term that describes Crohn's disease (CD) and ulcerative colitis (UC), and these two conditions are characterised by chronic inflammation of the gastrointestinal tract. Dysbiosis of intestinal microbiota has been consistently linked to patients with IBD. In the last two decades, the progressive implication of adherent-invasive Escherichia coli (AIEC) pathogenesis in patients with CD has been increasing. Here we discuss recent findings that indicate the role and mechanisms of AIEC in IBD. We also highlight AIEC virulence factor genes and mechanisms that suggest an important role in the severity of inflammation in CD patients. Finally, we emphasise data on the prevalence of AIEC in CD patients.

Sequential Changes in the Mesenteric Lymph Node Microbiome and Immune Response during Cirrhosis Induction in Rats

Whether the interaction between the gut microbiota and the immune response influences the evolution of cirrhosis is poorly understood. We aimed to investigate modifications of the microbiome and the immune response during the progression of cirrhosis. Rats were treated with carbon tetrachloride (CCl4) to induce cirrhosis. We then assessed microbiome load and composition in stool, ileocecal contents (ICCs), mesenteric lymph nodes (MLNs), blood, and ascitic fluids (AFs) at 6, 8, and 10 weeks or ascites production and measured cytokine production in MLNs and blood. The microbiome of MLN, blood, and AF showed a distinct composition compared to that of stool and ICCs. Betaproteobacteria (Sutterella) were found associated with the appearance of a decompensated state of cirrhosis. Microbial load increased and showed a positive correlation with the relative abundance of pathobionts in the MLN of decompensated rats. Among several genera, Escherichia and "Candidatus Arthromitus" positively correlated with elevated levels of systemic proinflammatory cytokines. "Candidatus Arthromitus," a segmented filamentous bacteria, was detected in ICC, MLN, and AF samples, suggesting a possible translocation from the gut to the AF through the lymphatic system, whereas Escherichia was detected in ICC, MLN, AF, and blood, suggesting a possible translocation from the gut to the AF through the bloodstream. In the present study, we demonstrate that microbiome changes in distinct intestinal sites are associated with microbial shifts in the MLNs as well as an increase in cytokine production, providing further evidence of the role the gut-liver-immunity axis plays in the progression of cirrhosis. IMPORTANCE Cirrhosis severity in patients was previously shown to be associated with progressive changes in the fecal microbiome in a longitudinal setting. Recent evidence shows that bacterial translocation from the gut to the extraintestinal sites could play a major role in poor disease outcome and patient survival. However, the underlying mechanisms involving the microbiota in the disease progression are not well understood. Here, using an animal model of cirrhosis in a longitudinal and multibody sites setting, we showed the presence of a distinct composition of the microbiome in mesenteric lymph nodes, blood, and ascitic fluid compared to that in feces and ileocecal content, suggesting compartmentalization of the gut microbiome. We also demonstrate that microbiome changes in intestinal sites are associated with shifts in specific microbial groups in the mesenteric lymph nodes as well as an increase in systemic cytokine production, linking inflammation to decompensated cirrhosis in the gut-liver-immunity axis.

The Human Mesenteric Lymph Node Microbiome Differentiates Between Crohn's Disease and Ulcerative Colitis

BACKGROUND AND AIMS

Mesenteric lymph nodes are sites in which translocated bacteria incite and progress immunological responses. For this reason, understanding the microbiome of mesenteric lymph nodes in inflammatory bowel disease is important. The bacterial profile of Crohn's disease mesenteric lymph nodes has been analysed using culture-independent methods in only one previous study. This study aimed to investigate the mesenteric lymph node microbiota from both Crohn's disease and ulcerative colitis patients.

METHODS

Mesenteric lymph nodes were collected from Crohn's disease and ulcerative colitis patients undergoing resection. Total DNA was extracted from mesenteric lymph nodes and assessed for the presence of bacterial DNA [16S]. All work was completed in a sterile environment using aseptic techniques. Samples positive for 16S DNA underwent next-generation sequencing, and the identity of bacterial phyla and species were determined.

RESULTS

Crohn's disease mesenteric lymph nodes had a distinctly different microbial profile to that observed in ulcerative colitis. The relative abundance of Firmicutes was greater in nodes from ulcerative colitis patients, whereas Proteobacteria were more abundant in Crohn's disease. Although species diversity was reduced in the mesenteric lymph nodes of patients with Crohn's disease, these lymph nodes contained greater numbers of less dominant phyla, mainly Fusobacteria.

CONCLUSION

This study confirms that there are distinct differences between the Crohn's disease and ulcerative colitis mesenteric lymph node microbiomes. Such microbial differences could aid in the diagnosis of Crohn's disease or ulcerative colitis, particularly in cases of indeterminate colitis at time of resection, or help explain their mechanisms of development and progression.

The microbiome of Crohn's disease aphthous ulcers

Background

Reduced intestinal microbial diversity and bacterial imbalance (dysbiosis) are seen in studies of Crohn's disease. As it is difficult to obtain biopsy samples before disease presentation, the earliest mucosal lesions in Crohn's disease, aphthous ulcers, present the best chance at assessing microbial communities at the onset of disease or a new flare. The aim of our study was to compare the microbial communities of aphthous ulcers and adjacent normal mucosa from patients with Crohn's disease with normal mucosa from controls.

Results

We did not observe bacterial imbalance or reduced alpha diversity in Crohn's disease aphthous ulcers and adjacent mucosa, relative to control biopsies. Bacteroides were common to all Crohn's disease and control samples, and there were no bacterial taxa unique to aphthous ulcers. The relative abundance of Faecalibacterium was not reduced in aphthous ulcers relative to control mucosa, and was not more likely to be detected in control samples.

Conclusions

In contrast to well-documented changes seen in late-stage Crohn's disease, microbial communities of aphthous ulcers do not display evidence of bacterial imbalance or reduced diversity. Our data suggest that dysbiosis occurs during active disease, and improves when patients are in remission.

Prevalence of Yersinia Species in the Ileum of Crohn's Disease Patients and Controls

Yersinia are common contaminants of food products, but their prevalence in the human gut is poorly documented. Yersinia have been implicated in Crohn's Disease (CD, an inflammatory bowel disease) however their role in CD is controversial. We performed highly sensitive PCR assays of specific sequences for the gyrB gene of Y. aldovae, Y. bercovieri, Y. enterocolitica, Y. intermedia, Y. mollaretii and the inv gene of Y. pseudotuberculosis. We analyzed a total of 470 ileal samples taken from 338 participants (262 CD patients and 76 controls) belonging to three independent cohorts. All patients and controls were phenotyped and genotyped for the main CD susceptibility variants: NOD2, ATG16L1, and IRGM. Yersinia were found in 7.7% of ileal samples (respectively 7.9 and 7.6% in controls and CD patients) corresponding to 10% of participants (respectively 11.8 and 9.5% in controls and CD patients). Y. enterocolitica, Y. pseudotuberculosis and Y. intermedia were the most frequently identified species. The bacteria were more frequent in resected specimens, lymph nodes and Peyer's patches. Yersinia were no more likely to be detected in CD tissues than tissues from inflammatory and non-inflammatory controls. CD patients treated with immunosuppressants were less likely to be Yersinia carriers. In conclusion, this work shows that Yersinia species are frequently found at low levels in the human ileum in health and disease. The role of Yersinia species in this ecosystem should now be explored.

Effect of Different Disinfectants on Bacterial Aerosol Diversity in Poultry Houses

To better understand the effect of different disinfectants on the types and quantities of microorganisms in a broiler chicken house, five different types of disinfectants, including ozone, available chlorine, quaternary ammonium salt, glutaraldehyde, and mixed disinfectant, were used. The broiler house microbial communities were analyzed by high-throughput sequencing combined with air sampling. The results showed that the concentrations of airborne aerobic bacteria in the empty broiler houses after application of different disinfectants were significantly reduced compared to a house untreated with disinfectant (P < 0.05 or P < 0.01), and the number of inhalable particles of airborne aerobic bacteria sharply decreased after disinfection. Of the five disinfectants, the mixed disinfectant had the best disinfection efficacy on the total microbial communities (P < 0.05). A total of 508,143 high-quality sequences were obtained by high-throughput sequencing, which identified 1995 operational taxonomic units. In total, 42 phyla and 312 genera were identified. The structures of airborne microbial communities in the broiler houses after the different disinfectants were applied differed. In the house treated with the mixed disinfectant, the microbial communities containing opportunistic pathogens, such as Escherichia-Shigella, Bacillus, and Pseudomonas, had the lowest abundance, with a significant decrease compared to the house untreated with disinfectant. The alpha diversity index showed low diversity of the microbial communities in the house treated with mixed disinfectant. In contrast to the other four disinfectants, only a small amount of bacteria was detected in the air sample in the house treated with the mixed disinfectant; specifically, only four phyla were found (Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes). The mixed disinfectant produced a positive effect on disinfection for four phyla; however, it didn’t thoroughly eliminate them. At genus level, Bacillus, Arenimonas, and Shinella could not be detected in the house treated with the mixed disinfectant, but were detected in houses treated with other disinfectants. The high-throughput sequencing results revealed that the combination of multiple disinfectants exhibited a good disinfection efficacy and that this technique could disinfect the air of broiler houses. These results will help guide the development of a reasonable program for broiler house disinfection.

Proteus spp. as Putative Gastrointestinal Pathogens

Proteus species, members of the Enterobacteriaceae family, are usually considered commensals in the gut and are most commonly recognized clinically as a cause of urinary tract infections. However, the recent identification of Proteus spp. as potential pathogens in Crohn's disease recurrence after intestinal resection serves as a stimulus to examine their potential role as gut pathogens. Proteus species possess many virulence factors potentially relevant to gastrointestinal pathogenicity, including motility; adherence; the production of urease, hemolysins, and IgA proteases; and the ability to acquire antibiotic resistance. Gastrointestinal conditions that have been linked to Proteus include gastroenteritis (spontaneous and foodborne), nosocomial infections, appendicitis, colonization of devices such as nasogastric tubes, and Crohn's disease. The association of Proteus species with Crohn's disease was particularly strong. Proteus species are low-abundance commensals of the human gut that harbor significant pathogenic potential; further investigation is needed.

Adherent-invasive Escherichia coli in inflammatory bowel disease

Intestinal microbiome dysbiosis has been consistently described in patients with IBD. In the last decades, Escherichia coli, and the adherent-invasive E coli (AIEC) pathotype in particular, has been implicated in the pathogenesis of IBD. Since the discovery of AIEC, two decades ago, progress has been made in unravelling these bacteria characteristics and its interaction with the gut immune system. The mechanisms of adhesion of AIEC to intestinal epithelial cells (via FimH and cell adhesion molecule 6) and its ability to escape autophagy when inside macrophages are reviewed here. We also explore the existing data on the prevalence of AIEC in patients with Crohn's disease and UC, and the association between the presence of AIEC and disease location, activity and postoperative recurrence. Finally, we highlight potential therapeutic strategies targeting AIEC colonisation of gut mucosa, including the use of phage therapy, bacteriocins and antiadhesive molecules. These strategies may open new avenues for the prevention and treatment of IBD in the future.

Metformin protects against intestinal barrier dysfunction via AMPKα1-dependent inhibition of JNK signalling activation

Disruption of the intestinal epithelial barrier, that involves the activation of C‐Jun N‐terminal kinase (JNK), contributes to initiate and accelerate inflammation in inflammatory bowel disease. Metformin has unexpected beneficial effects other than glucose‐lowering effects. Here, we provided evidence that metformin can protect against intestinal barrier dysfunction in colitis. We showed that metformin alleviated dextran sodium sulphate (DSS)‐induced decreases in transepithelial electrical resistance, FITC‐dextran hyperpermeability, loss of the tight junction (TJ) proteins occludin and ZO‐1 and bacterial translocation in Caco‐2 cell monolayers or in colitis mice models. Metformin also improved TJ proteins expression in ulcerative colitis patients with type 2 diabetes mellitus. We found that metformin ameliorated the induction of colitis and reduced the levels of pro‐inflammatory cytokines IL‐6, TNF‐a and IL‐1β. In addition, metformin suppressed DSS‐induced JNK activation, an effect dependent on AMP‐activated protein kinase α1 (AMPKα1) activation. Consistent with this finding, metformin could not maintain the barrier function of AMPKα1‐silenced cell monolayers after DSS administration. These findings highlight metformin protects against intestinal barrier dysfunction. The potential mechanism may involve in the inhibition of JNK activation via an AMPKα1‐dependent signalling pathway.

Dahuang Zexie Decoction Protects against High-Fat Diet-Induced NAFLD by Modulating Gut Microbiota-Mediated Toll-Like Receptor 4 Signaling Activation and Loss of Intestinal Barrier

Increasing evidence suggests that intestinal dysbiosis, intestinal barrier dysfunction, and activated Toll-like receptor 4 (TLR4) signaling play key roles in the pathogenesis of NAFLD. Dahuang Zexie Decoction (DZD) has been verified to be effective for treating NAFLD, but the mechanisms remain unclear. In this study, we investigated the effects of DZD on NAFLD rats and determined whether such effects were associated with change of the gut microbiota, downregulated activity of the TLR4 signaling pathway, and increased expressions of tight junction (TJ) proteins in the gut. Male Sprague Dawley rats were fed high-fat diet (HFD) for 16 weeks to induce NAFLD and then given DZD intervention for 4 weeks. We found that DZD reduced body and liver weights of NAFLD rats, improved serum lipid levels and liver function parameters, and relieved NAFLD. We further found that DZD changed intestinal bacterial communities, inhibited the intestinal TLR4 signaling pathway, and restored the expressions of TJ proteins in the gut. Meanwhile ten potential components of DZD had been identified. These findings suggest that DZD may protects against NAFLD by modulating gut microbiota-mediated TLR4 signaling activation and loss of intestinal barrier. However, further studies are needed to clarify the mechanism by which DZD treats NAFLD.

Comparative genomics of Crohn's disease-associated adherent-invasive Escherichia coli

OBJECTIVE

Adherent-invasive Escherichia coli (AIEC) are a leading candidate bacterial trigger for Crohn's disease (CD). The AIEC pathovar is defined by in vitro cell-line assays examining specific bacteria/cell interactions. No molecular marker exists for their identification. Our aim was to identify a molecular property common to the AIEC phenotype.

DESIGN

41 B2 phylogroup E. coli strains were isolated from 36 Australian subjects: 19 patients with IBD and 17 without. Adherence/invasion assays were conducted using the I-407 epithelial cell line and survival/replication assays using the THP-1 macrophage cell line. Cytokine secretion tumour necrosis factor ((TNF)-α, interleukin (IL) 6, IL-8 and IL-10) was measured using ELISA. The genomes were assembled and annotated, and cluster analysis performed using CD-HIT. The resulting matrices were analysed to identify genes unique/more frequent in AIEC strains compared with non-AIEC strains. Base composition differences and clustered regularly interspaced palindromic repeat (CRISPR) analyses were conducted.

RESULTS

Of all B2 phylogroup strains assessed, 79% could survive and replicate in macrophages. Among them, 11/41 strains (5 CD, 2 UCs, 5 non-IBD) also adhere to and invade epithelial cells, a phenotype assigning them to the AIEC pathovar. The AIEC strains were phylogenetically heterogeneous. We did not identify a gene (or nucleic acid base composition differences) common to all, or the majority of, AIEC. Cytokine secretion and CRISPRs were not associated with the AIEC phenotype.

CONCLUSIONS

Comparative genomic analysis of AIEC and non-AIEC strains did not identify a molecular property exclusive to the AIEC phenotype. We recommend a broader approach to the identification of the bacteria-host interactions that are important in the pathogenesis of Crohn's disease.

Dual role of Helicobacter and Campylobacter species in IBD: a systematic review and meta-analysis

OBJECTIVE

To conduct a comprehensive global systematic review and meta-analysis on the association between Helicobacter pylori infection and IBD. As bacterial antigen cross-reactivity has been postulated to be involved in this association, published data on enterohepatic Helicobacter spp (EHS) and Campylobacter spp and IBD was also analysed.

DESIGN

Electronic databases were searched up to July 2015 for all case-control studies on H. pylori infection/EHS/Campylobacter spp and IBD. Pooled ORs (P-OR) and 95% CIs were obtained using the random effects model. Heterogeneity, sensitivity and stratified analyses were performed.

RESULTS

Analyses comprising patients with Crohn's disease (CD), UC and IBD unclassified (IBDU), showed a consistent negative association between gastric H. pylori infection and IBD (P-OR: 0.43, p value <1e-10). This association appears to be stronger in patients with CD (P-OR: 0.38, p value <1e-10) and IBDU (P-OR: 0.43, p value=0.008) than UC (P-OR: 0.53, p value <1e-10). Stratification by age, ethnicity and medications showed significant results. In contrast to gastric H. pylori, non H. pylori-EHS (P-OR: 2.62, p value=0.001) and Campylobacter spp, in particular C. concisus (P-OR: 3.76, p value=0.006) and C. showae (P-OR: 2.39, p value=0.027), increase IBD risk.

CONCLUSIONS

H. pylori infection is negatively associated with IBD regardless of ethnicity, age, H. pylori detection methods and previous use of aminosalicylates and corticosteroids. Antibiotics influenced the magnitude of this association. Closely related bacteria including EHS and Campylobacter spp increase the risk of IBD. These results infer that H. pylori might exert an immunomodulatory effect in IBD.

Macrophages Versus Escherichia coli: A Decisive Fight in Crohn's Disease

The pathophysiology of Crohn's disease (CD), a chronic inflammatory bowel disease, remains imperfectly elucidated. Consequently, the therapeutic armamentarium remains limited and has not changed the natural history of CD hitherto. Accordingly, physicians need to identify new therapeutic targets to be able to alter the intestinal damage. The most recent hypothesis considered CD as resulting from an abnormal interaction between microbiota and host immune system influenced by genetics and environmental factors. Several experimental and genetic evidence point out intestinal macrophages in CD etiology. An increase of macrophages number and the presence of granulomas are especially observed in the intestinal mucosa of patients with CD. These macrophages could be defective and particularly in responses to infectious agents like CD-associated Escherichia coli. This review focuses on, what is currently known regarding the role of macrophages, macrophages/E. coli interaction, and the impact of CD therapies on macrophages in CD. We also speculate that macrophages modulation could lead to important translational implications in CD with the end goal of promoting gut health.

The predominant site of bacterial translocation across the intestinal mucosal barrier occurs at the advancing disease margin in Crohn's disease

Crohn's disease is characterized by increased permeability of the intestinal mucosal barriers and an abnormal or dysregulated immune response to specific and/or commensal bacteria arising from the intestinal lumen. To determine the types of bacteria that are transgressing the mucosal barrier and colonizing the intestinal submucosal tissues, we performed 16S rRNA gene microbiota sequencing of the submucosal and mucosal tissues at the advancing disease margin in ileal Crohn's disease. Microbial populations were compared between mucosa and submucosa and non-inflammatory bowel disease (non-IBD) controls, as well as to microbial populations previously found at the centre of the disease lesion. There was no significant increase in bacteria within the submucosa of non-IBD controls at any taxonomic level when compared to the corresponding superjacent mucosa, indicating an effective mucosal barrier within the non-IBD population. In contrast, there was a statistically significant increase in 13 bacterial families and 16 bacterial genera within the submucosa at the advancing disease margin in Crohn's disease when compared to the superjacent mucosa. Major increases within the submucosa included bacteria of the Families Sphingomonadaceae, Alicyclobacillaceae, Methylobacteriaceae, Pseudomonadaceae and Prevotellaceae. Data suggest that the primary site of bacterial translocation across the mucosal barrier occurs at the margin between diseased and normal tissue, the advancing disease margin. The heterogeneity of the bacterial populations penetrating the mucosal barrier and colonizing the submucosal intestinal tissues and, therefore, contributing to the inflammatory processes, suggests that bacterial translocation is secondary to a primary event leading to a breakdown of the mucosal barrier.

Gut microbiota translocation to the pancreatic lymph nodes triggers NOD2 activation and contributes to T1D onset

Streptozotocin causes T1D by inducing the translocation of intestinal bacteria into pancreatic lymph nodes and driving the development of pathogenic Th1 and Th17 cells through NOD2 receptor.

Type 1 diabetes (T1D) is an autoimmune disease that is triggered by both genetic and environmental factors, resulting in the destruction of pancreatic β cells. The disruption of the intestinal epithelial barrier and consequent escape of microbial products may be one of these environmental triggers. However, the immune receptors that are activated in this context remain elusive. We show here that during streptozotocin (STZ)-induced T1D, the nucleotide-binding oligomerization domain containing 2 (NOD2), but not NOD1, participates in the pathogenesis of the disease by inducing T helper 1 (Th1) and Th17 cells in the pancreatic LNs (PLNs) and pancreas. Additionally, STZ-injected wild-type (WT) diabetic mice displayed an altered gut microbiota compared with vehicle-injected WT mice, together with the translocation of bacteria to the PLNs. Interestingly, WT mice treated with broad-spectrum antibiotics (Abx) were fully protected from STZ-induced T1D, which correlated with the abrogation of bacterial translocation to the PLNs. Notably, when Abx-treated STZ-injected WT mice received the NOD2 ligand muramyl dipeptide, both hyperglycemia and the proinflammatory immune response were restored. Our results demonstrate that the recognition of bacterial products by NOD2 inside the PLNs contributes to T1D development, establishing a new putative target for intervention during the early stages of the disease.

Role of intestinal microbiota and fecal microbiota transplantation in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, non-specific inflammatory disease which mainly comprises Crohn's disease (CD) and ulcerative colitis (UC). Their etiologies and pathogenesis are still unclear. The role of gut microbiota in IBD has been gradually recognized in recent years. Two specific microorganisms (Mycobacterium avium subspecies paratuberculosis and Escherichia coli) were more widely studied. The microbiota also provides new therapeutic methods. Fecal microbiota transplantation (FMT) may restore the balance of intestinal flora to supplement or optimize current therapies. This article reviews the role and application of intestinal microbiota and FMT in IBD.

GipA Factor Supports Colonization of Peyer's Patches by Crohn's Disease-associated Escherichia Coli

BACKGROUND

Adherent-invasive Escherichia coli (AIEC) associated with Crohn's disease target M cells lining Peyer's patches (PPs) through the expression of long polar fimbriae (LPF) and survive macrophage killing. Invasion of PPs constitutes a way to colonize the mucosa for bacteria able to escape or resist killing of underlying immune cells. We aimed to identify new virulence factors involved in PPs colonization by AIEC.

METHODS

The presence of gipA (Growth in PPs) gene was determined by polymerase chain reaction. In vivo experiments were performed using CEABAC10 transgenic mice. Intramacrophagic behavior of AIEC was assessed in murine bone marrow-derived macrophages and human monocyte-derived macrophages. Cytokines production was quantified by ELISA.

RESULTS

A higher prevalence of gipA-positive E. coli was observed in patients with Crohn's disease (27.3%) compared with controls (17.2%). Unlike non-AIEC strains, all gipA-positive AIEC strains also harbored lpfA. GipA deletion impaired AIEC translocation across M cells and their replication inside macrophages. GipA expression was induced by gastrointestinal (bile salts) and phagolysosomal (reactive oxygen species and acid pH) conditions. GipA deletion decreased lpfA mRNA level in AIEC bacteria. Survival of AIEC-ΔgipA bacteria was reduced in medium containing H2O2 or acidic pH. GipA deletion impaired AIEC colonization of PPs and dissemination to mesenteric lymph nodes in mice.

CONCLUSIONS

GipA is required for optimal colonization of mouse PPs and survival within macrophages by AIEC, suggesting that this factor plays a role in AIEC promotion of Crohn's disease. Detection of gipA and lpfA could be a predictor for the presence of AIEC.

Global Epidemiology of Campylobacter Infection

Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Changes in the composition of intestinal fungi and their role in mice with dextran sulfate sodium-induced colitis

Intestinal fungi are increasingly believed to greatly influence gut health. However, the effects of fungi on intestinal inflammation and on gut bacterial constitution are not clear. Here, based on pyrosequencing method, we reveal that fungal compositions vary in different intestinal segments (ileum, cecum, and colon), prefer different colonization locations (mucosa and feces), and are remarkably changed during intestinal inflammation in dextran sulfate sodium (DSS)-colitis mouse models compare to normal controls: Penicillium, Wickerhamomyces, Alternaria, and Candida are increased while Cryptococcus, Phialemonium, Wallemia and an unidentified Saccharomycetales genus are decreased in the guts of DSS-colitis mice. Fungi-depleted mice exhibited aggravated acute DSS-colitis associated with gain of Hallella, Barnesiella, Bacteroides, Alistipes, and Lactobacillus and loss of butyrate-producing Clostridium XIVa, and Anaerostipes compare with normal control. In contrast, bacteria-depleted mice show attenuated acute DSS-colitis. Mice with severely chronic recurrent DSS-colitis show increased plasma (1,3)-β-D-glucan level and fungal translocation into the colonic mucosa, mesenteric lymph nodes and spleen. This work demonstrate the different roles of fungi in acute and chronic recurrent colitis: They are important counterbalance to bacteria in maintaining intestinal micro-ecological homeostasis and health in acutely inflamed intestines, but can harmfully translocate into abnormal sites and could aggravate disease severity in chronic recurrent colitis.

The impact of bacterial DNA translocation on early postoperative outcomes in Crohn's patients undergoing abdominal surgery

BACKGROUND AND AIMS

Bacterial DNA (bactDNA) translocation occurs frequently in patients with Crohn's disease and can be present in patients with a negative blood microbiological culture. We aimed to determine the effects of bactDNA translocation on postoperative outcomes in Crohn's disease patients undergoing abdominal surgery.

METHODS

Patients with Crohn's disease who underwent abdominal surgery between January 2012 and March 2014 were identified. General and postoperative outcome-related information was retrieved from a database, and the data were compared between patients with and without bactDNA translocation. Multivariate analysis was used to determine the independent effect of bactDNA translocation on postoperative morbidity.

RESULTS

One hundred and seven patients who underwent abdominal surgery were included in our study. The presence of bactDNA in blood samples was identified in 29 patients (27.1%). There was a total of 55 complications in 28 patients (26.2%). Patients with bactDNA in their blood had a mean postoperative hospital stay of 12.7±4.2 days and patients without DNA translocation had a mean postoperative hospital stay of 10.1±4.8 days (p = 0.009). The readmission rate was increased in patients with bactDNA translocation (p = 0.032). A low preoperative level of serum albumin (p = 0.024), preoperative immunosuppressive agent use (p = 0.046), and the presence of bactDNA in blood (p = 0.005) were independently associated with increased postoperative adverse outcomes.

CONCLUSIONS

Preoperative bactDNA translocation into the blood increases the incidence of postoperative adverse outcomes in patients with Crohn's disease who undergo abdominal surgery.

Pathogenesis of Crohn’s disease: Bug or no bug

The possibility of an infectious origin in inflammatory bowel disease (IBD) has been postulated since the first description of Crohn’s disease (CD). Many observations implicate bacteria as a trigger for the development of CD: lesions occur in regions with higher bacterial concentrations; aphthous ulcers occur in Peyer’s patches; inflammation resolves when the fecal stream is diverted and is reactivated following reinfusion of bowel contents; severity of the disease is correlated with bacterial density in the mucosa; granulomas can contain bacteria; and susceptible mice raised in germ-free conditions develop inflammation when bacteria are introduced in the 1990’s, several studies sought to establish a relationship with viral infections and the onset of IBD, finally concluding that no direct link had been demonstrated. In the past fifteen years, evidence relating IBD pathogenesis to Mycobacterium avium paratuberculosis, salmonella, campylobacter, etc., has been found. The tendency now under discussion to regard microbiota as the primary catalyst has led to the latest studies on microbiota as pathogens, focusing on Escherichia coli, mainly in ileal CD. The present review discusses the literature available on these “bugs”.

Anatomical localization of commensal bacteria in immune cell homeostasis and disease

The mammalian gastrointestinal (GI) tract is colonized by trillions of beneficial commensal bacteria that are essential for promoting normal intestinal physiology. While the majority of commensal bacteria are found in the intestinal lumen, many species have also adapted to colonize different anatomical locations in the intestine, including the surface of intestinal epithelial cells (IECs) and the interior of gut-associated lymphoid tissues. These distinct tissue localization patterns permit unique interactions with the mammalian immune system and collectively influence intestinal immune cell homeostasis. Conversely, dysregulated localization of commensal bacteria can lead to inappropriate activation of the immune system and is associated with numerous chronic infectious, inflammatory, and metabolic diseases. Therefore, regulatory mechanisms that control proper anatomical containment of commensal bacteria are essential to maintain tissue homeostasis and limit pathology. In this review, we propose that commensal bacteria associated with the mammalian GI tract can be anatomically defined as (i) luminal, (ii) epithelial-associated, or (iii) lymphoid tissue-resident, and we discuss the role and regulation of these microbial populations in health and disease.

Understanding host-adherent-invasive Escherichia coli interaction in Crohn's disease: opening up new therapeutic strategies

A trillion of microorganisms colonize the mammalian intestine. Most of them have coevolved with the host in a symbiotic relationship and some of them have developed strategies to promote their replication in the presence of competing microbiota. Recent evidence suggests that perturbation of the microbial community favors the emergence of opportunistic pathogens, in particular adherent-invasive Escherichia coli (AIEC) that can increase incidence and severity of gut inflammation in the context of Crohn's disease (CD). This review will report the importance of AIEC as triggers of intestinal inflammation, focusing on their impact on epithelial barrier function and stimulation of mucosal inflammation. Beyond manipulation of immune response, restoration of gut microbiota as a new treatment option for CD patients will be discussed.

Role of the intestinal microbiota and fecal transplantation in inflammatory bowel diseases

Ulcerative colitis and Crohn's disease are the two major types of inflammatory bowel disease (IBD). Despite intensive study, it is still challenging because the precise etiology and pathogenesis remains unclear. Studies have shown that IBD is associated with changes in the composition of intestinal microbiota, as either a cause or a consequence of abnormal host immune response in genetic susceptible population. Two specific microorganisms (Mycobacterium avium subsp. paratuberculosis and Escherichia coli) get more widely studied, but till now no single microorganism has been identified as the only pathogen. Genetic susceptibility data also suggest impaired handling of bacteria as well as an improper immune response to potential pathogens. The microbiota provides new therapeutic methods, and fecal microbiota transplantation may restore the balance of intestinal flora to supplement or optimize the current therapies.

Escherichia coli in chronic inflammatory bowel diseases: An update on adherent invasive Escherichia coli pathogenicity

Escherichia coli (E. coli), and particularly the adherent invasive E. coli (AIEC) pathotype, has been increasingly implicated in the ethiopathogenesis of Crohn’s disease (CD). E. coli strains with similar pathogenic features to AIEC have been associated with other intestinal disorders such as ulcerative colitis, colorectal cancer, and coeliac disease, but AIEC prevalence in these diseases remains largely unexplored. Since AIEC was described one decade ago, substantial progress has been made in deciphering its mechanisms of pathogenicity. However, the molecular bases that characterize the phenotypic properties of this pathotype are still not well resolved. A review of studies focused on E. coli populations in inflammatory bowel disease (IBD) is presented here and we discuss about the putative role of this species on each IBD subtype. Given the relevance of AIEC in CD pathogenesis, we present the latest research findings concerning AIEC host-microbe interactions and pathogenicity. We also review the existing data regarding the prevalence and abundance of AIEC in CD and its association with other intestinal diseases from humans and animals, in order to discuss the AIEC disease- and host-specificity. Finally, we highlight the fact that dietary components frequently found in industrialized countries may enhance AIEC colonization in the gut, which merits further investigation and the implementation of preventative measures.