Role and mechanisms of action of escherichia coli nissle 1917 in the maintenance of remission in ulcerative colitis patients: an update

Ulcerative colitis (UC) is a chronic inflammatory disease, whose etiology is still unclear. Its pathogenesis involves an interaction between genetic factors, immune response and the “forgotten organ”, Gut Microbiota. Several studies have been conducted to assess the role of antibiotics and probiotics as additional or alternative therapies for Ulcerative Colitis. Escherichia coli Nissle (EcN) is a nonpathogenic Gram-negative strain isolated in 1917 by Alfred Nissle and it is the active component of microbial drug Mutaflor® (Ardeypharm GmbH, Herdecke, Germany and EcN, Cadigroup, In Italy) used in many gastrointestinal disorder including diarrhea, uncomplicated diverticular disease and UC. It is the only probiotic recommended in ECCO guidelines as effective alternative to mesalazine in maintenance of remission in UC patients. In this review we propose an update on the role of EcN 1917 in maintenance of remission in UC patients, including data about efficacy and safety. Further studies may be helpful for this subject to further the full use of potential of EcN.

Anti-tumor necrosis factor α therapy associates to type 17 helper T lymphocytes immunological shift and significant microbial changes in dextran sodium sulphate colitis

BACKGROUND Anti-tumor necrosis factor α(TNFα) represents the best therapeutic option to induce mucosal healing and clinical remission in patients with moderate-severe ulcerative colitis. On the other side gut microbiota plays a crucial role in pathogenesis of ulcerative colitis but few information exists on how microbiota changes following anti-TNFα therapy and on microbiota role in mucosal healing.AIM To elucidate whether gut microbiota and immune system changes appear following anti TNFα therapy during dextran sulfate sodium(DSS) colitis.METHODS Eighty C57 BL/6 mice were divided into four groups: "No DSS", "No DSS + antiTNFα", "DSS" and "DSS + anti-TNFα". "DSS" and "DSS + anti-TNFα" were treated for 5 d with 3% DSS. At day 3, mice whithin "No DSS+anti-TNFα" and"DSS+anti-TNFα" group received 5 mg/kg of an anti-TNFα agent. Forty mice were sacrificed at day 5, forty at day 12, after one week of recovery post DSS. The severity of colitis was assessed by a clinical score(Disease Activity Index), colon length and histology. Bacteria such as Bacteroides, Clostridiaceae, Enterococcaceae and Fecalibacterium prausnitzii(F. prausnitzii) were evaluated by quantitative PCR.Type 1 helper T lymphocytes(Th1), type 17 helper T lymphocytes(Th17) and CD4+ regulatory T lymphocytes(Treg) distributions in the mesenteric lymph node(MLN) were studied by flow cytometry.RESULTS Bacteria associated with a healthy state(i.e., such as Bacteroides, Clostridiaceae and F. prausnitzii) decreased during colitis and increased in course of anti-TNFαtreatment. Conversely, microorganisms belonging to Enterococcaceae genera,which are linked to inflammatory processes, showed an opposite trend.Furthermore, in colitic mice treated with anti-TNFα microbial changes were associated with an initial increase(day 5 of the colitis) in Treg cells and a consequent decrease(day 12 post DSS) in Th1 and Th17 frequency cells. Healthy mice treated with anti-TNFα showed the same histological, microbial and immune features of untreated colitic mice. "No DSS + anti-TNFα" group showed a lymphomononuclear infiltrate both at 5 th and 12 th d at hematoxylin and eosin staining, an increase of in Th1 and Th17 frequency at day 12, an increase of Enterococcaceae at day 5, a decrease of Bacteroides and Clostridiaceae at day 12.CONCLUSION Anti-TNFα treatment in experimental model of colitis improves disease activity but it is associated to an increase in Th17 pathway together with gut microbiota alteration.

Infliximab does not increase colonic cancer risk associated to murine chronic colitis

AIM To explore the influence of Infliximab(IFX) on cancer progression in a murine model of colonic cancer associated to chronic colitis.METHODS AOM/DSS model was induced in C57BL/6 mice. Mice were injected with IFX(5 mg/kg) during each DSS cycle while control mice received saline. Body weight, occult blood test and stool consistency were measured to calculate the disease activity index(DAI). Mice were sacrificed at week 10 and colons were analyzed macroscopically and microscopically for number of cancers and degree of inflammation. MTT assay was performed on CT26 to evaluate the potential IFX role on metabolic activity and proliferation. Cells were incubated with TNF-α or IFX or TNF-α plus IFX, and cell vitality was evaluated after 6, 24 and 48 h. The same setting was used after pre-incubation with TNF-α for 24 h.RESULTS IFX significantly reduced DAI and body weight loss in mice compared with controls, preserving also colon length at sacrifice. Histological score was also reduced in treated mice. At macroscopic analysis, IFX treated mice showed a lower number of tumor lesions compared to controls. This was confirmed at microscopic analysis, although differences were not statistically significant. In vitro, IFX treated CT26 maintained similar proliferation ability at MTT test, both when exposed to IFX alone and when associated to TNF-α.CONCLUSION IFX did not increase colonic cancer risk in AOM-DSS model of cancer on chronic colitis nor influence directly the proliferation of murine colon cancer epithelial cells.