Canonical and atypical chemokine receptors in the neutrophil life cycle.

Chemokines are mainly studied for their local function in the control of leukocyte extravasation in homeostatic and inflammatory conditions. However, they have additional roles at the systemic level including the regulation of the hematopoietic process and leukocyte differentiation. Due to the redundancy and pleiotropicity of the chemokine system, chemokines have often multiple and complex roles in neutrophil differentiation ranging from retention and control of proliferation of progenitors to the mobilization of mature cells from the bone marrow (BM) to the bloodstream and their further differentiation in tissues. Atypical chemokine receptors (ACKRs) are regulators of the chemokine system by controlling chemokine bioavailability and chemokine receptor function. Even though ACKRs bind a wide range of chemokines, they appear to have a selective role in the process of neutrophil production and differentiation. The aim of this review is to give an overview of the current evidence regarding the role of chemokines and chemokine receptors in the life of neutrophils with a focus on the regulation exerted by ACKRs.

miR-21 sustains CD28 signalling and low-affinity T-cell responses at the expense of self-tolerance.

OBJECTIVE: miR-21 is highly expressed in iNKT and activated T cells, but its T-cell autonomous functions are poorly defined. We sought to investigate the role of miR-21 in the development and functions of T and iNKT cells, representing adaptive and innate-like populations, respectively. METHODS: We studied mice with a conditional deletion of miR-21 in all mature T lymphocytes. RESULTS: Thymic and peripheral T and iNKT compartments were normal in miR-21 KO mice. Upon activation in vitro, miR-21 depletion reduced T-cell survival, TH17 polarisation and, remarkably, T- and iNKT cell ability to respond to low-affinity antigens, without altering their response to high-affinity ones. Mechanistically, miR-21 sustained CD28-dependent costimulation pathways required to lower the T-cell activation threshold, inhibiting its repressors in a positive feedback circuit, in turn increasing T-cell sensitivity to antigenic stimulation and survival. Upon immunisation with the low-affinity self-epitope MOG35-55, miR-21 KO mice were indeed less susceptible than WT animals to the induction of experimental autoimmune encephalomyelitis, whereas they mounted normal T-cell responses against high-affinity viral epitopes generated upon lymphocytic choriomeningitis virus infection. CONCLUSION: The induction of T-cell responses to weak antigens (signal 1) depends on CD28 costimulation (signal 2). miR-21 sustains CD28 costimulation, decreasing the T-cell activation threshold and increasing their sensitivity to antigenic stimulation and survival, broadening the immune surveillance range. This occurs at the cost of unleashing autoimmunity, resulting from the recognition of weak self-antigens by autoreactive immune responses. Thus, miR-21 fine-tunes T-cell response and self-/non-self-discrimination.

Multiple Roles for Chemokines in Neutrophil Biology.

Chemokines are recognized as the most critical mediators for selective neutrophil recruitment during inflammatory conditions. Furthermore, they are considered fundamental regulators of neutrophil mobilization from the bone marrow (BM) to the bloodstream and for their homing back at the end of their life for apoptosis and clearance. However, chemokines are also important mediators of neutrophil effector functions including oxidative burst, degranulation, neutrophil extracellular trap (NET)osis, and production of inflammatory mediators. Neutrophils have been historically considered as a homogeneous population. In recent years, several maturation stages and subsets with different phenotypic profiles and effector functions were described both in physiological and pathological conditions such as infections, autoimmunity, and cancer. The aim of this review is to give an overview of the current evidence regarding the role of chemokines and chemokine receptors in neutrophil biology, including their possible role in neutrophil maturation, differentiation, and in defining emerging neutrophil subsets.

The Spectrum of Small Intestinal Lesions in Patients with Unexplained Iron Deficiency Anemia Detected by Video Capsule Endoscopy.

Background and objectives: Video-capsule endoscopy (VCE) has shown a large range (38⁻83%) of diagnostic yield in unexplained iron deficiency anemia (IDA) and obscure-occult bleeding. Therefore, we retrospectively investigated the VCE-detected spectrum and the prevalence of small bowel injuries and associated risk factors in inpatients with both of the above reported conditions. Methods: We selected inpatients with IDA (hemoglobin <12 g/dL in women, <13 g/dL in men) and obscure-occult bleeding. We excluded VCE indications other than IDA. Complete medical histories and laboratory tests were collected. All subjects underwent PillCam SB2/SB3. The VCE feature Lewis score was calculated when appropriate. We used the t-test and Fisher's exact test for continuous and categorical variables, respectively, in univariate analysis. For multivariate analysis, we used binomial logistic regression. Results: We retrieved 109 patients (female:male ratio of 53:56; age 63.4 ± 18.9 years). Eighty patients (73.4%) showed ≥1 small bowel lesions. The Lewis score was calculated in 41 patients: 13 (31.7%) showed a mild (<135) and 28 (68.3%) a moderate-severe (135⁻790 and >790, respectively) score. In univariate analysis, the small bowel transit time (6.2 ± 2.9 versus 5.2 ± 2.1 h; p = 0.049) and non-steroidal anti-inflammatory drug use for at least two weeks (17.5% versus 0%; p = 0.01) were significantly higher in subjects with injuries. These associations were not confirmed at multivariate analysis. The severity of a lesion directly correlated with proton pump inhibitor (PPI) use and duration (not confirmed in multivariate analysis). VCE can reveal the source of obscure-occult bleeding in a high percentage of unexplained IDAs. A wide spectrum of endoscopic pictures may be found. Known as well as supposed risk factors for small bowel lesions may be detected.

Nonalcoholic Fatty Liver Disease in Inflammatory Bowel Disease: Prevalence and Risk Factors.

Background: Nonalcoholic fatty liver disease (NAFLD) is common in inflammatory bowel diseases (IBD). Herein, NAFLD prevalence and risk factors in a large IBD cohort were evaluated and compared to that of a non-IBD sample. Methods: Crohn's disease/ulcerative colitis outpatients referred to IBD service of our Gastroenterology Unit were enrolled. Subjects affected by functional and motor gastrointestinal disorders, in whom IBD was ruled out, referred to general outpatient service in the same area, were considered as nonIBD group. Exclusion criteria were based on previous diagnosis of nonNAFLD chronic liver diseases and secondary causes of fat liver overload. Characteristics of IBD and liver status were collected. Risk factors for metabolic syndrome were analyzed. Ultrasonographic presence and degree of steatosis were assessed. Data were examined by univariate and multivariate analyses. Results: For this study 465 IBD and 189 non-IBD subjects were consecutively enrolled. NAFLD was found in 28.0% and 20.1% in IBD and non-IBD subjects, respectively (P = 0.04). IBD patients with NAFLD were younger than non-IBD ones. There was no significant difference in steatosis grade and association between NAFLD and IBD behavior, extension, activity, and drugs. In the IBD group, multivariate analysis demonstrated that NAFLD was independently associated to metabolic syndrome (OR=2.24, 95%CI 1.77-28.81), diabetes (OR=1.71, 95%CI 1.43-12.25), fasting blood glucose (OR=1.36, 95%CI 1.13-1.68), and abdominal circumference (OR=1.68, 95%CI 1.15-14.52). Conclusions: NAFLD is more common and occurs at a younger age in IBD than in nonIBD subjects. However, further investigation is required to ascertain possible NAFLD pathogenic IBD-related factors other than conventional/metabolic ones. 10.1093/ibd/izy051_video1izy051.video15774874877001.

Endothelial function and cardiovascular risk in active inflammatory bowel diseases.

BACKGROUND: Endothelial dysfunction has been already reported in inflammatory bowel diseases (IBD). However, case series so far examined were rather heterogeneous as for disease severity and subsets investigated. OBJECTIVE: We evaluated endothelial dysfunction by brachial artery flow-mediated vasodilatation (FMD), and subclinical atherosclerosis by assessment of common carotid intima-media thickness (CCA-IMT) in a cohort of patients with Crohn's disease (CD) or Ulcerative colitis (UC) in active phase compared to healthy control subjects. METHODS: Forty-nine patients (mean age 41±16 years), 25 with CD and 23 with UC, and forty controls (mean age 45±15 years) were enrolled. Diagnosis was based on the standard clinical, endoscopic and histological criteria. Disease activity was assessed by Crohn's Disease Activity Index or Disease Activity Index. All patients, were under medical treatment as appropriate. RESULTS: FMD values were lower in IBD patients than controls (6.1±3.0 vs 8.2±3.4. p=0.003); no difference was seen between UC/CD groups (5.9±3.5 vs 6.3±2.6, p=0.67). No changes in statistical differences occurred after adjustment for age, gender, body mass index and family history of cardiovascular disease. Finally, no differences in IMT values were seen between IBD patients and controls. Disease duration and medical treatment did not affect endothelial function. CONCLUSIONS: Our study showed a lower FMD in IBD patients. Inflammation and immune response could explain endothelial dysfunction, which is the earliest stage of atherosclerotic process. IBD patients in active phase might therefore be at higher risk for atherosclerosis progression.

Dietary, endocrine, and metabolic factors in the development of colorectal cancer.

INTRODUCTION: Colorectal cancer is the third cause of death in industrialized countries. Genetic susceptibility and diet are determinant of cancer risk and tumor behavior. Variation in cancer incidence among and within populations with similar dietary patterns suggests that an individual response may reflect interactions with genetic factors, which may modify gene, protein, and metabolite expression patterns. Nutrigenomics, defined as the interaction between nutrition and an individual genome, will likely provide important clues about responders and non-responders to nutritional intervention. DISCUSSION: Epidemiological and experimental studies suggest a protective role of some normal components of daily diet (fish oil, milk, and vegetables), estrogens, and phytoestrogens in colorectal cancer. The effect of estrogen seems to be mediated by their binding to estrogen receptor beta (ER-ß), one of the two estrogen receptors with high affinity for these hormones. Very recently, the demonstration of an involvement of ER-ß in the development of adenomatous polyps of the colon has also been documented, suggesting the use of selective ER-ß agonists in primary colorectal cancer prevention. Phytoestrogens are plant-derived compounds that structurally and functionally act as estrogen agonists in mammals. They are characterized by a higher binding affinity to ER-ß as compared to estrogen receptor alpha (ER-α), the other estrogen receptor subtype. These biological characteristics explain why the administration of phytoestrogens does not produce the classical side effects associated to estrogen administration (cerebro- and cardiovascular accidents, higher incidence of endometrial and breast cancer) and makes these substances potential candidates for colorectal cancer prevention.