Antonio Di Sabatino

Post-splenectomy and hyposplenic states

The spleen is crucial in regulating immune homoeostasis through its ability to link innate and adaptive immunity and in protecting against infections. The impairment of splenic function is defined as hyposplenism, an acquired disorder caused by several haematological and immunological diseases. The term asplenia refers to the absence of the spleen, a condition that is rarely congenital and mostly post-surgical. Although hyposplenism and asplenia might predispose individuals to thromboembolic events, in this Review we focus on infectious complications, which are the most widely recognised consequences of these states. Because of the high mortality, the fulminant course, and the refractoriness to common treatment of overwhelming infections caused by encapsulated bacteria, prevention through vaccination and antibiotic prophylaxis is the basis of the management of patients who have had splenectomy or have hyposplenism. In this Review, we critically assess clinical and diagnostic aspects of splenic dysfunction and highlight new perspectives in the prevention of overwhelming post-splenectomy infections.

Innate and adaptive immunity in inflammatory bowel disease

Inflammatory bowel disease (IBD) includes Crohns disease (CD) and ulcerative colitis (UC). The exact cause of IBD remains unknown. Available evidence suggests that an abnormal immune response against the microorganisms of the intestinal flora is responsible for the disease in genetically susceptible individuals. The adaptive immune response has classically been considered to play a major role in the pathogenesis of IBD. However, recent advances in immunology and genetics have clarified that the innate immune response is equally as important in inducing gut inflammation in these patients. In particular, an altered epithelial barrier function contributes to intestinal inflammation in patients with UC, while aberrant innate immune responses, such as antimicrobial peptide production, innate microbial sensing and autophagy are particularly associated to CD pathogenesis. On the other hand, besides T helper cell type (Th)1 and Th2 immune responses, other subsets of T cells, namely Th17 and regulatory T (Treg) cells, are likely to play a role in IBD. However, given the complexity and probably the redundancy of pathways leading to IBD lesions, and the fact that Th17 cells may also have protective functions, neutralization of IL-17A failed to induce any improvement in CD. Studying the interactions between various constituents of the innate and adaptive immune systems will certainly open new horizons in the knowledge about the immunologic mechanisms implicated in gut inflammation.

Mongersen, an Oral SMAD7 Antisense Oligonucleotide, and Crohn’s Disease

BACKGROUND Crohns disease-related inflammation is characterized by reduced activity of the immunosuppressive cytokine transforming growth factor β1 (TGF-β1) due to high levels of SMAD7, an inhibitor of TGF-β1 signaling. Preclinical studies and a phase 1 study have shown that an oral SMAD7 antisense oligonucleotide, mongersen, targets ileal and colonic SMAD7. METHODS In a double-blind, placebo-controlled, phase 2 trial, we evaluated the efficacy of mongersen for the treatment of persons with active Crohns disease. Patients were randomly assigned to receive 10, 40, or 160 mg of mongersen or placebo per day for 2 weeks. The primary outcomes were clinical remission at day 15, defined as a Crohns Disease Activity Index (CDAI) score of less than 150, with maintenance of remission for at least 2 weeks, and the safety of mongersen treatment. A secondary outcome was clinical response (defined as a reduction of 100 points or more in the CDAI score) at day 28. RESULTS The proportions of patients who reached the primary end point were 55% and 65% for the 40-mg and 160-mg mongersen groups, respectively, as compared with 10% for the placebo group (P<0.001). There was no significant difference in the percentage of participants reaching clinical remission between the 10-mg group (12%) and the placebo group. The rate of clinical response was significantly greater among patients receiving 10 mg (37%), 40 mg (58%), or 160 mg (72%) of mongersen than among those receiving placebo (17%) (P=0.04, P<0.001, and P<0.001, respectively). Most adverse events were related to complications and symptoms of Crohns disease. CONCLUSIONS We found that study participants with Crohns disease who received mongersen had significantly higher rates of remission and clinical response than those who received placebo. (Funded by Giuliani; EudraCT number, 2011-002640-27.).

Dendritic cells in intestinal homeostasis and disease.

DCs are specialized APCs that orchestrate innate and adaptive immune responses. The intestinal mucosa contains numerous DCs, which induce either protective immunity to infectious agents or tolerance to innocuous antigens, including food and commensal bacteria. Several subsets of mucosal DCs have been described that display unique functions, dictated in part by the local microenvironment. In this review, we summarize the distinct subtypes of DCs and their distribution in the gut; examine how DC dysfunction contributes to intestinal disease development, including inflammatory bowel disease and celiac disease; and discuss manipulation of DCs for therapy.

Prevalence and pathogenesis of anemia in inflammatory bowel disease. Influence of anti-tumor necrosis factor-α treatment

Background Anemia is a common complication of inflammatory bowel disease, but its epidemiology may be changing due to earlier diagnosis and improved treatments. We investigated the prevalence and pathogenesis of anemia in patients with inflammatory bowel disease. Design and Methods In a cross-sectional study 263 out-patients with inflammatory bowel disease (165 with Crohn’s disease, 98 with ulcerative colitis) were investigated. The influence of time from diagnosis, disease activity, inflammation and the status of iron and hematinic vitamins on the level of hemoglobin and prevalence of anemia were evaluated. In a second group of 27 patients with Crohn’s disease, undergoing anti-tumor necrosis factor-α treatment with infliximab because of refractory or fistulizing disease, we determined the effects of infliximab on disease activity, hemoglobin, serum erythropoietin levels, iron status and inflammation. Results In all, 104 of the 263 patients with inflammatory bowel disease were anemic. Age, gender and azathioprine treatment had no influence on anemia. The prevalence of anemia was highest at diagnosis (65%), decreased during the first 4 years after disease onset, and was stable thereafter. Active disease was associated with higher rates of anemia. At diagnosis most anemic patients had anemia of chronic disease; during follow-up iron deficiency and multifactorial forms of anemia became more prevalent. Eighteen of 27 patients undergoing treatment with infliximab were anemic; most of them had anemia of chronic disease. Infliximab reduced disease activity and improved anemia in 12 patients. This was mediated by an increased production of erythropoietin for the degree of anemia. In vitro infliximab increased the growth of erythroid progenitors from the peripheral blood of patients with active disease. Conclusions Anemia is a common problem in out-patients with inflammatory bowel disease; the prevalence and severity of anemia are related to the activity of the bowel disorder. The pathogenesis of anemia changes during the course of the disease, with anemia of chronic disease having a major role at diagnosis and iron deficiency and multifactorial forms of anemia during follow-up. In patients requiring anti-tumor necrosis factor-α treatment, response to therapy improves erythropoiesis.

Prophylaxis of ERCP-related pancreatitis: A randomized, controlled trial of somatostatin and gabexate mesylate

BACKGROUND & AIMS It still is debated whether post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis can be prevented by administering either somatostatin or gabexate mesylate. The aim of the study is to assess the efficacy of a 6.5-hour infusion of somatostatin or gabexate mesylate in preventing ERCP-related complications. METHODS In a double-blind multicenter trial, 1127 patients undergoing ERCP were randomly assigned to intravenous administration of somatostatin (750 microg; n = 351), gabexate mesylate (500 mg; n = 381), or placebo (saline; n = 395). The drug infusion started 30 minutes before and continued for 6 hours after endoscopy. Patients were evaluated clinically, and serum amylase levels were determined at 4, 24, and 48 hours after endoscopy. RESULTS No significant differences in incidences of pancreatitis, hyperamylasemia, or abdominal pain were observed among the placebo (4.8%, 32.6%, and 5.3%, respectively), somatostatin (6.3%, 26.8%, and 5.1%, respectively), and gabexate mesylate groups (5.8%, 31.5%, and 6.3%, respectively). Univariate analysis of patient characteristics and endoscopic maneuvers showed that a Freeman score >1 (P < 0.0001), >/=3 pancreatic injections (P < 0.00001), and precut sphincterotomy (P = 0.01) were significantly associated with post-ERCP pancreatitis. At multiple logistic regression analysis, >/=3 pancreatic injections (odds ratio [OR], 1.95; 95% confidence interval [CI], 1.45-2.63) and a Freeman score >1 (OR, 1.47; 95% CI, 1.11-1.94) retained their predictive power. CONCLUSIONS Long-term (6.5-hr) administration of either somatostatin or gabexate mesylate is ineffective for the prevention of post-ERCP pancreatitis. Pancreatic injury seems to be related to difficulty in common bile duct access.

Increased Enterocyte Apoptosis and Fas-Fas Ligand System in Celiac Disease

Our aim was to evaluate whether increased enterocyte apoptosis was responsible for mucosal flattening in celiac disease (CD), and, since the mechanisms responsible for tissue injury in this condition are unknown, we studied the possibility that the Fas-Fas ligand (FasL) system may be involved. Endoscopic duodenal biopsy specimens from 12 patients with untreated and 12 with treated CD and 12 control subjects were evaluated for enterocyte apoptosis by the terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine triphosphate nick-end labeling assay and for Fas and FasL expression by immunohistochemistry. A coculture of isolated enterocytes (targets) and purified lamina propria mononuclear cells (LPMCs) (effectors) was performed in the absence or presence of an antagonistic ZB4 anti-Fas antibody. We found a significant correlation between the degree of villous atrophy, morphometrically evaluated, and the level of enterocyte apoptosis, suggesting that mucosal flattening is a consequence of exaggerated epithelial cell death. Most celiac enterocytes express Fas, and LPMCs express FasL. The abolishment of enterocyte apoptosis observed in the presence of ZB4 antibody suggests that enterocytes are potential targets of lymphocyte infiltrate. These results directly demonstrate that FasL-mediated apoptosis is a major mechanism responsible for enterocyte death in CD.

Nonceliac gluten sensitivity: Sense or sensibility?

Recent studies support the existence of a new condition, nonceliac gluten sensitivity, which manifests as intestinal or extraintestinal symptoms that improve or disappear after gluten withdrawal in individuals with normal small-bowel mucosa and negative results on serum antitransglutaminase and antiendomysial antibody testing. Although the clinical value of this concept is under debate, the prevalence of nonceliac gluten sensitivity in the general population is supposed to be many times higher than that of celiac disease. The lack of an unambiguous definition of nonceliac gluten sensitivity, a major pitfall, is primarily related to the heterogeneous cause of this condition, whose symptoms are presumed to be caused by different mechanisms. If nonceliac gluten sensitivity is an etiologically heterogeneous syndrome, then management options should vary according to the predominant or concomitant underlying pathogenic pathways.

Matrix metalloproteinase pattern in celiac duodenal mucosa.

Matrix metalloproteinases (MMPs) are a family of endopeptidases playing a key role in tissue remodelling in both physiological and pathological conditions. Since little information is available about their role in celiac disease (CD), our aims were to quantify their expression/activity and to investigate their relation to proinflammatory cytokines in this condition. Duodenal biopsies from untreated, treated celiac patients and controls were used to quantify the expression of MMP-1, MMP-2, MMP-3, MMP-9, MMP-12, MMP-14, their inhibitor TIMP-1, IFN-γ and TNF-α by using real-time reverse transcription-polymerase chain reaction and the gelatin/casein/elastin activities by gel zymography, and to isolate lamina propria mononuclear cells (LPMCs). These cells and myofibroblasts isolated from jejunal specimens were incubated in the absence or presence of IFN-γ and TNF-α. MMP-1 and MMP-12 mRNA levels were significantly increased in active CD compared to treated (P<0.01 and P<0.0005, respectively) and normal mucosa (P<0.01 and P<0.0005, respectively), and this was paralleled by an upregulation of caseinolytic and elastolytic activities. Furthermore, MMP-12 levels significantly (P<0.05) correlated with those of IFN-γ and the degree of villous flattening. MMP-2 turned out to be significantly (P<0.05) reduced in untreated and treated celiacs compared to controls. In active CD, transcripts of TIMP-1 were higher than in treated and controls (P<0.005 and P<0.05, respectively), such as those of IFN-γ (P<0.05), whereas TNF-α levels were suppressed (P=0.0001). In physiological condition, myofibroblasts represent the main source of MMP-2, whereas LPMCs produce almost all MMPs only after cytokine stimulation. Conversely, cells isolated from active patients constitutively express MMPs without any increase after cytokine stimulation, while those from treated patients are in a resting condition. In conclusion, our results show the presence of a peculiar MMP pattern in active CD strongly dominated by MMP-12, correlating either with IFN-γ or the degree of mucosal damage.

Altered expression, localization, and phosphorylation of epithelial junctional proteins in celiac disease

We aimed to study the expression and localization of the molecular components of enterocyte junctions in celiac disease together with the level of tyrosine phosphorylation, a phenomenon known to affect their cellular distribution and function, and to explore the influence of proinflammatory cytokines. Duodenal biopsy specimens from patients with celiac disease and control subjects were used for immunoprecipitation, immunoblotting, and immunolocalization by using antioccludin, anti-zonula occludens (ZO)-1, anti-E-cadherin, anti-beta-catenin, and antiphosphotyrosine antibodies. The same procedures were carried out on filter-grown Caco-2 cells incubated in the absence or presence of interferon g and tumor necrosis factor a. In active celiac disease, the absence of a phosphorylated ZO-1 and the extensive phosphorylation of beta-catenin might be responsible for the absence of membranous localization of occludin and E-cadherin, respectively. The in vitro system showed an influence of the cytokines on the assembly of these complexes that proved the opposite to celiac samples as far as tight junctions were concerned because the presence of a phosphorylated ZO-1 enables occludin to localize in the membrane.