The involvement of IgH enhancer HS1.2 in the pathogenesis of Crohn's disease: how the immune system can influence a multifactorial disease.

OBJECTIVE: To study the 3' immunoglobulin heavy-chain regulatory region (3'RR) enhancer complex, active in class switching recombination and in B-cells, in Crohn's disease. PATIENTS AND METHODS: A total of 167 patients [79 females (47.3%) and 88 males (52.7%)] affected by Crohn's disease were enrolled in the study. As a control, we included 64 healthy subjects, age and sex matched, from the same geographical area. Blood tests were performed on all subjects to determine their antibody levels and to detect the presence of any possible infections. We conducted a selective PCR, which amplified the hs1.2-A region. The nested second PCR to amplify the polymorphic core of the enhancer was performed. RESULTS: No differences between cases and controls were observed with respect to sex distribution (43.8% females among controls and 49.5% among cases), age, tTG IgA, RF, serum or secretory IgA, IgG1, IgG2 and IgG3. No correlation was found between both seric and secretory immunoglobulins levels, with except of statistically significant differences between cases and controls with respect to IgA and IgG ASCA positivity (p<0.001), serum IgG4 (p<0.001) and IgD (p=0.001). CONCLUSIONS: We have demonstrated that in Crohn's disease, the HS1,2 immunoglobulins enhancer is not implicated in the disease pathogenesis. Moreover, we have found that IgG4 levels are lower in Crohn's disease patients than in controls; these data may be related to an impairment of number and function of Tregs, further linked to the presence of tissue inflammation. Crohn's disease is a complex multifactorial disease. The pathogenesis of Crohn's disease is incompletely understood although it is clear that the disease involves multiple interacting agents.

Central and Mucosal Immunities are Modified by Non Adsorbable Antibiotic Treatment in Uncomplicated Diverticular Disease.

We review our experience on Rifaximin in uncomplicated diverticular disease. Our data show that a 2 week treatment induces modifications in the immune system: local mucosal lymphocytes with TLR-4 were increased. In the peripheral blood CD103 cells, which increased before treatment, returned to normal values after Rifaximin.

The Interaction among Microbiota, Immunity, and Genetic and Dietary Factors Is the Condicio Sine Qua Non Celiac Disease Can Develop.

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. This is a complex disorder involving both environmental and immune-genetic factors. The major genetic risk factor for CD is determined by HLA-DQ genes. Dysfunction of the innate and adaptive immune systems can conceivably cause impairment of mucosal barrier function and development of localized or systemic inflammatory and autoimmune processes. Exposure to gluten is the main environmental trigger responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Thus, both genetic determination and environmental exposure to gluten are necessary for the full manifestation of CD; neither of them is sufficient alone. Epidemiological and clinical data suggest that other environmental factors, including infections, alterations in the intestinal microbiota composition, and early feeding practices, might also play a role in disease development. Thus, this interaction is the condicio sine qua non celiac disease can develop. The breakdown of the interaction among microbiota, innate immunity, and genetic and dietary factors leads to disruption of homeostasis and inflammation; and tissue damage occurs. Focusing attention on this interaction and its breakdown may allow a better understanding of the CD pathogenesis and lead to novel translational avenues for preventing and treating this widespread disease.

Common variable immunodeficiency - new insight into the pathogenesis and the quest for a workable classification.

In this editorial we argue that more and more complex classifications for patients with common variable immunodeficiency (CVID) fail to identify those patients at high risk of developing infections. We propose that the minimal requirement to identify such patients is the absolute numbers of total and memory B cells and the IgM response to immunization with polysaccharides. If these data should be confirmed, they will provide the basis for a good classification of a heterogeneous group of patients. This simple, workable classification may result in a clinically useful identification of patients prone to more aggressive infections.

New insights on the role of T cells in the pathogenesis of celiac disease.

Despite intense investigation, the pathogenetic mechanisms leading to villous atrophy in Celiac disease (CD) remain not completely understood. The traditional interpretation is that CD4 cells recognize gliadin and develop an inflammatory reaction by production of Th1 cytokines at the mucosa level inducing CD8 cells to kill mucosal cells by a direct cytotoxic mechanism or by Fas-mediated apoptosis. Recent data, however, have shown that novel CD4 T-cells subpopulations, CD4+ CD25+ Regulatory T cells (Tregs) and Th17 cells also play a role in the ongoing inflammatory process. Both Tregs and Th17 cells are increased in active CD. However, because Tregs have a suppressive activity on inflammation, their role is controversial. In this editorial we discuss these recent findings and the hypothesis formulated to explain the increase of Tregs. To understand the pathogenesis of tissue damage of CD, we have focused on the duodenal micro-environment, introducing the new concept of immunological niche that in CD summarizes cellular and cytokine interactions in duodenal mucosa, where a high plasticity of T-cell subsets is present. CD is often complicated by T-cell lymphomas, especially in cases of refractory CD.

Selectivity of protein carbonylation in the apoptotic response to oxidative stress associated with photodynamic therapy: a cell biochemical and proteomic investigation.

We previously reported that photodynamic therapy (PDT) using Purpurin-18 (Pu-18) induces apoptosis in HL60 cells. Using flow cytometry, two-dimensional electrophoresis coupled with immunodetection of carbonylated proteins and mass spectrometry, we now show that PDT-induced apoptosis is associated with increased reactive oxygen species generation, glutathione depletion, changes in mitochondrial transmembrane potential, simultaneous downregulation of mitofilin and carbonylation of specific proteins: glucose-regulated protein-78, heat-shock protein 60, heat-shock protein cognate 71, phosphate disulphide isomerase, calreticulin, beta-actin, tubulin-alpha-1-chain and enolase-alpha. Interestingly, all carbonylated proteins except calreticulin and enolase-alpha showed a pI shift in the proteome maps. Our results suggest that PDT with Pu-18 perturbs the normal redox balance and shifts HL60 cells into a state of oxidative stress, which systematically induces the carbonylation of specific chaperones. As these proteins normally produce a prosurvival signal during oxidative stress, we hypothesize that their carbonylation represents a signalling mechanism for apoptosis induced by PDT.

Thiolation and nitrosation of cysteines in biological fluids and cells.

Thiols (RSH) are potent nucleophilic agents, the rates of which depend on the pKa of the sulfhydryl. Unlike compounds having other nucleophile moieties (-OH or -NH(2)), RSH are involved in reactions, such as conjugations, redox and exchange reactions. Although protein SH groups (PSH) react like non-protein thiols (NPSH), the biochemistry of proteins is much more complex for reasons such as steric hindrance, charge distribution and accessibility of PSH to the solvent (protein conformation). The reaction rates and types of end-products of PSH vary a lot from protein to protein. The biological problem is even more complex because in all compartments and tissues, there may be specific competition between thiols (namely between GSH and PSH), regulated by the properties of antioxidant enzymes. Moreover, PSH are divided biologically into essential and non-essential and their respective influence in the various biological systems is unknown. It follows that during phenomena eliciting a prompt thiol response (oxidative stress), the antioxidant PSH response and reaction mechanisms vary considerably from case to case. For example, in spite of a relatively low pKa that should guarantee good antioxidant capacity, PSH of albumin has much less propensity to form adducts with conjugating agents than NPSH; moreover, the structural characteristics of the protein prevent albumin from forming protein disulfides when exposed to oxidants (whereas protein-thiol mixed disulfides are formed in relative abundance). On the other hand, proteins with a relatively high reactivity, such rat hemoglobin, have much greater antioxidant capacity than GSH, but although human hemoglobin has a pKa similar to GSH, for structural reasons it has less antioxidant capacity than GSH. When essential PSH are involved in S-thiolation and S-nitrosation reactions, a similar change in biological activity is observed. S-thiolated proteins are a recurrent phenomenon in oxidative stress elicited by reactive oxygen species (ROS). This event may be mediated by disulfides, that exchange with PSH, or by the protein intermediate sulfenic acid that reacts with thiols to form protein-mixed disulfides. During nitrosative stress elicited by reactive nitrogen species (RNS), depending on the oxygen concentration of the system, nitrosation reactions of thiols may also be accompanied by protein S-thiolation. In this review we discuss a number of cell processes and biochemical modifications of enzymes that indicate that S-thiolation and S-nitrosation may occur simultaneously in the same protein in the presence of appropriate interactions between ROS and RNS.