Luigina De Leo

The active Zot domain (aa 288–293) increases ZO-1 and myosin 1C serine/threonine phosphorylation, alters interaction between ZO-1 and its binding partners, and induces tight junction disassembly through proteinase activated receptor 2 activation

Vibrio cholerae‐derived zonula occludins toxin (Zot) is a multifunctional protein that reversibly disassembles intestinal tight junctions (tjs). Zot structure‐function analysis has mapped this activity to aa 288–293, named AT1002. AT1002 reduced transepithelial electrical resistance across rat small intestine, ex vivo, as did Zot and its processed mature form, ΔG. AT1002 increased in vivo permeability to sugar tracers, whereas scrambled control peptides did not. Binding and barrier assays in proteinase activated receptor (PAR)2‐expressing and PAR2‐null cells established AT1002 activity to be PAR2 dependent. Coincident with the increased intestinal permeability, confocal microscopy of AT1002‐exposed rat intestinal IEC6 cells revealed displacement of ZO‐1 and occludin from intercellular boundaries. In coimmunoprecipitation assays, AT1002 decreased ZO‐1‐occludin and ZO‐1‐claudin 1 interactions coincident with PKCα‐dependent ZO‐1 serine/threonine phosphorylation. Further, AT1002 increased serine phosphorylation of myosin 1C and, at the same time, transiently diminished its association with ZO‐1. The COOH‐terminal domain of ZO‐1 was required for its association with myosin 1C. These data indicate that the NH2‐terminal portion of active Zot contains a PAR2‐activating motif, FCIGRL, that increases PKCα‐dependent ZO‐1 and myosin 1C serine/threonine phosphorylation. These modifications provoke selective disengagement of ZO‐1 from its binding partners, occludin, claudin 1, and myosin 1C, coincident with opening of tjs.—Goldblum, S. E., Rai, U., Tripathi, A., Thakar, M., De Leo, L., Di Toro, N., Not, T., Ramachandran, R., Puche, A. C., Hollenberg, M. D., Fasano, A. The active Zot domain (aa 288–293) increases ZO‐1 and myosin 1C serine/ threonine phosphorylation, alters interaction between ZO‐1 and its binding partners, and induces tight junction disassembly through proteinase activated receptor 2 activation. FASEB J. 25, 144–158 (2011). www.fasebj.org

Natural isoprenoids are able to reduce inflammation in a mouse model of mevalonate kinase deficiency

Mevalonate kinase deficiency (MKD) is a rare disorder characterized by recurrent inflammatory episodes and, in most severe cases, by psychomotor delay. Defective synthesis of isoprenoids has been associated with the inflammatory phenotype in these patients, but the molecular mechanisms involved are still poorly understood, and, so far, no specific therapy is available for this disorder. Drugs like aminobisphosphonates, which inhibit the mevalonate pathway causing a relative defect in isoprenoids synthesis, have been also associated to an inflammatory phenotype. Recent data asserted that cell inflammation could be reversed by the addition of some isoprenoids, such as geranylgeraniol and farnesyl pyrophosphate. In this study, a mouse model for typical MKD inflammatory episode was obtained treating BALB/c mice with aminobisphosphonate alendronate and bacterial muramyldipeptide. The effect of exogenous isoprenoids—geraniol, farnesol, and geranylgeraniol—was therefore evaluated in this model. All these compounds were effective in preventing the inflammation induced by alendronate-muramyldipeptide, suggesting a possible role for these compounds in the treatment of MKD in humans.

A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles

We report here the design of a novel immunosensor and its application for celiac disease diagnosis, based on an electrogenerated chemiluminescence (ECL) readout, using membrane-templated gold nanoelectrode ensembles (NEEs) as a detection platform. An original sensing strategy is presented by segregating spatially the initial electrochemical reaction and the location of the immobilized biomolecules where ECL is finally emitted. The recognition scaffold is the following: tissue transglutaminase (tTG) is immobilized as a capturing agent on the polycarbonate (PC) surface of the track-etched templating membrane. It captures the target tissue transglutaminase antibody (anti-tTG), and finally allows the immobilization of a streptavidin-modified ruthenium-based ECL label via reaction with a suitable biotinylated secondary antibody. The application of an oxidizing potential in a tri-n-propylamine (TPrA) solution generates an intense and sharp ECL signal, suitable for analytical purposes. Voltammetric and ECL analyses evidenced that the ruthenium complex is not oxidized directly at the surface of the nanoelectrodes; instead ECL is generated following the TPrA oxidation, which produces the TPrA•+ and TPrA• radicals. With NEEs operating under total overlap diffusion conditions, high local fluxes of these reactive radicals are produced by the nanoelectrodes in the immediate vicinity of the ECL labels, so that they efficiently generate the ECL signal. The radicals can diffuse over short distances and react with the Ru(bpy)32+ label. In addition, the ECL emission is obtained by applying a potential of 0.88 V versus Ag/AgCl, which is about 0.3 V lower than when ECL is initiated by the electrochemical oxidation of Ru(bpy)3(2+). The immunosensor provides ECL signals which scale with anti-tTG concentration with a linearity range between 1.5 ng·mL–1 and 10 μg·mL–1 and a detection limit of 0.5 ng·mL–1. The sensor is finally applied to the analysis of anti-tTG in human serum samples, showing to be suitable to discriminate between healthy and celiac patients.

Targeting farnesyl-transferase as a novel therapeutic strategy for mevalonate kinase deficiency: in vitro and in vivo approaches.

Mevalonate kinase deficiency (MKD) is a rare inborn auto-inflammatory disease due to the impairment of the pathway for the biosynthesis of cholesterol and non-sterol isoprenoids. The shortage of isoprenoids compounds and in particular of geranylgeranylpyrophosphate (GGPP) was recently associated to the MKD characteristic inflammatory attacks. The aim of this study is to demonstrate that the normalization of the mevalonate pathway intermediates levels and in particular of GGPP, through the specific inhibition of farnesyl-transferase (FT) with Manumycin A could ameliorate the inflammatory phenotype of MKD patients. The effect of Manumycin A was first evaluated in MKD mouse and cellular models, chemically obtained using the aminobisphosphonate alendronate (ALD), and then in monocytes isolated from 2 MKD patients. Our findings were compared to those obtained by using natural exogenous isoprenoids (NEIs). Manumycin A was able to significantly reduce the inflammatory marker serum amyloid A in ALD-treated Balb/c mice, as well as IL-1 beta secretion in ALD-monocytes and in MKD patients. These results clearly showed that, through the inhibition of FT, an increased number of mevalonate pathway intermediates could be redirected towards the synthesis of GGPP diminishing the inflammatory response. The importance in limiting the shortage of GGPP was emphasized by the anti-inflammatory effect of NEIs that, due to their biochemical structure, can enter the MKD pathway. In conclusion, manumycin A, as well as NEIs, showed anti-inflammatory effect in MKD models and especially in MKD-monocytes, suggesting novel approaches in the treatment of MKD, an orphan disease without any efficacious treatment currently available.

Serum Anti-Tissue Transglutaminase Antibodies Detected during Febrile Illness May Not Be Produced by the Intestinal Mucosa

Anti-transglutaminase antibodies are the diagnostic marker of celiac disease, and are considered to be synthesized only by intestinal B-lymphocytes. During an infectious disease, these antibodies are transiently detected in serum. We show that these infection-triggered antibodies may not originate in the intestinal mucosa and are not an indication of celiac disease.

Innate and adaptive immunity in self-reported nonceliac gluten sensitivity versus celiac disease

BACKGROUND Immune mechanisms have been implicated in nonceliac gluten sensitivity (NCGS), a condition characterized by intestinal and/or extraintestinal symptoms caused by the ingestion of gluten in non-celiac/non-wheat allergic individuals. AIMS We investigated innate and adaptive immunity in self-reported NCGS versus celiac disease (CD). METHODS In the supernatants of ex vivo-cultured duodenal biopsies from 14 self-reported NCGS patients, 9 untreated and 10 treated CD patients, and 12 controls we detected innate cytokines - interleukin (IL)-15, tumor necrosis factor-α, IL-1β, IL-6, IL-12p70, IL-23, IL-27, IL-32α, thymic stromal lymphopoietin (TSLP), IFN-α-, adaptive cytokines - interferon (IFN)-γ, IL-17A, IL-4, IL-5, IL-10, IL-13-, chemokines - IL-8, CCL1, CCL2, CCL3, CCL4, CCL5, CXCL1, CXCL10-, granulocyte colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF). RESULTS Mucosal innate and adaptive cytokines, chemokines and growth factors did not differ between self-reported NCGS, treated CD and controls. On the contrary, IL-6, IL-15, IL-27, IFN-α, IFN-γ, IL-17A, IL-23, G-CSF, GM-CSF, IL-8, CCL1 and CCL4 were significantly higher in untreated CD than in self-reported NCGS, treated CD and controls, while TSLP was significantly lower in untreated CD than in self-reported NCGS, treated CD and controls. CONCLUSION In our hands, patients with self-reported NCGS showed no abnormalities of the mucosal immune response.

Fasting Increases Tobramycin Oral Absorption in Mice

ABSTRACT The pharmacokinetics of the aminoglycoside tobramycin was evaluated after oral administration to fed or fasting (15 h) mice. As expected, under normal feeding conditions, oral absorption was negligible; however, fasting induced a dramatic increase in tobramycin bioavailability. The dual-sugar test with lactulose and l-rhamnose confirmed increased small bowel permeability via the paracellular route in fasting animals. When experiments aimed at increasing the oral bioavailability of hydrophilic compounds are performed, timing of fasting should be extremely accurate.

Anti-transglutaminase 6 autoantibody development in children with celiac disease correlates with duration of gluten exposure

Objectives: Antibodies against transglutaminase 6 (anti-TG6) have been implicated in neurological manifestations in adult patients with genetic gluten intolerance, and it is unclear whether autoimmunity to TG6 develops following prolonged gluten exposure. We measured the anti-TG6 in children with celiac disease (CD) at the diagnosis time to establish a correlation between these autoantibodies and the duration of gluten exposure. We investigated a correlation between anti-TG6 and the presence of neurological disorders. Methods: Anti-TG6 (IgA/IgG) were measured by ELISA in sera of children with biopsy-proven CD and of children experiencing gastrointestinal disorders. CD patients positive for anti-TG6 were retested after 2 years of gluten-free diet (GFD). Results: We analyzed the sera of 274 CD children and of 121 controls. Anti-TG6 were detected in 68/274 (25%) CD patients and in 19/121 (16%) controls, with significant difference between the 2 groups (P = 0.04). None of the CD patients and of the controls testing positive for anti-TG6 were experiencing neurological disorders. Eleven of 18 (61%) CD patients with other autoimmune diseases were positive for anti-TG6. In CD patients, a significant correlation between the gluten exposure before the CD diagnosis and anti-TG6 concentration was found (P = 0.006 for IgA; P < 0.0001 for IgG). After GFD anti-TG6 concentrations were significantly reduced (P < 0.001). No significant correlation was observed between anti-TG6 and anti-TG2 serum concentrations. Conclusions: Anti-TG6 are more prevalent in children with untreated CD in the absence of overt neurological disorders. The synthesis of the anti-TG6 is related to a longer exposure to gluten before the CD diagnosis, and the autoimmunity against TG6 is gluten dependent and disappeared during GFD.

Cross-sectional study of coeliac autoimmunity in a population of Vietnamese children

Objective The prevalence of coeliac disease (CD) in Vietnam is unknown. To fill this void, we assessed the prevalence of serological markers of CD autoimmunity in a population of children in Hanoi. Setting The outpatient blood drawing laboratory of the largest paediatric hospital in North Vietnam was used for the study, which was part of an international project of collaboration between Italy and Vietnam. Participants Children having blood drawn for any reason were included. Exclusion criteria were age younger than 2 years, acquired or congenital immune deficiency and inadequate sample. A total of 1961 children (96%) were enrolled (838 females, 1123 males, median age 5.3 years). Outcomes Primary outcome was the prevalence of positive autoimmunity to both IgA antitransglutaminase antibodies (anti-tTG) assessed with an ELISA test and antiendomysial antibodies (EMA). Secondary outcome was the prevalence of CD predisposing human leucocyte antigens (HLA) (HLA DQ2/8) in the positive children and in a random group of samples negative for IgA anti-tTG. Results The IgA anti-tTG test was positive in 21/1961 (1%; 95% CI 0.61% to 1.53%); however, EMA antibodies were negative in all. HLA DQ2/8 was present in 7/21 (33%; 95% CI 14.5% to 56.9%) of the anti-tTG-positive children and in 72/275 (26%; 95% CI 21% to 32%) of those who were negative. Conclusions Coeliac autoimmunity is rare in Vietnam, although prevalence of HLA DQ2/8 is similar to that of other countries. We hypothesise that the scarce exposure to gluten could be responsible for these findings.

Intestinal-mucosa anti-transglutaminase antibody assays to test for genetic gluten intolerance.

Intestinal-mucosa anti-transglutaminase antibody assays to test for genetic gluten intolerance