Nutrition of the critically ill - emphasis on liver and pancreas

About 25 million individuals undergo high risk surgery each year. Of these about 3 million will never return home from hospital, and the quality of life for many of those who return is often significantly impaired. Furthermore, many of those who manage to leave hospital have undergone severe life-threatening complications, mostly infections/sepsis. The development is strongly associated with the level of systemic inflammation in the body, which again is entirely a result of malfunctioning GI microbiota, a condition called dysbiosis, with deranged composition and function of the gastrointestinal microbiota from the mouth to the anus and impaired ability to maintain intact mucosal membrane functions and prevent leakage of toxins-bacterial endotoxins and whole or debris of bacteria, but also foods containing proteotoxins gluten, casein and zein and heat-induced molecules such as advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs). Markedly lower total anaerobic bacterial counts, particularly of the beneficial Bifidobacterium and Lactobacillus and higher counts of total facultative anaerobes such as Staphylococcus and Pseudomonas are often observed when analyzing the colonic microbiota. In addition Gram-negative facultative anaerobes are commonly identified microbial organisms in mesenteric lymph nodes and at serosal "scrapings" at laparotomy in patients suffering what is called "Systemic inflammation response system" (SIRS). Clearly the outcome is influenced by preexisting conditions in those undergoing surgery, but not to the extent as one could expect. Several studies have for example been unable to find significant influence of pre-existing obesity. The outcome seems much more to be related to the life-style of the individual and her/his "maintenance" of the microbiota e.g., size and diversity of microbiota, normal microbiota, eubiosis, being highly preventive. About 75% of the food Westerners consume does not benefit microbiota in the lower gut. Most of it, refined carbohydrates, is already absorbed in the upper part of the GI tract, and of what reaches the large intestine is of limited value containing less minerals, less vitamins and other nutrients important for maintenance of the microbiota. The consequence is that the microbiota of modern man has a much reduced size and diversity in comparison to what our Palelithic forefathers had, and individuals living a rural life have today. It is the artificial treatment provided by modern care, unfortunately often the only alternative, which belongs to the main contributor to poor outcome, among them; artificial ventilation, artificial nutrition, hygienic measures, use of skin penetrating devices, tubes and catheters, frequent use of pharmaceuticals, all known to significantly impair the total microbiome of the body and dramatically contribute to poor outcome. Attempts to reconstitute a normal microbiome have often failed as they have always been undertaken as a complement to and not an alternative to existing treatment schemes, especially treatments with antibiotics. Modern nutrition formulas are clearly too artificial as they are based on mixture of a variety of chemicals, which alone or together induce inflammation. Alternative formulas, based on regular food ingredients, especially rich in raw fresh greens, vegetables and fruits and with them healthy bacteria are suggested to be developed and tried.

Association of HLA-DQ gene with bowel transit, barrier function, and inflammation in irritable bowel syndrome with diarrhea

Patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D) carrying human leukocyte antigen (HLA)-DQ2/8 genotypes benefit from gluten withdrawal. Our objective was to compare gastrointestinal barrier function, mucosal inflammation, and transit in nonceliac IBS-D patients and assess association with HLA-DQ2/8 status. In 45 IBS-D patients who were naive to prior exclusion of dietary gluten, we measured small bowel (SB) and colonic mucosal permeability by cumulative urinary lactulose and mannitol excretion (0-2 h for SB and 8-24 h for colon), inflammation on duodenal and rectosigmoid mucosal biopsies (obtained in 28 of 45 patients), tight junction (TJ) protein mRNA and protein expression in SB and rectosigmoid mucosa, and gastrointestinal and colonic transit by validated scintigraphy. SB mucosal biopsies were stained with hematoxylin-eosin to assess villi and intraepithelial lymphocytes, and immunohistochemistry was used to assess CD3, CD8, tryptase, and zonula occludens 1 (ZO-1); colonic biopsy intraepithelial lymphocytes were quantitated. Associations of HLA-DQ were assessed using Wilcoxon's rank-sum test. Relative to healthy control data, we observed a significant increase in SB permeability (P < 0.001), a borderline increase in colonic permeability (P = 0.10), and a decrease in TJ mRNA expression in rectosigmoid mucosa in IBS-D. In HLA-DQ2/8-positive patients, ZO-1 protein expression in the rectosigmoid mucosa was reduced compared with that in HLA-DQ2/8-negative patients and colonic transit was slower than in HLA-DQ2/8-negative patients. No other associations with HLA genotype were identified. There is abnormal barrier function (increased SB permeability and reduced mRNA expression of TJ proteins) in IBS-D relative to health that may be, in part, related to immunogenotype, given reduced ZO-1 protein expression in rectosigmoid mucosa in HLA-DQ2/8-positive relative to HLA-DQ2/8-negative patients.

In depth analysis of risk factors for coeliac disease amongst children under 18 years old in the Gaza strip. A cross sectional study

Coeliac disease is an important clinical disorder affecting the human gastrointestinal tract leading to multiple signs and symptoms in different body organs. This disease was the subject of a cross sectional descriptive-analytic study conducted in the Gaza Strip during 2010. Objectives were oriented to identify and verify several variables and attributes affecting the prognosis of coeliac disease in the patients. Ninety five children out of 113 patients were arranged into two groups according to age from 2 to 11 years and from 12 to 18 years old. Results showed the poor interest of health professionals regarding coeliac disease in the Gaza Strip. The mean age of study population was 5.47 years for males and 8.93 years for females. The lifestyle of coeliac patients was directly proportional with better nutritional indictors. Poor recognition of the emblem illustrating gluten in foods implicates effective health awareness or promotion. The more knowledgeable patients or mothers (P = 0.036) were the more compliant. The compliance to giving gluten free foods outside home was statistically significant (P = 0.037). Similarly, cautious approach when buying foods or detergents (P = 0.011). According to BMI 74.4%, 23.4% and 3.2% of all patients were normal, underweight and overweight respectively. Albumin blood level was normal in 32.6% and low in 67.4%. Meanwhile, blood calcium level was normal in 76.8%, low in 21.1% and high in 2.1% of all patients.

CONCLUSION

The study showed that recreation and social activities for coeliac patients are substantially missing in the Gaza Strip. Moreover, the study proved that AEI is a reliable centre for care of coeliac disease patients and conducting relevant studies.

RECOMMENDATION

There is a need for thorough and continuous community and institutional mobilization regarding coeliac disease in the Gaza Strip and in Palestine.

Pathophysiology of celiac disease

Celiac disease results from the interplay of genetic, environmental, and immunologic factors. An understanding of the pathophysiology of celiac disease, in which the trigger (wheat, rye, and barley) is known, will undoubtedly reveal basic mechanisms that underlie other autoimmune diseases (eg, type 1 diabetes) that share many common pathogenic perturbations. This review describes seminal findings in each of the 3 domains of the pathogenesis of celiac disease, namely genetics, environmental triggers, and immune dysregulation, with a focus on newer areas of investigation such as non-HLA genetic variants, the intestinal microbiome, and the role of the innate immune system.

Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) and nonallergic food intolerance: FODMAPs or food chemicals?

Food intolerance in irritable bowel syndrome (IBS) is increasingly being recognized, with patients convinced that diet plays a role in symptom induction. Evidence is building to implicate fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) in the onset of abdominal pain, bloating, wind and altered bowel habit through their fermentation and osmotic effects. Hypersensitivity to normal levels of luminal distension is known to occur in patients with IBS, with consideration of food chemical intolerance likely to answer many questions about this physiological process. This paper summarizes the evidence and application of the most common approaches to managing food intolerance in IBS: the low-FODMAP diet, the elimination diet for food chemical sensitivity and others including possible noncoeliac gluten intolerance.

Nomenclature and listing of celiac disease relevant gluten T-cell epitopes restricted by HLA-DQ molecules

Celiac disease is caused by an abnormal intestinal T-cell response to gluten proteins of wheat, barley and rye. Over the last few years, a number of gluten T-cell epitopes restricted by celiac disease associated HLA-DQ molecules have been characterized. In this work, we give an overview of these epitopes and suggest a comprehensive, new nomenclature.

Review article: coeliac disease, new approaches to therapy

BACKGROUND

Coeliac disease is managed by life-long gluten withdrawal from the diet. However, strict adherence to a gluten-free diet is difficult and is not always effective. Novel therapeutic approaches are needed to supplement or even replace the dietary treatment.

AIM

To review recent advances in new therapeutic options for coeliac disease.

METHODS

A literature search was performed on MEDLINE, EMBASE, Web of Science, Scopus, DDW.org and ClinicalTrials.gov for English articles and abstracts. The search terms used included, but not limited to, 'Celiac disease', 'new', 'novel', 'Advances', 'alternatives' and 'Drug therapy'. The cited articles were selected based on the relevancy to the review objective.

RESULTS

Several new therapeutic approaches for coeliac disease are currently under development by targeting its underlying pathogenesis. Alternative therapies range from reproduction of harmless wheat strains to immunomodulatory approaches. Some of these therapies such as enzymatic cleavage of gluten and permeability inhibitors have shown promise in clinical studies.

CONCLUSIONS

Gluten-free diet is still the only practical treatment for patients with coeliac disease. Novel strategies provide promise of alternative adjunctive approaches to diet restriction alone for patients with this disorder.

Neurologic and psychiatric manifestations of celiac disease and gluten sensitivity

Celiac Disease (CD) is an immune-mediated disease dependent on gluten (a protein present in wheat, rye or barley) that occurs in about 1% of the population and is generally characterized by gastrointestinal complaints. More recently the understanding and knowledge of gluten sensitivity (GS), has emerged as an illness distinct from celiac disease with an estimated prevalence 6 times that of CD. Gluten sensitive people do not have villous atrophy or antibodies that are present in celiac disease, but rather they can test positive for antibodies to gliadin. Both CD and GS may present with a variety of neurologic and psychiatric co-morbidities, however, extraintestinal symptoms may be the prime presentation in those with GS. However, gluten sensitivity remains undertreated and underrecognized as a contributing factor to psychiatric and neurologic manifestations. This review focuses on neurologic and psychiatric manifestations implicated with gluten sensitivity, reviews the emergence of gluten sensitivity distinct from celiac disease, and summarizes the potential mechanisms related to this immune reaction.

New insights in celiac disease

Celiac disease (CD) is an autoimmune disorder occurring in genetically susceptible subjects. The incidence of CD is around 1%, and it is much more common in first-degree relatives of CD patients, 10%-18%. However, the pattern of the genetic inheritance is still obscure. Environmental factors are undoubtedly affecting the disease's clinical presentation, time at presentation, and may have an effect on the characteristics of the disease. The clinical presentation of CD has shifted during the previous decades from the classical presentation in which the toddler suffers from diarrhea, constipation, vomiting, failure to thrive, abdominal distension, etc., to the child with a monosymptomatic presentation, such as anemia, as well as an enlarged list of extra-intestinal disorders. The diagnosis of CD is being established by symptoms consistent with CD and positive serology. The ultimate diagnosis should be made upon histological evaluation of the small bowel mucosa. The treatment of CD is a lifelong, strict gluten-free diet (GFD). Compliance with a GFD is quite difficult. Therefore, new strategies for prevention and treatment modalities other than GFD are greatly needed. Recently several promising therapeutic modalities have been developed; these include resuming traditional baking techniques. Another methodology is using probiotic-driven prolylendopeptidase. Another pathway to tackle the therapeutic option in CD is by down-regulation of the activity of zonulin-the active pump enabling gluten to enter the enterocytes. We are facing an era where other modalities beyond a GFD might allow CD patients to be able to tolerate occasionally a small amount of gluten in their diet.

Serologic markers of gluten sensitivity in a healthy population from the western region of Saudi Arabia

BACKGROUND/AIM

To identify the prevalence of gluten sensitivity in a healthy adult Saudi population within a low endemic area of celiac disease using IgA tissue transglutaminase antibody. The study was conducted as a prospective pilot study for Saudi attendees of a blood donation centre at King Faisal Specialist Hospital & Research Centre in Jeddah, Saudi Arabia.

PATIENTS AND METHODS

Individuals were invited to participate in the study and screened for gluten sensitivity using immunoglobulin A tissue transglutaminase antibody (IgA TTG) along with serum IgA level. Descriptive data was presented and expressed as mean value; correlation between variables was estimated using Pearson correlation, and nonparametric data using Pearson rho correlation (level of P value <0.05 is considered to be statistically significant).

RESULTS

Two hundred and four individuals (122 males and 82 females, mean age 35 years) attending the blood donation centre were screened. Three individuals tested positive for IgA TTG showing normal IgA level (1 female and 2 males) with a 1.5% prevalence in the cohort.

CONCLUSIONS

Positive celiac screening is present at a low prevalence rate in our adult population, in which the individuals' age and their serum IgA levels are not associated with the positivity level. A study on a larger scale with the application of histologic confirmation of positive cases is needed.

Update on celiac disease - etiology, differential diagnosis, drug targets, and management advances

Celiac disease (CD) is an immune-mediated enteropathy triggered by exposure to wheat gluten and similar proteins found in rye and barley that affects genetically susceptible persons. This immune-mediated enteropathy is characterized by villous atrophy, intraepithelial lymphocytosis, and crypt hyperplasia. Once thought a disease that largely presented with malnourished children, the wide spectrum of disease activity is now better recognized and this has resulted in a shift in the presenting symptoms of most patients with CD. New advances in testing, both serologic and endoscopic, have dramatically increased the detection and diagnosis of CD. While the gluten-free diet is still the only treatment for CD, recent investigations have explored alternative approaches, including the use of altered nonimmunogenic wheat variants, enzymatic degradation of gluten, tissue transglutaminase inhibitors, induction of tolerance, and peptides to restore integrity to intestinal tight junctions.

New and developing therapies for celiac disease

The treatment for celiac disease, a removal of gluten in the diet, is safe and effective for the vast majority of patients. There is a large body of evidence that the diagnosis and treatment of those with celiac disease ensures considerable health benefits. Although a gluten-free diet is the principal treatment for celiac disease, it is relatively expensive, inconvenient and difficult to adhere to. For these reasons, there is interest in developing alternative therapies. Emerging research for the treatment of celiac disease has focused on three areas: to decrease gluten exposure, to modify intestinal permeability and to modulate immune activation. Therapies developed thus far consist of enzymes designed to digest gluten and the use of inhibitors of paracellular permeability to decrease the migration of gluten peptides into the lamina propria. Other potential therapeutic maneuvers include the binding of gluten by polymers, the use of tissue transglutaminase (TTG) inhibitors and DQ2 or DQ8 blockers, or modulation of cytokine production. While all represent new and exciting therapies, an ideal therapy should have virtually no side effects similar to a gluten-free diet. A pharmaceutical agent may be used on an intermittent basis, such as following occasional gluten exposure or on a chronic basis to mitigate the effects of potential inadvertent ingestion of gluten.

Novel therapies for coeliac disease

Coeliac disease is a widespread, lifelong disorder for which dietary control represents the only accepted form of therapy. There is an unmet need for nondietary therapies to treat this condition. Most ongoing and emerging drug-discovery programmes are based on the understanding that coeliac disease is caused by an inappropriate T-cell-mediated immune response to dietary gluten proteins. Recent genome-wide association studies lend further support to this pathogenic model. The central role of human leucocyte antigen genes has been validated, and a number of new risk loci have been identified, most of which are related to the biology of T cells and antigen-presenting cells. Here, we review the status of potential nondietary therapies under consideration for coeliac disease. We conclude that future development of novel therapies will be aided considerably by the identification of new, preferably noninvasive, surrogate markers for coeliac disease activity.

Celiac autoimmunity in children with type 1 diabetes: a two-year follow-up

OBJECTIVE

To determine the benefits of screening for celiac autoimmunity via immunoglobulin A transglutaminase autoantibodies (TG) in children with type 1 diabetes (T1D).

STUDY DESIGN

We followed up 79 screening-identified TG+ and 56 matched TG- children with T1D for 2 years to evaluate growth, bone mineral density, nutritional status, and diabetes control. TG+ subjects self-selected to gluten-free or gluten-containing diet.

RESULTS

Of the initial cohort, 80% were available for reexamination after 2 years. TG+ subjects had consistently lower weight z-scores and higher urine N-telopeptides than TG- subjects, but similar measures of bone density and diabetes outcomes. TG+ children who remained on a gluten-containing diet had lower insulin-like growth factor binding protein 3 z-scores compared with TG+ subjects who reported following a gluten-free diet. Children who continued with high TG index throughout the study had lower bone mineral density z-scores, ferritin, and vitamin D 25OH levels, compared with the TG- group.

CONCLUSIONS

No significant adverse outcomes were identified in children with T1D with screening-identified TG+ who delay therapy with a gluten-free diet for 2 years. Children with persistently high levels of TG may be at greater risk. The optimal timing of screening and treatment for celiac disease in children with T1D requires further investigation.

Patients with celiac disease and B-cell lymphoma have a better prognosis than those with T-cell lymphoma

BACKGROUND & AIMS

Celiac disease (CD) is associated with an increased risk of lymphoma. However, relatively few studies have assessed the outcome of patients diagnosed with both CD and lymphoma. We evaluated the temporal association between lymphoma and CD, along with clinical presentation, response to therapy, and prognosis.

METHODS

Patients diagnosed with both CD and lymphoma were identified retrospectively in a tertiary referral center. Clinical characteristics and survival were analyzed.

RESULTS

Sixty-three patients (36 men) were identified who had been diagnosed with lymphoma and CD. Thirty-six (57%) were diagnosed with CD before they were diagnosed with lymphoma. The most common histologic entity was diffuse, large, B-cell lymphoma, which affected 18 (29%) patients. Complete information for staging was available in 59 patients; 24 (38%) had stage IV disease. Only chemotherapy or only radiation therapy was used for 43 (68%) and 11 (17%) patients, respectively. The 5- and 10-year cumulative survival rates for the entire cohort were 58% and 39%, respectively. Survival of patients with T-cell lymphoma was shorter than for all other lymphomas (119.4 vs 22.8 mo; P = .02).

CONCLUSIONS

CD is associated with B- and T-cell lymphomas. Patients with B-cell lymphomas had a better prognosis than those with T-cell lymphoma. Therapy is unsatisfactory for enteropathy-type T-cell lymphoma.

Infant and childhood diet and type 1 diabetes risk: recent advances and prospects

Type 1 diabetes is a chronic autoimmune disease characterized by a preclinical period of autoimmunity. It is well accepted that both genetic and environmental factors contribute to disease risk. Given that type 1 diabetes, and its preclinical autoimmunity, appear early in life, infant and childhood diet have been implicated as potential initiating exposures in the etiology of the disease. Several publications in the past year have provided further evidence for existing hypotheses regarding the roles of wheat, cow's milk, omega-3 fatty acids, and the maternal diet during pregnancy. However, inconsistencies in findings between studies suggest the need for collaboration and standardization of study methods to move forward in research in this area. One such example of this is the TEDDY (The Environmental Determinants of Diabetes in the Young) study, which is an international, multicenter birth cohort study with standardized recruitment, dietary collection methodologies, and analytic approaches.

Novel immune response to gluten in individuals with schizophrenia

A link between celiac disease and schizophrenia has been postulated for several years, based primarily on reports of elevated levels of antibody to gliadin in patients. We sought to examine the proposed connection between schizophrenia and celiac disease by characterizing the molecular specificity and mechanism of the anti-gliadin immune response in a subset of individuals with schizophrenia. Blood samples from individuals with schizophrenia and elevated anti-gliadin antibody titer were examined for celiac disease-associated biomarkers, including antibodies to transglutaminase 2 (TG2) enzyme and deamidated gliadin peptides, as well as the HLA-DQ2 and -DQ8 MHC genes. The anti-gliadin antibody response was further characterized through examination of reactivity towards chromatographically separated gluten proteins. Target proteins of interest were identified by peptide mass mapping. In contrast to celiac disease patients, an association between the anti-gliadin immune response and anti-TG2 antibody or HLA-DQ2 and -DQ8 markers was not found in individuals with schizophrenia. In addition, the majority of individuals with schizophrenia and anti-gliadin antibody did not exhibit antibody reactivity to deamidated gliadin peptides. Further characterization of the antibody specificity revealed preferential reactivity towards different gluten proteins in the schizophrenia and celiac disease groups. These findings indicate that the anti-gliadin immune response in schizophrenia has a different antigenic specificity from that in celiac disease and is independent of the action of transglutaminase enzyme and HLA-DQ2/DQ8. Meanwhile, the presence of elevated levels of antibodies to specific gluten proteins points to shared immunologic abnormalities in a subset of schizophrenia patients. Further characterization and understanding of the immune response to gluten in schizophrenia may provide novel insights into the etiopathogenesis of specific disease phenotypes.

Celiac disease

PURPOSE OF REVIEW

To summarize recent advances in celiac disease published between August 2008 and July 2009.

RECENT FINDINGS

Celiac disease affects nearly 1% of most populations but remains largely unrecognized. In the last year, work has shown that the prevalence of celiac disease has increased dramatically, not simply due to increased detection. Also, undiagnosed celiac disease may be associated with increased mortality. Significant progress has been made in understanding how gliadin peptides can cross the intestinal border and access the immune system. New genetic loci and candidate genes that may contribute to the risk of celiac disease and its overlap with type 1 diabetes mellitus have been identified. Novel deamidated gliadin peptides antibodies have better diagnostic accuracy over native gliadin-based tests. The inclusion of duodenal bulb biopsy specimens may increase the rate of celiac disease detection. The spectrum of celiac disease likely includes a minority of patients with mild enteropathy. A practical seven-item instrument may facilitate standardized evaluation of gluten-free diet adherence. Finally, refractory celiac disease, although rare, is associated with a poor prognosis.

SUMMARY

Celiac disease is a global health problem that requires a multidisciplinary and increasingly cooperative multinational research effort.

Gliadin-primed CD4+CD45RBlowCD25- T cells drive gluten-dependent small intestinal damage after adoptive transfer into lymphopenic mice

BACKGROUND AND AIMS

Coeliac disease is a common small intestinal inflammatory disorder that results from a breach of intestinal tolerance to dietary gluten proteins, driven by gluten-reactive effector T cells. We aimed to assess the pathogenic role of gluten-reactive T cells and to generate a model of gluten-induced enteropathy.

METHODS

CD4+CD25- T cell fractions were adoptively transferred into lymphopenic mice, leading to "baseline" small intestinal inflammation.

RESULTS

Rag1-/- recipients of gliadin-presensitised CD4+CD45RBlowCD25- T cells, but not CD4+CD45RBhigh naive T cells, gained less weight and suffered from more severe duodenitis when challenged with oral gluten than recipients on gluten-free diet, or recipients of control (ovalbumin)-presensitised T cells. This was accompanied by deterioration of mucosal histological features characteristic of coeliac disease, and increased Th1/Th17 cell polarisation in the duodenum and the periphery. Interestingly, reintroduction of a gluten-free diet led to weight gain, improvement of histological duodenitis, and a decrease in duodenal interferon gamma and interleukin 17 transcripts. Moreover, B cell-competent nude recipients of gliadin-presensitised CD4+CD45RBlowCD25- T cells produced high levels of serum anti-gliadin immunoglobulin A (IgA) and IgG1/IgG2c only when challenged with oral gluten.

CONCLUSIONS

CD4+ T cell immunity to gluten leads to a breach of oral gluten tolerance and small intestinal pathology in lymphopenic mice, similar to human coeliac disease. This model will be useful for the study of coeliac disease pathogenesis, and also for testing novel non-dietary therapies for coeliac disease.

Discrepancies between histology and serology for the diagnosis of coeliac disease in a district general hospital: is this an unrecognised problem in other hospitals?

The objective of this study was to assess the increasing number of patients with positive biopsies yet negative serology at Medway Hospital, Kent, through a retrospective data collection. All coeliac serology undertaken between 2003-5 (n=3056) with coeliac positive duodenal biopsy results (n=26) were compared. From the total number of patients with positive duodenal biopsies 10 (38.5%), 13 (50%) and 12 (46.2%) had negative anti-tTg, IgA anti-gliadin and IgG anti-gliadin serology respectively. When combining anti-tTG, IgG and IgA anti-gliadin to improve sensitivity, five patients (19.2%) had completely negative and six (23%) had equivocal serology results. This study shows that a small but significant number of cases of coeliac disease will be missed by relying on serology alone. As the diagnosis and management of disease shifts further towards general physicians and primary care, it is important that the limitations of serological testing are recognised.

Influence of early nutritional components on the development of murine autoimmune diabetes

BACKGROUND/AIMS

Infant diet is suggested to modify autoimmune diabetes risk. The aim of this study was to determine whether infant food components affect diabetes development in the nonobese autoimmune diabetes (NOD) mouse.

METHODS

A basal low-diabetogenic diet was identified by feeding litter-matched female NOD mice standardized diets with and without casein and wheat proteins after weaning. In subsequent trials, basal diet with supplements of wheat (5, 10 and 30%), gluten, wheat globulin/albumin, corn (5%), potato (5%), apple (5%) or carrot (5%) was fed to litter-matched female NOD mice after weaning. Mice were followed for diabetes development and insulin autoantibodies.

RESULTS

A casein- and wheat-free diet was associated with the lowest rate of diabetes development (37% by age 25 weeks). Increased diabetes rates were observed when the basal diet was supplemented with 5% wheat (71% by age 25 weeks; p = 0.023) and 5% corn (57% by age 25 weeks; p = 0.05). Increasing wheat concentrations returned diabetes development to that in basal diet-fed mice. Other food supplements had no or minimal effects on diabetes development.

CONCLUSIONS

Early supplementation of a basal low-diabetogenic diet with low concentrations of the cereals wheat or corn is associated with a moderate increase in the rate of diabetes. Removal of cereals, however, does not abrogate diabetes development in NOD mice.

Trafficking of storage proteins in developing grain of wheat

The processing properties of the wheat flour are largely determined by the structures and interactions of the grain storage proteins (also called gluten proteins) which form a continuous visco-elastic network in dough. Wheat gluten proteins are classically divided into two groups, the monomeric gliadins and the polymeric glutenins, with the latter being further classified into low molecular weight (LMW) and high molecular weight (HMW) subunits. The synthesis, folding and deposition of the gluten proteins take place within the endomembrane system of the plant cell. However, determination of the precise routes of trafficking and deposition of individual gluten proteins in developing wheat grain has been limited in the past by the difficulty of developing monospecific antibodies. To overcome this limitation, a single gluten protein (a LMW subunit) was expressed in transgenic wheat with a C-terminal epitope tag, allowing the protein to be located in the cells of the developing grain using highly specific antibodies. This approach was also combined with the use of wider specificity antibodies to compare the trafficking and deposition of different gluten protein groups within the same endosperm cells. These studies are in agreement with previous suggestions that two trafficking pathways occur in wheat, with the proteins either being transported via the Golgi apparatus into the vacuole or accumulating directly within the lumen of the ER. They also suggest that the same individual protein could be trafficked by either pathway, possibly depending on the stage of development, and that segregation of gluten proteins both between and within protein bodies may occur.

Prolyl endopeptidases

This review describes the structure and function of prolyl endopeptidase (PEP) enzymes and how they are being evaluated as drug targets and therapeutic agents. The most well studied PEP family has a two-domain structure whose unique seven-blade beta-propeller domain works with the catalytic domain to hydrolyze the peptide bond on the carboxyl side of internal proline residues of an oligopeptide substrate. Structural and functional studies on this protease family have elucidated the mechanism for peptide entry between the two domains. Other structurally unrelated PEPs have been identified, but have not been studied in detail. Human PEP has been evaluated as a pharmacological target for neurological diseases due to its high brain concentration and ability to cleave neuropeptides in vitro. Recently, microbial PEPs have been studied as potential therapeutics for celiac sprue, an inflammatory disease of the small intestine triggered by proline-rich gluten.

Antagonists and non-toxic variants of the dominant wheat gliadin T cell epitope in coeliac disease

BACKGROUND

Coeliac disease (CD) is due to an inappropriate T cell mediated response to specific gluten peptides. Measured by interferon gamma (IFN-gamma) ELISPOT, about half of the gliadin specific T cells induced with in vivo wheat gluten exposure in HLA-DQ2+ CD are specific for an alpha/beta-gliadin peptide (p57-73 QE65; QLQPFPQPELPYPQPQS) that includes two overlapping T cell epitopes (PFPQPELPY and PQPELPYPQ).

AIM

To define minimally substituted variants of p57-73 QE65 universally devoid of IFN-gamma stimulatory capacity but capable of antagonising IFN-gamma secretion from polyclonal T cells specific for p57-73 QE65.

METHODS

Peripheral blood mononuclear cells collected from 75 HLA-DQ2+ CD patients after in vivo gluten challenge were used in overnight ELISPOT assays to screen 218 single or double substituted variants of p57-73 QE65 for cytokine stimulatory and antagonist activity.

RESULTS

The region p60-71 (PFPQPELPYPQP) and especially p64-67 (PELP) was sensitive to substitution. Twelve substitutions in p64-67 stimulated no IFN-gamma ELISPOT response. Among 131 partial agonists identified, 45 produced statistically significant inhibition of IFN-gamma ELISPOT responses when cocultured in fivefold excess with p57-73 QE65 (n = 10). Four substituted variants of p57-73 QE65 were inactive by IFN-gamma ELISPOT but consistently antagonised IFN-gamma ELISPOT responses to p57-73 QE65, and also retained interleukin 10 stimulatory capacity similar to p57-73 QE65.

CONCLUSIONS

Altered peptide ligands of p57-73 QE65, identified using polyclonal T cells from multiple HLA-DQ2+ CD donors, have properties in vitro that suggest that a single substitution to certain alpha/beta-gliadins could abolish their capacity to stimulate IFN-gamma from CD4 T cells and also have anti-inflammatory or protective effects in HLA-DQ2+ CD.

Inhibition of HLA-DQ2-mediated antigen presentation by analogues of a high affinity 33-residue peptide from alpha2-gliadin

Human leukocyte antigen DQ2 is a class II major histocompatibility complex protein that plays a critical role in the pathogenesis of Celiac Sprue by binding to epitopes derived from dietary gluten and triggering the inflammatory response of disease-specific T cells. Inhibition of DQ2-mediated antigen presentation in the small intestinal mucosa of Celiac Sprue patients therefore represents a potentially attractive mode of therapy for this widespread but unmet medical need. Starting from a pro-inflammatory, proteolytically resistant, 33-residue peptide, LQLQPFPQPELPYPQPELPYPQPELPYPQPQPF, we embarked upon a systematic effort to dissect the relationships between peptide structure and DQ2 affinity and to translate these insights into prototypical DQ2 blocking agents. Three structural determinants within the first 20 residues of this 33-mer peptide, including a PQPELPYPQ epitope, its N-terminal flanking sequence, and a downstream Glu residue, were found to be important for DQ2 binding. Guided by the X-ray crystal structure of DQ2, the L11 and L18 residues in the truncated 20-mer analogue were replaced with sterically bulky groups so as to retain high DQ2 affinity but abrogate T cell recognition. A dimeric ligand, synthesized by regiospecific coupling of the 20-mer peptide with a bifunctional linker, was identified as an especially potent DQ2 binding agent. Two such ligands were able to attenuate the proliferation of disease-specific T cell lines in response to gluten antigens and, therefore, represent prototypical examples of pharmacologically suitable DQ2 blocking agents for the potential treatment of Celiac Sprue.