INTRODUCTION

Celiac disease (Non tropical sprue, gluten

senseitive enteropathy, Gee-Herter disease) is a

unique autoimmune disorder, unique because the

environmental precipitant is known.

The disorder was previously called celiac sprue,

based on the Dutch word sprue, which was used

to describe a disease similar to tropical sprue that

is characterized by diarrhea, emaciation,

aphthous stomatitis, and malabsorption.

Celiac disease is precipitated, in genetically

predisposed persons, by the ingestion of gluten,

the major storage protein of wheat and similar

grains. Originally considered a rare malabsorption

syndrome of childhood, celiac disease is now

recognized as a common condition that may be

diagnosed at any age and that affects many

organ systems.

Celiac disease results from the interaction between gluten

and immune, genetic, and environmental factors.

The Role of Gluten

Celiac disease is induced by the ingestion of gluten, which

is derived from wheat, barley, and rye. It is comprised of

hundreds of protein components, traditionally classified on

the basis of their solubility in alcohol-water solutions, in

prolamins (alcohol-soluble), and glutenins (alcohol

insoluble) (Wieser, 2007).

Gluten

Prolamins Glutenins

Gliadins, secalins,hordeins

A high content of glutamine and proline is a common

feature of gliadins, secalins and hordeins, while

prolamins of cereals considered to be non-toxic for

persons with CD, such as rice and corn, have a lower

content of these amino acids (Schuppan, 2000).

Undigested molecules of gliadin, such as a peptide from

an α-gliadin fraction made up of 33 amino acids, are

resistant to degradation by gastric, pancreatic, and

intestinal brush-border membrane proteases in the

human intestine.

These peptides pass through the epithelial barrier of the

intestine, possibly during intestinal infections or when

there is an increase in intestinal permeability, and

interact with antigen-presenting cells in the lamina

propria.

MUCOSAL IMMUNE RESPONSES

In patients with celiac disease, immune responses to

gliadin fractions promote an inflammatory reaction,

primarily in the upper small intestine, characterized by

infiltration of the lamina propria and the epithelium with

chronic inflammatory cells and villous atrophy.

This response is mediated by both the innate and the

adaptive immune systems.

The adaptive response is mediated by gliadin-reactive

CD4+ T cells in the lamina propria that recognize gliadin

peptides, which are bound to HLA class II molecules DQ2

or DQ8 on antigen- presenting cells; the T cells

subsequently produce proinflammatory cytokines,

particularly interferon-γ.

Tissue transglutaminase is an enzyme in the intestine

that deamidates gliadin peptides, increasing their

immunogenicity. The ensuing inflammatory cascade

releases metalloproteinases and other tissue-damaging

mediators.

Gliadin peptides also activate an innate immune

response in the intestinal epithelium that is

characterized by increased expression of interleukin- 15

by enterocytes, resulting in the activation of

intraepithelial lymphocytes expressing the activating

receptor NK-G2D, a natural-killer-cell marker.

These activated cells become cytotoxic and kill

enterocytes with surface expression of major-

histocompatibility-complex class I chainrelated A (MIC-

A), a cell-surface antigen induced by stress, such as an

infection.

GENETIC FACTORS

The genetic influence in the pathogenesis of celiac disease is

indicated by its familial occurrence. Celiac disease does not

develop unless a person has alleles that encode for HLA-DQ2

or HLA-DQ8 proteins, products of two of the HLA genes.

However, many people, most of whom do not have celiac

disease, carry these alleles; thus, their presence is necessary

but not sufficient for the development of the disease. Studies

in siblings and identical twins suggest that the contribution of

HLA genes to the genetic component of celiac disease is less

than 50%.

ENVIRONMENTAL FACTORS

These include a protective effect of breast-feeding and the

introduction of gluten in relation to weaning.

The initial administration of gluten before 4 months of age is

associated with an increased risk of disease development, and

the introduction of gluten after 7 months is associated with a

marginal risk. However, the overlap of gluten introduction with

breast-feeding may be a more important protective factor in

minimizing the risk of celiac disease. The occurrence of

certain gastrointestinal infections, such as rotaviral infection,

also increases the risk of celiac disease in infancy

CLINICAL MANIFESTATIONS

Clinical manifestations of celiac disease vary greatly

according to age group. Infants and young children

generally present with diarrhea, abdominal distention,

and failure to thrive. However, vomiting, irritability,

anorexia, and even constipation are also common. Older

children and adolescents often present with

extraintestinal manifestations, such as short stature,

neurologic symptoms, or anemia

Among adults, two to three times as many women have

the disease as men, for unknown reasons. In general,

the prevalence of autoimmune diseases is higher in

women than in men, and iron deficiency and

osteoporosis, each of which prompts an assessment for

celiac disease, are more often diagnosed in women. The

predominance of the disease in women diminishes

somewhat after the age of 65 years

The classic presentation in adults is diarrhea, which may

be accompanied by abdominal pain or discomfort. Other,

silent presentations in adults include iron-deficiency

anemia, osteoporosis etc. Less common presentations

include abdominal pain, constipation, weight loss,

neurologic symptoms, dermatitis herpetiformis,

hypoproteinemia, hypocalcemia, and elevated liver

enzyme levels.

Patients often have symptoms for a long time and

undergo multiple hospitalizations and surgical

procedures before celiac disease is diagnosed

Some cases are diagnosed because of increased

surveillance for celiac disease among people who have a

family history of the disease and among those with

Down syndrome, Turner’s syndrome, or type 1 diabetes,

all of which are associated with celiac disease.

Persons with celiac disease have an increased risk of

autoimmune disorders as compared with the general

population

Case-finding in persons with clinical conditions known to

be associated with CD is currently considered the most

appropriate way to detect atypical cases (Fasano, 2003);

based on their very high diagnostic accuracy, serologic

IgA EMA and IgA anti-tTG tests are the best available

tests for the screening of at-risk individuals (Rostom et

al., 2005).

Diagnosis

The diagnosis of celiac disease requires both a duodenal

biopsy that shows the characteristic findings of

intraepithelial lymphocytosis, crypt hyperplasia, and

villous atrophy and a positive response to a gluten-free

diet.

The diagnostic criteria developed by the European

Society for Pediatric Gastroenterology and Nutrition

require only clinical improvement with the diet, although

histologic improvement on a gluten-free diet is

frequently sought and is recommended in adults

because villous atrophy may persist despite a clinical

response to the diet.

SEROLOGIC TESTING

Indications for serologic testing include:

Unexplained bloating or abdominal distress;

Chronic diarrhea, with or without malabsorption

Or the irritable bowel syndrome;

Abnormalities on laboratory tests that might be caused

by malabsorption (e.g., folate deficiency and iron-

deficiency anemia);

First-degree relatives with celiac disease

The most sensitive antibody tests for the diagnosis of

celiac disease are of the IgA class.

The available tests include those for antigliadin

antibodies, connective-tissue antibodies (antireticulin

and antiendomysial antibodies), and antibodies directed

against tissue transglutaminase, the enzyme responsible

for the deamidation of gliadin in the lamina propria. The

antigliadin antibodies are no longer considered sensitive

enough or specific enough to be used for the detection

of celiac disease, except in children younger than 18

months of age.

The diagnostic standard in celiac serologies remains the

endomysial IgA antibodies; they are highly specific

markers for celiac disease, approaching 100% accuracy.

Overall, the sensitivity of the tests for both endomysial

antibodies and anti–tissue transglutaminase antibodies

is greater than 90%, and a test for either marker is

considered the best means of screening for celiac

disease

BIOPSY

Biopsy of the small intestine remains the standard for

diagnosing celiac disease, and it should always be

performed when clinical suspicion is high, irrespective of

the results of serologic testing. Biopsy confirmation is

crucial, given the lifelong nature of the disease and the

attendant need for an expensive and socially

inconvenient diet.

Who should undergo endoscopic biopsy?

In addition to patients whose serologic tests are positive,

any patient who has chronic diarrhea, iron deficiency, or

weight loss should undergo duodenal biopsy,

irrespective of whether serologic testing for celiac

disease has been performed.

The recognition of endoscopic signs of villous atrophy,

such as scalloping of mucosal folds, absent or reduced

duodenal folds, or a mosaic pattern of the mucosa,

should prompt biopsy.

CAUSES OF VILLOUS ATROPHY OTHER THAN CELIAC DISEASE.

Giardiasis Common-variable immunodeficiency Autoimmune enteropathy Radiation enteritis Tuberculosis Tropical sprue Eosinophilic gastroenteritis Human immunodeficiency virus enteropathy Intestinal lymphoma Zollinger–Ellison syndrome Crohn’s disease Intolerance of foods other than gluten (e.g., milk, soy, chicken,

tuna)

In this paper, they have reviewed studies that

evaluated:

(1) the possibility of using oral mucosa for the initial

diagnosis of CD or for local gluten challenge; and

(2) the possibility of using salivary CD-associated

antibodies as screening tests for the disease.

ORAL MUCOSA FOR INITIAL DIAGNOSIS OF CDOR FOR LOCAL GLUTEN CHALLENGE

Differences in histological features of the oral mucosa of

persons both with and without CD were demonstrated in a

study that involved persons with GFD-treated CD, those with

newly diagnosed CD, and healthy control individuals

(Lähteenoja et al., 1998). Moderate to severe lymphocytic

inflammation was observed in 42.7% of the oral biopsy

specimens from persons with treated CD, as compared with

10% of control individuals.

These results were confirmed in another study by the same

investigators (Lähteenoja et al., 2000), in which the T-cell

count in the epithelium of treated persons was higher than

that in untreated persons and control individuals, and the

mast cell count in the lamina propria of treated persons was

higher than that of untreated persons.

The authors concluded that the oral mucosa cannot be

used for the initial diagnosis of CD, since persons with

untreated CD did not differ from healthy control individuals

with regard to oral mucosal infiltration. In contrast, persons

with treated CD showed significantly increased numbers of T-

cell subsets in their oral mucosa

The observation that, in the oral mucosa of persons with

GFD-treated CD, an immunological ‘memory’ for gluten

hypersensitivity is perpetuated prompted the authors to

evaluate the reaction of the oral mucosa to a local

gluten challenge.

A solution of an a-gliadin-related synthetic peptide was

injected into the buccal submucosa of persons with GFD-

treated CD and healthy control individuals (Lähteenoja

et al., 2000b).

The peptide significantly increased the T-cell counts in the

lamina propria of persons with CD. The numbers of CD3+ and

CD4+ cells were significantly higher after than before peptide

challenge in persons with CD; the expression of the T-cell

activation marker CD25 was also observed in the lamina

propria of these persons after the challenge.

The oral challenge induced no statistically significant

difference in the cell counts of the control individuals.

Importantly, neither the persons with CD nor the control

individuals had any oral complaints or visible changes after

the challenge; similarly, results of the serum EMA test

remained negative after the challenge in all participants.

In another study, the same group performed the oral

gluten challenge both at supramucosal (gliadin powder

applied with an oral adhesive bandage) and submucosal

(injection of gliadin solution) sites (Lähteenoja et al.,

2000c).

After a supramucosal challenge on the oral mucosa of

persons with CD and on GFD, the number of intra-

epithelial CD4+ and CD8+ T-cells increased in 67.6%

and 73% of cases, respectively. Also, there was a

significant increase in the number of CD4+ cells in the

lamina propria of persons with CD.

After a submucosal gliadin challenge, the mean numbers

of total T-cells and CD4+ T-cells were significantly

increased in the lamina propria of persons with CD.

There were no differences in the mean cell counts of the

healthy control individuals after submucosal challenge.

Based on these results, the authors reported a 73%

sensitivity of the submucosal gliadin challenge in

persons with treated CD, and a specificity of 80%; the

positive predictive value was 93%, and the negative

predictive value was 44%.

Recently, results from two groups of investigators have

demonstrated that in vitro culture media of oral mucosa

biopsies from persons with untreated CD can release

IgA-class EMA and anti-tTG (Carroccio et al., 2007;

Vetrano et al., 2007). One of the groups (Carroccio et al.,

2007) found IgA EMA and antitTG in 53.6% and 57.2% of

cultured oral biopsies, respectively. IgA EMA and anti-tTG

assayed on culture media of duodenal biopsies were

positive in all persons with CD

The sensitivity of the EMA test on oral mucosa media

was 53.6%, the specificity was 100%, and the diagnostic

accuracy was 79%. For the anti-tTG test, sensitivity

specificity, and accuracy were 57.2%, 100%, and 79%,

respectively.

SALIVARY CD-ASSOCIATED ANTIBODIESAS SCREENING TESTS

Conflicting results have been reported regarding the

usefulness of measuring CD-associated antibodies in saliva to

screen for CD.

In 1989, IgA-class AGA levels in whole unstimulated saliva of

persons with untreated CD were significantly higher than

those of both persons with GFD-treated CD and individuals

without CD, with a reported diagnostic accuracy of 100% (al-

Bayaty et al., 1989). A similar result was obtained in a study

where a sensitivity of 100% was assumed, and the salivary

test for IgA AGA had a 90% specificity (Hakeem et al., 1992).

In addition, two studies that tested stimulated parotid

secretion, and not unstimulated whole saliva, reported

only little (O’Mahony et al., 1991) or no (Gibney and

Brady, 1991) elevation of IgA AGA levels in persons with

untreated CD.

Both IgA and IgG salivary AGA has been measured in

persons with treated and untreated CD; although

specificities were relatively high (93.3% for both IgA and

IgG), sensitivities were poor (50% for IgG, 61.2% for IgA)

(Rujner et al., 1996).

As to tTG antibodies, their presence in saliva was evaluated in

four studies, with different results. By means of a fluidphase

radio-immunoassay, IgA anti-tTG was detected in saliva from

97.4% of persons with untreated CD, while none of the saliva

samples from healthy control individuals was found to be IgA

anti-tTG-positive (Bonamico et al., 2004).

In contrast, an enzyme-linked immunosorbent assay (ELISA)

test detected IgA anti-tTG antibodies in saliva from persons

with CD and with low sensitivity (Baldas et al., 2004). A recent

study that used a commercial solid-phase ELISA test has

reported a sensitivity of 90% and a specificity of 96.7%

(Ocmant and Mascart, 2007).

Serum radioimmunoassay (RIA) tissue transglutaminase

autoantibodies (tTG-Abs) proved to be a sensitive test

during coeliac disease (CD) follow-up. This study

demonstrates that it is possible to detect salivary tTG-

Abs with high sensitivity not only at CD diagnosis, but

also during GFD. (M. BONAMICO, R. NENNA, R. P. L.

LUPARIA, C. PERRICONE, M. MONTUORI, F. LUCANTONI,A.

CASTRONOVO, S. MURA , A. TURCHETTI , P. STRAPPINI &

C. TIBERTI 2008)

DISCUSSION Histological examination of the oral mucosa of persons with

untreated CD did not show any significant alteration

(Lähteenoja et al., 2000a); consequently, the oral mucosa

cannot be used for an initial diagnosis of CD.

Nevertheless, the recent demonstration that the oral mucosa

of persons with untreated CD can produce IgA-class EMA and

anti-tTG in culture media (Carroccio et al., 2007; Vetrano et

al., 2007) offers a new approach for using the oral mucosa to

diagnose CD, although there are conflicting results regarding

the sensitivity of the tests

Evidence exists that activated B-cells can migrate from

gut-associated lymphoid tissue (GALT) to salivary glands

(Brandtzaeg, 2007a), and IgA-producing gliadin-specific

lymphocytes have been detected in the peripheral blood

of children with CD (Hansson et al., 1997). In view of this

‘plasmablast’ trafficking throughout the body, the

presence of CD-associated antibodies in saliva would

seem plausible

Oral mucosa and salivary glands are effector sites of the

mucosal immune system; the inductive sites of the

mucosal immune system consist of organized mucosa-

associated lymphoid tissue (MALT) (Johansen et al.,

2007).

Although GALT is the largest and most important part of

MALT, and primed lymphocytes can migrate from GALT

to salivary glands (Brandtzaeg, 2007a), there is now

compelling evidence that supports the

compartmentalization of the mucosal immune system

(Brandtzaeg and Johansen, 2005; Johansen et al., 2007).

Therefore, activated immune cells seem to home

preferentially to the sites where they were originally primed

(Brandtzaeg, 2007b). In this view, nasopharynx-associated

lymphoid tissue (NALT) and bronchus-associated lymphoid

tissue (BALT) may be more important than GALT in inducing an

immune response in the upper aerodigestive tract.

Moreover, a duct associated lymphoid tissue (DALT) of the

salivary glands has been described (Nair and Schroeder,

1986; Ciccone et al., 1998). It is accessible to oral antigens by

retrograde passage through salivary ducts; thus, DALT could

have an independent role in the gluten-related immune

response in the oral cavity (Baldas et al., 2004).

TREATMENT

Nutritional therapy, the only accepted treatment for

celiac disease, involves the lifelong elimination of wheat,

rye, and barley from the diet.

Fundamentals of the Gluten-free Diet.Grains that should be avoided Wheat, rye, barley (including malt)

Safe grains (gluten-free) Rice, buckwheat, corn, millet, quinoa, sorghum, teff (an

Ethiopian cereal grain), oats

Sources of gluten-free starches that can be used as flour alternatives

Cereal grains: amaranth, buckwheat, corn (polenta), millet, quinoa, sorghum, teff, rice (white, brown, wild, basmati, jasmine), montina (Indian rice grass)

Tubers: arrowroot, jicama, taro, potato, tapioca (cassava, manioc, yucca)

Legumes: chickpeas, lentils, kidney beans, navy beans, pea beans, peanuts,soybeans

Nuts: almonds, walnuts, chestnuts, hazelnuts, cashews Seeds: sunflower, flax, pumpkin

PROBLEMS OF DIETARY ADHERENCE High cost Poor availability of gluten-free products (in developing

countries) Poor palatability Absence of symptoms when dietary restrictions not observed Inadequate information on gluten content of food or drugs Inadequate dietary counseling Inadequate initial information supplied by diagnosing

physician Inadequate medical or nutritional follow-up Lack of participation in a support group Inaccurate information from physicians, dietitians, support

groups, or Internet Dining out of the home Social, cultural, or peer pressures Transition to adolescence Inadequate medical follow-up after childhood

CAUSES OF POORLY RESPONSIVE CELIAC DISEASE

Incorrect diagnosis Gluten ingestion (intentional or unintentional) Microscopical colitis Lactose intolerance Pancreatic insufficiency Bacterial overgrowth Intolerance of foods other than gluten (e.g., fructose, milk,

soy) Inflammatory bowel disease Irritable bowel syndrome Anal incontinence Autoimmune enteropathy Refractory celiac disease (with or without clonal T cells) Enteropathy-associated T-cell lymphoma

CONCLUSION Celiac disease occurs in nearly 1% of the population in

many countries. Increasing awareness of the

epidemiology and diverse manifestations of the disease,

as well as the availability of sensitive and specific

serologic tests, especially among primary care

physicians, will lead to more widespread screening and

diagnosis, which in turn will lead to greater availability of

gluten-free foods and efforts to develop drug therapies

that relieve patients of the burden of a gluten-free diet.

There is no consensus regarding the accuracy of a salivary

CD-associated antibody test in screening for CD. Lack of

standardized collection, handling, storage, and analysis

methods seems to affect the reliability and reproducibility of

the reported results.

Further studies should also investigate whether the oral

gluten-sensitized lymphocytes do originate exclusively from

homing of cells primed in gut-associated lymphoid tissue, or,

rather, whether they could also be primed directly in the oral

cavity. The latter would have important implications not only

for diagnostics, but also for the understanding of CD in

general.

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