The pathology of malabsorption: current concepts

Acute gastrointestinal permeability after traumatic brain injury in mice precedes a bloom in Akkermansia muciniphila supported by intestinal hypoxia

Traumatic brain injury (TBI) increases gastrointestinal morbidity and associated mortality. Clinical and preclinical studies implicate gut dysbiosis as a consequence of TBI and an amplifier of brain damage. However, little is known about the association of gut dysbiosis with structural and functional changes of the gastrointestinal tract after an isolated TBI. To assess gastrointestinal dysfunction, mice received a controlled cortical impact or sham brain injury and intestinal permeability was assessed at 4 h, 8 h, 1 d, and 3 d after injury by oral administration of 4 kDa FITC Dextran prior to euthanasia. Quantification of serum fluorescence revealed an acute, short-lived increase in permeability 4 h after TBI. Despite transient intestinal dysfunction, no overt morphological changes were evident in the ileum or colon across timepoints from 4 h to 4 wks post-injury. To elucidate the timeline of microbiome changes after TBI, 16 s gene sequencing was performed on DNA extracted from fecal samples collected prior to and over the first month after TBI. Differential abundance analysis revealed that the phylum Verrucomicrobiota was increased at 1, 2, and 3 d after TBI. The Verrucomicrobiota species was identified by qPCR as Akkermansia muciniphila, an obligate anaerobe that resides in the intestinal mucus bilayer and produces short chain fatty acids (e.g. butyrate) utilized by intestinal epithelial cells. We postulated that TBI promotes intestinal changes favorable for the bloom of A. muciniphila. Consistent with this premise, the relative area of mucus-producing goblet cells in the medial colon was significantly increased at 1 d after injury, while colon hypoxia was significantly increased at 3 d. Our findings reveal acute gastrointestinal functional changes coupled with an increase of beneficial bacteria suggesting a potential compensatory response to systemic stress after TBI.

American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease

This guideline presents an update to the 2013 American College of Gastroenterology Guideline on the Diagnosis and Management of Celiac Disease with updated recommendations for the evaluation and management of patients with celiac disease (CD). CD is defined as a permanent immune-mediated response to gluten present in wheat, barley, and rye. CD has a wide spectrum of clinical manifestations that resemble a multisystemic disorder rather than an isolated intestinal disease, and is characterized by small bowel injury and the presence of specific antibodies. Detection of CD-specific antibodies (e.g., tissue transglutaminase) in the serum is very helpful for the initial screening of patients with suspicion of CD. Intestinal biopsy is required in most patients to confirm the diagnosis. A nonbiopsy strategy for the diagnosis of CD in selected children is suggested and discussed in detail. Current treatment for CD requires strict adherence to a gluten-free diet (GFD) and lifelong medical follow-up. Most patients have excellent clinical response to a GFD. Nonresponsive CD is defined by persistent or recurrent symptoms despite being on a GFD. These patients require a systematic workup to rule out specific conditions that may cause persistent or recurrent symptoms, especially unintentional gluten contamination. Refractory CD is a rare cause of nonresponsive CD often associated with poor prognosis.

Exocrine Pancreatic Insufficiency Following Gastric Resectional Surgery-is Routine Pancreatic Enzyme Replacement Therapy Necessary?

The data on exocrine pancreatic insufficiency (EPI) following gastric resectional surgery is variable, ranging from 26% to as high as 100%. This study aimed to document symptomatic EPI following gastric resectional surgery and to objectively document EPI, by fecal elastase (FE) testing. This was a cross-sectional study among patients undergoing gastric resection for adenocarcinoma of the stomach, at the Upper Gastrointestinal Surgical Unit at the Christian Medical College Hospital, Vellore, India. A detailed questionnaire was administered to the patients in the postoperative period, to evaluate clinical symptoms of EPI. Further, study participants were tested for FE pre- and postoperatively. Of the 60 patients in this study, the postoperative questionnaire administered to all patients during follow up. None showed symptoms suggestive of EPI. Pre- and post-operative FE testing were feasible in 27 of the 60 patients, which showed a 33% incidence of EPI. None of the patients had clinical symptoms of EPI, following gastric resectional surgery, on short-term follow-up. However, more than a third of the patients tested developed asymptomatic EPI after gastric resectional surgery, based on FE testing. This may be explained by the fact that in the early postoperative period, EPI following gastric resectional surgery perhaps has a mild, subclinical presentation. Therefore routine pancreatic supplementation after gastric resectional surgery may not be necessary. However, one needs to carefully look for worsening of symptoms of EPI on long-term follow-up, which may necessitate appropriate investigations followed by pancreatic enzyme replacement therapy.

The role of histopathology in the diagnosis and management of coeliac disease and other malabsorptive conditions

Most absorption of nutrients takes place in the proximal small intestine, and the most common disorders leading to malabsorption are associated with a morphological abnormality in the duodenal mucosa that is appreciable in histological sections of biopsy specimens. Coeliac disease is the most well-known example, causing intraepithelial lymphocytosis, inflammation and villous atrophy in the duodenum. Remarkably similar inflammatory changes can be induced by other processes, including medications, e.g. angiotensin II receptor blockers and immune checkpoint inhibitors, immune dysregulation disorders, e.g. common variable immunodeficiency and autoimmune enteropathy, infections, collagenous sprue, and tropical sprue. However, there are often subtle histological differences from coeliac disease in the type of inflammatory infiltrate, the presence of crypt apoptosis, and the extent and type of inflammation beyond the duodenum. The clinical setting and serological investigation usually allow diagnostic separation, but some cases remain challenging. Histopathology is also important in assessing the response to treatment, such as the change in villous architecture caused by a gluten-free diet, or the response to cessation of a potentially causative medication. This review examines the practical role that histopathology of duodenal biopsy specimens plays in the assessment and management of inflammatory malabsorptive processes of the proximal small intestine, with a particular emphasis on coeliac disease.

[Autoimmune enteropathy in adults : A rare and difficult but relevant differential diagnosis of chronic diarrhea]

Autoimmune enteropathy (AIE) was originally believed to be a pediatric disease until there were increasing numbers of adult cases reported over the last 20 years. AIE is an autoimmune disease that manifests as severe chronic diarrhea.The histological hallmark is villous atrophy. Histology alone is not sufficiently sensitive and consistent. Four different histological patterns are known. There are many differential diagnoses to be considered relating to both histology and symptoms.We present the case of a young woman with fatal AIE and homozygous germline-mutation of the CLEC7A gene. The course of disease is documented in multiple intestinal biopsies, which show a morphological change over time.Histology and symptoms often resemble celiac disease. In order to recognize this rare disease early in its course there is a need for a special awareness among attending physicians and pathologists.

Mechanisms underlying reduced weight gain in intestinal fatty acid-binding protein (IFABP) null mice

Intestinal-fatty acid binding protein (IFABP; FABP2) is a 15-kDa intracellular protein abundantly present in the cytosol of the small intestinal (SI) enterocyte. High-fat (HF) feeding of IFABP-/- mice resulted in reduced weight gain and fat mass relative to wild-type (WT) mice. Here, we examined intestinal properties that may underlie the observed lean phenotype of high fat-fed IFABP-/- mice. No alterations in fecal lipid content were found, suggesting that the IFABP-/- mice are not malabsorbing dietary fat. However, the total excreted fecal mass, normalized to food intake, was increased for the IFABP-/- mice relative to WT mice. Moreover, intestinal transit time was more rapid in the IFABP-/- mice. IFABP-/- mice displayed a shortened average villus length, a thinner muscularis layer, reduced goblet cell density, and reduced Paneth cell abundance. The number of proliferating cells in the crypts of IFABP-/- mice did not differ from that of WT mice, suggesting that the blunt villi phenotype is not due to alterations in proliferation. IFABP-/- mice were observed to have altered expression of genes and proteins related to intestinal structure, while immunohistochemical analyses revealed increased staining for markers of inflammation. Taken together, these studies indicate that the ablation of IFABP, coupled with high-fat feeding, leads to changes in gut motility and morphology, which likely contribute to the relatively leaner phenotype occurring at the whole-body level. Thus, IFABP is likely involved in dietary lipid sensing and signaling, influencing intestinal motility, intestinal structure, and nutrient absorption, thereby impacting systemic energy metabolism.NEW & NOTEWORTHY Intestinal fatty acid binding protein (IFABP) is thought to be essential for the efficient uptake and trafficking of dietary fatty acids. In this study, we demonstrate that high-fat-fed IFABP-/- mice have an increased fecal output and are likely malabsorbing other nutrients in addition to lipid. Furthermore, we observe that the ablation of IFABP leads to marked alterations in intestinal morphology and secretory cell abundance.

Prevalence and associated factors of small intestinal bacterial overgrowth among systemic sclerosis patients

BACKGROUND

Small intestinal bacterial overgrowth (SIBO) results in nutrient malabsorption and malnutrition, thereby increasing the morbidity and mortality in systemic sclerosis (SSc) patients.

OBJECTIVES

To evaluate the prevalence and associated factors of SIBO in SSc patients.

METHOD

A cross-sectional study was conducted between July 2015 and January 2016 in SSc patients over 18, using the glucose H₂ /CH₄ breath test to evaluate SIBO.

RESULTS

Eighty-nine SSc patients (30 male and 59 female) underwent the glucose H₂ /CH₄ breath test. The mean age was 54.4. Twelve participants were positive for the glucose H₂ /CH₄ breath test, yielding a SIBO prevalence of 13.5% (95% CI 7.2-22.4) among SSc patients. A multivariate analysis revealed that duration of disease >5 years was significantly associated with SIBO (adjusted odds ratio 9.38; 95% CI 1.09-80.47).

CONCLUSION

The prevalence of SIBO, using the glucose H₂ /CH₄ breath test, is not common among Thai SSc patients. However, a positive result was associated with longer duration of disease.

Classification chaos in coeliac disease: Does it really matter?

The spectrum of mucosal pathology in coeliac disease (CD), initially defined by Marsh in 1992 has been subjected to several modifications in the following years by Oberhuber, then by Corazza and Villanaci, and finally by Ensari. The present study, aimed to end the ongoing confusion regarding the classification of mucosal pathology in CD by applying all the classifications proposed so far on a large series of cases. A total of 270 duodenal biopsies taken from the distal duodenum of patients with a diagnosis of CD were included in the study. All biopsies were classified according to Marsh, Oberhuber, Corazza Villanaci, and Ensari classification schemes. For statistical analyses cases were divided into three groups: Group 1 included type 1 lesions in Marsh, Ensari, and Oberhuber and grade A in Corazza Villanaci classifications. Group 2 comprised of type 2 lesions in Marsh and Ensari classifications together with type2, type 3a and 3b lesions in Oberhuber classification and grade B1 lesions in Corazza Villanaci classification. Group 3 included type 3 lesions in Marsh and Ensari classifications, and type 3c lesions in Oberhuber, and grade B2 lesions in Corazza Villanaci classifications. The kappa value was 1.00 (excellent) for group 1, 0.53 (fair) for group 2 and 0.78 (excellent) for group 3 (p<0.0001). These results suggest that any of the above classification system would serve similar purposes in the diagnosis of CD. Therefore, it is advisable that the pathologist should use the simplest reliable scheme.

Disorders associated with malabsorption of iron: A critical review

Malabsorption is a disorder of the gastrointestinal tract that leads to defective digestion, absorption and transport of important nutrients across the intestinal wall. Small intestine is the major site where most of the nutrients are absorbed. There are three main mechanisms of malabsorption; premucosal, mucosal and postmucosal. Premucosal malabsorption is the inadequate digestion due to improper mixing of gastrointestinal enzymes and bile with chyme. This could be because of surgical resection of the small intestine or a congenital deficiency of the enzymes and bile responsible for digestion e.g. postgastrectomy, chronic pancreatitis, pancreatic cancer, cystic fibrosis, gallstones, cholangitis etc. Mucosal malabsorption occurs in celiac disease, tropical sprue, Crohn's disease etc. Postmucosal condition arises due to impaired nutrients transport e.g. intestinal lymphangiectasia, macroglobulinemia etc. Disorders of malabsorption lead to decreased iron absorption and produce iron deficiency anemia. Using the index terms malabsorption, postgastrectomy, chronic pancreatitis, pancreatic cancer, cystic fibrosis, gallstones, cholangitis, celiac disease, tropical sprue, Crohn's disease intestinal lymphangiectasia, macroglobulinemia and iron deficiency anemia the MEDLINE and EMBASE databases were searched. Additional data sources included bibliographies and references of identified articles.

Investigation of Morphological and Functional Changes in the Small Intestine With Pancreatic Disease

OBJECTIVES

The aim of this study was to investigate the relationship between pancreas and small intestine evaluating the endoscopic and histopathologic findings of the proximal small intestine in pancreatic diseases.

METHODS

Fifty patients (18 patients with chronic pancreatitis, 17 patients with pancreatic cancer, 15 control subjects) underwent enteroscopy using a prototype enteroscope. The villous height of the jejunum on bioptic specimens was measured, and the mean values of the villi were compared among the 3 groups. Exocrine function was calculated by the pancreatic function diagnostic test, and the correlation between the recovery rate of p-aminobenzoic acid and the villous height was assessed. Finally, the distribution of the K cells secreting glucose-dependent insulinotropic polypeptide and the L cells secreting glucagon-like peptide 1 in the duodenum and jejunum was investigated using immunohistochemistry for glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1.

RESULTS

The mean villous height in chronic pancreatitis (328 ± 67 μm) was significantly lower than that in pancreatic cancer (413 ± 57 μm) and control subjects (461 ± 97 μm) (P = 0.004 and P < 0.0001, respectively). A positive correlation was found between the recovery rate of p-aminobenzoic acid and the villous height (r = 0.52, P = 0.0001). The presence of K and L cells was verified in the duodenum and the jejunum.

CONCLUSIONS

Close relationship between pancreas and small intestine was demonstrated.

Malabsorption of iron as a cause of iron deficiency anemia in postmenopausal women

Objective:

Malabsorption is one of the causes of iron deficiency anemia in postmenopausal women. The main objective of this study was to access the frequency of malabsorption in iron deficient anemic postmenopausal women.

Methods:

A total of 123 postmenopausal women were enrolled in the study. Of these 123 women, 50 were included as ‘control group’ and 73 patients with comparable severity of anemia were the ‘patient group’. Two tablets of ferrous sulfate (200 mg/tablet) along with one tablet of vitamin C (500 mg) were given to all participants. Serum iron levels were determined on samples collected from all participants before and after the administration of ferrous sulfate. Difference between before and after serum iron levels of normal and patients were compared.

Results:

No change in serum iron between sample one and sample two represented malabsorption. Out of 73, 5 postmenopausal anemic patients showed no change in their serum iron level after the administration of ferrous sulfate. This study shows that frequency of malabsorption of iron in postmenopausal women is 6.8%.

Conclusion:

Malabsorption should be considered as a prevalent cause of iron deficiency anemia in postmenopausal women. It should be properly diagnosed and iron response should be monitored properly in postmenopausal women with IDA after oral iron therapy. If a postmenopausal woman does not show any response to oral iron therapy, she should be evaluated for iron loss (blood loss and/or malabsorption). Intravenous route should be used for the administration of iron in these patients.

Quantitative image analysis of celiac disease

We outline the use of quantitative techniques that are currently used for analysis of celiac disease. Image processing techniques can be useful to statistically analyze the pixular data of endoscopic images that is acquired with standard or videocapsule endoscopy. It is shown how current techniques have evolved to become more useful for gastroenterologists who seek to understand celiac disease and to screen for it in suspected patients. New directions for focus in the development of methodology for diagnosis and treatment of this disease are suggested. It is evident that there are yet broad areas where there is potential to expand the use of quantitative techniques for improved analysis in suspected or known celiac disease patients.

Microbes and B cell development

Animals and many of their chronic microbial inhabitants form relationships of symbiotic mutualism, which occurs when coexisting life-forms derive mutual benefit from stable associations. While microorganisms receive a secure habitat and constant food source from vertebrate hosts, they are required for optimal immune system development and occupy niches otherwise abused by pathogens. Microbes have also been shown to provide vertebrate hosts with metabolic capabilities that enhance energy and nutrient uptake from the diet. The immune system plays a central role in the establishment and maintenance of host-microbe homeostasis, and B lineage cells play a key role in this regulation. Here, I reviewed the structure and function of the microbiota and the known mechanisms of how nonpathogenic microbes influence B cell biology and immunoglobulin repertoire development early in life. I also discuss what is known about how B lineage cells contribute to the process of shaping the composition of commensal/mutualistic microbe membership.

The Malabsorption Syndrome and Its Causes and Consequences

The indication for a small intestinal biopsy is usually the work-up of malabsorption, a clinicopathologic picture caused by a number of infectious and noninfectious inflammatory conditions. The biopsy is generally taken through an endoscope, by either forceps or suction, from the duodenum or proximal jejunum. Depending upon the underlying condition, morphological abnormalities are seen in malabsorption range from normal mucosa with increased intraepithelial lymphocytes (gluten-sensitive enteropathy, viral gastroenteritis, food allergies, etc.), villous shortening with crypt hyperplasia (celiac disease (CD), treated CD, tropical sprue, and bacterial overgrowth), to completely flat mucosa (CD, refractory sprue, enteropathy-induced T-cell lymphoma, and autoimmune enteropathy). Infectious agents that affect gastrointestinal tract can be grouped as food-borne and water-borne bacteria, opportunistic infections (bacterial, fungal, and viral), viral infections (extremely rarely biopsied), and parasitic and helminthic infections. The majority of these infections are, however, self-limited. Although biopsy is more invasive, the use of this procedure allows detection of other causes, including Whipple's disease, other protozoan forms of diarrhea (e.g., cryptosporidiosis, isosporiasis, or cyclosporiasis), Crohn's disease, or lymphoma that may also present as diarrhea and malabsorption.

Evaluation of the ultrastructure of the small intestine of hiv infected children by transmission and scanning electronic microscopy

OBJECTIVES

To describe HIV children's small intestinal ultrastructural findings.

METHODS

Descriptive, observational study of small intestine biopsies performed between August 1994 and May 1995 at São Paulo, SP, Brazil. This material pertained to 11 HIV infected children and was stored in a laboratory in paraffin blocks. Scanning and transmission electronic microscopy were used to view those intestine samples and ultrastructural findings were described by analyzing digitalized photos of this material. Ethical Committee approval was obtained.

RESULTS

In most samples scanning microscopy showed various degrees of shortening and decreasing number of microvilli and also completes effacements in some areas. Derangement of the enterocytes was seen frequently and sometimes cells well defined borders limits seemed to be loosened. In some areas a mucous-fibrin like membrane with variable thickness and extension appeared to partially or totally coat the epithelial surface. Fat drops were present in the intestinal lumen in various samples and a bacterium morphologically resembling bacilli was seen in two occasions. Scanning microscopy confirmed transmission microscopy microvilli findings and also showed little "tufts" of those structures. In addition, it showed an increased number of vacuoles and multivesicular bodies inside various enterocytes, an increased presence of intraepithelial lymphocytes, mitochondrial vacuolization and basement membrane enlargement in the majority of samples analyzed. However, some samples exhibited normal aspect.

CONCLUSIONS

Our study showed the common occurrence of various important intestinal ultrastructural alterations with variable degrees among HIV infected children, some of them in our knowledge not described before.

Immunohistochemical stains for CD3 and CD8 do not improve detection of gluten-sensitive enteropathy in duodenal biopsies

Patients with gluten-sensitive enteropathy usually have increased numbers of duodenal intraepithelial lymphocytes even if the villous architecture is normal. Some authors advocate the use of CD8 and CD3 immunohistochemical stains to improve detection of intraepithelial lymphocytosis, yet the added value of immunohistochemistry when biopsies appear normal remains unproven. The purpose of this study was to evaluate the utility of CD3 and CD8 immunostains in detecting intraepithelial lymphocytosis among duodenal biopsies originally interpreted to be normal based on routine evaluation. We identified 200 duodenal biopsies from 172 patients, all of which were accompanied by a clinical question of gluten-sensitive enteropathy. Five well-oriented villi from each biopsy were assessed. Intraepithelial lymphocytes present in hematoxylin and eosin (H&E)-stained slides were counted and compared with the number of CD3 and CD8 immunopositive cells present in the villous epithelium. Results were expressed as the mean number of intraepithelial lymphocytes or immunopositive cells present per 20 villous tip enterocytes. Review of H&E-stained slides revealed a mean of 2.1 ± 0.1 intraepithelial lymphocytes, compared with 3.2 ± 0.1 CD3-positive and 2.1 ± 0.1 CD8-positive intraepithelial cells (P=<0.001 and 1, respectively), although none of the cases displayed sufficient numbers of intraepithelial lymphocytes to be considered abnormal (ie, ≥ 12/20 enterocytes) by any method. The number of intraepithelial lymphocytes detected by H&E evaluation or immunohistochemistry did not correlate with results of serologic studies for markers of gluten sensitivity. We conclude that immunostains for T cell markers do not improve detection of gluten-sensitive enteropathy when H&E-stained sections are normal.

A presentation of latent tropical sprue in a Canadian hospital

Tropical sprue (TS) is a chronic diarrheal disease of unknown etiology characterized by malabsorption and small bowel mucosal abnormalities. TS affects residents of, and visitors to, endemic tropical regions. Rarely the disease may remain latent for several years, and to date, few cases of latent TS have been reported in Europe or North America. However, in our increasingly multicultural communities and in a 'global village' where travel is common, clinicians must maintain a high index of suspicion for TS in patients presenting with diarrhea and malabsorption who have traveled to endemic regions. TS may mimic common diarrheal diseases that are seen in developed nations, including celiac disease, Crohn's disease, bacterial overgrowth, and other infectious etiologies. Accordingly, once these more common etiologies have been ruled out, TS must be considered in patients presenting with diarrhea after travel to endemic regions. We present a unique Canadian case of latent TS, with a brief review of the diagnostic approach and treatment.

ACG clinical guidelines: diagnosis and management of celiac disease

This guideline presents recommendations for the diagnosis and management of patients with celiac disease. Celiac disease is an immune-based reaction to dietary gluten (storage protein for wheat, barley, and rye) that primarily affects the small intestine in those with a genetic predisposition and resolves with exclusion of gluten from the diet. There has been a substantial increase in the prevalence of celiac disease over the last 50 years and an increase in the rate of diagnosis in the last 10 years. Celiac disease can present with many symptoms, including typical gastrointestinal symptoms (e.g., diarrhea, steatorrhea, weight loss, bloating, flatulence, abdominal pain) and also non-gastrointestinal abnormalities (e.g., abnormal liver function tests, iron deficiency anemia, bone disease, skin disorders, and many other protean manifestations). Indeed, many individuals with celiac disease may have no symptoms at all. Celiac disease is usually detected by serologic testing of celiac-specific antibodies. The diagnosis is confirmed by duodenal mucosal biopsies. Both serology and biopsy should be performed on a gluten-containing diet. The treatment for celiac disease is primarily a gluten-free diet (GFD), which requires significant patient education, motivation, and follow-up. Non-responsive celiac disease occurs frequently, particularly in those diagnosed in adulthood. Persistent or recurring symptoms should lead to a review of the patient's original diagnosis to exclude alternative diagnoses, a review of the GFD to ensure there is no obvious gluten contamination, and serologic testing to confirm adherence with the GFD. In addition, evaluation for disorders associated with celiac disease that could cause persistent symptoms, such as microscopic colitis, pancreatic exocrine dysfunction, and complications of celiac disease, such as enteropathy-associated lymphoma or refractory celiac disease, should be entertained. Newer therapeutic modalities are being studied in clinical trials, but are not yet approved for use in practice. Given the incomplete response of many patients to a GFD-free diet as well as the difficulty of adherence to the GFD over the long term, development of new effective therapies for symptom control and reversal of inflammation and organ damage are needed. The prevalence of celiac disease is increasing worldwide and many patients with celiac disease remain undiagnosed, highlighting the need for improved strategies in the future for the optimal detection of patients.

Protein-losing enteropathy in a dog with lymphangiectasia, lymphoplasmacytic enteritis and pancreatic exocrine insufficiency

This is a report of seven-year-old male Akita mixed dog, with protein-losing enteropathy (PLE). He had a history of chronic vomiting and diarrhea with anorexia/hyporexia. Previously he suffered acute abdomen about eight months prior to this visit. Our dog showed uncommon combination of diseases that could cause PLE since it was affected by inflammatory bowel disease (IBD), intestinal lymphangiectasia (IL), and exocrine pancreatic insufficiency (EPI). The dog had most of the abnormalities found in IL, as well as hypoalbuminemia, hyperglobulinemia, lymphopenia, hypocalcemia, and hypercholesterolemia. During endoscopy exam, we found changes characteristic of IL such as irregular small white spots. We took biopsies from stomach, duodenum, and cecum. These biopsies showed infiltration by lymphocytes and plasmatic cells in the lamina propria also, the duodenal biopsies showed moderate dilation of the lymphatic vessels. The patient had 2.1 µg/mL of TLI, this result was compatible with EPI. We assume that the first pathology in this animal was IBD, which caused chronic pancreatitis (CP) that in turn progressed to EPI. It is also possible that IL was secondary to IBD. We have reported for the first time the correlation of IBD and EPI in dogs. This should change our approach to treating chronic diarrhea in dogs. Therefore, we propose that dogs diagnosed with EPI should also be subjected to endoscopy and intestinal biopsy. Similarly, to rule out secondary EPI, TLI should be measured routinely in dogs with IBD.

Crosstalk between B lymphocytes, microbiota and the intestinal epithelium governs immunity versus metabolism in the gut

Using a systems biology approach, we discovered and dissected a three-way interaction between the immune system, the intestinal epithelium and the microbiota. We found that, in the absence of B cells, or of IgA, and in the presence of the microbiota, the intestinal epithelium launches its own protective mechanisms, upregulating interferon-inducible immune response pathways and simultaneously repressing Gata4-related metabolic functions. This shift in intestinal function leads to lipid malabsorption and decreased deposition of body fat. Network analysis revealed the presence of two interconnected epithelial-cell gene networks, one governing lipid metabolism and another regulating immunity, that were inversely expressed. Gene expression patterns in gut biopsies from individuals with common variable immunodeficiency or with HIV infection and intestinal malabsorption were very similar to those of the B cell-deficient mice, providing a possible explanation for a longstanding enigmatic association between immunodeficiency and defective lipid absorption in humans.

Clinical value of duodenal biopsies--beyond the diagnosis of coeliac disease

At upper gastrointestinal endoscopy to investigate unexplained diarrhea and iron deficiency anemia, duodenal biopsies are often taken to exclude a diagnosis of coeliac disease. While histology remains the gold standard for this diagnosis, recent developments in serological testing may overtake this as a first line test and biopsy restricted to confirming the diagnosis. Established coeliac disease on biopsy is straightforward, but early lesions may pose a challenge. Newer endoscopic procedures such as push-pull enteroscopy (balloon enteroscopy) with biopsy allow access to the small bowel beyond the second part of the duodenum. Controversy remains as to what constitutes the normal histology of the duodenum, and small bowel. Lymphocytic duodenosis (increased intraepithelial lymphocytes with normal villous architecture) in patients with negative coeliac serology can be associated with Helicobacter pylori, drugs, autoimmune and other diseases including food allergy. Full thickness small intestinal biopsies can aid in investigation of enteric neuropathies in severe dysmotility disorders. Biopsies are also taken to investigate malabsorption due to suspected infectious and metabolic disorders. Despite highly active anti-retroviral therapy (HAART), immunosuppressed patients may be affected by duodenal pathogens. The histology of duodenal mucosa in acid related disorders reflects the damage seen at endoscopy. Although the prevalence of duodenal ulcer disease is decreasing, drugs causing ulceration remain an important disease entity. Recent observations in functional bowel disorders suggest that the duodenum may be a key site for pathology. In functional dyspepsia, patients with early satiety may have excess eosinophil infiltration, and the mast cell is probably a key player in the irritable syndrome in the small intestine.

Liver X receptors regulate de novo lipogenesis in a tissue-specific manner in C57BL/6 female mice

The liver X receptors (LXRs) play a key role in cholesterol and bile acid metabolism but are also important regulators of glucose metabolism. Recently, LXRs have been proposed as a glucose sensor affecting LXR-dependent gene expression. We challenged wild-type (WT) and LXRαβ(-/-) mice with a normal diet (ND) or a high-carbohydrate diet (HCD). Magnetic resonance imaging showed different fat distribution between WT and LXRαβ(-/-) mice. Surprisingly, gonadal (GL) adipocyte volume decreased on HCD compared with ND in WT mice, whereas it slightly increased in LXRαβ(-/-) mice. Interestingly, insulin-stimulated lipogenesis of isolated GL fat cells was reduced on HCD compared with ND in LXRαβ(-/-) mice, whereas no changes were observed in WT mice. Net de novo lipogenesis (DNL) calculated from Vo(2) and Vco(2) was significantly higher in LXRαβ(-/-) than in WT mice on HCD. Histology of HCD-fed livers showed hepatic steatosis in WT mice but not in LXRαβ(-/-) mice. Glucose tolerance was not different between groups, but insulin sensitivity was decreased by the HCD in WT but not in LXRαβ(-/-) mice. Finally, gene expression analysis of adipose tissue showed induced expression of genes involved in DNL in LXRαβ(-/-) mice compared with WT animals as opposed to the liver, where expression of DNL genes was repressed in LXRαβ(-/-) mice. We thus conclude that absence of LXRs stimulates DNL in adipose tissue, but suppresses DNL in the liver, demonstrating opposite roles of LXR in DNL regulation in these two tissues. These results show tissue-specific regulation of LXR activity, a crucial finding for drug development.

An update in the diagnosis of coeliac disease

Coeliac disease is increasing in prevalence, which is currently estimated at one in 100 of the population and may occur de novo in adults. The diagnosis requires a joint clinicopathological approach; the recommended first-line test is serology with immunoglobulin A (IgA) tissue transglutaminase and IgA endomysial antibodies. These serological tests show high levels of sensitivity and specificity, but biopsy is the gold standard to confirm the diagnosis. It is important that both tests are performed before the introduction of a gluten-free diet. Although the classical histopathology changes of coeliac disease with partial or total villous atrophy are well recognized, the pathology classification of coeliac disease is changing, with recognition that coeliac disease may show minimal pathology (normal architecture and an intraepithelial lymphocyte count/100 enterocytes ≥ 25). This entity is also described as lymphocytic duodenosis, and recommendation of follow-up serology testing is paramount in this condition. Follow-up of patients with coeliac disease is warranted, as normal serology does not predict mucosal recovery. Failure to heal predicts risk of progression to refractory coeliac disease and malignancies. Refractory coeliac disease occurs in 1-2% of patients and this diagnosis requires a combined clinical and histopathology approach with immunocytochemistry.

Topical immunization strategies

Research has yielded an abundance of vaccine candidates against mucosal infections, but only few mucosal vaccines have been registered for human use. Extensive research is being carried out to identify new and safe adjuvants for mucosal immunization, novel delivery systems, including live vectors and reporter molecules for tissue- and cell-specific targeting of vaccine antigens. If these candidates are to reach those in need, several lessons from clinical and field research carried out under resource-poor settings must be considered. These lessons include the need to develop new vaccines that can be administered topically onto the skin or to the mucosa, without needles or expensive delivery devices. Such topical vaccines must be able to protect all age groups at risk, be safe and effective in immunocompromised people, and be able to contain epidemics following complex emergencies. The anatomical compartmentalization of immune responses imposes constraints on the selection of topical route(s) of vaccine administration and on strategies for measuring these responses, especially in young infants. Thus, the selection of any particular route of immunization is critical when designing and formulating vaccines against organ-specific infections.

Gluten-sensitive enteropathy (celiac disease): controversies in diagnosis and classification

CONTEXT

Celiac disease, or gluten-sensitive enteropathy, is a chronic inflammatory disorder of the small intestine characterized by malabsorption after ingestion of gluten in individuals with a certain genetic background. Clinical presentation can vary from full-blown malabsorption to subtle and atypical symptoms. Diagnosis currently relies on clinicopathologic studies including mucosal biopsy, serologic tests, and the effects of a diet free of gluten on the symptoms. Mucosal pathologic features are also variable, ranging from mild abnormalities, including intraepithelial lymphocytosis, to completely flat mucosa. Since patients with minimal histologic lesion of intraepithelial lymphocytosis often present with normal serologic findings, biopsy diagnosis becomes more important for identifying such individuals. Classification of mucosal pathology in gluten-sensitive enteropathy has been a subject of controversy among pathologists and needs to be revised according to the current understanding of the disease.

OBJECTIVES

To highlight the variations in clinical and pathologic presentation of gluten-sensitive enteropathy, to emphasize the importance of small-intestinal biopsy evaluation in the diagnosis, and to propose a new classification of mucosal pathology in gluten-sensitive enteropathy, in an effort to overcome the problems related to the classification systems currently available.

DATA SOURCES

A review of the literature on clinicopathologic features and the morphologic spectrum of gluten-sensitive enteropathy is presented.

CONCLUSIONS

Considering that there are many entities in the differential diagnosis of gluten-sensitive enteropathy, because of the varied clinicopathologic spectrum of the disease, diagnosis depends on good clinicopathologic communication. The classification that is presented in this review is a simple and practical approach to improve clinicopathologic correlation in gluten-sensitive enteropathy.

Body composition of HIV-positive patients with pulmonary tuberculosis: a cross-sectional study in Mwanza, Tanzania

To estimate the weight deficit and body composition of cases of pulmonary TB (PTB), and assess the roles of HIV and the acute-phase response, a cross-sectional study was carried out in Tanzania. Weight, body mass index (BMI), arm muscle area (AMA), arm fat area (AFA) and the serum concentration of the acute-phase protein alpha(1)-antichymotrypsin (serum ACT) were evaluated for each of 532 cases of PTB and 150 'non-TB' controls. On average, the female cases of PTB not only weighed 7.8 kg less but also had BMI that were 3.1-kg/m(2) lower, AMA that were 14.8-cm(2) lower, and AFA that were 7.6-cm(2) lower than those seen in the female subjects without TB. Similarly, on average, the male cases of PTB weighed 7.1 kg less and had BMI that were 2.5-kg/m(2) lower, AMA that were 18.8-cm(2) lower and AFA that were 1.6-cm(2) lower than those seen in the male subjects without TB. Although HIV infection was associated with a 1.7-kg lower weight and a 0.6-kg/m(2) lower BMI (with deficits in both AMA and AFA) among males, it was not associated with any such deficits among the female subjects. Elevated serum ACT was found to be a negative predictor of BMI, AMA and AFA, partially explaining the effects of the PTB but not those of the HIV. There is need for a better understanding of the determinants and effects of loss of fat and lean body mass in HIV-positive tuberculosis.

The Face of Tropical Sprue in 2010

Tropical sprue (TS), although endemic in certain tropical regions of the world, is rarely seen in North America and Europe. However, in this era of globalization and worldwide travel, it is important for all clinicians to be aware of the possibility of TS in patients presenting with nonspecific, persistent gastrointestinal complaints like diarrhea and weight loss. The symptoms and histologic findings of TS can resemble and be confused with those of diseases seen more commonly in nontropical climates like celiac disease and small intestine bacterial overgrowth. Therefore, if the usual causes of persistent diarrhea are ruled out, keeping a high index of suspicion for TS in patients who have a travel history to one of the endemic regions is important.

Lymphocytic disorders of the gastrointestinal tract: a review for the practicing pathologist

Increased numbers of intraepithelial lymphocytes (lymphocytosis) can be found in the esophagus, stomach, small intestine, and colon in a variety of clinical circumstances. This review, directed at practicing pathologists, portrays the normal resident lymphocyte population in the mucosa of each segment of the digestive tract and discusses the different situations that may result in quantitative or qualitative alterations of intraepithelial lymphocytes. Esophageal lymphocytosis has not been fully characterized and its clinical significance, if any, awaits definition. Thus, this diagnosis is presently discouraged. In the stomach, it is particularly important to exclude Helicobacter pylori infection and celiac sprue before diagnosing lymphocytic gastritis. Duodenal lymphocytic infiltrates, inextricably tied with alterations of the villous architecture of the mucosa, are often caused by gluten sensitivity. However, similar morphologic changes may be caused by a vast array of other conditions that must be carefully considered and excluded. Lymphocytic and collagenous colitis are most often unexplained, but their frequent association with autoimmune conditions or certain medications deserve a thorough investigation in each case. Using a combination of histologic and clinical clues, a cause for the intraepithelial lymphocytic infiltration can be identified in many instances. As some of the associated conditions are amenable to effective treatment, the importance of diligently seeking such associations before resorting to a diagnosis of primary lymphocytosis is emphasized.

Small intestinal bacterial overgrowth in systemic sclerosis

OBJECTIVES

The aims of this study were to: (i) determine the prevalence of small intestinal bacterial overgrowth (SIBO) in unselected patients with SSc; (ii) assess both clinical presentation and outcome of SIBO; and (iii) make predictions about which SSc patients are at risk for SIBO.

METHODS

Fifty-one consecutive patients with SSc underwent glucose hydrogen and methane (H(2)/CH(4)) breath test. All SSc patients also completed a questionnaire for intestinal symptoms, and a global symptomatic score (GSS) was calculated. SSc patients with SIBO were given rotating courses of antibiotics (norfloxacin/metronidazole) for 3 months; glucose H(2)/CH(4) breath test was performed at 3-month follow-up.

RESULTS

The prevalence of SIBO was 43.1% in our SSc patients. After logistic regression, we identified the following risk factors for SIBO: presence of diarrhoea and constipation. Interestingly, we observed a marked correlation between values of GSS of digestive symptoms (> or =5) and the presence of SIBO (P = 10(-6)); indeed, both sensitivity and specificity of GSS > or =5 to predict SIBO were as high as 0.909 and 0.862, respectively. Finally, eradication of SIBO was obtained in 52.4% of the SSc patients with a significant improvement of intestinal symptoms.

CONCLUSION

Our study underscores that SIBO often occurs in SSc patients. We further suggest that GSS may be systematically performed in SSc patients; since we found a correlation between GSS of digestive symptoms > or =5 and SIBO, we suggest that glucose H(2)/CH(4) breath test may be performed in the subgroup of SSc patients exhibiting GSS > or =5.

Colony stimulating factor-1 dependence of paneth cell development in the mouse small intestine

BACKGROUND & AIMS

Paneth cells (PCs) secrete defensins and antimicrobial enzymes that contribute to innate immunity against pathogen infections within the mucosa of the small intestine. We examined the role of colony stimulating factor-1 (CSF-1) in PC development.

METHODS

CSF-1-deficient and CSF-1 receptor (CSF-1R)-deficient mice and administration of neutralizing anti-CSF-1R antibody were used to study the requirement of CSF-1 for the development of epithelial cells of the small intestine. CSF-1 transgenic reporter mice and mice that express only the membrane-spanning, cell-surface CSF-1 isoform were used to investigate regulation by systemic versus local CSF-1.

RESULTS

Mice deficient in CSF-1 or CSF-1R had greatly reduced numbers of mature PCs. PCs express the CSF-1R, and administration of anti-CSF-1R antibody to neonatal mice significantly reduced the number of PCs. Analysis of transgenic CSF-1 reporter mice showed that CSF-1-expressing cells are in close proximity to PCs. CSF-1/CSF-1R-deficient mice also had reduced numbers of the proliferating epithelial cell progenitors and lamina propria macrophages. Expression of the membrane-spanning, cell-surface CSF-1 isoform in CSF-1-deficient mice completely rescued the deficiencies of PCs, proliferating progenitors, and lamina propria macrophages.

CONCLUSIONS

These results indicate local regulation by CSF-1 of PC development, either directly, in a juxtacrine/paracrine manner, or indirectly, by lamina propria macrophages. Therefore, CSF-1R hyperstimulation could be involved in hyperproliferative disorders of the small intestine, such as Crohn's disease and ulcerative colitis.

Pancreatic exocrine insufficiency in LXRbeta-/- mice is associated with a reduction in aquaporin-1 expression

Liver X receptors (LXRs) alpha and beta are nuclear oxysterol receptors with a key role in cholesterol, triglyceride, and glucose metabolism. In LXRbeta(-/-) mice on a normal diet, there is a reduction in size of perigonadal fat pad and, on high-fat diet there is resistance to obesity. In the present study, we investigated the reason for the resistance of LXRbeta(-/-) mice to weight gain. In LXRbeta(-/-) mice we found pancreatic exocrine insufficiency with reduced serum levels of amylase and lipase, reduced proteolytic activity in feces, chronic inflammatory infiltration, and, in the ductal epithelium, an increased apoptosis without compensatory proliferation. Electron microscopy revealed ductal dilatation with intraductal laminar structures characteristic of cystic fibrosis. To investigate the relationship between LXRbeta and pancreatic secretion, we studied the expression of LXRbeta and the water channel, aquaporin-1 (AQP1), in the ductal epithelium of the pancreas. In WT mice, ductal epithelial cells expressed LXRbeta in the nuclei and AQP1 on the plasma membrane. In LXRbeta(-/-) mice neither LXRbeta nor AQP1 was detectable. Moreover, in WT mice the LXR agonist (T2320) increased AQP1 gene expression. These data demonstrate that in LXRbeta(-/-) mice dietary resistance to weight gain is caused by pancreatic insufficiency and that LXRbeta regulates pancreatic exocrine secretion through the control of AQP1 expression. Pancreatic exocrine insufficiency is the main cause of malabsorption syndrome responsible for weight loss in adults and growth failure in children. Several genes are known to be involved in the pathogenesis and susceptibility to pancreatic insufficiency. LXRbeta should be included in that list.

Lack of an effect of human immunodeficiency virus coinfection on the pharmacokinetics of entecavir in hepatitis B virus-infected patients

Entecavir is a guanosine nucleoside analogue approved for the treatment of chronic hepatitis B virus (HBV) infection. The impact of human immunodeficiency virus (HIV) coinfection on the pharmacokinetics (PK) of entecavir was examined by nonlinear mixed-effects modeling. Plasma concentration data from HIV- and HBV-coinfected patients were analyzed in conjunction with data from HBV-monoinfected patients, and HIV coinfection was tested as a covariate on oral clearance (CL/F). The estimated population averages of intercompartmental clearance and the volumes of distribution in the central and peripheral compartments obtained with a 1-mg dose were 34.2 liters/h (interindividual variability, 30.2%), 115 liters (interindividual variability, 39.2%), and 1,830 liters (interindividual variability, 74%), respectively. CL/F was found to be a function of creatinine clearance, but HIV confection did not show any effect on CL/F. The geometric mean (GM) of individual Bayesian estimates of the steady-state area under the concentration-time curve following 1-mg daily doses were 39.3 and 38.8 ng x h/ml in HIV- and HBV-coinfected and HBV-monoinfected patients, respectively. The adjusted GM ratio (1.01; 90% confidence interval, 0.91 to 1.12) was within the bioequivalence criteria boundary (0.80 to 1.25). In conclusion, the proposed model adequately described the entecavir PK in HBV- and HIV-coinfected patients and HBV-monoinfected patients, and the entecavir exposures were comparable in the two patient populations.

Small intestinal bacterial overgrowth in patients suffering from scleroderma: clinical effectiveness of its eradication

OBJECTIVES

After the skin, the gastrointestinal tract is the second most common target of systemic sclerosis (SSc).

AIM

Our aims were to investigate orocecal transit time (OCTT) and the presence of small intestinal bacterial overgrowth (SIBO) in SSc as a cause of intestinal symptoms.

METHODS

Fifty-five SSc patients and 60 healthy controls, sex and age matched, entered the study. Enrolled subjects completed a questionnaire for intestinal symptoms and a global symptomatic score (GSS) was calculated. OCTT and the presence of SIBO were assessed by a lactulose breath test (LBT). Patients with SIBO were treated with rifaximin 1,200 mg/day for 10 days. Finally, a second questionnaire and LBT were performed 1 month after the end of therapy.

RESULTS

The prevalence of SIBO was higher in SSc patients compared with controls (30/54 vs 4/60, respectively, P < 0.001). OCTT was significantly slower in SSc patients compared with controls (150 min, 25-75th percentile 142.5-165 vs 105 min, 25-75th percentile 90-135, respectively, P < 0.001). In patients with SIBO, the median GSS score was 8 (25-75th percentile 3.25-10.75). Eradication of SIBO was achieved in 73.3% of patients, with a significant reduction of symptoms in 72.7% of them (GSS score 2, 25-75th percentile 1-3, P < 0.05).

CONCLUSIONS

These data suggest that SIBO occurs more frequently in SSc patients than in controls. Intestinal symptoms in these patients may be related to this syndrome and its eradication seems useful to improve clinical features. OCTT is significantly delayed in SSc patients, suggesting an impairment of intestinal motility, a further risk factor for the development of SIBO.