Glutamine supplementation as a novel metabolic therapeutic strategy for LIG3-dependent chronic intestinal pseudo-obstruction.

BACKGROUND AND AIMS: We recently identified a recessive syndrome due to LIG3 mutations in patients with chronic intestinal pseudo-obstruction, leukoencephalopathy and neurogenic bladder. LIG3 mutations affect mitochondrial DNA (mtDNA) maintenance, leading to defective energy production. We aimed at identifying altered molecular pathways and develop possible targeted treatments to revert / ameliorate the cellular energy impairment. METHODS: Whole transcriptome analysis was performed on patients' derived fibroblasts total RNA and controls. Mitochondrial function, mitophagy, L-Glutamine (L-Gln) supplementation effects were analyzed by live cell analysis, immunostaining and western blot. Patients were treated with Dipeptiven according to standard protocols. Patients' symptoms were analyzed by the Gastrointestinal Symptom Rating Scale questionnaire. RESULTS: We identified deregulated transcripts in mutant fibroblasts vs. controls, including overexpression of genes involved in extracellular matrix development and remodeling and mitochondrial functions. Gut biopsies of LIG3-mutant patients documented collagen and elastic fiber accumulation. Mutant fibroblasts exhibited impaired mitochondrial mitophagy indicative of dysfunctional turnover and altered Ca2+ homeostasis. L-Gln supplementation (6 mM), previously shown to increase mtDNA-defective cell survival, improved growth rate and ATP production in LIG3-mutant fibroblasts. These data led us to provide parenterally a dipeptide containing L-Gln to three siblings carrying biallelic LIG3 mutations. Compared to baseline, gastrointestinal and extra-gastrointestinal symptoms significantly improved after 8 months of treatment. CONCLUSIONS: LIG3 deficiency leads to mitochondrial dysfunction. High levels L-Gln supplementation was beneficial in LIG3-mutant cells and improved symptom severity without noticeable side effects. Our results provide a proof-of-concept to design ad hoc clinical trials with L-Gln in LIG3-mutant patients.

Structural Variants at the LMNB1 Locus: Deciphering Pathomechanisms in Autosomal Dominant Adult-Onset Demyelinating Leukodystrophy.

OBJECTIVES: We aimed to elucidate the pathogenic mechanisms underlying autosomal dominant adult-onset demyelinating leukodystrophy (ADLD), and to understand the genotype/phenotype correlation of structural variants (SVs) in the LMNB1 locus. BACKGROUND: Since the discovery of 3D genome architectures and topologically associating domains (TADs), new pathomechanisms have been postulated for SVs, regardless of gene dosage changes. ADLD is a rare genetic disease associated with duplications (classical ADLD) or noncoding deletions (atypical ADLD) in the LMNB1 locus. METHODS: High-throughput chromosome conformation capture, RNA sequencing, histopathological analyses of postmortem brain tissues, and clinical and neuroradiological investigations were performed. RESULTS: We collected data from >20 families worldwide carrying SVs in the LMNB1 locus and reported strong clinical variability, even among patients carrying duplications of the entire LMNB1 gene, ranging from classical and atypical ADLD to asymptomatic carriers. We showed that patients with classic ADLD always carried intra-TAD duplications, resulting in a simple gene dose gain. Atypical ADLD was caused by LMNB1 forebrain-specific misexpression due to inter-TAD deletions or duplications. The inter-TAD duplication, which extends centromerically and crosses the 2 TAD boundaries, did not cause ADLD. Our results provide evidence that astrocytes are key players in ADLD pathology. INTERPRETATION: Our study sheds light on the 3D genome and TAD structural changes associated with SVs in the LMNB1 locus, and shows that a duplication encompassing LMNB1 is not sufficient per se to diagnose ADLD, thereby strongly affecting genetic counseling. Our study supports breaking TADs as an emerging pathogenic mechanism that should be considered when studying brain diseases. ANN NEUROL 2024.

Vasoactive Intestinal Polypeptide Plays a Key Role in the Microbial-Neuroimmune Control of Intestinal Motility.

BACKGROUND & AIMS: Although chronic diarrhea and constipation are common, the treatment is symptomatic because their pathophysiology is poorly understood. Accumulating evidence suggests that the microbiota modulates gut function, but the underlying mechanisms are unknown. We therefore investigated the pathways by which microbiota modulates gastrointestinal motility in different sections of the alimentary tract. METHODS: Gastric emptying, intestinal transit, muscle contractility, acetylcholine release, gene expression, and vasoactive intestinal polypeptide (VIP) immunoreactivity were assessed in wild-type and Myd88-/-Trif-/- mice in germ-free, gnotobiotic, and specific pathogen-free conditions. Effects of transient colonization and antimicrobials as well as immune cell blockade were investigated. VIP levels were assessed in human full-thickness biopsies by Western blot. RESULTS: Germ-free mice had similar gastric emptying but slower intestinal transit compared with specific pathogen-free mice or mice monocolonized with Lactobacillus rhamnosus or Escherichia coli, the latter having stronger effects. Although muscle contractility was unaffected, its neural control was modulated by microbiota by up-regulating jejunal VIP, which co-localized with and controlled cholinergic nerve function. This process was responsive to changes in the microbial composition and load and mediated through toll-like receptor signaling, with enteric glia cells playing a key role. Jejunal VIP was lower in patients with chronic intestinal pseudo-obstruction compared with control subjects. CONCLUSIONS: Microbial control of gastrointestinal motility is both region- and bacteria-specific; it reacts to environmental changes and is mediated by innate immunity-neural system interactions. By regulating cholinergic nerves, small intestinal VIP plays a key role in this process, thus providing a new therapeutic target for patients with motility disorders.

Serum zonulin levels are increased in Alzheimer's disease but not in vascular dementia.

BACKGROUND: Zonulin is involved in the integrity and functioning of both intestinal-epithelial barrier and blood-brain barrier (BBB) by regulating tight junction molecular assembly. AIM: Since changes in microbiota and BBB may play a role in neurodegenerative disorders, we aimed to determine whether serum zonulin levels change in older patients affected by different types of dementia or mild cognitive impairment (MCI). METHODS: We evaluated serum zonulin levels in patients with late-onset AD (LOAD), vascular dementia (VAD), MIXED (AD + VAD) dementia, amnestic MCI, and in healthy controls. RESULTS: Compared with controls, serum zonulin increased in LOAD, MIXED dementia, and aMCI but not in VAD, independent of potential confounders (ANCOVA p = 0.01; LOAD vs controls, p = 0.01; MIXED vs. controls, p = 0.003; aMCI vs. controls, p = 0.04). Notably, aMCI converting to dementia showed significantly higher levels of zonulin compared with stable aMCI (p = 0.04). Serum zonulin inversely correlated with the standardized Mini-Mental State Examination (MMSE) score (p < 0.05), regardless of potential confounders. DISCUSSION: We found increased serum zonulin levels in patients with aMCI, LOAD and MIXED dementia, but not in VAD; moreover, zonulin levels were higher in aMCI converting to AD compared with stable ones. CONCLUSIONS: Our findings suggest that a dysregulation of intestinal-epithelial barrier and/or BBB may be an early specific event in AD-related neurodegeneration.

Microbiota-Gut-Brain Axis in Neurological Disorders: From Leaky Barriers Microanatomical Changes to Biochemical Processes.

BACKGROUND: The gastrointestinal tract and the central nervous system are distinct because of evident morpho-functional features. Nonetheless, evidence indicates that these systems are bidirectionally connected through the gut-brain axis, defined as the signaling that takes place between the gastrointestinal tract and central nervous system, which plays in concert with the gut microbiota, i.e., the myriad of microorganisms residing in the lumen of the human intestine. In particular, it has been described that gut microbiota abnormalities, referred to as dysbiosis, may affect both central nervous system development and physiology. OBJECTIVE: Starting from the possible mechanisms through which gut microbiota variations were found to impact several central nervous system disorders, including Autism Spectrum Disorder and Alzheimer's Disease, we will focus on intriguing, although poorly investigated, aspects such as the epithelial and vascular barrier integrity. Indeed, several studies suggest a pivotal role of gut microbiota in maintaining the efficiency of both the intestinal barrier and blood-brain barrier. In particular, we report evidence indicating an impact of gut microbiota on intestinal barrier and blood-brain barrier homeostasis and discuss the differences and the similarities between the two barriers. Moreover, to stimulate further research, we review various tests and biochemical markers that can be used to assess intestinal and blood-brain barrier permeability. CONCLUSION: We suggest that the evaluation of intestinal and blood-brain barrier permeability in neurological patients may not only help to better understand central nervous system disorders but also pave the way for finding new molecular targets to treat patients with neurological impairment.

Anatomical Laser Microdissection of the Ileum Reveals mtDNA Depletion Recovery in A Mitochondrial Neuro-Gastrointestinal Encephalomyopathy (MNGIE) Patient Receiving Liver Transplant.

mitochondrial neuro-gastrointestinal encephalomyopathy (MNGIE) is a rare genetic disorder characterized by thymidine phosphorylase (TP) enzyme defect. The absence of TP activity induces the imbalance of mitochondrial nucleotide pool, leading to impaired mitochondrial DNA (mtDNA) replication and depletion. Since mtDNA is required to ensure oxidative phosphorylation, metabolically active tissues may not achieve sufficient energy production. The only effective life-saving approach in MNGIE has been the permanent replacement of TP via allogeneic hematopoietic stem cell or liver transplantation. However, the follow-up of transplanted patients showed that gut tissue changes do not revert and fatal complications, such as massive gastrointestinal bleeding, can occur. The purpose of this study was to clarify whether the reintroduction of TP after transplant can recover mtDNA copy number in a normal range. Using laser capture microdissection and droplet-digital-PCR, we assessed the mtDNA copy number in each layer of full-thickness ileal samples of a naive MNGIE cohort vs. controls and in a patient pre- and post-TP replacement. The treatment led to a significant recovery of gut tissue mtDNA amount, thus showing its efficacy. Our results indicate that a timely TP replacement is needed to maximize therapeutic success before irreversible degenerative tissue changes occur in MNGIE.

Inflammatory bowel disease as a new risk factor for dementia.

The prognostic impact of inflammatory bowel disease (IBD), chronic inflammatory conditions consisting of ulcerative colitis (UC), and Crohn's disease (CD) on the risk of dementia has been poorly investigated. We evaluated the risk of dementia in IBD patients by a systematic review and meta-analysis of the available data. Three studies, enrolling 121.827 patients [14.839 IBD (12.1%) and 106.961 (87.7%) controls, respectively] were included in the analysis. Of these, 57.7% (n = 8.571) had UC, while 42.2% (n = 6268) had CD. The mean follow-up period was 21.3 years. A random effect model revealed an aHR of 1.52 (95% CI 1.04-2.020, p = 0.01; I2 = 91.1%) for dementia in IBD patients. Sensitivity analysis confirmed yielded results. Subjects having a CD showed an aHR for dementia of 1.48 (95% CI 1.07-2.03, p = 0.001, I2 = 68.9%), while the risk among those with a history of UC did not reach the statistical significance (aHR: 1.47, 95% CI 0.95-2.82, p = 0.81, I2 = 89.9%). IBD males had an increased risk of dementia compared to women. IBD patients and in particular those with CD have an increased risk of dementia in the long-term period.

Biallelic variants in LIG3 cause a novel mitochondrial neurogastrointestinal encephalomyopathy.

Abnormal gut motility is a feature of several mitochondrial encephalomyopathies, and mutations in genes such as TYMP and POLG, have been linked to these rare diseases. The human genome encodes three DNA ligases, of which only one, ligase III (LIG3), has a mitochondrial splice variant and is crucial for mitochondrial health. We investigated the effect of reduced LIG3 activity and resulting mitochondrial dysfunction in seven patients from three independent families, who showed the common occurrence of gut dysmotility and neurological manifestations reminiscent of mitochondrial neurogastrointestinal encephalomyopathy. DNA from these patients was subjected to whole exome sequencing. In all patients, compound heterozygous variants in a new disease gene, LIG3, were identified. All variants were predicted to have a damaging effect on the protein. The LIG3 gene encodes the only mitochondrial DNA (mtDNA) ligase and therefore plays a pivotal role in mtDNA repair and replication. In vitro assays in patient-derived cells showed a decrease in LIG3 protein levels and ligase activity. We demonstrated that the LIG3 gene defects affect mtDNA maintenance, leading to mtDNA depletion without the accumulation of multiple deletions as observed in other mitochondrial disorders. This mitochondrial dysfunction is likely to cause the phenotypes observed in these patients. The most prominent and consistent clinical signs were severe gut dysmotility and neurological abnormalities, including leukoencephalopathy, epilepsy, migraine, stroke-like episodes, and neurogenic bladder. A decrease in the number of myenteric neurons, and increased fibrosis and elastin levels were the most prominent changes in the gut. Cytochrome c oxidase (COX) deficient fibres in skeletal muscle were also observed. Disruption of lig3 in zebrafish reproduced the brain alterations and impaired gut transit in vivo. In conclusion, we identified variants in the LIG3 gene that result in a mitochondrial disease characterized by predominant gut dysmotility, encephalopathy, and neuromuscular abnormalities.

Evidence of enteric angiopathy and neuromuscular hypoxia in patients with mitochondrial neurogastrointestinal encephalomyopathy.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by thymidine phosphorylase (TP) enzyme defect. As gastrointestinal changes do not revert in patients undergone TP replacement therapy, one can postulate that other unexplored mechanisms contribute to MNGIE pathophysiology. Hence, we focused on the local TP angiogenic potential that has never been considered in MNGIE. In this study, we investigated the enteric submucosal microvasculature and the effect of hypoxia on fibrosis and enteric neurons density in jejunal full-thickness biopsies collected from patients with MNGIE. Orcein staining was used to count blood vessels based on their size. Fibrosis was assessed using the Sirius Red and Fast Green method. Hypoxia and neoangiogenesis were determined via hypoxia-inducible-factor-1α (HIF-1α) and vascular endothelial cell growth factor (VEGF) protein expression, respectively. Neuron-specific enolase was used to label enteric neurons. Compared with controls, patients with MNGIE showed a decreased area of vascular tissue, but a twofold increase of submucosal vessels/mm2 with increased small size and decreased medium and large size vessels. VEGF positive vessels, fibrosis index, and HIF-1α protein expression were increased, whereas there was a diminished thickness of the longitudinal muscle layer with an increased interganglionic distance and reduced number of myenteric neurons. We demonstrated the occurrence of an angiopathy in the GI tract of patients with MNGIE. Neoangiogenetic changes, as detected by the abundance of small size vessels in the jejunal submucosa, along with hypoxia provide a morphological basis to explain neuromuscular alterations, vasculature breakdown, and ischemic abnormalities in MNGIE.NEW & NOTEWORTHY Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is characterized by a genetically driven defect of thymidine phosphorylase, a multitask enzyme playing a role also in angiogenesis. Indeed, major gastrointestinal bleedings are life-threatening complications of MNGIE. Thus, we focused on jejunal submucosal vasculature and showed intestinal microangiopathy as a novel feature occurring in this disease. Notably, vascular changes were associated with neuromuscular abnormalities, which may explain gut dysfunction and help to develop future therapeutic approaches in MNGIE.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): Position paper on diagnosis, prognosis, and treatment by the MNGIE International Network.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by TYMP mutations and thymidine phosphorylase (TP) deficiency. Thymidine and deoxyuridine accumulate impairing the mitochondrial DNA maintenance and integrity. Clinically, patients show severe and progressive gastrointestinal and neurological manifestations. The onset typically occurs in the second decade of life and mean age at death is 37 years. Signs and symptoms of MNGIE are heterogeneous and confirmatory diagnostic tests are not routinely performed by most laboratories, accounting for common misdiagnosis. Factors predictive of progression and appropriate tests for monitoring are still undefined. Several treatment options showed promising results in restoring the biochemical imbalance of MNGIE. The lack of controlled studies with appropriate follow-up accounts for the limited evidence informing diagnostic and therapeutic choices. The International Consensus Conference (ICC) on MNGIE, held in Bologna, Italy, on 30 March to 31 March 2019, aimed at an evidence-based consensus on diagnosis, prognosis, and treatment of MNGIE among experts, patients, caregivers and other stakeholders involved in caring the condition. The conference was conducted according to the National Institute of Health Consensus Conference methodology. A consensus development panel formulated a set of statements and proposed a research agenda. Specifically, the ICC produced recommendations on: (a) diagnostic pathway; (b) prognosis and the main predictors of disease progression; (c) efficacy and safety of treatments; and (f) research priorities on diagnosis, prognosis, and treatment. The Bologna ICC on diagnosis, management and treatment of MNGIE provided evidence-based guidance for clinicians incorporating patients' values and preferences.

Liver transplantation in mitochondrial neurogastrointestinal encephalomyopathy (MNGIE): clinical long-term follow-up and pathogenic implications.

We report the longest follow-up of clinical and biochemical features of two previously reported adult mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) patients treated with liver transplantation (LT), adding information on a third, recently transplanted, patient. All three patients overcame the early post-operative period and tolerated immunosuppressive therapy. Plasma nucleoside levels dramatically decreased, with evidence of clinical improvement of ambulation and neuropathy. Conversely, other features of MNGIE, as gastrointestinal dysmotility, low weight, ophthalmoparesis, and leukoencephalopathy were essentially unchanged. A similar picture characterized two patients treated with allogenic hematopoietic stem cell transplantation (AHSCT). In conclusion, LT promptly and stably normalizes nucleoside imbalance in MNGIE, stabilizing or improving some clinical parameters with marginal periprocedural mortality rate as compared to AHSCT. Nevertheless, restoring thymidine phosphorylase (TP) activity, achieved by both LT and AHSCT, does not allow a full clinical recovery, probably due to consolidated cellular damage and/or incomplete enzymatic tissue replacement.

Mast cell-nerve interactions correlate with bloating and abdominal pain severity in patients with non-celiac gluten / wheat sensitivity.

BACKGROUND: Gastrointestinal (GI) and extra-GI symptoms/manifestations represent key clinical features of patients with non-celiac gluten/wheat sensitivity (NCG/WS). This study aimed to investigate neuro-immune (focusing on mast cells, MCs) interactions in the duodenal submucosa of patients with NCG/WS. METHODS: Submucosal whole mounts from duodenal biopsies of 34 patients with self-reported NCG/WS, 28 with celiac disease (CD), 13 with functional dyspepsia (FD), and 24 healthy controls (HC) were analyzed by immunohistochemistry. Quantitative data on neuronal and MCs density and the percentage of MCs in close vicinity to nerves were obtained, and correlations among neurons, MC density and MC-nerve distance (D), and symptoms were assessed in the three groups. KEY RESULTS: The number of submucosal neurons was not different among groups. In NCG/WS, MC density was not different from HC, while it was slightly increased vs. CD (P = .07) and significantly decreased vs. FD (P < .05). The percentage of MCs close to nerves (D < 15 µm) was similarly increased in all three pathological groups vs. HC (P < .001). In NCG/WS, MC infiltration correlated with bloating (P = .001) and abdominal pain severity (P = .03) and the percentage of MCs in proximity to neurons correlated with the number of GI symptoms (D < 5 µm; P = .05), bloating and abdominal pain severity (D < 15um; P = .01). CONCLUSIONS AND INFERENCES: Submucosal MC infiltration and the close (within 15 µm) MC-to-nerve proximity in the duodenum of NCG/WS patients are features providing a histopathological basis to better understand GI symptoms in this condition.

Enteric neuron density correlates with clinical features of severe gut dysmotility.

Gastrointestinal (GI) symptoms can originate from severe dysmotility due to enteric neuropathies. Current methods used to demonstrate enteric neuropathies are based mainly on classic qualitative histopathological/immunohistochemical evaluation. This study was designed to identify an objective morphometric method for paraffin-embedded tissue samples to quantify the interganglionic distance between neighboring myenteric ganglia immunoreactive for neuron-specific enolase, as well as the number of myenteric and submucosal neuronal cell bodies/ganglion in jejunal specimens of patients with severe GI dysmotility. Jejunal full-thickness biopsies were collected from 32 patients (22 females; 16-77 yr) with well-characterized severe dysmotility and 8 controls (4 females; 47-73 yr). A symptom questionnaire was filled before surgery. Mann-Whitney U test, Kruskal-Wallis coupled with Dunn's posttest and nonparametric linear regression tests were used for analyzing morphometric data and clinical correlations, respectively. Compared with controls, patients with severe dysmotility exhibited a significant increase in myenteric interganglionic distance (P = 0.0005) along with a decrease in the number of myenteric (P < 0.00001) and submucosal (P < 0.0004) neurons. A 50% reduction in the number of submucosal and myenteric neurons correlated with an increased interganglionic distance and severity of dysmotility. Our study proposes a relatively simple tool that can be applied for quantitative evaluation of paraffin sections from patients with severe dysmotility. The finding of an increased interganglionic distance may aid diagnosis and limit the direct quantitative analysis of neurons per ganglion in patients with an interganglionic distance within the control range.NEW & NOTEWORTHY Enteric neuropathies are challenging conditions characterized by a severe impairment of gut physiology, including motility. An accurate, unambiguous assessment of enteric neurons provided by quantitative analysis of routine paraffin sections may help to define neuropathy-related gut dysmotility. We showed that patients with severe gut dysmotility exhibited an increased interganglionic distance associated with a decreased number of myenteric and submucosal neurons, which correlated with symptoms and clinical manifestations of deranged intestinal motility.

Gut epithelial and vascular barrier abnormalities in patients with chronic intestinal pseudo-obstruction.

BACKGROUND: Chronic intestinal pseudo-obstruction (CIPO) is a rare condition due to severe impairment of gut motility responsible for recurrent subocclusive episodes. Although neuromuscular-glial-ICC abnormalities represent the main pathogenetic mechanism, the pathophysiology of CIPO remains poorly understood. Intestinal epithelial and vascular endothelial barrier (IEVB) abnormalities can contribute to neuroepithelial changes by allowing passage of harmful substances. METHODS: To test retrospectively whether IEVB defects occur in patients with CIPO, we measured the jejunal protein expression of the major tight junction (TJ) components. CIPO patients were subdivided according to gut neuromuscular histopathology: apparently normal (AN); with inflammation (INF); or with degenerative alterations (DEG). The presence of occludin/claudin oligomers (index of TJ assembly), the amount of occludin, claudin-4, and zonula occludens-1 (ZO-1), and the expression of vasoactive intestinal polypeptide (VIP) and glial fibrillary acidic protein (GFAP) immunoreactivities were evaluated on jejunal full-thickness biopsies using Western blot. KEY RESULTS: Oligomers were absent in the 73% of CIPO. Total occludin decreased in CIPO with AN and INF changes. Claudin-4 was upregulated in CIPO with INF and DEG features. ZO-1 and VIP expression decreased selectively in DEG group. GFAP increased in CIPO regardless the histopathological phenotype. CONCLUSIONS & INFERENCES: The absence of oligomers demonstrated in our study suggests that IEBV is altered in CIPO. The mechanism leading to oligomerization is occludin-dependent in AN and INF, whereas is ZO-1-dependent in DEG. Our study provides support to IEVB abnormalities contributing to CIPO clinical and histopathological features.

Liver transplantation for mitochondrial neurogastrointestinal encephalomyopathy.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a fatal, recessive disease caused by mutations in the gene encoding thymidine phosphorylase, leading to reduced enzymatic activity, toxic nucleoside accumulation, and secondary mitochondrial DNA damage. Thymidine phosphorylase replacement has been achieved by allogeneic hematopoietic stem cell transplantation, a procedure hampered by high mortality. Based on high thymidine phosphorylase expression in the liver, a 25-year-old severely affected patient underwent liver transplantation. Serum levels of toxic nucleosides rapidly normalized. At 400 days of follow-up, the patient's clinical conditions are stable. We propose liver transplantation as a new therapy for MNGIE. Ann Neurol 2016;80:448-455.

Dietary Triggers in Irritable Bowel Syndrome: Is There a Role for Gluten?

A tight link exists between dietary factors and irritable bowel syndrome (IBS), one of the most common functional syndromes, characterized by abdominal pain/discomfort, bloating and alternating bowel habits. Amongst the variety of foods potentially evoking "food sensitivity", gluten and other wheat proteins including amylase trypsin inhibitors represent the culprits that recently have drawn the attention of the scientific community. Therefore, a newly emerging condition termed non-celiac gluten sensitivity (NCGS) or nonceliac wheat sensitivity (NCWS) is now well established in the clinical practice. Notably, patients with NCGS/NCWS have symptoms that mimic those present in IBS. The mechanisms by which gluten or other wheat proteins trigger symptoms are poorly understood and the lack of specific biomarkers hampers diagnosis of this condition. The present review aimed at providing an update to physicians and scientists regarding the following main topics: the experimental and clinical evidence on the role of gluten/wheat in IBS; how to diagnose patients with functional symptoms attributable to gluten/wheat sensitivity; the importance of double-blind placebo controlled cross-over trials as confirmatory assays of gluten/wheat sensitivity; and finally, dietary measures for gluten/wheat sensitive patients. The analysis of current evidence proposes that gluten/wheat sensitivity can indeed represent a subset of the broad spectrum of patients with a clinical presentation of IBS.

Seronegative celiac disease: Shedding light on an obscure clinical entity.

BACKGROUND: Although serological tests are useful for identifying celiac disease, it is well established that a minority of celiacs are seronegative. AIM: To define the prevalence and features of seronegative compared to seropositive celiac disease, and to establish whether celiac disease is a common cause of seronegative villous atrophy. METHODS: Starting from 810 celiac disease diagnoses, seronegative patients were retrospectively characterized for clinical, histological and laboratory findings. RESULTS: Of the 810 patients, fourteen fulfilled the diagnostic criteria for seronegative celiac disease based on antibody negativity, villous atrophy, HLA-DQ2/-DQ8 positivity and clinical/histological improvement after gluten free diet. Compared to seropositive, seronegative celiac disease showed a significantly higher median age at diagnosis and a higher prevalence of classical phenotype (i.e., malabsorption), autoimmune disorders and severe villous atrophy. The most frequent diagnosis in the 31 cases with seronegative flat mucosa was celiac disease (45%), whereas other diagnoses were Giardiasis (20%), common variable immunodeficiency (16%) and autoimmune enteropathy (10%). CONCLUSIONS: Although rare seronegative celiac disease can be regarded as the most frequent cause of seronegative villous atrophy being characterized by a high median age at diagnosis; a close association with malabsorption and flat mucosa; and a high prevalence of autoimmune disorders.

Autoimmune enteropathy: not all flat mucosa mean coeliac disease.

A 62-year-old woman complaining of severe malabsorption was diagnosed with celiac disease based on the findings of flat, small intestinal mucosa and HLA-DQ2 positivity, although celiac serology was negative. This diagnosis was questioned due to the lack of clinical and histological improvement after a long period of strict gluten-free diet. The detection of enterocyte autoantibodies guided to the correct diagnosis of autoimmune enteropathy, leading to a complete recovery of the patient following an appropriate immunosuppressive treatment. Autoimmune enteropathy should be considered in the differential diagnosis of malabsorption with severe villous atrophy, including those cases with negative celiac-related serology.

ITA-MNGIE: an Italian regional and national survey for mitochondrial neuro-gastro-intestinal encephalomyopathy.

Mitochondrial neuro-gastro-intestinal encephalomyopathy (MNGIE) is a rare and unavoidably fatal disease due to mutations in thymidine phosphorylase (TP). Clinically it is characterized by gastrointestinal dysfunction, malnutrition/cachexia and neurological manifestations. MNGIE diagnosis remains a challenge mainly because of the complexity and rarity of the disease. Thus, our purposes were to promote a better knowledge of the disease in Emilia-Romagna region (ERR) by creating an accurate and dedicated network; to establish the minimal prevalence of MNGIE in Italy starting from ERR. Blood TP activity level was used as screening test to direct candidates to complete diagnostic work-up. During the study period of 1 year, only 10/71 units of ERR recruited 14 candidates. Their screening did not show TP activity changes. An Italian patient not resident in ERR was actually proved to have MNGIE. At the end of study in Italy there were nine cases of MNGIE; thus, the Italian prevalence of the disease is ~0.15/1,000,000 as a gross estimation. Our study confirms that MNGIE diagnosis is a difficult process which reflects the rarity of the disease and, as a result, a low level of awareness among specialists and physicians. Having available novel therapeutic options (e.g., allogenic hematopoietic stem cell transplantation and, more recently, liver transplantation) and an easy screening test, an early diagnosis should be sought before tissue damage occurs irreversibly.