A Hereditary Enteropathy Caused by Mutations in the SLCO2A1 Gene, Encoding a Prostaglandin Transporter

Pathogenesis of chronic enteropathy associated with the SLCO2A1 gene: Hypotheses and conundrums

Chronic enteropathy associated with the SLCO2A1 gene (CEAS) is a complex gastroenterological condition characterized by multiple ulcers in the small intestine with chronic bleeding and protein loss. This review explores the potential mechanisms underlying the pathogenesis of CEAS, focusing on the role of SLCO2A1-encoded prostaglandin transporter OATP2A1 and its impact on prostaglandin E2 (PGE2) levels. Studies have suggested that elevated PGE2 levels contribute to mucosal damage, inflammation, and disruption of the intestinal barrier. The effects of PGE2 on macrophage activation and Maxi-Cl channel functionality, as well as its interaction with nonsteroidal anti-inflammatory drugs play crucial roles in the progression of CEAS. Understanding the balance between its protective and pro-inflammatory effects and the complex interactions within the gastrointestinal tract can shed light on potential therapeutic targets for CEAS and guide the development of novel, targeted therapies.

Clinical and genetic characteristics of Chinese patients diagnosed with chronic enteropathy associated with SLCO2A1 gene

BACKGROUND AND AIMS

Chronic enteropathy associated with SLCO2A1 gene is a rare intestinal disease caused by loss-of-function SLCO2A1 mutations, with clinical and genetic characteristics remaining largely unknown, especially in Chinese patients. This study aims to reveal clinical and genetic features of Chinese CEAS patients, highlighting the previously unreported or unemphasized characteristics.

METHODS

We enrolled 12 Chinese patients with chronic enteropathy associated with SLCO2A1 gene admitted to Peking Union Medical College Hospital from January 2018 to December 2022. Clinical and genetic data of these patients were collected and analyzed.

RESULTS

58.3% of patients were male, who also had primary hypertrophic osteoarthropathy, whereas female patients did not have primary hypertrophic osteoarthropathy. Apart from common symptoms associated with anemia and hypoalbuminemia, abdominal pain, ileus, diarrhea, and hematochezia were present. 4 of the 5 female patients had early-onset amenorrhea, though the causal relationship remained to be clarified. Endoscopy and computed tomography enterography revealed that lesions can occur in any part of the digestive tract, most commonly in the ileum. Pathology showed multiple superficial ulcers with adjacent vascular dilatation, and loss of SLCO2A1 expression, particularly in gastrointestinal vascular endothelial cells. Genetic analysis confirmed SLCO2A1 mutations in all patients and identified 11 new SLCO2A1 variants for CEAS.

CONCLUSIONS

This study reports new clinical, pathological, and genetic findings in 12 Chinese patients with chronic enteropathy associated with SLCO2A1 gene. This study provides insights into the pathogenesis of this disease. However, studies with larger sample sizes and more in-depth mechanism research are still required.

Label-free detection of prostaglandin transporter (SLCO2A1) function and inhibition: insights by wound healing and TRACT assays

The prostaglandin transporter (PGT, SLCO2A1) mediates transport of prostanoids (a.o. prostaglandin E2 (PGE2)) into cells and thereby promotes their degradation. Overexpression of PGT leads to low extracellular PGE2 levels and has been linked to impaired wound healing of diabetic foot ulcers. Inhibition of PGT could thus be beneficial, however, no PGT inhibitors are currently on the market and drug discovery efforts are hampered by lack of high-through screening assays for this transporter. Here we report on a label-free impedance-based assay for PGT that measures transport activity through receptor activation (TRACT) utilizing prostaglandin E2 receptor subtype EP3 and EP4 that are activated by PGE2. We found that induction of PGT expression on HEK293-JumpIn-SLCO2A1 cells that also express EP3 and EP4 leads to an over 10-fold reduction in agonistic potency of PGE2. PGE2 potency could be recovered upon inhibition of PGT-mediated PGE2 uptake with PGT inhibitors olmesartan and T26A, the potency of which could be established as well. Moreover, the TRACT assay enabled the assessment of transport function of PGT natural variants. Lastly, HUVEC cells endogenously expressing prostanoid receptors and PGT were exploited to study wound healing properties of PGE2 and T26A in real-time using a novel impedance-based scratch-induced wound healing assay. These novel impedance-based assays will advance PGT drug discovery efforts and pave the way for the development of PGT-based therapies.

First case report of dichorionic diamniotic twins with chronic enteropathy associated with the SLCO2A1 gene

We report the case of twins diagnosed with chronic enteropathy associated with the SLCO2A1 gene (CEAS) based on characteristic ulcer findings, which required 8 years to diagnose. Both twins had similar symptoms, including anemia and growth failure but the gastrointestinal tract was not evaluated initially because of mild symptoms that were considered consistent with psychological etiology. The endoscopic findings of the firstborn child showed spiral ulcer scars and pseudodiverticulum formation without Helicobacter pylori infection or eosinophilic infiltration in the duodenum. Since the twins presented with ulcers of an unknown cause simultaneously and the first-born child had a spiral ulcer, CEAS was suspected. Genetic analysis and high levels of prostaglandin E major urinary metabolites in the urine led to a definitive diagnosis of CEAS.

Genotype and phenotype characterization of primary hypertrophic osteoarthropathy type 2 and chronic enteropathy associated with SLCO2A1: Report of two cases and literature review

Autosomal recessive type 2 primary hypertrophic osteoarthropathy (PHOAR2) and chronic enteropathy associated with SLCO2A1 (CEAS) are two entities caused by pathogenic variants (PVs) in the SLCO2A1 gene that can coexist or occur independently from one another. We report two cases of PHOAR2 in Mexico with concomitant CEAS and conducted a review of the literature of the reported cases of PHOAR2 and/or CEAS to analyze the relationship between their genotype and phenotype presentation. The patients from our Institution with classical PHOAR2 phenotype and CEAS, harbored SLCO2A1 c.547G > A and c.1768del variants. We reviewed 232 cases, of which 86.6% were of Asian origin, and identified 109 different variants in SLCO2A1. Intron 7, exon 13, and exon 4 were predominantly affected. The two most common PVs were c.940 + 1G > A and c.1807C > T. We found a statistically significant association between SLCO2A1 variants located in intron 7, exons 12, and 13 and the development of CEAS. Missense variants were more frequent in isolated PHOAR2, while a greater proportion of protein-truncating variants (PTVs) were found in CEAS. Further investigation is imperative to elucidate the underlying pathophysiological mechanisms associated with CEAS, thereby facilitating the identification of effective therapeutic interventions.

Attenuated Expression of SLCO2A1 Caused by DNA Methylation in Pediatric Inflammatory Bowel Disease

BACKGROUND

SLCO2A1 encodes a prostaglandin (PG) transporter, and autosomal recessive pathogenic variants of this gene cause chronic enteropathy associated with SLCO2A1. It is unclear whether a heterozygous pathogenic variant of SLCO2A1 has a role in the pathogenesis of other types of inflammatory bowel disease (IBD). In this study, we investigated the possible involvement of a local epigenetic alteration in SLCO2A1 in patients with a heterozygous pathogenic variant.

METHODS

We conducted whole-exome sequencing of samples from 2 sisters with suspected monogenic IBD. In addition, we performed bisulfite sequencing using DNA extracted from their small and large intestine samples to explore epigenetic alterations.

RESULTS

A heterozygous splicing site variant, SLCO2A1:c.940 + 1G > A, was detected in both patients. To explore the possible involvement of epigenetic alterations, we analyzed protein and messenger RNA expression of SLCO2A1, and observed attenuated SLCO2A1 expression in the inflamed lesions of these patients compared with that in the control individuals. Furthermore, bisulfite sequencing indicated dense methylation in the promoter region of SLCO2A1 only in the inflamed lesions of both patients. The urinary PG metabolite levels in these patients were comparable to those in patients with chronic enteropathy associated with SLCO2A1 and higher than those in the control individuals. We found considerably higher levels of the metabolites in patient 1, who showed more severe symptoms than patient 2.

CONCLUSIONS

Local DNA methylation attenuated SLCO2A1 expression, which may evoke local inflammation of the mucosa by the unincorporated PG. These findings may improve our understanding of the epigenetic mechanisms underlying IBD development.

Primary hypertrophic osteoarthropathy: genetics, clinical features and management

Primary hypertrophic osteoarthropathy (PHO) is a genetic disorder mainly characterized by clubbing fingers, pachydermia and periostosis. Mutations in the HPGD or SLCO2A1 gene lead to impaired prostaglandin E2 (PGE2) degradation, thus elevating PGE2 levels. The identification of the causative genes has provided a better understanding of the underlying mechanisms. PHO can be divided into three subtypes according to its pathogenic gene and inheritance patterns. The onset age, sex ratio and clinical features differ among subtypes. The synthesis and signaling pathways of PGE2 are outlined in this review. Cyclooxygenase-2 (COX-2) is the key enzyme that acts as the rate-limiting step for prostaglandin production, thus COX-2 inhibitors have been used to treat this disease. Although this treatment showed effective results, it has side effects that restrain its use. Here, we reviewed the genetics, clinical features, differential diagnosis and current treatment options of PHO according to our many years of clinical research on the disease. We also discussed probable treatment that may be an option in the future.

Updates on the diagnosis and management of cryptogenic multifocal ulcerative stenosing enteropathy (CMUSE) and non-steroidal enteropathy

Crohn's disease and coeliac disease are well-known to induce ulcerations in the small-bowel. However, there is a group of very rare chronic ulcerative conditions of the small intestine that has emerged from the intestinal black box nearly 70 years ago, and that has gained interest with the advent of small-bowel capsule endoscopy and device-assisted enteroscopy. These distinct ulcerative enteropathies have come to our attention, and continue to reveal their aetiology and treatment options. Two distinct entities, called cryptogenic multifocal ulcerative stenosing enteritis/enteropathy (CMUSE) and chronic nonspecific multiple ulcers of the small intestine (CNSU) are gaining more clinical attention. CMUSE was first reported in Europe, whereas CNSU was exclusively diagnosed in Japanese patients. With the identification of susceptibility genes impacting prostaglandin metabolism, CMUSE and CNSU have become two distinct pathologies within the group of prostaglandin-associated enteropathies, to be differentiated from medication-induced enteropathies, especially non-steroidal anti-inflammatory drugs (NSAID)-induced enteropathy with similar intestinal ulcerations due to interference with prostaglandin metabolism. The current review provides an historical overview of CMUSE and CNSU publications, in addition to the currently available diagnostic and treatment options, and how to differentiate these rare enteropathies from NSAID-induced enteropathy.

Monogenic inflammatory bowel disease-genetic variants, functional mechanisms and personalised medicine in clinical practice

Over 100 genes are associated with monogenic forms of inflammatory bowel disease (IBD). These genes affect the epithelial barrier function, innate and adaptive immunity in the intestine, and immune tolerance. We provide an overview of newly discovered monogenic IBD genes and illustrate how a recently proposed taxonomy model can integrate phenotypes and shared pathways. We discuss how functional understanding of genetic disorders and clinical genomics supports personalised medicine for patients with monogenic IBD.

[Imaging Techniques and Differential Diagnosis for Inflammatory Bowel Disease]

The two main types of inflammatory bowel disease (IBD) are Crohn's disease and ulcerative colitis. Currently, when IBD is suspected, CT enterography is widely used as an initial imaging test because it can evaluate both the bowel wall and the outside of the bowel, helping to differentiate IBD from other diseases. When IBD is suspected, it is necessary to distinguish between Crohn's disease and ulcerative colitis. In most cases this is not difficult; however, in some cases, it is difficult and such cases are called IBD-unclassified. CT findings are often non-specific for ulcerative colitis, making it difficult to differentiate it from other diseases using imaging alone. In contrast, characteristic CT findings for Crohn's disease are often helpful in diagnosis, although diseases, such as tuberculous enteritis can mimic Crohn's disease. Recently, mutations in the gene encoding a prostaglandin transporter called SLCO2A1 have been discovered as the cause of the disease in some patients with multiple ulcers and strictures, similar to Crohn's disease. Therefore, genetic testing is being used to make a differential diagnosis.

N-glycosylation modifies prostaglandin E2 uptake by reducing cell surface expression of SLCO2A1

SLCO2A1 functions as a prostaglandin (PG) influx transporter to facilitate intracellular oxidation of PGs and its defect causes dysregulation of PG signaling and metabolism. This study aimed to clarify effects of N-glycosylation on functional SLCO2A1 expression. Putative N-glycosylation site(s) (N134, N478, and/or N491) of human SLCO2A1 were mutated to Q and wild-type (WT) and mutant forms were expressed in HEK293 and human epithelial cells. Molecular weight of WT decreased to nearly 55 kDa by PNGase F treatment and was identical to that of triple mutant (TM, i.e., N134Q/N478Q/N491Q). Transport affinity of TM for PGE₂ (K_m of 392.7 nM) was comparable to that of WT (K_m of 328.5 nM); however, immunoassays showed that TM cell surface expression remained at 24% of WT in HEK293 cells, resulting in a reduced cellular PGE₂ uptake. These results suggest N-glycosylation modifies cellular PGE₂ uptake by decreasing SLCO2A1 localization to the plasma membrane.

Eosinophilic enteritis requiring differentiation from chronic enteropathy associated with SLCO2A1 gene: A case report

BACKGROUND

Eosinophilic gastrointestinal disease (EGID) is a disorder characterized by infiltration of eosinophils causing mucosal damage and dysfunction of the gastrointestinal tract. The endoscopic findings of eosinophilic enteritis (EoN), an EGID variant, are nonspecific and occasionally difficult to diagnose. In contrast, chronic enteropathy associated with SLCO2A1 (CEAS) is a chronic persistent small intestinal disorder characterized by endoscopic findings such as multiple oblique and circular ulcers.

CASE SUMMARY

We report the case of a 10-year-old boy who had suffered abdominal pain and fatigue for the preceding 6 mo. He was referred to our institute for investigation of suspected gastrointestinal bleeding because of severe anemia with hypoproteinemia and positive fecal human hemoglobin. The upper and lower gastrointestinal endoscopic findings were normal; however, double-balloon small bowel endoscopy showed multiple oblique and circular ulcers with discrete margins and mild constriction of the intestinal lumen in the ileum. The findings were highly consistent with CEAS, but urine prostaglandin metabolites were within normal limits, and no previously reported mutations in the SLCO2A1 gene were identified. Histological evaluation demonstrated moderate to severe eosinophilic infiltration localized to the small intestine suggesting a diagnosis of EoN. Clinical remission was maintained with montelukast and a partial elemental diet, but emergent surgery for bowel obstruction due to small intestinal stenosis was performed two years after the initial treatment.

CONCLUSION

EoN should be considered in the differential diagnosis of CEAS-like small intestinal ulcerative lesions and normal urinary prostaglandin metabolite levels.

A Novel Chronic Enteropathy Associated with SLCO2A1 Gene Mutation: Enterography Findings in a Multicenter Korean Registry

OBJECTIVE

Chronic enteropathy associated with SLCO2A1 gene (CEAS) is a recently recognized disease. We aimed to evaluate the enterographic findings of CEAS.

MATERIALS AND METHODS

Altogether, 14 patients with CEAS were confirmed based on known SLCO2A1 mutations. They were registered in a multicenter Korean registry between July 2018 and July 2021. Nine of the patients (37.2 ± 13 years; all female) who underwent surgery-naïve-state computed tomography enterography (CTE) or magnetic resonance enterography (MRE) were identified. Two experienced radiologists reviewed 25 and 2 sets of CTE and MRE examinations, respectively, regarding the small bowel findings.

RESULTS

In initial evaluation, eight patients showed a total of 37 areas with mural abnormalities in the ileum on CTE, including 1-4 segments in six and > 10 segments in two patients. One patient showed unremarkable CTE. The involved segments were 10-85 mm (median, 20 mm) in length, 3-14 mm (median, 7 mm) in mural thickness, circumferential in 86.5% (32/37), and showed stratified enhancement in the enteric and portal phases in 91.9% (34/37) and 81.8% (9/11), respectively. Perienteric infiltration and prominent vasa recta were noted in 2.7% (1/37) and 13.5% (5/37), respectively. Bowel strictures were identified in six patients (66.7%), with a maximum upstream diameter of 31-48 mm. Two patients underwent surgery for strictures immediately after the initial enterography. Follow-up CTE and MRE in the remaining patients showed minimal-to-mild changes in the extent and thickness of the mural involvement for 17-138 months (median, 47.5 months) after initial enterography. Two patients required surgery for bowel stricture at 19 and 38 months of follow-up, respectively.

CONCLUSION

CEAS of the small bowel typically manifested on enterography in varying numbers and lengths of abnormal ileal segments that showed circumferential mural thickening with layered enhancement without perienteric abnormalities. The lesions caused bowel strictures that required surgery in some patients.

A patient with pachydermoperiostosis harboring SLCO2A1 variants with a history of differentiating from acromegaly

Pachydermoperiostosis (PDP) is a rare hereditary disease characterized by digital clubbing, pachydermia, and periostosis. We describe a Japanese male patient with PDP who was differentially diagnosed with acromegaly by identification of compound heterozygous variants in SLCO2A1. Recent studies have reported various clinical manifestations, as well as skeletal and dermal features, in patients with PDP. Genetic testing provided not only PDP diagnosis and differentiation from acromegaly, but also information about possible complications and comorbidities throughout life.

Novel pathogenic variants in SLCO2A1 causing autosomal dominant primary hypertrophic osteoarthropathy

Primary hypertrophic osteoarthropathy (PHO), or pachydermoperiostosis, is characterized by a clinical association including digital clubbing, periostosis and pachydermia. SLCO2A1 and HPGD genes are both responsible for PHO. The pathology is classically defined as an autosomal recessive disorder with clinical variability ranging from a mild to more severe phenotype. However, the hypothesis for an autosomal dominant form suggested for a long time was only demonstrated for the first time in 2021 for SLCO2A1. We aimed to detect a second pathogenic variant by a deep sequencing of the entire SLCO2A1 and HPGD genes, associated with functional transcription analysis in PHO patients harboring only one heterozygous variant. Among 10 PHO patients, 4 presented a single pathogenic or probably pathogenic novel variant in SLCO2A1 in heterozygous status (NM_005630.3: c.234+1G > A, c.1523_1524delCT, c.1625G > A and c.31delC), and the others carried homozygous pathogenic variants. For heterozygous forms, we found no additional pathogenic variant in HPGD or SLCO2A1. PHO can be a dominant form with age at disease onset later than that for the recessive form. This dominant form is not exceptional in young adults. In conclusion, both modes of inheritance of PHO explain the clinical variability and the difference in age at disease onset. Molecular analysis is especially required in the incomplete form to distinguish it from secondary hypertrophic osteoarthropathy.

Case report: Novel homozygous HPGD variant leads to primary hypertrophic osteoarthropathy with intussusception and acro-osteolysis in a Chinese family

Objective

To perform molecular genetic analysis of a patient diagnosed with primary hypertrophic osteoarthropathy (PHO) with malnourishment, intussusception, and acro-osteolysis.

Case presentation

At the age of 7 years, a boy born to a consanguineous couple was diagnosed with PHO attributed to delayed closure of the cranial suture, eczema, clubbing of fingers, and swelling of the knee and ankle. Clinical characteristics and follow-up data for 3 years were collected and analyzed. Trio whole-exome sequencing (WES) and copy number variant sequencing were used to screen for causative genetic variants. Candidate variants of the patient and his parents were confirmed by Sanger sequencing. When he was 7 years old, trio WES found that he had biallelic novel variants c.498 + 1G > A, inherited from his parents, in the HPGD gene. The patient was markedly malnourished. Ultrasonography and computed tomography showed intussusception with a gradual expansion of the duodenum, localized intestinal wall thickening, and acro-osteolysis. Cross-sectional blood tests showed that the patient had continuously decreased levels of serum 25-hydroxy vitamin D and serum ferritin at the age of 7and 10 years.

Conclusion

PHO due to HPGD defects is rare in pediatric patients, and finding homozygous novel c.498 + 1G > A has expanded the spectrum of causative variants of HPGD and provided a clue for genotype-phenotype correlation analysis. Similar to mouse model results, human HPGD deficiency may also cause abnormal digestive tract development, and related secondary vitamin D deficiency and acro-osteolysis should be considered in HPGD-related PHO.

Crohn-like disease affecting small bowel due to monogenic SLCO2A1 mutations: First cases of Chronic Enteropathy Associated with SLCO2A1 gene (CEAS) in France

INTRODUCTION

Multiple chronic ulcers of small intestine are mainly ascribed to Crohn's disease. Among possible differential diagnoses are chronic ulcers of small bowel caused by abnormal activation of the prostaglandin pathway either in the archetypal but uncommon non-steroidal anti-inflammatory drug (NSAID)-induced enteropathy, or in rare monogenic disorders due to PLA2G4A and SLCO2A1 mutations. SLCO2A1 variants are responsible for CEAS (Chronic enteropathy associated with SLCO2A1), a syndrome which was exclusively reported in patients of Asian origin. Herein, we report the case of two French female siblings with CEAS.

CASE REPORT

P1 underwent iterative bowel resections (removing 1 meter of small bowel in total) for recurrent strictures and perforations. Her sister P2 had a tight duodenal stricture which required partial duodenectomy. Next-generation sequencing was performed on P1's DNA and identified 2 compound heterozygous variants in exon 12 in SLCO2A1, which were also present in P2.

CONCLUSION

CEAS can be detected within the European population and raise the question of its incidence and recognition outside Asia. Presence of intractable recurrent ulcerations of the small intestine mimicking Crohn's disease with concentric stricture should motivate a genetic search for SLCO2A1 mutations, particularly in the context of family history or consanguinity.

Chronic enteropathy associated with SLCO2A1 gene and hereditary fructose intolerance: A coincidence of two rare diseases

Chronic enteropathy associated with SLCO2A1 gene (CEAS) is a rare disorder characterized by multiple small intestine ulcers. Patients with CEAS typically present with chronic anemia and gastrointestinal bleeding. Besides CEAS, SLCO2A1 mutations cause primary hypertrophic osteoarthropathy (PHO) which is considered as an extraintestinal manifestation in CEAS patients. Since CEAS and Crohn's disease are clinically indistinguishable, patients are often misdiagnosed with Crohn's disease. Herein, we describe a 4-year-old Turkish girl with CEAS due to homozygous pathogenic variant (c.656C > T) in SLCO2A1 with concomitant hereditary fructose intolerance (HFI) caused by homozygous pathogenic variant (c.1005C > G) in ALDOB. Prompt restriction of fructose, sucrose and sorbitol resulted in hepatomegaly regression and mild amelioration of patient's symptoms. Despite budesonide and azathioprine treatments, patient's protein losing enteropathy and chronic anemia did not improve. Although previous CEAS cases were reported from East Asian countries, it is likely to occur in people from other geographic areas. CEAS seems to be underdiagnosed and high index of suspicion is required for the diagnosis of this rare entity. Patients with prior diagnosis of Crohn's disease with no response to immunosuppressive treatment or anti-TNF therapy should be re-evaluated for possible CEAS diagnosis.

Functional analysis of mutant SLCO2A1 transporters found in patients with chronic enteropathy associated with SLCO2A1

BACKGROUND AND AIM

Chronic enteropathy associated with the solute carrier organic anion transporter family member 2A1 (SLCO2A1), or CEAS, causes anemia and hypoalbuminemia in young people. Dysfunction of the SLCO2A1 transporter protein is thought to involve genetic mutation, but mutant proteins have not been functionally characterized. We examined the prostaglandin E₂ (PGE₂ ) transport ability of recombinant SLCO2A1 proteins containing 11 SLCO2A1 mutations found in CEAS patients.

METHODS

Wild-type and mutant SLCO2A1 proteins were forcibly expressed in Xenopus laevis oocytes, and measurements of PGE₂ uptake and transport capacity were compared. The membrane protein topology and functionality of the eight SLCO2A1 mutations involving single-nucleotide substitutions were predicted using computer analysis.

RESULTS

The extent of functional disruption of the 11 SLCO2A1 mutations identified in CEAS patients was variable, with 10 mutations (421GT, 547GA, 664GA, 770GA, 830dupT, 830delT, 940 + 1GA, 1372GT, 1647GT, and 1807CT) resulting in loss or reduction of PGE₂ transport, excluding 97GC.

CONCLUSION

PGE₂ transport ability of recombinant SLCO2A1 in X. laevis oocytes was hindered in 10/11 SLCO2A1 mutations identified in patients with CEAS. Further studies on the relationships between the different mutations and PGE₂ transport and clinical features, such as severity, are needed.

Chronic Enteropathy Associated with Solute Carrier Organic Anion Transporter Family, Member 2A1 (SLCO2A1) with Positive Immunohistochemistry for SLCO2A1 Protein

Chronic enteropathy associated with solute carrier organic anion transporter family, member 2A1 (SLCO2A1) (CEAS) is a rare autosomal recessive hereditary disease characterized by chronic persistent anemia and hypoproteinemia. Its diagnosis typically requires a genetic analysis. The efficacy of immunohistochemical staining with SLCO2A1 polyclonal antibody as a pre-diagnostic tool for CEAS has been previously reported. We herein report a patient with CEAS in whom immunohistochemical staining confirmed SLCO2A1 protein expression. The immunopositive results may have been due to nonsense-mediated RNA decay. As immunohistochemical staining of SLCO2A1 protein may show immunopositive results, a genetic analysis should also be performed when CEAS is strongly clinically suspected.

Localization of Xenobiotic Transporters Expressed at the Human Blood-Testis Barrier

The blood-testis barrier (BTB) is formed by basal tight junctions between adjacent Sertoli cells (SCs) of the seminiferous tubules and acts as a physical barrier to protect developing germ cells in the adluminal compartment from reproductive toxicants. Xenobiotics, including antivirals, male contraceptives, and cancer chemotherapeutics, are known to cross the BTB, although the mechanisms that permit barrier circumvention are generally unknown. This study used immunohistological staining of human testicular tissue to determine the site of expression for xenobiotic transporters that facilitate transport across the BTB. Organic anion transporter (OAT) 1, OAT2, and organic cation transporter, novel (OCTN) 1 primarily localized to the basal membrane of SCs, whereas OCTN2, multidrug resistance protein (MRP) 3, MRP6, and MRP7 localized to SC basal membranes and peritubular myoid cells (PMCs) surrounding the seminiferous tubules. Concentrative nucleoside transporter (CNT) 2 localized to Leydig cells (LCs), PMCs, and SC apicolateral membranes. Organic cation transporter (OCT) 1, OCT2, and OCT3 mostly localized to PMCs and LCs, although there was minor staining in developing germ cells for OCT3. Organic anion transporting polypeptide (OATP) 1A2, OATP1B1, OATP1B3, OATP2A1, OATP2B1, and OATP3A1-v2 localized to SC basal membranes with diffuse staining for some transporters. Notably, OATP1C1 and OATP4A1 primarily localized to LCs. Positive staining for multidrug and toxin extrusion protein (MATE) 1 was only observed throughout the adluminal compartment. Definitive staining for CNT1, OAT3, MATE2, and OATP6A1 was not observed. The location of these transporters is consistent with their involvement in the movement of xenobiotics across the BTB. Altogether, the localization of these transporters provides insight into the mechanisms of drug disposition across the BTB and will be useful in developing tools to overcome the pharmacokinetic and pharmacodynamic difficulties presented by the BTB. SIGNIFICANCE STATEMENT: Although the total mRNA and protein expression of drug transporters in the testes has been explored, the localization of many transporters at the blood-testis barrier (BTB) has not been determined. This study applied immunohistological staining in human testicular tissues to identify the cellular localization of drug transporters in the testes. The observations made in this study have implications for the development of drugs that can effectively use transporters expressed at the basal membranes of Sertoli cells to bypass the BTB.

Cryptogenic multifocal ulcerating stenosing enteritis and other under-recognised small bowel inflammatory enteropathies

PURPOSE OF REVIEW

Capsule endoscopy and more sensitive radiological techniques have resulted in more enteropathies being detected. A rare disease of unknown aetiology, 'cryptogenic multifocal ulcerating stenosing enteritis' or 'chronic nonspecific multiple ulcers of the small intestine' (CNSU), has long been recognised. This review aims to describe how disease can be better diagnosed and differentiated from other small bowel inflammatory disorders.

RECENT FINDINGS

Genetic studies have shown that some patients with CNSU (the term used in Japanese studies) express SLCO2A1 gene mutations, a gene which encodes a prostaglandin transporter expressed on vascular endothelium, allowing a more specific diagnosis of 'chronic enteropathy associated with SLCO2A1'. Mutations in the PLA2G4A gene result in cytosolic phospholipase A2α deficiency and reduced arachidonic acid for prostaglandin synthesis leading to a severe ulcerating, stenosing and fistulating small bowel disease.

SUMMARY

A 'prostaglandin-related enteropathy' should be considered in patients with atypical small bowel ulceration and stenosis. Genetic analysis will allow the detection of SLCO2A1 and PLA2G4A gene mutations. However, a careful history of medication use and a urinary metabolite screen may reveal the use of nonsteroidal anti-inflammatory drugs, a common cause of small bowel injury which is well recognised as being mediated by prostaglandin inhibition.

Practical guidance for the diagnosis and management of secondary hypogammaglobulinemia: A Work Group Report of the AAAAI Primary Immunodeficiency and Altered Immune Response Committees

Secondary hypogammaglobulinemia (SHG) is characterized by reduced immunoglobulin levels due to acquired causes of decreased antibody production or increased antibody loss. Clarification regarding whether the hypogammaglobulinemia is secondary or primary is important because this has implications for evaluation and management. Prior receipt of immunosuppressive medications and/or presence of conditions associated with SHG development, including protein loss syndromes, are histories that raise suspicion for SHG. In patients with these histories, a thorough investigation of potential etiologies of SHG reviewed in this report is needed to devise an effective treatment plan focused on removal of iatrogenic causes (eg, discontinuation of an offending drug) or treatment of the underlying condition (eg, management of nephrotic syndrome). When iatrogenic causes cannot be removed or underlying conditions cannot be reversed, therapeutic options are not clearly delineated but include heightened monitoring for clinical infections, supportive antimicrobials, and in some cases, immunoglobulin replacement therapy. This report serves to summarize the existing literature regarding immunosuppressive medications and populations (autoimmune, neurologic, hematologic/oncologic, pulmonary, posttransplant, protein-losing) associated with SHG and highlights key areas for future investigation.

Advanced endoscopy for the management of inflammatory digestive diseases: Review of the Japan Gastroenterological Endoscopy Society core session

A series of workshops entitled "Advanced endoscopy in the management of inflammatory digestive disease" was held at the 97^th to 100^th biannual meeting of the Japan Gastroenterological Endoscopy Society. During these core sessions, research findings concerning various endoscopic practices in the field of inflammatory bowel disease (IBD) were presented, and meaningful discussions were shared on the evolving role and future challenges of endoscopy in IBD. This article reviews these core sessions and discusses current topics on the role of endoscopy, focusing on the diagnosis, disease monitoring, mucosal healing assessments, cancer surveillance, and therapeutic interventions in IBD.

Four Variants of SLCO2A1 Identified in Three Chinese Patients with Chronic Enteropathy Associated with the SLCO2A1 Gene

BACKGROUND

Chronic enteropathy associated with the SLCO2A1 gene (CEAS) is an enteropathy characterized by multiple small intestinal ulcers of nonspecific histology, also known as chronic nonspecific multiple ulcers of the small intestine. The SLCO2A1 gene encodes a prostaglandin transporter (PGT).

AIMS

The aim of this study was to investigate the clinical characteristics of ten Chinese patients with intestinal ulcers of unknown origin, screen them for variants of SLCO2A1, and to investigate the expression of PGT in the small intestinal mucosa of patients with CEAS.

METHODS

Ten Chinese patients with intestinal ulcers of unknown origin were included in this study. Blood samples were collected for whole-exome sequencing and Sanger sequencing of candidate gene variants. Immunohistochemical staining was used to investigate the expression of PGT.

RESULTS

These ten patients were clinically diagnosed with intestinal ulcers of unknown origin based on criteria established according to earlier publications. Three of them were genetically diagnosed as having CEAS and four candidate variants of the SLCO2A1 gene were identified, among which c.941-1G>A, c.178G>A and c.1681C>T were detected in patients with CEAS for the first time. The terminal ileum was involved in all three patients with CEAS in our study, which was different from the results of Japanese patients. The expression of PGT in the vascular endothelial cells of the intestinal mucosa tissues of patients with CEAS was negative or intermediate.

CONCLUSION

We summarized the clinical data of ten Chinese patients with intestinal ulcers of unknown origin and identified three novel SLCO2A1 variants from three patients with CEAS. This study improves our understanding of CEAS and broadens the spectrum of SLCO2A1 variants known to cause CEAS.

Asymptomatic small intestinal ulcerative lesions: Obesity and Helicobacter pylori are likely to be risk factors

It is often difficult to explain why ulcerative lesions are found in the small intestine because there are no obvious aggressors such as gastric acid. In particular, the treatment of small intestinal ulcerative lesions in asymptomatic patients with no symptoms, normal physical examinations, and normal blood test findings is not well documented. According to a summary of capsule endoscopy studies in healthy subjects, approximately 10% of subjects have small intestinal mucosal breaks. The number of mucosal breaks in these instances is approximately 1-3. We examined small intestinal mucosal breaks in healthy subjects recruited from our past two studies. Mucosal breaks were observed in approximately 10% of subjects, and the average number was 0.24 ± 1.21. The number of mucosal breaks in the small intestine was correlated with body mass index and was significantly higher in Helicobacter pylori-infected subjects and higher in males. These results indicate that 1-2 small ulcerative lesions, such as erosions in the small intestine, can be considered to be in the normal range, and close examination is not required. It is assumed that a follow-up medical examination is required for such asymptomatic persons. The presence of many small ulcerative lesions or an unequivocal ulcer indicates an abnormality for which close examination is desired. However, in many cases, it is sufficient to scrutinize after detecting anemia, but it is difficult to make a judgment due to insufficient reports, and future studies are required.

The ATP-Releasing Maxi-Cl Channel: Its Identity, Molecular Partners and Physiological/Pathophysiological Implications

The Maxi-Cl phenotype accounts for the majority (app. 60%) of reports on the large-conductance maxi-anion channels (MACs) and has been detected in almost every type of cell, including placenta, endothelium, lymphocyte, cardiac myocyte, neuron, and glial cells, and in cells originating from humans to frogs. A unitary conductance of 300-400 pS, linear current-to-voltage relationship, relatively high anion-to-cation selectivity, bell-shaped voltage dependency, and sensitivity to extracellular gadolinium are biophysical and pharmacological hallmarks of the Maxi-Cl channel. Its identification as a complex with SLCO2A1 as a core pore-forming component and two auxiliary regulatory proteins, annexin A2 and S100A10 (p11), explains the activation mechanism as Tyr23 dephosphorylation at ANXA2 in parallel with calcium binding at S100A10. In the resting state, SLCO2A1 functions as a prostaglandin transporter whereas upon activation it turns to an anion channel. As an efficient pathway for chloride, Maxi-Cl is implicated in a number of physiologically and pathophysiologically important processes, such as cell volume regulation, fluid secretion, apoptosis, and charge transfer. Maxi-Cl is permeable for ATP and other small signaling molecules serving as an electrogenic pathway in cell-to-cell signal transduction. Mutations at the SLCO2A1 gene cause inherited bone and gut pathologies and malignancies, signifying the Maxi-Cl channel as a perspective pharmacological target.

Can cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) be diagnosed in a patient with non-steroidal anti-inflammatory drug exposure?

The differential diagnosis for ulcerating small bowel strictures is extensive and includes exposure to non-steroidal anti-inflammatory drugs (NSAIDs), Crohn's disease, infections, gastrointestinal lymphoma and vasculopathy. It also encompasses the exceptionally rare and poorly understood diagnosis of cryptogenic multifocal ulcerative stenosing enterocolitis (CMUSE), often a diagnosis of exclusion and considerable difficulty. We present a case of persistent proximal jejunal ulcerating stenoses in a 75-year-old Caucasian man, which continued despite cessation of NSAIDs. After extensive clinical, radiographic, laboratory and ultimately surgical pathological appraisal-as well as failure to improve with both misoprostol and budesonide-he was diagnosed with CMUSE and managed with limited small bowel resection. In the presentation of this case, we aim to underscore the diagnostic challenges that clinicians face in differentiating CMUSE from other more common diagnoses, particularly NSAIDs-induced enteropathy.

Primary hypertrophic osteoarthropathy with severe arthralgia identified by gene mutation of SLCO2A1

Male, 41 years old (yo) had been complaining of severe arthralgia. Past History indicated obstruction of intestinal tract at 12 yo and gastric ulcer at 13 yo. He had been suffered from polyarthralgia especially at PIP and MP joints of both hands from 38 yo. Finally, he complained severe arthralgia at PIP and MP joints with clubbed fingers without swelling. Biochemical finding indicated negative rheumatoid factor and anti-CCP antibody and normal MMP-3 level, but slightly increased CRP and ESR levels. Radiological finding indicated periostosis of　long bone without bone erosion and osteoporosis. His facial appearance was acromegalic with cutaneous manifestation of pachydermia and cutis vertices gyrate without abnormal growth hormone response. Histological findings of skin indicated oedema and hyperplasia of sebaceous glands with infiltration of lymphocytes around small blood vessels compatible with pachydermoperiostosis. In this case mutation of SLCO2A1 gene, which coded prostaglandin transport protein, was identified. The mutation c.940 + 1G > A of SLCO2A1 gene results in deletion of exon 7 and truncation of PG transporter (p.Arg288Glyfs*7). We suggest that severe arthralgia was originated from over production of prostaglandin E2. Further studies will be required.

Recent advances in studies of SLCO2A1 as a key regulator of the delivery of prostaglandins to their sites of action

Solute carrier organic anion transporter family member 2A1 (SLCO2A1, also known as PGT, OATP2A1, PHOAR2, or SLC21A2) is a plasma membrane transporter consisting of 12 transmembrane domains. It is ubiquitously expressed in tissues, and mediates the membrane transport of prostaglandins (PGs, mainly PGE₂, PGF_2α, PGD₂) and thromboxanes (e.g., TxB₂). SLCO2A1-mediated transport is electrogenic and is facilitated by an outwardly directed gradient of lactate. PGs imported by SLCO2A1 are rapidly oxidized by cytoplasmic 15-hydroxyprostaglandin dehydrogenase (15-PGDH, encoded by HPGD). Accumulated evidence suggests that SLCO2A1 plays critical roles in many physiological processes in mammals, and it is considered a potential pharmacological target for diabetic foot ulcer treatment, antipyresis, and non-hormonal contraception. Furthermore, whole-exome analyses suggest that recessive inheritance of SLCO2A1 mutations is associated with two refractory diseases, primary hypertrophic osteoarthropathy (PHO) and chronic enteropathy associated with SLCO2A1 (CEAS). Intriguingly, SLCO2A1 is also a key component of the Maxi-Cl channel, which regulates fluxes of inorganic and organic anions, including ATP. Further study of the bimodal function of SLCO2A1 as a transporter and ion channel is expected to throw new light on the complex pathology of human diseases. Here, we review and summarize recent information on the molecular functions of SLCO2A1, and we discuss its pathophysiological significance.

Tag-less patency capsule for suspected small bowel stenosis: Nationwide multicenter prospective study in Japan

STUDY AIMS

The PillCam patency capsule (PPC) is an Agile tag-less patency capsule used to evaluate gastrointestinal (GI) patency. We determined the appropriate use of PPC to preclude subsequent small bowel capsule endoscopy (SBCE) retention.

METHODS

This prospective multicenter study consecutively enrolled patients indicated for SBCE with suspected or established small bowel stenosis. Excretion of an intact PPC or its radiologic visualization in the large bowel was considered GI patency. Primary and secondary study endpoints were SBCE retention rates in patients with confirmed patency and identification of factors associated with patency and SBCE retention, respectively.

RESULTS

Of 1096 patients enrolled in the study, patency was confirmed in 976 (89.1%). PPC excretion occurred in 579 patients. Of the remaining 517 patients, patency was confirmed using imaging modalities in 401 (77.5%). SBCE retention occurred in five (0.51%) of 963 patients who underwent SBCE: 1.0% in established Crohn's disease (CD) patients, 0% in suspected CD, 0% in tumors, and 1.6% in patients with obscure GI bleeding, for which PPC localization had been radiographically misinterpreted. The non-confirmation of patency was associated with established CD, stenosis identified using imaging modalities, abdominal fullness, serum albumin levels <4.0 g/dL, and previous small bowel obstruction (adjusted odds ratios: 4.21, 2.60, 2.47, 2.12, and 2.00; 95% confidence intervals: 2.62-6.78, 1.62-4.17, 1.43-4.27, 1.32-3.40, and 1.15-3.47, respectively).

CONCLUSIONS

The PillCam™ patency capsule helped preclude SBCE retention in most patients, but its accurate localization was essential for cases without excretion (Study registered the University Hospital Medical Information Network, #UMIN000010513).

KRAB zinc finger protein diversification drives mammalian interindividual methylation variability

Most transposable elements (TEs) in the mouse genome are heavily modified by DNA methylation and repressive histone modifications. However, a subset of TEs exhibit variable methylation levels in genetically identical individuals, and this is associated with epigenetically conferred phenotypic differences, environmental adaptability, and transgenerational epigenetic inheritance. The evolutionary origins and molecular mechanisms underlying interindividual epigenetic variability remain unknown. Using a repertoire of murine variably methylated intracisternal A-particle (VM-IAP) epialleles as a model, we demonstrate that variable DNA methylation states at TEs are highly susceptible to genetic background effects. Taking a classical genetics approach coupled with genome-wide analysis, we harness these effects and identify a cluster of KRAB zinc finger protein (KZFP) genes that modifies VM-IAPs in trans in a sequence-specific manner. Deletion of the cluster results in decreased DNA methylation levels and altered histone modifications at the targeted VM-IAPs. In some cases, these effects are accompanied by dysregulation of neighboring genes. We find that VM-IAPs cluster together phylogenetically and that this is linked to differential KZFP binding, suggestive of an ongoing evolutionary arms race between TEs and this large family of epigenetic regulators. These findings indicate that KZFP divergence and concomitant evolution of DNA binding capabilities are mechanistically linked to methylation variability in mammals, with implications for phenotypic variation and putative paradigms of mammalian epigenetic inheritance.

A novel mutation in the SLCO2A1 gene, encoding a prostaglandin transporter, induces chronic enteropathy

Chronic enteropathy associated with SLCO2A1 gene (CEAS) is caused by loss-of-function mutations in SLCO2A1, which encodes a prostaglandin (PG) transporter. In this study, we report a sibling case of CEAS with a novel pathogenic variant of the SLCO2A1 gene. Compound heterozygous variants in SLCO2A1 were identified in an 8-year-old boy and 12-year-old girl, and multiple chronic nonspecific ulcers were observed in the patients using capsule endoscopy. The splice site mutation (c.940 + 1G>A) of the paternal allele was previously reported to be pathogenic, whereas the missense variant (c.1688T>C) of the maternal allele was novel and had not yet been reported. The affected residue (p.Leu563Pro) is located in the 11th transmembrane domain (helix 11) of SLCO2A1. Because SLCO2A1 mediates the uptake and clearance of PGs, the urinary PG metabolites were measured by liquid chromatography coupled to tandem mass spectrometry. The urinary tetranor-prostaglandin E metabolite levels in the patients were significantly higher than those in unaffected individuals. We established cell lines with doxycycline-inducible expression of wild type SLCO2A1 (WT-SLCO2A1) and the L563P mutant. Immunofluorescence staining showed that WT-SLCO2A1 and the L563P mutant were dominantly expressed on the plasma membranes of these cells. Cells expressing WT-SLCO2A1 exhibited time- and dose-dependent uptake of PGE₂, while the mutant did not show any uptake activity. Residue L563 is very close to the putative substrate-binding site in SLCO2A1, R561 in helix 11. However, in a molecular model of SLCO2A1, the side chain of L563 projected outside of helix 11, indicating that L563 is likely not directly involved in substrate binding. Instead, the substitution of Pro may twist the helix and impair the transporter function. In summary, we identified a novel pathogenic variant of SLCO2A1 that caused loss-of-function and induced CEAS.

Obscure gastrointestinal bleeding caused by congenital enteropathy in a Chinese young child-a case report

Background

SLCO2A1 was recently reported to cause nonspecific ulcers at small bowel, it was named as chronic enteropathy associated with SLCO2A1 (CEAS). It was rarely reported beyond the Japanese population.

Case presentation

A 4-year-5-month old girl presented with intractable anemia since 1-year-3-month. Her stool occult blood test was positive and the result of esophagogastroduodenoscopy and colonoscopy were normal. She was considered as obscure gastrointestinal bleeding. The magnetic resonance enterography and ultrasound of small intestinal revealed segmental thickening of small bowel. The capsule endoscopy detected ulcers, erosion and slightly stenosis near the site of junction of jejunum and ileum. She was considered chronic non-specific multiple ulcers of the small intestine and was advised to have whole exon sequencing. She was treated with exclusive enteral nutrition and iron supplement for two months. However, she was not responsive to this treatment, then she had three doses of infliximab. At the same time, the next-generation sequencing of this patient revealed two novel compound heterozygous mutations in SLCO2A1. She was diagnosed with CEAS and was treated with oral mercaptopurine. Her hemoglobin level was stable and the serum albumin level was slightly decreased during the follow up.

Conclusion

CEAS may present as nonspecific small bowel ulcers, and misinterpret as small bowel Crohn’s disease. Genetic tests may help with the precise diagnosis of small bowel ulcers.

Comprehensive Targeted Sequencing Identifies Monogenic Disorders in Patients With Early-onset Refractory Diarrhea

OBJECTIVES

Causes of early-onset refractory diarrhea include exudative diarrhea associated with very early-onset inflammatory bowel diseases, osmotic or secretory diarrhea, and protein-losing enteropathy. Monogenic disorders are included in these diseases, yet a comprehensive genetic analysis has not been fully established.

METHODS

We established targeted gene panels covering all responsible genes for early-onset diarrhea. In total, 108 patients from 15 institutions were enrolled in this study. We collected clinical data from all patients. Seventy-three patients with exudative diarrhea, 4 with osmotic or secretory diarrhea and 8 with protein-losing enteropathy were subjected to genetic analysis.

RESULTS

A total of 15 out of the 108 enrolled patients (13.9%) were identified as monogenic. We identified 1 patient with RELA, 2 with TNFAIP3, 1 with CTLA4, 1 with SLCO2A1, 4 with XIAP, 3 with IL10RA, 1 with HPS1, 1 with FOXP3, and 1 with CYBB gene mutations. We also identified 1 patient with NFKB2 and 1 with TERT mutations from the gene panel for primary immunodeficiency syndromes. The patient with refractory diarrhea caused by heterozygous truncated RelA protein expression is the first case identified worldwide, and functional analysis revealed that the mutation affected nuclear factor kappa B signaling. Genotypes were significantly associated with the clinical and pathological findings in each patient.

CONCLUSIONS

We identified variable monogenic diseases in the patients and found that genes responsible for primary immunodeficiency diseases were frequently involved in molecular pathogenesis. Comprehensive genetic analysis was useful for accurate molecular diagnosis, understanding of underlying pathogenesis, and selecting the optimal treatment for patients with early-onset refractory diarrhea.An infographic for this article is available at: http://links.lww.com/MPG/B853.

Very Early-Onset Inflammatory Bowel Disease: A Challenging Field for Pediatric Gastroenterologists

With the increasing number of children with inflammatory bowel disease (IBD), very early-onset IBD (VEO-IBD), defined as IBD that is diagnosed or that develops before 6 years of age, has become a field of innovation among pediatric gastroenterologists. Advances in genetic testing have enabled the diagnosis of IBD caused by gene mutations, also known as monogenic or Mendelian disorder-associated IBD (MD-IBD), with approximately 60 causative genes reported to date. The diagnosis of VEO-IBD requires endoscopic and histological evaluations. However, satisfactory small bowel imaging studies may not be feasible in this small population. Both genetic and immunological approaches are necessary for the diagnosis of MD-IBD, which can differ among countries according to the available resources. As a result of the use of targeted gene panels covered by the national health insurance and the nationwide research project investigating inborn errors of immunity, an efficient approach for the diagnosis of MD-IBD has been developed in Japan. Proper management of VEO-IBD by pediatric gastroenterologists constitutes a challenge. Some MD-IBDs can be curable by allogenic hematopoietic stem cell transplantation. With an understanding of the affected gene functions, targeted therapies are being developed. Social and psychological support systems for both children and their families should also be provided to improve their quality of life. Multidisciplinary team care would contribute to early diagnosis, proper therapeutic interventions, and improved quality of life in patients and their families.

Retrospective study of the differential diagnosis between cryptogenic multifocal ulcerous stenosing enteritis and small bowel Crohn's disease

BACKGROUND

Being a rare disease, cryptogenic multifocal ulcerous stenosing enteritis (CMUSE) is easily misdiagnosed as small bowel Crohn's disease (SBCD).

AIMS

This study was aimed to compare clinical features of CMUSE to SBCD.

METHODS

Fourteen patients with CMUSE and 61 patients with SBCD were retrospectively analyzed.

RESULTS

Hematochezia was more frequent in CMUSE patients (10, 71.4% vs 23, 37.7%, P = 0.022), while diarrhea was more common in SBCD patients (23, 37.7% vs 0, 0.0%, P = 0.015). More patients with CMUSE developed intestinal stenosis than with SBCD (14, 100% vs 37, 60.7%, P = 0.011). 30 (50.0%) SBCD patients and none CMUSE patients had an elevated erythrocyte sedimentation rate level (P = 0.001). Extra-enteric findings found by computed tomography enterography were significantly more prevalent in SBCD patients than in CMUSE patients (25,71.4% vs 3,25%, P = 0.013). Longitudinal ulcers found by endoscopy were more common in SBCD patients (16, 37.2% vs 0, 0.0%, P = 0.041), while circumferential ulcers were more common in CMUSE patients (6, 54.6% vs 8, 18.6%, P = 0.041). All ulcers observed in CMUSE patients were within mucosal and submucosal layers, but 8 (44.4%) SBCD patients had deep ulcers that reached beyond submucosal layers (P = 0.003). Ulcers were located at strictures in 9 (90.0%) CMUSE patients but only in 1 (5.6%) SBCD patient (P = 0.000).

CONCLUSIONS

Gastrointestinal symptoms, erythrocyte sedimentation rate levels, radiologic, endoscopic and pathologic features help to distinguish CMUSE from SBCD.

Slco2a1 deficiency exacerbates experimental colitis via inflammasome activation in macrophages: a possible mechanism of chronic enteropathy associated with SLCO2A1 gene

Loss-of-function mutations in the solute carrier organic anion transporter family, member 2a1 gene (SLCO2A1), which encodes a prostaglandin (PG) transporter, have been identified as causes of chronic nonspecific multiple ulcers in the small intestine; however, the underlying mechanisms have not been revealed. We, therefore, evaluated the effects of systemic knockout of Slco2a1 (Slco2a1^−/−) and conditional knockout in intestinal epithelial cells (Slco2a1^ΔIEC) and macrophages (Slco2a1^ΔMP) in mice with dextran sodium sulphate (DSS)-induced acute colitis. Slco2a^−/− mice were more susceptible to DSS-induced colitis than wild-type (WT) mice, but did not spontaneously develop enteritis or colitis. The nucleotide-binding domain, leucine-rich repeats containing family, pyrin domain-containing-3 (NLRP3) inflammasome was more strongly upregulated in colon tissues of Slco2a^−/− mice administered DSS and in macrophages isolated from Slco2a1^−/− mice than in the WT counterparts. Slco2a1^ΔMP, but not Slco2a1^ΔIEC mice, were more susceptible to DSS-induced colitis than WT mice, partly phenocopying Slco2a^−/− mice. Concentrations of PGE₂ in colon tissues and macrophages from Slco2a1^−/− mice were significantly higher than those of WT mice. Blockade of inflammasome activation suppressed the exacerbation of colitis. These results indicated that Slco2a1-deficiency increases the PGE₂ concentration, resulting in NLRP3 inflammasome activation in macrophages, thus exacerbating intestinal inflammation.

Estimated Prevalence of Cronkhite-Canada Syndrome, Chronic Enteropathy Associated With SLCO2A1 Gene, and Intestinal Behçet's Disease in Japan in 2017: A Nationwide Survey

Background

Cronkhite-Canada syndrome (CCS), chronic enteropathy associated with SLCO2A1 gene (CEAS), and intestinal Behçet’s disease (BD) are classified as intractable intestinal disorders in Japan. However, the national prevalence of these diseases remains unknown. We performed a nationwide survey to estimate the patient numbers and prevalence rates of these diseases throughout Japan in 2017.

Methods

We conducted a mail-based survey targeting hospitals across Japan to estimate the annual numbers of patients with CCS, CEAS, and intestinal BD in 2017. Using a stratified random sampling method, we selected 2,979 hospital departments and asked them to report the number of patients who met specific diagnostic criteria. The total number of patients for each disease was estimated by multiplying the reported numbers by the reciprocal of the sampling rate and response rate. The corresponding prevalence rates per 1,000,000 population were calculated based on the mid-year population of Japan in 2017.

Results

The overall survey response rate was 68.1% (2,029 departments). The estimated numbers of patients with CCS, CEAS, and intestinal BD were 473 (95% confidence interval [CI], 357–589), 388 (95% CI, 289–486), and 3,139 (95% CI, 2,749–3,529), respectively; the prevalence rates per 1,000,000 population were 3.7 (male: 4.0; female: 3.5), 3.1 (male: 3.0; female: 3.1), and 24.8 (male: 24.5; female: 25.0), respectively. The male-to-female ratios were 1.10, 0.94, and 0.93 for patients with CCS, CEAS, and intestinal BD, respectively.

Conclusions

Estimates of the national prevalence of CCS, CEAS, and intestinal BD in Japan were generated and found to be higher than those previously reported.

Characteristic Facial Appearance Was the Key to Diagnosing Chronic Enteropathy Associated with SLCO2A1-associated Primary Hypertrophic Osteoarthropathy

Patients with chronic enteropathy associated with SLCO2A1 (CEAS) develop multiple circular, longitudinal, or eccentric ulcers in the ileum. It is sometimes difficult to distinguish CEAS from Crohn's disease. CEAS and primary hypertrophic osteoarthropathy (PHO) are together known to be caused by a mutation of SLCO2A1 gene. The case of a 65-year-old man whose characteristic appearance due to pachydermia of the forehead folds led to the diagnosis of CEAS with PHO is presented.

Evidence-based diagnosis and clinical practice guidelines for intestinal Behçet's disease 2020 edited by Intractable Diseases, the Health and Labour Sciences Research Grants

Behçet's disease (BD) is an intractable systemic inflammatory disease characterized by four main symptoms: oral and genital ulcers and ocular and cutaneous involvement. The Japanese diagnostic criteria of BD classify intestinal BD as a specific disease type. Volcano-shaped ulcers in the ileocecum are a typical finding of intestinal BD, and punched-out ulcers can be observed in the intestine or esophagus. Tumor necrosis factor inhibitors were first approved for the treatment of intestinal BD in Japan and have been used as standard therapy. In 2007 and 2014, the Japan consensus statement for the diagnosis and management of intestinal BD was established. Recently, evidence-based JSBD (Japanese Society for BD) Clinical Practice Guidelines for BD (Japanese edition) were published, and the section on intestinal BD was planned to be published in English. Twenty-eight important clinical questions (CQs) for diagnosis (CQs 1-6), prognosis (CQ 7), monitoring and treatment goals (CQs 8-11), medical management and general statement (CQs 12-13), medical treatment (CQs 14-22), and surgical treatment (CQs 23-25) of BD and some specific situations (CQs 26-28) were selected as unified consensus by the members of committee. The statements and comments were made following a search of published scientific evidence. Subsequently, the levels of recommendation were evaluated based on clinical practice guidelines in the Medical Information Network Distribution Service. The degree of agreement was calculated using anonymous voting. We also determined algorithms for diagnostic and therapeutic approaches for intestinal BD. The present guidelines will facilitate decision making in clinical practice.

Chronic Enteropathy Associated with SLCO2A1 with Pachydermoperiostosis

A 49-year-old man complained of chronic palpitation and shortness of breath, which had recently become exacerbated. A blood examination indicated severe refractory anemia and hypoproteinemia. Physical examinations revealed anemia, a systolic murmur, and spoon nails. Multiple nonspecific ileal ulcers were observed. A pathological examination indicated a small granuloma with CD68-positive histiocytes. He had a deeply wrinkled forehead, chiseled face, and clubbed fingers. Radiography revealed periostosis of the fingers and long bones in the limb. He was diagnosed with pachydermoperiostosis. SLCO2A1 demonstrated a c.1807C>T homo-mutation. He was also diagnosed with SLCO2A1-associated chronic enteropathy and thus was treated with 5-aminosalicylic acid, which temporarily improved the ileal ulcers, anemia, and hypoalbuminemia.

Primary hypertrophic osteoarthropathy related gastrointestinal complication has distinctive clinical and pathological characteristics: two cases report and review of the literature

BACKGROUND

Primary hypertrophic osteoarthropathy (PHO) is a rare disease related to HPGD and SLCO2A1 gene mutation. Gastrointestinal involvement of PHO is even rarer with unknown pathogenesis. Clinical features of GI complication in PHO mimics other auto-immune based bowel entities, such as inflammatory bowel diseases and cryptogenic multifocal ulcerous stenosing enteritis (CMUSE). We aimed to analyze the clinical, genetic, radiological and pathological features of Chinese patients with PHO and determine the difference between PHO patients presenting with and without GI involvement.

METHODS

We reported two PHO cases with gastrointestinal involvement and reviewed all the studies of PHO in Chinese population published from January 1, 2000, to April 30, 2018. Clinical and genetic presentations of PHO in Chinese patients were analyzed. We compared the characteristics of those patients with gastrointestinal involvement against those without.

RESULTS

The two patients were both males with complete-form PHO for more than 10 years. GI related symptoms included diarrhea, chronic gastrointestinal hemorrhage, incomplete intestinal obstruction, anemia, and edema, which were unresponsive to etoricoxib treatment. Radiological examinations revealed segmental intestinal stenosis and thickened intestinal wall. Endoscopic findings included multiple ulcers and mucosal inflammation. Both patients had mutations of SLCO2A1 according to sequence analysis. The surgical pathology revealed chronic inflammation involving the intestinal mucosa and submucosa, similar to histological changes in CMUSE. According to the systemic review of 158 Chinese patients with PHO, 17.2% had gastrointestinal involvement, including peptic ulcer, gastric polyps, hypertrophic gastritis, and segmental intestinal stenosis. Patients with gastrointestinal involvement were more likely to have anemia (40.0% vs. 4.5%, P < 0.001), hypoalbuminemia (16.7% vs. 0.9%, P = 0.003), and myelofibrosis (19.0% vs. 0.9%, P = 0.002) than those without. Most patients with gastrointestinal complication had SLCO2A1 mutation (86.7%, 13 /15).

CONCLUSIONS

Digestive tract involvement is uncommon in patients with PHO and often presents with anemia, and hypoalbuminemia resulted from intestinal inflammation. The intestinal pathologic characteristics are distinct from Crohn's disease but similar to CMUSE. Mutations in SLCO2A1 might be the pathogenic cause of GI involvement of PHO. NSAIDs may not be effective for PHO patients with gastrointestinal complications.

Novel SLCO2A1compound heterozygous mutation causing primary hypertrophic osteoarthropathy with Bartter-like hypokalemia in a Chinese family

PURPOSE

Primary hypertrophic osteoarthropathy (PHO) is an inherited disease characterized by digital clubbing, periostosis and pachydermia with defects in the degradation of prostaglandin E2 (PGE2). Mutations in SLCO2A1 gene-encoding prostaglandin transporter (PGT) resulted in PHO, autosomal recessive 2 (PHOAR2). The spectrum of mutations and variable clinical complications of PHOAR2 has been delineated. In this study, we investigated a Chinese PHO family with a manifestation of Bartter-like hypokalemia.

METHODS

Clinical manifestations were collected and genetic analyses were performed in the PHO family.

RESULTS

The 33-year-old male proband had severe hypokalemia due to potassium loss from the kidney, while his brother had mild hypokalemia. After being treated with etoricoxib, the serum potassium level of the patient increased rapidly to the normal range which corresponded with the reduction in his serum PGE2 and PE2 metabolite (PGEM) levels. A novel SLCO2A1 compound heterozygous mutation of p.I284V and p.C459R was identified in two PHO patients in this family.

CONCLUSIONS

The present findings supported that the Bartter-like hypokalemia is a new complication of PHOAR2 caused by the high level of PGE2. Etoricoxib was demonstrated to be effective for the renal hypokalemia in PHO patients.