Decreased Expression of DRA (SLC26A3) by a p38 Driven IL-1α Response Contributes to Diarrheal Disease Following In vivo Challenge with Brachyspira spp.

In this study, we uncovered the novel mechanism of IL-1α-mediated DRA (SLC26A3) downregulation in the context of Brachyspira spp. induced malabsorptive diarrhea. Experimentally infected pigs with Brachyspira spp. had significantly reduced DRA expression in the colon accompanied by IL-1α upregulation. This response was recapitulated in vitro by exposing Caco-2 cells to either Brachyspira lysate or IL-1α. Both p38 and MK-2 showed an increased phosphorylation after exposure to either. SB203580 application, a p38 inhibitor blocked the MK-2 phosphorylation and attenuated the DRA and IL-1α response to both lysate and IL-1α. Exposure to IL-1 receptor antagonist (IL-1RA) produced a similar response. Additionally, exposure of cells to either of these blockers without IL-1α or lysate results in increased DRA and decreased IL-1α expression, revealing that DRA needs IL-1α signalling for basal physiological expression. Dual inhibition with both blockers completely inhibited the effect from IL-1α while significantly attenuating the response from Brachyspira lysate, suggesting a minor contribution from another pathway. Together this demonstrates that Brachyspira activates p38 MAPK signalling driving IL-1α expression which activates IL-1R1 causing DRA downregulation. While also driving upregulation of IL-1α through p38 in a positive feedback mechanism. In conclusion we elucidated a major pathway involved in DRA downregulation and its role in Brachyspira induced diarrhea. Additionally these observations will aid in our understanding of other inflammatory and infectious diarrhea conditions.

The anion exchanger slc26a3 regulates colonic mucus expansion during steady state and in response to prostaglandin E2, while Cftr regulates de novo mucus release in response to carbamylcholine.

The intestinal epithelium is covered by mucus that protects the tissue from the luminal content. Studies have shown that anion secretion via the cystic fibrosis conductance regulator (Cftr) regulates mucus formation in the small intestine. However, mechanisms regulating mucus formation in the colon are less understood. The aim of this study was to explore the role of anion transport in the regulation of mucus formation during steady state and in response to carbamylcholine (CCh) and prostaglandin E2 (PGE2). The broad-spectrum anion transport inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS), CftrdF508 (CF) mice, and the slc26a3 inhibitor SLC26A3-IN-2 were used to inhibit anion transport. In the distal colon, steady-state mucus expansion was reduced by SLC26A3-IN-2 and normal in CF mice. PGE2 stimulated mucus expansion without de novo mucus release in wild type (WT) and CF colon via slc26a3 sensitive mechanisms, while CCh induced de novo mucus secretion in WT but not in CF colon. However, when added simultaneously, CCh and PGE2 stimulated de novo mucus secretion in the CF colon via DIDS-sensitive pathways. A similar response was observed in CF ileum that responded to CCh and PGE2 with DIDS-sensitive de novo mucus secretion. In conclusion, this study suggests that slc26a3 regulates colonic mucus expansion, while Cftr regulates CCh-induced de novo mucus secretion from ileal and distal colon crypts. Furthermore, these findings demonstrate that in the absence of a functional Cftr channel, parallel stimulation with CCh and PGE2 activates additional anion transport processes that help release mucus from intestinal goblet cells.

Diagnóstico prenatal de clorhidrorrea congénita: reporte de caso / Prenatal diagnosis of congenital chloride diarrhea: A case report

La clorhidrorrea congénita es un trastorno genético infrecuente pero importante caracterizado por una alteración grave del balance hidroelectrolítico como resultado de un defecto en la absorción intestinal de cloruros. Los niños afectados presentan diarrea persistente, deshidratación y malnutrición; el control médico y del desarrollo son complejos. Mejorar la detección prenatal es esencial para facilitar la atención del paciente, las intervenciones tempranas y el asesoramiento genético informado. Sin embargo, a pesar de los avances de la medicina, la naturaleza compleja y la escasa frecuencia de esta entidad, constituyen un desafío para la detección prenatal. En este estudio, se reporta el caso de una embarazada donde los estudios por imágenes de resonancia magnética fetales identificaron en forma efectiva las características típicas de la clorhidrorrea congénita. Se proveen conocimientos sobre las complejidades del diagnóstico y se sugieren caminos para las estrategias de detección temprana de esta enfermedad.

Congenital chloride diarrhea (CCD) is a rare but significant genetic disorder characterized by severe electrolyte imbalances resulting from impaired intestinal chloride absorption. Affected children experience persistent diarrhea, dehydration, and malnutrition, complicating medical and developmental care. The enhancement of prenatal detection is crucial for improved patient management, early interventions, and informed genetic counseling. However, despite advancements in medicine, the complex nature and rarity of CCD make prenatal detection challenging. In this study, we report a fetal case where prenatal magnetic resonance imaging (MRI) effectively identified the distinctive characteristics of CCD, providing insights into the complexities of diagnosis and suggesting avenues for enhanced early detection strategies.

Ion Transport Basis of Diarrhea, Paneth Cell Metaplasia, and Upregulation of Mechanosensory Pathway in Anti-CD40 Colitis Mice.

BACKGROUND: Anti-Cluster of differentiation (CD)-40-induced colitis, driven by innate inflammatory responses in the intestine, is a potent animal model exhibiting IBD pathophysiology including diarrhea. However, the ion transport basis of diarrhea and some key mucosal pathways (Paneth cells, stem cell niche, and mechanosensory) in this model have not been investigated. METHODS: Mucosal scrapings and intestinal tissue from control and CD40 antibody (150 µg) treated Rag2-/- mice were examined for gut inflammation, Paneth cell numbers, expression of key transporters, tight/adherens junction proteins, stem cell niche, and mechanosensory pathway via hematoxylin and eosin staining, quantitative polymerase chain reaction, and western blotting. RESULTS: Compared with control, anti-CD40 antibody treatment resulted in a significant loss of body weight (P < .05) and diarrhea at day 3 postinjection. Distal colonic tissues of anti-CD40 mice exhibited increased inflammatory infiltrates, higher claudin-2 expression, and appearance of Paneth cell-like structures indicative of Paneth cell metaplasia. Significantly reduced expression (P < .005) of downregulated in adenoma (key Cl- transporter), P-glycoprotein/multidrug resistantance-1 (MDR1, xenobiotic transporter), and adherens junction protein E-cadherin (~2-fold P < .05) was also observed in the colon of anti-CD40 colitis mice. Interestingly, there were also marked alterations in the stem cell markers and upregulation of the mechanosensory YAP-TAZ pathway, suggesting the activation of alternate regeneration pathway post-tissue injury in this model. CONCLUSION: Our data demonstrate that the anti-CD40 colitis model shows key features of IBD observed in the human disease, hence making it a suitable model to investigate the pathophysiology of ulcerative colitis (UC).

Our studies demonstrate the ion transport basis of diarrhea, downregulation of MDR1 and E-cadherin, Paneth cell metaplasia, and induction of claudin-2 and mechanosensory pathway in anti-CD40 colitis (innate immune-based model of IBD), similar to the human disease.

Bicarbonate secretion and acid/base sensing by the intestine.

The transport of bicarbonate across the enterocyte cell membrane regulates the intracellular as well as the luminal pH and is an essential part of directional fluid movement in the gut. Since the first description of "active" transport of HCO3- ions against a concentration gradient in the 1970s, the fundamental role of HCO3- transport for multiple intestinal functions has been recognized. The ion transport proteins have been identified and molecularly characterized, and knockout mouse models have given insight into their individual role in a variety of functions. This review describes the progress made in the last decade regarding novel techniques and new findings in the molecular regulation of intestinal HCO3- transport in the different segments of the gut. We discuss human diseases with defects in intestinal HCO3- secretion and potential treatment strategies to increase luminal alkalinity. In the last part of the review, the cellular and organismal mechanisms for acid/base sensing in the intestinal tract are highlighted.

Prenatal diagnosis of congenital chloride diarrhea: A case report. / Diagnóstico prenatal de clorhidrorrea congénita: reporte de caso.

Congenital chloride diarrhea (CCD) is a rare but significant genetic disorder characterized by severe electrolyte imbalances resulting from impaired intestinal chloride absorption. Affected children experience persistent diarrhea, dehydration, and malnutrition, complicating medical and developmental care. The enhancement of prenatal detection is crucial for improved patient management, early interventions, and informed genetic counseling. However, despite advancements in medicine, the complex nature and rarity of CCD make prenatal detection challenging. In this study, we report a fetal case where prenatal magnetic resonance imaging (MRI) effectively identified the distinctive characteristics of CCD, providing insights into the complexities of diagnosis and suggesting avenues for enhanced early detection strategies.

La clorhidrorrea congénita es un trastorno genético infrecuente pero importante caracterizado por una alteración grave del balance hidroelectrolítico como resultado de un defecto en la absorción intestinal de cloruros. Los niños afectados presentan diarrea persistente, deshidratación y malnutrición; el control médico y del desarrollo son complejos. Mejorar la detección prenatal es esencial para facilitar la atención del paciente, las intervenciones tempranas y el asesoramiento genético informado. Sin embargo, a pesar de los avances de la medicina, la naturaleza compleja y la escasa frecuencia de esta entidad, constituyen un desafío para la detección prenatal. En este estudio, se reporta el caso de una embarazada donde los estudios por imágenes de resonancia magnética fetales identificaron en forma efectiva las características típicas de la clorhidrorrea congénita. Se proveen conocimientos sobre las complejidades del diagnóstico y se sugieren caminos para las estrategias de detección temprana de esta enfermedad.

SLC26A3 (DRA) is stimulated in a synergistic, intracellular Ca2+-dependent manner by cAMP and ATP in intestinal epithelial cells.

In polarized intestinal epithelial cells, downregulated in adenoma (DRA) is an apical Cl-/[Formula: see text] exchanger that is part of neutral NaCl absorption under baseline conditions, but in cyclic adenosine monophosphate (cAMP)-driven diarrheas, it is stimulated and contributes to increased anion secretion. To further understand the regulation of DRA in conditions mimicking some diarrheal diseases, Caco-2/BBE cells were exposed to forskolin (FSK) and adenosine 5'-triphosphate (ATP). FSK and ATP stimulated DRA in a concentration-dependent manner, with ATP acting via P2Y1 receptors. FSK at 1 µM and ATP at 0.25 µM had minimal to no effect on DRA given individually; however, together, they stimulated DRA to levels seen with maximum concentrations of FSK and ATP alone. In Caco-2/BBE cells expressing the Ca2+ indicator GCaMP6s, ATP increased intracellular Ca2+ (Ca2+i) in a concentration-dependent manner, whereas FSK (1 µM), which by itself did not significantly alter Ca2+i, followed by 0.25 µM ATP produced a large increase in Ca2+ that was approximately equal to the elevation caused by 1 µM ATP. 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM) pretreatment prevented the ATP and FSK/ATP synergistically increased the DRA activity and the increase in Ca2+i caused by FSK/ATP. FSK/ATP synergistic stimulation of DRA was similarly observed in human colonoids. In Caco-2/BBE cells, subthreshold concentrations of FSK (cAMP) and ATP (Ca2+) synergistically increased Ca2+i and stimulated DRA activity with both being blocked by BAPTA-AM pretreatment. Diarrheal diseases, such as bile acid diarrhea, in which both cAMP and Ca2+ are elevated, are likely to be associated with stimulated DRA activity contributing to increased anion secretion, whereas separation of DRA from Na+/H+ exchanger isoform-3 (NHE3) contributes to reduced NaCl absorption.NEW & NOTEWORTHY The BB Cl-/[Formula: see text] exchanger DRA takes part in both neutral NaCl absorption and stimulated anion secretion. Using intestinal cell line, Caco-2/BBE high concentrations of cAMP and Ca2+ individually stimulated DRA activity, whereas low concentrations, which had no/minimal effect, synergistically stimulated DRA activity that required a synergistic increase in intracellular Ca2+. This study increases understanding of diarrheal diseases, such as bile salt diarrhea, in which both cAMP and elevated Ca2+ are involved.

The Air-Liquid Interface Reorganizes Membrane Lipids and Enhances the Recruitment of Slc26a3 to Lipid-Rich Domains in Human Colonoid Monolayers.

Cholesterol-rich membrane domains, also called lipid rafts (LRs), are specialized membrane domains that provide a platform for intracellular signal transduction. Membrane proteins often cluster in LRs that further aggregate into larger platform-like structures that are enriched in ceramides and are called ceramide-rich platforms (CRPs). The role of CRPs in the regulation of intestinal epithelial functions remains unknown. Down-regulated in adenoma (DRA) is an intestinal Cl-/HCO3- antiporter that is enriched in LRs. However, little is known regarding the mechanisms involved in the regulation of DRA activity. The air-liquid interface (ALI) was created by removing apical media for a specified number of days; from 12-14 days post-confluency, Caco-2/BBe cells or a colonoid monolayer were grown as submerged cultures. Confocal imaging was used to examine the dimensions of membrane microdomains that contained DRA. DRA expression and activity were enhanced in Caco-2/BBe cells and human colonoids using an ALI culture method. ALI causes an increase in acid sphingomyelinase (ASMase) activity, an enzyme responsible for enhancing ceramide content in the plasma membrane. ALI cultures expressed a larger number of DRA-containing platforms with dimensions >2 µm compared to cells grown as submerged cultures. ASMase inhibitor, desipramine, disrupted CRPs and reduced the ALI-induced increase in DRA expression in the apical membrane. Exposing normal human colonoid monolayers to ALI increased the ASMase activity and enhanced the differentiation of colonoids along with basal and forskolin-stimulated DRA activities. ALI increases DRA activity and expression by increasing ASMase activity and platform formation in Caco-2/BBe cells and by enhancing the differentiation of colonoids.

Oxalate secretion is stimulated by a cAMP-dependent pathway in the mouse cecum.

Elevated levels of the intracellular second messenger cAMP can stimulate intestinal oxalate secretion however the membrane transporters responsible are unclear. Oxalate transport by the chloride/bicarbonate (Cl-/HCO3-) exchanger Slc26a6 or PAT-1 (Putative Anion Transporter 1), is regulated via cAMP when expressed in Xenopus oocytes and cultured cells but whether this translates to the native epithelia is unknown. This study investigated the regulation of oxalate transport by the mouse intestine focusing on transport at the apical membrane hypothesizing PAT-1 is the target of a cAMP-dependent signaling pathway. Adopting the Ussing chamber technique we measured unidirectional 14C-oxalate and 36Cl- flux ([Formula: see text] and [Formula: see text]) across distal ileum, cecum and distal colon, employing forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) to trigger cAMP production. FSK/IBMX initiated a robust secretory response by all segments but the stimulation of net oxalate secretion was confined to the cecum only involving activation of [Formula: see text] and distinct from net Cl- secretion produced by inhibiting [Formula: see text]. Using the PAT-1 knockout (KO) mouse we determined cAMP-stimulated [Formula: see text] was not directly dependent on PAT-1, but it was sensitive to mucosal DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid), although unlikely to be another Cl-/HCO3- exchanger given the lack of trans-stimulation or cis-inhibition by luminal Cl- or HCO3-. The cAMP-activated oxalate efflux was reliant on CFTR (Cystic Fibrosis Transmembrane conductance Regulator) activity, but only in the presence of PAT-1, leading to speculation on the involvement of a multi-transporter regulatory complex. Further investigations at the cellular and molecular level are necessary to define the mechanism and transporter(s) responsible.

Vitamin D receptor involves in the protection of intestinal epithelial barrier function via up-regulating SLC26A3.

BACKGROUND: Vitamin D receptor (VDR) and SLC26A3 (DRA) have been identified as pivotal protective factors in maintaining gut homeostasis in IBD patients. However, the specific mechanism underlying the increased intestinal susceptibility to inflammation induced by the loss of VDR and whether DRA participates in the role of VDR regulating intestinal epithelial barrier function are undefined. AIM: The current study is undertaken to elucidate the regulatory effects of VDR on DRA and VDR prevents intestinal epithelial barrier dysfunction via up-regulating the expression of DRA. METHODS: WT and VDR-/- mice are used as models for intestinal epithelial response. Paracellular permeability is measured by TEER and FD-4 assays. Immunohistochemistry, immunofluorescence, qPCR and immunoblotting are performed to determine the effects of VDR and DRA on gut epithelial barrier function. RESULTS: VDR-/- mice exhibits significant hyperpermeability of intestine with greatly decreased levels of ZO-1 and Claudin1 proteins. DRA is located on the intestinal epithelial apical membrane and is tightly modulated by VDR in vivo and in vitro via activating ERK1/2 MAPK signaling pathway. Notably, the current study for the first time demonstrates that VDR maintains intestinal epithelial barrier integrity via up-regulating DRA expression and the lack of DRA induced by VDR knockdown leads to a more susceptive condition for intestine to DSS-induced colitis. CONCLUSION: Our study provides evidence and deep comprehension regarding the role of VDR in modulating DRA expression in gut homeostasis and makes novel contributions to better generally understanding the links between VDR, DRA and intestinal epithelial barrier function.

Gene/environment interaction in the susceptibility of Crohn's disease patients to aluminum.

BACKGROUND & AIM: The key role of environmental factors in the pathogenesis of Inflammatory Bowel Diseases (IBD) is recognized. Aluminum is suspected to be a risk factor for IBD. However, mechanisms linking aluminum exposure to disease development are unknown. We examined the role of aluminum transport and subcellular localisation on human colon susceptibility to aluminum-induced inflammation. METHODS: Human colon biopsies isolated from Crohn's disease (CD) or control patients and Caco-2 cells were incubated with aluminum. The effects of aluminum were evaluated on cytokine secretion and transporter expression. The role of aluminum kinetics parameters was studied in Caco-2 using transport inhibitors and in human colon biopsies by assessing genetic polymorphisms of transporters. RESULTS: Aluminum exposure was shown to induce cytokine secretion in colon of CD but not healthy patients. In Caco-2 cells, aluminum internalisation was correlated with inflammatory status. In human colon, analysis of genetic polymorphisms and expression of ABCB1 and SLC26A3 transporters showed that their decreased activity was involved in aluminum-induced inflammation. CONCLUSIONS: We hypothesize that alteration in detoxifying response would lead to a deregulation of intestinal homeostasis and to the expression of IBD. Our study emphasizes the complexity of gene/environment interaction for aluminum adverse health effect, highlighting at risk populations or subtypes of patients. A better understanding of correlations between gene expression or SNP and xenobiotic kinetics parameters would shift the medical paradigm to more personalized disease management and treatment.

Segmental maternal uniparental disomy of chromosome 7q in a patient with congenital chloride diarrhea.

BACKGROUND: The main symptoms of congenital chloride diarrhea (CCD) main symptoms are watery diarrhea, hypochloremia, and hypokalemic metabolic alkalosis. Silver-Russell syndrome (SRS) is a heterogeneous imprinting disorder characterized by severe intrauterine retardation, poor postnatal growth, and facial dysmorphism. METHODS: Parent-offspring trio whole-exome sequencing was used to identify the causal variants. Sequencing reads were mapped to the reference of human genome version hg19. Sanger sequencing was performed as a confirmatory experiment. RESULTS: The proband was a patient with SRS caused by maternal uniparental disomy 7. The CCD of the proband was caused by homozygous variant c.1515-1 (IVS13) G>A; both mutated alleles were inherited from her mother. CONCLUSION: We report the first clinical case of CCD and SRS occurring together. Patients with milder phenotypes may be difficult to diagnose in early stage, but close monitoring of potential complications is important for identification.

SATB2 Defect Promotes Colitis and Colitis-associated Colorectal Cancer by Impairing Cl-/HCO3- Exchange and Homeostasis of Gut Microbiota.

BACKGROUND: SATB2 is a diagnostic biomarker and a favourable prognostic marker for colorectal cancer [CRC], but its role in colitis and colitis-associated colorectal cancer [CAC] is unknown. METHODS: Colitis was induced in intestinal epithelial-specific Satb2 knockout [Satb2 IEC-KO] and control mice using dextran sulphate sodium [DSS]. RNA-seq analysis was performed on colonic tissues, and 16S rDNA-Seq on faecal bacterial DNA from Satb2 IEC-KO and control mice. Immunohistochemistry and flow cytometry were performed to reveal the proportions of different immune cells. Chromatin immunoprecipitation [ChIP] and luciferase reporter were applied to show the regulatory role of SATB2 on SLC26A3, of which the Cl-/HCO3- exchange activity was measured fluorometrically by the pHi-sensitive dye. Bacteroides were detected by fluorescence in situ hybridisation [FISH] on colonic tissue. RESULTS: Satb2 IEC-KO mice suffered from intestinal epithelial damage spontaneously, and developed more severe colitis and CAC. The expression of SLC26A3 correlated well with SATB2 revealed by RNA-seq and The Cancer Genome Atlas [TCGA] data, and was governed by SATB2 confirmed by ChIP and luciferase reporter experiments. Decreased intestinal flora diversity was seen in Satb2 IEC-KO mice. Bacteroides were more abundant and could colonise into the inner layer of colonic mucosa in Satb2 IEC-KO mice. Faecal microbiome transplantation from Satb2 IEC-KO mice aggravated colitis and M1 macrophages infiltration. CONCLUSIONS: SATB2 plays a vital role in maintaining intestinal homeostasis, and its deficiency promotes the development of colitis and CAC by influencing the intestinal luminal environment and gut flora.

Inflammatory Bowel Disease in Patients with Congenital Chloride Diarrhoea.

BACKGROUND: Congenital chloride diarrhoea [CLD] is a rare autosomal recessive disease caused by mutations in the solute family carrier 26 member 3 [SLC26A3] gene. Patients suffer from life-long watery diarrhoea and chloride loss. Inflammatory bowel disease [IBD] has been reported in individual patients with CLD and in scl26a3-deficient mice. METHODS: We performed an international multicentre analysis to build a CLD cohort and to identify cases with IBD. We assessed clinical and genetic characteristics of subjects and studied the cumulative incidence of CLD-associated IBD. RESULTS: In a cohort of 72 patients with CLD caused by 17 different SLC26A3 mutations, we identified 12 patients [17%] diagnosed with IBD. Nine patients had Crohn's disease, two ulcerative colitis and one IBD-unclassified [IBD-U]. The prevalence of IBD in our cohort of CLD was higher than the highest prevalence of IBD in Europe [p < 0.0001]. The age of onset was variable [13.5 years, interquartile range: 8.5-23.5 years]. Patients with CLD and IBD had lower z-score for height than those without IBD. Four of 12 patients had required surgery [ileostomy formation n = 2, ileocaecal resection due to ileocaecal valve stenosis n = 1 and colectomy due to stage II transverse colon cancer n = 1]. At last follow-up, 5/12 were on biologics [adalimumab, infliximab or vedolizumab], 5/12 on immunosuppressants [azathioprine or mercaptopurine], one on 5-ASA and one off-treatment. CONCLUSIONS: A substantial proportion of patients with CLD develop IBD. This suggests the potential involvement of SL26A3-mediated anion transport in IBD pathogenesis. Patients with CLD-associated IBD may require surgery for treatment failure or colon cancer.

Congenital chloride diarrhea in patient with SLC26A2 mutation - analysis of the clinical phenotype and differential diagnosis.

INTRODUCTION: To analyze the clinical features and SLC26A3 mutation of one patient in our hospital who had congenital loss of chlorine diarrhea (CLD), and to investigate the treatment of the disease and the prognosis. MATERIAL AND METHODS: By reviewing the literature, analyzing the clinical features and differential diagnosis and investigating the treatment and prognosis, the patient was diagnosed as CLD. RESULTS: Excessive accumulation of amniotic fluid was observed during pregnancy. The patient was born prematurely with normal body weight. The patient was a 4-month old boy admitted for anorexia, watery diarrhea, electrolyte disorders (hyponatremia, hypokalemia and hypochloremia) and metabolic alkalosis. The patient was also considered to be affected by Batter syndrome. After treating with spironolactone, indomethacin and potassium chloride sustained release tablet, the symptom of watery diarrhea was alleviated, the ingested amount of milk increased gradually and the amount of urine became normal; however, electrolyte imbalance persisted and the frequency of bowel movements remained high. Genetic analysis demonstrated that the patient had a SLC26A3 c.269_270dupAA homozygous mutation in exon 3, leading to a frameshift from 91st amino acid Gly and alteration of the SLC26A3 transmembrane protein sequence, thus resulting in a Cl-/HCO3- exchange barrier. The parents of the patient had normal phenotypes and were all heterozygous carriers of the mutation. Moreover, the patient was diagnosed as CLD. Sodium chloride and potassium chloride rather than spironolactone and indomenthacin were given to the patient to correct the dehydration, so the symptom of watery diarrhea alleviated and the blood gas and electrolyte levels returned to the normal range. In addition, the patients morale was good and the ingested amount of milk was moderate. CONCLUSIONS: Persistent diarrhea and electrolyte disorder in pediatrics are easy to misdiagnose as CLD. Furthermore, it is difficult to identify Batter syndrome, Gitelman syndrome, renal tubular acidosis and CLD. Blood and stool electrolyte detection and SLC26A3 genetic tests are helpful for diagnosis, and sodium chloride and potassium chloride replacement therapy are critical for the patient prognosis.

Step-Up Approach for Sodium Butyrate Treatment in Children With Congenital Chloride Diarrhea.

OBJECTIVES: Oral salt substitutive therapy is pivotal for the survival of patients with congenital chloride diarrhea (CLD), however this therapy is unable to influence the symptoms severity. Butyrate has been proposed to limit diarrhea severity in CLD. Unfortunately, the optimal dose schedule is still largely undefined. In addition, butyrate seems not to be well-tolerated by all patients, with some subjects reporting diarrhea worsening. We investigated the efficacy of a step-up therapeutic approach with sodium butyrate in patients who experienced a diarrhea worsening or an absent improvement after the direct administration of 100 mg/kg/day of sodium butyrate. METHODS: The efficacy of a step-up therapeutic approach starting from 50 mg/Kg/day with a subsequent 25 mg/kg/day weekly increase up to 100 mg/kg/day of oral sodium butyrate was investigated in previously three unresponsive CLD children. RESULTS: The step-up therapeutic approach resulted effective in limiting diarrhea severity in all our three previously unresponsive CLD patients. CONCLUSIONS: Our results suggest the efficacy of the step-up therapeutic approach in CLD children.

Prenatal and Postnatal Manifestations of Congenital Chloride Diarrhea Due to a Heterozygote Variant of the SLC26A3 Gene: A Case Report.

Congenital chloride diarrhea (CCD) is caused by a recessive mutation in the SLC26A3 gene and characterized mainly by watery diarrhea, hypochloremia and metabolic alkalosis. Various different mutations in SLC26A3 are responsible for the disease. In the prenatal period, the symptoms of CCD may include polyhydramnios, preterm labor and abdominal distension. The main feature of CCD is chloride-rich diarrhea, which leads to excessive loss of fluid and salt immediately after birth and is followed by weight loss and dehydration. Hyponatremia and hypochloremia are soon accompanied by hypokalemia and metabolic alkalosis. Untreated CCD is fatal even in the first weeks of life. Diagnosis is made by high fecal chloride concentrations in patients with serum electrolytes corrected by salt substitution and confirmed using genetic testing of peripheral blood samples. Here, we detail prenatal and postnatal manifestations of a preterm infant, born via Caesarian section, who was suspected to suffer intrauterine bowel obstruction. Upper median laparotomy was performed and no intestinal abnormalities found. The course of the neonatal period was complicated by severe diarrhea with hypochloremia, hyponatremia and metabolic alkalosis. Based on the patient's clinical picture and stool examination, a diagnosis of CCD was established. Mutation of the SLC26A3 gene was confirmed using genetic testing.

Slc26a3 (DRA) in the Gut: Expression, Function, Regulation, Role in Infectious Diarrhea and Inflammatory Bowel Disease.

BACKGROUND: The transport of transepithelial Cl- and HCO3- is crucial for the function of the intestinal epithelium and maintains the acid-based homeostasis. Slc26a3 (DRA), as a key chloride-bicarbonate exchanger protein in the intestinal epithelial luminal membrane, participates in the electroneutral NaCl absorption of intestine, together with Na+/H+ exchangers. Increasing recent evidence supports the essential role of decreased DRA function or expression in infectious diarrhea and inflammatory bowel disease (IBD). METHOD: In this review, we give an overview of the current knowledge of Slc26a3, including its cloning and expression, function, roles in infectious diarrhea and IBD, and mechanisms of actions. A better understanding of the physiological and pathophysiological relevance of Slc26a3 in infectious diarrhea and IBD may reveal novel targets for future therapy. CONCLUSION: Understanding the physiological function, regulatory interactions, and the potential mechanisms of Slc26a3 in the pathophysiology of infectious diarrhea and IBD will define novel therapeutic approaches in future.

Congenital chloride diarrhea in patient with SLC26A2 mutation - analysis of the clinical phenotype and differential diagnosis.

INTRODUCTION: To analyze the clinical features and SLC26A3 mutation of one patient in our hospital who had congenital loss of chlorine diarrhea (CLD), and to investigate the treatment of the disease and the prognosis. MATERIAL AND METHODS: By reviewing the literature, analyzing the clinical features and differential diagnosis and investigating the treatment and prognosis, the patient was diagnosed as CLD. RESULTS: Excessive accumulation of amniotic fluid was observed during pregnancy. The patient was born prematurely with normal body weight. The patient was a 4-month old boy admitted for anorexia, watery diarrhea, electrolyte disorders (hyponatremia, hypokalemia and hypochloremia) and metabolic alkalosis. The patient was also considered to be affected by Batter syndrome. After treating with spironolactone, indomethacin and potassium chloride sustained release tablet, the symptom of watery diarrhea was alleviated, the ingested amount of milk increased gradually and the amount of urine became normal; however, electrolyte imbalance persisted and the frequency of bowel movements remained high. Genetic analysis demonstrated that the patient had a SLC26A3 c.269_270dupAA homozygous mutation in exon 3, leading to a frameshift from 91st amino acid Gly and alteration of the SLC26A3 transmembrane protein sequence, thus resulting in a Cl-/HCO3- exchange barrier. The parents of the patient had normal phenotypes and were all heterozygous carriers of the mutation. Moreover, the patient was diagnosed as CLD. Sodium chloride and potassium chloride rather than spironolactone and indomenthacin were given to the patient to correct the dehydration, so the symptom of watery diarrhea alleviated and the blood gas and electrolyte levels returned to the normal range. In addition, the patients morale was good and the ingested amount of milk was moderate. CONCLUSIONS: Persistent diarrhea and electrolyte disorder in pediatrics are easy to misdiagnose as CLD. Furthermore, it is difficult to identify Batter syndrome, Gitelman syndrome, renal tubular acidosis and CLD. Blood and stool electrolyte detection and SLC26A3 genetic tests are helpful for diagnosis, and sodium chloride and potassium chloride replacement therapy are critical for the patient prognosis.

Colonic delivery of vasoactive intestinal peptide nanomedicine alleviates colitis and shows promise as an oral capsule.

Aim: To evaluate the efficacy of locally delivered nanomedicine, vasoactive intestinal peptide in sterically stabilized micelles (VIP-SSM) to the colon and conduct in vitro release studies of a potential oral formulation. Materials & methods: Intracolonic instillation of VIP-SSM was tested in a mouse model of dextran sulfate sodium-induced colitis. Based on the effective mouse dose, human equivalent dose containing nanomedicine powder was filled into enteric coated capsules for in vitro release testing. Results: Colonic delivery of VIP-SSM significantly alleviated colitis. VIP-SSM containing capsules completely dissolved at colonic pH allowing micelles to reform with active VIP. Capsule formulations exhibited reproducible release profiles when stored up to 6 weeks demonstrating stability. Conclusion: VIP-SSM is an effective nanomedicine formulation which appears to have potential for oral treatment of colitis in humans. [Formula: see text].