Explore the vast range of titles available.

The transcription factor Pax6 is an important regulator of development and cell differentiation in various organs. Thus, Pax6 was shown to promote neural development in the cerebral cortex and spinal cord, and to control pancreatic endocrine cell genesis. However, the role of Pax6 in distinct endocrine cells of the adult pancreas has not been addressed. We report the conditional inactivation of Pax6 in insulin and glucagon producing cells of the adult mouse pancreas. In the absence of Pax6, beta- and alpha-cells lose their molecular maturation characteristics. Our findings provide strong evidence that Pax6 is responsible for the maturation of beta-, and alpha-cells, but not of delta-, and PP-cells. Moreover, lineage-tracing experiments demonstrate that Pax6-deficient beta- and alpha-cells are shunted towards ghrelin marked cells, sustaining the idea that ghrelin may represent a marker for endocrine cell maturation.

The two compositionally distinct extracellular cochlear fluids, endolymph and perilymph, are separated by tight junctions that outline the scala media and reticular lamina. Mutations in TRIC (also known as MARVELD2), which encodes a tricellular tight junction protein known as tricellulin, lead to nonsyndromic hearing loss (DFNB49). We generated a knockin mouse that carries a mutation orthologous to the TRIC coding mutation linked to DFNB49 hearing loss in humans. Tricellulin was absent from the tricellular junctions in the inner ear epithelia of the mutant animals, which developed rapidly progressing hearing loss accompanied by loss of mechanosensory cochlear hair cells, while the endocochlear potential and paracellular permeability of a biotin-based tracer in the stria vascularis were unaltered. Freeze-fracture electron microscopy revealed disruption of the strands of intramembrane particles connecting bicellular and tricellular junctions in the inner ear epithelia of tricellulin-deficient mice. These ultrastructural changes may selectively affect the paracellular permeability of ions or small molecules, resulting in a toxic microenvironment for cochlear hair cells. Consistent with this hypothesis, hair cell loss was rescued in tricellulin-deficient mice when generation of normal endolymph was inhibited by a concomitant deletion of the transcription factor, Pou3f4. Finally, comprehensive phenotypic screening showed a broader pathological phenotype in the mutant mice, which highlights the non-redundant roles played by tricellulin.

The two compositionally distinct extracellular cochlear fluids, endolymph and perilymph, are separated by tight junctions that outline the scala media and reticular lamina. Mutations in TRIC (also known as MARVELD2), which encodes a tricellular tight junction protein known as tricellulin, lead to nonsyndromic hearing loss (DFNB49). We generated a knockin mouse that carries a mutation orthologous to the TRIC coding mutation linked to DFNB49 hearing loss in humans. Tricellulin was absent from the tricellular junctions in the inner ear epithelia of the mutant animals, which developed rapidly progressing hearing loss accompanied by loss of mechanosensory cochlear hair cells, while the endocochlear potential and paracellular permeability of a biotin-based tracer in the stria vascularis were unaltered. Freeze-fracture electron microscopy revealed disruption of the strands of intramembrane particles connecting bicellular and tricellular junctions in the inner ear epithelia of tricellulin-deficient mice. These ultrastructural changes may selectively affect the paracellular permeability of ions or small molecules, resulting in a toxic microenvironment for cochlear hair cells. Consistent with this hypothesis, hair cell loss was rescued in tricellulin-deficient mice when generation of normal endolymph was inhibited by a concomitant deletion of the transcription factor, Pou3f4. Finally, comprehensive phenotypic screening showed a broader pathological phenotype in the mutant mice, which highlights the non-redundant roles played by tricellulin.

BackgroundFaecal calprotectin (FCAL) rises rapidly in children with Crohn’s disease (CD) following treatment with exclusive enteral nutrition (EEN). We aimed to identify clinical, dietary and diet-related microbial metabolites which associate with the recurrence of FCAL above 250 mg/kg after 21 days of food reintroduction.MethodsChildren with CD (age 6–17 years), clinically responding to EEN, were recruited, prospectively, from 11 UK hospitals (January 2020-May 2023, NCT04225689). They provided a single faecal sample before EEN completion (timepoint A) and 6 serial samples (timepoints B-G; 3, 6, 9, 12, 15, 21 days) in the first 21 days of food reintroduction. Faecal short (SCFA) and branched (BCFA) chain fatty acids were measured as proxies of fibre and protein bacterial fermentation, respectively. In faeces, pH, water content (%), Bristol stool score, total microbial load (qPCR) and starch output were measured. Clinical parameters, medications, CRP, ESR, albumin and anthropometry were recorded at EEN completion. Nutrient and food group intake was analysed with Nutritics®. Relationships with FCAL levels were explored.Results Thirty children provided 209/210 (99%) of expected faecal samples. FCAL (median [Q1, Q3], mg/kg) increased within 12 days of food reintroduction (EEN completion: 328 [154, 2370] vs 12 days post-EEN: 1123 (451, 2073), p<0.01) and remained high throughout follow-up. Negative correlations were observed between FCAL with acetate, whereas positive correlations were noted with BCFA (isovalerate and isobutyrate) and their ratio over acetate; the latter remained significant at all 7 timepoints (figure 1A). Use of immunosuppressants, blood inflammatory markers, clinical and anthropometry at EEN completion were not predictive of FCAL increase post-EEN.In a subset of patients with FCAL<250 mg/kg at EEN completion, (n=13/30), subset regression using ‘end of EEN’ diet-related microbial data, generated a model with 91% accuracy to predict FCAL increase over 250 mg/kg at 21 days of food reintroduction, with isovalerate being the sole predictor of FCAL recurrence (figure 1B). Average intake of cereal products (median [Q1, Q3], g/day) over 21 days was lower in patients who experienced an FCAL recurrence (FCAL<250mg/kg: 313 (223, 370) vs FCAL>250mg/kg: 186 (167, 217), p=0.013). Positive correlations were observed between the 21-day average intake of cereal products and concentration of SCFA at 21 days post-EEN; acetate (rho=0.38, p=0.041), butyrate (rho=0.46, p=0.0.01) and total SCFA (rho=0.41, p=0.026).ConclusionsThis study suggests that early FCAL rebound, following treatment with EEN, is related to an increased ratio of dietary protein to fibre bacterial fermentation and a lower intake of cereal products.Abstract OC2 Figure 1(A): Correlations between faecal parameters and FCAL at EEN completion (Time-point A) and food reintroduction (Time-points B-G) after adjustment for multiple comparisons (Benjamini-Hochberg). (B): Subset regression analysis using end-of-EEN data to predict FCAL recurrence (FCAL>250mg/kg at day 21)

BackgroundExclusive enteral nutrition (EEN) is a main therapy for active Crohn’s disease (CD) in children, but normalisation of faecal calprotectin (FCAL) varies among patients, even in those who enter clinical remission. To better understand disease characteristics related to EEN efficacy and its mechanism of action, we compared clinical and microbial parameters between patients whose FCAL normalised against those who did not at EEN completion.MethodsChildren with CD, clinically responding to EEN, were recruited from 11 UK hospitals (January 2020- May 2023, NCT04225689) and provided a single faecal sample before EEN completion. Patients were divided in two groups according to levels of FCAL at EEN completion (FCAL<250 and FCAL>250 mg/kg). Levels of faecal short chain fatty acids (SCFA), faecal sample characteristics (pH, water content (%), bristol stool score) and total microbial load (qPCR) were compared between the two groups. Anthropometric and clinical parameters (blood inflammatory markers, use of immunosuppressants, disease duration, disease location) were also compared. Machine learning using feature elimination with data imputation for missing data was performed to identify associations between clinical, anthropometry, microbial parameters and FCAL normalisation.ResultsAt EEN completion, 84 children (female, 35%) were recruited [age, median (IQR): 13.2 (11.8, 14.9 years)] with a median (Q1, Q3) FCAL of 643 (146, 2033) mg/kg. Out of 84 patients, 35 (42%) had an FCAL<250 mg/kg. Total microbial load and SCFA were measured in a subset of patients (n=44). Patients with FCAL<250mg/kg had a higher faecal pH and lower microbial load compared to those with FCAL>250mg/kg [faecal pH; FCAL<250 mg/kg: 8.3 (8.1, 8.6) vs FCAL>250 mg/kg; 7.95 (7.6, 8.3), p=0.001; microbial load (log10 16S rRNA gene copies/g): FCAL<250mg/kg: 10.7 (10.4, 10.9) vs FCAL>250mg/kg: 11.0 (10.5, 11.2), p=0.02]. Median BMI z-score was also non-significantly (p=0.052) higher in patients with FCAL<250mg/kg. The use of immunosuppressants at EEN completion, disease duration, disease location and other faecal parameters were not different between the two groups. A multicomponent random forest model (clinical, blood inflammatory markers, anthropometry, faecal parameters) predicted normalisation of FCAL with 71% accuracy (sensitivity: 69%, specificity: 71%, p=<0.001, figure 1). Higher faecal pH, BMI z-scores and lower total microbial load were the most influential parameters relating to FCAL<250mg/kg.ConclusionsWe showed that the efficacy of EEN in reducing gut inflammation might be, at least in part, mediated via reducing gut bacterial biomass and modulating luminal pH and the downstream effects this may have on inflammatory members of the microbial community.Abstract OC1 Figure 1(A) Random forest (RF) classification between FCAL responders and non-responders using clinical, anthropometry and microbial data. (B): Area under the curve of the best RF model. (C): Barplots of categorical variables included in RF model