Fig. 1: The PYY-VIP axis regulates ion and water transport in mouse and human small intestine.
From: Enteroendocrine cells couple nutrient sensing to nutrient absorption by regulating ion transport
a PYY and VIP regulate ion and water transport in HIO-derived small intestinal enteroids. VIP-induced ion and water transport as measured by enteroid swelling (****P < 0.0001) in a CFTR-dependent manner. EEC-deficient enteroids had an elevated response to VIP compared to wild-type enteroids (*P = 0.04), which was inhibited in both cultures upon addition of PYY. Chemical inhibition of the PYY receptor NPY1R with BIBO3304 resulted in swelling of wild-type enteroids to EEC-deficient levels (****P < 0.0001) and abolished the inhibitory effects of PYY in both genotypes (****P < 0.0001). Scale bars = 500 μm. n = 283 wild-type, n = 351 EEC-deficient enteroids over three biologically independent lines. Statistics calculated by two-way ANOVA with Sidak’s multiple comparisons test; upper row indicates comparison to vehicle; lower row indicates comparison between wild-type and EEC-deficient. b EEC-deficient enteroids displayed impaired NHE3 activity. Quantification is of initial rate of Na+-dependent intracellular pH recovery (red line) after acid load using the ratiometric pH indicator SNARF-4F. n = 16 wild-type, n = 18 EEC-deficient enteroids; *P = 0.01; statistics calculated by unpaired, two-tailed Student’s t test. c The localization of VIPR1 and NPY1R was comparable between wild-type and EEC-deficient human intestinal epithelium. PYY+ and CHGA+ cells were only found in wild-type HIOs. Scale bars = 50 μm. Representative images from four independent organoids are shown. d PYY modulates the stimulatory effects of VIP in mouse and human small intestine. Using an Ussing chamber we observed EEC-deficient small intestinal tissue displayed a greater response (ΔIsc) to 10 nM VIP than wild-type (mouse, n = 20 wild-type, 8 mutant, ****P < 0.0001; human, n = 15 wild-type, 9 mutant, **P = 0.001). Inhibition of NPY1R in wild-type tissue with BIBO3304 resulted in an elevated response to VIP (mouse, n = 24, *P = 0.01; human, n = 7, *P = 0.04), whereas addition of exogenous PYY reduced the magnitude of EEC-deficient response to VIP (n = 8 mutant mice, ****P < 0.0001; n = 7 mutant HIOs, **P = 0.007) to wild-type levels. Electrogenic responses to VIP were blocked by the CFTR inhibitor CFTR-172 (dotted lines). One representative trace is shown (mouse), with baseline Isc normalized to 0 μA/cm2. Statistics calculated by one-way ANOVA with Tukey’s multiple comparisons test. All error bars are + SEM.
