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. Author manuscript; available in PMC: 2020 Mar 10.
Published in final edited form as: Gastroenterology. 2019 Nov 16;158(4):1000–1015. doi: 10.1053/j.gastro.2019.11.019

Figure 3. Leflunomide rescues abnormal intestinal features in ttc7a −/− zebrafish.

Figure 3.

(A) Histology from ttc7a −/− zebrafish (7 dpf) reveals pathological intestinal phenotypes. Control (ttc7a +/−) zebrafish display open luminal spaces with discernible villi projections (grey arrowhead), clefts (black arrowhead), monolayer epithelium (dotted-outlined area), and mature goblet cells with large vesicles (black arrows). ttc7a −/− zebrafish display narrowing of the intestinal bulb, stratified epithelium (yellow dotted-outlined area), signs of apoptosis (yellow arrows), and goblet cells with numerous small vesicles (yellow boxes). Objective magnification 10× and 40× for insets (scale bar 100 μm, inset scale bar 50 μm), (ttc7a +/− n=14, ttc7a −/− n=11). (B) Incidence of the narrow gut phenotype in DMSO and LEF treated fish. One-way ANOVA with post hoc test (Fisher’s LSD), ****p<0.0001, ttc7a +/− (DMSO n=49, LEF n=12), ttc7a −/− (DMSO n= 36, LEF n=26). (C) Intestinal histology from treated (see Methods) ttc7a−/− zebrafish. Leflunomide, cyanocobalamin and tiaprofenic acid suppressed the narrow-gut phenotype with minimal enterocyte crowding. Objective magnification 10×, (scale bar 100 μm). ttc7a+/− (DMSO n=49) ttc7a−/− (DMSO n= 36, CYANO n=10, LEF n=26, TIA n= 13, FEN n=13. (D) Assessment of apoptosis. DMSO or leflunomide treatment. ttc7a−/− zebrafish display fragmented, condensed or engulfed nuclei in the epithelium (arrows). Leflunomide treatment resulted in diminished signs of apoptosis, reduced intestinal epithelial cell crowding, and overall improved epithelium architecture in ttc7a−/− zebrafish. Refer to Supplementary Figure 7A for the quantitation of apoptotic cells/sample. Objective magnification 70× (scale bar 20 μm), (n=6 per group, across 3 experimental clutches). (E) Staining of the intestinal lumen in control (ttc7a+/−) and ttc7a-mutant (ttc7a−/−) zebrafish. Images are from peristalsis assays (Supplementary Video 2): intestinal lumen marked green fluorescent stain (DCFH-DA). ttc7a+/− fish have discernable villi (yellow arrow) and large continuous intestinal bulbs (double-headed white arrow). Representative ttc7a −/− intestinal phenotypes (i) atresia point (white arrow heads) (ii) narrow intestinal lumen and (iii) obstruction interrupting the intestinal bulb (white arrow). Objective magnification 4×, (scale bar 100 μm). (F) Incidence of ttc7a-mutant phenotypes. ttc7a−/− fish have significantly larger populations with motility and narrow lumen pathological phenotypes. Data are presented as the mean ±SD, one-way ANOVA with post hoc test (Fisher’s LSD), **p<0.0054, *p<0.0196, (n=50 total for each group, across 3 experimental clutches). (G) Phenotype summary from drug treated fish. ttc7a −/− fish with aberrant motility and narrow lumen phenotypes were significantly reduced with cyanocobalamin, leflunomide, tiaprofenic acid, and fenbufen treatment (3–7 dpf). Data are presented as the mean ±SD. Statistical significance was relative to ttc7a −/− DMSO control, and determined by two-way ANOVA with post hoc test (Dunnett), *p<0.05, **p<0.01, ***p<0.001, ns=not significant (DMSO n=18, CYANO n=21, LEF n=21, TIA n=17, FEN n=18, FAS n=13 for each group across 3 experimental clutches).