Figure 2.

TUDCA protects the tubular compartment in db/db mice via FXR. (A) TUDCA (T) reduces albuminuria (ΔUACR; reflecting the fold change of albuminuria from baseline) in db/db mice as compared with PBS-treated control mice (db). This effect is largely abolished by Z-guggulsterone (T+Gu) or in vivo knockdown of FXR using morpholino (T+FXR-MO). (B and C) TUDCA (T) reduces (B) extracellular matrix accumulation (fractional mesangial area [FMA]) and (C) glomerular diameter (Glom. diameter) in db/db treated mice as compared with PBS-treated control mice (db). Concomitant treatment with Z-guggulsterone (T+Gu) or in vivo knockdown of FXR using morpholino (T+FXR-MO) does not impede TUDCA-mediated improvement of glomerular injury markers. (D and E) TUDCA (T) reduces (D) tubular diameter (Tub. diameter) and (E) KIM-1 expression (bottom: representative immunoblots), reflecting tubular injury, in db/db mice as compared with PBS-treated control mice (db). This effect is largely abolished by concomitant Z-guggulsterone treatment (T+Gu) or in vivo knockdown of FXR using morpholino (T+FXR-MO). (F) Representative histologic sections (PAS staining) showing glomerular and tubular morphology in db/db control mice (db), db/db mice with TUDCA (T), db/db mice with concomitant TUDCA and Z-guggulsterone (T+Gu) treatment, or TUDCA treatment paralleled by in vivo knockdown of FXR using morpholino (T+FXR-MO). (G) Expression of inflammatory (IL-6, TNF-α) and fibrotic (collagen 1α2) markers is reduced in TUDCA-treated (T) db/db mice as compared with PBS-treated db/db control mice (db). This effect is abrogated by concomitant treatment with Z-guggulsterone (T+Gu). Representative RT-PCR images (bottom) and bar graph summarizing results. Bar graphs reflecting mean±SEM (A–E and G) of at least six mice per group (number of mice per group: db, 15; T, 13; T+Gu, 12; T+FXR-MO, 6); scale bar, 20 μm (F); *P<0.05; **P<0.01; ***P<0.001 (one-way ANOVA).