Knockdown of histone deacetylase 1 in fibroblasts and pericytes prevents renal interstitial fibrosis after ischemia-reperfusion injury

University of Alabama at Birmingham

Ischemia-reperfusion injury (IRI) happens when there is a decline in blood flow through the kidney. This injury can lead to the formation of interstitial fibrosis. We published that within an hour of bilateral IRI, in male mice, there was an increase of histone deacetylase 1 (HDAC1) in the epithelium and interstitialcells. Moreover, inhibition of HDAC1 prior to IRI resulted in attenuated interstitial fibrosis. We hypothesized that the knockdown of HDAC1 in fibroblasts and pericytes, which differentiate into myofibroblasts, will attenuate interstitial fibrosis in the kidney after IRI. Male control(HDAC1fl/fl) and iFibroblastHDAC1KO (HDAC1fl/fl, Col1A2-CreER, hemizygous mice) were used. The mice underwent bilateral renal pedicle clamping for 18 minutes to induce IRI or sham surgery. Reduced kidney function was confirmed by serum creatinine measurements and determination of glomerular filtration rate (GFR) by transcutaneous FITC-sinistrin clearance 24 hours after injury. Renal interstitial fibrosis was quantified by measuring the percentage coverage area of collagen stained by picrosirius red staining. 24 hours after surgery, IRI mice serum creatinine levels were greater in control mice 0.53 mg/dl ± 0.17, n = 9, and iFibHDAC1KO IRI mice 0.25 mg/dl ± 0.053, n = 10, compared to sham mice. This agreed with the measured GFR that was significantly reduced 50% in the IRI mice. The collagen-positive area was significantly higher in control than in sham mice (p = 0.0011), while there wasno noticeable difference (p = 0.9) between iFibHDAC1KO and sham mice (control IRI = 1.2 % ± 0.2, KO IRI = 0.47% ± 0.12, sham control = 0.35% ± 0.085, sham KO = 0.401% ± 0.073). HDAC1 overexpression in fibroblasts resulted in increased expression of pro-inflammatory cytokines/chemokines. In conclusion, fibroblast HDAC1 is activated by IRI and which likely involves crosstalk with infiltrating immune leading to interstitial fibrosis.