The impact of the epithelial-mesenchymal transition (EMT) to the formation of renal fibrosis has been debated in several lineage-tracing studies, with conflicting findings. Such disparities may have arisen from varying experimental conditions such as different disease models, the mouse strain, and type of genetic alteration used. In order to determine the contribution of these factors to EMT, we generated four kidney disease models in several mouse strains genetically modified to express enhanced green fluorescence protein (EGFP) in cortical tubular epithelial cells under the control of the γ-glutamyl transpeptidase promoter. Using this approach, the EMT was visible and quantifiable based on a count of EGFP-positive interstitial cells in the fibrotic kidney sections of the four renal disease models found to be either EMT-prone or -resistant. The EMT-prone models consisted of unilateral ureteral obstruction and ischemic nephropathy in SJL mice. The EMT-resistant models consisted of ureteral obstruction in C57B/6 and F1(C57B/6 × SJL) mice, adriamycin nephrosis in 129 mice, and nephrotoxic serum nephritis in SJL mice. Analyses of these renal disease models suggest the emergence of EMT-derived fibroblasts arises in a disease-specific and strain-dependent manner. Thus, when considering molecular mechanisms and involvement of the EMT in renal fibrosis, it is important to take into account the experimental conditions, particularly the mouse strain and type of disease model.

It is not clear whether interstitial fibroblasts or tubular epithelial cells are primarily responsible for the profibrotic effects of NF-κB activation during renal fibrogenesis. Here, we crossed mice carrying a conditional IκB dominant-negative transgene (IκBdN) with mice transgenic for cell-specific FSP1.Cre (FSP1⁺ fibroblasts) or γGT.Cre (proximal tubular epithelia) and challenged all progeny with unilateral ureteral obstruction. We determined NF-κB activation by nuclear localization of phosphorylated p65 (^pp65) in renal tissues after 7 days. We observed inhibition of NF-κB activation in interstitial cells and tubular epithelia in obstructed kidneys of FSP1.Cre;IκBdN and γGT.Cre;IκBdN mice, respectively, compared with IκBdN controls (P < 0.05). Deposition of extracellular matrix, however, was significantly lower in the obstructed kidneys of FSP1.Cre;IκBdN mice but not in γGT.Cre;IκBdN mice (P < 0.05). In addition, levels of mRNA encoding the profibrotic PAI-1, fibronectin-EIIIA, and type I (α1) procollagen were significantly lower in obstructed kidneys of FSP1.Cre;IκBdN mice compared with γGT.Cre;IκBdN mice (P < 0.05). Taken together, these data support a profibrotic role for fibroblasts, but not proximal tubular epithelial cells, in modulating NF-κB activation during renal fibrogenesis.

Background Several randomized controlled trials (RCTs) have demonstrated the cardiometabolic effects of aerobic exercise in the general population and in patients with cardiovascular diseases. However, the efficacy of aerobic exercise in patients with chronic kidney disease (CKD) remains to be elucidated. Methods RCTs comparing aerobic exercise with no aerobic exercise in patients with CKD not requiring kidney replacement therapy were identified through PubMed using RobotAnalyst, a web-based software system that combines text-mining and machine learning algorithms for organizing references. Cardiometabolic and renal outcomes of interest included body mass index (BMI); systolic blood pressure (SBP); hemoglobin A1c (HbA1c), total cholesterol (TCHO), low- and high- density lipoprotein cholesterol (LDLC and HDLC, respectively), and urinary protein (UP) levels/concentration; peak oxygen uptake (Vo₂peak); and glomerular filtration rate (GFR) at the end of the follow-up period. The standardized mean difference (SMD) of each outcome was estimated using the DerSimonian-Laird random-effect model with inverse-variance weighting. Results A total of 15 trials, including 622 patients, were included. Their follow-up periods were 3–4, 6–12, and > 12-months in 7 (46.7%), 7 (46.7%), and 1 (6.7%) trial(s), respectively. Meta-analyses showed that aerobic exercise significantly decreased BMI (SMD, -0.19 [95% confidence interval, −0.38, −0.00]) and SBP (−0.75 [−1.24, −0.26]) and increased Vo₂peak (0.54 [0.29, 0.78]); however, no significant association was observed in HbA1c, TCHO, HDLC, LDLC, GFR, and UP. Meta-regression models suggested that aerobic exercise was more likely to improve Vo₂peak in patients with younger age, no diabetes, and lower BMI. Conclusion Aerobic exercise of 3–12 months’ duration improved obesity, high blood pressure, and low exercise capacity in overweight/obese patients with CKD, but it had no significant effect on GFR and proteinuria. Well-designed large RCTs with a longer follow-up period are needed to evaluate the efficacy of aerobic exercise in patients with CKD.