Danggui Buxue Tang Attenuates Tubulointerstitial Fibrosis via Suppressing NLRP3 Inflammasome in a Rat Model of Unilateral Ureteral Obstruction.

Inflammation significantly contributes to the progression of chronic kidney disease (CKD). This study aimed to characterize Danggui Buxue Tang (DBT) renoprotection and relationship with NOD-like receptors family pyrin domain-containing 3 (NLRP3) inflammasome expression in rats with unilateral ureteral obstruction (UUO). Sprague-Dawley rats were subjected to UUO and randomly assigned to untreated UUO, enalapril-treated (10 mg/kg/day), and DBT-treated (9 g/kg/day) groups. Sham-operated rats served as controls, with 8 rats in each group. All rats were sacrificed for blood and renal specimen collection at 14 days after UUO. Untreated UUO rats exhibited azotemia, intense tubulointerstitial collagen deposition, upregulations of tubulointerstitial injury index, augmentation levels of collagen I (Col I), α-smooth muscle actin (α-SMA), NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase-1, caspase-1, IL-1ß, and pro-IL-1ß. DBT treatment significantly attenuated interstitial collagen deposition and tubulointerstitial injury, lowering Col I and α-SMA levels. Synchronous expressions of NLRP3, ASC, pro-caspase-1, caspase-1, pro-IL-1ß, and IL-1ß decreased in renal tissue. In comparison to enalapril, DBT significantly reduced tubulointerstitial injury, interstitial collagen deposition, and expressions of Col I and IL-1ß. Thus, DBT offers renoprotection in UUO rats, which was associated with suppressing NLRP3 inflammasome expression and following reduction of the secretion of cytokine IL-1ß. The mechanisms of multitargets of traditional Chinese medicine can be better used for antifibrotic treatment.

Antagonism of scavenger receptor CD36 by 5A peptide prevents chronic kidney disease progression in mice independent of blood pressure regulation.

Scavenger receptor CD36 participates in lipid metabolism and inflammatory pathways important for cardiovascular disease and chronic kidney disease (CKD). Few pharmacological agents are available to slow the progression of CKD. However, apolipoprotein A-I-mimetic peptide 5A antagonizes CD36 in vitro. To test the efficacy of 5A, and to test the role of CD36 during CKD, we compared wild-type to CD36 knockout mice and wild-type mice treated with 5A, in a progressive CKD model that resembles human disease. Knockout and 5A-treated wild-type mice were protected from CKD progression without changes in blood pressure and had reductions in cardiovascular risk surrogate markers that are associated with CKD. Treatment with 5A did not further protect CD36 knockout mice from CKD progression, implicating CD36 as its main site of action. In a separate model of kidney fibrosis, 5A-treated wild-type mice had less macrophage infiltration and interstitial fibrosis. Peptide 5A exerted anti-inflammatory effects in the kidney and decreased renal expression of inflammasome genes. Thus, CD36 is a new therapeutic target for CKD and its associated cardiovascular risk factors. Peptide 5A may be a promising new agent to slow CKD progression.

Effect of salvianolic acid A and C compatibility on inflammatory cytokines in rats with unilateral ureteral obstruction.

OBJECTIVE: To investigate the effect of salvianolic acid A and C component molecules, which are involved in drug compatibility, on inflammatory cytokine expression that affects human chemokine ligand 5 (CCL5) and chemokine ligand 10 (CXCL10) levels in rats with unilateral ureteral obstruction (UUO). METHODS: Fifty Sprague Dawley rats were randomly divided into five groups: normal, model, salvianolic acid A, salvianolic acid C and salvianolic acid A and C groups. The normal group was used as the control, and the other groups of rats had a UUO model established. The control group had free access to food and water, and the other groups received the corresponding drugs for 2 weeks. After the last administration, urine ß2-microglobulin (ß 2-MG) and N-acetyl-ß-D-glucosaminidase (NAG) levels were analyzed. After 24 h, all rats were sacrificed and the serum was analyzed for creatinine (Cr) and blood urea nitrogen (BUN) levels. Rat kidneys were removed, and CCL5 and CXCL10 inflammatory cytokine mRNA expression was measured using real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR). Kidney fibrosis was observed using hematoxylin-eosin (HE) staining and Masson trichrome staining. RESULTS: In the salvianolic acid A and salvianolic acid C treatment groups, serum Cr and urine NAG levels were significantly lower than in the model group (both P < 0.05). In all treatment groups, urine ß2-MG levels were significantly lower than in the model group (all P < 0.05). Compared with model group, the pathological changes and collagen deposition improved to varying degrees (both P < 0.05). CCL5 and CXCL10 mRNA expression decreased to different degrees compared with the model group (both P < 0.05). CONCLUSION: Salvianolic acid A and C are component molecules of drug compatibility, and they may protect renal function and improve tubular function and renal pathology to a certain degree in UUO. This improvement may be related to a reduction in inflammatory cytokines CCL5 and CXCL10 secretion in the UUO rat kidney.

HMGB1 exacerbates renal tubulointerstitial fibrosis through facilitating M1 macrophage phenotype at the early stage of obstructive injury.

Previous studies have indicated that macrophage phenotype diversity is involved in the progression of renal fibrosis. However, the factors facilitating M1 or M2 phenotypes and the function of these polarized macrophages in kidney injury and fibrosis remain largely unknown. In the present study, we found that macrophages accumulated in the kidney interstitium exhibited mainly as the M1 phenotype at the early stage of unilateral ureter obstruction (UUO). High-mobility group box 1 (HMGB1) protein expressed and released from tubular epithelial cells and interstitial macrophages was essential for the M1 macrophage transition. HMGB1 significantly induced the expression of the M1 marker inducible nitric oxide synthase while decreasing the M2 marker IL-10 in macrophages. Moreover, a glycyrrhizic acid derivative, a blocker of HMGB1 release, reduced UUO-mediated kidney injury and ameliorated UUO-induced renal fibrosis. Interestingly and importantly, UUO caused a low pH value in the urine accumulated in the obstructed ureter, and the acidified urine induced HMGB1 release from tubular epithelial cells and macrophages in vitro. Our data demonstrate that HMGB1 is an essential contributor in facilitating M1 polarization at the early stage of UUO. Inhibition of HMGB1 release may alter macrophage phenotype and contribute to the protection of kidney tissue from injury and fibrosis.