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.

Effect of acute iNOS inhibition on glomerular function in tubulointerstitial nephritis.

BACKGROUND: Tubulointerstitial nephritis (TIN) is characterized by progressive inflammatory infiltrate of the renal interstitium, induction of cortical tubular inducible nitric oxide synthase (iNOS) and reductions in glomerular filtration rate (GFR). These studies were designed to examine the changes in glomerular hemodynamics 7 and 21 days after induction of TIN and to evaluate the effect of acute iNOS blockade on glomerular function in the early stages of this model. METHODS: TIN was induced by immunizing Brown Norway rats with renal tubular antigen in complete Freund's adjuvant (RTA/CFA). Control rats were immunized with CFA alone. Micropuncture and morphologic studies were performed 7 and 21 days after immunization. RESULTS: Histology revealed minimal peritubular and interstitial inflammation in the RTA/CFA group one week after immunization while extensive interstitial inflammation with few preserved superficial nephron was observed three weeks after RTA/CFA immunization. Micropuncture studies on day 7 in the RTA/CFA group revealed a significant reduction in single nephron GFR due to a profound reduction in nephron plasma flow and in the ultrafiltration coefficient. Studies performed on day 21 revealed that single nephron GFR (SNGFR), nephron plasma flow (SNPF) and the ultrafiltration coefficient had returned to the normal baseline value despite the severe reduction in GFR. To assess the role of increased nitric oxide production secondary to iNOS induction on the glomerular hemodynamic changes observed in the early stages of the disease, the iNOS blocker (l-N(6)-iminoethyl lysine, L-NIL) was administered IV (1 mg/h) in RTA/CFA rats and CFA rats. L-NIL had no effect in CFA rats but produced significant increases in GFR, SNGFR and SNPF in RTA/CFA rats. CONCLUSIONS: These results demonstrate that TIN is associated with a progressive reduction in GFR, which is likely the result of functional vasoconstriction and decreases in the ultrafiltration coefficient in the early stages of the disease and on a significant reduction in the number of functioning nephron in the later stages. Induction of iNOS with increased NO production actively participates in the functional changes observed in the early stages of the disease most likely by inhibiting normal endothelial NOS activity.

Suppression of experimental autoimmune tubulointerstitial nephritis in BALB/c mice by berberine.

Berberine (BB) is a protoberberine alkaloid derived from various representatives of the Berberidaceae family. Although used as a therapeutic agent, it has not been applied in the treatment of immune-mediated disorders. In the present study, BB was administered at a daily dose of 10 mg/kg for 3 consecutive days before the induction of tubulointerstitial nephritis (TIN) by injection of bovine tubular basement membrane (TBM) antigen in BALB/c mice. The animals were investigated 2 months after TBM inoculation. The intensity of pathological injuries in animals with TIN+BB decreased significantly, an effect that correlated with the improvement of renal function. Flow cytometric analysis of peripheral blood cells showed that BB caused a decrease in the number of CD3(+), CD4(+), CD8(+), and sIg(+) lymphocytes in comparison with TIN mice. The same tendency was noticed in the lymphocytes from kidney infiltrates of treated animals. The control animals treated only with BB showed a decrease in the number of CD3(+), CD4(+), CD8(+) T-lymphocytes in comparison with control nontreated mice. Our results, thus, indicate that BB has an immunosuppressive effect in the TIN model, which is an analogue of various human kidney autoimmune diseases.

High water intake ameliorates tubulointerstitial injury in rats with subtotal nephrectomy: possible role of TGF-beta.

BACKGROUND: It has been shown that tubulointerstitial injury correlates well with a decline of renal function. In this study, we investigated the effect of high water intake (HWI) on functional and structural parameters in rats with subtotal nephrectomy. METHODS: Two weeks after the ablative procedure, rats were divided into two groups. One group received the treatment with HWI (3% sucrose added to drinking water) for eight weeks. Functional parameters were compared with sham-operated control (CONT) or nephrectomized rats without treatment (NX). Remnant kidneys were then assessed histologically for evidence of interstitial fibrosis and glomerulosclerosis. RESULTS: Creatinine clearance was significantly improved in HWI rats compared with NX rats. Simultaneously, urinary protein was also significantly reduced in HWI rats. HWI predominantly ameliorated interstitial lesions and, to a lesser extent, glomerular lesions. Northern blot analysis demonstrated that transforming growth factor-beta (TGF-beta) mRNA expression was significantly suppressed in HWI rats. In situ hybridization revealed that HWI suppressed TGF-beta mRNA expression mainly in the outer medulla. Fibronectin mRNA was also reduced by the HWI treatment. The changes in TGF-beta and fibronectin mRNA were in parallel with Na+/myo-inositol cotransporter (SMIT) mRNA, which is regulated by extracellular osmolarity. Immunohistochemistry demonstrated that protein expression of TGF-beta and fibronectin coincided with the mRNA expression. CONCLUSION: These results suggest that HWI reduces TGF-beta mRNA expression in medullary interstitium and ameliorates tubulointerstitial injury in rats with reduced renal mass.

Inhibition of inducible nitric oxide synthase intensifies injury and functional deterioration in autoimmune interstitial nephritis.

T lymphocytes are exquisitely sensitive to the antiproliferative effects of nitric oxide. We examined the effects of oral administration of two nitric oxide synthase inhibitors, Nw-nitro-L-arginine methyl ester (L-NAME) and L-N6-(1-iminoethyl)lysine (L-NIL), on the course of T cell-dependent autoimmune interstitial nephritis in Brown Norway rats. Kidneys from rats immunized to produce interstitial nephritis display a net generation of nitric oxide end products. By immunohistochemical staining, the cytokine-inducible nitric oxide synthase (iNOS) is expressed in cortical tubular epithelial cells. Treatment with either inhibitor results in markedly more severe disease following immunization. Animals receiving L-NAME were hypertensive, while those treated with L-NIL, a highly selective inhibitor of iNOS, were not. Evaluation of the expression of IFN-gamma, IL-2, and IL-4 in diseased kidneys by quantitative reverse transcriptase-PCR demonstrated that L-NAME-treated animals displayed significantly augmented levels of IFN-gamma and IL-2 with preserved ratios of IFN-gamma/IL-4 and IL-2/IL-4, while L-NIL-treated animals had augmented levels of IL-2 and IFN-gamma with augmented IFN-gamma/IL-4 and IL-2/IL-4 ratios. Animals treated with L-NAME or L-NIL both had augmented Ag-specific IgG responses. The L-NAME group demonstrated increases in both the IgG2a and IgG1 subtypes, with a constant IgG2a/IgG1 ratio, while the L-NIL group demonstrated an increase in the ratio of the IgG2a/IgG1 response. These Ab and cytokine data suggest that the L-NIL-treated animals had a skewing of their immune response toward a Th1-like response. We conclude that in autoimmune interstitial nephritis, generation of nitric oxide through the iNOS pathway has host-protective effects, and suggest that this may be broadly applicable to T cell-mediated pathologies.