The anti-inflammatory properties of green tea extract protect against gentamicin-induced kidney injury.

We assessed in vivo the protective effects and underlying antioxidant and anti-inflammatory properties of dry green tee extract (GTE) on glomerular and tubular kidney function and structure in an experimental model of gentamicin (GEN)-induced nephrotoxicity. Wistar rats were divided into four groups and treated daily for 10 days. The control group received distilled water; the GTE group received 20 µg/g body weight (BW) GTE by gavage; the GEN group received 100 mg/g BW GEN intraperitoneally; and the GEN+GTE group received GTE and GEN simultaneously, as described above. At the beginning and end of treatment, the serum creatinine, fractional excretion of sodium and potassium, and plasma heme oxygenase (HO)-1 levels and oxidative stress (OS) were assessed. At the end of the experiment, kidney fragments were collected for histological evaluation and immunohistochemical studies of cyclooxygenase (COX)-2 and nuclear factor (NF)kB. The levels of interleukin (IL)-1b, IL-4, IL-6, IL-10 and monocyte chemotactic protein (MCP)-1 were measured in kidney tissue. The results showed that GTE attenuated significantly kidney structural injury and prevented GEN-induced kidney functional injury (glomerular and tubular function). GTE significantly attenuated the kidney tissue increase of the proinflammatory mediators NF-kB, COX2, IL-1b and MCP-1 and significantly increased the kidney expression of the anti-inflammatory cytokines IL-6 and IL-10. However, GTE did not prevent OS increase in GEN-treated animals. In conclusion, GTE protected against GEN nephrotoxicity, likely due to direct blockade of the inflammatory cascade, which might had occurred independently of its antioxidant effect.

Pharmacological treatment with galectin-1 protects against renal ischaemia-reperfusion injury.

Galectin-1 protein (GAL-1) has important anti-inflammatory properties, but related pharmacologic approaches to effectively treat or prevent renal ischaemia and reperfusion injury are highly limited. Here, we investigated the effect of GAL-1 in a renal ischaemia-reperfusion injury rat model and an in vitro hypoxia-reoxygenation model with a proximal renal tubular epithelial cell line. In vivo, pretreatment with GAL-1 attenuated the renal parameters changed by ischaemia-reperfusion/hypoxia-reoxygenation, with recovery of renal function, protecting against influx of leukocytes, cell death and oxidative stress. Ischaemia-reperfusion/hypoxia-reoxygenation was also associated with increased renal endogenous expression of GAL-1 and intercellular adhesion molecule 1 (ICAM-1) plus augmented levels of proinflammatory cytokines IL-1ß, TNF-α and MCP-1 and decreased anti-inflammatory IL-10 in urine, all of which were abrogated by GAL-1 treatment. In vitro studies demonstrated renal tubular epithelial cells as an important source of GAL-1 during hypoxia-reoxygenation and confirmed the protective effects of exogenous GAL-1 through downregulation of proinflammatory cytokine release by proximal renal tubular epithelial cells. Collectively, our findings confirm the important anti-inflammatory role of GAL-1 in kidney ischaemia and reperfusion injury and indicate its promising use as a therapeutic approach.

Previous exposure to cigarette smoke aggravates experimental cyclosporine-induced nephrotoxicity.

BACKGROUND/AIMS: The effects of cigarette smoke (CS) on cyclosporine (CsA)-induced nephrotoxicity are poorly studied. This study aims to assess the effects of previous exposure to CS on CsA nephrotoxicity. METHODS: Rats were either exposed to CS or sham (S) procedures for 10 min twice a day for 20 weeks. From the 16th to the 20th week, they received a low-salt diet. Beginning with the 17th week, they were given 2.5 mg/day CsA or vehicle (VH) for 3 weeks. The final groups were VH/CS, CsA/CS, VH/S, and CsA/S. On day 141, glomerular filtration rate (GFR), renal blood flow (RBF), renal vascular resistance (RVR), tubulointerstitial fibrosis, and CsA blood levels were measured and immunohistochemistry was analyzed for renal α-smooth muscle actin (SMA), nitrotyrosine, and vimentin. RESULTS: CsA decrease in GFR was enhanced by CS exposure. CsA associated with CS induced higher periglomerular α-SMA and renal nitrotyrosine expression. CsA decreased RBF, but increased RVR, tubulointerstitial fibrosis, and α-SMA and renal vimentin expression. These changes and the CsA blood levels were not affected by CS exposure. CONCLUSION: CS aggravated the CsA-induced impairment of GFR and CS associated with CsA caused the development of periglomerular structural lesions and oxidative stress in a rat model of CsA nephrotoxicity.

Macrophage depletion attenuates chronic cyclosporine A nephrotoxicity.

BACKGROUND: Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by renal dysfunction and interstitial fibrosis. Early and progressive renal macrophage influx, correlating with latter interstitial fibrotic areas, has been associated with CsA treatment. This study investigated the role of macrophages, the nitric oxide (NO) pathway, and the oxidative stress on chronic CsA nephrotoxicity. METHODS: The macrophages were depleted by clodronate liposomes. Animals were distributed into four groups: vehicle (olive oil for 21 days), CsA 7.5 mg/kg per day (21 days), CsA plus clodronate (5 mg/mL intraperitoneally on days -4, 1, 4, 11, and 18 of CsA treatment), or vehicle plus clodronate. On day 22, glomerular filtration rate, renal blood flow, renal tubulointerstitial fibrosis, CsA blood levels, serum malondialdehyde and renal tissue immunohistochemistry for macrophages, inducible NO synthase, transforming growth factor-beta, nuclear factor-kbeta, alpha-smooth muscle actin, vimentin, and nitrotyrosine were assessed. RESULTS: CsA-induced increase in the macrophage was prevented by clodronate. Macrophage depletion attenuated the reductions in the glomerular filtration rate and renal blood flow, the development of tubulointerstitial fibrosis, malondialdehyde increase and increases in nuclear factor-kbeta, transforming growth factor-beta, vimentin, inducible NO synthase, and nitrotyrosine expression provoked by CsA. Clodronate did not affect alpha-smooth muscle actin expression and CsA blood levels. CONCLUSIONS: Renal macrophage influx plays an important role in CsA-induced chronic nephrotoxicity. The NO pathway and oxidative stress are likely mechanisms involved in the genesis of this form of renal injury.