Gentamicin induced apoptosis of renal tubular epithelial (LLC-PK1) cells

Exogenous glutathione protects against gentamicin-induced acute kidney injury by inhibiting NF-κB pathway, oxidative stress, and apoptosis and regulating PCNA

This study was designed, for the first time, to examine the possible nephroprotective effects of exogenous glutathione (EGSH) (100 mg/kg, intraperitoneally) on gentamicin-induced acute kidney injury (GM-induced AKI). EGSH reduced renal histopathological changes, inflammatory cell infiltration, and improved renal dysfunction in rats with AKI. EGSH ameliorated GM-induced renal oxidative stress by promoting the renal activities of catalase, glutathione peroxidase, and superoxide dismutase and diminishing renal malondialdehyde and serum nitric oxide levels. Interestingly, EGSH inhibited intrinsic apoptosis by downregulating Bax and caspase-3 and upregulating Bcl2 in the kidney of rats with AKI. EGSH decreased GM-induced inflammatory response as reflected by a remarkable decrease in the protein expressions of NF-κB-p65, IL-6, TNF-α, and iNOS and a considerable diminish in myeloperoxidase activity. Finally, EGSH markedly declined proliferative cell nuclear antigen (PCNA) protein expression in the animals with AKI. In summary, EGSH alleviated AKI in rats intoxicated with GM, partially by inhibiting oxidative stress, NF-κB pathway, and intrinsic apoptosis and regulating PCNA.

D-Limonene Alleviates Acute Kidney Injury Following Gentamicin Administration in Rats: Role of NF-κB Pathway, Mitochondrial Apoptosis, Oxidative Stress, and PCNA

Clinical application of gentamicin (GM) is well known to be associated with the development of acute kidney injury (AKI). This study was the first to investigate the possible protective effects of D-limonene (D-lim) on AKI following GM administration in rats. 32 rats arranged in four groups (n = 8): (1) the control group received saline intraperitoneally (0.5 ml/day) and orally (0.5 ml/day), (2) the D-lim group received D-lim (100 mg/kg) orally and saline (0.5 ml/day) intraperitoneally, (3) the GM group received GM (100 mg/kg/day) intraperitoneally and saline (0.5 ml/day) orally, and (4) the treated group received intraperitoneal GM (100 mg/kg) and oral D-lim (100 mg/kg). All treatments were performed daily for 12 consecutive days. Results revealed that D-lim ameliorated GM-induced AKI, oxidative stress, mitochondrial apoptosis, and inflammation. D-lim showed nephroprotective effects as reflected by the decrease in serum urea and creatinine and improvement of renal histopathological changes. D-lim alleviated GM-induced oxidative stress by increasing the activities of renal catalase, serum and renal glutathione peroxidase, and renal superoxide dismutase and decreasing renal malondialdehyde and serum nitric oxide levels. Intriguingly, D-lim suppressed mitochondrial apoptosis by considerably downregulating Bax and caspase-3 (Casp-3) mRNA and protein expressions and markedly enhancing Bcl2 mRNA and protein expressions. Furthermore, D-lim significantly decreases GM-induced inflammatory response through downregulation of NF-κB, IL-6, and TNF-α mRNA and/or protein expressions and decrease in renal myeloperoxidase activity. Finally, D-lim remarkably downregulated PCNA protein expression in the treated group compared with the GM group. In brief, this study showed that D-lim alleviated AKI following GM administration in rats, partially through its antioxidant, anti-inflammatory, and antiapoptotic activities as well as downregulation of PCNA expression.

Combinational effect of curcumin and metformin against gentamicin-induced nephrotoxicity: Involvement of antioxidative, anti-inflammatory and antiapoptotic pathway

Gentamicin (GM) is an antibiotic related to aminoglycoside group that is used in treating Gram-negative bacterial infections. However, treatment with gentamicin is considered to be limited as it induces an oxidative stress-mediated apoptosis in kidney which causes a nephrotoxicity. Metformin is a well-known biguanide that is used for treating diabetes mellitus, especially type 2. Supplement with plant metabolites or natural antioxidants produce a protective activity against many types of diseases in vivo. Curcumin is a main medicinal constituent of Curcuma longa, has reported for number of biological effects, such as antioxidant, anti-inflammatory, and antitumor. The study aims at evaluating the metformin and curcumin alone or in combination on nephrotoxicity induced by GM. The outcome of the study shows that both metformin and curcumin, when used unaided, were effectively decreasing GM-induced nephrotoxicity. The two drugs combination was showed synergistic effect in ameliorating a GM-induced kidney injury, as supported by expressively improved renal dysfunction. Metformin and curcumin showed strong protection against oxidative stress in GM treated animals through decreasing the activities and expression of various antioxidative enzymes. Moreover, combination of two drugs showed an anti-inflammatory response through reducing a level of pro-inflammatory cytokines including tumor necrosis factor-alpha, interleukin 1-beta, and interleukin 6 in GM intoxicated group of animals. Furthermore, GM agitated apoptosis was affectedly diminished by the combinational treatment of metformin and curcumin via down-regulating activity of cleaved Caspase-3 and pro-apoptotic factor Bax, whereas increasing anti-apoptotic factor Bcl-2 signaling pathways. The above results suggested that combinational treatment of metformin and curcumin might be have a synergizing effect and substantial potential against nephrotoxicity induced by GM. PRACTICAL APPLICATIONS: Curcumin and metformin combination exhibited substantial synergistic effect against GM-induced nephrotoxicity through reducing oxidative stress, inflammation, as well as apoptosis in kidney cells. Therefore, the method of combination of curcumin and metformin might be functional to treat or inhibit GM prompted nephrotoxicity in future.

Effects of Platelet-Rich Plasma on Kidney Regeneration in Gentamicin-Induced Nephrotoxicity

Platelet-rich plasma (PRP) as a source of growth factors may induce tissue repairing and improve fibrosis. This study aimed to assess the effects of PRP on kidney regeneration and fibrosis in gentamicin (GM)-induced nephrotoxicity rat model by stereological study. Thirty-two male rats were selected. Nephrotoxicity was induced in animals by administration of GM (80 mg/kg/daily, intraperitoneally [IP], 8 day) and animals were treated by PRP (100 μL, intra-cortical injection using surgical microscopy, single dose). Blood samples were collected for determine blood urea nitrogen (BUN) and creatinine (Cr) before and after PRP therapy. At the end of experiment, right kidneys were sectioned by Isotropic Uniform Random (IUR) method and stained with H & E and Masson's Trichrome. The stereological methods were used for estimating the changes in different structures of kidney. PRP increased the number of epithelial cells in convoluted tubules, and decreased the volume of connective tissue, renal corpuscles and glomeruli in GM-treated animals (P < 0.05). Our findings indicate that PRP had beneficial effects on proliferation of epithelial cells in convoluted tubules and ameliorated GM-induced fibrosis.

CCL2/CCR2 chemokine signaling coordinates survival and motility of breast cancer cells through Smad3 protein- and p42/44 mitogen-activated protein kinase (MAPK)-dependent mechanisms

Increased cell motility and survival are important hallmarks of metastatic tumor cells. However, the mechanisms that regulate the interplay between these cellular processes remain poorly understood. In these studies, we demonstrate that CCL2, a chemokine well known for regulating immune cell migration, plays an important role in signaling to breast cancer cells. We report that in a panel of mouse and human breast cancer cell lines CCL2 enhanced cell migration and survival associated with increased phosphorylation of Smad3 and p42/44MAPK proteins. The G protein-coupled receptor CCR2 was found to be elevated in breast cancers, correlating with CCL2 expression. RNA interference of CCR2 expression in breast cancer cells significantly inhibited CCL2-induced migration, survival, and phosphorylation of Smad3 and p42/44MAPK proteins. Disruption of Smad3 expression in mammary carcinoma cells blocked CCL2-induced cell survival and migration and partially reduced p42/44MAPK phosphorylation. Ablation of MAPK phosphorylation in Smad3-deficient cells with the MEK inhibitor U0126 further reduced cell survival but not migration. These data indicate that Smad3 signaling through MEK-p42/44MAPK regulates CCL2-induced cell motility and survival, whereas CCL2 induction of MEK-p42/44MAPK signaling independent of Smad3 functions as an alternative mechanism for cell survival. Furthermore, we show that CCL2-induced Smad3 signaling through MEK-p42/44MAPK regulates expression and activity of Rho GTPase to mediate CCL2-induced breast cancer cell motility and survival. With these studies, we characterize an important role for CCL2/CCR2 chemokine signaling in regulating the intrinsic relationships between breast cancer cell motility and survival with implications on the metastatic process.

Role of oxidative stress in lysosomal membrane permeabilization and apoptosis induced by gentamicin, an aminoglycoside antibiotic

Gentamicin, an aminoglycoside antibiotic used to treat severe bacterial infections, may cause acute renal failure. At therapeutic concentrations, gentamicin accumulates in lysosomes and induces apoptosis in kidney proximal tubular cells. In gentamicin-treated renal LLC-PK1 cells, acridine orange release from lysosomes, previously interpreted as lysosomal membrane permeabilization, precedes the apoptotic cascade that develops during incubation with gentamicin. However, the link between gentamicin lysosomal accumulation and apoptosis remains unclear. We here examined if reactive oxygen species (ROS) production could account for gentamicin-induced acridine orange release and apoptosis, and the implication of iron in these events. We found that gentamicin induced ROS production prior to, and at lower drug concentrations than required for, acridine orange release and apoptosis. ROS antioxidant or scavenger, catalase, and N-acetylcysteine largely prevented these events. Vital confocal imaging revealed that gentamicin-induced ROS production occurs in lysosomes. Deferoxamine, an iron chelator, which is endocytosed and accumulates in lysosomes, largely prevented gentamicin-induced ROS production as well as apoptosis. Direct evidence for gentamicin-induced permeabilization of lysosomal membrane was provided by showing the release into the cytosol of Lucifer yellow, a membrane-impermeant endocytic tracer with a comparable molecular weight as gentamicin. Altogether, our data demonstrate a key role of lysosomal iron and early ROS production in gentamicin-induced lysosomal membrane permeabilization and apoptosis.

Apoptosis induced by aminoglycosides in LLC-PK1 Cells: comparative study of neomycin, gentamicin, amikacin, and isepamicin using electroporation

Levels of apoptosis induction (4',6'-diamidino-2-phenylindole staining, activation of caspase 3) for aminoglycosides were compared by using renal LLC-PK1 cells. Amikacin caused less apoptosis than gentamicin in incubated cells. In electroporated cells, neomycin B and gentamicin caused apoptosis in the 0.03 to 0.1 mM range, isepamicin required larger concentrations (0.2 mM), and amikacin was without effect.

Glomerular nephrotoxicity of aminoglycosides

Aminoglycoside antibiotics are the most commonly used antibiotics worldwide in the treatment of Gram-negative bacterial infections. However, aminoglycosides induce nephrotoxicity in 10-20% of therapeutic courses. Aminoglycoside-induced nephrotoxicity is characterized by slow rises in serum creatinine, tubular necrosis and marked decreases in glomerular filtration rate and in the ultrafiltration coefficient. Regulation of the ultrafiltration coefficient depends on the activity of intraglomerular mesangial cells. The mechanisms responsible for tubular nephrotoxicity of aminoglycosides have been intensively reviewed previously, but glomerular toxicity has received less attention. The purpose of this review is to critically assess the published literature regarding the toxic mechanisms of action of aminoglycosides on renal glomeruli and mesangial cells. The main goal of this review is to provide an actualized and mechanistic vision of pathways involved in glomerular toxic effects of aminoglycosides.

Gentamicin treatment induces simultaneous mesangial proliferation and apoptosis in rats

BACKGROUND

Gentamicin (G)-induced acute renal failure is characterized by an impairment of glomerular function without apparent changes in glomerular structure. However, G stimulates reactive oxygen species (ROS)-mediated mesangial cell proliferation in vitro. We studied whether G promotes mesangial cell apoptosis in vitro, and if apoptosis and proliferation in parallel may occur in glomerular cells in vivo after a renal damage induced by G treatment.

METHODS

For in vivo studies, rats were treated with G (100 mg/kg body weight/day) for 6 days, and functional and histologic studies were performed. For in vitro studies, mesangial cell proliferation and apoptosis were evaluated after 24, 48, and 72 hours of 10(-5) mol/L G incubation.

RESULTS

After G injections, the number of nuclei per glomerulus did not change, whereas proliferating and apoptotic cell numbers increased. G increases DNA synthesis and cell number in cultured mesangial cells, and increases markedly the apoptotic cell number. ROS scavengers superoxide dismutase and catalase reduce G-induced mesangial cell apoptosis, whereas the incubation with the ROS donor system xanthine plus xanthine oxidase increases apoptosis to levels similar to G. G-induced cellular proliferation and apoptosis either in vitro or in vivo is associated to an early increase in the pro-apoptotic protein Bax and a delayed increase in the survival protein Bcl-2.

CONCLUSION

G simultaneously induces proliferation and apoptosis of mesangial cells in vitro and glomerular mesangial cells in vivo. ROS may mediate G-induced mesangial apoptosis in vitro. The equilibrium proliferation/apoptosis may maintain mesangial cell number within normal limits after a G-induced glomerular insult.

Gentamicin-induced hair cell death is not dependent on the apoptosis receptor Fas

OBJECTIVES/HYPOTHESIS

The hair cells are the most vulnerable elements in the cochlea, and damage to them is the most common cause of sensorineural hearing loss. Understanding the intracellular events that lead to the death of hair cells is a key to developing protective strategies. The Fas death receptor-mediated apoptotic pathway is well studied and plays an important role in the elimination of damaged cells in a number of different cellular systems. We have studied the role of the Fas receptor in aminoglycoside-mediated toxicity in vitro. We employed the MRL/MpJ-Fas mouse, which does not express a functional Fas receptor.

STUDY DESIGN

Response of Fas-deficient hair cells to gentamicin was compared with the response of normal hair cells in vitro.

METHODS

Basal turn organ of Corti explants from p3-5 mice were maintained in tissue culture and treated with gentamicin for 72 hours. The explants were fixed and were stained with phalloidin, and counting was performed.

RESULTS

There was no difference in hair cell loss between Fas mutant mice and control MRL/MpJ mice with a functional Fas receptor.

CONCLUSION

The gentamicin-mediated hair cell death is not dependent on a functional Fas receptor.

Effects of gentamicin, lipopolysaccharide, and contrast media on immortalized proximal tubular cells

Aminoglycosides are widely used in the treatment of gram-negative bacterial infections. Gentamicin (GE) acts mainly in proximal tubular cells, where it is uptake via organic anion transport system and it induces a high incidence of nephrotoxicity, which is characterized by tubular necrosis [5] leading to acute renal failure in 10 to 50% of patients. Gram-negative bacteria has lipopolysaccharide (LPS) which is an endotoxin that cause renal damage. [1] Moreover, many patients are undergone exams using radiologic contrast, which is a risk factor to induce a hemodynamic change in the kidney and to develop acute renal failure. [6] Intracellular calcium [Ca2+]i is involved in renal cellular injury [7,3] and maybe mediate the effects provoked by these drugs. This study was performed to evaluate necrosis, apoptosis, and intracellular calcium levels ([Ca2+]i) in LLC-PK1 (epithelial cell line from pig kidney) induced by GE associated with LPS and a low-osmolality media, Hexabrix (HE).

Effects of gentamicin, lipopolysaccharide, and contrast media on immortalized proximal tubular cells

Aminoglycosides are widely used in the treatment of gram-negative bacterial infections. Gentamicin (GE) acts mainly in proximal tubular cells, where it is uptake via organic anion transport system and it induces a high incidence of nephrotoxicity, which is characterized by tubular necrosis leading to acute renal failure in 10 to 50% of patients. Gram-negative bacteria have lipopolysaccharide (LPS) which is an endotoxin that causes renal damage. Moreover, many patients are undergone exams using radiologic contrast, which is a risk factor to induce a hemodynamic change in the kidney and to develop acute renal failure. Intracellular calcium [Ca2+]i is involved in renal cellular injury and maybe mediate the effects provoked by these drugs. This study was performed to evaluate necrosis, apoptosis and intracellular calcium levels ([Ca2+]i) in LLC-PK1 (epithelial cell line from pig kidney) induced by GE associated with LPS and a low-osmolality media, Hexabrix (HE).