Paclitaxel ameliorates lipopolysaccharide-induced kidney injury by binding myeloid differentiation protein-2 to block Toll-like receptor 4-mediated nuclear factor-κB activation and cytokine production.

Recent studies suggest that paclitaxel, an anticancer agent, may modulate the injury and inflammatory responses in normal tissues. However, the underlying mechanism is not fully understood. Here we have examined the effect of paclitaxel on lipopolysaccharide (LPS)-induced acute kidney injury (AKI) in mice and further studied the mechanism. At relatively low doses, paclitaxel protected against LPS-induced AKI and improved animal survival. The beneficial effects of paclitaxel were accompanied by the downregulation of tumor necrosis factor-α, interleukin-1, and interleukin-6 production. In cultured renal tubular HK-2 cells, paclitaxel decreased the DNA-binding activity of nuclear factor-κB (NF-κB) during LPS treatment, inhibited the degradation of the inhibitor of κB-α, and blocked the expression and activation of NF-κB p65. At the upstream level, paclitaxel reduced LPS-induced association of myeloid differentiation protein-2 (MD-2) with Toll-like receptor 4 (TLR4). In an in vitro assay, paclitaxel was shown to directly bind recombinant MD-2. The inhibitory effect of paclitaxel on NF-κB activation and cytokine expression disappeared in MD-2 knockdown cells, indicating that paclitaxel acts through MD-2. Collectively, these results suggest that paclitaxel may bind MD-2 to block MD-2/TLR4 association during LPS treatment, resulting in the suppression of NF-κB activation and inhibition of proinflammatory cytokine production.

Diabetes-induced renal injury in rats is attenuated by suramin.

Progression of hyperglycemia-induced renal injury is a contributing factor for diabetic nephropathy (DN)-induced end-stage renal disease (ESRD), and development of novel therapeutic strategies that act early to prevent progression of DN and ESRD are important. We examined the efficacy and mechanism(s) of suramin on hyperglycemia-induced renal injury before development of overt histological damage. Two groups of male Sprague-Dawley rats received streptozotocin (STZ) and one group received saline. Three weeks later, one STZ group received suramin (10 mg/kg). All animals were euthanized 1 week later (4 weeks). Although there was a decrease in creatinine clearance between control and STZ ± suramin rats, there was no difference in creatinine clearance between STZ rats ± suramin intervention. Liquid chromatography-tandem mass spectroscopy-based analysis revealed increases in urinary proteins that are early indicators of DN (e.g., cystatin C, clusterin, cathepsin B, retinol binding protein 4, and peroxiredoxin-1) in the STZ group, which were blocked by suramin. Endothelial intracellular adhesion molecule-1 (ICAM-1) activation, leukocyte infiltration, and inflammation; transforming growth factor-ß1 (TGF-ß1) signaling; TGF-ß1/SMAD-3-activated fibrogenic markers fibronectin-1, α-smooth muscle actin, and collagen 1A2; activation of proinflammatory and profibrotic transcription factors nuclear factor-κB (NF-κB) and signal transducer and activator of transcription factor-3 (STAT-3), respectively, were all increased in STZ rats and suramin blocked these changes. In conclusion, delayed administration of suramin attenuated 1) urinary markers of DN, 2) inflammation by blocking NF-κB activation and ICAM-1-mediated leukocyte infiltration, and 3) fibrosis by blocking STAT-3 and TGF-ß1/SMAD-3 signaling. These results support the potential use of suramin in DN.

Real-time monitoring of nuclear factor kappaB activity in cultured cells and in animal models.

Nuclear factor kappaB (NF-kappaB) is a transcription factor that plays a major role in many human disorders, including immune diseases and cancer. We designed a reporter system based on NF-kappaB responsive promoter elements driving expression of the secreted Gaussia princeps luciferase (Gluc). We show that this bioluminescent reporter is a highly sensitive tool for noninvasive monitoring of the kinetics of NF-kappaB activation and inhibition over time, both in conditioned medium of cultured cells and in the blood and urine of animals. NF-kappaB activation was successfully monitored in real time in endothelial cells in response to tumor angiogenic signaling, as well as in monocytes in response to inflammation. Further, we demonstrated dual blood monitoring of both NF-kappaB activation during tumor development as correlated to tumor formation using the NF-kappaB Gluc reporter, as well as the secreted alkaline phosphatase reporter. This NF-kappaB reporter system provides a powerful tool for monitoring NF-kappaB activity in real time in vitro and in vivo.

Intravenous administration of mannosylated cationic liposome/NFkappaB decoy complexes effectively prevent LPS-induced cytokine production in a murine liver failure model.

The purpose of this study was to inhibit endotoxin induced cytokines production and liver injury by liver non-parenchymal cell (NPC) selective delivery of nuclear factor kappaB (NFkappaB) decoy using mannosylated cationic liposomes (Man-liposomes). In this study, we examined the distribution, inhibitory effect on cytokines production and ALT/AST of intravenously injected Man-liposome/NFkappaB decoy complex. Man-liposome/[(32)P] NFkappaB decoy complexes mostly accumulated in the liver, preferentially in NPC. In a murine lipopolysaccharide-induced liver failure model, the production of tumor necrosis factor-alpha (TNFalpha), IFNgamma, IL1-beta, ALT and AST were effectively reduced by Man-liposome complexes. However, cationic or galactosylated cationic liposome complexes could not inhibit TNFalpha production.

NF-kappaB-dependent gene expression of proinflammatory cytokines in T24 cells: possible role in interstitial cystitis.

Our previous report of predominant activation of nuclear transcription factor NF-kappaB in the bladder urothelium of interstitial cystitis (IC) patients suggests a potential role for this nuclear factor in the pathogenesis of the disease. Although NF-kappaB has been implicated in the pathogenesis of several inflammatory diseases, the downstream mechanism(s) by which it can mediate its effects are still fragmentary. In this study, we examined the role of this nuclear factor on the induction of proinflammatory cytokine gene expression in human bladder carcinoma T24 cells and further examined their corresponding protein levels in the urine of IC patients. T24 cells transduced with a dominant-negative super-repressor IkappaB mutant (pAxCAmIkappaB-M) or wild-type adenoviral vectors in the presence or absence of rhTNF-alpha. Transduction efficiency and ability of pAxCAmIkappaB-M to inhibit NF-kappaB activation were monitored by in situ reporter beta-galactosidase and gel mobility shift assays, respectively. Expression profile analysis of proinflammatory cytokines was measured in cells and urine of IC patients using RT-PCR and ELISA, respectively. The activation of NF-kappaB by rhTNF-alpha was associated with 27, eight, ten and sevenfold increases in the TNF-alpha, IL-1beta, IL-6 and IL-8 transcripts, respectively. In contrast, abrogation of the TNF-alpha-induced cytokine gene expression by an adenovirus super-repressor IkappaB mutant vector demonstrate that these effects were NF-kappaB-dependent. Interestingly, the NF-kappaB-induced expression of these transcripts correlates with increased protein levels of NF-kappaB-regulated proinflammatory factors in the urine of IC patients in comparison to controls. That these factors are capable of activating NF-kappaB in urothelial cells suggests a pivotal role for this nuclear transcription factor in the pathophysiology of the disease, possibly by inducing aberrant immune and inflammatory responses within the bladder of IC patients.