Differential expression of Toll-like receptors in murine peritoneal macrophages in vitro on treatment with cisplatin

Sphingosine-1-phosphate receptor 1 activation in the central nervous system drives cisplatin-induced cognitive impairment

Cancer-related cognitive impairment (CRCI) is a major neurotoxicity affecting more than 50% of cancer survivors. The underpinning mechanisms are mostly unknown, and there are no FDA-approved interventions. Sphingolipidomic analysis of mouse prefrontal cortex and hippocampus, key sites of cognitive function, revealed that cisplatin increased levels of the potent signaling molecule sphingosine-1-phosphate (S1P) and led to cognitive impairment. At the biochemical level, S1P induced mitochondrial dysfunction, activation of NOD-, LRR-, and pyrin domain–containing protein 3 inflammasomes, and increased IL-1β formation. These events were attenuated by systemic administration of the functional S1P receptor 1 (S1PR1) antagonist FTY720, which also attenuated cognitive impairment without adversely affecting locomotor activity. Similar attenuation was observed with ozanimod, another FDA-approved functional S1PR1 antagonist. Mice with astrocyte-specific deletion of S1pr1 lost their ability to respond to FTY720, implicating involvement of astrocytic S1PR1. Remarkably, our pharmacological and genetic approaches, coupled with computational modeling studies, revealed that cisplatin increased S1P production by activating TLR4. Collectively, our results identify the molecular mechanisms engaged by the S1P/S1PR1 axis in CRCI and establish S1PR1 antagonism as an approach to target CRCI with therapeutics that have fast-track clinical application.

Salvianolic Acid C Protects against Cisplatin-Induced Acute Kidney Injury through Attenuation of Inflammation, Oxidative Stress and Apoptotic Effects and Activation of the CaMKK-AMPK-Sirt1-Associated Signaling Pathway in Mouse Models

Acute kidney injury (AKI) is a sudden reduction in kidney activity and has a high mortality rate. Salvianolic acid C (SAC), one of the main polyphenolic components of Salvia miltiorrhiza, displays significant pharmacologically active effects. An animal model of cisplatin-induced kidney injury was used to study the potential of SAC to improve AKI. First, SAC was administered intraperitoneally in mice for 10 consecutive days, and then cisplatin was administered intraperitoneally on day 7 to establish a nephrotoxicity mouse model. SAC mitigated renal histological changes, blood creatinine (CRE) and blood urea nitrogen (BUN) production and the levels of inflammatory mediators in the cisplatin-induced AKI. Furthermore, malondialdehyde (MDA) levels were reduced and glutathione (GSH) was increased after intraperitoneal injection (i.p.) administration of SAC. In addition, based on Western blot data, SAC reduced the expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) activation in mouse renal tissues. Finally, SAC diminished the level of TLR-4 expression and enhanced the production of several antioxidative enzymes (superoxidase dismutase (SOD1), glutathione peroxidase (GPx3), catalase, nuclear-factor-erythroid-2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1)), Sirtuin 1 (Sirt1), p-AMP-activated protein kinase (AMPK) and p-Ca²⁺/calmodulin-dependent protein kinase kinase (CaMKK). In addition, Sirt1 inhibition (EX 527) inverted the effect of SAC against cisplatin-induced nephrotoxicity. Collectively, SAC provides a therapeutic target with promising clinical potential after cisplatin treatment by attenuating oxidative stress and inflammation.

New Insights in the Pathogenesis of Cisplatin-Induced Nephrotoxicity

Cisplatin (cis-diamminedichloroplatinum II) is a widely used chemotherapeutic agent. However, efficacy and clinical utility of this drug is significantly limited by severe side effects such as nephrotoxicity which develops due to renal accumulation and bio-transformation in proximal tubular epithelial cells. Cisplatin-induced nephrotoxicity can be manifested as acute kidney injury (AKI), or as different types of tubulopathies, salt wasting, loss of urinary concentrating ability, and magnesium wasting. The attenuation of cisplatin-caused AKI is currently accomplished by hydration, magnesium supplementation or mannitol-induced forced diuresis. However, mannitol treatment causes over-diuresis and consequent dehydration, indicating an urgent need for the clinical use of newly designed, safe and efficacious renoprotective drug, as an additive therapy for high dose cisplatin-treated patients. Accordingly, we emphasized current knowledge regarding molecular mechanisms responsible for cisplatin-caused nephrotoxicity and we described in detail the main clinical manifestations of cisplatin-induced renal dysfunction in order to pave the way for the design of new therapeutic approaches that can minimize detrimental effects of cisplatin in the kidneys. Having in mind that most of cisplatin-induced cytotoxic effects against renal cells are, at the same time, involved in anti-tumor activity of cisplatin, new nephroprotective therapeutic strategies have to prevent renal injury and inflammation without affecting cisplatin-induced toxicity against malignant cells.

Modulatory effect of zingerone against cisplatin or γ-irradiation induced hepatotoxicity by molecular targeting regulation

Zingerone (ZO) is an ingredient of ginger (Zingiber officinale) which has different pharmacological properties. The objective of this research was to evaluate the protective effect of ZO against Cisplatin (Cis) or γ-Irradiation (IR)-induced hepatotoxicity in rats. ZO was given orally for consecutive 14 days prior to the treatment with Cis or exposure to IR at 15th day. Animals were sacrificed at the 23rd day. Cis or IR induced a marked increase in MAPK signal transduction as evidenced by increased p38 MAPK, JNK and ErK1/2. CYP2E1 and NADPH oxidase were significantly up-regulated. Inflammatory markers (TLR4, iNOS, COX-2 and MPO) and liver enzymes (AST, ALT and ALP) activities were also increased. Administration of ZO significantly ameliorated the above mentioned parameters.

Molecular mechanisms of cisplatin-induced nephrotoxicity: a balance on the knife edge between renoprotection and tumor toxicity

Background

Cisplatin (cis-diamminedichloroplatinum II, CDDP) is one of the most effective chemotherapeutic agents. However, its clinical use is limited due to the severe side effects, including nephrotoxicity and acute kidney injury (AKI) which develop due to renal accumulation and biotransformation of CDDP. The alleviation or prevention of CDDP-caused nephrotoxicity is currently accomplished by hydration, magnesium supplementation or mannitol-induced forced diuresis which is considered for high-dose CDDP-treated patients. However, mannitol treatment causes over-diuresis and consequent dehydration in CDDP-treated patients, indicating an urgent need for the clinical use of safe and efficacious renoprotective drug as an additive therapy for high dose CDDP-treated patients.

Main body

In this review article we describe in detail signaling pathways involved in CDDP-induced apoptosis of renal tubular cells, oxidative stress and inflammatory response in injured kidneys in order to pave the way for the design of new therapeutic approaches that can minimize CDDP-induced nephrotoxicity. Most of these molecular pathways are, at the same time, crucially involved in cytotoxic activity of CDDP against tumor cells and potential alterations in their function might mitigate CDDP-induced anti-tumor effects.

Conclusion

Despite the fact that many molecules were designated as potential therapeutic targets for renoprotection against CDDP, modulation of CDDP-induced nephrotoxicity still represents a balance on the knife edge between renoprotection and tumor toxicity.

P-MAPA immunotherapy potentiates the effect of cisplatin on serous ovarian carcinoma through targeting TLR4 signaling

Background

Toll-like receptors (TLRs) are transmembrane proteins expressed on the surface of ovarian cancer (OC) and immune cells. Identifying the specific roles of the TLR-mediated signaling pathways in OC cells is important to guide new treatments. Because immunotherapies have emerged as the adjuvant treatment for patients with OC, we investigated the effect of a promising immunotherapeutic strategy based on protein aggregate magnesium-ammonium phospholinoleate-palmitoleate anhydride (P-MAPA) combined with cisplatin (CIS) on the TLR2 and TLR4 signaling pathways via myeloid differentiation factor 88 (MyD88) and TLR-associated activator of interferon (TRIF) in an in vivo model of OC.

Methods

Tumors were chemically induced by a single injection of 100 μg of 7,12-dimethylbenz(a)anthracene (DMBA) directly under the left ovarian bursa in Fischer 344 rats. After the rats developed serous papillary OC, they were given P-MAPA, CIS or the combination P-MAPA+CIS as therapies. To understand the effects of the treatments, we assessed the tumor size, histopathology, and the TLR2- and TLR4-mediated inflammatory responses.

Results

Although CIS therapy was more effective than P-MAPA in reducing the tumor size, P-MAPA immunotherapy significantly increased the expressions of TLR2 and TLR4. More importantly, the combination of P-MAPA with CIS showed a greater survival rate compared to CIS alone, and exhibited a significant reduction in tumor volume compared to P-MAPA alone. The combination therapy also promoted the increase in the levels of the following OC-related proteins: TLR4, MyD88, TRIF, inhibitor of phosphorylated NF-kB alpha (p-IkBα), and nuclear factor kappa B (NF-kB p65) in both cytoplasmic and nuclear sites. While P-MAPA had no apparent effect on tumor necrosis factor alpha (TNF-α) and interleukin (IL)-6, it seems to increase interferon-γ (IFN-γ), which may induce the Thelper (Th1)-mediated immune response.

Conclusion

Collectively, our results suggest that P-MAPA immunotherapy combined with cisplatin could be considered an important therapeutic strategy against OC cells based on signaling pathways activated by TLR4.

Involvement of reactive oxygen species in ionizing radiation-induced upregulation of cell surface Toll-like receptor 2 and 4 expression in human monocytic cells

Toll-like receptors (TLRs) are pattern recognition receptors that recognize pathogen-associated molecular patterns and are indispensable for antibacterial and antiviral immunity. Our previous report showed that ionizing radiation increases the cell surface expressions of TLR2 and TLR4 and enhances their responses to agonists in human monocytic THP1 cells. The present study investigated how ionizing radiation increases the cell surface expressions of TLR2 and TLR4 in THP1 cells. The THP1 cells treated or not treated with pharmaceutical agents such as cycloheximide and N-acetyl-L-cysteine (NAC) were exposed to X-ray irradiation, following which the expressions of TLRs and mitogen-activated protein kinase were analyzed. X-ray irradiation increased the mRNA expressions of TLR2 and TLR4, and treatment with a protein synthesis inhibitor cycloheximide abolished the radiation-induced upregulation of their cell surface expressions. These results indicate that radiation increased those receptors through de novo protein synthesis. Furthermore, treatment with an antioxidant NAC suppressed not only the radiation-induced upregulation of cell surface expressions of TLR2 and TLR4, but also the radiation-induced activation of the c-Jun N-terminal kinase (JNK) pathway. Since it has been shown that the inhibitor for JNK can suppress the radiation-induced upregulation of TLR expression, the present results suggest that ionizing radiation increased the cell surface expressions of TLR2 and TLR4 through reactive oxygen species-mediated JNK activation.

Puerarin attenuates cisplatin-induced rat nephrotoxicity: The involvement of TLR4/NF-κB signaling pathway

Puerarin was a major isoflavonoid derived from the Chinese medical herb radix puerariae (Gegen). In present study effect of puerarin on cisplatin nephrotoxicity was evaluated. Rat model of nephrotoxicity was established by a single intraperitoneal injection of cisplatin (7mg/kg). Puerarin was administrated through caudal vein injection once per day at the dose of 10mg/kg, 30mg/kg and 50mg/kg. Biochemical assays showed that after cisplatin treatment the serum urea and creatinine increased significantly compared with control (P<0.05). Cisplatin treatment significantly increased xanthine oxidase (XO) activity and malondialdehyde (MDA) formation, and significantly decreased the levels and /or activities of enzymatic and non-enzymatic antioxidants (GSH, GPx, GST, GR, SOD, CAT), in the kidney tissues. Renal levels of TNF-α and IL-6, two important inflammatory cytokines, were also upregulated by cisplatin. Histopathological examination indicated that cisplatin treatment resulted in severe necrosis and degeneration, hyaline casts in the tubules, intertubular hemorrhage, congestion and swelling in glomerulus and leukocytes infiltration in the kidney tissues. Western blot results demonstrated that cisplatin increased TLR4 and NF-κB protein expression in the kidney tissues. However, all these changes induced by cisplatin were significantly attenuated by puerarin treatment in dose-dependent manner, which indicated the renal protective effect of puerarin. Cell culture experiments illustrated that puerarin alone treatment concentration-dependently inhibited COLO205 and HeLa tumor cell growth and dose-dependently promoted the antitumor activity of cisplatin in COLO205 and HeLa tumor cells. The promotion effects might be attributed to suppression of cisplatin-increased NF-κB p65 expression by puerarin. Taken together, findings in this study suggested that puerarin exhibited renal protection against cisplatin nephrotoxicity via inhibiting TLR4/NF-κB signaling, with no inhibition but promotion effect on the antitumor activity of cisplatin. Puerarin might be a promising adjuvant agent for cisplatin chemotherapy.

Macrophages in kidney injury, inflammation, and fibrosis

Macrophages are found in normal kidney and in increased numbers in diseased kidney, where they act as key players in renal injury, inflammation, and fibrosis. Macrophages are highly heterogeneous cells and exhibit distinct phenotypic and functional characteristics in response to various stimuli in the local microenvironment in different types of kidney disease. In kidney tissue necrosis and/or infection, damage- and/or pathogen-associated molecular patterns induce pro-inflammatory macrophages, which contribute to further tissue injury, inflammation, and subsequent fibrosis. Apoptotic cells and anti-inflammatory factors in post-inflammatory tissues induced anti-inflammatory macrophages, which can mediate kidney repair and regeneration. This review summarizes the role of macrophages with different phenotypes in kidney injury, inflammation, and fibrosis in various acute and chronic kidney diseases. Understanding alterations of kidney microenvironment and the factors that control the phenotype and functions of macrophages may offer an avenue for the development of new cellular and cytokine/growth factor-based therapies as alternative treatment options for patients with kidney disease.

Characterization of Toll-like receptor-4 (TLR-4) in the spleen and thymus of Swiss albino mice and its modulation in experimental endotoxemia

Expression of innate immune receptors varies among organs and species and within different strains among the same species; thus, periodic classification of different pattern recognition receptors in the available strains is necessary to initiate different therapeutic approaches to combat inflammation. On characterization of TLR-4 in spleen and thymus of Swiss albino mice—with no reports of TLR-4 expression—induced with endotoxemia, it was found that the mode of expression varied among the organs at both mRNA and protein level in a time-dependent manner. Their functionality was verified by measuring proinflammatory and anti-inflammatory cytokines. In the in vitro study using isolated macrophages and lymphocytes from the same organs, the expression of TLR-4 after a shorter period of LPS stimulation was verified. The results substantiated the potent role of macrophage on LPS challenge compared to lymphocytes. The diverse pattern of TLR-4 expression on different cell population indicated their distinct functional activity in LPS-endotoxemia. It may be hypothesized that the expression patterns of TLR-4 could be different based on the anatomical localization and the varying bacterial milieu or bacterial endotoxin encountered in each anatomical location. Thus, blocking TLR-4 or administering IL-6 or IL-10 might impart protection against endotoxemia in the clinical field.

Pathogenic and protective role of macrophages in kidney disease

Macrophages (MΦ) are located throughout kidney tissue, where they play important roles in homeostasis, surveillance, tolerance, and cytoprotection. MΦ are highly heterogeneous cells and exhibit distinct phenotypic and functional characteristics depending on their microenvironment and the disease type and stage. Recent studies have identified a dual role for MΦ in several murine models of kidney disease. In this review, we discuss the pathogenic and protective roles of the various MΦ subsets in experimental and human kidney diseases and summarize current progress toward the therapeutic use of MΦ in kidney diseases.

Activation of lipopolysaccharide-TLR4 signaling accelerates the ototoxic potential of cisplatin in mice

Dysfunction in immune surveillance during anticancer chemotherapy of patients often causes weakness of the host defense system and a subsequent increase in microbial infections. However, the deterioration of organ-specific function related to microbial challenges in cisplatin-treated patients has not yet been elucidated. In this study, we investigated cisplatin-induced TLR4 expression and its binding to LPS in mouse cochlear tissues and the effect of this interaction on hearing function. Cisplatin increased the transcriptional and translational expression of TLR4 in the cochlear tissues, organ of Corti explants, and HEI-OC1 cells. Furthermore, cisplatin increased the interaction between TLR4 and its microbial ligand LPS, thereby upregulating the production of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6, via NF-κB activation. In C57BL/6 mice, the combined injection of cisplatin and LPS caused severe hearing impairment compared with that in the control, cisplatin-alone, or LPS-alone groups, whereas this hearing dysfunction was completely suppressed in both TLR4 mutant and knockout mice. These results suggest that hearing function can be easily damaged by increased TLR expression and microbial infections due to the weakened host defense systems of cancer patients receiving therapy comprising three to six cycles of cisplatin alone or cisplatin combined with other chemotherapeutic agents. Moreover, such damage can occur even though patients may not experience ototoxic levels of cumulative cisplatin concentration.

Mechanisms of Cisplatin nephrotoxicity

Cisplatin is a widely used and highly effective cancer chemotherapeutic agent. One of the limiting side effects of cisplatin use is nephrotoxicity. Research over the past 10 years has uncovered many of the cellular mechanisms which underlie cisplatin-induced renal cell death. It has also become apparent that inflammation provoked by injury to renal epithelial cells serves to amplify kidney injury and dysfunction in vivo. This review summarizes recent advances in our understanding of cisplatin nephrotoxicity and discusses how these advances might lead to more effective prevention.

TLR4-mediated activation of mouse macrophages by Korean mistletoe lectin-C (KML-C)

Korean mistletoe lectin (KML-C) is an adjuvant that activates systemic and mucosal immune cells to release cytokines including TNF-alpha, which induces immunity against viruses and cancer cells. Although the immunomodulatory activity of KML-C has been well established, the underlying mechanism of action of KML-C has yet to be explored. When mouse peritoneal macrophages were treated with KML-C, both transcription and translation of TLR4 were upregulated. KML-C-induced TLR4 downstream events were similar to those activated by LPS: the upregulation of interleukin-1 receptor-associated kinase-1 (IRAK1); resulting in macrophage activation and TNF-alpha production. When TLR4 was blocked using a TLR4-specific neutralizing antibody, TNF-alpha production from the macrophages was significantly inhibited. Moreover, TLR4-deficient mouse macrophages treated with KML-C also secreted greatly reduced level of TNF-alpha secretion. Finally, TLR4 molecules were co-precipitated with KML-C, to which agarose beads were conjugated, indicating that those molecules are associated. These data indicate that KML-C activates mouse macrophages to secrete TNF-alpha by interacting with the TLR4 molecule and activating its signaling pathways.