Doxycycline attenuates cisplatin-induced acute kidney injury through pleiotropic effects

The serine protease plasmin plays detrimental roles in epithelial sodium channel activation and podocyte injury in Dahl salt-sensitive rats

Salt-sensitive hypertension is associated with poor clinical outcomes. The epithelial sodium channel (ENaC) in the kidney plays pivotal roles in sodium reabsorption and blood pressure regulation, in which its γ subunit is activated by extracellular serine proteases. In proteinuric nephropathies, plasmin filtered through injured glomeruli reportedly activates γENaC in the distal nephron and causes podocyte injury. We previously reported that Dahl salt-sensitive (DS) rats fed a high-salt (HS) diet developed hypertension and proteinuria along with γENaC activation and that a synthetic serine protease inhibitor, camostat mesilate, mitigated these changes. However, the role of plasmin in DS rats remained unclear. In this study, we evaluated the relationship between plasmin and hypertension as well as podocyte injury and the effects of plasmin inhibitors in DS rats. Five-week-old DS rats were divided into normal-salt diet, HS diet, and HS+plasmin inhibitor (either tranexamic acid [TA] or synthetic plasmin inhibitor YO-2) groups. After blood pressure measurement and 24 h urine collection over 5 weeks, rats were sacrificed for biochemical analyses. The HS group displayed severe hypertension and proteinuria together with activation of plasmin in urine and γENaC in the kidney, which was significantly attenuated by YO-2 but not TA. YO-2 inhibited the attachment of plasmin(ogen) to podocytes and alleviated podocyte injury by inhibiting apoptosis and inflammatory/profibrotic cytokines. YO-2 also suppressed upregulation of protease-activated receptor-1 and phosphorylated ERK1/2. These results indicate an important role of plasmin in the development of salt-sensitive hypertension and related podocyte injury, suggesting plasmin inhibition as a potential therapeutic strategy.

Doxycycline Attenuates Doxorubicin-Induced Cardiotoxicity by Improving Myocardial Energy Metabolism in Rats

Aim: Evaluate the influence of doxycycline, an anti-inflammatory and matrix metalloproteinase (MMP) inhibitor, on the attenuation of chronic doxorubicin-induced cardiotoxicity in rats. Methods: We allocated male Wistar rats into four groups: control (C), doxorubicin (D), doxycycline (inhibitor of MMP, IM), and Dox + doxycycline (DIM). Groups IM and DIM received doxycycline (5 mg/kg, IP) once a week for 4 weeks. In addition, 48 h after every doxycycline injection, groups D and DIM received Dox (5 mg/kg, IP). We performed echocardiogram and evaluated TIMP-4 and collagen I protein expression, MMP-2 activity, and oxidative stress and myocardial metabolism. Results: Doxorubicin promotes left atrium (LA) and left ventricle (LV) dilatation and decreases in LV fractional shortening, which was improved by doxycycline. Moreover, doxycycline attenuated the LV cardiomyocyte hypertrophy and collagen type I expression. Doxorubicin increased phosphofructokinase and decreased beta-hydroxyacyl Co-A dehydrogenase, pyruvate dehydrogenase, citrate synthase, and ATP synthase activity, which was partially attenuated by doxycycline. Lastly, doxycycline improved antioxidant enzyme activity in the DIM group. Conclusion: Doxorubicin increases oxidative stress and promotes changes in myocardial energy metabolism, accompanied by structural and functional changes. Doxycycline attenuated the doxorubicin-induced cardiotoxicity, at least in part, through changes in myocardial energy metabolism.

A Chinese Medicine Compound Alleviates Cisplatin-Induced Acute Kidney Injury via Its Antiapoptosis and Anti-Inflammation Effects in Mice

Cisplatin, also known as cis-diamine dichloroplatinum (CDDP), is a widely used chemotherapeutic drug. However, its application is limited by the occurrence of serious nephrotoxicity. Currently, no effective therapy is available for combating CDDP-induced acute kidney injury (AKI). In the present study, we investigated the efficacy of Jianpi Yishen Tang (JPYST), a traditional Chinese medicine (TCM) compound commonly used to treat chronic kidney disease, against CDDP-induced AKI. In the CDDP + JPYST group, male mice were pretreated with JPYST (18.35 g/kg/day) for 5 consecutive days before receiving a single dose of CDDP (20 mg/kg), all mice were sacrificed 72 h after the CDDP injection. Results showed that JPYST suppressed CDDP-induced kidney dysfunction and tubular damage scores in the mice. Mechanistically, JPYST treatment attenuated CDDP-induced renal tubular cell apoptosis in AKI mice, as manifested by a marked decreased in TUNEL-positive cell counts, downregulation of the pro-apoptotic proteins Bax, Bad and caspase 3, and upregulation of the antiapoptotic protein Bcl-2 in kidney tissues. Meanwhile, JPYST decreased the expression of inflammatory cytokines TNF-α, IL-1β, and IL-6 in the serum and renal tissues of mice following CDDP administration. These factors are involved in suppressing the activation of phospho-NF-κB p65 in tubular epithelial cells. Taken together, these findings demonstrated that JPYST exerts renoprotective effects against CDDP-induced AKI through antiapoptosis and anti-inflammation effects, and these are associated with downregulation of NF-κB activation. Therefore, JPYST has potential for development of treatment therapies against CDDP-induced AKI.

Renoprotective Effect of Vardenafil and Avanafil in Contrast-Induced Nephropathy: Emerging Evidence from an Animal Model

The potential renoprotective effects of vardenafil (VAR) have been evaluated in a very limited number of studies using acute kidney injury animal models other than contrast-induced nephropathy (CIN) with promising results, while avanafil (AVA) has not been evaluated in this respect before. The purpose of this study was to evaluate for the first time the potential renoprotective effect of VAR and AVA in a rat model of CIN. Twenty-five male Wistar rats were equally assigned into five groups: control, CIN, CIN+N-acetyl cysteine (NAC) (100 mg/kg/day) as a positive control, CIN+VAR (10 mg/kg/day) and CIN+AVA (50 mg/kg/day). CIN was induced by dehydration, inhibition of prostaglandin and nitric oxide synthesis as well as exposure to the contrast medium (CM). Serum Cr (sCr) levels were measured at 24 and 48 h after CIN induction. At 48 h of CM exposure, animals were sacrificed. Matrix metalloproteinase (MMP) 2 (MMP-2) and MMP-9, kidney injury molecule 1 (KIM-1) and cystatin-C (Cys-C) were measured on renal tissue. Histopathological findings were evaluated on kidney tissue. All treatment groups had close to normal kidney appearance. sCr levels subsided in all treatment groups compared to CIN group at 48 h following CIN induction. A significant decline in the levels of MMP-2, MMP-9, KIM-1 and Cys-C compared to CIN group was observed. These results provide emerging evidence that VAR and AVA may have the potential to prevent CIN.

Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in kidney disease

Matrix metalloproteinases (MMPs) are a group of zinc and calcium endopeptidases which cleave extracellular matrix (ECM) proteins. They are also involved in the degradation of cell surface components and regulate multiple cellular processes, cell to cell interactions, cell proliferation, and cell signaling pathways. MMPs function in close interaction with the endogenous tissue inhibitors of matrix metalloproteinases (TIMPs), both of which regulate cell turnover, modulate various growth factors, and participate in the progression of tissue fibrosis and apoptosis. The multiple roles of MMPs and TIMPs are continuously elucidated in kidney development and repair, as well as in a number of kidney diseases. This chapter focuses on the current findings of the significance of MMPs and TIMPs in a wide range of kidney diseases, whether they result from kidney tissue changes, hemodynamic alterations, tubular epithelial cell apoptosis, inflammation, or fibrosis. In addition, the potential use of these endopeptidases as biomarkers of renal dysfunction and as targets for therapeutic interventions to attenuate kidney disease are also explored in this review.

Nonantibiotic Properties of Tetracyclines in Rosacea and Their Clinical Implications

Rosacea is one of the most common inflammatory skin diseases in the United States, with a complex pathophysiology. One of the major components of the pathophysiology of rosacea is an abnormal immune detection and response to stimuli. Tetracyclines and their derivatives, including minocycline and doxycycline, have anti-inflammatory properties independent of their antibacterial activity that correlate with certain aspects of the pathophysiology, and these drugs are often used by dermatologists to treat rosacea. Biological actions of tetracyclines correlating with rosacea include anti-inflammatory and antioxidative activities, inhibitory effects on angiogenesis, and proteolysis. The objective of this review is to re-establish the current understanding of tetracyclines and their mechanism of action as they relate to the pathophysiology and treatment of rosacea for clinicians. This includes reviewing the inflammatory aspects of rosacea that correlate with the known nonantibiotic properties of tetracyclines and providing the most up-to-date clinical evidence supporting the use of tetracyclines to treat rosacea. Given the evolving and multifactorial nature of pathophysiology, this review offers clinicians a unified picture that includes research on the links between rosacea pathophysiology and clinical presentation, the nonantibiotic properties of tetracyclines that relate to pathophysiologic pathways in rosacea, and the potential for clinical application of tetracyclines in rosacea therapy.

Key metalloproteinase-mediated pathways in the kidney

Matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinases (ADAMs) belong to the metzincin family of zinc-containing multidomain molecules, and can act as soluble or membrane-bound proteases. These enzymes inactivate or activate other soluble or membrane-expressed mediator molecules, which enables them to control developmental processes, tissue remodelling, inflammatory responses and proliferative signalling pathways. The dysregulation of MMPs and ADAMs has long been recognized in acute kidney injury and in chronic kidney disease, and genetic targeting of selected MMPs and ADAMs in different mouse models of kidney disease showed that they can have detrimental and protective roles. In particular, MMP-2, MMP-7, MMP-9, ADAM10 and ADAM17 have been shown to have a mainly profibrotic effect and might therefore represent therapeutic targets. Each of these proteases has been associated with a different profibrotic pathway that involves tissue remodelling, Wnt-β-catenin signalling, stem cell factor-c-kit signalling, IL-6 trans-signalling or epidermal growth factor receptor (EGFR) signalling. Broad-spectrum metalloproteinase inhibitors have been used to treat fibrotic kidney diseases experimentally but more targeted approaches have since been developed, including inhibitory antibodies, to avoid the toxic side effects initially observed with broad-spectrum inhibitors. These advances not only provide a solid foundation for additional preclinical studies but also encourage further translation into clinical research.

Doxycycline Induces Apoptosis of Brucella Suis S2 Strain-Infected HMC3 Microglial Cells by Activating Calreticulin-Dependent JNK/p53 Signaling Pathway

Neurobrucellosis is a chronic complication of human brucellosis that is caused by the presence of Brucella spp in the central nervous system (CNS) and the inflammation play a key role on the pathogenesis. Doxycycline (Dox) is a widely used antibiotic that induces apoptosis of bacteria-infected cells. However, the mechanisms of Brucella inhibition of microglial apoptosis and Dox induction of apoptosis are still poorly understood. In this study, we found that Brucella suis S2 strain (B. suis S2) increased calreticulin (CALR) protein levels and inhbited HMC3 cell apoptosis. Hence, we constructed two HMC3 cell line variants, one with stable overexpression (HMC3-CALR) and one with low expression of CALR (HMC3-sh-CALR). CALR was found to decrease levels of p-JNK and p-p53 proteins, as well as suppress apoptosis in HMC3 cells. These findings suggest that CALR suppresses apoptosis by inhibiting the JNK/p53 signaling pathway. Next, we treated HMC3, HMC3-CALR and HMC3-sh-CALR cell lines with B. suis S2 or Dox. Our results demonstrate that B. suis S2 restrains the JNK/p53 signaling pathway to inhibit HMC3 cell apoptosis via increasing CALR protein expression, while Dox plays the opposite role. Finally, we treated B. suis S2-infected HMC3 cells with Dox. Our results confirm that Dox induces JNK/p53-dependent apoptosis in B. suis S2-infected HMC3 cells through inhibition of CALR protein expression. Taken together, these results reveal that CALR and the JNK/p53 signaling pathway may serve as novel therapeutic targets for treatment of neurobrucellosis.

Effect of chemically modified tetracycline-8 (CMT-8) on hematology, blood chemistry, cytokines and peripheral blood lymphocyte subsets of healthy dogs

Tetracyclines are antibiotics widely used in human and veterinary medicine. Effects on the immune system and inflammatory response, including effects on blood leukocytes proliferation and function and in cytokines synthesis, have been described. Chemically modified tetracyclines (CMT) have lost their antimicrobial activity, but maintain these other properties. This study analyzes the effect of chemically modified tetracycline-8 (CMT-8) on the evolution of complete blood count, blood chemistry, the mRNA expression of selected cytokines and peripheral blood lymphocyte subpopulations distribution in healthy dogs. CMT-8 at a dose of 10 mg/kg once daily was administered per os to six healthy dogs. A control group of five healthy dogs, living in the same conditions than dogs treated with CMT-8, received placebo with an identical therapeutic regimen. When given at the doses used in this study, no side effects of CMT-8 were detected, suggesting a good tolerance and a limited toxicity of the drug. Dogs treated with CMT-8 showed a gradual increase in mean corpuscular hemoglobin. The administration of CMT-8 in healthy dogs did not affect blood mRNA expression of IFN-γ, TNFα, IL-4, IL-6, IL-10, IL-12 p40 and IL-13. However, the lymphocytes expressing class II MHC on their surface decreased during the first two weeks of CMT-8 treatment and subsequently increased for the next three months. Considering the absence of antimicrobial properties of the drug, the effects of CMT-8 detected in this study seem to be unrelated to the classical antimicrobial activity attributed to tetracyclines.

A meta-analysis of preclinical studies using antioxidants for the prevention of cisplatin nephrotoxicity: implications for clinical application

Cisplatin is an effective chemotherapeutic drug whose clinical use and efficacy are limited by its nephrotoxicity, which affects mainly the renal tubules and vasculature. It accumulates in proximal and distal epithelial tubule cells and causes oxidative stress-mediated cell death and malfunction. Consequently, many antioxidants have been tested for their capacity to prevent cisplatin nephrotoxicity. In this study, we made a systematic review of the literature and meta-analyzed 152 articles, which tested the nephroprotective effect of isolated compounds or mixtures of natural origin on cisplatin nephrotoxicity in preclinical models. This meta-analysis identified the most effective candidates and examined the efficacy obtained by antioxidants administered by the oral and intraperitoneal routes. By comparing with a recent, similar meta-analysis performed on clinical studies, this article identifies a disconnection between preclinical and clinical research, and contextualizes, discusses, and integrates the existing preclinical information toward the optimized selection of candidates to be further explored (clinical level). Despite proved efficacy, this article discusses the barriers limiting the clinical development of natural mixtures, such as those in extracts from Calendula officinalis flowers and Heliotropium eichwaldii roots. On the contrary, isolated compounds are more straightforward candidates, among which arjunolic acid and quercetin stand out in this meta-analysis.

The Yin and Yang of Alarmins in Regulation of Acute Kidney Injury

Acute kidney injury (AKI) is a major clinical burden affecting 20 to 50% of hospitalized and intensive care patients. Irrespective of the initiating factors, the immune system plays a major role in amplifying the disease pathogenesis with certain immune cells contributing to renal damage, whereas others offer protection and facilitate recovery. Alarmins are small molecules and proteins that include granulysins, high-mobility group box 1 protein, interleukin (IL)-1α, IL-16, IL-33, heat shock proteins, the Ca++ binding S100 proteins, adenosine triphosphate, and uric acid. Alarmins are mostly intracellular molecules, and their release to the extracellular milieu signals cellular stress or damage, generally leading to the recruitment of the cells of the immune system. Early studies indicated a pro-inflammatory role for the alarmins by contributing to immune-system dysregulation and worsening of AKI. However, recent developments demonstrate anti-inflammatory mechanisms of certain alarmins or alarmin-sensing receptors, which may participate in the prevention, resolution, and repair of AKI. This dual function of alarmins is intriguing and has confounded the role of alarmins in AKI. In this study, we review the contribution of various alarmins to the pathogenesis of AKI in experimental and clinical studies. We also analyze the approaches for the therapeutic utilization of alarmins for AKI.

The Predictive Role of the Biomarker Kidney Molecule-1 (KIM-1) in Acute Kidney Injury (AKI) Cisplatin-Induced Nephrotoxicity

Acute kidney injury (AKI) following platinum-based chemotherapeutics is a frequently reported serious side-effect. However, there are no approved biomarkers that can properly identify proximal tubular injury while routine assessments such as serum creatinine lack sensitivity. Kidney-injury-molecule 1 (KIM-1) is showing promise in identifying cisplatin-induced renal injury both in vitro and in vivo studies. In this review, we focus on describing the mechanisms of renal tubular cells cisplatin-induced apoptosis, the associated inflammatory response and oxidative stress and the role of KIM-1 as a possible biomarker used to predict cisplatin associated AKI.

Recent Advances in Models, Mechanisms, Biomarkers, and Interventions in Cisplatin-Induced Acute Kidney Injury

Cisplatin is a widely used chemotherapeutic agent used to treat solid tumours, such as ovarian, head and neck, and testicular germ cell. A known complication of cisplatin administration is acute kidney injury (AKI). The development of effective tumour interventions with reduced nephrotoxicity relies heavily on understanding the molecular pathophysiology of cisplatin-induced AKI. Rodent models have provided mechanistic insight into the pathophysiology of cisplatin-induced AKI. In the subsequent review, we provide a detailed discussion of recent advances in the cisplatin-induced AKI phenotype, principal mechanistic findings of injury and therapy, and pre-clinical use of AKI rodent models. Cisplatin-induced AKI murine models faithfully develop gross manifestations of clinical AKI such as decreased kidney function, increased expression of tubular injury biomarkers, and tubular injury evident by histology. Pathways involved in AKI include apoptosis, necrosis, inflammation, and increased oxidative stress, ultimately providing a translational platform for testing the therapeutic efficacy of potential interventions. This review provides a discussion of the foundation laid by cisplatin-induced AKI rodent models for our current understanding of AKI molecular pathophysiology.