Relaxin protects against renal ischemia-reperfusion injury

Phoenixin-14 may ameliorate testicular damage caused by torsion-detorsion by reducing oxidative stress and inflammation in prepubertal rats

The present study aimed to investigate the effects of Phoenixin-14 (PNX-14) on oxidative damage, inflammatory response, histopathological variations, and serum testosterone levels in testicular tissues. Forty-eight Wistar albino prepubertal male rats were divided into 4 groups (Sham, TTD, TT+PNX+TD, TTD+PNX) (n=12). The torsion period was 2 hours and the detorsion period was 24 hours in the testicular torsion/detorsion (TD) groups. A single PNX-14 (50 µg/kg) dose was injected into the rats in the TT+PNX TD group on the 90th minute of torsion, and it was injected into the rats in the TTD+PNX group at the beginning of detorsion. Oxidative damage in testicular tissues was determined based on superoxide dismutase (SOD), malondialdehyde (MDA), total antioxidant status (TAS) and total oxidant status (TOS), and inflammatory damage was determined based on TNF-α and IL-6 levels. Histopathological variations were investigated with the Periodic Acid Schiff (PAS) staining method in testicular tissues and analyzed based on Johnsen scores. Spermatogonia cells were examined immunohistochemically. Serum testosterone levels were determined with the enzyme-linked immunosorbent assay (ELISA). A significant increase in oxidative stress and inflammation parameters was determined in the TTD group when compared to the other groups (p<0.05). PNX-14 treatment led to a statistically significant decrease in these parameters and significantly repaired the TD damage in testicular tissue (p<0.05). Johnsen scoring revealed significant improvement in PNX-14 groups and an increase in spermatogonia count, supporting the biochemical findings (p<0.05). PNX-14 could be a potential therapeutic agent in testicular TD damage and further studies should be conducted to elucidate the present study findings.

Relaxin in fibrotic ligament diseases: Its regulatory role and mechanism

Fibrotic ligament diseases (FLDs) are diseases caused by the pathological accumulation of periarticular fibrotic tissue, leading to functional disability around joint and poor life quality. Relaxin (RLX) has been reported to be involved in the development of fibrotic lung and liver diseases. Previous studies have shown that RLX can block pro-fibrotic process by reducing the excess extracellular matrix (ECM) formation and accelerating collagen degradation in vitro and in vivo. Recent studies have shown that RLX can attenuate connective tissue fibrosis by suppressing TGF-β/Smads signaling pathways to inhibit the activation of myofibroblasts. However, the specific roles and mechanisms of RLX in FLDs remain unclear. Therefore, in this review, we confirmed the protective effect of RLX in FLDs and summarized its mechanism including cells, key cytokines and signaling pathways involved. In this article, we outline the potential therapeutic role of RLX and look forward to the application of RLX in the clinical translation of FLDs.

Experimental Static Cold Storage of the Rat Uterus: Protective Effects of Relaxin- or Erythropoietin-Supplemented HTK-N Solutions

Uterus transplantation (UTx) is the only treatment method for women with absolute uterine infertility. Currently, the number of grafts retrieved from deceased donors is increasing; hence, prolonged cold ischemia time is inevitable. Thus, this study was designed to assess the effect of the novel relaxin (RLN)- or erythropoietin (EPO)-supplemented Custodiol-N (HTK-N) solutions in an experimental uterus static cold storage (SCS) model. A total of 15 Sprague Dawley rats were used. Uterus horns were randomly assigned into three groups (n = 10/group). SCS was performed by keeping samples at 4 °C in HTK-N solution without or with different additives: 10 IU/mL EPO or 20 nM RLN. Tissue samples were taken after 8 and 24 h of preservation. Uterine tissue histology, and biochemical and immunohistochemical markers were analyzed. No significant differences in SCS-induced tissue damage were observed between groups after 8 h of preservation. Uterine tissue histology, MDA, SOD levels and the TUNEL-positive cell number showed severe damage in HTK-N without additives after 24 h of preservation. This damage was significantly attenuated by adding RLN to the preservation solution. EPO showed no favorable effect. Our study shows that RLN as an additive to an HTK-N solution can serve as an effective uterine tissue preservative in the uterus SCS setting.

Innovative immunosuppression in kidney transplantation: A challenge for unmet needs

Due to the optimal results obtained in kidney transplantation and to the lack of interest of the industries, new innovative drugs in kidney transplantation are difficult to be encountered. The best strategy to find the new drugs recently developed or under development is to search in the sections of kidney transplantation still not completely covered by the drugs on the market. These unmet needs are the prevention of delayed graft function (DGF), the protection of the graft over the long time and the desensitization of preformed anti human leukocyte antigen antibodies and the treatment of the acute antibody-mediated rejection. These needs are particularly relevant due to the expansion of some kind of kidney transplantation as transplantation from non-heart beating donor and in the case of antibody-incompatible grafts. The first are particularly exposed to DGF, the latter need a safe desensitization and a safe treatments of the antibody mediated rejections that often occur. Particular caution is needed in treating these drugs. First, they are described in very recent studies and the follow-up of their effect is of course rather short. Second, some of these drugs are still in an early phase of study, even if in well-conducted randomized controlled trials. Particular caution and a careful check need to be used in trials launched 2 or 3 years ago. Indeed, is always necessary to verify whether the study is still going on or whether and why the study itself was abandoned.

Relaxin as an anti-fibrotic treatment: Perspectives, challenges and future directions

Fibrosis refers to the scarring and hardening of tissues, which results from a failed immune system-coordinated wound healing response to chronic organ injury and which manifests from the aberrant accumulation of various extracellular matrix components (ECM), primarily collagen. Despite being a hallmark of prolonged tissue damage and related dysfunction, and commonly associated with high morbidity and mortality, there are currently no effective cures for its regression. An emerging therapy that meets several criteria of an effective anti-fibrotic treatment, is the recombinant drug-based form of the human hormone, relaxin (also referred to as serelaxin, which is bioactive in several other species). This review outlines the broad anti-fibrotic and related organ-protective roles of relaxin, mainly from studies conducted in preclinical models of ageing and fibrotic disease, including its ability to ameliorate several aspects of fibrosis progression and maturation, from immune cell infiltration, pro-inflammatory and pro-fibrotic cytokine secretion, oxidative stress, organ hypertrophy, cell apoptosis, myofibroblast differentiation and ECM production, to its ability to facilitate established ECM degradation. Studies that have compared and/or combined these therapeutic effects of relaxin with current standard of care medication have also been discussed, along with the main challenges that have hindered the translation of the anti-fibrotic efficacy of relaxin to the clinic. The review then outlines the future directions as to where scientists and several pharmaceutical companies that have recognized the therapeutic potential of relaxin are working towards, to progress its development as a treatment for human patients suffering from various fibrotic diseases.

Custodiol® Supplemented with Synthetic Human Relaxin Decreases Ischemia-Reperfusion Injury after Porcine Kidney Transplantation

Objective. Ischemia-reperfusion injury (IRI) is inevitable after kidney transplantation (KT), impairing outcomes. Relaxin-2 (RLX) is a promising insulin-related peptide hormone that protects against renal IRI in rodents, although large animal models are needed before RLX can be tested in a human setting. Methods. In this blinded, randomized, and placebo-controlled experimental study kidneys from 19 donor pigs were retrieved after perfusion with Custodiol^® ± RLX (5 or 20 nmol/L) and underwent static cold storage (SCS) for 24 and 48 h, respectively. Subsequently, KT was performed after unilateral right nephrectomy. Study outcomes included markers for kidney function, oxidative stress, lipid peroxidation, and endothelial cell damage. PCR analysis for oxidative stress and apoptosis-related gene panels as well as immunohistochemistry were performed. Results. RLX upregulated SOD2 and NFKB expression to 135% (p = 0.042) and 125% (p = 0.019), respectively, while RIPK1 expression was downregulated to 82% (p = 0.016) of corresponding controls. Further RLX significantly downregulated RIPK1 and MLKL expression and decreased the number of Caspase 3- and MPO-positive cells in grafts after SCS. Conclusions. RLX supplemented Custodiol^® significantly decreased IRI via both antioxidant and anti-apoptotic mechanisms. Clinical trials are warranted to implement synthetic human RLX as a novel additive to preservation solutions against IRI.

Scutellarein relieves the death and inflammation of tubular epithelial cells in ischemic kidney injury by degradation of COX-2 protein

OBJECTIVES

Acute kidney injury (AKI) is a clinical syndrome that usually caused by ischemia/reperfusion (I/R). Previous studies have revealed the protection of scutellarein against ischemia in nervous system. This study aimed to demonstrate the potential of scutellarein in ischemic AKI.

METHODS

Animal model of ischemic AKI was established by clamping bilateral kidney pedicles in Sprague-Dawley rats. HK-2 cells were exposed to oxygen glucose deprivation/reoxygenation (OGD/R) to induce a cell model of AKI. The effects of scutellarein pre-treatment were detected by H&E staining, TUNEL, ELISA, CCK-8, LDH activity assay, ROS generation, flow cytometry, qRT-PCR and western blotting. Bioinformatic analysis was performed to probe the targets of scutellarein.

RESULTS

The blood urea nitrogen (BUN) and serum creatinine (SCr) levels in rats treated with scutellarein were lower than that in model groups. Scutellarein suppressed the pathological injury of kidney, and dose-dependently inhibited the apoptosis and pro-inflammatory cytokines release (IL-1β, IL-6 and IL-18). Scutellarein prevented OGD/R-induced HK-2 cell loss and cytotoxicity. ROS generation, apoptosis, and inflammation induced by OGD/R were all inhibited by scutellarein. By searching on the TCMSP and Symmap databases, COX-2 was screened out as a target of scutellarein. Scutellarein has no significant impacts on COX-2 mRNA expression, but could inhibit its protein level. Scutellarein promoted COX-2 protein degradation via enhancing autophagy. Furthermore, overexpression of COX-2 partly eliminated the renal protection of scutellarein in HK-2 cells.

CONCLUSIONS

Scutellarein was suggested as a renal protective agent against ischemia-induced damage in AKI. The protective properties of scutellarein may be through inhibition of COX-2.

Relaxin exerts a protective effect during ischemia-reperfusion in the rat model

BACKGROUND

Testicular torsion, which causes ischemia-reperfusion (IR) injury, is a serious urological emergency that can lead to testicular dysfunction, including infertility, primarily among newborn and pubertal males; thus, effective drugs should be administered during or after ischemia.

OBJECTIVES

Using a rat model of testicular IR injury, the present study investigated the protective effects of relaxin (RLN) against oxidative stress, testicular dysfunction, inflammation, histological damage, arrested spermatogenesis, and germ cell apoptosis as well as explored the usefulness of RLN as a potential protective drug for IR injury combined with surgical treatment.

MATERIALS AND METHODS

Male Sprague-Dawley rats were subjected to left testicular ischemia for 2 h, followed by 24 h of reperfusion. They were subsequently divided into three groups: sham, IR, and IR + RLN groups. Porcine RLN (500 ng/h) or saline was infused using an implanted osmotic mini-pump 90 min after inducing ischemia. The RLN dose used herein was that which resulted in serum RLN levels comparable to those in mid-pregnant rats based on previous studies.

RESULTS

Testicular IR increased germ cell apoptosis and histological damage as well as promoted disorganized and arrested spermatogenesis, accompanied by a significant increase in oxidative stress and inflammation. However, RLN administration ameliorated the adverse consequences associated with IR injury by attenuating oxidative stress and mitigating apoptosis and inflammation.

DISCUSSION AND CONCLUSION

The study findings clearly demonstrated that RLN exerts a protective effect against IR-induced testicular injury by attenuating oxidative stress, apoptosis, and inflammation, suggesting that RLN together with surgical treatment is a potentially efficacious approach toward ameliorating testicular dysfunction following testicular torsion.

Anti-apoptotic and Matrix Remodeling Actions of a Small Molecule Agonist of the Human Relaxin Receptor, ML290 in Mice With Unilateral Ureteral Obstruction

Diseases, such as diabetes and hypertension, often lead to chronic kidney failure. The peptide hormone relaxin has been shown to have therapeutic effects in various organs. In the present study, we tested the hypothesis that ML290, a small molecule agonist of the human relaxin receptor (RXFP1), is able to target the kidney to remodel the extracellular matrix and reduce apoptosis induced by unilateral ureteral obstruction (UUO). UUO was performed on the left kidney of humanized RXFP1 mice, where the right kidneys served as contralateral controls. Mice were randomly allocated to receive either vehicle or ML290 (30 mg/kg) via daily intraperitoneal injection, and kidneys were collected for apoptosis, RNA, and protein analyses. UUO significantly increased expression of pro-apoptotic markers in both vehicle- and ML290-treated mice when compared to their contralateral control kidneys. Specifically, Bax expression and Erk1/2 activity were upregulated, accompanied by an increase of TUNEL-positive cells in the UUO kidneys. Additionally, UUO induced marked increase in myofibroblast differentiation and aberrant remodeling on the extracellular matrix. ML290 suppressed these processes by promoting a reduction of pro-apoptotic, fibroblastic, and inflammatory markers in the UUO kidneys. Finally, the potent effects of ML290 to remodel the extracellular matrix were demonstrated by its ability to reduce collagen gene expression in the UUO kidneys. Our data indicate that daily administration of ML290 has renal protective effects in the UUO mouse model, specifically through its anti-apoptotic and extracellular matrix remodeling properties.

Combining mesenchymal stem cells with serelaxin provides enhanced renoprotection against 1K/DOCA/salt-induced hypertension

BACKGROUND AND PURPOSE

Fibrosis is a hallmark of chronic kidney disease (CKD) that significantly contributes to renal dysfunction, and impairs the efficacy of stem cell-based therapies. This study determined whether combining bone marrow-derived mesenchymal stem cells (BM-MSCs) with the renoprotective effects of recombinant human relaxin (serelaxin) could therapeutically reduce renal fibrosis in mice with one kidney/deoxycorticosterone acetate/salt (1K/DOCA/salt)-induced hypertension, compared with the effects of the ACE inhibitor, perindopril.

EXPERIMENTAL APPROACH

Adult male C57BL/6 mice were uni-nephrectomised and received deoxycorticosterone acetate and saline to drink (1K/DOCA/salt) for 21 days. Control mice were uni-nephrectomised but received water over the same time period. Sub-groups of 1K/DOCA/salt-injured mice (n = 5-8 per group) were treated with either serelaxin (0.5 mg·kg^-1 ·day^-1 ) or BM-MSCs (1 × 10⁶ per mouse) alone; both treatments combined (with 0.5 × 10⁶ or 1 × 10⁶ BM-MSCs per mouse); or perindopril (2 mg·kg^-1 ·day^-1 ) from days 14-21.

KEY RESULTS

1K/DOCA/salt-injured mice developed elevated BP and hypertension-induced renal damage, inflammation and fibrosis. BM-MSCs alone reduced the injury-induced fibrosis and attenuated BP to a similar extent as perindopril. Serelaxin alone modestly reduced renal fibrosis and effectively reduced tubular injury. Strikingly, the combined effects of BM-MSCs (at both doses) with serelaxin significantly inhibited renal fibrosis and proximal tubular epithelial injury while restoring renal architecture, to a greater extent than either therapy alone, and over the effects of perindopril.

CONCLUSION AND IMPLICATIONS

Combining BM-MSCs and serelaxin provided broader renoprotection over either therapy alone or perindopril and might represent a novel treatment for hypertensive CKD.

Relaxin peptides reduce cellular damage in cultured brain slices exposed to transient oxygen–glucose deprivation: an effect mediated by nitric oxide

The effect of treatment with human relaxins on cell death was studied in oxygen- and glucose-deprived brain slices. In addition, involvement of nitric oxide and the relaxin receptor, RXFP3, was studied. Brain slices ( n = 12–18/group) were cultured under standard conditions for two weeks and then exposed to: ( i) an oxygenated balanced salt solution, ( ii) a deoxygenated, glucose-free balanced salt solution (OGD media), or ( iii) OGD media containing 10−7 mol/L H2 relaxin, 10−7 mol/L H2 relaxin with 50 μmol/L L-NIL, 10−7 mol/L H3 relaxin, or 10−7 mol/L H3 relaxin with 50 μmol/L L-NIL. Cell death was assessed using propidium iodide fluorescence. In a separate experiment, 10−5 mol/L R3 B1-22R (an antagonist of RXFP3) was added to both H2 and H3 relaxin treatments. H2 and H3 relaxin treatment reduced cell damage or death in OGD slices and L-NIL partially attenuated the effect of H3 relaxin. Antagonism of RXFP3 blocked the effect of H3 but not H2 relaxin. These data increase our understanding of the role of relaxin ligands and their receptors in protecting tissues throughout the body from ischemia and reperfusion injury.

Ellagic Acid Ameliorates Renal Ischemic-Reperfusion Injury Through NOX4/JAK/STAT Signaling Pathway

Ellagic acid (EA), a natural polyphenolic compound, has been proved to possess multiple biological activities including alleviating ischemic-reperfusion (I/R) injury. The aim of this current study was to investigate whether EA alleviates I/R injury via regulating inflammatory signaling pathway. Rats were subjected to ischemic-reperfusion (I/R) injury and given orally with different doses of EA before surgery. H&E staining, ELISA assay, and biochemical index analysis were performed to evaluate renal injury and inflammatory factors. Oxidative stress level was detected by DCFH-DA staining and corresponding assay kits. In addition, TUNEL assay and flow cytometric assay were applied for exploring the apoptosis of tissue and cells, respectively. Western blot assay was used to assess protein expressions in tissue and cells. The results showed that EA attenuated the renal I/R injury and reserved renal cell function in vivo. The levels of TNF-a, IL-1β, IL-6, and MCP-1, oxidative stress level, and apoptosis were suppressed in EA-treated rats. Mechanistic studies showed that EA suppressed the phosphorylation of JAK1, JAK2, and STAT1 and reduced the NOX4 level. EA reduced apoptosis, hypoxia-induced inflammatory response, and ROS levels. Moreover, overexpression of NOX4 reversed the protective function with NOX4 inhibition, indicating that the effect of EA against renal IRI or cell hypoxia/reoxygenation might mainly depend on NOX4. The results suggest that EA exerts the renoprotective effect via suppressing NOX4/JAK/STAT signaling pathway, which may be a novel potential therapy for the treatment of acute kidney injury in clinic.

Efficacy of relaxin for cisplatin-induced testicular dysfunction and epididymal spermatotoxicity

Background

Cisplatin (CP) is an extremely effective anticancer agent widely used to treat various cancer types, however, the potential side effects include testicular dysfunction. This study was to investigate, using a rat model of CP-induced testicular dysfunction, the protective effects of relaxin (RLN) against oxidative stress, testicular function, histological damage, spermatogenesis, germ-cell apoptosis, and sperm output, and to explore the usefulness of RLN as a potential protective drug for use with CP in chemotherapeutic treatments.

Methods

Sprague-Dawley male rats were used, which were divided into three groups: sham control, CP, and CP + RLN. Porcine RLN (500 ng/h) or saline was infused for 5 days using an implanted osmotic mini-pump following intraperitoneal injection of CP (6 mg/kg). RLN dose was chosen based on previous studies showing that it resulted in serum relaxin levels comparable to those in rats at the middle of pregnancy. At 5 days after CP administration, samples were collected and assessment of testicular histopathology, germ-cell apoptosis, oxidative stress, lipid peroxidation, and sperm quality was performed as main measures.

Results

The testicular CP model showed reduced testis weight and significantly decreased spermatogenesis scores. Additionally, CP administration induced a 4.6-fold increase in the apoptotic index associated with a significant increase in oxidative stress and upregulation of pro-apoptotic Casp3 and downregulation of anti-apoptotic Bcl2 levels, resulting in a marked reduction in sperm concentration. However, RLN administration caused a significant reduction in CP-mediated damage by attenuating oxidative stress and cell apoptosis. RLN administration efficiently scavenged ROS via the activation of SOD, CAT, and GPx and upregulation of GSH to prevent lipid peroxidation and decreased apoptosis by altering Bcl2 and Casp3 expression, thereby reducing histopathological damage and restoring spermatogenesis. Furthermore, RLN ameliorated attenuated sperm motility in the cauda epididymis resulting from CP treatment.

Conclusions

This study clearly indicates that RLN exerts a protective effect against CP-induced testicular damage through attenuation of oxidative stress and suppression of apoptosis. Our findings suggest RLN as a potentially efficacious drug for use with cisplatin chemotherapy in order to ameliorate CP-induced side effects and testicular injury adversely affecting spermatogenesis, sperm quality, and oxidative-stress parameters.

Relaxin Positively Influences Ischemia-Reperfusion Injury in Solid Organ Transplantation: A Comprehensive Review

In recent decades, solid organ transplantation (SOT) has increased the survival and quality of life for patients with end-stage organ failure by providing a potentially long-term treatment option. Although the availability of organs for transplantation has increased throughout the years, the demand greatly outweighs the supply. One possible solution for this problem is to extend the potential donor pool by using extended criteria donors. However, organs from such donors are more prone to ischemia reperfusion injury (IRI) resulting in higher rates of delayed graft function, acute and chronic graft rejection and worse overall SOT outcomes. This can be overcome by further investigating donor preconditioning strategies, graft perfusion and storage and by finding novel therapeutic agents that could reduce IRI. relaxin (RLX) is a peptide hormone with antifibrotic, antioxidant, anti-inflammatory and cytoprotective properties. The main research until now focused on heart failure; however, several preclinical studies showed its potentials for reducing IRI in SOT. The aim of this comprehensive review is to overview currently available literature on the possible role of RLX in reducing IRI and its positive impact on SOT.

NR4A1 silencing protects against renal ischemia-reperfusion injury through activation of the β-catenin signaling pathway in old mice

Renal ischemia-reperfusion injury (IRI), a major cause of acute kidney injury as well as a contributor to a rapid kidney dysfunction and high mortality rates, is a complex yet not fully understood process. Investigation on the underlying molecular mechanism including the inflammation initiation and progression can help to have a better understanding of the disease, and thereby lead to a potential therapeutic approach. We established renal IRI mouse model groups differing in their ages. These renal IRI mice were treated either only with si-nuclear receptor subfamily 4, group A, member 1 (NR4A1) or together with si-β-catenin by tail vein injection to analyze the role of NR4A1 and β-catenin in the development of renal IRI. Serum creatinine (SCr) and blood urea nitrogen (BUN) levels were examined for renal function analysis. Levels of the apoptosis markers B-cell lymphoma-2 (Bcl-2), Bcl-2 associated protein X (Bax), and cleaved caspase-3 were determined. NR4A1 gene was up-regulated in the renal tissues of all mice with IRI, which showed a much higher level in the old mice with IRI. si-NR4A1 treatment resulted in reduced SCr and BUN levels and a decrease of cell apoptosis, indicated by lower expression of Bax and cleaved Caspase-3, while in contrast increased levels of Bcl-2 were detected. Interestingly, also the β-catenin level was increased by knockdown of NR4A1. Furthermore, si-β-catenin reversed the effect of knockdown of NR4A1, leading to aggravated renal function damage, severe pathological injury and increased apoptosis. Thus, silencing NR4A1 ameliorates renal IRI via β-catenin signaling pathway activation. Down-regulated NR4A1 confirms renoprotective properties against renal IRI via the activation of β-catenin signaling pathway in old mice.

Relaxin and extracellular matrix remodeling: Mechanisms and signaling pathways

Fibrosis is associated with accumulation of excess fibrillar collagen, leading to tissue dysfunction. Numerous processes, including inflammation, myofibroblast activation, and endothelial-to-mesenchymal transition, play a role in the establishment and progression of fibrosis. Relaxin is a peptide hormone with well-known antifibrotic properties that result from its action on numerous cellular targets to reduce fibrosis. Relaxin activates multiple signal transduction pathways as a mechanism to suppress inflammation and myofibroblast activation in fibrosis. In this review, the general mechanisms underlying fibrotic diseases are described, along with the current state of knowledge regarding cellular targets of relaxin. Finally, an overview is presented summarizing the signaling pathways activated by relaxin and other relaxin family peptide receptor agonists to suppress fibrosis.

Inhibition of ubiquitin-activating enzyme protects against organ injury after intestinal ischemia-reperfusion

Intestinal ischemia-reperfusion (I/R) occurs in various clinical settings, such as transplantation, acute mesenteric arterial occlusion, trauma, and shock. I/R injury causes severe systemic inflammation, leading to multiple organ dysfunction associated with high mortality. The ubiquitin proteasome pathway has been indicated in the regulation of inflammation, particularly through the NF-κB signaling pathway. PYR-41 is a small molecular compound that selectively inhibits ubiquitin-activating enzyme E1. A mouse model of intestinal I/R injury by clamping the superior mesenteric artery for 45 min was performed to evaluate the effect of PYR-41 treatment on organ injury and inflammation. PYR-41 was administered intravenously at the beginning of reperfusion. Blood and organ tissues were harvested at 4 h after reperfusion. PYR-41 treatment improved the morphological structure of gut and lung after I/R, as judged by hematoxylin and eosin staining. It also reduced the number of apoptotic terminal deoxynucleotidyl transferase dUTP nick end-labeling-positive cells and caspase-3 activity in the organs. PYR-41 treatment decreased the expression of proinflammatory cytokines IL-6 and IL-1β as well as chemokines keratinocyte chemoattractant and macrophage inflammatory protein-2 in the gut and lung, which leads to inhibition of neutrophils infiltrating into these organs. The serum levels of IL-6, aspartate aminotransferase, and lactate dehydrogenase were reduced by the treatment. The IκB degradation in the gut increased after I/R was inhibited by PYR-41 treatment. Thus, ubiquitination may be a potential therapeutic target for treating patients suffering from intestinal I/R. NEW & NOTEWORTHY Excessive inflammation contributes to organ injury from intestinal ischemia-reperfusion (I/R) in many clinical conditions. NF-κB signaling is very important in regulating inflammatory response. In an experimental model of gut I/R injury, we demonstrate that administration of a pharmacological inhibitor of ubiquitination process attenuates NF-κB activation, leading to reduction of inflammation, tissue damage, and apoptosis in the gut and lungs. Therefore, ubiquitination process may serve as a therapeutic target for treating patients with intestinal I/R injury.

Evaluation and physiopathology of minor transient shock wave lithotripsy - induced renal injury based on urinary biomarkers levels

Introduction

Extracorporeal shock wave lithotripsy (ESWL) is one of the most useful methods available for the treatment of urolithiasis. However, despite its significant benefits, adverse effects can occur. Oxidative stress mediated by ischemia-reperfusion might contribute to kidney injury after ESWL. Moreover, an acute kidney injury (AKI) may develop. AKI is typically diagnosed by measuring serum creatinine level, yet serum creatinine does not allow for early detection of sub-clinical AKI. The latest report has investigated multiple ways to determine ESWL - induced renal damage through the evaluation of various urine biomarkers of renal injury.

Materials and methods

The Medline and Web of Science databases were searched without a time limit in November 2017 using the terms 'ESWL' in conjunction with 'kidney failure', 'kidney damage', 'renal injury' and 'inflammation markers', 'biomarkers'. Boolean operators (NOT, AND, OR) were also used in succession to narrow and broaden the search. In this review, we described all the up-to-date reported urine markers of ESWL-induced renal damage.

Results

In recent years, several studies demonstrated evaluation of ESWL - induced renal injury based on urinary biomarkers levels and its utility in clinical practice. They have a beneficial role in the early detection of AKI, as well as in observation of a transition of this acute illness into chronic kidney disease.

Conclusions

Different markers have been evaluated in the urine before and after the ESWL treatment, but their number is still limited and results remain inconclusive. Further investigations are mandatory.

Peptide hormone relaxin: from bench to bedside

The peptide hormone relaxin has numerous roles both within and independent of pregnancy and is often thought of as a “pleiotropic hormone.” Relaxin targets several tissues throughout the body, and has many functions associated with extracellular matrix remodeling and the vasculature. This review considers the potential therapeutic applications of relaxin in cervical ripening, in vitro fertilization, preeclampsia, acute heart failure, ischemia-reperfusion, and cirrhosis. We first outline the animal models used in preclinical studies to progress relaxin into clinical trials and then discuss the findings from these studies. In many cases, the positive outcomes from preclinical animal studies were not replicated in human clinical trials. Therefore, the focus of this review is to evaluate the various animal models used to develop relaxin as a potential therapeutic and consider the limitations that must be addressed in future studies. These include the use of human relaxin in animals, duration of relaxin treatment, and the appropriateness of the clinical conditions being considered for relaxin therapy.

Ischemic stroke and select adipose-derived and sex hormones: a review

Ischemic stroke is the fifth leading cause of death in the USA and is the leading cause of serious, long-term disability worldwide. The principle sex hormones (estrogen, progesterone, and testosterone), both endogenous and exogenous, have profound effects on various stroke outcomes and have become the focus of a number of studies evaluating risk factors and treatment options for ischemic stroke. In addition, the expression of other hormones that may influence stroke outcome, including select adipose-derived hormones (adiponectin, leptin, and ghrelin), can be regulated by sex hormones and are also the focus of several ischemic stroke studies. This review aims to summarize some of the preclinical and clinical studies investigating the principle sex hormones, as well as select adipose-derived hormones, as risk factors or potential treatments for ischemic stroke. In addition, the potential for relaxin, a lesser studied sex hormone, as a novel treatment option for ischemic stroke is explored.

Quantification of Relaxin-2 Connecting Peptide (Pro-RLX2) in Human Blood Samples

BACKGROUND

The peptide hormone relaxin-2 is implicated in diverse physiological and pathophysiological processes. Several assays are available for quantification of human relaxin-2, but because stability of the mature peptide in serum is limited, measurement of the more stable connecting peptide (pro-RLX2) might be beneficial.

METHODS

Pro-RLX2 was measured in a sandwich immunoluminometric assay using 2 monoclonal antibodies. The concentration of pro-RLX2 was detected in healthy pregnant (n = 100) and healthy male and nonpregnant female (n = 81) subjects and compared with the concentration of mature relaxin-2 in a subset of samples.

RESULTS

The pro-RLX2 immunoassay has an analytical and functional assay sensitivity (FAS) of 1.59 pmol/L and 1.7 pmol/L, respectively. The analyte is stable in EDTA plasma samples for 8 days at room temperature, dilutes in a linear fashion, and recovery was 103%. The assay system is not biased by common interfering substances. Measurement of 80% of plasma samples from healthy males and females is below the FAS {median 1.49 pmol/L [interquartile range (IQR) of 0.925-2.14 pmol/L]}, and no concentration difference between male and nonpregnant female plasma samples was observed. The median plasma concentration in healthy pregnant women is increased up to 562 pmol/L (IQR 341-789 pmol/L). During pregnancy, pro-RLX2 concentrations decrease with increasing gestation. The correlation coefficient with the R&D assay for mature relaxin-2 was 0.96 (P < 0.0001).

CONCLUSION

Pro-RLX2 is stable in plasma of healthy individuals. Although samples of pregnant women are reliably measurable, most samples from healthy nonpregnant women and men are below the detection limit. Determination of pro-RLX2 concentrations might indicate rate of synthesis of relaxin-2 during pregnancy and therapeutic application of recombinant relaxin (Serelaxin).

The optimal duration of ischemic preconditioning for renal ischemia-reperfusion injury in mice

Purpose

The aim of the present study was to investigate the protective effects of ischemic preconditioning for different periods of time and to elucidate the optimal safe ischemic preconditioning time for renal ischemia-reperfusion (I/R) injury in mice.

Methods

A total of 25 male C57BL/6 mice were randomly divided into 5 groups (sham, I/R, ischemic preconditioning [IP]-3, IP-5, and IP-7 groups), in which the kidney was preconditioned with IP of various durations and then subjected to I/R injury (the last 3 groups). To induce renal ischemia, the left renal pedicle was occluded with a nontraumatic microaneurysm clamp for 30 minutes followed by reperfusion for 24 hours. The effects of IP on renal I/R injury were evaluated in terms of renal function, tubular necrosis, apoptotic cell death and inflammatory cytokines.

Results

Results indicated that BUN and creatinine (Cr) levels increased significantly in the I/R group, but the elevations were significantly lower in IP groups, especially in the IP-5 group. Histological analysis revealed that kidney injury was markedly decreased in the IP-5 group compared with the I/R group, as evidenced by reduced renal necrosis/apoptosis. In addition, IP significantly inhibited gene expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and chemokines (monocyte chemoattractant protein-1). Western blot analysis indicated that the expression levels of Toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) were upregulated in the I/R group, while expression was inhibited in the IP groups.

Conclusion

Five-minute IP had the greatest protective effect against I/R injury.

Serelaxin improves cardiac and renal function in DOCA-salt hypertensive rats

Serelaxin, a recombinant form of the naturally occurring peptide hormone relaxin-2, is a pleiotropic vasodilating hormone that has been studied in patients with acute heart failure. In this study, the effects of serelaxin on cardiac and renal function, fibrosis, inflammation and lipid accumulation were studied in DOCA-salt treated rats. Uninephrectomized rats were assigned to two groups: controls provided with normal drinking water and DOCA provided with DOCA pellets and sodium chloride drinking water. After 4 weeks, the DOCA-salt rats were randomly selected and implanted with osmotic minipumps delivering vehicle or serelaxin for another 4 weeks. Treatment with serelaxin prevented cardiac and renal dysfunction in DOCA-salt rats. Serelaxin prevented cardiac and renal fibrosis, as determined by Picrosirius Red staining and Second Harmonic Generation (SHG) Microscopy. Treatment of DOCA-salt rats with serelaxin decreased renal inflammation, including the expression of TGF-β, NFκB, MCP-1, IL-1, IL-6, ICAM-1, VCAM-1 and CD68 macrophages. Serelaxin also decreased lipid accumulation in kidney in part by decreasing SREBP-1c, SREBP-2, ChREBP, FATP1, HMGCoAR, and LDL receptor, and increasing Acox1 and ABCA1. In summary, serelaxin reversed DOCA-salt induced cardiac and renal dysfunction.

Effect of endurance training and branched-chain amino acids on the signaling for muscle protein synthesis in CKD model rats fed a low-protein diet

A low-protein diet (LPD) protects against the progression of renal injury in patients with chronic kidney disease (CKD). However, LPD may accelerate muscle wasting in these patients. Both exercise and branched-chain amino acids (BCAA) are known to increase muscle protein synthesis by activating the mammalian target of rapamycin (mTOR) pathway. The aim of this study was to investigate whether endurance exercise and BCAA play a role for increasing muscle protein synthesis in LPD-fed CKD (5/6 nephrectomized) rats. Both CKD and sham rats were pair-fed on LPD or LPD fortified with a BCAA diet (BD), and approximately one-half of the animals in each group was subjected to treadmill exercise (15 m/min, 1 h/day, 5 days/wk). After 7 wk, renal function was measured, and soleus muscles were collected to evaluate muscle protein synthesis. Renal function did not differ between LPD- and BD-fed CKD rats, and the treadmill exercise did not accelerate renal damage in either group. The treadmill exercise slightly increased the phosphorylation of p70s6 kinase, a marker of mTOR activity, in the soleus muscle of LPD-fed CKD rats compared with the sham group. Furthermore, BCAA supplementation of the LPD-fed, exercise-trained CKD rats restored the phosphorylation of p70s6 kinase to the same level observed in the sham group; however, the corresponding induced increase in muscle protein synthesis and muscle mass was marginal. These results indicate that the combination of treadmill exercise and BCAA stimulates cell signaling to promote muscle protein synthesis; however, the implications of this effect for muscle growth remain to be clarified.

Anti-fibrotic actions of relaxin

Fibrosis refers to the hardening or scarring of tissues that usually results from aberrant wound healing in response to organ injury, and its manifestations in various organs have collectively been estimated to contribute to around 45-50% of deaths in the Western world. Despite this, there is currently no effective cure for the tissue structural and functional damage induced by fibrosis-related disorders. Relaxin meets several criteria of an effective anti-fibrotic based on its specific ability to inhibit pro-fibrotic cytokine and/or growth factor-mediated, but not normal/unstimulated, fibroblast proliferation, differentiation and matrix production. Furthermore, relaxin augments matrix degradation through its ability to up-regulate the release and activation of various matrix-degrading matrix metalloproteinases and/or being able to down-regulate tissue inhibitor of metalloproteinase activity. Relaxin can also indirectly suppress fibrosis through its other well-known (anti-inflammatory, antioxidant, anti-hypertrophic, anti-apoptotic, angiogenic, wound healing and vasodilator) properties. This review will outline the organ-specific and general anti-fibrotic significance of exogenously administered relaxin and its mechanisms of action that have been documented in various non-reproductive organs such as the cardiovascular system, kidney, lung, liver, skin and tendons. In addition, it will outline the influence of sex on relaxin's anti-fibrotic actions, highlighting its potential as an emerging anti-fibrotic therapeutic.

LINKED ARTICLES

This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.

Relaxin Attenuates Contrast-Induced Human Proximal Tubular Epithelial Cell Apoptosis by Activation of the PI3K/Akt Signaling Pathway In Vitro

Background. Contrast-induced acute kidney injury (CI-AKI) is one of the main causes of iatrogenic acute kidney injury (AKI); however, therapeutic strategies for AKI remain limited. This study aims to explore the effect of relaxin (RLX) on contrast-induced HK-2 apoptosis and its underlying mechanisms. Methods. Renal tubular epithelial cells (HK-2) were incubated either with or without ioversol, human H2 relaxin, and LY294002 (the inhibitor of the PI3K/Akt signal pathway). Cell viability was evaluated with a CCK-8 assay. Apoptotic morphologic alterations were observed using the Hoechst 33342 staining method. Apoptosis was detected with Annexin V staining. Western blot analysis was employed to measure the expression of pAkt (S473), Akt, cleaved caspase-3, Bcl-2, Bax, and actin proteins. Results. Ioversol reduced the viability of HK-2 cells. Western blotting results revealed decreased expression of phosphorylated Akt in cells treated with ioversol. The activities of caspase-3 and Bax protein increased, while the expression of Bcl-2 protein decreased. As a result, the Bax/Bcl-2 ratio increased after treatment with ioversol. These effects were reversed when HK-2 cells were cotreated with RLX. However, with preadministration of PI3K/Akt pathway inhibitor LY294002, the effect of RLX was blocked. Conclusion. Our study demonstrates that relaxin attenuates ioversol induced cell apoptosis via activation of the PI3K/Akt signaling pathway, suggesting that RLX might play a protective role in the treatment of CI-AKI.

The actions of relaxin on the human cardiovascular system

The insulin-like peptide relaxin, originally identified as a hormone of pregnancy, is now known to exert a range of pleiotropic effects including vasodilatory, anti-fibrotic, angiogenic, anti-apoptotic and anti-inflammatory effects in both males and females. Relaxin produces these effects by binding to a cognate receptor RXFP1 and activating a variety of signalling pathways including cAMP, cGMP and MAPKs as well as by altering gene expression of TGF-β, MMPs, angiogenic growth factors and endothelin receptors. The peptide has been shown to be effective in halting or reversing many of the adverse effects including fibrosis in animal models of cardiovascular disease including ischaemia/reperfusion injury, myocardial infarction, hypertensive heart disease and cardiomyopathy. Relaxin given to humans is safe and produces favourable haemodynamic changes. Serelaxin, the recombinant form of relaxin, is now in extended phase III clinical trials for the treatment of acute heart failure. Previous clinical studies indicated that a 48 h infusion of relaxin improved 180 day mortality, yet the mechanism underlying this effect is not clear. This article provides an overview of the cellular mechanism of effects of relaxin and summarizes its beneficial actions in animal models and in the clinic. We also hypothesize potential mechanisms for the clinical efficacy of relaxin, identify current knowledge gaps and suggest new ways in which relaxin could be useful therapeutically.

LINKED ARTICLES

This article is part of a themed section on Recent Progress in the Understanding of Relaxin Family Peptides and their Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.10/issuetoc.

Renoprotective approaches and strategies in acute kidney injury

Acute kidney injury (AKI) is a major renal disease associated with high mortality rate and increasing prevalence. Decades of research have suggested numerous chemical and biological agents with beneficial effects in AKI. In addition, cell therapy and molecular targeting have been explored for reducing kidney tissue damage and promoting kidney repair or recovery from AKI. Mechanistically, these approaches may mitigate oxidative stress, inflammation, cell death, and mitochondrial and other organellar damage, or activate cytoprotective mechanisms such as autophagy and pro-survival factors. However, none of these findings has been successfully translated into clinical treatment of AKI. In this review, we analyze these findings and propose experimental strategies for the identification of renoprotective agents or methods with clinical potential. Moreover, we propose the consideration of combination therapy by targeting multiple targets in AKI.

The Anti-fibrotic Actions of Relaxin Are Mediated Through a NO-sGC-cGMP-Dependent Pathway in Renal Myofibroblasts In Vitro and Enhanced by the NO Donor, Diethylamine NONOate

INTRODUCTION

The anti-fibrotic hormone, relaxin, has been inferred to disrupt transforming growth factor (TGF)-β1/Smad2 phosphorylation (pSmad2) signal transduction and promote collagen-degrading gelatinase activity via a nitric oxide (NO)-dependent pathway. Here, we determined the extent to which NO, soluble guanylate cyclase (sGC) and cyclic guanosine monophosphate (cGMP) were directly involved in the anti-fibrotic actions of relaxin using a selective NO scavenger and sGC inhibitor, and comparing and combining relaxin's effects with that of an NO donor.

METHODS AND RESULTS

Primary renal cortical myofibroblasts isolated from injured rat kidneys were treated with human recombinant relaxin (RLX; 16.8 nM), the NO donor, diethylamine NONOate (DEA/NO; 0.5-5 μM) or the combined effects of RLX (16.8 nM) and DEA/NO (5 μM) over 72 h. The effects of RLX (16.8 nM) and DEA/NO (5 μM) were also evaluated in the presence of the NO scavenger, hydroxocobalamin (HXC; 100 μM) or sGC inhibitor, ODQ (5 μM) over 72 h. Furthermore, the effects of RLX (30 nM), DEA/NO (5 μM) and RLX (30 nM) + DEA/NO (5 μM) on cGMP levels were directly measured, in the presence or absence of ODQ (5 μM). Changes in matrix metalloproteinase (MMP)-2, MMP-9 (cell media), pSmad2 and α-smooth muscle actin (α-SMA; a measure myofibroblast differentiation) (cell layer) were assessed by gelatin zymography and Western blotting, respectively. At the highest concentration tested, both RLX and DEA/NO promoted MMP-2 and MMP-9 levels by 25-33%, while inhibiting pSmad2 and α-SMA expression by up to 50% (all p < 0.05 vs. untreated and vehicle-treated cells). However, 5μM of DEA/NO was required to produce the effects seen with 16.8 nM of RLX over 72 h. The anti-fibrotic effects of RLX or DEA/NO alone were completely abrogated by HXC and ODQ (both p < 0.01 vs. RLX alone or DEA/NO alone), but were significantly enhanced when added in combination (all p < 0.05 vs. RLX alone). Additionally, the direct cGMP-promoting effects of RLX, DEA/NO and RLX+DEA/NO (which all increased cGMP levels by 12-16-fold over basal levels; all p < 0.01 vs. vehicle-treated cells) were significantly inhibited by pre-treatment of ODQ (all p < 0.05 vs. the respective treatments alone).

CONCLUSION

These findings confirmed that RLX mediates its TGF-β1-inhibitory and gelatinase-promoting effects via a NO-sGC-cGMP-dependent pathway, which was additively augmented by co-administration of DEA/NO.

Serelaxin for the treatment of acute heart failure: a review with a focus on end-organ protection

Acute heart failure (AHF) is a complex clinical syndrome characterized by fluid overload and haemodynamic abnormalities (short-term clinical consequences) and the development of end-organ damage (long-term consequences). Current therapies for the treatment of AHF, such as loop diuretics and vasodilators, help to relieve haemodynamic imbalance and congestion, but have not been shown to prevent (and may even contribute to) end-organ damage, or to provide long-term clinical benefit. Serelaxin is the recombinant form of human relaxin-2, a naturally occurring hormone involved in mediating haemodynamic changes during pregnancy. Preclinical and clinical studies have investigated the effects mediated by serelaxin and the suitability of this agent for the treatment of patients with AHF. Data suggest that serelaxin acts via multiple pathways to improve haemodynamics at the vascular, cardiac, and renal level and provide effective congestion relief. In addition, this novel agent may protect the heart, kidneys, and liver from damage by inhibiting inflammation, oxidative stress, cell death, and tissue fibrosis, and stimulating angiogenesis. Serelaxin may therefore improve both short- and long-term outcomes in patients with AHF. In this review, we examine the unique mechanisms underlying the potential benefits of serelaxin for the treatment of AHF, in particular, those involved in mediating end-organ protection.

International Union of Basic and Clinical Pharmacology. XCV. Recent advances in the understanding of the pharmacology and biological roles of relaxin family peptide receptors 1-4, the receptors for relaxin family peptides

Relaxin, insulin-like peptide 3 (INSL3), relaxin-3, and INSL5 are the cognate ligands for the relaxin family peptide (RXFP) receptors 1-4, respectively. RXFP1 activates pleiotropic signaling pathways including the signalosome protein complex that facilitates high-sensitivity signaling; coupling to Gα(s), Gα(i), and Gα(o) proteins; interaction with glucocorticoid receptors; and the formation of hetero-oligomers with distinctive pharmacological properties. In addition to relaxin-related ligands, RXFP1 is activated by Clq-tumor necrosis factor-related protein 8 and by small-molecular-weight agonists, such as ML290 [2-isopropoxy-N-(2-(3-(trifluoromethylsulfonyl)phenylcarbamoyl)phenyl)benzamide], that act allosterically. RXFP2 activates only the Gα(s)- and Gα(o)-coupled pathways. Relaxin-3 is primarily a neuropeptide, and its cognate receptor RXFP3 is a target for the treatment of depression, anxiety, and autism. A variety of peptide agonists, antagonists, biased agonists, and an allosteric modulator target RXFP3. Both RXFP3 and the related RXFP4 couple to Gα(i)/Gα(o) proteins. INSL5 has the properties of an incretin; it is secreted from the gut and is orexigenic. The expression of RXFP4 in gut, adipose tissue, and β-islets together with compromised glucose tolerance in INSL5 or RXFP4 knockout mice suggests a metabolic role. This review focuses on the many advances in our understanding of RXFP receptors in the last 5 years, their signal transduction mechanisms, the development of novel compounds that target RXFP1-4, the challenges facing the field, and current prospects for new therapeutics.

Dioscin attenuates renal ischemia/reperfusion injury by inhibiting the TLR4/MyD88 signaling pathway via up-regulation of HSP70

We previously reported the effect of dioscin against hepatic ischemia/reperfusion injury (IRI) in rats. However, little is known concerning the role of dioscin in renal IRI. In the present study, rats were subjected to IRI and dioscin was intragastrically administered for seven consecutive days before surgery. In vitro models of hypoxia/reoxygenation were developed in NRK-52E and HK-2 cells, which were prophylactically treated with or without dioscin. The results showed that dioscin significantly decreased serum BUN and Cr levels, and markedly attenuated cell injury. Mechanistic studies showed that dioscin significantly increased HSP70 levels, decreased the levels of TLR4, MyD88, TRAF6, COX-2, JNK, ERK and p38 MAPK phosphorylation, suppressed the nuclear translocation of NF-κB and HMGB1, and subsequently decreased the mRNA levels of IL-1β, IL-6, TNF-α, ICAM-1 and IFN-γ. Moreover, HSP70 siRNA or TLR4 DNA reversed the nephroprotective effects of dioscin, while dioscin still significantly down-regulated the TLR4 signaling pathway. Furthermore, by inhibiting MyD88 with ST2825 (a MyD88 inhibitor), renal IRI was significantly attenuated, suggesting that the effect of dioscin against renal IRI depended on MyD88. Our results suggested that dioscin had a potent effect against renal IRI through suppressing the TLR4/MyD88 signaling pathway by up-regulating HSP70. These data provide new insights for investigating the natural product with the nephroprotective effect against IRI, which should be developed as a new therapeutic agent for the treatment of acute kidney injury in the future.

Shock wave induces biological renal damage by activating excessive inflammatory responses in rat model

The study was aimed to investigate the potential mechanism of inflammatory renal damage induced by shock wave. A total of 48 rats, with the right kidney cut, are randomly assigned into control group, ESWL group and ESWL + PDTC group. Rats were treated with shock wave at the left kidney. At post-shock wave 3 and 105 days, all the animals were sacrificed for detecting the expression of tumor necrosis factor (TNF)-α, intercellular adhesion molecule (ICAM)-1, and monocyte chemoattractant protein (MCP)-1. The inflammatory responses were evaluated by detecting the level of myeloperoxidase (MPO) and ED-1. The histological renal injury was also examined. Before the animals were sacrificed, the urine samples were collected for measuring the values of malondialdehyde (MDA), β2-microglobulin, interleukin (IL)-6, and IL-18. At post-shock wave 3 days, the higher expression of ICAM-1 and TNF-α were observed in shock wave-treated kidneys. The level of urine TNF-α, IL-6, and IL-18 were also increased significantly. Using PDTC obviously decreased the expression of ICAM-1 and TNF-α. It also effectively inhibited the degree of oxidative stress and neutrophil infiltration. At post-shock wave 105 days, the expression of MCP-1 and the level of urine β2-microglobulin and IL-18 were increased significantly. The histological analysis also indicated more ED-1-positive cells and serious fibrosis in shock wave-treated kidneys. PDTC significantly suppressed MCP-1 and IL-18 expression, decreased monocyte infiltration, and alleviate the degree of interstitium fibrosis. Shock wave triggered excessive inflammatory responses and aggravated renal biological damage. Several inflammatory factors including ICAM-1, MCP-1, and TNF-α were considered to play important role in this type of renal damage.

Protective effects of relaxin against cisplatin-induced nephrotoxicity in rats

BACKGROUND

Cisplatin (CDDP)-induced acute kidney injury (AKI) involves pro-inflammatory responses, apoptosis of renal tubular epithelial cells and vascular damage. AKI increases the risk of chronic kidney disease. Relaxin (RLX) has anti-apoptotic and anti-fibrosis properties. The aim of this study was to investigate the effects of RLX on CDDP-induced nephrotoxicity.

METHODS

We investigated the mitigating effects of RLX based on the etiopathology of AKI induced by CDDP, and also the anti-fibrotic effect of RLX on renal fibrosis after AKI. In the short-term experiments, rats were divided into the control group, CDDP group, and CDDP+RLX group. In the latter group, RLX was infused for 5 or 14 days using an implanted osmotic minipump. CDDP was injected intraperitoneally (6 mg/kg) after RLX or saline infusion. At 5 and 14 days post-CDDP, the kidneys were removed for analysis. The effect of RLX on renal fibrosis after AKI was evaluated at 6 weeks post-CDDP.

RESULTS

In short-term experiments, CDDP transiently increased plasma creatinine and blood urea nitrogen with peaks at day 5, and RLX prevented such rises. Semiquantitative analysis of the histological lesions indicated marked structural damage and apoptotic cells in the CDDP group, with the lesions being reduced by RLX treatment. Overexpression of Bax, interleukin-6 and tumor necrosis factor-α observed in the kidneys of the CDDP group was reduced in the CDDP+RLX group. In the long-term experiments, RLX significantly reduced renal fibrosis compared with the CDDP group.

CONCLUSIONS

The results suggested that RLX provided protection against CDDP-induced AKI and subsequent fibrosis by reducing apoptosis and inflammation.

Recombinant human relaxin-2: (how) can a pregnancy hormone save lives in acute heart failure?

Acute heart failure (AHF) syndrome, characterized by pulmonary and/or venous congestion owing to increased cardiac filling pressures with or without diminished cardiac output, is still associated with high post-discharge mortality and hospitalization rates. Many novel and promising therapeutic approaches, among them endothelin-1, vasopressin and adenosine antagonists, calcium sensitization, and recombinant B-type natriuretic hormone, have failed in large studies. Likewise, the classic drugs, vasodilators, diuretics, and inotropes, have never been shown to lower mortality.The phase III trial RELAX-AHF tested recombinant human relaxin-2 (rhRlx) and found it to improve clinical symptoms moderately, to be neutral regarding the combination of death and hospitalization at day 60, to be safe, and to lower mortality at day 180. This review focuses on basic research and pre-clinical findings that may account for the benefit of rhRlx in AHF. The drug combines short-term hemodynamic advantages, such as moderate blood pressure decline and functional endothelin-1 antagonism, with a wealth of protective effects harboring long-term benefits, such as anti-inflammatory, anti-fibrotic, and anti-oxidative actions. These pleiotropic effects are exerted through a complex and intricate signaling cascade involving the relaxin-family peptide receptor-1, the glucocorticoid receptor, nitric oxide, and a cell type-dependent variety of kinases and transcription factors.

Relaxin does not improve Angiotensin II-induced target-organ damage

Relaxin is a corpus-luteum produced protein hormone with vasodilatatory, anti-fibrotic, and angiogenic properties that are opposite to angiotensin (Ang) II. We investigated whether or not relaxin ameliorates Ang II-induced target-organ damage. We used double transgenic rats harboring both human renin and angiotensinogen genes (dTGR) that develop severe hypertension, target-organ damage, and die untreated within 7–8 weeks. Recombinant relaxin at a low (26 μg/kg/d) and a high dose (240 μg/kg/d) was given to 4 week-old dTGR and age-matched Sprague-Dawley rats (SD). Systolic blood pressure increased progressively in untreated dTGRs from 162±3 mmHg at week 5 to 225±5 mmHg at week 7. Relaxin had no effect on blood pressure whereas SD rats were normotensive (106±1 mmHg). Untreated and relaxin-treated dTGR had similarly severe cardiac hypertrophy indices. Relaxin did not ameliorate albuminuria and did not prevent matrix-protein deposition in the heart and kidney in dTGR. Finally, relaxin treatment did not reduce mortality. These data suggest that pharmacological doses of relaxin do not reverse severe effects of Ang II.

Therapeutic effects of serelaxin in acute heart failure

Over the past few decades, research on the peptide hormone, relaxin, has significantly improved our understanding of its biological actions under physiological and diseased conditions. This has facilitated the conducting of clinical trials to explore the use of serelaxin (human recombinant relaxin). Acute heart failure (AHF) is a very difficult to treat clinical entity, with limited success so far in developing new drugs to combat it. A recent phase-III RELAX-AHF trial using serelaxin therapy given during hospitalization revealed acute (ameliorated dyspnea) and chronic (improved 180-day survival) effects. Although these findings support a substantial improvement by serelaxin therapy over currently available therapies for AHF, they also raise key questions and stimulate new hypotheses. To facilitate the development of serelaxin as a new drug for heart disease, joint efforts of clinicians, research scientists and pharmacological industries are necessary to study these questions and hypotheses. In this review, after providing a brief summary of clinical findings and the pathophysiology of AHF, we present a working hypothesis of the mechanisms responsible for the observed efficacy of serelaxin in AHF patients. The existing clinical and preclinical data supporting our hypotheses are summarized and discussed. The development of serelaxin as a drug provides an excellent example of the bilateral nature of translational research.