The pregnancy hormone relaxin binds to and activates the human glucocorticoid receptor

Relaxin suppresses atrial fibrillation, reverses fibrosis and reduces inflammation in aged hearts

Healthy aging results in cardiac structural and electrical remodeling that increase susceptibility to cardiovascular diseases. Relaxin has shown broad cardioprotective effects including anti-fibrotic, anti-arrhythmic and anti-inflammatory outcomes in multiple models. This paper focuses on the cardioprotective effects of Relaxin in a rat model of aging. Sustained atrial or ventricular fibrillation are readily induced in the hearts of aged but not young control animals. Treatment with Relaxin suppressed this arrhythmogenic response by increasing conduction velocity, decreasing fibrosis and promoting substantial cardiac remodeling. Relaxin treatment resulted in a significant increase in the levels of: Nav1.5, Cx43, βcatenin and Wnt1 in rat hearts. In isolated cardiomyocytes, Relaxin increased Nav1.5 expression. These effects were mimicked by CHIR 99021, a pharmacological activator of canonical Wnt signaling, but blocked by the canonical Wnt inhibitor Dickkopf1. Relaxin prevented TGF-β-dependent differentiation of cardiac fibroblasts into myofibroblasts while increasing the expression of Wnt1; the effects of Relaxin on cardiac fibroblast differentiation were blocked by Dickkopf1. RNASeq studies demonstrated reduced expression of pro-inflammatory cytokines and an increase in the expression of α- and β-globin in Relaxin-treated aged males. Relaxin reduces arrhythmogenicity in the hearts of aged rats by reduction of fibrosis and increased conduction velocity. These changes are accompanied by substantial remodeling of the cardiac tissue and appear to be mediated by increased canonical Wnt signaling. Relaxin also exerts significant anti-inflammatory and anti-oxidant effects in the hearts of aged rodents. The mechanisms by which Relaxin increases the expression of Wnt ligands, promotes Wnt signaling and reprograms gene expression remain to be determined.

Effect of dietary chitosan oligosaccharide supplementation on the pig ovary transcriptome

Fecundity improvement is one of the most important economic traits for the swine industry. In this study, we identified 486 differentially expressed genes associated with sow prolificacy from COS administrated sow ovaries by RNA-seq.

Tumor-associated macrophages and stromal TNF-α regulate collagen structure in a breast tumor model as visualized by second harmonic generation

Collagen fibers can be imaged with second harmonic generation (SHG) and are associated with efficient tumor cell locomotion. Preferential locomotion along these fibers correlates with a more aggressively metastatic phenotype, and changes in SHG emission properties accompany changes in metastatic outcome. We therefore attempted to elucidate the cellular and molecular machinery that influences SHG in order to understand how the microstructure of tumor collagen fibers is regulated. By quantifying SHG and immunofluorescence (IF) from tumors grown in mice with and without stromal tumor necrosis factor (TNF)-α and in the presence or absence of tumor-associated macrophages (TAMs), we determined that depletion of TAMs alters tumor collagen fibrillar microstructure as quantified by SHG and IF. Furthermore, we determined that abrogation of TNF-α expression by tumor stromal cells also alters fibrillar microstructure and that subsequent depletion of TAMs has no further effect. In each case, metastatic burden correlated with optical readouts of collagen microstructure. Our results implicate TAMs and stromal TNF-α as regulators of breast tumor collagen microstructure and suggest that this regulation plays a role in tumor metastasis. Furthermore, these results indicate that quantification of SHG represents a useful strategy for evaluating the cells and molecular pathways responsible for manipulating fibrillar collagen in breast tumor models.

The regulation of fibrosis in airway remodeling in asthma

Fibrosis is one of the key pathological features of airway remodeling in asthma. In the normal airway the amount of collagen and other extracellular matrix components is kept in equilibrium by regulation of synthesis and degradation. In asthma this homeostasis is disrupted due to genetic and environmental factors. In the airways of patients with the disease there is increased extracellular matrix deposition, particularly in the reticular basement membrane region, lamina propria and submucosa. Fibrosis is important as it can occur early in the pathogenesis of asthma, be associated with severity and resistant to therapy. In this review we will discuss current knowledge of relaxin and other key regulators of fibrosis in the airway including TGFβ, Smad2/3 and matrix metalloproteinases. As fibrosis is not directly targeted or effectively treated by current asthma drugs including corticosteroids, characterization of airway fibrosis and how it is regulated will be essential for the development of novel therapies for asthma.

Morphological examination of the corpora lutea from pregnant bitches treated with different abortifacient regimes

Different abortifacient regimes in dogs were analysed for their effect on the pregnancy corpora lutea (CL), namely, prostaglandin F2a analogue cloprostenol (CLO) combined with dopamine agonist cabergoline (CAB), or progesterone (P4) receptor antagonist aglepristone (AGL). Ovaries were collected after 6-10 days of treatment during first trimester. The CL of the control-group showed strong expression of relaxin (RLX), its receptor RXFP1 and enzymes of steroid biosynthesis (HSD) with high peripheral P4-levels. Whereas RXL, RXFP1 and HSD were lowest expressed in the CLO/CAB-group with a massive degeneration of CL and their blood vessels combined with low peripheral P4-level. The AGL-group showed less extensive CL degeneration and more intensive staining of the examined factors than CLO/CAB. In summary, all examined factors are associated with normal luteal function and are useful tools to stage luteolysis. Although both treatments have the same abortive action, their sequence of events on the CL is different.

Relaxin signaling activates peroxisome proliferator-activated receptor gamma

Relaxin is a polypeptide hormone that triggers multiple signaling pathways through its receptor RXFP1 (relaxin family peptide receptor 1). Many of relaxin's functions, including vascular and antifibrotic effects, are similar to those induced by activation of PPARgamma. In this study, we tested the hypothesis that relaxin signaling through RXFP1 would activate PPARgamma activity. In cells overexpressing RXFP1 (HEK-RXFP1), relaxin increased transcriptional activity through a PPAR response element (PPRE) in a concentration-dependent manner. In cells lacking RXFP1, relaxin had no effect. Relaxin increased both the baseline activity and the response to the PPARgamma agonists rosiglitazone and 15d-PGJ(2), but not to agonists of PPARalpha or PPARdelta. In HEK-RXFP1 cells infected with adenovirus expressing PPARgamma, relaxin increased transcriptional activity through PPRE, and this effect was blocked with an adenovirus expressing a dominant-negative PPARgamma. Knockdown of PPARgamma using siRNA resulted in a decrease in the response to both relaxin and rosiglitazone. Both relaxin and rosiglitazone increased expression of the PPARgamma target genes CD36 and LXRalpha in HEK-RXFP1 and in THP-1 cells naturally expressing RXFP1. Relaxin did not increase PPARgamma mRNA or protein levels. Treatment of cells with GW9662, an inhibitor of PPARgamma ligand binding, effectively blocked rosiglitazone-induced PPARgamma activation, but had no effect on relaxin activation of PPARgamma. These results suggest that relaxin activates PPARgamma activity, and increases the overall response in the presence of PPARgamma agonists. This activation is dependent on the presence of RXFP1. Furthermore, relaxin activates PPARgamma via a ligand-independent mechanism. These studies represent the first report that relaxin can activate the transcriptional activity of PPARgamma.

Gender and sex hormones in multiple sclerosis pathology and therapy

Several lines of evidence indicate that gender affects the susceptibility and course of multiple sclerosis (MS) with a higher disease prevalence and overall better prognosis in women than men. This sex dimorphism may be explained by sex chromosome effects and effects of sex steroid hormones on the immune system, blood brain barrier or parenchymal central nervous system (CNS) cells. The well known improvement in disease during late pregnancy has also been linked to hormonal changes and has stimulated recent clinical studies to determine the efficacy of and tolerance to sex steroid therapeutic approaches. Both clinical and experimental studies indicate that sex steroid supplementation may be beneficial for MS. This could be related to anti-inflammatory actions on the immune system or CNS and to direct neuroprotective properties. Here, clinical and experimental data are reviewed with respect to the effects of sex hormones or gender in the pathology or therapy of MS or its rodent disease models. The different cellular targets as well as some molecular mechanisms likely involved are discussed.

Relaxin—a pleiotropic hormone and its emerging role for experimental and clinical therapeutics

The insulin-related peptide hormone relaxin (Rlx) is known as pregnancy hormone for decades. In the 1980s, researchers began to recognize the highly intriguing fact that Rlx plays a role in a multitude of physiological processes far beyond pregnancy and reproduction. So, Rlx's contribution to the regulation of vasotonus, plasma osmolality, angiogenesis, collagen turnover, and renal function has been established. In addition, the peptide has been demonstrated to represent a mediator of cardiovascular pathology. The ongoing efforts to identify Rlx receptors eventually precipitated the discovery of the G protein-coupled receptors (GPCR) LGR7 and LGR8 as membrane receptors for human Rlx-2 in 2002. This review will summarize the current state of insight into this rapidly evolving field, which has further been expanded by the discovery of GPCR135 and GPCR142 as receptors for Rlx-3. In addition, Rlx has also been shown to activate the human glucocorticoid receptor (GR). There is evidence from Rlx and Rlx receptor knockouts suggesting that LGR7 is the only relevant receptor for mouse Rlx-1 (corresponding to human Rlx-2) in vivo and that insulin-like peptide (INSL)-3 represents the physiological ligand for LGR8. Regarding Rlx signal transduction, the cyclic adenosine monophosphate (cAMP) and nitric oxide (NO) pathways will be characterized as major cascades. Investigation of downstream signaling remains an important field for future research. Finally, the current state of therapeutical strategies using Rlx in animal models as well as in humans is summarized.

Relaxin prevents the development of severe acute pancreatitis

AIM: To investigate the severity of acute pancreatitis (AP) is associated to the intensity of leukocyte activation, inflammatory up-regulation and microcirculatory disruption associated to ischemia-reperfusion injury. Microvascular integrity and inhibition of pro-inflammatory mediators are key-factors in the evolution of AP. Relaxin is an insulin-like hormone that has been attributed vasorelaxant properties via the nitric oxide pathway while behaving as a glucocorticoid receptor agonist.

METHODS: AP was induced by the bilio-pancreatic duct-outlet-exclusion closed-duodenal-loops model. Treatment with relaxin was done at different time-points. Nitric oxide synthase inhibition by L-NAME and glucocorticoid receptor (GR) blockage by mifepristone was considered. AP severity was assessed by biochemical and histopathological analyses.

RESULTS: Treatment with relaxin reduced serum amylase, lipase, C-reactive protein, IL-6, IL-10, hsp72, LDH and 8-isoprostane as well as pancreatic and lung myeloperoxidase. Acinar and fat necrosis, hemorrhage and neutrophil infiltrate were also decreased. ATP depletion and ADP/ATP ratio were reduced while caspases 2-3-8 and 9 activities were increased. L-NAME and mifepristone decreased the efficiency of relaxin.

CONCLUSION: Relaxin resulted beneficial in the treatment of AP combining the properties of a GR agonist while preserving the microcirculation and favoring apoptosis over necrosis.