Sphingosine 1-phosphate (S1P) receptor agonists mediate pro-fibrotic responses in normal human lung fibroblasts via S1P2 and S1P3 receptors and Smad-independent signaling.

Synthetic sphingosine 1-phosphate receptor 1 modulators constitute a new class of drugs for the treatment of autoimmune diseases. Sphingosine 1-phosphate (S1P) signaling, however, is also involved in the development of fibrosis. Using normal human lung fibroblasts, we investigated the induction of fibrotic responses by the S1P receptor (S1PR) agonists S1P, FTY720-P, ponesimod, and SEW2871 and compared them with the responses induced by the known fibrotic mediator TGF-ß1. In contrast to TGF-ß1, S1PR agonists did not induce expression of the myofibroblast marker α-smooth muscle actin. However, TGF-ß1, S1P, and FTY720-P caused robust stimulation of extracellular matrix (ECM) synthesis and increased pro-fibrotic marker gene expression including connective tissue growth factor. Ponesimod showed limited and SEW2871 showed no pro-fibrotic potential in these readouts. Analysis of pro-fibrotic signaling pathways showed that in contrast to TGF-ß1, S1PR agonists did not activate Smad2/3 signaling but rather activated PI3K/Akt and ERK1/2 signaling to induce ECM synthesis. The strong induction of ECM synthesis by the nonselective agonists S1P and FTY720-P was due to the stimulation of S1P2 and S1P3 receptors, whereas the weaker induction of ECM synthesis at high concentrations of ponesimod was due to a low potency activation of S1P3 receptors. Finally, in normal human lung fibroblast-derived myofibroblasts that were generated by TGF-ß1 pretreatment, S1P and FTY720-P were effective stimulators of ECM synthesis, whereas ponesimod was inactive, because of the down-regulation of S1P3R expression in myofibroblasts. These data demonstrate that S1PR agonists are pro-fibrotic via S1P2R and S1P3R stimulation using Smad-independent pathways.

Identification of cathepsin L as a potential sex-specific biomarker for renal damage.

The renin-angiotensin system is a well-known regulator of blood pressure and plays an important role in the pathogenesis of cardiovascular disease and renal damage. Genetic factors, including single nucleotide polymorphisms and sex, are increasingly recognized as potential risk factors for the development of cardiovascular disease. Double transgenic rats (dTGRs), harboring human renin and angiotensinogen genes, were used in this study to investigate potential sex differences influencing renal function and renal gene expression. dTGR males and females had comparable increases in blood pressure, whereas body weight, albuminuria/proteinuria, and urine flow rate were higher in males. At 8 weeks of age, renal plasma flow and glomerular filtration rate were proportionally lower in males, and renal vascular resistance tended to be higher. Males developed more severe tubulointerstitial and vascular lesions. By the end of week 8, 40%of the males but none of the females had died. Genome expression studies were performed with RNA from kidneys of 7-week-old male and female dTGRs and control rats to further investigate the sex-related differences on a molecular level. Forty-five genes showed sex-dependent expression patterns in dTGRs that were significantly different compared to controls. Cathepsin L, one of the genes differentially expressed between the sexes, was also shown to be strongly associated with the degree of renal injury. In dTGRs, urinary cathepsin L at week 7 was higher in males (nanograms per 24 hours: male, 512±163; female, 132±70). These results reveal a potential new biomarker for the personalized diagnosis and management of chronic kidney disease.

Xenobiotics in the limbic system--affecting brain's network function.

Xenobiotic compounds enter the brain through nutrition, environmentals, and drugs. In order to maintain intrinsic homeostasis, the brain has to adapt to xenobiotic influx. Among others, steroid hormones appear as crucial mediators in this process. However, especially in the therapy of neurological diseases or brain tumors, long-term application of neuroactive drugs is advised. Several clinically important malignancies based on hormonal dysbalance rise up after treatment with neuroactive drugs, for example, sexual and mental disorders or severe cognitive changes. A drug-hormone cross talk proceeding over drug-mediated cytochrome P450 induction predominantly in the limbic system and the blood-brain barrier, consequently altered steroid hormone metabolism, and P450-mediated change of steroid hormone receptor expression and signaling may serve as an explanation for such disorders. Especially, the interplay between the expression of AR and P450 at the blood-brain barrier and in structures of the limbic system is of considerable interest in understanding brain's reaction on xenobiotic treatment. This chapter summarizes present models and concepts on brain's reaction after xenobiotics crossing the blood-brain barrier and invading the limbic system.

Modulation of androgen and estrogen receptor expression by antiepileptic drugs and steroids in hippocampus of patients with temporal lobe epilepsy.

PURPOSE: Many of the antiepileptic drugs (AED) used in therapy of temporal lobe epilepsy (TLE) are known as cytochrome P450 (CYP, P450) inducers. These AEDs are thought to modulate androgen and estrogen pathways in hippocampus, and therefore cause mental and reproductive disorders found in TLE patients. In the present study, we analyzed expression of androgen receptor (AR), estrogen receptor alpha (ERalpha), and CYP3A in the hippocampus of TLE patients and in murine hippocampal cell line HN25.1. METHODS: Patients and cell lines had been treated with P450-inducing or noninducing AEDs, or with prednisolone, applied to prevent oedema formation prior to neurosurgical resection of the epileptic hippocampus. Human patient samples were analyzed by immunohistochemical approach, the HN25.1 cell line by quantitative RT-PCR, CAT reporter gene assay, and immunoblot. RESULTS: In both, humans and cell lines, the expression of testosterone metabolising CYP3A4 (human) or CYP3A11 (mouse) and AR was up-regulated when P450-inducing AEDs and/or prednisolone had been applied. AR responsive CAT reporter gene assay indicated an increase of AR-signalling after treatment of the HN25.1 cells with the P450-inducers phenytoin and carbamazepine. ERalpha expression was increased only by the P450-inducing AEDs, but not by prednisolone, which indicates that pathways different from CYP3A4/11 led to ERalpha enhancement. DISCUSSION: We conclude that P450-inducing AEDs influence AR expression and signalling in hippocampus most likely via CYP3A4/11-induction. The HN25.1 cell line holds promise to investigate the correlation between drug application and AR regulation, and to specifically address issues that are relevant to human TLE patients.