A Novel Role for Relaxin-2 in the Pathogenesis of Primary Varicosis

Abstract

BackgroundVaricose veins affect up to 40% of men and up to 51% of women. The pathophysiology of primary varicosis is poorly understood. Theories ranging from incompetence of the venous valves to structural changes in the vein wall have been proposed.Methodology/Principal FindingsWe analyzed the functional state of the intramural smooth muscle cells (n = 14 pairs matched for age and gender) and the expression of relaxin-2 and its receptors RXFP1 and RXFP2 in samples of varicose and healthy great saphenous veins (GSV) (n = 21 healthy GSV; n = 46 varicose GSV). Relaxin-2 and RXFP1 contents were determined in tissue samples (n = 9 samples per group). Pharmacological analyses were performed in a perfusion chamber. Morphometric determination of the nuclear size of the smooth muscle compartment yielded no significant difference in varicose GSV in comparison with the healthy controls. Relaxin-2 and its receptors were expressed in the muscular layer, endothelial cells and in blood vessels contained in the vein wall. Immunohistochemical expression of relaxin-2, RXFP1 and RXFP2 was significantly decreased in varicose GSV. Relaxin-2 and RXFP1 measured by ELISA and Western Blot were decreased in varicose GSV (relaxin-2 ELISA healthy vs. varicose GSV: 12.49±0.66 pg/mg versus 9.12±3.39 pg/mg of total protein; p = 0.01; Student's T-test). Contractions of vein samples induced by cholinergic or adrenergic stimulation were antagonized by relaxin-2.Conclusions/SignificanceWe report that relaxin-2 and its receptors RXFP1 and RXFP2 are expressed in GSV and that their expression is significantly decreased in varicose GSV. Further, we were able to demonstrate a functional pharmacological relaxin-2 system in varicose GSV. Our results suggest a novel role for relaxin-2 in the pathogenesis of primary varicosis, rendering relaxin-2 a novel possible pharmacological agent for the treatment of this widely prevailing venous disease.

Endocrine mechanisms in the pathogenesis of primary varicosis

“…A possible involvement of estrogen and progesterone in varicosis was proposed by Mashiah and colleagues (27), who detected a gender-specific expression of the two sex hormones in healthy and varicose GSV. More recently, our group was able to show an altered expression of the hormones relaxin-2 and oxytocin and their respective receptors in healthy and varicose GSV (1,37). Here, an overview of available data on endocrine mechanisms in the (varicose) GSV is summarized.…”

“…Our group recently analyzed the expression of relaxin-2 and its receptors RXFP1 and RXFP2 in samples of 21 healthy and 46 varicose GSV by immunohistochemistry (1). In healthy and varicose GSV, relaxin-2 and its receptors were strongly expressed in endothelial cells, in smooth muscle cells of the tunica media, and in vasa vasorum of the adventitia.…”

Presence of relaxin‐2, oxytocin and their receptors in uterosacral ligaments of pre‐menopausal patients with and without pelvic organ prolapse

“…The primary antibodies used in this study were anti‐human relaxin‐2 (1:300; rabbit, polyclonal, Immundiagnostik AG, Bensheim, Germany), anti‐relaxin receptor 1 (anti‐RXFP1, 1:50; rabbit, polyclonal, GenWay, San Diego, CA, USA), anti‐relaxin receptor 2 (anti‐RXFP2, 1:50; rabbit, polyclonal, Genway), anti‐human oxytocin (1:2000; rabbit polyclonal, ab2078, Abcam, Cambridge, UK), and anti‐oxytocin receptor (anti‐OTR, 1:100; rabbit polyclonal, ab13051, Abcam). Immunostaining was carried out using standard protocols as described in our previous publications . Negative control sections were produced by omission of the primary antibody and did not show any staining (data not shown); the positive control slides (human endometrium and myometrium) were stained with the primary antibody, and there was no background reaction.…”

“…Negative control sections were produced by omission of the primary antibody and did not show any staining (data not shown); the positive control slides (human endometrium and myometrium) were stained with the primary antibody, and there was no background reaction. The positive staining controls for the antibodies used in this study were analogous to our previous publications and were generated during the same automatic staining process at the Department of Pathology, Tübingen, Germany. For immunohistochemical analyses, sections of samples of the 23 healthy (non‐POP) and 20 incompetent (POP) uterosacral ligaments were used; however, one sample each of the RXFP2, RXFP1 and OTR slides was lost during the staining process.…”

“…blinded to the clinical diagnosis. A semi‐quantitative staining four‐step score was established [(− no); (+ low); (++ moderate); (+++ strong) presence ] and all slides were classified accordingly with respect to the cytoplasmic presence. For statistical analysis, two groups of samples were clustered: − (no) and + (low) vs. ++ (moderate) and +++ (strong).…”