Abstract
Although it is now recognized that women suffer from myofascial pain to a greater extent than men, and that the muscular fasciae can respond to hormonal stimuli, thanks to the expression of sex hormone receptors, how the fasciae can modify their structure under hormonal stimulation is not clear. In this work, an immunocytochemical analysis of collagen-I, collagen-III and fibrillin were carried out on fibroblasts isolated from human fascia lata after in vitro treatment with various levels of sex hormones β-estradiol and/or relaxin-1, according to the phases of a woman’s period (follicular, periovulatory, luteal, post-menopausal phases and pregnancy). This study demonstrates for the first time that fascial cells can modulate the production of some components of the extracellular matrix according to hormone levels, when treated with β-estradiol: collagen-I falls from 6% of positivity in the follicular phase to 1.9 in the periovulatory phase. However, after the addition of relaxin-1 to the cell culture, the production of extracellular matrix decreased and remained at the same level (1.7% of collagen-I, at both follicular and periovulatory levels of hormones). These results confirm the antifibrotic function of relaxin-1, thanks to its ability to reduce matrix synthesis. They are also a first step in our understanding of how some hormonal dysfunctions in women can cause a dysregulation of extracellular matrix production in fasciae.
Highlights
Estrogens have long been known as a regulating factor of metabolism in tissues such as bone, muscle, cartilage, tendon and ligament, affecting the musculoskeletal functions [1]
The pictures revealed some modifications according to hormone levels: after treatment with low concentrations of β-estradiol (10 Pregnancy (2nd trimester) β-Estradiol (pg/mL), post-menopausal levels) (Fig 1C), the staining decreased with respect to control cells (Fig 1B), but was much more evident with increasing hormone levels up to 5000 pg/mL (Fig 1F), corresponding to the average amount of β-estradiol during the 2nd trimester of pregnancy
Fascial cells can modulate the production of the extracellular matrix: when treated for 48 h with β-estradiol, the amount of collagen-I, III and fibrillin changed greatly according to hormone levels
Summary
Estrogens have long been known as a regulating factor of metabolism in tissues such as bone, muscle, cartilage, tendon and ligament, affecting the musculoskeletal functions [1]. The estrogen-beta receptor has been described recently in the tissue of tendons and ligaments [2], and only in one of our recent works [3] the expression of sex hormone receptors was demonstrated in the muscular fasciae. It was recently observed that knee laxity is significantly greater around ovulation, when estrogen peaks [4], with an increased risk of injury [5]. Another study has shown that short-term exposure to physiological concentrations of estrogen decreases the mechanical function of ligaments by inhibiting the activity of the crosslinking enzyme lysyl oxidase, which contributes to the increased laxity seen in the female knee [7]
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