The effects of craniocerebral and extracranial trauma on the changes in serum testosterone and estradiol in the early stage and their clinical significance

Sex dimorphisms in coagulation: Implications in trauma-induced coagulopathy and trauma resuscitation

Trauma-induced coagulopathy (TIC) is one of the leading causes of preventable death in injured patients. Consequently, it is imperative to understand the mechanisms underlying TIC and how to mitigate this mortality. An opportunity for advancement stems from the awareness that coagulation demonstrates a strong sex-dependent effect. Females exhibit a relative hypercoagulability compared to males, which persists after injury and confers improved outcomes. The mechanisms underlying sex dimorphisms in coagulation and its protective effect after injury have yet to be elucidated. This review explores sex dimorphisms in enzymatic hemostasis, fibrinogen, platelets, and fibrinolysis, with implications for resuscitation of patients with TIC.

17beta-estradiol alleviates contusion-induced skeletal muscle injury by decreasing oxidative stress via SIRT1/PGC-1α/Nrf2 pathway

PURPOSE

This study aimed to investigate the role of 17β-estradiol (E₂) in the repair of contusion-induced myoinjury in mice and to identify the underlying molecular mechanisms.

METHODS

In vivo, contusion protocol was performed for preparing mice myoinjury model, and Injection (i.p.) of 17β-estradiol (E₂) or estrogen receptor antagonist ICI 182,780, or ovariectomy (OVX), was used to alter estrogen level of animal models. In vitro, C₂C₁₂ myoblasts were treated with H₂O₂ (oxidative stress inducer), SIRT1 inhibitor EX527, or aromatase inhibitor anastrozole. Serum E₂ level was assessed by enzyme-linked immunosorbent assay (ELISA). Muscle damage repair was evaluated by H&E staining and the activities of serum creatine kinase (CK) and lactate dehydrogenase (LDH). The oxidative stress was estimated by the levels of catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA). Western blot was performed to measure the protein expressions of SIRT1, PGC-1α, Nrf2, and HO-1.

RESULTS

We observed the elevated serum E₂ levels and the upregulated oxidative stress in damaged muscle in female mice after contusion-induction. The E₂ administration in vivo alleviated contusion-induced myoinjury in OVX mice by reducing CK and LDH activities, suppressing oxidative stress, and enhancing the expression levels of SIRT1, PGC-1α, Nrf2, and HO-1. These effects were inhibited by treatment with an ERα/β antagonist. Moreover, EX527 or anastrozole treatment exacerbated H₂O₂-induced growth inhibition and oxidative stress, and expression downregulation of SIRT1, PGC-1α, Nrf2, and HO-1 in C₂C₁₂ cells in vitro.

CONCLUSION

Our results suggest that E₂ is a positive intervention factor for muscle repair followed contusion-induced myoinjury, through its effects on suppressing oxidative stress via activating the SIRT1/PGC-1α/Nrf2 pathway.

Estrogen signaling effects on muscle-specific immune responses through controlling the recruitment and function of macrophages and T cells

Background

Estrogen signaling is indispensable for muscle regeneration, yet the role of estrogen in the development of muscle inflammation, especially in the intramuscular T cell response, and the influence on the intrinsic immuno-behaviors of myofibers remain largely unknown. We investigated this issue using the mice model of cardiotoxin (CTX)-induced myoinjury, with or without estrogen level adjustment.

Methods

CTX injection i.m. (tibialis anterior, TA) was performed for preparing mice myoinjury model. Injection s.c. of 17β-estradiol (E₂) or estrogen receptor antagonist 4-OHT, or ovariectomy (OVX), was used to change estrogen level of animal models in vivo. Serum E₂ level was evaluated by ELISA. Gene levels of estrogen receptor (ERs) and cytokines/chemokines in inflamed muscle were monitored by qPCR. Inflammatory infiltration was observed by immunofluorescence. Macrophage and T cell phenotypes were analyzed by FACS. Immunoblotting was used to assess protein levels of ERs and immunomolecules in C₂C₁₂ myotubes treated with E₂ or 4-OHT, in the presence of IFN-γ.

Results

We monitored the increased serum E₂ level and the upregulated ERβ in regenerated myofibres after myotrauma. The absence of estrogen in vivo resulted in the more severe muscle inflammatory infiltration, involving the recruitment of monocyte/macrophage and CD4⁺ T cells, and the heightened proinflammatory (M1) macrophage. Moreover, estrogen signaling loss led to Treg cells infiltration decrease, Th1 response elevation in inflamed muscle, and the markedly expression upregulation of immunomolecules in IFN-γ-stimulated C₂C₁₂ myotubes in vitro.

Conclusion

Our data suggest that estrogen is a positive intervention factor for muscle inflammatory response, through its effects on controlling intramuscular infiltration and phenotypes of monocytes/macrophages, on affecting accumulation and function of Treg cells, and on suppressing Th1 response in inflamed muscle. Our findings also imply an inhibition effect of estrogen on the intrinsic immune behaviors of muscle cells.