Effects of High Estrogen Levels on Monocyte Chemoattractant Protein-1 and Wound Healing

Low-dose estrogen release from silastic capsule enhanced flap wound healing in an animal model

BACKGROUND

Deep and extensive wounds usually cannot be closed directly by suturing or skin grafting. Flap transplantation is typically used to reconstruct large wounds clinically. The flap survival is based on a stable blood perfusion. It is established that estrogen promotes wound healing and angiogenesis, and regulates the inflammatory response, leading to enhanced flap survival after transplantation. However, estrogen concentrations administered in previous studies were significantly higher than physiological levels, potentially causing systemic side effects. Estrogen-sustained-release silastic capsules can maintain blood serum estrogen closer to physiological levels. This study aimed to investigate whether administering estrogen at a lower concentration, closer to physiological levels, could still enhance flap survival.

MATERIALS AND METHODS

This study was performed in a random skin flap model in ovariectomized (OVX) mice. Sustained-release estrogen silastic capsules were implanted into OVX mice to determine the functional role of estrogen in wound healing after flap transplantation. Flap blood perfusion was analysed using a colour laser Doppler scanner. Immunohistochemical staining of CD31, hypoxia-inducible factor 1 alpha (HIF-1α), alpha-smooth muscle actin (α-SMA), cleaved caspase 3 and apoptotic terminal dUTP nick end-labelling stain was used to investigate flap angiogenesis, tissue hypoxia, wound healing and cell death in the flap tissue, respectively.

RESULTS

We observed that administering estrogen at a lower concentration enhanced superficial blood perfusion while reducing the flap's ischemic area and tissue necrosis. HIF-1α expression was significantly decreased in the dermis layer but not in the fascia, whereas cleaved caspase 3 levels decreased in the fascia but remained unchanged in the dermis. Additionally, there was no significant difference in CD31and α-SMA expression between the groups.

CONCLUSION

In summary, the study showed that an estrogen silastic capsule maintained physiological estrogen levels and improved superficial perfusion, thereby reducing dermal hypoxia, and cell death in a mouse random pattern skin flap model. Although no significant promotion of angiogenesis was observed, the study suggests that appropriate estrogen supplements could enhance flap wound recovery.

The beneficial roles and mechanisms of estrogens in immune health and infection disease

Multiple epidemiologic studies have revealed that gender is considered one of the important factors in the frequency and severity of certain infectious diseases, in which estrogens may play a vital role. There is growing evidence that estrogens as female sex hormone can modulate multiple biological functions outside of the reproductive system, such as in brain and cardiovascular system. However, it is largely unknown about the roles and mechanisms of estrogens/estrogen receptors in immune health and infection disease. Thence, by reading a lot of literature, we summarized the regulatory mechanisms of estrogens/estrogen receptors in immune cells and their roles in certain infectious diseases with gender differences. Therefore, estrogens may have therapeutic potentials to prevent and treat these infectious diseases, which needs further clinical investigation.

Estrogen Receptor Signaling in the Immune System

The immune system functions in a sexually dimorphic manner, with females exhibiting more robust immune responses than males. However, how female sex hormones affect immune function in normal homeostasis and in autoimmunity is poorly understood. In this review, we discuss how estrogens affect innate and adaptive immune cell activity and how dysregulation of estrogen signaling underlies the pathobiology of some autoimmune diseases and cancers. The potential roles of the major circulating estrogens, and each of the 3 estrogen receptors (ERα, ERβ, and G-protein coupled receptor) in the regulation of the activity of different immune cells are considered. This provides the framework for a discussion of the impact of ER modulators (aromatase inhibitors, selective estrogen receptor modulators, and selective estrogen receptor downregulators) on immunity. Synthesis of this information is timely given the considerable interest of late in defining the mechanistic basis of sex-biased responses/outcomes in patients with different cancers treated with immune checkpoint blockade. It will also be instructive with respect to the further development of ER modulators that modulate immunity in a therapeutically useful manner.

Melittin - A bee venom component - Enhances muscle regeneration factors expression in a mouse model of skeletal muscle contusion

Melittin is a major peptide component of sweet bee venom that possesses anti-allergic, anti-inflammatory, anti-arthritis, anti-cancer, and neuroprotective properties. However, the therapeutic effects of melittin on muscle injury have not been elucidated. We investigated the therapeutic effects of melittin on muscle injury in a mouse model of muscle contusion. The biceps femoris muscle of the mice was injured using drop mass method, and the animals were treated with melittin (4, 20, or 100 μg/kg) for 7 days. Melittin significantly increased: locomotor activity in open field test, and treadmill running activity in a dose-dependent manner to level comparable to the positive control, diclofenac (30 mg/kg). Melittin treatment attenuated the pro-inflammatory cytokine MCP-1, TNF-α and IL-6. The expression of muscle regeneration biomarkers, including MyoD (muscle differentiation marker), myogenin, smooth muscle actin, and myosin heavy chain was markedly increased in the injured muscle tissue of melittin-treated mice, as determined by western blotting and quantitative real-time polymerase chain reaction. These results demonstrate that melittin inhibits inflammatory response and improves muscle damage by regenerating muscles in a mouse model of muscle contusion. Taken together, the results of present study suggest that melittin is a promising candidate for the muscle injury treatment.

Estrogen Mitigates the Negative Effects of Arsenic Contamination in an In Vitro Wound Model

Arsenic, a naturally occurring environmental contaminant, is harmful to humans at elevated concentrations. Increased levels of arsenic in the environment occur as a result of human activities and from natural geologically sourced leaching into ground and surface water. These sources pose an exposure risk above the USEPA standard to individuals whose food and water sources become contaminated. Arsenic exposure negatively impacts organ function and increases the risk for developing pathologies, including cancer. Some of the effects of arsenic on cancer translate to normal cell function in wound healing. To evaluate whether arsenic influences wound healing, an in vitro scratch assay was employed to study the effects of arsenic on cellular migration, which is a key component in the normal wound-healing process. In this study, skin cells were exposed to environmentally relevant concentrations of arsenic, and wound closure was evaluated. Results indicated that arsenic significantly decreased the rate of cellular migration in the scratch assay when compared with controls. In addition, estradiol, which has been shown to positively influence cellular and tissue processes involved in wound healing, reversed the slowing effects of arsenic on wound closure. These results suggest that arsenic contamination may inhibit, and estrogen may provide a therapeutic benefit for individuals with arsenic-contaminated wounds.

Letrozole vs estradiol valerate induced PCOS in rats: glycemic, oxidative and inflammatory status assessment

The objective of our study was to investigate glycemic, oxidative/antioxidative and inflammatory status in letrozole and estradiol valerate induced polycystic ovarian syndrome (PCOS) models. Sixty adult female Wistar rats were divided into four groups: L (0.2 mg letrozole/0.5 ml carboxymethyl cellulose (CMC), daily for 30 days), the control group CL, EV (one i.m. injection of 5 mg EV/0.5 ml sesame oil) and its corresponding control group CEV. After 30 days, ovarian morphology was assessed through ultrasound, serum free testosterone was determined, and an oral glucose tolerance test was performed. Blood, muscle, liver and periovarian adipose tissue (POAT) were collected for oxidative/antioxidative and inflammatory status evaluation. Free testosterone was increased only in the L group, while fasting glycemia was higher in the EV group. Both L and EV led to a significantly decreased level of muscle malondialehyde (MDA) and liver glutathione peroxidase (GPx) activity, while in POAT, MDA level diminished and GPx activity increased. The only difference between the two protocols was in muscle, where after L administration, GPx activity was significantly lower. Implementation of both protocols resulted in an increased expression of pNFKB in muscle, liver and POAT. The expression of monocyte chemoattractant protein 1 (MCP1) increased in liver and POAT after L administration, while in the EV group, MCP1 and STAT3 decreased in POAT. Our study shows that both protocols are characterized by an inflammatory environment in the usually insulin resistant tissues of human PCOS, without generating oxidative stress. In addition, EV has mild metabolic effects and unexpected interference with MCP1 expression in POAT, which require further investigation.

Kinetic Profiles of Inflammatory Mediators in the Conjunctival Sac Fluid of Patients upon Photorefractive Keratectomy

Photorefractive keratectomy (PRK) represents a therapeutic option to remodel corneal stroma and to compensate refractive errors, which involves inflammatory and/or regenerative processes. In this context, the modulation of cytokines/chemokines in the conjunctival sac fluid and their role in the maintenance of the corneal microenvironment during the healing process upon refractive procedures has not been deeply investigated. In this study, serial samples of conjunctival sac fluid of patients (n = 25) undergoing PRK were harvested before and at different time points after surgery. The levels of 29 cytokines/chemokines/growth factors involved in inflammatory/immune processes were measured with a multiplex array system. The results have firstly highlighted the different pattern of cytokine expression between the microenvironment at the anterior surface of the eye and the systemic circulation. More importantly, the kinetic of modulation of cytokines/chemokines at the conjunctival level following PRK revealed that while the majority of cytokines/chemokines showed a significant decrease, MCP-1 emerged in light of its pronounced and significant increase soon after PRK and during the follow-up. This methodological approach has highlighted the role of MCP-1 in the healing process following PRK and has shown a potential for the identification of expression/modulation of soluble factors for biomarker profiling in ocular surface diseases.