The effects of recombinant klotho in cisplatin-induced ovarian failure in mice

Ovarian microenvironment: challenges and opportunities in protecting against chemotherapy-associated ovarian damage

BACKGROUND

Chemotherapy-associated ovarian damage (CAOD) is one of the most feared short- and long-term side effects of anticancer treatment in premenopausal women. Accumulating detailed data show that different chemotherapy regimens can lead to disturbance of ovarian hormone levels, reduced or lost fertility, and an increased risk of early menopause. Previous studies have often focused on the direct effects of chemotherapeutic drugs on ovarian follicles, such as direct DNA damage-mediated apoptotic death and primordial follicle burnout. Emerging evidence has revealed an imbalance in the ovarian microenvironment during chemotherapy. The ovarian microenvironment provides nutritional support and transportation of signals that stimulate the growth and development of follicles, ovulation, and corpus luteum formation. The close interaction between the ovarian microenvironment and follicles can determine ovarian function. Therefore, designing novel and precise strategies to manipulate the ovarian microenvironment may be a new strategy to protect ovarian function during chemotherapy.

OBJECTIVE AND RATIONALE

This review details the changes that occur in the ovarian microenvironment during chemotherapy and emphasizes the importance of developing new therapeutics that protect ovarian function by targeting the ovarian microenvironment during chemotherapy.

SEARCH METHODS

A comprehensive review of the literature was performed by searching PubMed up to April 2024. Search terms included 'ovarian microenvironment' (ovarian extracellular matrix, ovarian stromal cells, ovarian interstitial, ovarian blood vessels, ovarian lymphatic vessels, ovarian macrophages, ovarian lymphocytes, ovarian immune cytokines, ovarian oxidative stress, ovarian reactive oxygen species, ovarian senescence cells, ovarian senescence-associated secretory phenotypes, ovarian oogonial stem cells, ovarian stem cells), terms related to ovarian function (reproductive health, fertility, infertility, fecundity, ovarian reserve, ovarian function, menopause, decreased ovarian reserve, premature ovarian insufficiency/failure), and terms related to chemotherapy (cyclophosphamide, lfosfamide, chlormethine, chlorambucil, busulfan, melphalan, procarbazine, cisplatin, doxorubicin, carboplatin, taxane, paclitaxel, docetaxel, 5-fluorouraci, vincristine, methotrexate, dactinomycin, bleomycin, mercaptopurine).

OUTCOMES

The ovarian microenvironment shows great changes during chemotherapy, inducing extracellular matrix deposition and stromal fibrosis, angiogenesis disorders, immune microenvironment disturbance, oxidative stress imbalances, ovarian stem cell exhaustion, and cell senescence, thereby lowering the quantity and quality of ovarian follicles. Several methods targeting the ovarian microenvironment have been adopted to prevent and treat CAOD, such as stem cell therapy and the use of free radical scavengers, senolytherapies, immunomodulators, and proangiogenic factors.

WIDER IMPLICATIONS

Ovarian function is determined by its 'seeds' (follicles) and 'soil' (ovarian microenvironment). The ovarian microenvironment has been reported to play a vital role in CAOD and targeting the ovarian microenvironment may present potential therapeutic approaches for CAOD. However, the relation between the ovarian microenvironment, its regulatory networks, and CAOD needs to be further studied. A better understanding of these issues could be helpful in explaining the pathogenesis of CAOD and creating innovative strategies for counteracting the effects exerted on ovarian function. Our aim is that this narrative review of CAOD will stimulate more research in this important field.

REGISTRATION NUMBER

Not applicable.

Icariin alleviates cisplatin-induced premature ovarian failure by inhibiting ferroptosis through activation of the Nrf2/ARE pathway

Cisplatin is a widely used chemotherapeutic drug that can induce ovarian damage. Icariin (ICA), a natural antioxidant derived from Epimedium brevicornum Maxim., has been found to protect against organ injury. The aim of the present study was to investigate whether ICA can exert an ovarian-protective effect on cisplatin induced premature ovarian failure (POF) and the underlying mechanism involved. The preventive effect of ICA was evaluated using body weight, the oestrous cycle, ovarian histological analysis, and follicle counting. ICA treatment increased body weight, ovarian weight, and the number of follicles and improved the oestrous cycle in POF mice. ICA reduced cisplatin-induced oxidative damage and upregulated the protein expression levels of Nrf2, GPX4 and HO-1. Moreover, ICA reduced the expression levels of Bax and γH2AX and inhibited ovarian apoptosis. In addition, ICA activated the Nrf2 pathway in vitro and reversed changes in the viability of cisplatin-induced KGN cells, reactive oxygen species (ROS) levels, lipid peroxidation, and apoptosis, and these effects were abrogated when Nrf2 was knocked down or inhibited. Molecular docking confirmed that ICA promotes the release of Nrf2 by competing with Nrf2 for binding to Keap1. The inhibitory effects of ICA on cisplatin-induced oxidative stress, ferroptosis, and apoptosis may be mediated by its modulatory effects on the Nrf2 pathway, providing a novel perspective on the potential mechanisms by which ICA prevents POF.

Understanding the Mechanisms of Diminished Ovarian Reserve: Insights from Genetic Variants and Regulatory Factors

Delaying childbearing age has become a trend in modern times, but it has also led to a common challenge in clinical reproductive medicine-diminished ovarian reserve (DOR). Since the mechanism behind DOR is unknown and its clinical features are complex, physicians find it difficult to provide targeted treatment. Many factors affect ovarian reserve function, and existing studies have shown that genetic variants, upstream regulatory genes, and changes in protein expression levels are present in populations with reduced ovarian reserve function. However, existing therapeutic regimens often do not target the genetic profile for more individualized treatment. In this paper, we review the types of genetic variants, mutations, altered expression levels of microRNAs, and other related factors and their effects on the regulation of follicular development, as well as altered DNA methylation. We hope this review will have significant implications for the future treatment of individuals with reduced ovarian reserve.

Syringic acid alleviates cisplatin-induced ovarian injury through modulating endoplasmic reticulum stress, inflammation and Nrf2 pathway

BACKGROUND

Reproductive toxicity is one of the most important side effects of cisplatin (CIS) and leading to discontinuation of treatment. Syringic acid (SA) is a phenolic acid whose industrial use has increased in recent years due to its antioxidant properties. Recent reports highlight the importance of the supressed Nrf2 pathway in the molecular pathogenesis of CIS toxicity. Therefore, this study aimed to evaluate the therapeutic effect of SA on CIS-induced ovotoxicity through the Nrf2 pathway for the first time.

MATERIAL AND METHODS

Thirty female rats were divided into 5 groups: control, CIS, CIS+SA (5 and 10 mg/kg) and only SA (per se, 10 mg/kg). CIS was administered intraperitoneally at a dose of 5 mg/kg on the 1st day, injections of SA followed by three consecutive days in the rats. Serum anti-mullerian hormone (AMH) levels and ovarian oxidative stress (OS), inflammation, endoplasmic reticulum stress (ERS), apoptosis and Nrf2 pathway markers were determined colorimetrically. Histopathological examinations of the ovaries with hematoxylin and eosin staining were also used to evaluate CIS-induced ovotoxicity.

RESULTS

The CIS treatment depleted serum AMH levels, caused histopathological findings and increased OS, inflammation, ERS and apoptosis levels in ovarian tissue. However, treatments with SA significantly ameliorated CIS-induced biochemical and histopathological changes by activating Nrf2 pathway.

CONCLUSION

The promising adjuvant potential of SA to alleviate CIS-related ovarian damage should be supported by more comprehensive studies.

Paeoniflorin Alleviates Cisplatin-Induced Diminished Ovarian Reserve by Restoring the Function of Ovarian Granulosa Cells via Activating FSHR/cAMP/PKA/CREB Signaling Pathway

Paeoniflorin (PAE) is the main active compound of Radix Paeoniae Rubra (a valuable traditional Chinese medicine and a dietary supplement) and exerts beneficial effects on female reproductive function. However, the actions of PAE on diminished ovarian reserve (DOR, a very common ovarian function disorder) are still unclear. Herein, our study investigated the effect and potential mechanism of PAE on DOR by using cisplatin-induced DOR mice and functional impairment of estradiol (E2) synthesis of ovarian granulosa-like KGN cells. Our data show that PAE improved the estrous cycle, ovarian index, and serum hormones levels, including E2, and the number of antral follicles and corpora lutea in DOR mice. Further mechanism results reveal that PAE promoted aromatase expression (the key rate-limiting enzyme for E2 synthesis) and upregulated the FSHR/cAMP/PKA/CREB signaling pathway in the ovaries. Subsequently, PAE improved the levels of E2 and aromatase and activated the FSHR/cAMP/PKA/CREB signaling pathway in KGN cells, while these improving actions were inhibited by the siRNA-FSHR and FSHR antagonist treatments. In sum, PAE restored the function of E2 synthesis in ovarian granulosa cells to improve DOR by activating the FSHR/cAMP/PKA/CREB signaling pathway, which exhibited a new clue for the development of effective therapeutic agents for the treatment of DOR.

MiR-497-3p induces Premature ovarian failure by targeting KLF4 to inactivate Klotho/PI3K/AKT/mTOR signaling pathway

BACKGROUND

Premature ovarian failure (POF), as a gynecological endocrine disease, features the manifestation of irregular menstruation, amenorrhea, infertility and perimenopausal syndrome. MicroRNAs (miRNAs) have been reported to modulate POF. However, the specific regulatory mechanism of miR-497-3p in POF remain unclear.

METHODS

Quantitative reverse transcription-PCR (RT-qPCR) and western blot were implemented to analyze RNA and protein levels, respectively. Comet assay was performed for the detection of DNA damage. Flow cytometry analysis and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were performed to measure apoptosis of CTX-induced KGN cell (POF cell model). Bioinformatics was utilized to screen out the downstream mRNAs potentially regulated by miR-497-3p. Chromatin immunoprecipitation (ChIP) assay, luciferase reporter assay and RNA pulldown assays were performed to demonstrate the interaction between miR-497-3p and Kruppel-like factor 4 (KLF4) or between KLF4 and Klotho (KL). Rescue assays were performed to verify the involvement of Klotho in miR-497-3p-mediated functions of POF cell model.

RESULTS

MiR-497-3p was upregulated in CTX-treated KGN cells. Knockdown of miR-497-3p could reverse the promoting effects of CTX on DNA damage and cell apoptosis. MiR-497-3p negatively regulated Klotho expression by directly targeting the transcription activator KLF4. KLF4 activated Klotho transcription. MiR-497-3p inactivated PI3K/AKT/mTOR signaling pathway through KLF4/Klotho axis. Klotho knockdown reversed the effects of MiR-497-3p on the functions of POF cell model.

CONCLUSION

MiR-497-3p promotes DNA damage and apoptosis in CTX-treated KGN cells by targeting KLF4 to downregulate Klotho and inactivate the PI3K/AKT/mTOR signaling pathway. This study unveils novel mechanisms associated with cell functional changes in POF and may enrich therapeutic strategy for POF.

Associations between the concentrations of α-klotho and selected perfluoroalkyl substances in the presence of eGFR based kidney function and albuminuria: Data for US adults aged 40-79 years

Exposures to per- and polyfluoroalkyl substances (PFAS) cause oxidative stress, a risk factor for tissue damage leading to kidney and cardiovascular diseases. The antiaging protein klotho is known to act as an anti-oxidative agent, and how klotho homeostasis interacts with PFAS has not been reported. This study among 3981 US adults aged 40-79 years old evaluated relationships of internal PFAS contamination to α-klotho across stages of estimated glomerular filtration rate or eGFR-based kidney function and albuminuria defined as urinary albumin creatinine ratio of >30 mg/g creatinine. In the absence of albuminuria and when eGFR based kidney function was in stage GF-1 (eGFR ≥ 90 mL/min/1.73 m²), statistically significant inverse associations between α-klotho and PFNA (β = -0.04930, p < 0.01), PFDA (β = -0.03307, p = 0.02), and PFUnDA (β = -0.03451, p = 0.01), PFHxS (β = -0.03011, p = 0.04) and PFOS (β = -0.03126, p = 0.03) were noted. No associations between α-klotho and PFAS were observed when kidney function was in stages GF-2 (60 ≤ eGFR < 90 mL/min/1.73 m²) or GF-3A (45 ≤ eGFR < 60 mL/min/1.73 m²) in the presence or absence of albuminuria. Unexpectedly, however, in the absence of albuminuria, with kidney function in stage GF-3B/4 (15 ≤ eGFR < 45 mL/min/1.73 m²), associations were positive between α-klotho and PFOA (β = 0.20989, p < 0.01), PFNA (β = 0.18373, p < 0.1), PFDA (β = 0.20413, p < 0.01), PFUnDA (β = 0.17660, p < 0.01), and PFOS (β = 0.14267, p < 0.01). The inverse relationship of PFAS to the antioxidant protein α-klotho in those with healthy kidney function has not been previously reported and should be evaluated in other populations.

Serum klotho and its associations with blood and urine cadmium and lead across various stages of glomerular function: data for US adults aged 40-79 years

Exposures to cadmium and lead can cause oxidative stress, leading to tissue damage resulting in kidney and cardiovascular diseases. The antiaging protein klotho, on the other hand, is known to act as an anti-oxidative agent. How klotho homeostasis interacts with exposure to cadmium and lead has not been reported. Thus, this study was carried to investigate associations of serum klotho with blood and urine cadmium and lead in US adults aged 40-79 years across stages of eGFR-based kidney function and albuminuria defined as urinary albumin/creatinine ratio of > 30 mg/g creatinine. As long as the kidney function was normal (eGFR ≥ 90 mL/min/1.73 m²) or near normal (60 ≤ eGFR < 90 mL/min/1.73 m²), there was no evidence of an association between cadmium exposure and klotho concentrations irrespective of the presence/absence of albuminuria. During kidney dysfunction (15 ≤ eGFR < 60 mL/min/1.73 m²), 10% increases in blood cadmium concentrations resulted in decreases in klotho concentrations between 0.27 and 0.84%. In addition, during severe kidney dysfunction (15 ≤ eGFR < 45 mL/min/1.73 m²), a positive association between urine cadmium and serum klotho concentrations was observed. In the absence of albuminuria and when kidney function was normal or near normal, 10% increases in blood lead concentrations were observed to be associated with modest decreases between 0.28% and 0.37% in serum klotho concentrations. Similar results were observed between the concentrations of urine lead and serum klotho during kidney dysfunction.