Di-n-butyl phthalate induced autophagy of uroepithelial cells via inhibition of hedgehog signaling in newborn male hypospadias rats

The potential mechanisms underlying phthalate-induced hypospadias: a systematic review of rodent model studies

Objectives

Maternal exposure to environmental endocrine disruptors, such as phthalates, during pregnancy is a significant risk factor for the development of hypospadias. By consolidating existing research on the mechanisms by which phthalates induce hypospadias in rodent models, this systematic review aims to organize and analyze the discovered mechanisms and their potential connections.

Methods

The study involved all articles that explored the mechanisms of phthalate-induced hypospadias using rodent models. A comprehensive search of the PubMed and Web of Science databases was conducted using the terms "hypospadias" and "phthalates" before January 20, 2024. Then, two investigators screened for studies worthy of inclusion by setting inclusion and exclusion criteria.

Results

Of the initial 326 search results, 22 were included in the subsequent analysis. Based on the commonalities among different results, the mechanisms of phthalate-induced hypospadias could be categorized into the following five groups: sex steroids-related signaling pathways (n=10), epithelial-mesenchymal transition (n=6), autophagy (n=5), apoptosis (n=4) and angiogenesis (n=2). Among these, sex steroids-related signaling pathways might serve as a central regulator among all mechanisms, and reactive oxygen species (ROS) also played an important mediating role.

Conclusion

The systematic review indicates that phthalates may initially disrupt the balance of sex steroids-related pathways, leading to abnormally elevated levels of ROS and subsequently to other functional abnormalities, ultimately resulting in the development of hypospadias. All these findings will help to improve prevention strategies during pregnancy to reduce the adverse effects of phthalates on the offspring.

Prenatal exposure to di-n-butyl phthalate promotes RIPK1-regulated necroptosis of uroepithelial cells and induces hypospadias through the epithelial-mesenchymal transition process in newborn male rats

Maternal exposure to di-n-butyl phthalate (DBP) has been linked to the induction of hypospadias; however, the underlying mechanism remains unclear. Necroptosis is reported to be implicated in developmental malformations. This study aimed to investigate the underlying mechanism of necroptosis in the development of hypospadias. DBP was dissolved in corn oil, and pregnant rats were administered a precisely measured dose of DBP (750 mg/kg/day) via gastric intubation from gestation day 14-18. Control rats received only corn oil. The day of birth was considered postnatal day (PND) 1. Male hypospadias rats were identified on PND 7. Genital tubercle tissues were collected and stored at -80°C for subsequent PCR analysis, cryopreserved in liquid nitrogen for western blot, or fixed in formalin for immunohistochemistry (IHC) staining. IHC staining and western blot analysis revealed increased expression of RIPK1 and necroptosis markers in genital tubercle (GT) tissue compared to the control group. Additionally, higher levels of EMT and impaired androgen receptor expression were observed in GT tissue. Exposure to increased DBP concentrations in rat primary uroepithelial cells (PUCs) led to elevated ROS production. Necroptosis markers and EMT expression levels were upregulated in PUCs following DBP incubation. Notably, treatment with DBP combined with necrostatin-1, a necroptosis inhibitor, reduced the expression of EMT markers and ROS production compared to DBP treatment alone. In vitro studies further revealed that DBP-induced necroptosis promoted the degradation of E-cadherin through the ubiquitin-proteasome pathway in PUCs. Our findings suggest that maternal exposure to DBP promotes necroptosis in uroepithelial cells by elevating ROS level and EMT status. Thus, necroptosis may play an essential role in the development of hypospadias.

Maternal exposure to Di-n-butyl phthalate (DBP) inhibit orexin receptor 1 (OX1R) expression to prevent Sertoli cells proliferation through the AKT signaling pathway

BACKGROUND

Studies have demonstrated that Sertoli cells are the direct target of Dibutyl phthalate (DBP). However, the role of neurotransmitter receptors is not elucidated.

METHODS

Based on our previous studies, maternal Sprague-Dawley (SD) rats in Gestation Day (GD) 14-18 and TM4 cells exposure to 750 mg/kg/day and 100 μM DBP were regarded as treated groups. Firstly, qRT-PCR array was used to determine the different expression of neurotransmitter receptors. We examined the OX1R expression on Rats in Control and DBP groups by immunohistochemistry. Real-time PCR and Western Blot were used to detect the protein and mRNA expression levels of OX1R in vivo and in vitro. The potential downstream signaling pathways were explored by analyzing the GSE99690 cohort. In addition, we extracted Primary Sertoli Cells (PSCs) from the testis of control group. The apoptosis-related proteins, AKT signaling pathway-related proteins and mRNA expressions were detected by Western Blot and Real-time PCR in PSCs. The validity of PSCs was measured by CCK-8 assay and flow cytometric analysis was used to demonstrate the apoptotic rates of PSCs after DBP exposure.

RESULTS

The Orexin receptor 1 (OX1R) was screened out by qRT-PCR array. Our results showed that DBP could significantly suppress the OX1R expression of Sertoli cells in vivo and in vitro. Functional analysis showed the AKT signaling pathway was mediated by OX1R. The highly expressed apoptosis level and impaired cell activity were observed in PSCs, which can be reversed by Orexin A. Meanwhile, the p-AKT signaling pathway were hindered after DBP exposure while rescued in DBP + Orexin-A group.

CONCLUSIONS

DBP can induce Sertoli cell apoptosis through its toxicological effect by suppressing OX1R and p-AKT expression, which provide a novel insight on the role of neurotransmitter receptors.

Retrospective studies and quantitative proteomics reveal that abnormal expression of blood pressure, blood lipids, and coagulation related proteins is associated with hypospadias

Hypospadias refers to the abnormal position of the male urethral orifice, which not only leads to urination disorder but also causes sexual dysfunction in adulthood. However, the complex and diverse pathogenic factors of hypospadias are still unclear. To study the pathogenesis and prognosis of hypospadias, we counted the serological indexes of children with hypospadias, and found that sSBP, TC and LDL increased in children with mild, moderate and severe hypospadias. Subsequently, we used quantitative proteomics to find differential proteins in mild, moderate and severe hypospadias. After bioinformatics analysis and biochemical experiments on the screened DEPs, we found that the expression of proteins related to immune inflammation, coagulation, blood pressure and inflammation, and blood lipid were differential expressed in the prepuce tissue of children with hypospadias. We further confirmed that the proteins FGB, FGG, SERPINA1, and AGT involved in the angiotensin system, cholesterol metabolism, and coagulation were significantly up-regulated by biochemical experiments. In particular, the AGT protein of the angiotensin system involved in blood pressure regulation, we have shown that it increases with the severity of hypospadias. This study suggests that children with hypospadias are more likely to suffer from hyperlipidemia and cardiovascular disease (CVD). Our findings provide a theoretical basis for early monitoring of blood lipids and blood pressure to prevent CVD in children with hypospadias.

Urine-derived exosomes and their role in modulating uroepithelial cells to prevent hypospadias

PURPOSE

Urethral hypospadias, a common congenital malformation in males, is closely linked with disruptions in uroepithelial cell (UEC) processes. Evidence exists reporting that urine-derived exosomes (Urine-Exos) enhance UEC proliferation and regeneration, suggesting a potential role in preventing hypospadias. However, the specific influence of Urine-Exos on urethral hypospadias and the molecular mechanisms involved are not fully understood. This study focuses on investigating the capability of Urine-Exos to mitigate urethral hypospadias and aims to uncover the underlying molecular mechanisms.

METHODS

Bioinformatics analysis was performed to identify key gene targets in Urine-Exos potentially involved in hypospadias. Subsequent in vitro and in vivo experiments were conducted to validate the regulatory effects of Urine-Exos on hypospadias.

RESULTS

Bioinformatics screening revealed syndecan-1 (SDC1) as a potential pivotal gene for the prevention of hypospadias. In vitro experiments demonstrated that Urine-Exos enhanced the proliferation and migration of UECs by transferring SDC1 and inhibiting cell apoptosis. Notably, Urine-Exos upregulated β-catenin expression through SDC1 transfer, further promoting UEC proliferation and migration. These findings were confirmed in a congenital hypospadias rat model induced by di(2-ethylhexyl) phthalate (DEHP).

CONCLUSION

This study reveals the therapeutic potential of Urine-Exos in hypospadias, mediated by the SDC1/β-catenin axis. Urine-Exos promote UEC proliferation and migration, thereby inhibiting the progression of hypospadias. These findings offer new insights and potential therapeutic targets for the management of congenital malformations.

Inhibition of Hedgehog signaling ameliorates foam cell formation by promoting autophagy in early atherosclerosis

Macrophages are the origin of most foam cells in the early stage of atherosclerotic plaques. However, the mechanism involved in the formation of macrophage-derived foam cell formation remains unclear. Here, we revealed that the hedgehog (Hh) signaling is critical in autophagy-lysosome pathway regulation and macrophage-derived foam cell formation. Inhibition of Hh signaling by vismodegib ameliorated lipid deposition and oxidative stress level in atherosclerotic plaques in high-fat diet-fed apoE-/- mice. For mechanistic study, how the Hh signaling modulate the process of foam cell formation were accessed afterward. Unexpectedly, we found that suppression of Hh signaling in apoE-/- mice had no significant impact on circulating cholesterol levels, indicating that Hh pathway modulate the procession of atherosclerotic plaque not through a traditional lipid-lowing mechanism. Instead, vismodegib was found to accelerate autophagosomes maturation as well as cholesterol efflux in macrophage-derived foam cell and in turn improve foam cell formation, while autophagy inhibitors (LY294002 or CQ) administration significantly attenuated vismodegib-induced cholesterol efflux and reversed the effect on foam cell formation. Therefore, our result demonstrated that inhibition of the Hh signaling pathway increases cholesterol efflux and ameliorates macrophage-derived foam cell formation by promoting autophagy in vitro. Our data thus suggested a novel therapeutic target of atherosclerosis and indicated the potential of vismodegib to treat atherosclerosis.

Di-isononyl phthalate induces apoptosis and autophagy of mouse ovarian granulosa cells via oxidative stress

Di-isononyl phthalate (DINP) has been widely utilized in industrial, commercial and medical applications for the past few years. Therefore, more attention should be paid to the toxicity of DINP. DINP can cause damage to female reproductive system; however, the potential mechanism remains to be further investigated. In this study, female mice were orally administered with 0, 2, 20 and 200 mg DINP/kg/day for 14 days. We found that DINP significantly affected the arrangement of granulosa cells in ovarian follicles. In addition, DINP could induce apoptosis, autophagy and oxidative stress of the ovary tissue. Meanwhile, the serum estradiol concentration distinctly decreased in the 20 and 200 mg/kg DINP-treated groups, suggesting that DINP might affect the function of ovarian granulosa cells. Primary mouse ovarian granulosa cells were utilized for further investigation after the cells were treated with 0, 100, 200, 400 μM DINP for 24 h. Similar to the in vivo experiment, DINP could also induce apoptosis and autophagy of ovarian granulosa cells, as well as oxidative stress; while inhibition of oxidative stress by NAC could alleviate DINP-induced apoptosis and autophagy. Furthermore, inhibition of autophagy by 3-MA could also rescue the induction of apoptosis by DINP. Taken together, these results indicated that DINP induced apoptosis and autophagy of mouse ovarian granulosa cells via oxidative stress, and autophagy played a cytotoxic role in DINP-induced apoptosis.

The aggravation of allergic airway inflammation with dibutyl phthalate involved in Nrf2-mediated activation of the mast cells

Dibutyl phthalate (DBP)-an organic pollutant-is ubiquitous in the environment. DBP as an immune adjuvant is related to the development of multiple allergic diseases. However, the current research involving DBP-induced pulmonary toxicity remains poorly understood. Therefore, this research aimed to explore the adverse effect and potential mechanism of DBP exposure on the lungs in rats. In our study, ovalbumin was used to build a rat model of allergic airway inflammation to study any harmful effect of DBP exposure on lung tissues. Rats were treated by intragastric administration of DBP (500 mg kg^-1 or 750 mg kg^-1) and/or subcutaneous injection of SFN (4 mg kg^-1). The results of histopathological analysis, cell count, and myeloperoxidase showed that DBP promoted the inflammatory damage of lungs. In the lung tissues, the detection of terminal deoxynucleotidyl transferase dUNT nick end labeling and oxidative stress indices showed that DBP significantly increased the level of apoptosis and oxidative stress. Western blot analysis indicated that DBP raised the expression level of thymic stromal lymphopoietin and reduced the nuclear expression level of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was further verified by quantitative real-time PCR. Meanwhile, DBP treatment markedly up-regulated the inflammatory cytokines such as IL-4 and IL-13, and rat mast cell protease-2, a marker secreted by mast cells (MCs). Conversely, sulforaphane, a Nrf2 inducer, ameliorated the pulmonary damage induced by DBP in the above. Altogether, our data provides a new insight into the impacts of the activation of MCs on the DBP-induced pulmonary toxicity as well as the safety evaluation of DBP.

Endocrine disrupting chemicals in the pathogenesis of hypospadias; developmental and toxicological perspectives

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Penis development is regulated by a tight balance of androgens and estrogens.

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EDCs that impact androgen/estrogen balance during development cause hypospadias.

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Cross-disciplinary collaborations are needed to define a mechanistic link.

Hypospadias is a defect in penile urethral closure that occurs in approximately 1/150 live male births in developed nations, making it one of the most common congenital abnormalities worldwide. Alarmingly, the frequency of hypospadias has increased rapidly over recent decades and is continuing to rise. Recent research reviewed herein suggests that the rise in hypospadias rates can be directly linked to our increasing exposure to endocrine disrupting chemicals (EDCs), especially those that affect estrogen and androgen signalling. Understanding the mechanistic links between endocrine disruptors and hypospadias requires toxicologists and developmental biologists to define exposures and biological impacts on penis development. In this review we examine recent insights from toxicological, developmental and epidemiological studies on the hormonal control of normal penis development and describe the rationale and evidence for EDC exposures that impact these pathways to cause hypospadias. Continued collaboration across these fields is imperative to understand the full impact of endocrine disrupting chemicals on the increasing rates of hypospadias.

The oxidative stress responses caused by phthalate acid esters increases mRNA abundance of base excision repair (BER) genes in vivo and in vitro

The base excision repair (BER) pathway is an important defense response to oxidative DNA damage. It is known that exposures to phthalate esters (PAEs), including Dibutyl phthalate (DBP), Mono-(2-ethylhexyl) phthalate (MEHP), and Di-(2-ethylhexyl) phthalate (DEHP), cause reactive oxygen species-induced DNA damage and oxidative stress. Here, we determined the mRNA levels of BER pathway-related genes (ogg1, nthl1, apex1, parp1, xrcc1, lig3, ung, pcna, polb, pold, fen1, and lig1), pro-apoptotic gene (bax), and apoptotic suppressor gene (bcl2) in different PAEs-exposed zebrafish larvae and HEK293T cells. Further investigations were performed to examine reactive oxygen species (ROS) accumulation, superoxide dismutase (SOD) activity, developmental toxicity, and cell viability after PAEs exposure in vivo and in vitro. The results showed that PAEs exposure can induce developmental abnormalities in zebrafish larvae, and inhibit cell viability in HEK293T cells. Additionally, we found that PAEs exposure results in the accumulation of ROS and the inhibition of SOD activation in vivo and in vitro. Notably, the mRNA levels of BER pathway-related genes (OGG1, NTHL1, APEX1, XRCC1, UNG, POLB, POLD, FEN1) were significantly upregulated after DBP or MEHP exposure, whereas the mRNA levels of NTHL1, UNG, POLB, POLD, and FEN1 were significantly altered in DEHP-treated HEK293T cells. In zebrafish, the mRNA levels of ogg1, pcna, fen1 and lig1 genes were increased after DBP or DEHP exposure, whereas the mRNA levels of nthl1, apex1, parp1, lig3, pcna and polb were decreased after MEHP exposure, respectively. Thus, our findings indicated that PAEs exposure can induce developmental toxicity, cytotoxicity, and oxidative stress, as well as activate BER pathway in vivo and in vitro, suggesting that BER pathway might play critical roles in PAEs-induced oxidative stress through repairing oxidative DNA damage.