Lead and cadmium exposure induces male reproductive dysfunction by modulating the expression profiles of apoptotic and survival signal proteins in tea-garden workers

Cadmium disrupts spermatogenic cell cycle via piRNA-DQ717867/p53 pathway

Cadmium (Cd) is a harmful environmental pollutant that disrupts public health, including respiratory, digestive, and reproductive systems. In this study, male rats were exposed to CdCl2 at a dose of 3 mg/kg by oral for 28 days to investigate the impact on spermatogenesis. Testis tissue samples were collected after sacrifice, and piRNA expression levels were measured using piRNA microarray and qPCR. PiRNAs, specialized molecules involved in spermatogenesis, were examined. CdCl2 exposure led to disrupted piRNA expression, particularly in piRNA-DQ759395 in rats. This piRNA was found to have a binding site with p53, and a similar piRNA-DQ717867 was discovered in mice. In GC-2spd cells, CdCl2 exposure increased piRNA-DQ717867 expression, which resulted in cell cycle arrest and abnormal expression of cell cycle-related proteins. The activation of p53-related pathways and disruptions in cell cycle regulation were also observed. Antagomir-717867 transfections and PFT-a pretreatment in GC-2spd cells supported the involvement of piRNA-DQ717867 in regulating cell cycle-related proteins. This study suggests that Cd exposure induces abnormal expression of piRNA-DQ759395 in rat testis and that piRNA-DQ717867 may regulate p53, causing cell cycle abnormalities in GC-2spd cells. These findings help understand the mechanisms of male reproductive toxicity caused by Cd exposure and emphasize the role of piRNAs in cell cycle regulation and male reproductive health.

Insights into the mechanism of transcription factors in Pb2+-induced apoptosis

The health risks associated with exposure to heavy metals, such as Pb2+, are increasingly concerning the public. Pb2+ can cause significant harm to the human body through oxidative stress, autophagy, inflammation, and DNA damage, disrupting cellular homeostasis and ultimately leading to cell death. Among these mechanisms, apoptosis is considered crucial. It has been confirmed that transcription factors play a central role as mediators during the apoptosis process. Interestingly, these transcription factors have different effects on apoptosis depending on the concentration and duration of Pb2+ exposure. In this article, we systematically summarize the significant roles of several transcription factors in Pb2+-induced apoptosis. This information provides insights into therapeutic strategies and prognostic biomarkers for diseases related to Pb2+ exposure.

The influence of lead exposure on male semen parameters: a systematic review and meta-analysis

Lead (Pb) is a metal with a widespread diffusion in the environment. Pb tends to accumulate in the human body and, as a consequence, semen alterations can be present in exposed workers or general population. The aim of the present study is to evaluate the effect on semen parameters among healthy men exposed to environmental or occupational Pb. A systematic literature search was performed on November 12^th, 2022, through MEDLINE via PubMed, Scopus, and Embase. Observational studies comparing semen parameters in men exposed to Pb and those not exposed were included. Sperm parameters were pooled using the Cochran-Mantel-Haenszel Method with a random effect model. The weighted mean difference (WMD) was used as a summary measure. Statistical significance was set at p-value <0.05 Ten papers were included. Pb exposure was associated with a significant reduction in semen volume (WMD -0.76ml.95% CI -1.47, -0.05, p=0.04), sperm concentration (WMD -0.63 ×10⁶/ml 95% CI -1.15, -0.12, p=0.02), total sperm count (WMD -1.94 ×10⁶ 95% CI -3. 77, -0.11, p=0.04), sperm vitality (WMD -2.18% 95% CI -3.92, -0.45, p=0.01), and total sperm motility (WMD -1.31% 95% CI -2.33, -0.30, p=0.01). No difference was found in sperm normal morphology, progressive motility, and seminal viscosity. This review demonstrated the negative effect of Pb exposure on most of semen parameters. Given the diffuse exposure to this metal of the general population, public health concerns should be considered and exposed workers should be assessed to evaluate their semen. DATA AVAILABILITY STATEMENT: Data will be provided by the corresponding author upon a reasonable request.

Cadmium: A Focus on the Brown Crab (Cancer pagurus) Industry and Potential Human Health Risks

Cadmium is a major health risk globally and is usually associated with pollution and anthropogenic activity. The presence of cadmium in food is monitored to ensure that the health and safety of consumers are maintained. Cadmium is ubiquitous in the Asian and Western diets, with the highest levels present in grains, leafy greens, and shellfish. As part of their natural lifecycle of moulting and shell renewal, all crustaceans-including the brown crab (Cancer pagurus)-bioaccumulate cadmium from their environment in their hepatopancreas. The brown crab is an important species to the crab-fishing industries of many European countries, including Ireland. However, the industry has come under scrutiny in Europe due to the presence of cadmium in the brown crab meat intended for live export to Asia. This review explores evidence regarding the effects of cadmium consumption on human health, with a focus on the brown crab. Differences in cadmium surveillance have given rise to issues in the crab industry, with economic consequences for multiple countries. Currently, evidence suggests that brown crab consumption is safe for humans in moderation, but individuals who consume diets characterised by high levels of cadmium from multiple food groups should be mindful of their dietary choices.

An Overview of Essential Microelements and Common Metallic Nanoparticles and Their Effects on Male Fertility

Numerous factors affect reproduction, including stress, diet, obesity, the use of stimulants, or exposure to toxins, along with heavy elements (lead, silver, cadmium, uranium, vanadium, mercury, arsenic). Metals, like other xenotoxins, can cause infertility through, e.g., impairment of endocrine function and gametogenesis or excess production of reactive oxygen species (ROS). The advancement of nanotechnology has created another hazard to human safety through exposure to metals in the form of nanomaterials (NMs). Nanoparticles (NPs) exhibit a specific ability to penetrate cell membranes and biological barriers in the human body. These ultra-fine particles (<100 nm) can enter the human body through the respiratory tract, food, skin, injection, or implantation. Once absorbed, NPs are transported to various organs through the blood or lymph. Absorbed NPs, thanks to ultrahigh reactivity compared to bulk materials in microscale size, disrupt the homeostasis of the body as a result of interaction with biological molecules such as DNA, lipids, and proteins; interfering with the functioning of cells, organs, and physiological systems; and leading to severe pathological dysfunctions. Over the past decades, much research has been performed on the reproductive effects of essential trace elements. The research hypothesis that disturbances in the metabolism of trace elements are one of the many causes of infertility has been unquestionably confirmed. This review examines the complex reproductive risks for men regarding the exposure to potentially harmless xenobiotics based on a series of 298 articles over the past 30 years. The research was conducted using PubMed, Web of Science, and Scopus databases searching for papers devoted to in vivo and in vitro studies related to the influence of essential elements (iron, selenium, manganese, cobalt, zinc, copper, and molybdenum) and widely used metallic NPs on male reproduction potential.

Multiple Targets of Toxicity in Environmental Exposure to Low-Dose Cadmium

Dietary assessment reports and population surveillance programs show that chronic exposure to low levels of environmental cadmium (Cd) is inevitable for most people, and adversely impacts the health of children and adults. Based on a risk assessment model that considers an increase in the excretion of β₂-microglobulin (β₂M) above 300 μg/g creatinine to be the "critical" toxicity endpoint, the tolerable intake level of Cd was set at 0.83 µg/kg body weight/day, and a urinary Cd excretion rate of 5.24 µg/g creatinine was considered to be the toxicity threshold level. The aim of this review is to draw attention to the many other toxicity endpoints that are both clinically relevant and more appropriate to derive Cd exposure limits than a β₂M endpoint. In the present review, we focus on a reduction in the glomerular filtration rate and diminished fecundity because chronic exposure to low-dose Cd, reflected by its excretion levels as low as 0.5 µg/g creatinine, have been associated with dose-dependent increases in risk of these pathological symptoms. Some protective effects of the nutritionally essential elements selenium and zinc are highlighted. Cd-induced mitochondrial dysfunction is discussed as a potential mechanism underlying gonadal toxicities and infertility.

Impact of Heavy Metals on Human Male Fertility-An Overview

Heavy metals are endocrine disruptors which interfere with processes mediated by endogenous hormones of the organism, negatively affecting endocrine functions. Some studies have correlated heavy metal exposure with male infertility. However, the number of studies conducted on humans are limited. Therefore, the aim of this study is to summarize the current knowledge on how heavy metals influence human male fertility. Hence, three distinct databases were consulted—PubMed, Scopus and Web of Science—using single keywords and combinations of them. The total number of identified articles was 636. Nevertheless, by using the inclusion and exclusion criteria, 144 articles were finally included in this work. Results display that the development of adequate instruments for heavy metal assessment may play an important function in human male fertility diagnosis and treatment. Furthermore, clinical trials could be useful to confirm the role of heavy metals in human male fertility diagnosis. Overall, further research is required to fully understand the molecular and cellular basis of the influence of environmental and occupational exposure to heavy metals on human male infertility and reproductive outcomes.

Comprehensive Review of Cadmium Toxicity Mechanisms in Male Reproduction and Therapeutic Strategies

Cadmium (Cd) has been widely studied as an environmental pollutant for many years. Numerous studies have reported that Cd exposure causes damage to the heart, liver, kidneys, and thyroid in vivo. The emerging evidence suggests that Cd exposure induces damage on male reproductive system, which is related to oxidative stress, inflammation, steroidogenesis disruption, and epigenetics. Current preclinical animal studies have confirmed a large number of proteins and intracellular signaling pathways involved in the pathological process of Cd-induced male reproductive damage and potential measures for prophylaxis and treatment, which primarily include antioxidants, anti-inflammatory agents, and essential ion supplement. However, explicit pathogenesis and effective treatments remain uncertain. This review collects data from the literatures, discusses the underlying mechanisms of Cd-induced toxicity on male reproductive function, and summarizes evidence that may provide guidance for the treatment and prevention of Cd-induced male reproductive toxicity.