Association of Serum 25(OH)D, Cadmium, CRP With All-Cause, Cause-Specific Mortality: A Prospective Cohort Study

Oxidative stress and inflammation mediate the adverse effects of cadmium exposure on all-cause and cause-specific mortality in patients with diabetes and prediabetes

BACKGROUND

The effect of cadmium exposure on mortality risk among individuals with diabetes and prediabetes remains unclear, particularly regarding potential mediation by oxidative stress and inflammation. This study aimed to investigate the associations of blood cadmium levels with all-cause, cardiovascular disease (CVD), and cancer mortality and the mediating effects of oxidative stress and inflammation biomarkers in patients with diabetes and prediabetes.

METHODS

In this prospective cohort study, we analyzed 17,687 adults with diabetes and prediabetes from the National Health and Nutrition Examination Survey (NHANES, 1999-2018). Nine biomarkers related to oxidative stress (gamma-glutamyl transferase [GGT], uric acid [UA], high-density lipoprotein [HDL], UA to HDL ratio [UHR]) and inflammation (neutrophil-lymphocyte ratio [NLR], monocyte-lymphocyte ratio [MLR], neutrophil-monocyte-lymphocyte ratio [NMLR], systemic inflammation response index [SIRI], systemic immune-inflammation index [SII]) were systematically assessed. Kaplan-Meier survival analysis, Cox proportional hazards models, and restricted cubic splines (RCS) were applied to evaluate the association of cadmium with mortality risk. Generalized linear models were used to assess the association of cadmium with oxidative stress and inflammation biomarkers, while Cox regression and RCS evaluated their effects on mortality. Causal mediation analysis identified biological pathways mediated by oxidative stress and inflammation. Stratified and sensitivity analyses were further employed to confirm the robustness of the results.

RESULTS

During 161,047.75 person-years of follow-up, 3562 deaths occurred, including 1214 from CVD and 680 from cancer. Higher blood cadmium levels were associated with increased risks of all-cause mortality (fully adjusted hazard ratio [HR]: 2.17; 95% confidence interval [CI] 1.69-2.79, comparing highest vs. lowest quartile), CVD mortality (HR 2.06; 95% CI 1.41-3.02), and cancer mortality (HR 2.38; 95% CI 1.47-3.85), without evidence of nonlinear relationship. Mediation analyses indicated that UA, NLR, MLR, NMLR, and SIRI partially mediated the associations of cadmium with all-cause and CVD mortality, although the mediated proportions were relatively modest (ranging from 1.4 to 4.8%). Additionally, GGT mediated a small fraction of the associations with all-cause and cancer mortality.

CONCLUSION

Cadmium exposure increases the risk of all-cause, CVD, and cancer mortality in patients with diabetes and prediabetes. Oxidative stress and inflammation appear to partially mediate this adverse effect. These findings emphasize the urgent need for targeted interventions to reduce cadmium-related mortality risks.

RESEARCH INSIGHTS

What is currently known about this topic? Cadmium exposure is linked to increased mortality. Oxidative stress and inflammation are critical in diabetes development and complications. What is the key research question? Does cadmium exposure increase mortality risk in patients with diabetes and prediabetes? Are oxidative stress and inflammation involved in mediating these effects? What is new? Cadmium exposure increases all-cause and cause-specific mortality in diabetes and prediabetes. Oxidative stress and inflammation mediate these associations. How might this study influence clinical practice? Monitor cadmium, oxidative stress, and inflammation to reduce mortality in diabetes and prediabetes.

Interactive association of metals and Life's Essential 8 with mortality in U.S. adults: a prospective cohort study from the NHANES dataset

BACKGROUND

Life's Essential 8 (LE8) is a novel assessment of cardiovascular health (CVH) by evaluating lifestyle, and reports of the associations between LE8 and urinary metals on mortality have been very limited. This study aimed to conduct a prospective cohort study and investigate the combined effects of metals and LE8 on mortality in U.S. adults.

METHODS

This study enrolled participants with complete information on urinary metals, LE8, mortality status, and confounders from the National Health and Nutrition Examination Survey (2005-2018). The Cox regression model, adaptive lasso penalized regression, and restricted cubic spline were used to analyze the individual effects of metals and LE8 on all-cause mortality. The additive and multiplicative interaction scales and quantile g-computation were used to evaluate the interaction and combined effects. Stratified analyses were performed to clarify whether metals and LE8 interacted with other variables to influence all-cause mortality.

RESULTS

A total of 8017 participants were included in this study. The concentrations of cadmium, cobalt, lead, antimony, and thorium were greater in the low CVH group than in the high CVH group [median (µg/L): 0.29 vs. 0.19, 0.36 vs. 0.35, 0.48 vs. 0.39, 0.05 vs. 0.04, and 0.07 vs. 0.06]. The interaction between cadmium and LE8 was statistically significant, with a synergy index of 1.169 (95% CI: 1.004, 1.361). The stratified analyses showed that the interaction between age and LE8 had an impact on all-cause mortality (P for interaction = 0.004).

CONCLUSIONS

In this representative sample of the U.S. population, we found that the combined effect of cadmium, lead, thallium, and LE8 was positively associated with all-cause mortality. Furthermore, the interaction between cadmium and LE8 influenced all-cause mortality. So people should adopt healthy behaviors and reduce heavy metal exposure to minimize the risk of adverse health outcomes.

Environmental Cadmium Exposure Induces an Increase in Systolic Blood Pressure by Its Effect on GFR

Chronic exposure to the nephrotoxic metal pollutant, cadmium (Cd), has been associated with hypertension, but the mechanism by which it raises blood pressure is not understood. We hypothesize that exposure to Cd reduces the glomerular filtration rate (GFR), which in turn causes a rise in blood pressure. Data were collected from 447 Thai subjects with a mean age of 51.1 years, of which 48.8% had hypertension, 15.4% had diabetes, and 6.9% had an estimated GFR (eGFR) below 60 mL/min/1.73 m2 (low eGFR). More than half (58.8%) and 23.9% had moderate and severe tubular proteinuria, respectively. The mean blood and urinary Cd concentrations were 2.75 and 4.23 µg/L, respectively. Doubling of body burden of Cd increased the prevalence odds ratios (POR) for low eGFR and severe tubular proteinuria 41% and 48%, respectively. The POR for hypertension rose twofold in those with blood Cd levels of 0.61–1.69 µg/L or urinary Cd excretion levels ≥ 0.98 µg/g creatinine. In the hypertensive group, the eGFR was inversely associated with age (β = −0.517), the Cd excretion rate (β = −0.177), and diabetes (β = −0.175). By mediation analysis, an increase in SBP was attributable totally to the effect of Cd on GFR. Thus, blood pressure appeared to rise as GFR fell. This finding is consistent with the well-known role of the kidney in long-term blood pressure regulation, and explains a universally high prevalence of hypertension among patients with low eGFR.

The mediation effect of Systemic Immunity Inflammation Index between urinary metals and TOFAT among adults in the NHANES dataset

Systemic Immune Inflammatory Index (SII) is a novel indicator of inflammation. However, no studies have reported the effect of SII on the association between metals and total fat (TOFAT). We aim to investigate the mediated effect of SII on the relationship between urinary metals and TOFAT in a US adult population. This cross-sectional study was conducted among adults with complete information on SII, urine metal concentrations, and TOFAT from the 2011-2018 National Health and Nutrition Examination Survey (NHANES). Multifactorial logistic regression and restricted cubic splines were used to explore the association between urine metal levels and TOFAT. Furthermore, serial mediation analyses were used to investigate the mediating effect of SII on metals and TOFAT. A total of 3324 subjects were included in this study. After adjusting for confounders, arsenic (As), cadmium (Cd), cobalt (Co), cesium (Cs), inorganic mercury (Hg), molybdenum (Mo), manganese (Mn), lead (Pb), antimony (Sb), and thallium(Tl) had negative decreased trends of odds ratios for TOFAT (all P for trend < 0.05). In the total population, we found that Cd, Co, and Tu were positively associated with SII (β = 29.70, 79.37, and 31.08), whereas As and Hg had a negative association with SII. The mediation analysis showed that SII mediated the association of Co with TOFAT, with the β of the mediating effect being 0.9% (95%CI: 0.3%, 1.6%). Our findings suggested that exposure to As, Cd, and Hg would directly decrease the level of TOFAT. However, Co would increase TOFAT, completely mediated by SII, mainly exerted in females rather than males.

Association of C-reactive protein with all-cause and cause-specific mortality in people with gout

AIMS

To test the association of C-reactive protein (CRP) with all-cause and cause-specific mortality in people with gout.

METHODS

This cohort study included 502 participants with gout from the National Health and Nutrition Examination Survey. Multivariate Cox regression analysis, subgroup analysis, and restricted cubic spline (RCS) analyses were utilized to examine the association of CRP levels with all-cause, cardiovascular, and cancer mortality.

RESULTS

After adjusting for multiple variables, Cox regression analysis showed that compared with individuals in the lowest tertile of CRP levels, those in the middle and highest tertiles experienced increases in all-cause mortality risk of 74.2% and 149.7%, respectively. Similarly, the cancer mortality risk for individuals in the highest tertile of CRP levels increased by 283.9%. In addition, for each standard deviation increase in CRP, the risks of all-cause and cancer mortality increased by 25.9% and 35.4%, respectively (P < 0.05). Subgroup analyses demonstrated that the association between CRP levels and all-cause mortality remained significant across subgroups of age (≤ 60 and > 60 years), gender (male), presence or absence of hypertension, non-diabetes, cardiovascular disease, non-cardiovascular disease and non-cancer. Furthermore, the association with cancer mortality was significant in subgroups including males, those without hypertension and cancer, and those with or without diabetes. However, the association with cardiovascular mortality was only significant in the non-hypertension subgroup (P < 0.05). Nonlinear association of CRP with all-cause mortality and linear association with cancer mortality were also confirmed (P for nonlinearity = 0.008 and 0.135, respectively).

CONCLUSIONS

CRP levels were associated with increased all-cause and cancer mortality among individuals with gout.

Modulation of Adverse Health Effects of Environmental Cadmium Exposure by Zinc and Its Transporters

Zinc (Zn) is the second most abundant metal in the human body and is essential for the function of 10% of all proteins. As metals cannot be synthesized or degraded, they must be assimilated from the diet by specialized transport proteins, which unfortunately also provide an entry route for the toxic metal pollutant cadmium (Cd). The intestinal absorption of Zn depends on the composition of food that is consumed, firstly the amount of Zn itself and then the quantity of other food constituents such as phytate, protein, and calcium (Ca). In cells, Zn is involved in the regulation of intermediary metabolism, gene expression, cell growth, differentiation, apoptosis, and antioxidant defense mechanisms. The cellular influx, efflux, subcellular compartmentalization, and trafficking of Zn are coordinated by transporter proteins, solute-linked carriers 30A and 39A (SLC30A and SLC39A), known as the ZnT and Zrt/Irt-like protein (ZIP). Because of its chemical similarity with Zn and Ca, Cd disrupts the physiological functions of both. The concurrent induction of a Zn efflux transporter ZnT1 (SLC30A1) and metallothionein by Cd disrupts the homeostasis and reduces the bioavailability of Zn. The present review highlights the increased mortality and the severity of various diseases among Cd-exposed persons and the roles of Zn and other transport proteins in the manifestation of Cd cytotoxicity. Special emphasis is given to Zn intake levels that may lower the risk of vision loss and bone fracture associated with Cd exposure. The difficult challenge of determining a permissible intake level of Cd is discussed in relation to the recommended dietary Zn intake levels.

Association between serum 25-hydroxyvitamin D and vitamin D dietary supplementation and risk of all-cause and cardiovascular mortality among adults with hypertension

BACKGROUND

The relationship between vitamin D status and mortality among adults with hypertension remains unclear.

METHODS

This prospective cohort study involved a sample of 19,500 adults with hypertension who participated in the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2018. We utilized a weighted COX proportional hazard model to assess the association between vitamin D status and mortality. This statistical model calculates hazard ratios (HR) and their corresponding 95% confidence intervals (95% CI).

RESULTS

The study indicated that lower serum 25(OH)D concentration was associated with an increased risk of all-cause mortality among individuals with hypertension. Specially. Those with concentrations between 25.0 and 49.9 nmol/L (HR = 1.71, 95%CI = 1.22-2.40) and less than 25.0 nmol/L (HR = 1.97, 95%CI = 1.15-3.39) had higher hazard ratios for all-cause mortality. Individuals with hypertension who took vitamin D supplements had a lower risk of all-cause mortality, but not the risk of CVD mortality (HR 0.75, 95%CI 0.54-1.03), compared to those who did not supplement (HR = 0.76, 95%CI = 0.61-0.94). Subgroup analysis further revealed that vitamin D supplementation was associated with a reduced risk of all-cause mortality among individuals without diabetes (HR = 0.65, 95%CI = 0.52-0.81) and individuals without CVD (HR = 0.75, 95%CI = 0.58-0.97), and a decreased risk of CVD mortality among individuals without diabetes (HR = 0.63, 95%CI = 0.45-0.88) and without CVD (HR = 0.61, 95%CI = 0.40-0.92). Furthermore, higher-dose vitamin D supplementation was also associated with a greater reduction in all-cause mortality among hypertensive individuals, and there was the potential synergistic effect of combining normal-dose calcium and vitamin D supplementation, showing a superior effect on mortality compared to low-dose supplementation in adults with hypertension.

CONCLUSIONS

This prospective cohort study demonstrated a significant association between lower serum 25 (OH)D concentration and increased all-cause mortality among adults with hypertension. Furthermore, the study found that vitamin D supplementation had a strong and significantly positive correlation with reduced all-cause and CVD mortality among hypertensive individuals without diabetes or CVD. This positive correlation suggests that vitamin D supplementation could potentially be an effective strategy to reduce the risk of mortality in this specific group of people.

The single and mixed impacts of cadmium, cobalt, lead, and PAHs on systemic immunity inflammation index in male and female

Background

Studies on the association between mixed exposure to common pollutants such as cadmium (Cd), cobalt (Co), lead (Pb), and polycyclic aromatic hydrocarbons (PAHs) with Systemic Immune Inflammatory Index (SII), a novel hemocyte-based inflammatory marker, have not been reported. This study explored the relationship between co-exposure to Cd, Co, Pb, PAHs, and SII.

Methods

In this study, we used data from the National Health and Nutrition Examination Survey and enrolled adults with complete information on Cd, Co, Pb, PAHs, and SII. The linear regression was used to analyze the association of single pollutants with SII. Furthermore, a Bayesian Kernel Machine Regression analysis and a generalized weighted quantile sum regression analysis were used to analyze the association between mixed exposure to Cd, Co, Pb, and six PAHs and SII. We also separated males and females and analyzed the different effects of pollutants on SII, respectively.

Results

5,176 participants were included in the study. After adjusting for age, gender, race, education, smoking, drinking, physical activity, and sedentary, Cd, Co, 1-OHN, 2-OHN and 2-OHF were positive with SII in the total population. Compared with the 50th percentile, the joint effect of pollutants on SII was positive. In the total population, males, and females, the top contaminant with the highest effect weights on SII were Co, Cd, and 1-OHN, respectively. The result of interaction analysis showed that the low concentrations of Cd had an elevation effect on SII in males.

Conclusion

This study found a positive association of mixed exposure to Cd, Co, Pb, and six PAHs with SII, which occurred mainly in females.

Association of serum 25-hydroxyvitamin D concentrations with all-cause mortality among individuals with kidney stone disease: the NHANES database prospective cohort study

Background

The purpose of this study was to investigate the correlation between serum 25(OH)D concentrations and all-cause mortality in patients with kidney stone disease (KSD) as the effects of a deficiency in 25-hydroxyvitamin D on KSD patients are currently unclear.

Methods

For our prospective cohort study, we included 2,916 participants from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. The National Death Index (NDI) was utilized to identify all causes of death and cause-specific mortality until December 31, 2018. We calculated hazard ratios (HR) and 95% confidence intervals (CIs) using multivariate Cox regression models.

Results

During the 18,859 person-years of follow-up, a total of 375 fatalities occurred, including 83 deaths from cardiovascular disease (CVD) and 79 deaths from cancer. At baseline, individuals with higher blood 25(OH)D concentrations had lower levels of glucose, glycohemoglobin, CRP, and insulin, as well as higher levels of HDL cholesterol (P < 0.01). In the fully adjusted model (Model 3), compared to the group with the lowest 25(OH)D concentrations, those with serum 25(OH)D concentrations ≥75 nmol/L had hazard ratios (HRs) and 95% confidence intervals (CIs) of 0.48 (0.26, 0.87) for all-cause mortality (P=0.02, P for trend = 0.02). The association between serum 25(OH)D concentrations and all-cause mortality in KSD patients was found to be significantly non-linear. A 7% decrease in the risk of death from all causes was observed for each unit-nmol/L increase in serum 25(OH)D concentrations when the concentrations were below 27.7 nmol/L (P < 0.05).

Conclusion

Based on the findings, KSD patients with insufficient serum 25(OH)D concentrations were at a higher risk of all-cause mortality. Therefore, it is crucial to maintain sufficient blood 25(OH)D concentrations and prevent 25(OH)D insufficiency in order to extend the lifespan of KSD patients.

Mitigation of Cadmium Toxicity through Modulation of the Frontline Cellular Stress Response

Cadmium (Cd) is an environmental toxicant of public health significance worldwide. Diet is the main Cd exposure source in the non-occupationally exposed and non-smoking populations. Metal transporters for iron (Fe), zinc (Zn), calcium (Ca), and manganese (Mn) are involved in the assimilation and distribution of Cd to cells throughout the body. Due to an extremely slow elimination rate, most Cd is retained by cells, where it exerts toxicity through its interaction with sulfur-containing ligands, notably the thiol (-SH) functional group of cysteine, glutathione, and many Zn-dependent enzymes and transcription factors. The simultaneous induction of heme oxygenase-1 and the metal-binding protein metallothionein by Cd adversely affected the cellular redox state and caused the dysregulation of Fe, Zn, and copper. Experimental data indicate that Cd causes mitochondrial dysfunction via disrupting the metal homeostasis of this organelle. The present review focuses on the adverse metabolic outcomes of chronic exposure to low-dose Cd. Current epidemiologic data indicate that chronic exposure to Cd raises the risk of type 2 diabetes by several mechanisms, such as increased oxidative stress, inflammation, adipose tissue dysfunction, increased insulin resistance, and dysregulated cellular intermediary metabolism. The cellular stress response mechanisms involving the catabolism of heme, mediated by heme oxygenase-1 and -2 (HO-1 and HO-2), may mitigate the cytotoxicity of Cd. The products of their physiologic heme degradation, bilirubin and carbon monoxide, have antioxidative, anti-inflammatory, and anti-apoptotic properties.