The evaluation of cadmium and other metals in smoking patients with different joint damage

The impact of cadmium on joint damage caused by smoking

Abstract

Introduction. Exposure to cadmium (Cd) through cigarette smoke can negatively affect the joints by inducing an imbalance in the levels of essential trace metals such as Zinc (Zn), Manganese (Mn), Copper (Cu), Iron (Fe), and Selenium (Se), which are necessary for cartilage maintenance. Nevertheless, little is known about the presence of Cd in cartilage and synovial fluid in patients with ligament injury (LI) or osteoarthritis (OA), especially in smokers, as well as its impact on other trace metals. Objective: To compare the concentrations of Cd, Zn, Mn, Cu, Fe, and Se in peripheral blood (PB), synovial fluid (SF), and cartilage (CAR) between smoking and non-smoking patients with LI and OA. Methodology: A total of 46 samples collected between 2020 and 2022 at the National Institute of Rehabilitation "Luis Guillermo Ibarra Ibarra" were analyzed. Participants were classified into four groups: non-smoking LI (n=8), smoking LI (n=3), non-smoking OA (n=21), and smoking OA (n=14). The diagnosis of knee OA was based on the criteria of the American College of Rheumatology. Metal concentrations were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Due to the lack of normality in the data, non-parametric tests (Kruskal-Wallis and Dunn’s post-hoc comparisons) and Spearman’s correlation coefficient were used. Results: Significant differences were observed in age, smoking index, and pain level among the groups. The smoking OA group (OA-S) showed higher tobacco exposure and greater pain. Additionally, 35.71% of OA-S had grade 4 OA, compared to 4.76% in non-smoking OA patients (OA-NS). Cd concentrations were significantly higher in all three types of tissue analyzed in OA-S. In PB, Cd was higher in OA-S (0.943 ng/mL) compared to OA-NS (0.086 ng/mL) and LI-NS (0.106 ng/mL). In SF, OA-S showed significantly higher Cd concentrations (0.103 ng/mL) compared to LI-NS (0.056 ng/mL). In cartilage, OA-S also presented the highest levels of Cd (25.28 ng/g) compared to OA-NS (15.29 ng/g) and LI (0 ng/g). Moreover, OA-S showed elevated concentrations of Zn, Cu, and Se. Positive correlations were observed between Cd levels in PB and Zn, Fe, Cu, Mn, and Se levels in CAR, particularly in the smoking groups. Conclusion: Smoking in OA patients is associated with greater Cd accumulation and alterations in the levels of other trace metals, compared to patients with LI. The correlation between Cd and other metals suggests a possible compensatory response of the body to oxidative stress. Further studies exploring inflammatory cytokines, antioxidant enzymes, and molecules associated with cartilage degradation are needed to better understand the relationship between metal imbalance and joint pathophysiology in smokers with OA.