Comparative Evaluation of Essential and Toxic Metals in the Blood and Scalp Hair of Arthritis Patients and Healthy Subjects

Abstract

Arthritis is a group of autoimmune diseases in which the body immune system starts attacking joints and other related tissues. There are significant evidences that essential and toxic metals played important role in aetiology of the diseases. The current study is designed to evaluate selected essential and toxic metals (Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Pb and Zn) in the scalp hair and blood of newly diagnosed arthritis patients in comparison with matching healthy subjects. The selected types of arthritis patients included osteoarthritis (OA), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), spondyloarthropathy (SPA) and systemic lupus erythematosus (SLE). Nitric acid and perchloric acid based wet digestion procedure was used for the solubilization of scalp hair and blood samples, while quantification of the metals was performed by using flame atomic absorption spectrophotometer. Among the selected metals, Ca (2119 μg/g), Mg (214.8 μg/g), Zn (189.2 μg/g), Fe (60.95 μg/g) and Pb (36.02 μg/g) were predominantly higher in the scalp hair of OA patients, however in case of healthy subjects, Ca (2034 μg/g), Zn (299.0 μg/g), Mg (264.6 μg/g), Fe (35.57 μg/g) and Pb (34.12 μg/g) showed relatively higher average levels in the scalp hair. Likewise dominant mean metal levels were found for Ca (2380 μg/g), Mg (243.3 μg/g), Zn (204.1 μg/g), Fe (63.83 μg/g), Pb (33.89 μg/g) and Cr (25.86 μg/g) in the scalp hair of RA patients but matching healthy subjects showed higher average concentrations of Ca (2541 μg/g), Mg (279.0 μg/g), Zn (245.7 μg/g), Fe (90.44 μg/g), Pb (29.00 μg/g) and Cu (22.22 μg/g). Scalp hair of JIA patients exhibited higher mean levels for Ca (1685 μg/g), Mg (176.3 μg/g), Zn (164.9 μg/g), Fe (154.4 μg/g), Pb (35.05 μg/g), Co (24.15 μg/g), Cu (22.21 μg/g) and Cr (18.03 μg/g). Similarly, relatively higher average levels were noted for Ca (1874 μg/g), Zn (218.8 μg/g), Mg (161.2 μg/g), Fe (103.1 μg/g), Pb (50.30 μg/g), Co (17.95 μg/g), Cr (17.57 μg/g) and Cu (17.01 μg/g) in the scalp hair of SPA patients. The scalp hair of SLE patients exhibited dominant mean metal levels for Ca (2050 μg/g), Zn (223.1 μg/g), Mg (192.5 μg/g), Fe (89.79 μg/g), Pb (47.32 μg/g), Cu (35.28 μg/g), Co (30.44 μg/g) and Cr (22.23 μg/g). Significantly higher (p < 0.05) average concentrations of Ca, Cd, Co, Cr, Mn and Pb were found in the scalp hair of OA patients than the healthy subjects. Similarly, Cd, Co, Cr, Mn and Pb exhibited higher concentrations in the scalp hair of RA patients, whereas higher mean levels of Cd, Co, Cr, Cu, Fe, Mn and Pb were noted in the scalp hair of JIA patients. Nonetheless, elevated average levels for Cd, Co, Cr, Mn and Pb were found in SPA patients, but mean contents of Cd, Co, Cr, Cu, Fe, Mn and Pb were noted higher in the scalp hair of SLE patients compared with the healthy subjects. The correlation study revealed significantly diverse mutual associations among the selected metals in the scalp hair of various types of arthritis patients and counterpart healthy subjects. Spearman correlation coefficient matrix of the selected metals showed strong mutual associations among Pb-Cd, Cr-Co, Mn-Cu and Pb-Co, while, inverse relationships were found among Ca-Mn, Ca-Pb and Mg-Cd in the scalp hair of OA patients. Appreciably stronger positive correlations were noted for Mn-Cd, Pb-Cd, Pb-Co, Fe-Cr, Fe-Cu, Mn-Cu, Mg-Ca, Mn-Fe and Cr-Cd in the scalp hair of RA patients. On the other hand in the scalp hair of JIA patients strong positive correlations were noted for Cu-Cd, xxix Pb-Cu, Pb-Ca, Fe-Cu, Zn-Ca, Pb-Cd and Cu-Ca. The scalp hair of SPA patients exhibited stronger correlations among Cu-Cd, Mg-Ca, Zn-Cu, Zn-Cd, Mg-Cu, Zn-Mg and Zn-Ca. In case of the scalp hair of SLE patients noticeable positive correlations were noted for Ca- Cr, Mn-Cd, Zn-Mn, Cr-Cd and Mn-Cr. Principal component analysis (PCA) and cluster analysis (CA) of the metal data manifested significantly divergent apportionment of the metals in the scalp hair of various arthritis patients compared with the healthy subjects. The distribution of selected metals in the scalp hair of above mentioned types of arthritis patients and healthy subjects were also investigated for any viable differences with respect to gender, habitat, food habits & smoking habits and several significant differences were observed in both groups. Most of the metals exhibited random distribution in the blood of various arthritis patients and healthy subjects. In the blood of OA patients, comparatively higher levels were noted for Fe (239.7 μg/g), Ca (159.1 μg/g), Mg (29.02 μg/g) and Pb (5.729 μg/g), while the healthy subjects depicted higher concentrations for Fe (305.4 μg/g), Ca (169.5 μg/g), Mg (41.66 μg/g), Zn (8.934 μg/g) and Pb (4.092 μg/g). On the average basis dominant mean levels were found for Fe (230.1 μg/g), Ca (190.6 μg/g), Mg (30.54 μg/g) and Pb (7.825 μg/g) in the blood of RA patients, while JIA patients showed elevated mean levels of Fe (500.7 μg/g), Ca (69.92 μg/g), Mg (29.30 μg/g), Zn (6.002 μg/g), Pb (5.415 μg/g) and Co (3.129 μg/g). In the blood of SPA patients, relatively higher levels were observed for Fe (392.4 μg/g), Ca (66.07 μg/g), Mg (28.17 μg/g), Pb (5.553 μg/g), Zn (5.037 μg/g), Cr (4.173 μg/g), Co (3.695 μg/g) and Cu (1.966 μg/g), whereas dominant mean levels were noted for Fe (321.0 μg/g), Ca (47.24 μg/g), Mg (31.64 μg/g), Zn (7.721 μg/g), Pb (7.185 μg/g), Co (4.516 μg/g), Cr (2.795 μg/g) and Cu (2.689 μg/g) in the blood of SLE patients. Majority of the metals (Cd, Co, Cr, Mn and Pb) exhibited relatively higher contribution in the blood of OA patients than the healthy subjects, while RA patients showed higher levels of Cd, Co, Cr, Cu, Mn and Pb than the healthy subjects. Fairly high levels of Cd, Co, Cr, Cu, Fe, Mn, Pb and Zn were found in the blood of JIA patients, while mean levels of Cd, Co, Cr, Cu, Fe and Mn were higher in the blood of SPA patients. As observed in the previous case, the correlation study pointed out considerable disparities in the mutual relationships of the metal levels in the blood of the patients and healthy subjects. Multivariate methods including PCA and CA showed significantly divergent apportionment and multiple relations among the metals in the blood of various types of arthritis patients in comparison with counterpart healthy subjects. Average metal levels in each matrix of the patients and healthy subjects were also evaluated based on gender, habitat, dietary habits and smoking habits of the patients and healthy subjects; noticeable differences were observed in all categories. The average levels of selected metals were also compared for the above given types of the arthritis patients; this comparison demonstrated significantly differing variations among various types of arthritis patients. Overall, the study indicated significantly diverse pattern of relative distribution, mutual relationships and multivariate apportionment of the selected essential and toxic metals in the scalp hair and blood of above mentioned types of arthritis patients compared with the healthy subjects.