Mineral deficiency effects on the generation of cytotoxic T-cells and T-helper cell factors in vitro

Relationship between copper and immunity: The potential role of copper in tumor immunity

Copper is an essential trace element in an organism, and changes in copper levels in vivo often indicate a diseased state. Copper and immunity have been discussed since the last century, with copper deficiency significantly affecting the development and function of the immune system, such as increased host susceptibility to various pathogens, decreased number and impaired function of neutrophils, reduced antibacterial activity of macrophages, decreased proliferation of splenocytes, impaired B cell ability to produce antibodies and impaired function of cytotoxic T lymphocyte and helper T cells. In the past 20 years, some studies have shown that copper ions are related to the development of many tumors, including lung cancer, acute lymphoid leukaemia, multiple myeloma and other tumors, wherein copper ion levels were significantly elevated, and current studies reveal that copper ions are involved in the development, growth and metastasis of tumors through various pathways. Moreover, recent studies have shown that copper ions can regulate the expression of PD-L1, thus, attention should be paid to the important role of copper in tumor immunity. By exploring and studying copper ions and tumor immunity, new insights into tumor immunity could be generated and novel therapeutic approaches to improve the clinical prognosis of patients can be provided.

Inactivation of TRPM7 kinase in mice results in enlarged spleens, reduced T-cell proliferation and diminished store-operated calcium entry

T lymphocytes enlarge (blast) and proliferate in response to antigens in a multistep program that involves obligatory cytosolic calcium elevations. Store-operated calcium entry (SOCE) pathway is the primary source of Ca²⁺ in these cells. Here, we describe a novel modulator of blastogenesis, proliferation and SOCE: the TRPM7 channel kinase. TRPM7 kinase-dead (KD) K1646R knock-in mice exhibited splenomegaly and impaired blastogenic responses elicited by PMA/ionomycin or anti-CD3/CD28 antibodies. Splenic T-cell proliferation in vitro was weaker in the mutant compared to wildtype littermates. TRPM7 current magnitudes in WT and KD mouse T cells were, however, similar. We tested the dependence of T-cell proliferation on external Ca²⁺ and Mg²⁺ concentrations. At a fixed [Mg²⁺_o] of ~0.4 mM, Ca²⁺_o stimulated proliferation with a steep concentration dependence and vice versa, at a fixed [Ca²⁺_o] of ~0.4 mM, Mg²⁺_o positively regulated proliferation but with a shallower dependence. Proliferation was significantly lower in KD mouse than in wildtype at all Ca²⁺ and Mg²⁺ concentrations. Ca²⁺ elevations elicited by anti-CD3 antibody were diminished in KD mutant T cells and SOCE measured in activated KD splenocytes was reduced. These results demonstrate that a functional TRPM7 kinase supports robust SOCE, blastogenesis and proliferation, whereas its inactivation suppresses these cellular events.

Expression of the p53 tumor suppressor gene is up-regulated by depletion of intracellular zinc in HepG2 cells

Expression and activation of the p53 tumor suppressor protein are modulated by various cellular stimuli. The objective of this work was to examine the influence of zinc depletion on the expression of p53 in HepG2 cells. Two different low Zn (ZD) media, Zn-free Opti-MEM and a ZD medium containing Chelex-100 treated serum, were used to deplete cellular zinc over one passage. Cellular zinc levels of ZD cells were significantly lower than in their controls in both the Opti-MEM and Chelex studies. p53 mRNA abundance was 187% higher in ZD Opti-MEM cells and >100% higher in ZD Chelex cells compared with their respective controls. To examine whether the effects were specific to zinc depletion, a third, zinc-replenished group (ZDA) was included in the Opti-MEM study in which cells were cultured in ZD media for nearly one passage before a change was made to zinc-adequate (ZA) medium for the last 24 h. Zinc levels in the ZDA cells were significantly higher than in ZD cells, and p53 mRNA abundance was normalized to control levels. Nuclear p53 protein levels were >100% higher in the ZD Opti-MEM cells than in ZA cells. Interestingly, the ZDA Opti-MEM cells had significantly lower levels of nuclear p53 protein than both the ZA and ZD cells. These data suggest that expression of p53, a critical component in the maintenance of genomic stability, may be affected by reductions in cellular zinc.

Apolipoprotein A-I gene expression is regulated by cellular zinc status in hep G2 cells

The influence of Zn on the expression of the apolipoprotein A-I (apoA-I) gene in Hep G2 cells was examined. Zn depletion was achieved with a low-Zn (ZD) medium prepared from Zn-free growth medium (Opti), a ZD medium containing Chelex 100-extracted fetal bovine serum (CHE), and a medium containing chelator 1, 10-phenanthroline (OP). Compared with those for their respective controls, cellular Zn levels were reduced by 55, 48, and 46% and apoA-I mRNA abundances were reduced by 20, 29, and 28% in Opti, CHE, and OP systems, respectively, after one passage in ZD media or 24 h in OP medium. To establish the specificity of Zn treatment, groups of ZD cells were treated with their respective control media for the last 24 h (ZDA) or normal cells were cultured with OP medium supplemented with Zn (OP-Zn). ZDA treatments partially normalized cellular Zn levels in the Opti system and restored or elevated apoA-I mRNA levels in the Opti or CHE system, respectively. Similarly, the OP-Zn treatment restored the cellular Zn and apoA-I mRNA levels. Furthermore, one passage of culture with Zn-supplemented media in both the Opti and CHE systems resulted in higher cellular Zn and apoA-I mRNA levels than those for controls. Most significantly, short-term high-Zn induction to normal cells markedly elevated the cellular Zn (3-fold) and apoA-I mRNA (5-fold) levels. Data derived from this study strongly suggest that the expression of apoA-I is regulated by cellular Zn status.

Antimicrobial screening of zinc in the absence or presence of oleoresins and various resin acids

Zinc and oleoresins are the main components of several wound dressings, and are also frequently used in root canal treatment. The in vitro antibacterial effects of zinc, six highly purified resin acids and two commercial oleoresins alone or combined in varying proportions were analysed. Oleoresins are composed of approximately 90% resin acids and the most common acids were included in this study. The antibacterial activity of the various chemicals was estimated using a Bioscreen robot analyser, which allowed 24 h kinetic documentation of bacterial growth. The bacteria employed were reference species commonly occurring on human skin or of oral origin. Zinc as well as the oleoresins and the pure resin acids all showed antibacterial activity when present in growth media, but the sensitivity of the bacteria varied. The presence of resin acids and oleoresins increased the antibacterial effect of zinc to varying degrees depending on the combination and the bacterial species tested. The results of the present study indicate that zinc, resin acids, or oleoresins alone, as well as combined, show antibacterial activity against selected aerobic Gram-positive and anaerobic Gram-negative bacteria.

Zinc in etiology of periodontal disease

Microbial plaque is the main etiological factor of periodontal disease. The bacterial polysaccharides stimulate gingival neutrophils and macrophages to interleukin-1 (IL-1) production. IL-1 causes a complex of redistribution processes with liver as the central organ. Accumulation of zinc in liver and their copper and ceruloplasmin production also elicits increase of copper and decrease of zinc in gingiva. The elevated level of copper in connection with zinc deficiency in gingiva causes the increase of permeability of gingival epithelium for bacteria. The stimulated inflammatory infiltrate produces more IL-1 and the vicious circle is complete.

Serum trace element levels in HIV-infected subjects

The absolute number of T4 cells and the serum concentrations of Ca, Cu, Fe, K, Mg, P, Se, and Zn were determined in 59 Walter-Reed staged, HIV-infected men, compared to healthy controls, serum levels of Ca, Cu, and Fe were significantly higher, those of P and Se significantly lower in the HIV-infected subjects. In the HIV-infected cases, but not in the controls, the concentrations of Se and Zn, of Ca with Cu and Fe, and of Fe with P, were directly correlated. In the controls, the correlation between the levels of K and Mg was direct, and inverse between those of Zn and P. Trace element levels did not significantly correlate with WR-stage. However, the absolute number of T4 cells was directly correlated with the serum Mg concentration.

Advances in the role of minerals in immunobiology

Immunology and our understanding of its various cells, immunoglobulins and lymphokines are recent events that date from the work of Pasteur and Metchnikoff in the late nineteenth century. Experimental evidence has shown the importance of adequate dietary protein and vitamins. The present review examines past and recent experimental evidence for the role of minerals in the functioning of the immune system. Included is in vivo and in vitro information on the macrominerals; calcium and magnesium, the micro-(trace) minerals; iron, zinc, copper, and selenium as they affect various components of the immune system. The effects of gold as either gold-thiomaleate or gold-thioglucose on selenium is also reviewed.

The immune status of healthy centenarians

The immune status of 17 healthy individuals 100-103 years of age (centenarians) was investigated. Qualitative values for immunoglobulins IgG, IgM, IgA, and IgE were within normal ranges for subjects more than 60 years of age with the exception of elevated IgM in one individual. Cell marker studies employing a panel of 27 monoclonal antibodies delineating T and B lymphocytes, monocytes, natural killer cells, granulocytes, and functional and developmental subsets of each were performed to phenotype the peripheral blood leukocytes. Although the total lymphocyte count was normal in every subject, the numbers of T4-positive helper-inducer T lymphocytes were profoundly depressed, as were responses to the mitogen phytohemagglutinin and interleukin-2 production. Activated immature T lymphocytes and the number of cells bearing the phenotype of natural killer cells were increased, but natural killer cell activity was normal. Early B lymphocytes were also increased. The relative concentration of monocytes was normal. Taken together these findings indicate that the immune system in centenarians is similar to that in younger but still elderly individuals, i.e., discriminating T-lymphoid functions are reduced in association with an apparent failure of some T, B, and natural killer cells to differentiate to functional maturity.

The effect of copper deficiency on the resistance of mice to infection with Pasteurella haemolytica

Mice adjudged copper deficient on the basis of significantly decreased blood and tissue copper content and superoxide dismutase activity, but generally showing no clinical signs of deficiency, were infected intraperitoneally with Pasteurella haemolytica. In 3 separate experiments the LD50 for deficient animals was significantly depressed below that of copper-sufficient controls. Furthermore, in mice surviving challenge at doses near to the LD50, spleen weights were significantly increased and body temperatures depressed in the copper-deficient animals. These results indicate that subclinical copper deficiency in the mouse, is associated with an increased susceptibility to experimental infections with P. haemolytica.

Effects of antigen stimulation and interleukin-1 on in vivo splenic zinc changes in the A/J mouse

The roles of zinc in immune responses continue to be defined and its impact on a broadening list of immune functions reported. Fundamental to the operation of zinc-dependent processes may be shifts in tissue zinc. Since the spleen is a site of activation, proliferation, and differentiation of lymphocytes, we examined changes in copper and zinc levels in spleens of antigen-stimulated A/J mice. Antigen stimulation with human immunoglobulin G and heat killed Staphylococcus aureus was compared with the actions of a nonantigenic inflammatory agent CaCl2. Between-group variations in copper and zinc with antigen treatment were compared in heart, liver, and spleen tissues. The zinc contents of spleens from antigen-treated mice were elevated, as were liver levels of the essential trace element. There were no significant increases in copper levels associated with antigen treatment. CaCl2-treated animal spleens demonstrated decreases in spleen copper and zinc content that were related to weight changes in the spleens, but not to specific treatment effects. Changes were suggestive of Interleukin-1 (IL-1) actions, which led to direct studies of IL-1 actions on splenic zinc. Partially purified IL-1 was injected into the tail vein and heart of A/J mice; liver and spleen zinc levels were determined 16 and 40 hours after injection. Significant increases in liver and splenic zinc concentrations were measured at both time intervals after IL-1 treatment. Antigen stimulation and, more directly IL-1, were related to stimulated increases in splenic zinc.(ABSTRACT TRUNCATED AT 250 WORDS)