Solo Kuvibidila

In vivo and in vitro iron deficiency reduces protein kinase C activity and translocation in murine splenic and purified T cells

We investigated the effects of iron deficiency anemia, iron repletion, and iron chelation by deferoxamine on protein kinase C (PKC) activity, an enzyme that plays a crucial role on T lymphocyte proliferation. The study involved 23 control (C), 18 pairfed (PF), and 24 iron deficient (ID) mice or ID mice that were repleted for 3 (n = 14), 7 (n = 17), or 14 (n = 14) days. The low iron (0.09 mmol iron/kg) and iron‐supplemented (0.9 mmol iron/kg) diets were fed to mice for 53 days. Mean hemoglobin, hematocrit, and liver iron stores of ID mice were one third of those of C mice. Lymphocyte proliferation was reduced (P < 0.05) in spleen and purified T cells in ID but not PF mice. In concanavalin A, phytohemagglutinin, and anti‐CD3 antibody‐treated and untreated cells that were incubated in serum‐free and serum‐containing medium, PKC activity was significantly (P < 0.05) reduced in ID but not PF mice and returned to normal before correction of anemia. In mitogen‐treated cells, while the ratios of membrane‐bound to cytosol activity increased nearly seven‐fold (from 0.4–0.63 in resting cells to 1.43–7.23) in spleen cells from C, PF, and repleted mice and 11‐fold in T cells (P < 0.005), they remained below 1 in ID mice suggesting reduced translocation. In vitro iron chelation by deferoxamine for 120 min prior to cell activation reduced (P < 0.05) PKC activity by 46–60% in C and PF and 28–53% in ID mice. The data suggest that: 1) it is iron‐deficiency but not anemia or differences in the proportion of immunocompetent T cells that reduced PKC activity in cells from ID mice; 2) reduced PKC translocation may play an important role on altered lymphocyte proliferation and associated functions in iron‐deficient individuals. J. Cell. Biochem. 74:468–478, 1999.

Iron deficiency and in vitro iron chelation reduce the expression of cluster of differentiation molecule (CD)28 but not CD3 receptors on murine thymocytes and spleen cells.

Cluster of differentiation molecule (CD)3 and CD28 receptors play crucial roles in T-lymphocyte proliferation. Fe deficiency in man and animals impairs T-lymphocyte proliferation by unknown mechanisms. To test the hypothesis that reduced CD3 and CD28 expression is one of them, thymocytes and splenocytes from control (C; n 24), Fe-deficient (ID; n 24), pair-fed (PF; n 24), and ID mice that were Fe-repleted for 3 (R3; n 24) or 14 d (R14; n 12) were labelled with anti-CD3-fluorescein isothiocyanate and anti-CD28-phycoerythrin antibodies. Positive cells were analysed by flow cytometry. Significant differences were observed among groups in the mean levels of haemoglobin and liver Fe stores (C=PF=R14>R3>ID; P<0.005). While Fe deficiency slightly increased the percentage of CD3+ splenocytes, it reduced that of CD28+ thymocytes in mice with thymus atrophy and splenomegaly (P<0.05). These changes were corrected by Fe repletion. CD28 mean fluorescence intensity (FI) was lower and CD3 FI was higher in lymphocytes from R3 and ID, especially those with splenomegaly, than in those from R14 and PF mice (P<0.05). In vitro Fe chelation by deferoxamine (60 min) significantly decreased CD28 expression (P<0.05), and slightly increased that of CD3 (P>0.05). Spleen cell proliferative responses to concanavalin A and anti-CD3+/-anti-CD28 were reduced by Fe deficiency (ID</=R3<C=PF<R14; P<0.05); and they correlated with FI and percentages of CD3+ and CD28+ cells (r< or =0.69; P<0.05). Indicators of Fe status negatively correlated with CD3 FI (r-0.23), but positively correlated with CD28 FI (r< or =0.44; P<0.05). Data suggest that altered CD28 expression may contribute to reduced T-cell proliferation during Fe deficiency.

The Immune Response in Protein-Energy Malnutrition and Single Nutrient Deficiencies

Protein-energy malnutrition (PEM) (undernutrition or overnutrition) is one of the nutritional problems recognized by the WHO as public health problems in different parts of the world. The others are nutritional anemias, vitamin A deficiency, and iodine deficiency. Primary PEM (undernutrition) has long been regarded as a problem of underprivileged, low-socioeconomic groups, especially those from less developed countries. Although severe malnutrition (kwashiorkor and/or marasmus) are rare except in countries hit by natural disasters such as drought and war, mild and moderate malnutrition are quite common. The prevalence of this form of malnutrition varies from 21 to 70% depending on the continent and/or country (Rao and Naider, 1977; Suskind et al., 1990). This form of malnutrition may not be any less deleterious on the immune response than severe malnutrition, especially when it occurs in the context of poor sanitation, infections, and multiple nutritional deficiencies.

Iron deficiency reduces serum and in vitro secretion of interleukin-4 in mice independent of altered spleen cell proliferation.

Iron deficiency, a worldwide public health problem in children and adult women, impairs innate and cell-mediated immunity including interferon-γ secretion. Its effects on interleukin (IL)-4 have not been well investigated. Interleukin-4, a cytokine primarily secreted by TH2 lymphocytes, regulates B-cell proliferation and the switching of immunoglobulin (Ig)M to IgE subtypes; the latter is involved in the defense against helminth infection. Considering the fact that interferon-γ is a potent inhibitor of IL-4, we hypothesize that iron deficiency would increase the secretion of IL-4 and IgE. We measured IL-4 in serum and supernatant of concanavalin A and anti-CD3 antibody-treated spleen cells from iron-deficient, control, pair-fed DBA and C57BL/6 mice (20-24/group) and iron-replete mice for 3, 7, and 14 days (8-13/group). Feeding the low-iron diet (5 ppm vs 50 ppm for the control diet) for 2 months significantly reduced the mean levels of hemoglobin, hematocrit, liver iron stores, thymus weight, and induced splenomegaly in both strains of mice (P < .001). Iron deficiency, and not pair-feeding, reduced plasma IL-4 levels (P < .05), although it did not significantly affect IgE levels. Iron deficiency, especially when associated with thymus atrophy, reduced in vitro IL-4 secretion by activated spleen cells, cell proliferation, and percentage of CD4⁺IL-4⁺ cells (P < .05). Impaired cell proliferation did not fully explain reduced in vitro IL-4 secretion because iron-deficient mice with a normal thymus weight had a normal (3)H-thymidine uptake but decreased supernatant IL-4. It was likely due to low percentage of CD4⁺IL-4⁺. Iron repletion improved IL-4 measurements. Data suggest that iron deficiency has generalized negative effects on T-cell function. Unaltered plasma IgE may be due to other cytokines (ie, IL-13) that also modulate its secretion.

Reduced thymocyte proliferation but not increased apoptosis as a possible cause of thymus atrophy in iron-deficient mice.

Iron deficiency induces thymus atrophy in laboratory animals and very likely in humans by unknown mechanisms. The atrophy is associated with impaired cell-mediated immunity. In this study, we tested the hypothesis that thymus atrophy is a result of increased apoptosis and reduced thymocyte proliferation. Thymocytes were obtained from twenty-seven control, twenty-seven pairfed, twenty-seven iron-deficient (ID) mice; twelve and fourteen ID mice that received the control diet (0.9 mmol/kg versus 0.09 mmol/kg for the ID diet) for 1 d (repletion, R1) and 3 d (R3), respectively. Cell cycle analysis and apoptosis were studied by flow cytometry using propidium iodide staining and terminal deoxyuridine nick end labeling of DNA breaks assay respectively. When mice were killed, haemoglobin, haematocrit, and liver iron stores of ID, R1, and R3 mice were 25-40 % of those of control and pairfed mice Absolute and relative thymus weights and thymocyte numbers were 19 to 68 % lower in ID, R1, and R3 than in control and pairfed groups We found no significant difference among groups in the percentage of cells undergoing apoptosis. A higher percentage of thymocytes from ID and R1 mice than those of control, pairfed, and R3 mice were in the resting phase of the normal cell cycle Conversely, a lower percentage of thymocytes from ID and R1 mice than those from control, pairfed, and R3 mice were in the DNA synthesis phase and late phase of DNA synthesis and onset of mitosis (G2-M) Indicators of iron status positively correlated (r 0.3 to 0.56) with the percentage of thymocytes in the G2-M phase Results suggest that reduced cell proliferation but not increased apoptosis is the cause of thymus atrophy associated with iron deficiency.

Differential effects of iron deficiency on the expression of CD80 and CD86 co-stimulatory receptors in mitogen-treated and untreated murine spleen cells.

The interaction of CD28 and its ligands (CD80, CD86) on antigen presenting cells and that of TCR/CD3‐MHC are required for T lymphocyte activation. To determine whether impaired lymphocyte proliferation associated with iron deficiency is due to reduced expression of these ligands, spleen cells obtained from eight to nine C57BL/6 mice/group of iron deficient (ID), iron replete (R), control (C), pair‐fed (PF), and high iron (HI) mice were labeled with anti‐CD80‐fluorescein isothiocyante (FITC) and anti‐CD86‐FITC. Diets differed only in iron concentration: 5, 50, and 125 mg/kg for the ID, C, and HI, respectively. Mean levels of hemoglobin and liver iron stores of ID and R mice were less than 50% those of C mice (Pu2009<u20090.005). In non‐activated and concanavalin A‐treated cultures, significant differences were observed among groups in the percentage of CD80u2009+ cells: ID>Ru2009>u2009Cu2009=u2009PFu2009=u2009HI (Pu2009<u20090.05). The same trend was observed for CD86u2009+ cells (Pu2009>u20090.05). Fluorescence intensity (FI) of either marker did not significantly change by iron status. In vitro iron chelation by deferoxamine (20, 200 μg/ml) for 1, 2, and 24 h increased FI of both markers on unactivated B and T cells (Pu2009<u20090.05). However, it had no effect on FI of either marker of mitogen‐treated cells presumably because the maximum levels are achieved by the mitogen. Lymphocyte proliferative responses to mitogens positively and significantly correlated with CD80 and CD86 FI (ru2009=u20090.41−0.59) but negatively correlated with the percentages of CD80u2009+ cells (ru2009=u2009−0.48) (Pu2009<u20090.05). Data suggest that impaired lymphocyte proliferation associated with iron deficiency is not due to reduced CD80 and CD86 expression. J. Cell. Biochem. 86: 571–582, 2002.

Prevalence of Anaemia and Iron Deficiency in Urban Haïtian Children Two to Five Years of Age

This study was undertaken to assess the prevalence of anaemia and iron deficiency (ID) in 305 urban Haïtian children, 142 boys and 163 girls from low socioeconomic class, ranging in age from 2 to 5 years. Haemoglobin (Hb), serum ferritin (FERR), serum iron, total iron binding capacity (TIBC), transferrin saturation (TS), and red blood cell indices were measured by standard techniques. Although the means of these indices were within normal range, 58.4 per cent of children had at least one of the measurements in the abnormal range (FERR < 12 micrograms/l, TS < 12, HB < 10.7 g/l in 2 year old and < 10.9 g/dl in 3-5 year old children). The overall prevalence of anaemia (40 per cent) was slightly higher in boys (42 per cent) than in girls (36 per cent). Approximately 45 and 31 per cent of children had FERR < 12 micrograms/l TS < 12 per cent, respectively, with no difference between boys and girls. Despite the decrease in the prevalence of anaemia and ID with age, about one-third of the 5 year old children were either anaemic or iron deficient. Hypochromia and microcytosis were present in 60 and 66 per cent of children respectively. Although ID was the major cause of anaemia, protein-energy malnutrition as judged by low TIBC contributed to the high prevalence of anaemia. Megaloblastic anaemia and haemoglobinopathies did not significantly contribute to the high prevalence of anaemia. The frequency of fruit consumption, hence vitamin C, was lower in anaemic than non-anaemic children. We conclude that the eradication of anaemia and ID in this population will require improvement in overall nutritional status.

Effects of iron deficiency on the secretion of interleukin‐10 by mitogen‐activated and non‐activated murine spleen cells

Interleukin (IL)‐10 plays crucial regulatory roles in immune responses by inhibiting the secretion of several cytokines (IL‐2, IL‐12, interferon‐gamma (IFN‐γ)) and lymphocyte proliferation. Iron deficiency, a public health problem for children, alters these immune responses. To determine whether these changes are related to altered IL‐10 secretion, we measured IL‐10 in 24 and 48 h supernatant of spleen cell cultures from iron deficient (ID), control (C), pairfed (PF), and ID mice fed the control diet (iron repletion) for 3 (R3) and 14 (R14) days (d, nu2009=u200912/group). Mean levels of hemoglobin, hematocrit, and liver iron stores varied as follows: Cu2009≈u2009PFu2009≈u2009R14u2009>u2009R3u2009>u2009ID (Pu2009<u20090.01). Mean baseline IL‐10 levels of ID mice tended to be higher than those of other groups (Pu2009>u20090.05, ANOVA). Mean IL‐10 levels secreted by concanavalin A (Con A) and antibody raised against cluster of differentiation molecule 3 (anti‐CD3)‐treated cells (±background) were lower in ID than in C (48 h) and iron replete mice (Pu2009<u20090.05). Underfeeding also reduced IL‐10 secretion by anti‐CD3‐treated cells (48 h, Pu2009<u20090.05). Lymphocyte proliferative responses to anti‐CD3u2009±u2009anti‐CD28 antibodies were lower in ID than in C and PF mice, and they were corrected by iron repletion (Pu2009<u20090.05). IL‐10 levels negatively correlated with indicators of iron status (ru2009≤u2009−0.285) and lymphocyte proliferation (ru2009≤u2009−0.379 [ru2009≤u2009−0.743 for ID mice]), but positively correlated with IFN‐γ levels (ru2009≤u20090.47; Pu2009<u20090.05). Data suggest that iron deficiency has a generalized deleterious effect on cells that secrete both cytokines. Reduced IL‐10 secretion by activated cells does not overcome the inhibition of lymphocyte proliferation due to other factors of T cell activation that are regulated by iron. J. Cell. Biochem. 90: 278–286, 2003.

Differences in iron requirements by concanavalin A-treated and anti- CD3-treated murine splenic lymphocytes

Fe availability is critical for optimal lymphocyte proliferation; however, the minimum required levels are unknown. Such information is valuable when assessing in vitro immune responses in Fe-deficient subjects, because serum (Fe) added to the culture medium may replete lymphocytes. To address this issue, splenic lymphocytes obtained from seventeen 3-month-old C57BL/6 mice were incubated without and with 1 mg/l concanavalin A or 50 microg/l anti-CD3 antibody in media that contained between 0.113 and 9.74 micromol Fe/l. Fe was provided by either fetal calf serum (FCS, 0-100 ml/l), newborn calf serum (NBCS, 0-100 ml/l), or NBCS (10 ml/l) plus ferric ammonium citrate. As expected, the rate of DNA synthesis increased with Fe levels (P<0.01). Maximum DNA synthesis was obtained with 2.26 micromol Fe/l (50 ml FCS/l) for concanavalin A and 0.895 micromol/l (20 ml FCS/l) for anti-CD3-treated cells. In serum-free media (0.113 micromol Fe/l), the proliferative responses to concanavalin A were below the background, while they rose 5.5-fold in anti-CD3-treated cells (P<0.05). In apotransferrin-supplemented media (0.13 micromol Fe/l), the proliferative responses to concanavalin A and anti-CD3 antibody were 18.6 and 71 %, respectively, of that obtained with 4.66 micromol Fe/l (100 ml FCS/l). Interleukin 2 secretion also followed the same trend as lymphocyte proliferation. Since differences between both mitogens persisted after FCS was substituted with NBCS, we can rule out an effect on ribonucleotide reductase activity, or by other serum growth factors. We speculate an Fe effect at an early step of T-cell activation. Data suggest that the minimum Fe concentration required for lymphocyte proliferation varies with the mitogen.

Nutritional status of hemophiliacs with and without infection with the human immunoDeficiency virus (HIV)

Abstract We assessed the nutritional status of 42 hemophiliac children (22 months-18 years old), 20 with [HIV(+)] and 22 without [HIV(-)]a ntibodies to the human immunodeficiency virus (HIV). None had symptoms associated with acquired immunodeficiency syndrome (AIDS). Nutritional studies included anthropometry (Wt, Ht, Wt/Ht), hematology [Hb, WBC, absolute lymphocyte counts (ALC)] and biochemical measurements [Alb, prealbumin (PA), retinol-binding protein (RBP), transferrin (Tr), C-reactive protein (CRP) and alpha-1-acid-glycoprotein (AGP)]. A significantly higher percentage of HIV(+) (40%) than HIV(-) children (4.5%) were below the fifth percentile for their Ht (X 2 =5.495 p