Efeitos da deficiência de cobre, zinco e magnésio sobre o sistema imune de crianças com desnutrição grave: [revisão] / Effects of copper, zinc and magnesium deficiency on the immune system of severely malnourished children: [review]

OBJETIVO: Esclarecer as repercussões da deficiência de cobre, zinco e magnésio sobre o sistema imune de crianças desnutridas graves. FONTES DE DADOS: Foi realizada revisão bibliográfica mediante consulta às bases de dados Pubmed Medline, Lilacs e SciELO, selecionando-se publicações científicas recentes, da última década, e representativas do tema por meio dos descritores: desnutrição infantil, cobre, zinco, magnésio e sistema imune. SÍNTESE DE DADOS: Os micronutrientes são compostos orgânicos essenciais. Além de sua função regulatória, atuam de maneira decisiva na modulação da resposta imune. Sua deficiência pode ocorrer devido à ingestão inadequada ou associada a doenças específicas. Quando associada à desnutrição, a multideficiência de minerais pode acarretar disfunções imunológicas e aumento na suscetibilidade a infecções, afetando gravemente a eficácia de intervenções terapêuticas. Cobre, zinco e magnésio atuam como cofatores de enzimas responsáveis tanto por diversas atividades metabólicas como na resposta imune inata e adquirida, além do papel importante na maturação dos tecidos e células linfoides. Sua deficiência acarreta neutropenia e linfopenia, comprometendo a imunocompetência. CONCLUSÕES: As alterações ocasionadas pelos déficits séricos dos minerais cobre, zinco e magnésio comprometem o funcionamento do sistema imune, levando à imunossupressão. A reposição desses elementos no manejo da desnutrição grave, como preconizada pela Organização Mundial da Saúde, é essencial, uma vez que tais alterações podem ser reversíveis.

OBJECTIVE: To report the effects of the deficiency of copper, zinc and magnesium on the immune system of severely malnourished children. DATA SOURCE: A literature review was performed by consulting the databases Pubmed Medline, Lilacs and SciELO, using the descriptors: child malnutrition, copper, zinc, magnesium and immune system. Representative studies published during the last decade were chosen. DATA SYNTHESIS: Micronutrients are essential organic compounds. Besides their regulatory function, the minerals act on the modulation of the immune response. Their deficiency may be due to inadequate intake or associated with specific diseases. When combined with malnutrition, a multimineral deficiency can cause immune dysfunction and increased susceptibility to infections, altering the effectiveness of therapeutic interventions. Copper, zinc and magnesium act as co-factors of both enzymes responsible for several metabolic activities and associated to the innate and acquired immune response. These minerals also play an important role in the maturation of lymphoid tissues and cells. Their deficiency causes neutropenia and lymphopenia, decreasing the immunocompetence. CONCLUSIONS: Deficits of serum copper, zinc and magnesium affect the function of the immune system, leading to immunosuppression. The replacement of these elements in the management of severe malnutrition, as recommended by the World Health Organization, is essential, since such changes may be reversible.

Increased production of tumor necrosis factor-alpha in whole blood cultures from children with primary malnutrition

Because low tumor necrosis factor-alpha (TNF-alpha) production has been reported in malnourished children, in contrast with high production of TNF-alpha in experimental protein-energy malnutrition, we reevaluated the production of TNF-alpha in whole blood cultures from children with primary malnutrition free from infection, and in healthy sex- and age-matched controls. Mononuclear cells in blood diluted 1:5 in endotoxin-free medium released TNF-alpha for 24 h. Spontaneously released TNF-alpha levels (mean ± SEM), as measured by enzyme immunoassay in the supernatants of unstimulated 24-h cultures, were 10,941 ± 2,591 pg/ml in children with malnutrition (N = 11) and 533 ± 267 pg/ml in controls (N = 18) (P < 0.0001). TNF-alpha production was increased by stimulation with lipopolysaccharide (LPS), with maximal production of 67,341 ± 16,580 pg/ml TNF-alpha in malnourished children and 25,198 ± 2,493 pg/ml in controls (P = 0.002). In control subjects, LPS dose-dependently induced TNF-alpha production, with maximal responses obtained at 2000 ng/ml. In contrast, malnourished patients produced significantly more TNF-alpha with 0.02-200 ng/ml LPS, responded maximally at a 10-fold lower LPS concentration (200 ng/ml), and presented high-dose inhibition at 2000 ng/ml. TNF-alpha production a) was significantly influenced by LPS concentration in control subjects, but not in malnourished children, who responded strongly to very low LPS concentrations, and b) presented a significant, negative correlation (r = -0.703, P = 0.023) between spontaneous release and the LPS concentration that elicited maximal responses in malnourished patients. These findings indicate that malnourished children are not deficient in TNF-alpha production, and suggest that their cells are primed for increased TNF-alpha production.

Hierro, infección y nutrición

El hierro cumple un papel esencial en el organismo como componente de moléculas encargadas del transporte y almacenamiento de oxígeno, sistemas de transferencia de electrones y diversas enzimas. La relación entre infección y utilización de hierro ha sido estudiada en los últimos años, en esta revisión se analizan los tópicos de más controversia al respecto: 1) la deficiencia crónica de hierro aumenta en el huésped la susceptibilidad a infección; 2) la deficiencia de hierro para su supervivencia, lo que se llama "inmunidad nutricional"; y 3) cuál es el comportamiento del hierro en el paciente críticamente enfermo.

Assessment of the immune and nutritional status of the host in childhood diarrhoea due to cryptosporidium.

Cryptosporidium oocysts were detected microscopically in the concentrated faecal smears (stained by modified kinyoun's acid fast stain) in 13 out of 100 (13 per cent) cases of acute diarrhoea (AD < 2 weeks duration), 7 out of 50 (14 per cent) cases of chronic diarrhoea (CD > 2 weeks duration) and none in 50 age matched controls. The grades of malnutrition of the cases and controls were calculated by the weight for age criteria and the immune status assessed by the levels of serum immunoglobulins and SIgA in duodenal fluids. Malnutrition was observed in 6 out of 13 cases (46.1 per cent) in acute and 6 out of 7 cases (85.71 per cent) in chronic cryptosporidial diarrhoeas. There was no significant statistical difference (P > 0.05) in serum immunoglobulins and SIgA levels in chronic cryptosporidiosis. SIgA was significantly reduced (P > 0.05) in cases of acute cryptosporidiosis. Cryptosporidium is an important cause of symptomatic infection in apparently immunocompetent children not having been detected in a single non-diarrhoeal control. Further a low SIgA could contribute to acute symptomatic cryptosporidiosis by favouring colonization with the parasite.

The transformation in vitro of peripheral lymphocytes of malnourished children.

Children with protein energy malnutrition showed high deranged cellular immunity as evidenced by impairment of lymphocyte transformation after stimulation by phytohaemagglutination (PHA). The proliferative response (PR) to PHA measured by estimating incorporation of tritiated thymidine into newly synthesized DNA. In-vitro proliferative response to PHA was used as a marker for studying the functional characteristics of T lymphocytes of children with different categories of malnutrition. PHA response of peripheral blood lymphocytes obtained from different categories of severely malnourished children were significantly low compared to healthy control children (P < 0.01). The results indicate that cell mediated immunity was grossly depressed in severe malnutrition.