Vitamin A and human immunodeficiency virus infection

Evaluation of essential trace and toxic elements in biological samples of normal and night blindness children of age groups 3-7 and 8-12 years

The most common cause of blindness in developing countries is vitamin A deficiency. The World Health Organization estimates 13.8 million children to have some degree of visual loss related to vitamin A deficiency. The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence biological samples composition. Vitamin and mineral deficiency prevents more than two billion people from achieving their full intellectual and physical potential. This study was designed to compare the levels of Zn, Mg, Ca, K, Na, As, Cd, and Pb in scalp hair, blood, and urine of night blindness children age ranged 3-7 and 8-12 years of both genders, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of As, Ca, Cd, K, Pb, Mg, Na, and Zn in biological samples of night blindness children. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The concentrations of trace and toxic elements were measured by atomic absorption spectrophotometer prior to microwave-assisted acid digestion. The results of this study showed that the mean values of As, Cd, Na, and Pb were significantly higher in scalp hair, blood, and urine samples of male and female night blindness children than in referents (p < 0.001), whereas the concentrations of Zn, Ca, K, and Mg were lower in the scalp hair and blood but higher in the urine samples of night blindness children. These data present guidance to clinicians and other professional investigating deficiency of essential mineral elements in biological samples (scalp hair and blood) of night blindness children.

Evaluation of status of zinc, copper, and iron levels in biological samples of normal children and children with night blindness with age groups of 3-7 and 8-12 years

The causes of night blindness in children are multifactorial, and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition. This study was designed to compare the levels of zinc (Zn), copper (Cu), and iron (Fe) in scalp hair, blood, and urine of both genders of children with night blindness with age range of 3-7 and 8-12 years, comparing them to sex- and age-matched controls. A microwave-assisted wet acid digestion procedure was developed as a sample pretreatment, for the determination of zinc, copper, and iron in biological samples of children with night blindness. The proposed method was validated by using conventional wet digestion and certified reference samples of hair, blood, and urine. The digests of all biological samples were analyzed for Cu, Fe, and Zn by flame atomic absorption spectrometry using an air/acetylene flame. The results indicated significantly lower levels of Fe, Cu, and Zn in the biological samples (blood and scalp hair) of male and female children with night blindness, compared with control subjects of both genders. These data present guidance to clinicians and other professionals investigating the deficiency of essential trace metals in biological samples (scalp hair and blood) of children with night blindness.

SNP may modify the effect of vitamin A supplementation at birth on cytokine production in a whole blood culture assay

Within a neonatal vitamin A supplementation (VAS) trial, we investigated the effect of VAS on TNF-α, IL-10, IL-5 and IL-13 production after lipopolysaccharide, purified protein derivative (PPD) of Mycobacterium tuberculosis and phytohaemagglutinin stimulation using a whole blood culture protocol. We found that VAS recipients had lower unstimulated TNF-α concentrations than placebo recipients. In the present paper, we investigated whether the SNP TNF-α − 308, TNF-α − 238, IL-10 − 592, IL-10 − 1082 and toll-like receptor 4 (TLR4)+896 modified the effect of VAS on cytokine production. DNA and cytokine concentrations were available from 291 children. We found a significant interaction between TNF-α − 308 genotype and VAS for the unstimulated TNF-α production (Pinteraction = 0·04); among G homozygotes, TNF-α concentrations were significantly lower after VAS compared with placebo, whereas for A carriers, VAS did not appear to have any effect. For TNF-α − 238, there was a tendency towards an increase in PPD-stimulated TNF-α production after VAS for the G homozygotes, but the opposite tendency for A allele carriers (Pinteraction = 0·07). Stratification by sex revealed a significant VAS–genotype interaction for boys for TNF-α − 238. There was a borderline-significant three-way interaction (P = 0·05) between sex, VAS and TLR4+896 genotype. Although the present study had very limited representation of the genetic variation with potential for modification of the response to VAS, it adds to the efforts of untangling the diverse effects and impact of VAS.

Nutritional and immunological status and their associations among HIV-infected adults in Addis Ababa, Ethiopia

BACKGROUND

In the search for cost-effective interventions to reduce morbidity and mortality in HIV disease, the identification of nutritional status and levels of micronutrients is very important.

OBJECTIVE

To generate information on the level of energy malnutrition and on vitamin A, zinc, and hemoglobin levels and their relationships with disease status in HIV-infected adults in Addis Ababa, Ethiopia.

METHODS

A cross-sectional study was carried out on 153 HIV-positive adults (19% male, 81%female) living in Addis Ababa. The nutritional status and the levels of zinc, retinol, and hemoglobin were determined by anthropometric and biochemical methods. CD4+ counts and C-reactive protein levels were measured by standard methods.

RESULTS

Of the patients, 18% were chronically energy deficient, 71% were normal, and 11% were overweight. Serum zinc levels were low (< 10.7 micromol/L) in 53% of subjects, and serum retinol levels were low (< 30 microg/dL) in 47% of subjects. Low hemoglobin levels (< 12 g/dL) were observed in only 4.72% of the study population. CD4+ counts under 200/mm3 and elevated C-reactive protein levels were both found in 21% of the subjects. CD4+ counts were positively and significantly correlated with hemoglobin (r = 0.271, p < .001), zinc (r = 0.180, p < .033), and body mass index (r = 0.194, p < .017). There were significant negative associations between levels of C-reactive protein and levels of zinc (r = -0.178, p < 0.036 and hemoglobin (r = -0.253, p < .002).

CONCLUSIONS

Our results provide evidence that compromised nutritional and micronutrient status begins early in the course of HIV-1 infection. Low serum zinc and vitamin A levels were observed in almost half of the subjects. The clinical significance of low serum zinc and vitamin A levels is unclear, and more research is required.

Undernutrition, infection and immune function

Undernutrition and infection are the major causes of morbidity and mortality in the developing world. These two problems are interrelated. Undernutrition compromises barrier function, allowing easier access by pathogens, and compromises immune function, decreasing the ability of the host to eliminate pathogens once they enter the body. Thus, malnutrition predisposes to infections. Infections can alter nutritional status mediated by changes in dietary intake, absorption and nutrient requirements and losses of endogenous nutrients. Thus, the presence of infections can contribute to the malnourished state. The global burden of malnutrition and infectious disease is immense, especially amongst children. Childhood infections impair growth and development. There is a role for breast-feeding in protection against infections. Key nutrients required for an efficient immune response include vitamin A, Fe, Zn and Cu. There is some evidence that provision of the first three of these nutrients does improve immune function in undernourished children and can reduce the morbidity and mortality of some infectious diseases including measles, diarrhoeal disease and upper and lower respiratory tract infections. Not all studies, however, show benefit of single nutrient supplementation and this might be because the subjects studied have multiple nutrient deficiencies. The situation regarding Fe supplementation is particularly complex. In addition to immunization programmes and improvement of nutrient status, there are important roles for maternal education, improved hygiene and sanitation and increased supply of quality water in the eradication of infectious diseases.

Evaluation of essential and toxic metals by ultrasound-assisted acid leaching from scalp hair samples of children with macular degeneration patients

BACKGROUND

The causes of night blindness in children are multifactorial and particular consideration has been given to childhood nutritional deficiency, which is the most common problem found in underdeveloped countries. Such deficiency can result in physiological and pathological processes that in turn influence hair composition.

METHOD

An ultrasonic-assisted acid leaching procedure was developed as a sample pretreatment for the determination of Zn, Cu, Cd, As and Pb in human scalp hair samples of night blindness male children with age between 5 to 15 y and compared with the children without vision anomalies that lived in the same localities. The effects of different factors on acid leaching of metals, such as preintensification time (without ultrasonic stirring) after treatment of acid mixture, exposure time to ultrasound and temperature of the ultrasonic bath have been investigated. The proposed method was validated by certified reference samples of scalp hair CRM 397. The wet acid digestion method was used to obtain the total metal concentration in both scalp hair and CRM samples. Cu and Zn in leachates and digests were measured by flame atomic absorption spectrometry (FAAS) using a conventional air/acetylene flame, while Cd and Pb were determined by electrothermal atomic absorption spectrometry (ETAAS) under optimized conditions.

RESULTS

It was observed that at optimal conditions, the recovery for Zn, Cd, Pb, As and Cu were 98%, 98.5%, 96%, 97.2% and 94% respectively. The mean values of Zn and Cu in scalp hair samples of children having night blindness were significantly lower as compared to normal healthy children (p for Zn<0.001 and Cu<0.003), while the level of toxic metals As, Cd and Pb were significantly higher in children having ocular problems as related to normal children (p As<0.0074, Cd<0.001 and lead<0.004).

CONCLUSION

These data present guidance to clinicians and other professional investigating deficiency of essential trace metals and excessive level of toxic metals in biological samples.

Effect of periodic vitamin A supplementation on mortality and morbidity of human immunodeficiency virus-infected children in Uganda: A controlled clinical trial

OBJECTIVE

We investigated whether vitamin A supplementation would decrease mortality and morbidity rates in children infected with the human immunodeficiency virus (HIV).

METHODS

We conducted a randomized, double-blind, placebo-controlled clinical trial at Mulago Hospital, a large hospital that serves the urban and semiurban populations of Kampala, Uganda. One hundred eighty-one HIV-infected children were enrolled at 6 mo and randomized to receive vitamin A supplementation, 60 mg retinol equivalent, or placebo every 3 mo from ages 15 to 36 mo. Morbidity was assessed through a 7-d morbidity history every 3 mo, and vital events were measured. Children received daily trimethoprim-sulfamethoxazole prophylactic therapy.

RESULTS

After age 15 mo, children were followed for a median of 17.8 mo (interquartile range = 11.1 to 21.0 mo). The trial was stopped when there was a new policy to implement a program of mass supplementation of vitamin A in the country. Mortality rates among 87 children in the vitamin A group and 94 children in the control group were 20.6% and 32.9%, respectively, yielding a relative risk of 0.54 (95% confidence interval, 0.30 to 0.98; P = 0.044) after adjusting for baseline weight-for-height Z score. Children who received vitamin A had lower modified point prevalences of persistent cough (odds ratio, 0.47; 95% confidence interval, 0.23 to 0.96; P = 0.038) and chronic diarrhea (odds ratio, 0.48; 95% confidence interval, 0.19 to 1.18; P = 0.11) and a shorter duration of ear discharge (P = 0.03). Vitamin A supplementation had no significant effect on modified point prevalences of fever, ear discharge, bloody stools, or hospitalizations.

CONCLUSIONS

Vitamin A supplementation decreases mortality rate in HIV-infected children and should be considered in the care for these children in developing countries.

Complementary and alternative medicine: assessing the evidence for immunological benefits

With words such as AIDS, allergy and autoimmunity embedded in the popular lexicon, we often equate health with the precision and the tenor of responses to allergens and microorganisms. This leads many people to seek their own solutions to sustain, restore or even boost their immune competence, hoping to live more comfortably and longer. Here, we consider the social and clinical contexts in which these promises of enhanced immunity are pursued through popular practices known as complementary and alternative medicine and the evidence that supports these.

Plasma vitamin A and zinc levels in HIV-infected adults in Cape Town, South Africa

A cross-sectional study of 132 adults attending an HIV clinic in Cape Town, South Africa, was conducted to determine predictors of low plasma vitamin A and Zn levels. No patients were on antiretroviral therapy. The possible confounding effect of the acute-phase response was controlled by including C-reactive protein levels in multivariate analysis and by excluding active opportunistic infections. Retinol levels were low (<1.05 micromol/l) in 39 % of patients with early disease (WHO clinical stages I and II) compared with 48 and 79 % of patients with WHO stage III and IV respectively (P<0.01). Plasma Zn levels were low (<10.7 micromol/l) in 20 % of patients with early disease v. 36 and 45 % with stage III and IV disease respectively (P<0.05). C-reactive protein levels were normal in 63 % of subjects. Weak, positive associations were found between CD4+ lymphocyte count and plasma levels of retinol (r 0.27; 95 % CI 0.1, 0.43) and Zn (r 0.31; 95 % CI 0.25, 0.46). Multivariate analysis showed the following independent predictors of low retinol levels: WHO stage IV (odds ratio 3.4; 95 % CI 2.1, 5.7) and body weight (odds ratio per 5 kg decrease 1.15; 95 % CI, 1.08, 1.25), while only body weight was significantly associated with low Zn levels (OR per 5 kg decrease 1.19; 95 % CI 1.09, 1.30). CD4+ lymphocyte count <200/microl was not significantly associated with either low retinol or Zn levels. In resource-poor settings, simple clinical features (advanced disease and/or weight loss) are associated with lowered blood concentrations of vitamin A and/or Zn. The clinical significance of low plasma retinol and/or Zn levels is unclear and more research is required to establish the role of multiple micronutrient intervention strategies in HIV disease.

Retinoic acid enhances the T helper 2 cell development that is essential for robust antibody responses through its action on antigen-presenting cells

Previously we reported that vitamin A-deficient (-A) mice had a profound reduction in T helper 2 (Th2) cells, accounting for their depressed T-dependent antibody responses. Providing vitamin A or its active metabolites reversed this defect. The current experiments utilized splenocytes from T cell receptor transgenic mice to investigate how all-trans retinoic acid (atRA) augments Th2 development. These cells were stimulated in vitro in the presence or absence of atRA, with or without exogenous cytokines driving Th1 or Th2 development. Without exogenous cytokines, atRA addition significantly inhibited the interferon (IFN)-gamma response but did not alter the interleukin (IL)-4 response. With Th1 polarizing cytokines, atRA enhanced the IFN-gamma response, with no effect on the IL-4 response. Most importantly, with the Th2 polarizing cytokine IL-4, atRA significantly increased the IL-4 secretion (fivefold) and also increased the Th2 cell frequency twofold. The striking Th2 enhancement was also observed when only antigen-presenting cells were treated with atRA before stimulation of untreated CD4(+) transgenic T cells, but not vice versa. Thus, atRA maximized Th2 cell development in an IL-4-dependent manner, through an effect on antigen-presenting cell function.

Vitamin A, infection, and immune function

In populations where vitamin A availability from food is low, infectious diseases can precipitate vitamin A deficiency by decreasing intake, decreasing absorption, and increasing excretion. Infectious diseases that induce the acute-phase response also impair the assessment of vitamin A status by transiently depressing serum retinol concentrations. Vitamin A deficiency impairs innate immunity by impeding normal regeneration of mucosal barriers damaged by infection, and by diminishing the function of neutrophils, macrophages, and natural killer cells. Vitamin A is also required for adaptive immunity and plays a role in the development of T both-helper (Th) cells and B-cells. In particular, vitamin A deficiency diminishes antibody-mediated responses directed by Th2 cells, although some aspects of Th1-mediated immunity are also diminished. These changes in mucosal epithelial regeneration and immune function presumably account for the increased mortality seen in vitamin A-deficient infants, young children, and pregnant women in many areas of the world today.

Impaired bioavailability of vitamin A in adults and children with persistent diarrhoea in Zambia

BACKGROUND

We have previously demonstrated a strong relationship between low serum retinol concentration and mortality in Zambian AIDS patients with diarrhoea, but were unable to detect any benefit from oral micronutrient supplementation.

AIM

To test the hypothesis that this is related to impaired availability of vitamin A, we analysed serum retinol concentration changes over 6 h following oral mega-dose therapy (60, 120 or 180 mg retinol).

METHODS

Twenty-four men without diarrhoea, 15 adults with persistent diarrhoea and 11 children (six girls, five boys) with persistent diarrhoea were studied.

RESULTS

Men with persistent diarrhoea had lower baseline serum retinol concentrations (median 0.39 micromol/L, interquartile range 0.21-0.56) than controls (median 1.16 micromol/L, interquartile range 0.84-1.47; P=0.0003). After 60 mg retinol, the rise in serum retinol in HIV seropositive controls (median 0.63 micromol/L, interquartile range 0.35-0.77) did not differ significantly from that observed in HIV seronegative controls (median 0.35 micromol/L, interquartile range - 0.04-0.56; P=0.20). Increasing the dose to 120 mg or 180 mg retinol did not enhance the increase in serum retinol concentration. The increase in serum retinol was less in adults with persistent diarrhoea (median 0.25 micromol/L, interquartile range 0.04-0.35) and in children (median 0.11 micromol/L, interquartile range 0.04-0.46) than in men without diarrhoea (median 0.44 micromol/L, interquartile range 0.26-0.74; P=0.03). Adults and children with diarrhoea had greater losses of retinol in urine over a 24-h period than controls, but less than 1% of the ingested dose was excreted.

CONCLUSIONS

These results suggest that persistent diarrhoea in this population is associated with reduced bioavailability of retinol. Further work is required to determine the metabolic fate of therapeutic doses of retinol and to determine appropriate replacement strategies for HIV infected individuals.

Low carotenoid concentration and the risk of HIV seroconversion in Pune, India

Low vitamin A and carotenoid levels could increase the risk of sexual HIV acquisition by altering the integrity of the genital epithelium or by immunologic dysfunction. We addressed this issue by measuring serum vitamin A and carotenoid levels in patients who were at risk of subsequent HIV infection. In a nested case-control study in individuals attending two sexually transmitted disease (STD) clinics in Pune, India, serum micronutrient levels were measured in 44 cases with documented HIV seroconversion (11 women and 33 men) and in STD patients matched for gender and length of follow-up with no subsequent HIV seroconversion (controls). STD patients in Pune had low vitamin A and carotenoid levels, and low serum beta-carotene levels were independently associated with an increased risk of subsequent HIV seroconversion. STD patients with beta-carotene levels less than 0.075 micromol/L were 21 times more likely to acquire HIV infection than those with higher levels (adjusted odds ratio = 21.1; p =.01). No such association was observed in case of other non-provitamin A carotenoids. This study reports the first evidence of an association between low serum provitamin A carotenoid levels and an increased risk for heterosexual HIV acquisition in STD patients in Pune, India.

Micronutrient supplementation in the AIDS diarrhoea-wasting syndrome in Zambia: a randomized controlled trial

OBJECTIVE

As HIV has spread through sub-Saharan Africa, persistent diarrhoea has emerged as a major problem in hospitals and in the community in severely affected areas. We have previously demonstrated that antiprotozoal therapy with albendazole reduces diarrhoea in AIDS patients in urban Zambia. This trial was designed to test the hypothesis that the clinical response to albendazole might be improved by oral micronutrient supplementation.

DESIGN

Randomized, placebo-controlled trial.

SETTING

Home care service of Ndola Central Hospital, Zambia.

PATIENTS

HIV-seropositive patients with persistent diarrhoea.

INTERVENTION

Patients were randomized to albendazole plus vitamins A, C and E, selenium and zinc orally or albendazole plus placebo, for 2 weeks.

MAIN OUTCOME MEASURES

Time with diarrhoea following completion of treatment; mortality; adverse events.

RESULTS

Serum vitamin A and E concentrations before treatment were powerful predictors of early mortality, but supplementation did not reduce time with diarrhoea or mortality during the first month, even after taking into account initial vitamin A or E concentrations, CD4 cell count or clinical markers of illness severity. Serum concentrations of vitamins A and E did not increase significantly in supplemented patients compared with those given placebo, and there were no changes in CD4 cell count or haematological parameters. No adverse events were detected except those attributable to underlying disease.

CONCLUSIONS

Although micronutrient deficiency is predictive of early death in Zambian patients with the diarrhoea-wasting syndrome, short-term oral supplementation does not overcome it nor influence morbidity or mortality.

Micronutrients and the pathogenesis of human immunodeficiency virus infection

Micronutrient deficiencies may be common during human immunodeficiency virus (HIV) infection. Insufficient dietary intake, malabsorption, diarrhoea, and impaired storage and altered metabolism of micronutrients can contribute to the development of micronutrient deficiencies. Low plasma or serum levels of vitamins A, E, B6, B12 and C, carotenoids, Se, and Zn are common in many HIV-infected populations. Micronutrient deficiencies may contribute to the pathogenesis of HIV infection through increased oxidative stress and compromised immunity. Low levels or intakes of micronutrients such as vitamins A, E, B6 and B12, Zn and Se have been associated with adverse clinical outcomes during HIV infection, and new studies are emerging which suggest that micronutrient supplementation may help reduce morbidity and mortality during HIV infection.

HIV: mother to child transmission, current knowledge and on-going studies

It is estimated that approximately 6000 women of childbearing age, mostly living in the developing world, acquire HIV infection every day. Taking into account that approximately 98% of HIV infected children have acquired HIV from the mother, during pregnancy, at delivery or through breastfeeding, therefore, prevention of mother-to-child transmission (MTCT) is a major health priority. Several studies have showed how MTCT of HIV may be prevented using antiretrovirals. Results from a study conducted in Thailand have also recently showed how a short oral zidovudine course during pregnancy and labor may reduce the risk of HIV transmission by approximately 50%. These findings represent a major challenge for the International Health Agencies and Organizations that will have the major obligation to provide HIV tests, counseling and antiviral drugs in settings with high HIV prevalence.