Nutrition and AIDS

Therapeutic application of zinc in human immunodeficiency virus against opportunistic infections

The relevance of zinc in resistance to infections by virus, fungi and bacteria is recognized because of its pivotal role in the efficiency of the entire immune system, in particular in conferring biological activity to a thymic hormone called thymulin, which has differentiation properties on T-cell lines. In infection with human immunodeficiency virus (HIV), the zinc-bound form of thymulin (active thymulin, ZnFTS) is strongly reduced in stage IV of the disease (Centers for Disease Control and Prevention classification) with concomitant decrements in CD4(+) cell count and zincemia values. The zinc-unbound form of thymulin (inactive thymulin, FTS) is, in contrast, very high. The in vitro addition of zinc to plasma samples induces a recovery of the thymulin active form, suggesting low zinc bioavailability as the cause of impaired thymic functions with consequent CD4(+) depletion. An analysis of risk factors for the incidence of recidivism opportunistic infections shows CD4(+) depletion and zinc deficiency to have significant scores. Supplementation with zinc for 1 mo (45 mg Zn(2+)/d) associated with zidovudine (AZT) therapy in stage IV induces recovery of active zinc-bound thymulin, of zincemia, of CD4(+) cells with concomitant reduction (50%) of recidivism opportunistic infections compared with the AZT-treated group. Complete disappearance of recidivism by Candida aesophagea or Pneumocystis carinii is observed after supplementation with zinc. The relative risk factors (CD4(+) depletion and zinc-deficiency) have lower scores in the HIV-positive zinc-treated group, confirming, as such, the relevance of zinc in opportunistic infections that involve extracellular matrix. Such an assumption is indirectly confirmed with new HAART, where no opportunistic infections occur. Indeed, HIV RNA is inversely correlated with both CD4(+) and zincemia values (r = -0.73, P<0.01) in HAART-treated subjects. Lower scores for the same relative factors for the appearance of opportunistic infections are present in HAART-treated subjects compared with those treated with AZT. These findings, on the one hand, show the poor efficacy of AZT therapy compared with HAART therapy for the progression of HIV, but on the other hand, they suggest that the lack of occurrence of opportunistic infections by HAART may also result from major zinc bioavailability. This further supports the key role played by zinc against opportunistic infections in HIV with a possible independent effect by either HIV or the pathogens involved.

Threonine and methionine are limiting amino acids for protein synthesis in patients with AIDS

This study was conducted to identify the most rate-limiting amino acids for whole-body protein synthesis in acquired immunodeficiency syndrome (AIDS) patients. We postulated that an essential amino acid that would be rate limiting in AIDS should have a low basal plasma concentration and should remain at a low level during amino acid infusion. Seven male AIDS patients (median age 37 y, CD4 cell count: 76 mm-3) without any clinically active opportunistic infection during the month before the experiment were infused intravenously with a complete amino acid-glucose mixture for 2.5 h. Eight healthy volunteers were used as controls. Before the infusion, the concentrations of most free essential amino acids (methionine, threonine, histidine, isoleucine, leucine and tryptophan) were significantly lower (P < 0.05) in AIDS patients than in controls. Most plasma free essential amino acids increased significantly during infusion. However, the absolute increase above basal levels for threonine, valine, lysine, (P < 0.05) and methionine (P < 0.073) was smaller in AIDS patients than in control subjects. Thus, threonine and possibly methionine may be rate limiting for whole-body protein synthesis in AIDS patients, suggesting that there are selective amino acid requirements in patients with AIDS.

Home parenteral nutrition and AIDS

The evolution of AIDS in 25 patients enrolled in a home parenteral nutrition(HPN) programme was analysed retrospectively. All patients were grade 4C or 4D (CDC criteria). All suffered from major gastrointestinal symptoms, 13 had anorexia (< 700 kcal/day) and the overall mean weight loss was 21%. HPN involved administration of an all-in-one nutritional formula (caloric intake = 148% of MREE) which was infused at night through a Broviac type silastic catheter or a subcutaneous infusion port. It was continued until the patient's death or temporary recovery. 19 patients died during PN, 4 showed a temporary stabilisation. The average duration of PN was 180 days (54-358). Because of rehospitalizations for opportunistic infections or PN complications, the mean time spent at home was only 101 days (13-296), or 58.5% of the total duration of PN. 21 patients experienced weight gain and the Karnofsky activity index increased in half the patients. A temporary return to work was possible in only 3 patients. 15 PN related septicaemias were diagnosed for 4400 days of PN (0.34 for 100 days). On the whole, HPN seems to have been beneficial in 13 out of 25 patients, but the criteria for identifying patients who are likely to respond are not clearly established.

Nutritional support in HIV infection and AIDS

Weight loss and wasting are common features of HIV infection and AIDS. Patterns of weight loss can be acute or chronic which appear to be related primarily to systemic infections and gastrointestinal pathology, respectively. However, weight loss is not inevitable. and periods of weight stability and weight gain have been documented. Reduced food intake appears to be a major cause of weight loss in HIV infection. Since time of death has been associated with degree of wasting, it seems reasonable to suggest that nutritional support may contribute to enhancing survival and quality of life. All patients should have early access to a qualified dietitian such that assessment of individual situations can be made and appropriate dietary advice given, within a multi-disciplinary approach. Choice of nutritional therapy should be made based on an assessment of the causes of weight loss and an assessment of gut function. Treating infections and alleviating symptoms is vital for ensuring effective nutritional support. Enhancing the energy and protein density of foods and use of oral supplements should be considered if a normal diet alone cannot meet nutritional requirements. Unnecessary dietary restrictions should be avoided. Enteral feeding is indicated for patients unable to meet their needs via the oral route, and in cases of inadequate gut function, parenteral nutrition may be necessary. There is currently insufficient clinical evidence to justify the need for special enteral formulae specifically for patients with HIV infection.