Malabsorption, malnutrition and HIV disease

The small intestine is a major target in HIV infection. Chronic diarrhoeal disease associated with malabsorption is the principal clinical manifestation of such infection. Reduced intestinal immunity and opportunistic enteric infections play a major role in clinical disease, but an enteropathy induced by HIV per se has also been implicated. The immunopathology of reduced intestinal immunity and its progression during HIV infection is poorly understood. HIV genome and proteins have been detected reproducibly in cells of the lamina propria resembling macrophages, but direct epithelial infection with HIV is controversial. Another factor which may contribute to diarrhoea is autonomic neuropathy within the jejunum. Small intestinal disease causes malabsorption of fat and disaccharides and may contribute to the weight loss seen in advancing HIV infection. However, malnutrition seen in HIV infection is multifactorial and may occur as a constitutional sign of infection in the absence of overt intestinal disease. Reduced food intake does not appear to be a causative factor in the weight loss in constitutionally well stage IV patients and there is some evidence that release of cytokines (TNF alpha/cachectin) into plasma or locally into tissue may mediate such events. The response of HIV-infected individuals to nutritional support is variable, but it is becoming increasingly apparent that the response is limited by the presence of severe systemic infection. However, aggressive nutrition is an important therapeutic mode which should be offered to all HIV-infected patients.