Iron deposition in liver in zidovudine-related transfusion-dependent anaemia

Iron and infection: effects of host iron status and the iron-regulatory genes haptoglobin and NRAMP1 (SLC11A1) on host-pathogen interactions in tuberculosis and HIV

There are many lines of evidence illustrating that iron plays a pivotal role in modulating the battle for survival between mammalian hosts and their pathogens. Each displays considerable genetic investment in a wide range of mechanisms for acquiring and maintaining iron. These competitive mechanisms are highly complex, existing within an interacting matrix of absorption, transport, storage and detoxification systems, each of which are iron-responsive and thus able to adapt to the different phases of infection. Considerable genetic polymorphism in some of these systems, with signals of geographic selection in the hosts, and niche selection in the pathogens, indicates that they are critical for species survival. In this review we briefly summarize the role of iron in host immune function before reviewing the available evidence that iron modulates susceptibility and disease outcomes in HIV and TB (tuberculosis). We then examine the putative role of iron-related host genes by focussing on two candidate genes, haptoglobin and NRAMP1, for which there are common polymorphic variants in humans with strong evidence of functionally distinct biochemical phenotypes that would be predicted to influence the course of HIV and TB infections. Finally, we examine the limited evidence so far available that nutrient-gene interactions are likely to influence the way in which gene variants can protect against infection. We conclude that there is a wealth of evidence associating alterations in iron balance and in iron-regulatory systems with disease progression, but that many issues related to the direction of causality, mechanisms of action and sensitivity to pharmacological intervention remain to be elucidated. Since iron is probably the most widely prescribed compound throughout the world, used in both preventative and treatment regimens, a deeper understanding of the host-pathogen interactions relating to iron constitutes an important area for both basic and clinical research.

Evidences that zidovudine (AZT) could not be directly responsible for iron overload in AZT-treated patients: an in vitro study

Zidovudine (3'-azido-3'-deoxythymidine or azidothymidine, AZT) has been the first antiretroviral agent approved for clinical use, and it is still currently used in combination therapy of human immunodeficency virus (HIV) infection. On the basis of increasing clinical reports and in vitro studies, a strict correlation between AZT treatment of HIV positive patients and both the development of anemia and iron overload have been in evidence over the last few years. In this report, we have examined some features of zidovudine to better assess a likely implication of this drug in iron overload. For this purpose, we first determinated the iron chelating ability of both AZT and some of its phosphorylated derivatives in solution. The iron chelating ability of AZT toward the intracellular 'chelatable' iron pool was also evaluated. Finally, we investigated the effect of AZT on both iron and transferrin uptake. Our findings indicate that AZT per se cannot be directly responsible for the development of the iron overload found in human or animal models, for which other possible mechanisms are claimed to be involved.

Iron overload in multiply transfused patients who are HIV seropositive

AIMS

To assess histologically the amount of iron deposited in liver biopsy specimens from HIV positive patients; and to perform estimations of liver iron on tissue from patients with an increase in parenchymal stainable iron. To correlate the amount of blood transfused and the degree of iron overload.

METHODS

Liver biopsy specimens (n = 120) from 109 HIV positive patients, 74 of whom had AIDS, were examined retrospectively and the amount of iron, as visualised with Perls's stain, was graded. Fibrosis was assessed using connective tissue stains. Estimations of liver iron were performed on tissue retrieved from paraffin wax blocks in cases with histological grade 3 or 4 iron overload. The amount of blood transfused before liver biopsy was determined from the notes for each patient.

RESULTS

Fifteen of the 120 liver biopsy specimens had significantly increased amounts of iron in their hepatocytes, as assessed histologically, and this was confirmed in seven cases by measurement of liver iron. There was a close correlation between the amount of blood transfused and the degree of iron overload. In the initial biopsy specimens only one case showed portal tract expansion. Three of the five patients who had repeat biopsies, however, showed progressive fibrosis.

CONCLUSION

Multiply transfused HIV positive patients may develop clinically important iron overload and are at risk of developing progressive fibrosis. Superimposed liver disease, especially viral hepatitis, in these high risk patients may exacerbate the effects of the iron overload.

Periportal fibrosis secondary to transfusion siderosis in two patients with acquired immune deficiency syndrome (AIDS) treated with zidovudine--a confusing ultrasound appearance

We present the confusing sonographic features of periportal fibrosis in two AIDS patients who had zidovudine-induced transfusion siderosis of the liver. To our knowledge this has not been previously reported in the literature. The clinical, pathological and sonographic features are described.

Surgical pathology of the liver in HIV infection

In the 6-year period 1984-1989, 101 liver biopsies or 'needle necropsies' from human immunodeficiency virus positive patients were examined histologically. Of these, only nine showed no abnormality whatsoever. The commonest histological findings were either fatty change or changes related to co-existent chronic viral hepatitis. Granulomas were seen in 15 cases, four of which were positive for acid-fast bacilli. A range of organisms were recorded: cytomegalovirus (4); Histoplasma capsulatum (1); Pneumocystis carinii (2); Cryptococcus neoformans (1); and Leishmania donovani (1). There were two cases of non-Hodgkin's lymphoma, but no cases of Kaposi's sarcoma. Marked iron deposition, which correlated with multiple blood transfusions was seen in nine biopsies. We were unable to identify any histological feature in the liver as being specific for HIV infection. The high incidence of liver abnormalities reflects: (i) the coincident exposure to hepatotropic viruses; (ii) the presence of opportunistic infections and neoplasms, usually part of a disseminated multi-organ process arising in the setting of profound immune depression; (iii) iatrogenic causes, in particular iron overload related to multiple blood transfusions received for treatment of zidovudine-induced anaemia; and (iv) non-specific changes associated with chronic debilitating disease.