Search

Abstract: Design: We evaluated whether an increase in haemoglobin levels in the first 6 months of effective anti-retroviral therapy (ART) is associated with a decrease in immune activation. To reduce confounding factors only men (n = 35) and patients not receiving agents known to enhance haematopoiesis or patients without diseases that might suppress haematopoiesis were included. Simultaneously parameters of iron metabolism and cofactors for haematopoiesis were analysed. Results: A median baseline haemoglobin level of 139 g L-1 increased to 149 g L-1 at month 6 of ART (P < 0.001). At baseline low haemoglobin levels were strongly associated with high neopterin concentrations (r = - 0.64, P < 0.001), and much less correlated to high HIV-1 RNA levels (r = - 0.41, P < 0.05) and to a lower CD4+ cell count (r = 0.33, P < 0.05). The change of neopterin levels during the study period correlated with the relative change in haemoglobin levels, r = - 0.35, P = 0.03, whereas no such correlations were found for the change of HIV-1 RNA levels and the CD4 cell count. A logistic regression analysis revealed that the change of neopterin and soluble transferrin receptors concentrations are independently associated with an increase of haemoglobin levels of more than 15 g L-1 . Conclusion: Our study supports a cause–effect relationship between immune activation and anaemia in HIV-infected patients. Treatment of patients with ART decreases virus load, which may thereby result in silencing of immune effector activity thus ameliorating anaemia by reversing the anti-proliferative effects of cytokines towards erythroid progenitors and the iron withdrawal strategy of the immune system. [ABSTRACT FROM AUTHOR]

We assessed the value of HIV–1 RNA level compared to soluble immune activation markers, namely neopterin, β[sub 2] –microglobulin and soluble TNF receptor 75 (sTNFR–75), to predict the change in the number of CD4+ T cells over a 1–year period, the development of AIDS, and survival (median follow–up 54 months). The study population comprised a cohort of 47 individuals for the analysis of the change in CD4+ T cells and survival (20 died), and a subgroup of 31 individuals with a baseline CD4+ T cells above 200×10[sup 6] /l for the development of AIDS (11 developed AIDS). HIV–1 RNA was measured from stored sera by quantitative PCR. The CD4+ T cell count obtained at study entry strongly correlated with baseline serum HIV–1 RNA levels (r = –0.47), and to a lesser extent with neopterin (r = –0.41) and β[sub 2] –microglobulin (r = –0.29). The percentage change in CD4+ T cells over a 1–year period correlated with HIV–1 RNA levels (r = –0.32, p = 0.03), however, stronger correlations were found for neopterin, β[sub 2] –microglobulin and sTNFR–75 (r = –0.51, r = –0.41, r = –0.42; p<0.01). No progression to AIDS or death was observed in individuals with baseline HIV–1 RNA levels below 20,000 copies/ml (10 of 31 and 15 of 47 individuals, respectively). A Cox’s proportional hazard model to predict AIDS revealed that HIV–1 RNA, the change in CD4+ cells over a 1–year period and sTNFR–75 levels independently predict AIDS; the change in CD4+ cells, the absolute CD4+ T cell count and neopterin were jointly significant to predict death. All results were adjusted for nucleoside monotherapy. In conclusion, to improve the predictive power, quantitation of HIV–1 RNA as a 'natural history marker’ may be supplemented by measurement of sTNFR–75 for 'early’–stage disease progression and neopterin for 'late’–stage disease progression. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Higher blood levels of the essential amino acid phenylalanine (phe) have been documented in patients with HIV-1 infection. They may relate to a diminished conversion of phe to tyrosine (tyr) by the enzyme phenylalanine-hydroxylase (PAH). PAH is rate-limiting in the biosynthesis of dopamine, and impaired PAH activity is reflected by an increased phe to tyr ratio (phe/tyr). Methods: Plasma phe/tyr was measured in 107 patients with HIV-1 infection before and after 12months of effective antiretroviral therapy (ART). Results were compared with CD4+ cell counts, HIV-1 RNA levels and concentrations of immune activation marker neopterin. Results: Before ART, phe/tyr was mean±S.D.: 0.99±0.57μmol/μmol. Phe/tyr correlated significantly with plasma and urine neopterin concentrations (rs =0.434, and rs =0.392; both p <0.001) and less strongly with HIV-RNA levels (rs =0.173) and CD4+ counts (rs =−0.182, both p <0.05). After ART, phe/tyr dropped to 0.72±0.16 (=−27%; U =5.21, p =0.01) which was due to an average decline of −14% of phe concentrations from 73.1±34.0μmol/L at baseline to 62.9±17.8μmol/L after ART (U =2.51, p =0.01) and a concomitant increase of tyr concentrations (+13%, U =2.46, p =0.01). In parallel, significant reductions of plasma and urine neopterin concentrations were observed during ART. Conclusions: Increased phe/tyr is frequent in patients with HIV-1 infection and is related to immune activation. ART was found to decrease phe/tyr and this change could indicate and influence on PAH activity. Future studies might be able to show whether the decline of phe/tyr under ART may concur with the often improved neuropsychiatric status in treated patients. [Copyright &y& Elsevier]

Antiretroviral therapy (ART) has a significant impact on HIV-1 RNA levels, the CD4 cell count, and immune activation. We examined whether these changes are associated with a change in the rate of tryptophan degradation (expressed as the kynurenine to tryptophan ratio, kyn/trp) as an estimate for the activity of interferon-γ inducible enzyme indoleamine (, )-dioxygenase (IDO). Plasma levels of tryptophan, kynurenine, and neopterin were measured pretherapy and 6 months postinitiation of therapy in 45 patients with HIV-1 RNA levels of less than 1000 copies/ml 6 months after initiation of ART. Before ART, the patients had decreased tryptophan and increased kynurenine concentrations compared to healthy controls. During ART, average tryptophan levels increased; in the same time kynurenine and kyn/trp decreased (P < 0.001), although not to normal levels. Since pretherapy tryptophan concentrations correlated inversely with neopterin, and kynurenine correlated with viral load and neopterin but not with CD4 cell count, the data support the view that HIV production may induce immune activation and consequently tryptophan is degraded at a higher rate. In agreement, kyn/trp positively correlated with neopterin (rs = 0.60, P < 0.001), with virus load (rs = 0.37, P = 0.013), and very weakly with CD4+ cells counts (rs = 0.30, P = 0.049). The change in the kyn/trp ratio during ART correlated more strongly with the change in neopterin levels (rs = 0.49, P = 0.001) than with the change in HIV RNA levels and weakly with the CD4 cell count. The data underscore the fact that both neopterin production and tryptophan degradation are triggered by immune activation. Tryptophan degradation is increased in HIV infection and partially reversed under ART. The data agree with the concept that immune activation is the common background of IDO activation which may be an important factor underlying T-cell hyporesponsiveness. [Copyright &y& Elsevier]