Early and persistent bone marrow hematopoiesis defect in simian/human immunodeficiency virus-infected macaques despite efficient reduction of viremia by highly active antiretroviral therapy during primary infection

Abstract

The hematological abnormalities observed in human immunodeficiency virus (HIV)-infected patients appear to be mainly due to bone marrow dysfunction. A macaque models of AIDS could greatly facilitate an in vivo approach to the pathogenesis of such dysfunction. Here, we evaluated in this model the impact of infection with a pathogenic simian/human immunodeficiency virus (SHIV) on bone marrow hematopoiesis. Three groups of macaques were inoculated with 50 50% median infective doses of pathogenic SHIV 89.P, which expresses env of dual-tropic HIV type 1 (HIV-1) 89.6 primary isolate. During the primary phase of infection, animals were treated with either a placebo or highly active antiretroviral therapy (HAART) combining zidovudine, lamivudine, and indinavir, initiated 4 or 72 h postinfection (p.i.) and administered twice a day until day 28 p.i. In both placebo-treated and HAART-treated animals, bone marrow colony-forming cells (CFC) progressively decreased quite early, during the first month p.i. One year p.i., both placebo- and HAART-treated animals displayed decreases in CFC to about 56% of preinfection values. At the same time, a dramatic decrease (greater than 77%) of bone marrow CD34(+) long-term culture-initiating cells was noted in all animals were found. No statistically significant differences between placebo- and HAART-treated monkeys were found. These data argue for an early and profound alteration of myelopoiesis at the level of the most primitive CD34(+) progenitor cells during SHIV infection, independently of the level of viremia, circulating CD4(+) cell counts, or antiviral treatment.

FIG. 1

Evolution of total CFU numbers in cultures of bone marrow cells of macaques infected with SHIV 89.6P. (a) Placebo-treated macaques; (b) animals treated with HAART initiated 4 h p.i.; (c) animals treated with HAART initiated 72 h p.i. Diamonds, means of values for the different groups; error bars, SD; vertical arrow, end of treatment; dashed line, mean of more than 41 baseline values of noninfected, nontreated cynomolgus macaques.

FIG. 2

Plasma viremia and evolution of circulating CD4⁺ cells. (a) Plasma viral load estimated by the number of copies of viral RNA. (b) Numbers of CD4⁺ circulating T lymphocytes. Solid circles, placebo-treated macaques (means of three animals ± SD); squares, animals treated with HAART (means for four animals ± SD) between days 0 (4 h p.i.) and 28 p.i.; open circles, animals treated with HAART (means for four animals ± SD between days 3 and 28 p.i.. Vertical arrow, end of treatment period.

FIG. 3

Evolution of total CFU, BFU-E , CFU-GM, and CFU-M in cultures of bone marrow cells of noninfected, nontreated control macaque PR102B. This animal was subjected to sedation and blood and bone marrow collections with the same frequency as the other macaques.

FIG. 4

Evolution of BFU-E, CFU-GM, and CFU-M in cultures of bone marrow cells of macaques infected with SHIV 89.6P. (a) Placebo-treated macaques; (b) animals treated with HAART initiated 4 h p.i.; (c) animals treated with HAART initiated 72 h p.i. Means (diamonds) and SD (error bars) of values for the different groups are shown. Vertical arrow, end of treatment; dashed line, mean of more than 40 baseline values of noninfected, nontreated cynomolgus macaques.

FIG. 5

Evolution of LTC-IC obtained after 7 weeks of culture from immunopurified bone marrow (BM) CD34⁺ cells. (a) Numbers of red cell colonies; (b) numbers of white cell colonies; (c) total numbers of colonies. Shading of bars indicates the numbers of mononucleated cells seeded in culture (200, 100, 50, and 20).

FIG. 6

Comparison of 1-year-p.i. blood cell counts in the different groups of animals infected with SHIV. Tops and bottoms of boxes, 75th and 25th percentiles, respectively; horizontal lines between the box limits, medians; upper and lower error bars, 90th and 10th percentiles, respectively; circles, individual values outside the 90th and 10th percentiles. Before infection, 13 to 34 baseline values obtained before infection with SHIV 89.6P.