Changes in the plasma proteome follows chronic opiate administration in simian immunodeficiency virus infected rhesus macaques

Abstract

Background: Substantive plasma proteomic changes follow lentiviral infection and disease pathobiology. We posit that such protein alterations are modified during drug abuse, further serving to affect the disease. To this end, we investigated the effect of opiate administration on the plasma proteome of Indian-strain rhesus monkeys infected with simian immunodeficiency virus (SIV) strain smm9.

Methods: Whole blood was collected at 7 weeks prior to and 1.4 and 49 weeks after viral infection. Viral load, CD4(+) T cell subsets, and plasma protein content were measured from monkeys that did or did not receive continuous opiate administrations. The plasma proteome was identified and quantified by isobaric tags for relative and absolute quantitation labeling (iTRAQ) and mass spectrometry.

Results: While substantive changes in plasma proteins were seen during SIV infection, the addition of opiates led to suppression of these changes as well as increased variance of the proteome. These changes demonstrate that opiates induce broad but variant immune suppression in SIV-infected monkeys.

Conclusion: The broad suppressive changes seen in plasma of SIV-infected monkeys likely reflect reduced multisystem immune homeostatic responses induced by opiates. Such occur as a consequence of complex cell-to-cell interactions operative between the virus and the host. We conclude that such changes in plasma proteomic profiling may be underappreciated and as such supports the need for improved clinical definitions.

Figure 1. Experimental design and timeline

(A) Timeline of blood collections, initiation of saline/opiate injections, and infection with SIVsmm9. (B) Experimental design and division of animals into groups.

Figure 2. iTRAQ Ratios and Western blot Validation

(A) iTRAQ ratios for selected proteins from monkeys infected with SIV only. (B) iTRAQ ratios for selected proteins from opiate treated monkeys infected with SIV. (C) Densitometry measurements for selected proteins from monkeys infected with SIV. (D) Densitometry measurements for selected proteins from opiate treated monkeys infected with SIV. (E) Averages of densitometry measurements performed in triplicate for each monkey infected with SIV. (F) Averages of densitometry measurements performed in triplicate for each opiate treated monkeys infected with SIV. Viral set points for each monkey are: RDE4 (HVSP), RKE4 (LVSP), RPD4 (LVSP), RPP3 (HVSP). HVSP = high viral set point; LVSP = low viral set point.

Figure 3. Comparison of Variability: Distribution of Differences in Standard Deviations

The distance each box is located from 0 is an indication of strength of significance. (A) Difference in standard deviation when comparing opiate treated monkeys versus saline treated monkeys at 3 different time points using Data Set I (114 proteins). (B) Difference in standard deviation when comparing opiate treated monkeys versus saline treated monkeys at three different time points using Data Set II (62 proteins). (C) Comparison of the standard deviation of abundances observed at different time points of the same treatment condition for Data Set I. (D) Comparison of the standard deviation of abundances observed at different time points of the same treatment condition for Data Set II.