Don A. Baldwin

Natural SIV infection of sooty mangabeys (SMs) is nonprogressive despite chronic virus replication. Strikingly, it is characterized by low levels of immune activation, while pathogenic SIV infection of rhesus macaques (RMs) is associated with chronic immune activation. To elucidate the mechanisms underlying this intriguing phenotype, we used high-density oligonucleotide microarrays to longitudinally assess host gene expression in SIV-infected SMs and RMs. We found that acute SIV infection of SMs was consistently associated with a robust innate immune response, including widespread upregulation of IFN-stimulated genes (ISGs) in blood and lymph nodes. While SMs exhibited a rapid resolution of ISG expression and immune activation, both responses were observed chronically in RMs. Systems biology analysis indicated that expression of the lymphocyte inhibitory receptor LAG3, a marker of T cell exhaustion, correlated with immune activation in SIV-infected RMs but not SMs. Our findings suggest that active immune regulatory mechanisms, rather than intrinsically attenuated innate immune responses, underlie the low levels of immune activation characteristic of SMs chronically infected with SIV.

microRNAs (miRNAs) are small (approximately 22 nucleotide) regulatory RNAs which play fundamental roles in many biological processes. Recent studies have shown that the expression of many miRNAs is altered in various human tumors and some miRNAs may function as oncogenes or tumor suppressor genes. However, with the exception of glioblastoma multiforme, the expression of miRNAs in brain tumors is unknown. Furthermore, methods to profile miRNAs from formalin-fixed, paraffin-embedded (FFPE) archival tissues or to study their cellular and subcellular localization in FFPE tissues have been lacking. Here we report the coordinated miRNA expression analysis from the tissue level to the subcellular level, using the RAKE (RNA-primed, array-based, Klenow Enzyme) miRNA microarray platform in conjunction with Locked Nucleic Acid (LNA)-based in situ hybridization (LNA-ISH) on archival FFPE human brains and oligodendroglial tumors. The ability to profile miRNAs from archival tissues at the tissue level, by RAKE microarrays, and at the cellular level by LNA-ISH, will accelerate studies of miRNAs in human diseases.