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Tracy Fischer-Smith, PhD

Assistant Professor, Neuroscience
Assistant Professor, Center for Neurovirology

Tracy Fischer-Smith
Contact Information

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About Me

Research Interests

Our laboratory is interested in how alterations in peripheral immune function impact the CNS. Previously, we identified that the macrophages that accumulate in the CNS of patients with HIV encephalitis (HIVE) are potentially skewed to a type 2 polarization, similar to that seen in T cell immunity in patients with AIDS. Recently, we observed expansion of a monocyte subset in the peripheral blood that may give rise to these macrophages in a single time point cross-sectional analysis of HIV infected patients. A positive correlation with the percent frequency of this monocyte subset and viral load and an inverse correlation with CD4+ T cells was also observed, suggesting a role for this monocyte subset in the development of AIDS. Interestingly, this monocyte subset is also expanded in aging and may have broader implications outside of the context of HIV infection. To increase our understanding of this expanded monocyte/macrophage subset and its role in the development and/or progression of CNS disease in HIV infection and aging, we are using a multidisciplinary approach that utilizes a number of investigative approaches to study these cells from human subjects.

In collaboration with Dr. Ellen Tedaldi, Director of the Temple Comprehensive HIV Program, we’re now expanding our previous study by following a cohort of HIV infected persons longitudinally. For these studies, anti-retroviral therapy (ART)-naïve patients are enrolled prior to the start of ART and followed for 2 years after the initiation of ART. We have studies designed to better understand the kinetics of the expansion of the expanded monocyte subset (that is CD163+/CD16+) with regard to viral load and CD4+ T cell count. We are also exploring the immune character of these cells to gain insights into their possible role in disease pathogenesis. In autopsy CNS tissue of patients with HIVE, cells with the same CD163+/CD16+ phenotype selected by laser capture microdissection are being investigated by microarray to better characterize their immune status and role in CNS disease. We’re hoping that these studies will help us better understand the nature of this expanded subset, how it functions in immune activation and how it might contribute to HIVE and AIDS pathogenesis for the identification of potential therapeutic targets.

As part of a larger project investigating the consequence of opioid use to the development of AIDS, our lab is responsible for the pathologic evaluation and characterization of CNS and visceral necropsy tissues from seronegative and SIV infected rhesus macaques. In collaboration with Dr. Tom Rogers, Dr. Jay Rappaport and Dr. Kamel Khalili, we are performing histological studies to explore the effect of opioids on immune modulation and disease progression in the context of HIV infection and AIDS, using SIVmac251-infected and morphine-treated Indian rhesus macaques.

Education, Training & Credentials

Educational Background

  • PhD, Biology, Temple University, 2005
  • Master of Music, Rider University, 1994
  • Bachelor of Music, Ohio Northern University, 1992


  • International Society for NeuroVirology (ISNV)
  • Society on Neuroimmune Pharmacology (SNIP)
  • American Society for Investigative Pathology (ASIP)

PubMed Publications

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