Microbial exposure alters HIV-1-induced mucosal CD4+ T cell death pathways Ex vivo

Amanda K. Steele, Eric J. Lee, Jennifer Manuzak, Stephanie M. Dillon, John D. Beckham, Martin D. McCarter, Mario L. Santiago, Cara C. Wilson

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

Background: Early HIV-1 infection causes massive CD4+ T cell death in the gut and translocation of bacteria into the circulation. However, the programmed cell death (PCD) pathways used by HIV-1 to kill CD4+ T cells in the gut, and the impact of microbial exposure on T cell loss, remain unclear. Understanding mucosal HIV-1 triggered PCD could be advanced by an ex vivo system involving lamina propria mononuclear cells (LPMCs). We therefore modeled the interactions of gut LPMCs, CCR5-tropic HIV-1 and a commensal gut bacterial species, Escherichia coli. In this Lamina Propria Aggregate Culture (LPAC) model, LPMCs were infected with HIV-1BaL by spinoculation and cultured in the presence or absence of heat killed E.coli. CD4+ T cell numbers derived from flow cytometry and viable cell counts were reported relative to mock infection. Viable cells were identified by viability dye exclusion (AqVi), and intracellular HIV-1 Gag p24 protein was used to identify infected cells. Annexin V and AqVi were used to identify apoptotic versus necrotic cells. Caspase-1 and Caspase-3 activities were blocked using specific inhibitors YVAD and DEVD, respectively.Results: CD4+ T cell depletion following HIV-1 infection was reproducibly observed by 6 days post infection (dpi). Depletion at 6 dpi strongly correlated with infection frequency at 4 dpi, was significantly blocked by Efavirenz treatment, and was primarily driven by p24-negative cells that were predominantly necrotic. HIV-1 infection significantly induced CD4+ T-cell intrinsic Caspase-1 activity, whereas Caspase-1 inhibition, but not Caspase-3 inhibition, significantly blocked CD4+ T cell depletion. Exposure to E.coli enhanced HIV-1 infection and CD4+ T depletion, and significantly increased the number of apoptotic p24+ cells. Notably, CD4+ T cell depletion in the presence of E.coli was partially blocked by Caspase-3, but not by Caspase-1 inhibition.Conclusions: In the LPAC model, HIV-1 induced Caspase-1 mediated pyroptosis in bystander CD4+ T cells, but microbial exposure shifted the PCD mechanism toward apoptosis of productively infected T cells. These results suggest that mucosal CD4+ T cell death pathways may be altered in HIV-infected individuals after gut barrier function is compromised, with potential consequences for mucosal inflammation, viral dissemination and systemic immune activation.

Original languageEnglish (US)
Article number14
JournalRetrovirology
Volume11
Issue number1
DOIs
StatePublished - Feb 4 2014
Externally publishedYes

Fingerprint

HIV-1
Cell Death
T-Lymphocytes
Caspase 1
Mucous Membrane
HIV Infections
Caspase 3
Escherichia coli
Infection
efavirenz
Cell Count
HIV
gag Gene Products
Annexin A5
Flow Cytometry
Coloring Agents
Hot Temperature
Apoptosis
Inflammation
Bacteria

Keywords

  • Human Immunodeficiency Virus
  • Microbial translocation
  • Programmed cell death

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases

Cite this

Steele, A. K., Lee, E. J., Manuzak, J., Dillon, S. M., Beckham, J. D., McCarter, M. D., ... Wilson, C. C. (2014). Microbial exposure alters HIV-1-induced mucosal CD4+ T cell death pathways Ex vivo. Retrovirology, 11(1), [14]. https://doi.org/10.1186/1742-4690-11-14

Microbial exposure alters HIV-1-induced mucosal CD4+ T cell death pathways Ex vivo. / Steele, Amanda K.; Lee, Eric J.; Manuzak, Jennifer; Dillon, Stephanie M.; Beckham, John D.; McCarter, Martin D.; Santiago, Mario L.; Wilson, Cara C.

In: Retrovirology, Vol. 11, No. 1, 14, 04.02.2014.

Research output: Contribution to journalArticle

Steele, AK, Lee, EJ, Manuzak, J, Dillon, SM, Beckham, JD, McCarter, MD, Santiago, ML & Wilson, CC 2014, 'Microbial exposure alters HIV-1-induced mucosal CD4+ T cell death pathways Ex vivo', Retrovirology, vol. 11, no. 1, 14. https://doi.org/10.1186/1742-4690-11-14
Steele, Amanda K. ; Lee, Eric J. ; Manuzak, Jennifer ; Dillon, Stephanie M. ; Beckham, John D. ; McCarter, Martin D. ; Santiago, Mario L. ; Wilson, Cara C. / Microbial exposure alters HIV-1-induced mucosal CD4+ T cell death pathways Ex vivo. In: Retrovirology. 2014 ; Vol. 11, No. 1.
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KW - Human Immunodeficiency Virus

KW - Microbial translocation

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