Innate Immunity in HIV Infection: The expression and function of Toll Like Receptors

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Innate Immunity in HIV Infection The expression
and function of Toll Like Receptors

• Visvanathan K1, Skinner NA1, Lewin SR4 Wooley IJ
  Sasadeusz J.

Lab of Innate Immunity, Centre for Inflammatory
Diseases Monash University
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Bacterial Infections

• Infections with opportunistic pathogens have been
  one of the hallmarks of AIDS since the beginning
  of the epidemic
• bacterial pneumonia and bacteremia occur at a inc
  frequency among HIV-infected patients compared to
  age-matched controls.
• Bacterial infections were the leading cause of
  death in HIV-infected patients in Rhode Island
  over a two and half year period.
• One study of 46 autopsy cases found evidence of
  bacterial infection in 83

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• The course of certain bacterial infections does
  not differ -whereas other bacterial infections
  are notable for an increased incidence, a more
  fulminant course, invasive disease, and unusual
  rates of relapse.
• Evidence in mice that HIV impairs cytokine
  release alveolar macrophages

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Hypothesis

• HIV infection is associated with impaired
  macrophage TLR- mediated immune responses.

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The Innate Immune System

• Evolutionarily ancient
• Universal - all multicellular organisms
• Constitutive - germ-line
• Immediate pathogen response (hours)
• Components Pattern Recognition Central
• Pattern recognition receptors pathogen-assoc.
  molecular patterns
• Cell-surface eg Toll-like receptors
• Secreted
• Intracellular
• Phagocytes eg. dendritic cells
• Antimicrobial peptides eg. cathelicidins,
  defensins
• Alternate complement pathway

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LPS Signalling Pathway
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Patients and Methods

• Patients
• Whole blood (PBMC) on 25 stable patients 12
  CD4gt500 and 13 CD4lt200 and 15 normal controls
• Measured TLR2 and TLR4 expression on monocytes
  using flow
• Cells were also stimulated with specific TLR
  ligands and TNF-a and IL-6 were measured as well
  as phospho-MAP kinase

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Flow Cytometry for TLR2/4

• Isotype control Solid
• Normal Shaded
• HIV patient Open

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Elevated Expression of TLR2 and diminished
expression of TLR4 in HIV patients



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Stimulation of Whole Blood with TLR Ligands




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Stimulation of Whole Blood with TLR Ligands




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Phospho P38 Detection in CD14 Positive Cells as
Detected by Flow Cytometry
isotype
Control
LPS patient
Pam-3-Cys patient
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Phospho P38 Detection in CD14 Positive Cells as
Detected by Flow Cytometry


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Summary and Conclusion

• HIV infection seems to alter the expression of
  TLRs
• TLR2 is elevated
• TLR4 is downregulated
• LPS stimulation leads to decreased cytokine
  production and functional signalling
• Pam-3-Cys stimulation leads to increased cytokine
  production
• Potentially these changes in TLRs induced by the
  virus could cause increased responses to some
  (Gram ve) bacteria and decreased responses to
  others (Gram -ve)

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Future Directions

• Increased numbers - stratify for CD4
• Treatment Naïve patients
• Other TLRs
• Specific pathogens

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• Monash Innate Immunity Lab
• Narelle Skinner
• Vesna Markovska
• Ian Wooley

• Alfred
• Prof Sharon Lewin
• Joe Sasadeusz
• Mark Berezyni
• David Woolard

• VIDRL
• Prof Stephen Locarnini
• Tina Sozzi
• Ros Edwards