Dissecting CMV-specific Immunity in High-Risk Lung Transplant Recipients: Differences between the Lung Allograft and Blood Effector T Cells

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Dissecting CMV-specific Immunity in High-Risk
Lung Transplant Recipients Differences between
the Lung Allograft and Blood Effector T Cells

• John F. McDyer, M.D.
• Assistant Professor of Medicine
• Johns Hopkins University
• February 1, 2008

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Disclosures
John F. McDyer, M.D.

• No Relevant Financial Relationships with
  Commercial Interests

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Goals

• CMV-specific T cell responses in high-risk lung
  transplant recipients
• Comparison of immune responses in the lung
  airways/allograft versus the blood
• Discuss a murine model of CMV (MCMV) pneumonitis
  in immunocompromised mice

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CMV and Lung Transplant

• Most common opportunistic infection in solid
  organ transplant, and lung transplant recipients
  (LTRs)
• ? Herpesvirus active acute infection and chronic
  infection
• Lung is a major reservoir for latent virus
  frequent primary activation of CMV in absence of
  immunity (DR-) LTRs

Primary CMV pneumonitis
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Primary CMV Significance

• The ability of high risk LTRs (DR- LTRS) to
  develop and maintain CMV-specific immunity may
  impact long-term allograft durability
• DR- status increased risk for 1- and 5-year
  mortality (2006 Registry of the International
  Society for Heart and Lung Transplant)
• Majority of studies evaluating risk factors for
  Bronchiolitis Obliterans Syndrome (chronic
  rejection) show CMV pneumonitis as a risk factor

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?Cross sectional study 65 of DR- LTRs have
detectable CMV-specific cellular and humoral
responses to CMV following primary
infection ?How are these responses acquired?

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Primary CMV LTR cohort
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BAL gt plasma viral loads during primary CMV
infection
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Primary CMV Cohort

• 9/15 probable or definite CMV pneumonitis (60)
  during primary infection
• 15/16 with primary CMV by 9 mos (94 vs. 39 in
  the literature for DR-)
• Current prospective DR- LTR cohort is 21
  patients, 5 on or just discontinued prophylaxis
  (3-4 months posttransplant)
• Total DR- post-primary CMV 33 LTRs

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Inversion of the BAL CD4CD8 ratio occurs
during primary CMV
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De novo CMV-specific CD8 effector T cells are
detectable in the PBMC during primary CMV
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De novo CMV-specific CD8 effector T cells are
detectable in the LMNC during primary CMV
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pp65-specific gt IE1-specific CD8 effector
responses in the lung airways predominate during
primary CMV
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CD8 gtCD4 pp65-specific effectors predominate
during primary CMV
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Assessment of Effector Quality

• Recent evidence has revealed a marked
  heterogeneity in the quality of memory T cell
  responses
• Polyfunctional cells appear to have better
  durability (multi-cytokine, cytolytic capacity)
• We observed a hierarchy of IFN-? gt TNF-? gt
  IL-2 cells CMV-specific CD8 T cells

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CMV-specific TNF-? CD8 Effectors demonstrate
higher co-expression of IFN-? (double positive)
compared to IFN-? cells with increased
frequencies in the lung airways
Mean LMNC 1.84 Mean PBMC 0.29 p 0.013
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IFN-? is quantitatively higher in double positive
CD8 effectors
p 0.03
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pp65-specific effector responses contract and
persist in the lung and blood
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CMV-specific CD8 effectors are CCR7- in the lung
and blood
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CD45 isoforms

• AKA leukocyte common antigen
• Expressed in various forms on all differentiated
  hematopoeitic cells except RBC plasma cells
• Alternative splicing leads to different isoforms
• Early dogma CD45RAnaïve, CD45ROmemory
• Recent work suggests that majority of
  CMV-specific effector memory cells are CD45RA
  (blood studies)

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CD45 isoforms in blood CD8 tetramer cells
changes from RO ? RA, but not in lung
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CD45 isoforms in blood CD8 IFN-? cells changes
from RO ? RA, but not in lung
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CMV-tetramer CD45RA cells revert to CD45RO
cells with proliferation
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Summary

• Quantitative viral load is higher in the lung
  allograft compared to the plasma during acute
  primary CMV
• Massive T cell influx into the lung allograft
  often occurs during primary CMV (CD8 T cells gt
  CD4 T cells) resulting in an inversion of the
  airway CD4CD8 T cell ratio.
• 3. De novo CMV-specific CD8 effector T cell
  responses (IFN-?) toward pp65gtIE1 are
  immunodominant in the lung airways/allograft
  during primary CMV

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Summary (contd)

• CMV-specific effector quality is higher in
• double positive (INF-?, TNF-?) CD8 T cells
• these cells are present at increased frequencies
  
• in the lung airways
• CMV-tetramer cells in PBMC shift from a
  CD45ROhigh
• phenotype during viremia to CD45RAhigh in
  clinical
• latent infection, but maintain a CD45ROhigh
  phenotype
• in airway memory cells, showing phenotypic
  differences
• in CD8 effector memory T cells between these
  tissues.
• 6. DR- LTRs provide a predictable human model
  of
• primary viral infection to assess the
  establishment
• of T cell memory at different tissue sites.

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Murine CMV (MCMV) pneumonitis model in BALB/c mice
Day 1 CY 200 mg/kg (i.p.)
Day 0 MCMV 105 PFU (i.n.)
D14
D7
lungs/spleens harvested both groups
D7
D14
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MCMV/CY mice develop pneumonitis pathology by day
14 p.i.
MCMV/CY
MCMV
CY
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MCMV/CY mice demonstrate higher pneumonitis
pathology scores
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MCMV/CY mice have a striking influx of CD8 T
cells at day 14
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CY treatment induces transient lymphopenia
followed by striking pulmonary CD8 T cell influx
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MCMV/CY mice have increased MCMV-specific CD8
effectors in lung
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pp89-specific CD8IFN-? effectors are increased
in the lungs of MCMV/CY mice during pneumonitis
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Lung MCMV viral titers are modestly higher in
MCMV/CY mice at day 14
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Summary

• Pneumonitis pathology in MCMV/CY mice is
  unexpectedly associated with increased,
  functional lung MCMV-specific CD8 effectors
• Further characterization of effector function is
  ongoing-major question is why more virus?
• Major hypothesis transient lymphopenia may
  provide space that allows a robust
  hyperexpansion of viral-specific effectors
  during primary infection
• This hypothesis will also be tested using
  adoptive transfer in Rag-1-/- mice vs. WT and
  tracking cells

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• Acknowledgements
• Matt Pipeling
• Pali Dedhiya
• Erin West
• Amanda Whitlock
• Johns Hopkins Lung Transplant Team
• NIAID,NIH Stephen Migueles, Mark Connors
• University of Oregon Ann B. Hill
• Funding support NHLBI and NIAID