Murine Lung Cancer Increases CD4+ T Cell Apoptosis and Decreases Gut Proliferative Capacity in Sepsis.

BACKGROUND:Mortality is significantly higher in septic patients with cancer than in septic patients without a history of cancer. We have previously described a model of pancreatic cancer followed by sepsis from Pseudomonas aeruginosa pneumonia in which cancer septic mice have higher mortality than previously healthy septic mice, associated with increased gut epithelial apoptosis and decreased T cell apoptosis. The purpose of this study was to determine whether this represents a common host response by creating a new model in which both the type of cancer and the model of sepsis are altered. METHODS:C57Bl/6 mice received an injection of 250,000 cells of the lung cancer line LLC-1 into their right thigh and were followed three weeks for development of palpable tumors. Mice with cancer and mice without cancer were then subjected to cecal ligation and puncture and sacrificed 24 hours after the onset of sepsis or followed 7 days for survival. RESULTS:Cancer septic mice had a higher mortality than previously healthy septic mice (60% vs. 18%, p = 0.003). Cancer septic mice had decreased number and frequency of splenic CD4+ lymphocytes secondary to increased apoptosis without changes in splenic CD8+ numbers. Intestinal proliferation was also decreased in cancer septic mice. Cancer septic mice had a higher bacterial burden in the peritoneal cavity, but this was not associated with alterations in local cytokine, neutrophil or dendritic cell responses. Cancer septic mice had biochemical evidence of worsened renal function, but there was no histologic evidence of renal injury. CONCLUSIONS:Animals with cancer have a significantly higher mortality than previously healthy animals following sepsis. The potential mechanisms associated with this elevated mortality differ significantly based upon the model of cancer and sepsis utilized. While lymphocyte apoptosis and intestinal integrity are both altered by the combination of cancer and sepsis, the patterns of these alterations vary greatly depending on the models used

Alcohol delays the kinetics of CD69 expression of naïve CD4+ T cells and prolongs CD69 expression on memory CD4+ T cells.

<p>A) At 24h, CD69 expression increased in the water septic group over water sham (11.6±1% vs 8.6±0.6%, p = 0.01). At 72h, CD69 increased due to sepsis in both water and alcohol-fed groups (H2O sham 10.1±0.9% vs H2O CLP 19.9±1.4%, p = 0.04; EtOH sham 9.4±1% vs EtOH CLP 23.6±1.7%, p = 0.004). B) In naïve CD4s at 24h, the water septic group exhibited increase in CD69 expression (10.2±1.1% vs 5.6±1.0%, p = 0.04), while the alcohol fed group did not. By 72h, both alcohol and water fed groups exhibit CD69 upregulation in sepsis (H2O sham 4.4±0.5% vs H2O CLP 10.9±0.9%, p = 0.04; EtOH sham 4.3±0.4% vs EtOH CLP 13.2±0.5%, p = 0.005). C) In memory CD4s at 24h, sepsis increased CD69 in both water and alcohol-fed groups (H2O sham 18.7±0.8% vs H2O CLP 33.6±2.6%, p = 0.006; EtOH sham 23.5±0.9% vs EtOH CLP 36.4±0.8%, p = 0.03). At 72h, CD69 remained increased in alcohol septic mice only (EtOH sham 27.2±1.7% vs and EtOH sepsis 55.6±4%, p = 0.0003). n = 6-9/group.</p

IL-2 (but not IFN-γ or TNF) production by CD4+ T cells is decreased 72h following CLP in alcohol-fed animals.

<p>Representative flow plot and summary data 72h following sepsis, demonstrating a trend toward decreased IL-2 production due to alcohol alone between sham groups which did not reach significance, but there was a significant decrease in IL-2 in alcohol septic animals compared with water septic (16.15±1.7% vs 26.7±1.74%, p = 0.004). There were no differences in the frequencies of IFN-γ or TNF- producing CD4+ T cells between any of the groups. n = 7-12/group.</p

Alcohol decreases the frequency of CD8^dim cells in sepsis.

<p>A) Contour flow plot of the CD8^dim CD44^hi population of CD8+ T cells. B) At 72h after CLP, there is an increased frequency of CD8+ CD44^hi T cells with low expression of CD8 in water sepsis compared with alcohol sepsis (3.78±0.36% vs 2.71±0.07%, p = 0.01). n = 5-8/group.</p

CD4+ T cell frequencies and counts.

<p>A) Representative flow plots and gating strategy. B) There were no differences in CD4 frequencies or counts at 24h. C) At 72h, there were no relevant differences in CD4 frequency. A significant decrease in cell count was seen between alcohol sham and alcohol CLP (8.7x10⁷±1.3x10⁷ vs 4.1x10⁷±3.8x10⁶, p = 0.03). n = 6-9/group.</p

CD8+ T cell frequencies and counts.

<p>A) There were no relevant differences in CD8 frequencies or counts specifically due to sepsis or ethanol alone at 24h. B) At 72h, there was a strong trend toward a decrease in absolute count due to sepsis in both the water and alcohol fed groups. n = 6-9/group.</p