Pre-existing malignancy results in increased prevalence of distinct populations of CD4+ T cells during sepsis

Abstract

The presence of pre-existing malignancy in murine hosts results in increased immune dysregulation and risk of mortality following a septic insult. Based on the known systemic immunologic changes that occur in cancer hosts, we hypothesized that the presence of pre-existing malignancy would result in phenotypic and functional changes in CD4+ T cell responses following sepsis. In order to conduct a non-biased, unsupervised analysis of phenotypic differences between CD4+ T cell compartments, cohorts of mice were injected with LLC1 tumor cells and tumors were allowed to grow for 3 weeks. These cancer hosts and age-matched non-cancer controls were then subjected to CLP. Splenocytes were harvested at 24h post CLP and flow cytometry and SPADE (Spanning-tree Progression Analysis of Density-normalized Events) were used to analyze populations of CD4+ cells most different between the two groups. Results indicated that relative to non-cancer controls, cancer mice contained more resting memory CD4+ T cells, more activated CD4+ effectors, and fewer naïve CD4+ T cells during sepsis, suggesting that the CD4+ T cell compartment in cancer septic hosts is one of increased activation and differentiation. Moreover, cancer septic animals exhibited expansion of two distinct subsets of CD4+ T cells relative to previously healthy septic controls. Specifically, we identified increases in both a PD-1hi population and a distinct 2B4hi BTLAhi LAG-3hi population in cancer septic animals. By combining phenotypic analysis of exhaustion markers with functional analysis of cytokine production, we found that PD-1+ CD4+ cells in cancer hosts failed to make any cytokines following CLP, while the 2B4+ PD-1lo cells in cancer mice secreted increased TNF during sepsis. In sum, the immunophenotypic landscape of cancer septic animals is characterized by both increased CD4+ T cell activation and exhaustion, findings that may underlie the observed increased mortality in mice with pre-existing malignancy following sepsis.

2B4 but not PD-1 blockade improves mortality in septic animals with preexisting malignancy

“…However, in animals with preexisting cancer, prevention of lymphocyte apoptosis by overexpression of Bcl-2 or using Bim -/mice lead to increased mortality in a pneumonia sepsis model (36). Moreover, we have previously shown that during sepsis, the dysregulated host response to infection may be exaggerated in animals with cancer compared with PH animals (37,38). Significantly increased activation markers (CD25, CD69) and coinhibitory receptors (PD-1, 2B4) expression were found on both CD4 + and CD8 + T cells.…”

“…response to sepsis in animals with cancer was characterized by increased activation and inflammation relative to that observed in healthy animals (37). Therefore, blockade of PD-1 may be insufficient to overcome the immune dysregulation in cancer septic animals and potentially may even further amplify the overwhelming inflammation during cancer sepsis.…”

Preexisting malignancy abrogates the beneficial effects of CXCR4 blockade during sepsis

“…Particularly, it has been reported that the ICU and in‐hospital mortality rates for cancer patients with sepsis were 42% and 56%, respectively, frequencies that are much higher than immunocompetent patients . While the etiology behind the increased mortality observed in septic cancer patients compared to previously healthy patients is multifactorial (and likely includes exposure to various anticancer drugs), we previously demonstrated that the presence of cancer (in the absence of any other treatment) negatively impacts the mortality following sepsis, and is associated with phenotypic and functional changes in CD4 + T cell responses following sepsis . Specifically, cancer mice contained more resting memory and activated CD4 + effector cells, exhibited increased frequencies of PD‐1 hi cells that failed to make any cytokines, and a distinct 2B4 hi BTLA hi LAG‐3 hi population that secreted more TNF compared to previously healthy (PH) septic controls.…”

“…6 While the etiology behind the increased mortality observed in septic cancer patients compared to previously healthy patients is multifactorial 7 (and likely includes exposure to various anticancer drugs), we previously demonstrated that the presence of cancer (in the absence of any other treatment) negatively impacts the mortality following sepsis, 8 and is associated with phenotypic and functional changes in CD4 + T cell responses following sepsis. 9 Specifically, cancer mice contained more resting memory and activated CD4 + effector cells, exhibited increased frequencies of PD-1 hi cells that failed to make any cytokines, and a distinct 2B4 hi BTLA hi LAG-3 hi population that secreted more TNF compared to previously healthy (PH) septic controls. This observed heterogeneity in co-inhibitory receptor expression and cytokine secretion The chemokine receptor CXCR4 and its ligand CXCL12 are involved in regulating the homeostatic recirculation and retention of myeloid and lymphoid cells in the bone marrow (BM).…”

Polymicrobial sepsis influences CD8 T cell responses and alters host susceptibility to infection and cancer

“…Flow cytometric data of tumor samples were manually gated on CD8 + cells using FlowJo software and exported to specifically analyze the CD8 TIL population. These individual files were uploaded to Cytobank (www.cytobank.org), a cloud-based computational platform, and input into SPADE algorithm, as described previously (234).…”