The Role of Angiopoietin-2 in Post-Burn Pneumonia

Figures

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  Figure 1. Early elevation of Angiopoietin-2 and Ang-2/1 ratio in patient serum correlates with 30-day mortality. Burn patients were prospectively enrolled and serum was isolated and evaluated via ELISA for Angiopoietin-1 and 2. Dark blue dots represent patients who did not develop pneumonia within 30 days of burn, and red dots represent patients who did develop pneumonia within 30 days of burn. (A) Post-burn day 2 (PBD2) serum Ang-2 and (B) PBD2 Ang-2/1 ratio for patients that did not (−) and did (+) develop pneumonia within 30 days of injury ((A) p < 0.05, (B) p < 0.01). (C) Post-burn day 3 (PBD3) serum Ang-2 and (D) PBD3 Ang-2/1 ratio ((C) p < 0.0001, (D) p < 0.01). Significance was analyzed via Mann–Whitney U-test, ** p < 0.01, **** p < 0.0001, PBD2 (−) n = 21, (+) n = 10, PBD3 (−) n = 23, (+) n = 7.

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  Figure 2. Elevated plasma Angiopoietin-2 and downstream pulmonary mediators in a murine model of burn injury. Heparinized plasma was collected one day after burn or sham injury and evaluated for Ang-2 via ELISA. Dark blue dots represent mice that received sham injury, red dots represent mice that received burn injury. (A) Plasma Ang-2 was significantly increased in burn mice compared to sham. (B) Representative IHC of Ang-2 in sham and burn lungs. (C–H) Lung tissue was flash frozen one day after burn injury and then isolated for RNA, and RT-qPCR was performed with GAPDH as housekeeping control. (C) RT-qPCR expression of Tek, the transcript for the TIE2 receptor, was significantly elevated in burn lungs compared to sham (p < 0.01). (D) Tek expression positively correlated with plasma Ang-2 levels (simple-linear regression, R2 = 0.5655, p < 0.01). (E) Tnip2, the transcript of ABIN2, and (F) Pik3r1, a subunit of PI3K, were both significantly upregulated in the lungs following burn injury. (G) ICAM-1 and (H) VCAM-1 were also both significantly upregulated in the lungs following burn injury. For two-group analysis, significance was analyzed by unpaired t-test, n = 6–8 animals per group, ** p <…

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  Figure 3. Pulmonary neutrophil infiltration correlates with plasma Angiopoietin-2. Dark blue dots represent mice that received sham injury, red dots represent mice that received burn injury. (A) Representative H&E of lungs of sham and burn mice. (B) Neutrophils were counted in 6 high-powered fields in 3 mice each of sham and burn (p < 0.0001). (C) Lung RT-qPCR of chemokine Cxcl1 was elevated in burn compared to sham (p < 0.05) and (H) positively correlated with plasma Ang-2 (p < 0.01). (D–G) Neutrophil markers (D) Lcn2 (p < 0.01), (E) Ly6g (p = 0.0737), (F) s100a8 (p < 0.05), and (G) s100a9 (p < 0.05) were elevated in burn compared to sham and (I–L) all positively correlated with plasma Ang-2 levels (p < 0.05). For two-group analysis, significance was analyzed by unpaired t-test and correlation assessed by simple-linear regression, * p < 0.05, ** p < 0.01, **** p < 0.0001.