Macrophage dysfunction occurs late in sepsis and is implicated in increased mortality. Interferon γ (IFN-γ) stimulates transmigration of high mobility group box 1 (HMGB-1) from the nucleus into cytoplasm of macrophages and subsequent release. Because HMGB-1 release also occurs late, and because one of the actions of HMGB-1 in the nucleus is to enhance transcription factors, we investigated if HMGB-1 transmigration is involved in macrophage suppression in sepsis. Alveolar macrophages were isolated 12 and 24 h from sham controls, cecal ligation and puncture (CLP), and CLP rats given IFN-γ antibody (1.2 mg/kg, i.v.). All injections were given immediately after surgery. At 12 h, 60% of cells from sham controls had HMGB-1 located primarily in the nucleus, whereas 35% of cells had diffuse staining in both cytoplasm and nucleus. In CLP rats, HMGB-1 was located predominantly in the cytoplasm of 37% of cells, and 48% had diffuse staining, whereas in IFN-γ antibody (Ab)-treated rats, HMGB-1 was located predominantly in the nucleus of 56% of cells, whereas 32% had diffuse staining. At 24 h, most cells from CLP rats (82%) had HMGB-1 located in the cytoplasm, whereas in contrast, HMGB-1 was located in the nucleus of 80% and 82% of cells from sham control and IFN-γ Ab-treated rats, respectively. Gene expression of TNF-α was not significantly changed 12 h after surgery, but at 24 h, alveolar macrophages from CLP rats had reduced gene expression of TNF-α. Interferon γ Ab treatment prevented the reduction in TNF-α gene expression. TNF-α release was not altered at 12 h. At 24 h, LPS-stimulated release of TNF-α was decreased in macrophages from CLP rats compared with sham controls. Interferon γ Ab treatment prevented the decrease in LPS-stimulated TNF-α release. The results suggest that alveolar macrophage suppression after CLP is associated with HMGB-1 transmigration out of the cell nucleus and provides evidence that intranuclear HMGB-1 may play an integral role in macrophage activation in sepsis.
All Science Journal Classification (ASJC) codes
- Emergency Medicine
- Critical Care and Intensive Care Medicine