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Interleukin 6 (IL-6) is an inflammatory cytokine known to be elevated in chronic diseases and after insults such as trauma and infection. Although necessary for the development of B cells and Th17 cells, IL-6, at elevated levels, can also cause tissue damage and lead to a rise in inflammation. Previous work in our laboratory has shown that IL-6 is increased both systemically and in multiple organ systems including the ileum after ethanol exposure and burn injury. As this combined insult causes elevated intestinal morphological damage, tight junction protein localization alterations, and phosphorylated myosin light chain levels, we sought to determine the role of IL-6 in these intestinal responses using a model of binge ethanol exposure and burn injury. Interleukin 6 antibody treatment after the combined insult reduced morphological changes in the ileum, bacterial translocation, and phosphorylated myosin light chain levels relative to either injury alone. Zonula occludens protein 1 and occludin localization was also reestablished in wild-type mice given IL-6 antibody after ethanol and burn. Interleukin 6–knockout mice given ethanol and burn injury also had reduced intestinal damage; however, no changes in bacterial translocation or tight junction protein localization were observed as compared with similarly treated wild-type mice. These data suggest that IL-6 may have a role in intestinal tissue damage observed after the combined insult of binge ethanol exposure and burn injury, although complete loss of IL-6 does not seem to be beneficial in this model. Modulation of IL-6 may present a new option for preventing intestinal damage and associated inflammation after a combined insult of ethanol exposure and burn injury.

Combined radiation and burn injuries are likely to occur after nuclear events, such as a meltdown accident at a nuclear energy plant or a nuclear attack. Little is known about the mechanisms by which combined injuries result in higher mortality than by either insult alone, and few animal models exist for combined radiation and burn injury. Herein, the authors developed a murine model of radiation and scald burn injury. Mice were given a single dose of 0, 2, 4, 5, 6, or 9 Gray (Gy) alone, followed by a 15% TBSA scald burn. All mice receiving =4 Gy of radiation with burn survived combined injury. Higher doses of radiation (5, 6, and 9 Gy) followed by scald injury had a dose-dependent increase in mortality (34, 67, and 100%, respectively). Five Gy was determined to be the ideal dose to use in conjunction with burn injury for this model. There was a decrease in circulating white blood cells in burn, irradiated, and combined injury (5 Gy and burn) mice by 48 hours postinjury compared with sham (49.7, 11.6, and 57.3%, respectively). Circulating interleukin-6 and tumor necrosis factor-a were increased in combined injury at 48 hours postinjury compared with all other treatment groups. Prolonged overproduction of proinflammatory cytokines could contribute to subsequent organ damage. Decreased leukocytes might exacerbate immune impairment and susceptibility to infections. Future studies will determine whether there are long lasting consequences of this early proinflammatory response and extended decrease in leukocytes.

Background: Clinical and laboratory evidence suggests that alcohol consumption prior to burn injury leads to dysregulated immune function and subsequent higher rates of morbidity and mortality. Our laboratory previously observed higher levels of pro‐inflammatory cytokines and leukocyte infiltration in the lungs of mice following ethanol and burn injury. To understand the mechanism of the increased inflammatory response, we looked at different signaling initiators of inflammation including toll‐like receptors 2 and 4 (TLR2 and 4) pathways.

Clinical and laboratory evidence suggests that alcohol consumption dysregulates immune function. Burn patients who consume alcohol before their injuries demonstrate higher rates of morbidity and mortality, including acute respiratory distress syndrome, than patients without alcohol at the time of injury. Our laboratory observed higher levels of proinflammatory cytokines and leukocyte infiltration in the lungs of mice after ethanol exposure and burn injury than with either insult alone. To understand the mechanism of the increased pulmonary inflammatory response in mice treated with ethanol and burn injury, we investigated the role of intercellular adhesion molecule (ICAM)-1. Wild-type and ICAM-1 knockout (KO) mice were treated with vehicle or ethanol and subsequently given a sham or burn injury. Twenty-four hours postinjury, lungs were harvested and analyzed for indices of inflammation. Higher numbers of neutrophils were observed in the lungs of wild-type mice after burn and burn with ethanol treatment. This increase in pulmonary inflammatory cell accumulation was significantly lower in the KO mice. In addition, levels of KC, interleukin-1ß, and interleukin-6 in the lung were decreased in the ICAM-1 KO mice after ethanol exposure and burn injury. Interestingly, no differences were observed in serum or lung tissue content of soluble ICAM-1 24 hours postinjury. These data suggest that upregulation of adhesion molecules such as ICAM-1 on the vascular endothelium may play a critical role in the excessive inflammation seen after ethanol exposure and burn injury.

The purpose of this study was to determine whether 26S proteasome is detectable in human bronchoalveolar lavage fluid (BALF) and whether burn and inhalation injury is accompanied by changes in BALF proteasome content or activity. BALF was obtained on hospital admission from 28 patients with burn and inhalation injury (controls: 10 healthy volunteers). Proteasome concentrations were quantified by enzyme-linked immonosorbent assay, and their native molecular mass was assessed by gel filtration. Proteasome peptidase activity was measured using a chymotryptic-like peptide substrate in combination with epoxomicin (specific proteasome inhibitor). BALF protein was increased in patients (P< .001) and correlated positively with the degree of inhalation injury. The 20S/26S proteasomes were detectable in all BALF by enzyme-linked immonosorbent assay. Gel filtration confirmed the presence of intact 20S and 26S proteasome that was stable without soluble ATP/Mg2+. In all BALF chymotryptic-like activity was detectable and could be inhibited with epoxomicin by 60 to 70% (P< .01). Absolute amounts of 20S/26S proteasomes and proteasome activity were increased in patients (P< .001 for all). The relative BALF composition after injury was characterized by increased concentrations of 20S proteasome/mg protein (P= .0034 vs volunteers), decreased concentrations of 26S proteasome/mg protein (P= .041 vs volunteers), and reduced specific proteasome activity (P= .044 vs volunteers). The 26S proteasome per milligram and specific proteasome activity were even further reduced in patients who developed ventilator-associated pneumonia (P= .045 and P= .03 vs patients without ventilator-associated pneumonia). This study supports the novel concept that extracellular proteasomes could play a pathophysiological role in the injured lung and suggests that insufficient proteasome function may increase susceptibility for pulmonary complications.

Clinical and experimental evidence demonstrates that ethanol exposure prior to injury alters local and systemic inflammatory responses, increasing morbidity and mortality. Moreover, the aberrant inflammatory responses can directly and indirectly lead to the poor prognosis after injury by altering leukocyte infiltration into the wound site and remote organs and by suppressing immunity leading to increased susceptibility to opportunistic infections. Recent studies from our laboratory have focused on inflammatory responses at the wound site and in other distal organs after exposure to acute ethanol and burn injury. This combined insult leads to increased mortality after dermal or intratracheal pseudomonas infection, relative to infected mice given ethanol or burn injury alone. The increased mortality in mice given ethanol and burn injury parallels elevated serum levels of proinflammatory cytokines, IL‐6 and TNF‐α, marked infiltration of leukocytes into the lung and gut, as well as immunosuppression at the sites of infection. Bacterial translocation from the gut is likely to be responsible, in part, for the aberrant accumulation of leukocytes in the lungs of ethanol‐exposed, burn‐injured mice. Additionally, other factors, such as expression of adhesion molecules, increased chemokine production, and leakiness of the vascular endothelium, may also be involved.