by
Enjae Jung;
Erin E. Perrone;
Pavan Brahmamdan;
Jacquelyn S. McDonough;
Ann M. Leathersich;
Jessica A. Dominguez;
Andrew T. Clark;
Amy C. Fox;
W. Michael Dunne;
Richard S. Hotchkiss;
Craig Coopersmith
World conditions place large populations at risk from ionizing radiation (IR) from detonation of dirty bombs or nuclear devices. In a subgroup of patients, ionizing radiation exposure would be followed by a secondary infection. The effects of radiation combined injury are potentially more lethal than either insult in isolation. The purpose of this study was to determine mechanisms of mortality and possible therapeutic targets in radiation combined injury. Mice were exposed to IR with 2.5 Gray (Gy) followed four days later by intratracheal methicillin-resistant Staphylococcus aureus (MRSA). While either IR or MRSA alone yielded 100% survival, animals with radiation combined injury had 53% survival (p = 0.01). Compared to IR or MRSA alone, mice with radiation combined injury had increased gut apoptosis, local and systemic bacterial burden, decreased splenic CD4 T cells, CD8 T cells, B cells, NK cells, and dendritic cells, and increased BAL and systemic IL-6 and G-CSF. In contrast, radiation combined injury did not alter lymphocyte apoptosis, pulmonary injury, or intestinal proliferation compared to IR or MRSA alone. In light of the synergistic increase in gut apoptosis following radiation combined injury, transgenic mice that overexpress Bcl-2 in their intestine and wild type mice were subjected to IR followed by MRSA. Bcl-2 mice had decreased gut apoptosis and improved survival compared to WT mice (92% vs. 42%; p<0.01). These data demonstrate that radiation combined injury results in significantly higher mortality than could be predicted based upon either IR or MRSA infection alone, and that preventing gut apoptosis may be a potential therapeutic target.
Background: The gut is hypothesized to be the "motor" of critical illness. Under basal conditions, the gut plays a crucial role in the maintenance of health. However, in critical illness, all elements of the gut are injured, potentially worsening multiple organ dysfunction syndrome. Main body: Under basal conditions, the intestinal epithelium absorbs nutrients and plays a critical role as the first-line protection against pathogenic microbes and as the central coordinator of mucosal immunity. In contrast, each element of the gut is impacted in critical illness. In the epithelium, apoptosis increases, proliferation decreases, and migration slows. In addition, gut barrier function is worsened via alterations to the tight junction, resulting in intestinal hyperpermeability. This is associated with damage to the mucus that separates the contents of the intestinal lumen from the epithelium. Finally, the microbiome of the intestine is converted into a pathobiome, with an increase in disease-promoting bacteria and induction of virulence factors in commensal bacteria. Toxic factors can then leave the intestine via both portal blood flow and mesenteric lymph to cause distant organ damage. Conclusion: The gut plays a complex role in both health and critical illness. Here, we review gut integrity in both health and illness and highlight potential strategies for targeting the intestine for therapeutic gain in the intensive care unit.
While much of cancer immunology research has focused on anti-tumor immunity both systemically and within the tumor microenvironment, little is known about the impact of pre-existing malignancy on pathogen-specific immune responses. Here, we sought to characterize the antigen-specific CD8+ T cell response following a bacterial infection in the setting of pre-existing pancreatic adenocarcinoma. Mice with established subcutaneous pancreatic adenocarcinomas were infected with Listeria monocytogenes, and antigen-specific CD8+ T cell responses were compared to those in control mice without cancer. While the kinetics and magnitude of antigen-specific CD8+ T cell expansion and accumulation was comparable between the cancer and non-cancer groups, bacterial antigen-specific CD8+ T cells and total CD4+ and CD8+ T cells in cancer mice exhibited increased expression of the coinhibitory receptors BTLA, PD-1, and 2B4. Furthermore, increased inhibitory receptor expression was associated with reduced IFN-γ and increased IL-2 production by bacterial antigen-specific CD8+ T cells in the cancer group. Taken together, these data suggest that cancer's immune suppressive effects are not limited to the tumor microenvironment, but that pre-existing malignancy induces phenotypic exhaustion in T cells by increasing expression of coinhibitory receptors and may impair pathogen-specific CD8+ T cell functionality and differentiation.
by
Lindsay M. Margoles;
Rohit Mittal;
Nathan J. Klingensmith;
John D. Lyons;
Zhe Liang;
Mara A. Serbanescu;
Maylene E. Wagener;
Craig Coopersmith;
Mandy Ford
Sepsis is the leading cause of death in intensive care units in the US, and it is known that chronic alcohol use is associated with higher incidence of sepsis, longer ICU stays, and higher mortality from sepsis. Both sepsis and chronic alcohol use are associated with immune deficits such as decreased lymphocyte numbers, impaired innate immunity, delayed-type hypersensitivity reactions, and susceptibility to infections; however, understanding of specific pathways of interaction or synergy between these two states of immune dysregulation is lacking. This study therefore sought to elucidate mechanisms underlying the immune dysregulation observed during sepsis in the setting of chronic alcohol exposure. Using a murine model of chronic ethanol ingestion followed by sepsis induction via cecal ligation and puncture, we determined that while CD4+ and CD8+ T cells isolated from alcohol fed mice eventually expressed the same cellular activation markers (CD44, CD69, and CD43) and effector molecules (IFN-ã, TNF) as their water fed counterparts, there was an overall delay in the acquisition of these phenotypes. This early lag in T cell activation was associated with significantly reduced IL-2 production at a later timepoint in both the CD4+ and CD8+ T cell compartments in alcohol sepsis, as well as with a reduced accumulation of CD8dim activated effectors. Taken together, these data suggest that delayed T cell activation may result in qualitative differences in the immune response to sepsis in the setting of chronic alcohol ingestion.
Sepsis is primarily a disease of the aged, with increased incidence and mortality occurring in aged hosts. Heat shock protein (HSP) 70 plays an important role in both healthy aging and the stress response to injury. The purpose of this study was to determine the role of HSP70 in mediating mortality and the host inflammatory response in aged septic hosts. Sepsis was induced in both young (6–12week old) and aged (16–17 month old) HSP70−/− and wild type (WT) mice to determine if HSP70 modulated outcome in an age-dependent fashion. Young HSP70−/− and WT mice subjected to cecal ligation and puncture (CLP), Pseudomonas aeruginosa pneumonia or Streptococcus pneumoniae pneumonia had no differences in mortality, suggesting HSP70 does not mediate survival in young septic hosts. In contrast, mortality was higher in aged HSP70−/− mice than aged WT mice subjected to CLP (p=0.01), suggesting HSP70 mediates mortality in sepsis in an age-dependent fashion. Compared to WT mice, aged septic HSP70−/− mice had increased gut epithelial apoptosis and pulmonary inflammation. In addition, HSP70−/−mice had increased systemic levels of TNF-α, IL-6, IL-10 and IL-1β compared to WT mice. These data demonstrate that HSP70 is a key determinant of mortality in aged but not young hosts in sepsis. HSP70 may play a protective role in an age-dependent response to sepsis by preventing excessive gut apoptosis and both pulmonary and systemic inflammation.
Intestinal barrier dysfunction is thought to contribute to the development of multiple organ dysfunction syndrome in sepsis. Although there are similarities in clinical course following sepsis, there are significant differences in the host response depending on the initiating organism and time course of the disease, and pathways of gut injury vary widely in different preclinical models of sepsis. The purpose of this study was to determine whether the timecourse and mechanisms of intestinal barrier dysfunction are similar in disparate mouse models of sepsis with similar mortalities. FVB/N mice were randomized to receive cecal ligation and puncture (CLP) or sham laparotomy, and permeability was measured to fluoresceinisothiocyanate conjugated-dextran (FD-4) six to 48 h later. Intestinal permeability was elevated following CLP at all timepoints measured, peaking at 6 to 12 h. Tight junction proteins claudin 1, 2, 3, 4, 5, 7, 8, 13, and 15, Junctional Adhesion Molecule-A (JAM-A), occludin, and ZO-1 were than assayed by Western blot, real-time polymerase chain reaction, and immunohistochemistry 12 h after CLP to determine potential mechanisms underlying increases in intestinal permeability. Claudin 2 and JAM-A were increased by sepsis, whereas claudin-5 and occludin were decreased by sepsis. All other tight junction proteins were unchanged. A further timecourse experiment demonstrated that alterations in claudin-2 and occludin were detectable as early as 1 h after the onset of sepsis. Similar experiments were then performed in a different group of mice subjected to Pseudomonas aeruginosa pneumonia. Mice with pneumonia had an increase in intestinal permeability similar in timecourse and magnitude to that seen in CLP. Similar changes in tight junction proteins were seen in both models of sepsis although mice subjected to pneumonia also had a marked decrease in ZO-1 not seen in CLP. These results indicate that two disparate, clinically relevant models of sepsis induce a significant increase in intestinal permeability mediated through a common pathway involving alterations in claudin 2, claudin 5, JAM-A, and occludin although model-specific differences in ZO-1 were also identified.
Background
Limited data are available on the incidence and risk factors for infection among patients requiring home parenteral nutrition (HPN).
Methods
Retrospective study of 101 consecutive adults (63 female, 38 male) discharged on HPN from Emory University Hospital, Atlanta, GA. New bloodstream infections (BSI) requiring re-hospitalization and other infections were evaluated.
Results
Most infections (75%) developed during the initial 6 months after hospital discharge; rates of BSI were particularly high during the first four months. A total of 56 patients (55.4%) developed a total of 102 BSIs (11.5 BSI/1000 catheter-days). Most BSIs were attributed to Gram positive organisms (46%) including coagulase-negative staphylococcus, staphylococcus aureus, enterococcus species, and others, followed by Candida species (20%) and Gram negative organisms (13%). Twenty-one percent of BSIs were polymicrobial. The BSI incidence rate ratio (IRR) was significantly increased for patients with mean pre-hospital discharge blood glucose (BG) concentrations in the highest quartile versus the lowest quartile; IRR 2.4; P = 0.017). Patients with a peripherally inserted central catheter (PICC) versus non-PICC central venous catheters had significantly higher rates of BSI (p = 0.018). Thirty-nine (38.6%) patients developed 81 non-BSI infections, including pneumonia, urinary tract infections, and surgical site infections. Post-discharge PN dextrose, lipid, and total calorie doses were unrelated to BSI but variably related to the rate of non-BSI.
Conclusions
Adult HPN patients exhibit a very high incidence of post-hospital infections. Higher mean BG levels during pre-discharge hospitalization and use of PICCs at discharge are associated with an increased risk of BSI in the post-discharge home setting.
by
William O. Cooper;
Oscar Guillamondegui;
O. Joe Hines;
C. Scott Hultman;
Rachel R. Kelz;
Perry Shen;
David A. Spain;
John F Sweeney;
Ilene N. Moore;
Joseph Hopkins;
Ira R Horowitz;
Russell M. Howerton;
J. Wayne Meredith;
Nathan O Spell III;
Patricia Sullivan;
Henry J. Domenico;
James W. Pichert;
Thomas F. Catron;
Lynn E. Webb;
Roger R. Dmochowski;
Jan Karrass;
Gerald B. Hickson
IMPORTANCE Unsolicited patient observations are associated with risk of medical malpractice claims. Because lawsuits may be triggered by an unexpected adverse outcome superimposed on a strained patient-physician relationship, a question remains as to whether behaviors that generate patient dissatisfaction might also contribute to the genesis of adverse outcomes themselves. OBJECTIVE To examine whether patients of surgeons with a history of higher numbers of unsolicited patient observations are at greater risk for postoperative complications than patients whose surgeons generate fewer such unsolicited patient observations. DESIGN, SETTING, AND PARTICIPANTS This retrospective cohort study used data from 7 academic medical centers participating in the National Surgical Quality Improvement Program and the Vanderbilt Patient Advocacy Reporting System from January 1, 2011, to December 31, 2013. Patients older than 18 years included in the National Surgical Quality Improvement Program who underwent inpatient or outpatient operations at 1 of the participating sites during the study period were included. Patients were excluded if the attending surgeon had less than 24 months of data in the Vanderbilt Patient Advocacy Reporting System preceding the date of the operation. Data analysis was conducted from June 1, 2015, to October 20, 2016. EXPOSURES Unsolicited patient observations for the patient's surgeon in the 24 months preceding the date of the operation. MAIN OUTCOMES AND MEASURES Postoperative surgical or medical complications as defined by the National Surgical Quality Improvement Program within 30 days of the operation of interest. RESULTS Among the 32 125 patients in the cohort (13 230 men, 18 895 women; mean [SD] age, 55.8 [15.8] years), 3501 (10.9%) experienced a complication, including 1754 (5.5%) surgical and 2422 (7.5%) medical complications. Prior unsolicited patient observations for a surgeon were significantly associated with the risk of a patient having any complication (odds ratio, 1.0063; 95%CI, 1.0004-1.0123; P = .03), any surgical complication (odds ratio, 1.0104; 95%CI, 1.0022-1.0186; P = .01), any medical complication (odds ratio, 1.0079; 95%CI, 1.0009-1.0148; P = .03), and being readmitted (odds ratio, 1.0088, 95%CI, 1.0024-1.0151; P = .007). The adjusted rate of complications was 13.9% higher for patients whose surgeon was in the highest quartile of unsolicited patient observations compared with patients whose surgeon was in the lowest quartile. CONCLUSIONS AND RELEVANCE Patients whose surgeons have large numbers of unsolicited patient observations in the 24 months prior to the patient's operation are at increased risk of surgical and medical complications. Efforts to promote patient safety and address risk of malpractice claims should continue to focus on surgeons' ability to communicate respectfully and effectively with patients and other medical professionals.
Clinicians depend on recognizing particular critical illnesses (such as sepsis and cardiac failure) from patterns of vital signs. The relationship between a vital sign pattern and a specific condition is explored.
Background: Each year, 200,000 patients undergo an in-hospital cardiac arrest (IHCA), with approximately 15-20% surviving to discharge. Little is known, however, about the long-term prognosis of these patients after discharge. Previous efforts to describe out-of-hospital survival of IHCA patients have been limited by small sample sizes and narrow patient populations. Methods: A single institution matched cohort study was undertaken to describe mortality following IHCA. Patients surviving to discharge following an IHCA between 2008 and 2010 were matched on age, sex, race and hospital admission criteria with non-IHCA hospital controls and follow-up between 9 and 45 months. Kaplan-Meier curves and Cox PH models assessed differences in survival. Results: Of the 1262 IHCAs, 20% survived to hospital discharge. Of those discharged, survival at 1 year post-discharge was 59% for IHCA patients and 82% for controls (p < 0.0001). Hazard ratios (IHCA vs. controls) for mortality were greatest within the 90 days following discharge (HR = 2.90, p < 0.0001) and decreased linearly thereafter, with those surviving to one year post-discharge having an HR for mortality below 1.0. Survival after discharge varied amongst IHCA survivors. When grouped by discharge destination, out of hospital survival varied; in fact, IHCA patients discharged home without services demonstrated no survival difference compared to their non-IHCA controls (HR 1.10, p = 0.72). IHCA patients discharged to long-term hospital care or hospice, however, had a significantly higher mortality compared to matched controls (HR 3.91 and 20.3, respectively; p < 0.0001). Conclusion: Among IHCA patients who survive to hospital discharge, the highest risk of death is within the first 90 days after discharge. Additionally, IHCA survivors overall have increased long-term mortality vs. controls. Survival rates were varied widely with different discharge destinations, and those discharged to home, skilled nursing facilities or to rehabilitation services had survival rates no different than controls. Thus, increased mortality was primarily driven by patients discharged to long-term care or hospice.