Morbidity and mortality from sepsis remains unacceptably high. Large variability in clinical practice, plus the increasing awareness that certain processes of care associated with improved critical...

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Severe sepsis and septic shock

Sepsis - which is a severe life-threatening infection with organ dysfunction - initiates a complex interplay of host pro-inflammatory and anti-inflammatory processes. Sepsis can be considered a race to the death between the pathogens and the host immune system, and it is the proper balance between the often competing pro- and anti-inflammatory pathways that determines the fate of the individual. Although the field of sepsis research has witnessed the failure of many highly touted clinical trials, a better understanding of the pathophysiological basis of the disorder and the mechanisms responsible for the associated pro- and anti-inflammatory responses provides a novel approach for treating this highly lethal condition. Biomarker-guided immunotherapy that is administered to patients at the proper immune phase of sepsis is potentially a major advance in the treatment of sepsis and in the field of infectious disease.

/pdf/sepsis-induced-immunosuppression-from-cellular-dysfunctions-425knwqbvv.pdf

Sepsis-induced immunosuppression: from cellular dysfunctions to immunotherapy

Summary Failures of highly touted trials have caused experts to call for re-evaluation of the current approach toward sepsis. New research has revealed key pathogenic mechanisms; autopsy results have shown that most patients admitted to intensive care units for treatment of sepsis had unresolved septic foci at post mortem, suggesting that patients were unable to eradicate invading pathogens and were more susceptible to nosocomial organisms, or both. These results suggest that therapies that improve host immunity might increase survival. Additional work showed that cytokine production by splenocytes taken post mortem from patients who died of sepsis is profoundly suppressed, possibly because of so-called T-cell exhaustion—a newly recognised immunosuppressive mechanism that occurs with chronic antigenic stimulation. Results from two clinical trials of biomarker-guided therapeutic drugs that boosted immunity showed promising findings in sepsis. Collectively, these studies emphasise the degree of immunosuppression that occurs in sepsis, and explain why many previous sepsis trials which were directed at blocking inflammatory mediators or pathogen recognition signalling pathways failed. Finally, highly encouraging results from use of the new immunomodulatory molecules interleukin 7 and anti-programmed cell death 1 in infectious disease point the way for possible use in sepsis. We hypothesise that immunoadjuvant therapy represents the next major advance in sepsis.

/pdf/immunosuppression-in-sepsis-a-novel-understanding-of-the-19ommginkb.pdf

Immunosuppression in sepsis: a novel understanding of the disorder and a new therapeutic approach

Sepsis is defined as a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. In sepsis, the immune response that is initiated by an invading pathogen fails to return to homeostasis, thus culminating in a pathological syndrome that is characterized by sustained excessive inflammation and immune suppression. Our understanding of the key mechanisms involved in the pathogenesis of sepsis has increased tremendously, yet this still needs to be translated into novel targeted therapeutic strategies. Pivotal for the clinical development of new sepsis therapies is the selection of patients on the basis of biomarkers and/or functional defects that provide specific insights into the expression or activity of the therapeutic target.

The immunopathology of sepsis and potential therapeutic targets

For more than two decades, sepsis was defined as a microbial infection that produces fever (or hypothermia), tachycardia, tachypnoea and blood leukocyte changes. Sepsis is now increasingly being considered a dysregulated systemic inflammatory and immune response to microbial invasion that produces organ injury for which mortality rates are declining to 15-25%. Septic shock remains defined as sepsis with hyperlactataemia and concurrent hypotension requiring vasopressor therapy, with in-hospital mortality rates approaching 30-50%. With earlier recognition and more compliance to best practices, sepsis has become less of an immediate life-threatening disorder and more of a long-term chronic critical illness, often associated with prolonged inflammation, immune suppression, organ injury and lean tissue wasting. Furthermore, patients who survive sepsis have continuing risk of mortality after discharge, as well as long-term cognitive and functional deficits. Earlier recognition and improved implementation of best practices have reduced in-hospital mortality, but results from the use of immunomodulatory agents to date have been disappointing. Similarly, no biomarker can definitely diagnose sepsis or predict its clinical outcome. Because of its complexity, improvements in sepsis outcomes are likely to continue to be slow and incremental.

Sepsis and septic shock

Context Severe sepsis is typically characterized by initial cytokine-mediated hyperinflammation. Whether this hyperinflammatory phase is followed by immunosuppression is controversial. Animal studies suggest that multiple immune defects occur in sepsis, but data from humans remain conflicting. Objectives To determine the association of sepsis with changes in host innate and adaptive immunity and to examine potential mechanisms for putative immunosuppression. Design, Setting, and Participants Rapid postmortem spleen and lung tissue harvest was performed at the bedsides of 40 patients who died in intensive care units (ICUs) of academic medical centers with active severe sepsis to characterize their immune status at the time of death (2009-2011). Control spleens (n = 29) were obtained from patients who were declared brain-dead or had emergent splenectomy due to trauma; control lungs (n = 20) were obtained from transplant donors or from lung cancer resections. Main Outcome Measures Cytokine secretion assays and immunophenotyping of cell surface receptor-ligand expression profiles were performed to identify potential mechanisms of immune dysfunction. Immunohistochemical staining was performed to evaluate the loss of immune effector cells. Results The mean ages of patients with sepsis and controls were 71.7 (SD, 15.9) and 52.7 (SD, 15.0) years, respectively. The median number of ICU days for patients with sepsis was 8 (range, 1-195 days), while control patients were in ICUs for 4 or fewer days. The median duration of sepsis was 4 days (range, 1-40 days). Compared with controls, anti-CD3/anti-CD28–stimulated splenocytes from sepsis patients had significant reductions in cytokine secretion at 5 hours: tumor necrosis factor, 5361 (95% CI, 3327-7485) pg/mL vs 418 (95% CI, 98-738) pg/mL; interferon γ, 1374 (95% CI, 550-2197) pg/mL vs 37.5 (95% CI, −5 to 80) pg/mL; interleukin 6, 3691 (95% CI, 2313-5070) vs 365 (95% CI, 87-642) pg/mL; and interleukin 10, 633 (95% CI, −269 to 1534) vs 58 (95% CI, −39 to 156) pg/mL; (P  Conclusions Patients who die in the ICU following sepsis compared with patients who die of nonsepsis etiologies have biochemical, flow cytometric, and immunohistochemical findings consistent with immunosuppression. Targeted immune-enhancing therapy may be a valid approach in selected patients with sepsis.

https://jamanetwork.com/journals/jama/articlepdf/1104735/jce15006_2594_2605.pdf

Immunosuppression in patients who die of sepsis and multiple organ failure.

Immunosuppression in Patients Who Die of Sepsis and Multiple Organ Failure

Background: Emergency laparotomy for abdominal trauma is associated with high rates of surgical site infection (SSI). A protocol for antimicrobial prophylaxis (AMP) for trauma laparotomy was implemented to determine whether SSI could be reduced by adhering to established principles of AMP. Patients and Methods: A protocol utilizing ertapenem administered immediately before initiation of trauma laparotomy was adopted. Compliance with measures of adequate AMP were determined before and after protocol implementation, as were rates of SSI and other infections related to abdominal trauma. Univariable and multivariable analyses were performed to determine risk factors for development of infection related to trauma laparotomy. Results: Over a four-year period, 320 patient operations were reviewed. Ertapenem use for prophylaxis increased to 54% in the post-intervention cohort. Compliance with individual measures of appropriate AMP improved modestly. Overall, infections related to trauma laparotomy decreased by 46% (absolute decrease of 13%) in the post-intervention cohort. Multivariable analysis confirmed that treatment during the post-intervention phase was associated with this decrease, with a separate analysis suggesting that ertapenem use was an important factor in this decrease. Conclusions: Development of a standardized protocol for AMP in trauma laparotomy led to decreases in infectious complications after that procedure.

Stephen D. Jarman

Papers

Immunosuppression in patients who die of sepsis and multiple organ failure.

Immunosuppression in Patients Who Die of Sepsis and Multiple Organ Failure

Reduction of Surgical Site Infection After Trauma Laparotomy Through Use of a Specific Protocol for Antibiotic Prophylaxis.