Richard D. Collage

Augmenting Autophagy to Treat Acute Kidney Injury during Endotoxemia in Mice

Objective To determine that 1) an age-dependent loss of inducible autophagy underlies the failure to recover from AKI in older, adult animals during endotoxemia, and 2) pharmacologic induction of autophagy, even after established endotoxemia, is of therapeutic utility in facilitating renal recovery in aged mice. Design Murine model of endotoxemia and cecal ligation and puncture (CLP) induced acute kidney injury (AKI). Setting Academic research laboratory. Subjects C57Bl/6 mice of 8 (young) and 45 (adult) weeks of age. Intervention Lipopolysaccharide (1.5 mg/kg), Temsirolimus (5 mg/kg), AICAR (100 mg/kg). Measurements and Main Results: Herein we report that diminished autophagy underlies the failure to recover renal function in older adult mice utilizing a murine model of LPS-induced AKI. The administration of the mTOR inhibitor temsirolimus, even after established endotoxemia, induced autophagy and protected against the development of AKI. Conclusions These novel results demonstrate a role for autophagy in the context of LPS-induced AKI and support further investigation into like interventions that have potential to alter the natural history of disease.

Calcium/calmodulin-dependent protein kinase (CaMK) Iα mediates the macrophage inflammatory response to sepsis

Dysregulated Ca2+ handling is prevalent during sepsis and postulated to perpetuate the aberrant inflammation underlying subsequent organ dysfunction and death. The signal transduction cascades mediating these processes are unknown. Here, we identify that CaMKIα mediates the Mφ response to LPS in vitro and the inflammation and organ dysfunction of sepsis in vivo. We show that LPS induced active pThr177‐CaMKIα in RAW 264.7 cells and murine peritoneal Mφ, which if inhibited biochemically with STO609 (CaMKK inhibitor) or by RNAi, reduces LPS‐induced production of IL‐10. Transfection of constitutively active CaMKIα (CaMKI293), but not a kinase‐deficient mutant (CaMKI293K49A), induces IL‐10 release. This production of IL‐10 is mediated by CaMKIα‐dependent regulation of p38 MAPK activation. CaMKIα activity also mediates the cellular release of HMGB1 by colocalizing with and regulating the packaging of HMGB1 into secretory lysosomes. During endotoxemia, mice receiving in vivo CaMKIαRNAi display reduced systemic concentrations of IL‐10 and HMGB1 in comparison with mice receiving NTRNAi. These data support the biological relevance of CaMKIα‐dependent IL‐10 production and HMGB1 secretion. In a CLP model of sepsis, CaMKIαRNAi mice display reduced systemic concentrations of IL‐10, IL‐6, TNF‐α, and HMGB1 in comparison with NTRNAi mice, which correlate with reductions in the development of renal dysfunction. These data support that CaMKIα signaling is integral to the Mφ responding to LPS and may also be operant in vivo in regulating the inflammation and organ dysfunction consequent to sepsis.

Abdominal Wall Infections with in situ Mesh

BACKGROUND Synthetic mesh is used commonly in the repair of abdominal wall hernias. Infection at the surgical site where mesh is present poses a formidable clinical problem. METHODS The current surgical literature was reviewed to formulate accepted approaches to the management of hernia repairs with infected mesh. RESULTS Prevention of mesh infection is best achieved by judicious use of systemic antibiotics. Topical antibiotics often are used without convincing evidence to support their value. Laparoscopic repairs have lower infection rates than open repairs. Evidence is lacking to support lower rates of infection with mesh of specific composition or with antibacterial agents that coat the mesh. The diagnosis of mesh infection is principally a clinical one. Repairs of infected mesh usually necessitate antibiotics and removal of the foreign material. Clinical judgment is required for attempts at salvaging portions of the mesh. Component separation or biological materials may be used in those circumstances for hernia repair in which large defects are created by removal of the infected synthetic material. CONCLUSIONS Prevention of mesh infections remains the best strategy. Clinical judgment is essential in determining the degree of mesh removal. Continued clinical studies are necessary to improve the outcomes of established mesh infection in hernia repairs.

CaMKIV-Dependent Preservation of mTOR Expression Is Required for Autophagy during Lipopolysaccharide-Induced Inflammation and Acute Kidney Injury

Autophagy, an evolutionarily conserved homeostasis process regulating biomass quantity and quality, plays a critical role in the host response to sepsis. Recent studies show its calcium dependence, but the calcium-sensitive regulatory cascades have not been defined. In this study, we describe a novel mechanism in which calcium/calmodulin-dependent protein kinase IV (CaMKIV), through inhibitory serine phosphorylation of GSK-3β and inhibition of FBXW7 recruitment, prevents ubiquitin proteosomal degradation of mammalian target of rapamycin (mTOR) and thereby augments autophagy in both the macrophage and the kidney. Under the conditions of sepsis studied, mTOR expression and activity were requisite for autophagy, a paradigm countering the current perspective that prototypically, mTOR inhibition induces autophagy. CaMKIV–mTOR-dependent autophagy was fundamentally important for IL-6 production in vitro and in vivo. Similar mechanisms were operant in the kidney during endotoxemia and served a cytoprotective role in mitigating acute kidney injury. Thus, CaMKIV–mTOR-dependent autophagy is conserved in both immune and nonimmune/parenchymal cells and is fundamental for the respective functional and adaptive responses to septic insult.

Calcium supplementation during sepsis exacerbates organ failure and mortality via calcium/calmodulin-dependent protein kinase kinase signaling.

Background:Calcium plays an essential role in nearly all cellular processes. As such, cellular and systemic calcium concentrations are tightly regulated. During sepsis, derangements in such tight regulation frequently occur, and treating hypocalcemia with parenteral calcium administration remains the current practice guideline. Objective:We investigated whether calcium administration worsens mortality and organ dysfunction using an experimental murine model of sepsis and explored the mechanistic role of the family of calcium/calmodulin-dependent protein kinases in mediating these physiological effects. To highlight the biological relevance of these observations, we conducted a translational study of the association between calcium administration, organ dysfunction, and mortality among a cohort of critically ill septic ICU patients. Design:Prospective, randomized controlled experimental murine study and observational clinical cohort analysis. Setting:University research laboratory and eight ICUs at a tertiary care center. Patients:A cohort of 870 septic ICU patients. Subjects:C57Bl/6 and CaMKK−/− mice. Interventions:Mice underwent cecal ligation and puncture polymicrobial sepsis and were administered with calcium chloride (0.25 or 0.25 mg/kg) or normal saline. Measurements and Main Results:Administering calcium chloride to septic C57Bl/6 mice heightened systemic inflammation and vascular leak, exacerbated hepatic and renal dysfunction, and increased mortality. These events were significantly attenuated in CaMKK−/− mice. In a risk-adjusted analysis of septic patients, calcium administration was associated with an increased risk of death, odds ratio 1.92 (95% CI, 1.00−3.68; p = 0.049), a significant increase in the risk of renal dysfunction, odds ratio 4.74 (95% CI, 2.48−9.08; p < 0.001), and a significant reduction in ventilator-free days, mean decrease 3.29 days (0.50−6.08 days; p = 0.02). Conclusions:Derangements in calcium homeostasis occur during sepsis that is sensitive to calcium administration. This altered calcium signaling, transduced by the calmodulin-dependent protein kinase kinase cascade, mediates heightened inflammation and vascular leak that culminates in elevated organ dysfunction and mortality. In the clinical management of septic patients, calcium supplementation provides no benefit and may impose harm.

CaMKIα Regulates AMP Kinase–Dependent, TORC-1–Independent Autophagy during Lipopolysaccharide-Induced Acute Lung Neutrophilic Inflammation

Autophagy is an evolutionarily conserved cytoplasmic process regulated by the energy rheostats mammalian target of rapamycin and AMP kinase (AMPK) that recycles damaged or unused proteins and organelles. It has been described as an important effector arm of immune cells. We have shown that the cytoplasmically oriented calcium/calmodulin-dependent protein kinase (CaMK)Iα regulates the inflammatory phenotype of the macrophage (Mϕ). In this study, we hypothesize that CaMKIα mediates Mϕ autophagy. LPS induced autophagy in RAW 264.7 cells and murine peritoneal Mϕ that was attenuated with biochemical CaMK inhibition or CaMKIα small interfering RNA (siRNA). Inhibition of CaMKIα reduced LPS-induced p-Thr172AMPK and target of rapamycin complex-1 activity, and expression of a constitutively active CaMKIα but not a kinase-deficient mutant induced p-Thr172AMPK and autophagy that was attenuated by the AMPK inhibitor compound C. Coimmunoprecipitation and in vitro kinase assays demonstrated that CaMKIα activates AMPK, thereby inducing ATG7, which also localizes to this CaMKIα/AMPK complex. During LPS-induced lung inflammation, C57BL/6 mice receiving CaMKIαsiRNA displayed reduced lung and bronchoalveolar immune cell autophagy that correlated with reduced neutrophil recruitment, myeloperoxidase activity, and air space cytokine concentration. Independently inhibiting autophagy, using siRNA targeting the PI3K VPS34, yielded similar reductions in lung autophagy and neutrophil recruitment. Thus, a novel CaMKIα/AMPK pathway is rapidly activated in Mϕ exposed to LPS and regulates an early autophagic response, independent of target of rapamycin complex-1 inhibition. These mechanisms appear to be operant in vivo in orchestrating LPS-induced lung neutrophil recruitment and inflammation.

Incidental radiographic findings after injury: dedicated attention results in improved capture, documentation, and management.

BACKGROUND With liberal use of computed tomography in the diagnostic management of trauma patients, incidental findings are common and represent a major patient-care and medical-legal concern. Consequently, we began an initiative to capture, notify, and documentadequately incidental finding events with a dedicated incidental finding coordinator. We hypothesized a dedicated incidental finding coordinator would increase incidental finding capture and promote notification, follow-up, and documentation of incidental finding events. METHODS A quality-improvement project to record and follow-up incidental findings postinjury was initiated at our level I trauma center (April 2007-March 2008, prededicated incidental finding). Because of concerns for inadequate documentation of identified incidental finding events, we implemented a dedicated incidental finding coordinator (April 2008-March 2009, postdedicated incidental finding). The dedicated incidental finding coordinator documented incidental findings daily from trauma admission radiology final reads. Incidental findings were divided into 3 groups; category 1: attention prior to discharge; category 2: follow-up with primary doctor within 2 weeks; category 3: no specific follow-up. For category 1 incidental findings, in-hospital consultation of the appropriate service was verified. On discharge, patient notification, follow-up, and documentation of events were confirmed. Certified mail or telephone contact was used to notify either the patient or the primary doctor in those who lacked appropriate notification or documentation. RESULTS Admission rates and incidental finding categories were similar across the 2 time periods. Implementation of a dedicated incidental finding coordinator resulted in more than a 165% increase in incidental finding capture (n = 802 vs n = 302; P < .001). Patient notification was attempted, and appropriate documentation of events was confirmed in 99.8% of patients. Patient notification was verified, and follow-up was initiated in 95.8% of cases. CONCLUSION The implementation of a dedicated incidental finding coordinator resulted in more than a 2.5-fold higher capture of incidental findings. Dedicated attention to incidental findings resulted in a near complete initiation of patient notification, follow-up, and hospital record documentation of incidental finding events. Inadequate patient notification and follow-up would delay appropriate care and potentially would result in morbidity or even mortality. A dedicated incidental finding coordinator represents a potential solution to this patient-care and medical-legal dilemma.

Blue light reduces organ injury from ischemia and reperfusion

Significance It is well established that light regulates mammalian biology. And yet, we have been unable to define and thus harness the underlying mechanisms so as to apply them to alter the course of human disease. In this study we determine that the spectrum of light is a critical determinant of its effect on critical illness. We show that an acute and short (24 h) exposure to high-illuminance (1,400 lx) blue spectrum (peak 442 nm) light prior to ischemia/reperfusion (I/R) significantly attenuates the degree of organ injury. Our characterization of the biological mechanisms through which blue light beneficially alters the cellular response to I/R provides an opportunity to develop novel therapeutics for the prevention and treatment of many diseases. Evidence suggests that light and circadian rhythms profoundly influence the physiologic capacity with which an organism responds to stress. However, the ramifications of light spectrum on the course of critical illness remain to be determined. Here, we show that acute exposure to bright blue spectrum light reduces organ injury by comparison with bright red spectrum or ambient white fluorescent light in two murine models of sterile insult: warm liver ischemia/reperfusion (I/R) and unilateral renal I/R. Exposure to bright blue light before I/R reduced hepatocellular injury and necrosis and reduced acute kidney injury and necrosis. In both models, blue light reduced neutrophil influx, as evidenced by reduced myeloperoxidase (MPO) within each organ, and reduced the release of high-mobility group box 1 (HMGB1), a neutrophil chemotactant and key mediator in the pathogenesis of I/R injury. The protective mechanism appeared to involve an optic pathway and was mediated, in part, by a sympathetic (β3 adrenergic) pathway that functioned independent of significant alterations in melatonin or corticosterone concentrations to regulate neutrophil recruitment. These data suggest that modifying the spectrum of light may offer therapeutic utility in sterile forms of cellular injury.

1379: BLUE LIGHT THERAPY MODULATES THE SYSTEMIC RESPONSE TO SEPSIS IN MICE AND HUMANS.

Crit Care Med 2016 • Volume 44 • Number 12 (Suppl.) clinical outcomes and add significantly to healthcare burden and cost. Little data is available on CDI complicating patients hospitalized with septic shock (SS). We sought to determine the prevalence of CDI in hospitalized patients with SS and the impact of CDI on clinical outcomes in these patients. Methods: The National Inpatient Sample (NIS) was used to identify hospitalizations from 2007 to 2013 of adults (age > 18 years) with SS. Septic shock was identified by either ICD9-CM code for SS or vasopressor use associated with ICD-9 codes of sepsis, severe sepsis, septicemia, bacteremia, or fungemia. CDI was identified by secondary diagnosis ICD-9-CM code. Demographic data was obtained from NIS database. Primary outcome was prevalence of CDI among patients with SS. Secondary outcomes were: mortality and hospital length of stay (LOS) associated with CDI. Results: There were 2,031,739 hospitalizations with SS between 2007 and 2013. CDI was present in 8.2% of patients with SS. The prevalence of CDI in SS remained stable between 2007 and 2013. Patients with CDI were older (mean age 69.8 (+ 14.7 vs 66.8 (+ 15.9) years, p <0.001). The in-hospital mortality of SS complicated by CDI was comparable to those without CDI (37.1% versus 37.0%, p=0.48). The median LOS was significantly longer for patients with CDI (13 vs 9 days, p<0.001). Prolonged LOS (>75th percentile of LOS for SS cases, 17 days) was observed in 36.9% of SS patients with CDI vs 22.7% without CDI (p<0.001). After adjusting for age, gender, race, and Charlson Comorbidity Index; the odds of prolonged LOS with presence of CDI was significantly greater (OR 2.11, 95%CI 2.06 – 2.15, p<0.001). Conclusions: CDI complicating septic shock is associated with a significant increase in length of stay but no increase in in-hospital mortality.