Activation of Invariant Natural Killer T Cells Redirects the Inflammatory Response in Neonatal Sepsis.

Sepsis is the third leading cause of death in the neonatal population, due to susceptibility to infection conferred by immaturity of both the innate and adaptive components of the immune system. Invariant natural killer T (iNKT) cells are specialized adaptive immune cells that possess important innate-like characteristics and have not yet been well-studied in septic neonates. We hypothesized that iNKT cells would play an important role in mediating the neonatal immune response to sepsis. To study this, we subjected 5- to 7-day-old neonatal C57BL/6 mice to sepsis by intraperitoneal (i.p.) cecal slurry (CS) injection. Thirty hours prior to or immediately following sepsis induction, pups received i.p. injection of the iNKT stimulator KRN7000 (KRN, 0.2 µg/g) or vehicle. Ten hours after CS injection, blood and tissues were collected for various analyses. Thirty-hour pretreatment with KRN resulted in better outcomes in inflammation, lung injury, and survival, while immediate treatment with KRN resulted in worse outcomes compared to vehicle treatment. We further analyzed the activation status of neonatal iNKT cells for 30 h after KRN administration, and showed a peak in frequency of CD69 expression on iNKT cells and serum IFN-γ levels at 5 and 10 h, respectively. We then used CD1d knockout neonatal mice to demonstrate that KRN acts through the major histocompatibility complex-like molecule CD1d to improve outcomes in neonatal sepsis. Finally, we identified that KRN pretreatment exerts its protective effect by increasing systemic levels of TGF-ß1. These findings support the importance of iNKT cells for prophylactic immunomodulation in neonates susceptible to sepsis.

Inhibition of necroptosis attenuates lung injury and improves survival in neonatal sepsis.

BACKGROUND: Neonatal sepsis represents a unique therapeutic challenge owing to an immature immune system. Necroptosis is a form of programmed cell death that has been identified as an important mechanism of inflammation-induced cell death. Receptor-interacting protein kinase 1 plays a key role in mediating this process. We hypothesized that pharmacologic blockade of receptor-interacting protein kinase 1 activity would be protective in neonatal sepsis. METHODS: Sepsis was induced in C57BL/6 mouse pups (5-7 days old) by intraperitoneal injection of adult cecal slurry. At 1 hour after cecal slurry injection, the receptor-interacting protein kinase 1 inhibitor necrostatin-1 (10 µg/g body weight) or vehicle (5% dimethyl sulfoxide in phosphate buffered saline) was administered via retro-orbital injection. At 20 hours after cecal slurry injection, blood and lung tissues were collected for various analyses. RESULTS: At 20 hours after sepsis induction, vehicle-treated pups showed a marked increase in serum levels of interleukin 6, interleukin 1-beta, and interleukin 18 compared to sham. With necrostatin-1 treatment, serum levels of interleukin 6, interleukin 1-beta, and interleukin 18 were decreased by 77%, 81%, and 63%, respectively, compared to vehicle. In the lungs, sepsis induction resulted in a 232-, 10-, and 2.8-fold increase in interleukin 6, interleukin 1-beta, and interleukin 18 mRNA levels compared to sham, while necrostatin-1 treatment decreased these levels to 40-, 4-, and 0.8-fold, respectively. Expressions of the neutrophil chemokines keratinocyte chemoattractant and macrophage-inflammatory-protein-2 were also increased in the lungs in sepsis, while necrostatin-1 treatment decreased these levels by 81% and 61%, respectively, compared to vehicle. In addition, necrostatin-1 treatment significantly improved the lung histologic injury score and decreased lung apoptosis in septic pups. Finally, treatment with necrostatin-1 increased the 7-day survival rate from 0% in the vehicle-treated septic pups to 29% (P = .11). CONCLUSION: Inhibition of receptor-interacting protein kinase 1 by necrostatin-1 decreases systemic and pulmonary inflammation, decreases lung injury, and increases survival in neonatal mice with sepsis. Targeting the necroptosis pathway might represent a new therapeutic strategy for neonatal sepsis.

Deficiency of receptor-interacting protein kinase 3 (RIPK3) attenuates inflammation and organ injury in neonatal sepsis.

INTRODUCTION: Sepsis is the third leading cause of morbidity and mortality in neonates. Sepsis in neonates is characterized as the systemic inflammation owing to infection within the first 28days after birth. The molecular mechanism causing the exaggerated inflammation phenotype in neonates has not been completely elucidated. Receptor interacting protein kinase 3 (RIPK3) is a protein identified as a mediator in programmed necrosis or necroptosis. We hypothesize that RIPK3 could be responsible for the inflammatory response in neonates and that deficiency in the RIPK3 protein attenuates inflammation and organ injury in neonatal sepsis. METHODS: Male and female C57BL6 wild-type (WT) and RIPK3 knock-out (KO) newborn mice aged 5-7days (3-4g body weight) were injected intraperitoneally with 0.9mg/g cecal slurry (CS). At 10h after injection, the newborns were euthanized and blood, the lungs and gut tissues were collected. RESULTS: At 10h after CS injection, serum cytokines IL-6 and IL-1ß in the WT mice were increased by 511- and 43-fold whereas in KO mice, these levels were increased by 166-fold and 22-fold, respectively. Lung IL-1ß in the WT mice increased by 7-fold after CS injection whereas only a 4-fold increase was seen in the KO mice. In the lungs of CS injected KO mice, the injury score, MIP-2 mRNA, myeloperoxidase (MPO) activity and TUNEL staining were significantly reduced by 76%, 70%, 26% and 74%, respectively compared to the CS WT mice. Gut TUNEL staining was also reduced by 80%. CONCLUSION: The deficiency in RIPK3 attenuated serum and lung cytokines, lung injury and neutrophil infiltration and lung and gut apoptosis. These data suggest that RIPK3, in part, is responsible for the systemic inflammatory response in neonatal sepsis.

SRT1720, a sirtuin 1 activator, attenuates organ injury and inflammation in sepsis.

BACKGROUND: Sepsis affects 800,000 patients in the United States annually with a mortality rate of up to 30%. Recent studies suggest that sepsis-associated metabolic derangements due to hypoxic tissue injury, impaired oxygen utilization, and mitochondrial dysfunction contribute to mortality. Sirtuin 1 (Sirt1) is a crucial modulator of energy metabolism during starvation states and has anti-inflammatory effects. Here, we hypothesized that SRT1720, a Sirt1 activator, could attenuate the severity of sepsis. MATERIALS AND METHODS: Male C57BL/6 mice (20-25 g) were subjected to cecal ligation and puncture (CLP) to induce sepsis. SRT1720 (5 or 20 mg/kg BW) or 10% dimethyl sulfoxide (vehicle) in 0.2-mL saline was injected intravenously at 5 h after CLP. Control animals were not subjected to any surgery. Blood and liver samples were harvested at 20 h after CLP for analysis. RESULTS: Administration of SRT1720 markedly reduced the serum levels of tissue injury markers (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase) and renal injury markers (blood urea nitrogen and creatinine) in a dose-dependent manner after CLP. Furthermore, the levels of proinflammatory cytokines interleukin (IL)-1ß and IL-6 in the serum and liver were significantly inhibited by SRT1720 treatment after CLP. SRT1720 treatment resulted in a significantly decreased mRNA expression of inflammasome components (nucleotide oligomerization domain-like receptor protein 3, adapter apoptosis-associated speck-like protein containing caspase-recruitment domain, IL-1ß, and IL-18) in the liver, compared with the vehicle group. CONCLUSIONS: SRT1720 treatment attenuates multiorgan injury in septic mice. SRT1720 treatment also decreases the production of proinflammatory cytokines and reduces inflammasome activation. Thus, pharmacologic stimulation of Sirt1 may present a promising therapeutic strategy for sepsis.

Treatment with milk fat globule epidermal growth factor-factor 8 (MFG-E8) reduces inflammation and lung injury in neonatal sepsis.

BACKGROUND: Sepsis remains one of the leading causes of infant death worldwide. It is characterized by uncontrolled inflammatory responses due to proven bacterial infection. Despite improvement in supportive care and the availability of effective antibiotics, no specific therapy targeting the dysregulated inflammatory response is available for neonatal sepsis. Milk fat globule epidermal growth factor-factor 8 (MFG-E8) is a secretory glycoprotein abundantly present in human milk. MFG-E8 suppresses the systemic inflammatory responses in adult murine injury models by improving the clearance of dying cells. We hypothesized that exogenous administration of recombinant mouse MFG-E8 could inhibit the exaggerated inflammatory response and lung injury in a murine model of neonatal sepsis. METHODS: Neonatal sepsis was induced in 5- to 7-day-old male and female C57BL6 mice using an intraperitoneal injection of cecal slurry. At 1 hour after sepsis induction, a single dose of 40 µg/kg recombinant mouse MFG-E8 or vehicle was administered via retro-orbital injection. All neonates were returned to their mothers as a group. At 10 hours after cecal slurry injection, pups were killed and blood and lung tissues were collected. Control mice underwent a similar procedure with the exception of cecal slurry intraperitoneal injection. RESULTS: Serum lactate dehydrogenase, IL-1ß, and IL-6 were significantly increased 10 hours after cecal slurry injection. Treatment with recombinant mouse MFG-E8 decreased these levels by 30%, 56%, and 37%, respectively. Lung morphology was significantly compromised in the vehicle group after cecal slurry injection, whereas the recombinant mouse MFG-E8-treated groups demonstrated a 48% improvement in the lung injury score. Lung IL-6 and MIP-2 protein levels were significantly reduced with recombinant mouse MFG-E8 treatment. Lung neutrophil infiltration as observed by Gr-1 staining and, TUNEL-positive cells were also significantly reduced with recombinant mouse MFG-E8 treatment. CONCLUSION: Treatment with recombinant mouse MFG-E8 attenuated inflammation and lung injury in murine neonatal sepsis. Thus, MFG-E8 could be developed as a possible therapy for neonatal sepsis.

Deficiency in milk fat globule-epidermal growth factor-factor 8 exacerbates organ injury and mortality in neonatal sepsis.

INTRODUCTION: Neonatal sepsis is a systemic inflammation occurring in neonates because of a proven infection within the first 28days of birth. It is the third leading cause of morbidity and mortality in the newborns. The mechanism(s) underlying the systemic inflammation in neonatal sepsis has not been completely understood. We hypothesize that the deficiency of milk fat globule-epidermal growth factor-factor 8 (MFG-E8), a protein commonly found in human milk, could be responsible for the increased inflammatory response leading to morbidity and mortality in neonatal sepsis. METHODS: Male and female newborn mice aged 5-7days were injected intraperitoneally with 0.9mg/g body weight cecal slurry (CS). At 10h after CS injection, they were euthanized, and blood, lungs and gut tissues were obtained for further analyses. Control newborn mice underwent similar procedures with the exception of the CS injection. In duplicate newborn mice after CS injection, they were returned to their respective cages with their mothers and were closely monitored for 7days and survival rate recorded. RESULTS: At 10h after CS injection, serum LDH in the MFG-E8 knockout (KO) newborn mice was significantly increased by 58% and serum IL-6, IL-1ß and TNF-α in the MFG-E8KO newborn mice were also significantly increased by 56%, 65%, and 105%, respectively, from wild type (WT) newborn mice. There were no significant difference between WT control and MFG-E8 control newborn mice. The lung architecture was severely damaged and a significant 162% increase in injury score was observed in the CS MFG-E8KO newborn mice. The MPO, TUNEL staining, and cytokine levels in the lungs and the intestine in CS MFG-E8KO newborn mice were significantly increased from CS WT newborn mice. Similarly, intestinal integrity was also compromised in the CS MFG-E8KO newborn mice. In a survival study, while the mortality rate within 7days was only 29% in the CS WT newborn mice, 80% of the CS MFG-E8KO newborn mice died during the same time period with the majority of mortality occurring within 48h. CONCLUSION: The deficiency in MFG-E8 caused increases in inflammation, tissue injury, neutrophil infiltration and apoptosis, which led to morbidity and mortality in murine neonatal sepsis. These studies suggest that MFG-E8 has a protective role in fighting against neonatal sepsis.

Trends in the Diagnosis and Management of Pediatric Appendicitis.

• On the basis of class B evidence and consensus, acute appendicitis in children can often be diagnosed clinically with only selective use of imaging. (13)(14)(15)(16) • On the basis of class B evidence and consensus, ultrasonography is the test of choice when acute appendicitis is suspected but is unclear based on history, physical examination, and laboratory results. (17)(18)(19) • On the basis of class B evidence and consensus, the use of computed tomography scan should be limited to cases of suspected complex appendicitis with abscess or when there is clinical suspicion for acute appendicitis but ultrasonography results are not helpful. (16) • On the basis of class C evidence and consensus, children with possible appendicitis ideally should be treated in medical centers that have skilled sonographic personnel. (21) • On the basis of class B evidence and consensus, simple appendicitis should be treated by appendectomy during normal operating hours. Preoperative treatment with intravenous antibiotics and fluids during the overnight hours halts disease progression and allows for the safest surgery with the benefit of a full and rested staff. (24)(25)(26) • On the basis of class B evidence and consensus, complex appendicitis with a well-defined abscess can be treated nonoperatively initially, with the option of an interval appendectomy after recovery from the acute infection. (29)(30) (31)(32)(33)

SIRTUIN 1 ACTIVATOR SRT1720 PROTECTS AGAINST ORGAN INJURY INDUCED BY INTESTINAL ISCHEMIA-REPERFUSION.

Intestinal ischemia-reperfusion (I/R) occurs in various clinical situations and causes local and remote organ injury, especially in the lungs, leading to significant morbidity and mortality. The maintenance of mitochondrial biogenesis is essential for cell survival and is regulated in part by sirtuin 1 (SIRT1), an energy-sensing enzyme. We hypothesized that SIRT1 activation with SRT1720 would reduce local and remote organ injury after intestinal I/R. Intestinal I/R was induced by the occlusion of the superior mesenteric artery of adult male C57BL/6 mice for 45 min, followed by reperfusion for 4 h. SRT1720 or vehicle was injected intravenously at the time of reperfusion. Blood, small intestine, and lung tissues were collected for analysis. The SRT1720 treatment of I/R mice resulted in a 57% increase in protein levels of succinate dehydrogenase, an index of mitochondrial mass, and a 120% increase in messenger RNA levels of mitochondrial transcription factor A, a marker for mitochondrial biogenesis. The microscopic architecture and apoptosis of the gut tissue was improved in the SRT1720-treated I/R mice. SRT1720 decreased intestinal messenger RNA levels of tumor necrosis factor-α by 60% and inducible nitric oxide synthase to baseline after I/R. Systemic inflammation, as determined by serum interleukin-6, was reduced in treated mice. Lung injury, as measured by histological architecture and myeloperoxidase activity, and lung apoptosis were also improved after the SRT1720 treatment. SRT1720 preserved mitochondrial biogenesis and mass, leading to inhibition of inflammation and oxidative stress, thereby protecting against intestinal I/R-induced injury. Thus, the SIRT1-mediated pathway is a promising target for the treatment of intestinal I/R injury.