The Pseudomonas aeruginosa virulence factor Cif inhibits the generation of the pro-resolving lipid mediator 15-epi lipoxin A4 (MPF3P.812)

Pseudomonas aeruginosa is an opportunistic Gram-negative bacteria that causes a wide range of severe nosocomial infections, especially in immunocompromised patients with chronic inflammatory lung disease. P. aeruginosa infections are characterized by persistent and robust neutrophilic inflammation which can cause damage to host tissue. Lipoxins, including 15-epi-lipoxin A4 (15-epi-LXA4), are lipid mediators that play a critical role in resolving inflammation and promoting tissue homeostasis. The production of 14,15-epoxy-eicosatrienoic acid (14,15-EET) by airway epithelial cells stimulates the generation of 15-epi-LXA4 by neighboring neutrophils through transcellular biosynthesis. We have identified a P. aeruginosa virulence factor with epoxide hydrolase activity called cystic fibrosis inhibitory factor (Cif), which we hypothesize disrupts the generation of 15-epi-LXA4. We show that both P. aeruginosa and recombinant Cif protein alone hydrolyzes the epoxide moiety of (14,15-EET), whereas a Cif mutant P. aeruginosa or catalytically dead D129S mutant of Cif have no effect. Furthermore, the Cif-mediated reduction of 14,15-EET inhibited the generation of 15-epi-LXA4 by activated neutrophils in vitro. The D129S mutant Cif was also incapable of reducing 15-epi-LXA4 biosynthesis. Taken together, our data suggest a novel model whereby the P. aeruginosa virulence factor Cif reduces 15-epi-LXA4 in the airways, thus promoting persistent inflammation and consequent lung damage.

Abstract C59: Estradiol and mTORC2 orchestrate to enhance prostaglandin biosynthesis andtumorigenesis in tuberous sclerosis complex

Lymphangioleiomyomatosis (LAM) is a female predominant progressive and neoplastic disorder that leads to lung destruction and respiratory failure primarily in women. LAM is typically due to TSC2 mutations resulting in mTORC1 activation in proliferative smooth muscle-like cells in the lung. The female predominance of LAM suggests that estradiol contributes to disease development. Metabolomic profiling identified estradiol-enhanced prostaglandin biosynthesis signature in Tsc2-deficient cells, both in vitro and in vivo. Estradiol increased the expression of cyclooxygenase-2 (COX-2), a rate-limiting enzyme in prostaglandin biosynthesis, which was increased at baseline in TSC2-deficient cells, and was not affected by rapamycin treatment, but decreased by Torin 1 treatment and Rictor knockdown, associated with reduction of levels phospho-Akt (S473). Prostaglandin production was also increased in TSC2-deficient cells. In preclinical models, Celecoxib or aspirin treatment suppressed tumor progression. LAM patients had significantly higher

serum prostaglandin levels than healthy women. 15-epi-lipoxin-A4 was identified in exhaled breath condensate from LAM subjects and was increased by aspirin treatment, indicative of functional COX-2 expression in the LAM airway. Targeting COX-2 and prostaglandin pathways may have therapeutic value in LAM and TSC-related diseases, and possibly in other conditions associated with mTOR-hyperactivation.

Citation Format: Chenggang Li, Po-Shun Lee, Xiaoxiao Gu, Yang Sun, Erik Zhang, Alfredo Csibi, Jing Li, Carmen Priolo, Yanan Guo, Chin-Lee Wu, John Blenis, Kai-Feng Xu, Elizabeth Petri Henske, Bruce Levy, David Kwiatkowski, Jane J. Yu. Estradiol and mTORC2 orchestrate to enhance prostaglandin biosynthesis andtumorigenesis in tuberous sclerosis complex. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr C59.

Lactate or ScvO2 as an endpoint in resuscitation of shock states?

In the current management of critically ill patients, variables such as blood pressure, urine output or central venous pressure guide resuscitative efforts. Unfortunately, global tissue hypoxia may persist leading to multiple organ failure and death. To address tissue well-being, indices such as central venous oxygen saturation (ScvO2) and Lactatemia are widely used and are strongly linked to outcome. Implementing these indices in haemodynamic optimization protocols have been shown to reduce morbidity and mortality in numerous studies especially in septic shock. Nevertheless, choosing one index over the other remains controversial. Herein, we review the physiology and rationale for ScvO2 and lactate monitoring. Clinical uses, evidence-based outcome implications and limitations are also examined to aid the clinician in daily practice.

LACTATE or ScvO2 as an endpoint in resuscitation of shock states?

In the current management of critically ill patients, variables such as blood pressure, urine output or central venous pressure guide resuscitative efforts. Unfortunately, global tissue hypoxia may persist leading to multiple organ failure and death. To address tissue well-being, indices such as central venous oxygen saturation (ScvO2) and lactataemia are widely used and are strongly linked to outcome. Implementing these indices in haemodynamic optimization protocols have been shown to reduce morbidity and mortality in numerous studies especially in septic shock. Nevertheless, choosing one index over the other remains controversial. Herein, we review the physiology and rationale for ScvO2 and lactate monitoring. Clinical uses, evidence-based outcome implications and limitations are also examined to aid the clinician in daily practice. Key words: lactate, central venous oxygen saturation, shock, goal-directed therapy.

Femoral tunnel malposition in ACL revision reconstruction

The Multicenter Anterior Cruciate Ligament (ACL) Revision Study (MARS) group was formed to study a large cohort of revision ACL reconstruction patients. The purpose of this subset analysis study of the MARS database is to describe specific details of femoral tunnel malposition and subsequent management strategies that surgeons chose in the revision setting. The design of this study is a case series. The multicenter MARS database is compiled from a questionnaire regarding 460 ACL reconstruction revision cases returned by 87 surgeons. This subset analysis described technical aspects and operative findings in specifically those cases in which femoral tunnel malposition was cited as the cause of primary ACL reconstruction failure. Of the 460 revisions included for study, 276 (60%) cases cited a specific "technical cause of failure." Femoral tunnel malposition was cited in 219 (47.6%) of 460 cases. Femoral tunnel malposition was cited as the only cause of failure in 117 cases (25.4%). Surgeons judged the femoral tunnel too vertical in 42 cases (35.9%), too anterior in 35 cases (29.9%), and too vertical and anterior in 31 cases (26.5%). Revision reconstruction involved the drilling of an entirely new femoral tunnel in 91 cases (82.1%). For primary reconstruction, autograft tissue was used in 82 cases (70.1%). For revision reconstruction, autograft tissue was used in 61 cases (52.1%) and allograft tissue in 56 cases (47.9%). Femoral tunnel malposition in primary ACL reconstruction was the most commonly cited reason for graft failure in this cohort. Graft selection is widely variable among surgeons.

[The impact of early cranioplasty on cerebral blood flow and its correlation with neurological and cognitive outcome. Prospective multi-centre study on 24 patients]

INTRODUCTION

Cranioplasty after decompressive craniectomy in patients suffering from severe head injury often leads to a functional improvement although, to date, the pathophysiology of this phenomenon remains unclear. A few hypotheses have been proposed. The impact of cranioplasty on cerebral perfusion could be one explanation. We have evaluated the impact of cranioplasty on the functional status of patients undergoing decompressive craniectomy for severe head injury with its influence on cerebral perfusion.

MATERIALS AND METHODS

Twenty-four patients undergoing craniectomy for severe head injury were included in this multi-centric and prospective study. All of them had a cranioplasty within 12 weeks following decompressive craniectomy. A clinical and radiological evaluation was performed prior to and after cranioplasty. Neurological and cognitive evaluation was performed with the Glasgow Outcome Score (GOS), the Frontal Assessment Battery (FAB) and the Mini Mental State Examination (MMSE). Radiological evaluation was performed by perfusion CT scan and transcranial Doppler.

RESULTS

A statistically significant neurological and cognitive improvement was observed in 92% of patients at 6 months follow-up (F-U). Brain perfusion was improved at 6 weeks F-U, predominantly in the affected hemisphere. Systolic and diastolic blood velocity flow were improved in both middle cerebral arteries.

CONCLUSION

Cranioplasty after decompressive craniectomy for patients suffering from severe head injury probably improves the functional outcome of these patients, thanks to a global improvement of cerebral perfusion.