No Short-Term Effect of Low-Dose Nicotine on Inflammation after Global Hypoxia in Newborn Piglets.

INTRODUCTION: Perinatal asphyxia initiates cytokine release and complement activation with risk of brain damage. We assessed the effect of nicotine on innate immunity and hypothesized that nicotine infusion in a newborn piglet model of asphyxia would decrease the immune response and be neuroprotective. METHODS: Newborn piglets (n = 41) were randomized to one of three groups after hypoxia: two groups receiving nicotine, (1) 18 µg/kg/h (n = 17), (2) 46 µg/kg/h (n = 15), and (3) control group receiving saline (n = 9). C3a, IL-6, TNF, and IL-10 were measured in plasma and IL-6 and IL-8 in microdialysis fluid from cerebral periventricular white matter, using immuno-assays. RESULTS: Plasma C3a and IL-6 increased significantly from start to end hypoxia (mean 4.4 ± 0.55 to 5.6 ± 0.71 ng/mL and 1.66 ± 1.04 to 2.68 ± 0.71 pg/mL, respectively), while IL-10 and TNF increased significantly after 4 h (mean 1.4 ± 1.08 to 2.9 ± 1.87 and 3.3 ± 0.67 to 4.0 ± 0.58 pg/mL, respectively) (p < 0.001 for all). IL-6 increased significantly (p < 0.001) in microdialysis samples from end hypoxia to end experiment (mean 0.65 ± 0.88 to 2.78 ± 1.84 ng/mL). No significant differences were observed between the nicotine groups and the control group neither in plasma nor in microdialysis samples. CONCLUSION: Hypoxia leads to rapid release of cytokines in plasma and cerebral microdialysis fluid, and complement activation measured on C3a. However, low-dose nicotine administration did not affect the immune response.

Simultaneous C5 and CD14 inhibition limits inflammation and organ dysfunction in pig polytrauma.

Dysfunctional complement activation and Toll-like receptor signaling immediately after trauma are associated with development of trauma-induced coagulopathy and multiple organ dysfunction syndrome. We assessed the efficacy of the combined inhibition therapy of complement factor C5 and the TLR co-receptor CD14 on thrombo-inflammation and organ damage in an exploratory 72-h polytrauma porcine model, conducted under standard surgical and intensive care management procedures. Twelve male pigs were subjected to polytrauma, followed by resuscitation (ATLS® guidelines) and operation of the femur fracture (intramedullary nailing technique). The pigs were allocated to combined C5 and CD14 inhibition therapy group (n=4) and control group (n=8). The therapy group received intravenously C5 inhibitor (RA101295) and anti-CD14 antibody (rMil2) 30 min post-trauma. Controls received saline. Combined C5 and CD14 inhibition reduced the blood levels of the terminal complement complex (TCC) by 70% (p=0.004), CRP by 28% (p=0.004), and IL-6 by 52% (p=0.048). The inhibition therapy prevented the platelet consumption by 18% and TAT formation by 77% (p=0.008). Moreover, the norepinephrine requirements in the treated group were reduced by 88%. The inhibition therapy limited the organ damage, thereby reducing the blood lipase values by 50% (p=0.028), LDH by 30% (p=0.004), AST by 33%, and NGAL by 30%. Immunofluorescent analysis of the lung tissue revealed C5b-9 deposition on blood vessels in five from the untreated, and in none of the treated animals. In kidney and liver, the C5b-9 deposition was similarly detected mainly the untreated as compared to the treated animals. Combined C5 and CD14 inhibition limited the inflammatory response, the organ damage, and reduced the catecholamine requirements after experimental polytrauma and might be a promising therapeutic approach.

Staphylococcus aureus Membrane-Derived Vesicles Promote Bacterial Virulence and Confer Protective Immunity in Murine Infection Models.

Staphylococcus aureus produces membrane-derived vesicles (MVs), which share functional properties to outer membrane vesicles. Atomic force microscopy revealed that S. aureus-derived MVs are associated with the bacterial surface or released into the surrounding environment depending on bacterial growth conditions. By using a comparative proteomic approach, a total of 131 and 617 proteins were identified in MVs isolated from S. aureus grown in Luria-Bertani and brain-heart infusion broth, respectively. Purified S. aureus MVs derived from the bacteria grown in either media induced comparable levels of cytotoxicity and neutrophil-activation. Administration of exogenous MVs increased the resistance of S. aureus to killing by whole blood or purified human neutrophils ex vivo and increased S. aureus survival in vivo. Finally, immunization of mice with S. aureus-derived MVs induced production of IgM, total IgG, IgG1, IgG2a, and IgG2b resulting in protection against subcutaneous and systemic S. aureus infection. Collectively, our results suggest S. aureus MVs can influence bacterial-host interactions during systemic infections and provide protective immunity in murine models of infection.