Antibiotic-Induced Pathobiont Dissemination Accelerates Mortality in Severe Experimental Pancreatitis.

Although antibiotic-induced dysbiosis has been demonstrated to exacerbate intestinal inflammation, it has been suggested that antibiotic prophylaxis may be beneficial in certain clinical conditions such as acute pancreatitis (AP). However, whether broad-spectrum antibiotics, such as meropenem, influence the dissemination of multidrug-resistant (MDR) bacteria during severe AP has not been addressed. In the currently study, a mouse model of obstructive severe AP was employed to investigate the effects of pretreatment with meropenem on bacteria spreading and disease outcome. As expected, animals subjected to biliopancreatic duct obstruction developed severe AP. Surprisingly, pretreatment with meropenem accelerated the mortality of AP mice (survival median of 2 days) when compared to saline-pretreated AP mice (survival median of 7 days). Early mortality was associated with the translocation of MDR strains, mainly Enterococcus gallinarum into the blood stream. Induction of AP in mice with guts that were enriched with E. gallinarum recapitulated the increased mortality rate observed in the meropenem-pretreated AP mice. Furthermore, naïve mice challenged with a mouse or a clinical strain of E. gallinarum succumbed to infection through a mechanism involving toll-like receptor-2. These results confirm that broad-spectrum antibiotics may lead to indirect detrimental effects during inflammatory disease and reveal an intestinal pathobiont that is associated with the meropenem pretreatment during obstructive AP in mice.

α1-Acid glycoprotein decreases neutrophil migration and increases susceptibility to sepsis in diabetic mice.

The mechanisms underlying immune deficiency in diabetes are largely unknown. In the present study, we demonstrate that diabetic mice are highly susceptible to polymicrobial sepsis due to reduction in rolling, adhesion, and migration of leukocytes to the focus of infection. In addition, after sepsis induction, CXCR2 was strongly downregulated in neutrophils from diabetic mice compared with nondiabetic mice. Furthermore, CXCR2 downregulation was associated with increased G-protein-coupled receptor kinase 2 (GRK2) expression in these cells. Different from nondiabetic mice, diabetic animals submitted to mild sepsis displayed a significant augment in α1-acid glycoprotein (AGP) hepatic mRNA expression and serum protein levels. Administration of AGP in nondiabetic mice subjected to mild sepsis inhibited the neutrophil migration to the focus of infection, as well as induced l-selectin shedding and rise in CD11b of blood neutrophils. Insulin treatment of diabetic mice reduced mortality rate, prevented the failure of neutrophil migration, impaired GRK2-mediated CXCR2 downregulation, and decreased the generation of AGP. Finally, administration of AGP abolished the effect of insulin treatment in diabetic mice. Together, these data suggest that AGP may be involved in reduction of neutrophil migration and increased susceptibility to sepsis in diabetic mice.

The effect of n-acetylcysteine and deferoxamine on exercise-induced oxidative damage in striatum and hippocampus of mice.

The aim of this study was to analyze the effects of intense exercise on brain redox status, associated with antioxidant supplementation of N-acetylcysteine (NAC), deferoxamine (DFX) or a combination of both. Seventy-two C57BL-6 adult male mice were randomly assigned to 8 groups: control, NAC, DFX, NAC plus DFX, exercise, exercise with NAC, exercise with DFX, and exercise with NAC plus DFX. They were given antioxidant supplementation, exercise training on a treadmill for 12 weeks, and sacrificed 48 h after the last exercise session. Training significantly increased (P < 0.05) soleus citrate synthase (CS) activity when compared to control. Blood lactate levels classified the exercise as intense. Exercise significantly increased (P < 0.05) oxidation of biomolecules and superoxide dismutase activity in striatum and hippocampus. Training significantly increased (P < 0.05) catalase activity in striatum. NAC and DFX supplementation significantly protected (P < 0.05) against oxidative damage. These results indicate intense exercise as oxidant and NAC and DFX as antioxidant to the hippocampus and the striatum.

Attenuation of bleomycin-induced lung injury and oxidative stress by N-acetylcysteine plus deferoxamine.

Reactive oxygen species (ROS) play an important role in the pathogenesis of pulmonary injury and antioxidant therapy may be useful with impaired oxidative defense mechanism. This study examines the effect of N-acetylcysteine (NAC) and deferoxamine (DFX) on inflammatory indicators and oxidative stress in the lungs of mice exposed to bleomycin (BLM). The animals received endotracheally a single dose of BLM (2.5 U/kg body weight dissolved in 0.25 ml of 0.9% NaCl) or saline (0.9% NaCl) and were divided into eight groups (n=8): saline; BLM; saline+NAC; BLM+NAC; saline+DFX; BLM+DFX; saline+NAC+DFX; BLM+NAC+DFX. Treatments with NAC (20mg/kg) or DFX (30 mg/kg) were administered for 60 days after BLM exposure. Lactate dehydrogenase (LDH) activity and total cell count, neutrophil and protein concentration were determined in the bronchoalveolar lavage fluid (BALF). Lipid peroxidation thiobarbituric acid-reactive species (TBARS), oxidative protein damage (carbonyl contents), and catalase and superoxide dismutase activities were determined in the lung tissue. BLM administration resulted in lung lesion as determinated lung histology, which is almost completely prevented by NAC plus DFX. The results of total cell counts and neutrophils and LDH increased after BLM exposure and were reduced with NAC. DFX and NAC plus DFX also caused a significant decrease of LDH activity. The increased malondialdehyde equivalents and carbonyl contents in lung tissue produced by BLM were also prevented by NAC plus DFX. However, the isolated use of NAC increased lipid peroxidation. SOD activity increased after BLM exposure only in the group treated with DFX and catalase activity not was altered in the presence of BLM. Data presented here indicates that the isolated use of NAC had limited effects on BLM-induced pulmonary oxidative stress in mice. The use of DFX improves the defense response and in association with NAC may be a good alternative in the treatment or prevention of diseases that have ROS and iron involved in their pathogenesis.