The mechanism underlying the appearance of late apoptotic neutrophils and subsequent TNF-α production at a late stage during Staphylococcus aureus bioparticle-induced peritoneal inflammation in inducible NO synthase-deficient mice

Two Alkaloids From Delphinium brunonianum Royle, Their Anti-inflammatory and Anti-oxidative Stress Activity via NF-κB Signaling Pathway

In this study, we isolated and identified four compounds in Delphinium brunonianum Royle, and they were Delbrunine (1), 4-O-α-D-Glucosyl benzoic acid (2), Kaempferol 3-O-β-D-glucopyranoside 7-O-α-L-rhamnopyranoside (3) and Eldeline (4). Furthermore, the anti-inflammatory activity of these compounds was screened in RAW264.7 cells. The results showed that the anti-inflammatory activities of compounds 2 and 3 were weak, and 1, 4 had good anti-inflammatory activity. The macrophage inflammation model was established by lipopolysaccharide (LPS). Then, the anti-inflammatory activity was evaluated by ELISA kits, qRT-PCR experiment and western blot experiment. And the anti-oxidative stress activity was assessed by flow cytometry. The results showed that compounds 1, 4 could significantly inhibit the elevation of inflammatory factors nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and also had obvious inhibitory effects on the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2). In addition, compounds 1 and 4 could effectively inhibit the overexpression of reactive oxygen species (ROS) in RAW264.7 cells that activated by LPS. These results indicated that compounds 1 and 4 may exert anti-inflammatory and anti-oxidative stress effects through the NF-κB signaling pathway.

Interleukin-1β and tumor necrosis factor are essential in controlling an experimental orthopedic implant-associated infection

Orthopedic implant-associated infection (OIAI) is a major complication that leads to implant failure. In preclinical models of Staphylococcus aureus OIAI, osteomyelitis and septic arthritis, interleukin-1α (IL-1α), IL-1β, and tumor necrosis factor (TNF) are induced, but whether they have interactive or distinctive roles in host defense are unclear. Herein, a S. aureus OIAI model was performed in mice deficient in IL-1α, IL-1β, or TNF. Mice deficient in IL-1β or TNF (to a lesser extent) but not IL-1α had increased bacterial burden at the site of the OIAI throughout the 28-day experiment. IL-1β and TNF had a combined and critical role in host defense as mice deficient in both IL-1R and TNF (IL-1R/TNF-deficient mice) had a 40% mortality rate, which was associated with markedly increased bacterial burden at the site of the OIAI infection. Finally, IL-1α- and IL-1β-deficient mice had impaired neutrophil recruitment whereas IL-1β-, TNF-, and IL-1R/TNF-deficient mice all had impaired recruitment of both neutrophils and monocytes. Therefore, IL-1β and TNF contributed to host defense against S. aureus OIAI and neutrophil recruitment was primarily mediated by IL-1β and monocyte recruitment was mediated by both IL-1β and TNF.

Changes in the function and phenotype of resident peritoneal macrophages after housing in an enriched environment

Exposure to an enriched environment (EE) affects not only brain functions but also immune responses upon viral or bacterial infections. In this study, we examined changes in the phagocytic response and chemokine production of resident peritoneal macrophages after mice had been housed under EE conditions for 6 or 8 weeks, and then explored the possibility that EE could cause a change in the macrophage phenotype by means of flow cytometry as well as quantitative RT-PCR. The percentages of EE macrophages phagocytosing S. aureus and apoptotic neutrophils were significantly larger than those of standard environment (SE) macrophages. After coculturing with S. aureus, EE macrophages tended to produce greater amounts of chemokines such as MIP-2, KC and MCP-1 than SE ones, although the increases for MIP-2 and KC were not statistically significant. As compared with SE macrophages, EE macrophages included more CD40-positive cells (M1 marker), and expressed more mRNAs of IL-6 (M1 marker) and IRF4 (M2 marker), and less mRNA of CD38 (M1 marker), suggesting either the possibility that EE macrophages are a mixed population of M1 and M2 macrophages or the possibility that they are a unique population with a mixed M1 and M2 macrophage phenotype.

Nitric oxide-mediated apoptosis of neutrophils through caspase-8 and caspase-3-dependent mechanism

Neutrophils play an indispensable role in killing of invading pathogens by enhancing reactive oxygen species (ROS) and NO generation, and subsequently undergoing apoptosis. Unlike ROS/NOX2, role of NO/NOS still remains undefined in the apoptosis of neutrophils (PMNs) and the present study attempts to decipher the importance of NO/NOS in the neutrophil apoptosis. Prolonged treatment of human PMNs or mice bone marrow derived neutrophils (BMDN) with NO led to enhanced ROS generation, caspase-8/caspase-3 cleavage, reduced mitochondrial membrane potential and finally cellular apoptosis. NO-induced ROS generation led to caspase-8 deglutathionylation and activation, which subsequently activated mitochondrial death pathway via BID (Bcl-2 family protein) cleavage. NO-mediated augmentation of caspase-8 and BID cleavage was significantly prevented in BMDN from neutrophil cytosolic factor-1 (NCF-1) knockout (KO) mice, implying the involvement of NOX2 in NO-induced apoptosis of PMNs. Furthermore, ROS, NO generation and inducible nitric oxide synthase (iNOS) expression were enhanced in a time-dependent manner in human PMNs and mice BMDN undergoing spontaneous apoptosis. Pharmacological and genetic ablation of iNOS in human PMNs and mice BMDN significantly reduced the levels of apoptosis. Impaired apoptosis of BMDN from iNOS KO mice was due to reduced caspase-8 activity which subsequently prevented caspase-3 and -9 activation. Altogether, our results suggest a crucial role of NO/iNOS in neutrophil apoptosis via enhanced ROS generation and caspase-8 mediated activation of mitochondrial death pathway.

Topical antimicrobial photodynamic therapy improves angiogenesis in wounds of diabetic mice

We report the results of our investigations on the effect of antimicrobial photodynamic therapy (APDT) on angiogenesis in wounds of diabetic mice. For this, measurements were made on levels of nitric oxide (NO), vascular endothelial growth factor-A (VEGF-A), and markers of proinflammatory stress (phosphorylated nuclear factor kappa B and p(38) mitogen-activated protein kinase) on day 3 post-wounding. For uninfected and infected wounds, the levels of NO, VEGF-A were lower and the levels of phospho-NF-kB-p65, phospho-p(38)MAPK were higher in diabetic mice compared with that in nondiabetic mice. For infected wounds, multiple APDT (fluence ~60 J/cm(2)) led to increase in NO, VEGF-A levels and a decrease in the phospho-NF-kB-p65, phospho-p(38)MAPK. Further, compared with aminoguanidine, and silver nitrate, multiple APDT was observed to result in a much improved proangiogenic response.