Current Trends of Neutrophil Biology.

Neutrophils are short-lived and terminally differentiated cells, and therefore, have been considered as effector cells to phagocytose pathogens and kill them or damage tissues [...].

Age-related dysfunction of p53-regulated phagocytic activity in macrophages.

Aging promotes polarization of M2-like macrophages to M1-like macrophages and reduces their phagocytic ability. However, the molecular mechanisms underlying these aging-related changes remain poorly understood. Here, we demonstrate that p53 regulates phagocytic activity in macrophages from young mice but not in those from old ones. Macrophages from both old and young mice expressed functional p53 to induce target genes including p21 and Mdm2. In macrophages from young mice, chemically induced p53 decreased phagocytic activity and c-Myc levels, with the latter change reducing M2-related genes. However, in macrophages from old mice, phagocytic activity and c-Myc expression were independent of p53 activity. Furthermore, c-Myc suppression did not affect M2-related genes in old-mouse macrophages. These results demonstrate that dysregulation of p53 function is a molecular mechanism underlying reduced phagocytic activity in aged-mouse macrophages.

Kinetics of cytokine mRNA and protein expression by plastic adherent cells in the thymus after split-dose irradiation.

Whole body irradiation causes significant apoptosis in various tissues such as the thymus. If apoptotic cells outnumber the phagocytic capacity of macrophages, apoptosis becomes secondary necrosis, inducing inflammatory cytokine expression in macrophages. Radiation also induces thymic lymphomas in C57BL/6 mice after four consecutive irradiations with 1.6 Gy X-rays with nearly 100% incidence. Since cancer development is modulated by a microenvironment involving macrophages, we examined the kinetics of thymocyte number and plastic adherent cell number in the thymus as well as cytokine mRNA expression by plastic adherent cells in the thymus after split-dose irradiation. Upon split-dose irradiation, thymocyte number changed dramatically, whereas plastic adherent cell number did not. Among cytokine mRNAs tested, IL-1ß, IL-11 and IL-12p40 mRNAs were up regulated 2 days after the 1st and 2nd, 3rd and 4th, and 2nd and 3rd irradiations, respectively. On the other hand, TNF-α mRNA was up regulated 2 days after the 3rd irradiation and 2 weeks after the 4th irradiation. The level of IL-11 protein was also increased 2 days after 3rd and 4th irradiations. These results suggest that, upon split-dose irradiation, macrophages in the thymus produce various cytokines in a time-dependent manner, thereby contributing to induction of thymic lymphomas.

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.

Potential roles of DNA methylation in the initiation and establishment of replicative senescence revealed by array-based methylome and transcriptome analyses.

Cellular senescence is classified into two groups: replicative and premature senescence. Gene expression and epigenetic changes are reported to differ between these two groups and cell types. Normal human diploid fibroblast TIG-3 cells have often been used in cellular senescence research; however, their epigenetic profiles are still not fully understood. To elucidate how cellular senescence is epigenetically regulated in TIG-3 cells, we analyzed the gene expression and DNA methylation profiles of three types of senescent cells, namely, replicatively senescent, ras-induced senescent (RIS), and non-permissive temperature-induced senescent SVts8 cells, using gene expression and DNA methylation microarrays. The expression of genes involved in the cell cycle and immune response was commonly either down- or up-regulated in the three types of senescent cells, respectively. The altered DNA methylation patterns were observed in replicatively senescent cells, but not in prematurely senescent cells. Interestingly, hypomethylated CpG sites detected on non-CpG island regions ("open sea") were enriched in immune response-related genes that had non-CpG island promoters. The integrated analysis of gene expression and methylation in replicatively senescent cells demonstrated that differentially expressed 867 genes, including cell cycle- and immune response-related genes, were associated with DNA methylation changes in CpG sites close to the transcription start sites (TSSs). Furthermore, several miRNAs regulated in part through DNA methylation were found to affect the expression of their targeted genes. Taken together, these results indicate that the epigenetic changes of DNA methylation regulate the expression of a certain portion of genes and partly contribute to the introduction and establishment of replicative senescence.

Impact of Left Heart Bypass on Arterial Oxygenation During One-Lung Ventilation for Thoracic Aortic Surgery.

OBJECTIVE: The aim of this study was to reveal the mechanism of improved arterial oxygenation by measuring the changes in oxygenation before and after initiation of left heart bypass (LHB) during one-lung ventilation (OLV) for thoracic aortic surgery. DESIGN: Prospective, observational study. SETTING: Single-institution, private hospital. PARTICIPANTS: The study comprised 50 patients who underwent aortic surgery via a left thoracotomy approach with LHB circulatory support. INTERVENTIONS: Patients were ventilated using pure oxygen during OLV, and the ventilator setting was left unchanged during the measurement period. MEASUREMENTS AND MAIN RESULTS: The measurement of partial pressure of arterial oxygen (PaO2) was made at the following 4 time points: 2 minutes after heparin infusion (point 1 [P1]), 2 minutes after inflow cannula insertion through the left pulmonary vein (P2), immediately before LHB initiation (P3), and 10 minutes after LHB initiation (P4). The mean±standard deviation (mmHg) of PaO2 measurements at the P1, P2, P3, and P4 time points were 244±121, 250±123, 419±122, and 430±109, respectively, with significant increases between P1 and P3, P1 and P4, P2 and P3, and P2 and P4 (p<0.0001, respectively). No significant increase in PaO2 was seen between P1 and P2 or between P3 and P4. CONCLUSIONS: The improved arterial oxygenation during OLV in patients who underwent thoracic aortic surgery using LHB can be attributed to the insertion of an inflow cannula via the left pulmonary vein into the left atrium before LHB.

Endovascular repair with extracorporeal membrane oxygenation as a rescue strategy for aortobronchial fistula: a case report.

Aortobronchial fistula (ABF) is a rare and potentially lethal complication of thoracic aortic replacement surgery. Currently, thoracic endovascular aortic repair (TEVAR) has emerged as a less invasive alternative to open surgery for ABF to facilitate prompt hemostasis. However, there are no published reports of TEVAR for ABF, particularly for presentation with life-threatening respiratory failure from massive hemoptysis. A 48-year-old male patient, who had recently undergone aortic root and arch replacement due to aortic dissection, was transferred to the emergency department with massive hemoptysis and severe dyspnea. A single-lumen endotracheal tube was immediately placed in the right main bronchus to protect the nonbleeding lung from spillage of blood. Chest computed tomography (CT) showed leakage of contrast material from the distal anastomosis of the aortic graft and consolidated lung tissue adjacent to the leakage. He was diagnosed with an ABF following aortic arch replacement, and an emergency TEVAR was performed. After adequate hemostasis, severe hypercapnia remained uncorrected despite the maximum ventilatory support. Thus, venovenous extracorporeal membrane oxygenation (VV ECMO) was immediately initiated, and severe respiratory acidosis improved dramatically. Furthermore, VV ECMO facilitated prompt bronchoscopic washout of the remaining blood clot without any danger of respiratory collapse and was weaned off successfully after 5 days as ventilation improved. This case demonstrates that emergency TEVAR in combination with VV ECMO can be a rescue strategy for massive hemoptysis from an ABF.

Anesthetic Management of a Surgical Patient with Chronic Renal Tubular Acidosis Complicated by Subclinical Hypothyroidism.

A 53-year-old man with chronic renal tubular acidosis and subclinical hypothyroidism underwent lower leg amputation surgery under general anesthesia. Perioperative acid-base management in such patients poses many difficulties because both pathophysiologies have the potential to complicate the interpretation of capnometry and arterial blood gas analysis data; inappropriate correction of chronic metabolic acidosis may lead to postoperative respiratory deterioration. We discuss the management of perioperative acidosis in order to achieve successful weaning from mechanical ventilation and promise a complete recovery from anesthesia.

Skewing of peritoneal resident macrophages toward M1-like is involved in enhancement of inflammatory responses induced by secondary necrotic neutrophils in aged mice.

Secondary necrotic cells, which are generated if apoptotic cells are incompletely cleared, induce severe inflammatory responses involving MIP-2 production and subsequent neutrophil infiltration. Recently, we showed that the phagocytic capacity of peritoneal resident macrophages from wild type (WT) aged mice as well as SMP30(-/-) mice fed a VC-limited diet as to secondary necrotic cells was reduced as compared with that in young mice, and that the inflammatory responses induced were stronger than those in young mice, presumably because of the delay in removal of secondary necrotic cells in aged mice. In this study, we investigated why MIP-2 production was increased in aged mice upon injection of secondary necrotic cells and why the phagocytic capacity of peritoneal resident macrophages from aged mice was reduced. When cocultured with secondary necrotic cells, the peritoneal resident macrophages from both types of aged mice significantly produced MIP-2 even in the absence of IFN-γ, whereas MIP-2 production by macrophages from WT young mice required IFN-γ. The peritoneal resident macrophages from both types of aged mice expressed CD40, a M1 macrophage marker, as in the case of M1 macrophages, which were obtained by treatment of macrophages from WT young mice with IFN-γ and LPS. Furthermore, M1 macrophages exhibited less phagocytic capacity as to secondary necrotic cells than non-treated macrophages. These results suggest that the phenotype of peritoneal resident macrophages is skewed toward M1-like in aged mice and that such skewing toward M1-like is involved in enhancement of inflammatory responses induced by secondary necrotic neutrophils in aged mice.

Suppression of macrophage-mediated phagocytosis of apoptotic cells by soluble ß-glucan due to a failure of PKC-ßII translocation.

If apoptotic cells are not removed efficiently, they may proceed to the stage of secondary necrosis, which would cause inflammation. Therefore, identification of cause(s) and agent(s) for down-modulating phagocytosis of apoptotic cells would help understand the pathologies. In this study we found that macrophage-mediated phagocytosis of apoptotic cells was suppressed by both soluble and particulate ß-glucan. This suppression was not observed when secondary necrotic cells were used. The adhesion of apoptotic cells to macrophages was not suppressed by soluble ß-glucan, suggesting that soluble ß-glucan suppresses phagocytosis at a post-adhesion step. Experiments involving PKC inhibitors suggested that PKC-ßII is required for phagocytosis of apoptotic cells but not secondary necrotic ones by macrophages. Translocation of GFP-PKC-ßII from the cytoplasm to membranes occurred upon interaction with apoptotic cells but not secondary necrotic ones. Such translocation was inhibited by soluble ß-glucan. Overall, this study suggests that suppression of macrophage-mediated phagocytosis of apoptotic cells by soluble ß-glucan is due to a failure of PKC-ßII translocation.

[Hyperthyroidism Diagnosed from Refractory Tachycardia and Hypotension during Surgery: A Case Report].

We report a case of hyperthyroidism diagnosed from refractory tachycardia and hypotension during surgery. Although the patient had exhibited tachycardia preop- eratively, it was difficult to suspect hyperthyroidism due to specific conditions of neurosurgical patient Eventually diagnosis of hyperthyroidism was made by exclusion, and prompt treatment was effectively initiated. Recently several reports suggested that landiolol was effective for rate control in patients with hyperthyroidism. At first intravenous bolus doses of landiolol were administered but were insufficient Secondly, intravenous propranolol was administered and tachycardia as well as blood pressure improved. The benefits of propranolol has been suggested.

Attenuated phagocytosis of secondary necrotic neutrophils by macrophages in aged and SMP30 knockout mice.

AIM: Secondary necrotic cells generated in vivo induce inflammatory responses; for example, the production of macrophage inflammatory protein-2 (MIP-2) and subsequent infiltration of neutrophils. The aim of the present study was to elucidate the effect of aging on the phagocytosis of secondary necrotic cells and the inflammatory responses by using either wild-type (WT) young mice, WT aged mice or senescence-accelerated mice (SMP30(-/-) mice). METHODS: The phagocytosis of secondary necrotic neutrophils with resident macrophage from either WT young mice, WT aged mice or SMP30(-/-) mice was examined by coculturing macrophages with secondary necrotic neutrophils in vitro. To investigate the inflammatory response induced by secondary necrotic cells, time-dependent infiltration of neutrophils and production of MIP-2 were determined in the peritoneal cavity on the injection of secondary necrotic cells. RESULTS: The phagocytosis of secondary necrotic cells by macrophages from WT aged and SMP30(-/-) mice was significantly reduced as compared with that by macrophages from WT young mice. On peritoneal injection of secondary necrotic cells, the peak time of neutrophil infiltration was earlier in SMP30(-/-) mice than in WT young mice. The number of neutrophils in SMP30(-/-) mice at the peak time was also greater than that in WT young mice. CONCLUSIONS: Our findings showed that the phagocytosis of secondary necrotic cells was attenuated in aged mice and SMP30(-/-) mice, and that the MIP-2 production was enhanced and subsequently neutrophil infiltration was exaggerated on peritoneal injection of secondary necrotic cells into those mice.

Neutrophil biology: an update.

Neutrophil extracellular traps (NETs) are involved in bacterial killing as well as autoimmunity, because NETs contain proteases, bactericidal peptides, DNA and ribonucleoprotein. NETs are formed via a novel type of cell death called NETosis. NETosis is distinct from apoptosis, but it resembles necrosis in that both membranes are not intact so that they allow intracellular proteins to leak outside of the cells. Removal of NETs and neutrophils undergoing NETosis by phagocytes and its subsequent response are not completely clarified, as compared with the response after removal of either apoptotic or necrotic neutrophils by phagocytes. How neutrophil density in peripheral blood is kept within a certain range is important for health and disease. Although the studies on severe congenital neutropenia and benign ethnic neutropenia have provided unbiased views on it, the studies are rather limited to human neutropenia, and mice with a mutation of mouse counterpart gene often fail to exhibit neutropenia. Degranulation plays a critical role in bactericidal action. The recent studies revealed that it is also involved in immunomodulation, pain control and estrous cycle control. N1 and N2 are representative of neutrophil subpopulations. The dichotomy holds true in patients or mice with severe trauma or cancer, providing the basis of differential roles of neutrophils in diseases.

[Analgesia with paravertebral block for postoperative pain after thoracic or thoracoabdominal aortic aneurysm repair].

Paraplegia is a serious complication after thoracoabdominal aortic aneurysm repair. Therefore, maintenance of spinal cord perfusion pressure, drainage of cerebrospinal fluid, and avoidance of opioids are important for prevention of paraplegia Management of acute post-thoracotomy pain is necessary not only to keep the patient comfortable but also to minimize postoperative complications. However, epidural analgesia, a common method of pain control, is hard to use because of existing postoperative coagulopathy and avoidance of spinal cord ischemia Although both paravertebral block and epidural analgesia provide comparable pain relief after thoracic surgery, paravertebral block has lesser detrimental effects on spinal cord perfusion and better preserves the possibility to monitor neurologic function than epidural analgesia. We report 7 cases in which paravertebral blockade was used for analgesia in patients who underwent thoracoabdominal aneurysm repair.

Low levels of urinary liver-type fatty acid-binding protein may indicate a lack of kidney protection during aortic arch surgery requiring hypothermic circulatory arrest.

STUDY OBJECTIVE: To examine the change in liver-type fatty acid-binding protein (L-FABP) levels in patients undergoing aortic arch surgery and the correlation between L-FABP and postoperative acute kidney injury. DESIGN: Prospective observational study. SETTING: Operating room of a general hospital. PATIENTS: 36 adult patients. INTERVENTIONS AND MEASUREMENTS: Urine samples were obtained to measure urinary L-FABP at initiation of cardiopulmonary bypass (CPB) and 5 minutes after termination of hypothermic circulatory arrest. MAIN RESULTS: 22 (61.1%) patients developed acute kidney injury within a 48-hour period. L-FABP increases more than a thousand-fold were found. In patients who subsequently developed acute kidney injury, significant increases in L-FABP were noted from 2.9 (3.6) ng/mg of creatinine before CPB to 62.1 (995.6) ng/mg of creatinine 5 minutes after termination of circulatory arrest. Values in patients who did not develop acute kidney injury increased from 1.1 (5.7) ng/mg before CPB to 1133.0 (6358.8) ng/mg of creatinine showing a significant mean difference (P = 0.011). The area under the L-FABP receiver operating characteristic curve at 5 minutes after termination of circulatory arrest was 0.758. A cutoff value of 75.13 ng/mg of creatinine yielded both good sensitivity (1.000) and specificity (0.546) for detecting non-acute kidney injury. Patients who developed acute kidney injury after aortic arch surgery demonstrated lower levels of urinary L-FABP. CONCLUSIONS: Low levels of urinary L-FABP may indicate kidney injury and lack of renal protection.

Nonocclusive mesenteric ischemia following multiple wasp stings.

Massive wasp envenomation can cause not only severe immediate allergic reactions and anaphylaxis but also severe delayed toxin-mediated systemic reactions, including hemolysis, coagulopathy, rhabdomyolysis, acute renal failure, and hepatotoxicity. However, reports of the latter type of reactions are rare. The subject of this case report, a 66-year-old man, was stung more than 30 times during an attack by wasps. Although he initially complained of pain, he showed no signs of anaphylaxis during observation in an emergency department. Twenty hours after envenomation, he was admitted to the hospital because of vomiting, abdominal pain, and lower gastrointestinal bleeding. Mesenteric ischemia, rhabdomyolysis, acute renal failure, and hepatotoxicity were diagnosed as delayed toxin-mediated systemic reactions resulting from massive wasp envenomation. Contrast-enhanced computed tomography findings, which included no thrombi or emboli but did reveal the abrupt tapering of mesenteric arteries, strongly suggested that the ischemia was due to nonocclusive mesenteric ischemia. Immediately after diagnosis, an emergency laparotomy was performed. Nonocclusive mesenteric ischemia was finally diagnosed via a histologic examination of the resected small bowel. We present the first case report of nonocclusive mesenteric ischemia consequent to wasp stings.

Specific detection of intramitochondrial superoxide produced by either cell activation or apoptosis by employing a newly developed cell-permeative lucigenin derivative, 10,10'-dimethyl-9,9'-biacridinium bis(monomethyl terephthalate).

Here we developed a new cell-permeative lucigenin derivative, 10,10'-dimethyl-9,9'-biacridinium bis(monomethyl terephthalate) (MMT), to detect intracellular superoxide production. Both MMT and lucigenin were specific to superoxide among reactive oxygen species tested. Although lucigenin barely penetrated into cells, MMT accumulated in mitochondria in a variety of cells such as neutrophils. By employing MMT, we found that, upon activation of neutrophils with phorbol myristate acetate, superoxide was generated extracellularly as well as intramitochondrially and that such intramitochondrial superoxide production was dependent on oxidative phosphorylation. We also found that, during apoptosis, superoxide was gradually produced in mitochondria in association with phosphatidylserine exposure and that the kinetics of superoxide production was very heterogeneous at the single-cell level. Thus this study demonstrates that MMT could serve as a specific probe for intramitochondrial superoxide in either activated or apoptotic cells.