Takuya Yokoe

Intermittent hypoxia reverses the diurnal glucose rhythm and causes pancreatic β‐cell replication in mice

Obstructive sleep apnoea (OSA) and type 2 diabetes frequently co‐exist and potentially interact haemodynamically and metabolically. However, the confounding effects of obesity have obscured the examination of any independent or interactive effects of the hypoxic stress of OSA and the hyperglycaemia of type 2 diabetes on haemodynamic and metabolic outcomes. We have developed a chronically catheterized, unhandled, lean murine model to examine the effects of intermittent hypoxic (IH) exposure and exogenous glucose infusion on the diurnal pattern of arterial blood pressure and blood glucose, as well as pancreatic β‐cell growth and function. Four experimental groups of adult male C57BL/J mice were exposed to 80 h of (1) either IH (nadir of inspired oxygen 5–6% at 60 cycles h−1 for 12 h during light period) or intermittent air (IA; control) and (2) continuous infusion of either 50% dextrose or saline (control). IH exposure during saline infusion caused a sustained increase in arterial blood pressure of 10 mmHg (P < 0.0001), reversed the normal diurnal rhythm of blood glucose (P < 0.03), doubled corticosterone levels (P < 0.0001), and increased replication of pancreatic β‐cells from 1.5 ± 0.3 to 4.0 ± 0.8% bromodeoxyuridine (BrdU)‐positive) β‐cells. The combined stimulus of IH exposure and glucose infusion attenuated the hypertension, exacerbated the reversed diurnal glucose rhythm, and produced the highest rates of apoptosis in β‐cells, without any additive effects on β‐cell replication. We conclude that, in contrast to the development of sustained hypertension, IH impaired glucose homeostasis only during periods of hypoxic exposure. IH acted as a stimulus to pancreatic β‐cell replication, but the presence of hyperglycaemia may increase the hypoxic susceptibility of β‐cells. This model will provide a basis for future mechanistic studies as well as assessing the metabolic impact of common comorbities in OSA, including obesity, insulin resistance and type 2 diabetes.

Modulation by proinflammatory cytokines of Fas/Fas ligand-mediated apoptotic cell death of synovial cells in patients with rheumatoid arthritis (RA)

Synovial cell hyperplasia is a characteristic of patients with RA. Excessive proliferation of RA synovial cells is, in part, responsible for the synovial cell hyperplasia. In addition, synovial cell death that would reduce synovial cell number may be defective, leading to the hyperplasia. Thus, the defective control of cell death as well as cell proliferation may be of central importance in the pathogenesis of RA. In this study we analysed effects of proinflammatory cytokines on Fas/Fas ligand (FasL)‐induced synovial cell apoptosis, and evaluated apoptosis‐associated protein expression in the synovial cells in patients with RA. RA synovial cells expressed Fas antigen and lymphocytes infiltrating into RA synovium expressed FasL. Apoptotic synovial cells were detected within the sublining layer of RA synovium. Anti‐Fas MoAb induced apoptosis of RA synovial cells in vitro, and proinflammatory cytokines tumour necrosis factor‐alpha (TNF‐α) and IL‐1β, but not IL‐6 or IL‐8, inhibited the anti‐Fas‐induced apoptosis accompanying up‐regulation of Bcl‐2 protein expression and reduced expression of CPP32 and ICH‐1L. Immunohistochemical study revealed that CPP32 and ICH‐1L were expressed weakly in the RA synovial lining cells compared with osteoarthritis (OA) synovial lining cells. Thus, we found that although RA synovial cells could die via apoptosis through Fas/FasL pathway, apoptosis of synovial cells was inhibited by proinflammatory cytokines present within the synovium. Inhibition of apoptosis by the proinflammatory cytokines may contribute outgrowth of synovial cells that leads to pannus formation and the destruction of joints in patients with RA.

Effect of rush immunotherapy on airway inflammation and airway hyperresponsiveness after bronchoprovocation with allergen in asthma

BACKGROUNDnRush immunotherapy (RIT) has been shown to be effective in allergic asthma.nnnOBJECTIVEnWe investigated the mechanisms of RIT on the basis of cytokine production by T-cell lines and airway inflammation and responsiveness.nnnMETHODSnSubjects were 8 patients with house dust mite-allergic asthma treated with dust mite extract RIT for 6 months and 6 RIT-untreated control patients. IL-5 production by Dermatophagoides farinae -specific T-cell lines, eosinophil percentages, and eosinophil cationic protein (ECP) in induced sputum and airway responsiveness to allergen and histamine were evaluated before and after treatment. Changes in eosinophil percentages and ECP in induced sputum and responsiveness to histamine 24 hours after allergen inhalation were also studied.nnnRESULTSnAfter 6 months of RIT, percentages of total eosinophils (43. 0% +/- 6.90% to 16.8% +/- 2.48%; P <.01), percentages of EG2(+ ) eosinophils (32.6% +/- 6.39% to 19.7% +/- 4.68%; P <.01) and ECP (362.7 +/- 125.3 ng/mL to 26.2 +/- 5.15 ng/mL; P <.05) decreased in induced sputum, and IL-5 production by T-cell lines decreased (617 +/- 93.2 pg/mL to 200.0 +/- 34.1 pg/mL; P <.01). RIT decreased both early- and late-phase bronchoconstriction (early phase: 33.2% +/- 3. 46% to 25.4% +/- 1.42%; P <.03; late phase: 16.2% +/- 3.52% to 6.2% +/- 1.96%; P <.03) and suppressed increases in the percentages of total (61.8% +/- 4.89% to 42.0% +/- 4.67%; P <.01) and EG2-positive eosinophils (55.54% +/- 7.21% to 36.5% +/- 6.43%; P <.01) and ECP (685.6 +/- 217.0 ng/mL to 85.4 +/- 23.4 ng/mL; P <.05) in induced sputum after allergen inhalation. RIT also decreased airway responsiveness to dust mite (1:303.7 +/- 123.7 wt/vol to 1:65.0 +/- 13.2 wt/vol; P <.03) and to histamine before (397.1 +/- 206.9 microgra/mL to 1391.3 +/- 283.3 microgram/mL; P <.03) and after allergen inhalation (139.2 +/- 36.5 microgram/mL to 629.1 +/- 196.3 microgram/mL; P <.03).nnnCONCLUSIONnRIT decreases airway inflammation and airway hyperresponsiveness before and after bronchial provocation with allergen, possibly by inhibiting both allergen-specific T-cell- and mast cell-dependent pathways. RIT is an effective antiinflammatory treatment in allergic asthma.

Activated protein C attenuates leukocyte elastase-induced lung injury in mice.

Leukocyte elastase (LE), a neutrophil serine protease, is known to cause alveolar wall destruction and alveolar hemorrhage in the lung, but recent evidence suggests that it may also produce a significant inflammatory response. The purpose of the current study was to (1) examine the relationship between LE-induced lung injury and specific markers of inflammation and cytokine/chemokine, and to (2) determine the potential of activated protein C (APC), a potent immunomodulator, to block the inflammatory response to LE. We treated the C57BL/6 mice with LE (10 U/kg, i.t.) and assessed the lung inflammation over 72 h. Total cells, total protein, and neutrophils were increased and peaked at 16 h in bronchial alveolar lavage fluid. Macrophages were also increased and peaked at 24 h. Administration of LE up-regulated the synthesis of proinflammatory cytokines, IL-1&bgr; and IL-6, chemokines, keratinocyte-derived chemokine, and macrophage inflammatory protein 2 in bronchial alveolar lavage fluid, and their peaks were at 6 h. Furthermore, the mice were treated with APC at 0.2, 2.0, and 10 mg/kg (i.v.) after instillation of LE. Therapeutic treatment of APC at 2.0 and 10 mg/kg significantly attenuated the increases in all these parameters. Lung histology revealed that, in addition to inflammation, alveolar hemorrhage and alveolar wall destruction induced by LE were also attenuated by APC. Finally, the expression of tissue plasminogen activator and plasminogen activator inhibitor in whole lung of mice exposed to LE, detected by means of reverse-transcriptase-polymerase chain reaction, were not influenced by the treatment with APC. These data demonstrate that intratracheal administration of LE to mice causes a transient inflammatory response, and APC can play a protective role against LE-induced lung injury.