Naoko Mato

Characterization of ST2 transgenic mice with resistance to IL-33

IL‐33, a member of the IL‐1 family, activates MAPK and NF‐κB through its receptor ST2L and IL‐1RAcP. ST2, a member of the IL‐1R superfamily, is a secreted form of ST2 gene products, which has been shown to act as a decoy receptor for IL‐33 and to inhibit the IL‐33/ST2L/IL‐1RAcP signaling pathway. In this work, we generated ST2 transgenic mice. In control mice, intraperitoneal administration of IL‐33 caused an increased number of eosinophils in blood and in peritoneal cavity, an increased number of peritoneal MΦ, splenomegaly, accumulation of periodic acid‐Schiff‐positive material in the lung, and high concentrations of serum IL‐5 and IL‐13. However, these alterations were hardly detectable in ST2 Tg mice. In peritoneal MΦ from IL‐33‐stimulated mice, mRNA expression of M2 MΦ marker genes were increased compared with thioglycollate‐elicited peritoneal MΦ. The IL‐33‐stimulation also increased the secretion of IL‐6 from MΦ. However, when the IL‐33 was preincubated with ST2 prior to its addition to the MΦ cultures, the secretion of IL‐6 was attenuated. These data suggest that, though IL‐33 induced the Th2‐type immune responses and infiltration of M2 type MΦ into the peritoneal cavity, ST2 can downregulate these reactions both in vivo and in vitro.

Physical activity in patients with idiopathic pulmonary fibrosis

Physical activity is an important parameter in patients with chronic obstructive pulmonary disease, but has not been studied in detail in patients with interstitial lung disease. This study aimed to evaluate physical activity in patients with idiopathic pulmonary fibrosis (IPF).

Clinical Significance of Interleukin 33 (IL-33) in Patients with Eosinophilic Pneumonia

BACKGROUND Interleukin 33 (IL-33) works as a functional mediator in allergic disease by enhancing the activity of eosinophils and inducing expression of T helper 2 (Th2)-associated cytokines. However, the role of IL-33 in pulmonary eosinophilia has not been elucidated. We investigated the levels of IL-33 in eosinophilic pneumonia (EP) together with associated cytokines, and discussed the clinical significance of IL-33 in EP. METHODS Sera and bronchoalveolar lavage fluid (BALF) were obtained from 16 patients with EP, including acute eosinophilic pneumonia (AEP) and chronic eosinophilic pneumonia (CEP). Twelve patients with acute respiratory distress syndrome (ARDS) were also included for comparison. The concentration of IL-33 and Th2 cytokines (IL-4, IL-5, IL-13) were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS The concentration of serum IL-33 was significantly higher in patients with AEP than in CEP. In CEP, only patients with atopic factors showed mild increase of serum IL-33. The concentration of BALF IL-33 was also significantly elevated in AEP, however, it remained quite low in CEP. Among Th2 cytokines, IL-5 was significantly increased in both serum and BALF in AEP, and the level of IL-5 was positively correlated with that of IL-33. ARDS showed no increase of serum and BALF IL-33. CONCLUSIONS The remarkable increase of BALF IL-33 in AEP indicated the local production of IL-33 in lungs. IL-33 is considered to be a local key molecule for triggering pulmonary eosinophilia, together with IL-5. BALF IL-33 appears to be a useful marker for discriminating AEP from CEP and ARDS.

NLRP3 Protein Deficiency Exacerbates Hyperoxia-induced Lethality through Stat3 Protein Signaling Independent of Interleukin-1β

Background: The role of NLRP3 inflammasomes in hyperoxic acute lung injury (HALI) remains unclear. Results: NLRP3 deficiency exacerbated lethality and diminished Stat3 activation caused by inflammatory cells in a murine HALI model. Conclusion: NLRP3 regulates Stat3 activation by affecting inflammatory cell infiltration independent of IL-1β. Significance: These findings demonstrate the novel role of NLRP3 in Stat3-mediated protective effects against HALI. Supplemental oxygen inhalation is frequently used to treat severe respiratory failure; however, prolonged exposure to hyperoxia causes hyperoxic acute lung injury (HALI), which induces acute respiratory distress syndrome and leads to high mortality rates. Recent investigations suggest the possible role of NLRP3 inflammasomes, which regulate IL-1β production and lead to inflammatory responses, in the pathophysiology of HALI; however, their role is not fully understood. In this study, we investigated the role of NLRP3 inflammasomes in mice with HALI. Under hyperoxic conditions, NLRP3−/− mice died at a higher rate compared with wild-type and IL-1β−/− mice, and there was no difference in IL-1β production in their lungs. Under hyperoxic conditions, the lungs of NLRP3−/− mice exhibited reduced inflammatory responses, such as inflammatory cell infiltration and cytokine expression, as well as increased and decreased expression of MMP-9 and Bcl-2, respectively. NLRP3−/− mice exhibited diminished expression and activation of Stat3, which regulates MMP-9 and Bcl-2, in addition to increased numbers of apoptotic alveolar epithelial cells. In vitro experiments revealed that alveolar macrophages and neutrophils promoted Stat3 activation in alveolar epithelial cells. Furthermore, NLRP3 deficiency impaired the migration of neutrophils and chemokine expression by macrophages. These findings demonstrate that NLRP3 regulates Stat3 signaling in alveolar epithelial cells by affecting macrophage and neutrophil function independent of IL-1β production and contributes to the pathophysiology of HALI.

Interleukin-1 receptor-related protein ST2 suppresses the initial stage of bleomycin-induced lung injury.

Acute lung injury has a range of causes, and occasionally leads to lethal respiratory failure. Despite advances in treatment, acute lung injury continues to have a high mortality rate, and thus a new therapeutic approach is needed. ST2 is an interleukin (IL)-1 receptor-related protein, and its expression is induced by various inflammatory responses. Recently, ST2 has been speculated to exert anti-inflammatory effects; therefore, we investigated the role of the ST2 in the murine model of acute lung injury. To elucidate the function of ST2 in vivo, mice that transiently overexpressed ST2 protein were prepared using the hydrodynamic gene transfer method, and lung injury was induced by intratracheal administration of bleomycin. In bleomycin-treated ST2-overexpressing mice, the increase of neutrophils in the bronchoalveolar lavage fluid (BALF) was markedly suppressed. Additionally, the levels of tumour necrosis factor-α and IL-6, as well as the concentration of albumin, in BALF were reduced compared with those of controls. Furthermore, the pulmonary architecture in ST2-overexpressing mice remained almost normal, and the survival rate was significantly improved. From these results, we concluded that ST2 has the potential to suppress the initial stage of acute lung injury, and therefore it may be a useful reagent for the treatment of acute lung injury.

Temsirolimus induces surfactant lipid accumulation and lung inflammation in mice

Interstitial lung disease (ILD) is a well-known adverse effect of mammalian target of rapamycin (mTOR) inhibitors. However, it remains unknown how lung toxicities are induced by mTOR inhibitors. Here, we constructed a mouse model of mTOR inhibitor-induced ILD using temsirolimus and examined the pathogenesis of the disease. Male ICR mice were treated with an intraperitoneal injection of different doses of temsirolimus (3 or 30 mg·kg(-1)·wk(-1)) or vehicle. Temsirolimus treatment increased capillary-alveolar permeability and induced neutrophil infiltration and fibrinous exudate into the alveolar space, indicating alveolar epithelial and/or endothelial injury. It also induced macrophage depletion and the accumulation of excessive surfactant phospholipids and cholesterols. Alveolar macrophage depletion is thought to cause surfactant lipid accumulation. To further examine whether temsirolimus has cytotoxic and/or cytostatic effects on alveolar macrophages and alveolar epithelial cells, we performed in vitro experiments. Temsirolimus inhibited cell proliferation and viability in both alveolar macrophage and alveolar epithelial cells. Temsirolimus treatment caused some signs of pulmonary inflammation, including upregulated expression of several proinflammatory cytokines in both bronchoalveolar lavage cells and lung homogenates, and an increase in lymphocytes in the bronchoalveolar lavage fluid. These findings indicate that temsirolimus has the potential to induce alveolar epithelial injury and to deplete alveolar macrophages followed by surfactant lipid accumulation, resulting in pulmonary inflammation. This is the first study to focus on the pathogenesis of mTOR inhibitor-induced ILD using an animal model.

Effect of hochuekkito on alveolar macrophage inflammatory responses in hyperglycemic mice.

Diabetes mellitus reduces immunological activity and increases susceptibility to various infections. Hochuekkito (TJ-41) has been reported to improve the weakened physical condition of various chronic diseases. BALB/c mice were divided into three groups; groups A and B were fed a standard diet, and group C, a TJ-41 diet. Two weeks after starting these diets, hyperglycemia was induced in groups B and C by injection with streptozotocin. Two weeks later, bronchoalveolar lavage was performed. Toll-like receptor (TLR) ligands (TLR2: peptidoglycan, PGN; TLR4: lipopolysaccharide, LPS; TLR5: flagellin, FLG) were used to stimulate alveolar macrophages (AMs), and TNF-α production was measured. Under hyperglycemic conditions and PGN or FLG stimulation, TNF-α production from AMs was significantly reduced in group B compared with group A. However, treatment with TJ-41 (group C) significantly improved the impaired production of TNF-α. These results suggest that, under hyperglycemic conditions, TJ-41 can improve the inflammatory responses of AMs with stimulation of TLR ligands.

Nutritional control of IL-23/Th17-mediated autoimmune disease through HO-1/STAT3 activation

The nutritional curcumin (CUR) is beneficial in cell-mediated autoimmune diseases. The molecular mechanisms underlying this food-mediated silencing of inflammatory immune responses are poorly understood. By investigating antigen-specific immune responses we found that dietary CUR impairs the differentiation of Th1/Th17 cells in vivo during encephalomyelitis and instead promoted Th2 cells. In contrast, feeding CUR had no inhibitory effect on ovalbumin-induced airway inflammation. Mechanistically, we found that CUR induces an anti-inflammatory phenotype in dendritic cells (DC) with enhanced STAT3 phosphorylation and suppressed expression of Il12b and Il23a. On the molecular level CUR readily induced NRF2-sensitive heme oxygenase 1 (HO-1) mRNA and protein in LPS-activated DC. HO-1 enhanced STAT3 phosphorylation, which enriched to Il12b and Il23a loci and negatively regulated their transcription. These findings demonstrate the underlying mechanism through which a nutritional can interfere with the immune response. CUR silences IL-23/Th17-mediated pathology by enhancing HO-1/STAT3 interaction in DC.

Serum Torque Teno Virus DNA Titer in Idiopathic Pulmonary Fibrosis Patients with Acute Respiratory Worsening

OBJECTIVE Acute respiratory worsening is defined as the unexpected rapid deterioration of idiopathic pulmonary fibrosis (IPF), and idiopathic acute respiratory worsening is known as an acute exacerbation of IPF. Torque teno virus (TTV) is a circular single-stranded DNA virus whose pathological significance remains unclear. The aim of the present study was to investigate the prevalence and titer of TTV DNA in IPF patients with acute respiratory worsening. METHODS The serum TTV DNA titer was measured using real-time PCR in nine IPF patients (two treated with steroids and immunosuppressants; seven treated without steroids or immunosuppressants) who developed acute worsening, including five patients with acute exacerbation. The serum TTV DNA titer was also measured in eight stable IPF cases and four IPF cases of lung cancer. In addition, in order to examine time course changes in the TTV DNA titer, the titer was measured more than once, with an interval of four weeks or longer, in eight patients. RESULTS Among the nine IPF patients with acute worsening, the TTV DNA titer was above 1×10(6) copies/mL in two subjects without acute exacerbation who had been continuously treated with steroids and immunosuppressants. Meanwhile, the mean TTV DNA titer was 2.4±2.6 (×10(4) copies/mL) in the five patients with acute exacerbation and 3.1±3.4 (×10(4) copies/mL) in the eight patients with stable IPF. Moreover, the TTV DNA titers were increased in all three IPF patients who started treatment with steroids and immunosuppressants. CONCLUSION Our results suggest that it is unlikely that TTV is directly involved in the onset of acute exacerbation of IPF and that the serum TTV DNA titer potentially reflects the immunosuppressive state of the host due to treatment.

Age-related differences in chest radiographic staging of sarcoidosis in Japan

To the Editor: Sarcoidosis is generally thought to occur more frequently in adults 50 years of age [2, 3]. When comparing the results of national epidemiological surveys conducted in Japan between 1960 and 2004, the incidence rate in females >50 years of age can be seen to have gradually increased while that for bilateral hilar lymphadenopathy (BHL) has decreased [3]. However, whether there is any association between these trends in Japan remains to be elucidated. An earlier study conducted in Europe suggested that older patients are less likely to present with stage 1 sarcoidosis at diagnosis [2]. Against this background, in this study, we aimed to identify the age-related differences in chest radiographic staging of sarcoidosis in Japan. We reviewed 588 consecutive Japanese patients newly diagnosed with sarcoidosis (431 biopsy proven and 157 clinically proven) who were admitted to or underwent bronchoscopy between April 1974 and July 2012 at Jichi Medical University Hospital (Tochigi, Japan). The diagnosis was made based on the diagnostic criteria and guidelines for sarcoidosis developed by the Japanese Society of Sarcoidosis and Other Granulomatous Disorders in 2007 [4]. We compared chest radiographic staging between subgroups differentiated by sex and age at diagnosis (younger diagnosis group <45 years of age, older …