Amelioration of Diabetes by Protein S

Protein S is an anticoagulant factor that also regulates inflammation and cell apoptosis. The effect of protein S on diabetes and its complications is unknown. This study compared the development of diabetes between wild-type and transgenic mice overexpressing human protein S and the development of diabetic glomerulosclerosis between mice treated with and without human protein S and between wild-type and protein S transgenic mice. Mice overexpressing protein S showed significant improvements in blood glucose level, glucose tolerance, insulin sensitivity, and insulin secretion compared with wild-type counterparts. Exogenous protein S improved insulin sensitivity in adipocytes, skeletal muscle, and liver cell lines in db/db mice compared with controls. Significant inhibition of apoptosis with increased expression of BIRC3 and Bcl-2 and enhanced activation of Akt/PKB was induced by protein S in islet β-cells compared with controls. Diabetic wild-type mice treated with protein S and diabetic protein S transgenic mice developed significantly less severe diabetic glomerulosclerosis than controls. Patients with type 2 diabetes had significantly lower circulating free protein S than healthy control subjects. This study shows that protein S attenuates diabetes by inhibiting apoptosis of β-cells and the development of diabetic nephropathy.

Protein S exacerbates alcoholic hepatitis by stimulating liver natural killer T cells

BACKGROUND

Alcohol consumption is a major cause of liver injury but the mechanisms are not completely understood. Protein S (PS) is an anticoagulant glycoprotein with multiple functions. The role of PS in liver injury is unknown.

OBJECTIVES

This study investigated the role of PS in acute alcoholic hepatitis.

METHODS

A mouse overexpressing human PS (hPS-TG) was generated in which acute hepatitis was induced by intraperitoneal injection of ethanol.

RESULTS

The levels of serum liver enzymes and liver tissue inflammatory cytokines and the degree of hepatic steatosis were significantly increased in hPS-TG mice treated with ethanol compared with ethanol-treated wild type (WT) mice. Cell expansion, activation and inhibition of apoptosis were significantly augmented in natural killer T (NKT) cells from hPS-TG mice compared with WT mice. Liver mononuclear cells from hPS-TG mice express higher levels of inflammatory cytokines than those from WT mice after stimulation with a specific stimulant of NKT cells in vitro. In a co-culture system of hepatocytes and NKT cells, the effects of PS on ethanol-mediated cell injury were suppressed by a CD1d neutralizing antibody. Alcoholic liver injury was significantly improved in mice pre-treated with PS siRNA and anti-protein S antibody compared with control mice. Patients with alcoholic hepatitis showed significantly increased plasma PS levels and enhanced liver expression of PS and CD1d compared with controls.

CONCLUSIONS

The results of this study suggest that PS exacerbates acute alcoholic hepatitis by inhibiting apoptosis of activated NKT cells.

Thrombin-activatable fibrinolysis inhibitor protects against acute lung injury by inhibiting the complement system

Acute lung injury (ALI) is a devastating disease with an overall mortality rate of 30 to 40%. The coagulation/fibrinolysis system is implicated in the pathogenesis of ALI. Thrombin-activatable fibronolysis inhibitor (TAFI) is an important component of the fibrinolysis system. Recent studies have shown that the active form of TAFI can also regulate inflammatory responses by its ability to inhibit complement C3a, C5a, and osteopontin. We hypothesized that TAFI might have a protective role in ALI. To demonstrate this hypothesis, the development of ALI was compared between wild-type (WT) and TAFI-deficient mice. ALI was induced by intratracheal instillation of LPS. Control mice were treated with saline. Animals were killed 24 hours after LPS. The number of inflammatory cells and the concentration of total protein and inflammatory cytokines were significantly increased in bronchoalveolar lavage fluid from LPS-treated, TAFI-deficient mice compared with their WT counterparts. Significantly higher concentrations of C5a were found in bronchoalveolar lavage fluid and plasma in LPS-treated TAFI knockout mice compared with WT mice. Pretreatment with inhaled C5a receptor antagonist blocked the detrimental effects of TAFI deficiency to levels found in WT mice. Our results show that TAFI protects against ALI, at least in part, by inhibiting the complement system.

Efficacy of a novel class of RNA interference therapeutic agents

RNA interference (RNAi) is being widely used in functional gene research and is an important tool for drug discovery. However, canonical double-stranded short interfering RNAs are unstable and induce undesirable adverse effects, and thus there is no currently RNAi-based therapy in the clinic. We have developed a novel class of RNAi agents, and evaluated their effectiveness in vitro and in mouse models of acute lung injury (ALI) and pulmonary fibrosis. The novel class of RNAi agents (nkRNA®, PnkRNA™) were synthesized on solid phase as single-stranded RNAs that, following synthesis, self-anneal into a unique helical structure containing a central stem and two loops. They are resistant to degradation and suppress their target genes. nkRNA and PnkRNA directed against TGF-β1mRNA ameliorate outcomes and induce no off-target effects in three animal models of lung disease. The results of this study support the pathological relevance of TGF-β1 in lung diseases, and suggest the potential usefulness of these novel RNAi agents for therapeutic application.

TNF-α is associated with loss of lean body mass only in already cachectic COPD patients

Background

Systemic inflammation may contribute to cachexia in patients with chronic obstructive pulmonary disease (COPD). In this longitudinal study we assessed the association between circulating C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 levels and subsequent loss of fat free mass and fat mass in more than 400 COPD patients over three years.

Methods

The patients, aged 40–76, GOLD stage II-IV, were enrolled in 2006/07, and followed annually. Fat free mass and fat mass indexes (FFMI & FMI) were calculated using bioelectrical impedance, and CRP, TNF-α, IL-1ß, and IL-6 were measured using enzyme immunoassays. Associations with mean change in FFMI and FMI of the four inflammatory plasma markers, sex, age, smoking, FEV₁, inhaled steroids, arterial hypoxemia, and Charlson comorbidity score were analyzed with linear mixed models.

Results

At baseline, only CRP was significantly (but weakly) associated with FFMI (r = 0.18, p < 0.01) and FMI (r = 0.27, p < 0.01). Univariately, higher age, lower FEV₁, and use of beta2-agonists were the only significant predictors of decline in FFMI, whereas smoking, hypoxemia, Charlson score, and use of inhaled steroids predicted increased loss in FMI. Multivariately, high levels of TNF-α (but not CRP, IL-1ß or IL-6) significantly predicted loss of FFMI, however only in patients with established cachexia at entry.

Conclusion

This study does not support the hypothesis that systemic inflammation is the cause of accelerated loss of fat free mass in COPD patients, but suggests a role for TNF-α in already cachectic COPD patients.

Differential role of regulatory T cells in early and late stages of pulmonary fibrosis

Regulatory T cells (Tregs) are a specific subset of T lymphocytes that regulate the function of other subsets of lymphocytes. Contradictory results have been reported regarding the role of Tregs in lung fibrosis. We wished to clarify the role of Tregs in the early and late stages of bleomycin-induced lung fibrosis in mice by depleting them with anti-CD25+ antibody (PC61). Mice treated with PC61 in early stages had significantly decreased number of CD4+CD25+ T cells compared to mice treated with the isotype control. The number of inflammatory cells, the concentrations of collagen, TGFβ1, the content of collagen and hydroxyproline in lung tissue were significantly reduced in PC61-treated mice compared to mice treated with the isotype control group. Pathological examination of the lung also disclosed reduced fibrotic changes and decreased fibrosis score in the PC61 group compared to control group. By contrast, mice treated with PC61 in late stages of the disease showed more infiltration of inflammatory cells and higher fibrotic score and hydroxyproline content in the lungs than mice treated with the isotype control. Our results suggest that Tregs play a detrimental role in early stages but protective role in late stages of pulmonary fibrosis in mice.

Exogenous activated protein C inhibits the progression of diabetic nephropathy

BACKGROUND

Activated protein C (APC) can regulate immune and inflammatory responses and apoptosis. Protein C transgenic mice develop less diabetic nephropathy but whether exogenous administration of APC suppresses established diabetic nephropathy is unknown.

OBJECTIVES

We investigated the therapeutic potential of APC in mice with streptozotocin-induced diabetic nephropathy.

METHODS

Diabetes was induced in unilaterally nephrectomized C57/Bl6 mice using intraperitoneal (i.p.) injection of streptozotocin. Four weeks later, the mice were treated with i.p. exogenous APC every other day for 1 month.

RESULTS

APC-treated mice had a significantly improved blood nitrogen urea-to-creatinine ratio, urine total protein to creatinine ratio and proteinuria, and had significantly less renal fibrosis as measured by the levels of collagen and hydroxyproline. The renal tissue concentration of monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF) and the RNA expression of platelet-derived growth factor (PDGF), transforming growth factor-β1 and connective tissue growth factor (CTGF) were significantly lower in APC-treated mice than in untreated animals. The percentage of apoptotic cells was reduced and the expression of podocin, nephrin and WT-1 in the glomeruli was significantly improved in mice treated with APC compared with untreated mice. The levels of coagulation markers were not affected by APC treatment.

CONCLUSION

Exogenous APC improves renal function and mitigates pathological changes in mice with diabetic nephropathy by suppressing the expression of fibrogenic cytokines, growth factors and apoptosis, suggesting its potential usefulness for the therapy of this disease.

Development and preclinical efficacy of novel transforming growth factor-β1 short interfering RNAs for pulmonary fibrosis

Idiopathic pulmonary fibrosis is a chronic devastating disease of unknown etiology. No therapy is currently available. A growing body of evidence supports the role of transforming growth factor (TGF)-β1 as the major player in the pathogenesis of the disease. However, attempts to control its expression and to improve the outcome of pulmonary fibrosis have been disappointing. We tested the hypothesis that TGF-β1 is the dominant factor in the acute and chronic phases of pulmonary fibrosis and developed short interfering (si)RNAs directed toward molecules implicated in the disease. This study developed novel sequences of siRNAs targeting the TGF-β1 gene and evaluated their therapeutic efficacy in two models of pulmonary fibrosis: a model induced by bleomycin and a novel model of the disease developed spontaneously in mice overexpressing the full length of human TGF-β1 in the lungs. Intrapulmonary delivery of aerosolized siRNAs of TGF-β1 with sequences common to humans and rodents significantly inhibited bleomycin-induced pulmonary fibrosis in the acute and chronic phases of the disease and in a dose-dependent manner. Aerosolized human-specific siRNA also efficiently inhibited pulmonary fibrosis, improved lung function, and prolonged survival in human TGF-β1 transgenic mice. Mice showed no off-target effects after intratracheal administration of siRNA. These results suggest the applicability of these novel siRNAs as tools for treating pulmonary fibrosis in humans.

Atherosclerosis amelioration by moderate alcohol consumption is associated with increased circulating levels of stromal cell-derived factor-1

BACKGROUND

A moderate intake of alcohol is associated with lower cardiovascular mortality, and the role of circulating progenitor cells in the beneficial effect of alcohol on atherosclerosis is unclear. The hypothesis of this study was that alcohol ameliorates atherosclerosis by modulating the circulating levels of stromal cell-derived growth factor (SDF)-1 and vascular progenitor cells.

METHODS AND RESULTS

Atherosclerosis was induced by infusion of angiotensin II in apolipoprotein-E deficient mice, which were treated with high and low doses of ethanol for 28 days by intraperitoneal injection. Mice treated with low-dose ethanol had significantly less dilatation and fewer atheromatous lesions than mice receiving the high-dose ethanol. The number of circulating fibrocytes was significantly lower in mice treated with high-dose ethanol compared with mice with atherosclerosis untreated with ethanol. The plasma CXCL12/SDF-1 level was significantly increased in mice treated with low-dose ethanol compared with mice treated with a high dose, and the plasma concentration of transforming growth factor-β1 was significantly increased in mice treated with high-dose ethanol compared with control mice. Ethanol regulated the secretion of SDF-1 and vascular endothelial growth factor from fibroblasts in a dose-dependent and bimodal fashion.

CONCLUSIONS

The circulating level of CXCL12/SDF-1 may be involved, at least in part, in the differential effects of alcohol consumption on atherosclerosis.

High incidence of tumors in diabetic thrombin activatable fibrinolysis inhibitor and apolipoprotein E double-deficient mice

BACKGROUND

Activation of the complement system has been implicated in tumor growth. The antifibrinolytic protein, activated thrombin-activatable fibrinolysis inhibitor (TAFIa), can modulate the activation of the complement system by inactivating the anaphylatoxins C3a and C5a. The apolipoprotein-E (ApoE) genotype has been associated with carcinogenesis.

OBJECTIVE

The aim of this study was to evaluate whether TAFIa can affect the development of cancer in the ApoE-deficient mouse model.

METHODS

TAFI and ApoE double-knockout mice were generated. A group of mice was treated with the diabetogenic and carcinogenic compound streptozotocin (stz). Mice treated with saline, single knockout mice and wild-type (wt) mice served as controls.

RESULTS

Six months after treatment with stz, mice were sacrificed. Hepatic tumors were found in male double-knockout mice treated with stz but none was found in control animals that were not treated with stz or in single knockout of ApoE or wt animals. There was no significant difference in coagulation system activation between the groups of mice. The plasma concentrations of C5a, factor D and transforming growth factor-β1 were increased in TAFI/ApoE double-deficient mice treated with stz compared with the mice of the same genotype treated with saline.

CONCLUSION

Apo-E deficiency alone was not associated with tumors but the lack of TAFI appears to make the mice permissive for tumor formation in ApoE mice.

Pulmonary hypertension is ameliorated in mice deficient in thrombin-activatable fibrinolysis inhibitor

BACKGROUND

The fibrinolytic system has been implicated in the pathogenesis of pulmonary hypertension (PH). Thrombin-activatable fibrinolysis inhibitor (TAFI) inhibits fibrinolysis and therefore its absence would be expected to increase fibrinolysis and ameliorate PH.

OBJECTIVE

The objective of the present study was to evaluate the effect of TAFI deficiency on pulmonary hypertension in the mouse.

METHODS AND RESULTS

PH was induced in C57/Bl6 wild-type (WT) or TAFI-deficient (KO) mice by weekly subcutaneous treatment with 600 mg kg(-1) monocrotaline (MCT) for 8 weeks. PH was inferred from right heart hypertrophy measured using the ratio of right ventricle-to-left ventricle-plus-septum weight [RV/(LV+S)]. Pulmonary vascular remodeling was analyzed by morphometry. TAFI-deficient MCT-treated and wild-type MCT-treated mice suffered similar weight loss. TAFI-deficient MCT-treated mice had reduced levels of total protein and tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor-beta (TGF-beta) and monocyte chemoattractant protein-1 (MCP-1) in bronchial alveolar lavage compared with wild-type MCT-treated mice. The ratio of RV to (LV+S) weight was significantly higher in WT/MCT than in KO/MCT mice. The pulmonary artery wall area and vascular stenosis were both greater in MCT-treated WT mice compared with MCT-treated TAFI-deficient mice.

CONCLUSIONS

TAFI-deficient MCT-treated mice had less pulmonary hypertension, vascular remodeling and reduced levels of cytokines compared with MCT-treated WT animals, possibly as a result of reduced coagulation activation.

Direct effects of protein S in ameliorating acute lung injury

OBJECTIVE

Protein S may exert an anticoagulant activity by enhancing the anticoagulant activity of activated protein C and/or by directly inhibiting the prothrombinase complex. Protein S itself may also directly regulate inflammatory responses and apoptosis. The role of protein S in acute lung injury (ALI) was unknown. This study evaluated the effect of protein S on ALI in the mouse.

METHODS

Animal ALI was induced in C57/BL6 mice by intratracheal instillation of lipopolysaccharide (LPS). Mice were treated with protein S or saline by intraperitoneal injection 1 h before LPS instillation.

RESULTS

Activated protein or protein S alone and combined activated protein C + protein S therapy decreased inflammatory markers and cytokines in mice with acute lung injury. In LPS-treated mice compared with controls ALI was induced as shown by significantly increased levels of total protein, tumor necrosis factor-alpha, interleukin-6 and monocyte chemoattractant protein-1 in the bronchoalveolar lavage fluid. Mice with ALI treated with protein S had significantly decreased concentrations of tumor necrosis factor-alpha and interleukin-6 in the lung compared with untreated animals. Thrombin-antithrombin III, a marker of the activity of the coagulation cascade, was unchanged. Protein S inhibited the expression of cytokines in vitro and increased activation of the Axl tyrosine kinase pathway in A549 epithelial cells.

CONCLUSION

Protein S protects against LPS-induced ALI, possibly by directly inhibiting the local expression of inflammatory cytokines without affecting coagulation.