Extracellular administration of BCL2 protein reduces apoptosis and improves survival in a murine model of sepsis

Background

Severe sepsis and septic shock are major causes of morbidity and mortality worldwide. In experimental sepsis there is prominent apoptosis of various cell types, and genetic manipulation of death and survival pathways has been shown to modulate organ injury and survival.

Methodology/Principal Findings

We investigated the effect of extracellular administration of two anti-apoptotic members of the BCL2 (B-cell lymphoma 2) family of intracellular regulators of cell death in a murine model of sepsis induced by cecal ligation and puncture (CLP). We show that intraperitoneal injection of picomole range doses of recombinant human (rh) BCL2 or rhBCL2A1 protein markedly improved survival as assessed by surrogate markers of death. Treatment with rhBCL2 or rhBCL2A1 protein significantly reduced the number of apoptotic cells in the intestine and heart following CLP, and this was accompanied by increased expression of endogenous mouse BCL2 protein. Further, mice treated with rhBCL2A1 protein showed an increase in the total number of neutrophils in the peritoneum following CLP with reduced neutrophil apoptosis. Finally, although neither BCL2 nor BCL2A1 are a direct TLR2 ligand, TLR2-null mice were not protected by rhBCL2A1 protein, indicating that TLR2 signaling was required for the protective activity of extracellularly adminsitered BCL2A1 protein in vivo.

Conclusions/Significance

Treatment with rhBCL2A1 or rhBCL2 protein protects mice from sepsis by reducing apoptosis in multiple target tissues, demonstrating an unexpected, potent activity of extracellularly administered BCL2 BH4-domain proteins.     

Specific inhibition of nitric oxide synthases at different time points in a murine model of pulmonary sepsis

Excessive production of nitric oxide (NO) by NO synthase (NOS) and a subsequent oxidative stress reaction are thought to be critically involved in the pathophysiology of sepsis. Previous studies suggested that NO production by neuronal NOS (nNOS) and inducible NOS (iNOS) is implemented in the disease process at different time points after the injury. Here we tested the roles of selective pharmacological inhibition of nNOS and iNOS at different time points in a murine model of pulmonary sepsis. The injury was induced by intranasal administration of live Pseudomonas aeruginosa (3.2 × 10⁷ colony-forming units) in C57BL/6 wild-type mice. The animals received no treatment (control) or treatment with a specific nNOS inhibitor (4 or 8 h), iNOS inhibitor (4 or 8 h), or non-specific NOS inhibitor (4 or 8 h). In controls, the injury was associated with excessive releases of pro-inflammatory cytokines in the plasma, enhanced tissue lipid peroxidation, and decreased survival. Non-specific NOS inhibition at either time point did not influence survival and was not further investigated. While nNOS inhibition at 4 h was associated with a trend toward improved survival and significantly reduced contents of lung nitrite/nitrate (NO_x) and liver malondialdehyde, the blockade of nNOS at 8 h had no effect on these parameters. In contrast, early iNOS inhibition was associated with a trend toward decreased survival and no effects on lung NO_x and liver malondialdehyde contents, whereas later iNOS blockade was associated with decreased malondialdehyde content in liver homogenates. In conclusion, pulmonary sepsis in mice may be beneficially influenced by specific pharmacological nNOS inhibition at an earlier time point and iNOS inhibition at a later time points post-injury. Future investigations should identify the time changes of the expression and activation of NOS isoforms.     

Combined treatment of a murine breast cancer model with type 5 adenovirus vectors expressing murine angiostatin and IL-12: a role for combined anti-angiogenesis and immunotherapy

In this study, we used intratumor delivery of adenoviral vectors to induce a selective anti-tumor response by combining the potent angiogenesis inhibitor murine angiostatin (adenovirus (Ad)-angiostatin) with the powerful immune simulator and angiostatic cytokine murine IL-12 (Ad-IL-12). In a murine model of breast carcinoma, intratumor injection of Ad-angiostatin delayed mean tumor growth, as compared with control virus with an initial regression of tumor growth, in 65% of treated animals. However, all treated animals eventually succumbed to the tumors. Mice injected with Ad-IL-12 alone responded with an initial regression in 20% of treated animals, with only 13% developing a total regression. Coinjection of the vectors resulted in 96% of the treated animals developing an initial regression, with 54% undergoing a total regression of the tumor. These mice were resistant to tumor rechallenge and developed a strong CTL response. Frozen tumor sections were stained for microvessel density using an Ab against murine CD31, an endothelial cell marker. Automated image analysis revealed the mean microvessel density following the administration of Ad-angiostatin and Ad-IL-12 alone or in combination was significantly reduced compared with the control-treated tumor. In summary, we have shown that a short-term course of antiangiogenic therapy combined with immunotherapy can effectively shrink a solid tumor and vaccinate the animal against rechallenge. The rationale for this therapy is to limit the tumor size by attacking the vasculature with angiostatin, thereby allowing IL-12 to mount a T cell-specific response against the tumor AG:     

Mesenchymal stem cells preconditioned by staphylococcal enterotoxin B enhance survival and bacterial clearance in murine sepsis model

Sepsis, a health-threatening progressive infectious disease, is the major cause of morbidity and mortality worldwide. Cell therapy using mesenchymal stromal cells (MSCs) is an innovative strategy with excessive therapeutic potential in the treatment of sepsis. Staphylococcal enterotoxin B (SEB) preconditioning aims to prolong the interval of survival of transplanted MSCs which induces the production of cytoprotective agents, anti-apoptotic and anti-inflammatory factors. The MSCs were preconditioned with an optimum dose of SEB (470 μmol/L). The expression levels of apoptosis genes and antibacterial activity of MSC and SEB-MSC and their conditioned medium (CM), as well as cell survival, were studied in vitro in an oxidative stress and serum deprivation condition. Following treatment of the septic mice with MSCs and SEB-MSCs, pro/anti-inflammatory cytokines, hematological factors, bacterial clearance and animal survival were assessed. The apoptotic and pro-inflammatory cytokine's genes expression was down-regulated while antibacterial peptides and anti-inflammatory cytokines were up-regulated in SEB-MSC–treated mice. The animal survival rates were improved; bacterial clearance was enhanced in the peritoneal fluids, blood and organs; aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were reduced in blood, compared with saline and MSCs alone. This research concludes that transplantation of SEB-MSCs presents improved therapeutic effects on a live bacterial model of sepsis.     

Effects of Cl2MDP-encapsulating liposomes in a murine model of Pseudomonas aeruginosa-induced sepsis

Pseudomonas aeruginosa is a pathogen that frequently causes acute lung injury, bacteremia and sepsis in critically ill patients. As tissue macrophages are a major producer of inflammatory mediators that contribute to septic physiology, and are essential for eliminating bacteria from the circulation, we investigated the role of tissue macrophages in the generation of both inflammatory and anti-inflammatory cytokines in septic shock by using our mouse model of P. aeruginosa pneumonia. To see the effects of tissue macrophage depletion, we intravenously injected dichloromethylene-diphosphonate (Cl2MDP)-encapsulating liposomes in mice. Two days after the liposome injection, we instilled cytotoxic P. aeruginosa (PA103) into the lung that disseminates and causes septic shock. After the infection, we collected blood and bronchoalveolar lavage fluids. The samples were then analyzed for TNF-alpha, MIP-2, and IL-10 concentration. We compared these results to control mice that received either liposomes without Cl2MDP or phosphate buffered saline alone. Plasma TNF-alpha, MIP-2, and IL-10 levels were significantly decreased in the tissue macrophage-depleted mice compared to the control groups of mice. Although depletion of tissue macrophages by Cl2MDP-liposome administration did not affect the severity of bacteremia or the survival of infected mice, these results imply that tissue macrophages have a major role in the production of both proinflammatory and anti-inflammatory cytokines in the circulation and in the causing septic physiology associated with P. aeruginosa pneumonia.     

A murine model of sepsis following smoke inhalation injury

Acute lung injury (ALI) by smoke inhalation with subsequent pneumonia and sepsis represents a major cause of morbidity and mortality in burn patients. The aim of the present study was to develop a murine model of ALI and sepsis to enhance the knowledge of mechanistic aspects and pathophysiological changes in patients with these injuries. In deeply anesthetized female C57BL/6 mice, injury was induced by four sets of cotton smoke using an inhalation chamber. Afterward, live Pseudomonas aeruginosa (3.2 × 10⁷ colony-forming units) was administered intranasally. The indicated dose of bacteria was determined based on the results of a dose-response study (n = 47). The following study groups were monitored for survival over 96 h: (1) sham injury group, (2) only smoke inhalation group, (3) only bacteria group, and (4) smoke inhalation plus bacteria group. Each group included 10 mice. The survival rates were 100%, 90%, 30%, and 10%, respectively. The double hit injury was associated with excessive releases of pro-inflammatory cytokines in the plasma, and enhanced neutrophil accumulation, increased lipid peroxidation, and excessive formation of reactive nitrogen species in the lung. In mice receiving only smoke inhalation injury, no systemic cytokine release and increased lung tissue lipid peroxidation were observed. However, smoke alone significantly increased neutrophil accumulation and formation of reactive nitrogen species in lung tissue. In conclusion, bacterial pneumonia is predominantly responsible for mortality and morbidity in this novel murine model of smoke inhalation and pulmonary sepsis. Reactive oxygen and nitrogen species mediate the severity of lung injury.     

Inosine reduces inflammation and improves survival in a murine model of colitis

Inosine, a naturally occurring purine formed from the breakdown of adenosine, has recently been shown to exert powerful anti-inflammatory effects both in vivo and in vitro. This study evaluated inosine as a potential therapy for colitis. Colitis was induced in mice by the administration of dextran sulfate sodium (DSS). Oral treatment with inosine was begun either before the onset of colitis or as a posttreatment once colitis was established. Evaluation of colon damage and inflammation was determined grossly (body wt, rectal bleeding), histologically, and biochemically (colon levels of MPO, MDA, and cytokines). DSS-induced colitis significantly increased inflammatory cell infiltration into the colon. DSS-induced colitis also increased colon levels of lipid peroxidation, cytokines, and chemokines. Inosine protected the colon from DSS-induced inflammatory cell infiltration and lipid peroxidation. Inosine also partially reduced these parameters in an experimental model of established colitis. Thus inosine treatment may be a potential therapy in colitis.     

RNAIII-inhibiting peptide improves efficacy of clinically used antibiotics in a murine model of staphylococcal sepsis

RNAIII-inhibiting peptide (RIP, YSPWTNF-NH2) is a quorum-sensing peptide inhibitor that prevents Staphylococcus aureus toxin production and biofilm formation. A mouse sepsis model was used to test the efficacy of RIP alone or in combination with conventional antibiotics in suppressing S. aureus-induced sepsis. Mice were injected intravenously with 3.0x10(6)CFU of S. aureus ATCC 25923 or with 3.0x10(6)CFU of S. aureus strain Smith diffuse. All animals were randomized to receive intravenously isotonic sodium chloride solution as a control, or 20 mg/kg RIP alone or combined with 20 mg/kg cefazolin, 10 mg/kg imipenem, or 10 mg/kg vancomycin immediately or 6 h after bacterial challenge. Main outcome measures were bacteremia and lethality. All compounds reduced lethality when compared to controls. Although, in general combined-treated groups had significant lower bacterial counts when associated to singly-treated groups only the combination between RIP and vancomycin with respect to cefazolin gave a statistically significant decrease in the lethality rate. Lowest lethality rates (10%) and bacteremia (<10(2)CFU/ml) were obtained when RIP was administered in combination with vancomycin. Because RIP can be synergistic with current antibiotic therapies and help to reduce S. aureus exotoxins production, it can be considered a promising agent to associate with antibiotics for further clinical research into treatment of sepsis.     

Methods for construction of adenovirus vectors

Adenoviruses are attracting increasing attention as general purpose mammalian cell expression vectors, as recombinant vaccines, and potentially as vectors for gene therapy. Not only is the adenovirus genome relatively easy to manipulate by recombinant DNA techniques, but adenovirus vectors are relatively stable, grow to high titers, and can transduce a variety of cell types in cell culture and in vivo. Vectors can be designed that are either replication competent or replication defective and, in the latter case, are highly efficient at delivering and expressing genes in mammalian cells without resulting in cell killing. Methods are described for growing, titrating, and purifying adenoviruses, for extracting viral DNA from purified virions and from infected cells, for rescuing inserts of foreign DNA into the viral genome, and for assessing expression of inserted genes in adenovirus vectors.     

Alternate adenovirus type-pairs for a possible circumvention of host immune response to recombinant adenovirus vectors

With the help of monoclonal antibodies the existence of at least 18 different earlier not known intertype (IT) specific epitopes were demonstrated in different numbers and combinations on the hexons of different adenovirus serotypes. The IT specific epitopes play an important role in the experimental gene therapy and in the recombinant adenovirus vaccination because of the harmful immune response of the recipient organisms directed against the many different epitopes of the adenovirus vector. For the elimination of harmful effect the authors suggest the use of multiple vectors, each prepared from different adenovirus serotypes showing the loosest antigenic relationship to each other. The vectors would be used sequentially when second or multiple administration is needed. For this purpose the authors determined and described 31 such adenovirus type-pairs, which are probably the best alternates for sequential use in experimental gene therapy.     

CD11c+ dendritic cells are required for survival in murine polymicrobial sepsis

CD11c+ dendritic cells (DCs) are APCs that link innate and adaptive immunity. Although DCs are lost from spleen and lymph nodes in sepsis, their role in outcome remains unclear. Transgenic mice (B6.FVB-Tg(.Itgax-DTR/EGFP.57)Lan/J) expressing the diphtheria toxin (DT) receptor on the CD11c promoter (DCKO mice) received 4 ng/kg DT, which resulted in depletion of 88-95% of mature myeloid and lymphoid DCs, with less depletion (75%) of plasmacytoid DCs. Pretreatment of DCKO mice with DT resulted in reduced survival in sepsis compared with saline-pretreated DCKO mice (0 vs 54%; p < 0.05) or DT-treated wild-type littermates (0 vs 54%; p < 0.05). This increased mortality was not associated with either increased bacteremia or plasma cytokine concentrations. Intravenous injection of 10(7) wild-type DCs improved survival in DCKO mice (42 vs 0%; p = 0.05). These data confirm that DCs are essential in the septic response and suggest that strategies to maintain DC numbers or function may improve outcome.     

Modulation of extracellular matrix using adenovirus vectors

Metabolism of the extracellular matrix (ECM) is a complex process that becomes disregulated in disease states characterized by chronic inflammation of joints, as is seen in rheumatoid arthritis or fibrosis of the lung. The participation of certain cytokines in this process is generally accepted (transforming growth factor-beta induces fibrosis), while the roles of other cytokines are less clear. Oncostatin M (OSM) is a member of the interleukin-6/leukaemia inhibitory factor (or gp130) cytokine family, and its participation in inflammation and the regulation of ECM metabolism is supported by a number of activities identified in vitro, including regulation of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinases-1. Local overexpression of transforming growth factor-beta has been shown to be fibrogenic in mouse lung, whereas local OSM overexpression via intra-articular administration has been shown to induce a pannus-like inflammatory response in the synovium of mouse knee joints. Here we examine the effects of OSM in the context of those of transforming growth factor-beta using an established adenovirus vector that expresses mOSM (AdmOSM). We administered the virus intra-nasally into Balb/C mice to achieve high expression of OSM in the lung, and examined the effects at various time points. AdmOSM resulted in a vigorous inflammatory response by day 7 which was characterized by an elevation of neutrophil and mononuclear cell numbers and a marked increase in collagen deposition. These data support the use of such systems to study the ECM in vivo, and indicate a potential role for OSM in inflammatory responses that can modulate steady-state ECM deposition in Balb/C mice.     

Conditionally replicating adenovirus expressing TIMP2 increases survival in a mouse model of disseminated ovarian cancer

Ovarian cancer remains difficult to treat mainly due to presentation of the disease at an advanced stage. Conditionally-replicating adenoviruses (CRAds) are promising anti-cancer agents that selectively kill the tumor cells. The present study evaluated the efficacy of a novel CRAd (Ad5/3-CXCR4-TIMP2) containing the CXCR4 promoter for selective viral replication in cancer cells together with TIMP2 as a therapeutic transgene, targeting the matrix metalloproteases (MMPs) in a murine orthotopic model of disseminated ovarian cancer. An orthotopic model of ovarian cancer was established in athymic nude mice by intraperitonal injection of the human ovarian cancer cell line, SKOV3-Luc, expressing luciferase. Upon confirmation of peritoneal dissemination of the cells by non-invasive imaging, mice were randomly divided into four treatment groups: PBS, Ad-ΔE1-TIMP2, Ad5/3-CXCR4, and Ad5/3-CXCR4-TIMP2. All mice were imaged weekly to monitor tumor growth and were sacrificed upon reaching any of the predefined endpoints, including high tumor burden and significant weight loss along with clinical evidence of pain and distress. Survival analysis was performed using the Log-rank test. The median survival for the PBS cohort was 33 days; for Ad-ΔE1-TIMP2, 39 days; for Ad5/3-CXCR4, 52.5 days; and for Ad5/3-CXCR4-TIMP2, 63 days. The TIMP2-armed CRAd delayed tumor growth and significantly increased survival when compared to the unarmed CRAd. This therapeutic effect was confirmed to be mediated through inhibition of MMP9. Results of the in vivo study support the translational potential of Ad5/3-CXCR4-TIMP2 for treatment of human patients with advanced ovarian cancer.     

Exenatide improves glucose homeostasis and prolongs survival in a murine model of dilated cardiomyopathy

Background

There is growing awareness of secondary insulin resistance and alterations in myocardial glucose utilization in congestive heart failure. Whether therapies that directly target these changes would be beneficial is unclear. We previously demonstrated that acute blockade of the insulin responsive facilitative glucose transporter GLUT4 precipitates acute decompensated heart failure in mice with advanced dilated cardiomyopathy. Our current objective was to determine whether pharmacologic enhancement of insulin sensitivity and myocardial glucose uptake preserves cardiac function and survival in the setting of primary heart failure.

Methodology/Principal Findings

The GLP-1 agonist exenatide was administered twice daily to a murine model of dilated cardiomyopathy (TG9) starting at 56 days of life. TG9 mice develop congestive heart failure and secondary insulin resistance in a highly predictable manner with death by 12 weeks of age. Glucose homeostasis was assessed by measuring glucose tolerance at 8 and 10 weeks and tissue 2-deoxyglucose uptake at 75 days. Exenatide treatment improved glucose tolerance, myocardial GLUT4 expression and 2-deoxyglucose uptake, cardiac contractility, and survival over control vehicle-treated TG9 mice. Phosphorylation of AMP kinase and AKT was also increased in exenatide-treated animals. Total myocardial GLUT1 levels were not different between groups. Exenatide also abrogated the detrimental effect of the GLUT4 antagonist ritonavir on survival in TG9 mice.

Conclusion/Significance

In heart failure secondary insulin resistance is maladaptive and myocardial glucose uptake is suboptimal. An incretin-based therapy, which addresses these changes, appears beneficial.     

Enhancement of NF-kappaB activation in lymphocytes prevents T cell apoptosis and improves survival in murine sepsis

Sepsis induces extensive lymphocyte apoptosis that contributes to immunosuppression and mortality. Activation of the canonical NF-kappaB pathway, however, prevents TNF-alpha-induced lymphocyte apoptosis. In this study the function of canonical NF-kappaB in T cells was studied in the context of murine sepsis. Upon cecal ligation and puncture (CLP), NF-kappaB DNA binding activity in thymocytes declines relative to sham-operated mice. This decline in NF-kappaB activity is most likely due to posttranslational modifications such as deacetylation of p65. In parallel, cleavage of procaspase-3 is increased, whereas expression of NF-kappaB-dependent antiapoptotic genes Bcl-xL and c-IAP2 is suppressed upon sepsis induction. Interestingly, adoptive transfer of IkappaBalpha-deficient fetal liver stem cells into sublethally irradiated lymphopenic host mice reduced the decline in thymocyte survival, increased peripheral T cell numbers, and improved the mortality rate relative to wild-type reconstituted hosts after cecal ligation and puncture. In conclusion, lymphocyte-directed augmentation of canonical NF-kappaB ameliorates immunosuppression during murine sepsis. These data provide evidence for a new approach in sepsis therapy.     

Gene therapy with novel adeno-associated virus vectors substantially diminishes atherosclerosis in a murine model of familial hypercholesterolemia

BACKGROUND: Familial hypercholesterolemia is an inherited disease caused by mutations in the LDL receptor gene leading to severe hypercholesterolemia and atherosclerosis. The LDL receptor is predominantly expressed in the liver, making it a preferred target organ for somatic gene therapy. We recently isolated a new family of vectors based on adeno-associated viruses (AAVs) isolated from nonhuman primates, which enable efficient and stable transgene expression following in vivo gene delivery to liver. METHODS: Traditional vectors based on AAV serotype 2 and two novel AAVs from nonhuman primates, serotypes AAV7 and AAV8, were produced encoding for the human LDL receptor. Vectors were injected into the portal veins of LDL receptor deficient mice that were fed a high-fat diet to achieve severe pretreatment hypercholesterolemia. RESULTS: Animals receiving the novel AAV vectors realized nearly complete normalization of serum lipids and failed to develop the severe atherosclerosis that characterized the untreated animals; the AAV2 vector constructs demonstrated partial lipid correction and only a modest improvement in atherosclerosis. CONCLUSIONS: Using vectors based on novel nonhuman primate AAVs, which provide advantages in terms of efficiency, we were able to achieve a long-term correction of the metabolic defect in LDL receptor deficient mice.