Blockade of the G-CSF Receptor Is Protective in a Mouse Model of Renal Ischemia-Reperfusion Injury.

Ischemia-reperfusion injury (IRI) is a complex inflammatory process that detrimentally affects the function of transplanted organs. Neutrophils are important contributors to the pathogenesis of renal IRI. Signaling by G-CSF, a regulator of neutrophil development, trafficking, and function, plays a key role in several neutrophil-associated inflammatory disease models. In this study, we investigated whether targeting neutrophils with a neutralizing mAb to G-CSFR would reduce inflammation and protect against injury in a mouse model of warm renal IRI. Mice were treated with anti-G-CSFR 24 h prior to 22-min unilateral renal ischemia. Renal function and histology, complement activation, and expression of kidney injury markers, and inflammatory mediators were assessed 24 h after reperfusion. Treatment with anti-G-CSFR protected against renal IRI in a dose-dependent manner, significantly reducing serum creatinine and urea, tubular injury, neutrophil and macrophage infiltration, and complement activation (plasma C5a) and deposition (tissue C9). Renal expression of several proinflammatory genes (CXCL1/KC, CXCL2/MIP-2, MCP-1/CCL2, CXCR2, IL-6, ICAM-1, P-selectin, and C5aR) was suppressed by anti-G-CSFR, as was the level of circulating P-selectin and ICAM-1. Neutrophils in anti-G-CSFR-treated mice displayed lower levels of the chemokine receptor CXCR2, consistent with a reduced ability to traffic to inflammatory sites. Furthermore, whole transcriptome analysis using RNA sequencing showed that gene expression changes in IRI kidneys after anti-G-CSFR treatment were indistinguishable from sham-operated kidneys without IRI. Hence, anti-G-CSFR treatment prevented the development of IRI in the kidneys. Our results suggest G-CSFR blockade as a promising therapeutic approach to attenuate renal IRI.

A potent truncated form of human soluble CR1 is protective in a mouse model of renal ischemia-reperfusion injury.

The complement system is a potent mediator of ischemia-reperfusion injury (IRI), which detrimentally affects the function and survival of transplanted kidneys. Human complement receptor 1 (HuCR1) is an integral membrane protein that inhibits complement activation by blocking the convertases that activate C3 and C5. We have previously reported that CSL040, a truncated form of recombinant soluble HuCR1 (sHuCR1), has enhanced complement inhibitory activity and improved pharmacokinetic properties compared to the parent molecule. Here, we compared the capacity of CSL040 and full-length sHuCR1 to suppress complement-mediated organ damage in a mouse model of warm renal IRI. Mice were treated with two doses of CSL040 or sHuCR1, given 1 h prior to 22 min unilateral renal ischemia and again 3 h later. 24 h after reperfusion, mice treated with CSL040 were protected against warm renal IRI in a dose-dependent manner, with the highest dose of 60 mg/kg significantly reducing renal dysfunction, tubular injury, complement activation, endothelial damage, and leukocyte infiltration. In contrast, treatment with sHuCR1 at a molar equivalent dose to 60 mg/kg CSL040 did not confer significant protection. Our results identify CSL040 as a promising therapeutic candidate to attenuate renal IRI and demonstrate its superior efficacy over full-length sHuCR1 in vivo.

Complement-mediated Damage to the Glycocalyx Plays a Role in Renal Ischemia-reperfusion Injury in Mice.

BACKGROUND: Complement activation plays an important role in the pathogenesis of renal ischemia-reperfusion (IR) injury (IRI), but whether this involves damage to the vasculoprotective endothelial glycocalyx is not clear. We investigated the impact of complement activation on glycocalyx integrity and renal dysfunction in a mouse model of renal IRI. METHODS: Right nephrectomized male C57BL/6 mice were subjected to 22 minutes left renal ischemia and sacrificed 24 hours after reperfusion to analyze renal function, complement activation, glycocalyx damage, endothelial cell activation, inflammation, and infiltration of neutrophils and macrophages. RESULTS: Ischemia-reperfusion induced severe renal injury, manifested by significantly increased serum creatinine and urea, complement activation and deposition, loss of glycocalyx, endothelial activation, inflammation, and innate cell infiltration. Treatment with the anti-C5 antibody BB5.1 protected against IRI as indicated by significantly lower serum creatinine (P = 0.04) and urea (P = 0.003), tissue C3b/c and C9 deposition (both P = 0.004), plasma C3b (P = 0.001) and C5a (P = 0.006), endothelial vascular cell adhesion molecule-1 expression (P = 0.003), glycocalyx shedding (tissue heparan sulfate [P = 0.001], plasma syndecan-1 [P = 0.007], and hyaluronan [P = 0.02]), inflammation (high mobility group box-1 [P = 0.0003]), and tissue neutrophil (P = 0.0009) and macrophage (P = 0.004) infiltration. CONCLUSIONS: Together, our data confirm that the terminal pathway of complement activation plays a key role in renal IRI and demonstrate that the mechanism of injury involves shedding of the glycocalyx.

CD8+ T cells are associated with severe gastritis in Helicobacter pylori-infected mice in the absence of CD4+ T cells.

Helicobacter pylori infection results in the development of chronic gastritis, and CD4+ T cells are a major component of the gastric cellular infiltrate. To examine whether CD4+ T cells are important in initiating and maintaining H. pylori-induced gastritis, mice deficient in CD4+ T cells (B6.BM1.GK 1.5 mice [GK 1.5 mice]) were infected with H. pylori. We found that as in normal mice, H. pylori-specific antibodies, mostly of the immunoglobulin M isotype, developed in GK 1.5 mice but were unable to cure H. pylori infection. Further, while the stomachs of H. pylori-infected GK 1.5 mice were more heavily infiltrated with CD8+ T cells and B cells, mice deficient in both CD4+ and CD8+ T cells developed mild inflammation comparable to the level observed for C57BL/6 mice. These observations suggest that CD4+ T cells may play an important role in regulating or suppressing gastric CD8+ T cells which, in the absence of CD4+ T cells, may mediate more-severe disease. These studies have revealed a potentially important role for CD8+ T cells in the gastric disease resulting from H. pylori infection.

Macrophages are mediators of gastritis in acute Helicobacter pylori infection in C57BL/6 mice.

Helicobacter pylori is the etiological agent of human chronic gastritis, a condition seen as a precursor to the development of gastrointestinal ulcers or gastric cancer. This study utilized the murine model of chronic H. pylori infection to characterize the role of macrophages in the induction of specific immune responses and gastritis and in the control of the bacterial burden following H. pylori infection and vaccination. Drug-loaded liposomes were injected intravenously to deplete macrophages from C57BL/6 mice, and effective removal of CD11b+ cells from the spleens and stomachs of mice was confirmed by immunofluorescence microscopy. Transient elimination of macrophages from C57BL/6 mice during the early period of infection reduced the gastric pathology induced by H. pylori SS1 but did not affect the bacterial load in the stomach. These data suggest that macrophages are important to the severity of gastric inflammation during H. pylori infection.

Immunization Strategies Producing a Humoral IgG Immune Response against Devil Facial Tumor Disease in the Majority of Tasmanian Devils Destined for Wild Release.

Devil facial tumor disease (DFTD) is renowned for its successful evasion of the host immune system. Down regulation of the major histocompatabilty complex class I molecule (MHC-I) on the DFTD cells is a primary mechanism of immune escape. Immunization trials on captive Tasmanian devils have previously demonstrated that an immune response against DFTD can be induced, and that immune-mediated tumor regression can occur. However, these trials were limited by their small sample sizes. Here, we describe the results of two DFTD immunization trials on cohorts of devils prior to their wild release as part of the Tasmanian Government's Wild Devil Recovery project. 95% of the devils developed anti-DFTD antibody responses. Given the relatively large sample sizes of the trials (N = 19 and N = 33), these responses are likely to reflect those of the general devil population. DFTD cells manipulated to express MHC-I were used as the antigenic basis of the immunizations in both trials. Although the adjuvant composition and number of immunizations differed between trials, similar anti-DFTD antibody levels were obtained. The first trial comprised DFTD cells and the adjuvant combination of ISCOMATRIX™, polyIC, and CpG with up to four immunizations given at monthly intervals. This compared to the second trial whereby two immunizations comprising DFTD cells and the adjuvant combination ISCOMATRIX™, polyICLC (Hiltonol®) and imiquimod were given a month apart, providing a shorter and, therefore, more practical protocol. Both trials incorporated a booster immunization given up to 5 months after the primary course. A key finding was that devils in the second trial responded more quickly and maintained their antibody levels for longer compared to devils in the first trial. The different adjuvant combination incorporating the RNAase resistant polyICLC and imiquimod used in the second trial is likely to be responsible. The seroconversion in the majority of devils in these anti-DFTD immunization trials was remarkable, especially as DFTD is hallmarked by its immune evasion mechanisms. Microsatellite analyzes of MHC revealed that some MHC-I microsatellites correlated to stronger immune responses. These trials signify the first step in the long-term objective of releasing devils with immunity to DFTD into the wild.

Regression of devil facial tumour disease following immunotherapy in immunised Tasmanian devils.

Devil facial tumour disease (DFTD) is a transmissible cancer devastating the Tasmanian devil (Sarcophilus harrisii) population. The cancer cell is the 'infectious' agent transmitted as an allograft by biting. Animals usually die within a few months with no evidence of antibody or immune cell responses against the DFTD allograft. This lack of anti-tumour immunity is attributed to an absence of cell surface major histocompatibility complex (MHC)-I molecule expression. While the endangerment of the devil population precludes experimentation on large experimental groups, those examined in our study indicated that immunisation and immunotherapy with DFTD cells expressing surface MHC-I corresponded with effective anti-tumour responses. Tumour engraftment did not occur in one of the five immunised Tasmanian devils, and regression followed therapy of experimentally induced DFTD tumours in three Tasmanian devils. Regression correlated with immune cell infiltration and antibody responses against DFTD cells. These data support the concept that immunisation of devils with DFTD cancer cells can successfully induce humoral responses against DFTD and trigger immune-mediated regression of established tumours. Our findings support the feasibility of a protective DFTD vaccine and ultimately the preservation of the species.

ISCOMATRIX adjuvant for antigen delivery.

The immunostimulating complex, referred to as 'iscom', was first described by Morein et al. in 1984 as a novel structure for antigenic presentation of membrane proteins from enveloped viruses with potent immunomodulatory capability . Since this discovery, many vaccines have been tested in animal models showing the induction of both humoral and cellular immune responses . The ISCOMATRIX adjuvant is essentially the same structure as the iscom but without the incorporated antigen . Antigens can be formulated with the ISCOMATRIX adjuvant to produce ISCOMATRIX vaccines that can provide the same antigen presentation and immunomodulatory properties as the iscom but with much broader application as they are not limited to hydrophobic membrane proteins. Various ISCOMATRIX vaccines have been tested in animal models and more recently in human clinical trials . These studies have shown that the ISCOMATRIX adjuvant is safe and induces both humoral and cellular immune responses. The ability of the ISCOMATRIX adjuvant to induce these broad immune responses is due to the combination of antigen presentation by both MHC class I and class II pathways, and the powerful immunomodulatory capability of the saponin. Additionally, the ISCOMATRIX adjuvant is simple to manufacture and can be combined with a wide range of antigens making it suitable for the development of novel human vaccines.

NY-ESO-1 protein formulated in ISCOMATRIX adjuvant is a potent anticancer vaccine inducing both humoral and CD8+ t-cell-mediated immunity and protection against NY-ESO-1+ tumors.

NY-ESO-1 is a 180 amino-acid human tumor antigen expressed by many different tumor types and belongs to the family of "cancer-testis" antigens. In humans, NY-ESO-1 is one of the most immunogenic tumor antigens and NY-ESO-1 peptides have been shown to induce NY-ESO-1-specific CD8(+) CTLs capable of altering the natural course of NY-ESO-1-expressing tumors in cancer patients. Here we describe the preclinical immunogenicity and efficacy of NY-ESO-1 protein formulated with the ISCOMATRIX adjuvant (NY-ESO-1 vaccine). In vitro, the NY-ESO-1 vaccine was readily taken up by human monocyte-derived dendritic cells, and on maturation, these human monocyte-derived dendritic cells efficiently cross-presented HLA-A2-restricted epitopes to NY-ESO-1-specific CD8(+) T cells. In addition, epitopes of NY-ESO-1 protein were also presented on MHC class II molecules to NY-ESO-1-specific CD4(+) T cells. The NY-ESO-1 vaccine induced strong NY-ESO-1-specific IFN-gamma and IgG2a responses in C57BL/6 mice. Furthermore, the NY-ESO-1 vaccine induced NY-ESO-1-specific CD8(+) CTLs in HLA-A2 transgenic mice that were capable of lysing human HLA-A2(+) NY-ESO-1(+) tumor cells. Finally, C57BL/6 mice, immunized with the NY-ESO-1 vaccine, were protected against challenge with a B16 melanoma cell line expressing NY-ESO-1. These data illustrate that the NY-ESO-1 vaccine represents a potent therapeutic anticancer vaccine.

ISCOMATRIX™ adjuvant reduces mucosal tolerance for effective pulmonary vaccination against influenza.

While most pathogens infect via mucosal surfaces, most current vaccines are delivered by injection. This situation remains despite awareness of the potential benefits of mucosal delivery for inducing protection against mucosa-infecting pathogens. A major obstacle to the development of such vaccines is the paucity of safe and effective adjuvants that induce mucosal responses in non-rodents. Previously we demonstrated in sheep the potency of pulmonary-delivered influenza ISCOMATRIX™ vaccine, which induces both mucosal and systemic immunity, even with low antigen doses. In the current study, lung pre-exposure to influenza antigen alone significantly reduced the immune response to subsequent pulmonary-delivered influenza ISCOMATRIX™ vaccine. A single dose of influenza antigen, delivered to the lung without exogenous adjuvant, upregulated IL-10 expression in bronchoalveolar lavage cells and FOXP3 expression in lung tissue, suggestive of induction of a regulatory T cell (Treg) response. However, this effect was inhibited by addition of ISCOMATRIX™ adjuvant. Moreover, effective pulmonary immunization with influenza ISCOMATRIX™ vaccine was associated with a depletion of Treg markers within lung tissues. Lung exposure to influenza antigen induced a localized mucosal tolerance that reduced the efficacy of subsequent influenza ISCOMATRIX™ vaccination. An important role of ISCOMATRIX™ adjuvant in pulmonary vaccination appears to be the depletion of Treg in lung tissues. Pulmonary vaccination remains capable of inducing a strong immune response against mucosal pathogens, but likely requires an adjuvant to overcome mucosal tolerance. ISCOMATRIX™ appears to have considerable potential as a mucosal adjuvant for use in humans, a major unmet need in mucosal vaccine development.

Long-term antibody and immune memory response induced by pulmonary delivery of the influenza Iscomatrix vaccine.

Pulmonary delivery of an influenza Iscomatrix adjuvant vaccine induces a strong systemic and mucosal antibody response. Since an influenza vaccine needs to induce immunological memory that lasts at least 1 year for utility in humans, we examined the longevity of the immune response induced by such a pulmonary vaccination, with and without antigen challenge. Sheep were vaccinated in the deep lung with an influenza Iscomatrix vaccine, and serum and lung antibody levels were quantified for up to 1 year. The immune memory response to these vaccinations was determined following antigen challenge via lung delivery of influenza antigen at 6 months and 1 year postvaccination. Pulmonary vaccination of sheep with the influenza Iscomatrix vaccine induced antigen-specific antibodies in both sera and lungs that were detectable until 6 months postimmunization. Importantly, a memory recall response following antigenic challenge was detected at 12 months post-lung vaccination, including the induction of functional antibodies with hemagglutination inhibition activity. Pulmonary delivery of an influenza Iscomatrix vaccine induces a long-lived influenza virus-specific antibody and memory response of suitable length for annual vaccination against influenza.

Control of pandemic (H1N1) 2009 influenza virus infection of ferret lungs by non-adjuvant-containing pandemic and seasonal vaccines.

The pandemic H1N1 2009 influenza virus caused relatively mild disease in most infected people but some suffered extensively from primary lung infection, many more than would have occurred with seasonal influenza infection. Early commercially available pandemic H1N1 vaccines did not contain adjuvant, as did many of the subsequent vaccines, and could not stop infection with the pandemic virus in vaccinated ferrets. Nevertheless, we showed that virus loads in the lungs were greatly diminished in ferrets vaccinated once with an unadjuvanted pandemic vaccine and challenged with 10(6)EID(50) wildtype A/California/07/2009 (H1N1). In addition, a single inoculation with seasonal vaccine showed beneficial reduction in pandemic pulmonary virus loads in the absence of any detectable cross-reactive serological responses. Ferrets primed with either seasonal or pandemic vaccine and then boosted with pandemic vaccine also showed less extensive lung infection when challenged with a tenfold higher dose of pandemic virus. These results implicate non-classical protective mechanisms that prevent severe pulmonary disease but not viral shedding and imply that particular non-adjuvanted vaccines may have retained the ability to induce these responses.

Single dose intranasal immunization with ISCOMATRIX vaccines to elicit antibody-mediated clearance of influenza virus requires delivery to the lower respiratory tract.

The effectiveness of single dose, intranasally delivered vaccines comprising detergent-disrupted inactivated influenza virus (split virus) and ISCOMATRIX adjuvant was examined in mice. Vaccines formulated with adjuvant required 10- to 100-fold less split virus antigen to induce pulmonary protection following viral challenge when compared to vaccines containing split virus alone. Furthermore, those formulated with ISCOMATRIX adjuvant elicited specific antibody in serum, saliva, vaginal, nasal and lung fluids when delivered to the entire respiratory tract. No specific antibody was detected in serum or mucosal samples, however, when the same vaccines were delivered using a procedure that restricted the inoculum to the nasal passages. Good protective responses can thus be achieved with only a single intranasal inoculation of influenza vaccine formulated with adjuvant, providing the vaccine can access sites of immune induction in the lower respiratory tract.

Targeting subcapsular antigens for prevention of Klebsiella pneumoniae infections.

Vaccination strategies against Klebsiella pneumoniae have largely focussed on the polysaccharide capsule. However, the large number and high prevalence of individual capsular serotypes limits the widespread applicability of capsule-based vaccines. This study establishes that immunization with purified LPS can protect mice against lethal challenge with K. pneumoniae, and that subcapsular antibodies directed against purified LPS can be used to treat and/or prevent experimental K. pneumoniae infection in mice. This approach offers potential for prophylaxis and/or therapy against drug-resistant strains of K. pneumoniae.

Secondary acylation of Klebsiella pneumoniae lipopolysaccharide contributes to sensitivity to antibacterial peptides.

Klebsiella pneumoniae is an important cause of nosocomial Gram-negative sepsis. Lipopolysaccharide (LPS) is considered to be a major virulence determinant of this encapsulated bacterium and most mutations to the lipid A anchor of LPS are conditionally lethal to the bacterium. We studied the role of LPS acylation in K. pneumoniae disease pathogenesis by using a mutation of lpxM (msbB/waaN), which encodes the enzyme responsible for late secondary acylation of immature lipid A molecules. A K. pneumoniae B5055 (K2:O1) lpxM mutant was found to be attenuated for growth in the lungs in a mouse pneumonia model leading to reduced lethality of the bacterium. B5055DeltalpxM exhibited similar sensitivity to phagocytosis or complement-mediated lysis than B5055, unlike the non-encapsulated mutant B5055nm. In vitro, B5055DeltalpxM showed increased permeability of the outer membrane and an increased susceptibility to certain antibacterial peptides suggesting that in vivo attenuation may be due in part to sensitivity to antibacterial peptides present in the lungs of BALB/c mice. These data support the view that lipopolysaccharide acylation plays a important role in providing Gram-negative bacteria some resistance to structural and innate defenses and especially the antibacterial properties of detergents (e.g. bile) and cationic defensins.

ISCOM-based vaccines: the second decade.

The immunostimulating complex or 'iscom' was first described 20 years ago as an antigen delivery system with powerful immunostimulating activity. Iscoms are cage-like structures, typically 40 nm in diameter, that are comprised of antigen, cholesterol, phospholipid and saponin. ISCOM-based vaccines have been shown to promote both antibody and cellular immune responses in a variety of experimental animal models. This review focuses on the evaluation of ISCOM-based vaccines in animals over the past 10 years, as well as examining the progress that has been achieved in the development of human vaccines based on ISCOM adjuvant technology.

Association of antigens to ISCOMATRIX adjuvant using metal chelation leads to improved CTL responses.

The association of antigen with ISCOMATRIX trade mark adjuvant has been shown to be important for the optimal induction of cytotoxic T lymphocyte (CTL) responses. Here, we describe a simple broadly applicable method for associating recombinant proteins with hexa-histidine tags to ISCOMATRIX trade mark adjuvant utilising metal-affinity chelating interactions. The metal chelation binding step can be performed in a wide range of buffers, including commonly used denaturants such as urea, which makes it an ideal strategy for formulating proteins which are otherwise insoluble. Following association of protein with the chelating ISCOMATRIX trade mark adjuvant, the denaturant can be removed. Further, we show enhanced CTL responses with a protein-associated chelating ISCOMATRIX trade mark vaccine compared to a non-associated ISCOMATRIX trade mark vaccine.

Targeting gene expression to endothelium in transgenic animals: a comparison of the human ICAM-2, PECAM-1 and endoglin promoters.

It is highly likely that successful pig-to-human xenotransplantation of vascularized organs will require genetic modification of the donor pig, and in particular of donor vascular endothelium. Promoters are generally tested in transgenic mice before generating transgenic pigs. Several promoters have been used to drive endothelial cell-specific expression in mice but none have yet been tested in pigs. We compared the promoters of three human genes that are predominantly expressed in vascular endothelium: intercellular adhesion molecule 2 (ICAM-2), platelet endothelial cell adhesion molecule 1 (PECAM-1) and endoglin. Expression of human complement regulatory proteins (hCRPs), directed by each of the promoters in mice, was largely restricted to vascular endothelium and leukocyte subpopulations. However, expression from the PECAM-1 promoter was weak in liver and non-uniform in the small vessels of heart, kidney, and lung. Conversely, expression from the endoglin promoter was consistently strong in the small vessels of these organs but was absent in larger vessels. The ICAM-2 promoter, which produced strong and uniform endothelial expression in all organs examined, was therefore used to generate hCRP transgenic pigs. Leukocytes from 57 pigs containing at least one intact transgene were tested for transgene expression by flow cytometry. Forty-seven of these transgenic pigs were further analyzed by immunohistochemical staining of liver biopsies, and 18 by staining of heart and kidney sections. Only two of the pigs showed expression, which appeared to be restricted to vascular endothelium in heart and kidney but was markedly weaker than in transgenic mice produced with the same batch of DNA. Thus, in this case, promoter performance in mice and pigs was not equivalent. The weak expression driven by the human ICAM-2 promoter in pigs relative to mice suggests the need for additional regulatory elements to achieve species-specific gene expression in pigs.

Phase 1 study of HPV16-specific immunotherapy with E6E7 fusion protein and ISCOMATRIX adjuvant in women with cervical intraepithelial neoplasia.

PURPOSE: Persistent infection of cervical epithelium with "high risk" human papillomavirus (HPV) results in cervical intraepithelial neoplasia (CIN) from which squamous cancer of the cervix can arise. A study was undertaken to evaluate the safety and immunogenicity of an HPV16 immunotherapeutic consisting of a mixture of HPV16 E6E7 fusion protein and ISCOMATRIX adjuvant (HPV16 Immunotherapeutic) for patients with CIN. EXPERIMENTAL DESIGN: Patients with CIN (n = 31) were recruited to a randomised blinded placebo controlled dose ranging study of immunotherapy. RESULTS: Immunotherapy was well tolerated. Immunised subjects developed HPV16 E6E7 specific immunity. Antibody, delayed type hypersensitivity, in vitro cytokine release, and CD8 T cell responses to E6 and E7 proteins were each significantly greater in the immunised subjects than in placebo recipients. Loss of HPV16 DNA from the cervix was observed in some vaccine and placebo recipients. CONCLUSIONS: The HPV16 Immunotherapeutic comprising HPV16E6E7 fusion protein and ISCOMATRIX adjuvant is safe and induces vaccine antigen specific cell mediated immunity.