Intranasal challenge with B. pertussis leads to more severe disease manifestations in mice than aerosol challenge

The murine Bordetella pertussis challenge model has been utilized in preclinical research for decades. Currently, inconsistent methodologies are employed by researchers across the globe, making it difficult to compare findings. The objective of this work was to utilize the CD-1 mouse model with two routes of challenge, intranasal and aerosol administration of B. pertussis, to understand the differences in disease manifestation elicited via each route. We observed that both routes of B. pertussis challenge result in dose-dependent colonization of the respiratory tract, but overall, intranasal challenge led to higher bacterial burden in the nasal lavage, trachea, and lung. Furthermore, high dose intranasal challenge results in induction of leukocytosis and pro-inflammatory cytokine responses compared to aerosol challenge. These data highlight crucial differences in B. pertussis challenge routes that should be considered during experimental design.

Development of an anti-Pseudomonas aeruginosa therapeutic monoclonal antibody WVDC-5244

The rise of antimicrobial-resistant bacterial infections is a crucial health concern in the 21st century. In particular, antibiotic-resistant Pseudomonas aeruginosa causes difficult-to-treat infections associated with high morbidity and mortality. Unfortunately, the number of effective therapeutic interventions against antimicrobial-resistant P. aeruginosa infections continues to decline. Therefore, discovery and development of alternative treatments are necessary. Here, we present pre-clinical efficacy studies on an anti-P. aeruginosa therapeutic monoclonal antibody. Using hybridoma technology, we generated a monoclonal antibody and characterized its binding to P. aeruginosa in vitro using ELISA and fluorescence correlation spectroscopy. We also characterized its function in vitro and in vivo against P. aeruginosa. The anti-P. aeruginosa antibody (WVDC-5244) bound P. aeruginosa clinical strains of various serotypes in vitro, even in the presence of alginate exopolysaccharide. In addition, WVDC-5244 induced opsonophagocytic killing of P. aeruginosa in vitro in J774.1 murine macrophage, and complement-mediated killing. In a mouse model of acute pneumonia, prophylactic administration of WVDC-5244 resulted in an improvement of clinical disease manifestations and reduction of P. aeruginosa burden in the respiratory tract compared to the control groups. This study provides promising pre-clinical efficacy data on a new monoclonal antibody with therapeutic potential for P. aeruginosa infections.

Bordetella pertussis whole cell immunization protects against Pseudomonas aeruginosa infections

Whole cell vaccines are complex mixtures of antigens, immunogens, and sometimes adjuvants that can trigger potent and protective immune responses. In some instances, such as whole cell Bordetella pertussis vaccination, the immune response to vaccination extends beyond the pathogen the vaccine was intended for and contributes to protection against other clinically significant pathogens. In this study, we describe how B. pertussis whole cell vaccination protects mice against acute pneumonia caused by Pseudomonas aeruginosa. Using ELISA and western blot, we identified that B. pertussis whole cell vaccination induces production of antibodies that bind to lab-adapted and clinical strains of P. aeruginosa, regardless of immunization route or adjuvant used. The cross-reactive antigens were identified using immunoprecipitation, mass spectrometry, and subsequent immunoblotting. We determined that B. pertussis GroEL and OmpA present in the B. pertussis whole cell vaccine led to production of antibodies against P. aeruginosa GroEL and OprF, respectively. Finally, we showed that recombinant B. pertussis OmpA was sufficient to induce protection against P. aeruginosa acute murine pneumonia. This study highlights the potential for use of B. pertussis OmpA as a vaccine antigen for prevention of P. aeruginosa infection, and the potential of broadly protective antigens for vaccine development.

Long-Term Analysis of Pertussis Vaccine Immunity to Identify Potential Markers of Vaccine-Induced Memory Associated With Whole Cell But Not Acellular Pertussis Immunization in Mice

Over two decades ago acellular pertussis vaccines (aP) replaced whole cell pertussis vaccines (wP) in several countries. Since then, a resurgence in pertussis has been observed, which is hypothesized to be linked, in part, to waning immunity. To better understand why waning immunity occurs, we developed a long-term outbred CD1 mouse model to conduct the longest murine pertussis vaccine studies to date, spanning out to 532 days post primary immunization. Vaccine-induced memory results from follicular responses and germinal center formation; therefore, cell populations and cytokines involved with memory were measured alongside protection from challenge. Both aP and wP immunization elicit protection from intranasal challenge by decreasing bacterial burden in both the upper and lower airways, and by generation of pertussis specific antibody responses in mice. Responses to wP vaccination were characterized by a significant increase in T follicular helper cells in the draining lymph nodes and CXCL13 levels in sera compared to aP mice. In addition, a population of B. pertussis⁺ memory B cells was found to be unique to wP vaccinated mice. This population peaked post-boost, and was measurable out to day 365 post-vaccination. Anti-B. pertussis and anti-pertussis toxoid antibody secreting cells increased one day after boost and remained high at day 532. The data suggest that follicular responses, and in particular CXCL13 levels in sera, could be monitored in pre-clinical and clinical studies for the development of the next-generation pertussis vaccines.

Innate and Adaptive Immune Responses against Bordetella pertussis and Pseudomonas aeruginosa in a Murine Model of Mucosal Vaccination against Respiratory Infection

Whole cell vaccines are frequently the first generation of vaccines tested for pathogens and can inform the design of subsequent acellular or subunit vaccines. For respiratory pathogens, administration of vaccines at the mucosal surface can facilitate the generation of a localized mucosal immune response. Here, we examined the innate and vaccine-induced immune responses to infection by two respiratory pathogens: Bordetella pertussis and Pseudomonas aeruginosa. In a model of intranasal administration of whole cell vaccines (WCVs) with the adjuvant curdlan, we examined local and systemic immune responses following infection. These studies showed that intranasal vaccination with a WCV led to a reduction of the bacterial burden in the airways of animals infected with the respective pathogen. However, there were unique changes in the cytokines produced, cells recruited, and inflammation at the site of infection. Both mucosal vaccinations induced antibodies that bind the target pathogen, but linear regression and principal component analysis revealed that protection from these pathogens is not solely related to antibody titer. Protection from P. aeruginosa correlated to a reduction in lung weight, blood lymphocytes and neutrophils, and the cytokines IL-6, TNF-α, KC/GRO, and IL-10, and promotion of serum IgG antibodies and the cytokine IFN-γ in the lung. Protection from B. pertussis infection correlated strongly with increased anti-B-pertussis serum IgG antibodies. These findings reveal valuable correlates of protection for mucosal vaccination that can be used for further development of both B. pertussis and P. aeruginosa vaccines.

Identifying mechanistic correlates of protection against Pseudomonas aeruginosa in an acute lung pneumonia model

Pseudomonas aeruginosa (Pa) is an opportunistic Gram-negative pathogen that can lead to life-threatening pulmonary infections. Several promising vaccine candidates against Pa evaluated in clinical trials. However, there is still no commercial vaccine available against this pathogen, in part due to a lack of clarity of protective correlates of vaccine–induced immunity. To elucidate correlates of protection against Pa, we used an intranasal whole–cell Pa vaccine adjuvanted with curdlan WCV in a murine vaccination and challenge model. Immunization with WCV significantly decreased the bacterial burden and lung edema after Pa challenge. We found that WCV immunization leads to a significant increase in Th17 cellular immune response and Pa–specific serum IgG and IgA titers compared to naive animals. To identify mechanistic correlates of protection, we performed anti–CD4, – CD8, and –CD20 antibody mediated depletions prior to vaccination and challenge. Depletion of these populations did not affect the response to challenge in naive animals. Interestingly, we observed that depletion of B cells but not CD8+ or CD4+ T cells during WCV priming resulted in loss of protection against Pa. Furthermore, passive immunization of WCV sera was sufficient to protect naive mice against Pa. Taken together, vaccine-mediated humoral immune response was the critical component of immunity against Pa in acute lung pneumonia model. This study suggests that adjuvants stimulating humoral immune response may be used to enhance the efficacy of vaccine candidates against Pa.

Two for one: Identification of P. aeruginosa and B. pertussis Cross-species Antigens

Development of effective vaccines requires logical design and formulation of two main components: antigens and adjuvants. Some compounds, called immunogens, can assume both of these roles. Notably, Bordetella pertussis (Bp) and some of its antigenic products have been found to adjuvant immune responses to other vaccines or vaccine components. We chose to explore this ability by using B. pertussis and pertussis toxin as adjuvants for a whole cell vaccine (WCV) against Pseudomonas aeruginosa (Pa). Pa is a highly antibiotic resistant Gram-negative opportunistic pathogen for which there are no approved vaccines or immunotherapies. We formulated vaccines containing Pa with Bp or pertussis toxin to determine if these components could modulate the immune response to PaWCV, as measured by quantification of bacterial burden and immune cell response after an acute pneumonia challenge. We determined that these additions to the PaWCV were associated with increased clearance of bacteria after challenge and increased Pa-binding immunoglobulins in the blood and airway. Additionally, we determined that the BpWCV alone was sufficient to induce protection from acute Pa infection. This correlated with production of antibodies that bind Pa, indicating that there is at least one cross-reactive antigen that could be providing protection. Through utilization of immunoblotting of protein fractions of Pa and mass spectroscopy, we identified this protective antigen. It will be used to formulate a subunit vaccine and tested for efficacy in protection from Pseudomonas infection. This type of cross-protection is novel within the field and could lead to the identification of a protective antigen against P. aeruginosa in B. pertussis.

Intranasal Peptide-Based FpvA-KLH Conjugate Vaccine Protects Mice From Pseudomonas aeruginosa Acute Murine Pneumonia

Pseudomonas aeruginosa is an opportunistic pathogen causing acute and chronic respiratory infections associated with morbidity and mortality, especially in patients with cystic fibrosis. Vaccination against P. aeruginosa before colonization may be a solution against these infections and improve the quality of life of at-risk patients. To develop a vaccine against P. aeruginosa, we formulated a novel peptide-based P. aeruginosa subunit vaccine based on the extracellular regions of one of its major siderophore receptors, FpvA. We evaluated the effectiveness and immunogenicity of the FpvA peptides conjugated to keyhole limpet hemocyanin (KLH) with the adjuvant curdlan in a murine vaccination and challenge model. Immunization with the FpvA-KLH vaccine decreased the bacterial burden and lung edema after P. aeruginosa challenge. Vaccination with FpvA-KLH lead to antigen-specific IgG and IgM antibodies in sera, and IgA antibodies in lung supernatant. FpvA-KLH immunized mice had an increase in recruitment of CD11b⁺ dendritic cells as well as resident memory CD4⁺ T cells in the lungs compared to non-vaccinated challenged mice. Splenocytes isolated from vaccinated animals showed that the FpvA-KLH vaccine with the adjuvant curdlan induces antigen-specific IL-17 production and leads to a Th17 type of immune response. These results indicate that the intranasal FpvA-KLH conjugate vaccine can elicit both mucosal and systemic immune responses. These observations suggest that the intranasal peptide-based FpvA-KLH conjugate vaccine with curdlan is a potential vaccine candidate against P. aeruginosa pneumonia.

Bordetella pertussis Whole Cell Immunization, Unlike Acellular Immunization, Mimics Naïve Infection by Driving Hematopoietic Stem and Progenitor Cell Expansion in Mice

Hematopoietic stem and progenitor cell (HSPC) compartments are altered to direct immune responses to infection. Their roles during immunization are not well-described. To elucidate mechanisms for waning immunity following immunization with acellular vaccines (ACVs) against Bordetella pertussis (Bp), we tested the hypothesis that immunization with Bp ACVs and whole cell vaccines (WCVs) differ in directing the HSPC characteristics and immune cell development patterns that ultimately contribute to the types and quantities of cells produced to fight infection. Our data demonstrate that compared to control and ACV-immunized CD-1 mice, immunization with an efficacious WCV drives expansion of hematopoietic multipotent progenitor cells (MPPs), increases circulating white blood cells (WBCs), and alters the size and composition of lymphoid organs. In addition to MPPs, common lymphoid progenitor (CLP) proportions increase in the bone marrow of WCV-immunized mice, while B220⁺ cell proportions decrease. Upon subsequent infection, increases in maturing B cell populations are striking in WCV-immunized mice. RNAseq analyses of HSPCs revealed that WCV and ACV-immunized mice vastly differ in developing VDJ gene segment diversity. Moreover, gene set enrichment analyses demonstrate WCV-immunized mice exhibit unique gene signatures that suggest roles for interferon (IFN) induced gene expression. Also observed in naïve infection, these IFN stimulated gene (ISG) signatures point toward roles in cell survival, cell cycle, autophagy, and antigen processing and presentation. Taken together, these findings underscore the impact of vaccine antigen and adjuvant content on skewing and/or priming HSPC populations for immune response.

Injection of human umbilical tissue-derived cells into the nucleus pulposus alters the course of intervertebral disc degeneration in vivo

BACKGROUND CONTEXT

Patients often present to spine clinic with evidence of intervertebral disc degeneration (IDD). If conservative management fails, a safe and effective injection directly into the disc might be preferable to the risks and morbidity of surgery.

PURPOSE

To determine whether injecting human umbilical tissue-derived cells (hUTC) into the nucleus pulposus (NP) might improve the course of IDD.

DESIGN

Prospective, randomized, blinded placebo-controlled in vivo study.

PATIENT SAMPLE

Skeletally mature New Zealand white rabbits.

OUTCOME MEASURES

Degree of IDD based on magnetic resonance imaging (MRI), biomechanics, and histology.

METHODS

Thirty skeletally mature New Zealand white rabbits were used in a previously validated rabbit annulotomy model for IDD. Discs L2-L3, L3-L4, and L4-L5 were surgically exposed and punctured to induce degeneration and then 3 weeks later the same discs were injected with hUTC with or without a hydrogel carrier. Serial MRIs obtained at 0, 3, 6, and 12 weeks were analyzed for evidence of degeneration qualitatively and quantitatively via NP area and MRI Index. The rabbits were sacrificed at 12 weeks and discs L4-L5 were analyzed histologically. The L3-L4 discs were fixed to a robotic arm and subjected to uniaxial compression, and viscoelastic displacement curves were generated.

RESULTS

Qualitatively, the MRIs demonstrated no evidence of degeneration in the control group over the course of 12 weeks. The punctured group yielded MRIs with the evidence of disc height loss and darkening, suggestive of degeneration. The three treatment groups (cells alone, carrier alone, or cells+carrier) generated MRIs with less qualitative evidence of degeneration than the punctured group. MRI Index and area for the cell and the cell+carrier groups were significantly distinct from the punctured group at 12 weeks. The carrier group generated MRI data that fell between control and punctured values but failed to reach a statistically significant difference from the punctured values. There were no statistically significant MRI differences among the three treatment groups. The treated groups also demonstrated viscoelastic properties that were distinct from the control and punctured values, with the cell curve more similar to the punctured curve and the carrier curve and carrier+cells curve more similar to the control curve (although no creep differences achieved statistical significance). There was some histological evidence of improved cellularity and disc architecture in the treated discs compared with the punctured discs.

CONCLUSIONS

Treatment of degenerating rabbit intervertebral discs with hUTC in a hydrogel carrier solution might help restore the MRI, histological, and biomechanical properties toward those of nondegenerated controls. Treatment with cells in saline or a hydrogel carrier devoid of cells also might help restore some imaging, architectural, and physical properties to the degenerating disc. These data support the potential use of therapeutic cells in the treatment of disc degeneration.

Injection of AAV2-BMP2 and AAV2-TIMP1 into the nucleus pulposus slows the course of intervertebral disc degeneration in an in vivo rabbit model

BACKGROUND CONTEXT

Intervertebral disc degeneration (IDD) is a common cause of back pain. Patients who fail conservative management may face the morbidity of surgery. Alternative treatment modalities could have a significant impact on disease progression and patients' quality of life.

PURPOSE

To determine if the injection of a virus vector carrying a therapeutic gene directly into the nucleus pulposus improves the course of IDD.

STUDY DESIGN

Prospective randomized controlled animal study.

METHODS

Thirty-four skeletally mature New Zealand white rabbits were used. In the treatment group, L2-L3, L3-L4, and L4-L5 discs were punctured in accordance with a previously validated rabbit annulotomy model for IDD and then subsequently treated with adeno-associated virus serotype 2 (AAV2) vector carrying genes for either bone morphogenetic protein 2 (BMP2) or tissue inhibitor of metalloproteinase 1 (TIMP1). A nonoperative control group, nonpunctured sham surgical group, and punctured control group were also evaluated. Serial magnetic resonance imaging (MRI) studies at 0, 6, and 12 weeks were obtained, and a validated MRI analysis program was used to quantify degeneration. The rabbits were sacrificed at 12 weeks, and L4-L5 discs were analyzed histologically. Viscoelastic properties of the L3-L4 discs were analyzed using uniaxial load-normalized displacement testing. Creep curves were mathematically modeled according to a previously validated two-phase exponential model. Serum samples obtained at 0, 6, and 12 weeks were assayed for biochemical evidence of degeneration.

RESULTS

The punctured group demonstrated MRI and histologic evidence of degeneration as expected. The treatment groups demonstrated less MRI and histologic evidence of degeneration than the punctured group. The serum biochemical marker C-telopeptide of collagen type II increased rapidly in the punctured group, but the treated groups returned to control values by 12 weeks. The treatment groups demonstrated several viscoelastic properties that were distinct from control and punctured values.

CONCLUSIONS

Treatment of punctured rabbit intervertebral discs with AAV2-BMP2 or AAV2-TIMP1 helps delay degenerative changes, as seen on MRI, histologic sampling, serum biochemical analysis, and biomechanical testing. Although data from animal models should be extrapolated to the human condition with caution, this study supports the potential use of gene therapy for the treatment of IDD.

Autologous bone marrow-derived rat mesenchymal stem cells promote PDX-1 and insulin expression in the islets, alter T cell cytokine pattern and preserve regulatory T cells in the periphery and induce sustained normoglycemia

Cell-based therapies offer considerable promise for prevention or cure of diabetes. We explored the potential of autologous, self-renewing, mesenchymal stem cells (MSC) as a clinically-applicable approach to promote glucose homeostasis. In vitro-expanded syngeneic bone marrow-derived MSC were administered following or prior to diabetes induction into a rat model of streptozotocin-induced beta cell injury. MSC were CD45(-)/CD44(+)/CD54(+)/CD90(+)/CD106(+). MSC spontaneously secreted IL-6, HGF, TGF-beta1 and expressed high levels of SDF-1 and low levels of VEGF, IL-1beta and PGE(2), but no EGF, insulin or glucagon. MSC homed to the pancreas and this therapy allowed for enhanced insulin secretion and sustained normoglycemia. Interestingly, immunohistochemistry demonstrated that, the islets from MSC-treated rats expressed high levels of PDX-1 and that these cells were also positive for insulin staining. In addition, peripheral T cells from MSC-treated rats exhibited a shift toward IL-10/IL-13 production and higher frequencies of CD4(+)/CD8(+) Foxp3(+) T cells compared to the PBS-treated rats. These data suggest that the bioactive factors secreted by MSC establish a tissue microenvironment that supports beta cell activation/survival in the pancreas. In addition, because of anti-inflammatory and immunoregulatory effects of MSC on T cells, this work can lead to clinical trial of autologous MSC to prevent/cure type-1 diabetes.

Expression of the fat-1 gene diminishes prostate cancer growth in vivo through enhancing apoptosis and inhibiting GSK-3 beta phosphorylation

Epidemiologic studies inclusively indicate that "unhealthy" dietary fat intake is one of the potential risk factors for cancer. In dietary fat, there are two types of polyunsaturated fatty acids (PUFA), omega-3 (n-3) and omega-6 (n-6). Numerous studies support that the ratio of n-6/n-3 affects tumorigenesis. It was reported that adenoviral transfer of the fat-1 gene, which converts n-6 to n-3, into breast and lung cancer cells had an antitumor effect in vitro. However, the effects of the fat-1 gene expression on tumor growth in vivo have not been studied and the mechanisms remain unclear. Accordingly, prostate cancer DU145 and PC3 cells were transfected with either the fat-1 gene or a control vector. The cells that expressed the fat-1 gene had a lower n-6/n-3 PUFA ratio compared with the cells that expressed the control vector. The fat-1 gene expression significantly inhibited prostate cancer cell proliferation and invasion in vitro. The fat-1 and control vector-transfected prostate cancer cells were s.c. implanted into severe combined immunodeficient mice for 6 weeks. The fat-1 gene expression significantly diminished tumor growth in vivo, but the control vector had no effect. Finally, we evaluated signaling pathways that may be important for fat-1 gene function. Administration of n-3 PUFA induced caspase-3-mediated prostate cancer cell apoptosis in vitro. The fat-1 gene expression inhibited prostate cancer cell proliferation via reduction of GSK-3beta phosphorylation and subsequent down-regulation of both beta-catenin and cyclin D1. These results suggest that fat-1 gene transfer directly into tumor cells could be used as a novel therapeutic approach.

Cloned Transgenic Swine Via In Vitro Production and Cryopreservation1

It has been notoriously difficult to successfully cryopreserve swine embryos, a task that has been even more difficult for in vitro-produced embryos. The first reproducible method of cryopreserving in vivo-produced swine embryos was after centrifugation and removal of the lipids. Here we report the adaptation of a similar process that permits the cryopreservation of in vitro-produced somatic cell nuclear transfer (SCNT) swine embryos. These embryos develop to the blastocyst stage and survive cryopreservation. Transfer of 163 cryopreserved SCNT embryos to two surrogates produced 10 piglets. Application of this technique may permit national and international movement of cloned transgenic swine embryos, storage until a suitable surrogate is available, or the long-term frozen storage of valuable genetics.

Generation of cloned transgenic pigs rich in omega-3 fatty acids

Meat products are generally low in omega-3 (n-3) fatty acids, which are beneficial to human health. We describe the generation of cloned pigs that express a humanized Caenorhabditis elegans gene, fat-1, encoding an n-3 fatty acid desaturase. The hfat-1 transgenic pigs produce high levels of n-3 fatty acids from n-6 analogs, and their tissues have a significantly reduced ratio of n-6/n-3 fatty acids (P < 0.001).