Gary L. White

Lethal staphylococcus aureus-induced shock in primates : prevention of death with anti-TNF antibody

A successful experimental treatment for gram-positive sepsis to our knowledge has not been achieved. The objectives of this study were to develop a nonhuman primate model of lethal gram-positive sepsis employing the micro-organism Staphylococcus aureus and to determine the efficacy of treatment using monoclonal antibody (MAb) to tumor necrosis factor alpha (TNF). The antibody was administered intravenously, 15 mg/kg, 30 minutes after the beginning of a 2-hour infusion of S. aureus, 4 x 10(10) colony forming units/kilogram. The baboons infused with S. aureus demonstrated the release of the cytokines TNF and interleukin-6 (IL-6), but endotoxin was not observed in the plasma at any time. Treatment with antibody to TNF abolished the rise in serum TNF levels and reduced the increased levels of IL-6. Treatment with MAb to TNF prevented multiple organ failure and achieved permanent (> 7 day) survival of all baboons.

Bacterial determinants of persistent throat colonization and the associated immune response in a primate model of human group A streptococcal pharyngeal infection

Group A streptococcal (GAS) pharyngitis and the subsequent bacterial colonization of the human throat elicit an immune response that may precipitate acute rheumatic fever in a susceptible host. To study the bacterial determinants that influence throat colonization and induction of humoral immunity, we characterized the behavior of GAS strains in a baboon model. An M‐type 3 clinical isolate of GAS typical of strains that cause pharyngitis and invasive infection was recovered from the pharynx of six out of six baboons for at least 6 weeks after oral inoculation. By contrast, an isogenic mutant deficient in M protein failed to colonize most animals or was rapidly cleared. An isogenic mutant deficient in hyaluronic acid capsule colonized five out of six animals, but only persisted in the pharynx for 14–21 days. Colonized animals developed serum anti‐ streptolysin O (SLO) and anti‐M protein immunoglobulin (Ig)G. The kinetics of the antibody responses were similar to those seen after human infection. Peak titres increased with the duration of throat carriage. Colonization with GAS prevented recurrent colonization after challenge with the homologous wild‐type strain, but not after challenge with a strain of different M protein type. Early clearance of the M protein‐deficient strain was associated with increased susceptibility of this strain to phagocytic killing in non‐immune serum, whereas clearance of the acapsular strain was associated with increased susceptibility to phagocytic killing in the presence of specific antibody. These studies support critical and distinct effects of the GAS M protein and capsule on throat colonization and induction of humoral immunity in a model that reproduces important features of pharyngeal colonization and immune response following human infection.

Survival of primates in LD100 septic shock following steroid/antibiotic therapy.

Abstract This study was designed to determine the effect of steroid/antibiotic treatment on the survival of baboons subjected to LD100 Escherichia coli shock. Fourteen baboons (Papio c. cynocephalus), randomly divided into three groups, were anesthetized and administered 2-hr infusions of LD100 viable E. coli. Group A received E. coli alone; Group B was administered E. coli followed by infusions of both gentamicin sulfate (GS) (18 mg/kg) and methylprednisolone sodium succinate (MPSS) (75 mg/kg) during a 12-hr period. Group C was given E. coli plus GS (18 mg/kg) alone. Groups B and C baboons were also given GS intramuscularly, 4.5 mg/kg at 12 hr and twice daily for 3 days. Insensible fluid loss during the intial 12-hr period was replaced by minimal volumes of saline. Fully treated baboons (Group B) received steroid after 0.7 × 1010 organisms/kg body wt had been administered. All fully treated baboons survived; however, all animals of Groups A and C died within 42 hr. Systemic hypotension observed in every baboon within 2 hr was reversed in Group B animals. Hypoglycemia, hypoinsulinemia, anuria, and extensive adrenal pathology were prevented by steroid/antibiotic treatment. Serum creatinine and blood urea nitrogen concentrations increased in all baboons but returned to normal in the fully treated group. Increased survival may have been due in part to augmented antibacterial activity elicited by (a) improved peripheral distribution of the antibiotic and (b) stimulation of the bone marrow by the steroid. Findings demonstrate that the lethal pathophysiology of E. coli-induced shock is effectively prevented by combined steroid and antibiotic therapy.

PerR Confers Phagocytic Killing Resistance and Allows Pharyngeal Colonization by Group A Streptococcus

The peroxide response transcriptional regulator, PerR, is thought to contribute to virulence of group A Streptococcus (GAS); however, the specific mechanism through which it enhances adaptation for survival in the human host remains unknown. Here, we identify a critical role of PerR-regulated gene expression in GAS phagocytosis resistance and in virulence during pharyngeal infection. Deletion of perR in M-type 3 strain 003Sm was associated with reduced resistance to phagocytic killing in human blood and by murine macrophages in vitro. The increased phagocytic killing of the perR mutant was abrogated in the presence of the general oxidative burst inhibitor diphenyleneiodonium chloride (DPI), a result that suggests PerR-dependent gene expression counteracts the phagocyte oxidative burst. Moreover, an isogenic perR mutant was severely attenuated in a baboon model of GAS pharyngitis. In competitive infection experiments, the perR mutant was cleared from two animals at 24 h and from four of five animals by day 14, in sharp contrast to wild-type bacteria that persisted in the same five animals for 28 to 42 d. GAS genomic microarrays were used to compare wild-type and perR mutant transcriptomes in order to characterize the PerR regulon of GAS. These studies identified 42 PerR-dependent loci, the majority of which had not been previously recognized. Surprisingly, a large proportion of these loci are involved in sugar utilization and transport, in addition to oxidative stress adaptive responses and virulence. This finding suggests a novel role for PerR in mediating sugar uptake and utilization that, together with phagocytic killing resistance, may contribute to GAS fitness in the infected host. We conclude that PerR controls expression of a diverse regulon that enhances GAS resistance to phagocytic killing and allows adaptation for survival in the pharynx.

Increased survival with methylprednisolone treatment in canine endotoxin shock

Abstract The use of corticosteroids has been intensively studied for the treatment of endotoxin shock; however, there still remains much controversy over their use. This study was designed to determine the therapeutic value of treatment with methylprednisolone sodium succinate in the awake and anesthetized canine receiving LD 100 of Escherichia coli endotoxin by either intravenous slow infusion or bolus injection. Methylprednisolone (30 mg/kg) was administered initially at 15 min following the onset of endotoxin infusion and then at 90 min given a maintenance infusion of 15 mg/kg for 120 min. It was found that treatment with methylprednisolone significantly increased survival rate (83%) in dogs receiving LD 100 E. coli endotoxin by slow infusion in either the awake or anesthetized state. Both the 5-hr infusion and bolus injection of endotoxin produced a 100% mortality if steroid was not administered. Treatment with methylprednisolone did not alter the 100% mortality in the canine bolus-injected endotoxin shock model. Survival was associated with a normoglycemia and stabilized hematocrit, while death was accompanied by hypoglycemia and severe hemoconcentration.

Protective and antifecundity effects of Sm-p80 based DNA vaccine formulation against Schistosoma mansoni in a nonhuman primate model

Schistosomiasis is an important parasitic disease for which there is no available vaccine. We have focused on a functionally important antigen of Schistosoma mansoni, Sm-p80, as a vaccine candidate because of its consistent immunogenicity, protective potential and antifecundity effect observed in murine models; and for its pivotal role in the immune evasion process. In the present study we report that an Sm-p80-based DNA vaccine formulation confers 38% reduction in worm burden in a nonhuman primate model, the baboon (Papio anubis). Animals immunized with Sm-p80-pcDNA3 exhibited a decrease in egg production by 32%. Sm-p80 DNA elicited specific immune responses that include IgG; its subtypes IgG1 and IgG2; and IgM in vaccinated animals. Peripheral blood mononuclear cells (PBMCs) from immunized animals when stimulated in vitro with Sm-p80 produced appreciably more Th1 response enhancing cytokines (IL-2, IFN-gamma) than Th2 response enhancing cytokines (IL-4, IL-10). PBMCs produced appreciably more spot-forming units for INF-gamma than for IL-4 in enzyme-linked immunosorbent spot (ELISPOT) assays. Overall it appears that even though a mixed (Th1/Th2) type of humoral antibody response was generated following immunization with Sm-p80; the dominant protective immune response is Th1 type. These data reinforce the potential of Sm-p80 as an excellent vaccine candidate for schistosomiasis.

OspE-Related, OspF-Related, and Elp Lipoproteins Are Immunogenic in Baboons Experimentally Infected with Borrelia burgdorferi and in Human Lyme Disease Patients

ABSTRACT Presently, the rhesus macaque is the only nonhuman primate animal model utilized for the study of Lyme disease. While this animal model closely mimics human disease, rhesus macaques can harbor the herpes B virus, which is often lethal to humans; macaques also do not express the full complement of immunoglobulin G (IgG) subclasses found in humans. Conversely, baboons contain the full complement of IgG subclasses and do not harbor the herpes B virus. For these reasons, baboons have been increasingly utilized as the basis for models of infectious diseases and studies assessing the safety and immunogenicity of new vaccines. Here we analyzed the capability of baboons to become infected with Borrelia burgdorferi, the agent of Lyme disease. Combined culture and PCR analyses of tick- and syringe-infected animals indicated that baboons are a sufficient host for B. burgdorferi. Analysis of the antibody responses in infected baboons over a 48-week period revealed that antibodies are generated early during infection against many borrelial antigens, including the various OspE, OspF, and Elp paralogs that are encoded on the ubiquitous 32-kb circular plasmids (cp32s). By using the baboon sera generated by experimental infection it was determined that a combination of two cp32-encoded lipoproteins, OspE and ElpB1, resulted in highly specific and sensitive detection of B. burgdorferi infection. An expanded analysis, which included 39 different human Lyme disease patients, revealed that a combination of the OspE and ElpB1 lipoproteins could be the basis for a new serodiagnostic assay for Lyme disease. Importantly, this novel serodiagnostic test would be useful independent of prior OspA vaccination status.

Preclinical Prophylactic Efficacy Testing of Sm-p80–Based Vaccine in a Nonhuman Primate Model of Schistosoma mansoni Infection and Immunoglobulin G and E Responses to Sm-p80 in Human Serum Samples From an Area Where Schistosomiasis Is Endemic

The prophylactic efficacy of a schistosome antigen (Sm-p80) was tested in a nonhuman primate model, the baboon. Using a total of 28 baboons, different vaccination strategies were used including recombinant Sm-p80 protein formulated in Toll-like receptor 7 and Toll-like receptor 9 agonists, and DNA priming followed by boosting with protein plus adjuvants. Recombinant protein approaches provided levels of prophylactic efficacy of 52%-58%, whereas prime-boost approaches conferred 38%-47% protection in baboons. An appropriately balanced pro-inflammatory (T-helper 17 [Th17] and Th1) and anti-inflammatory (Th2) type of response was generated; the Th1 and Th17 types of immune responses appear to be indicative of increased prophylactic efficacy. Production and expression of several cytokines (interleukin 2 [IL-2], interferon γ, IL-12α, IL-1β, IL-6, and IL-22) were up-regulated in vaccinated animals. Human correlate studies revealed Sm-p80 reactivity with immunoglobulin G in human serum samples from schistosome-infected individuals. In addition, a complete lack of prevailing Sm-p80-specific immunoglobulin E in a high-risk or infected population was observed, thus minimizing the risk of hypersensitivity reaction following vaccination with Sm-p80 in humans. This study provided the proof of concept to move Sm-p80 forward into further preclinical development leading to human clinical trials.

Cellular and Molecular Effects of a Pulse Butyrate Regimen and New Inducers of Globin Gene Expression and Hematopoiesis

Abstract: Cooleys anemia is characterized by a deficiency of β‐globin chains, a relative excess of α‐globin chains, and consequent accelerated programmed death of developing erythroid cells in the bone marrow. Increasing expression of the γ‐globin genes to adequately balance excess α‐globin chains can ameliorate this disorder. Butyrates induce γ‐globin experimentally, but can also cause cell growth arrest with prolonged exposure or high concentrations, which in turn can accelerate apoptosis. To determine if these potentially opposing effects can be balanced to enhance therapeutic efficacy, an intermittent “pulsed” regimen of butyrate was evaluated. Following induction of γ‐globin mRNA and protein synthesis, total hemoglobin increased in β‐thalassemia patients by more than 2 g/dl above baseline, and Hb F increased above 20% in 5/8 sickle cell patients from baseline levels of 2% Hb F. Specific regulatory regions were identified in the γ‐ and β‐globin gene promoters to which new binding of transcription factors, including αCP2 (an activator of γ globin) occur during therapy solely in the butyrate‐responsive patients. Other compounds which induce γ globin, derivatives of acetic, phenoxyacetic, propionic, and cinnamic acids, and dimethylbutyrate, are under investigation. Some of these newer γ‐globin inducers (designated hemokines) provide better potential as therapeutics by also acting to increase hematopoietic cell viability and proliferation. Pharmacologic induction of expression of the endogenous γ‐globin genes is a realistic approach to therapy of the β‐globin disorders for many patients, with some effective agents available now and new therapeutics, with enhanced activities, under development.

Cross-species protection: Schistosoma mansoni Sm-p80 vaccine confers protection against Schistosoma haematobium in hamsters and baboons

The ability of the Schistosoma mansoni antigen, Sm-p80, to provide cross-species protection against Schistosoma haematobium challenge was evaluated in hamster and baboon models. Pronounced reduction in worm burden (48%) and in tissue egg load (64%) was observed in hamsters vaccinated with recombinant Sm-p80 admixed with glucopyranosyl lipid adjuvant-stable emulsion (GLA-SE). Similarly, in baboons, the Sm-p80/GLA-SE vaccine produced a 25% reduction in S. haematobium adult worms and decreased the egg load in the urinary bladder by 64%. A 40% and 53% reduction in fecal and urine egg output, respectively, was observed in vaccinated baboons. A balanced pro-inflammatory (Th17 and Th1) and Th2 type of response was generated after vaccination and appears indicative of augmented prophylactic efficacy. These data on cross-species protection coupled with the prophylactic, therapeutic and antifecundity efficacy against the homologous parasite, S. mansoni, reinforces Sm-p80 as a promising vaccine candidate. It is currently being prepared for GMP-compliant manufacture and for further pre-clinical development leading to human clinical trials. These results solidify the expectation that the Sm-p80 vaccine will provide relief for both the intestinal and the urinary schistosomiasis and thus will be greatly beneficial in reducing the overall burden of schistosomiasis.