Encapsulation of an EP67-Conjugated CTL Peptide Vaccine in Nanoscale Biodegradable Particles Increases the Efficacy of Respiratory Immunization and Affects the Magnitude and Memory Subsets of Vaccine-Generated Mucosal and Systemic CD8+ T Cells in a Diameter-Dependent Manner.

The diameter of biodegradable particles used to coencapsulate immunostimulants and subunit vaccines affects the magnitude of memory CD8+ T cells generated by systemic immunization. Possible effects on the magnitude of CD8+ T cells generated by mucosal immunization or memory subsets that potentially correlate more strongly with protection against certain pathogens, however, are unknown. In this study, we conjugated our novel host-derived mucosal immunostimulant, EP67, to the protective MCMV CTL epitope, pp89, through a lysosomal protease-labile double arginine linker (pp89-RR-EP67) and encapsulated in PLGA 50:50 micro- or nanoparticles. We then compared total magnitude, effector/central memory (CD127/KRLG1/CD62L), and IFN-γ/TNF-α/IL-2 secreting subsets of pp89-specific CD8+ T cells as well as protection of naive female BALB/c mice against primary respiratory infection with MCMV 21 days after respiratory immunization. We found that decreasing the diameter of encapsulating particle from ∼5.4 µm to ∼350 nm (i) increased the magnitude of pp89-specific CD8+ T cells in the lungs and spleen; (ii) partially changed CD127/KLRG1 effector memory subsets in the lungs but not the spleen; (iii) changed CD127/KRLG1/CD62L effector/central memory subsets in the spleen; (iv) changed pp89-responsive IFN-γ/TNF-α/IL-2 secreting subsets in the lungs and spleen; (v) did not affect the extent to which encapsulation increased efficacy against primary MCMV respiratory infection over unencapsulated pp89-RR-EP67. Thus, although not observed under our current experimental conditions with MCMV, varying the diameter of nanoscale biodegradable particles may increase the efficacy of mucosal immunization with coencapsulated immunostimulant/subunit vaccines against certain pathogens by selectively increasing memory subset(s) of CD8+ T cells that correlate the strongest with protection.

Preliminary evidence that the novel host-derived immunostimulant EP67 can act as a mucosal adjuvant.

EP67 is a complement component 5a (C5a)-derived peptide agonist of the C5a receptor (CD88) that selectively activates DCs over neutrophils. Systemic administration of EP67 covalently attached to peptides, proteins, or attenuated pathogens generates TH1-biased immunogen-specific humoral and cellular immune responses with little inflammation. Furthermore, intranasal administration of EP67 alone increases the proportion of activated APCs in the airways. As such, we hypothesized that EP67 can act as a mucosal adjuvant. Intranasal immunization with an EP67-conjugated CTL peptide vaccine against protective MCMV epitopes M84 and pp89 increased protection of naïve female BALB/c mice against primary respiratory infection with salivary gland-derived MCMV and generated higher proportions of epitope responsive and long-lived memory precursor effector cells (MPEC) in the lungs and spleen compared to an inactive, scrambled EP67-conjugated CTL peptide vaccine and vehicle alone. Thus, EP67 may be an effective adjuvant for mucosal vaccines and warrants further study.

Targeting macrophage activation for the prevention and treatment of Staphylococcus aureus biofilm infections.

Biofilm infections often lead to significant morbidity due to their chronicity and recalcitrance to antibiotics. We have demonstrated that methicillin-resistant Staphylococcus aureus (MRSA) biofilms can evade macrophage (MΦ) antibacterial effector mechanisms by skewing MΦs toward an alternatively activated M2 phenotype. To overcome this immune evasion, we have used two complementary approaches. In the first, a proinflammatory milieu was elicited by local administration of classically activated M1 MΦs and in the second by treatment with the C5a receptor (CD88) agonist EP67, which invokes MΦ proinflammatory activity. Early administration of M1-activated MΦs or EP67 significantly attenuated biofilm formation in a mouse model of MRSA catheter-associated infection. Several proinflammatory mediators were significantly elevated in biofilm-infected tissues from MΦ- and EP67-treated animals, revealing effective reprogramming of the biofilm environment to a proinflammatory milieu. A requirement for MΦ proinflammatory activity was demonstrated by the fact that transfer of MyD88-deficient MΦs had minimal impact on biofilm growth. Likewise, neutrophil administration had no effect on biofilm formation. Treatment of established biofilm infections with M1-activated MΦs also significantly reduced catheter-associated biofilm burdens compared with antibiotic treatment. Collectively, these results demonstrate that targeting MΦ proinflammatory activity can overcome the local immune inhibitory environment created during biofilm infections and represents a novel therapeutic strategy.

A novel C5a-derived immunobiotic peptide reduces Streptococcus agalactiae colonization through targeted bacterial killing.

Streptococcus agalactiae (group B Streptococcus [GBS]) is a Gram-positive bacterium that colonizes the cervicovaginal tract in approximately 25% of healthy women. Although colonization is asymptomatic, GBS can be vertically transmitted to newborns peripartum, causing severe disease such as pneumonia and meningitis. Current prophylaxis, consisting of late gestation screening and intrapartum antibiotics, has failed to completely prevent transmission, and GBS remains a leading cause of neonatal sepsis and meningitis in the United States. Lack of an effective vaccine and emerging antibiotic resistance necessitate exploring novel therapeutic strategies. We have employed a host-directed immunomodulatory therapy using a novel peptide, known as EP67, derived from the C-terminal region of human complement component C5a. Previously, we have demonstrated in vivo that EP67 engagement of the C5a receptor (CD88) effectively limits staphylococcal infection by promoting cytokine release and neutrophil infiltration. Here, using our established mouse model of GBS vaginal colonization, we observed that EP67 treatment results in rapid clearance of GBS from the murine vagina. However, this was not dependent on functional neutrophil recruitment or CD88 signaling, as EP67 treatment reduced the vaginal bacterial load in mice lacking CD88 or the major neutrophil receptor CXCr2. Interestingly, we found that EP67 inhibits GBS growth in vitro and in vivo and that antibacterial activity was specific to Streptococcus species. Our work establishes that EP67-mediated clearance of GBS is likely due to direct bacterial killing rather than to enhanced immune stimulation. We conclude that EP67 may have potential as a therapeutic to control GBS vaginal colonization.

Treatment with a C5aR antagonist decreases pathology and enhances behavioral performance in murine models of Alzheimer's disease.

Alzheimer's disease (AD) is an age-related dementia, characterized by amyloid plaques, neurofibrillary tangles, neuroinflammation, and neuronal loss in the brain. Components of the complement system, known to produce a local inflammatory reaction, are associated with the plaques and tangles in AD brain, and thus a role for complement-mediated inflammation in the acceleration or progression of disease has been proposed. A complement activation product, C5a, is known to recruit and activate microglia and astrocytes in vitro by activation of a G protein-coupled cell-surface C5aR. Here, oral delivery of a cyclic hexapeptide C5a receptor antagonist (PMX205) for 2-3 mo resulted in substantial reduction of pathological markers such as fibrillar amyloid deposits (49-62%) and activated glia (42-68%) in two mouse models of AD. The reduction in pathology was correlated with improvements in a passive avoidance behavioral task in Tg2576 mice. In 3xTg mice, PMX205 also significantly reduced hyperphosphorylated tau (69%). These data provide the first evidence that inhibition of a proinflammatory receptor-mediated function of the complement cascade (i.e., C5aR) can interfere with neuroinflammation and neurodegeneration in AD rodent models, suggesting a novel therapeutic target for reducing pathology and improving cognitive function in human AD patients.

Microglial C5aR (CD88) expression correlates with amyloid-beta deposition in murine models of Alzheimer's disease.

Alzheimer's disease (AD), a progressive neurodegenerative disease characterized by the accumulation of amyloid-beta protein and neuronal loss, is the leading cause of age-related dementia in the world today. The disease is also associated with neuroinflammation, robust activation of astrocytes and microglia, and evidence of activation of the complement system, localized with both fibrillar amyloid-beta (fAbeta) plaques and tangles. The observations are consistent with a complement-dependent component of AD progression. We have previously shown that inhibition of the major complement receptor for C5a (CD88) with the antagonist PMX205 results in a significant reduction in pathology in two mouse models of AD. To further characterize the role of complement in AD-related neuroinflammation, we examined the age- and disease-associated expression of CD88 in brain of transgenic mouse models of AD and the influence of PMX205 on the presence of various complement activation products using flow cytometry, western blot, and immunohistochemistry. CD88 was found to be up-regulated in microglia, in the immediate vicinity of amyloid plaques. While thioflavine plaque load and glial recruitment is significantly reduced after treatment with PMX205, C1q remains co-localized with fAbeta plaques and C3 is still expressed by the recruited astrocytes. Thus, with PMX205, potentially beneficial activities of these early complement components may remain intact, while detrimental activities resulting from C5a-CD88 interaction are inhibited. This further supports the targeted inhibition of specific complement mediated activities as an approach for AD therapy.

Targeted Amino Acid Substitution Overcomes Scale-Up Challenges with the Human C5a-Derived Decapeptide Immunostimulant EP67.

EP67 is a second-generation, human C5a-derived decapeptide agonist of C5a receptor 1 (C5aR1/CD88) that selectively activates mononuclear phagocytes over neutrophils to potentiate protective innate and adaptive immune responses while potentially minimizing neutrophil-mediated toxicity. Pro7 and N-methyl-Leu8 (Me-Leu8) amino acid residues within EP67 likely induce backbone structural changes that increase potency and selective activation of mononuclear phagocytes over neutrophils versus first-generation EP54. The low coupling efficiency between Pro7 and Me-Leu8 and challenging purification by HPLC, however, greatly increase scale-up costs of EP67 for clinical use. Thus, the goal of this study was to determine whether replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes (cyclohexylalanine7 and/or leucine8) sufficiently preserves EP67 activity in primary human mononuclear phagocytes and neutrophils. We found that EP67 analogues had similar potency, efficacy, and selective activation of mononuclear phagocytes over neutrophils. Thus, replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes is a suitable strategy to overcome scale-up challenges with EP67.

Single-step conjugation of bioactive peptides to proteins via a self-contained succinimidyl bis-arylhydrazone.

This paper describes a method for a single-step, site-specific conjugation of bioactive peptides to proteins that exploits the monitoring advantages provided by the unique UV signature absorbance of a bis-arylhydrazone. The utility of this method is demonstrated by the conjugation of a decapeptide molecular adjuvant, YSFKDMP(MeL)aR (EP67), to two test proteins, ovalbumin (OVA) and bovine serum albumin (BSA), and to proteins expressed on intact influenza virons and fungal arthroconidia (spores) of Coccidioides. Conjugation is accomplished with a version of EP67 in which its N-terminus is modified with succinimidyl-4-benzoylhydrazino-nicotinamide (S4BHyNic) (peptide 7), thus enabling conjugation to these large entities via formation of amide bonds with surface-exposed amino groups. The presence of the strongly absorbing bis-arylhydrazone S4BHyNic (ε(354 nm) = 29 000 L mol(-1) cm(-1)) allows for determination of EP67-to-protein molar substitution ratios (MSR), which are in good agreement with the MSRs determined by amino acid analysis. Conjugation to OVA does not compromise the ability of EP67 to engage C5a receptor bearing antigen presenting cells (APC) as measured by the EP67-mediated release of interleukin-6 (IL-6) from APCs. Mice immunized with the resulting OVA-EP67 vaccine conjugate produce high serum titers of OVA-specific IgG antibodies relative to OVA alone. Also, the conjugation of EP67 does not affect the surface integrity of influenza virons or the biological viability of Coccidioides spores. This method of conjugating bioactive peptides to proteins and other large biological entities may represent a convenient and effective way of generating various bioconjugates for use in mechanistic studies or novel therapeutic entities such as EP67-containing vaccines.

The role of complement in innate, adaptive and eosinophil-dependent immunity to the nematode Nippostrongylus brasiliensis.

Complement may be important for immunity to infection with parasitic helminths, by promoting the recruitment of leukocytes to infected tissues and by modulating the function of cytotoxic effector leukocytes. However, the importance of complement in vivo during helminth infection is poorly understood. In this study, mice lacking classical (C1q-deficient), alternative (factor B-deficient) or all pathways of complement activation (C3-deficient) were used to assess the role of complement in immunity to the nematode Nippostrongylus brasiliensis. Double-mutant complement-deficient/IL-5 transgenic (Tg) mice were used to determine if complement is required for the strong eosinophil-dependent resistance to this parasite. Complement activation on larvae (C3 deposition), extracellular eosinophil peroxidase activity, larval aggregation and eosinophil recruitment to the skin 30 min post-injection (p.i.) of larvae were reduced in factor B-deficient mice. Inhibition of the C5a receptor with the antagonist PMX53 impaired eosinophil and neutrophil recruitment to the skin. C3 deposition on larvae was minimal by 150 min p.i. and at this time cell adherence, larval aggregation, eosinophil recruitment and degranulation were complement-independent. Factor B and C3 deficiency were associated with higher lung larval burdens in primary infections. Complement-deficient/IL-5 Tg mice were highly resistant to N. brasiliensis, suggesting that eosinophils can limit infection in a complement-independent manner. Potent secondary immunity was similarly complement-independent. In conclusion, although the alternative pathway is important for parasite recognition and leukocyte recruitment early in N. brasiliensis infections, the parasite soon becomes resistant to complement and other factors can compensate to promote eosinophil-dependent immunity.

Surface conjugation of EP67 to biodegradable nanoparticles increases the generation of long-lived mucosal and systemic memory T-cells by encapsulated protein vaccine after respiratory immunization and subsequent T-cell-mediated protection against respiratory infection.

Encapsulation of protein vaccines in biodegradable nanoparticles (NP) increases T-cell expansion after mucosal immunization but requires incorporating a suitable immunostimulant to increase long-lived memory T-cells. EP67 is a clinically viable, host-derived peptide agonist of the C5a receptor that selectively activates antigen presenting cells over neutrophils. We previously found that encapsulating EP67-conjugated CTL peptide vaccines in NP increases long-lived memory subsets of CTL after respiratory immunization. Thus, we hypothesized that alternatively conjugating EP67 to the NP surface can increase long-lived mucosal and systemic memory T-cells generated by encapsulated protein vaccines. We found that respiratory immunization of naïve female C57BL/6 mice with LPS-free ovalbumin (OVA) encapsulated in PLGA 50:50 NP (∼380 nm diameter) surface-conjugated with ∼0.1 wt% EP67 through 2 kDa PEG linkers (i) increased T-cell expansion and long-lived memory subsets of OVA323-339-specific CD4+ and OVA257-264-specific CD8a+ T-cells in the lungs (CD44HI/CD127/KLRG1) and spleen (CD44HI/CD127/KLRG1/CD62L) and (ii) decreased peak CFU of OVA-expressing L. monocytogenes (LM-OVA) in the lungs, liver, and spleen after respiratory challenge vs. encapsulation in unmodified NP. Thus, conjugating EP67 to the NP surface is one approach to increase the generation of long-lived mucosal and systemic memory T-cells by encapsulated protein vaccines after respiratory immunization.

A conformationally-biased, response-selective agonist of C5a acts as a molecular adjuvant by modulating antigen processing and presentation activities of human dendritic cells.

A partial mechanism by which a conformationally-biased, response-selective agonist of complement component C5a, Tyr-Ser-Phe-Lys-Pro-Met-Pro-Leu-D-Ala-Arg or YSFKPMPLaR (EP54), acts as a molecular adjuvant is presented by showing the manner in which this peptide engages human dendritic cells (DC). Confocal microscopy was used to show that fluorescent-labeled EP54 (0.2 microM) and fluorescent-labeled B and T cell epitopes attached to EP54 (i.e., EP54-containing vaccines, 0.2 microM) were internalized by human DCs well within 30 min of exposure. After 24 h of exposure, EP54 and the B and T cell epitopes of the EP54-containing vaccines (20 microM) were presented on the DC surface in the context of HLA-ABC and HLA-DR determinants. Also, exposure of DCs to EP54 (50 microg/ml) induced the activation of genes specific for the Th1 cytokines IL-6, IL-12, INFgamma, and TNFalpha as well as the Th2 cytokine IL-4. Internalization, HLA expression, and cytokine gene activation were not observed in the presence of the inactive, scrambled EP54 constructs arguing that these effects of EP54 are mediated predominately via C5a receptors on the DC surface.

Role of polymorphonuclear leukocytes, nitric oxide synthase, and cyclooxygenase in vascular permeability changes induced by C5a agonist peptides.

Tumor responses to radioimmunotherapy combined with peptide agonists of human C5a anaphylatoxin such as GCGYSFKPMPLaR (C5aAP) are two- to four-fold better, depending on the dose of C5aAP, than responses to radioimmunotherapy alone. The enhanced tumor vascular permeability (VP) is the key factor responsible for this improvement. These studies were designed to identify the sequence of events leading to the improved extravasation of immunoglobulin in response to C5aAP. The VP changes were measured in mice after administration of C5aAP alongside of various mediators. The depletion of circulating polymorphonuclear neutrophils (PMN) in mice abolished the C5aAP-induced VP increase. Blocking of P-selectin also returned VP to its basal levels after the C5aAP treatment, indicating that C5aAP-induced VP changes are initiated by interactions of C5aAP with PMNs. Aminoguanidine, an inducible nitric oxide synthase (NOS) inhibitor, given before C5aAP returned VP to control levels. N(omega)-nitro-L-arginine methyl ester, a nonselective NOS inhibitor, had a marginal effect on the activity of C5aAP. Indomethacin, a nonselective cyclooxygenase inhibitor, suppressed C5aAP-induced increases in VP, whereas N-(2-cyclohexyloxy-4-nitrophenyl)-methanesulfonamide, a selective cyclooxygenase-2 inhibitor, was active only at high doses. While C5aAP given i.p. did not alter tumor uptake of (125)I-B72.3, the i.v. administration resulted in approximately 40% increase, confirming the prerequisite interaction of C5aAP with PMNs. The sequence leading to the increased VP appears to be initiated by the interaction of C5aAP with C5a receptor expressed on PMNs followed by binding to endothelial cells of blood vessels. The interaction with P-selectin is responsible for the initiation of the nitric oxide cascade as evidenced by inducible NOS activation. Additionally, prostaglandins are required for expression of the full magnitude of the C5aAP activities.

Potentiation of radioimmunotherapy with response-selective peptide agonist of human C5a.

UNLABELLED: Physiologic barriers to the delivery of macromolecules to solid tumors are a major obstacle to the clinical success of radioimmunotherapy (RIT). Only a small fraction of the injected dose of the radiolabeled monoclonal antibody (mAb) localizes at the tumor site. This situation worsens as the tumor burden increases. It is hypothesized that improvements to RIT of adenocarcinoma can be realized by inclusion of vasoactive agents, in particular agents able to increase the vascular permeability of tumor capillaries. In these studies, a response-selective peptide agonist of human C5a, GCGYSFKPMPLaR (AP), was used to transiently increase tumor vascular permeability in an effort to improve RIT of solid tumors. METHODS: Athymic mice xenografted with human colorectal adenocarcinoma LS174T were treated intravenously with low doses (9.25 MBq) of 131I-labeled mAb B72.3 in combination with various intravenous doses of AP. The progression of the disease or the loss of >20% body weight was taken as the endpoint. Biodistribution and tumor uptake kinetics were studied in the same tumor-antibody system. RESULTS: The uptake of 125I-B72.3 in LS174T xenografts increased in a dose-dependent manner with an apparent maximal effect between 3 and 6 h after intravenous administration of AP. Augmenting the dose of 9.25 MBq 131I-B72.3 with a single administration of 0.1 mg AP delayed tumor growth nearly 2-fold; the tumor quadrupling time (T(q)) was 14.2 +/- 3.3 d for 131I-B72.3 alone versus 26.0 +/- 3.6 d for 131I-B72.3 plus 0.1 mg AP (P < 0.001). An additional dose of 0.1 mg AP 24 h after 131I-B72.3 further improved the therapeutic outcome (T(q) = 48.5 +/- 7.9 d; P < 0.001) and resulted in several cases of tumor regression. CONCLUSION: The inclusion of agonist peptides of human C5a in the RIT scheme results in improved tumor responses without any manifest side effects.

Immunization to nicotine with a peptide-based vaccine composed of a conformationally biased agonist of C5a as a molecular adjuvant.

This paper describes the synthesis of a nicotine hapten (Nic) that possesses a carboxyl sidearm functional group allowing for conjugation to a peptide via amide bond formation. Nic was attached to the N-terminal amino group of a 19-residue peptide composed of a conformationally biased agonist of human C5a (YSFKPMPLaR), which is used as a molecular adjuvant and a B cell epitope of human MUC1 glycoprotein (YKQGGFLGL) to yield a peptide-based nicotine vaccine, NicYKQGGFLGLYSFKPMPLaR. Rats immunized with this vaccine were significantly less sensitive to behavioral effects (a Pavlovian discrimination task) induced by their exposure to high concentrations of nicotine (0.4 mg/kg) relative to their non-vaccinated counterparts. The attenuation of these nicotine-induced behavioral effects emanated from the presence of nicotine-specific antibodies (Abs) that were present in the sera of vaccinated rats even after their repeated exposure to high concentrations of nicotine during the time required to perform the behavioral assays. These results suggest that immunization with NicYKQGGFLGLYSFKPMPLaR in the absence of adjuvant is an effective means of inducing a nicotine-specific Ab response, which is capable of attenuating nicotine-induced behavioral/psychoactive effects.

Protein kinase C-alpha mediates cigarette smoke extract- and complement factor 5a-stimulated interleukin-8 release in human bronchial epithelial cells.

BACKGROUND: Cigarette smoke extract (CSE) activates protein kinase C (PKC) and augments complement factor 5a (C5a)-stimulated release of the proinflammatory cytokine IL-8 in human bronchial epithelial cells (HBEC). We hypothesized that PKC activation by alternative PKC activators will also mediate C5a-stimulated IL-8 release in HBEC. METHODS: HBEC were treated with phorbol myristate acetate (100 ng/mL), calcium ionophore A23187 (2 nM), or 10 nM cholesterol-3-sulfate in the presence or absence of C5a. Interleukin-8 (IL-8) release was measured by enzyme-linked immunoadsorbent assay. RESULTS: IL-8 release by PKC activators alone was significantly higher than in unstimulated cells and was further augmented in the presence of C5a. Preincubation with the PKC inhibitor calphostin C (1 microM) significantly suppressed IL-8 release in HBEC treated with CSE and C5a. Preincubation with 10 microM TMB-8 (an intracellular calcium sequester) also significantly suppressed IL-8 release in CSE- and C5a-treated HBEC, suggesting that intracellular calcium is required for CSE- and C5a-mediated IL-8 release. When HBEC were preincubated with 30 nM of the PKCbeta-specific inhibitor LY363196, CSE- and C5a-mediated IL-8 release was not inhibited. However, with higher concentrations of LY363196 (>600 nM), which exceeds the IC50 for PKCbeta greater than 100 fold, CSE- and C5a-mediated IL-8 release was significantly suppressed. Preincubation of HBEC with 100 nM of Gö 6976, a specific PKCalpha inhibitor, significantly inhibited CSE- and C5a-mediated stimulation of IL-8 release. CONCLUSIONS: Collectively, these data suggest that PKC activators in addition to CSE augment C5a-stimulated IL-8 release from HBEC and that CSE and C5a stimulate IL-8 release in HBEC by activating the calcium-dependent PKCalpha isoform.

Treatment with the C5a receptor/CD88 antagonist PMX205 reduces inflammation in a murine model of allergic asthma.

Allergic asthma is a chronic inflammatory airway disease arising from an aberrant immune response following exposure to environmental stimuli in genetically susceptible persons. The complement component 5 (C5)/C5a Receptor (C5aR/CD88) signaling pathway has been implicated in both experimental allergic asthma and human asthmatic disease. Targeting the C5a/C5aR signaling pathway in rodent models has been shown to either enhance or reduce allergic asthma consequences. Treatment with a recombinant humanized monoclonal antibody directed against C5 has shown unclear results in patients with asthma. The objective of this proof-of-concept animal study was to determine whether the low molecular weight C5aR peptidomimetic antagonist, PMX205, would reduce experimental allergic asthma consequences in mice. PMX205 or vehicle control was administered subcutaneously to BALB/c mice prior to and during standard ovalbumin (OVA) allergen sensitization and aerosolized challenge phases. PMX205 substantially reduced OVA-induced total cell (60%), neutrophil (66%) and eosinophil (65%) influxes in lavage fluid sampling. There were also significant reductions in OVA-induced lavage fluid IL-13 protein and lung Th2 cytokine gene expression with PMX205 administration. PMX205 treatment also diminished OVA-induced lung parenchyma cellular infiltration. PMX205 administration did not reduce OVA-induced serum IgE levels or epithelial mucous/goblet cell generation. There was no evidence of toxicity observed with PMX205 treatment in saline or OVA-challenged animals. These data provide evidence that pharmacologic blockade of C5aR by a low molecular weight antagonist (PMX205) reduces airway inflammatory cell and cytokine responses in experimental allergic asthma, and suggests that PMX205 might represent a novel therapeutic agent for reducing asthmatic outcomes.

An agonist of human complement fragment C5a enhances vaccine immunity against Coccidioides infection.

Coccidioides is a fungal pathogen and causative agent of a human respiratory disease against which no clinical vaccine exists. In this study we evaluated a novel vaccine adjuvant referred to as EP67, which is a peptide agonist of the biologically active C-terminal region of human complement component C5a. The EP67 peptide was conjugated to live spores of an attenuated vaccine strain (ΔT) of Coccidioides posadasii. The non-conjugated ΔT vaccine provided partial protection to BALB/c mice against coccidioidomycosis. In this report we compared the protective efficacy of the ΔT-EP67 conjugate to the ΔT vaccine in BALB/c mice. Animals immunized subcutaneously with the ΔT-EP67 vaccine showed significant increase in survival and decrease in fungal burden over 75 days postchallenge. Increased pulmonary infiltration of dendritic cells and macrophages was observed on day 7 postchallenge but marked decrease in neutrophil numbers had occurred by 11 days. The reduced influx of neutrophils may have contributed to the observed reduction of inflammatory pathology. Mice immunized with the ΔT-EP67 vaccine also revealed enhanced expression of MHC II molecules on the surface of antigen presenting cells, and in vitro recall assays of immune splenocytes showed elevated Th1- and Th17-type cytokine production. The latter correlated with a marked increase in lung infiltration of IFN-γ- and IL-17-producing CD4(+) T cells. Elevated expression of T-bet and RORc transcription factors in ΔT-EP67-vaccinated mice indicated the promotion of Th1 and Th17 cell differentiation. Higher titers of Coccidioides antigen-specific IgG1 and IgG2a were detected in mice immunized with the EP67-conjugated versus the non-conjugated vaccine. These combined results suggest that the EP67 adjuvant enhances protective efficacy of the live vaccine by augmentation of T-cell immunity, especially through Th1- and Th17-mediated responses to Coccidioides infection.

Innate immune induction and influenza protection elicited by a response-selective agonist of human C5a.

The anaphylatoxin C5a is an especially potent mediator of both local and systemic inflammation. However, C5a also plays an essential role in mucosal host defense against bacterial, viral, and fungal infection. We have developed a response-selective agonist of human C5a, termed EP67, which retains the immunoenhancing activity of C5a at the expense of its inflammatory, anaphylagenic properties. EP67 insufflation results in the rapid induction of pulmonary cytokines and chemokines. This is followed by an influx of innate immune effector cells, including neutrophils, NK cells, and dendritic cells. EP67 exhibits both prophylactic and therapeutic protection when tested in a murine model of influenza A infection. Mice treated with EP67 within a twenty-four hour window of non-lethal infection were significantly protected from influenza-induced weight loss. Furthermore, EP67 delivered twenty-four hours after lethal infection completely blocked influenza-induced mortality (0% vs. 100% survival). Since protection based on innate immune induction is not restricted to any specific pathogen, EP67 may well prove equally efficacious against a wide variety of possible viral, bacterial, and fungal pathogens. Such a strategy could be used to stop the worldwide spread of emergent respiratory diseases, including but not limited to novel strains of influenza.

Tumor-specific peptide-based vaccines containing the conformationally biased, response-selective C5a agonists EP54 and EP67 protect against aggressive large B cell lymphoma in a syngeneic murine model.

Vaccines to large B cell lymphoma were made by the covalent attachment of an epitope from the gp70 glycoprotein (SSWDFITV) to the N-termini of the conformationally biased, response-selective C5a agonists EP54 (YSFKPMPLaR) and EP67 (YSFKDMP(MeL)aR). Syngeneic Balb/c mice were immunized with these EP54/EP67-containing vaccines and challenged with a lethal dose of the highly liver metastatic and gp70-expressing lymphoma cell line RAW117-H10 to evaluate the ability of these vaccines to induce protective immune outcomes. All mice immunized with SSWDFITVRRYSFKPMPLaR (Vaccine 2) and SSWDFITVRRYSFKDMP(MeL)aR (Vaccine 3) were protected to a lethal challenge of RAW117-H10 lymphoma (>170 days survival) and exhibited no lymphoma infiltration or solid tumor nodules in the liver relative to unvaccinated controls (<18 days survival). Vaccines 2 and 3 contained the protease-sensitive double-Arg (RR) linker sequence between the epitope and the EP54/EP67 moieties in order to provide a site for intracellular proteases to separate the epitope from the EP54/EP67 moieties once internalized by the APC and, consequently, enhance epitope presentation in the context of MHC I/II. These protected mice exhibited an immune outcome consistent with increased involvement of CD8(+) and/or CD4(+) T lymphocytes relative to controls and mice that did not survive or showed low survival rates as with Vaccines 1 and 4, which lacked the RR linker sequence. CD8(+) T lymphocytes activated in response to Vaccines 2 and 3 express cytotoxic specificity for gp70-expressing RAW117-H10 lymphoma cells, but not antigen-irrelevant MDA-MB231A human breast cancer cells. Results are discussed against the backdrop of the ability of EP54/EP67 to selectively target antigens to and activate C5a receptor-bearing antigen presenting cells and the prospects of using such vaccines therapeutically against lymphoma and other cancers.