Biofilm and planktonic pneumococci demonstrate disparate immunoreactivity to human convalescent sera

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus pneumoniae </it>(the pneumococcus) is the leading cause of otitis media, community-acquired pneumonia (CAP), sepsis, and meningitis. It is now evident that <it>S. pneumoniae </it>forms biofilms during nasopharyngeal colonization; the former which facilitates persistence, the latter, a prerequisite for subsequent development of invasive disease. Proteomic evaluation of <it>S. pneumoniae </it>suggests the antigen profile available for host-recognition is altered as a consequence of biofilm growth. This has potentially meaningful implications in regards to adaptive immunity and protection from disseminated disease. We therefore examined the antigen profile of biofilm and planktonic pneumococcal cell lysates, tested their reactivity with human convalescent sera and that generated against biofilm pneumococci, and examined whether immunization with biofilm pneumococci protected mice against infectious challenge.</p> <p>Results</p> <p>Biofilm pneumococci have dramatically altered protein profiles versus their planktonic counterparts. During invasive disease the humoral immune response is skewed towards the planktonic protein profile. Immunization with biofilm bacteria does not elicit a strong-cross-reactive humoral response against planktonic bacteria nor confer resistance against challenge with a virulent isolate from another serotype. We identified numerous proteins, including Pneumococcal serine-rich repeat protein (PsrP), which may serve as a protective antigens against both colonization and invasive disease.</p> <p>Conclusion</p> <p>Differential protein production by planktonic and biofilm pneumococci provides a potential explanation for why individuals remain susceptible to invasive disease despite previous colonization events. These findings also strongly suggest that differential protein production during colonization and disease be considered during the selection of antigens for any future protein vaccine.</p

Novel strategies to enhance vaccine immunity against coccidioidomycosis

Coccidioidomycosis is a potentially life-threatening respiratory mycosis endemic to the Americas and caused by inhalation of spores produced by the molds Coccidioides immitis and C. posadasii

Impairment of early fracture healing by skeletal muscle trauma is restored by FK506

BACKGROUND: Heightened local inflammation due to muscle trauma or disease is associated with impaired bone regeneration. METHODS: We hypothesized that FK506, an FDA approved immunomodulatory compound with neurotrophic and osteogenic effects, will rescue the early phase of fracture healing which is impaired by concomitant muscle trauma in male (~4 months old) Lewis rats. FK506 (1 mg/kg; i.p.) or saline was administered systemically for 14 days after an endogenously healing tibia osteotomy was created and fixed with an intermedullary pin, and the overlying tibialis anterior (TA) muscle was either left uninjured or incurred volumetric muscle loss injury (6 mm full thickness biopsy from middle third of the muscle). RESULTS: The salient observations of this study were that 1) concomitant TA muscle trauma impaired recovery of tibia mechanical properties 28 days post-injury, 2) FK506 administration rescued the recovery of tibia mechanical properties in the presence of concomitant TA muscle trauma but did not augment mechanical recovery of an isolated osteotomy (no muscle trauma), 3) T lymphocytes and macrophage presence within the traumatized musculature were heightened by trauma and attenuated by FK506 3 days post-injury, and 4) T lymphocyte but not macrophage presence within the fracture callus were attenuated by FK506 at 14 days post-injury. FK506 did not improve TA muscle isometric torque production CONCLUSION: Collectively, these findings support the administration of FK506 to ameliorate healing of fractures with severe muscle trauma comorbidity. The results suggest one potential mechanism of action is a reduction in local T lymphocytes within the injured musculoskeletal tissue, though other mechanisms to include direct osteogenic effects of FK506 require further investigation

Novel adjuvant and vaccine delivery system for enhancement of protective immunity to coccidioidomycosis. (A) An agonist of human complement fragment C5a (EP67) bound to live cells of an attenuated vaccine strain of <i>Coccidioides</i> enhances T-cell immunity while downregulating inflammatory pathology.

<p>Hydration and dilation of live arthroconidia of the vaccine strain results in fracture of the hydrophobic outer conidial wall and exposure of lysine residues of the underlying inner wall that can conjugate with EP67 via S4BHyNic linkers (succinimidyl-4-benzoylhydrazino-nicotinamide). The concept is that the engineered conformational features of EP67 direct the conjugated vaccine to C5aR/CD88 receptors on DC and MΦ, but not neutrophils, and activate phagocytosis, antigen processing, and presentation by APCs while dampening persistent neutrophil-associated inflammation at infection sites <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Hung2" target="_blank">[12]</a>, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Morgan1" target="_blank">[13]</a>. <b>(B) A glucan particle (GP)-based subunit vaccine platform combines adjuvanicity with antigen delivery to induce robust and durable CD4⁺ and CD8⁺ T-cell responses to </b><b><i>Coccidioides</i></b><b> infection.</b> GPs are composed of a porous shell and hollow core. The protein vaccine is co-loaded with a carrier protein and interacted with yeast RNA within the core to form an antigen complex that is too large to diffuse out through the shell. Endo-Porter (EnP) peptides added to the antigen matrix enhance release of the CD8⁺ vaccine proteins to the cytoplasm of APCs after phagocytosis of GPs and promote processing and presentation of MHC I complexes, resulting in activation of protective CD8⁺ T cells. Between the antigen matrix and shell is a GP layer that can accommodate immune modulators (e.g., CpG, siRNA) that help to elicit a protective response to infection. Multiepitope constructs also may be coupled to the surface of GPs by addition of a pyridyl-S-cysteine peptide at the N-terminus (NPyr-Cys) of the vaccine protein. The C-terminus of GP surface-coupled vaccine proteins may be conjugated with EP67 as in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat-1003768-g001" target="_blank">Figure 1A</a>. EP67 directs the EBV to complement receptors and, although not yet tested, may further enhance Th17 immunity. CD4⁺ and CD8⁺ multiepitope vaccines are constructed using nonimmunogenic GPGPG or di-lysine (KK) linkers <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Livingston1" target="_blank">[25]</a>, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Yano1" target="_blank">[26]</a>. β-1,3-glucans and opsonic C3 deposited on the surface of GPs bind to Dectin-1 and complement receptors (CR), respectively, and induce phagocytosis by APCs (MΦ and DC) followed by antigen processing and peptide epitope display as MHC I or II complexes <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Hurtgen1" target="_blank">[17]</a>, <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003768#ppat.1003768-Huang1" target="_blank">[19]</a>.</p