Conjugation of alginate to a synthetic peptide containing T- and B-cell epitopes as an induction for protective immunity against Pseudomonas aeruginosa

Recent Advances in Degradable Biomedical Polymers for Prevention, Diagnosis and Treatment of Diseases

Biomedical polymers play a key role in preventing, diagnosing, and treating diseases, showcasing a wide range of applications. Their unique advantages, such as rich source, good biocompatibility, and excellent modifiability, make them ideal biomaterials for drug delivery, biomedical imaging, and tissue engineering. However, conventional biomedical polymers suffer from poor degradation in vivo, increasing the risks of bioaccumulation and potential toxicity. To address these issues, degradable biomedical polymers can serve as an alternative strategy in biomedicine. Degradable biomedical polymers can efficiently relieve bioaccumulation in vivo and effectively reduce patient burden in disease management. This review comprehensively introduces the classification and properties of biomedical polymers and the recent research progress of degradable biomedical polymers in various diseases. Through an in-depth analysis of their classification, properties, and applications, we aim to provide strong guidance for promoting basic research and clinical translation of degradable biomedical polymers.

Modification of Alginates to Modulate Their Physic-Chemical Properties and Obtain Biomaterials with Different Functional Properties

Modified alginates have a wide range of applications, including in the manufacture of dressings and scaffolds used for regenerative medicine, in systems for selective drug delivery, and as hydrogel materials. This literature review discusses the methods used to modify alginates and obtain materials with new or improved functional properties. It discusses the diverse biological and functional activity of alginates. It presents methods of modification that utilize both natural and synthetic peptides, and describes their influence on the biological properties of the alginates. The success of functionalization depends on the reaction conditions being sufficient to guarantee the desired transformations and provide modified alginates with new desirable properties, but mild enough to prevent degradation of the alginates. This review is a literature description of efficient methods of alginate functionalization using biologically active ligands. Particular attention was paid to methods of alginate functionalization with peptides, because the combination of the properties of alginates and peptides leads to the obtaining of conjugates with properties resulting from both components as well as a completely new, different functionality.

Vaccines for multidrug resistant Gram negative bacteria: lessons from the past for guiding future success

Antimicrobial resistance is a major threat to global public health. Vaccination is an effective approach for preventing bacterial infections, however it has not been successfully applied to infections caused by some of the most problematic multidrug resistant pathogens. In this review, the potential for vaccines to contribute to reducing the burden of disease of infections caused by multidrug resistant Gram negative bacteria is presented. Technical, logistical and societal hurdles that have limited successful vaccine development for these infections in the past are identified, and recent advances that can contribute to overcoming these challenges are assessed. A synthesis of vaccine technologies that have been employed in the development of vaccines for key multidrug resistant Gram negative bacteria is included, and emerging technologies that may contribute to future successes are discussed. Finally, a comprehensive review of vaccine development efforts over the last 40 years for three of the most worrisome multidrug resistant Gram negative pathogens, Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa is presented, with a focus on recent and ongoing studies. Finally, future directions for the vaccine development field are highlighted.

Understanding Pseudomonas aeruginosa-Host Interactions: The Ongoing Quest for an Efficacious Vaccine

Pseudomonas aeruginosa is a leading cause of chronic respiratory infections in people with cystic fibrosis (CF), bronchiectasis or chronic obstructive pulmonary disease (COPD), and acute infections in immunocompromised individuals. The adaptability of this opportunistic pathogen has hampered the development of antimicrobial therapies, and consequently, it remains a major threat to public health. Due to its antimicrobial resistance, vaccines represent an alternative strategy to tackle the pathogen, yet despite over 50 years of research on anti-Pseudomonas vaccines, no vaccine has been licensed. Nevertheless, there have been many advances in this field, including a better understanding of the host immune response and the biology of P. aeruginosa. Multiple antigens and adjuvants have been investigated with varying results. Although the most effective protective response remains to be established, it is clear that a polarised Th2 response is sub-optimal, and a mixed Th1/Th2 or Th1/Th17 response appears beneficial. This comprehensive review collates the current understanding of the complexities of P. aeruginosa-host interactions and its implication in vaccine design, with a view to understanding the current state of Pseudomonal vaccine development and the direction of future efforts. It highlights the importance of the incorporation of appropriate adjuvants to the protective antigen to yield optimal protection.

Comparative study of the immune responses to the HMS-based fusion protein and capsule-based conjugated molecules as vaccine candidates in a mouse model of Staphylococcus aureus systemic infection

Staphylococcus aureus is a powerful pathogen that causes a wide range of infectious diseases and results in a high mortality rate in humans. Treating S. aureus-related infections is extremely difficult because of its ability to resist many antibiotics; therefore, developing an effective vaccine against this infection can be an alternative and promising approach. In this study, we evaluated the protective effects of a Hla-MntC-SACOL0723 multi-epitope protein (HMS) compared with HMS conjugated to polysaccharides 5 and 8 (CP5 and CP8) of S. aureus and CP5 and CP8 in a mouse sepsis model. To evaluate the type of induced immune response, specific IgG, and antibody isotypes (IgG1 and IgG2a) were determined using the ELISA method. The functional activity of these vaccine candidates was assessed by opsonophagocytosis. Mice were infected with S. aureus COL strain and evaluated for bacterial load in the kidney and spleen homogenates. Th1, Th2, and Th17-related cytokines in the spleen cell supernatants were assessed by flow cytometry. The therapeutic effect of specific anti-HMS protein IgG antibodies against S. aureus COL strain infection was evaluated by passive immunization. HMS recombinant protein induced a higher level of Th1, Th2, and Th17-related cytokines compared with conjugated molecules. Also, mice immunized with the HMS protein reduced the bacterial load in the kidney and spleen more than the one that received the conjugated molecules. Our study suggests that the HMS fusion protein and conjugate molecule vaccine candidates could be suitable candidates for the removal of S. aureus in the mouse sepsis model but HMS protein can be a more effective candidate.

Potential targets for next generation antimicrobial glycoconjugate vaccines

Cell surface carbohydrates have been proven optimal targets for vaccine development. Conjugation of polysaccharides to a carrier protein triggers a T-cell-dependent immune response to the glycan moiety. Licensed glycoconjugate vaccines are produced by chemical conjugation of capsular polysaccharides to prevent meningitis caused by meningococcus, pneumococcus and Haemophilus influenzae type b. However, other classes of carbohydrates (O-antigens, exopolysaccharides, wall/teichoic acids) represent attractive targets for developing vaccines. Recent analysis from WHO/CHO underpins alarming concern toward antibiotic-resistant bacteria, such as the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) and additional pathogens such as Clostridium difficile and Group A Streptococcus. Fungal infections are also becoming increasingly invasive for immunocompromised patients or hospitalized individuals. Other emergencies could derive from bacteria which spread during environmental calamities (Vibrio cholerae) or with potential as bioterrorism weapons (Burkholderia pseudomallei and mallei, Francisella tularensis). Vaccination could aid reducing the use of broad-spectrum antibiotics and provide protection by herd immunity also to individuals who are not vaccinated.

This review analyzes structural and functional differences of the polysaccharides exposed on the surface of emerging pathogenic bacteria, combined with medical need and technological feasibility of corresponding glycoconjugate vaccines.