Vaccines and antibodies in the prevention and treatment of sepsis

Divergent Sepsis Pathophysiology in Older Adults

Significance: Both incidence and mortality rates of sepsis significantly increase with advanced age, and the majority of sepsis patients are late middle-aged or older. With the proportion of older adults rapidly increasing in developed countries, age-dependent sepsis vulnerability is an urgent medical issue. Due to an increasing life expectancy, postsepsis complications and health care costs are expected to increase as well. Recent Advances: Older patients suffer from higher sepsis incidence and mortality rates, likely resulting from frequent comorbidities, increased coagulation, dysgylcemia, and altered immune responses. Critical Issues: Despite a large number of ongoing clinical and basic research studies, there is currently no effective therapeutic strategy targeting older patients with severe sepsis. The disparity between clinical and basic studies is a problem, and this is largely due to the use of animal models lacking clinical relevance. Although the majority of sepsis cases occur in older adults, most laboratory animals used for sepsis research are very young. Further, despite the wide use of combination fluid and antibiotic treatment in intensive care unit (ICU) patients, most animal research does not include such treatment. Future Directions: Because sepsis is a systemic disease with multiple organ dysfunction, combined therapy approaches, not those targeting single pathways or single organs, are essential. As for preclinical research, it is critical to confirm new findings using aged animal models with clinically relevant ICU-like medical treatments. Antioxid. Redox Signal. 35, 1358-1375.

Development of an anti-endotoxin vaccine for sepsis

Gram-negative bacterial lipopolysaccharide (LPS, endotoxin) is an important initiator of sepsis, a clinical syndrome that is a leading cause of death in intensive care units. Vaccines directed against core LPS structures that are widely conserved among Gram-negative bacteria (GNB) have been developed for the treatment and/or prevention of sepsis. Killed whole bacterial vaccines (E. coli O111:B4, J5 [Rc chemotype] mutant and S. minnesota, Re chemotype) protected mice against experimental sepsis. Human J5 immune antisera reduced the mortality from GNB sepsis in a large controlled clinical trial; however, subsequent clinical studies with antiendotoxin antibodies did not demonstrate protective efficacy in sepsis. Multiple clinical studies have since demonstrated a correlation between the level of circulating antibodies to LPS core and morbidity and mortality in different clinical settings. We therefore developed a subunit vaccine by combining detoxified J5 LPS (J5 dLPS) with the outer membrane protein (OMP) from group B N. meningitidis. This vaccine was highly efficacious in experimental models of sepsis and progressed to phase 1 clinical trial. While well-tolerated, this vaccine induced only 3-4-fold increases in anti-J5 dLPS antibody. Addition of the TLR9 agonist, oligodeoxynucleotide with a CpG motif, as adjuvant to the vaccine increased antibody levels in mice and the vaccine/CpG combination will progress to phase 1 human study. Additional vaccines in which the core glycolipid was either conjugated to carrier protein or incorporated into liposomes have been developed, but have not progressed to clinical trial. Should an antiendotoxin vaccine become available, a new immunization strategy directed towards distinct populations at risk will be required.