Septic shock is a major public health problem in both adults and children, and consequently there is a need to develop novel targets and therapeutic strategies. Based on microarray-centered clinical studies and follow up animal-centered experiments, we have indentified matrix metallopeptidase-8 (MMP-8) as a candidate target in sepsis pathology. MMP-8 is best known as a neutrophil product that cleaves collagen type 1 during extra-cellular matrix turnover. However, it has now become evident that MMP-8 also modulates acute inflammation and may play a role in sepsis pathology. The overarching hypothesis of this proposal is that MMP-8 expression and activity play a major role in sepsis pathology. We are now proposing to test this hypothesis via four complementary Specific Aims.
In Specific Aim 1 we will test the hypothesis that inhibition of MMP-8 activity improves multiple endpoints relevant to sepsis pathology.
This Aim will use MMP-8 null animals and a pharmacologic inhibitor of MMP-8 activity.
In Specific Aim 2 we will test the hypothesis that developmental age influences the role of MMP-8 in sepsis.
This Aim will use a sepsis model adaptable to 1 week old mouse pups, and will also make use of MMP-8 null mice and a pharmacologic inhibitor of MMP-8 activity.
In Specific Aim 3 we will test the hypothesis that bone marrow-derived cells are the main source of MMP-8 gene regulation in sepsis. The in vivo experiments for this Aim will involve adoptive transfer of MMP-8 null bone marrow to wild-type mice, and vice versa. The in vitro experiments for this Aim will systematically elucidate the signaling mechanisms that lead to de novo MMP-8 gene expression in neutrophils and monocytes.
In Specific Aim 4 we will test the hypothesis that collagen type 1 degradation products are involved in the mechanism by which MMP-8 regulates inflammation. The in vitro experiments for this Aim will test the ability of conditioned media, derived from collagen type 1 coated tissue culture plates treated with activated MMP-8, to activate macrophages. The in vivo experiments for this Aim will measure the response to sepsis in mice having a mutation of collagen type 1, which renders it resistant to cleavage by MMP-8. The major deliverables of this proposal include the establishment of MMP-8 as a novel therapeutic target in sepsis, the elucidation of how development influences the role of MMP-8 in sepsis, the elucidation of the major cellular source of MMP-8 in sepsis, a comprehensive understanding of the signaling mechanisms involved in MMP-8 expression during inflammation, and the establishment of MMP-8-dependent collagen type 1 degradation products as danger associated molecular patterns for the innate immune system.
The deliverable of this program will be the elucidation of a major role for MMP-8 expression and activity in sepsis pathology. Public health will be positively impacted by providing the foundation for the development of a novel therapeutic strategy for clinical sepsis.
|Slinko, Siarhei; Piraino, Giovanna; Hake, Paul W et al. (2014) Combined zinc supplementation with proinsulin C-peptide treatment decreases the inflammatory response and mortality in murine polymicrobial sepsis. Shock 41:292-300|
|Wynn, James L; Wong, Hector R; Shanley, Thomas P et al. (2014) Time for a neonatal-specific consensus definition for sepsis. Pediatr Crit Care Med 15:523-8|
|Atkinson, Sarah J; Wong, Hector R (2014) Identifying critically ill patients who may benefit from adjunctive corticosteroids: not as easy as we thought. Pediatr Crit Care Med 15:769-71|
|Maslove, David M; Wong, Hector R (2014) Gene expression profiling in sepsis: timing, tissue, and translational considerations. Trends Mol Med 20:204-13|
|Wong, Hector R (2013) Genome-wide expression profiling in pediatric septic shock. Pediatr Res 73:564-9|
|Hanna, William; Wong, Hector R (2013) Pediatric sepsis: challenges and adjunctive therapies. Crit Care Clin 29:203-22|
|Samraj, Ravi S; Zingarelli, Basilia; Wong, Hector R (2013) Role of biomarkers in sepsis care. Shock 40:358-65|
|Wong, Hector R (2012) Genetics and genomics in pediatric septic shock. Crit Care Med 40:1618-26|
|Solan, Patrick D; Dunsmore, Katherine E; Denenberg, Alvin G et al. (2012) A novel role for matrix metalloproteinase-8 in sepsis. Crit Care Med 40:379-87|