Neutrophils; Proteases; Serpins; Apoptosis; Inflammation; Lung
Cremona T.P., Tschanz S.A., von Garnier C., Benarafa C. (2013), SerpinB1 deficiency is not associated with increased susceptibility to pulmonary emphysema in mice, in American Journal of Physiology - Lung Cellular and Molecular Physiology
, 305(12), L981-L989.
Baumann M., Pham C.T., Benarafa C. (2013), SerpinB1 is critical for neutrophil survival through cell-autonomous inhibition of cathepsin G, in Blood
, 121(19), 3900-3907.
Stolley J Michael, Gong Dapeng, Farley Kalamo, Zhao Picheng, Cooley Jessica, Crouch Erika C, Benarafa Charaf, Remold-O'Donnell Eileen (2012), Increased surfactant protein D fails to improve bacterial clearance and inflammation in serpinB1-/- mice., in American journal of respiratory cell and molecular biology
, 47(6), 792-9.
Gong Dapeng, Farley Kalamo, White Mitchell, Hartshorn Kevan L, Benarafa Charaf, Remold-O'Donnell Eileen (2011), Critical role of serpinB1 in regulating inflammatory responses in pulmonary influenza infection., in The Journal of infectious diseases
, 204(4), 592-600.
Fischer Heinz, Scherz Jennifer, Szabo Sandra, Mildner Michael, Benarafa Charaf, Torriglia Alicia, Tschachler Erwin, Eckhart Leopold (2011), DNase 2 is the main DNA-degrading enzyme of the stratum corneum., in PloS one
, 6(3), 1-9.
Benarafa Charaf, LeCuyer Tessa E, Baumann Mathias, Stolley James Michael, Cremona Tiziana P, Remold-O'Donnell Eileen (2011), SerpinB1 protects the mature neutrophil reserve in the bone marrow., in Journal of leukocyte biology
, 90(1), 21-29.
Benarafa Charaf (2011), The SerpinB1 knockout mouse a model for studying neutrophil protease regulation in homeostasis and inflammation., in Methods in enzymology
, 499, 135-148.
SerpinB1 is a member of the serpin (SERine Protease INhibitor) family of proteins, which function as irreversible inhibitors of serine proteases. SerpinB1, also known as MNEI (monocyte neutrophil elastase inhibitor), is arguably one of the best inhibitors of the three neutrophil serine proteases (NSPs), including neutrophil elastase, cathepsin G and proteinase-3. NSPs are key components of the innate defenses by directly killing invading microbes, a process that is largely occuring inside phagosomes. However, as a double edged sword, NSPs can turn against the host if released in excess of inhibitors in the extracellular milieu at infection or inflammatory sites. Indeed, excess NSPs can digest extracellular matrix, destroy innate immune defense molecules and antibodies and induce the production of inflammatory mediators.To explore a physiological role for serpinB1 in controlling excess NSPs in infectious and inflammatory disease, we have generated mice deficient for serpinB1 (serpinB1-/-) by targeted mutagenesis. These mice failed to clear, and succumbed to, Pseudomonas aeruginosa lung infection. This innate immune defect was due in part to increased proteolysis of lung surfactant protein-D and to early death of lung recruited neutrophils. These findings were highly significant because (i) it demonstrated that serpinB1, a cytoplasmic inhibitor of NSPs carried at high levels in neutrophils, provides a physiological and vital shield against extracellular pathologic actions of NSPs, and (ii) it indicated that serpinB1 has an additional function in neutrophil homeostasis at inflammatory sites. Building on these findings, neutrophil development and homeostasis in the bone marrow of serpinB1-/- mice was investigated further and preliminary evidence strongly suggests that serpinB1 is required to preserve the size of the neutrophil reservoir bone marrow. In addition, preliminary data also indicate that serpinB1 has a role in protecting lung epithelial cells against excess neutrophil serine proteases.To test the hypothesis that serpinB1 provides a cytoprotective shield in neutrophils and lung epithelial cells, we will focus on the following specific aims. In specific aim 1, we will investigate the mode, pathways and timing of cell death of bone marrow neutrophils in serpinB1-/- and wild type mice in steady state granulopoiesis using in vitro culture of neutrophils and mixed bone marrow chimera. In specific aim 2A, we will test whether the size of the bone marrow reservoir affects the kinetics of neutrophil recruitment, survival and function of neutrophils during acute lung injury. In specific aim2B, we will use a transgenic approach to test the hypothesis that intracellular levels of serpinB1 directly affect the size of the bone marrow neutrophil reservoir in steady state and the mobilization of neutrophils during inflammation. In aim 3, we will explore the regulation of serpinB1 expression in human lung epithelial cell lines and investigate a cytoprotective role for serpinB1 in primary culture of lung epithelial and mesenchymal cells of WT and serpinB1-/- mice.Overall, these studies will provide highly significant advances in understanding the regulation of neutrophil serine proteases in homeostasis of neutrophils and lung inflammation.