Traditionally, the pulmonary surfactant protein-A (SP-A) is thought to opsonize and enhance the clearance of microbial pathogens. Recently, we have reported that SP-A also directly kills Pseudomonas aeruginosa (PA) in a macrophage-independent manner, by increasing the permeability of bacterial membranes. However, the mechanism by which SP-A disrupts PA cell membranes and its relative importance in lung defense are poorly defined. In addition, how microbes protect themselves against SP-A is unknown. Especially, we have shown that wild-type PA strain PA01 is resistant to membrane permeabilization by SP-A. Our long-term goal is to understand the antimicrobial mechanisms of SP-A, and to reveal how bacteria confer resistance/susceptibility to SP-A. The overall hypothesis to be tested is that PA pathways including flagellum, salicylate and pyochelin, and phosphoenol-pyruvate phosphotransferase, are important to resist membrane permeabilization by SP-A. Our hypothesis is supported by our published and preliminary data which show that PA mutant strains deficient in flagellum (flgE), deficient in salicylate and pyochelin biosynthesis (pchA), and defective in producing phosphoenol-pyruvate phosphotransferase (ptsP), are preferentially cleared in the SP-A+/+ mouse lungs, but survived in the SP-A-/- mouse lungs. Most strikingly, the flgE, pchA and ptsP mutant bacteria show significant increase in susceptibility to SP-A mediated membrane permeabilization, but not opsonization. We propose three aims to examine the mechanisms by which flagellum, PchA and PtsP pathways maintain LPS and cell membrane integrity, and regulate the bacterial processes that inactivate SP-A, to confer resistance to killing by SP-A-mediated membrane permeabilization and to killing by SP-A and antimicrobial peptides and proteins (AMPPs) whose functions that are either dependent or aided by SP-A.
Aim 1 will determine the """"""""offensive"""""""" strategies orchestrated by PA's flagellum, PchA and PtsP to confer resistance to SP-A-mediated membrane permeabilization. These offensive measures to be tested include the ability of PA to secrete proteases that degrade SP-A, and to secrete salicylate that strips Ca2+ associated with SP-A, which is required for the activity of SP-A.
Aim 2 will determine the """"""""defensive"""""""" strategies orchestrated by PA's flagellum, salicylate/pyochelin and phosphoenol-pyruvate phosphotransferase to confer resistance to SP-A-mediated membrane permeabilization. The defensive measures to be determined include increased LPS biosynthesis and modification, and chemotaxis evasion.
Aim 3 will examine the hypothesis that during the initial interactions, SP-A preemptively """"""""paralyzes"""""""" PA, allowing other AMPPs to act synergistically or additively to kill the bacteria. We will use """"""""checker board"""""""" assays to determine the roles of flagellum, PchA and PtsP pathways against individual, synergistic and additive killing by individual AMPP alone, different combinations of AMMPs, and AMMPs with SP-A. Completion of the proposed aims will enhance our understanding of the antimicrobial mechanisms of the SP-A and lead to new treatment strategies for pneumonias.

Public Health Relevance

Pseudomonas aeruginosa is one of the most common causes of nosocomial infections in humans, lung infections in cystic fibrosis patients, and a primary cause of death and sepsis in immuno-compromised individuals. The continuous emergence of antibiotic resistant P. aeruginosa, which can lead to denial for lung transplant, infection and death, emphasize the urgent need to explore alternative strategies to manage P. aeruginosa infections. Enhance understanding of the antimicrobial mechanisms of the Surfactant Protein A, and the mechanisms by which P. aeruginosa confers resistance/susceptibility to Surfactant Protein A may lead to new treatment strategies for life-threatening pneumonias.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL090699-04
Application #
8237000
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Eu, Jerry Pc
Project Start
2009-04-01
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2014-03-31
Support Year
4
Fiscal Year
2012
Total Cost
$386,019
Indirect Cost
$138,519
Name
University of Illinois Urbana-Champaign
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Lin, Jingjun; Zhu, Luchang; Lau, Gee W (2016) Disentangling competence for genetic transformation and virulence in Streptococcus pneumoniae. Curr Genet 62:97-103
Jeffries, Jayme L; Jia, Jing; Choi, Woosuk et al. (2016) Pseudomonas aeruginosa pyocyanin modulates mucin glycosylation with sialyl-Lewis(x) to increase binding to airway epithelial cells. Mucosal Immunol 9:1039-1050
Parkinson, Elizabeth I; Bair, Joseph S; Nakamura, Bradley A et al. (2015) Deoxynybomycins inhibit mutant DNA gyrase and rescue mice infected with fluoroquinolone-resistant bacteria. Nat Commun 6:6947
Jin, Zhigang; Chung, Jin Wei; Mei, Wenyan et al. (2015) Regulation of nuclear-cytoplasmic shuttling and function of Family with sequence similarity 13, member A (Fam13a), by B56-containing PP2As and Akt. Mol Biol Cell 26:1160-73
Tan, Rommel M; Kuang, Zhizhou; Hao, Yonghua et al. (2015) Type IV pilus glycosylation mediates resistance of Pseudomonas aeruginosa to opsonic activities of the pulmonary surfactant protein A. Infect Immun 83:1339-46
Zhu, Luchang; Lin, Jingjun; Kuang, Zhizhou et al. (2015) Deletion analysis of Streptococcus pneumoniae late competence genes distinguishes virulence determinants that are dependent or independent of competence induction. Mol Microbiol 97:151-65
Tan, Rommel Max; Kuang, Zhizhou; Hao, Yonghua et al. (2014) Type IV pilus of Pseudomonas aeruginosa confers resistance to antimicrobial activities of the pulmonary surfactant protein-A. J Innate Immun 6:227-39
Hao, Yonghua; Kuang, Zhizhou; Jing, Jia et al. (2014) Mycoplasma pneumoniae modulates STAT3-STAT6/EGFR-FOXA2 signaling to induce overexpression of airway mucins. Infect Immun 82:5246-55
Xu, Ying; Duan, Chaohui; Kuang, Zhizhou et al. (2013) Pseudomonas aeruginosa pyocyanin activates NRF2-ARE-mediated transcriptional response via the ROS-EGFR-PI3K-AKT/MEK-ERK MAP kinase signaling in pulmonary epithelial cells. PLoS One 8:e72528
Hao, Yonghua; Kuang, Zhizhou; Xu, Ying et al. (2013) Pyocyanin-induced mucin production is associated with redox modification of FOXA2. Respir Res 14:82

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