Respiratory impairment during Pneumocystis Pneumonia (PcP) is closely related to exuberant pulmonary inflammation in response to the organism. Anti-inflammatory corticosteroids (in addition to antibiotics) improves outcome during PcP, but are associated with further immune suppression and co-infection. Our recent studies demonstrate that Pneumocystis cell wall components including 2-glucans (PCBG) interact with alveolar macrophages and epithelial cells stimulating release of cytokines and chemokines that promote inflammatory cell recruitment in the lungs. We further demonstrated that host cell lactosylceramide mediates inflammatory activation in response to Pneumocystis and purified PCBG. Furthermore, glucosylceramide synthase (GCS) inhibitors, which reduce lactosylceramide, not only strongly suppress lung inflammation during PcP, but also strongly suppress the numbers of Pneumocystis organisms in treated mice. Our data further support that Pc itself possesses GCS synthetic molecules necessary for organism viability. Thus, GCS inhibitors represent a potential new class of anti-Pneumocystis agents with both beneficial immune modulating activity as well as direct suppressive effects on Pc. We currently hypothesize that Pneumocystis activates deleterious inflammatory signaling in epithelial cells and macrophages through lactosylceramide mediated MAPK signaling with subsequent cytokine/chemokine generation. We further postulate that glycosphingolipid synthesis in the organism itself occurs through a PCGCS-1 synthetase essential for Pneumocystis viability. These concepts will be addressed through three independent, interrelated, aims.
Aim 1 will evaluate the mechanisms by which Pneumocystis and PCBG activate MAPK signaling in macrophages and epithelial cells, resulting in release of inflammatory cytokines and chemokines.
In Aim 2, we will define the GCS synthetic machinery of Pneumocystis by characterizing GSC-1 synthetase, and its role in Pc viability. Finally, Aim 3 will evaluate specific GCS inhibitors as both prophylactic and therapeutic regimens for PcP, defining their impact on lung inflammation, gas exchange, and organism burdens. Better understanding the roles of lactosylceramide related signaling during PcP will better define mechanisms of lung injury during this infection. More over, this proposal also represents the potential to develop a new class of anti-pneumocystis agents with important effects both on the organism, as well as on organism-driven lung inflammation, during this important infection.

Public Health Relevance

. Pneumocystis pneumonia remains a major cause of illness and death in patients with impaired host defenses, and is therefore of significant relevance for public health particularly in patients with AIDS, malignancies, and following organ transplantation. Lung inflammation during Pneumocystis pneumonia strongly contributes to lung injury and death during this infection. The following studies encompass the development of a new means to suppress both lung inflammation as well as the Pneumocystis organisms themselves during pneumonia.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL062150-20
Application #
8288164
Study Section
Lung Cellular, Molecular, and Immunobiology Study Section (LCMI)
Program Officer
Peavy, Hannah H
Project Start
1993-07-10
Project End
2013-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
20
Fiscal Year
2012
Total Cost
$377,750
Indirect Cost
$127,750
Name
Mayo Clinic, Rochester
Department
Type
DUNS #
006471700
City
Rochester
State
MN
Country
United States
Zip Code
55905
Dahlin, Jayme L; Walters, Michael A (2014) The essential roles of chemistry in high-throughput screening triage. Future Med Chem 6:1265-90
Dahlin, Jayme L; Kottom, Theodore; Han, Junhong et al. (2014) Pneumocystis jirovecii Rtt109, a novel drug target for Pneumocystis pneumonia in immunosuppressed humans. Antimicrob Agents Chemother 58:3650-9
Kottom, Theodore J; Limper, Andrew H (2013) The Pneumocystis Ace2 transcription factor regulates cell wall-remodeling genes and organism virulence. J Biol Chem 288:23893-902
Martin-Garrido, Isabel; Carmona, Eva M; Specks, Ulrich et al. (2013) Pneumocystis pneumonia in patients treated with rituximab. Chest 144:258-65
Pupaibool, Jakrapun; Limper, Andrew H (2013) Other HIV-associated pneumonias. Clin Chest Med 34:243-54
Pupaibool, Jakrapun; Kottom, Theodore J; Bouchonville, Kelly et al. (2013) Characterization of the Pneumocystis carinii histone acetyltransferase chaperone proteins PcAsf1 and PcVps75. Infect Immun 81:2268-75
Villegas, Leah R; Kottom, Theodore J; Limper, Andrew H (2012) Chitinases in Pneumocystis carinii pneumonia. Med Microbiol Immunol 201:337-48
Carmona, Eva M; Kottom, Theodore J; Hebrink, Deanne M et al. (2012) Glycosphingolipids mediate pneumocystis cell wall ?-glucan activation of the IL-23/IL-17 axis in human dendritic cells. Am J Respir Cell Mol Biol 47:50-9
Carmona, Eva M; Limper, Andrew H (2011) Update on the diagnosis and treatment of Pneumocystis pneumonia. Ther Adv Respir Dis 5:41-59
Kottom, Theodore J; Han, Junhong; Zhang, Zhiguo et al. (2011) Pneumocystis carinii expresses an active Rtt109 histone acetyltransferase. Am J Respir Cell Mol Biol 44:768-76

Showing the most recent 10 out of 44 publications