Abstract
Kinin B1 receptors (B1R) are involved in many pathophysiological processes, and its expression is up-regulated in inflammatory pulmonary disease. Although bacteria can generate kinin peptides, the molecular signaling mechanisms regulating B1R during infection by intact pathogens is unknown. The serious opportunistic clinical isolate Burkholderia cenocepacia (B. cen.) belongs to the important B. cepacia complex (Bcc) of gram-negative pathogens that rapidly causes fatal pulmonary disease in hospitalized and immunocompromised patients and those with cystic fibrosis. We demonstrate here that B. cen. infection induced a rapid increase in B1R mRNA (1 h) proceeded by an increase in B1R protein expression (2 h), without affecting B2 receptor expression in human pulmonary fibroblasts. The B1R response was dose-dependent and maximal by 6 to 8 h (3- to 4-fold increase), however, brief B. cen. infection could sustain B1R up-regulation. In contrast, nonclinical Bcc phytopathogens were much less B1R inducive. The protein synthesis inhibitor cycloheximide and transcriptional inhibitor actinomycin D abrogated the B1 response to B. cen. indicating de novo B1R synthesis. B. cen. activated p38 mitogen-activated protein kinase (MAPK), and blocking p38 MAPK with the specific inhibitor 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580) dramatically reduced B. cen.-induced B1R. Furthermore, B. cen. regulation of B1R was diminished by the anti-inflammatory glucocorticoid dexamethasone. In conclusion, this study is the first demonstration that infection with intact pulmonary pathogens like B. cen. positively modulates the selective expression of B1R. Thus, providing evidence that B1R regulation may be an important and novel mechanism in the inflammatory cascade in response to chronic pulmonary infection and disease.
Footnotes
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This work was supported by a grant from the Cystic Fibrosis Foundation, American Lung Association of California, Webb Foundation, Fellowship from the Saban Research Institute of Childrens Hospital Los Angeles, National Institutes of Health Grant HL60231, Swedish Research Council, and Medical Faculty of Lund University.
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This work was presented in part at the 17th Annual North American Cystic Fibrosis Conference, Anaheim, CA, Oct 16–19, 2003. Pediatr PulmonolSuppl 25:277.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.104.083030.
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ABBREVIATIONS: BK, bradykinin; CF, cystic fibrosis; KD, kallidin; Bcc, Burkholderia cepacia complex; MAPK, mitogen-activated protein kinase; DMEM, Dulbecco's modified Eagle's medium; IL, interleukin; MOI, multiplicity of infection; PCR, polymerase chain reaction; bp, base pair(s); SB 203580, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; ERK, extracellular signal-regulated kinase; JNK, c-Jun N-terminal kinase; PD 98059, 2′-amino-3′methoxyflavone; SP600125, anthra[1,9-cd]pyrazole-6 (2H)-one.
- Received December 30, 2004.
- Accepted February 28, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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