Research

Proteome of monocyte priming by lipopolysaccharide, including changes in interleukin-1beta and leukocyte elastase inhibitor

Michael J Pabst¹ , Karen M Pabst¹ , David B Handsman¹ , Sarka Beranova-Giorgianni^2,3 and Francesco Giorgianni³

¹  Dental Research Center and Department of Periodontology, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA

²  Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38163, USA

³  Department of Neurology, and the Charles B. Stout Mass Spectrometry Laboratory, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA

author email corresponding author email

Proteome Science 2008, 6:13doi:10.1186/1477-5956-6-13

Published:	20 May 2008

Abstract

Background

Monocytes can be primed in vitro by lipopolysaccharide (LPS) for release of cytokines, for enhanced killing of cancer cells, and for enhanced release of microbicidal oxygen radicals like superoxide and peroxide. We investigated the proteins involved in regulating priming, using 2D gel proteomics.

Results

Monocytes from 4 normal donors were cultured for 16 h in chemically defined medium in Teflon bags ± LPS and ± 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), a serine protease inhibitor. LPS-primed monocytes released inflammatory cytokines, and produced increased amounts of superoxide. AEBSF blocked priming for enhanced superoxide, but did not affect cytokine release, showing that AEBSF was not toxic. After staining large-format 2D gels with Sypro ruby, we compared the monocyte proteome under the four conditions for each donor. We found 30 protein spots that differed significantly in response to LPS or AEBSF, and these proteins were identified by ion trap mass spectrometry.

Conclusion

We identified 19 separate proteins that changed in response to LPS or AEBSF, including ATP synthase, coagulation factor XIII, ferritin, coronin, HN ribonuclear proteins, integrin alpha IIb, pyruvate kinase, ras suppressor protein, superoxide dismutase, transketolase, tropomyosin, vimentin, and others. Interestingly, in response to LPS, precursor proteins for interleukin-1β appeared; and in response to AEBSF, there was an increase in elastase inhibitor. The increase in elastase inhibitor provides support for our hypothesis that priming requires an endogenous serine protease.