Immunomodulatory and Antibacterial Effects of Cystatin 9 against Francisella tularensis
Cystatin 9 (CST9) is a member of the type 2 cysteine protease inhibitor family, which has been shown to have immunomodulatory effects that restrain inflammation, but its functions against bacterial infections are unknown. Here, we report that purified human recombinant (r)CST9 protects against the deadly bacterium Francisella tularensis (Ft) in vitro and in vivo. Macrophages infected with the Ft human pathogen Schu 4 (S4), then given 50 pg of rCST9 exhibited significantly decreased intracellular bacterial replication and increased killing via preventing the escape of S4 from the phagosome. Further, rCST9 induced autophagy in macrophages via the regulation of the mammalian target of rapamycin (mTOR) signaling pathways. rCST9 promoted the upregulation of macrophage proteins involved in antiinflammation and antiapoptosis, while restraining proinflammatory-associated proteins. Interestingly, the viability and virulence of S4 also was decreased directly by rCST9. In a mouse model of Ft inhalation, rCST9 significantly decreased organ bacterial burden and improved survival, which was not accompanied by excessive cytokine secretion or subsequent immune cell migration. The current report is the first to show the immunomodulatory and antimicrobial functions of rCST9 against Ft. We hypothesize that the attenuation of inflammation by rCST9 may be exploited for therapeutic purposes during infection.
This work was supported by Eaves-Pyles’ NIH/NIAID (R21-A106877402). We would like to thank Istvan Boldogh (Department of Microbiology and Immunology, University of Texas Medical Branch) for his advice, suggestions and input on the in vivo studies presented herein and Bill Calhoun (Department of Internal Med-Pulmonary, University of Texas Medical Branch) for his contribution to the autophagy results. We are gratefuly to the Biomolecule Analysis Core Facility at the BBRC/Biology/UTEP (NIH grants G12M0007592, 5G12RR008124-16A1 and 5G12RR008124-16A1S1) for proteomic analysis.
- 3.Zavasnik-Bergant T. (2008) Cystatin protease inhibitors and immune functions. Front. Biosci. 4625–37.Google Scholar
- 11.Gauthier S, Kaur G, Mi W, Tizon B, Levy E. (2011) Protective mechanisms by cystatin C in neurodegenerative diseases. Front. Biosci. 3:541–54.Google Scholar
- 16.Jacobs RF. (1977) Tularemia. Ad. Ped. Infect. Dis. 12:55–69.Google Scholar
- 17.Sjöstedt A, Tärnvik A, Sandström G. (1996) Francisella tuarensis Host-parasite interaction. FEMS Immun. Med. Micro. 13:181–4.Google Scholar
- 33.Chung S, Sundar IK, Yao H, Ho YS, Rahman I. (2010) Glutaredoxin 1 regulates cigarette smokemediated lung inflammation through differential modulation of IkappaB kinases in mice: impact on histone acetylation. Am. J. Physiol. Lung Cell Mol. Physiol. 299:L192–203.CrossRefPubMedPubMedCentralGoogle Scholar
- 34.Mor-Vaknin N, et al. (2011) Vimentin suppresses the production of reactive oxygen species and the antimicrobial response via p47phox [abstract]. Arthritis Rheum. 63 Suppl 10:1003.Google Scholar
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, and provide a link to the Creative Commons license. You do not have permission under this license to share adapted material derived from this article or parts of it.
The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this license, visit (https://doi.org/creativecommons.org/licenses/by-nc-nd/4.0/)