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.
Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555, USA. tdeavesp@utmb.edu
Tonyia
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Eaves-Pyles
Jignesh
J
Patel
Emma
E
Arigi
Yingzi
Y
Cong
Anthony
A
Cao
Nisha
N
Garg
Monisha
M
Dhiman
Richard B
RB
Pyles
Bernard
B
Arulanandam
Aaron L
AL
Miller
Vsevolod L
VL
Popov
Lynn
L
Soong
Eric D
ED
Carlsen
Ciro
C
Coletta
Csaba
C
Szabo
Igor C
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Almeida
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002465:Cell Movement / Q000187:drug effects; D015891:Cystatins / Q000235:genetics / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D005604:Francisella tularensis / Q000187:drug effects* / Q000472:pathogenicity; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology* / Q000627:therapeutic use; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis / Q000187:drug effects; D011994:Recombinant Proteins / Q000494:pharmacology* / Q000627:therapeutic use; D014406:Tularemia / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D014774:Virulence / Q000187:drug effects
D000900:Anti-Bacterial Agents; C472711:CST9 protein, human; D015891:Cystatins; D007155:Immunologic Factors; D011994:Recombinant Proteins