TGF-b2 induction regulates invasiveness of Theileria-transformed leukocytes and disease susceptibility.
Theileria parasites invade and transform bovine leukocytes causing either East Coast fever (T. parva), or tropical theileriosis (T. annulata). Susceptible animals usually die within weeks of infection, but indigenous infected cattle show markedly reduced pathology, suggesting that host genetic factors may cause disease susceptibility. Attenuated live vaccines are widely used to control tropical theileriosis and attenuation is associated with reduced invasiveness of infected macrophages in vitro. Disease pathogenesis is therefore linked to aggressive invasiveness, rather than uncontrolled proliferation of Theileria-infected leukocytes. We show that the invasive potential of Theileria-transformed leukocytes involves TGF-b signalling. Attenuated live vaccine lines express reduced TGF-b2 and their invasiveness can be rescued with exogenous TGF-b. Importantly, infected macrophages from disease susceptible Holstein-Friesian (HF) cows express more TGF-b2 and traverse Matrigel with great efficiency compared to those from disease-resistant Sahiwal cattle. Thus, TGF-b2 levels correlate with disease susceptibility. Using fluorescence and time-lapse video microscopy we show that Theileria-infected, disease-susceptible HF macrophages exhibit increased actin dynamics in their lamellipodia and podosomal adhesion structures and develop more membrane blebs. TGF-b2-associated invasiveness in HF macrophages has a transcription-independent element that relies on cytoskeleton remodelling via activation of Rho kinase (ROCK). We propose that a TGF-b autocrine loop confers an amoeboid-like motility on Theileria-infected leukocytes, which combines with MMP-dependent motility to drive invasiveness and virulence.
Institut Cochin, Université Paris-Descartes, Paris, France.
Marie
M
Chaussepied
Natacha
N
Janski
Martin
M
Baumgartner
Regina
R
Lizundia
Kirsty
K
Jensen
William
W
Weir
Brian R
BR
Shiels
Jonathan B
JB
Weitzman
Elizabeth J
EJ
Glass
Dirk
D
Werling
Gordon
G
Langsley
D000818:Animals; D017951:Antigen Presentation; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D003599:Cytoskeleton / Q000378:metabolism; D020869:Gene Expression Profiling; D006790:Host-Parasite Interactions; D007962:Leukocytes / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D016794:Theileria / Q000472:pathogenicity*; D013801:Theileriasis / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D014158:Transcription, Genetic; D053781:Transforming Growth Factor beta2 / Q000235:genetics / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D012333:RNA, Messenger; D053781:Transforming Growth Factor beta2; D054460:rho-Associated Kinases