TY - JOUR
T1 - Extracellular matrix lumican promotes bacterial phagocytosis, and Lum -/- mice show increased Pseudomonas aeruginosa lung infection severity
AU - Shao, Han Juan
AU - Lee, Seakwoo
AU - Gae-Scott, Sherri
AU - Nakata, Chiaki
AU - Chen, Shoujun
AU - Hamad, Abdel R.
AU - Chakravarti, Shukti
PY - 2012/10/19
Y1 - 2012/10/19
N2 - Phagocytosis is central to bacterial clearance, but the exact mechanism is incompletely understood. Here, we show a novel and critical role for lumican, the connective tissue extracellular matrix small leucine-rich repeat proteoglycan, in CD14-mediated bacterial phagocytosis. In Psuedomonas aeruginosa lung infections, lumican-deficient (Lum-/-) mice failed to clear the bacterium from lungs, tissues, and showed a dramatic increase in mortality. In vitro, phagocytosis of nonopsonized Gram-negative Escherichia coli and P. aeruginosa was inhibited in Lum-/- peritoneal macrophages (MΦs). Lumican co-localized with CD14, CD18, and bacteria on Lum+/+ MΦ surfaces. Using two different P. aeruginosa strains that require host CD14 (808) or CD18/CR3 (P1) for phagocytosis, we showed that lumican has a larger role in CD14-mediated phagocytosis. Recombinant lumican (rLum) restored phagocytosis in Lum-/- MΦs. Surface plasmon resonance showed specific binding of rLum to CD14 (KA= 2.15 ×106M-1), whereas rLumY20A, and not rLumY21A, where a tyrosine in each was replaced with an alanine, showed 60-fold decreased binding. The rLumY20A variant also failed to restore phagocytosis in Lum-/- MΦs, indicating Tyr-20 to be functionally important. Thus, in addition to a structural role in connective tissues, lumican has a major protective role in Gram-negative bacterial infections, a novel function for small leucine-rich repeat proteoglycans.
AB - Phagocytosis is central to bacterial clearance, but the exact mechanism is incompletely understood. Here, we show a novel and critical role for lumican, the connective tissue extracellular matrix small leucine-rich repeat proteoglycan, in CD14-mediated bacterial phagocytosis. In Psuedomonas aeruginosa lung infections, lumican-deficient (Lum-/-) mice failed to clear the bacterium from lungs, tissues, and showed a dramatic increase in mortality. In vitro, phagocytosis of nonopsonized Gram-negative Escherichia coli and P. aeruginosa was inhibited in Lum-/- peritoneal macrophages (MΦs). Lumican co-localized with CD14, CD18, and bacteria on Lum+/+ MΦ surfaces. Using two different P. aeruginosa strains that require host CD14 (808) or CD18/CR3 (P1) for phagocytosis, we showed that lumican has a larger role in CD14-mediated phagocytosis. Recombinant lumican (rLum) restored phagocytosis in Lum-/- MΦs. Surface plasmon resonance showed specific binding of rLum to CD14 (KA= 2.15 ×106M-1), whereas rLumY20A, and not rLumY21A, where a tyrosine in each was replaced with an alanine, showed 60-fold decreased binding. The rLumY20A variant also failed to restore phagocytosis in Lum-/- MΦs, indicating Tyr-20 to be functionally important. Thus, in addition to a structural role in connective tissues, lumican has a major protective role in Gram-negative bacterial infections, a novel function for small leucine-rich repeat proteoglycans.
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U2 - 10.1074/jbc.M112.380550
DO - 10.1074/jbc.M112.380550
M3 - Article
C2 - 22865855
AN - SCOPUS:84867809497
SN - 0021-9258
VL - 287
SP - 35860
EP - 35872
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 43
ER -