Innate immune responses to LPS in mouse lung are suppressed and reversed by neutralization of GM-CSF via repression of TLR-4

Abstract

The innate immune inflammatory response to lipopolysaccharide (LPS, an endotoxin) is essential for lung host defense against infection by gram-negative bacteria but is also implicated in the pathogenesis of some lung diseases. Studies on genetically altered mice implicate granulocyte-macrophage colony-stimulating factor (GM-CSF) in lung responses to LPS; however, the physiological effects of GM-CSF neutralization are poorly characterized. We performed detailed kinetic and dose-response analyses of the lung inflammation response to LPS in the presence of the specific GM-CSF-neutralizing antibody 22E9. LPS instilled into the lungs of BALB/c mice induced a dose-dependent inflammation comprised of intense neutrophilia, macrophage infiltration and proliferation, TNF-alpha and matrix metalloproteinase release, and macrophage inflammatory protein-2 induction. The neutralization of anti-GM-CSF in a dose-dependent fashion suppressed these inflammatory indexes by 85% when given before or after LPS or after repeat LPS challenges. Here we report for the first time that the physiological expression of Toll-like receptor-4 in lung is reduced by anti-GM-CSF. We observed that lower Toll-like receptor-4 expression correlated with a similar decline in peak TNF- levels in response to endotoxin. Consequently, sustained expression of key inflammatory mediators over 24 h was reduced. These data expand the understanding of the contribution of GM-CSF to innate immune responses in lung and suggest that blocking GM-CSF might benefit some lung diseases where LPS has been implicated in etiology.

Granulocyte–macrophage colony stimulating factor-mediated innate responses in tuberculosis

“…These findings are consistent with previous findings showing an important role of GM-CSF in granuloma formation 24,40 and the importance of GM-CSF on secretion of macrophage TNFα. 10,23,36,48,49 TNFα is a critical mediator of granuloma formation in tuberculosis. 24,50,51 However, our findings in GMKO mice indicate that protection of the distal lung epithelial cells must be secured early in the course of the infection even before granuloma formation and immunological containment of virulent mycobacteria can take place locally.…”

N,N-Dimethylacetamide Significantly Attenuates LPS- and TNFα-Induced Proinflammatory Responses Via Inhibition of the Nuclear Factor Kappa B Pathway

“…Further investigation is warranted to answer this important question. Significantly, inhibition of IκBα and IKKs has been Further, Bozinovski et al showed that LPS-induced lung inflammation is ameliorated by neutralizing GM-CSF (69). Finally, elevated levels of GM-CSF, in addition to IL-6 and IL-8, were recently found in amniotic fluid in the setting of infection (70).…”

Effect of Short-Term Cigarette Smoke Exposure on Body Weight, Appetite and Brain Neuropeptide Y in Mice

“…The purified total RNA rep was used as a template to generate first-strand cDNA synthesis using Super Script II (Invitrogen) as described previously (Bozinovski et al, 2004). The reaction mix containing 1 mg of RNA, 250 ng of random hexamers (Promega), and 10 mM dNTP mix was diluted to 12 ml in sterile water, heated to 651C for 5 min and chilled on ice for 1 min.…”

“…cDNA was diluted 10-fold in sterile water and stored at À201C prior to amplification. Quantitative real-time PCR was performed as described previously (ABI PRISM 7900 HT Sequence Detection System) (Bozinovski et al, 2004) using predeveloped primers from Applied Biosystem. Briefly, gene expression was quantified by multiplexing single reaction, where our gene of interest (UCP1, UCP3, and TNF a) was standardized to control (18 s rRNA).…”