Faculty Bibliography

OBJECTIVES: Particulate matter (PM) exposure causes adverse health effects. The WTC collapse led to significant PM exposure and lung injury (Weiden et al. Chest 2009). The mechanism by which WTC PM causes pulmonary morbidity is not understood. We are investigating the differential cytokine effects on human alveolar cells, comparing ambient PM of WTC to ambient PM from NYC, South Bronx (SB) and Sterling Forest (SF), a rural area northwest of NYC. METHODS AND POPULATION: AM were obtained from Bronchoalveolar lavage (BAL) by adherence overnight. AM were exposed to 50mug/mL suspensions of WTC, SB, and SF PM2.5. Media alone was the negative control and 40 ng/mL of LPS was the positive control. After 24hrs, supernatants were collected and analyzed in duplicate using Human Cytokine Panel I (Millipore) on a Luminex-200. RESULTS: Fold induction of mediators was expressed as ratios of PM exposure/media alone. Exposure to WTC PM was markedly more inflammatory than SB and SF. The most significant inductions were of the leukocyte growth factors (GM-CSF, G-CSF), a promoter of angiogenesis (VEGF), the chemokine (RANTES) and the potent multifunctional cytokine IL-6. LPS caused a greater induction for all of the analytes when compared to WTC PM except for IL-1ra. SIGNIFICANCE OF STUDY: WTC PM2.5 produces a marked inflammatory effect in comparison to PM2.5 from both NYC, SB and rural sites. The large number of cytokines induced by WTC PM may drive airway injury and may be biomarkers for lung injury. WTC PM has been observed in induced sputum obtained 9 months after 9/11/2001 and so the elaboration of cytokines may underlie the severe and long lasting health effects produced by exposure to WTC PM

BACKGROUND: Inflammation in the early stages of sepsis is governed by the innate immune response. Costimulatory molecules are a receptor/ligand class of molecules capable of regulation of inflammation in innate immunity via macrophage/neutrophil contact. We recently described that CD80/86 ligation is required for maximal macrophage activation and CD80/86(-/-) mice display reduced mortality and inflammatory cytokine production after cecal ligation and puncture (CLP). However, these data also demonstrate differential regulation of CD80 and CD86 expression in sepsis, suggesting a divergent role for these receptors. Therefore, the goal of this study was to determine the individual contribution of CD80/86 family members in regulating inflammation in sepsis. METHODOLOGY/PRINCIPAL FINDINGS: CD80(-/-) mice had improved survival after CLP when compared to WT or CD86(-/-) mice. This was associated with preferential attenuation of inflammatory cytokine production in CD80(-/-) mice. Results were confirmed with pharmacologic blockade, with anti-CD80 mAb rescuing mice when administered before or after CLP. In vitro, activation of macrophages with neutrophil lipid rafts caused selective disassociation of IRAK-M, a negative regulator of NF-kappaB signaling from CD80; providing a mechanism for preferential regulation of cytokine production by CD80. Finally, in humans, upregulation of CD80 and loss of constitutive CD86 expression on monocytes was associated with higher severity of illness and inflammation confirming the findings in our mouse model. CONCLUSIONS: In conclusion, our data describe a differential role for CD80 and CD86 in regulation of inflammation in the innate immune response to sepsis. Future therapeutic strategies for blockade of the CD80/86 system in sepsis should focus on direct inhibition of CD80