Immune suppression increases the incidence of invasive fungal infections, particularly those caused by the opportunistic mold Aspergillus fumigatus. Previous investigations revealed that members of the Toll-like receptor (TLR) family are not absolutely required for host defense against A. fumigatus in non-immunosuppressed hosts, suggesting that other pattern recognition receptors (PRRs) are involved. We show here that naive mice (i.e. not pharmacologically immunosuppressed) lacking the beta-glucan receptor Dectin-1 (Dectin-1−/−) are more sensitive to intratracheal challenge with A. fumigatus than control mice, exhibiting >80% mortality within 5 days, ultimately attributed to a compromise in respiratory mechanics. In response to A. fumigatus challenge, Dectin-1−/− mice demonstrated impaired interleukin (IL)-α, IL-1β, tumor necrosis factor (TNF)-α, CCL3/macrophage inflammatory protein (MIP)-α, CCL4/MIP-1β and CXCL1/KC production, which resulted in insufficient lung neutrophil recruitment and uncontrolled A. fumigatus lung growth. Alveolar macrophages from Dectin-1−/− mice failed to produce proinflammatory mediators in response to A. fumigatus, whereas neutrophils from Dectin-1−/− mice had impaired reactive oxygen species production and impaired killing of A. fumigatus. We further show that IL-17 production in the lung after A. fumigatus challenge was Dectin-1 dependent and that neutralization of IL-17 significantly impaired A. fumigatus clearance. Collectively, these results support a requisite role for Dectin-1 in in vivo defense against A. fumigatus.

We have previously reported that compromised interleukin 17A (IL-17A) production in the lungs increased susceptibility to infection with the invasive fungal pathogenAspergillus fumigatus. Here we have shown that culturing lung cells fromA. fumigatus-challenged miceex vivodemonstrated Dectin-1-dependent IL-17A production. In this system, neutralization of IL-23 but not IL-6, IL-1β, or IL-18 resulted in attenuated IL-17A production.Il23mRNA expression was found to be lower in lung cells fromA. fumigatus-challenged Dectin-1-deficient mice, whereas bone marrow-derived dendritic cells from Dectin-1-deficient mice failed to produce IL-23 in response toA. fumigatusin vitro. Addition of recombinant IL-23 augmented IL-17A production by wild-type (WT) and Dectin-1-deficient lung cells, although the addition of IL-6 or IL-1β did not augment the effect of IL-23. Intracellular cytokine staining of lung cells revealed lower levels of CD11b+IL-17A+and Ly-6G+IL-17A+cells inA. fumigatus-challenged Dectin-1-deficient mice. Ly-6G+neutrophils purified from the lungs ofA. fumigatus-challenged Dectin-1-deficient mice displayed lowerIl17amRNA expression but surprisingly had intactRorcandRoramRNA expression. We further demonstrated that Ly-6G+neutrophils required the presence of myeloid cells for IL-17A production. Finally, uponin vitrostimulation withA. fumigatus, thioglycolate-elicited peritoneal neutrophils were positive for intracellular IL-17A expression and produced IL-17A in a Dectin-1- and IL-23-dependent manner. In summary, Dectin-1-dependent IL-17A production in the lungs during invasive fungal infection is mediated in part by CD11b+Ly-6G+neutrophils in an IL-23-dependent manner.

Two homologous apoA-I mimetic peptides, 3F-2 and 3F 14 , differ in their in vitro antiatherogenic properties (Epand, R. M., Epand, R. F., Sayer, B. G., Datta, G., Chaddha, M., and Anantharamaiah, G. M. (2004) J. Biol. Chem. 279, 51404 -51414). In the present work, we demonstrate that the peptide 3F-2, which has more potent anti-inflammatory activity in vitro when administered intraperitoneally to female apoE null mice (20 g/mouse/day) for 6 weeks, inhibits atherosclerosis (lesion area 15,800 ؎ 1000 m 2 , n ‫؍‬ 29), whereas 3F 14 does not (lesion area 20,400 ؎ 1000 m 2 , n ‫؍‬ 26) compared with control saline administered (19,900 ؎ 1400 m 2 , n ‫؍‬ 22). Plasma distribution of the peptides differs in that 3F-2 preferentially associates with high density lipoprotein, whereas 3F 14 preferentially associates with apoB-containing particles. After intraperitoneal injection of 14 C-labeled peptides, 3F 14 reaches a higher maximal concentration and has a longer half-time of elimination than 3F-2. A study of the effect of these peptides on the motional and organizational properties of phospholipid bilayers, using several NMR methods, demonstrates that the two peptides insert to different extents into membranes. 3F-2 with aromatic residues at the center of the nonpolar face partitions closer to the phospholipid head group compared with 3F 14 . In contrast, only 3F 14 affects the terminal methyl group of the acyl chain, decreasing the 2 H order parameter and at the same time also decreasing the molecular motion of this methyl group. This dual effect of 3F 14 can be explained in terms of the cross-sectional shape of the amphipathic helix. These results support the proposal that the molecular basis for the difference in the biological activities of the two peptides lies with their different interactions with membranes.

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