Whether p38 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase cascades are required for inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) accumulation in RAW 264.7 murine macrophages exposed to lipopolysaccharide (LPS) plus recombinant interferon-gamma (rIFN-gamma) was investigated. By use of Western blotting for iNOS detection and ELISA for quantitation of TNF secretion, three selective inhibitors of these pathways were tested (the p38 inhibitors SB202190 and SB203580 and the MEK 1,2/ERK inhibitor PD98059). Dose-related inhibition of iNOS production was demonstrated when inhibitors were added 1 h before, simultaneously with, or 1 h after LPS plus rIFN-gamma stimulation. In contrast, inhibition of TNF secretion was observed only when cells were preincubated with these agents. Thus, both the p38 and ERK pathways are involved in the up-regulation of iNOS and TNF production by murine macrophages, and specific inhibitors of these pathways block macrophage iNOS production even when added 1 h after activation of these cells.

Macrophage activation by CpG DNA requires toll-like receptor 9 and the adaptor protein MyD88. Gram-negative bacterial lipopolysaccharide also activates macrophages via a toll-like receptor pathway (TLR-4), but we and others have reported that lipopolysaccharide also stimulates tyrosine phosphorylation in macrophages. Herein we report that exposure of RAW 264.7 murine macrophages to CpG DNA (but not non-CpG DNA) provoked the rapid tyrosine phosphorylation of vav1. PP1, a selective inhibitor of src-related tyrosine kinases, blocked both the CpG DNA-mediated tyrosine phosphorylation of vav1 and the CpG DNA-mediated up-regulation of macrophage tumor necrosis factor secretion and inducible nitric-oxide synthase protein accumulation. Furthermore, we found that the inducible expression of any of three dominant interfering mutants of vav1 (a truncated protein, vavC; a form containing a point mutation in the regulatory tyrosine residue, vavYF174; and a form with an in-frame deletion of six amino acids required for the guanidine nucleotide exchange factor (GEF) activity of vav1 for rac family GTPases, vavGEFmt) consistently inhibited CpG DNA-mediated up-regulation of tumor necrosis factor secretion and inducible nitric-oxide synthase protein accumulation in RAW-TT10 macrophages. Finally, we determined that CpG DNA-mediated up-regulation of NF-B activity (but not mitogen-activated protein kinase activation) was inhibited by preincubation with PP1 or by expression of the truncated vavC mutant. Taken together, our results indicate that the tyrosine phosphorylation of vav1 by a src-related tyrosine kinase or kinases plays an important role in the macrophage response to CpG DNA.Certain bacterial DNA sequences are recognized by the vertebrate immune system as foreign and directly activate B lymphocytes and macrophages (1-3). Unmethylated CpG dinucleotides in particular sequence contexts (CpG motifs, e.g. CACGTT for murine cells, GTCGTT for human cells) occur frequently in bacterial DNA but not in vertebrate DNA (3). Synthetic oligodeoxynucleotides containing these sequences (CpG DNA) stimulate macrophages to produce important inflammatory mediators such as tumor necrosis factor (TNF) 1 and nitric oxide (NO) (2-4). Although exposure of animals to CpG DNA also leads to a robust T helper cell 1 cytokine response in most cases, the effects of CpG DNA on T cells are indirect, resulting from the production of innate cytokines such as type I interferons, interleukin-12, and interleukin-18 (3).We and others have implicated hck and other src-related tyrosine kinases (5-9) and substrates of these kinases, including vav1 (10, 11), in the macrophage response to Gram-negative bacterial LPS. Although targeted disruption of three src family kinases (hck, lyn, fgr), alone or in combination, has failed to demonstrate an essential role for this pathway in macrophage activation by LPS (12), this may be due to compensation by other src family members. Recent studies with highly src family-selective tyrosine kinase inhibitors (13) provide additiona...

ClinicalTrials.gov: NCT02387606; EudraCT number: 2014-005041-41.

Although respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in infants and young children, attempts to develop an effective therapy have so far proved unsuccessful. Here we report the preclinical profiles of PC786, a potent nonnucleoside RSV L protein polymerase inhibitor, designed for inhalation treatment of RSV infection. PC786 demonstrated a potent and selective antiviral activity against laboratory-adapted or clinical isolates of RSV-A (50% inhibitory concentration [IC50], <0.09 to 0.71 nM) and RSV-B (IC50, 1.3 to 50.6 nM), which were determined by inhibition of cytopathic effects in HEp-2 cells without causing detectable cytotoxicity. The underlying inhibition of virus replication was confirmed by PCR analysis. The effects of PC786 were largely unaffected by the multiplicity of infection (MOI) and were retained in the face of established RSV replication in a time-of-addition study. Persistent anti-RSV effects of PC786 were also demonstrated in human bronchial epithelial cells. In vivo intranasal once daily dosing with PC786 was able to reduce the virus load to undetectable levels in lung homogenates from RSV-infected mice and cotton rats. Treatment with escalating concentrations identified a dominant mutation in the L protein (Y1631H) in vitro. In addition, PC786 potently inhibited RSV RNA-dependent RNA polymerase (RdRp) activity in a cell-free enzyme assay and minigenome assay in HEp-2 cells (IC50, 2.1 and 0.5 nM, respectively). Thus, PC786 was shown to be a potent anti-RSV agent via inhibition of RdRp activity, making topical treatment with this compound a novel potential therapy for the treatment of human RSV infections.

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Role of complement receptor type three and serum opsonins in the neutrophil response to yeast. Complement 4, 75-86. 6. Czop, J. K., Austen, K. F. (l985a) A 13-glucan inhibitable receptor on human monocytes: Its identity with the phagocytic receptor for particulate activators of the alternative complement pathway.

Exposure of any of six clinical isolates of Staphylococcus aureus to daptomycin alone or in combination with vancomycin or oxacillin (compared with vancomycin or oxacillin alone) led to a dampened macrophage inflammatory response with diminished tumor necrosis factor secretion and reduced accumulation of inducible nitric oxide synthase protein.

The temporal requirements for tyrosine phosphorylation in the induction of tumor necrosis factor (TNF) and inducible nitric oxide synthase (NOS) were compared in the routine macrophage cell line RAW 264.7. Preincubation of RAW 264.7 cells with herbimycin A or genistein (but not with either of three tyrphostins tested) significantly blocked TNF and NOS production on exposure of these cells to combinations of lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). The addition of either genistein or herbimycin A to RAW 264.7 cell cultures 1-6 It after stimulation with LPS and IFN-gamma had little or no effect on TNF production but markedly inhibited NOS protein accumulation. Together these data indicate that tyrosine kinase inhibitors block NOS production at a point well downstream of the initial wave of LPS- and IFN-gamma-mediated protein tyrosine phosphorylation.