Interleukin (IL)-10 is known to protect mice against the lethal effects of lipopolysaccharides (LPS) and is considered to be an anti-inflammatory cytokine which suppresses the production of pro-inflammatory cytokines. We have examined the interactions of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) with IL-10. Neutralization of TNF-alpha in murine bone marrow-derived macrophages resulted in a significant reduction of LPS-inducible IL-10 production. In mice, injection of 5 mg/kg LPS induced circulating IL-10 with a biphasic time course exhibiting an early peak 1.5 h after challenge (synchronous with TNF-alpha) and, after a nadir at 6 h, a second increase between 8 and 12 h. Treatment of mice with neutralizing anti-mouse TNF-alpha antiserum significantly increased LPS-induced IL-10 plasma levels between 1.5 and 6 h but diminished those at 12 h, while circulating IL-6, interferon-gamma (IFN-gamma) and granulocyte colony-stimulating factor (G-CSF) concentrations were attenuated overall, without a biphasic response. Analysis of LPS-induced IL-10 mRNA expression in different tissues 1 h and 8 h after LPS or LPS plus anti-TNF-alpha revealed that the amount of transcripts in the liver correlated with circulating early and late IL-10 levels. Our findings suggest that endogenous TNF-alpha down-regulates the early and up-regulates the late LPS-induced IL-10 synthesis in vivo and that the liver is the major source of circulating IL-10 after stimulation with LPS.

Wound healing in healthy individuals proceeds at an optimal rate. However, in patients, with -- e.g.-- locally impaired blood flow or diabetes, chronic wounds develop and often become infected. Chronic wounds mean a low quality of life for the afflicted patients, not to mention enormous costs. Rather than using recombinant growth factors to accelerate wound healing, we employed the toll-like receptor agonist macrophage-activating lipopeptide-2 (MALP-2) to improve the healing of full-thickness excision skin wounds in an animal model with obese, diabetic mice. A gene array experiment suggested that MALP-2 stimulates the release of various mediators involved in wound healing. Further data to be presented in this study will show (i) that MALP-2 is capable of stimulating the appearance of the monocyte chemoattractant protein-1 at the wound site, (ii) that this leads to increased leucocyte and, in particular, macrophage infiltration and (iii) that MALP-2-treated wounds closed 2 weeks earlier than vehicle-treated controls. MALP-2, thus, appears to stimulate the early inflammatory process needed to set in motion the ensuing consecutive natural steps of wound healing resulting in wound closure.

1 In this study we describe that activin A, a transforming growth factor (TGF) b-like polypeptide a ects the expression of in¯ammatory response genes and their products. 2 In rat bone marrow derived macrophages 15 nM activin A caused the stimulation of prostaglandin (PG) E 2 and thromboxane (TX) A 2 formation, production of nitrite as a marker for nitric oxide (NO) and the release of the cytokines tumour necrosis factor (TNF) a and interleukin (IL) -1b. As shown by mRNA analysis induction of cyclo-oxygenase-2 and inducible nitric oxide synthase by activin A gave rise to the enhanced release of prostanoids and NO. 3 Costimulation of bone marrow derived macrophages with 15 nM activin A and 100 nM 12-Otetradecanoyl-phorbol 13-acetate (TPA) potentiated the synthesis of prostanoids in a synergistic manner. With respect to NO formation the e ect of activin A and TPA was additive. 4 In contrast to the nitrite production activin A induced PGE 2 synthesis was susceptible to tyrosine kinase inhibition by genistein and tyrphostin 46 (IC 50 was 10 and 20 mM, respectively). This observed inhibition was caused by the selective suppression of activin A induced cyclo-oxygenase-2 mRNA expression. Further, the release of TNFa in the presence of activin A was potentiated by tyrosine kinase inhibition. 5 In summary, we report that activin A exerts proin¯ammatory activity which results in the formation of prostanoids, NO and cytokines in rat bone marrow derived macrophages. Tyrosine kinase dependent and independent signalling pathways are involved leading to the increased synthesis of these metabolites. Based upon these results, we speculate that activin A may be considered as a possible component of in¯ammatory processes a ecting at least the haematopoietic system.

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Granulocyte colony-stimulating factor (G-CSF) recruits and primes neutrophilic granulocytes. The role of endogenous and exogenous G-CSF was examined in a murine fecal peritoneal infection model characterized by rapid production of high levels of circulating G-CSF. Pretreatment with anti-murine G-CSF for 5 days reduced neutrophil counts by 50% and sensitized mice to sublethal peritonitis. There were more aerobic bacteria in livers of antiserum-pretreated animals but fewer neutrophils in peritoneal cavities. Pretreatment with 100 micrograms/kg recombinant murine G-CSF intravenously for 2 days raised neutrophil counts 5-fold and significantly protected animals against lethal peritonitis. A similar prophylactic administration of murine granulocyte-macrophage (GM)-CSF neither augmented leukocyte numbers nor protected infected mice. These results show a dissociation between the pharmacologic properties of GM-CSF and G-CSF and demonstrate the crucial role of endogenous G-CSF in controlling neutrophil-dependent defense against bacterial invasion in infection.