Moreover, the qRT-PCR also showed the upregulation of the IL23B (p40) gene, which Smad inhibitor however was very donor specific with a variation of 3 orders of magnitude (Figure 3; Additional file 16, Table S13). Thus infection of the monocytes with all gram-positive bacteria led to markedly increased transcription of both genes necessary to form the active IL23 cytokine. At the same time microarray as well the qRT-PCR data showed only limited upregulation or even downregulation of the IL12A (p35) mRNA transcription for the individual donors, which confirms the dominant role of IL23 versus IL12. Both IL23 and

IL12 can activate the transcription activator STAT4 in Th-cells and NK cells, and stimulate the production of interferon γ (IFNγ) [15, 16]. However, as the monocyte population used in this study is almost free of other leukocytes including Th-cells and NK cells, the IFNγ back loop that triggers secondary cytokine expression in the monocytes is absent, hence providing an explanation as to why other major inflammatory cytokines like IL1 and TNF were not substantially upregulated. Yet real time RT-PCR tests with IFNγ specific primers revealed upregulation of IFNγ mRNA by all three pathogens (9.5 fold upregulated by LM, 6.2 by SA and 1.8 fold by SP) suggesting an ability for self-priming of learn more the monocytes even in the absence of additional effector cells. The proinflammatory reaction

with the hallmark upregulation of IL23 involved also the chemokines CCL8, CCL14 and osteopontin (3 to 9 fold upregulated and common for all pathogens). CCL14 weakly activates monocytes but induces the proliferation of CD34+ progenitor cells. CCL8 is chemotactic and is active on all leucocytes [17, 18]. Osteopontin (SPP1, OPN) induces the migration of macrophages and dendritic cells to the site of inflammation [19]. This elevated transcription of chemokine genes is aided by the upregulation of downstream members of the inflammation signaling e.g. PDE4B, which is the predominant phosphodiesterase in macrophages and counteracts the inflammation inhibition by cyclic nucleotide

signaling [20–22]. In circulating human monocytes PDE4B assists the TNFa synthesis and release in response to LPS [21, 22] thus our results show that upregulation of PDE4B can also be stimulated VAV2 by alternative PAMP sensors since the gram positive bacteria we have used do not produce LPS. Recently it was discovered that bacterial LPS and non methylated CpG oligonucleotides, which signal via TLR4 and TLR9 respectively, strongly induce the expression of SOCS1 and SOCS3, and attenuate the ability of macrophages to respond to subsequent stimulation by IFNγ or IL-6 [23]. Similarly it has been described that NALP2 (PAN1) protein expression was also upregulated by LPS and interferons (IFNβ and IFNγ) and transient overexpression of NALP2 led to inhibition of NFkB signaling [24].