Roles of p38 Mitogen-Activated Protein Kinase, NF-κB, and Protein Kinase C in Proinflammatory Cytokine mRNA Expression by Human Peripheral Blood Leukocytes, Monocytes, and Neutrophils in Response toAnaplasma phagocytophila

Abstract

Anaplasma phagocytophila, an obligately intracellular bacterium of granulocytes, causes human granulocytic ehrlichiosis. Within 2 h after addition of A. phagocytophila, interleukin-1␤ (IL-1␤), tumor necrosis factor alpha (TNF-␣), and IL-6 mRNAs are induced in human peripheral blood leukocytes (PBLs) or monocytes in vitro. However, neutrophils generate only IL-1␤ mRNA. In the present study, signaling pathways for induction of these three cytokines were examined. TNF-␣ and IL-6 mRNA expression by PBLs was inhibited with SB 203580 (a p38 mitogen-activated protein kinase [MAPK] inhibitor), MG-132 (a proteasome inhibitor), and SN-50 (an NF-B inhibitor). Activation of p38 MAPK and NF-B mRNAs in monocytes was detectable within 15 to 30 min after addition of A. phagocytophila. Expression of these two cytokine mRNAs in PBLs and monocytes was also dependent on protein kinase C (PKC), protein kinase A (PKA), and protein tyrosine kinase (PTK). IL-1␤ mRNA expression by neutrophils was not dependent on p38 MAPK, and p38 MAPK was not activated in neutrophils incubated with A. phagocytophila. IL-1␤ mRNA induction by PBLs, monocytes, and neutrophils was dependent on PKC and PKA. Neutrophil expression of IL-1␤ mRNA was dependent on transglutaminase, phospholipase C, and PTK, all of which are also required for internalization of A. phagocytophila. However, monocyte expression of IL-1␤ mRNA was less dependent on these enzymes. These results suggest that A. phagocytophila transduces different signals between its host neutrophils and monocytes for proinflammatory cytokine generation.

Anaplasma phagocytophilumDelay of Neutrophil Apoptosis through the p38 Mitogen-Activated Protein Kinase Signal Pathway

“…We demonstrated upregulation of CD11b, down-modulation of L-selectin (CD62L) (13), and prolonged degranulation in A. phagocytophilum-infected neutrophils (12), and these phenomena could be mediated in part by p38 MAPK as well. Kim and Rikihisa also examined p38 MAPK in human neutrophils infected by A. phagocytophilum and concluded that this pathway was not activated (27). The reasons for these discrepant results are unclear; however, the uniform production from A. phagocytophilum-infected neutrophils of chemokines known to stimulate p38 MAPK and the activation of this pathway in neutrophils by other bacterial components, such as LPS (4), argue against its absence.…”

“…MAPK activation was previously shown in monocytes, but not neutrophils, exposed to A. phagocytophilum (27). However, given the known regulatory function of p38 MAPK in apoptosis, this pathway requires a more in-depth examination of A. phagocytophilum-infected neutrophils.…”

Saccharomyces cerevisiaeandCandida albicansStimulate Cytokine Secretion from Human Neutrophil-Like HL-60 Cells Differentiated with Retinoic Acid or Dimethylsulfoxide

“…15,16) In response to bacteria such as Anaplasma spp., Ehrlichia spp., Salmonella typhimurium and Pseudomonas aeruginosa, neutrophils enhance the transcript levels and/or protein secretion of IL-1/, IL-6, IL-8, macrophage inflammatory protein-1 (MIP-1) and/or tumor necrosis factor-(TNF-). [17][18][19][20] Furthermore, numerous neutrophils accumulate in areas infected by fungi. 21) Freshly isolated neutrophils secrete IL-8 in response to heatkilled S. cerevisiae and C. albicans, and MIP-1 to heat-killed C. albicans, albeit to a lower extent, compared to bacterial responses.…”

Protein tyrosine kinase and mitogen-activated protein kinase signalling pathways contribute to differences in heterophil-mediated innate immune responsiveness between two lines of broilers

“…Likewise, there are reports in the mammalian literature describing signalling pathway differences depending on the agonist used (Yum et al, 2001;Strassheim et al, 2004). As we have seen with heterophils, regulation of interleukin-6 and other inflammatory cytokines in mammalian cells is also mediated by NF-kB (Kim & Rikihisa, 2002;Cloutier et al, 2007;Requena et al, 2009;Cao et al, 2010;Khalaf et al, 2010), and interleukin-8 production is regulated more so by AP-1 in T cells (Khalaf et al, 2010), and NF-kB in monocytes (Vitiello et al, 2004). Additionally, deficiencies in AP-1 proteins are associated with increased susceptibility to S. typhimurium (Maruyama et al, 2007).…”

“…Phosphorylation of p38 and JNK influences downstream cytokine/chemokine production (Kim & Rikihisa, 2002;Cloutier et al, 2003Cloutier et al, , 2007. Induction of pro-inflammatory cytokines and chemokines by neutrophils is dependent on the activation of p38 (Cloutier et al, 2007), while JNK has a lesser role in inflammatory cytokine/chemokine production (Cloutier et al, 2003).…”