LECT2 association with macrophage-mediated killing of Helicobacter pylori by activating NF-κB and nitric oxide production

Abstract

ABSTRACT. Helicobacter pylori employs unique methods to colonize the stomach, which induces chronic inflammation. It is also able to avoid eradication by macrophages and other immune cells. Leukocyte cell-derived chemotaxin 2 (LECT2), a multi-functional cytokine involved in many pathological conditions, has recently been shown to activate macrophages via the CD209a receptor. Therefore, we aimed to investigate the effects of LECT2 on H. pylori-infected macrophages. Macrophages were treated with recombinant LECT2, and both their ability to kill H. pylori and produce nitric oxide were analyzed. Western blot was performed to determine nuclear translocation and protein phosphorylation of p65, a subunit of nuclear factor (NF)-kB. Transfection experiments were performed to analyze the signaling pathway of LECT2 in macrophages. We found that treatment with LECT2 enhanced H. pylori killing and nitric oxide production in macrophages. In addition, DNA-binding activity and nuclear translocation of p65 were up-regulated by LECT2 treatment. Furthermore, we found that NFkB activation by LECT2 was mediated by Raf-1 in macrophages, and Raf-1 phosphorylation was specifically altered in response to LECT2. Moreover, LECT2 induced Ser28 phosphorylation in the intracellular domain of CD209a. CD209a Ser28 phosphorylation was required for LECT2-induced Raf-1 and NF-kB activation in RAW264.7 macrophages. Our study showed that the effects of LECT2 on H. pylori killing and nitric oxide production were dependent on CD209a phosphorylation, Raf-1, and NF-kB activation. Together, these results demonstrate for the first time that exposure to LECT2 can modulate specific intracellular mechanisms downstream of CD209a to enhance H. pylori killing and nitric oxide production in macrophages.

LECT2 promotes inflammation and insulin resistance in adipocytes via P38 pathways

“…Impaired insulin signaling leading to insulin resistance is a main characteristic of metabolic disorders and type 2 diabetes. LECT2 has been previously documented to show potent pro-inflammatory effects in macrophages (Lu et al 2013, Shen et al 2016, endothelial cells (Hwang et al 2015a) and hepatocytes (Anson et al 2012). Moreover, LECT2 has been shown to induce insulin resistance in the liver (Hwang et al 2015b) and in skeletal muscle (Lan et al 2014).…”

“…Journal of Molecular Endocrinology a pro-inflammatory response (Lu et al 2013, Hwang et al 2015a, Shen et al 2016. Suppression of CD209 by siRNA abrogated the effect of LECT2 on P38 phosphorylation (Fig.…”

“…In the present study, we suggest CD209/P38dependent pathway as a novel mechanism of the effects of LECT2 on inflammation and insulin resistance in differentiated adipocytes. In addition, LECT2 has been reported to induce activation of NF-κB in macrophages (Shen et al 2016) and pro-inflammatory cytokines through CD209 receptor-dependent JNK pathway in human endothelial cells (Hwang et al 2015a). LECT2 also impairs insulin signaling in hepatocytes (Hwang et al 2015b) and skeletal muscle through JNKmediated pathway (Lan et al 2014).…”

Loss of bound zinc facilitates amyloid fibril formation of leukocyte-cell-derived chemotaxin 2 (LECT2)

“…Leukocyte-cell-derived chemotaxin 2 (LECT2) is a 133-residue protein synthesized in the liver for secretion into the blood. LECT2 plays roles in immunity ( 1 , 2 , 3 ), inflammatory cytokine responses ( 4 , 5 ), liver angiogenesis ( 6 ), and other processes ( 7 , 8 , 9 , 10 ). In accordance with its multifunctional status, LECT2 is associated with numerous diseases.…”

Helicobacter: Inflammation, immunology and vaccines

“…Several groups investigated the mechanisms in activation of M1 macrophages to enhance H. pylori killing. Shen et al . found an important role for the inflammatory cytokine leukocyte cell‐derived chemotaxin 2 (LECT2), which stimulated bactericidal activity and nitric oxide production.…”