MEK inhibitors increase the mortality rate in mice with LPS-induced inflammation through IL-12-NO signaling

Abstract Lipopolysaccharide (LPS) is an endotoxin that can cause an acute inflammatory response. Nitric oxide (NO) is one of the most important innate immune system components and is synthesized by inducible NOS (iNOS) in macrophages in response to stimulation with LPS. LPS activates the RAS-RAF-mitogen-activated protein kinase/ERK kinase (MEK)-extracellular-signal-regulated kinase (ERK) signaling cascade in macrophages. The purpose of this study was to examine how the combination of LPS and MEK inhibitors, which have been used as anticancer agents in recent years, affects inflammation. We showed that MEK inhibitors enhanced iNOS expression and NO production in LPS-stimulated mouse bone marrow-derived macrophages. A MEK inhibitor increased the mortality rate in mice with LPS-induced inflammation. The expression of the cytokine interleukin-12 (IL-12) in macrophages was enhanced by the MEK inhibitor, as shown by a cytokine array and ELISA. IL-12 enhanced iNOS expression and NO production in response to LPS. We also showed that tumor necrosis factor (TNF-α) was secreted by macrophage after stimulation with LPS and that TNF-α and IL-12 synergistically induced iNOS expression and NO production. An anti-IL-12 neutralizing antibody prevented NO production and mortality in an LPS-induced inflammation mouse model in the presence of a MEK inhibitor. These results suggest that the MEK inhibitor increases the mortality rate in mice with LPS-induced inflammation through IL-12-NO signaling

A simple method to increase the proportion of bone marrow-derived macrophages positive for M-CSFR using the reducing agent dithiothreitol (DTT)

Only a few bone marrow-derived macrophages (BM-MΦ) are positive for macrophage colony-stimulating factor receptor (M-CSFR). Thus, a method is needed to increase the proportion of BM-MΦ that are positive for M-CSFR to facilitate the investigation of the effects of M-CSFR downregulation on various diseases. We used mouse primary BM-MΦ to evaluate the expression of M-CSFR on the cytoplasmic membrane using flow cytometry. Treatment with a reducing agent, dithiothreitol (DTT), increased the proportion of BM-MΦ that were positive for M-CSFR, and this increase was time dependent. We next determined whether DTT-treated BM-MΦ can lead to the downregulation of M-CSFR. Treatment with lipopolysaccharide (LPS) for 24 h. decreased the proportion of DTT-treated BM-MΦ that were positive for M-CSFR. These results suggest that DTT treatment increases the proportion of BM-MΦ that are positive for M-CSFR and that the upregulation of M-CSFR on BM-MΦ can be abrogated by treatment with LPS. Here, we propose a simple method to increase the number of M-CSFR-positive BM-MΦ using the reducing agent DTT, which could be useful in investigations of the relationship between the downregulation of M-CSFR and some diseases. • The proportion of BM-MΦ that expresses M-CSFR on the membrane increases by approximately twice following DTT treatment. Method name: Method to increase the proportion of macrophages positive for M-CSFR, Keywords: Bone marrow-derived macrophages, Macrophage colony-stimulating factor receptor (M-CSFR), Dithiothreitol (DTT), Lipopolysaccharide (LPS), Atherosclerosi

Cat and Dog Ownership in Early Life and Infant Development : A Prospective Birth Cohort Study of Japan Environment and Children's Study

Contact with companion animals has been suggested to have important roles in enhancing child development. However, studies focused on child development and pet ownership at a very early age are limited. The purpose of the current study was to investigate child development in relation to pet ownership at an early age in a nationwide prospective birth cohort study: the Japan Environment and Children's Study. Associations between cat and dog ownership at six months and infant development at 12 months of age were examined in this study. Infant development was assessed using the Ages & Stages Questionnaires(TM) (ASQ-3) at 12 months. Among participants of (Japan Environment and Children's Study) JECS, those with available data of cat and dog ownership at six months and data for the ASQ-3 at 12 months were included (n = 78,868). Having dogs showed higher percentages of pass in all five domains measured by ASQ-3 (communication, gross motor, fine motor, problem-solving, and personal-social) compared to those who did not have dogs. Significantly decreased odds ratios (ORs) of developmental delays were observed in association with having dogs in all fix domains (communication: OR = 0.73, gross motor: OR = 0.86, fine motor: OR = 0.84, problem-solving: OR = 0.90, personal-social: OR = 0.83). This study suggested that early life dog ownership may reduce the risks of child developmental delays